[Study on the pressure on ceramic veneers during cementation]. / Izuchenie velichiny davleniya na keramicheskie viniry vo vremya ikh tsementirovaniya.

OBJECTIVE: The aim of the study is measuring the magnitude and determining the method of finger pressure exerted by doctors on ceramic veneers during their fixation. MATERIAL AND METHODS: A simulation model was designed in order to measure the volume of finger pressure. Veneers were produced for 2 central incisors. Doctors alternately placed veneers on the model and applied pressure on them for 20 seconds simulating the clinical stage of cementing. The operator recorded the maximum readings of the scales and entered the result on the research protocol. In addition, it was recorded which finger the doctor exerts on the veneer during its cementing to ensure a tight fit: thumb or index finger. RESULTS: The values obtained during cementation of 54% doctors ranged up to 1 kg, 27% of doctors from 1 to 2 kg and only 19% more than 2 kg. 80% of doctors applied the main pressure on the veneer using their thumb, while the pressure force was 1.4 kg. For those doctors who pressed the veneer to the tooth with their index finger, the impact value was 0.8 kg. CONCLUSION: The finger pressure on the veneer during cementation applied by dentists varies, the average pressure on the veneers was about 1.5 kg. The amount of pressure on cement during laboratory tests of cements for fixing veneers differs from clinical values many times. The development of a veneers fixation protocol, taking into account the conducted research, will ensure a reliable and accurate fit of the veneer at the stage of its cementing.

Thickness effect of 2D PdSe2film on performance of PdSe2/Si heterostructure photodetectors.

Two-dimensional (2D) PdSe2film has the characteristics of adjustable bandgap, high carrier mobility, and high stability. Photodetector (PD) based on 2D PdSe2exhibits wide spectral self-driving features, demonstrating enormous potential in the field of optical detection. Here, we design and fabricate PdSe2/Si heterojunction PDs with various thicknesses of the PdSe2films from 10 to 35 nm. Due to the enhancement of light absorption capacity and built-in electric field of heterojunction, the photodetector with thicker PdSe2film can generate more photo-generated carriers and effectively separate them to form a large photocurrent, thus showing more excellent photodetection performance. The responsivity and specific detectivity of the PdSe2/Si PDs with 10 nm, 20 nm, and 35 nm PdSe2films are 2.12 A W-1and 6.72 × 109Jones, 6.17 A W-1and 1.95 × 1010Jones, and 8.02 A W-1and 2.54 × 1010Jones, respectively (808 nm illumination). The PD with 35 nm PdSe2film exhibits better performance than the other two PDs, with the rise/fall times of 15.8µs/138.9µs atf= 1 kHz and the cut-off frequency of 8.6 kHz. Furthermore, we demonstrate that the properties of PdSe2/Si PD array have excellent uniformity and stability at room temperature and shows potential for image sensing in the UV-vis-NIR wavelength range.

Aging rate, environmental risk and production efficiency of the low-density polyethylene (LDPE) films with contrasting thickness in irrigated region.

Physical thickness of low-density polyethylene (LDPE) films might determine the release rate of phthalic acid esters (PAEs) & structural integrity and affect production efficiency. However, this critical issue is still unclear and little reported. Aging effects were evaluated in LDPE films with the thickness of 0.006, 0.008, 0.010 and 0.015 mm in a maize field of irrigation region. The Scanning electron microscope (SEM) results showed that the proportion of damaged area (Dam) to total area of LDPE films was massively lowered with increasing thickness after aging. The highest and lowest Dam was 32.2% and 3.5% in 0.006 and 0.015 mm films respectively. Also, the variations in peak intensity of asymmetric & symmetrical stretching vibrations (ASVI & SSVI) were detected using Fourier transform infrared spectrum (FTIR), indicating that the declines in peak intensity tended to be slower with thickness. Interestingly, the declines in physical integrity were tightly associated with increasing exhalation rate of PAEs. Average releasing rate of PAEs was 38.2%, 31.4%, 31.5% and 19.7% in LDPE films from 0.006 to 0.015 mm respectively. Critically, thicker film mulching can lead to greater soil water storage at plough layer (SWS-PL) and better thermal status, accordingly harvesting higher economic benefit. Therefore, LDPE film thickening may be a solution to reduce environmental risk but improve production efficiency in arid region.

