pa href=http://www.hubmed.org/fulltext.cgi?uids=22337700J Dent Res/a. 2012 Feb 15; brKitasako Y, Sadr A, Hamba H, Ikeda M, Tagami JpThe aim of this study was to assess the effect of chewing gum containing phosphoryl oligosaccharides of calcium (POs-Ca) and a low concentration of fluoride (F) on the hardness of enamel subsurface lesions, utilizing a double-blind, randomized, and controlled in situ model. Fifteen individuals wore removable lingual appliances with 3 bovine-enamel insets containing subsurface demineralized lesions. Three times a day for 14 days, they chewed one of the 3 chewing gums (placebo, POs-Ca, POs-Ca+F). After the treatment period, cross-sectional mineral content, nanoindentation hardness, and fluoride ion mapping by time-of-flight secondary ion mass spectrometry (TOF-SIMS) were evaluated. Although there were no statistical differences in overall mineral content and hardness recovery rates between POs-Ca and POs-Ca+F subsurface lesions (p 0.05), nanoindentation at 1-μm distance increments from the surface showed statistical differences in hardness recovery rate between POs-Ca and POs-Ca+F in the superficial 20-μm region (p 0.05). Fluoride mapping revealed distribution of the ion up to 20 μm from the surface in the POs-Ca+F group. Nanoindentation and TOF-SIMS results highlighted the benefits of bioavailability of fluoride ion on reinforcement of the superficial zone of subsurface lesions in situ (NCT01377493).
Ultramorphological Evaluation of the Dentin Acid-Base Resistant Zone of Two-step Self-etching Systems After Long-term Storage in Water.
pa href=http://www.hubmed.org/fulltext.cgi?uids=22282751J Adhes Dent/a. 2012 Jan 11; brIchikawa C, Nikaido T, Inoue G, Sadr A, Tagami JpPurpose: To evaluate the morphological changes in the acid-base resistant zone (ABRZ) at the resin/dentin interface after long-term storage in water. Materials and Methods: Two-step self-etching adhesive systems, Clearfil SE Bond (SE) and Clearfil Protect Bond (PB) (Kuraray Medical) were used. Human dentin disk sandwiches with resin composite were prepared, sectioned, and embedded in epoxy resin. The specimens were stored in water for 1 day, 1, 3 or 6 months, and then subjected to demineralizing solution and 5% NaOCl. The specimens were finally sectioned again, polished, argon-ion etched, and observed with SEM. Results: The outer lesion (OL) thickness at 1 day ranged from 10 to 15 μm but increased to approximately 30 μm after 6 months, suggesting gradual loss of dentin stored in water. A lower electron density was noted in the adhesives at the locations that were exposed to water. The ABRZs were observed clearly in all groups; the thickness of the ABRZ at the mid-point of the OL gradually decreased with time for SE. For PB, the thickness was stable up to 1 month, but decreased after 3 months. The bottom of the ABRZ in SE formed a right angle with dentin; in contrast, in PB, it sloped down toward dentin with a broadening bottom. Conclusions: Water storage resulted in changes both in the dentin substrate and the adhesive layer. An ABRZ was observed beneath the hybrid layer after long-term storage in water in both SE and PB. The ABRZ was thicker and relatively more stable in PB, probably due to fluoride release.
Intraoral pH measurement of carious lesions with qPCR of cariogenic bacteria to differentiate caries activity.
pa href=http://www.hubmed.org/fulltext.cgi?uids=22222970J Dent/a. 2011 Dec 23; brKuribayashi M, Kitasako Y, Matin K, Sadr A, Shida K, Tagami JpOBJECTIVES: A low pH environment is created by cariogenic bacteria. This study was aimed to measure pH of carious lesions intraorally using a micro-pH sensor, and assess predominant acid-producing cariogens by qPCR to differentiate caries activities. METHODS: 103 dentine lesions classified as active or arrested caries based on the clinical and radiological examinations were collected from patients after intraoral measurement of the lesion surface pH using a micro-pH sensor. Quantitative detection of genomic DNA copies of target cariogenic bacteria (mutans streptococci and Lactobacillus spp.) in each lesion was performed using real-time PCR. Correlation between the pH ranges and the number of bacterial species was examined by Spearman test. RESULTS: 50 samples were diagnosed as active and 53 as arrested lesions. Statistically significant difference was observed on average surface pH value between active and arrested lesions (p0.05). Prevalence of Lactobacillus spp. was higher in active lesions than in arrested lesions (76% vs. 58% of samples, respectively). When the carious lesions were categorised into four different pH ranges (up to 5.5, from 5.6 to 5.8, from 5.9 to 6.1 and 6.2 or above), increased prevalence of Lactobacillus spp. was observed with decrease of pH levels. A significant negative relationship was found between pH value and number of Lactobacillus spp. (r=-0.209, p0.05) but no such correlation was found for mutans streptococci. CONCLUSIONS: Intraoral pH measurement might be clinically useful to determine acidity of the local environment of carious lesions as one aspect of the caries activity assessment. CLINICAL SIGNIFICANCE: The population of certain bacteria may indicate activity of carious lesions. Intraoral pH measurement of the carious lesions using a micro-pH sensor may be a clinically feasible method for assessment of lesion acidity.
