Resin bonded fpd /certified fixed orthodontic courses by Indian dental academy

RESIN BONDED FIXED
PARTIAL DENTURE
INDIAN DENTAL ACADEMY
Leader in continuing dental education
www.indiandentalacademy.com

INTRODUCTION


Definition


Resin bonded prosthesis
A prosthesis that is
luted to tooth structure, primarily enamel,
which has been etched to provide
mechanical retention for the resin cement.
-GPT-7

DEVELOPMENT OF
RESIN RETAINED FIXED PARTIAL
DENTURE
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BONDED PONTICS
CAST PERFORATED RESIN RETAINED FPD
(MECHANICAL RETENTION)
ETCHED CAST RESIN RETAINED FPD
(MICROMECHANICAL RETENTION )
MACROSCOPIC MECHANICAL RETENTION
RESIN RETAINED FPD’S
(VIRGINA BRIDGE)
CHEMICAL BONDING RESIN RETAINED FPD’S
(ADHESION BRIDGES)

BONDED PONTICS
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Natural teeth and acrylic teeth used as pontics
Composite resin connectors were brittle and
required supporting wire or a stainless steel
mesh framework
Limited lifetime
Limited to short anterior Spans


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Cast perforated resin retained
FPD

In 1973, Rochette introduced the
concept of bonding metal to teeth
using flared perforations of the metal
casting to provide mechanical
retention. He used the technique
principally for periodontal splinting
but also included pontics in his design.
Howe and Denehy recognized the
metal framework's improved retention
(as compared to bonded pontics) and
began using FPDs with cast‑perforated
metal retainers bonded to abutment
teeth and metal‑ceramic pontics to
replace missing anterior teeth


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Their design recommendation, extending the framework to
cover a maximum area of the lingual surface, suggested little
or no tooth preparation. Patient selection limited these FPDs
to mandibular teeth or situations with an open occlusal
relationship. The restorations were bonded with a heavily
filled composite resin as a luting medium.
This concept was expanded to replacement of posterior teeth.
Perforated retainers were used to increase resistance and
retention." The castings were extended interproximally into
the edentulous areas and onto occlusal surfaces. The design
included a defined occlusogingival path of insertion by tooth
modification, which involved lowering the proximal and
lingual height of contour of the enamel on the abutment
teeth.

Limitations
Weakening of the metal retainer by the perforations
Exposure to wear of the resin at the perforations
Limited adhesion of the metal provided by the
perforations


Etched cast resin retained FPD
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Based on the work of
Tanaka et al on pitting
corrosion for retaining
acrylic resin facings and the
metal etching studies of
Dunn and Reisbick,
Thompson and Livaditis at
the University of Maryland
developed a technique for
the electrolytic etching of
Ni‑Cr and Cr‑Co alloys.
Etched cast retainers have
definite advantages over the
castperforated restorations:

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Retention is improved because the resin‑toetched
metal bond can be substantially stronger than the
resin‑to‑etched enamel.
The retainers can be thinner and still resist
flexing.
The oral surface of the cast retainers is highly
polished and resists plaque accumulation.


Macroscopic mechanical retention resin
retained FPD’S
Several methods have been developed to provide visible
macroscopic mechanical undercuts on the inner
surface of FPD.
The first was developed at the Virginia Commonwealth
University School of Dentistry and is known as the
"Virginia Bridge”.
It involves a "lost salt crystal” technique . On the
working cast, the abutments are coated with a model
spray, and a lubricant is then applied.

Within the outlines of the retainers, specially sized salt
crystals(150 to 250 µm) are sprinkled over the surface in
a uniform monolayer, leaving a 0.5 mm border without
crystals at the periphery of the pattern. This is followed
by application of a resin pattern. After pattern
investment, the salt crystals are dissolved from the
surface of the pattern.
Adequate bond strengths are possible with this method, but
the thickness of the casting mustbe increased to allow
for the undercut thickness.

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An alternative technique for macroscopic
retention is the use of a cast mesh pattern on the
internal surface of the retainers. The mesh,
usually made of nylon, should be adapted to the
lingual and proximal surfaces of the abutments.
The mesh is then covered by wax or resin; this
must be done carefully to prevent occluding the
mesh with the pattern material. Investing and
casting then follow.

