Removable Partial Denture and its Effects on Periodontal
A partial denture, when properly designed, carefully made,
and serviced when needed, can be an entirely satisfactory
restoration and serve as a means of preserving the remaining
oral structures as well as restoring missing dentition.
A partial denture should be constructed with adequate abutment
support, good periodontal health to the remaining structures,
optimal base support, with harmonious and functional occlusion.
The occlusion on the partial denture should be made to harmonize
with the existing adjusted natural occlusion, and that this
can be accomplished by the registration of functional occlusal
path. Periodic recall of the patient to evaluate the oral
tissues, their response to the restoration, and the restorations
themselves is a part of total treatment responsibility.
Changes in oral structures or the dentures must be ascertained
rather soon to avoid compromised oral health. This can be
accomplished by periodic recall. This paper is dealing with
several issues concerning the practice of removable prosthetics
dentistry, mainly the design and construction of removable
partial denture, and its effect on the periodontal health,
specifically the oral hygiene, the mobility of the remaining
dentition, the gingival index, plaque index, occlusal stability,
and pocket depth.
Glickman in 1948 reported that from the periodontal viewpoint,
fixed prostheses are the restorations of choice for replacement
of missing teeth, but there are some clinical situations
in which removable partial prostheses are the only possible
way to restore the lost function of the dentition. One of
the most common situation is the Kenedy class I and class
II of which there is a bilateral or unilateral edentulous
areas located posterior to the remaining natural teeth.
Patient may not be able to afford implant therapy as the
mean of restorative effort. Several issues must be considered
when constructing a removable prosthesis. One of the most
important is patient oral hygiene. McCracken suggested that
the oral hygiene of the patient must be assessed as an important
step in diagnosis and treatment planing. Seeman in 1963
emphasized the need for establishment of a satisfactory
level of oral hygiene during the treatment planing stage.
The presence of a partial denture may increase plaque formation
around the remaining teeth, so oral hygiene must receive
great emphasis in these patients. It is reasonably fair
to assume that the patient will do little better in the
long term future than he has done in the past. Therefore,
before and after constructing a partial removable prosthesis,
patient must be motivated and maintained his remaining dentition
with good oral hygiene to preserve the integrity of the
Bergman et al in 1977 published a six year follow up study
on 28 patients with removable partial dentures to evaluate
the effect of removable denture and oral hygiene. All patients
were given Oral Hygiene Instructions and periodontal treatment
as needed. The dentures were carefully treated planned and
designed according the case. The follow up period included
yearly visits to clean and adjust the prosthesis. The results
showed that there was little reduction of the periodontal
health, and there were small number of carious lesions reported.
There was a small deterioration of the occlusion, articulation,
stability and clasp retention. These findings are very normal
and seems to be related to the inherent fact of using an
artificial appliance for mastication and function. These
are the main reason for frequent follow up visits for dentures
adjustments. In short the authors state that there is little
evidence to support the idea that partial dentures will
cause various lesions or even periodontal diseases, if with
good prosthetic design and plaque control is achieved.
Stipho et al. investigated the relationship between plaque
accumulation and removable partial denture design. 14 dental
students were included in the study with the prosthesis
design of an acrylic palatal base partial denture which
covered the palatal gingiva on one side and was relieved
on the other side. The plaque from both surfaces was taken.
The results showed both sides collected plaque with a higher
accumulation on the covered palatal side. In short, the
authors suggest that people with less than adequate plaque
control should not have partial dentures. However, if a
prosthesis must be made, the marginal gingiva should be
Addy and Bates in 1977 investigated the effect of partial
denture and chlorhexidine gluconate gel on plaque accumulation
in the absence of oral hygiene on a group of 24 partial
denture wearers. Oral hygiene procedures were withdrawn.
The modifying effect of a 1% chlorhexidine gluconate gel
on this plaque accumulation was measured. Plaque accumulation
was measured at the end of four different denture-wearing
regimens each 3 days in length. The wearing of a partial
denture either day only or day and night, significantly
increased plaque accumulation over not wearing a denture.
There was no significant difference between plaque accumulation
with day wear and day and night wear. The increase in plaque
accumulation with day and night wear resulted from an equal
and significant increase in both buccal and lingual plaque
accumulation. Chlorhexidine gluconate in the form of a gel
significantly reduced plaque accumulation during daytime
wear. These results tend to confirm that plaque control
is a major factor in determining the long-term effects of
partial dentures upon the periodontal structures and emphasize
the importance of oral hygiene in partial denture wearers.
