GPDM- and 10-MDP-based Self-etch Adhesives Bonded to Bur-cut and Uncut Enamel - "Immediate" and "Aged" µTBS.

PURPOSE: To determine the microtensile bond strength (µTBS) of two 2-step self-etch adhesives (SEAs) to bur-cut and uncut enamel. MATERIALS AND METHODS: The buccal and lingual enamel surfaces of 15 teeth were ground flat ("bur-cut" enamel), while the enamel surface of another set of 15 teeth was solely prophylactically cleaned ("uncut" enamel). Resin composite was bonded to the surfaces using the GPDM-based SEA OptiBond XTR (Kerr), the 10-MDP-based SEA Clearfil SE Bond (Kuraray Noritake), or the 3-step etch-and-rinse adhesive (E&RA) OptiBond FL (Kerr) that served as the gold-standard control. After 1-week water storage at 37°C, specimens were serially cut into 1-mm2 stick-shaped microspecimens, of which half per tooth were further subjected to 20,000 thermocycles (TC) prior to µTBS testing. Data were statistically analyzed using ANOVA and the post-hoc Tukey test. The interfacial ultrastructure of the GPDM-based SEA OptiBond XTR with uncut and bur-cut enamel was additionally characterized with transmission electron microscopy (TEM). RESULTS: After 1-week water storage and upon TC aging, both SEAs bonded significantly (p < 0.05) less effectively to both bur-cut and uncut enamel than did the control OptiBond FL, except when OptiBond XTR was bonded to bur-cut enamel; then a similarly high µTBS was recorded (p > 0.05). TEM interfacial characterization revealed a tight interaction of Optibond XTR with both bur-cut and uncut enamel. CONCLUSION: The best bonding efficacy to enamel is still achieved by etching with phosphoric acid, following an E&R approach, while the higher etching efficacy of the GPDM-based SEA may result in equally effective bonding, provided that the enamel is bur-roughened first.

Luting of CAD/CAM ceramic inlays: direct composite versus dual-cure luting cement.

The aim of this study was to investigate bonding effectiveness in direct restorations. A two-step self-etch adhesive and a light-cure resin composite was compared with luting with a conventional dual-cure resin cement and a two-step etch and rinse adhesive. Class-I box-type cavities were prepared. Identical ceramic inlays were designed and fabricated with a computer-aided design/computer-aided manufacturing (CAD/CAM) device. The inlays were seated with Clearfil SE Bond/Clearfil AP-X (Kuraray Medical) or ExciTE F DSC/Variolink II (Ivoclar Vivadent), each by two operators (five teeth per group). The inlays were stored in water for one week at 37°C, whereafter micro-tensile bond strength testing was conducted. The micro-tensile bond strength of the direct composite was significantly higher than that from conventional luting, and was independent of the operator (P<0.0001). Pre-testing failures were only observed with the conventional method. High-power light-curing of a direct composite may be a viable alternative to luting lithium disilicate glass-ceramic CAD/CAM restorations.

Bond durability of self-adhesive composite cements to dentine.

OBJECTIVES: Clinically, the most easy-to-use composite cements are the so-called self-adhesive composite cements (SAC's). Hardly any data is however today available on the long-term bonding effectiveness of such luting composites. The purpose of this study was to evaluate the bond durability of different composite cements used to lute feldspathic ceramic blocks onto dentine. METHODS: Four SAC's (Clearfil SA Cement, Kuraray; G-CEM, GC; SmartCem2, Dentsply; Unicem 3M ESPE), one 'self-etch' (Clearfil Esthetic Cement, Kuraray) and one 'etch-and-rinse' (Variolink ll, Ivoclar-Vivadent) multi-step composite cement were used to lute feldspathic ceramic blocks (Vita Mark II, Vita) onto dentine surfaces. Teeth were distributed randomly in 24 experimental groups according to two different surface-preparation techniques ('SMEAR-COVERED' versus 'SMEAR-FREE') and storage conditions ('IMMEDIATE' versus 'AGED'). Failure patterns were evaluated with a stereomicroscope, and afterwards imaged using Feg-SEM. Two additional specimens were processed for cement-dentine interfacial analysis using TEM. RESULTS: A linear mixed effects statistical model revealed significant differences for the variables 'composite cement', 'surface preparation' and 'ageing'. All self-adhesive composite cements, except Unicem (3M ESPE), did bond less favourably to fractured dentine. TEM revealed an ultra-structurally different interaction of the composite cements with 'SMEAR-COVERED' and 'SMEAR-FREE' dentine. CONCLUSION: All SAC's suffered most when luted to 'SMEAR-FREE' (fractured) dentine, fortunately of no clinical relevance and most likely due to enhanced water sorption through the open tubules. When luted to 'SMEAR-COVERED' dentine, all SACs appeared equally effective and durable as the 'etch-and-rinse' and 'self-etch' multi-step composite cements. Solely the SAC SmartCem2 (Dentsply) appeared clearly less favourable and consistent.

