A Micro–computed Tomography Evaluation of the Shaping Ability of Two Nickel-titanium Instruments, HyFlex EDM and ProTaper Next

Evaluation of Mechanical Versus Manual Root Canal Preparation in Primary Molars-A Comparative In Vitro Study

The endodontic treatment of primary teeth is to maintain the function of the tooth free of symptoms until its physiological exfoliation. A critical factor for success is how quickly and effectively the root canal preparation can be performed. Therefore, the aim of this comparative in vitro study was to analyze the efficiency of two mechanical root canal preparation systems FM (FlexMaster) and HF (HyFlex EDM) to manual KF (K-file) on extracted primary molars. A total of 45 teeth were divided into three groups (n = 15): KF (#15-35), FM (04#30) and HF (25/~ OneFile). Root canal preparation was performed, and the preparation time was measured. All root canals were non-destructively analyzed by micro-computed tomography in the cervical, middle and apical thirds before and after preparation with regard to the parameters of canal transport (in μm) and centering ratio (0-1). Statistical analysis was performed at a 5% significance level using non-parametric tests. HF caused the lowest canal transport in the apical third (p = 0.008). The centering ratio value of HF was significantly higher in the middle third of the root canals than in the other two groups (p < 0.01). The mean instrumentation time was significantly higher for KF (6.67 min) than for FM (4.69 min) and HF (4.03 min, p < 0.01). HF can be recommended for primary molar root canal treatment.

Diamond-coated ultrasonic tip decreases debris and uninstrumented surface after preparation of curved canals with isthmus

The aim of this study was to evaluate root canal preparation with nickel titanium rotary instruments and complementary preparation with ultrasonic tip in curved canals of mandibular molars with isthmus. Twenty-eight mesial roots of mandibular molars with curvature between 20° and 40° and presence of isthmus throughout the entire extension of the root canals were prepared using ProDesign Logic CM (PDL) up to size 40.05, or HyFlex EDM (HFEDM) up to size 40.04. Complementary preparation was performed in the isthmus region using the ultrasonic insert E18D (Helse, Istmo Diamantada). The root canals were scanned using micro-CT (SkyScan 1176) at 9 µm voxel size before and after each preparation step. Transportation, percentage of increase in volume, debris and uninstrumented surface (UNS) were evaluated. Mann Whitney, Wilcoxon, paired and non-paired t-tests were used for statistical analysis (α = 0.05). The canals prepared with PDL and HFEDM obtained similar results for all the variables assessed before using E18D (p > 0.05). E18D significantly decreased the percentage of debris and UNS values in both Groups (p < 0.05). The complementary preparations with E18D caused a smaller quantity of debris in the isthmus of the canals previously prepared with PDL in comparison with HFEDM (p < 0.05). PDL and HFEDM provided similar root canal preparation. PDL promoted a smaller quantity of Debris in the isthmus than HFEDM after using E18D. E18D significantly improved cleaning, and reduced Debris and UNS.

Shaping ability of BlueShaper, TruNatomy, DC Taper and HyFlex EDM in long oval canals: An ex vivo study

AIM

This study evaluated and compared the shaping ability of four rotary instrument systems in long-oval root canals using microcomputed tomographic (micro-CT) evaluation. Currently, there is no data available on the canal shaping abilities of BlueShaper and DC Taper instruments.

METHODOLOGY

Sixty-four single-rooted mandibular premolars were matched based on similar root canal morphologic features as determined by (micro-CT) and randomly assigned to 1 of 4 experimental groups (n = 16) according to the instrument system used: BlueShaper, TruNatomy, DC Taper and HyFlex EDM One File. Changes in the root canal surface and volume, remaining dentine thickness, and number of prepared areas were assessed.

RESULTS

No significant differences were found amongst the four instrument systems for the parameters evaluated (p > .05). There was a significant reduction in the number of unprepared areas and the remaining dentine thickness after each increase in size of the instruments tested (p < .05).

CONCLUSIONS

The four instrument systems perform similarly in long oval root canals. Although none could prepare all canal walls, larger preparations incorporated significantly more surfaces in the final shape.

