Sturdevant's Art and science of operative dentistry.2013 Mosby Elsevier . Sixth
Edition chapter 10 pep 254
Contemporary esthetic dentistry .2012 Mosby Elsevier. first Edition chapter 10
Tooth colored restorative ,principle and techniques . 2012 Albers .ninth edition
When esthetic dentistry began its evolution, the posterior teeth
were considered unimportant. As patient expectations have
increased, more focus has been placed on the esthetic
contribution of posterior teeth With the mechanics of
mandibular function, as humans speak, laugh, and exhibit the
behaviors considered human, the incisal edges of the lower
anterior teeth and the occlusal surfaces of the posterior teeth
are critical .
composite resin is three dimensional combination of two or
more chemically different materials with a distinct interface
between them.in combination, the properties are superior to
those of individual components.
Composites are indicated for Class 1, class 2 and class 5 defects on
premolars and molars. Ideally, an isthmus width of less than one third the
intercuspal distance is required.
This requirement is balanced against forces created on remaining tooth
structure and composite material. Forces are analyzed by direction,
frequency, duration and intensity. High force occurs with low angle cases,
in molar areas, with strong muscles, point contacts and parafunctional
forces such as grinding and biting finger nails.
Composite is strongest in compressive strength and weakest in shear,
tensile and modulus of elasticity strengths.
Failure of a restoration occurs if composite fractures, tooth fractures,
composite debonds from tooth structure or micro-leakage and
subsequent caries occurs. A common area of failure is direct point contact
by sharp opposing cusps.
DIRECT POSTERIOR COMPOSITES
Tooth preparation requires adequate access to remove caries, removal of
caries, elimination of weak tooth structure that could fracture, beveling of
enamel to maximize enamel bond strength, and extension into defective
areas such as stained grooves and decalcified areas.
Matrix systems are placed to contain materials within the tooth and form
proper interproximal contours and contacts
Enamel and dentin bonding is completed. Composite shrinks when cured
so large areas must be layered to minimize negative forces.
Generally, any area thicker than two millimeters requires layering. In
addition, cavity preparation produces multiple wall defects.
Composite curing when touching multiple walls creates dramatic stress
and should be avoided.
Composite built in layers replicate tooth structure by placing dentin layers
first and then enamel layers.
Final contouring with hand instruments is ideal to minimize the trauma of
shaping with burs.
Matrix systems are removed and refined shaping and occlusal adjustment
done with a 245 bur and a flame shaped finishing bur. Interproximal buccal
and lingual areas are trimmed of excess with a flame shaped finishing bur.
Final polish is achieved with polishing cups, points, sandpaper disks, and
Composite materials shrink while polymerizing. This is
referred to as polymerization shrinkage. This phenomenon
cannot be avoided, and important clinical procedural
techniques must be incorporated to help offset the
potential problems associated with a material pulling away
from the preparation walls as it polymerizes. Careful control
of the amount and insertion point of the material and
appropriate use of an adhesive on the prepared tooth
structure to improve bonding reduce these problems.
There are several mechanisms of composite wear
including adhesive wear, abrasive wear, fatigue, and chemical wear:_
Adhesive wear is created by extremely small contacts and therefore
extremely high forces, of two opposing surfaces. When small forces
release, material is removed. All surfaces have microscopic roughness
which is where extremely small contacts occur between opposing surfaces.
Abrasive wear is when a rough material gouges out material on an
opposing surface. A harder surface gouges a softer surface. Materials are
not uniform so hard materials in a soft matrix, such as filler in resin, gouge
resin and opposing surfaces.
Fatigue causes wear. Constant repeated force causes substructure
deterioration and eventual loss of surface material.
Chemical wear occurs when environmental materials such s saliva, acids
or like affect a surface.
Significance of Gap Formation
The gap formation that usually occurs when the composite
restoration is extended onto the root surface may not have any
long-term clinical effects. With the two vectors of the defect
being primarily resin or composite, recurrent caries may not be a
problem. How long the exposed hybridized resin layer on the
root stays intact is unknown, however, and if it deteriorates in a
short time, the area is exposed to risk for caries. Use of an RMGI
liner material may reduce the effect of gap formation by
rendering the surrounding tooth structure more resistant to
Dental composite is composed of a resin matrix and filler materials. The
resin filler interface is important for most physical properties.
