Aim: This study was aimed to analyze the stress generation and distribution for “polyether ether ketone (PEEK)” and metal cobalt-chromium (Co-Cr) at different locations of the tooth using finite element analysis (FEA), when they are casted-off as “Richmond crowns.” Materials and Methods: The model of the tooth was designed using “computer-aided design/computer-aided manufacturing” followed by generating the “Mesh” of the tooth to analyze the stress caused by applying vertical and oblique loads of 100N and 40N, respectively, in cubical nodes for both PEEK and metal endodontic post-based Richmond crown. The “3-dimensional von Mises criteria” was used to compare stresses of both elements using FEA. The material properties for each component were designated by respective modulus of elasticity and Poisson's ratio. The statistical test of the stress generation in various locations of PEEK and Metal (Co-Cr) Richmond crown was done by independent t-test. Results: From the FEA analysis of Richmond crown, it is evident that maximum stress was generated by “Metal” of about 66.418 MPa when compared to “PEEK” (15.826 MPa). “PEEK Richmond crown” produced minimal stress on the tooth and the other surrounding regions than “Metal Richmond crown” with a statistically significant difference (P < 0.05). Conclusion: The results proved that the “Metal Richmond crown” postsystem had a tendency to produce more stress on the tooth and the other surrounding regions than the PEEK. The FEA proved the pros of using “PEEK post Richmond crown,” which is a big boon for the modern era dentistry.

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Background: The eugenol from zinc oxide eugenol (ZnOE) sealer tends to diffuse to the periapical region resulting in inflammation. Several modifications of ZnOE sealer have been formulated to minimize the inflammatory potential of the ZnOE sealer. Petasites hybridus contains petasin which possesses anti-inflammatory property used in treatment of migraine and allergic rhinitis. Aim: The aim of the study was to evaluate the anti-inflammatory property of petasin-incorporated ZnOE sealer on zebrafish. Materials and Methods: The study has been reviewed and approved by the Institutional Review Board (SRMU/MandHS/SRMDC/2018/S/025) and by the in-house Institutional Animal Ethics Committee (IAEC) of Pentagrit Research Lab and conducted with compliance to ICH harmonization and principles for animal housing and handling (IAEC Study No: 215/Go06/IAEC). The samples were implanted in the caudal portion of the zebrafish. The samples (n = 50) were divided into five groups (n = 10) – Group 1: incision only (negative control), Group 2: zinc oxide (ZnO) (positive control), Group 3: ZnO + eugenol and petasin in ratio of 10:1, Group 4: ZnO + eugenol and petasin in ratio of 5:1, and Group 5: ZnO + eugenol and petasin in ratio of 1:1. The experimental groups were further subdivided into two subgroups based on time intervals at 24 h and 48 h. The tissue samples were assessed using smear pathology test, and the percentage of inflammation was evaluated. The data were statistically analyzed using SPSS software version 22.0 with a significance level fixed as 5% (α = 0.05). Results: The presence of inflammatory cells and congestion of arterioles were taken as the criteria to assess inflammatory action. It was maximum in ZnOE sealer followed by ZnOE sealer modified with the addition of petasin to eugenol in the ratio of 10:1, 5:1, and 1:1, respectively. Conclusion: The addition of petasin extract to ZnOE reduces the inflammation potential of ZnOE sealers. ZnOE sealer containing eugenol and petasin in the ratio of 1:1 showed a maximal reduction in inflammation.

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Context: Pulpotomy is a procedure in which part of an exposed vital pulp is removed, usually as a means of preserving the vitality and function of the remaining part. Aim: The aim is to compare the effectiveness of Dycal (CH), EndoSequence, and Titanium-prepared platelet-rich fibrin with EndoSequence (T-PRF) as pulpotomy agents in mature permanent molars with irreversible pulpitis. Settings and Design: Sixty permanent mandibular molars with carious exposure and symptoms of irreversible pulpitis were randomly allocated to three groups. Subjects and Methods: Full pulpotomy was performed using Dycal, EndoSequence, and T-PRF with EndoSequence as pulpotomy agents. Pain intensity was analyzed using a Numeric Rating Scale score at baseline 24 h, 7 days, 6 months, and 1 year. The clinical and radiographic evaluations were done at 6 months and 1 year. Statistical Analysis: Nonparametric tests (Kruskal–Wallis, Chi-square) were applied to analyze the data as the normality test does not follow a normal distribution. Results: T-PRF and EndoSequence showed effective results when compared clinically, and there was no significant difference between radiographic success rates among the three groups at (P = 0.325 at 6 months, 0.466 at 12 months) follow-up. Conclusion: T-PRF and EndoSequence showed higher success rates among Dycal, EndoSequence as pulpotomy agents in teeth with irreversible pulpitis.

