In Vitro Biomechanical Evaluation of Modified Plating Techniques for Bilateral Sagittal Split Ramus Osteotomy in Mandibular Advancement

Abstract

The aim of this study was to compare the biomechanical properties of modified plate techniques using a newly designed three-dimensional test model after sagittal split ramus osteotomy. Fifteen synthetic polyurethane mandibular replicas were used and divided into 3 groups. Self-tapping 6-mm titanium screws with an outer diameter of 2.0 mm and private designed plates produced by 316-L stainless steel were used in the study. After the osteotomy, the distal part was advanced by 5 mm. The jaw models were placed to the three-dimensional test model designed by the authors, and the Instron Lloyd LRX device was used to apply a double-sided tensile force from the mandible angulus region of each group. Resistance forces that caused a displacement of 1.5 and 3 mm were recorded with the Instron program. The mean (SD) of the 3 groups were calculated using analysis of variance and the Tukey test. The results were compared statistically, with values of P < 0.05 determined as statistically significant. On the basis of the results of the Tukey comparison within the groups, there was a statistically significant difference between groups 1 and 2 and between groups 1 and 3 at both 1.5- and 3-mm displacement (P < 0.05). No significant difference was observed between groups 2 and 3 (P > 0.05). This test model was able to identify the most appropriate plate type of 3 different modified plate techniques after sagittal split ramus osteotomy.

Biomechanical Evaluation of a New Fixation Method for Stabilization of Sagittal Split Ramus Osteotomy After Mandibular Advancement

“…The addition of 2 vertical connecting bars at the ends of this Z-shaped design did not result in more stability. 16 In contrast to our study, these studies did not compare this with a fixation method using 3 bicortical screws in an inverted-L pattern, which is considered to be the "gold standard" regarding rigidity in mandibular advancements of up to 10 mm. 4,[15][16][17] Because of this classification, the authors feel that when focusing on stability, a 3 bicortical screws fixation should always be used as a benchmark and control when evaluating new methods of fixation.…”

“…That is why, similar to our study, other studies have also utilized the in vitro biomechanical method in order to test the mechanical resistance of new osteosynthesis materials. 11,[14][15][16] In this study we simplified the model to an hemimandible and used a cantilevered beam model in mimicking masticatory function. Other biomechanical studies have used whole polyurethane mandibular replicas, in which more complex biomechanical models were used in mimicking masticatory function.…”

“…Other biomechanical studies have used whole polyurethane mandibular replicas, in which more complex biomechanical models were used in mimicking masticatory function. 4,12,16 Although the strive for closer proximity to human anatomy in these models could be encouraged, the results of all biomechanical studies cannot directly be extrapolated to clinical circumstances. As of a financial perspective, the costs for materials in biomechanical research with complete mandibles would be doubled with the same number of samples.…”

“…It is thought that connecting the 2 miniplates could provide additional stability. 4,15,16 A gridplate may also be useful in minimizing post-operative instability in the case of larger mandibular advancements. In the recent literature, various new designs of gridplates have been compared with other fixation methods.…”

Biomechanical Loading Evaluation of Unsintered Hydroxyapatite/poly-l-lactide Plate System in Bilateral Sagittal Split Ramus Osteotomy

“…Since it is difficult to obtain this material due to legal and ethical reasons, such in vitro alternative models are controversial, as they cannot exactly reproduce the function of the human bone [ 28 ]. In our study, synthetic jaw models were used because they are easy to obtain, inexpensive, allow for standardization [ 28 , 29 ], and are amenable in evaluating the mechanical characteristics of fixation materials prior to their application in humans [ 27 ].…”