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Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation
Trauma; preprosthetic surgery
Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation
G(inter Hotz Department of Maxillofacial Surgery, University of Heidelberg, Germany
Part I: An experimental study G. Hotz: Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation. Part L" An experimental study. Int. J. Oral Maxillofac. Surg. 1991; 20." 204-207. Abstract. Histological studies in animals have shown that fibrin sealant can be employed as a resorbable, biological binding agent for fixation o f initially mouldable hydroxylapatite (HA) implants. Mixing H A granules with a 2 component fibrin sealant from which thrombin solution has been diluted to 1 I U / m l provides a simple m e t h o d for obtaining mouldable implants. During insertion of the H A granules, the sealant prevents dislocation and migration, and on solidification, the moulded implant securely retains its shape and position until connective tissue ingrowth is complete. The use of polygonal granules permits a constant implant contour from the very beginning.
A major problem in the reconstruction of the atrophic alveolar ridge with H A granules is the potential dislocation and migration of the granules. The adhesive effect of a resorbable organic sealant system for the fixation of H A granules was therefore investigated. The fibrin sealant system mimicks the last phase of blood clotting by converting fibrinogen to fibrin with the aid of thrombin. Fibrin sealing is currently successfully used in surgery for reuniting tissues, sealing wounds, accomplishing local haemostasis and promoting wound healing 6.
Material and methods The HA-fibrin sealant mixture was prepared by mixing the granules (Interpore TM 200, Interpore Int., Irvine CA, USA) with a 2-component fibrin sealant system (Tissucol®, or Tisseel ®*, Immuno GmbH, Heidelberg, Germany). The first component (sealer), which is prefilled in a syringe and deep-frozen, consists mainly of human plasma protein concentrate (80-120 mg/ml), fibrinogen (70-110
* Tissucol and Tisseet are registered trademarks of IMMUNO's 2-component fibrin sealant in different countries.
mg/ml), fibronectin (2-9 mg/ml), factor XIII (10-50 U) and plasminogen (0.02-0.08 rag/ ml). Thrombin, calcium chloride and an antifibrinolytic make up the second component. This activator stabilizer can be modified using an application kit (Fig. 1) which contains the following solutions: A. Fibrinolysis inhibitor (aprotinin), 3000 KIU/ml B. Calcium chloride, 40 mM C. Thrombin L, bovine, lyophylised, 4 IU/ ml D. Thrombin S, bovine, lyophylised, 500 IU/ ml. The thrombin solution was diluted from 4 IU/ml down to 1 IU/ml. This was accomplished with the application kit by dissolving thrombin L (C) in 1 ml of the calcium chloride solution (B) and then mixing this with 3 ml of the aprotinin-calcium chloride solution. The aprotinin concentration is thereby lowered from 3000 to 2250 KIU/ml. The thawed and warmed sealer and the modified thrombin solution were simultaneously applied using the Duplojet device. A commercially available glass syringe was loaded to one third with the modified, thin 2-component fibrin sealant and filled up with HA granules. The contents were then immediately mixed to yield a paste. Six grams HA required approximately 1 ml of the sealant for binding, with optimum fluidity being reached at 37°C. Delivery of the HA-fribrin sealant mixture from the syringe was possible for at least 10 min before clotting, and the material could easily be moulded in situ for
Key words: alveolar ridge augmentation; contour augmentation; hydroxylapatite; fibrin sealant; implants Accepted for publication 13 February 1991
another 10 min prior to soldification. The resulting HA-fibrin implant, based on a sealer protein concentration of 80 120 mg/ ml, contains up to 2% (v/v) protein and 63% (v/v) HA. The remainder consists of water and salts from the sealant. Experiments conducted in 12 adult male Wistar rats were designed to test the suitability of the biological binding agent, fibrin, as a temporary stabilizer of HA granules. The items studied included: the host-tissue response and whether resorption of the binder led to condensation of the granules. 200-mg samples of fibrin-bound HA were therefore implanted into paravertebral muscle pouches. In addition, rounded nonporous HA (Calcitite® 2040, Calcitek Inc., Carlsbad CA, USA) and polygonal macroporous HA (Interpore 200 TM) were implanted without-fibrin adhesive. The specimens were retrieved after 1, 2, 3 and 4 weeks, and fixed in 70% alcohol. Per period investigated (3 animals), 10 sections were examined histologically. By combining the epoxy resin plastination - a method of tissue preservation with epoxy resinz,3 - with the sawing and grinding technique ~ undecalcified sections were produced and evaluated by light microscopy. The average distance between granules (interparticulate distance) was determined and used as a parameter for measuring implant condensation. Quantitative evaluation was carried out using a Zeiss ocular with 100 measuring points and 10 measuring lines. Quantitative assessment of tissue ingrowth was accomplished by computerized histo-
HA-fibrin implants for ridge augmentation I
205
morphometry (MOP Videoplan System®, Kontron Electronics, Germany).
