permanent molar 71 in such an arrangement for correction of misaligned incisors 72 they must be anchored to the permanent molars 71 which are three teeth away in the back of the mouth bypassing the deciduous canine 75 and deciduous molars 74 at the present time orthodontic treatment of any mixed dentition case both permanent and deciduous teeth present involves the use of a u201c two by four u201d 2 u00d7 4 appliance the 2 u00d7 4 designation refers to the two permanent molars 71 and four permanent incisors 72 of a mixed dentition dental arch used for the placement of a bracket assembly 10 a typical 2 u00d7 4 appliance is shown on mixed dentition upper and lower dental quadrants in fig1 the 2 u00d7 4 appliance 77 consists of bracket assemblies 10 attached to permanent molars 71 permanent incisors 72 and archwire 66 engaging bracket assemblies 10 on each quadrant this arrangement relies on the permanent molars 71 as anchors to correct the misaligned permanent incisors 72 unfortunately the permanent molars 71 do not provide adequate anchorage for alignment of the permanent incisors 72 even more troubling for the patient the 2 u00d7 4 treatment may cause misalignment problems in the permanent molars 71 themselves that otherwise wouldn 39 t have occurred since the archwire 66 in a 2 u00d7 4 appliance system has to by pass the three non bracketed deciduous molars 74 and.