Middle Root Research Articles

Scanning electron microscopic analysis of interaction between 2% lidocaine hydrochloride (with adrenaline) with 3% sodium hypochlorite and 2% chlorhexidine on root canal dentin after Chemomechanical instrumentation: An in vitro study

Introduction: To investigate the effect of resultant precipitate formed on interaction between 2% lidocaine hydrochloride (with adrenaline) (LA) with 3% sodium hypochlorite (NaOCL) and 2% chlorhexidine (CHX) on root canal dentin after chemomechanical preparation using scanning electron microscopy (SEM). Methods: Thirty six mandibular premolars were decoronated, and the root length was standardized. All specimens were randomly distributed into the following three groups: Group I (control): 2% LA mixed with sterile water. Group II: 2% LA with 3% NaOCL, Group III: 2% LA with 3% CHX. In all groups mechanical instrumentation with rotary files was done. Teeth samples were sectioned into three parts, split and SEM analysis of root canal wall was done at cervical. Middle, and apical root thirds. Results: SEM images revealed patent dentinal tubules with no precipitate occlusion in group I and group III, whereas there was occlusion of dentinal tubules with a precipitate in group II at all the three root levels studied. Conclusions: The precipitate formed on the interaction between 2% LA solution with 3% NaOCL tends to occlude the dentinal tubules at the coronal, middle, and apical root thirds. The chemomechanical rotary instrumentation procedure did not effectively remove the precipitate from all the three root levels of the specimens studied. LA/sterile water group and LA/CHX group did not result in any precipitate formation on root canal dentin.

Assessment of hybridization and push out bond strength of fiber post after endodontic retreatment. An invitro study

Objective: The aim of this study was to assess hybridization and push out bond strength of fiber post after endodontic retreatment. Materials and methods: 10 freshly extracted human canines were collected having single root canal, samples were decoronated. Endodontic treatment was made to all samples. Samples were inserted into resin blocks. Then randomly divided in to: group I (control group) (5n) drilling to prepare post space followed by post cementation using total etch cement; while in group II (retreatment group) (5n) endodontic retreatment was made followed by drilling and post cementation as group one. Samples were sectioned into six sections of 1.5 mm thickness. Push-out test was performed using universal testing machine. Scanning of the root interface was made by SEM. Results: Group I showed significantly higher mean push-out bond strength (11.55 MPA) than Group II (7.93 MPA). Coronal (13.13 MPA) and middle root levels (9.62 MPA) showed significantly higher mean push-out bond strength than apical level (6.48 MPA). GI showed significantly higher mean push-out bond strength (16.06 MPA) than GII (10.19 MPA) at coronal level. At middle and apical levels; there were no significant difference. SEM showed resin tags and hybridization within dentin in GI while in GII there was an ill-defined hybrid layer at interface. Conclusions: Endodontic retreatment showed significant adverse effect on fiber post push-out bond strength. Root level affected fiber post push-out bond strength only in endodontically treated teeth. Interface of the endodontically treated teeth showed hybrid layer while in endo-retreatment gaps and void were seen.

Push-out Bond Strength of Two Types of Dental Post Luted with Two Types of Cement at Two Different Root Levels.

