Benjamín Briseño Marroquín

Morphology of the Physiological Foramen: I. Maxillary and Mandibular Molars

Information concerning the anatomy of the physiological foramen is limited. The aim of this study was to investigate the distance between the physiological and anatomical apex, accessory foramina frequency, and the shape and diameter of the physiological foramen in maxillary and mandibular molars. The apical anatomy of 523 maxillary and 574 mandibular molars from an Egyptian population was investigated by means of a computer-aided stereomicroscope (40 x magnification). The following results were obtained:

Cytotoxicity of Root Canal Filling Materials to Three Different Human Cell Lines

The aim of this study was to investigate the biological compatibility of five root canal sealers (Sealapex, Endion, Super-EBA, Ketac-Endo, and AH Plus) and regular and calcium hydroxide-based gutta-percha in three different human cell lines. Cultures without root canal sealers were used as controls. Cell growth, cell morphology, cell viability, protein content of the cells, and prostaglandin E2 (PGE2) release were used as parameters to determine the cytotoxicity of the materials. The protein content of the three cell lines--nasal fibroblasts, gingival fibroblasts, and epithelial tumor cells--was significantly reduced (p < or = 0.001) by all materials tested. Determinations of PGE2 release showed significant material specific differences. No significant increased PGE2 release values were found with Sealapex, Endion, and Super-EBA. On the contrary significantly increased PGE2 levels were measured with Ketac Endo, AH Plus, regular and calcium hydroxide-based gutta-percha points (p < or = 0.001).

Influence of a bioceramic root end material and mineral trioxide aggregates on fibroblasts and osteoblasts.

OBJECTIVE The biocompatibility of materials used in endodontic treatment is of high importance, because they can come in contact with periradicular tissues and there is a risk of possible systemic toxicity. The aim of the present study was to investigate the in vitro reaction to a bioceramic based root end material in comparison to mineral trioxide aggregates (MTA) as the established gold standard. DESIGN The root end materials grey MTA Angelus (GMTA), white MTA Angelus (WMTA), ProRoot MTA, and EndoSequence Root Repair Material (ERRM) were incubated with human periodontal ligament fibroblasts and osteoblasts (10(4)cells/ml) for up to 96h. Cell proliferation (RFU) was determined by means of the Alamar Blue assay. In addition, fluorescence staining was carried out to visually monitor cell growth and morphology. RESULTS For most of the observational time period of up to 96h, there was no statistically significant difference between the proliferation rates of the control cells and those in contact with ERRM. In contrast, the mineral trioxide based materials caused from 24 to 96h significantly lower proliferation rates in comparison to the controls (p<0.001). For proliferation rates of cells in contact with MTAs and ERRM significant differences were observed throughout the whole observation time for the osteoblasts, but only up to 24h for the human periodontal ligament fibroblasts. CONCLUSION Within the limits of this study the results suggest that the bioceramic root end material is biocompatible, but needs to be investigated in clinical studies before it can be recommended as retrograde sealer in endodontic practice.

Radiographic investigation of frequency and location of root canal curvatures in human mandibular anterior incisors in vitro.

The aim of the present in vitro study was to evaluate the degree and location of root canal curvatures of mandibular anterior incisors. A total of 396 extracted human permanent anterior incisors (248 central and 148 lateral) were included in this investigation. Exclusion criteria were teeth with extensive carious lesions, restorations, and root canal treatment. The specimens were fixed in a special device and digitally x-rayed (Heliodent MD; Sirona, Benzheim, Germany; Merlin 2.1, Olympus/PerkinElmer, Waltham, MA) with the parallel technique. The distances from the cementoenamel junction (CEJ) to the first curvatures as well as the according angles were recorded. The results were analyzed descriptively, and p values were calculated with the Wilcoxon test. The mean distance between the CEJ and the first curvature of the central anterior incisors was 13.8 mm (standard deviation +/- 2.6) and that of the lateral anterior incisors was 12.3 (standard deviation +/- 2.5), respectively. A total of 82 (33.1%) central and a total of 118 (79.7%) lateral anterior incisors exhibited curvatures. No statistically significant differences between left and right anterior incisors could be observed regarding the canal curvature locations (p < 0.001) and the angle values (p < 0.04). The results showed a high percentage of mandibular anterior incisors with a mean curvature located 13 mm apically from the CEJ. The findings of this study may enhance the predictability of endodontic treatment and minimize errors during post insertion.

