Crown Preparation Research Articles

Qatar dental student perceptions of Sirona prep-check software for learning crown preparations.

Contemporary dental education requires swift assimilation of technological advancements to prepare the future generation of dentists. Integrating digital tools, such as prepCheck software in crown preparations offers a promising avenue for enhancing the learning experiences of dental students. This study aimed to evaluate the perceptions and experiences of undergraduate dental students regarding the use of PrepCheck software for learning crown preparations. An interventional study design was employed to investigate the perceptions of undergraduate dental students regarding the use of Sirona prepCheck software their learning experiences in the prosthodontics course at the College of Dental Medicine. were recruited using purposive sampling. Participants received training on crown preparations using standard didactic and practical teaching methods. A total of 64 dental students (Mean age 22.4years) participated in the study. They were randomly assigned to two groups, 32 participants each. The study group utilized prepCheck software and the control group relied solely on supervisor feedback. Both groups completed their crown preparation labs concurrently, ensuring consistency in training and assessment conditions. Out of a total number of 66 students enrolled on the course, 64 participated in the study giving a response rate of 96.96%. The overall mean score for all items was 1.01 (95%CI 0.77-1.25), indicating positive perceptions of the participants about prepCheck software. Analysis of variance revealed no significant variation by gender. Thematic analysis of open-ended items identified key themes related to the advantages and challenges of using prepCheck. Advantages included immediate self-evaluation, objective analysis, and feedback, while challenges included operational difficulties and cost concerns. This study provides insights into the effectiveness of prepCheck in dental education, offering perspectives derived from both quantitative and qualitative analyses. A majority of the participants recommended that digital assessment should be integrated with conventional methods, underscoring the importance of human input through supervisor feedback. The study demonstrates the potential of prepCheck software in enhancing participants' learning experiences in crown preparation assessment. While digital tools offer advantages such as self-evaluation and objective analysis, they need to be supported with input and feedback from the supervisors.

Intra and inter-individual differences in the visual evaluation of crown preparations in the phantom head

Intra and inter-individual differences in the visual evaluation of crown preparations in the phantom head

Effectiveness of virtual reality glasses with integrated sign language in reducing dental anxiety during pulpotomy in children with hearing impairment: a randomized controlled trial

BackgroundChildren with hearing impairment (HI) face communication challenges during dental procedures due to hearing loss. Studies suggest that distraction techniques, like virtual reality (VR), can effectively divert their focus from stressful stimuli, resulting in a more comfortable dental experience. The present study aims to assess the effectiveness of distracting children with moderate to severe (HI) with virtual reality glasses that show cartoons in sign language during pulpotomy treatment compared to conventional management techniques.MethodsForty children aged five to seven participated in a randomized controlled parallel two-arm clinical trial—the type of behavioral management employed determined which two groups children were randomly placed into. Group I (Study group) used virtual reality glasses as a diversion, while Group II (Control group) used the conventional behavior management approach. Local anesthesia was administrated, and a pulpotomy procedure was performed on the selected tooth, followed by stainless steel crown restoration (SSC). There were three methods used to assess dental anxiety before and after the procedure: the physiological method, which used heart rate (HR); the objective measure, which used the Venham Clinical Anxiety Scale (VCAS); and the subjective measure, which used the modified Facial Affective Scale (FAS). An independent t-test was employed for HR analysis of the difference between the groups as a continuous variable. The Pearson Chi-square test assessed differences between groups for categorical variables, such as (VCAS) (FAS).ResultsNo significant differences were found in mean (HR) or (VCAS) between the two groups throughout the procedures: during local anesthesia (p = 0.659, 0.282), pulpotomy (p = 0.482, 0.451), and stainless steel crown preparation (p = 0.090, 0.284). Anxiety levels by (FAS) remained statistically comparable between the two groups before and after the procedures (p = 0.507, 0.749), respectively.ConclusionsThe use of VR glasses revealed no significant advantages in managing children with HI during the dental visit compared to the conventional method of child behavior management.Trial registrationThe trial was prospectively enrolled on 11/11/2023 under the identification number NCT06153823 on ClinicalTrials.gov.

