Study of dentinal tubule architecture of permanent upper premolars: evaluation by SEM

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.

[Radioactive isotope evaluation of apical seal of two types of thermoplasticized gutta-percha at high and low temperature]

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.

[Bone densitometry of periapical lesions]

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.

[Manual instrumentation of root canals. Review of the last decade]

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.

[Deformations occurring in the apical third of curved root canals during biomechanical preparation using manual impulsion-traction techniques]

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.

[Current perspectives on endodontic treatment of teeth with chronic periapical lesions]

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.

[Endodontic treatment of a periapical lesion causing root separation]

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 surface of various files of quadrangular, triangular and rhomboidal section using scanning electron microscopy]

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.

[Radiographic and histological study of a case of apexification in a human molar]

A case of apexification in a lower right second molar is described. Radiographs demonstrate apical closure with a different morphological pattern from that of the lower left second molar. Following extraction, after 15 months, serial histologic sections show calcified tissue obturating the apical foramen, well adapted to the initial dentin and cementum walls. Inside some small areas containing connective tissue with capillaries can be observed. The histologic and radiographic observations indicate that apical closure occurs as a result of differentiation of periodontal apical cells.

[Comparative study of the antimicrobial effect of various cavity liners used in conservative dentistry]

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.