Effect of Temperatures on Polymerization Stress and Microleakage of Class V Composite Restorations

The loss of interfacial integrity was identified as one of the major causes for replacement of resin composite restorations. Preheating procedure has been proven to enhance flowability and adaptation of resin composites and increase their degree of conversion. The purpose of this study was to investigate polymerization contraction stress produced in resin composites after preheating to 37℃ and 60℃, and measure microleakage of Class V restorations restored with preheated composites. Three resin composites (GC Kalore, Gradia Direct X, Filtek Supreme XT) at room temperature, 37℃, and 60℃ were investigated. Maximum contraction stress of the composites (n = 5) was evaluated in a modified low-compliance device. Samples were light-cured for 40 seconds and the maximum force was recorded during 15 minutes. Calculations were done to adjust for the system’s compliance and obtain linear shrinkage values of composites. Data were analyzed by Multivariated Analysis of Variance (MANOVA) and Tukey’s test for multiple comparisons (α = 0.05). Seventy-two Class V cavities were prepared on the buccal surfaces of extracted premolars and divided into 9 groups. The teeth were restored with composites at 3 temperatures and were thermo-cycled between 5℃ and 55℃ with a one-minute dwell-time for 1000 cycles. The teeth were sealed with wax and nail vanish before placed in 0.5% toluidine blue dye for 24 hours. The teeth were embedded in self-curing resin and sectioned bucco-lingually with a slow-speed diamond saw, providing 3 sections per restoration. Microleakage was rated by two evaluators using a 0 - 4 ordinal scale at the occlusal and cervical margins under light microscope. Microleakage data were analyzed with Kruskal-Wallis ANOVA and Mann-Whitney U test (α = 0.05). Results indicate that preheating composites to 37℃ and 60℃ significantly increased polymerization contraction stress of composites (p 0.05). A significantly greater amount of leakage was found at the cervical margins (p 0.05). For all tested materials, preheating composites to 60℃ resulted in significantly less microleakage at the cervical margin.

^(99m)Tc in the evaluation of microleakage of composite resin restorations with SonicFill^(TM).An in vitro experimental model

Introduction: The composite SonicFillTM (Kerr/Kavo) is indicated for posterior restorations, with a single increment up to 5 mm due to reduced polymerization shrinkage, thus reducing working time. Aim: Evaluation of marginal microleakage with SonicFillTM. Method and Materials: There were sectioned sixty noncarious human molars in the occluso-cervical direction. Class V cavities were prepared on each tooth with gingival margin walls in a standardized way. The specimens were divided into 4 groups: group 1—restored with SonicFillTM (Kerr/Kavo), group 2—restored with FiltekTM SupremeXTE (3M ESPE), group 3—the cavities were not restored;group 4—restored with SonicFillTM (Kerr/Kavo). In groups 1, 2 and 4 the enamel was conditioned with 37% orthophosphoric acid and applied the self-etch adhesive system Clear- fillTM SE BOND (Kuraray). The specimens were stored in distilled water at 37?C for 7 days. After, the specimens, were immersed in a solution of 99mTc-Pertechnetate and the radioactivity was assessed with a gamma camera. The nonparametric Kruskal-Wallis and Mann-Whitney test with Bonferroni correction at a significance level of 5% were used for the statistical analyses. Results: There are significant differences between the positive and negative control groups and between these and experimental groups (p TM and FiltekTM SupremeXTE. Conclusion: The new composite SonicFillTM and FiltekTM SupremeXTE showed no difference concerning dye penetration. The Sonic- FillTM restorative system showed no influence in concerning microleakage.

Comparison of resin composite restorations microleakage: An <i>in-vitro</i>study

The aim of this study was to compare the microleakage of total-etch and self-etch adhesives by three methods including dye extraction, dye penetration and fluid filtration with determining the correlation value among these techniques. Seventy-two premolar teeth were selected for this in vitro study and Class 5 cavities were prepared on the buccal surface of these at the cementoenamel junction area. It was applied for half of these cavities, Optibond Solo Plus (OSP) (two-step etch & rinse) and another half, Optibond All-in-One (OA) (one-step self-etch) and then all of them were restored with a light cure resin composite;Herculite XRV. Then samples were divided randomly into three subgroups based on the method of microleakage measurement (n = 12). In the first pair group, leakage was assessed by the dye extraction method. Dye penetration and fluid filtration methods were used in the second and third pair groups for the same purpose respectively. Data were analyzed by Paired t-test and Wilcoxon test and correlation coefficients (α = 0.05). There was no significant difference in the dye extraction (P = 0.657) and dye penetration (P = 0.732) methods between the microleakage of total-etch and self-etch adhesives. Microleakage of self-etch adhesive in fluid filtration technique was significantly more than total-etch adhesive (P = 0.012). No significant correlation was found among the results obtained with the three methods of microleakage evaluation. Adhesive systems showed variously behave in different methods of microleakage assessment.

