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Biomedical subjects

M Zalkind

Publications and source records attributed to M Zalkind.

At least 19 recordsLinked to original sources
PubMed2003

A clinical and radiographic evaluation of fixed partial dentures (FPDs) prepared by dental school students: a retrospective study.

In recent years, there has been an increasing interest in fixed partial dentures (FPD) quality, expected lifetime and possible reasons for failure. This study probed the FPD success rate and the relationship among various factors and their effect on FPD failure. Patients treated by dental students under supervision and installed FPDs were examined clinically and radiographically. A total of 247 FPDs were evaluated after a mean service period of 6.3 years (ranging from 1 to 25 years) after cementation. Caries was found to be the most frequent cause of failure and non-vital abutments decreased survival rates.

Adult↗
PubMed2003

Effect of design of pre-fabricated posts and post heads on the retention of various cements and core materials.

The retention of new Para Post (PP) rounded undercut post head (PP-XT) was compared with the conventional flattened head (PP-P), using amalgam Dentacore and Synergy composite as core materials. The retention of the posts PP (passive serrated), PP-P (passive serrated with venting channels), PP-XP (passive, raised diamond-style pattern) and PP-XT (threaded on the coronal portion, and passive, raised diamond-shaped pattern on the apical portion), cemented with zinc phosphate cement (ZPC) or Duo Cement to extracted teeth, was evaluated. Tensile strength plots were recorded using an Instron instrument, while pulling the post and core in opposite directions. The following conclusions were drawn from this study: (i) The round undercut PP-XT head was more retentive than the PP-P head with both core materials. (ii) Amalgam was more retentive than Synergy with both head designs. (iii) PP-XT was the most retentive post to extracted tooth canals and PP-XP was the least retentive with either ZPC or Duo Cement. Post retention with (iv) ZPC in decreasing order of magnitude: PP-XT > PP-P > PP > PP-XP; and with Duo Cement: PP-XT > PP > PP-P > PP-XP - ZPC exhibited the highest retention of cemented posts.

Bisphenol A-Glycidyl Methacrylate↗
PubMed2003

Resin-bonded fixed partial denture retention: a retrospective 13-year follow-up.

A total of 51 resin-bonded fixed partial dentures (RBFPDs) were inserted under controlled clinical conditions and evaluated over a period of 13 years. Three levels of survival were defined: complete survival (no debonding); functional survival (loss of retention on one occasion with rebonding of the original RBFPD); and multiple survival (loss of retention on several occasions with rebonding of the original RBFPD). The effect of the aetiology, location (anterior/posterior or maxillary/mandibulary) and number of units of the missing tooth on RBFPD survival rates were investigated. The mean survival times and confidence levels were determined for each survival category, using the Kaplan-Meier procedure. The relative risks were calculated by the Cox regression procedure. The overall complete survival level of the study population at the end of the follow-up period was 85 months +/- 13%. Rebonding the RBFPDs once increased the overall functional survival rate to 112 months +/- 10% and multiple rebonding led to a further increase to 131 months +/- 8%. The RBFPD placement under conditions of good periodontal support in which orthodontic treatment was not required, such as trauma among other factors, showed significantly higher survival rates than those placed after periodontal or orthodontic treatment. This indicates that, under both these conditions, RBFPDs may serve as long-term or semi-permanent restorations.

Adolescent↗
PubMed2001

Prosthetic considerations in the restoration of orthodontically treated maxillary lateral incisors to replace missing central incisors: a clinical report.

The treatment of young patients with missing maxillary incisors poses a challenge to prosthodontists and orthodontists. The 2 principal treatment options are (1) the reopening or maintenance of space for future autotransplantation and/or prosthodontic restoration of the missing teeth, or (2) total orthodontic space closure, followed by prosthodontic modification of the lateral incisors to simulate the central incisors. This article discusses only the second option and describes 2 alternative methods for the modification of crown anatomy. These procedures facilitate the orthodontic closure of missing central incisor spaces to ensure satisfactory, esthetic results.

Adolescent↗
PubMed2000

Effect of prefabricated metal post-head design on the retention of various core materials.

Retention of various post heads to core restorative materials is an important factor in the selection of prefabricated post systems and restorative materials for the restoration of endodontically treated teeth. This study examines the retention of a post-core prefabricated system in relation to core material and post-head design. A total of 60 samples were prepared using two different post systems (ParaPost Plus (PP) and ParaPost Unity (PU), with amalgam, composite or glass-ionomer as one of the core materials. The samples were tested using the Instron testing machine. The PP was superior to the PU prefabricated post with respect to the retention of various core materials. Retention values in descending order of magnitude were found to be: composite, amalgam and glass-ionomer (significantly lower). The rhomboid serrated design of PP was superior in retention to the rounded smooth UP system. Composite material proved to be superior in retention, closely followed by amalgam, with glass-ionomer significantly less retentive.

Analysis of Variance↗
PubMed1999

New all-ceramic indirect post-and-core system.

The increasing demand for highly esthetic, biocompatible posts and cores has led to the development of metal-free, post-and-core systems. This article describes and evaluates an indirect method for the fabrication of an all-ceramic post and core.

Aluminum Silicates↗
PubMed1998

Esthetic considerations in restoring endodontically treated teeth with posts and cores.

Posts and cores are often required for the restoration of endodontically treated teeth. Many methods for making post-and-core reconstructions have been described. With the increased use of all-ceramic systems for esthetic tooth restorations, there is a need for esthetic core reconstructions. This article describes several methods for fabricating esthetic posts and cores.

Dental Porcelain↗
PubMed1998

The effect of dental alloys on mouse lymphocyte subpopulations.

