Effect Of Twin-Block Orthopedic Treatment On Three-Dimensional Morphology Of Maxillofacial Soft Tissue

Objective:1.Using non-radiation structured light three-dimensional scanning technology,the changes in three-dimensional facial size during and after Twin-Block treatment are explored.2.Through models overlapping,the displacement of facial three-dimensional landmarks in the process of Twin-Block orthopedic treatment is described,and the overall mean of displacement is estimated to provide reference for clinical practice.3.The possible factors affecting soft tissue changes in Twin-Block orthopedic treatment are preliminarily explored through the statistical analysis of soft tissue changes before and after treatment.Methods:The patients treated by Twin-Block after clinical examination and diagnosis were collected from the Department of Orthodontics,Hospital of Stomatology,Jilin University,from March 2021 to October 2022.The facial soft tissue data were collected by the structured light three-dimensional scanner before Twin-Block treatment,1.5months,3 months,6 months,and at the end of treatment.After preliminary processing,high-precision three-dimensional digital models were generated and exported to the measuring software,the length and angle were measured by measuring tools,and the three-dimensional changes of landmarks were analyzed by model overlapping.The data were imported into SPSS Statistics 26.0 for statistical analysis to test whether they were statistically significant.Results:1.In the course of the Twin-Block treatment,nasal width,nasal base width,Christa philtri width,width between notches of the lower lip,upper lip length,lower lip length,labiomental angle,the ls-se-li angle changed in different degrees at1.5months,3months,6months and at the end of treatment,and had certain regularity.2.At each time point in the treatment process,labiale superius,labiale inferius,soft tissue B point,soft tissue pogonion,soft tissue gnathion,and soft tissue menton produced different degrees of displacement in the vertical and sagittal direction respectively.3.At the beginning of Twin-Block treatment,overjet,overbite,and labiomental angle were correlated with the prediction of labiale inferius and soft tissue B point displacement.Conclusions:1.Structured light three-dimensional scanning technique is a reliable method to evaluate the changes in facial soft tissue during orthodontic treatment.2.Twin-Block treatment can cause three-dimensional morphological changes of the nose,upper lip,lower lip,and chin,which positively improve the soft tissue deformities of the lower lip and chin.3.The first 3 months of Twin-Block treatment is the key period of soft tissue morphological changes.4.The amount of overjet at the beginning of Twin-Block treatment is related to the prediction of labiale inferius displacement,while labiomental angle and overbite at the beginning of treatment are related factors for predicting the displacement of soft tissue B point.