Influence of airborne particle abrasion on dentin bonding effectiveness of a 2-step universal adhesive.

OBJECTIVE: To determine the effect of airborne particle abrasion (APA) on micro-tensile bond strength (µTBS) to dentin using different air-abrasion/polishing powders. METHODS: The bonding effectiveness of G2 Bond Universal (G2B), used in etch-and-rinse (E&R) and self-etch mode (SE), was tested on bur-cut dentin and dentin air abraded/polished using six different powders (aluminum oxide 29 µm (AO29) and 53 µm (AO53), aluminum trihydroxide (AT), sodium bicarbonate (SB), sodium bicarbonate soft (SBsoft) and bioactive glass (BG); Velopex). Adhesive-composite resin specimens were immersed in distilled water at 37 °C for one week and cut into microspecimens. Half of the specimens were subjected to 50,000 thermocycles (aged). Immediate and aged µTBS to dentin were measured. Statistical analysis was performed using linear mixed-effects (LME) modeling (p < 0.05). RESULTS: Comparing the aged bond strengths to air-abraded/polished dentin with bur-cut dentin, pretreatment with SB and SBsoft in combination with G2B used in E&R mode, and BG air polishing in combination with both application modes (E&R, SE), resulted in a significantly higher bond strength. Dentin bond strength was only significantly lower when air abraded with AO29 and using G2B in SE mode. Aging did not significantly influence bond strength for both application modes (E&R, SE), except for AO29 and AT-treated dentin, where bond strengths decrea sed significantly using G2B in SE mode. In general, G2B reached significantly higher bond strengths on air-abraded/polished dentin in E&R mode than in SE mode. CONCLUSION: Air-abrasion/polishing did not impair dentin bond strength using G2B, except when dentin was air abraded with AO29 and using G2B in SE mode. Air polishing positively influenced the bond strength to dentin in specific groups. CLINICAL SIGNIFICANCE: APA is safe concerning bonding to dentin. The E&R application mode is preferred using G2B as adhesive on air-abraded/polished dentin. Air polishing with BG positively influenced dentin bond strength for both application methods.

Effect of Extra Hydrophobic Resin Layer on Bonding of Universal Adhesive Systems to Enamel.

OBJECTIVE: The objective of this study was to compare the effect of solvent in universal adhesives (UA) and the application of an extra layer of hydrophobic bonding resin on enamel shear bond strengths (SBS). METHODS AND MATERIALS: Crowns of 224 bovine mandibular incisors were embedded in acrylic resin, wet-polished up to 600-grit silicon carbide paper and assigned to 3 UAs with different solvents (n=32): ethanol-based UA (ADU, AdheSE Universal, Ivoclar Vivadent); isopropanol-based UA (PBU, Prime&Bond Universal, Dentsply Sirona); and acetone-based UA (OPT, OptiBond Universal, Kerr Co). The same UAs were also applied with an extra layer of a hydrophobic bonding resin (HLB, Heliobond, Ivoclar Vivadent): ADU + HLB; PBU + HLB; and OPT + HLB. HLB alone was used as control. Enamel was etched with 37.5% H3PO4 (Kerr Gel Etchant, Kerr Co) for 15 seconds, rinsed with water, and air dried. UAs were applied according to the respective manufacturer's instructions. After adhesive application, composite cylinders (Filtek Z250, 3M Oral Care) were built up and light-cured (40 seconds/increment, 40 J/cm2) keeping the light tip in contact with the mold. Specimens were stored in water for 24 hours (24H) or for 6 months (6M). A knife-edged metallic rod (Ø=2.8-mm semicircular notch) loaded the composite cylinders until fracture. Mode of failure was analyzed with optical microscopy (40×). Statistics included twoway analysis of variance (ANOVA; adhesive strategy and water storage) and Tukey honestly significant difference (HSD) post hoc test (α=95%). RESULTS: Mean enamel SBS ranged from 3.6 (±2.2) MPa (HLB/6M) to 24.7 (±7.1) MPa (ADU + HLB/6M). ANOVA revealed significant differences for adhesive strategy (p≤0.001) but no significant differences for water storage (p>0.05). All UAs resulted in similar mean enamel SBS with or without an extra layer of HLB at 24H. After 6M, only ADU resulted in higher enamel SBS when an extra layer of HLB was applied. All UAs resulted in higher mean enamel SBS than HLB (control). Most failures were adhesive exception for PBU/HLB/6M, which had mostly mixed failures. CONCLUSIONS: UAs resulted in statistically higher enamel SBS than the nonsolvated hydrophobic bonding resin (control), regardless of the solvent in their composition. Application of an extra layer of hydrophobic bonding resin over UAs did not improve mean enamel SBS for isopropanol- and acetone-based UAs but did improve mean enamel SBS for the ethanol-based UA after 6M. Resin composite bonding to enamel using a hydrophobic bonding resin alone is not recommended.

