In vivo evaluation of different techniques for establishment of proximal contacts in posterior resin composite restorations

Aim: To evaluate the re-establishment of proximal contacts on class II resin composite restorations by means of 4 different in vivo techniques. Methods: Restorations were divided into 4 groups (N=10): Group 1 (preformed metallic matrix + wooden wedges + separating ring); Group 2 (preformed metallic matrix + elastic interdental wedges+ separating ring); Group 3 (preformed metallic matrix + wooden wedges + translucent contact spatula); Group 4 (preformed metallic matrix + wooden wedges + resin inserts). Initially, two previously calibrated examiners conducted training on models representing three different proximal contact situations: tight (T); satisfactory (S) and unacceptable (U). Two evaluations were accomplished: immediately and 30 days after the restorative procedures. Fisher’s exact test was used to verify differences among the techniques for establishment of proximal contacts in posterior resin composite restorations. Results: There was no statistically significant differences (p>0.05) among the 4 groups. Conclusions: All techniques produced satisfactory proximal contacts. Different restorative techniques for class II resin composite cavity preparations enabled satisfactory proximal contacts.

Microleakage in class II composite resin restorations: total bonding and open sandwich technique.

PURPOSE: The objective of this in vitro study was to evaluate gingival microleakage in Class II total bond resin restorations in comparison to open sandwich technique restorations using different materials. MATERIALS AND METHODS: Forty-eight human molar teeth were disinfected and stored in a 0.9% saline solution. In each tooth, two standardized Class II cavities (3 mm x 6 mm x 2 mm) were prepared with the gingival cavosurface margins located 1 mm below the cementoenamel junction. The teeth were divided into 4 equally sized groups (n = 12), and the proximal boxes were treated as follows: in Group 1, no base material was used and the cavity was restored using SyntacSprint (SS) and Tetric Ceram (TC); in Groups 2, 3, and 4 the gingival portion of the cavity was restored with different base materials (Group 2, Dyract; Group 3, Vitremer; Group 4, Chelon-fil) prior to the placement of the composite resin. After a storage time of 7 days, the restorations were finished and polished. Then, specimens were submitted to thermocycling (500 cycles, 5 degrees C to 55 degrees C, 15 s dwell time) and immersed in a 0.5% methylene blue solution for 24 h. After washing, they were sectioned in a mesio-distal direction. Each restoration was evaluated under a stereomicroscope at 20x by 2 examiners and scored on a 0 to 3 scale according to the marginal leakage. Kappa statistics were used to evaluate the agreement between the examiners. Given the ordinal nature of the scoring system, data were submitted to a nonparametric repeated measures ANOVA. The results were confirmed with a parametric repeated measures ANOVA. RESULTS: Significant differences (p < 0.001) among the four groups with respect to dye penetration were detected, with the association Vitremer/Tetric showing the best results. CONCLUSION: The use of Vitremer in the open sandwich technique presents the lowest degree of microleakage among the treatments considered in this study.

Espectro de umidade da superfície dentinária para três sistemas adesivos com diferentes solventes / Moisture spectrum of demineralized dentin for three different solvent-based adhesive system

O objetivo deste estudo foi verificar o comportamento de adesivos com diferentes solventes: Single Bond (SB), a base de águaálcool; One-Step (OS), a base de acetona e Syntac Single Component (SC) a base de água sob diferentes condiçöes de umidade da dentina. Noventa terceiros molares hígidos tiveram a superfície oclusal desgastada por expor a dentina. Uma área de dentina, com cerca de 52mm, foi delimitada em cada espécime com tira adesiva; as superfícies foram condicionados com os respectivos ácidos (15s) e secas com jatos de ar (30s). O adesivo foi, entäo, aplicado de acordo com a recomendaçäo do fabricante em superfície seca (Oµl) ou umedecida com água (1,5; 2,5; 3,5; 4,0; 4,5µl), seguido de fotoativaçäo com intensidade luminosa de 600m/Wcm² (VIP, Bispo). Após a inserçäo e ativaçäo de 3 incrementos da resina Z-250 (ñ 1,5 mm, 30s cada), os espécimes foram armazenados em água destilada a 37ºC por 24 h. Cortes longitudinais paralelos e perpendiculares à interface de uniäo foram realizados de moda a se obter corpos-de-prova com seçäo transversal de 0,8mm², os quais foram testados sob traçäo a velocidade de 0,5 mm/min. Os dados submetidos à análise de variância e análise de regressäo e permitem concluir que o sistema SB e o SC (ambos contendo água) apresentam melhor desempenho em substrato mais seco, porém as médias do SB säo superiores nestas condiçöes. O sistema OS (a base de acetona) apresentou melhor desempenho em campo mais úmido