• It is most versatile of the manufactured pontic
• It is used in patients with limited interarch space.
• Here, there are two pins projecting from the
lingual aspect and riveted into gold to aid in
• Good thickness of gold is provided on occlusal or
incisal surface and glazed porcelain provides the
• It is also called interchangeable pontic.
(iv) Modified all ceramic pontic
• It is also called tube tooth.
• All ceramic crowns are with dowel hole.
• This all ceramic pontic is cemented with gold
casting which contacts the gingival surface.
• It is used where occlusion is favourable.
• It has tendency to fracture and also it cannot be
(v) Modified pin facing (Fig. 22-14)
• Here, additional ceramic is added to the pin
facing to form the saddle area.
• It can be used in the patients with decreased
• Advantage: It is aesthetic, can be easily cleaned,
tissue tolerant and comfortable to the patient.
• Disadvantage: It is time consuming, costly and
FIGURE 22-6 Saddle or ridge lap pontic with large concave
FIGURE 22-7 Modified ridge lap with ‘T’-shaped contact with
FIGURE 22-8 Conical or egg-shaped pontic.
FIGURE 22-9 Ovate pontic lies passively in soft tissue
FIGURE 22-10 Hygienic or sanitary pontic.
FIGURE 22-11 Fish belly or conventional sanitary pontic.
FIGURE 22-12 Perel pontic or modified sanitary pontic.
FIGURE 22-14 Flatback interchangeable pontic.
Connectors are an essential part of FPD that join the individual
retainers and pontics together. It is defined as ‘the portion of the fixed
dental prosthesis that unites the retainers and pontics’. (GPT 8th Ed)
Requirements for appropriate connector design
• It should be sufficiently large to prevent distortion or fracture
• It should provide adequate space for effective plaque control.
• Its shape, size and position of connector determine the success of the
• Tissue surface of the connectors should be highly polished.
• Tissue surface of the connector should curve labiolingually to aid in
• In the aesthetic zone, the connectors are usually placed lingually.
• These are the most widely and commonly used
connectors in fixed–fixed bridges.
• All the components are rigidly joined.
• Forces are distributed over two or more abutment
• These are made by flowing wax between the wax
patterns of the retainers and the pontic such that
the bridge is casted in a single unit.
• These are stronger than soldered or welded
• These are convenient, as they do not require
additional procedure of soldering.
• They have more chances of distortion, especially in
• Multiple unit bridges are casted preferably in
several sections and then soldered to get best
• These involve the use of an intermediate metal alloy
whose melting temperature is lower than that of the
• The parts being joined are not melted during
soldering but must be thoroughly wetted by the
• Soldering is the process in which the filler metal has
a melting point below 450°C (842°F) and brazing is
the process in which the filler metal has a melting
• The recommended width between the two
sectioned surfaces to be soldered is 0.25 mm (Fig.
• Large gap decreases solder accuracy, whereas
smaller gap hinders proper solder flow.
• They are indicated in long-span bridges where
• They are also indicated in cases where pontic and
retainers are made separately (e.g. complete metal
crown retainer joined with metal–ceramic pontic).
• It is another method of rigidly joining the metal
• Here, the connection is created by melting adjacent
• A filler metal whose melting temperature is about
the same as that of the parent metal can be used.
• It is used when the diastema is to be maintained in
• It consists of a loop on the palatal aspect that
connects adjacent retainers and/or pontic.
• It can be casted with sprue wax or made with
platinum–gold–palladium alloy (Pt–Au–Pd) wire.
• Adequate space should be provided for effective
• It is indicated in cases where stress breakers are
required usually in long-span bridges. It prevents
the pier (middle) abutment from acting as a
fulcrum either buccolingually or occlusocervically.
• It is used in cases where abutment teeth are
nonparallel and single path of insertion is difficult
(i) Dovetail or Tenon–Mortise or Key–Keyway
• This design consists of a keyway or mortise (female
component) prepared on the retainer and key or
tenon (male component) attached to the pontic (Fig.
• This is the most commonly used nonrigid
• The alignment of this design is critical, as it must
parallel the path of withdrawal of the other
• Parallelism is usually achieved by means of a
• The mortise (female component) may be prepared
free hand in wax pattern or with a precision milling
• Alternatively, a special mandrel is inserted in the
wax pattern and the abutment retainer is cast.