Spatial dynamics of Amazonian commercial fisheries: an analysis of landscape composition and fish landings.

Amazonian commercial fishing is artisanal, and landings can be influenced by the flood pulse, the consumer market, the level of exploitation of species, habitat quality and vegetation cover. In this study, landscape variables and the river level were evaluated as possible drivers in the composition of catches landed in three regions of the Solimões-Amazon River. Fish landing data were collected in the upper and lower Solimões River and lower Amazon River. Fishing locations were mapped with information from fishers, civil defense departments and from the literature. Information related to river level and landscape was acquired from databases available online. Maps with the the radius of action of the fishing fleet and the quantification of landscape variables were made for periods of high and low-water, and non-metric multidimensional scaling analysis (nMDS) with catches by species, by region and hydrological period were performed. The largest operating radius of the fishing fleet was of 1,028 km and was identified in the lower Amazon River, which is probably due to the larger size of the consumer market, vessel characteristics and level of exploitation of the species near the landing center. The proportion of vegetation cover was reduced from 87% in the upper stretches of the Solimões River to 46% in the lower stretches. The upper and lower Solimões River regions presented a greater variety of species in the composition of landings. It was identified that the composition of landings between the three analyzed regions possibly varied according to the availability of habitats, indicating the importance of landscape variables for fish landings.

Three-year Follow-up of Conservative Direct Composite Veneers on Eroded Teeth.

This clinical case describes an esthetic rehabilitation of a young patient presenting with erosive tooth wear. The etiological factors for the erosion in this clinical case was excessive carbonated beverages and lemon water intake. The patient's main complaint was the yellowish aspect of her smile. The treatment procedure selected was direct resin composite veneers in the six maxillary anterior teeth. A three-year follow-up of the case is presented. The three-year follow-up showed a successful clinical performance of the treatment procedure after a finishing/polishing protocol.

Better Glass-fiber Post Preservation in Teeth with Ferrule When Subjected to Chewing.

OBJECTIVES: To evaluate the influence of ferrule effect and mechanical fatigue aging on glass-fiber post push-out bond strength (PBS) to root-canal dentin at different root thirds of premolars. METHODS AND MATERIALS: Thirty-two sound maxillary premolar teeth were collected, and randomly assigned to two experimental groups (n=16): 'Remaining Dentin Ferrule' (RDF) = coronal crown cut 2.0 mm above the cementoenamel junction (CEJ); 'Without Dentin Ferrule' (WDF) = coronal crown cut at the cemento-enamel junction. Teeth were endodontically treated, post spaces were prepared up to 10.0-mm depth from CEJ, and glass-fiber posts were cemented using a dual-cure self-adhesive composite cement. Standardized cores were built using a light-cure composite, upon which tooth cores were prepared using a 1.5-mm taper ogival-end diamond bur. Crowns were handmade using self-cure acrylic resin and cemented using the aforementioned composite cement. Half of the specimens were subjected to 1,200,000 cycles of mechanical fatigue in a chewing simulator (F = 'Fatigue'), while the other half were stored in distilled water at 37°C for 1 week (C = 'Control'). All specimens were horizontally sectioned into 1.0-mm thick slices prior to PBS test; the failure modes were assessed using stereomicroscopy and scanning electron microscopy (SEM). Data were analyzed for each root third using two-way analysis of variance (ANOVA) followed by Tukey HSD post-hoc test; frequency distribution was compared by Chi-square test (α=0.05) and post-hoc comparisons with Bonferroni. RESULTS: The mean PBS in MPa (SD) were = RDF_F = 10.4 (2.9); WDF_F = 6.9 (1.7); RDF_C = 14.5 (2.7); WDF_C = 14.2 (2.9). Similar PBS were found for the root thirds. For all root thirds, significant differences were found for both the factors Dentin Ferrule and Fatigue, and their interaction (p<0.05). The lowest PBS was found for specimens without dentin ferrule subjected to chewing fatigue (p<0.001). Most failures occurred at the composite cement/dentin interface, followed by mixed and composite cement/glass-fiber post interfacial failures. There was a significant increase in mixed failures for the WDF_F group (p<0.001). CONCLUSION: Absence of 2.0-mm remaining dentin ferrule in premolars resulted in a higher decrease of the glass-fiber posts' PBS to dentin after mechanical fatigue, irrespective of root third.

