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AIMS: To estimate the prevalence of self-reported symptoms associated with temporomandibular disorders (TMD) and treatment-seeking in adult Chinese in Hong Kong. METHODS: A telephone survey technique was used to identify 1,526 randomly selected Cantonese-speaking individuals aged 18 years or over. Standard questions were asked about joint and jaw muscle pain, jaw opening, and joint sounds. In addition, questions on tooth grinding and clenching, sleep patterns, and treatment-seeking behavior were posed. RESULTS: Jaw pain was reported by 33% of the population. Only 5% of them had frequent pain, with two thirds of this subgroup having moderate to severe symptoms. The prevalence of frequent problems with jaw opening and joint clicking was 0.3% and 1.8%, respectively. There were no gender-related differences in the reporting of TMD symptoms or related conditions. CONCLUSION: One percent of the Hong Kong Chinese population had TMD-related jaw pain that was of moderate or severe intensity and occurred frequently; 0.6% of the population had sought treatment for jaw pain, impaired jaw opening, or joint clicking that occurred often in the previous year. [ABSTRACT FROM AUTHOR]

Objectives: To proof the feasibility of direct colour printing on 3Y-TZP using 222 nm UV-C through investigating the degree and durability of the colour changes, and testifying whether surface, mechanical and biological properties are influenced by the treatment., Methods: 222 nm UV-C light (Irradiance: 1.870 mW/cm 2 ) was used to treat 3Y-TZP for durations from 15 min to 24 h. ΔE*, TP, crystalline structure, surface morphology, S a , BFS and biological activities were investigated before and after irradiation. SPSS 28.0 was used for statistical analysis (α = 0.05)., Results: 222 nm UV-C irradiation was capable to shade white 3Y-TZP into tooth colours. With the increase of ΔE*, TP decreased, such that the longer the irradiation time, the higher the ΔE* (logarithmic relationship) and lower the TP. Despite the induced optical changes being prone to fade, the process can be predicted by inversely proportional relationships between ΔE*, TP and the testing points. The treated surface exhibited enhanced hydrophilicity, while the recovery phenomenon was observed. Other properties were not altered by the treatment., Significance: This is the seminal study demonstrating the feasibility of direct colour printing on 3Y-TZP using 222 nm UV-C. The new relationship between the colour centre and E g of 3Y-TZP was established, whereas the induced optical changes were stabilised after a certain period and were highly predictable by controlling the irradiation periods. The irradiation was only correlated to the electron excitation and oxygen vacancies, and would not lead to any changes of other properties. A simple, safe and promising approach to achieve satisfactory colours on 3Y-TZP in clinical practice can be developed., Competing Interests: Declaration of Competing Interest There are no known conflicts of interest associated with this publication and there has been no significant financial support for this work that could have influenced its outcome., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Objectives: To investigate and compare the chemical and optical stability of four restorative composite materials: two injectable resins, one flowable resin and one compomer., Methods: Two injectable nano-filled composite resins: G-aenial Universal (GU) and Beautifil Injectable XSL (BI), a flowable composite resin: Filtek Supreme Flowable (FS) and a compomer: Dyract Flow (DF), in A2 shade were tested and compared. Water sorption and solubility were conducted according to ISO4049:2019 standard; ICP-OES and F-ion selective electrode were used to test the elemental release; Degree of conversion (DC) was obtained by using FTIR; water contact angle was obtained by static sessile drop method, and a spectrophotometer was used for optical properties (ΔE ⁎ , ΔL ⁎ and TP). SPSS 28.0 was used for statistical analysis and the significant level was pre-set as α = 0.05., Results: GU performed the best in water sorption and solubility, FS had the lowest elemental release, the best colour stability, and the highest DC IM and DC 24-h . DF, the compomer had the lowest, and GU and BI, the injectable composites had the largest water contact angle, respectively. Correlations were found between water sorption and water solubility., Conclusions: The four composite restorative materials showed different chemical and optical behaviours. Overall, composite resins performed better than compomer, while additional laboratory and in vivo tests are necessary to obtain a more comprehensive comparison between injectable and flowable composite resins. W sp and W sl are influenced by many common factors, and the values are highly positively related., Clinical Significance: A comprehensive understanding of materials is crucial before selecting materials for clinical practice. Composite resins rather than compomers are recommended because of their exceptional properties, which make them eligible for a wide range of clinical applications and an elongated lifespan., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This study is partially funded, and the materials were provided, by GC Corporation., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Objectives: To evaluate the mechanical, wear, antibacterial properties, and biocompatibility of injectable composite materials., Methods: Two injectable composite resins (GU and BI), one flowable composite resin (FS), and one flowable compomer (DF), in A2 shade, were tested. Mechanical properties were tested via three-point bending test immediately after preparation and after 1-day, 7-day, 14-day, and 30-day water storage. Under water-PMMA slurry immersion, specimens were subjected to a 3-body wear test (10,000 cycles) against stainless steel balls, while the roughness, wear depth, and volume loss were recorded. After 1-day and 3-day MC3T3-E1 cell culture, cell viability was evaluated with CCK-8 test kits, while the cell morphology was observed under CLSM and SEM. Antibacterial properties on S. mutans were assessed via CFU counting, CLSM, and SEM observation. SPSS 26.0 was used for statistical analysis (α = 0.05)., Results: The mechanical properties were material-dependent and sensitive to water storage. Flexural strength ranked GU > FS > BI > DF at all testing levels. Three nanocomposites had better wear properties than DF. No significant difference on 1-day cell viability was found, but DF showed significantly lower cell proliferation than nanocomposites on 3-day assessment. GU and FS had more favourable cell adhesion and morphology. CFU counting revealed no significant difference, while FS presented a slightly thicker biofilm and BI showed relatively lower bacteria density., Conclusions: Injectable nanocomposites outperformed the compomer regarding mechanical properties, wear resistance, and biocompatibility. The tested materials presented comparable antibacterial behaviours. Flowable resin-based composites' performances are affected by multiple factors, and their compositions can be attributed., Clinical Significance: A profound understanding of the mechanical, wear, and biological properties of the restorative material is imperative for the clinical success of dental restorations. The current study demonstrated superior properties of highly filled injectable composite resins, which imply their wider indications and better long-term clinical performances., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: This study is partially funded, with the materials supported, by GC Corporation., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Statement of Problem: Computer-aided design and computer-aided manufacturing (CAD-CAM) technology has greatly improved the efficiency of the fabrication of dental prostheses. However, the design process (CAD stage) is still time-consuming and labor intensive., Purpose: The purpose of this feasibility study was to investigate the accuracy of a novel artificial intelligence (AI) system in designing biomimetic single-molar dental prostheses by comparing and matching them to the natural molar teeth., Material and Methods: A total of 169 maxillary casts were obtained from healthy dentate participants. The casts were digitized, duplicated, and processed with the removal of the maxillary right first molar. A total of 159 pairs of original and processed casts were input into the Generative Adversarial Networks (GANs) for training. In validation, 10 sets of processed casts were input into the AI system, and 10 AI-designed teeth were generated through backpropagation. Individual AI-designed teeth were then superimposed onto each of the 10 original teeth, and the morphological differences in mean Hausdorff distance were measured. True reconstruction was defined as correct matching between the AI-designed and original teeth with the smallest mean Hausdorff distance. The ratio of true reconstruction was calculated as the Intersection-over-Union. The reconstruction performance of the AI system was determined by the Hausdorff distance and Intersection-over-Union., Results: Data of validation showed that the mean Hausdorff distance ranged from 0.441 to 0.752 mm and the Intersection-over-Union of the system was 0.600 (60%)., Conclusions: This study demonstrated the feasibility of AI in designing single-molar dental prostheses. With further training and optimization of algorithms, the accuracy of biomimetic AI-designed dental prostheses could be further enhanced., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Statement of Problem: Reports on digitally fabricated complete dentures are increasing. However, comprehensive evidence-based research on their cost-efficiency and patient-reported outcome measures (PROMs) is lacking., Purpose: The purpose of this systematic review was to compare the cost-effectiveness and PROMs between digitally and conventionally fabricated complete dentures., Material and Methods: An electronic search of publications from 2011 to mid-2023 was established using PubMed/Medline, EBSCOhost, and Google Scholar. Retrospective, prospective, randomized controlled, and randomized crossover clinical studies on at least 10 participants were included. A total of 540 articles were identified and assessed at the title, abstract, and full article level, resulting in the inclusion of 14 articles. Data on cost, number of visits, patient satisfaction, and oral health-related quality of life were examined and reported., Results: The systematic review included 572 digitally fabricated complete dentures and 939 conventionally fabricated complete dentures inserted in 1300 patients. Digitally fabricated complete dentures require less clinical time with a lower total cost, despite higher material costs compared with the conventional fabrication technique. Digitally and conventionally fabricated complete dentures were found to have significant effects on mastication efficiency, comfort, retention, stability, ease of cleaning, phonetics, and overall patient satisfaction, as well as social disability, functional limitation, psychological discomfort, physical pain, and handicap., Conclusions: Digitally fabricated complete dentures are more cost-effective than conventionally fabricated dentures. There are various impacts of conventionally and digitally fabricated complete dentures on PROMs, and they are not better than one another., (Copyright © 2023 Editorial Council for The Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Objective: The purpose of this study was to evaluate the use of magnifying loupes (×2.5) on the quality of tooth preparation for complete coverage crowns; performed by predoctoral students using an objective and quantitative digital method., Materials and Methods: Forty-two predoctoral students were randomly assigned into 2 groups to perform tooth preparation for a complete coverage crown on a mandibular first molar in a manikin, with and without the use of magnifying loupes. All preparations were digitally evaluated by PrepCheck 3.0 (Dentsply Sirona). Parameters including tooth reduction, total occlusal convergence (TOC), undercut, margin quality and surface quality were assessed. Continuous data were analysed using Paired t-tests or Wilcoxon Signed Ranks tests. Ordinal data were analysed by McNemer's tests. To further detect the majority pattern ( > 50%) in each group (with and without loupes), one-sample t-test or one-sample Wilcoxon Signed Rank test was performed. The level of significance was set at p = .001 after Bonferroni adjustments for multiple testing., Results: No significant differences in the measured outcomes were found between the groups with or without the use of magnifying loupes (p > .002). The majority (>50%) of both groups had no undercuts (99.3% and 99.4% both p < .001) and the preparation type was within tolerance (81.6% and 85.3%, both p < .001) with acceptable margin (86.4% and 86.3%, both p < .001) and acceptable surface quality (99.0% and 99.1%, both p < .001). However, the majority of both groups underprepared occlusally (96.0% and 95.4%, both p < .001) and axially (65.3% and 67%, both p < .001). Only 30.0%-42.1% of the participants achieved the TOC within 0-20°., Conclusions: Within the limitations of this study, the use of magnification loupes does not appear to significantly improve the quality of tooth preparation for complete coverage crown. The TOC was also found to be overprepared and occlusally underprepared., (© 2023 The Authors. European Journal of Dental Education published by John Wiley & Sons Ltd.)

