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Biomedical subjects

O L Bezzon

Publications and source records attributed to O L Bezzon.

15 recordsLinked to original sources
PubMed2001

Pilot study of the relationship between the hardness and abrasion resistance of two base metal alloys used for metal-ceramic restorations.

STATEMENT OF PROBLEM: Base metal alloys present high values of strength and hardness, which have been associated with the greater abrasion resistance and polishing of metal-ceramic restorations. However, surface hardness has been shown to be a poor indicator of abrasion resistance. PURPOSE: The study aimed to compare the hardness and abrasion resistance of Ni-Cr alloys and determine whether there is a correlation between these 2 properties. MATERIAL AND METHODS: Two Ni-Cr alloys for metal-ceramic restorations with different hardness values were subjected to the following procedures: (1) initial measurement of Vickers hardness, (2) a series of abrasion cycles, (3) measurement of mass loss after each cycle, and (4) Vickers hardness measurements after each cycle. RESULTS: For each alloy, linear regression revealed a negative correlation between hardness and reduction in mass. The higher hardness of alloy A was associated with higher mass loss during abrasion when compared with alloy B. CONCLUSION: There was no significant correlation between hardness and mass loss for either alloy.

Chromium Alloys↗
PubMed2001

Castability and resistance of ceramometal bonding in Ni-Cr and Ni-Cr-Be alloys.

STATEMENT OF PROBLEM: Because of its pathogenic potential, the importance of the use of beryllium with Ni-Cr alloys must be determined. PURPOSE: This study compared fundamental properties for the clinical use of Ni-Cr alloys, determining the advantage of the addition of beryllium, despite the involved risks. MATERIAL AND METHODS: Two Be-free commercial alloys (Vera Bond II and Wiron 99) and 1 Be-free experimental alloy (E3) with Nb and/or Mo in their formulations and 1 experimental Ni-Cr alloy (E4) with 1.1% Be were submitted to ceramometal bonding resistance, castability, and hardness tests. RESULTS: Analysis of variance showed significant differences (P=.05) between Vera Bond II and Wiron 99 (Be-free) and the E4 alloy for the castability test. Vera Bond II, Wiron 99, and E4 presented higher castability values than E3. There were no statistically significant differences for the ceramometal bonding resistance test. The Kruskal-Wallis test showed significant differences (P=.01) among the alloys with Rockwell 30 T values for the hardness test. CONCLUSION: Within the limitations of this study, the presence of Be in Ni-Cr alloys was not necessary to guarantee the castability and the ceramometal bond resistance of the alloys tested.

Analysis of Variance↗
PubMed2001

Esthetic options for the fabrication of removable partial dentures: a clinical report.

This clinical report describes a procedure for influencing the esthetics of a Kennedy Class III-Modification 1 removable partial denture. The acrylic resin base is eliminated, and the retentive clasp placed on the first premolars is modified. This technique is simple and inexpensive, and in the treatment presented, it resulted in complete patient satisfaction.

Acrylic Resins↗
PubMed2000

Device for recording the path of insertion for removable partial dentures.

Some negative outcomes of oral rehabilitation using removable partial dentures (RPDs) can be prevented when the framework of the RPD is planned with mounted diagnostic casts that have been analyzed in a dental surveyor. Recording the established path of insertion can be difficult when the procedure uses a pin that is cemented in the cast base, and the casts are mounted in an articulator. This article presents a procedure for a pin device to record the path of insertion of RPDs. This device serves the same purpose as the cemented pin but can be easily removed and replaced.

Dental Articulators↗
PubMed2000

A clinical evaluation of materials for interocclusal registration in centric relation.

Four techniques for interocclusal registrations of centric relation based on materials or combinations of materials usually utilized were tested by means of mounting of casts for a patient with partial lower edentulousness, without a free end saddle. To ensure the correct position of centric relation a Lucia jig was utilized. The following conditions for the record of posterior section were tested: registrations with wax, wax plus zinc oxide-eugenol paste, wax plus Duralay acrylic resin, and condensation silicone (putty). The evaluation was made by the measure of vertical distance between reference points in the base of the casts and calculation of variations occurring with each material. The combinations of wax plus zinc oxide-eugenol paste and wax plus Duralay acrylic resin showed the smallest variations in centric relation position.

Acrylic Resins↗
PubMed2000

Tooth wear and loss: symptomatological and rehabilitating treatments.

