Brachytherapy versus radical hysterectomy after external beam chemoradiation with gemcitabine plus cisplatin: a randomized, phase III study in IB2-IIB cervical cancer patients.

BACKGROUND: The aim of the present study was to demonstrate that radical hysterectomy (RH) leads to improved survival outcomes in FIGO stage IB2-IIB cervical cancer when compared with standard brachytherapy (BCT) after identical external beam chemoradiation (EBRT-CT). PATIENTS AND METHODS: EBRT-CT treatment consisted of six courses of cisplatin at 40 mg/m² and gemcitabine at 125 mg/m² per week concurrent with 50.4 Gy of radiation. In the BCT arm, EBRT-CT was followed by BCT to reach a point A dose of 85 Gy, whereas in the experimental arm, a type III RH with bilateral pelvic lymph node dissection and para-aortic lymph node sampling (RH) was carried out within 4-6 weeks after EBRT-CT. RESULTS: Between May 2004 and June 2009, 211 patients were enrolled (BCT, 100 and RH, 111). At a median follow-up time of 36 months (3-80), progression-free survival (PFS) and overall survival (OS) rates were similar in both the arms. PFS rates were 74.8% and 71.7% in the BCT and RH arms [HR 0.6516 (95% confidence interval (CI) 0.3504-1.2116)], P = 0.186. OS rates were 76.3% in the BCT versus 74.5% in the surgical arm [HR 0.6981 (95% CI 0.3106-1.3439)], P = 0.236. No differences were observed in the pattern of local and systemic failures. CONCLUSIONS: This study failed to demonstrate that RH after EBRT-CT is superior to standard BCT.

Origin of interfacial droplets with one-step adhesives.

Contemporary one-step self-etch adhesives are often documented with interfacial droplets. The objective of this study was to research the origin of these droplets. Two HEMA-rich and one HEMA-free adhesive were applied to enamel and dentin, with the lining composite either immediately cured or cured only after 20 min. All one-step adhesives exhibited droplets at the interface; however, the droplets had two different origins. With the HEMA-free adhesives, droplets were located throughout the adhesive layer and were stable in number over time. With the HEMA-rich adhesives, the droplets were observed exclusively at the adhesive resin/composite interface, and their number increased significantly when the composite was delay-cured. Only the latter droplets caused a significant drop in bond strength after delayed curing. While the droplets in the HEMA-free one-step adhesives should be ascribed to phase separation, those observed with HEMA-rich adhesives resulted from water absorption from dentin through osmosis.

Effects of ceramic surface treatments on the bond strength of an adhesive luting agent to CAD-CAM ceramic.

OBJECTIVES: The objective of this study was to evaluate the effect of different surface treatments on the micro-tensile bond strength (microTBS) of an adhesive luting agent to CAD-CAM ceramic. The hypothesis tested was that neither of the surface treatments would produce higher bond strength of the adhesive luting agent to CAD-CAM ceramic. METHODS: Ceramic specimens of two different sizes (6 mm x 8 mm x 3 mm; 13 mm x 8 mm x 4 mm) were fabricated from ProCAD ceramic blocs (Ivoclar-Vivadent) with a low-speed diamond saw. The ceramic blocks were divided into seven groups and submitted to the following surface treatments: group 1: no treatment; group 2: etching with 37% H(3)PO(4); group 3: etching with 37% H(3)PO(4)+silane; group 4: etching with 37% H(3)PO(4)+silane+adhesive resin; group 5: etching with 4.9% HF acid; group 6: etching with 4.9% HF acid+silane; group 7: etching with HF acid+silane+adhesive resin. After surface treatment, two differently sized porcelain disks were bonded together with a composite luting agent (Variolink II, Ivoclar-Vivadent). The specimens were stored for 24h in distilled water at 37 degrees C prior to microTBS testing. One-way analysis of variance was used to test the influence of surface treatment and Scheffe multiple comparisons test determined pair-wise statistical differences (p<0.05) in microTBS between the experimental groups. RESULTS: The mean microTBSs (standard deviation) are: group 1: 12.8 (+/-4.6)MPa; group 2: 19.1 (+/-5.0)MPa; group 3: 27.4 (+/-11.1)MPa; group 4: 34.0 (+/-8.9)MPa; group 5: 37.6 (+/-8.4) MPa; group 6: 34.6 (+/-12.8)MPa; group 7: 34.5 (+/-5.1)MPa. Statistical significant differences were found between group 1 and groups 3-7, and between group 2 and groups 4-7. All specimens of groups 1-4 exhibited adhesive failures, while a combination of adhesive and mixed (adhesive and cohesive) failures was observed in the specimens of groups 5-7. CONCLUSIONS: The results show that surface treatment is important to bond to ceramic and suggests that etching is needed preferably with hydrofluoric acid than with phosphoric acid.

