[Evaluation of the efficacy of modified Twin-block appliance combined with micro-implant anchorage in the treatment of Angle Class Ⅱ division 1 malocclusion].

Purpose: To explore the effectiveness of improved Twin block appliances combined with micro-implant anchorage in correction of Class Ⅱ division 1 malocclusion.

Methods: A retrospective analysis of medical records of 96 patients with Class Ⅱ division 1 malocclusion treated at Rugao Hospital of Traditional Chinese Medicine from January 2018 to January 2022 was conducted. The patients were divided into experimental group (n=52) and control group (n=44) based on the treatment methods. The control group was treated with modified Twin-block appliance, while the experimental group was treated with modified Twin-block appliance combined with micro-implant anchorage. Comparison was made between the two groups regarding treatment duration, time to achieve bite opening, alignment time, ANB angle, SNB angle, SNA angle, U1-NA angle, U1-NB angle, U1-SN angle, L1-MP angle, upper lip protrusion(ULP), lower lip protrusion (LLP), Z angle, plaque index (PLI), gingival index (GI) and sulcus bleeding index (SBI). Complications and patient satisfaction were recorded. SPSS 24.0 software package was used for statistical analysis of the data.

Results: The treatment duration, time to achieve bite opening and alignment time in the experimental group were significantly shorter than those in the control group (P＜0.05). After treatment, ANB, U1-NA and U1-SN of the two groups were lower than before treatment, and the experimental group was significantly lower than the control group (P＜0.05). U1-NB and L1-MP were higher than those before treatment, and the experimental group was significantly higher than the control group (P＜0.05). There was no significant difference between SNB and SNA (P＞0.05). After treatment, ULP and LLP of the two groups were lower than before treatment, and the experimental group was significantly lower than the control group(P＜0.05). Z-angle of the experimental group was significantly higher than that of the control group(P＜0.05). PLI in the experimental group was significantly lower than that in the control group (P＜0.05). There was no significant difference between GI and SBI (P＞0.05), and there was no significant difference in satisfaction between the two groups(P＞0.05).

Conclusions: The modified Twin-block appliance combined with micro-implant anchorage can help to shorten the treatment time, improve the jaw and facial soft tissue contour, and promote the recovery of dental aesthetics.