• The female component is refined as necessary; the
male key is fabricated with autopolymerizing resin
• Another approach is to use a prefabricated plastic
component for mortise and tenon of a nonrigid
• Normal movement of a tooth is not interfered with
the use of this type of connectors and, therefore, the
deleterious effects to the supporting tissues are
• It is advantageous from an aesthetic point of view,
as it allows simple type of retainers that require less
cutting of tooth structure which results in a more
• It permits the clinician to finish and cement one
retainer before the rest of the bridge is cemented.
• These do not transmit torsional type of forces from
the bridge to the anterior retainer.
• This type of connector was advocated by R.P.
O’Conner, W.F. Caughman and C. Bemis (1986).
• This is used only in cases with a pier abutment,
which requires excessive preparation due to tilting.
• The connector is incorporated entirely within the
• The pontic is split into mesial and distal segments.
• Each of these segments is attached to their
• First, the mesial segment consisting of mesial
retainer, pontic and pier retainer is fabricated.
• The distal arm of the connector is attached to the
pier retainer and is shaped like tissue contacting
area of the pontic (Fig. 22-17).
• The distal segment is then fabricated with a keyway
• Surveyor is used to align the two segments.
• Cement is not used between the two segments of
• It consists of a two-piece pontic system that allows
the two segments of the bridge to be rigidly fixed.
• It was advocated by F.C. Eichmiller and E.E. Parry
(1994) in cases of tilted abutment.
• Here, the path of insertion of each tooth is made
• A vertical wing is attached to the mesial surface of
• The wing should be fabricated such that it aligns
with the long axis of the mesial abutment.
• The mesial wing along with the distal retainer is
termed as retainer wing component (Fig. 22-18).
• The pontic is attached to the mesial retainer and
designed to fit to the wing in the retainer wing
• The pontic along with the mesial retainer is termed
as the retainer pontic component.
• The retainer pontic component is seated finally.
• After fabricating the retainer wing components,
these are aligned on the working cast and a 0.7 mm
pilot hole is drilled across the wing and pontic
• A rigid pin of 0.7 mm diameter is fabricated using
the same alloy (to avoid galvanic corrosion).
• A pin of 0.7 mm dimension is casted with the same
• The distal retainer and wing assembly are cemented
• Then retainer pontic component is cemented.
• The pin is seated within the pinhole created on the
pontic and wing with the help of a mallet and
FIGURE 22-15 Soldering gap of 0.25 mm is recommended to
FIGURE 22-16 Key–Keyway nonrigid connector.
FIGURE 22-17 Split pontic nonrigid connector.
FIGURE 22-18 Cross-pin and wing.
• FPD replaces one or more teeth and is permanently cemented on the
• Replacement tooth is called pontic. If pontic is supported only at
one end, it is called cantilever pontic.
• Keyway of the connectors should be placed on the distal side of the
pier abutment so that on mesial movement the key has a seating
• If keyway is placed on the mesial side of the pier abutment, it will
have unseating effect on mesial movement.
• If the tilted molar tooth is mesially and lingually inclined, then
nonrigid connectors should be used.
• Sanitary or hygienic pontic is indicated in posterior region of the
lower jaw, as it provides good access for hygiene maintenance.
• Undersurface of the sanitary pontic is made round for easier
flossing. This design is called fish belly.
• Modified design of sanitary pontic is concave archway
mesiodistally. This design is called arc-fixed partial denture or
• Modified ridge lap design is indicated in the high aesthetic zone in
maxillary anteriors and bicuspid region.
• Ovate pontic provides superior aesthetic and is indicated in the
maxillary anterior region and bicuspids.
• Conical or egg-shaped or bullet-shaped or heart-shaped pontic is
indicated in the nonaesthetic zone, i.e. in cases of lower posterior
• Scalloped or trestle design of the connector is desired as the height
of the metal strut is increased incisogingivally in order to enhance
• Recommended gap width between two surfaces to be soldered is
0.15 mm and optimum width should be 0.20 mm.
• Borates are used as soldering flux for noble metal alloys and
fluorides are used as soldering flux for base metal alloys.
• The occlusal surface of the pontic should not be more than 85% of
the occlusal surface of the tooth to be replaced.
• Brazing takes place when the melting temperature of the filler metal
• Soldered parts should not be quenched immediately, as this will
produce thermal stresses, which lead to distortion.
• The intracoronal retainers are usually contraindicated in young
adults because of high pulp horns.
planning in fixed partial denture
Common Medical Conditions Which Influence
Abutment and Factors Influencing Abutment
Different Types of Abutments used in Fixed
Residual Ridge Defects and Their
Periodontal Factors Which Influence Treatment
Planning in Fixed Prosthodontics, 342
A successful fixed partial denture (FPD) depends on the accurate
diagnosis and treatment planning. For this, the patient’s intraoral and
extraoral conditions along with the psychological needs are
thoroughly evaluated. The diagnostic information is collected after
taking a proper medical and dental history and clinically examining
the patient. This information helps in formulating a treatment plan
which best suits the condition of the patient.
