Apical Third Of Root Research Articles

Testing a new micro-osteoperforation modality on the rate of orthodontic tooth movement in a rabbit model

Objectives. The current study objective was to test and compare the impact of a new micro-osteoperforation (MOP) modality with 2 other modalities on the rate of tooth movement (RTM) in rabbits. Methods. The sample comprises 45 adult male albino rabbits aged 24 weeks and divided equally into 3 groups regarding MOP modalities; a single vertical MOP (1V-MOP), a single vertical MOP + 2 horizontal MOPs (1V+2H-MOP), as the new MOP design; and 3 horizontal MOPs (3H-MOP). The first right mandibular premolar (RMP1) received MOP(s) + orthodontic force 50g by traction spring. The contralateral tooth on left (LMP1), as positive (+ve) control, received only 50g orthodontic force by another spring. Both springs were fixed by a mini-screw between the 2 lower incisors. Evaluations of the clinical RTM and histopathology with H and E stain of the compressed PDL at the cervical, middle, and apical thirds of MP1 root were performed for comparing after 1, 2, and 3 weeks of OTM respectively. Results. The RTM (P<0.001) and number of osteoclasts, osteoblasts, blood vessels and PDL width (P<0.001 to P=0.039) significantly increased in the MOP groups; the 1V+2H-MOP was in between the higher 1V-MO P and the lower 3H-MOP. Conclusion. All MOP modalities could efficiently accelerate RTM and increase the activity of the compressed PDL, but with a variant rate. The new 1V+2H-MOP modality can be chosen as the best modality for faster RTM, because it showed moderate RTM after the 1V-MOP.

Effectiveness of chitosan nanoparticles, and novel chemical irrigants with surfactant on smear layer removal and microhardness alteration

ObjectiveThis current study was designed to compare and correlate between smear layer eradication and reduction in microhardness by natural 0.2%chitosan nanoparticles and novel chemical irrigants with surfactant at the apical root third. Materials and methodOne hundred and twenty straight single-rooted extracted lower premolars were decoronated and working length obtained with #10 K-file. Pro-taper rotary files were used till apical size F3. The canals were simultaneously flushed with assigned irrigant containing surfactant [(ChX-Ultra, NaOCl-Extra, Pro-EDTA, 0.2%chitosan nanoparticles, Biopure MTAD]. The samples were randomly divided into two equal groups (n = 60). InGroup S (n = 60), the residual smear layer was examined by scanning electron microscope and in Group M(n = 60) microhardness was determined by Vickers Microhardness Tester. Further both groups were divided into six equal groups (n = 10 each) according to assigned irrigating solutions.For smear layer removal; Kruskal-Wallis tests followed by pair wise comparison using Mann Whitney U test was done. For change in microhardness ANOVA and post hoc Tukey tests was done. ResultsMaximum smear layer removal was recorded in Biopure MTAD (1.8 ± 0.63), followed by pro-EDTA (2.2 0 ± 0.63) then 0.2%chitosan (2.6 ± 0.51), then NaOCL Extra (3.5 ± 0.53)and least in CHX-Ultra (4.4 ± 0.52) and saline (5.0 ± 0.00). Pro-EDTA group (12.8 ± 2.47) revealed significant highest reduction in microhardness followed by Biopure MTAD (8.01 ± 3.06), 0.2%chitosan nanoparticles (5.48 ± 2.87), NaOCl-Extra (5.44 ± 1.62) and least recorded in CHX-Ultra (4.94 ± 1.43) and saline (3.04 ± 0.63). ConclusionThe elimination of the smear layer is always accompanied by a reduction in microhardness. Moreover, irrigant with surfactant and chelators enhanced smear layer removal, with best perceived in Biopure MTAD.

An in-vitro study on effects of laser activation on dye penetration in human root dentin.

