Influence of intraoral temperature and relative humidity on the dentin bond strength: an in situ study.

STATEMENT OF THE PROBLEM: The effect of the intraoral environment during adhesive restorative procedures remains a concern, especially in the absence of rubber dam isolation. OBJECTIVE: To evaluate the temperature and relative humidity (RH) at anterior and posterior intraoral sites and their effects on the dentin bond strength of two-step etch-and-rinse adhesive systems. METHODS: Sixty human molars were assigned to six groups according to the adhesive systems (Adper Single Bond Plus and One Step Plus) and intraoral sites (incisor and molar sites). The room condition was used as a control group. Dentin fragments were individually placed in custom-made acetate trays and direct composite restorations were performed. The intraoral temperature and RH were recorded during adhesive procedures. Then, specimens were removed from the acetate trays and sectioned to obtain multiple beams for the microtensile bond strength test. In addition, the adhesive interface morphology was evaluated through scanning electron microscopy. Intraoral conditions were statistically analyzed by paired Students' t-tests and the bond strength data by two-way analysis of variance and Tukey test (α = 0.05). RESULTS: The posterior intraoral site showed a significant increase in the temperature and RH when compared with the anterior site. However, both intraoral sites revealed higher temperatures and RH than the room condition. In regards to the adhesive systems, the intraoral environment did not affect the bond strength, and the One Step Plus system showed the highest bond strength means. CONCLUSION: Despite the fact that remarkable changes in the intraoral conditions were observed for both anterior and posterior sites, the intraoral environment was not able to compromise the immediate dentin bond strength. CLINICAL SIGNIFICANCE: Some conditions of intraoral temperature and relative humidity may not impair the dentin bond strength of two-step etch-and-rinse adhesive systems. Thus, an adequate relative isolation seems to be a good alternative under the specific clinical conditions in which rubber dam isolation is either impossible or very difficult to perform.

Cigarette smoke: effects on water sorption and solubility of restorative dental composites.

Although scientific evidence has shown the effects of tobacco on changes in the color of composite resins, the association between tobacco exposure and the physical properties of composite resins has not been thoroughly investigated. The purpose of this study was to evaluate the effects of cigarette smoke products on water sorption and solubility of microfilled, microhybrid, and nanofilled composite resins (Durafill VS, Filtek Z250, and Filtek Z350 XT, respectively). Ten discs were prepared of each material and divided into 2 groups (n =5), according to cigarette smoke exposure. Specimens were first desiccated until a constant mass was obtained (M1). Then half of the samples were immersed in deionized water while the other half were exposed daily to tobacco smoke, then washed and stored in deionized water. After 21 days, the resin discs were measured (M2) and placed in desiccators until constant mass was achieved (M3). Water sorption and solubility were calculated and the data was statistically analyzed. Water sorption revealed significant differences among the composite resins. The Filtek Z350 XT exhibited the highest water sorption, followed by Durafill VS and Filtek Z250. Cigarette smoke significantly increased water sorption for all products, but only the solubility of Durafill VS showed a significant difference. Filtek Z250 demonstrated significantly lower solubility than Durafill VS, and Filtek Z350 XT had intermediate values. These results indicated that water sorption and solubility varied among the products, and tobacco smoke may alter the physical properties of resin-based materials.

Microinvasive esthetic approach for deep enamel white spot lesion.

The white spot lesion on the dental enamel is an optical alteration that compromises the esthetics of smile. It can be caused by many factors, among them, defects in mineralization and formation of tooth enamel. Resin infiltrants are agents that penetrate, by capillarity, through the pores of the demineralized or hypomineralized enamel, altering the refractive index (RI) of the tooth structure and totally or partially masking the appearance of the white spot. The aim of this work was to report the use of resin infiltration to minimize the visualization of white spot lesion, present in an upper central incisor, as a microinvasive approach for the esthetic treatment of deep enamel hypomineralization. A 20-year-old female patient sought care with the esthetic complaint of extensive white spot lesion on the buccal face of her upper right central incisor. The diagnosis established was a deep white stain associated with the incisor molar hypomineralization syndrome, and the treatment of choice for the resolution of the case was the application of the Icon® resin infiltrant (DMG, Hamburg, Germany). To reach the body of the lesion, three cycles of acid erosion, using 15% HCl, were necessary to obtain a satisfactory aspect of masking the white lesion. A camouflage effect of the deep white spot lesion was achieved with the use of the resin infiltration, without the need of additional and irreversible wear of the dental structure.

