Dental implants
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Transcript of Dental implants
Dental implant is
an artificial titanium
fixture
which is placed surgically into the
jaw bone to
substitute for a missing
tooth and its root(s).
WHAT IS A DENTAL IMPLANT?
In 1952, Professor Per-Ingvar Branemark,
a Swedish surgeon, while conducting research
into the healing patterns of bone tissue, accidentally
discovered that when pure titanium comes into
direct contact with the living bone tissue, the two
literally grow together to form a permanent
biological adhesion. He named this phenomenon
"osseointegration".
History of Dental Implants
All current implant
designs are
modifications of this
initial design
First Implant Design by Branemark
STEP 1: INITIAL SURGERY
STEP 2: OSSEOINTEGRATION PERIOD
STEP 3: ABUTMENT CONNECTION
STEP 4: FINAL PROSTHETIC
RESTORATION
Surgical Procedure
Fibro-osseous integration
• Fibroosseous integration
– “tissue to implant contact with dense collagenous
tissue between the implant and bone”
• Seen in earlier implant systems.
• Initially good success rates but extremely
poor long term success.
• Considered a “failure” by todays standards
Microscopic
Osseointegration • Success Rates >90%
• Histologic definition
– “direct connection between living bone and load-bearing endosseous implants at the light microscopic level.”
• 4 factors that influence: Biocompatible material
Implant adapted to prepared site
Atraumatic surgery
Undisturbed healing phase
Soft-tissue to implant interface • Successful implants have an
– Unbroken, perimucosal seal between the soft tissue and the implant abutment surface.
• Connect similarly to natural teeth-some differences.
– Epithelium attaches to surface of titanium much like a natural tooth through a basal lamina and the formation of hemidesmosomes.
Soft-tissue to implant interface
• Connection differs at the connective tissue level.
• Natural tooth Sharpies fibers extent from the bundle bone of the lamina dura and insert into the cementum of the tooth root surface
• Implant: No Cementum or Fiber insertion.
Hence the Epithelial surface attachment is IMPORTANT
Endosteal Implants
The “Parts”
• Implant body-fixture
• Abutment (gingival/temporary healing vs. final)
• Prosthetics
Clinical Components
abutment
Surgical Phase- Treatment Planning
• Evaluation of Implant Site
• Radiographic Evaluation
• Bone Height, Bone Width and Anatomic considerations
Basic Principles
• Soft/ hard tissue graft bed
• Existing occlusion/ dentition
• Simultaneous vs. delayed reconstruction
Anatomic Considerations • Ridge relationship
• Attached tissue
• Interarch clearance
• Inferior alveolar nerve
• Maxillary sinus
• Floor of nose
Limitations to Implant placement in the Maxilla
• Ridge width
• Ridge height
• Bone quality
Anatomic Limitations
Buccal Plate 0.5mm
Lingual Plate 1.0 mm
Maxillary Sinus 1.0 mm
Nasal Cavity 1.0mm
Incisive canal Avoid
Interimplant distance 1-1.5mm
Inferior alveolar canal 2.0mm
Mental nerve 5mm from foramen
Inferior border 1 mm
Adjacent to natural tooth 0.5mm
Placement of
healing abutment
Patient Evaluation
• Medical history
– vascular disease
– immunodeficiency
– diabetes mellitus
– tobacco use
– bisphosphonate use
History of Implant Site
• Factors regarding loss of tooth being replaced
– When?
– How?
– Why?
• Factors that may affect hard and soft tissues:
– Traumatic injuries
– Failed endodontic procedures
– Periodontal disease
• Clinical exam may identify ridge deficiencies [email protected]
Functional examination
Examination of smile:
Ackerman et al differentiated between two types of smile:
- posed smile (social smile, forced smile) …
voluntary, reproducible.
- spontaneous smile ( enjoyment smile) …
involuntary, induced by joy.
Examination of smile
Ackerman et al used a “smile mesh” computer program to
analyze photographs of posed smiles using the Occlusal Plane
and the Dental Midline as reference planes.
He concluded that the posed smile is reproducible if
photographs were taken On The Same Day
- posed smile … the smile-line is at the gingival margin.