Salivary film thickness and MUC5B levels at various intra-oral surfaces.

OBJECTIVES: In this study, we investigated the salivary film thickness and the MUC5B levels at various intra-oral locations in healthy volunteers, with a focus on the palate. Besides, measurements of the palatal surface area were included to explore the possible relationships between the palatal surface area and the palatal salivary film and MUC5B levels. MATERIALS AND METHODS: The salivary film thickness was determined using filter strips, which were pressed to the mucosal surfaces of five different intra-oral locations; conductance was then analysed using a Periotron. After elution of the strips, the MUC5B levels at various intra-oral locations were determined using ELISA. The palatal surface area was measured using an intra-oral scanner. The surface area was subsequently calculated using the software. RESULTS: The anterior tongue had the thickest salivary film and also the highest levels of MUC5B, while the anterior palate had the thinnest salivary film and lowest MUC5B levels. There was no association between the palatal surface area and the salivary film thickness of the palate. CONCLUSION: The salivary film and MUC5B levels are unequally distributed over the intra-oral regions of the soft tissues. The lack of association between the palatal surface area and the salivary film thickness indicates that a larger surface area is not associated with a relative thinner palatal salivary film. CLINICAL RELEVANCE: The results of the current study increase our understanding of saliva distribution in the oral cavity and could be used as reference values for future studies.

Ultrasonic Interferometric Procedure for Quantifying the Bone-Implant Interface.

The loosening of an artificial joint is a frequent and critical complication in orthopedics and trauma surgery. Due to a lack of accuracy, conventional diagnostic methods such as projection radiography cannot reliably diagnose loosening in its early stages or detect whether it is associated with the formation of a biofilm at the bone-implant interface. In this work, we present a non-invasive ultrasound-based interferometric measurement procedure for quantifying the thickness of the layer between bone and prosthesis as a correlate to loosening. In principle, it also allows for the material characterization of the interface. A well-known analytical model for the superposition of sound waves reflected in a three-layer system was combined with a new method in data processing to be suitable for medical application at the bone-implant interface. By non-linear fitting of the theoretical prediction of the model to the actual shape of the reflected sound waves in the frequency domain, the thickness of the interlayer can be determined and predictions about its physical properties are possible. With respect to determining the layer's thickness, the presented approach was successfully applied to idealized test systems and a bone-implant system in the range of approx. 200 µm to 2 mm. After further optimization and adaptation, as well as further experimental tests, the procedure offers great potential to significantly improve the diagnosis of prosthesis loosening at an early stage and may also be applicable to detecting the formation of a biofilm.

Effect of Noise on Determining Ultrathin-Film Parameters from QCM-D Data with the Viscoelastic Model.

Quartz crystal microbalance with dissipation monitoring (QCM-D) is a well-established technique for studying soft films. It can provide gravimetric as well as nongravimetric information about a film, such as its thickness and mechanical properties. The interpretation of sets of overtone-normalized frequency shifts, ∆f/n, and overtone-normalized shifts in half-bandwidth, ΔΓ/n, provided by QCM-D relies on a model that, in general, contains five independent parameters that are needed to describe film thickness and frequency-dependent viscoelastic properties. Here, we examine how noise inherent in experimental data affects the determination of these parameters. There are certain conditions where noise prevents the reliable determination of film thickness and the loss tangent. On the other hand, we show that there are conditions where it is possible to determine all five parameters. We relate these conditions to the mathematical properties of the model in terms of simple conceptual diagrams that can help users understand the model's behavior. Finally, we present new open source software for QCM-D data analysis written in Python, PyQTM.

Operator versus material influence on film thickness using adhesive resin cement or pre-heated resin composite.

OBJECTIVE: There is a growing interest in using pre-heated composites instead of dual-cured cements when luting indirect restorations. This study evaluated the film thickness obtained from two pre-heated composites and two resin cements, by two different operators. The influence of the materials and the level of expertise of the operator were analyzed. MATERIALS AND METHODS: Forty specimens of human dentin and composite discs were prepared and divided into four groups depending on the luting process. Each group was randomly equally divided to be handled by two operators with different levels of experience. Two of the initial four groups were luted using dual-cured cements and the two remaining groups using light-cured pre-heated composites. Specimen discs were cut after luting, and film thickness was measured using a Digital microscope. Data were analyzed using a 2-way ANOVA with the Holm-Sidak pairwise multiple comparison procedure (p < 0.05). RESULTS: Mean film thickness ranged from 156.16 ± 4.7 to 33.82 ± 0.7 µm. Significant differences (p < 0.001) were noticed between expert and novice results with pre-heated composites. CONCLUSION: Within the limits of this study, using pre-heated composites as a luting cement requires a better level of expertise to achieve a clinically acceptable film thickness. CLINICAL SIGNIFICANCE: Using pre-heated composites as luting agent for indirect restorations requires an experimented skill level to achieve a clinically recommended film thickness.

