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Aim: To investigate whether silibinin impacts diabetic periodontitis (DP) via mitochondrial regulation. Materials and Methods: In vivo, rats were divided into control, diabetes, DP and DP combined with silibinin groups. Diabetes and periodontitis were induced by streptozocin and silk ligation, respectively. Bone turnover was evaluated by microcomputed tomography, histology and immunohistochemistry. In vitro, human periodontal ligament cells (hPDLCs) were exposed to hydrogen peroxide (H2O2) with or without silibinin. Osteogenic function was analysed by Alizarin Red and alkaline phosphatase staining. Mitochondrial function and biogenesis were investigated by mitochondrial imaging assays and quantitative polymerase chain reaction. Activator and lentivirus-mediated knockdown of peroxisome proliferator-activated receptor gamma-coactivator 1-alpha (PGC-1α), a critical regulator of mitochondria biogenesis, was used to explore the mitochondrial mechanisms. Results: Silibinin attenuated periodontal destruction and mitochondrial dysfunction and enhanced mitochondrial biogenesis and PGC-1α expression in rats with DP. Meanwhile, silibinin promoted cell proliferation, osteogenesis and mitochondrial biogenesis and increased the PGC-1α level in hPDLCs exposed to H2O2. Silibinin also protected PGC-1α from proteolysis in hPDLCs. Furthermore, both silibinin and activator of PGC-1α ameliorated cellular injury and mitochondrial abnormalities in hPDLCs, while knockdown of PGC-1α abolished the beneficial effect of silibinin. Conclusions: Silibinin attenuated DP through the promotion of PGC-1α-dependent mitochondrial biogenesis.

Objective: To explore and characterize the effect of the discrepancy between crestal bone height (CB) and pulp chamber floor (PCF) in the fatigue performance of endodontically-treated teeth rehabilitated with an endocrown restoration. Materials and methods: A total of 75 human molars free of defects, caries history or cracks were selected, then endodontically treated and randomly allocated into 5 groups (N = 15) according to the difference between PCF and CB, as follows: PCF 2 mm above, PCF 1 mm above, PCF leveled, PCF 1 mm below and PCF 2 mm below. Endocrown restorations were made with composite resin (Tetric N-Ceram, shade B3, Ivoclar) in 1.5 mm thickness and luted with a resin cement (Multilink N, Ivoclar) onto the dental elements. Monotonic testing was performed to define the fatigue parameters, and a cyclic fatigue test was used until failure of the assembly. The collected data were submitted to statistical survival analysis (Kaplan-Meier followed by Mantel-Cox and Weibull), fractographic analysis and finite element analysis (FEA) were performed as complementary analyzes. Results: The PCF 2 mm below and PCF 1 mm below groups presented the best results regarding fatigue failure load (FFL) and number of cycles for failure (CFF) (p < 0.05), but presented no difference between each other (p > 0.05). The PCF leveled and PCF 1 mm above groups presented no statistical difference between them (p > 0.05), but performed better than the PCF 2 mm above group (p < 0.05). The rate of favorable failures of PCF 2 mm above, PCF 1 mm above, PCF leveled, PCF 1 mm below and PCF 2 mm below groups were 91.7%, 100%, 75%, 66.7% and 41.7%, respectively. FEA showed different stress magnitudes according to the pulp-chamber design. Conclusion: The insertion level of the dental element to be rehabilitated with an endocrown interferes in the mechanical fatigue performance of the set. The discrepancy between the CB height and the PCF has a direct effect, where the higher the PCF in relation to the CB, the greater the risk of mechanical failure of the restored dental element.

Contains fulltext : 291751.pdf (Publisher’s version ) (Open Access) OBJECTIVES: The objective is to evaluate the long-term clinical survival and performance of direct and indirect resin composite restorations replacing cusps in vital upper premolars. METHODS: Between 2001 and 2007, 176 upper premolars in 157 patients were restored with 92 direct and 84 indirect resin composite restorations as part of an RCT. Inclusion criteria were fracture of the buccal or palatal cusp of vital upper premolars along with a class II cavity or restoration in the same tooth. RESULTS: Forty patients having 23 direct and 22 indirect composite restorations respectively, were lost to follow-up (25.6%). The cumulative Kaplan-Meier survival rates were 63.6% (mean observation time: 15.3 years, SE 5.6%) with an AFR of 2.4% for direct restorations and 54.5% (mean observation time: 13.9 years, SE: 6.4%) with an AFR of 3.3% for indirect restorations. The Cox regression analysis revealed a statistically significant influence of the patient's age at placement on the survival of the restoration (HR 1.036, p = 0.024), the variables gender, type of upper premolar, type of restoration, and which cusp involved in the restoration had no statistically significant influence. Direct composite restorations failed predominantly due to tooth fracture, indirect restorations primarily by adhesive failure (p

Objectives: To evaluate the effect of the remaining tooth structure and different CAD/CAM materials on the fatigue performance and failure mode of endodontically treated premolars restored with endocrowns. Materials and methods: Ninety maxillary premolars were endodontically treated and assigned into 6 groups (n = 15) according to the number of remaining axial walls (four, three, and two) and restorative materials (ultra-translucent zirconia 5Y-PSZ [KATANA UTML] and lithium disilicate [IPS e.max-CAD]). The specimens were subjected to cyclic fatigue loading test (initial load 200 N; 20 Hz). An incremental step load of 100 N per 10,000 cycles was applied until failure. The fatigue failure load (FFL) and number of failure cycles (CFFs) data were statistically analyzed with two-way ANOVA and Kaplan–Meier test (α = 0.05). Failed specimens were examined under a stereomicroscope 25 × and failure modes were determined. Results: FFL and CFF were significantly influenced by restorative material (p < 0.05). 5Y-PSZ endocrowns showed significantly higher FFL when compared with lithium disilicate. The number of remaining walls did not affect the fatigue behavior or failure mode of the specimens. Of the lithium disilicate restorations, 51% had repairable failures, while 95% 5Y-PSZ restorations had non-repairable failures. Conclusions: Zirconia endocrowns showed better FFL than lithium disilicate endocrowns, regardless of the number of remaining axis walls. Lithium disilicate and 5Y-PSZ endocrowns showed FFL higher than the normal masticatory loads. Clinical relevance: Restoring endodontically treated premolars with endocrown could be a promising treatment, regardless of the remaining axial walls. However, precaution should be taken in material selection since it affects the fatigue resistance and failure mode.

Objective: Establishing biocompatible, biodegradable, osteoconductive, and osteoinductive bone materials remains a challenging subject in the research of bone healing and bone regeneration. Previously, we demonstrated the osteogenic and osteoconductive effects of biomimetic calcium phosphate (BioCaP) incorporating with Icariin and/or bone morphogenetic protein 2 (BMP-2) at orthotopic sites. Methods: By implanting the BioCaP granules incorporated Icariin and/or BMP-2 into the dorsal subcutaneous pockets of adult male Sprague-Dawley (S-D) rats (6-7 weeks old), we investigated the osteoinductive efficacy of the samples. Micro-computed tomography(micro-CT) observations and histological slices were used to verify the osteoinduction of this system on the 2nd and 5th week. Statistical significances was evaluated using Turkey's post hoc test of one-way analysis of variance. Results: The osteoinduction of the BioCaP incorporated with BMP-2 or both agents was confirmed as expected. BioCaP with Icariin alone could not generate bone formation at an ectopic sites. Nevertheless, co-administration of Icariin increased bone mineral density (BMD; p < 0.01) (628mg HA/cm3 vs 570mg HA/cm3) and completely changed the distribution of newly formed bone when compared with the granules with BMP-2 alone, even though there was no significant difference in the volume of newly formed bone. In contrast, the BioCaP with both agents (37.86%) had significantly fewer remaining materials than the other groups by the end of the fifth week (53.22%, 53.62% and 48.22%) (p < 0.01). Conclusion: The co-administration of Icariin and BMP-2 increased BMD changed the distribution of newly formed bone, and reduced the amount of remaining materials. Therefore, Icariin can stimulate BMP-2 when incorporated into BioCaP granules at ectopic sites, which makes it useful for bone tissue engineering.

Objective: Recently, stainless steel (SSL) miniscrew implants have been used in orthodontic clinics as temporary anchorage devices. Although they have excellent physical properties, their biocompatibility is relatively poor. Previously, our group developed a two-phase biomimetic calcium phosphate (BioCaP) coating that can significantly improve the biocompatibility of medical devices. This study aimed to improve the biocompatibility of SSL by coating SSL surface with the BioCaP coating. Methods: Titanium (Ti) discs and SSL discs (diameter: 5 mm, thickness: 1 mm) were used in this study. To form an amorphous layer, the Ti discs were immersed in a biomimetic modified Tyrode solution (BMT) for 24 h. The SSL discs were immersed in the same solution for 0 h, 12 h, 24 h, 36 h and 48 h. To form a crystalline layer, the discs were then immersed in a supersaturated calcium phosphate solution (CPS) for 48 h. The surface properties of the BioCaP coatings were analysed. In addition, bovine serum albumin (BSA) was incorporated into the crystalline layer during biomimetic mineralisation as a model protein. Results: The morphology, chemical composition and drug loading capacity of the BioCaP coating on smooth SSL were confirmed. This coating improved roughness and wettability of SSL surface. In vitro, with the extension of BMT coating period, the cell seeding efficiency, cell spreading area and cell proliferation on the BioCaP coating were increased. Significance: These in vitro results show that the BioCaP coating can improve surface properties of smooth medical grade SSL and serve as a carrier system for bioactive agents.

BACKGROUND: Nickel-induced proliferation or cytokine release by peripheral blood mononuclear cells may be used for in vitro diagnosis of nickel allergy.OBJECTIVES: Aim of this study was to explore the nickel-specific cytokine profile to further elucidate the pathogenesis of nickel allergic contact dermatitis (ACD) and to identify potential new biomarkers for nickel ACD.METHODS: Peripheral blood mononuclear cells from patients and controls were cultured with T-cell skewing cytokine cocktails and/or nickel. Cytokine and chemokine concentrations were assessed in culture supernatants using validated multiplex assays. Specific cytokine production was related to history of nickel allergy and patch-test results.RESULTS: Twenty-one of the 33 analytes included in the analysis were associated with nickel allergy and included type1 (TNF-α, IFN-γ, TNF-β), type 2 (IL-3, IL-4, IL-5, IL-13), type 1/2 (IL-2, IL-10), type 9 (IL-9), type 17/1 (IL-17A[F], GM-CSF, IL-21) and type 22 (IL-22) derived cytokines as well as the T-cell/antigen presentation cell derived factors Thymus and activation regulated chemokine (TARC), IL-27 and IP-10. Receiver operator characteristics (ROC) analysis showed that IL-5 was the strongest biomarker for nickel allergy.CONCLUSIONS: A broad spectrum of 33 cytokines and chemokines is involved in the allergen-specific immune response in nickel allergic patients. IL-5 remains, next to the lymphocyte proliferation test, the strongest biomarker for nickel allergy.