Bergman, Hugoson, and Olsson investigated the periodontal
and prosthetic conditions in patients treated with removable
partial dentures and artificial crowns in a longitudinal
study of 30 patients over two years. All patients were motivated
regarding oral hygiene and received periodontal therapy
to achieve good periodontal and dental health prior to receive
the partial denture. Clinical parameters are the Loe and
Silness’ gingival index, Silness and Loe’s plaque
index, pocket depth, and mobility. Caries also were documented
and prosthetic factors were examined regarding the occlusion,
articulation, and location of crown margin. Finally, resilience
of alveolar process and the mucosal changes also were documented.
Ten other patients with an average of 9.5 residual teeth
per jaw served as the controls, which receive the same kind
of treatment but did not receive the partial denture. The
results were reported for one and two years after delivery
of the RPD. The result indicated that there is no significant
change regarding the gingival index, depth of periodontal
pockets, and plaque index during the two years observation
period. A decrease of mobility of the abutment teeth was
noted between 0 and 2 years. The mobility of the teeth had
not increased during the two years use of partial denture
as suggested in other study. Radiographic assessment of
bone loss revealed a reduction in marginal bone level averaging
1.01 per cent of the bone distal to the abutments; however,
there was no reduction recorded mesially to the abutments.
Reduction was attributed to the direct pressure on the underlying
bone. This support the concept of teeth support prosthesis
is more favorable in term preserving periodontium compare
to tissue supported prosthesis. Location of crown margin
also affects the gingival health. The more subgingival the
margin was placed, the higher the gingival index was noted.
Patient wearing prosthesis did not have an increase in frequency
of caries. Some deteriorations regarding the prosthesis
occlusion, articulation, stability and clasp retention were
noted, which supported the recommendations that patient
with RPD should be regularly followed up. The study concluded
that with a careful planning of the prosthetic treatment
and with an adequate oral and denture hygiene, checked up
at every clinical visit, little, if any, damage will be
caused to the remaining teeth.
Another study by Schweizer investigated the biological effects
regarding mobility of the abutment teeth in splinting teeth
with removable bridges. Fifteen abutment teeth with pathologic
mobility were splinted with removable telescoped bridges.
Mobility was measured at the time the splints were placed
and at 1 and 12 month intervals. The result showed that
daily removal and insertion of splints did not injure tooth
supporting structures and that average tooth mobility did
not increase or decrease during the one year test period.
The design of the partial denture is very critical in maintaining
periodontal health and preserving the stability of the remaining
dentition. To provide maximal stability for removable partial
prostheses, every effort should be made to retain posterior
teeth for the distal support of the edentulous areas. When
posterior teeth cannot be retained to support edentulous
areas, the design for the removable partial prostheses becomes
challenging and the relationship of the framework to the
distal surface of abutment teeth, especially in the case
of bilateral distal extension partial dentures (Kenedy class
I), becomes an area of controversy.
Carlson, et al in 1965 studied the oral and prosthetic conditions
in the use of dentogingivally supported partial dentures.
A longitudinal study of 99 patients was performed. The results
were interesting because they represent the follow-up of
previous studies in which they concluded that indications
of partial dentures should be narrowed considerably due
to the high frequency of local pathologic alterations. Altogether
36% of the follow up patients did not have their original
prosthesis at the time of the five year reevaluation. For
the remaining patients, at follow up there was a high percentage
of loose abutment teeth. 37 patients were assessed as having
acceptable prosthesis based on no clinical or radiographic
signs of pathology. There was a higher occurrence for damage
to tissues to the tissues of the lower prosthesis than the
upper prosthesis. This has to be taken with care because
the design and the areas for support are different, so this
seems to be observational in nature. Most of the denture
users were happy except for trapping food under the denture.
This is to understand but if the patient was trapping food
underneath the denture, then there is high probability that
the denture design was not appropriate In short, the success
for a partial denture depends on both the oral as well as
the design of the partial. This is a classical study, and
very well done. Some of the short comings are that a lot
of patients were not seen at recall due to not having the
baseline prosthesis, and no designs were stated, as well
no standardized radiographs.
