onlay bone graft

1. Onlay bone graft
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Dr. Mushahida Anjum
Dental College Azamgarh
Guided By
Dr. Deepak Chopra

2. CONTENTS
 Introduction
 Definition
 Classification
 Sources
 Types
 Structure
 Indication
 Surgical protocol
 Complication
 Bone Healing
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3. INTRODUCTION
 The primary goal of periodontal treatment is the
maintenance of the natural dentition in health and
comfortable function.
 When periodontal disease has caused a loss of the
attachment apparatus, optimal care seeks to regenerate
the periodontium to its pre-disease state.
 Regeneration is natural renewal of structure, produced by
growth & differentiation of new cells & intercellular
substances to form new tissues or parts.
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4. Different surgical methods have been proposed to treat
bone deficiency
 Guided bone regeneration technique
 Bone graft
 Distraction osteogenesis
Among these surgical procedures, bone reconstruction
with onlay bone graft is most versatile as it can be used
to treat the vast majority of defects irrespective of
variables such as type of atrophy and extent of the defect,
and clinical results are favorable and stable in time either
for the reconstructed bone and for implants placed in the
reconstructed areas, with implant survival rates ranging
from 90 to 100% for rough surface implants
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5. WHAT IS GRAFT ??
A viable tissue that after removal from a donor site is
transplanted with in a recipient tissue is then restored
repaired & regenerated.
Procedure used to replace / restore missing bone or gum
tissue is called grafting.
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6. DEFINITION
Onlay graft is a bone graft in which transplanted tissue is
laid directly onto surface of recipient bone
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7. CLASSIFICATION
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Human
bone
Vascularized
Revascularized
Non
vascularized
Bone
substitute
Xenograft
Alloplast
Bone graft

8. HUMAN BONE
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Extraoral
Intraoral
Autograft
Fresh frozen
bone
Freeze dried
bone allograft
Demineralized
freeze dried
bone allograft
Allograft