Results
Fig. 1. Tissucol® fibrin sealant kit comprising a fibrinolysis inhibitor (A), calcium chloride solution (B), thrombin 4 IU (C), and thrombin 500 IU (D). The Duplojet syringe is shown after assembly.
By combining the methods of epoxy resin plastination2 with the sawing and grinding technique of DONATH& BREUYE~1, undecalcified 10 /tm sections of HA granules with adjacent soft and hard tissue can be produced and evaluated by light microscopy using transmitted or incident illumination. The clear, thin sections contain a minimum of artifacts, e.g. bending, cracks, fissures, scratchers or bubbles, especially along the tissue-implant interface. The hard and soft tissue is preserved adjacent to the granular implant3. In the in vitro preparation of fibrinbound HA, the HA granules were interconnected by a network of fibrin links (Fig. 2). Centripetal resorption of the
Fig. 2. a) In vitro preparation of hydroxylapatite (HA) granules fixed with fibrin links (10-#m sawing-grinding section, phloxin staining, 16 x ) b) Detail of fibrin link between granules (toluidine blue, 40 x ).
Fig. 3. After 8 days in the rat muscle pouch, the fibrin links have been sequentially resorbed, and newly formed granulation tissue has filled the spaces between granules (toluidine blue, 40 x ).
Fig.4. After 4 weeks, complete resorption of the fibrin links has taken place. The connective tissue between granules is rich in blood vessels and fibroblasts (toluidine blue, 40 x ).
Hotz
206 %
Histomorphometry
60-.
[Mean-(%) + Standard Dev.] 53,3g
52.72 i0.34
~10.41
53.24 1"0,15
50-
53,23 ~0,13
:It
.
:k1,22 38.13 *+.12
~.1o
40-
_1;71Hydroxylapotite
*o.91
Connective
Tissue
30-
Fibrin 20-
Spaces 7.15 io.96 1.911 .21
10,
0
s
2.43 0.63 Ill.go ~ ) . 5 7 ,47~ ,~ 0 , 8 0
,
18
24
t.03 ~.~ ,
32
Days
Fig. 5. Histomorphometrical analysis shows that the fibrin links have almost completely been
resorbed after 2 weeks. 4 weeks after implantation, the spaces between granules have been replaced by fibroblast-rich connective tissue.
observed with polygonal granules (Interpore) was 9% and thus less pronounced than the 18% found with the rounded ceramic (Calcitite). In the case of polygonal fibrin-bound granules, the mean distance between particles was only marginally reduced by 3% during connective tissue ingrowth (Fig. 6).
fibrin septa was accompanied by pronounced connected tissue proliferation (Fig. 3). Histomorphometry of the fibrin-free H A implants showed complete connective tissue ingrowth into the spaces between the particles after 8 days. Two weeks after implantation, the sealant in the fibrin-bound implants had almost entirely been resorbed (Fig. 4). The spaces between the H A particles were gradually filled with granulation tissue. Inflammation was minimal and there were no foreign-body reactions. At 4 weeks the tissue had differentiated into fibroblast-rich connective tissue (Fig. 5). During the process of fibrovascular tissue infiltration, condensation
Discussion
Fibrin sealing mimicks the last phase of blood clotting where thrombin converts fibrinogen to monomeric fibrin. This then forms aggregated, cross-linked fibrin. In the presence of calcium, thrombin simultaneously activates factor
Interparticulate Distance [Mean 18o
(gm)
*/-
Standard
Deviation]
(IJm) 102.08 */-1,78
160 ~0.58 */-1.19
~
~ ~ * / - 2 , O S
2
.