Comparative Evaluation of Root Canal Transportation and Centering Ability in Curved Mesiobuccal Canals of Mandibular First Molars after Instrumentation with Different File Systems-An In vitro Study

Aim

To assess the canal transportation and centering ability in the mandibular first molars' curved mesiobuccal canals after instrumentation with file systems XP endo Shaper, self-adjusting File (SAF), Hyflex EDM, Pro Taper NEXT, WaveOne Gold, and K files with the help of Cone-Beam Computed Tomography (CBCT).

Materials and Methods

Ninety recently extracted mandibular first molars with mesiobuccal roots that had a 25-30 degree canal curvature were assessed. Following preoperative CBCT scans, teeth were allocated randomly to six experimental groups of fifteen. After preparation with XP endo Shaper, SAF, Hyflex EDM, Pro Taper Next, WaveOne Gold, and K files, post-instrumentation scans were taken using same parameters as pre operative scans. At 3 mm, 6 mm, and 9 mm from the apex, samples were assessed for canal transportation and centering ratio.

Results

Apical transportation was least for XP endo Shaper as compared to other groups except SAF and the results were statistically significant. K file showed the highest apical transportation toward the lateral wall of the root canal. XP endo Shaper was better in maintaining centering ability of middle and apical third of canal and SAF was better in maintaining centering ability of coronal third.

Conclusion

In root canal preparation, least apical transportation and better centering ability with XP endo Shaper than other file systems compared. K file showed the highest transportation.

Comparative Evaluation of Dentinal Defects After Root Canal Preparation Using Various Nickel Titanium Files: An In Vitro Study

AIM

This study set out to compare the damage done to dentin by three distinct titanium file brands - the Hyflex EDM, the ProTaper Next, and the Waveone Gold Nickel - in order to draw conclusions about which one is the most effective.

MATERIALS AND METHODS

Forty-first premolars in the mandible with straight canals and single roots were instrumented using Hyflex EDM, Waveone Gold, and Protaper Next. Dentinal flaws after endodontic treatment were studied by sectioning specimens using a hard tissue microtome and analyzing them under a stereomicroscope.

RESULTS

There was no discernible variation between the groups in the coronal third (p=0.312) or apical third (p=0.076). Hyflex EDM and Protaper Next differed significantly in the middle portion of the tape (p=0.016). The Hyflex EDM sample had the fewest cracks. There was no statistically significant difference between Hyflex EDM and Waveone Gold; however, Hyflex EDM had fewer fractures in the middle third of the sample than Waveone Gold did.

CONCLUSION

Electric discharge machining (EDM) files made from Hyflex proved to be far superior to their Protaper Next and Waveone Gold counterparts as they induced the fewest cracks in the middle third of the root dentin.

Advancing Nitinol: From heat treatment to surface functionalization for nickel–titanium (NiTi) instruments in endodontics

Nickel-titanium (NiTi) alloy has been extensively researched in endodontics, particularly in cleaning and shaping the root canal system. Research advances have primarily focused on the design, shape, and geometry of the NiTi files as well as metallurgy and mechanical properties. So far, extensive investigations have been made surrounding surface and thermomechanical treatments, however, limited work has been done in the realm of surface functionalization to augment its performance in endodontics. This review summarizes the unique characteristics, current use, and latest developments in thermomechanically treated NiTi endodontic files. It discusses recent improvements in nano-engineering and the possibility of customizing the NiTi file surface for added functionalization. Whilst clinical translation of this technology has yet to be fully realized, future research direction will lie in the use of nanotechnology.

•

Nitinol (Nickel Titanium alloy) is widely used to clean/shape root canal system in endodontics.

•

To enhance its performance, various thermo-mechanical and nano-engineering modifications have been performed.

•

This comprehensive review summarizes the latest advances and future trends relating to functionalized NiTi endodontic files.

Evaluation of design, mechanical properties, and torque/force generation of heat-treated NiTi glide path instruments

BACKGROUND

Recently, various kinds of heat-treated nickel-titanium (NiTi) glide path instruments have been manufactured. This study aimed to investigate design, phase transformation behavior, mechanical properties of TruNatomy Glider (#17/02), V Taper 2H (#14/03), and HyFlex EDM (#15/03) and compare torque/force generated during simulated glide path preparation with them.

