Feridun Hürmüzlü

Fracture Resistance of Endodontically Treated Premolars Restored with Ormocer and Packable Composite

In this study, mesiodistocclusal (MOD) cavity preparations of endodontically treated maxillary premolars that were enlarged to size #50 were restored using three restorative materials (one ormocer, one packable composite, and one high-copper amalgam) and two application techniques (with or without coronal radicular technique). Copper rings were filled with self-curing polymethylmethacrylate resin and the teeth were placed into resin up to the level of the CEJ. The teeth were grouped according to the restorative material and technique, mounted in a Universal Testing Machine, and the buccal walls subjected to a slowly increasing compressive force until fracture occurred. The force of fracture of the walls of each tooth was recorded and the results in the various groups compared. The group restored with packable composite without radicular extension showed the highest resistance to fracture (p < 0.05). Both groups restored with amalgam were significantly weaker than all the other groups (p < 0.05).

Temperature Rises During Application of Er:YAG Laser Under Different Primary Dentin Thicknesses

OBJECTIVE The present study investigated the effects of the Er:YAG lasers different pulse repetition rates on temperature rise under various primary dentin thicknesses. BACKGROUND DATA The Er:YAG laser can be used for restorative approaches in clinics and is used to treat dental caries. There are some reports that explain the temperature rise effect of the Er:YAG laser. Recently, the Er:YAG laser has been found to play an important role in temperature rises during the application on dentin. METHODS Caries-free primary mandibular molars were prepared to obtain dentin discs with 0.5, 1, 1.5, and 2 mm thicknesses (n=10). These discs were placed between the Teflon mold cylinders of a temperature test apparatus. We preferred three pulse repetition rates of 10, 15, and 20 Hz with an energy density of 12.7 J/cm2 and a 230 μs pulse duration. All dentin discs were irradiated for 30 sec by the Er:YAG laser. Temperature rises were recorded using an L-type thermocouple and universal data loggers/scanners (E-680, Elimko Co., Turkey). Data were analyzed by two-way ANOVA and Tukey tests. RESULTS Whereas the lowest temperature rise (0.44±0.09 °C) was measured from a 10 Hz pulse repetition rate at a dentin thickness of 2 mm, the highest temperature rise (3.86±0.43 °C) was measured from a 20 Hz pulse repetition rate at a 0.5 mm dentin thickness. CONCLUSIONS Temperature rise did not reach critical value for pulpal injury in any primary dentin thicknesses irradiated by a high repetition rate of the Er:YAG laser.

Antibacterial effect of gaseous and aqueous ozone in root canals contaminated with Pseudomonas aeruginosa

This present study attempted to identify the antibacterial effects of aqueous and gaseous ozone in human root canals that are contaminated with Pseudomonas aeruginosa. The differences and antibacterial effects of gaseous and aqueous ozone (manual and ultrasonic) have not been compared to each other yet in any studies. Eighty single-root premolar teeth were prepared and then disinfected and sterilized. P. aeruginosa were incubated in root canals and kept at 37°C for 24 h. The root canals were contaminated with P. aeruginosa divided into 1 positive control, sodium hypochlorite (NaOCl) and three experimental groups: aqueous ozone with manual technique, aqueous ozone with ultrasonic technique and gaseous ozone (n=10). Disinfection procedures were performed for 5 min in order to ensure standardization among all working groups. Remaining microorganism colonies were counted on blood agar plates. Then, data were evaluated and statistically analyzed by one-way ANOVA and Tukey’s test. As a result, although there were no statistically significant differences between the three groups (NaOCl, aqueous ozone with manual, and ultrasonic technique) (P>0.05), there were statistically significant differences between the gaseous ozone and all other groups (P<0.05). Both the manual and ultrasonic techniques of aqueous ozone achieved complete elimination of P. aeruginosa in root canals.