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Vascular changes after experimentally-induced inflammation in the mandible
Vascular changes after experi mentally-induced inflammation in the mandible
Karin Wannfors Department of Oral Pathology, School of Dentistry, Karolinska Institutet, Stockholm, Sweden
K. Wannfors: Vascular changes after experimentally-induced inflammation in the mandible. Int. J. Oral Maxillofac. Surg. 1989; 18: 79-82. Abstract. In this study, the vascular supply of an experimentally-induced inflammatory reaction in 5 monkey mandibles is examined. A barium sulfate injection method, combined with contact microradiography was used. In all monkeys, marked vascular changes were seen within the areas of inflammation. Vertical nutrient branches were interrupted shortly after leaving the inferior alveolar artery, and a conglomerate of thin irregular vessels were seen interspersed through newly formed bone trabeculae. The vascular supply to the neighbouring teeth seemed to be unaltered; neither was there any evidence of vascular thrombosis or vasculitis.
Hematogenous spread of bacteria and spread from a local focus are the 2 mayor mechanisms of infectious inoculation in osteomyelitis. Irrespective of the pathway of infection, patients suffering from diseases affecting the blood vessels such as diabetes, rheumatoid vasculitis, and sickle cell anemia, are
predisposed to develope osteomyelitis5, 6, 11 13. Local vascular infirmities, such as the connections between arteries and venules in the metaphyseal-epiphysealregion of the long bones also increase the risk of development of osteomyelitis1,4. 6, 12, 14 Once established, osteomyelitis in its
Key words: vascular changes; experimental inflammation; osteomyelitis. Accepted for publication 22 October 1988
turn causes changes in the vascular supply. On the one hand, inflammatory changes within the blood vessels may facilitate the deposit of bacteria along the walls of the vessels, sometimes leading to vascular thrombosis or thrombophlebitis. On the other hand, the inflammation itself, without the concomittant spread of bacteria, compromises the blood supply, increasing the risk of inschaemic necrosis of bone 2' 5,8. The aim of the present study was to examine the microvascular supply of experimentally-induced inflammation in bone, to reveal abnormal vascular patterns as compared to that of normal bone, and to look for signs of vascular thrombosis or vasculitis. Material and methods
Fig. 1. Angiograph showing the physiologicalextension of the vascular network of the monkey mandible. Note the inferior alveolar artery (major arrow) near the upper border of the mandibular canal. Verticalbranches (minor arrow) leave the main artery in a direction towards the alveolar crest.
5 monkeys (Macaca fascicularis) were used in this experiment. All surgical procedures were carried out under general anaesthesia. Intra muscular injection of Ketaminechloride (Ketalar-R, Parke-Davies & Co., U.K.) was used for those procedures that required only a stort anaesthesia, while intravenous administration of 6% sodium pentobarbital (Nembutal®,Abbot, Stockholm, Sweden)was used for anaesthesia during the final perfusion procedure. All monkeys had the crowns of their lateral maxillary incisors opened from the buccal aspect. Plaque material, gathered
80
Wannfors
from the lingual aspect of the mandibular incisors, was inserted into the bleeding pulp tissue. The cavities were then sealed with zinc oxide and eugenol cement. After 3 weeks, all monkeys had their infected incisors removed as well as their 2nd right mandibular premolar teeth. The premolar sockets were deepened, using a round bur, to the level of the mandibular canal. The apical halves of the infected right maxillary incisors were planted into the prepared sites, and covered by a tightly sutured oral mucosa. After 6 months, the common carotid carteries were bilaterally exposed and cannulated. The vascular bed was then flushed with heparinized saline (1000 IE/ml), followed by perfusion with wanla (37°C) aqueous barium sulfate solution (60% Micropaque®, Nicholas, Slough, Bucks, England, and 40% saline). The injection was performed simultaneously through the carotid arteries, with the injection pressure slightly above the systolic blood pressure (170 mm Hg). Adequate filling was indicated by profuse color changes within the oral tissues. The jugular veins were then opened. When barium sulphate appeared through the jugular veins, the saline compound was exchanged by 10% formalin. The perfusion was continued until muscle fasciculation was noted. The mandibles were excised and split in the midline. Radiographs were taken from the dissected jaws. The mandibles were then kept in 10% formalin for 48 h for supplementary fixation. After demineralization in 20% formic acid, the mandibles were cut in 3 mm thick slices by means of a scalpel. The direction was perpendicular to the long axis of the mandibular body, and efforts were made to cut the right and the left mandibles in the
Fig. 3. Microantiograph showing the physiological vascular pattern of the 2nd premolar tooth and the surrounding alveolar bone, seen in a transverse projection. The vertical main branches are seen leaving the inferior alveolar artery. A few collateral branches are seen penetrating the large marrow space (arrow) in the center of the mandibular body, while the main vessels can be followed to the alevolar crest.
