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Fig. 1 | Head & Face Medicine

Fig. 1

From: Comprehensive analysis of ectopic mandibular third molar: a rare clinical entity revisited

Fig. 1

Definition and classification of ectopic mandibular third molar based on panoramic images. a: diagram describing the definition and classification of ectopic mandibular third molar based on panoramic images. The line a was drawn from the occlusal plane of the mesial teeth such as the second and/or first molar. The intersection point between the line a and anterior mandibular ramus was defined as AMR (anterior mandibular ramus). The line b was extended from the root tips of the second molar or first molar when second molar was absent, which was also in parallel to the line a. The line c was perpendicular to line a and tangential through the distant contour of the mesial tooth. The line d was through the AMR point and parallel to the line c. Thus, the area surrounded by the four lines was defined as the physiological region (marked as the yellow area) for the third molar eruption. Therefore, four levels (I-IV) were defined as ectopic locations for the mandibular third molar. b: Any parts of the third molar which fall into the putative normal region as marked as the yellow area or contact with this area were defined as impaction rather than ectopic and excluded here. c-f: representative images of level I-IV ectopic third molar in mandible

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