Complication & Failure of Implants in prosthodontics

Complications and failures in implant dentistry

1. 1
By
PUSHKAR GUPTAPUSHKAR GUPTA
PG Student,
Dept. of Prosthodontics
IMPLANT FAILURE

2. 2
INTRODUCTION
The use of dental implants has enabled the
fabrication of highly functional and esthetic
restorations and improved the predictability of
treatment. However, at any point during rehabilitation
and maintenance complications and failure can occur.

3. 3
 Improper Patient
Selection
 Surgical complication

Intraoperative Postoperative
complication complication
 Prosthetic
Complication

4. 4
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)

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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.

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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

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In 1988 Misch classified bone density into
D1Dense cortical bone
D2Thick dense to porous cortical bone on crest
and coarse trabecular bone within
D3Thin porous cortical bone on crest and fine
trabecular bone within
D4Fine trabecular bone
D5Immature, nonmineralized bone

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 As the bone density decreases the strength of
the bone also decrease.
 Stress can be reduced by :
A.decreasing the cantilever length
B.Narrowing the occlusal table design.
C.Wider implants
D.HA Coatings
 0.5mm increase in width – 10% - 15% increase in
surface area.

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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.

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 After estimating the available bone height by
panoramic radiograph, the implant is selected
accordingly.

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 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.

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 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 way of reducing
complication and implant failure.

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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.

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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

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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).

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 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.

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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.

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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.

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SURGICAL COMPLICATIONSURGICAL COMPLICATION

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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 .

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 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 airway
obstruction.

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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.
Parasthesia of lip

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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.

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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.

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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.

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 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.

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OVERSIZED OSTEOTOMYOVERSIZED 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 the hand held ratchet wrench.

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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.

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FETAL AIR EMBOLISM 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.

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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.

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ACCIDENTAL SWALLOWING 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.

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Prevention 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.

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FRACTURED CORTICAL PLATES 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.

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MANDIBLE FRACTURE 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 Excessive stress
site preparation during mouth opening

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Factors responsible for fracture
Atrophic thin mandible Multiple implant placements
Increased vulnerable Mechanical strength is
To thermal injury Decreased

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Prevention 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

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POSTOPERATIVE COMPLICATIONPOSTOPERATIVE COMPLICATION

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HEMATOMAHEMATOMA
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.

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INCISION LINE OPENING 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.

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43. 43
CHRONIC PAIN 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.

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RADIOLUCENCIES RADIOLUCENCIES
 If, at 4 or 8 weeks postoperative examination,
the radiographs shows periimplant lucency,
osseointegration will not occur.
 The patient is informed and
the implant is removed.

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INFECTIONINFECTION
 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.

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IMPLANT EXPOSURE 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.

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 Patient is instructed to use dry cotton – tipped
applicator to keep it free of material alba.

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IMPLANT MOBILITY 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

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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

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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.

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PROSTHETIC COMPLICATIONPROSTHETIC COMPLICATION

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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.

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SCREW LOOSENING AND FRACTURE
 More common in maxilla 50% than mandible 20%
Causes
 Inadequate torque application
 Inaccurate framework abutment interface
 Arch form
 Cantilever extension

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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.

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 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.

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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.

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Groove Turn the Screw
Screw Removed

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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 Prosthesis Implant loss
or Fracture loosening

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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

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 When evaluating the fit, screws should be
tightened one at a time while observing the lift of the
frame and the open interfaces.
 Torquing all screw before evaluating the
interface may bend the framework giving the
appearance of accuracy.
 If these frames are allowed to seat will cause
constant stress on the implant and the component.

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IMPLANT FRACTURE
 Fractures occurs due to
Fatigue Trauma
 The most frequent area of fracture is just
below the abutment level.

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 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)

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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.

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 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.

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FRAMEWORK FRACTURE
 A cross sectional dimension of at least
4mmx6mm is needed.
 Common areas of framework fracture are :
- Solder joints
- Distal to the distal most implant

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 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.

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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.

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 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.

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MEFFERT
Ailing Implants
 Failing Implants
 Failed Implants

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AILING IMPLANTS AILING IMPLANTS
 It is least seriously affected of the three
pathologic states.
 Exhibits soft tissue problems (Peri-implant
mucositis.
 Have a favourable prognosis.

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FAILING IMPLANTS FAILING IMPLANTS
 Shows evidence of
- Pocketing
- Bleeding upon probing
- Purulence
- Progressive bone loss
 Have a poorer prognosis when compared with
Ailing Implants
 If properly treated, a failing implant may be
saved.

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FAILED IMPLANTSFAILED 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)

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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.

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 Plastic sealers are used to remove calculus
 Metal instruments, including ultrasonic scalers,
are not recommended.
Rough surface
Plaque accumulation

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 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.

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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

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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.