Comparison of the effects of TripleGates and Gates-Glidden burs on cervical dentin thickness and root canal area by using cone beam computed tomography

The search for new instruments to promote an appropriate cervical preparation has led to the development of new rotary instruments such as TripleGates. However, to the best of the authors' knowledge, there is no study evaluating TripleGates effect on the “risk zone” of mandibular molars. Objectives: The aim of this study was to evaluate the effects of a crown-down sequence of Gates-Glidden and TripleGates burs on the remaining cervical dentin thickness and the total amount of dentin removed from the root canals during the instrumentation by using cone beam computed tomography. The number of separated instruments was also evaluated. Material and Methods: Mesial roots of 40 mandibular first molars were divided into 2 equal groups: crown-down sequence of Gates-Glidden (#3, #2, #1) and TripleGates burs. Cervical dentin thickness and canal area were measured before and after instrumentation by using cone beam computed tomography and image analysis software. Student’s t-test was used to determine significant differences at p<0.05. Results: No significant differences (p>0.05) were observed between the instruments, regarding the root canal area and dentin wall thickness. Conclusion: Both tested instruments used for cervical preparation were safe to be used in the mesial root canal of mandibular molars.

Stress distribution on dentin-cement-post interface varying root canal and glass fiber post diameters. A three-dimensional finite element analysis based on micro-C data

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Evaluation of the Radiopacity of Esthetic Root Canal Posts

The radiopacity of esthetic root canal posts may impair the assessment of their fit to the root canal when using radiographic images. This study determined in vitro the radiographic density of esthetic root canal posts using digital images. Thirty-six roots of human maxillary canines were assigned to six groups (N = 6 per group): Reforpost (RP); Aestheti-Plus (AP); Reforpost MIX (RPM); D.T. Light Post (LP); Reforpost Radiopaque (RPR); and White Post DC (WP). Standardized digital images of the posts were obtained in different conditions: outside the root canal, inside the canal before and after cementation using luting material, and with a tissue simulator. Analysis of variance was used to compare the radiopacity mean values among the posts outside the root canal and among the posts under the other conditions, and the t unpaired test to compare the radiopacity between the posts and the dentin, and between the posts and the root canal space. There was no statistically significant difference in radiopacity between RP and RPM, and LP and WP. AP posts showed radiopacity values significantly lower than those for dentin. No statistically significant difference was found between posts (RP and AP) and the root canal space. A statistically significant difference was observed between the luted and non-luted posts; additionally, luted posts with and without tissue simulator showed no significant differences. Most of the cement-luted posts analyzed in this study were distinguishable from the density of adjacent dentin surfaces, allowing radiographic confirmation of the fit of the post in the canal.Clinical SignificanceThe success of using esthetic root canal posts depends mainly on the fit of the post within the canal.[1] The radiopacity of a post allows for radiographic imaging to be used to determine the fit, an important factor in a clinical perspective.

Investigation of the Effect of Sealer Use on the Heat Generated at the External Root Surface during Root Canal Obturation Using Warm Vertical Compaction Technique with System B Heat Source

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of root canal preparation, type of endodontic post and mechanical cycling on root fracture strength

Objective: To evaluate the impact of the type of root canal preparation, intraradicular post and mechanical cycling on the fracture strength of roots. Material and Methods: Eighty human single rooted teeth were divided into 8 groups according to the instruments used for root canal preparation (manual or rotary instruments), the type of intraradicular post (fiber posts-FRC and cast post and core-CPC) and the use of mechanical cycling (MC) as follows: Manual and FRC; Manual, FRC and MC; Manual and CPC; Manual, CPC and MC; Rotary and FRC; Rotary, FRC and MC; Rotary and CPC; Rotary, CPC and MC. The filling was performed by lateral compactation. All root canals were prepared for a post with a 10 mm length, using the custom # 2 bur of the glass fiber post system. For mechanical cycling, the protocol was applied as follows: an angle of incidence of 45 degrees, 37 degrees C, 88 N, 4 Hz, 2 million pulses. All groups were submitted to fracture strength test in a 45 degrees device with 1 mm/min cross-head speed until failure occurred. Results: The 3-way ANOVA showed that the root canal preparation strategy (p<0.03) and post type (p<0.0001) affected the fracture strength results, while mechanical cycling (p=0.29) did not. Conclusion: The root canal preparation strategy only influenced the root fracture strength when restoring with a fiber post and mechanical cycling, so it does not seem to be an important factor in this scenario.

