06 success and failure of implants

7/30/2019 06 Success and Failure of Implants

1/28

CONTENTS

INTRODUCTION

HISTORY

DEFINITIONS

BONE DENSITY A KEY DETERMINANT

DIVISION OF AVAILABLE BONE

PROSTHETIC OPTIONS

QUALITY OF HEALTH/ SUCCESS

CLASSIFICATION OF COMPLICATIONS

IMPLANT FAILURE DUE TO:-

- Systemic Factors

- Psychological Factors

- Operative Errors

PROSTHODONTIC CONSIDERATIONS IN STAGE-I IMPLANTS

IMPLANT DESIGN AND MANUFACTURING, BIOMECHANICS

RELATED TO IMPLANT FAILURE

SOFT TISSUE CONSIDERATIONS

MECHANICAL COMPLICATION MANAGEMENT

SUBMERGED PROFILE OF IMPLANT

SUMMARY

BIBLIOGRAPHY


2/28

Seminar - VI Success & Failures in Implants

SUCCESS AND FAILURE OF IMPLANTS

INTRODUCTION

Implant dentistry is currently being practiced in an

atmosphere of enthusiasm and optimism, because our knowledge

and ability to provide service to our patients has expanded so

greatly in such a short period.

Complications do arise in implant dentistry. These are more

often due to aging, changing health conditions, long-term wear

and tear, poor home care and inadequate professional

maintenance.

Success cannot be guaranteed, what one can guarantee is

to care, to do ones best and to be there to help in the rare

instance that something goes wrong, patient appreciate and

benefit from straight talk.

"Unfortunately failure is often the best teacher".

HISTORY

Egyptian time used to implant extracted teeth of poor

/slaves who would sell it off.

When human teeth not available they started using animal

teeth e.g. goats, dogs and monkeys. Sea shells were also used.

1886 Bugnot attempted to use tooth buds and transplantation of

teeth was tried.

1940 Farmaggini developed screw type of implants.

DEPT. OF PROSTHODONTICS 163


3/28


1952 Dr. Branemark, orthopaedic surgeon, Sweden found that

Titanium implant can be used for bone anchorage (he was doing

research of microcirculation in box repair mechanism in rabbits).

1952 Osseointegration introduced by branemark

1962 Cr-Co implant, failed.

1967 Hodosch used acrylic resin in tooth form.

1966 Linkow introduced blade form implants (Cr-Co-Vanadium).

Later ceramic, Ti-introduced.

Charles weiss Fibro-osseous integration he claimed that fibroustissue will act as periodontal ligament.

1980 Dr. J.P. Branemark brought his research to America.

American technology quickly adapted these principles.

DEFINITIONS

Dental Implant "A substance that is placed into the jaws to

support a crown, or fixed or removable denture".

Ailing Implant "An implant that may demonstrate bone loss

with deeper clinical probing depths, but appears to be stable

when evaluated at 3-4 months interval. A lamina dura may be

present at the borders of osseous defect, possibly indicating astatic of chronicity".

Failing Implant "An implant that may demonstrate bone loss,

increasing clinical probing depth, bleeding on probing and

suppuration. This bone loss may be progressive".

Failed Implant An implant that demonstrates clinical mobility,

a peri-implant radiolucency and a dull sound when percussed.



4/28


Early failures Occurs weeks to few months after placement,

caused by factors that can interfere with normal healing process

or an altered host response.

Late failures Arise from pathological processes that involve a

previously osseointegrated implant.

Peri-implantitis An inflammatory process that affects the

tissue around an osseointegrated implant in function and results

in loss of supporting bone.

Peri-implant mucositis A term used to describe reversibleinflammatory reactions in the mucosa adjacent to an implant.

MISH BONE DENSITY CLASSIFICATION

D1 Dense cortical bone

(8% in anterior mandible)

>1250 hounsfield units (Radiographic bone density) CT-Scan

D2 Thick dense to porous cortical bone on crest and coarse

trabacular bone within.

