Effects of curing modes on depth of cure and microtensile bond strength of bulk fill composites to dentin

Abstract Objectives To compare the microtensile bond strength (µTBS) and depth of cure (DOC) of bulk-fill composites cured by monowave (MW) and polywave (PW) LED units using different curing times. Methodology Three composites were tested: Tetric EvoCeram Bulk Fill (TBF), Filtek Bulk Fill (FBF), and Tetric EvoCeram (T; control). Flat dentin surfaces treated with adhesive (AdheSE Universal®, Ivoclar Vivadent) were bonded with 4 mm cylindrical samples of each bulk-fill composite material (n=6) and cured with monowave (Satelec) or polywave (Bluephase Style) curing units for 10 or 20 seconds. After 24 hours, teeth were sectioned into individual 0.9 mm2 beams and tested for µTBS. Failure modes were analysed. Moreover, the DOC scrape test (IOS 4090) was completed (n=5) following the same curing protocols. Two-way ANOVA (a=0.05) was performed, isolating light-curing units. Results For samples cured with the MW light-curing unit, no significant effects were observed in the µTBS results between any of the resin composite brands and the curing times. Conversely, when resins were cured with a PW light unit, a significant effect was observed for TBF resin. In general, bulk-fill composites presented greater DOC and longer curing time resulted in higher DOC for all composites. Conclusion The µTBS of the composites to dentin was not affected by the curing mode of the resins, except for TBF cured with PW light unit. Bulk-fill composites exhibit greater DOC than conventional resin-based composites.

Water interaction with dental luting cements by means of sorption and solubility / Interação da água com cimentos dentais de acordo com a sorção e solubilidade

Water contributes to the setting reaction of self-adhesive luting cements, however, it can also accelerate their degradation. Objectives: The aim of this study was to compare a self-adhesive resin luting cement to other resin-based and glass-ionomer luting materials with regards to water sorption (WS) and solubility (WSB). The tested null hypothesis was that there is no difference in respect to these properties among the materials. Material and methods: Eight specimens from each group (15 mm x 0.5 mm) were prepared from self-adhesive luting cements Biscem (BC) and RelyX Unicem (R), dual-cure cements Bifix (BF), Allcem (A) and Enforce (E), chemical-cure cements C&B (CB) and Cement Post (CP) and a glass-ionomer luting cement Meron C (M) as the control group. The dual-cure products were light-cured beneath an IPS Empress Esthetic ceramic disk (20 mm x 1.5 mm) and for the chemical reaction materials, a 15 min-interval was respected for removal from the mould. The WS and WSB were respectively calculated as (m2-m3/V) and (m1-m3/V). Mass values of m1, m2 and m3 were determined by cycles of desiccation, water-immersion and a new desiccation. For each property, the data was analyzed by one-criteria ANOVA and Tukey tests (p < 0.05). Results: The glass-ionomer cement presented the highest WS, followed by the self-adhesive luting cements. Other resin cements were less susceptible to WS. No materials differed from each other when the WSB was considered, except for the M, which presented the lowest WSB. Conclusions: Self-adhesive luting cements were more prone to WS since water is essential to their setting reaction. However, their WSB was similar to the other resin-based cements.

A água contribui para a reação de presa dos cimentos auto adesivos, entretanto pode acelerar a sua degradação. Objetivos: O objetivo deste estudo foi comparar cimentos auto adesivos a outros cimentos resinosos e material ionomérico em relação à sorção de água (WS) e solubilidade (WSB). A hipótese nula foi de que não há diferença em relação a essas propriedades entre os materiais. Material e métodos: Oito espécimes de cada grupo (15 mm x 0,5 mm) foram preparados dos cimentos auto adesivos Biscem (BC) e RelyX Unicem (R), cimentos duais Bifix (BF), Allcem (A) e Enforce (E), cimentos químicos C&B (CB) e Cement Post (CP) e um cimento ionomérico Meron C (M) como grupo controle. Os produtos duais foram fotoativados sob um disco cerâmico de IPS Empress Esthetic (20 mm x 1,5 mm) e para os materiais de reação química, um intervalo de 15 min foi respeitado para a remoção do molde. A WS e WSB foram respectivamente calculadas como (m2-m3/V) e (m1-m3/V). Valores de massa m1, m2 and m3 foram determinadas pelos ciclos de dessecação, imersão em água e nova dessecação. Para cada propriedade, os dados foram analisados pelos testes de ANOVA a um critério e Tukey (p < 0.05). Resultados: O cimento ionomérico apresentou a maior WS, seguido dos cimentos auto adesivos. Os demais cimentos resinosos foram menos suscetíveis a WS. Nenhum material diferiu do outro quanto a WSB foi considerada, exceto por M, que apresentou a menor WSB. Conclusões: Cimentos auto adesivos foram mais suscetíveis a WS, uma vez que a água é essencial para sua reação de presa. Entretanto, seu WSB foi similar aos demais cimentos resinosos.

