Survey of the Condition of Each Tooth in Patients With Mandibular Protrusion by Age Group

Jaw deformities are known to cause occlusal collapse. However, the process of occlusal collapse is not clear. This study evaluated the dental health status of each tooth in patients with mandibular protrusion by age group to determine which teeth are affected by mandibular protrusion and clarify the progression of occlusal collapse.

This study evaluated the condition of each tooth in 113 patients with mandibular protrusion at the Orthodontic Department of Hokkaido University Hospital from 2013 to 2017 by age group. Patients were examined for decayed, missing, filled, and root canal-treated teeth. Filled teeth were classified into teeth with filling composite resin and inlay (Filled tooth), teeth with attached crown (Crown tooth), and abutment teeth of bridge by treatment methods.

The Decayed, Missing, and Filled Teeth (DMFT) index for mandibular protrusion patients for 10s, 20s, 30s, 40s, 50s, and 60s was 5.3, 10.2, 14.8, 19.3, 19.8, and 18.7, respectively, which was higher in all age groups than in the results of the 2016 Survey of Dental Diseases in Japan. The survival rates of the lower molar tended to be low. The Filled tooth rate tended to be higher for molars than for other teeth for all ages. The Crown and abutment tooth rate increased in various teeth in the maxilla. In the mandible, the Crown tooth rate in the premolar and molar greatly increased, and the abutment tooth wasn't found in the incisor. The root canal-treated tooth rate was higher in the molar with increasing age in the mandible.

The findings raised the possibility that patients with mandibular protrusion may be more susceptible to some oral diseases, such as caries, periodontal disease, and occlusal trauma, and the condition of the molar region may tend to deteriorate compared to other regions.