CHAPTER OUTLINE
- • Historical Background
- • Ideal Requirements for Dental Materials
- • Classification
- • Evaluation of Dental Materials
- • International Organization for Standardization (ISO), Subcommittees and Working Groups
- • Development Process of ISO Standards
- • Other Dental Standard Organizations
- • Safety of Restorative Materials
‘The way to get started is to quit talking and start doing’.
—Walt Disney
INTRODUCTION
Throughout the history of human civilization, replacement of lost body parts has challenged mankind and replacement of tooth and adjacent structures is no exception. Dental practitioners have always sought for an ideal material which will replace the lost tooth and adjacent tissues thus, restoring esthetics and function. The quest for an ideal material will continue to be focused by the clinicians worldwide. The practice of dentistry is largely dependent on material, its manipulation and techniques of use. Material science will keep on evolving with newer innovations and techniques and dental practitioners will have to keep updated with latest information which would be highly valuable for treating the patient more efficiently and effectively.
DEFINITION
The science of dental material is dealing with the development, properties, manipulation, care, evolution, and evaluation of materials used in the treatment and prevention of dental diseases.
Dental materials can be broadly categorized as metals, ceramics, composites and polymers.
Metals in pure form are rarely used in dentistry except pure titanium and gold foils. Pure titanium finds application in fabrication of dental implants, inlays, onlays, crowns and fixed dental prosthesis. Pure gold in form of gold foils is used as directly filling material, which is rare currently.
Dental ceramic is widely used to fabricate inlays, onlays, crowns and fixed dental prosthesis. Metal ceramic and all ceramic restorations are commonly used because of improved strength and higher esthetics. Yttria Stabilized Zirconia (YSZ) can also be used for endodontic post and core and manufacturing implant body.
Dental composites, cements and polymers are commonly used as preventive as well as restorative material. Some of these materials are capable of releasing sustained and controlled agents capable of preventing dental disease such as dental caries.
However, despite massive strides in technology in dentistry still there is a search for ideal restorative material.
HISTORICAL BACKGROUND
Timeline for history of dental materials is as follows:
- 4500–4000 BC: Babylonians, Assyrians and Egyptians were familiar with silver, gold, copper and lead
- 990 BC: Iron was used by Phoenicians
- 700–500 BC: Gold crowns and bridges were commonly used by Etruscans
- About 100 AD: Celsus advocated the use of lint and lead for filling large cavities
- 1480: Johannes Arculanus used gold leaf to fill cavities to restore teeth
- 1460–1520: Giovanni de Vigo described the removal of caries before using gold leaf for filling the cavities
- 1562: Ambroise Pare prepared artificial teeth from bone and ivory (Fig. 1.1)
- 1728: Pierre Fauchard called Father of Modern Dentistry (Fig. 1.2), described materials and practices in dentistry in his book Le chirurgien dentiste, ou Traite des dents
- 1746: Claude Mouton introduced the gold shell crowns which were swaged from one piece of metal
- 1756: Philip Pfaff first used plaster models prepared from sectional wax impressions
- 1789: Dr John Greenwood made dentures for US President George Washington (Fig. 1.3)
- 1801: First American book on dentistry published by RC Skinner titled as ‘Treatise on the Human teeth’
- 1812: Gold foil produced by Marcus Bull
- 1832: James Snell introduced the zinc oxychloride cement
- 1833: Silver paste which was amalgam of silver and mercury was introduced in the United States by Crawcour brothers
- 1838: Ash tube tooth was first marketed (Fig. 1.4)
- 1840: First dental school called the Baltimore College of Dental Surgery established in the United States
- 1864: Rubber dam introduced to isolate teeth by Barnum
- 1870: Zinc phosphate cement was first used
- 1878: Richmond Crown was introduced
- 1878: Silicate cement developed by Fletcher
- 1885: Davis Crown was introduced
- 1889: Charles Land introduced porcelain jacket crowns and high fusing inlays
- 1907: WH Taggart introduced Lost wax technique for casting
- 1930: Unfilled resins as PMMA (poly methyl methacrylate) were first used as denture base resins
- 1938: First nylon toothbrush introduced with synthetic bristles
- 1942: Diamond abrasive instruments introduced for dental use
- 1949: Oskar Hagger first bonded acrylic resin with the tooth dentin
- 1951: Inorganic fillers were added to the direct filling materials
- 1955: Michael Buonocore first introduced the acid etch technique for bonding to tooth enamel
Fig. 1.3: Dentures for American President George Washington made with ivory, wood and metal fasteners.
