DIAGNOSIS AND TREATMENT PLANNING FOR
REMOVABLE PARTIAL DENTURES
1) The restoration of partially edentulous mouth presents the
challenge to re-establish masticatory efficiency, esthetics and
comfort in a manner which will promote and perpetuate oral
2) As the remaining teeth and edentulous ridges have to sustain
greater stress than that intended by nature, the preservation of
these tissues is one of the permanent objectives.
3) Many of the dentures which are planned to give lengthy service
become temporary appliances because important biomechanical
factors were ignored during planning.
4) If the relationship between the biologic behaviour of the oral
structures and the mechanical influence of the denture is not
recognized, the denture often contribute towards rapid
disintegration of tissues.
5) A successful partial denture cannot be produced by the skillful
application of technique alone. It must be conceived and
constructed upon the knowledge of oral and dental anatomy,
biology, histology, pathology, physics and their allied sciences if
the oral tissues are to be preserved.
6) Before any rehabilitation procedures are attempted, pertinent
information must be gathered to provide the evidence necessary
to arrive at an accurate diagnosis and develop a round treatment
OBJECTIVES OF PROSTHODONTIC TREATMENT
i) Elimination of disease
Patients who seek treatment are only concerned with replacement
of missing teeth. The dentists primary obligation to the patient is to
emphasize the importance of restoring the mouth to a total state of
The extent to which lost function can be restored depends on
tissue tolerance of the individual, as influenced by age, general health
and health of oral tissues.
In order to fulfill these objectives, the diagnosis and treatment
planning should follow a particular sequence.
It should be complete and include,
- Visual and digital examination of teeth and surrounding tissues.
- Examination with mouth mirror, explorer and a periodontal
- A complete intraoral roentgenographic survey.
- Vitality test of critical teeth.
- Examination of casts correctly oriented on an adjustable
Sequence of oral examination
1. Visual examination: It will reveal many of the signs of dental
disease, consideration of caries susceptibility is of primary
importance. The number of restored teeth present, signs of
recurrent caries and evidence of decalcification should be noted.
Only those patients who demonstrate good oral hygiene and low
caries susceptibility may be considered as good risks for partial
denture treatment. Otherwise prophylactic measures such as
crowning of abutment teeth have to be though of evidence of
periodontal disease, inflammation of gingival areas and degree of
gingival recession should be observed. Depths of periodontal
pockets should be determined and teeth mobility by digital
One should keep in mind that the extent of damage to the
supporting structures by periodontal disease can exactly be
determined only by roentgenographic interpretation.
The number of teeth remaining, the location of edentulous areas
and the quality of residual ridge will have a definite bearing on the
proportionate amount of support that the partial denture will receive
from teeth and edentulous areas.
Palpation can indicate the nature of supporting bone that has been
resorbed and replaced by displaceable fibrous connective tissue. This
is common in maxillary tuberosity regions. Removable partial
dentures cannot be supported adequately by tissue that are easily
displaced. These tissues must be treated non surgically or surgically.
The presence of tori or other exostoses must be detected. The
difference in displaceability of soft tissues covering midpalatal
raphae and soft tissues covering residual ridges must be determined.
If not it will lead to a rocking, unstable uncomfortable denture.
Adequate relief of palatal major connectors must be planned.
2. Relief of pain and discomfort and placement of temporary
It is advisable not only to relieve discomfort arising from tooth
defects but also to determine as early as possible the extent of caries
and to arrest further caries activity until definite treatment can be
instituted. By restoring tooth contours with temporary restorations,
the impression will not be torn on removal from the mouth and a
more accurate diagnostic cast may be obtained.
3. Complete intraoral roentgenographic survey
The objectives of roentgenographic examinations are:
a) To locate areas of infection and other pathoses.
4. A thorough and complete oral prophylaxis
An adequate examination can be accomplished best with the teeth
free of accumulated calculus and debris. Accurate diagnostic casts
can also be obtained only if the teeth are clean.
Cursory examination may precede an oral prophylaxis, but a
complete oral examination should be deferred until the teeth have
been thoroughly cleaned.
5. Exploration of teeth and investing structures
They are explored by instruments and digital examination.
Occlusal relationships and tooth mobility have to be determined. A
situation that looks simple when the teeth are apart may be
complicated when the teeth are in occlusion. E.g.: extrusion of a
tooth or teeth into an opposing edentulous area may complicate the
replacement of teeth in the edentulous area or it may create cuspal
interference. History and diagnostic charts should be filled out at this
6. Vitality tests of remaining teeth
It should be carried out particularly on teeth to be used as
abutments and on those having deep restorations or deep carious
lesions. This may be done either by thermal or electrical means.
