Objective: To evaluate and compare the skeletal vertical and sagittal effects of the Hyrax expander in Class I, II, and III patients. Materials and Methods: One hundred and eighty-three patients (91 females, 92 males) with a mean age of 8.7 years and with maxillary bilateral cross-bite and maxillary hypoplasia were analyzed retrospectively. They were divided into three groups according to their skeletal class. Sixty-five patients were skeletal Class I, 55 were skeletal Class II, and 63 were skeletal Class III. For each patient a lateral cephalogram was obtained before treatment and at the end of the retention period. Changes in the groups during the observation period were calculated, compared, and statistically analyzed with a t-test. Results: In terms of vertical effects, a statistically significant increase in the anterior vertical dimension was observed only in Class III patients. No statistically significant changes were observed in the posterior vertical dimension in any of the groups. In terms of sagittal effects, in Class I patients the maxilla and the mandible moved forward, but not in a statistically significant way, and the ANB angle showed a statistically significant decrease, but its change was less modified. In Class II patients the maxilla moved forward, but not in a statistically significant way, while the mandible moved forward in all of the patients in a statistically significant manner. The ANB decreased, statistically improving the skeletal classification. In Class III patients the maxilla moved forward in a statistically significant manner; the mandible showed a downward and backward rotation, improving the skeletal classification. Conclusions: The data obtained in this study permit us to confirm that rapid maxillary expansion can be used in all of the skeletal classes with good vertical and sagittal results. (Angle Orthod. 2011;81:298-303.)

BackgroundThe aim of the present study was to assess the muscular variations at the electromyography (EMG) level for the anterior temporalis muscles and masseter muscles during treatment with Occlus-o-Guide® and Andresen activator appliances.MethodsEighty-two patients (35 males and 47 females) aged between 8 and 12 years (mean age, 10.5 ± 0.8 years) participated in the study. Fifty patients underwent treatment with an Occlus-o-Guide® and 32 patients with an Andresen activator. All patients underwent EMG examination using a Freely EMG (De Gotzen, Legnano, Italy) and surface bipolar electrodes when the appliances were worn for the first time (T0), and after 6 months (T1) and after 12 months (T2) of appliance use.ResultsStatistical analysis showed that both at T0 and T2, the percent overlapping coefficient (POC) of the anterior temporalis muscles was not statistically different between the appliance groups. At T0, the POC of the masseter muscles was significantly lower for the Andresen appliance as compared to the Occlus-o-Guide® (p = 0.02), while at T2 this significance was lost.ConclusionsAt insertion of an appliance, all patients show neuromuscular balance that does not correspond to orthognathic occlusion. Both appliances work by creating muscular imbalance. With the appliances in situ, EMG responses were generally analogous for the Occlus-o-Guide® and the Andresen activator; however, the imbalance was greater and the recovery of the orthological muscular balance was slower in patients under treatment with the Andresen activator as compared to those with the Occlus-o-Guide®.

BackgroundAlthough dental dilaceration disinclusion is an accepted treatment modality, few studies have evaluated the prognosis for dilacerated maxillary incisors and changes in clinical periodontal parameters still need to be demonstrated. The objectives of this study were to evaluate the prognosis and changes in clinical attachment level (CAL), probing depth (PD), and soft tissue recession (REC) for disincluded dilacerated maxillary incisors.MethodsTen impacted dilacerated teeth were scheduled for disinclusion. Five of them were disincluded with the apically repositioned flap technique and the other five with the closed eruption technique and brought into alignment with light orthodontic forces.ResultsAll the dilacerated teeth were disincluded as planned. CAL, PD, and REC were the same as natural teeth. Among the two surgical techniques, no statistically significant differences have been found.ConclusionThe choice to disinclude dilacerated central maxillary incisors reached the goals planned. Periodontal parameters obtained in a short- and long-term follow-up allow to affirm that the disinclusion of dilacerated teeth has a good survival rate.