Preclinics of Conservative Dental Medicine · MU Sofia

27. Cast metal restorations – indications, contraindications, limitations, cavity preparation.

Covers inlays, onlays and partial veneer crowns made from cast gold, including material choice by gold type, indications, contraindications and limitations. Explains cavity preparation around a single path of draw, with an MO/DO/MOD inlay walkthrough, bevels and flares, and onlay cusp reduction. A summary table compares the three restoration types, and a sectional illustration and a list of common preparation mistakes are included.

Inside: 6 sections · 1 labelled picture · 1 table · 17 flashcards · 7 min

Topic 27 of 53 in the MU Sofia syllabus for Preclinics of Conservative Dental Medicine (Dental Medicine, Year 3). The free AceMed note covers it in 6 sections, about 902 words (7 min of reading), with 17 flashcards.

In this note

  1. Introduction
  2. Types and material
  3. Indications, contraindications and limitations
  4. Cavity preparation
  5. Main mistakes
  6. Key points

Introduction

Cast metal restorations are indirect restorations, usually of gold alloy, cast in the laboratory and cemented at a second visit. This note covers the inlay, the onlay and, briefly, the partial veneer crown: when to use them and how the cavity is prepared. Because a casting is held mainly by friction and cement along one path, its cavity has occlusally divergent walls and bevelled margins – nearly the opposite of an amalgam cavity.

Types and material

Material. The classic material is a high-gold casting alloy, graded by hardness into types I–IV: type II (medium) for inlays, type III (hard) for onlays and partial veneer crowns. Gold is biocompatible, does not tarnish or corrode, wears at about the rate of enamel and is ductile, so a thin margin can be burnished onto the tooth. Other cast alloys (palladium–silver, nickel–chromium, cobalt–chromium) are cheaper but harder and less ductile, so their margins cannot be burnished; nickel can cause allergy.

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