Ridge preservation & augmentation /cosmetic dentistry course

www.indiandentalacademy.comRidge Preservation & Augmentation

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Part I• Introduction• Keys to bone graftingBone grafting materialsSocket grafting Part IIMaxillary sinus lift & sinus graft surgeryIntraoral autogenous donor bone graftsExtraoral autogenous donor bone grafts

Contents

Introduction

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Absence of infection Soft tissue closure Space maintenance Graft immobilization Regional acceleratory phenomenon (RAP) Host bone vascularization Growth factors BMPs Healing time Defect size & topography Transitional prosthesis

Surgical keys to bone grafting

Rapid solution mediated resorption in conditions of low PH

Absence of infection

Causes of graft material infectionEndogenous bacteriaLack of aseptic surgical techniqueFailure of primary soft tissue closureLack of blood supply in early stages

of grafting

Absence of infection

GuidelinesPrimary incision should be in keratinized

tissue

Soft tissue coverage

Crestal incisionis designed more lingualGuidelines to soft tissue closure

Vertical incisionsGuidelines to soft tissue closure

Vertical incisions are made to the height of MGJ & flap is retracted only 5 mm above the height of MGJ. This maintains more blood supply to the facial flap

Incision is not extended to mobile mucosa

Guidelines to soft tissue closure

Soft tissue reflection distal to graftSite is split thickness

Maintains some of the periosteum around incision line

Early vascularization of incision lineAdhesion of the margins to reduce retraction

during initial healing

Guidelines to soft tissue closure

2 techniques depending on

If less than 5 mm of advancement is necessary

To expand tissue over larger graft sites (15 x 10 mm) -- submucosal space technique

Techniques for soft tissue closure

For a small graft site

More apical tissue reflectionHorizontal scoring of the periosteum parallel

to primary incision

Techniques for soft tissue closure

Developed by Misch in early 1980sFull thickness facial flap is elevated off the

facial bone for 5 mm above the height of vestibule

One incision 1 to 2 mm deep is made through the periosteum parallel to the crestal incision and 3 to 5 mm above the vestibular height of periosteum

Submucosal space technique

Blunt dissection is done using soft tissue scissors (metzenbaum ) to create a tunnel apical to the vestibule & above the unreflected periosteum


Thickness of facial flap should be 3 to 5 mm

Facial flap should be able to pass the lingual flap margin by more than 5 mm


Disadvantages

Loss of vestibular depthLack of keratinized tissue on facial region of

grafted site


Methods

Tent screws

Barrier membrane

Ti reinforced membranes

Graft material beneath the membrane

Space maintenance

Barrier by bulkConcept given by Misch

Methods of space maintenance

MethodsBone tacksTent screwBone screws work better with block bone

grafts than particulate

Graft immobilization / stability or fixation

Fixed transitional prosthesis

Indicated with barrier by bulk tech. using particulate material

Prosthesis should have rest seats & clasps to prevent loading soft tissues

Graft immobilization / stability or fixation

Local response to a noxious stimulus by which tissue forms faster than the normal regional regeneration rate

Healing is 2 to 10 times faster than normal physiologic healing

Begins within a few days after injury , peaks at 1 to 2 months usually lasts 4 months in bone & may take upto 6 to 24 months to subside

Regional acceleratory phenomenon

Decortication to induce RAP

Source of blood vesels Host cortical bone (few

arterioles Cancellous bone

(intensely vascular network

Blood vessels are needed to

Help the autograft maintain vitality

To repopulate the area with osteoblasts

Host bone blood vessels

Host site is decorticated with a rotary drill to

increase amount of host blood vessels at the

graft site

There should be spaces available between

graft particles for blood vessels to enter

Host bone blood vessels

Methods to increase tissue growth factors at graft site-

Use of autologous bone in graftPRPUse of allograftsRAP

Growth factors

Gerald D , Carlson ER , Gotcher JE et al

J of Oral Maxillofacial Surg 2006 : 64 (443 – 451)

