Lateral diffusion of single poly(ethylene oxide) chains on the surfaces of glassy and molten polymer films.

Fluorescence correlation spectroscopy was used to show that the temperature-dependent diffusion coefficient of poly(ethylene oxide) (PEO) adsorbed on polystyrene and different poly(alkyl methacrylate) (PAMA) films in aqueous solution exhibited a maximum close to (but below) the surface glass transition temperature, Tgs, of the film. This elevated diffusion was observed over a small range of temperatures below Tgs for these surfaces, and at other temperatures, the diffusion was similar to that on silicon, although the diffusion coefficient for PEO on polystyrene at temperatures above Tgs did not completely decrease to that on silicon, in contrast to the PAMA surfaces. It is concluded that the enhanced surface mobility of the films near the surface glass transition temperature induces conformational changes in the adsorbed PEO. The origin of this narrow and dramatic increase in diffusion coefficient is not clear, but it is proposed that it is caused by a coupling of a dominant capillary mode in the liquid surface layer with the polymer. Friction force microscopy experiments also demonstrate an unexpected increase in friction at the same temperature as the increase in diffusion coefficient.

Oral surgery at St. Mary's Hospital, Chapelizod. A quarter century experience of day-case oral surgery.

To mark the first quarter century of the existence of the Oral Surgery unit at St. Mary's Hospital, Chapelizod, an audit was undertaken. Twenty-nine thousand, three hundred and seventy-four (29,374) entries in the operations register were analysed, examining annual totals, categories of operation, the changing patterns of anaesthesia, including cancellations on the day, and the evolution of a true day-case service. The results showed a decline in total numbers and in some operation categories. The most striking reductions were in extractions of carious teeth and in preprosthetic surgery. The most marked increase was in surgery for impacted teeth. While general anaesthesia remains the most commonly used form of anaesthesia, there has been an increased utilisation of sedation. Since the earlier years the number of patients requiring admission post-operatively has steadily decreased but more patients have been cancelled on the day of operation. Most of the changes described reflect the influence of health care economics and the effects of fluoridation.

Migrating foreign body: a new cause of trismus.

A unique case of delayed trismus secondary to an infratemporal foreign body is presented. The pathophysiology and treatment options are discussed.