Ex vivo shaping ability of reciprocating instruments operated by new users: Reciproc versus WaveOne.

OBJECTIVES: To compare two reciprocating NiTi systems operated by novices for use in curved root canals. METHODS: Fifty mesial roots of extracted mandibular first molars, with 2-2 canal configuration, were scanned with micro-CT and divided into 2 groups according to canal length and curvature: Reciproc and WaveOne. Each system was used to prepare one of the two canals by fourth-year dental students, who were new to reciprocating files and were blinded to the system being used. After another scanning, the pre- and post-instrumentation images were compared 3-dimensionally in software. RESULTS: Some 43 to 46% of the canal wall area remained un-instrumented. Significantly higher proportions of canals were transported towards the isthmus or furcation aspect than the mesial or external aspect. Mean transported distance was the greatest in the coronal one-third. Remaining dentine wall was the thinnest at the furcal aspect near the middle root region. No significant difference was noted between the two brands in the parameters examined. CONCLUSIONS: Both brands of reciprocating file left similar amounts of un-instrumented canal wall, and resulted in similar extent of canal transportation. CLINICAL RELEVANCE: NiTi reciprocating files can safely be used by new users to prepare curved root canals into a predictable shape.

Effectiveness of irrigation strategies on the removal of the smear layer from root canal dentin.

The aim of this study was to evaluate the removal of the smear layer by some commonly used (needle-and-syringe irrigation, sonic activation, ultrasonically activated irrigation) and new root canal irrigation strategies (negative pressure irrigation and polymer rotary file) using a novel approach by comparing pre- and post-experimental images. Prepared root canals (n = 50) were subjected to a split tooth model and divided into 5 groups (n = 10): (1) needle-and-syringe irrigation (control); (2) sonic activation (SA); (3) negative pressure irrigation with continuous warm activated irrigation and evacuation (CWA); (4) polymer finishing file (FF); (5) ultrasonically activated irrigation (UAI). Smear layer scores and percentage of open dentinal tubules (%ODT) were evaluated by 2 examiners before and after irrigation procedures, from the middle and apical thirds of the root canal, on scanning electron microscopic images. Data were analysed using Kruskal-Wallis and post hoc tests at P = 0.05. Needle-and-syringe irrigation (control) showed no significant difference (both smear score and %ODT) compared to the pre-experimental value (P > 0.05). All other groups showed lower smear scores and higher %ODT, compared to the control (P < 0.05). The lowest smear score and highest %ODT were observed in the CWA group, which was significantly different from all other groups (P < 0.05). SA group showed significantly higher smear scores and lower %ODT than FF or UAI (P < 0.05). CWA showed superior removal of smear layer in the middle and apical thirds of the root canal compared to the other irrigation strategies.

Storage media enhance osteoclastogenic potential of human periodontal ligament cells via RANKL-independent signaling.

BACKGROUND: Hank's balanced salt solution (HBSS) and milk have gained wide acceptance as storage media for avulsed tooth. However, the effect of the media and storage time on the periodontal ligament (PDL) cells involvement in the development of root resorption is still unclear. The purpose of this study was to evaluate whether precultured PDL cells in HBSS, milk, or modified Eagle's medium alpha (α-MEM) would affect osteoclastogenesis. MATERIALS AND METHODS: PDL cells were precultured in HBSS, milk, or α-MEM for 1 h or 6 h before being co-cultured with RAW 264.7 cells for an additional 3 days for mRNA analysis and 11 days for osteoclastogenesis assay. RESULTS: Cyclooxygenase-2 (COX-2) mRNA was detected immediately in PDL cells precultured in the three storage media. The expression was up-regulated markedly in all co-cultures when compared with RAW cells alone. As a result of the co-culture, interleukin-1ß (IL-1ß) expression was detectable in both PDL and RAW cells. TRAP+ multinucleated, osteoclast-like cells developed in all co-cultures; the number of TRAP+ cells was highest (P < 0.05) in the co-cultures that PDL cells precultured in milk for 6 h. The mRNA level of receptor activator of nuclear factor-kappa B ligand (RANKL) was not detected in PDL cells. Osteoprotegerin (OPG) mRNA expression reduced with increased preculture time, but the difference was not significant (P > 0.05). CONCLUSIONS: PDL cells kept in the three storage media led to TRAP+ multinucleated, osteoclast-like cells formation via RANKL-independent signaling. The ability to induce osteoclastogenesis may be considered as one of the factors to evaluate the ability of storage medium to maintain PDL viability after tooth avulsion.

