Cerium oxide nanoparticle elicits oxidative stress, endocrine imbalance and lowers sperm characteristics in testes of balb/c mice.

The toxicity of metallic nanoparticles is a growing concern due to its application in industries and homes. We investigated the toxicity of cerium oxide nanoparticles (CeO2 NPs) on reproductive system in male balb/c mice. Twenty mice were divided into four groups of five animals each and treated thus: normal saline (control), 100, 200 and 300 µg/kg CeO2 NPs (i.p.,) thrice in a week for five consecutive weeks. Results showed that CeO2 NPs significantly reduced the levels of haemoglobin, PCV and RBC count relative to controls. In addition, luteinising and follicle-stimulating hormones (FSH and LH) and prolactin were significantly reduced in the mice. Specifically, CeO2 NPs at 100 µg/kg decreased testosterone by 23%, while CeO2 NPs at 200 µg/kg decreased FSH, LH and prolactin by 25%, 26% and 13%, respectively. Testicular malondialdehyde was increased by 103%, 106% and 135% in mice treated with 100, 200 and 300 µg/kg CeO2 NPs, respectively. CeO2 NPs caused a significant reduction in activities of antioxidant enzymes and levels of reduced glutathione and total nitric oxide. Moreso, CeO2 NPs decreased sperm motility and count and increased total sperm abnormality in mice. Histology revealed congestion and degeneration of seminiferous tubules. Overall, CeO2 NPs induces testicular dysfunction via disruption of antioxidant/oxidant balance and endocrine suppression.

The coagulating gland in the male greater cane rat (Thryonomys swinderianus): morphological and immunohistochemical features.

This study reveals the structure, ultrastructure and immunoexpression of oestrogen alpha and beta receptors (ERα and ERß) in the coagulating glands of the greater cane rat. Gland samples from 15 adult male cane rats were processed for histological and ultrastructural studies while immunohistochemistry was also carried out. Coagulating gland in the cane rat is a paired, triangularly shaped, transparent gland weighing about 1 ± 0.48 g. Histologically, each secretory acinus is composed of folded mucosa surrounded by fibromuscular stroma. The simple columnar epithelium consists of principal cells at different stages of secretion evidenced by their apical blebs of various heights and occasional basal cells. Fine structure of the principal cells revealed the presence of apical blebs that contained secretory granules of varying electron-density, secretory vesicles and vacuoles on both their luminal surfaces and the lumen. While supranuclear cytoplasm contained Golgi apparatus with different cisternal arrangements, the infranuclear part is covered with dilated rough endoplasmic reticulum cisternae. Nuclei, apical bleb and stroma of secretory epithelium all showed positive immunostaining for ERα and ERß. These findings revealed the prominence of apocrine secretion with no structural evidence of merocrine secretion and the uncommon ERα and ERß distribution pattern in the coagulating gland of the cane rat.

Effect of tooth surface preparation on the bonding of self-etching primer adhesives.

The aim of this study was to determine the bonding effectiveness of four self-etching primer adhesives after various tooth preparation protocols. Enamel/dentin specimens were prepared from 84 permanent molars, divided into three enamel preparation groups (silicon carbide paper [SiC1; erbium, chromium:yttri-um, scandium, gallium, garnet [Er,Cr:YSGG] laser [EL] and diamond bur [DB]) and five dentin preparation groups (SiC, EL, DB, steel[SB], and ceramic burs [CBs]). In each group,specimens were equally divided into four sub-groups and were bonded using Clearfil SEBond (CSE, Kuraray), Xeno IV (XE, Dentsply),Tokuyama Bond Force (TK, Tokuyama) and Filtek Silorane System Adhesive (FS, 3MESPE), as well as a hybrid resin composite(Clearfil Majesty Esthetic, Kuraray) for CSE,XE, and TK, and Filtek Posterior Restorative(3M ESPE) for FS). After 24 hours of water storage at 370C, microshear bond strength(iSBS) testing was carried out. Data were analyzed using analysis of variance (ANOVA)-Tukey test at a=0.05 and bond failure modes assessed. Representative debonded specimens were prepared and examined under the scanning electron microscope (SEM). All adhesives exhibited no significant differences in 1SBS on enamel and dentin under the clinical cavity preparation protocols, except for TK on den-tin. SEM revealed areas of altered subsurface enamel/dentin following EL ablation.

Dentine bonding after CPP-ACP paste treatment with and without conditioning.