Objective To study the fracture resistance and stress distribution pattern of translucent zirconia and fiber-reinforced composite cantilever resin-bonded fixed dental prostheses (RPFDPs) with two retainer designs. Materials and methods Forty human mandibular molars were divided into two groups according to the retainer design. The restorations included a premolar pontic and 2 retainer designs: (D1) inlay ring retainer and (D2) lingual coverage retainer. Each main group was then divided according to the material used (n = 10): zirconia (Z) or fiber-reinforced composite (FRC) (F). Restorations were cemented using dual polymerizing adhesive luting resin. All specimens were thermo-cycled (5–55 °C for 10,000 cycles), then subjected to dynamic loading (50 N, 240,000, and 1.6 Hz) and fracture resistance test. The finite element analysis includes the two models of retainer designs used in the in vitro test. Modified von Mises stress values on enamel, dentin, luting resin, and restorations were examined when the restorations failed. Results A significantly higher failure load was recorded for zirconia groups (505.00 ± 61.50 and 548.00 ± 75.63 N for D1Z and D2Z, respectively) than for FRC groups (345.00 ± 42.33 and 375.10 ± 53.62 N for D1F and D2F, respectively) (P = 0.001). With regard to failure mode, D2 showed a more favorable failure pattern than D1. Model D2 resulted in lower stresses in tooth structure than model D1, and zirconia transmitted more stresses to the tooth structure than FRC. Conclusions The lingual coverage retainer (D2) enhanced the biomechanical performance of the restoration/tooth complex. Considering the failure mode and tooth stress, FRC is a promising treatment option when constructing a cantilever RPFDP. Clinical relevance Dentists should be aware of the biomechanical behavior during the selection of the material and for the replacement of a single missing mandibular premolar tooth with minimally invasive RBFDP.

© 2022 by the authors.Intraoral three-dimensional scanning techniques could be used to improve dental practice, leading to an improved overall quality of the prosthetic devices and improved comfort for the patient. An accurate and precise intraoral scanner allows proper diagnosis, follow-up evaluation, and prosthesis application. The aim of this research is to evaluate the precision of an intraoral scanners (Medit i500, Medit Corp., Seoul, Korea), using open-source software in the digital workflow. The precision was compared through repetitions of the scanning process of the upper dental arch, following superimpositions in the whole 3D arch area. It was possible to display colorimetric maps for qualitative comparison, and the deviations of the values were classified as clinically acceptable. Within the limitation of this study, the clinically acceptable in vivo frequency of points’ deviation, or the precision, was obtained in 98.8% ± 1.4%; therefore, the use of open-source software can be a viable option in the digital workflow, improving patient follow ups with the 3D model superimposition.

The objective of this study was to evaluate the bond strength of different stabilized zirconias with resin cement and evaluate the susceptibility to thermal aging of the adhesive interface. Zirconia discs (Vita Zahnfabrik, Bad Säckingen, Germany) were obtained: 3Y-TZP first generation (translucent), 3Y-TZP third generation (high-translucent), 4Y-PSZ (super-translucent), and 5Y-PSZ (extra-translucent). Each disc had its surface polished with a standardized protocol. The specimens were cleaned and sintered according to the manufacturer’s recommendation (conventionally: ~12 h). However, 3Y-TZP groups were subdivided into subgroups and sintered following the speed sintering process (~80 min). After their sintering shrinkage, the dimensions of the final discs were 12 mm × 2 mm. The specimens were blasted with 50 μm aluminum oxide (1 cm distance, 2 bar pressure, and 2 s/cm²), cleaned, and silanized with an MDP primer. After the surface treatment, a resin cement cylinder was built on the ceramic surface (Ø = 1 mm; h = 2 mm). Half of the specimens of each group were subjected to a microshear bond strength test in a universal testing machine after 24 h of cementation, while the other half were subjected to thermocycling prior to the bond strength test (6000 cycles; 5 °C–55 °C, 30 s for each bath). Bond strength data were submitted to two-way ANOVA and Tukey’s test (95%), as well as Weibull analysis, to determine adhesive reliability. Bond strength was statistically different among the materials, and only 3Y-TZP third generation and 4Y-PSZ were not affected by thermal aging. The speed sintering method was statistically similar to the conventional process for 3Y-TZP first generation. However, 3Y-TZP third generation showed higher immediate bond strength when speed sintered. The Weibull modulus was superior for conventional 3Y-TZP third generation and 4Y-PSZ. In this study, thermal aging caused a degradation of the adhesive interfaces of 3Y-TZP first generation and 5Y-PSZ with the resin cement; however, it did not affect the interfaces of 3Y-TZP third generation and 4Y-PSZ. The speed sintering method did not affect the long-term bond strength with the resin cement. Adhesive reliability was superior for 3Y-TZP third generation and 4Y-PSZ.

Anchorage management is a key factor for successful orthodontic treatments, as it is essential to maximize desired tooth movements and mitigate unwanted forces. Skeletal anchorage, mainly miniscrew implants (MSIs) fixed to the bone, is widely used in daily orthodontic practice to achieve effective orthodontic tooth movement. Nevertheless, the clinical use of MSIs is associated with relatively low success rate, due to lack of osseointegration between implant surface and surrounding bone tissue. Therefore, this thesis aims to improve the osseointegration of MSIs by surface modification. In chapter 2, we comprehensively reviewed clinically applied surface modifications of MSIs, that is sandblasting, large-grit, acid etching (SLA), anodic oxidation (OA) and ultraviolet photofunctionalization (UVP). These techniques have positively influence in vitro and in vivo. However, the biological improvement in clinical studies is not so significant. Considering the limitation of current studies, finding an alternative to modify MSIs for bone tissue regeneration is proposed. In chapter 3, the biomimetic calcium phosphate (BioCaP) coating was successfully applied on medical grade smooth stainless steel (SSL) surface, with the immersing period in a biomimetic modified Tyrode (BMT) solution for 48 hours, followed by the same period in a supersaturated calcium phosphate solution (CPS). This optimum coating condition was selected because of the improved roughness and wettability of SSL surface after coating. Moreover, the cell seeding efficiency, cell spreading area and cell proliferation of human osteoblast-like cell MG63 were increased on the BioCaP coated SSL surface in vitro. To further explore the drug-carrier capability, and increase the osteogenic capability of the BioCaP coating, in chapter 4, BMP2 was incorporated into the BioCaP coating on smooth SSL surface, and compared with uncoated porous Ti, smooth SSL, and smooth SSL with the BioCaP coating. It showed that the BMP2 incorporated BioCaP coating was hydrophilic, with curly crystal-like morphology. In vitro studies showed that the cell seeding efficiency, cell proliferation, and osteogenic differentiation on this surface were significantly higher than that of SSL surface. In chapter 5, we aimed to evaluate the osteoconductivity of the BioCaP coating in vivo. The time-course osteointegration process of Ti mini-pin implants furnished with the BioCaP coating in a model of metaphyseal tibial was investigated, and bovine serum albumin (BSA) was involved as a model protein. A significant increase in BIC% occurred as early as at week 1 in the crystalline BioCaP coating group, compared with that at week 2 in no coating group and amorphous seeding layer group. These findings demonstrate that the BioCaP coating enhances the osteoconductivity of Ti mini-pin implants in vivo. Therefore, such surface modification has the potential in increasing the success rate of MSIs in orthodontic clinics. In chapter 6, anticancer drug-incorporated BioCaP coating on calcium phosphate particles have been proposed. Modified curcumin (mcur) was selected in this study because it can promote osteogenesis and selectively kill osteosarcoma cells.This mcur@BioCaP suppressed osteosarcoma cell and fibroblasts, and promoted osteogenesis. This mcur@BioCaP with osteogenic differentiation capability and enhanced anti-osteosarcoma effects can be a promising strategy for osteosarcoma post-surgical treatment. Based on the research described in this thesis, it can be concluded that the currently available surface modifications on miniscrew implants do not provide significant clinical improvement. Our research findings demonstrate that the BioCaP coating can be successfully applied on metallic surfaces and improves their biocompatibility and osteoconductivity. Moreover, the incorporation of BMP2 into this coating can be a promising proposal to facilitate early osseointegration. Taken together, the BioCaP coating can be a promising technique to increase the success rate of miniscrew implants in orthodontic applications.

Purpose: To determine the interfacial fracture energy (IFE) and stress distribution of Brazil-nut–shaped specimens made of translucent zirconia and resin cement Materials and Methods: Three types of translucent zirconia were used: 3Y-TZP (high, Vita YZ HT), 4Y-TZP (super, Vita YZ ST), and 5Y-TZP (extra, Vita YZ XT). The adhesive surfaces were air abraded and 10-MDP-based resin ce ment was used. The cemented Brazil-nut–shaped specimens, with an elliptical defect in the center (as in real Brazil nuts), were thermally aged (5°C–55°C; 40,000 cycles). The IFE test was conducted with a piston to apply compres sion on the specimen, while the adhesive interface was positioned at four different angles (0, 10, 20, and 30 de grees) to measure the IFE during tensile, shear, and mixed failure modes. All adhesive interfaces were observed to determine failure patterns. The finite element analysis (FEA) was used to calculate tensile and shear stress distri butions according to inclinations. Statistical analysis was conducted using the Kruskal-Wallis and Dunn’s post-hoc tests (95%), as well as the Mann-Whitney test (95%) was applied to compare each group regarding the aging factor. Results According to Kruskal-Wallis and Dunn’s post-hoc tests, there were no statistically significant differences be tween non-aged (p>0.05) and aged materials (p>0.05). However, there was a significant difference between aged and non-aged materials for all inclinations (p

The fluorescent carbon dots (CDs) have found their extensive applications in sensing, bioimaging, and photoelectronic devices. In general terms, the synthesis of CDs is straight-forward, though their subsequent purification can be laborious. Therefore, there is a need for easier ways to generate solid CDs with a high conversion yield. Herein, we used collagen waste as a carbon source in producing solid CDs through a calcination procedure without additional chemical decomposition treatment of the raw material. Considering a mass of acid has destroyed the original protein macromolecules into the assembled structure with amino acids and peptide chains in the commercial extraction procedure of collagen product. The residual tissues were assembled with weak intermolecular interactions, which would easily undergo dehydration, polymerization, and carbonization during the heat treatment to produce solid CDs directly. The calcination parameters were surveyed to give the highest conversion yield at 78%, which occurred at 300°C for 2 h. N and S atomic doping CDs (N-CDs and S-CDs) were synthesized at a similar process except for immersion of the collagen waste in sulfuric acid or nitric acid in advance. Further experiments suggested the prepared CDs can serve as an excellent sensor platform for Fe3+ in an acid medium with high anti-interference. The cytotoxicity assays confirmed the biosafety and biocompatibility of the CDs, suggesting potential applications in bioimaging. This work provides a new avenue for preparing solid CDs with high conversion yield.