Objective: This in vitro study aimed to investigate enamel wear against 3 monolithic ceramics using 2 methods of measurement., Methods: Three groups of standard flat monolithic ceramic specimens including zirconia-reinforced lithium silicate glass (Vita Suprinity, VITA Zahnfabrik), yttria-stabilised tetragonal zirconia (Lava Esthetic Zirconia), and lithium disilicate glass (IPS e.max Press, Ivoclar Vivadent) were prepared, with human enamel used as the control group. Each specimen was subjected to the 2-body wear test at 49 N for 250,000 cycles. Enamel antagonists were evaluated with micro-computed tomography (CT) and intra-oral scanner, allowing 3-dimensional images of vertical wear and volumetric loss of enamel antagonists to be calculated. One-way analysis of variance followed by Student-Newman-Keuls post hoc tests were used to examine the differences in vertical wear/volumetric loss amongst the groups. Paired t tests and intra-class correlations were used to compare vertical wear/volumetric loss between the micro-CT and intra-oral scanner groups., Results: No significant difference in vertical wear was found amongst all groups. More volumetric loss was found in all test groups than in the control group (P < .001), but no significant difference was found amongst the test groups. There was a moderate positive correlation (r = 0.535, P = .033) between the vertical wear and volumetric loss. No significant difference between the 2 methods of measurement was found., Conclusions: Monolithic ceramics induce more enamel wear than natural teeth. Both micro-CT and intra-oral scanners can be used for measuring tooth wear with similar performance., Competing Interests: Conflict of interest None disclosed., (Copyright © 2022 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: To explore and analyse the perspective of patients undergoing and recovering from nasopharyngeal carcinoma (NPC) therapy., Methods: Thirty-three NPC patients at different stages of treatment were enroled. Seven were actively undergoing treatment, 13 were immediately post-treatment, and 13 were long-term. Patients were interviewed using a structured questionnaire based on a review of the literature that covered different phases of their treatment journey. The interview was recorded and transcribed for qualitative data analysis using a thematic inductive-deductive approach., Results: Three main domains embracing aspects of NPC patients' experiences were identified; side effects, psychosocial well-being, and the role and support of healthcare workers. Side effects were experienced orally, locally, and systemically. Oral side effects (oral mucositis, xerostomia, altered taste, dysphagia) were the most significant challenge experienced by NPC patients. Locally, skin injury (desquamation, fibrosis, darkening of the skin, erythema, pruritus, and swelling around the neck region) and hair loss, resolved after cessation of therapy. Systemic side effects from the treatment were related to general weakness, weight loss and nausea. The psychosocial well-being of NPC patients was influenced by a range of issues including support (healthcare workers and family), pain management, functional limitations, nutritional needs, perceived level of information, emotion, and finances., Conclusion: NPC patients were significantly impacted based on the diagnosis, treatment and recovery phase affecting them locally, systemically, and psychologically. The role of family and healthcare staff was also influential in the overall treatment experience, and they have key roles to play in facilitating patients along their treatment journey., Clinical Significance: Oral and general side effects from NPC treatment have significant impact on patients physical and emotional well-being. It is important for healthcare providers to have insights of these so as to understand and support patients during their treatment journey and recovery and be able to empathetically facilitate their clinical management., 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. Published by Elsevier Ltd.)

