Indirect Ultrasonic Activation Research Articles

Effects of Access Cavity Design and Placement Techniques on Mineral Trioxide Aggregate Obturation Quality in Simulated Immature Teeth: A Micro-Computed Tomography Study.

Background and Objectives: In teeth with open apices, performing single session apexification is a challenging treatment due to the difficulty in handling mineral trioxide aggregate (MTA). Minimally invasive approaches in dentistry have also influenced the cavity designs in endodontics. Until now, different techniques have not been investigated in addition to manual condensation during the process of placing MTA in traditional (TradACs) or conservative (ConsACs) endodontic access cavities. The aim of this in vitro study was to compare and evaluate the obturation quality of MTA apical plugs placed with different techniques in TradACs or ConsACs. Materials and Methods: Sixty upper central teeth were divided into two main groups based on cavity design, and then each main group was further divided into three subgroups according to MTA placement techniques (n = 10): TradAC-manual, TradAC-manual + indirect ultrasonic activation, TradAC-manual + XP-endo Shaper (XPS), ConsAC-manual, ConsAC-manual + indirect ultrasonic activation, and ConsAC-manual + XPS. Subsequently, the porosity percentages in the MTA apical plug were analyzed using micro-computed tomography. The statistical analysis was performed using the Kruskal-Wallis H test and Mann-Whitney U test. Statistical significance was set at p < 0.05. Results: There were differences in volume of porosity percentages (%) according to cavity designs and MTA application techniques (p < 0.05). Except for the XPS group, more porosity was observed in ConsACs compared to TradACs. In TradACs, the significantly lowest open and total porosity was observed in the manual, ultrasonic, and XPS techniques, respectively. In ConsACs, the significantly lowest porosity was observed in the manual, XPS, and ultrasonic techniques, respectively (p < 0.05). Conclusions: In MTA obturation, cavity designs and application techniques had an impact on the MTA porosity. Creating an apical plug in ConsACs may result in more porosity compared to TradACs, especially when manual or indirect ultrasonic activation is preferred. Opting for the manual technique alone may be considered sufficient for controlling porosity for both TradACs and ConsACs.

Micro-Computed Tomographic Evaluation of the Sealing Quality and Bond Strength of Different MTA Apical Plugs

Objective: This study aimed to compared the effects of different placement techniques to the sealing quality of mineral triokside aggregate (MTA) apical plugs at apexification technique by micro-computed tomography (micro-CT) and compared the bond strength to root dentin of an injectable MTA (BIOfactor MTA), MTA Angelus and AH Plus. Methods: Sixty dentinal root slices were obtained from 20 maxillary centrals.A canal-like hole was drilled into each slices canal space.The samples were divided into 3 groups (n=20).All materials were delivered into the holes. Push-out tests were performed and fracture types were analysed with a strereomicroscope. In the second part of the study,72 maxillary central teeth with standardised artificial divergent open apex were divided into 4 groups; MTA Angelus and BIOfactor MTA were mixed mechanically, and introduced to form 4 mm thick apical plugs by hand condensation or indirect-ultrasonic activation for 10 seconds. Incidence of external voids between dentin walls and MTA apical plugs and porosity inside MTA were determined by volumetric analysis with micro-CT. Results: No significantly difference was found between the bond strength values of the materials (p:0.370; p&gt;0.05).The external voids and porous voids are similar in both MTA (p: 0.685; p&gt;0.05).When indirect-ultrasonic activation was applied,there was significantly less porosity statistically than hand condensation (p:0.00; p&lt;0.05). Conclusion: MTA Angelus and BIOfactor MTA materials showed similar results in terms of bond strength to root dentin, fracture types, adaptation to dentin walls and structural porosity rate. Both MTA materials showed less structural porosity when placed by indirect ultrasonic activation technique compared to manual condensation.

Evaluation of the Impact of Calcium Silicate-Based Sealer Insertion Technique on Root Canal Obturation Quality: A Micro-Computed Tomography Study.