- lower smile-line … senile appearance.
Smile related to natural dentition: (SMILE LINE)
Smile Line
• One of the most influencing factors of any prosthodontic restoration
• If no gingival shows then the soft tissue quality, quantity and contours are less important
• Patient counseling on treatment expectations is critical
SMILE LINE FEMALE MALE MORE GINGIVAL DISPLAY LESS GINGIVAL DISPLAY
MORE LOWER INCISOR SHOW
SMILE ARC: - Consonant the curvature of the
max. incisors is parallel to that of the
lower lip.
- nonconsonant the curvature of
the max. incisors is flat … senile
appearance.
Transverse dimension of smile:
- broad smile … 1st molar may be shown at the commissures.
- buccal corridors … improved by :
1- maxillary widening.
2- ,, advancement.
Biocompatibility of Material
Desired Mechanical Properties
• High yield strength
• Modulus close to that of bone’s
• Built-in margin of safety: Changes in environment around implant
Surfaces
• Composition
• Ion release
• Surface modifications
Metallic Implant Surface
Problem:
Implant surface change with time due to oxidation, precipitation…
Possible solutions:
• Oxide layers ( minimize ion release)
• Prosthetic component from noble alloys
• Phase stabilizers other than Al & V (eg. Ti-13Nb-13Zr, Ti-15Mo-2.8Nb )
• Surface Modifications
Screw Implants
(Left to Right: TPS screw,
Ledermann screw,
Branemark screw, ITI
Bonefit screw)
Cylinder Implants
(Left to Right: IMZ, Integral,
Frialit-1 step-cylinder,
Frialit-2 step-cylinder)
Types of Implants
First Surgical Phase (Implant Placement)
Under Local anesthetic the dentist places dental
implants into the jaw bone with a very precise
surgical procedure. The implant remains covered
by gum tissue while fusing to the jaw bone.
Second Surgical Phase (Implant Uncovery)
After approximately six months of healing. Under
local anesthetic, the implant root is exposed and a
healing post is placed over top of it so that the
gum tissue heals around the post.
Prosthetic Phase (Teeth)
Once the gums have healed, an implant crown is
fabricated and screwed down to the implant.
Procedure
Replace a missing tooth
What Is A Dental Implant?
Replace multiple missing teeth
Replace an edentulous arch
Dental implants are used to:
• There is a clear benefit to receiving dental implants
• Quality of life improves
• Diet and nutrition are positively impacted
• Positive impact on leisure activities
• Disadvantage of cutting down perfectly healthy teeth
Implant vs Conventional Bridges vs. Removable Dentures
Patients want:
Patient Friendly Procedures
Fast procedures
Minimally invasive procedures
Long lasting results
Good esthetics
• Transition from 2-stage to 1-stage procedures
• Immediate load implants
• Less invasive dental implant therapy
• Tilted implants, guided flapless surgery
• Advances in ceramic materials create a shift from
function to esthetics
Doctor Friendly Procedures
Concerns About Recommending
Dental Implants for the Elderly Fact or
Fiction…
Longer healing time
Inadequate osseointegration of implants
Loss of implants due to inadequate oral hygiene
Patient’s desire and expectations for dental implants may differ with age
Patient’s Expectations
• Increased resistance to implant surgery - “I’m too old”.
• Long-term edentulous patients may be more tolerant to ill-fitting conventional dentures.
• Recommendations for implant-assisted restorations should occur early in edentulism.
• Elderly patients may take a greater period of time to adapt to a new prosthesis.
Success Rate of Implant
Placement
• Success rate of implants in the healthy
elderly population is the same as that
of younger age groups.
• Degree of osseointegration with
healthy geriatric patients is comparable
to that of the younger population.
Mandibular Overdentures
• Improve the stability and retention of the denture.
• Can be placed over tooth roots or over implants.
• Tooth roots provide sensory feedback but can decay or lose support due to periodontal disease or fracture.
• Both tooth roots or implants will help retain the bone in the mandibular ridge.
• Tooth replacement with implant-supported or assisted
dentures provides greater patient satisfaction with
comfort and chewing.
• Stability and retention of denture is improved.
