A Study On Manufacture And Clinical Practice Of Dental Finished Key-Keyway Attachments

Purpose: The attachment dentures have more advantages than the traditional partial dentures, such as esthetics, comfort and good oral hygiene and periodontal health, but the traditional manufacture procedure is complex and requires a higher technique. Moreover the parts of the attachment are semi-finished, through the manufacture procedure, the accuracy of attachment dentures is reduced. This subject applies precise processing technique to prosthodontics to manufacture finished precision attachments, select the suitable parameters of laser welding, and then use them in clinic. There are a few domestic attachments by now, moreover most of them are semi-finished attachments. In order to change this situation, reduce production costs, promote the accuracy of the attachment dentures, simplify the manufacture procedure and accelerate attachments to be used in a largerrange, we designed these attachments .The effect of attachments is proved by the clinical practice.Methods: By studying and analyzing other attachments, we design this type of attachment, and then manufacture finished attachments through precise process technique on lathe. Apply the laser-welding technique to the manufacture of the attachments dentures, and then test the accuracy of the attachments. We use them in clinical practice and prove the mechanical properties in the clinical situations.Results:1 .The attachments have smooth surface, accurate size and harmless material. The allowable tolerance is less than 0.01mm.2.The mechanical properties of the laser welding meet the requirements of the clinic practice. Under the different laser-welding setting parameters, the breaking intensity of Co-Cr alloy are 360Mpa,415Mpa,580Mpa; the breaking intensity of Ni -Cr alloy are 310 Mpa, 405 Mpa, 566 Mpa; the breaking intensity of Ti are 221 Mpa, 180 Mpa, 154 Mpa. Accompany with the increase of voltages, thewelding-depth and heat influence area increased./3. The main presentation of the laser welding to the porcelain is themicro-gaps among the range from 800-1000 u m to the welding area4. It is proved that dentures with attachments are easy to insert,stable, beautiful and efficient in mastication. Patients feel comfortable. Conclusion:1. This subject applies precise processing technique to manufacture finished precision attachments; the tolerance is less than 0.01mm andit meet the standard of the precision attachment.2. Under the suitable setting parameters, this subject applied the laser-welding technique to the manufacture the attachment dentures and can accomplish various tasks of laser-welding .The mechanical properties meet the requirements of the clinical practice.3.The laser-welding can affect the porcelain of the PFM crown within 1 mm. Beyond this distance, the affection can be ignored.4.It is proved by 35 clinical practices that the prostheses made by laser welding have a better effect and promoted stability and accuracy. There was no joint fractures and corrosions and color changes.