Cigarette smoke combined with staining beverages decreases luminosity and increases pigmentation in composite resin restorations.

This study evaluated the effect of cigarette smoke combined or not with colored beverages on the color change of a composite resin before and after repolishing procedures. Composite specimens were allocated into six groups (N = 10): 1) control (no colorant); 2) cigarette smoke; 3) coffee; 4) coffee and cigarette smoke; 5) red wine; and 6) red wine and cigarette smoke. During 21 days, groups 2, 4, and 6 were exposed daily to the smoke from 20 cigarettes, and groups 3, 4, 5, and 6 were immersed in coffee or red wine for 4 minutes each day. Color measurements were performed with a spectrophotometer at baseline, after 21 days, and after repolishing procedures. Statistical analysis indicated the exposure to cigarette smoke and staining beverages resulted in decreased luminosity (P = .0001) and increased red pigmentation in most experimental groups (P < .05). In groups 3, 4, and 6, an increased yellowish coloration (P = .001) was observed. Irrespective of the experimental group, total color changes were clinically significant (AE > 7.5). Repolishing resulted in greater luminosity, as well as decreased yellow pigmentation (P < .05). It could be concluded that combined staining agents such as cigarette smoke and red wine irreversibly change resin color regardless of the use of repolishing procedures.

Planning and orthodontic preparation for maxillary incisors reshaping.

INTRODUCTION: Having a beautiful smile is the main desire of people seeking dental treatment. To achieve this goal, many variables must be considered. These include tooth alignment, color, shape and size, besides their harmonious relationship with the lips and face. An individualized diagnosis is essential to achieve the best result. Within this context, facial analysis and the characteristics of shape, size and position of maxillary incisors play a key role. METHODS: This paper describes clinical situations in which interdisciplinary treatment was performed to achieve esthetic results in a conservative manner and ensuring greater stability. In most cases requiring reshaping of maxillary incisors for esthetic reasons, prior orthodontic movement is essential. The main focus of this paper is to discuss the many variables involved in these situations. RESULTS AND CONCLUSION: The results of treatments described in this paper were obtained by means of a multidisciplinary approach, involving Orthodontics and Esthetic Dentistry, acting in harmony and recognizing their possibilities and limitations, in order to offer patients the best esthetic solution for their smile. The best treatment option is not always the easiest or fastest. The dentist, as a health professional, should consider the patients' wishes but also perform treatments with minimal intervention, and the best and most predictable esthetic result, also focusing on function and health.

Color stability of an artificially aged nanofilled composite resin post-cured with different techniques.

Background. Post-cured composite resins exhibit improvements in physical and mechanical properties due to additional polymerization conversion. However, the post-curing techniques might influence the color stability of composite resin materials. Thus, this study evaluated the color stability of a nanofilled composite resin (Filtek Z350 XT - 3M ESPE) subjected to different post-curing techniques. Methods. Sixty samples (color A2) were randomly allocated to six experimental groups (n=10): G1: photoactivation (P) (control); G2: P + microwave oven with distilled water; G3: P + microwave oven without distilled water; G4: P + conventional oven; G5: P + dry-heat sterilizer; G6: P + steam autoclave. All the groups were stored in distilled water for 60 days and immersed daily in 5 mL of a coffee solution for 3 minutes. The color readings (CIEL*a*b* system) were performed at two different time intervals, initially and after 60 days, in a reflectance spectrophotometer (UV-2600; Shimadzu). The colorimetric readings were performed using the Color Analysis software (CIEL*a*b* system). Results. Group G6 exhibited significantly low values of total color change (ΔE=13.16). The control (ΔE=15.32) and G5 (ΔE=15.49) groups exhibited intermediate values, with no difference between them. In turn, the groups in which the resin was heated in a microwave (G2 ΔE=18.55 and G3 ΔE=19.45) exhibited the most significant color changes (one-way ANOVA and Tukey test, P ≤0.05). Conclusion. Steam autoclave post-polymerization increased the color stability of the nanofilled resin subjected to artificial aging and coffee immersion.

