Repair or replacement of defective direct resin-based composite restorations: contemporary teaching in U.S. and Canadian dental schools.

BACKGROUND: Opportunities exist to promote minimally invasive dentistry by repairing rather than replacing defective and failing direct resin-based composite restorations. The authors conducted a study to investigate the current teaching of such techniques in U.S. and Canadian dental schools. METHODS: In late 2010, the authors, with the assistance of the Consortium of Operative Dentistry Educators, invited 67 U.S. and Canadian dental schools to participate in an Internet-based survey. RESULTS: The response rate was 72 percent. Eighty-eight percent of the dental schools taught repair of defective direct resin-based composite restorations. Of these schools, 79 percent reported providing both didactic and clinical teaching. CONCLUSIONS: Although teaching repair of defective resin-based composite restorations was included in the didactic curricula of most schools, students in some schools did not gain experience in minimally invasive management of defective resin-based composite restorations by means of performing repair procedures. The American Dental Association's Code on Dental Procedures and Nomenclature does not have a procedure code for resin-based composite restoration repairs, which may limit patients' access to this dental treatment. CLINICAL IMPLICATIONS: Teaching dental students minimally invasive dentistry procedures, including restoration repair, extends the longevity of dental restorations and reduces detrimental effects on teeth induced by invasive procedures, thereby serving the interests of patients.

The effect of subject age on the microtensile bond strengths of a resin and a resin-modified glass ionomer adhesive to tooth structure.

In this study, the microtensile bond strengths of an etch-and-rinse resin adhesive to dentin and enamel and a resin-modified glass ionomer adhesive to dentin were determined on teeth known to have originated from subjects over 60 years of age. The same tests were repeated on teeth originating from young subjects. The resin adhesive was Prime & Bond NT (Caulk/Dentsply), while the resin-modified glass ionomer adhesive was Fuji Bond LC (GC America). Both were paired with the same hybrid resin composite, TPH3 (Caulk/Dentsply). Testing was performed after 48 hours using a "non-trimming" microtensile test at a crosshead speed of 0.6 mm/minute. No significant differences were observed between the young and aged teeth for any comparison (p > 0.05). SEM evaluation of the etched dentinal surfaces demonstrated less depth of decalcification in the intertubular areas of aged dentin, but there was no observable difference within the tubules of young and aged dentin.

Microtensile dentin and enamel bond strengths of recent self-etching resins.

In this study, the microtensile bond strengths of resin composites to dentin and enamel produced by recently introduced self-etching resins were determined. Included were two adhesives with self-etching primers, Clearfil SE (Kuraray) and Peak SE (Ultradent), four self-etching adhesives, Optibond All-In-One (Kerr), Clearfil S3 (Kuraray), Adper Prompt L-Pop (3M ESPE) and iBond (Heraeus Kulzer) and, as a positive control, PQ1 (Ultradent), an etch-and-rinse adhesive. Each product was evaluated using the same hybrid resin composite, Z250 (3M ESPE). Testing was performed after 48 hours using a "non-trimming" microtensile test at a crosshead speed of 0.6 mm/minute. Sample size was five teeth per group, with the value for each tooth calculated by averaging the bond strengths of seven beams derived from it. Mean values in MPa (SD) for dentin were: Clearfil SE 81.6 (3.5),a Peak SE 80.3 (9.9),a PQ1 73.4 (4.9),a,b Optibond All-In-One 64.4 (5.9),b Clearfil S3 62.5 (2.2),b,c iBond 51.0 (4.0)c and Prompt L-Pop 33.9 (6.4).d Mean values in MPa (SD) for enamel were: PQ1 55.6 (2.5),a Clearfil SE 54.1 (5.4),a Prompt L-Pop 54.0 (5.4),a Peak SE 51.8 (1.5),a,b Clearfil S3 44.3 (5.2),b,c Optibond All-In-One 40.1 (2.1)c,d and iBond 33.8 (3.3).d (Values for each substrate with the same letter were not significantly different, one-way ANOVA, Tukey-Kramer Multiple Comparison Test, p<0.05.) Compared to the positive control, PQ1, only adhesives with self-etching primers, Clearfil SE and Peak SE, were as effective in bonding to both enamel and dentin. With the exception of Prompt L-Pop, scanning electron micrographs of the etched enamel surface produced by self-etching products indicated far less surface topography than conventional etching, even for self-etching primer systems producing the same bond strengths as the etch-and-rinse adhesive.

The microtensile bond strength of self-etching adhesives to ground enamel.

It is uncertain whether single-phase self-etching adhesives form bonds to enamel as reliable as those of etch-and-rinse adhesives. This study compared the microtensile bond strengths to ground enamel of three self-etching adhesive systems, a self-etching primer system and an etchand-rinse adhesive system. Human enamel was ground flat with 320-grit silicone carbide paper. The self-etching adhesives iBond (Heraeus Kulzer), Prompt L-Pop (3M ESPE) and Xeno III (Caulk/Dentsply), the adhesive with a self-etching primer Clearfil SE Bond (Kuraray) and the etch-and-rinse adhesive Scotchbond Multipur-pose (3M/ESPE) were applied as directed, followed by a core of the same manufacturers' hybrid resin composite. A microtensile bond strength evaluation was performed after 48 hours of water storage, using untrimmed beams approximately 0.9 mm2 in cross-sectional area at a crosshead speed of 0.6 mm/minute. There were no pretest failures in any group, and failures were predominately adhesive or mixed. Adhesion to enamel of Clearfil SE was not significantly different from Scotchbond Multi-Purpose, while the three self-etching adhesive systems demonstrated significantly lower bond strengths (One-way ANOVA, Tukey-Kramer Multiple-Comparison Test, p < 0.00001).