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This method is technique sensitive but can
provide adequate retention with a resulting thick
lingual casting.
The cast mesh and the lost salt crystal method
have been supplanted by direct adhesion with
resin, which is possible for most casting alloys if
the correct surface treatment is provided.


Chemical bonding resin retained FPD’S
(Adhesion bridges)
While etched castings were the method of choice for
retention of resin‑retained FPDs during the 1980s and
early 1990s, extensive research was underway to
develop adhesive systems for direct bonding of metal
for this application.
 The first of these resin systems is Super‑Bond which
has the highest initial bond strengths of any adhesive
resin system.
Advantages
 Lower elastic modulus and higher fracture toughness
when compared to BISGMA‑based resin cements
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A BISGMA‑based composite resin luting cement that is
modified with the adhesion promoter MDP .
Panavia has shown excellent bonds to airabraded Ni‑Cr
and Cr‑Co alloys" as well as tinplated gold and gold
palladium‑based alloys.
Panavia has a tensile bond to etched enamel (10 to 15
MPa) comparable to the traditional BISGMA low‑film
thickness composites. The combination of metal
electrolytic etching, followed by application of an
adhesive such as Panavia, does not improve the tensile
bond to the alloy and is actually slightly lower than the
bond of Panavia to airborne‑particle‑abraded
(sandblasted) base metal alloys."

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Recent version of Panavia, Panavia F, is a dual cure system
(chemical and visible light) that releases fluoride. It also
incorporates a self‑etching primer system (ED Primer) for
bonding to enamel and dentin.
Particle abrasion. of the alloy surface with 50 µm alumina before
bonding or tin‑ plating not only creates a roughened, higher
surface area substrate for bonding, but it also creates a molecular
coating of alumina .
The alumina on the surface aids in oxide bonding of the
phosphate‑based adhesive systems (e.g., Panavia to alloy
surfaces). Studies of this bonding mechanism are also reinforced.
by laboratory data on bonding to alumina and zirconia surfaces .
This simplifies the laboratory and clinical procedures for
placement of resin‑retained FPDs

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Laboratory systems for adhesive bonding,resin to
metal have been developed.
Methods
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The flame application of a silica‑carbon layer to the
metal surface. This treated metal is then silane‑coated,
which provides a surface to which composite resin
will bond. The system marketed to the dental
laboratory industry as the Silicoater.
It has since evolved to an oven method to bake the
silica‑carbon layer to the alloy surface and is now
called the Silicoater MD system.

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Another laboratory method for resin bonding is the
Rocatec System. In this method, the metal surface
is initially particle‑abraded with 120 µm alumina.
This is followed by abrasion with a special silicate
particle‑containing alumina. This second particle
abrasion step deposits a molecular coating of silica
and alumina on the alloy surface. Silane is then
applied to the surface, making it adhesive to
composite resin.


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Careful laboratory technique and are generally confined
to bonding composite resin veneers to alloy castings
because of the concern that the silane‑treated surface
may become contaminated before or during the clinical
bonding procedures.
Changing the method of attachment of the resin to the
metal framework does not change the design of the
framework itself, because the limiting factor, in the
system is still the bond of resin to enamel.
There is a need for mechanical retention of the
framework to limit the stress on the bond interfaces
(resin‑to‑metal and resin‑to‑enamel) and in the
composite resin, which can become fatigued with time

Advantages
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Minimal removal of tooth structure
Minimal potential for pulpal trauma
Anaesthesia not usually required
Supragingival preparation
Easy impression making
Provisional not usually required
Reduced chair time
Reduced patient expense
Rebond possible.

Disadvantages
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Reduced restoration longevity
Enamel modifications are required.
Space correction is difficult
Good alignment of abutment teeth is required.
Esthetics is compromised on posterior teeth.


Indications
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Replacement of missing anterior teeth in
children and adolscents.
Short span.
Unrestored abutments.
Single posteior tooth.
Significant crown length.
Excellent moisture control.

Contraindications

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Parafunctional habits.
long edentulous spans.
Restored or damaged abutments.
Compromised enamel.
Deep vertical overlap.
Nickel allergy.


Fabrication
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In the fabrication of resin‑retained FPDs,
following three phases is necessary for
predictable success:
1. Preparation of the abutment teeth
2. Design of the restoration
3. Bonding


Preparation of the abutment teeth
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Common principles dictate tooth preparation
design.
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A distinct path of insertion must exist, proximal
undercuts must be removed to provide "planes of
metal" on the lingual and proximal surfaces,
occlusal rest seats and proximal groove slots must
provide resistance form, and a definite and
distinct margin gingival margin should be
established wherever possible.

