Journal of Dental Medicine

Background and Aim: The majority of commercial curing units in dentistry are of halogen lamp type. The new polymerizing units such as blue LED are introduced in recent years. One of the important side effects of light curing is the temperature rise in composite resin polymerization which can affect the vitality of tooth pulp. The purpose of this study was to evaluate the temperature rise in two different composite resins during polymerization with halogen lamps and blue LED.

Materials and Methods: This experimental study investigated the temperature rise in two different composites (Hybrid, Tetric Ceram/Nanofilled, Filteke Supreme) of A2 shade polymerized with two halogen lamps (Coltolux 50, 350 mW/cm2 and Optilux 501 in standard, 820 mW/cm2 and Ramp, 100-1030 mW/cm2 operating modes) and one blue LED with the intensity of 620 mW/cm2. Five samples for each group were prepared and temperature rise was monitored using a k-type thermocouple. Data were analyzed by one-way ANOVA, two-way ANOVA and Tukey HSD tests with P<0.05 as the limit of significance.

Results: Light curing units and composite resins had statistically significant influence on the temperature rise (p<0.05). Significantly, lower temperature rise occurred in case of illumination with Coltolux 50.There was no significant difference between Optilux 501 in standard curing mode and LED. Tetric Ceram showed higher temperature rise.

Conclusion: According to the results of this study the high power halogen lamp and LED could produce significant heat which may be harmful to the dental pulp.

Background and Aim: Use of provisional restorations is one of the important phases in the treatment of patients who need fixed prosthesis. Some physical properties are required for these materials. The purpose of this study was the comparison of some physical properties of 4 kinds of resins: Trim, Tempron, Duralay (Aria Dent) and Acropars TRII.

Materials and Methods: In this experimental study, transverse-strength (TS), setting time (ST), polymerization shrinkage (PS) and temperature rise (TR) during polymerization were tested. In transverse strength test, 5 samples of each resin were made. TS testing was done with an Instron testing machine. ST testing (5 samples in each group) was done with Gilmore needle. In PS test, 11 cylindric samples were prepared from each resin and the shrinkage was examined with digital micrometer (up to 24 hours). In TR test, after mixing the powder and liquid of resins (8 samples in each group), the temperature rise was recorded with 10 seconds interval (up to 15 minutes). Data were analyzed with one-way ANOVA and Tukey HSD tests with p<0.05 as the limit of significance.

Results: In TS test, all samples of Trim were bent and no fracture was observed, while Tempron and Duralay showed no significant difference. Both Tempron and Duralay revealed high significant difference with Acropars TRII (P <0.01). In ST test, the difference between groups was significant (P<0.01). The lowest ST was observed in Acropars TRII (7 min), and the highest in Tempron (9.53 min). In PS test, significant difference was observed between Trim and Acropars TRII (P<0.01). PS was completed after 120 min in Tempron and Trim groups. However, PS continued to increase in other groups. In TR test, the difference between groups was significant (P<0.05). Duralay showed the highest TR and the lowest was seen in Trim.

Conclusion: In this study, Trim showed better properties than other studied groups. Acropars TRII had the lowest strength. The highest temperature rise was recorded for Duralay and Tempron, respectively.

  Background and Aims: Thermal changes in the oral cavity can be transferred to the implants placed in bone and affect the prognosis of the treatments. Furthermore, some investigators proposed improvement of habitual consumption of hot or cold beverages. The aim of the present study was to measure the effect of temperature changes in the oral cavity following consumption of hot and cold drinks on the temperature of implant.

  Materials and Methods: In this clinical trial, 3 eligible patients were selected. Two months after implant insertion, temperature of the implants was measured following the drinking of hot and cold beverages using a sensor connected to a thermometer. The thermal changes of the implants through the different time intervals were analyzed using Friedman non-parametric test.

  Results: The implant temperatures were significantly increased in the time following drinking of the hot beverages (P=0.009). Furthermore, the implant temperature were statistically decreased in the time after drinking cold beverage (P=0.004). When drinking hot beverages, the maximum and minimum temperatures were 41.57 ⁰ C and 36.77 ⁰ C, respectively. The maximum and minimum temperatures of the implants were also 34.13 ⁰ C and 26.83 ⁰ C , respectively, when drinking cold beverages.

  Conclusion: It seems that the temperatures noted in the implants in the current study cannot weaken the prognosis of implant restorations however, habitual consumption of hot and cold beverages can lead to debilitating implant prognosis and therefore, should be given the necessary warnings to patients.