Evaluation of condylar morphology following orthognathic surgery on digital panoramic radiographs. Could methodology influence the range of "normality" in condylar changes?

OBJECTIVES: To evaluate the morphological condylar changes following orthognathic surgery by using a rapid and reliable computational method on panoramic radiographs. METHODS: Digital panoramic radiographs of 45 patients who underwent bilateral sagittal split osteotomy (alone or associated with a Le Fort I osteotomy) between 2007 and 2010 were analysed. Calculation of the area, perimeter and height of 90 condyles was performed by using a specific computational method. Measurements were taken before surgery (m1), 1 day after surgery (m2) and 1 year after surgery (m3). The evolution of each index was analysed using paired t-tests between measures before and 1 day after surgery (m1 - m2) and measures before and 1 year after surgery (m1 - m3). The changes in the condylar area, perimeter and height were examined using the Bland and Altman plotting method. RESULTS: There were no statistically significant changes in the mean condylar area, perimeter or height between m1 and m2 or between m1 and m3. The Bland and Altman plots for each index showed that a very limited number of condyles increased or decreased in area, perimeter and/or height outside the boundaries of the measurement error. Given the impossibility for a condyle to increase in size, these results are considered to represent the limits of the computational method used. CONCLUSIONS: This study demonstrated that there were no significant morphological condylar changes at the 1-year follow-up following surgery and that the range of normality in condylar changes could be influenced by the methodology used.

Reliability of computational measurement of the condyles on digital panoramic radiographs.

OBJECTIVE: The aim of this study was to evaluate the reliability of a computational method for assessing three condylar measurements on digital panoramic radiographs: condylar height, area and perimeter. METHODS: A computer calculation of the area, the perimeter and the height of 34 condyles was determined on digital panoramic radiographs taken from 17 patients. The test-retest precision of measurements calculation was estimated using an intraclass correlation coefficient (ICC) and Dahlberg's formula at 2 week intervals on the same radiograph to assess intraobserver precision and on two radiographs (RX1 and RX2) to assess the radiographic procedure precision. Changes between measurements on RX1 and RX2 were estimated using paired t-tests to detect systematic errors. RESULTS: Precision of all indices was very high when measurements were made on the same radiograph, thus confirming good reliability for the present computational measuring method. The precision was lower when two different radiographs were compared but was still within an acceptable range of tolerance. There were no statistically significant changes in condylar area, perimeter or height values between RX1 and RX2. CONCLUSIONS: This study has demonstrated that (1) the height of the condyle can be rapidly and reliably assessed using a specific computer system directly on digital panoramic radiographs; (2) although less reliable, area and perimeter can also be acceptably evaluated; and (3) this method has the potential for being routinely used to monitor changes in clinical follow-up as well as for research purposes.

[Post-traumatic orbital reconstruction comparing preformed versus non preformed titanium mesh plates]. / Reconstruction orbitaire post-traumatique par grilles en titane préformées versus non préformées.

AIM: We compared, clinically and radiologically, the accuracy and reliability of two types of titanium mesh plates used for orbital reconstruction. The first were non-preshaped mesh plates (NPMP) and the second were three-dimensionally preformed mesh plates (PMP). METHODS: Two groups were created, each including 15 patients treated with NPMP and the second formed by 15 patients treated with PMP. The volume of each orbit was computed from coronal CT-scans using the OsiriX medical imaging software (version 3.3.2, www.osirix-viewer.com). Measurements were done for both, healthy and reconstructed sides. The other studied parameters were: sex, age, fracture distribution, and complications (diplopia and enophthalmia). RESULTS: The orbital volume difference between the reconstructed and the healthy contralateral side was not statistically significant in either group (NPMP: p=0.991 PMP: p=0.200). The mean orbital volume of reconstructed orbits was not statistically significant in either group (NPMP: 21.76 cm(3) and PMP: 20.28 cm(3), p=0.441). DISCUSSION: There is no difference in orbital volume reconstructions measured by the OsiriX software between non-preshaped and three-dimensionally preformed titanium mesh plates.