Effect of varying processing solution temperature on radiographic contrast and relative film speed of dental film.

The aim of this study was to determine the effect of a stepwise rise in temperature on three film types processed in six different processing solutions and to identify the combinations of film, solution and temperature which produced the best results in terms of radiographic contrast and relative film speed. The film types were Agfa Dentus M2, Flow X-ray and Kodak Ultra Speed while the processing solutions were Agfa, Dürr, EBX, Kolchem, MEMS and Pro-tech. An aluminium step-wedge was exposed under standardised conditions. Processing was carried out in a Dürr 245L automatic processor with variable temperature settings from 25 degrees to 35 degrees C. Unexposed films were processed at each temperature setting to determine the base plus fog values. Densitometric readings were taken using a digital densitometer, and the base plug fog values subtracted from each reading. Radiographic contrast and relative film speed were calculated and the data obtained subjected to statistical analysis using Duncan's Multiple Range Test. It could be concluded that, as the processing solution temperature rose from 25 degrees C to 35 degrees C, both radiographic contrast and relative film speed increased. The highest radiographic contrast was obtained by Agfa film in Kolchem solution at 35 degrees C, while Kodak Ultra Speed film in MEMS solution at 35 degrees C gave the highest relative film speed. An acceptable base plus fog level of 0.25 was obtained in the case of Agfa film in combination with Agfa, Dürr and Pro-tech solutions and Flow X-ray film with Dürr solutions. All the other combinations produced a base plug fog level higher than 0.25.