Risk factors for open gingival embrasures after clear aligners treatment: a retrospective study.

BACKGROUND

To explore the incidence and risk factors of open gingival embrasures (OGEs) in the front region of adult none-extraction cases with clear aligner treatment (CAT).

METHODS

This retrospective study included eighty-two adult patients with non-extraction and CAT treatment, all of which were provided by Invisalign. A total of 820 tooth sites were assessed for OGEs in intraoral photographs. These sites were categorized into nonoccurrence group and occurrence group. The parameters- including crown shape, root angulation (parallel root recorded as zero and divergent root as positive), distance between cementoenamel junction, and distance from interproximal contact point (ICP) to alveolar bone crest (ABC)- were compared between occurrence group and nonoccurrence group using independent t-test and were further analyzed based on the severity. Logistic regression analysis was used to determine the significant risk factors of OGEs.

RESULTS

The overall incidence of OGEs was 13.4% in the maxilla and 30.7% in the mandible. The highest incidence was found between the mandibular central incisors, reaching 39.02%. Age (Maxilla: OR = 1.119, 95%CI (1.048-1.195); Mandible: OR = 1.068, 95%CI (1.018-1.121), mandibular crowding (OR = 0.846, 95%CI (0.729-0.981), distance between adjacent maxillary teeth at the cementoenamel junction (Maxilla: OR = 2.400, 95%CI (1.146-5.027) and distance from ICP to ABC (Maxilla: OR = 8.046, 95%CI (4.016-16.122); Mandible: OR = 3.475, 95%CI (2.390-5.052) in the maxilla and mandible have significant correlation with the occurrence of OGEs (P<0.05).

CONCLUSIONS

OGE is a common complication after CAT, adversely affecting the smiling aesthetics. Clinicians should be well aware of risk factors, such as age, degree of dental crowding, and the distance from the ICP to ABC.