Wax Technique Research Articles

Technological aspects in manufacturing of aesthetic prosthetic restorations with metal infrastructure

Restoring the morphology and functionality of dental arches affected by carious lesions and/or edentations using fixed prosthetic restorations has been a continuous challenge for dentists. Porcelain fused to metal prosthetic restorations using lost wax technique or modern digital methods have proven to be a useful tool in restoring aesthetics and mastication, aspects that lead to the social reintegration of patients. The natural aspect of the prosthetic restoration depends on the talent and inspiration of the dental technician as the art of layering of ceramic masses cannot be surpassed by new emerging technologies.

Comparing the trueness of 3D printing and conventional casting for the fabrication of removable partial denture metal frameworks for patients with different palatal vault depths: An in vitro study

Statement of problemThe success of a removable partial denture depends on its fit, and, with conventional casting, the framework is more distorted in patients with a deep palatal vault. Questions remain about whether the three-dimensional (3D) printing technique for fabricating a framework can improve the accuracy of fit for these patients. PurposeThe purpose of this in vitro study was to compare the trueness of metal frameworks fabricated by selective laser melting, 3D printing pattern casting, and conventional casting for different palatal vault depths. Material and methodsA total of 30 partially edentulous maxillary casts were custom-made in 15 medium and 15 deep palatal vaults. All stone casts were scanned as reference models in digital files. For the medium palatal vault casts, Co-Cr frameworks of the conventional casting (CON) group (n=5) were fabricated with the lost wax technique. For the 3D printing pattern casting (PPC) group (n=5), wax patterns of the framework were printed, followed by metal casting. The frameworks created for the selective laser melting (SLM) group (n=5) were printed directly by using the SLM machine. The same procedures were followed for the deep palatal vault group. All the metal frameworks were scanned and superimposed with the reference casts by using the Geomagic Control X software program. Discrepancies were measured as mean ±standard deviation (trueness), and the data were statistically analyzed with a 2-way ANOVA test to evaluate the interaction of 2 independent factors (fabrication techniques and palatal vault depths) on a trueness outcome (α=.05). ResultsThe lowest mean ±standard deviation value was 0.092 ±0.023 mm, found from the SLM framework with deep palatal vault group, while the highest value was 0.194 ±0.017 mm, found from the CON framework with deep palatal vault group. Different fabrication techniques interacted with different palatal vault depths in terms of trueness (P<.05); however, no significant differences were observed in the medium palatal vault groups (P>.05). Additionally, color mapping demonstrated the gaps of metal frameworks among the 6 groups. ConclusionsWith the conventional casting technique, the accuracy of the metal framework was affected by the depth of the palate. For medium palatal vaults, all fabricated frameworks had clinically acceptable fit. For deep palatal vaults, the SLM frameworks showed the lowest discrepancy. As a result, the SLM technique is advised for fabricating a better-fitting metal framework for patients with a deep palatal vault.

Monitoring the Morphological Changes of Skeleton-PtCo Electrocatalyst during PEMFC Start-Up/Shut-Down probed by in situ WAXS and SAXS.

Advanced in situ analyses are indispensable for comprehending the catalyst aging mechanisms of Pt-based PEM fuel cell cathode materials, particularly during accelerated stress tests (ASTs). In this study, a combination of in situ small-angle and wide-angle X-ray scattering (SAXS & WAXS) techniques were employed to establish correlations between structural parameters (crystal phase, quantity, and size) of a highly active skeleton-PtCo (sk-PtCo) catalyst and their degradation cycles within the potential range of the start-up/shut-down (SUSD) conditions. Despite the complex case of the sk-PtCo catalyst comprising two distinct fcc alloy phases, our complementary techniques enabled in situ monitoring of structural changes in each crystal phase in detail. Remarkably, the in situ WAXS measurements uncover two primary catalyst aging processes, namely the cobalt depletion (regime I) followed by the crystallite growth via Ostwald ripening and/or particle coalescence (regime II). Additionally, in situ SAXS data reveal a continuous size growth over the AST. The Pt-enriched shell thickening based on the Co depletion within the first 100 SUSD cycles and particle growth induced by additional potential cycles were also collaborated by ex situ STEM-EELS. Overall, our work shows a comprehensive aging model for the sk-PtCo catalyst probed by complementary in situ WAXS and SAXS techniques.

