Avaliação das propriedades mecânicas de resinas compostas fotoativáveis submetidas a ativação complementar / Evaluation of the mechanical properties of light-cure composite resins submitted to post-cure

Objective: This study evaluated the flexural strength and Vickers hardness of a direct restorative composite resin (Filtek P-60TM), submitted or not to the post-cure, and a laboratory composite resin (ArtglassTM). Methods: The flexural strength tests followed the ISO 4049:1988 regulations, and the Vickers microhardness tests the ASTM E-384:1999 regulations. The Filtek P-60TM com-posite resin was cure activated as follows: Group I - conventional light cure; Group II - conventional li-ght cure followed by post-cure with dry heat; Group III - conventional light cure followed by post-cure in a stroboscopic light unit; Group IV - ArtglassTM composite resin was light cured in a stroboscopic unit. After cure activation procedures, the samples were kept in deionized water at 37 ± 1 oC for 24h and protected from light. Results were submitted to Anova and Duncan?s test and revealed an increase in flexural strength and Vickers microhardness test after Filtek P-60TM post-cure. Results and Conclusion: It is possible to conclude that the Vickers microhardness values for Filtek P-60TM samples were superior to the ArtglassTM composite resin values; and that the flexural resistance values for Filtek P-60TM submitted to post-cure were superior to the ArtglassTM resin values.

Cariostatic effect of fluoride-containing restorative materials associated with fluoride gels on root dentin

Secondary caries is still the main cause of restoration replacement, especially on the root surface OBJECTIVE: This in vitro study evaluated the cariostatic effects of fluoride-containing restorative materials associated with fluoride gels, on root dentin. MATERIALS AND METHODS: A randomized complete block design was used to test the effects of the restorative systems, fluoride regimes and the interactions among them at different distances from restoration margins. Standardized cavities were prepared on 240 bovine root specimens and randomly assigned to 15 groups of treatments (n=16). Cavities were filled with the following restorative materials: Ketac-Fil (3M-ESPE); Vitremer (3M-ESPE); Dyract/Prime & Bond NT (Dentsply); Charisma/Gluma One Bond (Heraeus Kulzer) and the control, Z250/Single Bond (3M-ESPE). The specimens were subjected to a pH-cycling model designed to simulate high-caries activity. During the cycles, 1.23 percent acidulated phosphate fluoride, 2.0 percent neutral sodium fluoride or deionized/distilled water (control) was applied to the specimens for 4 min. The surface Knoop microhardness test was performed before (KHNi) and after (KHNf) the pH cycles at 100, 200 and 300 mm from the margins. Dentin microhardness loss was represented by the difference in initial and final values (KHNi - KHNf). Data were analyzed by Friedman's and Wilcoxon's tests, ANOVA and Tukey's test (α=5 percent). RESULTS: The interaction of restorative systems and topical treatments was not significant (p=0.102). Dentin microhardness loss was lowest closer to the restoration. Ketac-fil presented the highest cariostatic effect. Vitremer presented a moderate effect, while Dyract and Charisma did not differ from the control, Z250. The effects of neutral and acidulated fluoride gels were similar to each other and higher than the control. CONCLUSION: Conventional and resin-modified glass ionomer cements as well as neutral and acidulated fluoride gels inhibit the progression of artificial caries adjacent to restorations. The associated effect of fluoride-containing restorative materials and gels could not be demonstrated.

Effectiveness and efficiency of chemomechanical carious dentin removal

O objetivo deste estudo in vitro foi determinar o tempo gasto para a remoção de dentina cariada (eficiência) e a microdureza Knoop (KHN) da dentina remanescente (eficiência), usando o método químico-mecânico (Carisolv) ou escavação manual. Trinta molares humanos foram seccionados através da lesão de cárie oclusal, produzindo duas metades iguais. Cada metade foi escavada, aleatoriamente, utilizando um escavador manual ou o kit Carisolv gel, seguindo as instruções do fabricante. O tempo gasto para a remoção da dentina cariada foi registrado. As hemi-secções foram incluídas em resina, planificadas e polidas. KHN da dentina remanescente foi determinada nas distâncias de 100, 200, 300, 400 e 500 mm, a partir do assoalho cavitário. Os dados foram analisados pelos testes de Wilcoxon (a=0,01), ANOVA e t de Student (a=0,05). O tempo gasto na escavação químico-mecânica foi significativamente maior que na escavação manual. As médias e os desvios-padrão de KHN a 100, 200, 300, 400, 500 mm foram, respectivamente, para o método químico-mecânico: 15,6 (±4,96), 18,0 (±6,22), 21,3 (±9,30), 24,3 (±9,25), 28,5 (±11,80); e para a escavação manual: 21,2 (±10,26); 23,4 (±9,49); 28,2 (±11,62); 31,0 (±12,17); 34,3 (±11,95). Concluiu-se que a escavação manual apresentou maior efetividade e eficiência que a escavação assistida pelo Carisolv.