Tooth Model Research Articles

Students' and tutors' perceptions of a deliberate simulated practice using patient-specific virtual and three-dimensional printed teeth models: A pilot study.

This pilot study aimed to investigate the perceptions of dental students and their tutors of a deliberate simulated practice using patient-specific virtual and three-dimensional (3D) printed teeth models. This is before they perform their first indirect posterior tooth restoration on their patients. Seventy-eight fourth-year dental students from the 2021 Comprehensive Clinic I course at the University of the Andes, Chile, were invited to participate in a deliberate practice protocol. This consisted of digitally scanning their patients' teeth, printing the files three-dimensionally, and loading them into a virtual reality (VR) dental simulator to create patient-specific models. Subsequently, they practiced the same indirect posterior restorations on these models before performing them on their actual patients. Perceptions about students' preparedness to perform tooth preparations before and after the protocol were collected from students and their tutors through surveys. Sixty-three students (43 female) and six clinical tutors (all male) participated in the study. Before practicing with their patient-specific models, most students believed they had the knowledge, practical skills, and self-confidence to perform indirect restorations on their patients. However, after the protocol, most students thought their self-confidence increased and felt better prepared to treat their patients. Most students preferred the 3D-printed models over the VR models to practice but mentioned that it did not feel like drilling dental enamel. Tutors believed that participating students had higher self-confidence when treating their patients and were more autonomous. This study demonstrated that students and clinical tutors had positive perceptions of practicing with patient-specific virtual and 3D-printed teeth models before students performed their first indirect restorations on their patients.

New technique for detecting cracked teeth and evaluating the crack depth by contrast-enhanced cone beam computed tomography: an in vitro study

BackgroundCracked teeth may cause various clinical symptoms depending on the extension depth of the crack and the subsequent bacterial infections. However, techniques to reliably determine the extension depths of cracks in teeth before treatment are lacking. The aim of this study was to develop a new technique based on contrast-enhanced cone beam computed tomography (CBCT) to improve the accuracy of crack depth evaluation in vitro.MethodsWe developed an in vitro artificial simulation model of cracked teeth. Pre-experimental CBCT (pre-CBCT), and micro-computed tomography (micro-CT) were first performed for all cracked teeth (n = 31). Contrast-enhanced CBCT was then performed by infiltrating the crack with ioversol under vacuum conditions. The sensitivities of pre-CBCT and contrast-enhanced CBCT for the diagnosis of cracked teeth were calculated. According to the K-means clusters, crack depths measured by micro-CT were changed into categorical variables. Bland–Altman plot and the intraclass correlation coefficient (ICC) were used to analyze the consistency of the crack depths between the pre-CBCT and contrast-enhanced CBCT, as well as the ICC between the contrast-enhanced CBCT and micro-CT. Receiver operating characteristic (ROC) curves were generated to assess the ability for predicting crack depth in the differential diagnosis using pre-CBCT and contrast-enhanced CBCT. Restricted cubic splines were also used to model the non-linear relationship between the crack depths of contrast-enhanced CBCT and micro-CT.ResultsThe sensitivities of pre-CBCT and contrast-enhanced CBCT were 48.4%, and 67.7%, respectively. The ICC value of crack depth as measured by pre-CBCT and contrast-enhanced CBCT was 0.847 (95% confidence interval [CI] 0.380–0.960; P < 0.001). The areas under ROC curves (AUC) of pre-CBCT and contrast-enhanced CBCT were different: the AUC of pre-CBCT was 0.958 (P = 0.000, 95% CI 0.843–1.074), and the AUC of contrast-enhanced CBCT was 0.979 (P = 0.000, 95% CI 0.921–1.037), and the difference was not statistically significant (Z = − 0.707, P = 0.480). The ICC value of crack depth as measured by contrast-enhanced CBCT and micro-CT was 0.753 (95% CI 0.248–0.911; P < 0.001).ConclusionContrast-enhanced CBCT under vacuum conditions with a contrast medium can significantly improve the crack detection rate of cracked teeth; however, it cannot measure the crack depths accurately.

