Some effects of Ledermix® paste and Pulpdent® paste on mouse fibroblasts and on bacteria in vitro Taylor MA, Hume WR, Heithersay GS. Some effects of Leder- mix® paste and Pulpdent® paste on mouse fibroblasts and on bacteria in vitro. Endod Dent Traumatol 1989; 5: 266-273. Abstract - Dilutions of Ledermix® paste, Pulpdent® paste and a mixture of equal parts by weight of Ledermix paste and Pulp- dent paste were added to in vitro cultures of mouse fibroblasts or baeteria for 24 h, and various cell functions were then examined: mitosis in and survival of fibroblasts, and survival oi Laclobacillus casei or Streptococcus mutans. Ledermix was found to reversibly inhibit mitosis while present in the concentrations range 10"^ to 10~^ mg/ml. Mixing with Pulpdent did not modify this antimitotic effect. Ledermix killed mouse fibroblasts at 10"^ mg/ml and above, while Pulpdent killed at 1 mg/ml and above. The toxic effect of Ledermix was slightly inhibited by mixing it with Pulp- dent. Ledermix killed S. mutans at about the same concentration at which it killed the mammalian cells, but required a one thousand-fold greater concentration to kill L. casei. Pulpdent killed both L. casei and S. mutans at approximately one-fifth of the concentration at which it killed the mammalian eells. Pulpdent slightly potentiated the antibacterial effect of Ledermix. The pH of Pulpdent was reduced by approximately 0.3 units by mixing with Ledermix. The present data showed that the 50:50 mix of Ledermix and Pulpdent retained the properties examined that are thought to be of therapeutic benefit, while not increasing the toxicity of the component parts to mammalian cells. Mark Anthony Taylor\ Wyatt Roderic Hume^ Geoffrey Sinclair Heitiiersay^ School of Dentistry, 'University of Adelaide, Adelaide and ''Wesfmead Hospifal Dental Clinical School, Sydney, Australia Key words: fibroblasts: cellular effecfs; bacteria. Professor W R. Hume, University of Sydney, Westmead Hospital Dental Clinical School, Westmead 2145, Australia. Accepted for publication April 17,1989. Apical periodontitis is caused by bacteria located within the tooth root (1-4). In general, endodontic treatment aims to eliminate these bacteria and their toxic products from the root canal. Complete de- bridement and bacterial decontamination of the root is thought to be a precondition for successful repair of the apieal tissues (5). Bacterial ehmination is usually achieved by a combination of chemomechanical de- bridement and antibacterial medication. Fastidious debridement has been shown to significantly reduce the number of bacteria, but some remain and are able to grow rapidly between treatments if an antibac- terial dressing is not used (6-8). Aqueous calcium hydroxide paste placed for one month eradicated re- sidual intracanal bacteria (9). Post-treatment pain and swelling is a significant clinical problem. Such symptoms were noted follow- ing chemomechanical debridement of asymptoma- 266 tic teeth with apical periodontitis in 18% of 50 cases treated, while pain alone occurred in another 6% (10). Several investigators (11-14) have reported that corticosteroids reduce the incidence of" post- treatment pain, presumably because of their anti- inflammatory effects. Two independent reports give strong indications that a corticosteroid-antibiotic preparation (Ledermix® paste, Lederle Pharmaceu- ticals, Cyanamid GMBH, Wolfratshausen, FRG) in chemomechanically debrided root canals may reduce the incidence of post-treatment pain and swelling (17, 18). In the endodontic treatment of apical perio- dontitis it has been suggested that a combined Le- dermix paste/calcium hydroxide dressing that in- cludes equal quantities of Ledermix paste and Pulp- dent® Paste (Calcium hydroxide in aqueous methylcellulose; Pulpdent Corp. of America, Brook-