(Anterior mandible, post-mandible 850-1250 HU)

D3 Thin porous cortical bone on crest and fine trabacular bone

within (Anterior maxilla 350-850 HU)

D4 Fine trabacular bone (Post-maxilla 150-350 HU)

D5 Immature, non-mineralised bone (


5/28


DIVISIONS OF AVAILABLE BONE

Division Dimension Treatment OptionAbundant >5mm width

>10-13 mm height

>7mm length

12 mm length


6/28


PROSTHETIC OPTIONS

FP-I: Fixed prosthesis; Replaces only the crown; looks like a

natural tooth.

FP-II: Fixed; replaces crown and a portion of root; crown contour

appear normal in occlusal half, but elongated/hypercontoured in

gingival half.

FP-III: In addition to FP-2, replaces edentulous site, uses denture

teeth and acrylic gingiva or porcelain to metal.

RP-IV: Removable overdenture; supported completely by implant

RP-V: Removable overdenture; supported by both implant and

soft tissue.

QUALITY OF HEALTH/ SUCCESS

Criterias by Alberktsson et al.

Immobile

Per-implant radiolucency

Vertical bone loss


7/28


with forces of 500gm are clinically used to evaluate tooth/implant

pain/discomfort.

Presence of pain requires removal of implant pain from rigidimplant is early problem, where pain from mobile implant can

occur early /late in treatment.

Tenderness to percussion usually implies healing proximal to

nerve /bone stress beyond physiologic limits. If implant

tenderness immediately postsurgeyr occurs in proximity of

inferior alveolar canal implant unthreaded for few mm and re-

evaluated after 3/more wks for symptoms.

If tenderness is after stage-I healing and not due to surgical

encroachment on an anatomic landmark, stress may be the

causative element.

Treatment stress management:

- Occlusion with parafunctional habits should be addressed in

the presence of implant sensitivity

- Modify prosthesis

- Place additional implants

3. Rigid Fixation:-

Horizontal mobility beyond 0.5mm or any clinically observed

vertical movement under less than 500 gm force.

4. Percussion:

Pain on percussion / function.



8/28


5. Bone loss:-

Rapid progressive bone loss regardless of the stress

reduction and peri-implant therapy, more than half surrounding

bone is lost around on implant.

6. Radiologic Evaluation:

Generalised radiolucence around an implant.

7. Peri-implant disease:

Continued uncontrolled exudates in spite of surgical

attempts at correction.

Sleepers:-

Implants inserted in poor position making them useless for

prosthetic support, but maintains bone height beneath the

mucosa.

8. Probing Depth:-

- Probing pressure 20 gm, sterile periodontal probe used

- Indication of marginal bone/crestal bone loss

- As sulcus depth increases oxygen tension decreased

bacteria grow in implant sulcus.

- Sulcus depth should be maintained at


9/28


9. Bleeding Index (BI):-

Indication of sulcus health:-

- Gingival bleeding when probing is correlated to

inflammation and plaque index.

- Gingivitis, deep sulcular pocket, plaque index, Loe & Silness

Gingival Index.

- Sulcus depth 5mm and BI increased gingivectomy,

revision surgery.

10) Rigid Fixations:-

Means absence of observed clinical mobility. A normal tooth

moves 56 to 73 m. The healthy implant moves


10/28


0 Absence

1 Detectable horizontal movement

2 Visible mobility up to 0.5mm horizontally

3 Severe horizontal movement >0.5mm

4 Visible moderate to severe horizontal and any visible vertical

movement.

Tooth with mobility of 0.5mm, which was due to occlusal

trauma may revert back to normal rigid fixation by removing the

cause, but this rarely occurs in implants.

An implant with >0.5 mm mobility should be removed.

Periotest:

Periotest (Siemens Corporation) is a computer mechanical

device developed by Schulte, that measures the dampening effect

of objects. It develops a force of 12 to 18 gm/n.

The soft surface or mobile object will give higher recordings

that a hard or rigid object. Recordings range from 8 to +50

numbers. Teeth with absence of mobility 8 to +9.