Bond durability of composite luting agents to ceramic when exposed to long-term thermocycling.

PURPOSE: This study evaluated the effect of thermocycling on the microtensile bond strength of four adhesive luting agents to GN-I CAD-CAM ceramic. The hypothesis tested was that thermocycling did not affect bonding effectiveness, irrespective of the luting agents used. MATERIALS AND METHODS: Ceramic specimens of two different sizes (6x8x3 mm; 13x8x4 nm) were fabricated from GN-I CAD-CAM ceramic blocks (GC) using a low-speed diamond saw. Two different sized porcelain discs were bonded with one of the four composite luting agents (Linkmax [LM], Panavia [PN], RelyX Unicem [UN] and Variolink II [VL]) according to the manufacturer's instructions. The specimens were stored for 24 hours in distilled water at 37 degrees C and subjected to 0; 10,000; 20,000 and 40,000 thermocycles prior to microTBS testing. Two-way analysis of variance was used to test the influence of luting cement, thermocycling and interaction between both (p < 0.05). The Tukey HSD test determined statistical differences in microTBS for each luting composite between the different thermocycling conditions (p < 0.05). The mode of failure was determined at a magnification of 50x using a stereomicroscope (Wild M5A). RESULTS: Two-way ANOVA revealed that microtensile bond strength was affected by the luting cement, thermocycling and a combination of both. No difference in bond strength between Linkmax, Panavia F and Variolink II was noticed after 24 hours of water storage (LM: 47.6 MPa; PN: 41 MPa; VL: 36 MPa). RelyX Unicem scored significantly lower than Linkmax and Panavia F (UN: 24.2 MPa). The influence of thermocycling on bond strength was different for the four luting cements. Using Variolink II, the bond strength remained stable after 40,000 thermocycles (43.6 MPa). Linkmax showed a significant decrease in bond strength after 10,000 (26 MPa) and 40,000 thermocycles (14.8 MPa). Panavia F and RelyX Unicem were the most negatively influenced, as all specimens failed prior to testing (pre-testing failures) when the specimens were thermocycled 10,000 and 20,000 times or longer, respectively. Regarding the failure mode, there was a correlation between bond strength and type of failure. Initially, a combination of adhesive and mixed adhesive-cohesive failures was noticed. The percentage of adhesive failures increased, together with a decrease in bond strength. CONCLUSION: It was concluded that there were significant differences among the four resin composite cements in terms of their bonding effectiveness to CAD-CAM ceramic after thermocycling. The varying degrees of bonding effectiveness of these adhesive luting agents highlight the need for material specifications.

Development of a self-etch adhesive for resin-modified glass ionomers.

The favorable self-adhesiveness of resin-modified glass ionomers (RMGIs) might be even further improved if the time-consuming and technically sensitive etch-and-rinse pre-treatment step with polyalkenoic acids could be avoided. We undertook this study to assess the effectiveness of an experimental self-etch adhesive for RMGIs that does not need to be rinsed off. Ultrastructural analysis and micro-tensile bond strength testing to enamel and dentin of a RMGI restorative material and a RMGI adhesive were performed after 4 different surface pre-treatments: no conditioning; 25% polyalkenoic acid; an experimental self-etch adhesive; and 37.5% phosphoric acid followed by the experimental self-etch adhesive. The use of an experimental self-etch adhesive increased the bond strength of RMGIs, especially after an additional conditioning step. Interfacial analysis showed the formation of a thin hydroxyapatite-containing hybrid layer. The self-etch technique enhances the user-friendliness of RMGIs and lowers their technique-sensitivity, while maintaining desirable characteristics of the conventional etch-and-rinse approach with polyalkenoic acids.