~
/
-
0
.
141.00 - / - 2 . 0 0
0
0
147.59 +/-0.00
141.62";/-0.10
180.80 -~-0.40
140 122.00 ~/-2.84
128.10 +/-2,04
0
120
*1-1.68
100 80 in Vitro
8 ~
Intorpore
100.00 *1-2,21
1
i
J
16
24
32 DAY8
~ Interpore
*
Fibrin
o Caloitite
Fig. 6. Distance between particles [mean (~m) _+SD]. HA-implant condensation during connec-
tive tissue ingrowth was 18%, 9% and 3% for the rounded ceramic (Calcitite®), the polygonal ceramic (InterporeTM) and the Interpore-fibrin combination.
XIII, which in turn converts soluble fibrin into polymeric urea-insoluble fibrin. The 2-component tissue adhesive kit, Tissucol, comes with a prefilled syringe containing a human plasma protein preparation and an application set for producing thromI~in solutions with thrombin concentrations of 4 IU/ml (thrombin L) or 500 IU/ml (thrombin S). The rate of solidification depends on the thrombin concentration used. The onset of solidification is several seconds with thrombin S and 60 s with thrombin L 1]. At the higher dilution we chose, solidificati~on of the sealer proteins began after approx, l0 min and was complete after approx. 20 rain. The delay in solidification allowed sufficient time to deliver the HA-fibrin paste with a syringe and shape the implant. The rate of resorption of fibrin sealant is dependent on the amount of sealant and the place and species in which it is used. PEscn & SCI-I~EL~8 investigated the resorption of fibrin sealant in canine muscles and found a fibrin clot to be infiltrated by neutrophil granulocytes and macrophages after 3 days; its replacement by fibroblast-rich connective tissue was largely complete after 8 days. In the well-vascularized tissue of the spleen, where there is increased fibrinolytic activity, the sealant is more rapidly degraded than in the bradytrophic tissue of the middle ear 5,1°. R~cK & BERNAL-SPREKELSEN9 filled trepanation defects in rabbits with TCP-fibrin sealant and with HA-fibrin sealant. The related homologous fibrin sealant promotes connective tissue proliferation and by doing so retards osseous integration of the ceramic. According to O S B O R N ' S 7 investigations, fibrin sealant retards osseous integration of H A granules in trepanation defects in the femoral bone of the dog. Subperiosteal implantation of ceramic material in the rat is only possible on the' calvaria.Apart from the restricted space, a lack of mechanical strain on the implant makes this model inappropriate for assessing resorption and preservation of shape. The friction that the implanted granules are exposed to in the muscle pouch more likely corresponds to the forces acting on the implant in the prosthetically rehabilitated augmented alveolar ridge. These considerations led us to choose intramuscular in preference to subcutaneous implantation. H A implants deposited without fibrin sealant in rat muscle pouches showed
HA-fibrin implants for ridge augmentation I complete connective tissue ingrowth after 8 days 4. According to our observations, the presence of fibrin links between H A granules delayed fibrous integration of the ceramic by 8 days, and only after 2 weeks was resorption of the fibrin links in the centre of the implants practically complete. Sequential resorption of fibrin links was accompanied by pronounced connective tissue proliferation. Of particular interest was the question as to whether resorption of fibrin binder led to condensation of the ceramic implants. According to our findings, fibrovascnlar infiltration of implants made up of polygonal, microporous, coralline granules underwent 9% condensation. In comparison, the mean distance between rounded granules decreased by 18%. The combination of polygonal granules and fibrin sealant reduced condensation to only 3%, i.e. the change in implant volume was negligible. This study showed that, when using a modified thrombin activator/stabilizer, it is possible to obtain a fibrin sealant with delayed solidification. This sealant can then be used as a binder by
mixing it with polygonal H A granules to yield a paste which makes the H A implant mouldable in its initial phase. Gradual replacement of fibrin links by connective tissue is accompanied by marginal condensation of the H A granules.
