Precision-milled simulated curved root canals in bovine dentine for the assessment of chemo-mechanical root canal preparation.

AIM: The aim was to develop a standardized curved root canal model in bovine dentine and to assess whether that natural substrate would behave differently from the resin in standard plastic training blocks when prepared chemo-mechanically. The impact of substrate microhardness on simulated canal transportation was considered. METHODOLOGY: High-precision computer numerical control (CNC) milling was used to recreate a simulated root canal from a resin training block (Endo Training Bloc J-Shape, size 15) in longitudinally sectioned, dis- and re-assembled bovine incisor roots. Optical overlays obtained from 10 resin blocks were used to identify an average canal and program the CNC milling apparatus accordingly. Resin and dentine microhardness were measured. Simulated root canals in resin training blocks and their bovine counterparts were then instrumented at 37°C using Reciproc R25 instruments (VDW) with water or 17% EDTA (n = 10). Open-access image processing software was used to superimpose and analyse pre- and postoperative images obtained with a digital microscope. Centering ratios were averaged to indicate canal transportation. The effects of substrate and irrigant on canal transportation were assessed by two-way anova. RESULTS: Superimposed images showed that resin blocks under investigation varied considerably in terms of simulated canal length and curvature, whilst the milled canals were highly similar. The microhardness of dentine was more than three times higher than that of the resin. Conversely, canal transportation was considerably greater in dentine compared to resin, and in dentine had a tendency to be increased by EDTA. There was a strong effect of substrate on canal transportation (p < .001), no overall effect of irrigant, and a marginally significant interaction between irrigant and substrate (p = .077). CONCLUSIONS: CNC milling allows to create standardized simulated curved root canals in bovine dentine. These models may be useful to test and compare materials and concepts of chemo-mechanical root canal instrumentation. Microhardness is a bulk feature that does not predict the response to chemo-mechanical instrumentation of a composite material such as dentine.

Removal of Thermafil Obturators Using 2 Different Techniques: A Comparative Ex Vivo Study.

INTRODUCTION: The aim of this ex vivo study was to compare 2 techniques for removal of Thermafil obturators from curved root canals in mandibular molars. METHODS: Sixty mesial root canals in extracted mandibular molars were distributed into matched pairs according to degree and radius of curvature and were prepared to size 35/.04 and obturated with Thermafil obturators size 35. Each tooth was embedded in resin, mounted in a mannequin head, and isolated with rubber dam to simulate clinical conditions. Removal of obturators was undertaken under a dental operating microscope by an experienced endodontist using either the FragRemover loop device, or reciprocating NiTi instruments. Pre- and postoperative micro-CT scans were taken to compare the amount of remaining filling material and of removed dentin. Eventual problems during removal attempts were recorded. RESULTS: Using Reciproc, 24 carriers (80%) were removed, 16 in one piece, 8 in small pieces, and in 6 cases removal failed. The FragRemover removed 12 carriers (40%), all of these completely, but in 18 cases removal failed (P < .05). Reciproc left less remaining filling material than the FragRemover (P < .05) but removed significantly more dentin in the apical part of the root canal (P < .01). There was no significant difference concerning the total amount of removed dentin (P > .05) between both groups. Seven complications occurred in the Reciproc group. In 5 teeth, working length could not be reached; in 2 teeth, a Reciproc file R25 fractured. With the FragRemover, 64 complications occurred, in 36 cases, including second removal attempts, the loop slipped over the carrier, in 24 cases the top of the carrier was sheared off. In 9 cases, separation of the core occurred too far apically, not allowing further use of the FragRemover. In 4 cases, the wire loop tore. CONCLUSIONS: Reciproc was more effective in removal of Thermafil carriers, whereas when using the FragRemover less dentin was removed in the apical part of the root canal and more obturation material was left.

Three Visual-Diagnostic Methods for the Detection of Enamel Cracks: An In Vitro Study.