A comparative evaluation of the variations on the shades of pressable ceramic system with the layering technique after different number of firing cycles: An in vitro study.

The main aim of the present study was to compare and evaluate the effect of repetitive firings on different shades of a pressable all ceramic system layered with veneering porcelain. In-vitro comparative study. An in vitro comparative study was conducted, and a total of 60 disc shaped specimens (15 mm in diameter and 0.8 mm in thickness) were made of heat pressed ceramic of shades A2, A3, and B2 (20 discs of each shade) grouped as Group I, II, and III, respectively, using the lost wax technique. The discs were subsequently layered with veneering porcelain followed by glazing and overglazing and underwent a firing cycle at each step until six times combined. CIE L*a*b* measurements were noted on each sample after the third, fourth, fifth, and sixth firing using VITA Easyshade Advance 4.0 spectrophotometer. Statistical Analysis was done by SPSS 17.0 software. One way analysis of variance, multiple comparisons using the Tukey test, and descriptive statistical analysis were done for all the groups in the study. P <0.05 was statistically significant. The mean color differences for the repeated firings were imperceptible (ΔE <1.67) to the human eye for all ceramic samples tested except between the fourth and fifth firing of Group II (shade A3). The analysis revealed that although repeated firings lead to changes in L*, a*, and b* values, the mean color difference was below the clinically acceptable color change (ΔE <3.7).

Evaluation of shear bond strength of feldspathic porcelain on various laser surface treated cobalt-chromium discs

Brief Background The aim of the study is to compare and evaluate shear bond strength of porcelain fused to metal substructure fabricated using conventional method, surface treated with different laser modalities and direct metal laser sintering. Material and Methods Forty samples made of Co-Cr were fabricated, divided into control (Group A) and three test groups (Group B, Group C, Group D) (n=10 each). Groups A, C, D samples were made by conventional lost wax technique and B by laser sintering. All the samples were sandblasted and group C and D were surface treated with Nd: YAG and Er: YAG lasers respectively. Further, samples were veneered using 2mm of porcelain. The samples were placed in a jig and held in a universal testing machine to test the bond strength between Co-Cr and porcelain. Samples were subjected to shear stress until the fracture occurred and the results were noted. Data analysis was done using one- way analysis of variance and Post-Hoc test. Result The mean shear bond strength was highest in group D (Er: YAG laser treated Co-Cr), then group B (Laser sintered Co-Cr), then group A (Sandblasted Co-Cr) and group C (Nd: YAG laser treated Co-Cr) which was the least. Conclusion All the groups showed significant difference in shear bond strength. Er: YAG laser surface treated Co- Cr had highest bond strength to porcelain, then laser sintered Co-Cr, followed by sandblasted Co-Cr and least Nd: YAG surface treated Co- Cr. Key Words Er:YAG Laser, Nd:YAG Laser, Conventional technique, Co-Cr alloy, DMLS, Porcelain, Shear bond strength.

Pysanky to Microfluidics: An Innovative Wax-Based Approach to Low Cost, Rapid Prototyping of Microfluidic Devices.

