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Direct restorative materials
OBSERVATIONS GORDON J. CHRISTENSEN, D.D.S., M.S.D., Ph.D.
Direct restorative materials What goes where? t is amazing to see the variety of tooth-colored restorative materials on the current market. The days are long gone when only one material could be used most of the time. The variety of tooth-colored restorative materials is impressive.1-3 However, a recent survey on dentists’ use of tooth-colored restorative materials4 has indicated to me that a practical overview of the indications for use of specific materials is in order. It is apparent that in some cases, popular use of toothcolored materials may not be in line with optimum use of the materials when their physical and clinical characteristics are considered. This article lists the most popular tooth-colored restorative materials and discusses the locations of their current clinical use in relation to my suggestions for optimum use. Many of the conclusions expressed in this article are my own, based on
I
clinical experience, the dental literature and reports from dentists who have participated in hundreds of continuing education courses I have presented. ALL-PURPOSE RESIN-BASED COMPOSITE
Most dentists would agree that if they had only one category of direct tooth-colored restorative material from which to choose, they would select the “allpurpose” resin-based composites. These resins have near-optimum strength characteristics, low polymerization shrinkage, only slight expansion and contraction changes, and low wear in service. They are easy to use because of their putty nature, and they provide a highly acceptable range of colors. Dentists trust the all-purpose resin-based composites because some brands have been used successfully for many years. I suggest that when metallic restorations are not being used, all-purpose resin-based composite
materials should be used for most occlusal surface restorations, or for surfaces that are expected to receive routine toothbrush wear. If the described areas are expected to receive extreme wear and metal is not being used, I suggest using highly filled microfilled resin, the most filled brand of which is Heliomolar (Ivoclar Vivadent, Amherst, N.Y.). Use of the popular flowable resins in areas of occlusal contact or expected high wear is questionable because of the reduced wear resistance and lower strength characteristics of this category of materials. Resins containing minute nanofillers are beginning to become popular, but the longterm clinical significance of this very small particle technology is yet to be determined. It would be well to use allpurpose resin-based composites as the standard, routine choice for almost all tooth-colored restorations. JADA, Vol. 134, October 2003
Copyright ©2003 American Dental Association. All rights reserved.
1395
C H R I S T E N S E N
PACKABLE RESIN-BASED COMPOSITES
Packable resin-based composites have not been as popular as some clinicians and manufacturers expected. However, some practitioners find that the stiff putty consistency of these materials provides the ability to produce tighter contact areas on Class II resin-based composite restorations than those afforded by materials with standard viscosity. The most popular resin in this category is Surefil (Dentsply Caulk, York, Pa.). Although the packable characteristic is interesting and sometimes helpful clinically, these resins have only a small part of the market. MICROFILLED RESIN-BASED COMPOSITES
It would be very difficult for me to conduct a high-level, esthetically oriented practice without routine use of microfilled resins. It is well-known that the most desirable characteristics of these resins are their low wear during service and their maintenance of a smooth surface during many years of chewing. The main locations for microfilled resins, either as a total restoration or as a veneer over hybrid resin, are any surfaces that are visible as the patient smiles. This includes the maxillary anterior teeth, some maxillary premolars or any mandibular teeth that are easily observable when the patient smiles or speaks. It is well-known that over time, microfilled resin surfaces become smoother, while hybrid resin surfaces become rougher. In Class II areas in which extreme wear is expected, or as a routine use product for Class II areas, the highly filled microfilled product Heliomolar is indi1396
cated because of its low wear characteristics. FLOWABLE RESIN-BASED COMPOSITES
The ease of use of flowable resin-based composites explains their popularity, but I question the logic of practitioners when they use this category of material in locations with high wear potential or great need of strength. Generally, flowable resin-based composites contain less filler than do all-purpose resins. Thus, their strength and wear resistance is compromised in comparison with those of allpurpose materials. Does it make sense to use flowables in areas of expected high wear? Unless the patient is aged and has only a few years to live, the service potential of flowable resin makes it a less acceptable choice than all-purpose resin or microfilled resin. The major areas of use for flowable composite should be limited to situations in which minimal wear is expected. An appropriate use is for filling small pits and fissures (in other words, in preventive resin restorations). Even in those situations, I prefer to place fully filled resin, preceded by a slight amount of flowable resin to wet the acid-etched enamel surfaces. The heavier viscosity, allpurpose resin forces the small amount of uncured flowable resin out of the tooth preparation before the restoration is polymerized. Small defects that need a minimal amount of restorative material also are acceptable locations in which to use flowable resin. An example is filling a small crack or pit in a tooth. Many dentists report that they are using flowable resin-
