Dental implants

Dental implants

Islam Kassem

Level 9

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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

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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

Planning of dental implants

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Patient Evaluation

• Medical history

– vascular disease

– immunodeficiency

– diabetes mellitus

– tobacco use

– bisphosphonate use

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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 ikassem@dr.com

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.

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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

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- posed smile … the smile-line is at the gingival margin.

- lower smile-line … senile appearance.

Smile related to natural dentition: (SMILE LINE)

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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

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SMILE LINE FEMALE MALE MORE GINGIVAL DISPLAY LESS GINGIVAL DISPLAY

MORE LOWER INCISOR SHOW

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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.

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SMILE ARC: NORMAL REVERSE (CONSONANT)

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Transverse dimension of smile:

- broad smile … 1st molar may be shown at the commissures.

- buccal corridors … improved by :

1- maxillary widening.

2- ,, advancement.

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BUCCAL CORRIDORS: (NEGATIVE SPACE)

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Alternative Solutions

Partial and Full Dentures

Crowns

Bridges

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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

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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

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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

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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

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Replace a missing tooth

What Is A Dental Implant?

Replace multiple missing teeth

Replace an edentulous arch

Dental implants are used to:

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• 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

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Patients want:

Patient Friendly Procedures

Fast procedures

Minimally invasive procedures

Long lasting results

Good esthetics

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• 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

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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

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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.

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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.

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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.

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• 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

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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.

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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.

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SURGICAL REQUIREMENTS

Standardised surgical protocol

Surgical environment

Implant equipment - reusable

- disposable/single use

Fully evaluated and prepared patient

Trained staff

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EQUIPMENT

FIRST STAGE

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STAINLESS STEEL

• Guide drill

• 2mm twist drill

• Pilot drill

• 3mm twist drill

• Countersink

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TITANIUM

• Tap

• Implant

• Coverscrew

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ANAESTHESIA

• General

• Local

• Sedation

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SURGICAL

• Aseptic technique

• Gentleness

• Precision

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SURGICAL PRELIMINARIES

• Induction of anaesthesia

• Endotracheal intubation

• Throat pack

• Scrub and gown

• Surgical preparation

• Draping

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SURGICAL PROCEDURE

• Local Anaesthetic

• Try in stent

• Tattoo

• Surgical incision

• Flap reflection

• Flap retraction

• Try in stent

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• Smooth ridge

• Use stent

• Guide drill

• Small twist drill

• Pilot drill

• Large twist drill

• Depth guide

SURGICAL PROCEDURE

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• Countersink

• Fixture insertion

• Cover screw

• Debridement

• Closure

SURGICAL PROCEDURE

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POSTOPERATIVE CARE

• Haemostasis

• Analgesia

• Antibiotic regime

• Chlorhexidine mouthwash

• Suture removal

• Temporary prosthesis

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SECOND STAGE

• Soft tissue

• Bone removal

• Cover screw removal

• Healing abutment

• Replacement

• Dressings

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KEY POINTS

• Implant positioning - bucco/lingual

- axial

- separation

• Drill speeds - 2000rpm

- 20rpm

• Torque

• Irrigation

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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

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COMPLICATIONS WITH OSSEOINTEGRATED IMPLANTS

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COMPLICATIONS

• Preoperative

• Perioperative

• Postoperative

• Transient

• Persistent

• Permanent

• Soft tissue

• Hard tissue

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SERIOUS COMPLICATIONS

– Jaw fracture

– Haemorrhage

– Ingestion

– Inhalation

– Neurological

– Death

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COMPLICATIONS

• Patient selection – Psyche – Anatomy – Systemic disease

• Implant factors • Surgical • Prosthodontic • Errors in judgement • Deviation from established protocol

