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Biomimetics is the science of imitating nature's designs and processes to create innovative solutions for various fields, including dentistry and craniofacial reconstruction. In these areas, biomimetics involves drawing inspiration from living organisms/systems to develop new materials, techniques, and devices that closely resemble natural tissue structures and enhance functionality. This field has successfully demonstrated its potential to revolutionize craniofacial procedures, significantly improving patient outcomes. In dentistry, biomimetics offers exciting possibilities for the advancement of new dental materials, restorative techniques, and regenerative potential. By analyzing the structure/composition of natural teeth and the surrounding tissues, researchers have developed restorative materials that mimic the properties of teeth, as well as regenerative techniques that might assist in repairing enamel, dentin, pulp, cementum, periodontal ligament, and bone. In craniofacial reconstruction, biomimetics plays a vital role in developing innovative solutions for facial trauma, congenital defects, and various conditions affecting the maxillofacial region. By studying the intricate composition and mechanical properties of the skull and facial bones, clinicians and engineers have been able to replicate natural structures leveraging computer-aided design and manufacturing (CAD/CAM) and 3D printing. This has allowed for the creation of patient-specific scaffolds, implants, and prostheses that accurately fit a patient's anatomy. This review highlights the current evidence on the application of biomimetics in the fields of dentistry and craniofacial reconstruction. [ABSTRACT FROM AUTHOR]

This study evaluated how implant design features influence osseointegration. Two implant macrogeometries and surface treatments were evaluated: (1) progressive buttress threads with an SLActive surface (SLActive/BL), and (2) inner and outer trapezoidal threads with a nanohydroxyapatite coating over a dual acid-etched surface (Nano/U). Implants were placed in the right ilium of 12 sheep, and histologic and -metric analyses were conducted after 12 weeks. Percentages of bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO) within the threads were quantified. Histologically, the SLActive/BL group showed greater and more intimate BIC than the Nano/U group. In contrast, Nano/U group depicted woven bone formation within the healing chambers, between the osteotomy wall and implant threads, and bone remodeling was evident at the outer thread tip. Significantly higher BAFO was seen in the Nano/U group than the SLActive/BL group at 12 weeks (P < .042). Different implant design features influenced the osseointegration pathway, supporting further investigations to describe the differences and clinical performance. [ABSTRACT FROM AUTHOR]

Osseodensification enhances the stability of endosteal implants. However, pre-clinical studies utilizing osseodensification instrumentation do not account for the limited presence of trabeculae seen clinically. This study aimed to evaluate the effect of osseodensification instrumentation on osteotomy healing in scenarios with and without the presence of trabecular bone. A ~10 cm incision was made over the hip of twelve sheep. Trabecular bone was surgically removed from twelve sites (one site/animal; negative control (Neg. Ctrl)) and left intact at twelve sites (one site/animal; experimental group (Exp.)). All osteotomies were created using the osseodensification drilling protocol. Each osteotomy received an endosteal implant and was evaluated after 3 or 12 weeks of healing (n = 6 animals/time). Histology revealed increased woven and lamellar bone surrounding the implants in the Exp. group relative to the Neg. Ctrl group. The Exp. group demonstrated the presence of bone fragments, which acted as nucleating sites, thereby enhancing the bone formation and remodeling processes. Bone-to-implant contact (%BIC) and bone area fractional occupancy (%BAFO) were significantly higher in the Exp. group relative to the Neg. Ctrl group both at 3 weeks (p = 0.009 and p = 0.043) and 12 weeks (p = 0.010 and p = 0.008). Osseodensification instrumentation in the presence of trabecular bone significantly improved osseointegration. However, no negative influences such as necrosis, inflammation, microfractures, or dehiscence were observed in the absence/limited presence of trabeculae. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the reliability and failure modes of ultrathin (0.5 mm) lithium disilicate, translucent and ultra‐translucent zirconia crowns for posterior teeth restorations. Materials and Methods: Fifty‐four mandibular first molar crowns of three ceramic materials: (1) Lithium disilicate (e.max CAD, Ivoclar Vivadent), (2) 3Y‐TZP (Zirconn Translucent, Vipi), and (3) 5Y‐PSZ (Cercon XT, Dentsply Sirona), with 0.5 mm of thickness were milled and cemented onto composite resin abutments. Eighteen samples of each group were tested under mouth‐motion step‐stress accelerated life testing in a humid environment using mild, moderate, and aggressive profiles. Data was subjected to Weibull statistics. Use level curves were plotted and reliability was calculated for a given mission of 100,000 cycles at 100, 200, and 300 N. Fractographic analyses of representative samples were performed in scanning electron microscope. Results: Beta (β) values suggest that failures were dictated by material's strength for lithium disilicate and by fatigue damage accumulation for both zirconias. No significant differences were detected in Weibull modulus and characteristic strength among groups. At a given mission of 100,000 cycles at 100 N, lithium disilicate presented higher reliability (98% CB: 95–99) regarding 3Y‐TZP and 5Y‐PSZ groups (84% CB: 65%–93% and 79% CB: 37&–94%, respectively). At 200 N, lithium disilicate reliability (82% CB: 66%–91%) was higher than 5Y‐PSZ (20% CB: 4%–44%) and not significantly different from 3Y‐TZP (54% CB: 32%–72%). Furthermore, at 300 N no significant differences in reliability were detected among groups, with a notable reduction in the reliability of all materials. Fractographic analyses showed that crack initiated at the interface between the composite core and the ceramic crowns due to tensile stress generated at the intaglio surface. Conclusions: Ultrathin lithium disilicate crowns demonstrated higher reliability relative to zirconia crowns at functional loads. Lithium disilicate and zirconia crown's reliability decreased significantly for missions at higher loads and similar failure modes were observed regardless of crown material. The indication of 0.5 mm thickness crowns in high‐load bearing regions must be carefully evaluated. Clinical Significance: Ultraconservative lithium disilicate and zirconia crowns of 0.5 mm thickness may be indicated in anterior restorations and pre‐molars. Their clinical indication in high‐load requirement regions must be carefully evaluated. [ABSTRACT FROM AUTHOR]