Fig. 2. (a) Microangiograph. Transverse section of the left mandibular canine region, exploring the physiological vascular orientation in the area. Vertical main vessels branch off to supply the cancellous bone, the pulp of a tooth and the periodontium. (b) Microscopic photograph of an artery filled with contrast medium (a) and sombe empty thin walled veins (v) (H & E x 160).
Vascular changes in inflamed bone
81
Fig. 4. (a) Microangiograph showing the pathological vascular condition of the inflamed bone of the right first premolar area. (b) Microangiograph showing the pathological interruption of the main vertical nutrient vessels (vb) shortly after leaving the inferior alveolar artery (ia). In the middle of the mandibular body, a conglomerate of thin vessels is seen. In spite of the changed vascular pattern, the vascular nutrition of the premolar tooth does not seem to be disturbed (arrow).
same manner. The sections were passed through increasing concentrations of ethanol and embedded in a thin layer of paraffin wax. Contact micr0radiographs were made using Philip's X-ray diffraction tube PW 2223/20 and Kodak high-resolution plates. The target to film distance was 15 cm' and the average exposure time 20 min. When the microradiographic procedure was completed, the embedded bone slices were prepared for histology. Results
The roentgenographs taken immediately after the dissecting procedure of the mandibles, showed that the contrast medium had been distributed in the whole area (Fig. 1). The microradiograms and the microscopic examination showed that all nutrient vessels, including the arterioles were filled with contrast medium while the venules were empty or only partly filled with contrast medium. In some sections erythrocytes were seen in the venules. There were no
signs of ruptured vessels or particles of the contrast medium discharged into the tissue (Fig. 2). The general vascular pattern was similar in all monkeys. The main alveolar artery and its concomittant veins were seen in cross sections. Buccal and lingual main branches could be followed vertically from where they branched off the main artery towards the alveolar crest. In the posterior parts of the mandibles, the inferior alveolar artery was seen in the center of the alveolar body, while it was found near the base and further buccally in the intermediate parts of the mandibles. Anterior to the mental foramina, the main artery had branched off the mental artery and divided further. The vertical main branches divided further up to supply the cancellous bone, the periodontal tissue, the pulps of the teeth and parts of the gingiva. Vessels supplying the cancellous bone mostly followed the trabeculae.
A few vessels were seen penetrating the marrow spaces (Fig. 3). The roentgenograms of the whole mandibles showed dramatically changed vascular patterns in the right premolar areas, where the infected dental roots had been implanted. A proliferating network of apparently randomly oriented thin vessels were seen interspersed throughout the newly formed bone trabeculae. The microradiograms showed that the buccal and lingual vertical main branches were interrupted shortly after leaving the main alveolar artery. Some of them could not be detected at all. However, the vascular supply to the neighbouring teeth seemed to be unaltered. The microradiograms did not reveal any evidence of blocking of the main alveolar artery or other main nutrient vessels (Fig. 4). Histological examination confirmed the impression of vascular disorder with a dramatic increase of small nutrient vessels, but no signs
82
Wannfors
secondary infection. It is most likely, among other factors, that this phenomenon plays a r61e in the origin of osteomyelitis of the jaws.
