endodontics Editor: SAMUEL SELTZER,
DDS
Department of Endodontology School of Dentistry Temple University 3223 North Broad Street Philadelphia, Pennsylvania 19140
Vascular changes in the dental pulp in the hypercholesterolemic miniature swine Bamiduro R. Oguntebi, DDS, MS,a Douglas S. Staflord, DMD,b James Cerda, IMD,~ and Frank Robbins, ~VILY,~Gainesville, Fla. UNIVERSITY
OF FLORIDA,
AND VA MEDICAL
CENTER
The aim of this study was to evaluate the effect of hypercholesterolemia and a cholesterol-lowering diet on the blood vessels of dental pulp. Eighteen miniature swine were assigned to three different groups on the basis of their diets: hog finisher; hog finisher with added fat and cholesterol, or hog finisher with added fat and cholesterol supplemented with grapefruit pectin. The cholesterol levels were monitored monthly for the duration of the experiment. Biopsy specimens of the aorta, coronary arteries, kidneys, and mandibular incisor teeth were prepared for histologic examination. The degree of narrowing of the central pulpal arterioles was measured with a Bioquant II digitizer attached to an Apple Ile computer and a Nikon Labophot light microscope. A few (9.8%) of the pulpal arterioles of the swine on a high-cholesterol diet had atheromatous plaques, but no complete vascular obstructions were observed. No degenerative changes were observed in any of the dental pulps examined. (ORAL SURG ORAL MED ORAL PATHOL 1992;74:351-6)
C
oronary heart diseaseremains the leading cause of death in the United States.’ Evidence accumulated from genetic trials, animal diet experiments, and epidemiologic studies have implicated elevated levels of circulating cholesterol as a causal factor.* Clinical trials have also shown that lowering these lipid levels by drugs and/or diet reduces the cardiovascular risk.3$4Several hypocholesteremic drugs are available in clinical practice,5 and somenatural hypocholester*Associate Professor, Department of Endodontics, College of Dentistry, University of Florida. bResident, Department of Dentistry, VA Medical Center. cProfessor, Department of Gastroenterology, College of Medicine, University of Florida. dResearch Scientist, Department of Gastroenterology, College of Medicine, University of Florida. 7/15/39199
olemic substances have also been described.6s7 Of these substances,pectin has been extensively investigated and shown to be an effective hypocholesterolemic agent with minimal side effects.7-10It has been suggestedthat pectin, like other dietary fibers, binds bile acids and thereby lowers cholesterol levels.” Previous investigators have shown that various segmentsof the vascular tree differ in their potential to develop atherosclerosis. Atheromas have been characteristically associated with large and medium systemic arteries such as the aorta, the coronary arteries, and cerebral vessels.‘*However, a hyaline type of arteriosclerosis has also been described in the arterioles of the kidneys in a human postmortem study, and this was thought to be a degenerative age change. Atherosclerosis has been induced in the oral arterial vasculature of experimental animals confined to cho351
352
PATnol. September1992
Oguntebi et al.
ORAL SURG OR.AL MED ORAL
Fig. 1. Normal dental pulp in mandibular central incisor tooth of swine on Diet 1.(Hematoxylin-eosin stain; original magnification X400.)
Table I. Percentage composition of diets
Hog Hog finisher*
Diet I Diet II Diet III
lardf (6)
Cholesterol$ (4
;
Cellulose (Alpha-cel)$ id
100 78.0 76.0
15.0 15.0
1.0 I .o
Grapefruit pectinj
-
-
-
3.0 3.0
Casing
3.84 3.84
Mineral mixturef
0.96 0.96
Vitamin mixture$
0.20 0.20
*University of Florida Swine Unit (approximately 82% corn, 15% soybean meal, 3% vitamins and minerals). tHS Camp & Son, Ocala, Fla. SIGN Biomedicals, Inc., Cleveland, Ohio §Hercules Inc., New Castle, Ind.
