[Biomechanical effect of 2 anchorages on maxillary protraction with cleft lip and palate: a finite element analysis]

To establish cranio-maxillary complex finite element models (FEMs) in cleft lip and palate (CLP) patients with miniplate and tooth-borne anchorage, and to investigate the biomechanical effects on maxillary protraction.

The protracting process was simulated on FEMs established from a male patient's cone beam CT (CBCT) data to analyze the displacement and stress from different appliances.

Four FEMs of unilateral cleft lip and palate (UCLP) or bilateral cleft lip and palate (BCLP) patients' cranio-maxillary complex with MA and TA were established. The maxillary arch on both sides of the cleft moved towards the cleft side during protraction, which was more obvious in the miniplate anchorage three-dimensional finite element models(FEM-MA) than the tooth-borne anchorage three-dimensional finite element models (FEM-TA).The amount of forward, downward displacement of the inferior orbital rim, paranasal area and middle maxilla point in the FEM-MA was larger than that in the FEM-TA, while the amount of forward displacement of premaxilla and upper canine in the FEM-TA was larger than that in the FEM-MA. The FEM-MA exhibited an orthopedic effect with more favorable stress distribution on the middle maxilla point while the FEM-TA showed a dentoalveolar effect with prominent stress distribution on the upper canine point. In addition, the FEM-MA showed a larger stress distribution area and sutural stress value than did the FEM-TA. The UCLP models showed an asymmetric pattern in stress distribution and displacement, which was larger on the cleft side than that on the non-cleft side. The amount of displacement of premaxilla in the BCLP models was smaller than that in the UCLP models.

The established models have high geomagic and biomechanical similarities. It would be more advantageous to obtain more aesthetic outcomes and better stability using the miniplate anchorage.