Oral mucosa is exposed for many years to dental medical devices which contain metals. Overexposure to metal ions leaching from these dental devices may cause inflammation of mucosa/gingiva and even result in implant failure. Therefore, there is an urgent need to develop human physiologically relevant models which mimic the complex interactions between the oral soft tissues, the microbiome and metal ions leaching from dental medical devices. In this thesis, various human organotypic gingiva and skin models of different levels of complexity were developed to address the above concerns around dental medical devices. These include sterile ex vivo skin, reconstructed human skin (RHS) and reconstructed human gingiva (RHG) where culture methods were adapted to investigate the tissue response to metals and microbes. In Chapter 2, a full thickness ex vivo human skin to determine whether irritation and cytotoxicity occurred after topical application of nickel, palladium and titanium salts at patch-test relevant concentrations. After 24 hours of exposure, localized cytotoxicity was detected in the epidermis and dermis with separation at the basement membrane zone, formation of vacuoles, apoptotic nuclei, decreased metabolic activity and pro-inflammatory cytokine release. This chapter shows that current metal salt concentrations used in the skin patch test, by causing irritation and cytotoxicity, may confound the readout of an allergic reaction and therefore it should be considered to lower the salt concentration in the patch test. In Chapter 3, it was investigated whether the observed cytotoxicity to metals was enhanced by the presence of the Streptococcus mitis. After metal exposure, localized apoptosis was observed in the form of condensed apoptotic nuclei and vacuole formation within the epithelium and condensed nuclei in fibroblasts within the hydrogel of both RHG and RHS. S. mitis enhanced metal-mediated apoptosis in gingiva but not in skin. Apoptosis was mediated via the extrinsic pathway via caspase 8. Activation of the execution phase of apoptosis occurred via caspases 3 and 7, and PARP-1. These results show that metal-mediated cytotoxicity can indeed be exaggerated by commensal microbes. In Chapter 4, new strategies were introduced to the current RHG model: a) bacteria were applied within a low-concentration agar and b) penicillin and streptococcus (PS) was omitted from medium. This advanced microbe-RHG model was topically exposed to Streptococcus gordonii (commensal) or Aggregatibacter actinomycetemcomitans (pathogen) and co-cultured for 72 hours. S. gordonii did not influence RHG cytokine secretion. However, all cytokine secretion (IL-6, IL-8, CCL5, CCL20 CXCL1) secretion increased when RHG were co-cultured with A. actinomycetemcomitans. Both bacteria resulted in increased expression of RHG antimicrobial peptides (AMPs), with S. gordonii exposure resulting in the most Elafin secretion. In Chapter 5, a model which represented the barrier properties of the biological seal between the tooth and gingiva was next developed. This model is complementary to the existing implant-RHG model already present in our laboratory. An extracted premolar was incorporated into RHG. The gingival epithelium transitioned into a sulcus and junctional epithelium which was attached tightly to both the tooth and the lamina propria hydrogel. The sulcus depth (1.24 ± 0.233mm) and junctional epithelium length (2.45 ± 0.315mm) were comparable to that of healthy individuals. It will provide an excellent means to investigate gingivitis and peri-implantitis in the future. Taken together, our advanced organotypic skin and gingiva models enabled complex host-microbe interactions to be investigated identifying different commensal and pathogen effects on the host. This thesis shows that metal ions, which are present in many dental medical devices, do cause irritation and cytotoxicity (apoptosis) to the soft tissues (gingiva and skin) which come into contact with them. Notably, these detrimental effects are enhanced by commensal microbes present on both skin and gingiva.

Background/Aims: Professional and amateur athletes might have veneer restorations. The aim of this study was to investigate the protective effect of mouthguards on veneered anterior restorations. Methods: A nonlinear dynamic analysis was performed to simulate conditions during an impact with or without a custom-made mouthguard. Using a computer-aided design (CAD) software, a slice of a human maxilla was designed containing an upper right central incisor. The model was composed of mucosa, cortical bone, trabecular bone, periodontal ligament, dentin, enamel, and pulp tissue. The enamel was prepared (feather design), restored with an indirect veneer (1.0 mm thickness), and duplicated to simulate both conditions with or without a mouthguard (4 mm thickness). Both models were subdivided into finite elements using the computer-aided engineering (CAE) software. Frictionless contacts were used, and an impact was simulated in which a rigid sphere hit the model at 1 m s−1. Fixation was defined at the base of the bone. The elastic modulus of the veneer was assessed by using five different restorative materials (resin composite, hybrid ceramic, zirconia-reinforced lithium silicate, lithium disilicate, and zirconia). Von Mises stress, minimal principal stress, and maximum principal stress (in MPa) were obtained and plotted for visual comparison. Results: Von-Mises results showed higher stress concentrations in the veneer's cervical labial region for models without a mouthguard. Observing the quantitative results for each model, the highest compressive (709 MPa) and tensile (58 MPa) stresses occurred in the situation without a mouthguard with a zirconia veneer, while the lowest occurred in resin composite veneer with a mouthguard (8 and 5 MPa). The mouthguard was able to reduce the stresses in the tooth structure and it also reduced the risk of fracture in all conditions. Conclusions: Mouthguards were beneficial in reducing the effects of dental trauma regardless of the restorative material used to manufacture the indirect veneer, since they act by dampening the generated stresses during the trauma event. Equal impact stresses on a mouthguard will lead to higher stresses in veneered teeth with more rigid restorative materials leading to a less protective effect.

Item does not contain fulltext Implant-supported dental prosthetics are widely used in dental practice. Sufficient peri-implant bone tissue is a crucial prerequisite for the long-term success of this treatment, as insufficient peri-implant bone volume hampers dental implant installation and negatively influences dental implant stability. However, due to tooth extraction, bone metabolism diseases, and trauma, bone defects in the jaw are common in patients, particularly in the elderly and those suffering from underlying conditions. If this is the case, the alveolar ridge has to be augmented for reliable implant placement. Various biomaterials, growth factors (GFs) or GF-based products, and trace elements have been tested and used for alveolar ridge augmentation. Among those biomaterials, calcium phosphates (CaPs) are the most popular due to their promising biocompatibility, great osteoconductivity, and distinguishing osteogenesis. Combining CaPs with GFs or trace elements can further favor bone defect repair. This review mainly focuses on applying artificial CaP biomaterials and their combination with bioactive agents to repair bone defects in implant dentistry.

Error in Figure In the original publication [1], there was a mistake in Figure 2 as published. “Aging” labels referring to “Yes” and “No” on the figure were switched. The corrected Figure 2 appears below. The authors state that the scientific conclusions are unaffected. This correction was approved by the Academic Editor. The original publication has also been updated.

Mouthguards (MG) are protective devices that can reduce the risks of facial trauma. However, many athletes do not use them. Additionally, MG wear with coincidental parafunctional activity has not been considered. The aim of this study was to evaluate the stress distribution as a consequence of a direct impact comparing a conventional MG with a novel hybrid appliance (HMG). Using computer-aided design (CAD) software, a human skull was modeled with the teeth inserted into their respective alveolus. The models were divided according to the MG type (conventional or hybrid). The geometries were exported to the computer-aided engineering (CAE) software and the materials were considered isotropic. Fixation was defined at the base of the maxilla. The load was applied using a hockey puck. The total deformation (mm) and the von Mises stress (MPa) results were obtained for the MGs (conventional and hybrid), upper teeth, lower teeth, and maxillary bone. Despite the presence of an MG, it is still possible to observe generated stress in all structures. However, the hybrid design was more efficient than the conventional design in reducing the displacement during the impact and consequently the stress on the upper teeth, lower teeth, and maxillary bone. Higher stress magnitude was more concentrated at the inner portion of the hybrid design than the conventional device. The HMG appliance decreased the stress concentration in the teeth and in the bone, limiting the areas susceptible to injuries to the regions directly impacted by the hockey puck. Although the novel HMG may mitigate injury, some stress will still result, and any possible injury should be evaluated by a dental professional.

Periosteum is crucial to the initial healing of bone defects because it provides a stable periosteum-specific microenvironment and abundant osteogenic cells towards bone repair. However, the usage of autologous periosteum is restricted for limited availability. Xenogeneic decellularized periosteum (DP) preserves periosteum-specific cues but the hardly-controlled physicochemical properties render it inconvenient to use widely. Our study aimed to fabricate a tissue-engineered periosteum (TEP) with a continuous periosteum-specifically bioactive surface and tailored physicochemical properties by co-axial electrospinning of poly(ε-caprolactone) (PCL)/periosteal decellularized extracellular matrix (dECM) to promote bone defects healing. Before use, DP was confirmed for effective removal of residual DNA and well preservation of biological components, e.g., collagen and glycosaminoglycans. After optimization of fabrication processes, PCL/dECM co-axially electrospun membrane (PEC) bore an exquisite core-shell structure, which was effectively equipped with composite advantages of dECM and PCL. Notably, PEC stood out in terms of tensile strength and long-term durability within a physiological environment compared to that of the dECM uniaxial electrospun membrane (ECM). Besides, PEC exhibited remarkably better cell proliferation, migration, bio-mineralization, and osteogenic properties as compared to that of the electrospun PCL membrane. Moreover, PEC-TEP could significantly enhance the recovery of critical-sized bone defects in rats than that of PCL-TEP. To the best of our knowledge, biomimetic PEC-TEP was fabricated and used for the first time to repair bone defects. This novel strategy is promising to fabricate a dECM-based advanced membrane for tissue engineering.