Diagnosis is defined as ‘determination of nature of disease’. (GPT 8th
The essential elements which are necessary for proper diagnosis in
• Extraoral examination including TMJ and occlusal evaluation
Common medical conditions which influence the
There are a number of medical conditions which influence the
treatment in fixed prosthodontics. The most common medical
conditions encountered in dentistry are given below.
Diabetes: A diabetic patient should be under medication and strict
diet supervision of the physician. These patients require proper
education on oral hygiene maintenance, eating habits and tissue rest.
A patient with uncontrolled diabetes is under the risk of:
• Bacterial, viral and fungal infections including candidiasis.
• Xerostomia may cause dry atrophic oral mucosa, inflamed
• Insulin shock in patient treated with insulin.
Diabetic patients should be given short appointment which should
not interfere with their meal time.
Cardiovascular diseases: The patients with a history of rheumatic fever
and rheumatic heart disease are at an increased risk of infective
endocarditis. Prophylactic antibiotic is must for such patients. A
patient with pacemakers should be treated with caution. The
patient’s physician should be consulted before performing any
invasive procedure. Short appointment preferably in the morning
should be given. The patients can be premedicated with diazepam
5–10 mg to reduce anxiety. The procedure should not stress the
patient, as stress and anxiety can precipitate angina. Adrenaline
dose in the local anaesthesia should be reduced.
Neurological disorders: The patients with disorders such as cerebral
palsy, Bell palsy or Parkinson disease should be treated with utmost
care. It is difficult for the patient to give adequate interocclusal
record. Such patients have poor dexterity and have difficulty in
maintaining good oral hygiene.
Disease of the skin: Dermatological conditions such as pemphigus
often have oral manifestations that are extremely painful. Invasive
procedures in such patients should be avoided.
Disease of joints: Conditions such as osteoarthritis mainly affects the
weight-bearing joints (e.g. hips, knee and spine). In some cases,
terminal joints such as fingers and TMJ may also be affected. This
condition is more common in females than in males. Osteoarthritis
of TMJ makes the jaw relation recording difficult. Sometimes due to
limited mouth opening, special impression trays or sectional trays
may be required to make impressions.
Radiation therapy patient: The patients who have undergone
radiation therapy tend to develop problems such as mucositis,
muscle contractures, xerostomia and secondary infection such as
candidiasis, loss of taste and in extreme cases osteoradionecrosis.
Diagnostic aids used in fixed prosthodontics
Complete clinical examination along with the use of certain diagnostic
aids is important for accurate diagnosis and treatment planning in
fixed prosthodontics. Some of the diagnostic aids commonly used for
diagnosis and treatment planning in fixed prosthodontics are:
• Vitality testing with thermal or electrical stimulation
Diagnostic casts are one of the most vital aids used for accurate
diagnosis and treatment planning. Diagnostic casts are fabricated after
making accurate impressions of both the arches. The impression
material commonly used is irreversible hydrocolloid (alginate). The
casts are mounted on the semi-adjustable articulator after facebow
transfer and accurate interocclusal record.
Accurately mounted diagnostic casts are helpful in assessing the
following characteristics (also refer to Chapter 15):
• The teeth, soft tissue contours, bony undercuts and frenal
• The edentulous ridge and span length
• Location, height, rotation and tilt of the abutment
• Analysis of the occlusion, to assess any premature contact
• Unobstructed view of occlusion from the lingual side
• Crown length morphology and vestibular depth
• Gives preview of the aesthetic form
Importance of radiographic interpretation for
successful treatment planning in fixed
Radiographic examination is a crucial diagnostic aid which should be
used as an adjunct to the complete clinical examination. It provides
information which usually is not determined clinically. The findings
from radiographic examination should be carefully correlated with
other findings in order to achieve an accurate and definitive diagnosis.
The radiographs are helpful in detecting the following characteristics
• Carious lesions, condition of existing restoration
• Quantity and quality of the supporting bone
• Root morphology, crown-to-root ratio
• Inclination of the abutment tooth
• Pulpal morphology and quality of any previous endodontic
• Retained root fragments, impacted tooth/teeth
• Continuity and integrity of the lamina dura
• Status of periodontal ligament space, calculus deposits
Abutment and factors influencing abutment
Abutment is defined as ‘a tooth, a portion of the tooth or that portion of an
implant used for the support of a fixed or removable prosthesis’. (GPT 8th
Selection of the appropriate abutment is very crucial for the success
of fixed prosthesis. Abutment tooth should be strong enough to bear
the functional forces directed not only to them but also to the missing
teeth/tooth. There are a number of criteria for selecting an appropriate
• It should have a good bone support.