Purpose: To determine and compare the accuracy and reliability of shade matching using the conventional and smartphone virtual methods., Materials and Methods: A phantom head with both maxillary central incisors removed was set up. A central incisor of various standard shades was inserted into the phantom head. Five undergraduate and five postgraduate students were asked to select the closest shade to match the central incisor using the Vita Classic shade guide. The procedure was then repeated using images taken by a smartphone. Each technique was repeated three times. Differences in accuracy of shade matching between the two techniques for every shade tab and between undergraduate and postgraduate dental students were compared using chi-square statistical analysis. The P value was set at .001. Differences in intra-rater and inter-rater reliability between the two techniques and among the three sessions were compared using paired t test and analysis of variance (ANOVA), respectively, with a P value of .05. The reliability of both techniques was further measured using Cohen kappa statistical test., Results: The smartphone virtual shade-matching technique showed significantly higher accuracy in shade matching with most of the tested shade tabs than the conventional method (P < .001), irrespective of observers' clinical experience. Higher repeatability was found in the virtual technique than the conventional technique, with higher intra-rater and inter-rater reliability observed., Conclusion: Smartphone virtual shade matching showed better accuracy and reliability than the conventional method and could be used as an alternative shade-matching method.

Objectives: This study utilised an Artificial Intelligence (AI) method, namely 3D-Deep Convolutional Generative Adversarial Network (3D-DCGAN), which is one of the true 3D machine learning methods, as an automatic algorithm to design a dental crown., Methods: Six hundred sets of digital casts containing mandibular second premolars and their adjacent and antagonist teeth obtained from healthy personnel were machine-learned using 3D-DCGAN. Additional 12 sets of data were used as the test dataset, whereas the natural second premolars in the test dataset were compared with the designs in (1) 3D-DCGAN, (2) CEREC Biogeneric, and (3) CAD for morphological parameters of 3D similarity, cusp angle, occlusal contact point number and area, and in silico fatigue simulations with finite element (FE) using lithium disilicate material., Results: The 3D-DCGAN design and natural teeth had the lowest discrepancy in morphology compared with the other groups (root mean square value = 0.3611). The Biogeneric design showed a significantly (p < 0.05) higher cusp angle (67.11°) than that of the 3D-DCGAN design (49.43°) and natural tooth (54.05°). No significant difference was observed in the number and area of occlusal contact points among the four groups. FE analysis showed that the 3D-DCGAN design had the best match to the natural tooth regarding the stress distribution in the crown. The 3D-DCGAN design was subjected to 26.73 MPa and the natural tooth was subjected to 23.97 MPa stress at the central fossa area under physiological occlusal force (300 N); the two groups showed similar fatigue lifetimes (F-N curve) under simulated cyclic loading of 100-400 N. Designs with Biogeneric or technician would yield respectively higher or lower fatigue lifetime than natural teeth., Significance: This study demonstrated that 3D-DCGAN could be utilised to design personalised dental crowns with high accuracy that can mimic both the morphology and biomechanics of natural teeth., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Objective: To seek dentine analogue materials in combined experimental, analytical, and numerical approaches on the mechanical properties and fatigue behaviours that could replace human dentine in a crown fatigue laboratory test., Methods: A woven glass fibre-filled epoxy (NEMA grade G10; G10) and a glass fibre-reinforced polyamide-nylon (30% glass fibre reinforced polyamide-nylon 6,6; RPN) were investigated and compared with human dentine (HD). Flexural strength and elastic modulus (n = 10) were tested on beam-shaped specimens via three-point bending, while indentation hardness (n = 3) was tested after fracture. Abutment substrates of G10, RPN and HD were prepared and resin-bonded with monolithic lithium disilicate crowns (n = 10), then subjected to wet cyclic loading in a step-stress manner (500 N initial load, 100 N step size, 100,000 cycles per step, 20 Hz frequency). Data were statistically analysed using Kruskal-Wallis one-way ANOVA followed by post-hoc comparisons (α = 0.05). Survival probability estimation was performed by Mantel-Cox Log-Rank test with 95% confidence intervals. The fatigue failure load (FFL) and the number of cycles until failure (NCF) were evaluated with Weibull statistics. Finite Element Models of the fatigue test were established for stress distribution analysis and lifetime prediction. Fractographic observations were qualitatively analysed., Results: The flexural strength of HD (164.27 ± 14.24 MPa), G10 (116.48 ± 5.93 MPa), and RPN (86.73 ± 3.56 MPa) were significantly different (p < 0.001), while no significant difference was observed in their flexural moduli (p = 0.377) and the indentation hardness between HD and RPN (p = 0.749). The wet cyclic fatigue test revealed comparable mean FFL and NCF of G10 and RPN to HD (p = 0.237 and 0.294, respectively) and similar survival probabilities for the three groups (p = 0.055). However, RPN promotes higher stability and lower deviation of fatigue test results than G10 in Weibull analysis and FEA., Significance: Even though dentine analogue materials might exhibit similar elastic properties and fatigue performance to human dentine, different reliabilities of fatigue on crown-dentine analogues were shown. RPN seems to be a better substrate that could provide higher reliability and predictability of laboratory study results., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Purpose: To investigate the error accumulation and distribution through various stages of the digital workflow for complete-arch implant-supported framework fabrication., Materials and Methods: A resin model of edentulous maxilla with 6 dental implants was scanned using an intraoral scanner for 10 times (Complete-digital group). Ten conventional gypsum casts were made and digitized by a laboratory scanner (Analogue-digital group). Five implant frameworks were designed and milled using CAD-CAM technique for each workflow. Inter-implant distances and angles of the resin model (reference) and frameworks were measured by a coordinate measuring machine, while the scans and virtual frameworks were examined by an inspection software. Effect of type of workflow and the individual stage on the accuracy of the frameworks were analysed by Two-way ANOVA., Results: The expanded uncertainty of both workflows was ~150 μm and ~ 0.8°. The accuracy of the CAD stage was the highest. In the complete-digital workflow, the greatest distortion was found in the data acquisition stage, while in the analogue-digital workflow, it was found in the CAM stage. Compared with the analogue-digital group, the complete-digital group showed a significant higher precision in the first quadrant, but lower trueness in the second quadrant in data acquisition, and a significantly lower precision in the second quadrant at the CAD stage., Conclusions: Linear distortions of the complete-digital and analogue-digital workflows were clinically acceptable, while angular distortions were not. Distortions were generally derived from data acquisition and CAM stage. The CAD precision depended on the distortions derived from data acquisition. The complete-digital workflow was not as accurate as the analogue-digital in complete-arch implant rehabilitation., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Objective: To assess the marginal and bacterial microleakage in zirconia and CAD-CAM or cast Co-Cr implant abutments., Methods: Sixty-four conical connection implants with their respective abutments were divided into four groups (Co-Cr (milled, laser-sintered, and cast) and Zirconia (milled)). All specimens were subjected to a chewing simulation and thermocycling. After aging process, specimens were submerged in a 0.2% methylene blue solution with Porphyromonas gingivalis (P.g) for 48 h. The marginal microleakage was measured using a 40× optical microscopy at the internal part of the implant, and when positive microleakage was observed, a DNA isolation with a polymerase chain reaction (PCR) test was used. The microbiological assessment was based on colony forming units (CFUs)., Results: Thirty (47%) implant-abutments presented microleakage and the PCR was performed on those specimens (1 Zirconia, 1 Co-Cr milled, 14 Co-Cr laser-sintered and 14 cast). Seven specimens (1 Co-Cr laser-sintered and six cast) presented values below the PCR detection limit (< 100 CFUs). The lowest CFUs count occurred in the Co-Cr milled group (5.17E+02 CFUs/ml) followed by zirconia (7.70E+03 CFUs/ml). The Co-Cr cast (9.39E+03 CFUs/ml) and laser-sintered (2.4E+05 CFUs/ml) groups had higher bacterial count. The CFU count comparison performed between Co-Cr cast and laser-sintered resulted in a statistically significant differences in favor of Co-CrCL (p < .05)., Conclusions: The abutment material and fabrication technique affected the implant-abutment microleakage. Although the CAD-CAM abutments presented favorable results, all tested groups presented microleakage., (© 2022 The Authors. Clinical Oral Implants Research published by John Wiley & Sons Ltd.)