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Aims: This mass spectrometry study investigated the diffusion of hydroxyl and calcium ions from a calcium hydroxide intracanal medicament (Pulpdent^®) when used alone or mixed in equal parts with a steroid–antibiotic paste (Ledermix^®). Materials and Methods: The pH (using pH meter) and calcium ion concentration (using inductively coupled plasma-mass spectrometry) of the diffused medicaments were assessed using endodontically prepared human extracted teeth with either a sealed or a patent apex, at time intervals of 1, 3, 8, 24, and 168 h. Statistical Analysis: A one-way ANOVA was used to explore differences between and within groups, with Tukey–Kramer/Games–Howell posttests. Results: In both situations tested, Pulpdent^® showed greater release of both calcium and hydroxyl ions than when mixed in equal parts with Ledermix^®. Greater initial release of both ions occurred in roots with a patent apex, but by 1 week there was no significant difference between the two. If a 50:50 combination of Pulpdent^® paste and Ledermix^® paste is used, there is a lower release of calcium ions and hydroxyl ions than using Pulpdent^® paste alone. Conclusion: With both Pulpdent^® paste alone and Pulpdent^® paste mixed equally with Ledermix^® paste, the major pathway for movement of hydroxyl ions and calcium ions is diffusion through the dentine of the root, with the apex playing only a minor role.

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Background: Any solution of chemical nature when combined will result in the formation of a precipitate, which in the root canal system will interfere with the hermetic seal. In clinical practice presence of any precipitate, especially carcinogenic in nature, should be eliminated. Aim: To evaluate whether final irrigation with different agitation protocols will remove the precipitate formed following lidocaine hydrochloride and sodium hypochlorite combination at the coronal, middle, and apical-root thirds. Materials and Methods: Forty-four uniradicular teeth were standardized at 17 mm. All specimens were injected with 2% lidocaine hydrochloride and 2.5% sodium hypochlorite, followed by mechanical instrumentation using rotary files. Further, specimens were arbitrarily divided into four groups (n = 11) based on the final irrigation protocol: Group 1: No irrigation; Group 2: Manual irrigation; Group 3: Mechanical irrigation; Group 4: Ultrasonic irrigation. Samples were sectioned and Field Field Emission Scanning Electron Microscopic (FESEM) analysis of the canal wall was done at coronal, middle, and apical thirds. Results: FESEM images revealed occluded dentinal tubules with the presence of precipitate seen in all-thirds of each specimen. Conclusion: No irrigation protocol was successful in removing the precipitate formed; but when compared ultrasonic irrigation had the least precipitate seen at-coronal,-middle and apical thirds.

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Aims: The present study aimed to evaluate the color and translucency changes of the feldspathic porcelain samples made using the conventional or computer-aided design/computer-aided manufacturing (CAD/CAM) methods after immersion in staining solutions and laser bleaching. Materials and Methods: A total of 72 samples of feldspathic porcelain were fabricated using the conventional (n = 36) or CAD/CAM (n = 36) methods. Afterward, each group was randomly divided into three subgroups (n = 12), which underwent exposure to coffee, orange juice, or distilled water for 6 weeks. Then, the samples underwent diode laser-assisted bleaching. A spectrophotometer assessed the samples' color and translucency preintervention, after staining, and after bleaching. Statistical Analysis Used: One-way and two-way analysis of variance and independent t-test were used. The significance level was 0.05. Results: Staining for 6 weeks significantly changed the color of both types of feldspathic porcelains. Furthermore, there were significant differences between the ceramics made using different methods and immersed in different staining solutions (P < 0.001). Furthermore, laser-assisted bleaching changed the color of immersed specimens significantly (P = 0.005). However, there were no significant translucency changes in all the subgroups after staining (P = 0.215) and laser bleaching (P = 0.325). Conclusions: The staining-induced discoloration of all the subgroups was in the clinically acceptable range (ΔΕ<3.3). In addition, bleaching could effectively remove the stains in both types of ceramics while not affecting the primary color. Moreover, the translucency of the ceramics was not affected by staining or laser-assisted bleaching.