To evaluate the penetration of a dye in root dentin after activation with different laser wavelengths. Palatal roots of 38 human molars were enlarged and disinfected. Irrigation activation was performed with an Er:YAG laser: @50 mJ, 15 Hz (Er:YAG); a 9.3 µm CO2 laser: @40% power (CO2); diode lasers 455 nm/970 nm: @0.8 W, 15 Hz (D455, D970) and 808/980 nm: @1 W (D808, D980) and compared to positive control: etching with 35% H3PO4 (POS); negative control: water (NEG) and conventional needle irrigation: NaOCl and ethylenediaminetetraacetic acid (EDTA) (CONV). Methylene blue solution was introduced in the canal and laser-activated or left untouched for 100 s before the roots were dried and cut into horizontal slices. Dye penetration was automatically calculated by color recognition of two samples per root third (n = 8 per group in each coronal, middle and apical root thirds). The presence and absence of a smear layer was checked in two additional samples of the negative and positive control under scanning electron microscopy (SEM). Full-depth infiltration was not achieved in any group. Dye penetration in CONV was significantly less than in Er:YAG, CO2, POS, D455, D970, D808 and similar to NEG and D980 when results of different root thirds were pooled. Laser activation using certain parameters enhanced dye penetration compared to conventional needle irrigation with NaOCl and EDTA (CONV).

Micro-CT Assessment of Filling Removal Effectiveness in the Apical Third of Curved Canals with Different Types of Anatomy.

The aim of this study was to assess the effectiveness of filling removal material from the apical third of curved mesial root canals of mandibular molars. Reciprocating instrumentation followed by additional rotary instrumentation with instruments made of alloys with different heat treatments was evaluated. Thirty-six mesial roots of mandibular molars were divided into two groups: Group Class IV consisted of 16 roots with two independent canals, and Group Class II consisted of 20 roots with two canals that merged into one at their apical level. Each of these two groups were further divided into two subgroups, according to the additional rotary instrument used after the reciprocating instrumentation: Group RH and Group RM for Hyflex and Mtwo, respectively. After each procedural step, the roots were scanned by micro-tomography. After each step of filling removal, the Wilcoxon matched pair test and the Mann-Whitney test were used for the evaluation between groups. The significance level adopted was 5%. Significant differences were observed between groups with different Class II and Class IV anatomies, regarding filling removal after Reciproc (P<0.05). After the use of an additional rotary instrumentation, no differences were observed between the two groups (P>0.05). In the apical third of mesial roots of mandibular molars with Class II anatomy, an additional rotary instrumentation was shown to be necessary for improving the removal of filling material after using the single-file reciprocating instrumentation technique.

Different Dentin Conditioning Protocols on Bond Strength of a Bioceramic Root Canal Filling.

Bioceramic-based sealers, in combination with bioceramic-coated gutta-perchas, have become more commonly used in root canal obturation. The present study aimed to assess the influence of laser-assisted dentin conditioning compared with conventional conditioning protocols on the push-out bond strength (PBS) of a bioceramic-based root canal filling. Sixty extracted mandibular premolars with one root canal were instrumented with EndoSequence rotary files up to size 40/0.04. Four types of dentin conditioning protocols were used: 1) 5.25% NaOCl (control), 2) 17% EDTA+5.25% NaOCl, 3) Diode laser-agitated 17% EDTA+5.25% NaOCl, 4) Er,Cr:YSGG laser irradiation+5.25% NaOCl. Teeth were obturated using the single-cone technique with EndoSequence BC sealer+BC points (EBCF). After having obtained 1-mm-thick horizontal slices from the apical, middle and coronal root thirds, push-out test was carried out, and failure modes were determined. The data were analyzed by two-way analysis of variance and Tukey's test with a significance level of p<0.05. The apical segments showed the highest PBS in all groups (p<0.05). In the apical segments, EDTA+NaOCl and diode laser agitated EDTA increased the PBS compared to the control (p=0.0001) and Er, Cr: YSGG laser (p=0.011 and p=0.027, respectively) groups. Both laser-used groups revealed significantly higher PBS values in the middle and coronal segments than EDTA+NaOCl (p<0.05). The bond failure was predominantly cohesive without any significant difference among the groups (p>0.05). Laser-assisted dentin conditioning had distinct effects on the PBS of the EBCF at different root segments. Although Er, Cr: YSGG was ineffective in the apical segments, generally, laser-assisted dentin conditioning affected PBS more favorably than conventional irrigation groups, with a more pronounced effect in the diode laser-agitated EDTA group.

