Post Space Research Articles

Bond strength according to the moment of fiber post cutting fixed with self-adhesive cement to the root dentin.

BackgroundThe fiber posts require a cut in the coronal portion to adjust it to the available clinical space. The cutting of posts cemented may generate tension via bur vibrations of drill on the bonding interface, with the possibility of decreasing the bond strength. Thus, this study aimed to evaluate if the moment of cutting the fiber posts has an effect on its bond strength when fixed with self-adhesive resin cement. Material and MethodsThirty-six bovine teeth were randomly divided into three groups after endodontic treatment and post space preparation (n = 12): IAC- the fiber posts were cutting immediately after cementation; ACR - the fiber posts were cutting after coronal reconstruction with resin; Control - the fiber posts were not cut. The fiber posts were cemented with self-adhesive cement (RelyX U200 - 3M ESPE). After 24 h, the teeth were sectioned perpendicularly and the push-out test was performed in a universal testing machine at a speed of 0.5 mm/min, until failure. Data were analyzed using two-way ANOVA and Tukey’s post-hoc test. ResultsThe effect of moment of fiber posts cutting (p = 0.44) and the interaction between the factors moment of post cutting and third root (p = 0.81) had no significant. The root third factor showed a significant effect (p = 0.01). The bond strength in the apical third was significantly lower than in the middle (p = 0.00) and coronal (p = 0.01) thirds. ConclusionsThe moment of post cutting has no effect on the bond strength of fiber posts fixed with self-adhesive cement to the root canal. Key words:Fiber post, self-adhesive resin cement, push-out bond strength, operative dentistry.

Fracture Resistance of Endodontically Treated Premolars Restored with Flowable Short Fibre-Reinforced Resin Composite-An In Vitro Study.

ObjectiveThis in vitro study aimed to evaluate the fracture resistance of endodontically treated premolar teeth restored with flowable short fibre-reinforced resin composite (FSFRRC) at varying depths within the root canals.MethodsFifty freshly extracted human single-rooted premolars were divided into 5 Groups (n=10), Group I (IN) intact teeth, Group II (P) restored coronally with resin composite only, Group III, IV and V (FSFRRC2, FSFRRC4, FSFRRC6) based on post space preparation to the respective depths of 2, 4 and 6 mm. Root canal treatment was performed for all the samples of Group II, III, IV, V and the teeth were decoronated 2 mm above cementoenamel junction. Following decoronation, post space preparation was done to the depths of 2, 4, and 6 mm (Group III, IV, V). Teeth were restored with FSFRRC (Groups III-V) intra-radicularly and coronally sealed using resin composite. All the teeth were subjected to fracture strength test using Universal testing machine, and mode of failure was analysed. Kruskal-Wallis test followed by Dunn Post-hoc test was conducted for statistical analysis. Statistical significance was set at P<0.05.ResultsAll FSFRRC groups showed higher fracture resistance than teeth restored only with resin composite. FSFRRC4 and FSFRRC6 showed significantly (P<0.05) higher fracture resistance than intact teeth and other experimental groups.ConclusionIntra-radicular placement of FSFRRC increased the fractured resistance significantly and may serve as a promising alternative to conventional post systems to rehabilitate endodontically treated teeth.

Development of dental inspection method: nondestructive evaluation of a dentin-adhesive interface by acoustic emission.

Purpose The state of adhesion between root dentin and a resin composite core material was inspected using acoustic emission (AE).Methods A total of 14 human incisors and premolars were used to prepare "no-adhesive group" and "adhesive group" specimens. For "adhesive group" specimens, a bonding agent was applied to root canal dentin. The entire post space was subsequently filled with a resin composite for both specimen groups. The prepared specimens were fixed onto a jig on which an AE sensor was installed. A zirconia ball was used for the impact test, and a vibration wave generated by the collision was measured by the system using an AE sensor. The obtained data were subjected to time-frequency analysis using analysis software (LabVIEW), and the relationship between the amplitude indicating the loudness and the frequency indicating the sound component was analyzed.Results Zirconia-ball collision tests using AE revealed differences between the groups with respect to the waveform of vibration waves transmitted to the root dentin through the root dentin-resin interface. The time-frequency analysis of the obtained data confirmed that multiple peaks were observed for each specimen in the no-adhesive group, whereas a single characteristic vibration peak was observed for all specimens in the adhesive group.Conclusions The state of the adhesive interface was successfully evaluated by AE. This demonstration is expected to lead to the development of a device that can detect problems at the bonding interface between the prostheses and tooth substances.

