Progression of approximal caries in relation to iatrogenic preparation damage.

The aim of the present study was to evaluate the effect of iatrogenic preparation damage on the need for operative caries treatment of approximal surfaces, adjacent to Class II amalgam restorations. The material was collected by 77 dentists from the Public Dental Child Health Service in Denmark. It consisted of die-stone models of 187 first-time Class II preparations, adjacent to 190 unfilled approximal surfaces of 58 primary and 132 permanent teeth. The cavity preparations were performed in children between 4 and 17 years of age. They were all filled with amalgam. Information about operative treatment and exfoliation or extraction of the preparation teeth and the adjacent teeth during the following seven years was obtained from the patients' records. Stereomicroscopic examination of the models revealed preparation damage on 64% of the unfilled approximal surfaces in primary teeth and on 69% of the corresponding test surfaces in permanent teeth. During the observation period, operative treatment was performed on 10% of the undamaged test surfaces in primary teeth and on 35% of the damaged ones (p less than 0.05). The corresponding figures for test surfaces in permanent teeth were 6% and 15% (p less than 0.05). It is concluded that iatrogenic preparation damage is a frequent side-effect of operative intervention with approximal caries lesions, and represents a dental health problem, since the damage increases caries progression and the perceived need for restorative therapy of the adjacent teeth.