Evaluation of dentin hardness and bond strength at different walls of class II preparations.

PURPOSE: The aim of this study was to evaluate the Knoop hardness number (KHN) of dentin and the microtensile bond strength (microTBS) at different walls of MOD preparations, and the correlation between microTBS and the KHN of dentin. MATERIALS AND METHODS: Human molars with MOD preparations were allocated into 3 groups according to the preparation wall (axial, gingival, pulpal). Each tooth was sectioned into halves, resulting in two similar preparation walls: one was used for measuring the KHN of dentin and the other for microTBS testing. Flat surfaces of the respective walls were obtained by cutting away adjacent walls. For the KHN measurement, twelve indentations were performed along the preparation wall (50 g/15 s). For microTBS testing, specimens were distributed into 3 groups according to the adhesive system (Adper Single Bond Plus/SB, Clearfil SE Bond/SE, Adper Prompt/AP). Composite blocks were built over surfaces; specimens were sectioned (3 slabs/wall) and trimmed to an hourglass shape (1 mm(2)). RESULTS: The KHN of dentin walls was significantly different (ANOVA/Tukey); pulpal wall > axial wall > gingival wall. The effect of preparation walls on microTBS was dependent on the bonding system (2-way ANOVA/Tukey's test). SB had higher bond strength than the other systems at the gingival wall; and higher than SE at the axial wall. At the pulpal wall, SE presented a higher mean compared to AP. A significant negative correlation between microTBS and KHN was observed at the gingival wall. CONCLUSION: It could be concluded that dentin structure can affect bond strengths, but the impact of the substrate varies according to the type of adhesive system.

Morphologic texture characterization allied to cigarette smoke increase pigmentation in composite resin restorations.

STATEMENT OF THE PROBLEM: The staining effect of tobacco smoke on resin color is clinically observed. However, there is no evidence determining whether this staining is increased on texturized surfaces or if the color change is superficial and can be removed by repolishing procedures. OBJECTIVE: To evaluate the effect of tobacco smoke on the color of a composite with smooth or texturized surfaces, before and after repolishing. MATERIALS AND METHODS: Forty composite specimens were allocated into four groups (N = 10): Smooth surface not exposed (G1) and exposed to tobacco smoke (G2), texturized surface not exposed (G3), and exposed to tobacco smoke (G4). During 21 days, G2 and G4 were daily exposed to the smoke from 20 cigarettes. Color measurements were carried out at baseline, after 21 days, and after repolishing. Variables L* (luminosity), b* (blue-yellow), and DeltaE (total color change) were statistically analyzed (repeated measures analysis of variance/Tukey). RESULTS: Texturized and smooth specimens presented similar luminosity at baseline. Tobacco smoke significantly reduced L* in G2 and G4, and increased b* in G4. After repolishing, L* increased and b* reduced in stained groups, but values continued to be different from baseline ones. Repolishing significantly reduced DeltaE, but values from stained groups were still greater than that from unstained groups. CONCLUSION: Tobacco smoke changes the color of composite, and surface texture can increase the staining. Repolishing reduces superficial staining, but this procedure may not return the composite to baseline color. CLINICAL RELEVANCE: Smokers that will receive anterior composite restorations should be warned about the negative cosmetic effect of the smoking habit on the color of restorations.

Effect of surface sealant and repolishing procedures on the color of composite resin exposed to cigarette smoke.

This study evaluated the effect of cigarette smoke on the color of composite resins, with and without the application of a surface sealant and before and after the restorative material was repolished. Twenty composite resin specimens were divided into two groups (n = 10); one of which received a surface sealant. Both groups were exposed daily to the smoke of 20 cigarettes. Color analyses were performed using a spectrophotometer at different intervals: prior to cigarette smoke exposure (baseline), 21 days after cigarette smoke exposure, and after the specimens were repolished using aluminum oxide discs. Cigarette smoke caused a decrease in lightness (L*), especially in samples that received the sealant (p = 0.014). At 21 days, there was an increase in yellow pigment for both groups, with higher values (p = 0.00001) and predominant red pigmentation in the samples that received sealant. An increase in lightness and a decrease in yellow pigments (p < 0.05) were reported in both groups after repolishing. Cigarette smoke significantly altered the color of the composite resin (DeltaE > or = 10.34), especially in the specimens that received the sealant. In this study, the sealant tested intensified cigarette staining, and although repolishing decreased surface pigmentation, it was unable to restore the original color of the composite resin.