Comparative evaluation of fracture resistance of endodontically treated premolars with one remaining cavity wall restored using different techniques and materials: An in vitro study

Introduction: This study was aimed to evaluate and compare the effectiveness of conventional posterior composites, and short fiber-reinforced composites with and without the use of glass fiber post (GFP) and polyethylene fiber post on fracture strength of endodontically treated maxillary premolar teeth. Materials and Methods: Root canal treatment was performed on the sixty extracted maxillary premolars followed by mesio-occluso-distal cavity preparation and removal of the lingual wall. The teeth were randomized into six groups (A1, A2, A3; B1, B2, and B3). In Group A, a conventional posterior composite was used as a core material, and in Group B, short fiber-reinforced composite was used. Groups A and B were divided according to the post systems used. In Groups A1 and B1, 3 mm deep cavities were prepared in the palatal canal and restored with respective core materials. In Groups A2 and B2 GFP were placed in 10 mm post space prepared in the palatal canal and restored with respective core material. While in Groups A3 and B3 polyethylene, fiber post was placed, followed by core build-up with respective core materials. Samples were subjected to fracture resistance testing in the Universal testing machine, and the fractured samples were inspected in stereomicroscope under 20× for identifying fracture patterns. The data were analyzed using one-way ANOVA, followed by post hoc Tukey's test. The failure pattern was analyzed using the Chi-square test. Results: Higher fracture resistance values were seen with groups restored with the post as compared to groups restored without post, but the difference was not statistically significant (P > 0.05). The short fiber-reinforced composite showed higher resistance values than the conventional composite (P 0.05). The use of post resulted in a significantly higher number of favorable fracture of the teeth (P Conclusion: The use of post did not have a profound effect on the fracture resistance but had a positive effect on failure patterns in teeth with one remaining wall. In root canal treated teeth with one wall remaining, the use of either post with short fiber reinforced composite is recommended.

Comparative Study between Nasal Endoscopic Findings and Nose and Paranasal Sinus Computerized Tomography in diagnosis of Nose and Paranasal Sinuses Diseases

Background: Nasal obstruction is common in otorhinolaryngology outpatient visitors. The diagnosis of such compliant is by history, clinical examination and diagnostic procedures. Nasal endoscopy and computerized tomography scan are common diagnostic investigations. Nasal obstruction is either anterior or posterior (nasal septal deviations, hypertrophied turbinate pathological cyst, polyps, mass etc), or postnasal obstruction (hypertrophied turbinate, adenoid hypertrophy, nasopharyngeal cyst or nasopharyngeal tumors).&#x0D; Aim of study: Prospective study to compare endoscopic finding and computerized tomography of nose, paranasal sinuses and postnasal space as diagnostic methods for nasal obstruction and other nose, paranasal sinuses and post nasal space diseases.&#x0D; Subjects and methods: 80 patients with nasal obstruction between the age of 12-60 years old.All patient were examined by nasal endoscopy (rigid or flexible) under local anaesthesia (10 % xylocaine spray and cotton wicks soaked with ephidren 0.5 % and xylocaine 2 % ) and nose, paranasal sinuses and post nasal space C.T. scan,weather without contrast or with it, bone window or soft tissue according to the lesion. &#x0D; Results: Both nasal endoscopy and C.T. scan were an important tools for diagnosis of nasal diseases and complementary to each other.&#x0D; Conclusion: Endoscopic examination of the nose gives a real view of nasal structures, postnasal space, any mass or polyps present.Computerized tomography is an accurate diagnostic method of the Nose, paranasal sinuses and post nasal spaces anatomical variations or pathologies.

Do customized fiberglass posts influence the bond interface in different regions of intraradicular dentin?