Growing Need for Satisfactory
Tooth Replacement
Risk Factors for Dental
Implant Success in the Elderly
• Oral Hygiene
• Xerostomia
• Cardiovascular disease
• Diabetes
• Osteoporosis
• Cancer
Implant therapy should be considered as a medical model in
the geriatric population.
Lessened Manual Dexterity and
Visual Acuity May Affect
Oral Self Care Oral Hygiene
Success rate may be comparable to younger age groups when… • Appropriate modifications of oral health aids are made.
• When adequate instruction and recall intervals are
maintained.
• Less complicated designs of implant abutments are utilized.
SURGICAL REQUIREMENTS
Standardised surgical protocol
Surgical environment
Implant equipment - reusable
- disposable/single use
Fully evaluated and prepared patient
Trained staff
STAINLESS STEEL
• Guide drill
• 2mm twist drill
• Pilot drill
• 3mm twist drill
• Countersink
SURGICAL PRELIMINARIES
• Induction of anaesthesia
• Endotracheal intubation
• Throat pack
• Scrub and gown
• Surgical preparation
• Draping
SURGICAL PROCEDURE
• Local Anaesthetic
• Try in stent
• Tattoo
• Surgical incision
• Flap reflection
• Flap retraction
• Try in stent
• Smooth ridge
• Use stent
• Guide drill
• Small twist drill
• Pilot drill
• Large twist drill
• Depth guide
SURGICAL PROCEDURE
• Countersink
• Fixture insertion
• Cover screw
• Debridement
• Closure
SURGICAL PROCEDURE
POSTOPERATIVE CARE
• Haemostasis
• Analgesia
• Antibiotic regime
• Chlorhexidine mouthwash
• Suture removal
• Temporary prosthesis
SECOND STAGE
• Soft tissue
• Bone removal
• Cover screw removal
• Healing abutment
• Replacement
• Dressings
KEY POINTS
• Implant positioning - bucco/lingual
- axial
- separation
• Drill speeds - 2000rpm
- 20rpm
• Torque
• Irrigation
MAXILLARY IMPLANTS
• Lack of well defined cortex
• Poorer quality cancellous bone
• Lack of bucco/lingual width
• Reduced height of available bone
• Proximity of anatomical structures- nose
- antrum
- incisive canal
COMPLICATIONS
• Preoperative
• Perioperative
• Postoperative
• Transient
• Persistent
• Permanent
• Soft tissue
• Hard tissue
SERIOUS COMPLICATIONS
– Jaw fracture
– Haemorrhage
– Ingestion
– Inhalation
– Neurological
– Death
COMPLICATIONS
• Patient selection – Psyche – Anatomy – Systemic disease
• Implant factors • Surgical • Prosthodontic • Errors in judgement • Deviation from established protocol
ANATOMY
• Unsuitable morphologically
• Reduced bone density
• Reduced bone volume
• Attached tissue
• Nerve position
PREVENTION OF NERVE DAMAGE
• CT
• Bone density measurement
• Drill sleeves
• Discretion is better part of valour
COMPLICATIONS
Peroperative
– Failure to obtain anaesthesia
– Haemorrhage
– Stuck implant
– Loose implant
– Lost implant
SURGICAL FAILURE
• Poor planning
• Poor surgical technique
• Lack of precision
• Thermal injury
• Faulty placement
• Damage to adjacent structures
• Wound dehiscence
• Infection
• Mucosal perforation
• Fistula formation
• Anatomical - antral
- nasal
- neurological
COMPLICATIONS
STAGE ONE SURGERY
• Failure to obtain anaesthesia
• Faulty placement
• Anatomical
• Surgical
SURGICAL
• Stripped bone threads
• Exposed implant threads
• Fractured drill
• Sheared implant hex
• Excessive countersink
• Eccentric drill
Second stage
– Loose implant
– Excess bone coverage
– Exposed threads
– Coverscrew problems
COMPLICATIONS
STAGE TWO SURGERY
• Wrong abutment length
• Faulty abutment seating
• Retained sutures
• Gingival hyperplasia
• Mobile tissue
• Destroyed cover screw hex
• Failure of integration
FAULTY PLACEMENT
• Labial / buccal
• Lingual
• Too close
• Straight line in mandibular anteriors
• Angulation
• Divergence
• Correct by use of a surgical template
POSTOPERATIVE
• Fascial space infections
• Haematoma
• Jaw fracture
• Sinusitis
• Wound dehiscence
WOUND DEHISCENCE
• Poor flap design