The aim of the present study was to determine the effect of nickel-containing alloys on lymphocyte subsets in an experimental setting. Plates of alloys containing nickel (Ceramalloy, Talladium, Cerillium, Rexillium) or gold (Orion) were implanted subcutaneously into mice. The levels of CD4+ and CD8+ T-lymphocyte subpopulations and of Smig+ B lymphocytes were determined at various intervals following implantation, using monoclonal antibodies and flow cytometry. No changes were detected in the proportion of the lymphocyte subsets tested. One month after implantation, the mean fluorescence intensity of CD4, CD8 or Smig, in the peripheral blood lymphocytes (PBL) of the nickel alloy-implanted animals, was significantly higher than that prior to this procedure. Only a mild increase in CD4 and CD8 was noted after implantation of the gold alloy. The observed effects are most likely attributable to the surgical trauma, and do not indicate that nickel-containing dental alloys influence T cell subsets in this murine model.

Animals↗
PubMed1998

Bond strength of photocured composite resin facings: clinical versus laboratory procedures.

The tensile strengths of laboratory versus clinical photocured composite resins have been investigated. Metal surfaces were bonded to photocured composite resin by either retentive beads, Sebond or Silicoating. The bond strengths were measured by an Instron machine and the fracture sites observed. Following repair with the adhesives Dentacolor Opaquer, Fusion and Cover up 2, the Instron measurements were repeated. The metal/facing bond strength was the highest in samples fabricated by the Silicoating technique, the bond strength exceeding the cohesive forces in the composite resin facing. The tensile strengths of metal/facing bonded by Sebond and retentive beads were similar. Fractures that include the facing and partially reveal the metal are the least resistant to tension after repair. Renewal of the Opaque layer and completion of the facing is superior to any of the repair methods used in this paper. The original fracture point is the weakest after repair. All the repair kits tested were inferior to the original restoration materials.

Adhesiveness↗
PubMed1997

Alternative method of conservative esthetic treatment for gingival recession.

The health and appearance of gingival tissue play an essential role in esthetics. The esthetic function of the tissue is enhanced when it frames the restoration. With gingival recession, the effect of natural gingiva is created with pink composites or ceramics on the cervical part of the crown, as described in this clinical report. This goal depends on the absence of adverse effects on the color, shape, and health of the surrounding tissue. The new composites are more color stable and wear resistant, and the latest generation of dental bonding agents allows the bonding of composites to dentin, various metals, and porcelain. The application of soft-tissue colored composite on dentin cementum, enamel, or porcelain is a good solution for correcting gingival recessions.

Acid Etching, Dental↗
PubMed1997

Hypersensitivity to methyl methacrylate: mode of treatment.

This article describes the treatment of a patient who experienced a delayed hypersensitivity reaction associated with acrylic resin. Patch testing revealed an allergy to methyl methacrylate monomer. Patients with a known or suspected allergy of this type should be treated by alternative methods. Dental procedures in which negligible contact of the oral mucosa with methyl methacrylate are presented.

Acrylic Resins↗
PubMed1997

Laminate veneer provisionalisation.

The advantages of provisional laminate veneers are described. Provisional coverage is justified both from the aesthetic and functional viewpoints. Both direct and indirect methods for fabricating provisional laminate veneers are outlined. Among the direct methods for Laminate Veneer fabrication, the use of the preoperative impression, preformed polycarbonate crowns, and vacuform matrix are presented. These methods are quick, fabrication is easy, and the results are highly aesthetic with good patient comfort and satisfaction.

Dental Restoration, Temporary↗
PubMed1996

Histochemical analysis of dental hard tissues following bleaching.

The effect of commonly used bleaching materials on the dental hard tissues was tested in extracted human premolars. In each tooth, the apical two-thirds of the root was removed, and the remaining tooth stump was cut longitudinally into two equal segments. The segments were cleaned, dried, and divided into six experimental groups. Each group was treated with one of the following bleaching materials: 30% hydrogen peroxide (HP), 10% carbamide peroxide (CP), sodium perborate (SP), Nu-Smile (NS), Opalescence (Op), and DentlBright (DB). Treatment consisted of immersing the specimens in the respective test material followed by incubation at 37 degrees C for 7 days. The levels of calcium, phosphorus, sulfur, and potassium were measured in the enamel, dentin, and cementum. In the enamel, a significant reduction in the calcium/phosphorus (Ca/P) ratio was found following treatment with HP. In the dentin, a significant reduction in Ca/P ratio was found following treatment with HP,CP, DB, and Op. In the cementum, a significant reduction in the Ca/P ratio was found following treatment with HP, CP, NS, and Op. Changes in sulfur and potassium levels also occurred, but were usually not statistically significant. Significant reduction in sulfur levels occurred only in the cementum following treatment with CP and SP. Sulfur levels increased significantly following treatment with NS. Significant reduction in potassium levels occurred only in the dentin following treatment with CP. It is concluded that bleaching materials may adversely affect the dental hard tissues and should be used with caution.

Borates↗
PubMed1996

Surface morphology changes in human enamel, dentin and cementum following bleaching: a scanning electron microscopy study.

Extracted human premolars were cut, cleaned and divided into 6 experimental groups. Each group was treated with one of the following bleaching materials: 30% hydrogen peroxide, 10% carbamide peroxide, sodium perborate, Nu-Smile, Opalescence and DentlBright. Morphological changes in tooth surface occurred following treatment with most bleaching agents. Hydrogen peroxide and DentlBright were associated with surface changes in all dental tissues. Hydrogen peroxide, DentlBright, Nu-Smile and Opalescence were mainly associated with surface changes in the cementum, which exhibited more changes than the other tissues.

Borates↗