This study aimed to compare the occlusal morphology and fracture behavior of lithium disilicate ceramic dental crowns on 12 human participants' premolar #45 designed by a knowledge-based AI (CEREC, biogeneric individual function, BI) and different human personnel (experienced technician, TD, and trained dental students, AD) using CAD software. Digital datasets of crown design were best-fit aligned with the original teeth to evaluate profile and volume discrepancies of the occlusal morphology, and difference in the functional cuspal angle. Milled and sintered lithium disilicate crowns were resin-luted to 3D-printed dental casts and were subjected to axial load-to-fracture test. The fracture loads and failure modes were recorded and examined. Repeated measures ANOVA with LSD post-hoc test, Kruskal-Wallis test, Pearson's correlation coefficient, paired t-test, and chi-square exact test were used for statistical analyses (α = 0.05). BI-generated crowns showed the highest occlusal profile discrepancy (0.3677 ± 0.0388 mm), whereas human-CAD designed crowns showed higher conformity to the original teeth (0.3254 ± 0.0515 mm for TD, 0.3571 ± 0.0820 for AD; z-difference method; p < 0.001). Cusp angle values were significantly different in all groups except BI and TD (54.76 ± 3.81° for the original teeth, 70.84 ± 4.31° for BI, 67.45 ± 5.30° for TD, and 62.30 ± 7.92° for AD; p < 0.001). Although all three groups of crown designs could achieve clinically acceptable fracture resistance (1556.09 ± 525.68 N for BI, 1486.00 ± 520.08 N for TD, 1425.77 ± 433.34 for AD; p = 0.505) such that no significant difference in fracture strength was found, most crowns presented catastrophic bulk fracture that was not clinically restorable because of the substrate fracture. Group BI had a significantly higher percentage of restorable substrate damage than TD (p = 0.014) and AD (p < 0.001). In conclusion, in designing lithium disilicate dental crown, CAD design with human may be better than knowledge-based AI., (Copyright © 2022 Elsevier Ltd. All rights reserved.)

The aim of this study was to investigate the effects of supporting dies with different mechanical properties on the fracture strengths and failure modes of monolithic zirconia crowns, and identify a suitable die material for testing high-strength ceramic restorations. Thirty six dies from teeth, porous titanium and composite-resin with 36 zirconia crowns were fabricated based on 3D model. Crowns were cemented, then underwent load-to-fracture testing. Fractographic analysis was performed with scanning electron microscopy, and finite element analysis was made. During loading, a high stress concentration zone formed near the loading point and on surface of die. Cracks generated on failure penetrated the crown and extended to die in 9 teeth group specimens, while composite-resin samples exhibited fracture of both crowns and dies. All dies remained intact in porous titanium group. Fracture mode was undistinguishable in all groups. It was concluded that porous titanium appears suitable as die material for dental restorations with high fracture strength.

Objectives: To compare 2 implant scan bodies with different geometry on the accuracy of the virtual alignment process in the digital workflow., Materials and Methods: A master model of the edentulous maxilla with 6 implants and multiunit abutments (MUA) inserted was fabricated. Six dome-shaped and cuboidal scan bodies were mounted on the MUAs, respectively, and consecutively scanned by a laboratory scanner 10 times. The original scans were imported to a dental-specific CAD software and virtually aligned with the default CAD model in the implant library. Thus, 10 aligned models were created. Both the original scans and the aligned models were evaluated by an inspection software for deviation of the scan body surfaces, the centroids of scan body and MUA, the scan body center-axis, and the inter-MUA distances/angles. The two-sample T-test/Mann-Whitney U test were used to analyze the data with the level of significance set at 0.05., Results: The cuboidal group showed significant greater deviations of the model surface (13.9 µm vs. 10.7 µm) and the MUA centroids (31.7 µm vs. 22.8 µm) but smaller deviation of the inter-MUA angle (0.047° vs. 0.070°) than those of the dome-shaped group (p < .05). No significant differences in the deviation of scan body centroids, center-axis, and the inter-MUA distances between the 2 groups were found., Conclusions: Virtual alignment of implant scan body affected the accuracy of the digital workflow for complete-arch implant-supported prostheses (up to ~30 µm/0.09°). Different geometries of the implant scan body could also influence the transfer accuracy in the CAD process., (© 2022 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.)

Statement of Problem: Lithium disilicate (LD) is a popular dental ceramic and has been a focus of dental research. Nevertheless, a quantified literature analysis focusing on the research of lithium disilicate is lacking., Purpose: The purpose of this bibliometric analysis was to review the progress of research into lithium disilicate in dentistry, including the identification of contributing researchers, organizations, countries or regions, journals, and the analysis of high-impact keywords and research trending., Material and Methods: The search was carried out within the topic field of the Web of Science (WoS) database, collecting publications related to LD from between 1996 and 2019. Metadata including the titles, abstracts, keywords, authors, affiliations, countries or regions, and references were extracted. Bibliometric indicators in terms of documents, authors, journals, and keywords were analyzed., Results: Between 1996 and 2019, the dental research on LD trended upward. Scholars in the United States, Germany, Switzerland, and Brazil actively participated in the research on LD, and publications from the United States had the most citations. The Journal of Prosthetic Dentistry and Dental Materials were the major contributing journals. High-impact terms could be categorized into types of restorative material, types of prostheses, and properties or techniques of materials. Co-occurrence and relative normalized citation analysis of keywords highlighted several research interests, such as comparison studies between LD and zirconia, computer-aided design and computer-aided manufacturing (CAD-CAM) techniques, and the performance of complete coverage LD restorations., Conclusions: With the global upsurge in research on lithium disilicate, extensive collaborations and citations have been noted among authors, institutions, and countries or regions. Research hotspots include types of restorative material, types of prostheses, and properties or techniques of materials., (Copyright © 2020 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

