Repair bond strength of dual-cured resin composite core buildup materials

Abstract

The reparability of dual-cured resin composite core buildup materials using a light-cured one following one week or three months storage, prior to repair was evaluated. Two different dual-cured resin composites; Cosmecore™ DC automix and Clearfil™ DC automix core buildup materials and a light-cured nanofilled resin composite; Filtek™ Z350 XT were used. Substrate specimens were prepared (n = 12/each substrate material) and stored in artificial saliva at 37 °C either for one week or three months. Afterward, all specimens were ground flat, etched using Scotchbond™ phosphoric acid etchant and received Single Bond Universal adhesive system according to the manufacturers’ instructions. The light-cured nanofilled resin composite (Filtek™ Z350 XT) was used as a repair material buildup. To determine the cohesive strength of each solid substrate material, additional specimens from each core material (n = 12) were prepared and stored for the same periods. Five sticks (0.8 ± 0.01 mm2) were obtained from each specimen (30 sticks/group) for microtensile bond strength (μTBS) testing. Modes of failure were also determined. Two-way ANOVA revealed a significant effect for the core materials but not for the storage periods or their interaction. After one week, dual-cured resin composite core buildup materials (Cosmecore™ DC and Clearfil™ DC) achieved significantly higher repair μTBS than the light-cured nanofilled resin composite (Filtek™ Z350 XT). However, Clearfil™ DC revealed the highest value, then Cosmecore™ DC and Filtek™ Z350 XT, following storage for 3-month. Repair strength values recovered 64–86% of the cohesive strengths of solid substrate materials. The predominant mode of failure was the mixed type. Dual-cured resin composite core buildup materials revealed acceptable repair bond strength values even after 3-month storage.

Shear Bond Strength for Immediate and Delayed Repair of Composite With Microhybrid and Nanohybrid Resins Using Different Bonding Agents

“…This was in agreement with Deeb et al (23) and El Askary et al (24) who found that immediately repaired composite has bond strength greater than the delayed one.…”

To evaluate and compare the effect of different light-curing modes and different liners on cuspal deflection in premolar teeth restored with bulk filled or incrementally filled composite measured at different time intervals

“…Intergroup comparison showed that groups restored with sonic fill composite (Group A) had significantly lower cuspal deflection as compared to groups restored with Filtek Z350 XT composite (Group B). According to the literature, increased filler content (83.5 wt%)[ 7 ] and decreased percentage volumetric shrinkage of Sonic fill composite (1.6%)[ 8 ] might have resulted in lower cuspal deflection as compared to Filtek Z350 XT composite which have filler content of 78.5 wt%[ 9 ] and percentage volumetric shrinkage of 1.97%. [ 10 ]…”

Critérios clínicos para decisão entre substituição ou reparo de restaurações em resina composta – revisão de literatura

“…31 O critério fratura (do dente e/ou da restauração) também foi citado como prevalente em 33,3% dos artigos avaliados. 6,19,22,24,[32][33][34] De acordo com Demarco et al, 19 o motivo de a fratura ser apresentada como uma das principais razões para falha de restaurações em resina composta pode ser justificado pelo fato de que o material utilizado apresenta um maior módulo de elasticidade e dureza em relação ao dente. Além disso, há a influência do tamanho cavitário (desgaste dental) nessas falhas, sendo que dentes com preparos cavitários maiores apresentam maiores chances de desenvolver fratura ao longo do tempo.…”