Canal transportation caused by a new instrumentation technique and three standard techniques

The ability of three different enlarging techniques (balanced force concept, step-back, and recapitulation) and a prototype system to maintain the original canal path during root canal preparation were compared, in vitro, with a theoretical ideally prepared root canal. Measurements were made at the concave and convex sides of the canal at four different levels (1, 4, 5, and 7 mm from apical, respectively). Simulated root canals embedded in clear casting resin and an enlarging computer-supported device were used for this study. The results showed that none of the enlarging techniques used in this study was able to prepare a canal ideally. The prototype system, at level 1, showed an ideal amount of material removed from the concave side and less, in comparison with the other techniques, from the convex side of the canals. The same tendencies persisted at all levels, with the exception of the level 4 concave side.

Thermoplastic Properties of Endodontic Gutta-percha: A Thermographic In Vitro Study

INTRODUCTION Endodontic gutta-percha undergoes deformation at temperatures above 65°C. The temperature influence of heat carriers on gutta-percha cones was investigated in vitro. METHODS Six single-rooted extracted teeth were embedded in resin and fixed. The root canals were prepared (ProFile; Dentsply Maillefer, Ballaiques, Switzerland) to different tapers and bisected. Thermographic images when heating the gutta-percha cones (Roeko, Langenau, Germany) with a heat carrier (ML .12; SybronEndo, Orange, CA) at 1 and 5 mm from the working length were made with an infrared thermal imaging camera (ThermaCam P640; Flir Systems, Täby, Sweden). The device temperature was preset at 200°C. The pixel temperature registered at the contact lines between the heat carriers and gutta-percha cones in the thermographic images was recorded and statistically described. RESULTS A mean temperature (°C) instability in the heat carrier (324.96 ± 46.10, minimum = 147.35, maximum = 474.13), a temperature drop of the gutta-percha cones (159.52, ± 37.57, min 67.64, max 259.04) at the measuring level, and a mean temperature penetration depth (mm) equal or to higher than 65°C (1.05 ± 0.28, minimum = 0.20, maximum = 1.30) were recorded. No correlation between the penetration depth into the gutta-percha cones and applied temperatures, regardless of the size and/or taper, could be established. CONCLUSIONS Temperature discrepancies between the device preset and achieved ones of the heat carriers was observed. Gutta-percha is a poor thermal conductor, transports heat irregularly, and should be heated 1-2 mm from the target area.

Accuracy of electronic apex locators to detect root canal perforations with inserted metallic posts: an ex vivo study

IntroductionThe detection of possible root canal perforations caused during a metal post placement is frequently difficult to diagnose. The aim of this study was to investigate the accuracy of apex locators to diagnose such perforations.Materials and methodsThirty mesiolingual root canals of extracted mandibular molars were instrumented (30/.04) and a post space was prepared. A root canal perforation was intentionally made at the bi-furcation (n = 15). Metal posts were cemented in 15 perforated and 15 non-perforated root canals. The teeth roots were embedded in an agar-agar solution. The resulting measurements (“short” or “beyond” the apex) disclosed if a perforation could be identified with five different apex locators (ProPex II, Elements Apex Locator, Apex NRG, Raypex 5 and Raypex 6). The sensitivity and specificity (95% interval confidence) were calculated.ResultsAll devices excluded the absence of perforations (100% with 95% confidence interval [78%; 100%] specificity). The Apex NRG and Raypex 6 detected all perforations (100% with 95% confidence interval [78%; 100%] sensitivity). The ProPex II, Elements Apex Locator, and Raypex 5 detected 14 out of 15 perforations (93% with 95% confidence interval [68%; 100%] sensitivity).ConclusionsAll devices determined root canal perforations, due to metallic posts, within clinical acceptable ranges.

Evaluación de la citotoxicidad de distintos cementos selladores endodónticos en cultivos de fibroblastos gingivales

El objetivo de esta investigacion fue evaluar in vitro la respuestade fi broblastos gingivales contra diferentes selladores endodonticosmediante cultivos celulares, en un lapso de 96 horas. Los resultadosobtenidos a intervalos de tiempo de 0, 1, 2, 3, 6, 24, 48, 72 y96 horas fueron utilizados para determinar la citotoxicidad de losselladores. Cultivos de fi broblastos gingivales sin ningun sellador ycon Sealapex fueron utilizados como controles positivos y negativosrespectivamente. Los resultados fueron comparados con los controlesnegativos y analizados estadisticamente por medio de la pruebat Dunnett (p ≤ 0.05). Los cementos selladores investigados fueron:ProRoot MTA gris y blanco CPM, MTA Angelus, Sealapex y Gutta-Flow. Los resultados demostraron que a pesar de que el ProRootMTA (gris y blanco) MTA Angelus, CPM y GuttaFlow demostrarontener un potencial citotoxico menor que el Sealapex, no se encontrarondiferencias estadisticas signifi cativas.