William J. Clark

Private practice, United Kingdom

Introduction: It has been an objective of the author for many years to design Fixed Twin Blocks, using pre-formed occlusal inclined planes as a guidance mechanism for mandibular advancement.

Objectives: For 15 years the author has evaluated Fixed Twin Blocks by clinical testing. A new design and protocol has evolved for effective mandibular advancement in treatment of Class II malocclusion.

Aims: This presentation illustrates the potential of Fixed Twin Blocks in dentofacial orthopedics and describes the design and clinical protocol to use the technique successfully in orthodontic practice.

Methods: CAD technology was used to design preformed occlusal blocks for direct fixation to the teeth, with inter-active inclined planes to guide the mandible forward to correct a distal occlusion.
After clinical testing the technique was refined and new appliances were designed with a protocol to simplify the fitting and management of Fixed Twin Blocks integrated with fixed appliances.

Results: Documented case reports of consecutively treated patients show how Fixed Twin Blocks influence the pattern of facial growth from mixed dentition to adult therapy. Subjects signed informed consent. Fixed Twin Blocks were combined with fixed appliances to integrate orthodontic and dentofacial orthopedic objectives in the management of severe hypo-divergent and hyper-divergent Class II malocclusion. Transverse and Sagittal TransForce appliances were used for arch development, followed by Fixed Twin Blocks and fixed appliances for detailed finishing. Arch development may also be integrated with Fixed Twin Blocks.

Conclusion: Fixed Twin Blocks represent the next logical step in combining orthodontic and dentofacial orthopedic therapy.