Tauby de Souza Coutinho-Filho

Limited ability of three commonly used thermoplasticized gutta-percha techniques in filling oval-shaped canals.

The present study was designed to compare the percentage of gutta-percha-filled area (PGFA) achieved in oval-shaped canals after filling by 3 thermoplasticized techniques. Eighty-seven oval-shaped root canals were prepared and root-filled as follows: lateral condensation (n = 20), thermomechanical compaction (n = 20), wave of condensation (n = 20), and Thermafil system (n = 20). A cross section of each tooth was made 5 mm from the apex, and the samples were prepared for microscopic analysis. Digital image measurements of the cross-sectioned area of the canal and the gutta-percha were performed, and the PGFA was calculated. Nonparametric statistical analysis was performed with the Kruskal-Wallis H test and post hoc Dunn test. Overall, PGFAs were variable among the experimental groups, ranging from 37.1%-98.5%, and the pooled data from all techniques had a general mean of 69.6% +/- 18%. Thermafil system, wave of condensation, and thermomechanical compaction produced significantly higher PGFAs than lateral condensation (P < .05); however, no significant differences among these techniques were detected (P > .05). Therefore, a limited ability to fill oval-shaped canals was achieved in the 3 thermoplasticized techniques tested.

Strong effect on dentin after the use of high concentrations of citric acid: An assessment with co-site optical microscopy and ESEM

OBJECTIVES To perform a longitudinal analysis of the effect of four substances (citric acid at 1%, 5% and 10% concentrations and 17% EDTA) on dentin. METHODS Sixteen human molars had their crowns removed exposing cervical root dentin. A grinding procedure was used to produce a standardized smear layer and to create a smooth surface for analysis. Environmental scanning electron microscopy (ESEM) was used for qualitative observations while co-site optical microscopy (CSOM) and image analysis (IA) provided a quantitative comparison of the effect of the substances for several experimental times from 15 to 300s. The methods allowed the observation of the same areas after each experimental time. The open tubule area fraction was measured for several CSOM image fields, at each experimental time, for the four substances. Thus, it was possible to follow the phenomenon and quantitatively analyze the effect of the substances. Kolmogorov-Smirnov, Kruskal-Wallis H and Wilcoxon signed-ranks (with Bonferroni correction) tests were used to analyze the data. The level of significance was set at p<0.05. RESULTS The CA solutions showed the greatest chelating effect, which was proportional to concentration (EDTA: 9.4-32.8% (15-300s); 1% CA: 21.1-32.2% (15-300s); 5% CA: 32.4-43.1% (15-300s); 10% CA: 35.1-39.5% (15-30s). Erosive effects were observed on inter and peritubular dentin for 5% CA and 10% CA after 60s. SIGNIFICANCE ESEM allowed a detailed qualitative comparison of the effect of the four substances. CSOM and IA provided a quantitative comparison method with good statistical significance. Future studies should focus on the consequences of dentin erosion caused by citric acid.

Radiopacity and histological assessment of Portland cement plus bismuth oxide

OBJECTIVE The present study evaluated the subcutaneous connective tissue reactions and the radiopacity of MTA, Portland cement (PC), and Portland cement plus bismuth oxide (BO). STUDY DESIGN Forty rats were divided into 5 groups (n = 8 per group): A1: Control (empty capsule); A2: Pro-Root MTA; A3: PC; A4: PC + BO 1:1; and A5: PC + BO 2:1. Polyethylene tubes were filled with the test materials and standardized radiographic images were taken. Histological evaluation was done after 7 and 60 days. Student t test and Fishers test were used in the statistical analysis (P < .05). RESULTS The radiopacity of the materials were in decreasing order: A2 > A4 > A5 > A3. No differences were found for the tissue response in the 2 experimental periods. A positive correlation between BO concentration and radiopacity of PC was determined. CONCLUSION The histological evaluation suggests that all studied materials were biocompatible at 7 and 60 days.

