Stress Analysis in Maxillary All-On-Four Model

Abstract

The aim of this research was to evaluate the load distribution in tilted distal implants used in the all-onfour system. Two implant schemes were used. In both, two vertical anterior implants and tilted posterior implants were installed, one group with an angulation of 15º and another with an angulation of 35º. The implants were installed together with a bar binding them all in a photoelastic model obtained from a replica of an edentulous maxilla. In this model, loads were produced in the sector of the bar cantilever, the abutment of the tilted implants and over the four implants using devices specially designed for this purpose. The bands were recorded with a digital camera, and the qualitative and quantitative analyses were carried out by means of student's t-test and the Mann-Whitney test in Biostat v. 5.0, considering a level of p<0.05 to establish a statistically significant relation. In the qualitative analysis, the implant with 35º presented the greatest amount of stress on the cantilever forces at cervical level. The quantitative studies showed fewer differences in all aspects assessed, although significant differences were observed between the two systems when loads were applied at cantilever level. It can be concluded that there are minimal differences in the stress distribution when comparing implants with angulations of 15º or 35º. However, there is a greater concentration of stress at the cervical level in implants tilted to 35º.

Clinical and biological analysis in graftless maxillary sinus lift

“…Proposed options for maxillary sinus lift include zygomatic implants and the use of angulated implants, which can adapt to atrophy of the posterior maxillary sector 5 6 . However, the maxillary sinus lift continues to be a viable technique with high success rates.…”