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Fracture resistance of cingulum rest seats in CAD-CAM tooth-colored crowns for removable partial denture abutments.
J Prosthet Dent. 2019 May; 121(5):828-835.JP

Abstract

STATEMENT OF PROBLEM

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.

PURPOSE

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.

MATERIAL AND METHODS

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.

RESULTS

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.

CONCLUSIONS

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).

Authors+Show Affiliations

Graduate student, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash. Electronic address: akchung@uw.edu.Professor Emeritus, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.Clinical Associate Professor and Director, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.Assistance Professor, Department of Restorative Dentistry, School of Dentistry, University of Washington, Seattle, Wash.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

30598310

Citation

Manchester, Joshua A., et al. "Fracture Resistance of Cingulum Rest Seats in CAD-CAM Tooth-colored Crowns for Removable Partial Denture Abutments." The Journal of Prosthetic Dentistry, vol. 121, no. 5, 2019, pp. 828-835.
Manchester JA, Chung KH, Brudvik JS, et al. Fracture resistance of cingulum rest seats in CAD-CAM tooth-colored crowns for removable partial denture abutments. J Prosthet Dent. 2019;121(5):828-835.
Manchester, J. A., Chung, K. H., Brudvik, J. S., Ramos, V., & Chen, Y. W. (2019). Fracture resistance of cingulum rest seats in CAD-CAM tooth-colored crowns for removable partial denture abutments. The Journal of Prosthetic Dentistry, 121(5), 828-835. https://doi.org/10.1016/j.prosdent.2018.08.015
Manchester JA, et al. Fracture Resistance of Cingulum Rest Seats in CAD-CAM Tooth-colored Crowns for Removable Partial Denture Abutments. J Prosthet Dent. 2019;121(5):828-835. PubMed PMID: 30598310.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Fracture resistance of cingulum rest seats in CAD-CAM tooth-colored crowns for removable partial denture abutments. AU - Manchester,Joshua A, AU - Chung,Kwok-Hung, AU - Brudvik,James S, AU - Ramos,Van,Jr AU - Chen,Yen-Wei, Y1 - 2018/12/28/ PY - 2018/03/27/received PY - 2018/08/28/revised PY - 2018/08/29/accepted PY - 2019/1/2/pubmed PY - 2019/11/27/medline PY - 2019/1/2/entrez SP - 828 EP - 835 JF - The Journal of prosthetic dentistry JO - J Prosthet Dent VL - 121 IS - 5 N2 - STATEMENT OF PROBLEM: 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. PURPOSE: 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. MATERIAL AND METHODS: 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. RESULTS: 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. CONCLUSIONS: 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). SN - 1097-6841 UR - https://www.unboundmedicine.com/medline/citation/30598310/Fracture_resistance_of_cingulum_rest_seats_in_CAD_CAM_tooth_colored_crowns_for_removable_partial_denture_abutments_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0022-3913(18)30715-7 DB - PRIME DP - Unbound Medicine ER -