Root Canal Surface Research Articles

Exploring access cavity through non-carious cervical lesions: Impacts on instrumentation, obturation, and fracture resistance in mandibular incisors.

To compare the effects of Cervical Access Cavity (CervAC) and Traditional Access Cavity (TradAC) on root canal preparation, root canal filling, and fracture resistance in mandibular incisors. Twenty recently extracted and intact mandibular incisors were initially scanned using a micro-CT device. The specimens were anatomically matched to create two groups (n = 10). A wedge-shaped non-carious cervical lesion (NCCL) was created on the buccal aspect of all teeth using a double-faced segmented diamond disc. In group 1, a TradAC was prepared, whilst in group 2, access was created through the simulated NCCL using a round diamond bur 1012. After root canal preparation with Rotate instruments sizes 15/0.04, 20/0.04, and 25/0.04, the teeth were scanned again and evaluated for root canal volume and surface area, static voxels, volume of removed dental tissue, and dentine thickness. After that, the root canals were filled using the single-cone technique, teeth were restored with composite resin, and subsequently rescanned to calculate the volume of filling materials and voids. Then, the restored teeth were subjected to fracture resistance tests using a universal testing machine. Statistical comparisons between groups were performed with the Mann-Whitney test or the Student's t-test, with a statistical significance level of 5%. Statistical comparisons indicated no significant differences between groups in terms of root canal volume, surface area, static voxels, removed root dentine, root canal filling volume, percentage of voids, or fracture resistance load (p > .05). Conversely, teeth prepared with TradAC showed a significantly higher percentage of dental tissue removed from the crown (p = .001) and a greater volume of filling material remnants in the pulp chamber (p < .001) compared to the CervAC group. A significantly lower percentage reduction in dentine thickness was observed only on the mesial aspect of root at Level 1 in TradAC group (p = .008). CervAC can be considered a viable alternative approach in the presence of NCCL in mandibular incisors.

The Efficiency of Erbium Lasers in the Removal of Root Canal System and Surface Biofilms: A Systematic Review and Meta-Analysis.

Background: Studies have shown positive effects of erbium lasers in removal of biofilms. A review article was required with quantitative data for confirmation of their effects, but there is still no a comprehensive study reviewing their effects based on the root canal and implant surface. This systematic review and meta-analysis was conducted to evaluate the efficiency of erbium lasers in removal of the root canal system and surface biofilms. Methods: Studies were searched with keywords in databases of PubMed, Scopus, Europe PMC, Cochrane Central, Embase, and Web of Science and screened by referees. Data were included based on mean ± standard deviation and size of control and laser groups. Effect sizes were assessed as standardized mean differences and calculated for each study and for the root and dental surface. Laser characteristics and bacteria were considered as moderators. Results: Nineteen articles in the current study comprised 565 samples (283 control samples and 282 laser samples). The analyses showed the significant effects of erbium lasers on bacterial biofilms on the implant surface [-0.496, 95% confidence interval, CI (-0.720 to -0.273); I2 = 26.94; p = 0.029; Q = 13.28] and root canal [-0.551, 95% CI (-0.656 to -0.445); I2 = 23.89; p = 0.031; Q = 10.46]. Results showed that highest efficiency lasers were obtained at higher wavelengths of 2940 nm, 75-100 mJ energy, and 100-150 μsec and <50-Hz pulses. Conclusions: Erbium lasers can be used to remove biofilms on dental implant surfaces and root canal systems and are safe options for untouchable sites in the root canal.

Micro-computed tomographic evaluation of the shaping ability of three nickel-titanium rotary systems in the middle mesial canal of mandibular first molars: an ex vivo study based on 3D printed tooth replicas

