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The objective of this study was to evaluate the fracture risk of ProTaper nickel-titanium (NiTi) rotary instruments under a continuous versus an alternating rotation when using the same instrumentation sequence. Plastic blocks with an embedded artificial root canal were used to investigate the fracture risk of NiTi instruments under a continuous rotation (360 degrees) and an alternating rotation (clockwise 60 degrees and counter-clockwise 45 degrees). A new instrument set was used until fracture of any instrument occurred. The number of times an instrument set and instrument type were used before fracture occurred was recorded and statistically evaluated. The results obtained in this investigation showed that the fracture risk of ProTaper instruments when used under continuous rotation was significantly higher (52.14% / P<0.001) compared with use under an alternating rotation. [ABSTRACT FROM AUTHOR]

Aim To determine the knowledge of undergraduate Spanish dental students regarding the indications of systemic antibiotics in the management of endodontic infections. Methodology The final year dental students from four Spanish dental schools were requested to answer a one-page questionnaire on the indications for systemic antibiotics in the treatment of endodontic infections. One hundred and seventy-five students were asked to participate in this research. Data were analysed using descriptive statistics and chi-square test. Results One hundred and four students (93.7%) completed satisfactorily the survey and were included in the study. The average duration of antibiotic therapy was 7.0 ± 2.0 days. All respondents chose amoxicillin as the first-choice antibiotic in patients with no medical allergies, alone (47%) or associated with clavulanic acid (53%). The first drug of choice for patients with an allergy to penicillin was clindamycin 300 mg (99%). For cases of irreversible pulpitis, up to 63% of students would prescribe antibiotics. For the scenario of a necrotic pulp, symptomatic apical periodontitis and no swelling, 44% would prescribe antibiotics. Almost 40% of students would prescribe antibiotics for necrotic pulps with asymptomatic apical periodontitis and a sinus tract. Conclusions It is necessary for the Spanish schools of dentistry to improve students' knowledge about antibiotics and their indications in endodontics. Interactive education analysing real endodontic cases using problem-based learning would help students acquire better skills in prescribing antibiotics in pulp-periapical pathosis. [ABSTRACT FROM AUTHOR]

The difficulty of eliminating Enterococcus faecalis and other bacteria infecting dental root canals makes it desirable to develop formulations capable of sustained release of antibiotics within the canal. With this function in view, in this work we compared the mechanical, drug release and biocompatibility properties of amoxicillin-loaded collagen (CL) and CL complexed with poly[(methyl vinyl ether)-co-(maleic anhydride)] (PVMMA), with or without glutaraldehyde (GTA) or the natural product genipin (GN) as cross-linker. Collagen was not denatured by complexation with PVMMA. Only CL-PVMMA-GN sponges did not disintegrate during 7 days exposure to cell culture medium (un-cross-linked CL disintegrated within 24 h and un-cross-linked CL-PVMMA within 4 days), and CL-PVMMA-GN sponges also exhibited the most appropriate combination of mechanical properties (hardness, modulus of deformability and plasticity). CL-PVMMA-GN sponges absorbed aqueous medium faster than other cross-linked formulations, but their maximum uptake was less; and drug release from CL-PVMMA-GN sponges tended to be faster than from any other, except un-cross-linked CL-PVMMA, maximum release taking about 4 days. No formulation significantly altered the viability of L929 fibroblast-like mouse connective tissue cells, but cells growing on sponges showed signs of non-adherence. It is concluded that genipin-cross-linked CL-PVMMA sponges merit further investigation as antibiotics vehicles and aids to tissue regeneration in the dental root canal. [ABSTRACT FROM AUTHOR]