Gunnar Hasselgren

Effects of calcium hydroxide and sodium hypochlorite on the dissolution of necrotic porcine muscle tissue

The dissolving effect of the endodontic medicamentscalcium hydroxide (Ca(OH) 2 ) and sodium hypochlorite (NaOCI) on necrotic tissue was studied. Pieces of necrotic porcine muscular tissue were placed in either a 0.5% NaOCI solution (Dakins solution), Ca(OH) 2 , mixed with water, or a NaOCI solution following pretreatment in Ca(OH) 2 for various time intervals. The tissue pieces placed in 0.5% NaOCI were not completely dissolved after 12 days. When NaOCI solution was changed every 30 min, the tissue was completely dissolved after 3 h. Pieces placed in Ca(OH) 2 exhibited a marked swelling and a jelly-like consistency. The increase in weight was maintained for 24 h, after which a decrease was noted. After 12 days, the tissue was completely dissolved. Pretreatment with Ca(OH) 2 for 30 min caused the tissue to dissolve in NaOCI within 90 min. Pieces that were pretreated for 24 h or 7 days dissolved within 60 min. As a control, tissue pieces were kept in isotonic saline solution and these were not dissolved after 12 days. Apparently, long-term treatment with Ca(OH) 2 can dissolve necrotic tissue and pretreatment with Ca(OH) 2 can enhance the tissue dissolving effect of NaOCl.

Sealing ability of dental amalgams as retrograde fillings in endodontic therapy

The sealing ability of different types of dental amalgamswhen used as retrograde fillings with and without a cavity varnish was studied. Of the materials tested, a copper-containing spherical amalgam gave the best results. Regardless of material used, the apical seal was significantly improved when a varnish was applied to the cavity prior to the placement of the retrograde amalgam filling.

The use of transparent teeth in the teaching of preclinical Endodontists

Demineralized teeth, which were cleared and hardened in xylene, were used in the teaching of preclinical endodontics. The teeth appeared well suited for the purpose. Of 39 students attending the course, 30 students thought that the use of transparent teeth had facilitated the learning of endodontic techniques.

Host mediators in endodontic exudates: I. indicators of inflammation and humoral immunity

Exudate is often found in the root canal when entering the chamber and canal of teeth with periapical lesions. The aim of this study was to determine possible relationships between clinical or radiographic findings and the concentrations of different host mediators in endodontic exudates. Thirty-two nonvital teeth with periapical symptoms were included in the study. A Clinical Periapical Index was developed to quantify clinical findings. Endodontic exudates were collected with methylcellulose filter paper strips every 3 min, after opening of the pulp chamber. The concentrations of the lysosomal acid glycohydrolase β -glucuronidase, IgG, IgA, IgM, and interleukin-1 β in the endodontic exudates were analyzed. The results demonstrated that exudates collected from teeth with suppuration (cloudy exudates), and teeth with higher periapical index scores (Orstavik et al., 1986) contained higher concentrations of β -glucuronidase and interleukin-1 β . Furthermore, when the periapical index indicated severe involvement, higher IgG was observed in the first samples. The exudates from patients who presented with a sinus tract or swelling contained higher concentrations of IgM, compared with the patients with only periapical sensitivity. Data showed that endodontic exudates from patient with endodontic lesions can be analyzed for host mediators, and differences in the mediators were seen with different clinical and radiographic symptoms.

The prognosis for endodontic treatment of obliterated root canals

Teeth with obliterated root canals were treated endodontically without any surgical procedure. Clinical and radiographic follow-up examinations were performed for 2 to 12 yr. The overall success rate was found to be 89%. When the preoperative periapical status was taken into consideration, the success rate for roots with an intact periapical contour was 97.9%. In teeth with preoperative periapical radiolucencies, a success rate of 62.5% was noted.

pH changes in calcium hydroxide-covered dentin

The pH of dentin in teeth with calcium hydroxide and zinc oxide-eugenol filled cavities was studied in freeze-sectioned young monkeys teeth by means of pH indicators. In untreated dental tissues, the range of pH was found to be 6.4 to 7.4, and the same range of pH was observed when the dentin had been covered with zinc oxide-eugenol. Dentin covered by calcium hydroxide showed a pH range of 11.4 to 12.2 one to three days after application. Seven days after application of calcium hydroxide, the dentin nearest the cavity still showed a pH range of 11.4 to 12.2, whereas the pulpal part showed a pH range of 7.4 to 8.0.

Teeth with transparent roots—An improved teaching aid for preclinical endodontics

A method is described for preparing transparent teeth for preclinical teaching of endodontics. The advantage is that the crown is retained so that access preparation also can be taught.

Host mediators in endodontic exudates. II. Changes in concentration with sequential sampling.

Exudate is often found in the root canal of teeth requiring endodontic therapy. The aim of this study was to evaluate the relationship of sequential changes of different host mediators in endodontic exudates to clinical and radiographic findings. Thirty-two nonvital teeth with periapical symptoms were evaluated. Exudates were collected with filter paper strips every 3 min after opening of the pulp chamber. The concentrations of beta-glucuronidase, IgG, IgA, IgM, and interleukin-1 beta in the exudates were analyzed. In general, the concentration of the mediators in exudates from less involved lesions did not change over time. The exception was an increase in the IgM concentration when patients presented with percussion or palpation sensitivity. In contrast, in the more involved lesions, the concentrations of IgA and IgM increased as sampling progressed. The concentrations of beta-glucuronidase and interleukin-1 beta decreased over time in the more involved lesions. These data suggest that the amount of proinflammatory mediators in the canal and periapical lesion is limited. Furthermore, IgM seemed to be a marker for the severity of periapical lesions. This may relate to vascular permeability that allows passage of this larger molecule into the extravascular environment.