Effect of Passive Ultrasonic Irrigation, Er,Cr:YSGG Laser, and Photon-Induced Photoacoustic Streaming against Enterococcus faecalis Biofilms in the Apical Third of Root Canals.

PURPOSE: This study aimed to compare the antibacterial effectiveness of passive ultrasonic irrigation (PUI), Er,Cr:YSGG laser (WTL), and photon-induced photoacoustic streaming (PIPS) using an Er:YAG laser against Enterococcus faecalis biofilms in the apical third of root canals. METHODS: Root canals of 70 single-rooted human teeth were instrumented and infected with E. faecalis for 3 weeks to form biofilms. The samples were randomly divided into five groups as follows: (i) PUI + 3% NaOCl (n = 16); (ii) Er,Cr:YSGG laser (n = 16); (iii) PIPS + 3% NaOCl (n = 16); (iv) positive control group (n = 10); and (v) negative control group (n = 10). The bacterial content in the root canal was sampled using (a) the paper-point sampling method before (S1) and after (S2) treatment and (b) pulverising the apical 5 mm of the root. The number of bacteria recovered from each group was counted as colony-forming units (CFUs). The amount of reduction between the groups was compared with the Kruskal-Wallis test and post-test Dunn's multiple comparisons tests. The significance level was set at 5% (p < 0.05). RESULTS: The samples from the paper-point sampling method showed that the amount of bacteria before (S1) and after treatment (S2) was significantly different between PIPS and WTL, as well as between the PUI and WTL groups. In contrast, no significant difference was found between the PIPS and PUI groups. From the pulverised samples, the results indicated no significant difference among all experimental groups in the amount of bacterial reduction in the apical 5 mm of the root. CONCLUSIONS: PUI and PIPS showed a significantly greater reduction in bacterial content within the main root canal compared with the WTL. There was no difference among all experimental groups in the apical third of the root.

Evaluation of fiber post-supported restorations under simulated occlusal loading.

STATEMENT OF PROBLEM: There is a lack of information comparing the effect of a rigid versus flexible post on the marginal seal of post-and-core supported crowns subjected to long-term repeated loading. PURPOSE: The purpose of this study was to examine the leakage pattern of complete coverage restorations retained with either a metal or fiber-reinforced resin post under simulated occlusal loads. MATERIAL AND METHODS: Thirty-six maxillary central incisors were endodontically treated and provided with a post-and-core supported crown. One group was restored with a fiber-post (EasyPost Lux) and another was restored with a metal post (Parapost) (n=12). Both groups were loaded for 120,000 cycles to 70 N while immersed in a dye solution. A control group (n=12), similarly restored with a fiber post but not loaded, was also included. All teeth were transversely sectioned serially from the tooth-core interface towards the apex. Digital photographs were made to determine the extent of leakage on the buccal, mesial, palatal, and distal aspects along the depth of the post. A nonparametric Kruskal-Wallis test was used to determine any difference between groups (α=.05). RESULTS: Dye penetration occurred in all stress-cycled specimens and was more extensive on the palatal than other aspects. The fiber-post group cyclically stressed to 70 N showed a significantly greater amount of leakage than the control or the Parapost group (P<.05). CONCLUSIONS: In in vitro testing, the rigidity of the post influenced the seal of post-and-core-supported crowns at the palatal margin.

Transition metals and Enterococcus faecalis: Homeostasis, virulence and perspectives.

Enterococcus faecalis, a Gram-positive bacterium, is known to be a key player in several chronic infections as well as nosocomial, heart valve, urinary tract, surgical wound, and dental root canal infections. The capability to sense different transition metal levels and tune its response accordingly endows it with the potential to thrive and cause infections in several host niches. Over the past decade, our knowledge of how transition metals play a critical role in maintaining homeostasis of E. faecalis has improved significantly. The aim of this review is to elucidate the roles of metals such as iron, manganese, zinc, and copper in the physiology, metabolism, and pathogenicity of E. faecalis. These essential micronutrients contribute to energy production, redox stress response, expression of virulence determinants, and cooperation in polymicrobial communities. The review also highlights metal homeostasis systems in E. faecalis, which respond to fluctuations in extracellular metal levels, and regulate the intracellular metal content. Regulation of intracellular metallome secures the tolerance of E. faecalis to oxidative stress and host-mediated metal sequestration strategies. Therapeutic interventions which deprive E. faecalis of its essential metal requirements or disrupt its homeostatic control have been proposed to combat E. faecalis infections.

