Nijole A. Remeikis

Effects of long-term exposure of human periodontal ligament cells to milk and other solutions*

Periodontal ligament (PDL) cells cultured from healthy extracted human teeth were exposed to milk, Alcon Opti-Free contact lens solution, K-Mart contact lens solution, saline, and Hanks balanced salt solution. The appearance and rate of loss of the cells from the culture dishes were recorded over time at both room temperature (20 degrees C) and 4 degrees C. The results indicated that saline was superior to either of the contact lens solutions in its ability to maintain the vitality of the PDL cells. Milk at 4 degrees DC provided good short-term viability , but cells did not remain attached after 48 h. At 20 degrees C, however, milk resulted in a 24.4% retention of cells after 72 h. Hanks balanced salt solution was the best storage media, with 46.8% of sells remaining attached after 72 h of exposure. This study supports milk as a good short-term storage medium for maintaining the vitality of PDL cells in vitro.

A comparison of five irrigating solutions: A scanning electron microscopic study

Twenty-five extracted human anterior teeth having one root canal and straight roots were used in this study. The teeth were subjected to routine biomechanical instrumentation and irrigated with one of five irrigating solutions: Salvizol, NaOCl, Gly-Oxide in combination with NaOCl, REDTA, and sterile saline as control. After the experimental procedure, the roots were split and examined in a scanning electron microscope. The results, based on statistical analysis of variance, were that Salvizol, NaOCl, Gly-Oxide with NaOCl, and saline failed to remove the smeared layer. REDTA was the most efficient irrigation solution in removing the smeared layer.

Effective shelf-life of prepared sodium hypochlorite solution

Although the tissue solvent and bactericidal properties of sodium hypochlorite are well known, the effective shelf-life of prepared sodium hypochlorite solutions is not known. The stability of sodium hypochlorite is adversely affected by exposure to high temperature, light, air, and the presence of organic and inorganic contaminants. The purpose of this study was to investigate the variables of storage conditions and time on the tissue-dissolving capacity of three different concentrations of sodium hypochlorite. Fresh frozen human umbilical cord was used as the tissue sample for this experiment. Tissue samples were dissolved at time intervals ranging from 1 day to 10 wk in 5.25%, 2.62%, and 1.0% solutions of sodium hypochlorite. The tissue-dissolving ability of 5.25% sodium hypochlorite remains stable for at least 10 wk. The tissue-dissolving ability of 2.62% and 1.0% sodium hypochlorite remains relatively stable for 1 wk after mixing, then exhibits a significant decrease in tissue-dissolving ability at 2 wk and beyond.

Ultrasonic compared with hand instrumentation: A scanning electron microscope study

Scanning electron micrographs were used to compare the effectiveness of two methods of cleansing, shaping, and enlarging root canals of human teeth. Eleven extracted maxillary central incisors were instrumented by ultrasonically activated K files and diamond files with a constant high volume of 2.625% NaOCl irrigation. Another 11 maxillary central incisors were hand instrumented with conventional endodontic K files with a high volume of 2.625% NaOCl irrigation. Scanning electron micrographic photographs of the prepared canal walls were made at three levels in the root and were evaluated both quantitatively and qualitatively. On the basis of remaining debris, presence of a smear layer, and patency of dentinal tubules, no significant difference between the two methods was found at the apical or coronal level of the root canal. At the mia-level hand instrumentation produced significantly cleaner canal walls. A smear layer remained on the canal wall after both methods.

McSpadden versus lateral condensation: The extent of apical microleakage*

In this study 34 extracted human single-rooted teeth were instrumented and randomly divided into three groups. Three sets of 10 teeth were obturated by either lateral condensation with sealer or by mechanized thermoplastic condensation with and without sealer. Four teeth were used as controls. Following obturation the teeth were immersed in a 45 Ca solution and autoradiographs were taken to compare leakage of the different filling procedures. Lateral condensation with sealer produced a better seal than thermoplastic obturation with or without sealer. The difference was statistically significant.

Dentinal dysplasia, Type I. Report of a case with endodontic therapy.

The first reported case of endodontic therapy in dentinal dysplasia, Type I, is described. The first histologic diagnosis of periapical granuloma instead of periapical cyst in dentinal dysplasia, Type I, is also reported.

Instrumentation of curved root canals: A comparison study

Flex-R, Flex-O, and K-Flex files were compared using a circumferential filing technique on 30 extracted human molars. The buccal canals of maxillary molars and mesial canals of mandibular molars were utilized. The minimal initial curvature was 18 degrees. Canal curvature was measured before and after filing, and changes were analyzed statistically. Analysis showed that, no matter which of the instruments was used, the angle of curvature was maintained with a high degree of accuracy.

Twelve-year follow-up of a replanted incisor

A case report with a 12-yr follow-up of a replanted maxillary incisor is presented. A maxillary incisor, #8, with incomplete root formation was replanted without splinting following a 2-h sojourn in salt water. The pulp responded positively to the electric pulp tester for 2 yr. There was no response to the electric pulp tester 5 yr postoperatively. Although there was some external root resorption, the root appeared to have reached normal length. Two parallel vertical radiolucent slits were present in a trabeculated substance in the site normally occupied by the pulp. This case illustrates an example of revascularization and pulp obliteration. Interestingly, at the 12-yr follow-up, the replanted tooth, as well as tooth 7, showed blunted apices that occurred following orthodontic tooth movement.