Lost-wax Research Articles

Technological Insights into the Evolution of Bronze Bell Metal Casting on the Korean Peninsula

Bronze cast bells have been designed and developed for hundreds of years, with the worldwide spread of several faiths and religions such as Buddhism, Catholicism, and Protestantism. The exceptional ringtones of bronze bell metals have scientific healing and cultural importance. In this review article, we highlight the evolution of bronze bell metal over the decades, its composition, and the complex fabrication technologies used to date. Furthermore, we overview ancient and modern casting alloy technology, especially bronze bell castings in Asia. The bell shape, materials, and alloy casting technology have undergone dramatic change over the years. For comparison, we include different bronze cast bells and their characteristics produced from the Middle Ages to the present times. Based on the data obtained from the bell casting technology surrounding the Korean Peninsula, the major trends in the evolution of bronze bell castings and long-standing traditions of mold materials and alloys are described. In the present review, the effects of different elements on bell materials are qualitatively overviewed, with an assessment of the material and casting properties, service life, and bell sound. We also highlight the challenges of conventional bronze casting and possible solutions for future investment castings and rapid prototyping of bronze bells.

Preliminary clinical effect evaluation of digital head and neck radiotherapy oral positioning stents

Objective: To develop a designing software of digital oral positioning stent for radiotherapy of head and neck, and to compare its clinical effect with traditional oral positioning stents made by lost wax process. Methods: Thirty patients with nasopharyngeal cancer who received oral examination before radiotherapy in the prosthodontics department from July to December, 2021, were selected and divided into three groups according to the patients' wishes, 10 per group: one group without radiotherapy oral positioning stents, one group with traditional oral positioning stents (traditional stents group), and the third group with digital oral positioning stents (digital stents group). Patients' ages range from 20 years old to 71 years old. There were 15 males and 15 females involved in this study. The manufacturing time and comfort of the two positioning stents were evaluated, and the radiation doses of the radiotherapy target areas and surrounding healthy tissues were statistically analyzed at the end of radiotherapy. Results: The manufacturing time of digital stents group [(209±7) min] was much less than that of traditional stents group [(490±10) min] (t=69.85, P<0.001). The comfort of patients' wearing of digital stents [first wearing: 5 (3, 6) score; at the end of radiotherapy: 4 (3, 5) score] was better than that of traditional ones [first wearing: 7 (3, 7) score; at the end of radiotherapy: 7 (3, 7) score] (U=22.00, P=0.033; U=20.50, P=0.023). There was no significant differences in the target radiation doses among the three groups, and the radiation doses of tongue [traditional stents group: (36.74±5.45) Gy; digital stents group: (35.96±4.98) Gy] and mandible [traditional stents group: (35.46±4.19) Gy; digital stents group: (35.34±3.98) Gy] were significantly lower in the patients wearing oral positioning stents than in the patients without oral positioning stents [tongue: (41.49±4.46) Gy; madible: (39.32±3.52) Gy] (P<0.05). Conclusions: Oral positioning stents for nasopharyngeal carcinoma radiotherapy could greatly reduce the exposure doses of tongue and madible of patients. Digital oral positioning stents designed and manufactured by independently developed software had higher production efficiency than the traditional method, and patients' evaluation of comfort was better.

Pioneer Mother

Pioneer Mother

Front and Back Covers, Volume 38, Number 5. October 2022

Front and Back Covers, Volume 38, Number 5. October 2022

Gajnullina Lyajlya Ajdarovna – Senior lecturer at the Department of Altaic Studies and Sinology

This article deals with the study of the cultural influence of Chinese civilization on the cultural developments in the Korean Peninsula in antiquity. Chinese civilization, which originated long before the cultures of neighbouring countries, considerably influenced the formation of the political and social systems and also culture, life, beliefs and everyday life in the countries adjacent to China. Although this topic has received attention several times, however, the specific research interest of the authors is to focus on the influence of Chinese culture on the bronze foundry production of Ancient Korea. In particular, this is the production of funeral bronze mirrors, which were originally used by both the Chinese and ancient Koreans for religious and cult purposes. The authors have traced the direct influence of the Chinese bronze casting technique on the development of bronze casting art in the ancient Korean proto-states. This indicates an obvious cultural influence of the neighbouring civilization. The authors used items from the museums of the Republic of Korea, Russia and Japan.

