Efficiency of rotary nickel-titanium FlexMaster instruments compared with stainless steel hand K-Flexofile--Part 2. Cleaning effectiveness and instrumentation results in severely curved root canals of extracted teeth

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.

Comparison of cleaning effectiveness of single rotary file OneShape and reciprocating F2 Protaper with Protaper Universal sequence: A SEM analysis

Aim

This in vitro study intend to compare the cleaning effectiveness of Protaper universal sequence with reciprocating F2 Protaper and single rotary file One shape.

Materials and method

30 extracted human 1st mandibular molars were chosen for the analysis. Three NiTi file systems were used for mechanical preparation, ProTaper full sequence in rotary motion, single F2 Protaper file used in reciprocating motion, and One shape single file used in a circular motion. Irrigation was carried out after each instrument use using 5 ml of 5% NaOCl followed by normal saline. The root canal surface was evaluated at three different areas (coronal, middle and apical thirds) using Scanning Electron Microscopy. Debris and the Smear layer were evaluated. Data were analyzed statistically using the Friedman test and Kruskal-Wallis test (p ≤ 0.05).

Results

A statistically significant difference (p ≤ 0.05) was observed in the debris score of the Protaper universal group when the 3 thirds of the root were compared. Intergroup comparisons confirmed a statistically significant difference at the coronal and apical third of the roots when debris scores were evaluated. Intragroup comparison for the smear layer demonstrated a statistically significant difference (p ≤ 0.05) at all the 3 levels of the radicular canal for the 3 groups studied. Intergroup comparisons revealed a statistically significant difference (p ≤ 0.05) in the middle and apical 1/3rd when the smear layer was evaluated.

Conclusion

The Protaper full sequence group provided better results than Single F2 ProTaper and One shape groups when debris and smear layer removal was investigated.

Modalities of using endodontic nickel-titanium rotary instruments and factors influencing their implementation in dental practice

BACKGROUND

To establish the extent of using nickel titanium rotary instruments (NiTi-RIs), to identify reasons for using / not using NiTi-RIs, to explore usage modalities and to identify factors and measures that can increase implementation of NiTi-RIs in general dental practice.

METHODS

Two pilot questionnaires were conducted on academic staff members at College of Dentistry, Taibah University, general dentists (GDs) and endodontists to finalise the questionnaire. A sample size was calculated considering the expected and minimum accepted response rates (60 and 48%, respectively) and a 99.9% Confidence Level. The online-questionnaire was sent to 600 GDs and all endodontists (175) working in Saudi Arabia. A reminder was emailed after 10 weeks to encourage non-respondents to complete the questionnaire. Responses, were collected and converted into numerical data which were analysed using the Chi-square test (p = 0.05).

RESULTS

Significantly most respondents (71.9%) used NiTi-RIs (p < 0.001); with more endodontists (96.9%) than GDs (60%). Most users (62.5%) had been using NiTi-RIs for More than 3 years (p < 0001). The trend of using NiTi-RIs increased as participants' experience and the number of root-canal treatments performed per week increased (p = 0.021). While most respondents (45.3%) used NiTi-RIs because of faster root-canal preparation, the majority of non-users (85.3%) didn't do so because of high cost. The highest proportion (43.3%) reported better undergraduate education as the most important factor that can significantly increase NiTi-RIs usage. The majority (91.8%) prepared glide-path before using NiTi-RIs; especially with stainless steel hand-files (63.3%).

CONCLUSIONS

NiTi-RIs are relatively well adopted in Saudi dental practice. However, better education, especially during undergraduate training and lower cost can increase their usage. Overall, clinicians showed good awareness of NiTi-RIs usage aspects which reflected on usage modalities.

Curvature height and distance of MB canal of mandibular molar with Schneider angle and its comparison with canal access angle

Aim

To measure the proposed curvature height and distance of MB canal of mandibular molar with Schneider angle and its comparison with canal access angle both before and after instrumentation, and to compare among each other with multiple linear regression analysis.

Methodology

One hundred human mandibular first and second molars were used for the study. After endodontic access, a size 10 k-file was placed in the mesiobuccal canal extending to the apical foramen and radiographs were taken by using Radiovisiography. Both Schneider and canal access angle with its respective linear counterpart (Curvature height and curvature distance) was measured and calculated by using PLANMECA romexis (Helsinki Finland) software connected to the Intraoral x-ray unit both before and after biomechanical preparation with mesiobuccal canal till size F2. Statistical analysis was done by using multiple linear regression analysis.

Results

A significant difference was observed between before and after enlargement with respect to Schneider angle and Canal access angle with a t-value being (t = 11.0629, p < 0.05) (t = 10.5773, p < 0.05) for before and after enlargement of canals respectively. Percent of change is observed more with curvature height (29.62%) as compared with the curvature distance (8.87%).

Conclusions

Schneider angle with its proposed curvature height and distance reduced after instrumentation. Whereas canal access angle decreased and its curvature height and distance have increased after instrumentation.

Ex-vivo Smear Layer Removal Efficacy of Two Activated Irrigation Techniques After Reciprocating Instrumentation in Curved Canals

Introduction:

This study aimed to compare the effectiveness of two activated irrigation techniques in removing the smear layer after single-file reciprocating instrumentation in curved canals.

Materials and Methods:

Sixty distobuccal roots of maxillary molars were standardized to create a closed system, and then instrumented using WaveOne Primary (Dentsply Maillefer, Ballaigues, Switzerland) instruments. Fifty-four specimens were randomly distributed into 3 groups for final irrigation: Non-activated irrigation, passive ultrasonic irrigation (PUI), and EndoActivator (EA;Dentsply Maillefer, Tulsa, USA) irrigation. All specimens received 3 mL of 17% EDTA for 1 minute, followed by irrigation with 6 mL of 2.5% NaOCl. The apical, middle and cervical thirds of the specimens were analyzed using scanning electronic microscopy (SEM), and the amount of remaining smear layer on the canal walls was rated by three examiners using a five-category scoring system. Kendall’s concordance coefficient was used to assess inter-rater agreement. Kruskal-Wallis and Mann-Whitney (Bonferroni) tests were used to compare the scores.

