Indirect restorations in dentistry. seminar using combination of some of the most comprehensive articles giving an insight on preparation and bonding of partially bonded restorations

1. PARTIAL BONDED
RESTORATIONS AND ITS
ADHESION
Dr Pranita Gandhi
III MDS

2. CONTENTS
1. Introduction
2. Various Partial Bonded Restorations
3. Composites vs Ceramics
4. An overview of Dental Ceramics
5. Indications for PIARS
6. Cavity Design
7. Adhesive Posts: A controversy
8. Types of Preparation
9. Immediate Dentin Sealing
10. Adhesion of Restoration
11. Case Report
12. Conclusion
13. References

3. Introduction
With the development of dental materials over a
long time and efforts being made in developing the
properties of the materials to imitate the natural
tooth structure
Conservative treatments involve methods that
lessen the elimination of sound tooth structure and
establish the margin of the restoration at the
supragingival level.

4. In an extensively damaged tooth - Indirect partial coverage restorative techniques have
lately gained acceptance. It maintains the structure of the tooth along with repairing the
damaged parts to enable correction and re-establishing functioning of the tooth with a
better appearance.
The traditional preparation has harmful effects on periodontal conditions due to over-
contouring and overhangs of ceramic restoration, hence a new technique was suggested
to evaluate the quality as well as durability of restorations with a partial bonding
technique

5. Restorative procedures, like caries excavation, cavity preparation or endodontic
treatment, are accompanied by the reduction of tooth stability, a decrease of fracture
resistance, and an increase in deflection of weakened cusps.
The choice between a direct or an indirect restorative technique, mainly in posterior
areas, is a challenge, and involves biomechanical, anatomical, esthetic, and financial
considerations

6. VARIOUS PARTIAL BONDED
RESTORATIONS
ONALYS/OVERLAYS
VENEERS TABLE TOPS
INLAYS VENEERLAYS

7. (1)Porcelain Veneers
These are a thin piece of porcelain designed in a way giving a subtle
appearance of the teeth
This is a classical treatment option in comparison to the full-coverage
crown.
These veneers can change the color of the tooth, shape of damaged
tooth, or tooth surface structure. Porcelain veneers can change the
position of teeth involving closure of spaces between teeth.
These veneers are a type of retention less restoration that is hold in
place by adhesion only.

8. (2) Non-prep veneers (Lumineers):
Lumineers are thinner in comparison to veneers and require less preparation to be applied to
the teeth.
Potentially reversible and they don’t last as long as veneers, not as effective at masking
severely stained or discolored teeth.
The first appointment will be shorter because it doesn’t require trimming or prepping the
teeth.
Unlike veneers, Lumineers are semipermanent. After application, they can be removed with
minimal damage to your teeth.

9. 3. Inlay:
When decayed tooth surface area is too big to be filled then an inlay can be an
alternative way.
Inlays cover the central part of the tooth which includes the region between the
cusps and are placed enclosed by the hard tissues of the tooth.
Inlays do not cover the cusps. Hence, they are shaped accordingly so that they fit
perfectly on the teeth which restricts the residue from entering the covered decayed
tooth areas to aggravate further decay

10. 4. Onlay
Onlay can be used as a treating modality as it can cover one or more cusps
of the tooth.
In comparison to inlay, onlay can cover more areas, while they are also placed
inside the deep tissues of the tooth, onlay also covers part of the biting
surface of the tooth.
Onlays can go over the cusp (or cusps) of the tooth, while inlays can only
cover the space between the cusps.
Onlays are intermediate between filling a cavity and cutting tooth structure
to cap it with a crown.