Postoperative Pain after Foraminal Enlargement in Anterior Teeth with Necrosis and Apical Periodontitis: A Prospective and Randomized Clinical Trial

INTRODUCTION The aim of this randomized, controlled, prospective clinical study was to determine if foraminal enlargement instrumentation during endodontic treatment is associated with more postoperative pain compared with standard nonenlargement instrumentation. METHODS Forty volunteers with a single root canal were diagnosed with asymptomatic necrosis with apical periodontitis and randomized into 2 experimental groups (ie, the control group and the foraminal enlargement group). Endodontic treatment was performed in a single visit, and volunteers were instructed to record pain intensity (ie, none, slight, moderate, and severe). Scores from 1 to 4 were attributed to each kind of pain after 12, 24, and 48 hours. The Kolmogorov-Smirnov and Students t tests were used to determine significant differences at P < .05. RESULTS No statistically significant age difference was found between the groups (P > .05, Students t test). Postoperative pain showed no statistically significant difference between the groups at any observation period (P > .05). Also, no significant difference was observed in the mean number of analgesic tablets used between the groups (P > .05). CONCLUSIONS The foraminal enlargement and nonenlargement techniques resulted in the same postoperative pain and necessity for analgesic medication. This may suggest that the use of foraminal enlargement should be performed for endodontic treatment previsibility without increasing postoperative pain.

Analysis of the film thickness of a root canal sealer following three obturation techniques

The aim of this study was to obtain a quantitative analysis of the film thickness of a root canal sealer formed after filling by three different techniques. Thirty human maxillary incisors were selected and access cavities were prepared using high-speed diamond stones and water spray. A size #15 K-Flexofile was introduced in the canal of each specimen until it was seen just at the apical foramen. The working length was determined to be 1 mm short of that position and the canals were prepared to an apical size of #45 K-Flexofile. Copious irrigation with 5.25% NaOCl (sodium hypochlorite) was used during and after instrumentation. The samples were divided into three groups and obturated as follows: G1 - lateral condensation, G2 - lateral condensation with an accessory cone, and G3 - continuous wave of condensation. The samples were evaluated in the cervical, middle and apical thirds. The film thickness of the root canal sealer was measured through a microscopic evaluation. Statistical analysis was obtained using the Wilcox test. Statistical analysis showed significant differences between G3 and G1, G3 and G2 (p < 0.05). In general, the lowest film thickness was observed in the continuous wave of condensation (G3). Lateral condensation with an accessory cone (G2) and lateral condensation (G1) demonstrated poorer results in this study, showing a higher film thickness. The small film thickness of the sealer obtained by the continuous wave of condensation technique may increase the clinical performance of this technique.

Evaluation of the risk of a stripping perforation with gates-glidden drills: serial versus crown-down sequences

The aim of this study was to evaluate the remaining dentine/cementum thickness using Gates-Glidden burs in serial and crown-down sequences and to observe which of the two sequences is the safest for preparing mesial roots of molars. Thirty-six left and right human mandibular first molars were selected. Standard access cavities were made and initially explored with Flexofiles sizes 10 and 15 until the tip was visible at the apex. The teeth were embedded in a muffle specially developed for this study using a PVC tube with two parallel metal rods in its lid. Each tooth-block was sectioned 3 mm apically to the furcation using a low-speed saw with a diamond disc. The tooth-block was examined under a microscope and an initial image was captured by a digital video system with 8 X and 12 X magnifications. Finally, the tooth-blocks were reassembled in the muffle so that the canals could be instrumented. After instrumentation the area of each mesial canal as well as the smallest distance to the root furcation were measured again. The mesio-buccal canals (crown-down order) and the mesio-lingual canals (serial sequence) presented an average area of 0.46 +/- 0.16 mm(2) and 0.88 +/- 0.27 mm(2) (P < 0.01), respectively. The mean values of the smallest distance to the furcation for the mesio-buccal and mesio-lingual canals were 0.66 +/- 0.19 mm and 0.39 +/- 0.13 mm (P < 0.01), respectively. The remaining dentine/cementum thickness using Gates-Glidden burs was greater in the crown-down sequence than in the serial sequence.

A multiparametric assay to compare the cytotoxicity of soy milk with different storage media.

BACKGROUND/AIM The aim of this study was to evaluate the cytotoxicity of soy milk compared with several other storage media [coconut water, Hanks Balanced Salt Solution (HBSS) and whole milk], assessed through a multiparametric analysis employing 3T3 cells. MATERIALS AND METHODS Plates containing confluent 3T3 fibroblasts were exposed to the various media for 24 h, at 37°C with 5% CO₂, and cell viability was evaluated by a multiparametric assay assessing sequentially, on the same cells, mitochondrial activity (XTT), membrane integrity (neutral red test) and total cell density (crystal violet dye exclusion test). Results from each test were compared by two-way analysis of variance (ANOVA). RESULTS Statistical analysis showed that whole milk, HBSS and soy milk were the most effective media in maintaining cell viability at all tested times (P < 0.05). The least amount of viable cells was observed when using coconut water. CONCLUSIONS This study shows that the efficacy of soy milk in maintaining the viability of 3T3 fibroblasts is similar to that of HBSS and milk, as shown by three different cell viability tests.

