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Orthodontics & Craniofacial Research Aug 2023Three-dimensional (3D) printing technology is a promising manufacturing technique for fabricating ceramic brackets. The aim of this research was to assess fundamental...
OBJECTIVES
Three-dimensional (3D) printing technology is a promising manufacturing technique for fabricating ceramic brackets. The aim of this research was to assess fundamental mechanical properties of in-office, 3D printed ceramic brackets.
MATERIALS AND METHODS
3D-printed zirconia brackets, commercially available polycrystalline alumina ceramic brackets (Clarity, 3 M St. Paul, MN) and 3D-printed customized polycrystalline alumina ceramic ones (LightForce™, Burlington, Massachusetts) were included in this study. Seven 3D printed zirconia brackets and equal number of ceramic ones from each manufacturer underwent metallographic grinding and polishing followed by Vickers indentation testing. Hardness (HV) and fracture toughness (K1c) were estimated by measuring impression average diagonal length and crack length, respectively. After descriptive statistics calculation, group differences were analysed with 1 Way ANOVA and Holm Sidak post hoc multiple comparison test at significance level α = .05.
RESULTS
Statistically significant differences were found among the materials tested with respect to hardness and fracture toughness. The 3D-printed zirconia proved to be less hard (1261 ± 39 vs 2000 ± 49 vs 1840 ± 38) but more resistant to crack propagation (K1c = 6.62 ± 0.61 vs 5.30 ± 0.48 vs 4.44 ± 0.30 MPa m ) than the alumina brackets (Clarity and Light Force respectivelty). Significant differences were observed between the 3D printed and the commercially available polycrystalline alumina ceramic brackets but to a lesser extent.
CONCLUSIONS
Under the limitations of this study, the 3D printed zirconia bracket tested is characterized by mechanical properties associated with advantageous orthodontic fixed appliances traits regarding clinically relevant parameters.
Topics: Hardness; Materials Testing; Ceramics; Aluminum Oxide; Surface Properties
PubMed: 36648375
DOI: 10.1111/ocr.12632 -
Quintessence International (Berlin,... Oct 2023Addressing a single-tooth gap in the anterior region, resulting from aplasia or trauma, poses both esthetic and functional challenges. This case report presents the...
Esthetic and functional rehabilitation of a patient with a bilateral cleft of lip, alveolar process, and palate with anterior all-ceramic cantilever resin-bonded fixed dental prostheses.
OBJECTIVES
Addressing a single-tooth gap in the anterior region, resulting from aplasia or trauma, poses both esthetic and functional challenges. This case report presents the restoration of a young adult with a cleft, exhibiting anterior hypoplasia and aplasia in the canine and incisor regions, using all-ceramic cantilever resin-bonded fixed dental prostheses.
METHOD AND MATERIALS
After verification of esthetic and functional considerations through a diagnostic wax-up and an intraoral mock-up, three anterior all-ceramic cantilever resin-bonded fixed dental prostheses made of veneered zirconium dioxide were planned in the region of the maxillary right lateral incisor and maxillary left canine. The impression was made with an intraoral scanner. The framework fit was evaluated. Glaze firing and full adhesive cementation under rubber dam followed.
RESULTS
The final restoration met the patients' expectations and restored facial esthetics and function.
CONCLUSIONS
All-ceramic cantilever resin-bonded fixed dental prostheses offer a promising minimally invasive therapeutic option for cleft patients.
Topics: Young Adult; Humans; Denture, Partial, Fixed, Resin-Bonded; Esthetics, Dental; Ceramics; Zirconium; Alveolar Process; Palate
PubMed: 37724999
DOI: 10.3290/j.qi.b4366813 -
The Journal of Prosthetic Dentistry Jul 2024Digital scanning is gradually replacing conventional impression making, but consensus on how tooth preparation influences the accuracy of intraoral scanning is lacking.
STATEMENT OF PROBLEM
Digital scanning is gradually replacing conventional impression making, but consensus on how tooth preparation influences the accuracy of intraoral scanning is lacking.
