Influence of pulse energy, tip design and insertion depth during Er:YAG-activated irrigation on cleaning efficacy in simulated severely curved complex root canal systems in vitro.

AIM: To investigate the influence of pulse energy, tip geometry and tip position in simulated 3D-printed root canals with multiple side canals at different levels in all directions on the cleaning performance of laser-activated irrigation (LAI) compared to sonic activation (EDDY) and conventional needle irrigation (NI). METHODOLOGY: 3D-printed root canal models (25/.06, length 20 mm, curvature 60°, radius 5 mm) with side canals (diameter 0.2 mm) at 2, 5 and 8 mm from the apex were filled with coloured biofilm-mimicking hydrogel. LAI (Morita AdvErL Evo, Kyoto, Japan) was performed with six settings (n = 20; pulse-energy, pulses per second [PPS], tip position): LAI1 (50 mJ, 25 PPS, P400FL, canal entrance [CE]), LAI2 (same as LAI1, but insertion depth 9 mm before the apical endpoint [AE] [corresponding to 1 mm above the first lateral canals]), LAI3 (80 mJ, 25 PPS, P400FL, 9 mm before AE), LAI4 (same as LAI 3, but at CE) for 3 × 20 s each, LAI5 (50 mJ, 25 PPS, P400FL 2 × 20 s, CE & R200T (30 mJ, 25 PPS, 1 × 20 s, 9 mm before AE), LAI6 (30 mJ, 25 PPS, R200T, 9 mm before AE, 3 × 20 s). A continuous irrigation (3 mL/20 s) using distilled water accompanied the irrigation cycles. NI and EDDY (3 × 20 s each; 3 mL/20 s irrigation, insertion AE minus 1 mm, amplitude 4 mm) served as control groups. Biofilm-mimicking hydrogel removal (ImageJ, NIH) was assessed for the entire system, the central canal and the lateral canals using standardized photographs with a microscope (Expert DN, Müller-Optronic) and statistically analysed was performed using Kruskal-Wallis and Dunn tests (p = .05). Irrigant extrusion beyond the foramina was also recorded. RESULTS: LAI2 (99.08%; interquartile range [IQR]: 96.85-100.00) and LAI3 (97.50%; 96.24-100.00) achieved the significantly best and LAI6 (80.08%; 73.41-84.69) the significantly worst removal of hydrogel from the entire root canal system amongst all LAI configurations (p < .05). There were no significant differences between LAI6, EDDY (72.89%; 67.49-76.22) and manual irrigation (54.39%; 51.01-56.94) (p > .05). R200T laser tip caused significantly more often irrigant extrusion than all other techniques (p < .05). CONCLUSION: Tip design, energy settings, and the positioning of the laser tip below the canal entrance caused an improvement in cleaning performance of the LAI. However, the small R200T tip created significantly more procedural errors (irrigant extrusion) due to higher concentrated energy.

Effectiveness of root canal instrumentation for the treatment of apical periodontitis: A systematic review and meta-analysis.

