Introduction
The focus of this paper is to examine the diagnosis and treatment of moderate to severe dental caries using resin composite materials, concentrating on lesions in posterior teeth. In order to gain a comprehensive understanding of the subject, the paper details the diagnosis and treatment parameters of such lesions, the choice of specific composite restorative materials, and placement technique. Furthermore, a comparison is made between resin-based composites and amalgam, and the predicted outcomes of composite restorations under various circumstances are discussed.

Problem
The first and most crucial step in caries treatment is the diagnosis. Visual, tactile, and radiographic methods have all been used as methods of determining the extent of caries penetration into tooth structure. Depth classification of carious lesions not only influences what type of treatment is indicated but also affects the outcome of the restorative procedure. The iceberg metaphor for conceptualizing dental caries defines carious lesions as follows (Pitts, 2001):

The current trend in restorative dentistry shows an increasing use of resin composite for the treatment of moderate to severe carious lesions in posterior teeth, specifically for the previously defined D3 lesions. According to a Finnish study published in 2001, 87% of general practitioners restore Class I lesions with composites as opposed to 10% that select amalgam. For Class II lesions, 40% of dentists prefer composite restorations while only 10% opt for amalgam (Heinikainen, et al., 2001). In light of this recent trend, it is essential that all dentists become educated on the benefits and limitations of the various types of composites so that they are able to make the best restorative material choice.

Intervention
Material Selection - Composite Resins:
Over the last 25 years, the development of composite resins as an esthetic option to amalgam, and other metallic restorative materials, has been apparent in the dental community. Restorative materials that mimic the appearance of natural tooth structure are in high demand by those seeking dental care today. From the dental professional's side of the issue, the need for an esthetic yet durable restorative material has increased as well. These two forces, the public's wants and the professional's need to satisfy those wants, have led to much research and development by manufacturers to provide the ideal product. Consequently, there are many types and brands of composite resins available for dentists to choose from.

First, the different types of resin composite material available need to be considered (Combe et al., 1999).

Composite resins placed in moderate carious lesions have gone from lack of acceptance to a common and routine procedure in the last 20 years. One of the reasons for the movement from lack of acceptance to a routine procedure is the fact that during the last decade, the average filler size was drastically reduced. Consequently, the smaller distribution of the submicrometer-sized-particle fillers currently used has optimized the filler load and improved the mechanical and wear characteristics (Turkun et al., 2001). To illustrate this point, consider this seventeen-year clinical study of UV-cured resin composite restorations that looks at composites placed in 1977. These composites had average particle sizes as follows: 7.2 _m for Estilux(Kulzer), 12-15 _m for Nuva-Fil(Caulk), and 15 _m for Uvio-Fil(ESPE), and particle size distributions of 1-20 _m for Estilux, 2-30 _m for Nuva-Fil, and 1-30 _m fro Uvio-Fil (Wilder et al., 1999). One of the most recent composites to come on the market and into the University of Minnesota Dental School is Filtek Z250(3M ESPE). It has an average particle size of 0.6 _m and a particle size distribution of less than 0.8 _m. Z250 is composed of bis-GMA, UDMA and bis-EMA(6) resins, contains a zirconia silica filler, and can be used with any UV-cured resin adhesive (CRA, 2002). As a result, Z250 demonstrates greatly improved physical characteristics over to the older composites.

A recent CRA report from September 2002 studied the one-year clinical durability of Heliomolar(Ivoclar), Herculite XRV(Kerr), Prisma TPH(Dentsply) and 3M ESPE's Z100 and Filtek Z250, the current choice of the University of Minnesota School of Dentistry. This paper will focus on the properties of these five composite resins commonly used for treatment of moderate carious lesions. Each of these brands of composite is of the hybrid type except for Heliomolar, which is a microfilled composite. The price per milliliter ranges from $27-37. This study used the modified Ryge criteria for evaluating the physical and mechanical properties of composites. This method looks at: color match, cavosurface margin discoloration, marginal adaptation, secondary caries, surface texture, and anatomical form or wear (Turkun et al., 2001). Here is a summary of the findings of the CRA report from September 2002:

