Emulating In vitro the Clinical Deterioration of Restored Anterior Teeth

Objectives: Recent clinical data indicate that anterior composite restorations in patients with severe tooth wear show a pattern of deterioration of the incisal interface after 4-years. This study aimed to emulate in vitro the deterioration observed for those anterior composite restorations and compare two chewing simulators in their ability to generate aging effects compatible with clinical findings.
Methods: Bovine incisors prepared to simulate severely worn teeth were restored using the same materials and techniques used in vivo: Clearfil AP-X for palatal and IPS Empress Direct for buccal surfaces. The specimens were assigned to two chewing simulators (n=15): mechanical cyclic loading (Biocycle-V2) or mechanical loading + wear (Rub&Roll). 960,000 aging cycles were performed (~4-years of clinical service). Restorations were assessed under magnification (10×) and rated according to five FDI criteria for evaluating restorations. Findings were compared to clinical data of similar restorations placed in 10 patients with severe tooth wear (follow-up: 4-years). Differences between devices for each FDI criterion were analyzed using Fisher’s exact test (p<0.05).
Results: In Biocycle-V2, the aging effects were limited to wear at the contact area of the load piston (contact damage), whereas Rub&Roll generated incisal wear, ditching, and interface fracture chipping resembling the restorations evaluated clinically (chipping fracture, ditching and surface roughness). No significant difference was observed between the devices for marginal adaptation (p=0.47), whereas higher FDI scores were generated by Rub&Roll considering fracture (p=0.01) and three esthetic criteria (p≤0.037).
Conclusions: This study was able to emulate the clinical deterioration observed at the incisal edges of anterior composite restorations by using a laboratorial aging method that combined mechanical cycling loading and wear (Rub&Roll). The method may contribute to translational research by allowing in vitro simulation of clinical aging of dental restorations.