Year : 2015 | Volume
: 5 | Issue : 2 | Page : 97--104
An ounce of prevention is worth a pound of cure: A review on ridge augmentation
Nandini Manjunath, MR Arjun
Department of Periodontics, A. J. Institute of Dental Sciences, Mangalore, Karnataka, India
M R Arjun
Department of Periodontics, A. J. Institute of Dental Sciences, Mangalore, Karnataka
A deformed alveolar ridge may result from periodontal disease, trauma, tooth extraction, tumor, or congenital defects. The ridge deformity is directly related with the volume of the root structure and associated bone that is missing or has been destroyed. The esthetic, hygiene, and functional concerns can be the formation of “black triangles” interdentally, loss of buccal/facial contour, an unesthetic thick pontic made to compensate the horizontal ridge defect, food impaction in the open interdental spaces under the pontic, difficulty in speech and unesthetic gingival texture. In today's practice, patients with normal skeletal pattern who have lost a substantial degree of their original osseous dimensions due to tooth loss or trauma are much more prevalent. Alveolar ridge defects are common and poise a significant problem in dental treatment and rehabilitation. A thorough knowledge of ridge augmentation is required for successful interdisciplinary approaches. Therefore, the time-honored proverb that “an ounce of prevention is worth a pound of cure” is most applicable to the many problems involved in the successful reconstruction of localized defects that exist within the alveolar ridge. The following databases were searched to collect all relevant articles in relation to ridge augmentation procedures “PubMed” and “Medline” using the following descriptors–ridge augmentation, ridge preservation, allografts, autografts, block bone grafts, interdisciplinary approach, and the data was accumulated and analyzed. All the articles available from 1920 to December 2014 were included for review analysis. A total number of 520 articles were collected out of which most relevant ones were included in this article.
CLINICAL RELEVANCE TO INTERDISCIPLINARY DENTISTRY
Dental professionals have the opportunity to make their patients aware of these new treatment modalities in regard to ridge preservation and augmentation. Recent findings and scientific research articles support the use of ridge augmentation for better esthetics. A future development of the application of ridge augmentation in interdisciplinary dentistry requires a comprehensive joint program to provide the patient with the best available treatment in this field.
|How to cite this article:|
Manjunath N, Arjun M R. An ounce of prevention is worth a pound of cure: A review on ridge augmentation.J Interdiscip Dentistry 2015;5:97-104
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Manjunath N, Arjun M R. An ounce of prevention is worth a pound of cure: A review on ridge augmentation. J Interdiscip Dentistry [serial online] 2015 [cited 2021 Apr 17 ];5:97-104
Available from: https://www.jidonline.com/text.asp?2015/5/2/97/173228
A deformed alveolar ridge may result from periodontal disease, trauma, tooth extraction, tumor, or congenital defects. The ridge deformity is directly related with the volume of the root structure and associated bone that is missing or has been destroyed. The esthetic, hygiene, and functional concerns can be the formation of “black triangles ” interdentally, loss of buccal/facial contour, an unesthetic thick pontic made to compensate the horizontal ridge defect, food impaction in the open interdental spaces under the pontic, difficulty in speech and unesthetic gingival texture. There are high incidences of residual ridge deformity following anterior tooth loss, a majority of these are class three defects. This article reviews all the available aspects of ridge augmentation.
History of Ridge Augmentation
The use of bone grafts in can be traced to the work of Hegedus. He reported success in six cases by transplanting autogenous bone from the tibia to the jaws to treat “advanced pyorrhea. ” Subsequent to this report and for the next several decades, the evaluation of xenografts of various types became the main focus of attention. Beube and Silvers  used boiled cow bone powder to successfully repair intrabony defects in humans. Studies in dogs suggested that surgically created periodontal defects had an accelerated rate of healing after placement of boiled cow bone powder, with bone and cementum being deposited more rapidly in grafted defects.,
Etiology for ridge defects
The loss of teeth and alveolar structures can result from many causes:
Improper tooth extractions,Advanced periodontal disease,Abscess formations,Tumor,Trauma,Congenital disease,Implant failures, andLong standing periapical infections.
