- Email: [email protected]
A review of residual ridge resorption and bone density
A review Esa Klemetti,
of residual DDS,
ridge resorption
and bone density
PbDa
University of Kuopio, Kuopio, Finland Residual ridge resorption is a common and often incapacitating problem, particularly for persons with edentulous mandibles. Several studies suggest a correlation between ridge resorption and osteoporosis. Recent radiologic studies indicate that the mineral density of the cortex and the bone mass in the mandible are correlated with skeletal bone density. Most resorption occurs in the alveolar process, whereas the basal portion remains relatively intact. On the other hand, radiologic measurements of bone density primarily yield information about the basal portion, where the bone mass of the mandible is greatest and functional stresses of mastication may affect bone density. Ironically, radiologic meas~ments may not accurately indicate the effect of osteoporosis on alveolar resorption. Apparently, excessive occlusal force can also produce extensive atrophy without systemic impact. Not until muscular function decreases does real osteoporosis deveiop in edentulous jaws. Not only does the volume of the ridge decrease, but also the density of the basal portion decreases as a result of diminished function. This article reviews the literature on residual ridge resorption and components that may affect the rate of resorption. (J PROSTHET DENT 1996;7&X&4.f
E
very year generalized loss of minerals from the skeleton, osteoporosis, causes thousands of spinal and hip fractures, which in the elderly may lead to invalidism and death. Those fractures, which are the most si~i~cant effect of generalized bone loss, atso have important socioeconomic consequences. After extraction of teeth, the alveolar portion of the jaws starts to atrophy; this is also referred to as residual ridge resorption (RRR). This o&en leads to a situation where there is no longer s~cie~t support for the proper functioning of removable complete dentures. The problem is worse in the mandible. So long as it does not interfere with the placement of implants, the quality of the bone in the jaws has little importance if neither fractures nor RRR takes place. In the skeleton, poor bone quality has no clinical significance until fracture occurs. Several studies suggest a correlation between alveolar atrophy and osteoporosis.‘-I1 However, not all RRR can be explained by the presence of generalized bone loss. Initiation of RRR is always preceded by loss of teeth and of their pe~odontal membranes, which has the ability to form bone.lz Severe RRR may also occur in individuals with good mineral status in the skeleton, and the height of the ridge does not seem to be related to the bone mineral density (BMD) of the ridge.1° The factors that affect the tissues of the alveolar ridges are quite different from those that affect other hard and soft tissues in the human body. Much work has been done to understand the biochemical aspects of bone resorption
aDepartmental Dentist, Department of Prostheticsand Stimatognathic
512
Physiology.
THE JOUR&iL
OF PROSTRETIC
DENTISTRY
caused by periodontal disease and its ass~iation with RRR after extraction of teeth. Endotoxins from dental plaque,13, l4 osteoclast-activating factor (OAF),15llci prostaglandins,17 and human gingival bone reso~tion-stimulating factor-r8 are all components that may have a significant effect on the rate of RRR. This effect could be called the local biochemical inheritance from the dentate period. This review of the literature focuses on residual ridge resorption and examines the differences in current research.
