Substantivity of hypochlorous acid-based disinfectant against biofilm formation in the dental unit waterlines.

OBJECTIVE: The purpose of the study was to examine the substantivity of a new disinfectant against biofilm formation in the dental unit waterlines. MATERIALS AND METHODS: Twenty dental units were selected for the study and divided into two groups: Group A (dental unit waterlines treated with the disinfectant) and Group B (untreated dental unit waterlines). Biofilm formation was monitored in both groups by removing the one dental unit waterline from each group for the period of 10 days. One inch of the dental unit waterline tube was cut at random site, and the inner lumen of the cut sections was analyzed using the scanning electron microscope (SEM) (TESCAN VEGA3 SBU). RESULTS: On examination, SEM images showed that there was no slime layer or bacterial cells seen in cut section for the period of 7 days in the treated dental waterlines, which means that there is no evident of biofilm formation. In the untreated dental unit waterline cut section, slime layer was observed from day 1. CONCLUSION: Disinfectant solution was proved to be effective for 7 days against biofilm formation. This technique could be used as a valid method for disinfection of dental unit waterlines.

Effects of elevated temperatures on various restorative materials: an in vitro study.

In cases of mass disasters associated with fire, identification of the burnt victims can be a real challenge to the forensic team. Teeth and their restorations play a significant role to aid in the identification process, as various restorative materials have varying resistance to high temperatures. A study was undertaken to evaluate the changes taking place on teeth restored with amalgam, composites, glass ionomers, heat cure acrylic, and ceramics. The specimens were placed in a furnace and heated to predetermined temperatures of 200, 400, 600, 800, and 1000 degrees C and the changes were examined using a digital camera and stereomicroscope. Our observations show that while some restorations were able to withstand elevated temperatures, others were reduced to an unrecognizable mass at relatively low temperatures.

In vitro pulp chamber temperature rise during composite resin polymerization with different curing lights.

The damaging effect of temperature increase on the pulp tissue during restorative treatment has been a matter of concern in dentistry for many years. Aesthetic restorative dentistry relies on polymerization of light-activated resin composites which can cause damaging effects to the dental pulp as a result of temperature rise caused by both the exothermic reaction process and the energy absorbed during irradiation. This in vitro study was carried out to measure the increase in pulp chamber temperature induced during composite resin-polymerization with various light curing units in three different and common clinical situations (Veneer, Class II, Class III) and the clinical implications of the results. Measurement of pulp temperature changes during polymerization was performed with a Al-Cr Thermocouple positioned at the pulp-dentin junction. Mean values were calculated from six measurements with each light curing unit.

pH stabilizing properties of a posterior light cured resin composite: an in vivo study.

This study evaluated, in vivo, the pH stabilizing properties of a posterior resin composite (Ariston pHc, Vivadent Ets, Schaan/Liechtenstein). Fifteen human subjects with four or more active carious lesions were selected. Their salivary pH, in relation to the occlusal surface of these lesions, was recorded. The teeth were restored with resin composite, and the pH in relation to the restorations was recorded one day, one week, one month and two months postoperative. Results showed that the resin composite countered the acidic pH of saliva and maintained it at levels where demineralization would not occur.

Prevention of caries by pulsed CO2 laser pre-treatment of enamel: an in-vitro study.

The aim of the study was to assess the caries inhibitory potential of carbon dioxide laser and explore the effect of the number of pulses used to correlate caries inhibition. Caries free human mandibular molars were irradiated with carbon-dioxide laser of wavelength 10.6 microm at 5, 15, 25, 50 and 100 pulses. Simulated caries lesions were allowed to form by immersing the teeth in artificial caries medium for three weeks. Thin sections of 75 microns were obtained by using hard tissue microtome. These sections were observed under polarizing microscope, caries lesions were identified and their depth was measured. These values were subjected to statistical analysis. The results showed that carbon-dioxide laser irradiation can inhibit caries like lesion upto 82.7% and it was optimal at 25 pulses.

Apical third instrumentation of curved canals with K-type and canal master instruments.

Forty acrylic blocks with curved canals were divided into two groups of 20 each. One group had canals with 30-degree curvature and the other with 45-degree curvature. Each group was divided into two subgroups of 10 blocks each. One subgroup was instrumented with precurved Kerr files and the other was instrumented with Canal Master hand instruments. The efficiency of the two instruments for preparing the apical third of curved canals was compared. In plastic blocks, Canal Master caused less transportation and was more suitable for instrumenting the canals.