Publications by authors named "Michael Hülsmann"

19 Publications

  • Page 1 of 1

Remote Teaching in a Preclinical Phantom Course in Operative Dentistry During the COVID-19 Pandemic: Observational Case Study.

JMIR Med Educ 2021 May 14;7(2):e25506. Epub 2021 May 14.

Department of Preventive Dentistry, Periodontology and Cariology, University Medical Center Göttingen, Göttingen, Germany.

Background: During the acute COVID-19 pandemic, physical access to the University Medical Center Göttingen was restricted for students. For the first time at our dental school, theoretical knowledge was imparted to students via asynchronous online screencasts and discussed via synchronous video meetings only.

Objective: We aimed to assess the acceptance and effectiveness of distance education as a new teaching format for theoretical knowledge within the preclinical course in Operative Dentistry (sixth semester of the undergraduate dental curriculum in Germany).

Methods: The phantom course comprised distance education (first phase, 11 weeks) and subsequent on-site practical demonstrations and training (second phase, 10 weeks). All theoretical knowledge was taught via online screencasts during distance education (except for the first week, 3 screencasts were uploaded per week resulting in a total of 30 screencasts). Until the end of the term, all students (N=33) were able to view the screencasts for an unlimited number of times. Theoretical knowledge was assessed in a summative examination after practical on-site teaching. Acceptance and effectiveness of the new curriculum and distance education were also measured based on an evaluation survey and students' self-perceived learning outcome, which was compared to the outcome from the two pre-COVID-19 terms.

Results: Each screencast was viewed by a mean of 24 (SD 3.3) students and accessed a mean of 5.6 (SD 1.2) times per user (ie, by students who accessed the respective screencast at least once). During distance education, the number of accesses showed a linear trend over time. During the practical training phase, screencast views declined and increased again prior to the examination. Screencasts covering topics in Cariology, Restorative Dentistry, and Preventive Dentistry were viewed by more students than screencasts covering topics in Endodontology or Periodontology (both P=.047). Examination items in Periodontology showed inferior results compared to the other topics (P<.001). Within the different topics, students' self-perceived learning outcome did not differ from that during the pre-COVID-19 terms. Although most students agreed that the presented screencasts contributed to their learning outcome, pre-COVID-19 term students more strongly felt that lectures significantly contributed to their learning outcome (P=.03).

Conclusions: Screencasts showed high acceptance and effectiveness among the students but were not used as a learning tool by all students. However, students who viewed the screencasts accessed each screencast more frequently than they could have attended a conventional lecture. Screencast views were mostly due to intrinsic motivation.
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http://dx.doi.org/10.2196/25506DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8128048PMC
May 2021

Sensitivity of conventional radiographs and cone-beam computed tomography in detecting the remaining root-canal filling material.

J Oral Sci 2020 Jun 4;62(3):271-274. Epub 2020 Jun 4.

Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen.

This study aimed to compare the sensitivity of radiographs and flat-panel volume-computed tomography (fpVCT) in detecting the remaining root-canal filling material. Thirty-two root canals in extracted human mandibular molars were prepared and obturated with gutta-percha and sealer. The filling material was removed, and the teeth were split longitudinally. Radiographs and fpVCT scans were obtained and digitized. Virtual images were developed using reconstruction software and then superimposed, and the remaining filling material was outlined. Direct observation of the split root halves using flatbed scans served as a control. The presence and extension of the remaining filling material were evaluated. Statistical analysis was conducted using chi-squared test (P < 0.05). A total of 116 remnants were detected in the flatbed scans, 81 in the fpVCT scans, and 90 in the radiographs, with no significant difference between the radiograph (78%) and fpVCT (70%) results (P = 0.18). In the fpVCT scans, 42% of the remnants exhibited the same dimensions as the control, whereas 27% appeared larger and 30% appeared smaller. In the radiographs, the dimensions of the remnants were identical to the control in 64% of cases, smaller in 29%, and larger in 7%. FpVCT did not exhibit better performance than dental radiographs in detecting the remaining root-canal-filling material: the extension of remnants was indicated correctly in the fpVCT in fewer than 50% of the samples.
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http://dx.doi.org/10.2334/josnusd.19-0100DOI Listing
June 2020

Micro-computed Tomographic Evaluation of the Shaping Ability of 3 Reciprocating Single-File Nickel-Titanium Systems on Single- and Double-Curved Root Canals.

