J Oral Maxlllofac
Surg
49.1305-1309.1991
Evaluation of a Bone Substitute Prepared From a-Tricalcium Phosphate and an Acid Polysaccharide Solution MAMORU
NAGASE, DDS, PHD,* RUEY-BIN CHEN, DDS, PiiD,+ YUMl ARAYA, DDS,t AND TAM10 NAKAJIMA, DDS, PHD$
Tissue response to a readily consolidating material prepared by mixing cw-tricalcium phosphate (wTCP) powder with a glycolic acid dextran solution and to this consolidating material combined with particulate hydroxylapatite (HA) was studied after implantation in the subperiosteal space of the mandible in rabbits. Active new bone formation comparable to that seen on HA implants was observed around the two compounds. The newly formed bone was in direct contact with the HA as well as the readily consolidated material and little adverse effect resulting from the glycolic acid and dextran was observed. Because the readily consolidating material was firm and could be countoured into any shape during the process of consolidation, it may be quite useful as a bone substitute and as an adherent for HA particles for reconstructive bone surgery, overcoming the disadvantages inherent to the particulate form of HA.
Materials and Methods
Particulate hydroxylapatite (HA) is widely used for alveolar ridge augmentation of atrophic jaws. The difficulty in delivering the material in a proper location and the lack of adhesiveness and plasticity are problems inherent to the particulate form of HA. A readily consolidating bone substitute would be very useful for alveolar ridge augmentation and reconstructive surgery of bone. In this report, the tissue response to a readily consolidating material prepared by mixing a-TCP and an acid-polysaccharide solution and to this material combined with particulate HA was studied in rabbits.
Glycolic acid was dissolved in distilled water (w/v = 30%), and dextran (molecular weight, 60,000 to 90,000) was added (dextran:solution = 5:4), to produce a viscous acid polysaccharide solution. As shown in Figure 1, the mixture of a-TCP powder with a particle size ranging from 6 to 20 km in diameter (Sankin Kogyo Co Ltd, Tokyo) and the acid polysaccharide solution (powder:solution = 5:7) consolidated in about 2 to 5 minutes to produce a block that was firm, but slightly bendable on thinning (TCP implant). A mixture of wTCP powder and HA particles and the acid-polysaccaharide solution (TCP: HA: solution = 5: 10:7), which became consolidated in about 2 to 5 minutes, was also used to produce a block (TCP-HA implant). The TCP implant was adjusted to the bone surface during the process of consolidation and was implanted within 2 minutes after mixing into the subperiosteal space of the mandible in 14 rabbits as described in a previous article.’ The TCP-HA implant was implanted into eight rabbits 15 minutes after mixing. Four shamoperated rabbits served as the control.
Received from the First Department of Oral and Maxillofacial Surgery, School of Dentistry, Niigata University, Niigata City, Japan. * Fulltime Lecturer. t Resident. $ Professor. Address correspondence and reprint requests to Dr Nagase: First Department of Oral and Maxillofacial Surgery, School of Dentistry, Niigata University, Gakkocho 2-5274, Niigata City. 951, Japan. 0 1991 American geons
Association
of Oral and Maxillofacial
Sur-
0278-2391/91/4912-0008$3.00/O
1305
BONE SUBSTITUTE
FIGURE 1. Mixture of a-TCP and acid-polysaccharide tion in the process of consolidation.