The Roughening Effects of Er:YAG, Nd:YAG and KTP Laser Systems on Root Dentin Surface

Objectives: Present study aimed to evaluate the roughening ability of different laser systems on the middle and apical third of roots. Materials and Methods: Sixty extracted human single-rooted single canal mandibular premolar teeth were randomly assigned to 3 groups (n=20). Standardized preparation and sterilization procedures were performed. The samples were irradiated with Er:YAG, Nd:YAG, and KTP laser systems. The laser irradiations (1.5 Watt) were applied with a spiral motion, starting 1 mm short of the apex and then moving coronally for 10 sec, interleaved with 15-sec recovery intervals for each irradiation. This process was repeated twelve times. The roots that were standardized in the same length and thicknesses were divided parallel to the longitudinal axis. Then, the middle and apical 1/3 surface roughness values of each root section were measured using a profilometer and SEM analysis was performed. The data obtained were analyzed using the two-way analysis of variance (ANOVA) and Tukey post-hoc tests. Results: According to measurements obtained from middle and apical 1/3 surfaces; Although, the statistically highest roughness value was determined after Nd:YAG laser (P &amp;lt; 0.05), the statistically lowest value was detected following the Er:YAG laser irradiation (P &amp;lt; 0.05). Conclusions: In light of the present study, all laser systems caused significant roughness surface. Therefore, laser systems should be carefully applied in human root canals.

Evaluation of root resorption in the lower incisors after orthodontic treatment of skeletal Class III malocclusion by three-dimensional volumetric measurement with cone-beam computed tomography.

To investigate the volumetric changes of the lower incisor roots in skeletal Class III orthodontic patients with anterior crossbite after premolar extraction therapy. Thirty-six adults, aged 18-28 years, had four-premolar extraction treatment. Pre- and posttreatment cone-beam computed tomography (CBCT) images were used to assess the thickness and height of alveolar bone, root volume, and length. A paired t-test was used to detect changes in root volume and length before and after treatment. Pearson's correlation analysis was applied to estimate the correlation between root volume and dentoskeletal morphology. Both the central and lateral incisors had intrusion and tipping movement after treatment. Compared with pretreatment data, root length decreased significantly. The lingual root volume of root cervical, apical third, and the labial root volume of the root apical third decreased significantly (P < .05), among which the percentage of tooth loss at the tip volume was the highest. The pretreatment height of the alveolar ridge crest, thickness of the alveolar bone, and type of incisor movement were related to the volume and length loss. Volume and length loss in the apical third of the lower incisor roots in skeletal Class III patients treated with a Class III bicuspid extraction pattern is common. The pretreatment height of the alveolar ridge crest, thickness of the alveolar bone, and type of tooth movement are related to the loss.

Prevalence and morphological analysis of isthmuses in mandibular molars of the Indian population: A micro-computed tomographic study.

This study evaluated the prevalence, configurations, and correlation of isthmuses at coronal, middle, and apical root 3rd in mandibular molars of the Indian population using micro-computed tomography μCT). One hundred and five permanent mandibular molar teeth were scanned under μCT. The axial sections were analyzed at the coronal, middle, and apical thirds of the root for isthmus types and classified according to Hsu and Kim's classification. Descriptive statistics for each isthmus type were calculated. The correlations between the apical, middle, and coronal thirds of the root were determined using Pearson's correlation coefficient. Type IV isthmus was the most common in the coronal third of the mesial root of mandibular 1st molar (42.9%), while Type V was prevalent in the coronal third of the mesial root of 2nd molar (42.9%). Type I isthmus was found to be highly prevalent in the middle 3rd (71.4%) and apical 3rd (61.9%) of mesial roots of 1st molars, and in the middle 3rd (71.4%) and apical 3rd (42.9%) of mesial roots of 2nd molars. Type V isthmus was the most prevalent in all the thirds of the distal roots of both 1st and 2nd molars, ranging from 40% to 50%. Furthermore, a strong correlation of 0.965 (P < 0.01) was found between the isthmuses in the apical and middle thirds of roots. There are variations in the prevalence and type of isthmuses across different sections of the root, including the presence of atypical isthmuses. Micro-CT with high-resolution imaging and three-dimensional reconstruction is crucial for investigating root canal morphology. Clinicians could benefit from considering demographic characteristics to better predict the presence of isthmus variations. The isthmus configurations and frequency differ at each section of mandibular teeth.

