Retrospective study of patients with amelogenesis imperfecta treated with different bonded restoration techniques.

OBJECTIVE: The aim of this retrospective study was to evaluate clinical success and satisfaction of patients with amelogenesis imperfecta treated with three different types of bonded restorations at a university clinic. MATERIALS AND METHODS: One hundred fifty-four restorations in 15 subjects with mean age of 17.3 years (SD 8.2) were evaluated after treatment with three different types of bonded restorations: all ceramic enamel-dentin bonded restorations, prefabricated composite veneers, and direct composite resin restorations. A modified version of the Californian Dental Association system for quality evaluation of dental care and a questionnaire assessing patient satisfaction were used for classification. The restorations were evaluated with respect to patient satisfaction, esthetics, technical, and biological complications. RESULTS: Mean observation period for the restorations was 42.5 months (SD 35.6). All restorations were in place at the time of the examination. Surface and color calibration showed a success of 95% for the ceramic enamel-dentin bonded restorations, 44% for the direct composite resin restorations, and 0% for the prefabricated composite veneers. The same pattern was evident for anatomy and marginal integrity. The subjects reported a high degree of satisfaction with both the esthetics and function of their restorations. CONCLUSION: The results indicated that all ceramic restorations demonstrated the best results for patients with amelogenesis imperfecta.

Quality of Information Regarding Repair Restorations on Dentist Websites: Systematic Search and Analysis.

BACKGROUND: Repairing instead of replacing partially defective dental restorations represents a minimally invasive treatment concept, and repairs are associated with advantages over complete restoration replacement. To participate in the shared decision-making process when facing partially defective restorations, patients need to be aware of the indications, limitations, and advantages or disadvantages of repairs. Patients are increasingly using the internet to gain health information like this online. OBJECTIVE: We aimed to assess the quality of German-speaking dentist websites on repairs of partially defective restorations. METHODS: Three electronic search engines were used to identify German-speaking websites of dental practices mentioning repairs. Regarding information on repairs, websites were assessed for (1) technical and functional aspects, (2) comprehensiveness of information, and (3) generic quality and risk of bias. Domains 1 and 3 were scored using validated tools (LIDA and DISCERN). Comprehensiveness was assessed using a criterion checklist related to evidence, advantages and disadvantages, restorations and defects suitable for repairs, and information regarding technical implementation. Generalized linear modeling was used to assess the impact of practice-specific parameters (practice location, practice setting, dental society membership, and year of examination or license to practice dentistry) on the quality of information. An overall quality score was calculated by averaging the quality scores of all three domains and used as primary outcome parameter. Quality scores of all three domains were also assessed individually and used as secondary outcomes. RESULTS: Fifty websites were included. The median score of quality of information was 23.2% (interquartile range [IQR] 21.7%-26.2%). Technical and functional aspects (55.2% [IQR 51.7%-58.6%]) showed significantly higher quality than comprehensiveness of information (8.3% [IQR 8.3%-16.7%]) and generic quality and risk of bias (3.6% [IQR 0.0%-7.1%]; P<.001/Wilcoxon). Quality scores were not related to practice-specific parameters (P>.05/generalized linear modeling). CONCLUSIONS: The quality of German-speaking dentist websites on repairs was limited. Despite sufficient technical and functional quality, the provided information was neither comprehensive nor trustworthy. There is great need to improve the quality of information to fully and reliably inform patients, thereby allowing shared decision making.

Comportamento biomecânico das diferentes conexões entre restaurações monolíticas de zircônia e bases de titânio em próteses implanto-suportadas / Torque maintenance capacity, vertical misfit, load to failure and stress concentration in zirconia restorations cemented or notched to titanium bases

