The Alveolar Ridge Splitting Technique on Maxillae: A Biomechanical Human Cadaveric Investigation

Abstract

The alveolar ridge splitting technique (ARST) offers an alternative to classic ridge augmentation techniques for successful insertion of dental implants. However, the buccal lamella is at risk of fracturing during ARST distraction. To better understand the fracture mechanisms and displacement limits of the split lamella, this study conducted biomechanical tests on human cadaveric maxilla specimens having extremely atrophied alveolar ridges treated with ARST. A total of 12 standardized alveolar splits were prepared on the maxillae of 3 elderly female donors using an oscillating piezoelectric saw. Mimicking the surgical distraction process of the lamella, each split was tested to failure using a dental osteotome attached to the crosshead of an electromechanical testing system. All specimens were scanned by means of high-resolution peripheral quantitative computed tomography prior to and post testing to evaluate split geometries and failure modes. Split stiffness, failure force, and displacement were $27.4\pm 18.7$  N/mm, $12.0\pm 8.4$  N, and $0.97\pm 0.31$  mm, with no significant differences between anatomical sides and split locations ( $p\ge 0.17$ ). Stiffness correlated significantly with failure force ( $R^2=0.71$ , $p<0.01$ ). None of the alveolar split widths correlated significantly with the outcomes from biomechanical testing ( $p\ge 0.10$ ). The results suggest that simple geometrical measures do not predict the allowed extent of lamella distraction prior to failure. More sophisticated methods are required for surgical planning to optimize the ARST outcomes. Still, the present study may advocate a clinical protocol for the maxilla where the implant site is prepared directly after osteotomy setting and immediately before full lamella dislocation, when the lamella is still stable, resistant to mechanical stress, and bone loss caused by the abrasion of the burr is minimized.