Effects of post surface conditioning before silanization on bond strength between fiber post and resin cement

PURPOSE. Post surface conditioning is necessary to expose the glass fibers to enable bonding between fiber post and resin cement. The purpose of the present study was to evaluate the effect of different surface conditioning on tensile bond strength (TBS) of a glass fiber reinforced post to resin cement. MATERIALS AND METHODS. In this in vitro study, 40 extracted single canal central incisors were endodontically treated and post spaces were prepared. The teeth were divided into four groups according to the methods of post surface treatment (n=10): 1) Silanization after etching with 20% H2 O2 , 2) Silanization after airborne-particle abrasion, 3) Silanization, and 4) No conditioning (Control). Adhesive resin cement (Panavia F 2.0) was used for cementation of the fiber posts to the root canal dentin. Three slices of 3 mm thick were obtained from each root. A universal testing machine was used with a cross-head speed of 1 mm/minute for performing the push-out tests. Two-way ANOVA and Tukey post hoc tests were used for analyzing data (α=0.05). RESULTS. It is revealed that different surface treatments and root dentin regions had significant effects on TBS, but the interaction between surface treatments and root canal regions had no significant effect on TBS. There was significant difference among H2 O2 + Silane Group and other three groups. CONCLUSION. There were significant differences among the mean TBS values of different surface treatments. Application of hydrogen peroxide before silanization increased the bond strength between resin cements and fiber posts. The mean TBS mean values was significantly greater in the coronal region of root canal than the middle and apical thirds. [J Adv Prosthodont 2013;5:126-32

In Vitro Study of Transverse Strength of Fiber Reinforced Composites

Objective: Reinforcement with fiber is an effective method for considerable improvement in flexural properties of indirect composite resin restorations. The aim of this in-vitrostudy was to compare the transverse strength of composite resin bars reinforced with preimpregnated and non-impregnated fibers.Materials and Methods: Thirty six bar type composite resin specimens (3×2×25 mm)were constructed in three groups. The first group was the control group (C) without any fiber reinforcement. The specimens in the second group (P) were reinforced with preimpregnatedfibers and the third group (N) with non-impregnated fibers. These specimens were tested by the three-point bending method to measure primary transverse strength.Data were statistically analyzed with one way ANOVA and Tukey's tests.Results: There was a significant difference among the mean primary transverse strength in the three groups (P<0.001). The post-hoc (Tukey) test showed that there was a significant difference between the pre-impregnated and control groups in their primary transversestrength (P<0.001). Regarding deflection, there was also a significant difference among the three groups (P=0.001). There were significant differences among the mean deflection of the control group and two other groups (PC&N<.001 and PC&P=.004), but there was no significant difference between the non- and pre-impregnated groups (PN&P=.813).Conclusion: Within the limitations of this study, it was concluded that reinforcement with fiber considerably increased the transverse strength of composite resin specimens, but impregnationof the fiber used implemented no significant difference in the transverse strength of composite resin samples

Modulation of Macrophage Function by Lactobacillus-Conditioned Medium

open access articleProbiotics are used as microbial food supplements for health and well-being. They are thought to have immunomodulatory effects although their exact physiological mechanism of action is not clear. This study investigated the influence of probiotic Lactobacillus rhamnosus GG conditioned media (LGG-CM) on macrophage phagocytosis of non-pathogenic Escherichia coli HfrC. The gentamicin protection assay was used to study the bacterial killing phases of phagocytosis. Macrophages co-incubated with E. coli for an hour allowed them to ingest bacteria and then the rate of E. coli killing was monitored for up to 300 min to determine the killing or digestion of the bacteria by recovering them from the macrophage lysate. We found that the LGG-CM significantly increased the bacterial killing by approximately 6-fold when compared with that of controls. By contrast, this killing process was found to be associated with enhanced free radical production via the activation of NADPH oxidase, stimulated by the LGG conditioned medium. We also found that the conditioned medium had small effect on nitric oxide (NO) generation, albeit to a lesser extent. This work suggests that LGG-CM may play an important role in suppressing the total microbial load within the macrophages and hence, the extent to which pro-inflammatory molecules such as free radicals and NO are generated. The modulation of inflammation-promoting signals by LGG-CM may be beneficial as it modulates bacterial killing, and thereby prevents any collateral damage to host

Estimation of (co)variance components and breeding values for test-day milk production traits of Holstein dairy cattle via Bayesian approach

Genetic parameters of milk, fat, and protein yields were estimated in the first lactation of Holstein dairy cattle. The records were collected during the period 2006 to 2011 and analyzed fitting the random regression model. The data included 41178, 25397 and 18716 test-day records of milk, fat and protein yields, respectively that produced by 4746, 3437 and 2525 cows respectively. Fixed effects in model included herd-year-month of test day and age-season of calving. The fixed and random regressions were modeled with normalized Legendre polynomials and (co)variance components were estimated by Bayesian method and Gibbs sampling was used to obtain posterior distributions. Estimates of heritability for milk, fat and protein yields ranged from 0.18 to 0.26; 0.06 to 0.11 and 0.09 to 0.22, respectively. Heritabilities for 305-d milk, fat and protein yields were 0.36, 0.23 and 0.29, respectively. For milk and protein yields, heritabilities were lower at the early of lactation due to the trends of lower additive genetic variance, higher permanent environmental variance. Genetic correlations for milk, fat and protein yields ranged from 0.14 to 1.00; 0.39 to 1.00 and 0.27 to 1.00, respectively. Ranges of estimated breeding values for 305-d yield of milk, fat and protein yields were from -1194.48 to 1412.44; -210.57 to 271.22 and -194.08 to 203.25, respectively. According to the results of this study, random regression model seems to be a flexible and reliable procedure for the genetic evaluation of milk production traits and it can be useful in the breeding programs for Iranian dairy cattle

