Survival analyses for MSI Pattern B. (A) Overall survival, (B) local relapse-free survival, (C) metastasis-free survival and (D) disease-free survival for different groups of MSI in pattern B. MSI, masticator space involvement. Classification pattern B: grade 0, grade 1 and grade 2 converted to PB0, grade 3 converted to PB1. Grades of masticator space involvement. Grade 0: without MSI; Grade 1: with medial pterygoid muscle involvement but without lateral pterygoid muscle involvement or infratemporal fossa involvement; Grade 2: with medial and /or lateral pterygoid muscle but without infratemporal fossa involvement; Grade 3: with infratemporal fossa involvement.