Today, dentures and crowns are some of the most common procedures performed in dental offices, yet their history dates back thousands of years. Dentures are best suited for multiplied missing teeth, whereas crowns are designed for singular teeth. Since the advent of dentures and crowns, the dental field has undergone countless technological advancements to make them what they are today.
History of Dentures
Earliest Dentures
The first recorded denture case dates back to ~2500 BC in Mexico. These dentures were made from animal teeth in Mexico. A few centuries later, in 700 BC, the Etruscans from Italy used gold bands to create one of the earliest pontics, (an artificial tooth used to fill the space created by a missing tooth). Gradually, people in the nearby region shifted to using gold or silver in their dental prosthetics. Historians believed that ancient Egyptians also created some form of dental prosthetic based on archaeological discoveries of skeletons with gold-filled or wood teeth.
Wooden Dentures and Denture Demystification
Around the 16th century during the Edo period, full wood dentures were invented in Japan and utilized until the early 20th century. The Japanese used beeswax, red food coloring, boxwood logs, ivory, and a mugi-urushi bonding mixture of flour and water to create wooden but semi-realistic dentures for patients.
In 1728, the founder of modern dentistry, Pierre Fauchard, created maxillary (upper jaw) and mandibular (lower jaw) dentures, using metal springs to support the two. During the beginning of this century, dentures were typically made of human teeth, animal teeth, or ivory.
While it was true that George Washington had dentures, contrary to popular belief, he did not have wooden ones. Rather, his dentists constructed his dentures out of lead, gold, porcelain, and animal teeth, common denture materials of the time.
Material Modernization
As dentistry progressed, dental specialists began using porcelain, vulcanized (hardened) rubber, and celluloid to construct dentures and replace lost teeth.
Porcelain dentures were invented by Alexis Duchateau and Nicolas Dubois de Chemant in 1776. These dentures gained almost instant popularity due to their aesthetic similarity to natural teeth. However, only Duchateau and Dubois de Chémant succeeded in completing this process with porcelain, as no other individual could prevent the material from shrinking during firing. Consequently, by 1814, porcelain dentures became obsolete.
Vulcanite, or vulcanized rubber, was patented in 1855 by Charles Goodyear. This hardened rubber was used to make dentures, given how cheap yet visually comparable it was compared to gold and ivory and how easily it could be molded to fit the spaces in the mouth.
Celluloid is a nitrate and camphor plastic developed in 1870 by John Wesley Hyatt. Like Vulcanite, celluloid was utilized in dentistry because it could not only imitate luxurious materials, such as ivory and tortoise shells, but also fit well into the mouth.
History of Crowns
Gold Crowns
The earliest dental crowns were made of gold made by the Etruscans from 166 to 201 AD. These crowns had acrylic or porcelain faces in an attempt to camouflage them among the other natural teeth in patients’ mouths, but they were still noticeably different.
Centuries later in 1746, French surgeon and dentist Claude Mouton introduced white enameling to Western European dentistry, suggesting that dentists use white enameling to better camouflage the dentures. In his book Essay d’odontotechnie, ou, dissertation sur les dents artificielles (Essay on odontotechnology, or, a dissertation on artificial teeth), Mouton details the enameling technique, which laid the groundwork for modern dental innovation following his time.
Porcelain Jacket Crowns
In 1903, American Dr. Charles H. Land introduced the porcelain jacket crowns (PJCs). This crown became the first natural tooth-colored, full-coverage restoration. PJCs consist of porcelain clay, heated over platinum foil, and constructed with a cement mixture. Although they were more aesthetically pleasing than the gold crowns, the PJCs were still quite flawed: they were prone to fracturing, the cement used to set them in place would often leak, and the porcelain was not transparent enough to accurately mimic the appearance of natural teeth.
Throughout the 1900s, the original make and design of PJC was optimized: in the 1950s, a metal-porcelain bond—which involves chemical and mechanical attachment of the metal and porcelain crown components—was developed, reducing the likelihood of fracturing upon use, and in the 1960s, PJCs were heated over high temperature-resistant materials called refractory dies rather than platinum foil to strength the crowns In the 1970s, researchers developed collarless ceramometal crowns and porcelain shoulder margins to better conceal the underlying metal the crown is made of. In the 1980s, glass ceramics, such as Dicor and Cerestore, were developed, providing a more aesthetic appearance than previous crowns.
Modern Materials
Today, dentures are typically made from acrylic resin or other plastics. Alternatively, there are dentures made of porcelain, which are more durable but heavier and more expensive than acrylic resin dentures.
Modern crowns are made of a variety of materials. Metal crowns, for example, are made of metals such as gold, palladium, nickel, and chromium. Porcelain-fused-to-metal (PFM) crowns consist of metal covered with porcelain. Pressed ceramic crowns have a ceramic core with multiple outer layers of porcelain. There are also crowns made entirely of ceramic or porcelain, called all-ceramic and all-porcelain crowns. Resin is used for temporary crowns.
Treatment
Ordering and Making Dentures
The first step of the denture-acquisition process is having a dental impression taken, either digitally with a scanner or with putty placed directly in the patient’s mouth. Then, the impressions are sent to a laboratory to create a stone model of the mouth. Here, laboratory technicians use wax registration blocks—horseshoe-shaped blocks of wax–to guide them in placing the artificial teeth before using acrylic or other materials to build the base. Lastly, the laboratory polishes and shines the teeth of the denture set before sending it back to the dentist and fitting it into the patient’s mouth.
Ordering and Making Crowns
To place a crown over a badly-damaged tooth, it must first undergo preparation. Preparing a tooth requires shaving off some of its natural enamel to ensure the crown will properly adhere to it. After the tooth is prepared, impressions of the tooth are taken, which can be done with a scanner or with a putty. Then, the dentist sends the impression to a laboratory to manufacture the crown. While the patient waits for the crown to be made, a temporary resin crown is placed over the affected tooth. Once the crown returns to the dentist from the lab, the temporary crown is taken off, and the patient’s permanent crown is bonded onto their tooth with dental cement.
Crowns were traditionally made only in dental labs, but many dental offices today now have their own crown-making machines, meaning permanent crowns can be milled and placed in-office, usually within the same day as the patient’s first visit.
Crowns are made through milling, casting, or 3D printing. Milling involves carving artificial teeth out of a solid block of zirconia or ceramic based on the patient’s impression. Casting is when material is poured into a mold that mimics the patient’s impression. 3D printing uses resin, metal, and other materials to produce crowns based on the patient’s impression.
Maintenance
To properly maintain crowns and dentures, patients should avoid hard and sticky foods, such as ice and popcorn, as they can dislodge the prosthesis. Also, twice-daily brushing and flossing are necessary to keep the crowns and dentures clean and free of bacterial growth. For dentures, it is suggested to take them out for at least eight hours a day to allow the patient’s natural gums to rest. When properly cared for, crowns can last between five and fifteen years, and dentures can last from seven to ten years.
Conclusion
The evolution of crowns and dentures has drastically transformed, beginning with rudimentary methods using wood and gold and progressing to computer-aided manufacturing. The modern installation processes for each dental prosthesis involve careful preparation and precise crafting to ensure a secure fit in the mouth. To adequately preserve their crowns and dentures, patients should maintain proper hygiene and avoid foods that can damage their prostheses.