Microleakage of Class V resin composites placed using self-etching resins: effect of prior enamel etching.

OBJECTIVE: The purpose of this study was to compare the seal along dentin and enamel margins produced by 3 self-etching resin bonding systems to that of an etch-and-rinse adhesive system. Potential improvement in adaptation along enamel margins through the experimental use of conventional enamel etching prior to application of the self-etching adhesives was also evaluated. METHOD AND MATERIALS: Class V resin composite restorations were placed in prepared cavities in extracted third molars using 3 self-etching dentin adhesive systems: Adper Prompt L-Pop (3M Espe), iBond GI (Heraeus Kulzer), and Tyrian SPE (Bisco), and an etch-and rinse adhesive, Adper ScotchBond Multi-Purpose (3M Espe). A group of teeth also underwent conventional enamel etching prior to use of the self-etching products. The restored teeth were thermocycled, subjected to a dye challenge, and sectioned. The sections were scored using an ordinal leakage scale (n = 20). Ranked data were analyzed using a 2-way analysis of variance and Tukey multiple comparison. RESULTS: When used as directed, there were no significant differences along dentin margins for any of the adhesives, but Adper Prompt and iBond demonstrated significantly greater leakage than the etch-and-rinse product along enamel margins. The incidence of enamel margin leakage decreased significantly for the same 2 products when enamel etching preceded use of the resin. Enamel etching increased the leakage along dentin margins for all 3 self-etching products, but not significantly. CONCLUSION: Considerable improvement of all classes of dentin-adhesive resin systems is still needed. Practitioners should await further clinical trials before adopting use of self-etching resins, especially for large occlusal restorations.

Microtensile dentin bond strength of self-etching resins: effect of a hydrophobic layer.

In this study, the microtensile bond strength of resin composites to dentin was determined when hydrophilic self-etching resins were used with and without an additional layer of a more hydrophobic adhesive. Included were three single-step self-etching adhesives, Adper Prompt L-Pop (3M ESPE), iBond GI (Heraeus Kulzer, Inc) and Xeno III (Caulk/Dentsply), and as a negative control, UniFil Bond (GC America), a self-etching primer with a separate adhesive. Each product was evaluated using a hybrid resin composite from its respective manufacturer, and each was used as directed and then used with an added layer of a more hydrophobic resin from its respective manufacturer. Testing was performed after 72 hours using a "non-trimming" microtensile test at a crosshead speed of 0.6 mm/minute. When the products were used according to manufacturers' directions, iBond had a significantly higher bond strength to dentin than the other three products (p<0.001), which were not significantly different from each other. For the three self-etching adhesive systems, the addition of a layer of a more hydrophobic resin produced significantly higher bond strengths to dentin (p<0.001), while no significant effect was found for the self-etching primer (p=0.40). A significant interaction was found between the variables product and adhesive treatment. The TEM evaluation of Prompt L-Pop and iBond demonstrated reduced nanoleakage with the additional resin layer.

Microleakage of Class V resin composite restorations placed with self-etching adhesives.

STATEMENT OF PROBLEM: Although they are widely available, there is insufficient information about the capability of self-etching adhesives in sealing the margins of resin composite restorations. PURPOSE: The purpose of this study was to compare the in vitro microleakage of Class V resin composite restorations placed using a strong pH self-etching adhesive, an intermediate pH self-etching adhesive, and an adhesive with a separate etchant and primer. MATERIAL AND METHODS: Class V resin composite restorations (n = 8) were placed in prepared cavities in extracted human third molars using 2 self-etching dentin adhesives, Prompt L-Pop (Strong pH) or One-Up Bond F (Intermediate pH), and an adhesive with a separate etchant and primer, ScotchBond Multi-Purpose. The restored teeth received 1000 thermal cycles between 5 degrees C and 55 degrees C water baths with a 1-minute dwell time and were subsequently subjected to a methylene blue dye challenge and sectioned. The sectioned specimens were scored as demonstrating none, slight, or severe leakage (n=16). Ranked data were analyzed using a 1-way analysis of variance at a 5% confidence level. RESULTS: The only leakage observed was along gingival margins, with an incidence of 31% for Prompt L-Pop and One-Up Bond F, and 50% for ScotchBond Multi-Purpose. CONCLUSION: No significant differences in marginal leakage were found among the adhesives tested.

The effect of elevated temperatures on the dentin adhesion of resin composites.

Although resin composite restorations may undergo relatively extreme temperature changes in the oral cavity, little is known about the effects of temperature on their adhesion to tooth structure. This study evaluated the effect of temperature on shear bond strength to dentin of three commercial resin dentin adhesives through testing of matured specimens over the 20 degrees to 55 degrees C temperature range. A significant difference (p < 0.05) was observed between 20 degrees C and 55 degrees C for all the materials, and for one of the materials, a significant difference was also observed between 20 degrees C and 37 degrees C.