ReviewAdhesive Dentistry and Endodontics: Materials, ClinicalStrategies and Procedures for Restoration of AccessCavities: ...
Review      A bonded material such as composite resin or glass ionomer ce-               eugenol materials tend to leak mo...
Reviewthe chances of contamination of the obturating material, a barrier may              specific challenges which requir...
ReviewFigure 3. SEM of etched porcelain. (Courtesy of Dr. Bart VanMeerbeek, Leuven,Belgium.)                              ...
Reviewprocedure has never gained popularity. Metal primers are an alternativethat enhances the bond between metal and resi...
Reviewclinical studies with the “self etching” adhesive systems. The three step        the order of 8 Mpa. But unlike resi...
Reviewtion of access cavities, but also to the obturating materials that utilize           reverse the effects of the sodi...
ReviewFigure 8. (A) The access cavity is clean and ready to restore. (B) There was 10% hydrofluoric acid applied to the po...
ReviewFigure 8 (continued). (E) A dentin primer is applied to all internal surfaces and air dried, and a dentin adhesive i...
ReviewFigure 8 (continued). (I) Ocre colored modifiers are placed in the grooves. (J) Cusp inclines and triangular ridges ...
Reviewdual-cure composites that have not been light activated (126, 175–                 8. Apply a dentin primer and adhe...
Review   12. Contour and adjust the occlusion.                                                     15. Ricucci D, Grondahl...
Review       adhesives, glass ionomer and resin-modified glass ionomer cements and a com-              77. Calamia JR. Etc...
Adhesive dentistry in endodontics part 1
Adhesive dentistry in endodontics part 1
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Adhesive dentistry in endodontics part 1

  1. 1. ReviewAdhesive Dentistry and Endodontics: Materials, ClinicalStrategies and Procedures for Restoration of AccessCavities: A ReviewRichard S. Schwartz, DDS, and Ron Fransman, DDSAbstractThe complexity of restorative dentistry has increasedgreatly in recent years, with the myriad of productsused in “adhesive dentistry.” So too has the “simple” A t the tomb of the unknown endodontist, there is a plaque that reads “Root canal treatment is not complete until the tooth has been restored.” A recent article reviewed the overall topic of restoration of endodontically treated teeth (1). This reviewmatter of restoring access cavities after completion of will address in detail the important issues when restoring access cavities through nat-endodontic treatment. This review discusses current ural tooth structure and restorative materials with emphasis on major decision makingmethods of “bonding” to tooth structure, ceramic ma- elements, material selection and clinical procedures. It will focus on those aspects ofterials, and metals, with emphasis on those aspects adhesive dentistry that are important and unique to endodontics.that are important to endodontics. Specific materials,procedures and major decision making elements are Contamination of the Root Canal Systemdiscussed, as well as how to avoid problems in com- One of the primary goals of root canal treatment is to eliminate bacteria from thepatibility between endodontic and restorative materi- root canal system to the greatest possible extent (2, 3). Bacteria have been shown to beals. the etiology for apical periodontitis (4) and to be the cause of endodontic failure (2, 3,Key Words 5). One of the goals in restoring of the tooth after root canal treatment should be to prevent recontamination of the root canal system. Gross contamination can occurAccess cavities, adhesive dentistry, endodontics, restor- during the restorative process from poor isolation or poor aseptic technique. Contam-ative dentistry ination can also occur from loss of a temporary restoration or if leakage occurs. The same things can occur with a “permanent” restoration, but “permanent” materials tend to leak less than temporary materials (6). Exposure of gutta-percha to saliva in the pulp Dr. Schwartz runs a private practice limited to Endodon- chamber results in migration of bacteria to the apex in a matter of days (2, 7–9).tics, and is Clinical Assistant Professor, UT Health Science Endotoxin reaches the apex even faster (10).Center at San Antonio, San Antonio, TX. Dr. Fransman runs aprivate practice limited to Endodontics, Amsterdam, Nether- The importance of the coronal restoration in successful endodontic outcomes islands. widely accepted and has been supported by studies by Ray and Trope (11), Hommez et Address requests for reprints to Dr. Schwartz, San Antonio, al. (12), Tronstad et al. (13), Iqbal et al. (14), and Siqueira et al. (2). However, studiesTX 78257; E-mail: by Riccuci et al. (15), Ricucci and Bergenholz (16), Heling et al. (17), and Malone et Copyright © 2005 by the American Association ofEndodontists al. (18) indicate that contamination may not as important a factor in failure as is commonly believed. Therefore, it must be concluded that the significance of bacterial contamination as a cause of endodontic failure is not fully understood. Because there is clearly no benefit to introducing bacterial contamination into the root canal system, and since it may be a contributing factor in endodontic failure, a basic premise of this review will be that every effort should be made to prevent contamination. Temporization To minimize the likelihood of contamination, immediate restoration is recom- mended upon completion of root canal treatment (19 –21). When immediate restoration is not possible, and the tooth must be temporized, a thick layer of temporary material should be used, preferably filling the whole chamber. The majority of restorative dentists prefer a cotton pellet in the chamber, however (22). If a cotton pellet or sponge is to be use, orifice barriers are recommended, to provide a second layer of protection against contamination in addition to the temporary material at the occlusal surface. Recommended procedure for placing orifice barriers: 1. Countersink the orifice with a round bur. 2. Clean the orifices and floor of the pulp chamber thoroughly with alcohol or a detergent to remove excess cement and debris. Air abrasion provides a dentin surface that is free of films and debris. 3. Place a temporary or “permanent” restorative material in the orifices and over the floor of the chamber.JOE — Volume 31, Number 3, March 2005 Restoration of Access Cavities 151
