Key Findings - Variability in Radiographic Appearance of Fluorosis:

1) Skeletal fluorosis has a variety of radiological manifestations, including osteosclerosis, osteomalacia, osteoporosis, and secondary hyperparathyroidism.

2) The reason for the variability in the appearance of skeletal fluorosis is not yet fully understood.

3) Some factors which are believed to explain some of the variability include: dose, nutrition, and area of skeleton impacted.

Excerpts from the Scientific Literature - Variability in Radiographic Appearance: (back to top)

"Skeletal fluorosis caused by endemic fluorine poisoning was once thought to result merely in osteosclerosis, causing marblelike changes. Later, various radiologic features were found, including osteosclerosis, osteomalacia, and osteoporosis. Although this disorder has a wide variety of appearances, little attention has been given to the spectrum of radiologic appearances... The pathogenesis of these diverse radiologic appearances remains unclear."
SOURCE: Wang Y, et al. (1994). Endemic fluorosis of the skeleton: radiographic features in 127 patients. American Journal of Roentgenology 162: 93-8.

"Typical descriptions of skeletal radiology in endemic fluorosis have emphasized osteosclerosis (especially of the spine), membranous and ligamentous calcification, and exostoses... Our study showed in addition a wide variety of radiological patterns: ...[T]he pelvis showed the appearance of both osteosclerosis and osteopenia. Osteosclerosis was present in the central area of the pelvis while the lateral part showed considerable osteopenia. Vertebral bodies showed an osteopenic central region bordered by a sclerotic zone at the vertebral margin."
SOURCE: Mithal A, et al. (1993). Radiological spectrum of endemic fluorosis: relationship with calcium intake. Skeletal Radiology 22: 257-61.

"High F intakes have been associated wtih a wide spectrum of bone diseases including osteosclerosis, osteoporosis, osteomalacia and exostoses... The pathogenic mechanisms underlying fluorosis of the mineralizing tissues have been studied extensively, but are still a matter of controversy."
SOURCE: Kragstrup J, et al. (1989). Effects of fluoride on cortical bone remodeling in the growing domestic pig. Bone 10:421-424.

"We suggest that bone fluorosis be classified roentgenologically on the basis of these 3 features into 3 types: the osteosclerosis type (53 cases, 36.3%), osteoporosis type (18 cases, 12.3%), and mixed type (51 cases, 34.9%)... In mixed type fluorosis, osteosclerosis, osteoporosis and osteomalacia exist in one patient."
SOURCE: Xu JC, et al. (1987). X-ray findings and pathological basis of bone fluorosis. Chinese Medical Journal 100:8-16.

"A combination of osteosclerosis, osteomalacia and osteoporosis of varying degrees as well as exostoses formation characterzes the bone lesions. In a proportion of cases secondary hyperparathyroidism is observed with associated characteristic bone changes." |
SOURCE: Krishnamachari KA. (1986). Skeletal fluorosis in humans: a review of recent progress in the understanding of the disease. Progress in Food and Nutrition Sciences 10(3-4):279-314.

"It is very interesting to observe that in the majority of our cases, osteosclerosis in the spine and pelvis was always combined with osteoporosis of the long bones. It might be an indication that the axial skeleton undergoes a quite different pathological process from the appendicular skeleton..."
SOURCE: Lian ZC, Wu EH. (1986). Osteoporosis--an early radiographic sign of endemic fluorosis. Skeletal Radiology 15:350-3.

"Radiographic appearances varied between individuals. Conflicting changes such as both decreased and increased density, coarsened, thinned and blurred trabeculae, coexisted not only in different bones of one individual, but also in one and the same bone. Some cases showed axial osteosclerosis exclusively, others axial osteosclerosis in association with peripheral osteoporosis or osteomalacia... Combinations of various changes produced a wide sprectrum of radiological changes."
SOURCE: Daijei H. (1984). Further observations on radiological changes of endemic foodborne skeletal fluorosis. Fluoride 17: 9-14.

