Lower incisor inclination and thickness of the alveolar process and mandibular symphysis in the development of gingival recession: A retrospective cohort study

INTRODUCTION: Retrospective studies have found conflicting results regarding the relationship between lower incisor inclination and the development of gingival recession (GR) after orthodontic treatment. OBJECTIVE: This study aimed to investigate the relationship between lower incisor inclination and alveolar process (AP) and mandibular symphysis (MS) thickness in the development of GR. MATERIALS AND METHODS: Frontal intraoral photography and cephalometric radiography were conducted before (T0) and after (T1) orthodontic treatment of 62 subjects. The presence of GR was considered when the cementoenamel junction was visible in the lower incisor on the frontal intraoral photograph. The circumstances for improvement, stability, and worsening of the gingival situation were based on the reduction, maintenance, and increase in the number of lower incisors with GR before and after treatment. To measure the incisor-mandibular plane angle (IMPA) and the thickness of the AP and the MS were used the cephalometric radiographs. RESULTS: Men had a significantly thicker MS than women at T0 and T1 (p < 0.0004). There was a significant reduction of approximately 10% in AP between T0 and T1 (p < 0.0001). Among subjects without GR at T0, 70.4% presented a stable gingival situation at T1. For subjects with 1 lower incisor with GR at T0, 50% showed improvement in the gingival situation at T1, 21.4% remained stable, and 28.6% experienced worsening. Sixteen lateral incisors presented a worsening gingival situation, representing an increase of 129% compared to the central incisors. CONCLUSION: No relationship was found between lower incisor inclination and the thickness of the AP and MS in the development of GR.