Purpose:The purpose of this research project was to determine the clinical success rate
of a lithia disilicate–based core ceramic for use in posterior fixed partial dentures (FPD)
as a function of bite force, cement type, connector height, and connector width.
Materials and Methods:Thirty ceramic FPD core frameworks were prepared using a
heat-pressing technique and a lithia disilicate–based core ceramic. The maximum
clenching force was measured for each patient prior to tooth preparation. Connector
height and width were measured for each FPD. Patients were recalled yearly after
cementation for 2 years and evaluated using 11 clinical criteria. All FPDs were examined
by two independent clinicians, and rankings from 1 to 4 were made for each criterion (4
= excellent; 1 = unacceptable). Results:Two of the 30 ceramic FPDs fractured within the
2-year evaluation period, representing a 93% success rate. One fracture was associated
with a low occlusal force and short connector height (2.9 mm). The other fracture was
associated with the greatest occlusal force (1,031 N) and adequate connector height. All
criteria were ranked good to excellent during the 2-year recall for all remaining FPDs.
Conclusion:The performance of the experimental core ceramic in posterior FPDs was
promising, with only a 7% fracture rate after 2 years. Because of the limited sample size,
it is not possible to identify the maximum clenching force that is allowable to prevent
fracture caused by interocclusal forces. Int J Prosthodont 2004;17:469–475.