A wax-based contact printing method to create microfluidic devices is demonstrated. This printing technology demonstrates a new pathway to rapid, cost-effective device prototyping, eliminating the use of expensive micromachining equipment and chemicals. Derived from the traditional Ukrainian Easter egg painting technique called "pysanky" a series of microfluidic devices were created. Pysanky is the use of a heated wax stylus, known as a "kistka", to create micro-sized, intricate designs on the surface of an egg. The proposed technique involves the modification of an x-y-z actuation translation system with a wax extruder tip in junction with Polydimethysiloxane (PDMS) device fabrication techniques. Initial system optimization was performed considering design parameters such as extruder tip size, contact angle, write speed, substrate temperature, and wax temperature. Channels created ranged from 160 to 900 μm wide and 10 to 150 μm high based upon system operating parameters set by the user. To prove the capabilities of this technology, a series of microfluidic mixers were created via the wax technique as well as through traditional photolithography: a spiral mixer, a rainbow mixer, and a linear serial dilutor. A thermo-fluidic computational fluid dynamic (CFD) model was generated as a means of enabling rational tuning, critical to the optimization of systems in both normal and extreme conditions. A comparison between the computational and experimental models yielded a wax height of 57.98 μm and 57.30 μm, respectively, and cross-sectional areas of 11,568 μm2 and 12,951 μm2, respectively, resulting in an error of 1.18% between the heights and 10.76% between the cross-sectional areas. The device's performance was then compared using both qualitative and quantitative measures, considering factors such as device performance, channel uniformity, repeatability, and resolution.

Structure property relations in chitosan based nanocomposite films using WAXS techniques

Structure property relations in chitosan based nanocomposite films using WAXS techniques

A cost-effective and facile technique for realizing fabric based microfluidic channels using beeswax and PVC stencils.

Microfluidic channels fabricated over fabrics or papers have the potential to find substantial application in the next generation of wearable healthcare monitoring systems. The present work focuses on the fabrication procedures that can be used to obtain practically realizable fabric-based microfluidic channels (μFADs) utilizing patterning masks and wax, unlike conventional printing techniques. In this study, comparative analysis was used to differentiate channels obtained using different masking tools for channel patterning as well as different wax materials as hydrophobic barriers. Drawbacks of the conventional tape and candle wax technique were noted and a novel approach was used to create microfluidic channels through a facile and simple masking technique using PVC clear sheets as channel stencils and beeswax as the channel barriers. The resulting fabric based microfluidic channels with varying widths as well as complex microchannel, microwell, and micromixer designs were investigated and a minimum channel width resolution of 500 μm was successfully obtained over cotton based fabrics. Thereafter, the PVC clear sheet-beeswax based microwells were successfully tested to confine various organic and inorganic samples indicating vivid applicability of the technique. Finally, the microwells were used to make a simple and facile colorimetric assay for glucose detection and demonstrated effective detection of glucose levels from 10 mM to 50 mM with significant color variation using potassium iodide as the coloring agent. The above findings clearly suggest the potential of this alternative technique for making low-cost and practically realizable fabric based diagnostic devices (μFADs) in contrast to the other approaches that are currently in use.

The Dimensional Changes of Clasp Arm in Removable Partial Denture Frameworks Fabricated Through DMLS and Conventional Lost Wax Technique: An In Vitro Study

AIM: The aim of the present study is to evaluate the effect of CAD designing on the dimensions of the clasp arm. METHODOLOGY: A Kennedy Class III mod I cast was selected as the reference cast. Samples were divided into 2 groups, Group I with DMLS and Group II with Conventional lost wax technique. Three reference points were selected on the clasp arm and the vertical dimensions were measured in the digital design and compared it with the dimensions at the same points in the final framework. RESULTS: There was slight expansion in group 1 (p-value &gt; 0.05) with mean of -0.035 and standard deviation 0.088. And there was decrease in dimensions in the clasp arm in group 2 (p-value &lt; 0.05) with mean of 0.1741 and standard deviation 0.081. CONCLUSION: From the present study, it was concluded that the dimensions of the clasp arm of DMLS framework increased slightly, whereas the there was significant decrease in the clasp arm dimensions in the framework produced through conventional lost wax technique. Both the frameworks had clinically acceptable fit.