Utilizing 3D Model and Comparison Software Tools in Improving Assessment Methods: A Pilot Study

Purpose/Objectives: This manuscript investigates the effectiveness of computer-assisted design and manufacturing (CAD/CAM) technology in preclinical dental education. The COVID-19 pandemic created a need for remote teaching approaches. In preclinical fixed prosthodontics courses, traditional evaluation methods rely on faculty to visually grade laboratory projects utilizing rubrics and 2D images. Assessment and feedback vary amongst faculty, and faculty calibration has been inconsistent in reducing intra-and inter-rater variability. This study aimed to compare faculty assessment of student full coverage crown (FCC) preparations traditionally versus digitally through 3D model visual assessment and/or comparative analysis software reports. Methods: Eighteen UTHealth Houston School of Dentistry faculty participated, each randomly assigned into one of three assessment groups: traditional visual Group (TV), 3D Group (3D), and 3D visual assessment supplemented with comparative analysis software report (3D+) Group. Faculty graded the same eight lithium disilicate typodont preparations for all three assessment groups. Results: Survey results showed the ease of use and efficiency among the three assessment methods varied significantly. Grading scores revealed that axial wall reduction significantly differed among the three assessment methods. Conclusion: This study concludes that the combination of the two digital assessment methods can overcome the limitations of traditional evaluation methods and digital methods alone by providing objective feedback to students and enhancing their learning experience.

Analysis of occlusal clearance of crown preparations in a predoctoral clinical setting.

This study sought to assess the presence and location of inadequate tooth preparation performed by predoctoral dental students by scanning mounted casts submitted for monolithic zirconia crown fabrication METHODS: An intraoral scanner capable of volumetric measurements of crown preparations was used to analyze 56 crown preparations on mounted stone casts before submission to a lab for crown fabrication. The mounted casts were scanned individually and then a buccal bite was scanned to stitch the models together into virtual occlusion. The distance between the crown preparations and opposing dentition was displayed volumetrically, and the minimum clearance of each preparation was recorded for both the functional and non-functional cusps. Preparations were evaluated for adequate interocclusal clearance and comparisons were made using a Chi-square test with α=0.05 with respect to tooth location, functional versus nonfunctional cusp, and or single versus multi-unit preparation. Over 47% of mounted casts with crown preparations analyzed for the study exhibited a lack of occlusal clearance in at least one area. Functional cusps were more often under-reduced than non-functional (p<0.001). No other comparisons were statistically significant. The present study demonstrates a high percentage of under-reduced crown preparations in a predoctoral clinic and emphasizes the utility of quality control and analysis via digital scanning of crown preparations prior to crown fabrication.

The potential integration of Simodont® Dental Trainer in different stages of the dental curriculum

BackgroundThe lack of standardised studies remains an obstacle to developing a consistent approach to integrating virtual dental simulation (VDS) into dental education. The aim of this study was to develop consensus among experienced educators and dental practitioners on the optimal integration of VDS at various stages of dental curricula. The goal was to propose clear yet flexible recommendations that could be implemented by most educational institutions. MethodsFocus groups were established, consisting of experienced academic educators involved in VDS, experienced academic staff who had not previously been involved in VDS, and experienced dental practitioners. These groups exchanged ideas about the best ways to integrate VDS into dental curricula. The Simodont® Dental Trainer system was used to design a curriculum for VDS. ResultsThe expert group agreed that VDS for manual dexterity exercises should be introduced in the first year of dental curricula. This should be followed by cariology exercises in the second year and crown preparation exercises in the third year, alongside traditional manikin-based simulation exercises. Additionally, VDS was recommended for senior students on an ad hoc basis for academic recovery purposes. However, VDS endodontic exercises were excluded from the proposed integrative dental curriculum. Other ways of utilising VDS were identified, such as student recruitment activities and intensive refreshment programs at the start of each academic year. ConclusionsThis study proposes a flexible approach to including VDS in dental curricula. This proposed approach can be customised to meet the specific needs of each educational institution, providing a tailored learning experience for students.