Calcium silicate-based sealers have gained in popularity over time due to their physicochemical/biological properties and their possible use with single-cone obturation. The single cone technique is a sealer-based obturation and there is still a knowledge gap regarding the potential impact of the sealer insertion method on the root canal-filling quality. Therefore, the aim of this micro-CT study was to assess the impact of the calcium silicate-based sealer insertion technique on void occurrence and on the sealer extrusion following single-cone obturation. Thirty-six single-rooted mandibular premolars with one canal were shaped with Reciproc® R25 (VDW, Munich, Germany) then divided randomly into four groups of nine canals, each depending on the TotalFill® BC Sealer insertion technique used with single cone obturation: injection in the coronal two-thirds (group A); injection in the coronal two-thirds followed by direct sonic activation (group B); injection in the coronal two-thirds followed by indirect ultrasonic activation on tweezers (group C); sealer applied only on the master-cone (control group D). Samples were then scanned using micro-CT for voids and sealer extrusion calculation. Data were statistically analyzed using v.26 IBM; Results: No statistically significant differences were noted between the four groups in terms of voids; nevertheless, sonic activation (group B) followed by ultrasonic activation on the tweezers (group C) showed the best results (p = 0.066). Group D showed significantly less sealer extrusion when compared with group C (p = 0.044), with no statistically significant differences between groups D, A and B (p > 0.05). Despite no significant differences observed between the different sealer placement techniques, the use of sonic and ultrasonic activation might be promising to reduce void occurrence. Further investigations are needed to demonstrate the potential benefit of calcium silicate-based sealer activation especially in wide and oval root canals in order to improve the quality of the single-cone obturation.

Effect of indirect ultrasonic activation of modified bioceramic materials on the bond strength and tubular penetration in root canals

To maintain the integrity of the interface between root canal filling and radicular dentin an ideal endodontic biomaterial should have good adhesion. This study was aimed to evaluate the bond strength and tubular penetration of modified bioceramic materials by indirect ultrasonic activation. In the present in vitro experimental study, 120 coronal root slices of 2 mm were prepared from mandibular premolars and randomly divided into six groups (n = 20) in accordance to placement techniques: Group I: Nano Biodentine-manual, Group II: CaCl2 modified ProRootMTA-manual (MM), Group III: Biodentine-manual, Group IV: Nano Biodentine: Ultrasonic, Group V: CaCl2 modified ProRootMTA-ultrasonic, and Group VI: Biodentine-ultrasonic (BDU). The samples were kept in humidifier for 4 days at 37°C and push out bond strength, sealer penetration were evaluated using an universal testing machine and confocal laser scanning microscope respectively. Data were subjected to statistical analysis using SPSS software by using One-way ANOVA for overall significance and Tukey's multiple post hoc test for intergroup comparison (P < 0.05). Highest push out bond strength and greater tubular penetration were observed with Group VI (BDU), while the lowest bond strength and tubular penetration were associated with Group II (MM). Within the limitations of current study it was observed that Biodentine with indirect ultrasonic activation has resulted in highest pushout bond strength among all the study groups.

Micro-CT analysis of the marginal adaptation and porosity associated with ultrasonic activation of coronally placed tricalcium silicate-based cements.

This study aimed to evaluate the effect of ultrasonic activation on coronal marginal adaptation and microporosity of tricalcium silicate-based materials. Sixty freshly extracted human maxillary lateral incisor teeth were instrumented with ProTaper Next X2 files followed by Peeso-Reamer burs, sizes 1 to 5. The specimens were randomly divided into six groups (n=10): Group 1, Biodentine+hand condensation; Group 2, Biodentine+ultrasonic activation; Group 3, NeoMTA Plus+hand condensation; Group 4, NeoMTA Plus+ultrasonic activation; Group 5, ProRoot WMTA+hand condensation; and Group 6, ProRoot WMTA+ultrasonic activation. All tested materials were mixed mechanically and placed 2mm underneath the cement-enamel junction by hand condensation or indirect ultrasonic activation. Volumetric analysis of the voids between the dentine wall and coronal barrier material and the porosity within the material was evaluated with micro-CT. There was no significant difference in marginal adaptation among the six groups (P>0.05). Ultrasonic activation favoured a reduced microporosity in Biodentine Group (P<0.001).

Obturation quality of calcium silicate-based cements placed with different techniques in teeth with perforating internal root resorption: a micro-computed tomographic study.

