scholarly journals An Ultrastructural Study on the Effect of High Temperatures on Teeth and Restorative Materials That Aids in the Identification of Human Remains

2021 ◽  
Vol 2021 ◽  
pp. 1-6
Author(s):  
V. Yashoda ◽  
Manay Srinivas Munisekhar ◽  
S. Shylaja ◽  
Krishna A. Rao ◽  
Sharath Kumar Reddy ◽  
...  
Keyword(s):  
High Temperatures ◽  
Elemental Analysis ◽  
Naked Eye ◽  
Dental Restorations ◽  
Good Imaging ◽  
Metal Ceramic ◽  
Restorative Materials ◽  
Different Temperatures ◽  
Ceramic Crowns ◽  
Crown Preparation

Introduction. In most disasters, teeth are the only means of positive identification of an otherwise unrecognizable body, as there has been tremendous increase in the use of dental restorations that have different resistance to prolonged high temperature which is an important aid in identifying burned victims. Application of SEM/EDS in forensics was found useful in areas where there is a need for good imaging with high magnification combined with elemental analysis. The objective of this study was to analyze incineration effects on teeth and restorative materials using SEM/EDS. Materials and Method. 128 extracted teeth were collected, 96 were restored with silver amalgam, composite, and GIC of 32 each, and crown preparation was done in 32 teeth for which metal ceramic crowns were prepared. These teeth were subjected to 4 different temperatures (500°C, 700°C, 900°C, and 1100°C) for 20 minutes, and they were analyzed macroscopically and by using SEM for the changes subsequent to their exposure to such high temperatures. Results. All the restorations which were very difficult to identify by naked eye were identified with the help of SEM/EDS. Conclusion. Elemental analysis of the specific restorative material proves to be an essential tool for the forensic odontologist.

Analysis of Internal and Marginal fit of Metal-ceramic Crowns During Processing, Using Conventional and Digitized Technologies

2018 ◽  
Vol 69 (7) ◽  
pp. 1699-1701
Author(s):  
Cristina Elena Savencu ◽  
Sorin Porojan ◽  
Liliana Porojan
Keyword(s):  
Clinical Success ◽  
Replica Technique ◽  
Digital Light Processing ◽  
Marginal Fit ◽  
Dental Restorations ◽  
Metal Ceramic ◽  
Ceramic Crowns ◽  
Internal Fit ◽  
Pattern Group

Copings accuracy is an important factor for long-term clinical success of ceramic fused to metal dental restorations. The purpose of the study was to investigate marginal and internal fit of metal-ceramic crowns during processing, using conventional and digitized technologies. Metal copings were produced by Digital light Processing (DLP), invested and casted. Ceramic veneers were overpressed. Internal and marginal fit was measured using silicon replica technique for patterns, casted frameworks and final ceramic fused to metal crowns. Best adaptation was found in resin-pattern group, with small increasing of gap after casting and after ceramic pressing.

scholarly journals Influence of metal-ceramic fixed dental restorations on the occurrence of discoloration of gingiva

2006 ◽  
Vol 63 (4) ◽  
pp. 409-413 ◽  
Author(s):  
Ljubisa Ristic ◽  
Srbislav Ilic ◽  
Aleksandar Zivanovic
Keyword(s):  
Histopathological Examination ◽  
Atomic Absorption Spectrophotometry ◽  
Gingival Tissue ◽  
Dental Restorations ◽  
Metal Contents ◽  
Metal Ceramic ◽  
Therapeutic Procedures ◽  
Cast Alloys ◽  
Ceramic Crowns ◽  
Dental Cast

Background. Adverse effects of dental cast alloys on the health of patients are the problem in clinical practice. The aim of this paper was to describe the case of a patient with discolorated gingivae in the presence of fixed dental restorations and used diagnostic and therapeutic procedures. Case report. A 30-year old patient, presented with the complaints about unsatisfactory esthetic of his fixed dental restorations. He complained about the greyish discoloration of gingivae, inappropriate color of the crowns, and a larger space between the central incisors. Both discolorated and normal gingivae around the fixed dental restorations were taken by excision and the samples of gingivae were examined histopathologically, and by using the Atomic Absorption Spectrophotometry test (AAS). Histopathological examination of the discolorated gingivae showed the presence of non-specific inflammation with a foreign body. AAS revealed the presence of various metals in the samples and the higher metal contents in the samples of discolorated gingivae as compared with the samples of normal gingivae. New metal-ceramic crowns were made for the patient. Conclusion. A main cause of greyish discoloration of gingivae was presence of a metal in gingival tissue. After the excision of discolorated gingivae old metalceramic crowns should be replaced with new crowns.