Influence of apical finish line location of tooth preparations on the scanning accuracy of intraoral scanners with various focal lengths and scanning technologies

Statement of problemLimited studies have reported the influence of finish line location on the accuracy of intraoral scanners (IOSs). Focal length is a hardware characteristic of IOSs. Whether there is a relationship between scanning accuracy of tooth preparations with the finish located at different apical positions and focal length and IOS technology or system remains uncertain. PurposeThe purpose of the present in vitro study was to assess the influence of the apical finish line location of tooth preparations on the accuracy of 4 IOSs with various focal lengths and scanning technologies. Material and methodsA maxillary typodont with a crown preparation on the left first molar was digitized (T710). Afterwards, a removable die was created on the prepared first molar of the virtual cast and duplicated to create 4 dies with different apical finish line locations: 2- or 1-mm supragingival, 0-mm or equigingival, and −0.5-mm or intracrevicular. The cast and die designs were additively fabricated (Asiga Pro 4K with Keystone Model Ultra). Each die was independently scanned by using the same laboratory scanner (reference scans). Four groups were created: TRIOS 5, i700, iTero, and Primescan. Four subgroups were developed depending on the apical position of the finish line (n=15). In each subgroup, the cast was assembled by positioning the corresponding die into the cast. The cast was then scanned by using the corresponding IOS. The reference scans were used as a control to compute the root mean square (RMS) error discrepancies with each experimental scan on the preparation and margin of the preparation areas. Two-way ANOVA and pairwise comparisons were used to analyze trueness (α=.05). The Levene and pairwise comparisons using the Wilcoxon Rank sum test were used to analyze precision (α=.05). ResultsTrueness discrepancies in the preparation area were found among the groups (P=.010) and subgroups (P<.001), with a significant interaction between group×subgroup (P<.001). The −0.5 mm location obtained significantly worse trueness in the preparation area. The TRIOS 5 and i700 obtained the best trueness in the preparation area. Trueness discrepancies in the margin area were found among the groups (P=.002) and subgroups (P<.001), with a significant interaction between group×subgroup (P=.004). The −0.5 mm location obtained the worst trueness in the margin area. The i700 and Primescan obtained the best trueness in the margin area. Precision discrepancies were found in the preparation area (P<.001). The TRIOS 5 obtained the best precision in the preparation area (P=.001). Precision discrepancies in the margin area were obtained (P<.001). The 1-mm subgroup obtained the best precision (P=.001). ConclusionsThe apical position of the finish line of the tooth preparation tested affected the trueness and precision of the IOSs tested.

Application of artificial intelligence in dental crown prosthesis: a scoping review

BackgroundIn recent years, artificial intelligence (AI) has made remarkable advancements and achieved significant accomplishments across the entire field of dentistry. Notably, efforts to apply AI in prosthodontics are continually progressing. This scoping review aims to present the applications and performance of AI in dental crown prostheses and related topics.MethodsWe conducted a literature search of PubMed, Scopus, Web of Science, Google Scholar, and IEEE Xplore databases from January 2010 to January 2024. The included articles addressed the application of AI in various aspects of dental crown treatment, including fabrication, assessment, and prognosis.ResultsThe initial electronic literature search yielded 393 records, which were reduced to 315 after eliminating duplicate references. The application of inclusion criteria led to analysis of 12 eligible publications in the qualitative review. The AI-based applications included in this review were related to detection of dental crown finish line, evaluation of AI-based color matching, evaluation of crown preparation, evaluation of dental crown designed by AI, identification of a dental crown in an intraoral photo, and prediction of debonding probability.ConclusionsAI has the potential to increase efficiency in processes such as fabricating and evaluating dental crowns, with a high level of accuracy reported in most of the analyzed studies. However, a significant number of studies focused on designing crowns using AI-based software, and these studies had a small number of patients and did not always present their algorithms. Standardized protocols for reporting and evaluating AI studies are needed to increase the evidence and effectiveness.

Clinical applications and improvement of resin bonding for PEEK in resin-bonded fixed dental prosthesis: A review

Resin-bonded fixed dental prostheses (RBFDPs) are a commonly used precision treatment, such as fixed dental prosthesis (FDP) and implant-supported dentures. Full crown preparation of vital teeth, which is required for traditional FDPs, may result in a risk of pulp reaction as a large portion of the coronal tooth structure must be removed. RBFDP has been recognized as a non-invasive or minimally invasive treatment modality for the replacement of single missing teeth. RBFDPs require much less tooth preparation than conventional FDPs. These dental treatments are restorative solutions used to cover missing teeth and achieve an aesthetic smile. The biomechanical rules, aesthetics, polishability, and bond strength have been emphasized in RBFDP treatments. Polyetheretherketone (PEEK) is one of the most widely used biomaterials in dentistry. The material, which stands out especially with its acceptable aesthetics, biocompatibility and modulus of elasticity close to dentin, has enabled it to be used in RBFDP treatments. Since PEEK is lighter than metal alloys, patients experience less discomfort and a feeling closer to natural teeth. Furthermore, the thermoplastic properties of PEEK are claimed to provide a precise fit, allowing the restoration to better integrate into the natural tooth structure. In addition, its ability to be customized using different modern manufacturing techniques is thought to offer dentists and patients a reliable option for successful long-term treatment. Our review is about the use of PEEK material as an alternative material in RBFDPs with low negative effects on periodontal tissues and their bonding with resins.

