Journal of Dental Materials and Techniques
Volume:9 Issue: 1, Winter 2020

Microorganisms are very important in the initiation of pulpo-periapical pathosis. Due to the complexity of the root canal system, the mechanical instrumentation of the root canal system should be supplemented with proper canal irrigants and medicaments. It has been revealed that due to the interactions of canal irrigants and medicaments with dentin and contents of the canal system, the antimicrobial effect of canal irrigants and medicaments in canal (ex vivo) are different from that in vitro. Furthermore, root canal irrigants may decrease the fracture resistance of dentin. The purpose of this paper was to review the data on the interactions between root canal irrigants/medicaments and dentin/root canal contents.

The aim of this in vitro study was to evaluate imaging artifacts induced by Titanium, Zirconium, Titanium-Zirconium abutments in CT, MRI and CBCT imaging modalities. A 4×8mm titanium fixture was inserted in a dry human mandible. Titanium, Zirconium and Titanium–Zirconium abutments measuring 10.5 mm in height are located on the fixture, one by one. Each abutment was scanned 4 times by each imaging modality. Gray value of the images was evaluated in four determined regions adjacent to distal, mesial, buccal and lingual aspects of the implant as the region of interest (ROI) by two observers using image J software. Gray value differences (∆GV) between the control (fixture without abutment) and case images (fixture and each type of abutments) were calculated. Data evaluation was done by analysis of variance and Post Hoc tests. In CBCT, ∆GV was significantly higher in zirconium-titanium images comparing with titanium abutments. (P Value < 0.05)In distal, mesial and buccal aspects of ROI in CT, ∆GV was higher in zirconium images comparing with titanium abutments.In MRI, ∆GV for zirconium were lower than titanium-zirconium and titanium samples, respectively. Also, no significant differences in ∆GV were seen between T1 and T2 protocols, for all samples. In MRI, image artifacts are the least around Zirconium abutments, while in CT and CBCT, titanium abutments produced the least amount of artifacts.

Effect of zinc oxide-eugenol (ZO-E) on bond strength of composite is equivocal. The aim of the present study was to determine if ZO-E affects shear bond strength. For the purposes of the study, extracted human molar teeth were ground so thatcomposite rods could be bonded to dentine. In group 1, dentine was not exposed to ZO-E. In group 2, ZO-E was applied to dentine for 10 days prior to acid etching and bonding the composite. A universal testing machine was used to determine the composite’s shear bond strength. Data were analyzed using t-test. Mean score of shear bond strengths were 137.15 (± 46.82) and 140.08 (± 40.39) N for groups 1 and 2, respectively, with no statistically significant difference. Majority of samples in Group 1 (74% vs. 65%) had “clean breaks” where the composite fractured without any dentine attached, while the rest of the samples had some dentine attached. ZO-E can be used for temporary fillings without affecting bond strength of subsequent composite restorations.

Iron supplementation in children under 5 years of age is recommended on the basis of anaemia prevention. This study aims to assess the mother’s knowledge and practice towards the effects of iron supplementation on dental caries and staining in children aged 6 months to 2 years in Yazd, Iran. A randomized cross-sectional study was conducted on 403 mothers of children (aged 6 months to 2 years) who referred to healthcare centers in Yazd during 2011. The mothers' knowledge and practice levels were assessed using a questionnaire, and the results were categorized into sufficient or insufficient. The Chi-square test was used to analyze the data. According to the results, 241 (59.8%), and 273 (67.7%) mothers obtained sufficient levels of knowledge, and practice, respectively. Moreover, mothers’ educational levels had a statistically significant relationship with their knowledge regarding iron supplementation (P<0.001). Additionally, the mother’s practice toward iron supplementation correlated significantly with mothers’ educational level (P<0.001) and occupational status (P=0.018), as well as the birth order of the child (P<0.001). More than half of the mothers had sufficient knowledge and practice towards the effects of iron supplementation on dental caries and staining

Silver nanoparticles (SNPs) have recently been suggested to increase the antimicrobial properties of soft liner materials. However, their safety remains a matter of debate. This study aimed to evaluate the cytotoxicity of Mucopren® soft silicone liner material (Mucopren; Kettenbach, Germany) incorporated in SNPs. The SNPs with over 98% purity were added to Mucopren in 0.5, 1, 2, and 3 weight percentage (wt%) concentrations and manually homogenized. The mixture of the pieces of Mucopren plus SNPs and SNPs alone were placed in 96-well plates containing Dulbecco's Modified Eagle Medium culture, FBS, and antibiotics with L929 fibroblasts. Cell viability and biocompatibility were determined after 1, 2, and 3 days of incubation using the methylthiazol tetrazolium assay. Optical density was read by an ELISA reader at 570 nm and compared to those of positive and negative controls. Among Mucopren mixed with different SNPs concentration, the cell toxicity had no significant difference in the same days, and cell toxicity decreased over time (P=0.016). The SNPs alone were less cytotoxic than Mucopren incorporated SNP samples (P>0.05). Within the limitations of this study, the addition of 0.5, 1, 2, and 3wt% concentrations of SNPs to Mucopren did not cause a significant change in its cell toxicity in an in vitro condition