BackgroundThe preparation of the middle mesial (MM) canal of mandibular molars represents a challenge because it is often curved, narrow, and close to the root concave. The purpose of this study was to evaluate the ex vivo shaping ability of 3 nickel-titanium (NiTi) rotary systems in the MM canal using 3D printed resin tooth replicas.MethodsA permanent mandibular first molar with a MM canal was acquired from a pool of extracted teeth and reproduced by a 3D printer. The resin tooth replicas (n = 18) were equally assigned to 3 groups for the evaluation of the shaping abilities of 3 NiTi rotary systems (OneShape [OS], Twisted Files [TF], and ProTaper Gold [PTG]) according to the manufacturer’s recommendations. The tooth replicas were scanned by micro-computed tomography (micro-CT) twice before and after instrumentation of the mesiobuccal (MB), mesiolingual (ML), and MM root canals. After 3D reconstruction, the canal straightening, change of root canal volume and surface area, the mesial and distal canal wall thickness and canal transportation at the levels of 1, 2, and 3 mm below furcation were assessed. One-way variance analysis and Turkey’s post hoc test were used for comparisons of the means among different groups, and paired-t test was used to compare the mesial and distal sides of the mesial roots.ResultsAs compared with OS and TF, the use of PTG in preparation of MM canals resulted in significantly more straightening of canal curvature (p < 0.05), greater post-instrumentation canal volume and surface area, and thinner mesial and distal remaining canal wall thickness at 1, 2 and 3 mm below furcation (all p < 0.05). Regarding the root canal transportation in the mesiodistal direction, there was no significant difference among the 3 instruments (all p > 0.05) after the preparation of the MB and ML canals. However, in the MM canal, more pronounced transportation was detected in the PTG group at 2 mm below furcation, and in the TF group at 3 mm below furcation as compared with the other 2 systems (both p < 0.05).Conclusions3D printed tooth replicas have the advantages of consistency and can be an ideal model to evaluate the shaping ability of different instruments in the MM canal. OS and TF files performed similarly and both are appropriate for shaping the MM canal, while PTG may cause excessive and uneven resin removal, especially near the furcation, and may lead to root fragility and procedural errors.

Smear Layer Removal Efficacy of EDTA and Citric Acid in Endodontics

Introduction: Smear layer is formed by organic and inorganic components generated during endodontic instrumentation. Smear layer has many deleterious effects on the success of root canal treatment. So removal of smear layer is advocated. Sodium Hypochlorite (NaOCl) and a chelating agent like Ethylene Diamine Tetra Acetic Acid (EDTA) or Citric Acid is commonly used alternatively to remove smear layer. But the alternate use increase dentine erosion in root canal surface. This in vitro study attempts to compare the smear layer removal efficacy of 15% EDTA &amp; 10% Citric Acid as a final rinsing solution. Materials and Methods: Forty extracted, single rooted and single canal human anterior tooth were used. Endodontic preparation of the root canal was done after grouping and access cavity preparation. Final irrigation was given with 15% EDTA &amp; 10% Citric Acid to the test groups and distilled water control groups and kept for one minute. Photomicrograph of the root canal surface at 3000X magnification at coronal, middle and apical regions were taken with the help of SEM and scoring for smear layer removal was done. Data was analyzed using SPSS version 16 and were compared with the control samples and subjected to statistical analysis by one way ANOVA and Bonferroni multiple comparison tests at 5% level of significance. Result: The test solutions removed smear layer but none could be removed completely from all of the three root canal regions. 10% Citric Acid removed smear layer better from the coronal and middle region but in apical region 15% EDTA produced a better result. The difference of smear layer removal efficacy of 15% EDTA &amp; 10% Citric Acid with the Control solution was found statistically significant (p&lt;0.001) but in between 15% EDTA &amp; 10% Citric Acid it was not significant in all three root canal regions. Conclusion: Regarding the smear layer removal efficacy of 10% Citric Acid was found better as a final rinse solution. Update Dent. Coll. j: 2023; 13(2):9-14

Scanning Electron Microscopy Analysis of Smear Layer Removal Ability of Conventional Endodontic Irrigation Regimen, MTAD, and QMix™ Versus a Mixture of Azadirachta indica and Citrus limon: An In Vitro Study.

