Systemic absorption of 14C-glutaraldehyde from glutaraldehyde-treated pulpotomy sites.

The purpose of this research was to measure the. systemic absorption and distribution of glutaraldehyde from pulpotomy sites in dogs. Pulpotomies were performed on the incisors and canines of 5 mongrel dogs. A cotton pellet containing 20 ~1 of 2.5% "4C-(1,5) glutaraldehyde with an activity 6.25 x 105 dpm/~l was placed in each pulpotomy site for 5 rain. Whole blood samples, urine, and expired air were collected up to 90 rain when the animals were sacrificed and tissue samples removed from various organs. The tissue samples were prepared and counted in a scintillation counter to determine 14C-activity. The results demonstrate that glutaraldehyde is absorbed into the systemic circulation following 5-rain application of the agent to vital pulpotomy sites. Tissue binding of absorbed glutaraldehyde was relatively low and the remaining portion of the absorbed glutaraldehyde was metabolized and excreted in the urine or exhaled as carbon dioxide. Gradual impairment of the microcirculation of the pulp occurred following glutaraldehyde application. The need for an alternative to formocresol as a pulpotomy agent in primary teeth arises from concern about formocresol’s clinical effectiveness, 1-3 local effects, 4-6 systemic absorption, 7,8 and systemic toxicity. 9,1° Glutaraldehyde has been suggested as a potential pulpotomy agent. ~1,~2 Glutaraldehyde is a bifunctional reagent and is a standard fixative for electron microscopy.~3 It is an effective protein crosslinking agent and therefore a powerful tissue fixative. ~4-~7 In viv&8 and in vitro studies ~9 report glutaraldehyde diffuses through tooth structure less readily than does formocresol. Glutaraldehyde also has been shown to diffuse readily from zinc oxideeugenol cement. 2° Animal studies suggest glutaraldehyde is more active in fixing surface pulp tissue and diffuses less readily through the pulp than does formocresol. 12 Although limited investigations report favorable clinical results, 2L22 so little information is available concerning glutaraldehyde as a pulpotomy agent in humans that it is currently impossible to assess its effectiveness. In view of these concerns relating to formocresol and the need to evaluate alternative pulpotomy agents, this study was undertaken to investigate the systemic absorption of glutaraldehyde from vital pulpotomy sites. Methods and Materials Dogs weighing 20-25 kg were anesthetized with pentobarbital sodium (30 mg/kg). Polyethylene catheters were placed in the femoral artery for collecting blood samples and in the femoral vein for the infusion of 5% mannitol to facilitate urine collections. A Foley catheter ~ was placed in the bladder for collection of timed urine samples. A cuffed endotracheal tube b (10 mm ID) was placed and connected via one-way expirating valve to a heavy-walled, 120-liter bag for the collection of all expired air. Pulpotomies were performed on the 16 maxillary and mandibular anterior teeth of each animal. Pulpal hemostasis was obtained with cotton pellets and control samples of blood, urine, and expired air were obtained. One cotton pellet containing 20~1 of 2.5% ~4C-(1,5) glutarala 12 French -Inmed Corp: Norcross, GA. b Curity -The Kendall Co: Boston, MA. 134 14C-GLUTARALDEHYDE ABSORPTION: Myers el al. dehyde with an activity of 6.25 x IO dm/uJ was placed in each pulpotomy site (specific activity 2.28 mCi/mole). Concetrated stock solutions of glutaraldehyde may contain a variety of molecules other than the glutaraldehyde monomer, and buffered dilute solutions should be kept in cold storage. The Cglutaraldehyde (5.0%) was diluted just before use with an equal volume of 50 mM phosphate buffer to bring the pH to 7.4 on the day of the experiment. C is a radioactive tracer used for identification and quantification of the glutaraldehyde absorption and metabolism. After 5 min the cotton pellets were removed. Whole blood samples were collected at 15-min intervals through 90 min. Urine collections were made at 0-30, 30-60, and 60-90 min. Expired air was bubbled slowly through 2 carbon dioxide traps connected in series, each containing 50 cc of Hyamine hydroxide. Aliquots of these traps were counted in a liquid scintillation counter. The animals were sacrificed and tissue samples removed from the liver, kidney, lung, heart, and diaphragm. Bile samples also were collected. These samples were weighed, homogenized in a Polytron at a tissue-to-water ratio of 1:1. Aliquots of the homogenate were placed in liquid scintillation vials and decolorized with 30% H2O2 prior to liquid scintillation counting. All samples were counted repeatedly until stable counts were obtained. At least 10,000 counts were collected for each sample. Quench corrections were made using external standards and the data expressed as dpm. Plasma samples were acidified and purged with N2 to remove all traces of CO2. In separate experiments, several dogs received pulpotomy treatments consisting of saline, undiluted formocresol, 2.5% nonradioactive glutaraldehyde (pH 7.4) or 50% nonradioactive glutaraldehyde (pH 3.5). Five minutes later the cotton pellets containing the various treatment agents were removed and replaced with cotton pellets containing 20 u,l of I at pH 7.4 at an activity of 1.5 x IO cpm/u,l (1 mM). The time course of the appearance of I in plasma was quantitated, as was the volume of distribution of iodide, to permit quantitation of total I absorption from each pulpotomy site. This was done to evaluate the functional properties of local pulpal circulation beneath the pulpotomy treatment. Autoradiographic specimens were prepared to grossly localize the C-glutaraldehyde within the tooth and surrounding tissue. The anterior portion of the mandible was removed from 2 dogs with a high-speed handpiece. The sections were embedded in methyl c Custom synthesis — New England Nuclear: Boston, MA. d Model LS 3801 — Beckman Instruments: Irving, CA. • Brinkman Instruments: Westbury, NY. ' Gillings-Hamco-Bronwill Scientific Co: Rochester, NY. methacrylate and sectioned with a thin sectioning machine into 150 u,m-thick horizontal and cross sections. These sections were placed between 2 pieces of dental x-ray film in a cassette. Two weeks later the film was processed to localize the C-activity.