BACKGROUND: The development of endodontic instruments has rapidly advanced, but their impact on endodontic outcome parameters remains unclear. OBJECTIVES: This systematic review aimed to answer the following PICOT questions: In patients with apical periodontitis (P) what is the effectiveness of root canal instrumentation ([Q1] performed with contemporary techniques [I] in comparison with 'traditional' techniques [C]] and ([Q2] performed with contemporary engine-driven NiTi instruments [I] compared with other types of contemporary engine-driven NiTi instruments [with different design and/or technology] [C]) in terms of clinical and patient-related outcomes (O)? METHODS: After PROSPERO protocol registration, a literature search was conducted using Clarivate Analytics' Web of Science, Scopus, PubMed and Cochrane Central Register of Controlled Trials. Grey literature and major journal contents were examined. Two independent reviewers performed the study selection, data extraction and appraisal of included studies. A quantitative meta-analysis was considered, and statistical heterogeneity and overall quality of evidence were assessed. RESULTS: Nine studies were identified showing substantial methodological differences. Five studies addressed PICOT 1 and three PICOT 2, whereas one study aimed both. A random-effects meta-analysis model was considered for the outcome 'radiographic evidence of normal periodontal ligament space or reduction of apical lesion size' (PICOT 1) based on three studies with 332 evaluable participants and showed that contemporary instrumentation was associated with a more favourable outcome (p = .005) compared with root canal preparation with stainless steel instruments (odds ratio = 2.07 [95%-confidence interval = 1.25-3.44]) with no evidence of statistical heterogeneity (I2  = 0%) but low quality of evidence. DISCUSSION: Albeit a few studies fulfilled eligible criteria, no study had a low risk of bias. Compelling evidence indicating significantly different outcome rates using different endodontic instruments when treating teeth with apical periodontitis is lacking. CONCLUSIONS: In terms of healing, the results of the meta-analysis determined the higher effectiveness of root canal instrumentation performed with contemporary techniques in comparison with conventional stainless steel instruments in patients with apical periodontitis followed for a minimum of 1 year with low quality of evidence. No differences could be demonstrated between preparations with traditional stainless steel and contemporary NiTi instruments for other clinical and patient-related outcomes. REGISTRATION: PROSPERO (CRD42021274642).

Guided endodontics versus conventional access cavity preparation: an ex vivo comparative study of substance loss.

BACKGROUND: To compare the outcomes of conventional access cavity preparation (CONV) versus guided endodontics (GE) for access cavity preparation in anterior teeth with pulp canal calcification (PCC) regarding root canal detection, substance loss, procedural time, and need for additional radiographs. METHODS: Extracted, sound human teeth with PCC (n = 108) were matched in pairs, divided into two groups and used to produce 18 models. An independent endodontist and a general dentist performed access cavity preparation under simulated clinical conditions on nine models each (54 teeth). The endodontist used the conventional technique and the general dentist GE. Time needed to access the root canals and the number of additional radiographs were recorded. Pre- and postoperative cone-beam computed tomography scans were obtained to measure substance loss. Statistical significance was tested by examining the overlap of 95% confidence intervals (CIs) between the groups. RESULTS: All root canals were successfully accessed by both methods. There were no significant differences in substance loss (CI: CONV 15.9-29.6 mm3 vs. GE 17.6-27.5mm3) or procedural time (CI: CONV 163.3-248.5 s vs. GE 231.9-326.8 s). However, 31 additional radiographs were required for GE compared to none for CONV. CONCLUSIONS: For access cavity preparation in teeth with PCC, both CONV by a specialist and GE by a general dentist produce good results in terms of substance loss and time requirements.

A critical analysis of research methods and experimental models to study the physical properties of NiTi instruments and their fracture characteristics.

The aim of this review is to provide a critical overview of the physical properties (surface hardness, cutting efficiency, bending properties, flexibility and cyclic fatigue resistance) of NiTi instruments. Frequently used experimental models regarding these aspects will be presented and discussed with regard to their strengths and weaknesses. For all these aspects, a plethora of experimental models have been described. Based on a critical appraisal and especially taking the appropriate translation of experimental findings to clinical endodontics into account, suggestions for future research based on clearly defined and valid experimental methodologies will be provided. Up to now, very few attempts have been made to assess which particular physical properties of NiTi instruments exert an impact on the clinical outcome of root canal treatment. Departure from merely focusing on physical properties and fracture characteristics towards more biological aspects in terms of treatment outcome is essential.

Quality of root canal fillings and prevalence of apical radiolucencies in a German population: a CBCT analysis.

