Oral Health and Dental Management

Influence of veneering technique and coping-veneer ratio on fracture toughness of zirconia crowns

4^th Asia Pacific Congress & Expo on Dental and Oral Health

July 27-29, 2015 Brisbane, Australia

Fahim Vohra2, Mohsin Ali2 Ikmal Hisham Bin Ismail1 and Mohamed Ibrahim Abu Hasan1

Posters-Accepted Abstracts: Oral Health Dent Manag

Abstract:

Objectives: To investigate the influence of veneering technique and coping-veneer (C/V) ratio on the fracture toughness of implant retained zirconia crowns (ZrC). Materials & Methods: 32 Zirconia copings were divided into 0.5 mm and 1 mm thickness. Half of the 0.5 mm and 1 mm copings were veneered with an overall thickness of 3 mm and 4 mm. Half of all zirconia copings were veneered using build up (BU) and the remaining half using hot press (PR) method. Four metal ceramic crowns (MCC) with C/V ratio of 0.5/2.5mm and an overall thickness of 3 mm were used as controls. All specimens were cemented to titanium implant abutments and tested using micro indenter. Crack length, hardness and surface roughness for all specimens was evaluated which was then utilized to calculate fracture toughness. ANOVA was utilized to analyze the results. Results: C/V ratios of 0.5/2.5 and 1/3.5 showed significantly better (p=0.001) fracture toughness as compared to C/V ratios of 1/2 and 1/3 for the bilayered implant retained ZrC. MCC (0.5/2.5) showed significantly higher fracture toughness (p= 0.01) as compared to ZrC of similar C/V ratio. Fracture toughness (KIC) values for PR and BU veneers on zirconia copings of compatible C/V ratios were statistically comparable (p=0.409). The mean surface roughness (sa) of all specimens was statistically similar (0.2290 �0.0372). Conclusion: Within the limitations of this study, fracture toughness of bilayered implant retained ZRC and MCC was improved by increasing thickness of veneering ceramic. Ceramic veneering technique did not influence fracture toughness of bilayered ZRC crowns.