Chenopodium ambrosioides L. Reduces Synovial Inflammation and Pain in Experimental Osteoarthritis.

The chronicity of osteoarthritis (OA), characterized by pain and inflammation in the joints, is linked to a glutamate receptor, N-methyl-D-aspartate (NMDA). The use of plant species such as Chenopodium ambrosioides L. (Amaranthaceae) as NMDA antagonists offers a promising perspective. This work aims to analyze the antinociceptive and anti-inflammatory responses of the crude hydroalcoholic extract (HCE) of C. ambrosioides leaves in an experimental OA model. Wistar rats were separated into six groups (n = 24): clean (C), negative control (CTL-), positive control (CTL+), HCE0.5, HCE5 and HCE50. The first group received no intervention. The other groups received an intra-articular injection of sodium monoiodoacetate (MIA) (8 mg/kg) on day 0. After six hours, they were orally treated with saline, Maxicam plus (meloxicam + chondroitin sulfate) and HCE at doses of 0.5 mg/kg, 5 mg/kg and 50 mg/kg, respectively. After three, seven and ten days, clinical evaluations were performed (knee diameter, mechanical allodynia, mechanical hyperalgesia and motor activity). On the tenth day, after euthanasia, synovial fluid and draining lymph node were collected for cellular quantification, and cartilage was collected for histopathological analysis. Finally, molecular docking was performed to evaluate the compatibility of ascaridole, a monoterpene found in HCE, with the NMDA receptor. After the third day, HCE reduced knee edema. HCE5 showed less cellular infiltrate in the cartilage and synovium and lower intensities of allodynia from the third day and of hyperalgesia from the seventh day up to the last treatment day. The HCE5 and HCE50 groups improved in forced walking. In relation to molecular docking, ascaridole showed NMDA receptor binding affinity. C. ambrosioides HCE was effective in the treatment of OA because it reduced synovial inflammation and behavioral changes due to pain. This effect may be related to the antagonistic effect of ascaridole on the NMDA receptor.

Combinations of ascaridole, carvacrol, and caryophyllene oxide against Leishmania.

To date there are no vaccines against Leishmania and chemotherapy remains the mainstay for the control of leishmaniasis. The drugs currently used for leishmaniasis therapy are significantly toxic, expensive, and result in a growing frequency of refractory infections. In this study, we evaluated the effect of combinations of the main components of essential oil from Chenopodium ambrosioides (ascaridole, carvacrol, and caryophyllene oxide) against Leishmaniaamazonensis. Anti-leishmanial effects of combinations of pure compounds were evaluated in vitro and the fractional inhibitory concentration (FIC) indices were calculated. BALB/c mice infected with L. amazonensis were treated with different concentrations of ascaridole-carvacrol combinations by intralesional doses every 4 days. Disease progression and parasite burden in infected tissues were determined. In vitro experiments showed a synergistic effect of the combination of ascaridole-carvacrol against promastigotes of Leishmania with a FIC index of 0.171, while indifferent activities were observed for ascaridole-caryophyllene oxide (FIC index=3.613) and carvacrol-caryophyllene oxide (FIC index=2.356) combinations. The fixed ratio method showed that a 1:4 ascaridole-carvacrol ratio produced a better anti-protozoal activity on promastigotes, lower cytotoxicity, and synergistic activity on intracellular amastigotes (FIC index=0.416). Significant differences (p<0.05) in lesion size and parasite burden were demonstrated in BALB/c mice experimentally infected and treated with the ascaridole-carvacrol combinations compared with control animals. Carvacrol showed significant higher anti-radical activity in the DPPH assay compared with caryophyllene oxide. Electron spin resonance spectroscopy in combination with spin trapping suggested the presence of carbon-centered radicals after activation of ascaridole by Fe(2+). The intensity of the signals is preferably decreased upon addition of carvacrol. The ascaridole-carvacrol combination could represent a future alternative to monotherapeutic anti-leishmanial agents.