Marginal Misfit of 3D-Printed (Selective Laser Sintered), CAD-CAM and Lost Wax Technique Cobalt Chromium Copings with Shoulder and Chamfer Finish Lines: An In-Vitro Study.

Background and Objectives: The aim was to compare the Misfit of 3D-Printed, Selective laser melting (SLM), milled (Computer aided design-Computer aided manufacture CAD-CAM) and Lost wax technique (LWT) fabricated Cobalt chromium (CoCr) alloy copings on shoulder (SH), radial shoulder (R-SH) and chamfer (CH) finish line configuration. Materials and Methods: Ninety resin, second maxillary premolar teeth were prepared for metal-ceramic crowns, equally divided into (n = 30) SH, R-SH and CH margin preparations. For each preparation design (SH, R-SH and CH), CoCr copings were prepared using SLM, CAD-CAM and LWT. This resulted in nine study groups with 10 CoCr copings each. The marginal misfit of specimens was assessed with a high-resolution digital microscope. Misfit was evaluated in vertical and horizontal dimensions in μm. Data were analyzed using ANOVA and a post hoc multiple comparisons test. Results: For vertical misfit, the highest was observed in SLM samples with chamfer margin (167.96 ± 24.1), and the least was shown by CAD-CAM samples with radial shoulder (58.8 ± 12.53). CAD-CAM and shoulder margins showed the least vertical misfit. For horizontal misfit, the maximum was observed in SLM samples with shoulder margin (137.94 ± 37.85) and the least by LWT samples with chamfer (89.38 ± 14.81). Chamfer margins and LWT samples showed the least horizontal misfit among the group samples. Fabrication technique and finish line design play a critical role in reducing the marginal misfit of CoCr copings. Conclusions: For vertical misfit, SLM copings showed poor outcomes compared to CAD-CAM specimens, however comparable outcomes to Cast specimens. SLM copings showed comparable horizontal misfit outcomes to CAD-CAM specimens and low misfit compared to Cast copings, respectively. Vertical misfit was low with shoulder margins, and horizontal misfit was better with chamfer marginal configuration.

Marginal and Internal Gap of Metal Copings Fabricated Using Three Types of Resin Patterns with Subtractive and Additive Technology: An In Vitro Comparison.

This study analyzes the evidence of the marginal discrepancy and internal adaptation of copings fabricated using three types of resin patterns with subtractive (milling) and additive technology (3D printing), as it is not widely reported. Working casts (n = 15) were scanned and patterns were completed using computer-aided designing (CAD). Resin patterns were fabricated using the designed data and divided into three groups according to the method of fabrication of patterns: subtractive technology–CAD milled polymethyl methacrylate resin (Group-PMMA), additive technology [digital light processing (DLP) technique]–acrylonitrile–butadiene–styrene (ABS) patterns (Group-ABS), and polylactic acid (PLA) patterns (Group-PLA). Resin patterns were casted with Cobalt–Chromium (Co–Cr) alloy (lost wax technique). Internal and marginal gaps of the metal copings were analyzed with the replica technique under optical microscope. The Kruskal–Wallis test was used to compare values among the groups, and post hoc multiple tests confirmed the specific differences within the groups. The median marginal gap was least for CAD milled resin patterns, followed by PLA printed resin patterns and ABS printed resin patterns. There were significant differences between Group-PMMA and Group-PLA and Group-ABS (p = 0.0001). There was no significant difference between Group-PLA and Group-ABS (p = 0.899). The median internal gap was least for metal copings fabricated from Group-PLA, followed by Group-ABS and Group-PMMA. The differences were not statistically significant (p = 0.638) for the internal gap. Full metal Co–Cr copings fabricated from the milled PMMA group had a better marginal fit, followed by the PLA and ABS printed groups. Copings fabricated with the PLA printed group had the best internal fit, though the values were statistically insignificant between the groups.

