Biology of Bone Grafting
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Questions and Answers

What is the only non-autogenous material that meets the criteria for an ideal graft material according to the content?

DFDBA

Autogenous grafts are obtained from the same individual and do not elicit any immune reaction or risk of disease transmission.

True

Which of the following are advantages of barriers during wound healing in GTR? (Select all that apply)

  • Promotion of plaque recolonization
  • Exclusion of undesirable cells (correct)
  • Maintenance of space for regenerative cells (correct)
  • Stabilization of the clot (correct)
  • Match the root surface conditioning material with its description:

    <p>Tetracycline = Exposing dentin and cementum collagen, removing endotoxin, collagenase inhibition Citric acid = Removal of endotoxin from root surface, exposing dentin and cementum collagen matrix</p> Signup and view all the answers

    What is the term used to define procedures that aim at regeneration of lost periodontal structures?

    <p>Guided tissue regeneration</p> Signup and view all the answers

    What are some of the growth factors used as adjuncts in periodontal therapy?

    <p>Platelet derived growth factor (PDGF), Insulin like growth factor (IGF), Fibroblast growth factor (FGF)</p> Signup and view all the answers

    What do Insulin Growth Factor I and II stimulate?

    <p>Both a and b</p> Signup and view all the answers

    Fibronectin aids attachment of cells to _______ surface.

    <p>extracellular matrix</p> Signup and view all the answers

    Match the following factors with their roles in bone regeneration:

    <p>Cell Recruitment = Recruitment of osteoprogenitor cells and inflammatory cells to the defect site. Matrix Deposition = Deposition of a blood clot as a scaffold for cell migration and proliferation. Signaling Pathways = Regulation of osteoprogenitor cell differentiation and processes like angiogenesis and bone remodeling.</p> Signup and view all the answers

    Submerged healing protocols for implants placed with bone regeneration decrease bone regeneration complications.

    <p>False</p> Signup and view all the answers

    What type of implant surfaces have been shown to enhance early bone formation and promote a more favorable immune response?

    <p>Hydrophilic, moderately rough</p> Signup and view all the answers

    What is the impact of implant surface characteristics on bone regeneration?

    <p>Implant surface characteristics influence osseointegration and bone formation.</p> Signup and view all the answers

    Hydrophilic surfaces have been shown to elicit a macrophage phenotype associated with increased inflammation.

    <p>False</p> Signup and view all the answers

    Match the following with their impact: Hydroxyapatite-coated implants

    <p>A = Promoted better bone-to-implant contact in regenerated bone B = Enhanced soft tissue complications C = Influence macrophage pro-inflammatory cytokine expression</p> Signup and view all the answers

    Molecular mechanisms mediate through complex signaling pathways to regulate key processes like cell proliferation, osteogenesis, and ______.

    <p>angiogenesis</p> Signup and view all the answers

    What is periodontal regeneration?

    <p>Periodontal regeneration is the reproduction or reconstitution of lost or injured parts so that the form and function of lost structures are restored, including alveolar bone, cementum, and periodontal ligament.</p> Signup and view all the answers

    Horizontal bone loss occurs on a plane that is parallel to a line drawn from the cementoenamel junction (CEJ) of a tooth to that of an adjacent tooth. It is known as _________ bone loss.

    <p>horizontal</p> Signup and view all the answers

    Match the following types of pockets with their descriptions:

    <p>Suprabony pockets = Bottom of the pocket is coronal to the underlying alveolar bone Intrabony pockets = Bottom of the pocket is apical to the level of the adjacent alveolar bone Horizontal bone loss = Bone loss parallel to a line drawn from the cementoenamel junction of a tooth Vertical bone loss = Indicates more rapid bone resorption</p> Signup and view all the answers

    What is the best prognosis for regenerative technique among three wall intrabony defects?

    <p>Three wall defects provide the best prognosis for regenerative technique.</p> Signup and view all the answers

    Which membrane is indicated for vertical dehiscence and defect width reduction?

    <p>Non-resorbable membrane</p> Signup and view all the answers

    Resorbable membranes require a second-stage surgery to be removed.

