Evaluation of the efficacy of TruNatomy, ProTaper retreatment, and RaCe file systems in retreatment of moderately curved mandibular molars: An in vitro study.

Context: Endodontic retreatment is the first line of treatment in cases of failed primary endodontic treatment. Although associated with challenges such as incomplete removal of obturating material, increased clinical time, and extrusion of apical debris, endodontic retreatment still has considerable success rate in the general population. Aims: The aim of this study was to evaluate and compare the efficacy of TruNatomy, ProTaper retreatment, and RaCe file systems to remove the obturating material, time taken to remove the obturating material, and apical extrusion of debris using cone-beam computed tomography (CBCT). Settings and Design: In vitro study. Subjects and Methods: Forty-five moderately curved mesiobuccal roots of the mandibular molars were instrumented up to #25, 4% taper and obturated with bioceramic sealer and lateral compaction technique. Teeth were divided randomly into three groups (n = 15). Teeth were retreated with TruNatomy, ProTaper retreatment, and RaCe file systems, respectively. Preretreatment and postretreatment CBCT scans were recorded and percentage of obturating material removed was calculated. Time taken to remove the obturating material and apical extrusion of debris was noted. Statistical Analysis Used: Descriptive statistics including percentage, mean, standard deviation, Tukey's post hoc test, Kruskal-Wallis test, and Mann-Whitney Post hoc test were used. Results: The total time needed for the removal of obturating material was comparatively shorter in the RaCe group, followed by the ProTaper retreatment group and TruNatomy group (P < 0.001). TruNatomy files were significantly better in removing the obturating material than the ProTaper retreatment files (P = 0.04). Statically, no difference between RaCe and TruNatomy files was noted. Apically extruded debris was more in the TruNatomy group than in the RaCe and ProTaper retreatment groups (P = 0.01). Conclusions: All tested endodontic files were effective in removal of obturating material, although none could completely remove the filling material and no system could completely eliminate apical extrusion.

An in vitro radiological evaluation of irrigant penetration in the root canals using three different irrigation systems: Waterpik WP-100 device, passive irrigation, and manual dynamic irrigation systems.

Background: Instrumentation and irrigation of the root canal facilitating effective debridement is considered the most important single factor in the prevention and treatment of endodontic diseases. Aim: The aim of the study was to evaluate the depth of penetration of the irrigant depending on the final activation using Waterpik device modified with NaviTip needle, passive irrigation, and manual dynamic activation using the radiopaque solution in conjunction with digital dental radiography. Materials and Methods: Ninety freshly extracted single-rooted mandibular premolars based on the inclusion and exclusion criteria were used for this study. Access cavity preparation was done for all the samples, and the working length of each sample was determined using a size 10-k file. The radiopaque solution (Urografin) was delivered into (Groups A, B, and C) prepared canal of samples at the rate of 1 ml in 30 s with up-and-down motion. Results: The test results showed that Waterpik WP-100 group showed significantly high infiltration index values as compared to passive irrigation and manual irrigation group at P < 0.002 and P = 0.007, respectively. Conclusion: Sonic irrigation using a Waterpik device modified with a NaviTip needle permits better infiltration of the irrigant.

Apical microleakage in root canals with separated rotary instruments obturated with different endodontic sealers.

Aim: The aim of this study was to evaluate apical microleakage in root canals containing broken rotary instruments obturated with cold lateral condensation and thermoplasticized injectable gutta-percha, with different sealers, using glucose penetration leakage study. Materials and Methods: In this in vitro study, 96 extracted human mandibular premolars were decoronated, and the roots were randomly divided into eight groups (n = 12). Root canals were instrumented with #30 4% taper rotary files. The files were scratched 3 mm from the tip by a high-speed handpiece, and they were intentionally broken in the apical third of the canals. The middle and coronal sections of the canals were obturated by cold lateral condensation and thermoplasticized technique, using ZOE, resin, CaOH, and bioceramic sealers. Apical microleakage was measured using the glucose penetration method. Statistical Analysis: Independent Student's t-test and one-way ANOVA followed by Tukey's post hoc analysis were used for statistical analysis. Results: Bioceramic sealer group showed the least apical microleakage and this was then followed by the resin and CaOH groups demonstrating lesser apical microleakage and the highest microleakage was with the ZOE group. Mean apical microleakage scores between lateral and thermoplastic condensation techniques in each group were statistically significant (P < 0.001). Conclusion: Bioceramic sealer demonstrated the least apical leakage, whereas ZOE seal displayed the highest apical leakage.