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Background: The predictability of direct pulp capping (DPC) depends on the quality of the dentin bridge formation and the inflammatory response to the capping material. Various materials are available with variable success. Aim: The aim of this study is to evaluate histologically the effectiveness of calcium hydroxide, mineral aggregate, and dentin bonding agent when used as DPC in mechanically exposed adult pulp tissue. Materials and Methods: Pulpal exposures were made in 45 intact human premolars, scheduled for extraction for orthodontic purposes. Teeth were capped with hard setting calcium hydroxide (Dycal), mineral trioxide aggregate (ProRoot MTA), and dentin bonding agent (adper Single Bond). The final restoration was done with posterior composites using resin-modified glass-ionomer cement as a base. Pulps of teeth were evaluated histologically at the 15^th and 45^th day for inflammatory cell response and dentin bridge formation according to the criteria described by Cox et al. The statistical analysis of data was done using Chi-square test and P ≤ 0.05 was considered statsiticlly significant. Results: MTA as DPC agent showed milder inflammatory response compared to Dycal and Single Bond. The quality of bridge formation by MTA was similar to Dycal, which took the least time. Adper Single Bond Plus and Dycal showed a significantly higher degree of pulpal inflammation. Among all materials used, Adper Single Bond Plus took the longest time for both the resolution of pulpal inflammation and improvement of the quality of bridge formation. Conclusion: Based on the result, it can be concluded that Dycal and MTA produce similar types of dentin bridge formation when used a DPC agent. Adper Single Bond has the potential to be used as DPC agents, but it takes a longer time for the resolution of inflammation and dentin bridge formation.

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Successful root canal treatment requires a thorough understanding of the normal root canal anatomy and possible variations for each tooth. Variations in the root canal anatomy are frequently associated with complex orientations of pulp tissues and complicating mechanical and chemical debridement. Inability to manage such complications may result in endodontic failure. Mandibular first premolars often exhibit a wide range of anatomic variations, complicating clinicians' treatment. This clinical case report discusses the cone-beam computed tomography (CBCT) diagnosis and nonsurgical management of a taurodontic mandibular first premolar with two roots and four canals under a dental operating microscope (DOM). In endodontically challenging cases, using a DOM and CBCT imaging can help the clinician gain a better understanding of the complex root canal anatomy, allowing the clinician to more efficiently explore, clean, shape, and obturate the root canal system.

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Context: Extracanal and intracanal heating of sodium hypochlorite (NaOCl) improve its pulp dissolution, but limited literature is available on its effect as a combined single irrigant with etidronate. Aim: The aim of this study is to compare the effect of temperature on the effectiveness of NaOCl and continuous chelation protocol on the time required for the dissolution of vital and necrotic pulp. Materials and Methods: Dissolution time of 120 standardized bovine (buffalo) pulp fragments, divided into 12 subgroups based on tissue type (vital/necrotic), irrigant (NaOCl/continuous chelation), and temperature (extracanal, intracanal, and nonheated irrigant), was noted. Conical glass tips mimicking the root canal were considered specimen containers. About 0.2 ml of irrigant corresponding to the irrigation protocol was taken in them and then pulp samples were added to it. Samples were observed using loupes under 2.5 X magnification. Dissolution time was recorded using a stopwatch. The study was approved by the Institutional Ethical Committee (SDC/2019/591). Statistical Analysis Used: Two-way analysis of variance; statistical product and service solutions version 25. The level of significance was set at P < 0.05. Results: Time for pulp dissolution by continuous chelation mixture was significantly more as compared to NaOCl alone in all subgroups. Pulp tissue dissolution for both vital and necrotic pulp was improved by the increase in temperature of both irrigants and dissolution time was more for necrotic than vital tissue. Pulp tissue dissolution was significantly better by intracanal heating as compared to extracanal heating. Conclusion: Although intracanal heating of continuous chelation mixture improves its pulp dissolution capacity significantly as compared to extracanal heating and nonheating protocol but pulpal dissolution capacity of nonheated 5% NaOCl still remains significantly better as compared to intracanal and extracanal heated continuous chelation mixture.

