All ETDs from UAB

Advisory Committee Chair

John O Burgess

Advisory Committee Members

Nathaniel C Lawson

Amjad Javed

Jack E Lemons

Daniel Givan

Document Type

Thesis

Date of Award

2019

Degree Name by School

Master of Dentistry (MDent) School of Dentistry

Abstract

SURFACE TREATMENT EFFECTS ON SHEAR BOND STRENGTH AND BIAXIAL FLEXURAL STRENGTH OF THREE GENERATIONS OF ZIRCONIA YASKO A. DARKOUE MASTER OF SCIENCE IN DENTISTRY ABSTRACT Objectives: Mechanical and chemical surface treatments are required to achieve a durable bond to zirconia. The objective of this study is to compare the effects of particle abrasion and pressure on shear bond strength and biaxial flexural strength of Lava (Frame, Plus and Esthetic) zirconia to obtain a favorable combination of pressure and particle type to produce optimum strength and optimize the bond produced. A protocol for mechanical treatment balancing strength of the type zirconia and bond to create the best bond with the least reduction in strength is the desired goal of this study. Methods: 420 sintered zirconia discs of Lava (Frame, Plus and Esthetic) were produced and the specimens of each material were randomly distributed into 14 groups (n=10). Half of these groups (210 specimens) were tested for shear bond strength while the remaining specimens were tested for biaxial flexural strength. One group in each of the seven groups served as the control which received no surface treatment. The experimental groups were particle abraded on one surface by 50 microns (u) alumina or glass beads at distance of 10mm for 10 seconds using three different pressures (15, 30, and 45 psi) according. After particle abrasion the specimens for shear bond strength test were sonicated for 2 minutes in water and the abraded surface thoroughly dried with compressed air for 30 seconds. A tube filled with Panavia SA cement was placed onto the surface and light cured from top and two sides for 10 seconds per surface (total 30 seconds). The specimens were water stored in an incubator at 37C for 24 hours and then placed into an Instron Testing Machine and loaded in shear until failure. Shear bond strength was calculated from the bonding area and the peak failure load. For the biaxial flexural strength testing, the thickness of each specimen with the same surface treatment as the bond strength specimens was measured by a digital caliber and placed in a fixture mounted on the Instron and loaded to failure. Biaxial flexural strength was calculated by applying a specific equation according to the biaxial flexural strength test (ISO standard 6872). Results: Significant differences were seen between surface treatments (p<.01), materials (p<.01) and their interaction (p<.01). Materials in each column with different letters are statistically different. Shear bond strength (MPa) Lava Frame Lava Plus Lava Esthetic Control 3.8±2.5c 4.6±1.1b 4±1.6c Alumina (15 psi) 12.7±6.6b 19.8±3.2a 30.5±5.2a Alumina (30 psi) 17.1±5.1b 19.2±8.3a 23.6±4b Alumina (45 psi) 28.2±7.1a 21.3±7.3a 23.4±5.7b Glass beads (15 psi) 2±0.4c 2.5±0.8b 2.6±0.4c Glass beads (30 psi) 1.5±0.2c 1.8±0.7b 1.6±0.5c Glass beads (45 psi) 1.9±0.5c 1.6±0.4b 1.4±0.3c With alumina particle abrasion, higher pressure produced higher bonds for Lava Frame and Lava Plus zirconia while the bond of Lava Esthetic declined with increased pressure. Biaxial flexural strength (MPa) Lava Frame Lava Plus Lava Esthetic Control 1235.6±130.2b 1363.9±17.4a,b,c,d 720.6±158.2a Alumina(15 psi) 1592.5±136.6a 1571.1±167.7a 594.3±37.3b Alumina (30 psi) 1584.4±166.6a 1463.6±187.6a,b,c 466.6±24.1c,d Alumina (45 psi) 1633.2±125a 1505.2±175.1a,b 409.3±33.4d Glass beads (15 psi) 1202.6±191.2b 1238.3±140.5c,d 651.9±109.8a,b Glass beads (30 psi) 1172±150.4b 1325.2±134b,c,d 598.6±70.8b Glass beads (45 psi) 1191±190.4b 1180.2±243d 576.5±54b,c The higher the pressure with alumina the lower the strength with 5mol% yttria containing Lava Esthetic zirconia Conclusions: Alumina produced a significantly better combination of bond strength while maintaining the biaxial strength of all zirconia than glass beads. The recommended pressure for surface treatment prior to bonding Lava Frame, Lava Plus and Lava Esthetic zirconia are 45 psi, 30 psi and 15 psi respectively

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