OBJECTIVES: The aim of this study was to determine the frequency and quality of root canal fillings (RCF) and the prevalence of apical radiolucency (AR) in a German population. MATERIAL AND METHODS: Five hundred randomly selected full-size CBCT images (Planmeca ProMax 3D, FOV = 8 × 8 cm, voxel size 160 µm or 200 µm) were obtained from German patients (40.6% = ♂; 59.4% = ♀; mean age = 50.21 ± 12.45 years). A total of 8254 teeth were examined for pathology (AR, widened periodontal ligament). The relationship between AR and existing RCF and the quality of RCF were documented. Frequency and correlations between the left and right sides and gender distribution were analyzed statistically using the chi-square test. RESULTS: The overall prevalence of AR was 3.8%, whereas for teeth with RCF, it was 42.5%. Patients had approximately 1.4 root canal-filled teeth (8.2% of all teeth). RCF terminated more than 2 mm short of the radiological apex in 31.2%, 5.1% reached beyond the apex, 8.1% were associated with extruded sealer, and 5.3% presented untreated root canals. Odds ratio of having an AR was highest in teeth with RCF beyond the apex (OR = 27.0) followed by RCF <2 mm short of the apex (OR = 4.4), untreated root canals (OR = 2.9), and inhomogeneity of RCF (OR = 1.2). Extrusion of sealer was least associated with AR. Molars were most frequently associated with AR (P < 0.05). Root canal-filled teeth showed significantly more AR in men compared with women (P < 0.05). CONCLUSIONS: About 42.5% of root canal-filled teeth were associated with AR, and in about one-third of these teeth, the RCF terminated more than 2 mm short of the apex. CLINICAL RELEVANCE: Each step in root canal therapy influences treatment outcome and prevalence of periapical radiolucencies. Determination of the working length is still one of the key points to achieve predictable periapical healing, and homogenous root canal filling reaching the foramen major seems to be essential.

Impact of new cross-sectional designs on the shaping ability of rotary NiTi instruments in S-shaped canals.

The aim was to compare the shaping ability of different rotary nickel-titanium instruments in simulated S-shaped canals. One hundred S-shaped canals in resin blocks were prepared to an apical size 25 using F6 SkyTaper (Komet), Silk Files .04, Silk Files .06, Prototypes .04, and Prototypes .06 (all Mani) (20 canals/group). Material removal was measured at 20 measuring points, beginning 1 mm from the endpoint of preparation. Incidence of canal aberrations, preparation time, and instrument failures were also recorded. Statistical analyses were performed using ANOVA, Student-Newman-Keuls and Chi-square test. Pooled data of all measuring points revealed that canals instrumented with Prototypes .04 were significantly better centered than those prepared with all other instruments, while Prototypes .06 and both Silk Files performed significantly better than F6 SkyTaper (p < 0.05). The preparation time differed significantly between all groups and Prototypes .04 allowed the fastest preparation (p < 0.05). There was no statistically significant association between type of instrument and incidence of aberrations (p > 0.05). The cross-sectional design had a marked impact on the shaping ability of the instruments, and less tapered instruments maintained the original canal curvature better than instruments having greater tapers.

Shaping ability of reciprocating single-file systems in severely curved canals: WaveOne and Reciproc versus WaveOne Gold and Reciproc blue.

The aim was to compare the canal straightening of M-wire [Reciproc (VDW, Munich, Germany) and WaveOne (Dentsply Maillefer, Ballaigues, Switzerland)] and gold- and blue-wire heat-treated [Reciproc blue (VDW) and WaveOne Gold (Dentsply Maillefer)] instruments in severely curved root canals. A total of 80 root canals in extracted human teeth with angles of curvatures ranging between 25° and 35° and radii ranging between 3.1 and 8.5 mm were divided into four groups (n = 20). Based on radiographs taken prior to instrumentation, the groups were balanced with respect to the angle and the radius of canal curvature (P = 1.0 and P = 1.0, respectively). All canals were prepared to an apical size 25 according to the manufacturers' instructions. Pre- and post-instrumentation radiographs were superimposed and canal straightening was analysed using a computer imaging programme. Preparation time and instrument failure were also recorded. Data were analysed statistically using ANOVA and Student-Newman-Keuls test. During preparation no instrument fractured. All instruments maintained the original canal curvature well with no significant differences between the instruments (P = 0.278). Regarding preparation time, no significant differences between the four instruments were obtained (P > 0.05). Under the conditions of this study, all instruments respected the original canal curvature well. Instruments were safe to use. The use of the gold- and blue-wire heat-treated instruments was not associated with an improved shaping ability.