Nano-indentation testing of new and fractured nickel-titanium endodontic instruments.
pa href=http://www.hubmed.org/fulltext.cgi?uids=22211861Int Endod J/a. 2011 Dec 23; brJamleh A, Sadr A, Nomura N, Yahata Y, Ebihara A, Hanawa T, Tagami J, Suda HpJamleh A, Sadr A, Nomura N, Yahata Y, Ebihara A, Hanawa T, Tagami J, Suda H. Nano-indentation testing of new and fractured nickel-titanium endodontic instruments. International Endodontic Journal. ABSTRACT: Aim To investigate the effect of cyclic fatigue on nickel-titanium (NiTi) endodontic instruments using a nano-indentation test. Methodology Eight ProFile NiTi rotary instruments (size 30, taper 0.06; Dentsply Maillefer, Ballaigues, Switzerland) were tested using a cyclic fatigue set-up until fracture. The fractured instruments and eight new NiTi instruments of the same size and taper were used for a nano-indentation test on the internal surfaces of a NiTi instruments in the region just adjacent to their fractured edge (group I) and in the same region of the new group (group II), and the cutting part beside the shaft for both instruments [group III (fractured) and group IV (new)]. Data were statistically analyzed using one-way analysis of variance and Games-Howell post hoc test. The alpha-type error was set at 0.05. Results Significant differences in terms of hardness and elastic modulus for each group (P 0.05) were found, with group I having the lowest mean values followed by group III. Additionally, standard deviations increased remarkably after failure, as represented by groups I and III. Conclusion The nano-indentation technique can be applied to determine the performance and the failure mechanism of NiTi instruments. The fatigue process revealed a significant decrease in the hardness and elastic modulus of the NiTi instrument. As indicated by the low hardness, the fatigue process did not result in work hardening but rather work softening.
Nano-indentation testing of new and fractured nickel-titanium endodontic instruments.
pa href=http://www.hubmed.org/fulltext.cgi?uids=22211861Int Endod J/a. 2011 Dec 23; brJamleh A, Sadr A, Nomura N, Yahata Y, Ebihara A, Hanawa T, Tagami J, Suda HpJamleh A, Sadr A, Nomura N, Yahata Y, Ebihara A, Hanawa T, Tagami J, Suda H. Nano-indentation testing of new and fractured nickel-titanium endodontic instruments. International Endodontic Journal. ABSTRACT: Aim To investigate the effect of cyclic fatigue on nickel-titanium (NiTi) endodontic instruments using a nano-indentation test. Methodology Eight ProFile NiTi rotary instruments (size 30, taper 0.06; Dentsply Maillefer, Ballaigues, Switzerland) were tested using a cyclic fatigue set-up until fracture. The fractured instruments and eight new NiTi instruments of the same size and taper were used for a nano-indentation test on the internal surfaces of a NiTi instruments in the region just adjacent to their fractured edge (group I) and in the same region of the new group (group II), and the cutting part beside the shaft for both instruments [group III (fractured) and group IV (new)]. Data were statistically analyzed using one-way analysis of variance and Games-Howell post hoc test. The alpha-type error was set at 0.05. Results Significant differences in terms of hardness and elastic modulus for each group (P 0.05) were found, with group I having the lowest mean values followed by group III. Additionally, standard deviations increased remarkably after failure, as represented by groups I and III. Conclusion The nano-indentation technique can be applied to determine the performance and the failure mechanism of NiTi instruments. The fatigue process revealed a significant decrease in the hardness and elastic modulus of the NiTi instrument. As indicated by the low hardness, the fatigue process did not result in work hardening but rather work softening.
