Metal Inlays Research Articles

Influence of Thermomechanical Loads on the Corrosion Behavior of Metal-Polymer-Joints

Metal-polymer-joints can be found in multiple today’s major applications like in hybrid car parts in terms of lightweight construction or molded electrical contacts for high-voltage applications. Common to both is the harsh environment they are exposed to including elevated temperature changes inducing thermomechanical stresses based on the differences of the CTE values as well as corrosive media like salty water, solvents or electrolytes. Each promotes its own corrosion mechanism that in most cases comes along with a degradation of the material’s and therefore the part’s performance in service. Especially, two mechanisms have to be considered when dealing with corrosion of metal-polymer-joints. Firstly, corrosion processes of metal and polymer can influence each other as well as the metal-polymer interface layer depending on the material combination. Secondly, thermomechanical stress due to temperature changes can also have an effect on the material’s corrosion behavior. Studying both mechanisms would help to improve the service time of hybrid parts.The work introduces a new method to investigate corrosion processes in metal-polymer-joints combining the influence of corrosive media and thermomechanical load. A hybrid specimen consisting of a specially formed metal inlay fully surrounded by a potting polymer is used for the measurements. When exposed to cyclic temperature load in a test chamber mechanical stress is induced in the polymer due to the different CTE of the materials. For the measurements typical material combinations used in lightweight construction and high-voltage applications are used. The hybrid specimens are exposed to thermal shocking cycles while being fully surrounded by corrosive media. Throughout the experiment, the specimens are constantly monitored using electrochemical impedance spectroscopy (EIS). In addition, a visual inspection of the specimens takes place after certain times to analyze the overall condition and possible cracks. As a reference, the same setup is applied only to the metal inlays used in the hybrid specimens. By interpreting the results of the EIS measurements, possible corrosion processes of metal and polymer as well as their correlation can be characterized in detail. Additionally, the comparison of hybrid specimens and raw metal inlays reveals the influence of the thermomechanical load on the corrosion process. The experimental part is supported by FE-simulations, which are also supplementary presented in this investigation.

Accuracy Assessment of Pedicle and Lateral Mass Screw Insertion Assisted by Customized 3D-Printed Drill Guides: A Human Cadaver Study.

Accurate cervical screw insertion is of paramount importance considering the risk of damage to adjacent vital structures. Recent research in 3-dimensional (3D) technology describes the advantage of patient-specific drill guides for accurate screw positioning, but consensus about the optimal guide design and the accuracy is lacking. To find the optimal design and to evaluate the accuracy of individualized 3D-printed drill guides for lateral mass and pedicle screw placement in the cervical and upper thoracic spine. Five Thiel-embalmed human cadavers were used for individualized drill-guide planning of 86 screw trajectories in the cervical and upper thoracic spine. Using 3D bone models reconstructed from acquired computed tomography scans, the drill guides were produced for both pedicle and lateral mass screw trajectories. During the study, the initial minimalistic design was refined, resulting in the advanced guide design. Screw trajectories were drilled and the realized trajectories were compared to the planned trajectories using 3D deviation analysis. The overall entry point and 3D angular accuracy were 0.76±0.52 mm and 3.22±2.34°, respectively. Average measurements for the minimalistic guides were 1.20 mm for entry points, 5.61° for the 3D angulation, 2.38° for the 2D axial angulation, and 4.80° for the 2D sagittal angulation. For the advanced guides, the respective measurements were 0.66 mm, 2.72°, 1.26°, and 2.12°, respectively. The study ultimately resulted in an advanced guide design including caudally positioned hooks, crosslink support structure, and metal inlays. The novel advanced drill guide design yields excellent drilling accuracy.

