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Dentistry has not been exempt from changes in this era of technology-driven revolution. Entire workflows are already digitalized, and restorations are designed and manufactured using computer-aided solutions. This case report describes the reconstruction of 24 teeth using digital techniques. [ABSTRACT FROM AUTHOR]

The surface roughness constitutes one of the most critical properties of wood and wood veneers for their extended utilization, affecting the bonding ability of the veneers with one another in the manufacturing of wood composites, the finishing, coating and preservation processes, and the appearance and texture of the material surface. In this research work, logs of five significant European hardwood species (oak, chestnut, ash, poplar, cherry) of Balkan origin were sliced into decorative veneers. Their surface roughness was examined by applying a stylus tracing method, on typical wood structure areas of each wood species, as well as around the areas of wood defects (knots, decay, annual rings irregularities, etc.), to compare them and assess the impact of the defects on the surface quality of veneers. The chestnut veneers presented the smoothest surfaces, while ash veneers, despite the higher density, recorded the highest roughness. In most of the cases, the roughness was found to be significantly lower around the defects, compared to the typical structure surfaces, probably due to lower porosity, higher density and the presence of tensile wood. The results reveal that the presence of defects does not affect the roughness of the veneers and increases neither the processing requirements of the veneer sheets before finishing, nor the respective production cost of veneers and the veneer-based wood panels. The high utilization prospects of the examined wood species in veneer production, even those bearing various defects, is highlighted. [ABSTRACT FROM AUTHOR]

In veneer-drying facilities, controllers face many challenges to maintain desired parameters in the final product based on customer's needs. The major challenge is setting process parameters to control the temperature and humidity within the various sections in the drying machine to obtain the desired properties of the final product. The regression tree approach can be used to simplify the complex relationship among process and product variables for identifying critical factors for drying veneer and achieving the desired range of veneer temperature. In this study, we investigated veneer-drying conditions and the short-term effect of climatic variables on veneer temperature. We have shown a three-step process to develop an optimal regression tree for veneer temperature. From the developed optimal tree, we are able to identify the most important threshold points of predictor space and adjustment for the climatic variables on the temperature of veneer sheets. The findings of this study were further investigated in an industrial setting and the desired veneer temperatures were attained for the final product. This application shows that we can follow the path of the optimal tree to pinpoint the most desired veneer temperature outcome. The developed optimal tree is relatively easy to use and interpret to estimate the average response of veneer temperature. [ABSTRACT FROM AUTHOR]

Gingival recession often compromises the esthetics of the patient especially when it occurs in the anterior region . Often the patient exhibits open embrasures, increased crown height, and black triangles. The reduced bone height often compromises the possibility for a predictable outcome after various root coverage procedures. Hence these procedures may not give a satisfactory esthetic results . In addition to that surgical root covege might cause discomfort to the patient and requires considerable healing time. Gingival veneer masks are simple alternative approach in these patients with unsightly gums associated with severe gingival recession especially when they are well motivated for good oral hygiene measures. This article aims to describe a clinical case of a young patient with advanced gingival recession. The gingival prostheses is a boon to patients who are esthetically compromised due to severe gingival recession. [ABSTRACT FROM AUTHOR]

The present work focuses on creating a better understanding of the possibility of forming specific geometric structures from plywood and subsequently develops an improved equation for representing the spring-back phenomenon during the thermoforming process of veneer plywood. Primarily, the formation of multiple bends and their interactions, have been studied with a four-point bending rig. Real-time strains were measured using strain gauges and a kinematic analysis of the macroscopic deformation was carried out through grid strain analysis. It was followed by a geometric conformance study, results of which showed 0.45% deviation from the desired profile angle. Subsequently, a new empirical equation was formulated based on the experimental results using an open-source software, named Eureqa®, to find the change in sector angle after spring-back. The equation was validated by conducting experiments under different conditions and was found to perform well in the forming temperature range of 150–200°C and the pre-forming moisture content range of 20–27.3%. [ABSTRACT FROM AUTHOR]

