Coronal Thirds Research Articles

Guided Endodontic Access Cavity of Maxillary Obliterated Pulp Canal Lateral Incisor

Background: Managing severe calcified teeth in endodontics seems to be challenging for clinical, so static and dynamic guided endodontics ware developed to reduce the professional stress, increasing the patient\'s comfort, gives shorter clinical or procedural sessions with minimal invasive approach, and predictable canal location to avoid iatrogenic mishaps to be happened. Case Presentation: Preoperative investigations were conducted, tooth #12 had calcified chamber. Cone beam computed tomography (CBCT) was taken (Sirona GALILEOS Comfort CBCT scanner) showed that the coronal third of root canal is obliterated. For Guide planning, maxillary alginate impression was taken and scanned by digital scanner (smart optics - Vinyl High Resolution). Digital planning was done by 3Shape Implant Studio Software using sleeve size 3.5 mm (external diameter). Guided was printed by Digital Light Processing (DLP) 3d printing machine (NextDent 5100 3D printer). Enamel drilling by diamond round bur, guide was adapted to mouth and drill through until reach to 10 mm, periapical radiograph was taken to confirm the drilling depth. Conclusion: Guided treatment modality is not only used for anterior teeth or initial endodontic treatment, for posterior teeth and re-treatment endodontic cases as well. Finally, guided endodontic should be considered as mandatory treatment modality for pulp canal obliteration.

Investigation of mandibular second molar root and canal morphology in a Black South African population using cone-beam computed tomography and two classification systems.

To investigate the root and canal morphology of mandibular second molars, including anatomical variations, in a Black South African population using two classification systems. Cone-beam computed tomography images of 386 teeth were evaluated. The number of roots and canal configurations were categorized using the classifications of Vertucci (with modifications by Sert and Bayirli) and Ahmed et al. (including the modified Melton classification). Relationships between variables were assessed using Fisher's exact test (P < 0.05). Mandibular second molars were predominantly two-rooted (91.7%). The majority of teeth had three canals including Type IV mesial (41.2%) and Type I (75.1%) distal (Ahmed et al. configuration: 2MDM M2 D1). Three or more canals were present in almost one-fifth of mesial (n = 72/386, 18.6%) and a small number of distal (n = 21/386, 5.4%) roots. Males displayed additional canals more frequently in the distal root (P = 0.02). C-shaped anatomy was found in 5.7%. Among the C-shapes, the most common was Melton's Type III in the coronal (50%), middle (81%) and apical (72%) thirds. In this population, mandibular second molar teeth exhibited diverse morphology, which would have clinical significance for endodontic practitioners. The Ahmed et al. classification provided a better description than the Vertucci classification.

Efficacy of Three Irrigation Methods in Removing Calcium Hydroxide from Curved Root Canals: An In Vitro Micro-CT Study.

This in vitro study aimed to compare the efficacy of three different irrigation methods in removing calcium hydroxide from curved root canals and to estimate the amount of residual medicament using microcomputed tomography. Thirty extracted molars with curved mesial root canals, ranging from 25° to 30°, were prepared with ProTaper Next using X2 to full working length and were filled with calcium hydroxide. Teeth also were randomly divided into four groups: group 1 (n = 8)- Erbium: Yttrium-Aluminum-Garnet (Er:YAG) laser; group 2 (n = 8)-EndoActivator; group 3 (n = 8)-EndoVac; and a control group (n = 6)-negative control with no calcium hydroxide. Microcomputed tomography was used to evaluate the residual amount of filling material. Statistical analysis was performed using IBM SPSS Statistics 26, with a significance level of 0.05. Descriptive statistics, student t test, and Chi-square test were applied for data analysis. The greatest amount of residual calcium hydroxide was observed in the samples with EndoVac irrigation (0.515 mm3), followed by EndoActivator (0.381 mm3) and Er:YAG laser (0.121 mm3). However, no statistically significant difference was observed between the groups. The greatest residual amount was observed in the apical third (0.419 mm3), followed by the middle (0.050 mm3) and the coronal (0.015 mm3). No statistically significant differences were observed in the efficacy of the tested techniques for removing calcium hydroxide from curved root canals, whereas a significant difference was observed in the distribution of residual material depending on the technique used. The removal of the calcium hydroxide was more effective in the coronal and middle third of the canal. The greatest residual material was found in the apical portion of the root canal.

