The effect of cavity restoration variables on odontoblast cell numbers anddental repair

Objectives: Dentinal repair following cavity restoration is dependent on se veral parameters including the numbers of surviving odontoblasts. The purpo se of this study was to examine the effects of cavity cutting and restorati on treatments on post-operative odontoblast numbers. Methods: 353 Standardised non-exposed rectangular Class V cavities. were cu t into the buccal dentin of intact 1st or 2nd premolar teeth of 165 patient s, aged between nine and 25 years of age. Composite cavity restorations wit h various etching treatments were compared with resin-modified glass ionome r cements, enamel bonding resins, as well as polycarboxylate, calcium hydro xide, and zinc oxide eugenol materials. Following tooth extraction (20-381 days) for orthodontic reasons, the area of the reactionary dentine and the area of the odontoblasts was measured histomorphometrically. Results: Odontoblast numbers and dentine repair activity were found to he i nfluenced more by cavity restoration variables, than the choice of cavity f iling materials or patient factors. The most important cavity preparation v ariable was the cavity remaining dentine thickness (RDT), below 0.25 mm the numbers of odontoblasts decreased by 23%, and minimal reactionary dentine repair was observed. Conclusions: Odontoblast injury increased as the cavity RDT decreased. In r ank order of maintaining odontoblast numbers beneath restored cavities with a RDT below 0.5 mm, and using calcium hydroxide for comparison; calcium hy droxide (100%). polycarboxylate (82.4%), zinc oxide eugenol (81.3%), compos ite (75.5%), enamel bonding resin (49.5%) and RMGIC (42.8%). The vitality a nd dentine repair capacity of the pulp is dependent on odontoblast survival . Variations in the extent of odontoblast injury caused during operative pr ocedures, may be the major underlying reason for the success or failure of restorative treatments. (C) 2001 Elsevier Science Ltd. All rights reserved.