The optimal patch test concentration for ascaridole as a sensitizing component of tea tree oil.

BACKGROUND: Tea tree oil is used as a natural remedy, but is also a popular ingredient in household and cosmetic products. Oxidation of tea tree oil results in degradation products, such as ascaridole, which may cause allergic contact dermatitis. OBJECTIVES: To identify the optimal patch test concentration for ascaridole, and to investigate the relationship between a positive reaction to ascaridole and a positive reaction to oxidized tea tree oil. PATIENTS/MATERIALS/METHODS: Three hundred and nineteen patients with eczema were patch tested with ascaridole 1%, 2%, and 5%, and 250 patients were patch tested with oxidized tea tree oil 5%. Readings were performed on D3 and D7 according to a patch test calibration protocol. RESULTS: With an increasing ascaridole test concentration, the frequency of positive reactions increased: ascaridole 1%, 1.4%; ascaridole 2%, 5.5%; and ascaridole 5%, 7.2%. However, the frequencies of irritant and doubtful reactions also increased, especially for ascaridole 5%. A positive reaction to ascaridole was related to a positive reaction to tea tree oil. CONCLUSIONS: This study is in support of ascaridole being a sensitizer. We recommend patch testing with ascaridole at 2%. The finding that every positive reaction to oxidized tea tree oil is accompanied by a positive reaction to ascaridole suggests that ascaridole might be a contact allergen in oxidized tea tree oil.

Enamel properties after tooth bleaching with hydrogen/carbamide peroxides in association with a CPP-ACP paste.

BACKGROUND: This study evaluated the impact of bleaching teeth using blends of a CPP-ACP paste (MI Paste; MI) and carbamide/hydrogen peroxides in different proportions on surface properties of bleached enamel. METHODS: Ninety bovine incisors were bleached with 7.5% hydrogen peroxide (HP), 16% carbamide peroxide (CP), MI and blends of HP or CP:MI at three proportions (1:1, 2:1, 1:2). Hardness and roughness were measured at baseline and after bleaching. Enamel morphology was evaluated by Scanning Electron Microscopy (SEM). The data were analyzed by two-way ANOVA for repeated measurements and Tukey's test. RESULTS: Most of the samples bleached with MI in combination with peroxides presented increased hardness and roughness which were associated to mineral deposition, as observed by SEM images. Blends with higher fractions of MI did not offer superior benefits. CONCLUSIONS: The use of a CPP-ACP paste mixed to carbamide/hydrogen peroxides can decrease adverse side-effects from tooth bleaching on an enamel surface.

The endoperoxide ascaridol shows strong differential cytotoxicity in nucleotide excision repair-deficient cells.

Targeting synthetic lethality in DNA repair pathways has become a promising anti-cancer strategy. However little is known about such interactions with regard to the nucleotide excision repair (NER) pathway. Therefore, cell lines with a defect in the NER genes ERCC6 or XPC and their normal counterparts were screened with 53 chemically defined phytochemicals isolated from plants used in traditional Chinese medicine for differential cytotoxic effects. The screening revealed 12 drugs that killed NER-deficient cells more efficiently than proficient cells. Five drugs were further analyzed for IC(50) values, effects on cell cycle distribution, and induction of DNA damage. Ascaridol was the most effective compound with a difference of >1000-fold in resistance between normal and NER-deficient cells (IC(50) values for cells with deficiency in ERCC6: 0.15µM, XPC: 0.18µM, and normal cells: >180µM). NER-deficiency combined with ascaridol treatment led to G2/M-phase arrest, an increased percentage of subG1 cells, and a substantially higher DNA damage induction. These results were confirmed in a second set of NER-deficient and -proficient cell lines with isogenic background. Finally, ascaridol was characterized for its ability to generate oxidative DNA damage. The drug led to a dose-dependent increase in intracellular levels of reactive oxygen species at cytotoxic concentrations, but only NER-deficient cells showed a strongly induced amount of 8-oxodG sites. In summary, ascaridol is a cytotoxic and DNA-damaging compound which generates intracellular reactive oxidative intermediates and which selectively affects NER-deficient cells. This could provide a new therapeutic option to treat cancer cells with mutations in NER genes.