Tooth fractures are a common cause of tooth loss, frequently starting as enamel cracks. However, methods for the detection of enamel cracks are poorly investigated. The aim of the study was the validation of three clinical methods for the detection of enamel cracks: dental operating microscope (DOM), near-infrared transillumination (NIR), and fiber-optic transillumination (FOTI), with hard-tissue slices serving as controls. A total of 89 extracted teeth, set up as diagnostic models, were investigated, and the maximum crack depth was scored by two examiners. The actual crack depth was determined microscopically (25×) using horizontal sections. The accuracy of each method was analyzed using receiver operating characteristic (ROC) curves. Across all tooth surfaces, the area under the curve (AUC) amounted to 0.57 (DOM), 0.70 (FOTI), and 0.67 (NIR). For crack detection on vestibular/oral surfaces, the AUC was 0.61 (DOM), 0.78 (FOTI), and 0.74 (NIR); for proximal surfaces, it was 0.59 (DOM), 0.65 (FOTI), and 0.67 (NIR). However, the actual crack depth was underestimated with each method (p < 0.001). Under in vitro conditions, FOTI and NIR are suitable for detection of enamel cracks, especially on vestibular and oral tooth surfaces. However, an exact estimation of crack depth is not possible. Therefore, FOTI and NIR seem to be helpful for the clinical detection of enamel cracks.

A critical appraisal of research methods and experimental models for studies on root canal preparation.

It is the aim of this review to present a critical overview and summary on the contemporary possibilities, limitations and challenges of research related to root canal preparation. Frequently used research tools and contemporary research designs will be presented and discussed critically focussing on shortcomings and benefits with special regard to clinical relevance and scientific evidence. A plethora of experimental set-ups for assessing the shaping of root canals have been described in the endodontic literature using a considerable number of techniques and instruments. Nevertheless, it can be stated that scientific evidence demonstrating the clinical impact of many investigated topics is questionable or even missing. Instead of technical, radiographic and geometrical parameters, further research should focus on biological aspects and clinical evidence of the impact of root canal preparation on the outcome of root canal treatment.

Energy-Dispersive X-Ray Spectrometry Analysis and Radiopacity of Five Different Root Canal Sealers.

Root canal sealers should have optimum adhesion to the root dentin, low cytotoxicity, sufficient radiopacity and high dimensional stability, which depend mainly on their chemical composition. The aims of this study were to evaluate the chemical composition of Syntex (Cerkamed, Stalowa Wola, Poland), Adseal (Meta Biomed, Cheongju-si, Korea), Sealapex (SybronEndo, Scafati, Italy), MTA Fillapex (Angelus, Londrina, Brazil) and GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Switzerland) and to determine their radiopacity comparatively. Stainless steel molds with an inner diameter of 5 mm and a depth of 2 mm were constructed. Tested root-canal sealers were mixed and poured into the molds. Following setting, digital periapical radiographs of the specimens (n=12) were taken under standard exposure conditions and the mean gray-values of specimens were measured using a computer graphics program. Then the specimens were examined by scanning electron microscopy, and Energy-dispersive X-ray analysis was performed. The data were analyzed using One-way ANOVA followed by Holm-Sidak multi-comparison test (p = 0.05). Sealapex showed higher calcium peak than MTA Fillapex, GuttaFlow Bioseal, Adseal and Syntex sealers. MTA Fillapex contained a highest amount of tungstate. Sealapex presented the highest radiopacity value among the tested materials (p < 0.05), whereas MTA Fillapex was the least radiopaque material (p < 0.05). Each root canal sealer contains different compositions of radiopacifiers including bismuth oxide, calcium tungstate and zirconium oxide. The tested root canal sealers had radiopacity values above the ISO-specified limit. Sealapex was the most radiopaque root canal sealer followed by GuttaFlow Bioseal, Syntex, Adseal and MTA Fillapex.

Energy-Dispersive X-Ray Spectrometry Analysis and Radiopacity of Five Different Root Canal Sealers

Abstract Root canal sealers should have optimum adhesion to the root dentin, low cytotoxicity, sufficient radiopacity and high dimensional stability, which depend mainly on their chemical composition. The aims of this study were to evaluate the chemical composition of Syntex (Cerkamed, Stalowa Wola, Poland), Adseal (Meta Biomed, Cheongju-si, Korea), Sealapex (SybronEndo, Scafati, Italy), MTA Fillapex (Angelus, Londrina, Brazil) and GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Switzerland) and to determine their radiopacity comparatively. Stainless steel molds with an inner diameter of 5 mm and a depth of 2 mm were constructed. Tested root-canal sealers were mixed and poured into the molds. Following setting, digital periapical radiographs of the specimens (n=12) were taken under standard exposure conditions and the mean gray-values of specimens were measured using a computer graphics program. Then the specimens were examined by scanning electron microscopy, and Energy-dispersive X-ray analysis was performed. The data were analyzed using One-way ANOVA followed by Holm-Sidak multi-comparison test (p = 0.05). Sealapex showed higher calcium peak than MTA Fillapex, GuttaFlow Bioseal, Adseal and Syntex sealers. MTA Fillapex contained a highest amount of tungstate. Sealapex presented the highest radiopacity value among the tested materials (p < 0.05), whereas MTA Fillapex was the least radiopaque material (p < 0.05). Each root canal sealer contains different compositions of radiopacifiers including bismuth oxide, calcium tungstate and zirconium oxide. The tested root canal sealers had radiopacity values above the ISO-specified limit. Sealapex was the most radiopaque root canal sealer followed by GuttaFlow Bioseal, Syntex, Adseal and MTA Fillapex.