This study evaluated the push-out bond strength of customized glass fiber posts in different regions of post space (cervical, middle and apical) submitted to mechanical cycling. Forty single-rooted human premolar teeth were submitted to endodontic treatment and divided into four groups, according to the type of fiberglass posts installed: customized or non-customized posts. Half of the samples were submitted to 1,200,000 mechanical cycles. Samples sections of approximately 1.3 mm thickness were obtained from each regional third and the samples were subjected to push-out bond test. Data were analyzed by two-way repeated measures ANOVA and Tukey's test (p = 0.05). There was no statistically significant difference between customized and non-customized fiberglass posts at the cervical region, regardless if the mechanical cycling was performed. (p = 0.18). In the middle third, the highest value of bond strength was observed in the non-customized group without mechanical cycling (12.90 ± 6.88 MPa), but it was not significantly different from the respective aged group (7.58 ± 4.72 MPa) (p > 0.05). Similar results observed in the apical region, where lower values were found for the customized groups. For customized fiberglass posts, the cervical region showed higher values of bond strength compared to the middle and apical thirds (p < 0.05) with or without mechanical cycling. The customization of fiberglass posts is not an essential clinical procedure since it does not improve the bond strength of fiberglass posts to dentin, independent of the mechanical cycling procedure.

Influence of Propolis, Ozone and Photodynamic therapy in root canal disinfection on resin bond strength to radicular dentin.

The aim of the present study was to assess post space disinfection using different irrigants and their effect on radicular dentin bond to SERC. Forty single rooted mandibular 2nd premolars were collected and disinfected. All samples were decoronated maintaining root length of 12 mm and embedded vertically in acrylic resin. Shaping of the canal was performed using reciprocating system. Canals were dried using paper points and obturated with gutta percha via lateral condensation. Peso-reamers were used to create post space up to 10 mm. The post space was irrigated with 1% NaOCl before being randomly allocated into four groups (n = 10) according to different methods of canal disinfection. Samples in group 1 were subjected to photoactivated disinfection (PAD), group 2 irrigated with ethanol based propolis group 3 disinfected using ozone and group 4 irrigated with 2.25 % NaOCl with 17 % EDTA and ECL. GFP was fitted using SERC. Each sample was cut into 1 mm from coronal, middle and apical and subjected to pushout bond strength (PBS) via universal testing machine. Fracture analysis were confirmed by stereomicroscope at 40x magnification. For comparison of means, Analysis of variance (ANOVA) and Tukey multiple comparison test was used maintaining the level of significance at p < 0.05. The highest PBS at all three levels were found in group 4, canal disinfected with 2.5 % NaOCl with 17 % EDTA and ECYL. Whereas, the lowest PBS was observed in group 1. Inter group comparison, prosthetic space disinfected with propolis extract showed no significant difference to group 4 canal disinfected with 2.5 % NaOCl with 17 % EDTA and ECYL at all three levels (p > 0.05). Intra group comparison in all experimental groups showed no significant difference was noted in coronal and middle thirds of group 1, group 2 and group 3 respectively (p > 0.05). 2.5 % NaOCl with EDTA and ECL treatment (group 4) remains the gold standard when used as a final canal irrigant. Propolis can be used as potential irrigant for canal disinfectant provided if the composition becomes standardized.

Effect of irrigation protocol during post space preparation on the dentin adhesive interface: An in vitro study

Statement of problemThe post space must be prepared with techniques that do not interfere with the bond strength. These techniques are related to the availability of opened dentinal tubules and incidence of residue among the dentin, the adhesive, and the cement. Nevertheless, the effect of different irrigants during endodontic instrumentation is unclear. PurposeThe purpose of this in vitro study was to assess the incidence of residue, the number of opened dentinal tubules, and the bond strength of the cementation system to root dentin of post space after 3 different irrigation protocols. Material and methodsThe roots of bovine incisors were obturated, prepared to receive a fiber post, and divided into 3 groups as per the irrigation protocol: without irrigation, with alternating irrigation, and with continuous irrigation. Thirty roots (n=10) were evaluated by using scanning electron microscopy to assess the incidence of residue (×100 magnification) and the number of opened dentinal tubules (×2000 magnification). The fiber posts were cemented, and the remaining specimens (n=10) were subjected to pushout testing and failure mode evaluation. ResultsAll protocols presented a similar incidence of residue, regardless of the post space third (P>.05). The irrigation protocol without irrigation had the lowest number of opened dentinal tubules in the cervical and middle thirds (P<.05). The number of opened dentinal tubules was similar in all protocols in the apical third of the post space (P>.05). The irrigation protocol without irrigation had the lowest bond strength values in the cervical and middle thirds (P<.05). The irrigation protocol with continuous irrigation had the highest bond strength values in the apical third (P<.05). ConclusionsPost space preparation without irrigation negatively affected the bond strength of the resin cementation system to root dentin.