Efficacy of a novel at-home bleaching technique with carbamide peroxides modified by CPP-ACP and its effect on the microhardness of bleached enamel.

This study was designed to evaluate in vitro the efficacy of a novel at-home bleaching technique using 10% or 16% carbamide peroxide modified by casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and its influence on the microhardness of bleached enamel. A total of 40 bovine incisors were divided into four groups (n=10) according to the bleaching agent used: 10% carbamide peroxide only; a blend of 10% carbamide peroxide and a CPP-ACP paste; 16% carbamide peroxide only; and a blend of 16% carbamide peroxide and a CPP-ACP paste. During the 14-day bleaching regimen, the samples were stored in artificial saliva. The Vickers microhardness and color of the teeth were assessed at baseline (T0) and immediately after the bleaching regimen (T14) using a microhardness tester and a spectrophotometer, respectively. The degree of color change was determined by the Commission Internationale de l'Eclariage (CIE) L*a*b* system (ΔE, ΔL*, Δa*, and Δb*) and Vita shade guide parameters. The data were analyzed by analysis of variance and the Tukey test (p<0.05). The teeth that were bleached with a blend of peroxide (10% or 16%) and the CPP-ACP paste presented increased microhardness values at T14 compared with T0, whereas the samples that were bleached with peroxide only did not show any differences in their microhardness values. All of the bleaching agents were effective at whitening the teeth and did not show a statistically significant difference using the CIEL*a*b* system (ΔE, ΔL*, Δa*, and Δb*) or the Vita shade guide parameters. The use of a CPP-ACP paste with carbamide peroxide bleaching agents increased the bleached enamel's microhardness and did not have an influence on whitening efficacy.

Chemical analysis of enamel and dentin following the application of three different at-home bleaching systems.

PURPOSE: To determine the change in the chemical composition of enamel and dentin as well as to evaluate the differences in surface texture of the same dental hard tissues following three at-home bleaching systems in vitro. METHODS: Sixty extracted intact human anterior teeth were used in this study. Thirty teeth were used as samples for enamel, and the buccal surfaces of the remaining 30 teeth were abraded and used as dentin samples. Prior to bleaching treatments, calcium (Ca), phosphorus (P), potassium (K), sodium (Na), magnesium (Mg), fluoride (F), and oxygen (O) levels of each sample were measured using an energy dispersive spectrometer. The teeth were then randomly allocated into three groups according to the bleaching system used, as follows: GI, 10% carbamide peroxide (CP); GII, 20% CP; GIII, and 35% CP. Following the bleaching treatments, Ca, P, K, Na, Mg, F, and O measurements were repeated. The surface configurations were examined using scanning electron microscopy (SEM). The data were analyzed using Wilcoxon signed rank and Kruskal-Wallis tests followed by the Dunn test. RESULTS: All three bleaching systems tested caused similar changes in the chemical composition of enamel and dentin. Bleaching systems decreased Ca and K, while F and O levels increased in enamel. In dentin, Ca, P, and K levels decreased; however, Na, F, and O levels increased. SEM observations revealed no deleterious effect on enamel and dentin. CONCLUSION: The use of home bleaching agents could affect the chemical composition of dental hard tissues, whereas the change in the chemical composition of enamel and dentin was not affected by the CP concentration of the bleaching systems used.

Mechanical, morphologic, and chemical effects of carbamide peroxide bleaching agents on human enamel in situ.