Endodontic sealers based on calcium silicates: a systematic review.

Recently, sealers based on calcium silicates were developed as a new class of endodontic sealers. Inspired by the excellent sealing ability and biocompatibility of calcium silicate-based cements, these sealers establish a biological point of view on the obturation of root canals. No longer, the bacteria-tight seal against reinfection of the root canal is the only goal of root canal obturation. Antibacterial properties as well as bioactive inducement of periapical healing and hard tissue formation are added to the portfolio of sealers. Ready-to-use sealers consisting of only one component with a need for external water supply from, e.g., body fluid and two components sealers with internal water supply were introduced to the market. Both of these material types have the same setting reactions in common whereby a hydration reaction of the calcium silicate is followed by a precipitation reaction of calcium phosphate. Though the available sealers are all based on calcium silicates, they consist of different compositions. Due to this aspect, differences in their physical and chemical properties as well as in their in vitro characteristics were described. Studies addressing the clinical impact of calcium silicate-based sealers on outcome are still sparse. The bioactive potential of sealers based on calcium silicates is a consequence of the slight solubility of these materials even after setting, but solubility of the sealer might also compromise the quality of sealing a root canal against regrowth and reinfection. Further clinical investigations are required to evaluate the clinical relevance of the gulf between bioactivity and solubility.

Review of the dental implications of X-linked hypophosphataemic rickets (XLHR).

OBJECTIVES: The aim of this article was to review the dental implications of X-linked hypophosphataemic rickets (XLHR) and to provide suggestions regarding the dental treatment of these patients. MATERIALS AND METHODS: The following search items "x-linked hypophosphataemia, hypophosphataemic rickets, vitamin D-resistant rickets" were used for literature search. Only full-text articles were analysed and summarized to get an overview of the different treatments and outcomes of hypophosphataemic patients. RESULTS: Radiographically, very large pulp chambers with an abnormally high pulp volume/tooth volume ratio, suggesting taurodontism, are often evident. The affected teeth are characterised by a thin enamel layer and dentinal defects. The gender distribution of hypophosphataemic patients is almost equal, but postpubertary males seem to show a trend to develop more severe dental symptoms of the disease. Abscesses without any signs of dental caries or trauma are frequent findings. The most often affected teeth are incisors followed by molars and premolars. CONCLUSIONS: Treatment options include frequent dental examination, application of topical fluoride varnish and sealing of pits and fissures to prevent microbial invasion that may result in pulpitis and further endodontic complications. CLINICAL RELEVANCE: X-linked hypophosphataemic rickets is associated with marked structural alterations of dental hard tissues and the development of multiple abscesses and sinus tracts of dental origin. Therefore, profound knowledge of the various dental implications of XLHR is required to provide these patients with the best possible treatment options.

Selected physicochemical properties of AH Plus, EndoREZ and RealSeal SE root canal sealers.

The aim of this laboratory study was to assess selected physicochemical properties of three root canal sealers. The solubility, setting time and radiopacity of AH Plus, EndoREZ and RealSeal SE were evaluated. The solubility was determined by weight loss of specimens in water over a period of 28 days. Setting time and radiopacity were assessed according to ANSI/ADA and ISO specifications using an aluminum step wedge calibrated in millimeters and the intendention test using a Gilmore needle. Data were analyzed using ANOVA and the Student-Newman-Keuls test for pairwise comparisons. AH Plus was significantly less soluble, showed the significantly highest radiopacity and displayed the significantly longest setting time of all sealers (P < 0.01). At all exposure times, EndoREZ was significantly more soluble than the other sealers (P < 0.01) and displayed the significantly lowest values regarding radiopacity (P < 0.01). Analysis showed that setting time and radiopacity for all sealers met the ANSI/ADA and ISO standards. Solubility of AH Plus and RealSeal confirmed the ANSI/ADA and ISO specification, while EndoREZ clearly exceeded the proposed solubility value. Out of all sealers tested, AH Plus obtained the best values for all properties.