9. BONE SUBSTITUTE
Xenograft
Bovine-derived
hydroxyapatite
Coralline
calcium
carbonate
Alloplast
Polymers
Bioceramics
Bioactive
glasses
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10. SOURCES
 Extra oral
e.g. proximal & distal tibia, fibula, ilium, calvaria, distal
condyle & greater trochanter of femur, olecranon process
of ulna, styloid process of radius.
 Intra oral
e.g. mandibular symphysis, anterior border of ramus of
mandible, extraction site, tori, exostosis, maxillary
tuberosity & edentulous ridge.
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11. IDEAL CHARACTERISTIC OF BONE
GRAFT
Non toxic
Non antigenic
Resistant to infection
No root resorption or ankylosis
Strong and resilient
Easily adaptable
Readily and sufficiently available
Minimal surgical procedure
Stimulates new attachment
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12. ACCORDING TO BIOLOGICAL MECHANISM
TYPES OF BONE GRAFT
Ellgaard et al & Nielson et al ----- graft material may be
 Osteogenic
 Osteoconductive
 Osteoinductive
 Osteopromotive
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13. STRUCTURE OF BONE GRAFT
 Cortical bone grafts are used primarily for structural
support, and cancellous bone grafts for osteogenesis.
Structural support and osteogenesis may be combined
 this is one of the prime advantages of using bone graft.
Probably all or most of the cellular elements in grafts
(particularly cortical grafts) die and are slowly replaced
by creeping substitution, the graft merely acting as a
scaffold for the formation of new bone.
 In hard cortical bone this process of replacement is
considerably slower than in spongy or cancellous bone.
Although cancellous bone is more osteogenic, it is not
strong enough to provide efficient structural support.
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14.  Once a graft has united with the host and is strong
enough to permit unprotected use of the part, remodeling
of the bone structure takes place commensurate with
functional demands.
 Bone grafts may be cortical, cancellous, or
corticocancellous. If structural strength is required,
cortical bone grafts must be used. However, the process
of replacement produces resorption as early as 6 weeks
after implantation.
 Drilling holes in graft does not appear to accelerate the
process of repair, but it may lead to early formation of
biologic pegs that enhance graft union to host bone.
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15. INDICATION
 Jaw resection following malignancy
 In orthognathic surgery
 Extensive trauma
 As an onlay material in facial esthetic surgery
 As a composite cartilage ( bone graft in reconstruction of
TMJ)
 Large bony defect created by cyst & tumours
 In pre-prosthetic surgery as an onlay
 In implantology
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16. IN PERIODONTAL SURGERY
Deep Intraosseous Defects
Tooth Retention
Support for Critical Teeth
Bone Defects Associated With Aggressive Periodontitis
Esthetics (Shallow Intraosseous Defects)
Furcation Defects
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17. GRAFT HARVESTING PROCEDURE
Intra oral sources
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18. INDICATION OF RAMUS OF MANDIBLE
 Localized moderate to severe atrophy/ defect
 One- to four-tooth edentulous span (unilateral ramus
harvest)
 Onlay veneer augmentation especially
—Thin posterior mandible
—Single tooth sites
 Third molar extraction
 Donor site combinations (chin, tuberosity, and tibia)
 Inadequate available bone for symphysis harvest
 Craniofacial augmentation of malar region, repair of
orbital floor
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19. ANATOMICAL LIMITS OF RAMUS
 Coronoid process, molar teeth, inferior alveolar canal &
width of posterior mandible.
 Thickness of ramus may be evaluated by intra oral
palpation, an antero-posterior cephalometric radiograph
or computerised tomography.
 A panoramic radiograph is essential in evaluating the
posterior mandible as a donor site.
 If inferior alveolar canal is positioned superiorly in
relationship to external oblique ridge is <1 cm in width
then other donor site should be considered.
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20. RAMUS OF MANDIBLE
Bone block is harvested from
anterior border of ramus of
mandible.
Ramus area is accessed by
using an extension of
commonly used envelop flap for
third molar extraction.
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21.  4 osteotomies are made through outer cortical bone to
harvest the ramus
External oblique osteotomies
Superior ramus cut
Anterior body cut
Inferior ramus cut
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22. incision is made in buccal vestibule, medial to external
oblique ridge & extended anteriorly & laterally to
reteromolar pad,
extended anteriorly into buccal sulcus of second molar
A mucoperiosteal flap is reflected
Lateral surface of mandibular ramus is exposed by blunt
dissection, periosteum is kept out of the way with a toe
out retractor.
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First pilot holes drilled through the cortex
along planned osteotomy & connected using
the bur or reciprocating saw
External oblique osteotomy may be extended
anteriorly into body of mandible as far as distal
aspect of first molar area
Superior / sagittal osteotomy performed next ,
starting from superior point of external oblique
osteotomy ,  to oblique ridge
Anterior vertical osteotomy performed in
mandibular body , extending inferiorly from
2nd & 1st molar region .

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Partial thickness inferior osteotomy
connecting superior ramus & anterior
body cut
A shallow cut is made into cortex only to
create a line of fracture
A thin chisel may be gently malletted
along entire length of external oblique
osteotomy , taking care to parallel lateral
surface of ramus
A wider wedge chisel or potts elevator is
inserted & leverd to pry buccal segment
free & split the graft

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26. RAMUS GRAFT CONTRAINDICATIONS/
LIMITATIONS
 Thin ramus (< 10 mm)
 Superior position of mandibular canal
 Third molar pathology
 Limited jaw opening
 Previous sagittal split osteotomy
 Severe atrophy/larger alveolar defects
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27. ANATOMICAL LIMITS OF SYMPHYSEAL GRAFT
 Tooth roots
 Mental foramina
 Inferior cortical border
 Lingual cortex
average interforaminal distance is approximately 5cm
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28. SURGICAL PROTOCOL
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LA, rectal & intravenous diazepam / conscious sedation
Mandibulal symphysis is exposed through an intersulcular incision &
two vertical releasing incision anterior to sec premolar region
Vestibuar incision is made in mucosa between canine
teeth at least 1 cm beyond the MGJ
Or