REVIEW
OF THE LITEMTtJR,E
After the age of 40 years, the BMD of the skeleton decreases, so that by the age of 65 years approximately one third of the bone minerals have been lost.lQ Decreased physical activity, lowered secretion of estrogen, diet, race, and heredity may all play a role in age-related bone ~oss.~O Age-related loss is also seen in the mandible.21 Clinically significant osteoporosis is more common in short, lightweight, nulliparous women than in tall, heavy women who have given birth. During the last 20 years new developments in imaging have facilitated determining BMD not only in the skeleton but also in the jaws. These studies show that in some phases of alveolar resorption generalized mineral loss from the skeleton affects the speed of RRR and the bone density of the jaws. Kribbs et aLz2 indicated that in postmenopausal women with osteoporosis the height of the edentulous alveolar ridge is correlated with the total amount of calcium in the body. This finding suggests that individuals with severe osteoporosis retain less alveolar bone once the teeth are extracted. Von Wowern and Melsen23 reported that in healthy indi~duals the density of the bone in the
VOLUME
75
NUMRER
5
THE JOURNAL
IUEMElTI
iliac crest is not correlated with the bone mass of the mandible but with the BMD of the metacarpal bones. Von Wowerns found that in both young dentate people and old edentate people the mineral content of the bones of the forearm correlated with that of the mandible. On the other between hand, Von Wowern et al. 24 found no relationship the mineral content in the mandible and that of the lumbar spine. IGibbs suggested that the bone mass of the mandible depends more on the status of the bony tissues in the whole skeleton than on age. Low bone density in the skeleton is accepted as a predisposing factor for rapid RRR in the mandible but, because skeletal BMD is correlated with mandibular BMD, high local BMD values have been seen as an indication that bony tissues are protected against RRR. The cortical and trabecular portions of the mandible seem to behave differently with age. The cortical bone mass diminishes considerably over the years, but the trabecular portion shows marked individual variation in all age groups.z5 Von Wowern and Kollerup6 suggested that symptomatic osteoporosis might be a severe risk factor for RRR in the maxilla but not in the mandible. The differing amounts of trabecular and cortical bone in the maxilla and mandible may actually play a role in determining how sensitive the structures are to the various systemic or local resorptive factors. Klemetti and Vainio” reported that the remaining height of the edentulous mandibles was more dependent on the BMD values of the femoral neck than on the BMD of the lumbar spine. The height of the maxillary ridge, on the other hand, seemed to be more closely related to the lumbar values. This may be because the amount of cortical bone in the femoral neck, approximately 75% is similar to that in the mandible and the bone in both the lumbar spine and the maxilla is primarily trabecular. Several previous reports confirm that the alveolar process and the basal portion behave differently over the years. According to Von Wowern5 and Von Wowern and Stoltze,21 the age-related increase in cortical porosity and thinning occur primarily in the alveolar process, whereas the basal portion remains more intact. Atkinson and Woodheadl stated that the buccal cortex of the alveolar process of the mandible becomes more porotic with age than the basal portion does. These results were confirmed by Klemetti et al. ‘9 lo, 26-30 According to their results, functional stress caused by the masticatory muscles is involved in maintaining BMD in edentulous areas of the mandible. After extraction of teeth, those individuals who are physically active or are bruxers may lose smaller amounts of minerals from those regions of the mandible where the muscles are attached.26*27 In addition, the BMD of the cortical bone in the edentulous mandible is not lowered by mechanical stress caused by the remaining natural teeth in the maxilla, but the BMD of the trabecular portion is lowered.28 If the teeth in the maxilla were extracted early in life during the rapid phase of bone metabolism, the
MAY 1996
OF PROSTRETIC
DENTISTRY
Fig. 1. Attachments of masticatory muscles in molar region of mandible affect bone density of basal portion. Alveolar process is exposed to bite pressure. Mu, Masseter muscle; B, buccinator; My, mylohyoid muscle; N, mandibular nerve.
ridges would be less disposed to the occlusal trauma caused by the presence of the mandibular incisors than for individuals who lost their teeth in middle or old age.2g This finding also indicates that local biochemical inheritance from the dentate period may affect the rate of RRR.
DISCUSSION Most of the bone mass in the mandible consists of cortical bone in the basal portion, The trabecular bone exhibits marked individual variation in BMD,25, 3o whereas the BMD values for cortical bone are more likely to be correlated with those of the skeleton.gx 27 On the other hand, the BMD and thickness of the cortical bone mass in the mandible is affected by the forces of the masticatory muscles25-27 in the basal portion where the muscles are attached (Fig. 1). Physical activity and good physical or muscular condition are correlated with high skeletal BMD. According to accepted clinical findings, most RRR occurs in the alveolar process, the part of the mandible where the roots of the teeth were situated, and the basal portion remains more intact. On the other hand, even modern radiologic measurements of BMD in edentulous mandibles usually provide information about the BMD of the basal portion. Because of this paradox, radiologic BMD measurements may not depict the ability of osteoporosis to cause RRR, but rather the impact of muscle function on bone density. With age and progressive atrophy of the ridge, muscular function decreases to protect the bony structures of the
513
THE JOURNAL
OF PROSTHETIC
DENTISTRY
ridges, especially in the mandible.31s 32 Functional stress and irritation also decrease in those regions where the muscles are attached. Not until this phase does real osteoporosis develop in the mandible. The volume of the ridge and the BMD of the basal portion decrease as a result of reduced function. Bone tissues may develop rapid RRR in individuals with osteoporosis, low density, and low metabolism of the bone, even when biting forces are low or normal. However, owing to muscle tonus, the measured bone density may be moderately high. For individuals with high skeletal and mandibular BMD, muscular activity may cause enough pressure against the alveolar ridges to provoke RRR. The rate of RRR may also be affected by biochemical inheritance from the dentate period, the effect of which is focused on those structures where the roots of the teeth were situated.2g The primary health effects of generalized bone loss in the skeleton are fractures of the long bones and spine. Because of its similar etiology, residual ridge resorption might be compared with skeletal fractures; osteoporosis predisposes bone to the injurious impact of mechanical forces.
