A Clinical Study Evaluating The Efficiency Of Intrusion Movement In Anterior Teeth By Removable Clear Orthodontic System

With the popularity of digital reconstruction technology,removable clear orthodontic technology has also been developing.The clear aligners become widely spread in clinic,and its digital model diagnosis system has also been used by more and more people.In the appliance of removable clear aligner,intrusion is one of the routine therapies to open bite.Due to limitations of the material,the efficiency of intrusion by clear aligner is lower than conventional fixed appliance.So,the study discovering the efficiency of anterior intrusion movement by clear removable orthodontic system in different conditions can benefit in better understanding and application of clear aligners.Objective1.Discuss the accuracy of the digital model diagnosis software in clear removable orthodontics system by model measuring and analyzing.2.Compare and analysis the teeth movement after orthodontic treatment by digital model superimposition,discusses the efficiency of anterior intrusion movement by clear aligners.Methods:1.Choose 20 adult patients with clear aligners,obtain initial plaster models and 3D digital models made by clear removable orthodontic system.Arch width and length,tooth width and length,overjet,and overbite obtained from a digital virtual setup model were compared with those from a plaster model.2.The study sample included 22 patients and 101 anterior teeth(44 maxillary and 57 mandibular)treated with clear aligners.To analyze the clinical efficacy,pretreatment and post-treatment plaster cast models were laser-scanned and the achieved tooth movement was determined by digital models superimposition.The results were compared with the amount of tooth movement predicted by clear removable orthodontic system.3.Choose 5 patients whose anterior teeth movement were extrusion in the second experiment for tracking observation.Compare the date of tooth movement and the expected design to make a correlation analysis.Results:1.No difference was found between the 2 groups in the measurement of tooth width,arch width and arch length.The results showed a statistically difference for tooth length,overjet and overbite.However,the magnitude of these differences ranged from 0.08 mm to 0.21 mm and can be considered clinically not relevant.overjet.Repeating measurement reliability was consistent for both the plaster and the digital models.2.The mean accuracy of intrusion movement was 46.9%.The most accurate tooth was mandibular lateral incisors(54.6%),followed by maxillary central incisor(50.9%),and the least accurate tooth was maxillary canines(28.8%).When the teeth were in the process of constriction,the accuracy of intrusion movement would have a significantly statistical difference,and the teeth would likely have an extrusion.3.There is linear correlation between the efficiency of intrusion in the orthodontic treatment and the ratio of adduction and intrusion in the design.The ratio of adduction and intrusion take 62% percent of the influence to intrusion efficiency.Conclusion:1.Digital model diagnosis software in clear removable orthodontic system is precise and reliable.2.The mean accuracy of intrusion movement was 46.9%.The accuracy would decline when teeth were in the process of constriction.3.When constriction is needed,the intrusion design should be increased in order to prevent the elongation phenomenon in anterior teeth.