Ultrasonic vibration and thermo-hydrodynamic technique for filling root canals: Technical overview and a case series.

AIM: To present a novel root canal filling technique: Ultrasonic Vibration & Thermo-Hydrodynamic Obturation (VibraTHO), and its rationale with a series of cases. SUMMARY: The VibraTHO technique was used to fill the root canals of three clinically challenging cases: A C-shaped mandibular molar with complex anatomy, a C-shaped mandibular molar with an infected root canal system and a periapical lesion that required retreatment, and apically bifurcating mesiobuccal canals with a common orifice in a maxillary second molar. The cases were followed up for 15, 7 and 37 months, respectively. After follow-up, normal periapical status was observed without any noticeable radiographic change in the root canal fillings in each case. Periapical radiographs revealed complete healing of the periapical area in cases with pre-operative periapical lesions.

Improvement of water quality at Dongbin Harbor with construction of an inland canal, Korea.

The behaviors of the water body of Dongbin Harbor located at Pohang City, Gyongpook Province, in Korea were numerically simulated in this study. A canal was planned to connect the harbor and the Hyeongsan River to improve water quality inside the harbor. The current system was first simulated by using a commercial program RMA2, with respect to both tidal currents and river flow. The progress inside the harbor from a supply of fresh water from the Hyeongsan River was then predicted by using RMA4. Both the present and future conditions (before and after construction of an inland canal) were taken into consideration in numerical simulations. It is concluded that the water quality inside the harbor can be improved considerably after construction of the canal.

Numerical study on tsunami hazard mitigation using a submerged breakwater.

Most coastal structures have been built in surf zones to protect coastal areas. In general, the transformation of waves in the surf zone is quite complicated and numerous hazards to coastal communities may be associated with such phenomena. Therefore, the behavior of waves in the surf zone should be carefully analyzed and predicted. Furthermore, an accurate analysis of deformed waves around coastal structures is directly related to the construction of economically sound and safe coastal structures because wave height plays an important role in determining the weight and shape of a levee body or armoring material. In this study, a numerical model using a large eddy simulation is employed to predict the runup heights of nonlinear waves that passed a submerged structure in the surf zone. Reduced runup heights are also predicted, and their characteristics in terms of wave reflection, transmission, and dissipation coefficients are investigated.

Physicochemical and rheological properties of ultrasonic-assisted pregelatinized rice flour.

This study evaluated the physical and rheological properties of whole rice flour treated for different sonication times (0-15 min). Ultrasonication reduces the particle size of rice flour and improves its solubility. Viscosity tests using RVA and steady shear showed a notable decrease in the viscosity of the rehydrated pregelatinized rice flour. Although no unusual patterns were observed in the XRD analysis, the FT-IR and microstructure morphology findings suggest that ultrasonication led to structural changes in the rice flour. Overall, the study indicates that ultrasonication is a practical and clean method for producing plant-based drinks from rice flour, which could expand its limited applications in the beverage industry.

Comparison of Root Filling Quality of Two Types of Single Cone-Based Canal Filling Methods in Complex Root Canal Anatomies: The Ultrasonic Vibration and Thermo-Hydrodynamic Obturation versus Single-Cone Technique.

This study aimed to assess the effectiveness of ultrasonic vibration and thermo-hydrodynamic obturation (VibraTHO) using two types of root canal sealers, in comparison to the single-cone (SC) technique and a calcium silicate-based root canal sealer in complex root canal anatomies. Thirty single-rooted human maxillary premolars with two canals that had a complex root canal anatomy of transverse anastomoses or ramifications were prepared and assigned to the following three experimental groups, according to the filling method: SE group, SC technique with Endoseal TCS; VE group, VibraTHO with Endoseal TCS; and VG group, VibraTHO with GuttaFlow 2. Each tooth was scanned using micro-computed tomography, and the volume percentages of the filling material were calculated. The analysis of variance was used to analyze the statistical differences between the three groups (p < 0.05). The mean volume of the filling material was higher in the VG and VE groups than that in the SE group (p < 0.05) along the apical to middle-to-coronal thirds, and significant differences were observed between each root canal area (p < 0.05), with the only exception being at the apical thirds between the VE and SE groups. The VibraTHO technique using GuttaFlow 2 can be a more effective root canal filling method for anatomically complex root canal systems than the SC technique with Endoseal TCS. On the other hand, the VibraTHO technique using Endoseal TCS has a limited effect on improving the quality of the root filling at the apical portion of anatomically complex root canal systems, compared to the SC technique with Endoseal TCS.

