An investigation on the cause of the removal of mandibular impacted third molar and its relationship with various types of impaction Dr. H. Mahmood Hashmei* - Dr. M. Seyed ashrafi** *- Associate Professor of Oral and Maxillofacial Surgery Dept. – Faculty of Dentistry – Tehran University of Medical Sciences. **- Dentist. Background and Aim: Impacted third molars, due to their extreme importance, have been paid attention by nearly most of dentistry disciplines. The causes of the removal of impacted third molars would be severe caries, TMJ pain, orthodontic treatments, crowding, pericoronitis, prosthetic treatments etc. The aim of the present study was to investigate the mentioned causes and to find out their relationship with different types of impaction. Materials and Methods: The causes of the removal of impacted third molars among 80 patients with the mean age of 25 years, 42 females and 38 males, referred the department of surgery, Dental Faculty, Tehran University of Medical Sciences were investigated. Panaoramic and periapical radiographs were studied and all selected subjects were finally confirmed by the professors of surgery department for the removal of mandibular impacted third molars. Results: The causes of the removal of mandibular impacted third molars were ranked as follows: prophylactic procedures (26.25%), pericoronitis (23.75%), severe pain (22.5%), pathologic condition (11.25%), orthodontic and crowding reasons (10%), TMJ pain (5%) and prosthetic treatments (1.25%). Types of impaction were observed sequentially as: mesioangular (43.75%), vertical (32.5%) and horizontal (18.75%). No inverted and unusuall types were observed. Conclusion: Pain, pericoronitis, prophylactic reasons and pathologic conditions were the most causes for the removal of mesioangular third molars. Pericoronitis and prophylactic reasons for the vertical type and pain along with prophylactic reasons for the horizontal type were mentioned as the most common causes. Key words: Impacted third molar – Mesioangular – Pericoronitis – Dentigerous cyst. | 