Evaluation of dislocation resistance of three different resin-based root canal sealers from radicular dentin -An ‘in vitro’ study.

&#x0D; Aim: The aim of this study is to evaluate the dislocation resistance of three different resin-based root canal sealers from radicular dentin -An ‘in vitro’ study.&#x0D; Methodology: Sixty extracted human maxillary canines were sectioned transversally below the cement-enamel junction to obtain 2-mm-thick dentin disks that were randomly divided into three groups (n = 20) for treatment with one of three different root-canal sealers (AH Plus [Dentsply DeTroy, Germany], Bioseal (Equinox Holland), EndoREZ [Ultra dent]). Standardized cavities were prepared to simulate root canals, cavities were filled with sealer material, and push-out bond-strength testing was performed using a universal testing machine.&#x0D; Result: In the present study amongst all the three sealers tested viz AH Plus, EndoREZ &amp; Bioseal. EndoREZ (Group III) goes most superior (14.97 ± 3.17 MPa), followed by AH Plus (Group II) (13.29 ± 2.27 MPa) &amp; the least bond strength was seen with Bioseal (Group I) (4.83 ± 1.62 MPa).&#x0D; There was a gradual decrease in bond strength from a coronal third of radicular dentin to the middle third followed by an apical third in all three groups.&#x0D; Conclusion: Amongst all the three-sealer tested EndoREZ® gave the maximum bond strength, followed by AH Plus® &amp; then Bioseal. Bioseal gave the least bond strength irrespective of the area in radicular dentin. There was a gradual decrease in bond strength from the coronal third of radicular dentin to the middle third followed by an apical third in all three groups.

Histological characteristics of dental pulp in teeth with periodontal problems and healthy teeth.

Chronic periodontitis is the most common type of periodontitis, which is associated with calculus and plaque accumulation. Several studies have indicated that uncured periodontitis can affect the dental pulp. However, this relationship is controversial. This study aimed to compare histopathological results obtained from the dental pulp in teeth with periodontal problems and healthy teeth. In this study, 23 teeth with periodontal problems and 23 healthy teeth were extracted. After cutting off 2 mm from the root apex, the teeth were sectioned into apical, middle, and coronal thirds. Then, the specimens were evaluated in both groups based on histopathological features. According to the evaluations, in the middle third, the amount of inflammation was only statistically significant in the group that consisted of teeth with periodontal problems (P=0.014). There was no significant difference in fibrosis and blood vessel diameter between the two groups. Necrosis in the middle (P=0.002) and coronal thirds (P=0.004) of teeth with periodontal problems was more than the healthy teeth. The lack of odontoblastic integrity in all the sections of teeth with periodontal problems was more than that in healthy teeth (P=0.0001). Inflammation of the periodontium in chronic periodontitis can lead to histological changes in the pulp, including an increase in inflammation, necrosis, and loss of odontoblastic integrity.

Comparison of five single-file systems in the preparation of severely curved root canals: an ex vivo study

