Читать книгу Fundamentals of Fixed Prosthodontics - James C. Kessler - Страница 82

A customized anterior guidance jig can be made for this articulator using a round-end incisal pin and a flat anterior table or an incisal cup. Acrylic resin or a light-cured material (Triad) is molded by the end of the incisal pin in the same manner that the anterior guidance is recorded for the other articulators. The mounted casts are examined on the articulator, and any nonworking interferences are removed. The articulator must be able to move freely with the anterior teeth in contact. If the guidance is inadequate, it is rebuilt to an optimum configuration with a diagnostic wax-up.

The incisal guide pin is raised at least 1 mm off the plastic incisal guide block in all excursions (Fig 5-70). The surface of the guide block is moistened with monomer. A half scoop of tray resin is mixed, and, while it is still free-flowing, a small amount is placed on the incisal guide. As the polymerizing resin becomes stiffer, more is added until there is about 6 mm (¼ inch) of it covering the guide block (Fig 5-71). The tip of the incisal guide pin and the occluding surfaces of the anterior teeth are lubricated with petrolatum. The articulator is closed to complete contact between the casts. The guide pin should sink into the soft acrylic resin (Fig 5-72). The articulator is moved through all excursions repeatedly, keeping the anterior teeth touching at all times (Fig 5-73). The pathways of all the movements will be imprinted by the tip of the guide pin in the acrylic resin as a permanent record (Fig 5-74). Movement of the casts is continued until polymerization is complete. The excess is removed.

Fig 5-75 To set the mechanical incisal guide, the casts are moved into a protrusive relationship. (a) The angulation of the table is increased to contact the pin. (b) The casts are moved into a right lateral excursion, and the left wing of the incisal table is raised. (c) The casts are moved into a left lateral excursion, and the right wing of the table is lifted to complete the recording.