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ePaper created 2017-09-06, 09:11:22 | version 1.38.0
inclination of the incisors. The Class II elastics were responsible for mandibular protraction of about 1.5 mm. Retention was provided by Vivera retainers (Align Technology) (Figs. 6, 7a–c, 8a–c). Discussion and conclusion In several studies conducted on Class II intraoral non-compliance appliances, dentoskeletal efects revealed anchorage loss at the reactive part, distal tipping and extrusion of molars.12 Usually, the anchorage loss occurred particularly in the incisal area owing to the reciprocal force reacting to the distalising force. Previous studies have confirmed that the use of Class II elastics during maxillary molar distalisation with aligners prevents the uncontrolled proclination of the anterior teeth.13 Furthermore, the sequential distalisation proto- col limits space opening between the distalising teeth, which is more aesthetic, maintains maxi- mum aligner contact with the teeth and reduces the flexibility of the plastic material. That, in turn, minimises uncontrolled incisal tipping, which is expressed clinically as increased overbite with a loss of palatal root torque. Treatment duration is influenced by the mal- occlusion complexity, the amount of tooth move- ment required and the applied system of forces. The distalisation of maxillary molars is frequently required in Class II non-extraction patients. Re- solving Class II molar relationships by distalising maxillary molars may be indicated for patients with minor skeletal discrepancies.14 Simon et al. reported a high accuracy (88%) of the bodily movement of maxillary molars with CAT when a mean distalisation movement of 2.7 mm was prescribed.15 The authors reported the best accuracy when the movement was supported by the presence of an attachment on the tooth sur- face. Furthermore, they underlined the importance of staging in the treatment predictability. Ravera et al. investigated the dentoskeletal efect of max- illary molar distalisation with Invisalign aligners in adult patients and found that clinicians can con- sider the use of Invisalign aligners in treatment planning for adult patients requiring 2–3 mm of maxillary molar distalisation.16 In order to obtain this amount of movement, maxillary third molars, if present, should be extracted to have suficient room to move the second and first molars in Class II malocclusions. It has been suggested that teeth moved with aligners do not undergo the typical stages of orthodontic tooth movement described by Krishnan and Davidovitch,17 because of the in- termittent forces applied by the aligners. However, light continuous forces are perceived as intermit- tent by the periodontium18 and orthodontic inter- maxillary molar distalisation with aligners case report mittent forces are able to produce orthodontic tooth movement with less cell damage with respect to light continuous forces.19 Cyclic forces applied by the AcceleDent device are oscillatory in nature and change in magnitude rapidly and repeatedly, afecting the cells with each oscillation of force magnitude.20 The fre- quency of cyclic forces is never zero. Force fre- quency is a concept of critical importance, but has rarely been considered in the field of ortho- dontics and dentofacial orthopaedics until recent years. Cells are known to respond more readily to rapid oscillation in force magnitude (i.e. to cyclic forces) than to constant forces.7 Therefore, Ac- celeDent acts as a physical mediator of the bone modelling and remodelling processes behind or- thodontic tooth movement, thus facilitating the action of the aligners. The result is excellent track- ing of the aligners, because of the expression of the biomechanics produced by the interaction between aligner, attachments and tooth surface (Fig. 9). The successful incorporation of Accele- Dent into an orthodontic treatment can signifi- cantly reduce treatment time, making it an at- tractive adjunct for patients. In the presented case, treatment duration was shortened by 45% with an effective, user-friendly and safe technique. about Dr Tommaso Castroflorio is an adjunct professor at the Department of Surgical Sciences of the CIR Dental School at the University of Turin in Italy. He can be contacted at: tommaso.castroflorio@gmail.com ortho 2/2017 31