The bone density around the implant may be correlated with

these numbers.

Percussion:-

It is neither an indication of clinical health nor of rigid

fixation. Therefore the ranging sound that occurs on percussion

will be same for both 2 mm of bone and 16mmof bone-implant

interface.



11/28


It can be used to diagnose pain, tenderness with an implant,

but it is misleading if used to determine the status of rigid

fixation.

Bone Loss:-

Crestal bone loss in initial therapy is an indicator of the need

for initial preventive therapy. Whenever possible implant should

be placed at /above the level of bone crest to avoid an increase in

sulcus depth subsequent to abutment placement.

Initial bone loss is due to occlusal traumatic stress, parafunction.

Secondary bone loss due to bacteria and increased stress.

In threaded implant the distance between each thread (thread

pitch) is usually 0.6mm and can be used as radiographic marker.

In general if bone loss is more than the one-half of implant heightis said to be failure regardless of original amount of implant-bone

contact.

Radiographic Evaluation:

One of the easiest clinical tool to assess the implant crestal

bone loss.

- It only illustrates mesial and distal crestal levels clearly,

however, early bone loss is more on facial aspects.

- Parallel IOPA is very difficult to take with implant therefore

apex of implant will be apical to tooth and muscle

attachment.

-Bitewing and periapical radiograph without apex are best to

assess the crestal bone loss.



12/28


- Both the region the thread area must be very clear, if these

borders are fuzzy then radiograph is not said to be

diagnostic for crestal bone loss assessment.

- Peri-implant radiolucency-indication of failure may be due to

bacteria infection, non-rigid fixation, local bone healing

disorders, dehiscence, contamination of drill, overheating of

bone.

Periapical Radiolucency:-

-If accompanied by fistula surgical re-entry and sectioning

of apical portion of implant suggested.

- An absence of radiolucency around an implant does not

mean bone is present at the interface, especially in anterior

mandible. 40% of decrease in density is necessary to

produce traditional radiograph difference because of dense

cortical bone.

Radiograph Schedule:-

- Baseline radiograph at initial DD of prosthesis

- 6 months -> is compared with baseline

- 1 year bitewing radiograph

- If no changes then for every 3 yrs

- If changes reduction of stress, oral hygiene modified

accordingly.

- If bone loss is found after stage-II most commonly due to

parafunction habits.

- Night guards, stress reduction

Peri-implant Disease:



13/28


Always plaque associated:-

- Gingivitis may be ANUG, ulcerative hormonal, drug induced,

spontaneous occurring in tooth and implant.

- Unlike tooth there is no connective tissue attachment barrier

(1mm) to protect crestal bone around an implant.

- Periodontitis may be

Bacterial

Adult onset

Rapidly progressive

Localized juvenile

Prepubertal periodontitis

Term peri-implantitis is used for implants to describe bone

loss around an implant stress induced, bacterial induced/

combination of both.

An exudates/ abscess indicates exacerbation of

periimplant disease and possible accelerated bone loss.

Antibiotics + chlorhexidine after 1 to 2 wks if it remains

surgical reversion of periimplant area.



14/28


Implant Quality Scale

Group Clinical Conditions Management

I (Optimumhealth)

No pain or tenderness onpalpation, percussion, or

function.

Rigid fixation; no horizontal orvertical mobility under 500gload (IM 0).

5mm probing depth and

Reduce stresses.

Drug therapy,antibiotics,chlorhexidine.

Surgical reentry,revision surgery.

Change in prosthesisand/or implants.



15/28


increasing in preceding 3 years.

+/- History of exudates 1 to 2weeks in last 3 years.

+/- Slight radiolucency aroundcrestal portion of implant

1 to 3 bleeding index

IV (Clinical failure any of thefollowingconditions)

Pain on palpation, percussion, orfunction.

>0.5mm mobility horizontally; anyvertical mobility (IM 3 to 4).

Uncontrolled progressive boneloss.

More than loss of bonesupporting the implant.

Uncontrolled exudates.

Generalized radiolucency.