Influence of different adhesion strategies on glass fiber post retention.

Failures in glass fiber post (GFP) retention may be associated with low adhesion achieved in root dentin. 55 single-rooted premolars were endodontically treated and distributed according to different adhesion strategies (n=11): G1: RelyX ARC (3M ESPE; etch-rinse strategy); G2: Relyx Ultimate (3M ESPE; etch-rinse strategy); G3: AllCem (FGM; etch-rinse strategy); G4: Relyx Ultimate (3M ESPE; self-etching strategy); G5: RelyX U200 (3M ESPE; self-adhesive strategy). For Bonding Strength (BS) analysis, the roots were sectioned in slices (1.0mm thickness) corresponding to each root third and submitted to push-out test. The type of failure was assessed by scanning electron microscopy (SEM). The highest BS averages were found in G2 and G3. However, in the middle and apical root thirds, G3 showed statistically similar results to G4 and G5. In the cervical and middle third, G1 was statistically similar to G4 and G5. The mixed type of failure was the most common in all groups. Self-etching (G4) and self-adhesive resin (G5) cements, showed similar BS results of immediate bonding in the cementation of GFP compared to conventional resin cements (G1, G2, G3). Key words:Dental Cements, Dentin-Bonding Agents, Post and Core Technique, Dental Bonding.

&lt;strong&gt;The effect of oligosaccharide chitosan irrigating agent on penetration of two type endodontic sealers into the dentinal tubules: a confocal laser scanning microscopy study&lt;/strong&gt;

ABSTRACTIntroduction: Irrigation during root canal treatment is one of the important factors that play a role in determining the quality of sealer penetration into the dentinal tubules, especially in the apical third of the tooth root. This is inseparable from the selection of the used irrigation agent. Currently, oligosaccharide chitosan has been developed which is easier to manipulate as an alternative irrigation agent. This study aimed to analyze the effect of the chitosan oligosaccharide irrigating agent on the penetration of two types of endodontic sealers into the dentinal tubules. Methods: This study used 60 mandibular premolars which were randomly divided into 3 groups (n=3). Group 1 was irrigated with 2% chitosan oligosaccharides; Group 2 with a combination of 2.5% NaOCl and 0.2% chitosan nanoparticles; and group 3 was irrigated with a combination of 2.5% NaOCl and 17% EDTA. At the time of obturation, each group was divided into two groups, for sealer treatment using CeraSeal Bioceramic and AH Plus sealer. The sealer’s penetration depth was measured using a confocal laser scanning microscope. Results: The highest mean on the penetration depth of the sealer was seen in the irrigation group using chitosan oligosaccharide solution with CeraSeal bioceramic sealer (2575,151 AU) (p&gt;0.05). Conclusion: There is an effect of 2% oligosaccharide chitosan solution on sealer penetration into dentinal tubules. CeraSeal bioceramic sealer showed better penetration than AH Plus sealer.Keywords: oligosaccharide chitosan; ceraseal bioceramic sealer; AH plus sealer; confocal laser scanning microscope

A Modern View of Human Tooth Roots Apical Morphology (Literary Data Analysis)