It should be an accurate reproduction of the teeth and adjacent
The impression for the diagnostic cast is usually made with an
irreversible hydrocolloid in a perforated impression tray.
The diagnostic cast should be made of dental stone because of its
strength and the fact that it is less easily abraded than dental plaster.
Mounting Diagnostic Casts
Although some diagnostic casts may be occluded by hard,
occlusal analysis is much better accomplished when casts are mounted
on a semiadjustable or adjustable articulator.
The casts have to be mounted in relation to the axis orbital plane
to interpret plane of occlusion in relation to horizontal plane. The
facebow is a relatively simple device used for orienting the maxilla. The
addition of an adjustable infraorbital pointer on the facebow and the
addition of an orbital plane indicator to the articulator makes possible
the transfer of cast in relation to axis orbital plane. This permits to orient
the maxillary cast on the articulator in the same comfortable relationship
of the maxilla to the Frankfort plane on the patient.
A facebow used to transfer the arbitrary hinge axis is termed the
arbitrary face bow and the one used to transfer true hinge axis is termed
kinematic face bow.
An occlusal rim has to be used in face-bow transfer procedures
involving Class I and II partially edentulous situations.
Jaw relationship records for diagnostic casts
One of the first critical decisions to be made in a removable
partial denture service involves the selection of horizontal jaw
relationship (centric relation or maximum intercuspal position). All
mouth preparation procedures depend on this relationship.
If most natural posterior teeth remain and there is no evidence of
TMJ disturbances, neuromuscular dysfunction or deflective occlusal
contacts, the proposed restoration may safely be fabricated with
maximum intercuspation of remaining teeth.
When most of the natural centric stops (posterior teeth) are
missing, the restoration should be fabricated so that maximum
intercuspal position is in harmony with centric relation.
The centric relation position is recorded by the use of an
interocclusal medium without bringing the teeth into contact. Tooth
contact is not allowed because malaligned teeth or interfering cusps tend
to guide the mandible out of centric relation, displacing the heads of the
condyles from their proper positions in the glenoid fossae.
Purposes of diagnostic casts
1. They are used to supplement oral examination by permitting a
view of the occlusion from lingual as well as buccal aspect. The
degree of overclosure, the amount of interocclusal space needed
and the possibilities of interference to location of rests may also
be noted sometimes, the mandibular anterior teeth are on a higher
plane compared to mandibular posterior teeth. This is a disturbing
condition and a destructive process is unavoidable with
advancing age. In some caries, an increase in vertical height of
lower posterior teeth can be induced by placing an occlusal splint
in the palate with occlusal contact available only in the anterior
area. Good results are obtained by constantly wearing such an
appliance over a limited period of time. These patients must be
followed carefully to establish the correct intercuspation of
2. Harmonious occlusal plane and curve of spee
The loss of one or more teeth without immediate
replacement results in loss of contact between the approximating
teeth within the arch and an elongation of teeth in the opposing
arch. Treatment planning in such cases is complicated by a lack
of harmony of the curve of spee and occlusal plane with the path
of movement of the TMJ. The path of movement of the condyle
is fixed whereas the cusp rise in the anterior part of the segment
can be reconstructed by the dentist to aid in establishing a
harmonious intercuspation of the posterior teeth.
The procedure is to have the study casts mounted on an
adjustable articulator with correct condylar settings for both
centric and eccentric functional positions. Then with inlay wax,
build the teeth of the study casts to the contour that will produce
balanced occlusion throughout functional excursions. The dentist
can then determine the teeth that will need a decrease or an
increase in vertical dimension and cusp rise necessary to create a
curve of spee and a plane of occlusion for posterior quadrants.
3. Diagnostic casts permit a topographic survey of the dental arch
that is to be restored by means of a removable partial denture.
The cast in question may be surveyed to determine the
parallelism or lack of parallelism of tooth surfaces involved to
establish their influence on the design of the partial denture.
The need to study parallelism of tooth and tissue surface of
each dental arch is to determine.
a) Proximal tooth surfaces which can be made parallel to
serve as guiding planes.
b) Retentive and non-retentive areas of abutment teeth.
c) Areas of interference to placement and removal from such
a survey a path of placement may be selected that will
satisfy the requirements of parallelism and retention to the
best mechanical, functional and esthetic advantage.