ObjectiveEndodontically treated teeth may require posts for retaining the core and replacing the coronal structures that have been lost. The objective of this study was to evaluate and compare the push-out bond strength between different types of post cemented with different types of luting cement at different types of root level.Materials and MethodsIn this in-vitro study, a total of 48 single-rooted permanent human teeth were decoronated, and the roots were treated endodontically. Following post space preparation, the sample was divided into four groups (n= 12 each) based on the types of post and cement. Two different types of post [GC everStick®POST (ES) and Parapost® Fiber LuxTM (PF)], and two different types of cement [G-CEMTM (G), and RelyXTM Unicem (R)] were used according to the manufacturer’s instructions. All roots were sectioned at the coronal and middle thirds with a thickness of 3±0.1mm. The Push-out bond strength (PBS) test was performed using a universal testing machine at a cross-head speed of 0.5mm/ min. The bond strength values were recorded, and the data were analyzed using the SPSS program. Apart from descriptive statistics, three-way ANOVA was used for the interaction of the independent variables (post, cement, and root level). For differences between the groups, the Mann-Whitney U test was used. A P-value of less than 0.05 was considered significant for all analyses.ResultsPush-out bond strength of samples at the middle level (11.38±10.31 MPa), with PF posts (11.18±9.98 MPa), and of those luted with RelyXTM Unicem cement (13.26±8.73 MPa) was higher than that of their counterparts. The PBS means of RelyXTM Unicem cement at both root levels were much higher than PBS means of G-CEMTM cement. Three-way ANOVA test revealed a significant effect for each variable with a higher effect of cement (Sum of Squares= 1310.690; P< 0.001). No significant difference (P= 0.153) was found between the coronal and middle parts and between ES and PF posts (P= 0.058). However, a highly significant difference (P< 0.001) was found between RelyXTM Unicem and G-CEMTM cements.ConclusionThe type of cement had a significant effect on push-out bond strength with RelyXTM Unicem which had higher values than G-CEMTM. However, the type of post and root level had no significant effect on PBS, although Parapost® Fiber LuxTM and middle root level had higher values than their counterparts.

Comparison of dentin penetration ability of different root canal sealers used with different obturation methods.

This in vitro study aimed to investigate the tubular penetration depth of four different sealers used with two different obturation methods in the apical, middle, and coronal root canal dentin. Eighty-four single-rooted teeth were instrumented until the F4 ProTaper universal rotary file and filled with AH26, AH Plus (Dentsply, DeTrey, Konstanz, Germany), RealSeal (SybronEndo, Orange, CA), and MTA Fillapex (Angelus, Londrina, Brazil) using cold lateral condensation (CLC) and single-cone (SC) obturation techniques. Thereafter, the roots were sectioned longitudinal and prepared for scanning electron microscope evaluation. The maximum and minimum sealers penetration depth into dentinal tubules at the apical, middle, and coronal regions and the average depth of sealer penetration were calculated. The data was statistically analyzed two-way ANOVA and post hoc Tukey and Dunnett tests and independent samples t test using maximum mean values. There was no statistically difference between the obturation methods (p > .05). When the sealers are evaluated within themselves AH26 was affected by obturation methods significantly (p < .05). Also the results revealed a significant difference between root regions (p < .05). AH26 and RealSeal root canal sealers had the highest penetration values with CLC and SC obturation techniques, respectively. The obturation method did not affect the penetration amount of root canal sealers. RealSeal root canal sealer performed better penetration ability than the other sealers. Apical third of the root in all groups showed lowest penetration depth.

Effect of Hydrogel-Based Antibiotic Intracanal Medicaments on Push-Out Bond Strength.

Objective This study aimed to evaluate the effects of typical clinical concentration (1,000 mg/mL), low concentration (1 mg/mL) triple antibiotic pastes (TAP), and double antibiotic pastes (DAP) on the bond strength between various root cements and radicular dentin. Materials and Methods Intact single-rooted human teeth ( n = 144) were horizontally decoronated and canals instrumented. The roots were treated for 4 weeks with Ca(OH) 2 , 1,000 mg/mL of TAP or DAP, and 1 mg/mL of TAP or DAP. Untreated roots served as a control. After treatment, the medicaments were irrigated and each group was divided into three subgroups receiving MTA, Biodentine, or Endosequence putty cement. After 2 weeks, coronal and middle root cylinders were obtained from each root. Push-out bond strength test and failure analysis were performed for all root cylinders. Statistical Analysis Three-way ANOVA, pairwise comparisons and logistic regression were used for statistical analyses. A significance level of 5% was used. Results For MTA applied in the coronal part of the roots, 1 mg/mL DAP and TAP and Ca(OH) 2 demonstrated significantly higher bond strength compared with the typical clinical concentration and the control groups. For Biodentine applied coronally in the roots, 1 mg/mL of DAP resulted in significantly higher bond strength than all other groups. For Endosequence putty cement applied coronally in the roots, 1 mg/mL of DAP offered significantly higher bond strength than all groups except for Ca(OH) 2 . Conclusion The use of 1 mg/mL DAP resulted in significantly higher push-out bond strength compared with the typical clinical concentration of TAP and DAP regardless of the type of the root cement used.

