ABSTRACT
A two-year clinical study was done on 100 patients to study marginal deterioration and microleakage of an experimental gallium alloy and two commercially available amalgam alloys. The amalgam alloys represented conventional low copper [Amalcap] and high copper [Tytin] alloys. The marginal quality was studied on class 2 lower molars of 40 patients with total number 120 cases, while microleakage was studied on class 4 premolars of 60 patients [buccaly and lingually] to be extracted for orthodontic treatment [total 120 restoration]. Each of the studied properties were tested in 1-hour, 1-month, 1-year and 2 year periods. Marginal quality was tested by two methods: Direct observation and ranking photographs. Three evaluators evaluated each case and the average results were taken, while microleakage was studied by immersing the extracted tooth in methylene blue dye and scoring the degree of dye penetration seen in photographs. The teeth were extracted in the different 4 periods tested. The observed results showed that, gallium alloy showed superior marginal quality and superior marginal seal in all the tested periods. The ranking order of marginal quality was: Gallium alloy the best, Tytin the second and the worst was Amalcap. Microleakage observed was highest with Amalcap, then Tytin and the least was galium alloy. Aging played an important role in both microleakage and marginal deterioration. Strengths properties, creep, dimensional changes and corrosion greatly affected both studied properties. Marginal deterioration increased microleakage