There are three causes of stress on this interface including:
i. resin shrinkage pulls on fillers, filler modulus of elasticity is
higher than resin, and filler thermo coefficient of expansion
allows resin to expand more with heat.
ii. When fracture occurs, a crack propagates and strikes a
filler particle. Resin pulls away from filler particle surfaces
during failure. This type of failure is more difficult with
larger particles as surface area is greater. A macrofill
composite is stronger than a microfill composite.
iii. Coupling agents are used to improve adherence of resin to
1) Class-I, II, III, IV, V & VI restorations.
2) Foundations or core buildups.
3) Sealant & Preventive resin restorations.
4) Esthetic enhancement procedures.
6) Temporary restorations.
7) Periodontal splinting.
INDICATIONS of composite
1) Inability to isolate the site.
2) Excessive masticatory forces.
3) Restorations extending to the root surfaces.
4) high caries incidence and poor oral hygiene.
The advantages of composite as a Class I and II direct restorative
material relative to other restorative materials are:
2. Conservative tooth structure removal
3. Easier, less complex tooth preparation
5. Decreased microleakage
6. Increased short-term strength of remaining tooth
The disadvantages of Class I and II direct composite restorations
are as follows:
1. Polymerization shrinkage effects
2. Lower fracture toughness than most indirect
3. More technique-sensitive than amalgam restorations
and some indirect restorations
4. Possible greater localized occlusal wear.
5. Unknown biocompatibility of some components
(bisphenol A [BPA])
Marketed for posterior use
increase in viscosity
better proximal contacts
handle like amalgam
Subtle alteration of filler
Similar resin chemistry and filler volume
Proximal Contact Studies
Packables similar to hybrids
diameter and tightness
sectional matrix system
Advanced composite for direct
Bulk Fill Composite
Advanced composite technology allows for directly placed posterior
restorations with bulk-fill resin-bonded composite in a single
increment. Engineered with a smooth and creamy consistency, bulk-fill
composite (eg, Tetric EvoCeram® Bulk Fill, Ivoclar Vivadent , can
achieve high marginal adaptation to the floor and walls of cavity
preparations, eliminating the need for a flowable liner. The patented
shrinkage stress reliever technology increases marginal integrity and
decreases polymerization shrinkage due to a low shrinkage stress of
1.13 MPa and a low shrinkage volume of 1.9%.Good marginal integrity
and low polymerization shrinkage can result in a decreased probability
of tooth deformation, postoperative sensitivity,microleakage, and
1) Local anaesthesia.
2) Preparation of the operating site.
3) Shade selection
4) Isolation of the operating site.
5) Tooth preparation.
6) preliminary steps of enamel and dentin bonding.
7) Matrix placement.
8) Inserting the composite.
9) Contouring the composite.
10) polishing the composite.
STEPS IN COMPOSITE RESTORATION
As a general rule, similar to the tooth preparation for direct
anterior restorations, the tooth preparation for direct posterior
(1) creating access to the faulty Structure.
(2) removal of faulty structures (caries, defective
restoration and base material, if present).
(3) creating convenience form for the restoration. Retention is
obtained by bonding. When placing most posterior composites,
it is not necessary to incorporate mechanical retention features
in the tooth preparation.
Small to Moderate Class I Direct
Small to moderate Class I direct composite restorations may
use minimally invasive tooth preparations and do not require
typical resistance and retention form features. Instead, these
conservative preparations typically use more flared cavosurface
forms without uniform or flat pulpal or axial walls. These
preparations are less specific in form, having a scooped-out
appearance. They are prepared with a small round or elongated
pear diamond or bur with round features. The initial
pulpal depth is approximately 0.2 mm inside the DEJ but may
not be uniform (i.e., the pulpal floor is not flat throughout its
Small to Moderate Class I Direct
Moderate to Large Class I Direct
Moderate to large Class I direct composite restorations,
especially when used for larger caries lesions or to replace
existing defective amalgam restorations, will typically feature
flat walls that are perpendicular to occlusal forces, as well as
strong tooth and restoration marginal configurations. All of
these features help resist potential fracture in less conservative
tooth preparations. However, the preparation should never be
excessively extended beyond removal of faulty structures to
justify resistance and retention forms, as this will weaken the
tooth structure and can ultimately lead to failure of the tooth
restoration unit. If the occlusal portion of the restoration is
expected to be extensive, elongated pearl cutting instruments
with round features are preferred because they result in strong,
90-degree cavosurface margins. However, this box-like form
preparation may increase the negative effects of the
configuration factor (C-factor). (See the section on inserting and
light activating the composite for other considerations regarding
the C-factor for Class I direct composite restorations.) The
objective of the tooth preparation is to remove all of the caries or
fault as conservatively as possible. Because the composite is
bonded to the tooth structure, other less involved, or at-risk,
areas can be sealed as part of the conservative preparation
techniques. Sealants may be combined with the Class I composite
Small Class II Direct Composite Restorations
Small Class II direct composite restorations are often used for
primary caries lesions, that is, initial restorations. A small
round or elongated pearl diamond or bur with round features
may be used for this preparation to scoop out the carious or
faulty material from the occlusal and proximal surfaces. The
pulpal and axial depths are dictated only by the depth of the
lesion and are not uniform. The proximal extensions likewise
are dictated only by the extent of the lesion but may require
extended occlusally , facially, and gingivally enough to remove
the lesion. The axial depth is determined by the extent of the
lesion. The occlusal, facial, and gingival cavosurface margins are
90 degrees or greater. Care should be taken not to undermine
the marginal ridge during the preparation.