BackgroundThe ex vivo study is to compare the root canal preparation outcomes achieved by five nickel–titanium single-file instrumentation systems (M3-L, Reciproc Blue, V-Taper 2H, WaveOne Gold, XP-endo Shaper) in severely curved molar root canals.MethodsA total of 60 root canals were selected from extracted human molar teeth with curvatures ranging from 25° to 50° and divided into five groups based on the instrumentation system employed (n = 12). Before and after root canal preparation, a Micro-CT scan was taken, and pre- and post-operative data were analyzed to evaluate the following parameters: volume increment of root canals (VI), untouched root canal areas (UTA), and canal transportation (CT). Apically extruded debris (AD) was collected during preparation. After that, all samples were separated into two parts and examined respectively by scanning electron microscope (SEM) to assess cleaning ability. Data were statistically analyzed with ANOVA (UTA, AD, VI) or Kruskal–Wallis test (CT, SEM-score), the level of significance was set at α = 0.05.ResultsThere were no significant differences between the five systems regarding the AD, VI, and UTA parameters (P > 0.05). In terms of CT, no significant difference was noted at the straight section of canal and apical levels, while XP-endo Shaper showed less canal transportation than M3-L at the level of curved vertex (P < 0.05), and the centering ability of V-Taper 2H was significantly better than WaveOne Gold at the initial point of bending (P < 0.05). Debris and smear layers were present on the canal walls of all specimens, the apical thirds of the canal presented higher SEM scores than the coronal thirds in all groups (P < 0.05). Reciproc Blue and XP-endo Shaper showed fewer smear scores than WaveOne Gold in the apical thirds (P < 0.01 and P < 0.05, respectively), and no statistical difference was found between other groups in the middle and coronal thirds.ConclusionThe five single-file systems evaluated performed equally in apically debris extrusion, dentin removal, and untouched root canal areas, while XP-endo Shaper and V-Taper 2H resulted in less canal transportation compared to M3-L and WaveOne Gold. Regarding cleaning ability, Reciproc Blue and XP-endo Shaper were associated with less smear layer than WaveOne Gold in the apical thirds.

The Influence of Brushing Motion on the Cutting Efficiency of Two Heat-Treated Endodontic Files: An In-Vitro Micro Computed Tomography Study

Background: To assess the cutting efficiency of two heat-treated endodontic files with a brushing motion in oval-shaped canals. Methods: A total of 10 intact lower molars with a single oval distal canal were selected and randomly divided into two groups according to the system used for shaping: 2Shape and Hyflex CM. The instrumentation was performed in two parts: a first shaping according to the manufacturer’s instructions and final shaping using 5 brushing motions on the distal, lingual, and buccal walls, avoiding the danger zones. Micro computed tomography (micro-CT) scans before and after the brushing motion were superimposed at all three levels: coronal, middle, and apical. Canal changes in buccolingual (ΔBL) and mesiodistal (ΔMD) dimensions were measured. Data were statistically analyzed by repeated-measures analyses of variance and the student t-test (p &lt; 0.05). Results: For ΔMD, no significant difference emerged between the 2Shape and Hyflex CM in the apical and coronal thirds. However, the cutting efficiency was significantly greater with the 2Shape in the middle third (p &lt; 0.05). Regarding ΔBL, no statistically significant difference was detected between 2Shape and Hyflex CM comparing the anatomical thirds, while 2Shape had a significant higher cutting efficiency considering the total BL diameter (p &lt; 0.05). Conclusions: Under the limits of a vitro study, the shaping procedure with 2Shape and brushing motion was more efficient than the Hyflex CM in the midroot levels in terms of ΔMD, and in total canal space for ΔBL. Both files ensured an effective mechanical preparation.

Comparison of Color Accuracy between Natural Dentin Substrate and Three Dentin Porcelain Brands of Glass-Matrix Ceramic System (Digital Image Analysis)

Purpose: The purpose of this laboratory study was to differentiate the color of natural dentin (ND) and dentin porcelain (DP) by using three brands of Glass-Matrix Ceramic System (GMCS) by parametric CIE L*, a*, b* system. Materials and methods: An extracted human upper central incisor was prepared as a control group. Uniformly thick dentin specimen was taken from the middle coronal third of the labial half longitudinally. Twelve disks of GMCS dentin porcelain were fabricated according to manufactures' instructions by using conventional powder/slurry technique, 4 disks for each group; Feldspathic ceramic VITA VMK 95 (VMK), Leucite-based ceramic VITA VM9 (VM9), and Fluorapatite-based ceramic IPS e.max Ceram IVOCLAR (IEC). ND and DP specimens' thickness were (8×1 mm, shade A3) and (n=4). A digital camera was used to take samples' photos while the color readings were obtained by graphic software. The specimens' colors were measured, and the data were statistically evaluated using Levene's test, One-way ANOVA, and Post Hoc Multiple Comparisons. Results: Parametric CIE L*, a*, b*, and ΔE values of all ceramic disks compared to ND were significantly different even within ceramic brands (P&lt;.05), ΔE were ND &gt; IEC &gt; VMK &gt; VM9. Conclusions: To reproduce ND color by DP needs proper color shade guide selection due to color differences from one brand to another even in the same shade guide tab. Clinical Significance: There is a lack of information on how identical natural dentin color to dentin porcelain is at the same shade guide.