Este estudo avaliou a eficiência da pré-carga antes e após fadiga, desajuste vertical, carga para fratura e a concentração de tensões em restaurações de zircônia cimentadas ou acopladas a uma base de titânio (TB). Para isto, quarenta implantes foram incluídos em cilindros de polióxido de metileno (POM-DelrinDupont) e separados em dois grupos: restauração de zircônia cimentada em um TB ou acoplada em um TB experimental. Os corpos de prova tiveram o torque e o desajuste vertical avaliados antes e após a fadiga cíclica (200 N / 2 Hz / 2 x 106 ciclos / 37 °C). A carga até a fratura foi calculada em uma máquina universal de ensaios (1 mm / min, 1000 kgf) e as falhas foram avaliadas por estereomicroscopia e microscopia eletrônica de varredura. Modelos tridimensionais foram criados baseados na geometria dos espécimes laboratoriais e a concentração de tensão calculada pelo método dos elementos finitos. Os dados dos testes in vitro foram submetidos à análise de variância dois fatores e teste de Tukey (α = 0,5). As restaurações cimentadas apresentaram menor perda de torque (19,79 N.cm), menor desajuste vertical (3,77 µm), menor concentração de tensão na restauração (88,2 MPa) e maior carga de fratura (451,3 N) do que as restaurações acopladas (15,95 N.cm, 10,51 µm, 99,8 MPa e 390,8 N, respectivamente). Conclusão: A presença de uma camada de cimento entre a restauração e a base de titânio reduziu a suscetibilidade ao afrouxamento do parafuso do pilar, melhorou a resistência à carga compressiva e reduziu a concentração de tensão na restauração(AU)

The goal of this study was to evaluate the torque and vertical misfit before and after fatigue, the load to failure and the stress concentration of zirconia restorations cemented or notched to a titanium base (TB). Forty implants were included in Acetal Polyoxymethylene (POM-Delrin-Dupont) cylinders and divided in two groups: zirconia restoration cemented on a TB and zirconia restoration notched on an experimental TB. The specimens had their torque loosening and vertical misfit evaluated before and after cyclic fatigue (200 N / 2 Hz/ 2 x 106 cycles /37 °C). Load to failure was calculated in an universal testing machine (1 mm/min, 1000 kgf) and failures were evaluated by optical microscopy and scanning electron microscopy. Three-dimensional models were created based in the in vitro geometries and the stress concentration calculated using the finite element method. Data from the in vitro tests were submitted to two-way analysis of variance and Tukey test (α = 0.5). The cemented restorations presented less torque loosening (19.79 N.cm), lower vertical misfit (3.77 µm), lower stress concentration in the restoration (88.2 MPa) and higher fracture load (451.3 N) than notched restorations (15.95 N.cm, 10.51 µm, 99.8 MPa and 390.8 N, respectively). Conclusion: The presence of a cement layer between restoration and titanium base reduced the susceptibility to abutment screw loosening, improved the resistance to compressive load and reduced the stress concentration in the restoration(AU)

Oxidative Damage in Human Periodontal Ligament Fibroblast (hPLF) after Methylmercury Exposure.

Human exposure to mercury (Hg) is primary associated with its organic form, methylmercury (MeHg), through the ingestion of contaminated seafood. However, Hg contamination is also positively correlated with the number of dental restorations, total surface of amalgam, and organic mercury concentration in the saliva. Among the cells existing in the oral cavity, human periodontal ligament fibroblast (hPLF) cells are important cells responsible for the production of matrix and extracellular collagen, besides sustentation, renewal, repair, and tissue regeneration. In this way, the present study is aimed at investigating the potential oxidative effects caused by MeHg on hPLF. Firstly, we analyzed the cytotoxic effects of MeHg (general metabolism status, cell viability, and mercury accumulation) followed by the parameters related to oxidative stress (total antioxidant capacity, GSH levels, and DNA damage). Our results demonstrated that MeHg toxicity increased in accordance with the rise of MeHg concentration in the exposure solutions (1-7 µM) causing 100% of cell death at 7 µM MeHg exposure. The general metabolism status was firstly affected by 2 µM MeHg exposure (43.8 ± 1.7%), while a significant decrease of cell viability has arisen significantly only at 3 µM MeHg exposure (68.7 ± 1.4%). The ratio among these two analyses (named fold change) demonstrated viable hPLF with compromised cellular machinery along with the range of MeHg exposure. Subsequently, two distinct MeHg concentrations (0.3 and 3 µM) were chosen based on LC50 value (4.2 µM). hPLF exposed to these two MeHg concentrations showed an intracellular Hg accumulation as a linear-type saturation curve indicating that metal accumulated diffusively in the cells, typical for metal organic forms such as methyl. The levels of total GSH decreased 50% at exposure to 3 µM MeHg when compared to control. Finally, no alteration in the DNA integrity was observed at 0.3 µM MeHg exposure, but 3 µM MeHg caused significant damage. In conclusion, it was observed that MeHg exposure affected the general metabolism status of hPLF with no necessary decrease on the cell death. Additionally, although the oxidative imbalance in the hPLF was confirmed only at 3 µM MeHg through the increase of total GSH level and DNA damage, the lower concentration of MeHg used (0.3 µM) requires attention since the intracellular mercury accumulation may be toxic at chronic exposures.