Blended species plywood blocks comprising of 24 different veneer configurations of naturally durable white cypress pine and non-durable hoop pine were exposed to the subterranean termite Coptotermes acinaciformis in a field trial in Australia. Three thicknesses of cypress (1.8, 2.8, and 3.0 mm) and hoop pine (1.0, 1.5, and 3.0 mm) veneer were included. Blocks were assessed for termite damage using a visual damage rating and mass loss measurement. Blocks using all hoop pine veneers received substantial damage; however, blocks that had cypress face and back veneers had improved termite resistance, particularly for the 1.0-mm hoop pine core veneers. When cypress longbands were blended with hoop pine crossbands that created alternating layers, minimal damage was sustained in the hoop pine veneers; however, the damage increased with increasing hoop pine veneer thickness. All cypress veneers received essentially no termite damage, and cypress veneer thickness did not influence the severity of hoop pine veneer damage. The trial indicated that the plywood made with hoop pine core veneers, cypress pine face, and back veneers offered some termite resistance if the hoop pine veneer thickness was kept thin. Alternating cypress and hoop pine further improved the termite resistance. [ABSTRACT FROM AUTHOR]

Wood-based mass-panels (WBMP) are emerging as an attractive construction product for large-scale residential and commercial construction. Australia is following the lead of Europe and North America with several recent projects being completed using predominately crosslaminated timber panels (CLT). These sawn timber-based panels offer some key advantages to the construction and sawmilling industry. However, veneer-based mass-panel (VBMP) systems could offer additional benefits including the more efficient use of the available forest resources to produce WBMPs that have equivalent to superior performance to CLT. Research to confirm the expected technical viability of veneer-based systems is required. VBMPs could provide a valuable contribution, alongside CLT, to the Australian timber products market. [ABSTRACT FROM AUTHOR]

Copyright of International Journal of Computerized Dentistry is the property of Quintessence Publishing Company Inc. and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

In the present scenario, the people's esthetic requirements and expectations have increased substantially. Hence, the dentists are faced with ever increasing demands to provide their patients with highly esthetic, durable tooth-colored restorations while maintaining a conservative approach to tooth reduction. Over the past 25 years, porcelain veneers can be used for changing the shape or color of the teeth, aligning the teeth, and replacing a pre-existing composite veneer for better esthetics. Patients seek such restorations for a variety of reasons ranging from a minor diastema to a complex malocclusion. Although many patients choose this treatment purely for cosmetic purposes, the dentist should aim at both functional and esthetic purposes. Therefore, dentists should perform a complete examination of the patient before selecting and planning treatment. For optimum results, unaesthetic treatment plan must take into account whether orthodontic movements will enhance the success or stability of the definitive restorations. The combining procedures such as orthodontics and porcelain veneers provide conservative, predictable, esthetic, and functional results. Thus, the aim of this study case was to emphasize the importance of orthodontic treatment in improving esthetic results obtained by porcelain veneers prior to their placement. [ABSTRACT FROM AUTHOR]

The possibilities of using an electrostatic field in the technology for manufacturing plywood by the example of birch veneer with the use of carbamide–formaldehyde epoxy or polyvinyl acetate glues have been considered. It has been shown that preliminary treatment of the glue in an electric field results in a decrease of the glue viscosity and leads to an increase in the plywood strength under chipping, whereas the polarization of plywood samples in the course of the gluing procedure causes the ultimate strength under chipping to increase. The results can be explained as being due to the orientation of the glue macromolecules owing to an electric field, which leads to hardening of the material. This effect may be caused by a double electric layer occurring at the veneer–glue interface, increasing the adhesion of the glue to the veneer, by lowering glue viscosity and improving veneer surface wettability, as well as by an increase in the free surface energy of glues in the course of polarization thereof. [ABSTRACT FROM AUTHOR]

The choice of optimal pressing regime for certain types of substrate is of great importance in production of veneered panels. In this paper, the impact of pressing regime on the bonding strength of beech and oak veneers, glued with urea-formaldehyde (UF) adhesive, on medium-density fiberboard (MDF), and moisture-resistant MDF (MR MDF) substrates was examined. The analyses showed a generally higher bond strength with oak veneer compared to beech veneer, which was also the case with regular MDF compared to moisture-resistant MDF. Multivariate analysis of variance (ANOVA) showed that with beech veneer, all of the used regimes produced better results on regular MDF compared to moisture-resistant MDF. In contrast, with oak veneer, the influence of pressing regime had a more noteworthy impact than the type of substrate used. These results indicated that the use of MR MDF as substrate in combination with UF adhesive was inadequate. [ABSTRACT FROM AUTHOR]