Evaluation of the Efficacy of Different Irrigation Systems on the Removal of Root Canal Smear Layer: A Scanning Electron Microscopic Study

Irrigation represents a crucial step in endodontics for bacteria disinfection and smear layer removal. Several irrigation strategies have been proposed, although their effects are controversial. This study aims to assess the comparison of four different irrigation systems on the smear layer removal utilizing scanning electron microscopy (SEM). Forty sound monoradicular teeth were collected and casually allocated into four groups (n = 10): Group A, conventional irrigation; Group B, IrriFlex irrigation; Group C, ultrasonic irrigation system; Group D, apical negative pressure irrigation. After chemo-mechanical preparation and longitudinal root separation, the three root thirds were analyzed by SEM. Micrographs were carried out at ×2000 to analyze the smear layer residual in each third of the root canal. Statistically significant differences were found between Group A and Group D (p &lt; 0.05). Groups B and C showed satisfactory results in the coronal and middle thirds, while Group D was the only system that achieved satisfactory results in the apical third. However, the complete smear layer removal in the root canal was never achieved with any of the four systems tested. In conclusion, among the four tested irrigation systems, the greatest efficacy on smear layer removal was reached by Group D.

Effect of Different Root Canal Drying Protocols on the Bond Strength of Two Bioceramic Sealers.

This study evaluated in vitro the effect of two different drying protocols on the dentin bond strength of two different bioceramic sealers (Sealer Plus BC [SP] and Bio C Sealer [BCS]). Bond strength and failure mode were evaluated according to the sealer, drying protocol, and root canal third. Sixty extracted human mandibular single-rooted premolars were selected after anatomical standardization. The crowns were sectioned and root canals were prepared. Roots were randomly divided into four groups (n = 15 each). Each group was assigned a combination of one of the evaluated sealers (SP or BCS) and one of the drying protocols: canals dried with paper points (PP) or irrigation with saline followed by aspiration with silicon cannulas (IA). Obturations were performed using a single-cone technique. The teeth were temporized and stored for 7 days (100% humidity, 37°C). Roots were cut to obtain 2 mm thick discs for each third (coronal, middle, and apical). Push-out tests were performed on a universal testing machine, and the bond strength (MPa) of each specimen was calculated by dividing the load (N) by the interface area. Failure type was assessed under ×4 magnification. Data were statistically analyzed with a significance set at 5%. An analysis of variance test followed by the Games-Howell post-hoc test was used to compare the mean values between the groups and the interaction of the variables. The predominant failure type was cohesive, followed by mixed failure and adhesive in all groups. The apical third presented the highest bond strength (p < 0.05) regardless of the group, followed by the middle and coronal thirds. Overall, the SP PP group had the highest mean bond strength (p < 0.01), but the SP sealer was negatively affected by the IA drying protocol in the coronal and middle thirds. The BCS presented similar results within the third stage, regardless of the drying protocol. Sealer Plus BC had a higher bond strength than Bio C Sealer, but it was negatively affected by the irrigation-aspiration protocol in the coronal and middle thirds. For the apical third, there was no difference between the groups; thus, a similar bond strength was observed regardless of the drying protocol or sealer.

Evaluation of Dentinal Microcracks following Diode Laser- and Ultrasonic-Activated Removal of Bioceramic Material during Root Canal Retreatment.

