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Biomedical subjects

S M Morgano

Publications and source records attributed to S M Morgano.

At least 19 recordsLinked to original sources
PubMed1998

The effect of temperature changes on the dimensional stability of polyvinyl siloxane and polyether impression materials.

STATEMENT OF PROBLEM: Dental impressions are commonly mailed to remote dental laboratories and can be subjected to extreme temperature changes; however, the effects of these temperature changes on the accuracy of elastomeric impression materials are unknown. PURPOSE: This study evaluated the dimensional changes of polyether and polyvinyl siloxane impression materials as a function of storage temperature. MATERIAL AND METHODS: A total of 144 impressions were made of a stainless steel die similar to ADA Specification No. 19. Half of the impressions were made in perforated custom trays and the other half in solid trays. Measurements of the vertical and horizontal lines on the impressions were made at 10 minutes, 1 hour, 24 hours, and 26 hours, and storage temperatures ranged from 4 degrees C to 40 degrees C. RESULTS: Changes in storage temperature had a statistically significant effect on the dimensional stability of the horizontal and vertical lines. However, overall dimensional changes were extremely small. CONCLUSIONS: Storing both impression materials at 4 degrees C for 24 hours and then allowing the impressions to reach room temperature resulted in a slightly expanded impression that partially compensated for the contraction that occurred from polymerization shrinkage. Similar results occurred for polyether material only, when stored at 40 degrees C.

Analysis of Variance↗
PubMed1998

Four uses of a disposable implant mount.

The high cost of precision-fitting, machine-milled implant components is a major concern, and the dentist with a busy implant practice must stock numerous components at considerable expense. In this article, the use of a disposable implant mount is described as an adjunct for a positional index during stage-I surgery, immediate provisional restoration at stage-II surgery, verification jig, and implant-supported record base. By reusing the precision-fitting implant mount that is supplied free of charge by the manufacturer, the dentist can reduce the overhead costs required to provide implant prosthodontic treatment.

Dental Implantation↗
PubMed1998

Use of aluminum strips to fabricate verification jig for an implant-supported fixed partial denture.

Verification of the accuracy of the master cast for an implant-supported fixed partial denture will reduce the chair time and laboratory costs of implant prosthodontic treatment. A wire is usually luted in the mouth to machined components that have been secured to the implants, and the luted assembly is then transferred to the cast to evaluate the positional accuracy of the implant analogs. Unless this wire is dead soft, inaccuracies as a result of elastic memory of the wire can occur. Also, if the wire is not completely rigid, it can be distorted during handling. This article describes a more reliable verification jig for an implant-supported fixed partial denture that can be fabricated with 1.5 mm thick aluminum strips that are luted to the implant components. The use of two aluminum strips creates a metal framework that is rigid and not easily distorted. Also the aluminum pieces do not have elastic memory because they were cut and not bent to shape.

Aluminum↗
PubMed1997

Vacuum-formed matrix as a guide for the fabrication of multiple direct patterns for cast posts and cores.

Fabrication of multiple posts and cores for severely damaged pulpless teeth is arduous because few landmarks remain. Esthetic requirements, occlusal relations, and long axes of the planned final restorations influence the core design. This article describes a method for directly verifying fabricated post-and-core patterns by combining the procedures for making a thermoformed shell for a preparation template and creating a plastic template for multiple core pattern fabrication.

Humans↗
PubMed1996

Restoration of pulpless teeth: application of traditional principles in present and future contexts.

Posts were recommended more than 100 years ago to retain artificial crowns. Recent studies suggest that posts can weaken teeth; therefore restorative procedures that help preserve pulpal vitality and eliminate the need for posts are desirable. If endodontic therapy is unavoidable, conservation of remaining tooth structure is most important. When a post is required to retain a core for an artificial crown, a custom cast post is the most effective means of conserving tooth structure. The length of the post should not be compromised, although 4 to 5 mm of apical gutta-percha must be maintained. The restorative prognosis is improved if the width of the post does not exceed one half the width of the root, and the cemented artificial crown should extend apical to the core to provide a 1.5 to 2 mm ferrule. Complex procedures have allowed the dentist to restore extensively damaged teeth. However, extraction and replacement with implant-supported prosthodontics may be more prudent with severely compromised teeth.

Dental Abutments↗
PubMed1996

Complete edentulism and denture use for elders in New England.

The purpose of this study was to collect information about the oral health of a representative group of elders in the New England states. This study provides the most current descriptive analysis of completely edentulous noninstitutionalized elders to date. In-home examinations and interviews were conducted for a representative sample of elders over 70 years of age. The oral examinations and interviews were conducted by calibrated dentists and trained interviewers, respectively. Of 1156 study participants, 424 (36.7%) were edentulous. Edentulous rates were similar for men and women and were negatively related to levels of education and income. Of the completely edentulous individuals, 89.9% had maxillary and mandibular complete dentures. Most of these dentures (83.2%) were worn during the day. More than one third of the respondents reported wearing one or both of their dentures while sleeping at night. For 77 of the completely edentulous individuals, examination revealed denture irritations, most of which were on the hard palate.

Aged↗
PubMed1996

Effects of chemical disinfectant solutions on the stability and accuracy of the dental impression complex.