Isidor et al evaluated the long term periodontal changes
in 52 patients with moderate to advanced bone loss with
distally extending cantilever bridges or removable partial
dentures. All patients were treated for their periodontal
needs, and 27 patients received distally extended cantilever
bridges, and 25 received distally extending removable partial
in the mandible. PI, GI, PD, and bone level were recorded.
The results demonstrated that at reevaluation visit there
was no difference in the treatment modalities and that patients
can be treated with fixed or removable prostheses. There
was a higher PI with patients who had RPD. The last and
important statement made by the author is that regular visits
and oral hygiene instructions are imperative to success.
This seems to be a very well controlled study, and gives
a more realistic view of some patients in which removable
partial dentures is the only feasible way to restore function.
Benson in 1979 has shown that the I-bar type of removable
partial denture can be utilized by many patients with little
or no detrimental effect on periodontal health. This particular
design utilizes an I-bar infrabulge clasp, mesially positioned
occlusal rests, and metal guide planes. The technique emphasizes
the need for intraoral adjustment of the denture framework
to minimize undue torque on the abutment teeth. This particular
design of removable prostheses has also been shown to provide
more favorable loading of abutment teeth than that seen
with a circumferential clasp design.
Clasp design is very critical since the clasps should be
passive and exert no force on the teeth when the partial
denture is at rest. Improper clasp design will introduce
occlusla trauma to the abutment tooth which the clasp was
provided. Research done by Clayton shows that the use of
an improperly designed suprabulge or circumferential clasp
exerts a great deal of force on the abutment tooth.
Cecconi investigated the effect of four different type of
partial denture clasp design on abutment tooth movement.
The four designs are: 1) a cast bar retentive clasp arm,
cast lingual bracing arm, and distal occlusal rest; 2) a
cast circumferential retentive clasp arm, cast lingual bracing
arm, and a distal occlusal rest; 3) a cast I bar retentive
clasp arm, a distal guide plane, and a mesial occlusal rest;
and 4) an 18 gauge wrought wire retentive clasp arm, cast
lingual bracing clasp arm, and a distal occlusal rest. Movement
of abutment tooth can be observed in four directions: mesial,
buccal, distal, and lingual. The test apparatus consists
of a gauge mounted to the plywood base of which the test
model (with the RPD) was fixed to. Twenty pounds load was
applied in five different directions: vertical, anterior,
posterior, buccal, and lingual. The result indicated that
in regarding to the direction of the movements, the dominant
direction of the movement for the abutment tooth was mesial-buccal
when it was the load side abutment; and mesial-lingual when
the abutment tooth was the non-load side abutment. The direction
of abutment tooth movement was not altered significantly
by clasp design. In regarding to the magnitude of the abutment
movement, casting with I bar as retentive clasp arm exhibit
greater abutment tooth movement than did other clasp assemblies.
The other three designs did not significantly differ as
to their effect on abutment tooth movement.
Bissada et al. investigated the gingival responses to various
types of removable partial dentures. The purpose of this
investigation was to seek a solution to weather the partial
dentures should cover the gingival margin, with or without
relief, or should the free gingival margin be uncovered.
Sixty eight patients were selected on the basis of having
2 or 3 maxillary teeth missing. During the study, 28 metallic
and 40 nonmetallic partial dentures were constructed. There
were three dentogingival relationships as described above.
Clinical and histologic evidence was taken at 1, 6, and
12 months. The results were that the denture made with no
gingival relief had the most associated pathology. In addition
the metallic partial caused less inflammation than the resin
dentures. There were no radiographic changes noted. This
was a very well done study. Most of the basic removable
partial denture concepts are based on the relationship between
the gingival margin and the denture, and this article added
or dictated some of these concepts of denture design. It
had every thing except for a control. The take home message
is that partial must be away from the tissues. The fact
that metallic removable partial dentures elicited less gingival
inflammatory changes needs to be related to the type of
acrylic used and how fast it became porous and trapped plaque.
Other area of partial designes are the occlusal rest and
the use of stress breaker. Occlusal rests should be designed
to direct the forces along the vertical axis of the tooth.
