Effect of prolonged water storage and repeated thermocycling on the reinforcing ability of refrigerated Amalgambond Plus/High Performance Additive in third molars with large mesio-occlusodistal amalgam restorations

Abstract

Objective: This in vitro investigation examined what effect prolonged water immersion and repeated thermocycling had on the fracture strength of extracted third molars restored with refrigerated Amalgambond Plus with High Performance Additive (AB+/HPA) and Tytin amalgam. Materials and Methods: Mesio-occlusodistal (MOD) channels were prepared in one member from each of 19 contralateral pairs. After restoration, specimens were stored in water for 6 months, with thermocycling repeated every 2 months. Specimens were fractured in a universal testing machine, and the data were analyzed. Secondary effects of tooth location and tooth size were also examined. Results: Fracture strengths of prepared/restored teeth were not statistically different from those of intact contralateral pairs (p > 0.05). Maxillary teeth had lower fracture strengths than mandibular teeth, and tooth size had no effect on fracture strength. Conclusions: Extracted molars with large MOD amalgam restorations bonded with refrigerated AB+/HPA had fracture strengths equivalent to those of intact contralateral pairs after 6 months of water storage and repeated thermocycling.