Marginal discrepancy and microleakage in crown-copings fabricated by three CAD/CAM systems: An <i>in vitro</i>study

The purpose of this study was to evaluate and compare the microleakage and marginal discrepancy of ceramic crown-copings fabricated by three different CAD/CAM systems. Material and methods: Thirty extracted premolars were prepared for complete all-ceramic crowns with: total convergence 10-degree, 2 mm occlusal reduction, 4.5 mm height, 1.3 mm circular reduction and chamfer marginal preparation. They were divided into three groups and each group (n = 10) received a ceramic crown-coping fabricated by one of three CAD/CAM systems: Procera, KaVo Everest and Cerec inLab. The copings were cemented with Panavia F 2.0. After thermal cycling, the teeth were immersed in 2% basic fuchsine dye for 24 hours. Microleakage was scored using a five-point scale and evaluated under a stereomicroscope at ×18. Marginal discrepancies were assessed with scanning electronic microscope at ×150, with measurements at 50 different points. Data were subjected to a chisquare test, Kolmogorov-Smirnov test and using Rho Spearman’s correlation test (P 0.05). No significant differences were found in marginal discrepancies for the Procera (62.58 ± 8.98 μm) and KaVo Everest systems (65.54 ± 18.56 μm), (P = 0.941). Significant differences were found for Cerec inLab (132.18 ± 27.75 μm) compared with Procera and KaVo Everest (P = 0.0001). No correlation between the marginal discrepancies and microleakage for the three CAD/CAM crown-copings systems. Conclusions: Cerec inLab CAD/CAM crown-copings showed significantly higher values for microleakage and marginal discrepancy in comparison with Procera and KaVo Everest CAD/CAM crown-copings.

Microleakage of Nanofilled Composite Resin Restorative Material

The role of nanofillers in reducing the microleakage of dental composite resins has not been previously investigated. So this study was designed to evaluate microleakage of nanofilled composite resin in comparison to the conventional hybrid composite. Twenty extracted sound molars were selected. Class II cavities were prepared. All cavities were etched (enamel and dentin) with 37% phosphoric acid. Dentin bonding agents were applied to etched tooth surfaces and restored with nanofilled and hybrid composite restorative materials. The restored teeth were thermocycled. Specimens were immersed in 2% methylene blue dye, sectioned along the mesio-distal direction;dye penetration of occlusal and gingival margins of each section was evaluated using a stereo-microscope. No significant difference was found between the microleakage of nanofilled and hybrid composite restorations at occlusal / enamel and at gingival / dentin margins. Also, there were no significant differences for nanofilled composite restorations at occlusal / enamel margins and gingival / dentin margins. On the other hand, there were a significant differences for hybrid composite restorations at occlusal / enamel margins and gingival / dentin margins.

The Effect of Different Filling Methods on the Microleakage of the Tooth Edge after Bulk Resin Filling

Objective:Analyzing the influence of different filling methods on the microleakage of posterior teeth during the treatment of bulk resin filling.Methods:From January 2019 to January 2020,68 patients with posterior tooth filling(123 teeth)in our hospital were selected and randomly assigned into three groups(A,B,and C),with 41 teeth in each group.Group A received bulk posterior teeth filling resin treatment,group B received Charisma®resin filling treatment and group C received FX-Ⅱfilling treatment.The curative effect and microleakage of posterior teeth between the groups were compared.Results:Comparison of treatment efficiency in group A(97.56%),group B(85.37%)and group C(73.17%)shows that P<0.05;comparison of microleakage value and operation time of group A,group B and group C shows that P<0.05.Conclusions:In resin filling treatment,bulk posterior tooth filling resin material should be selected for its high hardness,strong edge adhesion,and natural effects.