Effect of LED Light-Curing Spectral Emission Profile on Light-Cured Resin Cement Degree of Conversion.

CLINICAL RELEVANCE: The use of multipeak LED light-curing guarantees efficiency on light activation of Ivocerin-containing light-cured resin cement.

Does a Self-etching Ceramic Primer Improve Bonding to Lithium Disilicate Ceramics? Bond Strengths and FESEM Analyses.

OBJECTIVE:: To compare the effect of hydrofluoric acid (HF) vs self-etching ceramic primer on resin cement microshear bond strength (µSBS) and ultramorphology of lithium disilicate (LD) ceramic. METHODS AND MATERIALS:: LD (IPS e.max CAD, Ivoclar Vivadent) blocks (14×4×2 mm3) were polished to 1200 grit and assigned to nine groups (n=5): CON: control, no LD surface treatment; IVO: 5.0% HF (IPS Ceramic Etching Gel, Ivoclar Vivadent); VIT: 5.0% HF (Vita Ceramics Etch, VITA Zahnfabrik); FGM: 5.0% HF (Condac Porcelana, FGM); ULT: 9.0% HF (Porcelain Etch, Ultradent); PRM: 9.6% HF (Premier Porcelain Etch Gel, Premier); BIS: 9.5% HF (Porcelain Etchant, Bisco Inc); DEN: 10.0% HF (Condicionador de Porcelanas, Dentsply Brazil); and MEP: self-etching ceramic primer (Monobond Etch & Prime, Ivoclar Vivadent). For all HF groups and control, an MDP-containing silane solution (MB+, Monobond Plus, Ivoclar Vivadent) was applied on rinsing the HF gel and air drying. Three transparent matrices for each specimen were filled with light-cured resin cement (Variolink Veneer, Ivoclar Vivadent). After storage in water for 48 hours at 37°C, specimens were tested in shear mode to measure µSBS. Mode of failure was analyzed at 50×. Statistical analysis included one-way analysis of variance and the Duncan post hoc test (α=0.05). Thirty-six additional LD specimens were assigned to the same experimental groups (n=4) and observed under a field-emission scanning electron microscope (FESEM) at magnifications ranging from 10,000× to 100,000×. RESULTS:: IVO resulted in statistically higher mean µSBS than all the other groups. MEP resulted in statistically lower µSBS than all HF groups. The failure mode for MEP was predominantly adhesive. The most frequent failure mode for the HF groups was mixed. CON resulted in 100% pretesting failures. For FESEM, no retentive pattern was observed for CON specimens. MEP resulted in the least pronounced etching pattern, few areas around crystals exhibited a slight increase in retention pattern compared to the control group. All HF gels created microporosities on the LD surface with distinct etching patterns. VIT and DEN resulted in an LD ultramorphology that suggested overetching. CONCLUSIONS:: HF etching followed by a silane solution resulted in higher bond strengths than a self-etching ceramic primer. Some HF gels may cause overetching of the LD intaglio surface.

Do collagen cross-linkers improve dentin's bonding receptiveness?

