Fracture resistance of cingulum rest seats in CAD-CAM tooth-colored crowns for removable partial denture abutments
| Autor: | James S. Brudvik, Yen-Wei Chen, Van Ramos, Kwok-Hung Chung, Joshua A. Manchester |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Dental Stress Analysis
Ceramics Materials science medicine.medical_treatment 03 medical and health sciences 0302 clinical medicine Dental porcelain CEREC Materials Testing Stereo microscope medicine Dental Restoration Failure Cingulum (tooth) Retrospective Studies Retainer Orthodontics Universal testing machine Crowns 030206 dentistry Dental Porcelain Dental Prosthesis Design Computer-Aided Design Denture Partial Removable Oral Surgery Dentures Removable partial denture |
| Zdroj: | The Journal of Prosthetic Dentistry. 121:828-835 |
| ISSN: | 0022-3913 |
| DOI: | 10.1016/j.prosdent.2018.08.015 |
| Popis: | The prevalent use of computer-aided design and computer-aided manufacturing (CAD-CAM) for tooth-colored ceramic materials has led to several case reports and retrospective clinical studies of surveyed crowns used to support removable partial dentures. How the specific contour of a cingulum rest seat affects the fracture resistance of these CAD-CAM tooth-colored materials is unknown.The purpose of this in vitro study was to compare the fracture resistance of monolithic CAD-CAM tooth-colored mandibular canine-surveyed ceramic crowns with cingulum rest seats of different designs.Five groups (n=24/group) of CAD-CAM tooth-colored crowns were milled from the same standard tessellation language (STL) file: group EM, lithium disilicate-based material (IPS e.max CAD CEREC blocks); group SM, zirconia-based material (NexxZr T); group LP, zirconia-based material (Lava Plus High Translucency); group ZC, zirconia-based material (ZirCAD LT); and group MZ, composite resin (MZ100 CEREC blocks), used as a control. Crowns from each group were divided into 2 subgroups representing 2 shapes of cingulum rest seat design: round design subgroup (n=12) with 0.5-mm radius of curvature and sharp design subgroup (n=12) with 0.25-mm radius of curvature for the rest seat preparation. The crowns were cemented with resin cement to a composite resin die on a steel nut. After 24 hours of storage in water at 37°C, the specimens were statically loaded to fracture with a custom metal retainer on top of the cingulum rest seat by using a universal testing machine at a crosshead speed of 1.5 mm/min. Two-way ANOVA and the Tukey honestly significant difference tests were used to control the familywise error rate (α=.05). Representative specimens were examined using an optical stereomicroscope at ×10 magnification and a scanning electron microscope to determine the failure patterns and fracture mechanism.The results of the ANOVA test indicated statistically significant differences by materials and rest seat designs (P.001). The mean ±standard deviation maximal load capacity was 773.5 ±255.0 N for group MZ, 1124.9 ±283.9 N for group EM, 2784.1 ±400.5 N for group SM, 2526.9 ±547.1 N for group LP, and 3200.8 ±416.8 N for group ZC. The round design subgroups had an approximately 30% higher mean failure load than the sharp design subgroups for all surveyed crowns.The present in vitro study demonstrated that zirconia-based groups fractured at twice the load as the lithium disilicate group. Of the 3 zirconia-based groups, group ZirCAD had a statistically greater fracture resistance than the other groups. Designing the cingulum rest seat to have a broad round shape provides a statistically significant higher fracture resistance than a sharp-shape design (P.05). |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|
Full Text from ScienceDirect