Generalized linear models for longitudinal data: an application to marginal fit of dental prostheses

Suely Ruiz GIOLO[1]

Reginaldo Salgado de CASTRO[2]

Josenita Ferreira do NASCIMENTO2

Edwin Fernando Ruiz CONTRERAS[3]

§    ABSTRACT: Titanium frameworks have been emerging to gather physical, chemical and mechanical characteristics that are very satisfying for implant prosthetic rehabilitation. The aim of this study was to evaluate: the laser-welding and spark erosion process in the decrease of unfitted frameworks margins of commercially pure titanium and titanium-aluminum-vanadium alloy; the effects of the ceramic firing cycle over the unfitted frameworks margins and; the marginal refinement by spark erosion after the simulation of firing cycles. Casting frameworks were made from a master die and divided in six groups: pure titanium + without treatment; pure titanium + spark erosion; pure titanium + laser welding; titanium-aluminum-vanadium + without treatment; titanium-aluminum-vanadium + spark erosion; and titanium-aluminum-vanadium + laser welding. After respective treatments, the frameworks were submitted to firing cycle (bonder, opaque, dentin and glaze) and marginal refinement by spark erosion. The marginal fit was measured after the study steps. Statistical results, obtained from longitudinal regression models under a generalized linear models approach showed that laser welding was the best treatment in all steps in the study. Similars unfitted frameworks margins were obtained from commercially pure titanium and titanium-aluminum-vanadium alloy.

§    KEYWORDS: Longitudinal data; dental prostheses; regression.



[1]Departamento de EstatÍstica, Setor de CiÊncias Exatas, Universidade Federal do Paraná, Caixa Postal 19081, CEP: 81531-990, Curitiba, Paraná, Brasil, E-mail: giolo@ufpr.br

[2] Universidade Federal do Paraná, Caixa Postal 19081, CEP: 81531-990, Curitiba, Paraná, Brasil, E-mail: regi.est@ufpr.br / josest@ufpr.br

[3]Faculdade Estadual de Odontologia de Londrina – FEOL, Universidade Estadual de Londrina – UEL, Caixa Postal 6001, CEP 86051-990, Londrina, PR, Brasil