Ring Liners Research Articles

Comparison of Marginal Fit of Metal Copings in Two Different States with and without Using Ring Liners: An In Vitro Study

To compare the marginal fit of Ni-Cr copings made by casting in two different states (dry and wet) with either cellulose ring liners or no ring liners. An in vitro study was conducted on 40 patterns which were invested, and a burnout casting procedure was used, using a Ni-Cr alloy to obtain the cast copings. The cast copings were divested, cleaned, and run through a finishing procedure. The copings were seated on the stainless steel die and microscopically evaluated for marginal discrepancies at two predetermined reference points using an optical microscope (Rieichert, Austria). Statistical analysis was done using Pearson's correlation coefficient and Chi-square test, keeping 95% confidence intervals and having a p value of less than 0.05 statistically significant. Our results identified marginal discrepancies in all the Ni-Cr cast copings, which significantly differed from each other. The copings obtained from casting with a cellulose ring liner in a wet state showed a significantly higher value followed by casting using a cellulose ring liner in a dry state. The mean marginal discrepancy values were within the clinically acceptable range for all the Ni-Cr cast copings included in two groups. Our study concludes that the copings cast with a cellulose ring liner in dry states had the least amount of vertical marginal discrepancies as compared to those that were cast with a ring liner in two different forms or those cast without a ring liner, suggesting that the use of cellulose ring liner in a dry state is favorable for all casting procedures. Measuring gaps or discrepancies at margins is the commonly used method to determine the fit of Ni-Cr copings. In order to minimize marginal inaccuracies, various authors have suggested different methods to improve the marginal adaptation of cast restorations. There are compensation methods like setting expansion, hygroscopic expansion, and thermal expansion of the investment, which are used to assess metal shrinkage during cooling.

鋳造用リングライナーに関する研究 IX : 乾ライナー法による埋没材の吸水膨張に対する緩衝効果

鋳造用リングライナーに関する研究 IX : 乾ライナー法による埋没材の吸水膨張に対する緩衝効果

The Effect of Casting Ring Liner Length and Prewetting on the Marginal Adaptation and Dimensional Accuracy of Full Crown Castings.

Aim:To evaluate the effect of varying cellulose casting ring liner length and its prewetting on the marginal adaptation and dimensional accuracy of full veneer metal castings.Materials and Methods:The master die was milled in stainless steel to fabricate the wax pattern. Sixty wax patterns were fabricated with a uniform thickness of 1.5 mm at an occlusal surface and 1 mm axial surface, cervical width at 13.5 mm, and 10 mm cuspal height. The samples were divided into six groups (n = 10). Groups I and II samples had the full-length cellulose prewet and dry ring liner, respectively. The groups III and IV had 2 mm short prewet and dry cellulose ring liner, respectively, whereas groups V and VI were invested in 6 mm short ring liner. The wax patterns were immediately invested in phosphate bonded investment, and casting procedure was completed with nickel-chrome alloy. The castings were cleaned and mean score of measurements at four reference points for marginal adaption, casting height, and cervical width was calculated. The marginal adaption was calculated with Imaje J software, whereas the casting height and cervical width was determined using a digital scale. The data was subjected to one-way analysis of varaince and Tukey post hoc statistical analysis with Statistical Package for the Social Sciences version 20 software.Results:The group II had the best marginal adaption with a gap of 63.786 μm followed by group I (65.185 μm), group IV (87.740 μm), and group III (101.455 μm). A large marginal gap was observed in group V at 188.871 μm. Cuspal height was more accurate with group V (10.428 mm), group VI (10.421 mm), and group II (10.488 mm). The cervical width was approximately similar in group I, group III, and group V. Statistically significant difference was observed in Tukey post hoc analysis between group V and group VI with all the other groups with regards to marginal adaptation.Conclusion:The dry cellulose ring liners provided better marginal adaptation in comparison to prewet cellulose ring liners. Accurate cuspal height was obtained with shorter ring liner in comparison to full-length cellulose ring liners.

Development of noncarcinogenic ring liner for dental casting and its basic properties

Although ceramic fiber is widely used in ring liners for dental casting, its carcinogenicity is a matter of concern. We investigated the use of noncarcinogenic biosoluble fiber for ring liners. Plate-shaped biosoluble fiber was modified to obtain the same setting expansion as that of a commercial ring liner as a prototype, and we subjected it to scanning electron microscopic observation, energy-dispersive X-ray spectrometry, X-ray diffraction, and a tensile test. The main components of the prototype were Mg, Si, and O and those of the commercial sample were Al, Si, and O. The prototype and commercial samples were mostly amorphous when not heated, and crystalline components were observed after heating. The tensile strength was significantly different between the prototype and commercial samples, but the difference was small and not problematic with regard to the ring liner strength.

