Universal Adhesives Benefit from an Extra Hydrophobic Adhesive Layer When Light Cured Beforehand.

PURPOSE: To measure microtensile bond strength (µTBS) of universal adhesives immediately and after 6-month aging, with or without an additional adhesive layer applied on a separately light-cured or non-light-cured universal adhesive. MATERIALS AND METHODS: Eighty human third molars were randomly assigned to 8 experimental groups. The universal adhesives Clearfil Universal Bond (Kuraray Noritake) and Single Bond Universal (3M Oral Care) were used in self-etch mode (following the manufacturer's directions), and either light cured or not before application of an extra hydrophobic adhesive layer (Clearfil SE Bond bond, Kuraray Noritake). The two-step self-etch adhesives Clearfil SE Bond (Kuraray Noritake) and OptiBond XTR (Kerr) were used as references. After composite buildups were bonded to mid-coronal occlusal dentin surfaces, the specimens were stored in water (37°C/24 h) and sectioned into microspecimens (0.96 ± 0.04 mm2). Half of the specimens were immediately subjected to µTBS testing (1.0 mm/min), while the other half was stored in water (37°C) for 6 months prior to testing. Failure analysis was performed using stereomicroscopy and SEM. Data were analyzed with two-way repeated measures ANOVA, Tukey's and paired t-tests (p = 0.05). RESULTS: The immediate µTBS was similar for the universal adhesives when applied following the different application strategies (p > 0.05). Application of an extra layer of hydrophobic adhesive improved the aged µTBS of the universal adhesives, which was statistically significant when the universal adhesives were first light cured (p < 0.05). The reference adhesives Clearfil SE Bond and OptiBond XTR exhibited a significantly higher immediate and aged µTBS to dentin than did the universal adhesives (p < 0.05). CONCLUSION: The bond durability of universal adhesives, applied in self-etch mode, was found to benefit from the application of an extra hydrophobic adhesive layer when the universal adhesives were first light cured.

Effect of tooth discolouration severity on the efficacy and colour stability of two different trayless at-home bleaching systems.

Background. The use of trayless at-home bleaching agents in darker teeth is raising some concerns due to their unknown efficacy. The purpose of this in vitro study was to evaluate the effect of tooth discolouration severity on the efficacy and colour stability of two different trayless at-home bleaching systems. Methods. Ninety enamel-dentin samples were divided into two groups: lighter tand darker teeth. The teeth in each group were further divided into three groups (n=15): (1) tray-based system with 10% carbamide peroxide (Opalescence Oh) (control group); (2) a tray applied whitening membrane with 10% hydrogen peroxide (Treswhite Supreme); and (3) a whitening pen with 22% carbamide peroxide (Hollywood Smiles). After bleaching, the teeth were stained for 9 days using red wine. Colour readings before bleaching treatment were determined using a dental spectrophotometer and were repeated 24 h after bleaching treatment and 24 h after staining process. Analysis of variance, Bonferroni and Dunnett C tests were used at 5% significance level. Results. No differences were observed between the bleaching efficacy of Treswhite Supreme and Opalescence Oh in the lighter teeth, while Opalescence Oh had the best bleaching efficacy in the darker teeth (p<0.05). Hollywood Smiles had the worst bleaching efficay but the best color stability in both lighter and darker teeth (p<0.05). No differences were observed between the color stability values of Treswhite Supreme and Opalescence Oh. Conclusion. This study suggested that both the tooth discolouration severity and the type of trayless system used affected the bleaching efficacy, whereas only the type of trayless system affected the color stability.

Effect of resin infiltration and microabrasion on the microhardness, surface roughness and morphology of incipient carious lesions.