The aim of this in vitro study was to investigate the microgaps at the implant-abutment interface when zirconia (Zr) and CAD/CAM or cast Co-Cr abutments were used., Methods: Sixty-four conical connection implants and their abutments were divided into four groups (Co-Cr (milled, laser-sintered and castable) and Zirconia (milled)). After chewing simulation (300,000 cycles, under 200 N loads at 2 Hz at a 30° angle) and thermocycling (10,000 cycles, 5 to 50 °C, dwelling time 55 s), the implant-abutment microgap was measured 14 times at each of the four anatomical aspects on each specimen by using a scanning electron microscope (SEM). Kruskal-Wallis and pair-wise comparison were used to analyze the data (α = 0.05)., Results: The SEM analysis revealed smaller microgaps with Co-Cr milled abutments (0.69-8.39 μm) followed by Zr abutments (0.12-6.57 μm), Co-Cr sintered (7.31-25.7 μm) and cast Co-Cr (1.68-85.97 μm). Statistically significant differences were found between milled and cast Co-Cr, milled and laser-sintered Co-Cr, and between Zr and cast and laser-sintered Co-Cr ( p < 0.05)., Conclusions: The material and the abutment fabrication technique affected the implant-abutment microgap magnitude. The Zr and the milled Co-Cr presented smaller microgaps. Although the CAD/CAM abutments presented the most favorable values, all tested groups had microgaps within a range of 10 to 150 μm.

Material research in tissue engineering forms a vital link between basic cell research and animal research. Periodontal ligament cells (PDLCs, P) from the tooth have an osteogenic effect, whereas endothelial progenitor cells (EPCs, E) assist in neovascularization. In the present study, the interaction of PDLCs and EPCs with Tantalum (Ta, I) discs, either alone (IP or IE group) or in 1:1 (IPE) ratio was explored. Additionally, surface analysis of Ta discs with respect to different types and cycles of sterilization and disinfection procedures was evaluated. It was observed that Ta discs could be used for a maximum of three times, after which the changes in properties of Ta discs were detrimental to cell growth, irrespective of the type of the protocol. Cell-Disc's analysis revealed that cell proliferation in the IE group at day 6 and day 10 was significantly higher ( p < 0.05) than other groups. A cell viability assay revealed increased live cells in the IPE group than in the IP or IE group. Similarly, adhesion and penetration of cells in the IPE group were not only higher, but also had an increased thickness of cellular extensions. RT-PCR analysis revealed that on day 8, both osteogenic (ALP, RUNX-2, and BSP) and angiogenic genes (VEGFR-2, CD31) increased significantly in the IPE group as compared to the IP or IE groups ( p < 0.05). In conclusion, Ta discs promoted cellular proliferation and increased osteogenic and angiogenic activity by augmenting RUNX-2 and VEGFR-2 activity.

Background: The fit of implant-supported prostheses is of prime importance for the long-term success of implant therapy., Purpose: This systematic review aimed to evaluate recent evidence on current techniques for assessing implant-framework misfit, its associated strain/stress, and whether these misfits are related to mechanical, biological, and clinical consequences., Materials and Methods: An electronic search for publications from January 2010 to October 2020 was performed using the Pubmed, Embase, Web of Science, and Cochrane Library databases with combined keywords on implant-framework misfit assessments and related clinical complications. Inclusion and exclusion criteria were applied. After full-text analyses, data extraction was implemented on current techniques of misfit assessment and the relationship between the misfit and the induced strain/stress., Results: A total of 3 in vivo and 92 in vitro studies were selected, including 47 studies on quantifying the degree of implant-framework misfit with dimensional techniques, 24 studies measuring misfit-induced strain/stress with modeling techniques, and 24 studies using both methods. The technical details, advantages, and limitations of each technique were illustrated. The correlation between the implant-framework misfit and the induced strain/stress has been revealed in vitro, while that with the biological complications and implant/prostheses failure was weak in clinical studies., Conclusions: Dimensional and modeling techniques are available to measure the implant-framework misfit. The passivity of implant-supported fixed prostheses appeared related to the induced strain/stress, but not the clinical complications. Further studies combining three-dimensional (3D) assessments using dimensional and modeling techniques was needed., (© 2020 Wiley Periodicals LLC.)

Background: Conventional freehand immediate placement of dental implants is technically challenging in the jaw reconstructive surgery. Computer-aided surgery might be the best solution, however, there has not been any standard approach to ensure the accuracy and efficiency of simultaneous dental implants in fibula flap jaw reconstruction., Purpose: We aim to evaluate the clinical outcome of simultaneous dental implant in fibula flap using the "three-in-one" patient-specific surgical guide (3-in-1-PSSG) in an open-label, prospective, single-arm, and single-center clinical trial., Materials and Methods: A novel computer-aided designed and three-dimensional (3D) printed 3-in-1-PSSG, which contains functions of fibula segmentation, surgical plate positioning and implant placement, was used to facilitate the reconstructive surgery and simultaneous dental implant placement. The intraoperative success of dental implant placement, implant survival rate and accuracy of dental implant placement were reported., Results: From November 2018 to June 2020, 15 consecutive patients with 48 dental implants were enrolled in this study. Fifteen 3-in-1-PSSGs were fabricated with a mean number of dental implants per guide of 3.2 ± 1.5. The intraoperative success rate of this approach was 14 out of 15. With an average follow-up period of 40 weeks, the overall implant survival rate was 83.3% (40/48). Eight implants were removed due to two fibula flap failures. The mean deviation at the implant platform and implant apex were 2.8 mm (interquartile range [IQR]: 1.9-3.4) and 3.2 mm (IQR: 2.0-4.6), and the angular deviation was 2.5° (IQR: 1.1-6.8)., Conclusions: Our preliminary data indicated that the 3D printed 3-in-1-PSSG facilitated simultaneous dental implant in fibula flap jaw reconstruction with a favorable intraoperative success and short-term clinical outcome. It might be a viable alternative to allow one-step immediate oral rehabilitation in patients underwent jaw reconstruction with free flaps. Long-term results with a larger sample size are warranted., (© 2020 Wiley Periodicals LLC.)