Evaluation of the Joypex 5 and Root ZX II: an in vivo and ex vivo study

AIM To evaluate in vivo and ex vivo the accuracy of the multifrequency electronic root canal length measurement device (ERCLMD) Joypex 5 and compare it with the Root ZX II. The ex vivo methodology for evaluation of the accuracy of ERCLMDs was also validated by comparison with in vivo results. METHODOLOGY Twenty single-rooted human teeth that were scheduled for extraction were selected. Working length measurements were performed in vivo with the Joypex 5 and Root ZX II. After the teeth were extracted, each canal was measured with the ERCLMDs ex vivo. Then, a size 15 K-file was used to determine the reference working length (RWL), which was established 0.5 mm from the major foramen by direct observation. The measurements of working length obtained with the different methods and ERCLMDs were compared by analysis of variance and Tukeys test at P < .05. Statistical correlations were also performed. RESULTS No significant difference was observed between in vivo and ex vivo measurements or the different types of ERCLMDs. The Bland-Altman plot confirmed the agreement of different methods and ERCLMDs to measure canal length. The R(2) coefficient obtained in both situations, comparing the ERCLMDs, was close to 1, denoting a strong agreement between measurements obtained with the Joypex 5 and Root ZX II and between in vivo and ex vivo methodologies. CONCLUSION The Joypex 5 and Root ZX II had similar accuracy in determining working length of root canals. The ex vivo methodology for evaluation of the accuracy of ERCLMDs was validated when compared with the in vivo results.

Use of soymilk as a storage medium for avulsed teeth.

Abstract Objective. Tooth avulsion is one of the most severe forms of dental trauma. In these cases, immediate reimplantation is ideal; however, it almost never happens. The purpose of this study was to evaluate the viability of cells stored in soymilk and compare with other several storage media. Materials and methods. The media tested were: long-shelf-life coconut water, long-shelf-life whole milk, long-shelf-life soymilk, Gatorade, egg white, and Hanks Balanced Salt Solution. Cells cultured in DMEM and distilled water served as positive and negative controls, respectively. Plates containing confluent 3T3 fibroblast were soaked in the various media for 2, 12 and 24 h. After incubation at 37°C, viability of the cells was determined using the MTS assay. Data were analyzed by using one-way ANOVA and complemented by Tukey test with a significance level of 5%. Results. Statistical analysis showed that DMEM, whole milk, HBSS and soymilk were the most effective media for maintaining cell viability at all tested times (p < 0.05), followed by coconut water, egg white and Gatorade. The least amount of viable cells was observed in the distilled water group. Conclusions. The present study shows that the efficacy of soymilk in maintaining the viability of 3T3 fibroblasts is similar to that of HBSS and milk. Therefore, it can be concluded that soymilk could be a suitable alternative storage medium for avulsed teeth.

Influence of Apical Preparation Size and Working Length on Debris Extrusion

The aim of this study was to quantitatively evaluate the amount of apically extruded debris by single-file reciprocating instruments with different working lengths and apical preparation sizes. Eighty human single-rooted mandibular incisors were used and conventional access cavities were prepared. Then, the specimens were divided into four groups (n=20), according to root canal instrumentation: Reciproc size 25, .08 taper and Reciproc size 40, .06 taper instruments were used at the foramen; Reciproc size 25, .08 taper and Reciproc size 40, .06 taper instruments were used 1 mm short of the foramen. Distilled water was used as an irrigant and the apically extruded debris were collected in pre-weighted glass vials and dried afterwards. The mean weight of debris was weighed with a microbalance and statistically analyzed using one-way analysis of variance and the post hoc Tukey multiple comparison test (p<0.05). The results showed that all experimental groups were associated with debris extrusion. No significant difference was found in the amount of apically extruded debris among all experimental groups (p>0.05). The present study demonstrated that the working length and the apical preparation size did not have a significant effect on debris extrusion when performing single-file reciprocating instrumentation.