METHODS

The designs and phase-transformation behaviors of the instruments were examined via scanning electron microscopy (n = 3) and differential scanning calorimetry (n = 2). Their bending (n = 15), torsional (n = 15), and cyclic fatigue resistances (n = 15) were tested. The ultimate strength and distortion angle were obtained from torsional resistance test. The number of cycles to failure (NCF) was calculated from cyclic fatigue resistance test. The preparation of the glide path was simulated using a double-curved artificial canal (n = 15), and the maximum torque and screw-in forces were measured. Data except NCF was compared between brands with one-way ANOVA with Tukey's honestly significant difference test. NCF was analyzed via Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

TruNatomy Glider had the greatest number of threads. TruNatomy Glider showed progressive taper, while V Taper 2H and HyFlex EDM had constant taper. The austenitic transformation-finish temperatures of all the instruments were above body temperature. V Taper 2H demonstrated significantly lower ultimate strength, higher distortion angle, and a higher number of cycles to failure compared with HyFlex EDM and TruNatomy Glider (p < 0.05). The maximum torque generated during preparing glide path was lowest for V Taper 2H, and the maximum screw-in force was lowest for HyFlex EDM (p < 0.05). TruNatomy Glider generated the highest torque and screw-in force during the apical preparation.

CONCLUSIONS

V Taper 2H #14/03 showed superior cyclic fatigue resistance and lower ultimate strength. TruNatomy Glider generated greater clockwise torque and screw-in force during apical preparation. The mechanical properties, torque, and screw-force was affected by design of heat-treated glide path instruments. Cervical pre-flaring prior to glide path instrument is recommended.

Root canal length changes during mechanical preparation due to different cervical enlargement patterns

This study aimed to evaluate the root canal real length (RL) changes due to the mechanical instrumentation use with different flaring magnitudes. After access cavity, 60 mesial root canals of mandibular molars were randomly separated in three groups: Hyflex EDM (HF; #25/.12, #10/.05 e #25/~), Reciproc Blue (RB; R25), and MTwo (M2; #10/.04, #15/.05, #20/.06 e #25/.06). The RL was defined as the apical limit, and 2.5% sodium hypochlorite irrigating solution was chosen. After the access cavity (RL 1), cervical flaring (RL 2), and complete chemical-mechanical preparation (RL 3), the RL was evaluated. The RL was evaluated by a blind examiner with the aid of a microscope (16x) placing the endodontic file stop at the coronary reference. When comparing length measurements, the RL was shorter before instrumentation than that after instrumentation. A reduction of 0.65 mm (HF), 0.61 mm (RB), and 0.48 mm (M2) was observed. However, among groups, no statistical differences were found (p > 0.05). Under the conditions tested, it can be inferred that all mechanical systems provoked RL variations, which emphasizes the need for constant verification of the odontometry, mainly before root canal obturation.

A comparative evaluation of remaining dentin thickness following biomechanical preparation of teeth using different rotary file systems: An in vitro study

Aim:

Materials and Methodology:

Statistical Analysis Used:

Results:

Conclusion:

Combination of a new ultrasonic tip with rotary systems for the preparation of flattened root canals

Objectives

This study evaluated 2 nickel-titanium rotary systems and a complementary protocol with an ultrasonic tip and a small-diameter instrument in flattened root canals.

Materials and Methods

Thirty-two human maxillary second premolars with flattened canals (buccolingual diameter ≥4 times larger than the mesiodistal diameter) at 9 mm from the radiographic apex were selected. The root canals were prepared by ProDesign Logic (PDL) 30/0.01 and 30/0.05 or Hyflex EDM (HEDM) 10/0.05 and 25/0.08 (n = 16), followed by application of the Flatsonic ultrasonic tip in the cervical and middle thirds and a PDL 25/0.03 file in the apical third (FPDL). The teeth were scanned using micro-computed tomography before and after the procedures. The percentage of volume increase, debris, and uninstrumented surface area were analyzed using the Kruskal-Wallis, Dunn, Wilcoxon, analysis of variance/Tukey, and paired and unpaired t-tests (α = 0.05).