Sodium hypochlorite (NaOCl), an effective endodontic irrigant against Enterococcus faecalis (EF), is harmful to periapical tissues. Natural pineapple-orange eco-enzymes (M-EE) and papaya eco-enzyme (P-EE) could be potential alternatives. This study aimed to assess the antimicrobial efficacy of M-EE and P-EE at different concentrations and fermentation periods against EF, compared to 2.5% NaOCl. Fermented M-EE and P-EE (3 and 6 months) at various concentrations were mixed with EF in a 96-well plate incubated for 24 h anaerobically. Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of M-EE and P-EE were determined via EF growth observation. EF inhibition was quantitatively measured and compared between different irrigants using the one-way analysis of variance (ANOVA), and different fermentation periods using the independent-samples T-test. M-EE and P-EE showed MIC at 50% and MBC at 100% concentrations. There was no significant difference in antimicrobial effect when comparing M-EE and P-EE at 50% and 100% to 2.5% NaOCl. P-EE at 6 months fermentation exhibited higher EF inhibition compared to 3 months at concentrations of 25% ( p = 0.017) and 0.78% ( p = 0.009). The antimicrobial properties of M-EE and P-EE, at both 100% and 50% concentrations, are comparable to 2.5% NaOCl. They could therefore be potential alternative endodontic irrigants, but further studies are required.

Objectives: This study was conducted to examine the tooth wear status of nasopharyngeal-carcinoma (NPC) patients who had received radiotherapy at least 5-year previously, and to investigate the salivary parameters that may be associated with the tooth wear., Methods: Tooth wear status of NPC survivors were clinically assessed using the Exact Tooth Wear Index. A tooth was graded to have severe wear when more than one-third of its buccal/occlusal/lingual surface had dentine loss. At the subject-level, percentages of anterior/posterior/all teeth with severe wear were calculated. Age, number of teeth, flow-rate/buffering capacity/pH of stimulated whole (SWS) and parotid (SPS) saliva's were collected. Correlation and multiple-linear regression tests were performed at the significance level α = 0.05., Result: Sixty-eight participants (mean age of 60.0 ± 8.9), 697 anterior and 686 posterior teeth were examined with a mean of 10-years post-radiotherapy. Severe tooth wear was found in 63 (92.6 percent) participants, 288 anterior and 83 posterior teeth. The mean percentage of anterior/posterior/all teeth with severe wear were 42.3 ± 28.1, 14.5 ± 19.9 and 30.0 ± 21.7. Anterior teeth, particularly the incisal surface of central incisors were most affected. The mean flow-rate of SWS and SPS were 0.1 ± 0.1 ml/min and 0.03 ± 0.07 ml/min respectively. Thirty (44.1 percent) and 48 (70.6 percent) participants were found to have low/no buffering capacity of SWS and SPS respectively. Multiple-regression analyses revealed the SWS flow-rate was associated with the percentage of anterior teeth with severe wear (p=0.03)., Conclusion: Anterior tooth wear is a significant dental problem among NPC survivors and was associated with hypo-salivation., Clinical Significance: Patients with hypo-salivation should be being monitored for tooth wear particularly on the anterior teeth., 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 © 2020 Elsevier Ltd. All rights reserved.)

Objectives: To evaluate the reproducibility of complete arch scanning with multiple implant scan bodies using a laboratory scanner., Methods: A master model of edentulous maxillary arch with 6 implants was fabricated. PEEK scan bodies were inserted into the model and consecutively scanned using a dental laboratory scanner (N = 10, Group C). Another 10 scans were performed with each scan body detached and reinserted into the same site between each scan (Group CR). The last group of scanning was performed with the scan bodies detached and randomly repositioned between each scan (N = 10, Group RR). Virtual models were created and the inter-implant distances and angles were measured using an inspection software. Accuracy of the complete arch scans was calculated and compared using Two-Way ANOVA (⍺ = 0.05)., Results: Significant greater distance distortion was found in CR (27.6 ± 18.9 μm) and RR (34.2 ± 25.0 μm). No significant difference in angular distortion was found among 3 groups. The greatest distance distortion was found in the anterior and cross-arch region of the arch. The smallest angular distortion was found in the first scanned sextant, with increasing distortion along the scanning path of the arch. The distance precision was significantly reduced in group CR and RR, while the angular precision was significantly reduced in group RR only., Conclusion: Reproducibility of complete arch scanning was significantly affected by repositioning of the scan bodies using a laboratory scanner. Repeated and random repositioning of the scan bodies would decrease the reproducibility of the spatial position and angle of the virtual implant. The distortion appeared to be small and within the clinical tolerance., Clinical Significance: High-precision transfer of the implant information from intra-oral environment to dental laboratory is a prerequisite for the success of implant-supported prosthesis. Although laboratory scanners seem to be accurate, their accuracy is also affected by the precision and attachment procedure of the implant scan bodies and that has always been overlooked., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Introduction: Candida albicans possesses the ability to switch rapidly between yeast to hyphal forms. Hyphal formation is a remarkable pathogenic characteristic, which allows C. albicans to invade into host cells., Objectives: This study was to investigate the role of the C. albicans SAP9 gene in hyphal formation and invasion ability., Methods: The morphology of fungal cells in the hyphal-inducing liquid media (YPD+10% fetal bovine serum) was observed by the microscopy. And the morphology of the colony on solid agar plates of YPD+10% fetal bovine serum was photographed by the digital camera. The mRNA expressions of hypha-associated genes in serum medium were also analyzed by real time PCR. Then for the interaction between C. albicans and oral epithelial cells, endocytosis essay, invasion essay and damage assay were performed to compare the differences between the sap9Δ/Δ mutant strain and wild type strain., Results: Compared with the wild type strain, the sap9Δ/Δ mutant strain exhibited a deficient yeast-to-hyphal morphological transition under serum hyphal-inducing conditions. Furthermore, the SAP9 knockout strain revealed a significant down-regulation of the expression of EFG1 (~40%), which is a transcription factor gene that mediates hyphae formation in C. albicans. Compared with the wild type strain, a 70% reduction in the endocytosis of the sap9Δ/Δ mutant strain by host cells was observed, as well as a 25% attenuation of active penetration and a 40% attenuation of host cell damage (P <0.05)., Conclusions: Our data strongly suggests that C. albicans Sap9 is a potential hyphal-associated factor that responds to serum hyphal-inducing stimuli via a cAMP-protein kinase A pathway mediated by EFG1, and contributes to the process of invasion of Candida into the epithelial cells, leading to host cell damage., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Purpose: To investigate the correlation of anterior overbite with the sagittal root position (SRP) and buccal bone thickness (BBT) of the maxillary anterior teeth., Methods: Cone-beam computed tomography (CBCT) data of southern Chinese patients who underwent CBCT examinations between November 2016 and December 2016 were collected. The anterior overbite was the predictor variable while the SRP and the BBT at 4 mm apical to the cementoenamel junction (CEJ-4) and midpoint of the root of the maxillary anterior teeth were set as the primary and secondary outcome variables, respectively. All measurements were done by two calibrated examiners. Correlations between variables were analyzed by the Spearman's correlation coefficient. The significance level was set at P < 0.05., Results: CBCT data of 146 patients (65 men and 81 women) with a mean age of 44.2 ± 13.4 years were analyzed, and of the 876 maxillary anterior teeth evaluated, 9.8% were presented with deep overbites. Most of roots of the anterior teeth (94.9%) were positioned against the buccal cortical plate, of which, in 63.8% of them the apex was not covered by bone along the long axis of the tooth. The mean BBT at CEJ-4 was 0.89 mm at the central incisor, 0.85 mm at the lateral incisor and 0.84 mm at the canine. The overbite was positively correlated with SRP Class I subtypes and the BBT at CEJ-4 (P < 0.05)., Conclusion: Deep overbite was more frequently accompanied by bone fenestration in the anterior maxillary areas.

