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LECTURER

 

Lecture Topic: BIOMATERIALS FOR IMPLANTATION, CLINICAL APPLICATION IN                          DENTISTRY (PERIODONTAL THERAPY)

Structural biology of the periodontal tissues

Periodontium = A functional system of different tissues, investing and supporting the teeth, including cementum, periodontal ligament, alveolar bone and gingiva.

Periodontal disease

Etiology: plaque

Classification Gingivitis

Periodontitis ---> lost of supporting structures--------> Horizontal bone resorption

                                                                                                       Intrabony defects

                                                                                                                  Furcation involvement

Therapy of Periodontal diseases

Periodontal healing

Repair = healing by scar: formation of long junctional epithelium and arrest bone destruction without necessarily increasing bone height.

Regeneration = healing that results in the formation of a new attachment apparatus, consisting of cementum, periodontal ligament, and alveolar bone.

Osseous grafts and periodontal regeneration

Osteogenesis = the formation and development of bone even in the absence pf local undifferentiated mesenchymal cells.

Osteoinduction = the transformation of undifferentitated mesenchymal cells into osteoblasts or chondroblasts.

Osteoconduction = provides a physical matrix that is bioinert scaffolding suitable for deposition of new bone.

Characteristics of the bone graft materials (Schallhorn 1977)

Biologic acceptability

Predictability

Clinical feasibility

Minimal operative hazards

Minimal postoperative sequelae

Patient acceptance

Types of Bone Graft Materials

Autogenous bone

Allograft

    Fresh frozen bone

     Freeze Dried bone allograft

    Demineralized Bone Matrix

Alloplasts

Ceramic

CaCO3

Bioplant HTR polymer

Bioactive glass

Clinical Application

Intrabony defect

Furcation defect

Ridge Augmentation

Particle Size:

A number of studies have evaluated the effect of particle size on repair and regeneration in bone grafting procedures. There is general agreement that small particles may be preferable from the standpoint of more rapid resorption, greater surface area and enhanced osteogenesis. In the medical, orthopedic, general surgical and oral surgical literature, small usually indicates particles 2mm or greater in diameter. This same dimension would be considered large in the periodontal environment, where small usually means less than 1mm in diameter. The size of the particles is predetermined by the milling process that grinds the bone and then sieves it to select out particles of 100 to 300 um or upto 400 um .

While small particle size may be preferred for periodontal use, particles too small in size may not leave enough interparticular space or large enough pores to allow for the migration and ingrowth of cells, blood vessels and bone. Minimum pore size between particles of greater than 100u m is needed to allow proper vascularization and bone formation. Particle size of about 380u m in diameter would yield this minimal dimension of interparticular space. This principle of interparticular space requirement presumes that the particles are densely packed together and contact each other on all sides.

References:

Mellonig JT, Levy RA. Effect of different particle sizes of freeze-dried bone allograft on the rate of bone growth. J Dent Res 1984;63 (special issue A):461.

Zaner DJ, Yukna RA. Particle size of periodontal bone grafting materials. J Periodontal 1984;55(7):406-409.

Fucini SE, Quintero G, Gher ME et al. Small versus large particle of demeniralized freeze dried bone allografts in human intrabony periodontal defects. J Periodontal 1993;64:844-847.

Becker W, Urist MR, Tucker LM et al. Human demineralized freeze dried bone: inadequate induced bone formation in Athymic mice. A preliminary report. J Periodontal 1995;66:822-828.

Dodson SA, Bernard GW, Kenny EB, Carranza FA. In vitro comparison of aged and young osteogenic and hemopoietic bone marrow stem cells and their derivative colonies. J Periodontal 1996;67:184-196.

Schwartz Z, Mellonig JT, Carnes DL et al. Ability of commercial demineralized freeze dried bone allograft to induce new bone formation. J Periodontal 1996;67:918-926.

Pini Prato GP, Cortelliini P, Aguido G, Clauser C. Human fibrin glue versus sutures in periodontal surgery. J Periodontal 1987;58:426-431.

Pini Prato GP, Cortellini P, Clauser C, Fibrin and fibronectin sealing system in a guided tissue regeneration procedure. A case report. J Periodontal 1988;59:679-683.

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