lesterol-supplemented diets for up to 2 years.14,l5 These studies, however, did not describe any changes in the dental pulp. Since the arteries that supply the dental pulp, like kidney glomeruli, are of arteriolar size and structure, we decided to study these vessels in an animal model of atherosclerosis. The aim of this study was to assessthe effect of hypercholesterolemia and a cholesterol-lowering diet on the dental pulp of the miniature swine. MATERIAL AND METHODS The miniature swine was selected for the study because of a close resemblance to human beings with
respect to dentition, cardiovascular system, omnivorous habits, and the tendency to develop spontaneous atherosclerosis.16Eighteen female miniature swine were used for this study. Seven swine were fed Diet I (controls-no added fat). The remaining 11 swine were given Diet II-high in fat and cholesterol (Table I)-for 390 days to establish atherosclerosis.17
These eleven swine were then randomized into two groups: one group was maintained on Diet II and the secondgroup was maintained on Diet III. These diets were continued for 326 days. Blood sampleswere taken from the animals monthly to test cholesterol and triglyceride levels. The animals were killed after 326 days by meansof intramuscular ketamine and intravenous potassium chloride injections. Biopsy specimens of the kidneys, aorta, coronary arteries, and the four mandibular incisor teeth from each animal were prepared for histopathologic examination. Block sections of the apical one third of the teeth and the surrounding alveolar bone were removed. The specimens were fixed in 10% buffered formalin for 72 hours, demineralized in 0.5% ethylenediaminetetraacetic acid, dehydrated in a graded seriesof N-butyl alcohol, and embeddedin Paraplast Plus (Sherwood Medical, St. Louis, MO.). Seven-micron transverse serial sections were prepared and stained with hematoxylin and eosin for light micros-
Hypercholesterolemia,
Volume 14 Number 3
blood vessels, dental pulp
353
Fig. 2. Normal capillary with erythrocytes in subodontoblastic layer of mandibular central incisor tooth of swine on Diet I. (Hematoxylin-eosin stain; original magnification X400.)
Table II. Cholesterol levels and vascular effects
Diet I Diet II Diet III
Total cholesterol level mg/dl
Pulpal arteriole with atheromas (%)
Pulpal arteriole narrowing (%)
Coronary artery narrowing (%)
80 f 8.2 585 + 28 455 f 31
0 9.8 2.4
0 21.07 + 4.59 16.10 2 1.72*
0 46.3 k 6.3 24.9 k 3.1*
*Significant difference from Diet II (p c 0.05).
copy with a microscope (Nikon Labophot, Nikon Inc. Instrument Group, Melville, N.Y.) fitted with a drawing tube. Ten sections from each specimen were selected from the serial sections for measurement of the percentage of cross-sectional narrowing of the pulpal arterioles by means of an Apple IIe computer (Apple Computer, Cupertino, Calif.) with morphometry software (Bioquant II, R & M Biometrics Inc., Nashville, Tenn.). The microscopic images were projected onto a digitizing tablet (resolution = 0.1 mm) after initial calibration with a stage micrometer, and measurements were made from the most central arteriole. The perimeters of the internal elastic membrane, the tunica media, and the external surface of the arterioles were measured. From these measurements, the percentage of narrowing of the arterioles was calculated. The data for the three different groups were compared by means of a Student t test. RESULTS
The 18 miniature swine remained in good health throughout the duration of the experiment. The mean initial weight of the swine was 15.9 kg, which in-
creased to a mean terminal weight of 20.3 kg. This weight increase was less dramatic in the pectintreated group (Diet III) in which the mean terminal weight was 19.2 kg. The dental pulp of the swine on Diet I (controls) was histologically normal (Fig. 1). An odontoblast layer approximately two cell layers thick was observed that reflected the location of the biopsy specimens (apical one third of the teeth). No clearly defined cell-rich or cell-poor layer was observed. The central pulp consisted of an extensive fibrous network with a few cells that were principally
fibroblasts. The
capillaries and blood vessels observed were normal (Fig. 2). The dental pulp of the swine on Diets II and III demonstrated extensive distention
of the blood
vessels(Fig. 3). Someof theseblood vesselswere filled with plasma (Fig. 4), whereas others contained eryth-
rocytes (Fig. 3). Atheromatous plaqueswere observed in 9.8% of the pulpal arterioles examined in the swine on Diet II and in 2.4% of the pulpal arterioles examined in the swine on Diet III (Fig. 5). The difference between these two groups was statistically significant (p I 0.05). Measurements of the cross-sectional nar-
354
Oguntebi et al.
