Abstract
As a result of serial observations of models collected of grade school children at an interval of 8 years with twice a year in which efforts were made to determine the incidence period of deep overbites and factors involved in their formation, the following findings are noteworthy.
1. No matter what causes are involved in the process, the majority of deep overbites occur when the patients are comparatively young, around 7 to 11 years.
2. It is found that the destruction and loss of deciduous molar crowns have much bearings upon the incidence of deep overbite and in the scope of the present study, nearly 80 % of cases are attributable to this cause.
3. The majority of deep overbite cases were found to suffer from the destruction and loss of deciduous molar crown both on their upper and lower jaws. When only one jaw is concerned, there is a strong tendency that deep overbite, when it exists, is due to the destruction and loss of molar crowns and is found on the lower jaw.
4. It may be considered that a strong tendency of deep overbite exists when there is found the destruction and loss of deciduous molar crowns bilaterally rather than unilaterally.
