Alloplastic bone grafts in periodontal surgery

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1 Review Article Alloplastic bone grafts in periodontal surgery M. Dhanvanth 1, Dhanraj Ganapathy 2, Ashish R. Jain 2 * ABSTRACT Bone grafts are used as a filler and scaffold to facilitate bone formation and promote wound healing. These grafts are biorestorable and have no antigen-antibody reaction. These bone grafts act as a mineral reservoir which induces new bone formation. Bone grafting is a surgical procedure that replaces missing bone with material from patient s own body, an artificial, synthetic, or natural substitute. Bone grafting is possible because bone tissue has the ability to regenerate completely if provided the space into which it has to grow. As natural bone grows, it generally replaces the graft material completely, resulting in a fully integrated region of new bone. The most serious consequence is the loss of the periodontal support structure, which includes cementum, the periodontal ligament, and alveolar bone. Conventional periodontal treatments, such as root planing, gingival curettage, and scaling, are highly effective at repairing disease-related defects and halting the progression of periodontitis. These are important steps; however, the conventional therapies do relatively little to prompt the regeneration of lost periodontal supporting structure. The more effective techniques that predictably promote the body s natural ability to regenerate its lost periodontal tissues, particularly alveolar bone still need to be developed. Bone grafting is the most common form of regenerative therapy today and is usually essential for restoring all types of periodontal supporting tissue. The histological evidence in humans indicates that bone grafting is the only treatment that leads to regeneration of bone, cementum, and a functionally oriented new periodontal ligament coronal to the base of defect. KEY WORDS: Advantages, Bone grafts, Disadvantages alloplastic bone grafts, Periodontal disease INTRODUCTION The disease which is caused periodontally in the oral cavity is one of the most prevalent widespread infections worldwide. The most risky situation is where there is the loss of the periodontal support structure that involves cementum, periodontal ligament, and alveolar bone. The proper periodontal treatments are available such as root planing, gingival curettage, and scaling and are maximum effective at preventing disease producing defects and altering the transformation of periodontitis. These are important steps; however, the conventional therapies do relatively little to prompt the regeneration of lost periodontal support structure. In fact, studies indicate that they typically result in the development of a long junctional epithelium between the root surface and gingival connective tissue rather than the regrowth Access this article online Website: jprsolutions.info ISSN: of tissue that restores the architecture and function. Thus, more effective techniques that predictably promotes the body s natural ability to regenerate its lost periodontal tissues, particularly alveolar bone still need to be developed. The bone grafting is the important form of common regenerative therapy at present and is usually important for preventing all types of periodontal supporting structure. Till date, the histological information in humans explains that the bone grafting is the only prior treatment that transforms to regeneration of bone, cementum, and functionally associated new periodontal ligament above to the base of a long back osseous defect. [1] Bone Graft A bone graft is a surgical procedure used to fix problems with bones or joints. Bone grafting is the procedure of transplanting the bone structures which is advantage in repairing bones that are damaged from trauma. A bone graft may consume with a void where bone is absent and helps to provide the structural function. [2] 1 Department of Prosthodontics, Saveetha Dental College, Saveetha University, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India, 2 Department of Prosthodontics, Saveetha Dental College, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Chennai, Tamil Nadu, India *Corresponding author: Dr. Ashish R. Jain, Department of Prosthodontics, Saveetha Dental College, Saveetha University, Saveetha Institute of Medical and Technical Sciences, Saveetha University, Poonamalle High Road, Chennai , Tamil Nadu, India. Phone: dr.ashishjain_r@yahoo.com Received on: ; Revised on: ; Accepted on:

2 Classification of Bone Grafts Human bone Autogenous grafts (autografts). Extraoral Iliac crest graft, Rib graft, Calvarial graft, Tibial graft, Fibular graft, Ulnar graft Intraoral Allogeneic grafts (allografts) Fresh frozen bone Freeze-dried bone allografts Demineralized freeze-dried bone allografts Bone substitutes Xenogeneic grafts (xenografts) Bovine-derived hydroxyapatite Coralline calcium carbonate Alloplastic grafts (alloplasts) Polymers Bioceramics Tricalcium phosphate Hydroxyapatite - dense, non-porous, nonresorbable, porous Non-resorbable Hydroxyapatite derived at low temperature (xenograft) Resorbable Bioactive glasses. Ideal Characteristics of a Bone Graft Non-toxic Non-antigenic Resistant to infection No root resorption or ankylosis Strong and resilient Easily adaptable Readily and sufficiently available Minimal surgical procedure Stimulates new attachment The Indications for Bone Grafts Deep