PECULIARITIES OF FORMATION OF PATHOLOGICAL TOOTH WEAR FACETS AFTER FIRST MOLARS EXTRACTION

Kobylyak S. S., Lee Syaokun

CONTENTS

Scentific article

The article presents the results of study of the peculiarities of formation of tooth wear facets after first molars extraction, using method of occlusiography, among 40 patients aged 20-45 years. In the study of articulatory-occlusal relationships it has been revealed that 35. 7% of patients with absence of one molar have facets of increased tooth wear on the contacting surfaces of support cusps of premolars bordering defect of dentition. In 42. 9% of patients there are the signs of increased tooth wear of support cusps of posterior teeth on the opposite side of the defect, which indicated about the formation of one-sided type of chewing. In patients with loss of two first molars pathological tooth wear of separate groups has been detected in 41. 6% of cases. For bilateral removal of the first molars on one jaw it has been established increased wear of support cusps of premolars and cutting edge of the lower front teeth (75. 0% of the total number of patients with such a defect of dentition). In turn, the absence of the first molars from one side to the opposite jaw has been characterized by increased wear of premolars and canines on the side of defects and increased wear of the contacting surfaces of posterior teeth on the opposite side when a one-sided type of chewing has been formed (66. 7%). Under removing the first molars on opposite sides of opposing jaws it has been often detected wear of supporting cusps of premolars bordering defect of dentition, canines, cutting edge of lower anterior teeth (66. 7%). During examining of patients without three molars absence it has been found the following features functional overload. They are pathological tooth wear of supporting cusps of posterior teeth (in 57. 1% of cases), pathological tooth wear of canines (in 42. 8% of cases); pathological tooth wear of cutting edge of the lower and upper palatal surfaces of front teeth (in 28. 6% of cases). Also it has been found to increase the area of occlusal contacts on the support cusps of posterior teeth, the cutting edge of the lower and upper palatal surfaces of anterior teeth to form planar contacts. When examining of patients after removal of four first molars in 100% of cases it has been found a decrease in the height of central occlusion with reduced alveolar bone height in the side parts of the jaws and hypertrophy in the frontal area. Loss of four teeth leads to the formation of occlusal contacts on the premolars and front teeth mostly with planar character. While wear of contact surfaces of supporting cusps and cusps of canines are significantly expressed, especially in the lower jaw, it is widespread. It has been found that the general rule is increasing of the severity of tooth wear facets in direct proportion to the number of lost first molars. In the absence of the single sixth tooth, in the absence of two teeth on one side of the opposite jaw or in the absence of three teeth one-sided type of chewing usually forms on the opposite side of defect or on the side of one of the present sixth teeth. In the absence of three or four first molars a group function on the working side of the jaw often forms due to the significant canines wear. With increasing of number of extracted first molars it has been found the general tendency to wear of tubercles of premolars, canines, frontal teeth, indicating the distal shift of the mandible and transferring of the main chewing function on the teeth located in front of the de-fect. The increase in the occlusal contact plane on the teeth indicates that there are functional overload conditions. However tooth loss is just one of the factors leading to the development of pathological tooth wear. Examination of the other mechanisms of disease will form the whole understanding of its pathogenesis, which is necessary to develop the measures for early diagnosis, prevention and treatment in the early stages.

tooth wear, first molars, occlusiography

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