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1.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 56(6): 570-575, 2021 Jun 09.
Artículo en Chino | MEDLINE | ID: mdl-34098673

RESUMEN

Objective: To comparatively evaluate the scan time and the accuracy of maxillary full-arch scans using four intraoral scanners (IOS) on conditions of the intraoral head-simulator and the hand-held model, and to evaluate the influence of different scanning conditions on digital scan. Methods: A upper dental arch model with melamine-formaldehyde resin teeth and silica gel gingiva that could be fixed on a head simulator was scanned with an optical scanner (ATOS Core) in order to obtain the standard tessellation language dataset as reference. Intraoral scans were performed on the model fixed on the head simulator by three researchers with four IOS [A: TRIOS 3; B: CS 3600; C: CEREC Omnicam; D: iTero]. For each scanner and each researcher, six scans were performed, to obtain the datasets as the head simulator group. And another six scans with each of the four intraoral scanners were performed by each researcher on the hand-held model to obtain the STL datasets as the hand-held group. The scan time were recorded for each scan. In the Geomagic Wrap software, the digital models were trimmed with only the teeth information retained and supreimposed by best fit alignment function and compared to obtain the root mean square (RMS) values of the discrepancies by three-dimensional compare function. The test datasets of each group were compared with the reference dataset for trueness. The six test scanning datasets with the same scanner of the same researcher were cross compared for precision. Mann Whitney U test was used to statistically analyze the difference values of the scan time, trueness and precision of the same intraoral scanner between head simulator group and hand-held group. Results: Compared to the hand-held group, the scan time of A [142(82) s] and D [119(52) s], which two IOS both with handle, were longer in head simulator group [A: 98(28) s; D: 85(22) s] (P<0.01). However there were no significant differences between the two groups for scan time of IOS B and C (P>0.05). For full-arch scan accuracy (trueness and precision), there were no significant differences between the two groups of IOS A and B (P>0.05), while the trueness of C (P<0.05) and the precision of D (P<0.01) were better in head simulator group [C: 112(38) µm; D: 43(13) µm] compared to hand-held group [C: 135(47) µm; D: 53(18) µm]. However, there were no significant differences for the precision of C (P>0.05) and the trueness of D (P>0.05). Conclusions: The scan time and the accuracy of full-arch digital scans with different IOS may be effected by the scan conditions. For in vitro study of intraoral scanning, head-simulator can simulate the intraoral environment of the real patient to some extent. Meanwhile, the position of the dentist and the patient, and also the limited intraoral space during intraoral scanning are also simulated.


Asunto(s)
Técnica de Impresión Dental , Modelos Dentales , Diseño Asistido por Computadora , Arco Dental , Humanos , Imagenología Tridimensional
2.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 56(6): 576-580, 2021 Jun 09.
Artículo en Chino | MEDLINE | ID: mdl-34098674

RESUMEN

To explore the technical process and the therapeutic effect of using sequential surgical guide with independent intellectual property rights assisting immediate implantation and restoration of the full arch, with the support from the periodontal splint for mobile supporting teeth, patients with severe periodontitis who planned to undergo immediate full arch implantation were recruited from August 2019 to December 2020 at the Department of Prosthodontics, Department of Periodontology, Department of Implantology and First Clinical Division, Peking University School and Hospital of Stomatology. Through the procedure of collecting preoperative maxillofacial data, making systematic diagnostic design, making periodontal splints fixation, producing surgical guide, and carrying out guided surgery for full arch immediate implantation, eight cases were included. By registering the postoperative cone-beam CT (CBCT) with the preoperative data, the difference between the actual three-dimensional position of the implants and the virtual design was observed, and the accuracy of the implant placement position guided by the sequential guide was statistically analyzed using SPSS 25.0 software. Analysis indicators include coronal and apical global displacement, coronal horizontal and vertical displacement, apical horizontal and vertical displacement, and angular deviation. Results revealed that the 8 patients [2 males and 6 females, aged (49.0±9.3) years (38-65 years)] of recruited cases included 7 cases of maxilla and 1 cases of mandible. A total of 48 implants, of which 44 implants were placed upright and 4 were placed tilted, 16 implants in the anterior region and 32 implants in the posterior region. No guide plate fracture or damage to important anatomical structures were reported. The overall displacement at the coronal point [(0.83±0.48) mm] and the global displacement at the apical point [(1.36±0.57) mm] were within the clinically acceptable safety range, and the horizontal displacement and vertical displacement at the coronal point, horizontal displacement and vertical displacement at the apical point, and the angle deviation of implants axial have no statistic significant difference in the anterior and posterior region (P>0.05). Periodontal splints combined with sequential surgical guides to assist patients with severe periodontitis for immediate full arch implantation and immediate restoration can expand the indications of guide assisted implant surgery. It meets the safety requirements in clinical applications.