Effect of Dentin Pretreatment with Chlorhexidine on Push-Out Bond Strength of Composite Restorations in Severely Damaged Primary Anterior Teeth

Objectives:Achieving durable restorations with adequate strength in severely damaged primary anterior teeth in children is a priority. The aim of this study was to investigate the effect of dentin pretreatment with chlorhexidine on push-out bond strength of composite restorations.Materials and Methods:In this in vitro experimental study, 56 extracted primary anterior teeth were randomly divided into 4 groups: (1) saline and total-etch bonding agent, (2) chlorhexidine and total-etch bonding agent, (3) saline and self-etch bonding agent, and (4) chlorhexidine and self-etch bonding agent. After the application of bonding agents, the post space was filled with Z250 composite resin. Following thermocycling of the samples, the push-out test was performed using a universal testing machine, and the results were analyzed with two-way ANOVA.Results:The mean push-out bond strength values in groups 1 to 4 were 5.7, 8.39, 5.35, and 7 MPa, respectively. Chlorhexidine groups had significant differences with saline groups in bond strength (P<0.05) but there was no statistically significant difference between the self-etch and total-etch bonding agents in the groups (P>0.05).Conclusion:Both types of bonding agents (self-etch and total-etch) exhibited favorable results in radicular dentin of primary anterior teeth; however, pre-treatment with chlorhexidine increased the push-out bond strength of composite restorations in primary anterior teeth.

The influence of different treatments on fiber post and root canal to bond strength of fiber post

Different methods were used to treat the fiber posts and root canals, and evaluated their influence on the bond strength of fiber posts. After thirty extracted human, single-rooted premolars were endodontically treated and post space was prepared in each tooth with post drills, they were randomly assigned into nine groups with 33 fiber glass posts. Different treatment methods for fiber posts and root canals were applied. Following post cementation, slice specimens were prepared. The push-out test was performed using a universal testing machine, and the failure modes were examined with a stereomicroscope. Bond strengths (mean ± SD) were: CC group (7.07 ± 1.51 MPa); CE group (10.57 ± 2.90 MPa); CM group (10.06 ± 3.00 MPa); SiC group (7.23 ± 2.06 MPa); SiE group (10.51 ± 2.26 MPa); SiM group (10.50 ± 2.70 MPa); PC group (9.79 ± 2.79 MPa); PE group (11.70 ± 1.76 MPa); PM group (11.06 ± 3.17 MPa). The bond strength of polydopamine group was significantly higher than silane group and control group (p < 0.05). NaClO/EDTA group had higher bond strength than the MTAD group, and both were higher than the control group (p < 0.05). Combined treatment of fiber post and root canal was more advantageous to improve the bond strength between fiber post and root canal. Surface polydopamine functionalization was confirmed to be a reliable method for improving the bond strength of fiber posts. The effect of 5.25% NaClO + 17% EDTA solution on the bond strength is more significant than MTAD solution. When the fiber posts were treated with PDA and the root canals were treated with NaClO/EDTA, the best bond strength can be obtained. In this experiment, fiber posts and root canals were treated separately. The aim of this paper is to explore the influence of different treatment methods on the bond strength of fiber posts, in order to screen out the most effective processing methods and provide theoretical guidance for the clinical application.

Exploring MRI based radiomics analysis of intratumoral spatial heterogeneity in locally advanced nasopharyngeal carcinoma treated with intensity modulated radiotherapy.