  2. 2. Review A bonded material such as composite resin or glass ionomer ce- eugenol materials tend to leak more, they possess antimicrobial prop-ment is preferred (23–27). Temporary materials may also be used erties, making them more resistant to bacterial penetration (21, 34,(28). Mineral trioxide aggregate (MTA) may also be used (29). There 41). Both materials are simple to use. One study reported less leakageis probably some benefit to using a material that is clear so that the with the use of two materials in combination (42).restorative dentist can see the underlying obturating material if re-entry Resin based temporary materials must be bonded to provide anis needed into the canal system (1) (Fig. 1). effective seal, because they undergo polymerization shrinkage of 1 to Results varied in studies that evaluated temporary materials for the 3% (30, 43). This is offset somewhat by the fact that they swell as theyaccess cavities (21, 30 –36). The most common materials tested were absorb water (30). Generally, bonded resin materials provide the bestzinc oxide eugenol (such as IRM, Dentsply Int.), zinc oxide/calcium initial seal, but lack antimicrobial properties (30). They require moresulfate (Cavit, Premier Corp.) or resin based materials including com- steps and more time to place than materials such as IRM or Cavit.posite resin and resin modified glass ionomer materials. Generally, all Bonded resins are recommended for temporization that is likely to lastof the temporary materials were adequate if placed in a thickness of 3 more than 2 to 3 wk (42, 44). Resin modified glass ionomer materialsmm or greater (21, 33–36). are also a good choice for long term temporization, because they pro- All temporary materials leak to some extent (20, 21, 37– 40). The vide a bond to dentin and enamel, and many have antimicrobial prop-zinc oxide/calcium sulfate materials are more resistant to microleakage erties (44).than the zinc oxide eugenol materials (21, 34), probably because of Teeth requiring temporary post/crowns are a particular challenge,setting expansion and water sorption (33). Although the zinc oxide because of the difficulty in obtaining a good seal (45, 46). To minimizeFigure 1. (A) The pulp chamber has been thoroughly cleaned. (B) There was 37% phosphoric acid applied to the orifices and floor of the chamber for 15 s. (C) Thefloor and orifices are sealed with unfilled resin. (Courtesy of Dr. Fred Barnett, Philadelphia.)152 Schwartz and Fransman JOE — Volume 31, Number 3, March 2005
  3. 3. Reviewthe chances of contamination of the obturating material, a barrier may specific challenges which require specific strategies and materials. Of-be placed over it with a self-curing material. The post space should be ten the access opening is prepared through two or three different sub-restored as soon as possible and it may be beneficial to flush the post strates. The structural integrity of the tooth may also influence thespace with an antimicrobial irrigant when the temporary post is re- choice of restorative materials. Each substrate will be addressed sepa-moved. rately. Restoring Access Openings When an access opening is made through an existing restoration, Bonding to Enamelseveral things should be considered. Removal of all existing restorations Enamel is often present along the margins of access preparationsis desirable if possible, because it allows more complete assessment for of anterior teeth. The resin bond to etched enamel is strong and dura-the presence of cracks and caries (47). This is particularly recom- ble. The technique dates back to 1955 (58). Etching of enamel with anmended for old class 1 and class 2 restorations, because they are likely acid such as 30 to 40% phosphoric acid results in selective dissolutionto be removed later anyway, in the process of preparing the tooth for a of the enamel prisms and creates a surface with a high surface energycrown. Magnification and caries detector are helpful in identifying that allows effective wetting by a low viscosity resin. Microporosities arecracks and for complete removal of caries (48). created within and around the enamel prisms that can be infiltrated with If the existing restoration is a crown or onlay that appears to be resin and polymerized in-situ (59). These “resin tags” provide micro-clinically satisfactory and replacement is not planned, the chamber and mechanical retention. Bond strengths are typically in the range of 20internal restorative materials should be examined carefully with mag- megapascals (Mpa) (60). Megapascals are a measure of the force pernification. Caries detector should be painted on the internal tooth sur- unit area that is required to break the bond. Self-etching adhesive sys-faces. Any areas stained by the caries detector, particularly adjacent to tems, which will be discussed in the section on bonding to dentin, etchrestorations, should be examined carefully for softness or gaps (Fig. 2). ground enamel fairly well, but do not etch unground, aprismatic enamelCaries detector may also stain sound areas of dentin that have decreased effectively (61– 63). Therefore, enamel margins should be beveledmineral content (49). The key to the presence of caries is determined by when using self-etching adhesive systems. It is critical to prevent con-whether the stained areas are hard or soft. Many times caries can be tamination of etched enamel with blood, saliva or moisture (64). Poorlyidentified internally, necessitating replacement of the crown. etched enamel leads to staining at the margins of the restoration (65). Access openings made through an existing restoration results in A good enamel bond protects the underlying dentin bond which is lessloss of retention (50 –52) and strength (53). When the access opening durable (66).is restored, loss of retention is reversed (51, 52). If a post is added,additional retention is gained (51). Ideally, we would like to restore access cavities with a restorative Bonding to Metal-Ceramic and All-Ceramicmaterial that provides a permanent, leak proof seal. Unfortunately, no Restorationssuch material is available. All materials that we use and restorations that Access cavities are often made through metal-ceramic or all-ce-we place leak to some extent. This includes intracoronal restorations ramic materials, so attaining an effective, durable bond is importantincluding bonded resin and glass ionomer materials (38, 54) as well as when restoring them. The literature is unambiguous that the bestthe metal or ceramic extra-coronal restorations (55, 56). To minimize method to bond to porcelain is to first roughen the surface by acidleakage, bonded restorations are recommended, regardless of the re- etching and then apply a silane coupling agent, followed by the resinstorative material (6, 57). (67–70). Bond strengths of 13 to 17 Mpa have been reported, and Access openings are made through a number of different restor- failure is often cohesive within the porcelain, meaning that the interfa-ative materials, including gold alloys, base metal alloys and porcelain, as cial bond strength exceeds the strength of the porcelain itself (71–73).well as enamel and dentin. Bonding to each of these substrates present Bonding to porcelain was initially developed as a method for repair of fractured metal-ceramic crowns. Improvements in the technique al- lowed porcelain veneers to become a common clinical procedure. Etched ceramic materials form a strong, durable bond with resin (74). Micro mechanical bonding can be attained by roughening the porcelain with a bur, air-abrasion or etching with hydrofluoric acid. However, acid etching is the most effective method (73, 75, 76). The first to introduce acid etching of porcelain was Calamia in 1983 (77). Adhesion between the resin and porcelain may be enhanced by the use of a silane-coupling agent. Silane acts as a surfactant to lower sur- face tension and forms double bonds with OH groups in the porcelain, forming a siloxane bond. At the other end of the silane molecule is a methacrylate group that copolymerizes with resin. The use of a silane- coupling agent with porcelain was first described by Rochette in 1975 (78). Hydrofluoric Acid Hydrofluoric acid provides greater surface roughness to porcelain than air abrasion or roughening with a bur (75). It works by dissolving the glass particles (leucite) within the porcelain (Fig. 3). Most of theFigure 2. Caries detector was applied to the inside of an access cavity. Note how porcelains used in metal-ceramic restorations are feldspathic porce-the caries detector accentuates the caries under the composite buildup. (Cour- lains that contain leucite. Some ceramic materials, such as low fusingtesy of Dr. Gary Carr, San Diego.) porcelains, do not contain leucite and are not etched effectively byJOE — Volume 31, Number 3, March 2005 Restoration of Access Cavities 153