solu-
The rabbits were killed at 1, 2, 4, 12, and 24 weeks after implantation. Excised specimens were decalcified, stained with hematoxylin-eosin, and examined microscopically. The compression strength of the consolidated TCP implant was about 150 kg/cm2 in 100% humidity. X-ray diffraction of the ol-TCP powder showed the presence of typical TCP peaks, whereas the consolidated TCP implant showed peaks of TCP, calcium hydrophosphate, and calcium glycolate, indicating that a part of the a-TCP had been converted to calcium hydrophosphate and calcium glycolate . Results 1 WEEK In the TCP implant group, the material was present adjacent to the mandibular bone. A mild inflammatory response and muscle damage were observed in the surrounding soft tissues. The implant was surrounded by fibrovascular tissue containing macrophages and a few foreign-body giant cells. A minimum amount of new bone formation was observed in a few places along the elevated periosteum-bone surface (Fig 2). In the TCP-HA implant group, the tissue response was essentially the same as in the TCP group, but the muscle damage was milder and new bone formation was more extensive (Fig 3). In the sham operation group, muscle damage and a little new bone formation were observed along the bone surface. 2 WEEKS In both the TCP implant and TCP-HA implant groups, slight inflammation remained in the operated area. Ingrowth of fivrovascular tissue and re-
FROM o-TCP AND ACID SOLUTION
FIGURE 2. Photomicrograph of TCP implant group at 1 week. The space between implant and bone is occupied by ingrowth of fibrovascular tissue. I, Implant; B, mandibular bone; F, tibrovascular tissue (hematoxylin-eosin stain, original magnification x loo).
generation of muscle tissue were observed in the area of muscle damage. Extensive new bone formation extending from the bone surface was seen along the margins of the implant. Abundant osteoblasts lined the newly formed bone. Some new bone formation was also observed in the space between the implant and the bone, although it was mainly filled with fibrovascular tissue. The newly formed bone was in direct contact with the implant in places. Foreign-body giant cells, macrophages, and occasional calcification were observed in the soft tissue surrounding the implant (Figs 4, 5). In the sham operation group, the ingrowth of fibrovascular tissue containing macrophages and foreign-body giant cells, and newly regenerated muscle tissue in the damaged area, were observed. A little new bone formation was still observed along the bone surface.
FIGURE 3. Photomicrograph of TCP-HA implant group at 1 week. The space between implant and bone is occupied by ingrowth of fibrovascular tissue. New bone formation was observed in places along periosteum-elevated bone surface. B, Mandibular bone; F, fibrovascular tissue. Arrow shows new bone (hematoxylin-eosin stain, original magnification x 100).
1307
NAGASE ET AL
FIGURE 4. Photomicrograph of TCP implant group at 2 weeks. The extensive new bone formation is seen extending from the bone surface to implant. I, Implant; B, mandibular bone; F, tibrovascular tissue. Arrow shows new bone (hemaotxylineosin stain, original magnification X 100).
FIGURE 6. Photomicrograph of TCP implant group at 4 weeks. There is extensive new bone formation extending from the bone surface to the implant. The newly formed bone is in direct contact with the implant. I, Implant; B, mandibular bone. Arrow shows new bone (hematoxylin-eosin stain, original magnification X 100).
4 WEEKS In the TCP implant group, only a minimal inflammatory response was observed in the tissue surrounding the implant. The new bone formation was quite active, particularly along the margins of the implant. The newly formed bone was indirect contact with the implanted material. The pores of the implant were filled with new bone. Osteoclasts were not observed in the space under the implant. The surface of the implant without bone deposition was covered with fibrous tissue containing foreignbody giant cells and macrophages (Fig 6). In the TCP-HA implant group, extensive new bone formation was seen extending from the bone surface into the spaces between the HA particles. The newly formed bone was in direct contact with
FIGURE 5. Photomicrograph of TCP-HA implant group at 2 weeks. The extensive new bone lined by osteoblasts is seen extending from the bone surface to the implant. I, Implant; B, mandibular bone; F, fibrovascular tissue. Arrow shows new bone (hematoxylin-eosin stain, original magnification x 100).
the HA particles in some areas. Abundant foreignbody giant cells and macrophages were observed in the spaces between the HA particles. The softtissue response was essentially the same as in the TCP implant group (Fig 7). In the sham operation group, an inflammatory response was not observed, and there was no longer evidence of new bone formation. 12 WEEKS In the TCP implant group, the lateral and inferior surfaces of the implant were covered with mature lamellar bone in which bone marrow was formed in places. A lining of osteoblasts around the bone was rarely seen. The top of the implant was covered
FIGURE 7. Photomicrograph of TCP-HA implant group at 4 weeks. Note the extensive new bone formation extending from bone surface to the HA. The newly formed bone is in direct contact with the HA. HA, Hydroxylapatite particle; B, mandibular bone. Arrow shows new bone (hematoxylin-eosin stain, original magnification X 100).