Archaeometallurgical investigation of metal wares from the medieval Iranian world (10th-15th centuries): The ISLAMETAL project

The ISLAMETAL project (2013–2017) was jointly conducted by the Département des Arts de l’Islam (DAI), Musée du Louvre, and the Centre de Recherche et de Restauration des Musées de France (C2RMF) and kindly supported by the Roshan Cultural Heritage Institute (RCHI). The project deals with the detailed technological investigation of copper-based metal wares (10th to late 15th centuries CE) from the Iranian world at the Louvre Islamic Art collection, comprising mostly household and domestic objects such as candlesticks, lamps, ewers, plates, and bowls. Amongst the collection characteristic qualities of production and decoration can be discerned. High status objects were decorated with sophisticated patterns including exquisite chasing, engraving, champlevé, and especially copper, silver and gold inlays. Results of the technological investigation of some 169 objects (particle induced X-ray emission, inductively coupled plasma atomic emission spectroscopy, digital microscopy, X-radiography) showed a range of distinct alloy types employed and a correlation between artefact typology, fabrication technique, status and alloys. Decoration techniques showed a clear change spanning the 10th and 15th centuries with the notable introduction of precious metal inlays during the 12th century and new inlaying techniques before the mid-13th century. Lost-wax casting was the preferred manufacturing method even for mass produced objects where sand casting would seem a more suitable choice. Specific production centres in the region of Khorasan, such as that of Herat and Ghazna, were possible to be technologically identified. Detailed investigation of this comprehensive corpus provided for the first time key technical references for further comparison, particularly with neighbouring Near Eastern workshops.

Determination of Pt, Pd and Rh in Brassica Napus using solid sampling electrothermal vaporization inductively coupled plasma optical emission spectrometry

Conventional approaches for the analysis of platinum group elements (PGEs) in plant material suffer from sample digestion which results in sample dilution and therefore requires high sample intakes to maintain the sensitivity. The presented solid-sampling method avoids sample digestion while improving sensitivity when compared to digestion-based inductively coupled plasma optical emission spectrometry (ICP-OES) methods and allows the analysis of sample masses of 5mg or less. Detection limits of 0.38μgg−1, 0.14μgg−1 and 0.13μgg−1 were obtained for Pt, Pd and Rh, respectively using a sample intake of 5mg. The reproducibility of the procedure ranged between 4.7% (Pd) relative standard deviation (RSD, n=7) and 7.1% (Rh) RSD for 25ng analytes. For quantification, aqueous standards were applied on paper filter strips and dried. Only the dried filters were introduced into the electrothermal vaporization unit. This approach successfully removed memory-effects observed during analysis of platinum which occurred only if liquid standards came into contact with the graphite material of the furnace. The presented method for overcoming the Pt-memory-effects may be of further interest for the analysis of other carbide-forming analytes as it does not require any technical modification of the graphite furnace (e.g., metal inlays, pyrolytic coating). Owing to lack of suitable certified reference materials, the proposed method was compared with conventional ICP-OES analysis of digested samples and a good agreement was obtained. As a result of the low sample consumption, it was possible to determine the spatial distribution of PGEs within a single plant. Significant differences in PGE concentrations were observed between the shoots (stem, leaves) and the roots. Pd was mainly found in the roots, whereas Pt and Rh were also found in higher concentrations in the shoots.

Development of artificial black patina on Mycenaean metal finds

Artificially black patinated finds from Mycenaean contexts are among the most interesting Bronze Age metal objects. They come from several contexts in the Eastern Mediterranean and are important because of their technology and as indication of trade and cultural connections. Regrettably only few examples of items of this material have been scientifically examined. Archaeologists without a scientific background are still not aware of the true nature of the black material with precious metal inlays. This paper presents a research on the development of the patina on a Mycenaean dagger and on the famous silver cup from Enkomi in Cyprus. The alloys employed for the black inlays, analysed up to now, consist of Cu containing low amounts of Au that was artificially patinated by different methods: either the red hot object was plunged into an aqueous solution containing copper salts and alum or it was heated in the boiling solution.

