INTRODUCTION

Periodontal disease is one of the most prevalent afflictions

worldwide. The most serious consequence is the loss of the

periodontal support structure, which includes cementum, the

periodontal ligament, and alveolar bone.

  Conventional periodontal treatments, such as root planning,

gingival curettage, and scaling, are highly effective at repairing

disease-related defects and halting the progression of

periodontitis. These are important steps; however, the

conventional therapies do relatively little to prompt the

regeneration of lost periodontal support structure.

In fact, studies indicate that they typically result in the

development of a long junctional epithelium between the root

surface and gingival connective tissue rather than the regrowth of

tissue that restores the architecture and function.

Thus, more effective techniques that predictably promote the

body’s natural ability to regenerate its lost periodontal tissues-

particularly alveolar bone – still need to be developed.

Bone grafting is the most common form of regenerative therapy

today and is usually essential for restoring all types of

periodontal supporting tissue.

To date, histologic evidence in humans indicates that bone

grafting is the only treatment that leads to regeneration of bone,

cementum, and a functionally oriented new periodontal ligament

coronal to the base of a previous osseous defect.

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Periodontal regeneration refers to the complete restoration of

functional supporting tissues, including the alveolar bone, the

cementum, and the periodontal ligament.

Regenerative therapy therefore refers to various modalities, such

as bone grafts, root conditioning, and GTR that promote the

body’s natural ability to replace these lost periodontal support

structures.

Periodontal repair refers to the healing of a periodontal wound

with tissue that restores continuity but does not fully restore the

architecture and function of the support structures.

New attachment refers to the reunion of connective tissue with a

root surface that has been deprived of its periodontal ligament.

The new attachment occurs by the formation of new cementum

with inserting collagen fibers.

Reattachment is the reunion of connective tissue with a root

surface n which viable periodontal tissue is present. Nothing new

is formed.

Clinical objectives of bone grafting for periodontal

regeneration

The objectives of bone grafting procedures for patients with

periodontitis are as follows –

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 as determined by histologic analysis.

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In a review of animal histologic studies, Mellonig found that

75% of these studies indicated favorable regenerative results

when periodontal defects were treated with grafting; none

showed that non-graft control sites were superior to grafted ones.

Ideal characteristics of a bone graft are as follows:

Ø Nontoxic

Ø Nonantigenic

Ø Resistant to infection

Ø No root resorption or ankylosis

Ø Strong and resilient

Ø Easily adaptable

Ø Readily and sufficiently available

Ø Minimal surgical procedure

Ø Stimulates new attachmentCurrently, the only reference point

that is considered valid for histologic studies of periodontal

regeneration is a notch placed in the most apical level of calculus

on the root surface.

Based on this scientifically acceptable criterion, new

attachment apparatus has been observed after certain autogenous

and allogeneic grafts.

The objectives of bone grafting are

1.    regenerate a functional attachment apparatus

2.    decrease pocket depth and

3.    establish a healthy maintainable environment.

The possibilities of bone grafting are as follows:

Ø        Actively forms new bone

Ø        Induces bone formation

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Ø        Creates passive surface for bone formation

Ø        Provides mechanical obstruction

Types of graft materials

Several types of bone grafts have been studied over the

years, and periodontists continue to search for ideal materials.

The types of bone grafts are

Ø    Autograft – intraoral and extraoral

Ø    Allograft – freeze-dried, fresh

Ø    Xenogenic – Kielbone (oxbone)

Ø    Alloplastic – synthetic

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 morphogentic proteins or BMPS)

convert the neighboring cells into osteoblasts, which in turn from

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 from new bone.

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Autogenous Grafts

Autogenous grafts, which are harvested from the patient’s

own body, are considered the gold standard among graft

materials because they are superior at retaining cell viability.

These grafts contain live osteoblasts and osteoprogenitor

stem cells and heal by osteogenesis. In addition, autogeneous

grafts avoid the potential problems of histocompatibility

differences and the risk of disease transfer.

