JOURNAL OF ISLAMIC DENTAL ASSOCIATION OF IRAN (MAJALLAH-I-DANDANPIZISHKI)
Year:2011 | Volume:23 | Issue:2 (79)|Papers Count:12

Background and Aim: The reported bond strengths of resin cements to metal alloys depend on the metal used, the conditioning methods and the adhesive resins. The aim of this study was to evaluate the bond strength of resin cements to two alloys (Degubond 4 and Verabond) after sandblasting or using Silano-Pen.Materials and Methods: Eighty disk shaped specimens (6mm diameter and 2mm thickness) of Verabond or Degubond 4 were cast according to the manufacturer' s instructions. After mounting in auto polymerizing acryl, all samples were polished with a 600 grit silicon carbide paper under water. Half of each alloy’s samples were randomly sandblasted with 50 µ Al2O3 and the other half were flamed with Silano-Pen device after sandblasting with 110 µ Al2O3. Cylinders of composite resin (Z250) were cured and then cemented to the prepared substrates by either Panavia F2 or RelyX Unicem. All specimens were stored in distilled water at 37oC for 24 hours and were subjected to 2000 thermal cycles (5-55oC), then submitted to shear bond strength (SBS) test using Universal Testing Machine at 0.5mm/min speed, until failure. SBS was analyzed by three way ANOVA (a=0.05). Failure patterns were determined using stereomicroscope with 40X magnification.Results: Both cements provided stronger bond to Verabond compared to Degubond 4 (p<0.001). Comparing the surface treatments, Silano-Pen provided higher SBS of RelyX Unicem to both alloys. Panavia cement resulted in higher bond strengths to sandblasted Verabond alloy (p=0.003), but after treatment with Silano-Pen device RelyX Unicem showed higher bond (p=0.011).Conclusion: When cementing Verabond or Degubond 4 by RelyX Unicem, Silano-Pen provided a stronger bond, but in case of using Panavia F2, treatment with Silano-Pen or sandblast resulted no difference in bond strength.

Background and Aim: Different alternative surface treatments, which have not been fully investigated, have been suggested to improve bonding to zirconia. The aim of this study was to compare microtensile bond strength of self- adhesive resin luting cements to zirconia following different surface treatments.Materials and Methods: Three blocks of zirconia (Cercon, Degussa, Germany) and three composite blocks (Z100, 3M, ESPE, USA) with 11×11×5 mm dimension were made. The blocks were divided into three groups. The ceramic blocks were cemented to the composite blocks using G-Cem (GC, Japan) according to the manufacturer’s specifications. All samples were stored in 37°C distilled water for 24 hours and later sectioned in two axes using diamond disk to obtain bar shape specimens with a cross-sectional area of approximately 1mm2 and 10mm long (n=12). Specimens were stored in 37°C distilled water for 72 hours and thermocycled for 2000 cycles (5°C/55°C). Each specimen was then attached to a microtensile test device. Bond strength was measured with crosshead speed of 1mm/min. Failure modes were examined under stereomicroscope (×40). Representative specimens were observed by scanning electron microscopy (SEM). Bond strength data were analyzed with one way ANOVA and Tukey tests (a=0.05).Results: Alloy Primer subgroup (49.64±7.02) had a significantly higher bond strength than silane (42.12±4.2) and silicoating with silanopen (21.78±4.7) (p<0.0001). Silanopen had the lowest bond strength in this group.SEM observation indicate that ceramic surface in silanopen group had fewer irregularities.Conclusion: Primers containing MDP functional monomer like Alloy Primer affect the durability of self adhesive resin cement (G-Cem) bond strength to zirconia.

Background and Aim: The alterations of the RANKL/OPG system and the relationship between diabetes and periodontitis have been implicated in several studies. This study aimed to evaluate the relationship between salivary RANKL and OPG concentration and periodontitis in patients with type 1 diabetes.Materials and Methods: Upon obtaining un-stimulated whole saliva samples from 50 volunteers including 27 type 1 diabetic patients, of whom 12 had periodontitis and 23 systemically healthy subjects, of whom 12 had periodontitis, clinical periodontal measurements were recorded. Statistical analysis was performed using Kruskal-Wallis, Mann-Whitney U test and Spearman correlations.Results: Although lowest RANKL and OPG concentration and their relative ratio were observed in diabetic patients without periodontitis, there was no significant difference in RANKL and OPG concentration and RANKL/OPG ratio between the four groups of the study, but OPG concentration and RANKL/OPG ratio correlated positively with the duration of diabetes (p<0.05). In comparison of the two groups of diabetic patients (with or without periodontitis), there was a significant difference in OPG concentration (p<0.05). There was also a positive correlation between CAL and RANKL concentration (p<0.01) and RANKL/OPG ratio (p<0.05) in diabetic patients with periodontitis.Conclusion: Based on the limitation of the study, it seems that OPG level and OPG/RANKL ratio may serve as indicators of periodontal destruction in type 1 diabetes.

Background and Aim: In recent years with the introduction of laser in dentistry, numerous researches have been conducted to evaluate its efficacy for improving resin material bond on the enamel and dentin. Based on the available literature, no research has been performed on resin shearing bond strength by preparing the tooth surface with YSGG laser on the enamel of the primary teeth. The present study seeks to determine and compare resin shearing bond strength between two groups of surface preparation with acid etch and laser.Materials and Methods: Twenty primary canine teeth which were extracted for orthodontic purposes were collected and were halved with a diamond disc. Each of the halves was mounted in transparent acrylic resin. The teeth were then randomly divided into two groups; in group 1, surface preparation was done with YSGG laser and in group 2, the teeth were prepared with acid etching. Next, the composite was put on the tooth surface by a plastic matrix and cured. The shearing bond strength was measured with instron. The collected data were analyzed using Student’s t-test and Kolmogorov-Smirnov statistical methods.Results: The average bond strength was 27.87 ± 6.136 mpa in the laser group (group 1) and 21.55 ± 5.62 mpa in the acid etch group (group 2) demonstrating a statistically significant difference between the two groups (p<0/05).Conclusion: It may be concluded that resin bond strength is significantly higher in group 1 (YSGG group) compared with Group 2 (acid etch group).