An in vivo comparative evaluation of antimicrobial efficacy of chitosan, chlorhexidine gluconate gel and their combination as an intracanal medicament against Enterococcus faecalis in failed endodontic cases using real time polymerase chain reaction (qPCR).

AIM: To evaluate the in vivo antibacterial efficacy of 2% chlorhexidine gel (CHX), 2% chitosan (CS) gel and their combination as an intracanal medicament against Enterococcus faecalis during endodontic retreatment procedure, with the use of qPCR. METHOD: A total of 45 single rooted permanent teeth were selected from 28 systemically healthy patients (mean age of 43 years). After complete disinfection and access opening as well as gutta-percha (GP) removal, the first microbiological pretreatment sample (S1) was collected. After completion of instrumentation, a post-instrumentation sample (S2) was taken and the teeth were randomly divided into three experimental groups: 2% CHX gel; 2% CS gel; 2% CHX with CS; Fuji IX glass ionomer cement was used to seal the access; after 7 days, the post medication sample (S3) was collected and E. faecalis was quantified using qPCR. RESULTS: Maximum reduction in bacterial mean CFU (×106) counts was observed between S1 and S2; S2 and S3; S1 and S3 in 2% CHX with chitosan group compared to other groups. Percentage reduction in CFU (×106) counts at different time intervals (S1-S2; S2-S3; S1-S3) was maximum for the 2% CHX with the chitosan group. Comparison of the mean CFU (×106) count within the 2% CHX gel group and the 2% CHX with chitosan group at different time intervals (S1,S2,S3) was found to be highly significant (P = 0.001); whereas in group II, it was significant (P = 0.002). CONCLUSION: 2% CHX with chitosan group showed the highest microbial reduction against E. faecalis during retreatment of failed endodontic cases.

Comparative Evaluation of Efficacy of Platelet-Rich Fibrin and Hank's Balanced Salt Solution as a Storage Medium for Avulsed Teeth: An In Vitro Study.

OBJECTIVE: To compare the efficacy of platelet-rich fibrin (PRF) and Hank's balanced salt solution (HBSS) in the preservation of the periodontal ligament (PDL) cells viability of avulsed teeth. METHODS: A total of 30 non-carious third molars with healthy periodontium, indicated for extraction for orthodontic reasons or chronic pericoronitis, were selected for the study. Samples were divided into four groups: one standard group and one experimental group in addition to two control groups (positive and negative). The positive and negative control group corresponded to immediate and 2-hour dry time respectively. The experimental teeth were bench dried for 40 minutes and then immersed in one of the two storage media: HBSS (standard storage media) and PRF (experimental storage media) for 45 minutes. The teeth in each group were treated with dispase II and collagenase for 30 minutes and later centrifuged for 4 minutes at 1000 rpm. The supernatant was removed with sterile micropipette, the cells were labeled with 0.4% trypan blue, and the number of viable PDL cells was counted with a hemocytometer under a light microscope. One-way Kruskal-Wallis test and Mann-Whitney U test with Boneferroni correction were used for statistical analysis. RESULTS: Results did not demonstrate any statistically significant differences in the viability of PDL cells between the groups with standard and experimental storage media. Group 1 showed a statistically significant difference of mean compared to Groups 2, 3 and 4. When Group 2 was compared with Groups 3 and 4, a P-value>0.05 suggested no statistical significance. CONCLUSION: Within the parameters of this study, HBSS and PRF demonstrated a similar number of viable PDL cells. Hence, PRF could be a used as a good substitute of HBSS as a storage media for avulsed teeth.

An analysis of cyclic fatigue resistance of reciprocating instruments in different canal curvatures after immersion in sodium hypochlorite and autoclaving: An in vitro study.