An accurate impression is essential to create a well-fitted dental prosthesis. This study aimed to compare the dimensional accuracy of three elastomeric materials using one-step and two-step impression techniques. In this study, 20 impressions were fabricated for each Vinyl siloxane ether (Identium), condensation silicone (Speedex), and additional silicone (Panasil) impression materials by the one-step and two-step impression techniques using perforated metal trays. The one-step impression technique was simultaneously performed with heavy body/light-body materials. In the two-step impression technique, acrylic copings with 2-mm thickness were placed on the abutments to obtain similar spacing for the light-body material. The dimensional accuracy of different impression materials and techniques were measured using distance differences of the stone dies from the master cast; subsequently, the results were compared with the reference model. Data were analyzed using a one-way analysis of variance and Dunnett’s tests (α=0.05). All impression materials demonstrated an acceptable clinical accuracy. Identium (Vinyl siloxane ether) displayed the most accuracy in both the one-step and two-step impression techniques (P>0.05). The best accuracy for Panasil (additional silicone) was found to be the two-step impression technique (P>0.05), and the best accuracy for Speedex (condensation silicone) was reported as the one-step impression technique (P>0.05). Furthermore, the one-step impression technique was highly accurate in diameter dimension, as compared to the two-step impression technique. As evidenced by the results, the accuracy of impression is affected by the impression materials. Moreover, Identium (Vinyl siloxane ether) demonstrated the most accuracy in both one-step and two-step impression techniques.

This study aimed to investigate the impact of N-vinylcaprolactam (NVC) and Nano-sized yttria-stabilized zirconia (YSZ), separately and simultaneously, on the mechanical properties of the commercial glass ionomer cements (GICs). The NVC is able to ameliorate the mechanical and surface properties of glass ionomers; however, its effect hasn’t been investigated in conjunction with zirconia yet. In order to perform the current research, the liquid of glass ionomer was synthesized by adding the NVC to its copolymer and then was characterized by proton nuclear magnetic resonance and Fourier transforms infrared. In addition, Nano-sized YSZ was added to the powder of glass ionomer and then was characterized by scanning electron microscopy. Afterward, the specimens for both flexural strength (FS) and microhardness were prepared by mixing the powder and liquid of the modified glass ionomer. Eventually, the aforementioned properties were evaluated after 24 h and 1 week of immersion in distilled water in an incubator. Furthermore, the one-way analysis of variance was used to study the statistical significance of FS. The obtained results demonstrated that microhardness andFS properties of the glass ionomer were clearly improved as zirconia and NVC were added to the powder and liquid of the glass ionomer, respectively (P<0.05). Moreover, the best result was achieved for the group in which the modification of powder and liquid of glass ionomer occurred concurrently. Based on the findings of the present study, it was deduced that the modified GIC is a promising dental material with improved mechanical properties.

This study aimed to devise customized fixtures for the evaluation of three-point bending strength (TPBS) of resin-based dental composites (RBCs). A cube-shaped jig made out of wood with dimensions of 105×105×101 mm was prepared in this study. A 20-mm-diameter hole was made in the center of the wooden jig. In addition, a stainless steel probe with 175mm length, 3mm thickness, and 2 mm width was fabricated and then fitted in the upper gripping crosshead of the universal testing machine. Subsequently, bar-shaped specimens of two commercial RBCs, namely Filtek Z350 XT Supreme Ultra Universal (Z350) and Premium Nano-Hybrid Composite (PN) were placed over the center of the jig hole and subjected to TPBS test in accordance with ISO 4049 standards protocol. The mean TPBS values of Z350 and PN RBCs were 82 and 86 MPa, respectively. Moreover, the standard deviation values for both mean TPBS values were low indicating the homogeneity of the findings and associated reliability of the employed fixtures. The fixtures for the TPBS test of RBCs were successfully designed and developed which would likely facilitate the researchers with a mechanical characterization of dental materials. A machine used for the testing of large industrial materials other than small dimensional dental materials can now be used to test TPBS of RBCs according to ISO 4049 with the help of the invented economical fixtures. This will enhance the quality of teaching and learning of materials science in developing countries.