Clinical Assessment & Presentations
Extra-oral Features
Start your assessment by looking at the patient’s extra-oral features.
Deficient mid-face and prominent mandible
A concave facial profile can be visible on patients who have a significant skeletal Class III pattern. The facial profile highlights the skeletal base and soft tissue relationships on which a dental malocclusion may be present. A concave facial profile is indicative of a skeletal Class III relationship. The Class III facial appearance can be a deficient maxilla, prognathic mandible or both. Please note that the dental relationships can be quite different to the skeletal or facial pattern – i.e. a patient can have a concave facial profile and skeletal Class III pattern but a dental Class I relationship (dental compensation).
A) Skeletal Class I straight facial profile B) Skeletal Class III deficient maxilla and prognathic mandible facial profile
Protrusive lower incisors +/- lip incompetence
In severe cases of skeletal Class III, the skeletal disparity is large enough that a dental Class I could not be attained naturally (dental compensation). In some cases, the lower incisors are protrusive in facial appearance and there may also be lip incompetence. Patients with such severe cases will often complain of the inability to eat certain foods like sandwiches or pizza as their front teeth do not occlude. They may often also have speech difficulties. Such cases will need specialist care for a comprehensive assessment and a combined surgical and orthodontic treatment.
A severe skeletal and dental Class III pattern. A large reverse overjet is present. The lower incisors are anterior to their ideal aesthetic and functional position. The mandible is prognathic and lip incompetence is present.
Intra-oral Features
Class III incisors relationship
The incisor relationship is a key intra-oral feature as it often the most prominent component of a Class III malocclusion and will often be part of the patient’s chief concerns. The incisor relationship should be addressed in its entirety during orthodontic treatment.
Edge-to-edge and reverse incisor overjet
Class III incisors can present with an edge-to-edge incisor relationship or a reverse incisor overjet relationship. Both of these incisor relationships can lead to excessive dental attrition.
Pseudo Class III incisors
A pseudo Class III incisor relationship can develop when there is an occlusal interference of one or more incisors. This can often occur when incisors are displaced due to crowding or mild ectopic eruption. The interference will often force the patient to advance their mandible forward and upwards (functional shift) to a less uncomfortable bite where the incisors are now in reverse overjet. This is an important incisor classification to identify in growing patients who need to have interceptive treatment so their normal jaw growth can occur.
Pseudo Class III incisors animation
Class III canine relationship
The canine relationships are indicative of the incisor relationships. Left and right canine relationships may be asymmetric due to dental or skeletal displacement. Correction of the canine relationship is often required to enable incisors correction.
Class III molar relationship
Angle’s molar classification is the original method of assessing a Class II malocclusion and still acts as a cornerstone of dental malocclusion classifications. The molar positions are however variable and may not be reflective of the overall malocclusion. Molar drifting can occur due to crowded or missing teeth. Asymmetric left and right molar relationships are often present as well.
