Correction of the borders and screw seat surfaces of implantretained frameworks by spark erosion: influence on the marginal misfit and on the strains transferred to abutments

Author(s)

Wagner Sotero Fragoso

• Document type: Doctoral Thesis
• Press: Piracicaba, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Faculdade de Odontologia de Piracicaba
• Defense date: 2007-04-05

Examining board members

Guilherme Elias Pessanha Henriques; Manoel Gomes Troia Junior; Osvaldo Luiz Bezzon; Marcelo Ferraz Mesquita; Mauro Antonio de Arruda Nóbilo

• Advisor: Guilherme Elias Pessanha Henriques

Abstract

The longevity of implant-retained rehabilitation is abbreviated when strains in the settings proceeding of marginal misfit have injured the bone-implant junction. The purpose of this study was to evaluate the marginal misfits and the abutments strains of cast implant-retained frameworks made from commercially pure titanium (CP Ti) by the one-piece casting technique, the laser welding technique and the over-analog casting technique and also evaluated the influence of spark erosion processes in the misfit and strain values. From a mandibular master cast, containing 05 conical abutment analogs, 10 frameworks were made from investment casts for over-analog casting technique. Plaster casts were used to originate 10 others frameworks gotten by one-piece casting technique and 10 frameworks by the laser welding technique. The marginal gaps were measured using a traveling microscope ('120) by means of one-screw test protocol. The strains (in gf) were identified by means of strain gauges arrangement in ½ bridge de Wheatstone attached to abutments and after the tightening of prosthetic screws at 10 Ncm. The marginal misfit and strain measurement were reproduced after spark erosion steps of screws seat base and cast cylinders fitting borders. Analysis of Variance and Tukey tests were used in the statistical analysis of the results (P<0.05). Following spark erosion steps, marginal misfit values were significantly reduced on the one-piece casting group and the strain values were significantly reduced on the one-piece casting group and over-analog casting group. It was concluded that the frameworks made from over-analog casting technique showed lesser marginal misfit and abutments strain than frameworks gotten by one-piece casting technique and laser welding technique; the spark erosion procedures were efficient in the decrease of marginal misfit and abutments strain of frameworks made from one-piece casting technique. There was positive correlation between marginal misfit and strain (AU)