A comparative study to evaluate the effectiveness of lateral cephalogram and study cast to measure anteroposterior anchorage loss with preadjusted edgewise appliance

Objective: Measurement of anchorage loss is an essential part of assessing the orthodontic treatment. It can be assessed on the lateral cephalogram or on study models. The purpose of the present study is to compare the mean horizontal molar movement or anchorage loss relative to the palatal rugae landmarks on study models with that of cephalometric superimpositions in maximum anchorage cases and to concur whether only one record (study casts or cephalogram) could suffice for the evaluation of the anchorage loss. Materials and Methods: A power analysis was performed to determine the sample size needed to detect a 1.0-mm difference in tooth movement with the effect size of 0.5 at a confidence level of 90%, to consider the dropouts thirty maximum anchorage patients requiring first premolar extraction as part of their treatment plan were selected by consecutive sampling. Mean horizontal movement of molars was calculated on lateral cephalogram and study cast records after alignment and leveling. Statistical Analysis: Paired t-test was performed to compare the mean values of anchorage loss measured on lateral cephalogram and study model. Results: The results showed that there was no statistically significant difference in measurement of anteroposterior anchorage loss with either lateral cephalogram or study cast (p – value 0.554). The mean horizontal molar movement measured on lateral cephalogram was 2.32 with SD of 1.77 and mean horizontal molar movement measured on study cast was 2.09 with SD of 1.22. Conclusion: The present study shows that the measurement of anchorage loss on study models is equally reliable as that on the lateral cephalogram. Thus, study models presents as an alternative to the measurement of anteroposterior anchorage loss.