Effect of resistance training combined with ß-glucan ingestion on bone of ovariectomized mice.

OBJECTIVE: This study aimed to evaluate the effects of resistance training (RT) combined with prebiotic ß-glucan (BG) ingestion (Saccharomyces cerevisiae) in ovariectomized (OVX) mice. METHODS: Forty-eight mice were divided into six treatments: SHAM group and five OVX groups treated with saline (SAL), alendronate (ALE) (0.1 mg/kg), BG (62.5 mg/kg), RT (climbing a ladder with load) and the combination of BG + RT. All treatments were performed three times per week for 8 weeks starting 38 days after ovariectomy. RESULTS: OVX effectiveness was confirmed by a reduction in uterus mass (p < 0.05). Femur weight was higher in the SHAM group, followed by the ALE and RT groups with intermediate values and the BG + RT, BG and SAL groups with the lowest values (p < 0.05). The bone mineral density (BMDDEXA) results were higher for the SHAM and RT groups compared to the other groups (p < 0.05). RT provided similar bone mass and resistance to fracture to ALE and SHAM. We found a similar number of osteocytes in the RT and SHAM groups, which was significantly higher than that found in animals receiving BG (p < 0.05). The BG + RT combination increased calcium bone concentration. CONCLUSION: RT promoted benefits on bone health in the OVX model, which were not complemented by the consumption of BG.

Insights into the antiviral activity of phospholipases A2 (PLA2s) from snake venoms.

Viruses are associated with several human diseases that infect a large number of individuals, hence directly affecting global health and economy. Owing to the lack of efficient vaccines, antiviral therapy and emerging resistance strains, many viruses are considered as a potential threat to public health. Therefore, researches have been developed to identify new drug candidates for future treatments. Among them, antiviral research based on natural molecules is a promising approach. Phospholipases A2 (PLA2s) isolated from snake venom have shown significant antiviral activity against some viruses such as Dengue virus, Human Immunodeficiency virus, Hepatitis C virus and Yellow fever virus, and have emerged as an attractive alternative strategy for the development of novel antiviral therapy. Thus, this review provides an overview of remarkable findings involving PLA2s from snake venom that possess antiviral activity, and discusses the mechanisms of action mediated by PLA2s against different stages of virus replication cycle. Additionally, molecular docking simulations were performed by interacting between phospholipids from Dengue virus envelope and PLA2s from Bothrops asper snake venom. Studies on snake venom PLA2s highlight the potential use of these proteins for the development of broad-spectrum antiviral drugs.

Evaluation of Cameriere and Willems age estimation methods in panoramic radiographs of Brazilian children.

The importance of age estimation in the forensic field is inherent to the process of establishing the biological profile of children, sub-adults and adults. The established profile might be useful for the identification of deceased victims or living individuals when it comes to age of legal interest. In parallel, age estimation is also investigated for clinical purposes, especially for the diagnosis of dental and bone maturation. Several studies were developed to provide accurate age estimation methods based on skeletal and dental development. This study aimed to apply and compare Cameriere's and Willems' methods for dental age estimation in a Brazilian sample. Two examiners performed image analysis and method application in 180 panoramic radiographs of Brazilian children aged 6-14 years old. The ages estimated with both methods revealed a good correlation with the chronological ages of Brazilian boys and girls. Cameriere's method showed a slight underestimation of 0.05 years for girls and 0.03 for boys. Willems' method, on the other hand, showed an overestimation of -0.47 years for girls and -0.39 for boys. Better age estimates were obtained combining the outcomes of both methods. In practice, Cameriere's and Willems' methods reached reliable outcomes and could be applied for dental age estimation purposes.

Leptin actions through the nitrergic system to modulate the hypothalamic expression of the kiss1 mRNA in the female rat.