The rate of wear that is normal for enamel on enamel is reportedly 22-29 _m per year. Heliomolar and Filtek Z250 were closest to this value at 34 _m and 38 _m per year respectively. Indistinguishable margins are ideal. Heliomolar had 30% "Excellent" margins but more than 50% with less than "Very Good" margins, while Filtek Z250 had 77% with "Very Good," according to the scale provided in the report. Heliomolar, Filtek Z250 and Herculite XRV had the best smoothness. Evaluation of color matching shows Z250 and Herculite XRV were both graded "Excellent", margin discoloration was graded "Excellent" for all 5 brands. No secondary caries were detected in this one-year study, and polymerization shrinkage was only 1.8% by volume for Filtek Z250 and 2.2% for Heliomolar. Overall, Heliomolar and Filtek Z250 were statistically similar and both were superior to the other tested brands.

The demand for an esthetic and durable restorative material by the public and dentists has pushed manufacturers to come up with a much more durable line of resin composites in comparison to those used in the 70's. It appears that the new composite resins are closer than ever to the ideal durable esthetic restorative material.

Material Selection - One-Bottle Adhesives:
Deep carious lesions often require the use of a dentin bonding agent in order to provide the patient with an optimum restoration. Many practitioners and institutions, such as the University of Minnesota School of Dentistry, utilize "one-bottle" adhesive systems. These systems were designed to decrease steps in the bonding process, and essentially reduce chair time for the practitioner. Besides reducing the time involved, it is possible that the fewer steps may reduce the risk of contamination of the system as Taskonak and Sertgoz (2002) suggest in their study Shear Bond Strengths of Saliva Contaminated ŒOne-bottle' Adhesives. In the study Taskonak and Sertgoz conducted, however, it was shown that "contamination of dentin [by saliva] has no adverse effect on the bonding efficiency of one-bottle adhesive systems". Saliva was introduced during the bonding process after etching with phosphoric acid for one study group, and after light curing the adhesive for another group. A control group did not receive any contamination during the bonding procedures. It was concluded from the data that there were no statistical differences between all three groups in the study. Thus the utilization of one-bottle systems may not only reduce chair time in theory, but may also allow for adequate bonding in an inadequate isolation situation.

A carious lesion that is deep into dentin often comes into close proximity of the pulp chamber and/or horns of the tooth. To avoid the possibility of a pulp exposure, a practitioner may choose to leave some carious dentin in the preparation. Studies conducted by Yoshiyama et al. (2002) and Kwong et al. (2002) have investigated the bonding strengths of one-bottle systems to carious dentin. Both studies found lower microtensile bond strengths of one-bottle systems when compared to bond strengths of adhesives applied to sound dentin. It is hypothesized that the lower bond strengths may be attributed to: 1) the inability to properly etch through a hypermineralized layer found on sclerotic dentin, 2) the lack of resin tag formation due to sclerotic casts that occlude the dentin tubules, and 3) bacteria within the resin layer may create defects that reduce the strength of the resin (Kwong et al., 2002). Yoshiyama et al. (2002) suggest that bonding to carious dentin may not be a problem, however, if there is sound dentin/enamel surrounding the area to afford high bonding strength to the adhesive resin. At the same time, Yoshiyama et al. also advise practitioners to remove as much sclerotic dentin as possible prior to placement of the adhesive and resin composite.

Instead of leaving carious dentin in a preparation, a clinician may also choose to remove all of the sclerotic dentin and in the process create a pulp exposure. In this circumstance, a practitioner will often perform direct pulp capping with calcium hydroxide. Calcium hydroxide poses problems, however, due to it dissolution which can create defects in the final restoration. Medina et al. (2002) investigated the pulp response to direct pulp capping with one-bottle adhesive systems without the traditional usage of calcium hydroxide. The authors concluded that the pulpal response depended on the brand of the adhesive system used. Some adhesives performed poorly by having significantly more inflammation and less reparative dentin after 90 days than the control, calcium hydroxide. While other adhesives, such as Single Bond used often at the University of Minnesota School of Dentistry, had acceptable results with none to mild inflammation of pulpal tissues and formation of reparative dentin. However, none of the adequate one-bottle systems provided the level of healing as the calcium hydroxide control group in the Medina et al. study. Thus until adhesive products can perform at the level of calcium hydroxide, it will be up to the clinician to utilize his/her clinical judgment as to which method of direct pulp capping is most appropriate for each individual situation.

