After exfoliation of the primary incisors and eruption of the permanent incisors, the dentist has the opportunity of observing closely the beginning of occlusal changes. In several cases, alterations, such as lower anterior crowding, can be prevented and treated with proper follow-up. In the mixed dentition, one of the mechanisms for maintaining space and favoring dental alignment is to preserve leeway space before permanent second molar irruption. Among the devices with this function, the Nance lingual arch helps maintaining the position of the permanent mandibular molars and incisors after a premature loss of the primary canines. This paper describes the applicability of Nance lingual arch for preserving leeway space, thus contributing for correction of lower anterior crowding.