Gonadotrophin-releasing hormone (GnRH) is the main controller of the reproductive axis and stimulates the synthesis and secretion of gonadotrophins. Estrogen is the main peripheral factor controlling GnRH secretion, and this action is mainly mediated by the transsynaptic pathway through nitric oxide, kisspeptin, leptin, among other factors. Kisspeptin is the most potent factor known to induce GnRH release. Nitric oxide and leptin also promote GnRH release; however, neurons expressing GnRH do not express the leptin receptor (OB-R). Leptin seems to modulate the expression of genes and proteins involved in the kisspeptin system. However, few kisspeptin-synthesizing cells in the arcuate nucleus (ARC) and few cells, if any, in the preoptic area (POA) express OB-R; this indicates an indirect mechanism of leptin action on kisspeptin. Nitric oxide is an important intermediate in the actions of leptin in the central nervous system. Thus, this work aimed to verify the numbers of nNOS cells were activated by leptin in different hypothalamic areas; the modulatory effects of the nitrergic system on the kisspeptin system; and the indirect regulatory effect of leptin on the kisspeptin system via nitric oxide. Ovariectomized rats were treated with estrogen or a vehicle and received an intracerebroventricular (i.c.v.) injection of a nitric oxide donor, leptin or neuronal nitric oxide synthase (nNOS) enzyme inhibitor. Thirty minutes after the injection, the animals were decapitated. Leptin acts directly on nitrergic neurons in different hypothalamic regions, and the effects on the ventral premammillary nucleus (PMV) and ventral dorsomedial hypothalamus (vDMH) are enhanced. The use of a nitric oxide donor or the administration of leptin stimulates the expression of the kisspeptin mRNA in the ARC of animals with or without estrogenic action; however, these changes are not observed in the POA. In addition, the action of leptin on the expression of the kisspeptin mRNA in the ARC is blocked by a nitric oxide synthesis inhibitor. We concluded that the effects of leptin on the central nervous system are at least partially mediated by the nitrergic system. Also, nitric oxide acts on the kisspeptin system by modulating the expression of the kisspeptin mRNA, and leptin at least partially modulates the kisspeptin system through the nitrergic system, particularly in the ARC.

Alterations in mtDNA, gastric carcinogenesis and early diagnosis.

Gastric cancer remains one of the most prevalent cancers in the world. Due to this, efforts are being made to improve the diagnosis of this neoplasm and the search for molecular markers that may be involved in its genesis. Within this perspective, the mitochondrial DNA is considered as a potential candidate, since it has several well documented changes and is readily accessible. However, numerous alterations have been reported in mtDNA, not facilitating the visualization of which alterations and molecular markers are truly involved with gastric carcinogenesis. This review presents a compilation of the main known changes relating mtDNA to gastric cancer and their clinical significance.

Strain induced polarization chaos in a solitary VCSEL.

Physical curiosity at the beginning, optical chaos is now attracting increasing interest in various technological areas such as detection and ranging or secure communications, to name but a few. However, the complexity of optical chaos generators still significantly hinders their development. In this context, the generation of chaotic polarization fluctuations in a single laser diode has proven to be a significant step forward, despite being observed solely for quantum-dot vertical-cavity surface-emitting lasers (VCSELs). Here, we demonstrate experimentally that a similar polarization dynamics can be consistently obtained in quantum-well VCSELs. Indeed, by introducing anisotropic strain in the laser cavity, we successfully triggered the desired chaotic dynamics. The simplicity of the proposed approach, based on low-cost and easily available components including off-the-shelf VCSELs, paves the way to the wide spread use of solitary VCSELs for chaos-based applications.

Safe therapeutics of murine melanoma model using a novel antineoplasic, the partially methylated mannogalactan from Pleurotus eryngii.