• It should have a good periodontal status.
• It should be healthy without any inflammation.
• It should have adequate amount of coronal tooth structure.
• It should have a favourable crown-to-root ratio.
• It should be vital tooth, if not then an endodontically treated tooth
Factors Influencing Abutment Selection
• Location, angulation and condition of the abutment
Crown-to-root ratio: This is the ratio between the tooth which is
above the alveolar crest and the portion of the root which is
surrounded by bone. The recommended ratio between the crown
and the root is 2:3 for an ideal abutment. However, minimal ratio of
1:1 may be acceptable for abutment under normal condition. In
cases where the opposing occlusion consists of denture teeth or the
natural teeth which are periodontally weak, crown-to-root ratio
greater than 1:1 may be acceptable but with caution. Longer the
edentulous span, greater the torque on the abutment tooth and
more favourable should be the ratio. Multiple abutments can
sometimes compensate for poor crown-to-root ratio or be useful in
Root configuration: This factor determines the suitability of the
prospective abutment tooth. Multirooted posterior teeth provide
better support than the single-rooted anterior teeth. Posterior teeth
have a broader occlusal table and better bone support than anterior
teeth. Multirooted teeth with divergent roots are advantageous than
teeth with convergent or fused root. Likewise, a single-rooted tooth
Condition of the abutment: Healthy abutment tooth is always more
preferred to periodontally compromised or mobile tooth.
Location of the prospective abutment: This is an important factor as
the configuration and the design of fixed prosthesis can be planned
accordingly. Narrow dental arch will be subjected to greater
leverage forces than the wider arch.
Angulation of the abutment: J.M. Reynolds (1968) has suggested that
the abutment tooth should not incline more than 25–30°, as the
tooth is in best position to bear the vertically directed forces along
the long axis of the tooth. If the tooth is severely inclined, the
harmful torquing forces will be distributed to the tooth. Mesially
tilted or distally tilted tooth requires modification in tooth
preparation. The situation can demand more tooth reduction or
Root surface area: It is also called the pericemental area of the
abutment tooth; this is another important consideration. Larger is
the tooth, more the root surface is available and better it is to bear
the functional forces. Ante’s law is followed as a clinical guideline
to select an appropriate abutment.
FIGURE 23-1 Recommended crown–root ratio.
FIGURE 23-2 Various root configuration of teeth.
I.H. Ante in 1926 stated that ‘the abutment teeth should have a
combined pericemental area equal or greater than the tooth or teeth to
be replaced’. This statement was referred by J.F. Johnston in 1971 as
FIGURE 23-3 Ante’s law – the combined pericemental area
of second premolar and second molar should be greater
Ante’s law helps in evaluating the pericemental area of the abutment
teeth. Larger tooth with greater surface area bears the functional
forces better than smaller tooth with lesser surface area. The root
surface areas of maxillary and mandibular teeth have been reported
by A. Jepsen. The values given by Jepsen may not always be relevant
to the given clinical situation. In the clinical situation, the proposed
abutment tooth may have reduced bone support due to periodontal
reasons. In such cases, the capacity to bear functional forces by this
tooth may be questionable and this should be considered while
making proper diagnosis and treatment planning.
Ante’s law is used as a clinical guideline to plan treatment in fixed
prosthodontics. The recommended crown-to-root ratio is 2:3 and a
ratio of 1:1 is considered minimal to accept the prospective abutment
for FPD. A ratio of 1:1 or more will satisfy Ante’s law. Shorter span
FPD has better prognosis than the longer span dentures. Abutment
tooth should be carefully selected by giving due consideration to the
location, occlusion, angulation, bone support and periodontal status.
In cases of bone loss due to periodontal reasons, mesial or distal
drifting of abutment, endodontically treated tooth, mobility or
unfavourable occlusion, the law can be modified by increasing the
Rigidity of FPDs: The lack of rigidity of the prosthesis is one of the
major causes of failure. The denture should be rigid and should
have good flexural strength to resist the masticatory forces. Flexure
can have a damaging effect on the abutment, especially in cases of
Different types of abutments used in fixed partial
The type, status and location of the abutment tooth determine the type
Types of Abutments Commonly Used in
• Unrestored or ideal abutment
• Endodontically treated abutment
(i) Unrestored or ideal abutment
This type of abutment is a healthy, caries-free,
periodontically sound tooth with adequate clinical
height. It provides best prognosis for fixed
prosthesis. Some desirable features of ideal
• It should have adequate bone support.