intraosseous defects The deeper the defect, the greater amount of bone fill that can be expected; at the same time, the residual defect may be significant. It is the opinion of many clinicians that the greater the number of osseous walls and the greater the support and containment for the graft material, the greater will be the bone fill. The degree of regeneration in an osseous defect of a given volume and morphology varies directly with the adequacy of the soft tissue cover and with the surface area of the vascularized bony walls lining the defect; it varies inversely with the root surface area. Therefore, a three-wall defect should heal with more bone fill than a two-wall or a one-wall lesion, and a one-wall defect should heal better than a furcation defect. The intrabone defects are affected by periodontal abscesses or pulpal pathogenesis that responds favorably with bone consumption without a graft and following considered immediately with emergency or endodontic therapy. Tooth retention The bone grafts are used with restorative functional stability and to a degree as to eliminate the need for extraction. Support for critical teeth The teeth may be loosened by loss of alveolar support can be advantage from the use of bone grafts and may be the chance for the abutment tooth or those teeth that are risk for the preservation of structural integrity. Bone defects associated with juvenile periodontitis The extensive lesions have been reported that the response is very advantage to bone grafting and mainly when grafting is joined with an antibiotic such as tetracycline. Esthetics (shallow intraosseous defects) The resection of shallow intraosseous defects in the anterior region of the mouth by osteoplasty/ostectomy followed by an apically positioned flap to eliminate the periodontal pocket will result in gingival recession and a long clinical crown. This may be esthetically unacceptable. The use of osseous grafts to reconstruct bone architecture allows placement of the gingival margin as close as possible to its original position. Successful healing will result in minimal apical displacement of the gingival margin. Furcation defects This indication applies mainly to Class II furcation defects. Bone grafts, especially if used in conjunction with guided tissue regeneration, have proven to be the therapeutic modality of choice for treating this type of lesion. [3] Alloplastic Bone Graft Alloplastic bone grafts consist of materials that are synthetic, inorganic, biocompatible, and/or bioactive bone graft substitutes, which are claimed to promote bone healing through osteoconduction. Alloplasts are usually conductive with bone without any induction of bone and osteogenic capacity on their own and have been used frequently for periodontal regeneration. The available alloplastic materials are plaster of Paris, polymers, calcium carbonate, and ceramics. 2384

3 The calcium phosphate biomaterials are used mainly as the replacement of graft materials of bone in periodontal regeneration as they have identical composition to bone substance, are osteoconductive form bone apatite-like material or carbonated HA and form a very strong bone-calcium phosphate biomaterial interface. Ceramics can be classified into resorbable (e.g., tricalcium phosphate and resorbable HA) and non-resorbable (dense HA, porous HA, and bioglass). [2] Bioglass developed by Hench is one of the latest and promising substitutes for bone graft materials. Other alloplastic materials are as follows: Calcium Phosphate Ceramics Larger number of ceramics is available; the calcium phosphate type has been of particular interest because of the close chemical and crystal resemblance of some of these materials to bone mineral. Commonly used calcium phosphate ceramics for periodontal regeneration are essentially of two types: The relatively non-resorbable HA (Ca 10 (PO 4 ) 6 (OH) 2 ) or the resorbable tricalcium phosphates (Ca 3 (PO 4 ) 2 ). Polymethylmethacrylate (PMMA) and Polyhydroxyethylmethacrylate (PHEMA) Polymers A biocompatible microporous polymer containing PMMA, PHEMA, and calcium hydroxide is available as a bone grafting material for the treatment of periodontal defects (HTRTM Synthetic Bone- Bioplant, Norwalk, CT). This composite is prepared from a core of PMMA and PHEMA with a coating of calcium hydroxide. It forms calcium carbonate apatite when introduced into the body and interfaces with bleeding marrow. [4] Hydroxyapatite The hydroxyapatite substances used in cyclic ontology are differentiated into two forms which are particulate non-resorbable ceramic form and a particulate resorbable non-ceramic form. In controlled clinical studies, grafting of intrabony periodontal lesions with HA resulted in an attachment level gain of mm which was greater as compared with non-grafted surgically debrided controls by Galgut in Synthetic hydroxyapatite, Ca 10 (PO 4 ) 6 (OH) 2, has been available for more than 30 years. It is the primary mineral found in bone. Synthetic hydroxyapatite can be found as porous or non-porous and in ceramic or non-ceramic forms. The advantages of using hydroxyapatite are the reactions which are immune can be eliminated, post-operative structural changes, and volume lowered and do not form if small blocks, and contents are frequently arranged during surgery, the post-operative absorption of hydroxyapatite if present is slightly slowed and is replaced by the bone, and fixation of cement is formed on the