Fig. 3. Dental pulp of mandibular central incisor tooth in swine on Diet II, shows distended arterioles with erythrocytes. (Hematoxylin-eosin stain; original magnification X400.)
Fig. 4. Distended plasma-filled capillary in dental pulp of mandibular central incisor tooth of hypercholesterolemic swine. (Hematoxylin-eosin stain; original magnification X400.) rowing of the central pulpal arterioles showed a mean narrowing of 2 1% in the pulpal arterioles of the swine on Diet II and a mean narrowing of 16% in the pulpal arterioles of swine on Diet III. The difference between these two means was statistically significant (p I 0.05). Histologic examination of sections prepared from the kidneys showed no connective tissue or intimal cell proliferation in the arterioles. On the other hand, the aorta and coronary arteries showed extensive atheromatous plaques and vascular narrowing in the swine on Diets II and III. The data on the aorta and coro-
nary arteries have been reported elsewhere,17 but for the purpose of comparison the data on the cross-sectional narrowing of the pulpal arterioles and coronary arteries have been combined in Table II. DISCUSSION The prevailing opinion is that systemic diseases play only a small role in the pathogenesis of pulpal pathosis.‘9M21 However, investigators have described degenerative changes in the dental pulp of older patients and it is generally assumed that these changes are a result of the aging process.19 The most striking
Volume 74 Number 3
Hypercholesterolemia,
blood vessels, dental pulp
355
Fig. 5. Atheromatous plaque in central arteriole of dental pulp of mandibular central incisor of swine on Diet III. Cross-sectional narrowing was 47.5%. (Hematoxylin-eosin stain; original magnification X400.)
change observed in the dental pulp of older subjects is the presence of dystrophic calcifications or pulp stones.20S22 Hypertension and the aging processhave been suggested as the etiologic factors that produce these changes.t9A more recent study reported a high incidence of calcifications in the dental pulp of patientswithcoronaryatherosclerosis.23Suchchanges were not observedin the teeth examined in this study, probably becauseof the short duration of the experiment and the differences in the factors examined in the two studies. However, atheromatous plaques with arteriolar narrowing were observedin a few arterioles of the dental pulp of the hypercholesterolemic swine, but no complications such as pulp calcifications were observed. The high vulnerability of oral blood vessels to atherosclerosis has been previously reported in a similar short-term experiment.‘4y I5 This high vulnerability was not confirmed for the dental pulp in this study. However, as in the previous study, the few pulpal arterioles that exhibited arteriosclerosis did not show thrombotic occlusion. The kidney biopsy material in this study did not show any hyaline arteriosclerosis similar to those previously described,t2 probably becauseof the short duration of the experiment. In contrast, the coronary arteries showed a higher degree of narrowing with some associated pathologic changes in the myocardium. The addition of grapefruit pectin to the diet caused a significant reduction in the degree of narrowing of the coronary arteries. This effect, however, was less in the pulpal arterioles. These observations suggestthat the pulpal arterioles, like renal arterioles,