Effect of loupe and microscope on dentists’ neck and shoulder muscle workload during crown preparation

Although there is consensus among dentists that visual aids not only improve vision but also help improve posture, evidence is scarce. This study aimed to evaluate the effect of visual aids (loupe and microscope) on the muscle workload of dentists during crown preparation on dentiform first molars in each quadrant of a phantom head, considering dentists’ muscles, patients’ tooth positions and surfaces. Six right-handed dentists from a single tertiary hospital participated. Surface electromyography device recorded the muscle workload of the bilateral upper trapezius, sternocleidomastoid, cervical erector spinae, and anterior deltoid during crown preparation. The results showed significantly lower workload in all examined muscles when using a microscope compared to the naked eye (p < 0.05), whereas the loupe showed reduced workload in some specific muscles. The muscle with the highest workload for all visual aids was the cervical erector spinae, followed by the upper trapezius. When analyzed by tooth surface, while the loupe did not significantly reduce overall workload compared to the naked eye for each surface, the microscope significantly reduced workload for most surfaces (p < 0.05). Therefore, during crown preparation, the workload of the studied muscles can successfully be reduced with the use of a loupe or microscope.

Comparative Evaluation of Polymethyl Methacrylate and Thermoforming Crowns as Semipermanent Crowns in Primary Molars: An In Vivo Study.

The present randomized clinical trial is aimed at evaluating clinical efficiency of two different types of esthetic crowns-polymethyl methacrylate crowns and vacuum formed thermoformed crown as an alternative to full-coverage coronal restoration for deciduous molars. A total of 45 primary molars in pediatric patients were selected using randomization and split into three groups based on the technique used for preparation of crowns: group I-polymethyl methacrylate crowns; group II-thermoformed crown; and group III-stainless steel crowns (SSC). All crowns were clinically and radiographically evaluated at baseline, 1st month, and 3rd month for gingival health, retention, marginal integrity, proximal contacts, occlusion, alignment, and staining. The data was tabulated and analyzed by Statistical Package for the Social Sciences (SPSS) Version 23.0 software. The intergroup comparison was done by Kruskal-Wallis test, analysis of variance (ANOVA), and Mann-Whitney U test for continuous data. The intragroup comparison was done by Friedman test and Wilcoxon signed-rank test for categorical data. All p-values < 0.05 were considered statistically significant. With regard to the parameters of plaque score, gingival index score, occlusion, interproximal contacts, retention, alignment, and marginal adaptation, no statistical significance was noted between the three groups. However, with regard to the discoloration (staining) when the polymethyl methacrylate acrylic (PMMA) group was compared with thermoforming group, statistical significance was noted in 1st month with p-values of 0.04 and 0.03, respectively. On intragroup comparison, statistically significant values were obtained in SSC group for plaque score and thermoforming group for gingival index score. The study concluded that the PMMA and thermoforming crowns can be used as an alternative to SSC for restoring the primary molars as they showed equivalent results to that of standard SSC. Matha N, Kumar KS, Reddy BVT, et al. Comparative Evaluation of Polymethyl Methacrylate and Thermoforming Crowns as Semipermanent Crowns in Primary Molars: An In Vivo Study. Int J Clin Pediatr Dent 2024;17(S-1):S43-S54.

Evaluation of Convergence Angles in Posterior Crown Preparations by Dental Students at Zawia University

