Short answer: Class II and Class III are orthodontic terms that describe the front-to-back position difference between the upper and lower jaws. In Class II the lower jaw sits behind the upper jaw, and in Class III it sits in front. Management is planned according to age, growth status and whether the problem is dental or skeletal.
What is the classification based on?
In orthodontics, the bite is divided into three classes by looking at the position of the molars and the jaws relative to each other. Class I is the arrangement in which the teeth close in harmony with each other; problems such as crowding can also be present in this class. Class II and Class III refer to anteroposterior mismatches, that is, mismatches in the front-to-back direction.
Class II bite
- The upper teeth and jaw appear to sit further forward than the lower teeth.
- The lower jaw may be set back or perceived as small; the side profile may look retracted.
- The horizontal distance between the front teeth increases; in some people the teeth appear to stick out.
- In some individuals the front teeth are tilted inward and the bite is deep.
For these terms, you can have a look at our article on retrognathia, prognathism and protrusion.
Class III bite
- The lower teeth sit in front of the upper teeth; a reverse bite (crossbite) is seen in the front teeth.
- The cause can be a recessed upper jaw, a forward-growing lower jaw or both.
- It can show a tendency to run in families.
Dental or skeletal?
In some people, the problem lies only in the inclination of the teeth (dental). In others, the position of the bony structure is the determining factor (skeletal). To tell them apart, the clinical examination, the side-profile X-ray (cephalometry), the panoramic X-ray and digital records are assessed together. For general information on skeletal problems, see our page on skeletal jaw discrepancies.
Management in growing children
While growth continues, jaw development can be guided. This period can be an important opportunity for treatment planning.
- Class II: Options such as the Twin Block appliance, the Herbst appliance or headgear are considered. For a recessed lower jaw, you can also look at our page on lower jaw advancement.
- Class III: Approaches such as palatal expansion and a face mask can be used to support the development of the upper jaw. For details, see our pages on upper jaw retrusion and lower jaw protrusion.
In some adolescent Class II cases, the mandibular advancement feature found in clear aligners may also be suitable.
Management once growth is complete
- Camouflage treatment: The jaw position is not changed; the teeth are moved with braces or clear aligners, and with elastics and mini-screws if needed, so as to improve the fit of the bite. In some cases, tooth extraction may come up.
- Orthodontic treatment and jaw surgery: If the mismatch is pronounced, the teeth are prepared for surgery and the jaws are repositioned with an operation. For this method, you can read our article on orthognathic surgery.
Which path is chosen is determined by considering the facial profile, tooth and gum health, bone support and the person’s expectations together.
Do family and profile matter?
Class II and Class III tendencies can run in families. For this reason, if parents or siblings have a similar jaw structure, it may be helpful to monitor the child early. If the lower jaw looks clearly set back or forward in the side profile, this visible impression does not always mean a skeletal problem; the soft tissue structure also affects the profile. That is why the assessment is made with X-rays and measurements.
Why is the timing of treatment important?
- Before and during the growth spurt, appliances that guide jaw development can be used more effectively.
- After growth is complete, the method is mostly limited to tooth movement or surgery.
- In cases noticed early, treatment can be planned in two phases: first the fit of the jaws, then fine adjustment of the teeth.
Because the age at which the growth period ends varies from person to person, the clinician may assess development using a hand–wrist X-ray or the neck vertebrae.
After treatment
Whichever method is chosen, retention and regular check-ups are important to maintain the results. In skeletal problems, because of jaw growth or the tendency of the teeth to return to their former position, the check-up frequency recommended by the clinician should be followed. You can get information about other conditions on the all orthodontic problems page.
Having the first orthodontic check-up of children and adolescents at an early age makes it possible to monitor such differences during the growth period and to intervene in time if needed. For details, see our page on orthodontics for children.
Frequently asked questions
Do Class II or Class III problems correct themselves?
Skeletal mismatches generally do not correct themselves. Early assessment during the growth period helps in determining the options.
Can Class II or Class III be treated in adults?
Yes, though the methods are different. In mild and moderate cases orthodontic camouflage is considered, and in pronounced cases orthodontics together with jaw surgery is considered.
Is surgery needed in every Class II or Class III case?
No. In many people orthodontic treatment alone may be sufficient. Surgery generally comes up in cases where the jaw mismatch is pronounced and cannot be solved with the teeth alone.
How can you find out what suits you?
The information here is general; the right plan for you is determined by examination and clinical assessment. At our clinic in Oran, Çankaya, Ankara, we go through your questions together during the first orthodontic examination.
