Changes in mechanical properties of poly-l-lactic acid mini-plate under functional load simulating sagittal splitting ramus osteotomy

Abstract

The purpose of this study was to investigate how the characteristics of a poly-L-lactic acid mini-plate changed with dynamic loading in an environment with hydrolytic degradation.We prepared a mandible osteosynthesis model with specimen poly-L-lactic acid mini-plates to simulate sagittal splitting ramus osteotomy. The model was then subjected to dynamic loading, and changes in specimen shape and surface quality were observed. Specimen bending strength was then measured, and degree of hydrolytic degradation estimated. Statistical studies included an analysis of variance (ANOVA).Neither dynamic loading nor degree of load clearly affected degree of hydrolytic degradation. The specimens maintained their original shape and bending strength for up to 4 weeks with dynamic loading of 40 N or less in an environment with hydrolytic degradation. However, at 8 weeks, under the same conditions, the specimens showed cracks or fractures, or both, together with a clear decrease in bending strength.The results suggest that dynamic loading causes cracking in a poly-L-lactic acid mini-plate, and that growth of those cracks decreases bending strength over time, leading to fatigue fracture.--2

Management of pediatric mandibular fractures using bioresorbable plating system – Efficacy, stability, and clinical outcomes: Our experiences and literature review

“…22 The absorption happens in two phases: hydrolysis and fragmental metabolization. 23 Hydrolysis occurs when body fluids enter the implant and chemically react with the polymer and break the polymer chains. Fragmental metabolization occurs as the polymer continues to fragment until single lactic acid molecules are finally metabolized in the liver into carbon dioxide and water.…”