References
Fig. 5. Microscopic photograph of the inflamed bone tissue. Lymphocytes and plasma cells were often concentrated in the immediate surroundings of the vessels and their concomitant nerves. Note lymphocytes migrating through the leaking wall of the vessel (arrow) (H & E x 400).
of vascular thrombosis or inflammatory changes within the walls of the vessels were observed, although pools of lymphocytes and plasma cells were frequently seen in the immediate surroundings of the capillaries (Fig. 5). Discussion
The microradiograms as well as the histological slides showed that the capillaries of the arterial side were filled with contrast medium, while the venules were empty or only partly filled. The reason for this is the particle size of the contrast medium (Micropaque®), which is just smaller than the capillary diameter9' 10. Thus, a resistance is built up in the capillary system which minimizes the risk of poor filling of afferent vessels. The histological studies did not reveal any signs of ruptured vessels or discharged contrast medium between the vessels, indicating that the technique used during the perfusion procedure had overcome the problems with overfilling. The microradiograms revealed a dramatic increase in small vessels, proliferating through the inflamed bone. These findings were confirmed by histological studies of the same areas. The
vertical arteries seemed to be interrupted when they were entering areas of inflamed bone. They split up into a poorly orientated network of small capillaries, resulting in a reduced flow of blood. In spite of the interrupted main artery, circulation in the pulps of the neighbouring teeth did not seem to be disturbed, probably thanks to spontaneous anastomoses with other areas of the vascular bed. The microangiographic technique reveals whether tissue is supplied by blood or not, but the technique cannot be used as a basis for an estimation of the flow of blood. However, it is known from studies on pulp tissue that there is an increased capillary pressure due to precapillary dilatation in inflamed tissue. The tissue fluid colloid osmotic pressure is raised, caused by inflammatory-induced, increased capillary premeability. Both of these forces favour filtration, and result in net filtration of fluid into the tissues2. Since the compliance of the marrow spaces in the mandible is comparable to that of the dental pulp, the tissue pressure in the mandible may secondarily affect flow in areas previously not involved in the inflammatory process, resulting in imparired nutrition of a large area of bone, predisposing it to
1. Gilhus-Moe, O.: Osteomyelitt. In: Hjorting-Hansen, E., Nordenram, A., Aas, E. (eds.): Oral kirurgi 1st edition 1977, pp. 192-206. 2. Heyeraas, K. J.: Pulpal, microvascular and tissue pressure. J. Dent. Res. 1985: 64: 585-589. 3. Jacobsson, S.: Diffuse scleroring osteomyelitis of the mandible. Int. J. Oral Surg. 1984: 13: 363-385. 4. Marx, R. E. & Johnson, R. E: Studies in the radiobiology of osteoradionecrosis and their clinical significance. Oral Surg. 1987: 64: 379-390. 5. Nelson, L. & Lydiatt, D.: Osteomyelitis of the head and neck. The Nebr. Med. Journ. 1987: 72: 154-162. 6. Raft, M. J. & Melt, J. C.: Anaerobic osteomyelitis. Medicine 1978: 57: 89103. 7. Revelt, R: Infection of bone. In: Revell, R (ed.): Pathology of bone, 1st edition. Springer Verlag. Berlin, Heidelberg, 1986, pp. 235 245. 8. Robbins, S. L., Cotran, R. S. & Dumar, V.: Pathologic basis of disease 3rd edition. W. B. Saunders Company, Philadelphia 1984, pp. 40-69. 9. Rubin, P. J.: Microangiography - facts and artifacts. Radial Clin. North. 1964: 2: 449-451. 10. Skoglund, A., Tronstad, L. & Wallenius, K.: A micrographic study of vascular changes. Oral Surg. 1978: 45: 17-28. 11. Wald, E.: Risk factors for osteomyelitis. The Am. Journ. of Med. 1985: 78: 206212. 12. Waldvogel, F., Medaff, G. & Swartz, M.: Osteomyelitis: a review of clinical features, therapeutic considerations and unusual aspects. New Engl. J. Med. 1970: 22: 198-206, 260-266, 316-322. 13. Weinstein, A.: Osteomyelitis. Primary Care 1981: 8: 557-569. 14. Wood, N., Goaz, P. & Stuteville, O.: Solitary radiolucencies with ragged and poorly defined borders. Differential diagnoses of oral lesions. C. V. Mosby Company 1985, pp. 440-446. Address: K. Wannfors Department of Oral Pathology School of Dentistry Karolinska Institutet Stockholm Sweden
Karin Wannfors Department of Oral Pathology, School of Dentistry, Karolinska Institutet, Stockholm, Sweden
K. Wannfors: Vascular changes after experimentally-induced inflammation in the mandible. Int. J. Oral Maxillofac. Surg. 1989; 18: 79-82. Abstract. In this study, the vascular supply of an experimentally-induced inflammatory reaction in 5 monkey mandibles is examined. A barium sulfate injection method, combined with contact microradiography was used. In all monkeys, marked vascular changes were seen within the areas of inflammation. Vertical nutrient branches were interrupted shortly after leaving the inferior alveolar artery, and a conglomerate of thin irregular vessels were seen interspersed through newly formed bone trabeculae. The vascular supply to the neighbouring teeth seemed to be unaltered; neither was there any evidence of vascular thrombosis or vasculitis.