Aim: The aim of the present study was to investigate the initial stem cell and pre-osteoblast cell adhesion and oxidative response on zirconia in comparison with titanium., Methods: Human dental pulp stem cells (DPSC) and murine pre-osteoblasts (MC3T3-E1) cells were cultured on zirconia and titanium surfaces, and at 3-, 12-, and 24-hour intervals, cell viability and morphology were determined with tetrazolium based colorimetric assay, scanning electron microscopy, and immunofluorescence analysis. The in situ reactive oxygen species level of both cells on each material surface was examined after 24-hour culture., Results: Both DPSC and MC3T3-E1 cells revealed comparable morphological features during 24-hour cell adhesion processes, with cells continued expanding of cell size and increasing of cell viability on titanium and zirconia surfaces during 24-hour culture. Zirconia demonstrated relatively higher mean cell viability compared to titanium within 24-hour culture, with significantly higher DPSC viability at 12 hours after seeding (P < 0.05). Relatively higher mean reactive oxygen species levels in both DPSC and MC3T3E1 were found on zirconia surfaces after 24-hour culture compared to titanium., Conclusions: From the results, zirconia as a potential dental implant substrate demonstrated equivalent or better initial cellular responses compared to titanium., (© 2019 John Wiley & Sons Australia, Ltd.)

Objectives: Tooth shade is crucial to patient satisfaction in aesthetic dentistry. Two-dimensional (2D) clinical photographs have been widely used to record patients' tooth shade for creation of beautiful smile. However, in the digital workflow, 3D virtual teeth models in open file format contain only mesh information with no colour. This paper describes the mapping of colour information from the intraoral photographs onto the virtual teeth model., Methods: Intraoral photographs of occlusal and buccal views were taken using digital single lens reflex (SLR) camera with macro lens and ring flash. Photographs were calibrated for its colour and white balance. Virtual models were generated by scanning teeth/stone casts using an intraoral/model scanner. Intraoral photographs were mapped onto the virtual model using the image-to-geometry registration method by locating corresponding feature points in the 2D and 3D images., Results: Virtual teeth models of dentate (with and without crowding) and partially dentate patients were mapped with intraoral photographs. The resultant models are open file format and can be viewed and manipulated in dental or generic CAD/CAM software. Moreover, RGB (Red Green Blue) colour information and error of registration can be retrieved., Conclusion: Image-to-geometry registration allows mapping of colour information in the 2D intraoral photographs on 3D virtual teeth models. The proposed method is applicable across scanning systems and the coloured model can be generated from stone casts and intraoral photographs., Clinical Significance: Virtual teeth model with colour information facilitates shade matching and creation of beautiful smile., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

With the discovery of endothelial progenitor cells (EPCs) in the late 1990s, a paradigm shift in the concept of neoangiogenesis occurred. The identification of circulating EPCs in peripheral blood marked the beginning of a new era with enormous potential in the rapidly transforming regenerative field. Overwhelmed with the revelation, researchers across the globe focused on isolating, defining, and interpreting the role of EPCs in various physiological and pathological conditions. Consequently, controversies emerged regarding the isolation techniques and classification of EPCs. Nevertheless, the potential of using EPCs in tissue engineering as an angiogenic source has been extensively explored. Concomitantly, the impact of EPCs on various diseases, such as diabetes, cancer, and cardiovascular diseases, has been studied. Within the limitations of the current knowledge, this review attempts to delineate the concept of EPCs in a sequential manner from the speculative history to a definitive presence (origin, sources of EPCs, isolation, and identification) and significance of these EPCs. Additionally, this review is aimed at serving as a guide for investigators, identifying potential research gaps, and summarizing our current and future prospects regarding EPCs.

Purpose: The aim of this study was to investigate and quantify the effect of preparation design parameters on a premolar restored with two different CAD/CAM ceramic crowns by three-dimensional finite element analysis (FEA)., Methods: A restored human first premolar was digitized by a micro-CT scanner and a 3D model was created by a medical image processing software (Mimics). Following segmentation, dentine and ceramic were extracted by a surface meshing software (3-matic). Models with different preparation designs with three convergence angles (6°, 12° and 20°) and two preparation heights (3.1mm and 4.1mm) were produced. Mesh generation for models was performed in IA-FEMesh software with a lithium disilicate glass ceramic (LD, E=95.9GPa) and a polymer-infiltrated ceramic (PIC, E=30.1GPa) as the restorative materials. A 5-mm diameter stainless steel hemisphere was employed as an indenter. Twelve models were analyzed numerically in Abaqus™., Results: The results indicated that preparation height was found to be a major factor affecting stress distribution in different components. In all models, the maximum principal stress of the ceramic crowns was found in contact area against the indenter. This stress was lesser in the longer abutment than the shorter one and it was greater for LD ceramic. Convergence angle had limited effect on stress distribution of ceramic crown in all models., Conclusions: The preparation height appeared to play a more important role in the stress distribution of ceramic crown than the convergence angle., (Copyright © 2018 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.)

Objectives: The purpose of this study was to estimate the fatigue life of premolars restored with two dental ceramics, lithium disilicate (LD) and polymer infiltrated ceramic (PIC) using the numerical method and compare it with the published in vitro data., Methods: A premolar restored with full-coverage crown was digitized. The volumetric shape of tooth tissues and crowns were created in Mimics ® . They were transferred to IA-FEMesh for mesh generation and the model was analyzed with Abaqus. By combining the stress distribution results with fatigue stress-life (S-N) approach, the lifetime of restored premolars was predicted., Results: The predicted lifetime was 1,231,318 cycles for LD with fatigue load of 1400N, while the one for PIC was 475,063 cycles with the load of 870N. The peak value of maximum principal stress occurred at the contact area (LD: 172MPa and PIC: 96MPa) and central fossa (LD: 100MPa and PIC: 64MPa) for both ceramics which were the most seen failure areas in the experiment. In the adhesive layer, the maximum shear stress was observed at the shoulder area (LD: 53.6MPa and PIC: 29MPa)., Significance: The fatigue life and failure modes of all-ceramic crown determined by the numerical method seem to correlate well with the previous experimental study., (Copyright © 2018 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.)