Results:

Kendall’s concordance coefficient was ≥ 0.7, indicating an excellent level of agreement between the raters. No statistically significant difference in irrigation techniques efficacy for removal of the smear layer (p=0.061) was found for the apical third. The scores attributed to the specimens irrigated with the EA system were significantly lower than those of the other groups in the cervical and middle thirds (p< 0.05).

Conclusions:

The efficacy of the EA system in removing the smear layer in the cervical and middle thirds of root canals instrumented with reciprocating motion was significantly higher than that of either PUI or non-activated irrigation. Both EA and PUI performed similarly in apical third.

In Vivo and In Vitro Effectiveness of Rotary Nickel-Titanium vs Manual Stainless Steel Instruments for Root Canal Therapy: Systematic Review and Meta-analysis

INTRODUCTION

This systematic review evaluated the effectiveness of nickel-titanium (NiTi) rotary files compared to stainless-steel (SST) hand files.

METHODS

An electronic search was performed on Medline, EMBASE, CENTRAL and Scopus databases up to February 2016. An additional hand searching was performed in 13 journals. The studies were classified according to study type and the outcome variables. Two reviewers independently applied eligibility criteria, extracted data, and three reviewers independently assessed the quality of the evidence of each included study according to The Cochrane Collaboration's procedures. A meta-analysis was performed whenever it was possible.

RESULTS

The electronic and hand search strategies yielded 1155 references of studies after removal of duplicates. Four clinical studies (two prospective and two retrospective studies) and 18 in vitro studies (on extracted teeth) were included for the qualitative synthesis after full-text evaluation of the eligible studies. The overall level of methodological quality of the studies included can be considered inadequate. Only one clinical study was judged at low risk of bias, whereas most non-clinical studies had a low risk of bias. Three meta-analyses, based on a very limited number of studies, could be performed. Each meta-analysis contained two studies. Of these, one meta-analysis was based on clinical studies.

CONCLUSIONS

The results of this systematic review suggested that NiTi rotary instruments were associated with lower canal transportation and apical extrusion when compared to SST hand files, whereas both groups had similar outcomes in terms of success of therapy, amount of residual bacteria, and cleansing ability after treatment. However, due to the limited evidence available, these results should be interpreted with caution. Consequently, more randomized control trials using standardized protocols are needed in order to provide more solid recommendations.

Assessment of the Amount of Calcium Ions Released after the use of Different Chelating Agents and Agitation Protocols

Background:

The main goal of endodontic treatment is to achieve cleaning and shaping prior to the filling process.

Objective:

This study aimed to evaluate, using atomic absorption spectrometry, the release of Calcium ions after the use of different chelating agents and protocols of agitation.

Method:

Ninety human canine teeth were randomly assigned to one of nine groups (n=10), as follows: 1) 0.2% Chitosan and manual agitation; 2) 0.2% Chitosan and sonic agitation; 3) 0.2% Chitosan and ultrasonic agitation; 4) 17% EDTA and manual agitation; 5) 17% EDTA and sonic agitation; 6) 17% EDTA and ultrasonic agitation; 7) distilled water and manual agitation; 8) distilled water and sonic agitation; 9) distilled water and ultrasonic agitation. Following instrumentation, all chelating substances remained inside the root canal for 3 min. Then the fluid was collected for the identification and quantification of Calcium ions. The amount of Calcium ions released in each group was compared using analysis of variance (ANOVA) and the Kolmogorov-Smirnov and Levene tests followed by Tukey’s post-hoc test. Significance was set at 5%.

Results:

The groups in which 0.2% Chitosan was used showed the highest concentration of Calcium ions (p<0.05). Concerning the agitation method, ultrasonic agitation showed the greatest values, followed by sonic and manual agitation (all comparisons, p<0.05).

Conclusion:

The present findings suggest that, among the combinations here tested, Chitosan associated with ultrasonic agitation yielded the greatest release of Calcium ions.

Ultrasonic versus sonic activation of the final irrigant in root canals instrumented with rotary/reciprocating files: An in-vitro scanning electron microscopy analysis

Aim:

To compare the smear layer and debris removal in root canals instrumented with two different kinematic motions after ultrasonic and sonic irrigation activation.

Materials and Methods:

Eighty freshly extracted teeth were selected for the study and randomly divided the samples into two groups (n = 40) for instrumentation with either rotary ProTaper NEXT (PTN) or reciprocating WaveOne (WO) file systems. These (n = 40) were further divided into two groups (n = 20) where the final irrigant was activated using either Ultrasonics (Passive Ultrasonic Irrigation; PUI) or Sonics (EndoActivator; EA). Group 1: PTN + EA; Group 2: PTN + PUI; Group 3: WO + EA; and Group 4: WO + PUI. During instrumentation, a total of 4 ml of 5.25% NaOCl was used for irrigation. The final irrigation protocol included NaOCl and Smear Clear Solution. The samples were processed by scanning electron microscopic examination for debris and smear layer scoring, and statistical analysis was done.

Results:

The mean debris and smear layer score was less in the group instrumented by PTN with sonic activation of the irrigant.

Conclusion:

A combination of PTN instrumentation with sonic irrigation activation by EA is more effective in debris and smear layer removal in the groups tested.

Effectiveness of XP-endo Finisher, EndoActivator, and File agitation on debris and smear layer removal in curved root canals: a comparative study

The purpose of this study was to assess the efficacy of the XP-endo Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) file on debris and smear layer removal in curved root canals in comparison to different irrigation regimens. Seventy-five freshly extracted human mandibular molar teeth with mesial root curved more than 20° were used in this study. The mesial root canals were mechanically prepared using the BT-Race rotary system (FKG Dentaire) and divided into five groups (n = 15) according to the following irrigation techniques: positive control, non-agitated, File agitation, XP-endo Finisher, and EndoActivator (Dentsply Tulsa Dental Specialities, Tulsa, OK, USA). Root canals were split longitudinally and evaluated by scanning electron microscopy. Five-grade scoring system was used to assess the presence of debris and smear layer at the coronal, middle, and apical regions. The XP-endo Finisher and EndoActivator groups revealed significantly lower debris and smear layer scores than the other groups at the coronal, middle, and apical regions (P < 0.05). There was no significant difference between XP-endo Finisher and EndoActivator groups (P > 0.05). The apical region had higher debris and smear layer scores compared with the coronal regions in all groups (P < 0.05), except for the positive control group; there was no significant difference between the three regions of the root canal (P > 0.05). Irrigation of curved root canals using XP-endo Finisher and EndoActivator methods appears to be more effective on debris and smear layer removal than the other tested groups.