4. Diagnostic casts can be used to make the patient understand
regarding the present and future restorative needs. Occluded or
individual diagnostic casts can be used to point out:
a) Evidence of tooth migration, b) effects of further tooth
migration, c) Hazards of traumatic occlusal contacts.
5. Diagnostic casts may be used as a constant reference as the work
progress. Penicilled marks indicating the type of restorations.
The areas of tooth surfaces to be modified, the location of rests
and the design of partial denture framework, as well as path of
placement and removal, all may be recorded on the diagnostic cast.
6. Individual impression trays may be fabricated on diagnostic casts
for making final impression. This is fabricated on the duplicate
diagnostic cast after wax blockout.
INTERPRETATION OF EXAMINATION DATA
Radiographic interpretation most pertinent to partial denture
construction are those relative to prognosis of remaining teeth that may
be used as abutments.
The quality of the alveolar support of an abutment tooth is of
prime importance because the tooth will have to withstand greater stress
loads when supporting a dental prosthesis, especially greater horizontal
forces. Abutment teeth adjacent to distal extension bases are subjected
not only to vertical and horizontal forces but to torque as well.
Value of interpreting bone density
The quality and quantity of bone in any part of the body is often
evaluated by roentgenographic means.
It is essential to emphasize that changes in bone calcification upto
25-30% cannot be recognized by ordinary roentgenographic means. So
the dentist should realize that roentgenographic evidence shows the
results of changes that have taken place and may not necessarily
represent the present condition.
Normally the interradicular trabecular spaces usually tend to
decrease in size as the examination of bone is proceeded from root apex
towards coronal portion. The normal interproximal crest is ordinarily
shown by a thin white line crossing from lamina dura of one tooth to the
Normal bone usually responds favourably to ordinary stresses.
Abnormal stresses may create a reduction in the size of the trabecular
pattern particularly in that area of bone directly adjacent to the lamina
dura of affected tooth. This decrease in size of the trabecular pattern is
regarded as bone-condensation which is an improvement in bone
An increased thickness of periodontal space ordinarily suggests
varying degrees of tooth mobility. Such teeth have to be evaluated
clinically. X-ray evidence plus clinical findings may suggest the
inadvisability of using such a tooth as an abutment. Rounding off of the
intercrestal bone is the first evidence of periodontal disease. The level of
the bony crest is considered normal when it is within 1.5mm from the
CEJ of the adjacent teeth.
Teeth that have been subjected to abnormal bonding because of
loss of adjacent teeth or teeth that have withstand tipping forces in
addition to occlusal loading may be better risks as abutment teeth than
those that have not been called on to carry an extra occlusal load. If
occlusal harmony can be improved and unfavourable forces minimized
such teeth may be expected to support the prosthesis without difficulty.
The reaction of bone to additional stresses may be positive or negative.
A positive response is indicated by a heavy trabecular pattern and dense
lamina dura. Negative response is the reverse.
Root morphology: Morphologic characteristics of the roots determine to
a great extent to ability of the abutment teeth to resist successfully
additional rotational forces that may be placed on them. Teeth with
multiple and divergent roots will resist stresses better than teeth with
fused and conical roots since the resultant forces are distributed through
a greater number of periodontal fibres to a larger amount of supporting
One must evaluate the condition of the gingiva, looking for
adequate zones of attached gingiva as well as presence or absence of
pockets. If mucogingival involvements, osseous defects or mobility
patterns are recorded, the causes and potential treatment must be
Oral hygiene habits: Efforts must be made to educate the patient relative
to plaque control. The patient must be advised of importance of regular
maintenance appointments after reconstruction.
Caries activity: The past and present caries activity must be determined
and need for protective restorations may be considered. The decision to
use full coverage is based on the age of the patient, evidence of caries
activity and patient’s oral hygiene habits.
High and frequent consumption of sugars can lead to root caries, caries
around restorations or clasps of partial dentures. Excellent protection
from caries can be provided by fluoride applications.
Need for surgery or extractions: Grossly displaceable soft tissues
covering basal seat and hyperplastic tissues should be removed to
provide a firm denture foundation. Mandibular tori should be removed if
they will interfere with optimum location of lingual bar connector or a
favourable path of placement. Extraction of teeth may be indicated for
one of the following reasons.
1) If the tooth cannot be restored to a state of health.
2) Teeth in extreme malposition may be removed. An exception to
the removal of a malposed tooth would be when a distal
extension basal have to be made rather than a more desirable
tooth supported base. If alveolar support is adequate, a posterior
tooth should be retained.
