failures of dental implants /certified fixed orthodontic courses by Indian dental academy

INDIAN
ACADEMY

DENTAL

Leader in continuing dental education
By
www.indiandentalacademy.com
PUSHKAR GUPTA
PG Student,
Dept. of Prosthodontics

INTRODUCTION
The use of dental implants has enabled the
fabrication

of

restorations

and

highly

functional

improved

the

and

esthetic

predictability

of

treatment. However, at any point during rehabilitation
and maintenance complications and failure can occur.




Improper Patient Selection



Surgical complication

Intraoperative
complication



Postoperative
complication

Prosthetic Complication


IMPROPER PATIENT SELECTION
The critical selection of patients and the critical
application of dental implants are the two most
important pre requisites for the treatment success we
all desire (Lanney 1986)


BONE DENSITY



A key determinant for clinical success



Highest clinical failure rates have been reported
in posterior maxilla



Linkow in 1970 classified bone density into three
categories.

Class I

:

Consist of evenly spaced trabeculae
with small cancellated spaces.

Class II

:

Consist of slightly larger
cancellated spaces with less
uniformity of the osseous pattern

Class III

:

Large marrow filled spaces exist
between bone trabeculae

In 1988 Misch classified bone density into
D1

Dense cortical bone

D2

Thick dense to porous cortical bone on crest
and coarse trabecular bone within

D3

Thin porous cortical bone on crest and fine
trabecular bone within

D4

Fine trabecular bone

D5

Immature, nonmineralized bone



As the bone density decreases the strength of

the bone also decrease.


Stress can be reduced by :
A.
B.

Narrowing the occlusal table design.

C.

Wider implants

D.


decreasing the cantilever length

HA Coatings

0.5mm increase in width – 10% - 15% increase in
surface area.

AVAILABLE BONE


As a general guideline 1.5mm of surgical error is

maintained between the implant and any adjacent
landmark.


The height of the available bone is measured

from the crest of the edentulous

ridge to the

opposing landmark such as the maxillary sinus or
mandibular canal in the posterior region.


The anterior region are limited by the maxillary

nares or the inferior border of the mandible.



After estimating the available bone height by

panoramic
accordingly.

radiograph,

the

implant


is

selected

Another criteria is bone width, which is
measured between the facial and lingual plates at the
crest of the implant site.

Root form implant of 4.0mm crestal diameter
usually require more than 5.0mm of bone width to
ensure sufficient bone thickness and blood supply
around the implant for long term success.





Placing implant of 10mm length in division D bone

without bone augmentation will lead to perforation of
anatomical landmarks or impingement of nerves leading
to parasthesia.


Hence selection of implant after estimating the

available

bone

is

one

of

the

complication and implant failure.

way

of

reducing

DIABETES MELLITUS


More prone to infection



Slow healing  tissue necrosis



A ten day regime of broad spectrum antibiotics

should be begun on the day of surgery to reduce the
risk of infection.


High success rate is reported when dental

implants are placed in diabetic patients whose disease
is under control.



Kapur et al in 1998 compared 37 diabetic

patients

who

received

conventional

removable

mandibular overdentures versus 52 who were fitted
with implant supported ones and concluded that
implants can be successfully used in diabetic patients
under control.


SMOKING


Nicotine  50% reduction in oxygen to the bone



Have greater risk of developing peri implantitis.
Increased resorption of peri implant bone
If untreated
Implant Failure




Failure rate of 11.28% for smokers compared to

4.76% for non smokers have been reported. (Senerby
and Roos).


Smoking cessation will results in improved

periodontal health and improve a patient chance of
successful implant osseointegration.


BRUXISM


The most common cause of early loss of rigid

fixation is parafunctional habits.


Such complications occur with greater frequency

in the maxilla because of decreased bone density.


A 37 – year old patient with a long history of

bruxism recorded a maximum bite force of more than
990 Psi (4-7 times normal).



The best and easiest way to diagnose bruxism is

to evaluate the wearing of teeth.



It is not a contraindication for implant dentistry,

but once the source of additional force on the implant
system is identified, the treatment plan is altered to
lower the negative impact on the implant, bone and
final restoration.


PATIENT UNMOTIVATED TO CONTROL PLAQUE


Not good candidates for dental implant



Accumulation of plaque on the implant surface (if

not treated) will lead to peri-implantitis.



Management includes patient motivation to oral

hygiene procedure and regular follow up.

OSTEOPOROSIS


It is age – related disorder characterized by

decreased bone mass and susceptibility to fracture.


Placement of implant in patient with osteoporosis

will significantly effect the success rate.


Implant design should be greater in width and

coated with HA to increase bone contact.