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Background: To evaluate the efficacy of the smear layer removal with Fumaric acid when used in combination with new generation files Hyflex Electrical Discharge Machining (HEDM) file, Neoendo file, and Blueflex file. Materials and Methods: Sixty extracted mandibular premolars with single-canal were selected for this study. Radiographs were taken to confirm the presence of single canal and absence of any type of calcifications, resorption, cracks, and fractures. The teeth were decoronated to a standardized length of 12 mm and working length was determined with ISO #15 K file. After this, teeth were randomly divided into 2 main groups – Control and Experimental group. In Control group, root canal instrumentation was performed with Neoendo, Blueflex, and HEDM files, respectively, along with 1 ml of 17% ethylenediaminetetraacetic acid (EDTA), and in Experimental group, root canal instrumentation was performed with Neoendo, Blueflex, and HEDM files, respectively, along with 1 ml of 0.7% fumaric acid for 1 min. Longitudinal grooves were prepared with slow-speed silicon carbide disc on the buccal and lingual surfaces of each root. Preparation for scanning electron microscope was done and phototmicrographs at ×3000 were taken. Statistical Analysis: The results were analyzed using ANOVA test for comparison of smear layer scores among various groups and Tukey's HSD test was used for paired comparisons of total smear layer scores. Conclusions: On the basis of the present study, Blue flex file along with fumaric acid was found to be best among the groups and Neo endo along with EDTA was the poorest.

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Context: Pretreatment of radicular dentin with chelating agents improves the bond strength of fiber-posts luted with a self-adhesive resin cement. Aims: The aim of this study was to assess the effects of the three chelating agents as final rinse of the postspace on bond strength of fiber posts luted with a self-adhesive resin cement. Settings and Design: This is an in vitro laboratory study. Materials and Methods: Forty-five mandibular premolars were prepared using MTwo rotary system and irrigation was done with 2.5% sodium hypochlorite. Three groups of teeth samples were considered for postspace preparation and irrigated with different solutions: Group 1: 17% ethylenediamine tetraacetic acid (EDTA); Group 2: 7% Maleic acid; Group 3: 1% Phytic acid. This was followed by the luting the posts with RelyX U200. After a week, from each sample, 2 mm thick slices were obtained from each third of the root and subjected to push-out bond strength testing. Statistical Analysis Used: One-way analysis of variance and Bonferroni's Post hoc analysis was used for assessing the results. The statistical significance level was set at P < 0.05. Results: Bond strength values were improved with maleic acid and phytic acid pretreatment with slight or no significant difference between these groups. A final rinse of postspace with EDTA significantly reduced the bond strength. Conclusions: Maleic acid (7%) pretreatment of postspace improved the adhesion of fiber posts luted with a self-adhesive resin cement.

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Background: Long-term use of intracanal medicaments such as calcium hydroxide (CH) reduces the fracture resistance of dentin. Aim: This study aimed to evaluate and compare the compressive strength of root dentin exposed to CH, mixed with various vehicles after 30 days of placement. Settings and Design: Sixty single-rooted extracted human permanent premolars were collected, and complete instrumentation was done. Samples were divided into six groups. Materials and Methods: In Group I, no medicament was placed. In Group II, Group III, and Group IV, the root canals were filled with CH powder mixed with normal saline, distilled water, and local anesthetic solution. In Group V and Group VI, the root canals were filled with Metapaste and RC-Cal. Access cavities were sealed using IRM and were stored for 30 days. Teeth sectioned to obtain a 5 mm thick dentin cylinder subjected to compressive loading to evaluate the fracture resistance using a universal testing machine. Statistical Analysis: Results were analyzed using one-way ANOVA and multiple comparisons using Bonferroni test. Results: Highest mean compressive strength was recorded in Group I followed by Group II, Group IV, Group VI, Group III, and Group V. Conclusions: CH when used as a root canal dressing material will reduce the compressive strength of the teeth irrespective of the form of CH and vehicle.