Objects of the Funerary Cult in the Han Dynasty. Gold and Silver Items. Aesthetics of Gold and Silver in the Han Dynasty

The unification of China under the rule of the Han Dynasty and the subsequent prosperity of the state inevitably led to a sharp increase in the production of gold and silver items. The emperors of the Western Han Dynasty often rewarded officials who had served with gold to the extent that cast gold discs and gold bars were included in circulation. Looking at the gold and silver items that archaeologists find in the tombs of the Han period makes one see the superiority of utensils in this era over the items of previous periods both in quantity and in their typology, and possibly in terms of manufacturing complexity. Having become an independent craft, separate from traditional bronze casting, it strongly influenced the art of subsequent Chinese dynasties. Gilding technologies appeared in China as early as the early Zhanguo period. This highly commendable art used in the decoration of bronze, which was densely covered with gold, reached its maturity in the pre-Qin period and gained popularity during the Han Dynasty. Most importantly, in the Han Dynasty, the fine art of decorating with silver and gold reached a new, higher level and, no longer being part of the bronze casting craft, received independent development. Silver utensils of the Han period are found evenly throughout the territory of modern China. Silver caskets, funnel-shaped vessels and many ornaments were found in the tombs of the Jing king, Liu Sheng, in Zhongshan, the Huai king, Liu Xiu, and the Mu king, Liu Chan, in the same city district. Gold and silver vessels are evidence of the development of the art of working with gold and silver. Silver and gold vessels that archaeologists find in the graves of the highest tribal nobility of the Han Dynasty not only speak of the high level of this industry in the Han Dynasty but also testify to a unique culture and help us better understand the society of this time.

Memorial landscapes, recognition, and marginalisation: a critical assessment of Adelaide's ‘cultural heart’

Memorial landscapes are powerfully instructive. Cast in bronze or carved in stone, memorials speak to us of who and what we should admire and those characteristics we should aspire to emulate. As such, memorial landscapes are texts. However, memorial landscapes are equally about remembering and forgetting. Drawing upon a critical examination of the memorial landscape of Adelaide’s cultural precinct this paper examines ongoing silences regarding Indigenous pre-history, the processes and impacts of British colonisation, and how these are remembered and/or silenced within this place. Framed by post-colonial literature, this paper reveals that notwithstanding movements towards reconciliation in Australia, Adelaide’s cultural precinct firmly remains a settler landscape. Those few memorials raised to or acknowledging Indigenous people are pushed to the margins, poorly maintained, or framed through service to the Empire.

Evaluation of the Accuracy and Adaptation of BioHPP Removable Partial Denture Frameworks Constructed by Milling vs the Pressing Technique.

To evaluate the accuracy and adaptation of BioHPP removable partial denture frameworks constructed from milling vs the pressing technique. This in vitro study was applied on an educational maxillary stone model with bilateral bounded saddles. Two different manufacturing techniques were used, and thus two groups were defined: (1) the pressed group, in which 20 BioHPP frameworks were constructed by milling a castable resin that was pressed into BioHPP using the lost wax technique; and (2) the milled group, in which 20 BioHPP frameworks were constructed directly by milling the BioHPP blanks. The accuracy of the frameworks was evaluated using Geomagic Control X software, and the gap distance was captured using a stereomicroscope. The milled group showed higher values of accuracy than the pressed group in the x, y, and z axes, and according to Student t test, this difference was statistically significant in the x and z axes. Regarding the adaptation of the frameworks, the milled group showed lower adaptation values than the pressed group. Student t test showed that this difference was statistically significant regarding adaptation of the major connector. However, there was no statistically significant difference concerning adaptation of the denture bases between the two groups. Within the limitations of this study, it could be concluded that: (1) the milling technique could be used to fabricate BioHPP RPD frameworks with higher accuracy than the pressing technique; and (2) the pressing technique showed less gap distance (ie, better adaptation) at the area of the major connector.

