Wound healing of endosteal vitreous carbon inplants in dogs Abdulmola H. Al-Salman, B.D.S., M.S.,* Fayez S. Sayegh, D.M.D., Ph.D.,** and Robert P. Chappell, D.D.S.*** Cniversity of Missouri. School of Dentistry, Kansas City, Mo.
T
he use of dental implants has been thoroughly described in the dental and medical literature since 1891. Throughout this period there has been a desire to replace missing natural teeth with prostheses that could be implanted within the jaws. The development and application of safe and effective dental implants as replacements for natural teeth has long been the main goal of implant dentistry. Yet as great as the need appears to be, safer and more effective human implants are still desired. Dental researchers currently use various classes of materials in their search for a substance which will fulfill the criteria for implants in the oral environment. Among the materials considered are metals,‘.” plastics,‘!,-” and ceramics.” Of these materials, metals have been the most widely used and the most successful to date. Metals are used as both endosteal and subperiosteal implants. One trend of dental implants currently involves the use of a nonmetallic material, the endosteal vitreous carbon implant. Vitreous carbon is a glassy form of pure carbon which is fabricated by thermally degrading a resin under inert atmosphere and then under vacuum, leaving 99.98% pure carbon.” The endosteal vitreous carbon implant can be placed in either fresh tooth extraction sites or in sockets prepared in edentulous ridges.” Voss and Grenoble”’ reported in a 48-month study in humans! an excellent gingival tissue response to This research was supported by the Ministry of Higher Education, Baghdad, Iraq. Condensed from an AMM.S. Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Oral Biology at the University of Missouri, School of Dentistry. *Assistant Professor, Department of Removable Prosthodontics. **Professor and Chairman, Department of Histology. ***Associate Professor and Chairman. Department of Dental Materials.
002%3913/79/010083
+ 07$00.70/O c 1979 The C. V. Mosby Co.
vitreous carbon. They also stated that plaque accumulation on the implants was readily washed away with water and that calculus formation was not evident on the implant surfaces. In addition. the authors reported an apparent remodeling of bone around vitreous carbon implants as determined by histologic and radiographic examination. In contrast to these results, Maropis and associates” reported from their comparative study of vitreous carbon implants in rabbit mandibles that none of their implants were completely biocompatible with rabbit mandibular tissues. Although a different species of experimental animal was employed, they concluded that histologic evidence did not agree with that reported in dogs by Grenoble and Kim.“ Benson,“’ Mooney and Hartmann,“’ and Kadefors and associates’” studied the histologic reactions of vitreous carbon implants and concluded that further investigations were needed to determine the feasibility of using vitreous carbon as a dental implant. The present study was undertaken to describe, clinically and histologically, the wound healing around endosteal vitreous carbon implants in dogs and to compare the tissues surrounding the implants with those surrounding natural teeth.
METHODS AND MATERIALS Five young (18 to 20 months old) mongrel dogs weighing 18 to 25 pounds were used in this study. The dogs were maintained on a soft diet during the experimental period. In preparation for the insertion of endosteal vitreous carbon implants. the animals were anesthetized by intravenous injection of 1 ml of 1% veterinary sodium pentobarbital for every 5 pounds of body weight. Sixteen vitreous carbon implants were selected. The implants were specially manufactured and
THE JOURNAL
OF PROSTHETIC
DENTlSTRY
AL-SALMAN,
Fig. 1. A diagrammatic illustration shows the method of stabilizing a vitreous carbon implant in the dog.
designed for dog experimentation.* The third mandibular premolars were extracted bilaterally with as little trauma as possible. Each tooth was dissected to the furcation using a carborundum disk and then rotated slightly to loosen the periodontal ligament. The individual roots were then extracted using a root tip elevator. Since the roots and sockets varied in cross section, length, and curvature, two procedures were used to fit the implant into the socket. In the first procedure, the implant was adjusted, using a Carborundum disk, to the cross section and length of the socket. In the second, the socket was surgically contoured to fit the implant using a tapering surgical bur until the appropriate socket gauge could be seated easily. Sterile saline was used to wash the socket and minimize heat generation during cutting. Procedures were performed using sterile surgical techniques to minimize the possibilities of postoperative infection. The implants were ultrasonically cleaned and autoclaved, seated in the socket with gentle finger pressure, and tapped into place. For further stabilization, one end of a 15 mm length of orthodontic wire was inserted into the sleeve of each implant while the other end was bent into a buccolingual groove made on the occlusal aspect of the fourth premolar (Fig. 1). Cold-cure acrylic resin was used to splint and build the occlusion to a functional height. The implants were clinically observed twice a week, at which time the implant sites were brushed and *The Vitredent Los Angeles,
tooth Calif.
mat replacement
system.