This study is aimed at evaluating the use of microcomputed tomography (micro-CT) analysis and the dentinal microcrack formation following retreatment of bioceramic sealer employing adjunct laser-activated irrigation and ultrasonic-activated irrigation. Thirty sound human single-canal teeth (n = 30) obturated using the single-cone technique with bioceramic sealer were retreated using nickel-titanium (NiTi) rotary files. The sample was randomly divided into three equal groups: group 1, the control group, was not subjected to further treatment; group 2 underwent ultrasonic activation of irrigants; group 3 underwent active irrigation with a diode laser (980 nm wavelength). Using micro-CT, the teeth were scanned before and after retreatment protocols. Two calibrated experienced observers viewed the cross-sectional images and calculated the number of dentinal defects. The presence of any crack or craze line on the external root surface or internal canal wall was counted. Data were analyzed using Friedman's two-way analysis of variance and Fisher's exact test. Statistical significance was set at p < 0.05. A significant increase occurred in the number of cracks post retreatment protocols, specifically in the coronal and middle canal thirds, compared to pre- and postinstrumentation (p = 0.0001). However, ultrasonic- or laser-activated irrigation did not result in a significant increase in the number of cracks (p = 0.345). NiTi rotary root canal retreatment was associated with a significant increase in dentinal microcracks. However, employing ultrasonic- or laser-activated irrigation as adjunct retreatment techniques did not reveal a significant increase in dentinal microcracks within the roots.

Reciprocating System for Secondary Root Canal Treatment of Oval Canals: CBCT, X-rays for Remnant Detection and Their Identification with ESEM and EDX

Aim of the study: to evaluate root filling remnants after secondary root canal treatments (SRCTs) of oval-shaped canals with X-rays and cone beam computed tomography (CBCT). The SRCTs were performed using reciprocating NiTi instruments. Methods: Single-rooted teeth (N = 64) were randomly treated with Reciproc Blue (RB) and filled with AH Plus/single cone (SC group) or AH Plus/Guttafusion (GF group). After seven days of storage in HBSS (Hanks balanced salt solution), Gates Glidden burs #2/3 and RB #25 and #40 were used for the SRCTs. The time to complete the procedure was measured. X-rays and CBCT were used to calculate, respectively, the area and the volume occupied by the remnants in the coronal, middle, and apical thirds of each canal. Environmental scanning electron microscopy (ESEM) and energy dispersive X-ray spectroscopy (EDX) were used for qualitative evaluation and morphology composition of the remnants in sectioned roots. A statistical analysis was performed using Sigma Plot (version 13, IBM, Armonk, NY, USA). The study was designed according to PRILE guidelines. Results: After the SRCTs, the middle thirds of the root canals showed the presence of remnants in both groups, as demonstrated by X-rays and CBCT. The GF group showed a statistically significant higher volume of remnants than the SC Group only in the middle third. The ESEM supported by the EDX revealed the remnant composition by the detection of trace elements of sealer and gutta-percha in all root canals. Conclusion: The study demonstrated that the middle third of root canals is a critical region where remnants were packed and spread in the buccal-lingual sides of canals. ESEM-EDX detected a fine layer of filling remnants in all root thirds, suggesting a larger canal contamination than the X-rays and CBCT examinations revealed.

The Bond Strength of Root Canal Filling after Calcium Hydroxide Removal with a Simple Apical Negative Pressure Kit in Oval-Shaped Root Canal.

The aim of this study was to evaluate the effect of a simple irrigating device, which produced from the apical negative pressure concept, as a final irrigating method after calcium hydroxide (CH) medication on the bond strength of epoxy resin-based sealer in the oval-shaped root canal. Forty-eight single-rooted premolars with oval-shaped canals were included in the study. The crown was decoronized and canal instrumented with Mtwo (VDW GmbH, Munich, Germany) up to size 40/04. The specimens were assigned to four groups according to the irrigation protocol after 1 week of CH medication: control group (no medication) and three experimental groups conventional needle irrigation (CNI), passive ultrasonic irrigation (PUI), and simple apical negative pressure kit (sANP). The teeth were obturated with a warm vertical technique using epoxy resin-based sealers. After 1 week, the roots were transversally sectioned at coronal, middle, and apical thirds. A push-out test was performed by a universal testing machine, and statistical analysis was performed using One-Way ANOVA with Duncan's post hoc test. The bond strength in the control group was significantly higher than the CNI group in all root canal thirds (P < 0.05). At coronal third, sANP showed lower bond strength than PUI group (P < 0.05). However, the bond strength of sANP group was comparable to the control group (P > 0.05) which was significantly higher than the PUI group at apical third (P < 0.05). A sANP enhanced the bond strength of epoxy resin-based sealer in the apical third of CH-medicated root canal in the oval-shaped canal.

