CBCT Assessment of Root Dentine Removal by Gates-Glidden Drills and Two Engine-Driven Root Preparation Systems

Dentine Thickness of Second Mesibuccal Canals in First Maxillary Molars Prepared with Rotary Instruments

Introduction

The purpose of this study was to evaluate the thickness of the remaining dentine wall in the danger zone of the second mesiobuccal (MB2) canals using cone-beam computed tomography (CBCT) in maxillary first molars following preparation by means of HERO 642 rotary instruments with different tapers.

Methods and Materials

The study samples included twenty-five mesiobuccal roots of maxillary first molars. A two-step method was employed to prepare the MB2 canals applying HERO 642 instruments: using a 0.02 taper (step 1), and a 0.04 taper (step 2). The roots were scanned before preparation, and after each step. The thickness of the dentine wall was recorded at the CEJ level, as well as 2 mm and 4 mm below the CEJ. The repeated-measures ANOVA in conjunction with the Cochran tests were used to compare the changes in the thickness of the root canal wall.

Results

There was no area with dentine thickness of <0.5 mm before preparation. A significant reduction in dentine thickness occurred following the preparation with both 0.02 and 0.04 files at all three levels compared with the pre-instrumentation values (P< 0.05). However, areas with dentine thickness of < 0.5 mm after preparation using 0.04 files were significantly more than those resulting from the application of 0.02 files both at the CEJ and 2 mm-below-CEJ points, but the differences were not significant at the 4mm-below-CEJ level.

Conclusion

Within the limitations of the present in vitro study, the use of larger taper instruments in MB2 root canals of maxillary first molars increased the quantity of samples with dentine thickness less than 0.5 millimeter at the coronal level of the root canal. It was concluded that instruments with large tapers, should be used with caution in troughing or preparing such root canals to reduce the risk of strip perforation.

Comparing the amount of removed dentin thickness in root canal treated primary molar teeth using different instrumentation techniques: in-vitro study using CBCT

PURPOSE

There is a clinical dilemma about root canal preparation for endodontic treatment of primary teeth. This study aimed to compare the amount of dentin removal in root canal treated primary molar teeth with three preparation techniques by cone-beam computed tomography (CBCT).

METHODS

A total of 39 s primary molar teeth were selected with a minimum of two-thirds of the entire root length. Access cavity was prepared and preliminary CBCT images were taken and viewed by Romexis programme. The wall thickness of the canal was measured in the danger zone at two axial cut sections of 1 and 2 mm below furcation. Then, the teeth were instrumented with three different methods as manual K-files (size 15-30), Gates glidden burs (in decreasing order of size #2 and #1 followed by hand k-files up to file number 25), and ProTaper rotary files. After canal preparation, the specimens were placed in the same position, and the canal wall thickness was remeasured. Data were analysed by using one-way ANOVA and Kruskal-Wallis tests (α = 0.05).

RESULTS

The amounts of removed dentin thickness was not significantly different among the three groups at two axial cut sections of 1 mm and 2 mm below furcation (P = 0.27 and 0.17, respectively).

CONCLUSION

Within the limitations of this study, the three instrumentation techniques used in primary molars were comparable regarding the amount of dentin removal.

Evaluation of remaining dentin thickness following use of three different rotary nickel-titanium retreatment files: A cone-beam computed tomography study

Aim:

The aim of the study is to measure the amount of remaining dentin thickness (RDT) following retreatment using three different rotary nickel–titanium (NiTi) systems.

Methodology:

Mesiobuccal roots of 45 extracted maxillary first molars were prepared up to F₂ ProTaper File and obturated. After cone-beam computed tomography (CBCT) imaging, to evaluate the obturation, the samples were randomly assigned to three retreatment groups (n = 15). Group I was retreated with ProTaper Universal retreatment kit, Group II and III with M_TWO and D-Race retreatment files, respectively. Postoperatively, all samples were subjected to CBCT imaging and evaluated with AutoCAD software (AutoDesk, Inc.) Mill Valley, California, U.S. to calculate the RDT. Data were statistically analyzed using one-way ANOVA and Tukey's post hoc tests, and the level of significance was set at P = 0.05.

Results:

The amount of RDT was significantly more in D-Race and M_TWO groups when compared to ProTaper group.

Conclusion:

D-Race and M_TWO instruments were associated with significantly more RDT than ProTaper.

A Novel Hybrid Hand Instrumentation Technique for Root Canal Preparation

Introduction

Preparation of root canal system necessitates both enlargement and shaping of the complex root canal space together with disinfection of the easily accessible and hidden areas. The present article introduces a new manual root canal preparation technique and compares it with passive step-back and step-back regarding some items such as shaping efficacy, maintenance of working length and occurrence of procedural accidents.

Methods and Materials

This canal preparation technique (Bolourchi Hybrid Technique-BHT) was compared with passive step-back and step-back root through preparation of 30 extracted human mandibular and maxillary molars. Three experienced endodontists evaluated the final radiographies for following items: 1) difficulty of the case 2) shaping efficacy 3) maintenance of working length 4) time of preparation. Two-way ANOVA was used to analyze the data. Multiple comparisons were done using the Tukey's HSD.

Results

Regarding shaping efficacy and maintenance of working length, BHT group showed significantly higher scores and scores for step-back group were significantly the lowest. The difference between BHT group and passive step-back on these items was not significant. No significant differences were found between the techniques in other assessed criteria except for occurrence of procedural accidents which was significantly higher in step-back group.

Conclusion

Considering the advantages of this novel technique as well as its comparability to the present routine techniques, it can be considered as an available root preparation technique for teaching in dental schools.