Presence of pores and vacuoles in set endodontic sealers.

AIM: To assess qualitatively the presence of pores and vacuoles in the structure of various endodontic sealers when set. METHODOLOGY: Eight specimens were prepared in keeping with Instituto Argentino de Racionalización de Materiales (IRAM) and ISO regulations for each of the 10 sealers assessed. Four specimens per sealer were examined to identify the presence of structural defects, termed pores, on the external surface. The remaining four specimens were used to examine the presence of defects on the surface exposed by cross-sectional fracture; these were termed vacuoles. The largest and smallest diameters of the pores and vacuoles were measured by scanning electron microscope on both surfaces. The structural defects were classified according to their frequency as abundant, frequent, scarce or exceptional. RESULTS: Pores and vacuoles were consistently found in every specimen of each sealer. However, their frequency and dimensions were greater in zinc-eugenol-based sealers than in epoxy-resins and glass-ionomer sealers; they increased if the sealer contained calcium hydroxide. The diameter of the pores ranged from 5 to 320 microm and the diameter of the vacuoles ranged from 80 to 500 microm. The diameter of the vacuoles always exceeded that of the pores. CONCLUSIONS: Pores and vacuoles were a consistent finding in set sealers. Their frequency and size depended on the density of the sealer and increased when the sealers contained calcium hydroxide.

Quality of apical seal in curved canals using three types of spreaders.

The aim of the present study was to evaluate the influence of spreader shape on the quality of obturation. Forty-five single canal teeth with varying degrees of apical curvature were used throughout. The canals were prepared using the step-back technique and obturated with lateral condensation. The teeth were classified into three groups (A, B, and C) and treated as follows. Group A was treated with markedly conical, flat-ended spreaders (A to D; Dentsply-Maillefer, Ballaigues, Switzerland). Group B was treated with slightly conical (15 to 40) sharp-pointed CC-cord spreaders. Group C was treated with CC-cord, slightly conical but flat-ended spreaders. The obturated teeth were decalcified in 7.5% nitric acid to obtain four cross-sections: the first at 2 mm from the apex and then the following three sections at 1-mm intervals. Section thickness was approximately 1 mm. Each section was photographed under a stereoscopic microscope. The following areas were measured on each of the microphotographs using a planimeter: (a) gutta-percha mass, (b) mass of sealer, (c) foreign bodies, and (d) empty spaces. These four areas were added to determine total cross-sectional canal area and then the percent of that area attributable to a and to b + c + d was calculated. The statistical analysis of the data (parametric Student's t test for independent groups) revealed that only in group B was the area occupied by a, the gutta-percha mass, significantly greater at all levels than the area occupied by b + c + d. Next in obturation effectiveness was group C, followed by group A.

Endodontic anatomy of the root canals of lower incisors.

Ninety lower incisors of known age (18 to 20 yr, 30 to 40 yr and over 50 yr) were grouped into 2 sets of 45 pieces each. Cross sections of the root at 4 levels (coronal, middle and apical thirds and 2 mm from the apex) were employed to study: 1. The shape of the canals 2. The changes in diameter induced by age 3. The correlation at the apex of the maximum diameter of the root canal with the Dzero diameter of endodontic instrument. The results showed that the canal anatomy of lower incisors is not as simple as it appears to be and that it is characterized by the predominance of flat shapes even in the vicinity of the foramen. The statistical analysis showed that the dentin deposits, typically age-associated, are influenced by the morphological changes that take place. A true compensation occurs between the different buccolingual and mesiodistal diameters, particularly in the vicinity of the apex, to guarantee irrigation in old age and avoid calcification fo the canal. The correlation between the maximum diameter of the canal at 2 mm from the apex and the Dzero diameter of the instruments evidenced the difficulties involved in adequate apical preparation of these teeth, regardless of age.

Endodontic anatomy of the root canals of lower incisors.

Ninety lower incisors of known age (18 to 20 yr, 30 to 40 yr and over 50 yr) were grouped into 2 sets of 45 pieces each. Cross sections of the root at 4 levels (coronal, middle and apical thirds and 2 mm from the apex) were employed to study: 1. The shape of the canals 2. The changes in diameter induced by age 3. The correlation at the apex of the maximum diameter of the root canal with the Dzero diameter of endodontic instrument. The results showed that the canal anatomy of lower incisors is not as simple as it appears to be and that it is characterized by the predominance of flat shapes even in the vicinity of the foramen. The statistical analysis showed that the dentin deposits, typically age-associated, are influenced by the morphological changes that take place. A true compensation occurs between the different buccolingual and mesiodistal diameters, particularly in the vicinity of the apex, to guarantee irrigation in old age and avoid calcification fo the canal. The correlation between the maximum diameter of the canal at 2 mm from the apex and the Dzero diameter of the instruments evidenced the difficulties involved in adequate apical preparation of these teeth, regardless of age.

Endodontic anatomy of the root canals of lower incisors

Ninety lower incisors of known age (18 to 20 yr, 30 to 40 yr and over 50 yr) were grouped into 2 sets of 45 pieces each. Cross sections of the root at 4 levels (coronal, middle and apical thirds and 2 mm from the apex) were employed to study: 1. The shape of the canals 2. The changes in diameter induced by age 3. The correlation at the apex of the maximum diameter of the root canal with the Dzero diameter of endodontic instrument. The results showed that the canal anatomy of lower incisors is not as simple as it appears to be and that it is characterized by the predominance of flat shapes even in the vicinity of the foramen. The statistical analysis showed that the dentin deposits, typically age-associated, are influenced by the morphological changes that take place. A true compensation occurs between the different buccolingual and mesiodistal diameters, particularly in the vicinity of the apex, to guarantee irrigation in old age and avoid calcification fo the canal. The correlation between the maximum diameter of the canal at 2 mm from the apex and the Dzero diameter of the instruments evidenced the difficulties involved in adequate apical preparation of these teeth, regardless of age.

Apical canal diameter in the first upper molar at various ages.

The shape of root canals cross-sectioned through their roots at 2 mm from their apices and its correlation with the D0 diameter of endodontic instruments was evaluated in 40 first upper molars. The molars were grouped according to age: under 13 yr (children), 18 to 20 yr (adolescents), 30 to 40 yr (adults), and over 50 yr. Evaluation of the root canal diameters revealed that the shapes were predominantly circular in the palatal canal, mostly flat in the mesiobuccal canal, and circular or flat in equal proportions in the distobuccal root. Age does not seem to affect the shape of the canals. Narrowing with age was statistically significant (p < 0.05) for palatal and mesiobuccal canals only. Correlation between the maximum diameter of the canals and the instruments was varied. Even in old age, diameters were observed that would require instruments of a size that would be impossible to use, because one internal diameter would exceed the root's external diameter in a different direction (i.e. intimal buccolingual diameter of #80 and external mesiodistal diameter of #70).