To accomplish this, the rest is seated in a spoon-shaped
preparation in the abutment tooth with the preparation floor
inclined so that the deepest point is toward the vertical
axis of the tooth. This purpose is also accomplished if
occlusal rests are extended beyond the central zone of the
occlusal surface of premolars or if the occlusal surface
overlying one of the roots of the molars is covered. Removable
partial prostheses should always be constructed with occlusal
rests. Rests are sometimes omitted for the ostensible purpose
of reducing axial load on teeth with weakened periodontal
support. Such dentures jeopardize the teeth, because they
settle and cause gingival and periodontal disturbances.
Stress breakers, which connect the retainer and saddle areas
with flexible and movable joints, are sometimes used to
prevent excessive occlusal forces on abutment teeth. However,
comparisons have revealed no advantage of stress breakers
over rigid connectors in this respect. With rigid connectors
between clasps and saddle areas, the resilience of the mucosa
acts as a stress breaker. It permits controlled movement
of the prosthesis so that the tissue-borne sections take
the initial occlusal stress and prevent sudden impact on
the periodontium of the natural teeth.
Rissin et al published an investigation which purpose was
to longitudinally study the response of the periodontal
health related to fixed and removable partial denture abutment
teeth. This study was performed at a VA facility with 1221
subjects that were recalled at three year intervals to access
the purpose of this investigation. The results showed that
there was no difference between the periodontal health of
fixed and removable partial denture abutment teeth. However,
regardless of treatment good home care, and professional
care must be taken. The interesting finding was that replacing
missing teeth reduced mobility in either the fixed or removable
situations. The intentions of this study are good; however,
the designs of either prosthetic devices were not considered
a factor. But we may take from this that even though we
do not know what type of device was used, we can assume
that oral hygiene instructions is a must.
Another issue of partial design is to determine the number
of abutment teeth to be used. Increase periodontal support
can be achieve with higher number of abutment teeth. Multiple
abutments reduce injurious lateral and torsional stresses
on abutment teeth, and their use should be standard procedure
in patients with reduced periodontal support and those who
are to receive removable partial dentures. The clinician
can make multiple abutments by connecting inlays or crowns
or by clasping abutment and adjacent teeth in sequence.
When the terminal tooth is periodontally weak, more than
one adjacent tooth should be used for added support. Joining
a weakened tooth to a strong one is as likely to weaken
the strong tooth as to strengthen the weak one. It is always
advisable to consider whether the long-term interest of
the patient would be better served by extracting the prospective
weak abutment tooth and making a multiple abutment of two
adjacent teeth that are relatively well supported.
One of the concern regarding removable therapy is the loss
of underlying bone height due to direct pressure from the
partial. Hedegard in 1962, Carlsson et al. in 1969 reported
of reduction of height of the mandible in edentulous segments
under removable partial dentures. Preserving the canine
and fabricating an over denture can retard progressive residual
ridge reduction. This procedure has three obvious advantages
for the patient: First, there is increased retention and
stability of the denture base. Second, there is evidence
that the proprioceptive capacity of a patient with a full
denture utilizing some teeth as abutments is dramatically
improved over that seen with a conventional full denture
design. Third, the presence of teeth under a full denture
provides a reduced amount of stress on the edentulous ridges,
resulting in less bone resorption over time.
Caranza and Newman outlined essentials factors concerning
treatment planing for overdenture:
1. The presence of an adequate zone of attached (keratinized)
gingiva around these abutment teeth is of critical importance.
2. Any remaining residual periodontal defects must be treated
in the same way as they would be around any periodontally
involved tooth prior to the final restoration.
Another advantage in the use of overdenture regarding periodontally
involved teeth is that it is possible to improve the crown-to-root
ratio dramatically. This results in a great diminution in
the forces that are applied to the remaining root.
Davis et al. reported the result of a two year longitudinal
study of the periodontal health status of overdenture patients.
Roots were prepared endodontically and capped with amalgam,
low viscosity composite resin sealant, or gold coping. Overdenture
prostheses were constructed with a bilateral balanced occlusal
scheme. Periodontal health status of each of abutment root
were evaluated using color photograph, visual assessment
of tissue tone, color, consistency, and pocket depth measurement
were performed using periodontal probe. Amount of attached
gingiva were also documented. Tooth mobility and bleeding
upon probing were recorded. The results indicated that the
overall pocket depth did not change significantly. The mandibular
teeth, however, showed greater risk of increased pocket
depth than are maxillary teeth when covered with an overdenture.