PDGF mixed with autologous bone can accelerate mineralization by as much as 40 % during the first year

Growth factors

Factors affecting healing time

LocalNumber of remaining walls of boneAmount of autogenous bone in the

graftSize of the defect

SystemicDiabetes

HyperparathyroidismThyrotoxicosisOsteomalaciaOsteoporosis

Paget’s disease

Healing time

4 to 6 months -- graft volume is less than 5 mm

6 to 10 months -- graft volume is more than 5 mm

Healing time

Defect size effect following aspects of augmentation

Healing time

Vascularization

Transitional prosthesis

Graft material selection

Defect size & topography

Augmentation will be faster in an extraction socket surrounded by 5 walls than for a onlay graft on div D bone

Defect topography

Transitional resto. effectsSoft tissue closureMaintenance of space Immobilization of graft during healingRestores esthetics & functionContours the soft tissue

Transitional prosthesis

Transitional acrylic FPD

Metal reinforced acrylic FPD

Resin bonded prosthesis

Fixed temporary - eg temporaray implants

Removable restoration

Types….

Bone graft materials

Bone graft materials

collagenOsteogenic

Eg autologous bone

Osteoinductive

Eg DFDB

osteoconductive

SourcesBovine collagen from achilles tendon in

the legDFDB

Collagen barrier membranes used for GBR

Resorption rates vary from a few months to 1 year

Collagen

Autogenous trabecular bone

• Contains more osteoblasts• More osteogenic

Autogenous cortical bone

• Contains more bone growth factors• More osteoinductive

Autologous bone

Should remain vital to be able to produce osteoid

Recipient site is prepared first

Should be placed immediately after harvesting or

stored in

Sterile saline

lactated ringers solution

Guidelines for autogenous bone grafting

Should not be mixed with other synthetic graft materials


Decortication of host bone Directly placed on host bone


Phase I OsteogenesisBone regeneration by

surviving cells (osteoid)4 weeks

Phase II OsteoinductionBMP release2 wks to 6 months , peak

at 6 wks

Phase IIIOsteoconductionInorganic matrix

replaced by creeping substitution

Phase IVCortical plate acts as

a barrier membrane

Mechanism of bone growth within autogenous bone graft

The only osteogenic graft material

Osteoinductive property

Osteoconduction

Space maintenance- maintains contour of

desired augmentation

Advantages

Bone autografts

• Frozen bone• Freeze dried bone• Demineralized freeze dried bone

Allograftsosseous transplanted tissues from the same species as the recepient but of different genotype

Osteoinductive materials

Bone can be harvested , frozen & stored to be

used in the same patient at a later date

Allograft frozen bone is rarely used because of

risk of rejection & disease transmission

Frozen bone

Cortical & trabecular bone is harvested in a sterile fashion from a disease free donor

Washed in distilled water & ground to a particle size of 500 micron to 5 mm

Immersed in 100 % ethanol to remove fatFrozen in nitrogenFreeze dried & ground to smaller particle size of 250

to 1500 micron

Freeze dried bone

Marx RE , Wong MEJ of Oral & maxillofacial surg 1987 : 45 ( page

988)

Solvent prserved products have been

developed instead of freeze drying to reduce

antigenicity & assure a minimal risk of

contamination

Freeze dried bone

Ground bone powder is demineralized in 0.6 N

HCl or nitric acid for 6 to 16 hrs.

After acid bath it is washed & dehydrated

DFDB

Irradiation

• Doses greater than 2.5 Mrad are destructive to BMPs

Ethylene oxide sterilization

• 5 hr sterilization at 29 degree celsius to maintain osteoinductive properties

Sterilization

Age of cadaver

Type of bone Cortical bone contains higher conc. Of BMPs than trabecular bone Membranous cortical bone exhibits greater conc. Of BMPs than

endochondral cortical bone

Particle sizeParticles smaller than 150 micron are less effective than 250 micron

or larger

Fibres of cortical bone (eg grafton ) are more effective than particles.

