Efficacy of in-office bleaching techniques combined with the application of a casein phosphopeptide-amorphous calcium phosphate paste at different moments and its influence on enamel surface properties.

OBJECTIVES: The aim of this in vitro study was to investigate the efficacy of in-office bleaching technique combined with the application of a casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste (MI Paste-MI) at different moments and its influence on enamel surface properties. METHODS: Eighty bovine dental crowns were randomly allocated into eight groups (n = 10), and bleached with either 35% hydrogen peroxide (HP) or 37% carbamide peroxide (CP). Four different protocols of application of MI were considered: without MI, MI applied before bleaching, MI applied after bleaching, and MI applied both before and after bleaching. Bleaching effectiveness was measured by the VITA EasyShade spectrophotometer utilizing the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*). Color readings were measured at baseline, 7, 14, and 21 days. Hardness and roughness were measured at baseline (T0) and immediately after bleaching (T14). Data were subjected to the two-way ANOVA for repeated measurements and Tukey's test at 5%. RESULTS: HP groups achieved the greatest color change. The application of a CPP-ACP paste did not reduce the efficacy of bleaching peroxides. Samples bleached with CP showed decreased hardness at T14. Samples bleached with HP that received the application of MI before and before/after bleaching did not present hardness decrease at T14. Samples bleached with peroxides only and received MI after bleaching showed increased roughness at T14. CONCLUSIONS: The use of CPP-ACP was able to prevent negative changes in roughness and hardness of bovine enamel when associated to hydrogen peroxide, and might be applied before/after the bleaching protocol.

Enamel properties after tooth bleaching with hydrogen/carbamide peroxides in association with a CPP-ACP paste.

BACKGROUND: This study evaluated the impact of bleaching teeth using blends of a CPP-ACP paste (MI Paste; MI) and carbamide/hydrogen peroxides in different proportions on surface properties of bleached enamel. METHODS: Ninety bovine incisors were bleached with 7.5% hydrogen peroxide (HP), 16% carbamide peroxide (CP), MI and blends of HP or CP:MI at three proportions (1:1, 2:1, 1:2). Hardness and roughness were measured at baseline and after bleaching. Enamel morphology was evaluated by Scanning Electron Microscopy (SEM). The data were analyzed by two-way ANOVA for repeated measurements and Tukey's test. RESULTS: Most of the samples bleached with MI in combination with peroxides presented increased hardness and roughness which were associated to mineral deposition, as observed by SEM images. Blends with higher fractions of MI did not offer superior benefits. CONCLUSIONS: The use of a CPP-ACP paste mixed to carbamide/hydrogen peroxides can decrease adverse side-effects from tooth bleaching on an enamel surface.

Influence of adhesion promoters and curing-light sources on the shear bond strength of orthodontic brackets.

CONTEXT: The effect of different curing units on bond strength of orthodontic brackets is still unclear when utilizing nanofilled composites in comparison with traditional Transbond-XT. AIM: To evaluate the influence of two adhesive promoters and two curing-light units on the shear bond strength (SBS) of orthodontic brackets. SETTINGS AND DESIGN: The factors under study were adhesive promoters (nanofilled composite - Filtek-Z350 flowable restorative and conventional orthodontic adhesive - Transbond XT) and curing-light units (halogen lamp - Ultralux and LED device - Radii-Call). MATERIAL AND METHODS: Forty lower bovine incisors were utilized. The teeth were distributed in four groups (n = 10) according to the combination between adhesive promoters and curing-light units. Scotchbond Multipurpose-Plus and Transbond-XT primer were used to bond Filtek-Z350 Flowable Restorative and Transbond-XT, respectively. After storage in distilled water for 24 h, the brackets were subjected to SBS test at a speed of 0.5 mm/min until bracket debonding. The Adhesive Remnant Index (ARI) was assigned at fractured specimens. STATISTICAL ANALYSIS USED: Analysis of variance and Tukey test were utilized. The Kruskal-Wallis test was used to compare ARI scores between the groups (p<0.05). RESULTS: There was statistically significant difference between the adhesive promoters tested. Transbond-XT showed higher SBS means than Filtek-Z350. There was no statistically significant difference between both curing-light units tested in this study, neither between ARI scores. CONCLUSIONS: The conventional orthodontic adhesive presented higher bond strength than the nanofilled composite, although both materials interacted similarly to the teeth. The curing-light devices tested did not influence on bond strength of orthodontic brackets.

Update on nonsurgical, ultraconservative approaches to treat effectively non-cavitated caries lesions in permanent teeth.

