Homogeneity and adaptation of endodontic fillings in root canals with enlarged apical preparation

Influence of Apical Preparation Size on Effective Conventional Irrigation in the Apical Third: A Scanning Electron Microscopic Study

Objective

This study aimed to investigate the relationship between final apical preparation size and smear layer removal in the apical third using conventional irrigation in mandibular bicuspids.

Methods

A total of 66 extracted human mandibular bicuspids with comparable root canal morphology were equally divided into five experimental groups and a control group (n=11). Based on their experimental group, samples were instrumented up to size 25, 30, 35, 40, or 45 with 0.04 taper using 2.5% sodium hypochlorite (NaOCl) as the irrigant. Final irrigation was performed with 17% EDTA followed by 2.5% NaOCl. The control group was instrumented up to size 45/.04, and was irrigated with distilled water. Samples were sectioned buc-colingually, and they were qualitatively evaluated under scanning electron microscope for efficacy in smear layer removal. The Kruskal-Wallis and Mann-Whitney U tests were employed for statistical analysis.

Results

Statistical analysis revealed comparable removal of smear layer in the coronal and middle thirds of all experimental samples regardless of grouping. When using file size larger than 35, removal of smear layer in the apical third significantly improved (p<0.05). No significant difference was observed between 40/.04 and 45/.04.

Conclusion

Under the conditions of this study, using conventional irrigation, apical enlargement more than size 35/.04 is essential to enhance removal of smear layer at the apical third.

Relationship between the Apical Preparation Diameter and the Apical Seal: An In Vitro Study

Objectives

The aim of the study is to define the relationship between the apical preparation diameter and the apical sealing ability to highlight the importance of the preservation of the diameter and the original position of the apical foramen.

Materials and Methods

50 extracted maxillary incisors were randomly allocated into three groups of 15 teeth each (n = 15) according to the apical preparation size: Group 1: finishing file F1 corresponding to size 20 reached the working length (ProTaper Universal system Dentsply®); Group 2: prepared up to size 30 corresponding to finishing file F30; Group 3: prepared up to size 50 corresponding to finishing file F5. Five teeth were assigned to positive and negative control groups. After the filling of the root canals, the teeth were isolated and immersed in a dye solution, then cut longitudinally, photographed, and the dye penetration were calculated using a computer software.

Results

Comparison of the three different apical preparation sizes showed no statistically significant differences regarding the apical microleakage.

Conclusion

The most important value of the dye penetration was observed in the group with the largest apical diameter.

Influence of NiTi alloy on the root canal shaping capabilities of the ProTaper Universal and ProTaper Gold rotary instrument systems

Objective

This study aimed to evaluate the influence of the NiTi wire in Conventional NiTi (ProTaper Universal PTU) and Controlled Memory NiTi (ProTaper Gold PTG) instrument systems on the quality of root canal preparation.

Material and Methods

Twelve mandibular molars with separate mesial canals were scanned using a high-definition microcomputed tomography system. The PTU and PTG instruments were used to shape twelve mesial canals each. The canals were scanned after preparation with F2 and F3 instruments of the PTU and PTG systems. The analyzed parameters included the remaining dentin thickness at the apical and cervical levels, root canal volume and untouched canal walls. Data was analyzed for statistical significance by the Friedman and Dunn's tests. For the comparison of data between groups, the Mann-Whitney test was used.

Results

In the pre-operative analysis, there were no statistically significant differences between the groups in terms of the area and volume of root canals (P>.05). There was also no statistically significant difference between the systems with respect to root canal volume after use of the F2 and F3 instruments. There was no statistical difference in the dentin thickness at the first apical level between, before and after instrumentation for both systems. At the 3 cervical levels, the PTG maintained centralization of the preparation on the transition between the F2 and F3 instruments, which did not occur with the PTU. Conclusion The Conventional NiTi (PTU) and Controlled Memory NiTi (PTG) instruments displayed comparable capabilities for shaping the straight mesial root canals of mandibular molars, although the PTG was better than the PTU at maintaining the centralization of the shape in the cervical portion.

