Comparison of mandibular cortical thickness and QCT-derived bone mineral density (BMD) in survivors of childhood acute lymphoblastic leukemia: a retrospective study

Abstract

Objective: To examine whether panoramic radiograph-determined mandibular cortical thickness correlated with quantitative computed tomography-derived bone mineral density (BMD) in survivors of childhood acute lymphoblastic leukemia (ALL).

Methods: We identified patients treated for ALL at St. Jude Children's Research Hospital, seen in the After Completion of Therapy (ACT) Clinic between January of 2006 and January of 2014 who had QCT-derived BMD and panoramic radiographs obtained within 1 month of each other. Panoramic radiographs were independently scored by a pediatric radiologist, two pediatric dentists, and a general dentist using the Klemetti technique. We used the Spearman's rank correlation test and the multivariate regression model to investigate the effect of evaluator experience on results.

Results: The study cohort comprised 181 patients with 320 paired studies: 112 (62%) male, 112 (71%) were white. Median age at ALL diagnosis was 6.4 (range, 0-18.8) years. Median age at study was 11.9 (range, 3.3 to 29.4) years. The median average BMD was 154.6 (range, 0.73-256) mg/cc; median QCT Z-score (age and gender adjusted) was -0.875 (range, -5.04 to 3.2). We found very weak association between panoramic radiograph score and both QCT-BMD average (P = 0.53) and QCT Z-score (P = 0.39). Results were not influenced by level of reader experience.

Conclusions: The Klemetti technique of estimating BMD does not predict BMD deficits in children and young adult survivors of ALL, regardless of reviewer expertise. Alternative methods are needed whereby dental healthcare providers can identify and refer patients at risk for BMD deficits for detailed assessment and intervention.

Figure 1

Panoramic radiographs demonstrating the appearance of mandibular cortex for each of the panoramic radiograph scores. Figure 1a: Normal mandibular cortex (C1) Figure 1b: Mild to moderate mandibular cortical erosion (C2) Figure 1c: Severe mandibular cortical erosion (C3)

Figure 1

Panoramic radiographs demonstrating the appearance of mandibular cortex for each of the panoramic radiograph scores. Figure 1a: Normal mandibular cortex (C1) Figure 1b: Mild to moderate mandibular cortical erosion (C2) Figure 1c: Severe mandibular cortical erosion (C3)

Figure 2

Scatter plot comparing panoramic radiograph score and QCT