Abstract:

Objective To investigate the clinical efficacy of lingual frenectomy combined with Twin-block orthodontic appliances in patients with mandibular retraction during the growth spurt. Methods Forty-two patients with osseous ClassⅡ malocclusion， characterized by mandibular retraction and short lingual frenulum， who were admitted to our hospital between August 2023 and August 2024， were randomly divided into a control group and an observation group， each consisting of 21 patients. The control group was treated with Twin-block orthodontic appliances alone， while the observation group received treatment combining lingual frenuloplasty with Twin-block orthodontic appliances. Pre- and post-treatment comparisons were made between the two groups regarding treatment duration， Simplified Hazelbaker Assessment Tool for Lingual Frenulum Function （HATLFF） scores， and lingual frenulum length measurements. Oral cone-beam computed tomography （CBCT） was performed in both groups before and after treatment， and three-dimensional reconstruction and cephalometric analyses were utilized to evaluate indicators related to the tongue and hyoid bone， upper airway， maxilla and mandible， and temporomandibular joint. Results The corrective time in the control group （10.14 ± 1.06 months） was significantly longer than that in the observation group （8.00 ± 1.41 months） （P < 0.05）. Before treatment， there were no statistically significant differences between the control and observation groups in terms of simplified HATLFF scores， tongue tie lengths， or indicators related to the tongue and hyoid bone， upper airway， maxillomandibular complex， and temporomandibular joints （P > 0.05）. After treatment， the simplified HATLFF scores and tongue tie lengths in the observation group were significantly higher than pre-treatment values （P < 0.05）. Additionally， IP-CP， IP-RP， ANB， U1-SN， U1-NA angle， and U1-NA distance were significantly reduced in both the control and observation groups compared to pre-treatment levels （P < 0.05）. Conversely， T-S， H-NP， H-CVP， H-Or， H-PP， H-MP， H-FH， H-PNS， total upper airway volume， palatopharyngeal volume， lingual pharyngeal volume， CL-CR， ML-MR， SNB， GoGn-SN， Go-Gn， Co-Gn， Co-Go， Ar-Go， L1-NB angle， L1-NB distance， L1-MP angle， L1-MP distance， SL， SE， Z， UI-PP， L6-MP， articular fossa width， condylar apical sagittal area， condylar height， and condylar apical coronal area were significantly increased post-treatment compared to pre-treatment levels （P < 0.05）. Notably， after treatment， the ANB difference in the observation group was significantly lower than that in the control group （P < 0.05）， while the differences in simplified HATLFF scores， tongue tie length， T-S， H-Or， H-PP， H-FH， total upper airway volume， palatopharyngeal volume， lingual pharyngeal volume， CL-CR， ML-MR， Go-Gn， Ar-Go， L1-NB angle， L1-NB distance， SL， SE， and L6-MP were significantly greater in the observation group compared to the control group （P < 0.05）. Conclusion Lingual tie-plasty combined with the Twin-block appliance demonstrates superior efficacy compared to the single Twin-block appliance in terms of treatment duration and clinical outcomes for patients exhibiting mandibular retraction during the growth spurt..

Key words: mandibular retraction, bony class Ⅱ malocclusion, ankyloglossia, Twin-block orthodontic appliance, lingual tie-plasty, growth spurt, oral cone-beam computed tomography, temporomandibular joints