Technique:
The first step in the composite restoration process is to select the shade of the restorative material. The shade should be selected while the tooth is still moist, i.e. before rubber dam placement. Place the rubber dam after local anesthetic to give adequate isolation for bonding in a dry field. Proper local anesthetic administration is dictated according to the area of restorative procedure. The tooth preparation for severe to moderate caries using composite resin is lesion specific. The prep is extended to the degree of caries involvement or to a depth where proper bonding and sealing of caries can be accomplished. Caries can be removed with a round bur or 330 bur. Dental hand instruments can also be used to remove caries to a degree that meets the practitioner's satisfaction. The edges of the preparation are then beveled. "Bevels in enamel provide more area for acid etching and bonding and has been shown that etching at transversely exposed enamel results in a bond that is significantly greater than that attained with a longitudinal etching pattern" (Schwartz et al. 1996). A disadvantage of beveling is that you expose thin portions of composite to occlusal stresses. With adequate bonding, there is no need to remove unsupported enamel. It is recommended that surfaces are gone over with a fine diamond in order to open dentinal tubules and enamel rods to allow access of the adhesive to bond deeper and closer with the dentin. If the proximal wall of the tooth has been removed due to the extent of the preparation, the next step is to apply the matrix band. The band functions to prevent etching of the adjacent tooth and to give proper contour to the restoration. It is also helpful to place a wooden wedge in areas where interproximal contacts need to be restored. This will help to ensure a tight contact, which can be very tough to accomplish when using composite resin. The entire preparation is etched using 35% phosphoric acid for 15 seconds and then thoroughly rinsed. "Recently, most marketed adhesive systems have utilized concentrations of phosphoric acid over 30% to etch cavity surfaces for 15 seconds, in order to optimize enamel etching" (Nakajima, 2000). "The determination to use etchant exclusively or in combination with a preparation is based on: 1. The location and size of the pulp. This may discourage the use of some preparation forms, with the exception of those limited to enamel. 2. The incisal or occlusal involvement. Acid etching by itself will not be able to support restorations that are subject to intense forces. The etchant creates peaks and valleys in the enamel, which allows for mechanical interlocking of the resin into the surface irregularities. The resin "tag" then produces a much improved bond of the resin to the tooth" (Baum et al. 1995). After the acid has been rinsed away, the excess water is dried off with the air/water syringe. The tooth should not be dried to the point of desiccation, but rather the tooth surface should be left moist. The appearance of the etched surface should appear frosty white.

The choice of bonding agents can be a very tedious process. According to Combe there are five benefits of adhesion. The first benefit is to reduce the dependence on mechanical retention. The next benefit is to eliminate the amount of tooth preparation. The third benefit is to eliminate micro leakage. The fourth is to seal the dentinal tubules to eliminate post-operative sensitivity. Lastly, the tooth is reinforced (Combe et al, 1999). There are four types of bonding systems available based on the number of steps involved in the application according to Combe. Combe lists the bonding systems as, Type I which involves four steps. The tooth is conditioned, washed, primed, and then the adhesive is applied. Type II consists of a three step process. The tooth is conditioned, washed, and a combined primer-adhesive is applied. In Type III, a combined conditioner-primer is applied followed by the application of the adhesive. Type IV involves only one step in which the conditioner-primer-adhesive are all combined and applied at the same time (Combe et al., 1999).