Finite Element Stress Analysis of Cast Metal Inlays Restored Posterior Teeth

ABSTRACTCast metal inlays have overall characteristics unavailable in any other restorative procedure, including low restoration wear, low wear of opposing teeth, lack of breakage, burnishability, malleability, and proven long term service. They replace missing teeth structures, without doing anything to reinforce the remaining structures. Stress concentrations can manifest themselves in various forms of failures. The aim of the study was to investigate the effect of preparation design on stress distribution in molars with different class II preparations and restored with cast metal inlays.3D models of premolars and molars were created: intact teeth, unrestored teeth with class II preparations with different tapers (between 0 and 10 degree); the same teeth restored with metalic inlays. The geometries of the intact teeth were obtained by 3D scanning using a manufactured device. With Rhinoceros modeling program the preparations and the appropriately inlays were designed. These were exported in Ansys finite element analysis software for structural simulations. Stresses were registred around the occlusal contact areas. For the studied cases, the stress values were not significant influenced by the taper of the preparation. In the teeth restored with cast metal inlays, the von Mises equivalent stress values were similar to those in the intact tooth.From biomechanical point of view, it was demonstrated that class II cast metal inlays on posterior teeth restore the original strength of the teeth. Taking into account the other characteristics of these restorations, they remain the standard of care for long-term rehabilitations. A taper between 0 and 10 degree of the preparation is not decisive for the stress values.

Projection-Based Metal-Artifact Reduction for Industrial 3D X-ray Computed Tomography

Multi-material components, which contain metal parts surrounded by plastic materials, are highly interesting for inspection using industrial 3D X-ray computed tomography (3DXCT). Examples of this application scenario are connectors or housings with metal inlays in the electronic or automotive industry. A major problem of this type of components is the presence of metal, which causes streaking artifacts and distorts the surrounding media in the reconstructed volume. Streaking artifacts and dark-band artifacts around metal components significantly influence the material characterization (especially for the plastic components). In specific cases these artifacts even prevent a further analysis. Due to the nature and the different characteristics of artifacts, the development of an efficient artifact-reduction technique in reconstruction-space is rather complicated. In this paper we present a projection-space pipeline for metal-artifacts reduction. The proposed technique first segments the metal in the spatial domain of the reconstructed volume in order to separate it from the other materials. Then metal parts are forward-projected on the set of projections in a way that metal-projection regions are treated as voids. Subsequently the voids, which are left by the removed metal, are interpolated in the 2D projections. Finally, the metal is inserted back into the reconstructed 3D volume during the fusion stage. We present a visual analysis tool, allowing for interactive parameter estimation of the metal segmentation. The results of the proposed artifact-reduction technique are demonstrated on a test part as well as on real world components. For these specimens we achieve a significant reduction of metal artifacts, allowing an enhanced material characterization.

Stresses in Cast Metal Inlays Restored Molars

Stresses in Cast Metal Inlays Restored Molars

Analysis of an administrative database of indirect restorations over 11 years

Aim This paper describes the database used to assess the survival of indirect restorations and presents general data on survival of these restorations. Methods Data, based on the complete attendance and treatment history, over the 11 years from 1991 to 2001, of a statistically representative sample of 23,165 General Dental Services’ (GDS) patients in England and Wales, all of whom received at least one indirect restoration during the observation period, have been analysed. The patients on the database received a total of 36,397 courses of treatment, and there were 52,481 indirect restorations placed. The method of analysis involved the estimation of the probability that the patient will eventually return, given an interval without attending, by analysing the observed patterns of re-attendance. This estimated probability of re-attendance was then used to modify the standard Kaplan–Meier procedure to produce realistic estimates of the hazard of re-intervention. Results Overall, 75% of indirect restorations remained without re-intervention after 5 years, and 61% after 10. Crowns outperformed other types of indirect restoration. Multi-surface metal inlays, by contrast, had a median interval to re-intervention of less than 8 years. Conclusions The times to re-intervention for different types of indirect restoration have been successfully estimated and crowns shown to outperform veneers and inlays.

