Universal Adhesive for Fixed Retainer Bonding: In Vitro Evaluation and Randomized Clinical Trial

This study aims to assess the efficacy of a universal adhesive (Scotchbond Universal, 3M ESPE) (SB) in total-etch mode, compared to a traditional orthodontic primer (Transbond XT Primer, 3M ESPE) (XT Primer), to perform bonding of orthodontic fixed retainers along with the Transbond XT Light Cure Adhesive Paste (3M ESPE). For the in vitro study, a round section wire (Ortosmail Krugg) was bonded using XT Primer for 20 bovine incisors (Group 1) and SB for other 20 (Group 2). Samples were debonded in a universal testing machine applying a tangential force to specimens (crosshead speed of 1 millimeter per minute). Shear bond strength (SBS) and adhesive remnant index (ARI) scores were calculated. For the in vivo study, 100 patients needing upper and lower canine-to-canine fixed retainers after orthodontic treatment were randomly assigned to two groups of 50 participants each, i.e., group 1 (retainer bonding with XT Primer) and group 2 (retainer bonding with SB). Over two years, examinations were carried out monthly, and detachments were registered by considering the teeth and arches affected. In vitro, no statistically significant differences in SBS and ARI scores were demonstrated between the two groups, both showing a mean bond strength of about 12 MPa and major frequency of ARI “2” (>50% remnant adhesive on the enamel). Conversely, a significantly lower failure rate over 2 years was assessed clinically for group 2 in both arches. Independently of the adhesive and arch, incisors reported a significantly higher failure rate than canines. Scotchbond Universal used in total-etch mode could be a valid alternative to the traditional orthodontic Transbond XT Primer.     

Protective effect of ellagic acid on healing alveolar bone after tooth extraction in rat—A histological and immunohistochemical study

Objective

This study has attempted to evaluate the effects of ellagic acid (EA) on alveolar bone healing after tooth extraction in rats.

Design

Twenty-four Sprague Dawley (SD) male rats (200–250 g) were selected and were anaesthetised for the extraction of upper left incisor. Then, the rats were divided into two groups, comprising 12 rats each; the first group has been considered as a control group and was given only normal saline, whereas, the second group (treated group) was intragastrically administrated with EA daily once, for 28 days. Then three rats from each group had been selected on 7th, 14th, 21st, and 28th days to dissect their maxilla tissue either for histological observation and homogenisation purposes. The tissues fixed, decalcified and embedded in paraffin. Serial sections of 5 μm thickness were prepared and stained with haematoxylin and eosin (H&E) for the histological study. Similar sections were taken for immunohistochemical analysis to assess osteocalcin (OSC) and osteopontin (OPN). Furthermore, Malondialdehyde (MDA) and superoxide dismutase (SOD) were measured in homogenated gingival maxilla tissue of rat by commercial kit.

Results

Based on the histological analysis we have identified that, EA treatment has induced earlier trabecular bone deposition in the treated group, resulting in more organised bone matrix on the 14th, 21st, and 28th days after tooth extraction, as against the control group. In comparison to control group, the positive labelling of OSC and OPN of the treated group have been highly expressed in the alveolar socket on 14th, and 21st days, which has indicated a the possibility of formation of new bone trabeculae at the beginning of the mineralisation process, after tooth extraction. In the EA treatment group, lipid per-oxidation (MDA) was significantly decreased (P < 0.05), as opposed to the control group. However, the antioxidant defense enzyme (SOD) was significantly increased in the maxilla tissue treated with EA (P < 0.05), compared to control group, which suggests that, after tooth extraction, EA plays an important role in the protection against the induction of lipid per-oxidation, particularly after 28 days of treatment with EA.

Conclusion

This study has concluded that, EA may accelerated the healing process in teeth socket of rats. Furthermore, the EA treated group showed a stronger positive immunolabelling for OSC and OPN, when compared with the control group.     

Inhibition of epidermal growth factor receptor-mediated signaling by "Combi-triazene" BJ2000, a new probe for Combi-Targeting postulates

The Combi-Targeting concept postulates that a molecule termed combi-molecule (C-molecule) with binary epidermal growth factor receptor (EGFR) targeting/DNA-damaging properties and with the ability to be hydrolyzed to another EGFR inhibitor should induce sustained antiproliferative activity in cells overexpressing EGFR. Because we postulate that the EGFR affinity of the C-molecule and that of its hydrolytic metabolites are critical parameters for sustained potency against EGFR-overexpressing cells, we synthesized BJ2000 (IC(50) = 0.1 microM, competitive binding at ATP site), a novel C-molecule that can decompose into a 6-amino-4-anilinoquinazoline FD105 (IC(50) = 0.2 microM). Studies using the EGFR-overexpressing A431 cells revealed that BJ2000 could damage DNA and block epidermal growth factor-stimulated EGFR autophosphorylation by a partially irreversible mechanism. Blockade of EGFR autophosphorylation subsequently induced inhibition of mitogen-activated protein kinase activation and c-fos gene expression. Enzyme-linked immunosorbent assay and growth factor-mediated stimulation of proliferation assays in the EGFR-expressing NIH3T3HER14 demonstrated the preferential EGFR-targeting properties of BJ2000, and more importantly suggest that blockade of EGFR phosphorylation by this drug translate into significant growth inhibitory effects. These properties culminated into irreversible antiproliferative effects as confirmed by a sulforhodamine B assay. Five days after a 2-h treatment, BJ2000 retained significant antiproliferative effect in A431 cells, whereas its reversible metabolite FD105 almost completely lost its activity. This result in toto lend support to the Combi-Targeting concept according to which a molecular conjugate kept small enough to interact with EGFR and designed to degrade into another inhibitor of the same target plus a DNA-damaging species may induce sustained growth inhibitory effect in EGFR-overexpressing cells.     

Glutathione and its metabolizing enzymes in patients with different benign and malignant diseases

Objectives: Evaluation of glutathione (GSH) system in different tumors to reveal its potential usefulness in a clinical setting.

Design and methods: In addition to 10 normal controls, blood and tissue samples (85 benign and 109 malignant) from patients with breast, ovarian, prostatic, and liver neoplasms were investigated. The GSH concentration, glutathione S-transferase, glutathione peroxidase, and glutathione reductase activities were biochemically measured.

Results: Whereas all the components of the GSH system increased in patients with breast tumors, few components were significantly changed in patients with malignant ovarian, prostatic as well as metastatic liver diseases. GSH had the highest Z scores in ovarian and breast tumors. It was correlated (p < 0.05) with both glutathione S-transferase, glutathione peroxidase in breast cancer and with glutathione S-transferase only in prostate cancer. No correlation could be found in the expression of the GSH system in the blood and tissues of the same group of patients.

Conclusion: This work revealed that measurement of some and/or all components of the GSH system might be of clinical value in some malignant cases.