BackgroundWe hypothesized that spatial heterogeneity exists between recurrent and non-recurrent regions within a tumor. The aim of this study was to determine if there is a difference between radiomics features derived from recurrent versus non recurrent regions within the tumor based on pre-treatment MRI.MethodsA total of 14 T4NxM0 NPC patients with histologically proven “in field” recurrence in the post nasal space following curative intent IMRT were included in this study. Pretreatment MRI were co-registered with MRI at the time of recurrence for the delineation of gross tumor volume at diagnosis(GTV) and at recurrence(GTVr). A total of 7 histogram features and 40 texture features were computed from the recurrent(GTVr) and non-recurrent region(GTV-GTVr). Paired t-tests and Wilcoxon signed-rank tests were carried out on the 47 quantified radiomics features.ResultsA total of 7 features were significantly different between recurrent and non-recurrent regions. Other than the variance from intensity-based histogram, the remaining six significant features were either from the gray-level size zone matrix (GLSZM) or the neighbourhood gray-tone difference matrix (NGTDM).ConclusionsThe radiomic features extracted from pre-treatment MRI can potentially reflect the difference between recurrent and non-recurrent regions within a tumor and has a potential role in pre-treatment identification of intra-tumoral radio-resistance for selective dose escalation.

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

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

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

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

Effects of 1-Ethyl-3-(3-Dimethylaminopropyl) Carbodiimide on Adhesion of Posts in Teeth Obturated With Different Sealers.

The aim of this study was to evaluate the effect of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) on bond strength of fiberglass posts in root canals obturated with different endodontic sealers. Seventy-eight mandibular premolars were obturated with three sealers (n=26): Endofill (END), AH Plus (AHP), and Endosequence BC Sealer (EBS). After preparation of the post space, two subgroups were formed according to the cementation of the posts (n=13): with EDC (EDC), and without EDC (control - CON). The specimens were submitted to a pull-out test, failure mode classification, and root canal surface evaluation by scanning electron microscopy after post displacement. Regarding the bond strength, a significant difference between the EDC and CON subgroups occurred only in the END (p=0.001). No difference was detected among the CON subgroups (p=0.339). However, among the EDC subgroups, AHP presented significantly higher values (END versus AHP: p=0.001; AHP versus EBS: p=0.016). Upon classification of failure modes, score 1 (≥ 50% of cement) was the most commonly observed, except for the END + EDC. Remains of endodontic sealers and resin cements were found in the cervical third, but without statistical difference (p=0.269), while in the middle third, difference occurred (p=0.004). In conclusion, EDC decreases bond strength when associated with END sealer, without changing the failure mode between the resin cement and fiberglass post. The best performance was observed when EDC was combined with AHP sealer.

Influence of sodium hypochlorite/etidronic acid combination and SmearOFF on push-out bond strength of fiber posts to root dentin.

The aim was to evaluate the effects of different irrigation protocols on the bonding ability of fiber posts on root canal dentin through push-out test and the dentin tubule penetration of luting cement by confocal laser scanning microscope (CLSM). Forty-eight single-rooted premolars were divided into six groups (n=8) based on post space irrigation protocols: Saline 0.85%; Etidronate 18% (HEBP); EDTA 17%; NaOCl 5.25%+EDTA 17%; NaOCl 2.5%/HEBP 9% combination; SmearOFF. Two specimens per group were assessed with CLSM. The push-out test and the failure analysis were performed. Whilst EDTA had the highest bond strength at the coronal and middle thirds, it was not statistically significant compared to saline, HEBP, and NaOCl/HEBP at the middle third (p>0.05). Cement/dentin adhesive failures were predominant (41.9%) and the intratubular fluorescence intensity was significant among the groups (p<0.05). EDTA resulted in highest bond strength values and dentinal penetration.

The use of posts in endodontically treated teeth among Nepalese Prosthodontists.