Smear layer removal from root canals aid in the penetration of both irrigants and endodontic sealer into the dentinal tubules, thereby improving the efficacy of endodontic treatment. The aim of this in vitro study was to compare the smear layer removal ability of a conventional endodontic irrigation regimen, MTAD (mixture of tetracycline, acid, and detergent), and QMix™ (Dentsply Sirona, Charlotte, North Carolina, United States) with that of a mixture of herbal irrigants, namely, aqueous extracts of Azadirachta indica (neem) and Citrus limon (lemon), evaluated using scanning electron microscopy (SEM). We selected 40 extracted human premolar teeth for the study, which we randomly divided into five groups (eight samples each) according to irrigation solution: (i) Group A (normal saline); (ii) Group B (conventional endodontic regimen, 3% sodium hypochlorite (NaOCl) + 17% ethylenediamine tetraacetic acid (EDTA) + 2% chlorhexidine (CHX)); (iii) Group C (MTAD); (iv) Group D (QMix 2-in-1); and (v) Group E (aqueous extracts of Azadirachta indica and Citrus limon). After we prepared the canals with ProTaper Universal nickel-titanium (Ni-Ti) rotary files (Dentsply Sirona) and the respective irrigants, we split the teeth longitudinally to evaluate the amount of remnant smear layer in the coronal, middle, and apical thirds using SEM photomicrographs. We performed statistical analyses of the data using the Kruskal-Wallis and Mann-Whitney U tests, where the level of significance was set at 0.05. The SEM analysis of the coronal third showed mean valuesof 3.83 in Group A, 3.67in Group B, 2.79in Group C, 3.63in Group D, and 4.00in Group E. The SEM analysis of the middle third showed mean values of 4.00 in Group A, 3.88in Group B, 3.75 in Group C, 3.50in Group D,and 3.50 in Group E.The SEM analysis of the apical third showed mean values of 3.92 in Group A, 3.63in Group B, 3.71in Group C, 3.88 in Group D, and 3.17 in Group E.Therefore, we found that there were significant statistical differences between the groups when an overall comparison was done for the coronal, middle, and apical third, with a p-value of 0.001. On multiple comparisons across the different tooth-section thirds. Groups A and B showed statistically significant differences in the apical third (p-value=0.017). Groups A and C showed statistically significant differences in the coronal third and middle third (p-values=0.001 and 0.010, respectively). Groups A and D showed statistically significant differences in the middle third (p-value=0.001). Groups A and E showed statistically significant differences in all thirds (p-values=0.039, 0.001, and 0.001, respectively) Conclusion: The conventional needle irrigation with MTAD showed the highest level of smear layer removal ability on the root canal surface, followed by QMix 2-in-1, the Azadirachta indica leaf and Citrus limon extract mixture, and the conventional endodontic regimen. Normal saline showed the lowest smear layer removal effect.

Morphological Analyses of Effects of Endodontic Irrigant Solutions Using a Root Canal Model and an Immersion Model.

This study aimed to compare an experimental model simulating clinical root canal irrigation (root canal model) with a conventional experimental model immersing dentin sample to irrigants (immersion model) to evaluate removal of the smear layer and decalcification of the root canal dentin using sodium hypochlorite (NaOCl) and two different concentrations of ethylenediaminetetraacetic acid (EDTA) solution. Forty-five single-rooted extracted human teeth were prepared using a Ni-Ti rotary file. EDTA, NaOCl, and citric acid were used in the root canal models and the immersion models. After the irrigation protocol, root canal surfaces were observed under scanning electron microscopy. Residual smear and decalcification of the root canal dentin were evaluated objectively by measuring the percentage of the area occupied by visible dentin tubules, the number of visible dentin tubules, and the mean area of a visible single dentin tubule. Root canal and immersion models with the same irrigation protocol showed significantly different results for smear residues and decalcification of root canal dentin. In the root canal model, neither different EDTA concentrations nor the order of EDTA and NaOCl applications significantly impacted smear residues or decalcification of root canal dentin. Furthermore, no erosion of the root canal dentin surface was observed in any experimental groups in the root canal model using EDTA and NaOCl compared to intact dentin. Experimental design affected results for residual smear layer and decalcification of root canal dentin. The order of EDTA and NaOCl use and the concentration of EDTA did not affect results. EDTA and NaOCl irrigation did not cause erosion in the root canal model in this study.