Digital light processing (DLP) demonstrates significant application potential in the fine printing of dental zirconia. However, its complicated print process and post-treatments, such as sintering, are time consuming and sensitive to technical details. Therefore, the feasibility of using a high-speed sintering (HS) method for the fabrication of DLP-based zirconia was investigated in this study. Zirconia samples fabricated using DLP and conventional subtractive manufacturing techniques were all sintered following the different protocols: HS and conventional sintering (CS). Then, the density, Vickers hardness, fracture toughness, surface micro-topography, phase assemblage, and ageing resistance were assessed. The results showed that samples fabricated using the HS technique presented moderate Vickers hardness, fracture toughness, and ageing sensitivity in comparison with the other groups of specimens; moreover, they exhibited moderate initial cubic phase content and average grain size. Conversely, specimens sintered using the CS protocol with a peak temperature of 1580 °C showed high ageing sensitivity and unbalanced mechanical properties. The DLP- and SM-fabricated specimens showed similar trends for the studied properties. Overall, sintering parameters can significantly affect the macro- and micro-properties of DLP specimens, and the proposed HS method showed potential for producing DLP-based zirconia that is acceptable for clinical applications.

Objective: Bulk-fill resin composites are a special group of restorative materials designed to reduce chair time needed to insert a direct composite restoration. However, other factors determine the clinical success of a restorative material. Clinically the major reasons for failure of direct restorations are secondary caries and fracture of the restoration or the tooth itself. In the long-term composite resin restorations in posterior teeth may be prone to wear. As bulk-fill materials have their own composition that will determine their mechanical properties, the wear resistance may be affected as well. The aim of this in vitro study was to evaluate the wear of bulk-fill composites in comparison with a conventional hybrid composite. The null hypothesis was that there are no differences between the four bulk-fill materials and one traditional highly filled nanohybrid composite for posterior use when subjected to a two-body wear rate test and hardness measurement. Methods: Four bulk-fill composites SDR Smart Dentin Replacement (SDR), X-tra base (XBA), FiltekBulk Fill (FUP), Dual-Curing Bulk Composite (FBFL) and conventional nanohybrid resin composite Grandio (GDO) subjected to a two-body wear test against a stainless steel (SS) antagonist wheel. Scanning Electron Microscopy analysis was performed to detect the surface alterations. Microhardness of all samples was tested (n = 5) with a Vickers diamond indenter (5 indentations in each specimen). One-way ANOVA and Tukey's post hoc test (P < 0.01) were used to analyze differences in wear values. The hardness data were submitted to one-way ANOVA test, followed by the Tukey post hoc test (α = 0.05). T-test was applied to compare wear rate in time interval between one day and one month. Results: The highest wear rate values were recorded for SDR and the lowest wear rate values were for GDO. Hardness was the highest for GDO and the lowest for FBFL. Significance: The bulk-fill composites have a higher wear rate and lower hardness than the conventional nanohybrid composite, making them less suitable for stress-bearing restorations.

Made available in DSpace on 2022-05-01T09:31:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-03-01 Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) Objectives: This study evaluated the effect of deep margin elevation (DME) and restorative materials (leucite-reinforced glass–ceramics [C] vs. indirect resin composite [R]) on the fatigue behavior and stress distribution of maxillary molars with 2-mm deep proximal margins restored with MOD inlay. Methods: Fifty-two extracted human third molars were randomly assigned into four groups (n = 13): C; DME + C; R; and DME + R. Inlays were fabricated in CAD-CAM and bonded to all teeth. The fatigue behavior was assessed with the stepwise stress test (10,000 cycles/step; step = 50 N; 20 Hz; initial load = 200 N). Fatigue failure loads and the number of cycles were analyzed with 2-way ANOVA and Tukey’s test (p < 0.05) and Kaplan–Meier survival plots. The stress distribution was assessed with finite element analysis. The models were considered isotropic, linear, and homogeneous, and presented bonded contacts. A tripod axial load (400 N) was applied to the occlusal surface. The stress distribution was analyzed with the maximum principal stress criterion. Results: For fatigue, there was no difference for DME factor (p > 0.05). For the material factor, the load and number of cycles for failure were statistically higher in the R groups (p < 0.05). The finite element analysis showed that resin composite inlays concentrated more stress in the tooth structure, while ceramic inlays concentrated more stress in the restoration. Non-reparable failures were more frequent in the resin composite inlays groups. Conclusions: DME was not negative for fatigue and biomechanical behaviors. Resin composite inlays were more resistant to the fatigue test, although the failure mode was more aggressive. Clinical significance: DME does not impair mechanical behavior. Resin composite inlays failed at higher loads but with a more aggressive failure mode. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP Post-Graduate Program in Dentistry University of Taubaté (UNITAU), 09th Rua Dos Operários St., SP Graduate Program of Oral Science Prosthodontics Unit School of Dentistry Federal University of Santa Maria (UFSM) Roraima Av, RS School of Dentistry São Francisco University (USF), 218th São Francisco de Assis Av., SP Department of Restorative Dentistry Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP Department of Restorative Dentistry Institute of Science and Technology São Paulo State University (Unesp), 777th Eng. Francisco José Longo Av., SP

Made available in DSpace on 2022-05-01T09:30:47Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 This study aimed to evaluate the biomechanical behavior, stress distributions and bone microstrain of fixed partial dentures (FPD) with ceramic abutments supported on monotype zirconia implants, titanium implants and two-piece zirconia implants, using finite element analysis. A three-dimensional model of the jaw was simulated containing 1.0 mm thick cortical bone and cancellous bone tissue. A FPD and implant models (4.1 x 10 mm) were modeled containing a cement-retained implant abutment. These models were replicated in three groups with similar geometries: Titanium Implant and Zirconia Abutment (Ti-Zr); Zirconia Implant and Zirconia Abutment (Zr-Zr) and Monotype Zirconia Implant (Zr-S). An axial load of 300 N was applied to the center of the first premolar. The microstrain (με) and the Von-Mises stress (MPa) were assumed as failures criteria. For the three groups, a higher stress concentration was observed in the region of FPD connectors. The Ti-Zr group showed a higher stress concentration in the prosthesis and implant when compared to the other groups. However, the smaller elastic modulus of the titanium implant, in relation to the zirconia, provided a lower stress in the abutment and in the prosthetic screw. The monotype implant system allowed a more homogeneous stress distribution and its strain were predominantly located in the cervical region of the peri-implant bone tissue. Monotype or two-piece zirconia implants can be used for rehabilitation with FPD. However, the absence of separation between implant and abutment in the monotype system avoids the stress concentration in the prosthetic screw and reduced the peri-implant bone strain. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP) Department of Dentistry Universidade São Francisco (USF) Department of Implantology College of Denstristry CECAPE Juazeiro do Norte Department of Dentistry University of Taubaté (UNITAU) Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNESP)

Made available in DSpace on 2022-04-29T08:40:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Objective: The aim of this study was to investigate the effect of the hybrid abutment with different angles (0 and 15 degrees) on the stress distribution and deformation on maxillary implant-supported fixed prosthesis, using digital image correlation (DIC) and finite element analysis (FEA). Materials and Methods: For DIC, two situations were considered: conventional straight implant placement and implant placement with 15 degrees inclination. Different zirconia mesostructures were milled, one straight and the other with a 15-degree angulation to correct the implant positioning. Then, the zirconia mesostructures were cemented to the titanium base (Ti base), and both groups received a lithium disilicate crown. The DIC technique was performed to measure the deformation generated on the simulated bone surface (150 N loading). For the FEA (in silico), three-dimensional numerical models based on the in vitro setup were modeled using computer-aided design software. All materials were considered elastic, isotropic, and homogeneous. Comparison of both methods showed coherence between the in vitro and in silico results. The von-Mises stress of the implants, Ti base and screw, and the maximum principal stress in the mesostructure and crown were calculated for both conditions. Results: The overall surface deformation distributions determined by both techniques were considered similar allowing the model validation. The higher deformation was found in the cervical region with a higher magnitude for the angled hybrid abutment. The same pattern was observed in the stress fields regardless of the analyzed region and structure. Conclusion: Based on this study, using an angled hybrid abutment to correct the implant positioning generated higher stress in the implant fixture, surrounding tissue, Ti base, screw, and crown. Therefore, the implant should be positioned axially, whenever possible, to reduce the mechanical complications. Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNSEP) São José Dos Campos Department of Dentistry University of Taubaté (UNITAU), Taubaté Department of Dental Materials Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam Department of Dental Materials and Prosthodontics Institute of Science and Technology São Paulo State University (UNSEP) São José Dos Campos

Made available in DSpace on 2022-04-28T19:50:15Z (GMT). No. of bitstreams: 0 Previous issue date: 2022-01-01 Background: Orofacial injuries are common occurrences during contact sports activities. However, there is an absence of data regarding the performance of hybrid occlusal splint mouthguards (HMG), especially during compressive loading. This study amid to evaluate the biomechanical effects of wearing a conventional custom mouthguard (MG) or the HMG on the teeth, bone, and the device itself. Methods: To evaluate the total deformation and stress concentration, a skull model was selected and duplicated to receive two different designs of mouthguard device: one model received a MG with 4-mm thickness and the other received a novel HMG with the same thickness. Both models were subdivided into finite elements. The frictionless contacts were used, and a nonlinear analysis was performed simulating the compressive loading in occlusion. Results: The results were presented in von-Mises stress maps (MPa) and total deformation (mm). A higher stress concentration in teeth was observed for the model with the conventional MG, while the HMG design displayed a promising mechanical response with lower stress magnitude. The HMG design displayed a higher magnitude of stress on its occlusal portion (7.05 MPa) than the MG design (6.19 MPa). Conclusion: The hybrid mouthguard (HMG) reduced (1) jaw displacement during chewing and (2) the generated stresses in maxillary and mandibular teeth. Schulich School of Medicine & Dentistry Western University, 1151 Richmond St Department of Dental Materials Academic Centre for Dentistry Amsterdam (ACTA) University of Amsterdam and Vrije Universiteit Amsterdam Department of Dental Materials and Prosthodontics São Paulo State University (UNESP) Department of Dental Materials and Prosthodontics São Paulo State University (UNESP)

January 2023 started in a hurry to recover the time delayed by the pandemic and we would like to take this opportunity to wish you all a very happy new year to come. Before setting new goals and preparing new agendas for the current year, let’s take a step back and summarize last year’s pursuits that BDS Journal accomplished, the processes that were set, policies that were set, and goals that were defined to shape our successes in 2023. Last year the new publisher CUBO brought us a huge development in terms of speed and quality for our editorial process. It had its challenges and many wins. Let’s gather all the accomplishments that helped boost our spirit to do better each day including new rules such as: the change to continuous publication among the issues, new academic and assistant editors, new PDF configuration containing ORCID presented for each author, regulatory statement, the contribution of the authors. This noticeable improvement in our journal was only possible with weekly online meetings among the editors and the open access support through the new Article Processing Charge. The scientific community believed in our work and its contribution to our development was incredible. We published on time 95 papers amongst original articles, systematic reviews, critical reviews, case reports, short communications, and editorials [1-6]. The Annual Citescore index on SCOPUS database jumped from 0.3 to 1.5 (a growth of 5X), and we are now in the 77th position in the Dentistry field. To celebrate its Jubilee (25th anniversary) this year, BDS has just published a special issue with peer-reviewed papers from its editors and collaborators. Relishing success and learning from difficulties, we are even more motivated to create greater goals and objectives for ourselves with the mission of taking BDS journal to higher levels.