Resumo Os cimentos endodônticos devem conter ótima adesão à dentina radicular, baixa citotoxicidade, radiopacidade suficiente e estabilidade dimensional elevada, que dependem principalmente da sua composição química. Os objetivos deste estudo foram avaliar a composição química de Syntex (Cerkamed, Stalowa Wola, Polônia), Adseal (Meta Biomed, Cheongju-si, Coreia), Sealapex (SybronEndo, Scafati, Itália), MTA Fillapex (Angelus, Londrina, Brasil) e GuttaFlow Bioseal (Coltene/Whaledent, Altstätten, Suíça) e determinar comparativamente a sua radiopacidade. Foram construídos moldes de aço inoxidável com um diâmetro interior de 5 mm e uma profundidade de 2 mm. Os cimentos testados foram misturados e vertidos em moldes. Após a fixação, foram feitas radiografias periapicais digitais dos espécimes (n=12) em condições de exposição padrão e os valores médios de cinza dos espécimes foram medidos utilizando um programa de computação gráfica. Em seguida, as amostras foram examinadas por microscopia eletrônica de varredura, e foi realizada uma análise de raios X dispersiva de energia. Os dados foram analisados utilizando a ANOVA unidirecional seguida do teste de comparação múltipla Holm-Sidak (p = 0,05). O Sealapex mostrou um pico de cálcio mais elevado do que os cimentos MTA Fillapex, GuttaFlow Bioseal, Adseal e Syntex. O MTA Fillapex continha uma quantidade mais elevada de tungstato. O Sealapex apresentou o maior valor de radiopacidade entre os materiais testados (p < 0,05), enquanto que a MTA Fillapex foi o material menos radiopaco (p < 0,05). Cada cimento endodôntico contém diferentes composições de radiopacificadores incluindo óxido de bismuto, tungstato de cálcio e óxido de zircônio. Os cimentos testados apresentaram valores de radiopacidade acima do limite especificado pela ISO. Sealapex foi o cimento obturador mais radiopaco seguido por GuttaFlow Bioseal, Syntex, Adseal e MTA Fillapex.

Debris Removal Using a Hydroxyapatite Nanoparticle-Containing Solution (Vector Polish) with Sonic or Ultrasonic Agitation.

Chemomechanical preparation of the root canal system is considered to be the most important part of root canal treatment, including both mechanical removal of tissue remnants and dentine chips, and chemical elimination of biofilm and microorganisms. A number of different solutions and agitation techniques have been proposed for that purpose. It was the aim of the present study to investigate whether root canal cleanliness can be improved by using a hydroxyapatite nanoparticle-containing solution with and without sonic or ultrasonic agitation. Seventy-four single-rooted teeth were divided into four experimental groups (n = 15) and two control groups (n = 7). All teeth were split longitudinally and a groove and three holes were cut into the root canal wall and filled with dentinal debris. Final irrigation was performed using sodium hypochlorite or a hydroxyapatite nanoparticle-containing solution (Vector polish) activated with a sonically or an ultrasonically driven endodontic file. Two calibrated investigators rated the remaining debris using a four-score scale. The results were analyzed using a non-parametric test with α < 0.05. Sonic and ultrasonic irrigation with sodium hypochlorite cleaned the grooves and holes well from debris. The hydroxyapatite nanoparticles activated by a sonic file cleaned grooves and holes equally well. Ultrasonically activated nanoparticles performance was clearly inferior. The syringe control-group left large amounts of debris in grooves and holes. The use of the hydroxyapatite nanoparticles used in this study did not improve removal of debris.

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

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.

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

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.

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

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.

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.

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.

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

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.