1308
BONE SUBSTITUTE
FROM a-TCP AND ACID SOLUTION
with fibrous tissue. There were foreign-body giant cells and macrophages in contact with the implant as well as in the lacunae in some places (Fig 8). In the TCP-HA implant group, the HA particles were partially covered with mature lamellar bone. The tissue response was essentially the same as in the TCP implant group (Fig 9). 24 WEEKS In the TCP implant group, the microscopic findings were similar to those at 12 weeks. The implant showed no evidence of resorption (Fig 10). The tissue response in the three groups is summarized in Table 1. Discussion
The advantage of the materials used in this study is that any desirable contour can be easily achieved during reconstructive bone surgery. The a-TCP powder is hardened in the presence of water because it is converted to octacalcium phosphate or HA by hydration.*“ This reaction is accelerated by heating4,’ or addition of acid.2 In our experience, the (Y-TCP powder did not readily harden at room temperature in the presence of a saline solution.6 The reaction, however, was accelerated by addition of glycolic acid, but the resulting product was quite fragile. Thus, dextran was added to serve as a framework. The consolidated block was firm enough to be used as a bone substitute. A part of the TCP was converted to calcium hydrophosphate and calcium glycolate . Extensive new bone formation extending from the bone surface was seen along the margins of the implant at 2 weeks, and the space between the ma-
FIGURE 8. Photomicrograph of TCP implant group at 12 weeks. The lateral and inferior surfaces of the implant are covered with mature lamellar bone in which bone marrow has formed in places. I, Implant; B, mandibular bone; BM, bone marrow. Arrow shows newly formed bone (hematoxylin-eosin stain, original magnification X 100).
FIGURE 9. Photomicrograph of TCP-HA implant group at 12 weeks. The HA is partially covered with mature lamellar bone. M, TCP material: HA, hydroxylapatite particle; B, mandibular bone. Arrow shows newly formed bone (hematoxylin-eosin stain, original magnification X 100).
terial and bone was completely filled with bone at 4 weeks. The newly formed bone changed into lamellar bone at 12 weeks. Thus, the tissue response to the material was substantially similar to the response to HA particles shown in our previous study. ’ As compared with HA particles, the implant material used here seemed to produce a slightly more pronounced soft-tissue response, possibly due to the presence of the glycolic acid and dextran. The tissue damage from the TCP implant placed within 2 minutes after mixing was slightly more pronounced than that from the TCP-HA implant placed 15 minutes after mixing, possibly because of larger amounts of unreacted glycolic acid and dextran remaining in the TCP implant than in the TCP-HA implant. However, the response disappeared in a short time, probably because the glycolic acid and dextran were metabolized. No adverse effect on bone formation was observed. It is known that tricalcium phosphate is a resorb-
FIGURE 10. Photomicrograph of TCP material at 24 weeks. I, Implant; B, mandibular bone (hematoxylin-eosin stain, original magnification X 100).
1309
NAGASE ET AL
Table 1.
Tissue Responses in the Three Groups TCP Implant Group
TCP-HA Implant Group
Sham Operation Group
Tissue Response
I Wk
2Wk
4Wk
12 Wk
24 Wk
1 Wk
2Wk
4Wk
12 Wk
1 Wk
2Wk
4Wk
Tissue injury Loose tibrovascular tissue New bone formation Macrophages and/or foreignbody giant cells
++ + 2
-c ++ ++
_
_ _
+ + +
? ++ ++
_ + ++
_ 5 -
+ + +
* ++ 2
_
+ ++
_ 2 _
t
+
+
+
+
?