  4. 4. ReviewFigure 3. SEM of etched porcelain. (Courtesy of Dr. Bart VanMeerbeek, Leuven,Belgium.) Figure 4. Most restorative composites are too translucent (gray) to provide ahydrofluoric acid (79). However, hydrofluoric acid is effective with good match when restoring access cavities in metal-ceramic crowns.most of the current ceramic restorative materials (80 – 83). Hydrofluoric acid is usually provided in a 10% concentration in asyringe. It is very important to follow the manufacturer’s instructions, as are composite resins that contain opaquers. They may be covered withan application time that is too short will produce an inadequate etch, more translucent composite materials. Several composites are availablewhile an application time that is too long may render the porcelain that are quite opaque and work well when restoring access cavities inbrittle and thus more prone to fracture (84). metal-ceramic crowns. Composite stains can be used to accentuate pits and fissures to further enhance the cosmetic result (Fig. 5).Silane Silane acts as a “coupling agent” enhancing the bond between the Bonding to Metalresin and ceramic materials. It is supplied premixed or as a two bottle The metal portion of metal-ceramic crowns is not usually signifi-system that is mixed at the time of use. It is applied to the etched surface cant when restoring access openings, so no extra procedures are nec-and must be thoroughly air dried (85). A low viscosity resin adhesive is essary to deal with it. However, for crowns in which all or part of thethen flowed over the surface and polymerized. Once again, it is very occlusal surface is metal, adhesion may be desirable. Adhesion to metalimportant to follow the manufacturer’s instructions. is generally obtained by mechanical means. Surface roughness may be Silane has a limited shelf life. Storage in the refrigerator will extend created with a bur or air abrasion, which provides micromechanicalits useful life, but it should be used at room temperature (86). The two retention (89). Chemical adhesion is also possible with metals that formbottle silanes have the longest shelf life (71). Silane that is past the an oxide layer (90). Silane has no effect on bonding to metal (91).expiration date or that contains precipitates should be discarded (86). Several studies have shown tin plating of metal enhances mechan- ical retention (92–96). Chromium plating also works well (96). PlatingAir Abrasion devices are available that can be used intraorally. Although effective, this Air abrasion is sometimes recommended to clean the porcelainand provide surface roughness. Several companies sell “micro-etchers”that can be used chairside. Aluminum oxide particles are sprayed ontothe surface at about 80 psi. Fifty micron particles have been shown toproduce a more retentive surface than 100 ␮m particles (87). Twostudies reported that air abrasion has a negligible effect on bondstrength, however (76, 88). Etching and application of silane are thetwo most important steps.Cosmetics When restoring the access cavity of a ceramic crown, it is often achallenge to produce a good cosmetic result. Many times it is difficult tomask the underlying metal of a metal-ceramic crown. This is particu-larly true if the porcelain is thin. It is not uncommon to see the metalshowing through the composite. The second challenge is to match theoptical properties of the porcelain. This is true for metal-ceramiccrowns as well as all-ceramic crowns. Most composites are too low invalue (too gray and translucent) to effectively match the surroundingporcelain (Fig. 4). Several products are available that may be used to mask the un- Figure 5. With knowledge of color, translucency and occlusal anatomy, beau-derlying metal before the restorative composite is placed. Most of these tiful results are achievable when restoring access cavities with composite resins.154 Schwartz and Fransman JOE — Volume 31, Number 3, March 2005
  5. 5. Reviewprocedure has never gained popularity. Metal primers are an alternativethat enhances the bond between metal and resin. They have been shownto be effective and do not require any special equipment (97–99). Bonding to Dentin: Resin Materials Bonding to dentin with resin materials is more complex thanbonding to enamel or porcelain. Dentin consists of approximately 50%inorganic mineral (hydroxyapatite) by volume, 30% organic compo-nents (primarily type 1 collagen) and 20% fluid (100). The wet envi-ronment and relative lack of a mineralized surface made it a challengeto develop materials that bond to dentin. Current strategies for dentinadhesion were first described by Nakabayashi in 1982 (101), but hisideas were not widely accepted for a number of years. Nakabayashishowed that resin bonding to dentin could be obtained by applying anacid to expose the collagen matrix and dentinal tubules, applying ahydrophilic (“water loving”) resin material to the demineralized sur-face and polymerizing the resin in situ. The collagen matrix and dentin Figure 6. SEM of a demineralized specimen showing resin penetration into thetubules, to a lesser extent, provide mechanical retention for the resin. hybrid layer and dentinal tubules. (Courtesy of Dr. Bart VanMeerbeek, Leuven,Although not as durable and reliable as enamel bonding, steady im- Belgium.)provements have been made in dentin bonding and in simplifying den-tin-bonding procedures. Most in vitro studies of dentin bonding report on bond strengths, residual carrier/solvent is left behind (119), which makes the bondmicroleakage, or both. Like enamel, bond strengths are usually re- more subject to hydrolytic breakdown (119).ported in Mpa. Depending on the test method used, initial bondstrengths can be obtained that are equal or greater to those of etched “Self Etching” Adhesivesenamel. However, dentin bonding is not as durable as enamel bonding Most of the “self etching” products combine an acid with theor as stable. It is well documented that bond strengths decrease with primer. Rather than removing the smear layer, they penetrate through ittime and function. This has been shown in vitro (66, 102–109) and in and incorporate it into the “hybrid layer.” The acidic primer is appliedvivo (110, 111). Microleakage is probably a more important issue to to the dentin surface and dried with a stream of air. There is no rinsingendodontics than bond strength. None of the current adhesive systems step. A resin adhesive is then applied and polymerized, followed by theare capable of preventing microleakage over the long term (65, 112– restorative material.117). There is not a direct relationship between bond strength and The “self etching” systems can be categorizes as “strong” or “ag-microleakage (116). gressive” (pH Ͻ1), “moderate” (pH 1–2) or “mild” (pH Ͼ2) (59, Dentin adhesive systems utilize an acid as the first step of the 120, 121). The strong “self etching” systems form a hybrid layer ofbonding process to remove or penetrate through the smear layer and approximately 5 ␮m in thickness, similar to phosphoric acid, whereasdemineralize