Histological evaluation of the human pulp response to cavity preparation

Objectives: The aim of this study was to histologically evaluate of the effect of two different cavity preparation techniques on human pulp response. Methods: Class V buccal preparations were randomly made in 24 healthy premolars scheduled for extraction for orthodontic reasons (n=28). Group 1 (n=12) cavity preparation with high speed turbine and conventional diamond bur, Group 2 (n=12) cavity preparations with ultrasonic device and diamond CVD (Carbon Vapor Deposition) point, Group 3 control (n=4) teeth without preparation. Deep cavity preparations were as close as possible to the pulp were made. The cavity floor was protected with plasticized gutta-percha, filled with glass ionomer cement and surface coated with varnish. After cavity preparation, teeth were extracted immediately, 7 and 30 days, and submitted to histological procedure. Serial pulp sections were double-blind evaluated by two examiners. Results: Both instrumentation techniques showed similar pulp responses in all experimental periods. Teeth extracted immediately and 7 days showed disorganization of the odontoblastic layer with nucleus displacement into the dentinal tubules, when remaining dentinal thickness was less than 0,27mm. At 30 days, these features were absent, showing reparative dentine formation related to the injured odontoblasts. The greatest level of pulp response correlated with the thinnest dentin remaining thickness (RDT) at the cavity floor. Conclusions: Both methods of cavity preparation were well tolerated by pulp tissue in deep cavities. The pulp response is dependent on the RDT in first two experimental periods, and tends to disappear after 30 days.