- 1956: RL Bowen developed the first generation dentin adhesive
- 1962: Bowen developed Bis-GMA which was used as composite resins for restorations
- 1965: PI Branemark first placed dental implant in human jaw
- 1968: Smith introduced the zinc polycarboxylate cement
- 1971: Dr Francois Duret (France)—First developed dental CAD-CAM system
- 1972: Glass ionomer cement was introduced by A Wilson and Kent
- 1977: Light cure composites first introduced in the market
- 1980s: Introduction of lasers in dentistry
- 1985: Dr Werner Mormann and Dr Marco Brandestini (Switzerland)—developed the first commercial CAD-CAM system (CEREC)
- 1996: Chemical vapor deposition (CVD) burs were introduced for efficient cutting
- 1997: Swift–Ferrari–Goracci introduced the self-etching adhesives
- 1997: Erbium YAG laser was first used on dentin to treat tooth decay
- 2007: Seventh generation bonding agents were introduced
- 2009: CEREC AC powered by BlueCam was introduced to make impressions and create crowns or veneers chairside.
IDEAL REQUIREMENTS FOR DENTAL MATERIALS
Although currently no single dental material meets all the ideal requirements.
The requirements for an ideal dental material is given below:
- Should be biocompatible, nonirritating, nontoxic and inert
- Should have adequate strength to resist masticatory load
- Should be tarnish and corrosion resistant
- Should be dimensionally stable
- Should be esthetic
- Should be easy to manipulate and should be easily available
- Should be odorless and tasteless
- Should have good bonding to the tooth and other restorative materials
- Should be easily repairable
- Should be economical.
EVALUATION OF DENTAL MATERIALS
In 1919, the US Army approached the National Bureau of Standards to set up specifications for the evaluation and selection of dental amalgam to be used for Federal services. The research was carried out under the leadership of Wilmer Souder and was published in 1920. Later in the year 1928, American Dental Association (ADA) was established. ADA laid down specifications for each dental material to be used clinically. In this year ADA took over the dental research section at the National Bureau of Standards.
ADA Acceptance Program
ADA developed the ADA acceptance program (Fig. 1.5) to identify the physical and chemical properties of the material that ensures satisfactory performance of the material when properly manipulated.
The products launched by the manufacturer are tested to comply with the required specifications. If the material clears the required specification it is given seal of acceptance. This can be provisional or complete acceptance depending on the extensiveness of the clinical and laboratory results. In the year 1993, ADA published the report Clinical Products in Dentistry—A Desktop Reference which listed all the accepted, certified dental materials, instruments, equipment and therapeutics. This served as quick reference guide to update dentists about new products and helped in selection of various materials.
In 1976, Medical Devices Amendments were signed into the law to protect the human population from hazardous and ineffective devices used in medical or dental field.
A dental device classification panel developed to classify devices used in dentistry based on the relative risk, is as follows:
All dental products or devices should adhere to appropriate specification or standards. The manufacturer is responsible to comply with these specifications solely. It is important for a product to display the following information:
- Serial number
- Composition
- Physical properties as obtained after standard test
- Biocompatibility data if needed
- Information about every provision of official specification about that product.
International Standards
With the increase in demand for dental devices around the world, the tests for safety and effectiveness should confirm to the international standards. There are two organizations namely FDI (Fédération Dentaire Internationale) and the ISO (International Organization for Standardization) which work toward establishing international specification for dental materials. Initially, FDI formulated international specifications for dental materials and later ISO which is a nongovernment international organization developed international standards.
