Navigation Menu
Treatment Indications & Timings
Clinical Assessment & Presentations
scroll down to view
Description
Class II malocclusion
“The relative mesio-distal relations of the jaws and dental arches are abnormal, where the mandibular teeth occlude the maxillary teeth distal to its normal position.”
– Angle 1900
There are two divisions:
The upper arch is usually narrow. It can be accompanied with a lower lip trap and airway compromise.
The upper arch is usually normal or broad in width. There is usually hyperactive lip muscles and normal airways.
Treatment Indications & Timings
Early treatment indications:
➤ Bullying or psychosocial issues due to Class II features
- A child may experience bullying or teasing due to their protrusive incisors or Class II facial appearance. This is a significant indication for early treatment.
➤ Lower lip trap
- A lower lip trap will cause upper incisors to procline without the ability to correct itself.
- Early treatment is indicated to eliminate the lip trap, reduce the protrusive upper incisors and reduce the risk of dental and lip injury.
➤ Habits-induced overjet
- Habits such as thumb or digit sucking can cause proclination of the upper incisors and retroclination of the lower incisors leading to an increased incisor overjet Class II appearance.
- Habit cessation should be sufficient to correct the Class II incisors, however sometimes early treatment is required to assist the correction.
➤ Deep bite with palatal mucosa injury
- A deep overbite with a Class II malocclusion can cause the lower incisors to occlude the palatal mucosa. This will lead to pathologic mucosa stripping and early loss of incisors.
➤ Risk of dental or lip injury
- Approximately 30% chance of young children with a Class II malocclusion will have dental trauma. This injury is often minor and orthodontic treatment lessens the risk but does not eliminate it.
- Soft tissue irritation from a lower lip trap can cause lip abrasion.
Comprehensive treatment indications:
Aesthetic concerns of protrusive incisors
- Aesthetic concerns are not necessarily linked to the severity of the problem however they can be a significant social handicap. (Jolley et al. 2010, Meyer-Marcotty et al. 2010)
Increased incisor overjet
- Whilst there is no strict overjet threshold for treatment, the IOTN (Brook and Shaw 1989) has defined a mild need at > 3.5mm, moderate need at > 6mm and severe need at > 9mm.
Deep bite with palatal mucosa injury
- A deep overbite with a Class II malocclusion can cause the lower incisors to occlude the palatal mucosa. This will lead to pathologic mucosa stripping and early loss of incisors.
Aesthetic concerns of the facial appearance
- A moderate to severe skeletal Class II can result in a reduced mandible and chin appearance that can be a psychological concern to the patient.
Any associated problems requiring treatment
- Crowding, crossbite, anterior open bite, deep bite etc.
- Obstructive sleep apnea, Condylar resorption, Pierre Robin Syndrome etc.
Risk of dental or lip injury
- Approximately 30% chance of young children with a Class II malocclusion will have dental trauma. This injury is often minor and orthodontic treatment lessens the risk but does not eliminate it.
- Soft tissue irritation from a lower lip trap can cause lip abrasion.
Clinical Assessment & Presentations
Extra-oral Features
Start your assessment by looking at the patient’s extra-oral features.
Retrusive mandible and chin
The facial profile should be one of the first assessments for an orthodontic patient as it highlights the skeletal base and soft tissue relationships on which a dental malocclusion may be present. A convex facial profile is indicative of a skeletal Class II relationship.
A clinical profile view of a patient with a retrognathic mandible and chin. There is pronounced facial convexity highlighting the underlying skeletal Class II pattern. (Adapted from Posnick 2015)
The lateral cephalograph of the same patient confirming a significant Class II skeletal base with a hypoplastic mandible and reduced hard tissue pogonion (chin) prominence. (Adapted from Posnick 2015)
Lower lip trap, everted lower lip and/or facially protrusive upper incisors
Adverse lip patterns can often be present with severe Class II incisors and they may also prevent its correction. Facially protrusive incisors are indicative of severely protrusive upper incisors or a very retrusive mandible. If these are present, they are often a patient’s chief concern because of their significant impact to the facial and dental aesthetics.
Intra-oral Features
Class II incisors relationship
The incisor relationship is a key intra-oral feature as it often the most prominent component of a Class II malocclusion and will often be part of the patient’s chief concerns. The incisor relationship should be addressed in its entirety during orthodontic treatment.
Incisor overjet
Not all dental Class II malocclusions are associated with an increased incisor overjet. A Class II div 2 incisor relationship has minimal overjet due to crowding and retroclined incisors. Orthodontic treatment will usually convert Class II div 2 incisors into Class II div 1 incisors and hence an incisor overjet will develop that needs to be addressed.
Class II 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 II 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.
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.