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The tooth preparation includes
axial reduction and
guide planes on the proximal surfaces with a slight
extension onto the facial surface to achieve a
faciolingual lock.
should encompass at least 180 degrees of the tooth
to enhance the resistance
extended as far as possible to provide maximum
bonding area
should be a finish line which is placed about 1.0 mm
supragingivally.

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Occlusal clearance is needed on very few teeth: 0.5 mm is
needed on maxillary incisors
Vertical stops are placed on all the preparations consisting of
two or three flat countersinks on the lingual surface of an
incisor, a cingulum rest on a canine or an occlusal rest seat on
a premolar or molar .
Wilkes found rests to be the dominant feature in a
preparation, contributing to both resistance and rigidity.98
The occlusal rest directs the applied force frorn the pontic to
the abutments.
Barrack strongly recommends the use of two rests.

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The resistance features used in a tooth preparation for an
acid etched resin‑bonded retainer will normally be grooves
31% to 77% in study by saad etal and 81% in study by
burgess et al found grooves were found to increase
resistance to displacement on anterior preparations
If there is an existing amalgam, all of the amalgam, or at
least all of its surface, is removed so that the box form can
be utilized
BARRACK et al in his study proposed that the entire
occlusal outline of the existing amalgam restoration is
included within the outline of the retainer's occlusal rest.
HEMBREE et al in his study stated if the retainer margins
cross over an amalgam‑enamel margin, there is a high
probability of leakage occurring around that margin.


Preparation of anterior teeth

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Centric occlusal contacts are marked with articulating paper.
occlusal clearance and lingual reduction of 0.5 mm is done with
small wheel diamond.end this reduction 1.5 2.0 mm from the
incisal edge or just incisal to the incisal most occlusal contact
whichever is closer to the incisal edge

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Counter sinks are placed
Proximal reduction done in facial segment and
lingual segment.

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Lingual axial reduction is done.
Proximal groove and cingulum groove is placed

Preparation for a mandibular incisor and for
maxillary canine


Preparation of posterior tooth

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The basic framework for the posterior resin
retained FPD consists of three major
components:
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occlusal rest (for resistance to gingival displace
ment),
retentive surface (for resistance to occlusal
displacement), and
proximal wrap and proximal slots (for
resistance to torquing forces

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A spoon‑shaped occlusal rest seat is placed in the proximal
marginal ridge area of the abutments adjacent to the
edentulous space. An additional rest seat may be placed on
the opposite side of the tooth .
Proximal and lingual axial surfaces are reduced to lower
their height of contour to approximately 1 mm. from the crest
of the free gingiva.
Proximal surfaces are prepared so that parallelism results
Occlusally, the framework should be extended high on the
cuspal slope, well beyond the actual area of enamel
recontouring
A single path of insertion should exist. The alloy framework
should be designed to engage at least 180 degrees of tooth
structure when viewed from the occlusal .

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This proximal wrap enables the restoration to resist
lateral loading by engaging the underlying tooth
structure and is assisted in this regard by grooves
in the proximal just lingual to the buccal line angle.
Distal to the edentulous space, the retainer
resistance is augmented by a groove at the lingual
proximal line angle.
Moving a properly designed resin‑bonded FPD in
any direction except parallel to its path of insertion
should,,not be possible, nor should it be possible to
displace any tooth to the buccal from the framework

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Preparation differs between maxillary and
mandibular molar teeth only on the lingual
surfaces. The lingual wall of the mandibular
tooth may be prepared in a single plane. The
lingual surface of the maxillary molars
requires a two‑plane reduction due to
occlusal function and the taper of these
functional cusps in the occlusal two thirds.
Lingually inclined mandibular molars (this
may require a twoplane modification)

Preparation for
maxillary premolar

Preparation for mandibular 1 premolar.
Placement of rest seat would leave very
little area in the lingual cusp of premolar
lingual cusp coverage when it does not
interfere in occlusion is an excellent
means of incerasing surface area and
reinforcing the retainer

Preparation for
mandibular 2 premolar


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Preparation for
maxillary molar

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Preparation for
mandibular molar


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Posterior resin bonded fixed partial denture
framework configurations.
Standard
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2 grooves one near the facioproximal angle
adjacent to the edentulous space and one at the
opposite linguoproximal corner, with 180° of axial
wall convergence.