Cyclic Fatigue of Different Reciprocating Endodontic Instruments Using Matching Artificial Root Canals at Body Temperature In Vitro.

Reciprocating motion expands the lifetime of endodontic instruments during the preparation of severely curved root canals. This study aimed to investigate the time to fracture (TTF) and number of cycles to failure (NCF) of different reciprocating instruments (n = 20 in each group) at body temperature using a dynamic testing model (amplitude = 3 mm). Reciproc Blue (RPB), size 25/.08, WaveOne Gold (WOG) 25/.07, Procodile (Proc) 25/.06, R-Motion (RM_06) 25/.06 and R-Motion (RM_04) 30/.04 instruments were tested in their specific reciprocating motion in artificial matching root canals (size of the instrument ± 0.02 mm; angle of curvature 60°, radius 5.0 mm, and centre of curvature 5.0 mm from apical endpoint). The number of fractured instruments, TTF, NCF, the and lengths of the fractured instruments were recorded and statistically analysed using the Chi-Square or Kruskal-Wallis test. Both TTF (median 720, 643, 562, 406, 254 s) and the NCF (3600, 3215, 2810, 2032, 1482 cycles) decreased in the following order RM_06 > RPB > RM_04 > Proc > WOG with partially significant differences. During testing, only six RM_06 instruments fractured, whereas 16/20 (RPB), 18/20 (Proc), and 20/20 (RM_04, WOG) fractures were recorded (p < 0.05). Within the limitations of the present study, blue-coloured RPB and RM instruments exhibited a significantly superior cyclic fatigue resistance compared to SE-NiTi and Gold-wire instruments. Heat treatment, cross-sectional design and core mass significantly influenced the longevity of reciprocating instruments in cyclic dynamic testing.

Comparative Analysis of Irrigation Techniques for Cleaning Efficiency in Isthmus Structures.

INTRODUCTION: This study aimed to evaluate the removal of a biofilm-mimicking hydrogel from isthmus structures in a simulated complex root canal system consisting of 2 curved root canals by Laser-activated irrigation (LAI, AdvErl Evo, Morita) and mechanical activation techniques. METHODS: A 3D-printed root canal model with 2 parallel root canals (60°-curvature, radius 5 mm, dimension 25/.06) with a total length of 20 mm connected via isthmuses (2.5 × 0.4 × 0.2 mm) at 5 mm and 8 mm from the apical endpoint and with lateral canals (diameter 0.2 mm) in all directions at 2, 5, and 8 mm from the apex was filled with a colored biofilm-mimicking hydrogel. Irrigation protocols under continuous irrigation with distilled water (3 × 20s per root canal; 3 ml/20s; n = 20) included conventional needle irrigation (=NI); manual agitation (=MA, gutta-percha point 25/.06); EndoActivator (=SAI-EA, 25/.04); EDDY (=SAI-E, 25/.04); ultrasonically-activated irrigation (=UAI) and LAI (Er:YAG-laser; P400FL tip at canal entrance; 25pps, 50 mJ, 300µs). Removal of the hydrogel was determined as a percentage via standardized photos through a microscope. Statistical analysis was performed using Kruskal-Wallis and Conover tests (P = .05). RESULTS: Laser-activated irrigation (LAI) was associated with the greatest removal of hydrogel from the entire root canal system (P < .05), followed by SAI-E. No significant differences were reported for the coronal isthmus between LAI, SAI-E, NI, and MA (P > .05), but inferior results for SAI-EA and UAI (P < .05). In the apical isthmus, all techniques outperformed UAI (P < .05), with LAI, SAI-E, and NI showing the best results (P < .05). CONCLUSIONS: Laser-activated irrigation (LAI) was superior to other irrigation techniques in the entire root canal system. SAI-E and NI performed comparable to LAI in the isthmuses.

Cleaning Efficiency of Different Irrigation Techniques in Simulated Severely Curved Complex Root Canal Systems.