11. 5. Overlay:
An overlay is a prosthesis that tends to restore the occlusal cusp integrity of a tooth. It
crosses beyond the occlusal table in cervical direction and it has been also called a
partial covering crown.
The term itself depicts the peripheral limits mainly, which when compared to the
classical crown is kept supragingival.
6. Veneerlay:
Veneerlays are type of overlay restorations.
It varies in the size of occlusal coverage, thickness, and peripheral coverage. More
conservative in nature for the tissues as it is more dependent on the occlusal table
thickness, veneerlay combines two “Anglo-Saxon” terms veneer and overlay.
It includes back tooth region Ceramic Bonded Restorations, which restore the
vestibular surface and the occlusal table

12. 7.Table top:
Tabletops are onlay restorations, they are also called occlusal veneers and are commonly used in cases of
wear of a large number of occlusal surfaces of posterior teeth.
They are a clinical variety of overlay which is basically a partial bonded restoration that mainly covers the
entire cusps.
Before treatment, it is necessary to do a diagnostic wax-up to plan the appropriate height that the
tabletops should have, as well as their function and aesthetics.

13. COMPOSITES OR
CERAMICS?
Since endodontically treated teeth are highly
susceptible to fracture, the decision regarding the
most suitable restorative material and technique is
even more difficult.

14. Short- comings of Composites
• Time consuming and cannot offer a long-term prognosis
• Shrinkage stress that occurs during polymerization, which may cause marginal leakage
and secondary caries.
• Occlusal wear of direct composite resin restorations may be a concern for large cavities or
for patients with parafunctional habits
• Fracture of direct composite resin restorations with cuspal coverage leads to more
dramatic failures
American Dental Association (ADA) statements regarding posterior, resin- based
composites (1998) suggest the use of direct restorations in small lesions and low
stress-bearing areas, and suggest they should be avoided in extended lesions, high-
stress areas, or when rubber dam cannot be placed.

15. Why ceramics could be a better option?
• It has been shown that light-cured indirect restorations with a cement thickness < 200 μm
generated less contraction stress than light-cured direct composite restorations
• Allows practitioner to achieve long lasting and excellent shade match
• Bonded ceramic restorations (eg, ceramic inlays or onlays and partial ceramic crowns) are a
clinically acceptable means of restoring extensively destroyed teeth.
• Preserve and strengthen compromised tooth structure, while taking advantage of the
mechanical benefits of modern adhesive technology and ceramics
• The use of adhesive techniques permits more conservative preparation designs

16. AN OVERVIEW OF
DENTAL CERAMICS

17. Ceramics were first used to fabricate porcelain denture teeth in late 1700s
Charles H Land - fabricated first ceramic crown
1980s - concept of acid etching porcelain to use resin based materials for
luting was developed
Successively- Glass infiltrated alumina (In Ceram) and Pressed Glass
ceramic restoration (Empress) were introduced
Nowadays- high strength ceramic materials – LiDiSi/ glass reinforced
ceramics or alternatively, high strength ceramic core materials veneered
with a translucent esthetic feldspathic ceramic are commonly used.

18. Ceramics are classified into two groups
ETCHABLE
Leucite reinforced
feldspathic and LiDiSi
crowns
Surface topography is
increased – selective
dissolution – HF acid
NON- ETCHABLE
Glass infiltrated alumina/
zirconia, densely sintered
alumina
Surface topography does
not change

19. INDICATIONS FOR PIARs
(Posterior Indirect Adhesive Restorations)

21. CAVITY DESIGN

22. Finite element modelling suggests:
Composite restored teeth
exhibit increased coronal
flexure
Ceramic inlays result in
increased coronal rigidity
Indirect composite restorations with a low modulus of elasticity exhibit increased
tension at the dentin-adhesive interface, suggesting that porcelain restorations have
a lower risk of debonding.

23. The cavity design for all-ceramic partial restorations requires the simplest possible basic geometry.
In fact, due to adhesive bonding technology, a retentive shape of the preparation is not necessary.
1.5 mm of pulpal depth starting from the
base of the development sulcus
rounded internal line angles
10 to 12 degrees of axial wall convergence
10 degrees or more of divergence on
buccal and lingual walls

24. 1 to 1.5 mm of axial wall reduction
90 degree cavosurface margins
2 mm isthmus width
2 mm occlusal reduction for cuspal
coverage
smooth flowing margins

25. Preparation margins - Supragingival
Are preferred for adhesive bonding
Recommended for caries prevention and for
periodontal reasons
Easier to prepare the cavity, to take the impression, to place rubber dam, to
enable visual control of the marginal seal, and to remove excess cement.
The quality of the marginal seal is better when
evaluated during follow- up