SURGICAL COMPLICATION


HEMORRHAGE
Bleeding may result from
Soft dissection

Intraosseous surgery

Managed by applying

Managed by forcing

pressure for 5-10mins

sterile bone wax into
bleeding site.



Placement of implant itself in the final prepared

osteotomy ceases bleeding .



Perforation on the lingual aspect of the alveolar

process in the distal segment of the jaw causes lingual
artery injury.


This may lead to life

threatening

obstruction.


airway

INFERIOR ALVEOLAR NERVE INJURY


When an instrument or the implant contacts the

nerve, the patient experiences a pain sensation even
under anesthesia.


Implant installation should postponed and a

shorter implant should be placed at a later date.


LINGUAL NERVE INJURY


Damage to the lingual nerve leads to loss of

sensitivity in the anterior two thirds of the tongue.


This can be prevented by avoiding any type of

release incision in the lingual direction.


Incisions must always be crestal, with vestibular

release incisions.


Flaps on the lingual side must be elevated

carefully, in tight contact with the bone.

OPENING THE NASAL OR MAXILLARY SINUSES


After completion of implant bed preparation the

bed should be carefully probed, to identify any possible
perforation.


If an oro-antral or an oro-nasal tract is

detected radiographs must be taken immediately.


If perforation is minor, a shorter implant is

placed and the patient is completely informed.


Antibiotic coverage prescribed.

BROKEN BUR


Occurs when the bur gets bind to the bone and

an effort is made to remove it by wriggling the
handpiece shank.


Prevention  grasp the handpiece beneath its

head at the point of bur emission with the thumb and
fore finger and press the fingers together.


The bur is pinched between its head and the

bone, and forced it vertically upward and out of the
bone in a non-torque influenced movement.



If broken bur occur  radiograph taken



Usually broken bur is deep in the osteotomy



Patient informed



Aggressive attempts to remove the bur should
be avoided



If bur is not in a critical location it is best to
leave it untouched.


OVERSIZED OSTEOTOMY
Cause


Lack of experience

Prevention


Bone tapping and implant seating  ultra low

speed handpiece


Using a mark on the rotary instrument to dictate

the exact moment to reverse the motor direction.


Safer approach – stop the motor at a point four

to five rotations from final seating and complete the
procedure with thewww.indiandentalacademy.com wrench.
hand held ratchet

Treatment


Large diameter implant



If osteotomy becomes oversized, for an implant

system where there is no larger diameter implants
then remove the implant and place some particulate
hydroxyapatite graft material and then place the
implant.

FETAL AIR EMBOLISM
Cause


Injection of a mixture of air and water through

the hollow dental drill directly into the mandible, into
the facial and pterygoid plexus veins, and hence the
superior vena cava and right atrium.


Death occur from improper use of a cooling

spray of compressed air and water for apical internal
irrigation.

Prevention


High speed turbine drill with lateral escape

route


Suction placed closed to the cutter creates a

negative local pressure that eliminates any risk of air
embolism.


ACCIDENTAL SWALLOWING


Many implant components are small, when coated

with

saliva

escape

clinicians

grip

and

fall

into

oropharynx.


If this occurs, patient should be placed

immediately with head down position to recover the
lost component.


If this proves impossible, transported with head

low position to the hospital for endoscopic examination.

Prevention


Use

of

manual

screw

drivers

and

similar

instruments equipped with safety wire of dental floss
(min.10cm long)
Correction


Specially trained medical team needed for non-

invasive endoscopic removal of large components.


Very small components – High fiber diet for

patient.

FRACTURED CORTICAL PLATES


Cause – misdirection of a drill



Presence of an unexpected anatomic irregularity



If periosteum is attached to cortical plate- good

prognosis.


If the fragment becomes detached, it can be

wedged back into position, but the prognosis is
guarded.


MANDIBLE FRACTURE


Manson et al 1990 – said that fracture of

mandible in connection with the placement of dental
implants is relatively rare.
Fracture can occur
During bone
site preparation

Excessive stress
during mouth opening

Factors responsible for fracture
Atrophic thin mandible

Multiple implant placements

Increased vulnerable

Mechanical strength is

To thermal injury

Decreased


Prevention
Limited stress to jaw during healing period
Avoid over tightening of screws
Do not use wide diameter implants with large
threads
Management

Immediate implant retrieval from fractured
bone

Rigid connection of osseointegrated implants
with rigid external fixation in order to obtain
immediate stability.

Soft diet for 45 days





POSTOPERATIVE COMPLICATION


HEMATOMA
Prevented by



Proper intraoperative hemorrhage control
Careful post operative compression of the

mucosa flaps covering the implants


Immediate application of cold
packs



In case of extensive hematoma – antibiotics are

prescribed to prevent secondary infection.

