Artificial Intelligence and Acute Stroke Imaging.

Artificial intelligence technology is a rapidly expanding field with many applications in acute stroke imaging, including ischemic and hemorrhage subtypes. Early identification of acute stroke is critical for initiating prompt intervention to reduce morbidity and mortality. Artificial intelligence can help with various aspects of the stroke treatment paradigm, including infarct or hemorrhage detection, segmentation, classification, large vessel occlusion detection, Alberta Stroke Program Early CT Score grading, and prognostication. In particular, emerging artificial intelligence techniques such as convolutional neural networks show promise in performing these imaging-based tasks efficiently and accurately. The purpose of this review is twofold: first, to describe AI methods and available public and commercial platforms in stroke imaging, and second, to summarize the literature of current artificial intelligence-driven applications for acute stroke triage, surveillance, and prediction.

Effects of pruritogens and algogens on rostral ventromedial medullary ON and OFF cells.

Rostroventromedial medulla (RVM) ON and OFF cells are thought to facilitate and inhibit spinal nociceptive transmission, respectively. However, it is unknown how ON and OFF cells respond to pruritic stimuli or how they contribute to descending modulation of spinal itch signaling. In pentobarbital sodium-anesthetized mice, single-unit recordings were made in RVM from ON and OFF cells identified by their respective increase or decrease in firing that occurred just before nocifensive hindlimb withdrawal elicited by paw pinch. Of RVM ON cells, 75% (21/28) were excited by intradermal histamine, 50% (10/20) by intradermal chloroquine, and 75% (27/36) by intradermal capsaicin. Most chemically responsive units also responded to a scratch stimulus applied to the injected hindpaw. Few ON cells responded to intradermal injection of vehicle (saline: 5/32; Tween 2/17) but still responded to scratching. For OFF cells, intradermal histamine and scratching inhibited 32% (6/19) with no effect of histamine in the remainder. Intradermal chloroquine inhibited 44% (4/9) and intradermal capsaicin inhibited 61% (11/18) of OFF cells. Few OFF cells were affected by vehicles (Tween: 1 inhibited, 7 unaffected; saline: 3 excited, 1 inhibited, 8 unaffected). Both ON and OFF cells that responded to one chemical usually also responded to others, whereas units unresponsive to the first-tested chemical tended not to respond to others. These results indicate that ascending pruriceptive signals activate RVM ON cells and inhibit RVM OFF cells. These effects are considered to facilitate and disinhibit spinal pain transmission, respectively. It is currently not clear if spinal itch transmission is similarly modulated. NEW & NOTEWORTHY The rostroventromedial medulla (RVM) contains ON and OFF cells that are, respectively, excited and inhibited by noxious stimuli and have descending projections that facilitate and inhibit spinal nociceptive transmission. Most RVM ON cells were excited, and OFF cells inhibited, by intradermal injection of the pruritogens histamine and chloroquine, as well as the algogen capsaicin. These results indicate that itchy stimuli activate RVM neurons that presumably give rise to descending modulation of spinal itch transmission.

Innocuous warming enhances peripheral serotonergic itch signaling and evokes enhanced responses in serotonin-responsive dorsal horn neurons in the mouse.

