1. Indirect Cast gold inlay & Onlay restorations
12/3/2015
Indirect Cast gold inlay & Onlay restorations
Dr. Gaurav Garg ( M.D.S.)
Lecturer, College of Dentistry
Al Zulfi, Majmaah University

2. 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

3. Introduction
An indirect restoration is any restoration that is fabricated extraorally and then cemented into/onto the tooth.

4. Types:
Intracoronal restorations that fit within the contours of a tooth (e.g. inlays, Onlays, cast intra-radicular posts)
Extra-coronal restorations that cover the outer surface of a tooth to recreate the anatomic contours (e.g. full or partial coverage crowns, veneers)
Inlay
Onlay
Crown

5. 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.

6. Onlay
Onlay involves the proximal surfaces (class II) of a posterior tooth, and caps all of the cusps.

7. Indications Large Restorations Endodontically Treated Teeth
Teeth at Risk for Fracture
Diastema Closure and Occlusal Plane Correction
Removable Prosthodontic Abutment

8. Contraindications High Caries Rate Young Patients Esthetics
Small Restorations

9. advantages High compressive & tensile strength Biocompatibility
Low Wear
Control of Contours and Contacts

10. 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

11. Materials
Traditional high-gold alloys- Most suitable for inlay & onlay (Costly-minimum total gold- plus-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

12. 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

13. Tooth preparation for inlay & onlay

14. 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.

15. 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 mm from the central groove
Consider Enameloplasty
Buccolingual width of cavity- 1/3rd of Intercuspal distance
Gingivally there should be a clearence of 0.5 mm from adjacent tooth
Burs for inlay/onlay preparation

18. 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

19. 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.

20. 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 (30º- 40º) marginal cast alloy, which can be easily burnished
Primary & Secondary flares

21. 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 axio- gingival 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)

22. No.8862 bur

23. 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

25. ONLAY Cuspal/occlusal reduction: 1.5 mm on functional cusp
1 mm on non functional cusp
Chamfer/Shoulder margin

28. References & Suggested reading
Sturdevant's art & science of operative dentistry 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

29. THANK YOU!