Changes in the limit of the bone tissue strength of the mandible in its various parts at the loss of teeth in an adult

Traumatic injuries and fractures of the lower jaw are an urgent problem in maxillofacial surgery and traumatology. The strength of the bone tissue of the lower jaw has been studied on 90 lower jaws of adults. All jaws are systematized into three groups: with intact bite, partial and complete loss of teeth. To assess the architectonics of the bone tissue of the mandibular body, sagittal and frontal cuts were made in the molar region. It has been established that, in the case of a complete set of teeth, the ultimate strength of the bone tissue in the area of the incisors is 441.3 ± 32 MPa; in the area of premolars 411.9 ± 20 MPa; molars 431.3 ± 24 MPa; in the area of the base of the coronoid process 156.9 ± 14 MPa; in the area of the base of the condylar process 205.9 ± 19 MPa. To the greatest extent, with partial loss of teeth, the strength of bone tissue in the region of the molars and the angle of the lower jaw changes in Kennedy classes I and II. With the complete loss of teeth, the values of bone strength in the area of molars, angle and condylar process decreased by 22.527.7%, in the area of incisors by 6.7%. It was shown that with a full set of teeth, class II according to U. Lekholm and G. Zarb was most often observed - in 66.7% of cases, less often class I - in 16.7% and class III - in 13.3%, class IV was observed most rarely - in 3.3% of cases. With complete loss of teeth, the presence of mainly II and III classes is noted. It has been proven that the strength of the bone tissue of the lower jaw body decreases significantly with age with the loss of teeth in an adult, which is associated with significant changes in the quality of bone tissue.