Evaluation of Root Canal Preparation Using Rotary System and Hand Instruments Assessed by Micro-Computed Tomography

Background

Complete mechanical preparation of the root canal system is rarely achieved. Therefore, the purpose of this study was to evaluate and compare the root canal shaping efficacy of ProTaper rotary files and standard stainless steel K-files using micro-computed tomography.

Material/Methods

Sixty extracted upper second premolars were selected and divided into 2 groups of 30 teeth each. Before preparation, all samples were scanned by micro-computed tomography. Thirty teeth were prepared with the ProTaper system and the other 30 with stainless steel files. After preparation, the untouched surface and root canal straightening were evaluated with micro-computed tomography. The percentage of untouched root canal surface was calculated in the coronal, middle, and apical parts of the canal. We also calculated straightening of the canal after root canal preparation. Results from the 2 groups were statistically compared using the Minitab statistical package.

Results

ProTaper rotary files left less untouched root canal surface compared with manual preparation in coronal, middle, and apical sector (p<0.001). Similarly, there was a statistically significant difference in root canal straightening after preparation between the techniques (p<0.001).

Conclusions

Neither manual nor rotary techniques completely prepared the root canal, and both techniques caused slight straightening of the root canal.

Radiographic assessment and chair time of rotary instruments in the pulpectomy of primary second molar teeth: a randomized controlled clinical trial

Background and aims. The superiority of rotary systems has been reported in several clinical studies on permanent teeth. This study consisted of radiographic assessment and chair time of rotary instruments in the pulpectomy of primary second molar teeth.

Materials and methods. In this randomized controlled clinical study, 46 children, 3-6 years of age, were selected. The patients were divided randomly into two groups. In the first group (group A) pulpectomy was carried out with hand instruments and in the second group (group B) the Rotary FlexMaster System was used. T-test and chi-squared test were used to analyze data.

Results. The mean instrumentation time in group A was significantly more than that in group B (P<0.001). Also there was a significant difference between both groups in relation to the distance between the apex of mesial root (P<0.001) and distal root (P=0.007) and the canal filling level.

Conclusion. Superior radiographic findings and less chair time of pulpectomy with rotary instruments in second primary molar teeth were achieved.

A survey of adoption of endodontic nickel-titanium rotary instrumentation part 2: community and hospital dental practitioners in Wales

OBJECTIVES

To assess adoption of endodontic nickel-titanium rotary technology (NiTi) by community and hospital dental clinicians within Wales and identify factors that may restrict uptake.

DESIGN

Postal questionnaire.

SETTING

Community and hospital-based dentists in Wales.

METHODS

Community and hospital-based dentists with a remit for provision of restorative dentistry (community dental setting = 32; hospital dental setting = 36) were approached regarding their usage or otherwise of nickel-titanium rotary instrumentation for endodontic treatments. The postal questionnaire took the form of an anonymous survey comprising 12 questions. These questions covered usage parameters, satisfaction and training and broached reasons for NiTi avoidance.

RESULTS

The response rate was 77%. NiTi rotary instruments were used routinely by an encouraging 82% of those in the hospital-based restorative dental services but only 13% of community staff. Factors cited as being implicated in the decision to avoid their use included cost (62% of responses) lack of training and the perceived lack of benefit.

CONCLUSION

The adoption of rotary NiTi endodontic technology by the hospital dental practitioners of Wales is encouraging with the majority having converted to such systems in excess of three years prior to the survey. There was, however, a significant disparity in NiTi usage between community and hospital settings, the implications for which and possible solutions for increased training and uptake are discussed.

Comparison of the efficacy of Smear Clear with and without a canal brush in smear layer and debris removal from instrumented root canal using WaveOne versus ProTaper: a scanning electron microscopic study

INTRODUCTION

The aim of this study was to compare by scanning electron microscopy the presence of smear layer and debris on root canal walls after preparation with the single-file system WaveOne (Dentsply Maillefer, Ballaigues, Switzerland) versus the rotary ProTaper system (Dentsply Maillefer, Ballaigues, Switzerland) under 2 final irrigant regimens.

METHODS

Forty freshly extracted single-rooted human teeth were randomly divided into 4 groups (n = 10). The ProTaper and ProTaper and rotary CanalBrush (Coltène Whaledent GmbH+ Co KG, Langenau, Germany) groups were instrumented with the ProTaper system. Groups WaveOne and WaveOne and rotary CanalBrush were instrumented with the WaveOne system. The irrigant in all groups was 2 mL 5.25% sodium hypochlorite (NaOCl) solution, whereas the final irrigation after preparation in the ProTaper and WaveOne groups was 1 mL Smear Clear solution (Sybron Endo, Orange, CA) and then 5.25% NaOCl applied with a plastic syringe, and in the ProTaper and rotary CanalBrush and WaveOne and rotary CanalBrush groups, it was 1 mL Smear Clear solution and then 5.25% NaOCl (rotary CanalBrush agitation). Roots were processed for scanning electron microscopic examination for debris and smear layer scoring. Data were statistically analyzed.

RESULTS

All groups showed more efficient smear layer and debris removal coronally than in the middle and apical regions, whereas the mean total debris score and the mean smear layer score in all groups were less in the WaveOne and rotary CanalBrush groups than the ProTaper and rotary CanalBrush and the WaveOne and ProTaper groups.

CONCLUSIONS

Using the rotary CanalBrush in canals prepared with WaveOne produced the cleanest canal walls, and the WaveOne system gave superior results compared with the ProTaper system.