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Aim: The aim of the study is to evaluate of debris and smear layer formation after using rotary ProTaper Universal, Twisted File, and XP Endo file systems under scanning electron microscope. Materials and Methods: Forty freshly extracted mandibular second premolar teeth were taken to decoronate at the cementoenamel junction to make the remaining root length 15 mm. Specimens were divided into four groups of 10 teeth each, Group I (control) – no instrumentation. Group II – ProTaper Universal rotary file (F2), Group III – twisted file (ISO size 0.25 and 6% taper), Group IV – XP Endo file (ISO size 0.25). During instrumentation, 5 ml normal saline was used as irrigating agent. Grooves parallel to the longitudinal axis of the root were made on the mesial and distal surface of each specimen to split it into two halves and examined under scanning electron microscope at ×1500 and ×5000 magnification. Photomicrographs were taken to evaluate debris and smear layer. Evaluation of photomicrographs was done using a score index. Results: One-way analysis of variance (ANOVA) was used to compare more than one means at a time. Tukey's critical difference followed by ANOVA was used to compare the mean values pair wise. P <0.05 was considered to be statistically significant. Among all the file systems, Group II showed maximum amount of debris (3.50 ± 1.109) followed by Group III (2.83 ± 1.238) and least amount was showed by Group IV (2.65 ± 1.122) at all levels (cervical, middle, and apical third). Among all the experimental groups, Group II showed maximum amount of smear layer (2.75 ± 1.149) followed by Group III (2.40 ± 0.982) and least amount of smear layer shown by Group IV (2.10 ± 0.841) at all levels (cervical, middle and apical third), the result was statistically significant (P < 0.05). Conclusions: At all the levels (cervical third, middle third, and apical third), among all the experimental groups, highest amount of debris and smear layer was formed by ProTaper Universal rotary file followed by Twisted file and least amount showed by XP Endo file system. In all the levels, control group showed highest amount of debris but least amount of smear layer.

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Aims: The study was aimed to evaluate and compare the compressive, diametral tensile, and flexural strengths of three different commercial resin based core materials and to single out the best resin-based core build-up material with respect to their physical properties among ParaCore® (Coltene Whaledent, USA), FlouroCore® 2+ (Dentsply International, USA), MultiCore® (Ivoclar Vivadent, Liechtenstein) with Miracle Mix® (GC America) core used as control. Materials and Methods: One hundred and twenty samples were prepared, of which forty samples (10 of each material) were prepared in cylindrical stainless steel molds (height 6 mm, diameter 4 mm) for compressive strength measurements. Other forty samples (10 of each material) were prepared in cylindrical molds (diameter 6 mm, height 2 mm) for diametral tensile strength measurements. Forty samples (10 of each material) were prepared in stainless steel molds cuboidal in shape (length 25 mm, thickness 2 mm, and width 2 mm) for flexural strength measurements. The samples were tested on a Universal testing machine (Instron Machine 3366, made in the USA). Statistical Analysis Used: One-way analysis of variance was performed to determine any statistically significant differences (P < 0.05) among the resin-based core build-up materials with respect to their three respective strengths. Further, the statistical comparison was made among the four materials using Student's t-test at a significance level of 5%. Results: Based on the results obtained it can be summarized that the ParaCore is the strongest material among all the four materials, followed by MultiCore, FlouroCore2+, and Miracle Mix. The Miracle mix is the weakest among all the materials owing to its inferior strength values. Conclusion: The results of the present study imply that, in consideration of their superior strength values, resin-based core build-up materials, ParaCore, MultiCore, and FlouroCore2+ should be a preferred for use as core build-up material over Miracle Mix in specific clinical situations, in the same order of preference.