are not a major target of atheromatous deposits in short-term experiments. We thank Dr. William Donelly for pathologic examination of kidney specimens,Dr. Harold Stanley for reviewing the manuscript, and Ms. Pauletta Saunders for technical assistance. REFERENCES 1. National, Heart, Lung, and Blood Institute. Report of the working group of arteriosclerosis, Vol. 2. Washington, DC: Government Printing Office; DHEW publication no. (NIH) 1981, 82-2035. 2. Ross R. The pathogenesis of atherosclerosis-an update. N Engl J Med 1986;314:488-500. 3. National Institutes of Health, Office of Medical Applications Research. Consensus conference: lowering blood cholesterol to prevent heart disease. JAMA 1985;253:2080-6. 4. Rifkind BM, ed. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering. JAMA 1984; 251136514. 5. Schaefer EJ, Levy RI. Pathogenesis and management of lipoprotein disorders. N Engl J Med 1985;312:1300-10. 6. LaFont H, Lairon D, Vigne JL, et al. Effect of wheat bran, pectin and cellulose on the secretion of bile lipids in rats. J Nutr 1985;115:849-55. 7. Keys A, Grande F, Anderson JT. Fiber and pectin in the diet and serum cholesterol concentrations in man. Proc Sot Exp Biol Med 1961;106:555-8. 8. Fisher H, Van der Noot GW, McGrath WS, Griminger P. Dietary pectin and plasma cholesterol in swine. J Atheroscler Res 1966;6:190-7. 9. Baig MM, Burgin CW, Cerda JJ. Hypocholesterolemic agents: a comparison of the relative effectiveness of cholestyramine and pectin in rats. Drug-Nutrient Interactions 1985;3:10913. 10. Baekey PA, Cerda JJ, Burgin CW, Robbins FL, Rice RW, Baumgartner TG. Grapefruit pectin inhibits hypercholesterolemia in miniature swine. Clin Cardiol 1988;11:595-600. 11. Valhouny GV, Tombe R, Cassidy ME, Kritchevsky D, Gatt
356
Oguntebi
et al.
0~41. SURGORAL Mm ORAL.PATHOL September 1992
12. 13. 14.
15.
16. 17.
18.
LL. Dietary fiber: binding of bile salts, phospholipids and cholesterol from mixed micelles by bile sequestrants and dietary fibers. Lipids 1980;15:1012-8. McGill HC, ed. General findings of the international atherosclerosis project. Lab Invest 1968;18:498-502. Smith JP. Hyaline arteriosclerosis in hypertensive and nonhypertensive individuals. J Path01 Bacterial 1955;69:147-68. Dreizen S, Stern MD, Barnet ML. Diet-induced arteriopathies in the rabbit aorta and oral vasculature. J Dent Res 1978; 57~412-7. Dreizen S, Vogel JJ, Levy BM. The effect of experimentally induced atherosclerosis on the oral structures of the rabbit. Arch Oral Biol 1971;16:43-50. Ratcliffe HL, Luginbuhl H. The domestic pig: a model for the experimental atherosclerosis. Atherosclerosis 1971;13:133-6. Cerda JJ, Robbins FL Burgin CWE, Baumgartner TC, Rice RW. The effect of grapefruit pectin on patients at risk of coronary heart diseases without altering diet or lifestyle. Clin Cardiol 1988;11:589-94. Cerda JJ, Robbins FL, Sullivan MP, Burgin CW, Normann SJ. Impact of grapefruit pectin on established atherosclerosis in microswine. Clin Res Abstr 1991;38 (M):935A.