the dentin surface. The smear layer covers the surface of the mild systems form a hybrid layer of about 1 ␮micron (120, 121).ground dentin and consists of ground up collagen, hydroxyapatite, bac- There does not appear to be clinical significance to this difference interia, and salivary components (59). Most dentin adhesive systems can thickness, however (121). The “strong” systems generally produce abe categorized as “etch and rinse” or “self etching,” based on the acid superior bond to enamel than the “weak” systems (59), particularlyetching process (59). with unground enamel (61– 63). Dentin Adhesive “Generations”“Etch and Rinse” Adhesives Many of the “etch and rinse” adhesive systems require three steps Most of the “etch and rinse” adhesive systems utilize a strong acid (etch, primer, adhesive), and are known as “4th generation” adhesivesuch as 30 to 40% phosphoric acid. When phosphoric acid is applied to systems. The “generation” of a dentin adhesive generally follows thedentin, the surface is demineralized to a depth of about 5 ␮m. The acid order in which they were developed and each “generation” utilizesis rinsed off after about 15 s, removing the smear layer and exposing the different bonding procedures. The “5th generation” adhesive systemscollagen matrix and network of dentinal tubules for resin bonding. A are “etch and rinse,” followed by application of a combined primer andhydrophilic primer is then applied to the surface to infiltrate the colla- adhesive. These are sometimes referred to “single bottle” adhesive sys-gen matrix and tubules. The primer contains a resinous material in a tems. Some require several applications of the primer/adhesive, how-volatile carrier/solvent, such as alcohol or acetone, which carries the ever. The “6th generation” adhesives utilize an acidic (“self etching”)resinous material into the collagen matrix and dentinal tubules. The primer followed by an adhesive. The 5th and 6th generations are gen-surface must be wet (moist) for the primer to penetrate effectively. After erally two step procedures, while the 7th generation combines every-the primer is in place a stream of air is used to evaporate the carrier and thing (acid, primer and adhesive) into one step.leave the resin behind. A hydrophobic (“water hating”) resin monomer Many of the “self etching” products require fewer steps and less(adhesive) is then applied and polymerized, which adheres to the infil- time than the “etch and rinse” products, and are considered to be lesstrated resin from the primer. A “hybrid layer” or “interdiffusion zone” “technique sensitive” (59). There are still a number of questions aboutis formed that consists of resin, collagen and hydroxyapatite crystals them, however, such as the unknown effects of incorporating partially(59) (Fig. 6). It bonds the hydrophobic restorative materials to the dissolved hydroxyapatite crystals and smear layer into the hybrid layer.underlying hydrophilic dentin. Poor bond strengths and increased mi- There is also the question of how much of the carrier/solvent remainscroleakage result from excessive etching (118). The same is true if behind. Because they are relatively new, there are currently no long-termJOE — Volume 31, Number 3, March 2005 Restoration of Access Cavities 155
  6. 6. Reviewclinical studies with the “self etching” adhesive systems. The three step the order of 8 Mpa. But unlike resins, they form a “dynamic” bond. Asadhesive systems generally perform better in in vitro testing than the adhe- the interface is stressed, bonds are broken, but new bonds form. This issive systems that combine steps (59, 65, 66, 107, 121, 122), although the one of the factors that allow glass ionomer cements to succeed clini-differences lessen with time as the bonds degrade (66, 107). The “self cally, despite relatively low bond strengths. Other factors are low poly-etching” adhesive systems are also less effective than the “etch and rinse” merization shrinkage and a coefficient of thermal expansion that issystems when bonding to sclerotic dentin and caries effected dentin (123, similar to tooth structure. Some glass ionomer materials also possess124). They also have compatibility problems with some composite restor- antimicrobial properties (134 –136).ative materials, which will be discussed in the section on self-cure and When placing glass ionomer cements, the surface is cleaned anddual-cure composites. The single step (7th generation) adhesives are a then treated with a weak acid such as polymaleic acid (131). The acidfairly recent addition to the market. At this point in their development, they removes debris from the dentin surface, removes the smear layer, andproduce consistently lower bond strengths in vitro than the others (59, 107, exposes hydroxyapatite crystals. It creates microporosities in the hy-121, 125) and are not compatible with self-cure or dual-cure composites droxyapatite for mechanical retention, but there is minimal dissolution(126). Most of the current research is directed toward improving the per- (131, 133). Because glass ionomer cements rely on ionic bonding toformance of the simplified adhesive systems, and they will probably continue the hydroxyapatite, strong acids should be avoided because they causeto improve. Some of the common acronyms used in resin bonding are almost total elimination of mineral from the dentin surface (137).shown in Table 1. Examples of commercial dentin bonding systems are Traditional glass ionomer cements are not widely used for clinicalshown in Table 2. procedures because they set slowly and must be protected from mois- ture and dehydration during the setting reaction, which in many cases isWet Bonding not complete for 24 h. They are also relatively weak and generally not as Most adhesive systems utilize “wet bonding.” If the etched dentin esthetic as other restorative materials.surface is dried excessively, the collagen matrix collapses and preventseffective infiltration of the primer. The result is low bond strengths andexcessive microleakage (127–129). Excessive moisture has similar Bonding to Dentin: Resin Modified Glass Ionomernegative effects on adhesion (128, 129). An effective method to provide Materialsthe proper amount of moisture is to dry the surface thoroughly and then Resin modified glass ionomer (RMGI) materials were developedrewet it with a moist sponge, so that the surface is damp, but there is no to overcome some of the undesirable properties of the traditional glassvisible pooling (127, 130). ionomer cements. RMGI materials contain glass ionomer cement to which a light-cure resin is added. The purpose of the resin is to allowBonding to Dentin: Traditional Glass Ionomer Cements immediate light polymerization after the material is placed. The resin also protects the glass ionomer cement from dehydration, and improves Glass ionomer cements are made primarily of alumina, silica and the physical and mechanical characteristics and optical properties.polyalkenoic acid and are self curing materials. Most glass ionomer True RMGI materials utilize similar bonding procedures as glass iono-cements release fluoride for a period of time after initial placement. mer cements and do not require a dentin-bonding agent.They are the only restorative materials that depend primarily on a chem-ical bond to tooth structure (131). They form an ionic bond to thehydroxyapatite at the dentin surface (132) and also obtain mechanical Endodontic Issues in Dentin