26. Analysis and choice of preparation.
The preparation should be made with clean cavities,
without residual decay or previous restorations.
Occlusal preparation
One of the first steps is the creation of occlusal grooves to
determine the height of the preparation (see Fig 7)
This can be done using different types of burs such as
rounded diamond burs or tapered burs

27. The thicknesses to maintain vary, depending mainly on the restorative material being used:
2 mm is a secure thickness in the case of layered composite, although it may be slightly
lower.
A thickness of 1 mm is suitable for monolithic restorations, ceramic materials such as
lithium disilicate, and resin-based materials reinforced with ceramic, which in
conditions of normal masticatory loads could be used up to a thickness of 0.5 mm.
A thickness of between 1.0 and 1.5 mm is considered safer in order to avoid clinical
complications, even for a high-resistance glass

28. Build -up
There are various advantages to the basic preventive reconstruction (the build-up or block out),
which is carried out before proceeding with the definitive preparation:
• The block out of the undercuts, filling the areas in which the indirect restoration would not find a
favorable morphology to the substrate.
‘
• Immediate hybridization of the dentin, known as immediate dentin sealing (IDS), especially
when the exposed dentinal area is wide, thermal situations that can occur, from the impression
taking to the adhesive cementation.
• Being able to determine the thickness of the future restoration

29. A controversial question is raised by the presence of an adhesive post (eg, fiberglass) inside
non-vital teeth
Some studies in the literature have shown how the presence of a post, including a fiberglass
one, as the core of a full-coronal coverage restoration increases the risk of fracture of the
tooth-restoration complex, compared to the composite material build-up without a post.
Adhesive Posts : A controversy
The presence of a post for the purpose of anchorage does not exist in the PIAR protocol, as
this type of restoration mainly exploits the adhesive bond resulting from the low-retention
design of the preparation.

30. A simple build-up without post is often suggested (Fig 6)
for the PIAR.
However, according to the adhesthetics protocol,
adhesive fiber posts are not contraindicated, for instance,
in the case of a vast lack of some dental walls, or when it
is thought that in future a prosthetic crown
could be made on the same element.

31. TYPES OF PREPARATIONS

32. The PIAR can be applied to various needs and different clinical goals.
There is no clear classification in the literature for the different types of preparation; therefore,
a classification is presented here on the basis of clinical experience
In the case of
posterior
onlays/overlay,
protocol:
• butt joint,
• bevel, and
• shoulder.
A Veneerlay
preparation may be
used in the case of
cuspal and buccal
coverage.
For tabletop on a
worn dentition, the
recommended
preparation is an
ultraconservative
butt joint with a
simple
surface finishing.

33. BUTT-JOINT
The butt joint requires minimal preparation and is therefore
suitable for adhesive techniques.
It is represented by an occlusal reduction that follows the
evolution of the cusps and the main sulcus, so is generally flat
but with an inclined surface.
At the level of the finishing line, the butt joint should have an
inclined trend toward and follow the occlusal surface, which is
then made more horizontal.

34. Indications for a butt joint preparation:
■ Cuspal reduction to protect the teeth from the
occlusal load
.■Cuspal fracture in the area of the occlusal third
(or middle third, in some cases).
■ Presence of strong abrasions/erosions of the
occlusal surface (with the possibility of increasing
the vertical dimension).

35. Considerations for cuspal coverage
Generally, if the cuspal thick- ness of the vital tooth (measured at the thinnest point and in axis with the cuspal
apex) is < 2 mm, a cuspal coverage is suggested.
For non-vital posterior teeth, the thickness limit is 3 mm
The non- functional thin cusps (with a thickness less than the aforementioned values) can be even more fragile,
and special attention must be paid to them.

36. Bevel Preparation
Similar to the butt joint but with the substantial difference of the
presence of an inclined bevel, generally of 45 degrees or more,
for an average length of 1 to 1.5 mm, which can be more
extended in exceptional cases.
This beveling is generally present on the buccal side, but can also
be on the palatal side
Where there is a bevel on the whole circumference, the variant of
a full bevel can be considered.

