Page 50 - Open versus closed Mandibular condyle fractures

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Chapter 2.2 Closed
Measurements
The treatment result of case 4 was evaluated. The pre-treatment CT and post- treatment CBCT were exported in DICOM format and subsequently imported into Maxilim (Medicim NV, Mechelen, Belgium). In Maxilim, a hard-tissue reconstruction was generated from the DICOM data. A reference frame was set up for the CT scan.9 A voxel-based matching algorithm was used to superimpose the post- treatment CBCT scan on the pre-treatment CT scan in the reference frame.10 Two different matches were generated: one for superimposition of the cranium and one for superimposition of the mandible.
Landmarks were indicated on the coronal slices of the CT and matched CBCT scan on the mesiobuccal cusps of the premolars and molars of the maxilla. Similarly, in the mandible, the mesiolingual cusps of the premolars and molars were identified. The identification of the landmarks was performed twice to assess the influence of intra-observer variability and measurement error on the result. The difference in position of the landmarks pre-treatment and post-treatment was calculated in craniocaudal direction to identify if axial tooth movement had occurred.
Results of the measurements
The mean intra-observer difference between the indicated landmarks of the two measurements was 0.15 ± 0.12 mm. In table 2, the mean difference between pre-treatment and post-treatment is provided for all premolars and molars in the craniocaudal direction. It appears that there is a slight tendency for dental intrusion, this was equally apparent for both the upper and lower dentition. There was no axial tooth movement sufficient enough to explain the correction of the bite.