Dental caries on tooth surfaces is still a problem in many industrialized countries. For many years, dentistry was influenced by a mechanical approach characterized by the use of high-speed rotary cutting instruments, and dentists predominantly used surgical methods to address caries. This included radical removal of diseased portions of the tooth, along with material-driven geometric extensions to areas that were assumed to be caries-resistant. This concept of extension for prevention was introduced by G. V. Black and influenced dentists for more than 120 years. Recently, a new paradigm of operative conservatism, sometimes referred to as "minimally invasive dentistry," has gained popularity. This paradigm is designed to promote maximum preservation of healthy dental structures over a lifetime. The aim of this review is to discuss the efficacy of current nonsurgical treatments for non-cavitated caries lesions in permanent teeth. Based on results obtained from clinical trials, this review evaluates treatments such as consumption of CPP-ACP added gums, resin infiltration and fissure sealing. Although in a few cases an invasive approach is needed to arrest caries progression, the non-surgical approach generally provides potential benefits that include conserving structure by delaying intervention or minimizing the operative procedure. All current non-invasive methods are effective in treating non-cavitated caries lesions. The adoption of non-invasive approaches in the management of these lesions can preserve dental tissues, thus increasing tooth longevity.

Preliminary clinical reports of a novel night-guard tooth bleaching technique modified by casein phosphopeptide-amorphous calcium phosphate (CCP-ACP).

Although supervised night-guard bleaching has proved successful for whitening teeth, both mineral loss and tooth sensitivity are still common problems. The present study introduces a novel remineralizer as well as describes the utilization of a possibly low sensitivity supervised night-guard vital tooth bleaching technique. A 22% carbamide peroxide gel was mixed with the casein phosphopeptide-amorphous calcium phosphate-containing MI Paste. The peroxide/MI Paste mixture was prepared with 1 ml of each material until obtaining a homogeneous paste. Five patients were instructed to follow a home bleaching protocol for 3 weeks. The outcome was assessed visually with a Vitapan scale. All subjects presented reduction of at least two Vitapan scale units after bleaching and no sensitivity was reported. The concomitant use of MI Paste and peroxide might not affect the gel effectiveness and still reduce hypersensitivity levels.

Influence of air abrasion and long-term storage on the bond strength of self-etching adhesives to dentin.

This study tested the effects of long-term storage and aluminum oxide air abrasion on the bond strength of self-etching adhesive systems. Extracted human third molars were ground flat with 600-grit SiC paper to expose middle coronal dentin. Clearfil SE Bond and One-Up Bond F were applied to dentin surfaces in accordance with manufacturers instructions with or without previous aluminum oxide 50 microm air abrasion. A crown was built up with the resin composite TPH Spectrum and the specimens were stored in water for 24 hours. The bonded assemblies were vertically sectioned into beams for microtensile bond testing. The beams of each tooth were individually immersed in bottles containing water at 37 degrees C for one day, three and six months; the water was changed daily. The specimens were then subjected to microtensile bond testing. The bond strength data were subjected to ANOVA and Tukey Kramer test. Fractured specimens were analyzed in a scanning electron microscope to determine failure modes. Air abrasion improved Clearfil SE Bond bond strength in the three month evaluation. No significant difference was found between the two adhesives systems, but bond strengths gradually decreased over time. Failure modes varied significantly among groups and were influenced by long-term storage and aluminum oxide air abrasion.

Effect of polymerization modes and resin composite on the temperature rise of human dentin of different thicknesses: an in vitro study.

This in vitro study evaluated the effect of different polymerization modes and the presence of resin composite on the temperature rise (TR) in human dentin of different thicknesses. For this purpose, 90 specimens were assigned to 30 groups (n=3): five polymerization modes (1-conventional; 2-soft-start; 3-high intensity; 4-ramp cure: progressive and high intensity; 5-high intensity with the tip of the light cure at a distance of 1.3 cm for 10 seconds and the tip leaned in the sample); two levels of resin composite presence (absence or presence of resin composite) and three dentin thicknesses (1, 2, 3 mm). During polymerization, temperature was measured by a digital laser thermometer (CMSS2000-SL/SKF). Three-way ANOVA and Tukey tests were performed. There were statistical differences in TR among polymerization modes, presence of resin composite and dentin thicknesses. Within the limits of this study, it can be concluded that 1) conventional and high intensity polymerization modes presented lower TR means, and it was statistically different from soft start, distanced tip and ramp curing polymerization modes; 2) the presence of resin composite showed a statistically significant reduction TR means and 3) the thicker the dentin, the less the temperature rise.

The effect of insertion and photopolymerization techniques on microleakage of class V cavities--a quantitative evaluation.

The aim of this in vitro study was to evaluate by spectrophotometry the influence of the incremental technique and progressive light curing in the microleakage of Class V cavities. Forty samples were prepared with class V cylindrical cavities on the buccal root surface of bovine incisive teeth and filled with composite resin (Z250). The samples were divided into four groups: I: cavity was bulk filled and the composite was light cured for 40 seconds; Group II: cavity was bulk filled and a 'soft-start" polymerization was used; Group III: cavity was filled with the incremental technique in two coats and light cured for 40 seconds; Group IV: cavity was filled with the incremental technique in two coats and light cured with "soft-start" polymerization. After the restoration, the specimens were thermally stressed for 3,000 cycles in bath at 5 +/- 2 degrees C and 55 +/- 2 degrees C, protected with nail enamel, colored with 2% methylene blue and cut into sections. These sections were triturated and the dye was recovered with PA ethanol and the supernatant was evaluated. The data were submitted to ANOVA and the results showed the following averages: bulk filled and conventional photopolymerization (I) 0.06075 microg/ml; bulk filled and progressive photopolymerization (II) 0.04030 microg/ml; incremental insertion and conventional photopolymerization (III) 0.04648 microg/ml; incremental insertion and progressive photopolymerization (IV) 0.04339 microg/ml. No significant statistic differences were observed among the mean values. The Degulux "soft-start" equipment probably emits too high initial light intensity to promote progressive photopolymerization.