Dense representative tooth landmark/axis detection network on 3D model

Artificial intelligence (AI) technology is increasingly used for digital orthodontics, but one of the challenges is to automatically and accurately detect tooth landmarks and axes. While many attempts have been made to streamline the orthodontic treatments by automatic technologies, the detection of the tooth landmarks and axes is still left to experienced dental practitioners and performed manually. This is partly because of sophisticated geometric definitions of them, and partly due to large variations among individual tooth and across different types of tooth. As such, we propose a deep learning approach with a labeled dataset by professional dentists to the tooth landmark/axis detection on tooth model that are crucial for orthodontic treatments. Our method can extract not only tooth landmarks in the form of points (e.g. cusps), but also axes that measure the tooth angulation and inclination. The proposed network takes as input a 3D tooth model and predicts various types of the tooth landmarks and axes. Specifically, we encode the landmarks and axes as dense fields defined on the surface of the tooth model. This design choice and a set of added components make the proposed network more suitable for extracting sparse landmarks from a given 3D tooth model. Extensive evaluation of the proposed method was conducted on a set of dental models prepared by experienced dentists. Results show that our method can produce tooth landmarks with high accuracy. Our method was examined and justified via comparison with the state-of-the-art methods as well as the ablation studies.

Evaluation method for tooth wear of roller bits based on the fractal dimension of the rock surface

During drilling operations, the drill bit is worn out while breaking the rock. The roller bit is an important rock-breaking tool, but our research on its wear mechanism is still inadequate. Therefore, in response to this problem, this paper establishes a fractal characterization method for surface roughness based on the morphological features of the rock and bit surface. Combining the worn bit surface morphology and energy spectrum analysis results, it is determined that the wear mechanism of roller bit teeth is mainly abrasive wear, fatigue wear and adhesive wear, which are mainly squeezing and spalling. The rock is broken by roller bit under the action of drilling pressure and tangential force, so the contact force model of the single tooth pressed into the rock is established, and the reacting force of the rock on the bit tooth is deduced based on the rock crush conditions. According to the rolling friction characteristics of roller cone bits, the friction coefficient in rolling conditions is calculated. Then, according to the wear mechanism of the cone bit, the actual contact force and real contact area between the cone bit and rock at the bottom of the hole, a roller bit teeth wear equation is established, consisting of rock properties, bit properties and working condition parameters. The bit parameters and drilling parameters are regarded as controllable parameters, and the rock properties are regarded as uncontrollable parameters. In order to highlight the basic parameters of rock, the controllable parameters in the equation are standardized. The calculated wear degree can better reflect the wear ability of rock to drill bit. This result is of great significance for the factor prediction of formation abrasiveness and bit selection.

Modeling of Gear-Hone Teeth with Consideration of Elasticity, Correction, and Operational Wear

Gear hones are used as tools for gear honing. The efficiency of using gear hones mainly depends on the parameters of their compound material, first of all on the wear resistance and elasticity modulus. In terms of the elasticity modulus, gear hones can be hard and elastic, depending on the bonding agent type. Experience shows that gear-hone teeth distort during gear honing; they feature contact and flexural deformation and wear during metal removal, including along the tooth space. For this reason, it is necessary to consider the deformation and wear values for designing of gear hone geometry. An approach for calculation of variable engagement parameters, using a geometrical model in the form of sliding trapezoids to consider the dimensional wear of gear-hone teeth based on the positive correlation factor of the original profile. Such designing of gear-hone teeth provides sufficient thickness in the original section, which ensures high performance capacity of gear-honing tools and required workability.

The dentine-sealer interface: Modulation of antimicrobial effects by irrigation.

