Formocresol Blood Levels in Children Receiving Dental Treatment Under GA

Resident: Swan

Article Title: Formocresol Blood Levels in Children Receiving Dental Treatment Under General Anesthesia

Authors: Kahl, et al.

Journal: Pediatric Dentistry

Volume (Number): 30 (5) Sep/Oct 08

Major Topic: Safety of Formocresol use for vital pulpotomies/risk of systemic distribution

Minor Topic: N/A

Type of Article: Scientific Article

Main Purpose: to determine the existence, if any, of formocresol in the plasma of children undergoing comprehensive oral rehabilitation involving vital pulp therapy under general anesthesia

Background: The controversy rages on regarding formocresol and its potentially harmful systemic effects when used for pulpotomies. Animal studies have demonstrated that formaldehyde and tricresol diffuse through the apical foramen within minutes. Studies using monkeys demonstrated distribution to lymph nodes, blood, kidneys, and liver. In another study, high systemic doses (500 times expected dose from 1 pulpotomy) administered IV to dogs, led to liver, kidney, and cardiac pathology.

However, there are no human studies documenting systemic distribution or pathologic tissue. And the only studies to show systemic distribution have used doses way higher than that used for a pulpotomy. There are also many natural and man made sources of formaledehyde to which humans are exposed every day. The WHO estimates the daily intake of Formaldehyde from food alone to be from 1.5 to 14 mg/day. Formaldehyde is rapidly (1-1.5 min) metabolized. The concern is that formaldehyde that escapes metabolism can form DNA-protein cross links, cause mutations and become carcinogenic.

Cresol gets little attention because it shows poor solubility and does not enter systemic circulation.

Overview of method of research: 30 2-6 year old preschoolers were enrolled, all needing expected pulpotomy treatment under general anesthesia. 50 dry cotton pellets were soaked in 2 mL of full strength Buckley’s formocresol. The average mg dose of formo per pellet was calculated (.013 mg/pellet). Each pulpotomy was performed following standard protocol. In each patient, up to 12 blood samples were drawn before, during, and after the procedure (baseline, then once every 30 minutes after the first pulpotomy until several hours after tx was completed). The blood samples were analyzed.

Findings: 85 pulpotomies were performed, 312 blood samples collected. Lower limit of quantitation (LOQ) was 14 ng/mL. (limit at which we can reasonably tell the difference between two different values). Limit of detection (LOD) was 2 ng/mL. (lowest quantity of a substance that can be distinguished from the absence of that substance) On chemical analysis, peaks of formaldehyde were seen in the 2-2.5 ng/mL range-formaldehyde was “detectable” but not quantifiable. Based on 6 adult volunteers’ samples, physiologic concentration of formaldehyde was found to be 2.6 ng/mL. In this study, formaldehyde was undetectable above that physiologic concentration. Cresol was undetectable in all samples.

Key Points/Summary: Formaldehyde and cresol are undetectable above baseline physiologic concentrations in the plasma of subjects receiving pulpotomy treatment under GA. It’s unlikely that formo used in the small doses we use poses any risks to children.

Assessment of Article: I really liked this article. While I didn’t understand all the chemistry behind it, their methods seemed to be sound and their results conclusive. It succinctly summarized the current debate over formo use and gave strong support to the fact that formo is most likely not harmful to our patients.