Clinical Survey on Type of Restoration in Deciduous Teeth

This study was conducted in 533 children with 1,634 treated teeth who visited the Pediatric Dentistry Department at the Chiba Hospital of Tokyo Dental College between January and December, 2003. Restorations on deciduous tooth were categorized by age of patient and tooth type. The following observations were made: Children aged 4 (17.9%) visited the clinic most frequently and this group had the highest number of deciduous restorations (21.3%). Among the 1,634 deciduous teeth restored, metal inlays were provided in 29.4% of total teeth restored, composite resin restorations in 27.2%, stainless-steel crowns in 25.7%, composite resin full crowns in 7.7%, glass-ionomer cement restorations in 6.6%, and amalgam restorations in 3.4%. By age, composite resin was most frequently used in children aged 1 to 3. In children aged 5 to 9, metal inlay was most frequently used. Those aged 4 received mostly stainless-steel crowns. Composite resin restorations were used mostly in anterior deciduous teeth, and metal inlays mostly in deciduous molars. Previous research indicated an increasing trend towards composite resin restorations and composite resin full crowns. The present study also confirmed such a trend. While the use of metal inlays and stainless-steel crowns tended to increase until 1987, the present study indicated a trend to decrease.

深在性う蝕の裏層が鋳造歯冠修復物の辺縁漏洩に及ぼす影響

This study investigated the effect of a cavity lining on marginal leakage of a cast restoration. MOD cavities were prepared on human extracted upper third molars. Additional hemispherical cavities (1.6 mm diameter), simulating deep caries, were prepared on axial walls, and they were restored with lining materials including a glass-ionomer, a resin-modified glass-ionomer, and a low viscosity composite for a lined group. Metal inlays were cast with a 12% Au-Ag-Pd alloy and luted with four luting agents including a zinc phosphate(HZ), a conventional glass ionomer (FI), a resin-modified glass ionomer (VL), and an adhesive resin (SB). The specimens were stored in 37 degrees C distilled water for 24 hours and subjected to 5,000 thermo-cycles, and then, dye penetration was evaluated after 24 hr immersion in 2% erythrosine solution. Metal disks were luted to dentin disks, which have the same-sized spherical cavities in the central area, with the same luting agents. Shear bond strengths were evaluated for both lined and non-lined specimens after the same storing and thermo-cycle processes. The inlay specimens luted with SB exhibited no dye penetration, while the specimens luted with HZ presented dye penetration reaching to the pulp chamber. The specimens luted with FI and VL showed moderate dye penetration and the values of dye penetration for the cavity-lined group were significantly less compared to those for the lined group (p<0.05). The shear bond strength of the specimens luted with SB and VL was significantly affected by the lining material. The shear bond strength of the specimens luted with HZ or FI was 0 MPa. The marginal leakage of a cast restoration is affected by the cavity lining but can be improved by using adhesive resin.

Sandblasting of Inlay Margin-Marginal Abrasion and Bond Strength-

Specimens (such as metal inlays) with 30 degrees or 45 degrees marginal bevel were prepared by casting with a 12% Au-Pd-Ag alloy or a gold alloy. A form of the marginal bevel was traced on a profile projector before and after sandblasting, and the length of the abraded margin measured. All the blasting conditions abraded the marginal bevel, while the blasting at 20 mm for 2 seconds brought about the least abrasion of approximately 10 microm in the 45 degrees specimen cast with Au-Pd-Ag alloy. The gold alloy specimens were abraded more than the Au-Pd-Ag alloy ones; those with marginal bevel of 30 degrees were abraded more than those of 45 degrees. On the other hand, the effect of different blasting conditions on the bond strength of units bonded with resin cement was evaluated (under selected blasting conditions known to cause relatively less damage to the marginal level). Specimens treated by sandblaster exhibited a comparable tensile bond strength, while specimens without sandblasting but applied with only an alloy primer showed a statistically low value.

Cavity preparation for metal inlay by experimental tip for Er:YAG laser

The dental Er:YAG laser which is mainly used for dental hard tissue cutting was recently developed. In restorative dentistry, this laser has usually been used in composite resin restoration, but not for cast metal inlay restoration. This is because it is difficult to make the cavity form, such as retention form and convenience form, by using laser irradiation. At the 6th ISLD meeting, we reported an experimental chisel-shaped contact tip (ECSC tip) for use in cavity preparation for cast metal inlays. In this study, we examine a newly developed, modified experimental tip in inlay cavity preparation using an Erwin (ML22:HOYA & MORITA). This tip is composed of an arrangement of seven optical fibers having 0.2 or 0.3 mm diameter in a single row. The tooth-cutting efficacy of this tip was examined using extracted human and bovine teeth, and the irradiated sites were observed with SEM. The cutting efficacy of the experimental tip for both enamel and dentin was better than that of the ECSC tip. However, the surface flatness after cutting using experimental tip was poorer than the of the ECSC tip. It is suggested that inlay cavity preparation is possible using Erwin with this tip.