AimAssess whether sodium hypochlorite (NaOCl) or chlorhexidine (CHX) and two irrigation protocols may alter the antibacterial properties of dentine and three endodontic sealers using a novel ex vivo tooth model.MethodologyPrior to antibacterial testing, the tooth model was validated by means of scanning electron microscopy (SEM) to evaluate the separation between dentine and sealer surfaces. Root blocks prepared from extracted human roots were pre‐treated with 17% EDTA + 0.9% saline and subsequently treated with 1% NaOCl (G1), 2% CHX (G2) or no irrigant (G3). Two irrigation protocols were further investigated, “1% NaOCl + 17% EDTA” (P1) and “1% NaOCl + 17% EDTA + 2% CHX” (P2). Following irrigation, the root blocks were either filled with AH Plus, BioRoot RCS and Pulp Canal Sealer (PCS), or left empty. All groups were incubated for 1, 7 and 28 days. Direct contact tests for planktonic E. faecalis and 48 h E. faecalis biofilms were performed at the level of dentine and sealer surfaces. Statistical analysis was performed on the bacterial survival between irrigants (G1, G2 and G3) and between irrigation protocols (P1 and P2); p < .05.ResultsThe model was considered reproducible as SEM examination of dentine samples indicated consistent separation between dentine and sealer surfaces. Irrigation with CHX (G2) and irrigation protocol P2 enhanced the antibacterial properties of dentine without sealer application as well as dentine in contact with all three sealers tested, especially against planktonic E. faecalis. G2 and P2 also improved the antibacterial effect of AH Plus surfaces for all three incubation times. No irrigation groups (G1, G2) or irrigation protocols (P1, P2) altered the antibacterial properties of BioRoot RCS surfaces against planktonic bacteria or biofilms. Only BioRoot RCS surfaces eliminated the planktonic E. faecalis in all irrigation groups (G1, G2, G3) and protocols (P1, P2) investigated whilst PCS surfaces eliminate E. faecalis in biofilms in all groups up to 7 days.ConclusionsThe tooth model was reproducible. CHX improved the antibacterial activity upon both sealer and dentine surfaces. Amongst sealers, BioRoot RCS was less affected by NaOCl and CHX, and exhibited high antibacterial properties regardless the irrigation applied.

Effect of hydroxyapatite based agents on the bonding properties of universal adhesives

Objective: To study the effect of hydroxyapatite (HA) based agents on the bonding properties of universal adhesive with different application modes, and to provide evidence for the use of adhesives after desensitization treatment. Methods: Sixty impacted third molars were extracted and selected (acquired from Department of Oral and Maxillofacial Surgery, College of Stomatology, Xi'an Jiaotong University). Four third molars were used to prepare 1 mm thick dentin disks and treated with 1% citric acid to simulate sensitive tooth models. The dentin surfaces were observed by scanning electron microscope (SEM) after treating with no desensitization (control group), desensitized by HA based toothpaste Biorepair and Dontodent Sensitive respectively (desensitizing toothpaste A group and B group), or HA paste treatment (desensitizing paste group ) (n=2 per group). The remaining teeth were selected to expose the mid-coronal dentin and establish dentin sensitivity models. Then, the specimens were divided into 4 former groups and received corresponding treatment. Each group was randomly divided into 2 subgroups, and intermediately strong universal adhesive (G-Premio Bond) was applied on the desensitized dentin by either etch-and-rinse mode or self-etch mode. Resin-dentin slice specimens (n=4 per subgroup), microtensile specimens (n=20 per subgroup) and slice specimens (n=6 per subgroup) were prepared. The microstructure and nanoleakage of the adhesive interfaces were observed by scanning electron microscopy (SEM). The microtensile strength (bond strength) and fracture mode were tested and recorded. The water permeability of the adhesive interface was observed by laser scanning confocal microscopy (LSCM). Results: SEM showed that desensitizing toothpaste and desensitizing paste could partially or entirely occlude most of the dentin tubules. For the etch-and-rinse mode, the bond strength of specimens treated with toothpaste A [(40.98±4.60) MPa], toothpaste B [(40.89±4.64) MPa] and HA paste [(41.48±3.65) MPa] was significantly higher than that of the control group [(38.58±4.28) MPa] (F=3.89,P<0.05). There was no statistically significant difference in bond strength among the 4 subgroups for self-etch modes (F=0.48,P>0.05). After desensitization, the bond strength of the control group and desensitizing groups in the self-etch mode was significantly higher than that in the etch-and-rinse mode (P<0.05). The overall fracture modes were mixed failure and interfacial failure in the control group and desensitizing groups. SEM showed speckled silver-stained particles deposited along the bottom of the hybrid layer on the bond interface of etch-and-rinse mode, and there were few silver-stained particles deposited on the bond interface of self-etch mode. LSCM showed continuous linear penetration in the hybrid layer of etch-and-rinse mode subgroups and discontinuous linear penetration in the hybrid layer of self-etch mode subgroups. Conclusions: HA based desensitizers have no adverse effect on the bond strength of intermediately strong universal adhesive and show good bonding performance accompanied with the self-etch mode.

