the best time to use a Bonded R.P.E. with Lap Springs is with a mixed dentition patient. Besides correcting a crossbite, it has been shown that expansion of the maxilla during the early mixed dentition stage may lead to a spontaneous correction of other occlusal disharmonies. For example, expansion of the upper arch in a skeletal Class II can allow the mandible to come forward on its own. Adding anterior lap springs resolves anterior crowding -- especially important when the anteriors are in an end-to-end or mild crossbite. Springs can be adjusted intraorally (using three-prong pliers). Note: A Bonded R.P.E. is not recommended for patients who are in the late stage of mixed dentition. Loose or exfoliating teeth will greatly compromise appliance anchorage.