Itch is often triggered by warming the skin in patients with itchy dermatitis, but the underlying mechanism is largely unknown. We presently investigated if warming the skin enhances histamine- or serotonin (5-HT)-evoked itch behavior or responses of sensory dorsal root ganglion (DRG) cells, and if responses of superficial dorsal horn neurons to innocuous warming are enhanced by these pruritogens. In a temperature-controlled environmental chamber, mice exhibited greater scratching following intradermal injection of 5-HT, but not histamine, SLIGRL, or BAM8-22, when the skin surface temperature was above 36°C. Calcium imaging of DRG cells in a temperature-controlled bath revealed that responses to 5-HT, but not histamine, were significantly greater at a bath temperature of 35°C vs. lower temperatures. Single-unit recordings revealed a subpopulation of superficial dorsal horn neurons responsive to intradermal injection of 5-HT. Of these, 58% responded to innocuous skin warming (37°C) prior to intradermal injection of 5-HT, while 100% responded to warming following intradermal injection of 5-HT. Warming-evoked responses were superimposed on the 5-HT-evoked elevation in firing and were significantly larger compared with responses pre-5-HT, as long as 30 min after the intradermal injection of 5-HT. Five-HT-insensitive units, and units that either did or did not respond to intradermal histamine, did not exhibit any increase in the incidence of warmth sensitivity or in the mean response to warming following intradermal injection of the pruritogen. The results suggest that 5-HT-evoked responses of pruriceptors are enhanced during skin warming, leading to increased firing of 5-HT-sensitive dorsal horn neurons that signal nonhistaminergic itch. NEW & NOTEWORTHY: Skin warming often exacerbates itch in patients with itchy dermatitis. We demonstrate that warming the skin enhanced serotonin-evoked, but not histamine-evoked, itch behavior and responses of sensory dorsal root ganglion cells. Moreover, serotonin, but not histamine, enhanced responses of superficial dorsal horn neurons to innocuous warming. The results suggest that skin warming selectively enhances the responses of serotonin-sensitive pruriceptors, leading to increased firing of serotonin-sensitive dorsal horn neurons that signal nonhistaminergic itch.

High transmission Ni compound refractive lens for high energy X-rays.

We present a new planar Ni compound refractive lens for high energy X-rays (116 keV). The lens is composed of identical plano-concave elements with longitudinal parabolic grooves manufactured by a punch technique. In order to increase the lens transmission, the thickness of the single lens at the parabolic groove vertex was reduced to less than 5 µm and the radius of curvature was reduced to about 20 µm. The small radius of curvature allowed us to reduce the number of single elements needed to get the focal length of 3 m to 54 single lenses. The gain parameter has been significantly improved compared to the previous lenses due to higher transmission, but the focused beam size and its gain are not as good as expected, mostly due to the aberrations caused by the lens shape imperfections.

The longitudinal mental health impact of Fukushima nuclear disaster exposures and public criticism among power plant workers: the Fukushima NEWS Project study.

BACKGROUND: The Fukushima Daiichi and Daini Nuclear Power Plant workers experienced multiple stressors as both victims and onsite workers after the 2011 Great East Japan Earthquake and subsequent nuclear accidents. Previous studies found that disaster-related exposures, including discrimination/slurs, were associated with their mental health. Their long-term impact has yet to be investigated. METHOD: A total of 968 plant workers (Daiichi, n = 571; Daini, n = 397) completed self-written questionnaires 2-3 months (time 1) and 14-15 months (time 2) after the disaster (response rate 55.0%). Sociodemographics, disaster-related experiences, and peritraumatic distress were assessed at time 1. At time 1 and time 2, general psychological distress (GPD) and post-traumatic stress response (PTSR) were measured, respectively, using the K6 scale and Impact of Event Scale Revised. We examined multivariate covariates of time 2 GPD and PTSR, adjusting for autocorrelations in the hierarchical multiple regression analyses. RESULTS: Higher GPD at time 2 was predicted by higher GPD at time 1 (ß = 0.491, p < 0.001) and discrimination/slurs experiences at time 1 (ß = 0.065, p = 0.025, adjusted R 2 = 0.24). Higher PTSR at time 2 was predicted with higher PTSR at time 1 (ß = 0.548, p < 0.001), higher age (ß = 0.085, p = 0.005), and discrimination/slurs experiences at time 1 (ß = 0.079, p = 0.003, adjusted R 2 = 0.36). CONCLUSIONS: Higher GPD at time 2 was predicted by higher GPD and discrimination/slurs experience at time 1. Higher PTSR at time 2 was predicted by higher PTSR, higher age, and discrimination/slurs experience at time 1.

Intradermal endothelin-1 excites bombesin-responsive superficial dorsal horn neurons in the mouse.