Vitredent
Corp..
SAYEGH,
AND
CHAPPELI.
cleaned using saline and a smooth brush. The degree of gingival healing, the texture of the pericoronal mucosal tissue, and the mobility of the implants ~erc observed. The sulcus depth was determined using the dental explorer to investigate the formation of the epithelial attachment. Periapical radiographs were made every 2 weeks to follow-up bone rcmodeling or bone resorption. The animals were killed after 1, 2, and 3 months: and the implant with the adjacent alveolus was sectioned and immediately fixed for histologic studies. Light and scanning electron microscopic techniques were used to observe the tissue responses to the implant. Of particular clinical and histologic interest in this investigation was the degree and type of inflammation in hard and soft tissues adjacent to the implant. Special attention was given to the bone and connective tissues surrounding the vitreous carbon implant. Gingival responses and sulcus depths around the implant necks were evaluated using the periodontal probe. A comparison was made with adjacent natural teeth. which served as controls. RESULTS Healing occurred during the first month uneventfully, with all 16 implants remaining in place. Gingival tissues appeared clinically healthy and showed no evidence of inflammation. The texture of the mucosal tissue around the implants was comparable to that around adjacent natural teeth (Fig. 2). During the fifth week, gingival recession with increasing sulcular depth was observed at the neck of the endosteal vitreous carbon implant. There was little or no resistance to probing. The periodontal probe revealed a deeper sulcus (2.5 mm) around the implant neck as compared to that surrounding adjacent natural teeth (1.5 mm). The continuous gingival recession left 1.5 to 2 mm of the implant exposed to the oral environment by the end of two months (Fig. 3j. At the end of the third month the sulcus depth measured 2.5 to 3 mm, which indicated no epithelial attachment. Gingival recession progressed without evidence of inflammation. leaving 3 to 4 mm of the implants exposed to the oral environment (Fig 4). Although all implants were cleaned twice weekly using saline and a smooth brush, materia alba and food debris were observed on the exposed portion of the vitreous carbon implant. Radiographic examination revealed that the vitreous carbon implant was radiolucent. ‘l‘he radiolucency made it difficult to determine bone remod-
JANUARY
1979
VOLUME
41
NUMBER
I
VITREOUS
CARBON
IMPLANTS
Fig. 2. The mucosa of the implant and the natural teeth, Fig. 3. Gingival recession and exposure of implant after 2 months. Fig. 4. The extent of gingival recession after 3 months. The stabilizer was removed prior to sacrifice.
Fig. 5. A photomicrograph
showing the connective tissue which formed around the implant, Note the directional growth of the tissue which extended into the serrated surfaces of the implant. T, Connective tissue. I, Space where the implant was inserted. Arrow, connective tissue extension. (Original magnification, X 20.)
eling cjr bone resorption occurring around the body of the implant. The microscopic examination of the thin and thick sections of the animal killed at 1 month reveal1 ed no inflammatory response within the newly tissue layer along the formec 3 thick connective
THE JOURNAL
OF PROSTHETIC
DENTISTRY
surface of the implant. Also, within tl le imF 4ant crypt and along the surface of the in rplant, the formation of granulation tissues, charact’ erized by a very vascular, highly cellular connective tissue, was observed. Fibroblasts directly in contac :t with the implant appeared to be somewhat orga nized. The
85
AL-SALMAN,
SAYEGH,
AND
CHAI’PEI
1
Fig. 6. A photomicrograph of an area of the connective tissue described in Fig. 5. Note the well-developed fibroblasts. (Original magnification, x 40.)
Fig. 7. A photomicrograph of the implant and surrounding alveolus as seen with the dissecting microscope 3 months after implantation. Note the close adaptation of the tissues, including bone, to the serrated surfaces of the implant. 1, Implant. (Original magnification, x 10.) nuclei of the fibroblasts were elongated, and their long axes were arranged parallel to the surface of the implant (Figs. 5 and 6). The histologic examination of the animals killed at 3 months showed osseous tissue with trabeculae containing many osteocytes and small narrow spaces. Figs. 7 and 8 reveal bone formation extending into the implant grooves and mechanically locking the implant in place. Bone was observed to have gown in close apposition to the implant surface and appeared healthy and viable.