OBJECTIVES: To evaluate the morphologic, mechanical, and chemical effects of carbamide peroxide bleaching agents on human enamel in situ. METHOD AND MATERIALS: Enamel slabs from extracted human teeth were divided in two and mounted on contralateral sides of removable maxillary appliances fabricated for three participants. Soft vinyl trays were adapted intraorally over the arch; one side contained a bleaching agent, and the other served as a control. Vital bleaching was conducted in vivo three times with three different bleaching agents and with new enamel specimens each time. Tests of Knoop microhardness, scanning electronic microscopy (SEM), and energy dispersive x-ray (EDX) were performed and analyzed by ANOVA. RESULTS: No statistically significant differences were found between matched test and control specimens concerning microhardness values, morphology, or elemental content. CONCLUSIONS: Enamel surface showed no mechanical, morphologic, or chemical changes following bleaching in situ with three different carbamide peroxide agents.

Cerumen removal: comparison of cerumenolytic agents and effect on cognition among the elderly.

Cerumen impaction may affect hearing and decrease hearing acuity, thus decreasing cognitive functions among the elderly. The objective of this study was to compare the safety and the efficacy of three cerumenolytic agents and to assess the effect of cerumen removal on cognition. Thirty eight elderly subjects (mean age: 78 years, total 76 ears) were treated with either Auro®, Cerumol® or the newer CleanEars®, and the change in the degree of ear canal occlusion was examined after a week. In addition, a change in cognition following cerumen removal was evaluated using Raven's standard progressive matrices (RSPM) test. There was no difference regarding the eventual degree of occlusion between the three treatment groups. Only in the CleanEars® group a complete resolution of obstruction in both ears was achieved. A statistically significant difference between the RSPM score before and after the removal of cerumen was found. Using CleanEars® is as effective and safe as other agents and may be advantageous due to its spray application. Removal of cerumen significantly improves the well-being of elderly patients.

Influence of peroxide treatment on bovine enamel surface--cross-sectional analysis.

Carbamide peroxide and hydrogen peroxide are used as the main agents in vital tooth bleaching. In this study, the influence of peroxide treatment on cross-sectional morphology and mechanical property was investigated. A 3 x 5-mm window of enamel on the labial surface of a bovine tooth was exposed to immersion in 10% or 30% carbamide peroxide or hydrogen peroxide for 30 or 180 min. After immersion, the cross-sectional structure of each specimen was examined by nanoindentation and SEM. Nanohardness in the enamel showed a decrease at 2 microm below the surface, but none at 50 microm. High concentrations of peroxide caused erosion to a depth of 5 microm below the surface. In conclusion, decrease in nanohardness and change in morphology were limited to an area less than 50 microm below the surface, regardless of either concentration of peroxide or period of immersion.

Effect of different adhesive systems and laser treatment on the shear bond strength of bleached enamel.

PURPOSE: This study determined the shear bond strength of a nanohybrid composite resin to bleached enamel immediately or 15 days later using different adhesive systems and laser application. METHODS: One hundred and forty enamel specimens were prepared from human molar teeth and bleached either with 16% carbamide peroxide (CP) or 30% CP according to the manufacturer's (Vivastyle/Vivadent) recommendations. After bleaching treatments specimens were divided into two groups according to the treatment time of the adhesive procedures: immediately or 15 days after the bleaching treatments. The four groups were then divided into five subgroups due to the surface treatments: using a two-step self-etching adhesive (AdheSe, Ivoclar Vivadent G, Schaan, Liechtenstein) or a two-step etch and rinse adhesive (Excite, Ivoclar Vivadent G, Schaan, Liechtenstein) and application of laser prior to adhesive procedures or not. After adhesive procedures nanohybrid composite resin cylinders of 4 mm x 2 mm (Tetric Evo Ceram/Vivadent) were bonded to the enamel surfaces. All specimens were subjected to shear bond strength test after thermocycling and 24h of storage in water. Data were analyzed statistically. RESULTS: Mann-Whitney U-test analysis showed no significant difference in the mean bond strength values of enamel bleached with either 16% CP or 30% CP (p>0.05). There was no difference between the groups bonded immediately or 15 days after bleaching (p>0.05). Application of the etch and rinse adhesive after 15 days showed the highest bond strength values, whereas self-etching adhesive and laser application showed the lowest values in both bleaching treatments. CONCLUSIONS: The results suggested that following the bleaching treatments, the use of etch and rinse adhesive system may provide higher bond strengths than self-etching adhesive and laser application.