This in vivo study evaluated the bone healing response around endosteal implants with varying surface topography/chemistry in a preclinical, large transitional model induced with metabolic syndrome (MS) and type‐2 diabetes mellitus (T2DM). Fifteen Göttingen minipigs were randomly distributed into two groups: (i) control (normal diet, n = 5) and (ii) O/MS (cafeteria diet for obesity induction, n = 10). Following obesity induction, five minipigs from the obese/metabolic syndrome (O/MS) group were further allocated, randomly, into the third experimental group: (iii) T2DM (cafeteria diet + streptozotocin). Implants with different surface topography/chemistry: (i) dual acid‐etched (DAE) and (ii) nano‐hydroxyapatite coating over the DAE surface (NANO), were placed into the right ilium of the subjects and allowed to heal for 4 weeks. Histomorphometric evaluation of bone‐to‐implant contact (%BIC) and bone area fraction occupancy (%BAFO) within implant threads were performed using histomicrographs. Implants with NANO surface presented significantly higher %BIC (~26%) and %BAFO (~35%) relative to implants with DAE surface (%BIC = ~14% and %BAFO = ~28%, p <.025). Data as a function of systemic condition presented significantly higher %BIC (~28%) and %BAFO (~42%) in the control group compared with the metabolically compromised groups (O/MS: %BIC = 14.35% and %BAFO = 26.24%, p <.021; T2DM: %BIC = 17.91% and %BAFO = 26.12%, p <.021) with no significant difference between O/MS and T2DM (p >.05). Statistical evaluation considering both factors demonstrated significantly higher %BIC and %BAFO for the NANO surface relative to DAE implant, independent of systemic condition (p <.05). The gain increase of %BIC and %BAFO for the NANO compared with DAE was more pronounced in O/MS and T2DM subjects. Osseointegration parameters were significantly reduced in metabolically compromised subjects compared with healthy subjects. Nanostructured hydroxyapatite‐coated surfaces improved osseointegration relative to DAE, regardless of systemic condition. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the effect of different hydrofluoric acid concentrations and etching times on the surface, chemical composition and microstructure of lithium disilicate. Material and Methods: Ninety specimens of pressed lithium disilicate (LDS) were obtained (IPS e.max Press, Rosetta SP and LiSi Press). The specimens of each material were divided in two groups according to the hydrofluoric acid concentration: 5% and 10% (n = 15/group), and subdivided according to the etching time: 20, 40 and 60 s (n = 5/group). Crystalline evaluations and chemical composition were performed through x‐ray diffraction (XRD) and energy‐dispersive x‐ray spectroscopy (EDS), respectively. Microstructural analyses were performed by scanning electron microscope (SEM), surface roughness (Ra), and material thickness removal evaluation. Thickness removal and Ra data were analyzed by ANOVA and Tukey test (p < 0.05). Results: XRD demonstrated characteristic peaks of lithium disilicate crystals, lithium phosphate and of a vitreous phase for all materials. EDS identified different compositions and SEM confirmed different surface responses to acid etching protocols. Material and etching time influenced Ra and material thickness removal (p < 0.05). Conclusion: Hydrofluoric acid concentration and etching time affect the surface characteristics of LDS differently. LiSi Press presented higher resistance to hydrofluoric acid etching compared to e.max Press and Rosetta SP. Clinical Significance: Applying the appropriate etching protocol is pivotal to avoid excessive material removal and to prevent jeopardize the mechanical and optical properties of the material. [ABSTRACT FROM AUTHOR]

Dental zirconias have been broadly utilized in dentistry due to their high mechanical properties and biocompatibility. Although initially introduced in dentistry as an infrastructure material, the high rate of technical complications related to veneered porcelain has led to significant efforts to improve the optical properties of dental zirconias, allowing for its monolithic indication. Modifications in the composition, processing methods/parameters, and the increase in the yttrium content and cubic phase have been presented as viable options to improve zirconias' translucency. However, concerns regarding the hydrothermal stability of partially stabilized zirconia and the trade-off observed between optical and mechanical properties resulting from the increased cubic content remain issues of concern. While the significant developments in polycrystalline ceramics have led to a wide diversity of zirconia materials with different compositions, properties, and clinical indications, the implementation of strong, esthetic, and sufficiently stable materials for long-span fixed dental prostheses has not been completely achieved. Alternatives, including advanced polycrystalline composites, functionally graded structures, and nanosized zirconia, have been proposed as promising pathways to obtain high-strength, hydrothermally stable biomaterials. Considering the evolution of zirconia ceramics in dentistry, this manuscript aims to present a critical perspective as well as an update to previous classifications of dental restorative ceramics, focusing on polycrystalline ceramics, their properties, indications, and performance. [ABSTRACT FROM AUTHOR]

To assess the influence of dentifrices with different abrasiveness levels on the properties of dental reconstructive materials. Forty-eight cylinders were obtained from four polymeric materials, being two CAD/CAM acrylic resins (Ivotion-Dent and Ivotion-Base), one injected acrylic resin (IvoBase-Hydrid) and one light-cured resin composite (Empress Direct). Specimens were allocated to four subgroups for toothbrushing simulation according to the dentifrice relative dentin abrasivity (RDA) and silica content: (i) RDA 0 = 0%; (ii) RDA 50 = 3%; (iii) RDA 100 = 10%; and (iv) RDA 120 = 25%. Specimens were then subjected to toothbrushing. Surface analyses [surface roughness Ra (SR) and scanning electron microscopy (SEM)] along with hardness and optical properties [translucency parameter (TP) and contrast ratio (CR)] were evaluated before and after toothbrushing. Statistical analyses were performed using ANOVA and Tukey test. A significant increase in SR was observed after toothbrushing with higher RDA toothpastes for Ivotion-Dent (100 and 120) and IvoBase-Hybrid (120). Ivotion-Base and Empress Direct presented no significant differences in SR when analyzed as a function of timepoint and RDA levels. Hardness was not influenced by toothbrushing with different RDA dentifrices, except for Empress Direct with RDA 0 toothpaste, where a decrease in the hardness was observed. TP of Ivotion-Dent and Empress Direct significantly decreased after toothbrushing with higher RDA dentifrices and CR of Ivotion-Dent, Empress Direct and IvoBase-Hybrid significantly increased with higher RDA dentifrices. The levels of dentifrice abrasiveness affected differently the SR, hardness and optical properties of polymeric reconstructive materials after toothbrushing. [ABSTRACT FROM AUTHOR]

To evaluate the cellular response of both an intact fish skin membrane and a porcine‐derived collagen membrane and investigate the bone healing response of these membranes using a translational, preclinical, guided‐bone regeneration (GBR) canine model. Two different naturally sourced membranes were evaluated in this study: (i) an intact fish skin membrane (Kerecis Oral®, Kerecis) and (ii) a porcine derived collagen (Mucograft®, Geistlich) membrane, positive control. For the in vitro experiments, human osteoprogenitor (hOP) cells were used to assess the cellular viability and proliferation at 24, 48, 72, and 168 h. ALPL, COL1A1, BMP2, and RUNX2 expression levels were analyzed by real‐time PCR at 7 and 14 days. The preclinical component was designed to mimic a GBR model in canines (n = 12). The first step was the extraction of premolars (P1–P4) and the 1st molars bilaterally, thereby creating four three‐wall box type defects per mandible (two per side). Each defect site was filled with bone grafting material, which was then covered with one of the two membranes (Kerecis Oral® or Mucograft®). The groups were nested within the mandibles of each subject and membranes randomly allocated among the defects to minimize potential site bias. Samples were harvested at 30‐, 60‐, and 90‐days and subjected to computerized microtomography (μCT) for three‐dimensional reconstruction to quantify bone formation and graft degradation, in addition to histological processing to qualitatively analyze bone regeneration. Neither the intact fish skin membrane nor porcine‐based collagen membrane presented cytotoxic effects. An increase in cell proliferation rate was observed for both membranes, with the Kerecis Oral® outperforming the Mucograft® at the 48‐ and 168‐hour time points. Kerecis Oral® yielded higher ALPL expression relative to Mucograft® at both 7‐ and 14‐day points. Additionally, higher COL1A1 expression was observed for the Kerecis Oral® membrane after 7 days but no differences were detected at 14 days. The membranes yielded similar BMP2 and RUNX2 expression at 7 and 14 days. Volumetric reconstructions and histologic micrographs indicated gradual bone ingrowth along with the presence of particulate bone grafts bridging the defect walls for both Kerecis Oral® and Mucograft® membranes, which allowed for the reestablishment of the mandible shape after 90 days. New bone formation significantly increased from 30 to 60 days, and from 60 to 90 days in vivo, without significant differences between membranes. The amount of bovine grafting material (%) within the defects significantly decreased from 30 to 90 days. Collagen membranes led to an upregulation of cellular proliferation and adhesion along with increased expression of genes associated with bone healing, particularly the intact fish skin membrane. Despite an increase in the bone formation rate in the defect over time, there was no significant difference between the membranes. [ABSTRACT FROM AUTHOR]