86
In the decalcified sections of tissue adjacent to the implant, osteocytes were observed within the lacunae, and nutritional canals were observed close to the implant surface. To evaluate the tissue adaptation to the implant surface, histologic sections were also examined using scanning electron microscopy (Figs. 9 and 10). Bone was observed to have grown into the implant surface and into close apposition to the implant. The white tissue in the figures represents the fibrous membrane isolating the bone from the implant. The separation
JANUARY
1979
VOLUME
41
NUMBER
I
VITREOUS
CARBON
IMPLANTS
along the fibrous membrane occurred during preparation of this section. The left half of the fibrous tissue is attached to the surface, and the other half is attached to the bone. The surface of the fibrous membrane was rough and irregular rather than smooth.
DISCUSSION In this investigation the surgical procedure for the placement of the functional implants inta fresh extraction sites required only contouring of the implant to fit the root socket or the surgical contouring of the socket to fit the implant. The implant, when properly adapted to the socket, is self immobilizing, and the splinting to adjacent healthy teeth prevented possible dislodgement while the implants were under function after surgery. The healing of the mucosa and gingival margin occurred uneventfully during the first month with all 16 implants. Vitreous carbon is produced by a process in which all noncarbon components of the resin are driven off and a pure inert carbon is produced.,” This may explain the presence of healthy mucosal tissues with normal texture of the gingival margin around the endosteal vitreous carbon implants. There was no evidence of acute or chronic inflammation. The implant material did not act as an irritant or foreign body to the surrounding tissue. This observation supports and agrees with the work done by Hobkirk.“” Inconsistent with the findings of Grenoble and associates”” and Kim and associates”” was the observation of gradual gingival recession accompanied by a deeper sulcus which was not the same as that around adjacent natural teeth. The epithelium around the implants offered no resistance to probing. This observation supports and agrees with the work done by Skerman, and associates,‘” who concluded from a * study of periodontal implications of the surface characteristics of dental implants that further investigations were necessary to correlate with success or failure of surface characteristics endosteal implant. Thus there is a possibility that failure of endosteal implants may be attributed to a periodontal breakdown of the tissues surrounding the neck portion of an implant. Also, a rough surface could lead to a more rapid and greater accumulation of plaque and resultant calculus, which could act as the initiating factors to periodontal breakdown. The connective tissue has two important functions in wound healing of endosteal vitreous carbon implants. First, in wound repair the connective tissue
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 8. A photomicrograph of the same implant seen in Fig. 7. Note the growth of bone within the connective tissue surrounding the implant, 1.(Original magnification, X25.)
forms granulation tissue. The granulation tissue matures, bridging the space between the implant and the alveolar process to establish tissue integrity. Second, if an implant is in the healing site, the fibroblasts deposit a barrier of fibers which encapsulate the implant and infiltrate through the serrated or untextured surface of the vitreous carbon implant. The extent of the fibrous connective tissue invasion is affected by the biocompatibility of vitreous carbon and the mechanical interaction of the implant with the adjacent tissues. A most remarkable finding was the presence of bone around vitreous carbon implants. The alveolar processes of the mandible and the maxillae exist for the purpose of supporting teeth during function.‘” The alveolar processes resorb after tooth extraction. i’-,i!’ Alveolar bone depends on the stimulation it receives from occlusal function for the preservation of its structure.” As long as the forces are within physiologic limits, increased functional forces lead to formation of new bone, whereas lack of functional stimuli leads to bone atrophy.“” The results of this investigation support Linkow’s and Chercheve’sl’
87
AL-SALMAN,SAYECH.AND CHAPPELI
Fig. 9. An electron micrograph showing the close adaptation of the implant to the alveolus as seen with the scanning electron microscope. I. Implant. A, Alveolus. (Original magnification, X40.)
Fig. 10. An electron micrograph of Fig. 9. 1, Implant. C, Connective tissue. R, Bone. (Original magnification, X 200.) theory that forces transmitted through the connective tissue membrane of endosteal implants will stimulate bone formation and prevent extensive loss of residual alveolar bone by maintaining functional forces.