Endothelin-1 (ET-1) has been implicated in nonhistaminergic itch. Here we used electrophysiological methods to investigate whether mouse superficial dorsal horn neurons respond to intradermal (id) injection of ET-1 and whether ET-1-sensitive neurons additionally respond to other pruritic and algesic stimuli or spinal superfusion of bombesin, a homolog of gastrin-releasing peptide (GRP) that excites spinal itch-signaling neurons. Single-unit recordings were made from lumbar dorsal horn neurons in pentobarbital-anesthetized C57BL/6 mice. We searched for units that exhibited elevated firing after id injection of ET-1 (1 µg/µl). Responsive units were further tested with mechanical stimuli, bombesin (spinal superfusion, 200 µg·ml(-1)·min(-1)), heating, cooling, and additional chemicals [histamine, chloroquine, allyl isothiocyanate (AITC), capsaicin]. Of 40 ET-1-responsive units, 48% responded to brush and pinch [wide dynamic range (WDR)] and 52% to pinch only [high threshold (HT)]. Ninety-three percent responded to noxious heat, 50% to cooling, and >70% to histamine, chloroquine, AITC, and capsaicin. Fifty-seven percent responded to bombesin, suggesting that they participate in spinal itch transmission. That most ET-1-sensitive spinal neurons also responded to pruritic and algesic stimuli is consistent with previous studies of pruritogen-responsive dorsal horn neurons. We previously hypothesized that pruritogen-sensitive neurons signal itch. The observation that ET-1 activates nociceptive neurons suggests that both itch and pain signals may be generated by ET-1 to result in simultaneous sensations of itch and pain, consistent with observations that ET-1 elicits both itch- and pain-related behaviors in animals and burning itch sensations in humans.

Behavioral model of itch, alloknesis, pain and allodynia in the lower hindlimb and correlative responses of lumbar dorsal horn neurons in the mouse.

We have further developed a behavioral model of itch and pain in the lower hindlimb (calf) originally reported by LaMotte et al. (2011) that allows comparisons with responses of lumbar dorsal horn neurons to pruritic and noxious stimuli. Intradermal (id) microinjection of the pruritogens histamine, SLIGRL-NH2 (agonist of PAR-2 and MrgprC11) and chloroquine (agonist of MrgprA3) into the calf of the lower limb elicited significant biting and a small amount of licking directed to the injection site, over a 30-min time course. Following id injection of histamine, low-threshold mechanical stimuli reliably elicited discrete episodes of biting (alloknesis) over a longer time course; significantly less alloknesis was observed following id injection of SLIGRL-NH2. Capsaicin injections elicited licking but little biting. Following id injection of capsaicin, low-threshold mechanical stimuli elicited discrete hindlimb flinches (allodynia) over a prolonged (>2h) time course. In single-unit recordings from superficial lumbar dorsal horn neurons, low-threshold mechanically evoked responses were significantly enhanced, accompanied by receptive field expansion, following id injection of histamine in histamine-responsive neurons. This was not observed in histamine-insensitive neurons, or following id injection of saline or SLIGRL-NH2, regardless of whether the latter activated the neuron or not. These results suggest that itch-responsive neurons are selectively sensitized by histamine but not SLIGRL-NH2 to account for alloknesis. The presently described "calf" model appears to distinguish between itch- and pain-related behavioral responses, and provides a basis to investigate lumbar spinal neural mechanisms underlying itch, alloknesis, pain and allodynia.

Cross-sensitization of histamine-independent itch in mouse primary sensory neurons.

