Objective To study the biomechanical changes of the anterior teeth when the invisible appliance without brackets was used for tooth extraction,and when the micro-implant nail with different heights was used for adduction with 200 g traction force between simple adduction and assisted micro-implantation nails with different heights.Methods One young volunteer with complete teeth and healthy condition was selected and their CBCT data was obtained to establish a three-dimensional finite element model of the maxillary dentition-bracketless invisible orthodontic system.The experiment was divided into a blank control group with only aligner force and groups of 3,4,5,6,7,8,and 9 mm depending on the height of the miniscrew implants.All the above groups,except for the height difference,were powered by 200 g of traction and orthodontic appliance force by miniscrew implants with a cervical power arm on the cusp.The trend of displacement of anterior teeth and the change of stress distribution of the periodontal membrane in each experimental group were then analyzed.Results The addition of miniscrew implants could help to counteract the loss of implant anchorage in the overall inward retraction of the anterior teeth in bracketless aligners.When the height of miniscrew implants was ≤4 mm,the maximum periodontal equivalent force and sagittally inclined displacement of anterior teeth increased with height.The sympathetic displacement of incisors increased with height,and the sympathetic displacement of cuspids decreased with height;all indicators above ≥ 5 mm decreased with height.Conclusion The height of the implant anchorage is recommended to be increased by≥5 mm when the anterior tooth is fully adduced by the invisible appliance without brackets.Moreover,the increase in height facilitates the overall displacement and depression of the anterior teeth.
关键词
无托槽隐形矫治器/整体内收/前牙/微种植钉/生物力学/有限元分析
Key words
clear aligner/overall adduction/anterior teeth/micro implant nail/biomechanics/finite element analysis
维普
万方数据