Many anatomical landmarks and their corresponding terminology can be found in the scientific and educational literature that characterize the apical third of tooth roots. They are often used in the subsequent description of the clinical situation to carry out treatment procedures and predict the outcome of the disease. The morphology of the apical third of the root canals has always been the subject of research. The use of electron-scanning and stereo microscopes in the study of the apical third have become a new challenge for both researchers and practicing dentists. This method of research allows not only to determine the location, shape, size and quantity of the anatomical hole, but also to characterize the morphology of the most hidden details of its lumen accurately. A study of the literature revealed that a number of studies have been devoted to the study of Intradont architectonics. At different times, apical thirds of different groups of teeth were examined under a scanning and stereo microscope in various countries. Our literature analysis revealed many interesting and mutually exclusive facts. Noteworthy is different (heterogeneous) terminology of the morphological elements of the apical part of the root, which complicates the theoretical understanding of the issue and its application in clinical practice. The abovementioned demonstrates not only the importance of conducting such research in Georgia and its need. However, studying the apical thirds of the tooth roots that will be the target of our future.

A Modern View of Human Tooth Roots Apical Morphology (Literary Data Analysis)

Many anatomical landmarks and their corresponding terminology can be found in the scientific and educational literature that characterize the apical third of tooth roots. They are often used in the subsequent description of the clinical situation to carry out treatment procedures and predict the outcome of the disease. The morphology of the apical third of the root canals has always been the subject of research. The use of electron-scanning and stereo microscopes in the study of the apical third have become a new challenge for both researchers and practicing dentists. This method of research allows not only to determine the location, shape, size and quantity of the anatomical hole, but also to characterize the morphology of the most hidden details of its lumen accurately. A study of the literature revealed that a number of studies have been devoted to the study of Intradont architectonics. At different times, apical thirds of different groups of teeth were examined under a scanning and stereo microscope in various countries. Our literature analysis revealed many interesting and mutually exclusive facts. Noteworthy is different (heterogeneous) terminology of the morphological elements of the apical part of the root, which complicates the theoretical understanding of the issue and its application in clinical practice. The abovementioned demonstrates not only the importance of conducting such research in Georgia and its need. However, studying the apical thirds of the tooth roots that will be the target of our future.

Development of Lipidic Nanoplatform for Intra-Oral Delivery of Chlorhexidine: Characterization, Biocompatibility, and Assessment of Depth of Penetration in Extracted Human Teeth.

Microorganisms are the major cause for the failure of root canal treatment, due to the penetration ability within the root anatomy. However, irrigation regimens have at times failed due to the biofilm mode of bacterial growth. Liposomes are vesicular structures of the phospholipids which might help in better penetration efficiency into dentinal tubules and in increasing the antibacterial efficacy. Methods: In the present work, chlorhexidine liposomes were formulated. Liposomal chlorhexidine was characterized by size, zeta potential, and cryo-electron microscope (Cryo-EM). Twenty-one single-rooted premolars were extracted and irrigated with liposomal chlorhexidine and 2% chlorhexidine solution to evaluate the depth of penetration. In vitro cytotoxicity study was performed for liposomal chlorhexidine on the L929 mouse fibroblast cell line. Results: The average particle size of liposomes ranged from 48 ± 4.52 nm to 223 ± 3.63 nm with a polydispersity index value of <0.4. Cryo-EM microscopic images showed spherical vesicular structures. Depth of penetration of liposomal chlorhexidine was higher in the coronal, middle, and apical thirds of roots compared with plain chlorhexidine in human extracted teeth when observed under the confocal laser scanning microscope. The pure drug exhibited a cytotoxic concentration at which 50% of the cells are dead after a drug exposure (IC50) value of 12.32 ± 3.65 µg/mL and 29.04 ± 2.14 µg/mL (on L929 and 3T3 cells, respectively) and liposomal chlorhexidine exhibited an IC50 value of 37.9 ± 1.05 µg/mL and 85.24 ± 3.22 µg/mL (on L929 and 3T3 cells, respectively). Discussion: Antimicrobial analysis showed a decrease in colony counts of bacteria when treated with liposomal chlorhexidine compared with 2% chlorhexidine solution. Nano-liposomal novel chlorhexidine was less cytotoxic when treated on mouse fibroblast L929 cells and more effective as an antimicrobial agent along with higher penetration ability.