37. 0

38. Indications:
• Esthetic need for a more gradual integration of the restoration-tooth transition.
• Wider surface of external enamel, which enhances adhesive cementation procedures
• To create more space for the restoration in the peripheral zone

39. Shoulder preparation
Characterised by a rounded shoulder peripherally.
The thickness of the shoulder is about 1 mm, thus allowing for the largest
possible enamel..
The management of the finishing line must be realized with a geometrically
determined bur, with a slightly tapered shape and a rounded inner corner.
If the bur head diameter is 1 mm, it should be sunk to the entire thickness
of the substrates to be prepared, but if it is larger, it should not be
completely sunk.

40. Indications
• Previous cuspal fracture to the cervical third (or medium third in some cases), and then, by effect,
the central build-up automatically defines the peripheral shoulder design (Figs 17 to 20).

41. • Where a greater structural protection is required for cusp coverage with a cervical grasp.

42. PROXIMAL PREPARATION
DESIGNS
Slot
Bevel
Ridge up

43. Slot
a frequent interproximal preparation is represented by this design,
which has a rounded shoulder
(coherent with the shoulder preparation), generally of about 1 mm
(Fig 21).
One reason for this preparation being so widespread is because this
type of shoulder is naturally determined after the excavation of an
interproximal carious lesion, allowing for the creation of a central
reconstruction to the dental crown.

44. Bevel
A less invasive preparation compared with the slot for restoring the
interproximal area without going in too deeply at the cervical level.
This configuration offers some advantages for a bevel preparation
(Fig 22), such as a good surface of enamel, which enhances the
adhesive cementation procedure.
This preparation is indicated when an extensive restoration needs to
be made to the interproximal area without a previous carious lesion,
and localized cervically compared to the contact area.

45. Ridge up
Variant of this approach allows for the maintenance of the
integrity of the marginal ridge (Fig 23),
whereas the ridge coverage variant allows for minimal
surface preparation (Fig 24),
Given that the ridge is one of the most important
structural elements with regard to the integrity of the
non-vital tooth, in cases of reduced thickness of the
adjacent cusps one can opt for a cuspal coverage with the
preservation of the ridge.

46. The indication for this type of preparation is a cuspal coverage with the purpose of structural protection,
but with a good integrity of the ridge and the absence of cavitated carious lesions (Figs 25 to 29).

47. IMMEDIATE DENTIN SEALING
(IDS)

48. Whenever a substantial accessible area of dentin has been exposed during tooth preparation
for indirect bonded restorations, local application of a dentin bonding agent (DBA) is
recommended.
It is based on the principle of which is to create an interphase or interdiffusion layer, also called
the hybrid layer, by the interpenetration of monomers into the hard tissues
There are basic principles to be respected during the clinical procedure of dentin-resin
hybridization, the most important of which are related to problems of
(1) dentin contamination and
(2) susceptibility of the hybrid layer to collapse until it is polymerized.

49. There are at least four rational motives and several other practical and technical reasons
supporting IDS.
1. Freshly cut dentin is the ideal substrate for dentin bonding and in practice, freshly cut
dentin is present only at the time of tooth preparation (before impression).
2. Precuring of the DBA leads to improved bond strength. In most studies on DBA bond
strength, the infiltrating resin and adhesive layer are usually polymerized first (precuring),
before composite increments are placed, which appears to generate improved bond
strength when compared with samples in which DBA and the overlaying composite are
cured together

50. 3. Immediate dentin sealing allows stress-free dentin bond development. Dentin bond
strength develops progressively over time, probably owing to the completion of the
copolymerization process involving the different monomers. Reis and colleagues showed
significant increases in bond strength over a period of 1 week.
4. Immediate dentin sealing protects dentin against bacterial leakage and sensitivity
during provisionalization. Based on the fact that provisional restorations may permit
microleakage of bacteria and subsequently dentin sensitivity, in 1992 Pashley and colleagues
proposed sealing dentin in crown preparations.