Bondingretention from microporosities in the hydroxyapatite (133). Glass iono- Some of the materials used in endodontics may have a significantmer materials form lower initial bond strengths to dentin than resins, on impact on the bonding process. These issues apply not only to restora-TABLE 1 Common abbreviations used in dental adhesive literatureBis-GMA Bisphenol glycidyl methacrylate Unfilled resin—The original acrylic matrix material in composite resinsEDTA Ethylenediaminetetracitic acid Chelating agent sometimes used to remove the smear layer and demineralize the dentinHEMA Hydroxyethyl methacrylate Low viscosity hydrophilic acrylic monomer used in dentin adhesive systems4-Meta 4-Methacryloxyethyl trimellitate anhydride Low viscosity acrylic monomer used in dentin adhesives. Also used for metal bondingMMA Methyl methacrylate Basic acrylic moleculeNPG-GMA N-Phenylglycine glycidyl methacrylate Low viscosity hydrophilic acrylic monomer used in dentin adhesivesPMDM Pyromellitic acid dimdiethylmethacrylate Low viscosity hydrophilic acrylic monomer used in dentin adhesivesTEG-DMA Triethylene glycol dimethacrylate Low viscosity hydrophilic acrylic monomer used in dentin adhesivesUDMA Urethane dimethacrylate Unfilled resin. Alternative composite matrix material for composites. Sometimes combined with Bis-GMATABLE 2. Selected dental adhesive systems th All-Bond 2 Three step, etch and rinse, ”4 generation“ Bisco OptiBond Total Etch Three step, etch and rinse, ”4th generation“ Kerr Scotchbond Multipurpose Three step, etch and rinse, ”4th generation“ 3M One Step Two step, ”single bottle,“ etch and rinse, ”5th generation“ Bisco Prime&Bond Two step, ”single bottle,“ etch and rinse, ”5th generation“ Dentsply Clearfil SE Two step, self-etching, ”6th generation“ Kuraray OptiBond Solo SE Two step, self-etching, ”6th generation“ Kerr Prompt L-Pop 2 One step, self-etching, ”7th generation“ 3 M/ESPE I-Bond One step, self-etching, ”7th generation“ Kulzer156 Schwartz and Fransman JOE — Volume 31, Number 3, March 2005
  7. 7. Reviewtion of access cavities, but also to the obturating materials that utilize reverse the effects of the sodium hypochlorite. A nonoxidizing irrigantadhesive resin technology, which will be discussed in a subsequent would also solve this problem. Sodium hypochlorite and EDTA have alsoarticle. been shown to reduce the tensile strength and microhardness of dentin (152). These are particularly timely issues for endodontics as adhesiveEugenol resin materials gain popularity as obturating materials. In endodontics, eugenol containing materials are widely used insealers and temporary filling materials. Eugenol is one of many sub- Other Materials Applied to Dentinstances that can prevent or stop the polymerization reaction of resins Other materials that are applied to dentin during endodontic pro-(138) and can interfere with bonding (139). If resin bonding is planned cedures have been tested for their effects on bonding. Not surprisingly,for a dentin surface that is contaminated with eugenol, additional clin- hydrogen peroxide leaves behind an oxygen rich surface that inhibitsical steps are needed to minimize the effects of the eugenol. The surface bonding (147, 148). Reduced bond strengths were shown after the useshould be cleaned with alcohol or a detergent to remove visible signs of of RC prep (Premier) (146). Electro-chemically activated water hassealer. Many temporary cements, whether they contain eugenol or not, gained a following as an irrigating solution. It probably reduces bondleave behind an oily layer of debris that must be removed before bond- strengths of adhesive resins because it has the same active ingredient asing procedures (140, 141). Air abrasion is an effective method for sodium hypochlorite, i.e. hypochlorous acid (153, 154). No loss ofcleaning the dentin surface (Fig. 7). Once it is clean, the dentin should bond strength is reported from chlorhexidine irrigation before resinbe etched with an acid, such as phosphoric acid and then rinsed. The bonding (147, 155, 156) or placement of resin-modified glass ionomeracid demineralizes the dentin surface to a depth of about 5 ␮m and materials (157). Caries detector did not affect resin bond strengthsremoves the eugenol rich layer. Several studies have shown that the (158, 159), but chloroform and halothane resulted in significant loss of“total etch” (three step) procedure allows effective bonding to eugenol bond strength (160).contaminated dentin surfaces (24, 142). An “etch and rinse” adhesivesystem should be used, because the “self etching” systems incorporatethe eugenol rich smear layer into the hybrid layer, rather than removing Restorative Materialsit. Eugenol has no effect on glass ionomer cements (143). Silver Amalgam Alloy Not surprisingly, silver amalgam alloy is the most common choiceSodium Hypochlorite for restoring access cavities in metal crowns (161). The clinical tech- Sodium hypochlorite is commonly used as an endodontic irrigant nique is simple, with few steps, and provides a durable restoration.because of its antimicrobial and tissue dissolving properties (144). “Bonded amalgam” is often recommended (57) in which a resin adhe-Sodium hypochlorite causes alterations in cellular metabolism and sive is placed on the cavity walls before condensation of the amalgamphospholipid destruction. It has oxidative actions that cause deactiva- alloy. The adhesive provides an immediate seal. When amalgam alloy istion of bacterial enzymes and causes lipid and fatty acid degradation used without an adhesive, it leaks initially, but “self seals” with time as(144). corrosion products form at the amalgam interface with tooth structure Several studies have shown that dentin that has been exposed to or other restorative materials (162). One strategy to use with amalgamsodium hypochlorite exhibits resin bond strengths that are significantly alloy, that offers theoretical advantages, is to seal only the chamber floorlower than untreated dentin (145–149). One study reported bond and orifices with adhesive resin to provide initial protection of the rootstrengths as low as 8.5 Mpa (147). Increased microleakage was also canal system from contamination. With time the amalgam restorationreported (150). This phenomenon probably occurs because sodium will corrode at the other interfacial areas and provide a seal that may behypochlorite is an oxidizing agent, which leaves behind an oxygen rich more durable than resin.layer on the dentin surface. Oxygen is another substance that inhibits the There is a theoretical advantage to using ad-mixture alloys overpolymerization of resins (151). Morris et al. showed that application of pure spherical alloys. Ad-mixture refers to a mixture of spherical and10% ascorbic acid or 10% sodium ascorbate, both of which are reduc- lathe cut particles. Ad-mixture alloys have slight setting expansion,ing agents, reversed the effects of sodium hypochlorite and restored which tends to reduce leakage (163), whereas spherical alloys shrinkbond strengths to normal levels. Lai et al. and Yiu et al. reported similar slightly while setting (163).results (149, 150). Because sodium hypochlorite is likely to remain theprimary irrigant used in endodontics for the near future, and because Composite Resinadhesive resin materials are used routinely in restoring endodontically Not surprisingly, composite resin is the most common choice fortreated teeth, this issue will have to be addressed. Future adhesive