Influence of the implants inclination on the accuracy of the working cast

Wirley G Assunção,Valentim A R Barão,Juliana Aparecida Delben,Juliana R P Jorge,Érica A Gomes

doi:10.14295/bds.2007.v10i2.334

Abstract

The aim of this study was to evaluate the influence of the implants inclination on the accuracy of the working cast obtained by two different pouring techniques. A metallic matrix containing two implants, positioned at 90 and 65 degrees in relation to the alveolar ridge, was submitted to the direct transfer impression technique. In CP group (conventional pouring - n=10), the impressions were poured with dental stone type IV using the conventional technique. In EP group (experimental pouring - n=10), the analogs were embraced with latex tubes before the first pouring. After sixty minutes, these tubes were removed and the space was filled with the dental stone. The metallic matrix (control group) and the replicas were evaluated regarding the implant/analog inclination and the vertical misfit between a framework and the implants/analogs. The data were tabulated and analyzed using analysis of variance (ANOVA) and Tukey test at the 0.05 level of significance. Regarding the analog inclination, both experimental groups differed statistically (p<0.05) from the control group only in relation to the leaning analogs. Results demonstrated significant difference (p<0.05) between the control group and the experimental groups when the reading of the vertical misfit was accomplished in the perpendicular implant/analog with the retention screw in the leaning implant/analog and between the control group and the EP group in the opposite situation. Considering the inclination, perpendicular implants produced more accurate casts independently of the plaster pouring technique.

Highlights

Dental implants are an efficient alternative to oral rehabilitation due to the osseointegration that provides an unity among bone, implant and prosthesis[20]
These factors are relevant to provide an adequate distribution of the stress through the implant-bone interface[12,21,22] even though it is impossible to measure the biological capacity of each individual according to different degrees of misfit[8]. This fact is a result of an accurate working cast that shows characteristics such as position and inclination of the implants by the same way they are in the mouth. This accuracy is related to the impression technique[3,9,15,19,24], the dimensional stability and good reproducibility of the impression material[10,26] and the careful plaster pouring considering its expansion[14,23]
The matrix was submitted to the direct transfer impression technique with splinted impression squared copings through a dental floss scaffold covered with self-curing acrylic resin (Duralay; Reliance Dental MFG Company, Worth, IL, USA)

Summary

Introduction

The long term success of the treatment is related to the effective patient home care[17], the appropriate alignment of the implants and their position of implantation[25] and the passive fit of the superstructure to the abutment or the implant These factors are relevant to provide an adequate distribution of the stress through the implant-bone interface[12,21,22] even though it is impossible to measure the biological capacity of each individual according to different degrees of misfit[8]. This fact is a result of an accurate working cast that shows characteristics such as position and inclination of the implants by the same way they are in the mouth. This accuracy is related to the impression technique[3,9,15,19,24], the dimensional stability and good reproducibility of the impression material[10,26] and the careful plaster pouring considering its expansion[14,23].

Objectives

Methods

Conclusion