SUMRY
AND CONCLUSION
Endosteal vitreous carbon implants are patible and were well-tolerated by the process of dogs but were not accepted by the margin and the mucosa. A continuous
88
biocomalveolar gingival gingival
recession with 2 to 3 mm sulcus depth was not similar to that around adjacent natural teeth. There was no epithelial attachment around the neck of vitreous carbon implants, and there was very little or no resistance to probing. The feasibility of using vitreous carbon as it presently exists for the maintenance and preservation of alveolar bone is unfavorable and should be revised. Endosteal vitreous carbon implants require more intense laboratory and clinical studies. Therefore, the practical value of the vitreous carbon
JANUARY1979
VOLUME41
NUMBER 1
VITREOUS
CARBON
IMPLANTS
implant is questionable, and further investigations are needed before vitreous carbon can be declared acceptable in clinical dental practice.
23.
REFERENCES
25.
1. Greenfield, E. J.: Implantation of artificial crown and bridge abutment. Dent Cosmos 55:364, 1913. 2. Venable, C. S., Stuck, W. G., and Beach, A.: The effects on bone of the presence of metals based upon electrolysis. Ann Surg 105:917, 1937. 3. Strock, A. E.: Experimental work on a method for the replacement of missing teeth by direct implantation of a metal support into the alveolus. Am J Orthod 25:467, 1939. 4. Chercheve, R.: Considerations d’actualite sur les implant dentaires et particulaerement endo-osseus. L’Information Dentaire 71:403, 1960. 5. Linkow, I.: The age of endosseous implants. Dent Concepts 8:4, 1966. 6. Linkow, I.: Histopathologic and radiologic studies on endosseous implants. Dent Concepts 11:3, 1968a. new dimension in oral 7. Linkow, I.: The blade vent-A implantology. Dent Concepts 1:3, 196813. 8. Linkow, I.: Endosseous oral implantology: A ‘i-year progress report. Dent Clin North Am 14:185, 1970. 9. Linkow, I., and Chercheve, R.: Theories and Techniques of Oral Implantology, vol. I. St. Louis, 1970, The C. V. Mosby co. 10. Linkow, I.. and Weiss, J. L.: The endosseous blade-A pro
T
he use of dental implants has been thoroughly described in the dental and medical literature since 1891. Throughout this period there has been a desire to replace missing natural teeth with prostheses that could be implanted within the jaws. The development and application of safe and effective dental implants as replacements for natural teeth has long been the main goal of implant dentistry. Yet as great as the need appears to be, safer and more effective human implants are still desired. Dental researchers currently use various classes of materials in their search for a substance which will fulfill the criteria for implants in the oral environment. Among the materials considered are metals,‘.” plastics,‘!,-” and ceramics.” Of these materials, metals have been the most widely used and the most successful to date. Metals are used as both endosteal and subperiosteal implants. One trend of dental implants currently involves the use of a nonmetallic material, the endosteal vitreous carbon implant. Vitreous carbon is a glassy form of pure carbon which is fabricated by thermally degrading a resin under inert atmosphere and then under vacuum, leaving 99.98% pure carbon.” The endosteal vitreous carbon implant can be placed in either fresh tooth extraction sites or in sockets prepared in edentulous ridges.” Voss and Grenoble”’ reported in a 48-month study in humans! an excellent gingival tissue response to This research was supported by the Ministry of Higher Education, Baghdad, Iraq. Condensed from an AMM.S. Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Oral Biology at the University of Missouri, School of Dentistry. *Assistant Professor, Department of Removable Prosthodontics. **Professor and Chairman, Department of Histology. ***Associate Professor and Chairman. Department of Dental Materials.
002%3913/79/010083
+ 07$00.70/O c 1979 The C. V. Mosby Co.
vitreous carbon. They also stated that plaque accumulation on the implants was readily washed away with water and that calculus formation was not evident on the implant surfaces. In addition. the authors reported an apparent remodeling of bone around vitreous carbon implants as determined by histologic and radiographic examination. In contrast to these results, Maropis and associates” reported from their comparative study of vitreous carbon implants in rabbit mandibles that none of their implants were completely biocompatible with rabbit mandibular tissues. Although a different species of experimental animal was employed, they concluded that histologic evidence did not agree with that reported in dogs by Grenoble and Kim.“ Benson,“’ Mooney and Hartmann,“’ and Kadefors and associates’” studied the histologic reactions of vitreous carbon implants and concluded that further investigations were needed to determine the feasibility of using vitreous carbon as a dental implant. The present study was undertaken to describe, clinically and histologically, the wound healing around endosteal vitreous carbon implants in dogs and to compare the tissues surrounding the implants with those surrounding natural teeth.