Accuracy of fit for cobaltchromium bar over two implants fabricated with different manufacturing techniques: an in-vitro study

ObjectiveThe purpose of the invitro research was to compare the fit of Cobalt Chromium customized bar fabricated with different manufacturing processes cast metal bar, milled bar and 3D printed bar using scanning electron microscope.Materials and methodsClear epoxy resin molds were prepared. In each mold two parallel implants with a 14 mm distance from each other were embedded. Thirty Co-Cr custom bars were constructed and were divided equally into three groups: Group (I) (Co-Cr conv), group (II) milled bar (Co-Cr milled), and group (III) printed bar (Co-Cr print). The marginal fit at implant-abutment interface was scanned using scanning electron microscope (SEM).ResultsThere was a significant difference between the three studied groups regarding marginal misfit the between implant and fabricated bars with p-value < 0.001. The highest value of micro-gap distance was found in Co-Cr conventional group (7.95 ± 2.21 μm) followed by Co-Cr 3D printed group (4.98 ± 1.73) and the lower value were found in Co-Cr milled (3.22 ± 0.75).ConclusionThe marginal fit of milled, 3D printed and conventional cast for Co-Cr alloy were within the clinically acceptable range of misfit. CAD/CAM milled Co-Cr bar revealed a superior internal fit at the implant-abutment interface. This was followed by selective laser melting (SLM) 3D printed bar and the least fit was shown for customized bar with the conventional lost wax technique.

A Comparison of the Effect of Surface Treatment on Shear Bond Strength of Titanium Alloy

Aim: To comparison the shear bond strength of Titanium alloy with different surface treatment. Materials and methods. cylindrical shaped samples composed of metal and ceramic were prepared by lost wax technique and ceramic buil d up, total 21 samples with different surface treatment, subgroup 7 samples for each group according to surface treatment, each sample was veneered performed by the conventional layering technique according to manufacturers` instruction. A universal testing machine was used to determine the shear bond strength. One- way ANOVA test (analysis of variance) to verify if there any statistical significant difference within each group and among the three groups. Least significant difference (LSD) test to compare between each two groups when ANOVA test showed significant difference. t- test to examine the source of differences. Results. On -way (ANOVA) test was used to analyse the results, there was highly significant differences between the groups. Conclusion. In this study, only treatment of sandblasting offered enough bonding strength, sandblasted with AL2O3 obtained the best results with Tic.

Effect of Different Polishing Systems on Surface Roughness of IPS Empress Ceramic Materials

For evaluation and comparison of the effect of surface treatment (glazings, polishing with rubber wheel and diamond paste, and polishing with rubber wheel) on pressable porcelain (IPS Emax porcelain) surface roughness in comparison with non-treated surface. Forty-disc shaped specimens of baseplate wax with 10 mm diameter and 2 mm thickness have been prepared. They were invested and subjected to lost wax technique in fabricate the pressable ceramic. Following pressing, they have been divided randomly into four groups: Group A: no surface treatments, Group B: glazing (paste, HT, Ivoclar, Vivadent, Germany) glazing (paste, HT, Ivoclar, Vivadent, Germany), Group C: polishing with burs (DIAPRO TWIST, EVE, GmbH, Germany), and Group D: polishing with burs (DIAPRO TWIST, EVE, GmbH, Germany) and diamond paste (All in one, RENFERT, GmbH, Germany). For each specimen, examination of mean roughness profile (Ra) was performed for total surface roughness description. Specimens were stabilized with the acrylic holder used previously in the initial polishing procedure. A contact stylus profilometer was used to conduct a quantitative measurement of surface roughness in micrometers (µm) for all specimens. The highest (Ra) value was for control group (1.9520), whereas the lowest values were in group D (Polishing by rubber wheel .4670. One-way ANOVA test showed a high significant value at (P &lt;. 000), and LSD test showed a high significant value at (P &lt;. 000) when comparison was established among groups. From the results of the current study, we can conclude the following; polishing procedure for the surface of pressable ceramic with or without diamond paste produced better surface smoothness than glazed surface and non-treated surface and polishing with burs could be an alternative to glazing to provide smooth surface.

Effect of different digital technology on the adaptation and retention of Co-Cr partial denture frameworks.

