The accuracy and sensitivity of radiographic assessments of reactive processes in dental tissues were evaluated by comparison of radiographs and histologic sections. Experimental lesions inflicted on the roots of 10 monkey incisors had been observed by means of serially obtained radiographs over a period of 315 to 370 days. The material was used for evaluation of radiographic assessment of ankylosis. For comparative purposes, assessment of the experimental lesion penetrating to the pulp and periapical radiolucency was added. True and falsely positive or negative recordings formed the basis for calculation of the accuracy and sensitivity of the radiographic assessment. The sensitivity, or the observers' ability to detect the actual changes, was high for pulp penetration, intermediate for inflammation, and low for ankylosis.

Three cases of endodontically‐induced maxillary sinusitis are presented. Two of the cases had previously been treated with overextension of gutta‐percha points. The 3rd patient had been treated endodontically approximately 15 years earlier. All patients were treated with surgical removal of the endodontic material via an intraoral approach to the sinus.

Mechanical contact with dental tissues accidentally occurs during jaw surgery. Lesions were inflicted on 10 monkey incisors during experimental surgery that simulated accidental damage to the root. In 6 teeth the lesion penetrated to the pulp. Tissue reactions were observed histologically to evaluate the long‐term iatrogenic processes induced by the procedure. The animals were killed from 315 to 370 d postoperatively. The present material illustrated 3 main categories of long‐term reactions that may be expected from mechanically produced lesions. Maintenance of pulp vitality and formation of reparative hard tissue could be observed either in association with re‐establishment of the periodontal membrane or with ankylosis; pulp necrosis was associated with periapical inflammation and resorption. The proportions of teeth with inflammation and ankylosis were not significantly different when teeth with pulp penetration were compared with teeth without penetration.