AUTOGENOUS BONE GRAFTS :

A. INTRAORAL SITES B. EXTRAORAL SITES

(ILIAC CREST)

1. OSSEOUS COAGULUM

2. BONE BLEND

3. INTRAORAL CANCELLOUS

BONE MARROW TRANSPLANTS

4. BONE SWAGING.

BONE FROM INTRAORAL SITES:

In 1923, Hegedus attempted to use bone grafts for the

reconstruction of bone defects produced by periodontal disease.

The method was revived by Nabers and O’Leary in 1965, and

numerous efforts have been made since that time to define its

indications and technique.

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Autogeneous bone can often be harvested from intraoral sites

including,

Edentulous ridges

Tori

Maxillary tuberosity

Healing bony wound or extraction sites

Bone trephined from within the jaw without damaging the roots

And bone removed during osteoplasty and osteotomy.

Osseous Coagulum

Robinson described a technique using a mixture of bone dust and

blood that he termed osseous coagulum. The technique uses small

particles ground from cortical bone and it provides additional

surface area for the interaction of cellular and vascular elements.

Bone is removed with a carbide but #6 or #8 at speeds between

5000 and 30000 rpm, placed in a sterile dappen dish or amalgam

cloth, and used to fill the defect. The obvious advantage of this

technique is 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.

Bone Blend:

Some disadvantages of osseous coagulum derive from the

inability to use aspiration during accumulation of the coagulum;

another problem is the unknown quantity of the bone fragments

in the collected material. To overcome these problems, the so-

called bone blend technique has been proposed.

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The bone blend technique uses an autoclaved plastic capsule and

pestle. Bone is removed from a predetermined site, triturated in

the capsule to a workable plastic like mass, and packed into bony

defects.

Froum and co-workers have found osseous coagulum – bone

blend procedures to be at least as effective as iliac auto grafts

and open curettage.

Intraoral Cancellous Bone Marrow Transplants

Cancellous bone can be obtained from the maxillary

tuberosity, edentulous areas, and healing sockets. The maxillary

tuberosity frequently contains a good amount of cancellous bone

particularly if the third molars are not present also foci of red

marrow are occasionally observed. After a ridge incision is made

distally from the last molar bone is removed with a curved and

cutting rongeur. Care should be taken not to extend the incision

too far distally to avoid sectioning the tendons of the palatine

muscle also the location of the maxillary sinus has to be analyzed

on the radiograph to avoid cutting into it.

Edentulous ridges can be approached with a flap and

cancellous bone and marrow are removed with curetters. Healing

sockets are allowed to heal for 8 to 12 weeks, and the apical

portion is used as donor material. The particles are reduced to

small pieces.

Bone swaging : this technique requires the existence of an

edentulous area adjacent to the defect from which the bone is

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pushed into contact with the root surface without fracturing the

bone at its base. Bone swaging is technically difficult, and its

usefulness is limited.

BONE FROM EXTRAORAL SITES

Iliac Autografts: The use of fresh or preserved iliac cancellous

marrow bone has been extensively investigated. Data from human

and animal studies support its use, and the technique has proved

successful in bony defects with various numbers of walls, in

furcations, and even supracrestally to some extent

However, owing to problems associated with its use, such as

postoperative infection, exfoliation, sequestration; varying rates

of healing; root resorption; and rapid recurrence of the defect, in

addition to increased patient expense and difficulty in procuring

the donor material, the technique is no longer in use.

Allografts

Allografts are bone taken from one human for

transplantation to another. These grafts, procured from deceased

persons, are typically freeze-dried and treated to prevent disease

transmission and are available from commercial tissue banks.

There are various types of allografts available, including 1.

Freeze-dried bone allograft (FDBA)

2. Demineralized freeze-dried bone allograft (DFDBA).

Both allografts and xenografts are foreign to the organism and

therefore have the potential to provoke an immune response.

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Attempts have been made to suppress the antigenic potential of

allografts and xenografts by radiation, freezing, and chemical

treatment.

Bone allografts are commercially available from tissue banks.

They are obtained from cortical bone within 12 hours of the

death of the 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.

Numerous steps are also taken to eliminate viral Infectivity.

