X-Ray Microtomography Analysis of Gaps and Voids in the Restoration of Non-Carious Cervical Lesions with Different Composite Resins

Context (Background): Resin composites are the most widely used material for restoring cervical defects. However, the high failure rate of these restorations is still a concern. Aims: The aim of this in vitro study was to evaluate, using microtomography (?CT), the interfacial gap and voids formation in Class V cavities in premolars restored with materials with lower polymerization shrinkage combined with different restorative techniques. Settings and Design: Cervical defects were created in 30 intact premolar and were randomly distributed to be restored by one of the following techniques (n = 6): Composite resin with two increments (CR), organic modified polymer (ORMOCER) with single (OR1) or two increments (OR2, or low viscosity bulk?fill composite resin with single (BF1) or two increments (BF2). Methods and Material: Each tooth was scanned before filling to determine the volume of interest (VOI) to be applied in the second ?CT after restoration and to control the cavity volume among the groups. In the ?CT after filling, the volume of interfacial gaps and voids was calculated for each group. Statistical Analysis: The groups were compared using one?way and Tukey HSD post hoc test (? = 0.05). Results: It was possible to identify higher gap formation in the OR1 group and higher void formation in CR group (P < 0.05). OR2 group showed better results than the group with one increment. BF2 showed the best filling capacity. Conclusions: It was possible to conclude that the material and the number of increments directly influenced the internal adaptation and voids formation of Class V restorations.

Do dual-cure bulk-fill resin composites reduce gaps and improve depth of cure

Abstract This in vitro study aimed to evaluate the gaps length and depth of cure of dual-cure bulk-fill resin composites inserted in box-shaped preparations. Box-shaped preparations (4 mm deep) were made in fifteen human third-molars and divided into three groups according to the resin composites (n=5): Dual-cure bulk-fill BulkEZ (BEZ); Dual-cure bulk-fill HyperFIL (HF); and Tetric Evoceram Bulk-fill (TETRIC), as control. Gaps length (%) was evaluated in tooth-restoration interface with micro-computed tomography (µCT). The restorations were sectioned, and the degree of conversion (DC) and Knoop microhardness were evaluated at five depths (0.3, 1, 2, 3, and 4 mm). Microhardness data were statistically evaluated using absolute values (KHN) and relative values (microhardness percentages in relation to top). Gaps length (%) increased in the following order: BEZ=TETRIC<HF. The microhardness percentages in relation to top significantly decreased from 2 mm for TETRIC and 3 mm for HF. BEZ had constant microhardness and DC at all depths, while HF and TETRIC presented a significant decrease on DC at 4 mm. Dual-cure bulk-fill composites did not reduce gaps compared to light-cure bulk-fill, but they can improve depth of cure of bulk-filled restorations.

Resumo O objetivo neste estudo in vitro foi mensurar as fendas e a profundidade de polimerização de compósitos resinosos bulk-fill duais inseridos em preparos em forma de caixa. Os preparos em forma de caixa (4 mm de profundidade) foram realizados em quinze terceiros molares e separados em 3 grupos, de acordo com o compósito resinoso (n = 5): Bulk-fill dual BulkEZ (BEZ); Bulk-fill dual HyperFIL (HF); Tetric Evoceram Bulk-fill (TETRIC). O comprimento das fendas (%) foi avaliado na interface dente-restauração por meio de micro-tomografia computadorizada (µCT). As restaurações foram seccionadas e o grau de conversão (GC) e microdureza Knoop foram avaliados em cinco profundidades (0,3, 1, 2, 3 e 4 mm). Os dados de microdureza foram avaliados estatisticamente por meio de valores absolutos e relativos (porcentagens de microdureza em relação ao topo). O comprimento das fendas (%) aumentou na seguinte ordem: BEZ = TETRIC <HF. O percentual de microdureza em relação ao topo diminuiu significativamente a partir de 2 mm para TETRIC e 3 mm para HF. BEZ apresentou percentuais de microdureza e de GC constantes em todas as profundidades, enquanto HF e TETRIC apresentaram decréscimo significativo no GC em 4 mm. Os compósitos resinosos bulk-fill duais não reduziram as fendas formadas quando comparados a um compósito bulk-fill fotopolimerizável; entretanto, os mesmos podem melhorar a profundidade de polimerização em restaurações de incremento único.