To evaluate the overall adaptation and retention of class I cobalt-chromium (Co-Cr) removable partial denture (RPD) frameworks using three different computer-aided design and computer-aided manufacturing (CAD-CAM) technologies: Indirect wax milling with lost wax technique (LWT), direct milling, and selective laser melting (SLM) technique. An educational maxillary stone model (Kennedy class I) was scanned after preparing rest seats to create a resin model. The resin model was scanned, and the RPD framework was digitally designed and saved as a standard tessellation language (STL) file. Twenty-four Co-Cr RPD frameworks were then constructed and divided into three groups (n = 8) based on fabrication technique: Group A (indirect wax milling with LWT), Group B (direct milling), and Group C (selective laser melting). In Group A, the STL file was used to mill the design from castable resin blanks which were then cast by the LWT. In Group B, the STL file was used to mill the design from the Co-Cr blank directly. Finally in Group C, the STL file was used to print the design from Co-Cr powder using SLM 3D printed technique. Geomagic Control X software was used to measure the overall adaptation of the fabricated RPD frameworks, Retention was also tested using a universal testing machine. One-way Analysis of Variance (ANOVA) test was used to compare the three groups then the Tukey HSD post-hoc test was used for pair-wise comparisons. The significance level was set at p ≤ 0.05. Regarding the overall adaptation, Group B (0.71±0.02mm) showed significantly higher adaptation than Group A (0.96±0.06mm) and Group C (1.05±0.16mm). Regarding retention, Group B (2.03±0.34 N) showed significantly higher retention than Group A (1.00±0.13 N) and Group C (0.78 ±0.17 N). Based on the findings of this in vitro study, Co-Cr RPD frameworks fabricated by direct milling technique revealed the best adaptation and retention.

First evidence for alloying practices in the Chalcolithic Southern Levant (4500–3800 BCE) as revealed by metallography

Excavations at the Chalcolithic site Fazael in the central Jordan Valley uncovered a large number of metal items, many of them polymetallic copper alloys cast in the lost wax technique. Metallography and SEM–EDS analysis on a subset of the assemblage confirm previous notions of the lost wax metallurgy in the Chalcolithic Southern Levant but extend them significantly in three aspects: The Fazael metal assemblage is slightly depleted in its arsenic content compared to metal assemblages from other sites, silt-sized quartz inclusions in unalloyed and polymetallic copper items, and the presence of unalloyed copper inclusions. These latter provide the earliest direct evidence for mixing of different metal types in West Asia, potentially alloying or recycling.

Materials and manufacturing techniques for occlusal splints: A literature review.

To review the materials and fabrications methods of occlusal splints with their advantages and shortcomings and to clarify the indications for each. Temporomandibular joint disorders (TMDs) encompass a range of conditions affecting the masticatory system. Occlusal splints are currently recognized as a viable option for the management of TMDs when they are adopted in conjunction with additional approaches varying from conservative procedures (counseling, biofeedback, physical therapy, pharmacotherapy) to irreversible and less conservative ones (occlusal adjustments, orthodontics, arthroscopy, and surgery). These splints can vary in design, function, and material. The components used to fabricate the splints must withstand occlusal forces, be aesthetically pleasing, comfortable, and minimally interfering with function and phonetics. Traditional methods for fabricating splints include sprinkle-on, thermoforming, and lost wax techniques. However, with the advancement of CAD/CAM technology, additive (3D printing) and subtractive (milling) manufacturing methods expand the range of possibilities by introducing novel solutions for elaborating splints. An electronic search was conducted on PubMed using the following keywords: "occlusal splint", "guard and "materials", and "manufacturing". Thirteen in vitro publications were screened and they consisted of four clinical studies, nine reviews (three of them were systematic reviews), and five case reports. The choice of material is crucial for the success of splint therapy. Factors such as biocompatibility, ease of fabrication, adjustability, cost, and patient preference should be considered. Newer materials and techniques are emerging because of advancements in material science and manufacturing techniques. However, it should be noted that most of the evidence is based on in vitro studies with different methodologies, limiting their validity in daily practice.

