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.

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.

SUMMARY

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.

Capillary Electrophoresis as Tool for Diastereomeric Separation in a Trichilia catigua Fraction

INTRODUCTION

The tree Trichilia catigua, popularly known as "catuaba", shows several biological activities and has emerged as a potential source of new drugs. Considering that more than 10 species are known under the same popular name, regulatory agencies require more rigorous quality control of this medicinal plant.

OBJECTIVE

To develop and validate a methodology using capillary electrophoresis (CE) with ultraviolet (UV) detection for analysing polyphenols in the ethyl-acetate fraction (EAF) of Trichilia catigua.

METHODOLOGY

Different electrophoretic conditions (such as wavelength of UV detection, voltage, buffer concentration and pH, cyclodextrin type and concentration) were investigated. After optimisation, borate buffer 80 mmol/L at pH 8.80 with 2-hydroxypropyl-β-cyclodextrin 10 mmol/L was selected as background electrolyte. A voltage reduction was used to improve the separation of a diastereomeric pair of cinchonains.

RESULTS

The method proved to be simple, sensitive, accurate, linear, precise and reproducible. For the first time in natural products analysis, a voltage reduction and hydroxypropyl-β-cyclodextrin were used to improve the separation of diastereomeric pairs. Until now, this is the only described methodology able to separate catechin, epicatechin, cinchonains Ia, Ib, IIa, and IIb from Trichilia catigua samples on the same run in less than 12 min. When compared to the high performance liquid chromatography with photo-diode array detection (HPLC-PDA) method previously developed by our research group, the CE method was more efficient, faster, less expensive and less polluting.

CONCLUSION

Our results demonstrate that this method could be employed in a quality-control laboratory for the quantification of polyphenols in EAF of Trichilia catigua. Copyright © 2016 John Wiley & Sons, Ltd.

Avaliação da Atividade Antisséptica de Sabonete Líquido Contendo Extrato Glicólico de Flores de Tagetes patula L

Tagetes patula L. (Asteraceae), popularmente conhecida como cravo de defunto ou cravo francês, é utilizada na medicina popular como antisséptica, depurativa do sangue e repelente de insetos. O presente estudo avaliou a atividade antisséptica de sabonete líquido contendo extrato glicólico de T. patula 7,5% (p/v). O extrato glicólico foi obtido por turbo-extração utilizando propilenoglicol e etanol (7:3; v/v) a 10 % (p/v). A avaliação fitoquímica preliminar da droga vegetal indicou a presença de compostos fenólicos e teor de flavonoides de 5,73% ± 0,19 (CV = 3,33%). No teste para avaliação da atividade antimicrobiana houve a inibição do crescimento de Staphylococcus aureus na concentração de avaliada.

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.

Application and analysis of the folin ciocalteu method for the determination of the total phenolic content from Limonium brasiliense L

Limonium brasiliense is a common plant on the southern coast of Brazil. The roots are traditionally used for treatment of premenstrual syndrome, menstrual disturbances and genito-urinary infections. Pharmaceutical preparations obtained from its roots and used for these purposes were marketed in Brazil in the 1980s and 1990s. Currently, the Brazilian Drug Agency (National Health Surveillance Agency, ANVISA) has canceled the registration of these products, and their use was discontinued because of a lack of studies to characterize the plant raw material and ensure the effectiveness and safety of its use. The aim of the present study was to develop and validate an analytical method to determine the content of total polyphenols (TP) in an extract from L. brasiliense roots, by the UV/Vis spectrophotometric method. L. brasiliense roots were extracted in acetone:water (7:3, v/v-10% w/v). The crude extract was used to develop a method for TP assay. The method was validated according to national and international guidelines. The optimum conditions for analysis time, wavelength, and standard substance were 30 min, 760 nm, and pyrogallol, respectively. Under these conditions, validation by UV/Vis spectrophotometry proved the method to be linear, specific, precise, accurate, reproducible, robust, and easy to perform. This methodology complies with the requirements for analytical application and to ensure the reliability of the results.

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.

Antiviral effect of Guazuma ulmifolia and Stryphnodendron adstringens on poliovirus and bovine herpesvirus

Crude extract (CE) and aqueous (AqF) and ethyl acetate (EtOAcF) fractions of Guazuma ulmifolia Lam., Sterculiaceae and the corresponding AqF, EtOAcF of Stryphnodendron adstringens (Mart.) Coville, Leguminosae were tested for their antiviral activity against poliovirus 1 (P-1) and bovine herpesvirus 1 (BHV-1) in HEp-2 cultured cells. The antiviral activity was monitored by plaque assay and immunofluorescence assay (IFA) under virucidal and therapeutic protocols. The therapeutic protocol demonstrated statistically significant positive results with both plants and for both virus strains. The highest percentages of viral inhibition were found for G. ulmifolia EtOAcF which inhibited BHV-1 and P-1 replication by 100% and 99%, respectively (p<0.05, Student's t-test). For S. adstringens, AqF was the most efficient, inhibiting BHV-1 and P-1 by 97% and 93%, respectively (p<0.05). In the virucidal protocol, G. ulmifolia CE inhibited the replication of BHV-1 and P-1 by 60% and 26%, respectively (p<0.05), while, for S. adstringens, inhibition of 62% (p<0.05) was demonstrated only with EtOAcF for P-1. IFA demonstrated that the greatest reduction in fluorescent cell number occurred with G. ulmifolia, under the therapeutic protocol for both virus strains. However, AqF and EtOAcF of S. adstringens were most efficient with the virucidal protocol for P-1. In conclusion, we demonstrated that G. ulmifolia and S. adstringens inhibited BHV-1 and P-1 replication, as well as, blocked the synthesis of viral antigens in infected cell cultures.

Determinação quantitativa de taninos em três espécies de Stryphnodendron por cromatografia líquida de alta eficiência

Um método de separação e quantificação por cromatografia líquida de alta eficiência (CLAE) em fase reversa foi desenvolvido usando água (0,05% de TFA):acetonitrila (0,05% de TFA) como fase móvel, em sistema gradiente para a análise dos flavan-3-óis presentes em extrato semipurificado das cascas de Stryphnodendron adstringens, Stryphnodendron polyphyllum e Stryphnodendron obovatum. A CLAE foi realizada com a fração acetato de etila (FAE) sendo submetida à extração em fase sólida (cartucho C18-E) com metanol:água (2:8), filtrada por membrana de porosidade 0,5 μm; a pré-coluna e coluna empregadas foram Phenomenex® Gemini C-18 (5 μm), com esta última mantida a 30 ºC, com vazão de 0,8 mL/min e detecção a 210 nm. Utilizaram-se soluções dos padrões de ácido gálico e galocatequina para a obtenção da curva analítica. O método proposto foi validado de acordo com a resolução RE n° 899/2003 da ANVISA. A análise quantitativa da FAE das três espécies mostrou que existe similaridade no teor de galocatequina. S. adstringens possui ácido gálico em uma proporção superior a 60% em relação às outras duas espécies. A metodologia desenvolvida mostrou-se viável à aplicação em plantas ricas em taninos, como nos casos de S. adstringens, S. polyphyllum e S. obovatum.

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.

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

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

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.