Effect of tetracycline on the bond performance of etch-and-rinse adhesives to dentin

This study evaluated the effect of modified tetracycline on the resin-dentin bond strength (µTBS), silver nitrate uptake (SNU) and solution homogeneity (SH) of two adhesives. Dentin surfaces were treated with phosphoric acid, rinsed off and either rewetted with water (control group - CO), 2 percent minocycline (MI), 2 percent doxycyline (DO) or 2 percent chlorhexidine (CH). Adhesive systems (Adper Single Bond 2 and Prime Bond NT) and composite were applied and light-polymerized. Specimens were sectioned to obtain bonded sticks (0.8 mm²) to test under tension at 0.5 mm/min. For SNU, specimens were immersed in silver nitrate and analyzed by EDX-SEM. SH was qualitatively analyzed after mixing the adhesives with different solvent-based solutions containing MI, DO and CH. Lower µTBS values were observed in the DO group compared with MI and CH (p = 0.01). Lower SNU was observed for MI and CH. The lowest µTBS for both adhesives was observed for the DO group (p = 0.01). Signs of phase separation were observed for DO with both adhesives. MI or CH used as rewetting solutions after acid etching did not affect the µTBS and hybrid layer quality.

Characterization of aqueous silver nitrate solutions for leakage tests

OBJECTIVE: To determine the pH over a period of 168 h and the ionic silver content in various concentrations and post-preparation times of aqueous silver nitrate solutions. Also, the possible effects of these factors on microleakage test in adhesive/resin restorations in primary and permanent teeth were evaluated. MATERIAL AND METHODS: A digital pHmeter was used for measuring the pH of the solutions prepared with three types of water (purified, deionized or distilled) and three brands of silver nitrate salt (Merck, Synth or Cennabras) at 0, 1, 2, 24, 48, 72, 96 and 168 h after preparation, and storage in transparent or dark bottles. Ionic silver was assayed according to the post-preparation times (2, 24, 48, 72, 96, 168 h) and concentrations (1, 5, 25, 50 percent) of solutions by atomic emission spectrometry. For each sample of each condition, three readings were obtained for calculating the mean value. Class V cavities were prepared with enamel margins on primary and permanent teeth and restored with the adhesive systems OptiBond FL or OptiBond SOLO Plus SE and the composite resin Filtek Z-250. After nail polish coverage, the permanent teeth were immersed in 25 percent or 50 percent AgNO3 solution and the primary teeth in 5 percent or 50 percent AgNO3 solutions for microleakage evaluation. ANOVA and the Tukey's test were used for data analyses (α=5 percent). RESULTS: The mean pH of the solutions ranged from neutral to alkaline (7.9±2.2 to 11.8±0.9). Mean ionic silver content differed depending on the concentration of the solution (4.75±0.5 to 293±15.3 ppm). In the microleakage test, significant difference was only observed for the adhesive system factor (p=0.000). CONCLUSIONS: Under the tested experimental conditions and based on the obtained results, it may be concluded that the aqueous AgNO3 solutions: have neutral/alkaline pH and service life of up to 168 h; the level of ionic silver is proportional to the concentration of the solution; even at 5 percent concentration, the solutions were capable of indicating loss of marginal seal in the composite restorations; the 3-step conventional adhesive system had better performance regarding microleakage in enamel on primary and permanent teeth.

Changes of gastrointestinal argyrophil endocrine cells in the osteoporotic SD rats induced by ovariectomy

The regional distributions and frequencies of argyrophil endocrine cells in gastrointestinal (GI) tract of osteoporotic Sprague-Dawley rat induced by ovariectomy were studied using Grimelius silver stain. The experimental animals were divided into two groups, one is non-ovariectomized group (Sham) and the other is ovariectomized group (OVX). Samples were collected from each part of GI tract (fundus, pylorus, duodenum, jejunum, ileum, cecum, colon and rectum) at 10th week after ovariectomy or sham operation. In this study, argyrophil cells were detected throughout the entire GI tract with various frequencies regardless of ovariectomy. Most of these argyrophil cells in the mucosa of GI tract were generally spherical or spindle in shape (open type cell) while cells showing round in shape (close type cell) were found occasionally in gastric and/or intestinal gland regions. The regional distributions of GI argyrophil endocrine cells in OVX were similar to those of Sham. However, significant decreases of argyrophil cells were detected in OVX compared to those of Sham except for the pylorus, jejunum and cecum. In pylorus and jejunum, argyrophil cells in OVX dramatically decreased compared to those of Sham but significances were not recorded. In addition, argyrophil cells in cecum of OVX showed similar frequency compared to that of Sham. The endocrine cells are the anatomical units responsible for the production of gut hormones that regulate gut motility and digestion including absorption, and a change in their density would reflect the change in the capacity of producing these hormones and regulating gut motility and digestion. Ovariectomy induced severe quantitative changes of GI argyrophil endocrine cell density, and the abnormality in density of GI endocrine cells may contribute to the development of gastrointestinal symptoms in osteoporosis such as impairments of calcium and some lipids, frequently encountered in patients with postmenopausal osteoporosis.