29. Mucoperiosteal flap is raised at facial
side towards the base of mandible to the
level of pogonion
Outline the graft to be harvested by
piezosurgery / fissure bur 3-5mm below
root apices & 4 mm above the lower
border of mandible
Osteotome is used to free the block graft
& osteotomies extended through outer
cortex.
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A bone chisel is tapped along osteotomy to deliver the graft
Bone wax or hemostatic dressing
(collagen or gelatin sponge)
placed into area of heavy osseus-
bleeding

31. IN SITU ONLAY GRAGTING
Stimulation of natural bony wall, an artificial shelf of Ti
mesh held by an autologous block with growth factors
products on labial surface is created to increase 3
dimensional bone volume
Apical to recipient site basal bone is as thick as donor site,
secondary operative site is not needed
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32. LA
A crestal incision & two diverging vertical release are made
Labial surface of resorbed ridge is exposed by subperiosteal dissection
extended to anterior nasal spine
After confirmation of needed bone volume osteotomy was initiated by piezo
surgery
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Two rectangular cuts are made 4mm in depth, involved both cortical &
cancellous bone
Superior cuts are at least 2mm from nasal spine, lateral cuts 1mm from
adjacent teeth
blocks are levered out using a thin chisel
cortical bone of recipient site perforated with a round bur under saline
irrigation

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35. Bone blocks are reshaped by eliminating sharp edges & secured in place using
Ti screw
Ti mesh is curved & placed over bone block t o over correct the
labial contour
Inorganic bovine bone substitute ( bio-oss) used to fill space underneath
Mesh is secured with resorbable suture
CGF was applied as a membrane to cover the mesh
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36.  Donor site is also restored with bio-oss .
 Passive primary closure is achieved by adequate
periosteal release at the base of elevated flap & careful
interuptted suture
 4 months after augmentation grafted is re-entered, mesh
& screws are removed
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37. Extra oral sources
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38. GRAFT FROM CALVARIUM
 Most common donor site for extended augmentation
procedure is iliac crest.
 Bone resorption of almost 50% is depicted after 6
months grafting with free bone transplant from iliac crest
.
 With respect to calvarial bone, resorption is reported to
be minimal
 Smolka & collegues reported volumetric bone reduction
of 19.2% after 1 year.
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39.  Calvarial bone graft is first described as osteocutaneous
vascularized flap in 1890.
 Abramson & tessier popularized the use of free outer
table calvarial bone graft.
 Calvarium composed of two parallel layers of cortical
bone separated by a thin layer of cancellous bone.
 Mean thickness of adult skull ranges from 6.80-7.72mm
but can deviate from 3mm-12mm.
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40. INDICATION
Severe and complex alveolar ridge defects in the maxilla
or mandible induced by trauma or bone atrophy
Insufficient amount of horizontal and/or vertical alveolar
bone (class V and VI according to cawood and Howell
classification)16 not permitting conventional
Implant placement and subsequent implant retained
rehabilitation
Patient’s demand of an implant-retained Rehabilitation
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A vertical hemicoronal incision in craniocaudal direction is made on
parietal scalp length of incision is dependant upon quantity of bone needed
Onlay bone blocks from outer cortex are harvested
(calvarial split bone graft)
Desired dimension of graft block is outlined with round burs under
constant irrigation, bur should reach cancellous bone, indicated by
bleeding, but should not penetrate inner cortex