resin restoring access cavities in ceramic restorations (161). Composite canproducts for endodontic applications may contain a reducing agent to be bonded to tooth structure and most restorative materials, and can provide a good match of color and surface gloss. Bonded composite materials can also strengthen existing coronal or radicular tooth struc- ture, at least in the short term (164, 165). The limitations of composite resin as a restorative material are primarily related to polymerization shrinkage. Restorative resins are reported to exhibit shrinkage in the range of 2 to 6% during polymer- ization (43, 166). Less filler (such as found in “flowable” composites) results in more shrinkage (166, 167). Polymerization shrinkage causes stress on the adhesive bond that often results in gap formation (43). One study reported the percentage of dentinal gaps found in vivo was 14Figure 7. Example of the cleaning effect of sandblasting. Cleaning with alcohol to 54% of the total interface (168). Marginal deterioration of compositeand chloroform left a film on the dentin surface, shown in the first picture. Note restorations expedites the loss of dentin adhesion (169).how much cleaner the dentin appears in the second picture, after microabra- Composite restorative materials come in several forms: light-cure,sion (Courtesy of Dr. Fred Tsusui, Los Angeles). self- (chemical) cure or dual-cure. Light-cure materials consist of aJOE — Volume 31, Number 3, March 2005 Restoration of Access Cavities 157
  8. 8. ReviewFigure 8. (A) The access cavity is clean and ready to restore. (B) There was 10% hydrofluoric acid applied to the porcelain for 1 min and then rinsed thoroughly.(C) There was 37% phosphoric acid applied to the dentin and porcelain for 15 to 20 s. It demineralizes the dentin surface and cleans the porcelain. (D) The porcelainis thoroughly air dried and silane is applied and dried.single paste and polymerization is initiated with a curing light. Self-cure at the interface with cementum, which forms a weaker bond thanmaterials consist of two pastes that are mixed together to initiate poly- enamel (54). Because most curing lights can only effectively poly-merization. Dual-cure materials also consist of two pastes that are merize a thickness of 2 to 3 mm of composite material, cavities mustmixed together to initiate polymerization, but may also be light activated. be filled incrementally, a time consuming and tedious task. An ac-Dual-cure materials have the advantage of rapid polymerization in the areas cess cavity may require 3 to 5 increments. Because curing lights loseirradiated by the curing light, but chemical polymerization occurs in areas the intensity with distance, the light intensity may be greatly reduced atlight can not reach. the floor of the chamber when curing through an access opening in Light-cure materials polymerize in a matter of seconds and a crown. In addition, it may not be possible to irradiate all areasgenerally have the best physical properties. However, they have sev- inside an access cavity because of undercuts or difficulty in obtain-eral disadvantages. Because of the rapid polymerization, they tend to ing the proper angle with the light.stress the adhesive bond to tooth structure more than the slower Self-cure materials may be bulk filled because they do not requireself-cure composites (167). The stress is sometimes so great that penetration with a curing light. They polymerize more slowly than light-the restorative material debonds at the weakest interface (43, 170). cure materials, allowing the material to flow during polymerizationFor example, in class 5 composite restorations, they tend to debond contraction, and placing less stress on the adhesive bond (43, 167). The158 Schwartz and Fransman JOE — Volume 31, Number 3, March 2005
  9. 9. ReviewFigure 8 (continued). (E) A dentin primer is applied to all internal surfaces and air dried, and a dentin adhesive is applied to all internal surfaces and lightpolymerized. (F) A flowable composite is injected into the orifices and on the chamber floor and polymerized. This method minimizes voids between the restorativematerial and dentin. Because it is somewhat translucent, it makes location the canals easier if re-entry is necessary at a later time. (G) Incremental build-up, lightcomposite over dark. Increments should be only 2 to 3 mm in thickness to allow adequate polymerization. (H) Application of opaque composite. This is oftennecessary when restoring metal-ceramic crowns that tend to be quite opaque.same is true for dual-cure materials in the areas that are not irradiated debonding and microleakage (170). In a class 5 restoration, theby the curing light. ratio might be 1:1. In an access cavity, the C-factor might be 6:1 or The problem with polymerization shrinkage is amplified in even 10:1. In a root canal system obturated with a bonded resinaccess cavities because of a concept known as C-factor or configu- material, it might be 100:1 (43).ration factor (43, 167). C-factor refers to the ratio of bonded sur- An incremental filling technique with light-cure composite resinsfaces to free or unbonded surfaces. The higher the C-factor, the partially overcomes the problem of C-factor. Incremental filling is pos-greater the stress from polymerization shrinkage (43). Restorations sible because atmospheric oxygen prevents complete polymerization onwith C-factor higher than 3:1 are considered to be at risk for the external surface of the resin. This oily surface is referred to as theJOE — Volume 31, Number 3, March 2005 Restoration of Access Cavities 159
  10. 10. ReviewFigure 8 (continued). (I) Ocre colored modifiers are placed in the grooves. (J) Cusp inclines and triangular ridges are built up. (K) Brown modifiers are added tothe grooves and occlusion is checked. (L) Final result.“oxygen inhibited layer (151).” Because of the unpolymerized surface Glass Ionomer Cement and Resin Modified Glass Ionomer Materialslayer, additional increments may be added and polymerized and a Both types of glass ionomer materials may be bulk filled. Most of thestrong chemical bond is formed between increments (151). Incremen- RMGI materials are dual-cure. Traditional glass ionomer cements are self-tal filling allows complete polymerization of each increment, and less- cure and have very little polymerization shrinkage. Because resin is added toens the stress from polymerization shrinkage (171, 172) because the RMGI materials, they exhibit some polymerization shrinkage, although lessC-factor is more favorable for each increment than if the cavity was bulk than composite resins. Both types of glass ionomer materials are useful forfilled. Another strategy to lessen the effects of C-factor is to use slow bulk filling access cavities. Even though they bond to tooth structure, thesetting self-cured materials that flow during polymerization, thus reduc- bond strengths are too low to provide significant strengthening effect (174).ing stress (31, 167). If contamination occurs with blood or saliva during incrementalfilling, the bond between increments may be ruined. However, if the Material Incompatibilitiessurface is rinsed, dried and a dentin adhesive is applied, there is no loss The “self etching” adhesive systems have generally been shown toof bond strength (173). result in low bond strengths when used with self-cure composites and160 Schwartz and Fransman JOE — Volume 31, Number 3, March 2005