Background and Aim: Formocresol is a popular pulpotomy medicament in primary dentition. Because of its systemic and local side effects, it may be essential to use another material instead of formocresol. The purpose of this study was to assess the pulpal response after pulpotomy histologically with two different agents; namely, formocresol and SUAB2.Materials and Methods: In this randomized clinical trial study, 14 teeth of seven children that should had been extracted because of orthodontic treatment were selected. These teeth were randomly divided into two formocresol and SUAB2 (Shahed University Anti Bleeding2) groups. Seven teeth were pulpotomized with formocresol and seven teeth with SUAB2. These teeth were extracted after 2 months and the pulpal response was evaluated. Finally, the data were analyzed with exact fisher and Mann-Whitney tests.Results: In the formocresol group, severe inflammation was seen in four teeth, mild inflammation in three teeth, abscess in four teeth, necrosis in two teeth, fibrosis in three teeth and internal resorption in four teeth.In the SUAB2 group, severe inflammation was not seen. Moderate and mild inflammation was seen in four teeth, abscess in two teeth, necrosis in two teeth, fibrosis in three teeth and internal resorption in four teeth.Mann-Whitney test revealed that inflammation is significantly less in the SUAB2 group compared with the formocresol group (p<0/05).Conclusion: Based on the results of this study, SUAB2 may be used in primary teeth pulpotomy.

Background and Aim: Detection of caries in early stages is necessary for prevention and conservative treatment. The aim of this study was to evaluate the accuracy of laser fluorescence (LF) using DIAGNOdent pen and to compare it with conventional Bite-Wing (BW) and Digital Radiography (DR).Materials and Methods: In this survey, eighty extracted molars and premolars were mounted in stone blocks to simulate contact points. Proximal surfaces of each tooth were examined with LF. The teeth were also diagnosed using BW and digital radiography. After these procedures, the teeth were histologically prepared and assessed for caries extension as the gold standard. Sensitivity, specificity, positive and negative predictive values and accuracy were calculated for each diagnostic system in comparison with the gold standard. Cut-off points were calculated with ROC analysis. Comparisons between the accuracy of methods were performed using McNemar test.Results: At dentinal caries, LF had the highest sensitivity and specificity (0.82 and 0.84, respectively). For detection of early inter proximal caries, the sensitivity of LF (0.74) and specificity of DR (0.95) were the highest. The LF positive predictive values were the least and negative predictive values were the most. There was no significant difference between conventional and digital radiography in the detection of interproximal caries.Conclusion: DIAGNOdent might be a useful additional tool in detecting early interproximal caries, but due to the false positive responses at decision making for restorative treatments, auxiliary methods should be used.

Background and Aim: Simplification of the self-etching process may affect durability; therefore, long-term durability of these systems in oral conditions has been attended. The aim of this study was to evaluate the effect of 6-month water storage on microleakage of two-component self-etch adhesive systems and to compare these systems with etch and rinse adhesive systems in class V cavities.Materials and Methods: In this in-vitro study, class V cavities were prepared at buccal and lingual surfaces of ninety-six human molars and the enamel margin was beveled (0.5 mm width). The teeth were randomly assigned into four groups (N=24). Twelve teeth were assessed after one day and 12 after 6 months. The adhesive groups were scotch bond multi-purpose, single bond, clearfil SE bond and all-bond SE.After thermocycling, immersion in dye solution and sectioning, the samples were examined using a stereomicroscope. The data were analyzed by Kruskal-Wallis, Dunn, Mann-Whitney U and Wilcoxon tests (p<0.05).Results: In the one day samples, A-B SE adhesive system showed higher microleakage at the occlusal margin (p<0.05). However, there was no significant difference between four adhesive systems at the gingival margin. In the 6-month samples there was no significant difference between four adhesive systems at the occlusal margin, while at the gingival margin etch and rinse adhesive systems (SMP and SB) presented significantly higher microleakage (p<0.05).Conclusion: Pass of time did not affect microleakage of the self-etch adhesive systems at the gingival margin.

Background and Aim: In patients with complete denture, some clinicians have used modelling plastic impression compound (MPIC) along tissue conditioner (TC) materials simultaneously. Little information is available on the composition of these materials and the interaction between them. The purpose of this study was to evaluate the influence of two components of MPIC on the structure and chemical composition of TC.Materials and Methods: In this experimental study, MPIC specimens were provided in 25×2 mm discs. Specimens were randomly divided into three groups and were immersed in ethanol 70%, plasticizer (dibutyl phthalate) and a mixture of them (ethanol 70% and dibutyl phthalate). All of the discs were weighed with a digital balance before and 2, 4, 6 and 24 hours after immersion. Values were analyzed by non parametric Kruskal-Wallis (a= 0.05) and SPSS 16 for Windows (SPSS Inc., Chicago, IL) was used for statistical analysis.Results: Statistical analysis indicated significant differences among all groups (p>.05).Conclusion: Dibutyl phthalate (DBP) had high impact on the solubility of MP, while the mixture of dibutyl phthalate (DBP) and ethanol demonstrated the highest impact.