OBJECTIVE: The effects of resin infiltration and microabrasion on incipient carious lesions by surface microhardness, roughness and morphological assessments, and resistance to further acid attack of treated lesions were evaluated. MATERIAL AND METHODS: Eighty artificially-induced incipient lesions were randomly divided into five groups (n = 16): resin infiltration with an adhesive resin (Excite F, Ivoclar Vivadent, Schaan, Liechtenstein), resin infiltration with a resin infiltrant (Icon, DMG, Hamburg, Germany), microabrasion without polishing (Opalustre, Ultradent, South Jordan, UT, USA), microabrasion with polishing (Opalustre, Ultradent, Diamond Excel, FGM, Joinville, SC, Brazil), and distilled water (control group). All specimens were exposed to demineralization for another 10 d. Microhardness, roughness and morphological assessments were done at baseline, following initial demineralization, treatment and further demineralization. Data were analysed by the Kruskal-Wallis, Friedman's and Bonferroni tests (p < .05). RESULTS: Enamel lesions treated with resin infiltrant and microabrasion demonstrated similar hardness values, with a nonsignificant difference compared with sound enamel. Resin infiltration demonstrated lower roughness values than those of microabrasion, and the values did not reach the values of sound enamel. Further demineralization for 10 d did not affect the hardness but increased the roughness of infiltrated and microabraded enamel surfaces. Polishing did not influence the roughness of microabraded enamel surfaces. After resin infiltration, porosities on enamel were sealed completely. The surface structure was similar to that of the enamel conditioning pattern for microabraded enamel lesions. CONCLUSIONS: Within the limitations of this study, the icon infiltration and microabrasion technique appeared to be effective for improving microhardness. Icon appeared to provide reduced roughness, although not equal to sound enamel. Further research is needed to elucidate their clinical relevance.

Bond strength and cement-tooth interfacial characterization of self-adhesive composite cements.

PURPOSE: (1) To determine the microtensile bond strength (µTBS) of self-adhesive (SA) composite cements to unetched/etched enamel and dentin, and (2) to characterize the cements' interaction with tooth tissue. METHODS: 51 composite blocks were bonded to smear layer-covered enamel and dentin (three teeth per group). Four SA composite cements (Clearfil SA, G-CEM, RelyX Unicem, SmartCem2), and three multi-step composite cements, two used following an etch-and-rinse (E&R) approach (RelyX ARC, Variolink II 'E&R') and one used following a self-etch (SE) approach (Variolink II ' SE') were investigated. The cement-tooth specimens were perpendicularly sectioned into micro-specimens (1.0 × 1.0 mm) in order to measure the µTBS. The data were statistically analyzed by ANOVA followed by Tukey HSD (P< 0.05). 24 additional specimens (four teeth per group) were prepared for interfacial characterization using SEM. RESULTS: The tested SA cements bonded equally well to enamel and dentin. Etching of enamel improved their bonding effectiveness, which however remained inferior to that of both E&R cements. SEM revealed a very similar interfacial ultrastructure at smear layer-covered enamel and dentin for the SA cements, exhibiting very superficial interaction at enamel and absence of a clearly detectable hybrid layer and resin tags in the dentin tubules. When the SA composite cements were applied to dentin free of a smear layer, regular and long resin tags were formed. CLINICAL SIGNIFICANCE: No significant differences in bonding effectiveness were recorded for the self-adhesive composite cements when bonded to unetched/etched enamel and to dentin. Multi-step etch-and-rinse composite cements showed a better bonding effectiveness to enamel, although this could be approximated by the self-adhesive composite cements when enamel was acid-etched beforehand. On dentin, however, the bond strength of the etch-and-rinse composite cement RelyX ARC was superior.

Microindentation hardness and calcium/phosphorus ratio of dentin following excavation of dental caries lesions with different techniques.

BACKGROUND: The aim of this in vitro study was to evaluate the microindentation hardness and chemical composition of residual dentin left at the cavity bottom following removal of carious dentin using the Carisolv chemomechanical and Er:YAG laser caries excavation methods in comparison with the conventional tungsten-carbide bur excavation. METHODS: Sixty-nine extracted permanent teeth with occlusal dentin caries were assigned into three groups according to caries removal technique. Carious dentin excavation was guided by tactile method and a caries-staining dye. In stereomicroscope images (100×) of the samples, the presence or absence of residual caries was defined. The Knoop hardness value of the cavity floor was determined and atomic analysis of treated cavities was performed by energy dispersive X-ray spectroscopy. RESULTS: The Knoop hardness value of residual dentin left at the cavity bottom was lower (One-way ANOVA, Dunnett-C, p < 0.05) and the percentage of samples with remaining carious dentin was higher after Carisolv excavation than those obtained after conventional and laser excavations (Kruskal-Wallis, Mann-Whitney U, p < 0.05). No significant differences were found between the quantities of calcium content (Ca wt%), phosphorus content (P wt%) and calcium/phosphorus ratio of the cavities treated by three techniques (Kruskal-Wallis, Mann-Whitney U, p > 0.05). CONCLUSION: The results indicated that Er:YAG laser was more comparable to conventional bur excavation than chemomechanical method in the efficacy of caries removal with regard to microindentation hardness of remaining dentin and both Carisolv gel and Er:YAG laser did not alter chemical composition of residual dentin in the treated cavities.

