Sealing ability of retrofilling materials following various root-end cavity preparation techniques

Comparison of fracture resistance of simulated immature teeth using four different commercially available apexification materials - An in vitro study

Introduction

The aim of this study was to compare the fracture resistance of simulated immature teeth using four different apical plug materials, i.e. Pro- Root MTA, Neo- MTA Plus, Biodentine, and Bioactive Glass.

Materials and Methods

80 extracted human maxillary anterior teeth were divided into 4 groups for this study. They were prepared using Peeso reamers to simulate immature teeth and to mimic Cvek's stage 3 of root development. A 5 mm apical barrier was placed using different materials. The remaining canal was obturated using gutta-percha and AH plus sealer. The final samples were stored at 37°C and 100% humidity for 4 weeks. Fracture resistance of the teeth was measured in Newtons using a universal testing machine. The comparison of fracture resistance between the four groups was done using Kruskal Walis ANOVA followed by post hoc Mann Whitney U test for pairwise comparison.

Results

Biodentine group showed the highest fracture resistance as compared to the other three groups and the difference was highly significant (P < 0.001).

Conclusions

Biodentine can be advocated over MTA as an effective material for the management of teeth with wide open apex. Bioactive glass also has shown promising results in increasing the fracture resistance of simulated immature teeth.

Sealing Ability of Bioactive Root-End Filling Materials in Retro Cavities Prepared with Er,Cr:YSGG Laser and Ultrasonic Techniques

The aim of this in vitro study was to compare the apical sealing ability of total fill bioceramic root repair material (BC-RRM) and mineral trioxide aggregate (MTA), regarding the retrograde preparation technique used: ultrasonic or erbium, chromium: yttrium, scandium, gallium, or garnet (Er,Cr:YSGG) laser. The study sample consisted of 48 human single-rooted teeth. After root-end resection, the samples were divided into two groups, according to the retrograde preparation technique used: Group 1: ultrasonic; Group 2: Er,Cr:YSGG laser. In each group, half of the retrograde cavities were filled with BC-RRM, and the other half were filled with MTA. The specimens were mounted in tubes and sterilized in plasma. The root canals were inoculated with Enterococcus faecalis, and the tubes were filled with fetal bovine serum, leaving the apical part of the root in the serum. After 30 days, the canals were sampled and cultured, and the colony forming units (CFUs) were counted with the additional polymerase chain reaction (PCR analysis). There was no significant difference between ultrasonic groups and the Er,Cr:YSGG-MTA group, regarding the number of CFUs (p > 0.05). The Er,Cr:YSGG-BC-RRM group showed the highest number of remaining viable bacteria (p < 0.001). Both filling materials filled in ultrasonic preparations presented similar sealing abilities. The BC-RRM showed more leakage when used in retro cavities prepared with the Er,Cr:YSGG laser.

The Effect of Root End Cavity Preparation Using Er,Cr:YSGG Laser, Ultrasonic Retrotip, and Bur on the Apical Microleakage of Retrograde Cavity Filled with MTA Plus

Aim:

The sealing ability of the retrograde material is greatly affected by the technique used for root end preparation. Advances in retrograde preparation techniques such as lasers has shown to provide an efficient outcome. The study was to evaluate and compare the effect of various techniques of retrograde cavity preparation on apical microleakage.

Materials and Methods:

Forty-five single rooted teeth were decoronated. Biomechanical preparation was carried out up to size F2 ProTaper system and obturated. Glass–ionomer cement was used as an access restorative material. The apical root resection was done at 3 mm from the apex at angulation of 90° to the long axis of the root. The allocation of the samples was done into three groups of 15 each. Group A: Retrograde cavities prepared using conventional round bur; Group B: Retrograde cavities prepared using ultrasonic retro preparation diamond tip; and Group C: Retrograde cavities prepared using “Erbium, chromium: yttrium, scandium, gallium, garnet” (Er,Cr:YSGG). The retrograde cavities hence prepared were filled with MTA Plus. Nail varnish was used to coat the samples except at the apical end. Samples were immersed in methylene blue for 24h. Stereomicroscope was used for examination of the sectioned teeth. The data were analyzed using one-way analysis of variance (ANOVA) and post hoc Tukey test.

Results:

Results showed very highly significant difference between laser and bur (P value = 0.001).

Conclusion:

Retrograde preparation with Er,Cr:YSGG showed significantly less microleakage when compared to the use of ultrasonic retrotip and burs.

Effect of Mineral Trioxide Aggregate Apical Plug Thickness on Fracture Resistance of Immature Teeth

INTRODUCTION

The aim of this study was to compare the fracture resistance of simulated immature teeth after using different thicknesses of mineral trioxide aggregate (MTA) apical plugs.