The university clinics use the single bond system by 3M ESPE, which is a type II bonding agent. After etching, two coats of single bond adhesive are applied to the enamel and dentin and dried gently for 2-5 seconds, according to the manufacturer's instructions. An area of controversy with bonding is the strength of the bond when carious dentin is left in the preparation. Nakajima et al. in 2000 found that Single Bond had a slightly lower bond strength over caries as compared to non-carious dentin. As expected, the adhesion when bonding to carious dentin is weakened because of the lack of sound tooth structure. However, the group also found that the bond strengths were the highest ever recorded, indicating a significant improvement in bonding formulations" (Nakajima et al., 2000). Another area of concern is the fact that caries causing bacteria are being left inside the restoration. Studies have shown that, "bonded and sealed composite restorations placed over frank cavitated lesions arrested the progress of these lesions over a period of ten years" (Mertz-Fairhurst, 1998). This is possible because the restoration is sealed due to the solid bonding of the adhesive to the remaining structurally sound preparation, thus depriving the cariogenic bacteria of substrate.

The placement of the composite material, such as Filtek Z250 (3M ESPE) is most successfully done in an incremental fill. "Incremental placement of the composite is necessary to ensure polymerization in deep restorations" (Jerdrychowski, 1998). 3M Espe recommends that Z250 restorative material be placed in increments less than 2.5mm (2002). Light cure each increment for 20 to 40 seconds according to the manufacturer's instructions. "The use of high-intensity light-curing units has been shown to negatively affect the integrity of the restoration-cavity interface. It has been pointed out that light initiated polymerization at low intensity followed by light curing at full intensity, may lead to light-cured composite restorations with improved marginal adaptation" (Liebenburg, 2000). So in other words, longer curing at lower intensities can enhance the marginal adaptation of your restorations.

Once the composite has been cured, "The matrix is removed to permit immediate interproximal insertion of a finishing strip, the use of which completes the interproximal fine finishing of the critical inaccessible gingival margin" (Liebenburg, 2000). The occlusal surface is finished using appropriate finishing instruments, finishing burs, etc. Interproximal surfaces can be finished with Sof-Lex discs and finishing strips. "The finishing process readily creates micro structural defects that decrease wear resistance appreciably" (Liebenburg, 2000). Therefore, it is important to get ideal anatomical contours before curing to ensure minimal finishing and to eliminate micro-defects.

Comparison
Since its development and introduction to the dental community in the late 1960s, the use of composite resin in posterior restorations has met much resistance. Granted, the vast majority of dentists agree that composite "tooth-colored" materials are superior esthetically to amalgam, there are concerns regarding the issues of wear resistance, marginal integrity, biocompatibility, and post-operative sensitivity. Amalgam advocates are reluctant to concede that composite restorations measure up to the well-researched, clinically-proven physical properties of amalgam. As a relatively new and developing material, there have been vast improvements over the early composite resin formulations with the advent of bonding systems and modification in the particle size of fillers. Current composite materials are proving to be competitive, if not superior, to amalgam, thus making it essential for dentists to become educated on their use (Christensen, 1998).

Wear-resistance and longevity are issues of major concern regarding the use of composites in posterior restorations. Early composites of the 1970s did indeed show excessive wear such as loss of anatomic form and interproximal contacts, ultimately leading to restoration failure. However, dramatic enhancements in the composite formulations have significantly altered the clinical performance of composite materials. Even so, 1998 study found the average wear of a hybrid composite to be approximately 30 mm per year more than enamel on tooth occlusal surfaces while amalgam was only 10 mm a year more than enamel (Christensen, 1998). Likewise, amalgam restorations tend to last longer with a mean age before replacement of 15.0 years compared to 8.2 years for composite (Mjör, 1998).

However, it must be considered that improvements to composite materials have been made in the last five years, and unfortunately, longitudinal data of these current materials will not be available for several years. A more promising review conducted by Hickel, et al. in 2000 analyzed clinical studies pertaining to the longevity of direct restorations in Class I and II cavities of permanent posterior teeth with at least three years duration. The results of this review show composite to have a lower median annual failure rate (2.2%) compared to amalgam (3.3%). Furthermore, neither the Mjor, et al. nor Hickel, et al. study demonstrated excessive wear as a significant reason for replacement of existing composite restorations. Hence, composite materials should not be disregarded as an alternative to amalgam based upon wear characteristics.