Theoretical distribution of gutta-percha within root canals filled using cold lateral compaction based on numeric calculus

This study aimed to present a new method based on numeric calculus to provide data on the theoretical volume ratio of voids when using the cold lateral compaction technique in canals with various diameters and tapers. Twenty-one simulated mathematical root canal models were created with different tapers and sizes of apical diameter, and were filled with defined sizes of standardized accessory gutta-percha cones. The areas of each master and accessory gutta-percha cone as well as the depth of their insertion into the canals were determined mathematically in Microsoft Excel. When the first accessory gutta-percha cone had been positioned, the residual area of void was measured. The areas of the residual voids were then measured repeatedly upon insertion of additional accessary cones until no more could be inserted in the canal. The volume ratio of voids was calculated through measurement of the volume of the root canal and mass of gutta-percha cones. The theoretical volume ratio of voids was influenced by the taper of canal, the size of apical preparation and the size of accessory gutta-percha cones. Greater apical preparation size and larger taper together with the use of smaller accessory cones reduced the volume ratio of voids in the apical third. The mathematical model provided a precise method to determine the theoretical volume ratio of voids in root-filled canals when using cold lateral compaction.

Apical filling characteristics of carrier-based techniques vs. single cone technique in curved root canals

OBJECTIVES

In this in vitro study, we assessed filling characteristics (adaptation, homogeneity, sealer percentage, position of the carrier) of warm and cold obturation methods in curved root canals.

MATERIALS AND METHODS

A reciprocating method was used to prepare 90 curved roots (25 ° average curvature) to an apical size of 25.08. They were then obturated with either (A) Guttafusion (VDW, Munich, Germany), (B) Thermafil (Maillefer, Ballaigues, Switzerland) or (C) single cone technique using 25.08 gutta-percha (VDW) and sealer (2Seal easymix) (n = 30 each group). Five sections in 1-mm steps were obtained from each root, beginning 1 mm short of the apex. The percentage of voids in contact with root canal walls (PVO), the proportion of voids per area (PVA) and the percentage of sealer per area (PSA) were measured.

RESULTS

Little to no differences between Guttafusion and Thermafil were seen in curved root canals with respect to adaptation and homogeneity in the apical region. Both methods showed significantly better adaptation and homogeneity than the single cone technique. The proportion of sealer was significantly greater when roots were obturated with Guttafusion than with Thermafil, but both warm obturation techniques had significantly smaller sealer areas than the single cone technique.

CONCLUSIONS

Compared to the single cone technique, a more favourable root canal filling with less sealer could be expected from both warm obturation techniques in curved root canals.

CLINICAL RELEVANCE

The easier-to-handle Guttafusion leads to comparable results as Thermafil in curved root canals.

Comparison of apically extruded debris after large apical preparations by full-sequence rotary and single-file reciprocating systems

AIM

To evaluate the amount of apically extruded debris produced by ProTaper Universal (PTU), ProTaper Next (PTN), WaveOne (WO) and Reciproc (R) systems after large apical preparations.

METHODOLOGY

Sixty mandibular premolars with a single canal were selected and randomly assigned into 4 groups (n = 15) according to the system used for root canal preparation: PTU, PTN, WO and R groups. Canal preparations were performed up to size 40 in each group. Distilled water was used as an irrigant, and the apically extruded debris from each tooth was collected in pre-weighted glass vials and dried. The average weight of debris was assessed using a microbalance, and the data were analysed statistically using one-way analysis of variance and the post hoc Tukey multiple comparison test (α = 0.05).

RESULTS

The PTU system was associated with significantly more debris than the other systems (P < 0.05). No significant differences were found between PTN, WO and R systems (P > 0.05).

CONCLUSIONS

All systems were associated with apical debris extrusion when canals were prepared to a large apical size. The PTU system was associated with more debris extrusion.

Comparative analysis of three different filling techniques and the effects of experimental internal resorptive cavities on apical microleakage

Objectives:

The aim of this study was to evaluate the sealing abilities of three different gutta-percha techniques in experimentally defective roots (EDR) and non-defective roots (NR).

Materials and Methods:

Sixty canine teeth were divided into six groups of ten; Group 1, NR + cold lateral condensation (CLC); Group 2, EDR + LC; Group 3, NR + BeeFill; Group 4, EDR + BeeFill; Group 5, NR + Thermafil; and Group 6, EDR + Thermafil. Apical leakage was measured using a computerized fluid filtration meter with a laser system.