Effect of Nanoparticles Reinforced Adhesive Layers on Microleakage of Tooth Restorations

Adhesive layer is an essential part of tooth colored restorations which play an important role in decreasing the microleakage between the tooth and restoration material after polymerization shrinkage. The purpose of this study was to evaluate the effect of deferent adhesive system of bonding agent on microleakage of nanocomposite resin in class II cavities. Two different types of adhesive systems: universal adhesive (ExciTE) and a newly developed adhesive (Nano-Bond) and one type of light-cured resin restorative material (nanocomposite resin) were used in this study. These adhesives were applied to prepared tooth cavities by either manufactures’ instructions or by an experimental method (single or double application). Nanocomposite resin was then placed and light-cured for 40 seconds. Teeth were subjected to 500 thermal cycles between 5&degC and 55&degC and were immersed in 3% methylene blue solution for 24 hours;microleakage was observed microscopically. The data were analyzed by a two-way ANOVA. For comparison between groups, Tukey’s post-hoc test was used. Nanoparticles reinforced adhesive system shows low microleakage in compare with universal adhesive system, and application of two adhesive layers also can decrease the microleakage. The ability of stress absorption by adhesive layer after polymerization shrinkage of restoration material will reduce the microleakage.

MICROLEAKAGE OF CLASS V RESIN-MODIFIED GLASS IONOMER CEMENT AND COMPOMER RESTORATIONS IN VITRO

Objective To assess the microleakage of Class V restorations made with two resin-modified glass ionomer cements （RMGICs） and two polyacid-modified composite resins （PMCRs）. Methods Restorations of the four materials （ GC Fuji Ⅱ LC, Vitremer^TM, Dyract AP and F2000^TM ） were placed in facial Class V cavity preparations in forty noncarious human molar teeth. Teeth were randomly assigned to 4 experimental groups of 10 teeth each. After thermal cycling（ ×20, 5 -55℃ ） , the interface between dentin and restorations was spattercoated with gold and observed under scanning electron microscopy （SEM）. Then the square and average width of margin gaps of central 1/3 interface were recorded with image analysis software. Results The data indicated no significant differences between all the restorative materials for both occlusal and gingival margins. Further analysis revealed there were statistically significant differences between occlusal margins and gingival margins for VitremerTM and Dyract AP, respectively. Conclusion None of the tested materials guaranteed margins free of microleakage. Resin-modified glass ionomer cements showed similar margin gaps to the polyacid-modified composite resins tested.

Exploration and preliminary clinical investigation of an adhesive approach for primary tooth restoration

The current study aims to investigate a suitable adhesive for primary tooth enamel. Shear bond strength(SBS)of primary teeth and the length of resin protrusion were analyzed using one-way ANOVA with Bonferroni multiple comparison tests after etching with 35% H_(3)PO_(4). SBS and marginal microleakage tests were conducted with Single Bond Universal(SBU)/Single Bond 2(SB2) adhesives with or without pre-etching using a nonparametric Kruskal-Wallis test. Clinical investigations were performed to validate the adhesive for primary teeth restoration using Chi-square tests. Results showed that the SBS and length of resin protrusion increased significantly with the etching time. Teeth in the SBU with 35% H_(3)PO_(4)pre-etching groups had higher bond strength and lower marginal microleakage than those in the SB2 groups. Mixed fractures were more common in the 35% H_(3)PO_(4)etched 30 s + SB2/SBU groups. Clinical investigations showed significant differences between the two groups in cumulative retention rates at the 6-, 12-and 18-month follow-up evaluations, as well as in marginal adaptation, discoloration, and secondary caries at the 12-and 18-month follow-up assessments.Together, pre-etching primary teeth enamel for 30 s before SBU treatment improved clinical composite resin restoration, which can provide a suitable approach for restoration of primary teeth.

Quantitative scintigraphic analysis of the apical seal in Thermafil/Topseal and Real Seal 1/Realseal filled root canals