    <p>True</p> Signup and view all the answers

    What is the drawback of using certain fixation systems with membranes?

    <p>Perforating important anatomical structures</p> Signup and view all the answers

    An ideal membrane should gradually resorb over time while bone forms and matures and its degradation products should not jeopardize the regeneration process. Non-resorbable membranes always require a second-stage surgery in order to be removed.

    <p>collagen</p> Signup and view all the answers

    Match the following bone graft classifications with their origin:

    <p>Autologous grafts = Patient's own bone Allogenic grafts = From a genetically different individual Xenogenic grafts = From a different species Alloplastic grafts = Synthetic material</p> Signup and view all the answers

    What is suggested by pre-clinical studies regarding osteoporosis and bone regeneration?

    <p>Negatively impact on bone regeneration</p> Signup and view all the answers

    What is essential to prevent and manage peri-implant diseases?

    <p>Both a and b</p> Signup and view all the answers

    What factor is associated with a higher risk of peri-implantitis in augmented sites?

    <p>Residual defect height &gt;1mm</p> Signup and view all the answers

    What is the integration of osteogenic cells, bioactive signals, and smart biomaterials aimed at revolutionizing?

    <p>Bone regeneration in implant dentistry</p> Signup and view all the answers

    Is the presence of osteoprogenitor cells important for the success of bone regeneration procedures associated with dental implants?

    <p>True</p> Signup and view all the answers

    What influences the resorption rate and angiogenesis of a grafting material?

    <p>All of the above</p> Signup and view all the answers

    What are the different forms in which allografts are available?

    <p>fresh, fresh frozen, freeze-dried, and demineralized freeze-dried</p> Signup and view all the answers

    Increased levels of ___ porosity promote osteogenesis and faster apposition of new bone.

    <p>microporosity</p> Signup and view all the answers

    Space maintenance is a key factor for successful new bone formation following GBR procedures.

    <p>True</p> Signup and view all the answers

    Match the bone graft material property with its impact:

    1. Macroporosity
    2. Microporosity
    3. Structural interconnectivity

    <p>Macroporosity = Greater degree and faster rate of bone penetration Microporosity = Promotes osteogenesis and faster apposition of new bone Structural interconnectivity = Influences the development of the vascular network essential for new bone formation</p> Signup and view all the answers

    What might delay the osseous formation process in the presence of a biomaterial?

    <p>occupying the space where the newly formed tissue should form</p> Signup and view all the answers

    What factor may negatively impact the bone regeneration process and increase the risk of complications?

    <p>All of the above</p> Signup and view all the answers

    Osteoporosis is considered an absolute contraindication to dental implants.

    <p>False</p> Signup and view all the answers

    Study Notes

    Periodontal Regeneration

    • Definition: The reproduction or reconstitution of lost or injured part so that the form and function of lost structures are restored.
    • Includes regeneration of alveolar bone, cementum, and periodontal ligament.

    Periodontal Repair and Reattachment

    • Periodontal repair: Healing that does not completely restore the architecture or function of the part.
    • Healing by a long junctional epithelium.
    • Reattachment: The reunion of epithelial and connective tissue with a root surface that has been mechanically or surgically separated.
    • New attachment may be epithelial adhesion and/or connective tissue adaptation or attachment.

    Classification of Periodontal Pockets

    • A- 3 wall defect
    • B- 2-wall defect
    • C- combination defect
    • D- 1-wall defect
    • Periodontal pockets can involve one, two, or more tooth surfaces, and can be of different depths and types on different surfaces of the same tooth and on approximal surfaces of the same interdental space.
    • Pockets can also be spiral (i.e., originating on one tooth surface and twisting around the tooth to involve one or more additional surfaces).

    Horizontal and Vertical Bone Loss

    • Horizontal bone loss: When the bone loss occurs on a plane that is parallel to a line drawn from the cementoenamel junction (CEJ) of a tooth to that of an adjacent tooth.
    • Supra bony pockets: When the bottom of the pocket is coronal to the underlying alveolar bone.
    • Intra bony pockets: When the bottom of the pocket is apical to the level of the adjacent alveolar bone.
    • Horizontal bone loss indicates an inflammatory process that has existed over a long period of time.
    • Vertical bone loss indicates more rapid bone resorption.