INCISION LINE OPENING


It

is

the

most

common

post

operative

complication

If the design of the removable interim
prosthesis is involved, it is corrected

The patient is instructed to rinse 2-3 times daily
with chlorhexidine and gently debride the incision line
with a soft brush

Within few days to weeks the soft tissue will
granulate into the opening.

Resuturing is contraindicated.

CHRONIC PAIN


Implant placed close to mandibular canal may

cause irritation of the inferior alveolar nerve



Such patients may experience chronic pain
Even in the advanced stages of peri-implantitis,

the inferior alveolar nerve may become effected.


Antibiotics are prescribed followed by removal

of the implant as soon as the acute symptoms subside.

RADIOLUCENCIES


If, at 4 or 8 weeks postoperative examination,

the

radiographs

shows

periimplant

osseointegration will not occur.


The patient is informed and
the implant is removed.


lucency,

INFECTION


Characterized clinically by
-

Pain

-

Swelling

-

Suppurative exudate from the wound



1 or 2 sutures are removed for drainage of pus



If the patient experiences fever, an antibiotic

regimen is indicated.

IMPLANT EXPOSURE


Cause
-

Suturing the flaps under tension

-

Pressure from soft tissue borne
prosthesis



The wound is left open



The denture is modified so as no to exert force

on the area of implant exposure.



Patient is instructed to use dry cotton – tipped

applicator to keep it free of material alba.

IMPLANT MOBILITY
Due to
Bone necrosis
Implant movement
Infection

Patient should be informed about the situation
and the implant should be removed to prevent further
damage.
Infection
(+)
(-)
Implant installation is
Larger diameter implant
postponed
placed



LACK OF OSSEOINTEGRATION


Osseointegration

is

a

contact

established

between normal and remodeled bone and an implant
surface without the interposition of non bone or
connective tissue.

Three are two ways of implant retention (de
Putter et al 1985).
Mechanical

Bioactive

Metallic substrate system

HA

Causes (Meffert)


Premature loading, earlier than initial healing

phase


Apical migration of junctional epithelium



Placing the implant with too much pressure



Over heating the bone during site preparation



Implant not fitting the site exactly.

Carlsson et al created bone to implant gap of
0mm, 0.35mm, and 0.85mm respectively in rabbit
tabiae. Those with a gap of 0mm had direct bone to
implant contact.

A 0.35mm gap resulted in few areas

of direct bone to implant contact and 0.85mm gap
resulted in no direct bone to implant contact, indicating
the need for close approximation between bone and
implant for rigid fixation.

PROSTHETIC COMPLICATION


CRITERIA FOR IMPLANT SUCCESS
(Smith & Zarb)


Individual unattached implant should be immobile



No evidence of peri-implant radiolucency



Mean vertical bone loss less than 0.2mm annually

after the first year of function or service.

No persistent pain, discomfort, or infection
attributable to the implant

There is an 85% success rate at the end of a 5
year postrestorative period, with an 80% success rate
at the end of 10 years postrestorative or function.

SCREW LOOSENING AND FRACTURE


More common in maxilla 50% than mandible 20%

Causes


Inadequate torque application



Inaccurate framework abutment interface



Arch form



Cantilever extension

INADEQUATE TORQUE APPLICATION


Recommended torque for prosthetic gold screws

is 10 Ncm and for abutment screw is 20 Ncm



A manual torque converter is available to adjust

torque between 10 Ncm and 20 Ncm.


It is recommended that all screws be tightened

with a torque driver.




Patients are advised at the prosthetic delivery

appointment and during hygiene recall appointments to
monitor for prosthesis loosening.


If movement is present, saliva can be seen

percolating at the interface


The prosthesis is removed and all components

are examined.


If any of the screws are loose, they are

replaced.

ARCH FORM


When an arch form is maintained a tripod effect

lessens bonding moments transmitted to the screw
joint.



The destructive forces cause loosening of

prosthetic and abutment screws as well as fracture of
the screws.

Groove

Turn the Screw

Screw Removed

CANTILEVER EXTENSION

The cantilevered distance beyond the distal
implant determines the lever arm length and the
amount of force that is transmitted to the implants,
framework and component.

For mandible 15mm or less

For maxilla 10mm or less

Factors
Arch form
Bone quality
Parafunctional habits

Over extension of the cantilever may lead to
Screw loosening
or Fracture

Prosthesis
loosening

Implant loss

INACCURATE FRAMEWORK ABUTMENT
INTERFACE


An ideal framework abutment connection is one

that has circumferential contact and is without an
opening at the interface.