Radiopacity evaluation of contemporary resin composites by digitization of images.

OBJECTIVE: The aim of this study was to evaluate the radiopacity of different composite resins and compare the values to those of human enamel and dentine. MATERIALS AND METHODS: Five specimens of each material with thicknesses of 2 mm were prepared and radiographed alongside aluminum step wedge and human enamel and dentin. Three occlusal radiographs for each material were taken and digitized using a desktop scanner. Mean gray values of the test materials were measured using Image J software. Then a conversion was performed according to establish the radiopacity of the test materials, in millimeters of equivalent Al. Data were analyzed using one-way analysis of variance and Duncan multiple range tests (P < 0.05). RESULTS: The radiopacity values varied among the restorative materials (P < 0.05). The radiopacity values of the materials tested were, in decreasing order: Enamel Plus HRI > Z250 > Filtek Ultimate ≥ Z550 > Nexcomp ≥ Nanoceram Bright > enamel ≥ Estelite Sigma Quick > Clearfil Majesty Esthetic ≥ Reflexions XLS ≥ Aelite LS Posterior ≥ dentin ≥ 2 mm Al. CONCLUSION: All resin composite materials investigated in this study presented different radiopacity values. However, all materials had radiopacity values greater than dentin and had sufficient radiopacity to meet International Organization for Standardization 4049 standard.

Five-year clinical performance of a HEMA-free one-step self-etch adhesive in noncarious cervical lesions.

OBJECTIVES: The objective of this randomized controlled trial was to evaluate the clinical performance of a 2-hydroxyethyl methacrylate (HEMA)-free one-step adhesive. MATERIALS AND METHODS: Two hundred sixty-seven cervical lesions in 52 patients were restored with the composite Gradia Direct (GC), bonded with either the one-step self-etch adhesive G-Bond (GC) or the three-step etch-and-rinse adhesive Optibond FL (Kerr) in a random order. The restorations were evaluated for retention, marginal integrity, marginal discoloration, and caries occurrence after 5 years. Specific statistics were used to account for the clustered data (multiple restorations per patient). RESULTS: The clinical success rate for G-Bond (87.4 %) was not significantly different from that of Optibond FL (90.9 %). Both adhesives showed progressive marginal deterioration, but G-Bond exhibited more small enamel defects and marginal discoloration, and unlike previous recalls, several restorations failed because of deep microleakage. Large sclerotic lesions were a significant risk factor for retention loss with G-Bond. Irrespective of the adhesive, almost all restorations with retention loss were located in the lower jaw. CONCLUSION: After 5 years of clinical service, restorations bonded with the HEMA-free one-step adhesive did not need repair or replacement more often than those with the three-step etch-and-rinse adhesive, and both adhesives had a high retention rate (>90 %). There were indications that G-Bond did not (self-)etch enough in some clinical situations, as G-Bond exhibited more incisal defects and marginal discolorations, and sclerotic lesions were at higher risk of retention loss. CLINICAL RELEVANCE: The clinical performance of the HEMA-free one-step adhesive was clinically acceptable after 5 years.

Clinical effectiveness of a one-step self-etch adhesive in non-carious cervical lesions at 2 years.