In vitro comparison of visual and computer-aided pre- and post-tooth shade determination using various home bleaching procedures.

STATEMENT OF PROBLEM: Due to inter- and intraexaminer differences, subjective evaluation of tooth color is deemed problematic. PURPOSE: The purpose of this study was to evaluate the efficacy of home bleaching products, and to compare visual and computer-aided tooth shade determinations when various agents were applied. MATERIAL AND METHODS: Human incisors (n=288) were stained (red wine, black tea) and allocated to 8 groups (n=36). Paint-on varnish (VivaStyle Paint On; 6% carbamide peroxide, CP) was used either for 1 x 20 min/d (VSP1), 2 x 20 min/d (VSP2), or 2 x 5 min/d (VSP25). Paint-on lacquer (Colgate Simply White, CSW; 5.9% hydrogen peroxide, HP) was applied for 2 x 30 min/d. Moreover, bleaching was performed using trays (VivaStyle, VS; 10% CP; 1 x 60 min/d, and Odol-med3 Beauty Kur, OBK; sodium chlorite; 2 x 10 min/d) or whitening strips (blend-a-med Whitestrips, BWS; 5.9% HP; 2 x 30 min/d). Water was used as control (1 x 60 min/d). Tooth shades were determined blindly (Chromascop Complete) after staining and 24 hours after final bleaching (visual and computer-aided assessment). Change in shade was analyzed using nonparametric methods (Kruskal-Wallis) and post hoc tests (Tukey and Kramer) (alpha=.05). RESULTS: Color changed significantly to lighter shades for all active agents. Analysis revealed significant differences among the control and all other groups, and among CSW/BWS versus VSP25/OBK, and VS versus OBK, for both evaluation methods. Additionally, significant differences were spectrophotometrically observed for VSP1/VSP2 versus BWS, and VSP2 versus OBK, with comparable reliabilities (0.995 at baseline; 0.994 after bleaching). CONCLUSIONS: Increased bleaching efficacy was observed with high peroxide concentrations; application time did not alter efficacy. Spectrophotometry was reproducible and objective. The 2 assessment methods matched 45.8% of the time.

A study in vitro to compare home and surgery vital bleaching techniques.

The aim of this study was to compare the effectiveness of three different types of commonly used bleaching techniques using an in-vitro model. Five groups of 10 tooth specimens were prepared and allocated randomly to treatment groups. The four treatment groups tested were a home tray bleaching product, an 'in surgery' tray bleaching product and an 'in surgery power bleaching' product for use with an activating light. The bleaching agent in the latter group was also tested without light activation to assess the additional benefit of the bleaching lamp. A placebo group treated with water was also included. Colour change was assessed using a Vita shade guide and an electronic chromometer. The mean change in shade guide units ranged from 10.9 to 13.2 units, with the 'in surgery' tray bleaching system producing the largest change. For the chromometer readings the mean change in tooth colour ranged from 3.6 to 25.6 units, with the night guard vital bleaching product producing the largest change. This study has demonstrated in vitro that all the different bleaching systems tested produced comparable changes in tooth colour.

Effect of thickener agents on dental enamel microhardness submitted to at-home bleaching.