"Sleepers".

Removal of implant

V (Absolutefailure)

Implants surgically removed

Implants exfoliated

Bone graft

This scale was first presented by James later modified by

Mish.

CLASSIFICATION OF COMPLICATIONS

Swedish team (Branemark et al)

I. Loss of bone anchorage

1. Mucoperiosteal perforation

2. Surgical trauma

II. Gingival problems

1. Proliferative gingivitis.

2. Fistula formation

III. Mechanical complications

1. Fixture fractures

2. Fracture of prostheses, gold screws, abutment screws



16/28


UCLA team (Beumer. Moy)

1. Complications in stage I surgery

1. Mental nerve damage

2. Penetration into a sinus, nasal cavity or through

inferior border of the mandible.

3. Excess counter sink

4. Thread exposure

5. Eccentric drills, taps

6. Stripping of threads

7. Jaw fracture

8. Ecchymosis, more common in older patients

9. Wound dehiscence

10. Facial space abscess, submental, submandibular

abscess, Ludwigs angina

11. Suture abscess

12. Loss cover screw.

2. Complication in Stage II surgery

1. Poor selection of fixture height

2. Incorrect fixture placement, more than 350 cannot be

used prosthtically

3. Damaged hex nut on top of fixture

4. Loss abutment

5. Fracture abutment screw6. Early loading by prostheses

7. Poor air-flow pattern with high water design

8. Aspiration of instruments

9. Thread exposure

10. Fixture fractures

11. Excess bone resorption

12. Plaque / calculus formation



17/28


13. Periodontal problems

14. Poor selection of abutment height

3. Prosthetic complications :

1) Insufficient space beneath the fully bone anchored

prosthesis

2) Abutments penetrate through alveolar mucosa

(unattached tissue)

3) Screw fractures: gold or abutment screws

4) Acrylic or porcelain fracture

5) Posterior fixture failures in the maxilla

This library dissertation presents a view of the complication

that arise in the stages of diagnosis, patient selection, counseling,

per-operative procedures, surgical procedures, post insertion and

maintenance stages and their prevention and remedies.

IMPLANT FAILURE DUE TO

i) Systemic Factors:-

Potential medical risks (Matukas 1988):

1. Cardiovascular Heart failure, CHD, hypertension,

unexplained arythmea.

2. Respiratory COPD, chronic obstructive pulmonary disease,

Asthma.

3. GIT Nutritional disorders, Hepatitis malabsorption,

inflammatory bowel disease.

4. Genitourinary Chronic renal failure.

5. Endocrine Diabetes, thyroid disease, pituitary/adrenal

disease.



18/28


6. Musculoskeletal, arthritis, osteoporosis.

7. Neurologic Stroke, Palsy.

Absolute Medical Contraindications:- Pregnancy

- Granulocytopenia

- Steroid use

- Continuous antibiotic coverage

- Brittle diabetes

-Hemophelia

- Ehler-Dahnlos syndrome

- Marfan's syndrome

- Osteo-radionecrosis

- Renal failure

- Organ transplants

- Anticoagulant therapy

- Fibrous dysplasia

- Crohn's Disease

ii) Psychological Factors:

Lack of support

Cognitive difficulty

- Mental retardation

- Dementia

- Psychosis

Emotional problems

Interpersonal problems



19/28


- Behavioral problems

- Problematic attitudes and beliefs.

Basic Recommendations:- Identify patient with significant psychiatric disturbance

Refer to psychologist, if found disturbed

Be sensitive to patient

Maintain good communication

"Meet the mind of the patient, before you meet the mouth of

the patient".

iii) Operative Errors

PROSTHODONTIC CONSIDERATIONS IN STAGE-I IMPLANTS:

1. Post-operative complications that result from stage-I

surgical conditions.

- Haemorhage, haematoma, edema.

- Extensive damage to mucoperiosteum.

