ABSTRACT
Statement of Problem: Because dental restorations are time consuming, dental material manufacturers make an attempt to discover new methods for rapidity and increasing the quality of restorations. With this objective in mind, plasma arc curing devices have been manufactured
Purpose: This study was done to compare the effect of plasma arc and halogen light curing on the microleakage of class V resin composite
Methods and Material: In this experimental study, on 80 extracted maxillary central teeth, standard class V cavities were prepared with incisal and gingival margins in the enamel and dentin. After etching and bonding, the teeth were randomly divided into two subgroups of 40 and restored with Amelogen composite. In the first group, halogen light curing for 40 seconds was used and in the second one plasma arc curing was used for four seconds. After thermocycling and sealing, the samples were immersed into the 0.5% fuchsine solution for 24 hours and then washed with water and cut. The microleakage was scored by stereomicroscope with 40X magnification. The data were analyzed using Mann-Whitney and Wilcoxon tests
Results: The mean of incisal wall microleakage in the plasma arc group was 1.42+/-0.98 and in the halogen group it was 0.67+/-0.02. The gingival margin in the plasma are group showed a mean of 1.75+/-1.48 and in the halogen group it was found to be 1.67+/-1.54. There were significant differences in the incisal wall [p =0.0001], but not in the gingival wall [p =0.744]. The average rate of microleakage in the gingival and incisal walls in the plasma arc group was 3.17+/-1.79 and in the halogen group it was 2.76+/-1.92; there were not any significant differences between the groups [p =0.32]
Conclusion: In the restorations with enamel margins halogen light curing and in all composite restorations plasma arc curing are preferred due to the short time of curing
ABSTRACT
Statement of Problem: The control of microleakage presents a challenge for posterior composite restorations. The technique for composite placement and treatment technique may cause some modifications in the microleakage. The results of different studies are varied
Purpose: This study aimed to evaluate the marginal microleakage in class II P60 resin composite restorations prepared with two restorative techniques and two polymerization systems
Materials and Method: Standard class II cavity preparations were performed on 56 carries- free extracted molars. Then, the teeth were randomly divided into four groups: 1] Bulk placement and conventional polymerization 2] Incremental placement and conventional polymerization 3] Bulk placement and soft start polymerization 4] Incremental placement and soft start polymerization. All the cavities were restored with single bond and P60 [3M/ESPE] resin composite. After thermo cycling, the specimens were immersed in 2% methylene blue solution for 24 hours and then washed. After sectioning, dye penetration was assessed by light stereomicroscopy at 40x magnification and then evaluated for microleakage by Kruskal-Wallis Test and Mann-Whitney tests
Results: Significant differences were found between the bulk with incremental technique and soft start with conventional polymerization. The highest and lowest rates of microleakage were in bulk conventional and incremental soft start group, respectively. A significant difference was found between groups
Conclusion: The use of incremental placement technique and soft start system results in less microleakage
ABSTRACT
There is limited information available regarding the adhesive ability of resin- modified glass ionomers and polyacid resin modified composites to primary dentin. The aim of this study was to compare the shear bond strength of compoglass with and without phosphoric acid%37 with a resin- modified glass ionomer [Fuji II LC] to primary molars' dentin. In this experimental study, 30 human extracted primary molars were used in this experimental study. The teeth were mounted in stone. After preparation, the specimens were randomly divided into three equal groups [n=10]. In group I, the specimens were bonded with compoglass following the manufacturer's instructions. In group II, after the specimens were etched with phosphoric acid%37, they were bonded with compoglass. In group III, the specimens were bonded with glass ionomer [Fuji II LC]. Shear bond strength was measured for the bonded specimens using an Instron at a crosshead speed of 1mm/minute. The results were analyzed using ANOVA and Tamhane test. The mean value of shear bond strength of compoglass with and without acid was 14.19 +/- 2.47, and 10.20 +/- 2.58 Mpa, respectively. The mean value of shear bond strength of Fuji II LC was 6.11 +/- 1.12 Mpa. There were significant differences between compoglass with and without phosphoric acid and glass ionomer Fuji II LC [p=0.001]. The findings showed that compoglass tested in this study had higher shear bond strength than glass ionomer [Fuji II LC]. Also, the use of acid phosphoric before bonding in compoglass improved the shear bond strength
Subject(s)
Humans , Composite Resins , Glass Ionomer Cements , Compomers , Tooth, DeciduousABSTRACT
Polymerization shrinkage is one of the most common causes of microleakage in packable composites. Various methods are recommended to reduce polymerization shrinkage and the application of flowable composites is one of these methods. The aim of the current study was to evaluate the effect of flowable composite on the microleakage of packable resin composite in class II cavities. This experimental study was performed at Dental School of Shahid Sadoughi University, Yazd [Iran] in 2006. On 32 recently extracted upper premolar teeth, the mesial and distal class II cavities with the same dimensions were created. The teeth were randomly assigned into two groups: the distal surfaces of the first group were restored with P60 while in the other group restoration was accomplished with Solitaire resin composite. The mesial aspects of the teeth were filled with Filtekflow flowable composite and other composites mentioned above. After thermocycling, the samples were soaked in 2% methylene blue solution followed by sectioning in mesiodistal direction. The degree of microleakage was evaluated by stereomicroscope with 25 X magnification. Data were subjected to the chi-square and Exact tests, statistically. The flowable composite failed to reduce the degree of microleakage in axial wall and gingival floors [p>0.05]. The application of flowable resin composite caused no effect on microleakage of class II packable resin composite restorations
Subject(s)
Polymers , Dental CariesABSTRACT
Bonding agents are one of the most important materials in adhesive dentistry. Sixth generation bondings have more simple application than fifth generation, but despite this, it has been addressed by some articles that adhesive strength of sixth generation gradually decreases over time. The aim of this study was to compare the shear bond strength of a resin composite with application of two bonding agents [fifth and sixth generation] after three months storage in normal saline. This invitro study was conducted on 40 anterior bovine teeth. After complete removal of enamels, the samples were randomly divided into four groups based on the use of acid etch technique and the type of bonding agents [Excite or Prompt L-pop]. After applying Z250 composite resin, the samples were immersed in normal saline for 90 days and then were thermocycled and subjected to shear bond testing with Dartec universal testing machine. Statistical analysis was performed using one-way ANOVA and Tukey's test. In non-etched groups, Prompt L-pop showed significant higher bond strength than Exite, but in etched groups Excite had significantly higher bond strength [p<0.005]. There were no significant differences in Prompt L-pop subgroups with or without etching meanwhile in Excite subgroups, significant differences were found. The use of Excite with acid etching technique provide more reliable bonding than Prompt L-pop to dentin