Treatment planning and diagnosis /fixed orthodontics courses

TREATMENT
PLANNING AND
DIAGNOSIS FOR
FIXED PARTIAL
DENTURE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com
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FOR SINGLE TOOTH RESTORATIONS
Introduction
By using cast metal, ceramic and metal ceramic
restorations, large areas of missing coronal tooth structure can
be replaced while that which remains is preserved and
protected. Function can be restored and where required, a
pleasing esthetic effect can be achieved. The successful use of
these restorations is based on thoughtful treatment plan.
In what circumstances should cemented restorations
made from cast metal or ceramic be used instead of amalgam
or composite restorations?

The selection of material and design of the
restoration is based on several factors:
1. Destruction of tooth structure
2. Esthetics
3. Plaque control
4. Financial considerations
5. Retention

1. Destruction of tooth structure
If the amount of destruction previously suffered by the
tooth to be restored is such that the remaining tooth structure
must gain strength and protection from the restoration, cast
metal or ceramic is indicated over amalgam or composite resin.
2. Esthetics
If the tooth to be restored with a cemented restoration is
in a highly visible area or if the patient is highly critical the
cosmetic effect of the restoration must be considered.
3. Plaque control
The use of cemented restorations demands the
institution and maintenance of a good plaque control program to
increase the chances for success of the restoration. The patient
must be motivated to follow a regime of brushing, flossing and
dietary regulation to control or eliminate the disease process
responsible for destruction of tooth structure.www.indiandentalacademy.comwww.indiandentalacademy.com

4. Financial considerations
Finances are a factor in all treatment plans, because
someone must pay for the treatment. If the patient is to pay,
give your best advice and then allow the patient to make the
choice. On one hand, you should not pre-empt the choice by
selecting a less than optimum restoration just because you
think that the patient cannot afford the preferred treatment.
On the other hand, you also should be sensitive enough to
the individual patients situation to offer a sound alternative to
the preferred treatment plan and not apply pressure.

5. Retention
Full veneer crowns are unquestionably the most
retentive. However, maximum retention is not nearly as
important for single tooth restorations as it is for fixed partial
denture retainers. It does become a special concern for short
teeth and removable partial denture abutments. The
cemented restoration made of cast metal, metal and ceramic
or ceramic material alone is fabricated away from the
operatory and is luted in or on the patients tooth at a
subsequent appointment. One type can be better suited for a
particular application than the other or their suitabilities may
overlap.

Restoration longevity
Every dentist would like to be able to answer the
patient’s question, “HOW LONG WILL MY RESTORATION
LAST?”. Logical though the question may be, unfortunately it is
impossible to answer directly. Clinical studies of restoration
longevity have produced widely desperate figures. As a
general rule, cast restorations will survive in the mouth longer
than amalgam restorations, which in turn will last longer than
composite resin restorations. The question of longevity is an
important one to consider when deciding on treatment for a
patient. The more destructive the preparation required for the
restoration the greater the potential risk for the tooth, and
ultimately the greater expense.

TREATMENT PLANNING FOR THE REPLACEMENT OF
MISSING TEETH
The need for replacing missing teeth for a patient is
obvious to the patient when the edentulous space is in the
anterior segment of the mouth. But it is equally important in
posterior region. It is tempting to think of the dental arch as a
static entity, but that is certainly not the case. It is in a state of
dynamic equilibrium with the teeth supporting each other.
When a tooth is lost, the structural integrity of the dental arch
is disrupted and there is a subsequent realignment of teeth as
near state of equilibrium is achieved. Teeth adjacent to or
opposing the edentulous space frequently move into it.

Selection of the type of prosthesis
Missing teeth may be replaced by one of three
prosthesis types:
1. A removable partial denture
2. A tooth supported fixed partial denture
3. Implant supported fixed partial denture
Several factors must be weighed when choosing the
type of prosthesis to be used in any given situation.
Biomechanical, periodontal, esthetic and financial factors as
well as the patients wishes, are some of the more important
ones. It is not uncommon to combine two types in the same
arch such as a removable partial denture and a tooth
supported fixed partial denture or implant supported and
tooth supported fixed partial denture. In treatment planning
there is one principle that should be kept in mind: treatment
simplification. www.indiandentalacademy.comwww.indiandentalacademy.com

Removable Partial Denture
RPD is generally indicated for edentulous patients greater
than two posterior teeth, anterior spaces greater than four incisors or
spaces that include a canine and two other continuous teeth, that is
central incisor, lateral incisor and canine or lateral incisor, canine and
first premolar or the canine and both premolars. An edentulous space
with no distal abutment will usually require a removable partial
denture. The requirements of an abutment for a RPD are not as
stringent as those for a fixed partial denture abutment. Tipped teeth
adjoining edentulous spaces and prospective abutments with
divergent alignments may lend themselves more readily to utilization
as RPD rather than FPD abutments. Periodontally weakened primary
abutments may serve better in retaining a well designed RPD than in
bearing the load of a FPD. If there has been a severe loss of tissue in
the edentulous ridge, a RPD can more easily be used to restore the
space both functionally and esthetically. For successful RPD
treatment the patient should demonstrate acceptable oral hygiene
and show signs of being a reliable recall candidate.www.indiandentalacademy.comwww.indiandentalacademy.com

Conventional tooth supported fixed partial denture
When a missing tooth is to be replaced a fixed partial
denture is preferred by a majority of the patients. The usual
configuration for a FPD utilizes an abutment tooth on each end
of the edentulous space to support the prosthesis. There
should be no gross soft tissue defect in the edentulous ridge. If
there is it may be possible to augment the ridge with grafts to
enable the construction of a fixed prosthesis. Dry mouth
creates a poor environment for a FPD. The margins of the
retainers will be at a great risk from recurrent caries limiting the
life of the prosthesis.