51. Practical and Clinical Facts Supporting IDS
1. Patient comfort.
2. Maximum tooth structure preservation
3. Systematic use of light-activated DBA.
4. Separate conditioning of enamel and dentin.- “wet bonding” to dentin

52. PRACTICAL CONSIDERATIONS
Dentin Identification
The first technical step for the application of IDS is the identification of exposed dentin surfaces.
A simple but efficient method is to proceed to a short etching (2–3 s) and thorough drying of the
prepared surfaces. Dentin can be easily recognized because of its glossy aspect, whereas enamel is frosty.
Preparation Depth
As mentioned earlier, DBA thicknesses can reach several hundred micrometers when applied to concave
areas. When using IDS, the additional adhesive layer can sometimes negatively affect the thickness of the
future restoration. This is particularly evident in the case of porcelain veneers and in the presence of
gingival margins in dentin

53. IDS is not indicated for very superficial dentin exposures.
On the other hand, deeper preparation surfaces (ie, in the
presence of Class IV or V defects or in the case of inlay/onlay/
overlay preparations) can be easily treated with IDS before
impression taking
When margins terminate in dentin, a marked chamfer (0.7–0.8 mm)
is recommended to provide adequate margin definition and
enough space for the adhesive and overlaying restoration

54. Adhesive Technique
The technique described focuses on the use of the total-etch technique (also called “etch and rinse”),
which can include either three-step (separated primer and resin) or two-step (self-priming resin) dentin
adhesives.
Although there is a tendency to simplify bonding procedures, recent data confirm that conventional
three-step total-etch adhesives still perform most favorably and are most reliable in the long term.

55. Etching of the freshly cut dentin (with H3PO4 for 5–15 s) must immediately follow tooth
preparation to avoid saliva contamination.
Following rinsing, excess water must be removed. Can be achieved by use of suction drying
(negative air pressure)
The next steps can include the application of either the primer (three-step systems) or the self
priming resin (two-step systems).

56. Following a first curing (regular mode 20 s; see Figure 2 P), a layer of glycerin jelly (air block) is
applied to the adhesive and slightly beyond.
Additional curing (regular mode 10 s) of the DBA through a layer of glycerin jelly is
recommended (see Figure 2Q) to polymerize the oxygen inhibition layer and prevent interaction
of the dentin adhesive with the impression material (especially polyethers).

57. Adhesive Resins: Final Restoration Placement
Among the most reliable contemporary systems, OptiBond FL (Kerr, Orange, CA, USA) is
particularly indicated for the application of IDS because
ability to form a
consistent and
uniform layer
(about 80 µm
cohesiveness with the
final luting composite

58. Just prior to the luting procedures (when placing the final restoration), it is recommended to
roughen the existing adhesive resin using a coarse diamond bur at low speed or by micro
sandblasting.
The entire tooth preparation surface can then be conditioned as it would be done in the
absence of dentin exposure: H3PO4 etch (30 s), rinse, dry, and coat with adhesive resin.
This time, no precuring of the adhesive is indicated because it would prevent the complete
insertion of the restoration.

59. IDS can be immediately followed by the placement of a base of composite to block eventual
undercuts and/or to build up excessively deep cavities cation procedure for dentin bonding
when placing indirect bonded restorations such as composite/ ceramic inlays, onlays, and
veneers.
Immediate application and polymerization of the DBA to the freshly cut dentin, prior to
impression taking, is recommended.
The IDS appears to achieve improved bond strength, fewer gap formations, decreased bacterial
leakage, and reduced dentin sensitivity.

60. Presence of substrates favourable to adhesion
According to the adhesthetics protocol, the two best substrates for adhesive cementation are
enamel and composite build-up (or block out), which allow for a wider
hybridization and overcoating of the dentin substrate immediately after the cleansing of the
cavity.
These two substrates can be adequately prepared for adhesive procedures, bearing in mind
that the best guarantee of a restoration's resistance is a completely enamel preparation.

61. Following cavity preparation  IDS
 an impression is taken using
polyether impression material 
sent to a lab for fabrication
This is followed by placement of a
temporary restoration to protect
remaining tooth and to avoid
unwanted extrusion and movement
of tooth.

