Int J Prosthodont 29 (2016), No. 1 12. Jan. 2016
Purpose: Published literature on mandibular movements is extensive, but it lacks scientific robustness and is understandably controversial. This preliminary study recorded and assessed characteristic forms and condylar path inclination patterns during mandibular protrusion and opening in completely edentulous subjects. These features facilitate the setting of condylar guidance records on articulators.
Materials and Methods: A convenience study sample of 60 asymptomatic edentulous patients (aged 58 to 74 years) was provided with new complete dentures. After localizing hinge axis movement, sagittal condylar paths were recorded and analyzed with an electronic axiograph (AXIOCOMP, SAM).
Results: Protrusion and opening movement patterns showed completely different characteristics. During protrusive movement, condylar paths showed a sinusoidal pattern (51%), and condylar inclination was low at 1 mm (32.2 degrees) and 2 mm (40.4 degrees). Conversely, during the opening movement, the most frequent pattern found was the classical convex form (57%). Inclinations were higher: 50.8 degrees at 1 mm and 50.7 degrees at 2 mm.
Conclusions: Completely edentulous subjects present radically different sagittal condylar paths when compared with dentate patients. These differences result from alterations in disc-condyle relationships and morphologic changes in bone structure. No link was observed between condylar paths recorded in protrusion and opening movements. Consequently, condylar guidance for articulators should be set using recordings from protrusive movements.