Method: Sixty teeth from twenty-six patients with NCCLs were used in the study. Elastomeric impressions and digital images were made of each subject at baseline, one year, and two year recalls. Impressions were poured (low expansion die stone/Fuji Rock/GC). Powder/water (100mg/20ml) spatula hand-mixed for 10sec followed by vacuum mixing (Whip Mix Corporation, Model/6500/ /27psi/30-40sec). Bases were made using putty molds specific to each subject to position casts (baseline/one-year/two-years) with same angulations during scanning. NCCLs on each cast were scanned with a non-contact 3D profilometer (PROSCAN2000) and images at each time period were superimposed (PROFORM) to obtain volume changes of the lesions. To measure biting forces, subjects were seated in upright position, instructed to bite on the prescale pressure indicating tape (Fuji Film) in maximum intercuspation with maximal biting force, which ruptured a red colorant in tape. Color change in the films was scanned and biting forces were calculated (Topaq software full-color pressure map). For each tooth, following were recorded: volume loss of NCCL, gingival height change and total gingival volume change. These were correlated with the recorded biting pressure on that tooth. Data were analyzed using Pearson correlation coefficient and Fisher’s test (α=0.05).
Result: Using Pearson’s coefficient of correlation, biting forces were correlated with the lesion progression from baseline to two years. The correlation of volume loss of lesion to biting forces at 1-year was 0.266 (p=0.1082) and 0.354 (p=0.0234) at 2-years.
Conclusion: 1. NCCL progression is correlated with biting forces at two years (0.354,p=0.0234).
2. Biting forces are correlated with gingival volume loss (0.449,p=0.0147/1yr and 0.585,p=0.0007/2yr) and gingival height loss (0.604,p=0.0153/1yr and 0.697,p=0.0028/2yr).
3. This adds support to the occlusal etiology of NCCL development.
Keywords: NCCL, Abfraction