Aim: This study was conducted to evaluate the effect of nanosilia surface coating of pre-sintered zirconia on chipping of veneered zirconia crowns after thermocycling and cyclic loading. Method: Twenty zirconia cores were subjected to nanosilica slurry treatment before sintering then veneered and fired to produce crowns. The crowns ere cemented by resin cement on their epoxy dies and 10 crowns were subjected to 10000 thermocycles and 10000cyclic loading. All crowns were loaded till chipping of veneer layer then the chipped surfaces were examined by SEM/EDX. Results: Crowns which were subjected to thermocycling and cyclic loading gave lower chipping resistance than the non-aged crowns. Conclusions: Treatment of zirconia cores with nanosilica before sintering and after thermal and mechanical aging didn’t increase the chipping resistance of the veneer layer. [ABSTRACT FROM AUTHOR]

Copyright of Quintessenz der Zahntechnik is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Wood Industry / Drvna Industrija is the property of Drvna Industrija and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This case report shows the successful change of a young lady smile, by following standard dental esthetic guide lines. With careful, detailed examination and diagnosis, we could reach our goal toward providing a high esthetic smile change. Patient, dentist and dental technician communication is a must toward the best treatment results. [ABSTRACT FROM AUTHOR]

Purpose: To systematically review clinical studies on prosthodontic complication rates of implant fixed dental prostheses in edentulous patients after an observation period of at least 5 years. Materials and Methods: A literature search was conducted using different electronic databases. Specific terms were used for the database search, which spanned the years 1990 to 2008. The search was augmented by using the option of "related articles" as well as by hand searching of references and relevant journals. Relevant studies were selected according to predetermined inclusion and exclusion criteria. Agreement between reviewers was determined by using Cohen kappa coefficients. Results: The initial database search yielded 8,216 relevant titles. Following the filtering process, 19 studies were finally selected. No study directly compared the incidence of prosthodontic complications of complete implant-supported metal-ceramic versus metal-acrylic resin fixed prostheses in the completely edentulous patient. Studies of metal-ceramic prostheses were scarce and short term. Conclusion: Metal-acrylic resin complete implant fixed prostheses presented with various prosthodontic complications after long-term function. The most frequent complications were veneer fracture and material wear. [ABSTRACT FROM AUTHOR]

Purpose: To assess under load the biomechanical behavior of the cementing system of feldspathic vs alumina porcelain veneers. Materials and Methods: A 3D model of a maxillary central incisor, the periodontal ligament (PDL) and the alveolar bone was generated. Incisors restored with alumina and feldspathic porcelain veneers were compared to a natural sound tooth. Enamel, cementum, cancellous and cortical bone were considered isotropic elastic materials; conversely, dentin was designated as orthotropic. The nonlinear visco-elatic behavior of the PDL was considered. The adhesive layers were modelled using spring elements. A 50-N load at a 60-degree angle to the tooth's longitudinal axis was applied and validated. Stress concentration in the interfacial volumes of the main models was identified and submodelled in a new environment. Results: Regarding tooth structure, strain concentrations were observed in the root dentin below the CEJ. As to the cement layer, tensile stresses concentrated in the palatal margin of the adhesive complex. Conclusion: Despite the effects on tooth deformation, the rigidity of the veneer did not affect the stress distributions in the cement layer or in the adhesive layers. In both cases, the palatal and cervical margins seemed to be the most stressed areas. [ABSTRACT FROM AUTHOR]

Objective: Porcelain veneers have become an interesting treatment option to correct the shape and color of anterior teeth. Because of their limited thickness and high translucency, achieving a good color match is influenced by several variables. The aim of this work was to investigate the influence of natural dentin and resin cement colors on final color match of porcelain veneers. Method and Materials: A preselected shade tab (A1) was chosen as the target color for a maxillary central incisor, and its color parameters (L*a*b*) were measured using a digital spectrophotometer (SpectroShade, MHT). Nine natural dentin colors (Natural Die Material, Ivoclar Vivadent) representing a wide range of tooth colors were used to prepare resin replicas of the maxillary central incisor with a standard preparation for porcelain veneers. The prepared porcelain veneers (IPS Empress Esthetic, A1, 0.6 mm thick, Ivoclar Vivadent) were cemented on the resin dies (nine groups of natural dentin colors) using seven shades of resin cement (Variolink Veneers, Ivoclar Vivadent). The L*a*b* values of the cemented veneers were measured, and ΔE values were calculated against the preselected target color (A1). ΔE greater than 3.3 was considered as a significant color mismatch detectable by the human eye. Results: The seven shades of resin cement had no significant influence on the final color of the veneers, as the measured ΔE values were almost identical for every test group. On the other hand, the color of natural dentin was a significant factor that influenced final color match. None of the 63 tested combinations (nine natural dentin colors and seven resin cement colors) produced an acceptable color match. Conclusion: Thin porcelain veneers cannot mask underlying tooth color even when different shades of resin cement are used. Incorporation of opaque porcelain (high chroma) may improve final color match. [ABSTRACT FROM AUTHOR]