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ANATOMY

• Unsuitable morphologically

• Reduced bone density

• Reduced bone volume

• Attached tissue

• Nerve position

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PREVENTION OF NERVE DAMAGE

• CT

• Bone density measurement

• Drill sleeves

• Discretion is better part of valour

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COMPLICATIONS

Peroperative

– Failure to obtain anaesthesia

– Haemorrhage

– Stuck implant

– Loose implant

– Lost implant

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SURGICAL FAILURE

• Poor planning

• Poor surgical technique

• Lack of precision

• Thermal injury

• Faulty placement

• Damage to adjacent structures

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SURGICAL

• Haemorrhage

• Stuck implant

• Loose implant

• Lost implant

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• Wound dehiscence

• Infection

• Mucosal perforation

• Fistula formation

• Anatomical - antral

- nasal

- neurological

COMPLICATIONS

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STAGE ONE SURGERY

• Failure to obtain anaesthesia

• Faulty placement

• Anatomical

• Surgical

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SURGICAL

• Stripped bone threads

• Exposed implant threads

• Fractured drill

• Sheared implant hex

• Excessive countersink

• Eccentric drill

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Second stage

– Loose implant

– Excess bone coverage

– Exposed threads

– Coverscrew problems

COMPLICATIONS

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STAGE TWO SURGERY

• Wrong abutment length

• Faulty abutment seating

• Retained sutures

• Gingival hyperplasia

• Mobile tissue

• Destroyed cover screw hex

• Failure of integration

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FAULTY PLACEMENT

• Labial / buccal

• Lingual

• Too close

• Straight line in mandibular anteriors

• Angulation

• Divergence

• Correct by use of a surgical template

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POSTOPERATIVE

• Fascial space infections

• Haematoma

• Jaw fracture

• Sinusitis

• Wound dehiscence

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WOUND DEHISCENCE

• Poor flap design

• Poor surgical technique

• Poor repair

• Poor tissue quality

• Previous surgery

• Underlying medical condition

• Superficial implant placement

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PERSISTENT

• Neurological damage

• Aesthetics

• Speech

• Function

• Psychological

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PROSTHODONTIC

• Avoid premature loading

• Passive fit

• Good design

• Good oral hygiene

• Loss of integration

• Soft tissue problems

• Oral hygiene and maintenance

• Retrievable v cemented

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COMPONENT FAILURE

• Fractured fixture

• Fractured abutment screw

• Fractured punch blade

• Fractured screw driver tip

• Fractured castings

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MANAGEMENT OF FAILURE

• Failing implants FAIL

• Removal

• Abandon

• Alternative site

• Larger diameter

• Replacement after healing

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Bone graft for implant dentistry

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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

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Factors that impact on fit: atrophy

1. Atrophy a. Decreasing bone b. Increasing soft tissue

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2

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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

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GRAFTING TECHNIQUES

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GRAFTING

Autogenous - Local symphysis third molar angle tuberosity - Distant rib iliac crest tibia calvarial Allogenic - frozen - freeze dried - demineralized

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BIOMATERIALS

- methyl methacrylate - silicone - proplast - teflon - calcium phosphates - plaster of paris - tricalcium phosphate - hydroxyapatite - goretex

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GRAFTS

• Autogenous bone

• Freeze dried bone

• Synthetic biomaterials

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FREEZE DRIED BONE

• Commercial preparation

• Multiple donors

• Screened for HIV, Hep B and C

• Sterilised by irradiation

• Risk of prion borne disease

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CALCIUM PHOSPHATES

• Plaster of paris

• Tricalcium phosphate

• Hydroxyapatite

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INDICATIONS FOR GRAFTING

• Anterior maxilla

• Posterior maxilla

• Anterior mandible

• Posterior mandible

• After resection

• Post traumatic

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TECHNIQUES

• Cortico-cancellous blocks

• Trephined core

• Sinus Lift

• Vascularised bone flap

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Sinus floor elevation technique

1- Internal

2-External

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Surgical Solutions to Anatomical Limitations

Onlay Bone Graft Sinus Lift

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Radiological/Imaging Studies

• Periapical radiographs

• Panoramic radiograph

• Site specific tomograms

• CAT scan (Denta-scan, cone beam CT)

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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

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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

Study source?

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Contemprary Oral & maxillofacial surgery

Chapter 13

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Thank you

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