A critical review of the durability of adhesion to tooth tissue: methods and results.

The immediate bonding effectiveness of contemporary adhesives is quite favorable, regardless of the approach used. In the long term, the bonding effectiveness of some adhesives drops dramatically, whereas the bond strengths of other adhesives are more stable. This review examines the fundamental processes that cause the adhesion of biomaterials to enamel and dentin to degrade with time. Non-carious class V clinical trials remain the ultimate test method for the assessment of bonding effectiveness, but in addition to being high-cost, they are time- and labor-consuming, and they provide little information on the true cause of clinical failure. Therefore, several laboratory protocols were developed to predict bond durability. This paper critically appraises methodologies that focus on chemical degradation patterns of hydrolysis and elution of interface components, as well as mechanically oriented test set-ups, such as fatigue and fracture toughness measurements. A correlation of in vitro and in vivo data revealed that, currently, the most validated method to assess adhesion durability involves aging of micro-specimens of biomaterials bonded to either enamel or dentin. After about 3 months, all classes of adhesives exhibited mechanical and morphological evidence of degradation that resembles in vivo aging effects. A comparison of contemporary adhesives revealed that the three-step etch-and-rinse adhesives remain the 'gold standard' in terms of durability. Any kind of simplification in the clinical application procedure results in loss of bonding effectiveness. Only the two-step self-etch adhesives approach the gold standard and do have some additional clinical benefits.

Monomer-solvent phase separation in one-step self-etch adhesives.

One-step adhesives bond less effectively to enamel/dentin than do their multi-step versions. To investigate whether this might be due to phase separation between adhesive ingredients, we characterized the interaction of 5 experimental and 3 commercial self-etch adhesives with dentin using transmission electron microscopy. All adhesives were examined for homogeneity by light microscopy. Bonding effectiveness to dentin was determined with the use of a micro-tensile bond-strength protocol. The lower bond strength of the one-step adhesives was associated with light-microscopic observation of multiple droplets that disappeared slowly. Interfacial analysis confirmed the entrapment of droplets within the adhesive layer. The prompt disappearance of droplets upon application of a small amount of HEMA (2-hydroxyethyl methacrylate) or a HEMA-containing bonding agent, as well as the absence of droplets at the interface of all HEMA-containing adhesives, strongly suggests that the adhesive monomers separate from water upon evaporation of ethanol/acetone. Upon polymerization, the droplets become entrapped within the adhesive, potentially jeopardizing bond durability. This can be avoided by strong air-drying of the adhesive, thereby removing interfacial water and thus improving bonding effectiveness.

Bonding of low-shrinking composites in high C-factor cavities.

OBJECTIVES: Polymerization shrinkage causes stress at the tooth-restoration interface. The magnitude of the stress depends upon several factors, such as the configuration factor (C-factor) of the cavity, the polymerization-conversion rate and filling technique. The aim of this study was to investigate the effect of curing time and filling method when high C-factor cavities were filled with low-shrinking composites. METHODS: Three low-shrinking (Filtek Silorane, 3M ESPE: FS; N'Durance, Septodont: N'D; Kalore, GC: Ka) and one conventional composite (Z100, 3M ESPE) were bonded into standardized occlusal Class-I cavities using either a two-step self-etch adhesive (Silorane System Adhesive, 3M ESPE: SSA) or a one-step self-etch adhesive (G-Bond, GC: GB). Five experimental groups were formed according to the employed adhesive/composite combination (SSA/FS, SSA/Z100, GB/N'D, GB/Ka, GB/Z100), and further divided into three subgroups conforming to curing time and filling technique (20 s/bulk; 80 s/bulk; 80 s/layered). For each subgroup, non-trimmed 1 mm×1 mm sticks were prepared from five teeth to measure the micro-tensile bond strength (µTBS) to cavity-bottom dentine. RESULTS: The two-step self-etch adhesive SSA generated higher bond strengths than the one-step self-etch adhesive GB, irrespective of the filling method. When GB was used, bulk filling with a low-shrinking composite revealed the highest bond strengths. For all composites, the layering method provided the highest bond strengths. SIGNIFICANCE: The two-step self-etch adhesive Silorane System Adhesive (3M ESPE) performed better than the one-step self-etch adhesive G-Bond (GC), regardless of the composite used. When the latter all-in-one adhesive was used, effects of shrinkage stress became more apparent.