2. Anatomic conditions that lead to post-operative

complications

a) Damage to local structures and improper implant

placement

b) Damage to adjacent structures

- Maxillary sinus,

- Post-surgical lip paresthesia/ pain in mandible,

-Placed too close to adjacent tooth pain

c) Bone quality and primary stability of implant



20/28


3. Pre-operative infections:

Insufficient tightening of cover screw

Preoperative contamination

Retained suture

If persists >7days removal of implant

4. Transmucosal overloading and premature loading of

prosthesis

5. Local wound breakdown and mucosal perforation

6. Systemic condition and behavior factors7. Interim prosthetic procedure after stage-II surgery

Prosthesis with increased vertical dimension, occlusal

discrepancies, excessive forces on implant jeopardize

osseointegration.

Post-stage-I Interim RPD

Post-stage-II Interim FPD

Fixed resin bonded interim prosthesis can be made by using

orthodontic retainers and light cured resins. Most of failures

occurs between stage-I implant placement and stage-II abutment

connection.

IMPLANT DESIGN AND MANUFACTURING AS PREDICTORS

IMPLANT FAILURE:

1. Macroscopic structure

Press Fit cylindrical

Hollow vented cylindrical implants

Fluted implantSmooth titanium screw type



21/28


2. Surface Composition:-

i) Ti Ti alloys

- Osteoblasts appear to grow well on Ti

- better bond compared to Co-Cr

ii) Calcium phosphate ceramics

- Bond (better than Ti, (33 times more MOE than bone)

- Poor mechanical properties

iii) Hydroxyapatite and bone growth

-

Most common coating material over implant

- Enhances attachment

iv) Bio-active glass

- Polycrystalline ceramics (Silicon dioxide crystals)

v) Copolymer coating of implants

- Recent elastomer polyethalene oxide polybutalene

terephthalate copolymer

- Growth factor- (BM Protein)

3. Force:- Discussed under

a) Force duration:-

Teeth contacts


22/28


b) Force type Compression, tensile, shear type of force.

3 standard thread designs V-shape

- Square

-Buttress

c) Force Direction Bone undercuts

300 angulation load decreases compression strength by

11%

decreases tensile strength by 25%as angulation increases stress around implant increases

Force angle of thread alters stress

d) Force magnitude will be increased in cantilevers, density of

bone (D4 10 times weaker than D1 bone)

Extreme angulation, parafunctional habits

Prosthodontic Considerations:

1. Forces on Implants:

Vertical forces are tolerated better compared to lateral

bending forces.

2. Tripod Effect:

- Greater the tripod increase resistance to bending

- Large tripod contacts easily achieved in edentulous implant

supported prosthesis

3. Geometric load factors:-

- Fewer than 3 implants

- Implant connected to teeth



23/28


- Implants in a line

- Cantilever extensions

- Occlusal plane beyond implant support

These factors will lead to failure.

4. Crown Implant Ratio:

Larger better tolerated in full arch restoration

Smaller better tolerated in partially edentulous conditions

5. Occlusal design:-

-

Narrow occlusal table

- Centric contacts over implants

- Lingualised occlusion

- In partially edentulous state regular follow up is very much

necessary

- Parafunctional habits patient is informed abut less success

rate

6. Strategic Extractions:-

Periodontaly compromised abutments should be extracted.

7. Single implant restorations:-

Problems include loose screws

Fracture of screws

Loss of osseointegration

Fracture of implants

- Molar restoration on single implant

- Here the wider diameter implants with stronger components

should be used (5mm dia implant is 200% stronger than

3.75 mm dia).



24/28


8. Tooth Implant Connection:-

Tooth Periodontal ligament (moves)

Implant Ankylosed to bone (rigid)

Two problems:-

i. Mobile tooth acts as a cantilever and increases load on

implant

ii. Non-rigid connector will intrude the tooth.