Background and objectives: Achieving optimal axial taper and occlusal convergence in crown preparations is a crucial concern among dental students. Proper preparation design is essential for the long-term success of full-coverage restorations. This study aimed to evaluate the convergence angles and axial taper achieved by dental students in their crown preparations. Methods. A total of 80 posterior tooth preparations (40 mandibular first molars and 40 mandibular second molars) created by second-year dental students on a dental simulator were analyzed. The total occlusal convergence (TOC), bucco-lingual (BL) and mesio-distal (MD) convergence angles, as well as the degree of taper on the axial walls, were measured using the B&amp;B dental software (Guide system, B&amp;B, Italy). Statistical analysis was performed using SPSS version 27. Results. The overall mean of the total convergence angle was 21.88°, with a BL convergence angle mean value of 23.11° (standard deviation of 13.3°) and an MD convergence angle mean value of 20.66° (standard deviation of 11.0°). The results showed a statistically significant difference between the mesial axial taper and the distal axial taper (p-value &lt; 0.001). However, no significant differences were observed between the buccal axial taper and lingual axial taper (p-value &gt; 0.05), or between the BL convergence angle and MD convergence angle (p-value &gt; 0.05). Conclusion. The study revealed variations in the convergence angles of full metal crown preparations created by dental students. The recommended convergence angle was difficult for these students to achieve.

The Effect of Student Experience and Tooth Location on Finish Line Width and Angle of Full Metal Crown Preparations in Preclinical Setting.

To determine the effect of experience and tooth location on the finish line width and angle of crown preparations performed by undergraduate students. Eighty full metal crown preparations on typodont teeth were divided into four groups: Group 1: 20 preparations performed on mandibular first molar in the first semester. Group 2: 20 preparations performed on mandibular first molar in the second semester. Group 3: 20 preparations performed on mandibular second molar in the first semester. Group 4: 20 preparations performed on mandibular second molar in the second semester. All prepared teeth were scanned, and the finish line width and angles were measured at 8 different locations. Paired t-test in the SPSS software was used to compare and determine the effect of experience and tooth location on the students' performance. There was a statistically significant difference in the mandibular first molar finish line width between the first and second semesters for the same student in the distal, distolingual, and mesiobuccal areas of the tooth. There was a statistically significant increase in finish line width between first and second molars in the distobuccal, distal, distolingual, lingual, and mesial side of the tooth. Regarding the finish line angle, there was a statistically significant difference between the first and second semesters on the distal side of the tooth. There was a statistically significant increase in finish line angle between first and second molars in the distobuccal side of the tooth. As students gain more experience in different types of tooth preparations, they tend to produce a wider finish line than that recommended for full metal crown preparation. The tooth location in the mouth influences the width and angle of the finish line hence the more inaccessible areas on the tooth have a wider finish line.

Analysis of the Pulpal Blood Flow Microdynamics during Prosthetic Tooth Preparation Using Diamond Burs with Different Degrees of Wear.

Pulpal modifications taking place during prosthetic tooth preparation using worn-out burs may represent a risk for the vitality of the dental pulp. The aim of this in vivo study was to evaluate whether the wear of diamond burs has an influence on the vascular microdynamics at the level of the dental pulp, during vertical preparation for zirconia crowns. The study was performed with a split-mouth design and included 32 vital permanent monoradicular teeth (20 maxillary and 12 mandibular), from six subjects, aged between 20 and 50 years. The teeth were randomly assigned to two study groups of 16 teeth each. For prosthetic preparation, new burs were used in the first group, and burs at their 5th use were used in the second group. Four consecutive determinations of the pulpal blood flow by Laser Doppler flowmetry (LDF-laser Doppler MoorLab instrument VMS-LDF2, Moor Instruments Ltd., Axminster, UK) were taken for each tooth included in the study: before the preparation (control values), immediately, at 24 h, and at 7 days after the prosthetic preparation. A four-way ANOVA statistical analysis was applied to analyze the effect of four considered factors (bur wear degree, time of measurement, tooth number, and tooth location) on the pulpal blood flow (PBF). A significant increase in pulpal blood flow compared to the baseline was recorded immediately after preparation (p < 0.01), at 24 h (p < 0.01), and at 7 days (p < 0.05) in both groups, but more pronounced in the case of burs at the 5th use. The blood flow was significantly higher in upper jaw teeth, irrespective of the measurement time. In conclusion, the use of worn-out diamond burs produces lasting modifications in the pulpal blood flow of teeth that undergo prosthetic crown preparation. ISRCTN registry: ISRCTN49594720.

The analogous intraoral judgement of the abutment preparation angle is almost impossible! At least avoid undercuts.