Zirconia Nanoparticles as Reinforcing Agents for Contemporary Dental Luting Cements: Physicochemical Properties and Shear Bond Strength to Monolithic Zirconia.

Nanofillers in resin materials can improve their mechanical and physicochemical properties. The present work investigated the effects of zirconia nanoparticles (NPs) as fillers in commercial dental luting cements. Two dual-cured self-adhesive composites and one resin modified glass ionomer (RMGI) luting cement were employed. Film thickness (FT), flexural strength (FS), water sorption (Wsp), and shear bond strength (SBS) to monolithic zirconia were evaluated according to ISO 16506:2017 and ISO 9917-2:2017, whereas polymerization progress was evaluated with FTIR. Photopolymerization resulted in double the values of DC%. The addition of 1% wt NPs does not significantly influence polymerization, however, greater amounts do not promote crosslinking. The sorption behavior and the mechanical performance of the composites were not affected, while the film thickness increased in all luting agents, within the acceptable limits. Thermocycling (TC) resulted in a deteriorating effect on all composites. The addition of NPs significantly improved the mechanical properties of the RMGI cement only, without negatively affecting the other cements. Adhesive primer increased the initial SBS significantly, however after TC, its application was only beneficial for RMGI. The MDP containing luting cement showed higher SBS compared to the RMGI and 4-META luting agents. Future commercial adhesives containing zirconia nanoparticles could provide cements with improved mechanical properties.

Evolution Mechanism of Sputtered Film Uniformity with the Erosion Groove Size: Integrated Simulation and Experiment.

In this work, Cu thin films were experimentally fabricated at different target-substrate distances by 2-inch and 4-inch circular planar magnetron targets. Meanwhile, the sputtering deposition of Cu thin films was investigated via an integrated multiscale simulation, where the magnetron sputtering discharge was modeled using the Monte Carlo (MC) method, and the sputtered particle transport was simulated using a coupled Monte Carlo (MC) and molecular dynamics (MD) method. Experimental results indicated that, as the target-substrate distance increased from 30 to 120 mm, the film thickness distribution of the 2-inch target sputtering changed from a bell-shaped curve to a line-shaped curve, while that of the 4-inch target sputtering varied from a saddle-shaped curve to a line-shaped curve. The simulation results were accordant with the experimental results. The simulation results revealed that, at a target-substrate distance of 30 mm, the sputtering particle flow from the 2-inch target overlapped strongly near the substrate center, leading to a bell-shaped film thickness distribution, while the increased diameter of the erosion groove on the 4-inch target reduced the superposition effect of the sputtering particle flow near the substrate center, resulting in a saddle-shaped film thickness distribution. In addition, when the target-substrate distance ranged from 30 to 120 mm, the film thickness uniformity of 4-inch target sputtering was superior to that of 2-inch target sputtering, and the underlying mechanism was discussed in detail.

Thickness Effects on Boron Doping and Electrochemical Properties of Boron-Doped Diamond Film.

As a significant parameter in tuning the structure and performance of the boron-doped diamond (BDD), the thickness was focused on the mediation of the boron doping level and electrochemical properties. BDD films with different thicknesses were deposited on silicon wafers by the hot filament chemical vapor deposition (HFCVD) method. The surface morphology and composition of the BDD films were characterized by SEM and Raman, respectively. It was found that an increase in the BDD film thickness resulted in larger grain size, a reduced grain boundary, and a higher boron doping level. The electrochemical performance of the electrode equipped with the BDD film was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) in potassium ferricyanide. The results revealed that the thicker films exhibited a smaller peak potential difference, a lower charge transfer resistance, and a higher electron transfer rate. It was believed that the BDD film thickness-driven improvements of boron doping and electrochemical properties were mainly due to the columnar growth mode of CVD polycrystalline diamond film, which led to larger grain size and a lower grain boundary density with increasing film thickness.

