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The aim of this study was to compare, in vitro, the machining efficiency of different triangular cross-section K-files made of nickel titanium (Nitiflex, Naviflex), titanium (Microtitane), and stainless steel (Flexofile, Flex-R). Ten instruments of each K-file from size 25 to 40 were tested. The cutting efficiency was assessed in a linear motion using an indentation caliper to measure the depth of grooves. The load applied (in grams) was equal to the ISO file size. Each file was allowed to do 100 back-and-forward movements. Files made of stainless steel were the most effective, in particular Flexofile. There were statistically significant differences between Flexofile and Flex-R in all sizes. In the group of nickel titanium instruments, Nitiflex was significantly more efficient than Naviflex in all sizes. The machining ability of titanium files was higher than that of Naviflex but lower than that of Nitiflex and stainless steel files. [ABSTRACT FROM AUTHOR]

Damage to the inferior alveolar nerve is a relatively infrequent complication in dental practice. When root canal treatment of a lower molar or premolar surpasses and/or overextends beyond the apical foramen and invades the periapical zone, the foreign material introduced within such a sensitive anatomical space may mechanically or even chemically affect the inferior alveolar nerve. We describe a case of endodontic treatment of a permanent right lower first molar in which the sealer cement overextended in large amounts and damaged the right inferior alveolar nerve. The condition reverted a few months after the surgical removal of the material. Evaluation of the removed material, using powder x-ray diffraction and scanning electron microscopy with coupled dispersive energy spectroscopy, showed it to consist of calcium tungstate (scheelite [CaWO4]) and zirconium oxide (baddeleyite [ZrO2]), which were chemical components of the sealer cement.

Dentinal tubules are the means by which the pulp and mineralised tissues surrounding the dentine (enamel and cementum) communicate. Through these tubules external agents can damage the pulp and subsequently the periodontal ligament. Given the importance of dentinal tubules, the authors evaluated the numerical density, shape, and individual surface area of tubule openings and the percentage of dentine occupied by these. Eight permanent upper premolars were studied using scanning electron microscopy (SEM). In the crown, the external surface of the dentine was evaluated at the dentino-enamel junction and the internal surface at the pulp chamber wall. At the cervical, middle and apical thirds of the root, the external surface was evaluated at the cemento-dentinal junction and the internal surface at the root canal wall. The results showed that numerical density of tubule openings is significantly greater (p < 0.05) at the cervical third of the dentine, at its junction with the cementum and at the pulpal chamber wall, with respect to other areas evaluated. The individual surface area of each opening varied from 5.72 microns 2 in the dentine of the pulpal chamber wall to 0.97 micron 2 in the dentine of the apical third of the root canal wall. The percentage of area occupied by the dentinal tubules per mm2 of dentine was significantly higher (p < 0.01) at the internal dentinal surface as compared to the external. The shape of the tubule openings was found to be circular in the crown and became more irregular as the apical third of the root was approached.

A comparative study of the absorbency properties of different endodontic paper points has been conducted. Twenty standardized absorbent paper points, size 30, from 13 bands (Dentaline, Zipperer, Kerr, Diadent, Roeko novo, Roeko color, Maillefer, P.D., Schein, Spectrapoint, Proclinic, Euronda, and Alpro) of 12 manufacturers were tested. Each dry paper point was weighted using an electronic laboratory balance. A length of 16 mm from the tip was then lowered in distilled water for 5 s, the paper point was weighted again, and the difference between both measurements was taken as the value of the fluid absorbed. Diadent, Kerr, and Dentalite showed significantly higher absorbencies (p < 0.05) than standardized paper points of the remaining brands. The study demonstrates a wide variation in the absorbency properties of this dental accessory.

This study was conducted to compare the apical sealing capacity of three filling techniques, a multiphase gutta-percha obturation technique, JS Quickfill, and lateral gutta-percha condensation. A four-stage stepback preparation was executed with circumferential filing in a total of 70 recently extracted permanent maxillary incisors and canines. Three experimental groups (20 teeth in each group) and two control groups (5 teeth in each group) were formed at random. Each experimental group was obturated with a different technique. The positive control group was not obturated. In the negative control group, the whole root was covered with two full nail varnish layers. Teeth were immersed in India ink for 48 h, demineralized, cleared with methyl salicylate, and examined with a stereomicroscope. None of the specimens obturated with the multiphase gutta-percha obturation system showed any penetration of India ink beyond the end of the preparation. In the groups of teeth obturated by JS Quickfill or lateral gutta-percha condensation, leakage was detected in one specimen from each group. No statistically significant differences were seen among groups. We conclude that the newer thermoplasticized filling techniques can be used successfully to obturate root canals in large, straight roots.

Six different instruments (Flexofile, Canal Master U, Heliapical, Flexogate, Ultraflex, and Lightspeed) were evaluated in 240 mesial canals of extracted mandibular molars (40 canals per instrument type). After instrumentation, the roots were cross-sectioned 2, 5, and 9 mm from the apex. The cross sections were evaluated to determine the quality of canal preparation (round, oval, irregular). The best results were obtained with nickel-titanium, a short cutting blade and a rotary rather than a filing motion. The Canal Master U, Flexogate, and Lightspeed instruments had significantly more round canals than the Flexofile, Heliapical and Ultraflex instruments at all levels. The Lightspeed had the largest number of round canals at all levels. Instrumentation time was also recorded. The Canal Master U and Flexogate were significantly slower than the Flexofile, heliapical, Ultraflex, and Lightspeed instruments. There were no statistically significant differences within the faster group.