Moderate to Large Class II Direct
the tooth preparation for moderate to large class ii direct
composite restorations has features that resemble a more traditional
class ii amalgam tooth preparation and include an
occlusal step and a proximal box.
The occlusal portion of the Class II preparation is prepared
similarly as described for the Class I preparation. The primary
differences are related to technique of incorporating the faulty
proximal surface. Pre-operatively, the proposed facial and
lingual proximal extensions should be visualized . Initial occlusal
extension toward the involved proximal surface should go
through the marginal ridge area at initial pulpal floor depth,
exposing the DEJ. The DEJ serves as a guide for preparing the
proximal box portion of the preparation.
The pulpal floor is prepared with the instrument to a depth
that is approximately 0.2 mm inside the DEJ. The instrument
is moved to include caries and all defects facially or lingually
or both, as it transverses the central groove. Every effort should
be made, however, to keep the faciolingual width of the preparation
as narrow as possible. The initial depth is maintained
during the mesiodistal movement, but follows the rise and fall
of the underlying DEJ
Typically, caries develops on a proximal surface immediately
gingival to the proximal contact. The extent of the caries lesion
and amount of old restorative material are two factors that
dictate the facial, lingual, and gingival extensions of the proximal
box of the preparation. Although it is not required to
extend the proximal box beyond contact with the adjacent
tooth (i.e., provide clearance with the adjacent tooth), it may
simplify the preparation, matrix placement, and contouring
procedures. If all of the defect can be removed without extending
the proximal preparation beyond the contact, however, the
restoration of the proximal contact with the composite is
After the operator cleans the teeth, administers local anesthetic, selects the
shade of composite, and isolates the area, a wedge is placed in the gingival
embrasure .Early wedging helps in the separation of teeth, to compensate
later for the thickness of the matrix band, fulfilling one of several
requirements for a good proximal contact for the composite restoration.
The placement of a bitine ring preoperatively can achieve the same goal.
The lack of pressure against the matrix during placement of composite
compared with pressure of amalgam during its condensation dictates the
need not only for increased separation by early wedging but also the need
for operator alertness to verify matrix contact with the adjacent tooth
before composite placement. The wedge also depresses and protects the
rubber dam and gingival tissue when the proximal area is prepared. An
additional, further tightening (insertion) of the wedge during tooth
preparation may be helpful. The presence of the wedge during the
composite in these areas. Beveled composite margins also may be more
difficult to finish.
Mesio-occlusal (MO) Class II tooth preparation for posterior composite restoration in the
maxillary first premolar. A, Esthetic problem is caused by caries and existing amalgam
restoration. B, In this patient, the mesial marginal ridge is not a centric holding area. C, Early
wedging after rubber dam placement. D, An elongated pear bur or diamond is used for
initial tooth preparations on both premolars. E, After extensive caries is excavated, a calcium
hydroxide liner and a resin-modified glass ionomer (RMGI) base are inserted. F, Preparations
are completed, if necessary, by roughening the prepared tooth structure with diamond
Bevels are rarely used on any of the proximal box walls because of the
difficulty in restoring these areas, particularly when using inherently viscous
packable composites. Bevels also are not recommended along the gingival
margins of the proximal box; however, it is still necessary to remove any
unsupported enamel rods along the margins because of the gingival
orientation of the enamel rods. For most Class II preparations, this margin
already is approaching the cementoenamel junction (CEJ), and the enamel is
Factors can influence the clinical success of class
II composite restorations
composite composition–dentin bonding
The popularity and demand for resin-based
societal focus on aesthetics.
restorations placed in patients with high caries risk
have restoration failure rates two times than
those of patients with low caries risk.
