Diagnosis & Considerations
The diagnosis can be a dental Class II (dental displacement), skeletal Class II (skeletal displacement) or a combination of both.
A dental or skeletal Class II will have different subtypes and their diagnosis is usually derived by history taking and a clinical examination supported by radiographs and dental models.
Dental Class II
- A dental Class II occurs if a patient has Class II buccal segments (canines and molars) and/or Class II incisor relationships. See the intra-oral appearance of a dental Class II here.
- It is important to diagnose the position of the lower and upper incisors within the alveolar bone to determine the level of dental compensation present on a Class II skeletal base.
- Asymmetries of left and right side dental relationships, called subdivisions, often exist.
- The aetiology can be multiple factors including early loss of deciduous teeth/leeway space leading to mesial drifting of teeth, tooth-arch size discrepancy, malformed teeth, supernumerary teeth, retained deciduous teeth or ectopic teeth.
Skeletal Class II
- A skeletal Class II jaw relationship can occur with or without a Class II dental malocclusion.
- It occurs when the mandible is more posterior to its normal position relative to the maxilla. See the extra-oral appearance of a skeletal Class II here.
- According to the Steiner’s analysis, a skeletal Class II is an ANB ≥ 5 degrees for caucasians and an ANB ≥ 6 degrees for asians and blacks.
- According to the Wits analysis, a skeletal Class II is a Wits value of > 1mm.
- There are several types:
- Mandibular retrognathism (most common)
- Maxilla prognathism
- A combination of the above
- There are also several subtypes of mandibular retrognathism. For more information see our skeletal malocclusion section.
- Asymmetries may exist.
- The aetiology of mild to moderate cases are often unknown and can be considered part of the normal genetic variation of size and position of the jaws.
- The aetiology of severe cases can be several factors including in-utero developmental disturbances (e.g. craniofacial microsomia and Stickler’s syndrome), in-utero growth disturbances (e.g. Pierre Robin sequence and intra-uterine moulding) and childhood and adolescent growth disturbances (e.g. jaw fractures, condylar resorption, muscle dysfunction secondary to injury or disease and disease affecting the TMJ).
Clinical Considerations
Determine the aetiology of the dental and/or skeletal Class II
- Treatment should be targeted to diagnosis and aetiology. The relevant mechanics, appliances and possible need for surgery can be planned accordingly.
- Multiple diagnoses are often present. For example, a patient with a skeletal Class II hypoplastic mandible may have Class I molars and Class II canines and incisors, with mid-arch dental crowding, posterior crossbites and dental arch asymmetry.
What is the growth status?
- The growth status of the patient will influence the possibility if the Class II pattern will improve, worsen or remain consistent with growth.
- The growth status will also influence if early treatment, growth modification or surgical treatment options are available to the patient at their current age.
Should the Class II be corrected?
- Class II occlusion is common in the population and Class II molars have not been associated with poorer oral health or quality of life outcomes.
- Treatment decisions should hence be based on other treatment indications rather than a Class II buccal segment.
The morbidities and compromises of different treatment options
- The number of treatments and the duration of treatment can cause significant burden to the patient and parents. Patient burnout needs to be considered particularly if shorter and more effective treatment options are available instead.
- Orthodontic camouflage to correct a Class II malocclusion often means a compromise on retracting upper incisors or proclining/flaring lower incisors. If significant camouflage is required, then a compromise on upper lip support, facial aesthetics, smile appearance and periodontal integrity will result.