A heteropolysaccharide was isolated by cold aqueous extraction from edible mushroom Pleurotus eryngii ("King Oyster") basidiocarps and its biological properties were evaluated. Structural assignments were carried out using mono- and bidimensional NMR spectroscopy, monosaccharide composition, and methylation analyses. A mannogalactan having a main chain of (1→6)-linked α-d-galactopyranosyl and 3-O-methyl-α-d-galactopyranosyl residues, both partially substituted at OH-2 by ß-d-Manp (MG-Pe) single-unit was found. Biological effects of mannogalactan from P. eryngii (MG-Pe) were tested against murine melanoma cells. MG-Pe was non-cytotoxic, but reduced in vitro melanoma cells invasion. Also, 50mg/kg MG-Pe administration to melanoma-bearing C57BL/6 mice up to 10days decreased in 60% the tumor volume compared to control. Additionally, no changes were observed when biochemical profile, complete blood cells count (CBC), organs, and body weight were analyzed. Mg-Pe was shown to be a promising anti-melanoma molecule capable of switching melanoma cells to a non-invasive phenotype with no toxicity to melanoma-bearing mice.

The type-1 cannabinoid receptor modulates the hydroelectrolytic balance independently of the energy homeostasis during salt load.

Hydroelectrolytic imbalances, such as saline load (SL), trigger behavioral and neuroendocrine responses, such as thirst, hypophagia, vasopressin (AVP) and oxytocin (OT) release and hypothalamus­pituitary­adrenal (HPA) axis activation. To investigate the participation of the type-1 cannabinoid receptor (CB1R) in these homeostatic mechanisms,male adult Wistar rats were subjected to SL (0.3MNaCl) for four days. SL induced not only increases in the water intake and plasma levels of AVP, OT and corticosterone, as previously described, but also increases in CB1R expression in the lamina terminalis, which integrates sensory afferents, aswell as in the hypothalamus, the main integrative and effector area controlling hydroelectrolytic homeostasis. A more detailed analysis revealed that CB1R-positive terminals are in close apposition with not only axons but also dendrites and secretory granules of magnocellular neurons, particularly vasopressinergic cells. In satiated and euhydrated animals, the intracerebroventricular administration of the CB1R selective agonist ACEA (0.1 µg/5 µL) promoted hyperphagia, but this treatment did not reverse the hyperosmolality-induced hypophagia in the SL group. Furthermore, ACEA pretreatment potentiated water intake in the SL animals during rehydration as well as enhanced the corticosterone release and prevented the increase in AVP and OT secretion induced by SL. The same parameters were not changed by ACEA in the animals whose daily food intake was matched to that of the SL group (Pair-Fed). These data indicate that CB1Rs modulate the hydroelectrolytic balance independently of the food intake during sustained hyperosmolality and hypovolemia.

Thymidylate synthase and methylenetetrahy-drofolate reductase gene polymorphisms and gastric cancer susceptibility in a population of Northern Brazil.

The folate metabolic pathway, which is involved in DNA synthesis and methylation, is associated with individual susceptibility to several diseases, including gastric tumors. In this study, we investigated four polymorphisms [thymidylate synthase enhancer region, single nucleotide polymorphism thymidylate synthase 5' (TS5'), TS3' untranslated region, and methylenetetrahydrofolate reductase (MTHFR) 677C> T] in 2 genes related to the folate pathway, TS and MTHFR, and their possible association with the risk gastric cancer development in a population from Pará state, Brazil. For the TS enhancer region, TS3' untranslated region, and single nucleotide polymorphism TS5' polymorphisms, no significant results were obtained. For the MTHFR 677C>T polymorphism, TT genotype carriers had a higher risk of developing tumors in the antrum (P = 0.19 vs CC and P = 0.02 vs CT) and intestine (odds ratio = 4.18, 95% confidence interval = 0.66-26.41; P = 0.252 vs CC and odds ratio = 2.25, 95% confidence interval = 0.32-15.75; P = 0.725 vs CT). Those carrying at least 1 T allele had an increased risk of lymph node metastasis (odds ratio = 3.00, 95% confidence interval = 0.88-10.12; P = 0.133). Our results suggest that polymorphisms in MTHFR affect the susceptibility to gastric tumors in the Brazilian population and may be a factor causing poor prognosis in such patients.