Ridge Augmentation Using Hard Tissue
Resorption of alveolar bone is a common sequela of tooth loss and presents a clinical problem, especially in the esthetic zone. This may jeopardize the esthetic outcome and compromise the functional and structural aspects of treatment. To achieve this goal of therapy, it is desirable to provide treatment that will aim at augmentation of deformed alveolar ridge proposed for implant prosthesis. This has necessitated development of techniques and materials that promote the predictable regenerative treatment. Regeneration refers to the reconstitution of a lost or injured part by complete restoration of its architecture and function.
Ideal characteristics of a bone graft are:,
Nontoxic,Nonantigenic,Resistant to infection,Do not cause root resorption or ankylosis,Strong and resilient,Easily adaptable,Ready and sufficiently available,Minimal surgical procedure,Stimulate new attachment, andBe able to trigger osteogenesis, cementogenesis, and formation of a functional periodontal ligament.,
Bone graft materials are evaluated based on their osteogenic, osteoinductive, or osteoconductive potential. Osteogenesis refers to the formation of or development of new bone by cells contained in the graft. Osteoinduction is a process or a set of processes that stimulate the phenotypic conversion of progenitor cells within the healing wound to those that can form osseous tissue.
Osteoconduction defines the process that permits osteogenesis when cells already committed to bone formation are present in a closed environment.
These grafts can again be
Autografts: Tissue transferred from one position to another within the same individualAllografts: Tissue transferred from an individual to another genetically dissimilar individual of the same speciesXenografts: Tissue transferred from one species to another speciesAlloplast: A synthetic graft or inert foreign body implanted into tissue.
Autogenous bone graft, which is harvested from the patient's body, is considered ideal because of its osteoconductive and osteoinductive properties and because it contains a source of osteoprogenitor cells. It is still considered the gold standard by which other grafting materials are compared.
Intraoral autogenous bone grafts harvested from the maxillary tuberosity, edentulous alveolar areas, healing bone wound, extraction sites, and mental and retromolar areas., Several types of autogenous bone grafts can be used:
Cortical bone chips: These are not used today because they are generally much longer particles 1559.6 mm x 183 mm and have a higher potential for sequestration Osseous coagulum: This is made by harvesting intraoral bone with round burns, and then mixing it with blood. Early studies in monkeys showed that small particle size (100 mm) led to earlier and higher osteogenic activity than did the larger particles. The disadvantages in using the osseous coagulum are the uncertain quality of the collected bone fragments and the material's fluidity Blend of cortical and cancellous intraoral bone: Bone blend is the combination of cortical and cancellous bone that is procured with a trephine or rongeurs, placed in an amalgam capsule, and triturated to the consistency of a slushy osseous mass. The final particle size is about 210 mm x 105 mm.
Extraoral autografts from iliac cancellous bone and marrow provide a great osteogenic potential, being able to induce cementogenesis, bone regeneration, and Sharpey's fibers reattachment.
The allografts are obtained from other individuals of the same species but disparate genotype. They include:
(a) Freeze-dried bone allografts (FDBAs) and (b) demineralized freeze-dried bone allograft (DFDBA). Bone allograft is the most frequently used alternative to autogenous bone for bone grafting procedures in the USA. The two types of allografts work by different mechanisms. FDBA provides an osteoconductive scaffold and elicits resorption when implanted in mesenchymal tissues. DFDBA also provides an osteoconductive surface. In addition, it provides a source of osteoinductive factors. Therefore, it elicits mesenchymal cell migration, attachment, and osteogenesis when implanted in well-vascularized bone, and it induces endochondral bone formation when implanted in tissues that would otherwise not form bone.
Xenografts are grafts shared between different species. Currently, there are two available sources of xenografts used as bone replacement grafts in periodontics: Bovine bone and natural coral. Xenografts are osteoconductive, readily available, and risk-free of disease transmission. The latter point has been questioned with the discovery of bovine spongiform encephalopathy, particularly in Great Britain.
Anorganic bovine-derived bone xenograft
The bovine-derived bone xenograft (BDX) is a xenograft consisting of deproteinized, sterilized bovine bone with 75–80% porosity, and a crystal size of approximately 10 mm in the form of cortical granules. Regarding both the chemical and physical features, BDX is considered identical to the human bone.
Coralline calcium carbonate
Natural coral graft substitutes are derived from the exoskeleton of marine madreporic corals. The structure of the commonly used coral Porites is similar to that of cancellous bone, and its initial mechanical properties resemble those of bone. The mineral composition of bone is mainly hydroxyapatite (HA) and amorphous calcium phosphate associated with calcium carbonate while coral is essentially calcium carbonate.,
An alloplast is a biocompatible, inorganic synthetic bone grafting material. At present, alloplasts marketed for periodontal regeneration fall into two broad classes: Ceramics and polymers. They are osteoconductive only. They eliminate the risk of disease transfer and procurement morbidity, and it is abundantly available.
