The Clinical Efficacy Of Invisalign On Maxillary Molar Distalization In Adult Using Three-Dimensional Laser Scanning

ObjectiveThe aim of the present study was to evaluate the clinical efficacy of Invisalign on distalizing maxillary molars and the effect of the anchorage teeth using the three-dimensional laser scanner technology and the two-dimensional cephalogram.MethodsTwenty-two non-growing subjects(1 male,21 female;average age 29.6 years)meeting the inclusion criteria and exclusion criteria who needed Maxillary molars distalization with Invisalign were selected in our study.Plaster cast models and cephalograms were taken at two time points: pretreatment and post-distalization.The three-dimensional digital models were created from a 3_Shape Trios 3 laser scanner(3Shape,Copenhagen,Denmark).We measured the actual movement of the Maxillary first molar,first and second premolar and central incisor on three-dimension using Rapidform2006 software(INUS Technology,Seoul,Korea),comparing with the predicted movement from ClinCheck(Align Technology,Santa Clara,CA,USA).We also measured cephalograms about dental and skeletal changes.SPSS 17.0 software was used for statistical analysis.Result1.The first maxillary molar has significant differences between the actual and predicted movement posteriorly on three-dimensional digital models superimposition measurement(P=0.0001).The first maxillary molar actually moved distally 2.04±0.92 mm,the predicted movement distally was 3.16±1.08 mm,and the efficacy is 64.56%.In contrast to predicted changes,the first upper molar had distal tipping of 5.44 degrees,crown buccal torque of 3.71 degrees,and intrusion of 0.55mm(P=0.0001).2.In contrast to Clin Check predicted changes,the mesial tipping and buccolingual inclination of the maxillary second premolar had no statistically significant differences(P=0.259,P=0.125).The mesial movement of the maxillary second premolar was 1.07 mm,with a significant difference(P=0.0001).The mesial movement,the mesial tipping and buccolingual inclination of the maxillary first premolar and maxillary central incisor all had a statistically significant differences(the maxillary first premolar P=0.0001,P=0.04,P=0.03;maxillary central incisor P=0.0001,P=0.002).The maxillary first premolar had mesial movement of 1.11 mm,mesial tipping of 1.37 degrees,crown buccal torque of 2.15 degrees.The maxillary incisor had mesial movement of 1.12 mm,and crown labial torque of 2.03 degrees.3.The results of cephalometric measurement showed that the maxillary first molar moved distally 2.28 mm,and had distal tipping of 6.38 degrees.The mandibular plane angle showed no significant differences between pre-and post-distalization cephalograms(P=0.717,P=0.545).Conclusions1.The Invisalign appliance can distalize maxillary molar relatively effectively(64.56%),which can solve clinical problems,while there was slightly distal tipping,crown buccal inclination of the first maxillary molar.And the efficacy was expected to be improved.Meanwhile,there was anchorage loss in anchorage teeth,which remindered clinician to control anchorage and increase predicted changes.2.During the molar distalization using Invisalign appliance,the maxillary first molar had the intrusion,and the mandibular plane angle didn’t increase,meaning we can try to distalize molar in dolichofacial individuals,but need close clinical observation and supervision.