SUMMARY Based on the review of the literature, occlusal forces must be considered to be the major cause of RRR because these forces are able to cause rapid and thorough resorption without systemic bone loss, namely, osteoporosis. Measurements of the bone mineral density of the mandible do not accurately predict the tendency toward residual ridge resorption. REFERENCES 1. Atkinson PJ, Woodhead C. Changes in human mandibular structure with age. Arch Oral Biol 1968;13:1453-64. 2. Atwood DA, Coy WA. Clinical, cephalometric, and densitometric study of reduction of residual ridges. J PROWHET DENT 1971;26:280-95. 3. Baylink DJ, Wergedal JE, Yamamoto K, Manzke E. Systemic factors in alveolar bone loss. J PROSTHET DENT 1974;31:486-505. 4. Sones AD, Wolinsky LE, Kratochvil FJ. Osteoporosis and mandibular bone resorption: a prosthodontic perspective. J PROSTHET DENT 1986; 56:732-6. 5. Von Wowern N. In vivo measurement of bone mineral content of mandibles by dual-photon absorptiometry. Stand J Dent Res 1985;93:162-8. 6. Von Wowern N, Kollerup G. Symptomatic osteoporosis: a risk factor for residual ridge reduction of the jaws. J PROSTHET DENT 1992;67:656-60. 7. Kribbs PJ. Comparison of mandibular bone in normal and osteoporotie women. J PROSTHET DENT 1990;63:218-22. 8. Kribbs PJ. Two-year changes in mandibular bone mass in an osteoporotic population. J PROSTHET DENT 1992;67:653-5. 9. Klemetti E, Vainio P, Lassila V, Alhava E. Cortical bone mineral density in the mandible and osteoporosis status in post-menopausal women. Stand J Dent Res 1993;101:219-23. 10. Klemetti E, Vainio P. Effect of bone mineral density in skeleton and mandible on extraction of teeth and clinical alveolar height. J PROSTHET DENT 1993;70:21-5.
514
RLEMETTI
11. Klemetti E, Kolmakow S, Kx%ger H. Pantomography in assessment of osteoporosis risk. Stand J Dent Res 1994;102:68-72. 12. Miles AE. ‘Sans teeth’: changes in oral tissues with advancing age. Proc R Sot Med 1972;65:801-6. 13. Hausmann E. Potential pathways for bone resorption in human periodontal disease. J Periodontol 1974;45:338-43. 14. Hausmann E, Raisz LG, Miller WA. Endotoxin: stimulation of bone resorption in tissue culture. Science 1970;168:862-4. KE. Regulation of osteoclast acti15 Horton JE, Wezeman FH, Kuettner vating factor-stimulated bone resorption in vitro with an inhibitor of collagenase. In: Horton JE, Tarpley, Davis, eds. Proceedings, mechanisms of localized bone loss. Special Supplement to Calcified Tissue Abstracts 1978:127-49. 16. Chambers TJ. The pathobiology of the osteoclast. J Clin Path01 1985;38:241-52. 17 Offenbacher S, Odle BM, van Dyke TE. The use of crevicular fluid prostaglandin E2 levels as a predictor of periodontal attachment loss. J Periodontal Res 1986;21:101-12. 18. Goldhaber P, Rabadjija L, Beyer WR, Kornhauser A. Bone resorption in tissue culture and its relevance to periodontal disease. J Am Dent Assoc 1973;87:1027-33. 19. Gordan GS, Genant HK The aging skeleton. Clin Geriatr Med 1985;l: 95-118. 20. Krolner B, Taft B. Vertebral bone loss: an unheeded side effect of therapeutic bed rest. Clin Sci 1983;64:537-40. 21. Von Wowern N, Stoltze K. Age differences in cortical width of mandibles determined by histoquantitation. Stand J Dent Res 1979;87:22533. 22. Kribbs PJ, Chesnut CH III, Ott SM, Kilcoyne RF. Relationships between mandibular and skeletal bone in an osteoporotic population. J PROSTHET DENT 1989;62:703-7. 23. Von Wowern N, Melsen F. Comparative bone morphometric analysis of mandibles and iliac crests. &and J Dent Res 1979;87:351-7. 24. Von Wowern N, Storm TL, Olgaard K. Bone mineral content by photon absorptiometry of the mandible compared with that of the forearm and the lumbar spine. Calcif Tissue Int 1988;42:157-61. 25. Van Wowern N, Stoltze K. Sex and age differences in bone morphology of mandibles. Stand J Dent Res 1978;86:478-85. 26. Klemetti E, Vainio P, Lassila V. Mineral density in the mandibles of partially and totally edentate women. Stand J Dent Res 1994;102:64-7. 27. Klemetti E, Vainio P, Krijger H. Muscle strength and mineral densities in the mandible. Gerodontology 1994;11:76-9. 