Determining Orbit Changes in Vertical and Non-Vertical Growing Adolescents

Objectives: Determine three-dimensional spatial and skeletal orbit changes between adolescents previously grouped as vertical and non-vertical growers overtime by cone-beam computed tomography (CBCT).
Methods: The study sample was taken from thirty-six patients from the ages of 11-17 years. Sixteen patients were categorized as vertical growers and twenty were categorized as non-vertical growers. Patients had two to three CBCTs taken with a time interval between of 19-24 months. The analysis of the CBCT datasets was completed using the third-party software Avizo. Sixteen distinct anatomical landmarks resulting in 24 distances were used to measure transverse, antero-posterior and vertical spatial and structural changes of both orbits. Reliability (Intraclass Correlation Coefficient – ICC) and measurement error of all landmarks were calculated using ten CBCTs landmarked three times. Descriptive statistics and t-test statistical analyses were used to determine the overall changes in the orbits.
Results: All landmarks show an excellent reliability with the largest measurement error being the Y-coordinate of the left most medial point of temporalis grooves at 0.95mm. All ICC values were excellent with the lowest being from the right most antero-inferior point of the superior orbital rim with an ICC value of 0.99. For the vertical grower subgroup, the largest mean difference of 1.6646mm was obtained from the right most antero-medial zygomatic bone to right medial temporalis grooves. For the non-vertical grower subgroup, the largest mean difference was 5.062mm which was from right to left most antero-inferior superior orbital rim. The mean transverse, antero-posterior and vertical differences for the vertical subgroup were 0.2368mm, 0.1909mm and 1.2810mm respectively. For the non-vertical subgroup, the mean differences were 0.7824mm, 0.4731mm and 0.5095mm respectively.
Conclusions: There were no significant skeletal or spatial changes in the period of 19-24 months between the vertical and non-vertical grower subgroups which consisted of sixteen and twenty patients respectively.