region of hydroxyapatite particles that eliminate the harmful actions of polyethylene particles of cement surface. The clinical disadvantages of hydroxyapatite particles are that they tend not to stay in place in a bleeding site, and there is a relatively slow restoration of bone within the assemblage of particles. The polycrystalline form of ceramic is purely in quantity and hydroxyapatite is non-absorbable, osteoconductive with low microporosity, and initiate early as inert biocompatible fillers. The several and various forms are present of hydroxylapatite: a. The coralline porous non-resorbable hydroxylapatite is a replica of a marine coral skeleton, Porites. b. The resorbable non-ceramic hydroxylapatite is highly microporous, non-sintered (non-ceramic), composed of small particles measuring mm (35 60 mesh), with a controlled, predictable rate of resorption. c. Nanocrystalline hydroxyapatite nanoparticular hydroxyapatite not only provides the benefits of traditional hydroxyapatites but also resorbs. d. FHA biomaterial is the natural architecture of some calcified algae offer a surface that is similar to that of bone. [5] Tricalcium Phosphate Tricalcium phosphate has been shown to stimulate bone formation and is comparable or in most cases superior in this regard to HA as described by Fetner. It has been shown to stimulate bone formation to a greater extent than HA, but to a much lesser extent than bioglass as described by Wilson and Low in Cultured human fibroblasts have been demonstrated to attach readily to the surface of calcium phosphate ceramics. HA acts as an amphoteric ion exchanger. Selective accumulation of calcium and phosphate ion occurs as a consequence of the negative charges on the HA surface. This leads to the formation of more apatite and stimulates the formation of new bone. Resorption of tricalcium phosphate grafts is thought to be dependent on dissolution by biological fluids in the absence of osteoclasts around the materials and by the presence of osteoclast-mediated resorption based on the osteoclast-like giant cells in defect areas. Tricalcium phosphate biomaterials have been used in human clinical studies to repair periapical and marginal periodontal defects. [6] Plaster of Paris Plaster of Paris is biologically compatible and porous and also it allows the fluid to exchange in which prevention of flap necrosis takes place. The plaster of Paris resorption takes place incompletely 1 2 weeks. The useful advantages in human studies have not been proved. Hard Tissue Replacement Polymer Hard tissue polymerization is non-resorbable, microporous biocompatible composite of polymethylmethacrylate and polyhydroxyethylmethacrylate, a resorbable polylactic acid polymer. This material has been used in 2385

4 the fabrication of contact lenses, lens transplants, and prosthetic heart valves over many years. The polymer does not produce an inflammatory or immune response in contact with bone or soft tissue as described. Bioactive Glass and Ceramics Bioglasses are composed of Si-CaO-Na 2 O-P 2 O 5 and are resorbable or not resorbable depending on the relative proportion of these components. When bioglasses are exposed to tissue fluids, a double layer of silica gel and calcium phosphate is formed on their surface. On the layer of it, the material elevates absorption and concentration of proteins used by the osteoblasts to produce an extracellular bone matrix which may theoretically promote bone formation as described by Henchand in They have been extensively used in conjunction with medical and dental implants because they develop a layer of hydroxyl carbonateapatite on their surface following exposure to body fluids. When used on the surface of metal implants, this layer incorporates collagen fibrils and in this way produces a mechanically strong bond between implant and the adjacent bone surface as described by Simonds RJ et al in [7] Porous Titanium Granules (PTG) The Tigran PTG is irregularly shaped and porous granules manufactured using commercially pure titanium. The granules are between 0.7 mm and 1.0 mm. When they are mixed with the patient s blood or with a saline solution, the granules attach to each other due to the capillary force. The surface layer of titanium is very thrombogenic in nature in which it accommodates the formation of stabilizing blood clots around the granules. The granules that have a porosity of about 80% and an osteoconductive surface structure, imitate properties of human bone, and create scaffolding for bone generation that stimulates osteoblast colonization and osseointegration. The granules are non-resorbable and keep their volume during the operation and the entire healing period which ensures mechanical stability and a desired esthetic result. Tigran PTG is easy to use. No special tools are needed. When osseointegration is completed, common drilling techniques are used when an implant has to be placed in the treated area. [8] Demineralized Dentin Matrix The component of dentin that is organic in nature which considered for appropriately 15% of dentin weight which is mainly Type I collagen which is a component of bone. The dentin layer that consists of the bone morphogenetic proteins that elevate the various differentiation of stem cells of mesenchyme into chondrocytes and the enhancement of bone formation, non-collagen proteins such as osteocalcin and osteonectin, which have been implicated in calcification and dentin-specific