Topographic aspects of airborne contamination caused by the use of dental handpieces in the operative environment.

BACKGROUND: The use of dental handpieces produces aerosols containing microbial agents, bacteria, and viruses representing a high-risk situation for airborne cross infections. The aim of this study was to map and quantify the biological contamination of a dental operatory environment using a biological tracer. METHODS: Streptococcus mutans suspension was infused into the mouth of a manikin, and an operator performed standardized dental procedures using an air turbine, a contra-angle handpiece, or an ultrasonic scaler. The presence of the tracer was measured at 90 sites on the dental unit and the surrounding surfaces of the operatory environment. RESULTS: All tested instruments spread the tracer over the entire dental unit and the surrounding environment, including the walls and ceiling. The pattern and degree of contamination were related to the distance from the infection source. The maximum distance of tracer detection was 360 centimeters for air turbine, 300 cm for contra-angle handpiece, and 240 cm for ultrasonic scaler. No surface of the operative environment was free from the tracer after the use of the air turbine. CONCLUSIONS: Attention should be paid to minimize or avoid the use of rotary and ultrasonic instruments when concerns for the airborne spreading of pandemic disease agents are present. PRACTICAL IMPLICATIONS: This study supports the recommendations of dental associations to avoid treatments generating aerosols, especially during pandemic periods. Guidelines for the management of dental procedures involving aerosols, as well as methods for the modification of aerosols aimed to inactivate the infective agent, are urgently needed.

The strip method and the microelectrode technique in assessing dental plaque pH.

BACKGROUND: The pH strip method has been proposed for use in a clinical setting for the evaluation of dental plaque pH. The aim of this in-vivo study was to compare the reliability of the pH-indicator strip method to the microelectrode technique in plaque pH measurement. METHODS: 136 subjects (7-9 years) were enrolled and, for each subject, measurements of plaque pH were made at two interproximal sites; a total of 272 sites were analyzed. Plaque pH was assessed in triplicate using pH-indicator strips (pH range: 4.0-7.0) and an iridium microelectrode with a diameter of 0.1 mm. The caries status of 544 proximal surfaces between two primary molars, in proximity at the plaque pH sites, was assessed. All measurements were performed before and 2, 5, 10, 15, 20, and 30 minutes after a mouth rinse with water solution of sucrose (10%). One-way ANOVA was performed to analyze statistically significant differences between the two techniques. Instrument reliability was measured by assessing the intraclass correlation coefficient. RESULTS: Comparable, not statistically significant pH values (P values range from 0.98 to 1.00) were obtained by the two methods for AUC5.7, AUC6.2, maximum pH fall and minimum pH. High intraclass coefficients were recorded (Pearson's r=0.96, Yule's Q=0.99), implying an almost perfect association when the measurements were grouped as a carious lesion being present or not on the surface near the site of measurement. CONCLUSIONS: The use of the pH strip method has high validity and may replace the traditional microtouch electrode technique for clinical use.

Chlorhexidine concentration in saliva after topical treatment with an antibacterial dental varnish.

PURPOSE: To evaluate the salivary levels of chlorhexidine (CHX) after a single professional treatment with an antibacterial dental varnish (Cervitec) containing 1% CHX and 1% thymol. METHODS: Unstimulated whole saliva from 21 healthy young adults was collected at baseline and up to 24 hours after treatment at designated time intervals and the CHX levels in saliva were quantified with high-performance liquid chromatography. Post-treatment saliva samples were added to suspensions of mutans streptococci and supragingival dental plaque for a growth inhibition. RESULTS: CHX concentration in saliva showed a peak value (76.5 microg/ml) after 5 minutes followed by a slow decrease with time. The elevation was statistically significant (P < 0.05) up to 4 hours after the application of the varnish and the recorded values were back to baseline levels after 24 hours. The 2- and 4-hour post-treatment saliva samples inhibited growth of mutans streptococci by 46% and 33%, respectively.