3D Mapping of Safe and Danger Zones in the Maxilla and Mandible for the Placement of Intermaxillary Fixation Screws

Abstract

Intermaxillary (IMF) screws feature several advantages over other devices used for intermaxillary fixation, but using cone beam computed tomography (CBCT) scans to determine the safe and danger zones to place these devices for all patients can be expensive. This study aimed to determine the optimal interradicular and buccopalatal/buccolingual spaces for IMF screw placement in the maxilla and mandible. The CBCT volumetric data of 193 patients was used to generate transaxial slices between the second molar on the right to the second molar on the left in both arches. The mean interradicular and buccopalatal/buccolingual distances and standard deviation values were obtained at heights of 2, 5, 8 and 11 mm from the alveolar bone crest. An IMF screw with a diameter of 1.0 mm and length of 7 mm can be placed distal to the canines (2 - 11 mm from the alveolar crest) and less than 8 mm between the molars in the maxilla. In the mandible, the safest position is distal to the first premolar (more than 5 mm) and distal to the second premolar (more than 2 mm). There was a significant difference (p<0.05) between the right and left quadrants. The colour coding 3D template showed the safe and danger zones based on the mesiodistal, buccopalatal and buccolingual distances in the maxilla and mandible.The safest sites for IMF screw insertion in the maxilla were between the canines and first premolars and between the first and second molars. In the mandible, the safest sites were between the first and second premolars and between the second premolar and first molar. However, the IMF screw should not exceed 1.0 mm in diameter and 7 mm in length.

Drill‐related root injury caused by intraoperative intermaxillary fixation: an analysis of 1067 screw applications

“…The regional distribution of root hits is contrary to the recommendations of CBCT‐based anatomical studies, which have declared safe and danger zones. For example, the spaces between the first and second premolars and between the second premolar and the first molar in the lower jaw are labelled as safe zones , whereas most injuries in the current study were found in this area (see Table ).…”

A comparative randomized prospective clinical study on modified erich arch bar with conventional erich arch bar for maxillomandibular fixation

“…To correct minor discrepancies in occlusion, the arch bar was placed for 4 weeks to enable the postoperative traction. [ 9 10 ]…”

“…[ 11 ] At the time of arch bar removal, tooth vitality was checked using electronic pulp tester (Vitality Scanner™ 2006), a diagnostic tool traditionally used to determine the vitality of dental pulp preoperatively and postoperatively. [ 9 10 ] Oral hygiene was assessed using the Oral Hygiene Index-Simplified (OHI-S)[ 12 ] by examination of debris, stains, and calculus on specific surfaces of 6 index teeth that included the buccal and lingual surfaces of maxillary and mandibular molars and central incisors. [ 12 ] The Index values were calculated using the debris score and calculus score.…”

Three-dimensional evaluation of the location of the mandibular canal using cone-beam computed tomography for orthodontic anchorage devices

“…The present study used CBCT imaging to measure the shortest distance between the mandibular canal and the surface of the mandible at various heights. Several previous studies of OAD placement sites used CT images (21)(22)(23)(24)(25), and a cadaveric study confirmed the accuracy of such images (6). However, CT imaging, including CBCT, is regarded as an invasive examination because of the radiation exposure involved.…”