There was no significant decrease in the width of attached
gingiva in the maxillary teeth but there was such a decrease
in mandibular teeth, which coincided with the increase in
pocket depth of the mandibular teeth. Bleeding upon probing
also increased with 20% of caries incidence found. Nevertheless,
the study concluded that with regular recall of patients,
overdentures appear to be a successful method of treatment.
Renner et al. reported a four-year longitudinal study of
the periodontal health status of overdenture patients. There
were seven patients involved in this study with a total
of 12 roots that were treated with overdentures in both
the maxillary and mandibular arches. The patients were recalled
every six months for a period of 4 years. The findings were
that the gingival tissues around the abutment teeth were
inflamed and bleed on probing. There was no changes in PD
and width of attached gingiva in the same arch, but when
comparing maxillary with mandibular there was a difference.
Half the roots were immobile at the 4 year mark. Lastly
there was a little problem with root caries in 5 of the
teeth. In short, good recall program for oral hygiene instructions
and adjustment is needed.
Budtz-Jorgensen investigated the effect of denture-wearing
habits in 31 overdenture wearers (17 day-and-night wearers,
14 day wearers) during a period of 5 years with controlled
oral hygiene. Prior to prosthetic treatment, intensive instruction
and motivation in oral hygiene were carried out and the
patients were recalled 2-4 x yearly during the study period.
Before treatment, mean plaque index (PlI) and gingival index
(GI) were 1.5 and 1.6, respectively, in both groups of patients.
During the study period, mean PlI and GI were 0.3-0.6 and
0.6-0.8, respectively, in the group of day wearers and 0.5-1.0
and 1.0-1.2, respectively, in the group of day-and-night
wearers. With regard to the GI, this difference was statistically
significant. Furthermore, during the study period, 20% of
the abutment tooth surfaces showed attachment loss (1-4
mm) in the group of day-and-night wearers against 8% of
the tooth surfaces in the group of day wearers. This difference
was statistically significant. During the 5 years, 40 carious
lesions developed in the group of day-and-night wearers
against 3 in the group of day wearers. The results of this
study have shown that day-and-night wearing of dentures
is a major periodontitis and caries risk factor in complete
overdenture wearers with controlled oral hygiene.
Today the best option for treating edentulism distal to
the remaining teeth is dental implants. Many patients who
formerly were treated with removable prosthodontic appliances
(e.g., those with bilateral edentulous areas) can now be
treated with fixed appliances using dental implants as distal
Quirynen et al reported on the use of osseointegrated titanium
fixtures (Branemark) in partially edentulous patients. The
tissue reactions around 509 implants in 97 upper and 71
lower jaws of 146 consecutive patients, rehabilitated by
means of partial bridges--supported by implants only (60%)
or by the combination of teeth and implants (40%)--were
observed longitudinally. The mean number of implants per
bridge was 2.40 (range 1-5) for the upper jaw and 2.06 (range
1-5) for the lower jaw respectively. Before loading, a total
of 23 fixtures were lost, 15 in the upper and 8 in the lower
jaw. This loss could partially be correlated to per- and
post-operative complications and to fixture characteristics
(length, self-tapping or not). After a loading time of 30
months (range 2 to 77 months), 6 implants, 2 in the upper
and 4 in the lower jaw, showed symptoms of non-integration.
The cumulative failure rate for the individual fixtures
after a 6-year period reached 5.7 and 6.5% for the upper
and lower jaw, respectively. The mean annual marginal bone
loss, scored on standardized radiographs, was 0.9 mm during
the 1st year and 0.1 mm the following years. This loss in
marginal bone height was equal in the upper and lower jaws
and not related to the type of occlusal material of the
bridges. The present data showed that the cumulative failure
rate for Branemark implants supporting partial bridges can
be limited to 6% after a 6-year period, and that the radiographic
bone loss is comparable with that found around fixtures
supporting full bridges.
In summary, removable partial denture is an invaluable restorative
option to the patient providing the careful diagnosis and
treatment planing concerning establishing periodontal health,
achieving and maintaining excellent oral hygiene, optimal
design and construction of the prosthesis regarding various
components and occlusal scheme. The success of the therapy
lies in the hands of the clinician who must be totally competent
to render a comprehensive diagnosis of the partially edentulous
mouth and must plan every detail of treatment. With careful
preparation of the patient and accurate design and construction
of the prosthesis, the dentist can preserve the longevity
of the remaining dentition and restoring the functional
and comfort of the patient.
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