Keywords: dye dilution technique; dyes; filtration. IntroductionMicroorganisms present inside root canals may remain active in the dentinal tubules even after vigorous chemicalmechanical preparation. Thus, perfect apical sealing is desirable to prevent the remaining bacteria and their endotoxins from reaching the root apex (1,2). Apical leakage is considered to be a common cause for endodontic therapy failure, and is influenced by many variables such as different filling techniques, the physical and chemical properties of sealers and the presence or absence of a smear layer (1,3). In coronal leakage, the canal may be recontaminated in various ways such as contact between the oral bacterial flora and root canal tubule inlets. However, it most frequently occurs as a result of loss of temporary filling, or inadequate endodontic filling or crown sealing (4,5).According to Timpawat et al. (6), endodontic sealers are used to eliminate the interface between the gutta-percha and the dentinal walls. Leakage may, however, occur at the interfaces between the sealer and dentin, sealer and gutta-percha and in spaces within the sealer itself. Thus, the quality of the filling depends largely on the sealing capacity offered by sealers (7,8).Methodologies in vitro are used to estimate sealing quality, generally by measuring microleakage that allows the tracer agent to penetrate the filled canal. Commonly used tracers are dyes, radioisotopes, bacteria and their products, such as endotoxins. Bacteria used as tracers most closely approximate what happens clinically in terms of leakage (9-11). Other methodologies, such as fluid filtration and dye extraction methods have also been used, their main advantage being high reproducibility (1,(12)(13)(14).The aim of this review was to critically analyze the various methodologies reported in the literature for assessing root canal sealing capacity. Apparently, they are not standardized, which makes it difficult to compare the results obtained when different methodologies are used, even though the same substrate is being assessed. Literature ReviewAlthough there are many leakage studies, there is no consensus about the endodontic sealer and core material sealing capacities. One of the reasons is that investigations do not use a standardized methodology and this frequently

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The aim of this study was to evaluate the bone regenerative effect of glutaraldehyde (GA) cross-linking on mineralized polyanionic collagen membranes in critical-sized defects on rat calvarias. Bone calvarial defects were induced in Wistar rats, which were then divided into five groups: a sham group; a control group, which received a commercial membrane; and GA, 25GA, and 75GA groups, which received one of three different polyanionic collagen membranes mineralized by 0, 25, or 75 hydroxyapatite cycles and then cross-linked by GA. Bone formation was evaluated based on digital radiography and computerized tomography. Histological analyses were performed 4 and 12 weeks after the surgical procedure to observe bone formation, membrane resorption, and fibrous tissue surrounding the membranes. Measurement of myeloperoxidase activity, tumor necrosis factor alpha, and interleukin 1beta production was performed 24 h after surgery. The percentage of new bone formation in the GA, 25GA, and 75GA groups was higher compared with the control and sham groups. In the GA and 25 GA groups, the membranes were still in place and were contained in a thick fibrous capsule after 12 weeks. No significant difference was found among the groups regarding myeloperoxidase activity and interleukin 1beta levels, although the GA, 25GA, and 75GA groups presented decreased levels of tumor necrosis factor alpha compared with the control group. These new GA cross-linked membranes accelerated bone healing of the calvarium defects and did not induce inflammation. In addition, unlike the control membrane, the experimental membranes were not absorbed during the analyzed period, so they may offer advantages in large bone defects where prolonged membrane barrier functions are desirable.

It was concluded that the use of dental floss impregnated with 5% chlorhexidine gluconate resulted in additional reductions in the supragingival biofilm relative to the results achieved with conventional waxed floss on the anterior teeth of a well-motivated and well-instructed population.