ABSTRACT
Statement of the Problem: Endodontic irrigants and medicaments may affect the bond strength of intracanal posts to root dentin
Purpose: The aim of this study was to compare the effect of calcium hydroxide [Ca[OH][2]] and 2% chlorhexidine gel [CHX] on bond strength of fiber post cemented with resin cement to root dentin
Materials and Method: This in vitro experimental study was conducted on 36 mandibular premolars. Canals were prepared using the step back technique. After root canal irrigation, the teeth were divided into three groups of 12. Ca[OH][2] paste and CHX gel were used as intracanal medicaments in the first and second groups respectively. No intracanal medicament was used in the third group [control group]. Access cavities were then sealed and the teeth were incubated for one week. The root canals were then filled using gutta percha and AH26 sealer and the teeth were incubated for 72 hours. Tooth crowns were then cut at the level of the cementoenamel junction and intracanal posts were placed. The teeth were mounted in auto-polymerizing acrylic resin, and incubated for one week .They were then sectioned into 1.5mm thick slices from their coronal surface using a fully automated cutting machine, and subjected to push-out test until failure. The load at debonding was recorded and data were analyzed using one-way ANOVA, post-hoc test and t-test. The coronal margin of the root was at the level of the surface of acrylic resin in the mold
Results: The mean bond strength was 4.45 MPa in the Ca[OH][2], 2.45 MPa in the CHX and 2.48 MPa in the control group. The difference in this regard was statistically significant among groups [p= 0.04]. The Ca[OH][2] group had significant differences with the CHX and control groups [p= 0.03 and p= 0.02, respectively]. The difference between the CHX and control groups was not significant [p= 0.974]
Conclusion: Based on the results, Ca[OH][2] increased the bond strength of fiber post to root dentin but 2% CHX had no effect on bond strength
ABSTRACT
Shape and size of upper anterior teeth are important in dental and facial beauty. The aim of this study was to determine the correlation between dental and facial indexes and to evaluate whether there is a golden ratio and its relationship with the proportions measured. In this cross-sectional study, digital images of 34 female and 30 male dental students were taken at maximum smile in a similar manner. Then the images were assessed with Photoshop CS5 and ACDSee computer programs and measurements were made with AutoCAD 2011 software. Data was analyzed with independent t-test and means were compared with a constant. The entire variable means did not demonstrate any significant differences between males and females [p value > 0.05]. The inter-pupillary to inter-canine distance ratio did not reveal any significant differences with the golden proportion of 1.618 between males and females [p value > 0.05]. Only the ratios of inter-pupillary, inter-canthus and inter-zygomatic distances to maxillary central widths in females, and the ratios of inter-zygomatic and inter-alar distances to maxillary central widths in males were not significant. Under the limitations of the present study, it was concluded that dento-facial proportions are not significantly different between males and females and the golden ratio applies in the inter-pupillary to apparent width of anterior maxillary teeth proportion. Facial indices are appropriate measures to measure the apparent width of anterior maxillary teeth and can be used as a standard for Iranian dentists and surgeons
Subject(s)
Humans , Male , Female , Maxilla , Students, Dental , Cross-Sectional Studies , FaceABSTRACT
Shear bond strength is one of the most important mechanical characteristics involved in clinical durability of tooth-colored restorations, which is directly related to polymerization shrinkage. This study evaluated the efficacy of two light-curing units [LED2 and QTH] and two types of dentin bonding agents [Excite and Clearfil SE bond] on composite resin shear bond strength to dentin. Forty caries-free sound human premolars were randomly divided into 4 groups of 10 after being disinfected with sodium hypochlorite. The occlusal surface of dentin in each specimen was exposed and flattened by a fissure bur; composite resin was bonded with Excite or Clearfil SE bonding agents and polymerized with QTH or LED2. Shear bond strength values of the specimens were tested in a Dartec universal testing machine. Data were analyzed by one-way ANOVA, two-way ANOVA and Dunkan test [? = 0.05]. Maximum shear bond strength values were recorded in composite restorations bonded with Clearfil SE bonding agent and polymerized by LED2; minimum values were recorded in composites restorations bonded with Excite and polymerized by QTH. Statistical analysis showed statistically significant differences between the experimental groups [p value = 0.03]. Under the limitations of this study, it can be concluded that two curing systems of LED2 and QTH are equally effective on shear bond strength of different bonding agents, whereas Clearfil SE bonding agent produces higher shear bond strength than Excite total-etch regardless of the type of light-curing unit
ABSTRACT
The production of smear layer during canal instrumentation is thought to increase coronal microleakage even after canal obturation. Previous studies have shown that the type of irrigant does not necessarily affect the seal of the obturation. Our study aimed to evaluate the effect of three irrigation solutions [MTAD, citric acid and EDTA/NaOCl] on the coronal microleakage of root canals. Fifty five intact single rooted teeth were instrumented and randomly divided into three experimental groups [15 teeth each] and two control groups [5 teeth each]. Final irrigation was carried out with MTAD in group I, citric acid in group II, and EDTA/NaOCl in group III. EDTA/NaOCl was used for the negative control group and saline irrigation was carried out in the positive control group. After lateral compaction with gutta-percha, the access cavities of the experimental specimens were restored with temporary restorative material. Temporary cement was not used in the positive control group. In the negative control group, access cavities and foramen apices were sealed with glass ionomer. Microleakage of samples was measured using the dye penetration technique. Data were analyzed with ANOVA and Tukey test to determine statistical differences between groups. MTAD, citric acid and EDTA/NaOCl all had less microleakage compared to normal saline. However, no difference was detected between the experimental groups. In this study, all three groups demonstrated effective seal with gutta-percha obturation. This is likely to be due to various factors including their ability to remove smear layer