ACCURACY OF REMOVABLE PARTIAL DENTURE METAL FRAMEWORKS FABRICATED BY COMPUTER-AIDED DESIGN/ COMPUTER-AIDED MANUFACTURING METHOD: A SYSTEMATIC REVIEW AND META-ANALYSIS.

This systematic review and meta-analysis aimed to investigate the accuracy of removable partial denture (RPD) frameworks fabricated by computer-aided design/ computer-aided manufacturing (CAD/CAM) systems compared to frameworks produced by conventional casting methods. A systematic literature search was conducted in electronic databases following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, using formulated Boolean operator for searching articles evaluating the fit accuracy of CAD/CAM-fabricated RPD metal frameworks. The agreement of data collection among the reviewers was confirmed using the Cohen kappa coefficient. The modified methodological index for non-randomized studies (MINORS) scale was used to assess the quality of the included studies. Heterogeneity among studies was evaluated, and meta-analyses with global and subgroup analyses were performed. A total of 208 articles were identified with 18 articles available for the narrative review and 7 studies available for meta-analysis on the 3D-printed frameworks for RPD (the overall Cohen kappa coefficient = 0.944). There was no article on the accuracy of RPD frameworks made by milling method. The meta-analysis revealed that the misfit of frameworks obtained with the CAD/CAM method was significantly higher than that of the conventional lost wax and casting method (SMD = 1.23 μm, 95% CI = 0.3610-2.0981 μm, z = 2.77, P = .0055). Regarding the CAD/CAM techniques used for fabricating RPD metal frameworks, the within subgroup analysis showed that the CAD/CAM-based indirect fabrication method produced frameworks with fit accuracy more similar to the conventional lost-wax and casting method (SMD = 1.15 μm, 95% CI = - 0.06136-2.9192 μm, z = 1.28, P < .01) than the CAD/CAM-based direct fabrication method (SMD = 1.35 μm, 95% CI = -0.2722-2.4381 μm, z = 2.45, P < .01), even though there was no statistical difference between the techniques (P = .8482). The fit accuracy of RPD metal frameworks fabricated by the CAD/CAM method was lower than that of frameworks fabricated by the conventional casting method, but it was within the clinically acceptable range in dimensional misfit. The indirect metal 3D printing technique based on pattern printing and subsequent casting produced frameworks with fit accuracy more similar to the conventional method than the direct fabrication technique.

METALWORKING AT MAYAPAN, YUCATAN, MEXICO: DISCOVERIES FROM THE R-183 GROUP

AbstractThis article presents a compositional analysis of metal artifacts from the Postclassic period (a.d. 1100–1450) city of Mayapan, Yucatan, Mexico. We document metallurgical production at R-183, an elite residential group and one of the most significant archaeological contexts associated with metalworking at Mayapan. Salvage excavations in 1998 recovered a small cache containing 282 copper bells, two miniature ceramic vessels filled with metal, and production debris including loose casting sprues and miscast bells. Metallographic analysis of a small copper bell and wire fragments from the cache reveals lost-wax casting production techniques. X-ray fluorescence spectrometry (XRF) of metal artifacts provides insight into the range of metals used by the R-183 metalworkers, which included copper-lead, copper-tin, and copper-arsenic alloys, and how these alloys compare to assemblages recovered from other contexts at the city. Our findings strongly suggest the use of remelting and casting techniques, likely utilizing remelted metals of both West and central Mexican origin, together with the use of imported goods made from a range of copper alloys.