The Effects of Aging on Shear Bond Strength and Nanoleakage Expression of an Etch-and-Rinse Adhesive on Human Enamel and Dentin.
pa href=http://www.hubmed.org/fulltext.cgi?uids=22043472J Adhes Dent/a. 2011 Sep 26; brHariri I, Shimada Y, Sadr A, Ichinose S, Tagami JpPurpose: To evaluate the effects of increasing thermocycling regimens on bond strength and nanoleakage of an etch-and-rinse adhesive. Materials and Methods: Adper Single Bond (3M ESPE) was used for bonding resin composite to human enamel and dentin. Specimens were stored in water (37°C, 24 h) and subjected to thermocycling (5°C and 55°C) in five groups: 1. control (no thermal cycling), 2. 100, 3. 500, 4. 2000, or 5. 10,000 cycles. The microshear bond test was performed at a crosshead speed of 1 mm/min (n = 16). Nanoleakage specimens were immersed in silver nitrate and FE-SEM micrographs were digitally analyzed to calculate silver penetration in three samples. Results: The mean bond strength to enamel was not significantly affected by thermocycling. However, artificial aging decreased dentin bond strength in groups 4 and 5 compared to control. Weibull analysis indicated that the characteristic strength decreased gradually with aging in both substrates. All groups exhibited some nanoleakage, and a significant increase in silver penetration compared to the control was observed in enamel and dentin groups 2 to 5. Conclusion: A nanoleakage increase was detected in an earlier stage of aging than when a significant drop in bond strength was observed, with the dentin bond being more susceptible to deterioration.
The Effects of Aging on Shear Bond Strength and Nanoleakage Expression of an Etch-and-Rinse Adhesive on Human Enamel and Dentin.
pa href=http://www.hubmed.org/fulltext.cgi?uids=22043472J Adhes Dent/a. 2011 Sep 26; brHariri I, Shimada Y, Sadr A, Ichinose S, Tagami JpPurpose: To evaluate the effects of increasing thermocycling regimens on bond strength and nanoleakage of an etch-and-rinse adhesive. Materials and Methods: Adper Single Bond (3M ESPE) was used for bonding resin composite to human enamel and dentin. Specimens were stored in water (37°C, 24 h) and subjected to thermocycling (5°C and 55°C) in five groups: 1. control (no thermal cycling), 2. 100, 3. 500, 4. 2000, or 5. 10,000 cycles. The microshear bond test was performed at a crosshead speed of 1 mm/min (n = 16). Nanoleakage specimens were immersed in silver nitrate and FE-SEM micrographs were digitally analyzed to calculate silver penetration in three samples. Results: The mean bond strength to enamel was not significantly affected by thermocycling. However, artificial aging decreased dentin bond strength in groups 4 and 5 compared to control. Weibull analysis indicated that the characteristic strength decreased gradually with aging in both substrates. All groups exhibited some nanoleakage, and a significant increase in silver penetration compared to the control was observed in enamel and dentin groups 2 to 5. Conclusion: A nanoleakage increase was detected in an earlier stage of aging than when a significant drop in bond strength was observed, with the dentin bond being more susceptible to deterioration.
Effect of light units on tooth bleaching with visible-light activating titanium dioxide photocatalyst.
pa href=http://www.hubmed.org/fulltext.cgi?uids=21946494Dent Mater J/a. 2011 Sep 23; brKishi A, Otsuki M, Sadr A, Ikeda M, Tagami JpThis study evaluated the influence of different light sources on the efficiency of an office bleaching agent containing visible-light activating titanium dioxide photocatalyst (VL-TiO(2)) using an artificial discoloration tooth model. Extracted bovine teeth were stained by black tea. The CIE L*a*b* values were measured before and after nine consecutive treatments by the VL-TiO(2)-containing bleaching agent (TiON in Office, GC, Tokyo, Japan). A halogen light unit (CB; CoBee, GC) or an LED unit (G-light, GC) with two modes (blue and violet: GL-BV, blue: GL-B) were used to activate the bleaching agent in three groups (n=8). Brightness (ΔL) and color difference (ΔE) increased as bleaching repeated in all groups. Two-way ANOVA showed that both number of treatments and light sources significantly affected ΔE (p0.05). GL-BV showed better bleaching effect than GL-B. In measurement of irradiation spectra, CB showed a wide spectrum (380-530 nm), GL-B had a sharp peak at 470 nm and GL-BV showed an additional peak at 405 nm. It was concluded that the light source influenced the efficiency of the tooth bleaching with VL-TiO(2).