AN IN VITRO COMPARISON OF OVERALL FIT OF COBALT-CHROMIUM COPINGS CASTED CONVENTIONALLY FROM INLAY CASTING WAX, PATTERN RESIN &amp; 3D PRINTED RESIN EVALUATED BEFORE &amp; AFTER CERAMIC FIRING CYCLES

Aim: To compare the overall fit of cobalt-chromium copings casted conventionally from inlay casting wax, auto polymerizing pattern resin &amp; 3D printed resin evaluated before &amp; after ceramic firing cycles. Method: A stainless-steel master die assembly was fabricated which was used to fabricate the working models. 60 working dies (Group A Inlay Casting Wax n=20, Group B Pattern Resin n=20, Group C 3D Printed Resin n=20) simulating full crown preparations werestudied. The stainless-steel master die was duplicated using polyvinyl siloxane (PVS) elastomeric impression and poured in gypsum type IV die stone. Dieswere scanned using a digital scanner. 60 cobalt-chromium (Co-Cr) metal copings were fabricated using three different techniques: inlay casting wax, autopolymerising pattern resin&amp; 3D printed resin. Each die was fired with conventional PFM ceramic. A standardized weightwas used to exert uniform pressure on the elastomeric impression material while recording the intaglio surface of the crowns (copings) fabricated before and after ceramic firings. It was thenscanned aiding in STL File. The STL files were later overlapped and evaluated on their respective working die STL file using the software. The overall fit was measured by colour surface mapping software viz before &amp; after ceramic firing cycles. Results: The copings obtained by 3D printed resin technique revealed the best overall fit before and after ceramic firing cycles amongst the three fabrication techniques. Conclusion: 3D printed resin technique had the best overall fit before and after ceramic firing cycles followed by inlay casting wax technique and pattern resin technique.

Decontamination of lithium disilicate ceramics using various photosensitizers, herbal and chemical disinfectants, and the effect of surface conditioners on bond strength values

AimTo assess and compare the antimicrobial efficacy of disinfectants on lithium disilicate ceramic (LDC) used in dental applications and shear bond strength (SBS) of LDC after using different conditioners hydrofluoric acid (HF), self-etching ceramic primers (SECP) and Neodymium-doped yttrium orthovanadate (Nd: YVO4). Materials and methodsOne hundred and twenty LDC discs were fabricated by auto-polymerizing acrylic resin using the lost wax technique. S. aureus, S. mutans, and C. albican were inoculated on thirty discs (n = 30 each). Each group was further divided into three subgroups based on different disinfecting agents used (n = 30) Group 1: Garlic extract, Group 2: Rose Bengal (RB) activated by PDT, and Group 3: Sodium hypochlorite (NaOCl). An assessment of the survival rate of microorganisms was performed. The remaining thirty samples were surface treated using three different LDC surface conditioners (n = 10) Group 1: HF + Silane (S), group 2: SECP, and Group 3: Nd: YVO4 laser+S. SBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40x magnification, The statistical analysis was conducted using one-way ANOVA and Post Hoc Tukey test. ResultsGarlic extract, RB, and 2% NaOCl sample displayed comparable outcomes of antimicrobial potency against C. albicans, S aureus, and S. mutans (p > 0.05). Furthermore, SBS analysis showed HF+S, SECP, and Nd: YVO4+S exhibited comparable outcomes of bond strength (p > 0.05). ConclusionGarlic extract and Rose bengal activated by PDT can be contemplated as alternatives to the chemical agent NaOCl used for LDC disinfection. Similarly, SECP and Nd: YVO4 possess the potential to be used for the surface conditioning of LDC to improve the bond integrity with resin cement.