To evaluate the clinical outcomes of unsplinted implant-supported single crowns placed in adolescents, ages 10 to 19 years, and followed up from 5 to 15 years. Materials and Methods: This retrospective case series evaluated the outcomes of implant-supported single crowns placed in adolescents between June 2002 and January 2015. The patients were treated with locking-taper connection implants under a two-stage rehabilitation technique. The variables assessed included patient identification, age and reason for implant placement, implant dimensions, follow-up time, status at follow-up, and event description. To analyze peri-implant changes, bone crest level relative to the adjacent tooth was measured from periapical radiographs taken after implantation and the latest follow-up. A paired t test was performed to determine initial and follow-up differences, and data are shown as mean and 95% confidence interval. Cumulative Kaplan-Meier survival rates for implants and prostheses were calculated. Results: Twenty-one adolescent patients with ages ranging from 14 to 19 years, mainly 16 to 18 years, received a total of 37 implant-supported single crowns more frequently placed in the anterior maxilla as a result of congenital aplasia and trauma. Mean changes in bone crests were 1.99 (± 0.4) mm at the day of crown insertion and 2.23 (± 0.4) mm at the latest follow-up (average: 10 years; P = .08). No implant was lost during the follow-up period, leading to 100% implant survival. A total of 34 surviving crowns and 3 crown failures at the time of the latest follow-up led to a cumulative survival rate of 70%. The most commonly observed event was loss of proximal contacts and infraocclusion, which were handled chairside by adding resin composite. Conclusion: Unsplinted implant-supported single crowns placed in adolescents showed high implant and prosthesis survival rates, with a mean bone crest level increase of approximately 0.23 mm relative to the adjacent teeth. [ABSTRACT FROM AUTHOR]

Purpose: To establish the most effective cementation protocol for bonding zirconia crowns to Ti-Base CAD/CAM abutments in terms of abutment height, cement type, and surface pretreatment.Materials and Methods: Zirconia crowns were designed to fit abutments of 2.5-mm (short) and 4.0-mm (tall) height. The retention of conventional resin cement with a universal adhesive (RelyX Ultimate, 3M ESPE) was compared to self-adhesive resin cement (RelyX U200, 3M ESPE) following different surface pretreatments (n = 10/group): (1) no treatment (NT); (2) Ti-Base abutment surface blasting with alumina particles (SB); (3) zirconia crown tribochemical surface blasting with silica-coated alumina particles (TBS); and (4) a combination of SB + TBS. Pull-out testing was performed in a universal testing machine. Data were statistically evaluated using a linear mixed model following least significant difference post hoc test.Results: Pull-out data as a function of Ti-Base height demonstrated higher retention for tall compared to short abutments (P < .001). Ultimate outperformed U200 cement (data collapsed over height and pretreatment) (P < .001). Analysis of pretreatment depicted higher retention for SB + TBS, followed by SB, TBS, and NT (P < .04). The interaction between Ti-Base height and cement type highlighted the superior adhesive strength of Ultimate compared to U200 for both heights (P < .001). Irrespective of type of pretreatment, surface pretreatment improved the retention for U200 cement and short Ti-Base (P < .03 compared to NT). In contrast, higher retention was demonstrated for SB + TBS, followed by SB, TBS, and NT, for Ultimate cement combined with tall Ti-Base (P < .02) (data collapsed over height and cement, respectively).Conclusion: There was a direct relationship among Ti-Base height, micromechanical and/or chemical pretreatment, and conventional adhesive bonding in improving the retention of zirconia crowns. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the bone healing of tight‐fit implants placed in the maxilla and mandible of subjects compromised with metabolic syndrome (MS) and type‐2 Diabetes Mellitus (T2DM). Eighteen Göttingen minipigs were randomly distributed into three groups: (i) control (normal diet), (ii) MS (cafeteria diet for obesity induction), (iii) T2DM (cafeteria diet for obesity induction + Streptozotocin for T2DM induction). Maxillary and mandibular premolars and molar were extracted. After 8 weeks of healing, implants with progressive small buttress threads were placed, and allowed to integrate for 6 weeks after which the implant/bone blocks were retrieved for histological processing. Qualitative and quantitative histomorphometric analyses (percentage of bone‐to‐implant contact, %BIC, and bone area fraction occupancy within implant threads, %BAFO) were performed. The bone healing process around the implant occurred predominantly through interfacial remodeling with subsequent bone apposition. Data as a function of systemic condition yielded significantly higher %BIC and %BAFO values for healthy and MS relative to T2DM. Data as a function of maxilla and mandible did not yield significant differences for either %BIC and %BAFO. When considering both factors, healthy and MS subjects had %BIC and %BAFO trend towards higher values in the mandible relative to maxilla, whereas T2DM yielded higher %BIC and %BAFO in the maxilla relative to mandible. All systemic conditions presented comparable levels of %BIC and %BAFO in the maxilla; healthy and MS presented significantly higher %BIC and %BAFO relative to T2DM in the mandible. T2DM presented lower amounts of bone formation around implants relative to MS and healthy. Implants placed in the maxilla and in the mandible showed comparable amounts of bone in proximity to implants. [ABSTRACT FROM AUTHOR]

To assess the reliability and failure modes of Ti-base abutments supported by narrow and wide-diameter implant systems. Narrow (Ø3.5 × 10 mm) and wide (Ø5 × 10 mm) implant systems of two different manufacturers with internal conical connections (16°) and their respective Ti-base abutments (3.5 and 4.5 mm) were evaluated. Ti-base abutments were torqued to the implants, standardized metallic maxillary incisor crowns were cemented, and step stress accelerated life testing of eighteen assemblies per group was performed in three loading profiles: mild, moderate, and aggressive until fracture or suspension. Reliability for missions of 100,000 cycles at 100 and 150 N was calculated, and fractographic analysis was performed. For missions at 100 N for 100,000 cycles, both narrow and wide implant systems exhibited a high probability of survival (≥99%, CI: 94–100%) without significant differences. At 150 N, wide-diameter implants presented higher reliability (≥99%, CI: 99–100%) compared to narrow implants (86%, CI: 61–95%), with no significant differences among manufacturers. Failure mode predominantly involved Ti-base abutment fractures at the abutment platform. Ti-base abutments supported by narrow and wide implant systems presented high reliability for physiologic masticatory forces, whereas for high load-bearing applications, wide-diameter implants presented increased reliability. Failures were confined to abutment fractures. [ABSTRACT FROM AUTHOR]

The present study aimed to evaluate the effect of dipyridamole, an indirect adenosine 2A receptors (A2AR), on the osseointegration of titanium implants in a large, translational pre-clinical model. Sixty tapered, acid-etched titanium implants, treated with four different coatings ((i) Type I Bovine Collagen (control), (ii) 10 μM dipyridamole (DIPY), (iii) 100 μM DIPY, and (iv) 1000 μM DIPY), were inserted in the vertebral bodies of 15 female sheep (weight ~65 kg). Qualitative and quantitative analysis were performed after 3, 6, and 12 weeks in vivo to assess histological features, and percentages of bone-to-implant contact (%BIC) and bone area fraction occupancy (%BAFO). Data was analyzed using a general linear mixed model analysis with time in vivo and coating as fixed factors. Histomorphometric analysis after 3 weeks in vivo revealed higher BIC for DIPY coated implant groups (10 μM (30.42% ± 10.62), 100 μM (36.41% ± 10.62), and 1000 μM (32.46% ± 10.62)) in comparison to the control group (17.99% ± 5.82). Further, significantly higher BAFO was observed for implants augmented with 1000 μM of DIPY (43.84% ± 9.97) compared to the control group (31.89% ± 5.46). At 6 and 12 weeks, no significant differences were observed among groups. Histological analysis evidenced similar osseointegration features and an intramembranous-type healing pattern for all groups. Qualitative observation corroborated the increased presence of woven bone formation in intimate contact with the surface of the implant and within the threads at 3 weeks with increased concentrations of DIPY. Coating the implant surface with dipyridamole yielded a favorable effect with regard to BIC and BAFO at 3 weeks in vivo. These findings suggest a positive effect of DIPY on the early stages of osseointegration. [ABSTRACT FROM AUTHOR]

