class 2 inlay 1.pptx

CLASS-II
INLAY
B.Sai Madhuri
1st year MDS

CONTENTS
 Definition
 History
 Material for cast restoration
 Indication
 Contraindications
 Advantages
 Disadvantages
 Steps of tooth preparation
 Bevels and flares
 Modifications
 Inlay wax
 Impression techniques
 References

 Class II inlay involves the occlusal and proximal surfaces of a
posterior tooth and may cap one or more, but not all of the cusps
-Studevant, 7th ed
 A ﬁxed intracoronal restoration; a dental restoration made outside of
a tooth to correspond to the form of the prepared cavity, which is then
luted into the tooth.
- GPT 9
 Inlays are entirely intracoronal restorations, most commonly with
occlusal and proximal extensions
- summit 4th ed
 Inlays may be used as single-tooth restorations for proximo-occlusal
or gingival lesions with minimal to moderate extensions
-Shillingburg
Definitions

History
 Metal casting : Lost wax/ “Cire perdue” method
 Agiulhon de Saran in 1844: Inlay in investment mold with molten
Gold
 B.F. Philbrook: simplified version of casting process in 1897
 Porcelain inlays : 1857
later replaced by the cast gold inlays
 William Taggart in 1907: Technique of fabrication of gold castings
 Centrifugal casting machine : Jamieson in 1907
 1985: first ceramic inlay CAD/CAM
Schluein TM. Significant events in the history of Operative dentistry. Journal of History of Dentistry. Vol 53. No
2.2005.63-72

Material for cast restoration
 ADA Speciication No. 5
 Requires a minimum total gold plus-platinum-metals
content of 75 weight percent (wt%).
Acc to sturdevant four distinct groups of alloys are in
use for cast restorations:
(1) Traditional high-gold alloys,
(2) Low-gold alloys,
(3) Palladium–silver alloys, and
(4) Base metal alloy
. Studevant’s Art and science of operative dentistry – 7th edition

Acc to marzouk
Class I – Gold and Platinum based alloys
Class II- low gold alloys <50%
Class III- non Gold, Palladium based alloys
Class IV- Nickel-Chromium based alloys
Class V – Castable and moldable ceramics
Marzouk MA, Simonton AL, Gross RD. Operative Dentistry- Modern Theory & Practice, 1st Edition

 Type-I (Soft): For restorations subject to very slight
stress such as inlays.
 Type-II (Medium): For restorations subject to moderate
stress such as onlays.
 Type-III (Hard): For high-stress situations, including
onlays, crowns, thick veneer crowns and short-span
fixed partial dentures.
 Type-IV (Extra hard): For extremely high stress states,
such as endodontic posts and cores, thin veneer crowns,
long span fixed partial dentures and removable partial
dentures

Indication
 Large Restoration
 Endodontically Treated Teeth
 Teeth at risk for Fracture
 Removable Prosthodontic Abutment
 Dental rehabilitation with cast metal alloys
 Diastema closure and occlusal plane correction

Contraindications
 High caries rate
 Young patients
 Esthetics
 Small restorations

Advantages
 Strength
 Biocompatibility
 Low wear
 Control of contours and contacts

Disadvantages
 Number of Appointment and Higher Chair Time
 Temporary Restoration
 Cost
 Technique Sensitivity
 Splitting Force

Basic concepts of cavity design
 Inlay taper
 Bevels and Flares
 Variation in proximal design
Principles and practice of operative dentistry – Gearld T. Charbeneau – 3rd edition

Initial Procedure
 Occlusion
 Anesthesia
 Consideration for Temporary Restoration

Tooth Preparation for Class
II Cast- Metal
Restoration
 Initial Preparation

Occlusal Step

Proximal box

Inlay taper
 In extracoronal preparation walls must converge from the
cervical to the occlusal surface. This is the concept Of taper.
 Taper permits an unobstructed removal of the wax pattern &
seating of the subsequent casting.
 The taper is 2-5 degree from the path of preparation
 Each wall should make a right angle or slightly obtuse angle
with the pulpal floor.
 Longer preparations require taper in higher range, short
preparations in the lower range

 Extension of opposing walls, which diverge toward the
occlusal form a convergent angle ‘b’.
 A bisection of this angle positions the “line of draw”
which is perpendicular to the pulpal floor.