Factors effecting OI property of DFDB

Putty consistency products

Fillers do not participate in bone formation

Recent advances

Allografts

•Freeze dried bone

Alloplasts

•Ceramics•Polymers•composites

Xenografts •Fabricated from inorganic portion of bone from animals other than humans

Osteoconductive materials


Bioinert

•Aluminium oxide•Ti oxide

Bioactive

•Ca Phosphate•Synthetic HA•Bovine derived bone matrix•Tricalcium phosphates•Calcium carbonates

Osteoconductive materials(ceramic alloplasts)

•Non resorbable•resorbable

•Dense•porous

•Crysstalline•amorphous

Osteoconductive materials

Ridge preservation

Atraumatic tooth extraction

Socket grafting

Periosteum should not be reflected if bone

volume is ideal as it helps bone remodellimg

or repair

Soft tissue drape around the tooth is also

affected by reflection of periosteum


An incision within the sulcus is made preferrably with a thin scalpel blade , 360 degree around the tooth


Tooth to be extracted should be reduced mesio distally if the path of removal is obstructed by adjacent teeth


Time period for socket regeneration is usually 3 to 6 months depending on

Tooth sizeRoot no.No. of bony walls around the socketSize of alveolusTrauma of extraction

Socket regeneration

In 1993 Miesch & Dietsh suggested different graft materials & techniques based on the no. of bony walls remaining after tooth is removed-

5 bony wall defect4-5 wall defect2-3 wall defect1 wall defect

Socket grafting

Any resorbable graft material such as alloplast , allograft or autograft

5 bony wall defect

Socket grafting is indicated ifLabial plate of bone is missingOne of the lateral plates is thinner than 1.5

mmHeight is desired

2 techniquesBM with a mineralized alloplast or freeze dried

boneModified socket seal surgery

4 – 5 wall bony socket

A periotome or thin periosteal elevator is used to tunnel under the bone periosteum

BM with alloplast or FDB

barrier membrane is then slid into the pocket created under the tissue & it extends apical , mesial & distal beyond the extraction site

Approx 6-8 mm of BM should extend above the marginal tissue


Bone graft material is placed & BM covers the top of the socket & is tucked in below the palatal tissue


Developed by Misch et al

It’s a composite graft consisting of connective tissue , periosteum & trabecular bone used to seal a fresh extraction socket

J of Oral Implantology 1999 ; 25 (pages 244 – 250 )

Socket seal surgery

AdvantagesCT graft blends into the surrounding attached

gingiva , offering similar colour & texture of the epitheliumcontains autogenous bone

Blood supply is established from the surrounding soft tissue

Rapid healing (4 – 5 months )

Socket seal surgery

• Treated similar to 4 wall defect

Defect size is larger so more bone is reqd.

2 -3 bony wall defect

Block graft or cortical autogenous bone

1 wall bony defect


Misch in 1990, Implant Dent 1993 ;2 (pages 158- 167)

Layers in GBR include the followinghost bone -: decorticated to enhance blood supply , growth

factors & RAPAn autograft-: results in more predictable & rapid bone

growth by osteogenesis & osteoinductionMixture of DFDB (30%) , FDB (70%) , & PRP --: Provides

growth factors & space maintenanceBM & Tent screw -: BM prevents fibroblasts from invading the graft site for at

least 6 wks. Tent screw decreases mobility

Primary closure without tension -: prevents contamination & loss of graft material

GBR : the layered approach


To be continue

d...

