Statement Of Problem: For patients with limited interocclusal space, standard height implant abutments may not be usable. Shorter abutments may be desirable.
Purpose: The purpose of this study was to determine the effect of the height of titanium abutments on the tensile strength required to dislodge zirconia copings.
Material And Methods: Two experimental groups of abutments were prepared: (1) 4.3-mm platform width implant abutment with a 6.5-mm height (control), and (2) a 4.3-mm platform width implant abutment with a 5.5-mm height (shorter). Each abutment had 5 zirconia copings (custom designed) fabricated through a 3-dimensional computer-assisted design (3-D CAD) process by scanning an identical wax pattern. The zirconia copings were designed to have a 6-mm projection above the titanium abutment to accommodate a 2-mm hole. A wire was inserted through this hole to attach the zirconia coping to a universal testing machine. Each abutment was placed onto an implant embedded in a brass base designed to fit onto the universal testing machine. The zirconia copings were cemented onto the abutments with a provisional luting agent (Improv), and a tensile force was applied at a crosshead speed of 0.5 mm/min. The removal force was recorded for each specimen. An unpaired t test was used for the statistical analysis (alpha =.05).
Results: The mean force (SD) necessary to remove the zirconia copings (Newtons) from the 6.5-mm titanium abutment (198.09 (28.83)) was higher (P=.0078) than for the 5.5-mm abutment (124.89 (36.388)).
Conclusions: By increasing the height of the abutment 1 mm and maintaining the diameter of the abutment, the resistance to tensile forces increased significantly between the 2 abutment dimensions evaluated.
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http://dx.doi.org/10.1016/S0022-3913(08)60005-0 | DOI Listing |
J Indian Prosthodont Soc
January 2025
Department of Prosthodontics, Chhattisgarh Dental College and Hospital, Rajnandgaon, Chhattishgarh, India.
Aim: The aim of this study was to compare the marginal accuracy of polyetheretherketone (PEEK) and zirconia copings fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) technology, and to assess the impact of their material properties on accuracy when produced with a 4-axis milling system under controlled conditions.
Settings And Design: The study employed an in vitro design with a stainless steel die model featuring a 6 mm axial wall height, a 6-degree total occlusal convergence, and a radial shoulder finish line.
Materials And Methods: Thirty stone dies were created from silicone impressions of the metal die and poured using type-IV dental stone.
Cureus
October 2024
Department of Prosthodontics, Maharaja Ganga Singh Dental College and Research Centre, Sri Ganganagar, IND.
Introduction: The marginal fit of dental restorations is essential for longevity and effectiveness of fixed prostheses, particularly single-unit crowns. Direct digital scanning offers significant advantages over indirect methods, providing a non-invasive, accurate, and reproducible means to evaluate marginal fit. This study aimed to assess the marginal fit of single-unit copings fabricated using computer-aided design/computer-aided manufacturing (CAD/CAM) zirconia, direct metal laser sintering (DMLS), and porcelain-fused-to-metal (PFM) utilizing direct three-dimensional (3D) scanning.
View Article and Find Full Text PDFEur J Prosthodont Restor Dent
November 2024
Center for Dental Medicine, Clinic of Masticatory Dysfunction and Dental Biomaterials, University of Zurich, Zurich, Switzerland.
Aim: To compare the tensile strength, dislodgement forces, marginal gap and failure types between digitally fabricated zirconia root copings and conventionally manufactured cast gold root copings.
Methods: Extracted human teeth (N=30) were prepared for the root copings and randomly divided into 2 groups: (1)zirconia root copings(ZC) and gold root copings(GC). The specimens were tested for tensile bond strength and dislodgement forces in a universal testing machine and the types of the coping failures modes were analyzed.
Objective: The purpose of this study was to assess the accuracy of full coverage crowns produced by two manufacturing methods: additive 3D printing and subtractive milling utilizing three different predefined cement spaces.
Materials And Methods: Six groups were allocated based on the manufacturing method and the predefined cement space: printed wax with a 20 µm space (PW1); printed wax with a 50 µm space (PW2); printed wax with a 100 µm space (PW3); milled wax with a 20 µm cement space (MW1); milled wax with a 50 µm cement space (MW2); milled wax with a 100 µm cement space (MW3); milled zirconia coping with a 20 µm cement space (MZ1); milled zirconia coping with a 50 µm cement space (MZ2); milled zirconia with a 100 µm cement space (MZ3). All fabricated specimens were scanned using an Identica Blue 3D scanner and saved as standard tessellation language (STL) files.
Int J Dent
October 2024
Department of Prosthodontics, University Clinic Heidelberg, University of Heidelberg, Heidelberg, Germany.
To evaluate the fracture resistance of veneered incisor crowns made from highly translucent zirconia frameworks. Ninety-six all-ceramic single crowns were based on either a coping with minimum wall thickness or a cutback framework fabricated from highly translucent zirconia (5Y-PSZ). Each one-third of the specimens was finalized with different veneering ceramics using standardizations and glaze firing.
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