Investigation and optimization of polarization properties of self-assembled carbon nanotube films.

Super-aligned carbon nanotubes (CNTs) film has strong anisotropy to light propagation. In order to better integrate the self-assembled CNTs into microelectromechanical system (MEMS) for polarization applications, some inherent impacts on polarization properties of CNT film were investigated. We described the polarization effects of the film thickness variation in detail, giving an optimum thickness range which is around 700-800 nm. The amorphous carbon content of CNT film was reduced by oxidation process where the transmittance increased by almost 4 folds. The alignment of CNT arrangement was optimized from 0.41 (Chebyshev orientation parameter) to 0.54 by manipulating the C2H4flow rate from 54 to 80 sccm. More specifically, a sample possessing a degree of polarization up to 99% and transmittance over 45% was obtained through proper regulations. The validated optimization makes the aligned CNT films more feasible and valuable for the integration of the CNT polarimeters with MEMS technology.

Affordable Open-Source Quartz Microbalance Platform for Measuring the Layer Thickness.

The layer thickness measurement process is an indispensable companion of vacuum sputtering and evaporation. Thus, quartz crystal microbalance is a well-known and reliable method for monitoring film thickness. However, most commercial devices use very simple signal processing methods, offering only a readout of the frequency change value and an approximate sputtering rate. Here, we show our concept of instrument, to better control the process parameters and for easy replication. The project uses open-source data and its own ideas, fulfilling all the requirements of a measuring system and contributing to the open-source movement due to the added value and the replacement of obsolete technologies with contemporary ones. The device provides an easy way to expand existing sputtering machines with a proper controller based on our work. The device described in the paper can be easily used in need, being a proven project of a fast, inexpensive, and reliable thin-film thickness monitor.

Film-Thickness Identification Method and Lubrication Characteristic Experiment of Full-Size Water-Lubricated Stern Bearing under Offset Load.

Water-lubricated stern bearing (WSB) is a vital part of the ship propulsion-shaft system, and it is of great significance to monitor and analyze its lubrication status through film thickness data to improve the equipment operational reliability. In this paper, a full-size, large length-to-diameter ratio WSB experiment is carried out, and multi-sectional journal displacement data are collected under offset load. Accordingly, a bearing film-thickness identification model is established, which can identify the dynamic film thickness data in the circumferential direction of bearing section by limited measurement points. On this basis, the film thickness distribution of the full bearing is obtained by combining finite element (FE) simulation and particle swarm optimization (PSO) algorithm. The effect of different speeds on the distributed lubrication characteristics of WSB under offset load was systematically analyzed based on film thickness data. Results show that the maximum identification error of the bearing film-thickness identification model is less than 7%. The bearing lubrication state changes dynamically as the speed increases, and the hydrodynamic lubrication effect in the middle of the bearing is enhanced. The area of each lubrication sub-region varies nonlinearly. Research results are instructive for further determine the service life of the shaft system.

Luting indirect restorations with resin cements versus composite resins: Effects of preheating and ultrasound energy on film thickness.

OBJECTIVE: This study aims to evaluate and compare the film thickness obtained with a resin cement and two composite resins, preheated and/or ultrasonically vibrated, as luting agents. MATERIALS AND METHODS: One hundred and twenty-six (126) pairs of resin discs were randomly assigned to six experimental groups (n = 21) according to luting agent (Variolink Esthetic LC, IPS Empress Direct or Estelite Omega) and cementation technique (preheating at 68°C and/or ultrasonic vibration). Specimens were luted by applying a controlled force. Following sectioning and film thickness measurement through field emission gun scanning electron microscopy, statistical analysis was carried out considering a 5% significance level. RESULTS: Statistically significant lower film thickness was observed in Variolink Esthetic LC group when compared to all composite resin groups (p < 0.001), except IPS Empress Direct preheated and ultrasonically vibrated group (p = 0.073). IPS Empress Direct with ultrasonic vibration yielded statistically lower film thickness values than Estelite Omega groups, regardless of luting technique (p < 0.05). Ultrasonically vibrated Estelite Omega groups showed statistically lower film thickness values than solely preheated groups (p < 0.05). CONCLUSIONS: Both Variolink Esthetic LC and IPS Empress Direct preheated and ultrasonically vibrated provided the lowest film thickness. The addition of ultrasonic vibration during cementation proved to be effective in reducing film thickness of both tested composite resins. CLINICAL SIGNIFICANCE: The cementation technique will have variable results depending on the luting material. Adhesive cementation protocols with composite resins should mainly consider ultrasonic vibration, but also preheating, as strategies for reducing film thickness. The tested resin cement, alongside with IPS Empress Direct composite resin preheated and ultrasonically vibrated, provided the lowest film thickness among the tested materials and techniques.