Dental bleaching occurs due to an oxidation reaction between the bleaching agents and the macromolecules of pigments in the teeth. This reaction is unspecific and the peroxides can also affect the dental matrix causing mineral loss. On the other hand, recent studies have suggested that the thickener agent carbopol can also cause mineral loss. Thus, the objective of this study was to evaluate in vitro the effect of at-home dental bleaching on dental enamel microhardness after the use of bleaching agents with and without carbopol as a thickener agent. Bovine dental slabs with 3 x 3 x 3 mm were obtained, sequentially polished, and randomly divided into 4 groups according to the experimental treatment: G1: 2% carbopol; G2: 10% carbamide peroxide with carbopol; G3: carbowax; G4: 10% carbamide peroxide with poloxamer. Bleaching was performed daily for 4 weeks, immersed in artificial saliva. Enamel microhardness values were obtained before the treatment (T0) and 7 (T1), 14 (T2), 21 (T3), 28 (T4), and 42 (T5) days after the beginning of the treatment. ANOVA and Tukey's test revealed statistically significant differences only for the factor Time (F = 5.48; p < 0.01). All bleaching and thickener agents caused no alterations on the enamel microhardness.

Surface microhardness of enamel after different home bleaching procedures.

OBJECTIVES: The purpose of this study was to evaluate the influence of different home bleaching procedures on surface microhardness of human enamel. METHODS: Among eight groups 192 incisors were distributed. The facial surface of each incisor was polished and baseline hardness of enamel (m0; Knoop) was assessed with a load of 1N for 30s. Subsequently, the enamel was treated for 14 days with the bleaching agent: groups 1, 2 and 4 Viva Style Paint on, 8% carbamide peroxide (CP) 1x20min, 2x20min and 2x5min; group 3 Colgate Simply White, 5.9% hydrogen peroxide (HP), 2x30min; group 5 Viva Style 10% CP 1x1h; group 6 Blend-a-med White Strips, 5.9% HP 2x30min; group 7 Odol-med3 Beauty-Kur, sodium chlorite 2x10min; group 8 control, running water 1x1h. Hardness was reassessed after the last bleaching treatment (m1) and after 6 weeks storage in artificial saliva (m2). RESULTS: Changes in microhardness were as follows (m0-m1): (1) -2.3 (+/-20.3); (2) -8.9 (+/-27.2); (3) 63.4 (+/-56.3); (4) 9.6 (+/-30.1); (5) 12.8 (+/-62.6); (6) 92.2 (+/-50.2); (7) 158.4 (+/-59.7); (8) 10.6 (+/-38.5). Statistical analysis showed that hardness values were significantly (p< or =0.0005; Wilcoxon test) reduced in groups 3, 6, and 7 (m1) and in group 7 (m2). SIGNIFICANCE: Both type of bleaching agent and concentration have a significant influence on the microhardness of enamel. The most critical bleaching agent seems to be the one containing sodium chlorite in combination with citric acid.

Effect of thickener agents on dental enamel microhardness submitted to at-home bleaching

Dental bleaching occurs due to an oxidation reaction between the bleaching agents and the macromolecules of pigments in the teeth. This reaction is unspecific and the peroxides can also affect the dental matrix causing mineral loss. On the other hand, recent studies have suggested that the thickener agent carbopol can also cause mineral loss. Thus, the objective of this study was to evaluate in vitro the effect of at-home dental bleaching on dental enamel microhardness after the use of bleaching agents with and without carbopol as a thickener agent. Bovine dental slabs with 3 x 3 x 3 mm were obtained, sequentially polished, and randomly divided into 4 groups according to the experimental treatment: G1: 2 percent carbopol; G2: 10 percent carbamide peroxide with carbopol; G3: carbowax; G4: 10 percent carbamide peroxide with poloxamer. Bleaching was performed daily for 4 weeks, immersed in artificial saliva. Enamel microhardness values were obtained before the treatment (T0) and 7 (T1), 14 (T2), 21 (T3), 28 (T4), and 42 (T5) days after the beginning of the treatment. ANOVA and Tukey's test revealed statistically significant differences only for the factor Time (F = 5.48; p < 0.01). All bleaching and thickener agents caused no alterations on the enamel microhardness.