References
1. DONATH K, BREUNERG. A method for the study of undecaleified bones and teeth with attached soft tissue. J Oral Pathol 1982: 11: 318-26. 2. HAGENSG V, TIEDEMANNK, KRIZ W. The current potential of plastination. Anat Embryol 1987: 175: 411-21. 3. HOTZ G, GILDEH, M*NNL R, H6NER T. Plastination of granular hydroxylapatite and attached tissue. J Int Soc Plastination 1991: 5: (in press). 4. HOTZ G, MALL G, BORN IA, GILDE H. Koltagen undFibrin ats biologische Bindemittel ffir Hydroxylapatit-Granulat. Dtsch Z Mund Kiefer Gesichts Chir 1989: 13: 296-300. 5. KRAM HB, HINO ST, HARLEYDR FLEMING AW, SHOEMAKERWC. Use of concentrated fibrinogen in experimental splenic
trauma, J Biomed Mater Res 1986: 20: 547-53.
207
6. MATRASH. Fibrin seal: The state of the art. J Oral Maxillofac Surg 1985: 43: 605-I 1. 7. OSBORN JF. Die enossale Implantation von Hydroxylapatit.Keramik unter Verwendung des Fibrinklebesystems. Dtsch ZahnS.rztl Z 1983: 38: 956-8. 8. PESCttH J, SCHEELEJ. Lokaler Fibrinkleberabbau im Tierexperiment Histomorphotogische Untersuehungen. In: SCHEELE J, ed. Fibrinklebung. Berlin: Springer, 1984: 38~44. 9. RECK R, BERNAL-SPREKELSENM. Fibrinkleber und Tricalciumphosphat-Implantate in der Mittelohrchirurgie. Eine tierexperimentelle Studie. Laryngo-Rhino-Otol 1989: 68: 15~6. 10. R/3HL H. Beitrag zur Erprobung des Fibrinklebers: Anwendung im Tierexperiment bei Mittelohroperationen. Doctoral thesis, Erlangen 1981. 11. SEELICHT, REDL H. Theoretische Grundlgen des Fibrinklebers. In: SCmMPF K, ed. Fibrinogen und Fibrinkleber. Stuttgart: FK Schattauer, 1980: 199508. Address: Priv.-Daz. Dr. Dr. med. Gf~nterHotz Department of Maxillofaeial Surgery University of Heidelberg Im Neuenheimer Feld 400 D-6900 Heidelberg Germany
Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation
G(inter Hotz Department of Maxillofacial Surgery, University of Heidelberg, Germany
Part I: An experimental study G. Hotz: Alveolar ridge augmentation with hydroxylapatite using fibrin sealant for fixation. Part L" An experimental study. Int. J. Oral Maxillofac. Surg. 1991; 20." 204-207. Abstract. Histological studies in animals have shown that fibrin sealant can be employed as a resorbable, biological binding agent for fixation o f initially mouldable hydroxylapatite (HA) implants. Mixing H A granules with a 2 component fibrin sealant from which thrombin solution has been diluted to 1 I U / m l provides a simple m e t h o d for obtaining mouldable implants. During insertion of the H A granules, the sealant prevents dislocation and migration, and on solidification, the moulded implant securely retains its shape and position until connective tissue ingrowth is complete. The use of polygonal granules permits a constant implant contour from the very beginning.
A major problem in the reconstruction of the atrophic alveolar ridge with H A granules is the potential dislocation and migration of the granules. The adhesive effect of a resorbable organic sealant system for the fixation of H A granules was therefore investigated. The fibrin sealant system mimicks the last phase of blood clotting by converting fibrinogen to fibrin with the aid of thrombin. Fibrin sealing is currently successfully used in surgery for reuniting tissues, sealing wounds, accomplishing local haemostasis and promoting wound healing 6.
Material and methods The HA-fibrin sealant mixture was prepared by mixing the granules (Interpore TM 200, Interpore Int., Irvine CA, USA) with a 2-component fibrin sealant system (Tissucol®, or Tisseel ®*, Immuno GmbH, Heidelberg, Germany). The first component (sealer), which is prefilled in a syringe and deep-frozen, consists mainly of human plasma protein concentrate (80-120 mg/ml), fibrinogen (70-110
* Tissucol and Tisseet are registered trademarks of IMMUNO's 2-component fibrin sealant in different countries.