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Sinus grafting was introduced by Tatum in 1970s

In early 1970s Tatum began to augment post. Maxilla with autogenous rib bone to produce adequate vertical bone for implant support

In 1974 he developed modified caldwell luc procedure In 1975 he developed a lateral approach surgical

technique toelevate sinus membrane & place implant simultaneously

From 1974 to 1979 primary material for sinus grafting was autologous bone. In 1980 , Tatum introduced the use of synthetic bone

Maxillary sinus graft surgery


Initial publication on sinus grafting was by Boyne & James in 1980s

In 1983 Misch observed that the most predictable intraoral region to grow boneis the max. sinus floor once the mucosa has been elevated

Maxillary sinus graft surgery


Root tips in the antrumPseudocystsOral antral openingExtraction of hopeless teethUnerupted teeth

Conditions of concern to sinus grafting


Narrowing of osteomeatal complexEnlargement of an air cell in the roof of sinus

( haller cell )

SmokingSmokers have a 7 % greater failure rate than non

smokersPt. should refrain from smoking at least 15 days

before surgery & 4-6 weeks after surgery

Chronic maxillary rhinosinusitis

Relative contraindications


Active sinus infection on the day of surgerySignificant recurrent history of chronic

sinusitisSignificant recurrent history of fungal sinusitisUncontrolled late stage diabetesCystic fibrosismaxillary sinus hypoplasiaNeoplasmsInferior turbinate or meatus pneumatization

Absolute local contraindications


Antimicrobial medication Administered at least 1 full day before surgery &

extended for 5 days after surgery

Local antibiotic medications To ensure adequate antibiotic levels in a sinus

graft , it is recommended to add antibiotic to the graft mixture

Mabry TW , Yukna RA J Periodontology 1985 ; 56 (74 – 81)

Premedications


Oral antimicrobial rinse Gentle oral rinses of chlorhexidine gluconate 0.12 %

should be used twice daily for 2 weeks after surgery

Glucocorticoids Initiated 1 day before surgery & continued foe 2

days after surgery to control oedeme

Decongestant medications Oxymetazoline (0.05%) Phenylephrine (1% )

Premedications


Analgesics Codeine containing drugs such as tylenol 3 are

the drug of choice as they have a potent antitussive effect

Cryotherapy Cold dressings for the first 24 – 48 hrs ,elevation

of head & limited activity for 2-3 days helps reduce swelling

After 2-3 days heat may be applied to increase blood flow & lymph flow

Premedications


In 1984 Misch organised a treatment approach for posterior maxilla based upon the amount of bone below the antrum

Treatment classifications for posterior maxilla


in 1995 , Misch modified his classificationto include the lateral dimension of sinus cavity to modify the healing period protocol

Smaller width sinnus (0-10 mm) -: less healing time

Larger width(> 15 mm) -: more time

Treatment classifications for posterior maxilla


SA1 conventional implant placementSA2 sinus lift & simultaneous implant

placementSA3 sinus graft with immediate or delayed

endosteal implant placementSA4 sinus graft healing & extended delay of

implant insertion

Surgical technique


Indicated when sufficient bone height is present for the placement of endosteal implants

Evaluation of sinus is less critical

Implants left to heal for 4-8 months

Progressive loading suggested in d3 & d4 bone

SA1 conventional implant placement


Root form implants are used

At least a 12 mm in height implant for a 4 mm threaded implant

SA1 in Div A bone


Osteoplasty or augmentation is suggested to increase width of bone

Augmentation may be done byBone spreadingAutogenous onlayAppositional grafts

SA1 in div B bone


Onlay autogenous bone grafts are indicated

SA1 in C-w bone


indicated when10-12 mm of vertical bone is presentTatum originally developed the technique in 1970 &

Misch published it in 1987Antral floor is elevated through implant osteotomy

by 0-2mmCompresses the bone below the antrum , causes a

greenstick fracture in the antral floor & slowly elevates the unprepared bone & sinus membrane over the broad based osteotome

Prosthetic treatment similar to SA1 after 4-6 months

SA2 : sinus lift & simultaneous implant placement


SA2 procedure


SA2 procedure


Indicated when at least 5 mm of vertical bone & sufficient width are present between the anral floor & crest of residual ridge