Asunto(s)
Implantes Dentales , Periodontitis , Cirugía Asistida por Computador , Diseño Asistido por Computadora , Tomografía Computarizada de Haz Cónico , Implantación Dental Endoósea , Femenino , Humanos , Imagenología Tridimensional , Masculino , Periodontitis/cirugía
3.
Int J Oral Maxillofac Implants ; 36(3): 442-449, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34115056

RESUMEN

PURPOSE: To investigate the effect of implant angulation, non-free-end partial edentulism, and number of scan bodies on the accuracy of digital impressions of multiple implants in partially edentulous arches. MATERIALS AND METHODS: Four reference models of partially edentulous mandibles with implants (RM1, RM2, RM3, and RM4) representing different intraoral situations were each scanned 10 times by an intraoral scanner. Reference scans were obtained by a laboratory scanner. Test scans were compared with reference scans to obtain the distance deviations (Δd) and angular deviations (Δθ) between scan bodies for trueness assessment. Differences among the repeated test scans of each model were measured and recorded as Δdp and Δθp for precision assessment. The Student t test (α = .05) was used to compare Δd, Δθ, Δdp, and Δθp of different reference models, including RM2 vs RM1 (effect of non-free-end partial edentulism), RM3 vs RM1 (effect of implant angulation), and RM4 vs RM1 (effect of number of scan bodies). RESULTS: The implant with 17-degree angulation in RM3 showed significantly lower Δd, Δθ, and Δθp compared with the parallel implant in RM1 (Δd: P = .0382, Δθ: P = .0267, Δθp: P = .0417). The RM2 of non-free-end partial edentulism had lower distance and angular deviations than RM1, but without a significant difference. The number of scan bodies had no significant effect on the Δd, Δθ, Δdp, and Δθp of RM4 and RM1. CONCLUSION: Angulated implants showed better accuracy of digital impressions in partially edentulous arches compared with parallel implants. Non-free-end partial edentulism was attributed to improved accuracy, while the number of scan bodies showed no effect.


Asunto(s)
Implantes Dentales , Boca Edéntula , Diseño Asistido por Computadora , Técnica de Impresión Dental , Modelos Dentales , Humanos , Imagenología Tridimensional
4.
Int J Oral Maxillofac Implants ; 36(3): 485-491, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34115062

RESUMEN

PURPOSE: To evaluate the factors that could influence the fracture resistance of implant-supported posterior monolithic zirconia crowns. MATERIALS AND METHODS: Sixty zirconia molar crowns with three different occlusal thicknesses of 0.5, 1.0, and 1.5 mm (20 samples per group) were prepared for implant abutments using a CAD/CAM system. In each group, 10 crowns were luted on the abutment with resin cement (Panavia F), and the other 10 crowns were luted with resin-modified glass-ionomer cement (Ketac Cem Plus). Dynamic loading (1.2 × 106 cycles; 70 N) and thermal cycling were applied to the samples using a chewing simulator before evaluating their fracture resistance with a universal testing machine and examining their fracture type using a stereomicroscope. One-way analysis of variance (ANOVA), the Duncan test, and two-way ANOVA were used for data evaluation (α = .05). RESULTS: The occlusal thickness (P < .001) and cement type (P < .01) affected the fracture load of the monolithic zirconia crowns. The highest fracture resistance was found in 1.5-mm-thick crowns luted with resin cement (4,212 ± 501 N), and the lowest fracture resistance was found in 0.5-mm and 1-mmthick crowns luted with resin-modified glass-ionomer cement (1,198 ± 116 N and 1,197 ± 66 N). A significant difference was not found in the mean maximum fracture load between the 1.5-mm-thick crowns cemented with resin cement and glass-ionomer resin cement. CONCLUSION: Both the occlusal thickness and cement type remarkably affected the fracture resistance of the crowns, but occlusal thickness was more significant. Implant-supported posterior zirconia crowns can withstand physiologic occlusal forces even with a thickness as low as 0.5 mm. Resin luting cement is recommended for implant-supported posterior zirconia crowns with reduced occlusal thickness.


