The U-Shaped major connector
In this video various uses of the U-shaped major connector are explored. In this scenario, the palatal torus is inoperable and extends to the vibrating line. The anterior teeth contact end-to-end. Periodontal prognosis is excellent. Low frenal attachments exist in # 4, 13 areas. The U-shaped major connector is indicated in the presence of large inoperable palatal torus. This design is objectionable because of the possibility of lateral flexure and torque to the abutments. The strap portion would need to be made thicker to resist flexure or wider which could impinge on gingival tissue. Very little if any indirect retention exists. The fulcrum line is noted in red. This design incorporates more lateral bracing and indirect retention. The addition of lingual plating increases the rigidity of the framework, provides better vertical and cross such support, and indirect retention. Ladder retained acrylic may be used as a base material. The acrylic base may be relined, replaced, or repaired as needed to maintain intimate contact with soft tissue. Metal bases are more hygienic but the lack of support from the hard palette cannot compensate for the gradual loss of alveolar ridge height and a base that may be relined is preferred. When employing the vertical minor connector as the reciprocating component of the clasp assembly, any additional reciprocation of the primary abutment such as plating should not inadvertently relocate the fulcrum point by impinging above the height of contour when the partial denture is in function. If the retention is mesial or mid buccal the I-bar may be used. If retention is (on the) the mesial, a cast round or wrought wire may (also) be employed. Anterior-posterior rocking of the partial denture in function would contraindicate use of the mesial component of an embrasure clasp as well as the obvious aesthetic disadvantages and aggressive tooth preparation required for the use of the embrasure clasp. As an alternative, the major connector may be designed as a maxillary lingual plate. This design would normally be used as part of a palatal coverage acrylic base in cases of extreme vertical Ridge resorption and abutments that cannot be splinted. However the presence of the torus prevents palatal coverage. The altered cast may be performed on this framework if an anterior posterior discrepancy exists. Of course, the palatal acrylic border should be tapered and highly polished to lessen irritation to the tongue. The major connector is often textured to provide a more natural feeling surface.