Title: 0397 - Dimensional Discrepancies of Five-unit Zirconia Framework With Various Edentulous Conditions


Lu-Wen Cheng (Presenter)
National Cheng Kung University

Chi-Lun Lin, National Cheng Kung University
Yung-Chung Chen, National Cheng Kung University


Objectives: Dimensional discrepancies of a long-span zirconia framework may result from unfavorable sintering shrinkage or different edentulous conditions. The present study aims to evaluate the dimensional changes of five-unit zirconia frameworks with various distributions of pontics after sintering process.

Methods: Three experimental groups with different edentulous conditions were designed as follows: Group A- missing maxillary lateral incisor and canine; Group B- missing maxillary lateral incisor and first premolar; and Group C- missing maxillary canine and first premolar, was fabricated. After sintering, the specimens were examined using a micro-CT scanner to evaluate their marginal and internal discrepancies. Five critical regions were measured, including mesial marginal gap (MMG), mesial axial wall (MAW), occlusal surface (OS), distal axial wall (DAW) and distal marginal gap (DMG). The measurements were statistically analyzed and between-group differences were assessed with the Tukey’s range test.

Results: All groups showed that the largest discrepancies occurred at the occlusal surface and the smallest discrepancies appeared at the axial walls. The mean marginal discrepancies of Group A, B and C were 142.33µm, 164.83µm and 172.5µm. The mean discrepancies at OS of Group A, B and C were 188.67µm, 234µm and 232.33µm. These results showed that the DMG (156.67µm) was larger than the MMG (147µm) in the central incisor, and the MMG (164µm) was larger than the DMG (141.67µm) in the second premolar. The marginal discrepancies nearby the pontic side were found significantly larger than other sites in Group B only.

Conclusions: Due to the unfavorable sintering shrinkage of zirconia, the largest deformation of the zirconia framework appeared at the occlusal surface. Among three edentulous conditions evaluated in the present study, the framework which restores missing maxillary canine and first premolar demonstrated the best marginal adaptation. The pontics distribution can cause the dimensional discrepancies after sintering process.

Student Presenter

This abstract is based on research that was funded entirely or partially by an outside source:
Ministry of Science and Technology, 106-2221-E-006-140-

Disclosure Statement:
The submitter must disclose the names of the organizations with which any author have a relationship, the nature of the relationship, and the clinical or research area involved. The following is submitted: NONE