O clareamento dental ocorre devido a uma reação de oxidação entre o agente clareador e as macromoléculas de pigmentos presentes nos dentes. Esta reação é inespecífica e o peróxido pode agir na matriz dental causando perdas de mineral. Por outro lado, estudos recentes sugerem que o agente espessante carbopol também pode causar perda mineral. Assim, o objetivo deste trabalho foi avaliar in vitro o efeito do clareamento caseiro sobre a microdureza do esmalte após o uso de agentes clareadores com e sem carbopol como espessante. Fragmentos de esmalte bovino de 3 x 3 x 3 mm foram obtidos, polidos seqüencialmente e aleatoriamente divididos em 4 grupos de acordo com o tratamento experimental: G1: carbopol a 2 por cento; G2: peróxido de carbamida a 10 por cento com carbopol; G3: carbowax; G4: peróxido de carbamida a 10 por cento com poloxamer. O clareamento foi realizado diariamente por 4 semanas em saliva artificial. A microdureza do esmalte foi avaliada antes (T0) e após 7 (T1), 14 (T2), 21 (T3), 28 (T4), e 42 (T5) dias do início do tratamento. A ANOVA e o teste de Tukey revelaram diferenças estatísticas significantes somente para o fator Tempo (F = 5,48; p < 0,01). Os agentes clareadores e espessantes não causaram alterações na microdureza do esmalte.

Tooth bleaching by different concentrations of carbamide peroxide and hydrogen peroxide whitening strips: an in vitro study.

OBJECTIVE: To investigate the tooth whitening effects of various concentrations of carbamide peroxide (CP) gels and 6% hydrogen peroxide (HP) whitening strips used on an intrinsic, in vitro stain model in a simulated home-applied bleaching protocol. METHOD: Extracted third molars were sectioned and stained to Vita shade C4 using a standardized tea solution. Stained specimens were then bleached with 10, 15, 20, 22, and 30% CP gels applied in custom-made trays for 8-hour sessions for 14 days. A 6% HP whitening strip product was also tested in a regimen of twice-daily 30-minute treatments for 14 days. Shades were assessed at baseline and at 2, 5, 7, 10, and 14 days of treatment using a shade guide (SG) and a shade vision system (SVS), recorded as shade guide unit (SGU) changes from baseline, and CIE L*a*b* recordings using a chromometer. RESULTS: By day 14, all CP treatments resulted in at least 12 SGU improvements by SG and SVS methods: the HP treatment mean was just less than 12 SGU. With the chromometer, the CP improvements ranged from approximately 19 to 28 units and 16 units for the HP whitening strips. Observationally, by SG and SVS, CP treatments achieved the maximum improvement (12-13 SGU) at different time points: day 5 for 30% CP, day 10 for 22% CP, and day 14 for the other three treatments. SG and SVS data were virtually binary, switching from 0 to scores of 9 or above as bleaching progressed. The differences between the six treatments in the mean day to achieve a positive SG or SVS score (9 or more units) approached significance. For each of the SG, SVS, and L*a*b* scores, the dose-response correlation with CP concentration was significant at one or more assessment times. SG and SVS showed extremely strong agreement in detecting change and substantial agreement with L*a*b*. CONCLUSION: This in vitro study supports the limited data available from the very few available randomized controlled clinical trials indicating that CP and HP home-use bleaching systems can achieve considerable tooth whitening outcomes, albeit at different rates, which appear to be concentration dependent. CLINICAL SIGNIFICANCE: There is a clear significant relationship for both concentration and duration of exposure for CP bleaching agents. The final shade change is independent of the concentration of bleaching agent, with time as the dominant variable. Higher concentrations of CP that have not been investigated previously may be a treatment option for esthetic improvement of shade where time is at a premium, but caution must be exercised in view of the possible increased incidence of sensitivity.

