[Clinical study on the treatment of Class Ⅱ and ClassⅠmalocclusion in adolescents with mandibular recession using invisible orthodontic appliances without brackets].

Purpose: To explore the application value of invisible orthodontic appliance without brackets in the correction of ClassⅡand ClassⅠmalocclusion in adolescents with mandibular recession.

Methods: A retrospective collection of clinical data was conducted on 114 adolescent patients with ClassⅡand ClassⅠmalocclusion of mandibular retrusion admitted to Hubei Hospital of Traditional Chinese Medicine from February 2020 to October 2022. They were divided into two groups based on different orthodontic methods, with 57 cases in each group. The control group was treated with Twin block appliances, while the experimental group was treated with invisible appliances without brackets. Both groups of patients were corrected for 12 months. The treatment effects of the two groups were evaluated, and the levels of inflammatory factors [alkaline phosphatase (ALP), matrix metalloproteinase-8 (MMP-8), interleukin-1β (IL-1β)] in gingival crevicular fluid before and after treatment, X-ray cephalometric indicators(SNB angle, ANB angle, Go-Gn, Ar-Go), temporomandibular joint parameters (anterior joint space, posterior joint space, superior joint space, fossa height) and upper airway conditions [nasopharyngeal volume (V-nasopharynx), velopharyngeal volume(V-velopharynx), glossopharyngeal volume (V-glossopharynx)], and the subjective perception scores of wearing orthodontic appliance were compared between the two groups. SPSS 28.0 software package was used for data analysis.

Results: There was no significant difference in the orthodontic outcome of the experimental group compared to the control group (P＞0.05). After correction, the levels of IL-1β, MMP-8 and ALP in the gingival crevicular fluid were significantly lower in the experimental group compared to the control group(P＜0.05), but there was no significant difference(P＞0.05) between the two groups in terms of SNB angle, ANB angle, Go Gan, Ar Go, anterior and posterior joint spaces, supraarticular space, and joint socket height. After correction, there was no significant difference(P＞0.05) between the two groups in V-glossopharynx, V-palatopharynx, and V-nasopharynx. The experimental group had significantly higher scores in terms of comfort, compliance, and aesthetics when wearing invisible orthodontic appliances without brackets compared to the control group(P＜0.05).

Conclusions: The treatment effect of Twin-block appliance and non-bracket invisible appliance is comparable for Class Ⅱ division Ⅰ malocclusion in adolescents with mandibular retrognathia. Both can improve the morphology of the mandible and dentition, expand the upper airway, but non-bracket invisible appliance can further reduce inflammation and improve patients' comfort.