This study is aimed at evaluating the marginal microleakage of bulk-fill class II restorations after thermocycling. Thirty-two human third molars received class II cavities prepared on mesial and distal faces. The cavities were bonded according to the adhesive protocol (total or self-etching). The cavities were then restored with composite and divided into 8 groups based on the composite combination: layering technique with Filtek Z350XT (G1 and G5), first layer with Filtek Z350 XT Flowable Restorative and then Filtek Z350XT (G2 and G6), bulk-fill technique with Filtek One Bulk Fill (G3 and G7), and first layer with Filtek One Bulk Fill Flow and Filtek Z350 XT (G4 and G8). The restorations were then subjected to thermocycling (2000 cycles, 5°C and 55°C, dwell time of 30 s). After aging, the restored teeth were immersed in methylene blue for 48 hours. The restorations ( n = 32 ) were sectioned in the middle (two sections). The microleakage results were analyzed by two-way ANOVA followed by Tukey’s post hoc test ( α = 0.05 ). The groups did not differ statistically from each other in terms of marginal microleakage ( p = 0.295 ). It can be concluded that there is no difference in the percentage of microleakage between conventional and bulk-fill resins on both consistencies, as well as there is also no statistically significant difference when the adhesive system is used in a conventional or self-etching mode.

This study evaluated the effect of pH and temperature on the ion (F− and Ca2+) release of a resin-based material containing alkaline fillers and a self-setting high-viscous glass ionomer cement. Disks were prepared according to manufacturers’ instructions for both materials: the EF group (Equia Forte HT filling, GC) and the CN group (Cention N, Ivoclar). Specimens were immersed in 50 mL buffer solution with three different pHs (4.8, 6.8, and 8.8), and stored at 0°, 18°, 37°, and 44 °C. After 24 h, 7 d, and 28 d, cumulative F− and Ca2+ releases were analyzed by chromatography and mass spectrometry, and pH was measured. Both materials showed minimal changes in pH with final values after 28 d of 5.17 ± 0.56 for CN and 5.12 ± 0.24 for EF. In all experimental conditions, the percentages of ion release were higher for EF than for CF. In particular, both materials showed a significant difference in temperature in F− release. Regardless of the pH values, the highest Ca2+ ion release was after 28 days, with a significant difference in temperature for CN and EF. Within the limit of this study, the temperature storage influenced ion release and the high-viscous glass ionomer showed the maximum values.

Purpose: To compare the fit and clinical performance of screw-retained monolithic zirconia implant fixed dental prostheses (FDPs) fabricated based on either intraoral optical scanning (IOS) or conventional impressions. Materials and Methods: Patients with two posterior tissue-level implants (Regular Neck, Straumann) replacing two or three adjacent teeth were recruited. Impressions were taken with both IOS (True Definition Scanner, 3M Espe) and a conventional (polyether) pick-up impression. Double-blind randomization was performed after impression-taking, and patients were to receive an FDP based on either the digital or the conventional impression. The fit was evaluated, and the time required for adjustments was recorded. Additionally, survival and technical complication rates with a follow-up of 1 year were documented. Results: A total of 38 patients requiring 45 FDPs were included: 24 FDPs in the test (IOS) and 21 in the control (conventional) group. The average adjustment time was 6.92 minutes (SD: ± 10.84; range: 0 to 49) for digital vs 12.38 minutes (SD: ± 14.52, range: 0 to 54) for conventional impressions (P= .090). A proper fit (no adjustments) was achieved in 33.3% of the digital and 28.6% of the conventional group. Forty-two FDPs could be placed within the two planned appointments, and 3 FDPs exhibited an unacceptable fit and required an extra appointment. Eight technical complications occurred during the first year of function. The overall restoration survival rate was 100%. Conclusion: The clinical fit of CAD/CAM FDPs based on digital impressions is comparable to conventional impressions. Screw-retained monolithic zirconia FDPs on Ti-base abutments show low major complication and 100% survival rates in the short term. Int J Prosthodont 2021;34:733–743. doi: 10.11607/ijp.7074

Made available in DSpace on 2022-05-01T06:02:14Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Objectives: This study evaluated the effect of restoration occlusal design on the maximum fracture load and stress distribution of a feldspathic ceramic crown. Materials and Methods: Twenty dentin analogues were used to simulate a full-crown preparation. Next, 20 feldspathic crowns were milled according to the occlusal design parameter available in the CAD database (Young or Adult). The crowns were cemented with dual cure resin-cement and loaded until fracture at 1 mm/min crosshead speed. Data were analyzed by using one-way ANOVA and Tukey tests (p < 0.05). The same geometry and experimental setup was modeled and exported to the computer aided engineering software and tensile stress concentration was calculated using the finite element method with 300 N occlusal load simulation. Results: The occlusal anatomy significantly influenced the load-to-fracture (p < 0.05). Adult design showed higher mean values (1149 ± 201 N) than Young design (454 ± 77 N). The maximum principal stress criteria showed similar stress pattern for both designs, however, the highest stress concentration was calculated for Young design (91 MPa) in the occlusal surface. Conclusions: An anatomy design with reduced cusp angulation and less evident occlusal sulcus can reduce the stress concentration and increase the fracture load for feldspathic CAD/CAM posterior crowns. Department of Dental Materials and Prosthetics São Paulo State University (UNESP) Institute of Science and Technology Division of Dental Biomaterials Center for Dental and Oral Medicine Clinic for Reconstructive Dentistry University of Zurich Department of Dental Materials and Prosthetics São Paulo State University (UNESP) Institute of Science and Technology

Proper maxillomandibular relationship registration can be clinically challenging during a digital workflow in full-arch rehabilitations. This dental technique requires the manufacturing and use of a hybrid surgical guide custom scanning device, indicated to be used during implant placement surgery, in addition to being used to simultaneously register the maxillomandibular relationship and transfer the implants’ 3D positioning, ensuring a fully digital workflow in full-arch implant-supported prosthesis rehabilitation. The sequence of steps presented here will allow dentists and dental technicians to conduct rehabilitations from denture to the final implant-supported prosthesis using a full-digital protocol, using a minimal quantity of intraoral devices and digital tools.

This study aimed to investigate the effect of surface roughness (polished vs. CAD/CAM milling simulation) on impact strength of five dental ceramics for manufacturing CAD/CAM monolithic restorations. Specimens of five ceramics (FC- feldspathic glass-ceramic; PICN- polymer-infiltrated ceramic-network; ZLS- zirconia-reinforced lithium silicate glass-ceramic; LD- lithium disilicate glass-ceramic; YZ- yttria-stabilized tetragonal zirconia polycrystal ceramic) to be tested under impact (15×10×2mm3; n= 15) were divided into two groups, according to surface treatment: polishing (pol) and grinding (gri) as CAD/CAM milling simulation. Impact strength was tested using the Dynstat method. Roughness, topographic, fractographic and finite element analyses were performed. The impact strength data were analyzed by Weibull, and Pearson correlation was used to correlate roughness and impact strength data. The CAD/CAM milling simulation led to significantly (p

© 2021 Wiley Periodicals LLC.Objective: To evaluate the effect of surface treatments on optical, colorimetric, and surface characteristics of lithium disilicate glass–ceramic. Materials and Methods: Specimens (n = 5, IPS e.max CAD) were randomly allocated to the following treatments: mirror-polished: SiC papers; as-cut: mimicking CAD-CAM milling; ground: 90-120 μm-grit diamond bur; ground polished: ground, finished (46-30 μm-grit diamond bur), polished (diamond cups, brush and diamond paste); ground glazed: ground, glazed; ground polished glazed: association of methods. CIELAB color coordinates were obtained by a spectrophotometer. CIEDE2000 color differences (ΔE00) and the translucency parameter (TP00) were calculated. Light transmittance was assessed with a colorimeter. Surface characteristics (topography and roughness) were analyzed. Statistical differences for each condition and outcome were detected using one-way ANOVA with Tukey's post-hoc test (α = 0.05). Results: TP00 data show statistical reduction after grinding (p < 0.05), which was only restored with polishing (solely or with glazing). ΔE00 shows that grinding results in perceptible variations in color (above 0.81), which were restored after all post-processing protocols (exception to only glaze application in contact with a black background). Light transmittance data corroborated such performance. Polishing and glazing reduced roughness and improved surface topography. Conclusion: Grinding statistically increased roughness, reduced translucency, light transmittance through the ceramic, and resulted on color differences. On contrary, polishing (followed or not by glazing) reduced roughness and enhanced ceramic translucency and light transmittance. Glaze also reduced roughness, but it still presented reduced translucency. The positioning (facing up or down) of the ceramic treated surface influenced the considered outcomes. Clinical Significance: Grinding with diamond burs results in a deleterious impact to the optical, colorimetric and surface characteristics of lithium disilicate ceramic. Thus, polishing (followed or not by glazing) is recommended for optical and topographical enhancements when lithium disilicate monolithic restorations require occlusal adjustments.