Background: Human periodontal ligament stem cells (hPDLSCs) have been shown to be a reliable source of mesenchymal stem cells (MSCs). On the other hand, rabbits have been commonly used in preclinical trials for musculoskeletal research. However, there is a lack of sufficient data on using rabbit periodontal ligament stem cells (rPDLSCs) for regenerative dentistry. This study, for the first time, comprehensively compared rPDLSCs against hPDLSCs in terms of clonogenicity, growth potential, multi-differential capacity and surface antigens., Methods: Periodontal ligament (PDL) was obtained from the rabbit and human teeth. rPDL and hPDL cells were isolated from PDL using enzymatic digestion method. After culturing for 2 weeks, the cells were first analyzed microscopically. STRO-1 + CD146 + PDLSCs were then sorted from PDL cells by fluorescence-activated cell sorting (FACS) followed by examination of CD34, CD45, CD90, vimentin and desmin markers. The cells were also evaluated by immunohistocytochemical and multi-differentiation potential tests. The clonogenicity and growth of PDL cells were analyzed by Independent T test and 2-way repeated measures ANOVA respectively., Results: rPDL cells were broader and less elongated as compared to hPDL cells. STRO-1 + CD146 + hPDLSCs were isolated from hPDL cells but not from the rPDL cells. Therefore, heterogeneous population of rabbit and human PDL cells were subsequently used for latter comparative studies. FACS analysis and immunohistocytochemistry revealed that rPDL cells were partially positive for STRO-1 as compared to hPDL cells. Furthermore, both rPDL cells and hPDL cells were positive for CD146, CD90, vimentin, and desmin, while negative for CD34 and CD45. No difference in clonogenicity between rPDL and hPDL cells was found (p > 0.05). The proliferative potential of rPDL cells displayed significantly slower growth as compared to hPDL cells (p < 0.05). Osteogenic, adipogenic, and chondrogenic differentiation potential was comparatively less in rPDL cells than that of hPDL cells, but the neurogenic differential potential was similar., Conclusion: Although rPDL cells manifested variable differences in expression of stem cell markers and multi-differential potential as compared to hPDL cells, they demonstrated the attributes of stemness. Further studies are also required to validate if the regenerative potential of rPDL cells is similar to rPDLSCs.

Accurate articulator-mounted casts are essential for occlusion analysis and for fabrication of dental prostheses. Although the axis orbital plane has been commonly used as the reference horizontal plane, some clinicians prefer to register the horizontal plane with a spirit level when the patient is in the natural head position (NHP) to avoid anatomic landmark variations. This article presents a digital workflow for registering the patient's horizontal plane in NHP on a virtual articulator. An orientation reference board is used to calibrate a stereophotogrammetry device and a 3-dimensional facial photograph with the patient in NHP. The horizontal plane can then be automatically registered to the patient's virtual model and aligned to the virtual articulator at the transverse horizontal axis level. This technique showed good repeatability with positional differences of less than 1 degree and 1 mm in 5 repeated measurements in 1 patient., (Copyright © 2018 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.)

Aim: The aim of the present study was to compare the accuracy of radiographic measurements for dental implants planning using cone-beam computed tomography (CBCT) and helical computed tomography (HCT)., Methods: Six pig ribs were wrapped by putty impression material, with radiographic markers placed. Two CBCT and an HCT were taken following the standard protocols. Twenty-five locations were selected, with vertical and horizontal dimensions measured using the default software, as well as on the processed HCT films by a digital caliper. The actual dimensions of the ribs measured by the digital caliper served as the control. Differences between radiographic dimensions and the actual dimensions were tested by two-way analysis of variance., Results: No differences were found between measurements made by CBCT and HCT images using the default software (P > 0.05). However, both measurements were statistically-significantly lower than the control (P < 0.001), and the mean difference was 0.3 mm. Measurements made on HCT films were statistically-significantly greater than the control (P < 0.001), and the mean difference was 0.5 mm., Conclusion: The accuracy of CBCT and HCT are similar, and both are reliable tools for implant planning. It is preferable to perform the planning using default software, rather than making direct measurements on films., (© 2016 John Wiley & Sons Australia, Ltd.)

Purpose: The aim of this study was to measure the mechanical properties and fatigue behavior of three contemporary used dental ceramics, zirconia Cercon(®) (ZC), lithium disilicate e.max(®) CAD (LD), and polymer-infiltrated ceramic Enamic(®) (PIC)., Methods: Flexural strength of each CAD/CAM ceramic was measured by three point bending (n=15) followed by Weibull analysis. Elastic modulus was calculated from the load-displacement curve. For cyclic fatigue loading, sinusoidal loading with a frequency of 8Hz with minimum load 3N were applied to these ceramics (n=24) using three point bending from 10(3) to 10(6) cycles. Fatigue limits of these ceramics were predicted with S-N fatigue diagram. Fracture toughness and Vickers hardness of the ceramics were measured respectively by single edge V-notch beam (SEVNB) and microindentation (Hv 0.2) methods. Chemical compositions of the materials׳ surfaces were analyzed by EDS, and microstructural analysis was conducted on the fracture surfaces by SEM. One-way ANOVA was performed and the level of significance was set at 0.05 to analyze the numerical results., Results: The mean flexural strength of ZC, LD, and PIC was respectively 886.9, 356.7, and 135.8MPa. However, the highest Weibull modulus belonged to PIC with 19.7 and the lowest was found in LD with 7.0. The fatigue limit of maximum load for one million cycles of ZC, LD, and PIC was estimated to be 500.1, 168.4, and 73.8GPa. The mean fracture toughness of ZC, LD, and PIC was found to be respectively 6.6, 2.8, and 1.4MPam(1/2), while the mean Vickers hardness was 1641.7, 676.7, and 261.7Hv. Fracture surfaces followed fatigue loading appeared to be smoother than that after monotonic loading., Conclusions: Mechanical properties of ZC were substantially superior to the two other tested ceramics, but the scattering of data was the least in PIC. The fatigue limit was found to be approximately half of the mean flexural strength for all tested ceramics., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Objectives: To compare the effects of four surface coating methods on resin to zirconia shear bond strength., Material and Methods: Eighty pre-sintered zirconia discs were prepared and randomly divided into five study groups according to the corresponding methods of surface treatments as follows: group C (control group, fully sintered without any surface treatment), group S (fully sintered and then sandblasted with silica coated alumina powder), group G (fully sintered and then coated with glazing porcelain followed by acid etching), group Si (pre-coated with silica slurry then fully sintered), and group Z (coated with zirconia particles and then fully sintered). The observation of surface morphology and elemental composition analysis were conducted by SEM and EDX. Self-adhesive resin cement stubs (diameter 3.6mm and height 3mm) were then bonded on the zirconia discs with a cylindrical shape. Both initial and artificial aged (including 30-day water storage, thermal cycling for 3000 and 6000 cycles) shear bond strengths were then evaluated., Results: All the tested coating methods showed significantly higher shear bond strengths than the control group, in both dry and aged conditions. Group S produced the strongest initial zirconia/resin bonding (19.7MPa) and the control group had the lowest value (8.8MPa). However, after thermal cycling, group Z exhibited the highest mean value. All the samples in the control group failed in the thermal cycling. Both different coating methods (p<0.001) and various aging treatments (p<0.001) produced significant influence on resin-zirconia shear bond strength., Conclusions: A reliable and durable resin zirconia bonding is vital for the longevity of dental restorations. Silica coating might be a reliable way in enhancing adhesion between resin and zirconia., (Copyright © 2013 Elsevier Ltd. All rights reserved.)