Currently available impression materials were not designed for disinfection or sterilization, and it is conceivable that disinfectants may adversely affect impressions. This study evaluated the accuracy and dimensional stability of polyether (Permadyne/Impregum) and polyvinyl siloxane (Express) impression materials retained by their adhesives in two different acrylic resin tray designs (perforated and nonperforated) when the materials were immersed for either 30 or 60 minutes in three high-level disinfectants. Distilled water and no solution served as controls. A stainless steel test analog similar to ADA specification No. 19 was used. A total of 400 impressions were made with all combinations of impression materials, tray designs, disinfectant, and soaking times. Samples were evaluated microscopically before and after immersion and 48 hours after soaking. Results indicated that these two impression materials were dimensionally stable. Because the results emphasized the stability and accuracy of the impression complex under various conditions, dentists can perform disinfection procedures similar to the protocol of this study without concern for clinically significant distortion of the impression.

Analysis of Variance↗
PubMed1995

Effects of ultrasonic scaling and periodontal curettage on surface roughness of porcelain.

Changes in the surfaces of glazed porcelain were evaluated with the use of a profilometer and a scanning electron microscope after ultrasonic scaling and periodontal curettage. Thirty samples of glazed porcelain-fused-to-metal were divided into two experimental zones, and the two scaling treatments were performed on each sample. Measurements of surface roughness of porcelain were made before and after instrumentation for both periodontal prophylaxis procedures. The statistical analysis of the differences in surface changes as evaluated on the profilometer indicated that the roughness alterations from both procedures were not statistically significant; however, the qualitative or subjective evaluation of scanning electron micrographs and profile tracings revealed differences between glazed and instrumented porcelain surfaces.

Dental Alloys↗
PubMed1995

A procedure for making fixed prosthodontic impressions with the use of preformed crown shells.

Void-free impressions of tooth preparations for fixed prosthodontics are essential for accurately fitting restorations; however, commonly used impression methods are arduous and time-consuming. A procedure has been developed in which an impression is made in a preformed temporary crown shell for each tooth preparation and then a final over impression is made. The result is an atraumatic and uncomplicated complete-arch impression that incorporates an accurate impression of each prepared tooth.

Crowns↗
PubMed1995

Ability of various impression materials to produce duplicate dies from successive impressions.

This in vitro study evaluated the ability of five different impression techniques to make duplicate dies of two different types of tooth preparation. One mandibular second premolar Ivorine tooth was prepared for a complete crown and one for an onlay. A master impression was made of each tooth preparation with the use of five impression techniques for a total of 10 master impressions, and a master die was made from each of these impressions. Castings were made on these master dies, and the fit of each casting was verified on the respective Ivorine tooth. Marginal openings of the castings on the master dies were recorded under magnification at four predetermined points. Five successive impressions, with the use of each impression material, were then made of each tooth preparation for a total of 50 test impressions, and 50 test dies were made from these impressions. The fit of the respective casting was evaluated under magnification for each test die at the four predetermined points, and marginal openings were recorded. Differences between the marginal discrepancies of the casting on the master die and on the test die were tabulated and the results were statistically analyzed. Results indicated that none of the impression materials was capable of producing exact replicas. Polysulfide rubber performed significantly better than two materials for the production of duplicate dies with the complete crown preparation; and polyvinyl siloxane used with a putty-light body, single-stage technique produced mean marginal discrepancies that were significantly greater than the other four techniques when used for the onlay preparation.(ABSTRACT TRUNCATED AT 250 WORDS)

Bicuspid↗
PubMed1995

Repair of posterior base of a maxillary complete denture by use of a cast of stone and resilient material.

A method to repair a fractured complete denture and simultaneously augment deficient borders or correct an inadequate posterior palatal seal is described. Corrections were made intraorally with modeling compound and an elastomeric impression material. A resilient impression material was used to block out the undercuts in the denture, and repair was accomplished with visible light-cured resin or an autopolymerizing repair resin. This technique simplifies the laboratory procedures and thereby permits the return of the denture to the patient at the same visit.

Acrylic Resins↗
PubMed1994

Technique to restore unfavorably inclined implants.

Unfavorable inclination of implants is a common problem that may compromise esthetics, phonetics, and function of the implant-supported fixed prosthesis. Several methods have been reported to compensate for malaligned implants; however, most techniques are complicated and expensive. A technique that combines a custom abutment from a hexed UCLA-type plastic burn-out pattern and a manually threaded setscrew hole is a relatively inexpensive and uncomplicated approach to eliminate problems caused by unfavorable implant inclination. This article describes the procedures for fabrication of an implant-supported fixed prosthesis with the use of this technique.

Dental Abutments↗
PubMed1994

A diagnostic stent for endosseous implants to improve conventional tomographic radiographs.

Conventional tomographic radiographs can often provide sufficient information for presurgical evaluation for implant placement with significantly less radiation exposure than computer-assisted tomographic (CT) radiographs. A technique to fabricate a diagnostic stent with a removable indicator for the partially edentulous patient is described. This stent with an indicator guides the radiologist in making conventional tomographic images and can also be used as a template for locating the surgical sites.

Dental Implantation, Endosseous↗