Endophytic bacteria from Piper tuberculatum Jacq.: isolation, molecular characterization, and in vitro screening for the control of Fusarium solani f. sp piperis, the causal agent of root rot disease in black pepper (Piper nigrum L.).

Endophytic bacteria have been found to colonize internal tissues in many different plants, where they can have several beneficial effects, including defense against pathogens. In this study, we aimed to identify endophytic bacteria associated with roots of the tropical piperaceae Piper tuberculatum, which is known for its resistance to infection by Fusarium solani f. sp piperis, the causal agent of black pepper (Piper nigrum) root rot disease in the Amazon region. Based on 16S rRNA gene sequence analysis, we isolated endophytes belonging to 13 genera: Bacillus, Paenibacillus, Pseudomonas, Enterobacter, Rhizobium, Sinorhizobium, Agrobacterium, Ralstonia, Serratia, Cupriavidus, Mitsuaria, Pantoea, and Staphylococcus. The results showed that 56.52% of isolates were associated with the phylum Proteobacteria, which comprised α, ß, and γ classes. Other bacteria were related to the phylum Firmicutes, including Bacillus, which was the most abundant genus among all isolates. Antagonistic assays revealed that Pt12 and Pt13 isolates, identified as Pseudomonas putida and Pseudomonas sp, respectively, were able to inhibit F. solani f. sp piperis growth in vitro. We describe, for the first time, the molecular identification of 23 endophytic bacteria from P. tuberculatum, among which two Pseudomonas species have the potential to control the pathogen responsible for root rot disease in black pepper in the Amazon region.

Estrogen-dependent post-translational change in the nitric oxide system may mediate the leptin action on LH and prolactin secretion.

Gonadotrophin-releasing hormone (GnRH) neurons do not express the leptin receptor (OB-R) in the medial preoptic area (MPOA) and the medial basal hypothalamus (MBH). We assessed whether the effect of leptin on the secretion of luteinizing hormone (LH), follicle stimulating hormone (FSH) and prolactin (PRL) in proestrus could be mediated by nitric oxide (NO) under estrogen modulation. Female rats were treated with an estrogen antagonist (tamoxifen s.c. 3mg/rat) or vehicle during metestrus and diestrus. At proestrus, they received leptin (3 or 10 µg/µl) or intracerebroventricular saline at 11:00 am and were decapitated at 5:00 pm. The following were analyzed in this work: plasma LH, FSH and PRL levels (radioimmunoassay); neuronal NO-synthase (nNOS) and OB-R transcription (RT-PCR); nNOS and phosphorylated nNOS (pnNOS) translation levels (western blotting); and pSTAT3 immunoreactivity. Tamoxifen reduced the plasma LH and PRL levels and decreased the nNOS mRNA and pnNOS expression in the MPOA. Three micrograms of leptin increased the LH secretion and pnNOS protein levels in the MPOA and MBH. Ten micrograms of leptin decreased the transcription, translation and phosphorylation of nNOS in the MPOA. In the MBH, 10 µg of leptin increased the protein expression of nNOS but not the mRNA expression neither pnNOS protein. Tamoxifen did not change either the mRNA or protein expression of nNOS or the phosphorylation of nNOS but decreased the number of cells that contained pSTAT3 immunoreactivity in both areas. In conclusion, the stimulatory effect of leptin on the secretion of LH and PRL on the afternoon of proestrus may be mediated by estrogen-dependent post-translational changes in the nNOS in the MPOA and MBH.

Modulation of the activity of vasopressinergic neurons by estrogen in rats refed with normal or sodium-free food after fasting.