To evaluate and compare the obturation quality of mineral trioxide aggregate (MTA) and Biodentine placed with hand condensation or indirect ultrasonic activation technique in teeth models simulating perforating internal root resorption (IRR) using micro-computed tomographic (micro-CT) imaging. Standardized models with perforating IRR cavities were created using 40 extracted single-rooted human teeth and randomly divided into four groups (n = 10). The specimens were obturated with either MTA or Biodentine and the placement technique applied was either hand condensation or indirect ultrasonic activation. Micro-CT scans were performed for the volumetric analysis of voids and filling materials in the resorption cavities and apical portion of the specimens. Data were analyzed using one-way analysis of variance and paired t test. No significant difference was observed between the groups in terms of the percentage volume of filling materials (p > 0.05). The apical portion of the specimens significantly presented less percentage volume of filling materials than the resorption cavities in each group (p <0.05). No placement technique produced void-free fillings in teeth with perforating IRR. There was no significant difference between the obturation quality of Biodentine and MTA. The obturation quality in the apical portion of the root canals was inferior than that in the resorption cavities. The obturation of the apical region of teeth with perforating IRR is challenging irrespective of the material type and placement technique.

X-ray diffraction analysis of MTA mixed and placed with various techniques.

The aim of this study was to evaluate the effect of various mixing techniques as well as the effect of ultrasonic placement on hydration of mineral trioxide aggregate (MTA) using X-ray diffraction (XRD) analysis. One gram of ProRoot MTA and MTA Angelus powder was mixed with a 0.34-g of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30s at 4500rpm or by manual mixing followed by application of a compaction pressure of 3.22MPa for 1min. The mixtures were transferred into the XRD sample holder with minimum pressure. Indirect ultrasonic activation was applied to half of the specimens. All specimens were incubated at 37°C and 100% humidity for 4days. Samples were analyzed by XRD. Phase identification was accomplished by use of search-match software utilizing International Centre for Diffraction Data (ICDD). All specimens comprised tricalcium silicate, calcium carbonate, and bismuth oxide. A calcium hydroxide phase was formed in all ProRoot specimens whereas among MTA Angelus groups, it was found only in the sample mixed mechanically and placed by ultrasonication. Mechanical mixing followed by ultrasonication did not confer a significant disadvantage in terms of hydration characteristics of MTA. Clinicians vary in the way they mix and place MTA. These variations might affect their physical characteristics and clinical performance. For ProRoot MTA, the mixing and placement methods did not affect its rheological properties, whereas for MTA Angelus, mechanical mixing combined with ultrasonic placement enhanced the calcium hydroxide phase formation.

Comparative Micro–computed Tomographic Evaluation of the Sealing Quality of ProRoot MTA and MTA Angelus Apical Plugs Placed with Various Techniques

IntroductionThis study compared the effects of different mixing and placement techniques on sealing of ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and MTA Angelus (Soluçoes Odontologicas, Londrina, Brazil) apical plugs using micro–computed tomographic (micro-CT) imaging. MethodsStandardized divergent open apex models were created using 120 extracted maxillary incisors and divided into 8 groups (n = 15). ProRoot MTA and MTA Angelus were mixed manually or mechanically and introduced to form apical plugs by hand condensation or indirect ultrasonic activation for 10 seconds. The samples were scanned using micro-CT imaging, and volumetric analysis of the voids between the dentin walls and the apical plugs and the porosity inside MTA was performed. ResultsIrrespective of the mixing and placement techniques used, the voids between the dentin walls and the apical plugs in the MTA Angelus groups were greater than those in the ProRoot MTA groups (P < .05). The mechanically mixed groups were significantly less porous than the manually mixed groups (P < .05). Combined mechanical mixing and indirect ultrasonic activation yielded a less porous structure for both types of MTA than combined manual mixing and hand condensation (P < .05). Marginal adaptation for ProRoot MTA, both mixed and placed manually, was greater than for MTA Angelus (P < .05), but no difference was found when indirect ultrasonic activation was performed (P > .05). ConclusionsProRoot MTA showed better marginal adaptation than MTA Angelus. Mechanically mixed products had better handling characteristics than the manually mixed product. Indirect ultrasonic activation did improve the adaptation of manually mixed MTA Angelus to the dentin walls.