Potential smear layer interference with bonding of self-etching adhesives to dentin.

PURPOSE: To evaluate the effect of smear-layer interposition on the bonding effectiveness of self-etching adhesives with different etching potential. MATERIALS AND METHODS: Bur-cut dentin specimens were obtained from 25 human molars after preparation of the dentin surface with a medium-grit diamond bur (bur-cut). An additional 25 molars were fractured at the midcoronal dentin to create a smear-layer-free surface (smear-free dentin). The prepared teeth were assigned to 5 groups, according to the adhesive to be applied: a strong one-step self-etching adhesive (PLP, Adper Prompt L-Pop, 3M ESPE, pH = 0.8); two ultra-mild one-step self-etching adhesives (C3S, Clearfil Tri-S Bond, Kuraray, pH = 2.7; AEB, Adper Easy Bond, 3M ESPE; pH = 2.7 ); as the self-etching control, a mild two-step self-etching adhesive (CSE, Clearfil SE Bond, Kuraray, pH of primer = 1.9); and as the etch-and-rinse control, a three-step etch-and-rinse adhesive (OFL, Optibond FL, Kerr). After composite buildups were made, all specimens were stored in distilled water (24 h/37°C) prior to microtensile bond strength testing (µTBS). The failure mode was determined with a stereomicroscope at 50X magnification. Representative µTBS specimens were processed for analysis in a Feg-SEM. The Kruskal-Wallis test was performed to determine statistical differences (p < 0.05). RESULTS: Except for the strong one-step self-etching adhesive, all other self-etching adhesives (mild and ultramild) revealed a significantly lower bond strength to bur-cut dentin than to smear-free dentin. The etch-and-rinse adhesive presented the highest µTBS, which was not significantly different when bonded to bur-cut or smear-free dentin. Fracture analysis demonstrated a prevalence of adhesive failures for the self-etching adhesives, while OFL revealed more mixed failures. SEM revealed that smear debris remained part of the adhesive interfacial complex produced by the ultra-mild one-step self-etching adhesive C3S when applied on bur-cut dentin. CONCLUSION: Smear debris interferes with the interaction of mild and ultra-mild self-etching adhesives with dentin.

Bonding effectiveness of self-adhesive composites to dentin and enamel.

UNLABELLED: Self-adhesive composites (SACs) are claimed to bond to tooth substrate without a separate adhesive. Bonding effectiveness data are however still limited. OBJECTIVES: In SubProject 1, the hypothesis was tested that the micro-tensile bond strength (µTBS) to dentin of two flowable SACs was alike that of a one-step self-etch adhesive (1-SEa) combined with a flowable composite (flowC). In SubProject 2, the hypothesis was tested that the nature of the smear layer did not affect the µTBS of the SACs to dentin/enamel. METHODS: SubProject 1: The µTBS to bur-cut dentin of two SACs (Fusio Liquid Dentin, Pentron; Vertise Flow, Kerr) was measured and compared to that of four 1-SEa/flowC combinations (AdheSe One/Tetric EvoFlow, Ivoclar Vivadent; Adper Prompt L-Pop/Filtek Supreme XT Flowable, 3M ESPE; iBond/Venus flow, Heraeus Kulzer; Xeno V/X-flow, Dentsply) and of one 3-step etch-and-rinse adhesive (3-E&Ra: OptiBond FL, Kerr) combined with Premise Flowable (Kerr). The effect of pre-etching dentin with phosphoric acid on the µTBS of the SAC Vertise Flow (Kerr) was measured as well. SubProject 2: The µTBS of the two SACs and one 1-SEa/flowC combination (Adper Prompt L-Pop/Filtek Supreme XT Flowable, 3M ESPE) to either bur-cut or SiC-paper ground dentin/enamel was measured. The effect of pre-etching enamel with phosphoric acid on the µTBS of the SAC Vertise Flow (Kerr) was also measured. RESULTS: SubProject 1: The µTBS to dentin of both SACs was significantly lower than that of the 1-SEa/flowC and the 3-E&Ra/flowC combinations, of which the latter performed best. The SAC Fusio Liquid Dentin (Pentron) bonded significantly better to dentin than Vertise Flow (Kerr), except when dentin had additionally been pre-etched with phosphoric acid. SubProject 2: Surface smear did not interfere with bonding of the SACs to dentin/enamel, while their µTBS remained significantly lower than that of the 1-SEa/flowC combination. Prior phosphoric-acid etching of dentin/enamel significantly ameliorated the bonding effectiveness of Vertise Flow (Kerr). SIGNIFICANCE: The bonding effectiveness of flowable SACs underscores that of 1-SEa's and one 'gold-standard' 3-E&Ra when combined with their proprietary flowable composite. Consequently, routine clinical application of SACs should be carefully considered.

New device for collecting intra-oral findings of unknown body.