A total occlusal convergence (TOC) angle (ϕ) of 6 degrees is a typical crown preparation requirement. It has been shown that this is difficult to achieve clinically. The present study therefore aims to compare the ability of students to judge different steepnesses, including a -1-degree undercut of prepared canines and molars, under clinical conditions with different analog tools. The complete dentures of a patient were duplicated without denture teeth 16, 23, 33, and 46. For each of these gaps, six crown stumps were milled with ϕ/2 = -1, 3, 6, 9, 12, and 15 degrees, each of which was insertable using mini-magnets. A total of 144 dental students, 48 students each from the 1st, 6th, or 9th semester, estimated these angles intraorally with various aiding tools: In addition to basic dental instruments, they used a parallelometer mirror, an analog clock dial with a 6-degree visualization, and a scale of tooth stumps with ϕ/2 between -1 and 15 degrees. The widely demanded 3 degrees were hardly recognized, but assumed to be steeper or even undercut. In contrast, the -1-degree divergent stump walls were predominantly estimated as parallel-walled or slightly conical. With increasing taper, the stumps tended to be classified as steeper, ie, "better." The additional tools did not result in a general improvement of the estimation performance. Students from higher semesters did not achieve better results. The present authors question the objectivity of an exclusively visual assessment of crown stump taper. It appears that dental training should at least focus on avoiding undercuts as the minimal prerequisite for an accurate intraoral scanning procedure. Digital control of the preparation angle by an intraoral scan and immediate clinical implementation of these results could help to produce appropriate preparations.

Haptics Vs Typodonts for Crown Preparation in Undergraduate Dental Student Education.

This study aims to compare students' subjective perceptions and objective results by comparing two methods of crown preparation: typodonts and haptics. Fifty-four second-year students were given instructions on crown preparation for the upper right second premolar. First on typodonts and then with haptics. They were given five minutes to familiarize with the artificial environment and then thirty minutes for the actual preparation. Finally, they completed a questionnaire about their experience. Their preparations were objectively compared by measuring the angle of total occlusal convergence-TOC on the typodonts and with haptics. Students reported that haptics can enhance the learning process and that they would use them for skill training in the future. Overall, their experience was rated as positive. The TOC of teeth prepared with haptics was significantly higher than those prepared with typodonts, but all values were within the acceptable range. Although students did not prefer haptics to typodonts, haptics appear to be a powerful tool in the educational process because it can be a complementary option to traditional methods at the preclinical level.

A Clinical Comparison of Dental impression accuracy between One-step and Two-step Dual phase impression technique by using Polyvinyl Siloxane Impression Material.

Objective:: The objective was to assess the number of visible defects within impression made by two different techniques. Methodology: This was comparative cross-sectional study was conducted between June 2019 to December 2019 at out patient department of Institue of dentistry, LUMHS Jamshoro. Two impressions were made from 53 crown preparation by using one step and two step dual phase impression techniques. Totaling to 106 impressions. Polyvinyl Siloxane impression material was used with each technique. Evaluation of impressions were made for tears, voids and bubbles and impression were compute as acceptable (A or B) and unacceptable (C or D). Result: There was no significant difference seen in proportion of overall evaluation of two impression technique, as compared by using “Chi-square test”. Conclusion: Insignificant difference was seen b/w one step and two step dual phase impression techniques. Keywords: One step impression technique, two step dual phase impression technique, dimensional accuracy.

Comparison of digitally assessed quality of posterior crown preparations performed with and without previous practice on patient-specific three-dimensional-printed teeth models.

Three-dimensional (3D)-printing technology can provide customizable simulations, but its effects on patient care quality have not been well studied. This study aimed to assess the impact of practicing with patient-specific 3D-printed teeth models on the quality of patients' dental preparations performed by students transitioning to clinical training. Accordingly, the quality of posterior crown preparations was evaluated by objectively analyzing digital scans and grades in two groups: the study group, which practiced beforehand with patient-specific 3D-printed teeth models, and the control group, which did not practice with these models. All 78 fourth-year dental students who had just finished their fixed prosthodontics course at the simulation laboratory with training on phantom heads and without previous clinical experience in crown preparations were invited to participate in the study. Sixty-eight agreed to take part and were randomly divided into a study group that practiced crown preparations on 3D-printed models of their own patient's teeth and a control group that did not practice with 3D-printed models and started their clinical work straightforwardly after simulation training. Students completed validated perception questionnaires on self-confidence and clinical skills before and after the protocol, which were compared using a chi-squared test. Crown preparations performed on 3D-printed models and then on patients were digitally scanned and objectively graded by prepCheck software for critical parameters, such as undercuts, taper, and occlusion reduction. Non-parametric tests were used to compare preparations on 3D-printed models and on patients performed by the study group and those on patients made by the control group. Initially, both groups reported similar perceptions of self-confidence and clinical skills levels. The study group significantly improved both aspects after the protocol. Analysis of the scanned preparations demonstrated that the study group removed less tooth structure from actual patients than from the initial 3D-printed models. In contrast, the control group showed excess occlusal clearance in their patients compared to the study group. Practicing patient-specific 3D-printed teeth before performing procedures clinically appears to enhance preparation quality and minimize unnecessary tooth reduction in early clinical experiences.