• It should have optimum crown-to-root ratio.
• It should be periodontically healthy.
• It should have sound tooth structure with adequate
Pier abutment is defined as ‘a natural tooth located
between the terminal abutments that serve to support a
fixed or removable dental prosthesis’. (GPT 8th Ed)
A pier abutment is a lone standing tooth with
edentulous spaces present both mesially and
distally to it. In long-span FPD where support is
sought from the pier abutment and the adjacent
teeth, there are chances of more stress concentration
around the abutment teeth when rigid connectors
are used. Factors which influence the amount of
stress on the abutment teeth are position of the
abutment in the arch, physiological tooth
movement and retentive capacity of the retainers.
The middle abutment acts as the fulcrum and the
excessive forces transmitted to the terminal
retainers cause the weaker retainer to loosen. This
causes marginal leakage, secondary caries and
ultimately prosthesis failure. In such situations,
nonrigid connectors are recommended which help
in transferring the stresses to the supporting bone
The commonly used nonrigid connectors or the
stress-breaking device consists of key and
keyway. The stress-breaking device is usually
placed on the pier abutment. The keyway is placed
on the distal contour of the pier abutment and the key
is placed on the mesial side of the distal pontic. Mesial
movement of the posterior teeth in function results
in proper seating of the key into keyway.
However, nonrigid connectors should be avoided in
situation where the following characteristics are
• The abutment tooth/teeth are mobile.
• The posterior abutment and the pontic are opposed
with removable denture or are unopposed. In such
situations, the posterior teeth tend to supraerupt
thereby unseating the key from the keyway.
Molar teeth posterior to the edentulous space tend to
drift mesially into it, if the space is not restored.
Tilted molar tooth, if used as an abutment, makes it
difficult to achieve a single path of insertion. The
situation becomes even more complex, if third
molar is present next to the tilted second molar
tooth. Severely tilted tooth should be avoided, if it
is used as an abutment. However, if only single
tilted tooth is present distal to the edentulous space,
it should be considered as an abutment.
Tilted molar tooth used as an abutment can be
corrected by one of the following methods:
(a) Recontouring or restoration of the mesial
surface of the tilted molar: This is followed in
(b) Orthodontic treatment: If there is severe tilting
of the molar tooth, the treatment of choice should
be orthodontic uprighting of the tilted molar
tooth. This is achieved by using a fixed appliance.
If third molar is present next to the tilted second
molar, it is best extracted to allow distal
(c) Modified partial veneer crown: Mesial half
crown or modified partial veneer crown can be
used as retainers on the tilted abutment tooth.
The distal half of the crown is left unprepared,
whereas the mesial half is prepared to achieve
(d) Telescopic crown: It is defined as ‘an artificial
crown constructed to fit over a coping (framework).
The coping can be another crown, a bar or any other
suitable rigid support for the dental prosthesis’. (GPT
The tilted molar abutment is radically reduced to
fabricate a coping. This coping ensures good
marginal adaptation. A telescopic crown is then
fitted over this coping to get a favourable path of
(e) Nonrigid connector: A full veneer preparation is
done for the tilted molar tooth along its long axis.
The mesial abutment is prepared on its distal
surface to form a keyway. An FPD is fabricated to
slide into this keyway. The distal abutment (tilted
molar tooth) has a rigid connector, whereas the
mesial abutment (premolar) has a nonrigid
connector. The nonrigid design should not be
indiscriminately used as its cantilevering effect
produces additional lateral stresses harmful to
the abutment tooth with rigid connector. This
method is more useful, if the molar tooth is tilted
both mesially and lingually. The nonrigid design
is avoided in long-span bridges (Fig. 23-6).
