History of functional therapy: From monobloc to twin-blocks appliances [Evoluzione storica e clinica della terapia funzionale: Dal monoblocco al bi-placca]

The aim of this study is to follow the historical development of functional appliances for the correction of skeletal Class II malocclusions, starting from different types of monobloc to the contemporary twin-blocks appliances. The Authors analysed theories and appliances proposed by many Authors who contributed to enrich functional "philosophy". The idea to split Andresen's monobloc into two removable plates, maintaining the advancement construction bite, has led to the development of the most used contemporary appliances: the Bite-jumping by Sander and the Twin-blocks by Clark. In these appliances any potential benefit of functional therapy is maintained, particularly as far as mandibular advancement and growth are concerned. The advantages of using a double-blocks appliance with respect to a monobloc consist of greater comfort for the patient, with a consequent greater compliance, of the possibility to add auxiliary elements and finally of a better control of the dentoalveolar effects during a functional treatment, with a reduced lower teeth mesial migration.