Anterior loop of the mental nerve: a morphological and radiographic study Dusan V Kuzmanovic Alan GT Payne Jules A Kieser George J Dias Authors’ affiliations: Dusan V Kuzmanovic, Alan GT Payne, Department of Oral Rehabilitation, School of Dentistry, University of Otago, New Zealand Jules A Kieser, Department of Oral Sciences, School of Dentistry, University of Otago, New Zealand George J Dias, Department of Anatomy and Structural Biology, Medical School, University of Otago, New Zealand Correspondence to: Dr Alan GT Payne Department of Oral Rehabilitation School of Dentistry PO Box 647 University of Otago Dunedin New Zealand Fax þþ 64 3 479 5079 e-mail: alan.payne@stonebow.otago.ac.nz Key words: anterior loop of mental nerve, implant treatment planning, anatomical dissection, radiography Abstract: Treatment planning for dental implant patients is often complicated by the unknown extent of the anterior loop of the mental neurovascular bundle. The aim of this study was to determine the correlation between the visual interpretation of the panoramic radiographs and the anatomical dissection findings in a cadaveric sample. Panoramic radiographs of the 22 randomly selected coronally sectioned human head specimens were taken using the Scanora s (Soridex, Orinon Corporation Ltd, Helsinki, Finland) radiographic unit jaw panorama (Programme 001, magnification 1.3) and dental panorama (Programme 003, magnification 1.7) and interpreted by two calibrated observers. Bilateral anatomical dissection was then performed on all specimens. The anterior loop of the mental canal was only identified in six panoramic radiographs (27%) (range 0.5–3 mm). There was a significant positive correlation between both observers of the radiographs and between the two radiographic programmes used. Anatomical measurements of the anterior loop of the mental neurovascular bundle revealed its presence in eight dissected specimens (range 0.11– 3.31 mm; mean 1.20, ± 0.90). Fifty percent of the radiographically observed anterior loops of the mental canal were misinterpreted by observers with both radiographic programmes and 62% of the anatomically identified loops were not observed radiographically. Clinicians should not rely on panoramic radiographs for identifying the anterior loop of the mental nerve during implant treatment planning. However, a safe guideline of 4 mm, from the most anterior point of the mental foramen, is recommended for implant treatment planning, on the basis of our anatomical findings. Treatment concepts for the edentulous mandible using removable implant over- dentures or fixed implant bridges identify surgical requests for two to five inter- foraminal implants, regardless of super- structure design (Batenburg et al. 1998; Merickse-Stern et al. 2000). When two implants are used, for removable over- dentures, there is lack of consensus on the inter-abutment distance (12–35 mm) with variation within reports (Naert et al. 1997; Watson et al. 1997; Wright & Watson 1998; Naert et al. 1999; Payne & Solomons 2000). When three, four or five implants are used for fixed or removable prosthodontic solutions, the crucial position of the distal two implants is determined by the essential surgical reference point of the mental foramina, and particularly the extent of the anterior loop of the mental neurovas- cular bundle (Solar et al. 1994; Rosenquist 1996; Misch 1998). The cantilever length of the fixed implant bridge, distal to the last implant, is also dictated by, to a greater extent, the position of the distal implant closest to the mental foramen. Addition- ally, in partially dentate patients, who have lost mandibular premolar and molar teeth, the mental foramen and mental nerve or its anterior loop is also the critical surgical ISSN 0905-7161 Copyright r Blackwell Munksgaard 2003 Date: Accepted 24 June 2002 To cite this article: Kuzmanovic DV, Payne AGT, Kieser JA, Dias GJ. Anterior loop of the mental nerve: a morphological and radiographic study Clin. Oral Impl. Res. 14, 2003; 464–471 464