Objective: To investigate the chromatic changes of 3 porcelains after firing on titanium. Method and Materials: Thirty-six veneer crowns were obtained by firing 3 different porcelains to titanium: Ti22 (Noritake), Triceram (Esprident), and Vitatitankeramik (Vita). A single shade was used for each porcelain. Besides the titanium-porcelain specimens, 3 titanium- free controls (one for each porcelain) were obtained. A spectrophotometer was used to measure the color of porcelain facings of the veneer crowns and the porcelain controls. Once the chromatic digital values were recorded, the color differences between the titanium-porcelain samples and the corresponding porcelain controls were computed. The results were statistically analyzed. Results: The least chromatic difference was observed for Ti22 porcelain, and the greatest difference for Triceram porcelain. Regarding the direction of the chromatic alteration after firing on titanium, very significant differences were found between the porcelains. Conclusion: Perceivable differences were found between the shade of the porcelain fired to titanium and that of the same porcelain fired alone. No significant differences were found between the 3 porcelains regarding the total chromatic modification. [ABSTRACT FROM AUTHOR]

A male patient presented for maxillary and mandibular complete-arch prostheses. A total of eight all-ceramic restorations, eight metal-ceramic crowns, and four metal-ceramic fixed partial dentures were placed. The restorations were examined for marginal integrity, anatomic form, surface, and color for a period of 12 months. All restorations were in function at the end of the evaluation period. There was no adverse event. No substantial difference between the all-ceramic onlays and the metal-ceramic crowns was apparent. The all-ceramic restorations exhibited the least plaque growth. Bleeding on probing was minimal at both restoration types. The marginal integrity of the all-ceramic restorations was considered to be nearly as precise as that of the metal-ceramic crowns. [ABSTRACT FROM AUTHOR]

A technique tor manufacturing direct resin composite veneers is presented. Described are the advantages of using an acrylic resin matrix, made before the preparation is begun, to copy anatomic details. An additional step to mask previously prepared dark enamel with opaquers is also described. The advantages and limitations of the procedures are discussed. [ABSTRACT FROM AUTHOR]

Trauma to anterior teeth is relatively common among children and teenagers; it has been estimated that approximately one quarter of the population under the age of 18 years sustain traumatic injury in the form of anterior crown fracture. Reattachment of a fractured fragment to the remaining tooth can provide esthetically pleasing results provided that the fragment is available. In this report, a systematic clinical approach through evaluation of periodontal, endodontic, coronal, and occlusal aspects is presented to help dentists analyze the factors affecting selection of techniques and materials. In addition, use of adhesive materials for tooth fragment reattachment is illustrated. Modifications of the reattachment process, including placement of veneer and radicular post, are also discussed. [ABSTRACT FROM AUTHOR]

Objective: When successive restorative procedures (eg, porcelain veneers, interdental resin composite restorations, and endodontic treatment) are carried out on the same tooth, significant effects on crown flexure can be expected. Method and materials: Dentin-bonded porcelain veneers (experimental group) were assessed in vitro using functional and cyclic thermal loads. They were compared lo natural teeth (control group) with respect to 2 parameters: coronal flexure (investigated using experimental strain gauges) and morphology of the tooth-restoration interface (scanning electron microscopic evaluation). For both veneered and natural teeth, crown deformation was recorded at 5 sequential experimental steps: intact tooth (baseline), Class III cavities, Class III resin composite restorations, endodontic treatment, and endodontic restoration (without posts). Results: No significant differences in crown texture were found between natural and veneered incisors when compared across experimental steps. The main effect for experimental steps was highly significant. When averaged across all specimens (natural and veneered teeth), the endodontic treatment step resulted in the highest crown flexure (1.55x the baseline value).The unrestored Class III cavities and the endodontic restoration were next highest (1.30x and 1.28x the baseline value, respectively). The lowest crown flexures were found after restoration of the Class III cavities (1.13x the baseline value). No measurable microleakage or gaps were detected at the ceramic-resin, resin-enamel, or resin-dentin interfaces (Optibond FL, Kerr). Conclusion: Each subsequent reduction in tooth structure resulted in a substantial increase in crown flexibility, even after restoration Endodontic procedures were responsible for most of the loss in crown stiffness Extensive proximal cutting and restorations seemed to minimally affect crown flexure. Porcelain veneers showed perfect biomimetic behavior, because cumulated restoration procedures had the same effect on natural and veneered incisors. [ABSTRACT FROM AUTHOR]