OBJECTIVES: To evaluate microshear bond strength (MSBS) to dentine following application of a casein phosphopeptide amorphous calcium phosphate paste (Tooth Mousse (TM)), and the effect of smear layer removal before paste application and preconditioning. METHODS: Specimens of polished human dentine were divided into two groups: 1, smear layer retained; 2, smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were left untreated and half treated with TM for 60 min daily x 7 days. Each subgroup was divided into three further subgroups for conditioning (Primer only; 30-40% phosphoric acid (PA)+primer; 20% polyacrylic acid (CC)+primer). Two self-etching/priming adhesives (Clearfil SE Bond (CSE) and G-Bond (GB)) were used for bonding resin composite to superficial/deep dentine and after 24h, stressed in shear until failure. Maximum loads at failure and bond failure modes were recorded. Group means were compared using one-way ANOVA and Tukey's post hoc test at alpha=0.05. RESULTS: TM did not significantly affect MSBS in group 1. In group 2, there was a statistically significant increase in MSBS for CSE on deep dentine (P=0.002) and a reduction for GB (P=0.013) on superficial dentine. PA conditioning did not significantly affect MSBS for CSE and GB while CC significantly reduced MSBS for GB. CONCLUSIONS: TM application did not reduce MSBS for CSE but significantly reduced MSBS for GB when the smear layer was removed before paste treatment. Preconditioning did not improve or worsen dentine MSBS for CSE or GB with/without TM, except when CC was used with GB.

Bond strength test: role of operator skill.

BACKGROUND: Test method, substrate material and operator variability are factors known to affect bond strength test outcomes. The aim of this study was to determine if, with increasing experience, individual operator skill in material handling influenced microshear bond strength outcomes. METHODS: This retrospective study used data collected from six preliminary tests carried out successively on enamel microshear bond strength for two adhesives: Clearfil SE Bond (Kuraray) and Adper Single Bond 2 (3M ESPE) by one operator. Mean and median microshear bond strength values, standard deviations and coefficients of variation for each adhesive test group were calculated and assessed. RESULTS: A gradual increase in mean microshear bond strengths, a decrease in standard deviations and coefficients of variation over time for both adhesives and a progressively more uniform distribution of microshear bond strength results recorded in individual test sets was observed. The results suggest an improvement in bonding reliability as experience is gained. CONCLUSIONS: Operator skill in material handling appears to play a critical role in determining the outcome of bond strength testing. This same skill is probably relevant when using an adhesive for the first time clinically. It is important that clinicians become familiar with new adhesives in order to achieve optimal outcomes.

Effects of conditioners on microshear bond strength to enamel after carbamide peroxide bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment.

OBJECTIVES: To evaluate (a) the enamel microshear bond strength (MSBS) of a universal adhesive and (b) the effects of conditioning with a self-etching primer adhesive with/without prior bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application. METHODS: Thirty-five molars were cut into four sections, assigned randomly to four groups (no treatment; 16% carbamide peroxide bleaching; CPP-ACP-containing paste (Tooth Mousse, TM); bleaching and TM) and treated accordingly. Specimens were divided into two for bonding with either a self-etching primer (Clearfil SE Bond, CSE) or a total-etch adhesive (Single Bond, SB). Specimens for CSE bonding were subdivided for one of four preconditioning treatments (no conditioning; 30-40% phosphoric acid (PA); 15% EDTA; 20% polyacrylic acid conditioner (Cavity conditioner, CC) and treated. The adhesives were applied and resin composite bonded to the enamel using microtubes (internal diameter 0.75mm). Bonds were stressed in shear until failure, mean MSBS calculated and data analysed using ANOVA with Tukey's HSD test (alpha=0.05). The modes of bond failure were assessed and classified. RESULTS: Two-way ANOVA revealed significant differences between treatments (P<0.0001), conditioners (P<0.0001) and a significant interaction between treatments and conditioners (P=0.001). One-way ANOVA revealed no significant differences in MSBS following any of the treatments for SB; following TM application for CSE without preconditioning; and significant differences in MSBS following bleaching with and without TM application for CSE. With preconditioning, applying PA before CSE post-bleaching and either PA or CC before CSE post-TM application, resulted in significant differences in MSBS (P<0.05). CONCLUSIONS: The use of conditioners prior to bonding with the self-etching primer adhesive system on treated enamel may significantly improve bond strengths.

Relationship between composite fracture toughness and bond strengths to enamel and dentine.

