Comparative study of the configuration and the cleanliness level of root canals prepared with the aid of sodium hypochlorite and bis-dequalinium-acetate solutions

Bis-dequalinium acetate (BDA), a quaternary ammonium compound, was introduced as a bactericidal and chemotherapeutic agent for endodontic use. This study was undertaken to compare the efficacy of this compound to 5.25% sodium hypochlorite in the cleansing and shaping of root canals. One hundred twenty freshly extracted teeth were divided into three groups. Each group was treated with the aid of the test material; saline solution was used as a control. After completion of the endodontic preparation, a silicone imprint of the canals was performed and the teeth were decalcified. The imprints were examined three-dimensionally to determine the amount of debris and canal configuration due to defective preparation and anatomic variation. No significant difference could be observed between the tested materials with respect to cleanliness and the shape of the canals. At the apical third, however, the BDA-treated canals showed more favorable results with respect to cleanliness. On the basis of the present and previous findings, it was concluded that BDA might be a favorable replacement for sodium hypochlorite as an irrigation solution.     

Glycylprolyl dipeptidylaminopeptidase from Bacteroides gingivalis

Dipeptidyl aminopeptidase activity was found in the culture medium of Bacteroides gingivalis 381. The enzyme, hydrolyzing glycylprolyl-4-methylcoumaryl-7-amide, was purified 750-fold from culture medium by ammonium sulfate precipitation, Sephadex G-200 gel filtration, and DEAE Bio Gel A column chromatography. The molecular weight, determined by gel filtration, was approximately 160,000. The isoelectric point of the enzyme, estimated by isoelectric focusing using polyacrylamide disk gel electrophoresis, was about pH 6.2. The optimum pH of the enzyme was about 8.0, and the Km value was 0.05 mM. The enzyme activity was strongly inhibited by phenylmethylsulfonylfluoride and diisopropylfluorophosphate. The purified enzyme specifically cleaved glycylprolyl dipeptide from partially digested type I collagen.     

An in vitro investigation of peak insertion torque values of six commercially available mini-implants

This study compared peak insertion torque values of six commercially available self-drilling mini-implants [Mini Spider? screw (1.5 × 8 mm), Infinitas? (1.5 × 9 mm), Vector TAS? (1.4 × 8 mm), Dual Top? (1.6 × 8 mm), Tomas Pin? (1.6 × 8 mm), and Ortho-Easy? (1.7 × 6, 8, and 10 mm)]. Twenty implants each were drilled into acrylic rods at a speed of 8 rpm using a motorized torque measurement stand, and the values were recorded in Newton centimetres (Ncm). A further 20 Ortho-Easy? implants with a length of 6 and 10 mm were tested at 8 rpm; 20 implants of 6 mm length were also tested at 4 rpm. Kaplan-Meier estimates of the peak torque values were compared using the log-rank test with multiple comparisons evaluated by Sidak's test. There were significant differences in the maximum torque values for different mini-implants with the same length. The Mini Spider? screw and Infinitas? showed the lowest average torque values (6.5 and 12.4 Ncm) compared with Vector TAS?, Dual ToP?, Tomas Pin?, and Ortho-Easy? (30.9, 29.4, 25.4, and 24.8 Ncm, respectively). There was no correlation between the diameter of the implants and torque values. The Tomas Pin? showed the largest standard deviation (7.7 Ncm) and the Dual Top? implant the smallest (0.6 Ncm). Different insertion speeds did not result in significant differences in peak torque values but the 6 mm mini-implants showed significantly higher torque values than the 8 and 10 mm implants. Using a 'torque limiting' screwdriver or pre-drilling cortical bone to reduce insertion, torque appears justified for some of the tested implants.