To investigate the incidence and risk factors of open gingival embrasures (OGEs) in the incisor region after treatment with clear aligners in adult non-extraction patients and provide a reference for preventing the occurrence of an open gingival wedge gap in the incisal area after orthodontic treatment.

This study has been reviewed and approved by the institutional medical ethics committee, and informed consent was obtained from the patients. A total of 125 adult patients with malocclusion who completed clear aligner treatment at Hefei Stomatological Hospital from September 2022 to December 2024 were selected as the study subjects. Based on the presence or absence of OGEs in the incisor region observed in frontal intraoral photographs taken immediately after treatment completion, the patients were divided into a normal group and an OGE group. Clinical data, including intraoral photographs, digital models, and cone-beam computed tomography before and after treatment, were analyzed. Measurements such as incisor overlap and rotation, crown morphology, number of attachments, and interproximal enamel reduction (IPR) were recorded and analyzed.

The incidence of OGEs between the maxillary and mandibular central incisors after clear aligner treatment in adult patients was 28.8% and 39.2%, respectively. No statistically significant differences were observed between the normal and OGE groups in terms of sex, Angle's classification, gingival biotype, overbite, overjet, IPR amount, age, treatment duration, tooth axis angulation, or horizontal movement distance of mandibular central incisors before and after treatment (P > 0.05). However, significant differences were found in the number of attachments, anteroposterior distance between mesial incisal angles, distance from the interproximal contact point (ICP) to the alveolar bone crest (ABC) (ICP-ABC), horizontal distance between mesial cementoenamel junction (CEJ) of two adjacent central incisors (CEJ-CEJ) and labial alveolar bone thickness (P < 0.05). IPR amount and mandibular incisor intrusion were significantly associated with the severity of OGEs (P < 0.05). Regression analysis revealed that the number of attachments, anteroposterior distance between mesial incisal angles, ICP-ABC distance, and CEJ-CEJ horizontal distance were significantly correlated with the occurrence of OGEs.

The incidence of open gingival embrasures in the mandibular central incisor region is relatively high among adult patients treated with clear aligners. The number of attachments (n = 2), the anteroposterior distance between the mesio-incisal angles, the distance from the tooth contact point to the alveolar bone crest, and the horizontal distance between adjacent cementoenamel junctions have been identified as risk factors for the development of open gingival embrasures upon completion of orthodontic treatment.

To explore the changes of periodontal soft and hard tissue parameters of the maxillary central incisors after the distant migration of the maxillary total dentition in adult patients with different periodontal phenotypes, so as to provide a reference for orthodontic treatment.

The study was approved by the hospital ethics committee, and the patients signed the informed consent form. Fifty-two adult patients in the orthodontic department of Hefei Stomatological Hospital were selected and divided into thick gingival and thin gingival groups, with 26 cases in each group. The labial and palatal alveolar bone parameters and various periodontal indexes of the maxillary central incisor teeth of the two groups were collected and recorded before and after treatment. SPSS 26.0 statistical software was used to statistically analyze the intra-group and inter-group differences.

After orthodontic treatment, the differences in sella-nasion-subspinale angle (SNA), sella-nasion-supramental angle (SNB), and subspinale-nasion-supramental angle (ANB) were not statistically significant (P > 0.05). However, the inclination of the upper middle incisor teeth (U1-NA) decreased significantly (P < 0.05), and there was no significant difference in SNA, SNB, ANB, and U1-NA between the two groups after treatment (P > 0.05). The thickness of the labial alveolar bone of the maxillary central incisors in both groups increased at the labial neck 1/3 and labial middle 1/3 (P < 0.05), and decreased at the apical 1/3 (P < 0.05). The thickness of the palatal alveolar bone decreased at the labial neck 1/3 and labial middle 1/3 (P < 0.01), and increased at the apical 1/3 (P < 0.01). In both groups, the height of the lip and palate of the upper jaw decreased to different degrees, and the height of the palatal alveolar bone was lower in the thin gingival group (P < 0.05). There were no significant differences in maxillary central incisor probing depth (PD), lip keratinized tissue width (KTW), or lip gingival recession (GR) between the two groups after treatment (P > 0.05).

In the process of maxillary central incisor adduction, the labial-palatine alveolar bone remodeling is not uniform, and the alveolar bone of palatine side is mainly absorbed, which should be paid attention to clinically. Palatal alveolar bone height decreased more significantly in patients with thin gingiva after orthodontic treatment, and the risk of bone fenestration and bone dehiscence was greater.