3-options for tooth to implant connection:-i) One implant one tooth rigid connection

- to divide the load

ii) Multiple implant tooth/teeth stress breaking attachment

iii) Multiple tooth abutments incorporated in long span

restorations (here tooth will not support the prosthesis)

SOFT TISSUE COMPLICATIONS:

1. Exposure of cover screw:-

Because of

- Open wound

-Residual suture material

- Poorly adjusted denture - Sore spot

- dehiscence

Treatment

- Eliminate the cause

- Flap surgery to remove granulation tissue

- Gingival grafts



25/28


2. Proliferative gingivitis and fistula

- Peri-implant epithelium grow around abutment and exposed

gold cylinder

Treatment

- Flap surgery, gingivectomy (internal bevel incision)

- Simple circumferential excision for fistula

3. Exposure of fixture threads:

- Because of advanced alveolar ridge resorption

-

Minimal attached gingiva, shallow vestibule

- 1.5% of incidence noted by Adell et al (1981)

Treatment:-

- Bone graft

- Cover with free gingival graft

MECHANICAL COMPLICATIONS AND MANAGEMENT

i) Component Fracture:

Fixture fracture:-

- Remaining portion should be surgically removed with

trephine bur

- Fractured portion is duplicated

- UCLA abutment is fitted to master cast

- This abutment is then screwed into fixture and prosthesis is

connected

ii) Abutment Screw Fracture:

If screw fractures at the level of neck or head of fixture.



26/28


Cut a groove in abutment screw fragment and use smallest

drill to rotate abutment screw.

If it cannot be removed then splitting the fragment willdamage fixture threads.

iii) Prosthesis Fracture:-

- Fully bone anchored prosthesis can fracture at cantilever

section, if appropriate waxing were not followed.

- Framework fracture is not a major complication when

fixtures are in good condition.

iv) Functional Speech Problem:-

Fully bone anchored prosthesis in maxilla can cause

phonetic problems, because of opened interproximal embrasure

areas.

Artificial gingival cascade with silicone material will help to

resolve the problem.

v) Malpositioined Fixtures:-

- Angulated abutments can be used.

- In fully implant supported prosthesis the mesostructural bar

is used.

Mesostructural bar may fracture because of long span,

insufficient implant support, occlusal trauma.

Treatment:-

- If screw retained (fixed detachable) then remove, take

index, and repair.



27/28


- If cemented coping bar fractures use electrodux (intra-oral

Ti-welding).

THE SUBMERGED PROFILE OF IMPLANT

I Vertical height of bone is 2mm apical to an imaginary line

connecting CEJ. Here smile line framed by lip will be agreeable to

the patient.

II The vertical height of bone is 4mm apical to CEJ. Finished

prosthesis will show slight cervical burning at the margins.

III The vertical height of bone is 6mm apical to CEJ. Finished

crown will be longer, it is only acceptable for low lip line patient.

SUMMARY

The success or failure of an implant is as difficult to describe

as the success criteria required for a tooth. The range from health

to disease is similar in both conditions. The primary criteria for

assessing implant quality are pain and mobility. The presence of

either factor greatly compromises the implant, and removal is

usually indicated.

"Prevention is better than cure" the successful management

of implant dentistry depends on the meticulous diagnostic,

treatment planning and surgical skills of the operator.



28/28


BIBLIOGRAPHY:

Contemporary Implant Dentistry, 2nd Edn. Carl E. Misch.

Principles and Practice of Implant Dentistry Charles M.

Weiss, Adam Weiss.

Dental Implants Charles A. Babbush.

Implant therapy Myron Nevins.

Clinical Periodontics & Implantology, 4th edition, Jan Lindhe.

Atlas or Oral Implantology A. Normann Cranin.

Soft tissue and Esthetic consideration in Implant Therapy

Anthony G. Sclar.

Oral Rehabilitation with Implant Supported Prosthesis

V.Jameson Lopez.

JADA Feb 2001, Page 191.

J. Oral & Maxillofac Surgery, Clinics of North America, Vol.6,

No.4. 1994.

J. Prosthet. Dent. 1989, Vol.62, No.5.

J. Prosthet. Dent. 2004, 91-4-319-25.

J. Prosthet. Dent. 2004, 91-4-326

J. Prosthet. Dent. 2004, 91-93-96.

06 success and failure of implants

Documents