This classification according to british standards institute classification:-
This class based upon incisor relationship and is the most widely used descriptive classification .
Class1-the lower incisor edges occlude with or lie immediately below the cingulum plateau of the upper central incisors.
Class2-the lower incisor edges lie posterior to the cingulum plateau of the upper incisors. There are two subdivisions of this category:
Division1-the upper central incisors are proclined or of average inclination and there is an increase in overjet.
Division2-the upper central incisors are retroclined. The overjet is usually minimal or may be increased.
Class3-the lower incisor edges lie anterior to the cingulum plateau of the upper incisors. The overjet is reduced or reversed.
Out line of management
The British Standards classification defines a Class2 division1 incisor relationship as follows: the lower incisor edges lie posterior to the cingulum plateau of the upper incisors, there is an increase in overjet and the upper central incisors are usually proclined.
In a Caucasian population the incidence of Class2 division1 incisor relationship is approximately 15-20 per cent.
Prominent upper incisors, particularly when the lips are incompetent, are at increased risk of being traumatized. It has been shown that children with an overjet greater than 9 mm are twice as likely to have suffered trauma involving their upper incisor teeth as are those with normal or reduced overjets.
The overjet is increased.
The upper incisors may be proclined.
Perhaps as the result of a habit or an adaptive swallow; or upright, with the increased overjet reflecting the skeletal pattern.
The overbite is often increased, but may be incomplete as a result of an adaptive tongue-forward sward swallow, a habit or increased vertical skeletal proportion.
The latter two factors are marked, an anterior open bite may result.
If the lips are grossly incompetent and are habitually apart at rest, drying of the gingivae may lead to an exacerbation of any pre-existing gingivitis .
The molar relationship usually reflects the skeletal pattern unless early deciduous tooth loss has resulted in mesial drift of the first permanent molars
Assessment of, and treatment planning
Factor should be considered before deciding upon a treatment plan:
1-The patient’s age.
2-The difficulty of treatment.
3-The likely stability of reduction.
4-The patient’s facial appearance.
Practical Treatment planning
In general class2 division1 malocclusions are commonly
with increased overbite, which must be reduced before the overjet
can be reduced.
Overbite reduction requires space (about 1-2 mm for an averagely
Significantly increased overbites will require more space and fixed
appliances, or even surgery.
If extraction are required in the lower arch, both spontaneous and
active tooth movement are facilitated by removal of the
tooth in the upper arch.
The actual choice of extraction site will depend upon the presence
crowding, the tooth movements planned, and their anchorage