PURPOSE
The purpose of this in vitro study was to evaluate the effect of substrate material and abutment geometry on the accuracy of digital casts obtained by intraoral scanning.
MATERIAL AND METHODS
The height and total occlusal convergence (TOC) angle were measured in 5 different groups that contained 5 specimens of different materials: natural tooth, cobalt chromium alloy, titanium, zirconium dioxide ceramic, and resin. The specimens were scanned with an industrial scanner to obtain reference data. Each specimen was placed in a maxillary standard dentition model that was assembled in a head simulator. Each dentition model was scanned 10 times with an intraoral scanner (IOS) under operatory lighting conditions to acquire intraoral scanning files for each specimen. All data were imported into a metrology software program and processed. A total of 10 trueness deviations, the mean superimposition results between IOS scanning data and reference data, and precision deviations, the mean superimposition results between IOS scanning data in pairs, were recorded. Two-way analysis of variance (ANOVA) and Tukey multiple comparison test were used to analyze the accuracy of intraoral scanning in relation to the height or TOC angle of the abutment (α=.05). The total means of each substrate material were compared with the Kruskal-Wallis test and Dunn test for multiple comparisons.
RESULTS
The accuracy of scanning images was related to material and abutment geometry (P<.05). Bias was larger as abutment height increased with most substrates. Larger TOC angles increased the accuracy of the digital scans. The trueness deviation of translucent materials and the precision deviation of reflective materials were generally larger.
CONCLUSIONS
Substrate material and abutment geometry influence the accuracy of intraoral scanning. The accuracy of IOS generally tended to improve with decreasing height and increasing TOC angle and was affected by different substrates.
Topics: Dental Abutments; Humans; In Vitro Techniques; Zirconium; Computer-Aided Design; Titanium; Dental Materials; Dental Impression Technique; Models, Dental
PubMed: 38653689
DOI: 10.1016/j.prosdent.2024.04.001 -
Clinical Oral Implants Research Oct 2023To assess accuracy of intraoral optical scanning (IOS) and stereophotogrammetry (SPG), complete-arch digital implant impressions in vivo.
OBJECTIVES
To assess accuracy of intraoral optical scanning (IOS) and stereophotogrammetry (SPG), complete-arch digital implant impressions in vivo.
MATERIALS AND METHODS
Consecutive patients needing implant-supported screw-retained zirconia complete-arch fixed-dental prostheses (ISZ-FDP) were recruited. For each patient, three impressions were taken: IOS, SPG (tests), and open-tray plaster (reference). Linear (ΔX, ΔY, and ΔZ), three-dimensional (ΔEUC), and angular deviations (ΔANGLE) were evaluated and stratified according to scanning technology for each implant. Potential effects of impression device (IOS and SPG), arch (maxilla and mandible), and implant number (4 and 6) were evaluated through multivariable analysis. Significance level was set at .05.
RESULTS
A total of 11 complete arches (5 maxillae, 6 mandibles) in 11 patients were rehabilitated with ISZ-FDPs supported by 4 (n = 8) and 6 implants (n = 3). A total of 50 implants and 100 implant positions were captured by two investigated devices and compared to respective reference (mean ΔEUC IOS 137.2, SPG 87.6 μm; mean ΔANGLE 0.79, 0.38°). Differences between measurements (SPG-IOS) were computed for each implant, with negative values indicating better SPG accuracy. Significant mean ΔEUC difference of -49.60 μm (p = .0143; SD 138.15) and mean ΔANGLE difference of -0.40° (p < .0001; SD 0.65) were observed in favor of SPG. Multivariable analysis showed significant effect on ΔEUC (p = .0162) and ΔANGLE (p = .0001) only for impression devices, with SPG performing better.
CONCLUSIONS
SPG experienced significantly higher linear and angular accuracy. No effect of type of arch or implant number was detected. Higher extreme deviations were experienced for IOS. SPG can be feasible for complete-arch digital impressions with caution, and rigid prototype try-in is recommended before screw-retained prosthesis manufacturing.