Airborne Asbestos Concentrations of Dental Laboratories in One Metropolitan City

This study was performed to investigate the problems of using asbestos for dental technicians. Samples for analysing were sampled by personal sampler in 40 sampling points of 10 dental laboratories in Daegu city from December 2010 to January 2011 and counted with phase contrast microscopy. The results were as follows: 1. Asbestos concentration(geometric mean) of 40 sampling points in 10 dental laboratories was 0.0061 f/cc and it was under recommended industrial and indoor air standard, but the concentration of asbestos in only two dental laboratories was over indoor recommended standard. 2. The concentration of asbestos in processing room and burnout room was 0.0099 f/cc and 0.0037 f/cc, respectively. 3. The mean concentration(GM) of asbestos by kinds of casting ring liners was 0.0159 f/cc in dental laboratories using industrial asbestos, 0.0104 f/cc in them using asbestos containing ring liners, and 0.0026 f/cc in them using non-asbestos ring liners. Casting ring liners using in dental laboratories should be substituted with non-asbestos liners, because most of dental laboratories were using asbestos containing ring liners and a few of them showed higher concentration than recommended standard.

Casting Ring Liners XVIII : Cushioning Effect of Dry Casting Ring Liners Covering the Casting Ring Inner Surface in Full

Casting Ring Liners XVIII : Cushioning Effect of Dry Casting Ring Liners Covering the Casting Ring Inner Surface in Full

Analysis of the marginal gap of complete crowns made by using wet and dry ceramic ring liners - an in vitro study

The ultimate assessment of cast restoration lies in the accuracy of fit of the casting. Ring liners, through their compressibility, act as a buffer of pliable material between the expanding investment material and the rigid metallic ring. Asbestos, the traditionally used buffer, has now been found to be a potential carcinogen, leading to its withdrawal from use and subsequent introduction of its alternatives i.e. cellulose and ceramic ring liners. This in vitro study was undertaken to evaluate the marginal gap of complete crowns made by using wet and dry ceramic ring liners using a scanning electron microscope. Two groups of thirty castings each were prepared with dry and wet ceramic ring liners respectively and assessed for marginal fit. Results showed that crowns made by using dry ceramic ring liners had significantly less marginal gap as compared to the crowns made by using wet ceramic ring liners.

Casting Ring Liners XV -Cushioning Effect of Casting Ring Liners on the Thermal Expansion of Investment Materials-

Casting Ring Liners XV -Cushioning Effect of Casting Ring Liners on the Thermal Expansion of Investment Materials-

鋳造用リングライナーに関する研究XIII_-_リング内での湿ライナー法による埋没材の硬化膨張に対する緩衝効果_-_

鋳造用リングライナーに関する研究XIII_-_リング内での湿ライナー法による埋没材の硬化膨張に対する緩衝効果_-_

鋳造用リングライナーに関する研究 XIV-空隙率および吸水率について-

鋳造用リングライナーに関する研究 XIV-空隙率および吸水率について-

Casting Ring Liners XIII : Cushioning Effect of Wet Casting Ring Liners on the Setting Expansion of Investment Materials in Casting Ring

Casting Ring Liners XIII : Cushioning Effect of Wet Casting Ring Liners on the Setting Expansion of Investment Materials in Casting Ring

Casting Ring Liners XII : Cushioning Effect of Dry Casting Ring Liners on the Setting Expansion of Investment Material in Solid Metal Ring

Casting Ring Liners XII : Cushioning Effect of Dry Casting Ring Liners on the Setting Expansion of Investment Material in Solid Metal Ring

Casting Ring Liners X : Cushioning Effect of Casting Ring Liners Painted with Petrolatum on the Hygroscopic Expansion of Investment Material

Casting Ring Liners X : Cushioning Effect of Casting Ring Liners Painted with Petrolatum on the Hygroscopic Expansion of Investment Material

Casting Ring Liners VI : IR and WDX Analyses of Liners and Classification into Subgroup

Casting Ring Liners VI : IR and WDX Analyses of Liners and Classification into Subgroup

Casting Ring Liners VII : Physical Properties of Ceramic Fiber Low Temperature Type Liners Coated with Polyethylene Film and Cushioning Effect on the Setting Expansion of Investment Material

Casting Ring Liners VII : Physical Properties of Ceramic Fiber Low Temperature Type Liners Coated with Polyethylene Film and Cushioning Effect on the Setting Expansion of Investment Material

Casting Ring Liners VIII : Cushioning Effect of Casting Ring Liners Painted with Petrolatum on the Setting Expansion of Investment Material

Casting Ring Liners VIII : Cushioning Effect of Casting Ring Liners Painted with Petrolatum on the Setting Expansion of Investment Material

Casting Ring Liners V : The Results of Questionnaires on the Working Condition of the Casting Ring Liner

Casting Ring Liners V : The Results of Questionnaires on the Working Condition of the Casting Ring Liner

Full-Crown Castings Made with Water-Saturated and Dry Casting Ring Liners

Full-Crown Castings Made with Water-Saturated and Dry Casting Ring Liners

Casting Ring Liners IV : Cushioning Effect of Casting Ring Liners Impregnated with a Petrolatum on the Setting Expansion of Investment Material

Casting Ring Liners IV : Cushioning Effect of Casting Ring Liners Impregnated with a Petrolatum on the Setting Expansion of Investment Material

Casting Ring Liners III -Cushioning Effect of Wet Casting Ring Liners on the Setting Expansion of Investment Material-

Casting Ring Liners III -Cushioning Effect of Wet Casting Ring Liners on the Setting Expansion of Investment Material-