OBJECTIVES: Dentin biomodification using collagen cross-linkers has been proposed as one of the strategies to improve bond durability of adhesives to dentin. However, literature is not very consistent regarding their benefit, in particular when cross-linkers are applied in clinically realistic application times. This study investigated the effect of three cross-linkers on the mini-interfacial fracture toughness (mini-iFT) of four adhesives bonded to dentin following either etch&rinse (E&R) or self-etch (SE) modes. METHODS: 60 molars were randomly divided in accordance with the three variables: cross-linker, adhesive and bonding mode (n=5). The cross-linkers glutaraldehyde (5wt%; GA), proanthocyanidin (6.5wt%; PA), or UVA-activated riboflavin (0.5wt%; RB), and distilled water (control) were applied on dentin for 60s after acid-etching (E&R) or before self-etching (SE). The 3-step E&R adhesive (3E&Ra) OptiBond FL (Kerr), the 2-step SE adhesive (2SEa) Clearfil SE Bond 2 (Kuraray Noritake) and the universal adhesives G-Premio Bond (GC) and Prime&Bond Active (Dentsply), the latter two employed in both E&R and SE modes, were applied following the respective manufacturer's instructions. Composite buildups (8×8×8mm) were made using Filtek Supreme XTE (3M) prior to 1-week storage in artificial saliva. After the teeth were sectioned into mini-specimens (1.5×2.0×18mm), a single notch was prepared at the adhesive-dentin interface. Half of the specimens were immediately loaded until failure by 4-point bending to determine the mini-iFT, while the remaining specimen set was tested upon 6-month aging. Data were statistically analyzed with a linear model (p<0.05). RESULTS: No significant decrease in mini-iFT was noted only for PA (p<0.05), while the mini-iFT decreased for both other cross-linkers and in quite a similar way as when solely water (Wa) was applied. SIGNIFICANCE: The cross-linker proanthocyanidin (PA) applied in clinically relevant conditions was able to maintain a stable mini-iFT after 6-month aging. The incorporation of UVA-activated riboflavin (RB) and glutaraldehyde (GA) in the dentin-bonding protocol appeared not effective to improve the stability of adhesive-dentin interfaces.

Microshear Bond Strength of Resin Cements to Lithium Disilicate Substrates as a Function of Surface Preparation.

OBJECTIVES: To investigate the effect of hydrofluoric acid (HF) etching, silane solution, and adhesive system application on the microshear bond strength (µSBS) of lithium disilicate glass-ceramic (LD) to three resin cements. MATERIALS AND METHODS: Circular bonding areas were delimited on the lithium disilicate surfaces using a perforated adhesive tape. Specimens were assigned to 18 subgroups (n=12) according to surface treatment: NT = no treatment; HF = 4.8% HF for 20 seconds; silane solution: (1) no silane; (2) Monobond Plus, a silane/10-methacryloyloxydecyl dihydrogen phosphate solution for 60 seconds; (3) Monobond Plus+ExciTE F DSC, a dual-cure adhesive; and resin cement: (1) Variolink II, a bisphenol A diglycidyl ether dimethacrylate (bis-GMA)-based, hand-mixed, dual-cure resin cement; (2) Multilink Automix, a bis-GMA-based, auto-mixed, dual-cure resin cement; (3) RelyX Unicem 2, a self-adhesive, auto-mixed, dual-cure resin cement. Tygon tubes (Ø=0.8 mm) were used as cylinder matrices for resin cement application. After 24 hours of water storage, the specimens were submitted to the µSBS test. Mode of failure was evaluated under an optical microscope and classified as adhesive, mixed, cohesive in resin cement, or cohesive in ceramic. Data were statistically analyzed with three-way analysis of variance and Dunnett test (p<0.05). RESULTS: When means were pooled for the factor surface treatment, HF resulted in a significantly higher µSBS than did NT (p<0.0001). Regarding the use of a silane solution, the mean µSBS values obtained with Monobond Plus and Monobond Plus+ExciTE F DSC were not significantly different but were higher than those obtained with no silane (p<0.001). Considering the factor resin cement, Variolink II resulted in a significantly higher mean µSBS than did RelyX Unicem 2 (p<0.03). The mean µSBS for Multilink Automix was not significantly different from those of Variolink II and RelyX Unicem 2. According to Dunnett post hoc test (p<0.05), there was no significant difference in µSBS between the different resin cements for HF-etched and silanized (with or without adhesive application) LD surfaces. CONCLUSION: LD may benefit from pretreatment of the inner surface with HF and silanization, regardless of the resin cement used.