Nanobubble-Enhanced Antimicrobial Agents: A Promising Approach for Regenerative Endodontics

IntroductionIn this study, we investigated the properties of nanobubble (NB) water and its effect on smear layer removal and strengthening the efficiency of disinfecting agents used in regenerative endodontic treatment. MethodsNB water was generated in a NB Generator. The NB size, concentration, and pH were measured. Porcine teeth were enlarged to size 60 by using hand-files and irrigated with either NB water or 17% EDTA or received no further irrigation. The ability of irrigants to remove the smear layer was evaluated by using a scanning electron microscope (9 roots/group). Other samples (6 roots/group) were subjected to Vickers hardness test to determine the dentin microhardness. Autofluorescent tetracycline mixed with distilled water or NB water was placed inside the root canal space of porcine teeth, and the depth of medicament penetration into the dentinal tubules was visualized by using fluorescent stereomicroscope (5 roots/group). For the disinfection experiment, human roots were prepared, autoclaved, and inoculated with Enterococcus faecalis for 3 weeks. Canals were then disinfected by (1) standard needle irrigation (SNI) with 5.25% NaOCl, (2) 5.25% NaOCl with ultrasonication (US), (3) 5.25% NaOCl + XP finisher (XP), (4) SNI with 1.5% NaOCl, or (5) SNI with 1.5% NaOCl in NB water (5 roots/group). Teeth were split open and stained with LIVE/DEAD BackLight and visualized by using confocal laser scanning microscope (CLSM) at the coronal, middle, and apical thirds of the canal. The ratio of dead/total bacteria in the dentinal tubules at various depth levels (50, 100, and 150 μm) was calculated. ResultsNB water was more effective in removing smear layer than 17% EDTA and could allow infiltration of tetracycline into the dentinal tubule more than 1 mm. NB water did not alter the dentin microhardness compared with 17% EDTA (P < .05). At 50-μm depth, CLSM analysis showed no statistically significant difference between 1.5% NaOCl in NB water and 5.25% NaOCl with or without irrigation activation at the coronal, middle, and apical root segments (P > .05), ie, these groups had stronger bacterial killing than 1.5% NaOCl (P < .05). At deeper levels (100 and 150 μm), higher concentrations of NaOCl were more effective than 1.5% NaOCl with or without NB water. No statistically significant difference was noted between 5.25% NaOCl with and without irrigation activation at most depth levels (P > .05). ConclusionsNB water can allow smear layer removal and enhance tubular penetration of medicaments without changing dentin microhardness. In large canal models, NB water appears to improve the tubular disinfection capacity of lower concentration of NaOCl up to 50 μm. On the other hand, the use of irrigation activation (US or XP) did not provide any added disinfection into the dentinal tubules compared with SNI. These results suggest that NB water may be a promising adjunct to endodontic irrigants and medicaments.

PREVALENCE OF SUPERNUMERARY ROOTS OF PERMANENT MANDIBULAR TEETH ACCODING TO CONE-BEAM COMPUTED TOMOGRAPHY STUDY

1800 pre-made cone beam computed tomograms (CBCT) were examined, of which 202 CBCT were selected. It was revealed that a prevalence of three-rooted mandibular first molar was 2,5 %, second molars - 4,5 %. First molar supernumerary root was always distolingual root (radix entomolaris). Second molar supernumerary root was distolingual root in 2,5 % (radix entomolaris), in 2 % mesialbuccal root (radix paramolaris)., The prevalence of double-root in the mandibular first premolar was 2 %, in the second premolar was 1 %, in the mandibular canines was 5 %, the bifurcation was located in the apical and middle third root canals of canine and premolar, which makes endodontic treatment of such teeth as difficult as possible.