Final Preparation
Removal of Soft Dentin and Pulp Protection

 Bevels are the flexible extensions of a cavity
preparation, allowing the inclusion of surface defects,
supplementary grooves, or other areas on the tooth
surface.
 Beveling of enamel margins serve the following
purposes
1. Obtuse -angled tooth structure i.e. the
strongest configuration and acute-angled
marginal alloy i.e. burnishable. Thus makes
it possible to decrease the cement line.
2. A lap, sliding fit is produced at gingival
margin.
3. It results in 30- degree metal that is
burnishable.
4. Weak enamel is removed.

 Properly directed gingival bevel resulting in 30 degree
marginal metal
 Failing to bevel gingival margin resulting in
undermined rods and difficulty in burnishing
A cavosurface enamel angle of more
than 150 degrees is incorrect because
it results in a less defined enamel
margin (finish line), and the
marginal cast-metal alloy is too thin
and weak if its angle is less than 30
degrees. Conversely, if the enamel
margin is 140 degrees or less, the
metal is too bulky and difficult to
burnish when its angle is greater than
40 degrees

 Noy’s requirements
1. If preparation ends on enamel, the enamel must be
supported by sound dentin
2. Enamel rods forming the cavosurface margin should be
continuous with sound dentin & covered with restorative
material

Types of bevel
 Partial bevel
 Short bevel
 Long bevel
 Full bevel
 Hollow ground bevel
 Counter bevel

 Partial bevel
Involves the
part of the
enamel wall,
not
exceeding
2/3rd of its
dimensions.
 Not used in
cast
restorations
 Used to trim
weak enamel
rods from
margin
peripheries
Short bevel
Includes the
entire enamel
wall but not
dentin
 Long bevel
Includes all
of the enamel
wall & up to
one half of
the dentinal
wall.
 Advantage:
preserves the
internal
boxed up
resistance &
retention
features of
the
preparation
 Counter
bevel Given
opposite to
an axial wall,
on the facial
or lingual
surface with
the gingival
inclination
facially or
lingually.
 Used for the
capping of
cusps to
protect &
support them
`
 Full bevel
Includes all
of the
dentinal &
enamel
walls .
 Disadvantag
e: deprives
the
preparations
internal
resistance &
retention
form
Hollow
ground
(concave)
bevel
Prepared in
concave
form. It
allows more
space for
cast material
bulk

Flares
 Primary flare
 Secondary flare

Summit JB, Robbins JW, Schwartz RS. Fundamentals of Operative Dentistry. A Contemporary Approach. 2nd edition

Modifications of proximal box preparation
 Box preparation
 Slice preparation
 Auxiliary slice preparation
 Modified flare

Box preparation
 Introduced by Dr.G.V.Black
 Proximal cavities are box shaped.
 Advantages
• Resistence and retention form
• The outline form can be made on all types of teeth.
• Minimum display of metal.
 Disadvantages
• Involves removal of lot of tooth structure.
• Time consuming clinically.
• Narrow bevels leave a sharp edge and an undercut gingivally,
which cannot be reproduced satisfactorily.
• While taking impressions, distortions and breaking of wax
pattern occurs

Slice preparations
 This form of cavity is modified so that the proximal
surface is flat without definite side walls.
 Retention mainly depends upon occlusal key, locks cut in
the axial wall.
 Indications
 As abutment in bridge work.
 Teeth with proximal undercuts can
be eliminated which facilitates taking
impression.
 For indirect wax pattern technique.

 Advantages :
• Less tooth structure is sacrificed.
• Quicker and easier.
• Well protected enamel margins.
• Increase resistence and retention by exposing larger
amount of tooth structure.
 Disadvantages :
• It displays more amount of gold.
• Direct wax pattern cannot be made as distinguishing
between margins become difficult.
• Metal margins are likely to distort due to less thickness

CONTENTS
 Definition
 History
 Material for cast restoration
 Indication
 Contraindications
 Advantages
 Disadvantages
 Steps of tooth preparation
 Bevels and flares
 Modifications
 Inlay wax
 Wax pattern
 Sprue
 References

Auxiliary slice preparations
 Wraps partially around the proximal line angles,
thus providing additional support.
 Resistance form is enhanced
 Provide external retention form.