To Compare the Stress Magnitude on Roots of Mandibular Incisors at Different Inclinations With Different Arch Wires During Intrusion Mechanics—A Fem Study

Introduction: Force is applied through brackets in fixed mechanotherapy which generates stress in periodontal ligament and root of the teeth and is difficult to measure directly. Finite element analysis is used as a solution for understanding this biomechanical response. So the aims and objectives of this study were to evaluate the stress magnitude induced in the labial and lingual surface of mandibular incisors using superelastic NiTi arch wires of different cross-section at different inclination through finite element analysis. Materials and Methods: Finite element model of all mandibular teeth including periodontal ligament, alveolar bone, buccal tubes, brackets, and arch wire were constructed using mechanical elastic properties of the materials. Three different NiTi arch wires, round (0.016″), square (0.016″ × 0.016″), and rectangular (0.016″ × 0.022″), were placed into the bracket slots and models were constructed which were analyzed for stress distribution on root surface and periodontal ligament with 3 different cross-sections at 90°, 100°, and 110° with Ansys Version 14 software. Conclusion: Labial stress was found highest in round arch wire as compared to square and rectangular wire. Lingual stress was found to be slightly more in rectangular wire as compared to round and square arch wire.

Biomimetic remineralization of human dentine via a “bottom-up” approach inspired by nacre formation

Nacre exhibited noticeable similarities in fundamental material buildup and biological characteristics with tooth hard tissue, so the present study aims to achieve bionic dentine remineralization by duplicating nacre's “bottom-up” assembly concept. Inspired by nacre's mineralization mechanism, the present project starts to synthesize a “seawater-like” mineralizing precursor medium, then monitor its in vitro dentinal tubules occlusion effect, acid-resistant stability, the “fingerprint” dynamic components change in real time on in vitro sensitive tooth model as well as its in vitro cellular biological response towards human dental pulp stem cells. For the further exploration, a single-layer fibrillar collagen model was established to simulate the exposed collagen of demineralized dentine to appraise its intrafibrillar mineralization effect. The results demonstrated that the application of “seawater-like” mineralizing precursor medium effectively occluded dentinal tubules, reduced dentine permeability, increased surface microhardness, provided certain acid-resistant stability and possessed favorable in-vitro biocompatibility. In addition, the dynamic procedure of hierarchical intrafibrillar nanocrystalline assembly was observed, which offered a clue to uncover its remineralizing mechanism. It is attainable to realize the biomimetic remineralization of human dentine via the “bottom-up” concept inspired by nacre structure duplication, suggesting great potential for providing dentists a therapeutic strategy to counter dentine hypersensitivity in the future.

Tracing PRX1+ cells during molar formation and periodontal ligament reconstruction

Neural crest-derived mesenchymal stem cells (MSCs) are known to play an essential function during tooth and skeletal development. PRX1+ cells constitute an important MSC subtype that is implicated in osteogenesis. However, their potential function in tooth development and regeneration remains elusive. In the present study, we first assessed the cell fate of PRX1+ cells during molar development and periodontal ligament (PDL) formation in mice. Furthermore, single-cell RNA sequencing analysis was performed to study the distribution of PRX1+ cells in PDL cells. The behavior of PRX1+ cells during PDL reconstruction was investigated using an allogeneic transplanted tooth model. Although PRX1+ cells are spatial specific and can differentiate into almost all types of mesenchymal cells in first molars, their distribution in third molars is highly limited. The PDL formation is associated with a high number of PRX1+ cells; during transplanted teeth PDL reconstruction, PRX1+ cells from the recipient alveolar bone participate in angiogenesis as pericytes. Overall, PRX1+ cells are a key subtype of dental MSCs involved in the formation of mouse molar and PDL and participate in angiogenesis as pericytes during PDL reconstruction after tooth transplantation.

Crucial errors identification of worm grinding process of face gears based on tooth flank posture error model and their influences on tooth flank errors

Crucial errors identification of worm grinding process of face gears based on tooth flank posture error model and their influences on tooth flank errors

Photoelastic models applied to dental restorations

To improve the understanding of the changes generated by restorative procedures through photoelastic models. Dental reconstruction should be based on principles of occlusion in order not to cause premature contact points during preparation and restoration procedures that can lead to disorders such as occlusal trauma, temporo-mandibullary joint dysfunction, or fractures. This paper presents a didactic method to objectively visualize occlusal loads and their distribution. Photoelastic models of teeth and maxillary segments were made to visualize the effects of dental preparations and restorations, as well as the wear of premature contact points. The direction, intensity and distribution of stresses in the crown and bone support were analyzed by photoelasticity. The technique allows visualization of how the structures are affected from the cavity preparation, the different stresses with diamond or carbide burs, in addition to observing how a premature contact point not only affects the organ that contains it but also the surrounding structures.