SA3 : sinus graft with immediate or delayed endosteal implant placement


Anesthesia Maxillary branch of trigeminal nerve is blocked Long acting anesthetic such as bupivacaine(0.5%) or

etidocaine(1.5%) is preferred

Incision line & reflection Crest incision is made on the palatal aspect of maxilla from

tuberosity to one tooth anterior to the anterior wall of sinus Vertical relief incision is made on the distal to enhance

access to max. tuberosity Anterior incision is made at least 10 mm ant to the ant wall

of sinus

SA 3 procedure


Access windowTatum access window is 2-5 mm above the

antral floor , 2-5 mm from the anterior wall 15 mm long & 10 mm in height

SA 3 procedure


Carbide bur in paint brush stroke is used to outline the access window

SA 3 procedure


Flat ended metal punch & mallet is used to lightly tap & green stick fracture the access window from the lateral wall of maxilla

SA 3 procedure


Sharp blade of the curette is placed against the inner wall of bone & is used to scrape off the sinus membrane from the bone

SA 3 procedure


Layered approach to grafting

SA 3 procedure


Implant placement

SA 3 procedure


Soft tissue closure

Soft tissues & periosteum must be approximated for closure without tension

SA 3 procedure


Indicated when less than 5 mm bone exists between sinus floor & crest of residual ridge

SA 4 : sinus graft healing & extended delay of implant insertion


Lateral wall approach is performed for sinus graft as in SA 3 procedure

Medial wall of sinus membrane is elevated at least 16 mm fron the crest so that adequate height is available for implant placement

If bone from max tuberosity is not enough , additional bone may be harvested from above the roots of maxillary premolars or mandibular ascending ramus

SA 4 Procedure


Intra operative Membrane perforation Antral septa Bleeding

Short term Incision line opening Paresthesia Acute maxillary rhinosinusitis

Long term Oroantral fistula Maxillary surgical cysts

Complications


Intra oral donor sites


Mandible Symphysis Body Ramus

Maxillary tuberosityExtraosseous toriRidge osteoplastyExtraction sitesImplant osteotomy

Intraoral donor sites


Convenient surgical accessNo cutaneous scarPatients report minimal donor site discomfortInherent biological benefits attributable to the

embryologic origin of donor boneExperimental evidence shows that grafts from

membranous bone show less resorption than endochondral bone. Maxilla & body of mandible are membranous bones

J Oral Maxillofacial surgery 1996 : 54 (15-20)

Advantages of intraoral over extraoral donor sites


Early revascularization of membranous bone grafts helps in improved maintenance of graft volume

Bone from the maxillofacial skeleton contains increased concentration of growth factors & BMPs

Plastic reconstructive surgery 1994 : 93 ( 732 – 738)

Improved survival of craniofacial bone grafts is caused by their 3-D structure

J oral maxillofacial surg 1996 :54 (15 – 20 )

Mand. Cortical bone grafts show little volume loss & show good incorporation at short healing times

Advantages of intraoral over extraoral donor sites


In 1992 Misch et al used mandibular symphysis & ramus bone grafts for endosteal dental implants

J of oral maxillofacial implants 1992 : 7 ( 360 – 366 )

Bone grafts from mandible


Symphysis

Ramus

Donor sites in mandible


Easier graft harvestLess post – op discomfortLess neurosensory complicationsLess incision line openingLess anesthesia reqd.More profound LA with fewer drugsLess concern of changes in facial

morphology

Advantages of ramus as donor site


Less width & length of bone

Disadvantages of ramus as donor site


Slight curved triangular shape in the midlineis often well suited for re-establishing the arch form in maxillary anterior ridges

Average interforaminal distance is greater than 4 cm , so more bone volume is available

Advantages of symphysis as donor site


Width & height requirements for augmentation

Mandibular symphysis : when more than 4 cm of bone is desired ( C-w bone volume )

Mandibular ramus :when graft width is less than 4 mm ( div. B to B-w bone volume )

Mandibular symphysis along with its cortical inferior border : when an augmentation for height is required