These include exclusion of donors from known high-risk groups

and various tests on the cadaver tissues to exclude individuals

with any type of infection or malignant disease.

The material is then treated with chemical agents or strong acids

to effectively inactivate the virus, if still present. The risk of

human immunodeficiency virus (HIV) infection has been

calculated as 1in 1 to 8 million and is therefore characterized as

highly remote.

UNDECALCIFIED FREEZE-DRIED BONE ALLOGRAFT

(FDBA):

Several clinical studies by Mellonig, Bowers, and co-workers

reported bone fill exceed 50% in 67% of the defects grafted with

FDBA and in 78% of the defects grafted with FDBA plus

autogenous bone.

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FDBA, however, is considered an osteoconductive material,

whereas decalcified FDBA (DFDBA) is considered an

osteoinductive graft. Laboratory studies have found that DFDBA

has a higher osteogenic potential than FDBA and is therefore

preferred.

DECALCIFIED FREEZE-DRIED BONE ALLOGRAFTS

Experiments by urist and co-workers have established the

osteogenic potential of DFDBA. Demineralization in cold,

diluted hydrochloric acid exposes the components of bone

matrix, closely associated with collagen fibrils that have been

termed bone morphogenetic protein.

In 1975, Libin et al reported three patients with 4 to 10 mm

of bone regeneration in periodontal osseous defects studies were

made with cancellous DFDBA and cortical DFDBA. The latter

resulted in more desirable results (2.4 mm versus 1.38 mm bone

fill).

Bowers and associates, in a histologic study in humans, showed

new attachment and periodontal regeneration in defects grafted

with DFDBA.

Mellonig and associates tested DFDBA against autogenous

materials the calvaria of guinea pigs and showed it to have

similar osteogenic potential.

These studies provided strong evidence that DFDBA in

periodontal defects results in significant probing depth reduction,

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attachment level gain, and osseous generation; the combination

of DFDBA and guided tissue regeneration has also proven very

successful.

A bone-inductive protein isolated from the extracellular matrix

of human bones, termed osteogenin has been tested in human

periodontal defects and seems to hence osseous regeneration.’

XENOGRAFTS:

A xenograft is a graft between different spiecies.

2 sources of xenograft are,

Bovine bone &Natural coral

1. Bovine-derived hydroxyapatite

2. Coralline calcium carbonate

3. Calf bone (Boplant)

4. Kiel bone

Bovine Bone:

Commercially available bovine bone is processed to

yield natural bone mineral minus the organic component.

currently available bovine –derived HA is

deproteinated , retaining its natural microporous structure that

support cell mediated resorption. This becomes important if the

product is to be replaced with new bone.

2 products currently available as

Osteograf &

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BioOss

Both have been reported to have good tissue

acceptence with natural osteotrophic properties.

Previously it is available as

Periograf&

Alveolograf

CORROLLINE CALCIUM CARBONATE:

Biocoral is a calcium casrbonate obtained from a

natural coral, genus porites, and is composed primarily of

aragonite. It is biocompatible and resorbable with a porous size

of 100-200um , similar to the porosity of spongy bone .

In contrast to porous HA,derived from the same coral

by heat conversion and non resorbable, calcium corbonate is

resorbable. It does not require a surface transformation in to a

corbonate phase as do other bone substitutes to initiate bone

formation , hence, it should more rapidly initiate bone

formation .

Xenografts:

Calf bone (Boplant), treated by detergent extraction,

sterilized, and freeze dried, has been used for the treatment of

osseous defects.

Kiel bone is calf or ox bone denatured with 20%

hydrogen peroxide dried with acetone, and sterilize with

ethylene oxide.

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Anorganic bone is ox bone from which the organic material

has been extracted by means of ethylenediamine; it is then

sterilized by autoclaving.

Recently, however, Yukna and co-workers used a natural,

anorganic, microporous, bovine-derived hydroxyapatite bone

matrix, in combination with a cell binding polypeptide that is a

synthetic clone of the 15 amino acid sequence of type I collagen.

The addition of the cell binding polypeptide was shown to

enhance the bone regenerative results of the matrix alone in

periodontal defects.