Comparison of Mechanical and Indirect Ultrasonic Placement Technique on Mineral Trioxide Aggregate Retrofill Density in Simulated Root-end Surgery

IntroductionThe objective of this study was to evaluate the density of mineral trioxide aggregate (MTA) root-end filling placed by either manual condensation or manual condensation with indirect ultrasonic activation under simulated root-end surgery conditions in vitro. MethodsExtracted human molar teeth were obtained and sectioned to provide single-rooted samples (n = 50). Roots were instrumented to a size of 40 with a .04 taper and obturated with a warm vertical technique. The coronal end of each root was embedded in resin. A root-end resection and root-end preparation were completed on each root. Samples were randomly assigned to receive root-end fillings with ProRoot MTA (Dentsply, Tulsa, OK) by 1 of 2 techniques: manual condensation alone (group M, n = 25) or manual condensation with indirect ultrasonic activation (group U, n = 25). MTA was placed incrementally to the level of the root end using the enumerated technique. Samples were weighed immediately before and after filling placement. MTA was removed from all samples so as not to change the root-end preparation, rinsed, and dried. Each sample then underwent MTA placement by the opposite technique, and weight was again measured immediately before and after MTA placement. MTA filling weights for each technique were analyzed statistically using a technique for repeated measures analysis. Statistical analysis was conducted to account for any carryover or order effects. ResultsAfter adjustment for carryover effects, it was found that regardless of the order of placement, the mean fill weight of MTA produced by the indirect ultrasonic method was on average 4.42 mg heavier than that produced by manual condensation alone. This result was statistically significant (P < .0003). ConclusionsUnder simulated root-end surgery conditions, indirect ultrasonic condensation of MTA root-end fillings was shown to produce a filling that was significantly denser than MTA placed by manual condensation alone.

Resorption Treatment Using MTA with Indirect Ultrasonic Activation: Three Case reports

Resorption Treatment Using MTA with Indirect Ultrasonic Activation: Three Case reports

Effect of Varying Water-to-Powder Ratios and Ultrasonic Placement on the Compressive Strength of Mineral Trioxide Aggregate

IntroductionThe purpose of this study was to compare the compressive strength of mineral trioxide aggregate (MTA) when mixed with 2 different water-to-powder (WP) proportions using either hand or ultrasonic placement. MethodsTooth-colored ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and white MTA Angelus (Angelus Soluçoes Odontologicas, Londrina, Brazil) were investigated. One gram of each MTA powder was mixed with either 0.34 or 0.40 g distilled water. The 4 groups were further divided into 2 groups of 5 specimens for each of the following techniques: conventional (ie, hand placement) and placement using indirect ultrasonic activation for 30 seconds. All specimens were subjected to compressive strength testing after 4 days. The results were statistically analyzed with multivariate analysis of variance and Tukey Honestly Significant Difference tests at a significance level of P < .05. ResultsThe mean compressive strength values of ProRoot MTA (84.17 ± 22.68) were significantly greater than those of MTA Angelus (47.71 ± 14.29) (P < .01). Specimens mixed with the 0.34 WP ratio had higher compressive strength values (72.85 ± 25.77) than those mixed with the 0.40 WP ratio (56.69 ± 24.85) (P < .05). The highest compressive strength values were recorded for ProRoot MTA specimens that were mixed in the 0.34 WP ratio, and then the samples were placed with ultrasonic activation (mean = 91.35 MPa). The lowest values were recorded for MTA Angelus samples that were mixed in the 0.40 WP ratio, and the specimens were placed without ultrasonic activation (mean = 36.36 MPa). Ultrasonic activation had no significant difference in terms of compressive strength. ConclusionsWhen using ProRoot MTA and MTA Angelus, higher WP ratios resulted in lower compressive strength values. Ultrasonication had no significant effect on the compressive strength of the material regardless of the WP ratio that was used. Therefore, adherence to the manufacturer's recommended WP ratio when preparing MTA for use in dental applications is advised.

A gas adsorption porosimetry analysis of Portland cement prepared by compaction vs. compaction with indirect ultrasonic agitation

Background: Mineral trioxide aggregate (MTA), is commonly used in endodontic and restorative procedures. Objective: Our objective was to introduce gas adsorption porosimetry as a viable method for evaluation of general porosity and specific pore characteristics of set Portland cement used in substitute for MTA, to investigate the effect of two different obturation methods (compaction and compaction in conjunction with indirect ultrasonic agitation of the cement paste), and to evaluate the correlation between the specific pore characteristics to compressive strength in general. Material and Methods: Portland cement samples were prepared and divided into two groups based on compaction techniques. An initial stereomicroscopic evaluation was done to assess any differences in appearance of pores randomly selected from either of the two experimental groups. Specific pore characteristics and compressive strength were quantified by a gas adsorption porosimeter and an Instron universal testing machine. A two tailed student t-test was used for statistical comparison of data, and a regression analysis was done to evaluate the correlation between each specific pore characteristic and compressive strength in general. Results: The gas porosimetry method provided measurable values relating to specific pore characteristics of Portland cement. The stereomicroscopy evaluation revealed marked differences between samples from the two groups, namely visibly larger pores both on the outside surface and in cross-sections of specimens prepared by the indirect ultrasonic activation method. Conclusions: Gas adsorption porosimetry is a feasible method for evaluation of specific pore characteristics of Portland cement and potentially other dental materials as well.