Effects of metal-inlay thickness in polyethylene cups with metal-on-metal bearings.

A way to prevent polyethylene wear in total hip replacements is to use metal-on-metal bearings. The cup design of these bearings may be a metal inlay in a polyethylene cup. However, these metal inlays are relatively thin and may deform on loading. The purpose of the current study was to determine whether these potential problems become actual for a realistic range of metal-inlay components having a thickness greater than 1 mm. For this purpose, the effects of thickness variation of a metal inlay in an ultrahigh molecular weight polyethylene cup were determined using three-dimensional finite element techniques. The results showed no indications for jamming of the bearing assuming a realistic inlay thickness (3-5 mm), even with a small clearance (25 microm). The metal inlay acted rigidly beyond a thickness of approximately 5 mm. Metal inlays thinner than 1.5 mm led to a considerable increase in contact area and a reduction in contact peak stress, which may be beneficial for the bearing performance. Currently, these thin liners have too many unknown characteristics and therefore the current authors recommend using rigid metal liners that have a thickness greater than 5 mm.

Posterior bridges retained by resin-bonded cast metal inlay retainers: a report of 60 cases followed for 6 years.

Between May 1989 and July 1994, 60 adhesive fixed partial posterior dentures retained by resin-bonded cast metal inlays were placed under controlled conditions. The influence of various prognostic factors on the event free and overall service duration was investigated with univariate and multivariate analysis. The majority of the failures (16 of 18) were caused by loss of adhesion at the metal cement interface and were observed either as debonding of the restorations completely or dislodgement of a single retainer. The other two failures appeared as secondary caries. Univariate analysis demonstrated that, retainer type, approximal configuration and dentine exposition had no effect on the event free service duration. On the other hand, gingival finishing level and luting agent were found to have an effect. Univariate testing was also conducted for the overall service duration and none of the variables were found to have an effect. Multivariate Cox Regression Analysis was performed to estimate the influence of categorical covariates: type of retainer, approximal preparation modification, gingival finishing level, preparation depth and luting agent on survival rates of event free and overall service duration. Luting agent was found to be the single independent prognostic variate (P < 0.0001) for the event free service duration and the other covariates were rejected. For overall service duration, none of the variables were found to be effective.

Posterior bridges retained by resin‐bonded cast metal inlay retainers: a report of 60 cases followed for 6 years

summary Between May 1989 and July 1994, 60 adhesive fixed partial posterior dentures retained by resin‐bonded cast metal inlays were placed under controlled conditions. The influence of various prognostic factors on the event free and overall service duration was investigated with univariate and multivariate analysis. The majority of the failures (16 of 18) were caused by loss of adhesion at the metal cement interface and were observed either as debonding of the restorations completely or dislodgement of a single retainer. The other two failures appeared as secondary caries. Univariate analysis demonstrated that, retainer type, approximal configuration and dentine exposition had no effect on the event free service duration. On the other hand, gingival finishing level and luting agent were found to have an effect. Univariate testing was also conducted for the overall service duration and none of the variables were found to have an effect, Multivariate Cox Regression Analysis was performed to estimate the influence of categorical covariates: type of retainer, approximal preparation modification, gingival finishing level, preparation depth and luting agent on survival rates of event free and overall service duration. Luting agent was found to be the single independent prognostic variate (P &lt; 0·0001) for the event free service duration and the other covariates were rejected. For overall service duration, none of the variables were found to be effective.