J Endod 2020 Aug 25;46(8):1130-1135. Epub 2020 May 25.

Department for Preventive Dentistry, Periodontology and Cariology, University Medical Center, Göttingen, Germany.

Introduction: We performed a micro-computed tomographic assessment of the preparation of moderately single- and double-curved root canals using 3 single-file reciprocating nickel-titanium systems: S1 Plus Standard (Sendoline, Täby, Sweden), WaveOne Gold Primary (Dentsply Sirona, Ballaigues, Switzerland), and Reciproc R25 (VDW, Munich, Germany).

Methods: Seventy-five moderately curved mandibular molars with 2 separate mesial root canals were assigned to 3 experimental groups (n = 25) (ie, S1 Plus Standard, WaveOne Gold Primary, and Reciproc 25 groups) by forming matched triples according to curvature (15°-40°), radius (≤18 mm), and type of curvature (single or double curved). Teeth were scanned before and after root canal preparation with a resolution of 10.5 μm using micro-computed tomographic imaging (Bruker SkyScan 1272; Bruker microCT, Kontich, Belgium). The following parameters were assessed: changes in root canal volume and surface area, percentage of unshaped canal walls, structure model index, canal transportation, and centering ratio. Data were analyzed using 2- and 3-way analysis of variance with Tukey and Scheffé post hoc tests (significance level of 5%).

Results: No significant differences among groups were observed concerning all parameters. The type of curvature had no significant effect on all tested parameters. Within all experimental groups, canal transportation increased significantly from the apical to the coronal region, of which the majority was directed toward the furcational area.

Conclusions: Preparation with the 3 nickel-titanium systems did not result in significantly different dimensional changes, and there was no significant effect of the type of curvature on all tested parameters.
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http://dx.doi.org/10.1016/j.joen.2020.05.005DOI Listing
August 2020

Cleanliness and erosion of root canal walls after irrigation with a new HEDP-based solution vs. traditional sodium hypochlorite followed by EDTA. A scanning electron microscope study.

Clin Oral Investig 2020 Oct 16;24(10):3699-3706. Epub 2020 May 16.

Department of Preventive Dentistry, Periodontology and Cariology, University of Goettingen, Goettingen, Germany.

Objectives: To compare the cleanliness and erosion of root canal walls after the use of a new HEDP (1-hydroxyethane-1,1-diphosphonic acid) -based irrigant with that achieved by irrigation with sodium hypochlorite followed by EDTA.

Materials And Methods: Forty recently extracted single-rooted teeth were prepared with ProTaper Next files to size X3, using either HEDP-containing 3% sodium hypochlorite, throughout the procedure (n = 20), or 3% sodium hypochlorite followed by a final rinse with 17% EDTA (n = 20), which were both applied with a syringe and needle. Ten additional teeth were prepared and irrigated with saline and served as negative controls. The teeth were split longitudinally and subjected to SEM evaluation for the presence of a smear layer, debris, and erosion of the root canal wall. The Pearson chi-square test was used to compare the results, and the level of significance was set at p < 0.05.

Results: In both groups, there were more cases with a smear layer in the apical third of the root canal than in the coronal third, but the groups did not differ from each other significantly (p = 0.545). The root canal walls in both groups were almost free of debris, showing no difference between the groups (p = 0.342). Moderate erosion of the root dentine was found in 10-26% of the cases in both groups, but severe erosion was detected in only one case in each of the groups, which did not differ significantly from each other (p = 0.606).