Asunto(s)
Implantes Dentales , Porcelana Dental , Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Análisis del Estrés Dental , Cementos de Ionómero Vitreo , Ensayo de Materiales , Cementos de Resina , Circonio
5.
Niger J Clin Pract ; 24(6): 828-832, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-34121729

RESUMEN

Background: Temporary stage in crowns and bridgework plays an important role in the success and failure of the final restorations. Lack of marginal seal of the temporary restorations can lead to further complications. Recently, digital dentistry has been improved in terms of marginal integrity. Aims: The aim of this study was to evaluate and compare the marginal leakage between CAD/CAM and conventionally made Polymethyl methacrylate (PMMA) interim crowns cemented with different temporary luting cements. Materials and Methods: Sixty resin dies of a maxillary right first premolar were prepared according to the protocol of the tooth preparation for all-ceramic crown. Interim crowns were then fabricated and assigned to two main groups according to the fabrication technique (CAD/CAM technique and conventional technique). Furthermore, the samples were sub-grouped (n = 10) according to the type of the luting cements: Zinc oxide eugenol (RelyX temp E), Zinc oxide non-eugenol (RelyX temp NE), and Zinc polycarboxylate cement (pentron). The specimens were then subjected to thermocycling at 5°C and 55°CC for 30 sec and transfer time of 15 seconds for 1500 cycles. After that, the specimens were immersed in a 2% methylene blue solution for 24 hours. The cemented specimens were sectioned buccolingually and the amount of marginal leakage was evaluated under digital microscope at magnification 50x. The scores of dye penetration were recorded and analyzed using one-way ANOVA at P < 0.05 for all tests. Results: For the fabrication technique, CAD/CAM-made interim crowns had significantly better performance in terms of lower microleakage in comparison to conventionally built interim crowns (P < 0.001). Overall, Zinc Oxide non-eugenol also showed significantly least microleakage as a luting cement then Zinc Oxide Eugenol and the most microleakage was found with Zinc Polycarboxylate regardless of the fabrication method. Conclusion: Interim crowns fabricated by CAD-CAM system are better suited for temporization. Zinc-oxide non-eugenol cements showed the least amount of microleakage in both types of crown.


Asunto(s)
Diseño Asistido por Computadora , Coronas , Cementación , Cementos Dentales , Cementos de Ionómero Vitreo , Ensayo de Materiales , Cementos de Resina , Preparación del Diente
6.
Int J Mol Sci ; 22(11)2021 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-34067261

RESUMEN

The present in vivo study determined the microbiological counts of the gingival crevicular fluid (GCF) among patients with fixed dental prostheses fabricated using three different techniques. A total of 129 subjects were divided into three study groups: first, cobalt-chrome-based, metal-ceramic prostheses fabricated by the conventional method (MC, n = 35); the second group consisted of cobalt-chrome-based, metal-ceramic prostheses fabricated by the computer-aided design and computer-aided manufacturing (CAD/CAM) technique (CC-MC, n = 35); the third group comprised zirconia-based ceramic prostheses fabricated using the CAD/CAM technique (CC-Zr, n = 35). The control consisted of 24 patients using prostheses fabricated with either MC, CC-MC, or CC-Zr. The GCF was obtained from the subjects before treatment, and 6 and 12 months after the prosthetic treatment. Bacteriological and bacterioscopic analysis of the GCF was performed to analyze the patients' GCF. The data were analyzed using SPSS V20 (IBM Company, Chicago, IL, USA). The number of microorganisms of the gingival crevicular fluid in all groups at 12 months of prosthetic treatment reduced dramatically compared with the data obtained before prosthetic treatment. Inflammatory processes in the periodontium occurred slowly in the case of zirconium oxide-based ceramic constructions due to their biocompatibility with the mucous membranes and tissues of the oral cavity as well as a reduced risk of dental biofilm formation. This should be considered by dentists and prosthodontists when choosing restoration materials for subjects with periodontal pathology.


Asunto(s)
Prótesis Dental/microbiología , Líquido del Surco Gingival/microbiología , Diente/microbiología , Adolescente , Adulto , Biopelículas/efectos de los fármacos , Cerámica/uso terapéutico , Diseño Asistido por Computadora , Femenino , Humanos , Masculino , Persona de Mediana Edad , Periodoncio/microbiología , Adulto Joven , Circonio/uso terapéutico
7.
Int J Comput Dent ; 24(2): 117-123, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085497

RESUMEN

AIM: A technique for merging digital intraoral and CBCT scans for implant-supported complete-arch fixed dental prostheses (FDPs) is described. The aim is to improve the dimensional accuracy of intraoral scans in edentulous arches. MATERIALS AND METHOD: Two files are recorded: an intraoral scan and a CBCT scan, both obtained with scan bodies connected to the implants in the same position. The intraoral scan is then divided into several fragments and realigned, taking as reference the position of the implants recorded in the CBCT file. RESULTS: An improved intraoral digital model with corrected implant positions appropriate for complete-arch implant FDPs is generated. CONCLUSION: The methodology proposed can minimize possible intraoral scanning error and deliver more reliable digital impressions for implant-supported complete-arch FDPs.