Evaluación in vitro de la interacción entre el clorhidrato de lidocaína y las soluciones de irrigación en la dentina del conducto radicular: Un estudio con microscopio electrónico de barrido

Aim: To investigate the precipitate formed from the interaction between 2% lidocaine hydrochloride with adrenaline (LA) with 2.5% sodium hypochlorite (NaOCl) and 0.2% chitosan nanoparticles on root canal dentin, using scanning electron microscopy (SEM). Material and Methods: Sixty mandibular premolars were decoronated, and the root length standardised. The specimens were randomly distributed into the following groups: Group 1 (control): 2% LA mixed with sterile water without root canal instrumentation, Group 2: 2% LA with 2.5% NaOCl in water without root canal instrumentation, and Group 3: 2% LA with 0.2% chitosan nanoparticles in water without root canal instrumentation. Teeth specimens were split and subjected to SEM analysis at cervical, middle, and apical root thirds. On observing precipitate formation in Group 2, 10 premolars were decoronated and treated with 2% LA and 2.5% NaOCl and subjected to root canal instrumentation. Results: Group 1 and Group 3 showed patent dentinal tubules and no precipitate formation. Group 2 showed precipitate blocking dentinal tubules in all the three sections, and the precipitate could not be removed completely after cleaning and shaping. Conclusion: NaOCl forms an insoluble precipitate on interaction with local anaesthetic solution that cannot be removed after chemo-mechanical preparation. Chitosan nanoparticles do not form any such precipitate and show patent dentinal tubules. Hence, chitosan can be used as a flushing irrigant.

Factors associated with the eruption of the impacted maxillary third molars after second molar extraction

In orthodontic treatment, the space left after extracting the maxillary second molar (MxM2) may be filled by the eruption of the impacted third molar (MxM3). However, little is known about the factors associated with the eruption of the impacted MxM3. We aimed to characterize the clinical factors associated with the time taken for MxM3 eruption after MxM2 extraction. We analyzed factors associated with late MxM3 eruption (>500 days after MxM2 extraction) in 84 molars. Prespecified risk factors were entered into logistic regression models to estimate odds ratios (ORs). The median duration between MxM2 extraction and MxM3 eruption was 302 days (interquartile range, 140-424). Significant factors associated with late MxM3 eruption included the proximity of the MxM3 root to the maxillary sinus floor (OR, 51.72), the distance between the occlusal plane of the MxM3 and the apical third of the MxM2 roots (OR, 16.56), MxM3 angulation and depth of ≥20° (OR, 5.58), ANB angle of<2° (OR, 9.05), and ≥1.5 mm distal movement of the maxillary first molar (MxM1) from its original position at the time of MxM2 extraction and MxM3 eruption (OR, 12.9). The probability of late MxM3 eruption was 0% (0 out of 30) with no risk, 6.9% (2 out of 29) with 1 risk factor, and 52% (13 out of 25) with ≥2 risk factors. We identified 5 clinical factors associated with late MxM3 eruption after MxM2 extraction. The probability of late MxM3 eruption increased as the number of present risk factors increased. These findings can be used for risk stratification during orthodontic treatment.

Evaluation of rotary instruments with whipping motion in the biomechanical preparation of large root canals of young permanent teeth.

Shaping ability evaluation of taper ./01 instruments in large root canals, by microcomputed tomography (micro-CT) and scanning electron microscopy (SEM). Maxillary central incisors with large diameter root canals were divided into two groups (n=10): XP-Endo Shaper (FKG-Dentaire, Switzerland) and manual instrumentation (FKG-Dentaire). Two- and three-dimensional parameters from cervical to apical root thirds were evaluated by micro-CT. Apical stop was evaluated by SEM images. Data were analysed by ANOVA and Tukey tests (α=5%). XP-Endo Shaper allowed a regular biomechanical preparation with less dentinal wear compared with manual instrumentation, which showed excessive wear of the thin root canal walls (p < 0.05). Roundness and SMI showed similarity between both protocols (p > 0.05). XP-Endo Shaper SEM showed a regular and well-defined shape of the apical foramen suggesting the formation of the apical stop. Reduced diameter and taper instruments promoted a conservative wear and a well-defined apical stop formation in large root canals.