Objective: The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence‐based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all‐ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes. Overview: Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin‐matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth. Conclusions: Based on several clinical research, materials, and patient‐related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process. Clinical Significance: The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long‐term clinical trials in order to incorporate or not new materials and technological advancements. [ABSTRACT FROM AUTHOR]

Introduction: This study evaluated the 10‐year survival and success of partial fixed dental prostheses (P‐FDPs) fabricated with a milled fiber‐reinforced composite (FRC) framework, supported by short or extra‐short implants. Methods: Patients restored with FRC P‐FDPs supported by short or extra‐short implants were included in this retrospective study. Kaplan–Meier analysis was used to calculate the survival and success rates of the prostheses. Univariate and multivariate Cox regression models, clustered to adjust for multiple implants and prostheses being placed in the same patient, were used to correlate changes in peri‐implant bone levels with patient, implant, and prosthesis‐related covariates. Results: This study followed 121 FRC P‐FDPs supported by 261 implants, placed in 96 patients. At 118 months in function, the P‐FDP survival rate was 95.9% (95% CI: 87.5%–98.7%), and the success rate was 89.8% (95%CI: 80.4%–94.8%). Differences in prosthesis span length, abutment/pontic ratio, and the presence of distal extensions (cantilevers) did not affect the prosthetic outcomes. Bone levels around implants were stable, with an average rate of change of −0.01 ± 0.05 mm/month. Cox regression revealed that grafted sites were correlated with peri‐implant bone loss, while longer prosthetic spans were correlated with bone gain. Conclusion: P‐FDPs comprised of milled fiber‐reinforced composite frameworks, supported by short and extra‐short implants, had high survival and success rates for up to 10 years. [ABSTRACT FROM AUTHOR]

This study evaluated the probability of survival, failure mode, and stress distribution of narrow diameter implants (NDIs) with internal implant–abutment conical connection comprised of different taper angles and thread designs. Sixty‐three NDIs (Ø 3.5 × 8.5 mm) were divided according to the taper angle (TA), internal diameter (ID), and trapezoidal thread design (TD) (n = 21/group), as follows: (a) 11.5°U (11.5° TA; ID: 2.5 mm; TD: dual threaded); (b) 11.5°S (11.5° TA; ID: 2.5 mm; TD: single threaded); (c) 16°S (16° TA; ID: 2.72 mm; TD: single threaded). They were subjected to step‐stress accelerated life testing. The reliability and use‐level probability Weibull curves were calculated at 50, 100, and 150 N for a mission of 100,000 cycles and the failure mode was analyzed using a scanning electron microscope. For finite element analysis the von‐Mises stress (σvM) was calculated for the abutment and implant. All groups showed high reliability (above 84%) and failures occurred predominantly in the abutment. In the FEA, 11.5°U showed higher σvM for the implant. All NDIs showed high reliability at clinically challenging loads. The system with greater taper angle showed lower σVm in the implant, and dual threaded implants showed a higher stress concentration in the implant and cortical bone. [ABSTRACT FROM AUTHOR]

Purpose: Encouraging results have been reported for ultrashort single implants; however, long-term investigations are warranted for full-arch reconstructions. This study evaluated marginal bone loss, implant, and reconstruction survival of fiber-reinforced composite full-arch prostheses supported by 4 ultrashort implants.Methods: Patients with severely atrophic mandibles (Cawood and Howell class V and class VI) were included in this cohort study. Study predictors included time (initial and last follow-up) and vertical (epicrestally or subcrestally) and horizontal implant position (medial or lateral). Outcome variables included bone level changes over time, implant/prosthesis survival. Peri-implant bone level was measured on panoramic radiographs. Descriptive statistics, Kaplan-Meier, mixed model analysis of variance, and univariate and multivariate Cox Proportional Hazards Regression models, adjusted for multiple implants in the same patient, were used for data analyses.Results: Eighteen patients (mean 61.22 years old), with 72 implants placed in atrophic mandibles with an average follow-up of 55.4 months (CI, ±4.6/ SD, ±10.6 months) were analyzed. The implant survival rate was 97.2% as 2 implants were not loaded due to non-osseointegration and sensorial disturbances. Average marginal bone level at baseline (1.93 mm) and at the time of last recall (1.91 mm) was not significantly different. While implants placed subcrestally showed no significant difference between baseline (1.91 mm) and last follow up bone level (2.12 mm), implants placed epicrestally demonstrated a significant reduction on their bone level over time (initial: 1.97 mm/ final:1.33 mm). Systemic disorders were a risk factor for implant survival and bone loss. Prostheses cumulative survival rate was 100% (mean observation period of 55 months). The estimated survival rate after the 96-month follow-up was 75% (1 framework fracture after 84 months).Conclusion: Fixed fiber-reinforced composite full-arch prostheses retained by 4 ultrashort implants showed a stable bone level and high implant/prostheses survival rates up to 8 years. [ABSTRACT FROM AUTHOR]

To characterize the physicomechanical properties of an alumina‐toughened zirconia (ATZ). ATZ synthesis consisted of the addition of alumina particles in an yttria‐stabilized tetragonal zirconia polycrystals (3Y‐TZP) matrix. Specimens were obtained by uniaxial and isostatic pressing ATZ and 3Y‐TZP powders and sintering at 1600°C/1 h and 1550°C/1 h, respectively. Crystalline content and residual stress were evaluated using X‐ray diffraction (XRD). Microstructure was characterized by scanning electron microscopy (SEM). Optical properties were determined by reflectance test. Mechanical properties were assessed by biaxial flexural strength test. All analyses were performed before and after aging (134°C, 20 h, 2 bar). XRD and SEM revealed a typical ATZ and 3Y‐TZP crystalline content, chiefly tetragonal phase, with a dense polycrystalline matrix, though a smaller grain size for ATZ. Aging triggered a similar monoclinic transformation for both systems; however, ATZ exhibited higher residual compressive stresses than 3Y‐TZP. While as‐processed 3Y‐TZP demonstrated significantly higher characteristic strength relative to ATZ, no significant difference was observed after aging (~215 MPa increase in the ATZ strength). ATZ presented significantly higher opacity relative to 3Y‐TZP, although aging significantly increased the translucency of both systems (increase difference significantly higher in the 3Y‐TZP compared to ATZ). ATZ physicomechanical properties support its applicability in the dental field, with a lower detrimental effect of aging relative to 3Y‐TZP. [ABSTRACT FROM AUTHOR]

Background: Osseodensification (OD) has shown to improve implant stability; however, the influences of implant design, dimensions, and surgical site characteristics are unknown. Purpose To compare the insertion torque (IT) and temporal implant stability quotients (ISQ) of implants placed via OD or subtractive drilling (SD). Materials and Methods: This multicenter controlled clinical trial enrolled 56 patients, whom were in need of at least 2 implants (n = 150 implants). Patients were treated with narrow, regular, or wide implants and short, regular, or long implants in the anterior or posterior region of the maxilla or in the posterior region of the mandible. Osteotomies were performed following manufacturers recommendation. IT was recorded with a torque indicator. ISQ was recorded with resonance frequency analysis immediately after surgery, 3 and 6 weeks. Results: Data complied as a function of osteotomy indicated significantly higher IT for OD relative to SD. OD outperformed conventional SD for all pairwise comparisons of arches (maxilla and mandible) and areas operated (anterior and posterior), diameters and lengths of the implants, except for short implants. Overall, ISQ data also demonstrated significantly higher values for OD compared to SD regardless of the healing period. Relative to immediate readings, ISQ values significantly decreased at 3 weeks, returning to immediate levels at 6 weeks; however, ISQ values strictly remained above 68 throughout healing time for OD. Data as a function of arch operated and osteotomy, area operated and osteotomy, implant dimensions and osteotomy, also exhibited higher ISQ values for OD relative to SD on pairwise comparisons, except for short implants. Conclusions: OD demonstrated higher IT and temporal ISQ values relative to SD, irrespective of arch and area operated as well as implant design and dimension, with an exception for short implants. Future studies should focus on biomechanical parameters and bone level change evaluation after loading. [ABSTRACT FROM AUTHOR]