Another topic of interest concerning composite restorations is marginal integrity. The most common reason for failure of posterior composite resin restorations is microleakage. Poor marginal adaptation due to polymerization shrinkage results in gaps between cavity walls and the restorative material. This in turn allows bacterial and fluid penetration (microleakage) and ultimately leads to secondary caries and clinical failure (Ferdianakis, 1998). Nevertheless, several studies suggest that composite materials provide a better marginal seal than amalgam. For instance, Duncalf and Wilson (2001) found composite to have a significantly greater percent of perfect margins on the buccal, lingual, and cervical surfaces of a conservative Class II proximal box compared to amalgam. Consequently, it is logical to assume that as dentists improve their composite-placement techniques, the number of restorative failures due to microleakage and secondary caries will decrease appreciably. Amalgam, on the other hand, is not likely to improve its marginal adaptation since placement techniques and material composition have not changed greatly in recent years.

Additionally, the biocompatibility of composite resins must be evaluated relative to amalgam. Due to the recent development of composites, there are few existing studies that assess biocompatibility, yet none of those available indicates an unacceptable risk to the patient. Bisphenol A, a component of Bis-GMA composite, may exert a biological reaction comparable to estrogens by binding to estrogen receptors. One study found that a single fissure sealant released enough bisphenol A to cause estrogenic activity (Olea et al., 1996). However, the amount of bisphenol-A released was less than 1.5% of the allowed daily intake. Hence, the risk of composite materials is analogous to the trace amounts of mercury released from amalgam. Both appear to be inconsequential to a patient's health (Schmalz, 1998).

The pulpal response to composite versus amalgam restorations is also a topic of interest. The lack of adverse pulpal reaction to amalgam is apparent since it has been used for over one hundred years without an associated risk of pulpal necrosis. However, the acid-etch technique and monomeric components of composite justifiably raise concern. The removal of the dentin smear layer through etching opens the dentinal tubules, thus providing a passageway for the cytotoxic components of composite to the pulp. Nonetheless, inflammatory reactions and tissue necrosis have not been demonstrated. Instead, injurious pulpal responses are likely attributable to the trauma associated with tooth preparation and excessive loss of tooth structure. These risks are just as likely, if not more so, in amalgam restorations because of the extended cavity preparations (Bergenholtz, 2000).

Some dentists claim that their patients have an increased incidence of post-operative sensitivity following composite restorations compared to amalgam restorations. Since amalgam conducts heat better than composite and it has previously been established that composite restorations are biocompatible with pulp tissue, the increase in sensitivity is probably explained by substandard placement technique. Many errors can potentially result in tooth sensitivity. For example, primers "wet" the dentinal canals, making them receptive to the bonding agent. If inadequate amounts of primer are used, poor bonding and sensitivity results. Similarly, tooth desiccation, inadequate curing light intensity, failure to use incremental filling, and excessive finishing procedures may all cause post-operative pain for the patient (Christensen,1996). Accordingly, post-operative sensitivity will almost certainly be reduced considerable as dentists become more comfortable with and knowledgeable on proper composite placement technique.

In summary, concerns regarding the wear resistance, marginal adaptation, biocompatibility, and post-operative sensitivity are slowly dissipating as composite resin restorative materials continue to improve and dentists become more practiced in placement technique. These improved physical properties in addition to the benefits of conservative preparations and more esthetic outcomes make composite materials the restoration of choice, even in high-stress posterior teeth.

Outcomes
Numerous studies have been performed that have compared the bonding strength of composites to sound tooth structure. However, completely sound tooth structure is not always encountered when composite restorations are placed clinically. Typically, composite restorations are placed over varying degrees of decalcified dentin and over active cariogenic bacteria. The theories behind this strategy are meant to restore and protect the tooth at different points of susceptibility. These include starving the cariogenic bacteria of nutrients, sustained release of antimicrobial chemicals, and reinforcing weakened tooth structure. The early work of infiltrating materials into carious lesions involved using resocrinol-formaldehyde materials (Robinson, 1976). Due to the detrimental effect these materials had on living tissue, materials that are more compatible to the oral environment were used to bond to carious dentin. Recently, more studies have been published which show the advantages and disadvantages of bonding to carious dentin.