Погребение среднесарматской культуры курганного могильника Песчаный IV: результаты сравнительно-типологического, радиоуглеродного и изотопного исследований

The paper addresses the results of the study of a rich Middle Sarmatian female burial (end of the 1st century BC — first half of the 1st century AD) discovered in the Sal-Manych steppe, on the border between the Rostov Oblast and Kalmykia. The funerary rite and goods are typical for elite burials of the Middle Sarmatian culture (diagonal burial in a large rectangular pit with a recess, two cast bronze cauldrons, clothes with golden elements, imported fibulae, a gem). The authors have conducted the comparative and typological analysis of chronological indicators found among the grave goods, as well as radiocarbon dating, which allowed to narrow down the chronological interval for the burial. Study of strontium (87Sr/86Sr) isotopes ratio from the buried woman’s dental enamel and background samples from the studied region have showed that the Sarmatian woman buried in the Peschany IV barrow group was of local origin. The interdisciplinary approach allowed to reconstruct the life story of the buried woman and her grave goods.

Fracture of Lithia Disilicate Ceramics under Different Environmental Conditions.

The objective of this research was to quantify the effect of surface degradation and abrasion separately and in combination on the flexural strength of lithia disilicate ceramics. Lithia disilicate disks were fabricated using the lost wax technique and pressing in vacuum. The eight groups in this pilot experiment were (i) reference, hydrated in distilled water for 24 h prior to fracture; (ii) reference, non-hydrated group; (iii) 28-day pH cycling group; (iv) 125K chewing cycle group; (v) combined pH cycling + 125K chewing cycle; (vi) constant pH 2 solution for 28 days; (vii) constant pH 7 solution for 28 days; and (viii) constant pH 10 solution for 28 days. pH cycling is a method that alternates between pH 2, 7 and 10 over 28 days. A total of 15 disks were used for each group. All the groups were tested using the biaxial piston and a three-ball flexural strength test to obtain their biaxial flexural strength. pH 2 constant immersion demonstrated the highest fracture strength and was significantly greater than all other groups (p < 0.0001). Chewing and pH cycling + chewing groups exhibited the lowest fracture strengths and were significantly lower than all other groups (p < 0.0001). The damage observed from the chewing simulator does not represent apparent clinical fractures.

Publisher Correction to: Characterization of the as-cast microstructure and selected properties of the X-40 Co-based superalloy produced via lost-wax casting

Publisher Correction to: Characterization of the as-cast microstructure and selected properties of the X-40 Co-based superalloy produced via lost-wax casting

Comparison of the Marginal and Internal Discrepancy of Metal-Ceramic Restorations Produced by Milling for Soft Metal, Direct Metal Laser Sintering and Casting Methods: An In Vitro Study

Aim: To evaluate the effect of ceramic firing cycles on the internal and marginal discrepancy of restorations fabricated using conventional lost wax casting (LW), direct metal laser sintering (DMLS), and milling for soft metal (MS). Materials and Methods: A total of 45 restorations were produced by LW, DMLS, and MS methods ( n = 15), according to the digital impression on the metal die representing the prepared first molar. The internal discrepancy (ID) was measured through the silicon weight method and the marginal discrepancy (MD) was measured using a light microscope. ID and MD measurements were repeated following the metal manufacturing, ceramic application, and glazing. Statistical analyses were conducted by means of two-way analysis of variance and Tukey-HSD ( α = 0.05) tests. Results: Statistically significant differences were found between the fabrication methods ( P ≤ 0.001) both for MD and ID. The mean MD values of the restorations were 31.4 ± 13.8 µm for MS, 20.8 ± 14.4 µm for LW, and 7.3 ± 6 µm for DMLS. A statistically significant increase was observed in the mean MD values of metal frameworks ( P ≤ 0.001) following ceramic and glaze applications. However, no statistically significant difference was found between the ceramic and the glaze applied stages ( P = .072). The mean ID values were 37 ± 5.7 mg for LW, 28 ± 6.1 mg for DMLS, and 21.6 ± 7.3 mg for MS. Unlike the manufacturing method, ceramic firing cycles had no effects on the ID ( P &gt; 0.05). Conclusion: MS had the highest mean MD, but it had the lowest ID. The ceramic firing had a significantly negative effect only on MD.

