ABSTRACT
Nowadays, posterior cross bites are a relatively common malocclusion in societies. Basically, the first step in treatment abnormalities is recognition of it completely. The treatment of cross bites is not an exception from this rule. We must be aware of all of the skeletal and dental morphology of cross bite for treatment of it. The aim of this study was to compare the palatal width and depth between the patients with bilateral posterior cross bite and patients without posterior cross bite. In this case-control study, we considered the dental casts of 30 persons [22 girls and 8 boys] with ages ranging from 7 to 14 years with bilateral posterior cross bite as the case group and dental casts of 30 persons [22 girls and 8 boys] with ages ranging from 7 to 14 years without posterior cross bite as the control group. Dental parameters of palatal depth, maxillary intermolar width, maxillary interpremolar [or the first decidous molar] width and mandibular intermolar width were measured. These measurements were done by korkhaus instrument and student-t-test was used for analysis of data. None of the parameters were significantly different between girls and boys in both groups, except for mandibular intermolar width which was greater in boys in control [P=0.016] and case [P=0.01] groups. In both boys and girls with posterior cross bite, maxillary intermolar and interpremolar width was smaller, palatal depth was higher and mandibular intermolar width was larger compared with those without posterior cross bite [P<0.05]. Therefore in all cases with posterior cross bite compared with those without posterior cross bite, palatal depth was higher, mandibular intermolar width was larger, and maxillary intermolar and interpremolar width was smaller [P<0.001]. It can be concluded that in patients with bilateral posterior cross bite compared with patients without this type of malocclusion, palatal depth was higher and maxillary width was smaller