Formocresol and Calcium Hydroxide Therapy

¹ Departments of Oral Diagnosis and Pedodontics, Indiana University School of Dentistry, Indianapolis, Indiana

Clinical procedures recommended for the management of cariously exposed human primary and young permanent pulps were performed on the teeth of rhesus monkeys to observe the responses of the pulps and periapical tissues to formocresol and calcium hydroxide pulp-dressing materials.

The original sample consisted of 36 primary and 12 young first permanent molars in 3 monkeys approximately 20 months old. The coronal pulp tissues were amputated and pulp-dressing materials were placed over the radicular pulp stumps of 46 teeth. These teeth represented specimens in a 17-286-day postoperative range. Two maxillary [see figure in the PDF file] first permanent molars were untreated. The untreated and treated teeth were examined microscopically, and pulp and periapical tissues were compared.

Twenty-one teeth were treated with formocresol, and 15 of these were observed to be "fixed" to an apical half or third depth. Twenty teeth contained vital tissue in the apical third, half, or greater portion of the [see figure in the PDF file] canals. One tooth was not available for study and was considered a failure. Dentin chips obstructing the annals of 5 teeth apparently prevented pulpal fixation.

Three pulps treated with formocresol revealed fixed pyknotic leucocytes dispersed among an excess of dentin chips blocking the root-canal entrances, and two pulps were observed to have leucocytes in the apical area. One of these 2 pulps was necrotic in the remaining portion of the canal, and the othet pulp revealed a peculiar syncytiunm in the apical third of the canal in which scattered inflammatory cells were observed. Successful treatment was at a 70 per cent level.

Fifteen of 25 teeth treated with calcium. hydroxide presented normal non-inflamed tissue. Ten teeth had inflamed or necrotic pulp tissues, and the range of inflammation was judged to be from mild to severe. Sixty per cent of these 25 teeth was determined to have been successfully treated. Complete calcific repair wxas noted in 1 of 25 teeth, whereas 19 teeth were incomplete. Seven of 10 teeth with inflamed pulps also presented incomplete calcific repair. Five teeth contained no calcific repair, and 3 of these had inflamed pulps. Osteodentin was present in the canals of 6 primary teeth (3 formocresol and 3 calcium hydroxide). With one exception, normal non-inflamed tissue was noted in these teeth indicating a persisting vitality.

No apparent differences were noted when comparing the effects of the pulp-dressing materials on the primary and the permanent teeth, with the exception of osteodentin, which was observed in the primary teeth treated with both pulp-dressing materials.

There were no noticeable effects of the pulp-dressing materials on the periapical tissues.

The results of this study give the impression that the formocresol pulp therapy is superior to the calcium hydroxide pulp therapy for primary teeth.