Conclusion: Within the limitations of the present study, the HEDP-based irrigation solution did not differ from 3% sodium hypochlorite followed by EDTA in terms of cleanliness or the incidence of erosion of the canal wall.

Clinical Relevance: When used with syringe and needle irrigation, the new HEDP-based irrigant is convenient and safe but should not be expected to result in cleaner canal walls than 3% sodium hypochlorite followed by 17% EDTA.
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http://dx.doi.org/10.1007/s00784-020-03249-wDOI Listing
October 2020

Cone-beam-computed-tomography of the symmetry of root canal anatomy in mandibular incisors.

J Oral Sci 2020 ;62(2):180-183

Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen.

This study aimed to evaluate the prevalence of internal symmetry (the number and morphology of root canals) in the mandibular incisors using cone beam computed tomography (CBCT). A total of 302 CBCT scans involving 1,208 mandibular incisors were evaluated using the Vertucci's classification regarding the number and configuration of root canals. The central mandibular incisors exhibited two root canals in 22.6% of patients and lateral incisors in 24.3% of patients. Most teeth (76.4%) had a type I configuration (a single root canal, 1-1), 21.7% had type II (2-1), 1.1% had type V (1-2), and 0.8% had type IV (2-2). Teeth with a type-III configuration (1-2-1) were not found. In total, 17.5% of patients had a symmetric appearance of the two-canalled central mandibular incisors and 20.5% had a bilateral appearance of the two-canal lateral incisors. Moreover, in 12.3% of the patients, all four incisors showed two root canals. The highest degree of symmetry was found in incisors that had one root canal (central incisors: 217 of 302, lateral incisors: 229 of 302), followed by type 2-1 incisors (central incisors 50, lateral incisors 58). The influence of sex and age on the prevalence of symmetries was not significant. Concluding, the internal anatomy of the mandibular incisors cannot not be sufficiently predicted from the root canal anatomy of the contralateral tooth. Thorough clinical and radiographic inspection of each tooth remains mandatory to address the internal anatomy of the mandibular incisors correctly.
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http://dx.doi.org/10.2334/josnusd.19-0113DOI Listing
April 2020

Research that matters: studies on fatigue of rotary and reciprocating NiTi root canal instruments.

Int Endod J 2019 Oct;52(10):1401-1402

Department of Preventive Dentistry, Periodontology and Cariology, University Medicine Göttingen (UMG), Göttingen, Germany.

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http://dx.doi.org/10.1111/iej.13194DOI Listing
October 2019

Root canal preparation using S5, Mtwo, and ProTaper Universal nickel-titanium systems: a comparative ex-vivo study.

Quintessence Int 2019 ;50(5):358-368

Objectives: To examine various parameters of root canal preparation using three rotary nickel-titanium systems (S5, Mtwo, and ProTaper Universal [PTU]).

Method And Materials: One hundred and twenty curved root canals were prepared to size 30. The following parameters were evaluated: straightening, changes of root canal cross-section, safety issues, cleanliness of canal walls, and working time. Statistical analysis was performed with the Kruskal-Wallis test, Wilcoxon-Mann-Whitney test, and analysis of variance (P < .050).

Results: All three systems maintained the curvature well with no significant difference between the groups. With regard to the cross-section, no significant differences for any of the root canal thirds (coronal, P = .589; medial, P = .898; apical, P = .474) were found. Preparation with S5 resulted in two, with Mtwo in one, and with PTU in three procedural incidents. Debris scores 1 and 2 were found in 56% (S5), 46% (Mtwo), and 60% (PTU) of the specimens, respectively. Smear layer scores 1 and 2 were found in 85% (S5), 73% (Mtwo), and 78% (PTU). Results for removal of debris and smear layer were not significantly different between the three groups. Mean working time was significantly shorter for Mtwo (293 seconds) than for S5 (329 seconds) (P = .001) or PTU (369 seconds) (P = .001).

