A Combined Amalgam-Composite Filling Technique to Resist Cuspal Fracture

This study was carried out to study a restorative technique of 2 mm thickness of composite resin filling material that bonded, by adhesive (4-META), to MOD cavities (Mesial, Occlusal and Distal surfaces of a tooth) partially filled with amalgam filling materials in upper premolars on the fracture resistance when compared to a sound tooth. Forty freshly sound extracted upper premolars were divided into four groups: the first group of ten sound premolars is subjected to fracture resistance test, the second group of ten premolars with a MOD of half intercuspal distance cavities, which was prepared with long bevel at the cavosurface angle and the teeth were filled with composite resin following incremental technique. The third group of ten teeth were prepared with a box form and butt joint of the same MOD cavities dimension and filled with non-gamma II amalgam. The fourth group of ten premolars with the same MOD cavities dimension are filled with amalgam, a 2 mm thickness of amalgam was removed of the occlusal surface after 24 hours, extended proximally mesially and distally, etch of the exposed enamel, dentin and amalgam was performed, and 4-META adhesive was applied to amalgam and exposed dentin and enamel followed by posterior composite bonded to tooth and amalgam, and cured with light for 40 seconds. The teeth of all groups were tested for fracture resistance. The group I showed the highest resistance to fracture followed by group IV followed by group II and lastly, group III. This study concluded that the use of combined bonded amalgam-composite and tooth structure provided the best technique for filling than cavity only filled with composite or amalgam.