A Comparative Evaluation of Gutta-Percha and Sealer Removal of Rotary Niti File Retreatment Systems

Forty lower premolars with single root canals prepared with ProtaperNext files to size 25, and obturated with GP/sealer using lateral compaction. Teeth divided randomly into four groups (group n=10). Protaper universal retreatment kit (PUR), D-Race desobturation files (DRD), R-Endo retreatment kit (RE) and Hedstrom (H) files (control) were used to remove GP/sealer in each group. Removal effectiveness assessed by measuring the GP /sealer remnants in the roots after sectioning them into two halves. Stereomicroscope with a digital camera used to capture digital images. Images processed by ImageJ software to measure the percentage of GP/sealer remnants surface area in total, coronal, middle and apical areas of the canal. In the coronal area, PUR had significantly lower R% than RE and H groups, respectively (p 0.05), as well as no significant difference between RE and H groups(p>0.05). In the middle, apical and total root areas, Both PUR and DRD had significantly lower R% than RE and H groups, respectively (p 0.05). Also, there was no significant difference in R% between RE and H groups (p>0.05).

Zn/Cd status-dependent accumulation of Zn and Cd in root parts in tobacco is accompanied by specific expression of ZIP genes

BackgroundRoot-to-shoot translocation of zinc (Zn) and cadmium (Cd) depends on the concentrations of both metals in the medium. A previous study on tobacco (Nicotiana tabacum) pointed to the contribution of NtZIP1, NtZIP2, NtZIP4 and NtIRT1-like in the regulation of this phenomenon. To learn more, Zn and Cd accumulation, root/shoot distribution and the expression of ZIP genes were investigated in the apical, middle and basal root parts.ResultsWe show that Zn/Cd status-dependent root-shoot distribution of both metals was related to distinct metal accumulation in root parts. At low Zn and Cd in the medium, the apical part contained the highest metal level; at higher concentrations, the middle and basal parts were the major sink for excess metal. The above were accompanied by root part-specific expression pattern modifications of ZIPs (NtZIP1-like, NtZIP2, NtZIP4A/B, NtZIP5A/B, NtZIP5-like, NtZIP8, NtZIP11, NtIRT1, and NtIRT1-like) that fell into four categories with respect to the root part. Furthermore, for lower Zn/Cd concentrations changes were noted for NtZIP5A/B and NtZIP5-like only, but at higher Zn and Cd levels for NtZIP1-like, NtZIP5-like, NtZIP8, NtZIP11, NtIRT1, and NtIRT1-like. NtZIP1, here renamed to NtZIP5B, was cloned and characterized. We found that it was a zinc deficiency-inducible transporter involved in zinc and cadmium uptake from the soil solution primarily by the middle root part.ConclusionsWe conclude that regulation of the longitudinal distribution of Zn and Cd is highly specific, and that the apical, middle and basal root parts play distinct roles in Zn/Cd status-dependent control of metal translocation efficiency to shoots, including the stimulation of Zn translocation to shoots in the presence of Cd. These results provide new insight into the root part-specific unique role of NtZIP5B and other ZIP genes in the longitudinal distribution of zinc and cadmium and their contribution to the regulation of root-to-shoot translocation.

