A SURVEY OF FAILURE MODES IN COMPOSITE RESIN RESTORATIONS

This study was undertaken as a first step in identifying opportunities to decrease the need for replacement of class 3, 4, and 5 composite r esin restorations. Data regarding the reasons for original placement o r replacement of a restoration, the age of restorations at the time of replacement, and patient/doctor factors that may be associated with a decision to place or replace a restoration were recorded by use of a cross-sectional survey. During a 2-week period 108 dentists recorded r easons for placing or replacing 1360 restorations. Of the 1360 restora tions, 42.8% were classified as primary placement and 57.2% as replace ment restorations. Of the primary placements 80% were categorized as b eing due to caries; 9.1% fracture of tooth; 8.4% other (erosion lesion s were specified 94% of the time). By class, caries was the dominant c ause for class 3 (96.2%); caries and other (erosion) for class 5 (77.3 % and 16.4%); fracture of tooth and caries (48.9% and 40.2%) for class 4 restorations. The percentages, by category, for replacement restora tions were: Recurrent Decay, 28.6; Marginal Failure, 14.1; Marginal Di scoloration, 21.7; Shade, 4.5; Contour, 1.9; Fracture of Composite, 16 .2; Fracture of Tooth, 8.7; and Other, 4.3%. Lost restorations and ero sion accounted for 76% of the Other category. By class, recurrent deca y, marginal failure, and marginal discoloration accounted for 78% of c lass 3 and 5 replacements but only 36.1% for class 4. Fracture of comp osite was the dominant reason for replacement of class 4 restorations, at 47.0%. For primary placement restorations the breakdown by class w as: class 3, 45.5%; class 4, 15.8%; and class 5, 38.7%. For replacemen t restorations it was: class 3, 42.9%; class 4, 31.1%; and class 5, 26 .0%. The proportions by class were found to differ significantly betwe en the primary placement and replacement groups (chi square, P < 0.000 5). The median age of class 3 restorations at the time of replacement was 10 years, while for class 4 and 5 restorations it was 5 years. Of the existing class 4 and class 5 restorations, 35.5% and 33.3% respect ively were three years old or less at the time of replacement, while o nly 12.8 of class 3 restorations failed over 3 years. The doctor's inc ome, practice location, and type of practice (group or solo) were foun d to have no association with the replacement of a restoration for est hetic or functional reasons. The patient's plaque score was negatively associated with the replacement of a restoration for esthetic reasons ; ie, those with less plaque were more prone to have restorations repl aced. There is an opportunity to increase the longevity of class 4 and 5 restorations by improving the techniques and/or materials used by g eneral practitioners.