George G. Stewart

The importance of chemomechanical preparation of the root canal

Abstract 1. 1. The results of a clinical study to determine the importance of thorough cleansing of the root canal are reported. 2. 2. Although I do not wish to leave the impression that medication of the root canal is unimportant, for I do use medicaments (including antibiotics) where indicated, no medication other than irrigating solutions was used in this study. 3. 3. The findings indicate that the culture, although important, is not the determining factor for success or failure in therapy. 4. 4. Thorough chemomechanical cleansing of the canal is one of the most important phases of root canal therapy.

The effects of acids, alkalies, and chelating agents on dentine permeability.

Abstract The ability of eight different solutions to increase or decrease dentine permeability was evaluated in extracted human two-rooted maxillary premolars. Thirteen teeth were used in each group, making a total of 104 teeth. The Dentine Permeability Index18 was used to calculate the depth of penetration of a 2 per cent methylene blue dye into the dentinal tubules. For statistical analysis and subsequent comparisons, only ten teeth were used from each group (a total of eighty teeth). It was found that R-C Prep alternating with 5 per cent sodium hypochlorite increased dentine permeability in the apical and middle thirds of the root more than any other solution. Concentrated sulfuric acid almost eliminated dentine permeability.

Excitation of the dentinal receptor of the cat by heat and chemical agents

Abstract The electrical response evoked in a single dentinal receptor by thermal stimulation has been recorded. There was a decrease in the membrane potential of the terminal receptor membrane and trains of impulse discharges were seen when heat was applied to the surface of the canine tooth of a cat. Similar potential changes have been seen following topical application of acetylcholine to the exposed dentine overlying the receptor. The increase in depolarization of the receptor was accompanied by an increase in impulse firing frequency. The return of the membrane potential toward the resting value was associated with a reduction in impulse frequency to the resting value or below. The observations of electrical activity of the receptor were compatible with the transducer elements location in the proximal segment of a dentinal tubule or within the odontoblastic layer.

Comparison of apical leakage between Ketac Endo sealer and Grossman sealer

Forty-eight extracted human teeth were prepared for study to compare Ketac Endo cement with Grossmans cement in preventing leakage of a dye. Four groups were formed: (1) Grossmans sealer with a single gutta percha cone; (2) Grossmans sealer with lateral condensation of gutta percha; (3) Ketac Endo sealer with a single cone of gutta percha; and (4) Ketac Endo sealer with lateral condensation of gutta percha. The teeth were immersed in the dye for 10 days, after which they were rinsed in running tap water and cleared for observation. In the groups of teeth evaluated by three individual evaluators, the results consistently showed less leakage with glass ionomer sealers (groups 3 and 4) than with the Grossmans sealers (groups 1 and 2). The best results were noted when Ketac Endo sealers were used with lateral condensation.

The potential of periodontal pocket formation associated with untreated accessory root canals

Teeth that were to be extracted because of periodontic-endodontic involvement, in six patients, were treated by hemisection or root amputation. The roots were processed histologically. All cases showed the presence of accessory root canals with remnants of pulpal tissue, bacteria, and necrotic debris. It was demonstrated in the cases studied that residual necrotic tissue in untreated root canals can result in periradicular pathosis. We may speculate that if the inflammatory process persists and drainage results via the sulcus, in time, plaque and then concretions may develop.

The antihistamines and corticosteroids in the reduction of postoperative sequelae following endodontic surgery.

Abstract 1. 1. Present-day evidence indicates that inflammation following tissue injury is normal and essential to healing and repair. However, excessive amounts of inflammation following tissue injury can be injurious. Thus, control of excessive inflammation is desirable. 2. 2. The roles of histamine and the corticosteroids are discussed in their relation to inflammation. 3. 3. The encouraging results of a clinical study are here reported, showing how antihistamine compounds and corticosteroids may reduce pain, swelling, and discoloration and encourage better wound healing when used individually.

An effective penicillin-streptomycin suspension for endodontic treatment.

Abstract 1. 1. The findings of 150 infected pulpless teeth treated with a penicillin-streptomycin suspension are reported here. 2. 2. Using the culture technique as a criterion for effectiveness, the root canals of 135 of 150 infected pulpless teeth were found to be sterile after 1 or 2 treatments with the penicillin-streptomycin suspension. 3. 3. A comparison of effectiveness of the penicillin-streptomycin suspension with penicillin alone and with older root canal antiseptics is presented. 4. 4. Directions for preparing the penicillin-streptomycin suspension and the technique of using it are given.

Gaining access to calcified canals

Gaining entrance to calcified canals can be very difficult and at times impossible. With the aid of the EDTA-Urea preparation (RC-Prep, Premier Dental Products, Norristown, Pa.) and the surgical length contra-angle burs, the task can be facilitated. The use of the multipurpose probe reduces the problem of perforation. We may now be able to gain access and treat a greater number of calcified canals.

Reduced inflammatory root canal medication

Abstract Some of the presently available root canal medicaments were studied with the hope of combining and altering them so as to retain their antimicrobial activity while reducing their inflammatory potential. In the laboratory phases of the study, antimicrobial activity was measured by means of the filter-paper disk technique. The rabbit eye was used in tests for inflammatory potential. The following compounds and combinations were tested in both the laboratory and the clinic: (1) dichlorophene, (2) hexachlorophene, (3) camphorated monochlorophenol, (4) hexachlorophene plus camphorated monochlorophenol, (5) thymol 5 per cent plus camphorated monochlorophenol, in equal parts of Xylocaine ointment, plus hexachlorophene 1 per cent. The last combination seemed to have the most desirable properties of all the compounds tested. It had excellent antimicrobial activity; it was almost completely free of inflammatory potential when tested in the clinic and in the rabbits eye in the laboratory; it had excellent residual activity in the root canal; and it was easy to use.

The antimicrobial activity of four antihistamine compounds.

Abstract 1. 1. Four antihistamine compounds were tested to determine whether or not they possessed antimicrobial activity. 2. 2. The test organisms were Escherichia coli, Streptococcus faecalis , and Candida albicans . 3. 3. Perazil was tested against brain-heart infusion broth suspensions of the individual microorganisms and in sterile distilled water suspensions of mixtures of these microorganisms. 4. 4. Antistine, Benadryl, Pyribenzamine, and Perazil were tested against broth suspensions of the mixed microorganisms. 5. 5. All of the compounds tested showed antimicrobial activity against the microorganisms studied.