62. Adhesion of the Restoration

63. First, temporary restoration is removed and prosthesis is checked for interproximal contacts
After anaesthesia and rubber dam placement, entire preparation is decontaminated with
glycine and gently sandblasted with alumina
Prepared tooth is etched with 38% phosphoric acid for 20 s, rinsed and dried
Bonding agent applied over entire surface and left uncured
On the tooth surface

64. On the restoration
5 or 10% HF acid applied on the intaglio surface for 20 seconds
After rinsing and etching, silane coupling agent was applied and
solvent was evaporated with air spray.- 60 seconds
A layer of uncured bonding agent was applied and restorative
composite resin was applied on the tooth surface followed by
insertion of the restoration

65. After an accurate removal of resin excess, two high-power light-curing units were applied both
buccally, and lingually for at least 20s
A layer of glycerin gel was applied to eliminate the unreacted, exposed superficial composite at
the overlay tooth margin.
Dental floss was used to remove the interproximal composite debris, then polymerization
procedures and finishing took place with diamond red ring metal strips.
The restoration--tooth complex was then glossed with a Sof-Lex plastic strip, and polished
with a rubber point

66. After rubber dam removal, occlusal checks were performed with articulating papers.
Undesired occlusal adjustments were accurately re-polished with a rubber point or disc for
ceramic use.

67. The retention of the lithium silicate ceramic veneer can be satisfactorily achieved by two
factors: ceramic surface treatment from acid etching, and silane coupling agent application
prior to cementation with a resin cement.
In general, the structure of veneering ceramic has been described as an amorphous and glass
matrix that consists of a random network of cross-linked silica in a tetrahedral arrangement,
which is embedded in varying amounts of undissolved feldspar and reinforcement crystals like
lithium disilicate
Effect of hydrofluoric acid etching of a lithium disilicate-based glass ceramic

68. For ceramic surface treatment, the acid reacts with the glass matrix that contains silica and
forms hexafluorosilicates. This glass matrix is selectively removed and the crystalline structure
is exposed.
As a result, the surface of the ceramic becomes rough, which is expected for micromechanical
retention on the ceramic surface. This roughly etched surface also helps to provide more
surface energy prior to combining with the silane solution

69. Regarding the etching time, many studies have been done with different kinds of ceramics and
HF etchants.
Chen et al. evaluated two HF etchants (2.5 and 5%) and seven different etching times (0, 30,
60, 90, 120, 150, and 180 s). Etching periods above 30 s effectively enhanced the bond
strength to resin.

70. Case Report 1:
Failing amalgam restorations were evident on the first and second mandibular left molars, and recurrent decay with
multiple stained fracture lines was noted (Fig 6). Wear facets and enamel cracks were present in all the occlusal
surfaces (Figs 7 and 8). Radiographic evaluation revealed deep existing restorations with no periapical translucency
or other path-ologic findings. The patient was asymptomatic in both teeth, and an e.max pressed restoration was
planned on the first molar. The amount of recurrent decay (Fig 9) and the location of fractures (Figs 10 and
11)'made necessary the prophylactic removal of all weakened or undermined cusps (Fig 12).

74. Case Report 2:

76. Partial bonded restorations are a type of minimally
invasive treatment. As it can fully enact the properties of
the natural tooth form, while also delivering a good
aesthetic emergence which is one of the major worries of
the needful person.
The natural tooth form is much better than any artificial or
manufactured material hence effort is always made to
retain the most of the natural tooth in any kind of
restorative procedure.
While saving the natural tooth structure, it is also
important to reconstruct the tooth to make sure full
mechanical functioning and stability are present while also
getting a natural and pleasing cosmetic look.
CONCLUSION

77. References
1. Posterior indirect adhesive restorations (PIAR):
Preparation designs and adhesthetics clinical protocol –
Federico Ferraris. IJED
2. The use of bonded partial ceramic restorations to recover
heavily compromised teeth – Gianfranco Politano et al.
IEJD
3. Immediate Dentin Sealing: A Fundamental Procedure for
Indirect Bonded Restorations PASCAL MAGNE. J Esthet
Restor Dent
4. Partially Bonded Restorations Sarojini Biswal. Bulletin of
Environment, Pharmacology and Life Sciences
5. Bonded indirect restorations for posterior teeth: From
cavity preparation to provisionalization Giovanni
Tommaso Rocca. QUINTESSENCE INTERNATIONAL