Percentage of Gutta-percha–filled Areas in Canals Obturated by 3 Different Techniques with and without the Use of Endodontic Sealer

Performance of obturation techniques in anatomical irregularities located at different thirds of the root canal system

This study aimed to compare the quality of root canal obturation (ratio of area occupied by gutta-percha (G), sealer (S), and presence of voids (V)) in different anatomical irregularities (intercanal communications, lateral irregularities, and accessory canals) located at different thirds of the root canal system of mandibular molar replicas. Sixty-seven 3D printed replicas of an accessed mandibular molar were prepared using ProGlider and ProTaper Gold rotatory systems. Three specimens were randomly selected to be used as controls and did not receive further treatment. The rest were randomly distributed in 4 experimental groups to be obturated using either cold lateral compaction (LC), continuous wave of condensation (CW), and core-carrier obturation (ThermafilPlus (TH) or GuttaCore (GC)) (n=16 per group). AHPlus® sealer was used in all groups. The three controls and a specimen from each experimental group were scanned using micro-computed tomography. The rest of the replicas were sectioned at the sites of anatomical irregularities and examined at 30× magnification. The G, S, and V ratios were calculated dividing the area occupied with each element by the total root canal area and then compared among groups using the Kruskal-Wallis test. Voids were present in all obturation techniques with ratios from 0.01 to 0.15. CW obtained a significantly higher G ratio in the irregularity located in the coronal third (0.882) than LC (0.681), TH (0.773), and GC (0.801) (p<0.05). TH and GC achieved significantly higher G ratios in those located in the apical third (p<0.05). The worst quality of obturation was observed in the loop accessory canal with all obturation techniques. Whitin the limitations of this study, it can be concluded that CW and core-carrier obturation are respectively the most effective techniques for obturating anatomical irregularities located in the coronal and the apical third.

Biological considerations of dental materials as orifice barriers for restoring root-filled teeth

There is ample published literature regarding the technical aspects of restoring root-filled teeth, but little concerning the biological impacts, consequences, and criteria for the selection of direct restorative materials following endodontic treatment. The provision of an effective coronal seal in addition to a sound root filling is known to be important in the prevention of root canal infection. This review seeks to explore the evidence concerning the selection of dental materials in the restoration of root-filled teeth, specifically with a close examination of the properties of commonly used materials as orifice barriers. © 2023 Australian Dental Association.

New Ultrasonic Tip for Root Canal Filling of the Mesial Canals of Mandibular Molars with Isthmus: A Laboratory Evaluation Using Computed Microtomography

INTRODUCTION

The obturation quality of the mandibular molar mesial canals and isthmuses with two thermoplastic techniques, ultrasonic vertical condensation (UVC) and continuous wave of condensation (CWC), was evaluated using computed microtomography (μCT).

METHODS

Thirty-six human mandibular molars had been previously scanned and analyzed using μCT for mesial roots with morphologically similar isthmuses for this study. Coronal access and confirmation of foraminal patency were performed, and the actual length of the teeth was established using a clinical microscope (40X magnification). The canals were prepared using ProTaper Gold instruments up to #F3, with 2.5% sodium hypochlorite as the irrigant solution, followed by a passive ultrasonic irrigation protocol. The specimens were randomly divided into the UVC and CWC groups based on the obturation technique to be used. Obturation was performed with #F3 gutta-percha cones cemented using AH Plus Jet sealer. The μCT scans were performed after 15 days, and the images were evaluated by a calibrated examiner blinded to the experimental groups to determine the filling rate of the entire canal area, including the main canal and isthmus. Student's t-test was used for statistical analysis; P values ≤0.05 were considered significant.

RESULTS

Neither of the thermoplastic obturation techniques achieved complete filling of the canals (86.3% for UVC and 91.4% for CWC), with a statistically significant difference between them (P = .029).

CONCLUSIONS

Under the conditions of the study, it can be concluded that none of the techniques completely filled the canal/isthmus of the mandibular molars; however, the CWC exhibited better performance.

A micro-computed tomographic analysis of obturation quality and retreatability of an epoxy resin-based sealer

BACKGROUND

To evaluate the voids percentage and the retreatability by different supplementary irrigation techniques of a matched-taper single cone and epoxy resin-based sealer.

METHODS

A total of 72 single-rooted premolars were prepared and filled with gutta-percha and MM-Seal. The percentage of voids in the whole root canal and each anatomical part were evaluated by Micro-CT scans. After root filling removal, the teeth were randomly allocated (n=24) to group A, syringe irrigation; group B, Tornado Brush and group C, ultrasonically activated irrigation and rescanned to establish the volume of remnant root filling material. The data relative to voids and retreatment techniques were established by Kruskal-Wallis test. Differences in retreatment time were examined using one-way ANOVA and Tukey's test (P< .05).

RESULTS

No significant difference was found in the voids percentage between the different root-thirds and between the supplementary irrigation groups in the MM-Seal remnants for the whole root canal and each section. In all groups, the coronal region exhibited more remaining material than other sections.

CONCLUSIONS

MM-Seal showed low voids percentage and its removal was not significantly improved by supplementary irrigation techniques.

Randomised controlled trial of a microneedle patch with a topical anaesthetic for relieving the pain of dental injections

OBJECTIVES

To determine whether a microneedle patch combined with 5% topical lidocaine reduces dental injection pain more than a patch without microneedles combined with 5% topical lidocaine.

METHODS

This proof of principle randomised, two-treatment, double-blind, crossover split-unit design study in 16 healthy participants investigated levels of perceived pain from 3 increasing pain provoking challenges, when topical 5% lidocaine dental gel was applied to the oral mucosa with a microneedle patch and a patch with no microneedles, prior to infiltration with local anaesthesia on 2 visits. Pain was assessed by visual analogue scale (VAS) and 4-point verbal rating scale (VRS).