(iv) Cantilevered fixed dental prosthesis
Cantilevered dental prosthesis is defined as ‘a fixed
dental prosthesis in which the pontic is cantilevered, i.e.
is retained and supported only on one end by one or more
As this type of design is supported only at one end, it
has the potential to damage the supporting
abutment tooth. The pontic of the cantilevered FPD
acts as a lever which tends to apply harmful
leverage forces to the abutment tooth. The
abutment tooth or teeth supporting a cantilevered
FPD should have the following characteristics:
• Favourable crown-to-root ratio
• Long roots with sufficient height of clinical crown
Cantilevered FPD can be used to replace maxillary
lateral incisor taking support from the canine and
can be used to replace mandibular first premolar
taking support from the second premolar and the
first molar. The cantilevered pontic should not have
any contact in lateral excursion and should have
light occlusal contact. Posterior cantilevered pontic
should be made of smaller size so as to avoid
excessive forces on the abutments. Cantilevered
FPD should be avoided in periodontically
An endodontically treated tooth is contraindicated as
an abutment to a cantilevered FPD, as it is subjected
to fracture because of considerable loss of
significant supporting dentin. However, double
abutment with splinted retainers can be used in
FIGURE 23-5 Telescopic coping used on tilted molar to
achieve favourable path of insertion.
FIGURE 23-6 Nonrigid connector given on the distal surface
of premolar to compensate for inclined molar.
FIGURE 23-7 Cantilevered pontic tends to apply leverage
forces to the supporting abutment tooth.
Residual ridge defects and their management
During the intraoral examination, it is very important to assess the
condition of the residual ridge. The shape, consistency, type, location
and the amount of resorption determine the course of treatment in
fixed prosthodontics. Proper assessment of the amount of destruction
of the residual ridge helps in determining the design of pontic.
J.S. Siebert (1983) Classified the Residual
Ridge Defects into the Following Three
(i) Class I: Has a normal ridge height with loss of faciolingual ridge
(ii) Class II: Has a normal faciolingual ridge width with loss of ridge
(iii) Class III: Loss of both ridge height and width (Fig. 23-10).
(iv) Class N: No loss or minimal deformity of the ridge; this category
was later added and was not a part of the original Siebert’s
FIGURE 23-8 Siebert’s class I – normal height, reduced
FIGURE 23-9 Siebert’s class II – reduced height, normal
FIGURE 23-10 Siebert’s class III – reduced height, reduced
Residual ridge defects can be surgically corrected by various
techniques. These techniques are helpful in changing the shape of the
ridge to create an aesthetically acceptable and easy cleanable area.
Techniques Used to Correct Ridge Defects
(i) Soft tissue ridge augmentation
(iii) Siebert’s onlay graft or thick free gingival graft
(i) Soft tissue ridge augmentation: H. Abrams (1980) gave the roll
technique to augment the ridge with soft tissues for class I defects. In
this technique, the palatal epithelium is removed and is rolled back
upon itself in order to thicken the facial aspect of the residual ridge.
Pouch technique can also be used to increase the width of the ridge.
(ii) Interpositional graft: This can be used to correct class II and class
III defects. The epithelium is removed from the facial aspect and then
the pouches are formed into which the connective tissue graft is
inserted. It ensures an increase in the ridge height and is helpful in
(iii) Siebert’s onlay graft or thick free gingival graft: It is useful in
treating class III defects, as it increases both the ridge height and the
width. In this technique, the recipient bed is prepared by removing
the epithelium and making striations to induce bleeding. These
induced bleeding points encourage vascularization in the connective
tissues. Onlay graft is then harvested from the palate region of
tuberosity or premolar–molar vault region and is sutured in place. A
temporary crown is placed immediately so as to allow tissue
adaptation during healing. Healing requires around 6–8 weeks.
(iv) Gingival porcelain: Gingival or pink porcelain can be added to
simulate the interdental papilla. It is helpful in mandibular molar and
(v) Ridge augmentation: This can also be done with allograft material
such as hydroxyapatite, tricalcium phosphate or freezed dried bone.
Ridge defects are usually not filled with these materials until implants
Andrews’ bridge is defined as ‘the combination of a
fixed dental prosthesis incorporating a bar with a
removable dental prosthesis that replaces teeth within the
bar area, usually used for edentulous anterior spaces.
The vertical walls of the bar may provide retention for
the removable component’. (GPT 8th Ed)
This bridge system was first advocated by James
Andrews (1983) to restore large ridge defects (class
II and class III). It is composed of fixed retainers
which are connected by a rectangular bar that
follows the ridge curve. A removable denture is
seated onto the rectangular bar by means of a clip.
This kind of fixed removable prosthesis is indicated
for restoring large vertical ridge defect.
Disadvantages of this system are food lodgement
and plaque entrapment (Fig. 23-11).
