MERCURY RELEASE FROM DENTAL AMALGAMS - AN IN-VITRO STUDY UNDER CONTROLLED CHEWING AND BRUSHING IN AN ARTIFICIAL MOUTH

The release of mercury vapor from class I amalgam restorations prepare d in human molar teeth was studied during chewing simulations in an ar tificial mouth of a bi-axial servo-hydraulic mechanical test system. S o that the total mercury released from the restoration over a fixed ti me could be determined, a closed chamber surrounded the envelope of ch ewing motion. In addition, the influence of sampling frequency on merc ury release was corrected by the use of different sampling frequencies over a fixed time interval of mercury release measurement and extrapo lation to zero sampling time. Thus, a combination of a closed environm ent and an extrapolation method to determine the mercury release under continuous sampling was used to determine the mercury released under normal breathing conditions. The measured mercury release rate data we re used to calculate the potential daily mercury dose in a patient due to a single amalgam restoration, following the method previously outl ined by Berglund. The mercury release from both a conventional and a h igh-copper amalgam was evaluated at different age intervals after the restoration was placed in the teeth. The results show that while the a ge of the amalgam and the amalgam type influence the extent of mercury release during the initial non-steady-state conditions, the steady-st ate value of mercury daily dose due to a single amalgam filling is 0.0 3 mu g/day, which is well below the calculated threshold-limiting valu e (TLV) of 82.29 mu g/day considered dangerous for occupational exposu re in the United States.