The Use of Micro-Computed Tomography for Evaluation of Internal Adaptation of Dental Restorative Materials in Primary Molars: An In-Vitro Study

Aim: To evaluate the internal adaptation of some dental adhesive restorative material (Nano-composite resin /Biodentine,Nanocomposite resin / Nano- resin-modified glass ionomer and Nano-composite resin) to the primary dentinal surface usingmicro-computed tomography (Micro-CT) Materials and methods: Forty-five extracted primary molars, due to caries ororthodontic reasons, were collected provided that it has an intact buccal/ lingual surface(s) and one half to two-thirds ofroot length. The selected teeth were disinfected and stored in normal saline at room temperature. The teeth were randomlyassigned to one of the three experimental restorative groups according to the restoration type (15 per group): group A:Nanocomposite resin / Biodentine, group B: Nanocomposite resin / Nano-resin-modified glass ionomer and group C:restored totally with Nanocomposite resin. A high- resolution desktop micro-CT (Model 1172, Skyscan, Belgium) was usedto image the samples. Results: The mean rank of volumetric dimension values of the total gap at the restorative material –dentine interface demonstrated significant difference among the three groups (P= 0.003). Moreover, there was a significantdifference in the mean rank of the ratio of total gap volume/cavity volume among the three restorative groups (P=0.015).The data demonstrate that group A showed the lowest in total gap volume and mean ratio of total gap volume /cavity volumewhile group C recorded the highest value. Conclusion: Biodentine exhibited a higher internal adaptation to a dentinalsurface which is comparable to Nano resin-modified glass ionomer. The study results potentiate the importance of usingBiodentine liners under Nano-composite (sandwich technique) in terms of excellent internal adaptation, in addition to itshigh biocompatibility and easy handling as well.

Effect of different impression methods and ceramic materials on adaptation of inlays / Efeito de diferentes métodos de moldagem e materiais cerâmicos na adaptação de inlays

Objective: The aim of this study was to evaluate the internal and marginal adaptation of inlays fabricated from different types of impressions (conventional and digital) and different ceramics (feldspathic and lithium disilicate). Material and Methods: Forty premolars were prepared for all-ceramic inlay restoration and assigned to 4 groups (n=10), according to the impression method (conventional with addition silicone and digital impression) and ceramic type (lithium disilicate and feldspathic ceramic blocks). For each type of impression, 10 inlays were milled from lithium disilicate blocks and the other 10 from feldspathic ceramic blocks in a CAD-CAM facility. The internal adaptation was analyzed by the replica technique. The marginal fit was analyzed under a stereo microscope by directly measuring the gap formed between the inlay and the tooth in the proximal and occlusal regions. Results: The marginal or internal adaptations were not affected by type of impression (conventional = digital impression), irrespective of the ceramic type. Only the internal adaptation was affected by the material type, i.e., feldspathic ceramic had lower values than lithium dissilicate ceramic, when considering the digital impression. Conclusion: The conventional and digital impressions promoted similar marginal and internal adaptation for feldspathic and disilicate ceramic inlays. For the digital impression the feldspathic inlays showed better internal adaptation than lithium dissilicate inlays. (AU)

Objetivo: O objetivo deste estudo foi avaliar a adaptação interna e marginal de inlays confeccionadas a partir de diferentes tipos de moldagens (convencional e digital) e diferentes materiais cerâmicos (feldspática e dissilicato de lítio). Materiais e Métodos: Quarenta pré-molares foram preparados para inlay totalmente cerâmica e distribuídos em 4 grupos (n = 10) segundo o método de moldagem (convencional com silicone de adição e moldagem digital) e tipo cerâmica (dissilicato de lítio e blocos de cerâmica feldspática). Para cada tipo de moldagem, 10 inlays foram confeccionadas a partir de pastilhas de dissilicato de lítio e as outras 10 de blocos de cerâmica feldspática, por meio do sistema CAD-CAM. A adaptação interna foi analisada pela técnica da réplica. O ajuste marginal foi analisado com estéreo microscópio medindo diretamente o espaço entre a inlay e o dente nas regiões proximal e oclusal. Resultados: As adaptações marginais e internas não foram afetadas pelo tipo de moldagem (convencional = impressão digital), independentemente do tipo de cerâmica. Somente a adaptação interna foi afetada pelo material, sendo que a cerâmica feldspática apresentou menores valores que a cerâmica de dissilicato, considerando a moldagem digital. Conclusão: As moldagens convencional e digital promoveram adaptação marginal e interna semelhante de inlays de cerâmica feldspática e dissilicato testadas. Para moldagem digital, a cerâmica feldspática mostrou melhor adaptação interna do que a dissilicato de lítio (AU)