mg/ml), fibronectin (2-9 mg/ml), factor XIII (10-50 U) and plasminogen (0.02-0.08 rag/ ml). Thrombin, calcium chloride and an antifibrinolytic make up the second component. This activator stabilizer can be modified using an application kit (Fig. 1) which contains the following solutions: A. Fibrinolysis inhibitor (aprotinin), 3000 KIU/ml B. Calcium chloride, 40 mM C. Thrombin L, bovine, lyophylised, 4 IU/ ml D. Thrombin S, bovine, lyophylised, 500 IU/ ml. The thrombin solution was diluted from 4 IU/ml down to 1 IU/ml. This was accomplished with the application kit by dissolving thrombin L (C) in 1 ml of the calcium chloride solution (B) and then mixing this with 3 ml of the aprotinin-calcium chloride solution. The aprotinin concentration is thereby lowered from 3000 to 2250 KIU/ml. The thawed and warmed sealer and the modified thrombin solution were simultaneously applied using the Duplojet device. A commercially available glass syringe was loaded to one third with the modified, thin 2-component fibrin sealant and filled up with HA granules. The contents were then immediately mixed to yield a paste. Six grams HA required approximately 1 ml of the sealant for binding, with optimum fluidity being reached at 37°C. Delivery of the HA-fribrin sealant mixture from the syringe was possible for at least 10 min before clotting, and the material could easily be moulded in situ for
Key words: alveolar ridge augmentation; contour augmentation; hydroxylapatite; fibrin sealant; implants Accepted for publication 13 February 1991
another 10 min prior to soldification. The resulting HA-fibrin implant, based on a sealer protein concentration of 80 120 mg/ ml, contains up to 2% (v/v) protein and 63% (v/v) HA. The remainder consists of water and salts from the sealant. Experiments conducted in 12 adult male Wistar rats were designed to test the suitability of the biological binding agent, fibrin, as a temporary stabilizer of HA granules. The items studied included: the host-tissue response and whether resorption of the binder led to condensation of the granules. 200-mg samples of fibrin-bound HA were therefore implanted into paravertebral muscle pouches. In addition, rounded nonporous HA (Calcitite® 2040, Calcitek Inc., Carlsbad CA, USA) and polygonal macroporous HA (Interpore 200 TM) were implanted without-fibrin adhesive. The specimens were retrieved after 1, 2, 3 and 4 weeks, and fixed in 70% alcohol. Per period investigated (3 animals), 10 sections were examined histologically. By combining the epoxy resin plastination - a method of tissue preservation with epoxy resinz,3 - with the sawing and grinding technique ~ undecalcified sections were produced and evaluated by light microscopy. The average distance between granules (interparticulate distance) was determined and used as a parameter for measuring implant condensation. Quantitative evaluation was carried out using a Zeiss ocular with 100 measuring points and 10 measuring lines. Quantitative assessment of tissue ingrowth was accomplished by computerized histo-
HA-fibrin implants for ridge augmentation I
205
morphometry (MOP Videoplan System®, Kontron Electronics, Germany).
Results
Fig. 1. Tissucol® fibrin sealant kit comprising a fibrinolysis inhibitor (A), calcium chloride solution (B), thrombin 4 IU (C), and thrombin 500 IU (D). The Duplojet syringe is shown after assembly.
By combining the methods of epoxy resin plastination2 with the sawing and grinding technique of DONATH& BREUYE~1, undecalcified 10 /tm sections of HA granules with adjacent soft and hard tissue can be produced and evaluated by light microscopy using transmitted or incident illumination. The clear, thin sections contain a minimum of artifacts, e.g. bending, cracks, fissures, scratchers or bubbles, especially along the tissue-implant interface. The hard and soft tissue is preserved adjacent to the granular implant3. In the in vitro preparation of fibrinbound HA, the HA granules were interconnected by a network of fibrin links (Fig. 2). Centripetal resorption of the
Fig. 2. a) In vitro preparation of hydroxylapatite (HA) granules fixed with fibrin links (10-#m sawing-grinding section, phloxin staining, 16 x ) b) Detail of fibrin link between granules (toluidine blue, 40 x ).
Fig. 3. After 8 days in the rat muscle pouch, the fibrin links have been sequentially resorbed, and newly formed granulation tissue has filled the spaces between granules (toluidine blue, 40 x ).
Fig.4. After 4 weeks, complete resorption of the fibrin links has taken place. The connective tissue between granules is rich in blood vessels and fibroblasts (toluidine blue, 40 x ).