28. Klemetti E, Vainio P. Effect of maxillary edentulousness on mandibular residual ridges. Stand J Dent Res 1994;102:309-12. 29. Klemetti E. Resistance of the maxillary ridge to occlusal trauma. J PROSTHET DENT 1995;73:250-2. 30. Klemetti E, Vainio P, Lassila V, Alhava E. Trabecular bone mineral density and alveolar height in postmenopausal women. Stand J Dent Res 1993;101:166-70. 31. Tallgren A. The continuing reduction of the residual alveolar ridges in complete denture wearers: a mixed-longitudinal study covering 25 years. J PROSTHET DENT 1972;27:120-32. 32. Tallgren A, Lang BR, Walker GF, et al. Roentgen cephalometric analysis of ridge resorption and changes in jaw and occlusal relationships in immediate complete denture wearers. J Oral Rehabil 1980;7:77-94.
Reprintrequeststo: DR. E. KLEMETTI DEPARTMENT OF PROSTHETICS AND STOMATOGNATHIC UNIVERSITY OF KUOPIO P.O.B. 1627 SF-70211, KUOPIO FINLAND
Copyright
0 1996 by The Editorial
PROSTHETIC DENTISTRY. 0022-3913/96/$5.00 + 0.
PHYSIOLOGY
Council of THE
JOURNAL
OF
10/l/71248
VOLUME
75
NIJMRER
6
of residual DDS,
ridge resorption
and bone density
PbDa
University of Kuopio, Kuopio, Finland Residual ridge resorption is a common and often incapacitating problem, particularly for persons with edentulous mandibles. Several studies suggest a correlation between ridge resorption and osteoporosis. Recent radiologic studies indicate that the mineral density of the cortex and the bone mass in the mandible are correlated with skeletal bone density. Most resorption occurs in the alveolar process, whereas the basal portion remains relatively intact. On the other hand, radiologic measurements of bone density primarily yield information about the basal portion, where the bone mass of the mandible is greatest and functional stresses of mastication may affect bone density. Ironically, radiologic meas~ments may not accurately indicate the effect of osteoporosis on alveolar resorption. Apparently, excessive occlusal force can also produce extensive atrophy without systemic impact. Not until muscular function decreases does real osteoporosis deveiop in edentulous jaws. Not only does the volume of the ridge decrease, but also the density of the basal portion decreases as a result of diminished function. This article reviews the literature on residual ridge resorption and components that may affect the rate of resorption. (J PROSTHET DENT 1996;7&X&4.f
E
very year generalized loss of minerals from the skeleton, osteoporosis, causes thousands of spinal and hip fractures, which in the elderly may lead to invalidism and death. Those fractures, which are the most si~i~cant effect of generalized bone loss, atso have important socioeconomic consequences. After extraction of teeth, the alveolar portion of the jaws starts to atrophy; this is also referred to as residual ridge resorption (RRR). This o&en leads to a situation where there is no longer s~cie~t support for the proper functioning of removable complete dentures. The problem is worse in the mandible. So long as it does not interfere with the placement of implants, the quality of the bone in the jaws has little importance if neither fractures nor RRR takes place. In the skeleton, poor bone quality has no clinical significance until fracture occurs. Several studies suggest a correlation between alveolar atrophy and osteoporosis.‘-I1 However, not all RRR can be explained by the presence of generalized bone loss. Initiation of RRR is always preceded by loss of teeth and of their pe~odontal membranes, which has the ability to form bone.lz Severe RRR may also occur in individuals with good mineral status in the skeleton, and the height of the ridge does not seem to be related to the bone mineral density (BMD) of the ridge.1° The factors that affect the tissues of the alveolar ridges are quite different from those that affect other hard and soft tissues in the human body. Much work has been done to understand the biochemical aspects of bone resorption
aDepartmental Dentist, Department of Prostheticsand Stimatognathic
512
Physiology.