Assessment of the compressive strength of the metal-ceramic connections in fixed dental restorations

2016 ◽  
Vol 79 (2) ◽  
pp. 66-73
Author(s):  
P. Malara ◽  
K. Paluch ◽  
K. Sobolewska ◽  
A. Pasieka
Keyword(s):  
Compressive Strength ◽  
Compression Test ◽  
Hardness Test ◽  
Good Option ◽  
Static Compression ◽  
Dental Restorations ◽  
Metal Ceramic ◽  
Ceramic Crowns ◽  
Scanning Electron ◽  
Artificial Tooth

Purpose: The purpose of the work was to evaluate the compressive strength of metalceramicconnections in the fixed dental restorations.Design/methodology/approach: Restorations were made on a model of the naturalpatient's dentition which was developed specifically for this study. The study included 10metal - porcelain crowns, for each group of teeth. Their production used Remanium 2000+alloy and porcelain Vita VMK Master. A static compression test was carried out on the finalcrowns and Vicker's hardness test was performed. Visual observations were carried out ona scanning electron microscope.Findings: On the basis of the research and the discussion it was possible to concludethat metal-porcelain crowns have a greater compressive strength than natural human teeth.Thus, they are more resistant to occlusal forces and the crowns for the first molars are thestrongest restorations.Practical implications: The metal-porcelain crowns are a very good option for teethrestoration and they can be used even in the areas of the mouth where the occlusal forcesreach the maximum values.Originality/value: The article focuses on testing of compressive strength of metal-ceramiccrowns. The comparison with natural human occlusal forces shows the sufficient mechanicalproperties of metal-ceramic crowns for application in humans. The artificial tooth geometryallows applying prosthetic crowns in the patient's mouth without the risk of ceramic breakdown.

scholarly journals Hydrothermal Ageing and Its Effect on Fracture Load of Zirconia Dental Implants

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3103
Author(s):  
Laurent Gremillard ◽  
Agnès Mattlet ◽  
Alexandre Mathevon ◽  
Damien Fabrègue ◽  
Bruno Zberg ◽  
...  
Keyword(s):  
Dental Implants ◽  
Fracture Load ◽  
Accelerated Ageing ◽  
Dental Ceramics ◽  
X Ray Diffraction ◽  
X Ray ◽  
Dental Restorations ◽  
Different Temperatures ◽  
Mechanical Performances ◽  
Kinetics Of

Due to growing demand for metal-free dental restorations, dental ceramics, especially dental zirconia, represent an increasing share of the dental implants market. They may offer mechanical performances of the same range as titanium ones. However, their use is still restricted by a lack of confidence in their durability and, in particular, in their ability to resist hydrothermal ageing. In the present study, the ageing kinetics of commercial zirconia dental implants are characterized by X-ray diffraction after accelerated ageing in an autoclave at different temperatures, enabling their extrapolation to body temperature. Measurements of the fracture loads show no effect of hydrothermal ageing even after ageing treatments simulated a 90-year implantation.

Influence of Heat on Seed Germination of Cistus Laurifolius and Cistus Ladanifer

1992 ◽  
Vol 2 (1) ◽  
pp. 15 ◽  
Author(s):  
L Valbuena ◽  
R Tarrega ◽  
E Luis
Keyword(s):  
Seed Germination ◽  
High Temperatures ◽  
Exposure Time ◽  
Germination Rate ◽  
Heat Exposure ◽  
Cistus Ladanifer ◽  
Different Temperatures ◽  
Petri Dishes ◽  
Germinated Seeds

The influence of high temperatures on germination of Cistus laurifolius and Cistus ladanifer seeds was analyzed. Seeds were subjected to different temperatures for different times, afterwards they were sowed in plastic petri dishes and monitored for germinated seeds over two months.The germination rate observed in Cistus ldanifer was greater than in Cistus laurifolius. In both species, heat increased germination percentages. For Cistus laurifolius higher temperatures or longer exposure times were needed. Germination percentages of Cistus ladanifer were lower when heat exposure time was 15 minutes.It must be emphasized that germination occurred when seeds were not treated, while seeds exposed to 150�C for 5 minutes or more did not germinate.