+
+
+
i
&
_
Key: + t , Remarkable;
+ , moderate:
-
2, mild; - , not found
able bone implant.7 In our previous study,6 a-TCP powder implanted in the soft tissue and bone was shown to induce a foreign-body reaction, with the occurrence of abundant multinucleated giant cells adjacent to the wTCP powder. In this study, foreign-body giant cells and macrophages also were observed in the soft tissue in contact with the TCPmaterial, but resorption of the material was not observed in the experimental period. Although the TCP implant might be resorbed after a longer period following implantation, the HA particles added to the TCP implant will remain in the implanted area. Particulate HA is widely used for alveolar ridge augmentation. The difficulty in handling and delivering the material in a proper location and the lack of adhesiveness and plasticity, which may lead to migration of the particles into unintended areas and cause subsequent failure in obtaining a desirable contour, are problems inherent in the particulate form of HA. To overcome these problems, gelatin was used as an adherent in our previous study.s The material reported here was also found to be an excellent material for this purpose.
References 1. Nagase M, Chen RB, Asada Y, et al: Radiographic and microscopic evaluation of subperiosteally implanted blocks of hydrated and hardened a-tricalcium phosphate in rabbits. J Oral Maxillofac Surg 47:582, 1989 2. Monma H, Goto M, Kohmura T: Effect of additive on hydration and hardening of tricalcium phosphate. Gypsum Lime 188:ll. 1984 3. Monma H, Goto M: Succinate-complexed octacalcium phosphate. Bull Chem Sot Jpn 56:3843, 1983 4. Monma H, Ueno S, Kanazawa T: Properties of hydroxyapatite prepared by the hydrolysis of tricalcium phosphate. J Chem Tech Biotechnol 31:15, 1981 5. Monma H, Takahashi T, Ushio H, et al: Preparation and properties of porous apatite by the hydration and hardening method. Gypsum Lime 212:25, 1988 6. Nagase M. Yoshida T, Tamura N, et al: Tissue response against implant of forming from a-tricalcium phosphate. Jpn J Oral Maxillofac Surg 31:3079, 1985 7. Metsger DS, Driskell TD, Paulsrud JR: Tricalcium phosphate ceramic-A resorbable bone implant: review and current status. J Am Dent Assoc 105:1035, 1982 8. Nagase M, Chen RB, Asada Y, et al: Radiographic and microscopic evaluation of subperiosteally implanted block of hydroxylapatite-gelatin mixture in rabbits. J Oral Maxillofac Surg 47:40, 1989
Surg
49.1305-1309.1991
Evaluation of a Bone Substitute Prepared From a-Tricalcium Phosphate and an Acid Polysaccharide Solution MAMORU
NAGASE, DDS, PHD,* RUEY-BIN CHEN, DDS, PiiD,+ YUMl ARAYA, DDS,t AND TAM10 NAKAJIMA, DDS, PHD$
Tissue response to a readily consolidating material prepared by mixing cw-tricalcium phosphate (wTCP) powder with a glycolic acid dextran solution and to this consolidating material combined with particulate hydroxylapatite (HA) was studied after implantation in the subperiosteal space of the mandible in rabbits. Active new bone formation comparable to that seen on HA implants was observed around the two compounds. The newly formed bone was in direct contact with the HA as well as the readily consolidated material and little adverse effect resulting from the glycolic acid and dextran was observed. Because the readily consolidating material was firm and could be countoured into any shape during the process of consolidation, it may be quite useful as a bone substitute and as an adherent for HA particles for reconstructive bone surgery, overcoming the disadvantages inherent to the particulate form of HA.
Materials and Methods
Particulate hydroxylapatite (HA) is widely used for alveolar ridge augmentation of atrophic jaws. The difficulty in delivering the material in a proper location and the lack of adhesiveness and plasticity are problems inherent to the particulate form of HA. A readily consolidating bone substitute would be very useful for alveolar ridge augmentation and reconstructive surgery of bone. In this report, the tissue response to a readily consolidating material prepared by mixing a-TCP and an acid-polysaccharide solution and to this material combined with particulate HA was studied in rabbits.