Hematogenous spread of bacteria and spread from a local focus are the 2 mayor mechanisms of infectious inoculation in osteomyelitis. Irrespective of the pathway of infection, patients suffering from diseases affecting the blood vessels such as diabetes, rheumatoid vasculitis, and sickle cell anemia, are
predisposed to develope osteomyelitis5, 6, 11 13. Local vascular infirmities, such as the connections between arteries and venules in the metaphyseal-epiphysealregion of the long bones also increase the risk of development of osteomyelitis1,4. 6, 12, 14 Once established, osteomyelitis in its
Key words: vascular changes; experimental inflammation; osteomyelitis. Accepted for publication 22 October 1988
turn causes changes in the vascular supply. On the one hand, inflammatory changes within the blood vessels may facilitate the deposit of bacteria along the walls of the vessels, sometimes leading to vascular thrombosis or thrombophlebitis. On the other hand, the inflammation itself, without the concomittant spread of bacteria, compromises the blood supply, increasing the risk of inschaemic necrosis of bone 2' 5,8. The aim of the present study was to examine the microvascular supply of experimentally-induced inflammation in bone, to reveal abnormal vascular patterns as compared to that of normal bone, and to look for signs of vascular thrombosis or vasculitis. Material and methods
Fig. 1. Angiograph showing the physiologicalextension of the vascular network of the monkey mandible. Note the inferior alveolar artery (major arrow) near the upper border of the mandibular canal. Verticalbranches (minor arrow) leave the main artery in a direction towards the alveolar crest.
5 monkeys (Macaca fascicularis) were used in this experiment. All surgical procedures were carried out under general anaesthesia. Intra muscular injection of Ketaminechloride (Ketalar-R, Parke-Davies & Co., U.K.) was used for those procedures that required only a stort anaesthesia, while intravenous administration of 6% sodium pentobarbital (Nembutal®,Abbot, Stockholm, Sweden)was used for anaesthesia during the final perfusion procedure. All monkeys had the crowns of their lateral maxillary incisors opened from the buccal aspect. Plaque material, gathered
80
Wannfors
from the lingual aspect of the mandibular incisors, was inserted into the bleeding pulp tissue. The cavities were then sealed with zinc oxide and eugenol cement. After 3 weeks, all monkeys had their infected incisors removed as well as their 2nd right mandibular premolar teeth. The premolar sockets were deepened, using a round bur, to the level of the mandibular canal. The apical halves of the infected right maxillary incisors were planted into the prepared sites, and covered by a tightly sutured oral mucosa. After 6 months, the common carotid carteries were bilaterally exposed and cannulated. The vascular bed was then flushed with heparinized saline (1000 IE/ml), followed by perfusion with wanla (37°C) aqueous barium sulfate solution (60% Micropaque®, Nicholas, Slough, Bucks, England, and 40% saline). The injection was performed simultaneously through the carotid arteries, with the injection pressure slightly above the systolic blood pressure (170 mm Hg). Adequate filling was indicated by profuse color changes within the oral tissues. The jugular veins were then opened. When barium sulphate appeared through the jugular veins, the saline compound was exchanged by 10% formalin. The perfusion was continued until muscle fasciculation was noted. The mandibles were excised and split in the midline. Radiographs were taken from the dissected jaws. The mandibles were then kept in 10% formalin for 48 h for supplementary fixation. After demineralization in 20% formic acid, the mandibles were cut in 3 mm thick slices by means of a scalpel. The direction was perpendicular to the long axis of the mandibular body, and efforts were made to cut the right and the left mandibles in the
Fig. 3. Microantiograph showing the physiological vascular pattern of the 2nd premolar tooth and the surrounding alveolar bone, seen in a transverse projection. The vertical main branches are seen leaving the inferior alveolar artery. A few collateral branches are seen penetrating the large marrow space (arrow) in the center of the mandibular body, while the main vessels can be followed to the alevolar crest.