Slowly resorbing ceramics (calcitite)
HA exhibits brittleness and resorbs slowly. According to a study by Taylor et al., synthetic HA materials allowed osteoclast attachment but exhibited limited surface etching, which is consistent with limited osteoclast resorptive activity.
Ultraporous beta-tricalcium phosphate (e.g., orthograft)
A highly porous bone void filler that is composed of 90% interconnected void space with a broad range of pore sizes that is similar to the natural trabecular pattern of cancellous bone. The material can be manipulated during placement, sculpted as blocks, or packed. After it is packed to conform to the shape of the bone defect, its high porosity remains intact. The resorption rate of beta-tricalcium phosphate (b-TCP) scaffold is intended to match the course of natural bone healing after implantation.
It is actually Plaster of Paris. It is a safe, biocompatible, osteoconductive bone graft substitute that acts well as space filler preventing the ingrowth of soft tissue allowing osseous ingrowth in bone defects. Calcium sulfate in its set form has a compressive strength greater than cancellous bone and a tensile strength slightly less than cancellous bone. For this reason, it has no reliable mechanical properties in vivo. The primary use of calcium sulfate is like a bone void filler.
Bioglass are particulate materials, slowly resorbing and when mixed with fluids form an adherent surface layer of silicon, calcium, fluoride, and sodium, which binds the graft to the bone. They are not osteoinductive but conduct bone mineralization by promoting absorption and concentration of proteins used by osteoblasts to form the extracellular matrix of bone.
In addition to its osteoconductive properties, it also has an osteostimulatory effect showing bone growth within eroded particles.
Biocompatible oteoconductive polymers (e.g., hard tissue replacement)
It is a nonresorbable, particulate of calcium layered with polymethylmethacrylate, and polyhydroxyethylmethacrylate. The hard tissue replacement is reported to act as its own barrier and prevent gingival soft tissue migration ingrowth. Histologically, it is osteoconductive and biocompatible and can be used both as bone substitute and as a barrier for guided tissue regeneration in implant therapy. No complications caused by infection, inflammation, or rejection of the implanted graft material were observed in a study done by Haris et al. in 224 patients over a period of 5 years. A thorough knowledge of these grafts is required for successful interdisciplinary approaches.
One of the most promising emerging surgical options may be the use of a “composite graft ” that contains osteogenic cells and osteoinductive growth
factors along with a synthetic osteoconductive matrix. When an osteoconductive scaffold is seeded with bone morphogenetic proteins (BMPs), for example, the composite graft may become both osteogenic and osteoinductive, providing a competitive alternative to autograft., Such potential composite grafts are bone marrow/synthetic composites, ultraporous b-TCP/bone marrow aspirate (BMA) composite, osteoinductive growth factors and synthetic composites, BMP/polyglycolic acid polymer composites, and BMA/BMP/polyglycolic acid polymer composite.
Block bone graft
The idea of increasing the available bone volume by means of auto, allo, and xenografts has been tested since the beginning of the 20th century. The morphology of a bony defect is an important consideration in the selection of a method of ridge augmentation. Allografts and guided bone regeneration techniques are used for bone repair; these methods produce less favorable results in the treatment of larger bone defects., The use of particulate autogenous bone in combination with barrier membranes has been extensively reported to be effective when small edentulous segments such as single tooth deficiencies are to be treated.
Autogenous bone block
The use of autogenous bone grafts represents the gold standard for bone augmentation procedures. Autogenous bone grafts may act mostly as scaffolds and are thus more osteoconductive than osteoinductive even though osteogenic activity may have remained in the spongious part of the graft. Autogenous bone grafts are either cortical blocks, corticocancellous blocks, bone chips, or compressed cancellous bone cakes. A recent study on 115 autogenous block grafts reported only one complete failure, where the block graft was removed.
Autogenous intraoral bone block
Autogenous bone graft can be harvested from extraoral donor sites. Several studies have confirmed that intraorally harvested intramembraneous bone grafts when compared with extraoral harvested endochondral bone grafts may have minimal resorption.,
Bone block from symphysis
Larger bone volume could be harvested from the symphysis compared with other intraoral sites. The amount of bone required at the prospective implant site often dictates the donor site so to augment the anterior maxilla; the mandibular symphysis has been reported to provide adequate volume.