Overexpression of pruritogens and their precursors may contribute to the sensitization of histamine-dependent and -independent itch-signaling pathways in chronic itch. We presently investigated self- and cross-sensitization of scratching behavior elicited by various pruritogens, and their effects on primary sensory neurons. The MrgprC11 agonist BAM8-22 exhibited self- and reciprocal cross-sensitization of scratching evoked by the protease-activated receptor-2 (PAR-2) agonist SLIGRL. The MrgprA3 agonist chloroquine unidirectionally cross-sensitized BAM8-22-evoked scratching. Histamine unidirectionally cross-sensitized scratching evoked by chloroquine and BAM8-22. SLIGRL unidirectionally cross-sensitized scratching evoked by chloroquine. Dorsal root ganglion (DRG) cells responded to various combinations of pruritogens and algogens. Neither chloroquine, BAM8-22 nor histamine had any effect on responses of DRG cell responses to subsequently applied pruritogens, implying that their behavioral self- and cross-sensitization effects are mediated indirectly. SLIGRL unilaterally cross-sensitized responses of DRG cells to chloroquine and BAM8-22, consistent with the behavioral data. These results indicate that unidirectional cross-sensitization of histamine-independent itch-signaling pathways might occur at a peripheral site through PAR-2. PAR-2 expressed in pruriceptive nerve endings is a potential target to reduce sensitization associated with chronic itch.

Efficacy of the dietary histone deacetylase inhibitor butyrate alone or in combination with vitamin A against proliferation of MCF-7 human breast cancer cells

The combined treatment with histone deacetylase inhibitors (HDACi) and retinoids has been suggested as a potential epigenetic strategy for the control of cancer. In the present study, we investigated the effects of treatment with butyrate, a dietary HDACi, combined with vitamin A on MCF-7 human breast cancer cells. Cell proliferation was evaluated by the crystal violet staining method. MCF-7 cells were plated at 5 x 10(4) cells/mL and treated with butyrate (1 mM) alone or combined with vitamin A (10 µM) for 24 to 120 h. Cell proliferation inhibition was 34, 10 and 46% following treatment with butyrate, vitamin A and their combination, respectively, suggesting that vitamin A potentiated the inhibitory activities of butyrate. Furthermore, exposure to this short-chain fatty acid increased the level of histone H3K9 acetylation by 9.5-fold (Western blot), but not of H4K16, and increased the expression levels of p21WAF1 by 2.7-fold (Western blot) and of RARβ by 2.0-fold (quantitative real-time PCR). Our data show that RARβ may represent a molecular target for butyrate in breast cancer cells. Due to its effectiveness as a dietary HDACi, butyrate should be considered for use in combinatorial strategies with more active retinoids, especially in breast cancers in which RARβ is epigenetically altered.

E-cadherin in canine mast cell tumors: decreased expression and altered subcellular localization in Grade 3 tumors.

Mast cell tumors (MCTs) are the most frequent round cell tumors in dogs and comprise approximately 21% of all canine cutaneous tumors. MCTs are highly invasive and metastatic corresponding to the histological grade. E-cadherin is an adhesion molecule expressed in epithelial cells and although it is an epithelial cellular marker, studies have shown expression of E-cadherin in canine round cell tumors. To better characterize the expression pattern of E-cadherin in several different histological grades of MCTs in dogs, the expression and localization of the adhesion molecule was investigated using immunohistochemistry. For this purpose, 18 cutaneous MCTs were classified into three histological grades, 1, 2 or 3. Clinical history and follow-up data were available for all of the dogs. Cytoplasmic and nuclear expressions of E-cadherin in all three types of tumors were verified by immunostaining using two different antibodies. There was decreased E-cadherin expression in the more aggressive MCTs (Grade 3), suggesting an association between E-cadherin and tumor aggressiveness. Additionally, the loss of E-cadherin expression in either the cytoplasm or nucleus in more aggressive and undifferentiated tumor types confirmed the importance of cellular adhesion in tumor behavior.

Efficacy of the dietary histone deacetylase inhibitor butyrate alone or in combination with vitamin A against proliferation of MCF-7 human breast cancer cells.