BACKGROUND: This study aimed to evaluate the association between the fracture toughness of two nanofilled-hybrid resin composites (Clearfil Majesty Esthetic [CME], Kuraray Medical, Japan; Estelite Σ [ES], Tokuyama, Japan) and their bond strengths to enamel and dentine mediated by a self-etching primer system (Clearfil SE Bond [CSE]; Kuraray). METHODS: Twenty-four permanent human molars were sectioned into enamel and dentine specimens and finished with 600-grit silicon carbide paper, bonded with CSE and either CME or ES, for µ-shear bond strength (µSBS) and µ-tensile bond strength (µTBS). The specimens were tested until failure at a cross-head speed of 1 mm/min, failure loads recorded, bond strengths calculated and results analysed using independent samples t-tests. Eight single-notched bar-shaped specimens, 30 mm × 5.2 mm × 2.2 mm, were prepared for each resin composite and fracture toughness measured using four-point bending at a cross-head speed of 0.5 mm/min. Results were analysed using independent samples t-tests. RESULTS: For µSBS and µTBS, there was no significant difference between the resin composites for enamel or dentine. The fracture toughness of CME was significantly higher than that of ES. CONCLUSIONS: For both enamel and dentine, resin composite fracture toughness affected neither µTBS nor µSBS to enamel or dentine.

Resin-dentine interfacial morphology following CPP-ACP treatment.

OBJECTIVES: To evaluate the quality of bonded resin-dentine interfaces produced by two self-etching primer adhesives after casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment, in comparison to untreated dentine. METHODS: Thirty-four adult molar teeth were sectioned to obtain dentine with tubule orientations parallel/oblique or perpendicular to the surface. The specimens were divided into 'smear layer' (1A, 1B) and 'no smear layer' groups, after treatment with 15% EDTA (2A, 2B). The specimens were then left either untreated (1A, 2A) or treated (1B, 2B) with CPP-ACP paste (Tooth Mousse, GC Corp.) for 60 min x 7 days. Each treatment group was divided into three subgroups and specimens etched/conditioned (no conditioning; 30-40% phosphoric acid (H(3)PO(4)); 20% polyacrylic acid) and bonded with either a 2-step self-etching primer adhesive (Clearfil SE Bond, Kuraray Medical) or an 'all-in-one' adhesive (G-Bond, GC Corp.) and a hybrid resin composite. After 24-h water storage, the bonded specimens were sectioned, polished up to 4000-grit abrasive silicon carbide paper and 0.25-microm diamond paste, prepared for FE-SEM using the acid-base technique, critical point-dried, gold-coated and examined. Bonded and fractured dentine interfaces were also prepared and examined. RESULTS: The 2-step adhesive produced a similar appearance of bonded resin-dentine interface irrespective of smear layer group, treatment or etching/conditioning. After polyacrylic acid conditioning, the 'all-in-one' adhesive exhibited more areas with bond failures. The bond failures were within the hybrid layer and more pronounced following CPP-ACP treatment. CONCLUSION: The quality of the bonded resin-dentine interface produced after CPP-ACP treatment may depend on the adhesive system used.

An SEM evaluation of conditioned and bonded enamel following carbamide peroxide bleaching and casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment.

OBJECTIVES: The study aimed to evaluate, (a) the surface morphology of acid etched/conditioned enamel following carbamide peroxide bleaching with/without casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) (Tooth Mousse (MI Paste); GC Corp., Tokyo, Japan) treatment; and b) the nature of the bonded resin-enamel interfaces formed with a self-etching primer adhesive. METHODS: Twenty-four human adult molars were each sectioned into four, the specimens divided and treated according to four experimental groups: 1, no treatment; 2, 16% carbamide peroxide bleaching; 3, CPP-ACP paste; 4, bleaching and CPP-ACP paste. A self-etching primer adhesive (Clearfil SE Bond, CSE) was used. The specimens were further divided into four subgroups for etching/conditioning: A, CSE Primer only; B, 30-40% phosphoric acid and CSE primer; C, 15% EDTA and CSE primer; D, 20% polyacrylic acid and CSE primer. Bonded specimens were also prepared. The morphology of the etched/conditioned enamel surfaces and polished resin-enamel interfaces of the bonded specimens were observed by field-emission scanning electron microscopy (FE-SEM). RESULTS: Treatment with CPP-ACP did not inhibit phosphoric acid etching of enamel. Poorly defined enamel etch patterns were observed with the other conditioners in all the groups. The morphology of the bonded resin-enamel interfaces observed on FE-SEM for each acid etching/conditioning subgroup was similar in all the experimental groups, except after bleaching. Resin infiltration into enamel was observed with prior phosphoric acid etching and polyacrylic acid conditioning and was unaffected by experimental group treatments. CONCLUSIONS: The use of a CPP-ACP paste with or without prior bleaching did not inhibit enamel etching. Enamel etching/conditioning may help improve bonding efficiency of the self-etching primer adhesive after CPP-ACP treatment.