"[N]ew bone formed under the stimulus of fluoride administration may exhibit various degrees of osteosclerosis, osteoporosis, osteomalacia, and architectural disorganization. Of these manifestations, only osteosclerosis increases bone strength. When fluoride is used therapeutically, therefore, it is obvious that conditions must be carefully chosen so as to maximize the development of osteosclerosis and to minimize the undesirable manifestations of osteoporosis and osteomalacia."
SOURCE: Riggs BL. (1983). Treatment of osteoporosis with sodium fluoride: An appraisal. Bone and Mineral Research. 2: 366-393.

"The changes described did not always develop in a progressive, predictable pattern to the adult stage of osteofluorosis."
SOURCE: Christie DP. (1980). The spectrum of radiographic bone changes in children with fluorosis. Radiology 136:85-90.

"The considerable individual variability of skeletal response to excessive fluoride ingestion implies that causative factors other than total daily ingestion of fluoride exist."
SOURCE: Christie DP. (1980). The spectrum of radiographic bone changes in children with fluorosis. Radiology 136:85-90.

"The osseous changes in fluorosis have been described as osteosclerosis, exostosis, hyperostosis, osteoporosis, osteomalacia, and rickets. Many questions arise as to why sometimes one type of osteopathy is induced and another at other times. The pathogenesis of the osseous changes in fluorosis has not been uncovered. Hodge and Smith (1965) commented on the cellular mechanisms whereby the bone lesions are induced in fluorosis: 'Questions are many, and answers are few, indeed, practically non-existent.'"
SOURCE: Krook L, Maylin GA. (1979). Industrial fluoride pollution. Chronic fluoride poisoning in Cornwall Island cattle. Cornell Veterinarian 69(Suppl 8): 1-70.

"The findings of osteosclerosis, osteomalacia and increased bone resorption have been confirmed in experimental fluorosis in animals. It can be seen, therefore, that fluoride bone disease could mimic renal osteodystrophy."
SOURCE: Cordy PE, et al. (1974). Bone disease in hemodialysis patients with particular reference to the effect of fluoride. Transactions of the American Society of Artifical Internal Organs 20: 197-202.

"In the final analysis it would be surprising if the complicated effects of fluoride on bone did not reflect the versatility of fluorine, the most reactive and the most stronly electronegative of all elements."
SOURCE: Faccini JM, Teotia SPS. (1974). Histopathological assessment of endemic skeletal fluorosis. Calcified Tissue Research 16: 45-57.

"To this day, many investigators still think of fluorosis exclusively in terms of osteosclerosis, whether crippling or non-crippling. This attitude is no longer valid, because osteosclerosis is only one of many skeletal abnormalities that can be induced by fluoride."
SOURCE: Marier JR, Rose D. (1971). Environmental fluoride. National Research Council of Canada, Publication No. 12,226, Ottawa.

"The osteofluorotic lesions may be porosis, sclerosis, hyperostosis, osteophytosis, and malacia, depending on the interacting factors influencing the degree of fluorosis."
SOURCE: Shupe JL, Olson AE. (1971). Cinical aspects of fluorosis in horses. Journal of the American Veterinary Association. 158: 167-174.

"Skeletal fluorosis has been likened to a number of bone diseases. The dense radiographic picture of the skeleton has resulted in comparison with osteosclerosis; the presence of broad osteoid seams has suggested osteomalacia; the way in which bone formation may proceed side by side with bone destruction is reminiscent of Paget's disease and the often excessive resorption points to osteoporosis."
SOURCE: Jolly SS. (1970). Hydric fluorosis in Punjab. In: TL Vischer. (1970). Fluoride in Medicine. Hans Huber, Bern. pp. 106-121.

