Development and validation of an occlusal cant index

Perception of laypersons, orthodontists, and oral and maxillofacial surgeons about the transverse occlusal plane

INTRODUCTION

Transverse occlusal plane (TOP) should be parallel to the true horizontal lines of the face (ie, the interpupillary line [IP] and commissural line [CL]). This study aimed to investigate the opinions of laypersons, orthodontists, and oral and maxillofacial surgeons about the impact of imbalanced IP and CL on facial attractiveness.

METHODS

We used a symmetrical face image as the reference. Then, using Photoshop software, we constructed the following 6 photographs: TOP roll relative to CL and IP (3° and 6°) with parallelism of CL and IP, CL roll relative to TOP and IP (3° and 6°) with parallelism of TOP and IP, TOP and CL roll relative to IP (3° and 6°). Consequently, the participants rated the photographs on the basis of their attractiveness. Kruskal-Wallis and Mann-Whitney U tests were used to compare the ratings.

RESULTS

One hundred thirty-one laypersons, 22 orthodontists, and 20 surgeons participated in this study. It was found that 51.1% of laypersons, 86.4% of orthodontists, and 70% of surgeons selected the reference photograph as the most beautiful, followed by the photograph with a 3° roll of CL relative to TOP, with parallelism of TOP and IP (29% of laypersons, 31.8% of orthodontists, and 35% of surgeons).

CONCLUSIONS

Most participants selected the reference photograph as the most beautiful and realized a roll in the horizontal planes up to 3°. The parallelism of the esthetic line of dentition relative to interpupillary is preferred over its parallelism relative to CL.

Criterion Validity of the Newly Developed Occlusal Cant Index

OBJECTIVES

To assess the criterion-related (concurrent) validity of the newly developed occlusal cant index (OCI).

MATERIALS AND METHODS

Four standardized posterior-anterior (PA) cephalometric radiographs of four patients were obtained at a 0° occlusal cant (OC) and manipulated to create various degrees of OC from 1° to 4° on the right and left sides, with a total of 36 PA images. The angle between the actual horizontal line and the occlusal plane was manually drawn on each PA radiographic image. The set of radiographic images was displayed to 36 orthodontists, who were asked to measure the drawn angle and apply the OCI to each PA radiographic image.

RESULTS

The overall criterion-related validity of the OCI was statistically significant among all grades.

CONCLUSION

The OCI is highly valid and recommended for clinical consideration.

Maxillary Sinus Volume in Patients with Canted Occlusal Plane: A Cone‐Beam Computed Tomography Study

OBJECTIVES

To compare the maxillary sinus volume between both sides in adult patients with upper occlusal canting (>2 mm cant) and a control group (≤2 mm cant) using cone-beam computed tomography scans.

MATERIALS AND METHODS

This retrospective study included a total of 84 scans (42 scans per group) according to predetermined selection criteria. OnDemand 3-D™ software was used for volumetric and linear measurements of the maxillary sinus. Maxillary occlusal canting was determined at the level of the maxillary first molars. It was defined as the vertical difference between right and left sides relative to the Frankfort horizontal plane. Non-parametric tests were applied.

RESULTS

The median difference in the maxillary sinus volume between the sides was statistically significant between the control and cant groups (P < 0.001). Also, the median difference in the maxillary sinus craniocaudal height and apex sinus distance between the sides was statistically significant between the control and cant groups (P < 0.05 and P < 0.001, respectively).

CONCLUSION

In adult patients, maxillary occlusal canting of more than 2 mm was associated with asymmetric maxillary sinus volumes. In the cant group, maxillary first molars on the canted-down side were in close proximity to the sinus floor, which suggests a limited leeway for molar intrusion.