The combined treatment with histone deacetylase inhibitors (HDACi) and retinoids has been suggested as a potential epigenetic strategy for the control of cancer. In the present study, we investigated the effects of treatment with butyrate, a dietary HDACi, combined with vitamin A on MCF-7 human breast cancer cells. Cell proliferation was evaluated by the crystal violet staining method. MCF-7 cells were plated at 5 x 10(4) cells/mL and treated with butyrate (1 mM) alone or combined with vitamin A (10 µM) for 24 to 120 h. Cell proliferation inhibition was 34, 10 and 46% following treatment with butyrate, vitamin A and their combination, respectively, suggesting that vitamin A potentiated the inhibitory activities of butyrate. Furthermore, exposure to this short-chain fatty acid increased the level of histone H3K9 acetylation by 9.5-fold (Western blot), but not of H4K16, and increased the expression levels of p21WAF1 by 2.7-fold (Western blot) and of RARß by 2.0-fold (quantitative real-time PCR). Our data show that RARß may represent a molecular target for butyrate in breast cancer cells. Due to its effectiveness as a dietary HDACi, butyrate should be considered for use in combinatorial strategies with more active retinoids, especially in breast cancers in which RARß is epigenetically altered.

In vitro chemosensitivity of canine mast cell tumors grades II and III to all-trans-retinoic acid (ATRA).

Mast cell tumor (MCT) is one of the most prevalent neoplasms that affect the skin and soft tissue of dogs. Because mast cell tumors present a great variety of clinical appearance and behavior, their treatment becomes a challenge. While retinoids are well recognized as promising antitumor agents, there have been only a few reports about retinoids' effect on canine cancers. The aim of this study was to investigate the chemosensitivity of MCT grades II and III to all-trans retinoic acid (ATRA). Immediately after surgical resection, MCT were prepared for primary culture. Samples of MCTs were also fixed in formalin for histopathology and grading according to the classification of Patnaik et al. (Veterinary Pathology 21(5):469-474, 1984). The best results were obtained when neoplastic mast cells were co-cultivated with fibroblasts. Cultured mast cells were, then, treated with concentrations of 10(-4) to 10(-7) M of ATRA, in order to evaluate their chemosensitivity to this retinoid. MTT assay was performed to estimate cell growth and death. The highest level of mast cell chemosensivity was obtained at the dose of 10(-4) M (p < 0,002). MCT of grades II or III were equally susceptible to the treatment with ATRA. Cell death was observed on the first 24 h until 48 h. According to these results, ATRA may be a potential chemotherapeutic agent for the treatment of canine MCT.

Paullinia cupana Mart var. sorbilis, guaraná, reduces cell proliferation and increases apoptosis of B16/F10 melanoma lung metastases in mice.

We showed that guaraná (Paullinia cupana Mart var. sorbilis) had a chemopreventive effect on mouse hepatocarcinogenesis and reduced diethylnitrosamine-induced DNA damage. In the present experiment, we evaluated the effects of guaraná in an experimental metastasis model. Cultured B16/F10 melanoma cells (5 x 10(5) cells/animal) were injected into the tail vein of mice on the 7th day of guaraná treatment (2.0 mg P. cupana/g body weight, per gavage) and the animals were treated with guaraná daily up to 14 days until euthanasia (total treatment time: 21 days). Lung sections were obtained for morphometric analysis, apoptotic bodies were counted to calculate the apoptotic index and proliferating cell nuclear antigen-positive cells were counted to determine the proliferation index. Guaraná-treated (GUA) animals presented a 68.6% reduction in tumor burden area compared to control (CO) animals which were not treated with guaraná (CO: 0.84 +/- 0.26, N = 6; GUA: 0.27 +/- 0.24, N = 6; P = 0.0043), a 57.9% reduction in tumor proliferation index (CO: 23.75 +/- 20.54, N = 6; GUA: 9.99 +/- 3.93, N = 6; P = 0.026) and a 4.85-fold increase in apoptotic index (CO: 66.95 +/- 22.95, N = 6; GUA: 324.37 +/- 266.74 AB/mm(2), N = 6; P = 0.0152). In this mouse model, guaraná treatment decreased proliferation and increased apoptosis of tumor cells, consequently reducing the tumor burden area. We are currently investigating the molecular pathways of the effects of guaraná in cultured melanoma cells, regarding principally the cell cycle inhibitors and cyclins.

Molecular epidemiology of Mycobacterium tuberculosis in an urban area in Japan, 2002-2006.