METHODS

Fifty-two human maxillary anterior teeth were used. Five teeth were the positive control group; they were prepared using Peeso reamers to simulate immature teeth without any access cavity preparation. Access cavities of the 47 teeth were prepared, and the canals were instrumented with Peeso reamers. Five teeth served as the negative control; they were filled with calcium hydroxide. Forty-two teeth were divided into 3 groups; in groups 1, 2, and 3, MTA was placed into canals as a 3-mm and a 6-mm apical plug and a thorough canal length, respectively. The rest of the canals in groups 1 and 2 were filled with gutta-percha and AH Plus sealer (Dentsply DeTrey, Konstanz, Germany). After the storage period, the roots were covered with a polyether impression material and were embedded into self-curing resin blocks. Each specimen was then subjected to fracture testing using a universal testing machine. Data were analyzed using 1-way analysis of variance with the Tukey post hoc test for multiple comparisons.

RESULTS

The negative group showed the lowest fracture resistance compared with the other groups. The 3-mm apical plug group showed the highest fracture resistance (P < .05). No significant differences were found between the 3-mm and 6-mm apical plug groups (P > .05).

CONCLUSIONS

MTA should be used as an apical plug instead of root canal filling material to increase the fracture resistance of immature teeth.

Effect of Er,Cr:YSGG laser irradiation on apical sealing ability of calcium silicatecontaining endodontic materials in root-end cavities

The aim of this research was to evaluate the apical sealing abilities of 60 root-end cavities filled with mineral trioxide aggregate (MTA) and iRoot BP cements after treated with either 17% EDTA solution or Er,Cr:YSGG laser irradiation. After the filling procedure, apical leakage quantity was measured at 4 weeks using a fluid filtration method. One root from each group was processed for scanning electron microscopy and energy dispersive X-ray spectroscopy analyses. Both EDTA/MTA and laser irradiation/MTA combinations showed significantly lower microleakage than EDTA/iRoot BP and laser irradiation/iRoot BP combinations (p<0.05). Between groups of the same filling material, there were no significant differences among specimens treated with EDTA or laser (p>0.05). Both MTA and iRoot-BP demonstrated tag-like structures within the dentinal tubules when used in conjunction with EDTA.

Sealing ability of mineral trioxide aggregate (MTA) combined with distilled water, chlorhexidine, and doxycycline

The aim of this study was to evaluate the sealing ability of mineral trioxide aggregate (MTA Bio) combined with different mixing agents (distilled water, chlorhexidine, doxycycline), used as an apical root-end filling material. Forty-two extracted human teeth were divided into three groups (n = 12); six teeth were used as controls. Root-ends were resected at 90 degrees, 3 mm from the apex. Root-end cavities were prepared using ultrasonic tips and filled with MTA Bio plus distilled water, 2% chlorhexidine solution, or 10% doxycycline solution. Apical sealing was assessed by microleakage of 50% silver nitrate solution. Roots were longitudinally sectioned in a buccolingual plane and analyzed using an operating microscope (20× magnification). Depth of dye leakage into the dentinal walls was measured in millimeters. Results were analyzed using ANOVA and Tukey's test (P = 0.05). MTA Bio plus distilled water showed significantly higher mean leakage results (1.06 mm) when compared with MTA Bio plus doxycycline (0.61 mm), and higher, although not significant, results when compared with MTA Bio plus chlorhexidine (0.79 mm). In conclusion, replacing distilled water with two biologically active mixing agents (doxycycline and chlorhexidine) did not alter the sealing properties of MTABio. The antimicrobial properties of these combinations should be further investigated.

Effect of Nd: YAG laser on the apical seal after root-end resection and MTA retrofill: a bacterial leakage study

Laser irradiation has been investigated in terms of preventing leakage in retrofilled root canals. The aim of the present study was to evaluate the effect of neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on the bacterial leakage of mineral trioxide aggregate (MTA)-retrofilled roots. In this ex vivo experimental study, 90 single-rooted incisor teeth were filled with gutta-percha and AH26 sealer. The apical 3 mm of all the roots were resected and 3-mm retrocavities were prepared by an ultrasonic device. The specimens were randomly divided into two experimental (n = 25), one positive control (n = 10), and two negative control (n = 10) groups. In the laser + MTA group, the cavity walls were irradiated by Nd: YAG laser prior to MTA placement. In the MTA group, MTA was placed without laser irradiation. The root surfaces were covered with two layers of nail varnish except for the apical 2 mm. The specimens were then embedded in a bacterial leakage test system and examined daily for 90 days. Contamination periods were recorded. Data were analyzed by Kaplan-Meier and Mann-Whitney U tests (α = 0.05). Five teeth with and five teeth without laser irradiation underwent scanning electron microscopic evaluation. The specimens in the laser + MTA group were contaminated earlier than those in the MTA group (p < 0.05). Comparison of survival times between the two groups showed significant differences (p < 0.05). Nd: YAG laser irradiation can decrease the sealing capacity of MTA in comparison to the apical seal achieved by MTA without laser irradiation. Further studies are recommended to provide a better seal for the MTA-retrofilled teeth after laser irradiation.