Mechanical and Thermal Cycling Effects on the Flexural Strength of Glass Ceramics Fused to Titanium

Abstract

This study evaluated the effects of mechanical and thermal cycling on the flexural strength (ISO 9693) of three brands of ceramics fused to commercially pure titanium (cpTi). Metallic frameworks of 25×3×0.5 mm dimensions (N＝84) were cast in cpTi, followed by 150-μm aluminum oxide airborne particle abrasion at a designated area of the frameworks (8×3 mm). Bonder and opaque ceramic were applied on the frameworks, and then the corresponding ceramic (Triceram, Super Porcelain Ti-22, Vita Titankeramik) was fired onto them (thickness: 1 mm). Half of the specimens from each ceramic-metal combination were randomly tested without aging (only water storage at 37ºC for 24 hours), while the other half were mechanically loaded (20,000 cycles under 10 N load, immersion in distilled water at 37℃) and thermocycled (3,000 cycles, between 5-55℃, dwell time of 13 seconds). After the flexural strength test, failure types were noted. Mechanical and thermal cycling decreased the mean flexural strength values significantly (p<0.05) for all the three ceramic-cpTi combinations tested when compared to the control group. In all the three groups, failure type was exclusively adhesive at the opaque ceramiccpTi interfacial zone with no presence of ceramic on the substrate surface except for a visible oxide layer.

Influence of Thermal Cycles Number on Bond Strength of Metallic Brackets to Ceramic

“…Besides, the difference in the thermal expansion coefficients of both materials may cause adhesive loss from temperature variations (7). In orthodontics, the number of thermal cycles varies from 500 to 6,000 (5,8,10,11).…”

“…It is most recommended because it reproduces the stresses caused at the bonding resin/enamel and bonding resin/bracket interfaces during alignment, leveling and sliding movements in the orthodontic treatment. The durability may be influenced due to heavy forces produced by archwire (2), the action of water-saliva storage (6), thermal and mechanical cycling test to simulate the oral conditions prior to mechanical tests (5,7).…”

Effects of thermal cycling and surface roughness on the Weibull distribution of porcelain strength

“…Besides, temperature changes in the mouth have a negative effect on promoting crack growth over a prolonged period. By the same token, reports have emerged on the effects of thermal cycling on the flexural strength of metal-ceramic complexes 5,6) , marginal adaptation of metal-ceramic restorations 7) , and fracture strength of resin-bonded, all-ceramic fixed partial dentures 8) . However, information is scarce on the effects of thermal cycling on dental porcelain.…”

Influence of different treatments of the ceramic surface and thermal cycling on the bond strength of brackets to ceramic

“…The thermal cycling test has been recommended and used to verify if temperature changes may influence the reduction of bond strength values between the ceramic surface, bonding materials and brackets 2 . Previous studies showed that the reduction of the bond strength could be due to continuous action of the water on the ceramic-bonding materials-brackets interface with hydrolytic degradation of the components 24 . In addition, different thermal expansion coefficients and abrupt temperature changes of bonding materials can produce thermal stresses at the interface and decrease the bond strength 24 .…”

“…Previous studies showed that the reduction of the bond strength could be due to continuous action of the water on the ceramic-bonding materials-brackets interface with hydrolytic degradation of the components 24 . In addition, different thermal expansion coefficients and abrupt temperature changes of bonding materials can produce thermal stresses at the interface and decrease the bond strength 24 .…”