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Biomedical subjects

S Carossa

Publications and source records attributed to S Carossa.

At least 37 records · Page 2Linked to original sources
PubMed1990

The unreliability of facial measurements in the determination of the vertical dimension of occlusion in edentulous patients.

The aim of this research was to test the reliability of skin markers in the determination of the V.D.O. in edentulous patients during prosthetic rehabilitation. Two resin baseplates were constructed: on the upper one a modified pin of the Central Bearing Point registration device was fixed with impression compound. The height of the pin could be altered by rotating the pin directly in the patient's mouth with a probe. Two lead spheres were inserted on the resin base-plate as bone markers, and two others were fixed to the skin as markers, one above (end of nose) and one below (point of chin) the oral commissure. Five lateral cephalometric radiographs were exposed for each patient, raising the V.D.O. by 1.2 mm on each occasion. Statistical analysis of measurements made on the resulting radiographs showed a very strong correlation between bone markers and pin position, whereas great variation and considerable differences were found between skin markers and bone as well as measurements.

Adult↗
PubMed1990

[Direct rebasing of temporary crowns in the fixed denture. An experimental assessment of the increase in heat at the pulp cavity level].

Self-curing resins are generally used to directly temporary prostheses on the crown abutments. This technique enables the operator to obtain a better marginal adaptation of the temporary prosthesis. The risk of such a procedure is the inflammation of the pulp due to the exothermic polymerization reaction of self-curing resins. The authors suggest experimentally evaluating the rate of thermic increase within the pulp cavity of an extracted tooth while directly relining a temporary crown.

Composite Resins↗
PubMed1990

[An evaluation of the signs and symptoms in patients with craniomandibular disorders correlated with the radiological pictures obtained by OLTP].

The study evaluated the frequency of noise, pain and alterations of mandibular movements in a group of 88 patients. Condylar position was also studied using OLTP X-ray images, and the presence of arthrotic lesions using multitomography. The condylar position was related to the presence of organic lesions at an articular level, and a higher frequency of the latter was found in anterior condylar displacements; the presence of condyles centered in the glenoid cavity on OLTP examination does not exclude the possibility of arthrotic lesions. Another important finding was the observation of a greater frequency of contralateral organic pathologies in posterior condylar displacements.

Adolescent↗
PubMed1990

[Extension bridges. A bibliographic evaluation and the clinical indications].

Extension bridges are a valid alternative to partial and implanted prostheses for the rehabilitation of small intercalary or distal lacunae. Following a critical review of published reports on the subject and the assessment of longitudinal studies, the authors examine the clinical parameters and technical procedures used to implement these prosthetic reconstructions.

Dental Abutments↗
PubMed1990

[A radiographic assessment of condylar position after therapy with the Michigan plate].

The paper analyses condylar movement in the sagittal plane following four months of therapy using a Michigan-type plate in a group of 19 patients with craniomandibular disorders. An OLTP radiographic examination was used; X-rays carried out before and after therapy were compared using a special image subtraction technique. From the analysis of results it emerged that 63.12% of patients showed a mono- or bilateral condylar movement which was visible by X-ray.

Adult↗
PubMed1989

A radiologic method for determining the thickness of the hard crown tissues.

This study describes a radiologic method that provides a reliable evaluation of the thickness of the hard crown tissues of the tooth scheduled for prosthetic and conservative preparation. The first stage consisted of calculating the discrepancy between the actual dimensions of the specimen under examination and the dimensions of the same specimen as measured and radiographed. Some coefficients of distortion were calculated for the distance(s) more usually involved clinically. Radiographs were made by using the "paralleling" technique. In the second stage, radiographs were made of 83 extracted teeth (22 incisors, 12 canines, and 51 premolars). On the resulting radiographs some prefixed distances were measured. Finally, to gain an anatomic comparison of the values obtained radiologically, 24 of the previously radiographed teeth were sectioned along the sagittal plane at the diameter, and measurements were made and compared with the radiologic data to which the correction coefficients had been applied.

Data Interpretation, Statistical↗
PubMed1982

A clinical study of graphic registration of the condylar path inclination.

The angular values of the CSP registered from 390 patients and obtained by tracing a tangent to the graph with the GR were analyzed. The data subjected to statistical analysis gave a median angular value of the CSP equal to 33 degrees and showed a great median value dispersion. A low error index was obtained in tracing the tangent to the CSP tracing with the GR method. The angular values of the CSP were repeatable over time since the variations found were less than 5 degrees. Variations of the CSP greater than 5 degrees were noted after repeated registrations in patients with TMJ disturbances as well as in patients treated with complete dentures. These data show the necessity for an individual measurement of the CSP value, especially in patients who need extensive readjustments of the prosthesis.

Dental Occlusion↗
PubMedDate not supplied

In vitro evaluation of fit of adhesively luted ceramic inlays.

PURPOSE: The purpose of this study was to evaluate both marginal and overall adaptation of 4 adhesively luted ceramic inlay systems. MATERIALS AND METHODS: A total of 40 extracted teeth were restored with mesio-occlusodistal ceramic inlays using 4 different techniques: Colorlogic, IPS Empress, Celay direct, and Celay indirect. After cementation with a resin luting agent, the samples were sectioned along a mesiodistal line passing through the center of the restoration. The thickness of the cement was measured at the margins and at several points along the inside of the restorations by means of a stereomicroscope fitted with a measuring grid. RESULTS: The results were analyzed by one-way analysis of variance. The marginal precision of IPS Empress and Colorlogic inlays averaged below 50 microns. Marginal precision of Celay inlays averaged between 110 and 130 microns. IPS Empress and Celay inlays showed a uniform distribution of the cement along the entire prepared surface. Colorlogic inlays showed an uneven distribution of the cement film. CONCLUSION: IPS Empress inlays showed the best clinical features compared to Colorlogic and Celay inlays.

