Introduction to Metal-Ceramic Technology

Third Edition

W. Patrick Naylor

• Publisher: Quintessence Publishing Co, Inc
• Year: 2019
• ISBN:
  9780867157536
• Edition: 2
• Topic: Medicine
• Subtopic: Dentistry

For 25 years, the Introduction to Metal-Ceramic Technology has been an essential textbook, and this revised edition underscores its import to the discipline. The author expertly outlines the history and theory behind metal-ceramic restorations and then guides readers through each step of the fabrication process. Although many students do not realize the esthetic possibilities of metal-ceramic technology, this book illustrates how to achieve esthetic results to rival those of all-ceramic materials through treatment planning, clinical procedures, and dental laboratory steps executed at their highest levels. New to this edition are an expanded illustrated glossary, a simplified four-step buttonless technique, fresh analysis of bonding mechanisms, and a full chapter on the esthetic porcelain-margin restoration. Whether you are providing patients with esthetic fixed prosthodontics or are responsible for fabricating lifelike restorations in the dental laboratory, this book can serve as a valuable resource.

1

Chapter

History and Overview

One of the more interesting facets in the annals of dental technology is how the centuries-old artistry of making porcelain evolved into processes that continue to revolutionize modern-day dentistry. The creation of porcelain works of art and fine china were stepping stones in a journey that literally took thousands of years before a few pioneers envisioned potential dental uses for these simple ceramic materials. In fact, it was not until the 19^th century that applications for porcelain in dentistry were created in what would eventually emerge as metal-ceramic technology.

From the late 1800s until today, the pace of change has been extraordinary, thanks in large part to the continued introduction of new products and techniques. You need only examine the origin of dental porcelain to gain an appreciation of just how far ceramic technology has come. At the same time, it is important to recognize the contributions of nations, cultures, and select individuals responsible for the advancements now enjoyed by patients, dental laboratory technicians, and clinicians the world over.

From Earthenware to Stoneware to Porcelain

In his historical account of the development and evolution of dental ceramics, Jones¹ described the role of Chinese artisans in transforming crude fired clay objects into delicate and functional pieces of transparent porcelain. The earliest traces of the origins of ceramics were porous fragments of mud and clay fired at low temperature. These rudimentary products, described as earthenware, were estimated to date back to approximately 23,000 BC.¹ Firing in primitive kilns at temperatures up to 900°C only allowed the clay particles to fuse at points of contact, which yielded a rather porous final result.² And while functional, earthenware items were found to have significant physical limitations. For example, they were not ideally suited for holding and storing liquids because of their porous structure.

Thousands of years later, around 100 BC, the Chinese discovered how to produce more refined ceramic pieces. This next generation of fired objects, referred to as stoneware, was not only stronger than earthenware, but the pieces produced were impervious to water due to improvements in the sintering process.^1,2 Such an advancement in manufacturing was achieved by firing stoneware at temperatures higher than those used to produce earthenware. This significant change to the sintering process resulted in glass formation with sealing of the ceramic surface.²

Anyone who has ever attempted to chronicle the history of ceramics knows that the Chinese also are credited with the subsequent development of porcelain as early as 1000 AD.¹ So refined was this “China stone” or “China ware” that strong, functional, and transparent containers were crafted with walls only a few millimeters thick.¹ Even to this day the terms china and porcelain are used interchangeably when referring to high-quality ceramic items.

Key European Contributors

Despite repeated attempts, European artisans were unsuccessful in their efforts to unravel the secrets of Chinese ceramic technology. In fact, the best that German researchers could do was to produce materials akin to Chinese stoneware. While this outcome was an improvement over porous and crude earthenware, these early European ceramic products reportedly failed to approach the quality, strength, and translucency of fine oriental porcelains.

Father Francis Xavier d’Entrecolles

In what Jones described as “an early example of industrial espionage,” Francis Xavier d’Entrecolles, a Jesuit priest, ingratiated himself with Chinese potters sometime around 1717 in order to learn the porcelain manufacturing process.¹ Father d’Entrecolles lived in what was considered China’s porcelain center, a city named King-te-tching. It was in this industrial region of the Kiangsi Province where he was able not only to obtain Chinese porcelain products but also to acquire essential descriptions of the Chinese manufacturing methods of the day.² With the help of French scientist Réne-Antoine Ferchault de Réaumur, the composition of Chinese porcelain was found to consist of approximately 50% clay (hydrated aluminum silicate, or kaolin), 25% to 30% feldspar (sodium aluminum silicate, or soda, and potassium aluminum silicate, or potash), and 20% to 25% quartz (silica).² Within a few years, Europeans also began producing fine translucent porcelains of their own.³ Yet despite d’Entrecolles’ achievements, ceramics were not immediately recognized as a material of potential value to dentistry in the early 18^th century. But in less than 60 years, that would change.