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Background: Periapical granuloma and periapical cysts develop as a sequela of inflammation of dental pulp, usually a consequence of an infected root canal. Mast cells (MCs) have most frequently been implicated in the pathophysiology of periapical lesions such as periapical granulomas and cysts. Aims: The present study was undertaken to emphasize the presence and quantification of MCs in periapical lesions (granulomas and cysts) using toluidine blue stain, with an aim to elucidate their role in the pathogenesis of these lesions. Materials and Methods: The study comprised a total of 55 previously diagnosed cases (30 cases of radicular cyst and 25 cases of periapical granuloma) selected from the departmental archives. The MCs were quantified in all the sections in the three zones, namely the epithelial, subepithelial, and deeper connective tissue zones. The results were sent for statistical analysis. Statistical Analysis: Wilcoxon paired t-test and Mann–Whitney U test were applied for intra- and intergroup comparison MCs in different zones of periapical granulomas and radicular cyst, respectively. Results: A statistically significant difference was observed between the two lesions in all the three zones, i.e., epithelial, subepithelial, and in deeper connective tissue zone with P = 0.001. Conclusion: Although MCs were present in all the three zones of both periapical cysts and granuloma, they were predominantly observed in radicular cysts than in periapical granuloma. This suggests a significant role of MC in initiation, development, and progression of these periapical lesions.

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Aim: The aim of this study is to evaluate the smear layer removal efficacy of newer rotary files using scanning electron microscopic analysis at the coronal, middle, and apical third of the root canal. Materials and Methods: In this study, sixty permanent human single-rooted teeth with complete, mature root apices without any anatomic variation having straight patent root canal extracted for periodontal cause were included. The samples were cleaned to remove debris, calculus and rinsed with sodium hypochlorite to remove organic tissue and then stored in distilled water. All the samples were decoronated with the help of carborundum disc at root length of 12 mm to obtain segments similar in length. After this, all the samples were randomly divided into four groups -Protaper universal, Protaper Gold, EDM, and Revo-S. After cleaning and shaping, samples in each group were finally flushed with normal saline. Samples were then dried. Grooves were made into the root in the buccal and lingual portion of the root using a diamond bur and the samples were split longitudinally into two halves using stainless steel chisel and mallet. Preparation for scanning electron microscope was done and phototmicrographs at ×3000 were taken. Result: Chi square test and Kruskal–Wallis test was used for statistical analysis. Result of this study showed that Revo –S was found to be best amongst the groups and EDM was the poorest. Conclusions: Based on the present study, Revo-S files showed the best smear layer removal in the coronal, middle, and apical 1/3^rd of the root canal when compared to other groups. Within the parameters of the study, Revo –S was found to be best amongst the groups and EDM was the poorest. The quality of various files according to ranks of smear layer removal was found to be: Group IV > Group II > Group I > Group III.

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Context: This study was carried out to assess the currently available composite systems in India for resistance to fracture in teeth with large cavities. Aim: To evaluate the fracture toughness of weakened maxillary premolars restored by contemporary composites. Settings and Design: In-vitro study was done in the department of conservative dentistry and endodontics. Materials and Methods: Freshly extracted 44 human maxillary bicuspids were randomly divided into four groups where Group I included intact teeth. The teeth in the other three groups were subjected to a standardized mesio-occluso-distal cavity preparation. The cavities were filled in Group II with bioactive, nanohybrid composite with Giomer chemistry (Beautifil II LS, Shofu Inc., Kyoto, Japan), in Group III with highly filled, nanohybrid composite (Prevest Fusion Universal, Prevest DenPro Limited, Jammu, India) and in Group IV with fiber-reinforced composite with optimized fiber-aspect ratio technology (everX Posterior, GC EUROPE N. V., Leuven, Belgium). All the specimens were then subjected to thermocycling followed by incubation procedures. Fracture resistance was measured in Newton (N) using the universal testing machine. Statistical Analysis Used: Data obtained were tabulated and subjected to one-way analysis of variance (ANOVA) test followed by Tukey's test. Results: Highest mean fracture resistance was observed with Group I (2294.06), followed by Group II (1708.72), Group IV (1195.82), and Group III (825.38). One-way ANOVA test showed a statistically significant difference (P ≤ 0.05) between all the four groups. Post hoc Tukey test was used for intergroup comparison and showed significant difference (P ≤ 0.05) in mean fracture resistance between groups. Conclusion: The results suggest that the highest compressive fracture resistance was shown by Group II (Beautifil II LS composite resin).

