fracture resistance of sleeve zirconia bridge (Piolt laboratory study)

Abstract

Background and Aim of study:  The metal sleeve  bridges were previously designed with partial preparations for the abutments  where they leave the occlusal surface without preparation to maintain  the occlusion   and to maintain as much as possible the dental tissue and clinical length of the abutments, which increases the stability of these bridges, and due to the increased cosmetic requirements the idea  originated of making these bridges  from zirconia and this study is interested in assessing its fracture resistance  laboratory.

Materials and Methods: : The test framework was designed as 3- unit bridge with two abutment teeth premolar and second molar of the mandible, a survey of the gypsum example was conducted before preparation and for the gypsum example after preparation by the CAD-CAM  and four bridges were milled and then the fracture  resistance was studied at the Industrial Research Center by applying the head of the test device vertically to each bridge in a specific area and then recorded the force needed to cause breakage in the bridges in Newton. 

Results: The mean of fracture resistance  was 1792 N, where the lowest value was seen at the mesial wall of premolar,  while the highest value at the connector between tne premolar and the pontic  and all  values were within  1541-2152 N.

Conclusions: Within the limitations of this  in vitro study , it is found that sleeve  zirconia  bridges can be resistant to chewing forces if used clinically, compared to the average of  physiological occlusal  force  which about a quarter or half of the resistance of  these bridges.