Experimental Typodont Study Of Maxillary Teeth Movement Characterized In Closing Space By Individual Lingual Orthodontics

Objective: To establish the typodont models of customized lingual orthodontics, simulate different anchorage to close maxillary extraction spaces using sliding method, observe the differences and characteristics of the maxillary teeth movement among different groups or the same group before?inter and after treatment stages. To provide the guidance for clinical treatment.Methods: Producing Typodont silicone model of Class ? Division 1 classification in space- closing stage, using the silicone model to reproduce 36 sets of typodont wax embankments, dividing randomly into three groups:group A, group B and group C. Each group has 12 sets wax embankments. Using force loaded on both lingul and buccal sides, palatal implant and palatal intermaxillary anchorage respectively, to close extraction space with sliding method, observing and recording the changes in the displacement of the teeth, using SPSS 17.0 statistical software for repeated ANOVA measure analysis.Results: 1. Establishing a repeatable silicone model of Class ?Division 1 classification in space-closing stage.2. Compared with the original model after alignment and leveling stage: the length of the anterior arch decreases, but the total length of the arch is almost the same.3. After closing the gap, the corresponding measurement results of the model in a three-dimensional coordinate system as follows:Group A :(force loaded on both sides): second molar width is 37.33 ± 2.13 mm, which has the minimum reducing amount in the three groups; the reducing amount of arch length 46.59±2.56 mm centered in the three groups; the closing time is 347 ± 13 min, its' speed centered in the three groups; the retraction of anterior teeth is 5.12 ± 1.37 mm, which centered in three groups;Group B :(palatal implant): second molar width is 36.43 ± 1.87 mm, the reducing amount centered in the three groups;the reducing amount of the arch length 45.49±3.16 mm is the biggest; the closing time is 391 ± 29 min, whichis the slowest;the retraction of anterior teeth is 5.87 ± 1.40 mm, which is the biggest in the three groups.Group C :(intermaxillary anchorage): second molar width is35.91±1.56 mm, which has the biggest reducing amount;the reducing amount of the arch length47.3±2.89 mm is the smallest; the closing time is 255±26min, whichis the fastest;the retraction of anterior teeth is5.08±1.11 mm, which is the smallestin the three groupsConclusions: 1. It is feasible to reproduce the silicone model of Class ?Division 1 classification in space-closing stage.2. The results suggest that:1). During the alignment and leveling stages in lingual orthodontics, because of its biomechanic characters, front teeth will have some torque loss accompanied by the posterior teeth upright towards the distal.2). Force loaded on both sides can significantly avoid horizontal bow effecting. Using the palatal implant anchorage alone can also effectively reduce the horizontal bow effecting.3). Force loaded on both sides can quickly and effectively retract the anterior teeth, improve the patient's face type and shorten the treatment. Using the palatal implant anchorage alone can retract the anterior teeth in a maximum extent. But the dentists should pay attention to the control of anterior teeth' torque in both cases in order to avoid significant loss of torque.3. In clinical lingual orthodontic procedures, the dentists should consider the advantages and disadvantages of various anchorages when closing the gap, choose the appropriate method based on the specific circumstances of the patient.