AC failure was significantly worse with SPU dressings ( @/@ -LSB- @ % -RSB- ) than with BPU + SPU dressings ( @ / @ -LSB- @ % -RSB- ; P = @ ) , but not significantly different to TA + SPU ( @/@ -LSB- @ % -RSB- ; P = @ ) or SSD + SPU ( @/@ -LSB- @ % -RSB- ; P = @ ) .