Intraoral environment conditions and their influence on marginal leakage in composite resin restorations.

Color matching in the anterior superior incisor region (ASIR) is very difficult when using a rubber dam during restorative procedures. This study measured temperature/relative humidity parameters in the ASIR and evaluated the influence of the inhalation/downtime/exhalation mouth-breathing cycle on microleakage in composite resin restorations performed in the region, using three different adhesive systems. Sixty bovine incisors were randomly assigned to six groups (n=10) according to environmental conditions (laboratory environment or intraoral conditions) and the three adhesive systems being tested (Prime & Bond NT (PB), Single Bond (SB) and Clearfil SE Bond (CL)). The composite resin restored specimens were thermocycled (800 cycles, 5-55 degrees C), immersed in a 2% methylene blue-buffered solution and sectioned longitudinally The dye penetration on the margin of the restoration was evaluated and non-parametric statistical analyses were performed. The temperature and humidity parameters in the ASIR showed significant differences when compared to the laboratory environment. Restorations performed in the ASIR environment showed no increases in microleakage. As it was shown that temperature/humidity in ASIR do not affect marginal sealing in direct composite resin restorations negatively, better color matching can be safely achieved without the use of a rubber dam.

Repair Bond Strength and Leakage of Non-Aged and Aged Bulk-fill Composite.

PURPOSE: This study evaluated repair protocols of a non-aged and aged bulk-fill composite in terms of bond strength and leakage. MATERIALS AND METHODS: Ninety-six bulk-fill resin specimens were constructed; half were submitted to thermocycling. Specimens were divided into six groups (n = 16) according to the repair treatments: CG: no repair (control group); Ad: adhesive; DbAd: abrasion with diamond bur + adhesive; SbAd: sandblasting + adhesive; DbSiAd: abrasion with diamond bur + silane + adhesive; and SbSiAd: sandblasting + silane + adhesive. Resin blocks were bonded to the treated surfaces to simulate repair, and the specimens were submitted to microtensile bond strength testing. The failure area was evaluated under a stereomicroscope (40X magnification), and leakage after specimen immersion in silver nitrate solution for 24 h was evaluated under a microscope (200X magnification). Three-way ANOVA (surface treatment, chemical agent, aging) and Tukey's test were performed. RESULTS: Ad and DbAd groups showed the lowest bond strengths, while Ad was the only group negatively influenced by aging. The other groups were statistically similar to the CG in both conditions. All groups exhibited leakage, but groups without silane presented a greater percentage of leakage, mainly when diamond burs were used. Thermocycling did not influence leakage, nor did surface treatment in groups with silane. CONCLUSION: For composite repair, the use of silane is recommended, mainly when diamond burs are used as a mechanical surface treatment.

The effect of coffee solution on tooth color during home bleaching applications.

PURPOSE: To quantify the change in color of human and bovine teeth exposed to a coffee solution during a 16% carbamide peroxide (16% CP) home application bleaching treatment using photoreflectance analysis. METHODS: 40 enamel slabs (4 x 4 x 2 mm) were obtained from seven unerupted third human molars and seven bovine incisors, which were allocated into four groups: G1: human control group whitened and not exposed to a coffee solution; G2: bovine control group whitened and not exposed to a coffee solution; G3: human teeth whitened and exposed to a coffee solution; G4: bovine teeth whitened and exposed to a coffee solution. The home bleaching procedure was performed using 16% CP gel applied in a 1 mm-thick layer on the tooth surface over a period of 6 hours per day, for 28 days. Tooth color was evaluated using photoreflectance analysis throughout the bleaching procedure at intervals of 7, 14, 21 and 28 days, and posttreatment at 7, 15 and 30 days. Results were statistically analyzed using ANOVA and Tukey-Kramer tests. RESULTS: After 28 days of bleaching treatment, no significant difference was detected between photoreflectance analysis of specimens exposed to coffee solution and specimens not exposed to coffee solution (P < 0.05). However, when the teeth were exposed to a coffee solution during home bleaching treatment, the whitening effect was observed to be less stable (P < 0.05). Bovine and human enamel substrates behaved similarly in terms of staining and bleaching effects, although they presented inherent differences in color (P < 0.05).