PubMed: 37485737
DOI: 10.1111/clr.14141 -
European Journal of Dental Education :... May 2024In fixed prosthodontics, simulators are essential to students for a progressive transition from preclinical to clinical condition. With the 3D printing technology, we...
INTRODUCTION
In fixed prosthodontics, simulators are essential to students for a progressive transition from preclinical to clinical condition. With the 3D printing technology, we developed resin bars allowing students to better visualise by motor chunking technique. Main objectives of this work were to describe this teaching methodology used in preclinic among different promotions of second, third and fourth dental years and to evaluate students' feedback.
MATERIALS AND METHODS
Two hundred seventy resin strips were digitally designed and printed in resin. All participants from second, third and fourth had to fulfil a User Experience Questionnaire (UEQ) after the preclinical work. The scales of this questionnaire covered the complete impression of the user experience. Both classical aspects of usability (efficiency, insight and reliability) and aspects of user experience (originality, stimulation) were measured.
RESULTS
For the second dental years, 'Attractiveness', 'Stimulation' and 'Novelty' were considered 'Excellent'. For the third dental year, novelty average was considered as 'Excellent'. For the fourth dental year, 'novelty' was considered as 'Good'.
DISCUSSION
The resin plates used in this study are original and stimulating for the students, especially for the second-year dental students who found the exercises useful for their learning. This method can also be used by creating scenarios close to the clinical situations encountered in dentistry departments (more dilapidated teeth, preparation of inlays, post and core, etc.). This 3D printed simulation model is not intended to replace the Frasaco® models but is a complement to the learning process.
Topics: Humans; Students, Dental; Prosthodontics; Motor Skills; Reproducibility of Results; Education, Dental; Printing, Three-Dimensional; Personal Satisfaction
PubMed: 37908156
DOI: 10.1111/eje.12961 -
The Journal of Prosthetic Dentistry Oct 2023Although intraoral scanners (IOSs) are popular, few studies have evaluated the accuracy of digital mounting by using IOSs.
STATEMENT OF PROBLEM
Although intraoral scanners (IOSs) are popular, few studies have evaluated the accuracy of digital mounting by using IOSs.
PURPOSE
The purpose of this in vitro study was to compare the accuracy of digital mounting by using 2 IOSs and 2 occlusal scanning methods.
MATERIAL AND METHODS
Fourteen Ø5-mm zirconia balls were attached approximately 5 mm apical to the free gingival margin of both second molars, second premolars, and canines and between the central incisors in maxillary and mandibular epoxy casts. A polyetheretherketone hexagonal cube with a 10-mm-long edge was attached to the buccal side of the missing mandibular right first molar area, and the cube was used to set a part coordinate system. Two IOSs (TRIOS 3, Primescan) were used to assess the intra-arch and interarch accuracies. For intra-arch assessment, each IOS was used to digitally scan the mandibular epoxy cast 15 times and fabricate 15 datasets. The deviation of each zirconia ball centroid was statistically compared between the IOSs. For interarch assessment, each IOS was used to digitally scan the maxillary and mandibular epoxy casts, and the data were digitally mounted by using a single anterior occlusal scan (A) or bilateral posterior occlusal scan (P). Both occlusal scans were performed 15 times; therefore, 4 groups (15 datasets per group) of mounted digital datasets were assigned. The deviation of each maxillary zirconia ball centroid, as well as the interarch distance between the corresponding maxillary and mandibular zirconia ball centroids, were compared among the 4 groups. For statistical analysis, the Mann-Whitney U test and Kruskal-Wallis test with Bonferroni correction were used (α=.05).
RESULTS
Primescan had less deviation than TRIOS 3 in the complete arch scan. When the zirconia balls were close to the origin, the bilateral posterior occlusal scan produced less deviation of their centroids. Primescan produced decreased interarch distance in the anterior and posterior dentition, while TRIOS 3 produced increased interarch distance in the anterior dentition and decreased interarch distance in the posterior dentition.
