Renato Liess Krebs

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.

EVALUATION OF PHOTODYNAMIC THERAPY USING A DIODE LASER AND DIFFERENT PHOTOSENSITIZERS AGAINST ENTEROCOCCUS FAECALIS

Photodynamic therapy (PDT) has been proven to be effective in disinfecting root canals. The aim of this present study was to evaluate the effects of PDT on the viability of Enterococcus faecalis using methylene blue (MB) and malachite green (MG) as photosensitizers. Solutions containing E. faecalis (ATCC 29212) were prepared and harvested by centrifugation to obtain cell suspensions, which were mixed with MB and MG. Samples were individually irradiated by the diode laser at a distance of 1mm for 30, 60, or 120 seconds. Colonyforming units (CFU) were determined for each treatment. PDT for 60 and 120 seconds with MG reduced E. faecalis viability significantly. Similar results were obtained when MB was used as photosensitizer. PDT using MB and MG have antibacterial effect against E. faecalis, showing potential to be used as an adjunctive antimicrobial procedure in endodontic therapy.

A comparative evaluation of efficacy of a reciprocating system for gutta-percha removal with or without a solvent

Objective: to evaluate the efficacy of Reciproc System, with or without solvent for endodontic filling removal from oval shaped root canals. The time required for gutta-percha removal and the instrument fracture were also evaluated. Material and Methods: forty straight single-rooted premolars were prepared up to a size 30 and filled with gutta-percha and sealer, then randomly assigned to two retreatment groups (n = 20), treated with Reciproc System with or without chloroform (RS+C and RS). For all roots, procedural errors, time of retreatment and apically extruded material were recorded. After retreatment, roots were split longitudinally and then photographed. All images were evaluated with Image Tool software to calculate the percentage of residual material. Kolmogorov Smirnov and t tests were used to determine significant differences at P < .05. Results: no treatment completely removed the root filling material from the root canals. Analysis of the total area did not reveal statistical differences between the two groups (P >.05). Both groups also showed similar results in all tested thirds, with no statistical differences (P >.05). RS without solvent was faster in filling material removal than RS+C (P <.05). For both groups, none of the instruments showed intracanal fracture or visible signs of plastic deformation. Conclusion: taken together, our results demonstrated that Reciproc System used without solvent required less time to remove the same amount of root filling material than Reciproc System with solvent. However, regardless of solvent use, the same cleaning quality was obtained.

A multiparametric assay to compare the cytotoxicity of different storage media for avulsed teeth

AIM: To evaluate the cytotoxicity of several storage media (coconut water, whole milk, isotonic solution, Hank´s Balanced Salt Solution and tap water) using a multiparametric cytotoxicity analysis employing 3T3 cells. METHODS: Plates containing confluent 3T3 fibroblasts were exposed to the various media for 24h, 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 one-way analysis of variance (ANOVA). RESULTS: Statistical analysis showed that whole milk and HBSS were the most effective media in maintaining cell viability at all tested times (p<0.05). Isotonic and tap water showed the highest cytotoxicity effects. CONCLUSIONS: This study shows that whole milk and HBSS are more efficient in maintaining the viability of 3T3 fibroblasts as demonstrated by three different cell viability tests.