based composites to create bases or liners under restorations. One of their reasons for this use is understandable, since the flowable resin is easy to adapt to the undercuts and irregularities of cavity preparations. However, flowable resins do not fulfill the traditional purpose of liners and bases: pulp protection. The single most logical reason for using flowable resin as a base or liner appears to be ease of use, but flowable resins are just diluted conventional resins, and they contain the same potentially pulp-irritating materials that conventional resins do. Instead of flowable resin, why not use a base or liner material that also bonds to tooth structure and releases fluoride, such as resin-modified glass ionomer? Other materials to be discussed below appear to be more appropriate. In my opinion, the high acceptance of flowable resinbased composite materials by the profession indicates too much optimism about their service potential. RESIN-MODIFIED GLASS IONOMER
The two most popular resinmodified glass ionomers, GC Fuji II LC (GC America, Alsip, Ill.) and Vitremer Core buildup/Restorative (3M ESPE, St. Paul, Minn.), are underused, in my opinion. Although these materials do not have the esthetic acceptability of other materials discussed here so far, they have a natural bond to tooth structure, and they release fluoride during service. These characteristics make them nearly ideal for repair of crown margins and for restoration of Class V areas in highly cariesprone mouths. When liners or bases are
JADA, Vol. 134, October 2003 Copyright ©2003 American Dental Association. All rights reserved.
C H R I S T E N S E N
needed in tooth preparations intended for resin-based composite, resin-modified glass ionomer is the ideal material. Popular liner materials are Vitrebond (3M ESPE) and GC Fuji Lining LC (GC America). Clinicians report that either of these materials used on the deepest portion of tooth preparations has reduced or eliminated postoperative tooth sensitivity. Conventional glass ionomer, without resin added, has minimal use in North America, where highly esthetic restorative materials have been preferred. Technique sensitivity and esthetic limitations are the major reasons for the minimal use, in spite of fluoride release and significant caries-preventive characteristics. COMPOMER RESTORATIVE MATERIAL
Compomer had immediate acceptance when it was introduced a few years ago. Dentists liked its ease of use and relatively good initial esthetic result. However, its possibilities in terms of fluoride release did not measure up to expectations, and the materials needed a bonding agent to have adequate
retention and seal. As a result, today, use of compomer is less than might have been expected. My own personal preference for use of compomers is as fillers in “potholes” in tooth preparations for crowns or fixed prostheses. When previously placed restorations are removed during crown preparations, small holes and undercuts remain in tooth structure. These defects have the possibility of interfering with adequate removal of impression material, and the provisional restorations may become locked on the tooth preparations when the provisional restorations polymerize during construction. The clinician can place compomer in these holes easily by applying a small amount of self-etching primer in the hole, placing the compomer and curing it. Final tooth preparation can begin immediately. Another use for compomers that is well-accepted around the world is as a posterior tooth restorative for pediatric teeth. SUMMARY
The many tooth-colored restorative materials available today present a confusing array of
products. However, they are the best group of tooth-colored restorative materials availDr. Christensen is able in dentistry co-founder and senior to date. Dentists consultant of Clinical Research Associates, are advised to 3707 N. Canyon Road, Suite No. 3D, Provo, learn the charUtah 84604. He has a acteristics of master’s degree in dentistry each category of restorative and a doctorate in edutooth-colored cation and psychology. is board-certified materials and to He in prosthodontics. base their judg- Address reprint requests to ment of which Dr. Christensen. type to use on an in-depth consideration of the many products available. ■ The views expressed are those of the author and do not necessarily reflect the opinions or official policies of the American Dental Association. Educational information on topics discussed by Dr. Christensen in this article is available through Practical Clinical Courses and can be obtained by calling 1-800-223-6569. 1. Christensen GJ. Resin restorations for anterior teeth: 1995. JADA 1995;126:1427-8. 2. Christensen GJ. Restorative dentistry for pediatric teeth: state of the art 2001. JADA 2001;132:379-81. 3. Christensen GJ. The need for cariespreventive restorative materials. JADA 2000;131:1347-9. 4. Kehoe B. Direct restoratives, part I. Dent Prod Rep July 2003:20-6.