Comparison of influence of different manufacturing methods on the cleaning efficiency of rotary nickel-titanium files

The purpose of this study was to evaluate and compare cleaning effectiveness of TwistedFile, GT series X, Revo-S, RaCe, Mtwo, and ProTaper Universal rotary files in curved canals. Seventy mesiobuccal canals of extracted human first maxillary molars were divided into seven groups of 10 samples each. Canals were prepared with six nickel-titanium (NiTi) rotary systems and manual K-Flexofile. Irrigation was performed with 2 mL 2.5% NaOCl solution after each file, and 5 mL 2.5% NaOCl was used for the final flush. After the roots were split longitudinally, the presence of debris and smear layer was visualized using scanning electron microscopic photomicrographs taken at coronal, middle, and apical third. Mean scores for debris and the smear layer were calculated and statistically analyzed for significance between groups using the Kruskal-Wallis nonparametric analysis of variance (P < 0.05) and Mann-Whitney U test (P < 0.001). There was no significant difference among the groups in terms of debris and smear layer scores (P > 0.05). Without considering the preparation method used, while no statistically significant difference was found between the coronal third and the middle third (P > 0.05), higher amount of debris and smear layer were found in apical third (P = 0.001). The new generation of NiTi rotary files including the Twisted File and GT Series X presented similar cleaning effectiveness compared with traditionally ground NiTi rotary files.

Effect of ultrasonication with EDTA or MTAD on smear layer, debris and erosion scores

The purpose of this study was to compare the effects of ultrasonication with ethylenediaminetetraacetic acid (EDTA) and a mixture of tetracycline isomer, an acid, and a detergent (MTAD) as final canal irrigants on the smear layer, debris and erosion scores. Fifty-eight extracted single-rooted human teeth were instrumented with ProTaper rotary files up to size F3. According to the final irrigation regimen, the samples were distributed into the following groups: EDTA, MTAD, EDTA ultrasonicated for 1 min, and MTAD ultrasonicated for 1 min. The smear layer, debris and erosion scores were recorded at the apical, middle, and coronal third of each canal using a scanning electron microscope. Data were subjected to statistical evaluation using the Kruskal-Wallis and Mann-Whitney tests (P < 0.05). There were no significant differences in smear layer or debris removal between the experimental groups. EDTA caused significantly more erosion at the middle level than MTAD. Also EDTA resulted in more erosion at the coronal level than MTAD when subjected to ultrasonication. Ultrasonic activation of EDTA significantly increased its erosive effects at the middle and coronal levels. Based on the present findings, MTAD appears to cause less dentinal erosion while allowing proper removal of the smear layer and debris.

Histological analysis of cleaning efficacy of hand and rotary instruments in the apical third of the root canal: A comparative study

AIM

To compare the cleaning efficiency of manual and rotary instrumentation in the apical third of the root canal system.

MATERIALS AND METHODS

In group 1 (n=10), instrumentation was performed with stainless steel K-file; in group 2 (n=10), it was done with hand ProTaper files; and in group 3 (n=10), instrumentation was done with ProTaper rotary. Distilled water was used for irrigation. The apical third was sectioned transversally and histologically processed. The cross sections were examined under optic microscope and debris was measured using Motic software.

RESULTS

Instrumentation with stainless steel K-files showed minimum amount of debris, followed by ProTaper hand files, and rotary ProTaper files were least effective with maximum amount of debris; however, there were no significant differences between the three experimental groups.

CONCLUSIONS

Both the manual and rotary instrumentation are relatively efficient in cleaning the apical third of the root canal system and the choice between manual and rotary instrumentation should depend on case to case basis.

Removal of surgical smear layer

INTRODUCTION

During apicoectomy and retrograde cavity preparation, a smear layer, which contains microorganisms and necrotic pulpal tissues, is formed on the dentinal surfaces cut by the instruments. Bacteria can survive and proliferate inside or below the smear layer. The purpose of this study was to evaluate in vitro two different procedures for the removal of the smear layer in retrocavities prepared with ultrasonic retrotips.

METHODS

Twenty-eight single-rooted teeth were cleaned, shaped, and obturated with gutta-percha and sealer. The apical 3 mm of each root were cut with a carbide bur, and retrograde cavities were prepared with ProUltra ultrasonic retrotips (Maillefer Dentsply, Baillagues, Switzerland) at a depth of 3 mm. Teeth in group A were treated with a gel of 35% orthophosphoric acid for 15 seconds, and teeth in group B were treated with a gel of 24% EDTA at a neutral pH for 2 minutes. The samples were prepared for scanning electron microscopic observation and scored for the presence of the smear layer on the retrocavity walls.

RESULTS

Eighty percent of the teeth in group A showed an optimal degree of cleanliness of the walls, with dentinal tubules completely open. The majority of analyzed samples coming from group B showed dentinal tubules covered with the smear layer.

CONCLUSIONS

The analysis of the samples showed that orthophosphoric acid is more effective than EDTA in removing surgical smear layer even with less time of action.

Comparative evaluation of surface characteristics of dentinal walls with and without using plastic finishing file

Aim:

The aim of this in vitro research is to evaluate the debris present on the dentinal walls after instrumentation in mesiobuccal root of maxillary molar with Hand Protapers, Hand Profiles, Hand Hero Shapers, and finishing the dentinal walls with and without rotary plastic files using stereomicroscope.

Materials and Methods:

Sixty freshly extracted human maxillary first molar teeth were divided into two groups of 30 teeth each (group A and B). Both the groups were divided into three subgroups of 10 teeth each (group A had subgroups A1, A2, and A3) and (group B had subgroups B1, B2 and B3). In group A, all the 30 canals were subjected to cleaning and shaping with three different instruments system and kept unfinished. This group was named as unfinished group. In group B, all the 30 canals were subjected to cleaning and shaping with three different instruments system followed by finishing with plastic files. This group was named as finished group. The crown of each tooth was sectioned at the cementoenamel junction. Canals were prepared following conventional principles of crown down technique. After splitting the roots longitudinally, the dentinal debris of each root canal was evaluated in three areas (coronal, middle and apical thirds of the root) by means of numerical evaluation scale, using a stereomicroscope.

