Avaliação mecânica da utilização de placas e parafusos de titânio e absorvíveis para fixação de osteotomia sagital do ramo mandibular

Abstract

(Artigo 1 - Biomechanical evaluation of the use of absorbable plates for rigid fixation of sagital split ramus osteotomy) The rigid fixation of bone segments after mobilization has been purposes of study for many years. The use of plates and screws is responsible for a number of benefits to those who are used. Initial stability, fast and comfortable patient return to normal activities, good masticatory function and no need for maxillo-mandibular block for a long time; are some of the main advantages of rigid internal fixation. In addition to the titanium plates and screws can be used polyglycolic acid copolymers DL associated with the polylactide. This combination of features define plate and absorbable screw. Biocompatibility, less of genotoxicity, bioabsorption and easy handling are some characteristics of this material. However, similar initial stability to these plates still requires further studies. Therefore, the aim of this study is mechanically evaluate the stability of plates and absorbable screws in the technique of sagittal split osteotomy; the most widely used technique for jaw function in mandibular orthognathic surgery. Using a in vitro study, 15 hemimandibles (NACIONAL-JAÚ.SP) was evaluated with the design of the sagittal split osteotomy and fixed with different materials. Divided into 03 groups of five hemimandibles, the samples were submitted compression tests at different displacements. The displacements ranged from 1 to 5mm and the applied force was measured in Newtons (N). The results showed that there is a statistically significant difference in initial resistance when comparing conventional plates (Titanium) to absorbable plates. The conventional plates (titanuin) presented greater stability when compared to absorbable plates. (Artigo 2 - Biomechanical evaluation of the use trree diferent titanium plates for rigid fixation of sagital split ramus osteotomy) The rigid internal fixation of bone segments after mobilization has been purposes of study for many years. The use of plates and screws is responsible for a number of benefits to those who are used. Initial stability, fast and comfortable patient return to normal activities, good masticatory function and no need for maxillo-mandibular blocking for a long time; are some of the main advantages of rigid internal fixation. Therefore, the aim of this study is mechanically evaluate the stability of three different method fixation with plates in the technique of sagittal split ramus osteotomy (SSO); the most widely used technique for jaw function in mandibular orthognathic surgery. SSO was performed in 15 polyurethane synthetic mandible replicas. The distal segments were advanced 5mm and the specimens were grouped according to the fixation method: four-hole standard miniplate, two four hole standard miniplate and adjustable plate (Slider). Mechanical evaluation was performed by apllying compression loads to first molar using a Instron universal testing machine until a 5mm displacement of the segments. Compression loads were recorded in Newtons (N) and subjected to Statistical analysis was performed with the program R v. 3.5 with a significance level of 0.05. The data were represented by Mean, Standard Deviation, Minimum mediana and Maximum. To compare the force required to move each type of plate were used mixed Linear Models. The results showed that the stability of SSO was better accomplished using a double titanium plate and the adjustable plate demonstrated the worst resistance.