JADA, Vol. 134, October 2003 Copyright ©2003 American Dental Association. All rights reserved.
1397
Direct restorative materials What goes where? t is amazing to see the variety of tooth-colored restorative materials on the current market. The days are long gone when only one material could be used most of the time. The variety of tooth-colored restorative materials is impressive.1-3 However, a recent survey on dentists’ use of tooth-colored restorative materials4 has indicated to me that a practical overview of the indications for use of specific materials is in order. It is apparent that in some cases, popular use of toothcolored materials may not be in line with optimum use of the materials when their physical and clinical characteristics are considered. This article lists the most popular tooth-colored restorative materials and discusses the locations of their current clinical use in relation to my suggestions for optimum use. Many of the conclusions expressed in this article are my own, based on
I
clinical experience, the dental literature and reports from dentists who have participated in hundreds of continuing education courses I have presented. ALL-PURPOSE RESIN-BASED COMPOSITE
Most dentists would agree that if they had only one category of direct tooth-colored restorative material from which to choose, they would select the “allpurpose” resin-based composites. These resins have near-optimum strength characteristics, low polymerization shrinkage, only slight expansion and contraction changes, and low wear in service. They are easy to use because of their putty nature, and they provide a highly acceptable range of colors. Dentists trust the all-purpose resin-based composites because some brands have been used successfully for many years. I suggest that when metallic restorations are not being used, all-purpose resin-based composite
materials should be used for most occlusal surface restorations, or for surfaces that are expected to receive routine toothbrush wear. If the described areas are expected to receive extreme wear and metal is not being used, I suggest using highly filled microfilled resin, the most filled brand of which is Heliomolar (Ivoclar Vivadent, Amherst, N.Y.). Use of the popular flowable resins in areas of occlusal contact or expected high wear is questionable because of the reduced wear resistance and lower strength characteristics of this category of materials. Resins containing minute nanofillers are beginning to become popular, but the longterm clinical significance of this very small particle technology is yet to be determined. It would be well to use allpurpose resin-based composites as the standard, routine choice for almost all tooth-colored restorations. JADA, Vol. 134, October 2003
Copyright ©2003 American Dental Association. All rights reserved.
1395
C H R I S T E N S E N
PACKABLE RESIN-BASED COMPOSITES
Packable resin-based composites have not been as popular as some clinicians and manufacturers expected. However, some practitioners find that the stiff putty consistency of these materials provides the ability to produce tighter contact areas on Class II resin-based composite restorations than those afforded by materials with standard viscosity. The most popular resin in this category is Surefil (Dentsply Caulk, York, Pa.). Although the packable characteristic is interesting and sometimes helpful clinically, these resins have only a small part of the market. MICROFILLED RESIN-BASED COMPOSITES
It would be very difficult for me to conduct a high-level, esthetically oriented practice without routine use of microfilled resins. It is well-known that the most desirable characteristics of these resins are their low wear during service and their maintenance of a smooth surface during many years of chewing. The main locations for microfilled resins, either as a total restoration or as a veneer over hybrid resin, are any surfaces that are visible as the patient smiles. This includes the maxillary anterior teeth, some maxillary premolars or any mandibular teeth that are easily observable when the patient smiles or speaks. It is well-known that over time, microfilled resin surfaces become smoother, while hybrid resin surfaces become rougher. In Class II areas in which extreme wear is expected, or as a routine use product for Class II areas, the highly filled microfilled product Heliomolar is indi1396
cated because of its low wear characteristics. FLOWABLE RESIN-BASED COMPOSITES
The ease of use of flowable resin-based composites explains their popularity, but I question the logic of practitioners when they use this category of material in locations with high wear potential or great need of strength. Generally, flowable resin-based composites contain less filler than do all-purpose resins. Thus, their strength and wear resistance is compromised in comparison with those of allpurpose materials. Does it make sense to use flowables in areas of expected high wear? Unless the patient is aged and has only a few years to live, the service potential of flowable resin makes it a less acceptable choice than all-purpose resin or microfilled resin. The major areas of use for flowable composite should be limited to situations in which minimal wear is expected. An appropriate use is for filling small pits and fissures (in other words, in preventive resin restorations). Even in those situations, I prefer to place fully filled resin, preceded by a slight amount of flowable resin to wet the acid-etched enamel surfaces. The heavier viscosity, allpurpose resin forces the small amount of uncured flowable resin out of the tooth preparation before the restoration is polymerized. Small defects that need a minimal amount of restorative material also are acceptable locations in which to use flowable resin. An example is filling a small crack or pit in a tooth. Many dentists report that they are using flowable resin-