Evaluation of the Bond Strength of Epoxy Resin-based Sealer Following Different Calcium Hydroxide Paste Removal Methods in Oval-shaped Root Canal

The study aimed to investigate the bond strength of epoxy resin-based sealer following five different calcium hydroxide paste removal methods in oval-shaped root canals. Sixty single-rooted human mandibular premolars having an oval-shaped root canal as evidenced by radiographs were decoronated and instrumented to size 40/0.04, medicated with calcium hydroxide paste for 7 days, before being randomly assigned to the conventional needle irrigation (CNI), manual dynamic agitation (MDA), sonic irrigation (SI), passive ultrasonic irrigation (PUI), and XP-endo Finisher (XP) groups to be irrigated using different irrigation systems. All specimens were then obturated using an epoxy resin-based root canal sealer and warm vertical compaction obturation technique. After 7 days, each specimen was sectioned into 1 mm root slices at the coronal, middle, and apical third of the root canal and tested for the push-out bond strength using a universal testing machine. The XP group was the only group that had comparable bond strength to the control group at every level of the root canal following removal of calcium hydroxide medicament (p >0.05). The control group had higher bond strength than the CNI group at every level of the root canal (p < 0.05). Calcium hydroxide interfered with the bonding of epoxy resin-based sealer to root canal walls. Irrigation with the XP increased the bonding sealer at every level of the root canal. The XP was efficacious as a final rinse agitation technique to promote the bonding of the epoxy resin-based sealer at every level of the root canal following calcium hydroxide medication.

Effects of chitosan-containing silver nanoparticles or chlorhexidine as the final irrigant on the bond strength of resin-based root canal sealers.

Background. This study evaluated the combined effects of silver nanoparticles (AgNPs) and chitosan on the dentin bond strength of resin-based root canal sealers using the push-out test and scanning electron microscopy (SEM). Methods. This in vitro study was conducted on 72 extracted mandibular premolar teeth. All the teeth were decoronated perpendicular to the long axis to leave a 13-mm root length. The root canals were prepared, and the samples were randomly divided into seven experimental groups and one control group based on final irrigation solutions. All the final irrigation procedures were performed for one minute. The root canals were dried using paper points and filled with a resin-based sealer and gutta-percha points using a lateral condensation technique. Sections measuring 2 mm in thickness were taken from the apical, middle, and coronal thirds of each root using a cutting machine. The push-out test was performed using a universal testing machine. Results. The solution of AgNPs combined with 0.4% chitosan showed higher bond strength in the coronal region than a combination with 0.2% chitosan. Samples treated with 0.4% chitosan solution exhibited a higher bond strength than the 0.2% chitosan group. There were no significant differences between chlorhexidine (CHX) solution alone and in combination with 0.2% or 0.4% chitosan solution. Conclusion. The combination of chitosan and AgNPs was as effective as CHX in improving the bond strength of resin-based sealers.

Update on citric acid use in endodontic treatment: a systematic review.

This systematic review aims to analyse the available evidence concerning the use of citric acid (CA) in endodontics treatment and to assess its results in terms of different considerations: effect on smear layer removal, influence on sealer bond strength, activation effect by means of sonic or ultrasonic devices, effects on dentine surface, antibacterial activity, and effectiveness boost for regenerative procedures, releasing growth factors from dentin. To evaluate the results of CA as a final irrigant and compare them to other chelating agents. This review followed the PRISMA checklist. An electronic search was conducted in MEDLINE (OVID), Scopus (Elsevier) and the Web of Science (Thomson Reuters) databases. Risk of bias of included studies was evaluated using the modified CONSORT checklist and the PRIRATE checklist 2020 guidelines. 39 studies fulfilled the eligibility criteria to be included in this review: 27 in vitro studies using extracted human teeth, 10 in vitro studies using human dentin disks, and 2 RCT. Citric acid has proven to be effective in smear layer removal, showing better results in coronal and middle root thirds, improving its effect when combined with manual dynamic activation. There is no agreement regarding citric acid effect on sealer adhesion and adaptation to root canal walls due to heterogeneity within studies. Citric acid irrigation can decrease dentine microhardness and cause decalcification and erosion, especially when used before NaOCl. Citric acid has proven to be beneficial in regenerative endodontic procedures due to higher TGF-β1 release.Trial registration: Prospero database CRD42021267055.