The specifications are highly beneficial for dentist worldwide to select materials based on criteria which are impartial and reliable. On request from the FDI, the ISO organization established a technical committee (TC) for dentistry called as TC 106. This committee is involved in standardizing and testing methods to develop specifications for dental materials, equipments, appliances and instruments.
ISO technical committee—TC 106 Dentistry was established based on the FDI specification and ISO standards. Later subcommittees were formed to cover all 7the dental products. For example, TC 106/SC 1 restorative and filling materials.
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO), SUBCOMMITTEES AND WORKING GROUPS
In 2011, TC 106 Dentistry formed 7 subcommittees and 58 working groups to develop specifications for testing the safety and efficacy of dental products. Out of the 7 committees, 3 are involved and cover most of the dental restorative materials listed by the ISO standard program under the guidance of TC 106.
The three subcommittees are given below:
- TC 106/SC 1: Filling and Restorative MaterialsUnder this category, 10 working groups (WG) are included:
- TC 106/SC 1/WG 1: Zinc oxide eugenol cements and non-eugenol cements
- TC 106/SC 1/WG 2: Endodontic materials
- TC 106/SC 1/WG 5: Pit and fissure sealants
- TC 106/SC 1/ WG 7: Amalgam or mercury
- TC 106/SC 1/WG 9: Resin-based filling materials
- TC 106/SC 1/WG 10: Dental luting cements, bases and liners
- TC 106/SC 1/WG 11: Adhesion test methods
- TC 106/SC 1/WG 13: Orthodontic products
- TC 106/SC 1/WG 14: Orthodontic elastics
- TC 106/SC 1/WG 15: Adhesive components.
- TC 106/SC 2: Prosthodontics MaterialsUnder this category, 16 WG are included:
- TC 106/SC 2/WG 1: Dental ceramics
- TC 106/SC 2/WG 2: Dental base alloys
- TC 106/SC 2/WG 6: Color stability test methods
- TC 106/SC 2/WG 7: Impression materials
- TC 106/SC 2/WG 8: Noble metal casting alloys
- TC 106/SC 2/WG 10: Resilient lining materials
- TC 106/SC 2/WG 11: Denture base polymers
- TC 106/SC 2/WG 12: Corrosion test methods
- TC 106/SC 2/WG 13: Investments
- TC 106/SC 2/WG 14: Dental brazing materials
- TC 106/SC 2/WG 16: Polymer veneering and die materials
- TC 106/SC 2/WG 18: Dental waxes and baseplate waxes
- TC 106/SC 2/WG 19: Wear test methods
- TC 106/SC 2/WG 20: Artificial teeth
- TC 106/SC 2/WG 21: Metallic materials
- TC 106/SC 2/WG 22: Magnetic attachments.
- TC 106/SC 8: Dental ImplantsUnder this category, 5 WG are included:
- TC 106/SC 8/WG 1: Implantable materials
- TC 106/SC 8/WG 2: Preclinical biological evaluation and testing
- TC 106/SC 8/WG 3: Content of technical files
- TC 106/SC 8/WG 4: Mechanical testing
- TC 106/SC 8/WG 5: Dental implants—terminology.
DEVELOPMENT PROCESS OF ISO STANDARDS
In the first phase, the working group of a particular product are involved and the technical experts of interested countries. An agreement is established between them and then in the second phase, the countries involved determine the detailed specifications within the standard. The last and final phase involves drafting of the final approval called Draft International Standard (DIS) by at least 75% of all voting members. After this, it is published in the ISO International Standard.
Most of these standards require periodic revision due to technological advancement, new materials and methods and safety requirements. All ISO standards require revision at the interval of not more than 5 years. Some of these standards may require revision earlier than that.
