Ridge Augmentation In Implant Dentistry

Ridge Augmentation In Implant Dentistry

Question. Explain the various types of grafts used in ridge augmentation procedures.
Answer:

• Bone graft materials are generally evaluated based on their osteogenic, osteoinductive, or osteoconductive potential.
• Osteogenesis refers to the formation or development of new bone by cells contained in the graft.
• Osteoinduction is a chemical process by which molecules contained in the graft (bone morphogenic proteins or BMPS) convert the neighboring cells into osteoblasts, which in turn form bone.
• Osteoconduction is a physical effect by which the matrix of the graft forms a scaffold that favors outside cells to penetrate the graft and form new bone.

Read And Learn More: Complete Dentures Question and Answers

Augmentation Procedures Classification of Graft Materials

Augmentation Procedures Based on the Original Source

• Autograft—tissue transferred from one position to another within the same individual.
• Allograft—freeze-dried, fresh: tissue transferred from one individual to another genetically dissimilar individual of the same species.
• Xenograft—tissue transferred from one species to another species, for example, Kielbone (Voxbone).
• Alloplast—a synthetic graft or inert foreign body implanted into tissue.

Augmentation procedures Autogenous Grafts

• Autogenous grafts are harvested from the patient’s own body and are superior at retaining cell viability.
• Contain live osteoblasts and osteoprogenitor stem cells and heal by osteogenesis. No histocompatibility differences and risk of disease transfer. Can be from intraoral and extraoral sites.

Augmentation procedures Bone from Intraoral Sites

Intraoral grafts are osseous coagulum, bone blend, intraoral cancellous bone marrow transplants and bone swaging. The commonest sites intraorally are:

• Edentulous ridges
• Tori
• Maxillary tuberosity
• Healing bony wounds or extraction sites
• Bone trephined from within the jaw without damaging the roots
• The bone was removed during osteoplasty and osteotomy.

1. Osseous Coagulum:
   • Robinson in 1969 described a technique using a mixture of bone dust (from cortical bone) and blood that he termed osseous coagulum.
   • The advantage includes the ease of obtaining bone from already exposed surgical sites, and its disadvantages are its relatively low predictability and inability to procure adequate material for large defects.
2. Bone Blend:
   • Bone is removed from a predetermined site, triturated in the capsule to a workable plastic-like mass, and packed into bony defects.
3. Intraoral Cancellous Bone Marrow Transplants:
   • Cancellous bone can be obtained from the maxillary tuberosity, edentulous areas, and healing sockets. After a ridge incision is made distally from the last molar, bone is removed with a curved and cutting rongeur.
4. Bone swaging:

• • This technique requires the existence of an edentulous area adjacent to the defect from which the bone is pushed into contact with the root surface without fracturing the bone at its base.

Augmentation procedures Bone from Extraoral Sites

• Extraoral site is the iliac crest.
• Iliac Autografts: The use of fresh or preserved iliac cancellous marrow bone has been extensively investigated in bony defects with various numbers of walls, furcations, and even supracrestally.

Augmentation procedures Allografts

• Allografts are bone taken from cortical bone within 12 hours of death, are later defatted, cut in pieces, washed in absolute alcohol, and deep frozen.
• The material may then be demineralized, and subsequently ground and sieved to a particle size of 250 to 750 mm and freeze-dried. Finally, it is vacuum sealed in glass vials.
• The material is then treated with chemical agents or strong acids to effectively inactivate the virus, if still present.

Augmentation procedures There are various types of allografts available, including

1. Freeze-dried bone allograft (FDBA)
2. Demineralized freeze-dried bone allograft (DFDBA).

Augmentation procedures Undecalcified freeze-dried bone allograft (FDBA)

FDBA is an osteoconductive material, whereas decalcified FDBA (DFDBA) is an osteoinductive graft. DFDBA has a higher osteogenic potential than FDBA and is therefore preferred.

Augmentation procedures Decalcified freeze-dried bone allografts (DFDBA)

Demineralization in cold, diluted hydrochloric acid exposes the components of bone matrix that have been termed bone morphogenetic protein.

Augmentation procedures Xenografts

A xenograft is a graft between different species.

Examples of xenografts are:

• Calf bone
• Kiel’s bone
• Inorganic bone
• Natural coral

Augmentation procedures Calf bone: Calf bone (Boplant), treated by detergent extraction, sterilized, and freeze-dried has been used for the treatment of osseous defects.

Augmentation procedures Kiel bone: Kiel’s bone is calf or ox bone denatured with 20% hydrogen peroxide, dried with acetone, and sterilized with ethylene oxide.

Inorganic bone: Anorganic bone is ox bone from which the organic material has been extracted by means of ethylenediamine; it is then sterilized by autoclaving.

Augmentation procedures Two products currently available are:

• Osteo Graf
• Bio-Oss

Natural Coral-Coralline calcium carbonate: Biocoral (Inoteb, France) is a calcium carbonate obtained from a natural coral and is composed primarily of aragonite. It is biocompatible and resorbable with a porous size of 100-200 µm, similar to the porosity of spongy bone.

Augmentation procedures Alloplasts or Nonbone Graft Materials

• Sclera
• Dura
• Cartilage
• Cementum
• Dentin
• Plaster of Paris
• Plastic materials
• Bioceramics – Hydroxylapatite and Tricalcium phosphate
• Bioactive glasses
• Polymers
• Coral-derived materials.

Augmentation procedures Sclera: Sclera was originally used in periodontal procedures because it is a dense fibrous connective tissue with poor vascularity and minimal cellularity hence has a low incidence of antigenicity and other untoward reactions.

Augmentation procedures Cartilage: It can serve as a scaffold.

Plaster of Paris: Plaster of Paris (calcium sulfate) is biocompatible and porous, thereby allowing fluid exchange, which prevents flap necrosis.

Augmentation procedures Plastic materials:

• HTR (Bioplant) polymer is a non-resorbable, microporous, biocompatible composite of polymethylmethacrylate (PMMA) and polyhydroxy ethyl methacrylate (PHEMA), and calcium hydroxide.
• The polymer resorbs slowly and is replaced by bone after approximately 4-5 years. It is oleophilic, and osteoconductive alloplastic bone substitute.

Augmentation procedures Calcium phosphate biomaterials

These materials are osteoconductive. Two types of calcium phosphate ceramics have been used:

1. Hydroxyapatite (HA) has a calcium-to-phosphate ratio of 1.67, similar to that found in bone material. HA is generally nonbioresorbable.
2. Tricalcium phosphate (TCP), with a calcium-to-phosphate ratio of 1.5, is mineralogically B-whitlockite. TCP is at least partially bioresorbable.

Augmentation procedures Bioactive glass

• Consists of phosphates, and silicon dioxide used in the form of irregular particles measuring 90 to 170 µm (PerioGlas) or 300 to 355 µm (BioGran).
• When this material comes into contact with tissue fluids, the surface of the particles becomes coated with hydroxy carbonate apatite, incorporates organic ground proteins, such as chondroitin sulfate and glycosaminoglycans, and attracts osteoblasts that rapidly form bone.

Augmentation procedures Coral-derived materials

• Two different coralline materials have been used in clinical periodontics: natural coral and coral derived- porous hydroxyapatite.
• Both are biocompatible but whereas natural coral hydroxyapatite resorbed slowly (several months), porous hydroxyapatite is not resorbed or takes years to do so.