Soil water dynamics in the active layers under different land-cover types in the permafrost regions of the Qinghai–Tibet Plateau, China

The mechanisms of hydrological processes, biochemical cycles, and permafrost revolution, and the potential impacts of climate change on these, are still poorly quantified in alpine regions, partly due to a lack of understanding of soil water dynamics in the permafrost active layer. In this study, soil water in the active layer was monitored in-situ at nine sites, including wet meadow (WM), alpine meadow (AM), alpine steppe (AS), transitional area-steppe (TA-S), transitional area-meadow (TA-M), bare land (BL), extremely degraded wet meadow (EDWM), alpine steppe on south-facing slope (ASSF), and alpine meadow on north-facing slope (AMNF) regions. These sites are located in the hinterland of the Qinghai–Tibet Plateau (QTP). Ground-ice distributions and isotope variations under different alpine ecosystems were also examined. The results demonstrate that soil water content was low at 0.5-m depth and high at the surface and at 1.0-m depth in the soil profiles from the TA-S, BL, EDWM, ASSF, and AMNF sites. However, denser vegetation coverage masked the effects of the freeze–thaw processes, which leading soil water content increased gradually with soil depth. Moreover, rainfall infiltration for recharging soil water in the lower layers was hampered due to the buffering action of mattic epipedons and the existence of clayed layers. Additionally, preferential flow often occurred in the degraded alpine meadows, which supplied deeper soil water. The Pearson correlation coefficients between soil water in the deeper layers and ground-ice were above 0.67 (significance <0.05), suggesting that deep soil water had a stronger effect on the formation of ground-ice near the permafrost table than soil water at the surface and middle root layers. Furthermore, results from the analysis of isotopic tracers suggest that precipitation directly recharged more ground-ice near permafrost table at the EDWM, ASSF, and AWNF sites, but less so at the WM, AM, AS, and BL sites, due to greater evapotranspiration and land cover. These results provide insights into the effect future climate warming can have on ecological succession and regional hydrological processes.

EFFECTS OF MTAD ON THE BOND STRENGTH OF BIOCERAMIC ROOT CANAL SEALER

Aim: The aim of this in-vitro study was to investigate the effects of MTAD (a mixture of doxycycline, citric acid, and a detergent) on the bond strength of AH Plus (Dentsply DeTrey GmbH, Konstanz, Germany) and EndoSequence BC sealer (Brasseler USA, Savannah, Georgia, USA). Materials &amp; Methods: Eighty-four decoronated single-rooted human incisor teeth were prepared with Reciproc R25 files (VDW, Munich, Germany), and the canal was irrigated with 5 mL 1.3% NaOCl. The roots were randomly assigned to four groups (n = 21), according to the final irrigation protocol and sealer selection: Group 1: distilled water-AH Plus; Group 2: distilled water-EndoSequence BC; Group 3: MTAD-AH Plus; Group 4: MTAD-EndoSequence BC. For the final flush, in Groups 1 and 2, the root canals were irrigated with 5mL of distilled water; in Groups 3 and 4, 5mL of MTAD was used for 1 minute. After root canal obturation, specimens was embedded in an acrylic block and sectioned horizontally at three levels (coronal, middle, apical). Bond strength of sealer to root canal dentin was assessed via push-out test using a universal testing machine. Results: There were no significant differences among the groups in coronal and apical thirds. In the middle root third, Group 4 showed significantly lower push-out bond strength values than Group 2 (p=0.023). No significant difference was found between the two root canal sealers. Conclusions: Overall, MTAD final irrigation caused lower push-out bond strenght values than distilled water with no significancy.

Efficacy of Apple vinegar as Final Irrigating Solution in Removing Smear Layer Using XP-Endo Finisher File