The Effect of Test Environment on the Creep of Base Metal Surface Films Over Precious Metal Inlays

An evaluation of two precious-metal inlays, WE Hash 1 (69Au25Ag6Pt) and diffused gold-palladium-silver, in combination with several base metals (C72500, C52100, C65400, C17200), which were exposed to a range of severe environments, is discussed. The materials were exposed as (a) bare coupons and (b) assembled connectors. The environmental exposures were carried out in a laboratory test chamber using Battelle Class II and III atmospheres, respectively. The chamber test periods simulated outdoor life exposures of 2-20 yr for Battelle Class II and 1-10 yr for Battelle Class III. Sample coupons and connectors are characterized by measurements of contact and low-level circuit resistance, respectively. The beneficial effects of a protective layer over copper alloys to prevent creep of corrosion products were demonstrated. Two methods, the use of a commercial lubricant and the shielding of a connector housing, were used to retard corrosive attack and creep.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

The effect of test environment on the creep of base metal surface films over precious metal inlays

An evaluation of two precious-metal inlays, WE Hash 1 (69Au25Ag6Pt) and diffused gold-palladium-silver, in combination with several base metals (C72500, C52100, C65400, C17200), which were exposed to a range of severe environments, is discussed. The materials were exposed as (a) bare coupons and (b) assembled connectors. The environmental exposures were carried out in a laboratory test chamber using Battelle Class II and III atmospheres, respectively. The chamber test periods simulated outdoor life exposures of 2-20 yr for Battelle Class II and 1-10 yr for Battelle Class III. Sample coupons and connectors are characterized by measurements of contact and low-level circuit resistance, respectively. The beneficial effects of a protective layer over copper alloys to prevent creep of corrosion products were demonstrated. Two methods, the use of a commercial lubricant and the shielding of a connector housing, were used to retard corrosive attack and creep. >

Monitoring, Controlling, and Resolving Connector-Related Concerns

lnterconnection components like connectors, pins, and printed wiring board fingers are usually required to satisfy manufacturers and/or users specifications prior to being used. This entails monitoring such components for quality and, if necessary, controlling or resolving problems that arise. The following examples of such situations are discussed: 1) incoming material inspection procedures for monitoring quality of precious metal inlays used as contact finish, involving contact resistance measurements; 2) pass-fail requirement testing and demerit rating of discolored pins with electroplated gold finishes; 3) cleaning procedure for excessive lubricant in contact area; 4) controlling for uniformity in coverage of lubricant on contact areas; 5) resolving resistance failure of pins from solder reflow contamination with proper cleaning and production procedures; and 6) resolving resistance failure of connector contacts by using such analytical techniques as laser mass spectroscopy and gas chromatograph mass spectroscopy to detect failure mode and develop cleaning procedures.

Reliability of Clad Metal Inlays for Electrical Connectors

Following the prior publication [ 1 ], we tested more connector hardware of clad metal inlays the quality of which is quite close to the production level. In other words, the spring base material was all made of beryllium copper fully heat-treated after forming. The springs were punched and formed with a production the spring gaps were more uniform and all within the specified range, though in the high end. The inlay materials used in this extended test were: a) 18K Au (75Au25Ag), b) pure palladium (100 Pd), c) Alloy 69Au25Ag6Pt, d) 60Pd40Ag alloy, and e) alloy-55(55Au39Ag3Cd31n). These materials were reported to have relatively better performance among the many candidates we initially studied. The sample size used in these tests was much larger than the previous one; as a result, the experimental data are more reliable and meaningful. Two groups of connector hardware representing today's highdensity miniature electronic packaging were used. One group was the cylinder-cylinder contact, the other was the cylinder-flat contact. Also some discussion was devoted to the dimple-flat contact system. The contact-resistance data were collected over a period of 6 months to 1 year from three kinds of environmental tests. Both porosity and formability were acceptable for all the inlay springs. No wear-through contacts were found after 50 insertions with lubricant applied on the Au or Pd plated pins. All five inlay materials tested behaved almost equally well in their contact-resistance measurements. Previously the 69Au25Ag6Pt was chosen as the best, and the palladium stood as the second best at that time. However, in this paper we have shown that the Pd is clearly the winner in many aspects of the tests. The 69Au25Ag6Pt is equivalent to the 75Au25Ag alloy as the second best choice.