Open Journal of Stomatology, 2017, 7, 186-196 http://www.scirp.org/journal/ojst ISSN Online: 2160-8717 ISSN Print: 2160-8709 A Comparison between 2D and 3D Images to Study Maxillary and Mandibular Widths: A Pilot Study Ilaf Al Mawaldi1*, Sawsan Tabbaa2, C. Brian Preston3, Mayssa Salti4 1Department of Orthodontics, School of Dental Medicine, SUNY at Buffalo, New York, USA 2School of Orthodontics, Brooks Rehabilitation College of Healthcare, Jacksonville University, Florida, USA 3Department of Orthodontics, School of Dental Medicine, SUNY at Buffalo, New York, USA 4Post-Graduate Program, Department of Orthodontics, School of Dental Medicine, SUNY at Buffalo, New York, USA How to cite this paper: Al Mawaldi, I., Abstract Tabbaa, S., Preston, C.B. and Salti, M. (2017) A Comparison between 2D and 3D The objective of this study is to compare the transverse dimensions of the Images to Study Maxillary and Mandibular jaws, obtained from traditional posteroanterior (PA) cephalometric radio- Widths: A Pilot Study. Open Journal of graphs, and with the similar respective measurements obtained by means of Stomatology, 7, 186-196. cone beam computed tomography (CBCT). Data of twelve subjects were se- https://doi.org/10.4236/ojst.2017.73014 lected from the clinical records of Orthodontic Department. All of the subjects Received: February 16, 2017 had their permanent teeth in occlusion and had good quality regular (2D), Accepted: March 28, 2017 and CBCT (3D) images as part of their initial records. Subjects were divided Published: March 31, 2017 to a posterior cross-bite and non-cross bite groups. The ratio of the maxillary, Copyright © 2017 by authors and to mandibular transverse widths was calculated for the sample. In subjects Scientific Research Publishing Inc. without dental cross-bites the average ratio of the maxillary, to mandibular This work is licensed under the Creative jaw widths was 0.75 on the standard radiographs and 1.04 on the CBCT scans. Commons Attribution International In subjects with dental cross-bites the average ratio of these widths was 0.70 License (CC BY 4.0). http://creativecommons.org/licenses/by/4.0/ on the standard radiographs and 0.9 on the CBCT scans. The ratios of the Open Access maxillary, to mandibular widths differ when obtained from conventional ce- phalometric radiographs as compared to the respective ratios obtained from CBCT scans. Maxillary, to mandibular width ratio is in the order of 1:1 as de- termined by means of CBCT scans. Keywords Posteroanterior Cephalometric (PA) Radiograph, CBCT, 2D, 3D, Transverse Jaw Measurements, Posterior Cross-Bite 1. Introduction Although orthodontists tend to rely on lateral and anteroposterior cephalome- DOI: 10.4236/ojst.2017.73014 March 31, 2017 I. Al Mawaldi et al. tric radiographs to determine the existence, and degree, of craniofacial abnor- mality that is present in their patients, several limitations are inherent in the use of these means of records in a clinical setting. Such limitations are frequently linked to the fact that it can be more or less impossible to identify, with the re- quired accuracy, many of the landmarks that constitute a particular cephalome- tric analysis [1]-[11]. During the past decade CBCT, which has evolved from medical computed tomography [12] has become a part of the diagnostic methods that are available to orthodontists. There is the expectancy that these new developments may eliminate some of the shortcomings that are associated with conventional radio- graphs of the facial region [9]. The accuracy and reliability of CBCT images have been tested and were found to be adequate for implant planning, periodontal disease quantification, and assessment of the volumes of tumors. Moreover, the reconstructed CBCT images are accurate and reliable when compared with the respective conventional radiographs of the same region. Commercially available software makes it possible to take full advantage of CT scans in performing 3D measurements and in developing 3D craniofacial analyses [13]. For this, and other reasons, a trend has developed to change from traditional 2D analog films to 3D digital imaging systems. Transverse problems, such as posterior cross-bite, are a great concern to or- thodontists and have been mentioned as having very real potential for relapse [7]. In addition, posterior cross-bites CBs have been reported to be represented in most of prevalent malocclusions of the primary dentition in White children and there is the possibility that, if left untreated, cross-bites may lead to cra- niofacial asymmetry [14]. As unilateral cross bite commonly arises as a result of a relatively narrow maxilla, the relationship between the widths of maxillary and mandibular skeletal bases is presumably the most critical information