3) A tooth should be extracted if it is unesthetically located and if
the extraction of the same would improve appearance.
DIFFERENTIAL DIAGNOSIS : FIXED OR REMOVABLE
Indications for fixed restorations
1) Tooth bound edentulous regions: Any edentulous space (short
span) bounded by teeth suitable for use as abutments should be
restored with a fixed partial denture.
2) Additional modification spaces in Class III modification 1
A removable partial denture is better supported and stabilized
when a modification area on the opposite side of the arch is present such
an edentulous area need not be restored by a fixed dentures. Additional
modification spaces particularly those involving single missing teeth are
better restored separately by means of fixed dentures. By doing so the
denture is made less complicated by not having to include other
abutment teeth for support and retention. The teeter-tetter effect of the
denture is also avoided.
When an edentulous space exists anterior to a bone-standing
abutment tooth, this tooth is subjected to trauma by movements of distal
extension partial denture far in excess of its ability to withstand such
stresses. The splinting of the line abutment to the nearest tooth is
mandatory. Splinting is best accomplished in such a situation by means
of a fixed partial denture uniting two teeth on either side of the
edentulous space. The abutment crowns should be contoured for
retention and support of the partial denture.
Indications for removable partial dentures
Although a removable partial denture should be considered only
when a fixed restoration is contraindicated, there are several specific
indications for the use of a removable restoration.
1) Long span: A long edentulous span would have abutment teeth
which cannot bear the trauma of horizontal and diagonal occlusal
forces. Also because of ridge resorption, the pontics may have to
be placed in extreme labial inclination for lip support. In such
cases a removable partial denture which provides favourable
esthetics and cross arch stabilization is indicated.
2) Need for effect of bilateral stabilization: In a mouth weakened by
periodontal disease, a fixed restoration may jeopardize the future
of involved abutment teeth. The removable partial denture on the
other hand may act as a periodontal splint through its effective
cross-arch stabilization of teeth weakened by periodontal disease.
3) Excessive loss of bone in posterior area: The pontic of a fixed
partial denture must be related to the residual ridge in such a
manner that the occlusal contact with the mucosa is gentle.
Whenever excessive resorption has occurred, teeth supported by a
denture base may be arranged in a more acceptable bucco-lingual
position than is possible with a fixed partial denture.
4) Where a future change in denture design is anticipated: If the
prognosis of an abutment tooth is questionable or if it becomes
unfavourable while under treatment. It might be possible to
compensate for its impending loss by a change in denture design.
5) Distal extension caries.
CHOICE BETWEEN COMPLETE DENTURE AND
REMOVABLE PARTIAL DENTURE
The loss of remaining teeth can be terrible psychologic shock to
patients. The dentist should explore every possibility of saving them.
1) In most instances it may be more desirable for the patient to
retain loose or broken teeth. In other patients it may be that their
health can be improved if remaining teeth are removed.
2) The age of the patient can be a factor. If the patient is young and
bone is not fully calcified, the remaining teeth should probably be
3) Limitations of maxillary removable partial denture : when
adequate interridge space and sufficient number of healthy
natural teeth are available in strategic-locations, the prognosis for
a removable partial denture is highly favourable. These
conditions are not always present.
Interridge space is reduced by mandibular teeth which
have extended above the plane of occlusion.
An increase in vertical dimension is not possible as it has
not been altered.
If the remaining maxillary teeth are extracted,
biomechanical problem is created by distal extension bases. Gravity
magnified by leverage becomes a major antiretentive factor.
The crown contours of max canines do not provide
undercuts for clasp retention and lingual surfaces are not suitable for
rest preparation, space for rest on lingual surface is lacking because
of opposing mandibular teeth (deep bite).
Crowning of the tooth to create a usable retentive undercut
and to provide cingulum rest requires a labial veneer for cosmatic
reasons (Adds to the cost of restorations).
If maxillary canines must be used as abutments, a clasp
arm and denture flange are often prominently displayed at the corner
of the mouth.
MAXILLARY COMPLETE DENTURES have many advantages
over removable partial dentures in such a situation.
Centric occlusion and centric relation can be made to
coincide at proper vertical relation.
A deep vertical overlap of anterior teeth can be reduced
and a horizontal overlap modified.
Unesthetic appearance of clasp arms and denture flanges
can be avoided.
Need to grind natural teeth to create rest seats is
Thus prognosis is improved for all remaining teeth and