ABSTRACT
Context: Maxillary expansion is the mainstay therapy for maxillary transverse deficiency. There has been a constant search for the most effective yet biologically friendly method of maxillary expansion, alternatives being, slow, rapid and semi rapid. Aims: The purpose of this study was to explore the outcome of palatal expansion achieved using a removable plate and low continuous forces brought about by a semi rapid screw activation protocol. Settings and Design: Retrospective study. Methods and Material: Plaster models of 56 consecutive patients treated for maxillary expansion were obtained pre?treatment (T0), post?expansion (T1), and post fixed appliance treatment (T2). The radiographic images of the models were traced using Image J software. Linear and angular measurements were evaluated to measure transverse change. Statistical Analysis Used: Interclass Correlation Coefficient [ICC] and Dahlberg’s formula were used for reliability test. The differences in the mean values between the three duration groups [T0, T1 and T2] were analysed using Analysis of Variance (ANOVA). For multiple comparisons, a post hoc Tukey honestly significant difference (HSD) test was performed. Results: Significant increase in inter?molar, alveolar and palatal linear widths were observed from T0 to T1 with significant relapses from T1 to T2, with an overall net gain remaining at T2. Similarly, significant increases in all angular measurements were observed from T0 to T1 with significant relapses from T1 to T2 and an overall insignificant change at T2 as compared to T0. Conclusion: The appliance and protocol were effective in producing transverse expansion with minimal molar and alveolar tipping.
ABSTRACT
Background: Malocclusion in the vertical and sagittal planes is easy to observe whereas it is difficult to diagnose malocclusion in the transverse plane. There are yet no criteria defining a normal transverse occlusion. Aim: The aim of this study was to identify a ratio that defines a normal transverse occlusion. Study Design: This was a retrospective study. Materials and Methods: A total sample of 151 maxillary dental models (M = 55, F = 96) in the age range of 12-16 years were randomly selected, with 73 models in control group and 78 in the study group. All the models were mixed up and given to an operator for the measurement of intercanine width (ICW) and inter-palatal molar width (IPMW). Statistical Analysis Used : The data were statistically analyzed using SPSS software version 16.0. Chi-square test was performed to test the statistical significance difference between the groups at p ≤ 0.05. Results: Nearly 98.60% of normal arches were found to have an IPMW to ICW ratio of 1:1 ± 0.05. On further analysis, it was found that when IPMW ≥37.45 mm, then the case may be considered to have normal arches, and if the ratio between IPMW to ICW is 1.15:1 ± 0.05 or more and IPMW is <34.92 mm, then the case may be identified as deficient arch. Conclusion : The IPMW-to-ICW ratio can be used to differentiate deficient and normal arches. This hypothesis (Banker's hypothesis) is an easy and noninvasive method, using only two parameters, developed to help clinicians in identifying normal transverse dimension.