Comparison of operative procedure variables on pulpal viabilty in an ex vivo model

AIM: To measure and compare the responses of pulp tissue to cavity preparation and restoration variables using a novel tooth slice culture model. METHODOLOGY: Experimental cavities (265) were continuously cut, under carefully controlled conditions, into the dentine of the labial aspect of 28-day-old Wistar rat incisors, and slices of these teeth maintained in organ culture for up to 2 weeks. The experimental variables examined were: the preparation method, remaining dentine thickness, coolant, drill speed, conditioning with EDTA and filling materials. The reactions of the dentine-pulp complex to the experimental variables were measured using pathohistometric analysis and the correlations between variables were determined using analysis of variance statistical tests. RESULTS: In rank order of surgically induced restorative pulpal injury, from the most to the least injurious were: remaining dentine thickness, absence of coolant during cavity preparation, bur speed, cavity conditioning treatments and the filling material. CONCLUSIONS: To reduce pulp injury and to promote pulpal repair activity, the correct use of appropriate materials are important. However, of relatively greater importance is the operative technique adopted, the need to avoid the excess removal of dentine and to minimize trauma during preparation.