Desenvolvimento de Maytenus ilicifolia e de seus polifenóis totais sob condição de sombreamento e poda / Shadowing and pruning on the development and polyphenol contents in Maytenus ilicifolia

Maytenus ilicifolia Mart. ex Reissek (Celastraceae), conhecida popularmente por espinheira-santa, é nativa e cultivada, principalmente, no sul do Brasil. Suas folhas apresentam triterpenos e substâncias polifenólicas (flavonóides e taninos) relacionadas ao efeito antiulcerogênico. O objetivo do trabalho foi avaliar a produção de massa seca, altura, ramificação, e o teor de polifenóis totais em plantas de M. ilicifolia que se desenvolveram sob duas condições de luminosidade, após dois tratamentos distintos de poda. O delineamento experimental foi em blocos cazualizados com plantas desenvolvidas sob sombra e a pleno sol, e com plantas manejadas por poda parcial e rasa, com quatro repetições. No tratamento de poda rasa a maior altura das plantas foi observada nas plantas cultivadas a sombra em comparação com as conduzidas a pleno sol. No tratamento de poda parcial o número de ramos terciários aumentou significativamente nas plantas conduzidas a pleno sol. As plantas cultivadas a pleno sol apresentaram diferença significativa na concentração de polifenóis totais em relação às plantas produzidas à sombra alcançando valores de 10,29 ± 0,20% (CV=1,94%) e 7,16 ± 0,09% (CV=1,30%) respectivamente.

The Maytenus ilicifolia Mart. ex Reissek (Celastraceae), traditionally known as "espinheira-santa" in Portuguese, is native and cultivated in South Brazil. Its leaves contain triterpenes and polyphenolic compounds (flavonoids and tannins), which are related to the antiulcerogenic effect. The aim of this work was to evaluate the dried biomass production (g), height (m), ramification, and also the total content in polyphenol compounds of the leaves from the M. ilicifolia specie, which were developed under two different light conditions after two different pruning treatments. The design of the experiment was randomized blocks with two levels of light (shadow or full sunlight) and two levels of prune (partial and drastic), with four replications. The height of the plants grown in the shadow was greater for the treatment of drastic pruning than in plants in full sunlight. The ramification increased significantly with drastic prune in full sunlight. The plants grown in full sunlight showed a significant higher content in total polyphenols than the plants grown in the shadow, 10.29±0.20% (RSD=1.94%) and 7.16±0.09% (RSD=1.30%) respectively.

Tooth fragment reattachment: the natural restoration.

The aim of this manuscript was to discuss some important considerations about tooth fragment reattachment and report the success of a clinical case in which a tooth fragment and direct composite resin were used to restore a fractured anterior tooth. Clinical and radiographic examination 12 months after trauma showed good esthetics and periodontal health.

Validação de metodologia analítica para a determinação de derivados do ácido o-hidroxicinâmico de Echinodorus grandiflorus / Validation of analytical methodology for the determination of derivatives of o-hydroxycinnamic acid from Echinodorus grandiflorus

Este artigo descreve o desenvolvimento e a validação de método espectrofotométrico UV-Visível para quantificação de derivados do ácido o-hidroxicinâmico em folhas de Echinodorus grandiflorus. O método demonstrou ser linear (r² = 0,9974), preciso (DPR < 15%) na análise de matriz complexa e exata (recuperação = 107,56%).

This paper describes the development and the validation of an UV-Vis spectrophotometric method for the quantification of derivatives of o-hydroxycinnamic acid in leaves of Echinodorus grandiflorus. The method showed to be linear (r² = 0.9974), precise (RSD < 15%) in the analysis of complex matrix and accurate (recovery = 107.56%).

Novel exon nucleotide deletion causes adrenoleukodystrophy in a Brazilian family.