Periodontal factors which influence treatment
planning in fixed prosthodontics
There are a number of periodontal factors which can influence the
diagnosis and treatment planning in fixed prosthodontics. Some of
(i) Periodontitis: It is an inflammatory disease of the gums and is
characterized by pocket formation and bone destruction. It is one of
the common reasons for which the patient may lose one or more teeth
and require fixed prosthodontic treatment. Periodontal therapy is
indicated for a patient with periodontitis. The goals of this therapy are
to resolve inflammation, provide adequate attached gingiva and
convert periodontal pockets to clinically normal sulcular depths.
(ii) Trauma from occlusion: This refers to tissue injury produced by
the functional forces. Clinical signs that suggest trauma from
occlusion are excessive tooth mobility, angular or vertical bone loss,
pathological tooth migration and infrabony pockets.
(iii) Embrasure spaces: The space located below the contact area
between teeth is called the embrasure space. Embrasures deflect the
food at the time of mastication and protect the gingiva from food
impaction. The proximal surfaces of restoration should be designed in
such a way that it does not encroach into the embrasure space or else
it leads to gingival inflammation. Therefore, the restoration should not
be overcontoured or undercontoured.
(iv) Margin placement: Supragingival margins are always
recommended whenever possible for proper periodontal health.
However, subgingival margins are indicated in cases of extension of
caries, pre-existing restoration, areas of cervical erosion and root
fracture or for aesthetic reasons.
(v) Biologic width: A combined width of the connective tissue and
epithelial attachment averaging 2.04 mm is called biologic width. A
minimum dimension of 3 mm to the alveolar crest is necessary for
proper healing and restorations. The width should not be violated, as
it results in attachment loss and ultimately bone loss (Fig. 23-12).
FIGURE 23-12 Schematic diagram representing biologic
• Xerostomia is common to autoimmune disorders such as Sjogren
syndrome, rheumatoid arthritis, lupus erythematosus and
• Ante’s law is the abutment teeth should have total pericemental
area equal to or greater than the pericemental area of the tooth/teeth
• Ideal crown:root ratio is 1:2, optimum or recommended is 2:3 and
• If edentulous space exists on either side of the abutment tooth, such
tooth is called pier abutment.
• Tilted molar is best uprighted by orthodontic means.
• Root amputation is removal of root without touching the crown.
• Hemisection is a procedure in which tooth is separated through
• Radectomy is a process of resection of root.
• Ratio of 1.618:1.0 is called golden proportion and is a constant.
• Andrews’ bridge is indicated when there is large anterior ridge
defect. It is a rectangular bar which is connected to the fixed
retainers and follows the curve of the arch.
• Mandibular first molar is most frequently replaced by FPD.
Design of fixed partial denture
Different Designs in Fixed Prosthodontics, 344
Biomechanical Factors Affecting FPD
Steps in Tooth Preparation, 348
Rationale of Restoring an Endodontically Treated Tooth and Ideal
Ideal Requirements of a Post, 349
Tapered Smooth-Sided Post, 350
Tapered Post with Self-Threading Screws, 350
Steps Involved in Fabrication of Custom-Made
Resin Cements Used to Lute FPDs, 357
One of the most important reasons for success of fixed dental
prosthesis is proper designing of FPDs. It is essential for a clinician to
understand different designs of FPDs, which can be used in a given
Different designs in fixed prosthodontics are:
• Fixed–fixed partial denture (FPD)
• Resin-bonded tooth-supported FPD
• Fixed–removable partial denture
Factors influencing the design of FPD are:
Biomechanical factors affecting FPD design
The major biomechanical factors affecting the design of FPD are:
• Occlusogingival height of the pontic
• Direction of forces acting on FPD
• Longer the edentulous span, more will be the load
• As the length of span increases, the destructive
torquing and leverage forces increase on the
• Length of the span influences the number of
abutment to be used – Ante’s law can be a useful
• Flexion of the FPD is directly proportional to the
cube of length and inversely proportional to the
cube of occlusogingival height of the pontic.
• Two-tooth pontic will show eight times more
flexion than single-tooth pontic.
• Similarly, three-tooth pontic will show 27 times
more flexion than a single-tooth pontic.
(ii) Occlusogingival height of the pontic
• Flexion or bending of FPD can be minimized by
selecting the pontic design with greater
• If the occlusogingival height of the pontic is halved,
it is likely to flex eight times more than the original
• To minimize flexion, the prosthesis can be
fabricated with material having higher modulus of
elasticity (e.g. nickel–chromium alloy).
• The problems encountered in long-span FPD or
unfavourable crown-to-root ratio can be overcome
by using double abutment (primary and
• The secondary abutment should have as much
surface area and favourable crown-to-root ratio as
• It should also have retainers as retentive as the
primary abutment in order to bear the forces of
(iii) Direction of forces acting on FPD
• The forces applied on FPD are different in
magnitude and direction as compared to the singletooth restoration.