proteins including dentin phosphoprotein, also known as phosphophoryn, and dentin sialoprotein. [9] DISCUSSION The bone grafting is one of the most commonly used methods to cure high bone defects in periodontal regenerative therapy. Moreover, it is a fact that not all bone grafting substances are supportive in the production of new periodontal attachment features there are conclusive studies that periodontal regeneration can be successful with replacement of bone grafts in the humans. The synthetic biomaterials of alloplasts were produced to eradicate the disadvantages of autografts that are implemented in different forms with various physiological and chemical properties that can be degradable and non-degradable. The autografts considered to be the active standard by the production of osteogenic cells with osteoinductive growth factors and an osteoconductive scaffold and all that is important for new bone growth but involve the disadvantages of morbidity at the productive site and lowered availability. [10] The allografts, xenografts, and tissue engineered grafts have considered to be low compared to autografts. The new strategies such as the gene therapy and polytherapy using the scaffolds are used for healing promotion factors and stem cells, and later, the three-dimensional printing used in their preliminary levels but can be opened with new insights shortly. The loss of alveolar bone is one of the characteristic signs of destruction in periodontal disease and is commonly considered to present the anatomical sequence to the apical widespread of periodontitis. The bone grafts and the synthetic contents of bone grafts have been used as the important factor to involve the therapeutic sites. The most commonly used alloplastic materials are hydroxyapatite, tricalcium phosphates, and bioactive glasses. [11] Clinical Objectives of Bone Grafting for Periodontal Regeneration The objectives of bone grafting procedures for patients with periodontitis are as follows: 1. Probing depth reduction 2. Clinical attachment gain 3. Bone fill of the osseous defect 4. New bone, cementum, and periodontal regeneration 5. Ligament. [12] Characteristics of a bone graft Non-toxic Non-antigenic Resistant to infection No root resorption or ankylosis 2386

5 Strong and resilient Easily adaptable Readily and sufficiently available Minimal surgical procedure Stimulates new attachment. [13] Advantages of bone grafts 1. Regeneration of the attachment apparatus is possible. Reconstruction of lost bone, cementum, and periodontal ligament has been adequately documented with autogenous and allogeneic graft materials. 2. By reconstructing the periodontium, it is possible to reverse the disease process. 3. Increased tooth support, improved function, and enhanced esthetics are concomitant results of successful bone graft therapy. 4. Bone grafts have application for all categories of intraosseous defects and certain furcation defects. This is in contrast to other forms of regenerative therapy. 5. Idealistic therapeutic objectives may be achievable. With the advent of growth factors to augment the osteogenic potential of current or future graft materials, complete disease reversal is a realistic goal. [14] Disadvantages of bone grafts 1. Bone graft therapy involves additional treatment time. Because of graft procurement and/or preparation, as well as placement, the time allotted to the surgical procedure must be lengthened. For the clinician inexperienced in regenerative periodontal therapy, the learning curve and the subsequent increase in treatment time will be significant. 2. Autografts require the removal of host donor tissue. Unless bone can be removed from within the primary surgical site, a secondary surgical site, either extraoral or intraoral, is necessary. The risks of any surgical procedure will apply here as well. In addition, the quantity of intraoral bone to fill multiple or deep defects is often lacking. The resorption of root and the ankylosis are the major problem identified with new iliac cancellous bone and marrow. 3. The availability and with added features of bone allograft are ongoing problems. Patients and clinicians fears of disease transfer can be ameliorated by reference to the scientific literature. 4. Additional post-operative care is often necessary with bone graft therapy. This can range from technical problems to the management of soft tissue defects associated with wound healing. 5. Bone grafts take a long time to heal. As much as 2-year post-operative interval may be necessary before there is final radiographic resolution of the defect. Although most patients can receive restorative care 6 months following treatment, partial bone fill or delayed healing may delay needed restorative care. 6. Bone graft therapy is not routinely predictable in the hands of all practitioners. Bone grafts are highly successful for those practitioners who have taken the time and effort to master this technique-sensitive therapy. 7. Bone graft adds greater expense to the therapy. Economic considerations involve the cost of procurement or of the material itself, additional surgical treatment time, and post-operative maintenance treatment. 