This thesis aims to investigate a possible approach to increase the volume of the area in which augmentation material can be inserted under oral soft tissues with self-inflating osmotic soft tissue expanders. This then allows more augmentation material to be inserted. The properties of the augmentation material inserted, will have impact to the bone genesis. Therefore, bone morphogenetic protein 2 (BMP-2), which is known to be osteo-conductive and osteo-inductive, is studied. It is unclear whether there is bone formation when using BMP-2 in the treatment of peri-implantitis. The most effective dose BMP-2 to promote bone formation when using an osseo-conductive coralline hydroxyapatite (CHA) coated with an osseo inductive layer biomimetic calcium phosphate (BioCaP) is not clear yet. In order to describe the ideal properties of an expander for intra oral use, literature on tissue expanders used in general medicine was studied. Tissue expansion is indicated in cases where other surgical techniques aimed at gaining the soft tissue surface are inadequate. The use of tissue expanders requires extra time, extra surgical procedures, money and discomfort for the patient which limits its clinical use. The used self-inflating hydrogel Osmed ® expanders were enveloped in a silicone hull with a few small perforations, through which tissue fluids can be adsorbed by the hydrogel. Fixation of the expander, which is possible with a screw through the extension of the silicone envelope prevents dislocation. The histological findings showed no difference at comparing expanded and unexpanded tissue. The increase of the amount of soft tissue was clinically clearly visible, and no differences were found when following either the flap placement or the tunnel placement procedure. In a case report the use of two Osmed ® hydrogel soft tissue expanders enveloped in a silicone hull is described. A critical sized bone defect is too large to heal spontaneously. Bone augmentation procedures can be performed to overcome this. BMP-2 needs to have a carrier and a delivery mode to be an effective. As a carrier octa calcium phosphate (OCP) can be used. BMP-2 can be adsorbed in the outer layer of OCP: biomimetic calcium phosphate (BioCaP) with adsorbed BMP-2, or incorporated only in the outer layer of OCP: BioCaP with incorporated BMP-2, or BMP-2 can be incorporated throughout the entire layer of OCP: BioCaP with inserted BMP-2. The optimal dose BMP-2 to induce bone formation is unknown. Peri-implant bone defects can be considered as critical sized bone defects because they do not heal spontaneously. This study shows that when treating peri-implant bone defects in dogs with BioCaP containing adsorbed, incorporated or inserted BMP-2 they all generate bone. When BMP-2 has been incorporated in the entire volume of all BioCaP particles it performs the best. Hydroxyapatite is a main component of our skeleton. Marine coral is used as a natural bone graft material and has a trabecular structure comparable to bone. Through a hydrothermal process its calcium carbonate skeleton converses from coral to hydroxyapatite, thus forming coralline hydroxyapatite (CHA). CHA alone does not induce bone formation in an ectopic site. By coating CHA with BioCaP containing BMP-2 osteo-inductive properties could be added to the augmentation material. All CHA samples coated with BioCaP containing incorporated BMP-2 show bone formation in ectopic sites, whereby the sample containing 5 µg BMP-2 induces the most bone formation. It can be concluded that the tissue expanders looked promising but the research showed its limitations in volume increase, immediate expansion, costs involved and the extra surgery. BioCaP containing BMP-2 induces bone formation in animal studies in ectopic sites. The optimal BMP-2 concentrations per study are described.

© 2022 by the authors.This clinical report demonstrated the use of polyetheretherketone (PEEK) for manufacturing of custom-made post and core in weakened endodontically treated central incisors. The PEEK structure was manufactured using computer-aided design/computer-aided manufacturing (CAD/CAM). The optimal fit of this custom-made endodontic post allowed a thinner cement layer; and removed the need to manufacture a core build-up. While supplementary clinical trials and in vitro studies are needed to totally elucidate the advantages and limitations of PEEK as an option for post and core manufacturing, this case report showed that it can be promising for a predictable and simplified treatment with five years of success.

OBJECTIVES: To assess the cytotoxicity of an experimental hybrid-glass-based infiltrant and its effect on biofilm attachment, growth and metabolic activity, and to compare it to the resin-based infiltrant Icon.METHODS: Cytotoxicity of hybrid-glass-based material (EXP) and resin-based infiltrant Icon (Icon) was tested in direct contact tests on freshly cured (direct_mat) and on materials kept for 24 h in cell culture medium (direct_exmat), and extract test with materials 24-h extracts (extract). Cell viability of L929 mouse fibroblast cell line was measured with MTT assay, according to ISO10993-5:2009. Biofilm attachment (5 h), growth (24 h and 48 h) and lactic-acid production (24 h and 48 h) on glass-disk specimens coated with EXP or Icon, or uncoated (control), were assessed using a microcosm biofilm model and Amsterdam Active Attachment system. At indicated time points, biofilms were harvested, plated, and CFU counts were determined, while lactic-acid production was measured colorimetrically.RESULTS: Cell viability reduction by EXP was below 30%-threshold in direct contact tests, while in extract test an increased cell viability was observed. Icon reduced cell viability substantially in all three tests. Significantly less bacteria attached to the surface of EXP after 5 h compared to Icon and control. Biofilm growth was significantly lower on EXP than on Icon and control after 24 h, but this difference was smaller and statistically insignificant after 48 h. There was no difference in lactic-acid production among groups.SIGNIFICANCE: Novel hybrid-glass-based infiltrant seems to have a better biocompatibility and accumulates on its surface less bacteria than resin-based infiltrant, which makes it an attractive resin-free alternative.

The biomechanical behavior of the universal link (titanium base) prosthetic abutment with different heights in implant-supported restorations was evaluated. Forty regular implants (4 × 10 mm) in titanium were used, divided into two groups according to the abutment height (n = 20): 4.5 × 4 mm (short) and 4.5 × 5.5 mm (long). Using CAD/CAM technology, zirconia crowns were milled and cemented onto the prosthetic abutments. Half of the specimens were submitted to the initial maximum fracture load test in a universal testing machine. The long abutments presented fracture load (41.1 ± 6.96 kgf) statistically similar to the short abutments (49.5 ± 7.68 kgf). The other half of the specimens were submitted to mechanical cycling (2,000,000 cycles, 2 Hz with a stainless-steel antagonist with a diameter of 1.6 mm), following ISO 14801:2007. Subsequently, the survival of the specimens was evaluated using the survival analysis function, Kaplan–Meier and Mentel–Cox (log- rank) (p < 0.05). The finite element analysis was performed in similar conditions to those used for the in vitro test through computer-aided engineering software (version 19.2, ANSYS Inc., Houston, TX, USA). The biomechanical behavior of both models was similar regardless of the evaluated structure of the set. It was concluded that both short and long abutment presents promising fatigue behavior and stress distribution for use in long-term implant-supported restorations.

Statement of problem: When implants are applied to restore oral function, the masticatory load on the crown will lead to stress development in all parts of the crown-abutment-implant-bone system. An optimal design of the whole system will be important for sustained function. Purpose: The purpose of this 3-dimensional (3D) finite element analysis (FEA) study was to evaluate the influence of the root-analog implant (RAI) design in molar rehabilitation and bone type. Material and methods: Twelve 3D models of single posterior implant-supported restorations were created according to the zirconia implant design (monotype, 2-piece, or RAI) and bone type (D1, D2, D3, and D4, according to the Misch classification). The models were composed of cortical bone, cancellous bone, implant, cement layers, and a monolithic ceramic crown. For the 2-piece zirconia implant model, the titanium base, prosthetic screw, and framework were also designed. All materials were assumed to behave elastically throughout the entire analysis. The bone was fixed, and an axial loading of 600 N was applied to the contacts on the occlusal surface of the crowns. Results for the crown and implant were obtained in maximum principal stress, as well as the von Mises stress for the model and bone microstrain. Results: High stress concentration was observed at the intaglio surface of the crowns near the loading region. Regardless of the design, the stress trend in the implant was similar, increasing proportionally to the bone type (D1>D2>D3>D4). RAI showed a homogeneous stress field near the values calculated for the conventional designs, but with lower magnitudes. The 2-piece zirconia model showed the highest stress magnitude regardless of the bone type and, therefore, the highest failure risk. All models showed a higher strain in the cortical bone than in the cancellous bone, located predominantly in the cervical region. A strain analysis showed that both conventional implant models presented similar behavior for D1 and D2 bone types, with an increasing difference for D3 and D4. RAI showed the lowest strain regardless of the bone type. Conclusions: Root-analog zirconia implants present a promising biomechanical behavior for dissipating the masticatory load in comparison with conventional screw-shaped implants.

Objective: To evaluate the fatigue behavior of lithium disilicate crowns with a simplified anatomy against progressive cement/ceramic debonding scenarios. Materials and methods: Lithium disilicate crowns were fabricated via CAD/CAM and luted onto a dentin analogue material using resin cement following the manufacturer's instructions. Then, the different crown regions were isolated with paraffin oil for the absence of chemical adhesion according to four experimental groups (n = 15): Shoulder; Shoulder + Axial; Fully isolated; and Control (no insulation/fully bonded). Load to failure tests (n = 3) were run to determine cyclic fatigue parameters, and the specimens were subsequently submitted to a cyclic fatigue test (n = 12) (initial load 200 N for 5000 cycles, step 100 N, 15,000 cycles/step, frequency 20 Hz) until cracks were observed, and later fracture. The data were analyzed by Kaplan-Meier + Mantel-Cox post-hoc tests for both outcomes (cracks and fracture). Fractographic, cross-sectional surface, and finite element (FEA) analyzes were performed. Results: When it comes to crack occurrence when the chemical adhesion to the occlusal surface is compromised, there is worsening (p < 0.05) in fatigue behavior compared to groups where the occlusal portion of the crown is still bonded. Considering fracture occurrence, there was no difference (p > 0.05) among the tested groups. All cracks occurred in the occlusal portion, first as a radial crack at the ceramic intaglio surface, and posteriorly unleashing a Hertzian cone crack at the top surface, resulting in fractures on the frontal walls. The interface analysis showed no interference of the insulating agent. FEA showed that as the isolated areas increased, there was also an increase in both tensile and shear stresses concentration in the crown and in the cement layer. Conclusion: The chemical adhesion between cement and ceramic is essential for better fatigue behavior of lithium disilicate crowns with a simplified anatomy, especially in the occlusal portion, but the restoration performance is impaired when such adhesion is compromised. There is an increase in crown and cement stress concentration with the progressive loss of chemical bonding of the crown's walls.