ALLOPLASTS OR NONBONE GRAFT MATERIALS.

In addition to bone graft materials, many nonbone graft materials

have been tried for restoration of the periodontium.

Among them are

Sclera,

Dura,

Cartilage,

Cementum,

Dentin,

Plaster of Paris,

plastic materials,

Bioceramics – HA & TCP

Bioactive glasses

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Polymers

Coral-derived materials.

ALLOPLASTS OR NONBONE GRAFT MATERIALS.

In addition to bone graft materials, many nonbone graft materials

have been tried for restoration of the periodontium.

Among them are

Sclera,

Dura,

Cartilage,

Cementum,

Dentin,

Plaster of Paris,

plastic materials,

Bioceramics – HA & TCP

Bioactive glasses

Polymers Coral-derived materials.

Sclera:

sclera was originally used in periodontal procedures

because it is a dense fibrous connective tissue with poor

vascularity and minimal cellularity. This affords a low incidence

of antigenicity and other untoward reactions. In addition, sclera

may provide a barrier to apical migration of the junctional

epithelium and serve to protect the blood clot during the initial

healing period.

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Although some studies show that sclera is well

accepted by the host and is sometimes invaded by host cells and

capillaries and replaced by dense connective tissue, it does not

appear to induce osteogenesis or cementogenesis. The available

scientific research does not warrant the routine use of sclera in

periodontal therapy.

Cartilage has been used for repair studies in monkeys and

treatment of periodontal defects in humans.’ It can serve as a

scaffolding when so used, new attachment was obtained in 60 of

70 case studies. However, cartilage has received only limited

evaluation.

PLASTER OF PARIS.

Plaster of Paris (calcium sulfate) is biocompatible and

porous, thereby allowing fluid exchange, which prevents flap

necrosis. Plaster of Paris resorbs completely in 1 to 2 weeks, One

study in surgically created three-wall defects in dogs showed

significant regeneration of bone and cementum. It was found be

useful in one uncontrolled clinical study, but other ivestigators

have reported that it does not induce bone ormation.’’ One report

suggested its use in combination with DFDBA and a Gore-Tex

membrane.’ Its use unless in human cases, however, has not been

proven.

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PLASTIC MATERIALS

HTR (Bioplant) polymer is a nonresorbable, microporous,

biocompatible composite of polymethylmethacrylate (PMMA) &

polyhydroxylethylmethacrylate(PHEMA) and calcium hydroxide.

The polymer resorbs slowly and is replaced by bone after

approximately 4-5 years.

A clinical 6-month study showed significant defect fill and

improved attachment level, Histologically, this material is

encapsulated by connective tissue fibers, with no evidence of

new attachment (Stahl et al 1991).

Histologically, new bone growth has been found deposited on

HTR particles. It appears to serve as a scaffold for new bone

formation when in close contact to alveolar bone. Its

hydrophilicity enhances clotting, and its negative particle surface

charge allows it to adhere to bone.

HTR is a clinically beneficial, biocompatible, osteophilic,

and osteoconductive alloplastic bone substitute.

CALCIUM PHOSPHATE BIOMATERIALS.

Several calcium phosphate biomaterials have been

tested since he mid-1970s and are currently available for clinical

se. Calcium phosphate biomaterials have excellent tissue

compatibility and do not elicit any inflammation or foreign body

response. These materials are osteoconductive, not

osteoinductive meaning that they will induce one formation when

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placed next to viable bone but not when surrounded by non—

bone-forming tissue such as skin.

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.

Dense, nonporous, nonresorbable.

Porous, nonresrbable(xenograft)

Resorbable, low temperaturederived

(Bioactive glass, & polymers)

1. When prepared at high temperature (sintered),HA is non

resorbable, non porous &dense & has a larger crystal size.

Dense HA grafts are osteoconductive ,&act primarily as

inert biocompatible fillers.

1. Porous HA is obtained by the hydr45othermal convertion

of the calcium carbonate exoskeleton of the natural coral

genus porites, in to HA .It has a pore size of 190-200um ,

which allows fibrovascular ingrowth & subsequent bone

formation in to the pores & ultimately with in the leision

itself .