Meta-analytical review of parameters involved in dentin bonding.

Bond-strength testing is the method most used for the assessment of bonding effectiveness to enamel and dentin. We aimed to disclose general trends in adhesive performance by collecting dentin bond-strength data systematically. The PubMed and EMBASE databases were used to identify 2,157 bond-strength tests in 298 papers. Most used was the micro-tensile test, which appeared to have a larger discriminative power than the traditional macro-shear test. Because of the huge variability in dentin bond-strength data and the high number of co-variables, a neural network statistical model was constructed. Variables like 'research group' and 'adhesive brand' appeared most determining. Weighted means derived from this analysis confirmed the high sensitivity of current adhesive approaches (especially of all-in-one adhesives) to long-term water-storage and substrate variability.

Relationship between bond-strength tests and clinical outcomes.

One often alleges that laboratory bond-strength testing cannot predict clinical effectiveness of adhesives. Major argument to sustain this claim is the wide variation in bond-strength values recorded for one specific adhesive among different research institutes worldwide. The main reason for these inconsistent bond-strength measurements is supposedly the current lack of a standard bond-strength testing protocol. This paper (and presentation) aimed to report on an extensive literature review with regard to the different laboratory bond-strength test methods and their data provided, along with a second extensive literature review on clinical effectiveness data of adhesives in terms of retention rates of adhesive Class-V restorations. Combining both systematic reviews, we have subsequently searched for a potential relationship between bond-strength data and clinical outcomes.

Eight-year clinical evaluation of a 2-step self-etch adhesive with and without selective enamel etching.

OBJECTIVES: The objective of this randomized controlled clinical trial was to evaluate the 8-year clinical performance of a mild 2-step self-etch adhesive in non-carious Class-V lesions with and without prior selective phosphoric acid-etching of the enamel cavity margins. METHODS: A total of 100 non-carious Class-V lesions in 29 patients were restored with Clearfil AP-X (Kuraray). The composite restorations were bonded following two different approaches: (1) application of Clearfil SE (Kuraray) following a self-etch approach (control group; C-SE non-etch), (2) selective phosphoric acid-etching of the enamel cavity margins before application of Clearfil SE (experimental group; C-SE etch). The restorations were evaluated after 6 months, 1, 2, 3, 5 and 8 years of clinical service regarding their retention, marginal integrity and discoloration, caries occurrence, preservation of tooth vitality and post-operative sensitivity. RESULTS: The recall rate at 8 years was 76%. Only two restorations, one of the C-SE non-etch group and one of the C-SE etch group, were clinically unacceptable due to loss of retention leading to a retention rate and a clinical success rate of 97% in both groups. Aging of the restorations was characterized by an increase in the percentage of restorations with a small but clinically acceptable marginal defect (C-SE non-etch: 92%; C-SE etch: 84%) and/or a superficial marginal discoloration (C-SE non-etch: 44%; C-SE etch: 28%). At the enamel side, the presence of small marginal defects (C-SE non-etch: 86%; C-SE etch: 65%) and superficial marginal discoloration (C-SE non-etch: 11%; C-SE etch%) was more frequently noticed in the control group than in the experimental group. The difference, however, was only statistically significant for the presence of superficial marginal discoloration (McNemar, p=0.01). SIGNIFICANCE: After 8 years of clinical functioning, the clinical effectiveness of Clearfil SE remained excellent, with selective acid-etching of the enamel cavity margins only having some minor positive effect on marginal integrity and absence of marginal discoloration at enamel.