In order for any material to bond to dentin, or carious dentin, it must be able to penetrate into the microstructure of the dentin. This can be measured in vitro with the amount of a liquid an extracted tooth can take up before and after coating with an adhesive. Robinson et al. (2001) called this the relative accessible pore volume, and it was used to measure the ability of an adhesive to penetrate into dentinal tubules. This was expressed as a percentage based on the amount of liquid the tooth could take up before and after binding. All of the adhesive polymers used were able to reduce the accessible pore volume by 50-75% after one application on carious dentin, which suggests they all penetrate into the caries affected area. After a second application, each of the adhesives again reduced the accessible pore volume by another 25%. The third application did not show a statistically significant reduction of accessible pore volume leading to the assumption that two applications of adhesive is probably ideal for most adhesives. The adhesives used in this study included Scotchbond Multipurpose, Gluma 2000, Allbond 2, and Amalgambond Plus. Cyanoacrylate was also used and showed an increase in accessible pore volume, meaning that not only did it not penetrate, it increased the porosity of the treated dentin. The control in this study was caries lesions that were not treated.

As the previous paragraph stresses, it is imperative that the adhesive be able to successfully penetrate the dentin microstructure to form an adequate bond. However, the microstructure of carious dentin differs from that of non-carious dentin. Carious dentin is partially demineralized, and some of the minerals precipitate into the dentin tubules. This can occlude the tubules and interfere with resin tag formation in the hybrid layer. Acid etching is necessary to clear out the tubules and appears to be the crucial step in bonding to carious dentin. Yoshiyama, et al. (2000) tested the resin-dentin interface morphology of two bonding systems (Single Bond and Fluorobond) to carious dentin using SEM. Single Bond is a primer-adhesive single bottle product and was used in conjunction with a 35% phosphoric acid gel etchant. Fluorobond is a self-etching/self-priming adhesive system, whose etchant is less acidic than 35% phosphoric acid. The 35% phosphoric acid solution used with Single Bond was sufficient to remove most of the mineral deposits in the tubules, resulting in the successful formation of resin tags. Conversely, the Fluorobond self-etching adhesive was unable to successfully penetrate the mineral-occluded tubules of carious dentin, resulting in no resin tag formation.

Nakajima, et al. (2000) found similar results in their study using One-Step and Single Bond, each following etching with 10% and 32-35% phosphoric acids. Their results showed that microtensile bond strengths of One-Step with 10% acid etch was lower on cariously-affected dentin compared to normal dentin (36.9 MPa vs. 47.7 Mpa, respectively). However, the bond strength differences for One-Step on carious and normal dentin disappeared when etched with 35% phosphoric acid. Single Bond showed lower bond strengths in carious dentin regardless of the acid etchant concentration. However, it appears that the concentration of acid etchant is the most important determinant of eventual bond strength. Both the Yoshiyama, et al. and Nakajima, et al. studies indicate that 35% phosphoric acid is necessary to adequately etch carious dentin.

Microtensile bonding strengths can also vary between moist and dry dentin. The manufacturers of Single Bond recommended using it on moist dentin, and Fluorobond is recommended for use on dry dentin. Yoshiyama, et al. discovered that the highest bond strengths were from Single Bond bonded to moist normal dentin (46.0 MPa), followed by Fluorobond dry normal dentin (28.2 MPa), Single Bond on moist carious dentin (27.0 MPa), Single Bond on dry normal dentin (26.4 MPa), Single Bond on dry carious dentin (18.1 MPa), and Fluorobond on dry carious dentin (17.6 MPa). Therefore, the microtensile bond strengths were consistently reduced for Single Bond and Fluorobond when used on carious versus normal dentin. However, each product also showed reduced bond strengths when the moisture content of the dentin surface differed from the manufacturer recommendations.

