Evaluation of Proximal Contacts of Posterior Composite Restorations with 4 Placement Techniques

Background: Contrary to the situation for amalgam restorations, obtaining acceptable proximal contacts with posterior composite restorations can be difficult. Proximal contacts that are less than ideal may permit food impaction and subsequent caries formation and periodontal problems.Purpose: The aim of this study was to assess the quality of proximal contacts of posterior composite restorations placed with 4 restorative techniques.Methods: Seventy-five mounted ivorine teeth with large, standardized MOD cavities were divided into 5 groups of 15 teeth each. The teeth in 4 of these groups were restored with a resin composite and those in the remaining group were restored with amalgam. The restorative techniques for the 4 composite groups were traditional wedge and matrix (Group 1), use of a light-tip attachment (Group 2), use of the Contact Pro hand instrument (Group 3) and useof Beta Quartz glass-ceramic inserts (Group 4). All restorations were completed under simulated clinical conditions.Standards for evaluating proximal contacts were set by preparing 4 dental study models, each model having one type of proximal contact (open, not tight enough, ideal and too tight). All restored teeth were carefully painted with opaque nail polish, except at the contact areas, to conceal restoration type and hence to ensure unbiased evaluation by assessors. Three experienced clinicians independently assessed the quality of the proximal contacts of all restored teeth (total of 150 contacts) relative to the 4 types of contacts exemplified by the dental study models. In cases of disagreement, the clinicians reassessed the disputed contact collectively.Results: Amalgam restorations had 5 contacts that were not tight enough, 20 that were ideal and 5 that were too tight. The Group 1 composite restorations had a total of 25 open contacts and 5 contacts that were not tight enough; the Group 2 composite restorations had 3 open contacts, 13 contacts that were not tight enough and 14 that were ideal; the Group 3 composite restorations had 11 contacts that were not tight enough and 19 that were ideal; and the Group 4 composite restorations had 3 contacts that were not tight enough and 27 that were ideal. None of the composite contacts was judged too tight.Conclusions: The use of inserts (Group 4) resulted in a better rate of acceptable proximal contacts in posterior composite restorations than the 3 other techniques (90% vs. 0%, 47% and 63% for Group 1, Group 2 and Group 3, respectively).