Effect of ultrasonication on physical properties of mineral trioxide aggregate.

Aim. To evaluate the effect on physical properties of Mineral Trioxide Aggregate (MTA) of using direct hand compaction during placement and when using hand compaction with indirect ultrasonic activation with different application times. Methods. One hundred acrylic canals were obturated in 3 increments with MTA in sample sizes of 10. One group was obturated by hand with an endodontic plugger and the remainder obturated with indirect ultrasonic application, with times ranging from 2 seconds to 18 seconds per increment. Microhardness values, dye penetration depths, and radiographs of the samples were evaluated. Results. As ultrasonic application time per increment increased, microhardness values fell significantly (P < 0.001) while dye penetration values increased (P < 0.001). Microhardness of MTA ultrasonicated for 2 seconds was significantly higher than hand compaction (P = 0.03). Most radiographic voids were visible in the hand-compacted group (P < 0.001), which also had higher dye penetration depths than the 2-second ultrasonicated samples. Ultrasonication of MTA for 10–18 seconds resulted in significantly more voids than 2–8 seconds of ultrasonication (P = 0.02). Conclusion. The use of ultrasonics with MTA improved the compaction and flow of MTA, but excessive ultrasonication adversely affected MTA properties. A time of 2 seconds of ultrasonication per increment presented the best compromise between microhardness values, dye penetration depths, and lack of radiographic voids.

Effect of Various Mixing and Placement Techniques on the Flexural Strength and Porosity of Mineral Trioxide Aggregate

IntroductionThe aim of this study was to evaluate the effect of mechanical and manual mixing as well as the effect of ultrasonic agitation during placement on the flexural strength and porosity of mineral trioxide aggregate (MTA). MethodsWhite ProRoot MTA and white MTA Angelus were used. One gram of each powder was mixed with a 0.34-g aliquot of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 seconds at 4500 rpm or by a saturation technique and application of a condensation pressure of 3.22 MPa for 1 minute. The mixed slurries of all materials were loaded into 2 × 2 × 25 mm molds for testing flexural strength and 3 × 4 mm molds for evaluation of porosity. Half of the specimens were placed in the stainless steel molds by using indirect ultrasonic activation. All specimens were incubated for 4 days. Micro–computed tomography was used to determine the porosity of each specimen, and a 3-point bending test was used to evaluate flexural strength. Tukey honestly significant difference and independent t tests were carried out to compare the means at a significance level of P < .05. ResultsIrrespective of mixing and placement techniques applied, the flexural strength values of ProRoot MTA were significantly greater than those of MTA Angelus (P < .05). A medium negative correlation was found between flexural strength values and total porosity percentage. ConclusionsAlthough mechanical mixing of encapsulated cements was quicker and provided more consistent mixes, this technique along with ultrasonic agitation was not associated with a significant advantage in terms of flexural strength and total porosity over manual mixing.

The Effect of Various Mixing and Placement Techniques on the Compressive Strength of Mineral Trioxide Aggregate

IntroductionThe aim of this study was to evaluate the effect of various mixing techniques including mechanical and manual mixing as well as the effect of ultrasonic agitation during placement on the compressive strength of mineral trioxide aggregate (MTA). MethodsTooth-colored ProRoot MTA (Dentsply Maillefer, Ballaigues, Switzerland) and white MTA Angelus (Angelus Soluções Odontologicas, Londrina, Brazil) were used. One gram of each powder was mixed with a 0.34-g aliquot of distilled water. Specimens were mixed either by mechanical mixing of capsules for 30 seconds at 4,500 rpm or by a saturation technique and the application of a condensation pressure of 3.22 MPa for 1 minute. Half of the specimens were placed in stainless steel molds and agitated using indirect ultrasonic activation. All specimens were subjected to compressive strength testing after 4 days. ResultsThe compressive strength values of ProRoot MTA were significantly greater than those of MTA Angelus (P < .05). The highest compressive strength values were recorded from ProRoot MTA samples that were mixed mechanically and placed using ultrasonic activation (mean = 101.71 MPa), whereas the lowest values were recorded for MTA Angelus samples that were mixed manually and placed without ultrasonic activation (mean = 53.47 MPa). Ultrasonically agitated groups had higher compressive strength values (P < .001). The specimens mixed mechanically had higher compressive strength values than those mixed manually (P < .05). ConclusionsThe compressive strength values of ProRoot MTA were significantly greater than those of MTA Angelus. Mechanical mixing enhanced the compressive strength of the material. Regardless of the mixing techniques applied, ultrasonic agitation improved the compressive strength of the material.