Impact of agitation/activation strategies on the antibiofilm potential of sodium hypochlorite/etidronate mixture in vitro

BackgroundTo investigate the effect of a rotary agitation method or ultrasonically activated irrigation on the antibiofilm effect of a mixture of sodium hypochlorite (NaOCl) and etidronate (1-hydroxyethylidene-1,1-bisphosphonate, HEBP) using a dual-species biofilm model in root canal system.MethodsMature dual-species biofilms of Enterococcus faecalis and Streptococcus gordonii were formed in root canals of mandibular premolars. Teeth were randomly allotted (n = 12) to group 1, XP-endo Finisher (XPF); group 2, ultrasonically activated irrigation (UAI); group 3, syringe-and-needle irrigation (SNI). In all groups, canals were instrumented with a rotary instrument (XP-endo Shaper) prior to irrigant agitation/activation. A mixture containing 2.5% NaOCl and 9% HEBP was used throughout the experiment. Bacterial counts from the canal were determined using qPCR before preparation (S1), after preparation (S2), and after final irrigation agitation/activation (S3). Bacterial viability within the dentinal tubules in the coronal, middle and apical root-thirds was quantified using confocal microscopy after Live/Dead staining. The bacterial counts and viability were compared between groups using one-way ANOVA and post-hoc Tukey’s tests. Paired t-test was used to compare the bacterial counts within groups.ResultsInstrumentation alone could significantly reduce the microbial counts in all the groups (P < 0.0001). Subsequent agitation/activation resulted in significant microbial reduction only in XPF and UAI (P < 0.05), both of which reduced significantly more microbial counts than SNI (P < 0.05). Live/Dead staining revealed that XPF and UAI showed significantly greater percentage of dead bacteria within the dentinal tubules than SNI in the coronal third (P < 0.05); UAI resulted in the significantly highest percentage of dead bacteria in the middle third (P < 0.05); while there was no significant difference between the groups in the apical third (P > 0.05).ConclusionsWhen using the sodium hypochlorite/etidronate mixture for irrigation, final irrigant agitation/activation with XP-endo Finisher or ultrasonic can improve disinfection of the main root canal space and the dentinal tubules in the coronal third, while ultrasonically activated irrigation appears to exhibit better disinfection within dentinal tubules in the middle third.

Evaluation of the band-shaped isthmuses in the mesiobuccal root canal system using micro-computed tomography.

This micro-computed tomography (micro-CT) study analyzed band-shaped isthmuses having their floor at the apical third of the mesiobuccal roots of maxillary molars in terms of 2D and 3D morphological parameters. A total of 199 maxillary first molars were scanned with micro-CT. Twenty-seven specimens, confirmed to have a band-shaped isthmus, were further examined in terms of the isthmus length, volume, structure model index (SMI), and surface area. The distance of apical foramina of mesial canals from the isthmus floor and major-minor diameters, roundness, perimeter, and area of the isthmus roof and floor were compared. Statistical analyses were performed with descriptive statistics and t-test with a 5% significance threshold. The band-shaped isthmus frequency was 13.5% and its length reached up to 5.5mm. The distances of the apical foramina of mesiobuccal canals (MB1 and MB2) from the isthmus floor were similar (p > .05). Isthmus roof and floor showed significant differences in terms of their major diameter and area (p < .05), whereas their minor diameter, roundness, and perimeter values were similar (p > .05). The band-shaped isthmuses are not rare and can reach through the half of the root length with oval cross-sections in the floor and roof anatomy. The distance between the isthmus floor and apical foramina did not differ between MB1 and MB2. The band-shaped isthmus morphology contributes to the complexity of the apical anatomy of maxillary first molar teeth with various lengths and diameters.

A micro-CT analysis of radicular dentine thickness in mandibular first premolars presenting C-shaped root canals: Identification of potential danger zones.

