Abstract: Aim and Hypothesis Gingival recession is a common defect of the periodontal soft tissues, whose prevalence has been estimated between 50% and 70% of the population. Gingival recession is more common in individuals with thin biotype than those with thick biotype. While an autogenous connective tissue graft is the gold standard, acellular dermal matrix (ADM) is an acceptable alternative ma... read moreterial for the treatment of such a defect. The present study aimed to investigate the impact of gingival biotypes on the outcomes of root coverage procedures performed with ADM. The hypothesis in this study is that the thick biotype group will achieve higher percentage of root coverage at 3 months. Materials and Methods: The study included 10 patients with thick and 11 with thin biotype. Each patient had two adjacent recession defects. Thick biotype was defined as gingival thickness0.8 mm while gingival thickness <0.8 was considered a thin biotype. In both groups, a coronally positioned flap was utilized to cover a standard sized piece of ADM over the defects. Clinical measurements including recession height (RH) and width (RW), gingival thickness (GT), keratinized tissue width (KTW), probing depth (PD), bleeding on probing (BOP) and clinical attachment level (CAL), were measured at baseline and at 3 months follow up. A patient survey evaluating sensitivity, esthetics and pain was collected at baseline and at 1 week, 3 weeks and 3 months follow-up visits. For between-group analysis, the independent samples t-test was used if the data was normally distributed, while the Mann-Whitney U test was used if the data were not normally distributed. For within-group analysis comparing baseline and 3-month data, the paired samples t-test or the Wilcoxon signed-rank test were used if the data were not normally distributed. Alpha was set at 0.05 to obtain a power of 99%. Dentinal hypersensitivity was compared between groups at baseline, and the changes in sensitivity at 3 weeks and 3 months were also compared between groups. Similarly, complication rates were compared between the two groups at 1 and 3 weeks post-surgery. Results: Between baseline and at 3 months, both groups achieved statistically significant reduction in RH (thick: from 2.63±0.57 mm to -0.02±1.47 mm , p <0.001; thin: from 2.62±0.33 mm to 0.18±1.18 mm, p <0.001) and RW (thick: from 3.30±0.62 mm to 0.00±0.62 mm, p = 0.001; thin: from 3.80±1.44 mm to 0.72±2.22 mm, p<0.001). The differences in the reduction between the groups was statistically not significant (RH: p=0.480; RW: p =0.557). The differences in terms of percent root coverage, either capped (thick: 100.00±28.00%, thin: 92.36±62.80%, p = 0.282) or non-capped (thick: 115.16±54.68%, thin: 95.12±14.7%, p = 0.387), was found to be statistically non-significant. At three months, the comparison between the groups yielded a significant difference between groups for KTW, (thin: 1.58 ± 0.62 mm versus thick: 2.49 ± 0.96 mm, p = 0.017), and GT (thin: 1.21 ± 0.30 mm versus thick: 1.58 ± 0.20 mm, p = 0.004). Within the groups, differences for GT (thin: from 0.59±0.14 to 1.21±0.30), the CAL (thin: from 4.48±0.74 to 3.38±1.21; thick: 4.65±0.97 to 2.22±1.41) were judged to be statistically significant, (p=0.003 and p=0.02 for GT and CAL respectively). The frequencies for complete root coverage, were 63.6% and 80% in the thin and the thick groups respectively. Baseline comparison between dentinal hypersensitivity scores was not significant (thin: 5±4; thick: 3±5 p=0.847). Similarly, the changes in dentinal hypersensitivity between baseline and 3 weeks, (thin: 1±4; thick: 3±4, p=0.193), 3 weeks and 3 months, (thin: 0±4 and thick: 0±1; p=0.056), and baseline and 3 months (thin: 3±5; thick: 2±3, p=0.562), were not statistically significant. Since the data was not normally distributed, the Mann Whitney U-test was used to compare groups. Complication rates at one and three weeks yielded no statistically significant difference between groups, (one week: thin: 40%; thick: 27.3%, p=0.659; three weeks: thin: 20%; thick: 27.3%, p=1.00). Chi-square test was used to compare complications between groups. Conclusions: Both groups in the present study achieved a high degree of root coverage and were associated with a high frequency of complete root coverage at the three-month follow-up. The gingival thickness increased by a similar degree in both groups and at three months, both had a gingival thickness greater than 0.8 mm. Within the limits of the study, it is concluded that ADM is effective in treating moderate multiple gingival recessions for both biotypes. As a side benefit, it thickens the gingival tissue and may convert a thin biotype to a thick one.
Thesis (M.S.)--Tufts University, 2016.
Submitted to the Dept. of Periodontology.
Advisor: Wai Cheung.
Committee: Charles Hawley, Bjorn Steffensen, and Matthew Finkelman.