Debris extrusion during root canal preparation with nickel-titanium instruments using liquid and gel formulations of sodium hypochlorite in vitro.

This study compared the amount of apically extruded debris during root canal preparation with three single-file systems using liquid and gel-based formulations of sodium hypochlorite (NaOCl) or distilled water. Seventy-two single-canalled roots were divided into three groups: HyFlex EDM (Coltene-Whaledent); Reciproc Blue (VDW); and F-One Blue (Shanghai Fanta) and then divided into three subgroups: NaOCl liquid (Imicrly), NaOCl gel (Cerkamed Medical) and distilled water. The amount of extruded debris was calculated by determining the dry weight of the debris collected. Data were analysed using Kruskal-Wallis test with Bonferroni correction. Debris extrusion occurred in all subgroups. Both the instrument and the irrigant had an impact. The F-One Blue tended to extrude the least debris, though no significant difference was observed in the pairwise comparisons between instruments. NaOCl liquid resulted in significantly more extruded debris than NaOCl gel or distilled water. The results lead us to conclude that the NaOCl gel reduced debris extrusion compared to NaOCl liquid.

Spatial Cleaning Action of Ultrasonic Irrigation on Enterococcus faecalis Biofilm.

This study aimed to examine the spatial cleaning effect of ultrasonic irrigation in simulated root canal with oblong cross section in the absence of antimicrobial agent. A 7-day E. faecalis biofilm was cultivated in a rectangular, simulated canal model and subjected to passive ultrasonic irrigation (PUI) with sterile saline for 5 minutes. After that, the biofilm was examined by confocal microscopy after bacterial viability staining at 58 sites around and beyond the endosonic file. Results showed that, at the vicinity of the file, the amount of viable bacteria ranged from 13.1% (2.75 mm from the tip) to 40.5% (4.5 mm level). Lesser amounts of live bacteria were observed within 1 mm from the vibrating file, which amount increased for sites farther away. At 3 mm distance, the amount of bacteria (35.5 to 64.4%) was significantly greater than areas situated close to the vibrating file (P < 0.01). Sites next to the anti-nodes of file had less bacteria remaining than sites near the nodes (P = 0.050). Apically (0.5 mm or more), the amount of bacteria was significantly greater than that at the file tip (16.4%) (P < 0.05). It was concluded that PUI is able to dislodge a single-species biofilm, provided that they are situated in close vicinity to the vibrating file.

Low-cycle fatigue of rotary NiTi endodontic instruments in hypochlorite solution.

OBJECTIVE: To examine the low-cycle fatigue (LCF) behaviour of NiTi rotary endodontic instruments in aqueous sodium hypochlorite solution. METHODS: Four brands of NiTi rotary instrument (n=179) were subjected to a rotational-bending fatigue test at a rate of 250rpm until fracture, the instrument being immersed in 1.2% sodium hypochlorite solution. The surface strain amplitude, calculated from the curvature (from a pre-test photograph) and diameter of the fracture cross-section (from SEM photomicrograph) was plotted against the total number of revolutions to failure. An apparent fatigue-ductility exponent was determined from a regression line fitted to the LCF lives for each brand of instrument. All detached fragments were examined fractographically for crack initiation and the extent of crack extension into the cross-section. The values were compared using one-way analysis of variance (ANOVA) or chi2, where appropriate, at alpha=0.05. RESULTS: A linear strain-life relationship was obtained for all groups; the apparent fatigue-ductility exponent was similar between various brands (ANOVA, P>0.05), but not for the number of crack origins (chi2, P<0.05). There was an inverse, linear relationship between the square root of the extension of the fatigue-crack and the strain amplitude. SIGNIFICANCE: NiTi rotary instruments fatigued in hypochlorite shows a strain-life relationship with low-cycle and high-cycle fatigue regions. The LCF behaviour is not affected by the cross-sectional shape of the instrument. There appears to be a critical extent of crack propagation for various surface strain amplitudes leading to final, catastrophic fracture of the instrument.