Complete Healing of a Large Cystic Lesion Following Root Canal Treatment with Concurrent Surgical Drainage: A Case Report with 14-Year Follow-Up.

We describe complete healing of an extensive cystic lesion by using a conservative approach: root canal treatment with concurrent surgical drainage. A silicone Foley catheter drain was modified into a surgical drainage stent, which was then used for 4 weeks. Disinfection of the root canal was achieved by the use of hand files and irrigation with 5.25% NaOCl for a minimum of 30 minutes. The irrigant changes were performed at 5-minute intervals, and no intracanal dressing was used. At subsequent follow-up examinations, cone-beam computed tomography and periapical radiographs confirmed that complete healing had occurred around the periapical and lateral areas of affected teeth. This case report indicates the potential for healing of large cystic lesions by nonsurgical root canal treatment.

The linear shrinkage and microhardness of packable composites polymerized by QTH or PAC unit.

This study evaluated the effectiveness of a plasma arc curing (PAC) unit for packable resin composite curing. The amount and speed of polymerization shrinkage and the microhardness of packable composites were evaluated in order to compare the PAC unit's effectiveness with a quartz tungsten halogen (QTH) unit. Sure Fil (Dentsply Caulk), Pyramid (BISCO Inc) and Synergy Compact (Colténe/Whaledent) were used as the packable composites. In the case of curing with the PAC unit, the composites were light cured with Apollo 95E (DMD System Inc) for 1 second (Group 1), 2 seconds (Group 2), 3 seconds (Group 3), 6 seconds (Group 4) and 12 seconds (Group 5). For light curing with the QTH unit, the composites were light cured for 60 seconds using XL3000 (Group 6). The linear polymerization shrinkage of each composite was measured using a custom made linometer, and the data was stored in a computer every 0.5 to 0.55 seconds for a total of 60 seconds. For each composite, the amount of polymerization was compared using one-way ANOVA with Tukey at the 95% confidence level. In order to compare the speed of polymerization, the peak time (PT), showing the highest speed of polymerization and maximum speed of polymerization (Smax), were determined from the data and compared using one-way ANOVA with Tukey at the 95% confidence level for each material. Based on the statistical analysis among the PAC-cure groups (Groups 1 through 5), the group that was not statistically different from the QTH-cure group (Group 6) in the amount of linear polymerization shrinkage was determined for each material, and the corresponding curing time of the group was defined as the tentative minimum PAC-curing time (TMPT). For microhardness measurements, the samples were placed in a 2-mm thick Teflon plate. Twenty specimens, randomly divided into the PAC-cure group (Group 1) or the QTH-cure group (Group 2), were prepared for each material. In Group 1, each composite was light cured for TMPT with the PAC unit. In Group 2, each composite was light cured for 60 seconds with the QTH unit. Microhardness was measured on the upper and lower surface. For each material, the microhardness of the upper and lower surface of Groups 1 and 2 was analyzed using two-way ANOVA with Tukey at the 95% confidence level. The amount of polymerization was Group 1

Comparison of linear polymerization shrinkage and microhardness between QTH-cured & LED-cured composites.

This study evaluated the effectiveness of second generation light emitting diode (2ndLED) units in composite curing. In order to compare their effectiveness with that of conventional quartz tungsten halogen light curing units (QTH) and first generation LEDs (1stLED), the amount of linear polymerization shrinkage, polymerization speed and microhardness were measured. Linear polymerization shrinkage was measured every 0.5-0.55 seconds for 60 seconds when composite specimens (Z250, 3M ESPE Dental Products, St Paul, MN, USA) were light cured with five different light sources: XL 3000 (QTH, 3M ESPE Dental Products), Elipar FreeLight 2 (2ndLED, 3M ESPE Dental Products), Ultra-Lume LED2 (2ndLED, Ultradent Products, South Jordan, UT, USA), Elipar FreeLight (1stLED, 3M ESPE Dental Products) and experimental product X (1stLED, Biomedisys, Seoul, Korea). The amount of linear polymerization shrinkage in 60 seconds and the speed of polymerization shrinkage in the first 15 seconds were measured for the different lighting units. The amount of polymerization was compared with one-way ANOVA using Tukey at the 95% confidence level. In order to compare the speed of polymerization, the peak time (PT) showing the highest speed of polymerization and maximum speed of polymerization (Smax) were determined from the data and compared using one-way ANOVA with Tukey at the 95% confidence level for each material. For microhardness measurements, the microhardness of 2-mm composites, Z250, which had been light cured by XL 3000 (G1), FreeLight 2 (G2), Ultra-Lume LED2 (G3), FreeLight (G4) or experimental product X (G5) were compared on the upper and lower surface. The microhardness of each surface was compared between groups using two-way ANOVA with Tukey test at 95% levels of confidence. The amount of polymerization shrinkage at 60 seconds was G1, G2, G3> G4, G5 (p<0.05). PT was G1, G3 G3 >G4, G5 (p<0.05). On the upper composite surface, there was no difference in microhardness between groups (p<0.05). On the lower surface, the microhardness was G1, G2> G3> G4, G5 (p<0.05). There was no difference in microhardness between the upper and lower surface in G1 and G2; whereas, microhardness of the lower surface was lower in G3, G4 and G5. It was concluded that 2ndLEDs and the conventional QTH unit cu red composites moreeffectively than 1stLEDs.