Efficiency of Different Agitation Methods for Removal of Calcium Hydroxide Intracanal Medicament Mixed with Two Different Vehicles from Canals of Mandibular Premolars: A Volumetric Analysis using Cone-beam Computed Tomography

Introduction: The purpose of this research was to use cone-beam computed tomography (CBCT) to examine the efficacy of hand and rotary files, manual dynamic agitation, and inactive ultrasonic actions in removing Ca(OH)2 from root canal surface when used in conjunction with two distinct vehicles. Materials and Methods: Using the ProTaper Gold file system, the root canals of 100 mandibular premolars were cleaned and shaped up to file F2, and then filled with either Ca(OH)2 + saline or Ca(OH)2+ camporated monochloro-phenols. After 7 days of incubation, CBCT was used to do a prevolume analysis. Several forms of agitation were used to successfully remove calcium hydroxide (K- and H-file, ProTaper Gold rotary file, passive ultrasonic irrigation (PUI), and manual dynamic agitation). CBCT was used to reevaluate the volumes after the fact, &amp; the percentage of change was determined the Post Hoc Tukey test, One-way ANOVA, &amp; the Dunn test were utilized to analyse the data statistically. Results: Saline-based Ca (OH) 2 was little simple to be separate than camporated monochloro-phenols (CMCP)- based group. When the agitation systems were compared, H-file in both the groups removed more calcium hydroxide from root canals than other systems (P &lt; 0.01). Conclusion: The H-file system and PUI were more effective than the K-file, rotary, and manual dynamic agitation methods in eliminating calcium hydroxide from root canals. However, the saline-based calcium hydroxide was easier to be removed than camphoro monochlorophosphate.

The combined treatment of fiber post and root canal by the Er:YAG laser enhances the bond strength of composite reconstruction.

Fiber post bonding failure remains an issue during crown restoration procedures. This experiment examines the bonding effect of combined Er:YAG laser treatment on both root canal and fiber post. Sixty extracted mandibular first premolars were randomly selected and divided into 6 groups (n = 10 per group): G1 (control group): root canal with 2.5% NaClO treatment, no treatment of fiber post; G2: root canal with 2.5% NaClO treatment and fiber post with airborne-particle abrasion; G3: root canal with Er:YAG laser treatment and fiber post with airborne-particle abrasion; G4: root canal with Er:YAG laser treatment, no treatment of fiber post; G5: root canal with 2.5% NaClO treatment, fiber post with Er:YAG laser irradiation; G6: combined Er:YAG laser irradiation of both root canal and fiber post. An Er:YAG laser with a wavelength of 2940nm was used to treat the fiber post (4.5 W, 450mJ, 10Hz for 60s at 100-μs pulse duration with 100% water cooling) and the root canal (1.5 W, 150mJ, 10Hz for 60s at 100-μs pulse duration with 100% water cooling). When the root canal was treated with the laser, the fiber tip was inserted into the root canal to make a spiral reciprocating motion. Bond strength was analyzed by a micro push-out test. Data were analyzed using both the Tukey test and two-way ANOVA (α = 0.05). Failure modes were observed and counted through a stereo microscope. The root canal and fiber post surface analysis was performed using SEM. The bond strength of G3 and G6 were significantly enhanced compared to those of the other groups (p < 0.05). The SEM analysis showed that the smear layers of groups with root canals subjected to Er:YAG laser irradiation were significantly reduced compared to those of the control group (G1). In groups with fiber posts treated with Er:YAG laser irradiation, the surfaces of the fiber posts exhibited greater surface roughness and a certain degree of epoxy matrix removal. Through the combined Er:YAG laser irradiation of both root canal and fiber post, the bond strength between them was significantly enhanced, which was superior to the individual treatment of either fiber posts or root canal.

Shaping ability of BlueShaper, TruNatomy, DC Taper and HyFlex EDM in long oval canals: An ex vivo study.

This study evaluated and compared the shaping ability of four rotary instrument systems in long-oval root canals using microcomputed tomographic (micro-CT) evaluation. Currently, there is no data available on the canal shaping abilities of BlueShaper and DC Taper instruments. Sixty-four single-rooted mandibular premolars were matched based on similar root canal morphologic features as determined by (micro-CT) and randomly assigned to 1 of 4 experimental groups (n = 16) according to the instrument system used: BlueShaper, TruNatomy, DC Taper and HyFlex EDM One File. Changes in the root canal surface and volume, remaining dentine thickness, and number of prepared areas were assessed. No significant differences were found amongst the four instrument systems for the parameters evaluated (p > .05). There was a significant reduction in the number of unprepared areas and the remaining dentine thickness after each increase in size of the instruments tested (p < .05). The four instrument systems perform similarly in long oval root canals. Although none could prepare all canal walls, larger preparations incorporated significantly more surfaces in the final shape.

