Dental Tribune United Kingdom Edition

In developing the Inman Aligner, Donal Inman CDT cre- ated a patented design that takes advantage of the gentle, steady and consistent forces generated by NiTi. The design relies on piston-like components driven by NiTi coil springs. Inman de- signed lingual and labial com- ponents to function or move in parallel to the occlusal plane, eliminating the mousetrap-like unseating forces and allowing actual physiological movement of teeth. Inman Aligners are ide- ally worn for 16 to 20 hours a day. Studies have demonstrated that the removal of orthodontic forces for four hours a day mas- sively reduces the risk of root resorption1 and that risk of root resorption is lower in removable versus fixed appliances.2 A standard Inman Aligner as described in the following cases consists of both lingual and la- bial components. The forces have the effect of squeezing the teeth into align- ment. The components can be used in isolation to retract teeth with a more steady force, requiring less adjustment than a standard labial bow retrac- tor. In Case III, a unique ap- proach that incorporates an expander on the Inman Aligner is described. Patient selection Case selection for the Inman Aligner is critical. The following criteria should be met before treatment pro- ceeds: 1. Cases should require move- ment of incisor and/or canine teeth only. 2. Root formation of the teeth to be moved must be complete. 3. Crowding or spacing should be less than or equal to three mm. Arch evaluation must be performed to determine the amount of space required. Cases with over three mm of crowding require additional space crea- tion techniques, as pioneered in the UK, which should only be attempted with training. It is quite possible to treat cases with 5.5mm crowding eas- ily and predictably in less than 16 weeks. 4. Cases should have fully erupt- ed posterior teeth to facilitate re- tentive clasps, with a reasonably well-aligned arch form to facili- tate the path of insertion of the appliance. 5. Cases should be stable and preferably free from periodontal disease. 6. Patients must agree to wear the Aligner for about 20 hours a day and be responsible for good appliance and oral hygiene. Should the patient wear the Aligner for 14 hours a day only, treatment will still be successful. Model evaluation/arch anal- ysis with Spacewize Arch analy- sis should be performed before any Aligner case is attempted in order to ensure that the case is suitable and, if not, what addi- tional space creation techniques will be needed to allow the In- man Aligner to work. The extent of crowding present is calculat- ed3 by measuring the sum of the mesial-distal widths of the teeth to be moved. This distance is called the required space or the teeth. If canines and incisors are to be moved, this distance will be measured from the distal sur- face of one canine to the distal surface of the other canine. Using an orthodontic retain- ing or jeweller’s chain or a pol- ishing strip, the ideal arch form is then measured from the distal of each canine in alignment with the ideal arch form following or- tho dontic correction. Critically, the arch needs to pass through the suggested po- sition of the contact points and not the incisal edges. This is de- scribed as the available space or the curve. It is possible to perform this task more quickly and just as ac- curately with software such as Spacewize. Just one simple oc- clusal photograph is required, which can be taken chairside. One tooth needs to be meas- ured for calibration. A curve can be digitally established and this is normally easier when ob- serving the patient’s aesthetic requirements and occlusion di- rectly. The extent of crowding is immediately calculated using such software. Laboratory requirements Accurate upper and lower im- pressions are taken, preferably two of the arch being treated. Simple alginate can be used if cast quickly. A bite registra- tion and prescription should be completed and sent to a certi- fied Inman Aligner Laboratory. The technician should be in- formed of the amount of crowd- ing calculated. The teeth to be repositioned should be noted clearly. The prescription should provide full details to the tech- nician regarding the teeth to be moved, the area they are to be moved to and the distance they are to be moved. A Spacewize trace of the ideal curve can also be submitted. Interproximal reduction Interproximal reduction (IPR) is begun at the fitting appointment using abrasive strips or discs. The model analysis will have already calculated the extent of IPR required. Many authors acknowl- edge that the reduction of half of the interproximal enamel on the mesial and distal of each incisor tooth is a safe technique.4–7 This equates to 0.5mm per contact point, creating 2.5mm of space between the canines. In some cases, the distal of the canine and mesial of the premolar can be reproximat- ed allowing for a total of 3.5 to 4.5mm. These cases will re- quire more experience in using the system but offer a number of possibilities for clinicians once trained to use the system correctly. Meticulous records of the amount of stripping performed should be kept. An in-surgery fluoride rinse or application of topical fluoride is recom- mended after any enamel reduc- tion procedure. El-Mangoury et al.8 and Ra- dlanski9 have demonstrated that there is no increased risk of car- ies after IPR, provided surfaces are smoothed correctly. Heins et al.10 and Tal11 have demon- strated that there is no increased risk of periodontal disease, despite the decreased interprox- imal space. Critically, Inman Align- er treatment uses progres- sive, anatomically respectful IPR. While the extent of IPR required is already known, it is never carried out in one treat- ment. In order to ensure mini- mal risk, IPR (0.13mm per visit per contact point) is carried out only in small increments. The patient is sent away with the Aligner. Owing to the Aligner forces, the gaps will be closed after two weeks. Interproximal reduction is performed at each appointment only as needed, using strips or discs, which ensures the stripping is far more anatomically conserva- tive than would be the case using burs. This significantly re- duces the risk of excess space ormation, gouging or poor con- tact anatomy. Lingual/labial anchors Composite resin just incisal placed either incisal or gingival to where the bows contact will help them to function more ef- ficiently. This can also be used for the labial surface, especially in cases in which teeth are being retracted. Strategic placement is vital for success and can be very helpful in the treatment of ro- tated teeth and the extrusion of teeth. Appliance adjustment The forces can be varied by ad- justing the spring components or replacing springs for larg- er, longer springs. Generally, adjustments are not neces- sary, except in more complex cases, for which training is re- quired to understand the correct spring types and compression rates to use. page 18DTà Fig. 1 Side smile view before treatment Fig. 3 Occlusal view before treatment Fig. 2 Side smile view after nine weeks with an Inman Aligner Fig. 4 Occlusal view after treatment 17ClincialFebruary 7-13, 2011United Kingdom Edition ‘The forces have the effect of squeezing the teeth into alignment. The components can be used in isolation to retract teeth with a more steady force, requiring less adjustment than a standard labial bow retractor’ page 15DTß