Bonding Effectiveness of Saliva-Contaminated Monolithic Zirconia Ceramics Using Different Decontamination Protocols.

This research study investigated the effect of new decontamination protocols on the bonding capacity of saliva-contaminated monolithic zirconia (MZ) ceramics cemented with two different monomer-containing self-adhesive resin cements. Standardized tooth preparations (4 mm. axial height) were performed for eighty human maxillary premolars under constant water cooling system. Eighty monolithic zirconia crowns (Whitepeaks Supreme Monolith) (n = 8/10 groups) were manufactured by CAD-CAM. Specimens were kept in the artificial saliva at pH = 7.3 for 1 minute at 37°C except control groups. The specimens have not been prealumina blasted and grouped according to cleaning methods and resin cements: control groups (C) (no saliva contamination + GPDM + 4-META (N) (CN) and 10-MDP (M) containing resin cement (CM), alumina blasted (AL) + GPDM + 4-META (ALN) and 10-MDP containing resin cement (ALM), zirconium oxide containing universal cleaning agent (IC) applied + GPDM + 4-META (N) (ICN) and 10-MDP containing resin cement (ICM), pumice (P) applied + GPDM + 4-META (PN) and 10-MDP containing resin cement (PM), and air-water spray (AW) applied + GPDM + 4-META (AWN) and 10-MDP containing resin cement (AWM)). Monobond Plus was applied to all surfaces for 40 seconds before cementation. The thermal cycle was applied at 5,000 cycles after cementation. The crowns were tested in tensile mode at a speed of 1 mm/min. The mode of failure was recorded. SEM examinations were carried out at different magnifications. Data were analyzed using rank-based Kruskal-Wallis and Mann-Whitney tests. No significant differences were found between the surface treatments and between the two types of resin cements. Interaction effects between surface treatments and resin cements were found to be significant by two-way ANOVA analysis. ICM group resulted in significantly better bond strength results compared with CN. ICM was found to result in better bond strength results compared with PM. The combination of universal cleaning agent and 10-MDP containing resin cement had significantly the highest cementation bond strength values. The increasing order of mean tensile bond strength values of decontamination protocols was C < AW < P < AL < IC. The mean tensile bond strength of 10-MDP containing resin cement was slightly higher than GPDM + 4-META containing resin cement. Universal cleaning agents can be preferred as an efficient cleaning method with 10-MDP-containing cement after saliva contamination for better adhesive bond strength of 4 mm crown preparation height of monolithic zirconia ceramics.

Evaluating the effectiveness of a novel digital evaluation technology on dental preclinical crown preparation training.

To evaluate the assessment scores of a novel digital training program versus traditional training in dental preclinical crown preparation. Crown preparations in two consecutive preclinical training sessions were retrospectively collected and assigned to three groups: traditional group (TG), scanning group (SG), and digital evaluation group (DG). Students in the TG (n=20) were taught by conventional visual grading, while students in the SG (n=25) received three-dimensional feedback from digitally scanned preparations. All the SG students continued with supplementary digital evaluation and preparations were allocated into the DG (n=25). Comparison of total scores between groups was investigated using independent samples t-test and paired samples t-test. Mann‒Whitney U-test and Wilcoxon signed-rank test were used to statistically analyze the differences in subdividing categories. The level of significance was p<0.05. Questionnaires on the digital evaluation procedure were answered by students in DG. The results showed a significant improvement (p<0.01) in the total scores of DG than those of TG and SG, while there were no statistically significant differences between TG and SG. Scores of surface finish and undercut improved significantly in DG compared to TG and SG. The reduction scores of DG were significantly higher than those of SG. Students' feedback indicated a positive perspective on the implementation of the novel digital evaluation technology. These findings suggest that digital evaluation technology is useful for preclinical crown preparation training. Attention should also be paid to studying the optimal integration of digital dentistry into traditional dental curricula and its effects on students' learning curves.