Evaluation Of The Risk Of A Stripping Perforation With Gates-glidden Drills: Serial Versus Crown-down Sequences

The aim of this study was to evaluatte the remaining dentine/cementum thickness using Gates-Glidden burs in serial and crown-down sequences and to observe which of the two sequences is the safest for preparing mesial roots of molars. Thirty-six left and. right human mandibular first molars were selected. Standard access cavities were made and initially explored with Flexofiles sizes 10 and 15 until the tip was visible at the apex. The teeth were embedded in a muffle speqially developed for this study using a PVC tube with two parallel metal rods An its lid. Each tooth-block was sectioned 3 mm apically to the furcation using a low-speed saw with a diamond disc. The tooth-block was examined under a microscope and an initial image was captured by a digital video system with 8 X and 12 X magnifications. Finally, the tooth-blocks were reassembled in the muffle so that the canals could be instrumented. After instrumentation the area of each mesial canal as well as the smallest distance to the root furcation were measured again. The mesio-buccal canals (crown-down order) and the mesio-lingual canals (serial sequence) presented an average area of 0.46 ± 0.16 mm2 and 0.88 ± 0.27 mm2 (P < 0.01), respectively. The mean values of the smallest distance to the furcation for the mesio-buccal and mesio-lingual canals were 0.66 ± 0.19 mm and 0.39 ± 0.13 mm (P < 0.01), respectively. The remaining dentine/cementum thickness using Gates-Glidden burs was greater in the crown-down sequence than in the serial sequence.2211824Grossman, L., A brief history of endodontics (1982) J Endod, 8 (1), p. 538Mullaney TP. Instrumentation of finely curved canals. Dent Clin North Am. l979;23(4):575-92Taintor, J.F., Use of the gates glidden bur in endodontics (1978) J Nebr Dent Assoc, 54 (3), pp. 10-12Weine, F.S., Kelly, R.E., Lio, P.J., The effect of preparation procedures on original canal shape and on apical foramen shape (1975) J Endod, 1 (8), pp. 255-262Abou-Rass, M., Frank, A.L., Glick, D.H., The anticurvature filing method to prepare the curved root canal (1980) J Am Dent Assoc, 101 (5), pp. 792-794Cunningham, C.J., Senia, S.E., A three-dimensional study of canal curvatures in the mesial roots of mandibular molars (1992) J Endod, 18 (6), pp. 294-300Coutinho-Filho.T, De-Deus G, Guimarães T, Gurgel-Filho ED, Maniglia-Ferreira C. A computer evaluation of the dentin remaining after cervical preparation in curved canals: Gatesglidden drills vs. orifice shaper. Braz J Oral Sci. 2002;1(3):116-20Lim, S.S., Stock, C.J., The risk of perforation in the curved canal: Anticurvature filing compared with the step-back technique (1987) Int Endod J, 20 (1), pp. 33-39Isom, T.L., Marshall, J.G., Baumgartner, J.C., Evaluation of root thickness in curved canals after flaring (1995) J Endod, 21 (7), pp. 368-371Gluskin, A.H., Brown, D.C., Buchanan, L.S., A reconstructed computerized tomographic comparison of Ni-Ti rotary GT files versus traditional instruments in canals shaped by novice operators (2001) Int Endod J, 34 (6), pp. 476-484Schilder, H., Cleaning and shaping the root canal (1974) Dent Clin North Am, 18 (2), pp. 269-296Bramante, C.M., Berbet, A., Borges, R.P., A methodology for evaluation of root canal instrumentation (1987) J Endod, 13 (5), pp. 243-245Bower, R.C., Furcation morphology relative to periodontal treatment. Furcation entrance architecture (1979) J Periodontol, 50 (1), pp. 23-27Kessler, J.R., Peters, D.D., Lorton, L., Comparison of the relative risk of molar root perforations using various endodontic instrumentation techniques (1983) J Endod, 9 (10), pp. 439-447McCann, J.T., Keller, D.L., LaBounty, G.L., A modification of the muffle model system to study root canal morphology (1990) J Endod, 16 (3), pp. 114-115Pilo, R., Corcino, G., Tamse, A., Residual dentin thickness in mandibular premolars prepared with hand and rotatory instruments (1998) J Endod, 24 (6), pp. 401-404Torabinejad, M., Rotstein, L., Stabholz, A., Effect of preflaring on tactile detection of the apical constriction (1995) J Endod, 21 (2), pp. 92-94West JD, Roane JB. Limpeza e modelagem do sistema de canais radiculares. In: Cohen S, Burns RC. Caminhos da polpa. 7th ed. Rio de Janeiro: Guanabara Koogan2000. p. 206-36Abou-Rass, M., Jastrab, R.J., The use of rotary instruments as auxiliary aids to root canal preparation of molars (1982) J Endod, 8 (2), pp. 78-7

Morphometric changes of Rhodnius neglectus (Hemiptera: Reduviidae): in the transition from sylvatic to laboratory conditions

In the present work, we investigated whether it is possible to detect morphometric changes in Rhodnius neglectus Lent, 1954 (a candidate vector of Chagas disease in Central Brazil) populations in the transition from sylvatic to laboratory conditions. We analyzed size and shape variation in wings of sylvatic parents and their laboratory descendents (first, third and fifth generations) using geometric morphometric techniques. Sexual size dimorphism and shape of wings were maintained, but wing size decreased from sylvatic specimens to their laboratory generations. Size variation in R. neglectus should reflect the expected morphometric changes between sylvatic and domestic populations and can be applied to analyze the level of adaptation of R. neglectus to domestic habitats. This information might be useful to detect persistent infestations in dwellings after insecticide application, or new infestations from the sylvatic environment, and is therefore important to guide vector surveillance strategies for Chagas disease