Osteotomy training for dental students using three-dimensional simulation software and maxillofacial three-dimensional-printed models.

Simulated educational models of teeth, bones, and gums have been used for a long time in procedural skills training in dentistry. The advent of three-dimensional (3D) printing technologies and additive manufacturing has facilitated the production of more advanced 3D printed models that can be utilized for surgical and dental training together with other technologies (e.g., 3D scanners and image analysis software). We conducted training on osteotomy in the maxilla and mandible using maxillofacial simulation software (MSS) and a 3D-printed model for 5th-year undergraduate dental students (13 students in 2017 and 11 students in 2018 with more than half of their results). We compared the group (13 students) who performed osteotomy after participating in the simulation lecture with those (11 students) who performed osteotomy after performing self-simulation (they were instructed to bring their personal computers and install the MSS) using tests and questionnaires (pre- and post-curriculum). The average test score was significantly higher in the group who performed osteotomy using the 3D-printed model after performing self-simulation; participants in this group had acquired a better understanding of the surgical procedure. Comparison using questionnaires showed a significant difference in the students' understanding of instruments and surgical techniques between both groups. The MSS and 3D printed models are widely used clinically. Incorporating these in the curriculum will help accelerate student development. In addition, prompt education on the purpose and usefulness of these tools will not only facilitate simulation software and 3D-printed model-based treatment plan in the clinic but also promote further research.

Generating Training Data Using Python Scripts for Automatic Extraction of Landmarks from Tooth Models

The automatic extraction of landmarks from three-dimensional tooth models using artificial intelligence is crucial to advance dental anatomy studies. However, collecting sufficient data for artificial intelligence training hinders progress in this field. To automatically identify anatomical landmarks on tooth models, this paper proposes a method for generating substantial amount of training data from the digital data of a single human maxillary canine. Human maxillary canine data were loaded into Blender, and the landmark was defined as the cusp of the canine. Sequentially, the coordinate values of the centroid of the landmark were used as correct answer labels. A total of 22,896 training images were generated using Python scripts, and they were split into train and validation datasets. Pairs of images and label data were fed into the artificial intelligence network, which comprises four convolutional layers and one max pooling layer. The accuracy of the trained artificial intelligence was evaluated on 915 200 × 200 pixel images, which were different from the training images. The average Euclidean distance error of the artificial intelligence-predicted coordinate values of the landmark was 6.1 pixels. Our approach, based on the training data generated in Blender using Python scripts, provides a powerful solution when it is challenging to obtain sufficient amount of medical field data for artificial intelligence-assisted procedures.

Histologic evaluation of dentin bridge formation by pachymic acid and biodentine in human tooth culture model

Histologic evaluation of dentin bridge formation by pachymic acid and biodentine in human tooth culture model

A covering model of 3d-teeth analysis for holes filling

This paper discusses the construction and implementation of teeth holes filling mathod. The architecture and model of the combination of PONN multi-layer to cover teeth and fill holes of teething. Finally, the position of teeth is found, and the tooth model is placed through 3D space. Experimental results show that the method has good expansibility and superiority.

Reinforcing an immature tooth model using three different restorative materials

To compare and evaluate the strength rendering capacity of three restorative materials in tooth model simulated as immature teeth. In this in vitro study, 80 human maxillary permanent central incisors scheduled for periodontal extraction were collected, and an immature tooth model was prepared using a 3 mm twist drill. To simulate single-visit apical barrier, all the teeth were prepared with peso number 1-6. The teeth were segregated into three experimental and a control group. The experimental groups (n = 20) comprised of fiber-reinforced composite (FRC), Biodentine, and glass ionomer cement. The fracture resistance of all the teeth was tested using universal testing machine. The final reading of the applied load to cause fracture was noted and later was subjected to statistical analysis, P ≤ 0.05 was considered statistically significant, and the level of significance was fixed at 5%. Student's t-test was applied to compare values among experimental groups. There was a significant difference in the values of peak load resulting in fracture among experimental groups which was observed statistically (P ≤ 0.001). FRC exhibited superior reinforcing capacity (mean: 1199.7 N) among the experimental materials followed by Biodentine and Bioglass R. The lowest value to fracture was observed in control group (mean: 236.7 N). The results indicate that FRC could substantially contribute positively in reinforcing the simulated thin-walled immature roots.

Frequently applied ketamine, medetomidine and thiopental anaesthesia induces high mortality in Wistar rats.