Rehabilitation of lateral maxillary defect with intact ridge using obturator with hollow bulb extension technique

Acquired defects in the maxilla lead to oro-antral communication with the nasopharyngeal complex. In recent times, post-Covid necrosis of maxilla due to mucormycosis leads to rapid invasion of surrounding tissues resulting in a maxillofacial defect. The surgically resected maxilla can have a devastating impact on the lifestyle, esthetics, speech and function of the patient. Obturators provide a hollow extension into the defect that seals the oro-antral defect and stops any communication between oral cavity and nasal complex. This case report describes the prosthodontic rehabilitation of a maxillary defect involving the left lateral hard palate and left posterior buccal mucosa with intact ridge over the defect area using a hollow bulb obturator. The lost wax technique used for fabrication of the obturator is an easy, cost-effective technique which is simple to execute from available resources. It provides hollowness to the prosthesis and reduces weight of the prosthesis thereby aiding in retention and stability of the denture.

Cast bronze vessels in the northern Adriatic region (c. 600 AD).

&#x0D; &#x0D; &#x0D; Although cast bronze vessels of the 6th–8th centuries are not recorded in particularly large numbers, their production and distribution provide a representative sample of the general economic trends and of the evolution of trade networks in the post-Roman Mediterranean.&#x0D; The geographical dissemination of these objects shows that at the turn of the 6th century, the northern Adriatic region became the main gateway of ‘eastern-style’ vessels into Central Europe and the Western Mediterranean. The region was thus replacing the Rome area as the main Western hub for redistributing this type of object. From the northern Adriatic area, several types of vessels were distributed both over land along the Po and Rhine valleys and through maritime routes connecting the Adriatic with Carthage and the Spanish Levant.&#x0D; The intrinsic features and the depositional contexts of the post-Roman cast bronze vessels suggest that they were manufactured according to different quality standards, which targeted different social milieus. Furthermore, mapping the distribution of the different quality standards reveals that each of them might have been distributed by different networks of merchants and unveils the impact of transportation costs on the final price of these products.&#x0D; &#x0D; &#x0D;

Metalworking in Bronze Age China: The Lost-Wax Process by Peng Peng (review).

Metalworking in Bronze Age China: The Lost-Wax Process by Peng Peng (review).

Three-dimensionally (3D) printed sand molds for custom glass parts

The presented research investigates a digital fabrication method for custom glass building elements based on three-dimensionally (3D) printed molds. Custom glass parts with specific geometries usually require several steps of manufacturing, highly specialized craft, or machinery. Computer Numerical Control milled steel molds are only suitable for large lot sizes due to their high cost and limited geometric freedom. Lost-wax casting requires several steps of manufacturing and post-processing. This paper investigates an accessible, low-cost process for shaping glass artifacts using 3D-printed molds to close the gap between mass-produced and custom-crafted glass elements. Previous research has demonstrated the potential of using binder jetting with inorganic binders for glass casting. This paper investigates a range of traditional manufacturing methods besides glass casting that can be combined with 3D-printed molds, including foundry and kiln casting, blow molding, and slumping. The aim is to extend the manufacturing possibilities and provide a range of approaches for three-dimensional glass. The goal is to simplify the process from design to production of three-dimensional solid, hollow, or doubly curved sheet glass elements with high precision. This paper presents investigations of binder jetting techniques and material considerations, their heat resistance, compatibility with different glass- making processes, and coatings for mold treatment. Furthermore, the precision of the resulting glass parts is evaluated, and design guidelines for glass typologies are defined. Glass bricks or sheets for facades with geometric features enabled by the presented fabrication method could allow for novel optical, structural, or decorative properties in building elements.