Kaare Langeland

Biologic effects of dental materials: 3. Toxicity and antimicrobial effect of endodontic antiseptics in vitro

Abstract A number of commonly used endodontic antimicrobial agents were evaluated for cytotoxicity and bactericidal effect by an objective method. It was found that all medicaments were markedly toxic compared to their antimicrobial effect. On the basis of a balance between the cytotoxicity, the antimicrobial effect, and the specific needs, a recommendation for an adequate irrigation solution and a medicament for dressing is made.

Biologic effects of dental materials

Abstract Twelve different root canal filling materials were tested regarding cytotoxicity in vitro with a new method which allowed complete material-cell contact throughout the entire setting time. Quantitation of toxicity was possible. All materials tested were highly toxic when freshly prepared, although an experimental cement was remarkably less toxic than other materials. Chloropercha, after chloroform evaporation , had the lowest toxic effect of all set materials. A correlation of in vitro and in vivo methods for evaluation of root canal filling materials was made.

Root canal dentinal tubule disinfection

Dentinal tubules of the root canal walls of human teeth were infected in vitro with a known bacterial isolate. The roots were exposed to either calcium hydroxide or iodine potassium-iodide for various periods of time and the viability of microorganisms was determined by incubation of entire root samples in a culture medium. The effects of the two agents on microbial viability were evaluated and compared. Iodine potassium-iodide disinfected dentin effectively. In contrast, bacteria remained viable in the dentin after relatively extended periods of calcium hydroxide treatment.

Periodontal disease, bacteria, and pulpal histopathology

Abstract Sixty teeth with various degrees of periodontal disease were extracted and studied histologically in order to determine the effect of periodontal disease on the pulp. Pathologic changes occurred in the pulp tissue when periodontal disease was present, but the pulp did not succumb as long as the main canal—the major pathway of circulation—was not involved. The cumulative effect of periodontal disease on the pulp was manifested by pulpal inflammation, calcifications, apposition of calcified tissue, and resorption. Pulpal inflammation from involved lateral canals or root caries will damage the pulp, but total disintegration apparently occurs only when all main apical foramina are involved by bacterial plaque.

A histopathologic and histobacteriologic study of 35 periapical endodontic surgical specimens

Biopsy specimens were obtained, during endodontic surgical procedures performed on 35 patients. Histopathologic and histo bacteriologic studies of the specimens showed that there was no correlation between the presence of various inflammatory cells and the clinical signs and symptoms of the patients. Epithelium was found in 21 specimens, but only nine lesions were diagnosed as cysts. Although bacteria were found in five specimens, in only one case were the bacteria located in the disintegrating tissue of the root canal and periapical tissue.

Clinical, radiographic, and histologic study of endodontic treatment failures

One hundred fifty cases of endodontic treatment failures were studied clinically, radiographically, and histologically. Fifty-seven percent of the teeth were asymptomatic. Pain alone and/or associated with swelling was present in 21% of the teeth. There was no correlation between the size of periradicular rarefaction and the occurrence or severity of clinical signs and/or symptoms. Stainable bacteria were demonstrated in 69% of the teeth and were present mostly in the canal. The severity of periradicular inflammation was related to presence of stainable bacteria in the canal. Swelling and pain or a draining sinus tract was often associated with stainable bacteria inside the canal. The development of a radicular cyst associated with an endodontically treated tooth that has failed is not necessarily the cause of endodontic treatment failure.

A histopathologic, histobacteriologic, and radiographic study of periapical endodontic surgical specimens

Data available on 230 periapical endodontic surgical specimens were studied. It was found that bacteria occurred in the periapical tissue very infrequently. In addition, there was no correlation between the presence of acute inflammatory cells and the presence or absence of pain. Granulomas with epithelium occurred in 61 out of 230 cases, while 14 of these were cysts. Of the 110 cases with radiographic follow-up data, 67 were classified as successful, 40 were uncertain, and 3 were unsuccessful according to a modification of Strindbergs criteria, whereas 107 would have been successes according to the criteria of Bender and Seltzer and their associates. No valid biologic or clinical basis for endodontic therapy as suggested by Bhaskar was found in this material.

Human pulp changes of iatrogenic origin

Abstract The iatrogenic changes which result from cavity preparation, and the use of medicaments and materials in restorative general dentistry have a tendency to accumulate and leave a chronic inflammation in the pulp. The practical importance of this can be appreciated only in the long run. Advocates of a material or a method often base their evaluation of success on lack of immediate pain or on the fact that the treated tooth has not broken down within a year or two. It is evident, however, that a chronic inflammation may continue for years without any clinical symptoms. Lack of symptoms is no criterion of the success of a method or material. Our patients and our society are not well served unless the dental profession considers the possibility of iatrogenic changes in all procedures and avoids the use of methods that will cause pathologic changes.

A comparison of antimicrobial effects of calcium hydroxide and lodine-potassium iodide

The purpose of this study was to compare the antimicrobial effects of calcium hydroxide with that of iodine-potassium iodide. Cultures taken from human root canals after the completion of canal preparation and before obturation were incubated and read periodically. The effects of calcium hydroxide or iodine-potassium iodide, used as an intracanal agent on culture results, were statistically analyzed. Less culture reversals occurred when calcium hydroxide was used. From evidence presented in this paper, we concluded that calcium hydroxide should be given consideration for routine use as an intracanal agent in endodontics.

Effect of Attrition on Subjacent Dentin and Pulp

Deciduous and permanent teeth from swine, monkeys, and humans, with dentin exposed by attrition, were studied histologically. Bacteria were present in exposed dentinal tubules, in cracks in dentin, and in necrotic pulp tissue. Remaining primary dentin and secondarily formed irritation dentin did not seem to protect the pulp entirely from exogenous irritants, and microscopic changes were observed in the pulp.