Tuesday, March 20, 2018

The Dentist's Exposure to Elemental Mercury Vapor During Clinical Work with Amalgam

Resident: Suhyun Rue, DMD                                                                       Date: 03/ 21 /2018
Article Title: The Dentist's Exposure to Elemental Mercury Vapor During Clinical Work with Amalgam
Author(s): L. Pohl and M. Bergman
Journal: Acta Odontol Scand (1995)53 :44-48
Date: 1995
Main Purpose: 
This study’s aim was to evaluate exposure to mercury vapor by means of a continuous measurement device while using various dental suction devices. All experimental data were collected during routine clinical work in a public dental health clinic. 
Background:
-The dentist’s occupational exposure to mercury vapor occurs to a large extent during cutting, filling, and polishing operations.  
-Previous studies used intermittent sampling with “mercury vapor sniffer equipment” that had made it difficult to properly evaluate experimental data about measuring mercury vapor during clinical operations.  
-In the present study, it was possible to measure continuously the amount of mercury in the breathing zone of the dentist during cutting, placing, and polishing of amalgam restorations
-Previous in vitro studies indicated that rapid changes of mercury vapor levels will occur, especially during the cutting of amalgam
Summary:
-Fifty amalgam fillings were removed (mainly due to secondary caries but a “few” because of technical defects) and replaced with new amalgam fillings.
-An additional 30 fillings were polished.
-Three kinds of suction were used: high volume evacuation (HVE), saliva extractor (SE), and a mirror-evacuation (ME) which is a combination of a dental mirror and suction device with an evacuating capacity.
-The mercury vapor was sampled and measured by means of a measuring system based on atomic spectrophotometry that had a plastic sampling tube attached to the dentist’s glasses to allow for continuous measurement.
-Seven different measurement series were performed and the amount of vapor was measured with different combinations of cutting and/or filling and/or polishing with HVE, SE, and/or ME.  
-The results showed that the maximum amount of mercury vapor collected in the “breathing zone” of the dentist was during cutting and filling with new amalgam with SE alone.
-If only a saliva extractor is used during cutting per se, high mercury vapor levels may be attained.  When HVE was using during cutting, filling, and polishing, the mean mercury vapor levels were 1-2 ug/m(acceptable short term exposure, STE, is 150 ug/min a 15 minute period).
-These levels are not exceeded during the polishing of amalgam, even without the high volume evacuator, provided water coolant is used.   The authors conclude that in order to minimize a dentist’s exposure to mercury vapor during clinical work, a conventional high volume suction evacuator must be used.


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