Adrenoleukodystrophy is a neurodegenerative X-linked recessive disorder. It is characterized by abnormal function of peroxisomes, which leads to an accumulation of very long-chain fatty acids in plasma and tissues, especially in the cortex of adrenal glands and white matter of the central nervous system, causing demyelinating disease and adrenocortical insufficiency (Addison's disease). It is caused by a mutation in the ABCD1 gene (ATP-binding cassette, subfamily D, member 1), which encodes the protein adrenoleukodystrophy that is involved in the transport of fatty acids into the peroxisome for degradation. Variable expression has been recognized in families of patients who have this disease. A Brazilian family from Minas Gerais State, Brazil, was studied. The proband is an adult living in Minas Gerais State, Brazil; he had adrenomyeloneuropathy, adrenocortical insufficiency and a stable cerebral form. DNA was extracted from a blood sample and was sequenced to identify the mutation. The patient's exons were cloned for confirmation. A new mutation was found in exon 5 of the ABCD1 gene (c.1430delA), as well as a single-nucleotide polymorphism in exon 6. The mutation causes a frame shift, resulting in a truncated protein with almost total absence of the ATP binding domain.

A 2-year evaluation of moisture on microtensile bond strength and nanoleakage.

OBJECTIVES: This study evaluated the effect of moisture on the resin-dentin mu-bond strength (BS) and silver nitrate uptake (SNU) of three adhesive systems (Single Bond, One-Step and Syntac Single Component) soon after bonding (IM) and after 2 years of water storage (2Y). METHODS: Dentin surfaces were bonded on a dry (D), moist (W) or over-wet surfaces (OW). After restorations were constructed, specimens were stored in water (37 degrees C/24h). Resin-dentin sticks were prepared (0.8mm(2)) and they were divided for immediate (IM) and 2-year storage (2Y) testing. Half of the specimens from each period of time were tested in tension at 0.5mm/min and the other half was immersed in silver nitrate and examined by SEM-EDX. The data was analyzed by three-way repeated measures ANOVA and Tukey's tests (alpha=0.05). RESULTS: The overall BS (MPa) in the IM group under W condition was higher than in D and OW groups. After 2Y, the BS in W was lower than in the IM group, however higher than in the D and OW for OS and SB. The overall silver nitrate deposition (%) in the IM group under D, W and OW were similar. In the 2Y groups, the nanoleakage was higher than IM groups, however the increase was less pronounced in the W condition. SIGNIFICANCE: Higher BS and a significantly lower nitrate uptake were observed for IM groups, for OS and SB. Under W conditions, the BS reduction over time was less pronounced and less nitrate uptake occurred.

Estudo físico-químico, químico e biológico de extrato das cascas de Stryphnodendron polyphyllum Mart. (Leguminosae)

Two flavan-3-ols and one proanthocyanidins have been isolated from the stem bark of Stryphnodendron polyphyllum Mart., which is traditionally used in Brazil against various diseases. The structure was determined on the basis of spectroscopic data including 1-D (¹H, 13C) and 2-D NMR (¹H/¹H COSY) and MS. The antibacterial activities of an acetone:water and semipurified extracts from the stem bark of Stryphnodendron polyphyllum Mart. were evaluated. Both the crude and semipurified extracts showed activity against Bacillus subtilis and Staphylococcus aureus. Quality control was determined using several pharmacopoeial assay.

All-ceramic post core, and crown: technique and case report.

UNLABELLED: The functional and esthetic restoration of severely compromised anterior teeth is a challenge to clinicians in their daily practice. The duplication of the optical characteristics of an intact tooth, including shade, translucency, and fluorescence, is often made difficult by the use of metal infrastructures, such as post-and-cores and copings. The development of reinforced ceramics and non-metallic post systems made possible the generation of metal-free ceramic restorations in severely compromised anterior and posterior teeth. This article discusses one available technique for the generation of a single all-ceramic restoration involving the use of a zirconia- or leucite-reinforced post-and-core system and of an all-ceramic crown system. A representative clinical case is presented illustrating the potential of the technique. CLINICAL SIGNIFICANCE: Modern ceramic restorative systems offer the possibility to closely match the natural optical characteristics of lost tooth structure. Posts, cores, and copings fabricated in ceramic materials represent a promising alternative to metals in the restoration of severely compromised anterior teeth.