Resin bonded tooth supported fixed partial denture
The resin bonded fixed partial denture is a conservative
restoration that is reserved for use on defect free abutments in
situations where there is a single missing tooth, usually an
incisor or premolar. A single molar can be replaced by this
type of prosthesis if the patients muscles of mastication are
not too well developed. Thus a assuring that a minimum load
will be placed on the retainers.

Implant supported fixed partial denture
Fixed partial denture supported by implants are ideally
suited for use where there are insufficient numbers of abutment
teeth or inadequate strength in the abutments to support a
conventional FPD, and when patient attitude and / or a
combination of intraoral factors make a removable partial
denture a poor choice. Implant supported FPDs can be
employed in the replacement of teeth when there is o distal
abutment. Span length is limited only by the availability of
alveolar bone with satisfactory density and thickness in a broad
flat ridge configuration that will permit implant placement.

No prosthetic treatment
If a patient presents with a long standing edentulous
space into which there has been little or no drifting or
elongation of the adjacent or opposing teeth, the question of
replacement should be left to the patient’s wishes. If the
patient perceives no functional, occlusal or esthetic
impairment, it would be a dubious service to place a
prosthesis. This in no way contradicts the recommendation
that a missing tooth routinely should e replaced.

ABUTMENT EVALUATION
Whenever possible an abutment should be a vital tooth.
However, a tooth that has been endodontically treated and is
asymptomatic with radiographic evidence of a good seal and
complete obturation of the canal can be used as an
abutment. However, the tooth must have some sound
surviving coronal tooth structure to ensure longevity. The
teeth that have pulp capped in the process of preparing the
tooth, should not be used as a FPD abutment unless they
are endodontically treated. Supporting tissues surrounding
the abutment teeth must be healthy and free from
inflammation before any prosthesis can be contemplated.
Normally abutment teeth should not exhibit mobility since
they will be carrying an extra load.

The roots and their supporting tissues should be evaluated
for three factors:
1. Crown root ratio
2. Root configuration
3. Periodontal ligament area

Crown root ratio
This ratio is a measure of the length of the tooth occlusal
to the alveolar crest of bone compared with the length of root
embedded in the bone. As the level of the alveolar bone moves
apically the lever arm of that portion out of bone increases the
chance for harmful lateral forces is increased. The optimum
crown root ratio for a tooth to be utilized as a FPD abutment is
2:3. A ratio 1:1 is the minimum ratio that is acceptable for a
prospective abutment under normal circumstances.
Root configuration
This is an important point in the assessment of an
abutment’s suitability from a periodontal standpoint. Roots that
are broader labio-lingually than they are mesio-distally are
preferable to roots that are round in cross section. Multi-rooted
posterior teeth with widely separated roots will offer better
periodontal support than roots that converge, fuse or generally
present a conical configuration.www.indiandentalacademy.comwww.indiandentalacademy.com

Periodontal ligament area
Another consideration in the evaluation of prospective
abutment teeth is the root surface area or the area of
periodontal ligament attachment of the root to the bone.
Larger teeth have a greater surface area and are better able
to bear added stress. FPDs with thick short pontic spans
have a better prognosis than do those with excessively long
spans. In a statement designated as by Johnson et al the
root surface area of the abutment teeth had to equal or
surpass that of the teeth being replaced with pontics.

SPECIAL PROBLEMS
Pier abutments
An edentulous space can occur on both sides creating
a lone free standing pier abutment. Physiologic tooth
movement, arch positions of the abutments and a disparity in
the retentive capacity of the retainers can make a rigid five
unit fixed partial denture a less than ideal plan of treatment.

Tilted molars
A common problem that occurs with some frequency is
the mandibular second molar abutment that has tilted
mesially into the space formerly occupied by the first molar. It
is impossible to prepare the abutment teeth for a FPD along
the long axis of the respective teeth and achieve a common
path of insertion. A proximal half crown sometimes can be
used as a retainer on the distal abutment. This preparation
design is simply a three quarter crown that has bee rotated
90 degrees so that the distal surface is uncovered. If there is
a severe marginal ridge height discrepancy between the distal
of the second molar and the mesial of the third molar as a
result of tipping, the proximal half crown is contraindicated. A
telescope crown and coping can also be used as a retainer
on distal abutment. A non rigid connector is another solution
to the problem of the tilted FPD abutment.

Canine replacement FPD
FPDs replacing canines can be difficult because the
canine often lies outside the inter abutment axis. The
prospective abutments are the lateral incisor, usually the
weakest tooth in the entire arch and the first premolar, the
weakest posterior tooth. A FPD replacing a maxillary canine is
subjected to more stresses than that replacing a mandibular
canine since the forces are transmitted outwards (Labially) on
the maxillary arch against the inside of the curve (weakest
point). An edentulous space created by the loss of a canine
and any two contiguous teeth is best restored with a RPD.

Cantilever FPD
A cantilever FPD is one that has an abutment or
abutments at one end only with the other end of the pontic
remaining unattached. This is a potentially destructive design
with the lever arm created by the pontic, and is frequently
misused. A cantilever can be used for replacing a maxillary
lateral incisor. There should be no occlusal contact on the
pontic in either centric or lateral excursions. The canine must
be used as an abutment and it can serve in the role of solo
abutment only if it has a long root and good bone support. A
cantilever can also be used to replace a missing first premolar.
This scheme will work best if occlusal contact is limited to the
distal fossa.

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