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2. Another form of synthetic HA is a resorbable , low

temperature processed , perticulate material . The

resorbable form is is nonsintered with particles measuring

300-400um I t has been proposed that non sintered HA

resorbs acting as a mineral reservoir inducing new bone

formation via osteoconductive mechanism.

Case reports and uncontrolled human studies have shown

that calcium phosphate bioceramic materials are perfectly

tolerated and can result in clinical repair of periodontal lesions.

Several controlled studies were conducted on the use of 1 and

Calcitite clinical results were good, but histologically these

materials appeared to be encapsulated by collagen.

BIOACTIVE GLASS.

Bioactive glass consists of phosphates, and

silicondioxide; & dental applications it is used in the form of

irregular particles measuring 90 to 170 m (PerioGlas, Block Drug

Co., Jersey City, NJ) or 300 to 355 m (BioGran, Ortho Vita,

Malvern, PA). When this material comes into contact with tissue

fluids, the surface of the particles becomes coated with

hydroxycarbonateapatite, Incorporates organic ground proteins

such as chondroitin sulfate and glycosaminoglycans, and attracts

osteoblasts that rapidly form bone.

This material may have potential, and clinical studies are

needed to establish its real usefulness.

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Periglass has a particle size ranging from 90-170um , which

facilitates manageability& packing in to osseous defects.

When compared to TCP,HA &unimplanted controls ,

Fetner et al showed perioglas produced significantly greater

osseous &cementum repair . It also appeared to retard epithelial

down growth , which authors contend may be responsible for its

enhanced cementum &bone repair.

Biogran has a narrower range of particle size of the

purportedly critical 300-355um size range, which has been

reported to be advantageous for guiding osteogenesis. Formation

of hallow calcium phosphate growth chambers occurs with this

particle size because phagocytosing cells can penetrate the outer

silica gel layer by means of small cracks in the calcium

phosphorous layer & partially resorb the gel. This resorbtion

leads to formation of protective pouches where osteoprogenitor

cell can adhere differentiate & proliferate.

CORAL-DERIVED MATERIALS.

Two different coralline materials have been used in

clinical periodontics natural coral & coral derived- porous . Both

are biocompatible but whereas natural coral hydroxyapatiteis

resorbed slowly (several months), porous hydroxyapatite Is not

resorbed or takes years to do so.

  Clinical studies on these materials showed pocket

reduction, attachment gain, and bone level gain. The materials

have also been studied in conjunction with membranes, with

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good results. Both materials have demonstrated microscopic

cementum and bone formation, but their slow restorability or

lack thereof has hindered clinical success in practice.

Grafts in combination with other procedures

During the 1989 World Workshop in Clinical Periodontics,

the consessus was that research should be directed at

combination treatments for periodontal regeneration, involving

bone grafts in conjunction with barrier membranes, root

demineralization and others. Since then, several human studies

have been undertaken, with most involving GTR plus allografts.

Guided Tissue Regeneration

GTR involves the use of a barrier membrane to seal off a

defect site during healing. This barrier, which is sutured in a

tension-free fashion between the defect and thick reflected flaps,

deters undesirable tissues that have no osteogenic potential, such

as epithelium and soft connective tissue, from invading the

wound site during healing. The theory is that this, in turn, allows

space for periodontal ligament cells to grow umimpeded and to

form a new attachment apparatus.

Since its development over the last decade, GTR has been widely

used to treat a variety of periodontal defects successfully. Three-

walled defects respond best to GTR treatment, typically

experiencing substantial bone fill. Other defects that have been

shown to respond well include combination two-walled and

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three-walled defects, funnel shaped defects with definite osseous

stops, and class II furcations with vertical components. When

treating maxillary molars with class II defects, however, only

buccal sites have shown positive responses. Any defect treated

with GTR should be at least 5mm deep.

