The borderline patient and conservative treatment in the late mixed dentition

1. The possibilities for successful conservative treatment of mild lower arch length deficiencies (2 to 5 mm.) are explored for twenty growing patients in the late mixed dentition. 2. Methods of case selection and treatment particulars are presented. 3. Each patient should be considered as an individual with regard to cephalometric norms for the optimal position of the incisors, in determining the size of the leeway space at the lower second deciduous molar position, in evaluating the feasibility of distal uprighting the lower first permanent molars, and in formulating a reasonable treatment plan. 4. It is postulated that oversized lower second deiduous molars may be an etiologic factor in some mild lower arch length deficiencies (r = 0.4; P less than 0.05). 5. The amount that the lower first premolars and lower canines can be distally retracted into the leeway space in these conservatively treated cases is directly related to retraction of the lower incisors (r = 0.7; P less than 0.01). In the present cases uprighting the lower incisors allows the upper teeth to be treated well and together this enables functional and esthetic improvement and tooth stability.