Modified flare preparation
 Modified flare is a combination of box preparation
and slice preparation.
 Minimum disking of proximal walls is done for
better finishing and polishing.

Modifications in Inlay Tooth Preparations
 Mesioocclusodistal Preparation
 Modifications of Class II Preparation for Esthetics

 Facial or Lingual Surface Groove Extension

 Class
II Preparation for Abutment Teeth and
Extension Gingivally to Include Root-Surface Lesion

 Maxillary First Molar With Unaffected, Strong Oblique
Ridge – also called as Tucker Technique

Auxillary retention forms
 Luting cement
 Reverse bevel
 Internal box
 Pins
 Collars
 Skirts
 Roughening of pulpal floor
 Electrolytic etching of inlay
Proximal & occlusal surface protected with wax
Kept in electrolyte solution of 0.5 normal nitric acid
Inlay-anode & metal with greater EMF cathode
Current causes microporosities and enables flow of luting cement for better
retention

Textbook of operative dentistry –Vimal K Sikiri - 4nd edition

Inlay wax
 ADA SP. NO. 4
 Types
1. Type I – medium wax – direct technique
2. Type II – soft wax – indirect technique
Anusavice, Shen, Rawls. Phillips’ Science of Dental Materials, 12th Edition

Composition
 Paraffin wax
 Ceresin
 Gum dammar
 Carnuaba wax
 Candelilla

Properties
 When softened, the wax should be uniform.
 Color should contrast with the die or tooth.
 No flakiness.
 No chipping.
 Completely vaporize during burnout.
 Completely rigid & dimensionally stable at all time

Flow:
 lacks rigidity, flows at room temperature
• type I – 1% at 37°C
• type I & II- 70-90% at 45°C
Coefficient of thermal expansion :
The rate of expansion of type 1 inlay wax is greatest from just
below mouth temp. to above 45 C

Impression techniques
Impression
technique
Direct
technique
Open method-
with matrix
band
Closed
method-
without matrix
Indirect
technique

PKT instruments
 No. 1 and no. 2 are wax addition instruments
 No. 3 is a burnisher for refining occlusal anatomy
 Nos. 4 and 5 are wax carvers.
Waxing Techniques to Develop Proper Occlusal Morphology in Different Occlusal Schemes J Indian Prosthodont Soc
(Oct-Dec 2011) 11(4):205–209.

Direct technique
Tissue compatible lubricant is placed
in the internal surface of the prepared
tooth and adjacent tooth
Piece of wax is placed on band and is flamed to
achieve hanging drop and band is immediately
place on tooth and pushed 2-3mm cervically
The wax is added PKT no1 or no 2.
Whenever subsequent layers of wax are added the
previous layer which was applied should be
remelted or else creases or folds would form on
fitting surface
Adequate bulk should be provided at proximal and
axial surface in order to prevent distortion while
removal
Waxing Techniques to Develop Proper Occlusal Morphology in Different Occlusal Schemes J Indian Prosthodont Soc
(Oct-Dec 2011) 11(4):205–209.

Finger pressure is maintained while the wax is cooled
and hardened
The bulk of excess wax is then trimmed using PKT 3,4 &
5. A moistened cotton is firmly placed on occlusal surface
to stabilize the pattern during carving
Matrix Retainer is loosened and removed Wax is held
firmly in place and band is removed
A narrow strip of copper ribbon is bent into a ‘V’ or ‘U’
shape, heated over the flame and quickly inserted as a
staple into the marginal ridge areas of the wax pattern
THE PATTERN IS CAREFULLY INSPECTED FOR:
Sharp internal details
Good reproduction of the cavosurface and gingival
margins

The pattern is again seated in the cavity. A
heated instrument is held lightly against the
copper staple, thus facilitating its removal
Pattern is then carved. Prepared tooth & opposing tooth is
isolated and dried with cotton rolls. With camel hair brush,
talcum powder is dusted on the occlusal surface of the wax
and the patient is instructed to close the teeth lightly
Cuspal contact with the wax pattern is
indicated by a shiny burnished spot on the
pattern. The spots of hyperocclusion are carved
away using warm carvers

