Radicular pulpotomy of category 3 pulps. 3. Histologic evaluation

Effect of recapitulation on accuracy of electronically determined canal length

The accuracy of an electronic apex locator to measure canal length during instrumentation when nonrecapitulated dentin debris is present has not been evaluated. The purposes of this study were (1) to compare actual with electronic canal length before and after instrumentation, and (2) to compare the accuracy of electronic length in recapitulated and nonrecapitulated canals. Actual canal lengths of 30 mature anterior teeth were determined, teeth mounted in an in vitro system, and canal lengths determined with the electronic apex locator. Canals were step-back prepared to a size 35 file. Fifteen canals were recapitulated and the other 15 were not. Canals were dried and lengths again determined with the electronic apex locator. Data showed that for electronically determined versus actual lengths: 1) 63% were longer, 23% equal, and 13% shorter before instrumentation, 2) 30% were longer, 0% equal, and 70% shorter after instrumentation, 3) instrumentation caused a mean shortening of 0.63 mm, and 4) recapitulation of nonpatent canals was necessary to obtain length reading with the electronic apex locator.

Capping of monkey pulps with Dycal and a Ca-eugenol cement

Capping of 120 teeth in four monkeys was performed with Dycal or with a calcium-eugenol cement. The observation periods were 8 days or 90 days. The monkeys were killed, and the teeth were examined histologically. After 8 days, the pulp-tissue reactions were basically the same in the two groups. The tissue adjacent to the exposure site was characterized by varying amounts of necrotic tissue, inflammatory cells, and extravasated erythrocytes. Capping material and dentin chips were displaced into the pulp tissue. Particles from the capping materials were found in vessels, macrophages, and foreign body cells. After 90 days, more hard-tissue formation occurred in the Dycal group than in the Ca-eugenol cement group. The hard tissue was formed by either fibroblasts or the original odontoblasts.

A model for experimental endodontics by transplanting human dental roots subcutaneously to rats

In 35 roots from extracted human teeth the pulp tissue was removed and the specimens autoclaved before being transplanted subcutaneously to rats. The animals were sacrificed 7, 14, 21, 90 and 140 d after transplantation and the skin and subcutaneous tissue containing the transplants were prepared for histologic examination. The human roots were well tolerated by the rats with a fibrillar connective tissue capsule surrounding the specimens. In the 90-d and 14-d groups a few root surfaces exhibited small resorption lacunae. The empty root canals became slowly occupied by a maturing granulation tissue occasionally containing foci of lymphocytes. After 140 d the canal tissue was still highly vascular with multinuclear giant cells occasionally located along the dentin walls but no internal resorption was recorded. It is concluded that this model may be useful for systematic testing of root filling materials concomitant with human studies.

Tissue reactions following apical plugging of the root canal with infected dentin chips. A histologic study in dogs' teeth

The object of the present work was to observe whether the condensation of a plug of infected dentin in the apical region, before the filling of a root canal, could show results similar to those found in the absence of contamination. The histologic analysis of the periapical tissues of dogs' teeth containing infected apical plugs showed results that were totally unfavorable, when compared to cases in which the plugs were absent. Such data do not encourage the use of dentin plugs for cases of contaminated root canals, at least until other experiments can better clarify the problem.

Tissue formation in the root canal after total pulpectomy and partial root filling

In twenty human teeth, total removal of the pulp was attempted, and the root canal was filled 2 to 4 mm. short of the foramen in the same sitting. The root filling consisted of gutta-percha points and Kloroperka N-ö as a sealer. The teeth were extracted after observation periods of 2, 6, and 10 months and committed to histologic examination. Microscopic evaluation demonstrated that after 2 months, the space in the canal between the root filling and the foramen was occupied by connective tissue slightly inflamed in the area adjacent to the root filling. After 6 and 10 months the entire space contained a fully developed cell-rich fibrous tissue, and only a few lymphocytes were observed adjacent to the root filling material.

Tissue reactions following apical plugging of the root canal with dentin chips in monkey teeth subjected to pulpectomy

The tissue reaction following apical plugging of the root canal with dentin chips in monkey teeth subjected to pulpectomy was studied. The reaction was characterized by formation of a cementum-like tissue onto the chips, often walling off the root canal as well as accessory and lateral canals. Twenty-two of twenty-four teeth were rated as successful 95 days after pulpectomy. In the control groups, in which apical plugging of the canal with dentin chips was not attempted, ten of twenty-one teeth were rated as successful at this observation time. In six of the ten successfully treated teeth in these groups a dentin chip plug had been made, although care had been taken to avoid this. It is suggested that a plug of dentin chips is well tolerated by the tissues and may present an effective barrier in the apical part of the root canal, facilitating the accomplishment of a well-condensed, tightly sealing root filling.

The apical level of root fillings

The apical level of root fillings made by general practitioners, undergraduate students and an endodontist was compared. In total, 3003 root fillings were grouped morphometrically in three classes. Class A fillings were ending at a distance from the radiographic apex. Class B fillings were ending flush with the radiographic apex or with an overfilling of not more than 1 mm, while class C consisted of fillings with a moderate (1-2 mm) or marked (greater than 2 mm) excess. For 2187 class A fillings the distance from the apical end of the root filling to the radiographic apex was measured to the nearest 0.5 mm. The 531 class B and 285 class C root fillings were given the distance 0.0 mm. A detailed classification of root fillings with regard to their length was then developed by calculating the average distances and standard deviations. A longer apex-distance was observed for root fillings made by the general practitioners than for those made by the undergraduates and the endodontist. Class B and C fillings were infrequently observed among fillings made by general practitioners. Roots from three-rooted teeth had been filled closer to the radiographic apex by the endodontist than by undergraduates. A higher relative number of class C fillings was observed for undergraduates than for the endodontist, while the opposite observation was made for class B cases.