The article concerns the quality issues in wood industry, and especially the advisability of removing defects from veneers. The research purpose of the study was to analyse the influence of the layered structure of plywood base layer made of low-quality wood on selected mechanical properties of floor composites. The utilitarian purpose is to analyse the possibility of producing floors from low-quality materials reducing waste. Four quality classes of Scots pine veneers (Pinus sylvestris L.) were taken into account: A, B, C, D, from the highest class-A without defects to the lowest class-D characterized by a lot of knots (including broken and falling out ones) and cracks. The base layer of the floors was made of these wood quality classes. The value of the modulus of elasticity in elastic deformation, modulus of elasticity in the dynamic and fatigue tests, stiffness and static bending strength were investigated. The test results showed that, as expected, the samples made of class A had the highest values of the measured parameters (static bending strength, static and dynamic modulus of elasticity, and stiffness). However, the values of the tested parameters for the remaining classes B, C, and D did not significantly differ. It was concluded from the research that the change of the plywood base layer conditions regarding the quality of veneers does not significantly affect the physical and mechanical properties of composites. Hence, it is possible to use wood of lower quality classes for production without verification of which class they belong to, which will significantly reduce the production costs.

Three ⁃dimensional finite elemennt method (3⁃D FEM) is an approach to simulate the intraoral environ⁃ ment by fabricating virtual model in computer software, to provide various options of restorations according to the re⁃ quirements of study, and finally to give relevant mechanic data for clinical reference by stress analysis. 3⁃D FEM has been applied in stomatological research more and more widely in recent years. This review has summarized the applica⁃ tions of 3⁃D FEM in various kinds of dental restorations.

To maximize the value of poplar wood in manufacturing of laminated veneer lumber (LVL), its radial (from pith to bark) and longitudinal (from bottom to top) variations were examined in terms of the density and dynamic modulus of elasticity (ED) of veneer. The veneer sheets were rotary-peeled from seven representative poplar butt bolts (the bottom part of a stem) and seven representative poplar second bolts (the middle part of a stem). A grading strategy for selecting veneer was proposed based on the requirements of LVL products. In this study, the ED value of each poplar veneer sheet was non-destructively measured by the ultrasonic method. The results showed that there was a weak correlation between veneer density and ultrasonic wave velocity. The bolt class (butt or second bolt) did not significantly influence the variation of veneer density and ED. However, the among-bolt variation played a significant role in the variability. A large difference in diameter between two ends of a bolt (i.e. the within-bolt variation) resulted in a low veneer ED. According to the sorting criteria of Chinese Standard “Laminated Veneer Lumber”, the estimated grade yields of the poplar veneer studied were 45.2% for G1, 39.3% for G2, 13.1% for G3, and 2.4% for G4.

In this study, the creep behaviors of composite panels used in library shelves were investigated. For this purpose, two types of wood-composite panels (medium density fiberboard and particleboard), and three types of covering including synthetic laminates, natural veneer, and without cove, and two types of wood joints (fixed and detachable) were used. Dimensions of the book-shelves were in actual shelf size, that is, 1,000 × 300 mm. Totally, 48 shelf specimens were prepared. For the creep test, a 23.5 kg loading level was applied in the center part of the shelves. Measurements on the creep behavior were carried out over 155 days at different intervals. Results indicated that the type of wood-composite as well as the type of veneer had statistically significant effect on the creep behaviors of panels. The lowest creep was observed in MDF panels. Moreover, those panels covered with natural veneer demonstrated significantly lower creep values. The type of joint also had a significant effect on the creeping behavior of the shelves, though not as conspicuous as the type of panels and veneers. Based on the results of the present research project, it is suggested that in order to increase the service life of library shelves it would be better to produce the shelves from MDF panels covered with natural veneers; these shelves should be fixed on supports.