Fatal reactions to the combination of ketamine-medetomidine and thiopental in Wistar rats are described in two different models of orthodontic tooth movement. Thirty male rats were divided into two groups that required repeated anaesthesia during a 42-day study period, once a week or more frequently depending on the experimental group. The combination of ketamine [50 mg/kg body weight (b.w.)] and medetomidine (67 µg/kg b.w.) was administered intraperitoneally. Thiopental (8.3 mg/kg b.w.) was administered intraperitoneally 5 minutes later, barring any observable adverse reactions to the anaesthesia. Twelve animals died, though none during the first two procedures. Three animals died shortly after the administration of a ketamine-medetomidine combination, and the remainder died 10-25 minutes later. Only four of the affected animals received thiopental before their death on a particular day. As ten rats died in the more frequently anaesthetized group, repeated anaesthesia was suspected to be the cause of the increased mortality. Obstruction of the respiratory airways by saliva with subsequent suffocation may have been one of the causes of death, as it appeared in all the affected animals. Although the combination of ketamine and an alpha-2 adrenergic agonist is generally considered to be safe in rats, we propose that studies utilizing protocols requiring repeated anaesthesia adhere to a minimum safety period of 8.5 days between anaesthesia events. Alternative anaesthetic protocols should be employed if adherence to this is not possible due to the nature of the study.

Окремі підходи до виконання художніх реставрацій фронтальних зубів у пацієнтів молодого віку: Аналіз літератури та опис клінічного випадку

Resume. The problem of aesthetics in dental work (such as artistic restoration of teeth, orthopedic dentures, restoration of marginal periodontal tissues, teeth whitening and cosmetic modifications) remains relevant for domestic dentistry for a long time. Today it is standard practice to determine the criteria of aesthetics of dental work individually for every patient. Today, clinicians often ask the questions «How can you describe the features of the teeth of a young patient?», «Is it possible by performing aesthetic restoration using a special method to achieve the perception of the face as younger?». It has been found that teeth in young patients have a number of special features that can be used in the restoration of teeth, in some cases to create a younger perception of the patient's face. For example, the elongated shape of the teeth may play a role in contouring the face, changing the perception of its width. Nowadays, in addition to personal aesthetic perception of the results of work and harmony of the smile by the doctor, a number of mathematical proportions are used which reflect the anatomy and aesthetics of the smile and are an attempt to unify the preconditions for determining the artistic quality of dental treatment. Today, a number of works are known on the artistic restoration of teeth and modeling of artificial teeth which determine the parameters and proportions of the aesthetics of a smile, which include important elements of its design. Such proportions include the «golden ratio», «golden percentage», Preston’s ratio and RED-proportion – all of tham allow us to describe mathematically the aesthetics of the frontal area of the upper dentition in humans. Conclusions. The use of special approaches in the implementation of artistic restorations of teeth in young patients is an option to improve the protocol of restoration of dental crowns, which leads to a higher aesthetic and functional result of dental work. Key words: teeth, restoration, aesthetics, proportions, young age, signs.

Effects of abutment tooth and luting agent colors on final color of high-translucent zirconia crowns.

This study aimed to evaluate the effects of the tooth portion evaluated and the colors of the abutment tooth and resin luting agent on the final color of monolithic zirconia crowns. Monolithic zirconia crowns were fabricated for left maxillary central incisors using two shades (A2 and A3) of highly translucent monolithic zirconia disks. A model of the abutment tooth was fabricated using resin core materials (white: W; dentin: D). The color of the crowns was measured with try-in pastes (clear: C; brown: B) as a resin-luting agent substitute. The measurement was performed after placing the crown on the model with the attached abutment tooth with try-in paste. The color of three labial portions (cervical, body, and incisal) was evaluated using a dental spectrophotometer. The color difference (ΔE) between the CIELab values of the zirconia disks and the final measurement of zirconia crowns was calculated. The ΔE between the crown of the A2 shade and the zirconia disk of the A2 shade had the highest ΔE value in the body portion with W-B (ΔE=3.92). Similarly, the A3 shade had the highest ΔE value in the cervical portion, with W-B (ΔE=4.27). The results of three-way ANOVA showed that the ΔE values were influenced by the tooth portion evaluated and the color of the abutment tooth. The final color of the monolithic zirconia crowns was significantly influenced by the tooth portion evaluated and the color of the abutment tooth.