A 2-year randomized, controlled prospective study evaluated the clinical effectiveness of a one-step self-etch adhesive and a "gold-standard" three-step etch-and-rinse adhesive in non-carious Class-V lesions. The null hypothesis tested was that the one-step self-etch adhesive does perform clinically equally well as the three-step etch-and-rinse adhesive. A total of 161 lesions in 26 patients were restored with Clearfil AP-X (Kuraray). The restorations were bonded either with the "all-in-one" adhesive Clearfil S3 Bond (Kuraray) or with the three-step etch-and-rinse adhesive Optibond FL (Kerr). The restorations were evaluated at baseline and after 6 months, 1 and 2 years, regarding their retention, marginal adapation, marginal discoloration, caries occurrence, preservation of tooth vitality and post-operative sensivity. Retention loss, severe marginal defects and/or discoloration that needed intervention (repair or replacement) and the occurrence of caries were considered as clinical failures. The recall rate at 2 years was 93.8%. Only one Clearfil S3 Bond restoration was lost at the 2-year recall. All other restorations were clinically acceptable. The number of restorations with defect-free margins decreased severely during the 2-year study period (to 6.7% and 25.3% for Clearfil S3 Bond and Optibond FL, respectively). The Clearfil S3 Bond restorations presented significantly more small marginal defects at the enamel side than the Optibond FL restorations (Clearfil S3 Bond: 93.3%; Optibond FL: 73.3%; p = 0.000). Superficial marginal discoloration increased in both groups (to 53.3% and 36% for Clearfil S3 Bond and Optibond FL, respectively) and was also more pronounced in the Clearfil S3 Bond group (p = 0.007). After 2 years, the simplified one-step self-etch adhesive Clearfil S3 Bond and the three-step etch-and-rinse adhesive Optibond FL were clinically equally successful, even though both adhesives were characterized by progressive degradation in marginal integrity. Clearfil S3 Bond exhibited more small enamel marginal defects and superficial marginal discolorations.

Clinical performance of a two-step self-etch adhesive with additional enamel etching in Class III cavities.

OBJECTIVE: This study evaluated the effect of additional enamel etching on the clinical performance of Class III composite restorations bonded with a mild two-step self-etch adhesive system in a three-year evaluation of clinical service. METHODS: Using a paired-tooth study design, 38 patients received at least one pair of restorations. In each paired cavity, a mild two-step self-etch adhesive (Clearfil SE Bond) was used, either with (C-SE etch) or without additional enamel etching, using phosphoric acid (C-SE non-etch). Clearfil AP-X was used as the restorative material for all restorations. Evaluation of the restorations was performed at baseline and after six months, one year, two years and three years of clinical service in terms of retention, marginal discoloration, marginal adaptation, postoperative sensitivity and secondary caries using the modified Ryge criteria. RESULTS: A retention rate of 100% both for the C-SE non-etch and C-SE etch groups was noted. Significant differences were observed between the groups regarding the marginal discoloration (p = 0.001) and marginal adaptation (p = 0.002) at three years. C-SE non-etch restorations revealed more small marginal defects and superficial marginal discoloration than the C-SE etch group. CONCLUSION: Although the clinical performance of the mild two-step self-etch adhesive in Class III cavities was found acceptable after three years, additional etching of the enamel margins improved the marginal quality of this adhesive by preventing small marginal defects and superficial marginal discolorations.

Clinical evaluation of a two-step etch&rinse and a two-step self-etch adhesive system in Class II restorations: two-year results.

OBJECTIVE: This study evaluated the clinical performance of a two-step etch&rinse and a two-step self-etch adhesive system in Class II restorations after two years of clinical service. METHODS: Thirty-three patients with primary caries or insufficient restorations were enrolled in the study. A total of 87 Class II cavities were restored, 44 using a two-step etch&rinse adhesive system (Single Bond, 3M ESPE) and 43 cavities using a two-step self-etch adhesive (Clearfil SE Bond, Kuraray). Filtek Z250 (3M ESPE) was used as a restorative material for all the restorations. The restorations were evaluated at baseline, six months, and one and two years after placement for retention, marginal discoloration, marginal adaptation, postoperative sensitivity, secondary caries, color match and anatomical form, according to the modified Ryge criteria. RESULTS: At two years, the retention rates for Single Bond and Clearfil SE Bond were 94% and 100%, respectively, (p = 0.493). No significant differences were found between both groups for the other parameters evaluated. CONCLUSION: Both of the adhesive systems that were tested demonstrated similar clinical performance at the end of this two-year clinical trial.

Influence of Er,Cr:YSGG laser treatment on microtensile bond strength of adhesives to enamel.