Objective: To investigate the probability of survival and failure modes of four‐unit implant‐supported porcelain fused to metal (PFM) dentogingival prostheses subjected to step‐stress accelerated life testing (SSALT). Materials and methods: Eighteen implant‐supported PFM dentogingival prostheses with thin metallic infrastructures, which provided minimal ceramic support and improved esthetics were fabricated over external hexagonal connection UCLA abutments. SSALT was performed until specimen failure. Use level probability Weibull curve and reliability were calculated and plotted. Weibull modulus (m) and characteristic strength (η) were also calculated. Polarized light microscope and scanning electron microscope were used to characterize fractures. Results: Failures were dictated by material strength rather than fatigue damage accumulation. The probability of survival for loads reaching 100 and 150 N in 100,000 cycles was 92 and 61%, respectively. No cracks or fractures were identified in the veneered porcelain, whereas abutment fixation screw fracture was the chief failure mode. Conclusion: Implant‐supported PFM four‐unit dentogingival prostheses with minimum metal framework dimensions presented favorable lifetime prediction under fatigue testing. Fractures were restricted to fixation screws. Clinical significance: In‐vitro fatigue testing and failure mode analyses evidenced favorable lifetime prediction for 4‐unit implant‐supported dentogingival prostheses with minimum metal frameworks. Abutment fixation screw fracture might be the most frequent clinical complication. Since this proof of concept has been tested in‐vitro, further studies including different restorative materials, as well as long‐term clinical trials are warranted. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of resin cement type, surface pretreatment and autoclave sterilization on the retention of Y-TZP crowns to Ti-base abutments. Methods: Y-TZP crowns were designed and milled to fit Ti-base abutments. Crowns were cemented using either a conventional resin cement (conventional) with a universal adhesive or a self-adhesive resin cement (self-adhesive), both following no surface pretreatment (No) or Ti-base abutment sandblasting (SB) (n=20/group). Half of the cemented samples were subjected to in-office autoclave sterilization. Pullout testing was performed in a universal testing machine at a speed of 1 mm/min until crown displacement. Data were statistically evaluated through a linear mixed model following post hoc comparisons by LSD test. Results: Pullout data as a function of cement type demonstrated higher retention for conventional relative to self-adhesive cement (p<0.001). Ti-base sandblasting (SB) favored crown retentiveness over No pretreatment (p<0.001). Sterilized crowns exhibited higher pullout values than non-sterile (p=0.036). All the two- and three-factor interaction analyses corroborated with the superior adhesive strength of conventional compared to self-adhesive cement (all, p<0.011), as well as, SB relative to No pretreatment (all, p<0.024). While autoclave sterilization maximized bond strength when self-adhesive cement (data collapsed over surface pretreatment, p<0.050) and No pretreatment were evaluated (data collapsed over surface pretreatment, p<0.013), no significant difference was observed for conventional resin cement (p=0.280) and SB (p=0.878) groups. Conclusions: Conventional resin cement and/or Ti-base sandblasting increased Y-TZP crown retentiveness, with no significant influence of autoclave sterilization. Autoclaving increased retentiveness when self-adhesive cement and/or no Ti-base pretreatment were used. [ABSTRACT FROM AUTHOR]

Aim: To compare the marginal fit of lithium disilicate CAD/CAM crowns and heat-pressed crowns fabricated using milled wax patterns, and evaluate its effect on stress distribution in implantsupported rehabilitation. Methods: A CAD model of a mandibular first molar was designed, and 16 lithium disilicate crowns (8/group) were obtained. The crown-prosthetic abutment set was evaluated in a scanning electron microscopy. The mean misfit for each group was recorded and evaluated using Student's t-test. For in silico analysis, a virtual cement thickness was designed for the two misfit values found previously, and the CAD model was assembled on an implant-abutment set. A load of 100 N was applied at 30° on the central fossa, and the equivalent stress was calculated for the crown, titanium components, bone, and resin cement layer. Results: The CAD/CAM group presented a significantly (p=0.0068) higher misfit (64.99±18.73 μm) than the heat-pressed group (37.64±15.66 μm). In silico results showed that the heat-pressed group presented a decrease in stress concentration of 61% in the crown and 21% in the cement. In addition, a decrease of 14.5% and an increase of 7.8% in the stress for the prosthetic abutment and implant, respectively, was recorded. For the cortical and cancellous bone, a slight increase in stress occurred with an increase in the cement layer thickness of 5.9% and 5.7%, respectively. Conclusion: The milling of wax patterns for subsequent inclusion and obtaining heat-pressed crowns is an option to obtain restorations with an excellent marginal fit and better stress distribution throughout the implant-abutment set. [ABSTRACT FROM AUTHOR]

The reduced hardware design of narrow implants increases the risk of fracture not only of the implant itself but also of the prosthetic constituents. Hence, the current study is aimed at estimating the probability of survival of anterior crowns supported by different narrow implant systems. Three different narrow implant systems of internal conical connections were evaluated (Ø 3.5 × 10 mm): (i) Active (Nobel Biocare), (ii) Epikut (S.I.N. Implant System), and (iii) BLX (Straumann). Abutments were torqued to the implants, and standardized maxillary incisor crowns were cemented. The assemblies were subjected to step-stress accelerated life testing (SSALT) in water through load application of 30 degrees off-axis lingually at the incisal edge of the crowns using a flat tungsten carbide indenter until fracture or suspension. The use level probability Weibull curves and reliability for completion of a mission of 100,000 cycles at 80 N and 120 N were calculated and plotted. Weibull modulus and characteristic strength were also calculated and plotted. Fractured samples were analyzed in a stereomicroscope. The beta (β) values were 1.6 (0.9-3.1) and 1.4 (0.9-2.2) for BLX and Active implants, respectively, and 0.5 (0.3-0.8) for the Epikut implant, indicating that failures were mainly associated with fatigue damage accumulation in the formers, but more likely associated with material strength in the latter. All narrow implant systems showed high probability of survival (≥95%, CI: 85-100%) at 80 and 120 N, without significant difference between them. Weibull modulus ranged from 6 to 14. The characteristic strength of Active, Epikut, and BLX was 271 (260-282) N, 216 (205-228) N, and 275 (264-285) N, respectively. The failure mode predominantly involved abutment and/or abutment screw fracture, whereas no narrow implant was fractured. Therefore, all narrow implant systems exhibited a high probability of survival for anterior physiologic masticatory forces, and failures were restricted to abutment and abutment screw. [ABSTRACT FROM AUTHOR]

Implant therapy is a predictable treatment to replace missing teeth. However, the osseointegration process may be negatively influenced by systemic conditions, such as diabetes mellitus (DM). Microtopography and implant surface developments are strategies associated to better bone repair. This study aimed to evaluate, in healthy and diabetic rats, histomorphometric (bone to implant contact = %BIC; and bone area fraction occupancy = %BAFO) and nanomechanical (elastic modulus = EM; and hardness = H) bone parameters, in response to a nanometric hydroxyapatite implant surface. Mini implants (machined = MAC; double acid etched = DAE, and with addition of nano-hydroxyapatite = NANO) were installed in tibias of healthy and diabetic rats. The animals were euthanized at 7 and 30 days. NANO surface presented higher %BIC and %BAFO when compared to MAC and DAE (data evaluated as a function of implant surface). NANO surface presented higher %BIC and %BAFO, with statistically significant differences (data as a function of time and implant surface). NANO surface depicted higher EM and H values, when compared to machined and DAE surfaces (data as a function of time and implant surface). Nano-hydroxyapatite coated implants presented promising biomechanical results and could be an important tool to compensate impaired bone healing reported in diabetics. [ABSTRACT FROM AUTHOR]