Fig. 2. (a) Microangiograph. Transverse section of the left mandibular canine region, exploring the physiological vascular orientation in the area. Vertical main vessels branch off to supply the cancellous bone, the pulp of a tooth and the periodontium. (b) Microscopic photograph of an artery filled with contrast medium (a) and sombe empty thin walled veins (v) (H & E x 160).
Vascular changes in inflamed bone
81
Fig. 4. (a) Microangiograph showing the pathological vascular condition of the inflamed bone of the right first premolar area. (b) Microangiograph showing the pathological interruption of the main vertical nutrient vessels (vb) shortly after leaving the inferior alveolar artery (ia). In the middle of the mandibular body, a conglomerate of thin vessels is seen. In spite of the changed vascular pattern, the vascular nutrition of the premolar tooth does not seem to be disturbed (arrow).
same manner. The sections were passed through increasing concentrations of ethanol and embedded in a thin layer of paraffin wax. Contact micr0radiographs were made using Philip's X-ray diffraction tube PW 2223/20 and Kodak high-resolution plates. The target to film distance was 15 cm' and the average exposure time 20 min. When the microradiographic procedure was completed, the embedded bone slices were prepared for histology. Results
The roentgenographs taken immediately after the dissecting procedure of the mandibles, showed that the contrast medium had been distributed in the whole area (Fig. 1). The microradiograms and the microscopic examination showed that all nutrient vessels, including the arterioles were filled with contrast medium while the venules were empty or only partly filled with contrast medium. In some sections erythrocytes were seen in the venules. There were no
signs of ruptured vessels or particles of the contrast medium discharged into the tissue (Fig. 2). The general vascular pattern was similar in all monkeys. The main alveolar artery and its concomittant veins were seen in cross sections. Buccal and lingual main branches could be followed vertically from where they branched off the main artery towards the alveolar crest. In the posterior parts of the mandibles, the inferior alveolar artery was seen in the center of the alveolar body, while it was found near the base and further buccally in the intermediate parts of the mandibles. Anterior to the mental foramina, the main artery had branched off the mental artery and divided further. The vertical main branches divided further up to supply the cancellous bone, the periodontal tissue, the pulps of the teeth and parts of the gingiva. Vessels supplying the cancellous bone mostly followed the trabeculae.
A few vessels were seen penetrating the marrow spaces (Fig. 3). The roentgenograms of the whole mandibles showed dramatically changed vascular patterns in the right premolar areas, where the infected dental roots had been implanted. A proliferating network of apparently randomly oriented thin vessels were seen interspersed throughout the newly formed bone trabeculae. The microradiograms showed that the buccal and lingual vertical main branches were interrupted shortly after leaving the main alveolar artery. Some of them could not be detected at all. However, the vascular supply to the neighbouring teeth seemed to be unaltered. The microradiograms did not reveal any evidence of blocking of the main alveolar artery or other main nutrient vessels (Fig. 4). Histological examination confirmed the impression of vascular disorder with a dramatic increase of small nutrient vessels, but no signs
82
Wannfors
secondary infection. It is most likely, among other factors, that this phenomenon plays a r61e in the origin of osteomyelitis of the jaws.