Conclusion: All three systems respected the original root canal curvature well and were safe to use. None of the three systems was able to prepare the entire circumference of the root canals, and to remove debris and smear layer completely.
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http://dx.doi.org/10.3290/j.qi.a42326DOI Listing
November 2019

Effectiveness of different activated irrigation techniques on debris and smear layer removal from curved root canals: a SEM evaluation.

Aust Endod J 2020 Apr 25;46(1):40-46. Epub 2019 Mar 25.

Department of Preventive Dentistry, Periodontology and Cariology, University Medical Center Göttingen, Göttingen, Germany.

This study evaluates the effectiveness of different activated irrigation techniques on removal of debris and smear layer from curved root canals. Ninety mandibular molars with a root canal curvature between 20 and 40 degrees were assigned to 4 groups (n = 20): syringe irrigation (SI), passive ultrasonic activation (PUI), sonic activation with EDDY (ED) or EndoActivator (EA) and a control group. Mesiobuccal root canals were prepared to size 40, 0.04 and irrigated with NaOCl (3%) according to the respective technique. Roots were split longitudinally and subjected to scanning electron microscopic analysis. Presence of debris and smear layer was evaluated using 5-grade scoring systems with 200× and 1000× magnification, respectively. Data were analysed with nonparametric analysis for ordinal longitudinal data (α = 5%). Activation of the irrigant significantly improved smear layer removal (P < 0.05). Regarding debris, only activation with EA and ED was significantly more effective than SI (P < 0.05). No activation technique was able to eliminate debris and smear layer completely from curved root canals.
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http://dx.doi.org/10.1111/aej.12342DOI Listing
April 2020

A comparative in vitro study of different techniques for removal of fibre posts from root canals.

Aust Endod J 2018 Dec 20;44(3):245-250. Epub 2017 Sep 20.

Department of Preventive Dentistry, Periodontology and Cariology, University Medical Center Göttingen, Göttingen, Germany.

This study evaluates the effectiveness of different techniques to remove fibre posts from root filled teeth in vitro. One hundred and fifty-three extracted single-rooted teeth were decoronated, root-canal treated and divided into three groups (n = 51). Post spaces were prepared for different types of fibre posts: glass fibre, quartz fibre, carbon fibre. Each group was divided into three subgroups with regard to the post removal technique (n = 17): SonicFlex Endo, long-shaft round bur, DT-Post removal kit. Residual material, loss of dentine, working time and procedural errors were assessed using computed tomography. Statistical analysis was performed with a one-way anova (α = 0.05). The highest effectiveness was achieved with the sonic tip and the round bur. A high prevalence of perforations or severe deviations from the root axis was observed for all groups. No technique presented favourable results in all assessed parameters. There is a high risk of perforations.
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http://dx.doi.org/10.1111/aej.12230DOI Listing
December 2018

Comparison of different techniques for removal of calcium hydroxide from straight root canals: an in vitro study.

Odontology 2017 Oct 15;105(4):453-459. Epub 2017 Mar 15.

Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen, Robert-Koch-Str. 40, 37075, Göttingen, Germany.

To compare four different techniques for removal of calcium hydroxide from straight root canals. The present study used the design suggested by Lee et al. (Int Endod J 37:607-612, 32) and van der Sluis et al. (Int Endod J 40:52-57, 17). One-hundred and ten extracted human teeth with straight root canals were prepared to ISO-size 50 and split longitudinally. Two lateral grooves were prepared, filled with calcium hydroxide and the root halves reassembled in a muffle. Calcium hydroxide was removed using one of five techniques: (1) passive ultrasonic irrigation, (2) hydrodynamic irrigation using RinsEndo, (3) sonic irrigation using the EndoActivator, (4) motor-driven plastic brush (CanalBrush™), and (5) manual irrigation with a syringe as the control group. Distilled water was used as irrigant. Cleanliness of the grooves was scored under a microscope with 40× magnification. For intraindividual reproducibility and interrater agreement, Cohens Kappa was calculated. Results of scoring were analyzed using a non-parametric test. Post hoc pairwise comparisons were used for irrigation techniques (α = 0.05). Passive ultrasonic irrigation performed significantly better than all other groups in the apical groove. Significant differences were found between RinsEndo and CanalBrush (P = 0.01855) and CanalBrush and syringe irrigation (P = 0.00021). In the coronal groove, passive ultrasonic irrigation performed significantly superior and hand irrigation performed significantly worse than all other groups. A statistically significant interaction was shown between irrigation technique and localization of the groove (P = 0.01358). The coronal grooves showed more remaining calcium hydroxide than the apical grooves. Complete removal of calcium hydroxide from the root canal could not be achieved with any of the techniques investigated. The highest degree of cleanliness resulted from the use of passive ultrasonic irrigation.
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http://dx.doi.org/10.1007/s10266-017-0293-6DOI Listing
October 2017