BackgroundTo investigate human oral health and disease, models are required which represent the interactions between the oral mucosa and microbiome. Our aim was to develop an organotypic model which maintains viability of both host and microbes for an extended period of time.MethodsReconstructed Human Gingiva (RHG) were cultured air-lifted with or without penicillin-streptomycin (PS) and topically exposed to Streptococcus gordonii (commensal) or Aggregatibacter actinomycetemcomitans (pathogen) for 72 hours in agar. RHG histology, viability and cytokines (ELISA), and bacterial viability (colony forming units) and location (FISH) were assessed.ResultsThe low concentration of topically applied agar did not influence RHG viability. Topically applied bacteria in agar remained localized and viable for 72 hours and did not spill over to infect RHG culture medium. PS in RHG culture medium killed topically applied bacteria. Co-culture with living bacteria did not influence RHG viability (Ki67 expression, MTT assay) or histology (epithelium differentiation, Keratin10 expression). RHG exposed to S. gordonii (with or without PS) did not influence low level of IL-6, IL-8, CCL2, CCL5, CCL20 or CXCL1 secretion. However, all cytokines increased (except CCL2) when RHG were co-cultured with A. actinomycetemcomitans. The effect was significantly more in the presence of living, rather than dead, A. actinomycetemcomitans. Both bacteria resulted in increased expression of RHG antimicrobial peptides (AMPs) Elafin and HBD-2, with S. gordonii exposure resulting in the most Elafin secretion.ConclusionThis technical advance enables living human oral host–microbe interactions to be investigated during a 72-hour period and shows differences in innate immunology triggered by S. gordonii and A. actinomycetemcomitans.

The aim of the study was to evaluate whether the region (internal or external) of the CAD/CAM block influences the mechanical performance of restorative materials. Blocks of different CAD/CAM materials (Composites: KAV – Katana Avencia; LULT – LULT Ultimate; Ceramics: ENAM – Vita Enamic; NICE - N!CE; EMP – IPS Empress CAD; VMII – Vita Mark II; EMAX – IPS e.max CAD) were selected, and direct resin composite blocks (APX - Clearfil AP-X; FSUP - Filtek Supreme) were built using the incremental technique on a mold from one of the CAD/CAM blocks. All blocks were sectioned into bar-shaped specimens (1 × 1 × 14 mm), which were separated into two groups according to the region of the block (inside or outside). 3-point bending tests were performed following ISO 6872:2015 and flexural strength data were analyzed using one-way ANOVA and Bonferroni post-hoc tests (p < 0.05). Weibull module and characteristic strength were also calculated. In general, the mean flexural strength values were not statistically different (p > 0.05) between the inside and outside regions of each material, except for LULT (inside > outside) and EMAX (outside > inside). Comparing the materials, a similar strength (only discrete variations) was observed for inside, outside or merged (inside and outside data assembled together) regions: EMAX > KAV = LULT > NICE = APX > EMP = ENAM = VMII ≥ FSUP (merged condition). Characteristic strength at 63.2% failure probability and at 5% failure probability generally corroborates such observations. There were no statistical differences for Weibull module data (inside, outside, or merged), except for KAV and NICE (outside > inside). Thus, the region from where the restoration is milled within the CAD/CAM block generally does not influence the mechanical performance hereof (flexural strength, failure probability, risk of premature failures, and mechanical reliability) of the material, except for LULT and EMAX.

Objectives: The evaluation of three different drug delivery modes of bone morphogenetic protein-2 (BMP-2) in healing peri-implant bone defects in beagle dogs. BMP-2 was incorporated in or onto calcium phosphate (CaP) granules in various ways: (i) directly on the outer layer of granules CaP: as an adsorbed depot; (ii) during the entire precipitation process of CaP: an internally incorporated depot; or (iii) during the biomimetic coating precipitation of BMP-2 on the surface of CaP granules: as a coating incorporated depot. Material and Methods: After extraction of the lower molars and wound healing in 6 male beagle dogs, 36 implants were placed (n = 6 animal per group). Peri-implant bone defects were induced. The following treatment groups were evaluated: no treatment; air abrasive surface cleaning (SC) using hydroxyapatite; SC and the subsequent filling of the defect with CaP without BMP-2; SC plus the subsequent filling of the defect with CaP adsorbed BMP-2; SC plus the subsequent filling of the defect with CaP internally incorporated BMP-2; SC plus the subsequent filling of the defect with CaP coating incorporated BMP-2. Histological and histomorphometric analyses were carried out to quantify and compare the changes in bone tissue surrounding the treated implants. Results: In Group 1 with no treatment, four implants were lost. Group 5 with the SC and the subsequent filling of the defect with internally incorporated BMP-2 biomimetically prepared CaP (BioCaP), whereby the BMP-2 is incorporated in the entire volume of all BioCaP particles, showed overall the best results to regenerate bone around the implants. Conclusion: This study concluded that the group treated with SC plus the subsequent filling of the defect with CaP BMP-2 internally incorporated BMP-2, whereby BMP-2 has been incorporated in the entire volume of all CaP particles, showed overall the best results when aiming to regenerate bone around the implants.

Objectives: The aim of this study was to compare the effect of three different access cavities on the tissue removal, deflection, fracture resistance, and stress distribution of extracted maxillary central incisors. Materials and methods: Forty human maxillary central incisors were randomly assigned in four experimental group (n = 10) including conservative access cavity “CAC,” traditional access cavity “TAC,” invasive access cavity “IAC,” and without access cavity (control group). Cone-beam computed tomography “CBCT” scans were used to evaluate the tissue removal during the different access cavities. All specimens were restored with composite resin (Admira Fusion, Voco, Cuxhaven, Germany) and embedded in acrylic resin blocks after simulating the periodontal ligament using red wax, then the specimens were submitted to the deflection test applying a load of 250 N and to the load-to-fracture test after artificial aging in a mechanical cycling machine (150 N, 5 × 106 cycles, 10 Hz). Lastly, stress distribution was assessed by three-dimensional finite element analysis (3D-FEA), simulating the specimens restoration by two types of composite resins of low and high elastic modulus (8 and 18 GPa respectively) after the access cavities. The data were submitted to Shapiro–Wilk and KS normality tests. Then, they were analyzed by one-way ANOVA and Tukey tests with a significance level (α ≤ 0.05). Results: CBCT scans showed a significant difference of worn tissues in CAC and TAC when compared to the IAC (P < 0.0001). In deflection test, CAC showed lower deformation values than the TAC and IAC. Load-to-fracture test presented no significant difference among the three experimental groups (P = 0.6901). 3D-FEA showed that the more conservative the access cavity, the higher the stress magnitude. Conclusions: CAC promote less worn tissue; however, this does not improve the stress distribution or fracture resistance of endodontically treated maxillary incisors. Clinical relevance: Clinicians should reconsider the pros and cons of the conservative access cavity.

Made available in DSpace on 2021-06-25T10:54:04Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-01-01 Investigate the tensile bond strength, surface morphology, and wettability of reinforced glass-ceramic etched with high power laser at different protocols and luted to human dentin. Fifty carious-free human molars were used in this study and distributed in five groups according to surface etching: (Control [HF10% + Silane]; Er [Er:YAG + Silane]; Sil + Er [Silane + Er:YAG]; Nd [Nd:YAG + Silane]; and Nd + Sil [Silane + Nd:YAG]). After, the tensile bond strength test was performed. Three specimens per group were used to perform the surface morphologies by using scanning electron microscopy analysis and wettability by using the sessile drop technique. Failure modes were determined. Data were analyzed with two-way analysis of variance and Tukey tests, with α =.05. The bond strength data showed statistically significant differences among tested groups for the laser and silanization technique type (p

Made available in DSpace on 2022-05-01T10:18:56Z (GMT). No. of bitstreams: 0 Previous issue date: 2021-06-01 Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) Background. The present study aimed to evaluate the influence of the veneering technique on the tensile stress distribution and survival of full-ceramic fixed dental prostheses (FDPs). Methods. A three-dimensional model of an FDP was modeled on a second premolar and a second molar with a pontic between them for finite element analysis (FEA). The groups were divided according to the veneering technique: conventional stratification, rapid layer, and CAD-on techniques. A mesh control test determined the number of elements and nodes. The materials’ properties were attributed to each solid component with isotropic, homogeneous, and linear elastic behavior. For the in vitro fatigue test (n = 30), the FDPs were cemented on dentin analog abutments and submitted to 2×106 mechanical cycles (100 N at 3 Hz). Results. Maximum principal stress showed that the connector between the pontic and the second molar concentrated higher stresses, regardless of the techniques: Rapid layer (6 MPa) > CAD-on (5.5 MPa) > conventional stratification (4 MPa). The conventional stratification technique concentrated high stresses at the interface between the framework and veneering ceramic (2 MPa), followed by the rapid layer (1.8 MPa) and CAD-on (1.5 MPa) techniques. The crowns fabricated using the rapid layer and CAD-on techniques exhibited a 100% survival rate, while the conventional stratification group had 0% survival. Conclusion. Even with similar stress distribution between the veneering techniques, the conventional stratification technique was more prone to failure under fatigue due to higher defects incorporated than CAD-on and rapid layer techniques. Department of Dental Materials and Prosthodontics São Paulo State University Institute of Science and Technology Department of Dental Materials and Prosthodontics São Paulo State University Institute of Science and Technology FAPESP: 12/11095-0 FAPESP: 14/00668-4