Results:

Stereomicroscopic evaluations showed that there was no significant difference in the debris scores between the subgroups when the canals were instrumented with hand Protaper, hand Profile and hand Hero Shaper in all the thirds. There was no significant difference in scores between the unfinished group and the finished group in the coronal third but significant differences were seen in middle third and apical third.

Conclusions:

After instrumentation with different hand instruments, the use of plastic finishing files showed cleaner canal walls.

Cleanliness in the Root Canal System: An Scanning Electron Microscopic Evaluation of Manual and Automated Instrumentation using 4% Sodium Hypochlorite and EDTA (Glyde File Prep)-An in vitro Study

Aim : To assess the cleaning efficacy of manual and automated instrumentation using 4% sodium hypochlorite singly and in combination with Glyde file Prep as root canal irrigant.

Methodology : The study utilized 40 extracted human permanent premolars with single, straight and fully formed root. The teeth were then divided into four groups of ten each, Group I and II were prepared by manual instruments with 4% sodium hypochlorite used as irrigant singly [Group I] or in combination with Glyde file prep. Group III and IV were prepared by automated instruments at 250 rpm with 4% sodium hypochlorite as irrigant singly [Group III] and in combination with glyde file prep [Group IV] automated instrumentation. After completion of the root canal preparation the canal, teeth were prepared for SEM examination. These photomicrographs were qualitatively evaluated using criteria. Overall cleanliness, presence or absence of the smear layer, presence or absence of the debris, patency of the opening of dentinal tubules.

Results : When comparing the cleansing efficacy of manual and automated instrumentation using 4% sodium hypochlorite better cleansing was there with manual instrumentation. When comparing the cleansing efficacy of manual and automated instrumentation using combination regime cleansing is better with automated instrumentation. When comparing the cleansing efficacy of manual instrumentation using 4% sodium hypochlorite singly and in combination with EDTA, the combination regime led to better cleansing. When comparing the cleansing efficacy of automated instrumentation using 4% sodium hypochlorite singly and in combination regime lead to better cleansing.

Conclusion : Neither of instrumentation technique, nor irrigating regimes were capable of providing a completely clean canal. Automated instrumentation with a combination of sodium hypochlorite & EDTA resulted the best cleansing efficacy.

Ex vivo study on root canal instrumentation of two rotary nickel-titanium systems in comparison to stainless steel hand instruments

AIM

To investigate instrumentation time, working safety and the shaping ability of two rotary nickel-titanium (NiTi) systems (Alpha System and ProTaper Universal) in comparison to stainless steel hand instruments.

METHODOLOGY

A total of 45 mesial root canals of extracted human mandibular molars were selected. On the basis of the degree of curvature the matched teeth were allocated randomly into three groups of 15 teeth each. In group 1 root canals were prepared to size 30 using a standardized manual preparation technique; in group 2 and 3 rotary NiTi instruments were used following the manufacturers' instructions. Instrumentation time and procedural errors were recorded. With the aid of pre- and postoperative radiographs, apical straightening of the canal curvature was determined. Photographs of the coronal, middle and apical cross-sections of the pre- and postoperative canals were taken, and superimposed using a standard software. Based on these composite images the portion of uninstrumented canal walls was evaluated.

RESULTS

Active instrumentation time of the Alpha System was significantly reduced compared with ProTaper Universal and hand instrumentation (P < 0.05; anova). No instrument fractures occurred in any of the groups. The Alpha System revealed significantly less apical straightening compared with the other instruments (P < 0.05; Mann-Whitney U test). In the apical cross-sections Alpha System resulted in significantly less uninstrumented canal walls compared with stainless steel files (P < 0.05; chi-squared test).

CONCLUSION

Despite the demonstrated differences between the systems, an apical straightening effect could not be prevented; areas of uninstrumented root canal wall were left in all regions using the various systems.

A comparative scanning electron microscopic study of the effect of three different rotary instruments on smear layer formation

The aim of this study was to evaluate the effect of RaCe, FlexMaster and ProFile rotary instruments on smear layer formation by scanning electron microscopy. Eighty-four caries-free freshly extracted human single-rooted teeth were selected and divided into three groups, each containing 28 teeth. The teeth were instrumented with rotary instruments sequentially: Group A: ProFile Rotary Instruments; Group B: FlexMaster Rotary Instruments; and Group C: RaCe Rotary Instruments. Instrumentation was performed by the crown-down method and according to the manufacturer's instructions. The specimens were then examined with SEM according to Hülsmann's classification. One-way ANOVA and a post hoc Tukey test were used for statistical analysis. The results showed that there were no statistically significant differences among the three groups in the coronal third (P = 0.39), but at the apical and middle thirds there were statistically significant differences between the RaCe group and the other groups (P < 0.05). Smear layer in the RaCe group was less than that in the ProFile and FlexMaster groups, but the difference between the ProFile group and FlexMaster group was not statistically significant (P > 0.05). It was concluded that RaCe Rotary Instruments produce less smear layer than FlexMaster and ProFile Rotary Instruments.

Scanning electron microscopic evaluation of debris and smear layer remaining following use of ProTaper and Hero Shaper instruments in combination with NaOCl and EDTA irrigation

OBJECTIVE

The purpose of this study was to evaluate the amounts of debris and smear layer remaining on canal walls after preparation with ProTaper and Hero Shaper instruments in combination with NaOCl and EDTA irrigation in curved root canals.

STUDY DESIGN

A total of 55 root canals were randomly divided into 2 instrumentation groups of 20 canals each and 1 negative control group of 15 canals. The canals in each of the 2 instrumentation groups were prepared with ProTaper or Hero Shaper instruments. Irrigation was performed with 5% NaOCl and 17% EDTA solutions. The control group was not instrumented. The remaining debris and smear layer were evaluated from scanning electron photomicrographs at x200 and x1,000 magnification taken in the coronal, middle, and apical thirds of the canals at both inner and outer canal walls. A 5-category scoring system for debris and smear layer was used. Statistical analysis was carried out using the Kruskal-Wallis and Mann-Whitney rank sum tests.