THE JOUR&iL
OF PROSTRETIC
DENTISTRY
caused by periodontal disease and its ass~iation with RRR after extraction of teeth. Endotoxins from dental plaque,13, l4 osteoclast-activating factor (OAF),15llci prostaglandins,17 and human gingival bone reso~tion-stimulating factor-r8 are all components that may have a significant effect on the rate of RRR. This effect could be called the local biochemical inheritance from the dentate period. This review of the literature focuses on residual ridge resorption and examines the differences in current research.
REVIEW
OF THE LITEMTtJR,E
After the age of 40 years, the BMD of the skeleton decreases, so that by the age of 65 years approximately one third of the bone minerals have been lost.lQ Decreased physical activity, lowered secretion of estrogen, diet, race, and heredity may all play a role in age-related bone ~oss.~O Age-related loss is also seen in the mandible.21 Clinically significant osteoporosis is more common in short, lightweight, nulliparous women than in tall, heavy women who have given birth. During the last 20 years new developments in imaging have facilitated determining BMD not only in the skeleton but also in the jaws. These studies show that in some phases of alveolar resorption generalized mineral loss from the skeleton affects the speed of RRR and the bone density of the jaws. Kribbs et aLz2 indicated that in postmenopausal women with osteoporosis the height of the edentulous alveolar ridge is correlated with the total amount of calcium in the body. This finding suggests that individuals with severe osteoporosis retain less alveolar bone once the teeth are extracted. Von Wowern and Melsen23 reported that in healthy indi~duals the density of the bone in the
VOLUME
75
NUMRER
5
THE JOURNAL
IUEMElTI
iliac crest is not correlated with the bone mass of the mandible but with the BMD of the metacarpal bones. Von Wowerns found that in both young dentate people and old edentate people the mineral content of the bones of the forearm correlated with that of the mandible. On the other between hand, Von Wowern et al. 24 found no relationship the mineral content in the mandible and that of the lumbar spine. IGibbs suggested that the bone mass of the mandible depends more on the status of the bony tissues in the whole skeleton than on age. Low bone density in the skeleton is accepted as a predisposing factor for rapid RRR in the mandible but, because skeletal BMD is correlated with mandibular BMD, high local BMD values have been seen as an indication that bony tissues are protected against RRR. The cortical and trabecular portions of the mandible seem to behave differently with age. The cortical bone mass diminishes considerably over the years, but the trabecular portion shows marked individual variation in all age groups.z5 Von Wowern and Kollerup6 suggested that symptomatic osteoporosis might be a severe risk factor for RRR in the maxilla but not in the mandible. The differing amounts of trabecular and cortical bone in the maxilla and mandible may actually play a role in determining how sensitive the structures are to the various systemic or local resorptive factors. Klemetti and Vainio” reported that the remaining height of the edentulous mandibles was more dependent on the BMD values of the femoral neck than on the BMD of the lumbar spine. The height of the maxillary ridge, on the other hand, seemed to be more closely related to the lumbar values. This may be because the amount of cortical bone in the femoral neck, approximately 75% is similar to that in the mandible and the bone in both the lumbar spine and the maxilla is primarily trabecular. Several previous reports confirm that the alveolar process and the basal portion behave differently over the years. According to Von Wowern5 and Von Wowern and Stoltze,21 the age-related increase in cortical porosity and thinning occur primarily in the alveolar process, whereas the basal portion remains more intact. Atkinson and Woodheadl stated that the buccal cortex of the alveolar process of the mandible becomes more porotic with age than the basal portion does. These results were confirmed by Klemetti et al. ‘9 lo, 26-30 According to their results, functional stress caused by the masticatory muscles is involved in maintaining BMD in edentulous areas of the mandible. After extraction of teeth, those individuals who are physically active or are bruxers may lose smaller amounts of minerals from those regions of the mandible where the muscles are attached.26*27 In addition, the BMD of the cortical bone in the edentulous mandible is not lowered by mechanical stress caused by the remaining natural teeth in the maxilla, but the BMD of the trabecular portion is lowered.28 If the teeth in the maxilla were extracted early in life during the rapid phase of bone metabolism, the
MAY 1996
OF PROSTRETIC
DENTISTRY
Fig. 1. Attachments of masticatory muscles in molar region of mandible affect bone density of basal portion. Alveolar process is exposed to bite pressure. Mu, Masseter muscle; B, buccinator; My, mylohyoid muscle; N, mandibular nerve.
ridges would be less disposed to the occlusal trauma caused by the presence of the mandibular incisors than for individuals who lost their teeth in middle or old age.2g This finding also indicates that local biochemical inheritance from the dentate period may affect the rate of RRR.