Periodontal Blood Flow Protects the Alveolar Bone from Thermal Injury during Thermoplasticized Obturation: A Finite Element Analysis Study.

INTRODUCTION: The purpose of this study was to investigate the heat transfer during thermoplastic obturation and the cooling capacity of blood flow in the periodontal ligament (PDL) using finite element analysis (FEA). METHODS: A 3-dimensional digital tooth model was constructed based on micro-computed tomographic scanning of a mandibular first molar after chemomechanical preparation in vitro. A layer of PDL with or without simulated blood flow was built on the root portion of the tooth in software. Two heat-assisted obturation techniques (ie, the single-wave condensation technique and the warm vertical compaction technique followed by backfilling with injectable gutta-percha) were examined using an FEA package. RESULTS: In the model without blood flow, the highest temperature at the alveolar bony aspect of the PDL was 50.0°C along the distal canal and 52.5°C for the mesiolingual canal when the single-wave technique was used. With the warm vertical compaction technique, the highest temperature was 47.3°C for the distal canal and 47.8°C for the mesiolingual canal. In the model with simulated periodontal blood flow, a notable drop in the peak temperatures at the root surface and at the adjoining alveolar bone was observed for both the distal and mesiolingual canals; all peak temperatures at the PDL fell below 47°C regardless of the obturation techniques used. The greatest rise in temperature was situated at the furcation aspect of the middle third of both roots. CONCLUSIONS: The cooling capacity of blood flow in the PDL is a factor that must be considered in the investigation of heat transfer during thermoplastic obturation.

Low-cost, flexible, disinfectant-free and regular-array three-dimensional nanopyramid antibacterial films for clinical applications.

In this work, a low-cost, scalable and highly repeatable approach was developed to prepare polystyrene films with three-dimensional nanopyramids on the surface. The nanopyramids have a tunable aspect ratio and more importantly, their anti-bacterial performance has been systematically studied. The effectiveness of the nanopyramids on E. coli growth inhibition and the role of the nanostructure aspect ratio were carefully studied through scanning electron microscopy and confocal laser scanning microscopy. The results showed an excellent antibacterial performance with more than 90% reduction in the E. coli population in all nanopyramid samples after a 168 h prolonged incubation time. The nanopyramid film developed here can be used for clinical and commercial applications to prevent the growth of pathogenic bacteria on various surfaces.

Effect of environment on low-cycle fatigue of a nickel-titanium instrument.

This study examined the low-cycle fatigue (LCF) behavior of a nickel-titanium (NiTi) engine-file under various environmental conditions. One brand of NiTi instrument was subjected to rotational-bending fatigue in air, deionized water, sodium hypochlorite, or silicone oil. The curvature of each instrument, diameter of the fracture cross-section, and the number of rotations to failure were determined. The strain-life relationship in the LCF region was examined by using one-way analysis of variance, and the number of crack origins with chi2, for differences between groups. The results showed a linear relationship, on logarithmic scales, between the LCF life and the surface strain amplitude; regression line slopes were significantly different between noncorrosive (air, silicone oil) and corrosive (water, hypochlorite) environments (P < .05), as well as number of crack origins (P < .05). Hypochlorite was more detrimental to fatigue life than water. In conclusion, environmental conditions significantly affect the LCF behavior of NiTi rotary instruments. Fatigue testing of NiTi engine-files should be in a service-like environment.

Does electropolishing improve the low-cycle fatigue behavior of a nickel-titanium rotary instrument in hypochlorite?

The purpose of this study was to compare the low-cycle fatigue (LCF) behavior of electropolished and nonelectropolished nickel-titanium (NiTi) instruments of the same design in hypochlorite. Forty-five electropolished and 62 nonelectropolished NiTi engine files were subjected to rotational bending at various curvatures in 1.2% hypochlorite solution. Number of revolutions to failure, crack-initiation sites, extent of slow crack extension into the fracture cross-section, and surface-strain amplitude were noted. A linear relationship was found between LCF life and surface-strain amplitude for both groups, with no discernible difference between the two (p > 0.05). No electropolished instrument showed more than one crack origin, significantly fewer than for the nonelectropolished instruments (p < 0.05). The square root of crack extension and strain amplitude were inversely related. Although surface smoothness is enhanced by electropolishing, this did not protect the instrument from LCF failure.