Introduction: One of the most studied and researched subjects in dentistry is the restoration of endodontically treated teeth. The success of an endodontically treated tooth depends not only good endodontic therapy but is equally if not more dependent on the nature, type, and execution of post-endodontic restorations. The purpose of this study was to know the opinions, techniques, and materials used by Nepalese Prosthodontists for restoring endodontically treated teeth with a post.&#x0D; Materials and Methods: A nationwide survey was performed among Nepalese Prosthodontists through electronic communication media by distributing a questionnaire to find out the various treatment strategies, post types, and materials being used by them. Descriptive statistics were used to analyze the responses given by the Prosthodontists by using SPSS statistical software package (version 21.0).&#x0D; Results: A total of 69 returned questionnaires out of the 114 sent were included in the study. The majority of the respondents were in the age group of 31-40 yrs (70.6%, N=48). 51% of the respondents were male and 49% were female. Out of the responses analyzed, 91% (N=63) think that the primary purpose of a post is to retain a core. The quantity of remaining tooth structure affects the decision to place a post (98.5%, N=68). The ideal post length for 81.2% (N=56) respondents was 2/3rd the root length. 55% (N=38) of respondents think that 4-5mm of apical Gutta Percha should be left during post space preparation. The preferred type of post was custom cast metal post for 69.5 % (N=48) and prefabricated fiber-reinforced post for 66.6% (N=46).55% (N=38) of respondents preferred the passive type of post. Out of the respondents, 72% (N=50) were using Glass Ionomer Cement for cementing cast posts and 91% (N=63) of them were using resin cement for fiber-reinforced posts. The most popular core build-up material was dual-cured composite resin (63.8%, N=44).&#x0D; Conclusion: Although the results obtained cannot give a definitive guide for restoration of endodontically treated teeth with a post, it pictures how the Nepalese Prosthodontists are practicing posts for restoring endodontically treated teeth. The varied responses obtained here can be taken into consideration to conclude that the preference of techniques and materials depends upon the individual clinician and the clinical scenario.

Effect of NaOCl and EDTA as Post Space Cleansing Solutions on the Bond Strength of Resin Cements to Root Canal Dentin (An in vitro Study)

Aims: To evaluate the regional bond strength of four resin-based luting cements to post space dentin after irrigating with different irrigant solutions regimens. Materials and Methods: Eighty extracted human lower premolars were decoronated, instrumented, and obturated. Post space was prepared in each root, then randomly divided into four groups (n=20) according to the final irrigation regimen for the post space, Gp.1: distilled water (DW) control; Gp.2: 5.25% NaOCl+DW; Gp.3: 17%EDTA+DW; Gp.4: 5.25%NaOCl+17% EDTA+DW. Each group was further subdivided into four subgroups (n=5) according to the luting cements, Gp.(1,2,3,4)A (Vivaglass®Liner); Gp.(1,2,3,4)B (PermaCem®-Dual); Gp.(1,2,3,4)C (Variolink II); Gp.(1,2,3,4) D (LuxaCore®Z-Dual), then each post-space was sectioned horizontally into three slices. A push-out test was performed to measure regional bond strengths and the fracture modes was evaluated using a stereomicroscope. Results: The use of 5.25% NaOCl+17% EDTA+DW result in higher bond strength than other treatments. While the control group gives the lowest. (LuxaCore®Z-Dual) showed the highest bond strength than other resin cements. (Vivaglass®Liner) gives the lowest bond strength. The regional bond strengths decreased significantly toward the apical third. The failure mode recorded was mostly adhesive in nature except for groups (3D,4D) showed some mixed failure at the coronal third. Conclusions: NaOCl+ EDTA flush had a profound effect on resin bond strength to radicular dentin. (LuxaCore®Z-Dual) composite core buildup material exhibited the higher regional bond strength to radicular dentin. The regional bond strength decreased from coronal to apical direction.

“A COMPARATIVE EVALUATION OF FRACTURE RESISTANCE OF BADLY MUTILATED ANTERIOR TEETH RESTORED WITH THREE DIFFERENT NOVEL POST CORE SYSTEM: AN IN VITRO STUDY”

Aim A study was aimed to compare the fracture resistance and the mode of failure of endodontically treated teeth reestablished with various fiber post-center frameworks. Method 60 extracted permanent maxillary central incisors selected and biomechanical preparation performed by Conventional step back technique and Obturated by manual lateral condensation technique with guttapercha using AH plus root canal sealer .Teeth randomly assigned into four experimental groups The access cavities were sealed with packable composite restoration.Crown preparation with shoulder of 1mm was prepared followed by reduction of crown high to 8mm from shoulder margin. The post space arrangement was finished with Peeso-Reamer up to number 4 size to a profundity of 10 mm. The fiber present was then applied on a stature of 4 mm over the tooth edge. Post was solidified with oneself fix glue tar concrete. The example with tempered steel square was mounted on an uncommon apparatus on a PC controlled Universal Testing Machine. The compressive burden was applied with 1 mm width, ball-finished steel compressive head at an edge of 130 to the long hub of the tooth. Result The results showed that the fracture resistance of group C (DT light post and Core Flo DC) was significantly higher than the other two groups. Group a (Control) had the least fracture resistance. Conclusion DT lightpost and Core Flo DT post-core system, making it one of the best combinations to be recommended for the treatment of badly mutilated teeth.

