Light curing tip contamination and surface hardness of resin composite
Buckley N, Ray N, Burke FM
Objectives: This study aimed to measure the effect on Vickers Hardness Number (VHN) of a resin composite (RC) material by curing through a pre-cured RC mask as a model of curing tip contamination. The Null hypothesis is that neither top nor bottom hardness numbers of RC materials are affected by curing through a mask of the corresponding material for the geometry specified and within the parameters of the investigation.
METHOD:
Preparation of masks: A simulated light curing tip mask was prepared for each of 2 commercially available RC tooth restorative materials (Ceramx Duo (CD), Esthetx HD (EHD), Dentsply Detrey GmbH), by filling a polyamide washer (1.6 mm x 8 mm; Fabory) with each material and light-curing from the top and bottom surface with a commercial LCU at full intensity. Both masks were allowed to mature for 7 days at room temperature.
Preparation of specimens:
Disc specimens for both materials, were prepared by filling similar washers and exposure on one surface for 30 secs. One half of the specimens for each material were exposed through an empty washer spacer. The remainder were covered by the relevant mask before exposure. Top & bottom VHN readings were recorded after storage for 1 week (dry).