Disposable Plastic Tray Compared to Metal Border-Lock Tray

Compared to metal trays, disposable plastic trays provide a clean working environment that saves time on cleaning, sterilizing, and disinfection. Disposable trays can be reused and are ideal for catering events, receptions, and weddings. They can also be used for food storage and plant handling.

A recent study compared the performance of plastic impression trays to metal border-lock trays in impression-taking. In addition to determining dimensional accuracy of plastic impressions, the study also investigated the effects of tray type on the precision of plaster casts. Plastic trays had lower accuracy and angular deviation than metal trays. The differences between the two groups were not clinically relevant.

Plastic trays were used for impressions taken with the VPS material and in the one-step dual-phase impression technique. Using a type IV dental stone with 0% expansion, impressions were poured into disposable plastic trays and then stored for 5 minutes in a disinfection solution. A plaster cast was then created. The cast was scanned to measure the trueness and dimensional accuracy of the impression. The plaster cast was then compared with a reference model.

For all impressions, local accuracy was excellent. The mean deviations of measurement paths were also lower in plastic trays than metal trays. The deviations between the precision balls were small for both PE and VPS material. For fixed dental prostheses, the deviations were less for PE and VPS material. For short fixed partial dentures, the deviations were less for plastic trays and not significantly different from metal trays.

For the metal tray group, the setting time of impression materials was twice the clinical working time. The trays were also cleaned before being reused. The total tray coverage is important for keeping fewer trays tied in sterilization and cleaning. The new generation of stock plastic trays is designed with a retentive fleece to keep the cured impression material in place. The new plastic tray might also have a higher torsional rigidity than the older plastic trays.

Disposable stock plastic trays were also compared to metal trays for accuracy. The trays were then scanned to measure the trueness of the impressions. The angular deviations were smaller for the plastic tray than for the metal tray, with the highest deviations occurring when using VPS impression materials. The distance changes between precision balls were also smaller in plastic trays than in the metal trays. However, the angular deviations between the prepared to abutment angles were not significant.

For metal trays, the total tray coverage was not significantly different from the plastic trays. The differences in angular deviations were not clinically significant. However, the difference in the advantage of the metal trays was statistically significant when the precision range was 6 to 16 mm.

The plastic trays had a significant disadvantage when compared to metal trays in terms of precision. The differences between the metal and plastic trays were not clinically relevant, and further investigation of the differences did not show any significant differences in trueness.