Another factor for successful bonding of composite to caries lesions is the inhibition of bacteria in the area being restored. One mechanism for the inhibition of bacteria is achieved by the bonding of the composite restoration to the dentin. The resulting physical barrier prevents nutrients from reaching the inner regions of the lesion. A recent study assessed the abilities of four commercially available adhesives to be bactericidal. Single Bond and Prime and Bond did not significantly reduce the counts of S. mutans, while Liner Bond did show a moderate amount of bactericidal activity. The bactericidal activity of these adhesives is related primarily to the acidity of each agent. Investigators recently studied the addition of bactericidal chemicals to the adhesives used in the bonding process. Imazato et al. (2002) studied the effect various bonding agents have on bacterial counts in in vitro caries lesions. The experimental chemical MDPB was also tested to assess its bactericidal activity and its ability to penetrate into carious dentin. The results show that MDPB containing primers are antibacterial against most species of cariogenic bacteria. This allows the adhesive to arrest existing lesions while not affecting bond strength or penetration into the lesion. Adhesives containing MDBP are still being investigated and may soon be commercially available.

Position Statement
It is our hope that through a review of this paper, your understanding of the use, selection, and placement technique of posterior composite restorations has improved. After the sizeable amount of research we did in order to present this paper to the class, we, as a group, have concluded that with proper placement technique, posterior composites are indeed a viable alternative to amalgam for posterior restorations of moderate to severe lesions. It is our belief that with the continued improved of composite resin restorative materials, the current trend of increased posterior composite placement will continue and eventually replace amalgam. One of the short-term goals of this paper is simply to gain an acceptance, from those unwilling to give up amalgam, of the many potential benefits composite restorations have to offer. Long-term goals include increased placement and improved physical properties of these posterior composite materials. In order for these goals to be achieved, the dental community needs to stay updated on current data pertaining to the wear-resistance, longevity, and biocompatibility of the newest composites. Additionally, it is important to be aware of the constantly increasing use of composite in posterior restorations, focusing especially on trends in the dental offices of the United States. To facilitate this data collecting, we are obligated as dentists to employ our learned skills toward interpreting the current literature, utilizing the principles of evidence-based research and the ability to "think outside the box." Next, we must apply this knowledge to our own practices by perfecting our composite placement technique, accepting composite as an adequate posterior restorative material, and critically evaluating new products as they are presented to us. This is a new and important responsibility placed upon us as we graduate from dental school, where all materials and methods are selected for us. Even so, the same evidence-based principles we are now so familiar with should be applied as we transition from school to private practice. It must be noted that there are potential risks associated with the use of posterior composite restorations since they are relatively new and do not have the benefit of decades of research as does amalgam. However, the concepts presented to you in this paper should help to convince you that the current data suggests that the proven benefits of composite far outweigh the potential risks. Therefore, it is the suggestion of this group that each of us become well-informed on the characteristics and use of composite for posterior restorations. In this manner, you will be better prepared to educate your patients on the issue, provide them with the most current restorative options, and guide them to making the best decision for their dental health.

Bibliography
Baum LP. Ralph W.. Lund MR. Textbook of Operative Dentistry. 3rd ed. W. B. Saunders Company, Philadelphia, PA. 661. 1995.

Bergenholtz G. Evidence for bacterial causation of adverse pulpal responses in resin-based dental restorations. Critical Review of Oral Biological Medicine. 11 (4): 467-480, 2000.

Christensen GJ. Tooth Sensitivity Related to Class I and II Resin Restorations. The Journal of the American Dental Association. 127(4): 497-8, Apr, 1996.

Christensen GJ. Amalgam Vs. Composite Resin: 1998. The Journal of the American Dental Association. 129(12): 1757-9, Dec, 1998.

Combe E, Burke T, Douglas W, Dental Biomaterials. Boston, MA. Kluwer Academic Publishers, 1999.

CRA status report: Class 2 Resins. CRA Newsletter. 26(9): Sept 2002.

Duncalf WV, Wilson HF. Marginal Adaptation of Amalgam and Resin Composite Restorations in Class II Conservative Preparations. Quintessence International. 32(5): 391-5, May, 2001.

Ferdianakis K. Microleakage reduction from newer esthetic restorative materials in permanent molars. The Journal of Clinical Pediatric Dentistry. 22(3): 221-229, 1998.