Long-term regional bond strength of three MMA-based adhesive resins in simulated vertical root fracture.
pa href=http://www.hubmed.org/fulltext.cgi?uids=21946486Dent Mater J/a. 2011 Sep 23; brNurrohman H, Nikaido T, Sadr A, Takagaki T, Kitayama S, Ikeda M, Waidyasekera K, Tagami JpThe purpose of this study was to investigate bond durability of MMA-based adhesives to root dentin in a simulated complete vertical root fracture (CVRF). The fractured fragments of human premolar root were reattached using Super-Bond CB (SB; Sun Medical), M-Bond or M-Bond II (MB or MB II; Tokuyama Dental). After storage for 1 day, 1 month, 6 months and 1 year, the reattached specimens were subjected to microtensile bond strength (µTBS) test at cervical and apical regions. Results showed that µTBS was significantly higher to cervical dentin than to apical dentin in MB and MB II, but not SB (p0.05). Significant decrease in µTBS was found for MB and MB II after 1 year, whereas no significant difference was found for SB (p0.05). Analysis of failure mode by SEM indicated differences over time. In conclusion, significant differences were found in the regional bond durability among MMA-based adhesives used to restore CVRF, that may lead to different clinical performances.
Effect of functional monomers in all-in-one adhesive systems on formation of enamel/dentin acid-base resistant zone.
pa href=http://www.hubmed.org/fulltext.cgi?uids=21946477Dent Mater J/a. 2011 Sep 23; brNikaido T, Ichikawa C, Li N, Takagaki T, Sadr A, Yoshida Y, Suzuki K, Tagami JpThis study aimed at evaluating the effect of functional monomers in all-in-one adhesive systems on formation of acid-base resistant zone (ABRZ) in enamel and dentin. Experimental adhesive systems containing one of three functional monomers; MDP, 3D-SR and 4-META were applied to enamel or dentin surface and light-cured. A universal resin composite was then placed. The specimens were subjected to a demineralizing solution (pH 4.5) and 5% NaClO for acid-base challenge and then observed by SEM. The ABRZ was clearly observed in both enamel and dentin interfaces. However, enamel ABRZ was thinner than dentin ABRZ in all adhesives. Morphology of the ABRZ was different between enamel and dentin, and also among the adhesives. Funnel-shaped erosion was observed only in the enamel specimen with the 4-META adhesive. The formation of enamel/dentin ABRZ was confirmed in all adhesives, but the morphology was influenced by the functional monomers.
Latest Papers
- Effects of structural orientation of enamel and dentine on light attenuation and local refractive index: An optical coherence tomography study.
- Gum Containing Calcium Fluoride Reinforces Enamel Subsurface Lesions in situ.
- Ultramorphological Evaluation of the Dentin Acid-Base Resistant Zone of Two-step Self-etching Systems After Long-term Storage in Water.
- Intraoral pH measurement of carious lesions with qPCR of cariogenic bacteria to differentiate caries activity.
- Nano-indentation testing of new and fractured nickel-titanium endodontic instruments.
- The Effects of Aging on Shear Bond Strength and Nanoleakage Expression of an Etch-and-Rinse Adhesive on Human Enamel and Dentin.
- Effect of light units on tooth bleaching with visible-light activating titanium dioxide photocatalyst.
- Long-term regional bond strength of three MMA-based adhesive resins in simulated vertical root fracture.
- Effect of functional monomers in all-in-one adhesive systems on formation of enamel/dentin acid-base resistant zone.
- Effects of a chewing gum containing phosphoryl oligosaccharides of calcium (POs-Ca) and fluoride on remineralization and crystallization of enamel subsurface lesions in situ.
- Evaluation of resin composite polymerization by three dimensional micro-CT imaging and nanoindentation.
- Estimation of lesion progress in artificial root caries by swept source optical coherence tomography in comparison to transverse microradiography.
- Non-invasive quantification of resin-dentin interfacial gaps using optical coherence tomography: validation against confocal microscopy.
- Roughness and pH changes of enamel surface induced by soft drinks in vitro-applications of stylus profilometry, focus variation 3D scanning microscopy and micro pH sensor.
- Effect of curing modes of dual-curing core systems on microtensile bond strength to dentin and formation of an acid-base resistant zone.
- Effects of CPP-ACP with sodium fluoride on inhibition of bovine enamel demineralization: a quantitative assessment using micro-computed tomography.
- Non-destructive 3D imaging of composite restorations using optical coherence tomography: marginal adaptation of self-etch adhesives.
- Adhesion of Epiphany self-etch sealer to dentin treated with intracanal irrigating solutions.
- Ultrastructural observation of the acid-base resistant zone of all-in-one adhesives using three different acid-base challenges.
- CO2 laser improves 45S5 bioglass interaction with dentin.