DISCUSSION Most of the bone mass in the mandible consists of cortical bone in the basal portion, The trabecular bone exhibits marked individual variation in BMD,25, 3o whereas the BMD values for cortical bone are more likely to be correlated with those of the skeleton.gx 27 On the other hand, the BMD and thickness of the cortical bone mass in the mandible is affected by the forces of the masticatory muscles25-27 in the basal portion where the muscles are attached (Fig. 1). Physical activity and good physical or muscular condition are correlated with high skeletal BMD. According to accepted clinical findings, most RRR occurs in the alveolar process, the part of the mandible where the roots of the teeth were situated, and the basal portion remains more intact. On the other hand, even modern radiologic measurements of BMD in edentulous mandibles usually provide information about the BMD of the basal portion. Because of this paradox, radiologic BMD measurements may not depict the ability of osteoporosis to cause RRR, but rather the impact of muscle function on bone density. With age and progressive atrophy of the ridge, muscular function decreases to protect the bony structures of the
513
THE JOURNAL
OF PROSTHETIC
DENTISTRY
ridges, especially in the mandible.31s 32 Functional stress and irritation also decrease in those regions where the muscles are attached. Not until this phase does real osteoporosis develop in the mandible. The volume of the ridge and the BMD of the basal portion decrease as a result of reduced function. Bone tissues may develop rapid RRR in individuals with osteoporosis, low density, and low metabolism of the bone, even when biting forces are low or normal. However, owing to muscle tonus, the measured bone density may be moderately high. For individuals with high skeletal and mandibular BMD, muscular activity may cause enough pressure against the alveolar ridges to provoke RRR. The rate of RRR may also be affected by biochemical inheritance from the dentate period, the effect of which is focused on those structures where the roots of the teeth were situated.2g The primary health effects of generalized bone loss in the skeleton are fractures of the long bones and spine. Because of its similar etiology, residual ridge resorption might be compared with skeletal fractures; osteoporosis predisposes bone to the injurious impact of mechanical forces.
SUMMARY Based on the review of the literature, occlusal forces must be considered to be the major cause of RRR because these forces are able to cause rapid and thorough resorption without systemic bone loss, namely, osteoporosis. Measurements of the bone mineral density of the mandible do not accurately predict the tendency toward residual ridge resorption. REFERENCES 1. Atkinson PJ, Woodhead C. Changes in human mandibular structure with age. Arch Oral Biol 1968;13:1453-64. 2. Atwood DA, Coy WA. Clinical, cephalometric, and densitometric study of reduction of residual ridges. J PROWHET DENT 1971;26:280-95. 3. Baylink DJ, Wergedal JE, Yamamoto K, Manzke E. Systemic factors in alveolar bone loss. J PROSTHET DENT 1974;31:486-505. 4. Sones AD, Wolinsky LE, Kratochvil FJ. Osteoporosis and mandibular bone resorption: a prosthodontic perspective. J PROSTHET DENT 1986; 56:732-6. 5. Von Wowern N. In vivo measurement of bone mineral content of mandibles by dual-photon absorptiometry. Stand J Dent Res 1985;93:162-8. 6. Von Wowern N, Kollerup G. Symptomatic osteoporosis: a risk factor for residual ridge reduction of the jaws. J PROSTHET DENT 1992;67:656-60. 7. Kribbs PJ. Comparison of mandibular bone in normal and osteoporotie women. J PROSTHET DENT 1990;63:218-22. 8. Kribbs PJ. Two-year changes in mandibular bone mass in an osteoporotic population. J PROSTHET DENT 1992;67:653-5. 9. Klemetti E, Vainio P, Lassila V, Alhava E. Cortical bone mineral density in the mandible and osteoporosis status in post-menopausal women. Stand J Dent Res 1993;101:219-23. 10. Klemetti E, Vainio P. Effect of bone mineral density in skeleton and mandible on extraction of teeth and clinical alveolar height. J PROSTHET DENT 1993;70:21-5.