Morphological and Physiological Adaptations of Microbes in Root Canal Biofilms - A Literature Review

Microbial flora in the oral cavity gain entry into root canals after pulpal exposure, either due to trauma or dental caries. Once inside the root canal, bacteria of different species organize into a network and communicate with each other to withstand the chemical and physical disturbances during the treatment. They cause extraradicular infections that do not respond to conventional endodontic therapies. Bacteria present on the surface of root canals organize into a framework consisting of the matrix, bacteria, and water. The matrix consists of extracellular polysaccharide, which varies with the species that secrete them. It also contains proteins, fatty acids, and extracellular DNA, which help in the growth of the matrix, survival, and pathogenesis of organisms. Microorganisms entering the root canals should survive the nitric oxide rich, oxygen stressed, and nutrient-deprived environment. They should also resist the chemical and mechanical disturbances created during endodontic treatment to enable their persistence in the root canals. This review aims to discuss biofilm formation and the mechanisms by which it helps in bacterial survival in root canals.

Shaping ability of WaveOne Gold and OneReci by using two apical sizes: a micro-computed tomographic assessment.

OneReci (MicroMega, Besançon, France) is a recently introduced single-file reciprocating system with scarce information revealed on its shaping ability. This study aimed to compare the shaping abilities of OneReci and a well-documented single-file reciprocating system WaveOne Gold (WOG; Dentsply Maillefer, Ballaigues, Switzerland) and evaluate the effect of increased apical enlargement on the preparation quality, using micro-computed tomography (micro-CT). After an initial micro-CT scanning, twenty mesial root canals of mandibular molars were anatomically matched. The canals were assigned to two experimental groups (n=10), using OneReci or WOG in different canals of the same root. The glide paths were created, and root canals were prepared twice, using size 25 and 35 instruments of the systems, respectively. The specimens were scanned with micro-CT after each preparation. The increase in canal volume, amount of dentin removal, unprepared root canal surface, canal transportation, centering ratio and preparation times were assessed. The data were analysed with independent sample t-tests, variance analyses, Friedman and Mann-Whitney U tests. The significance level was set at 5%. Each preparation increased the canal volume and dentin removal while decreasing the unprepared root surface. The difference between the systems became significant after preparation with size 35 instruments (p<0.05). Regarding canal transportation and centering ratio, the difference was insignificant (p>0.05). The first preparation step (glide path + size 25 instrument) was significantly faster in the OneReci group (p<0.05). Preparation with size 25 instruments of the systems appeared to be safe with similar shaping performances. Larger apical preparation promoted significantly higher dentin removal, volume increase, and prepared surface area in WOG.

Comparison sealing ability in three bioceramic sealers applied in hydraulic condensation technique by using micro-computed tomography

Background/purposeSealing ability in root canal obturation has always been a key concern for endodontic success. The purpose of this study was to analyze the percentage of voids in root canal space obturated by using single cone hydraulic condensation with different root canal sealers and to compare those with AH Plus sealer. Materials and methodsExperiments were conducted using twenty 3D-printed upper first premolars. After the buccal root canals were prepared using Ni–Ti rotary instruments, the teeth were divided into four groups: the AH Plus, BC sealer, BC sealer HiFlow, and Endoseal MTA groups. All buccal canals were obturated by single-cone hydraulic condensation. All specimens were scanned using micro-computed tomography and the percentage volume of the voids inside and outside the filled materials (Vin and Vout) at three different canal depth intervals were calculated by a Bruker micro-CT software. Differences according to root canal sealers were evaluated statistically using the Kruskal–Wallis test and the Wilcoxon Rank Sum test at a significance level of 0.05. ResultsThe results indicated that most of the voids were presented near the interface (Vout), the Vin is very small and not significant different between groups. The Vout decreased in the following order: AH Plus(1.837% ± 1.226%)≅BC sealer (1.225% ± 0.836%)>BC sealer Hiflow(0.349% ± 0.071%)>Endoseal MTA(0.203% ± 0.049%) ConclusionFor the percentage volume of voids between the root canal filling material and root canal surface, though the BC sealer Hiflow is slightly larger than Endoseal MTA, which is still much less than BC sealer and AH Plus.

