Safety of Bone Allografts Used in Dentistry (2)

8/8/2019 Safety of Bone Allografts Used in Dentistry (2)

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The desire to repair or replace injured ordiseased parts by transplantation of healthytissues has been described in ancient medicalrecords and depicted in works of art many

centuries old.Ollier originally discussed the concept of bone

preservation in 1867.

First concerted effort to store bone for

elective use and description of clinicalefficacy provided by Inclan-1942.

Past decade brought forth significant advancesin bone grafting options.


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Autogenous bone still remains goldstandard of the bone graft materials.

ADVANTAGES:

Use of autografts diminishes risk ofinfectious disease transmission

Osteoconductive, osteoinductive andosteogenic properties of the graft are

optimal.No immune response after implantation,

enhancing its ability to incorporate intoits new site


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DISADVANTAGES:

Harvest of autografts associated with severe donorsite pain and morbidity.

In procedures requiring large amount of graft, there

may not be adequate quantities of autogenous bone

available.

Risk of wound infection

Additional post operative discomfort.


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FDBA DFDBA

FDBA provides an osteoconductive

scaffold and elicits resorption when

implanted in mesenchymal tissues.

DFDBA also provides osteoconductive

surface and in addition, it provides a

source of osteoinductive factors.So, itelicits mesenchymal cell migration,

attachment and osteogenesis when

implanted in well vascularized bone.


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Bone banks exist for the purpose ofsupplying the surgeon with safe andeffective bone tissue that is suitable for

intended clinical application and areavailable whenever the need arises.

Use of substitute for autogenous tissuerequires consideration of its biological

and biomechanical potential as a graftmaterial and of the possibility of transferof disease from ,donor to recipient aswell as the presence and significance ofimmune responses to foreign antigens.


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FDA: FDA Centre for Biologics Evaluation and

Research (CBER) regulates human

cells,tissues and cellular based products

under federal law,title 21 of U.S. Code ofFederal Regulations (cfr),parts 1270 and

1271.

CFR Title 21 part 1271 requires HCT/p

manufactureres to register their companiesand products with FDA cber and comply with

applicable FDA regulations.


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AATB

American Association of Tissue Banks is an

independent nonprofit organization

dedicated to ensuring and maintaining the

safety, consistency and availability ofallografts in the United States.


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Prior to processing, the donors medical/socialhistory is screened for medical conditions or

disease processes that would contraindicate thedonation of tissues in accordance with currentpolicies and procedures approved by BONEBANKALLOGRAFTS.

All BONE BANKALLOGRAFTS policies andprocedures for donor screening, serologic andmicrobiologic testing should meet current

Standards established by the AmericanAssociation of Tissue Banks.


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Donor from high risk groups, as determined

by medical testing and/or behavioral risk

assessments.

Donors testing positive for HIV antibody byELISA

Autopsy of donor reveals occult disease.

Donor bone tests positive for bacterial

contamination.

Donor and bone test positive for Hepatitis B

surface antigen (HBsAg) or Hepatitis C virus

(HCV).


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Donors testing positive for syphilis.

Testing of donor blood and tissue samples

began at the site of recovery and continued

throughout processing.


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NOTIFICATION OFPROSPECTIVE DONORS DEATH

DETERMINATION OF INITIAL DONOR ELIGIBILITY

CONSENT FROM DONOR

DISPATCH OF RECOVERY TEAM

ASSIGNMENT OF TRACKING NUMBER TO

PROSPECTIVE DONOR

DETERMINATION OF ADDITIONAL DONOR

ELIGIBILITY TISSUE PROCUREMENT

AUTOPSY

TRANSPORT


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SOFT TISSUE STRIPPING

INITIAL SIZE REDUCTION

INITIAL CLEANSING AND DECONTAMINATION

MICROBIOLOGICAL TREATMENT

FREEZING

DEHYDRATION

SECONDARY SIZE REDUCTION PACKAGING

TERMINAL STERILIZATION


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SOFT TISSUE STRIPPING

INITIAL SIZE REDUCTION

INITIAL CLEANSING AND DECONTAMINATION

MICROBIOLOGICAL TREATMENT

FREEZING

DEHYDRATION

SECONDARY SIZE REDUCTION

DEMINERALIZATION

BUFFERING FINAL RINSE

PACKAGING

TERMINAL STERILIZATION


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VISUAL INSPECTION TEST

REIDUAL MOISTURE TEST

RESIDUAL CALCIUM TEST


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Exponential reduction in the potential for

graft contamination, disease transfer or

both.

With proper processing, allografts for dentalpurposes routinely achieve SAL of 10-6.

SAL is probability that an item will not be

sterile after it has been subjected to a

validated sterilization process. With a SAL of 106, the odds of an organisms

surviving allograft processing are less than

one in 1 million.


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Most frequently used methods of assuringgraft sterility is irradiation because of the

belief that irradiation will prevent HIV

transmission, thus making it worthwhile to

trade safety for the loss of osteoinductionand alteration of biomechanical properties of

the bone.

However, a study performed by Smith et

al.*shows that, even at doses at which tissuequality begins to be compromised (1.5-2.5

Mrads), irradiation failed to be virucidal for

HIV type 1

* Smith RA, Ingels J, Lochemes JJ, et al: Gamma irradiation of HIV-l. JOrthop Res 19:5, 2001


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Although 4 cases of HIV have been reported

following procedures using frozen bone

allografts, it should be emphasized that

frozen & fresh allografts typically are notused in periodontal therapy.

The delay required to process DFDBA and

FDBA ensures that there is adequate time for

testing for potential pathogens, helping toassure the safety of these materials.


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Mechanical properties of tissues may be

adversely affected by irradiation.

Irradiation of DFDBA reduced bone induction

ability by 40%. Ethylene oxide may produce inflammation

and impair healing, unless it or its by-

products are removed from the graft.


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FDA regulations require human bone

allografts must be tracked so that tissue

banks and clinicians can notify recipients in

the event of a product recall.CFR Title 21 part 1271.290 addresses tracking

protocols for human bone allografts to

facilitate the investigation of actual or

suspected transmission of communicablediseases.


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According to this regulation, HCT/P

processing facilities must label each

manufactured HCT/P

with a uniquealphanumeric identification code that does

not contain the donors name or Social

Security number.

This code allows each manufacturer to record

and track the donor graft to its recipient and

vice versa.

Most tissue banks supply a self-addressed

prepaid postage tracking form with each

human bone allograft


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Ever-increasing use of human bone allografts

reflects positively on the usefulness and

safety of these products.

Progressive FDA policies and industry self-regulation through agencies such as the AATB

have allowed reputable tissue-processing

facilities to uphold their fiduciary

responsibility to the public.


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As is recommended for medical surgeons,

when using human bone allografts in thepractice of dentistry, practitioners should

investigate carefully and be familiar with the

institutions that they are patronizing.

Purchasing products from HCT/Pmanufacturers such as those accredited by

the AATB may provide practitioners with

peace of mind, knowing that these

institutions accept and adhere to strict andreliable safety measures in the creation of

their products.

Safety of Bone Allografts Used in Dentistry (2)

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