Purpose: This study was assessed the efficacy of Apple vinegar as final irrigating solution in removing smear layer using XP-Endo Finisher File by scanning microscope. Material and Methods: Fifty single rooted lower premolars were selected and prepared using Universal ProTaper rotary files. Samples were divided into two main groups (I,II) regarding the final rinse used (20 samples each) and control group (10 samples): Group I: rinsed with 17% EDTA, Group II: rinsed with Apple vinegar and Control group: irrigated with sterile saline. Each group was subdivided into two subgroups (A,B) regarding the agitation file. Subgroup A: Conventional irrigation, Subgroup B: agitated with XP Endo Finisher. Samples were grooved longitudinally and smear layer was assessed. Results: no statistically significant difference in the median scores of smear layer produced by 17% EDTA and Apple Vinegar at coronal, middle and apical root levels when conventional irrigation or XP Endo Finisher were used. There was a significant difference between two irrigating techniques at apical level when 17% EDTA used as final rinse, where XP Endo Finisher showed statistically significant lower median score (P≤ 0.05). Conclusions: Apple vinegar presented similar smear layer removal efficiency from intraradicular dentin compared to 17% EDTA when used as final rinse. XP-Endo Finisher is a successful agitation system for removal of smear layer from intraradicular dentin.

Chitosan: A natural substitute of EDTA solution for final irrigation in endodontics treatment.

The purpose of this study was to assess the quantity of the chelated calcium ions and the smear layer removal efficiency after root canal final irrigation with three different solutions. Forty-five teeth were instrumented with rotary-files, then randomly divided into 3 equal groups (n = 15) depending on the final irrigation solution; group I: 17% ethylenediaminetetraacetic acid (EDTA), group II: 0.2% chitosan, and group III: 10% trisodium citrate. According to the time of application, every group was divided into 3 subgroups (1 min, 5 min, and 24 h). The quantification analysis of chelated calcium ions was performed by flame atomic absorption spectrometry (FAAS). Then, the presence of smear layer was examined by splitting the samples longitudinally and using scanning electron microscopy (SEM) to examine coronal, middle, and apical root canal levels. One-way analysis of variance (ANOVA) test was used for the evaluation of treatment effect. Kruskal-Wallis test was executed to detect a significant difference between groups, while Mann-Whitney U test has determined the difference between each two groups for smear layer. Both 17% EDTA and 0.2% chitosan had not been statistically significant difference for smear layer removal efficiency and observed calcium ion concentrations. Although, they were more efficient of 10% trisodium citrate with a significant difference (P < 0.05). The application time of the chelators' solutions must not exceed 5 min to completely remove smear layer, and 0.2% chitosan is a natural substitute for 17% EDTA with a safety application for 24 h.

Effect of calcium hydroxide intracanal medicament on the push-out bond strength of RelyX Unicem self-adhesive cement

Aim: This study was aimed to determine the use of calcium hydroxide (Ca(OH)2) intracanal medicament effect on the push-out bond strength of RelyX Unicem self-adhesive cement onto the root canal wall. Materials and Methods: A total of 50 extracted human maxillary permanent incisor teeth were randomly divided into control and experimental groups (n = 25 for each group). The control group was prepared for routine root canal treatment followed by post space preparation. RelyX Unicem self-adhesive cement is used for the cementation of fiber post in the root canal, as in experimental group, Ca(OH)2intracanal dressing was placed into the root canal for a week, followed by root canal filling, post space preparation, and cementation of fiber post using RelyX Unicem cementation. Each sample was divided into coronal, middle, and apical root sites. They were horizontally sliced and examined using scanning electron microscope (SEM). Three slices from each of the three sites were subjected to push-out test for bond strength measurement. Independent t-test was used to compare the push-out bond strength of RelyX Unicem on the root canal wall. One-way analysis of variance and pairwise comparison test were used for the statistical analysis. The significant level was set as P Results: The significant differences in bond strength were demonstrated between the different sites of the root, where the coronal and apical with the P value 0.031 and 0.020, respectively. However, the middle third of the root showed no statistically significant difference, where P = 0.072. Conclusions: Intermediate Ca(OH)2dressing has an effect on the bond strength of RelyX Unicem self-adhesive resin cementation on the root canal wall.

Root cryopreservation to biobank medicinal plants: a case study for Hypericum perforatum L.

