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Biomedical subjects

Z Ben-Ur

Publications and source records attributed to Z Ben-Ur.

At least 19 recordsLinked to original sources
PubMed2000

The mandibular first premolar as an abutment for distal-extension removable partial dentures: a modified clasp assembly design.

Sound mandibular first premolars can be used as sole abutments for bilateral distal-extension removable partial dentures, if the denture is designed to minimise the torque applied to the abutment teeth. A simplified modification of the conventional torque-releasing clasp-assembly designs is suggested for these teeth. This modification entails a mesial rest on each abutment tooth connected to the distal proximal plate via a lingual bracing arm. A circumferential clasp arm is optional for buccal retention of the removable partial denture. As with conventional designs, the metal framework is designed to permit some rotational tissueward movement of the distal extension bases, yet not compromise the retention and stability of the prosthesis.

Bicuspid↗
PubMed1999

Stiffness of different designs and cross-sections of maxillary and mandibular major connectors of removable partial dentures.

STATEMENT OF PROBLEM: Major connectors of removable partial dentures must distribute forces bilaterally without damaging the supporting tissues. PURPOSE: This study investigated which design and cross-sectional shape of major connectors most favorably influence rigidity and flexibility. METHODS AND MATERIAL: Five designs for maxillary removable partial denture major connectors and 5 lingual bar major connectors of different cross-sectional forms were cast in chrome cobalt alloy on a master cast. Points M and P, which represented the position of the first premolar and second molar teeth, were positioned 20 mm apart on the casting. Vertical and horizontal forces were applied to each point while the opposite side was gripped in an Instron testing machine. A force-deflection curve was obtained for each loading point. Mean stiffness values were obtained for loading in compression and torsion. RESULTS: Values for torsional loading simulating vertical forces were lower when compared with values obtained for compression loading that simulated horizontal occlusal forces. Differences in stiffness were greater in mandibular major connectors loaded at M and P. The half pear-shaped cross section was the stiffest. CONCLUSIONS: In the maxillary arch, the most rigid major connector was the anteroposterior palatal bar combination placed on different horizontal and vertical planes. The most flexible was the U-shaped design. In the mandibular arch, the most important factor in achieving rigidity was the cross-sectional shape of the major connector. The half pear-shaped cross section proved to be the most rigid.

Bicuspid↗
PubMed1999

Further aspects of design for distal extension removable partial dentures based on the Kennedy classification.

A supplement to the Kennedy classification of partially edentulous arches for restoration with removable partial dentures has been suggested. Factors affecting denture design relating to the position of the abutment teeth, the symmetry of the edentulous distal extensions, the arch form and the cross-sectional shape of the residual ridges have been discussed and classified. An understanding of the movement of the denture bases in relation to the influence of these factors makes for a rational approach to removable partial denture design and the treatment of complications observed clinically in removable partial denture wearers.

Alveolar Process↗
PubMed1996

Prosthodontic treatment for the Applegate-Kennedy class V partially edentulous patient.

Concomitant loss of a canine and adjacent teeth usually occurs in the maxilla as a result of trauma in youngsters with well-preserved dentition or as an outcome of surgical excision of a localized pathosis in that area. It is postulated that in Applegate-Kennedy class V partially edentulous situations, the remaining anterior teeth in the maxilla should not be used as abutments for removable partial dentures. The stability of the prosthesis is maintained by counterresisting the occlusal forces exerted on the restored arch-curve by use of a posteriorly directed path of placement for the prosthesis.

Cuspid↗
PubMed1996

Anterior implant-supported overdentures.

Retention of complete mandibular dentures can be successfully achieved by means of an implant-retained or natural tooth-retained bar and clip system in the anterior segment of the mandible. The same design principles hold true for both methods of anchoring the retentive bar. These retentive elements must be constructed to allow some freedom of movement around a fulcrum line designed to be perpendicular to the sagittal plane.

Dental Prosthesis, Implant-Supported↗
PubMed1995

Removable partial denture with a lateral rotational path of insertion.