Heinikainen M, Vehkalahti M, Murtomaa H. Re-treatment decisions for failed posterior fillings by Finnish general practitioners. Community Dental Health. 19: 98-103, 2001.

Hickel R, Manhart J, Garcia-Godoy F. Clinical results and new developments of direct posterior restorations. American Journal of Dentistry. 13(Spec No): 41D-54D, Nov, 2000.

Imazato S, Walls AWG, Kuramato A, Shigeyuki E. Penetration of an antibacterial dentine-bonding system into demineralized human root dentine in vitro. Eur J Oral Sci. 110:168-174, 2002.

Jedrychowski JR. Bleier RG. Caputo AA. Shrinkage stresses associated with incremental composite filling techniques. Journal of Dentistry for Children. 65(2): 111-5, Mar-Apr, 1998.

Kwong SM, Cheung GSP, Itthagarun A, Smales RJ, Tay FR, Pashley DH. Micro-tensile bond strengths to sclerotic dentin using a self-etching and a total-etching technique. Dental Materials. 18, 359-369, 2002.

Liebenberg WH. The axial bevel technique: a new technique for extensive posterior resin composite restorations. Quintessence International. 31(4): 231-9, Apr, 2000.

Medina VO, Shinkai K, Shirono M, Tanaka N, Katoh Y. Histopathologic study on pulp responses to single-bottle and self-etching adhesive systems. Operative Dentistry. 27: 330-341, 2002.

Mertz-Fairhurst EJ. Curtis JW. Ergle JW. Rueggeberg FA. Adair SM. Ultraconservative and cariostatic sealed restorations: Results at year 10. JADA. 129: 55-66, Jan, 1998.

Mjör IA. Moorhead JE. Selection of restorative materials, reasons for replacement, and longevity of restorations in Florida. Journal of the American College of Dentists. 65(3): 27-33, Fall, 1998.

Nakajima M. SanoH. Urabe I. Tagami J. Pashley DH. Bond strengths of single-bottle dentin adhesives to caries-affected dentin. Operative Dentistry. 25(1):2-10, Jan-Feb, 2000.

Olea N, Pulgar R, Perez P, Olea-Serrano F, Rivas A, Novillo-Fertrell A, Pedraza V, Soto AM, Sonnenschein C. Estrogenicity of resin-based composites and sealants used in dentistry. Environmental Health Perspectives. 104(3): 298-305, Mar, 1996.

Pitts NB. Clinical diagnosis of dental caries: A European perspective. Journal of Dental Education. 65(1): 972-978, Oct, 2001.

Robinson C, Brookes SJ, Kirkham J, Wood SR, Shore RC. In vitro studies of the penetration of adhesive resins into artificial caries-like lesions. Caries Research. 35:136-141, 2001.

Schmalz G. The biocompatibility of non-amalgam dental filling materials. European Journal of Oral Science. 106(2 Pt 2): 696-706, Apr, 1998.

Schwartz RS. Summitt JB. Robbins JW and Santos Jd, Jr. Fundamentals of Operative Dentistry A contemporary approach. Quintessence Publishing Co, Inc. Chicago. 424. 1996.

Taskonak B, Sertgoz A. Shear bond strengths of saliva contaminated Œone-bottle'. Journal of Oral Rehabilitation. 29: 559-564, 2002.

Turkun S, Aktener O, Twenty-four-month clinical evaluation of different posterior composite resin materials. JADA. 132(2):196-203, Feb 2001.

Wilder A, May K, Bayne S, Taylor D, Leinfelder K, Seventeen-year clinical study of ultraviolet-cured posterior composite Class I and II restorations. Journal of Esthetic Dentistry. 11(3):135-42, 1999.

Yoshiyama M, Urayama A, Kimochi T, Matsuo T, Pashley DH. Comparison of conventional self etching adhesive bonds to caries-affected dentin. Operative Dentistry 25:163-169, 2000.

Yoshiyama M, Tay FR, Doi J, Nishitani Y, Tamada T, Itou K, Carvalho RM, Nakajima M, Pashley DH. Binding of self-etch and total-etch adhesives to carious dentin. Journal of Dental Research. 81(8): 556-560, 2002.

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