Abstract The aim of this study was to investigate the different variables in mesio-vertically positioned impact- ed or erupted third molars in a group of volunteers in Turkey to determine the angular changes and levels of eruption radiographically using standardised panoramic radiographs. There were 213 volunteers with impacted and erupted third molars included in this study, most of whom were dental students. Standardised panoramic ra- diographs were taken from all the volunteers. The radio- graphic parameters included angulation of tooth, level of eruption, development of root, mesiodistal crown width, retromolar space, and gonial angle. Statistical analysis was done using the t-test for independent groups. It was found that the mesiodistal angulation of third molars was significantly greater while the retromolar space of third molars was significantly smaller in the impacted group (P<0.05). There was also a significant difference in retromolar space/third molar crown width ratio (P<0.05). Keywords Third molars · Prediction of impaction · Long-term follow-up · Panoramic radiograph Introduction The third molar operation is a common operation carried out routinely in oral surgery clinics. Mandibular third molars are the most frequently impacted teeth after the maxillary third molars [1, 7]. It has been previously re- ported that the early removal of impacted third molars was not realistic [14]. Third molars should be removed when they are associated with various pathological con- ditions such as pericoronitis, cystic lesions, tumours, dental caries, periodontitis, periapical infection, and root resorption of adjacent teeth [1]. Third molars may also cause an impact on arch crowding and stability of ortho- dontic treatment [11]. It has been estimated that 54% of the mandibular third molars are removed prophylactically without pre- senting any subjective symptoms [13]. Lopes et al. [8] reported that, in the United Kingdom, 30–50% of all re- ferred mandibular third molars are removed every year with no valid indications. To retain mandibular third mo- lars might be beneficial for both orthodontic and prosth- odontic treatment and also for transplantation [6]. Age at eruption of third molars varies between different races, being on average 14 years in Nigerians [10] but 24 years in both Greeks [4] and Jordanians [5]. It has been previ- ously reported that patterns of facial growth, jaw devel- opment and tooth size are inherited and differ between populations and races [6]. The aim of this study was to investigate the different variables in mesio-vertically positioned impacted or erupted third molars in a group of Turkish volunteers be- tween the ages of 17 and 26 to determine the angular changes and levels of eruption using standardised pan- oramic radiographs. Materials and methods In this study, 213 volunteers participated, including 125 male and 88 female patients with a total of 557 mandibu- lar third molars. All the volunteers had erupted or im- pacted mesio-vertically positioned unilateral or bilateral third molars. This study was carried out at the University of Gazi, Faculty of Dentistry, Department of Oral and Maxillofacial Surgery and Oral Radiology. The mean age of the patients was 22 (range 17–26), with a mean age of 20.2 in the impacted group and 23.9 in the erupted N. Mollaoglu ( ✉ ) · S. Çetiner Department of Oral and Maxillofacial Surgery, Dental Faculty, University of Gazi, Ankara, Turkey e-mail: nmollaoglu@hotmail.com Tel.: +90-312-2126220/245, Fax: +90-312-2239226 K. Güngör Department of Oral Diagnosis and Radiology, Dental Faculty, University of Gazi, Ankara, Turkey N. Mollaoglu Bestekar sok. no. 61/8, Orta giris, 06680, Kavaklidere-Ankara, Turkey Clin Oral Invest (2002) 6:109–113 DOI 10.1007/s00784-001-0144-1 ORIGINAL ARTICLE Nur Mollaoglu · Sedat Çetiner · Kahraman Güngör Patterns of third molar impaction in a group of volunteers in Turkey Received: 18 June 2001 / Accepted: 22 October 2001 / Published online: 28 November 2001 © Springer-Verlag 2001