Experimental Study On The Effect Of Orthodontic Tooth Movement With Thermoplastic Materials Of Different Thickness

The clear aligner is transparent elastic orthodontic appliance with computer-aided designed and manufactured by laser rapid prototyping technique.The related studies have focused on case reports,orthodontic tooth movement and treatment efficiency.Researches on the clear aligner made by different thicknesses of thermoplastic material were rarely reported.This experiment intends to move teeth through the use of compared with conventional ones.So as to explore both the way of tooth movement,amount of tooth movement,expression of tooth movement and periodontal histology.A group of 7 male New Zealand rabbits were randomly divided into three groups: The experimental group(3)was designed to move the lower incisors distally with clear aligners of two different thicknesses(0.625 mm and 0.75mm),0.33 mm distal movement per step was employed;the control group(3)was designed to move the lower incisors distally with clear aligner of conventional thickness(0.75mm),each step incisor tooth movement amount is 0.20mm;and the blank control group(1)was directly sacrificed for histological observation.Polyvinyl siloxane impressions were taken before aligner placement and every four days after each step was finished.Finally,animals’ periodontium were evaluated histologically.The tooth movement of rabbit mandibular central incisor with clear aligner was established successfully.The tooth movement of rabbit mandibular central incisor was tipping with the clear aligner,and the accuracy of incisor movement was decreased from the incisal part to the gingival part.Using different thicknesses of clear aligner can improve the rate of tooth movement,but the accuracy of tooth movement is reduced and the periodontal tissue remodeling is barely different.