Nerve regeneration techniques respecting the special characteristics of the inferior alveolar nerve.

J Craniomaxillofac Surg 2016 Sep 2;44(9):1381-6. Epub 2016 Jul 2.

Department of Oral and Maxillofacial Surgery, Schleswig-Holstein University Hospital, Arnold-Heller-Straße 3, Haus 26, 24105 Kiel, Germany.

Purpose: The aim of this study was to examine the in situ regeneration of the inferior alveolar nerve (IAN) in its bony channel, using autologous tissue in combination with a recombinant human nerve growth factor (rhNGF).

Materials And Methods: A total of 20 New Zealand rabbits were randomly divided into five groups. Following dissection of the IAN, the animals underwent reconstruction either with muscle tissue (groups 1 and 2) or with fat tissue (groups 3 and 4). In group 5 (control), the dissected nerve was resected and reconstructed by placement of the reversed autologous segment. After 2 and 4 weeks, 1 mL rhNGF was locally injected in groups 1 and 3. Nerve function was monitored by measuring the jaw-opening reflex using electromyography for a period of 24 weeks.

Results: Regeneration of the nerve was achieved in all groups, but preoperative threshold values were not achieved. Comparing the experimental groups to the control, there was a significant difference in favor of the autologous nerve reconstruction. Differences between the experimental groups remained statistically not significant.

Conclusion: Regeneration of the IAN with autologous tissue is possible, but without achieving preoperative thresholds. Additional injection of a growth factor seems to improve the speed of regeneration for fat and muscle grafts.
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http://dx.doi.org/10.1016/j.jcms.2016.06.020DOI Listing
September 2016

Treatment outcome after repair of root perforations with mineral trioxide aggregate: a retrospective evaluation of 90 teeth.

J Endod 2013 Nov 5;39(11):1364-8. Epub 2013 Sep 5.

Praxis Dr. Bargholz and Partner, Private Practice for Endodontics, Hamburg, Germany. Electronic address:

Introduction: In this retrospective study, the success rate for the repair of root perforations using mineral trioxide aggregate was investigated.

Methods: One hundred forty consecutive cases of teeth with perforations were included in the sample; 128 finally met the inclusion criteria. All treatments were performed between 1999 and 2009 in a dental office limited to endodontics. Perforations were sealed with mineral trioxide aggregate using a dental operating microscope. Treatment success was assessed by analyzing clinical data and radiographs 1-10 years after treatment. The radiographs were evaluated by 2 independent calibrated examiners. The outcome measure was dichotomized as "healed" or "failure." The relationship between preoperative data and treatment outcome was examined to determine potential prognostic factors.

Results: From 128 teeth, 90 were accessible for recall (70.3%). The mean follow-up interval was 3.4 years. Sixty-six teeth (73.3%) were classified as healed. A significant relationship between treatment success and the presence of a preoperative lesion at the perforation site was found. Those teeth in which a lesion at the perforation site was present before treatment showed a lower healing rate. Teeth with a preoperative communication between the perforation and the oral cavity showed the lowest success rate.