Factors affecting mandibular donor site selection


Location of the host or recepient site

Factors affecting mandibular donor site selection

Recepient site

•Anterior mandible•Posterior mandible•maxilla

Donor site•Symphysis•Ramus•ramus


host site prepration

Bone harvest

Graft fixation

Post operative instructions

Grafting procedure


Host site prepration






Bone harvesting


Guidelines for symphysis bone harvest to augment width


Guidelines for symphysis bone harvest to augment height


Presence or absence of molarsWidth & height of external oblique ridge in the

body of the mandibleDistance from the external oblique ridge &

ramus to the inferior alveolar nerveWidth of posterior ramus is evaluated using

reformatted CT image

Guidelines for ramus as a donor site


Guidelines for ramus as a donor site

As a result of these variables a rectangular piece of cortical bone about 3 – 6 mm in thickness may be harvested from the ramus. Length may range from 1 – 3.5 cm & height usually is not greater than 1 cm


After harvesting graft may be stored in sterile saline or immediately fixed to the recepient site

Trabecular surface of the graft should be in contact with decorticated surface of the host bone

Donor block & recepient site contouring2 or more fixation screw sites should be

prepared for each bone block

Graft fixation


Graft fixation

Holes in the donor block should be slightly larger than the outer diameter of fixation screws but smaller in diameter than the head of the screw


A high speed lindemann bur or carbides are then used to recontour the block bone & smmothen any sharp edges or corner after it is fixed

Barrier membrane Not routinely used with cortical block bone grafts Indicated if more particulate or trabecular bone is

used Indicated if block graft is inadequate to fill the

entire space

Graft fixation


Flap should be approximated & sutures placed such that there is no incision line tension or tissue ischemia

Graft fixation


Stop smoking at least 3 days before surgery & until incision line has healed

Removeble soft tissue prosthesis should not be worn

Confirm to regular post operative follow up

Post-op instructions


Intraoral block grafts4 months for maxillary recepient5 – 6 months for mandibular recepient sites

Particulate onlay grafts6 -9 months

Healing time


Iliac crest

Tibia

Cranium

Rib

fibula

Extraoral donor sites


AdvantagesLarge volumeouter portion of the graft may be

primarily cortical with major portion of trabecular bone underneath

Volume of the bone harvested permits contouring of 2/3 of the mandible or maxilla or filling a large bony defect

Relative ease of access & harvesting

Iliac crect cortical & trabecular block grafts


Disadvantages

Rapid bone resorption of 30 – 90 % has been reported when conventional dentures are placed on top of the reconstruction

Curtis et al JPD 1987 ; 57 (73-78)

• post operative pain & gait disturbances



Complications

PainHerniation of the abdominal contentsFracture neuralgiaHematoma seromaInfection cosmetic deformity



Proximal tibial metaphysis provides an excellent source of trabecular bone

Primarily used with with BM & GBR procedure because major part of the harvest is trabecular in nature

Tibial bone grafts


Disadvantages

Contraindicated in adolescents & children coz disruption of epiphyseal growth centre my occur

Fat content of the marrow is sometimes greater than that found in the ilium

Tibial bone grafts


Complications

HematomaPost operative pain Infection Dhiscence ( incidence ranging from 1-4% )

Tibial bone grafts


Sites Iliac crestScapula

indicationsBlood supplybto the graft site is severely compromisedRecipient bed is scarredCarcinoma patients who have undergone radiation

therapyDiv. E bone anatomy : discontinuity defects of the jaw

Vascular bone grafts


Advantages

Maintains normal physiologic functionSimultaneous placement of implants with

microvascular bone flap reconstruction has shown an approximately 80% success rateusing Ti implants with a short follow up



Disadvantages

Attaing primary graft stability is often difficult coz graft is often very spongeous with a thin cortical layer



Refers to the formation of new bone between vascular bone surfaces created by an osteotomy & separated by gradual distraction

IndicationsMucoskeletal conditions such as post

traumatic defectsRepair of continuity defectsMandibular lengtheningMaxillary advancement

Distraction osteogenesis

www.indiandentalacademy.comConclusion


Contemporary implant dentistry by Carl E Misch ; 3 ed

Dental update 1997 ; 24 (332-337)

References


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Ridge preservation & augmentation /cosmetic dentistry course