Bone block from ramus site
The mandibular ramus area is another donor site that can be considered in ridge augmentation for implant placement. The technique for bone harvest has many features similar to the sagittal split ramus osteotomy for jaw repositioning. These grafts require a short healing period and exhibit minimal resorption while maintaining their dense quality.
Bone block from other intraoral sites
Other intraoral sites so far used for this purpose include retromolar area, zygomatic buttress, maxillary tuberosity, and mandibular tori. The zygomatic buttress has a strong bony pillar that provides pressure absorption and transduction in the facial skeleton. Ideally, the patient should have a negative history of any sinus problems. As an additional caution, use of ultrasound-based dissection with piezosurgery further reduces the danger of perforating the sinus membrane.
Autogenous extraoral bone block
Although excellent clinical and histologic outcomes have been reported with intraoral bone blocks, several types of alveolar ridge defects cannot be repaired because of unavailability of sufficient quantity of bone. Therefore, in cases where large amounts of bone are required, extraoral sources of autogenous bone have been considered. Extraoral sources for bone block include the iliac crest, tibia, skull, or calvarium. The onlay/inlay bone grafting techniques have been used in situ ations with a normal or acceptable maxillomandibular relationship.
Allogenic bone blocks
Currently, the gold standard for bone reconstruction is the use of autogenous bone. However, major drawbacks are limited sizes of the grafts available, donor site morbidity, the need for general anesthesia, immediate postoperative pain and edema, neurological disturbances, vascular complications, infection, scars, and organ deformity. Other drawbacks are insufficient initial bone density of the restored area and inability to sustain functional load, which results in graft resorption over the long term  Allograft has advantages, such as easy manipulation, great amount of material available, cost reduction, morbidity reduction, and elimination of additional donor site. Therefore, recently various types of allografts have been used for ridge augmentation procedures.
Distraction osteogenesis technique
Osteogenic distraction is defined as the creation of new formed bone and adjacent soft tissue after the gradual and controlled displacement of a bone fragment obtained by surgical osteotomy. Distraction of the segment can be achieved in a vertical and/or a horizontal direction. The basic principle developed by Illizarov , has the following three distinct phases:
A latency phase of approximately 7 days of initial postsurgical healing;the distraction phase, consisting of the gradual, incremental separation of two bone pieces at a rate of approximately 1 mm/day;consolidation phase, during which new bone forms in the regenerate zone between the separated bone pieces.
Ridge split technique
Expansion of the existing residual ridge of the atrophic maxilla and mandible for implant insertion and augmentation has been referred to as ridge splitting, bone spreading, ridge expansion, or the osteotome technique. After tooth loss, the thin buccal cortex of the maxillary alveolus resorbs to a greater degree than the thicker palatal socket wall. This resorption results in a decrease in bone width and a more medial position of the residual ridge., The narrower ridge in the anterior maxilla and premolar areas is often inadequate for placement of standard-diameter dental implants (4.0 mm). In such situations, ridge split technique has been advocated to expand the ridge to allow placement of an appropriate size implant for proper prosthetic contour and biomechanical support. Ridge splitting for root-form implant placement was developed in the 1970s by Dr. Hilt Tatum  Tatum developed specific instruments including tapered channel formers and D-shaped osteotomes to expand the resorbed residual ridge. Summers  later revived the interest in this technique; he developed round implant osteotomes suitable for use with commercially available cylinder root-form implant systems.
Ridge Augmentation Using Soft Tissue
Use of soft tissue graft
Localized deformities in the partially edentulous ridge may be reconstructed by using one or combination of different concepts in the treatment. Soft tissue graft that employ de-epithelized connective tissue, subepithelial connective tissue or interposition connective tissue graft can be used to reconstruct the tissue over the ridge defect. A second method is to use free grafts of masticatory mucosa (onlay grafts of varying thickness) to build up the thickness of soft tissue overlying a deformity. A thorough knowledge of soft tissue grafting is required for successful interdisciplinary approaches.