19. Stanley HR. The effect of systemic diseases on the human pulp. In: Milton, Siskin, eds. The biology of the human dental pulp. St. Louis: CV Mosbv 1973:215-55. 20. Bernick S, Nedelman C. Effect aging on the human pulp. J Endod 1975;1:88-94. 21. Bennet CG, Kelln ED, Biddington WR. Age changes in the vascular pattern of the human dental pulp. Arch Oral Biol 1965;10:995-8. 1965;10:995-8. 22. Bernick S. Age changes in the blood supply for human teeth. J Dent Res 1967;46:544-50. 23. Moura AAM, Paiva JA. Pulpal calcifications in patients with coronary atherosclerosis. Endod Dent Traumatoll987;3:307-9. Reprint requests: Bamiduro R. Oguntehi, DDS, MS University of Florida Health Science Center Department of Endodontics P.O. Box 100436 Gainesville, FL 326 1O-0436
DDS
Department of Endodontology School of Dentistry Temple University 3223 North Broad Street Philadelphia, Pennsylvania 19140
Vascular changes in the dental pulp in the hypercholesterolemic miniature swine Bamiduro R. Oguntebi, DDS, MS,a Douglas S. Staflord, DMD,b James Cerda, IMD,~ and Frank Robbins, ~VILY,~Gainesville, Fla. UNIVERSITY
OF FLORIDA,
AND VA MEDICAL
CENTER
The aim of this study was to evaluate the effect of hypercholesterolemia and a cholesterol-lowering diet on the blood vessels of dental pulp. Eighteen miniature swine were assigned to three different groups on the basis of their diets: hog finisher; hog finisher with added fat and cholesterol, or hog finisher with added fat and cholesterol supplemented with grapefruit pectin. The cholesterol levels were monitored monthly for the duration of the experiment. Biopsy specimens of the aorta, coronary arteries, kidneys, and mandibular incisor teeth were prepared for histologic examination. The degree of narrowing of the central pulpal arterioles was measured with a Bioquant II digitizer attached to an Apple Ile computer and a Nikon Labophot light microscope. A few (9.8%) of the pulpal arterioles of the swine on a high-cholesterol diet had atheromatous plaques, but no complete vascular obstructions were observed. No degenerative changes were observed in any of the dental pulps examined. (ORAL SURG ORAL MED ORAL PATHOL 1992;74:351-6)
C
oronary heart diseaseremains the leading cause of death in the United States.’ Evidence accumulated from genetic trials, animal diet experiments, and epidemiologic studies have implicated elevated levels of circulating cholesterol as a causal factor.* Clinical trials have also shown that lowering these lipid levels by drugs and/or diet reduces the cardiovascular risk.3$4Several hypocholesteremic drugs are available in clinical practice,5 and somenatural hypocholester*Associate Professor, Department of Endodontics, College of Dentistry, University of Florida. bResident, Department of Dentistry, VA Medical Center. cProfessor, Department of Gastroenterology, College of Medicine, University of Florida. dResearch Scientist, Department of Gastroenterology, College of Medicine, University of Florida. 7/15/39199
olemic substances have also been described.6s7 Of these substances,pectin has been extensively investigated and shown to be an effective hypocholesterolemic agent with minimal side effects.7-10It has been suggestedthat pectin, like other dietary fibers, binds bile acids and thereby lowers cholesterol levels.” Previous investigators have shown that various segmentsof the vascular tree differ in their potential to develop atherosclerosis. Atheromas have been characteristically associated with large and medium systemic arteries such as the aorta, the coronary arteries, and cerebral vessels.‘*However, a hyaline type of arteriosclerosis has also been described in the arterioles of the kidneys in a human postmortem study, and this was thought to be a degenerative age change. Atherosclerosis has been induced in the oral arterial vasculature of experimental animals confined to cho351
352
PATnol. September1992
Oguntebi et al.
ORAL SURG OR.AL MED ORAL
Fig. 1. Normal dental pulp in mandibular central incisor tooth of swine on Diet 1.(Hematoxylin-eosin stain; original magnification X400.)
Table I. Percentage composition of diets
Hog Hog finisher*
Diet I Diet II Diet III
lardf (6)
Cholesterol$ (4
;
Cellulose (Alpha-cel)$ id
100 78.0 76.0
15.0 15.0
1.0 I .o
Grapefruit pectinj
-
-
-
3.0 3.0
Casing
3.84 3.84
Mineral mixturef
0.96 0.96
Vitamin mixture$
0.20 0.20
*University of Florida Swine Unit (approximately 82% corn, 15% soybean meal, 3% vitamins and minerals). tHS Camp & Son, Ocala, Fla. SIGN Biomedicals, Inc., Cleveland, Ohio §Hercules Inc., New Castle, Ind.