Conclusions: Two prognostic factors for healing of teeth with perforations were identified. The presence of a preoperative lesion at the perforation site and direct contact between the perforation and the oral cavity were related to lower treatment success rates.
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http://dx.doi.org/10.1016/j.joen.2013.06.030DOI Listing
November 2013

Comparison of ultrasonic irrigation and RinsEndo for the removal of calcium hydroxide and Ledermix paste from root canals.

Int Endod J 2011 Dec 13;44(12):1155-61. Epub 2011 Sep 13.

Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen, Göttingen, Germany.

Aim: To compare the efficacy of ultrasonic irrigation and RinsEndo in removing calcium hydroxide and Ledermix paste from simulated root canal irregularities.

Methodology: The root canals of sixty extracted single-rooted teeth were prepared using FlexMaster rotary instruments to size 60, 0.02 taper. The roots were split longitudinally, and a standardized groove was prepared in the apical part of one segment. The teeth were randomly allocated into two groups (n = 30), according to the intracanal dressing. In the first group, grooves were filled with calcium hydroxide paste (Calxyl), whereas the grooves in the second group were filled with Ledermix paste. After reassembly, the root canals were completely filled with the respective medicament using a lentulo. The removal of medicament dressing was performed after 7 days with either passive ultrasonic irrigation or RinsEndo and 1% sodium hypochlorite for 3 min. The amount of remaining medicament was evaluated under a microscope with 30 × magnification using a four-grade scoring system. A regression analysis with P ≤ 0.05 was performed.

Results: Ledermix paste removal was significantly more effective than the removal of calcium hydroxide (P < 0.0001), whereas irrigation technique was not a significant factor (P = 0.3712). The percentages of complete removal of calcium hydroxide and Ledermix paste were 11.7% and 51.7%, respectively.

Conclusions: None of the irrigation techniques was able to completely remove the intracanal medicaments from the apical part of the root canal. Irrespective of the irrigation technique, significantly less Ledermix paste was detected compared with calcium hydroxide.
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http://dx.doi.org/10.1111/j.1365-2591.2011.01937.xDOI Listing
December 2011

Comparison of root canal preparation using reciprocating Safesiders stainless steel and Vortex nickel-titanium instruments.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011 May 16;111(5):659-67. Epub 2011 Mar 16.

Department of Endodontics, University of Alabama School of Dentistry, Birmingham, Alabama, USA.

Objective: The aim of the present study was to assess several parameters related to the clinical usage of 2 root canal preparation instruments: Vortex .06 rotary nickel-titanium instruments, and Safesiders reciprocating stainless steel instruments.

Study Design: Fifty extracted mandibular molars with mesial root canal curvatures between 20° and 50° were divided into 2 groups and embedded in acrylic resin inside a modified Bramante muffle system. All root canals were prepared to ISO size 40 using either Vortex .06 rotary nickel-titanium-instruments in a low-torque motor or Safesiders stainless steel instruments in a proprietary reciprocating handpiece. The following parameters were evaluated: straightening of curved root canals, working safety issues (perforations, instrument breakages, canal blockages, loss of working length), postpreparation root canal cross-section, and working time.

Results: The Vortex .06 instruments maintained canal curvatures well, with the mean degree of straightening recorded as 0.72°. Safesiders instruments demonstrated significantly more canal straightening, with the mean degree of straightening recorded as 15.5°. More than 90% of the root canals prepared with the Vortex .06 instruments resulted in a round or oval cross-section, whereas the Safesiders instruments produced round or oval cross-sections 60% of the time. Neither of the 2 instruments could effectively prepare 100% of the root canal circumference. The area of dentin removed and the remaining dentin thicknesses from each region were similar for the 2 groups. Six procedural incidents were recorded for the Vortex .06 group, compared with 19 for the Safesiders group. There were no instrument fractures recorded in either group. Mean working time was significantly shorter for Vortex .06 (279 s) than for Safesiders (324 s).

