Comparison of Mesiodistal Root Angulation Measured from Conventional and CBCT Derived Panoramic Radiographs in Orthodontic Patients

Comparison of mesiodistal root angulation of teeth by conventional panoramic and cone beam computed tomography images - A cross-sectional study

INTRODUCTION

Accurate bracket positioning is required for proper root parallelism and for stable orthodontic treatment outcomes. This study aimed to determine the difference in mesiodistal root angulation of teeth measured on three radiographic images.

MATERIAL AND METHODS

A cross-sectional study was conducted using orthopantomogram (OPG), panoramic images of cone beam computed tomography (Pan-CBCT) and cone beam computed tomography (CBCT). An occlusal plane was constructed in OPG and Pan-CBCT for angular measurements. The axial and sagittal views were used for assessing the mesiodistal root angulation on CBCT. Mesiodistal root angulation differences among three radiographs were assessed using the Kruskal-Wallis test. Mann-Whitney U test was applied for pairwise comparison and multinomial logistic regression was used to determine the association of sexual dimorphism with the direction of root angulation.

RESULTS

On comparing the mesiodistal root angulation in degrees (DE) among all three groups, upper right (UR2) and left lateral incisors (UL2) were found to be statistically significant with P=0.033 and P=0.050 respectively. On pair-wise comparison, we found a statistically significant difference for upper right lateral incisor (UR2) between OPG and Pan-CBCT (P=0.045). Upper left lateral (UL2) (P=0.024) was significant in OPG and Pan-CBCT while upper left first molar (UL6) (P=0.043) in OPG and CBCT group. On comparing the sexual dimorphism in the direction of root angulation, females showed a greater tendency of mesial root angulation (5.62) times for upper right second premolar (UR5) as compared to males.

CONCLUSIONS

There were no significant difference in mesiodistal root angulation between panoramic CBCT and CBCT images. The angulation of the upper lateral incisors was found to be significant between OPG and panoramic CBCT images, whereas the angulation of the upper right lateral incisors and left first molars was significant between OPG and CBCT images. In terms on sexual dimorphism, females showed greater mesial angulation of teeth than males.

Comparison between the designed and achieved mesiodistal angulation of maxillary canines and posterior teeth and influencing factors: First premolar extraction treatment with clear aligners

INTRODUCTION

This study aimed to compare the designed and achieved mesiodistal angulation of maxillary canines and posterior teeth (MCPT) for first premolar extraction with clear aligner treatment and identify the main influencing factors for preventing MCPT tipping toward the extraction space.

METHODS

A total of 21 adults with first premolar extraction were recruited. The designed and achieved tooth movement of MCPT was measured by superimposing their respective pretreatment and posttreatment cone-beam computed tomography images and compared with the designed tooth movement in ClinCheck using the paired t test and scatter plot analysis. Influencing factors, including dental arch length change, canine distalization, and initial mesiodistal angulation, were analyzed using the linear mixed-effect model.

RESULTS

Designed distal crown tipping (second premolar, 10.73 ± 3.22°; first molar, 9.83 ± 3.60°; second molar, 7.18 ± 2.36°) significantly increased the distal inclination of the second premolar (2.50° ± 5.15°; P ＜0.001), first molar (1.07° ± 4.14°; P ＜0.001), and second (0.70° ± 3.78°; P ＜0.001). Furthermore, mesial tipping (8.59° ± 6.03°; P ＜0.001) achieved appropriate distal crown tipping of canines (-6.43° ± 5.04°; P ＜0.001). The implemented preliminary formulas showed that shortening of the dental arch length, the distance of canine distalization, and initial mesiodistal angulation were closely related to the antitipping design.

CONCLUSIONS

Designed distal crown tipping of posterior teeth and mesial crown tipping of canines might prevent unwanted crown tipping toward the extraction space during space closure. The proposed preliminary formula could guide antitipping designs in clear aligner treatment.

Cone-Beam Computed Tomography in Orthodontics

Unlike patients receiving implants or endodontic treatment, most orthodontic patients are children who are particularly sensitive to ionizing radiation. Cone-beam computed tomography (CBCT) carries risks and benefits in orthodontics. The principal risks and limitations include ionizing radiation, the presence of artifacts, higher cost, limited accessibility, and the need for additional training. However, this imaging modality has several recognized indications in orthodontics, such as the assessment of impacted and ectopic teeth, assessment of pharyngeal airway, assessment of mini-implant sites, evaluation of craniofacial abnormalities, evaluation of sinus anatomy or pathology, evaluation of root resorption, evaluation of the cortical bone plate, and orthognathic surgery planning and evaluation. CBCT is particularly justified when it brings a benefit to the patient or changes the outcome of the treatment when compared with conventional imaging techniques. Therefore, CBCT should be considered for clinical orthodontics for selected patients. Prescription of CBCT requires judicious and sound clinical judgment. The central question of this narrative review article is: when does CBCT add value to the practice of orthodontics? To answer this question, this article presents discussion on radiation dosage of CBCT and other imaging techniques used in orthodontics, limitations of CBCT in orthodontics, justifying the use of CBCT in orthodontics, and the benefits and evidence-based indications of CBCT in orthodontics. This review summarizes the central themes and topics in the literature regarding CBCT in orthodontics and presents ten orthodontic cases in which CBCT proved to be valuable.