lesterol-supplemented diets for up to 2 years.14,l5 These studies, however, did not describe any changes in the dental pulp. Since the arteries that supply the dental pulp, like kidney glomeruli, are of arteriolar size and structure, we decided to study these vessels in an animal model of atherosclerosis. The aim of this study was to assessthe effect of hypercholesterolemia and a cholesterol-lowering diet on the dental pulp of the miniature swine. MATERIAL AND METHODS The miniature swine was selected for the study because of a close resemblance to human beings with
respect to dentition, cardiovascular system, omnivorous habits, and the tendency to develop spontaneous atherosclerosis.16Eighteen female miniature swine were used for this study. Seven swine were fed Diet I (controls-no added fat). The remaining 11 swine were given Diet II-high in fat and cholesterol (Table I)-for 390 days to establish atherosclerosis.17
These eleven swine were then randomized into two groups: one group was maintained on Diet II and the secondgroup was maintained on Diet III. These diets were continued for 326 days. Blood sampleswere taken from the animals monthly to test cholesterol and triglyceride levels. The animals were killed after 326 days by meansof intramuscular ketamine and intravenous potassium chloride injections. Biopsy specimens of the kidneys, aorta, coronary arteries, and the four mandibular incisor teeth from each animal were prepared for histopathologic examination. Block sections of the apical one third of the teeth and the surrounding alveolar bone were removed. The specimens were fixed in 10% buffered formalin for 72 hours, demineralized in 0.5% ethylenediaminetetraacetic acid, dehydrated in a graded seriesof N-butyl alcohol, and embeddedin Paraplast Plus (Sherwood Medical, St. Louis, MO.). Seven-micron transverse serial sections were prepared and stained with hematoxylin and eosin for light micros-
Hypercholesterolemia,
Volume 14 Number 3
blood vessels, dental pulp
353
Fig. 2. Normal capillary with erythrocytes in subodontoblastic layer of mandibular central incisor tooth of swine on Diet I. (Hematoxylin-eosin stain; original magnification X400.)
Table II. Cholesterol levels and vascular effects
Diet I Diet II Diet III
Total cholesterol level mg/dl
Pulpal arteriole with atheromas (%)
Pulpal arteriole narrowing (%)
Coronary artery narrowing (%)
80 f 8.2 585 + 28 455 f 31
0 9.8 2.4
0 21.07 + 4.59 16.10 2 1.72*
0 46.3 k 6.3 24.9 k 3.1*
*Significant difference from Diet II (p c 0.05).
copy with a microscope (Nikon Labophot, Nikon Inc. Instrument Group, Melville, N.Y.) fitted with a drawing tube. Ten sections from each specimen were selected from the serial sections for measurement of the percentage of cross-sectional narrowing of the pulpal arterioles by means of an Apple IIe computer (Apple Computer, Cupertino, Calif.) with morphometry software (Bioquant II, R & M Biometrics Inc., Nashville, Tenn.). The microscopic images were projected onto a digitizing tablet (resolution = 0.1 mm) after initial calibration with a stage micrometer, and measurements were made from the most central arteriole. The perimeters of the internal elastic membrane, the tunica media, and the external surface of the arterioles were measured. From these measurements, the percentage of narrowing of the arterioles was calculated. The data for the three different groups were compared by means of a Student t test. RESULTS
The 18 miniature swine remained in good health throughout the duration of the experiment. The mean initial weight of the swine was 15.9 kg, which in-
creased to a mean terminal weight of 20.3 kg. This weight increase was less dramatic in the pectintreated group (Diet III) in which the mean terminal weight was 19.2 kg. The dental pulp of the swine on Diet I (controls) was histologically normal (Fig. 1). An odontoblast layer approximately two cell layers thick was observed that reflected the location of the biopsy specimens (apical one third of the teeth). No clearly defined cell-rich or cell-poor layer was observed. The central pulp consisted of an extensive fibrous network with a few cells that were principally
fibroblasts. The
capillaries and blood vessels observed were normal (Fig. 2). The dental pulp of the swine on Diets II and III demonstrated extensive distention
of the blood
vessels(Fig. 3). Someof theseblood vesselswere filled with plasma (Fig. 4), whereas others contained eryth-
rocytes (Fig. 3). Atheromatous plaqueswere observed in 9.8% of the pulpal arterioles examined in the swine on Diet II and in 2.4% of the pulpal arterioles examined in the swine on Diet III (Fig. 5). The difference between these two groups was statistically significant (p I 0.05). Measurements of the cross-sectional nar-
354
Oguntebi et al.