Results

No significant difference was found in the volume increase and uninstrumented surface area between PDL and HEDM (p > 0.05). PDL had a higher percentage of debris than HEDM in the middle and apical thirds (p < 0.05). The FPDL protocol resulted in less debris and uninstrumented surface area for PDL and HEDM (p < 0.05). This protocol, with HEDM, reduced debris in the middle and apical thirds and uninstrumented surface area in the apical third (p < 0.05).

Conclusions

High percentages of debris and uninstrumented surface area were observed after preparation of flattened root canals. The HEDM, Flatsonic tip, and 25/0.03 instrument protocol enhanced cleaning in flattened root canals.

Microscopic Assessment of Dentinal Defects Induced by ProTaper Universal, ProTaper Gold, and Hyflex Electric Discharge Machining Rotary File Systems - An in vitro Study

Background:

Biomechanical preparation of root canal can damage root dentin leading to the formation of dentinal cracks which can eventually lead to fracture and failure of the treatment.

Aim:

The aim was to investigate the incidence of dentinal defects in root canals prepared with ProTaper Universal, ProTaper Gold, and Hyflex electric discharge machining (EDM) rotary file systems using handheld USB digital microscope.

Materials and Methods:

One hundred and fifty extracted mandibular premolar teeth with single canal were randomly divided into five groups (n = 30). Group 1: unprepared (negative control). Group 2: canal preparation done with nickel–titanium hand files (positive control), Group 3: canals prepared with ProTaper Universal rotary system, Group 4: canal preparation done with ProTaper Gold rotary system, and Group 5: canals prepared with Hyflex EDM rotary system. The specimens were sliced at 3 mm, 6 mm, and 9 mm from the apex with a slow-speed saw under water cooling. Digital images of each section were captured at ×40 magnification with the aid of a microscope. Two independent evaluators assessed the images for the presence of dentinal defects. The number of dentinal defects was recorded and Chi-square test was used for statistical analysis (P < 0.05).

Results:

The number of specimens presenting dentinal defects was as follows: Group 3; ProTaper Universal – 9/30 (30.0%), Group 4; ProTaper Gold – 2/30 (6.7%), and Group 5; Hyflex EDM – 1/30 (3.3%). No defects were detected in the negative and positive control groups (Group 1 and Group 2).

Conclusion:

ProTaper Universal showed the highest percentage of defects in comparison to ProTaper Gold and Hyflex EDM.

Shaping ability of three thermally treated nickel-titanium systems in S-shaped canals

This study aimed to compare the shaping ability of ProTaper Next (PTN), HyFlex EDM (HEDM) and One Curve (OC) systems manufactured via different thermal treatment methods in simulated S-shaped canals. Sixty S-shaped canals in clear resin blocks were enlarged to a final apical size of 25 using PTN, HEDM and OC instruments (n = 20 canals/group). Composite images were obtained by superimposing pre- and post-preparation images. The amount of removed resin was measured perpendicularly to the canal surface in 22 points. Prepared canal width and canal transportation at different levels were determined. Canal aberrations were also recorded. Data were statistically analysed using analysis of variance, the Kruskal-Wallis and the chi-square tests at a 0.05 significance level. OC produced the most conservative enlargement and better maintained particularly the apical curvature of the S-shaped canals than HEDM and PTN. OC and HEDM better maintained the canal terminus and coronal curvature than PTN.

