Efficacy of Nickel-Titanium Palatal Expanders

Abstract

Objective: Timely treatment of narrow maxilla by means of maxillary expansion during the primary or transitional dentition is recommended to reestablish optimal function in order to normalize dental, skeletal and neuromuscular growth. The aim of this study was to assess the amount of orthodontic and orthopedic expansion achieved in the maxilla and to evaluate cephalometrically the various postural changes in the maxilla and mandible with the use of nickel-titanium palatal expander. Materials and methods: A total of ten subjects, five males and five females were selected from a survey conducted on 2000 children in age range of 7 to 15 years, belonging to various schools. Their study cast, cephalograms and occlusal radiographs were used for the study. Maxillary intermolar width, maxillary intercanine width and mandibular intermolar width were measured on study cast using Vernier caliper. Certain measurements were done on the cephalogram and occlusal radiograph. The data obtained out of various measurements made on study casts, frontal, lateral cephalograms and occlusal radiographs at the pretreatment, postexpansion and postretention stages were statistically analyzed. All the observations were made by two observers. The interexaminer variability was calculated using t-test. The mean and standard deviations were calculated and student's t-test (paired) was applied to determine the amount of change, variability of change and significance of change, respectively. Results: A constant force exerted by nickel-titanium palatal expander had orthopedic effects in growing age group indicated by statistically increase in the maxillary width. The ratio of relative orthodontic to orthopedic effect with this appliance was 6:1. Consequent to maxillary expansion, there occurred a significant downward movement of the maxillae and downward and backward rotation of the mandible. There was opening of midpalatal suture during active phase followed by suture remineralization during the retention period. Conclusion: To conclude, a Ni-Ti expander brings about expansion by a combination of orthodontic and orthopedic effects by an increase in maxillary intermolar, maxillary intercanine and mandibular intercanine widths as also the opening of the midpalatal suture.