Fig. 3. Dental pulp of mandibular central incisor tooth in swine on Diet II, shows distended arterioles with erythrocytes. (Hematoxylin-eosin stain; original magnification X400.)
Fig. 4. Distended plasma-filled capillary in dental pulp of mandibular central incisor tooth of hypercholesterolemic swine. (Hematoxylin-eosin stain; original magnification X400.) rowing of the central pulpal arterioles showed a mean narrowing of 2 1% in the pulpal arterioles of the swine on Diet II and a mean narrowing of 16% in the pulpal arterioles of swine on Diet III. The difference between these two means was statistically significant (p I 0.05). Histologic examination of sections prepared from the kidneys showed no connective tissue or intimal cell proliferation in the arterioles. On the other hand, the aorta and coronary arteries showed extensive atheromatous plaques and vascular narrowing in the swine on Diets II and III. The data on the aorta and coro-
nary arteries have been reported elsewhere,17 but for the purpose of comparison the data on the cross-sectional narrowing of the pulpal arterioles and coronary arteries have been combined in Table II. DISCUSSION The prevailing opinion is that systemic diseases play only a small role in the pathogenesis of pulpal pathosis.‘9M21 However, investigators have described degenerative changes in the dental pulp of older patients and it is generally assumed that these changes are a result of the aging process.19 The most striking
Volume 74 Number 3
Hypercholesterolemia,
blood vessels, dental pulp
355
Fig. 5. Atheromatous plaque in central arteriole of dental pulp of mandibular central incisor of swine on Diet III. Cross-sectional narrowing was 47.5%. (Hematoxylin-eosin stain; original magnification X400.)
change observed in the dental pulp of older subjects is the presence of dystrophic calcifications or pulp stones.20S22 Hypertension and the aging processhave been suggested as the etiologic factors that produce these changes.t9A more recent study reported a high incidence of calcifications in the dental pulp of patientswithcoronaryatherosclerosis.23Suchchanges were not observedin the teeth examined in this study, probably becauseof the short duration of the experiment and the differences in the factors examined in the two studies. However, atheromatous plaques with arteriolar narrowing were observedin a few arterioles of the dental pulp of the hypercholesterolemic swine, but no complications such as pulp calcifications were observed. The high vulnerability of oral blood vessels to atherosclerosis has been previously reported in a similar short-term experiment.‘4y I5 This high vulnerability was not confirmed for the dental pulp in this study. However, as in the previous study, the few pulpal arterioles that exhibited arteriosclerosis did not show thrombotic occlusion. The kidney biopsy material in this study did not show any hyaline arteriosclerosis similar to those previously described,t2 probably becauseof the short duration of the experiment. In contrast, the coronary arteries showed a higher degree of narrowing with some associated pathologic changes in the myocardium. The addition of grapefruit pectin to the diet caused a significant reduction in the degree of narrowing of the coronary arteries. This effect, however, was less in the pulpal arterioles. These observations suggestthat the pulpal arterioles, like renal arterioles,