Conclusions: Vortex .06 maintained the original root canal curvatures well, whereas Safesiders instruments demonstrated significant straightening and irregular preparation shapes when used in sizes larger than ISO 20. Preparation of the complete circumference of the root canal was not possible with either system. Fewer procedural errors occurred with the Vortex instruments.
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http://dx.doi.org/10.1016/j.tripleo.2010.11.021DOI Listing
May 2011

Comparison of root canal preparation using Flex Master Ni-Ti and Endo-Eze AET stainless steel instruments.

Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2011 Feb 16;111(2):251-9. Epub 2010 Dec 16.

Department of Preventive Dentistry, University of Göttingen, Göttingen, Germany.

Objective: The aim of this study was to compare various parameters of root canal preparation using FlexMaster rotary nickel-titanium and Endo-Eze AET stainless steel instruments.

Study Design: Fifty curved mesial root canals of extracted mandibular molars were prepared to size 45 using FlexMaster or AET instruments. The following parameters were evaluated: straightening of root canal curvature, postoperative root canal cross-sections, cleaning ability, safety issues, and working time. Statistical analyses were performed using Mann-Whitney U test and Wilcoxon test.

Results: The mean degree of straightening was significantly less for FlexMaster than for AET (P = .001). Postoperative cross-sections showed no significant differences between the systems. Neither of the systems completely eliminated debris and smear layer. No procedural incidents occurred with the instruments. Mean working time was significantly shorter for FlexMaster than for AET (P = .0001).

Conclusions: AET cannot be recommended for preparation of curved root canals, owing to unacceptable straightening.
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http://dx.doi.org/10.1016/j.tripleo.2010.08.022DOI Listing
February 2011

Effectiveness of different irrigant agitation techniques on debris and smear layer removal in curved root canals: a scanning electron microscopy study.

J Endod 2010 Dec 18;36(12):1983-7. Epub 2010 Oct 18.

Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen, Göttingen, Germany.

Introduction: The aim of this study was to evaluate the cleaning efficacy of different irrigant agitation techniques on debris and smear layer removal in curved root canals.

Methods: Mesiobuccal root canals of 108 mandibular molars were shaped with nickel-titanium instruments, and a final rinse of NaOCl and ethylenediaminetetraacetic acid was performed. Specimens were assigned to 4 groups (n = 20) and submitted to the following irrigation agitation techniques: no agitation (control), ultrasonic, EndoActivator, and CanalBrush. Root canals were split longitudinally and subjected to scanning electron microscopy. The presence of debris and smear layer at coronal and apical levels was evaluated by using a 5-grade scoring system with 200× and 1000× magnification, respectively.

Results: Concerning debris removal, no significant differences among groups were detected. In the coronal region, agitation of the irrigants resulted in significantly more smear layer removal than the control. EndoActivator was significantly more effective than ultrasonic agitation and CanalBrush.

Conclusions: In curved root canals, activation of NaOCl and ethylenediaminetetraacetic acid did not enhance debris removal but resulted in significantly more effective smear layer removal at coronal levels.
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http://dx.doi.org/10.1016/j.joen.2010.08.056DOI Listing
December 2010

Comparison of the Vibringe system with syringe and passive ultrasonic irrigation in removing debris from simulated root canal irregularities.

J Endod 2010 Aug 25;36(8):1410-3. Epub 2010 Jun 25.

Department of Preventive Dentistry, Periodontology and Cariology, University of Göttingen, 37075 Göttingen, Germany.

Introduction: The aim of this study was to compare the efficiency of a sonic device (Vibringe), syringe irrigation, and passive ultrasonic irrigation in the removal of debris from simulated root canal irregularities.

Methods: Root canals with 2 standardized grooves in the apical and coronal parts were filled with dentin debris. Three different irrigation procedures were performed with NaOCl (1%) and (1) syringe irrigation, (2) Vibringe, and (3) passive ultrasonic irrigation. The amount of remaining debris was evaluated by using a 4-grade scoring system.

