Efficacy of laser-based irrigant activation methods in removing debris from simulated root canal irregularities

In root canal therapy, irrigating solutions are essential to assist in debridement and disinfection, but their spread and action is often restricted by canal anatomy. Hence, activation of irrigants is suggested to improve their distribution in the canal system, increasing irrigation effectiveness. Activation can be done with lasers, termed laser-activated irrigation (LAI). The purpose of this in vitro study was to compare the efficacy of different irrigant activation methods in removing debris from simulated root canal irregularities. Twenty-five straight human canine roots were embedded in resin, split, and their canals prepared to a standardized shape. A groove was cut in the wall of each canal and filled with dentin debris. Canals were filled with sodium hypochlorite and six irrigant activation procedures were tested: conventional needle irrigation (CI), manual-dynamic irrigation with a tapered gutta percha cone (manual-dynamic irrigation (MDI)), passive ultrasonic irrigation, LAI with 2,940-nm erbium-doped yttrium aluminum garnet (Er:YAG) laser with a plain fiber tip inside the canal (Er-flat), LAI with Er:YAG laser with a conical tip held at the canal entrance (Er-PIPS), and LAI with a 980-nm diode laser moving the fiber inside the canal (diode). The amount of remaining debris in the groove was scored and compared among the groups using non-parametric tests. Conventional irrigation removed significantly less debris than all other groups. The Er:YAG with plain fiber tip was more efficient than MDI, CI, diode, and Er:YAG laser with PIPS tip in removing debris from simulated root canal irregularities

Assignments of Proton Populations in Dough and Bread Using NMR Relaxometry of Starch, Gluten, and Flour Model Systems

Starch-water, gluten-water, and flour-water model systems as well as straight-dough bread were investigated with H-1 NMR relaxometry using free induction decay and Carr-Purcell-Meiboom-Gill pulse sequences. Depending on the degree of interaction between polymers and water, different proton populations could be distinguished. The starch protons in the starch-water model gain mobility owing to amylopectin crystal melting, granule swelling, and amylose leaching, whereas water protons lose mobility due to increased interaction with starch polymers. Heating of the gluten-water sample induces no pronounced changes in proton distributions. Heating changes the proton distributions of the flour-water and starch-water models in a similar way, implying that the changes are primarily attributable to starch gelatinization. Proton distributions of the heated flour-water model system and those of fresh bread crumb are very similar. This allows identifying the different proton populations in bread on the basis of the results from the model systems.status: publishe