Root Conditioning

Because the altered root surface can inhibit regeneration

and new attachment, some studies have investigated whether root

conditioning with citric acid or tetracycline to demineralize the

root surface might be a useful adjunct to GTR and grafting

procedures. The theory is that this treatment may expose the

collagen fibrils in the cementum and make the root more

amenable to attachment. This technique is commonly used as part

of other regenerative procedures.

Although animal studies have shown good results, though of

human trials thus far are controversial, particularly pertaining to

tetracycline. Histologic evidence seems to suggest that root

surface demineralization may lead to new connective tissue

attachment and limited regeneration. This conclusion has not

been universal, however, and demineralized root surfaces have

not proven to provide a clinically improved outcome over roots

that were not demineralized.

What to conclude about combination procedures

In reviews of clinical studies investigating combination

periodontal treatment, Schallhorn and McClain and Garrett and

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Bogle noted that the evidence seems to indicate that when both

furcation and intraosseous defects are treated with ePTFE

barriers, adding bone grafts may improve clinical results,

including bone fill and clinical parameters.

Garrett, however, noted that further research is necessary to

evaluate GTR plus bone grafts and to compare the benefits of

each individually in treating intraosseous defects. Few histologic

studies have been done on combined procedures thus far,

however, Stahl and Froum did report evidence of limited

cementogenesis in two of four defects treated with both GTR and

DFDBA and associated osseous remodeling and crestal

osteogenesis. New connective tissue attachment was

histologically detected in two of four calculus notches.

Combined Techniques

The combination of barrier techniques with bone grafts and other

methods has tMlen suggested and proce dures following these

ideas proposed by several au thors. The following technique has

been described by Schalihorn and McClain

1. Perform a regenerative type flap. If recession has occurred

and/or coronal flap positioning is required for membrane

coverage, periosteal__separation is performed.

2. The defect is debrided of all granulation tissue and the root

surface is planed to remove all remnants of plaque, accretions

and other root surface alterations (grooves, notches, caries)

employing ultrasonic! sonic, hand, and/or rotary instrumentation.

3. Odontoplasty and/or osteoplasty are performed if required for

adequate access to the defect including intraradicular or

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furcation hindus concavities and/or reduction of enamel

projections.

The bone graft (typically DFDBA)is prepared in a dap pen dish,

hydrating it with sterile saline or local anesthetic solution, and if

there is no contraindication, is combined with tetracycline (125

mg/O.25 g of DFDBA). After mixing, the dappen dish is covered

with a sterile, moistened gauze to prevent drying of the graft. .

5.The area is thoroughly cleansed and isolated, and the

regenerative site root surface is treated with cot ton pellets

soaked in citric acid pH 1 for 3 minutes, taking care that the

solution does not go beyond the root and bone surface. The

pellets are removed and the site inspected for any residual cotton

fibers prior to flushing the site with sterile water or saline.

6.If a sclerotic bone surface exists in the graft site, intra marrow

penetration is performed with a round but.

7.The ligament surface is “scraped” with a periodontal probe to

remove any eschar and stimulate bleeding.

8. The DFDBA is packed firmly in the defect using an overfill

approach, covering the root trunk and com bination or confluent

vertical dehiscence or horizon tal osseous defects.

9. The custom-fitted membrane is placed over the graft and

secured as appropriate.

10. The area is rechecked to ensure that adequate graft material

remains in the desired area, and the flap Is positioned to cover

the membrane and secured with nonabsorbable sutures.

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11. A periodontal dressing is passively applied over the surgical

area, with Surgical covering the sutures.

Typical pre- and postoperative medication regimens

include, if not contraindicated, 7 to 10 days of antibiotic

coverage, which is subsequently extended with doxycy dine, 100

mg daily for 2 to 7 weeks; steroid therapy such as

methyiprednisolone dosepak; and analgesic agents.

Sutures are removed if and when they become loose or no longer

aid in tissue position or wound closure. The patient is seen for

monitoring and local debridement as needed every 1 to 2 weeks.

If a nonresorbable membrane has been used, it is removed 6 to 8

weeks after the operation.

Several studies and case reports have shown excellent results

with the combined technique.

