12/3/2015
INDIRECT CAST GOLD INLAY & ONLAY
RESTORATIONS
Dr. Gaurav Garg ( M.D.S.)
Lecturer, College of Dentistry
Al Zulfi, Majmaah University
LEARNING OBJECTIVES
At the end of the lecture students should know:
 Indirect restorations & their types
 Indications, contraindications, advantages &
disadvantages of indirect restorations
 Materials used for indirect restorations & clinical
procedures
 Tooth preparation for cast gold inlay & onlay
restorations

INTRODUCTION

An indirect restoration is any restoration that is
fabricated extraorally and then cemented into/onto
the tooth.
Types:
A. Intracoronal
restorations that fit
within the contours of a
tooth (e.g. inlays, Onlays,
cast intra-radicular
posts)

A.
Inlay
Onlay
Extra-coronal
restorations that cover
the outer surface of a
tooth to recreate the
anatomic contours (e.g.
full or partial coverage
crowns, veneers)
Crown
INLAY

Inlay involves the occlusal (Class I) or occlusal
and proximal (Class II) surfaces of a posterior
tooth and may cap one or more, but not all of the
cusps.
ONLAY

Onlay involves the proximal surfaces (class II) of
a posterior tooth, and caps all of the cusps.
INDICATIONS

Large Restorations

Endodontically Treated Teeth

Teeth at Risk for Fracture


Diastema Closure and Occlusal Plane
Correction
Removable Prosthodontic Abutment
CONTRAINDICATIONS

High Caries Rate

Young Patients

Esthetics

Small Restorations
ADVANTAGES

High compressive & tensile strength

Biocompatibility

Low Wear

Control of Contours and Contacts
DISADVANTAGES

Multiple appointments and higher
Chairside Time

Costly

Technique sensitive

Splitting Forces:

Small inlays may produce a wedging effect on facial and/or
lingual tooth structure, and thereby increase the potential
for splitting the tooth
MATERIALS

Traditional high-gold alloys- Most suitable
for inlay & onlay (Costly-minimum total goldplus-platinum content of 75% by weight)

Low-gold alloys

Palladium-silver alloys

Base metal alloys ( Nickel chromium ,
Cobalt chromium, Cheaper)- Decreased tarnish
resistance, decreased burnishability & higher incidence of allergy
CLINICAL PROCEDURES

Evaluation of the occlusal contacts of the teeth
in centric & eccentric movements

Local Anaesthesia & isolation

Tooth preparation

Impression making

Temporization

Try in & occlusal adjustments

Cementation of the restoration
TOOTH PREPARATION FOR INLAY & ONLAY
FACTORS INFLUENCING THE DESIGN OF
THE CAVITY

Length of the clinical crown

Anatomic contours of the occlusal, Proximal, buccal
and lingual surfaces

Position of tooth in the arch

Occlusal and proximal relations

Unusual esthetic conditions, if any

Condition of soft tissues around the tooth

Extent and location of carious lesions.
INLAY
OUTLINE FORM


Include carious lesion and all
faulty pits and fissures &
cavosurface margin is to be
established on sound enamel
The depth of the cavity is
maintained at 1.75 - 2.0 mm from
the central groove

Consider Enameloplasty

Buccolingual width of cavity1/3rd of Intercuspal distance

Gingivally there should be a
clearence of 0.5 mm from
adjacent tooth
Burs for inlay/onlay preparation
RETENTION FORM







Primary retention:
Occlusal dovetail
Parallelism of buccal & lingual
walls: Occlusal divergence of
2º-3º. The divergence can be
increased up to 6º in case the
depth of cavity is more
Secondary retention:
Proximal slice
Slots
Shallow retentive grooves, 0.3
mm deep (0.2 mm inside DEJ),
may be given in the bucco-axial
and linguo-axial line angles
FACTORS AFFECTING RETENTION








Magnitude of dislodging forces
Geometry of the tooth preparation:
Taper : Decreased retention if taper is increased
Axial Depth: deep preparation provide more retention
Surface area: Retention increases with increase in surface
area of preparation
Roughness of the surfaces being cemented
Materials being cemented: The more reactive the alloy is,
the more will be adhesion with the luting cement. Therefore,
base metal alloys are better retained than less reactive high
gold alloys
Type of luting agent: Adhesive resin cements provide higher
retention than other cements.
RESISTANCE FORM

Flat pulpal and gingival floors

Rounded Axiopulpal line angle

Removal of unsupported enamel

Preserve cuspal strength


Cavosurface bevel- 40º- it creates obtuse angled marginal
tooth structure, which is bulkiest and strongest. Such type
of marginal tooth structure produce an acute angled (30º40º) marginal cast alloy, which can be easily burnished
Primary & Secondary flares
BEVEL

Types:

a. Partial bevel: It involves part of the enamel wall.
Given in direct composite restorations





b. Short bevel: It involves the entire enamel wall.
This type of preparation is best suited in cast gold
restorations.
c. Inverted bevel: It is given on the labial shoulder
of metal ceramic crowns to effectively improve the
esthetics at the margins.
d. Reverse Bevel: A reverse bevel is placed at the
dentinal portion of the gingival floor towards the axiogingival line angle.
The hydrostatic pressure during cementing a cast
restoration can produce a rotational displacement of
the castings with flat gingival walls.
This effect is resisted by the reverse bevel resulting in
even seating of the cast restoration.
(d)
No.8862 bur
FLARES







A. Primary Flare:
It involves divergence of the buccal and lingual
proximal walls at an angle of 45º
It bring the buccal and lingual proximal
margins of the cavity preparation in the
embrasures enabling easy cleaning and
finishing
B. Secondary flares:
Beveling the cavosurface wall peripheral to the
primary flare.
The direction of the secondary flare results in
40º marginal metal, which is burnishable and
produces good adaptation to the cavity margin.
In certain cases where the contact is broad and
wide, the secondary flares become mandatory
to bring the proximal walls in self-cleansing
embrasures.
B
A
ONLAY

Cuspal/occlusal reduction:
1.5 mm on functional cusp
1 mm on non functional cusp

Chamfer/Shoulder margin


REFERENCES & SUGGESTED READING
 Sturdevant's art & science of operative dentistry-2006-
Theodore M. Roberson, Harald O. Heymann, Edward J. Swift, Jr.
 Principles of operative dentistry (2005)- A.J.E. Qualtrough, J.D.
Satterthwaite, L.A. Morrow and P.A. Brunton.
 Fundamentals of Operative Dentistry- 2nd Edition- Summitt &
Robbins