Purpose: This study aimed to evaluate the 10-year outcomes of partial fixed dental prostheses (P-FDPs) fabricated using metal-free fiber-reinforced composite (FRC) resin frameworks veneered with composite resin and supported by short and extra-short implants., Methods: This study included 28 patients with 38 FRC prostheses supported by 96 implants. Implant and prosthesis survival and success rates were evaluated using Kaplan-Meier analysis., Results: The 10-year implant survival and success rate, as determined by Kaplan-Meier analysis, was 96.9%, and the prosthesis survival and success rates were 94.7% and 92.0%, respectively. None of the parameters under investigation were significantly correlated with prosthetic survival or successful outcomes, but three parameters were correlated with higher peri-implant bone levels: implant placement in the mandible as opposed to the maxilla, shorter P-FDP spans, and natural teeth on the opposing arch., Conclusions: FRC P-FDPs supported by short and extra-short implants presented high, up to 10-year, survival and success rates, when used to restore partially edentulous arches.

Background: Polylactic acid (PLA) has been extensively used in tissue engineering. However, poor mechanical properties and low cell affinity have limited its pertinence in load bearing bone tissue regeneration (BTR) devices., Objective: Augmenting PLA with β-Tricalcium Phosphate (β-TCP), a calcium phosphate-based ceramic, could potentially improve its mechanical properties and enhance its osteogenic potential., Methods: Gels of PLA and β-TCP were prepared of different % w/w ratios through polymer dissolution in acetone, after which polymer-ceramic membranes were synthesized using the gel casting workflow and subjected to characterization., Results: Gel-cast polymer-ceramic constructs were associated with significantly higher osteogenic capacity and calcium deposition in differentiated osteoblasts compared to pure polymer counterparts. Immunocytochemistry revealed cell spreading over the gel-cast membrane surfaces, characterized by trapezoidal morphology, distinct rounded nuclei, and well-aligned actin filaments. However, groups with higher ceramic loading expressed significantly higher levels of osteogenic markers relative to pure PLA membranes. Rule of mixtures and finite element models indicated an increase in theoretical mechanical strength with an increase in β-TCP concentration., Conclusion: This study potentiates the use of PLA/β-TCP composites in load bearing BTR applications and the ability to be used as customized patient-specific shape memory membranes in guided bone regeneration.

Objectives: To assess the effects of different aging protocols on chemical, physical, and mechanical properties of an experimental ATZ composite compared to a zirconia., Methods: Disc-shaped specimens were obtained through uniaxial pressing of commercial powders (Tosoh), ATZ comprised of 80%ZrO 2 /20%Al 2 O 3 (TZ-3YS20AB) and 3Y-TZP (3Y-SBE). The specimens of each material were divided into different groups according to the aging protocol: immediate, autoclave aging and hydrothermal reactor aging. The aging protocols were performed at 134 ºC for 20 h at 2.2 bar. Crystalline evaluations were performed using X-Ray Diffraction. The nanoindentation tests measured the elastic modulus (Em) and hardness (H). Biaxial flexural strength was performed, and Weibull statistics were used to determine the characteristic strength and Weibull modulus. The probability of survival was also determined. The Em and H data were analyzed by one-way ANOVA and Tukey test., Results: Diffractograms revealed the presence of monoclinic phase in both materials after aging. The hydrothermal reactor decreased the Em for ATZ compared to its immediate condition; and the H for both ATZ and 3Y-TZP regarding their immediate and autoclave aging conditions, respectively. The aging protocols significantly increased the characteristic strength for ATZ, while decreased for 3Y-TZP. No difference regarding Weibull modulus was observed, except for 3Y-TZP aged in reactor. For missions of up to 500 MPa, both materials presented a high probability of survival (>99 %) irrespective of aging condition., Significance: The synthesized ATZ composite exhibited greater physical and microstructural stability compared to 3Y-TZP, supporting potential application of the experimental material for long-span reconstructive applications., (Copyright © 2024 Elsevier Inc. All rights reserved.)

The present work aims to develop a production method of pre-sintered zirconia-toughened-alumina (ZTA) composite blocks for machining in a computer-aided design and computer-aided manufacturing (CAD-CAM) system. The ZTA composite comprised of 80% Al 2 O 3 and 20% ZrO 2 was synthesized, uniaxially and isostatically pressed to generate machinable CAD-CAM blocks. Fourteen green-body blocks were prepared and pre-sintered at 1000 °C. After cooling and holder gluing, a stereolithography (STL) file was designed and uploaded to manufacture disk-shaped specimens projected to comply with ISO 6872:2015. Seventy specimens were produced through machining of the blocks, samples were sintered at 1600 °C and two-sided polished. Half of the samples were subjected to accelerated autoclave hydrothermal aging (20h at 134 °C and 2.2 bar). Immediate and aged samples were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). Optical and mechanical properties were assessed by reflectance tests and by biaxial flexural strength test, Vickers indentation and fracture toughness, respectively. Samples produced by machining presented high density and smooth surfaces at SEM evaluation with few microstructural defects. XRD evaluation depicted characteristic peaks of alpha alumina and tetragonal zirconia and autoclave aging had no effect on the crystalline spectra of the composite. Optical and mechanical evaluations demonstrated a high masking ability for the composite and a characteristic strength of 464 MPa and Weibull modulus of 17, with no significant alterations after aging. The milled composite exhibited a hardness of 17.61 GPa and fracture toughness of 5.63 MPa m 1/2 , which remained unaltered after aging. The synthesis of ZTA blocks for CAD-CAM was successful and allowed for the milling of disk-shaped specimens using the grinding method of the CAD-CAM system. ZTA composite properties were unaffected by hydrothermal autoclave aging and present a promising alternative for the manufacture of infrastructures of fixed dental prostheses., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

To develop a peri-implantitis model in a Gottingen minipig and evaluate the effect of local application of salicylic acid poly(anhydride-ester) (SAPAE) on peri-implantitis progression in healthy, metabolic syndrome (MS), and type-2 diabetes mellitus (T2DM) subjects. Eighteen animals were allocated to three groups: (i) control, (ii) MS (diet for obesity induction), and (iii) T2DM (diet plus streptozotocin for T2DM induction). Maxillary and mandible premolars and first molar were extracted. After 3 months of healing, four implants per side were placed in both jaws of each animal. After 2 months, peri-implantitis was induced by plaque formation using silk ligatures. SAPAE polymer was mixed with mineral oil (3.75 mg/μL) and topically applied biweekly for up to 60 days to halt peri-implantitis progression. Periodontal probing was used to assess pocket depth over time, followed by histomorphologic analysis of harvested samples. The adopted protocol resulted in the onset of peri-implantitis, with healthy minipigs taking twice as long to reach the same level of probing depth relative to MS and T2DM subjects (∼3.0 mm), irrespective of jaw. In a qualitative analysis, SAPAE therapy revealed decreased levels of inflammation in the normoglycemic, MS, and T2DM groups. SAPAE application around implants significantly reduced the progression of peri-implantitis after ∼15 days of therapy, with ∼30% lower probing depth for all systemic conditions and similar rates of probing depth increase per week between the control and SAPAE groups. MS and T2DM conditions presented a faster progression of the peri-implant pocket depth. SAPAE treatment reduced peri-implantitis progression in healthy, MS, and T2DM groups.