The current trend towards minimum-intervention dentistry has introduced laser technology as an alternative technique for cavity preparation. This study assessed the null hypothesis that enamel prepared either by Er,Cr:YSGG laser or conventional diamond bur is equally receptive to adhesive procedures. The buccal and lingual surfaces of 35 sound human molars were prepared with Er,Cr:YSGG laser or a medium-grit diamond bur. One etch&rinse (OptiBond FL) and three self-etch adhesives (Adper Prompt L-Pop, Clearfil SE Bond and Clearfil S3 Bond) were applied on laser-irradiated and bur-cut enamel, followed by the application of a 5-6 mm build-up of Z100. The micro-tensile bond strength (microTBS) was determined after 24 hours of storage in water at 37 degrees C. Prepared enamel surfaces and failure patterns were evaluated using a stereomicroscope and a field-emission-gun scanning electron microscope (Feg-SEM). The pTBS to laser-irradiated enamel was significantly lower than to bur-cut enamel (p<0.05), with the exception of Clearfil S3 Bond, which bonded equally effectively to both substrates. The latter presented the highest microTBS on laser-irradiated enamel, though it was not statistically different from the microTBS of OptiBond FL. SEM analysis revealed significant morphological alterations of the laser-irradiated enamel surface, such as areas of melted and recrystalized hydroxyapatite and deep extensive micro-cracks. In conclusion, the bonding effectiveness of adhesives to laser-irradiated enamel depends not only on the structural substrate alterations induced by the laser, but also on the characteristics of the adhesive employed.

Influence of Er,Cr:YSGG laser treatment on the microtensile bond strength of adhesives to dentin.

PURPOSE: In light of the concept of minimally invasive dentistry, erbium lasers have been considered as an alternative technique to the use of diamond burs for cavity preparation. The purpose of this study was to assess the bonding effectiveness of adhesives to Er,Cr:YSGG laser-irradiated dentin using irradiation settings specific for cavity preparation. MATERIALS AND METHODS: Fifty-four midcoronal dentin surfaces, obtained from sound human molars, were irradiated with an Er,Cr:YSGG laser or prepared with a diamond bur using a high-speed turbine. One etch-and-rinse (Optibond FL/Kerr) and three self-etching adhesives (Adper Prompt L-Pop/3M ESPE, Clearfil SE Bond/Kuraray, and Clearfil S3 Bond/Kuraray) were used to bond the composite to dentin. The microtensile bond strength (microTBS) was determined after 24 h of storage in water at 37 degrees C. The Kruskal-Wallis test was used to determine pairwise statistical differences (p < 0.05). Prepared dentin surfaces, adhesive interfaces, and failure patterns were analyzed using a stereomicroscope and Field-emission gun Scanning Electron Microscopy (Feg-SEM). RESULTS: Significantly lower microTBS was observed to laser-irradiated than to bur-cut dentin (p < 0.05), irrespective of the adhesive employed. Feg-SEM photomicrographs of lased dentin revealed an imbricate patterned substrate and the presence of microcracks at the dentin surface. CONCLUSION: Morphological alterations produced by Er,Cr:YSGG laser-irradiation adversely influence the bonding effectiveness of adhesives to dentin.

Bond strength of self-etch adhesives to dentin prepared with three different diamond burs.

OBJECTIVES: To evaluate the micro-tensile bond strength (mu TBS) of a control etch-and-rinse and three self-etch (strong, mild, ultra-mild) adhesive systems to dentin prepared with three different grit size of diamond burs. METHODS: Dentin surfaces were created from mid-coronal sound dentin in extracted, human third molars. The teeth were ground with high-speed medium grit (100 microm), fine grit (30 microm), or extra-fine grit (15 microm) diamond bur. Resin composite (Z100) was bonded to the surfaces using Optibond FL, Adper Prompt L-Pop, Clearfil SE Bond, or Clearfil S3 Bond. Rectangular micro-specimens were prepared using the slow-speed diamond saw and tested in tensile to determine the mu TBS. Failure analysis was performed using a stereo-microscope and Fe-SEM. Data were analyzed by two-way analysis of variance and Tukey's HSD test (p<0.05). RESULTS: The etch-and-rinse adhesive yielded high micro-tensile values (58-69 MPa), irrespective of the diamond burs used. The bond strength values were comparable for Adper Prompt L-Pop and Clearfil SE Bond irrespective of the burs used. The mu TBS values were significantly higher as the particle size of diamond burs is smaller for Clearfil S3 Bond. Most failures were recorded as interfacial failure when the fine and extra-fine diamond burs were used. SIGNIFICANCE: Overall, different grit-sized diamond burs did not affect the mechanical properties of the interface, except for the ultra-mild one step self-etch adhesive. This adhesive performed significantly better when a smaller grit size was used to prepare dentin surface.