Typically, wood-based composite materials have been developed through empirical studies. In these products, the constituent wood elements have broad spectrums regarding species, size, and anatomical orientation relative to their own dimensions. To define special strength and stiffness properties during a long-term study, two types of corrugated wood composite panels were developed for possible structural utilization. The constitutional elements of the newly developed products included Appalachian hardwood veneer residues (side clippings) and/or rejected low quality, sliced veneer sheets. The proposed primary usage of these veneer-based panels is in applications where the edgewise loading may cause buckling (e.g., web elements of I-joists, shear-wall and composite beam core materials). This paper describes the development of flat and corrugated panels, including furnish preparations and laboratory-scale manufacturing processes as well as the determination of key mechanical properties. According to the results in parallel to grain direction bending, tension and compression strengths exceeded other structural panels’ similar characteristics, while the rigidities were comparable. Based on the research findings, sliced veneer clipping waste can be transformed into structural panels or used as reinforcement elements in beams and sandwich-type products.

Bonded indirect restorations can be difficult to lute in an accurate position due to the lack of preparation geometry. Furthermore, while the use of a rubberdam has been proven to be the best technique for providing the most efficient conditions for adhesive luting, its use often requires the use of secondary clamps, which do not allow the operator to lute more than two prosthetic pieces at the same time. The multi-luting concept is a pragmatic approach that of- fers the possibility to deliver several, if not all restorations, to be bonded at the same time, thus ensuring their correct positioning., (Copyright 2024 SWISS DENTAL JOURNAL SSO 2013; Science and Clinical Topics. License: This work is licensed under a Creative Commons Attribution 4.0 International License.)

Rotary veneers from spotted gum (Corymbia citriodora) and white cypress pine logs (Callitris glaucophylla) recovered from the native forest in Queensland, as well as Queensland plantation hoop pine (Araucaria cunninghamii) logs were used to manufacture LVL products following six different lay-up strategies including blended species LVL. The different lay-up strategies were to determine the opportunities for improving the mechanical performance of plantation softwood LVL by including native forest veneers. The manufactured products were evaluated for their bending performance, tension, bearing strength perpendicular to the grain, and longitudinal-tangential shear strength. The all-spotted gum LVL showed superior performance in all testing compared to other construction strategies. Blending even a small amount of spotted gum veneer with plantation hoop pine veneer resulted in improved mechanical performance, especially in flatwise bending. Opportunities exist to develop more optimised construction strategies that target specific product performances while optimising the use of the variable veneer qualities generated from log processing. [ABSTRACT FROM AUTHOR]

Spindleless lathes have shown great potential for the efficient conversion of small native forest logs in Australia. However, a major impediment to the further commercial adoption of this processing approach for native forest small-diameter logs is the absence of reliable and available data on the quantities of logs possibly available and suitable for this purpose. This study undertaken in hardwood and white cypress pine (Callitris glaucophylla) native forests and at sawmills in Queensland, Australia, demonstrated that there are potentially substantial quantities (up to 10.5 m³ per hectare of Crown native hardwood, 14 m³ per hectare of private forest hardwood and 75,000 m³ per year of Crown white cypress pine) logs suitable for spindleless lathe rotary veneer processing. However, access to and utilization of these logs will depend on many factors including accommodating Government policies and log supply agreements; potential alterations in the code of practice for native forest harvesting, silviculture, tree marking and sales practices; diversion of logs from other uses; and development of appropriate log specifications. [ABSTRACT FROM AUTHOR]

