Three-Dimensional Changes of the Auditory Canal in a Three-Year Period during Adolescence Using CBCTs.

Adam Woods,Manuel O Lagravère

doi:10.1155/2018/5463753

Abstract

Purpose There is a lack of identifying suitable regions in the head that can be used for three-dimensional superimposition techniques. For this reason, with the use of cone-beam computed tomography (CBCT), the ear canals were analyzed to verify changes during a period of three years in the adolescent years. Methods CBCTs from fifty-six patients (ages: 10 to 20) were used to landmark the anatomy of the ear canals. Each patient was analyzed using two CBCT reconstructions that were taken approximately three years apart. AVIZO® software was used to locate 28 landmarks distributed following the ear canal path and foramina (ovale, spinosum, rotundum, etc.) in the cranial base to obtain spatial relationships. Three-dimensional coordinates were obtained from the landmarks, and the average distance between various landmark pairings was calculated. The repeated measure ANCOVA was used to determine statistical significance. Results In the main data set, the largest mean distance change was found to be 4.37 mm ± 18.29 mm between the left foramen ovale and the left superior medial ear canal opening. The smallest mean distance change was 0.18 mm ± 3.25 mm between the right inferior lateral ear canal opening and the right inferior medial ear canal opening. Conclusions During the adolescent years, the ear canal presents dimensional changes. Even though in different areas throughout the canal, the average distances were minor, still, large standard deviations were present; thus, caution should be taken when trying to use this structure for superimposition of CBCTs.

Highlights

Cone-beam computed tomography (CBCT) has become a popular imaging tool for dental practitioners in North America to visualize structures in the head and neck in three dimensions (3D)
While CBCTs struggle with the differentiation of very similar density soft-tissue structures, they produce a high-resolution image when compared to 2D imaging at a lower cost and lower radiation dose when compared to medical CT [1]. e 3D capabilities of CBCTs allow clinicians to better understand a patient’s dental development, the potential for dental movement, and possible airway obstruction
In order to ensure reliability of the landmarks chosen, the CBCTs of ten patients were landmarked three times, with one week in between each landmarking session. e largest measurement error was found in the Z-coordinates of the left ear canal lateral opening posterior landmark (Figure 1) at 2.0 mm. e smallest measurement error was found in the Z-coordinates of the crista galli landmark at 0.1 mm

Summary

Introduction

Cone-beam computed tomography (CBCT) has become a popular imaging tool for dental practitioners in North America to visualize structures in the head and neck in three dimensions (3D). E 3D capabilities of CBCTs allow clinicians to better understand a patient’s dental development, the potential for dental movement, and possible airway obstruction. CBCTs have become useful in orthodontic treatment, allowing practitioners to monitor treatment efficacy [2]. Of particular interest are the advantages that CBCTs offer practitioners when trying to superimpose facial structures to assess treatment outcomes. The potential for cephalometric analysis and diagnosis is promising as we move towards the 3D capabilities of CBCT [4]. Various authors have developed methods of reducing error associated with superimposition of structures using CBCT, most typically using landmarks such as the left and right auditory meatus, the left and right infraorbitale, the left and right

Methods

Results

Discussion

Conclusion