RESULTS

Completely clean root canals were not found in either instrumentation group. In the coronal and middle thirds, the canal walls of both instrumentation groups were clean, with no or only small areas of debris and smear layer. In the apical region, there were higher scores in terms of debris and smear layer in both instrumentation groups. No significant difference was found at the inner wall of the 2 instrumentation groups in terms of debris mean score. However, the outer canal walls prepared with ProTaper showed lower debris score compared with those prepared with Hero Shaper (P < 0.001). Concerning the smear layer, both the inner and outer canal walls prepared with ProTaper showed lower mean scores compared with those prepared with Hero Shaper (P < 0.001).

CONCLUSIONS

Within the limitations of this study, both instruments in combination with NaOCl and EDTA irrigation produced a clean and debris-free canal surface in the coronal and middle thirds, but were unable to produce a canal surface free from debris and smear layer in the apical third. However, the canals prepared with ProTaper instruments showed smaller amounts of debris and smear layer remaining in the apical region.

A comparative SEM investigation of the smear layer following preparation of root canals using nickel titanium rotary and hand instruments

The aim of this study was to compare the efficacy of NiTi flex K-file instruments and rotary FlexMaster and Race instruments (short for reamers with Alternating Cutting Edges) in root canal preparation. A total of 75 single rooted teeth with minimum curvature (< 5 degrees ) were selected and divided into three groups, each containing 25 teeth. Canals were prepared with NiTi flex K-file, FlexMaster and Race instruments using crown down preparation technique, up to size #40. After each instrument, the root canals were flushed with 5 ml of 0.5% NaOCl solution. The amount of debris and smear layer was quantified on the basis of Hulsmann method using a scanning electron microscope. Completely cleaned root canals were not found after instrumentation with any of the three instruments. In general, FlexMaster instruments left significantly less debris and smear layer than Race and NiTi flex K-file instruments (P < 0.05). NiTi flex K-files resulted in significantly more smear layer (P < 0.05) compared to Race and FlexMaster instruments only in the apical third of the canal.

Preparation of the coronal and middle third of oval root canals with a rotary or an oscillating system

OBJECTIVES

To comparatively evaluate the preparation of oval root canals with a rotary or an oscillating system.

STUDY DESIGN

The middle and coronal parts of 55 extracted permanent teeth with oval canals were prepared using FlexMaster (FM) rotary NiTi instruments and EndoEze AET (EE) stainless steel oscillating instruments. Pre- and postoperative images of cross-sections were superimposed to identify shifts in the center and to assess the percentage of untreated regions. In addition, the middle segment was investigated by scanning electron microscope (SEM) to determine debris and smear layer removal.

RESULTS

The systems did not significantly differ in the shifts of the canal centers in the middle part of the root. Only a few of the preparations yielded an excellent result with no uninstrumented canal wall left. The SEM investigation demonstrated poor results for both systems regarding debris and smear layer removal, but no significant differences could be observed.

CONCLUSIONS

Neither FM nor EE was capable of completely preparing oval root canals.

Shaping ability of progressive versus constant taper instruments in curved root canals of extracted teeth

AIM

To compare the shaping ability of progressive versus constant taper shaft instruments in curved root canals of extracted human teeth.

METHODOLOGY

A total of 40 root canals of mandibular molars with curvatures ranging between 20 degrees and 40 degrees were divided into two groups of 20 canals each and embedded in a muffle system. The root canals sectioned horizontally at three levels before preparation and then remounted into the mould. All root canals were prepared with ProTaper (progressive taper) or Hero Shaper (constant taper) instruments. Pre- and post-instrumentation radiographs and cross-sectional images were obtained. The parameters evaluated were: working safety (instrument failure, apical blockage and loss of working length) and shaping ability (straightening, cross-sectional area, transportation and centring ability). The data were analysed statistically using Student's t-test.

RESULTS

No instrument fractured during preparation. One Hero Shaper instrument permanently deformed. Both instrument systems maintained working length well. The canals prepared with Hero Shaper instruments were straightened to a lesser degree (P < 0.05). ProTaper instruments removed more dentine in the coronal and the middle sections of the canals. Canals prepared with Hero Shaper instruments had less transportation (P < 0.01) and better centring ability (P < 0.05) in the apical section.

CONCLUSIONS

Both instrument systems were safe to use and maintained working length well. The canals prepared with Hero Shaper had less transportation and were better centred in the apical region, possibly because their smaller taper reduced instrument stiffness.

The principles of techniques for cleaning root canals

Chemomechanical preparation of the root canal includes both mechanical instrumentation and antibacterial irrigation, and is principally directed toward the elimination of micro-organisms from the root canal system. A variety of instruments and techniques have been developed and described for this critical stage of root canal treatment. Since their introduction in 1988, nickel-titanium (NiTi) rotary instruments have become a mainstay in clinical endodontics because of their exceptional ability to shape root canals with potentially fewer procedural complications. Safe clinical usage of NiTi instruments requires an understanding of basic metallurgy of the alloy including fracture mechanisms and their correlation to canal anatomy. This paper reviews the biologic principles of preparing root canals with an emphasis on correct use of current rotary NiTi instrumentation techniques and systems. The role and properties of contemporary root canal irrigants is also discussed.

The Effectiveness of Different Acid Irrigating Solutions in Root Canal Cleaning After Hand and Rotary Instrumentation

The goal of this study was to evaluate the cleaning ability of three acid irrigating solutions after hand and rotary instrumentation. Eighty human teeth were randomly divided in eight groups. Four groups were prepared with hand instrumentation and other four with ProTaper. The irrigating solutions were 15% citric acid plus 2.5% NaOCl; 15% EDTA plus 2.5% NaOCl; 5% orthophosphoric acid plus 2.5% NaOCl; and 2.5% NaOCl alone as control. Canal walls were observed with scanning electron microscopy, and photomicrographs were taken in apical, middle, and coronal thirds. A scoring system for debris and smear layer was used. Acid solutions with 2.5% NaOCl were effective in the elimination of smear layer or debris, and no significant differences were showed in smear layer removal between techniques. However, 2.5% NaOCl did not remove smear layer or debris, and no significant differences in debris were observed between manual and rotary techniques.