Comparative evaluation of mechanical properties and shaping performance of heat-treated nickel titanium rotary instruments used in the single-length technique

This study aimed to evaluate the mechanical properties of contemporary heat-treated nickel-titanium (NiTi) rotary instruments used in the single-length technique [ProTaper Next (PTN), HyFlex EDM (EDM), and JIZAI (JZ)]. Bending loads, cyclic fatigue resistance, torque/force values and canal-centering ratios were evaluated for the three instruments and a non-heat-treated experimental NiTi instrument with the same geometry as JZ (nJZ). EDM and JZ exhibited significantly lower bending load and more cycles to failure compared with nJZ and PTN (p<0.05). PTN and JZ exhibited significantly better centering ability than nJZ and EDM (p<0.05). JZ and nJZ generated significantly smaller upward force and maximum torque than PTN and EDM (p<0.05). Under the present experimental condition, JZ exhibited flexibility and cyclic fatigue resistance comparable to EDM, better maintained the canal curvature than the other instruments, and generated smaller torque and screw-in force than PTN and EDM.

Shaping and Centering Ability, Cyclic Fatigue Resistance and Fractographic Analysis of Three Thermally Treated NiTi Endodontic Instrument Systems

The better understanding of the clinically important behavioral features of new instrument systems has an important significance for the clinical endodontics. This study aimed to investigate the shaping and centering ability as well as cyclic fatigue resistance of HyFlex CM (CM), HyFlex EDM (EDM) and EdgeFile (EF) thermally treated nickel-titanium (NiTi) endodontic instrument systems. Sixty curved root canals of the mesial roots of mandibular molars were randomly assigned into three groups (n = 20) and shaped using CM, EDM and EF files up to the size 40 and taper 04 of the instruments. µCT scanning of the specimens before and after preparation was performed and the morphometric 2D and 3D parameters were evaluated in the apical, middle and coronal thirds of root canals. In each group, 40.04 instruments (n = 20) were subjected to the cyclic fatigue resistance test in artificial root canals at 37 °C temperature until fractures occurred, and the number of cycles to failure (NCF) was calculated. The fractographic analysis was performed using a scanning electron microscope, evaluating topographic features and surface profiles of the separated instruments. The one-way analysis of variance with post hoc Tuckey's test was used for statistical analysis of the data; the significance level was set at 5%. All systems prepared the comparable percentage of root canal surface with the similar magnitude of canal transportation in all root thirds (p > 0.05), but demonstrated significantly different resistance to cyclic fatigue (p < 0.05). The most resistant to fracture was EF, followed by EDM and CM. The length of the fractured fragments was not significantly different between the groups, and fractographic analysis by SEM detected the typical topographic features of separated thermally treated NiTi instrument surfaces.

Root Canal Preparation and Enlargement Using Thermally Treated Nickel-Titanium Rotary Systems in Curved Canals

INTRODUCTION

The purpose of this study was to evaluate root canal preparation and apical enlargement of curved canals using rotary heat-treated and heat/surface-treated systems by micro-computed tomographic imaging.

METHODS

Curved mesial root canals (n = 48) of mandibular molars (20°-40°) were prepared using ProDesign Logic (PDL; Easy Equipamentos Odontológicos, Belo Horizonte, MG, Brazil) 25/.01 and 25/.06 or HyFlex EDM (HFEDM) 10/.05, HyFlex CM 20/.04, and HFEDM 25/.08. Apical enlargement was performed using PDL 40/.05 or HFEDM 40/.04. Scanning (9 μm) was performed before and after preparation and after apical enlargement using micro-computed tomographic imaging. Volume, percentage of volume increase, debris, untouched root canal surface, and centering ability were analyzed. Statistical analysis was performed using Mann-Whitney, Wilcoxon, and unpaired t tests (α = .05).

RESULTS

HFEDM promoted a higher volume increase of the root canals than PDL after preparation and after apical enlargement (P < .05). The apical enlargement promoted a significant decrease in debris and untouched surface in both groups (P < .05). The percentage of debris and untouched surface were similar between HFEDM and PDL after preparation and after apical enlargement (P > .05). Both systems promoted centered canals (P > .05).

CONCLUSIONS

HFEDM instruments promoted greater volume of the root canal than PDL. However, the cleaning ability of the instruments was similar. The apical increase up to size 40 with both instruments provided less debris and untouched surfaces and allowed centralization of the curved root canals.

