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IMPLANTS/BONE GRAFTS POST MAX

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Reed attisha

on 31 August 2014

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Transcript of IMPLANTS/BONE GRAFTS POST MAX

SEPTAE OF UNDERWOOD

MAXILLA

WOLFF'S LAW

Bone remodels in relationship to the forces applied to it

Bone needs
stimulation
to maintain its form and density

The teeth transmit compressive and tensile forces to the surrounding bone.

When a tooth is lost, the lack of stimulation results in a decrease in trabeculae in the area and loss of bone width, then height




Alveolar Bone Resorption

1. Osteclastic activity of the periosteum of the schneiderian membrane

2. Positive intra-antral pressure


Sinus Pneumotization

Conditions are unfavourable, with unique challenges





1-
Soft
Bone
2- Maxillary
Sinus




Anatomical Considerations

Bone density
Maxillary sinus
Alveolar bone resorption pattern
Implant positioning
Implant:Crown ratio




Anatomical Considerations

Maxilla


Anatomical introduction
Anatomical considerations
Treatment Planning considerations
Surgical options
Socket preservation
GBR
Onlay graft
Sinus Augmentation
Innovative Implant Design*
OBJECTIVES


IMPLANTS & BONE GRAFTING IN THE POSTERIOR MAXILLA

Reed Attisha DMD, MD
St. Lawrence Oral & Maxillofacial Surgery
Bone is primarily medullary/spongy

Less osseous density when compared with premaxillary or mandibular bone

The blood supply: I-Max, Superior labial, Anterior ethmoidal



ANATOMICAL INTRODUCTION
Maxillary Sinus
Present at birth
Pneumotizes throughout adulthood
Pyramidal
Each sinus is 15 cc
Reinforced with internal vertical septa, creating further intrasinus cavities
Sinus communicates with middle meatus through the ostium
Schneiderian membrane is adherent to the underlying bone, lined by pseudostratified columnar ciliated epithelium, and is
0.8 mm in thickness
Beneath the schneiderian membrane is highly vascular periosteum

SINUS PNEUMOTIZATION
Bone height is lost due to periodontal disease

Distal molar furcations- difficult hygiene access




Successful implant therapy depends on the presence of adequate
QUANTITY
and
QUALITY
of bone

10x
less bone dense than anterior mandible

D4 bone PLUS thin cortical labial plate compromised initial implant stability












D4 BONE - CONSIDERATIONS

Alveolar Bone Resorption in
presence
of teeth
Alveolar Bone Resorption-
after
extraction
Decrease in bone width at the expense of the labial bony plate

Width of post maxilla decreases at a more rapid rate than in any other region of the jaws

Resorption phenome is accelerated by the loss of vascularization of the alveolar bone and the existing fine trabecular bone type

Ridge shifts towards the palate
until the ridge is resorbed into a medially positioned narrower bone volume; this results in the
buccal cusps of the final restoration often being cantilevered facially
to satisfy esthetic requirements as the expense of biomechanics
BONE LOSS & SINUS PNEUMOTIZATION

Bone Remodelling

Available Space
MESIODISTALLY

Premolar --
1.5mm
from natural tooth

Molar --
2.5 mm
from natural tooth

Desirable – 4mm implant for premolar and 5mm implant for molars


Tx Planning Considerations

Tx Planning Considerations
BUCCOLINGUAL

Implant positioning -- Exit angle of the screw access points towards the inner incline of the buccal cusp

Implant should be placed in the center of the anticipated crown




If significant buccal bone has been lost




Implant placed at the midcrest of the ridge




Results in a buccal restorative cantilever




Increase the risk of abutment /fixure fracture
Screw joint looseing or fracture of the screw




The goal is to minimize the buccal cantilever




NOTE:
With poor implant placement sometimes it is necessary to fabricate the prostheis in
crossbite
with the max buccal cusps occluding in the central groove of the mand post teeth.

horizontal overlap and ridge
relationship in health


tooth loss with minimal ridge collapse
Further resorption creates greater interarch distance

Minimal resorption allows occlusal scheme to remain the same as prior to extraction, and ideal emergence for crown contours


Buccal collapse of the ridges requires implants to be placed in a more lingual position. This creates restorations with buccal over- contouring and unfavourable loading conditions on the implant. The alternative option is to restore with an x-bite relationship.

OCCLUSOGINGIVALLY

1. Adequate space for restoration
2.Adequate osseous volume for placement of the implant



Replacing premolar and molar teeth requires
8-10mm
interocclusally

Opposing dentition
SUPRAERUPTION
--> compromise the restorative space

An
unfavourable
Implant:Crown ratio will cause
crestal bone resorption

Sinus augmentation
provides adequate bone volume to place implants but
does not correct for vertical space deficiencies


Sinus augmentation allows implant placement but the restorative space remains the same
The patient must accept either a long tooth or incorporation of pink ceramics to disguise the tooth length
Implant:Crown is unfavourable
Implant:Crown is favourable
Pneumotized sinus, minimal alveolar bone resorption Implants placed, favourable Implant:Crown
1.25
1
Advanced ridge resorption. Sinus Lift without reconstruction of ridge height leads to less favourable crown to implant ratio

Most difficult area of the oral cavity to place and restore implants in

Softest and least dense bone

Sinus pneumotization

Alveolar bone resorption with many sequelae/treatment considerations




We now know this about the
posterior maxilla
….

DEFICIENT BONE STOCK + SINUS PNEUMOTIZATION

SIMPLE EQUATION
SOCKET PRESERVATION
EXTRACTION SOCKET HEALING
POST-EXTRACTION FACT:
40 % width
and
25% height
is lost within 6 months of extraction in posterior maxilla

GUIDED BONE REGENERATION - GBR
BONE GRAFTING
Autogenous
Osteoinductive, Osteoconductive, Ostegenic



Allogenic
Osteoconductive



Xenogenic
Osteoconductive



Alloplast
Little osteoinductive activity

ONLAY GRAFTING
Three conditions necessary for the new growth of bone into a surrounding defect
Presence of a blood clot
Preserved osteoblasts
Contact with living tissue

Placing an inert membrane with an appropriate pore size, which hinders the penetration of undesirable cells, a space is created that permits the entrance of osteogenic and angiogenic cells from the adjacent bone marrow to populate the area and proliferate.

The amount of new bone formed is contingent upon the amount of space created by the membrane.


GBR
Space Making Principle
Osteopromotion Principle
SINUS AUGMENTATION
2 Approaches:
Internal
&
External
OSFE 1-2mm gain
BAOSE 2-4mm gain
LATERAL WINDOW APPROACH
No augmentation needed
Internal lift with simultaneous implant placement
Lateral Window Approach with simultaneous implant placement
Lateral Window Approach with DELAYED implant placement
THANK YOU
Trabecular Metal Technology
A three-dimensional material, not an implant surface or coating

Its structure is similar to cancellous bone

Consistent, open and interconnected network of pores is designed for bone on-growth and in-growth, or
osseoincorporation


SA-2
SA-3
SA-4
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