Class III Diagnosis Treatment

This guide organises possible treatment options for a class III diagnosis. The document is a treatment planning tool to assist you assist how to best treat patients. Treatments are graded by complexity, ranked by the orthodontic technique required, as a guide to the efficacy of treatment and enable providers to select cases that best matches their ability to apply advanced techniques. In this regard, it is particularly useful for dentists who are just beginning to provide clear aligner treatment.

Disclaimer

As doctors are solely responsible for the treatment they’re providing their patients, they should understand their limits and not hesitate to consult a specialist for further guidance when required. Note when applying this guide only general, high-level information on how each isolated condition might be treated is provided. The relationships between different conditions that exist in the majority of patients are not addressed. In this regard, always consider each patient’s individual dental and periodontal condition, restorative needs, facial proportions, and age when considering treatment options.

Class III

Class III

Class III malocclusions are divided into dental and skeletal Class III components. They are the result of “mid-face deficiency” or maxillary retrognathia (a retruded relationship of the maxilla with other facial structures due to a size discrepancy or positional abnormality), mandibular prognathia (a forward relationship of the mandible relative to the craniofacial skeleton), or a combination of both.

It is important to note that full Class III’s are primarily skeletal in nature, and may have a dental component. Typically, the skeletal Class III will have a dentition which compensates for the skeletal base discrepancy, and is characterised by proclined upper and retroclined lower incisors. Cases with major skeletal discrepancies will usually need a surgical/orthodontic treatment approach to achieve ideal results. These cases are characterized by decompensating the dentition followed by a correction of the skeletal bases.

Partial Class III’s may be skeletal or dental and can often be treated with dental camouflage to address the dental relationship component. In this instance, any dental compensations present are usually not corrected, and may even be further accentuated to mask the underlying discrepancy. Because of this fundamental difference in approach, in order to successfully treat a patient with a Class III malocclusion it is of major importance to determine the nature of the problem.

Class III patients can show a displacement between centric occlusion and centric relation. This shift can be caused by anterior occlusal interferences and the patient’s urge to posture into a more comfortable anterior position. Accurately identifying the direction and amount of displacement is important when determining surgical or non-surgical treatment approaches.

For the purposes of Proligner treatment, centric relation bite registration may not be feasible, since the anterior teeth may touch, leaving the posterior teeth out of occlusion. In this instance, it is necessary to take the bite registration in centric occlusion (with the posterior teeth in contact) so that a ClinCheck treatment plan may be generated. The discrepancy between the centric relation and centric occlusion position will have to be kept in mind by the doctor to ensure that the teeth are moved in the ClinCheck treatment plan the appropriate amount.

Once the anterior interference is corrected, it may be possible to capture a more accurate centric relationship bite relationship at the time of refinement.

Dental

Aesthetic alignment only Novice (0-15 cases)

In some cases, a positive overjet cannot be achieved via dental camouflage, even with extractions. Without orthognathic surgery, the only option may be to align the teeth for aesthetic purposes only. Retention for stability may be especially important in these cases, and patients should be fully aware of other treatment options including orthognathic surgery prior to starting treatment.

Advance uppers by aligners/Class III elastics Experienced (16-50 cases)

The goal is to create positive overjet by advancing the upper incisors and retracting the lower incisors using align- ers and Class III elastics. Ideally, there is crowding in the upper anterior area and adequate periodontal support to allow advancement of the upper incisors. Interproximal space and flared incisors are preferred in the lower anterior, in order to upright and retract the incisors.

Advance uppers to make space for restorative Experienced (16-50 cases)

In the event that insufficient arch length is present in the upper arch, spaces may be intentionally created in order to achieve positive overjet, and the spaces filled in using conventional restorative dentistry such as bonding or veneers. The technician should be instructed where to position the space(s) for restorative work.

Retract lowers after IPR Experienced (16-50 cases)

If space is needed for retraction of the incisors, and extraction is not indicated, interproximal reduction can also be used to create the space. Performing IPR distal to the canines may be helpful for retracting the canines into a better Class I canine relationship. If the canines are positioned in Class I relationship and inadequate overjet is present, interproximal reduction between the incisors may be indicated.

Retract lowers by extraction and close space with Class III elastics Advanced (>50 cases)

If inadequate space is present in the lower arch for anterior retraction, space may be created through extrac- tion. Remember that with extraction cases, control of the root position is important for success, and Class III elastics and/or sectional fixed appliances may be needed in addition to aligner treatment.

Skeletal

Aesthetic alignment only Novice (0-15 cases)

Patients unwilling to undergo orthognathic surgery or extractions for dental camouflage may elect for aesthetic alignment of the teeth without changing the posterior bite relationship. Aligners can be used for improvement of the patient’s dental alignment, while preserving the existing bite relationship. Post-treatment retention is especially important for long-term stability.

Extraction/camouflage Experienced (16-50 cases)

Some Class III cases can be treated with dental camouflage using extractions. Proligner can be used for initial alignment and space closure. Depending on the final root position, sectional fixed appliances may also be needed to optimize root position.

Surgery and Proligner treatment Advanced (>50 cases)

Treatment with Proligner combined with orthognathic surgery typically involves the initial alignment and arch coordination phase with Proligner aligners, followed by the orthognathic surgery. Conventional brackets are usually placed immediately prior to surgery for interarch control, with a stainless steel arch wire bent to passively fit inside the brackets. The patient can be finished post-surgically using the archwire for detailing, or with refinement aligners.