Minimum size and positioning of imaging field for CBCT scans of impacted maxillary canines

Abstract

Objectives In children and adolescents, cone-beam computed tomography (CBCT) is frequently used for localization of unerupted or impacted teeth in the anterior maxilla. CBCT causes a higher radiation dose than conventional intraoral and panoramic imaging. The objective was to analyze the location of impacted canines in a three-dimensional coordinate and thereby optimize the CBCT field-of-view (FOV), for radiation dose reduction. Materials and methods Location of 50 impacted maxillary canines of children under 17 years was retrospectively evaluated from CBCT scans. The minimum and maximum distances of any part of the right-and left-side canines to three anatomic reference planes were measured to assess the adequate size and position of a cylindrical image volume. Results A cylinder sized 39.0 (diameter) × 33.2 (height) mm, with its top situated 13.8 mm above the hard palate, its medial edge 8.4 mm across the midline, and anterior edge 2.5 mm in front of the labial surface of maxillary central incisors fitted all the analyzed canines. Conclusions In this sample, the FOV required for imaging maxillary impacted canines was smaller than the smallest FOV offered by common CBCT devices. We encourage development of indication-specific CBCT imaging programs and aids to facilitate optimum patient positioning. Clinical relevance An impacted maxillary canine is a common dental problem and a frequent indication for 3D imaging particularly in growing individuals. This article focuses on the optimization of CBCT of impacted canines. Our recommendation of a reduced FOV promotes radiation safety.

Minimum size and positioning of imaging field for CBCT-scans of impacted lower third molars: a retrospective study

“…The present study was carried out to define a minimum FOV size and optimal positioning for CBCT-imaging of lower third molars. The need for guidelines of indication-specific optimization for CBCT-scans has been emphasized in previous studies [ 13 , 15 , 19 ], but, to our best knowledge, minimum FOV size with adequate positioning protocol based on exact 3D location of a tooth has been defined only for impacted maxillary canines [ 19 ]. In the present study, the minimum FOV and optimum positioning for imaging of lower third molar were defined according to exact 3D locations of 50 third molar teeth, showing a representative variety of vertical, horizontal, distoangular and mesioangular inclinations and full length of root development.…”

“…Common standard small FOV sizes are 4 × 4 cm or 5 × 5 cm [ 10 ]. Previous studies on indication-specific FOV-sizes have recorded that small standard FOVs, or even smaller, present adequate diagnostic information [ 13 , 15 , 19 ]. Using specific indication-dependent optimization in case of tooth auto-transplantation in children, sufficient information from CBCT-examination has been achieved with FOV size 5 × 5 cm [ 13 ].…”

“…Using specific indication-dependent optimization in case of tooth auto-transplantation in children, sufficient information from CBCT-examination has been achieved with FOV size 5 × 5 cm [ 13 ]. For impacted maxillary canines, minimum FOV size with optimal positioning could be smaller than standard ones, 4 × 3.5 cm [ 19 ]. When comparing three different FOV sizes (3 × 4 cm, 4 × 4 cm and 6 × 6 cm) the largest FOV presented the lowest diagnostic level for implant planning, possibly due to scattered radiation, and, in contrast, the smallest FOV size the lowest diagnostic level for periapical diagnosis, 4 × 4 cm obtaining the best overall ranking [ 15 ].…”

“…Studies about optimization of exposure parameters in standard FOVs exist, but exact indication-specific imaging protocols with FOV adjustment are rare in the literature [ 4 , 13 , 15 ]. Recommendations on FOV size and optimal positioning have been published for imaging of impacted maxillary canines [ 19 ]. Defining the optimum FOV is a major requirement for indication-specific optimization with advanced CBCT-technology.…”

Surgical-Periodontal aspects in orthodontic traction of palatally displaced canines: a meta-analysis

“…The diagnosis of impaction is performed through clinical and radiographic examinations, in addition to determining the location, for correct planning and conduct of the treatment to be performed. [ 9 , 10 ] The prognosis of treatment depends on the position, angulation of the canine in relation to the adjacent teeth and the possibility of the presence of ankylosis [ 8 ]. Various treatment alternatives are considered, such as extraction of the canine and movement of the premolars to the position of the same; auto transplantation; prosthetic rehabilitation to obtain occlusal harmony or association of a surgical technique with orthodontic treatment to move the tooth to the line of occlusion [ 8 , 11 , 12 ].…”