INTRODUCTION: To compare the biofilm-mimicking hydrogel removal efficiency of laser-activated irrigation (LAI) with five other irrigation techniques in simulated curved root canals with lateral canals. METHODS: Three-dimensional-printed root canal models (60°-curvature, radius 5 mm; dimension 25/.06) with a total length of 20 mm and lateral canals in all directions at 2, 5, and 8 mm (diameter 0.2 mm) from the apex were filled with a colored biofilm-mimicking hydrogel. The following protocols (each 3 × 20 seconds continuous irrigation with distilled water 3 ml/20 seconds; n = 20) were carried out: conventional needle irrigation; manual agitation ([MA], gutta-percha point 25/.06); EndoActivator (=sonically-activated irrigation EndoActivator, 25/.04); EDDY (=sonically-activated irrigation EDDY [SAI-E]; 25/.04); ultrasonically-activated irrigation and LAI (Erbium-doped Yttrium Aluminum Garnet laser; P400FL tip at canal entrance; 25 pps, 50 mJ, 300 µs). Standardized photos were taken with a microscope and the removal of the hydrogel was determined as a percentage for the entire system, the main canal and the lateral canals. Statistical analysis was performed using analysis of variance and Scheffé test (P = .05). RESULTS: LAI (89.3% ± 5.9%) showed the greatest hydrogel removal followed by SAI-E (65.5% ± 3.3%) and ultrasonically-activated irrigation (59.1% ± 4.7%), with significant differences between these groups (P < .05). Needle irrigation, MA, and sonically-activated irrigation EndoActivator performed equally (P > .05) and obtained the significantly lowest values (P < .05). LAI and SAI-E showed the significantly best hydrogel removal from the main canal (P < .05). At all three levels, LAI removed significantly more hydrogel from the lateral canals than all other techniques (P < .05). CONCLUSIONS: LAI was superior to other techniques in both the entire system and the lateral canals in removing the hydrogel. SAI-E achieved comparable results in the main canal.

Parallel endodontic education via social media: An exploratory survey study.

There is insufficient research to evaluate social media's influence on endodontic education. Therefore, this study assessed the percentage of students utilising Facebook in their education and the factors influencing their engagement. A survey was conducted on dental students, interns and dentists undertaking specialist programmes. Categorical data were analysed using Fisher's Exact test and multiple pairwise comparisons. The significance level was set at p < 0.05. Responses were received from 801 participants, with 98.4% using Facebook for endodontic knowledge. Although most students knew that scientific evidence is not always provided, they still deemed such information valuable as it was a practical demonstration of clinical cases. Most students turn to Facebook for endodontic education to compensate for the gap between their academic education and clinical practice. The utilisation of social media for education can be a concerning phenomenon and should not be ignored by academic institutes.

Assessment of the Prevalence of Radix Entomolaris and Distolingual Canal in Mandibular First Molars in 15 Countries: A Multinational Cross-sectional Study with Meta-analysis.

AIM: The aim of this study was two-folded: i) to assess the prevalence of Distolingual Canal (DLC) and Radix Entomolaris (RE) in Mandibular First Molars (M1Ms), using Cone Beam Computed Tomography (CBCT) images and ii) to assess the impact of sociodemographic factors on the prevalence of these conditions worldwide. METHODS: CBCT images were scanned retrospectively and the ones including bilateral M1Ms were included in the study. The evaluation was performed by 1 researcher in each country, trained with CBCT technology. A written and video instruction program explaining the protocol to be followed step-by-step was provided to all observers to calibrate them. The CBCT imaging screening procedure consisted of evaluating axial sections from coronal to apical. The presence of DLC and RE in M1Ms (yes/no) was identified and recorded. RESULTS: Six thousand three hundred four CBCTs, representing 12,608 M1Ms, were evaluated. A significant difference was found between countries regarding the prevalence of both RE and DLC (P < .05). The prevalence of DLC ranged from 3% to 50%, and the overall prevalence was 22% (95% CI: 15%-29%). RE prevalence ranged from 0% to 12%, and the overall prevalence was 3% (95% CI: 2%-5%). There were no significant differences between left and right M1Ms or between genders for either DLC or RE (P > .05). CONCLUSION: The overall prevalence of RE and DLC in M1Ms was 3% and 22%. Additionally, both RE and DLC showed substantial bilaterally. These variations should be considered by endodontic clinicians during endodontic procedures in order to avoid potential complications.