based composites to create bases or liners under restorations. One of their reasons for this use is understandable, since the flowable resin is easy to adapt to the undercuts and irregularities of cavity preparations. However, flowable resins do not fulfill the traditional purpose of liners and bases: pulp protection. The single most logical reason for using flowable resin as a base or liner appears to be ease of use, but flowable resins are just diluted conventional resins, and they contain the same potentially pulp-irritating materials that conventional resins do. Instead of flowable resin, why not use a base or liner material that also bonds to tooth structure and releases fluoride, such as resin-modified glass ionomer? Other materials to be discussed below appear to be more appropriate. In my opinion, the high acceptance of flowable resinbased composite materials by the profession indicates too much optimism about their service potential. RESIN-MODIFIED GLASS IONOMER
The two most popular resinmodified glass ionomers, GC Fuji II LC (GC America, Alsip, Ill.) and Vitremer Core buildup/Restorative (3M ESPE, St. Paul, Minn.), are underused, in my opinion. Although these materials do not have the esthetic acceptability of other materials discussed here so far, they have a natural bond to tooth structure, and they release fluoride during service. These characteristics make them nearly ideal for repair of crown margins and for restoration of Class V areas in highly cariesprone mouths. When liners or bases are
JADA, Vol. 134, October 2003 Copyright ©2003 American Dental Association. All rights reserved.
C H R I S T E N S E N
needed in tooth preparations intended for resin-based composite, resin-modified glass ionomer is the ideal material. Popular liner materials are Vitrebond (3M ESPE) and GC Fuji Lining LC (GC America). Clinicians report that either of these materials used on the deepest portion of tooth preparations has reduced or eliminated postoperative tooth sensitivity. Conventional glass ionomer, without resin added, has minimal use in North America, where highly esthetic restorative materials have been preferred. Technique sensitivity and esthetic limitations are the major reasons for the minimal use, in spite of fluoride release and significant caries-preventive characteristics. COMPOMER RESTORATIVE MATERIAL
Compomer had immediate acceptance when it was introduced a few years ago. Dentists liked its ease of use and relatively good initial esthetic result. However, its possibilities in terms of fluoride release did not measure up to expectations, and the materials needed a bonding agent to have adequate
retention and seal. As a result, today, use of compomer is less than might have been expected. My own personal preference for use of compomers is as fillers in “potholes” in tooth preparations for crowns or fixed prostheses. When previously placed restorations are removed during crown preparations, small holes and undercuts remain in tooth structure. These defects have the possibility of interfering with adequate removal of impression material, and the provisional restorations may become locked on the tooth preparations when the provisional restorations polymerize during construction. The clinician can place compomer in these holes easily by applying a small amount of self-etching primer in the hole, placing the compomer and curing it. Final tooth preparation can begin immediately. Another use for compomers that is well-accepted around the world is as a posterior tooth restorative for pediatric teeth. SUMMARY
The many tooth-colored restorative materials available today present a confusing array of
products. However, they are the best group of tooth-colored restorative materials availDr. Christensen is able in dentistry co-founder and senior to date. Dentists consultant of Clinical Research Associates, are advised to 3707 N. Canyon Road, Suite No. 3D, Provo, learn the charUtah 84604. He has a acteristics of master’s degree in dentistry each category of restorative and a doctorate in edutooth-colored cation and psychology. is board-certified materials and to He in prosthodontics. base their judg- Address reprint requests to ment of which Dr. Christensen. type to use on an in-depth consideration of the many products available. ■ The views expressed are those of the author and do not necessarily reflect the opinions or official policies of the American Dental Association. Educational information on topics discussed by Dr. Christensen in this article is available through Practical Clinical Courses and can be obtained by calling 1-800-223-6569. 1. Christensen GJ. Resin restorations for anterior teeth: 1995. JADA 1995;126:1427-8. 2. Christensen GJ. Restorative dentistry for pediatric teeth: state of the art 2001. JADA 2001;132:379-81. 3. Christensen GJ. The need for cariespreventive restorative materials. JADA 2000;131:1347-9. 4. Kehoe B. Direct restoratives, part I. Dent Prod Rep July 2003:20-6.
JADA, Vol. 134, October 2003 Copyright ©2003 American Dental Association. All rights reserved.
1397