"the findings in spontaneous and experimental fluorosis are, in part, contradictory. Human patients are usually diagnosed as having osteosclerosis whereas animals are described as having osteoporosis or 'osteomalacia'. Our radiograms might indicate that both processes are taking place, the sclerosis predominating over the greater part of most of the bones but osteoporosis being evident near the ends of some long bones."
SOURCE: Kilborn LG, et al. (1950). Fluorosis with report of an advanced case. Canadian Medical Association Journal 62: 135-141.

"Chronic fluorosis presented by some 10,000 inhabitants of the Argentine Republic is an anomaly of calcium metabolism involving not only the teeth but in addition the entire osseous system and characterized by generalized osteoporosis."
SOURCE: Silva LL, et al. (1940). Fluorosis and tuberculosis. La Semana Medica 24: 1413-1434.

"The osseous tissue displays a curious double reaction: sometimes an increased precipitation of mineral salts accompanied by stimulated growth, sometimes a reduced mineralization with mostly atrophying processes."
SOURCE: Roholm K. (1937). Fluoride intoxication: a clinical-hygienic study with a review of the literature and some experimental investigations. London: H.K. Lewis Ltd.

"It is extremely probable that fluorine acts on the metabolism in various ways and that the symptoms of chronic intoxication have a complicated genesis."
SOURCE: Roholm K. (1937). Fluoride intoxication: a clinical-hygienic study with a review of the literature and some experimental investigations. London: H.K. Lewis Ltd

Excerpts from the Scientific Literature - Reason for Variability Unclear: (back to top)

"Although this disorder has a wide variety of appearances, little attention has been given to the spectrum of radiologic appearances... The pathogenesis of these diverse radiologic appearances remains unclear."
SOURCE: Wang Y, et al. (1994). Endemic fluorosis of the skeleton: radiographic features in 127 patients. American Journal of Roentgenology 162: 93-8.

"The pathogenic mechanisms underlying fluorosis of the mineralizing tissues have been studied extensively, but are still a matter of controversy."
SOURCE: Kragstrup J, et al. (1989). Effects of fluoride on cortical bone remodeling in the growing domestic pig. Bone 10:421-424.

"Many questions arise as to why sometimes one type of osteopathy is induced and another at other times. The pathogenesis of the osseous changes in fluorosis has not been uncovered. Hodge and Smith (1965) commented on the cellular mechanisms whereby the bone lesions are induced in fluorosis: 'Questions are many, and answers are few, indeed, practically non-existent.'"
SOURCE: Krook L, Maylin GA. (1979). Industrial fluoride pollution. Chronic fluoride poisoning in Cornwall Island cattle. Cornell Veterinarian 69(Suppl 8): 1-70.

"It appears that there are some factors yet unknown which a play a part in determining the pattern of skeletal changes."
SOURCE: Makhni SS, et al. (1977). Long-term effects of fluoride administration: an experimental study. Fluoride 10:82-86.

"The histopathogenesis of the bone disease produced by chronic fluoride intoxication remains incompletely understood despite innumerable reports in the literature of the results of animal experimentation... In the final analysis it would be surprising if the complicated effects of fluoride on bone did not reflect the versatility of fluorine, the most reactive and the most stronly electronegative of all elements...Most probably all these factors are involved."
SOURCE: Faccini JM, Teotia SPS. (1974). Histopathological assessment of endemic skeletal fluorosis. Calcified Tissue Research 16: 45-57.

"Despite the large volume of research, however, the effects of fluoride on bone are complicated and are still not fully understood."
SOURCE: Faccini JM. (1969). Fluoride and bone. Calcified Tissue Research 3:1-16.

