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| EDITORIAL COMMENTRY |
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| Year : 2014 | Volume
: 4
| Issue : 1 | Page : 1-2 |
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Bone grafting … a boon?
Rajiv S Khosla
BDS and Diplomate of the International Congress of Oral Implantologists,Mumbai, India
| Date of Web Publication | 19-Apr-2014 |
Correspondence Address:
Rajiv S Khosla
BDS and Diplomate of the International Congress of Oral Implantologists,Mumbai
India
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/0974-6781.130941
How to cite this article:
Khosla RS. Bone grafting … a boon?. J Dent Implant 2014;4:1-2 |
It was as recently as during my undergraduate years in the late 1970s, before the renaissance of dental implants, that much of preprosthetic surgery was aimed at simply building a stable base for a denture in patients who had experienced severe atrophy of their jaws. As we know, our jaws have the amount of the bone that they do only due to the presence of existing teeth, and the fact that those teeth are under continuous function. Once teeth are lost, the jaws quickly atrophy to a level of the basal bone. In cases of a complete loss of teeth, this can leave behind only a narrow hoop of bone in the mandible or a flat pancake of bone in the maxilla. Extravagant and often complicated hospital based procedures were devised to address this atrophy and attempt to rebuild the jaws to a point where the patient could comfortably wear a stable denture and have confidence during normal masticatory function. These more severe methods are nearly absent from today's treatment plans. Today, we have the ability to grow bone where needed. This not only gives us the opportunity to place implants of proper length and width, it also gives us a chance to restore functionality as well as aesthetics.
Interest in bone substitutes for alveolar ridge augmentation or preservation arose in the early 1980s alongside the development of endoosseous dental implants. Although first studies regarding bone substitutes date back to 1920 by Albee, until the eighties, there were very few further studies.
The term "bone graft." was defined by Muschler (Bauer, 2000) as "any implanted material that alone or in combination with other materials promotes a bone healing response by providing osteogenic, osteoinductive, or osteoconductive properties." A bone graft is a surgical procedure that not only replaces missing bone, but also helps the body to regrow its own lost bone. Over time the newly formed bone will replace much of the grafted material. A bone graft or bone augmentation procedure is not always the rule of thumb, but there are a number of factors that can increase one's potential need for this type of adjunctive procedure. For example, patients who have postponed their decision to replace a missing tooth may find that significant bone loss has occurred as a consequence. A foundation of adequate bone is an absolute necessity in order for a dental implant to be successful. Other circumstances like congenital birth conditions, previous injuries, defects resulting from cysts or tumor surgery and advanced gum disease can leave the bone less likely to support dental implants.
There are several different types of materials to choose from. These include autogenous bone grafts taken from the patient's own body or allografts which are human bone grafts donated by another person and usually provided by tissue banks. Xenografts are bone grafts from other species, which can be bovine, equine or porcine. Alloplasts are synthetic bone graft materials. Growth factor enhanced grafts are produced using recombinant DNA technology to manufacture human proteins (growth factors) that actually signal the body to form bone. Platelet derived human growth factors or bone morphogenic proteins, in conjunction with a carrier medium, such as collagen have recently been developed for dental bone grafting (JDI Vol. I - p. 42). Live mesenchymal stem cells that are crucial to the formation of new bone, are now able to be preserved in an allograft (human) material. (Editorial - JDI Vol. III - p. 85). Most common bone grafting required involves one or a combination of the following three outpatient procedures: the alveolar ridge preservation graft (JDI Vol. I - p. 97) or socket graft, the autogenous ramus/chin graft or block bone graft (JDI Vol. III - p. 81) and the subantral graft or sinus lift procedure (JDI Vol. I - p29 and JDI Vol. II - p. 26).
The bone substitute needed for each bone regeneration procedure must be selected based on the individual's characteristics, and the surgical procedure itself. Factors such as the osteogenic potential of the host residual bone, systemic health of patients, and morphology of the defects, will delimit the ideal bone substitute for each situation. For example in sinus augmentation, allografts, xenografts and synthetic calcium phosphates have been used as alternative to autografts with high rate of implant success and survival. On the other hand, when major alveolar ridge augmentations are required autograft onlay block are the most predictable biomaterials, although autograft granules mixed in different proportions with anorganic bovine bone have also a high rate of success.
The principles involved in successful bone grafts include osteoconduction (guiding the reparative growth of the natural bone), osteoinduction (encouraging undifferentiated cells to become active osteoblasts), and osteogenesis (living bone cells in the graft material contribute to bone remodelling). Osteogenesis only occurs with autografts. Initially, bone-grafts mechanically prevent the collapse of the surrounding tissues, whether bone or soft tissue. Then, through a process called "guided tissue regeneration," the human body is fooled biochemically to recognize the graft as natural bone and over time resorbs and replaces it with the patient's own native bone. Recent developments in bone grafting techniques have made implant treatment possible in cases that would have been impossible just a few years ago. There are potential downsides to bone grafting in conjunction with dental implants. The process of bone grafting and the ensuing healing period may add significant time to the procedure. The second problem is the increased cost of these procedures. Also, in some instances bone grafts fail (mal-union, delayed union, or nonunion of the donor bone graft to the recipient bone site) and must be removed. Lack of adequate bone growth in the bone graft replacement material could also result in failure.
Tooth loss among the elderly population will create some growth in the $3 billion global dental implant market despite the current recession, according to "Implant-Based Dental Reconstruction: World Dental Implant and Bone Graft Market, 3 rd Edition" by premier life sciences market research publisher Kalorama Information, though not the impressive double-digit growth rates of prior years. The recession is expected to pose a challenge for future sales of dental implants and equally impacted is the dental bone graft market, which has a growth trajectory proportional to growth in the dental implant market.
"The Indian Markets for Dental Bone Grafts and Other Biomaterials Report" published in October 2012 states that in 2011, the Indian dental bone graft substitutes (BGS) and other biomaterials market increased by 38.4% over the previous year. The markets in this report include BGS and dental membranes. The growth of this market is mainly due to the increasing number of dental implant placements. The undersaturated state of the Indian dental BGS and other biomaterials market will result in double-digit growth over the 2011-2018 forecast period. In addition, the emergence of new products will contribute to the market's strong growth. The overall market is still relatively young in India and is expected to continue to grow as a result of the aging Indian population (Editorial - JDI Vol. I - p. 41) and as new competitors enter the market. Further growth in the overall market is fuelled by the Indian government's efforts to improve healthcare coverage across the country, and by the increasing disposable income of Indian citizens.
Although several bone graft techniques as well as nongrafting treatment options can be considered well documented for different indications (Jensen and Terheyden, 2009), there is significant lack of comparative effectiveness research to guide decision making in oral bone graft surgery. While some surgical options have been compared in randomized or nonrandomized controlled trials, evidence on other treatment alternatives is based on between-study comparison. Even indirect comparison of study results could not provide further evidence. No long-term investigation comparing all available treatment options for any completely or partially edentulous situation has been identified. According to Esposito et al. 2009, in order to understand when bone augmentation procedures are needed and which are the most effective techniques for the specific clinical indications, larger and well-designed long-term trials are needed and hence it is difficult to provide clear indications with respect to which procedures are actually needed. Simpler and less invasive procedures with least risk of complications that reach their goals within the shortest time frame should get priority.
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Rajiv S Khosla
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