the effects of cervical headgear with an expanded inner bow in the permanent dentition in this study the effects of cervical headgear chg use on the transverse dimension of the maxillary dental arch were evaluated in patients in the permanent dentition thirteen girls and 12 boys mean age 1341 052 years with a bilateral full cusp class ii molar relationship comprised the study group fifteen girls and 10 boys with a class i normal occlusion comprised the controls in the treatment group chg with an expanded inner bow was used for a mean period of 112 56 months the headgear was used for molar distalization and the force magnitude was 1961 cn after chg treatment the patients underwent nonextraction fixed orthodontic treatment for 141 25 months during this period the control group received regular dental checkups dental casts obtained at the beginning t1 and end t2 of headgear use and at the end of orthodontic treatment t3 and posteroanterior cephalograms taken at t1 and t2 were evaluated a students ttest was used for intergroup comparison at t1 t2 and t3 and a mannwhitney utest with a bonferroni correction for comparison of treatmentobservation changes at t2 intercanine 096 056 mm interpremolar 16 055 mm for the first premolar 174 065 mm for the second premolar and intermolar 231 075 mm widths increased while the distance between the intersection of the zygomatic process and the maxillary alveolar process on the right jr and left jl did not change fixed orthodontic treatment did not have any effect on any of the measurements with the intentional expansion of the inner bow of chg the amount of maxillary dental arch expansion achieved in the permanent dentition was statistically significant p 0017