Prevention of the Utilization of Formaldehyde-containing Materials in Endodontics

At a recent joint symposium on Endodontics and Pediatric Dentistry, 90% of pediatric dentists and 75% of U.S. dental schools were reported as still advocating the use of formaldehyde-based products in pulp treatment. Formocresol pulpotomies and "Sargenti" paste techniques incorporating paraformaldehyde are still being popularly advocated and utilized world-wide.

Objectives: The purpose of this study was to evaluate the immunological, radioisotopic, and histological responses to the 19% concentration of formaldehyde present in the standard Buckley's Formocresol solution (BF).

Methods: 10 mongrel dogs were used. Immunologic responses were analyzed for antibody- and cell-mediated immunity. Immunization occurred via 20 pulpotomies over a 28-day period in 5 dogs. In 5 other dogs, BF pulpotomies were performed in 5 teeth/dog with C-14-labeled 19% formaldehyde. In each animal, radioactivity was measured over 1 hr, 1, 7, 14, 21, and 28 days in the blood, submandibular lymph nodes, kidney, and liver. At 28 days, the animals were killed. The teeth, bone, and surrounding tissues were processed for light microscopy by standard procedures. Semiserial 5- to 8-micron sections, stained with H&E, were examined in diffuse and polarized light. Sections were examined for acute, chronic, foreign-body inflammatory cells, extravasated erythrocytes, brown pigment, vessel, cell, and tissue destruction.

Results: (1) Pulp altered by BF 19% formaldehyde produced specific antibody- and cell-mediated responses. (2) C-14-labeled BF was detected in the blood, lymph nodes, kidney, and liver over 28 days. (3) Histopathological evaluation demonstrated tissue, cell, and vessel destruction and inflammation adjacent to the BF pulpotomies. Bone and periapical tissue damage was also present.

Conclusions: (1) Despite the removal of cresol from the Buckley's formula, untoward toxic and biologic responses occurred. (2) Paraformaldehyde-containing products should not be used in treating patients. This presentation is a tribute to the late Kaare Langeland, who died in 2008.