Quantitative evaluation of microleakage in Class V cavities using one-bottle and self-etching adhesive systems.

The aim of this in vitro study was to evaluate quantitatively the microleakage in Class V cavities restored with one-bottle and self-etching adhesive systems with and without previous acid etching. Two one-bottle adhesive systems (Single Bond and Prime & Bond 2.1) and one self-etching adhesive system (Clearfil Mega Bond) were used in this study. One hundred and twenty sound human premolar teeth were randomly divided into 6 groups, and 20 Class V restorations were prepared in the root dentin to test each bonding system. Each bonding system was used with and without acid etching. Specimens were prepared, dyed with 2% methylene blue, sectioned, triturated, and evaluated with an absorbance spectrophotometer test in order to quantify the infiltrated dye. Results were statistically evaluated by ANOVA and Tukey-Kramer test. No statistically significant differences were found among the adhesive systems when no etching agent was used. However, the Single Bond adhesive system showed statistically significant lower microleakage means than Clearfil Mega Bond and Prime & Bond 2.1 when 37% phosphoric acid was used. Single Bond and Clearfil Mega Bond adhesive systems presented similar behavior when the manufacturers' instructions were followed.

Effect of irradiation mode and filling technique on resin/dentin bonding strength in Class I cavities.

Factors such as light-curing mode, filling technique and cavity configuration may affect the bonding strength to dentin. This study evaluated the effect of irradiation mode and filling technique on resin/dentin bonding strength on the buccal wall of Class I cavities in human teeth. Occlusal enamel was removed to expose a flat dentin surface. Occlusal cavities (4 x 3 x 3 mm) were prepared in dentin. The adhesive Single Bond was applied according to the manufacturer's instructions and TPH Spectrum composite resin was placed using the following: oblique incremental, horizontal incremental or bulk filling techniques. The composite resin was light-cured either by continuous (600 mW/cm2 for 40 s) or Soft-Start (250 mW/cm2 for 10 s + 600 mW/cm2 for 30 s) modes. Specimens of the control group were obtained by bonding the material to the flat exposed buccal wall of the cavity (C-factor = 1). The teeth were stored in water at 37 degrees C for 24 h and prepared for microtensile testing. Bonded beams of approximately 0.8 mm2 were obtained from the buccal wall and tested with a tension of 0.5 mm/min. Results were analyzed by two-way ANOVA, Tukey's test and Dunnett's test (alpha = 0.05). Incremental placement techniques with both irradiation modes produced higher bonding strength values than the bulk technique (p < 0.05). Bonding strength tested in the cavities had lower values than those obtained in flat dentin surfaces (control group) (p < 0.05), except for incremental fillings using stepped irradiation. Bonding strength to the cavity walls depends on the filling technique and on the irradiation mode of composite resins.

A quantitative method of measuring the microleakage of thermocycled or non-thermocycled posterior tooth restorations.

This study quantified microleakage in restorations made with three packable resin composites-Solitaire, SureFil and P60; one hybrid resin composite-Z250 and an amalgam-Dispersalloy, with or without the thermocycling process. Sixty sound, freshly extracted human molars were sectioned mesiodistally, creating buccal and lingual blocks. One hundred blocks with the flattest surface were selected. Cylindrical cavities with a diameter of 1.85 +/- 0.05 mm and a depth of 1.5 mm were prepared with a special diamond bur. The blocks were randomly assigned to 10 test groups (n = 10): five restorative materials and two thermal stress groups (thermocycled groups at 3,000 cycles at 5 degrees C and 55 degrees C with a dwell time of one minute at each temperature, or non-thermocycled). After the thermocycling test, the samples were immersed in 2% methylene blue for 12 hours. The samples were ground and the powder prepared for analysis in an absorbance spectrophotometer. All the results were statistically analyzed by the Kruskal-Wallis test and the Mann Whitney test. For the non-thermocycled groups, the means (microg/ml) of microleakage were: Amalgam-4.279 (a); Solitaire-4.148 (ab); Z250-3.418 (abc); P60-3.184 (bc); SureFil-2.890 (c). For the thermocycled groups, the means were: Amalgam-7.572 (a); Solitaire-5.471 (a); Z250-4.330 (ab); P60-3.418 (bc) and SureFil-2.779 (c). Thermocycling analysis showed no significant differences between the thermocycled and non-thermocycled groups for each material tested. It was concluded that no test material prevented microleakage. Only SureFil and P60 showed leakage means significantly lower than amalgam, with SureFil showing lower leakage than Solitaire. P60 only showed lower leakage than Solitaire in the thermocycled groups and Z250 showed results similar to the others materials.