514
RLEMETTI
11. Klemetti E, Kolmakow S, Kx%ger H. Pantomography in assessment of osteoporosis risk. Stand J Dent Res 1994;102:68-72. 12. Miles AE. ‘Sans teeth’: changes in oral tissues with advancing age. Proc R Sot Med 1972;65:801-6. 13. Hausmann E. Potential pathways for bone resorption in human periodontal disease. J Periodontol 1974;45:338-43. 14. Hausmann E, Raisz LG, Miller WA. Endotoxin: stimulation of bone resorption in tissue culture. Science 1970;168:862-4. KE. Regulation of osteoclast acti15 Horton JE, Wezeman FH, Kuettner vating factor-stimulated bone resorption in vitro with an inhibitor of collagenase. In: Horton JE, Tarpley, Davis, eds. Proceedings, mechanisms of localized bone loss. Special Supplement to Calcified Tissue Abstracts 1978:127-49. 16. Chambers TJ. The pathobiology of the osteoclast. J Clin Path01 1985;38:241-52. 17 Offenbacher S, Odle BM, van Dyke TE. The use of crevicular fluid prostaglandin E2 levels as a predictor of periodontal attachment loss. J Periodontal Res 1986;21:101-12. 18. Goldhaber P, Rabadjija L, Beyer WR, Kornhauser A. Bone resorption in tissue culture and its relevance to periodontal disease. J Am Dent Assoc 1973;87:1027-33. 19. Gordan GS, Genant HK The aging skeleton. Clin Geriatr Med 1985;l: 95-118. 20. Krolner B, Taft B. Vertebral bone loss: an unheeded side effect of therapeutic bed rest. Clin Sci 1983;64:537-40. 21. Von Wowern N, Stoltze K. Age differences in cortical width of mandibles determined by histoquantitation. Stand J Dent Res 1979;87:22533. 22. Kribbs PJ, Chesnut CH III, Ott SM, Kilcoyne RF. Relationships between mandibular and skeletal bone in an osteoporotic population. J PROSTHET DENT 1989;62:703-7. 23. Von Wowern N, Melsen F. Comparative bone morphometric analysis of mandibles and iliac crests. &and J Dent Res 1979;87:351-7. 24. Von Wowern N, Storm TL, Olgaard K. Bone mineral content by photon absorptiometry of the mandible compared with that of the forearm and the lumbar spine. Calcif Tissue Int 1988;42:157-61. 25. Van Wowern N, Stoltze K. Sex and age differences in bone morphology of mandibles. Stand J Dent Res 1978;86:478-85. 26. Klemetti E, Vainio P, Lassila V. Mineral density in the mandibles of partially and totally edentate women. Stand J Dent Res 1994;102:64-7. 27. Klemetti E, Vainio P, Krijger H. Muscle strength and mineral densities in the mandible. Gerodontology 1994;11:76-9. 28. Klemetti E, Vainio P. Effect of maxillary edentulousness on mandibular residual ridges. Stand J Dent Res 1994;102:309-12. 29. Klemetti E. Resistance of the maxillary ridge to occlusal trauma. J PROSTHET DENT 1995;73:250-2. 30. Klemetti E, Vainio P, Lassila V, Alhava E. Trabecular bone mineral density and alveolar height in postmenopausal women. Stand J Dent Res 1993;101:166-70. 31. Tallgren A. The continuing reduction of the residual alveolar ridges in complete denture wearers: a mixed-longitudinal study covering 25 years. J PROSTHET DENT 1972;27:120-32. 32. Tallgren A, Lang BR, Walker GF, et al. Roentgen cephalometric analysis of ridge resorption and changes in jaw and occlusal relationships in immediate complete denture wearers. J Oral Rehabil 1980;7:77-94.
Reprintrequeststo: DR. E. KLEMETTI DEPARTMENT OF PROSTHETICS AND STOMATOGNATHIC UNIVERSITY OF KUOPIO P.O.B. 1627 SF-70211, KUOPIO FINLAND
Copyright
0 1996 by The Editorial
PROSTHETIC DENTISTRY. 0022-3913/96/$5.00 + 0.
PHYSIOLOGY
Council of THE
JOURNAL
OF
10/l/71248
VOLUME
75
NIJMRER
6