Direct anterior composite veneers in vital and non-vital teeth: a retrospective clinical evaluation.

OBJECTIVES: This retrospective, longitudinal clinical study investigated the performance of direct veneers using different composites (microfilled×universal) in vital or non-vital anterior teeth. METHODS: Records from 86 patients were retrieved from a Dental School clinic, comprising 196 direct veneers to be evaluated. The FDI criteria were used to assess the clinical evaluation. The survival analysis was done using Kaplan-Meier method and Log-Rank test. The multivariate Cox regression with shared frailty was used to investigate the factors associated with failure. RESULTS: A total of 196 veneers were evaluated, with 39 failures. The mean time of service for the veneers was 3.5 years, with a general survival rate of 80.1%. In the qualitative evaluation of the restorations, microfilled composite showed slighty better esthetics. The annual failure rates (AFR) were 4.9% for veneers in vital teeth and 9.8% for non-vital teeth with statistical significance (p=0.009). For microfilled and universal veneers the respective AFRs were 6.0% and 6.2% (p>0.05). Veneers made in non-vital teeth had a higher risk of failure over time compared to those made in vital teeth (HR 2.78; 95% CI 1.02-7.56), but the type of material was not a significant factor (p=0.991). The main reason for failure was fracture of the veneer. CONCLUSION: Direct composite veneers showed a satisfactory clinical performance. Veneers performed in vital teeth showed a better performance than those placed in non-vital teeth. No difference in the survival rate for different composites was found, although microfilled composites showed a slightly better esthetic appearance. CLINICAL SIGNIFICANCE: Direct composite veneers show good results in esthetic dentistry nowadays. Composite veneers in vital teeth have a lower risk of failure than those in non-vital teeth.

The quantitative effect of diamond grit size on the subsurface damage induced in dental adjustment of porcelain surfaces.

Diamond burs with different grit sizes are often applied to adjust ceramic prostheses in restorative dentistry. However, the quantitative influence of diamond grit size on subsurface damage in adjusting ceramic prostheses is unknown. The aim of this study was to investigate and visualize the quantitative effect of diamond bur grit size on subsurface damage in dental adjusting of a feldspar prosthetic porcelain. Diamond burs with coarse (106-125 rm), medium (53-60 microm), and fine (10-20 microm) grit sizes were selected. Dental adjusting-induced subsurface damage was quantitatively investigated with the aid of finite element analysis (FEA) and scanning electron microscopy (SEM). Significant differences in subsurface damage depth were found among the coarse, medium, and fine diamond burs (ANOVA, p < 0.05). Coarse diamond burs induced approximately 6-8 times deeper subsurface damage than fine burs. Diamond grit size is confirmed to be a controlling factor in determining the degree of subsurface damage. Subsurface damage depths also significantly increased with removal rate (ANOVA, p< 0.05). The correlation of the SEM-measured subsurface damage depths and the diamond grit sizes supports the FEA predictions. From a practical standpoint, dental porcelains should be adjusted using smaller diamond grit sizes with lower removal rates to minimize subsurface damage.