References
Fig. 5. Microscopic photograph of the inflamed bone tissue. Lymphocytes and plasma cells were often concentrated in the immediate surroundings of the vessels and their concomitant nerves. Note lymphocytes migrating through the leaking wall of the vessel (arrow) (H & E x 400).
of vascular thrombosis or inflammatory changes within the walls of the vessels were observed, although pools of lymphocytes and plasma cells were frequently seen in the immediate surroundings of the capillaries (Fig. 5). Discussion
The microradiograms as well as the histological slides showed that the capillaries of the arterial side were filled with contrast medium, while the venules were empty or only partly filled. The reason for this is the particle size of the contrast medium (Micropaque®), which is just smaller than the capillary diameter9' 10. Thus, a resistance is built up in the capillary system which minimizes the risk of poor filling of afferent vessels. The histological studies did not reveal any signs of ruptured vessels or discharged contrast medium between the vessels, indicating that the technique used during the perfusion procedure had overcome the problems with overfilling. The microradiograms revealed a dramatic increase in small vessels, proliferating through the inflamed bone. These findings were confirmed by histological studies of the same areas. The
vertical arteries seemed to be interrupted when they were entering areas of inflamed bone. They split up into a poorly orientated network of small capillaries, resulting in a reduced flow of blood. In spite of the interrupted main artery, circulation in the pulps of the neighbouring teeth did not seem to be disturbed, probably thanks to spontaneous anastomoses with other areas of the vascular bed. The microangiographic technique reveals whether tissue is supplied by blood or not, but the technique cannot be used as a basis for an estimation of the flow of blood. However, it is known from studies on pulp tissue that there is an increased capillary pressure due to precapillary dilatation in inflamed tissue. The tissue fluid colloid osmotic pressure is raised, caused by inflammatory-induced, increased capillary premeability. Both of these forces favour filtration, and result in net filtration of fluid into the tissues2. Since the compliance of the marrow spaces in the mandible is comparable to that of the dental pulp, the tissue pressure in the mandible may secondarily affect flow in areas previously not involved in the inflammatory process, resulting in imparired nutrition of a large area of bone, predisposing it to
1. Gilhus-Moe, O.: Osteomyelitt. In: Hjorting-Hansen, E., Nordenram, A., Aas, E. (eds.): Oral kirurgi 1st edition 1977, pp. 192-206. 2. Heyeraas, K. J.: Pulpal, microvascular and tissue pressure. J. Dent. Res. 1985: 64: 585-589. 3. Jacobsson, S.: Diffuse scleroring osteomyelitis of the mandible. Int. J. Oral Surg. 1984: 13: 363-385. 4. Marx, R. E. & Johnson, R. E: Studies in the radiobiology of osteoradionecrosis and their clinical significance. Oral Surg. 1987: 64: 379-390. 5. Nelson, L. & Lydiatt, D.: Osteomyelitis of the head and neck. The Nebr. Med. Journ. 1987: 72: 154-162. 6. Raft, M. J. & Melt, J. C.: Anaerobic osteomyelitis. Medicine 1978: 57: 89103. 7. Revelt, R: Infection of bone. In: Revell, R (ed.): Pathology of bone, 1st edition. Springer Verlag. Berlin, Heidelberg, 1986, pp. 235 245. 8. Robbins, S. L., Cotran, R. S. & Dumar, V.: Pathologic basis of disease 3rd edition. W. B. Saunders Company, Philadelphia 1984, pp. 40-69. 9. Rubin, P. J.: Microangiography - facts and artifacts. Radial Clin. North. 1964: 2: 449-451. 10. Skoglund, A., Tronstad, L. & Wallenius, K.: A micrographic study of vascular changes. Oral Surg. 1978: 45: 17-28. 11. Wald, E.: Risk factors for osteomyelitis. The Am. Journ. of Med. 1985: 78: 206212. 12. Waldvogel, F., Medaff, G. & Swartz, M.: Osteomyelitis: a review of clinical features, therapeutic considerations and unusual aspects. New Engl. J. Med. 1970: 22: 198-206, 260-266, 316-322. 13. Weinstein, A.: Osteomyelitis. Primary Care 1981: 8: 557-569. 14. Wood, N., Goaz, P. & Stuteville, O.: Solitary radiolucencies with ragged and poorly defined borders. Differential diagnoses of oral lesions. C. V. Mosby Company 1985, pp. 440-446. Address: K. Wannfors Department of Oral Pathology School of Dentistry Karolinska Institutet Stockholm Sweden