Aluminum Silicates↗
PubMedDate not supplied

Evaluation of occlusal contacts in the dental laboratory: influence of strip thickness and operator experience.

PURPOSE: The purpose of this study was to evaluate the influence of recording strip thickness and of operator-dependent factors on the assessment of contact area on a cast mounted on an articulator. MATERIALS AND METHODS: Thirteen dental students and 13 experts (dentists and dental technicians) performed occlusal maneuvers on casts mounted on an articulator, using recording strips of 8- and 40-micron thickness. Contact area, force, and time of biting relative to each group of operators using each type of paper were compared. RESULTS: Both groups obtained significantly greater contact areas with the thicker strip. Students applied significantly stronger but shorter bitings than experts, but obtained smaller contact areas, particularly with the thinner strip. In operators, the extension of contact markings using the 8-micron strip was closely related to the biting time but not to the occlusion force, while neither time nor force of biting had a significant influence when using the 40-micron strip. CONCLUSION: The assessment of occlusal contact in the dental laboratory was significantly influenced by paper thickness, operator experience, biting force, and time. The 40-micron strip was less influenced by operator experience, strength, and duration of biting.

Analysis of Variance↗
PubMedDate not supplied

Comparison of marginal fit of 3 different metal-ceramic systems: an in vitro study.

PURPOSE: The aim of this study was to compare the marginal adaptation of metal-ceramic crowns made with 3 different metal substructures. MATERIALS AND METHODS: Seventy-five gypsum dies were fabricated from a master steel die. They were randomly divided into 3 groups of 25 dies each. A metal coping was prepared on each die using a different technique for each group: composite alloy, electroforming, and cast high-noble alloy. Ceramic was baked on all of the samples following the same protocol and simulating the shape and size of a maxillary central incisor. All specimens were evaluated under a stereomicroscope at 200x magnification. The marginal gap was measured at 8 different points on each specimen before and after ceramic application and also on the master steel die. A total of 3,600 measurements was evaluated. The results were statistically elaborated by means of a t test and one-way analysis of variance (ANOVA). RESULTS: The ANOVA revealed a significant difference in mean marginal gap before and after ceramic application within each group. Electroforming (mean 32 microns) and high-noble alloy (mean 31 microns) showed better marginal fit after ceramic application and on the master steel die compared to composite alloy (mean 68 microns; P < 0.0001). CONCLUSION: Marginal gaps are influenced by the application of ceramic and by the alloy used for the substructure, and the values obtained were within the limits of clinical acceptability (70 microns).

Analysis of Variance↗
PubMedDate not supplied

Influence of posts and cores on light transmission through different all-ceramic crowns: spectrophotometric and clinical evaluation.

PURPOSE: The influence of different types of posts and cores on light transmission through all-ceramic crowns was assessed by spectrophotometric analysis and clinical evaluation. MATERIALS AND METHODS: Three extracted natural teeth were replicated in acrylic resin, with roots prepared to receive standardized posts and cores. Using a silicone impression material as a template, various prosthodontic reconstructions were obtained by combining four types of posts and cores (polished and matte-finished gold alloy, all-ceramic, and ceramized metal alloy) and three types of all-ceramic crowns (IPS-Empress 2 surface-colored, IPS-Empress 2 stratified, and In-Ceram). The spectrophotometric analysis was performed in the dark at 25 degrees C. The teeth were backlit with an incandescent lamp at the color temperature of A illuminant and shielded to avoid spurious light entering the spectrophotometer. The transmitted light was analyzed in terms of luminance at four points of the sample surface (cervical, middle, incisal, and proximal). Twelve measurements were performed for the natural teeth, and 144 were performed for the artificial teeth. RESULTS: Natural teeth had the highest luminance. Among all-ceramic crowns, surface-colored IPS-Empress 2 had the highest luminance, and stratified IPS-Empress 2 had the lowest. Regarding posts and cores, the luminance was highest with the all ceramic, lower with the ceramized and the polished gold alloy (which had very similar luminance), and lowest with the matte-finished gold alloy. No significant difference among prosthodontic combinations was detected under clinical observation. CONCLUSION: The surface-colored glass ceramic (IPS-Empress 2) was the most translucent crown. At the standard crown thickness used, there were small, significant spectrophotometric, but not clinical, differences among the combinations tested. These findings show no esthetic contraindications for the use of polished gold alloy posts and cores with all-ceramic crowns.

Acrylic Resins↗
PubMedDate not supplied

[Occlusion in the etiology of craniomandibular disorders. Current directions].

Craniomandibular disorders are a pathology with a multifactorial genesis where the aetiological aspects it represented by emotional and occlusal factors. These provoke muscular hyperactivity so determining a change in all components of the stomatognathic apparatus. A critical analysis of the literature leads to an analysis of the importance of the occlusal factor in the aetiology of MCD. The conclusions reached are that the ideal occlusion is a theoretical concept. Physiological occlusion is the situation in which, independently of the number, lay-out and relationship between teeth there exists a subjective occlusal stability and a satisfactory masticatory, phonatory and aesthetic function.

Dental Occlusion↗