Asunto(s)
Implantes Dentales , Tomografía Computarizada de Haz Cónico Espiral , Diseño Asistido por Computadora , Técnica de Impresión Dental , Modelos Dentales , Humanos , Imagenología Tridimensional
8.
Int J Comput Dent ; 24(2): 133-145, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085499

RESUMEN

AIM: The positional accuracy of bracket placement planned through tooth setup vs actual placement was evaluated by means of conventional thermoplastic indirect bonding trays and customized 3D-printed indirect bonding trays. MATERIALS AND METHODS: A total of 280 bracket positions placed on the crowns of 10 dental plaster models were evaluated. The manual setup method and a thermoplastic indirect bonding tray were used for the manual group. For the CAD/CAM group, the bracket was positioned using a digital setup and a corresponding 3D-printed tray. The positional accuracy of the bracket placement on the duplicated gypsum model using the trays was evaluated by means of 3D software. Six errors of bracket position (height, depth, mesiodistal, torque, rotation, and tip errors), including linear and angular errors, were measured. Differences in variables were compared across subgroups using the independent t test or the Mann-Whitney U test. RESULTS: Only the height error differed significantly (P < 0.05) between groups (manual: 0.2 mm; CAD/CAM: 0.12 mm). For both incisors and molars, the manual group showed significantly greater height errors than the CAD/CAM group (P < 0.05). The analysis of variance of the position error to the whole bracket showed statistically significant differences between tooth positions, linear measurements, and angular measurements (P < 0.05). CONCLUSION: A 3D-printed indirect bonding tray showed accuracy similar to that of conventional methods for bracket placement, with slightly greater bracket height accuracy. Further studies should strive to improve accuracy in terms of tooth positions.


Asunto(s)
Recubrimiento Dental Adhesivo , Soportes Ortodóncicos , Diseño Asistido por Computadora , Modelos Dentales , Humanos , Impresión Tridimensional
9.
Int J Comput Dent ; 24(2): 147-155, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085500

RESUMEN

BACKGROUND: The esthetic outcome of a dental restoration largely depends on the translucency of the materials used, especially for monolithic restorations. Research has been published reporting a correlation between translucency and material thickness. However, no mathematical formula has been described yet. The aim of the present study was to determine the mathematical relationship between material thickness and translucency of three dental ceramic materials. MATERIAL AND METHODS: Three representative all-ceramic materials were taken out of the group of silicate ceramics (IPS Empress CAD LT), lithium X-silicate ceramics (IPS e.max CAD LT), and oxide ceramics (Lava Plus HT). Sixty specimens with five different thicknesses (0.4, 0.7, 1.0, 1.3, and 1.6 mm; N = 60, n = 12) were produced out of each ceramic (N = 180). A spectrophotometer was used to measure the transmittance coefficient tc[%] for each wavelength within the visible light spectrum, and the total light transmittance (T%) was calculated for each specimen. Linear, exponential, and logarithmic regression curves were fitted to the results. RESULTS: The logarithmic regression curves exhibited the best correlation (R2; IPS Empress CAD LT, R2 = 0.996; IPS e.max CAD LT, R2 = 0.987; Lava Plus HT, R2 = 0.907) to the transmittance values. CONCLUSION: Within the limitations of the present study, the transmittance behavior of silicate ceramics, lithium-X-silicate ceramics, and oxide ceramics can be described by a logarithmic equation. The findings of this study therefore suggest that the optical behavior might be calculable by a mathematical approach.


Asunto(s)
Porcelana Dental , Estética Dental , Cerámica , Diseño Asistido por Computadora , Humanos , Luz , Ensayo de Materiales , Espectrofotometría , Propiedades de Superficie
10.
Int J Comput Dent ; 24(2): 157-164, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085501