SETTING: Shinjuku City, Tokyo, Japan. OBJECTIVE: To evaluate the status of transmission of Mycobacterium tuberculosis in Shinjuku City to allocate resources efficiently and effectively for a successful tuberculosis (TB) control programme. DESIGN: Observational descriptive study combining the genotype data of M. tuberculosis with TB patient profiles. RESULTS: The genotype clustering rate was significantly higher in males (adjusted odds ratio [aOR] 1.94, 95%CI 1.04-3.65, P = 0.038), patients aged <40 years (aOR 2.09, 95%CI 1.17-3.71, P = 0.012) and the homeless (aOR 2.72, 95%CI 1.42-5.20, P = 0.002), and was lower for the foreign-born (aOR 0.21, 95%CI 0.06-0.76, P = 0.017). Among 45 genotype clusters containing 152 TB patients, 26 clusters containing 102 patients (67.1%) were composed of a mix of homeless and non-homeless patients. One of the mixed clusters included an 8-month-old infant born in Japan. CONCLUSION: The study revealed that M. tuberculosis transmission occurred more frequently among the homeless than in non-homeless persons. However, transmission by casual contact between the homeless and the general population was also shown to occur.

Paullinia cupana Mart var. sorbilis, guaraná, reduces cell proliferation and increases apoptosis of B16/F10 melanoma lung metastases in mice

We showed that guaraná (Paullinia cupana Mart var. sorbilis) had a chemopreventive effect on mouse hepatocarcinogenesis and reduced diethylnitrosamine-induced DNA damage. In the present experiment, we evaluated the effects of guaraná in an experimental metastasis model. Cultured B16/F10 melanoma cells (5 x 10(5) cells/animal) were injected into the tail vein of mice on the 7th day of guaraná treatment (2.0 mg P. cupana/g body weight, per gavage) and the animals were treated with guaraná daily up to 14 days until euthanasia (total treatment time: 21 days). Lung sections were obtained for morphometric analysis, apoptotic bodies were counted to calculate the apoptotic index and proliferating cell nuclear antigen-positive cells were counted to determine the proliferation index. Guaraná-treated (GUA) animals presented a 68.6 percent reduction in tumor burden area compared to control (CO) animals which were not treated with guaraná (CO: 0.84 ± 0.26, N = 6; GUA: 0.27 ± 0.24, N = 6; P = 0.0043), a 57.9 percent reduction in tumor proliferation index (CO: 23.75 ± 20.54, N = 6; GUA: 9.99 ± 3.93, N = 6; P = 0.026) and a 4.85-fold increase in apoptotic index (CO: 66.95 ± 22.95, N = 6; GUA: 324.37 ± 266.74 AB/mm², N = 6; P = 0.0152). In this mouse model, guaraná treatment decreased proliferation and increased apoptosis of tumor cells, consequently reducing the tumor burden area. We are currently investigating the molecular pathways of the effects of guaraná in cultured melanoma cells, regarding principally the cell cycle inhibitors and cyclins.

Effect of fluoride-releasing adhesive system on decalcified dentin.

The aim of this study was to evaluate the effect of fluoride-releasing adhesive systems on human decalcified dentin in vitro. Two fluoride-releasing adhesive systems, Reactmer bond (RB, Shofu) and ABF (AF, Kuraray), an experimental system, and a commercial adhesive system without fluoride release, SE bond (SE, Kuraray), were used in this study. The amount of fluoride release from adhesive in deionized water was measured every week for 10 weeks. Class V cavities were prepared on extracted human pre-molars and decalcified dentin was promoted by using a bacterial caries induction system at the cavity floor. The cavities preserving decalcified dentin were restored with resin composite (AP-X, Kuraray) after treatment by each adhesive system. The specimens without treatment by adhesive system and restoration were used for control. The specimens with restoration were then incubated for 4 weeks at 37 degrees C, 100% humidity. Microradiographs of the specimens showed that the radiopacities of the decalcified dentin layers in RB and AF groups with fluoride release were significantly higher than those in SE or control groups without fluoride release. This result suggested that the fluoride-releasing adhesive systems enhanced mineralization of decalcified dentin.