AIM: The aim of this study is to assess the effect of sodium hypochlorite and sterilization on the cyclic fatigue resistance of two reciprocating nickel-titanium files using a rotary and a reciprocating motor. MATERIALS AND METHODS: Totally, 160 Reciproc and Wave One files were tested. The eighty files of the same brand were assigned into four groups (n = 20). These four groups were further divided into two subgroups, 1a and 1b, 2a and 2b, 3a and 3b, 4a and 4b consisting of ten files in each group. 2.5% NaOCl for 5 min, 2.5% NaOCl for 5 min + 1 cycle of autoclave sterilization, 2.5% NaOCl for 5 min + 5 cycles of autoclave sterilization, no sterilization (control). Groups 1a, 2a, 3a, and 4a were subjected to 30° and Groups 1b, 2b, 3b, and 4b were subjected to 60° canal curvature. RESULTS: Intergroup comparison reveals that there is an increase in cyclic fatigue resistance from the first cycle to the fifth cycle of autoclave which is statistically significant. CONCLUSION: Reciproc and Wave One showed reduced cyclic fatigue resistance on immersion in NaOCl for 5 min. Multiple autoclaving cycles significantly increased the cyclic fatigue resistance of Reciproc file system in both the curvatures. There was a decrease in cyclic fatigue resistance for Wave One after multiple autoclaving at 60° curvature which was statistically significant.

Scanning electron microscopic evaluation of the influence of manual and mechanical glide path on the surface of nickel-titanium rotary instruments in moderately curved root canals: An in-vivo study.

AIM: The aim of this study was to evaluate the influence of manual versus mechanical glide path (GP) on the surface changes of two different nickel-titanium rotary instruments used during root canal therapy in a moderately curved root canal. MATERIALS AND METHODS: Sixty systemically healthy controls were selected for the study. Controls were divided randomly into four groups: Group 1: Manual GP followed by RaCe rotary instruments, Group 2: Manual GP followed by HyFlex rotary instruments, Group 3: Mechanical GP followed by RaCe rotary instruments, Group 4: Mechanical GP followed by HyFlex rotary instruments. After access opening, GP was prepared and rotary instruments were used according to manufacturer's instructions. All instruments were evaluated for defects under standard error mean before their use and after a single use. The scorings for the files were given at apical and middle third. STATISTICAL ANALYSIS USED: Chi-squared test was used. RESULTS: The results showed that there is no statistical difference between any of the groups. Irrespective of the GP and rotary files used, more defects were present in the apical third when compared to middle third of the rotary instrument. CONCLUSION: Within the limitations of this study, it can be concluded that there was no effect of manual or mechanical GP on surface defects of subsequent rotary file system used.

Effect of dentin on the antimicrobial efficacy of 3% sodium hypochlorite, 2% chlorhexidine, 17% ethylenediaminetetraacetic acid, and 18% etidronic acid on Candida albicans: An in vitro study.

AIM: The aim of this study was to evaluate the effect of dentin on the antimicrobial efficacy of 3% sodium hypochlorite, 2% chlorhexidine, 17% EDTA and 18% etidronic acid against C. albicans. METHODOLOGY: Dentin powder was prepared from mandibular first premolar using electrical grinder and sterilized. 3% NaOCl, 2%CHX, 17% EDTA and 18% etidronic acid were tested against C. albicans in the presence and absence of dentin, in eppendorf tubes. Group 1 (presence of dentin):- 100ul dentin powder + 100ul C. albicans suspension + 100ul irrigating solution. Group 2 (absence of dentin):- 100ul C. albicans suspension+ 100ul irrigating solution. CONTROL GROUP: - 100ul C. albicans suspension.+ 100ul sterile saline Suspension was thoroughly mixed, submitted for serial dilution upto10-5 after 1 min and colony forming units were counted. RESULTS: In group 2 (without dentin powder), 3% NaOCl and 2% CHX showed the lowest bacterial count compared to group 1 (with dentin powder). Dentin had a significant inhibitory effect on 3% NaOCl (P < 0.001) and 2% CHX (P<0.001). 17% EDTA showed lowest bacterial count in group 1 (with dentin powder) compared to group 2 (without dentin powder). 18% Etidronic acid showed similar bacterial counts in the both the groups. No reduction was observed in the control group. CONCLUSION: NaOCl & EDTA showed measurable antimicrobial effect even in the presence of dentin which can be promising in the reduction of C. albicans in root canal therapy.

A comparative analysis of restorative materials used in abfraction lesions in tooth with and without occlusal restoration: Three-dimensional finite element analysis.