This study aimed to develop a recycling process for the remnants of milled 3Y-TZP and enhance their properties using glass infiltration. 3Y-TZP powder was gathered from the vacuum system of CAD-CAM milling equipment, calcined and sieved (x < 75 μm). One hundred twenty discs were fabricated and pre-sintered at 1000 °C/h. These specimens were then divided into four groups, categorized by glass infiltration (non-infiltrated [Zr] or glass-infiltrated [Zr-G]) and sintering temperature (1450 °C [Zr-1450] or 1550 °C [Zr-1550]/2h). After sintering, the specimens were characterized by X-Ray Diffraction (XRD), relative density measurement, and scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS). The biaxial flexural strength test was performed according to the ISO 6872 and followed by fractographic analysis. Subsequent results were analyzed using Weibull statistics. Relative density values of the sintered specimens from Zr-1450 and Zr-1550 groups were 86.7 ± 1.5% and 92.2 ± 1.7%, respectively. Particle size distribution revealed particles within the range of 0.1-100 μm. XRD analysis highlighted the presence of the ZrO 2 -tetragonal in both the Zr-1450 and Zr-1550 groups. Glass infiltration, however, led to the formation of the ZrO 2 -monoclinic of 9.84% (Zr-1450-G) and 18.34% (Zr-1550-G). SEM micrographs demonstrated similar microstructural characteristics for Zr-1450 and Zr-1550, whereas the glass-infiltrated groups exhibited comparable infiltration patterns. The highest characteristic strength was observed in the glass-infiltrated groups. Fractographic analyses suggested that fracture origins were related to defects on the tensile side, which propagated to the compression side of the samples. Both the sintering temperature and glass infiltration significantly influenced the mechanical properties of the 3Y-TZP recycled., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Objectives: To process an alumina-toughened zirconia (ATZ) nanocomposite and to characterize its crystalline phases, microstructure, residual stress, mechanical and optical properties before and after two different artificial aging methodologies., Methods: Disc-shaped specimens were obtained through uniaxial pressing of a commercial ATZ powder comprised of 80%ZrO 2 / 20%Al 2 O 3 , with a particle size of 50 nm and 150 nm, respectively. Sintering was performed at 1500ºC for 2 h. Groups were established according to the aging protocol as immediate (ATZ-I) and aged either in autoclave (ATZ-A) or hydrothermal reactor (ATZ-R) at 134 ºC for 20 h at 2.2 bar. Crystalline phases and microstructure were assessed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. Residual stress was evaluated by Raman spectroscopy. Contrast Ratio (CR) and Translucency Parameter (TP) were calculated to characterize optical properties. Mechanical properties were analyzed through Vickers microhardness, fracture toughness, and biaxial flexural strength test., Results: XRD spectra of both aging protocols revealed the presence of monoclinic zirconia (20-31%), where higher phase transformation was observed after aging in hydrothermal reactor. Optical properties evaluation demonstrated high opacity (CR: 0.99) and masking ability (TP: 0.26), with no significant differences after aging. Raman spectroscopy evidenced the presence of residual compressive stresses in the aged groups, being significantly higher for ATZ-R (-215.2 MPa). As-sintered specimens revealed hardness of ∼12.3 GPa and fracture toughness of ∼1.9 MPa.m 1/2 . Characteristic strength was 740 MPa for ATZ-I, 804 MPa for ATZ-A, and 879 MPa for ATZ-R, with significant differences between groups. Weibull modulus ranged from 16.5 to 18.8. All groups demonstrated high reliability up to 500 MPa stress missions (99-100%), with no significant differences after aging., Significance: The experimental ATZ nanocomposite presented high opacity and a high Weibull modulus. While aging created internal compressive stress responsible for an increase in characteristic strength, the nanocomposite was susceptible to hydrothermal degradation. Further studies are required to evaluate its degradation kinetics at low temperatures., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Statement of Problem: The bonding of implant-supported prostheses is determined by abutment material, convergence angle, height, surface treatment, and luting agents. However, studies evaluating the bonding of luting agents to titanium base abutments with different heights under fatigue conditions are scarce., Purpose: The purpose of this in vitro study was to evaluate the retention of zirconia crowns bonded with different luting agents to titanium base abutments of different heights before and after fatigue testing., Material and Methods: Zirconia crowns were designed, milled, and distributed into 4 experimental groups according to the luting agents (G-Multi Primer/G-Cem LinkForce [MP/GC] and Scotchbond Universal/RelyX Ultimate [SU/RU]) and titanium base abutment heights (2.5 mm and 4 mm) (n=10). Pull-out testing was performed in a universal testing machine at a crosshead speed of 1 mm/min until crown displacement. Fatigue testing was performed by an electric precision fatigue simulator (1×10 6 cycles; 100 N; and 15 Hz), followed by pull-out testing of fatigued specimens. Collected data were statistically evaluated by using a linear mixed model after post hoc comparisons by the least significant difference test (α=.05)., Results: Luting agents, abutment heights, and fatigue influenced the bonding retention of zirconia crowns to titanium base abutments. SU/RU agents promoted higher pull-out compared with MP/GC for both abutment heights before and after fatigue. Higher abutment height increased pull-out regarding lower abutment height for SU/RU materials before and after fatigue testing. Although fatigue had no significant effect on the pull-out of MP/GC, lower bond retention was observed for SU/RU after fatigue, regardless of abutment height., Conclusions: Luting agent composition and the interaction with abutment height and fatigue influenced the retention of zirconia crowns to titanium base abutments., (Copyright © 2023 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Defects characterized as large osseous voids in bone, in certain circumstances, are difficult to treat, requiring extensive treatments which lead to an increased financial burden, pain, and prolonged hospital stays. Grafts exist to aid in bone tissue regeneration (BTR), among which ceramic-based grafts have become increasingly popular due to their biocompatibility and resorbability. BTR using bioceramic materials such as β-tricalcium phosphate has seen tremendous progress and has been extensively used in the fabrication of biomimetic scaffolds through the three-dimensional printing (3DP) workflow. 3DP has hence revolutionized BTR by offering unparalleled potential for the creation of complex, patient, and anatomic location-specific structures. More importantly, it has enabled the production of biomimetic scaffolds with porous structures that mimic the natural extracellular matrix while allowing for cell growth-a critical factor in determining the overall success of the BTR modality. While the concept of 3DP bioceramic bone tissue scaffolds for human applications is nascent, numerous studies have highlighted its potential in restoring both form and function of critically sized defects in a wide variety of translational models. In this review, we summarize these recent advancements and present a review of the engineering principles and methodologies that are vital for using 3DP technology for craniomaxillofacial reconstructive applications. Moreover, we highlight future advances in the field of dynamic 3D printed constructs via shape-memory effect, and comment on pharmacological manipulation and bioactive molecules required to treat a wider range of boney defects.

