Occlusal Rest Research Articles

Clinical evaluation of removable partial denture rest seat adaptation

The clinical relationship between the removable partial denture cast occlusal rest and the corresponding rest seat was examined. Under the conditions of the study, it was found that rests of mandibular Class I and II removable partial dentures fit significantly better than those of mandibular Class III and IV prostheses. No significant difference was noted between similar types of maxillary removable partial dentures in this regard. In evaluating the fit of specific portions of the occlusal rest, it was found that the marginal ridge zone was more closely adapted to the rest seat than other zones for all types of removable partial dentures. However, contact, as defined in this analysis, was found to exist on a random basis in all four quadrants of the occlusal rests evaluated. In spite of this fact, one fifth of the occlusal rests did not contact the opposing rest seat at any point. Improved fit with length of service was not substantiated by a cross-sectional analysis. Suggestions were made to assist the clinician in achieving a better fit between the framework and dentition in removable partial dentures.

Endodontically treated teeth as abutments

occlusal rest (Fig. 5, B), and guiding planes (Fig. 5, C). If there are voids or irregularities, they are filled with monomer and powder with a paint brush. 9. Try-in the removable partial denture (Fig. 6) to ensure a proper adaptation of the resin coping (Fig. 7). The die spacer can be removed from the tooth with a cotton pellet soaked in die spacer thinner. Rinse the tooth several times before cementing the temporary restoration. 10. Transfer the resin coping to the working stone die and finish the margins with wax (Fig. 8). If the surface of the resin coping is not smooth, paint it with a thin layer of liquid wax (Hi-Glass liquid wax glaze, George Taub Products and Fusion Co., Inc., Jersey City, N.J.) before investing and casting. There is little need for an opposing cast because the coping has all the details of the previous cast crown or tooth before preparation; but an opposing model can be used to verify occlusal relationships. 11. Cast, polish, and finish the casting. At the try-in stage, the margins and the occlusion are secured. Finally, adaptation of the RPD to the new crown is appraised (Fig. 9). Cement the crown when all necessary adjustments have been made.

Replacement technique for a broken occlusal rest

A simple technique for repairing the RPD with a broken occlusal rest in described.

The efficiency of an indirect retainer

1 wo reports of recent prosthodontic research have dealt specifically with indirect retainers, but only in a general way. I, 2 Several other articles have mentioned indirect retainers as they relate to the design of an entire prosthesis”-“’ or their relative effect on abutment tooth movement.“-‘* Most reports4-1f1 that mention indirect retainers cite one or more of the following general principles: ( 1) They are needed in extension-base removable partial dentures; (2) they should be located as far from the primary fulcrum line as possible; (3) they should be placed on a positive rest seat, especially if on an anterior tooth; (4) they help in resisting rotational movement of the denture base away from the ridge and lateral movement of the restoration; and (5) they can take the form of an auxiliary occlusal rest, cingulum rest, embrasure hook, secondary Kennedy bar, or linguoplate. Few, if any, of the reported functions of indirect retainers have been studied, nor has their efficiency-particularly as it relates to resting on anterior teeth. The purpose of this study was twofold : ( 1) t o investigate the efficiency of indirect retainer design as it relates to anterior teeth and (2) to determine if the type of direct retainer design has any effect on the efficiency of indirect retainers.

Influence of occlusal rest position and clasp design on movement of abutment teeth

1. When treatment with a removable partial denture is necessary, the transition region from tooth to mucosa support must receive most careful consideration. 2. An occlusal rest placed on the mesial or anterior part of the most distal abutment tooth provides mucosa or soft tissue support more perpendicular to the residual alveolar ridge than does one on the distal side of that tooth. 3. The gingival mucosa adjacent to the most posterior tooth is less likely to be pinched when the occlusal rest is placed on the mesial side of the tooth. 4. The occlusal rest providing a mesial rotation point will tend to tip the abutment tooth anteriorly where it will be reinforced and assisted by other teeth. 5. All extracoronal retainers alter the natural tooth contour and interfere with proper stimulation of the gingivae and natural cleaning action. The infrabulge I bar design alters natural tooth contour the least and allows for more natural gingival stimulation than any other type of extracoronal retainer. The area of contact of the clasp with the tooth is minimal. 6. The I bar retentive clasp, when placed at the point of greatest circumference of the tooth and used in conjunction with a mesio-occlusal rest or anterior rotation point, will exert no adverse or torquing force on the abutment tooth. 7. The region of the junction between the tooth and the edentulous area exhibits pathosis most frequently. The tooth contact should be made with a thin metal plate which extends onto the soft tissue for at least 1 mm. This will increase cleanliness and prevent mutilation of the denture base which results in a space at the tooth-mucosa junction. 8. The metal-tooth contact at the distal gingival region must be physiologically adjusted in the patient's mouth to prevent tooth and tissue impingement.

The biomechanics of removable partial dentures and its relationship to fixed prosthesis

Clasps will always be used for attachments for removable partial dentures. However, they have many disadvantages and possible destructive effects, some of which follow: 1. Caries may develop around and under clasp arms. This develops particularly when the patient fails to keep the appliance clean. 2. Strain is placed on the abutment tooth. A clasp as an attachment imparts a heavier load to the abutment tooth than an internal attachment. The forces applied by the clasp are not as nearly vertical as they are when an internal attachment is used. 3. The occlusal rest is likely to be weak. 4. Clasps have poor esthetics and leave much to be desired from an esthetic point of view. 5. Internal attachments tend to save abutment teeth for a longer period of time than do external attachments.