Effect of bleaching on fracture toughness of composite-dentin bonds.

PURPOSE: The effect of carbamide peroxide concentration and length of exposure on fracture toughness (KIC) of existing composite-dentin interfaces was assessed using the notchless triangular prism (NTP) specimen KIC test. MATERIALS AND METHODS: Freshly extracted human molars and premolars were wet ground on 600-grit SiC to obtain 4 x 4 x 4 x 4 mm triangular prisms, exposing buccal or lingual dentin. Dentin surfaces were bonded using a resin composite (Z-250, 3M) and SingleBond dentin bonding system (3M) to obtain 180 8-mm-long dentin-composite NTP specimens. The bonding system was applied using the "wet-bonding" technique. The bonded specimens were randomly assigned to 20 groups. The effect of exposure to three control solutions (tap water, Carbopol, and Carbopol-urea) and to four concentrations (11%, 13%, 16%, 21%) of carbamide peroxide (Perfecta, Premier) was assessed. Testing was conducted after 1, 2, and 3 weeks representing a cumulative exposure of 14, 42, and 70 h. The maximum force recorded before fracture was used to calculate KIC. The data were statistically analysed using two-factor ANOVA followed by one-way ANOVA and Bonferroni multiple means comparisons. Selected fractured surfaces were characterized using SEM. RESULTS: Data analysis revealed that cumulative exposure to bleaching agent for 70 h significantly (p < 0.01) decreased the interfacial KIC, regardless of concentration. For the 16% and 21% concentrations, a significant reduction was observed after 42 h. CONCLUSION: The results suggest that bleaching could adversely affect the interfacial fracture toughness of dentin-resin composite adhesive interfaces.

[Topical administration of an hyperoxygenated fatty acid compound. Preventive and curative effects on pressure ulcer]. / Aplicación tópica de un compuesto de ácidos grasos hiperoxigenados. Efectos preventivos y curativos en úlceras por presión.

INTRODUCTION: Hyper-oxygenized acidic fats are a very useful topical use product for preventing pressure ulcers and to treat stage I pressure ulcers. Mepentol is a hyper-oxygenized acidic fats product (linoleic acid, gamma linolenic acid, oleic acid, palmitic acid, stearic acid, palmitoleic acid, arachidonic acid and eicosenoic acid) with extracts of Equisetum Avrense and Hypericum Perforatum. It works in three main facets: improve as is possible the epidermis's resistance, repair the damage to the epidermis produced by a prolonged pressure, and restore capillary circulation and counter arrest the effect of oxygen radicals produced during reactive hyperemia which are caused by periods of prolonged pressure. The exclusive formula, based on hyperoxygenized acidic fats and the above referred plant extracts, gives to Mepentol a demonstrated effectiveness, and also special features, like speed of action, great speed of topical absorption and a peculiar fragrance. PATIENTS, MATERIAL AND METHOD: In order to evaluate the tissue level effect of Mepentol, we carried out an experimental research project based on two different objectives: determine the effect at capillary circulation level in heels of healthy volunteers and in patients under risk of developing pressure ulcers, a well as in the treatment of stage I pressure ulcers in patients under high risk of developing pressure ulcers. To do so, the authors determined the capillary blood flow by means of a Doppler laser flow meter. RESULTS: After the application of a hyper-oxygenized acidic fats product, the authors noted an increase of 122.29 +/- 68.74% in flow units related to base values. The authors also observed an increase in microcirculation in heels of patients under high risk of developing pressure ulcers, as well as those who suffer from stage I lesions. These increases remain constant over long periods of time. COMMENTARY: Based on the tests carried out, Mepentol shows an undoubtable effect which improves local circulation in zones under risk of developing pressure ulcers as well as for stage I lesions; this supports the use of this product as a preventive measure against pressure ulcers and as treatment for stage I lesions.