Skeletal Fluorosis: A Risk Factor of Bone Fractures Among Adults in Ethiopia: A Case-Control Study

Abstract

Background: Fluoride is a beneficial trace element. It is contained in the calcified tissues. Fluoride has a prophylactic effect against dental caries when absorbed in doses of less than 1.5 mg/day on the surface of the tooth enamel. It is also used as a therapeutic agent in adults for the treatment of postmenopausal osteoporosis at doses of 15 to 25 mg/day. However, fluoride in high doses can cause skeletal fluorosis, which can lead to bone fractures. The effects of fluoridated water on the skeleton are poorly understood, but there is some evidence that prolonged consumption of highly fluoridated water increases the risk of bone fractures. This case-control study examined the association between skeletal fluorosis and bone fractures among adults living in Ethiopia's Rift Valley (fluoride endemic) region. Method: A case-control study was conducted among adult Ethiopians in February 2023 to investigate the association between skeletal fluorosis and bone fractures. The study aimed to determine whether skeletal fluorosis poses a risk for bone fractures. Three matched controls were chosen for every case, considering a 1:3 ratio. Spine radiographic investigations were conducted to determine possible skeletal fluorosis-associated morphologic changes among the study participants. Chi-square tests and odds ratios (ORs) were computed. The P-value was also calculated considering a degree of freedom (df) of 1. Results: Given the 1:3 ratio between cases and controls, the study included 9 cases (6 females and three males) and 27 controls. The cases were diagnosed with femoral neck fractures (n=2), callus fractures (n=2), distal tibial fracture (n=1), lumbar vertebra fractures (n=3), and calcaneal fractures (n=1). The age range of cases and controls was 38 to 69 years. Analysis revealed a statistically (p-value = 0.01) significant association between skeletal fluorosis and bone fractures. Five subjects (4 cases and one control) had a constellation of abnormal bony changes in the spine. The odd ratio (OD) and chi-square (χ2) were calculated as 20.80 and 6.27, respectively, while the 95% CI was determined as [1.904, 227.274]. Conclusion: This study revealed that skeletal fluorosis is a risk factor for multiple types of bone fractures among adults living in a highly fluoridated area in Ethiopia. However, more thorough studies need to be conducted with a broader study population to further determine the association between skeletal fluorosis and bone fractures.