Feeding increases plasma osmolality and ovarian steroids may influence the balance of fluids. Vasopressin (AVP) neurons in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) express estrogen receptor type ß (ERß), but not estrogen receptor type α (ERα). The circumventricular organs express ERα and project efferent fibers to the PVN and SON. Our aim was to assess whether interactions exist between food state-related osmolality changes and the action of estrogen on AVP neuron activity and estrogen receptor expression. We assessed plasma osmolality and AVP levels; fos-coded protein (FOS)- and AVP-immunoreactivity (-IR) and FOS-IR and ERα-IR in the median preoptic nucleus (MnPO) and organ vasculosum lamina terminalis (OVLT) in estrogen-primed and unprimed ovariectomized rats under the provision of ad libitum food, 48h of fasting, and subsequent refeeding with standard chow or sodium-free food. Refeeding with standard chow increased plasma osmolality and AVP as well as the co-expression of FOS-IR/AVP-IR in the PVN and SON. These responses were not altered by estrogen, with the exception of the decreases in FOS-IR/AVP-IR in the lateral PVN. During refeeding, estrogen modulates only a subpopulation of AVP neurons in the lateral PVN. FOS-ERα co-expression in the ventral median preoptic nucleus (vMnPO) was reduced by estrogen and increased after refeeding with standard chow following fasting. It appears that estrogen may indirectly modulate the activity of AVP neurons, which are involved in the mechanism affected by hyperosmolality-induced refeeding after fasting. This indirect action of estrogen can be at least in part via ERα in the vMnPO.

Preheating impact on the degree of conversion and water sorption/solubility of selected single-bottle adhesive systems.

OBJECTIVE: This study evaluated the degree of conversion (DC) and the water sorption/solubility of preheated single-bottle adhesive systems. METHODS AND MATERIALS: Five adhesive systems were tested: Adper Easy One and Adper Single Bond 2 (3M ESPE), Excite and Tetric N-Bond (Ivoclar/Vivadent), and XP Bond (Dentsply/Caulk). After storage for two hours at 25°C or 60°C, 50 samples (n=5) were prepared for all adhesive systems and stored dry in lightproof containers at 37°C for 24 hours. Fourier transform infrared/attenuated total reflectance spectroscopy was used to evaluate the DC, and water sorption/solubility was measured by means of mass loss and gain after water storage. The data were analyzed by two-way analysis of variance followed by Tukey's test (p<0.05). RESULTS: Preheated adhesive systems showed statistically significantly higher DC than those kept at 25°C. Except for XP Bond, preheated adhesive systems presented statistically significantly lower water sorption/solubility means. CONCLUSIONS: Preheating improved the DC for all tested adhesive systems. Also, it promoted a decrease of water sorption/solubility, except for the XP Bond adhesive system.

Dual-cured etch-and-rinse adhesive systems increase the bond durability of direct coronal dentin restorations.

This study aimed to evaluate the bond durability of dentin restorations bonded with light- or dual-cured etch-and-rinse adhesive systems. A three-step adhesive system (Scotchbond Multipurpose Plus), an acetone-based two-step adhesive system (Prime & Bond 2.1), and an ethanol-based two-step adhesive system (Excite) were tested. Both the light- and the dual-cured versions were evaluated. High C-factor dentin cavities were prepared on 120 bovine incisors, which were then restored with resin composite (n=10). The samples were stored in water for 24 hours, and half of them were subjected to additional degradation with 10% NaOCl for five hours. The push-out bond strength test was performed in a universal testing machine until failure. Failure modes were evaluated by scanning electron microscopy. Data were analyzed by three-way analysis of variance and Tukey tests (p<0.05). The dual-cured adhesive system presented a higher immediate bond strength and durability than those that were light cured. The three-step adhesive system produced the highest values, whereas the acetone-based adhesive system produced the lowest result. Therefore, the use of dual-cured etch-and-rinse adhesive systems can induce increased bond durability to direct coronal dentin restorations.

Transitory activation of the central and ovarian norepinephrine systems during cold stress-induced polycystic ovary in rats.