Veneer cutting is a specific machining process, where the chip is the final product. The objective of this article is to investigate on the optimal tool edge geometry, using particle swarm optimization (PSO) algorithm, to obtain the desired veneer thickness. The challenge is to maintain the best quality of veneer product with the control of pre-splitting condition and thickness variation. Numerical results obtained from PSO algorithm are compared and verified with the experimental ones. The proposed model allows us to predict the characteristic tool angles for different chip thicknesses and friction coefficients. For chip thickness range greater than 2 mm, the presplitting condition is no longer satisfied, as in the case of rotary peeling veneer, the need of using pressure bar becomes primordial. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate the effects of framework thickness and cooling rate on the characteristics of fabrication defects in veneer ceramic of bi-layered lithium disilicate glass-ceramic (LDG) and zirconia. Eighty discs of 0.5-mm- and 1.0-mm-thick LDG/zirconia core were manually fabricated and veneered. Samples were divided into 8 groups according to the cooling rate, core material and core thickness, with 10 samples per group. All discs were scanned by micro-CT and 3D-reconstructed. Volume, position and sphericity of each pore defect were measured, and curves were fitted. Pore defect sizes of all samples were algorithm-fitted in two groups: 95% small defects and the rest large defects. Pore defects in veneer in LDG groups were smaller, rounder and farther from the interface with the core (p < 0.01), while large, irregular pores were observed at the zirconia interface. No differences in pore location or sphericity were found between the 0.5-mm- and 1.0-mm-thick samples in the LDG groups (p > 0.01), yet the pores in 1.0-mm-thick veneer in the zirconia core group were smaller, closer to the veneer surface, and rounder than in the 0.5-mm-thick group (p < 0.01). Pore defects in rapidly cooled samples in both LDG and zirconia frameworks were more irregular and closer to the interface with the core (p < 0.01). The pore defects were not only distinguishable between zirconia and LDG groups, but might also be related to their mechanical behaviors. The thickness of the core framework would influence the pore defect location as well as sphericity and was material-relevant. Cooling rate was deemed to be a factor in location and sphericity of pore defects in both LDG and zirconia core frameworks. [ABSTRACT FROM AUTHOR]

The article discusses the challenges facing handlers and dental technicians when carrying out prosthetic reconstruction, especially of the anterior teeth. It notes that patients have high expectations of one individual and aesthetic anterior tooth restoration. It adds how highly aesthetic anterior tooth restoration made of highly translucent zirconium oxide and minimal labial scaffolding gets reduced with a nano-fluorine-apatite glass-ceramic.

Forest Stewardship Council (FSC) represents one of the most common certification schemes in forestry worldwide. The aim of this paper was to highlight the profile of the FSC Chain of Custody (CoC) certified veneer companies from Romania. Data available in January 2019 on the official website of FSC (i.e.www.info.fsc.org) were taken into consideration. Based on the official records, at the beginning of 2019, 43 organizations based in Romania had a FSC CoC certificate for the product category W7 Veneer, most of them being located in the central and western parts of the country. As regards the certification bodies active in Romania, more than half of the valid FSC CoC certificates were issued only by two, namely Soil Association Certification Limited (SA) and SGS Société Générale de Surveillance SA (SGS). By taking into consideration the worldwide demand of certified veneers, it is expected that this sector would gain an increasing attention in the future, meaning that more and more resources should be allocated, including specialized people. [ABSTRACT FROM AUTHOR]

A shortcoming of the laminated bending process is that the product may become distorted after moulding. This study focused on the influence of fibre orientation deviation for individual veneers on the distortion of a moulded shell. The distortion of 90 cross-laminated shells of the same geometrical shape, consisting of seven peeled birch veneers, were studied under relative humidity variation. All the veneers were straight-grained in the longitudinal-tangential plane, but to simulate a deviation in fibre orientation, some of the individual veneers were oriented at an angle of 7° relative to the main orientation of the other veneers in the laminate. A finite element model (FEM) was applied to study the possibility of predicting the results of a practical experiment. The study confirms the well-known fact that deviation in fibre orientation influences shape stability. The results also show how the placement of the abnormal veneer influences the degree of distortion. From this basic knowledge, some improvements in the industrial production were suggested. However, the FE model significantly underestimated the results, according to the empirical experiment, and it did not show full coherence. The survey shows the complexity of modelling the behaviour of laminated veneer products under changing climate conditions and that there is a great need to improve the material and process data to achieve accurate simulations. Examples of such parameters that may lead to distortion are density, annual ring orientation in the cross section of the veneer, the orientation of the loose and tight sides of the veneer, and parameters related to the design of the moulding tool. [ABSTRACT FROM AUTHOR]