24 hours and 3-months bond strength between dual-cured resin cements and simplified adhesive systems.

This study evaluated the bonding compatibility between dual-cured resin cements and simplified adhesive systems (one-step self-etch and two-step etch & rinse), measured after 24 hours and 3 months. The occlusal dentin surfaces of 24 human third molars were exposed and flattened. Teeth were randomly assigned to 3 groups and treated with different combinations of adhesive system and resin cement [G1-Single Bond/Rely X ARC (SB/RX); G2-Excite DSC/Variolink II (EX/VR); G3-Adper Prompt/Rely X ARC (AD/RX)]. Indirect composite restorations were cemented on flattened surfaces, and sectioned to obtain multiple bonded beams for the microtensile bond strength test. The beams from each tooth were tested under tension after 24 hours and 3 months (ANOVA/ Tukey's test, alpha=5%). Failure patterns were evaluated with scanning electron microscopy. After 24h, AD/RX presented the lowest bond strength mean values. AD/RX specimens did not withstand three months storage. SB/RX and EX/VR presented similar bond strengths in both periods tested. The association AD/RX resulted in low bond strength mean values, especially after storage. Cementing indirect restorations using one-step self-etch adhesive systems and dual-cured resin cements would be clinically unreliable.

Dentin bonding on different walls of a class II preparation.

PURPOSE: To evaluate the bond strength on different cavity walls of Class II preparations. Different bonding systems and the effect of thermomechanical cycling were investigated. MATERIALS AND METHODS: Human third molars received MOD preparations with dentin margins. Teeth were randomly assigned to 18 groups (n=5) according to the combination of cavity wall (axial, occlusal, and gingival), bonding system (Single Bond Plus, Clearfil SE Bond, and Adper Prompt) and the occurrence of thermomechanical cycling. Restorations were concluded with Filtek Z250 composite. Specimens were sectioned according to the respective cavity wall (4 slabs/restoration), and the adhesive interface was trimmed to an hourglass shape (1 mm2). Slabs were tested under tension, and failure mode was observed. Bond strength data were analyzed with three-way ANOVA/Tukey's test. RESULTS: Single Bond Plus and Clearfil SE Bond performed similarly under most experimental conditions. Single Bond Plus presented similar bond strength on the three cavity walls, regardless of the aging condition. Clearfil SE Bond exhibited significant differences among cavity walls: the occlusal wall showed higher means in both aging conditions. Non-aged gingival walls and aged axial and gingival walls yielded lower means. Non-aged Adper Prompt produced similar bond strengths on the three cavity walls. After thermomechanical cycling, the gingival wall showed lower means. CONCLUSION: The effect of cavity walls was dependent on the bonding system and thermomechanical cycling. Adper Prompt demonstrated bond strengths lower than Single Bond Plus or Clearfil SE Bond under most experimental conditions.

Planning and orthodontic preparation for maxillary incisors reshaping

ABSTRACT Introduction: Having a beautiful smile is the main desire of people seeking dental treatment. To achieve this goal, many variables must be considered. These include tooth alignment, color, shape and size, besides their harmonious relationship with the lips and face. An individualized diagnosis is essential to achieve the best result. Within this context, facial analysis and the characteristics of shape, size and position of maxillary incisors play a key role. Methods: This paper describes clinical situations in which interdisciplinary treatment was performed to achieve esthetic results in a conservative manner and ensuring greater stability. In most cases requiring reshaping of maxillary incisors for esthetic reasons, prior orthodontic movement is essential. The main focus of this paper is to discuss the many variables involved in these situations. Results and Conclusion: The results of treatments described in this paper were obtained by means of a multidisciplinary approach, involving Orthodontics and Esthetic Dentistry, acting in harmony and recognizing their possibilities and limitations, in order to offer patients the best esthetic solution for their smile. The best treatment option is not always the easiest or fastest. The dentist, as a health professional, should consider the patients' wishes but also perform treatments with minimal intervention, and the best and most predictable esthetic result, also focusing on function and health.