Cold stress-induced ovarian sympathetic activation is associated with the development of ovarian cysts in rats. Although we have hypothesised that polycystic ovary (PCO) features induced by cold stress, as prevented by lesion of the noradrenergic nucleus locus coeruleus (LC), were a result of the increased activity of the ovarian norepinephrine (NE) system, this was not evident after 8 weeks of stress. In the present study, we investigated the temporal changes in LC and ovarian NE activities and steroid secretion in rats exposed to single (SS) or repeated (RS) cold stress. SS and 4 week (4W)-RS but not 8 week (8W)-RS increased c-Fos expression in the LC and ovarian NE release. Plasma oestradiol, testosterone and progesterone levels tended to increase in 4W-RS and were elevated in 8W-RS rats, which displayed PCO morphology. ß-adrenergic receptor agonist increased steroid hormone release from the ovary of unstressed (US) but not from 8W-RS rats. To determine whether increased activity of noradrenergic system during the initial 4 weeks of RS would be sufficient to promote PCO, rats were exposed to 4 weeks of cold stress and kept in ambient temperature for the next 4 weeks (4W-RS/4W-US). Accordingly, PCO morphology, increased steroid secretion and decreased ovulation rate were found in 4W-RS/4W-US rats, strengthening the hypothesis that the initial increase in NE release triggers the development of PCO. The correlated activity of LC neurones and ovarian noradrenergic terminals and the induction of PCO in 4W-RS/4W-US rats provide functional evidence for a major role of NE in disrupting follicular development and causing the long-lasting endocrine abnormalities found in stress-induced PCO.

Glial cell activity is maintained during prolonged inflammatory challenge in rats

We evaluated the expression of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), ionized calcium binding adaptor protein-1 (Iba-1), and ferritin in rats after single or repeated lipopolysaccharide (LPS) treatment, which is known to induce endotoxin tolerance and glial activation. Male Wistar rats (200-250 g) received ip injections of LPS (100 µg/kg) or saline for 6 days: 6 saline (N = 5), 5 saline + 1 LPS (N = 6) and 6 LPS (N = 6). After the sixth injection, the rats were perfused and the brains were collected for immunohistochemistry. After a single LPS dose, the number of GFAP-positive cells increased in the hypothalamic arcuate nucleus (ARC; 1 LPS: 35.6 ± 1.4 vs control: 23.1 ± 2.5) and hippocampus (1 LPS: 165.0 ± 3.0 vs control: 137.5 ± 2.5), and interestingly, 6 LPS injections further increased GFAP expression in these regions (ARC = 52.5 ± 4.3; hippocampus = 182.2 ± 4.1). We found a higher GS expression only in the hippocampus of the 6 LPS injections group (56.6 ± 0.8 vs 46.7 ± 1.9). Ferritin-positive cells increased similarly in the hippocampus of rats treated with a single (49.2 ± 1.7 vs 28.1 ± 1.9) or repeated (47.6 ± 1.1 vs 28.1 ± 1.9) LPS dose. Single LPS enhanced Iba-1 in the paraventricular nucleus (PVN: 92.8 ± 4.1 vs 65.2 ± 2.2) and hippocampus (99.4 ± 4.4 vs 73.8 ± 2.1), but had no effect in the retrochiasmatic nucleus (RCA) and ARC. Interestingly, 6 LPS increased the Iba-1 expression in these hypothalamic and hippocampal regions (RCA: 57.8 ± 4.6 vs 36.6 ± 2.2; ARC: 62.4 ± 6.0 vs 37.0 ± 2.2; PVN: 100.7 ± 4.4 vs 65.2 ± 2.2; hippocampus: 123.0 ± 3.8 vs 73.8 ± 2.1). The results suggest that repeated LPS treatment stimulates the expression of glial activation markers, protecting neuronal activity during prolonged inflammatory challenges.

Glial cell activity is maintained during prolonged inflammatory challenge in rats.

