A scoring system for registration of apical periodontitis in radiographs is presented. The system is termed the periapical index (PAI) and provides an orditial scale of 5 scores ranging from 1 (healthy) to 5 (severe periodontitis with exacerbating features). Its validity is based on the use of leference radiographs of teeth with verified histological diagnoses. Results from studies involvirig 11 observers and 47 selected radiographs document that the PAI system is reasonably accurate, reproducible and able to discriminate between sub-populations. It may also allow for results from diflerent researchers to be compared. The syst(;iTi may be suitable for the analysis of periapieal radiographs in epidemiologieal studies, in clinical trials and in retrospective analyses of treatment results in endodonties.

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An apical dentine sampling technique was applied in order to monitor the bacteriology of the pulp canal and radicular dentine before and during treatment of teeth with chronic apical periodontitis. Twenty-three teeth with a radiographic diagnosis of apical periodontitis were studied. They were subjected to a standardized two-appointment treatment regimen of extensive apical reaming in the absence of antimicrobial agents and 1-week dressing with calcium hydroxide. Bacteriological samples were taken from the root canal at the start, and apical dentine samples at the end, of each sitting. Provision was made to allow growth of anaerobic bacteria. All root canals but one showed growth at the start of treatment. Dentine samples were positive in 14 of the 23 teeth at the end of the first appointment. Eight of the 23 canals had detectable growth from the canal at the start of the second appointment, but in sufficient numbers for quantification in only one root canal. The subsequent dentine samples were otherwise negative at the second appointment. There was a tendency for teeth causing symptoms to harbour more bacteria than symptomless teeth.