HiPer®-DENT-Z Dental Blanks
Information for Dentists
All-ceramic dental restorations manufactured from HiPer®-DENT-Z zirconia is aesthetically appealing and mechanically very robust. To obtain best possible results application and preparation need to follow certain procedures. The hereafter given information does not replace the instructions for use delivered with each product but provides additional explanation to the attending dentist. Please ask us for a copy of the instructions if it is not available for you.
Material Properties: Zirconia
Ceramic frameworks are in most cases manufactured from yttria-partially stabilized zirconia. A solid solution of yttrium ions in the zirconia lattice giving rise to retention of a high temperature crystallographic phase during cooling to room temperature explains the outstanding material characteristics. The material toughening mechanism is based on prevention of stress-induced crack propagation by phase transformation, therefore called transformation toughening. The latter also responsible for the high modulus of rupture of zirconia.
The mechanical strength of a restoration depends also on condition of finishing tools, the sintering regimen and the number of veneering cycles. Also preparation borders and remachining affect the clinical performance of prothesis.
Preparation
For avoiding unacceptable thin wall sections in zirconia frameworks tooth preparation should be done as chamfer or rounded shoulder. Edge radius should be 0,7 mm or more.
A cutting depth of at least 1 mm should be choosen allowing a sufficient wall thickness of the restoration. The preparation angle should be in the range between 6° and 8°. Occlusal and incisal a removal of at least 1,5 mm is strongly recommended, better would be 2 mm.
Multi-unit frameworks should not have more than two pontics between two abutment teeth.
Insertion of Restorations
Generally speaking remachining before insertion of a restoration should only be done if absolutely necessary. Due to the great hardness of zirconia such procedures should only be conducted with suitable diamond tools and with sufficient water cooling. Both measures prevent the restoration from cracks induced by thermal stress.
The tool pressure during removal of material should be kept moderate and a sufficient sharpness of the applied diamond tool has to be ensured. Sharp edges or grooves on the framework have to be smoothened before insertion. During insertion test for possible friction of the restoration on the tooth stomp.
Sandblasting of the inner surface of your restoration (e. g. alumina sandblasting medium 110 µm) before insertion is acceptable, yet not necessary, if the surface is clean. Recommendations for remachining of the veneer ceramic are available from the instructions for use for the applied veneering ceramic product.