In this study, an effective root-based cryopreservation method was developed for Hypericum perforatum L., an important medicinal species, using in vitro plants. A systematic approach was applied to determine effective combinations of protocol steps such as preculture, osmoprotection, vitrification solution treatment, and unloading, followed by protocol optimization using a single-factor approach. The effects of root section type (root tips, middle sections, or basal sections), duration of root section culture after excision, and donor plant age were also investigated. In a wild genotype, middle and basal root sections excised from 8-wk-old plants and cryopreserved at the age of 10 d after excision showed the highest plant regrowth after cryopreservation. In the optimized protocol, root sections were precultured in 10% (w/v) sucrose for 17 h, osmoprotected with a solution composed of 17.5% (w/v) glycerol and 17.5% (w/v) sucrose for 20 min, followed by a vitrification solution of 40% (w/v) glycerol and 40% (w/v) sucrose for 30 min, and cryopreserved using aluminum foil strips (droplet-vitrification). After rewarming in preheated 25% (w/v) sucrose solution and 30-min unloading, root segments were recovered on medium supplemented with 1.0 mg L−1 gibberellic acid and showed 78% plant regrowth. This cryopreservation method was successfully adapted for five elite lines of H. perforatum with a 45 to 87% regrowth rate after cryopreservation. These results suggest that root cryopreservation may be an effective method for medicinal plant conservation and should be tested with a broader range of species.

Evaluation of Chelating Potential of Chitosan Citrate and Chitosan Acetate on Intraradicular Dentin

Purpose: This study was designed to evaluate the chelating potential of chitosan citrate and chitosan acetate on intraradicular dentin using (ESEM) and quantity calcium content of intraradicular dentin using (EDX). Materials and Methods: sixty freshly extracted human single rooted lower premolars with single canal were instrumented with Revo-S files till size AS 35. The samples were divided into 5 experimental groups according to the final rinse used and control group (10 samples each); Group I: irrigated with 0.2% chitosan acetate, Group II: irrigated with 0.2% chitosan citrate, Group III: irrigated with 1% acetic acid, Group IV: irrigated with 1% citric acid, Group V: irrigated with 17% EDTA and control group which was divided into;(VIa) :5 samples irrigated with sterile saline and (VIb): 5 samples were neither prepared nor received any treatment. The cleanliness of the root canals and smear layer were evaluated at three root levels using ESEM. The calcium content of five samples from each experimental group (I,II,III,IV,V) and the samples of control group was measured using EDX. Results: At the coronal, middle and apical root levels; there was a statistical significant difference among the tested groups and the control . Regarding calcium content, the highest mean calcium content was recorded in samples treated with saline followed by samples that did not receive any irrigation Conclusion: The chelating potential of 0.2% chitosan acetate and 0.2% chitosan citrate is comparable to that of 17% EDTA when used as final rinse without much altering the calcium content.

Impact of fractured file removal from the middle third root canal on vertical root fracture resistance: three-dimensional finite element analysis

Objective: To analyze effect of fractured file removal from the middle third root canal on root fracture resistance using finite element analysis, which provides a theoretical basis for clinical prognosis evaluation. Methods: Two finite-element models were established, the fractured file removal model (fractured file located in the middle third of root canals, followed by ultrasonic file removal and root canal preparation) and the control model (root canal preparation only), and compressive displacement dependencies on compressive force was computed and compared with experimental data for validation. The validated finite-element models were used to analyze the stress distribution differences during the initiation, propagation and completion of the crack between fractured file removal specimen and control one. Results: The critical breaking force of the fractured file removal specimen was 406 N, and the finite element simulation result was 396 N. The critical breaking force of the control specimen was 502 N, and the finite element simulation result was 483 N. The position of crack initiation in the finite element simulation was basically consistent with that in the experiment. The experimental data of compressive test and the results of finite-element computation were in agreement, thus validating the finite-element model. In the process of continuous pressure, the stress distribution of the control root is relatively uniform, and the location of crack initiation and the direction of propagation have a certain unpredictability. Compared with the control root, the stress concentration on the root with fracture file removal was obvious, especially on edges, and the number of cracks are much more. Because of the thinner radicular wall, the crack propagation rate is faster too. Therefore, the overall root fracture resistant is decreased obviously. Conclusions: During the fractured file removal procedure, amount of dentine removed should be minimized, and the edges and corners which caused by fractured file removal should be shaped to smooth in order to reduce the stress concentration and prevent the root from fracture.

