Development of predictable periapical lesion monitored by subtraction radiography

Abstract

Forty‐eight teeth of two baboons were used to establish a methodology for the development of predictable periapical lesions. The canines and third molars were used as controls. All pre‐ and post‐operative radiographs were taken using modified Precision® X‐ray beam guiding to maintain exposure geometry. After routine endodontic access preparation, the pulps were damaged 3–4 mm short of the apex, dental plaque was introduced and mixed with pulp debris, and the access opening was closed with amalgam. Control radiographs were taken at 7‐day intervals. Ten experimental and two control teeth were used for each observation period of 1, 4, 8, and 20 weeks. The radiographs were analyzed using computerized temporal subtraction. After the animals were killed, the specimens were processed for histologic examination. In all cases, pulpal necrosis and bacteria were present in the root canal, and in the periapical area adjacent to necrotic tissue. The periapical lesions had a mixture of inflammatory cells, with predominance of plasma cells, lymphocytes and multinucleated cells. Racliographic analysis by subtraction radiography showed hard tissue changes as early as 7 days. The method predictably developed periapical lesions, which could be monitored by subtraction radiography, and there was a correlation established between radiographic and histologic findings.

Radiological aspects of apical periodontitis

“…When the animals had been immunized against the infecting microbes, the lesions were more clearly circumscribed with a condensed demarcation against the surrounding bone, while non‐immunized monkeys had lesions that were diffuse and usually more extended. In baboons, subtraction radiography has been reported to allow identification of changes in the bone architecture as early as 7 days after infection of the pulp (42). In sealed infected teeth, inducing periapical pathosis, minor radiographic changes were seen at 2 months, becoming more visible after that time (43).…”

Materials used for root canal obturation: technical, biological and clinical testing

“…In addition, partly to overcome the practical obstacles associated with the frequently long time required for complete restoration of periapical tissues, categorization into ‘healed’, ‘healing’ and ‘persistent disease’ has been proposed (62). Attempts have also been made to apply automated procedures on digitized images (80–82), and treatment procedures, if not materials, have been assessed with such methodology (83).…”

Periapical radiolucencies as evaluated by bisecting-angle and paralleling radiographic techniques

“…There is no indication that this technique provides a better validity than conventional radiographic examination in diagnosing caries but it seems to be useful for detection of small substance loss in the marginal periodontium (Kullendorf et al 1992, Wenzel et al 1992. Promising results have also been obtained for diagnosing alteration in the apical periodontium (Pascon et al 1987, Kullendorf et al 1988). Because of the difficulties in determining the size of periapical lesions with conventional radiographic techniques it is possible that digital subtraction radiography in the future will be a valuable complement in follow-up controls after endodontic treatment and apical surgery.…”