Study on the quality of adhesion in the case of 5th class cavities

Abstract

Objective. The aim of the present study is to evaluate the adhesion of the diacrylic composite resins to cementum, with or without an intermediate layer of flowable composite. Materials and method. Standardized class V cavities were made on the vestibular surfaces of 24 maxillary third molars. The cavities were filled with microhybrid (Filtek Z250 – 3M/ESPE), respectively nanohybrid composites (FIltek Z550 – 3M/ESPE), half of these also having an intermediate layer of flowable composite (Gradia Direct LoFlo - GC). All of the specimens were subjected to a thermocycling process (300 cycles in water of 5°/55°). After the isolation of the teeth with nail polish, they were introduced into 1% methylene blue for 24 hours. Subsequently, they were embedded in an epoxy resin (EpoThinTM2 – Buehler), polished and sectioned mesio-distally with Beta Grinder/Polisher – Buehler. The sections were selected where the greatest degree of methylene blue penetration was detected to be analyzed by optical polarized light microscopy (Axio Imager A1m – Zeiss). Conclusion. The composite fillings allow the microinfiltration of the cementum and dentine, leading in time to the possibility of direct restoration failure. Also, the existence of an intermediate layer of flowable composite does not improve adhesion.

Keywords

• diacrylic composite resins
• adhesion
• dentine
• cement
• intermediate layer
• microhybrid
• nanohybrid