Rapid Layer Technology (RLT) uses computer‐aided design/computer‐aided manufacturing (CAD/CAM) to manufacture a veneer layer that is adhesively bonded to the zirconia framework, avoiding firing steps during the fabrication process and thus preventing build‐up of residual stresses. This work studied, using sliding contact fatigue, the in vitro lifetime of restorations produced using RLT compared with restorations produced using conventional veneering techniques. Zirconia copings were veneered with a conventional hand‐layering method (VM9) using a fast (n = 16) or a slow (n = 16) cooling protocol, or with RLT. For the latter, the veneers were CAD/CAM fabricated using a feldspathic reinforced‐glass (Vitablocs Mark II; n = 16) or a polymer‐infiltrated reinforced‐glass network (Enamic; n = 16) and adhesively bonded to the zirconia frameworks. Crowns thus obtained were submitted to sliding contact fatigue against a steatite indenter in a chewing simulator until failure. A Kaplan–Meier survival analysis was conducted. None of the hand‐layered restorations survived after a 2 × 106‐cycle interval, whereas no fractures in the RLT groups were observed. Vitablocs Mark II veneers survived for a longer testing period (3.5 × 106 cycles) than their Enamic counterparts (2.5 × 106 cycles) owing to their superior wear behavior. The RLT represents an efficient method to veneer zirconia frameworks by reducing processing steps and, more importantly, increasing the lifetime of the restorations. [ABSTRACT FROM AUTHOR]

Naturally occurring knots reduce the mechanical strength of wood. Veneers from sugi (Cryptomeria japonica) served as research material to study the effect of knots and holes. Veneer samples were first subjected to a three-point bending test to obtain measured modulus of elasticity (MOE) values. Then, near-infrared (NIR) hyperspectral imaging (HSI) was used to construct a prediction model and map the predicted MOE values. This is the first attempt for MOE prediction from the entire veneer surface based on NIR-HSI technology, while the mathematical part relies on chemometrics and cross-validation partial least squares regression (CV-PLSR). Maps of MOE prediction values could distinguish between latewood (LW) and earlywood (EW), as well as between a sound knot and a dead knot. [ABSTRACT FROM AUTHOR]

Currently there are limited markets in Australia for small-diameter native forest logs. This has resulted in much of this resource being underutilized and regarded as sub-optimal in quality and of low value. This is despite the fact that the wood properties are favorable for a wide range of highvalue products. Traditional processing approaches either have not been able to accommodate small-diameter logs or the resulting product recovery is too low for profitable production. Alternative processing approaches are necessary to enable the efficient recovery of wood from this resource in a form that is usable for high-value product manufacturing. Processing small-diameter spotted gum (Corymbia citriodora) and white cypress pine (Callitris glaucophylla) logs into rotary veneer using new spindleless veneering technology has been demonstrated to yield more acceptable recoveries compared with more traditional sawing approaches. The veneer processing approach was also found to be less impacted by the diameter than sawing, with more consistent recovery rates across the three small-diameter log groups included in this study. The resulting veneer, especially the spotted gum veneer, had visual qualities and mechanical properties well suited to the manufacturing of veneer-based engineered wood products. [ABSTRACT FROM AUTHOR]

It was determined how the impregnation of birch veneers with a mixture of potassium carbonate and urea affected the fire protection properties, shear strength, modulus of elasticity and modulus of rigidity of plywood glued with PF and UF resin. Veneers were impregnated by soaking in aqueous fire retardant solutions with concentrations of 20% and 30%. Measurements of mass loss, burned area and time of ignition showed the fire protection provided to be very effective. Impregnation did not significantly affect the modulus of elasticity or modulus of rigidity of the plywood. Impregnation caused a decrease in bonding quality, especially in the case of plywood with UF resin soaked in water. For the samples with PF resin, both immersed and boiled in water, impregnation had less impact on the shear strength: its values exceeded 1 N/mm2, thus meeting the requirements of EN 314-2. [ABSTRACT FROM AUTHOR]

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The aim of the research presented in this paper is to determine screw withdrawal resistance of composite wood-based panels intended for use in construction. For this purpose, three experimental wood composite panels were made by combining particleboards and constructive peeled veneers of beech, black pine and poplar with thickness of 1,5 and 3,2 mm. The core layer of the composite panels was made of single-layer particleboard with thickness of 16 mm, which was overlaid on both sides with two-ply cross-laminated veneers. Models of composite panels were made by combining a different veneer species for particleboard overlay (beech/black pine, poplar/black pine and poplar/beech). Water-soluble phenol-formaldehyde resin was used for particle bonding and veneering. The results of the research showed that different combinations of veneer species used for particleboard overlay significantly impact screw withdrawal resistance of composite panels. According to the obtained values of screw withdrawal resistance, composite panels can be used in construction. [ABSTRACT FROM AUTHOR]