are not a major target of atheromatous deposits in short-term experiments. We thank Dr. William Donelly for pathologic examination of kidney specimens,Dr. Harold Stanley for reviewing the manuscript, and Ms. Pauletta Saunders for technical assistance. REFERENCES 1. National, Heart, Lung, and Blood Institute. Report of the working group of arteriosclerosis, Vol. 2. Washington, DC: Government Printing Office; DHEW publication no. (NIH) 1981, 82-2035. 2. Ross R. The pathogenesis of atherosclerosis-an update. N Engl J Med 1986;314:488-500. 3. National Institutes of Health, Office of Medical Applications Research. Consensus conference: lowering blood cholesterol to prevent heart disease. JAMA 1985;253:2080-6. 4. Rifkind BM, ed. The relationship of reduction in incidence of coronary heart disease to cholesterol lowering. JAMA 1984; 251136514. 5. Schaefer EJ, Levy RI. Pathogenesis and management of lipoprotein disorders. N Engl J Med 1985;312:1300-10. 6. LaFont H, Lairon D, Vigne JL, et al. Effect of wheat bran, pectin and cellulose on the secretion of bile lipids in rats. J Nutr 1985;115:849-55. 7. Keys A, Grande F, Anderson JT. Fiber and pectin in the diet and serum cholesterol concentrations in man. Proc Sot Exp Biol Med 1961;106:555-8. 8. Fisher H, Van der Noot GW, McGrath WS, Griminger P. Dietary pectin and plasma cholesterol in swine. J Atheroscler Res 1966;6:190-7. 9. Baig MM, Burgin CW, Cerda JJ. Hypocholesterolemic agents: a comparison of the relative effectiveness of cholestyramine and pectin in rats. Drug-Nutrient Interactions 1985;3:10913. 10. Baekey PA, Cerda JJ, Burgin CW, Robbins FL, Rice RW, Baumgartner TG. Grapefruit pectin inhibits hypercholesterolemia in miniature swine. Clin Cardiol 1988;11:595-600. 11. Valhouny GV, Tombe R, Cassidy ME, Kritchevsky D, Gatt
356
Oguntebi
et al.
0~41. SURGORAL Mm ORAL.PATHOL September 1992
12. 13. 14.
15.
16. 17.
18.
LL. Dietary fiber: binding of bile salts, phospholipids and cholesterol from mixed micelles by bile sequestrants and dietary fibers. Lipids 1980;15:1012-8. McGill HC, ed. General findings of the international atherosclerosis project. Lab Invest 1968;18:498-502. Smith JP. Hyaline arteriosclerosis in hypertensive and nonhypertensive individuals. J Path01 Bacterial 1955;69:147-68. Dreizen S, Stern MD, Barnet ML. Diet-induced arteriopathies in the rabbit aorta and oral vasculature. J Dent Res 1978; 57~412-7. Dreizen S, Vogel JJ, Levy BM. The effect of experimentally induced atherosclerosis on the oral structures of the rabbit. Arch Oral Biol 1971;16:43-50. Ratcliffe HL, Luginbuhl H. The domestic pig: a model for the experimental atherosclerosis. Atherosclerosis 1971;13:133-6. Cerda JJ, Robbins FL Burgin CWE, Baumgartner TC, Rice RW. The effect of grapefruit pectin on patients at risk of coronary heart diseases without altering diet or lifestyle. Clin Cardiol 1988;11:589-94. Cerda JJ, Robbins FL, Sullivan MP, Burgin CW, Normann SJ. Impact of grapefruit pectin on established atherosclerosis in microswine. Clin Res Abstr 1991;38 (M):935A.
19. Stanley HR. The effect of systemic diseases on the human pulp. In: Milton, Siskin, eds. The biology of the human dental pulp. St. Louis: CV Mosbv 1973:215-55. 20. Bernick S, Nedelman C. Effect aging on the human pulp. J Endod 1975;1:88-94. 21. Bennet CG, Kelln ED, Biddington WR. Age changes in the vascular pattern of the human dental pulp. Arch Oral Biol 1965;10:995-8. 1965;10:995-8. 22. Bernick S. Age changes in the blood supply for human teeth. J Dent Res 1967;46:544-50. 23. Moura AAM, Paiva JA. Pulpal calcifications in patients with coronary atherosclerosis. Endod Dent Traumatoll987;3:307-9. Reprint requests: Bamiduro R. Oguntehi, DDS, MS University of Florida Health Science Center Department of Endodontics P.O. Box 100436 Gainesville, FL 326 1O-0436