the practitioner must give careful consideration to
the caries status of the patient and adjust
recommendations for restorative materials
resins are utilized to maximize aesthetics and
minimize the loss of tooth structure during
Due to the location of the caries and thus the
need to restore proximal surfaces in class II
restorations, a number of tooth preparation
designs have been advocated:_
Minibox or “slot” preparations
designs have been
described as minimally
invasive and relatively
successful with a
reported 70% success
rate over an average of 7
traditional preparation designs
designs, which involve
access through the carious
marginal ridge and the
removal of infected occlusal
enamel and dentin, may be
aesthetics deemed restoration
that clinicians should utilize posterior resin
composites in areas where aesthetics is
deemed essential and should maintain as
much tooth structure as possible.
aesthetics deemed restoration
the aesthetic results
obtained when replacing
a proximal amalgam
restoration with a resin-
One of the most important steps
in restoring Class II preparations
with direct composites is the selection and proper placement
of the matrix. In contrast to amalgam, which can be condensed to improve
the proximal contact, Class II composites are almost totally dependent on
the contour and position of the matrix for establishing appropriate proximal
Early wedging and re-tightening of the wedge during tooth preparation aid in
achieving sufficient separation of teeth to compensate for the thickness of
the matrix band. Before placing the composite material, the matrix band
must be in absolute contact with (touching) the adjacent contact area.
two basic types:
(1) metal matrices, which are straight or circumferential/ precontoured
(2) transparent matrices which are either straight or circumferential/
The influence of matrix type
Despite the theory that transparent matrices will
enhance polymerization at the gingival margin,
the recent literature suggests that the choice of
matrix does not influence the clinical success of
class II posterior resins.
Placement of the Adhesive
When using an etch-and-rinse adhesive,
over-drying the etched dentin can compromise dentin
bonding. Aqueous solutions containing glutaraldehyde
and 2-hydroxyethyl methacrylate (HEMA) can be used as a
re-wetting agent when using etch-and-rinse systems . The
bonding agent is applied to the entire preparation with a
Micro brush , in accordance with the manufacturer’s
After application, the adhesive is polymerized with a
light-activation unit, as recommended by the manufacturer
When the final tooth preparation is judged to be near the pulp in
vital teeth, the operator may elect to use a base material prior to
placing the adhesive and the composite. If the remaining dentin
thickness (RDT) is between 0.5 and 1.5 mm, a resin-modified
glass ionomer (RMGI) base is used; if the RDT is less than 0.5
mm, a calcium hydroxide liner should be applied to the deepest
aspect of the preparation, then protected with an RMGI base
prior to adhesive placement.
enamel and dentin bonding
The clinical success of enamel bonding with 37%
phosphoric acid led clinicians to take the same approach to
dentin bonding .however , the early dentin bonding systems
resulted in low bond strength.
Enamel is 95% inorganic matter( hydroxy –apatite). 4%
water, and 1% organic matter(a collagen substance called
enamelin)by weight. Although enamel is naturally
hydrophilic (readily absorbing water),hydrophobic(resist to
absorbing water) bonding resins can wet and penetrate
dried,etched enamel because of high surface energy of an
Dentin , on the other hand, is just 70% hydroxy apatite,18%
collagen ,and 12% water by weight.
This collagen is normally inaccessible, owing to surrounding
hydroxyapatite crystals. The only obvious “pores” available for resin
to penetrate are the dentin tubules , because of fluid flow from the
dentine tubules , dentin is more hydrophilic than enamel ,which
makes bonding a hydrophobic resin in to the dentin substrate
Dentine bonding is highly technique sensitive and can be highly
variable. Deep dentin exhibits far more tubules than superficial
dentin , but also shows lower bond strength partly because the
tubules are more fluid filled near the pulp . dentin fluids can
interfere with a resin-dentin bond.
Bond strength to all dentin surfaces are consistently lower than to
enamel, regardless of the material used or the presence or absence
of pulpal pressure.
Insertion and Light-Activation
of the Composite
A matrix is usually not necessary for Class I direct composite
restorations, even when facial and lingual surface grooves are
included. The composite should not be dispensed until it is
ready to use because it may begin to polymerize from the
ambient light in the operatory. Because of variations in materials,
each manufacturer’s specific instructions should be followed.
Composite insertion hand instruments or a compule may
be used to insert the composite material. The dispenser, for
example, a syringe or compule, must be kept covered when
not in use to prevent premature hardening of the material.
Small increments of composite material are added and successively
light-activated . It is important to place (and light-activate) the composite
incrementally to maximize the polymerization depth of cure and possibly to reduce
the negative effects of polymerization shrinkage.
