Autogenous and Allogeneic Bone Grafts in Periodontal Therapy

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osseous coagulum (Evans, 1981), bone blend (Froum et al, 1975), intraoral cancellous bone and marrow (Ross and Cohen, 1968; Hiatt and Schallhorn, 1973; Hawley and Miller, 1975; Hiatt et al., 1978; Listgarten and Rosenberg, 1979; Langer et al., 1981), iliac cancellous bone and marrow autograft (Dragoo and Sullivan, 1973; Hiatt et al., 1978), iliac cancellous bone and marrow allograft (Hiatt et al., 1979; Listgarten and Rosenberg, 1981), and undemineralized FDBA (Moomaw, 1978). Currently, only a notch placed in the most apical level of calculus on the root surface is considered scientifically valid proof of regeneration of an attachment apparatus (Cole et al., 1980; Froum et al, 1983; Dragoo and Kaldahl, 1983; Bowers et al., 1989a, b, and c). Using this criterion, new bone, cementum, and periodontal ligament have been identified following grafts of osseous coagulum-bone blend (Froum et al., 1983) and DFDBA (Bowers etal, 1989a, b, and c). C. Bone Induction It has been stated that there is "little indication that (periodontal bone) grafts of cortical or cancellous bone have any inductive effect on the formation of new bone. Also, there is little reason to believe that such bone grafts would stimulate connective tissue attachment to the root surface" (Egelberg, 1987). This concept was evaluated in a study by Bowers et al. (1989b). They compared the healing of intraosseous defects with and without the placement of DFDBA in defects about teeth that received coronalectomy and were completely covered by soft tissue. The most apical level of calculus on the root served as a histologic reference point to measure periodontal regeneration in 30 grafted and 19 nongrafted defects. Results indicated that in the submerged environment, regeneration was possible with and without the placement of a bone graft. However, more new attachment apparatus formed in grafted than nongrafted sites. In addition, new bone, new cementum, and periodontal ligament occurred more frequently in grafted than nongrafted sites. These results strongly sug- gest that bone grafts do have an inductive effect on the periodontium. D. Healing Sequence The healing sequence of an autogenous periodontal bone graft has been identified as initiation of new bone formation at 7 d, cementogenesis at 21 d, and a new periodontal ligament at 3 months (Dragoo, 1972). By 8 months, the graft should be incorporated into host bone with functionally oriented fibers coursing between bone and cementum. Maturation may take as long as 2 years (Dragoo, 1972; Dragoo and Sullivan, 1973). E. Root Resorption and Ankylosis Because granulation tissue derived from bone may induce root resorption and ankylosis, the use of bone grafts has been questioned (Karring et al., 1980). Root resorption is reported as a sequela of osseous grafting in humans but appears to be a significant disadvantage only with fresh iliac cancellous bone and marrow (Schallhorn et al., 1970; Schallhorn, 1972; Dragoo and Sullivan, 1973; Hoffman and Flanagan, 1974; Hiatt et al., 1978). Clinical evidence of root resorption was noted in 7 of 250 sites (3% in one reported series (Dragoo and Sullivan, 1973) and 16 of 275 sites (5%) in another (Hiatt et al., 1978). Freezing seems to attenuate this problem (Schallhorn, 1972). Recently, Bowers and co-workers reported on a series of 62 cases grafted with DFDBA and removed en bloc at 6 months for histologic observations (Bowers et al., 1989b and c). Extensive root resorption was not observed. Because this phenomenon has been observed only with fresh material, viable marrow cells may play an etiologic role (Ellegaard, 1976). The most probable cause of root resorption is poor postsurgical plaque control with subsequent chronic gingival inflammation (Dragoo and Sullivan, 1973). This hypothesis has been strengthened by histologic findings that connective tissue in resorptive defects always contained an infiltrate of inflammatory cells (Ellegaard, 1976). Root re- Downloaded from cro.sagepub.com by guest on January 10, 2013 For personal use only. No other uses without permission. 343