Computed tomography as a diagnostic aid for extracanal invasive resorption.

A case of multiple extracanal invasive resorption is reported. The patient had a history of hypothyroidism for approximately 1 yr before the dental visit. Utilization of computed tomography and a rapid prototyping tooth model in diagnosing the exact location and the size of the resorption area are discussed.

Curing units' ability to cure restorative composites and dual-cured composite cements under composite overlay.

This study compared the efficacy of using conventional low-power density QTH (LQTH) units, high-power density QTH (HQTH) units, argon (Ar) laser and Plasma arc curing (PAC) units for curing dual-cured resin cements and restorative resin composites under a pre-cured resin composite overlay. The microhardness of the two types of restorative resins (Z100 and Tetric Ceram) and a dual-cured resin cement (Variolink II) were measured after they were light cured for 60 seconds in a 2 mm Teflon mold. The recorded microhardness was determined to be the optimum microhard-ness (OM). Either one of the two types of restorative resins (Z100, Tetric Ceram) or the dual cured resin cement (Variolink II) were placed under a 1.5-mm thick and 8 mm diameter pre-cured Targis (Vivadent/Ivoclar AG, Schaan, Liechtenstein) overlay. The specimens that were prepared for each material were divided into four groups depending upon the curing units used (HQTH, PAC, Laser or LQTH) and were further subdi-vided into subgroups according to light curing time. The curing times used were 30, 60, 90 and 120 seconds for HQTH; 12, 24, 36 and 48 seconds for the PAC unit; 15, 30, 45 and 60 for the Laser and 60, 120 or 180 seconds for the LQTH unit. Fifteen specimens were assigned to each sub- group. The microhardness of the upper and and lower composite surfaces under the Targis overlay were measured using an Optidur Vickers hardness-measuring instrument (Göttfert Feinwerktechnik GmbH, Buchen, Germany). In each material, for each group, a three-way ANOVA with Tukey was used at the 0.05 level of significance to compare the microhardnesses of the upper and lower composite surfaces and the previously measured OM of the material. From the OM of each material, 80% OM was calculated and the time required for the microhardness of the upper and lower surface of the specimen to reach 100% and 80% of OM was determined. In Z100 and Tetric Ceram, when the composites were light cured for 120 seconds using the HQTH lamp, microhardnesses of the upper and lower surfaces reached OM. When they were cured with the PAC unit, only 48 seconds was needed for the upper and lower surfaces to reach OM. When they were cured using the laser, the lower surface did not reach OM in any of the groups. When the specimens were cured using the LQTH lamp, 180 seconds of curing was needed for Z100 to reach OM, whereas Tetric Ceram did not reach OM. In Z100, 60, 12, 30 and 60 seconds were needed in HQTH, PAC, Laser and LQTH, respectively, for the specimens to reach 80% OM. Tetric Ceram was needed 60,24,45 and 180 seconds to reach 80% OM. In the Variolink II specimen, microhardness of the upper and lower surfaces did not reach OM even though they were light cured with the HQTH lamp for 120 seconds. When they were cured with the PAC unit, 48 seconds was insufficient for them to reach OM. When they were cured with laser for 45 and 60 seconds, microhardness reached OM on the upper surface but not on the lower surface. However, when they were cured using the LQTH lamp, microhardness did not reach OM on the upper and lower surfaces even though the curing time was extended to three minutes. In Variolink II, 120, 36, 45 and >180 seconds were needed in HQTH, PAC, Laser and LQTH, respectively, for the specimens to reach 80% OM. In conclusion, the PAC system is the most effective curing system to cure the restorative composite and dual cured resin cement under the 1.5 mm Targis overlay, followed by the laser, HQTH and LQTH units. In addition, the restorative composites cured more efficiently than the dual-cured resin cements.