OBJECTIVES: The present comparative analysis aimed at evaluating the mechanical behavior of various restorative materials in abfraction lesion in the presence and absence of occlusal restoration. MATERIALS AND METHODS: A three-dimensional finite-element analysis was performed. Six experimental models of mandibular first premolar were generated and divided into two groups (groups A and B) of three each. All the groups had cervical abfraction lesion restored with materials and in addition group A had class I occlusal restoration. A load of 90 N, 200 N, and 400 N were applied at 45° loading angle on the buccal inclines of buccal cusp and Von Mises stresses was chosen for analysis. RESULTS: In all the models, the values of stress recorded at the cervical margin of the restorations were at their maxima. Irrespective of the occlusal restoration, all the materials performed well at 90 N and 200 N. At 400 N, only low-shrink composite showed stresses lesser than its tensile strength indicating its success even at higher load. CONCLUSION: Irrespective of occlusal restoration, restorative materials with low modulus of elasticity are successful in abfraction lesions at moderate tensile stresses; whereas materials with higher modulus of elasticity and mechanical properties can support higher loads and resist wear. SIGNIFICANCE: The model allows comparison of different restorative materials for restoration of abfraction lesions in the presence and absence of occlusal restoration. The model can be used to validate more sophisticated computational models as well as to conduct various optimization studies.

An in vitro evaluation of passive ultrasonic agitation of different irrigants on smear layer removal after post space preparation: a scanning electron microscopic study.

This study evaluated the removal of debris and smear layer after post space preparation using different irrigations and passive ultrasonic agitation. Sixty human premolars were decoronated and post space prepared after endodontic therapy. The samples were then randomly divided into three experimental groups (Groups A, B, C) and one control group (Group D) with fifteen samples in each group. Groups A and B samples were treated with 10 % citric acid and 17 % ethylenediamintetraacetic acid (EDTA), respectively and passive ultrasonic agitation was done, rinsed with sodium hypochlorite and finally flushed with saline. Group C samples were conditioned with 36 % phosphoric acid and then rinsed with saline. The control group was treated with 3 % sodium hypochlorite, passive ultrasonic agitation done and flushed with saline. The samples were sectioned and evaluated for debris and smear layer removal under scanning electron microscope. 10 % citric acid showed the best removal of smear layer when compared with 17 % EDTA and 36 % phosphoric acid, but was not statistically significant (p > 0.05). The difference in scoring for debris and smear layer removal in the coronal, middle and apical third of post space of experimental groups in comparison with control group was statistically significant (p < 0.001).

The reinforcement effect of polyethylene fibre and composite impregnated glass fibre on fracture resistance of endodontically treated teeth: An in vitro study.

AIM: The aim of this study was to evaluate the fracture resistance of endodontically treated maxillary premolars with wide mesio-occluso-distal (MOD) cavities restored with either composite resin, or composite resin reinforced with different types of fibres. MATERIALS AND METHODS: Fifty human maxillary premolars were selected. Five intact teeth served as positive controls. Endodontic therapy was carried out in the remaining forty-five teeth. Standardized MOD cavities were prepared in all the teeth. The teeth were restored with a nanocomposite using an incremental technique. These forty five teeth were randomly divided into three experimental groups (Group A, B and C) (n = 15). The teeth in Group A did not undergo any further procedures. The teeth in Group B and C were reinforced with composite impregnated glass fibre and polyethylene fibre, respectively. Fracture resistance was measured in Newtons (N). RESULTS: The positive controls showed the highest mean fracture resistance (811.90 N), followed by Group B (600.49N), Group A (516.96N) and Group C (514.64N), respectively. One Way analysis of variance (ANOVA) test revealed a statistically significant difference between all the groups (P = 0.001). Post-hoc Tukey test revealed a moderately significant difference (P = 0.034) between Control and Group B, and a strongly significant difference between Control and Group A (P = 0.002), and Control and Group C (P = 0.001). CONCLUSIONS: Endodontic therapy and MOD cavity preparation significantly reduced the fracture resistance of endodontically treated maxillary premolars (P = 0.001). No statistically significant difference was found between the experimental groups (Group A, B and C) (P > 0.1). However, the fracture resistance of the composite impregnated glass fibre reinforced group was much higher than the others.

Infinite to finite: an overview of finite element analysis.

The method of finite elements was developed at perfectly right times; growing computer capacities, growing human skills and industry demands for ever faster and cost effective product development providing unlimited possibilities for the researching community. This paper reviews the basic concept, current status, advances, advantages, limitations and applications of finite element method (FEM) in restorative dentistry and endodontics. Finite element method is able to reveal the otherwise inaccessible stress distribution within the tooth-restoration complex and it has proven to be a useful tool in the thinking process for the understanding of tooth biomechanics and the biomimetic approach in restorative dentistry. Further improvement of the non-linear FEM solutions should be encouraged to widen the range of applications in dental and oral health science.