CONCLUSIONS
A significant difference was noted in intra-arch accuracy between the IOSs, and the difference influenced the digital mounting accuracy. The type of occlusal scan and IOS significantly influenced the accuracy of digital mounting. Both IOSs produced decreased interarch distances in the second molar area.
Topics: Imaging, Three-Dimensional; Dental Impression Technique; Models, Dental; Computer-Aided Design; Dental Arch
PubMed: 37633731
DOI: 10.1016/j.prosdent.2023.07.028 -
Advances in Clinical and Experimental... Jun 2024The development of malocclusion is related to various factor, many of which are still not fully explained. The steroid hormone, 1,25-dihydroxyvitamin D3, has pleiotropic... (Observational Study)
Observational Study
BACKGROUND
The development of malocclusion is related to various factor, many of which are still not fully explained. The steroid hormone, 1,25-dihydroxyvitamin D3, has pleiotropic effects. It plays a key role in skeletal metabolism and the control of cell repair by attaching to the nuclear vitamin D steroid receptor (VDR). This vitamin affects bone turnover through the processes of bone tissue formation and resorption via its action on cells of the osteoblastic and osteoclastic lineage, exerts a modulating effect on the immune system, and is involved in the regulation of cell proliferation and differentiation. The role of vitamin D3 (VD3) and its receptor polymorphisms is a rarely studied topic in dentistry. Due to the proven influence on bone turnover processes and immune responses, the main research topic is its relation to periodontal diseases, but so far, its role in the formation and development of malocclusions has not been assessed.
OBJECTIVES
This study aimed to assess the association of selected VDR polymorphisms: Cdx2 (rs11658820), TaqI (rs7975232), BsmI (rs1544410), ApaI (rs7975232), and FokI (rs2228570) with the development of malocclusions.
MATERIAL AND METHODS
A prospective observational study was performed. The examination consisted of a medical interview, intraand extraoral orthodontic diagnosis, alginate impression, cone beam computed tomography (CBCT), and venous blood sample to obtain genomic DNA and assess VDR polymorphisms.
RESULTS
The rs11658820 polymorphism causes an almost 4-fold increase in the probability of the presence of a malocclusion. GT and TT genotypes of rs7975232 are also associated with a similar risk - almost 6 and almost 5 times higher, respectively. In turn, the effect of the rs2228570-AG and GG genotype polymorphisms on the occurrence of transversal anomalies was demonstrated (odds ratio (OR) = 8.46 and OR = 6.92, respectively).
CONCLUSIONS
The association of individual polymorphisms with specific malocclusions should be carefully assessed, especially since some trends have been indicated.
Topics: Humans; Receptors, Calcitriol; Malocclusion; Genetic Predisposition to Disease; Female; Male; Polymorphism, Single Nucleotide; Prospective Studies; Adult; Young Adult; Adolescent; Polymorphism, Genetic
PubMed: 38353502
DOI: 10.17219/acem/169977 -
International Journal of Implant... Dec 2023A high transfer accuracy of the intraoral implant position to a model is required, to manufacture implant-supported restorations. However, clinically relevant deviations...
PURPOSE
A high transfer accuracy of the intraoral implant position to a model is required, to manufacture implant-supported restorations. However, clinically relevant deviations persist between the intraoral implant position and the model obtained, even for the benchmark conventional custom implant impressions with polyether. Thus, new approaches using 3-D printed impression trays may increase the transfer accuracy of implant impressions. The ability to adjust parameters such as the thickness of the layers and the influence of the openings in the impression tray could potentially affect accuracy.
METHODS
Four different types of impression trays (n = 10 for each group) for the conventional impression technique were investigated: conventional custom impression tray, customized foil tray, chairside 3-D printed impression tray with the SHERA system, and the Primeprint system using an implant master model with four implants in the posterior region and a reference cube. After plaster model casting, all models were measured using a coordinate measuring machine, and the deviation from the reference dataset was determined. A statistical ANOVA analysis was performed (p < 0.05).
