Evaluation of Andrews' six keys of normal occlusion in a sample of Iraqi adults in Baghdad city


Background: The Andrews’ six keys of normal occlusion contribute individually and collectively to the total scheme ofocclusion and, therefore, are viewed as essential to successful orthodontic treatment. The present research aims toevaluate the presence of the parameters of the Andrews’ Six Keys of normal occlusion in a sample of 100 Iraqi adultswith complete permanent dentition and clinically acceptable normal occlusion (Angle’s Class I) in Baghdad city.Their age range 18-25 years (60 males and 40 females).Materials and methods: Each patient was subjected to clinical examination and then study cast models were made,with their occlusal records. The measuring tools that have been used involved: Three-dimensional goniometer tomeasure crown angulation and inclination, Interlandi template to measure tooth rotation and digital calliper tomeasure curve of Spee.Results: The results that were obtained showed that the distribution of Andrews’ six key was achieved as follow: theInterarch relationship (key I) which is composed of seven items was achieved in most of models (72%); the Angulation(key II) was achieved in 67%; the Inclination (key III) was showed in less than half of the sample (41%); the Rotation(key IV) was achieved in 62%; the Interproximal contact (key V) was achieved in 57% and the Curve of Spee (key VI)was achieved in all models (100%).Conclusion: this study found that only 10% of the models presented with all six keys simultaneously. Whereas thehigher percentage (34%) was found with four keys and only one model presented with one key (1%).