Influence of dentin cavity surface finishing on micro-tensile bond strength of adhesives.

UNLABELLED: The current trend toward minimal-invasive dentistry has introduced innovative techniques for cavity preparation. Chemical vapor deposition (CVD) and laser-irradiation technology have been employed as an alternative to the common use of regular burs in high-speed turbines. OBJECTIVES: The purpose of this study was to assess the influence of alternative techniques for cavity preparation on the bonding effectiveness of different adhesives to dentin, and to evaluate the morphological characteristics of dentin prepared with those techniques. METHODS: One etch&rinse adhesive (OptiBond FL, Kerr) and three self-etch systems (Adper Prompt L-Pop, 3M ESPE; Clearfil SE Bond, Kuraray; Clearfil S3 Bond, Kuraray) were applied on dentin prepared with a regular bur in a turbine, with a CVD bur in a turbine, with a CVD tip in ultrasound and with an Er,Cr:YSGG laser. The micro-tensile bond strength (microTBS) was determined after storage in water for 24h at 37 degrees C, and morphological evaluation was performed by means of field-emission-gun scanning electron microscopy (Feg-SEM). RESULTS: Feg-SEM evaluation revealed different morphological features on the dentin surface after the usage of both the conventional and alternative techniques for cavity preparation, more specifically regarding smear-layer thickness and surface roughness. CVD bur-cut, CVD ultra-sonoabraded and laser-irradiated dentin resulted in lower microTBSs than conventionally bur-cut dentin, irrespective of the adhesive employed. SIGNIFICANCE: The techniques, such as CVD diamond-bur cutting, CVD diamond ultra-sonoabrasion and laser-irradiation, used for cavity preparation may affect the bonding effectiveness of adhesives to dentin, irrespective of their acidity or approach.

Comparison of conventional and digital radiography for radiometric differentiation of dental cements.

OBJECTIVE: To test the efficacy of conventional radiometry with indirect digital image analysis in the assessment of the relative radiopacity of dental cements used as liners or bases compared to human enamel and dentin. METHOD AND MATERIALS: Disks of 15 different dental cements, 5 mm in diameter and 2 mm thick, were exposed to radiation together with 2-mm-thick disks of enamel and dentin and an aluminum step wedge. Density was evaluated by digital transmission densitometry and with the histogram function of an image analysis program following digitization of the radiographs with a flatbed scanner. RESULTS: A higher number of dental cements were discriminated from both dentin and enamel with conventional radiographic densitometer. All the cements examined, except Ionoseal (Voco) and Ionobond (Voco), were more radiopaque than dentin. With both methods, Chelon-Silver (3M ESPE) had the highest radiopacity and glass-ionomer cements the lowest. CONCLUSION: Radiodensity of dental cements can be differentiated with a high probability with the conventional radiometric method.

Bonding to ground versus unground enamel in fluorosed teeth.

OBJECTIVES: To determine the effect of grinding on the bonding effectiveness of a self-etch and an etch-and-rinse adhesive to fluorosed enamel. METHODS: The teeth were classified using the Thylstrup and Fejerskov index (TFI). Fluorosed teeth (TFI=5) obtained from Isparta (Turkey) and control teeth (TFI=0) obtained from Leuven (Belgium) were used. Using a depth-marking diamond bur, 0.3mm of enamel was removed from mid-buccal and mid-palatal/lingual surfaces of the teeth, whereas the area adjacent to the ground area was left unprepared. A two-step self-etch (Clearfil Protect Bond, Kuraray) and a three-step etch-and-rinse adhesive (Optibond FL, Kerr) were used to bond the resin composite to the ground and unground enamel. Rectangular micro-specimens were prepared using the slow-speed diamond saw and tested in tensile to determine the micro-tensile bond strength (microTBS). RESULTS: The microTBS to unground fluorosed enamel was significantly lower than to ground fluorosed enamel for Clearfil Protect Bond (15.8+/-15.2 and 45.0+/-12.4MPa, p<0.0001) and for Optibond FL (35.5+/-21.4 and 50.5+/-12.3MPa, p<0.05), respectively. In control teeth, Clearfil Protect Bond bonded better to ground enamel (p<0.01), whereas OptiBond FL exhibited a similar bonding effectiveness to ground and unground enamel (p=0.0634). SIGNIFICANCE: Preparation of enamel improved the resin-enamel bond strength in fluorosed teeth. The bonding effectiveness to unground enamel was lower in fluorosed teeth than in control teeth for the self-etch adhesive tested.