RESULTS

15 participants completed the study. Mean pain scores, lower at buccal sites, increased in both groups across challenges 1-3: Test palatal 5.1, 11.9, 26.8; buccal 0.7, 2.8, 18.3; Control palatal 12.3, 18.7, 39.5; buccal 4.0, 6.9, 30.6. The microneedle patch plus lidocaine significantly lowered VAS pain scores at both sites for all challenges, the biggest mean difference seen palatally after challenge 3 (12.7, p < 0.001). VRS pain scores were also significantly reduced for test compared to control for all 3 challenges (p = 0.014). Buccal scores favoured the microneedle patch, significantly for pain challenge 3 (p = 0.025). No adverse events occurred.

CONCLUSIONS

Prior oral application of a microneedle patch combined with 5% topical lidocaine gel reduced the pain experienced from dental infiltration. Microneedle patch use in the dental setting offers the prospect of improving degree and depth of anaesthesia from topically applied anaesthetic gel, without itself causing any pain.

CLINICAL SIGNIFICANCE

Dental injections are associated with fear and anxiety. Application of a microneedle patch, combined with topical anaesthetic, to the oral mucosa prior to delivery of the injection reduces the pain from this dental procedure. This novel technique may allay patients' apprehension of local anaesthesia and improve quality of life outcomes.

Correlation among Root Canal Configuration, Quality of Filling, and Its Sealability

Objective  This study aimed to evaluate the existence of possible correlations among root canal configuration, quality of filling, and its sealability.

Materials and Methods  Sixty human mandibular central incisors were selected for this study. The teeth were prepared with the Profile 04 system up to instrument 35/0.04 and irrigated with 2.5 mL of 2.5% sodium hypochlorite at each instrument change. Root canal filling was performed by the lateral compaction technique, using gutta-percha and an epoxy resin-based sealer (AH Plus) labeled with 0.1% Rhodamine B dye. Afterward, the specimens were submitted to fluid filtration tests to assess the sealability of the filling. Cross-sections were obtained at −3, −6, and −8 mm from the root apex and submitted to a metallographic treatment to determine the root canal configuration and the percentage of gutta-percha filled areas. The data were statistically analyzed by the Grubbs test. Pairs of correlations were analyzed by applying the Spearman test at a level of significance of 5%.

Results  No correlation was observed among the analyzed variables as follows: root canal configuration versus filling quality (Spearman’s rho = 0.031); filling quality versus sealability (Spearman’s rho = 0.219); and root canal configuration versus sealability (Spearman’s rho = 0.184).

Conclusion  The root canal configuration did not affect the quality of the filling and its sealability.

Percentage of Gutta-Percha-, Sealer-, and Void-Filled Areas in Oval-Shaped Root Canals Obturated with Different Filling Techniques: A Confocal Laser Scanning Microscopy Study

Objective  This study compared different obturation techniques, analyzing percentage of areas filled with gutta-percha, sealer, and voids (PGFA, PSFA, and PVFA, respectively) in oval-shaped root canals.

Materials and Methods  A total of 60 extracted human mandibular central incisors were decoronated, instrumented, and irrigated using the same protocol. After drying, the root canal was filled with AH Plus labeled with 0.1% rhodamine B dye using a Lentulo spiral. The filling procedure was performed by dividing the teeth into four groups according to the respective technique: G1, cold lateral condensation; G2, continuous wave of condensation; G3, modified cold lateral condensation using an F3 master cone; and G4, modified continuous wave of condensation using an ISO (International Organization for Standardization) sized 30 gutta-percha cone. Then, slices measuring 1.5 mm in thickness were obtained 3 and 6 mm from the apex and evaluated by confocal laser scanning microscopy to determine PGFA, PSFA, and PVFA.

Statistical Analysis  The data were analyzed statistically with analysis of variance and Games-Howell’s tests ( p = 0.05).

Results  The groups showed no significant differences in the apical third (3 mm from the apex). In the middle third (6 mm from the apex), G3 and G1 showed higher PGFA and PVFA, respectively. G3 showed lower PSFA than G2 and G4. Both cold techniques (G1 and G3) promoted lower PSFA than both warm techniques (G2 and G4).

Conclusions  Notwithstanding the limitations of this in vitro study, PGFA, PSFA, and PVFA ranged significantly only in the middle third, as observed by the different filling techniques. Higher PGFA and PVFA values were obtained for G3 and G1, respectively. Both cold techniques promoted lower PSFA than both warm techniques.

CAD/CAM Customized Glass Fiber Post and Core With Digital Intraoral Impression: A Case Report

Background

After endodontic treatment, a proper restorative technique is necessary to ensure coronal seal and protection of residual dental structure; teeth which have lost two or more walls need to be restored with posts to increase retention and stability of final restoration. Posts can be distinguished in prefabricated and customized, which are manufactured by lost wax technique or CAD-CAM.

Purpose

Digital dentistry has been developed to increase workflow precision and to accelerate production process; use of CAD-CAM to realize customized posts was limited to scanning plaster models obtained from traditional impressions.

Patients and Methods

In the reported case an intraoral scan was used to mill a post and core restoration on an endodontically treated inferior premolar; this operative protocol was based on previous in vitro experiments that confirmed the ability of 3shape Trios scanner to read post-space up to 9 mm in depth.

Results

The digital technique allows us to convert the concave surface of the root canal into the convex surface of the post, and realize an anatomical post and core that improves the biomechanics of the endodontically treated tooth reducing the possibility of root fractures.

Conclusion

The use of an intraoral digital scanner represents an opportunity for the clinician as it speeds up the production of an anatomical post and core restorations.

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