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Background: A myriad of materials and procedures have been recommended for restoring the root-filled teeth with significant loss of tooth structure and the most common method being the use of “posts.” Material and Methods: A mesio-occluso-distal preparation was done on eighty intact maxillary first premolars, followed by access preparation and cleaning and shaping with rotary files. All samples were obturated and divided into four groups (n = 20). In Group 1, 3-mm gutta-percha was removed and restored using composite resin; Group 2 – Group 1 + crowns; Group 3 – prefabricated fiber post + crowns; and Group 4 – prefabricated metal post + crowns. All the groups were subdivided into eight groups (n = 10), fractured with 90° vertical and 45° oblique loading by a universal testing machine. Statistical Analysis: Fracture resistance was analyzed and compared by means of two-factorial two-way analysis of variance and Scheffe's post hoc test. Results: Under 90° loading, the fracture load of teeth restored with the Nayyar's composite resin core and crown was greatest. Under 45° loading, the fracture load of teeth restored with prefabricated metallic posts was significantly (P < 0.05) less than that in other groups. Under 45° load, group with fiber post exhibited significantly (P < 0.05) more number of favorable fractures than other groups. Conclusion: Under the conditions of vertical and oblique loadings, fiber post and composite resin core with a full-coverage crown is the most effective restorative modality for protecting the remaining tooth structure in pulpless teeth.

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Aim: To compare the effect of different zirconia surface treatments on cement bond strength to dentine. Materials and Methods: Stick-shaped pre-sintered zirconia (N = 128) were prepared and divided into eight groups (n = 16). Three surface treatments (sandblasting, neodymium-doped yttrium aluminum garnet [Nd:YAG] or carbon dioxide laser irradiation) were applied, either before (later to be sintered) or after sintering. The last test group was sintered zirconia coated with feldspathic veneering ceramic. Sintered zirconia without surface treatment was tested as the control group. Zirconia samples were cemented to dentine using Panavia F2 cement. The micro-shear bond strength was measured after 24 h (n = 8) or 10,000 thermocycling (n = 8). Statistical Analysis: Data were analyzed using one-way analysis of variances and Student's t-tests. Results: Zirconia coated with feldspathic ceramic revealed the highest bond strength (P < 0.001). Presintered zirconia treated with Nd: YAG laser showed a significantly improved bond strength compared to the control group before and after thermocycling. The bond strength after thermocycling was significantly reduced in presintered zirconia treated with Nd: YAG or sandblasting. Adhesive failure at the zirconia-cement interface was the dominant failure type. Conclusions: Surface treatment of presintered zirconia by Nd:YAG laser or coating of the sintered specimens with feldspathic veneering ceramic increased the zirconia-cement bond strength.

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Background: Regenerative endodontic procedures (REP) have the advantage of restoring root canal's native defense ability by re-establishing vital pulp-like tissue. This review aims to determine the overall clinical and/or radiographic success rate (O) of REP (I) in mature permanent teeth (P) and to compare it (C) with nonsurgical endodontic treatment (NSET). Materials and Methods: Sources: PubMed, Web of Science, Embase, EBSCO, Cochrane Central Register of Controlled trials, ClinicalTrials.gov, Clinical Trials Registry-India and OpenGrey. Inclusion: Randomized clinical trials and single-arm prospective studies evaluating the treatment outcomes of REP in mature permanent teeth. Exclusion: Incomplete trials/studies, in vitro studies, animal studies, case reports/series, conference proceedings. Cochrane ROB2.0 and ROBINS-I tools were used to assess the risk of bias. Risk difference (R.D.) between NSET and REP was determined by meta-analysis of the randomized clinical trials. The overall success rate of REP was calculated using data from both randomized clinical trials and single-arm prospective studies. Sensitivity analysis and subgroup analysis were performed. Results: Ten studies (n = 552) were included. R.D between REP and NSET was 0.032 (95% C.I: 0.023–0.087; P = 0.258). Overall success rate of REP was 96.0% (95% confidence interval: 94%–98%). No significant difference was found in sensitivity analysis (P = 0.551), or any of the subgroup analysis (P > 0.05). Discussion: A limited number of randomized clinical trials were available, and only two of them had a low risk of bias. Consistent results were obtained in both types of included studies. Conclusion: Based on a limited number of comparative studies, REP has a similar success rate to NSET in mature permanent teeth. Other: Funding: Nil. Registration: PROSPERO (CRD42020204882).

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