RESUMO Introdução: Ter um sorriso bonito é o principal desejo de quem busca um tratamento odontológico. Para se alcançar esse objetivo, muitas variáveis devem ser consideradas. Entre elas, estão alinhamento, cor, forma e tamanho dos dentes, além da sua relação harmoniosa com os lábios e a face. O diagnóstico individualizado é essencial para se alcançar o melhor resultado. Nesse contexto, a análise facial e as características de forma, tamanho e posição dos incisivos superiores têm papel primordial. Métodos: O presente artigo descreve situações clínicas em que o tratamento interdisciplinar foi realizado para alcançar resultados estéticos de modo conservador e garantindo maior estabilidade. Na maioria dos casos em que os incisivos superiores precisam ser reanatomizados por razões estéticas, a movimentação ortodôntica prévia é fundamental. O principal foco desse trabalho é a discussão das muitas variáveis envolvidas nessas situações. Resultados e Conclusão: Os resultados dos tratamentos descritos nesse artigo foram obtidos a partir de um planejamento realizado em equipe - Ortodontia e Dentística, trabalhando em harmonia, reconhecendo as suas possibilidades e limitações, são capazes de oferecer aos pacientes a melhor solução estética para o seu sorriso. A melhor alternativa de tratamento nem sempre é a mais fácil ou a mais rápida. O cirurgião-dentista, como profissional de saúde, deve acolher os desejos dos pacientes, mas realizar tratamentos com intervenção mínima e com o melhor e mais previsível resultado estético, com foco dirigido, também, à função e saúde.

A Conservative Esthetic Approach Using Enamel Recontouring and Composite Resin Restorations.

Conservative clinical solutions, predictable esthetic, and immediate outcomes are important concepts of restorative dentistry. The aim of this case study was to recognize the selective enamel removal as an interesting conservative alternative to achieve optimal esthetic results and discuss the clinical protocol. This clinical report described an alternative esthetic and conservative treatment to transform the long and sharp aspect of the maxillary canines with a slightly aggressive aspect into features of slightly curved teeth with delicate lines. An accurate diagnostic and esthetic analysis of the smile was initially performed. The selective enamel removal was performed, and direct composite restoration was strategically placed. Clinical assessment showed good esthetic outcomes, enabling a smile harmony with an immediate, simple, and lower-cost technique. Practitioners should be exposed to conservative approaches to create esthetic smiles based on the selective enamel removal technique combined with composite resin.

Effect of ceramic thicknesses and opacities on water sorption and solubility of a light-curing resin cement by different units

Aim: This study evaluated the water sorption and solubility of a light-cured resin cement, under four thicknesses and four opacities of a lithium disilicate ceramic, also considering three light-emitting diode (LED) units. Methods: A total of 288 specimens of a resin cement (AllCem Veneer Trans ­ FGM) were prepared, 96 samples were light-cured by each of the three light curing units (Valo ­ Ultradent / Radii-Cal ­ SDI / Bluephase II ­ Ivoclar Vivadent), divided into 16 experimental conditions, according to the opacities of the ceramic: High Opacity (HO), Medium Opacity (MO), Low Translucency (LT), High Translucency (HT), and thicknesses (0.3, 0.8, 1.5, and 2.0 mm) (n = 6). The specimens were weighed at three different times: Mass M1 (after making the specimens), M2 (after 7 days of storage in water), and M3 (after dissection cycle), for calculating water sorption and solubility. Results: The higher thickness of the ceramic (2.0 mm) significantly increased the values of water sorption (44.0± 4.0) and solubility (7.8±0.6), compared to lower thicknesses. Also, the ceramic of higher opacity (HO) generated the highest values of sorption and solubility when compared to the other opacities, regardless of the thickness tested (ANOVA-3 factors / Tukey's test, α = 0.05). There was no influence of light curing units. Conclusion: Higher thicknesses and opacities of the ceramic increased the water sorption and solubility of the tested light-cured resin cement

The influence of sodium hypochlorite and root canal sealers on post retention in different dentin regions.