Optimization of automated preparation of long oval-shaped root canals using supplementary instrumentation.

This study compared the preparation of long oval-shaped root canals using WaveOne Gold and XP-endo Shaper systems, both supplemented or not with manual instrumentation. Twenty-four long oval-shaped canals of mandibular incisors were distributed into two groups according to the instrumentation: WaveOne Gold Primary or XP-endo Shaper systems. All root canals were manually instrumented with a size 25 K-file after automated preparation. The specimens were scanned by using a micro-CT device (17.42 µm) before and after automated preparation and manual instrumentation. The increased surface of the root canal and the percentage of untouched areas were assessed. Both WaveOne Gold and XP-endo Shaper systems increased the root canal surface and had similar untouched areas (p>0.05). Supplementary instrumentation increased the surface of the root canal and decreased the untouched walls (p<0.05). WaveOne Gold and XP-endo Shaper systems provided a similar preparation of long oval-shaped canals and manual instrumentation improved their preparation.

Effect of Voxel Size of Micro-CT on the Assessment of Root Canal Preparation

The aim of this study was to assess the influence of micro-computed tomography (micro-CT) voxel size on evaluation of root canal preparation using rotary heat-treated nickel-titanium files. Curved mesial root canals of mandibular molars were prepared using ProDesign Logic 30/.05 (PDL) or HyFlex EDM 25/.08 (HEDM) (n=12). The specimens were scanned using micro-CT with 5μm of voxel size before and after root canal preparation. Images with sub-resolution of 10 and 20μm voxel sizes were obtained. The percentage of volume increase, debris and uninstrumented root canal surface were analyzed in the different voxel sizes. Data were compared using unpaired Student’s t-test and ANOVA statistical tests (α=0.05). No differences were observed for percentage of volume increase, debris and instrumented surface between the root canals prepared by PDL and HEDM (p&gt;0.05). Both systems promoted higher percentage of debris in the apical third compared to the middle third (p&lt;0.05). After instrumentation using PDL the percentage of uninstrumented surface was highr in the apical third than middle third only when analysis were performed at 5µm (p&lt;0.05). When comparing the different voxel sizes (5,10 or 20µm), both groups showed different means for the variables, with no significant difference (p&gt;0.05). PDL and HEDM had similar root canal preparation capacity. Micro-CT images using different voxel sizes did not influence the results of volume increase and debris evaluation. However, images at 5µm showed greater accuracy to evaluate the percentage of uninstrumented surfaces.

Dislodgement pushout resistance of five bioceramic root-end filling materials.

This study evaluated the dislodgement push-out resistance of five bioceramic materials. One hundred single-rooted teeth with one canal had the apical 3 mm and crown resected to create a 14 mm standardized length. The canals were instrumented to an apical size 80 with a 3 mm root-end preparation made with ultrasonic diamonds. The prepared roots were randomly divided into 5 root-end restorative groups (n=20). ProRoot MTA, Biodentine, EndoSequence Root Repair Material, EndoSequence Fast Set Putty, and EndoSequence BC Sealer with each material placed following manufacturer's instructions and stored at 100% humidity for 2 weeks. An apical-to-coronal static testing load with the identified dislodgement force converted into MPa with mean results analyzed with Kruskal-Wallis and Dunn's post hoc tests (α=0.05). ProRoot MTA and Biodentine displayed similar push-out stress resistance and exhibited significantly greater stress resistance than the similar Endosequence materials. However, all materials failed cohesively and were not dislodged from the root canal surface.