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.

Influence of root canal moisture conditions on the bond strength of endodontic sealers to dentin

Objective: To investigate the influence of intraradicular moisture conditions on the bond strength of 3 different endodontic cements in the coronal, middle, and apical thirds of the root canal. Materials and Methods: 90 single-rooted teeth were instrumented with a reciprocal R#50 file and randomly divided into 3 experimental groups: Dry group: dry canals with absorbent paper tips; Moist group: suction syringe and capillary tip coupled to a vacuum pump; Wet group: aspiration with endodontic suction. The groups were divided according to the endodontic sealer used: AH plus (Denstply), Hiflow (Brasseler) and Bio-c Sealer (Angelus). Obturation was performed using Tagger's hybrid technique with a single cone. The teeth were subjected to the "push-out" test to evaluate the bond strength of the cements. Results: Data were analyzed using the Kolgomorov-Smirnoff normal distribution test and the Mann Whitney U test to compare means within and between groups. The standard error established was 5% at a significance level of 95%. AH plus showed better results regardless of canal moisture conditions. Hiflow showed better bond strength in the dry group compared to the moist group (p=0.023) in the cervical area. Bio-C Sealer showed no statistically significant differences (p &gt; 0.05). Conclusion: Moisture conditions affected the bond strength values of endodontic cements. The prevalence of failure moduli was mixed in all root thirds, regardless of the cement used.

Micro-Computed Tomography Evaluation of Minimally Invasive Shaping Systems in Mandibular First Molars.

The aim of this study was to compare the shaping ability of a modified ProTaper Next technique (PTNm) with that of TruNatomy (TN) in lower molars mesial curved canals using micro-computed tomography (Micro-CT). Sixty mesial canals of first mandibular molars were randomly assigned between two groups (n = 30). After canal scouting with K-File #10, glide path and shaping were carried out with TN or PTNm systems. The PTNm sequence consists of ProGlider, followed by ProTaper Next X1 and apical finishing with NiTiFlex #25 up to working length (WL) to ensure adequate apical cleaning. Samples were scanned using micro-CT and pre- and post-shaping volumes were matched to analyse geometric parameters: the volume of removed dentin; the difference of canal surface; centroid shift, minimum and maximum root canal diameters; cross-sectional areas; the ratio of diameter ratios (RDR) and the ratio of cross-sectional areas (RA). Measurements were assessed 2 mm from the apex and in relation to the middle and coronal root canal thirds. Data were analysed using ANOVA (p < 0.05). No statistically significant differences were found between the groups for any parameter at each level of analysis, except for RA at the coronal level (p = 0.037). The PTNm system showed the tendency to enlarge more in the coronal portion with a lower centroid shift at apical level compared with TN sequence (p > 0.05). Both PTNm and TN sequences demonstrated similar maintenance of original anatomy during the shaping of lower molar mesial curved canals.

Development of a predictive model for identifying previously undetected vertical root fractures.

This study aimed to develop a predictive model to screen for undetected vertical root fractures (VRFs) in root canal treated teeth. We included 95 root canal treated teeth with suspected VRFs; 77 for training and 18 for validation. Following clinical and cone-beam CT parameters were recorded: sex, tooth type, coronal restoration, time interval from completion of endodontic treatment to definitive diagnosis (TI), type of bone loss (BL), apical extent of root filling (AR) and the ratio of root filling diameter to the actual diameter in the coronal (1/3TA) and middle (2/3TA) root thirds. A predictive model p=1/(1-e-x ) was generated, where x=-7.433 + 1.977BL + 1.479 (2/3TA) + 1.102 AR; the sensitivity and specificity were 0.852 and 0.875 for training and 0.917 and 0.833 for validation. VRF teeth were more likely to have vertical bone loss and overfilled root canals. This model had a high diagnostic efficacy for VRFs.