Microcomputed tomography evaluation of contamination with endodontic obturation material remnants in teeth with different root canal anatomy after post space preparation

Statement of problemWhether the amount of the endodontic obturation material remnants in a root canal prepared for a post is related to variations in the anatomic shape of the canal or whether it varies in different parts of the post space is unclear. PurposeThe purpose of this in vitro study was to estimate the extent of root canal contamination with remnants of the obturation material after post space preparation in relation to the anatomic shape of the root canals by means of microcomputed tomography. Material and methodsFifty freshly extracted teeth were divided into 5 test groups with respect to the root anatomy of different tooth types. The root canals were shaped and obturated with gutta percha. The space for the glass fiber post was prepared with standardized drills, and all specimens were scanned by microcomputed tomography. The areas of residual obturation material on the root canal walls in the coronal and apical parts of the prepared post space were estimated by using a 3D visualization software program. Parametric and nonparametric dispersive analysis (analysis of variance and Kruskal-Wallis) and Wilcoxon tests were used for statistical data evaluation (α=.05). ResultsThe estimates of the root canal surface areas contaminated with residual obturation material after post space preparation were significantly larger in premolars (P≤.01), as compared with mandibular incisors and with the palatal roots of maxillary first molars. The contamination areas in different parts of the root canal (apical and coronal) reported significant differences within and between the test groups. ConclusionsThe extent of root canal contamination with remnants of endodontic obturation material after post space preparation was related to the anatomic shape of the roots and varied in the coronal and apical parts of the prepared post space.

Influence of different photosensitizers on push-out bond strength of fiber post to radicular dentin

To evaluate the effect of different photosensitizer on extrusion bond strength of glass fiber post to radicular dentin. Forty maxillary and mandibular central incisors were disinfected and decoronated. Mechanical instrumentation of canal was performed using protaper NiTi. Shaping and cleaning of canal comprised of S1, S2, SX with finishing files F1 and F2, followed by continuous irrigation. Canals were dried and obturated with gutta percha. Peso reamers were used to prepare post space. Based on the photosensitizers (PS) used, the samples were divided into three groups (n = 10). Group 1: treated with methylene blue photosensitizer (MBP) at 50 mg/l, Group 2: Curcumin photosensitizer (CP) at 500 mg/l, Group 3: canal space was filled with Toluidine blue photosensitizer (TB) at 100 mg/l. All photosensitizers were activated using different lasers. The samples in group 4 (control) were irrigated using 5.25% sodium hypochlorite (NaOCl) + 17% ethylenediamine tetra acetic acid (EDTA). Posts were cemented and teeth were sectioned into coronal, middle and apical sections. All sections were placed in universal testing machine to evaluate extrusion bond strength in megapascal (MPa). Fracture pattern analysis of samples were seen under stereomicroscope at 50x magnification and categorized into adhesive, cohesive and admixed. Assessment of extrusion bond strength was performed by one-way analysis of variance (ANOVA) and Tukey multiple comparison test (p = 0.05). The highest bond strength was achieved in group 2, including samples treated with curcumin photosensitizer (CP) at all three root levels; cervical (9.01 ± 1.62 MPa), middle (7.95 ± 0.75 MPa) and apical (5.81 ± 0.15 MPa). Whereas, the lowest extrusion bond strength was observed in group 4 (canal irrigated with conventional 5.25% NaOCl +17% EDTA) at coronal (6.10 ± 1.77 MPa), middle (5.11 ± 0.75 MPa) and apical one-thirds (3.65 ± 0.14 MPa). Intra group comparison revealed decrease in extrusion bond strength from coronal to apical direction. Moreover, both group 2 and group 3 showed statistically significant difference to samples in control group and group 1. (p < 0.05). TB and CP at concentration of 100 mg/l and 500 mg/l has the potential to be used as an alternate to conventional cleaning regime. TB and CP at this concentration when activated with PDT is likely to improve extrusion bond values.