Inhibition of artificial secondary caries by fluoride-releasing adhesives on root dentin.

Fluoride-releasing materials can be expected to inhibit the secondary caries. The aim;of this study was to evaluate the effect of fluoride-releasing adhesives on inhibition of secondary caries in outer and wall lesions. Two commercial fluoride-releasing adhesives, Reactmer bond (RB) and One-up bond F (OB), and a commercial adhesive without fluoride release, Mac-bond II (MB), were used prior to placement of restorative materials without fluoride release, Lite-fil II A (LF) and Estelite (EL), and a fluoride-releasing restorative material, Reactmer paste (RP). Class V cavities prepared on extracted human premolars were restored with various combinations of the materials: MB/EL, OB/EL, RB/LF and RB/RP. The restored teeth were incubated in bacterial medium containing sucrose with Streptoccus mutans for 14 days. Microradiographs of specimens showed no wall lesions in all groups and an acid-resistant layer adjacent to the restoration in the caries-like lesion. OB/EL, RB/LF and RB/RP groups showed thicker layers than the MB/EL group. The RB/RP group formed the shallowest outer lesion among all groups. These results indicate that fluoride-releasing adhesives are effective in the prevention of wall lesions but exhibit little outer lesion inhibition. Therefore, combined restoration using a fluoride-releasing adhesive and fluoride-releasing restorative material should be selected to inhibit secondary caries.

Effect of adhesives on the inhibition of secondary caries around compomer restorations.

This study evaluated the effect of adhesives on the inhibition of secondary caries around compomer restorations in vitro. Two adhesive systems with a Bis-GMA resin, Scotch bond Multi-purpose (MP) and Single Bond (SB), and one adhesive system with no Bis-GMA resin, F2000 compomer primer/adhesive (PA), were used prior to placement of the compomer (F2000), and non-fluoride releasing resin composite (Z100) was used as a control. Class V cavities prepared on extracted human premolars were restored with various combinations of materials: F2000/MP, F2000/SB, F2000/PA, Z100/MP, Z100/SB and Z100/PA. The restored teeth were incubated in bacterial medium containing sucrose with Streptococcus mutans for two weeks after storage for 14 days. On microradiographs, the radio-opaque layers adjacent to the F2000 restorations were thick and clear, while the layers in the Z100 restorations were unclear. In the F2000 restorations, the mean thickness of the radio-opaque layers in the PA group was significantly greater than that of the MP and SB groups. In fluoride-releasing measurement, F2000 coated with PA showed a significantly higher amount of fluoride release than MP and SB, and no significant difference in the amount of fluoride release from uncoated F2000. These results indicated that applying an adhesive without Bis-GMA resin to compomer restoration has no suppressive effect on the fluoride release from compomer and might be beneficial for inhibiting secondary caries in vitro.

Inhibition of artificial secondary caries in root by fluoride-releasing restorative materials.

This investigation evaluated the fluoride-releasing properties of various fluoride-releasing restorative materials, including resin-modified glass-ionomer cements (Fuji ionomer TypeII LC, Photac-Fil Aplicap, Vitremer), compomers (Ionosit FIL, Compoglass, Dyract) and fluoride-releasing resin composites (Heliomolar radiopaque, Degufill mineral). The study also estimated the effects of those materials on the inhibition of artificial secondary caries around restorations using a bacterial caries-inducing system. The amount of fluoride released from the materials in deionized water was measured every one week for 10 weeks. Class V cavities with the gingival margin located in the root were prepared in extracted human premolars and restored with each of the materials. The restored teeth were incubated in the bacterial artificial caries chamber, and the artificial lesion created around the restoration was observed microradiographically. The resin-modified glass-ionomer cements released the largest amount of fluoride and created a thick radio-opaque zone in the artificial lesion along the restoration-dentin interface. These results indicated that the fluoride-releasing restorative materials have the potential to inhibit secondary caries formation around restorations. Resin-modified glass-ionomer cements presented a particularly strong effect, compared with compomers and fluoride-releasing resin composites.