The different between Open Tray Transfer and Close Tray Transfer

 

With the popularization of implant technology in the Chinese market, a large number of active restorations have been replaced by implant surgery. In theory, this is a great progress in the field of Chinese dentistry. However, because the lower implant, the abutment and the upper restoration are not well matched, it is easy to cause food residues and bacteria to continuously stimulate the gingival tissue, thereby affecting the final service life of the implant.

 

One of these issues is the quality of the implant abutment and the fit of the abutment to the implant. The implant abutment is a very precise part of the denture, and the accuracy of its joint is usually 0.003 mm. This accuracy refers to the perimeter accuracy, which is the result of the sum of the accuracy errors of the four surfaces of the abutment's connection. Therefore, it is particularly important whether the doctor can provide high-precision impressions to the laboratory.

 

 

 

Regular impression taking means that the doctor takes the impression directly after fixing the finished abutment in the mouth. The laboratory can only make restorations on plaster abutments.

 

However, there are many disadvantages in regular impression taking, and many doctors no longer use it.

 

 

Disadvantages of Regular impression taking

 

1. Taking molds directly, the expansion coefficient of gypsum is not easy to control, so the accuracy has a certain influence. Cause adverse effects of later restoration.

2. If artificial gingiva is not used, the edge of the abutment and the crown will not fit tightly, and it is easy for food residue to enter and affect the service life of the implant.

3. If there are multiple implants with poor seating conditions, after taking the impression directly, the laboratory cannot correct the common positioning path on the precision grinding instrument. It affects the difficulty of post-processing and increases the rate of clinical rework.

4. For some cases requiring personalized abutment restoration, direct impression taking cannot be done.

 

 

 

The transfer of implants can be divided into two methods: open-tray and closed-tray techniques. Currently, over 95% of doctors use the open-tray method for imprinting.

 

Open Tray Transfer

The mold obtained using a transfer system with trays for opening and fixed screws is called an open-tray. The open-tray has a higher accuracy.

 

Operation Methods of Open Tray Transfer Impression

1. First, fix the transfer pole to the implant with screws, and then try on individual trays with open windows to determine that the screws can be threaded out from the window.

2. Place the tray containing the silicone rubber impression material into the mouth and let it sit for about 4-5 minutes until the impression material sets. After the material has solidified, loosen the fixing screw from the opening and completely remove the tray from the mouth.

3. Transfer the fixed screw out of the cavity together with the mold and then install the replacement body inside the mold. Fix the replacement body on the transfer rod with the fixed screw, and then pour the plaster model after setting the denture gum.

 

Operation Methods of Closed Tray Transfer Impression

1. The transfer bar has an elastic structure and can be directly fixed to the implant in a clamping form without the need for fixing screws.

2. When taking an impression, the enclosed tray filled with silicone rubber impression material is placed directly in the mouth and positioned. After the impression material has set, the tray is removed from the mouth and the transfer handle is carried out of the mouth.

3. Then fix the transfer post in a certain direction to the impression material by snapping it into place, and pour gypsum model after setting fake gum.

 

The closed-tray transfer impression operation is relatively simple but its accuracy is slightly lower, so it is also less commonly used in practical applications.