The de-epithelized connective tissue pedicle graft or “roll procedure ”
The basic concept of the procedure involves the creation of a connective tissue pedicle that is placed or tucked into a subepithelial pouch. The de-epithelized connective tissue pedicle graft or roll procedure ” was developed by Abrams. This procedure was the first of the periodontal surgical procedures that have been developed to augment ridge deformities. Abrams's initial work provided the stimulus to others to seek new methods to treat ridge deformities rather than accept traditional prosthetic solutions to these problems.
Modified roll technique
Scharf and Tarnow  described a modification of Abram's roll technique, a “trap-door ” approach was used to reflect and preserve the epithelium that overlies the connective tissue pedicle; the epithelial pedicle is used to cover the donor site. The first step was to define and reflect the epithelial pedicle. Two full thickness vertical releasing incisions were made from the crest of the ridge toward the palate. These incisions should be roughly parallel to each other to maximize the blood supply to both the epithelial and connective tissue pedicles. The length of the incisions was dependent on the length of connective tissue needed.
Pouch procedures for subepithelial grafts
There are three varieties of pouch procedures that have been designed to receive free grafts of connective tissue removed from the palate or implants of bone or synthetic bone substitutes. They vary only in the direction in which the entrance incision and plane of dissection is made. A subepithelial pouch is created in the same manner as previously described for the de-epithelized connective tissue pedicle graft procedure. Instead of rolling a pedicle of connective tissue into the pouch, a free graft of connective tissue that is taken from the palate, autogenous bone chips or allograft bone material, or synthetic bone material, such as hydroxylapatite, is placed into the pouch. The graft or implant material is placed and molded to create the desired contour in the ridge, and the entrance incision is closed with sutures.
Interpositional (wedge and inlay) graft procedures
These procedures differ slightly from the pouch procedures in which a subepithelial (subconnective tissue) graft or implant is used. The opening of the pouch is not closed in this type of procedure. A pie-shaped free graft is removed from the palate, tuberosity area, or edentulous ridge and is inserted like a wedge into the opening of the pouch., The labial surface of the pouch is elevated buccally in an amount necessary to eliminate the concavity in the ridge. The wedge-shaped graft is then placed into the space provided to maintain the labial surface of the pouch in the desired position. The epithelial surface of the wedge is positioned at the level of the surrounding epithelial surfaces, and the wedge is maintained in this position by sutures. If augmentation is required in an apicocoronal dimension as well as buccolingually, part of the wedge is positioned above the level of the surrounding tissues.,
Onlay graft procedures
The onlay procedure was designed to augment ridge defects in the apicocoronal plane, i.e., to gain ridge height., Onlay grafts are epithelialized free grafts which, following placement, receive their nutrition from the de-epithelialized connective tissue of the recipient site. The amount of apicocoronal augmentation that can be obtained is related to the initial thickness of the graft, the events of the wound healing process and the amount of graft tissue that survives.
Tissue engineering approach for ridge augmentation
The molecular approach using BMPs has received the most attention over the past decade. BMPs are differentiation factors that are part of the transforming growth factor superfamily. They have multiple effects, including the ability to differentiate osteoprogenitor cells into mineral-forming osteoblasts. Two of these proteins, BMP-2 and -7 (or osteogenic protein-1),
have been cloned, studied extensively, and show promise for intraoral applications., Human studies , demonstrated product safety with BMP-2 in ridge preservation and sinus augmentation applications. Although a large number of growth factors is being evaluated actively, platelet-derived growth factor has received the most attention for intraoral use. Gene therapy is a relatively new therapeutic modality based on the potential for delivery of altered genetic material to the cell. Localized gene therapy has been tried to increase the concentration of desired growth or differentiation factors to enhance the regenerative response. With the current requirement for supraphysiologic BMP doses to obtain acceptable clinical results, this approach to deliver higher concentrations to the local bone augmentation site over longer periods of time showed promising results.,
In today's practice, patients with normal skeletal pattern who have lost a substantial degree of their original osseous dimensions due to tooth loss or trauma are much more prevalent. Alveolar ridge defects are common and poise a significant problem in dental treatment and rehabilitation. Therefore, the time-honored proverb that “an ounce of prevention is worth a pound of cure ” is most applicable to the many problems involved in the successful reconstruction of localized defects that exist within the alveolar ridge. This objective can be achieved if teeth are extracted in an atraumatic manner and appropriate implant materials are placed into the sockets to prevent the eventual collapse of the ridge. Guided tissue regeneration procedures also may be used to prevent collapse within the ridge or augment an existing defect.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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