Identification of C-shaped canal in mandibular second molars. Part I: radiographic and anatomical features revealed by intraradicular contrast medium.

The purpose of this study was to investigate radiographic features of the C-shaped canal system in mandibular second molars and their relationship to the canal anatomy by using intraradicular contrast medium and micro-computed tomography (microCT) scanning. Thirty mandibular second molars with fused roots were collected and stored in 10% formalin solution. After being scanned by microCT and reconstructed with 3-dimensional software, the pulp tissue of each tooth was removed mechanically and chemically. The contrast medium was introduced into the canal by using a specialized device, and the buccal-lingual radiograph was taken for each tooth. The radiographic images were classified into 3 types: Types I (merging type), II (symmetrical type), and III (asymmetrical type). The relationship between the radiographic and anatomic features was analyzed by collating the microCT scanned canal images with the radiographic types. The results were subject to Kruskal-Wallis test. Findings showed that 10 teeth were Type I, 10 teeth Type II, and 10 teeth Type III. Types I and III had more C1, C2 canal shape in their canal orifice, coronal, and middle canal portion than the Type II (P < .05). Types II and III had more C3a, C3b canal shapes in the apical canal portion than Type I (P < .05). On the basis of these results, the radiographic features revealed by the intraradicular contrast medium can help to identify the canal anatomy of C-shaped canal system in mandibular second molars.

Study of the progressive changes in canal shape after using different instruments by hand in simulated S-shaped canals.

This study analyzed the progressive changes in canal shape after the use of different instruments by hand in simulated S-shaped canals. Forty simulated canals with double curvatures, 30 degrees coronally and 20 degrees apically, were randomly divided into four groups and prepared with stainless steel K-files, the ProTaper for hand use (PHU) system, NiTi K-files, and the combination of PHU and NiTi K-files, respectively, by hand. All canals were scanned pre-and postoperatively. Each postinstrumentation image was superimposed with the preoperative one in a computer. The amount of material removed after every instrument was measured at 14 points. Statistical analysis was performed using an analysis of variance (ANOVA) test at alpha=0.05. All four instruments straightened the S-shaped canals, except the combination of PHU (S1, Sx, and S2) and NiTi K-files, which created a continuous funnel shape. There was a significant difference in the amount of material removed between S2 and F1 of the PHU system (p<0.05), and the finishing files of PHU created the same transportation as the stainless steel instruments with the same tip size (p>0.05).

C-shaped canal system in mandibular second molars Part III: The morphology of the pulp chamber floor.

The purpose of this study was to investigate the morphology of pulp chamber floors in mandibular second molars with a C-shaped canal system. Forty-four extracted mandibular second molars with C-shaped roots were collected from a native Chinese population. After the teeth were scanned by the micro-computed tomography (microCT), the pulp chamber floors were reconstructed three-dimensionally using three-dimensional software. The reconstructed images were classified into four types based on the shape of the pulp chamber floor and the location of the dentin fusion between the peninsular-like floor and the pulp chamber wall. Of the 44 reconstructed pulpal floors, 38 (86.37%) were C-shaped (peninsula-like floor) in which 8 (18.18%) had a continuous C-shaped orifice (type I); 16 (36.37%) had a dentin fusion between the peninsula-like floor and buccal pulp chamber wall, forming one or two mesial orifice(s) and a distal orifice (type II); and 14 (31.82%) had a dentin fusion between the peninsula-like floor and the mesial pulp chamber wall, forming a large mesiobuccal-distal (MB-D) orifice and a small mesiolingual orifice (type III). Six (13.63%) teeth did not have a C-shaped floor configuration (type IV). The number and configuration of the canals at different levels below the orifices were analyzed. The results suggested that most teeth in this study with C-shaped roots also have a C-shaped pulpal floor and that a new classification of pulpal floor anatomy would be helpful in locating the C-shaped canals.

C-shaped canal system in mandibular second molars part IV: 3-D morphological analysis and transverse measurement.