One-Visit Versus Two-Visit Root Canal Treatment: Effectiveness in the Removal of Endotoxins and Cultivable Bacteria

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Quantification of Endotoxins in Infected Root Canals and Acute Apical Abscess Exudates: Monitoring the Effectiveness of Root Canal Procedures in the Reduction of Endotoxins

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clinical investigation of bacterial species and endotoxin in endodontic infection and evaluation of root canal content activity against macrophages by cytokine production

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Comparative analysis of three rotary instruments used for coronal pre-enlargement in radicular dentin thickness and root canal area of mandibular molars

Purpose: The purpose of this study was to evaluate the increase of the cervical area and dentin thickness in mesial and distal walls of the mesial canals from mandibular molars after the use of LA Axxess (LA), CP Drill (CP) and Gates-Glidden (GG) rotary instruments. Material and Methods: Sixty root canals from thirty mandibular first molar were sectioned 3 mm below the cement-enamel junction, divided in 3 groups (n = 20 root canals, each) according to rotary instrument used, and the cervical images were captured before and after pre-enlargement instrumentation. The increase of the instrumented cervical area (mm2) and the dentin removal thickness (mm), at mesial and distal walls were calculated using Image tools software, by comparison of images. Data were analyzed by ANOVA and Tukey tests (p=0.05). Results: All rotary instruments promoted thickness reduction in dentin walls. In mesial wall, all rotary instruments promoted similar thickness reduction of dentinal wall and did not differ from each other (p>0.05). In distal wall, LA Axxess instrument promoted higher dentin thickness reduction than other groups (p<0.05). The three rotary instruments promoted different increase at the instrumented cervical area (p<0.05), LA promoted the highest increase area and GG and CP presented similar results. Conclusion: LA 20/0.06 promoted the highest thickness reduction in distal wall and increase of cervical area of root canal. On the other hand, CP was the safest instrument, with lower dentin removal of distal wall and similar increased area to GG.

Antimicrobial activity of root canal irrigants associated with cetrimide against biofilm and planktonic Enterococcus Faecalis

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A method for retrieving endodontic or atypical non-endodontic separated instruments from the root canal: a report of two cases

Aim: This clinical report presents a new method for retrieving separated instruments from the root canal with minimally invasive procedures. Background: The presence of separated instrument in root canal may interfere in the endodontic treatment prognosis. There are several recommended methods to retrieve separated instruments, but some are difficult in clinically practice. Case report: This study describes two cases of separated instrument removal from the root canal using a stainless-steel prepared needle associated with a K-file. Case 1 presented a fractured gutta-percha condenser within the mandibular second premolar, it was separated during incorrect intracanal medication calcium hydroxide placement. Case 2 had a fractured sewing needle within the upper central incisor that the patient used to remove food debris from the root canal. After cervical preparation, the fractured instruments were fitted inside a prepared needle and then an endodontic instrument (#25 K-file) was adapted with clockwise turning motion between the needle inner wall and the fragment. Conclusion: The endodontic or atypical nonendodontic separated instrument may be easily pull on of the root canal using a single and low cost device. Clinical significance: The methods for retrieving separated instruments from root canal are difficult and destructive procedures. The present case describes a simple method to solve this problem.

Effect of sodium hypochlorite under several formulations on root canal dentin microhardness

Aim The aim of the present study was to evaluate the effect of three different formulations of sodium hypochlorite on the microhardness of root canal dentin in cervical and apical segments. Methods Twenty-four extracted human teeth had their roots sectioned along their long axes in a buccolingual direction. One half of each root was selected, and transversely sectioned resulting in two segments, cervical and apical, with similar lengths. The specimens were divided into three groups (n = 16), according to the sodium hypochlorite formulation used: (a) group 1, 2.5% sodium hypochlorite; (b) group 2, Chlor-XTRA; and (c) group 3, 5.5% sodium hypochlorite gel. These groups were subdivided in two subgroups (n = 8): cervical and apical root segments. Before testing the substances, dentin microhardness was measured on each section, 100 μm from the root canal with a Knoop tester. After 15 min of application, a new measurement was performed on each segment. Data were collected and registered for statistical treatment. Results In both segments, the substances reduced dentin microhardness. No differences were observed between the groups, independent of the analyzed segment (P > 0.05). Conclusions All substances reduced dentin microhardness. Chlor-XTRA and 5.5% sodium hypochlorite gel promoted a reduction similar to the 2.5% sodium hypochlorite solution.

Influence of the rotary and/or oscillatory reciprocating systems in the morphological changes of narrow and curved molar root canals anatomy

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of Sealer Placement Technique on the Quality of Root Canal Filling by Lateral Compaction or Single Cone

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)