Effect of laser irradiation protocols on temperature, roughness, and morphology of the root surface after root-end resection

This study evaluated the effect of laser irradiation protocols using Thera Lase Surgery (TL), at 2.5 W (2.5) or 2.7 W (2.7), and Gemini (GE), at 1.2 W (1.2) or 1.5 W (1.5) of potency, on the root-end resection surface, in relation to external root temperature, roughness, and surface morphologic changes after the treatments, in the areas near to the root canal (RC) or external root surface (ER). Fifty teeth were endodontically treated and the root-end were resected 3 mm away from the root apex. The specimens were randomized into 5 groups (n = 10), according to the laser irradiation protocol: Control (CO-DW) without irradiation; (TL-2.5) Thera Lase Surgery, 2.5 W; (TL-2.7) Thera Lase Surgery, 2.7 W; (GE-1.2) Gemini, 1.2 W; and (GE-1.5) Gemini, 1.5 W. The external root temperature change was obtained through the difference between the highest value observed during the irradiation and the value at the beginning of the treatment. The surface roughness (µm) was analyzed by confocal laser microscopy and the apical surface morphology was evaluated by scanning electron microscopy, in RC or ER. The temperature change was similar between the irradiation protocols (p > 0.05). CO-DW and GE-1.5 provided the lowest surface roughness (p < 0.05), regardless of the analyzed area. TL-2.7 and GE-1.7 showed more uniform on apical resected morphology and a higher incidence of dentinal tubules occlusion, but only near the root canal (p < 0.05). Root-end resected surface submitted to TL-2.7 and GE1.7 irradiation protocols are more homogeneous and shown higher incidence of closed dentinal tubules near to root canal, despite providing a surface roughness.

Recent root canal irrigation protocol followed by endodontists and postgraduate students of endodontics for root canal therapy in Central India

Background: One of the main purposes of root canal treatment is the complete debridement of root canals. Regardless of the instrumentation technique used 35% or more of the root canal surfaces have been observed to remain uninstrumented. To remove debris and address these uninstrumented surfaces, it is necessary to copiously irrigate the root canal. Many adjuncts have also been developed and being used in an effort to improve the delivery and effectiveness of these irrigants. Although much research have been conducted on different root canal treatment regime and irrigants used in dentistry, only a little data can be found on the widespread practice or acceptance of such methods. Aims and Objectives: The purpose of this survey was therefore to ascertain the current trends in the use of root canal irrigants and irrigation protocol followed by Endodontists and Postgraduate students across Central India (Madhya Pradesh). Material and Methods: A questionnaire-based survey was conducted and participants were asked to fill in responses to some questions regarding their preferences for root canal irrigation like irrigant selection, irrigant concentration, technique used for delivery and activation of irrigants, etc. Results: The majority of the respondents considered both irrigations as well as instrumentation to be of equal importance. Also, the majority of respondents prefer full-strength sodium hypochlorite (5.25%) while only a few have been found to use its lower concentration (3%). Conclusion: It is essential for future prospects to get an awareness of the properties and actions of irrigants and incorporate them into practice for executing a successful endodontic treatment.

Shaping ability of different NiTi rotary systems during the preparation of printed mandibular molars.

This study aimed to evaluate the shaping ability of XP-endo Shaper, TruNatomy and EdgeFile X3 during the preparation of resin-printed mandibular molar mesial root canals. Thirty-three resin-based mandibular mesial roots with two canals, obtained from extracted tooth cone-beam computed tomography (CBCT) image and printed on a three-dimensional (3D) printer, were divided into three experimental groups according to the different nickel-titanium (NiTi) systems used for root canal preparation. The specimens were scanned using CBCT imaging before and after root canal preparation. Then images were registered using a dedicated software and changes in the canal area, volume, untouched canal surface and the maximum and minimum dentine wall wear were calculated. The XP-endo Shaper instruments showed improved shaping ability with lower untouched root canal surface and better preservation of root canal anatomy during the preparation of resin-printed mandibular mesial root canals compared with TruNatomy and EdgeFile X3 systems.