    Regenerative Techniques

    • Three wall intrabony defects provide the best prognosis for regenerative technique.
    • Availability of regenerative resources is greatly decreased in one wall intrabony defects.
    • Wound healing of a deep narrow three-wall intrabony defect is similar to healing of an extraction socket.
    • Root surface conditioning is essential for formation of new connective tissue attachment.

    Periodontal Regeneration Procedures

    • Grafting procedures
    • Guided tissue regeneration (GTR)
    • Root conditioning and biomodification
    • Biologic mediators for periodontal regeneration (e.g., Emdogain)
    • Combination of any of the previous procedures

    Grafting Materials

    • Osteoinductive: Bone formation is induced in the surrounding soft tissues immediately adjacent to the grafted material.
    • Osteoconductive: The grafted material serves as a scaffold or frame for new bone formation originating from adjacent host bone.
    • Osteoneutral: Serve only as space fillers.
    • Osteogentic: Means that the new bone is formed by bone cells contained in the grafted material itself.

    Classification of Grafts

    • Autogenous grafts: Obtained from the same individual.
    • Allogenic grafts: Obtained from another individual of the same species.
    • Xenogenic grafts: Obtained from another species.
    • Bone substitutes: Bovine derived hydroxyapatite, coralline calcium carbonate, etc.
    • Alloplastic grafts: Bioceramics, polymers, bioactive glasses, etc.

    Selection of Graft Material

    • An ideal graft material should have osteoinductive potential, osteoconductive, accessibility, availability, and safety.

    Guided Tissue Regeneration (GTR)

    • Aims to regenerate lost periodontal structures through selective cell and tissue repopulation of periodontal wound.
    • Uses barriers to exclude undesirable cell types and to create a space for regenerative cells to enter the defect.
    • Indications: Furcations, intra bony defects, gingival recession, alveolar ridge augmentation.
    • Technique: Use of biocompatible and non-resorbable or bioabsorbable barrier membranes, including shaping and placement of the membrane.

    Causes of Failure and Contra-Indications for GTR

    • Causes of failure: Surgical technique, post-surgical factors, barrier dependent factors, and patient-related factors.
    • Contra-indications: Class II furcations on the mesial and distal maxillary molars and premolar furcations, horizontal bone loss, patient's health, compliance, and tooth mobility, and any medication, condition, or disease that may interfere with patient's healing.### Non-Absorbable Barrier Membranes
    • Guidor: a periodontal mesh made of a copolymer of glycolide and lactide, degrades over a period of 3-12 weeks.

    Absorbable Barrier Membranes

    • Atrisorb: a polymer of lactic acid, poly (D, L lactide), dissolved in N-methyl-2-pyrolidone, sets to a firm consistency on contact with water or aqueous solutions, and degrades over a period of up to 3 months.
    • Resolut: a copolymer of PGA and PLA, degrades over a period of 4 weeks to 8 months, with results similar to e-PTFE due to its prolonged resorption time.
    • Epi-Guide: a hydrophilic membrane formed from PLA, contains a flexible open cell structure.

    Root Surface Conditioning Materials

    • Tetracycline: used for root conditioning, acts by exposing the dentin and cementum collagen matrix, removes endotoxin, and has substantivity, collagenase inhibition, and antibacterial effects.
    • Citric acid: used as an adjunct in periodontal therapy, removes endotoxin from root surface, exposes dentin and cementum collagen matrix, and provides anchorage for new fibrin clot and collagen fibrils.

    Biologic Mediators for Periodontal Regeneration

    • Growth factors: stimulate a wide variety of cellular events such as proliferation, chemotaxis, differentiation, and production of extracellular matrix proteins.
      • Platelet-derived growth factor (PDGF)
      • Insulin-like growth factor (IGF)
      • Fibroblast growth factor (FGF)
    • Mediators of bone metabolism: bone morphogenetic proteins (BMPs)
    • Attachment factors: fibronectin
    • Extracellular matrix proteins: enamel matrix proteins (enamel matrix derivative)

    Bone Regeneration in Implant Dentistry

    • Bone regeneration procedures are essential to create an adequate foundation for the placement and long-term success of dental implants.
    • Factors affecting clinical outcomes of bone regeneration in implant dentistry include underlying biology, patient-related considerations, and surgery-related factors.