METHODS AND MATERIALS Five young (18 to 20 months old) mongrel dogs weighing 18 to 25 pounds were used in this study. The dogs were maintained on a soft diet during the experimental period. In preparation for the insertion of endosteal vitreous carbon implants. the animals were anesthetized by intravenous injection of 1 ml of 1% veterinary sodium pentobarbital for every 5 pounds of body weight. Sixteen vitreous carbon implants were selected. The implants were specially manufactured and
THE JOURNAL
OF PROSTHETIC
DENTlSTRY
AL-SALMAN,
Fig. 1. A diagrammatic illustration shows the method of stabilizing a vitreous carbon implant in the dog.
designed for dog experimentation.* The third mandibular premolars were extracted bilaterally with as little trauma as possible. Each tooth was dissected to the furcation using a carborundum disk and then rotated slightly to loosen the periodontal ligament. The individual roots were then extracted using a root tip elevator. Since the roots and sockets varied in cross section, length, and curvature, two procedures were used to fit the implant into the socket. In the first procedure, the implant was adjusted, using a Carborundum disk, to the cross section and length of the socket. In the second, the socket was surgically contoured to fit the implant using a tapering surgical bur until the appropriate socket gauge could be seated easily. Sterile saline was used to wash the socket and minimize heat generation during cutting. Procedures were performed using sterile surgical techniques to minimize the possibilities of postoperative infection. The implants were ultrasonically cleaned and autoclaved, seated in the socket with gentle finger pressure, and tapped into place. For further stabilization, one end of a 15 mm length of orthodontic wire was inserted into the sleeve of each implant while the other end was bent into a buccolingual groove made on the occlusal aspect of the fourth premolar (Fig. 1). Cold-cure acrylic resin was used to splint and build the occlusion to a functional height. The implants were clinically observed twice a week, at which time the implant sites were brushed and *The Vitredent Los Angeles,
tooth Calif.
mat replacement
system.
Vitredent
Corp..
SAYEGH,
AND
CHAPPELI.
cleaned using saline and a smooth brush. The degree of gingival healing, the texture of the pericoronal mucosal tissue, and the mobility of the implants ~erc observed. The sulcus depth was determined using the dental explorer to investigate the formation of the epithelial attachment. Periapical radiographs were made every 2 weeks to follow-up bone rcmodeling or bone resorption. The animals were killed after 1, 2, and 3 months: and the implant with the adjacent alveolus was sectioned and immediately fixed for histologic studies. Light and scanning electron microscopic techniques were used to observe the tissue responses to the implant. Of particular clinical and histologic interest in this investigation was the degree and type of inflammation in hard and soft tissues adjacent to the implant. Special attention was given to the bone and connective tissues surrounding the vitreous carbon implant. Gingival responses and sulcus depths around the implant necks were evaluated using the periodontal probe. A comparison was made with adjacent natural teeth. which served as controls. RESULTS Healing occurred during the first month uneventfully, with all 16 implants remaining in place. Gingival tissues appeared clinically healthy and showed no evidence of inflammation. The texture of the mucosal tissue around the implants was comparable to that around adjacent natural teeth (Fig. 2). During the fifth week, gingival recession with increasing sulcular depth was observed at the neck of the endosteal vitreous carbon implant. There was little or no resistance to probing. The periodontal probe revealed a deeper sulcus (2.5 mm) around the implant neck as compared to that surrounding adjacent natural teeth (1.5 mm). The continuous gingival recession left 1.5 to 2 mm of the implant exposed to the oral environment by the end of two months (Fig. 3j. At the end of the third month the sulcus depth measured 2.5 to 3 mm, which indicated no epithelial attachment. Gingival recession progressed without evidence of inflammation. leaving 3 to 4 mm of the implants exposed to the oral environment (Fig 4). Although all implants were cleaned twice weekly using saline and a smooth brush, materia alba and food debris were observed on the exposed portion of the vitreous carbon implant. Radiographic examination revealed that the vitreous carbon implant was radiolucent. ‘l‘he radiolucency made it difficult to determine bone remod-
JANUARY
1979
VOLUME
41
NUMBER
I
VITREOUS
CARBON
IMPLANTS
Fig. 2. The mucosa of the implant and the natural teeth, Fig. 3. Gingival recession and exposure of implant after 2 months. Fig. 4. The extent of gingival recession after 3 months. The stabilizer was removed prior to sacrifice.