A practical method for determining film thickness using X-ray absorption spectroscopy in total electron yield mode.

Thin films formed on surfaces have a large impact on the properties of materials and devices. In this study, a method is proposed using X-ray absorption spectroscopy to derive the film thickness of a thin film formed on a substrate using the spectral separation and logarithmic equation, which is a modified version of the formula used in electron spectroscopy. In the equation, the decay length in X-ray absorption spectroscopy is longer than in electron spectroscopy due to a cascade of inelastic scattering of electrons generated in a solid. The modification factor, representing a multiple of the decay length, was experimentally determined using oxidized Si and Cu with films of thickness 19 nm and 39 nm, respectively. The validity of the proposed method was verified, and the results indicated that the method can be used in the analysis of various materials with thin films.

A synergistic interplay between dopant ALD cycles and film thickness on the improvement of the ferroelectricity of uncapped Al:HfO2nanofilms.

The Al:HfO2ferroelectric nanofilms with different total thicknesses and distributions of Al-rich strips are prepared using atomic layer deposition (ALD) in an uncapped configuration. The synergistic interplay between the number of Al-rich layers and the thickness of total film offers the additional flexibility to boost the ferroelectricity of the resulting Al:HfO2nanofilms. By carefully optimizing both the ALD cycles for dopant layer and the total film thickness in the preparation, the HfO2nanofilms in post-deposition annealing can exhibit excellent ferroelectricity. The highest remanent polarization (2Pr) of 51.8µC cm-2is obtained in a 19.4 nm thick Al:HfO2nanofilm at the dopant concentration of 11.1 mol% with a three ALD cycles for Al-rich strips. Remarkable remanent polarization value observed in the uncapped electrode clamping film paves a new way to explore the origin of ferroelectricity in hafnium oxide nanofilms. The observed ferroelectricity of the nanofilm is affected neither by the presence of an interface between the upper electrode and the film nor the choices of the materials of upper electrode in the measurement, ensuring a high flexibility in the designing and fabrication of the relevant devices in the future.

In situ controllable synthesis of Schiff base networks porous polymer coatings for open-tubular capillary electrochromatography.

A uniform Schiff base network (SNW) film was synthesized in situ in a controllable way through continuous flow of reactants inside the capillary. The properties and application of the as-prepared capillary was investigated in capillary electrochromatography. The effects of reaction monomer concentration and reaction time on coating thickness were studied by SEM. The results show that the reaction condition has a significant influence on the morphology and thickness of the SNW films. The thickness of the film can be controlled by changing the concentration of reaction solution and reaction time. Capillaries coated under different conditions were employed to separate four nucleotides by capillary electrochromatography, which demonstrated significant variation of migration time, peak order, and separation efficiency. Analytes containing nitrogen heterocycle structures, such as nucleotides, methylimidazole isomers, and ß-lactam antibiotics, were successfully separated with the prepared open-tubular columns. Under the selected separation conditions, theoretical plate number of four nucleotides is in a range 45,237-104,505 plates·m-1, and the resolutions are 1.98-8.07. A resolution of 1.75 is obtained for methylimidazole isomers. The nucleotides in a real sample, chicken essence seasoning, were determined using the prepared capillary column with satisfactory recoveries in the range 95 to 105%.

The Effect of Texture Floor Profile on the Lubricant Film Thickness in a Textured Hard-On-Soft Bearing With Relevance to Prosthetic Hip Implants.

