Objective: To evaluate reverse-sequencing chewing cycles (RSCC) and their kinematic parameters on both sides before and after correction with the Function Generating Bite (FGB) appliance. Materials and Methods: Forty-seven patients, 8.3 6 1.1 (mean 6 SD) years of age, with unilateral posterior crossbite (35 on the right side, 12 on the left side) and 18 age-matched controls (9.1 6 0.8 years) were selected for the study from the orthodontic division of the University of Turin, Italy. The crossbite was corrected in all patients using FGB, and mandibular motion was recorded with a kinesiograph K-7 (Myotronics, Tukwila, Wash), during chewing on both sides of a soft and a hard bolus before and after correction. Results: After correction, the percentage of RSCC significantly decreased for soft and hard (P , .001) boluses and fell within the normal range for 75% of the patients. The indices of the chewing pattern (closure angle, axis, maximum lateral excursion) significantly improved (P , .001), becoming symmetric between sides. Conclusions: The results of this study showed that the functional appliance, FGB, was able to lower the percentage of RSCC significantly, bringing them back to the normal range in 75% of cases, and to improve the kinematic parameters that become symmetric between sides. (Angle Orthod. 2017;87:871-877.)

Objectives The objective of this study is to confirm the developmental origin of the enamel organ and evaluate the role of E‐cadherin in tooth development by conditional deletion in the oral epithelium and its enamel organ progeny. K5‐Cre;ROSA26 compound mice were included in this study in order to confirm the oral epithelial origin of the enamel organ, as well as of the action of the K5‐Cre transgene in ablating E‐cadherin in the enamel organ. K5‐Cre;Ecadfl/fl knockout mice were included to evaluate the effects of the conditional E‐cadherin ablation onto tooth development. Material and Methods K5‐Cre transgenic mice were crossed into the ROSA26 reporter mouse to trace the cell fate of the oral epithelium and its progeny in vivo. Moreover, K5‐Cre mice were crossed into the Ecadfl/fl mice to produce K5‐Cre;Ecadfl/fl compound mouse, as well as K5‐Cre;Ecadfl/+ and Ecadfl/fl littermate controls. These litters were euthanized at postnatal day P2 to study the effects of conditional E‐cadherin ablation in vivo. Results The K5‐Cre;ROSA26 compound mouse demonstrated that the origin of the enamel organ and the structures thereof are of oral epithelial origin. Furthermore, using the K5‐Cre;Ecadfl/fl compound mouse, we determined that conditional ablation of E‐cadherin in the oral epithelium, and its progeny, results in dental anomalies involving elongation of the molar root, shrinkage of the pulp space, and alterations of the periapical area, including cementum hyperplasia. The K5‐Cre;Ecadfl/fl mice also displayed a smaller overall stature compared with heterozygotes and wild‐type littermates. Conclusions E‐cadherin is important in tooth development, including the formation of enamel, the crown, pulp space, and the roots.

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