  11. 11. Reviewdual-cure composites that have not been light activated (126, 175– 8. Apply a dentin primer and adhesive to the internal walls and light178). This is in part because of residual acid on the dentin surface. cure.Self-cure composites contain tertiary amines in the catalyst that initiate 9. Fill the cavity incrementally with no increments greater than 3the polymerization reaction and have a high pH. Loss of bond strength mm.results because residual acid from the acidic primer inhibits the basic 10. Light cure each increment for 40 s (time depends on type of lightamines, resulting in incomplete polymerization at the interface between used).the adhesive and the restorative material (175, 176, 179, 180). Dual- 11. The restoration should be slightly overfilled so it can be finishedcure composites exhibit bond strengths comparable to light-cure com- back to the margins.posites in the areas that are effectively light-cured (177), because they 12. Contour and adjust the occlusion.are not dependent on the basic amines. One study reported lower bond 13. Finish and polish the restoration.strengths with the self-cure composites than light-cure composites with In many cases, it is desirable to bulk fill most of the cavity with a“etch and rinse,” single bottle (5th generation) adhesives as well (181). glass ionomer material or self-cure or dual-cure composite, then ve- The second problem with many of the “self etching” adhesive neer it with a light-cure composite material that is esthetic and willsystems is that they act as permeable membranes. This is a problem withstand occlusal function. This method is more efficient than using awhen they are used with restorative materials that polymerize slowly. A purely light-cure composite, but the esthetic result may not be as good.permeable adhesive layer allows penetration of moisture from the den- A simple method to restore access cavities in teeth with ceramictin to the interface with the restorative material, which is hydrophobic restorations: Glass ionomer and composite(122, 179). Moisture penetration can result in a phenomenon known in 1. Treat the dentin with a polyalkenoic acid for 30 s.polymer chemistry as “emulsion polymerization,” in which there is 2. Bulk fill with a dual-cure glass ionomer material to within 2 to 3poor adaptation between the adhesive and restorative material (122). mm of the cavo-surface margin and light cure.Moisture at the interface probably also contributes to the degradation of 3. Etch the ceramic material with 10% hydrofluoric acid, or otherthe bond over time (122). suitable etching gel for 1 min, depending on the product. 4. Rinse and dry. Clinical Strategies 5. Apply silane to the etched ceramic surface and air dry. Most strategies for restoring access cavities require several steps 6. Apply the dentin primer and adhesive to the glass ionomer ma-and at least two layers of restorative material. Many approaches utilize terial and etched ceramic and light adhesive system and two restorative materials. The exception is un- 7. Place the first increment of light-cure composite. The first in-bonded amalgam alloy. crement should include the longest vertical wall and taper to the base of the opposing vertical wall.Restoring Access Cavities with Tooth Colored Materials 8. Light cure for 40 s (time depends on type of light used). Light-cure composite can be used to fill the entire access cavity if 9. Fill the remaining space with the second increment and lightit is filled incrementally. This method will provide the strongest bond to cure. The restoration should be slightly overfilled so it can betooth structure (181) and is the preferred method when it is necessary finished back to the maximize the tooth strengthening effects of the restoration. When 10. Contour and adjust the occlusion.executed with skill and knowledge of the materials, excellent esthetic 11. Finish and polish the restoration.results are possible (Fig. 8). However, this is a slow, time consuming A Simple Procedure for Composite Resinmethod. High initial bond strengths are also obtained with dual-curecomposites that are placed incrementally and light polymerized (177). The procedures are similar to those described with glass ionomerThis method may be preferred to incremental fill with purely light-cured material, but a 4th generation dentin adhesive system is used on thematerials if there are concerns about light penetration to all areas of the dentin and a dual-cure composite is substituted for the glass ionomercavity. material. As discussed earlier, the 4th generation adhesive systems are pref- 1. Treat the dentin and enamel, if present, with 30 to 40% phos-erable for endodontic restorative applications with composite materi- phoric acid for 15 s.als. They tend to form the best bond to dentin, and have few compati- 2. Thoroughly rinse and dry the dentin then rewet with a moistbility problems with restorative resins. They are also effective despite the sponge.use of eugenol containing sealers or temporary materials. 3. Apply primer and adhesive, following the manufacturer’s in- A method to restore access cavities in teeth with ceramic restora- structions.tions: Light-cure composite 4. Bulk fill with a dual-cure or self-cure composite to within 2 to 3 1. Clean the internal surfaces with a brush or cotton pellet con- mm of the cavo-surface margin and light cure. taining a solvent such as alcohol. 5. Etch the ceramic material with 10% hydrofluoric acid, or other 2. Sandblast the cavity, metal and ceramic, or lightly refresh them suitable etching gel for 1 min. with a bur. 6. Rinse and dry. 3. Etch the ceramic with hydrofluoric acid or other appropriate 7. Apply silane to the etched ceramic surface and air dry. etchant. 8. Apply the dentin primer and adhesive to the etched ceramic and 4. Rinse and dry. light cure for 15 s. 5. Apply phosphoric acid to the inside of the access cavity if restor- 9. Place the first increment of light-cure composite. The first in- ing with composite. Etching with phosphoric acid adds no re- crement should include the longest vertical wall and taper to the tention to porcelain, but it cleans the porcelain and enhances base of the opposing vertical wall. the silane adaptation (182). 10. Light cure for 40 s. 6. Rinse and dry. 11. Fill the remaining space with the second increment and light 7. Apply silane agent to the porcelain and dry. cure.JOE — Volume 31, Number 3, March 2005 Restoration of Access Cavities 161