The authors report a clinical case that presented tooth wear and absence, with painful muscular and articular symptomatology, and also alteration in deglutition, mastication and speech. The clinical procedures used were re-establishment of vertical dimension of occlusion, mandibular centric relations, and occlusal contacts through therapeutic removable partial dentures. The condyle position was analyzed in habitual occlusion and in occlusion with dentures, through transcranial radiographs of the temporomandibular joints. Oral rehabilitation was achieved with dental restoration and removable partial dentures.

Adult↗
PubMed1998

Effect of beryllium on the castability and resistance of ceramometal bonds in nickel-chromium alloys.

STATEMENT OF PROBLEM: Castability and ceramometal bond resistance play an important role in accepting nickel-chromium alloys as a substitute for gold alloys in dentistry. PURPOSE: This study was developed to verify the effect of beryllium on these factors in several compositions of nickel-based alloys by submitting them to castability and ceramometal bonding resistance tests. MATERIAL AND METHODS: Three experimental compositions of Ni-Cr alloys with different amounts of beryllium were used. One beryllium-free alloy was used as the control. RESULTS: Analysis of variance and Tukey's test showed significant differences (alpha = .001) for the castability test results and significant differences (alpha = .05) for ceramometal bond resistance between alloys. CONCLUSIONS: Although the amounts of chromium, manganese, and niobium were maintained, the variations in the amounts of beryllium allowed the estimation that Be-containing alloys presented better castability than Be-free alloys. The 0.9% Be-containing alloy demonstrated higher resistance of the ceramometal bond than the Be-free alloy.

Analysis of Variance↗
PubMed1998

Maintenance of prosthetic treatment in a geriatric patient--case report.

A 76-year old female patient came to the Specialized Clinic for Long-Lasting Dentures of the Dental School of Ribeirão Preto, USP, for prosthetic treatment for the correction of the absence of several teeth. The patient's medical history and examination revealed the presence of psoriasis that had progressed to a rheumatoid arthritis-like condition causing motor deficits such as difficulty in picking up and holding a toothbrush. We proposed two acrylic removable partial dentures, with a chromium-cobalt metal support planned for the lower denture. For the maintenance of oral hygiene we proposed an acrylic resin device coupled to the toothbrush in order to increase the volume of the toothbrush, and consequently facilitate tooth brushing. This device, although simple, has permitted the patient to have a more independent and healthy life style.

Aged↗
PubMed1997

Surveying removable partial dentures: the importance of guiding planes and path of insertion for stability.

STATEMENT OF PROBLEM: Although removable partial dentures are a favored option for the restoration of many situations that involve partial tooth loss, some patients are not satisfied with a removable partial denture, especially when it is not stable during mastication. A dental surveyor can be used to prevent countless problems related to the production of removable partial dentures. Many professionals working with oral rehabilitation fail to take advantage of the many uses of a surveyor in planning and designing chromium alloy and other metal removable partial denture frameworks. PURPOSE: This article uses an academic approach to describe the criteria used to determine the path and removal of a removable partial denture. A fundamental requirement for understanding the correct use of the dental surveyor is to prevent indiscriminate use of a path of insertion perpendicular to the occlusal plane, and extreme inclinations of the cast in the attempt to create undercuts on some teeth.

Chromium Alloys↗
PubMed1997

Immediate partial denture with a cast metal framework. A 6-year evaluation.

The use of dentures immediately after tooth removal is a common practice in dentistry especially when tooth extraction causes aesthetic problems. In the field of complete dentures, the procedure for the construction of immediate dentures permits the preparation of prostheses with the characteristics of standard dentures that can be used for a long period of time, promoting the recovery of function and aesthetic appearance without impairing patient comfort. For removable partial dentures, immediate prostheses are usually provisional for use over a short period of time while the extraction site heals. These dentures are usually made with acrylic resin and wrought wires, and in addition to compressing delicate parts of the support system, often do not provide the comfort and security needed by the patient. Immediate removable partial dentures with a metal framework are seldom used for this procedure, probably because of the difficulty in fitting the framework prior to surgery. The authors present a clinical example in which a modification of framework positioning permitted previous fitting of the framework, eliminating the possibility of lack of fit after tooth extraction, which resulted in clinical success 6 years later.

Dental Casting Technique↗
PubMed1994

An interocclusal record made of a combination of wax and acrylic resin.

The correct mounting of casts on articulators is a fundamental step in obtaining good clinical results and reducing the time spent in the adjustment of oral prostheses. This procedure for retruded contact mounting of casts, based on a tripod of contacts with a combination of wax and acrylic resin, permits great accuracy in a short period of time.

Acrylic Resins↗