Morphological Assessment of Aged Adhesive Interfaces

Objective: “Study the past if you would define the future” (Confucius).  The aim of this study was to evaluate the ultra-morphology features of adhesive joints in aged retrieved restored teeth and non-aged restored sound teeth.

Method: Anterior teeth with aged RBC restorations (+10 years of service) indicated for extraction due to periodontal or prosthetic needs were collected and stored in fixative (48h).  No chart review was gathered regarding the material used or the operator experience. Teeth were then prepared for FE-SEM evaluation. Briefly, they were sectioned into slabs of ±1 mm (Isomet 1000, Buehler) to expose enamel-resin-dentin interfaces and one central slab was selected, dehydrated, placed in molds and embedded with epoxy resin.  Samples were then polished with 320, 600, 1200 and 2400-grit sandblast paper, then demineralized with 6NHCl for 30s and deproteinized with 2.5% NaOCl for 10 min. As a non-aged group, sound molars were restored and similarly processed for SEM.

Result: Ultra-morphological evaluation of the adhesive joint in aged adhesive interfaces depicted areas of non-degraded as well as gradual dissolution of the adhesive with partial disruption of the joint in several locations along the interface. The adhesive layer and the adjacent restorative resin presented porosities.  Resin tags had areas of polymer breakdown filled with either “crystal” or globular shape entities. Adhesive joints and resin tags features in non-aged sound teeth were homogeneous then in the aged retrieved restored teeth.

Conclusion: The findings suggest that there are ultra-morphological features changes in the aged adhesive joints if compared to non-aged. These features were indicative on how the joints degrade over time, which can be used as a knowledge basis to improve materials and techniques.