  12. 12. Review 12. Contour and adjust the occlusion. 15. Ricucci D, Grondahl K, Bergenholtz G. Periapical status of root-filled teeth exposed 13. Finish and polish the restoration. to the oral environment by loss of restoration or caries. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2000;90:354 –9. Dual-cure composites that are bulk filled develop relatively low 16. Ricucci D, Bergenholtz G. Bacterial status in root-filled teeth exposed to the oralbond strengths to dentin, comparable to glass ionomer materials. Resin environment by loss of restoration and fracture or caries: a histobacteriological study of treated cases. Int Endod J 2003;36:787– 802.adhesives lose bond strength with time and function, whereas glass 17. Heling I, Bialla-Shenkman S, Turetzky A, Horwitz J, Sela J. The outcome of teeth withionomer bond strengths are relatively stable. So there is little if any periapical periodontitis treated with nonsurgical endodontic treatment: a comput-benefit to the use of dual-cure composites over glass ionomer materials erized morphometric study. Quintessence Int 2001;32:397– 400.for bulk filling the cavity. 18. Malone KH 3rd, Donnelly JC. An in vitro evaluation of coronal microleakage in obturated root canals without coronal restorations. J Endod 1997;23:35– 8. 19. Heling I, Gorfil C, Slutzky H, Kopolovic K, Zalkind M, Slutzky-Goldberg I. Endodontic Conclusions failure caused by inadequate restorative procedures: review and treatment recom- 1. Prevent contamination of the root canal system. mendations. J Prosthet Dent 2002;87:674 – 8. 2. Restore access cavities immediately whenever possible. 20. Tewari S, Tewari S. Assessment of coronal microleakage in intermediately restored 3. Use bonded materials endodontic access cavities. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2002;93:716 –9. 4. The 4th generation (three step) resin adhesive systems are pre- 21. Naoum HJ, Chandler NP. Temporization for endodontics. Int Endod J 2002;35:964 – ferred because they provide a better bond than the adhesives that 78. require fewer steps. 22. Dillard CR, Barfield RD, Tilashalski KR, Chavers LS, Eleazer PD. Comparison of 5. The “etch and rinse” adhesives are preferred to “self etching” endodontist versus generalist regarding preference for postendodontic use of cot- adhesive systems if a eugenol containing sealer or temporary ton pellets in pulp chamber. J Endod 2002;28:656 –7. 23. Wolcott JF, Hicks ML, Himel VT. Evaluation of pigmented intra-orifice barriers in material was used. endodontically treated teeth. J Endod 1999;25:589 –92. 6. “Self etching” adhesives should not be used with self-cure or 24. Wolanek GA, Loushine RJ, Weller RN, Kimbrough WF, Volkmann KR. In vitro bac- dual-cure restorative composites. terial penetration of endodontically treated teeth coronally sealed with a dentin 7. When restoring access cavities, the best esthetics and highest bonding agent. J Endod 2001;27:354 –7. initial strength is obtained with an incremental fill technique with 25. Galvan RR Jr, West LA, Liewehr FR, Pashley DH. Coronal microleakage of five ma- terials used to create an intracoronal seal in endodontically treated teeth. J Endod composite resin. 2002;28:59 – 61. 8. A more efficient technique which provides acceptable esthetics is 26. Belli S, Zhang Y, Pereira PN, Ozer F, Pashley DH. Regional bond strengths of adhe- to bulk fill with a glass ionomer material to within 2 to 3 mm of the sive resins to pulp chamber dentin. J Endod 2001;27:527–32. cavo-surface margin, followed by two increments of light-cure 27. Belli S, Zhang Y, Pereira PN, Pashley DH. Adhesive sealing of the pulp chamber. composite. J Endod 2001;27:521– 6. 28. Pisano DM, DiFiore PM, McClanahan SB, Lautenschlager EP, Duncan JL. Intraorifice 9. If retention of a crown or bridge abutment is a concern after root sealing of gutta-percha obturated root canals to prevent coronal microleakage. canal treatment, post placement increases retention to greater J Endod 1998;24:659 – 62. than the original. 29. Mah T, Basrani B, Santos JM, et al. Periapical inflammation affecting coronally- inoculated dog teeth with root fillings augmented by white MTA orifice plugs. J Endod 1003;29:442– 6. References 30. Deveaux E, Hildelbert P, Neut C, Boniface B, Romond C. Bacterial microleakage of 1. Schwartz RS, Robbins JW. Post placement and restoration of endodontically treated Cavit, IRM, and TERM. Oral Surg Oral Med Oral Pathol 1992;74:634 – 43. teeth: a literature review. J Endod 2004;30:289 –301. 31. Barkhordar RA, Kempler D. Microleakage of endodontic access cavities restored 2. Siqueira JF Jr, Rocas IN, Favieri A, Abad EC, Castro AJ, Gahyva SM. Bacterial leakage with composites. J Calif Dent Assoc 1997;25:215– 8. in coronally unsealed root canals obturated with 3 different techniques. Oral Surg 32. Zaia AA, Nakagawa R, De Quadros I, et al. An in vitro evaluation of four materials as Oral Med Oral Pathol Oral Radiol Endod 2000;90:647–50. barriers to coronal microleakage in root-filled teeth. Int Endod J 2002;35:729 –34. 3. Siqueira JF Jr. Aetiology of root canal treatment failure and why well-treated teeth 33. Webber RT, del Rio CE, Brady JM, Segall RO. Sealing quality of a temporary filling can fail. Int Endod J 2001;34:1–10. material. Oral Surg Oral Med Oral Pathol 1978;46:123–30. 4. Kakehashi S, Stanley HR, Fitzgerald RJ. The effects of surgical exposures of dental 34. Beach CW, Calhoun JC, Bramwell JD, Hutter JW, Miller GA. Clinical evaluation of pulps in germ-free and conventional laboratory rats. Oral Surg Oral Med Oral Path bacterial leakage of endodontic temporary filling materials. 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Coronal microleakage of three temporary 28:12– 8. restorative materials: an in vitro study. J Endod 2004;30:582– 4. 12. Hommez GM, Coppens CR, De Moor RJ. Periapical health related to the quality of 41. Chandler NP, Heling I. Efficacy of three cavity liners in eliminating bacteria from coronal restorations and root Fillings. Int Endod J 200235:680 –9. infected dentinal tubules. Quintessence Int 1995;26:655–9. 13. Tronstad L, Asbjornsen K, Doving L, Pedersen I, Eriksen HM. Influence of coronal 42. Barthel CR, Strobach A, Briedigkeit H, Gobel UB, Roulet JF. Leakage in roots coro- restorations on the periapical health of endodontically treated teeth. Endod Dent nally sealed with different temporary fillings. J Endod 1999;25:731– 4. Traumatol 2000;16:218 –21. 43. Carvalho RM, Pereira JC, Yoshiyama M, Pashley DH. A review of polymerization 14. Iqbal MK, Johansson AA, Akeel RF, Bergenholtz A, Omar R. 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Durability of the resin bond strength to the alumina ceramic ence of cracks, caries and marginal breakdown. Aust Dent J 2004;49:33–9. Procera. Dent Mater 2004;20:498 –508. 48. Thomas CC, Land MF, Albin-Wilson SM, Stewart GP. Caries detection accuracy by 81. Saygili G, Sahmali S. Effect of ceramic surface treatment on the shear bond strengths multiple clinicians and techniques. Gen Dent 2000;48:334 – 8. of two resin luting agents to all-ceramic materials. J Oral Rehabil 2003;30:758 – 64. 49. McComb D. Caries-detector dyes– how accurate and useful are they? J Can Dent 82. Sadan A, Blatz MB, Soignet D. Influence of silanization on early bond strength to Assoc 2000;66:195– 8. sandblasted densely sintered alumina. Quintessence Int 2003;34:172– 6. 50. McMullen AF 3rd, Himel VT, Sarkar NK. An in vitro study of the effect endodontic 83. Blatz MB, Sadan A, Martin J, Lang B. In vitro evaluation of shear bond strengths of access preparation has upon the retention of porcelain fused to metal crowns of resin to densely-sintered high-purity zirconium-oxide ceramic after long-term stor- maxillary central incisors. J Endod 1989;15:154 – 6. age and thermal cycling. J Prosthet Dent 2004;91:356 – 62. 51. Yu YC, Abbott PV. The effect of endodontic access cavity preparation and subsequent 84. Barghi N. To silanate or not to silanate: making a clinical decision. Compend Contin restorative procedures on incisor crown retention. Aust Dent J 1994;39:247–51. Educ Dent 2000;21:659 – 62, 664. 52. Mulvay PG, Abbott PV. The effect of endodontic access cavity preparation and sub- 85. Shen C, Oh WS, Williams JR. Effect of post-silanization drying on the bond strength sequent restorative procedures on molar crown retention. Aust Dent J 1996;41: of composite to ceramic. J Prosthet Dent 2004;91:453– 8. 134 –9. 86. Eikenberg S, Shurtleff J. 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