sought from the PA cephalometric record [14] [15]. In order to identify, and quantify skeletal discrepancies and facial asymmetries there have been attempts to develop cephalometric analyses applicable to the transverse craniofacial measurements [7] [14] [16]. Thus, the presence of a small maxillary to mandibular skeletal width ratio could indicate the existence of a skeletal component in the presence of a dental cross-bite. This finding could have important clinical implications regarding early verses late treatment. On the other hand, if the review of the records reveals a larger than or normal ratio, the posterior cross-bite would be more likely of a dental nature [8] [14] [17]. But then studies [2] pointing to the inherent limitations of two dimensional techniques that are used currently to determine facial asymmetry arise the chal- lenge that faces orthodontics to understand, and reconcile, two dimensional ce- phalometric measurements with the volumetric environment of CBCT scans. The selection of anatomical landmarks used in three dimensional cephalometric analyses tends to follow the definitions that apply to the respective anatomical landmarks used in conventional cephalometric analyses [11]. Recently Andrews described an anatomic ridge on the mandibular alveolar 187 I. Al Mawaldi et al. process that corresponds in position to a soft-tissue band that is usually located immediately superior to the mucogingival junction [17]. This soft-tissue struc- ture was called the WALA ridge after Will, and Larry Andrews who jointly pro- posed this ridge, although being present in both jaws, as a reference line for de- termining the morphology of the mandibular dental arch. The WALA ridge ap- proximates the supero-inferior position of the centers of rotation of the mandi- bular teeth and it has been suggested that this anatomical feature presents a use- ful guide as to the appropriate width of the mandibular basal bone [18]. The WALA ridge is easy to identify on CBCT scans oriented in the coronal plane of the skull and it may prove useful in determinations of the required jaw widths for orthodontic patients. The purpose of the present pilot study was to compare the transverse mea- surements of the mandibular and maxillary jaws as obtained from conventional PA cephalometric radiographs with the respective corresponding measurements obtained by cone beam computer tomography CBCT. 2. Materials and Methods The records of twelve subjects were included in this pilot study. The subjects in- cluded in this study were the first twelve patients who had complete initial records of sufficient quality to allow for the required measurements to be made. Informed consents were obtained from all patients. The appropriate records in- cluded posteroanterior 2D radiographs of suitable quality, CBCT scans of the craniofacial structures and study models. Study models were used to determine the presence or absence of posterior crossbites in addition to clinical examina- tion. The subjects included in this investigation had all of their permanent teeth in an occlusion up to, and including, their first permanent molars. Patients with missing permanent molar teeth, with craniofacial deformities and with PA radi- ographs with indications that their head may have been misaligned during ex- posure of the radiograph were excluded from this study. Seven of the twelve subjects selected for this study had good posterior dental over jet and these pa- tients formed a subgroup of non-posterior cross-bite patients. The remaining five patients included in this study had study models that demonstrated the presence of posterior cross bites. The presence of posterior cross bite was de- fined as a minimum of two teeth in unilateral or bilateral lingual cross bite or edge to edge cusps, based upon plaster or Ortho-cadTM models and clinical eval- uation. Cephalograms were traced and measured by hand, and all measurements were made by a single investigator (I.M). The enlargement factor for the cepha- lometric radiographs was calculated at 8%. Landmarks (JR, JL, AgR, AgL) and measurements (JL-JR, Rag-LAg) to assess transverse discrepancies between the maxilla and the mandible were chosen according Ricketts PA cephalometric analysis [16] [19] [20]. To assess skeletal constriction, the ratio (JL-JR/Rag-LAg) between the maxillary and mandibular widths was computed (Norm JL-JR/ RAg-LAg = 80%) [20] (Figure 1). The CBCT scans used in this study were obtained by means of an I-CatTM 188 I. Al Mawaldi et al. Figure 1. Posteroanterior (PA) cephalometric landmarks used in the study (J, Ag). scanner (Imaging Sciences International, Inc., Hatfield, PA, USA). The field size was set at 8 cm ad the voxel size at 0.4 mm. The resultant DICOM data were manipulated with the software