Quintessence International, 03/1996

To assess patients' perceptions of different types of fixed anterior restorations, their responses to (1) metal-ceramic versus all-ceramic restorations; (2) National Health Service versus private-contract metal-ceramic restorations; and (3) normal versus overbuilt metal-ceramic restorations were compared. More people thought the all-ceramic crowns were more natural and preferred those restorations. More people thought the metal-ceramic fixed partial dentures were more natural, and those wre also preferred. For both crowns and fixed partial dentures, respondents thought the private work was more natural looking, but the National Health Service work was preferred for the crowns. Respondents thought the crowns and fixed prostheses with normal margins were of a higher technical standard, and those restorations were preferred. The shade and color of the restorations were the most important factors in the patients' assessments.

A survey of the literature indicates that calcium channel-blocking medications are used for an ever-increasing number of medical problems. Their use may result in gingival overgrowth that can be of concern to the patient and dentist. Four cases are presented that illustrate several relevant points: (1) histologic examination may reveal factors overlooked in the medical history; (2) the condition exists in a variety of clinical manifestations; (3) the level of plaque control maintained by the patient is important to the management of the condition; and (4) responses vary to different approaches to treatment, including changes in medication, as well as nonsurgical and surgical therapies.

This preliminary report is based on a survey of the reasons for inserting 790 glass-ionomer cement, 2,609 resin composite, and 898 amalgam restorations in adults in general practice. Glass-ionomer materials were used about equally for the treatment of primary caries and for replacement of failed restorations, unlike resin composite and amalgam, which were most often used to replace failed restorations. Almost half of the 412 replaced glass-ionomer cement restorations were removed because of the clinical diagnosis of secondary (recurrent) caries, which was by far the most common reason for replacement of all three materials.

The performance of a low-cost teleradiology system was studied. The time needed for radiographic transmission between computers and the image integrity following transmission were measured. The image resolution was analyzed with a line-pair test chart. Images were transmitted through computers that had a video-processing board and a modem at both the transmission and receiving sites. Intraoral radiographs were captured with a black and white charge-coupled device camera. The time required for image transmission was less than 1 minute (46 to 56 seconds), an effective transmission speed of 1.73 kbyte/s (13.9 kbit/s). No changes were observed in pixel value distributions; hence, there was no loss of image detail. The maximal resolution of the system was 4 line-pairs/mm. The performance of the teleradiology system demonstrated its potential as an effective, low-cost telenetwork for dentistry

Finding an impression technique that provides a quick and accurate dental impression can be an elusive goal. The combination of a rigid, fast-setting poly(vinyl siloxane) bite registration paste and a disposable closed-mouth impression tray fulfills this goal. The comfort of the pateint is enhanced because a minimal amount of the impression material, which is tasteless, is necessary. The technique enables the dentist to record habitual centric occlusion, the prepared tooth or teeth, and the opposing arch accurately and simultaneously.

One hundred fifty-nine noncarious cervical lesions were restored with glass-ionomer cement, resin composite used with a dentinal bonding agent, or the laminate (sandwich) restoration, which combines both these materials. These restorations were evaluated at baseline, 1 year, and 3 years for color match, cavosurface marginal discoloration, anatomic form, marginal adaptation, and retention. There was a general deterioration of the restorations with time. Lesions restored with resin composite and a dentinal bonding agent exhibited the highest percentage of lost restorations.

A conservative method of replacing missing teeth is described. The fixed partial denture incorporates a resin-bonded retainer for the intact tooth and a telescopic coping for the carious or fractured tooth. A permanently cemented coping beneath a provisionally cemented superstructure provides the opportunity to recement the prosthesis if the acid-etched retainer is debonded. The advantages of this technique include conservation of enamel on the intact abutment and protection from leakage caused by dissolution of temporary cement on the abutment with a telescopic coping.

The aim of this study was to investigate the distortion of metal-ceramic prostheses that occurs during metal-conditioning firing and to examine whether the distortion might be controlled by embedding the castings in an investment bulk and applying a prior heat treatment. The distortion of palladium-copper and nickel-chromium frameworks was evaluated by means of inner fit and horizontal linear measurements of the framework length. There was no statistically significant difference between palladium-copper and nickel-chromium frame-works in the changes in inner fit. In addition, there was no statistically significant difference between the invested test group and the control group in changes in fit. However, the mean deformation in framework length recorded for invested palladium-copper frameworks (-20.20 um) was significantly smaller than that recorded for control palladium-copper frameworks (52.20 um).

The objective of the study was to evaluate the physical properties of four resin-modified glass-ionomer cements (Fuji II LC, Ionosit Fil, Vitremer, Photac-Fil) and two polyacid-modified resin composite materials (Dyract and Variglass VLC). They were compared with a hybrid resin composite (blend-a-lux) and a chemically cured glass-ionomer cement (ChemFil Superior). The compressive strength, flexural strength, modulus of elasticity, and surface micro-hardness of the resin-modified glass-ionomer materials and the polyacid-modified resin-composite materials were inferior to those of the hybrid resin composite and similar to those of the conventional glass-ionomer cement. The hybrid resin composite exhibited the lowest resistance to wear caused by brushing. Some of the materials showed a marked decrease in hardness at depths exceedign 2.0 mm. Generally, the strength properties of the tested resin-modified glass-ionomer materials and the polyacid-modified resin composite materials were inferior to those of the hybrid resin composite.

The in vivo solubility of glass-ionomer, zinc polycarboxylate, and zinc phosphate luting cements was compared. The specimens were inserted in the lingual flanges of the mandibular dentuers of 10 edentulous patients. After 8 months, the cement specimens were removed and the amount of solubility was measured with direct techniques. Scanning electron microscopy was used to evaluate surface topography after disintegration. The elements present in each cement were determined with energy-dispersive spectroscopy. The zinc phosphate and zinc polycarboxylate cements demonstrated approximately equal solubility. Glass-ionomer cement exhibited significantly less solubility than did either zinc phosphate or poly-carboxylate cement.