Effect of an additional hydrophilic versus hydrophobic coat on the quality of dentinal sealing provided by two-step etchand-rinse adhesives

OBJECTIVE: To test the hypothesis that the quality of the dentinal sealing provided by two-step etch-and-rinse adhesives cannot be altered by the addition of an extra layer of the respective adhesive or the application of a more hydrophobic, non-solvated resin. MATERIAL AND METHODS: full-crown preparations were acid-etched with phosphoric acid for 15 s and bonded with Adper Single Bond (3M ESPE), Excite DSC (Ivoclar/Vivadent) or Prime & Bond NT (Dentsply). The adhesives were used according to the manufacturers' instructions (control groups) or after application to dentin they were a) covered with an extra coat of each respective system or b) coated with a non-solvated bonding agent (Adper Scotchbond Multi-Purpose Adhesive, 3M ESPE). Fluid flow rate was measured before and after dentin surfaces were acid-etched and bonded with adhesives. RESULTS: None of the adhesives or experimental treatments was capable to block completely the fluid transudation across the treated dentin. Application of an extra coat of the adhesive did not reduce the fluid flow rate of adhesive-bonded dentin (p>0.05). Conversely, the application of a more hydrophobic non-solvated resin resulted in significant reductions in the fluid flow rate (p<0.05) for all tested adhesives. CONCLUSIONS: The quality of the dentinal sealing provided by etch-and-rinse adhesives can be significantly improved by the application of a more hydrophobic, non-solvated bonding agent.

Avaliação da associação de clorexidina com etanol nadurabilidade da adesão à dentina / Evaluation of the adjunctive use of chlorhexidine and ethanol on the durability of resin dentin bonds

A degradação do adesivo e colágeno é considerada uma das principaiscausas de falhas nos processos adesivos à dentina. A completa infiltraçãode resinas hidrofóbas facilitada pelo etanol, associada à presença deinibidores de metaloproteinases presentes na dentina, poderia construir aunião ideal, resistente à hidrólise e atividades enzimáticas. Este estudoexaminou os benefícios do uso combinado de clorexidina como inibidor demetaloproteinases e etanol, na durabilidade de uniões resina-dentina.Foram utilizados 48 terceiros molares hígidos para obter superfícies planasde dentina que foram condicionadas com ácido fosfórico a 32% por 15segundos, lavadas por 30 segundos, e secas com papel absorvente.Imediatamente após, uma das seguintes soluções foi aplicada por 30segundos: água (A); etanol (E); solução aquosa de clorexidina a 1% (CA);solução alcoólica de clorexidina a 1% (CE). O excesso foi removido compapel absorvente e um dos adesivos, All Bond 3 (AB3) ou Excite (EX), foiaplicado à superfície sob agitação por 15 segundos, seguido por um jatode ar por igual tempo, e fotoativado por 20 segundos. Uma coroa deaproximadamente 4 mm foi construída incrementalmente em resinacomposta e os dentes foram armazenados por 24 horas em água destiladaà 370C. A seguir foram cortados em paralelogramos para o teste demicrotração. Um terço dos corpos de prova foi ensaiado imediatamente eos demais permaneceram armazenados por 6 ou 15 meses. Os efeitos dostratamentos e períodos de armazenagem foram analisados para cadaadesivo. Os resultados não demonstraram interação entre os fatores paraambos os adesivos.

AB3 foi significantemente afetado pela armazenagem,mas não pelos tratamentos. EX foi significantemente afetado pelotratamento, mas não pela armazenagem. Concluiu-se que o uso declorexidina/etanol não melhorou a estabilidade da união após 15 meses.AB3 quando tratado com A ou CA, e EX com todos os tratamentos nãoforam afetados pela armazenagem.

Both adhesive and collagen degradation have been regarded as majorcauses of resin-dentin bonds failures over time. Complete infiltration ofhydrophobic resins facilitated by ethanol, and the presence of MMPs’inhibitors within the hybrid layer would build the ideal interface, resistantto hydrolysis and enzymatic activities. This study examined the benefits ofthe adjunctive use of chlorhexidine and ethanol on the durability of resindentin bonds. Forty-eight flat dentin surfaces were etched (32%phosphoric acid), rinsed (30s) and blot-dried with absorbent paper. Thesurfaces were re-wetted with either water (Water); 1% chlorhexidinediacetate in water (CHX/Water); 100% ethanol (Ethanol); and 1%chlorhexidine diacetate in ethanol (CHX/Ethanol) solutions for 30s. Theywere then bonded with All Bond 3 (AB3, Bisco) or Excite (EX, Ivoclar-Vivadent) using a smooth, continuous rubbing application (15s), followedby 15s gentle air dry. The adhesives were light-cured (20s) and resinbuild-ups constructed incrementally for the microtensile method. Bondedbeams were obtained and tested after 24-hours, 6-months, and 15-months water storage at 370C. Effects of treatment and testing periodswere analyzed (ANOVA, Holm-Sidak, p<0.05) for each adhesive. Therewere no interactions between factors for both adhesives. AB3 wassignificantly affected by storage, but not by treatments. Excite wassignificantly affected by treatments, but not by storage. Adjunctive use ofethanol/chlorhexidine did not improve bond stability after 15 months. AB3treated either with ethanol or CHX/ethanol resulted in reduced bondstrengths after 15 months. AB3 treated with water or CHX/water and alltreatments for Excite were not affected by storage.

Resinas compostas posteriores: análise de longevidade e comportamento clínico / Posterior composite restorations: analysis of longevity and clinical performance

A proposta deste estudo foi determinar como as resinas compostas inseridas em dentes posteriores têm se comportado clinicamente. A influência de fatores como higiene oral e risco à cárie, tamanho e localização da cavidade a ser restaurada, características físico-químicas das resinas compostas e a técnica operatória foram analisadas. As principais causas de falhas que determinam a substituição da restauração são a infiltração marginal e o desgaste. os critérios e o bom senso clínico para indicar uma restauração de resina composta em dentes posteriores são de importância fundamental para que elas tenham razoável longevidade. A otimização de resultados a longo prazo depende diretamente da análise crítica do profisional frente à cada situação clínica e dos cuidados com a técnica restauradora que ele emprega