Glycolic acid was dissolved in distilled water (w/v = 30%), and dextran (molecular weight, 60,000 to 90,000) was added (dextran:solution = 5:4), to produce a viscous acid polysaccharide solution. As shown in Figure 1, the mixture of a-TCP powder with a particle size ranging from 6 to 20 km in diameter (Sankin Kogyo Co Ltd, Tokyo) and the acid polysaccharide solution (powder:solution = 5:7) consolidated in about 2 to 5 minutes to produce a block that was firm, but slightly bendable on thinning (TCP implant). A mixture of wTCP powder and HA particles and the acid-polysaccaharide solution (TCP: HA: solution = 5: 10:7), which became consolidated in about 2 to 5 minutes, was also used to produce a block (TCP-HA implant). The TCP implant was adjusted to the bone surface during the process of consolidation and was implanted within 2 minutes after mixing into the subperiosteal space of the mandible in 14 rabbits as described in a previous article.’ The TCP-HA implant was implanted into eight rabbits 15 minutes after mixing. Four shamoperated rabbits served as the control.
Received from the First Department of Oral and Maxillofacial Surgery, School of Dentistry, Niigata University, Niigata City, Japan. * Fulltime Lecturer. t Resident. $ Professor. Address correspondence and reprint requests to Dr Nagase: First Department of Oral and Maxillofacial Surgery, School of Dentistry, Niigata University, Gakkocho 2-5274, Niigata City. 951, Japan. 0 1991 American geons
Association
of Oral and Maxillofacial
Sur-
0278-2391/91/4912-0008$3.00/O
1305
BONE SUBSTITUTE
FIGURE 1. Mixture of a-TCP and acid-polysaccharide tion in the process of consolidation.
solu-
The rabbits were killed at 1, 2, 4, 12, and 24 weeks after implantation. Excised specimens were decalcified, stained with hematoxylin-eosin, and examined microscopically. The compression strength of the consolidated TCP implant was about 150 kg/cm2 in 100% humidity. X-ray diffraction of the ol-TCP powder showed the presence of typical TCP peaks, whereas the consolidated TCP implant showed peaks of TCP, calcium hydrophosphate, and calcium glycolate, indicating that a part of the a-TCP had been converted to calcium hydrophosphate and calcium glycolate . Results 1 WEEK In the TCP implant group, the material was present adjacent to the mandibular bone. A mild inflammatory response and muscle damage were observed in the surrounding soft tissues. The implant was surrounded by fibrovascular tissue containing macrophages and a few foreign-body giant cells. A minimum amount of new bone formation was observed in a few places along the elevated periosteum-bone surface (Fig 2). In the TCP-HA implant group, the tissue response was essentially the same as in the TCP group, but the muscle damage was milder and new bone formation was more extensive (Fig 3). In the sham operation group, muscle damage and a little new bone formation were observed along the bone surface. 2 WEEKS In both the TCP implant and TCP-HA implant groups, slight inflammation remained in the operated area. Ingrowth of fivrovascular tissue and re-
FROM o-TCP AND ACID SOLUTION
FIGURE 2. Photomicrograph of TCP implant group at 1 week. The space between implant and bone is occupied by ingrowth of fibrovascular tissue. I, Implant; B, mandibular bone; F, tibrovascular tissue (hematoxylin-eosin stain, original magnification x loo).
generation of muscle tissue were observed in the area of muscle damage. Extensive new bone formation extending from the bone surface was seen along the margins of the implant. Abundant osteoblasts lined the newly formed bone. Some new bone formation was also observed in the space between the implant and the bone, although it was mainly filled with fibrovascular tissue. The newly formed bone was in direct contact with the implant in places. Foreign-body giant cells, macrophages, and occasional calcification were observed in the soft tissue surrounding the implant (Figs 4, 5). In the sham operation group, the ingrowth of fibrovascular tissue containing macrophages and foreign-body giant cells, and newly regenerated muscle tissue in the damaged area, were observed. A little new bone formation was still observed along the bone surface.
FIGURE 3. Photomicrograph of TCP-HA implant group at 1 week. The space between implant and bone is occupied by ingrowth of fibrovascular tissue. New bone formation was observed in places along periosteum-elevated bone surface. B, Mandibular bone; F, fibrovascular tissue. Arrow shows new bone (hematoxylin-eosin stain, original magnification x 100).
1307
NAGASE ET AL
FIGURE 4. Photomicrograph of TCP implant group at 2 weeks. The extensive new bone formation is seen extending from the bone surface to implant. I, Implant; B, mandibular bone; F, tibrovascular tissue. Arrow shows new bone (hemaotxylineosin stain, original magnification X 100).