Hotz
206 %
Histomorphometry
60-.
[Mean-(%) + Standard Dev.] 53,3g
52.72 i0.34
~10.41
53.24 1"0,15
50-
53,23 ~0,13
:It
.
:k1,22 38.13 *+.12
~.1o
40-
_1;71Hydroxylapotite
*o.91
Connective
Tissue
30-
Fibrin 20-
Spaces 7.15 io.96 1.911 .21
10,
0
s
2.43 0.63 Ill.go ~ ) . 5 7 ,47~ ,~ 0 , 8 0
,
18
24
t.03 ~.~ ,
32
Days
Fig. 5. Histomorphometrical analysis shows that the fibrin links have almost completely been
resorbed after 2 weeks. 4 weeks after implantation, the spaces between granules have been replaced by fibroblast-rich connective tissue.
observed with polygonal granules (Interpore) was 9% and thus less pronounced than the 18% found with the rounded ceramic (Calcitite). In the case of polygonal fibrin-bound granules, the mean distance between particles was only marginally reduced by 3% during connective tissue ingrowth (Fig. 6).
fibrin septa was accompanied by pronounced connected tissue proliferation (Fig. 3). Histomorphometry of the fibrin-free H A implants showed complete connective tissue ingrowth into the spaces between the particles after 8 days. Two weeks after implantation, the sealant in the fibrin-bound implants had almost entirely been resorbed (Fig. 4). The spaces between the H A particles were gradually filled with granulation tissue. Inflammation was minimal and there were no foreign-body reactions. At 4 weeks the tissue had differentiated into fibroblast-rich connective tissue (Fig. 5). During the process of fibrovascular tissue infiltration, condensation
Discussion
Fibrin sealing mimicks the last phase of blood clotting where thrombin converts fibrinogen to monomeric fibrin. This then forms aggregated, cross-linked fibrin. In the presence of calcium, thrombin simultaneously activates factor
Interparticulate Distance [Mean 18o
(gm)
*/-
Standard
Deviation]
(IJm) 102.08 */-1,78
160 ~0.58 */-1.19
~
~ ~ * / - 2 , O S
2
.
~
/
-
0
.
141.00 - / - 2 . 0 0
0
0
147.59 +/-0.00
141.62";/-0.10
180.80 -~-0.40
140 122.00 ~/-2.84
128.10 +/-2,04
0
120
*1-1.68
100 80 in Vitro
8 ~
Intorpore
100.00 *1-2,21
1
i
J
16
24
32 DAY8
~ Interpore
*
Fibrin
o Caloitite
Fig. 6. Distance between particles [mean (~m) _+SD]. HA-implant condensation during connec-
tive tissue ingrowth was 18%, 9% and 3% for the rounded ceramic (Calcitite®), the polygonal ceramic (InterporeTM) and the Interpore-fibrin combination.
XIII, which in turn converts soluble fibrin into polymeric urea-insoluble fibrin. The 2-component tissue adhesive kit, Tissucol, comes with a prefilled syringe containing a human plasma protein preparation and an application set for producing thromI~in solutions with thrombin concentrations of 4 IU/ml (thrombin L) or 500 IU/ml (thrombin S). The rate of solidification depends on the thrombin concentration used. The onset of solidification is several seconds with thrombin S and 60 s with thrombin L 1]. At the higher dilution we chose, solidificati~on of the sealer proteins began after approx, l0 min and was complete after approx. 20 rain. The delay in solidification allowed sufficient time to deliver the HA-fibrin paste with a syringe and shape the implant. The rate of resorption of fibrin sealant is dependent on the amount of sealant and the place and species in which it is used. PEscn & SCI-I~EL~8 investigated the resorption of fibrin sealant in canine muscles and found a fibrin clot to be infiltrated by neutrophil granulocytes and macrophages after 3 days; its replacement by fibroblast-rich connective tissue was largely complete after 8 days. In the well-vascularized tissue of the spleen, where there is increased fibrinolytic activity, the sealant is more rapidly degraded than in the bradytrophic tissue of the middle ear 5,1°. R~cK & BERNAL-SPREKELSEN9 filled trepanation defects in rabbits with TCP-fibrin sealant and with HA-fibrin sealant. The related homologous fibrin sealant promotes connective tissue proliferation and by doing so retards osseous