Effect of a sodium hypochlorite gel on dentin bonding.

UNLABELLED: It has been suggested that the hybrid layer (HL) does not play any important role in the mechanism of adhesion to dentin. To substantiate this hypothetical insignificance of the HL, sodium hypochlorite (NaOCl) has been used to remove collagen from etched dentin prior to bonding. OBJECTIVES: The present study was conducted to determine the effect of a commercial 10% NaOCl gel on the dentin shear bond strengths and HL ultra-morphology of two simplified dentin adhesives. The null hypothesis tested was that treatment of etched dentin collagen with NaOCl would not compromise dentin bonding. METHODS: The labial surface of eighty bovine incisors was polished to expose middle dentin. The specimens were randomly assigned to two total-etch adhesive systems (N = 40): Prime&Bond NT (Dentsply Caulk); and Single Bond (3M Dental Products Division). After rinsing off the etchant, one drop of 10% NaOCl (AD Gel, Kuraray Ltd.) was applied to the etched dentin surface and left for 0 (control), 15, 30, or 60 s. The gel was rinsed off with water and the dentin surface kept visibly moist prior to the application of the adhesive as per manufacturer's instructions. The respective composite resin was subsequently applied and light-cured. After 24 h in water at 37 degrees C, the specimens were thermocycled for 500 cycles in baths kept at 5 and 55 degrees C and the shear bond strengths measured. The data were analyzed with two-way ANOVA. For TEM, sixteen dentin disks were taken from middle dentin of extracted human third molars, assigned to the eight treatment sequences, and observed. RESULTS: The increase in the NaOCl application time resulted in a progressive decrease in shear bond strengths for both dentin adhesives. For Single Bond, the application of AD Gel for 60 s resulted in a reduction of bond strengths to 38% of that obtained for the control. For Prime&Bond NT, the mean bond strength obtained when AD Gel was applied for 60 s was 31% of that obtained for the control. The application of AD Gel resulted in distinct morphology for each one of the two adhesives tested. For Single Bond, the general morphology of the collagen network was maintained, regardless of the deproteinization time. The interfibrillar space within the collagen network increased with increasing deproteinization times. For Prime&Bond NT, the general appearance of the HL was maintained for deproteinization times of 15 and 30 s. When the NaOCl gel was applied for 60 s, the morphological appearance of the HL lost its fibrillar arrangement. While remnants of the collagen fibers were observed in one of the dentin disks, the other specimen showed an amorphous structure without any discernible HL morphological features. SIGNIFICANCE: The integrity of the collagen fibrils left exposed upon acid-etching plays a major role in the mechanism of adhesion of the specific adhesive systems tested in this study. The intermingling of the adhesive monomers with the filigree of collagen fibers or HL should still be considered the paramount dentin bonding mechanism.

Bond strengths of new simplified dentin-enamel adhesives.

PURPOSE: To compare the in vitro shear bond strengths (SBS) of five simplified dentin adhesives. The tested hypothesis was that the recently introduced simplified adhesive systems would have similar or higher SBS than an existing simplified acetone-based adhesive used as a control. MATERIALS AND METHODS: 100 flat bonding sites were polished to 600-grit on the labial surface of bovine incisors mounted in acrylic resin. 50 teeth were ground to expose enamel, while the remaining 50 specimens were prepared to expose middle dentin. The specimens were randomly divided into five equal groups to be treated with simplified dentin adhesives: Dentastic Uno, EasyBond, Gluma One Bond, One Coat Bond, and One-Step (control). A composite post was bonded to each treatment area. After thermo-cycling, enamel and dentin shear bond strengths were determined using an Instron testing machine and the data were submitted to statistical analyses. RESULTS: Mean enamel bond strengths ranged from 14.6-28.4 MPa. One Coat Bond had the highest mean enamel SBS, but it was not significantly higher than those of Gluma One Bond and Dentastic Uno. EasyBond and One-Step had statistically similar mean enamel SBS and these were significantly lower than the mean enamel SBS of the other three adhesives. For dentin, mean SBS ranged from 14.8-21.7 MPa. Dentastic Uno had the highest mean dentin SBS, but it was not significantly greater than those of One Coat Bond and Gluma One Bond. Although One Step had the lowest mean dentin SBS, it was not significantly different from those of either EasyBond or Gluma One Bond.