AIM: To investigate the microleakage of two different root canal obturation systems, using the nuclear medicine approach.METHODS: Twenty-six single-rooted extracted teeth were selected. The crowns were sectioned to obtain 15-mm long root segments and each tooth was prepared using rotary Pro File instruments. The roots were divided into 2 experimental groups using Real Seal 1 and Real Seal sealer or Thermafil and Top Seal sealer as well as two control groups. On the 7th and the 28 th day the apices were submersed in a solution of 99 m TcPertechnetate during 3 h. The radioactivity was counted using a γ camera. RESULTS: The present study showed that none of the root canal-filled teeth was leakage free. The statistical analyses were made using Kruskal-Wallis and statistical significance was assessed using α = 0.05. Although apical leakage measured in counts per minute(cpm) in the Thermafil/Top Seal group was lower than in the Real Seal/Real Seal group(363 916 ± 180 707.7 cpm vs533 427 ± 414 020.6 cpm) on 7th day and(1 678 200 ± 567 217.4 cpm vs 2 240 518 ± 383 356.7 cpm) on 28 th day, there was no statistical difference(P > 0.05). In the Thermafil/Top Seal group and Real Seal 1/Real Seal group it was found that over time, the number of counts increased between 7 d and 28 d(363 916 ± 180 707.7 cpm vs 1 678 200 ± 567 217.4 cpm) and(533 427 ± 414 020.6 cpm vs 2 240 518 ± 383 356.7 cpm), respectively, with statistically significant differences(Thermafil/Top Seal group, P = 0.015 and Real Seal 1/Real Seal group, P = 0.036).CONCLUSION:Both carrier-based Realseal 1 and Thermafil techniques showed a similar sealing effect,but none of the materials was leakage free.

Comparison of the apical seal on filled root canals with Topseal^®vs MTA Fillapex^®sealers: A quantitative scintigraphic analysis

This study investigated the microleakage of two different root canal obturation systems, using the nuclear medicine approach, with sodium pertechnetate 99mTc. Twenty six single-rooted extracted teeth were selected. The crowns were sectioned to obtain15 mmlong root segments and each tooth was prepared using rotary ProFile? instruments. The roots were divided into 2 experimental groups and two control groups. Twenty root canals were filled, using Thermafil? and Topseal? or MTA Fillapex? as a sealer. On the 7th and the 28th day the apices were submersed in a solution of 99mTc-Pertechnetate during 3 hours. The radioactivity was counted using a gamma camera. Although apical leakage on the 7th day in the Topseal group was reduced compared with RealSeal1, with a statistical significant difference (p = 0.057), on the 28th day, the MTA Fillapex increased the sealing properties (p = 0.017).

A Comparative <i>In-Vitro</i>Study of Sealing Ability of Four Different Materials Used in Furcation Perforation

The purpose of this study was to compare the sealing ability and marginal adaptation of four re-storative materials (MTA, Biodentine, portlant cement, and resin modified glass ionomer cement) used to repair iatrogenic furcation perforations. Eighty-four molars were treated endodontically, perforated in the middle of the pulp chamber floor with a round bur and separated randomly into 4 groups of 20 teeth each, while 4 teeth were used as positive and negative controls. The teeth were embedded in a moistened flower sponge and the perforations were filled with the appropriate restorative materials: Group 1: Biodentine;Group 2: MTA Angelus;Group 3: GC Fuji lining LC Paste Pak;Group 4: Aquafix Portland cement. The teeth remained in the soaked sponge for 28 days and then were submerged in basic fuchsine solution 1% for 48 hours. Dye penetration was evaluated after longitudinal sectioning of the teeth. Statistical analysis revealed that perforations restored with MTA exhibited the least microleakage with statistically significant difference among the other three groups (p < 0.05). The worst sealing ability was observed in the teeth restored with Aquafix Portland cement. No statistically significant difference was found between the groups of Biodentine and FC Fuji Lining Paste (p = 0.066).

Preparation and Characterization of CaO/ZnO Core-shell Structured Nanoparticles

Residual bacteria and microleakage in a complicated root canal can often result in reinfection of the periapical tissues.To promote the antibacterial and sealing eftects of a root canal filling,core-shell structured CaO/ZnO nanospheres were synthesized using a precipitation method based on a traditional root canal sealer,zinc oxide-eugenol(ZOE).The obtained CaO/ZnO particles had a size of 80—90 nm and a core-shell structure.The film thickness,flow rate,pH,and calcium ion release of the core-shell structured CaO/ZnO nanospheres-eugenol paste were tested.The pH and calcium ion release results showed a slight increase in the prepared nanospheres,with a flow rate of 24.22 mm and a formed film thickness of 30 pm,which are basically consistent with ISO 6876:2001 standards(regarding dental root canal sealing materials).Cytotoxicity tests showed that the cytocompatibility of the CaO/ZnO nanospheres-eugenol paste was much higher than that of the ZOE or iRoot SP groups(P<0.05).A comparison of the sealing ability and antibacterial activity showed that the core-shell structured CaO/ZnO nano spheres-eugenol paste had significantly better effects than the ZOE and iRoot SP sealers(P<0.05).The core-shell structured CaO/ZnO nano sphere paste displayed excellent sealing and antibacterial properties,and it has promising application potential in endodontics.