In dental identification, the collection of intra-oral images is extremely important. We propose the Dental Watch(®) as a new device for collecting intra-oral findings in situations where sufficient jaw-opening or adequate lighting cannot be obtained in such cases of dead bodies within a day after death or burned bodies encountered in mass disaster. This device is an improved home video camera for taking intra-oral images. It is lightweight and cordless, allowing it to be operated with one hand, and an audio function allows comments to be made and recorded on obtaining findings at the same time as images are taken. In addition, this device allows images of the entire oral cavity to be taken comparatively easily, even when only a minimal degree of jaw movement is available. This device is extremely useful in situations where a single dentist inspector must obtain findings and make an accurate and detailed Dental Chart.

Dental erosion and sulfuric ion exposure levels in individuals working with sulfuric acid in lead storage battery manufacturing plant measured with mouth-rinse index.

To investigate dental erosion in employees working with sulfuric acid at a lead storage battery manufacturing plant and level of personal exposure to sulfuric ions, we measured sulfuric ion concentrations in the mouth rinse of those employees. We also measured exposure levels from air samples obtained from 2 employees from the same plant who did not work with sulfuric acid using a portable air sampler. At the same time, we collected and compared their mouth rinses with those from other employees. More specifically, we measured and compared sulfuric ion, calcium, and magnesium concentrations, along with pH levels from the mouth rinse of these two groups. Positive correlations were found between sulfuric ion and calcium concentrations (r=0.61, p<0.005), calcium and magnesium concentrations (r=0.61, p<0.005), Ca/Mg and calcium concentrations (r=0.64, p<0.005), and sulfuric ion and magnesium concentrations (r=0.55, p<0.005). Negative correlations were found between sulfuric ion concentrations and pH levels (r=-0.31, p<0.01), and magnesium concentrations and pH levels (r=-0.32, p<0.01). This suggests that mouth rinse from employees working with sulfuric acid could function as an indicator of sulfuric ion concentration in the work environment. Furthermore, this could lead to the development of a more accurate indicator of individual exposure.

Dental erosion in workers exposed to sulfuric acid in lead storage battery manufacturing facility.

Dental erosion, and specifically its symptoms, has long been studied in Japan as an occupational dental disease. However, in recent years, few studies have investigated the development of this disease or labor hygiene management aimed at its prevention. As a result, interest in dental erosion is comparatively low, even among dental professionals. Our investigation at a lead storage battery factory in 1991 found that the work environmental sulfuric acid density was above the tolerable range (1.0mg/m(3)) and that longterm workers had dental erosion. Therefore, workers handling sulfuric acid were given an oral examination and rates of dental erosion by tooth type, rates of erosion by number of working years and rates of erosion by sulfuric acid density in the work environment investigated. Where dental erosion was diagnosed, degree of erosion was identified according to a diagnostic criterion. No development of dental erosion was detected in the maxillary teeth, and erosion was concentrated in the anterior mandibular teeth. Its prevalence was as high as 20%. Rates of dental erosion rose precipitously after 10 working years. The percentages of workers with dental erosion were 42.9% for 10-14 years, 57.1% for 15-19 years and 66.7% for over 20 years with 22.5% for total number of workers. The percentages of workers with dental erosion rose in proportion to work environmental sulfuric acid density: 17.9% at 0.5-1.0, 25.0% at 1.0-4.0 and 50.0% at 4.0-8.0mg/m(3). This suggests that it is necessary to evaluate not only years of exposure to sulfuric acid but also sulfuric acid density in the air in factory workers.

Effects of light sources and visible light-activated titanium dioxide photocatalyst on bleaching.

The objective of this study was to evaluate, using methylene blue (MB), the effects of various light sources on the bleaching action of hydrogen peroxide (H(2)O(2)) with two titanium dioxide (TiO(2)) photocatalysts - an ultraviolet light-activated TiO(2) photocatalyst (UVTiO(2)) versus a visible light-activated TiO(2) photocatalyst (VL-TiO(2)). Five experimental solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), H(2)O(2), VL-TiO(2), UV-TiO(2)) were prepared by mixing varying concentrations of H(2)O(2 )and/or TiO(2 )photocatalyst with MB solution. For H(2)O(2)-containing solutions (VL-TiO(2)+H(2)O(2), UV-TiO(2)+H(2)O(2), and H(2)O(2)), the concentration of H(2)O(2) was adjusted to 3.5%. For the four different light sources, low- and high-intensity halogen lamps and blue LED LCUs were used. All the experimental solutions were irradiated by each of the light sources for 7 minutes, and the absorbance at 660 nm was measured every 30 seconds to determine the concentration of MB as an indicator of the bleaching effect. On the interaction between the effects of light source and bleaching treatment, the high-intensity halogen with VL-TiO(2)+H(2)O(2) caused the most significant reduction in MB concentration. On the effect of light sources, the halogen lamps resulted in a greater bleaching effect than the blue LED LCUs.