Bone grafts and periodontalregeneration

MICHAEAL. BRUNSVOLD& JAMES T. MELLONIG

Periodontol 2000 Vol. 1. 2013, 80-91

• Periodontal bone grafting in the past has been controversial and unpredictable

• Strong proponents of bone grafting argue that the majority of healing studies show better success using grafting materials than open flap debridement in managing severe osseous defects.

• Others argue that the amount of bone regeneration possible with current techniques is too limited and unpredictable to be useful

Aim and objective• This review attempts to clarify the role of bone grafting in the

present era of regeneration. • The information discussed includes a definition of terms,

objectives of bone grafting, types of bone grafts, surgical procedure and bone banking

Definition • Periodontal regeneration- Periodontal regeneration is defined

as the process by which the architecture and function of the periodontium is completely restored

• Repair- Defined as re-establishment of continuity without full restoration of architecture and function.

Objectives of bone grafts

• The objectives of periodontal bone grafts are: 1)Probing depth reduction,

• 2) Clinical attachment gain,• 3) Bone fill of the osseous defect and• 4) Regeneration of new bone, cementum and periodontal

ligament

• Animal studies are of value to indicate the potential of graft materials to produce favourable results.

• The results must be viewed with caution, however, and should not be directly applied to humans.

• Animal studies compare graft and non graft procedures in artificially created defects (Table 1).

• The majority of these reports indicate a superior result obtained following the placement of a graft.

• Non graft control sites were never found to be superior to grafted sites

• Human histologic analysis is the gold standard for determining the true potential of any graft material to regenerate the periodontium

• A critical step in these trials is documentation on the root surface of where bacterial contamination occurred prior to treatment.

• Many techniques have been suggested for documentation but the most scientifically valid proof of regeneration of an attachment apparatus is a notch placed in the most apical level of calculus on the root surface (Dragoo MR et al 1983)

Evidence of new bone formation

• Bowers et al. studied this question by comparing the healing of intraosseous defects with and without placement of decalcified freeze-dried bone allografts in human periodontal defects.

• These defects were submerged by complete coverage with soft tissue flaps. • Periodontal regeneration in 30 grafted and 19 non grafted defects was measured

using the most apical level of calculus on the root surface as a reference marker.• Results indicated that regeneration was possible with and without bone grafts in

the submerged environment. • In grafted sites, however, more new attachment apparatus was found than in

nongrafted sites.• Also, the frequency of regeneration was increased in grafted versus non grafted

sites. • Their findings strongly suggest that bone grafts do have an inductive effect on

the periodontium.

• Egelberg et al has stated that there is little indication that bone grafts induce new bone formation or stimulate connective tissue attachment to teeth

Types of bone grafts

• Autografts• Autogenous bone grafts are taken from one part of a patient’s body and

transferred to another. • Several types of autogenous periodontal bone grafts include cortical bone

chips, osseous coagulum, bone blend, extraction socket bone and extraoral cancellous bone with marrow

• The basis for current periodontal bone grafting procedures can be traced to Nabers & O’Leary in 1965.

They used cortical bone shavings removed by hand chisels from within the surgical site.

Using this material, they reported coronal increases in bone• height.• The intraosseous defects so treated were not felt to be amenable to other

forms of treatment.• Long-term documented success of 6 cases was subsequently reported

• Osseous coagulum is obtained by using rotary instruments on intraoral bone in the surgical site and then mixing the particles of bone with the patient’s blood .

• The use of this material is based on the rationale that the small particle size is predictably resorbed and replaced by host bone.

• The mineralized fragments are also thought to induce bone formation.

• Osseous coagulum procedures have disadvantages,• which include aspiration problems, an unknown quantity of

collected bone fragments and limitations concerning the quantity of bone that can be obtained.

• The bone blend technique was designed to overcome some of these problems.

• Bone blend is cortical or cancellous intraoral bone that is obtained with a trephine, chisel or rongeur.

• It is placed in an amalgam capsule and triturated into particle size in the range of 100 to 200 pm

• A mean fill of 73% was reported in a study of 25 defects (Froum SI). In a comparison study, the bone blend grafts produced 2.98 mm in bone fill compared with 0.66 mm when open flap debridement was used (Froum SI)

• Bone from other sources in the oral cavity has been used successfully for periodontal osseous grafts such as maxillary tuberosity, extraction sockets, tori etc. (Soehren SE et al. 1979)

• Autogenous grafts of iliac cancellous bone and marrow offer the greatest potential for induction of new bone in the periodontium (Sottosanti et al. 1975)

Allografts

• Allografts are grafts transferred between genetically dissimilar members of the same species.

• Three types of bone allografts are being used in periodontics.• Demineralized freeze-dried bone is used most often.• Non demineralized freeze-dried bone and • Frozen iliac cancellous bone is used less frequently.• Demineralized freeze-dried bone induces host mesenchymal

cells to differentiate into osteoblasts

• The use of DFDBA in human periodontal defects was first reported by Librin et al. Three sites responded with 4-10 mm of new bone.

• In another study, a mean of 2.4 mm of bone fill was measured in 27 intraosseous defects using cortical DFDBA

• Direct comparison of DFDBA and freeze-dried bone allograft in 11 paired sites showed no statistical difference in probing depth reduction, clinical attachment gain or bone fill (Rummelhardt J et a.1989)

Other factors may influence the choice of using mineralized or demineralized bone.

• Both types of bone are processed with multiple• immersions in absolute ethanol.• Decalcification involves the added immersion in 0.6 N HCI .• Both of these processes are thought to inactivate the human

immunodeficiency virus• In summary, there currently is not an ideal periodontal bone

graft material. All have limitations.

Surgical procedure• The various factors related to the surgical technique of bone

grafting are hard to evaluate scientifically and, therefore, most recommendations are based on clinical observations

• Root debridement is an extremely important step in bone-grafting procedures.

• A combination of ultrasonic and hand instruments is commonly used to insure that all hard and soft deposits plus altered cementum are completely removed from the root surface.

• Surface alterations can als be done to enhance periodontal regeneration.

• These alterations include demineralization with citric acid and tetracycline and the use of attachment proteins and growth factors.

• There is encouraging evidence that at least some of these agents may greatly increase the predictability of bone grafts.

• Guided tissue regeneration using membranes also holds promise for increasing the success of bone grafting.

Conclusion• Periodontal bone grafts have the potential to completely

regenerate the periodontium destroyed by periodontal disease. • Complete regeneration, however,is unpredictable at present• Recent developments related to bone grafting may greatly

enhance their predictability in the future. • These include improved methods for root detoxification, a

better understanding of wound healing, application of the principles of guided tissue regeneration, and use of growth factors