Effect of Porcelain Laminate Contour on Gingival Inflammation

Objectives: The objective of the study was to evaluate the effect of porcelain laminate contour on gingival health. Methods: Seventeen patients requiring 88 porcelain laminates were recruited for the study from the Graduate Restorative Program at the University of Michigan. Gingival crevicular fluid, gingival index, probing depths, gingival recession and clinical attachment levels were recorded at baseline (preoperative), 3 and 6 month recalls. Full arch impressions were taken at baseline, after preparation and after cementation and casts were poured. Residents prepared the teeth according to standard clinical procedures using a depth-cutting bur as a guide. The treated teeth were measured facial-lingually on the casts using a 0.08 thick vinyl stent with reference points (3 on facial, 1 on lingual) from the preoperative cast for caliper placement. The caliper was accurate to 0.05 mm. Tooth reduction, laminate thickness and contour difference were calculated from the measurements made at baseline, post-preparation, and post-cementation. Results: Sixty-five laminates were cemented on maxillary (Max) teeth and 23 on mandibular (Mand) teeth. The averages in mm for tooth reduction, laminate thickness and contour difference were: 0.63 (Max), 0.56 (Mand); 1.16 (Max), 1.10 (Mand); 0.55 (Max), 0.52 (Mand) respectively. At six months there was a general reduction in plaque index (-0.43 Max, -0.73 Mand), gingival crevicular fluid (+7.85 Max, -0.62 Mand) and gingival index (-0.32 Max -0.78 Mand) from Baseline. Using a linear mixed model analysis, the correlation between contour difference and gingival crevicular fluid flow was not significant (p=0.14), although there was a trend; the correlation of contour difference with gingival index was significant (p=0.04). Conclusions: Even when ideal tooth preparations are performed for porcelain laminates, facial over-contour after cementation can be expected at the gingival level. Statistical analysis suggests a positive correlation between facial over-contour and mild gingival inflammation.