The study evaluated two oral devices.
(2) An FGS covering the teeth with a flat posterior support zone was inserted on the mandibular arch; the angulation of the lateral and anterior guidance was minimal (as flat as possible) but steep enough to disocclude all premolars and molars in any dynamic mandibular activity (Fig. 1b
). Maxillary and mandibular arch impressions were obtained with alginate in an individualized tray and models were cast in artificial plaster type 4 dental stone (Fujirock EP, GC, Leuven, Belgium). The centric relation, the reference position (RP) was obtained with a bite plate (light curing custom tray material, Supertec, DMG, Hamburg, Germany) and optimized adaptation to the maxillar dentition was implemented using pattern resin (acrylic resin for patterns, Pattern Resin LS, GC, Tokyo, Japan). The bite registration of the mandibular dentition (3/7) was preserved with Alu-wax (accurate bite registration wax, Alminax, Kemdent, Swindon, UK). A kinematic face bow (Condylograph, Gamma Dental) was used to mount the models in an adjustable articulator (Reference SL, Gamma Dental) with a standardized verticalization of 7 mm on the incisal pin. The BCs (analytic foil 0.1 × 125 mm, Brux Checker®, Scheu Dental Technology, Iserlohn, Germany) were based on the two models and each was used for two nights separately in the maxilla and mandible according to previous reports [17
]. The FGS (cold curing denture base material, Pro Base Cold, Ivoclar, Schaan, Liechtenstein) was fabricated using a wax-up method and pressed on the mandibular model. It was inserted and adjusted in the patient’s mouth without any manual guidance by the operator while the patient was placed in a sitting position in a dental chair. Uniform occlusal contacts were created to hold the Shimstock foil (Shimstock foil 8 μ, Hanel, Langenau, Germany) on the lingual cusps of the molars and the premolars against the splint to provide reliable static stability. The anterior teeth and the cuspids were lightly touching the splint but not holding the Shimstock foil. Lateral movements were guided by the tips of the maxillar canines; protrusive movements were guided by the incisal edges of the maxillar front teeth against a horizontal anterior ramp of the FGS. In any excursion, dynamic interference in the molars and the premolars was eliminated. The same operator (GR) provided the treatment and each patient was given the same instructions. The patients were asked to wear the splint continuously for 24 h except when eating and when cleaning the teeth. After 7 days in the following session, the splint was adjusted using the described adjustment procedure. To obtain reproducible stability for the FGS with no change from one weekly appointment to the next 2–5 sessions were necessary.