Results:

Statistical analysis revealed that the CLC demonstrated more microleakage in the EDR than in the NR (P < 0.01). Thermafil demonstrated more microleakage in the NR than in the EDR (P < 0.01). No statistically significant differences were found between the BeeFill groups (P > 0.05).

Conclusions:

The results of this study indicate that internal resorptive cavities can affect the apical sealing properties of different root canal filling techniques, with Thermafil ensuring the lowest apical microleakage.

Sealing ability of lateral condensation, thermoplasticized gutta-percha and flowable gutta-percha obturation techniques: A comparative in vitro study

Aim:

To evaluate and compare the sealing ability between the clod lateral condensation, thermoplasticized gutta-percha, and flowable gutta-percha obturation technique, under a stereomicroscope at ×40 magnification.

Materials and Methods:

Sixty single rooted teeth were selected and canals were shaped with K3 NiTi files. Irrigation was performed with 5.25% NaOCl and 17% ethylenediaminetetraacetic acid (EDTA). The teeth were then separated into three groups depending on the type of obturation technique: Group A, obturated using the lateral condensation technique and AH Plus sealer; Group B, obturated with thermoplasticized gutta-percha tech (Obtura III Max) and AH Plus sealer; and Group C, obturated using flowable gutta-percha technique (GuttaFlow). After storing the teeth in 100% humidity for 7 days at 37°C, the roots of the teeth were sectioned at five levels. The sections were then observed under a stereomicroscope at ×40 magnification and the images were analyzed for area of voids (AV) and frequency of voids. The data were statistically analyzed using the SPSS version 17 software. The 95% confidence intervals (CI) were calculated. One-way analysis of variance with post hoc test and non-parametric Mann–Whitney U test were carried out to compare the means.

Results:

The lowest mean of AV was recorded in the thermoplasticized gutta-percha (Obtura III Max) group [1.0% (95% CI=0.5–1.5)]. This was statistically and significantly different from flowable gutta-percha (GuttaFlow) group [3.0% (95% CI=2.1–3.9)]. There was no significant difference between the thermoplasticized gutta-percha group and lateral condensation group [1.6% (95% CI=1.0–2.2)] with regard to the AV, but there was a statistically significant difference between the lateral condensation and flowable gutta-percha groups. The flowable gutta-percha group showed the maximum number of voids [56% (95% CI=48–64)], which was significantly higher than those in the lateral condensation [26% (95% CI=19–34)] and thermoplasticized gutta-percha [15% (95% CI=10–21)] groups.

Conclusion:

The thermoplasticized gutta-percha technique (Obtura III Max) had better adaptability to the canal walls when compared to the flowable gutta-percha (GuttaFlow) obturation and lateral condensation techniques.

Interfacial adaptation of an epoxy-resin sealer and a self-etch sealer to root canal dentin using the System B or the single cone technique

The aim of this laboratory study was to compare the interfacial adaptation of an epoxy-resin and a self-etch sealer in mesial root canals of mandibular molars filled using the System-B/Elements Obturation Unit. Sixty mesial root canals of mandibular molars were prepared using the K3 rotary system up to 35.04 instrument and then filled with the aid of the System-B/Elements Obturation Unit using either gutta-percha/ThermaSeal Plus (n=15) or Resilon/Real Seal SE (n=15). The single cone technique using both materials was used as control. The sealers were stained with Rhodamine B dye and the teeth were filled and sectioned at 2, 4 and 6 mm from the apex. The interfacial marginal adaptation of sealers was evaluated using confocal microscopy. Statistical analyses were performed by the Kruskall-Wallis test (α=0.05). In general, microscopic analysis showed a quite regular gap distribution pattern at sealer-dentin interfaces, mainly for the two groups filled with Real Seal SE. This means that both nonbonding root-filling groups (ThermaSeal Plus) showed significantly higher amount of gap-free regions regardless of the filling technique (p<0.05). Better marginal adaptation was obtained with gutta-percha and epoxy resin-based sealer using either the system B or the single cone technique.

Evaluation and comparison of sealing ability of three different obturation techniques - Lateral condensation, Obtura II, and GuttaFlow: An in vitro study

AIM

To evaluate and compare the sealing ability between the conventional cold lateral condensation technique and two different obturating techniques - Obtura II and GuttaFlow under a stereomicroscope at 40× magnification.