Enamel-smear compromises bonding by mild self-etch adhesives.

In light of the increased popularity of less acidic, so-called 'ultra-mild' self-etch adhesives, adhesion to enamel is becoming more critical. It is hypothesized that this compromised enamel bonding should, to a certain extent, be attributed to interference of bur debris smeared across enamel during cavity preparation. High-resolution transmission electron microscopy revealed that the enamel smear layer differed not only in thickness, but also in crystal density and size, depending on the surface-preparation method used. Lab-demineralization of sections clearly disclosed that resin-infiltration of an ultra-mild self-etch adhesive progressed preferentially along micro-cracks that were abundantly present at and underneath the bur-cut enamel surface. The surface-preparation method significantly affected the nature of the smear layer and the interaction with the ultra-mild adhesive, being more uniform and dense for a lab-SiC-prepared surface vs. a clinically relevant bur-prepared surface.

Inhibition of enzymatic degradation of adhesive-dentin interfaces.

Adhesive procedures activate dentin-associated matrix metalloproteinases (MMPs), and so iatrogenically initiate bond degradation. We hypothesized that adding MMP inhibitors to adhesive primers may prevent this endogenous enzymatic degradation, thereby improving bond durability. A non-specific MMP inhibitor (chlorhexidine) and a MMP-2/9-specific inhibitor (SB-3CT) were admixed to the primers of an etch & rinse and a self-etch adhesive, both considered as gold-standard adhesives within their respective categories. For dentin powder exposed to the adhesives under clinical application conditions, gelatin zymography revealed the release of MMP-2 (not of MMP-9) by the etch & rinse adhesive, while no release of enzymes could be detected for the mild self-etch adhesive, most likely because of its limited dentin demineralization effect. The built-in MMP inhibitors appeared effective in reducing bond degradation only for the etch & rinse adhesive, and not for the self-etch adhesive. Water sorption of adhesive interfaces most likely remains the principal mechanism of bond degradation, while endogenous enzymes appear to contribute to bond degradation of only etch & rinse adhesives.

Bonding effectiveness and interfacial characterization of a nano-filled resin-modified glass-ionomer.

UNLABELLED: Glass-ionomers (GIs) exhibit excellent clinical bonding effectiveness, but still have shortcomings such as polishability and general aesthetics. The aims of this study were (1) to determine the micro-tensile bond strength (microTBS) to enamel and dentin of a nano-filled resin-modified GI (nano-RMGI; Ketac N100, 3M-ESPE), and (2) to characterize its interfacial interaction with enamel and dentin using transmission electron microscopy (TEM). METHODS: The nano-RMGI was used both with and without its primer, while a conventional RMGI restorative material (conv-RMGI; Fuji II LC, GC) and a packable conventional GI cement (conv-GI; Fuji IX GP, GC) were used as controls. After bonding to freshly extracted human third molars, microspecimens of the interfaces were machined into a cylindrical hourglass shape and tested to failure in tension. Non-demineralized TEM sections were prepared and examined from additional teeth. RESULTS: The microTBS to both enamel and dentin of nano-RMGI and conv-GI were not statistically different; the microTBS of non-primed nano-RMGI was significantly lower, while that of conv-RMGI was significantly higher than that of all other groups. TEM of nano-RMGI disclosed a tight interface at enamel and dentin without surface demineralization and hybrid-layer formation. A thin filler-free zone (<1 microm) was formed at dentin. A high filler loading and effective filler distribution were also evident, with localized areas exhibiting nano-filler clustering. CONCLUSIONS: The nano-RMGI bonded as effectively to enamel and dentin as conv-GI, but bonded less effectively than conv-RMGI. Its bonding mechanism should be attributed to micro-mechanical interlocking provided by the surface roughness, most likely combined with chemical interaction through its acrylic/itaconic acid copolymers.