Alexis Duchâteau and Nicolas Dubois de Chémant

There is evidence in the late 18th century to indicate that an edentulous French apothecary by the name of Alexis Duchâteau was troubled by stained and odiferous dentures with teeth made from Walrus ivory,⁴ a condition probably not uncommon among the general population of that time.¹ Armed with his skills as an apothecary, Duchâteau attempted to make a set of porcelain dentures for himself. Much to his dismay, those initial efforts were less than successful.⁵ It was not until he teamed up with Parisian dentist Nicolas Dubois de Chémant around 1774 that the two were finally able to construct complete dentures from a material they referred to as “mineral paste.”^3–5 Satisfied with the improved fit of his new dentures, Duchâteau returned to his apothecary shop. But Dubois de Chémant became intrigued by his experimentation and went on to reformulate the original mineral paste. He focused his efforts on enhancing the color, increasing the dimensional stability, and improving the attachment of the “mineral teeth” (ie, porcelain teeth) to the denture base.⁶

Dubois de Chémant eventually patented his porcelain formulation and in 1788 published a pamphlet on his work. Yet it was not until 1797 that his more definitive text, A Dissertation on Artificial Teeth, appeared in print. Dubois de Chémant’s “mineral paste dentures” came to be known as “incorruptible teeth” or more simply as “incorruptibles.”^5,7 Dubois de Chémant’s porcelain formulation was said to have enabled denture wearers to have “clean and hygienic dentures,”⁷ but, not everyone hailed Dubois de Chémant’s decision to patent the porcelain paste. It was said that some of his contemporaries regarded his actions as nothing more than the theft of Duchâteau’s original invention.¹

Pierre Fauchard—The father of modern dentistry

As it turns out, the work of Duchâteau and Dubois de Chémant may have been preceded by another French dentist, Pierre Fauchard, who is generally recognized as the father of modern dentistry.¹ Evidently, Fauchard and others reported using what they referred to as “baked enamel” prior to 1760, perhaps as early as the 1720s.¹ Fauchard’s writings described the use of porcelain for the construction of dentures in 1723, but 5 years passed before he actually published his philosophy on dentistry in a 1728 book entitled Le Chirurgien dentiste, ou, Traité des dents (The Surgeon Dentist, or, Treatise on the Teeth).⁵ Then in 1746, some 18 years later, Fauchard released an expanded second edition of his book. His two-volume work was 863 pages in length and contained additional subject matter and improved illustrations. According to Ring,⁵ Fauchard’s writings and philosophy influenced dentistry well into the next century.

Giusseppangelo Fonzi

Another notable advancement occurred around 1806 when Italian dentist Giusseppangelo Fonzi is said to have devised a method to mass produce individual porcelain denture teeth. He also is credited with devising a technique for placing platinum pins in the back of the porcelain teeth, so the pins could be soldered to a metal denture base.^1,3 However, Fonzi did not publicize this achievement until 1808.¹ His individualized porcelain teeth were referred to as “terro-metallic incorruptibles”³ or “terrometallic teeth.”¹

Claudius Ash

In 1837, English goldsmith Claudius Ash is reported to have begun manufacturing fine porcelain denture teeth.⁵ Ash later created an artificial tooth that could be secured over a metal post in either a complete denture or a fixed partial denture. The “tube tooth,” as it was called, went on to enjoy wide popularity in its day.

Arrival of Porcelain in America

Acco...

Table of contents

• Cover
• Title Page
• Dedication
• Copyright Page
• Contents
• In Memoriam
• Preface
• 1 History and Overview
• 2 The Chemistry of Dental Porcelain
• 3 Casting Alloys for Bonding to Dental Porcelain
• 4 The Essentials of Metal-Ceramic Substructure Design
• 5 The Fundamentals of Spruing, Investing, and Casting
• 6 How Does Dental Porcelain Bond to Metal?
• 7 Preparation of the Metal Substructure for Porcelain
• 8 Applying Dental Porcelain to the Metal Substructure
• 9 Adjusting and Finishing the Metal-Ceramic Restoration
• 10 The Porcelain-Margin Restoration
• Glossary
• Appendices