Carl A. Hansen

Dental implications of nickel hypersensitivity

T he rising cost of gold and precious metals has been instrumental in the development of nonprecious alloys in dentistry, including many nonprecious alloys that contain nickel. In recent years, nickel hypersensitivity in humans has been of growing concern among dentists. Contact with nickel by susceptible individuals may produce a spectrum of hypersensitive reactions. Dermatitis and urticaria, the primary manifestations of nickel hypersensitivity, may be found in the area of contact as well as distant from the nickel source.‘s2 Urticaria and dermatitis of the hands, neck, and eyelids are commonly reported hypersensitive reactions to nickel.’ Nickel is a known carcinogen and nickel ions are released from nickel-containing alloys in the oral environment.3a4 It is not known, however, whether the release of nickel ions from dental alloys is high enough to be clinically significant. If so, as a result of the potential alteration in endocrine functions, changes in vital functions such as blood pressure, pulse, and temperature might be expected. Nickel-containing alloys have been linked to a decrease in the number of T-lymphocytes in humans.4 Normal immune function depends on a balance of T4 helper lymphocytes that label foreign cells and microorganisms and T8 suppressor lymphocytes that prevent white blood cells from affecting normal cells.4B 5-8 Indeed, metal allergies from dental alloys have been implicated as a possible cause of the oral lesions of lichen planus.” Nickel contact dermatitis is commonly observed, with some references claiming as high as a 28% positivity in nickel sulfate patch tests among the general population.” The incidence of nickel allergy is higher in women (31.9%), presumably because of sensitization from nickel-containing jewelry. lo With increased use of nickel in nonprecious dental alloys, it would be logical to expect

An esthetic removable partial denture retainer for the maxillary canine

The use of a distofacial ridge on a maxillary canine abutment for a distal-extension base of a removable partial denture is described. The distofacial ridge will permit the placement of a less conspicuous I-bar arm on the distofacial surface of the tooth. The ridge provides bracing against distal movement during function and thus prevents the subsequent loss of retention for the prosthesis. It also permits a more precise path of insertion and withdrawal for the prosthesis. Three methods of establishing a distofacial ridge on a canine abutment are described.

Diagnostically restoring a reduced occlusal vertical dimension without permanently altering the existing dentures

The technique described provides the dentist with a means of diagnostically restoring the vertical dimension of occlusion for an edentulous patient, without permanently altering the dentures. This procedure is accomplished with a removable mandibular splint, which snaps over the mandibular denture. The procedure involves little clinical treatment time. The maxillary denture may also be temporarily overlayed in a similar manner, but the procedure is generally not as esthetically acceptable. Since the mandibular alveolar bone resorbs much faster than that of the maxillae in most edentulous patients, the mandibular denture usually is responsible for most of the loss of occlusal vertical dimension. The mandibular denture is therefore most frequently indicated for alteration to restore lost occlusal vertical dimension. Medicolegal implications, as well as practical considerations, suggest that the patients present dentures should not be permanently altered before new dentures are found to be satisfactory.

Clinical comparison of two mandibular major connector designs: The sublingual bar and the lingual plate

Two mandibular removable partial dentures, one with a sublingual bar and one with a lingual plate as the major connector, were constructed for 10 patients. Both were made using the same impression and were identical except for the design of the major connector. The two major connector designs were evaluated by the patients at the conclusion of the study. Eight of the 10 patients preferred the lingual plate and nine of the 10 found both designs satisfactory. One patient indicated a strong preference for the sublingual bar over the lingual plate and another found both designs equally acceptable. We have concluded from the final data that the sublingual bar compares favorably with the lingual plate in patient acceptance and should be considered as a viable design alternative when a lingual plate is not indicated.

Achieving a passive fit for a screw-retained implant-supported maxillary complete arch ceramometal prosthesis: clinical report.

A technique is described for the fabrication of a full arch maxillary passive-fitting, screw-retained, rigid ceramometal prosthesis. The two posterior segments containing Screw-Bloc attachments are cast initially. The waxed anterior segment with its attachments is then aligned to the cast posterior segments and cast. Porcelain is fired to the individual segments in an attempt to reduce deformation, which occurs when large ceramometal restorations are constructed. When the prosthesis is completely fabricated, the segments are assembled on the master cast and the attachments on the posterior segments are tapped to receive the screws, which rigidly attach them to the anterior segment. The Screw-Bloc attachment has an irregular configuration that resists rotation of the individual segments. The segments are united once the passively aligned screws are tightened. A clinical report is presented. (Implant Dent 1994; 3:31–34)

The segmented framework removable partial denture

The segmented framework removable partial denture is made of two cast metal individual segments joined with a resin major connector. The small individual framework segments can be made to fit well and the design permits ready correction of the tissue surface of the major connector through relining or an altered cast procedure. The dentist is offered a valuable alternative treatment approach in selected patients.

Phonetic considerations of chromium alloy palates for complete dentures

Two useful approaches for the construction of dentures with a chromium alloy palate have been described. The phonetic considerations were recognized, and allowances were made for their vital role when determining the palatal contours of both the metal and plastic portions of the denture base.

A procedure for predictable cast separation

Inadvertent cast fracture can be an aggravating experience. The fracture most often occurs during separation of the cast from its mounting. A thin base on the cast or an inherent potential for cast fracture after an altered-cast procedure are examples. A procedure is described for preventing damage to casts when they are separated from their mountings. This procedure is quickly accomplished and permits accurate remounting when indicated.

Metal minibases in removable prosthodontics

A description of the designs and indications for minibases in removable prosthodontics has been presented. Minibases can solve complicated space problems when surgery is contraindicated by providing a strong, thin, abrasive-resistant denture base. The result of their correct use is a prosthesis that fits well, is extended correctly, functions without opposing interferences at the correct vertical dimension of occlusion, and resists the functional stresses placed on it during service.