FIGURE 6. Photomicrograph of TCP implant group at 4 weeks. There is extensive new bone formation extending from the bone surface to the implant. The newly formed bone is in direct contact with the implant. I, Implant; B, mandibular bone. Arrow shows new bone (hematoxylin-eosin stain, original magnification X 100).
4 WEEKS In the TCP implant group, only a minimal inflammatory response was observed in the tissue surrounding the implant. The new bone formation was quite active, particularly along the margins of the implant. The newly formed bone was indirect contact with the implanted material. The pores of the implant were filled with new bone. Osteoclasts were not observed in the space under the implant. The surface of the implant without bone deposition was covered with fibrous tissue containing foreignbody giant cells and macrophages (Fig 6). In the TCP-HA implant group, extensive new bone formation was seen extending from the bone surface into the spaces between the HA particles. The newly formed bone was in direct contact with
FIGURE 5. Photomicrograph of TCP-HA implant group at 2 weeks. The extensive new bone lined by osteoblasts is seen extending from the bone surface to the implant. I, Implant; B, mandibular bone; F, fibrovascular tissue. Arrow shows new bone (hematoxylin-eosin stain, original magnification x 100).
the HA particles in some areas. Abundant foreignbody giant cells and macrophages were observed in the spaces between the HA particles. The softtissue response was essentially the same as in the TCP implant group (Fig 7). In the sham operation group, an inflammatory response was not observed, and there was no longer evidence of new bone formation. 12 WEEKS In the TCP implant group, the lateral and inferior surfaces of the implant were covered with mature lamellar bone in which bone marrow was formed in places. A lining of osteoblasts around the bone was rarely seen. The top of the implant was covered
FIGURE 7. Photomicrograph of TCP-HA implant group at 4 weeks. Note the extensive new bone formation extending from bone surface to the HA. The newly formed bone is in direct contact with the HA. HA, Hydroxylapatite particle; B, mandibular bone. Arrow shows new bone (hematoxylin-eosin stain, original magnification X 100).
1308
BONE SUBSTITUTE
FROM a-TCP AND ACID SOLUTION
with fibrous tissue. There were foreign-body giant cells and macrophages in contact with the implant as well as in the lacunae in some places (Fig 8). In the TCP-HA implant group, the HA particles were partially covered with mature lamellar bone. The tissue response was essentially the same as in the TCP implant group (Fig 9). 24 WEEKS In the TCP implant group, the microscopic findings were similar to those at 12 weeks. The implant showed no evidence of resorption (Fig 10). The tissue response in the three groups is summarized in Table 1. Discussion
The advantage of the materials used in this study is that any desirable contour can be easily achieved during reconstructive bone surgery. The a-TCP powder is hardened in the presence of water because it is converted to octacalcium phosphate or HA by hydration.*“ This reaction is accelerated by heating4,’ or addition of acid.2 In our experience, the (Y-TCP powder did not readily harden at room temperature in the presence of a saline solution.6 The reaction, however, was accelerated by addition of glycolic acid, but the resulting product was quite fragile. Thus, dextran was added to serve as a framework. The consolidated block was firm enough to be used as a bone substitute. A part of the TCP was converted to calcium hydrophosphate and calcium glycolate . Extensive new bone formation extending from the bone surface was seen along the margins of the implant at 2 weeks, and the space between the ma-
FIGURE 8. Photomicrograph of TCP implant group at 12 weeks. The lateral and inferior surfaces of the implant are covered with mature lamellar bone in which bone marrow has formed in places. I, Implant; B, mandibular bone; BM, bone marrow. Arrow shows newly formed bone (hematoxylin-eosin stain, original magnification X 100).