A removable partial denture with a lateral path of insertion is useful when unsightly facial clasps are objectional to the patient. Rounded rest seat preparations allow extensions of the minor connector to rotate laterally into embrasure undercuts, providing retention. Guiding planes on the contralateral side ensure a different path of withdrawal from the retentive elements. A Kennedy Class IV arch with a long edentulous span is used to illustrate the denture design.

Dental Clasps↗
PubMed1991

Factors affecting displacement of free-end saddle removable partial dentures.

Tissueward movement of the free-end saddle of a removable partial denture during function takes place around the most distal fulcrum created by the most mesial rests. Displacement because of sticky foods takes place around the fulcrum created by the most distal rests. These and other factors affecting displacement of the free-end saddle removable partial dentures are discussed, and designs intended to increase retention are presented. The forces applied to the most anterior and posterior axes of rotation can be calculated mathematically to reveal the hazards of a too-short lever arm in combination with a strong retentive clasp system.

Dental Stress Analysis↗
PubMed1990

RLS--the lingually retained clasp assembly for distal extension removable partial dentures.

The design of clasp for a distal extension removable partial denture that helps preserve both the abutment teeth and the tissues of the edentulous ridge is described. The clasp assembly takes advantage of surveyed lingual undercuts to provide support, retention, and stability. It consists of a mesio-occlusal rest, a distolingual L-bar direct retainer that is located on the abutment tooth adjacent to the residual ridge, and a distobuccal stabilizer (RLS).

Denture Design↗
PubMed1989

Rigidity of major connectors when subjected to bending and torsion forces.

Rigidity tests were performed on maxillary major connectors of different designs and mandibular major connectors of the lingual bar-type with different cross-sectional shapes and thicknesses. Each major connector was clamped on one side while the other side was subjected to bending, torsion, and bending under torsion forces. Deformation was measured with a micrometer microscope. The most rigid maxillary major connector was the design incorporating the anterior-posterior palatal bar. The most flexible was the U-shaped palatal bar. The full pear-shaped lingual bar (4 x 4 mm) was the most rigid of the major connectors. Among the more conventional lingual bars, the semielliptical bar (3.75 X 1.75 mm) was the most rigid, and the narrow semielliptical bar (4 x 1.5 mm) was the most flexible.

Chromium Alloys↗
PubMed1989

An analysis of rotational movement of asymmetrical distal-extension removable partial dentures.

An axis of rotation is created through the most distally placed occlusal rests when a distal-extension removable partial denture is loaded. If the residual ridges are of unequal lengths, this axis of rotation may not be perpendicular to the residual ridges. The resultant movement of asymmetric denture bases and their effect on the tissues are discussed. Movement of I-bar retainers located on the mesiobuccal aspect of asymmetrical abutment teeth may torque the abutment teeth as the denture base moves tissueward. Use of L-shaped direct retainers on the distobuccal surveyed undercut will create a more favorable class II lever effect on the abutment tooth.

Dental Abutments↗
PubMed1988

A modified direct retainer design for distal-extension removable partial dentures.

The rationale for designing a direct retainer for a distal-extension removable partial denture is described. The advantages of an L-bar clasp arm over the I-bar clasp arm are discussed. The retentive surface of an abutment tooth is divided into three zones according to the clasp tip movement and the importance of placing the retentive tip in the zone of vertical movement is emphasized.

Dental Abutments↗
PubMed1987

Incidence of impression material found in the gingival sulcus after impression procedure for fixed partial dentures.

After impression-making procedures, remnants of Xantopren impression material were found in the gingival crevices in eight of 125 patients. In three of the eight patients, remnants were only discovered subsequent to a systematic exploration with a fine curette. In all eight of the patients in which material was found in the crevice, the location corresponded with defects in the impression itself. Although eight of 125 is not a statistically significant number, it would be nonetheless prudent to consider a routine curettage of abutment sulci after impression-making. This procedure is even more strongly recommended should a defect be detected in the crevicular region of the impression. Impressions should remain in the mouth until full setting and maximum tear strength is reached. Strict adherence to the manufacturers' instructions is necessary.

Dental Abutments↗