This systematic review addressed the implant success rate after mandible reconstruction with vascularized fibula bone graft. Therefore, preferred reporting items for systematic review and meta-analysis guidelines were used to perform the systematic review, and the search included following databases: PubMed, Lilacs, Google Scholar, Open Gray, Science Direct and Cochrane. A search of medical subject headings (MeSH) and related terms (fibula) OR (vascularized) OR (microvascularized) AND (implant) OR (rehabilitation) OR (osseointegrated) AND (mandible) OR (jaw) OR (maxillofacial), without any language or time restrictions until October 2017 was carried out. The eligible studies primarily consisted of clinical cohorts designed to evaluate the feasibility of mandible reconstruction using vascularized fibula bone grafts and implant-supported rehabilitations, with a minimum observation period of 12 months. After screening, 13 eligible cohort studies for this review were selected (3 retrospective and 10 prospective). Of 285 vascularized fibular reconstructions, only 6 failures were reported with a success rate of approximately 98% after a mean follow-up period of 40 months. In total, 910 implants were placed in vascularized fibular grafts with a success rate of 92.6% (range, 82%-100%) after 40 months. Also, similar success rates for primary (95%; range, 93%-100%) and secondary (91%; range, 83%-100%) implant surgeries have been demonstrated. Considering risk factors, implant survival in irradiated patients was usually lower (76%; range, 38%-88%) than nonirradiated patients (90%; range, 83%-94%); however, it was significantly different in only 1 study. Alcohol and tobacco use has shown no significant association with implant failure in any study. Hence, implant placement in vascularized fibula bone graft presented similar success rates relative to native mandible bone rehabilitations.

Purpose: This study evaluated the probability of survival and failure mode of endodontically treated incisors without ferrule restored with CAD/CAM FRC post-cores., Methods: Root canals of bovine incisors were treated, leaving post preparations of ∼10 mm. Teeth were allocated into three groups: (i) cast metal post-core, (ii) FRC prefabricated post with a direct resin core build-up, and (iii) CAD/CAM FRC post-core. Posts and zirconia crowns were cemented using resin cement. Specimens were subjected to step-stress accelerated-life fatigue testing in water. Use level probability Weibull curves, probability of survival for a mission of 100,000 cycles at 25, 50, and 100 N, Weibull modulus, and characteristic strength were calculated and plotted. Failure mode was examined under a stereomicroscope., Results: Restored incisors demonstrated high probability of survival (93-100%) for missions estimated at 25 and 50 N, irrespective of post-core foundation. At 100 N, incisors restored with metal posts presented significantly higher probability of survival (99%) relative to CAD/CAM posts (79%), whereas FRC groups demonstrated no significant difference. Weibull analysis indicated no significant difference on the Weibull modulus (m = 3.38-5.92). Incisors reconstructed with metal post-cores (431 N) presented significantly higher characteristic strength relative to prefabricated (200 N) and CAD/CAM (202 N) FRC post-cores. While post fracture was the chief failure mode for prefabricated and CAD/CAM FRC post-cores, post and/or root fracture were the main event for metal post-cores., Conclusion: Endodontically treated incisors without ferrule restored with CAD/CAM FRC post-cores presented promising probability of survival for loads compatible with anterior masticatory forces and favorable failure modes., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022. Published by Elsevier Ltd.)

To evaluate the effect of fatigue and aging on the crystalline content and reliability of a zirconia-toughened-alumina (ZTA) composite compared to its individual counterpart materials (3Y-TZP and Al 2 O 3 ). Thirty-six disc-shaped specimens per group were obtained to comply with ISO 6872:2015. Crystalline content, microstructure and reliability of experimental groups were evaluated in four stages: 1) immediate; 2) aged; 3) fatigued; 4) aged + fatigue. Aging was performed in autoclave and Step-Stress-Accelerated-Life-Testing (SSALT) was performed using three stress profiles. Weibull statistics were used to determine Weibull parameters and life-expectancy. A significant increase in monoclinic phase in 3Y-TZP was observed after aging (19.31%), fatigue (17.88%) and aging + fatigue (55.81%), while ZTA evidenced minimal variation among all conditions (<5.69%). 3Y-TZP presented higher reliability than ZTA at 300 and 500 MPa, and ZTA outperformed Al 2 O 3 at the same stress missions. None of the ceramics yielded acceptable reliability at 800 MPa. A higher characteristic strength was observed for 3Y-TZP, followed by ZTA and Al 2 O 3 . While after aging ZTA and Al 2 O 3 remained stable, 3Y-TZP exhibited a significant increase in the characteristic stress. Aging did not affect the reliability of ZTA and Al 2 O 3 . 3Y-TZP demonstrated an increase in monoclinic content and characteristic strength after aging., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Purpose: To evaluate the effect of composition, fabrication mode, and thermal cycling on the mechanical properties of different polymeric systems used for temporary dental prostheses., Materials and Methods: Standard bar-shaped specimens (25 × 2 × 2 mm) were fabricated of six polymeric systems of varying compositions and fabrication modes (n = 10/group): conventional PMMA (Alike, GC) - group CGC; conventional PMMA (Dêncor, Clássico) - group CD; bis-acryl (Tempsmart, GC) - group BGC; bis-acryl (Yprov, Yller) - group BY; milled PMMA (TelioCAD, Ivoclar) - group MI; 3D printed bis-acryl - (Cosmos Temp, Yller) group PY. Half of the specimens were subjected to 5000 thermal cycles (5 °C to 55 °C). Three-point bending tests were performed using a universal testing machine with a crosshead speed set to 0.5 mm/min. Flexural strength and elastic modulus were calculated from the collected data. FTIR spectra were recorded pre and post curing and after thermal cycling to evaluate material composition and degree of conversion. Energy-dispersive spectroscopy (EDS) and scanning electron microscope (SEM) were utilized to examine the composition and micromorphology of the systems, respectively. Data were analyzed using two-analysis of variance and Tukey tests (α = 0.05)., Results: FTIR spectra indicated that BGC, BY and PY groups corresponded to urethane dimethacrylate systems (bis-acryl), while CGC, CD, and MI groups corresponded to monomethacrylate systems, polymethyl methacrylate (PMMA). Bis-acryl BGC system yeilded the highest flexural strength (80 MPa), followed by the milled PMMA MI system (71 MPa), both statistically significant different relative to other groups. Bis-acryl BY exhibited the lowest flexural strength (27 MPa). Thermocycling significantly increased the flexural strength of all polymeric systems (∼10-15 MPa), except for the 3D-printed PY group. Bis-acryl BGC (1.89 GPa) and conventional PMMA CGC (1.66 GPa) groups exhibited the highest elastic modulus, followed by milled PMMA MI group (1.51 GPa) and conventional PMMA CD (1.45 GPa) systems, with significant difference detected between BGC group and MI and CD groups. The 3D printed PY (0.78 GPa) and bis-acryl BY (0.47 GPa) systems presented the lowest elastic modulus. Thermocycling did not have a significant influence on the elastic modulus. FTIR spectra indicate water sorption and release of unreacted monomers as well as increased degree of conversion (∼5-12%) after thermal cycling., Conclusion: Composition and fabrication mode and thermal cycling significantly affected the mechanical properties of polymeric systems used for temporary dental prostheses., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

Abstract: The aim of this case series was to evaluate the long-term success rate of immediate occlusal loading of extrasinus zygomatic dental implants after a 3-year follow-up. The sample consisted of 31 patients (mean age of 64 years) with atrophic maxillae rehabilitated with 1 to 4 extrasinus zygomatic implants, placed unilaterally or bilaterally. All the patients received complete implant-supported dental prostheses with immediate loading by associating zygomatic implants with conventional implants. None of the procedures were associated with bone grafts. During the 3-year period of follow-up in the present study, all the patients attended clinical sessions and underwent radiographic exams every 6 months. In total 55 zygomatic and 69 conventional implants were placed, where 1 zygomatic and 2 conventional implants were lost, representing success rates of 98.18% and 97.20%, respectively. None of the studied patients had signs of sinusitis or changes in the maxillary sinuses. All the patients showed occlusal contact on natural antagonist teeth or implant-supported dental prostheses. Therefore, it was concluded that the use of exteriorized zygomatic implants with immediate loading represented a feasible option with high success rates for the treatment of atrophic maxilla., Competing Interests: The authors report no conflicts of interest., (Copyright © 2021 by Mutaz B. Habal, MD.)