Effect of Adhesive Overflow Grooves on the Adaptation of a Molar Zirconia Full Crown / 中国医科大学学报

Objective To study the effect of adhesive overflow grooves on the marginal and internal adaptation of a molar zirconia full crown.Methods A three-dimensional model of a mandibular first molar was established.Four crown preparations (A-D) were designed:a was a conventional full crown design,and B,C,and D included 1,2,and 4 adhesive overflow grooves,respectively,designed on the basis of A.Five resin preparations were created for each group using three-dimensional (3D) printing.According to the a design data,20 CAD/ CAM zirconia crowns were prepared and randomly divided into four groups.The tooth,preparations,and crowns underwent 3D scanning for 3D deviation analysis and 3D wall thickness analysis.The gap between the crown and the preparation was replicated with silicone rubber,and then observed with a metallographic microscope and measured.Data were statistically analyzed with SPSS 17.0.Results Among the groups,marginal and internal clearance was A＞B＞C＞D.The comparison between every two groups was statistically different (P ＜ 0.05).Conclusion Increases in the number of overflow grooves result in significant increases in the marginal adaptation and internal adaptation of a full crown.

Micro-CT evaluation of internal adaptation in resin fillings with different dentin adhesives

OBJECTIVES: The purpose of present study was to evaluate the internal adaptation of composite restorations using different adhesive systems. MATERIALS AND METHODS: Typical class I cavities were prepared in 32 human third molars. The teeth were divided into the following four groups: 3-step etch-and-rinse, 2-step etch-and-rinse, 2-step self-etch and 1-step self-etch system were used. After the dentin adhesives were applied, composite resins were filled and light-cured in two layers. Then, silver nitrate solution was infiltrated, and all of the samples were scanned by micro-CT before and after thermo-mechanical load cycling. For each image, the length to which silver nitrate infiltrated, as a percentage of the whole pulpal floor length, was calculated (%SP). To evaluate the internal adaptation using conventional method, the samples were cut into 3 pieces by two sectioning at an interval of 1 mm in the middle of the cavity and they were dyed with Rhodamine-B. The cross sections of the specimens were examined by stereomicroscope. The lengths of the parts where actual leakage was shown were measured and calculated as a percentage of real leakage (%RP). The values for %SP and %RP were compared. RESULTS: After thermo-mechanical loading, all specimens showed significantly increased %SP compared to before thermo-mechanical loading and 1-step self-etch system had the highest %SP (p < 0.05). There was a tendency for %SP and %RP to show similar microleakage percentage depending on its sectioning. CONCLUSIONS: After thermo-mechanical load cycling, there were differences in internal adaptation among the groups using different adhesive systems.

Evaluation of internal adaptation of dental adhesive restorations using micro-CT

OBJECTIVES: The internal adaptation of composite restorations with or without resin modified glass ionomer cement (RMGIC) was analyzed non-destructively using Microcomputed tomography (micro-CT). MATERIALS AND METHODS: Thirty intact human teeth were used. The specimens were divided into 3 groups. In the control group, the cavities were etched with 10% phosphoric acid for 15 sec. Composite resin was filled into the cavity without adhesive. In group 1, light cured glass ionomer cement (GIC, Fuji II LC, GC) was applied as a base. The cavities were then etched, bonded, light cured and filled with composites. In group 2, the cavities were then etched, bonded, light cured and filled with composites without base application. They were immersed in a 25% silver nitrate solution. Micro-CT was performed before and after mechanical loading. One-way ANOVA with Duncan analysis was used to compare the internal adaptation between the groups before or after loading. A paired t-test was used to compare internal adaptation before and after mechanical loading. All statistical inferences were made within the 95% confidence interval. RESULTS: The silver nitrate solution successfully penetrated into the dentinal tubules from the pulp spaces, and infiltrated into the gap between restoration and pulpal floor. Group 2 showed a lower adaptation than the control group and group 1 (p < 0.05). There was no significant difference between the control group and group 1. For all groups, there was a significant difference between before and after mechanical loading (p < 0.05). CONCLUSIONS: The internal adaptation before and after loading was better when composites were bonded to tooth using adhesive than composites based with RMGIC.