Polyethylene wear debris limits the longevity of prosthetic hip implants. We design a pattern of axisymmetric texture features to increase hydrodynamic pressure and lubricant film thickness and, thus, reduce solid-on-solid contact, friction, and wear in hard-on-soft prosthetic hip implant bearings. Specifically, we study the effect of the texture floor profile on the lubricant film thickness using a soft elastohydrodynamic lubrication model. We compute the optimum texture parameters that maximize the lubricant film thickness for different texture floor profiles, as a function of bearing operating conditions. Flat texture floor profiles create thicker lubricant films than sloped or curved texture floor profiles for their respective optimum texture design parameters. We find that the texture feature volume is the most important parameter in terms of maximizing the lubricant film thickness, because a linear relationship exists between the texture feature volume with optimum texture parameters and the corresponding optimum lubricant film thickness, independent of the texture floor profile.

The physical properties and anticariogenic effect of experimental resin cement containing ursolic acid.

The aim was to evaluate the physical properties and anti-bacterial activity of resin cement containing ursolic acid (UA) and determine the optimal concentration of UA. Five types of experimental resin cement were prepared according to UA concentration (0, 0.1, 0.5, 1.0, and 2.0 wt%). Flexural strength, film thickness and in vitro cytotoxicity were measured to confirm whether the resin was appropriate under International Organization for Standardization (ISO) criteria. Fifty extracted human molars were prepared, and indirect resin inlays were cemented with experimental resins. Acid-resistant nail varnish was applied, except for the 2-mm area around the restoration. Artificial caries were induced for 6 days through Streptococcus (S.) mutans (ATCC25175). Quantitative light-induced fluorescence (QLF) was used to evaluate the caries progression. One-way analysis of variance (ANOVA) followed by the Dunnett correction were used to statistically analyze the data. In all groups, the physical property of flexural strength, film thickness, and cytotoxicity were satisfied for ISO criteria (p > 0.05). On ∆F (-%) and ∆Q (-%⋅Px) values as QLF parameters, there was a tendency of being lower in groups of resin cement containing higher concentration of UA. Resin cement containing UA of greater than or equal to 0.5% significantly inhibited caries in the area around restoration (p < 0.05). There was no difference between the groups containing UA of greater than or equal to 0.5%. Resin cement containing 0.5% or more UA showed anti-carious effect in the limited range of 2% and satisfied the ISO criteria for flexural strength, film thickness and cytotoxicity.

Microcomputed tomography evaluation of cement film thickness of veneers and crowns made with conventional and 3D printed provisional materials.

OBJECTIVE: To evaluate, through microcomputed tomography (µCT), the cement film thickness of veneers and crowns made with different provisional materials. MATERIAL AND METHODS: A veneer and a crown preparation were performed on a central incisor and a second molar of a dental model, respectively, scanned with an intraoral scanner, and the .stl files were exported to an LCD-based SLA three-dimensional (3D)-Printer. Twenty-four preparations were 3D-printed for each veneer and crown and divided into four groups (n = 6/group): (a) Acrylic resin (Acrílico Marche); (b) Bisacrylic resin (Protemp 4); (c) PMMA computer-aided design and computer-aided manufacturing (CAD-CAM) (Vipiblock); and (d) 3D-printed resin for provisional restorations (Raydent C&B for temporary crown and bridge). Veneers and crowns restorations were performed and cemented with a flowable composite. Each specimen was scanned with a µCT apparatus, files were imported for data analysis, and cement film thickness was quantitatively measured. Data were analyzed by 2-way ANOVA and Tukey post-hoc tests (α = .05). RESULTS: Crowns presented a thicker cementation film than veneers (P < .05).The bisacrylic resin showed the smallest veneer film thickness, similar to the acrylic resin (P = .151), which was not significantly different than the PMMA CAD/CAM material (P = .153). The 3D printed provisional material showed the thicker film, different than all other materials (P < .05). The bisacrylic resin showed a cement film thickness with a high number of voids in its surface. For crowns cementation, the 3D printed provisional material showed the thicker cementation film, different than all other materials (P < .05). CONCLUSIONS: Different provisional materials present different film thicknesses. The 3D printed provisional material showed the highest veneer and crown film thicknesses. Veneers film thicknesses were smaller than crowns for all provisional materials. CLINICAL SIGNIFICANCE: The 3D printed provisional material studied can be satisfactorily used, presenting appropriate adaptation with the tooth preparation, however, it shows the highest cement film thickness for both veneers and crowns cementations when compared with other provisional materials. A better internal fit, or smaller cement film thickness is obtained by CAD/CAM materials, acrylic and bisacrylic resins. Veneer cementation showed a smaller cement film thickness compared with crown cementation for all provisional materials.