8. Multistep therapy is sometimes necessary, either to regraft residual osseous defects, where additional bone fill is possible and feasible, or to eliminate the residual osseous defect by resection. [15] Requirements for a Successful Graft The most important surgical considerations in performing bone grafts for periodontal regeneration are as follows: Patient selection Attention to patient selection is particularly important in the use and success of regenerative procedures, particularly bone grafts. The patient must demonstrate a high level of motivation and ability to remove plaque effectively on a daily basis. The patient must also show a commitment to keeping the often lengthy and rigorous appointments necessary for periodontal maintenance. During these, baseline records and a plaque index assessment help to determine the patient s progress. Other factors that must be considered are the patient s health, emotional status, habits (particularly smoking), and the ability to tolerate lengthy dental appointments. If any of these are unfavorable, bone grafts may be contraindicated. Material selection Matching the contours of a defect to appropriate treatment is also clearly important for any regenerative or augmentation treatment. For instance, the more walls of bone that are present in the defect site, the better a graft s chance for success. Many failures are due to the selection of a treatment for a defect that will not respond well to the procedures. [16] Proper Flap Reflection and Wound Stability Full-thickness flaps are generally recommended to provide access to periodontal defect sites. Internally beveled scalloped incisions with full gingival retention should be used so that the site can be completely closed when the surgery is concluded. Vertical releasing incisions should be used as necessary to allow access to the defect. Improper flap design can 2387

6 result in compromised blood supply to an underlying graft. As an alternative to the traditional approach of positioning the flap margin so it directly approximates the healing area, a coronally positioned flap procedure, which positions the flap margin away from the critical healing area and coronal to the cementenamel junction, has been shown to provide better regenerative results for Class II and Class III furcation defects. Crown-attached sutures have also been shown to stabilize the flap margin better and prevent it from receding. [17] Revascularization The underlying bone that receives the graft material must exhibit several marrow spaces and a good blood supply because prompt revascularization is crucial to ensure the survival of undifferentiated mesenchymal cells and osteoblasts at the site. For the largest number of osteocytes in graft material to survive and provide osteogenesis, early vascularization of the graft is crucial. If the host site is lined with cortical bone, this must be penetrated with a round bur to open into the underlying marrow, thus allowing progenitor cells and blood vessels to migrate into the area. Wittwer et al., noted that the narrower the distance between the bony walls and from the bone walls to the root, the more predictably the graft will take. [10] Root Debridement Root debridement is a crucial step in grafting procedures. Both ultrasonic and hand instruments are generally used to ensure that all hard and soft deposits and any altered cementum are completely removed from the root surface. Rotary instruments and fiber optic light sources may also enhance debridement. Post-surgical Care Antibiotics are prescribed to suppress plaque accumulation for the first 10 days after surgery or until the patient can adequately control plaque in the area. This is critical for proper wound repair. It is important to emphasize during each recall visit the need for the patient to maintain scrupulous oral hygiene habits including antibacterial rinses. During recall visits, plaque control should be continually monitored, and scaling and prophylaxis are performed as well as occlusion and healing assessment. [18] CONCLUSION The complete analyzes of periodontal regeneration are unpredictable with any regenerative therapy that used in the present with periodontal bone grafts which create a strong capacity. A large body of clinical evidence clearly indicates that grafts consistently lead to better bone fill than non-grafted controls. A study of this is learned mainly of the biologic process of periodontal regeneration with new graft materials are considered to be the task of periodontal regeneration that is even more predictable. The different hard tissue grafts and barrier membranes have been involved for the use of various forms of combinations to elevate the periodontal regeneration. It is quite evident that the mechanical properties, biological behavior, and biodegradation mechanism vary for different graft materials. [19,20] Dental surgeons need to be familiar with the clinical, biomaterials, and biological factors involved in periodontal regeneration. With this case selection, surgical technique, bone graft selection, membrane selection, and post-operative management can be directed toward obtaining the best clinical results; there is no ideal biomaterial option or surgical technique that consistently provides perfect clinical results with regard to periodontal regeneration. Further, extensive research is required with a need to focus on improving the biological interfacing between the graft material and the host tissues. Further, approaches in the field of periodontal regeneration will rely on a combination of therapies with using improved biomaterial options. REFERENCES 1. Ambard AJ, Mueninghoff L. 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