Endodontic Treatment of a Tooth with Traumatic Fracture of Root Middle Third.

Root fracture occurs in 0.5 to 7% of all dental injuries. Subsequent to this injury, the coronal segment is displaced, while the apical segment is rarely displaced. Emergency treatment involves repositioning of the coronal segment close to the radicular segment as much as possible to enhance the chance of pulp revascularization. If pulp necrosis occurs, the infective products cause an inflammatory response and radiolucency is seen at the fracture line. In the present case, the patient had two maxillary central incisors with horizontal middle third root fractures due to a traumatic accident four years earlier. The right central incisor showed an endodontic abscess due to pulp infection in the coronal segment. The coronal fragment was treated. In this case study all signs and symptoms resolved after treatment and three year follow-up showed a successful treatment outcome. The left central incisor had a vital pulp according to vitality tests, so "observation only" strategy was considered for this tooth.

Root canal preparation in mandibular premolars with TRUShape and Vortex Blue: A micro-computed tomography study.

A comparison of the preparation ability of two root canal instrumentation systems in oval-shaped canals using micro-computed tomography was undertaken. Thirty extracted, single-rooted, human mandibular premolars with radiographically similar canal morphology were selected, allocated to two groups (N=15) and prepared with TRUShape or Vortex Blue (VB). Each sample was subjected to three scans (20μm resolution): pre-preparation and after preparation to sizes #30 and #40. Three-dimensional data sets were evaluated for canal volume, surface area and surface treatment. Matched axial slices in apical, middle and coronal root thirds were evaluated for cross-sectional area, roundness and transportation. Preparation with both instruments increased canal volumes and surface areas similarly and significantly (P<0.001) with no significant difference between groups. TRUShape significantly enhanced surface treatment at both apical sizes (P<0.05). Transportation exceeded 100μm in only eight out of 90 cross sections. Both instruments performed similarly during preparation. TRUShape, however, significantly enhanced surface treatment.

In vitro assessment of interaction between lidocaine hydrochloride and sodium hypochlorite on root canal dentin before and after chemomechanical instrumentation procedures.

Introduction:To investigate the effect of resultant precipitate formed on interaction between 2% lidocaine hydrochloride with adrenaline (LA) and 2.5% sodium hypochlorite (NaOCl) on root canal dentin before and after chemomechanical preparation, using scanning electron microscopy (SEM).Methods:Sixty mandibular premolars were decoronated, and the root length was standardized. All specimens were randomly distributed into the following three groups: Group I (control): 2% LA mixed with sterile water without root canal instrumentation, Group II: 2% LA with 2.5% NaOCl and no instrumentation, and Group III: 2% LA with 2.5% NaOCl, followed by mechanical instrumentation with rotary files. Teeth samples were sectioned into three parts, split and SEM analysis of the root canal wall was done at cervical, middle, and apical root thirds.Results:SEM images revealed patent dentinal tubules with no precipitate occlusion in the control group, whereas there was occlusion of dentinal tubules with a precipitate in all the specimens in Group II and Group III at all the three root levels studied.Conclusions:The precipitate formed on the interaction between 2% LA solution and 2.5% NaOCl tends to occlude the dentinal tubules at the coronal, middle, and apical root thirds. The chemomechanical rotary instrumentation procedure did not effectively remove the precipitate from all the three levels of the root specimens studied. LA/sterile water group did not result in any precipitate formation on root canal dentin.