To describe the radicular dentine thickness in mandibular first premolars presenting C-shaped root canals, to identify the canal walls with less thickness as potential danger zones. In addition, to describe the internal and external anatomical characteristics of these teeth and associate them with the dentine thickness. A total of 70 mandibular first premolars presenting C-shaped root canals were examined. Their internal morphology was analysed using Vertucci's and Fan's criteria, and their external morphology was analysed using the ASUDAS score. Besides, the dentine thickness around the root canals was two/three-dimensionally determined at five root planes and quantified in the distal and the mesial aspects. According to Fan's, ASUDAS, and Vertucci's classifications, the most common canal configurations were category C3, grade 3, and type V, respectively. In Vertucci's type III anatomy, the mesial root wall of the lingual canal showed significantly less dentine thickness than the distal wall in the middle plane (p=.031). Similarly, in Vertucci's type V anatomy, significantly less dentine thickness was observed in the mesial root wall of the buccal and lingual canals in the middle plane (p<.001) and the buccal canal in the middle-apical plane (p=.014) than the distal root wall of these canals. In teeth with ASUDAS grade 3 and 4 scores, significantly less dentine thickness was observed in the mesial in comparison with the distal root wall of these canals. These differences were demonstrated in the middle and middle-apical planes (p<.001) of grade 3 teeth and the middle-apical plane (p<.001) of grade 4 teeth. In these root planes, the Ver1-AS3 and VerV-AS3 combinations presented a 4-times greater risk of presenting walls with a critical dentine thickness of 0.6mm (odds ratio [OR]=4, p=.025) than the combinations Ver1-AS2, VerV-AS2, VerV-AS4, and VerIII-AS3. The root canal system configuration of mandibular first premolars with C-shaped canals showed a wide range of anatomical variations. The lowest dentine thickness was located in the mesial wall of the canals in the middle and apical root thirds of Vertucci's type III and V anatomies and in teeth with deep radicular grooves scored as ASUDAS grades 3 and 4. In the middle and middle-apical planes, the presence of the combinations Ver1-AS3 and VerV-AS3 showed a high risk of presenting a critical dentine thickness of 0.6mm. Therefore, these root canal walls with less dentine thickness represent potential instrumentation danger zones in mandibular first premolars with C-shaped canals.

Comparative evaluation of root canal dentin erosion after using different smear layer removing solutions for root canal irrigation by scanning electron microscope (SEM) and energy dispersive x-ray spectroscopy (EDS): An in-vitro study

Objective: To evaluate and compare the effect of different final irrigating solutions (17% EDTA, Smear Clear, QMix and BioPure MTAD) on root canal dentin erosion in the coronal, middle and apical third of root by Scanning Electron Microscope (SEM) and Energy Dispersive Spectroscopy (EDS). Materials and Methods: A total of 105 recently extracted mandibular premolars were taken and decoronated to a standardized root length of 12mm. They were prepared using ProTaper system up to size F3. Initial rinse was done with sodium hypochlorite. After completion of root canal preparation, all root canals were subjected to final irrigation protocol. Group 1 was irrigated with 17% EDTA for 1 min. Group 2 was irrigated with Smear Clear for 1 min. Group 3 was irrigated with QMix for 1 min. Group 4 was irrigated with MTAD for 5 min. Group 5 was irrigated with distilled water. Out of 21 samples in each group, 10 were analysed by SEM and 11 were analysed by EDS. Results: The results of the SEM analysis revealed that the use of 17% EDTA and Smear Clear resulted in significantly more erosion than the use of QMix and MTAD. No statistically significant difference was observed at the coronal, middle and apical thirds in the amount of dentin erosion. The results of EDS analysis revealed that all treatment groups significantly decreased calcium content in comparison to control group. However, no significant difference was observed among EDTA, Smear Clear, Qmix and MTAD in decreasing calcium levels in dentin. Conclusion: BioPure MTAD and QMiX cause negligible dentin erosion and thus can be used as alternative final irrigating solutions after sodium hypochlorite instead of EDTA and Smear Clear.