    The Biology of Bone Regeneration

    • Successful bone regeneration requires the recruitment of osteoprogenitor cells, matrix deposition, and signaling pathways.
    • The deposition of a provisional extracellular matrix provides a scaffold for the migration and proliferation of recruited cells.

    Submerged vs. Non-Submerged Healing

    • Choice of submerged and non-submerged healing protocols can impact the stability and predictability of regenerative outcomes.
    • Submerged healing may increase the risk of contamination of inserted biomaterials due to the inability to attain complete primary closure.

    Surgical Complications

    • Complications such as soft tissue dehiscence, membrane exposure, and infection can negatively impact bone regeneration.
    • Minimizing the impact of such complications is crucial for predictable regenerative outcomes.

    The Impact of Implant Surface Characteristics

    • Implant surface properties, such as topography, wettability, and chemistry, can directly influence osseointegration and bone regeneration.
    • Hydrophilic surfaces can enhance early bone formation and promote a more favorable immune response.

    Impact of Implant Surface on Osseointegration

    • Titanium surface topography and chemistry can influence the proteomic profile released by platelets, which can subsequently influence macrophage pro-inflammatory cytokine expression.
    • Hydrophilic surfaces can elicit a macrophage phenotype associated with reduced inflammation and enhanced pro-osteogenic signaling.### Guided Bone Regeneration
    • Guided bone regeneration is based on the use of an occlusive barrier membrane to create a secluded space around a bone defect
    • The membrane facilitates the recruitment and proliferation of osteoprogenitor cells from the marrow spaces directly into the defect while preventing the downgrowth of neighboring soft tissues

    Properties of Ideal Barrier Membranes

    • Occlusiveness: enables the passage of nutrients, fluids, oxygen, and bioactive substances for cell growth while preventing the passage of unwanted cells
    • Porosity: influences the regenerative outcomes, with moderate porosity allowing the passage of bacteria, cells, and tissue integration/migration
    • Resorption pattern: should gradually resorb over time, with degradation products not jeopardizing the regeneration process

    Stabilization

    • Stabilization of the blood clot and membrane is crucial for bone regeneration to take place
    • Micromovements between bone and implanted material prevent bone formation and result in fibrous tissue development
    • Stabilization methods include fixation screws, non-resorbable pins, or titanium pins, with membrane tucked under the flaps

    Resorption Pattern

    • Resorption rate depends on the physical and chemical properties of the grafting material
    • Autologous bone grafts are incorporated into surrounding bone through "creeping substitution"
    • Allograft incorporation follows a similar sequence of events, but with slower vascular penetration, bone formation, and remodeling

    Bioactivity

    • Membranes not only prevent migration of undesired cells but also promote and direct biological events underpinning bone formation
    • Both resorbable and non-resorbable membranes can host cells that express and secrete pro-osteogenic and bone-promoting factors

    One-Layer vs. Two-Layer Membranes

    • Double-layer membrane technique can enhance the membrane barrier effect and increase the stability of the underlying graft
    • One layer of collagen membrane is often sufficient to promote bone regeneration

    Bone Grafts

    • Bone grafts or substitutes enhance bone healing by bridging small to large defects, preventing membrane collapse, and stabilizing the blood clot
    • Bone augmentation materials are classified according to their origin into autologous grafts, allogenic grafts, xenogenic grafts, or alloplastic grafts

    Properties of Ideal Bone Replacement Grafts

    • Biocompatibility, porosity, osteoinductivity, osteoconductivity, surface properties, biodegradability, mechanical properties, angiogenicity, and ease of handling and manufacturing processes

    Micro- and Macro-Architecture of Grafting Materials

    • Microarchitecture influences the resorption rate and degree of angiogenesis, which can affect volume maintenance over time

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    Description

    This quiz covers the types of bone grafting materials, including autogenous and allogenic grafts, and their characteristics.

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