• Poor surgical technique
• Poor repair
• Poor tissue quality
• Previous surgery
• Underlying medical condition
• Superficial implant placement
PROSTHODONTIC
• Avoid premature loading
• Passive fit
• Good design
• Good oral hygiene
• Loss of integration
• Soft tissue problems
• Oral hygiene and maintenance
• Retrievable v cemented
COMPONENT FAILURE
• Fractured fixture
• Fractured abutment screw
• Fractured punch blade
• Fractured screw driver tip
• Fractured castings
MANAGEMENT OF FAILURE
• Failing implants FAIL
• Removal
• Abandon
• Alternative site
• Larger diameter
• Replacement after healing
Radiographic Examination
• Panoramic radiograph
• 20 to 30% distortion/magnification of the anatomic structures
• Buccal to lingual width will not be appreciated
• Alveolar bone height, adjacent teeth and anatomic structure
Diagnosis and Treatment Planning For Bone Augmentation
Factors that impact on fit: atrophy
1. Atrophy a. Decreasing bone b. Increasing soft tissue
1
2
3
4
Factors that impact on fit: atrophy
1. Atrophy a. Decreasing bone b. Increasing soft tissue
Factors that impact on fit: atrophy
1. Atrophy a. Decreasing bone b. Increasing soft tissue
Clinical Examination
• Minimal obtain 1 to 2mm of attached gingiva
• Cross section of the alveolar depicting periodontal probe placement for “sounding the bone”.
• To determine bone width
• Cutting the study model in the exact vertical location
Diagnosis and Treatment Planning For Bone Augmentation
To Determine Bone Width
Harry Dym, Orrett E. Ogle: Atlas of Minor Oral Surgery. W.B. Saunders company. 2001
GRAFTING
Autogenous - Local symphysis third molar angle tuberosity - Distant rib iliac crest tibia calvarial Allogenic - frozen - freeze dried - demineralized
BIOMATERIALS
- methyl methacrylate - silicone - proplast - teflon - calcium phosphates - plaster of paris - tricalcium phosphate - hydroxyapatite - goretex
FREEZE DRIED BONE
• Commercial preparation
• Multiple donors
• Screened for HIV, Hep B and C
• Sterilised by irradiation
• Risk of prion borne disease
INDICATIONS FOR GRAFTING
• Anterior maxilla
• Posterior maxilla
• Anterior mandible
• Posterior mandible
• After resection
• Post traumatic
TECHNIQUES
• Cortico-cancellous blocks
• Trephined core
• Sinus Lift
• Vascularised bone flap
Radiological/Imaging Studies
• Periapical radiographs
• Panoramic radiograph
• Site specific tomograms
• CAT scan (Denta-scan, cone beam CT)
Anatomic Limitations
Buccal Plate 0.5mm
Lingual Plate 1.0 mm
Maxillary Sinus 1.0 mm
Nasal Cavity 1.0mm
Incisive canal Avoid
Interimplant distance 1-1.5mm
Inferior alveolar canal 2.0mm
Mental nerve 5mm from foramen
Inferior border 1 mm
Adjacent to natural tooth 0.5mm
Types of Bone Grafts
• Autograft – A graft taken from on anatomic location and placed in another
location in the same individual(e.g., iliac crest)
• Allograft – A graft taken from a cadever treated wit certain sterilization and
antiantigenic procedures and placed into a living host
• Alloplast – A chemically derived nonanimal material
• Xenograft – A graft taken from a nonhuman host for implantation into a human
host
Biology of Bone Grafts
• Phase I
– Osteogenesis: Immediate proliferation of transplanted osteocytes and subsequent formation of osteoid(immature bone)
• Phase II
– Osteoinduction: inducement of mesenchymal cells to produce bone(BMP)
– Osteoconduction: framework or scaffold for the formation of new bone tissue
Autogenous Bone Graft
• “Gold standard” – Standard by which other materials are judged
• May provide osteoconduction, osteoinduction and osteogenesis
• Drawbacks
– Limited supply
– Donor site morbidity
Autogenous Bone Grafts
• Cancellous
• Cortical
• Free vascular transfers
• Bone marrow aspirate
Cancellous Bone Grafts
• Three dimensional scaffold (osteoconductive)
