Rationale for dental implants /certified fixed orthodontic courses by Indian dental academy

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Rationale for dental
implants


Introduction

One of the most significant advances in
restorative dentistry is the replacement of lost
natural teeth by an implant. Two decades ago a
majority of dentists were skeptical about
implants and rejected them. Today's situation is
reversed. Tomorrow implants will be the
workhorse of restorative dental practice.
Today’s journal club is from the British
Dental Journal, vol:2000; no.12, june24, 2006.
This article is the first amongst the 16 articles
which we propose to discuss in the on coming
journal clubs, so as to have a brief & clear
overview of dental implants.

Rationale means “reason” or
“underlying principle”.
This article ‘Rationale for dental
implants’ authored by S.Jivraj & W. Chee,
form the University of Southern California,
School of dentistry, emphasizes the
various factors to prove the superiority of
dental implants over conventional
treatments to replace lost natural teeth.


1.
2.
3.
4.

Implant dentistry has enjoyed great
progressive
development in the
recent years.
The areas
of development can be listed as:
Development of new implant systems
Improved diagnostic procedures
Novel surgical techniques
Introduction of state of art CAD-CAM
technology (to improve prosthodontic precision
of fit & allow restoration of implants in nonideal positions)
Osseointegration is a well predicted
phenomenon with the present day implants.
Successful osseointegration is not a sole
representative of success of an implant.

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The implant is deemed a success when the
definitive restoration restores the patient – Tatum
The normal contour
The normal function
Esthetics
Speech
Health
Clinical success has been obtained with the
use of implant therapy in edentulous & partially
edentulous patients. The implant therapy has
greater advantages over conventional, fixed or
removable treatment options. But many clinicians
still choose to prepare the teeth for an FPD than
to go for implant therapy.

Tooth structure has to be significantly
reduced with FPD’s to obtain esthetics. Such
reduction can predispose to endodontic and
periodontal problems.
The factors which contribute to the need of
implant supported restorations are divided into
four groups.
1.
2.
3.
4.

Preservation of tooth structure
Preservation of bone
Provision of additional support
Resistance to disease

Preservation of tooth structure
Before implant therapy, FPD’s were
considered as the common mode of treatment.
But failures of FPD’s are supported by long term
studies. Studies conducted by Walton TR, has
shown 87% of success of FPD at 10 years &
69% at 15 years. Failures were also due to nonvital anterior abutments, pier abutments and
pulp capped teeth.
Studies compiled by Goodacre from 19811997 on clinical complications of
osseointegrated implants related complications
due to:

Type of prosthesis
 Length of the implant
 Bone quality
 Arch
 Time
When compared to other prosthetic designs
implant single crowns had the lowest failure
rate at 2.7%. The present article concentrates
on the complications related to single tooth
implants omitting the other factors. Most of the
failures of implant supported restorations
occurred during the first year & implant loss
was significantly lower in the second & the third
year.



The restoration that has passed the first
year of service is likely to survive a
considerable length of time.
Studies conducted by Zarb, Hass & Henry
on single unit implant restorations have
demonstrated 96.5% success rate over a
period of 11 years.
There are no reports regarding the loss of
adjacent teeth when single tooth implant
restorations have been undertaken, but this is
not the case with the FPD.

Preservation of bone

o
o
o
o

There exists a close relationship between the
tooth & the bone. A change occurs in the bone if
its function is altered, & to maintain that, bone
requires stimulation.
Pietrokvoski, stated that after tooth loss, lack
of stimulation occurs which causes,
A decrease in bone trabeculae
Decreased bone density
Loss of width
Loss of height

After a 25 year study it was found that a four fold
greater loss was seen in the maxilla than in the
mandible. Bone loss was seen antero-posterioly in the
maxilla & downwards and laterally in the mandible.
This usually results in a class III skeletal
relationship. Due to this, the maxillary molars are more
facially placed & the mandibular molars are more
lingually positioned.
The literature concludes that if the teeth are lost
the bone is not stimulated which results in bone loss.
Usually a partial or complete denture cannot
maintain the bone & may also increase the bone loss
if it is ill – fitting.
These patients must be informed about this during
extraction.

Continued bone loss decrease retention &
stability.
Soft tissue changes like loss of facial
support & VD can affect the overall esthetics.
After a severe bone loss, if the patient
desires implant therapy, surgical procedures
like iliac crest grafting must be performed.

Placement of dental implants stimulates &
preserves bone, thereby maintaining the
function & esthetics.

Provision of additional support
Dental implants provide additional support by
improving the masticatory performance.
Normally a patient who grinds or clenches exerts
up to 1000psi of force. In an edentulous patient
the force is reduced to about 50psi.
Carr & Laney stated that if a patient is
edentulous for a longer time they generate less
force. This state can also affect the overall
health of the patient.

When compared with complete denture prostheses
implant supported fixed prostheses results in
increased bite force similar to that of a fixed
restoration. RPD’s do not provide posterior support,
due to resiliency and like effect, whereas dental
implants provide.
One more advantage of implant supported
restoration is “retrievability”. It is advantageous when
reservicing, replacement or salvaging of an implant is
considered. It is considered as a safety factor during:
 loosening of the retaining screw
 # of porcelain
 # of an abutment and
 Modification of the prostheses through loss of an
implant.

Implant restorations can be:
 Screw retained
 Cement retained
 Combination of both
Screw retained prostheses are easily
retrieved and it is the authors preference
whenever possible.


Resistance to disease
Patients who are susceptible to
disease should be carefully evaluated
before the treatment plan. Elderly patients
are on many drugs which can alter the
salivary flow leading to root surface caries.
In such patients decision must be
made on long term basis whether to
preserve the teeth or use dental implants.

Waerhaug, Wilding & Shugars studied the
various periodontal changes in a partial denture
wearer & concluded that patients wearing RPD
have:
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Greater mobility of the abutment teeth
Greater plaque accumulation
Increased bleeding on probing
More incidence of caries
Accelerated bone loss in the edentulous regions

Dental implants are resistant to disease as
they are not susceptible to dental caries & also
preserve the adjacent teeth.

With the traditional treatment options
available, decision has to be made as to
when extraction & implant placement can
be done which can alter the treatment
planning process.
There are two schools of thought, of
which one implies on a traditional
treatment, whereas the other advocates
extraction of a compromised tooth &
replacing it with an implant in patients who
are prone to caries.

Summary
Completely edentulous & partially edentulous
conditions are treated with complete dentures &
removable partial dentures respectively. The
decreased masticatory efficiency of these
prostheses when compared with that of a natural
dentition is well documented. Furthermore these
prostheses also causes progressive resorption
of bone. The implant supported prostheses
offers predictable solutions than the
conventional prostheses.
“These patients can enjoy a better quality of life”.

In a nut shell…..


Dental implants are a more conservative long
term option than long span bridges



Placement of dental implants serves to preserve
bone



Dental implants can provide long term posterior
support than RPD’s



Dental implants are resistant to disease

Next article
The next article in this series will focus on

treatment planning of implants in
the posterior quadrants.


Rationale for dental implants /certified fixed orthodontic courses by Indian dental academy

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