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Paulo César Borges

Publications and source records attributed to Paulo César Borges.

2 recordsLinked to original sources

Alternative methodology for flexural strength testing in natural teeth.

The use of natural teeth for performing in vivo , in situ and/or in vitro studies has been widely observed in the dental field. The mechanical behavior of teeth subjected to masticatory efforts is commonly used as a variable of response. In conditions of malocclusion, the most relevant component accounting for the integrity of the dental structure is non-axial (flexural). This force, while acting on a tooth in function in the oral cavity, generates a similar situation as that of a beam in balance supporting a load concentrated on its free extremity. Based on this configuration, a methodology has been developed to investigate the behavior of teeth subjected to this kind of efforts, taking into consideration specific aspects of the tested teeth, such as the transversal section area and the moment of inertia. For determination of the transversal section area an image analysis program was used. For assessment of the other variables, a C++ language program was implemented utilizing the Borland Compiler C++ Builder, version 1.0, for Windows (Borland International, USA). The applicability of the developed methodology is illustrated in this article using bovine teeth. Our findings indicate that more accurate data can be obtained with the application of this methodology and that it is suitable for studies testing the flexural strength of extracted teeth, as a variable of response.

Animals↗

Experimental force definition system for a new orthodontic retraction spring.

A new geometry of orthodontic retraction spring was experimentally studied through an electronic device (platform for measuring forces), using strain gauges that were adapted to cantilever beams. The sample consisted of 36 titanium-molybdenum springs, divided into three groups of 12 springs each. The springs were produced with different cross sections of 0.016 x 0.022 inch and 0.017 x 0.025 inch and with different angles between the extremities (120 degrees and 130 degrees). The springs were adapted to the platform in three different positions so that the force system developed by them could be known (horizontal forces, vertical forces, alpha-beta moments, and moment-to-force ratio M:F). The analysis of factorial variance and the Tukey honestly significant difference test were applied to verify the differences between the averages caused by three possible variation sources and the interactions between them. Regression analysis was also performed to obtain the spring rate. The results show the interactions between the three geometric variables, force magnitudes, and also the spring rates, which are compatible with the ones mentioned in the literature related to the subject. The spring rate was within the levels that are appropriate for clinical use (varying from beta = 33.1 gf/mm to beta = 43.9 gf/mm).

Dental Stress Analysis↗