Results: Ultrasonic irrigation removed debris significantly better from the artificial canal irregularities than the Vibringe System and syringe irrigation (P < .0001). The Vibringe System demonstrated significantly better results than syringe irrigation in the apical part of the root canal (P = .011).

Conclusions: Passive ultrasonic irrigation is more effective than the Vibringe System or syringe irrigation in removing debris. The sonic device demonstrated significantly better results than syringe irrigation in the apical root canal third.
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http://dx.doi.org/10.1016/j.joen.2010.04.023DOI Listing
August 2010

The self-adjusting file (SAF). Part 3: removal of debris and smear layer-A scanning electron microscope study.

J Endod 2010 Apr;36(4):697-702

Department of Endodontology, The Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, Israel.

Aim: The aim of this study was to evaluate the cleaning ability of the Self-Adjusting File (SAF) system in terms of removal of debris and smear layer.

Methodology: Root canal preparations were performed in 20 root canals using an SAF operated with a continuous irrigation device. The glide path was initially established using a size 20 K-file followed by the SAF file that was operated in the root canal via a vibrating motion for a total of 4 minutes. Sodium hypochlorite (3%) and EDTA (17%) were used as continuous irrigants and were alternated every minute during this initial 4-minute period. This was followed by a 30-second rinse using EDTA applied through a nonactivated SAF and a final flush with sodium hypochlorite. The roots were split longitudinally and subjected to scanning electron microscopy (SEM). The presence of debris and a smear layer in the coronal, middle, and apical thirds of the canal were evaluated through the analysis of the SEM images using five-score evaluation systems based on reference photographs.

Results: The SAF operation with continuous irrigation, using alternating irrigants, resulted in root canal walls that were free of debris in all thirds of the canal in all (100%) of the samples. In addition, smear layer-free surfaces were observed in 100% and 80% of the coronal and middle thirds of the canal, respectively. In the apical third of the canal, smear layer-free surfaces were found in 65% of the root canals.

Conclusions: The operation of the SAF system with continuous irrigation coupled with alternating sodium hypochlorite and EDTA treatment resulted in a clean and mostly smear layer-free dentinal surface in all parts of the root canal.
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http://dx.doi.org/10.1016/j.joen.2009.12.037DOI Listing
April 2010

Microorganisms in root canal-treated teeth from a German population.

J Endod 2008 Aug;34(8):926-31

Department of Endodontics, Estácio de Sá University, Rio de Janeiro, Brazil; Department of Molecular Microbiology, Estácio de Sá University, Rio de Janeiro, Brazil.

Posttreatment apical periodontitis is usually associated with persistent or secondary intraradicular infection. This study evaluated the presence and relative levels of 28 bacterial taxa in treated root canals of teeth with posttreatment apical periodontitis from German patients using 16S ribosomal RNA (rRNA) gene probes in a reverse-capture checkerboard hybridization assay. Species-specific polymerase chain reaction (PCR) was also performed to detect Enterococcus faecalis and Candida albicans. Bacterial DNA was detected in all samples. Twenty of the 28 taxon-specific probes tested were reactive with at least one sample. Taxa detected more frequently included Streptococcus species (47%), Lactobacillus species (35%), Dialister invisus (29%), Eubacterium infirmum (29%), Prevotella intermedia (29%), Selenomonas sputigena (29%), Synergistes oral clone BA121 (29%), and Treponema denticola (29%). Only eight taxa were present at levels >10(5). Of these, streptococci and T. denticola were the most prevalent. Species-specific PCR detected E. faecalis in 47% of the cases and C. albicans in 6%. Findings of this study confirm the strong association between persistent/secondary intraradicular infection and posttreatment apical periodontitis. Most cases harbored a mixed infection, and E. faecalis, if present, was never the most dominant species in the consortium. Several other bacterial taxa were detected, and an involvement with the etiology of posttreatment apical periodontitis is suspected.
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http://dx.doi.org/10.1016/j.joen.2008.05.008DOI Listing
August 2008