Comparison of the shaping ability of RaCe and FlexMaster rotary nickel-titanium systems in simulated canals

The aim of this study was to compare the shaping ability of RaCe and FlexMaster rotary nickel-titanium instruments in simulated canals. A total of 80 canals with four different shapes were prepared with either RaCe or FlexMaster instruments. Pre- and postoperative images of each canal were recorded and combined using image analysis software. The development of canal aberrations and transportation was assessed. There was a significant difference (p < 0.001) between the systems for time of preparation to apical size 30, .06 taper; FlexMaster instruments took on average 1.86 min and RaCe 1.66 min. One RaCe and two FlexMaster instruments fractured. No zips, elbows, or danger zones were created. One perforation and eight outer widenings were created using FlexMaster instruments; RaCe instruments created two outer widenings. No differences were found between the instruments for direction of transportation. RaCe and FlexMaster nickel-titanium instruments prepared canals rapidly with few aberrations.

The management of periapical lesions in endodontically treated teeth

When root canal therapy is done according to accepted clinical principles and under aseptic conditions, the success rate is generally high. However, it has also been reported that 16% to 64.5% of endodontically treated teeth are associated with periapical radiolucent lesions. There are great variations among clinicians when suggesting treatment of these failed endodontic cases. This article will discuss factors influencing treatment decisions on these particular cases, and the pros and cons of nonsurgical retreatment versus surgical retreatment. The advancement of modern endodontic microsurgery will also be discussed.

Determination of root canal curvatures before and after canal preparation (part II): A method based on numeric calculus

The aim of this paper is to present a new method based on numeric calculus to provide data on any type of root canal curvature at any point of the long axis of the canal. Twenty severely curved, simulated root canals were prepared with rotary FlexMaster and Profile instruments in the crown-down technique and manually in the step-back technique. The inner and outer curvatures were registered in a system of coordinates before and after preparation in increments of 0.5 mm. Using an equalising function, the curvatures were first represented in graphic and algebraic form. The maximum and the mean curvature as well as the length of the arc from the apical foramen to the point of maximum curvature were determined mathematically. An increase in maximum curvature was registered for all four shaping systems investigated. The radius of the inner curvature decreased by 0.5-1.2 mm in the manual systems as a result of the preparation. The Profile system displayed the smallest changes in radius (-0.9 mm) even with the outer curvature, and manual preparation with stainless steel files the most pronounced change (-1.8 mm). The point of maximum curvature at the inner curvature was displaced by 1.6 mm to the apical foramen through manual preparation with Ni-Ti files. At the outer curvature, the maximum displacement (1.8 mm) recorded was also the result of preparation with Ni-Ti hand files, while a displacement of only 0.3 mm to the apical foramen was recorded with the other systems. The method offers a means of determining curvatures precisely without random specification of reference points. The method is also capable of registering only minor changes in curvature in the two-dimensional long axis of the canal.

A comparative study of root canal preparation with NiTi-TEE and K3 rotary Ni-Ti instruments

AIM

To evaluate and compare several parameters of curved root canal preparation using two different Ni-Ti systems: NiTi-TEE (Sjöding Sendoline, Kista, Sweden) and K3 (Sybron Endo, Orange County, CA, USA).

METHODOLOGY

Fifty extracted mandibular molars with mesial root canal curvatures ranging from 20 to 40 degrees were divided into two groups. In one group, 50 root canals were instrumented using NiTi-TEE files to an apical size 30; 0.04 taper (the largest available size at the time of this study). In the other group, 50 root canals were prepared with K3 instruments to an apical size 45; 02 taper. Both systems were used in a crowndown manner, with copious NaOCl (3%) irrigation and a chelating agent (Calcinase Slide, lege artis, Dettenhausen, Germany), employing torque-controlled motors. For assessment of shaping ability, pre- and postinstrumentation radiographs and cross-sectional photographs of canals were taken and changes in canal curvature and root canal diameter documented. Cleaning ability was evaluated by investigating specimens of the apical, medial and coronal third of the root canal wall under a scanning electron microscope using 5-score indices for debris and smear layer. Procedural errors (instrument separations, perforations, apical blockages, loss of working length) and working time were recorded. Nonparametric anova was used to compare straightening of canal curvatures, canal cross-sections and canal wall cleanliness (P < 0.05), whereas working time was analysed using the parametric anova (P < 0.05).

RESULTS

Both Ni-Ti systems maintained curvature well: the mean degree of straightening was 0.2 degrees for NiTi-TEE and 0.4 degrees for K3 with no statistical significance between the groups. Post-instrumentation cross-sections of the root canals revealed an acceptable contour (round or oval) in 50.6% of cases for the NiTi-TEE group and in 65.3% of cases for the K3 group. The difference was not significant. The SEM investigation of canal walls showed equally good debris removal for both systems: NiTi-TEE prepared canal walls in 74.7% of cases with scores I and II; K3 achieved these scores in 78.7% of cases. For smear layer, NiTi-TEE and K3 only received good scores (I and II) in 38.7% and 40% of canal wall specimens, respectively. For both parameters, no significant differences were found between groups. File fractures did not occur, but loss of working length was observed in one case following the preparation with NiTi-TEE and in three cases during K3 instrumentation. Mean working time was significantly shorter for NiTi-TEE (170 s) than for K3 (208 s).

CONCLUSIONS

Both systems maintained original canal curvature well and were safe to use. Whilst debridement of canals was considered satisfactory, both systems failed to remove smear layer sufficiently.

Influence of different types of automated devices on the shaping ability of rotary nickel-titanium FlexMaster instruments

AIM

To compare the shaping ability of rotary FlexMaster nickel-titanium instruments in simulated curved canals and in curved canals of extracted teeth when set into permanent rotation with three different torque-limited automated devices.

METHODOLOGY

Root canal instrumentation was performed with three different torque-limited automated devices (ENDOadvance, SIRONiTi and Endo IT motor) by FlexMaster nickel-titanium instruments up to size 35. Simulated canals: 28 degree and 35 degree curved canals in resin blocks (n = 20 canals in each group) were prepared. Pre- and post-instrumentation images were recorded and assessment of canal shape was completed with a computer image analysis program. Extracted teeth: A total of 60 curved root canals were divided into three groups, which were balanced with respect to the angle and the radius of canal curvature. Straightening of the canal curvatures was determined with a computer image analysis program. Incidence of canal aberrations, preparation time, changes of working length and instrument failures were recorded both in simulated and real canals.