The purpose of this study was to assess and to compare the torsional and bending properties of the Canal Master U (CMU) and Flexogate instruments made of stainless steel and nickel titanium. The bending moment, the torsional moment and angular deflection were measured according to ANSI/ADA specification number 28 and ISO reference number 3630. Ten instruments of each size, sizes 25 to 40 were used for each test. Nickel titanium instruments were significantly more flexible than stainless steel files. With regard to the torsional moment, values obtained were below the standards in all sizes except stainless steel CMU sizes 25, 35 and 40, and nickel titanium CMU size 25. Nickel titanium instrument also showed the highest angular deflection values. There were statistically significant differences between nickel titanium files and stainless steel Flexogates and between stainless steel Flexogates and stainless steel CMU. Based on these findings, the use of nickel titanium CMU and Flexogates is encouraged. Given the perceived advantages of both CMU and Flexogate instruments over conventional files for canal preparation, it would appear desirable to have the torque resistance of these instruments improved.

There are many instruments and techniques for cleaning and shaping the root canal system, but none achieves the ideal preparation, especially in curved canals. This study compared the step-back technique, using Heliapical and Flexofiles, with the Canal Master technique, using Canal Master U instruments. The Bramante method evaluated and compared the results. Final analysis showed that root canals prepared with Canal Master U instruments and technique were significantly rounder, and had less transportation than those prepared by the Heliapical and Flexofiles using the step-back technique.

The aim of this study was to evaluate the apical seal obtained using root canal filling techniques based on low and high temperature thermoplasticized gutta-percha, comparing them with the lateral condensation technique. The roots of thirty permanent upper canines and incisors were used, they were instrumented and obturated using each of the above techniques. The apical leakage was measured using a radioactive isotope and an external detection technique. No significant difference was found in the apical seal obtained by the three techniques.

The aim of the work was to evaluate the bone density of chronic periapical lesions in the area of maxillary incisors and canines. Twenty-six radiographies were made in a systematic way in patients with periapical lesions and were valued using densitometry (0-256), the grey levels by computer and the analysis program image (IBAS 2000 Kontron, Germany), taking four values in each periapical lesion from the center to the periphery within the same radiography, by using the pseudocolor to identify the four areas, always in the same coloration. Correlation was proved with significative statistically results between lower densitometric values and osteolysis and radiolucency areas.

In this article the authors make a literature review of root canal hand-instrumentation techniques in this decade. To make it possible, they also review the standardized instruments used in endodontics. They remark there are two great groups of files in use, K-type files and H-type files. In the former one there are rhombus section files and triangular section files, both more flexible than old square section files. Also in K-files group they remark the existence of files with a noncutting tip, useful for reaming techniques. In H-files group, they remark the existence of three types, typical H-files, Helifiles and S-files (including Unifiles). When studying the techniques, they remark as actual the flared techniques with anticurvature filing and step-back. New described ways of instrumentation are Crown-Down Pressureless Technique (which is said to reduce the extrusion of debris uses files with noncutting tip in reaming motion; and the Senia-Wildey technique.

Apical deformations, specially zips and elbows, during instrumentation of the root canals, are studied. The authors study why do they appear, their effect on endodontic therapy, and the way of avoiding them.

The author study in this article histopathological aspects of periapical lesions, intra-granulomatous epithelial proliferation phenomenon as pathogenic mechanism of microscopic cystic cavities formation, diagnostic problems of them all, as well as the most actual therapeutic perspectives.

A case is presented of a periapical lesion of a rather large size, which produced an important separation of two inferior incisor roots. The root canal was treated, with calcium hydroxide overextending the apex. Clinic and radiographic control after two years complete reparation of the periapex.

The time taken to achieve the sterilization of K files impregnated in a Bacillus subtilis culture was evaluated, placing the files in a glass bead sterilizer. The minimum time needed was 20 seconds at 240 degrees C and the previous cleaning of the file with a sterile wipe impregnated by alcohol reduced this time to 15 seconds.

Using a scanning electron microscope, 45 new files were examined, taken at random, of 5 different brands, of 3 different calibres and with rectangular, triangular and rhomboidal sections. Various defects were observed in the surface of all of them, such as adhered metallic fragments, burrs, deformed teeth, pores and ridges. These defects were more evident on the smaller diameter files of those studied and on those of triangular or rhomboidal section.

We have compared the microbiological activity of the following cavity liners: Life, Dycal II, Calcipulpe, Pure calcium hydroxide and Cavitec; against five different bacterial strains: Veillonella parvula, Bacteroides fragilis, Peptococcus s.p., Staphylococcus aureus, and Streptococcus beta hemolytic: The results demonstrate the higher antimicrobial activity of the manufactured cavity liners with calcium hydroxide base in comparison with the pure calcium hydroxide.