• Usually all FPDs (long or short) show flexion to
• The dislodging forces on the single restoration act in
the buccolingual direction and in cases of FPDs,
these act along the mesiodistal direction.
• In order to counteract these dislodging forces, the
preparation should be modified by providing
multiple grooves to enhance the structural
durability and resistance form.
• The curvature of the arch affects the amount of
• If a pontic lies outside the interabutment axis, it acts as
lever arm which produces harmful torquing forces
that may weaken the abutment or facilitate
• In order to counteract the torquing forces,
secondary abutment is used in the direction
opposite to the lever arm and the distance between
the interabutment axes should be made equal to the
• For example, when all four maxillary incisors are to
be replaced, the maxillary canine on both the sides
acts as primary abutment and the maxillary first
premolar forms the secondary abutment. The
distance between the primary and secondary
interabutment axes is made equal to the distance
between the primary interabutment axis and pontic
lever arm to best counteract the torquing forces
• Number of teeth to be used as abutment influences
• Position of the edentulous span, position of the
abutment teeth which they occupy in the arch and
periodontal health of the teeth influence the design
FIGURE 24-1 If occlusogingival height of pontic is halved, the
flexion of FPD will be eight times greater.
FIGURE 24-2 Distance between primary and secondary
interabutment axes and pontic lever arm.
In recent times, all ceramic FPDs are becoming popular due to
aesthetic reasons. Although their use was discouraged because of
inferior strength in comparison to metal ceramic FPDs, lots of
materials are tried to fabricate all ceramic FPDs with varied success. In
the past, aluminous porcelain was used to fabricate by connecting
alumina cores with pure alumina rods without much success. Then
leucite-reinforced heat-pressed ceramic was tried but failed due to
inferior strength. Recently introduced In-Ceram zirconia, lithium
disilicate, heat-pressed ceramic and CAD/CAM (computer-aided
designing and computer-aided machining) Procera systems are
becoming popular fast, as they possess adequate strength to be used
successfully in fabricating anterior FPDs. All ceramic FPDs made of
any material should have connectors of dimension 4 × 4 mm in
comparison to metal connectors which require 2 × 3 mm of width.
Disadvantage of this excess width of connector is difficulty in plaque
control. The core material containing 33% of zirconia can provide
adequate strength to be used in posterior FPDs.
Laminate veneer is defined as ‘a superficial or attractive display in
‘a thin sheet of material usually used to finish’. (GPT 8th Ed)
Laminate veneer is a conservative method to aesthetically restore
the appearance of discoloured or deformed tooth. It consists of thin
ceramic laminate which is luted onto the labial surface of the affected
tooth. Tooth preparation is mostly confined only to the enamel.
• Porcelain veneers were first used by Charles Pincus between 1930
• Preformed veneers were bonded onto the etched tooth surface and
this procedure is called laminating.
• Using glazed ceramic improved colour stability, abrasion resistance
and was well tolerated by the gingiva.
• Etching the ceramic veneer with hydrofluoric acid improved the
bond strength between the luting agent and the veneer.
• Again incorporation of silane coupling agent improved the shear
bond strength of ceramic veneer and expanded its use.
• Teeth with intrinsic staining (e.g. tetracycline stains)
• Correction of mild form of malformed anterior teeth
• Patient with poor oral hygiene
• It requires minimal preparation.
• The preparation is confined only to enamel.
• It is wear and stain resistant.
• There are chances of debonding.
• Minimal preparation is required and this is confined usually only to
• Finish line is a slight chamfer which is placed at the gingival crest or
• Minimal thickness for ceramic veneer is about 0.3–0.5 mm.
• Cuts of about 0.3–0.5 mm depth are given.
• Round-end-tapered diamond is used to reduce the labial surface.
• Slight chamfer finish line is created at the level of the gingiva.
• It is an extension of the labial reduction proximally.
• Preparation is extended to the gingival crest and into the contact
• The contact area should be left intact.
• It involves two techniques of placing incisal finish line.
• In the first technique, there is no incisal reduction and the
preparation of the labial surface ends at the incisal edge.
• In the second technique, the incisal surface is reduced and the
ceramic overlaps the incisal surface and ends on the lingual aspect.
• Ceramic is said to be stronger in compression than in tension, and
therefore, the second technique is preferred.
• Lingual finish line is created with round-end-tapered diamond.
• The finish line should be at least 1.0 mm away from the centric
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