Variability of master gutta-percha cones.

The common technique to hermetically fill prepared root canals involves the use of "standardised" gutta-percha cones that are selected to fit the apical portion of the prepared canal space. These gutta-percha cones are manufactured to conform to a standard size and taper which should correspond to the size and taper of standard root canal instruments. Clinical observation of commercially available gutta-percha cones seemed to indicate that there is wide variation in the diameter and taper of "standardised" gutta-percha cones within the size range 25-35. The present study was undertaken to determine how closely current commercially available gutta-percha cones sizes 25, 30 and 35 conformed to the current ISO standard, and was initiated by the above clinical observation. It was not the purpose of this study to compare the results from different brands or manufacturers, but rather to establish whether commercially available gutta-percha cones collectively conformed to expected standardised sizes. One phial of cones for each of the sizes 25, 30 and 35 of eight different brands was selected for examination. The diameter of each of ten cones for each size from each brand was measured at two points, at 1 mm and at 6 mm from the tip of the cone. The results obtained for each size and each brand were tabulated and compared with ISO 6877:1995 for dental root canal obturating cones. This study demonstrated wide variability for cones from all brands, for all sizes, when individual cones of the same size were compared. While collectively the arithmetic means showed a closer correlation to the ISO Standard, irrespective of the brand size of the cone, or whether the cone was measured at 1 mm or 6 mm, many individual cones showed a great variation from the ideal. The need for less variability is discussed. It is concluded that ISO standard 6877:1995 is inappropriate- and allows for too much variation in the size of "standardised" gutta-percha cones.

Introducing the Index of Care: A web-based application supporting archaeological research into health-related care.

The Index of Care is a web-based application designed to support the recently proposed four-stage 'bioarchaeology of care' methodology for identifying and interpreting health-related care provision in prehistory. The Index offers a framework for guiding researchers in 'thinking through' the steps of a bioarchaeology of care analysis; it continuously prompts consideration of biological and archaeological evidence relevant to care provision; it operationalises key concepts such as 'disability' and 'care'; and it encourages transparency in the reasoning underlying conclusions, facilitating review. This paper describes the aims, structure and content of the Index, and provides an example of its use. The Index of Care is freely available on-line; it is currently in active development, and feedback is sought to improve its utility and usability. This is the first time in bioarchaeology that an instrument for examining behaviour as complex as caregiving has been proposed.