Maxillary Molar Extraction Decreases Stiffness of the Mandible in Ovariectomized Rats

Abstract

Although osteoporosis is a major public health concern, the effect of this condition on oral bone has not been determined. Using the ovariectomized rat as a model, we examined whether acute estrogen depletion affects the mandible of the ovariectomized rat with and without maxillary molar extraction. Twenty-two ovariectomized and 20 sham-ovariectomized 90-day-old Sprague-Dawley rats were divided into the following groups: (1) sham-ovariectomized, baseline control; (2) ovariectomized, baseline control; (3) ovariectomized; (4) ovariectomized, tooth extraction; (5) sham-ovariectomized; and (6) sham-ovariectomized, tooth extraction. On day eight, sham-ovariectomized and ovariectomized rats had all their maxillary molars extracted, and the baseline control sham-ovariectomized and ovariectomized rats were killed. On day 35, the remaining animals were killed. After teeth were harvested, the right mandible was tested to failure in three-point bending. The bone mineral density of the left mandible was measured with dual-energy x-ray absorptiometry. The area fraction and area moment of inertia of a section of mandible were determined. Neither ovariectomy nor tooth extraction significantly affected the bone mineral density or structural properties of the rat mandible. However, there was an interaction between ovariectomy and maxillary molar extraction on the stiffness of the rat mandible (p < 0.008). Maxillary molar extraction decreased the stiffness of the mandible by 25% (p < 0.05) in the ovariectomized rat, whereas it did not do so in the sham-ovariectomized rat.

Keywords

Osteoporosis Ovariectomy Oral Bone Loss Biomechanics.

Get full access to this article

View all access options for this article.

References

Beer FP , Johnston ER (1981). In: Mechanics of materials. New York: McGraw-Hill.

Bustillo F. , Kosinski T. , Bachtell R. (1986). A preliminary study of 37 subperiosteal implant candidates with atrophic mandibles. J Oral Implantol 12:218-227.

Consensus Development Conference (1991). Prophylaxis and treatment of osteoporosis. Conference Report. Am J Med 90:107-110.

Fisher A. , Williams D. , Bradley P. (1977). The effect of cryosurgery on the strength of bone . Br J Oral Surg 15:215-222.

Frost H. , Jee W. (1992). On the rat model of human osteopenias and osteoporoses . Bone Miner 18:227-236.

Guy JA , Shea M. , Peter CP , Morrissey R. , Hayes WC (1993). Continuous alendronate treatment through growth, maturation and aging in the rat results in increases in bone mass and mechanical properties. Calcif Tissue Int 53:283-288.

Kalu D. , Chung-Ching L. , Hardin R. , Hollis B. (1989). The aged rat model of ovarian hormone deficiency bone loss. Endocrinol 124:7-16.

Kimmel D. , Wronski TJ (1990). Nondestructive measurement of bone mineral in femurs from ovariectomized rats. Calcif Tissue Int 46:101-110.

King GJ , Wronski TJ (1993). Histomorphometric assessment of alveolar bone turnover in the estrogen deprived rat (abstract). J Bone Min Res 8(Suppl 1):653.

10.

Kribbs PJ , Smith DE , Chestnut CH III (1983). Oral findings in osteoporosis. Part II: Relationship between residual ridge and alveolar bone resorption and generalized skeletal osteopenia. J Prosthet Dent 50:719-724.

11.

Levy G. , Mailland M. (1980). Histologic study of the effects of occlusal hypofunction following antagonist tooth extraction in the rat. J Periodontol 15:393-399.

12.

Manson JD (1976). Bone morphology and bone loss in periodontal disease . J Clin Periodontol 3:14-22.

13.

McCord J. , Bradley P. (1989). Observations on the effects of two ceramics on the strength of bone subjected to cryosurgery. Br J Oral Max Surg 27:217-223.

14.

Miller SC , Bowman BM , Miller MA , Bagi CM ( 1991). Calcium absorption and osseous organ-, tissue-, and envelope-specific changes following ovariectomy in rats. Bone 2:439-446.

15.

Mohajery M. , Brooks S. (1992). Oral radiographs in the detection of early signs of osteoporosis. Oral Surg Oral Med Oral Pathol 73:112-117.

16.

Mosekilde L. , Danielsen CC , Knudsen UB (1993). The effect of aging and ovariectomy on the vertebral bone mass and biomechanical properties of mature rats. Bone 14:1-6.

17.

Nishimura I. , Damiani PJ , Atwood DA (1987). Resorption of residual ridges (RRR) in rats. J Dent Res 66:1753-1757.

18.

Nishimura I. , Hosokawa R. , Atwood DA (1992). The knife-edge tendency in mandibular residual ridges in women. J Prosthet Dent 67:820-826.

19.

Ortman LF , Haussmann E. , Dunford RG (1989). Skeletal osteopenia and residual ridge resorption . J Prosthet Dent 61:321-325.

20.

Pelker R. , Friedlaender G. , Markham T. , Panjabi M. , Moen C. ( 1984). Effects of freezing and freeze-drying on the biomechanical properties of rat bone. J Orthop Res 1:405-411.

21.

Toolan BC , Shea M. , Myers ER , Borchers RE , Seedor JG , Quartuccio H. , et al. (1992). Effect of 4-amino-1-hydroxybutylidene bisphosphonate on bone biomechanics in rats. J Bone Miner Res 7:1399-1406.

22.

Wowern N. , Hjorting-Hansen E. , Stoltze K. (1979). Changes in bone mass in rat mandibles after tooth extraction. Int J Oral Surg 8:229-233.

23.

Wronski TJ (1992). The ovariectomized rat as an animal model for postmenopausal bone loss. Cells and Mater 1 (Supp 1):69-74.