integration of the ceramic. According to O S B O R N ' S 7 investigations, fibrin sealant retards osseous integration of H A granules in trepanation defects in the femoral bone of the dog. Subperiosteal implantation of ceramic material in the rat is only possible on the' calvaria.Apart from the restricted space, a lack of mechanical strain on the implant makes this model inappropriate for assessing resorption and preservation of shape. The friction that the implanted granules are exposed to in the muscle pouch more likely corresponds to the forces acting on the implant in the prosthetically rehabilitated augmented alveolar ridge. These considerations led us to choose intramuscular in preference to subcutaneous implantation. H A implants deposited without fibrin sealant in rat muscle pouches showed
HA-fibrin implants for ridge augmentation I complete connective tissue ingrowth after 8 days 4. According to our observations, the presence of fibrin links between H A granules delayed fibrous integration of the ceramic by 8 days, and only after 2 weeks was resorption of the fibrin links in the centre of the implants practically complete. Sequential resorption of fibrin links was accompanied by pronounced connective tissue proliferation. Of particular interest was the question as to whether resorption of fibrin binder led to condensation of the ceramic implants. According to our findings, fibrovascnlar infiltration of implants made up of polygonal, microporous, coralline granules underwent 9% condensation. In comparison, the mean distance between rounded granules decreased by 18%. The combination of polygonal granules and fibrin sealant reduced condensation to only 3%, i.e. the change in implant volume was negligible. This study showed that, when using a modified thrombin activator/stabilizer, it is possible to obtain a fibrin sealant with delayed solidification. This sealant can then be used as a binder by
mixing it with polygonal H A granules to yield a paste which makes the H A implant mouldable in its initial phase. Gradual replacement of fibrin links by connective tissue is accompanied by marginal condensation of the H A granules.
References
1. DONATH K, BREUNERG. A method for the study of undecaleified bones and teeth with attached soft tissue. J Oral Pathol 1982: 11: 318-26. 2. HAGENSG V, TIEDEMANNK, KRIZ W. The current potential of plastination. Anat Embryol 1987: 175: 411-21. 3. HOTZ G, GILDEH, M*NNL R, H6NER T. Plastination of granular hydroxylapatite and attached tissue. J Int Soc Plastination 1991: 5: (in press). 4. HOTZ G, MALL G, BORN IA, GILDE H. Koltagen undFibrin ats biologische Bindemittel ffir Hydroxylapatit-Granulat. Dtsch Z Mund Kiefer Gesichts Chir 1989: 13: 296-300. 5. KRAM HB, HINO ST, HARLEYDR FLEMING AW, SHOEMAKERWC. Use of concentrated fibrinogen in experimental splenic
trauma, J Biomed Mater Res 1986: 20: 547-53.
207
6. MATRASH. Fibrin seal: The state of the art. J Oral Maxillofac Surg 1985: 43: 605-I 1. 7. OSBORN JF. Die enossale Implantation von Hydroxylapatit.Keramik unter Verwendung des Fibrinklebesystems. Dtsch ZahnS.rztl Z 1983: 38: 956-8. 8. PESCttH J, SCHEELEJ. Lokaler Fibrinkleberabbau im Tierexperiment Histomorphotogische Untersuehungen. In: SCHEELE J, ed. Fibrinklebung. Berlin: Springer, 1984: 38~44. 9. RECK R, BERNAL-SPREKELSENM. Fibrinkleber und Tricalciumphosphat-Implantate in der Mittelohrchirurgie. Eine tierexperimentelle Studie. Laryngo-Rhino-Otol 1989: 68: 15~6. 10. R/3HL H. Beitrag zur Erprobung des Fibrinklebers: Anwendung im Tierexperiment bei Mittelohroperationen. Doctoral thesis, Erlangen 1981. 11. SEELICHT, REDL H. Theoretische Grundlgen des Fibrinklebers. In: SCmMPF K, ed. Fibrinogen und Fibrinkleber. Stuttgart: FK Schattauer, 1980: 199508. Address: Priv.-Daz. Dr. Dr. med. Gf~nterHotz Department of Maxillofaeial Surgery University of Heidelberg Im Neuenheimer Feld 400 D-6900 Heidelberg Germany