Direct technique – without matrix band
 Simple conservative preparation of class 2
Contraindicated- no adjacent teeth
preparation with deep cervical floor
most of class 3,4 &5

Disadvantages
 Great skill & patience is required
 Greater tendency for wax pattern to get distorted.
 Indirect vision is required.
 Discrepancies at the gingival margin is difficult to
detect
 If the casting fails patient has to be recalled

Indirect method
 Wax pattern is made on the die.
 Type -2 inlay wax.
 More commonly used technique
Disadvantages
 The model may not be the exact replica of the tooth.
 Time consuming procedure.

The double-inlay technique
Use of both materials ( gold + ceramics) to add the
strength of metal to the esthetics of ceramic.

Sprue
Sprue former, or sprue pin, is to provide a channel through
which molten alloy can reach the mold in an invested ring
after the wax has been eliminated.
A sprue former can be made up of
Wax
Plastic
Metal
Diameter and length depend
 Type and size of the pattern
 Type of casting machine and
 Dimensions of the flask or ring

Wax pattern removal
Sprue former attached to the wax pattern on the master die
provided that the pattern can be removed directly in line
with its path of withdrawal from the die.
Sprue diameter
Same size as the thickest area of the wax pattern
 large sprue former to a thin, delicate pattern could cause
distortion
 Small sprue former solidify before the casting itself
localized shrinkage porosity (“suck-back” porosity)

Sprue position
 Proximal wall or just below a nonfunctional cusp to
minimize subsequent grinding of occlusal anatomy
and contact areas
 Ideal area for the sprue former is the point of
greatest bulk in the pattern to avoid distorting thin
areas of wax during attachment to the pattern

Sprue attachment
The sprue former connection to the wax pattern is
generally flared for high-density gold alloys but often
restricted for lower-density alloys
 Function – same as reservoir
Direct spruing - The sprue former provides a direct
connection between the pattern area and the sprue base.
Indirect spruing - A connector or reservoir bar is
positioned between the pattern and the crucible former

Sprue direction –
 Should be directed away from any thin or delicate
parts of the pattern
 Sprued at a 45° angle to the proximal area
 Should not be attached to a broad flat surface at a
right angle – causes turbulence within the mold
cavity and severe porosity

Sprue length
Depends on the length of the casting ring
Sprue length should be adjusted so that the top of the wax
pattern is within
6 mm of the open end of the ring for gypsum-bonded investments
3mm - higher-strength phosphatebonded investments
too short, the wax pattern – incomplete elimination of gases -
porosities

Causes of gold inlay failures are
(1) recurrent caries,
(2) periodontal breakdown,
(3) sensitive teeth,
(4) tooth fracture,
(5) poor esthetics, and
(6) loss of retention.
Fayle, H. E. (1973). Gold inlay failures and some causes. The Journal of Prosthetic Dentistry, 29(4), 439–441.

Conclusion
Cast restorations form an integral link in the dental
restorative chain. They are an excellent choice in
many demanding situations. Understanding the
principles of tooth preparations and the intricacies of
cast restorations will enable the dentist to optimally
utilize this excellent option when the clinical
situation demands.

 Studevant’s Art and science of operative dentistry – 7th edition
 Schluein TM. Significant events in the history of Operative dentistry.
Journal of History of Dentistry. Vol 53. No 2.2005.63-72
 Marzouk MA, Simonton AL, Gross RD. Operative Dentistry- Modern
Theory & Practice, 1st Edition
 Principles and practice of operative dentistry – Gearld T. Charbeneau –
3rd edition
 Anusavice, Shen, Rawls. Phillips’ Science of Dental Materials, 12th
Edition
 Summit JB, Robbins JW, Schwartz RS. Fundamentals of Operative
Dentistry. A Contemporary Approach. 2nd edition
 Waxing Techniques to Develop Proper Occlusal Morphology in
Different Occlusal Schemes J Indian Prosthodont Soc (Oct-Dec 2011)
11(4):205–209.
 Textbook of operative dentistry –Vimal K Sikiri - 4nd edition
 GPT-9

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