• Osteocytes and stem cells (osteogenic)
• A small quantity of growth factors (osteoinductive)
• Little initial structural support
• Can gain support quickly as bone is formed
Cortical Bone Grafts
• Less biologically active than cancellous bone
– Less porous, less surface area, less cellular matrix
– Prologed time to revascularizarion
• Provides more structural support
– Can be used to span defects
• Vascularized cortical grafts
– Better structural support due to earlier incorporation
– Also osteogenic, osteoinductive • Transported periosteum
Bone Marrow Aspirate
• Osteogenic
– Mesenchymal stem cells (osteoprogenitor cells) exist in a 1:50,000 ratio to nucleated cells in marrow aspirate
– Numbers decrease with advancing age
– Can be used in combination with an osteoconductive matrix
Autograft Harvest
• Cancellous
– Iliac crest (most common)
• Anterior- taken from gluteus medius pillar
• Posterior- taken from posterior ilium near SI joint
– Metaphyseal bone
• May offer local source for graft harvest – Greater trochanter, distal femur, proximal or distal tibia,
calcaneus, olecranon, distal radius, proximal humerus
Autograft Harvest
• Cancellous harvest technique
– Cortical window made with osteotomes
• Cancellous bone harvested with gouge or currette
– Can be done with trephine instrument
• Circular drills for dowel harvest
• Commercially available trephines or “harvesters”
• Can be a percutaneus procedure
Autograft Harvest
• Cortical
– Fibula common donor
• Avoid distal fibula to protect ankle function
• Preserve head to keep LCL, hamstrings intact
– Iliac crest
• Cortical or tricortical pieces can be harvested in shape to fill defect
Bone Allografts
• Cancellous or cortical
– Plentiful supply
– Limited infection risk (varies based on processing method)
– Provide osteoconductive scaffold
– May provide structural support
Bone Allografts
• Available in various forms
– Processing methods may vary between companies / agencies
• Fresh
• Fresh Frozen
• Freeze Dried
Bone Allografts
• Fresh
– Highly antigenic
– Limited time to test for immunogenicityor diseases
– Use limited to joint replacement using shape matched osteochondral allografts
Bone Allografts
• Fresh frozen
– Less antigenic
– Time to test for diseases
– Strictly regulated by FDA
– Preserves biomechanical properties
• Good for structural grafts
Bone Allografts
• Freeze-dried
– Even less antigenic
– Time to test for diseases
– Strictly regulated by FDA
– Can be stored at room temperature up
– to 5 years
– Mechanical properties degrade
Bone Graft Substitutes
• Mechanical properties vary widely
– Dependant on composition
• Calcium phosphate cement has highest compressive strength
• Cancellous bone compressive strength is relatively low
• Many substitutes have compressive strengths similar to cancellous bone
• All designed to be used with internal fixation
Grafting of the Extraction Socket
• The teeth are extracted atraumatically preserving the buccal bone.
• All granulation tissue is excised with the use of a surgical curette or a Rongeur.
Bone Morphogenetic Proteins
• Produced by recombinant technology
• Two most extensively studied and commercially available
– BMP-2 (Infuse) Medtronics
– BMP-7 (OP-1) Stryker Biotech
Cortical Onlay Bone Graft
• Inadequate buccal to lingual/palatal width
• Autogenous bone: donor sites-mandibular symphysis, mandibular ramus, calvarium or iliac crest
• Allografts: demineralized freeze dried bone allograft blocks, freeze-dried blocks, and/or particles
Harvesting Techniques III
Interpositional Ridge Graft
• The approximate depth of the osteotomy should be 1cm.
• A bibevel chisel is used to gently outfracture the buccal plate and allow enough width for the proposed implant
• Split ridge technique
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