Second Class Functional Treatment: Andreasen Activator vs Twin Block

Aim

The purpose of this research is to analyze and compare the dental and skeletal changes induced by two functional devices, Andreasen Activator and Clark's twin block, on the sagittal and vertical plane, by means of cephalometric analysis, of the lateral cephalograms prescribed at the beginning and at the end of the treatment for a second skeletal class, first division with normal or deep bite.

Materials and methods

Twenty patients, 8 females and 12 males, fulfilling criteria for inclusion, were divided randomly into two groups: group I was treated with Andreasen activator, the second group with Clark's twin block. The duration of the therapy was about 18 months plus less 2 months. Pretreatment and posttreatment cephalometric radiographs were analyzed using angular (SNA, SNB, ANB, SnaSnp–GoGn angles), linear (Sna–Snp, Co–Gn, Co–Go, Go–Gn) skeletal parameters and dental one (U1–SnaSnp angle, L1–GoGn angle, Overjet and Overbite). To evaluate the posttreatment changes in the single groups and between them, paired and unpaired t-test was used.

Results

In both of the two groups analyzed, all the sagittal and vertical, angular and linear, skeletal measurements appear to be increased in a statistically significant way, except SNA angle and the distance Sna–Snp. Regarding the dental parameters, in the group treated with Andreasen activator, only Overjet and Overbite showed statistically significant differences. On the other hand, twin block induced statistical changes about Overjet, Overbite and also U1/SnaSnp, but not about L1/GoGn. The advancement of the mandible determines a greater prominence of the chin and lower lip, an increment of the labial mental angle and a reduction of the convexity of the profile. Also, the decrease of the overjet and, consequently, of the dental exposure improve the esthetic appearance of the patient's face.

Conclusion

Both functional treatments showed a lower jaw advanced on the sagittal plane and increased in size. In the upper jaw no significant changes were observed. It was also evident a dental compensation both on sagittal and vertical planes.

Clinical significance

The functional devices studied, Andreasen activator and twin block, seem to obtain more skeletal than dental results when the patients were treated at the peak of pubertal growth.

How to cite this article

Baccaglione G, Rota E, Ferrari M, et al. Second Class Functional Treatment: Andreasen Activator vs Twin Block. Int J Clin Pediatr Dent 2020;13(2):144–149.

Relationship between the Position of the Incisors and the Thickness of the Soft Tissues in the Upper Jaw: Cephalometric Evaluation

Aim

The aim of this study is to verify if the thickness of soft tissues and inclination of the incisors have some relation with profile, to analyze its relevance considering these two parameters separately and to screen how the combination of different inclinations and different thickness can generate different facial patterns.

Materials and methods

The study was performed on 47 Caucasian patients aged between 6 years and 16 years of divided into 24 males and 23 females. None of the patients presented craniofacial changes of syndromic nature. All patients presented a value of SNA in between 80° and 84°. The inclination of the upper incisor related to the bispinal plane was between 104° and 116°. Each radiograph has been digitized or analyzed directly in digital format. To analyze the relationships between soft tissues and position of the incisors using various cephalometric measures and statistical methodology were used.

Results

Analysing the general correlation between all the cephalometric parameters considered, the results found show that the thickness of the tissues had an effect in modifying the aesthetic profile with respect to the position of the incisors. The cephalometric parameters related to the esthetic profile of the maxilla are all linked by strong correlations, especially correlation between SU, ULA and LS were very high. The differences between the means were statistically significant for different groups. Using the values of Mx1 and thickness of the lip as independent variables, while the LS, SU, ULA and NLA values as dependent variables all results are significant with respect to the prediction p < 0.05.

Conclusion

Thickness of the soft tissues showed a significant influence on the profile with respect to the position of the incisors.

Clinical significance

Data obtained highlighted that thickness of the soft tissues must be taken into account before starting an orthodontic treatment in order to obtain best aesthetic results.

How to cite this article

Maddalone M, Losi F, Rota E, et al. Relationship between the Position of the Incisors and the Thickness of the Soft Tissues in the Upper Jaw: Cephalometric Evaluation. Int J Clin Pediatr Dent 2019;12(5):391-397.

Nickel-Titanium Rotary File Systems: What's New?

