Tarek El-Bialy, Donna Galante, Sam Daher
Abstract
Treatment of class III cases with clear aligners maybe a challenge. This is unlike class II where upper molars can be distalized or even do a functional appliance effect. Class III on the other hand, is different. In many growing cases, upper jaw may be required to move forward or restraining lower jaw forward growth in growing children is required. In adult patients, class III management is even more challenging. If a case presented with class III malocclusion that does not have a skeletal component, it can be manageable with clear aligners, however if there is a class III skeletal relationship, orthognathic surgery might be required. Clear aligners still may be used, however careful diagnosis and treatment planning as well as thorough communication with the patients and especially discussion of the treatment expectations is very important before, during and towards finishing of treatment.
* Corresponding author Tarek El-Bialy: Faculty of Medicine and Dentistry 7-020D Katz Group Centre for Pharmacy and Health Research University of Alberta, Edmonton, Alberta T6G 2E, Canada; E-mail: telbialy@ualberta.ca.
Introduction
Class III management may include one of the following strategies: 1) only orthodontic management of the dental class III malocclusion would be aimed at camouflage treatment or backward rotation of the mandible which might help improvement of anteroposterior (AP) correction. However backward rotation of the mandible, although can be advantageous in cases with brachy or meso facial types. Backward rotation of the mandible is usually not recommended in cases with high angle or dolichofacial type. 2) Growth modification in growing children might be aimed at maximizing maxillary growth and harnessing, if possible, mandibular growth and 3) Orthognathic surgical treatment, which may involve maxillary forward surgical repositioning or mandibular surgical backward setback. In many cases, mandibular surgical backward setback may not be recommended in cases with compromised airway or patients having sleep disorders.
Boyd was the first to publish surgical-orthodontic treatment of two skeletal class III patients with Invisalign and fixed appliances [1]. In his protocol, pre-surgical decompensation of upper and lower incisors, coordination of upper and lower arches are done by Invisalign then a pre-surgical partial bonding with fixed appliance is used for intermaxillary fixation, then post-surgical finishing is done by Invisalign.
The possible use of clear aligners in growing class III cases includes: 1) using clear aligners with cuts for elastics to be hooked to face mask should maxillary protraction is an objective for a patient with maxillary deficiency, 2) camouflage treatment in adults if skeletal imbalance may be acceptable. This may be achieved by intermaxillary class III elastics, or 3) use clear aligners for preparation before surgical intervention to correct the skeletal class III malrelationship.
Case Presentation
This is a 16 years and 6 months old male who presented to our clinic with chief complaint that his front teeth are crowded and he had anterior cross bite. His medical history was non-contributory however his oral hygiene was fair and needed improvement. His profile was slightly convex with a dolichofacial type and slight hypermentalis muscle activity (Fig. 8.1). Intraoral photographs and digital models (Fig. 8.2) revealed a class III malocclusion with anterior and posterior cross bites. Also, patient presented with fair oral hygiene that was instructed to improve and visit his dentist for continuous cleanings and checkups. Cephalometric analysis (Table 8.1) revealed class III skeletal with high mandibular angle. Also, cephalometric analysis revealed slightly protruded and proclined upper incisors while lower incisors were within normal range relative to NB plane, however lower incisors inclination to mandibular plane was reteroclined. These axial inclinations confirm the patient has a class III skeletal relationship as per the apical base discrepancy (ANB, WITS analyses).
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