Effects of repeated use on bond strengths of one-bottle adhesives.

OBJECTIVE: Most one-bottle adhesives contain organic solvents (acetone or ethanol) that displace the water entrapped within the network of collagen fibers in etched dentin. Acetone and ethanol are volatile substances that could easily evaporate from bottles during use. The objective of this in vitro study was to assess the effects of repeated opening of bottles on dentin shear bond strengths of 4 adhesives. METHOD AND MATERIALS: Eighty freshly extracted bovine incisors were mounted, polished to 600 grit, and randomly assigned to 8 groups (n = 10). After the application of the materials to 40 specimens at baseline, adhesive use was simulated by opening bottles for 1 minute, 2 times a day, for 3 weeks, except during weekends, when the bottles were kept refrigerated. After 3 weeks of simulated use, the same adhesives were applied to 40 additional specimens. Resin composite was applied to dentin in a No. 5 gelatin capsule and was light-cured. After 500 thermal cycles (5 degrees C to 55 degrees C), shear bond strength testing was performed with a universal testing machine at 0.5 cm/min. RESULTS: Adhesives containing ethanol or water had similar mean bond strengths at baseline and at 3 weeks. The acetone-based material had a significantly lower mean bond strength at 3 weeks than at baseline. CONCLUSION: Acetone-based adhesives may have a shorter useful life than ethanol- and water-based adhesives.

Avaliaçäo do conhecimento sobre doenças sexualmente transmissíveis (DSTs) e síndrome da imunodeficiência adquirida (AIDS) entre universitários de Ribeiräo Preto/SP / Evaluation of the knowledge on sexually transmitted diseases (STDs) and acquired immunodeficiency syndrome (AIDS) among universitary students of Ribeiräo Preto/SP

Com o objetivo de avaliar o grau de conhecimento sobre DST/AIDS entre universitários de diferentes áreas, submeteu estudantes de uma faculdade de Ribeiräo Preto-SP a questionários com perguntas abertas e fechadas, anônimos após aquiescência. As respostas foram categorizadas como corretas (C), incorretas (I), entendimento incompleto (EI) e prejudicadas (P), sendo a análise realizada por porcentagens. De 1.200 estudantes, 961 (80,80 por cento) participaram do estudo. O número de respostas näo foi harmonioso para os diferentes itens do questionário. A área em que o aluno estava matriculado näo pareceu influenciar nas respostas. Com relaçäo à transmissäo do HIV, em 2.914 respostas obteve-se 65,37 por cento como categoria EI e em 923 (31,68 por cento) como C. Quanto a medidas preventivas contra a AIDS de 1888 respostas, 1.625 (86,07 por cento) como categoria C e 207 (10,96 por cento) como EI. Sobre medidas preventivas contra AIDS, utilizadas pelo aluno, 1.126 (74,42 por cento) como categoria C e 249 (16,46 por cento) e P. Quanto a medidas preventivas contra DSTs, 1.339 (71,11 por cento) como categoria C e 284 (15,80 por cento) obteve-se 1. Sobre medidas preventivas contra DSTs utilizadas pelo aluno, obteve-se 542 (43,92 por cento) como categoria C e 350 (28,36 por cento) como P. Os universitários em sua maioria parecem possuir um conhecimento teórico correto sobre as medidas preventivas contra à AIDS e DST e entendimento incompleto sobre a transmissäo do HIV. Provavelmente existem fatores relacionados à educaçäo ou culturais que impedem aos universitários fazerem uso das medidas preventivas que conhecem. Há necessidade de identificaçao desses fatores para que os programas de difusäo possam atingir os seus objetivos. A educaçäo continuada ainda se mostra necessária.