Incidental Pathological Findings in Orthodontic Radiographs

A retrospective cross-sectional study was conducted using radiographs from 1 January 2015 to 31 December 2019. The study setting was the postgraduate clinic of the Department of Orthodontics at a university dental hospital. Utilizing all pretreatment panoramic radiographs as the sampling frame, systematic sampling was used to select a minimum of 100 radiographs. All panoramic radiographs were taken following a standard protocol with Orthophos XG3D/Ceph (Sirona Dental Systems, Germany) at an adjusted voltage of 60–90 Kv, and 3–16 mA, and an exposure time of 9.4–14.1 s. The Sirona protocol was adjusted to the patient’s age, size, and weight.
Sample size was calculated using a prevalence of 8.7% in incidental pathological findings in the orthodontic pre-treatment panoramic radiographs reported by Bondemark et al. [13 (link)]. A 95% confidence level and a precision of 5% in the prevalence estimate using the following Dobson’s formula [16 (link)] to give a minimum sample size of: $$n=\frac{Z^2\times p(1-p)}{d^2}$$
where $p$ is the prevalence of incidental pathological findings (8.7%);
$d$ is the precision of the estimate of prevalence of incidental findings (0.05);
$Z$ is the standard normal deviate at a given confidence level (1.96 at 95% confidence level).
Thus, using these input parameters, the minimum sample size was calculated to be

n = 100
The inclusion criteria were patient clinical records with no previous history of orthodontic treatment. The age group included adults and children and panoramic radiographs of good quality were used. Patients with previous history of orthodontic treatment and craniofacial anomalies were excluded from the study. Ethical approval was obtained from the Human Research Ethics Committee (M210625) to conduct the study.