42.  Block graft are segmented in smaller grafts to facilitate
harvesting & removed using curved chisel
 The peripheral edges of donor sites were beveled &
smoothed with a large bur, & donor site is closed with
multilayered suture.
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44. CONTRAINDICATION
Extensive sagittal misrelationship between maxilla and
mandible, which can not be compensated by calvarial bone
grafts because of the limited thickness of such grafts and thus
requiring other surgical procedures (e.g., onlay grafting with
thicker iliac bone grafts or le fort I osteotomy)
Extensive vertical misrelationship between maxilla and
mandible, which can not be compensated by calvarial bone
grafts because of the limited thickness of the grafts and thus
requiring other surgical procedures (e.g., distraction
osteogenesis)
Defects resulting from oral cancer treatment (radical surgery
in the head and neck region)
Patients with thin calvaria (<5 mm)
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45. ILIAC CREST
The iliac crest is an ideal source of bone graft
because it is relatively subcutaneous, has natural
curvatures that are useful in fashioning grafts,
has ample cancellous bone, and has cortical bone
of varying thickness. Removal of the bone
carries minimal risk and usually there is no
significant residual disability. The posterior third
of the ilium is thickest.
Large cancellous & corticocancellous graft may be
obtained from anterosuperior iliac crest &
posterior iliac crest
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46. Anterior iliac grafts
Large grafts of cancellous & corticocancellous bone can be
harvested from anterosuperior iliac crest.
Incise with a cautery knife along the iliac crest, avoiding
muscles. Subperiosteally, dissect the abdominal
musclature & subsequently iliacus from inner wall of
ilium.
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47. patient lie supine with a small sand bag under the
gluteal region to lift the iliac wing away from the operation table.
A gentle upward pull is made using
the edge of ulnar aspect of the hand placed on the iliac
fossa to lift upward the skin over iliac crest
A marker is used to mark the skin that lie over the iliac
crest from the anterior superior iliac spine to the
posterior superior iliac spine
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48. Incision is made over the mark and deepened to the
deep fascia, which is incised.
A small blade osteotome (1cm wide blade) is used
to elevate the musculofascial attachment of the abdominal wall muscles to the iliac
crest with about 2mm of bone thickness
The length of the graft will
determine the extent of the incision.
The use of small blade osteotome will allow for osteotomy line to follow the curve
of the iliac crest or a thin narrow blade saw should be used
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49. outline the area to be harvested with straight & curved
osteotomes. Cut the stripes, which will be removed.
Anterior column just above the acetabulum is quite thick.
Harvest corticocancellous strips with a gouge.
Remove additional cancellous bone with gouge & curretts.
Don’t broach the outer table.
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Allografts

51. ALLOGRAFT
Harvesting procedure for autograft requires surgery at a
donor site & resultant increased morbidity, operative
time & cost.
Allogenic graft harvested from cadaver have proven to be
clinically useful when aultologous bone is limited.
Only FDBA is used in onlay grafting.
DFDBA does not provide structural support.
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52. Benefits Of Allograft
Reducing operative time & anesthesia time
Less discomfort & morbidity
No significant allergic reaction & rejection
No unexpected antibodies after transplantation
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53. Antibiotic & steroid is given to patient 1
hour before surgery
Rinse mouth with clorhexidine & LA
A crestal incision ( at top of edentulous
crest ) & 2 vertical releasing incisions are
performed
A full thickness flap is raised, palatal flap
is held no. 3 suture.
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54. Defect is determined size shape of
block needed recipient site undergoes
recontouring & perforated with
fissure bur to induce bleeding &
promote revascularization of graft
Allogenic cortico-cancellous graft is
restored in rimafycin solution &
adopted to atrophic ridge
Block were stabilized on residual ridge
with self tapping screw until head
reached surface of bone allograft.
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55. Additional cancellous chips obtained
from allogenic bone is placed at
periphery of block graft to fill gap
between graft & recipient site
Periosteal fenestration is performed at
the base of buccal flap to obtain a
tension free adaption of wound margin
Suture placed, removed after two
weeks
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56. COMPLICATIONS
Incision dehiscence at donor site
Nerve paresthesia
Altered sensation of teeth proximal to graft
Donor site infection
Non vascularized corticocancellous block graft from
endochondral donor site have losy favor in the treatment
of continuity defects & ridge augmentation for soft tissue
supported prosthesis.
Hematoma formation
Intra oral scar formation
Post operative edema & pain
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57. FATE OF BONE GRAFT
 Once the material is placed in the bony defect it may act
in a number of ways which may decide the fate of the
graft material.
 The various possibilities include:
Bone graft material may have no effect at all.
The bone graft material may act as a scaffolding material
for the host site to lay new bone.
The bone graft material may itself deposit new bone
because of its own viability.
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58. BONE HEALING
Procallus formation
Callous formation
Remodelling
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Thank y