Excerpts from the Scientific Literature - Common Explanations Offered for Variability: (back to top)

a) Multifactorial: (back to top)

"It is generally thought that several factors influence the type of bone change seen in fluoride intoxication. These include the nature, dose, and duration of fluoride exposure; nutritional status; hormonal responses; age; sex; type of bone affected (cortical or otherwise); and dietary habits... The different appearances of this disease probably represent different combinations of these variables."
SOURCE: Wang Y, et al. (1994). Endemic fluorosis of the skeleton: radiographic features in 127 patients. American Journal of Roentgenology 162: 93-8.

b) Dose of Fluoride: (back to top)

"We found that fluoride increased cancellous bone area in the rat at the lower dose and reduced cancellous bone volume at the higher dose... Our findings suggest that the optimal concentration of fluoride that increases bone resorption is higher than the concentration that increases formation. If this is correct, the effects of fluoride on bone formation and resorption may be mediated through different mechanisms and may be dissociable."
SOURCE: Turner RT, et al. (1989). The effects of fluoride on bone and implant histomorphometry in growing rats. Journal of Bone and Mineral Research 4: 477-484.

"Osteosclerotic picture is evident when small doses of fluoride are ingested over a long period of time during which calcium intakes are apparently normal while osteoporotic forms are common in pediatric age group and with higher body load of the element."
SOURCE: Krishnamachari KA. (1986). Skeletal fluorosis in humans: a review of recent progress in the understanding of the disease. Progress in Food and Nutrition Sciences 10:279-314.

"Roholm (1937) realised, however, that an increase in bone growth and calcification resulted from comparatively small doses of fluorides, while large doses produced an atrophic state with a reduction in calcification."
SOURCE: Faccini JM. (1969). Fluoride and bone. Calcified Tissue Research 3:1-16.

"The osteoporotic stage of the disease occurs only when fluoric intoxication is very severe."
SOURCE: Soriano, M. (1968). Periostitis deformans due to wine fluorosis. Fluoride 1: 56-64.

"In the adult the osteosclerotic process seems to be produced by comparatively small quantities of fluorine, the osteoporotic process seems to be produced by comparatively large quantities."
SOURCE: Roholm K. (1937). Fluoride intoxication: a clinical-hygienic study with a review of the literature and some experimental investigations. London: H.K. Lewis Ltd.

c) Nutritional Status: (back to top)

"The toxic effects of fluoride were more severe and more complex and the incidence of metabolic bone disease (rickets, osteoporosis, Parathyroid Hormone bone disease) and bony leg deformities (genu valgum, genu varum, bowing, rotational and wind-swept) was greater (>90%) in children with calcium deficiency as compared to in children with adequate calcium who largely had osteoslcerotic form of skeletal fluorosis..."
SOURCE: Teotia M, Teotia SP, Singh KP. (1998). Endemic chronic fluoride toxicity and dietary calcium deficiency interaction syndromes of metabolic bone disease and deformities in India: year 2000. Indian Journal of Pediatrics 65:371-81.

"On the basis of our results, we suggest that fluoride toxicity in subjects with a reasonable calcium intake leads to typical osteosclerosis, while a calcium - (and protein-) deficient diet together with fluoride excess may be responsible for the osteopenic forms of the disease."
SOURCE: Mithal A, et al. (1993). Radiological spectrum of endemic fluorosis: relationship with calcium intake. Skeletal Radiology 22: 257-61.

"Osteosclerotic picture is evident when small doses of fluoride are ingested over a long period of time during which calcium intakes are apparently normal while osteoporotic forms are common in pediatric age group and with higher body load of the element."
SOURCE: Krishnamachari KA. (1986). Skeletal fluorosis in humans: a review of recent progress in the understanding of the disease. Progress in Food and Nutrition Sciences 10:279-314.

d) Area of Skeleton Impacted: (back to top)

"In skeletal fluorosis, the spinal column is the site of election. Spinal osteosclerosis resulting from chronic fluoride intoxication may be expected to divert calcium preferentially to the spinal column at the expense of limb bones. In the presence of low dietary calcium such diversion may well result in osteoporosis of the limb bones."
SOURCE: Krishnamachari KA, Krishnaswamy K. (1973). Genu valgum and osteoporosis in an area of endemic fluorosis. The Lancet 2: 877-879.

* For more information, on fluoride's differential impact on the skeleton, click here