Abstract

The history of pins is 170 years back, with only 50 papers for 70 years, due to the difficulties in the research in this field. The aim of the present study is to test the role of pins in the fracture resistance of class II restorations with amalgam and resin material. Materials and method 50 matured sound molars are placed in groups: upper-20, lower-30, and after fillings: amalgam-24 and resin material-26 with and without pins. Cavities class II are prepared with absence of approximal wall, one cusp and parts from the buccal and lingual walls. The 4 sizes of the cavities are in respect with the sizes of the clinical crowns and with close volumes. For all restorations Prime bond NT was used. Termocycling: 30 days in 30ºС, 100% humidity, 60 days in 100% humidity and 100 dry cycles, 20 seconds each in the following order - 45ºС±3ºС, room temperature, 5ºС, room temperature, two series 50 each with two days between in Cultura incubator of Viva Dent 55ºС and ice. Machine for vertical load testing ZD 10/90 was used: load was in Newtons (N), from 20 N to 1275 N, speed 0.5 mm/min, displacement from 0.1 to 1.2 mm. Type of the observed fractures: adhesive, cohesive in dentine and in resin material, mixed. Results: The findings are equally not related to upper and lower teeth and to the small variations in the sizes of the cavities. Treatment of class II cavities with pins and dental amalgam is increasing the fracture resistance of the restorations (2293-3167 N). Lower resistance is observed when resin materials are used without pins (1599-2592 N). Conclusion: The treatment planning of pins in class II cavities is recommended to be related to the type of occlusion and to the nature of the opposite teeth (enamel, ceramics, etc.).

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