Evaluation of the marginal and internal fit, resistance to fracture after thermomechanical cycling and tensions in the implants by correlation of digital images in fixed partial dentures on implants with abutments and copings in zirconia with different CAD/CAM systems

Author(s)

Francielle Alves Mendes

• Document type: Doctoral Thesis
• Press: Ribeirão Preto.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Ribeirão Preto (PCARP/BC)
• Defense date: 2015-06-02

Examining board members

Ricardo Faria Ribeiro; João Neudenir Arioli Filho; Flávio Domingues das Neves; Mauro Antonio de Arruda Nóbilo; Ivete Aparecida de Mattias Sartori

• Advisor: Ricardo Faria Ribeiro; Flávio Domingues das Neves

Abstract

Considering the growing aesthetic requirements, the development of zirconia and the increase of CAD/CAM technology, the aim of this study was to evaluate the marginal and internal fit, tensions in implants and fracture resistance after pressing porcelain and thermomechanical cycling in FPDs on implants with abutments and infrastructure in zirconia with two CAD/CAM systems (Neodent digital -Neodent and Lava - 3M ESPE) compared with the conventional method (n = 10). The marginal and internal fit was analyzed by a computerized microtomograph (microCT). Each prosthesis was scanned and the files were processed using the NRecon and CTAN software. Dataview program was used for the assessment of the measures. To carry out the thermomechanical cycling, prostheses were placed in mechanical fatigue machine for chewing and 120 N load was applied with a tip that simulates the antagonist occlusion simulating 2,000,000 cycles. During the test, the prostheses were kept in distilled water and thermocycled with temperatures between 5°-55° C. Digital image correlation analysis was performed to check the load transfer by implant-supported restoration. Five models were selected from each of the CAD/CAM systems and an antagonist and a load of 250 N was applied, with 0.1 mm/min speed using a universal testing machine. The fracture resistance was verified with force applied perpendicular to the long axis of the prosthesis, at pontic, until there were no more fracture resistance. After this test was evaluated the relationship between the components of the prosthesis in a scanning electron microscope (SEM). The statistical analysis showed significant difference in abutment-implant fit of molars between Lava and ZirNeo, Lava and control groups (p=.008). For vertical and horizontal fit there was no significant difference (p>.005) before and after pressing and thermomechanical cycling. The axial internal gap was significantly different before and after for molar ZirNeo groups (p<.001). The occlusal internal fit was significantly different to the PM of TiNeo and Control, and the molars of Lava and ZirNeo (p<.005). There were significant difference for tension in the cervical region of the molars of ZirNeo and Lava (p=.015) with higher values for the Lava group. TiNeo group had higher resistance to fracture than others (p=.022). The relationship between the prosthesis components remained positive for all groups. The results of this study showed that the pressing of porcelain and thermomechanical cycling did not influence the results of marginal gap and improved internal fit. The zirconia group machined by Neodent digital system had higher concentration of tension in the cervical and may have greater bone loss in this region. TiNeo group was the most resistant to fracture. Between the zirconia milling by Neodent digital or Lava system, the Lava system distributes better strain throughout the implant, but had greater internal fit values. Between milling titanium or fabricate the prosthesis by the conventional system, better milling. (AU)

• FAPESP's process: 12/08003-6 - Evaluation of marginal adaptation and internal, of resistance to fracture after thermo-cycling and mechanical implants tensions by digital image correlation in partial prosthesis implant fixed with pillars on zirconia with different CAD/CAM systems
• Grantee: Francielle Alves Mendes
• Support Opportunities: Scholarships in Brazil - Doctorate