Finite element analysis of maxillary first molar with a 4-wall defect and 1.5-mm-high ferrule restored with fiber-reinforced composite resin posts and resin core: The number and placement of the posts

Statement of problemWhether fiber-reinforced composite (FRC) posts should be inserted in root canals to restore teeth with multiple roots remains unclear. PurposeThe purpose of this finite element analysis (FEA) study was to determine the optimal use of FRC posts in an endodontically treated maxillary first molar with a 4-wall defect and 1.5-mm-high ferrule. Material and methodsEight different models of a maxillary first molar were established: no post (NP), post in palatal root (P), post in distobuccal root (DB), post in mesiobuccal root (MB), posts in palatal root and distobuccal root (P+DB), posts in palatal root and mesiobuccal root (P+MB), posts in 2 buccal roots (DB+MB), and posts in all roots (P+DB+MB). Two types of loading were applied: a force of 800 N parallel to the long axis of the tooth to simulate the vertical masticatory force and another force of 225 N at 45 degrees to the long axis of the tooth to simulate the lateral masticatory force. The equivalent stresses on the external surfaces of the tooth tissue, the internal surfaces of the root canals and in the posts, as well as the maximal shear stresses on the post-core interface and the core-dentin interface, were calculated with FEA. ResultsAll the models showed similar maximal equivalent stress values on the external surfaces of the tooth tissue, and stress concentrations were found at the cervical and furcation area. On the internal surfaces of root canals, an increase of equivalent stress at the middle third of the canals with posts and a decrease at the cervical third were observed. Under vertical loading, the P+DB+MB group showed the largest equivalent stress in the post (76.45 MPa in the palatal post), the DB+MB group showed the largest shear stress on the post-core interface (19.02 MPa), and the MB group showed the largest shear stress on the core-dentin interface (12.07 MPa). Under lateral loading, the P+DB+MB group showed the largest equivalent stress in the post (60.11 MPa in the mesiobuccal post) and the largest shear stress on the post-core interface (13.48 MPa) and the DB group showed the largest shear stress on the core-dentin interface (21.03 MPa). ConclusionsOne post in the palatal canal was found to be appropriate for the FRC post and resin core restoration of a maxillary first molar with a 4-wall defect and 1.5-mm-high ferrule. An additional post in the mesiobuccal canal could help disperse lateral occlusal force and improve retention of the restoration.

Effect of Access Cavity Preparation on Dentin Preservation, Biomechanical Property, and Instrumentation Efficacy: A Micro–Computed Tomographic Study

IntroductionThe purpose of this study was to evaluate the influence of a contracted endodontic cavity (CEC) on dentin preservation, biomechanical property, and instrumentation efficacy of first permanent molars in comparison with a traditional endodontic cavity (TEC). MethodsForty-eight extracted intact maxillary and mandibular first molars were selected and scanned by micro–computed tomographic (micro-CT) imaging. Each tooth type was anatomically matched and assigned to the CEC group or the TEC group (n = 12). After root canal instrumentation with the ProGlider (Dentsply Maillefer, Ballaigues, Switzerland) and WaveOne Gold (Dentsply Maillefer), the specimens were scanned by micro-CT again. Pre- and postpreparation micro-CT imaging was used to evaluate the dentin preservation and instrumentation efficacy. The results on volume and thickness reduction in the coronal dentin and pericervical dentin (PCD), root canal volume and surface area, percentage of unprepared surface area, canal transportation and centering ratio, and canal wall thickness in the “danger zone” were measured and analyzed with the Shapiro-Wilk and independent sample t tests. Based on micro-CT imaging of maxillary and mandibular first molars, CEC and TEC models were constructed on the intact tooth, and 2 different static loads were applied to the occlusal load points. The stress distribution patterns and von Mises stress on the occlusal surface and cervical region were assessed by 3-dimensional finite element analysis. ResultsThe CEC had a significantly lower volume and thickness reduction of coronal dentin and PCD above the alveolar crest compared with the TEC group (P < .05), whereas no difference was observed in PCD below the alveolar crest between the 2 groups (P > .05). There was no difference regarding all instrumentation efficacy outcomes (root canal volume and surface area, percentage of unprepared surface area, canal transportation and centering ratio, and canal wall thickness) in the danger zone between the 2 groups (P > .05). The CEC effectively reduced the maximum von Mises stress and stress concentration area on the occlusal surface and cervical region compared with the TEC. ConclusionsThe CEC preserved more coronal dentin and PCD above the alveolar crest and thus reduced stress concentration on the occlusal surface and cervical region. The CEC had no significant adverse effects on the instrumentation efficacy compared with the TEC given that the instrumentation procedures were performed with ProGlider and WaveOne Gold files.