A non passive fit will create stresses in the

screws and on the implant
Screw loosening and lack of osseointegration

When evaluating the fit, screws should
tightened one at a time while observing the lift of
frame and the open interfaces.

Torquing all screw before evaluating
interface may bend the framework giving
appearance of accuracy.


be
the
the
the

If these frames are allowed to seat will cause
constant stress on the implant and the component.



IMPLANT FRACTURE


Fractures occurs due to
Fatigue



Trauma

The most frequent area of fracture is just

below the abutment level.





Treatment includes removal of the fragments
Usually apical portion of the implants is

osseointegrated and should be left behind, if not to be
replaced, to prevent further osseous loss (Maeglin
1988)


ESTHETIC COMPLICATION


It is a major problem in maxillary anteriors due
to
-



Labial inclination of implants
Gingival recession

Implant inclination can be corrected using angled

abutments upto 30°


Gingival recession requires mucogingival surgery

for correction.



Gingival margin, normally follows crestal bony

margins.


Gingival recession often occurs if the facial

plates of the bone is lost or if it is extremely thin
following implant insertion.


FRAMEWORK FRACTURE
A



cross

sectional

dimension

of

at

4mmx6mm is needed.


Common areas of framework fracture are :
-

Solder joints

-

Distal to the distal most implant


least



Zarb et al 1990 – reported an increased

incidence of framework breakage if extensions in the
mandible exceed 20mm.


The

fractured

solder

joint

is

reindexed

intraorally and then soldered.


The heat of soldering will destroy any acrylic

veneering material, which is replaced after the
framework fit has been verified after soldering.

UNFAVOURABLE IMPLANT LOCATION AND AXIS
ORIENTATION

Esthetics, phonetics, hygiene and prosthetic
design may be compromised by poor implant position.

In extreme situations, implants may be so poorly
positioned that it is impossible to include them in the
treatment plan.




Block et al 1990 – demonstrated that implants

with an axis orientation angle of greater than 30° were
more likely to be associated with peri-implant bony
defects.


17° or 30° of angulation can be corrected by

placing angulated abutments.




Ailing Implants



Failing Implants



Failed Implants


AILING IMPLANTS


It is least seriously affected of the three

pathologic states.

Exhibits soft

tissue

problems

mucositis.
 Have a favourable prognosis.


(Peri-implant

FAILING IMPLANTS


Shows evidence of
-

Bleeding upon probing

-

Purulence



Pocketing

Progressive bone loss

Have a poorer prognosis when compared with

Ailing Implants


If properly treated, a failing implant may be

saved.

FAILED IMPLANTS


Horizontal mobility beyond 0.5mm



Rapid progressive bone loss



Pain during percussion or function



Continued uncontrolled exudate



Generalized radiolucency around an implant



More than one half of the surrounding bone lost
around an implant



Implant inserted in poor position making them
useless for prosthetic support. (Sleepers)

MAINTENANCE GUIDELINES


The long term success of the dental implant lies

to a great

extent, in the ability of the patient to

control daily plaque.


A twice daily for 30 sec. Chlorhexidine rinse is

recommended for at least 1 week after stage 2
surgery.


A soft tooth brush or

flat end-tuft brush is used in
addition to rinsing. www.indiandentalacademy.com



Plastic sealers are used to remove calculus



Metal instruments, including ultrasonic scalers,

are not recommended.
Rough surface
Plaque accumulation



After removal of hard deposits the prosthesis

and abutments are selectively polished with a

Rubber cup


Flossing cord

Aluminum oxide polishing paste is recommended

to avoid scratching of the titanium abutments and
prosthetic suprastructure.

MAINTENANCE INTERVALS

Appropriate recall intervals are determined on
an individual basis, taking into consideration the
patient’s history and present evaluation.

At prosthesis delivery
Oral hygiene instruction given

One month after prosthesis delivery
Review of home care techniques
Calculus removal and coronal polish

Three months later
Examination of tissues
Calculus removal and coronal polish
Establishment of a recall interval between
3 & 6 months

CONCLUSION
There are three most basic principles for
implant therapy.

Do not harm

Evaluate risks and benefits

Avoid over treatment

One should not have heroic effect

Implant therapy should only be provided when all
of the pre requisites for success are present and when
the patient can be better served by means of implant
prosthesis treatment than by conventional prosthetic
replacement.



BIBLIOGRAPHY


The Branemark implant system – John Beumer
(III)



Implant prosthodontics - Stevens



Implant dentistry – Carl E.Misch



Atlas of oral implantology – A Norman Cranin



Implantology - Hubertus Spiekermann



Implants and restorative dentistry – Carl E.

Misch


Clinical Periodontology – Carranza

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