IPR treatment and attachments design in clear aligner therapy and risk of open gingival embrasures in adults

Abstract

Background The incidence of open gingival embrasures (OGE) in patients after fixed appliance treatment is relatively high, while there are no detailed reports on patients after clear aligner therapy. Also, no clinical studies with large sample size have investigated whether interproximal enamel reduction (IPR) can actually avoid OGE. The purpose of this study was to determine the prevalence of OGE in adults after clear aligner therapy and to investigate the risk of OGE associated with IPR treatment and attachment design, focusing on the amount and distribution in mandibular anterior teeth. Methods Pre-treatment and post-treatment intraoral frontal photographs of 225 non-extraction patients were evaluated retrospectively for the occurrence and severity of OGE. The amount of IPR and the number of attachments in the anterior teeth from subjects after screening were recorded according to the first version of clear aligner software (Clincheck, San Jose, USA) and clinical medical documents. Logistic regression analysis was performed to identify the factors contributing to OGE. Results The incidence of OGE in non-extraction patients after clear therapy between maxillary and mandibular central incisors was 25.7% and 40.3%, respectively. IPR was not associated with the occurrence of OGE but was associated with severity (P < 0.05). The number of attachments in the anterior teeth or central incisors was significantly related to the incidence of OGE (P < 0.05) but was not associated with severity. Conclusion A high rate of OGE occurs after clear aligner therapy. Clinicians should be aware of the application of IPR and the design of attachments during clear aligner therapy.

The incidence and severity of open gingival embrasures in adults treated with clear aligners and fixed appliances: a retrospective cohort study

“…A triangular-shaped crown may also be related to “scalloped-thin” gingiva that experiences higher risks of deficient papilla [ 31 , 33 ]. No relationship between IPR and the incidence of OGEs was observed in a recent research [ 5 ]. Similarly, no significant difference was found on crown ratio, root angulation or the amount and distribution of IPR between the two groups in our present study.…”

“…Several key issues, such as cost difference between the expensive clear aligners and the relative cheap fixed appliances, patient preference for appliances, and case selection, make randomized controlled tests difficult. For example, socio-economic factors may affect the patient's motivation for dental health and periodontal treatment; in addition, orthodontists may recommend clear aligners for cases who need arch expansion and prefer IPR in treatment with aligners [ 5 , 35 ]. Therefore, multicenter randomized controlled trials are needed to explore the difference in the incidence of open gingival embrasures in future studies.…”

“…Moreover, extraction of lower incisors leads to a high incidence of OGEs in an early clinical evaluation [ 4 ]. The severity of OGEs was also pointed out to be associated with IPR in a study recently [ 5 ].…”

Biomechanical factors in the open gingival embrasure region during the intrusion of mandibular incisors: A new model through finite element analysis

“…Clear aligners are becoming increasingly popular due to their excellent aesthetic value, although these aligners are also associated with aesthetic problems such as OGE. In our previous study, we found the incidence of OGE in non-extraction patients after clear aligner therapy was relatively high at 25.7% and 40.3%, respectively, between the maxillary and mandibular central incisors ( Zhang et al, 2023 ). The biomechanics of clear aligners differ from those associated with fixed appliances.…”

The Role of Interproximal Reduction (IPR) in Clear Aligner Therapy: A Critical Analysis of Indications, Techniques, and Outcomes

“…This phenomenon may be pre-existing in the patient prior to treatment initiation, or black triangles may emerge during the treatment, particularly following the alignment of rotated incisors [29]. In the study conducted by Zhang et al, upon comparing the occurrence of black triangles between fixed appliance and clear aligner therapies in non-extraction cases, a heightened incidence of gingival embrasure opening was observed undergoing clear aligner therapy, with rates of 25.7% for maxillary incisors and 40.3% for mandibular incisors [30]. In contrast, fixed appliances exhibited incidences ranging from 22% to 36% [31].…”