sorption and ankylosis following bone grafts are more prevalent in animal models (Ellegaard et al., 1973 and 1976; Karring et al, 1980 and 1984; Nyman et al, 1980) than they are in humans and may be a function of the healing potential animal model (Sonis et al, 1985; Aukhil etal, 1990). Apical migration of junction epithelium between the alveolar bone and the root surface has been offered as an explanation of why resorption only infrequently takes place after regeneration attempts with bone grafts (Listgarten and Rosenberg, 1979; Karring et al, 1980; Caton and Zander, 1976; Moskow etal, 1979). The junctional epithelium was specifically located in 74 human biopsies where bone grafting was performed (Bowers et al, 1982). The junctional epithelium was located apical to the alveolar crest in 14 (19%) sites. In an additional 32 graft sites, Bowers et al (1989c) showed that grafted sites consistently formed a new attachment apparatus. The junctional epithelium proliferated apically, but the epithelium was rarely observed apical to the level of active bone formation. Junctional epithelium was never observed beyond the level of new cementum formation (Bowers et al, 1989c). Authors reporting epithelial migration between the grafted site and the root surface also report chronic inflammatory cells adjacent to the epithelium (Hiatt et al, 1978) or extending into the marrow spaces (Moskow et al, 1979). Poor plaque control is therefore a likely explanation as proliferation of epithelium is more extensive and rapid in surgical sites with no postoperative plaque control than in areas where bacterial deposits have been removed (Yumet and Poison, 1985). VI. TISSUE BANKING AND FDBA The possibility of disease transfer with bone allografts is unlikely if the material is procured and processed by using established tissue banking protocols (Friedlaender, 1987; American Association of Tissue Banks, 1984). If exclusionary techniques such as medical and social screening, antibody testing, direct antigen tests, other serologic tests, bacterial culturing, autopsy, and follow-up studies of grafts from the same donor are 344 used, the possibility of disease transfer are approximately one in 2 million (Buck et al, 1989). Freezing the bone allograft reduces the risk to one in 8 million (Buck et al, 1990). An estimated 40,000 periodontal grafts of mineralized and demineralized bone are performed annually (Mellonig, 1991). There are no reported cases of disease transfer with processed (treatment with virucidal agents and demineralization in hydrochloric acid) FDBA. Concerns with disease transfer have led some tissue banks to sterilize the bone allograft with irradiation or ethylene oxide. Irradiation of a bone allograft is reported both to markedly attenuate (Buring, 1967; Towle et al, 1987; Munting et al., 1988) and not to affect (Wientroub et al, 1988) bone induction. Furthermore, the currently used dose of 1.5 Mrad will not reliably inactivate HIV in bone allografts with an acceptable safety margin (Conway et al, 1990). There is little question that ethylene oxide sterilization renders a bone allograft noninfectious (Eastlund et al, 1989). However, like irradiation, ethylene oxide may interfere with bone induction (Zislis et al, 1989). Residual levels of ethylene oxide in the graft have been shown to be toxic to fibroblasts and cause morphologic changes that may or may not be reversible (Kudryk, 1990). Others have found ethylene oxide sterilization to be acceptable and safe (Prolo et al, 1980). The processing of a bone allograft for dental use will usually include the following steps (Mellonig, 1991): 1. Cortical bone is harvested in a sterile manner within 12 h of death of the donor. Cortical bone is less antigenic than cancellous bone (Friedlaender et al, 1976) and has a higher concentration of bone-inductive proteins (Urist and Do well, 1968; Urist et al, 1970). 2. The bone is rough cut to 0.5 to 5 cm and immersed in 100% ethanol for 1 h. Viral infectivity is undetectable within 1 min of treatment (Resnick et al, 1986), and the ethanol completely penetrates through the cortical bone (Prewitt et al, 1991). 3. The bone is frozen. Freezing decreases the risk of disease transfer (Buck et al, 1990). 4. The cortical bone is ground to a final par- Downloaded from cro.sagepub.com by guest on January 10, 2013 For personal use only. No other uses without permission.
Page 1 and 2: Critical Reviews in Oral Biology &
Page 3 and 4: Bowers et ai, 1982; Pierce, 1982; D
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Page 7 and 8: this approach when used by differen
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Page 17 and 18: Ellegaard, B., I. M. Nielsen, and T
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Autogenous and Allogeneic Bone Grafts in Periodontal Therapy

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