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Two rests : this variation suggested by barrack, has
axial coverage on both proximal walls and teo rest
seats located near the cetral groove at the
mesioocclusal and distoocclusal. They resist
displacement by occlusal forces


Loops : these features are formed by
occlusal inlays being joined to a groove on
a lingual or proximal surface. They brace
the arms


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Lingual cusp coverage: lingual
cusps of mandibular molars and
premolars can be covered to
bolster the retainer againist
deformation.

Tilted molars: mesial and
particularly mesiolingual
tipped molars are out of
occlusion can be covered to
improve occlusion and
remove sublingual food
traps.


Other design concepts
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Occasionally, a combination restoration can be used. This type of
FPD includes a resin‑bonded retainer on one of the abutment
teeth and a conventional cast restoration on the other
Periodontal splinting is the most demanding of the restoration
designs; splints and splint‑FPD combinations require care in
designing adequate mechanical retention
The posterior FPD splint uses multiple rests and distinct
mechanical retention of the abutment in the retainer, which can
be important when the abutment is the most distal tooth in the
arch
The anterior splint must engage as much enamel as possible to
aid in retention and is more demanding in tooth alignment and
preparation design.

FRAME WORK FABRICATION
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MASTER CAST DUPLICATION
RESIN COPING FABRICATION
WAX PATTERN
INVESTING AND CASTING


MASTER CAST DUPLICATION


RESIN COPING FABRICATION


WAX PATTERN


INVESTING AND CASTING


Bonding
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Isolation of abutment teeth by
rubber dam

Tooth facing surfaces of retainers are air abraded using 30-50µm
aluminium oxide. Wash the casting in running water for 1 min and
place in dish washing detergent for 2 min in ultrasonic unit and
then rinse. If noble alloys are used they must be tin plated.

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Abutments are cleaned
with pumice and rubber
cup.

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Etchant is applied to the
teeth for 1 min and then
rinsed of with water and
the abutment teeth are
dried.

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Primer is applied
onto the teeth leave
it for 60 sec .

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Resin pastes are
dispensed and mixed
over a wide area for
25 sec .

Thin layer of mixed resin is
applied to the retainers

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FPD is held in
place for 60 sec.
use a small brush to
clean excess resin

OxyguardII is applied to
protect the resin from
exposure to oxygen


Post operative care
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Should be scrutinized at the regular recall examinations
Early diagnosis and treatment of a partially debonded
prosthesis can prevent significant caries.
Debonding is most commonly associated with biting or
chewing hard food. patients should be warned about this
danger.
Attention to periodontal health is critical, because this retainer
design has the potential to accumulate excess plaque as a result
of lingual over contouring and the gingival extent of the
margins
Calculus removal with hand instruments is recommended over
ultrasonic scalers to reduce the chance of debonding.

Causes of failure
1. Inappropriate patient selection
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Alignment of teeth results in a poor path of
insertion.
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Insufficient vertical length of abutment
teeth.
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Inadequate enamel for bonding.
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History of metal sensitivity.
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Labiolingual dimensions of abutments.

2.Incomplete tooth preparation.
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Insufficient proximal and lingual
surface reduction.
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Incomplete or less than 180°extension of
wraprounds.
Lack of accomodation to mandibular
excursive movement (protrusive)
3.Bonding
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Contamination
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Prolonged mixing.
 Inappropriate luting agent.

REVIEW OF TECHNIQUE
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Patient selection is generally limited to sound abutments with
minimal or no restorations. Occlusion must be stable.
Tooth preparations consist of creating a large lingual bonding
area with proximal wrap; a definite, single path of insertion;
occlusal , incisal or cingulam rest seats; and proximal grooves/
slots.
An accurate elastomeric impression material should be used.
Careful laboratory technique is necessary to ensure a well
fitting and esthetic casting.
Specially formulated resin luting agents that are capable of
adhering to metal should be used to bond the prosthesis.


SUMMARY
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Basic principles of tooth preparation is
conservation of tooth structure.
This is the primary advantage of the resin
retained fixed partial dentures.
A long lasting prosthesis can be provided if
restoration is carefully planned and fabricated.
Careful patient selection is an important factor
in predetermining clinical success

Resin bonded fpd /certified fixed orthodontic courses by Indian dental academy

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