Comparison of electrosurgery and formocresol as pulpotomy techniques in monkey primary teeth.

The purpose of this study was to compare lectrosurgery to formocresol as a pulpotomy technique and to determine the distribution of formocresol in the tooth and periapical tissues in monkeys 3-65 days post-treatment. Three groups of 20 teeth received pulpotomies using: (1) electrosurgery; (2) 14C-labeled formocresol in a zinc oxide and eugenoI base; or (3) electrosurgery followed by the uC-labeled formocresel-zinc oxide and eugenol base. The experimental groups were compared to a control group of 20 teeth which received no treatment. Since pathologic root resorption and periapical/furcal pathology were found in those teeth treated by electrosurgery with or without formocresol, the use of the electrosurgical technique used in this study does not appear to be an effective pulpo tomy procedure. The results of formocresol alone were consistent with previous research. Unlike other studies, the 14C-labeled formocresol was not observed in the periodontal ligament or surrounding bone. Concern over the use of formocresol in the pulpotomy for primary teeth (Lewis and Chestner 1981; Ranly 1984) has prompted the investigation of several alternatives to this medicament. 1 While some techniques show promise, no alternative medicament has been altogether satisfactory. Several authors, seeking to avoid the use of medicaments, have suggested electrosurgery for pulpotomies. 2 The study of this procedure has been limited, but encouraging results have been reported (Law 1957; Ruemping 1983). A major problem with the conventional formocresol pulpotomy is the potentially harmful effects which could result from formocresol movement out of the dental pulp Bimstein and Shoshan 1981; Davis et al. 1982; Fuks and Bimstein 1981; Ful<s et al. 1984; Fuks et al. 1986; Garcia-Godoy 1983; Morawa et al. 1975; Nevins et al. 1980; Wemes et al. 1982. Anderman 1967; Anderman 1976a, 1976b; George 1962; Harris 1976. into surrounding tissues and the systemic circulation? Thus, a technique that either avoids the use of formocresol or confines it to the pulp chamber is desirable. The purpose of this study was to compare histologically the effect on pulp tissue of (1) electrosurgery and (2) electrosurgery and formocresol to the well documented pulpal response to formocresol. Another purpose was to observe the distribution of formocresol in the tooth and periapical tissues. Methods and Materials Eighty teeth in 4 Macaca fascicularis monkeys with complete noncarious primary dentitions were used in this study. The animals selected were at an age at which physiologic root resorption would not be present. Three arbitrarily assigned treatment groups received pulpotomies with (1) electrosurgery; 2) l~C-labeled full-strength formocresol incorporated in a zinc oxide and eugenol base (ZOE); ° or (3) both electrosurgery and formocresol. The fourth group consisted of untreated teeth used as controls. Following intramuscular injection of ketamine, general anesthesia was induced in the animals using intravenous sodium pentobarbital. The teeth, isolated with a rubber dam, were cleansed with a solution of iodine and alcohol (1:20). The pulps were exposed through an occlusal preparation made with a #2 round bur rotating at approximately 50,000 r/min. Normal saline was used as both an irrigant and coolant during the preparations. The pulp chamber roof was removed with the round bur after all debris was rinsed from the teeth. For the first group, pulp tissue was removed using an electrosectioning machine b at a setting of 3.5. Short ̄ Caulk Temporary Cement -LD Caulk Co; Milford, DE. ~Block et al. 1977; Block et al. 1978a, 1978b; Block et al. 1983; Dflley and Courts 1981; Fulton and Ranly 1979; Mishida et al. 1971; Myers et al. 1978; Myers et al. 1983; Pashley et al. 1980. PF.D~A~R~C Dvacns’rRv: SEgr~aE~1987/VoL. 9 No. 3 189 strokes were used to remove the pulpal tissue to the level of the canal orifice. Coagulation current at a setting of 4.5 was used at the amputation site. If hemorrhage was not controlled immediately then current was reapplied. Debris was removed from the chamber with a sterile cotton pledget. A piece of .001-inch gold foil was placed carefully on the pulpal floor to act as an inert layer between the pulp stumps and subsequent dressings. A ZOE base was placed over the foil with amalgam alloy condensed over the base. The second group of teeth had pulps removed with electrosurgery as previously outlined. In addition, a creamy mixture of formocresol, containing one drop of 14C-labeled formalin,cand ZOE was placed over the canal orificeinstead of gold foil. Amalgam then was condensed over this base. In a third group, the coronal pulp was removed with a round bur and hemorrhage was controlled with pressure from moist sterile cotton. A creamy mixture of labeled formocresol-ZOE base as used in the previous group was applied to the canal orifices and amalgam then was condensed over this base. Following intramuscular injection of ketamine, general anesthesia was induced using intravenous sodium pentobarbital. The four animals were sacrificed by perfusion with 5% formolsaline, as described by Bell (1969), at 3, 14, 41, and 65 days post-treatment. The head was removed and placed in 5% formolsaline for 8 hr. Following fixation, the maxilla and mandible were dissected from the head and periapical radiographs were taken of all teeth. After decalcification in 10% formolcitrate, the jaws were sectioned into blocks, each containing a tooth with its alveolus. All metals were dissected carefully from the teeth. The teeth were embedded in paraffin and 5-~ sections were made of each canal and furcation area of the teeth. Representative slides were dipped in autoradiographic emulsiond and developed as described by Prescott (1964). All slides were stained with H&E.