SUCCESSFUL OUTCOME

Factors adversely affecting outcomes were assessed in the 1996

world Workshop in Periodontics. These included the following:

• inadequate plaque control

• Poor compliance with supportive periodontal therapy

• Smoking

• Other factors such as flap design, defect and root

morphology, material employed, flap position, and post operative

management

Other factors possibly influencing outcomes but which lack

conclusive evidence at this time include: age, systemic

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conditions, and use of membranes irs patients requiring

prophylactic medication.

Other reports have also attempted to delineate variables for

case/site selection and management. These included: therapist

considerations (training and experience), patient factors

(systemic conditions, stress level, smoking habits, plaque

control, patient compliance, tissue response to presurgical

therapy, and age), defect factors (bone height, access,

tooth/defect anatomy, space maintenance of membranes

employed, and tooth stability), surgical considerations (flap

design/management, root preparation and possible

biomodification, regenerative materials employed, infection

control, etc.), postsurgical management, and supportive

periodontal therapy after completion of active therapy.

 

Requirement for a successful graft

Ø      Patient selection

Ø      Material selection

Ø      Proper flap reflection and Wound stability

Ø      Revascularization

Ø      Root debridement

Ø      Post-surgical care

Keys to success in bone grafting

Patient selection – medical/dental Graft placement

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Elimination of all etiologic factors Soft tissue coverage

and

adaptation

Flap design Suturing technique

Root preparation and removal of Appropriate

granulation tissue medication

Postoperative care

GROWTH FACTORS, CYTOKINES& BONE

MORPHOGENETIC PROTIENES:

Investigators are currently studying the potential

therapeutic effects of growth factors & cytokines for

regenaration of alveolar bone. Many of these factors stimulate

regeneration of bone & tissue & influence bone growth &

resorption. Thus may be of benefit in the regeneration process.

Bone morphogenetic proteins are osteoinductive

compounds that induce new bone formation at the site of

implantation ; growth factors & cytokines , in contrast, change

the growth rate of preexisting bone. Studies have shown that

growth factors & BMPs are responsible for normal remodelling ,

healing and repair of bone. Their potential as theraputic

modalities for dentoalveolar reconstruction has been studied.

In an experimentally fractured rabbit mandible , it was

shown that BMP and PDGF are released in to fracture gap

subsequent to the fracture. These findings suggest that these

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substances act as transcription factors to regulate the

proliferation & differntiation of mesenchymal cells .

various annimal studies have been indicated that

recombinant human BMP-2 and PDGFmay have excellent

theraputic potential in ridge augmentation and replacement of

lost alveolar bone .Determination of full potential of BMP will

require further clinical studies.

The early wound healing events of bone were studied

around press-fit titanium implants with and with out the

application of a combination of PDGF and insulin like growth

factors (IGF-1)An increased amount of bone fill was found in the

(PDGF,IGF-1 sites) with prolonged effects seen with larger bone

defects.

Biology of bone healing

Bone heals in a unique way compared with other connective

tissues. Rather than developing scar tissue, it has the ability to

regenerate itself completely. In fact, bone is constantly being

resorbed and remodeled – a delicate balance coordinated by a

rather complex cascade of cellular events that researches are still

working to dissect.

The bone repair process begins with an inflammatory

response that prompts granulation tissue to profilerate in the

wound site. This granulation tissue brings in capillaries,

fibroblasts, and osteoprogenitor cells.

Osteoblasts, which are the bone-producing cells, are

produced by the osteoprogenitor cells in the granulation tissue,

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and they begin to make the organic matrix of woven bone and to

initiate mineralization. This healing mass of new tissue is called

the callus, and it is an architecturally disorganized mass.

Over time, this woven bone is replaced by lamellar bone as bone

remodeling units invade the healing area. As this replacement is

proceeding, the new bone growth is also being modeled to form

an organized structure.

  Osteogenesis, or the process of bone formation, begins with

either osteoblasts in the patient’s natural bone or from the

surviving cells in the bone graft that is placed. Through a gradual

healing process that begins with inflammation, bone grafts are

incorporated into the patient’s natural oral bone structure over

time. The process of bone formation in relation to various types

of grafts is discussed later.

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