Original article
Reliability and validity of mandibular posterior vertical asymmetry index in panoramic radiography compared with cone-beam computed tomography

https://doi.org/10.1016/j.ajodo.2017.08.019Get rights and content

Highlights

  • Even in CBCT images, condylar height 1 shows low reliability.

  • For detecting asymmetry of the condyle region, it is recommended to use CBCT.

  • Asymmetry index of total ramal height showed good reliability and validity.

Introduction

The purposes of this study were to compare the asymmetry index using panoramic radiography and cone-beam computed tomography for detecting mandibular posterior asymmetry and to evaluate the diagnostic value of the asymmetry index on panoramic radiography.

Methods

A total of 43 patients were included in this study. Ten mandibular posterior distances were measured using panoramic radiography and cone-beam computed tomography, and 10 asymmetry index values were calculated. The reliability of each asymmetry index was assessed. For evaluating validity of each asymmetry index using panoramic radiography, the paired t test and the Bland-Altman analysis were used. The accuracy of the asymmetry index and the area under the curve of receiver operator characteristic were calculated.

Results

The asymmetry index of total ramal height showed good reliability (ICC, >0.888). In condylar height 1, specificity and negative predictive value were low (0.08 and 0.17, respectively), 95% limits of agreement were ±17.9%, and area under the curve was 0.484. In total, ramal height accuracy was 0.86, and areas under the curve were 0.926 to 0.957.

Conclusions

For detecting asymmetry of the condyle region, the asymmetry index using panoramic radiography had little diagnostic value, and we recommend using cone-beam computed tomography images. However, the asymmetry index for total ramal height showed good reliability and relatively higher validity, and its diagnostic value was excellent.

Section snippets

Material and methods

For sample size calculation, a pilot test was executed with 20 patients who visited the Department of Orthodontics of Dankook University Dental Hospital in Cheonan, South Korea. To achieve power of at least 80% using the paired t test with a significance level of 0.05 and using effect sizes calculated from differences (mean, 0.342; pooled standard deviation, 0.780), at least 43 patients were needed. Those who had syndromic disease (eg, cleft lip and palate) and those with a history of

Results

Table I shows the ICC values, the Dahlberg33 values for the asymmetry index on the panoramic radiography and CBCT, and agreement between CBCT measurements. When CBCT was used, reliability of asymmetry indexes was good (ICC, >0.853). However, ranges of the 95% limits of agreement in condylar height 1 and ramal height 1 showed relatively greater values than the rest of the measurements. For all vertical variables, CBCT was more reliable than panoramic radiography. When panoramic radiographs were

Discussion

Accurate diagnosis of asymmetry in the mandibular facial region is important for both orthodontists and patients for establishing adequate treatment plans and to obtain the best treatment outcomes. For detecting mandibular posterior asymmetry, in many studies,15, 16, 17, 18, 19, 20, 21, 22 panoramic radiography was used with a formula for the asymmetry index.15 By the development of radiologic technology, the effective dose for CBCT can be decreased by limiting the field to structures of

Conclusions

The asymmetry index value for condylar height 1 was noninformative and showed lower reliability and validity than did that of condylar height 2. The asymmetry index of ramal height 1 showed lower reliability and validity than did that of ramal height 2. Although the asymmetry indexes of condylar height 2 and ramal height 2 were used, their accuracies were 0.47 and 0.85, respectively. Therefore, one should use caution when detecting asymmetry of condylar and ramal heights using only panoramic

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