A Study on the Relationship between Enamel Projections seen on the Molars and Periodontal Diseases

Abstract

Various causes for the periodontal complaint are generally classified as twofold; systemic and local ones. Of local causes, there are known the deposition of dental plaque, dental calculi, microbial colony and inadequate prosthetic materials. On the other hand, moreover, such congenital morphological anomalies as the shape of dental crowns, excessively shallow oral vestibule and abnormal development of the lingual frenulum can constitute local causes. All of these causes are recognized as being responsible for the incidence of some kind of periodontal disease or other.
The enamel projection, which came to receive attention in recent years, has been studied so far concerning the length of enamel projection itself, size and classification of its incidence frequencies.
In the belief that there must exist intimate relationships between the enamel projection seen on the molar and molar suffering from a periodontal disease, on the one hand, and the former and the resorption of alveolar rim of jaw bone, on the other, the author carried out the present study.
For the study purpose, the author examined clinically the presence or absence of enamel projections directly in the mouth of patients diagnosed as suffering from some kind of periodontal disease and, where the direct observations of the periodontal teeth were not possible, the presenceof enamel projections was investigated on the teeth which were extracted from the periodontal patients. Additionally, a total sample of 552 upper and lower jaws was selected from the skull specimens and on the basis of these jaws, a fourfold classification was established concerning the presence or absence of enamel projections on the teeth planted in them and the degrees of resorption of alveolar rim, so that the incidence frequencies of each of 4 groups might be fully elucidated.
As a result, the following conclusions were reached.
1. In about 74% of 308 upper and lower molars which suffered from the periodontal disease, the incidence of enamel projections was confirmed.
2. In nearly 90% of the upper and lower molars planted in jaw bones whose alveolar rims gave evidence of resorption, the incidence of enamel projections was established.
3. The resorption of alveolar rims was observed in nearly 95% of the jaw alveolar specimens possessed of upper and lower molars, on which enamel projections were confirmed.
On the strength of the above findings, it is to be concluded that there exists an intimate relationship between the presence of enamel projections and periodontal diseases, and the former may be regarded as constituting a noteworthy local cause of the latter.