A comparative evaluation of gutta-percha filled areas in curved root canals obturated with different techniques.

The aim of this study was to compare different obturation techniques in severely curved canals in terms of the percentage of gutta-percha filled area and voids. The obturation times and the incidence of extrusion of filling material were also compared. Curved root canals (curvature, 25-35°) of 48 extracted human teeth were enlarged with Mtwo rotary NiTi instruments and obturated as follows: Group A: 0.04/35 matched-single-cone; Group B: cold lateral compaction with 0.04/35 gutta-percha master cone; Group C: warm vertical compaction; Group D: lateral compaction with standardized gutta-percha master cone. In all groups AHPlus was used as sealer. The teeth were sectioned horizontally at 2, 3, 4, 6 and 8 mm from the apex. The total area of each canal segment was measured and the areas of gutta-percha, sealer and voids were converted to percentages of the total area. Data were subjected to the Kruskal-Wallis and post hoc Dunn test. Obturation times were compared using ANOVA and post hoc Student-Newman-Keuls test. The matched-single-cone obturation (group A) was significantly the fastest method while warm vertical compaction (group C) required significantly more time than all other techniques (p < 0.05). No significant differences were obtained between the groups in terms of percentage of voids at any level (p > 0.05). At all levels, groups B, C, and D produced significantly higher gutta-percha filled areas (p < 0.05) and lower sealer-filled areas (p < 0.05) than group A. No significant differences were found between groups B, C, and D (p > 0.05) regarding gutta-percha and sealer-filled areas. Within the limitations of the in vitro study, it can be concluded that lateral compaction of greater taper gutta-percha cones is a fast and efficient method for obturation of curved canals.

Impact of nickel-titanium instrumentation of the root canal on clinical outcomes: a focused review.

Nickel-titanium (NiTi) root canal instruments have improved the technical quality of enlarging and shaping. These instruments have been shown to prepare even severely curved root canal with fewer procedural errors than traditional stainless steel hand instruments. While it would appear that these instruments might enhance clinical outcomes, very few studies have assessed their impact when used in primary root canal treatment. Clinical studies investigating the outcome of primary root canal treatment using nickel-titanium hand or rotary instruments were identified (MEDLINE database) using appropriate key words in an attempt to determine if there have been enhanced outcomes with these instruments. Evidence from one clinical trial suggests that (i) better maintenance of the original canal curvature and shape results in increased success rates and (ii) that ledging of root canals results in reduced success rates. Evidence from two studies indicates that the use of NiTi-either hand or rotary-instruments significantly increases success rates of primary nonsurgical root canal treatment compared with the use of stainless steel hand instruments, while three investigations failed to show any significant differences.

Short and Long-Term Solubility, Alkalizing Effect, and Thermal Persistence of Premixed Calcium Silicate-Based Sealers: AH Plus Bioceramic Sealer vs. Total Fill BC Sealer.

This study aimed to investigate the short- and long-term solubility, alkalizing potential, and suitability for warm-vertical compaction of AH Plus Bioceramic Sealer (AHBC), and Total Fill BC Sealer (TFBC) compared to the epoxy-resin sealer AH Plus (AHP). A solubility test was performed according to ISO specification 6876 and further similar to ISO requirements over a period of 1 month in distilled water (AD) and 4 months in phosphate-buffered saline (PBS). The pH of the immersion solution was determined weekly. Sealers were exposed to thermal treatment at 37, 57, 67, and 97 °C for 30 s. Furthermore, heat treatment at 97 °C was performed for 180 s to simulate inappropriate implementation of warm vertical filling techniques. Physical properties (setting time, flow, film thickness according to ISO 6876) and chemical properties (Fourier transformed infrared spectroscopy) were assessed. AHBC and TFBC were associated with significantly higher solubility than AHP over 1 month in AD and 4 months in PBS (p < 0.05). AHBC and TFBC both reached high initial alkaline pH, while TFBC was associated with a longer-lasting alkaline potential than AHBC. Initial pH of AHBC and TFBC was higher in AD than in PBS. None of the sealers were compromised by thermal treatment.