Influence of smear layer removal and application mode of MTA on the marginal adaptation in immature teeth: a SEM analysis

This study was an ex vivo evaluation of the marginal adaptation of mineral trioxide aggregate as an apical barrier using teeth with an open apex and scanning electron microscopy. Eighteen single-rooted human teeth were used. An artificial open apex was created using Gates Glidden drills #6-1 in a crown-down manner until the #1 bur passed through the foramen. A 1.36-mm divergent open apex was created at the foramen by retrograde apical transportation using a #40 Profile 0.6 taper instrument inserted to the length of the cutting blade. The teeth were divided into four groups (n=4), and two teeth served as controls. The GI=mineral trioxide aggregate (MTA) was placed as a 5-mm-thick apical barrier without removal of the smear layer; GII=MTA was placed with indirect ultrasonic activation; GIII=apical plug was placed after removal of the smear layer without indirect ultrasonic activation; and GIV = MTA was placed with indirect ultrasonic activation, but the smear layer had been previously removed. The root apices were visualized with SEM (1000×), and 12 predetermined material/dentine interface points were measured (gaps). One-way anova and Bonferroni's post hoc tests were used to compare the linear measurements of the gaps between the groups. GIV had the lowest gap when compared with other groups, and no statistical differences were found among GI, GII, and GIII. The technique of MTA placement using passive ultrasonic vibration in association with smear layer removal improved the marginal adaptation of the material.

A Micro–Computed Tomography Evaluation of Mineral Trioxide Aggregate Root Canal Fillings

IntroductionThe aim of this study was to assess the effect of indirect ultrasonic activation on the incidence of voids within mineral trioxide aggregate (MTA) root canal fillings and at their interface with the canal walls by using a nondestructive 3-dimensional (3D) micro–computed tomography (micro-CT) analysis. MethodsExtracted human teeth with single canals and minimal curvatures were decoronated, instrumented to size 50/05 apically, and randomly allocated into 4 groups (n = 12). MTA was compacted manually by using hand pluggers in group A (MC). Indirect ultrasonic activation was applied to each increment of manually compacted MTA for 1 second in group B (1 sec-UC), 5 seconds in group C (5 sec-UC), and 10 seconds in group D (10 sec-UC). Filled roots were scanned with a micro-CT device, and 3D analysis of void incidence was carried out by using the SkyScan software. ResultsStatistical analysis showed a significantly lower incidence of voids (P < .05) in the manual compaction (MC) group (0.7%) compared with the ultrasonic activation for 1 second (3.8%), 5 seconds (1.7%), and 10 seconds (1.6%) groups. ConclusionsManual compaction produced significantly denser root fillings than those achieved with ultrasonic activation.

A Quantitative Comparison of the Fill Density of MTA Produced by Two Placement Techniques

This study compared the fill density of mineral trioxide aggregate (MTA) produced by hand condensation with that produced by hand condensation with indirect ultrasonic (US) activation. Sixty acrylic blocks with straight or curved canals were instrumented to an apical size 45, and weighed with a digital electronic balance. In 30 randomly chosen specimens, the canal was filled with MTA by hand condensation and weighed. The MTA was removed; the canal was rinsed and dried, and refilled using hand condensation with indirect US activation. In the other 30 specimens, the procedure was carried out identically but in reverse order. The blocks were then reweighed. The weight of the MTA fill produced by the two placement methods in the two canal configurations was analyzed by a two-way ANOVA. Hand condensation with indirect US activation resulted in an MTA fill that was statistically significantly heavier, and thus denser, than that accomplished by hand condensation alone in both curved and straight canals (p < 0.0001).