The Reserch of Relationship Between the Largest Circumference of Crowns,Cusps and Roots of the Maxillary Third Molar Tooth

Objective To understand the types of roots by the latest circumference of crowns and the types of cusps of the maxillary third molar tooth. Methods The largest ciucumference of crowns, types of cusps and types of roots of 100 extracted maxillary third molar tooth were observed and summed up by forms, and then statisticaly treated. Results 1. The average value of the largest circumference of crowns of the maxillary third molar tooth was 32.21mm.3 cusps(48%) was more than others. 1 root was more then others.2.The main fact to influence the types of roots of Maxillary third molar was the largest circumference of crown, not the types of cusps. The relationship between the types of cusps and the types of roots was indirect contact. Conclusion Clinically we can infer the types of roots by the largest circumference of crowns of the maxillary third molar and by consulting the types of cusps.