OTHER DENTAL STANDARD ORGANIZATIONS
Other dental standard organizations are:
- Australian Dental Standards laboratory: Established in 1936
- NIOM (Nordiska Institutet for Odontologisk Material provning): It was established for Scandinavian countries (Denmark, Finland, Iceland, Norway and Sweden) in 1969, for testing, certifying and research regarding dental materials and equipments. This institute became functional in 1973
- CEN (Comite Europeen de Normalisation): It established the Task Group 55 to develop European standards. CE denotes the mark of conformity with the Essential Requirements in the Medical Device Directive. CEN describes dental materials, implants and equipment in Europe as ‘medical devices used in dentistry’. All the medical devices used in dentistry marketed in Europe should have the seal of CE mark of conformity.
The field of research in dentistry is expanding in areas of metallurgy, material science, mechanical engineering, engineering mechanics, ceramics and polymer science.8
These fields suggest interdisciplinary approach when examining a material. Ultimate test of material is the function and longevity in the patient's mouth. Also, clinical reviews of specifications of various dental materials become more essential with the increased focus on “evidence-based dentistry”.
SAFETY OF RESTORATIVE MATERIALS
There is no dental material which can be considered absolutely safe. The term safety is relatively based on the assumption that advantage of using a material far outweighs the drawbacks of using it. The two main biological effects are allergic and toxic reactions.
A Swiss based alchemist named Paracelsus (1493–1541 AD) formulated a principle on which the current field of toxicology exists. He stated that, All substances are, poisons; there is none which is not a poison. The right dose differentiates a poison from a remedy.
A component in a dental material is capable of producing an allergic reaction in an individual. A chemical agent can induce an antigen–antibody reaction and patient can show signs and symptoms of allergy. Although allergy and side effects in dental treatment is extremely low which is reported as 0.14% in the general population.
CONCLUSION
There has been marked increase in newer materials, equipment and techniques in dentistry. A professional is expected to have an update on these materials because of the change in demands of modern dental practice. There will be greater restorative needs in future because of more emphasis on preventive treatment. Research in dental materials is no longer confined to only material science but has an interdisciplinary approach also because of interaction of materials at cellular and molecular levels. Also studies on tissue regeneration will continue and can, in future, totally change the concept of current use of materials.
TEST YOURSELF
Essay Questions
- Classify dental materials? Write the ideal requirements of dental materials? Add a note on evaluation of dental materials?
- Describe various international standards for evaluating safety of dental materials?
Short Notes
- ADA acceptance program.
- Auxillary materials.
1. An ideal restorative material should be all, except
- Compatible with natural tissues
- Should match adjacent tooth structure
- Should bond mechanically to the tooth
- Should initiate repair of tissues
2. Auxillary dental materials:
- Helps in preventing caries
- Helps in restoring decayed tooth
- Facilitate in fabrication of dental prosthesis
- Helps in repairing damaged tooth
1. C | 2. C |
BIBLIOGRAPHY
- American Dental Association: Clinical Products in Dentistry: A Desktop Reference. Chicago; 1983.
- American Dental Association: Dentist's Desk Reference: Materials, Instruments and Equipment, 2nd edition. Chicago; 1983.
- American Dental Association: Guide to Dental Materials and Devices, 8th edition. Chicago; 1976.
- Anusavice KJ. Phillip's Science of Dental Materials, 11th edition. Saunders St. Louis; 2003.
- Craig RG, Powers JM. Restorative Dental Materials, 11th edition. St. Louis, Mosby; 2001.
- Lufkin AW. A History of Dentistry, 3rd edition. Philadelphia, Lea and Febiger; 1948.
- O’ Brien, William J. Dental Materials and Their Selection, 2nd edition. Chicago, Quintessence; 1997.
- Ring ME. John Greenwood, Dentist to President Washington. J Calif Dent Assoc. 2010;38(12):846-51.
- Weinberger BW. An Introduction to the History of Dentistry in America: Volume Two, 1st edition. St. Louis, Mosby, 1948. p. 408.