Relationship between mandibular incisor inclination and periodontal parameters among patients undergoing non-extraction orthodontic treatment: A cohort study

The interrelationship between orthodontics and periodontics is well documented. Periodontal alterations frequently occur during orthodontic treatment. This study aimed to determine the possible changes in mandibular incisor inclination and their effects on periodontal health before, during, and after orthodontic treatment. This cohort study included 61 eligible patients who underwent non-extraction orthodontic treatment for changes in mandibular inclination. All orthodontic norms for SNA (Sella, nasion, A point), SNB (Sella, nasion, B point), ANB (A point, nasion, B point), FMA (Frankfort-mandibular plane angle), and incisal mandibular plane angle (IMPA, mandibular incisor-to-mandibular plane angle) were evaluated using lateral cephalometric radiographs. The types of malocclusion and divergence were recorded based on orthodontic norms. Periodontal parameters, including periodontal pocket depth, clinical attachment loss (CAL), keratinized tissue width, plaque index, and gingival index, were recorded at 3 periods (1-month pre-debonding, peri-debonding, and 2 months post-debonding). Descriptive statistics, Pearson correlation, and analysis of variance (ANOVA) followed by Tukey multiple comparison test were applied to the data. During the pre-debonding stage, most periodontal parameters were within normal healthy conditions, except for CAL, which varied from 0.96 mm to 1.55 mm. The mean width of keratinized gingiva was ≥4 mm. The correlations between changes in IMPA and periodontal pocket depth and changes in IMPA and CAL ranged from -0.018 to 0.236 and -0.048 to 0.179, respectively, suggesting a very weak, nonsignificant correlation after orthodontic treatment (P >.05). Orthodontic treatment of mandibular incisor inclination does not seem to significantly correlate with bleeding on probing, plaque accumulation, probing pocket depth, clinical attachment level, and the width of keratinized gingiva. Hence, it can be inferred that orthodontic treatment of mandibular incisor inclination has no impact on periodontal parameters.