EFFECT OF REPEATED FIRINGS ON METAL CERAMIC BOND STRENGTH OF CO-CR ALLOY FABRICATED BY DIRECT METAL LASER SINTERING AN IN-VITRO STUDY

Purpose: The bond strength of metal ceramic restorations places a key role for the longevity of the prosthesis which could be affected by the fabrication technique and the number of firings. The current research evaluates the effect of repeated firings on bond strength of metal ceramic systems with copings fabricated from two processing techniques, lost wax technique through induction casting and direct metal laser sintering. Materials and Methods: 21 metal ceramic bars will be fabricated using Direct Metal Laser Sintering (Group DMLS) and 21 using conventional lost wax technique (Group Cast). Each sample will have a dimension of 25x3x0.5mm respectively. In the center of each bar, a 1.1mm thickness of porcelain will be fused onto an 8x3mm rectangular area. Each group is further subdivided into 3 subgroups which are subjected to repeated firings (3, 5, 7) and the bond strength is measured with positioning of the samples on a Universal Testing Machine. Results: Group ANOVA and Post Hoc Tukeys test showed comparison of overall bond strength of ceramic samples fabricated using DMLS &amp; Casting subjected to different Firing was done and the difference in mean was statistically significant (p&lt;0.05). Conclusion: The DMLS group showed slight superior bond strength properties when compared with Cast group.

Bone wax technique for full-endoscopic lumbar laminotomy.

Hemostatic procedures in endoscopic spine surgery have not yet been established, especially in full-endoscopic spine surgery (FESS) performed under continuous irrigation, which has been a major concern for surgeons. Chu et al. had previously reported a technique to convey bone wax during full-endoscopic cervical spine surgery via intracorporeal route by using ball tip of the drill in 2018. However, to the best of our knowledge, there has been no report by surgeons to adopt bone wax as a hemostatic material in full-endoscopic lumbar surgery to date, probably because of difficulty in handling bone wax under continuous irrigation and through a narrow and long working channel in endoscope. We have renewed the bone wax technique (BWT) for hemostasis in FESS, improving its handling by introducing a nozzle applicator, without which the bone wax would stick to the working channel of the endoscope on the way to the bleeding target. This would result in significant loss of bone wax and repeated bone-wax contact would cause dirt build-up on the endoscope lens, which would then be pushed out from the wall of the working channel, thereby disturbing the laminectomy procedure and obfuscating the visual field. Technical details using nozzle-loaded bone wax have been demonstrated.

Effect of pattern materials and fabrication techniques on the color of a pressed lithium disilicate ceramic: An in vitro study

Statement of problemPattern materials and their fabrication techniques have been reported to affect the marginal accuracy and internal fit of pressed lithium disilicate ceramic restorations. However, information regarding their effect on the color of such restorations is lacking. PurposeThe purpose of this in vitro study was to evaluate the color of a pressed lithium disilicate glass-ceramic fabricated from wax or resin patterns by using conventional and milling techniques. Material and methodsFifty-six Ø14×1.5-mm disk pattern specimens were divided into 4 groups based on the pattern material and fabrication technique: conventional wax pattern group (CW), conventional resin pattern group (CR), milled wax pattern group (MW), and milled resin pattern group (MR). Lithium disilicate specimens were fabricated by using the lost wax technique. The CIELab values were measured with a spectrophotometer (VITA Easyshade Advance). The ΔE00 values were calculated and compared with perceptibility (ΔE00=0.8) and acceptability (ΔE00=1.8) thresholds to interpret the color differences. The 2-way ANOVA and Tukey post hoc tests were used to analyze data (α=.05). ResultsTwo-way ANOVA revealed that ΔE00 was significantly affected by the pattern material (P<.001), fabrication technique (P=.034), and their interaction (P<.001). The ΔE00 of the CW group (0.76 ±0.04) was clinically imperceptible. No significant difference in the ΔE00 values was found between the reference and the MW (1.48 ±0.13) and MR (1.51 ±0.15) groups (P=.926), which were both clinically perceptible and acceptable. The highest ΔE00 was that of the CR group (2.06 ±0.22). ConclusionsThe color of the pressed lithium disilicate ceramic was influenced by the wax and resin pattern materials fabricated by using conventional or computer-aided design and computer-aided manufacturing (CAD-CAM) techniques. Only the CW pattern group showed color differences below the clinically perceptible threshold (ΔE00=0.8). The CR pattern group showed the highest color differences, which were not clinically acceptable.