RESULTS

In simulated and real canals, instrumentation with Endo IT was significantly faster than with SIRONiTi (P < 0.05). With respect to canal aberrations in simulated canals, there were no significant differences between the devices (P > 0.05), even though more aberrations were created with ENDOadvance and SIRONiTi. In real canals, the Endo IT motor resulted in significantly less straightening during instrumentation (P < 0.05) than SIRONiTi. A total of three instruments separated (one file in each group) during the enlargement of 35 degree curved simulated canals. All systems maintained working distance well.

CONCLUSIONS

All systems respected original root canal curvature well and were safe, indicating that torque-limited rotation handpieces are suitable for preparing curved root canals.

Comparison of root canal preparation using RaCe and ProTaper rotary Ni-Ti instruments

AIM

To compare various parameters of root canal preparation using RaCe (FKG Dentaire, La-Chaux-de-Fonds, Switzerland) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium (Ni-Ti) instruments.

METHODOLOGY

Fifty extracted mandibular molars with mesial root canal curvatures between 20 degrees and 40 degrees were embedded in a muffle system. All root canals were prepared to size 30 using RaCe or ProTaper rotary instruments in low-torque motors with torque control and constant speed of 300 r.p.m. (ProTaper with ATR Tecnika, Advanced Technology Research, Pistoia, Italy; RaCe with EndoStepper, S.E.T., Olching, Germany). In both groups irrigation was performed with 2 mL NaOCl (3%) after each instrument size. Calcinase-Slide (lege artis, Dettenhausen, Germany) was used as a chelating agent with each instrument. The following parameters were evaluated: straightening of curved root canals, postoperative root canal cross-sections, safety issues and working time. Cleanliness of the root canal walls was investigated under the SEM using 5-score indices for debris and smear layer. Statistical analysis was performed using the following tests: Wilcoxon's test for straightening and working time was used (P < 0.05); Fisher's exact test for comparison of cross-sections and root canal cleanliness (P < 0.05).

RESULTS

Both Ni-Ti systems maintained curvature well; the mean degree of straightening was less than 1 degrees for both systems. Following preparation with RaCe, 49% of the root canals had a round or oval diameter and 50% an irregular diameter, ProTaper preparations resulted in a round or oval diameter in 50% of the cases. For debris, RaCe and ProTaper achieved 47 and 49% scores of 1 and 2, respectively; there was no significant difference. For smear layer, RaCe and ProTaper achieved 51 and 33% scores 1 and 2, respectively; no statistically significant differences were apparent for the coronal and middle sections of the root canals, but RaCe performed significantly better in the apical region (Fisher's exact test, P = 0.0392). Two roots lost working length with RaCe instruments, whilst ProTaper preparation resulted in two roots loosing working length and one fractured instrument. Mean working time was shorter for ProTaper (90.9 s) than for RaCe (137.6 s); the difference was significant (Wilcoxon's test, P = 0.011).

CONCLUSIONS

Both systems respected original root canal curvature well and were safe to use. Cleanliness was not satisfactory for both systems.

The adoption of new endodontic technology amongst Danish general dental practitioners

AIM

To assess the adoption of new endodontic technology in a population of Danish practitioners.

METHODOLOGY

Members of the Copenhagen Dental Association (n = 1156) were approached with a questionnaire concerning the frequency of various endodontic procedures. Three options were available: often, occasionally and never. Responses were anonymous. The statistical analyses were performed as studies of association in two- or three-way contingency tables, and with Goodman-Kruskal's gamma-coefficient as the basic tool chosen.

RESULTS

Only data from general practitioners (GPs) in private practice were analysed (n = 956). The response rate was 72%. NiTi hand instruments were often used to negotiate canals by 18%, whilst 10% often used NiTi rotary systems. Electronic apex locators were often employed by 15%. Nineteen per cent reported that warm gutta-percha was often used. A majority (53%) often spend two sessions to instrument a molar, and 20% often needed three or more sessions to finish the shaping phase. To complete a treatment of a nonvital case most practitioners reported to use at least three appointments. Only 4% frequently applied rubber dam.

CONCLUSIONS

The adoption of new endodontic technology is at an early stage amongst Danish GPs. A new revised remuneration system might influence the rate of adoption, allowing the practitioners to act more rationally and produce a higher frequency of good-quality root fillings. Progress towards high quality endodontics might be hindered by the nonuse of rubber dam.

SEM evaluation of canal wall dentine following use of Mtwo and ProTaper NiTi rotary instruments

AIM

To compare using scanning electron microscopy (SEM) root canal walls following instrumentation in vitro with two different rotary NiTi instruments. The hypothesis was that no difference should be observable between the experimental groups in terms of debris on canal walls and surface morphology.

METHODOLOGY

Twenty-four single-rooted human teeth were selected. Two types of NiTi instruments were used, Mtwo (Sweden & Martina, Padova, Italy) and ProTaper (Dentsply Maillefer, Ballaigues, Switzerland). Irrigation for both groups was performed after each instrument change with 5% NaOCl, 3% H2O2 and 17% EDTA solutions. Three different areas (coronal, middle and apical thirds) of the root canal were evaluated using SEM. The canal wall of each sample was assessed and compared using a predefined scale of four parameters, namely, smear layer, pulpal debris, inorganic dentine debris, surface profile. Data were analysed statistically using the Kruskal-Wallis test (anova).

RESULTS

A statistically significant difference (P < 0.01) was found between the apical third and the middle and coronal thirds for both groups. No difference was observable between instrumentation groups. In the apical third canal walls were often contaminated by inorganic debris and by smear layer. In the apical third, the surface profile was affected by uninstrumented regions, comprising dentine depressions and grooves in which predentine was still visible.

CONCLUSION

Both instruments produced a clean and debris-free dentine surfaces in the coronal and middle thirds, but were unable to produce a dentine surfaces free from smear layer and debris in the apical third. The presence of deep grooves and depression on dentine walls in the apical third may well explain the presence of less-instrumented areas.