Case-control study on self-reported osteoporotic fractures and mandibular cortical bone.

OBJECTIVES

The purpose of this case-control study was to determine whether the radiographic appearance of the mandibular cortical bone in patients who were elderly and noninstitutionalized was related to a self-reported history of osteoporotic fractures.

STUDY

DESIGN

Patients who had a billing statement at the School of Dentistry dated between 1993 and 1996, who were older than 60, and who had a panoramic radiograph were invited to be interviewed regarding fracture history (circumstances and year of fracture) and risk factors for osteoporosis. Cases (n = 93) were individuals reporting osteoporotic fractures (fractures occurring after minor impact). Controls (n = 394) were individuals reporting traumatic fractures (n = 105) or no fractures (n = 289). Blinded to case-control status, we evaluated the mandibular cortex on a panoramic radiograph and classified them as normal (even and sharp endosteal margin), moderately eroded (evidence of lacunar resorption or endosteal cortical residues), or severely eroded (unequivocal porosity). In addition, cortical thickness was measured below the mental foramen.

RESULTS

After adjustment for potentially confounding factors, the odds ratio for an osteoporotic fracture associated with moderately eroded and severely eroded mandibular cortices was 2.0 (95% CI, 1.2 to 3.3) and 8.0 (95% CI, 2.0 to 28.9), respectively. After adjusting for all potentially confounding factors, we found that the cortex was 0.54 mm (or 12%) thinner in subjects with an osteoporotic fracture compared with controls (95% CI, 0.25 to 0.84 mm).

CONCLUSIONS

Subjects with a self-reported history of osteoporotic fractures tend to have increased resorption and thinning of the mandibular lower cortex.