NaOCl degradation of a HEMA-free all-in-one adhesive bonded to enamel and dentin following two air-blowing techniques.

OBJECTIVE: Phase-separation within HEMA-free all-in-one dental adhesives may result in the entrapment of droplets within the adhesive resin. Strongly air-blowing prior to polymerization, can remove most of these droplets. The objective of this study was to evaluate the effect these droplets may have on the resistance of the adhesive-tooth interface to NaOCl degradation. METHODS: The micro-tensile bond strength (microTBS) to enamel and dentin was determined when a HEMA-free all-in-one adhesive was applied either following a mild or strong air-blowing technique. The bonds were also exposed to an aqueous sodium hypochlorite (NaOCl) solution for 1h, following a recently introduced methodology to mimic in vivo bond degradation. RESULTS: This study revealed that strong air-blowing of the adhesive only resulted in a significantly higher micro-tensile bond strength (microTBS) to dentin, but not to enamel. Likewise, NaOCl only reduced the microTBS to dentin for both the mild and strong air-blowing technique, but again not the microTBS to enamel. Failure analysis by SEM clearly revealed that strong air-blowing is less effective in droplet removal when the adhesive was applied in small and narrow class-I cavities, as compared to when it was applied to flat surfaces. CONCLUSIONS: NaOCl did preferentially dissolve the hybrid layer at dentin, and more for the mild than for the strong air-blowing technique. A strong air-blowing procedure resulted in a more NaOCl-resistant hybrid layer, so that it can be concluded that a HEMA-free one-step adhesive definitely benefits from a strong air-blowing technique.

Examiner agreement in the replacement decision of Class I amalgam restorations.

The aim of this study was to investigate interexaminer and intraexaminer agreement in the replacement decision for Class I amalgam restorations. Three examiners evaluated the restorations clinically and with bitewing radiographs. One hundred and twelve restorations were evaluated for secondary caries, body fracture, deficient anatomic form (contour), ditched margins, and marginal overhangs. After one month, the assessments were repeated by the same examiners under the same conditions. Cohen's Kappa analysis was used to analyze the data. The number of replacement decisions varied from 12 to 27 and from 6 to 14 at the first and second evaluations, respectively. The Kappa statistics indicated "moderate" to "substantial" consistency for interexaminer and intraexaminer agreement in the replacement decisions based on clinical and radiographical examinations. Restorations with deficient anatomic form and marginal overhangs presented the most frequent diagnostic difficulties and lead to disagreement among examiners. The most frequently mentioned reasons for replacement were the restorations had ditched margins at both clinical evaluation periods and secondary caries was detected during radiographical evaluations. In the absence of agreement among examiners, clinical and radiographic guidelines are necessary for replacing Class I amalgam restorations.

Effect of fluorosis on dentine shear bond strength of a self-etching bonding system.

The purpose of this study was to investigate the effect of dental fluorosis on shear bond strength of a composite material to dentine. Forty human premolar teeth were classified according to the severity of fluorosis using the Thylstrup and Fejerskov index and were divided into four groups (TFI scores of 0, 3, 4 and 5) of 10 teeth. Non-fluorosed teeth (TFI score of 0) served as the control group. A self-etching light-cured bonding system, Clearfil SE Bond, and a micro-hybrid light-cured composite, Clearfil AP-X were selected for the study. Buccal surfaces of mounted teeth were ground flat to expose the dentine. Composite cylinders, 4 mm diameter and 4 mm length, were bonded to the treated dentine surfaces. Shear bond strength was measured with an universal testing machine at a cross-head speed of 0.5 mm min-1. After failure, the fracture surfaces were examined under a stereo microscope. The mean bond strength was 24.37 +/- 3.54 MPa for non-fluorosed teeth and varied between 22.72 +/- 3.52 and 27.02 +/- 5.91 MPa for fluorosed teeth. The difference between the mean values for bond strength was not statistically significant (P > 0.05). Adhesive mode of failure was most prevalent in non-fluorosed teeth. It can be concluded that fluorosis does not affect the shear bond strength of composite material to human dentine.