Post-retention Development of Curve of Spee in Pre-adjusted Edgewise Appliance Cases, Its Correlation to Dentoskeletal Parameters: An In vitro Study

Background: Curve of Spee was first described by Ferdin and Graf Von Spee in 1890. The curve of Spee is an important characteristic of the mandibular dental arch. One of the most frequently encountered problems in the treatment of orthodontic patients is an excessive overbite. Deep bite has been found to be associated with abnormal mandibular function. Temporomandibular joint disorders also have potentially detrimental effects on mandibular development. Andrews advocated leveling the curve of Spee to aflat curve, in order to facilitate construction of an optimal occlusion and that a flat plane should be given as a form of over treatment. There is no reliable information currently available from the literature about the long-term stability of the curve of Spee and the factors influencing the same. The objective of this study was to assess the post-retention development of the curve of Spee and to evaluate the dental and skeletal parameters as predictors of its post-retention stability. Materials and Methods: Pre-treatment (Tl), post-treatment (T2) and post-retention (T3) dental casts and lateral cephalograms of 24 orthodontically treated patients having a mean age of 14.5 years were evaluated. The mean period of the study group after retention was up to 2.6 years (range = 1-5 years). Pre-treatment T1, post-treatment T2, and post-retention T3 casts and radiographs were measured. The data were tabulated and statistically analyzed. Results: A highly significant positive correlation was observed between the changes in the curve of Spee during treatment (T2-T1) and the net result after retention (T3-T2). This means that much of the treatment results remained stable at T3. However, slight change was noticed in curve of Spee’s depth during the time interval T3-T2. This finding was very negligible and was not statistically significant. Conclusion: The leveling of the curve of Spee during the treatment is a stable treatment objective on long term basis. There was a mild correlation existing between the curve of Spee and the different dental and skeletal parameters.

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