RESULTS
Chairside 3-D printed impression trays showed the best results, followed by conventional custom impression trays. Implant impressions obtained using a customized foil tray exhibited the lowest accuracy. Statistically significant differences were observed between 3-D printed impression trays and conventional custom impression and customized foil trays (p < 0.05). Whereas, the implant position did not have any significant influence on accuracy (p > 0.05).
CONCLUSIONS
Chairside 3-D printed impression trays significantly increase the transfer accuracy for implant impression taking.
Topics: Dental Impression Materials; Dental Implants; Dental Impression Technique; Models, Dental; Research Design
PubMed: 38052992
DOI: 10.1186/s40729-023-00516-9 -
Heliyon Jan 2024The aim of this study is to evaluate the understanding of the management of methods and practices of disinfection of dental impressions applied by general dentists and...
PURPOSE
The aim of this study is to evaluate the understanding of the management of methods and practices of disinfection of dental impressions applied by general dentists and specialists in oral rehabilitation, post SARS-COV-2 pandemic.
INTRODUCTION
The oral cavity has a favorable environment for the growth and multiplication of bacteria and viruses, serving as the gateway to viruses such as SARS CoV-2 virus. Given that patients may be hosts of this infectious disease, stricter biosecurity measures in dental offices and a better understanding of the disinfection processes of dental impressions should be considered in addition to avoiding cross-infections, which are very common in our work environment.
MATERIALS AND METHODS
Descriptive, analytical, survey with the topic "Methods and practices of disinfection of dental impressions" that was composed of 14 questions based in OHPD (Oral Health Preventive Dentistry), n = 452 respondents who met the following inclusion criteria: general practice dentists from Ecuador who actively take dental impressions, specialists in oral rehabilitation with 5 years of experience, surveys with information of complete items, n = 270 professionals; n = 192 general dentists, dental hygienist and n = 78 oral rehabilitation specialists.
RESULTS
n = 270 professionals evaluated, with a mean of p = 0.0. At 426 responses with a p value of <0.05, 30.4 % of responses indicated ignorance in the management of dental impressions, with a standard deviation of 2.744, with significant differences between professions (p = 0.035) and higher average knowledge of sample management within specialist dentists, (Chi p = 0.410 p > 0.05).
CONCLUSION
The understanding of the management of dental impressions among general dentists and specialists in oral rehabilitation is limited.
PubMed: 38169934
DOI: 10.1016/j.heliyon.2023.e23280 -
International Journal of Dentistry 2023This study aimed to evaluate the effects of aluminum chloride based hemostatic agents on the surface detail reproduction and dimension stability. Three impression...
This study aimed to evaluate the effects of aluminum chloride based hemostatic agents on the surface detail reproduction and dimension stability. Three impression materials were investigated after contaminated with three commercial astringents with different concentration of aluminum chloride. The specimens from three impression materials were fabricated with a stainless-steel mold that followed the American Dental Association specification no.19. The mold was preliminarily contaminated with three hemostatic agents racestyptine, Dryz, and Expasyl™-and 80 specimens from each impression material-polyvinylsiloxane (PVS), polyether, and polyvinylsiloxane ether (PVSE), were fabricated and subjected to each astringent. The surface detail reproduction was examined using a stereomicroscope at 4x magnification, and the dimensional stability was analyzed at 24 hr with a measuring microscope. The surface detail data were statistically analyzed with Fisher's test at a significance level of 0.05. The dimensional stability data were analyzed using two-way ANOVA and Tukey's test at a significance level of 0.05. Aluminum chloride hemostatic agents can affect the surface detail reproduction of impression materials differently ( < 0.05). Thus, the first null hypothesis was rejected. PVS showed the highest percentage of satisfactory surface detail regardless of the hemostatic agent used in this study. PVSE showed a reduced percentage of satisfactory surface detail when the concentration of aluminum chloride was high. The three hemostatic agents affected the dimensional stability of each material differently ( < 0.05). Therefore, the second null hypothesis was also rejected.
PubMed: 37547813
DOI: 10.1155/2023/6660721