Fig. 5. A photomicrograph
showing the connective tissue which formed around the implant, Note the directional growth of the tissue which extended into the serrated surfaces of the implant. T, Connective tissue. I, Space where the implant was inserted. Arrow, connective tissue extension. (Original magnification, X 20.)
eling cjr bone resorption occurring around the body of the implant. The microscopic examination of the thin and thick sections of the animal killed at 1 month reveal1 ed no inflammatory response within the newly tissue layer along the formec 3 thick connective
THE JOURNAL
OF PROSTHETIC
DENTISTRY
surface of the implant. Also, within tl le imF 4ant crypt and along the surface of the in rplant, the formation of granulation tissues, charact’ erized by a very vascular, highly cellular connective tissue, was observed. Fibroblasts directly in contac :t with the implant appeared to be somewhat orga nized. The
85
AL-SALMAN,
SAYEGH,
AND
CHAI’PEI
1
Fig. 6. A photomicrograph of an area of the connective tissue described in Fig. 5. Note the well-developed fibroblasts. (Original magnification, x 40.)
Fig. 7. A photomicrograph of the implant and surrounding alveolus as seen with the dissecting microscope 3 months after implantation. Note the close adaptation of the tissues, including bone, to the serrated surfaces of the implant. 1, Implant. (Original magnification, x 10.) nuclei of the fibroblasts were elongated, and their long axes were arranged parallel to the surface of the implant (Figs. 5 and 6). The histologic examination of the animals killed at 3 months showed osseous tissue with trabeculae containing many osteocytes and small narrow spaces. Figs. 7 and 8 reveal bone formation extending into the implant grooves and mechanically locking the implant in place. Bone was observed to have gown in close apposition to the implant surface and appeared healthy and viable.
86
In the decalcified sections of tissue adjacent to the implant, osteocytes were observed within the lacunae, and nutritional canals were observed close to the implant surface. To evaluate the tissue adaptation to the implant surface, histologic sections were also examined using scanning electron microscopy (Figs. 9 and 10). Bone was observed to have grown into the implant surface and into close apposition to the implant. The white tissue in the figures represents the fibrous membrane isolating the bone from the implant. The separation
JANUARY
1979
VOLUME
41
NUMBER
I
VITREOUS
CARBON
IMPLANTS
along the fibrous membrane occurred during preparation of this section. The left half of the fibrous tissue is attached to the surface, and the other half is attached to the bone. The surface of the fibrous membrane was rough and irregular rather than smooth.
DISCUSSION In this investigation the surgical procedure for the placement of the functional implants inta fresh extraction sites required only contouring of the implant to fit the root socket or the surgical contouring of the socket to fit the implant. The implant, when properly adapted to the socket, is self immobilizing, and the splinting to adjacent healthy teeth prevented possible dislodgement while the implants were under function after surgery. The healing of the mucosa and gingival margin occurred uneventfully during the first month with all 16 implants. Vitreous carbon is produced by a process in which all noncarbon components of the resin are driven off and a pure inert carbon is produced.,” This may explain the presence of healthy mucosal tissues with normal texture of the gingival margin around the endosteal vitreous carbon implants. There was no evidence of acute or chronic inflammation. The implant material did not act as an irritant or foreign body to the surrounding tissue. This observation supports and agrees with the work done by Hobkirk.“” Inconsistent with the findings of Grenoble and associates”” and Kim and associates”” was the observation of gradual gingival recession accompanied by a deeper sulcus which was not the same as that around adjacent natural teeth. The epithelium around the implants offered no resistance to probing. This observation supports and agrees with the work done by Skerman, and associates,‘” who concluded from a * study of periodontal implications of the surface characteristics of dental implants that further investigations were necessary to correlate with success or failure of surface characteristics endosteal implant. Thus there is a possibility that failure of endosteal implants may be attributed to a periodontal breakdown of the tissues surrounding the neck portion of an implant. Also, a rough surface could lead to a more rapid and greater accumulation of plaque and resultant calculus, which could act as the initiating factors to periodontal breakdown. The connective tissue has two important functions in wound healing of endosteal vitreous carbon implants. First, in wound repair the connective tissue
THE JOURNAL
OF PROSTHETIC
DENTISTRY
Fig. 8. A photomicrograph of the same implant seen in Fig. 7. Note the growth of bone within the connective tissue surrounding the implant, 1.(Original magnification, X25.)