We evaluated the expression of glial fibrillary acidic protein (GFAP), glutamine synthetase (GS), ionized calcium binding adaptor protein-1 (Iba-1), and ferritin in rats after single or repeated lipopolysaccharide (LPS) treatment, which is known to induce endotoxin tolerance and glial activation. Male Wistar rats (200-250 g) received ip injections of LPS (100 µg/kg) or saline for 6 days: 6 saline (N = 5), 5 saline + 1 LPS (N = 6) and 6 LPS (N = 6). After the sixth injection, the rats were perfused and the brains were collected for immunohistochemistry. After a single LPS dose, the number of GFAP-positive cells increased in the hypothalamic arcuate nucleus (ARC; 1 LPS: 35.6 ± 1.4 vs control: 23.1 ± 2.5) and hippocampus (1 LPS: 165.0 ± 3.0 vs control: 137.5 ± 2.5), and interestingly, 6 LPS injections further increased GFAP expression in these regions (ARC = 52.5 ± 4.3; hippocampus = 182.2 ± 4.1). We found a higher GS expression only in the hippocampus of the 6 LPS injections group (56.6 ± 0.8 vs 46.7 ± 1.9). Ferritin-positive cells increased similarly in the hippocampus of rats treated with a single (49.2 ± 1.7 vs 28.1 ± 1.9) or repeated (47.6 ± 1.1 vs 28.1 ± 1.9) LPS dose. Single LPS enhanced Iba-1 in the paraventricular nucleus (PVN: 92.8 ± 4.1 vs 65.2 ± 2.2) and hippocampus (99.4 ± 4.4 vs 73.8 ± 2.1), but had no effect in the retrochiasmatic nucleus (RCA) and ARC. Interestingly, 6 LPS increased the Iba-1 expression in these hypothalamic and hippocampal regions (RCA: 57.8 ± 4.6 vs 36.6 ± 2.2; ARC: 62.4 ± 6.0 vs 37.0 ± 2.2; PVN: 100.7 ± 4.4 vs 65.2 ± 2.2; hippocampus: 123.0 ± 3.8 vs 73.8 ± 2.1). The results suggest that repeated LPS treatment stimulates the expression of glial activation markers, protecting neuronal activity during prolonged inflammatory challenges.

Tooth whitening with hydrogen/carbamide peroxides in association with a CPP-ACP paste at different proportions.

BACKGROUND: Different enhanced peroxide formulations have been developed to overcome mineral loss during tooth whitening. This study investigated the impact on tooth whitening from combining a CPP-ACP paste with home peroxide agents at several proportions. METHODS: Ninety bovine incisors were randomly allocated into nine groups (n = 10) and exposed to 7.5% hydrogen peroxide (HP), 16% carbamide peroxide (CP), a CPP-ACP paste (Tooth Mousse/MI Paste, GC Corporation, Tokyo, Japan) and blends of HP/CP:MI at three proportions (1:1, 2:1 and 1:2). Tooth whitening was performed for 14 days and its effectiveness was measured by a spectrophotometer utilizing the CIE L*a*b* system (ΔE, ΔL*, Δa* and Δb*). Colour readings were measured at baseline (T0), 7 days of bleaching (T7), 14 days of bleaching (T14) and 7 days after the end of bleaching (T21). Data were analysed by two-way ANOVA for paired averages followed by the Tukey's test and Pearson's correlation at 5%. RESULTS: Although CP produced the greatest colour change (ΔE), all whitening protocols were considered to be effective regardless of the CPP-ACP presence. In general, greater changes in ΔE, ΔL*, Δa* and Δb* were detected at T14, with T21 exhibiting similar results to those at T7. A greater number of strong correlations with ΔE values was found for a* (11/15). CONCLUSIONS: Within the limitations of this study, the results indicate that the CPP-ACP paste did not affect tooth whitening efficacy.

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.