MATERIALS AND METHODS

Sixty single-rooted teeth were selected and the canals were shaped with ProTaper rotary files. Irrigation was performed with 5% sodium hypochlorite and 17% EDTA. The teeth were then separated into three groups depending on the type of obturation technique. Group A (n = 20) - obturated using the Lateral condensation technique and AHplus sealer, Group B (n = 20) - obturated with Obtura II injection-molded thermoplasticized technique and AHplus sealer, and Group C (n = 20) obturated using GuttaFlow. After storing the teeth in 100% humidity for seven days at 37°C, the roots of the teeth were sectioned at five levels. The sections were then observed under a stereomicroscope at 40 × magnification and the images were analyzed for area of voids (AV) and frequency of voids.

STATISTICAL ANALYSIS USED

The data was statistically analyzed using the SPSS version 17 software. The 95% confidence intervals (CI) were calculated. One-way analysis of variance with post-hoc test and non-parametric Mann-Whitney U test was carried out, to compare the means.

RESULTS

The lowest mean of AV was recorded in the Obtura II group, 1.0% (95% CI = 0.5 - 1.5). This was statistically and significantly different from the GuttaFlow group, 3.0% (95% CI = 2.1 - 3.9). There was no significant difference between the Obtura II group and the lateral condensation group, 1.6% (95% CI= 1.0 - 2.2) with regard to the area of voids, but there was a statistically significant difference between the Lateral condensation and GuttaFlow groups. The GuttaFlow group showed the maximum number of voids, 56% (95% CI = 48 - 64), which was significantly higher than those in the lateral condensation, 26% (95% CI= 19 - 34), and Obtura II, 15% (95% CI= 10 - 21) groups.

CONCLUSION

The Obtura II technique utilizing the injection-molded thermoplasticized gutta-percha had better adaptability to the canal walls when compared to the GuttaFlow obturation and lateral condensation techniques.

[Microleakage of root canal fillings with GuttaFlow and Resilon compared with lateral condensation]

Epiphany/Resilon and GuttaFlow are newly developed methods for obturation of the root canal system. Epiphany/Resilon is a thermoplastic, synthetic polymer-based root canal filling material which enables the bonding to the dentin root canal wall during root canal obturation. GuttaFlow is a cold flowable filling system for the obturation of root canals, combining sealer and gutta-percha in one product. The purpose of this study was to assess the leakage of the Epiphany/Resilon or GuttaFlow root canal filling compared with lateral condensation of gutta-percha. For this study were used 45 human extracted teeth, chemo mechanically prepared, divided into three groups and obturated with gutta-percha/AH Plus, Epiphany/Resilon and GuttaFlow. For dye penetration all teeth were centrifuged for three minutes at 30 g in 2% methylene blue and dissolved in 65% nitric acid for 3 days. The extracted methylene blue was determined with Photometer. Root Canal fillings with Epiphany/Resilon showed less dye penetration than lateral condensation of gutta-percha and GuttaFlow. Epiphany/Resilon is ideally suited as a root canal filling material.

Evaluation of single root canals filled using the lateral compaction, tagger's hybrid, microseal and guttaflow techniques

The aim of this study was to determine the percentage of voids, gutta-percha and root canal sealer using 4 different filling techniques. Fifty-two extracted maxillary lateral incisors were prepared using the crown-down pressureless technique. The teeth were randomly divided in 4 groups (n=13): Lateral compaction (LC), Tagger's hybrid (TH), MicroSeal (MS) and GuttaFlow (GF) techniques. Horizontal cross-sections were made at the 2, 10 and 15 mm levels from the apex. Digital images of the root canal areas were acquired using a stereomicroscope and examined using the Image Tool 3.0 software. Statistical analysis was performed using the Kruskal-Wallis test (α=0.05). In general, a significant decrease in the gutta-percha filled area and increase of sealer area were observed at the apical level for all the evaluated techniques (p<0.05). With regard to the presence of voids, no significant difference was found. MS and TH techniques showed a larger gutta-percha filled area than LC and GF techniques at the coronal and middle third level (p<0.05). From the results of the present study, it may be concluded that the gutta-percha filled area of fillings decrease at the apical level, regardless of the filling technique used.