Oral hard tissue refers to the hard and mineralized tissues, such as enamel, dentin, and bone, which form an integral complex, playing a vital role in aesthetics and oral functions. The osteochondral complex of temporomandibular joint (TMJ) also functions to dissipate or transfer the masticatory force. In this thesis, we mainly focused on the regeneration of dentin, bone and osteochondral complex by using functionalized hydrogels. In chapter 2, we developed injectable colloidal gels through a simple UV method from methacrylic acid functionalized gelatin (Gel-MA) loaded with notoginsenoside R1 (Gel-MA/NGR1) for reparative dentin regeneration. Our results showed that the hydrogel retained porous inner structure and hydrophilicity with a sustained drug release. Gel-MA/NGR1 hydrogel could significantly promote in-vitro dentinogenic markers, extracellular matrix mineralization, and in-vivo reparative dentin formation in comparison with Gel-MA. These findings suggested a promising application potential of Gel-MA/NGR1 in pulp-capping techniques. The avascular structure and lack of regenerative cells make the repair of osteochondral defects in the TMJ highly challenging in clinic. To provide a viable treatment option, in chapter 3, we developed a histatin-1 (Hst1)-functionalized Gel-MA hydrogel to combine the chondroconductive property of Gel-MA and the cell-activating capacity of Hst1 to repair the critical-size osteochondral defects in TMJ. Our data showed that Hst1/Gel-MA hydrogel group possessed a significant higher International Cartilage Repair Society (ICRS) score and Modified O‘Driscoll Score (MODS) in comparison with the Gel-MA group and control group. Furthermore, histomorphometric analysis showed significantly higher expression of collagen II, aggrecan, collagen fiber, GAG, and more newly formed subchondral bone and cartilage in Hst1/Gel-MA hydrogel group than the Gel-MA group and control group. The usage of Gel-MA may not be very suitable for the partially exposed defects, such as, jumping gap in immediate implantation since the long and narrow geometry of, and the bleeding in jumping gap may largely hinder the photocrosslinking-based gelation process and lead to insufficient gelation. To approach this situation, we resorted to another type of hydrogel — injectable self-healing hydrogels with dynamic crosslinking, which could be gelled without the needs of additional chemical/physical initiations. In chapter 4, we adopted gelatin and oxidized alginate (OSA) to construct an injectable self-healing hydrogel. The physicochemical and in-vitro and in-vivo biological characterization showed that the self-healing hydrogels could support cell survival, proliferation, and migration, and had a good injectability, in-situ gelation, and biocompatibility, suggesting a promising candidate for tissue engineering scaffold and drug delivery vehicle. In comparison with conventional osteconductive CaP-based bone filling materials, an injectable, self-healing and pro-osteogenic hydrogel will be more suitable to fill large jumping gap and preserve buccal bone. In chapter 5, we developed an injectable self-healing sericin/oxidized alginate hydrogel (SS/OSA), and functionalized the hydrogel with a pro-osteogenic agent ―salvianolic acid B (SAB). The results suggested that the SS/OSA-SAB hydrogel might be a promising scaffold candidate for promoting bone regeneration in jumping gaps. Barrier membrane is an indispensable element in GBR technique to prevent the invasion of surrounding connective tissues that bears proliferation advantage over osteoblasts so as to facilitate bone tissue regeneration. Gel-MA bears certain stickiness to mineralized tissue and UV crosslinking is also very suitable for this application. However, the mechanical property of Gel-MA should still be improved to be used as a GBR membrane. In chapter 6, we adopted a hybrid-crosslinking method (Schiff’s base reaction and UV initiated polymerization) to develop an in-situ formed barrier membrane with enhanced mechanical property and osteogenesis. In this thesis, we adopted different bioactive agents or ECM components to functionalize hydrogels with enhanced mechanical and pro-osteogenic/dentinogenic properties. These data suggested a promising potential of the functionalized hydrogels in the regeneration of oral hard tissues.

Purpose: To evaluate the effect of irradiation with an optical-fiber device on the bond strength of hollow and partially opaque intraradicular posts. Materials and Methods: An optical-fiber accessory tip was attached to a light-curing unit to emit light through the central hollow of an experimental fiberglass post. The samples were divided into 4 groups (n=80) according to the protocol (Variolink N [light cured] or Multilink N [dual-curing luting material]) and the light-curing mode (performed con ventionally or with the optical fiber): GF: light-curing luting material; GFF: light-curing luting material and optical fiber; GD: dual-curing luting material; GDF: dual-curing luting material and optical fiber. The samples were tested immedi ately or after aging. Push-out bond strength, failure mode, degree of conversion (DC, assessed at the peak of 1750cm-1), and stress distribution by finite element analysis were performed. Quantitative data were analyzed using 3-way ANOVA (luting material x light curing x depth) and 2-way ANOVA (aging x luting material), followed by Tukey’s test. Results Bond strength was significantly affected by the luting material protocol (p

The repair of large bone defects remains challenging due to the respective limitations of the clinically available bone grafts. Therefore, continuous efforts have been made to develop new bone and periosteum substitutes to enhance bone regeneration. HUCMSCs are promising stem cells for bone tissue engineering. However, a series of in-vitro studies have shown that the osteogenic efficacy of hUCMSCs is relatively lower than that of BMSCs. Therefore, in Chapter 2, we adopted a biomimetic strategy of co-culturing osteogenically- and angiogenically-committed hUCMSCs in various mixing ratios and culture media to promote the osteogenic efficacy of hUCMSCs. Compared with mono-cultured osteogenically-committed hUCMSCs in OM, a 3:1 ratio of osteogenically- and angiogenically-committed cells co-cultured in a 3:1 ratio of osteogenic medium and endothelial cell induction medium bore dramatically higher osteogenic properties, thus providing a novel strategy to fabricate hUCMSC-based biomimetic BTE constructs with enhanced osteogenic efficacy. It is established that ECM hydrogels bear a tissue-specific induction property. Therefore, in Chapter 3, decellularized periosteum-derived hydrogels (dPH) were fabricated and compared with the non-periosteum/bone-specific ECM hydrogel, Matrigel. Our study showed dPH exhibited a prominent effect on promoting the initial cellular spreading, migration, and proliferation. Moreover, the dPH group was associated with the enhanced osteogenesis-related genes expression and mineralized matrix formation of hUCMSCs than that of Matrigel. Our study indicated a promising application potential of biomimetic hUCMSCs/dPH constructs to repair bone defects. BioCaP coating has long been used to confer bone constructs an osteoconductive surface and enhanced scaffold-cell interactions. However, its biomedical application is limited by the low coating yield efficiency and protein-incorporation rate of the current coating procedure using 1× supersaturated CaP solution (SCPS). Therefore, in Chapter 4, we developed a highly concentrated 4.5× SCPS solution to harvest BioCaP coating. The thereby produced coating bore several advantages over the original coating, such as a higher coating yield efficiency and protein-incorporating rate. The new coating was identified as DCPD/apatite crystalline and showed a strong acid-resistant property. These properties conferred the new coating a promising potential in the functionalization of titanium implants for biomedical applications. Polydopamine (pDA) coating is a simple and effective method to modify scaffolds, thus covalently immobilizing growth factors and increasing surface bioactivity. Whether 3D printed TCP scaffolds functionalized by pDA-immobilized BMP2 were superior in prefabricating biomimetic bone grafts than the scaffolds functionalized by the superficially adsorbed one in latissimus dorsi muscle remained to be studied. Therefore, in Chapter 5, pDA-coated TCP (TCP/pDA) scaffolds were fabricated and characterized. Our study demonstrated that pDA coating was an efficacious method to improve the loading efficacy of BMP2 on the scaffolds, which also ensured a slow release profile of the loaded BMP2. Besides, pDA-immobilized BMP2 significantly promoted the osteogenic differentiation of C2C12 and the in-vivo bone formation. Our data suggested that the 3D printed TCP scaffolds functionalized with pDA-immobilized BMP2 were promising to prefabricate biomimetic bone grafts for repairing large bone defects. The development of tissue-engineered periosteum (TEP) is a promising strategy to accelerate the repair of bone defects. However, the previously developed TEPs lack periosteum-specific niches to regulate cellular activities and are hard to realize genuine biomimetic periosteum in composition. Therefore, in Chapter 6, we adopted the co-axial electrospinning technique to fabricate a novel biomimetic TEP with PCL-core/dECM-shell-structured microfibers. The novel PEC resembled the mechanical strength of the PCL membrane and bore dECM-like hydrophilicity and bioactivity to promote cell spreading, proliferation, and osteogenic activities. Moreover, PEC bore a comparable healing efficacy in repairing bone defects to the pure ECM, which was significantly higher than that in the pure PCL membrane. These findings indicated a promising application potential of the novel PEC-TEP in repairing bone defects.

Objectives: Mandibular retromolar (predominantly cortical) and maxillary tuberosity (predominantly cancellous) bone grafts are used in patients undergoing maxillary sinus floor elevation (MSFE) for dental implant placement. The aim of this retrospective cohort study was to investigate whether differences exist in bone formation and vascularization after grafting with either bone source in patients undergoing MSFE. Methods: Fifteen patients undergoing MSFE were treated with retromolar (n = 9) or tuberosity (n = 6) bone grafts. Biopsies were taken 4 months postoperatively prior to dental implant placement, and histomorphometrically analyzed to quantify bone and osteoid area, number of total, apoptotic, and receptor activator of nuclear factor-κB ligand (RANKL)-positive osteocytes, small and large-sized blood vessels, and osteoclasts. The grafted area was divided in three regions (caudal-cranial): RI, RII, and RIII. Results: Bone volume was 40% (RII, RIII) higher and osteoid volume 10% (RII) lower in retromolar compared to tuberosity-grafted areas. Total osteocyte number and number of RANKL-positive osteocytes were 23% (RII) and 90% (RI, RII) lower, but osteoclast number was higher (retromolar: 12, tuberosity: 0) in retromolar-grafted areas. The total number of blood vessels was 80% (RI) to 60% (RIII) lower, while the percentage of large-sized blood vessels was 86% (RI) to 25% (RIII) higher in retromolar-grafted areas. Number of osteocyte lacunae and apoptotic osteocytes were similar in both bone grafts used. Conclusions: Compared to the retromolar bone, tuberosity bone showed increased bone vitality and vascularization in patients undergoing MSFE, likely due to faster bone remodeling or earlier start of new bone formation. Therefore, tuberosity bone grafts might perform better in enhancing bone regeneration.

This study aimed to evaluate the biomechanical behavior of Morse taper implants using different abutments (CMN abutment [(CMN Group] and miniconical abutments [MC Group]), indicated to support a screw-retained 3-unit fixed partial denture. For the in vitro test, polyurethane blocks were fabricated for both groups (n = 10) and received three implants in the “offset” configuration and their respective abutments (CMN or MC) with a 3-unit fixed partial denture. Four strain gauges were bonded to the surface of each block. For the finite element analysis, 3D models of both groups were created and exported to the analysis software to perform static structural analysis. All structures were considered homogeneous, isotropic, and elastic. The contacts were considered non-linear with a friction coefficient of 0.3 between metallic structures and considered bonded between the implant and substrate. An axial load of 300 N was applied in three points (A, B, and C) for both methods. The microstrain and the maximum principal stress were considered as analysis criteria. The obtained data were submitted to the Mann–Whitney, Kruskal–Wallis, and Dunn’s multiple comparison test (α = 5%). The results obtained by strain gauge showed no statistical difference (p = 0.879) between the CMN (645.3 ± 309.2 με) and MC (639.3 ± 278.8 με) and allowed the validation of computational models with a difference of 6.3% and 6.4% for the microstrains in the CMN and MC groups, respectively. Similarly, the results presented by the computational models showed no statistical difference (p = 0.932) for the CMN (605.1 ± 358.6 με) and MC (598.7 ± 357.9 με) groups. The study concluded that under favorable conditions the use of CMN or MP abutments to support a fixed partial denture can be indicated.