Orthodontic Angle Classifications: Understanding Class I, Class II, and Class III
Orthodontic angle classifications are used to describe the relationship between the upper and lower teeth and jaws. These classifications are based on the measurements of the angles and positions of the teeth and jaws relative to each other. There are three primary classifications: Class I, Class II, and Class III. Each classification has its own specific characteristics and treatment considerations. In this blog post, we will explore each of these classifications in more detail.
Class I Occlusion
Class I occlusion is also known as normal occlusion. This is the ideal alignment of the upper and lower teeth, where the upper teeth slightly overlap the lower teeth. In Class I malocclusion, the upper molars fit into the grooves of the lower molars, and the upper and lower jaws are in proper alignment.
Class II Malocclusion
Class II malocclusion is characterized by an overbite or retrognathism. This means that the upper teeth and jaw protrude further forward than the lower teeth and jaw. Class II malocclusion is further divided into two subcategories: Class II division 1 and Class II division 2.
Class II Division 1:
In this type of malocclusion, the upper teeth and jaw protrude significantly forward and the lower teeth and jaw are positioned further back. The horizontal overbite, i.e. the distance between the upper and lower teeth, is greater than normal in this classification compared to Class I. This is also reflected in the molar and canine relationship.
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Class II Division 2:
In this type of malocclusion, the upper jaw and incisors are positioned further forward than the mandible. The central incisors in the upper jaw compensate for the horizontal overbite by being retroclined, just as the lateral incisors are often proclined.
As in class II deviation 1, the mandibular front is most often over-erupted, as there is no incisal stop in maximum intercuspidation (MIP)
Class III Malocclusion
Class III malocclusion is characterised by underbite or prognathism. This means that the lower teeth and jaw are positioned further forward than the upper teeth and upper jaw. This can create a bite where the anterior teeth of the lower jaw are positioned in front of the anterior teeth of the upper jaw. Class III malocclusions are often associated with a discrepancy in jaw size, where the lower jaw is larger than the upper jaw, called a skeletal discrepancy.
The treatment for each classification of malocclusion varies depending on the severity and specific characteristics of the case. Class I malocclusions typically do not require orthodontic treatment based on the occlusion in itself. However there may be misaligned teeth that need to be treated with braces or aligners for aesthetic or functional reasons.
Skeletal deviations and impact on the soft tissue
Class II and Class III malocclusions may require more extensive treatment with fixed appliances, with or without surgery. These malocclusions are most commonly seen in patients with skeletal deviations. It should always be considered whether patients with these malocclusions should be treated with or without surgery. This depends on the severity of the malocclusion and the patient's functional occlusion prior to starting treatment.
It is important for dentists to be familiar with the Angle classifications in order to properly diagnose and treat the malocclusion. It is important to note that each classification has an impact on the patient's facial profile and extraoral soft tissues and thus on tongue function, phonetics and aesthetics. All these factors should be taken into account during treatment planning. By understanding the specific characteristics of each classification, dentists can develop a treatment plan tailored to the patient's unique needs.
In conclusion, an understanding of the different orthodontic Angle classifications is an important part of orthodontic treatment planning. Class I, Class II, and Class III malocclusions all have their own specific characteristics and treatment considerations. It is important for dentists to be able to properly diagnose and treat these conditions. With a thorough understanding of these classifications, dentists can help their patients achieve optimal oral health, function and a beautiful smile.
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Many kind regards
Jesper Hatt DDS
Please note that this blog exclusively describes the treatment of adult patients where growth has been completed. Our recommendation is that all paediatric patients and all patients requiring orthognathic surgical treatment are treated by orthodontists. General dentists who treat patients with orthodontic appliances, such as clear aligners, removable appliances or brackets and wires, should at least have extensive training or consult an expert in the field during diagnosis, treatment planning and during the course of treatment.