FIGURE 9. Photomicrograph of TCP-HA implant group at 12 weeks. The HA is partially covered with mature lamellar bone. M, TCP material: HA, hydroxylapatite particle; B, mandibular bone. Arrow shows newly formed bone (hematoxylin-eosin stain, original magnification X 100).
terial and bone was completely filled with bone at 4 weeks. The newly formed bone changed into lamellar bone at 12 weeks. Thus, the tissue response to the material was substantially similar to the response to HA particles shown in our previous study. ’ As compared with HA particles, the implant material used here seemed to produce a slightly more pronounced soft-tissue response, possibly due to the presence of the glycolic acid and dextran. The tissue damage from the TCP implant placed within 2 minutes after mixing was slightly more pronounced than that from the TCP-HA implant placed 15 minutes after mixing, possibly because of larger amounts of unreacted glycolic acid and dextran remaining in the TCP implant than in the TCP-HA implant. However, the response disappeared in a short time, probably because the glycolic acid and dextran were metabolized. No adverse effect on bone formation was observed. It is known that tricalcium phosphate is a resorb-
FIGURE 10. Photomicrograph of TCP material at 24 weeks. I, Implant; B, mandibular bone (hematoxylin-eosin stain, original magnification X 100).
1309
NAGASE ET AL
Table 1.
Tissue Responses in the Three Groups TCP Implant Group
TCP-HA Implant Group
Sham Operation Group
Tissue Response
I Wk
2Wk
4Wk
12 Wk
24 Wk
1 Wk
2Wk
4Wk
12 Wk
1 Wk
2Wk
4Wk
Tissue injury Loose tibrovascular tissue New bone formation Macrophages and/or foreignbody giant cells
++ + 2
-c ++ ++
_
_ _
+ + +
? ++ ++
_ + ++
_ 5 -
+ + +
* ++ 2
_
+ ++
_ 2 _
t
+
+
+
+
?
+
+
+
i
&
_
Key: + t , Remarkable;
+ , moderate:
-
2, mild; - , not found
able bone implant.7 In our previous study,6 a-TCP powder implanted in the soft tissue and bone was shown to induce a foreign-body reaction, with the occurrence of abundant multinucleated giant cells adjacent to the wTCP powder. In this study, foreign-body giant cells and macrophages also were observed in the soft tissue in contact with the TCPmaterial, but resorption of the material was not observed in the experimental period. Although the TCP implant might be resorbed after a longer period following implantation, the HA particles added to the TCP implant will remain in the implanted area. Particulate HA is widely used for alveolar ridge augmentation. The difficulty in handling and delivering the material in a proper location and the lack of adhesiveness and plasticity, which may lead to migration of the particles into unintended areas and cause subsequent failure in obtaining a desirable contour, are problems inherent in the particulate form of HA. To overcome these problems, gelatin was used as an adherent in our previous study.s The material reported here was also found to be an excellent material for this purpose.
References 1. Nagase M, Chen RB, Asada Y, et al: Radiographic and microscopic evaluation of subperiosteally implanted blocks of hydrated and hardened a-tricalcium phosphate in rabbits. J Oral Maxillofac Surg 47:582, 1989 2. Monma H, Goto M, Kohmura T: Effect of additive on hydration and hardening of tricalcium phosphate. Gypsum Lime 188:ll. 1984 3. Monma H, Goto M: Succinate-complexed octacalcium phosphate. Bull Chem Sot Jpn 56:3843, 1983 4. Monma H, Ueno S, Kanazawa T: Properties of hydroxyapatite prepared by the hydrolysis of tricalcium phosphate. J Chem Tech Biotechnol 31:15, 1981 5. Monma H, Takahashi T, Ushio H, et al: Preparation and properties of porous apatite by the hydration and hardening method. Gypsum Lime 212:25, 1988 6. Nagase M. Yoshida T, Tamura N, et al: Tissue response against implant of forming from a-tricalcium phosphate. Jpn J Oral Maxillofac Surg 31:3079, 1985 7. Metsger DS, Driskell TD, Paulsrud JR: Tricalcium phosphate ceramic-A resorbable bone implant: review and current status. J Am Dent Assoc 105:1035, 1982 8. Nagase M, Chen RB, Asada Y, et al: Radiographic and microscopic evaluation of subperiosteally implanted block of hydroxylapatite-gelatin mixture in rabbits. J Oral Maxillofac Surg 47:40, 1989