Amorphous formulations of indomethacin and griseofulvin prepared by electrospinning

Following an array of optimization experiments, two series of electrospun polyvinylpyrrolidone (PVP) fibers were prepared. One set of fibers contained various loadings of indomethacin, known to form stable glasses, and the other griseofulvin (a poor glass former). Drug loadings of up to 33% w/w were achieved. Electron microscopy data showed the fibers largely to comprise smooth and uniform cylinders, with evidence for solvent droplets in some samples. In all cases, the drug was found to exist in the amorphous physical state in the fibers on the basis of X-ray diffraction and differential scanning calorimetry (DSC) measurements. Modulated temperature DSC showed that the relationship between a formulation’s glass transition temperature (<i>T</i>_g) and the drug loading follows the Gordon–Taylor equation, but not the Fox equation. The results of Gordon–Taylor analysis indicated that the drug/polymer interactions were stronger with indomethacin. The interactions between drug and polymer were explored in more detail using molecular modeling simulations and again found to be stronger with indomethacin; the presence of significant intermolecular forces was further confirmed using IR spectroscopy. The amorphous form of both drugs was found to be stable after storage of the fibers for 8 months in a desiccator (relative humidity <25%). Finally, the functional performance of the fibers was studied; in all cases, the drug-loaded fibers released their drug cargo very rapidly, offering accelerated dissolution over the pure drug

REMAINED DENTAL PARTICLES IN THE JAWS OF EDENTULOUSPATIENTS (ISFAHAN. 1999)

Remained teeth and other lesions such as cysts, abcesses and tumors is one of the important problems in edentulous patients.&#13; In a cross-sectional study, 330 edentulous patients were evaluated radiographically. The radiographic evaluation of patients revealed the presence of 86 residual roots in 58 radiographs. 17.58% of patients had residual roots &amp; 5.8% of patients had Impacted teeth. 58.1% of residual roots and 45% of impacted teeth were in the maxilla and others were in mandible. Maximum Percentage of residual roots (58.1%) and impacted teeth (70%) were found in molar region. In this study revealed 23.3% of examined patients had remaining dental fragments. From these patients, 5.76% had impacted teeth and 17.58% had residual roots, and maximum percentage of rooth fragments (58.1%) were found in molar region. In similar study by spyropoulus, maximum percentage of root fragments (45.6%) reported in molar region and maximum percentage of impacted teeth were found in molar and canine region (41.2% in molar and 41.2 in canine region). In this study, 58.1% of root fragments and 45% of impacted teeth were found in the maxilla but in spyropoulos" report, 71.9% of root fragments and 94.1% of impacted teeth were found in the maxilla

An investigation on the facial midline distance to some anatomic landmarks of the jaws among people with natural dentition

The determination of the dental midline is necessary in most dental procedures.&quot;nOne of the methods to fulfill this goal is to determine the facial midline based on the midpoints of the&quot;nforehead, nose, upper lip and chin. However, for various reasons, this method has not always been&quot;nproved successful. In such cases, different techniques, based on the investigations in the edentulous&quot;npatients, have been suggested.&quot;nPurpose: The aim of this study was to investigate the conformity of some landmarks such as labial&quot;nfrenum, incisive papilla and mid palatal suture with dental and facial midlines among people with natural&quot;ndentition in order to obtain accurate anatomic landmarks for denture replacement.&quot;nMaterials and Methods: In this descriptive study, 96 dental students, having all their permanent teeth&quot;nand without any orthognathic problem, were chosen. For each subject, Alginate impressions and dental&quot;ncasts were prepared. Then, centric occlusion was recorded with a biting wax and the facial mid line was&quot;ndetermined on the anterior part of it. The distances from the facial midline to the upper teeth midline,&quot;nincisive papilla, labial frenum and mid palatal suture were determined with a special tool and were&quot;nmeasured by a VERNIEH two times. In order to analyze the results, Chi- Square and t-student tests were&quot;nused.&quot;nResults: The average of facial midline distance to the upper teeth midline, the labial frenum, the incisive&quot;npapilla and the mid palatal suture were 0.83&amp;plusmn;0.60, 0.67&amp;plusmn;G.54, 0.83&amp;plusmn;00.63 and 0.81&amp;plusmn;0.62 mm,&quot;nrespectively. There was no significant difference between males and females. Labial frenum showed the&quot;nminimum distance to the facial midline, while the incisive papilla had the maximum. There was no&quot;nsignificant difference between these anatomic landmarks, in conformity or unconformity with the facial&quot;nmidline&quot;nConclusion: Considering the low percentage of the subjects with complete conformity and the lack of&quot;nsignificant differences between these three landmarks, it is suggested that there is no superiority among&quot;nthese landmarks for the determination of facial midline. The similar distances from the facial midline to&quot;nthe incisive papilla and upper teeth midline indicate that using incisive papilla to determine the upper&quot;nteeth midline in edentulous patients lead to normal face