forms granulation tissue. The granulation tissue matures, bridging the space between the implant and the alveolar process to establish tissue integrity. Second, if an implant is in the healing site, the fibroblasts deposit a barrier of fibers which encapsulate the implant and infiltrate through the serrated or untextured surface of the vitreous carbon implant. The extent of the fibrous connective tissue invasion is affected by the biocompatibility of vitreous carbon and the mechanical interaction of the implant with the adjacent tissues. A most remarkable finding was the presence of bone around vitreous carbon implants. The alveolar processes of the mandible and the maxillae exist for the purpose of supporting teeth during function.‘” The alveolar processes resorb after tooth extraction. i’-,i!’ Alveolar bone depends on the stimulation it receives from occlusal function for the preservation of its structure.” As long as the forces are within physiologic limits, increased functional forces lead to formation of new bone, whereas lack of functional stimuli leads to bone atrophy.“” The results of this investigation support Linkow’s and Chercheve’sl’
87
AL-SALMAN,SAYECH.AND CHAPPELI
Fig. 9. An electron micrograph showing the close adaptation of the implant to the alveolus as seen with the scanning electron microscope. I. Implant. A, Alveolus. (Original magnification, X40.)
Fig. 10. An electron micrograph of Fig. 9. 1, Implant. C, Connective tissue. R, Bone. (Original magnification, X 200.) theory that forces transmitted through the connective tissue membrane of endosteal implants will stimulate bone formation and prevent extensive loss of residual alveolar bone by maintaining functional forces.
SUMRY
AND CONCLUSION
Endosteal vitreous carbon implants are patible and were well-tolerated by the process of dogs but were not accepted by the margin and the mucosa. A continuous
88
biocomalveolar gingival gingival
recession with 2 to 3 mm sulcus depth was not similar to that around adjacent natural teeth. There was no epithelial attachment around the neck of vitreous carbon implants, and there was very little or no resistance to probing. The feasibility of using vitreous carbon as it presently exists for the maintenance and preservation of alveolar bone is unfavorable and should be revised. Endosteal vitreous carbon implants require more intense laboratory and clinical studies. Therefore, the practical value of the vitreous carbon
JANUARY1979
VOLUME41
NUMBER 1
VITREOUS
CARBON
IMPLANTS
implant is questionable, and further investigations are needed before vitreous carbon can be declared acceptable in clinical dental practice.
23.
REFERENCES
25.
1. Greenfield, E. J.: Implantation of artificial crown and bridge abutment. Dent Cosmos 55:364, 1913. 2. Venable, C. S., Stuck, W. G., and Beach, A.: The effects on bone of the presence of metals based upon electrolysis. Ann Surg 105:917, 1937. 3. Strock, A. E.: Experimental work on a method for the replacement of missing teeth by direct implantation of a metal support into the alveolus. Am J Orthod 25:467, 1939. 4. Chercheve, R.: Considerations d’actualite sur les implant dentaires et particulaerement endo-osseus. L’Information Dentaire 71:403, 1960. 5. Linkow, I.: The age of endosseous implants. Dent Concepts 8:4, 1966. 6. Linkow, I.: Histopathologic and radiologic studies on endosseous implants. Dent Concepts 11:3, 1968a. new dimension in oral 7. Linkow, I.: The blade vent-A implantology. Dent Concepts 1:3, 196813. 8. Linkow, I.: Endosseous oral implantology: A ‘i-year progress report. Dent Clin North Am 14:185, 1970. 9. Linkow, I., and Chercheve, R.: Theories and Techniques of Oral Implantology, vol. I. St. Louis, 1970, The C. V. Mosby co. 10. Linkow, I.. and Weiss, J. L.: The endosseous blade-A pro