Real-time intracanal temperature measurement comparing mechanically and laser-activated irrigation to syringe irrigation.

Antibacterial activity and tissue dilution of sodium hypochlorite (NaOCl) are improved by moderately heating the irrigant. Temperature can be risen by preheating or intracanal activation. To assess intracanal temperature development of NaOCl during irrigation activation and syringe activation (SI) in a closed system at 37°C, Type-K thermocouples were inserted close to the root canal of one human single-rooted maxillary canine at the apex and 5 and 10 mm from the apical foramen via drilled holes. The root was positioned in a plastic vial filled with alginate simulating surrounding biological structures. Experiments were performed in a closed environment at 37°C (n = 14): EA: EndoActivator (Dentsply Sirona), EDDY: EDDY (VDW), PUI: passive ultrasonic irrigation, PIPS: Photon-induced photoacoustic streaming (Fotona), S60: SI of 60°C-NaOCl, S45: SI of 45°C-NaOCl, and S20: SI of 20°C-NaOCl. S45, PUI and EDDY lead to minor intracanal temperature increases. EA and PIPS did not influence the intracanal temperature. SI with 60°C-NaOCl resulted in higher intracanal temperatures than activation systems. Temperature dissipation into simulated tissues buffered intracanal temperature changes.

Effect of Core Mass and Alloy on Cyclic Fatigue Resistance of Different Nickel-Titanium Endodontic Instruments in Matching Artificial Canals.

Instrument failure during root canal preparation is still a concern among endodontists. However, it remains unclear whether the use of more martensitic alloys or the cross-sectional design parameters (i.e., core mass) significantly improve fracture resistance. The aim of the study was to evaluate the impact of core mass and alloy on dynamic cyclic fatigue resistance of nickel-titanium endodontic instruments in matching artificial canals at body temperature. Two groups were tested. (A) taper 0.04: F360 (Komet, Lemgo, Germany), Twisted file (Sybron Endo, Glendora, CA, USA) (=TF), JIZAI (Mani, Tochigi, Japan) (=J_04) (all size #25) and the variable tapered TruNatomy (Dentsply, Ballaigues, Switzerland) (size #26) (=TN). (B) size #25; taper 0.06: (Mtwo (VDW, Munich, Germany), JIZAI (Mani) (=J_06), and variable tapered Hyflex EDM OneFile (Coltene Whaledent, Altstätten, Switzerland) (=HF). Time, number of cycles to fracture (NCF), and number and length of fractured fragments were recorded and statistically analysed using ANOVA Student-Newman-Keuls, Kruskal-Wallis or Chi-square test (significance level = 0.05). (A) TN showed the significantly shortest time until fracture, followed by TF, F360 and J_04 which also differed significantly, while NCF showed the following order: F360 < TN < TF < J_04 (p < 0.05). Only one J_04 but all instruments of the other groups fractured within the test-limit of 10 min. (B) Mtwo was significantly inferior concerning time until fracture and NCF, compared to J_06 and HF (p < 0.05), which did not differ significantly (p > 0.05). While all Mtwo instruments fractured, only four instruments failed in the other groups (p < 0.05). Within the limitations of this study, alloy and cross-sectional design (i.e., core mass) were critical factors regarding instrument failure, but none of these factors could be determined as a main parameter for increased or decreased time, and cycles to fracture. Rather, it seemed to be the interaction of multiple factors (e.g., longitudinal and cross-sectional design, alloy, and rotational speed) that was responsible for differences in the time and cycles to fracture. Nonetheless, all instruments had lifetimes that allow safe clinical use. However, the superiority or inferiority of an instrument with regard to cyclic fatigue based on laboratory results-even when identical trajectories are guaranteed-may be considered questionable, as the characteristics and design parameters of the instruments vary considerably, and the experimental setups lack additional clinical parameters and thus clinical relevance.