Insertion and Light-Activation
of the Composite
the term “configuration factor” or “c-factor” has been used to describe the ratio
of bonded to unbonded surfaces in a tooth preparation and restoration. a typical
class i tooth preparation will have a high c-factor of 5 (five bonded surfaces—
pulpal, facial, lingual, mesial, and distal. one unbounded surface— occlusal). the
higher the c-factor of a tooth preparation, the higher the potential for composite
polymerization shrinkage stress, as the composite shrinkage deformation is
restricted by the bonded surfaces. Incremental insertion and light-activation of
the composite may reduce the negative c-factor effects for class i composite
the use of an rmgi liner or a flowable composite liner also may reduce the
effects of polymerization shrinkage stress because of their favorable elastic
modulus (more elastic material will more effectively absorb polymerization
stresses). when composite is placed over an rmgi material, this technique is
often referred to as a “sandwich” technique.
The potential advantages of this technique are:_
(1) the RMGI material bonds to the dentin without opening the dentinal
tubules, reducing the potential for post-operative sensitivity
(2) the RMGI material, because of its bond to dentin and
potential for fluoride release (potential anti- cariogenicity),
provides a better seal when used in cases where the preparation
extends gingivally onto root structure.
(3) the favorable elastic modulus of the RMGI reduces the effects of
polymerization shrinkage stresses. These suggested advantages
are considered controversial, as no published research
based on longitudinal clinical trials evaluating the technique
Flowable composites also are advocated as liners under
posterior composite restorations. The purported primary
advantage is that they may reduce some of the negative effects
of polymerization shrinkage because of their very favorable
When it is necessary to extend a composite restoration onto
the root surface, the use of an RMGI liner beneath the portion
of the restoration on the root surface may decrease
microleakage, gap formation, and recurrent caries.
Contouring and Polishing of the Composite
If the composite is carefully placed and shaped before light
activation, as described in the previous section, additional
contouring with burs is substantially minimized. However,
in many cases, refined contouring may be needed,
especially when occlusion adjustments are necessary.
The occlusal surface is shaped with a round or oval carbide
finishing bur or similarly shaped finishing diamonds.
Finishing is accomplished with appropriate polishing cups,
points, or both after the occlusion is adjusted as necessary.
Contouring and polishing of Class I composite. A, Mandibular molar with
old amalgam restoration. B, Rubber dam isolation; old restoration is carefully removed to
minimize increasing preparation size. C, Final tooth preparation. D, Incremental placement
E, Incremental placement of composite. F, Rubber dam is removed and
occlusion checked. G, Buccal view, a finishing fluted bur is used to selectively
adjust the occlusion. H, Polishing with brush and diamond paste. I, Completed
post-operative sensitivity used to go hand
in hand with the restoration of teeth.
this sensitivity is associated with the odontoblastic process and is most
commonly caused by inappropriate use of the dentin bonding agent. the pain
ranges from slight to acute. with amalgam, for example, sensitivity commonly
occurs immediately after placement and lasts for a week to 10 days.
during the first several days after restoration a definite gap of several microns
exists between the walls of the preparation and the amalgam restoration,
thereby allowing the transfer of fluids. the sensitivity associated with posterior
composites can last considerably longer and demonstrate appreciably greater
the mechanism of sensitivity is somewhat complex. regardless of the cause, the
pain can be directly related to the odontoblast itself. whatever creates a
negative pressure on the odontoblastic process creates a pain response.
Positive pressure has no effect; only negative pressure creates a response.
Postoperative Sensitivity and Restorative Imperatives
The extent of preparation should be dictated by the amount and location of sound
tooth structure present, with the clinician taking care to confine tooth reduction to
the elimination of carious tooth structures and creating a cavity design sufficient to
withstand the demands of the intraoral environment. Whenever possible,
preparations should remain in the enamel.
Bevel enamel margins to conceal the margin, Leaving the enamel margins
roughened will enhance bond strength as well.
Good bonding to prevent micro leakage.
The cavity design should feature rounded internal line angles to improve stress
distribution upon placement of the restorative materials through a
micromechanical adhesive approach.
Rubber dam isolation is recommended for proper moisture control at the
restorative site as well as to prevent bacterial or salivary contamination and to
reduce airborne debris.
Postoperative sensitivity causes patient discomfort that often predisposes him or
her for re-treatment and additional office time. Consequently, the ability of modern
adhesive dental approaches to eliminate this sequellae is a considerable benefit to
patient and practitioner alike.