The purpose of this study was to investigate three-dimensional (3-D) morphology of C-shaped root canal system using micro-computed tomography (microCT) and 3-D reconstruction. There were 102 extracted mandibular second molars with fused roots collected from a native Chinese population. The teeth were scanned by microCT and reconstructed by 3-D software. The 98 teeth that possessed a C-shaped canal system were further analyzed. The 3-D reconstructed images of canals were classified into three categories: merging type (type I), symmetrical type (type II), and asymmetrical type (type III). The cross-sectional images of each tooth were submitted to computer analysis, and the minimum canal wall thickness was measured. In these 98 molars, 32 (32.65%) teeth showed a merging type appearance, 38 (38.78%) a symmetrical type and 28 (28.57%) an asymmetrical type. The minimum canal wall thickness in type I was thicker than that in type II or type III in the apical and middle portion (p < 0.05). Being fully aware of the configuration of C-shaped root canal system and the location of minimum wall thickness will ensure more efficient root canal treatment.

Mathematical modeling of flexural behavior of rotary nickel-titanium endodontic instruments.

The aim of the present study was to establish a mathematical model to characterize the flexural behavior of nickel-titanium (NiTi) rotary instruments. The bending behavior of ProFile (0.06 and 0.04 tapers), K-3 (0.06 taper), Quantec (0.04 taper) with tip size of ISO 25, was assessed by pressing the tip of the static rotary file against a smooth, freely movable, glass surface. The deflected instrument was photographed digitally, and the deflection path was digitized in software, to which data a function was fitted that best described the bending behavior of the instrument. It was found that all instruments deflected in a manner closely resembling a negative exponential function: y = A x e(-x/b). The present approach indicated that the analytical difficulties of handling the complex cross-section in tapering spirals in beam-bending theory may be circumvented by a practical and elementary curve-fitting method.

Incidence and factors associated with endodontic inter-appointment emergency in a dental teaching hospital in China.

OBJECTIVE: To assess the incidence of endodontic inter-appointment emergency (EIE) in a dental teaching hospital in China, and to correlate its occurrence with preoperative and treatment parameters. METHODS: Three thousand six hundred and ninety six cases were collected at root canal treatment appointments on demographics, presenting symptoms, treatment procedures and periradicular status. The operators consisted of faculty, undergraduate students and advanced trainees. Root canals were conventionally instrumented and then medicated. No systemic medication was prescribed. In cases EIE developed between appointments, an emergency visit was arranged and active treatment was carried out. The data of EIE cases were statistically analyzed using the chi-square test and a multiple logistic regression model. RESULTS: The overall incidence of EIE was 5%, which rate was 5.5% in females and 4.3% in males. Analyses of the potential factors revealed that patient age, tooth location, preoperative percussion pain and pulp status were the most important independent variables. CONCLUSION: EIE was significantly associated with some host factors (patient age, tooth location) and presenting factors (preoperative percussion pain, pulp status).

Cleaning effectiveness and shaping ability of rotary ProTaper compared with rotary GT and manual K-Flexofile.

PURPOSE: To compare the cleaning efficacy and shaping ability of engine-driven ProTaper and GT files, and manual preparation using K-Flexofile instruments in curved root canals of extracted human teeth. METHODS: 45 canals of maxillary and mandibular molars with curvatures between 25 degrees and 40 degrees were divided into three groups. The groups were balanced with regard to the angle and the radius of canal curvature. Canals in each group were prepared to an apical size of 25 with either the rotary ProTaper or GT system, or manually with K-Flexofile using the modified double-flared technique. Irrigation was done with 2 mL 2.5% NaOCl after each instrument and, as the final rinse, 10 mL 2.5% NaOCl then 10 mL 17% EDTA and finally 5 mL distilled water. The double-exposure radiographic technique was used to examine for the presence of apical transportation. The time required to complete the preparation, as well as any change in working length after preparation were recorded. The roots were then grooved and split longitudinally. The amounts of debris and smear layer were evaluated at the apical, middle and coronal regions under the scanning electron microscope. Data were analyzed either parametrically with the F-test or non-parametrically using the Kruskal-Wallis test, where appropriate. RESULTS: Two GT files but none of the K-Flexofile and ProTaper instruments separated. For debris removal, the ProTaper group achieved a better result than GT (P < 0.05) but not the K-Flexofile group at all three regions (apical, middle and coronal). K-Flexofiles produced significantly less smear layer than ProTaper and GT files only in the middle third of the canal (P < 0.01). Both NiTi rotary instruments maintained the original canal shape better than the K-Flexofiles (P < 0.05) and required significantly less time to complete the preparation.