THE INFLUENCE OF DENTAL FACTORS TO ERUPTION OF THE MANDIBULAR THIRD MOLAR / 解剖学报

ABSTRACT

An investigation of the eruption of the mandibular third molar and an analysis of the causes of their impaction and absence were made. On macroscopic and X-ray examination, the rate of the impaction and absence was 19.74％ and 28.95％. respectively.In the analysis of the causes of the impaction and the absence of mandibular third molars we found that besides the length of the region posterior to the second molar already reported, the frequency of crowded teeth in the normal and in the impacted group is higher than that in the absent group. The mediodistal diameters of the mandibular second molar and first molar, which in the normal group are bigger than those in the other groups, also influence the eruption of the mandibular molars.