Fit of metal ceramic crowns cast in Au-1.6wt% Ti alloy for different abutment finish line curvature

2006 ◽  
Vol 22 (5) ◽  
pp. 397-404 ◽  
Author(s):  
Jianxiang Tao ◽  
Masanobu Yoda ◽  
Kohei Kimura ◽  
Osamu Okuno
Keyword(s):  
Ti Alloy ◽  
Finish Line ◽  
Metal Ceramic ◽  
Ceramic Crowns

PROSPECTS FOR MANUFACTURING FRAMES OF METAL CERAMIC STRUCTURES OF DENTAL PROSTHESES BY THE METHOD OF SELECTIVE LASER SINTERING

2021 ◽  
pp. 232-239
Author(s):  
Stepanov V.A. ◽  
Shemonaev V.I. ◽  
Buyanov E.A. ◽  
Grachev D.V. ◽  
Parchomenko A.N. ◽  
...  
Keyword(s):  
Objective Assessment ◽  
Selective Laser Sintering ◽  
Clinical Effectiveness ◽  
Study Groups ◽  
Laser Sintering ◽  
Dental Prostheses ◽  
Metal Ceramic ◽  
Abutment Teeth ◽  
Ceramic Crowns ◽  
Solid Tissues

The article presents the results of evaluating the prototyping of metal-ceramic structures made by casting and selective laser sintering. To achieve this goal, 27 patients with fabricated metal-ceramic crowns and bridgeworks were examined. Two study groups were created. The first group included 14 patients for whom dental prosthesis frameworks were made by casting. The second group consisted of 13 people, for whom the frames of dentures were made by the method of selective laser sintering. The analysis of clinical effectiveness was carried out according to the following criteria: 1- precision of the felling of prosthesis frame to solid tissues of abutment teeth; 2- the condition of the marginal periodontium; 3- the integrity of the ceramic cladding. The results of the study showed that the precision to solid tooth tissues of metal-ceramic dental prostheses made by laser selective sintering is higher than of frames made by casting. In accordance to the second criteria the best results were also shown by the participants of the second group. No chipping of the ceramic veneer from the metal-ceramic denture frameworks made by laser selective sintering was found. Thus, dentures which frameworks are made by the method of selective laser sintering are characterized by a higher objective assessment of their precision to the solid tissues of the abutment teeth. Lesions of the marginal periodontium both inflammatory and dystrophic were less in the participants of the second group. The frequency of defects in the coating of metal-ceramic dentures was significantly lower in the case of fabrication frameworks by laser selective sintering.

Linear and non-linear analysis on two-dimensional steel frame under different temperatures

2019 ◽  
Vol 10 (1) ◽  
pp. 48-55
Author(s):  
Parthasarathi N. ◽  
Satyanarayanan K.S. ◽  
Prakash M. ◽  
Thamilarasu V.
Keyword(s):  
High Temperatures ◽  
Progressive Collapse ◽  
Transient State ◽  
Steel Frame ◽  
Frame Structure ◽  
Two Dimensional ◽  
Content Type ◽  
Frame Building ◽  
Different Temperatures ◽  
Steel Frame Structure

Purpose Progressive collapse because of high temperatures arising from an explosion, vehicle impact or fire is an important issue for structural failure in high-rise buildings. Design/methodology/approach The present study, using ABAQUS software for the analysis, investigated the progressive collapse of a two-dimensional, three-bay, four-storey steel frame structure from high-temperature stresses. Findings After structure reaches the temperature results like displacement, stress axial load and shear force are discussed. Research limitations/implications Different temperatures were applied to the columns at different heights of a structure framed with various materials. Progressive collapse load combinations were also applied as per general service administration guidelines. Originality/value This study covered both steady-state and transient-state conditions of a multistorey-frame building subjected to a rise in temperature in the corner columns and intermediate columns. The columns in the framed structure were subjected to high temperatures at different heights, and the resulting displacements, stresses and axial loads were obtained, analysed and discussed.

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