This study evaluated the influence of 5.25% NaOCl irrigant and root canal sealers on post retention in different dentin regions. Seventy-two human incisors were decoronated at the cemento-enamel junction and randomly divided into six groups (n=12) according to irrigant and sealer technique: G1-Distilled water (DW) without sealer; G2-DW + AH Plus (Dentsply/Maillefer); G3-DW + Endofill (Dentsply/Maillefer); G4-5.251%NaOCl without sealer; G5-5.25% NaOCl + AH Plus; G6-5.25% NaOCl + Endofill. Specimens were stored in a humid environment for 30 days at 37 degrees C and were prepared with FRC Postec's drills for post insertion. The posts were cemented with Excite DSC/Variolink II (Ivoclar/Vivadent). The specimens were sectioned through their long axis into three dental slices approximately 2.5 mm each, representing the cervical (C), middle (M) and apical (A) thirds of the root preparation. After calculating the adhered area of the specimens, they were submitted to the push-out test in a universal testing machine. The data were submitted to an analysis of variance (ANOVA) at a 5% significance level and to the Tukey test (p<0.05). The mean values (MPa) obtained for cervical, middle and apical areas of the root preparation, respectively, were: G1=8.6; 12.5 and 14.3, G2=13.5; 15.4 and 16.9; G3=6.9; 10.0 and 12.1; G4=13.0; 14.9 and 15.4; G5=11.3; 13.5 and 18.0; and G6=11.0; 11.8 and 11.5. Based on the results, the eugenol-based sealer (Endofill) resulted in significantly lower mean retention strength values compared with the resin-based sealer (AH Plus). The apical region showed the greatest retention. The lowest resistance to dislodgment was found in the cervical region, mainly in the groups that used distilled water for irrigating the root canal.

Microtensile bond strength of light- and self-cured adhesive systems to intraradicular dentin using a translucent fiber post.

This study evaluated the bond strength of a light- and self-cured adhesive system to different intraradicular dentin areas (cervical, middle and apical thirds). Twenty single-rooted teeth were instrumented and their roots were prepared to receive a #2 translucent fiber post (Light Post). The root canals were irrigated with 0.5% sodium hypochlorite for one minute, rinsed with water and dried using paper tips. The teeth were divided into two groups (n=10): Single Bond [SB] (light-cured) and Scotchbond Multi-Purpose Plus [SBMP] (self-cured). To avoid polymerization of the materials through the root lateral walls, the teeth were placed in a silicone mold and the adhesives applied with a thin microbrush according to manufacturer's instructions. The resin cement, Rely X ARC, was inserted into the root canals using Lentulo burs. The post was then placed and the light-curing procedure was carried out for 40 seconds (+/-500 mW/cm2). The roots were kept in a 100% relative moisture environment for 24 hours and stored in distilled water for an additional 24 hours. Each root was perpendicularly sectioned into 1-mm thick sections, resulting in approximately four slices per region. Dumbbell-shaped slices were obtained by trimming the proximal surfaces of each slice using a diamond bur until it touched the post. The bonded area was calculated, slices were attached to a special device and submitted to microtensile testing at 1 mm/minute crosshead speed. Data were analyzed using ANOVA and Tukey's test. The mean bond strength values (MPa) were: SBMP: cervical=10.8a, middle=7.9b%, apical=7.1bc; SB: cervical=8.1b, middle=6.0c, apical=6.9b. Significant differences were found between adhesive systems only for the cervical third. The cervical region showed higher mean bond strength values than the middle and apical regions (p<0.0001).

Microleakage at the composite-repair interface: effect of different surface treatment methods.

This study evaluated microleakage at the composite-repair interface after using different methods of surface treatment. Eighty resin composite specimens (Filtek Z250, 3M Dental Products) aged in artificial saliva for three months were divided into four groups (n=20) according to the following surface treatment methods: untreated control-no roughening or abrasion of the surface; roughening with diamond burs; jet prophylaxis with sodium bicarbonate particles and air abrasion with 50 microm aluminum oxide particles. Each method was examined using scanning electron microscopy (SEM) to evaluate changes in surface topography. All groups were then etched with 37% phosphoric acid, coated with a bonding agent (Single Bond, 3M Dental Products) and received new resin applications. The samples were then thermocycled (800 cycles/5 degrees C to 55 degrees C [+/- 2]) and immersed in 2% methylene blue buffered dye solution (7.0 pH) for four hours. Three examiners measured the extent of microleakage in a stereoscope microscope using four representative scores. For all experimental groups, no significant difference in repair microleakage was identified by the Kruskal-Wallis test (p>0.05). Therefore, different testing methods of surface treatment showed the same effect on dye penetration along the repair interface.