Ever since their introduction, nickel–titanium (NiTi) alloys have continued to revolutionize the field of endodontics. They have considerable advantages over the conventional stainless steel file in terms of mechanical properties. However, despite of their superior mechanical properties, NiTi alloys still pose some risk of fracture. Consequently, there has been considerable research conducted to investigate the mechanisms behind the occurrence of these procedural errors. Since the last decade, different proprietary processing procedures have been introduced to further improve the mechanical properties of NiTi alloys. These treatments include thermal, mechanical, electropolishing, and recently introduced electric discharge machining. The main purpose of these treatments is to impart a more martensitic phase into the files at normal body temperature, so that the maximum advantage of flexibility can be obtained. These heat-treated instruments also possess improved cyclic fatigue resistance when compared to conventional NiTi alloys. NiTi alloys can be subclassified as the instruments mainly containing austenitic phase (conventional NiTi, M-wire, R-phase), and those containing martensitic phase (controlled memory wire, ProTaper Gold, and Vortex Blue). Instruments based on austenitic alloys possess superelastic properties due to the stress-induced martensitic transformation. Contrary to this, martensitic alloys can easily be deformed due to phase transformation, and they can demonstrate the shape memory effect when heated. This review discusses the different phase transformations and heat treatments that the NiTi instruments undergo.

Antibacterial Efficacy of Synthetic and Natural-Derived Novel Endodontic Irrigant Solutions

The aim of this study was to compare the efficacy of grape seed extract (GSE), calcium hypochlorite [Ca(ClO)2], and sodium hypochlorite (NaOCl) irrigant solutions with rotary or reciprocating instrumentation for disinfection of root canals inoculated with Enterococcus faecalis. The mesiobuccal root canals of mandibular molars were prepared and inoculated with Enterococcus faecalis for 21 days. The roots were then randomly divided into the following eight experimental groups (n=11) according to the instrumentation technique and disinfection protocol: ProTaper Next or Reciproc R25 with sodium chloride (control group), 6% NaOCl, 6% Ca(ClO)2, or 50% GSE used for irrigation during instrumentation. The antimicrobial activity was determined on the basis of a reduction in colony-forming units (CFUs) counted on bacterial samples collected before and after root canal instrumentation and expressed as a percentage of reduction. Data were evaluated by two-way ANOVA followed by Tukey HSD post-hoc tests (p<0.05). No significant differences were observed in bacterial reduction between the ProTaper Next and Reciproc R25 systems (p>0.05), regardless of the irrigant solution used. Furthermore, all active solutions (6% NaOCl, 50% GSE, and 6% Ca(ClO)2) showed similar potential to reduce bacterial counts (p>0.05) and were significantly more effective than sodium chloride (control) (p<0.05). The results suggest that the GSE and Ca(ClO)2 have potential clinical application as irrigant solutions in endodontic therapy since they present bactericidal efficacy against Enterococcus faecalis.

A microcomputed tomography evaluation of the shaping ability of three thermally-treated nickel-titanium rotary file systems in curved canals

OBJECTIVE

To evaluate the shaping ability of three thermally-treated rotary nickel-titanium (NiTi) systems including ProTaper Next (PTN), HyFlex™ CM (HFCM) and HyFlex™ EDM (HFEDM) during root canal preparation in simulated root canals.

METHODS

A total of 45 simulated root canals were divided into three groups ( n = 15) and prepared with PTN, HFCM or HFEDM files up to size 25. Microcomputed tomography (microCT) was used to scan the specimens before and after instrumentation. Volume and diameter changes, transportations and centring ratios at 11 levels of the simulated root canals were measured and compared.

RESULTS

HFEDM caused significantly greater volume increases than HFCM and PTN in the entire root canal and in the apical and middle thirds. HFCM removed the least amount of resin in the coronal third compared with HFEDM and PTN. Overall, HFCM caused significantly less transportation in the apical 2 mm and was better centred than PTN in the apical 3 mm.

CONCLUSION

Under the conditions of this study, all systems prepared curved canals without significant shaping errors and instrument fracture. PTN and HFCM cut less resin than HFEDM. HFCM stayed centred apically and cut the least material coronally.