RESUMEN

AIM: Dental research involves variations between actual and reference datasets of master models to determine the metric accuracy through transfer accuracy tests. Various methods of measurement are used to analyze the results, which are often subjected to direct comparisons. Hence, the aim of the present study was to analyze the influence and effect on results of different methods of digital data analysis, being coordinate-based analysis (CBA) and best-fit superimposition analysis. MATERIALS AND METHODS: A model with four implants and a reference cuboid was digitized through computed tomography (CT), which served as the master model. Ten implant impressions were made using a Trios (3Shape) intraoral scanner, and three different scan bodies (nt-trading, Kulzer, and Medentika) were used. The deviations between the master model and the digital impressions were analyzed using CBA and best-fit superimposition analysis. Statistical analysis was performed using SPSS 25. RESULTS: The deviations in the CBA and best-fit superimposition analysis ranged from 0.088 ± 0.012 mm (mean ± SE; Medentika, 14) to 0.199 ± 0.021 mm (Kulzer, 26), and from 0.042 ± 0.010 mm (Medentika, 16) to 0.074 ± 0.006 mm (Kulzer, 16), respectively. Significant differences were observed between the implant positions in the CBA and the digital measurements at each implant position, whereas the best-fit analysis showed no significant difference between the scan bodies and implant positions. CONCLUSION: CBA displays an advantage over best-fit superimposition analysis in the detection of possible influencing factors for primarily scientific purposes. However, a global analysis and visualization of angles and torsions is difficult, for which a best-fit evaluation is needed. However, a best-fit analysis better represents the clinical try-in. It is associated with the risk that possible disturbing factors and resulting errors might be leveled out and their identification camouflaged.


Asunto(s)
Implantes Dentales , Técnica de Impresión Dental , Diseño Asistido por Computadora , Análisis de Datos , Materiales de Impresión Dental , Modelos Dentales , Humanos , Imagenología Tridimensional
11.
Int J Comput Dent ; 24(2): 165-179, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085502

RESUMEN

Computer-assisted implant surgery is one of the techniques that has gained much popularity over the past years. The amount of information that can be managed in a virtual environment allows for a faster, safer, and more precise implant placement. In certain cases, an appropriate implant-supported rehabilitation is accompanied by the need for complementary surgical procedures. The present technique report describes a clinical situation in which a bone reduction template and a stackable implant placement guide were digitally designed and 3D printed for a simultaneous ridge ostectomy and computer-assisted implant placement.


Asunto(s)
Implantes Dentales , Cirugía Asistida por Computador , Diseño Asistido por Computadora , Computadores , Implantación Dental Endoósea , Prótesis Dental de Soporte Implantado , Humanos
12.
Int J Comput Dent ; 24(2): 181-194, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085503

RESUMEN

AIM: The present clinical case reports on the workflow of a multidisciplinary treatment including both orthodontic and esthetic procedures for the rehabilitation of a young patient with severe wear in the anterior area of both the maxillary and mandibular arches due to malocclusion. The described workflow comprises a digital step-by-step process that involves 3D printing, intraoral scanners, and CAD/CAM milling systems. RESULTS: Accurate diagnostic and treatment planning were paramount when different specialties needed to combine and work together. For that purpose, different digital procedures helped to improve the predictability and the dynamic of the orthodontic and restorative treatments. CONCLUSION: The present multidisciplinary clinical case was executed with a digital approach that assisted to speed things up and achieve a predictable treatment option.


Asunto(s)
Coronas con Frente Estético , Diente , Diseño Asistido por Computadora , Estética Dental , Humanos , Maxilar
13.
Int J Comput Dent ; 24(2): 195-205, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085504

RESUMEN

AIM: The aim of the present study was to compare the marginal gap of teeth restored with crowns using six different CAD/CAM materials with two different milling units. MATERIALS AND METHODS: Ten mandibular molar teeth were collected after surgical extractions and prepared with two different diamond-coated instruments to receive full veneer crowns. The teeth were optically scanned, designed in CAD/CAM software, and milled in two different milling units. The marginal gap was measured using an optical microscope at 200x magnification. The restricted maximum likelihood (REML) method was used to estimate unknown parameters, and the statistical calculation was performed using R software. RESULTS: The model used to answer the primary study question involved a significant (P < 0.001) instrument versus material interaction. No other interaction was statistically significant (P = 0.146). Finally, significant within-crown heteroscedasticity was found (P < 0.001) for the two different diamond-coated instruments and was taken into account in the model used. CONCLUSIONS: The marginal gaps achieved by the crowns across all groups were within a clinically acceptable range.


Asunto(s)
Adaptación Marginal Dental , Diseño de Prótesis Dental , Diseño Asistido por Computadora , Coronas , Porcelana Dental , Humanos , Diente Molar
14.
Int J Comput Dent ; 24(2): 207-223, 2021 Jun 04.
Artículo en Inglés | MEDLINE | ID: mdl-34085505

RESUMEN

AIM: The aim of the present study was to compare inlay and onlay restorations fabricated from conventional impressions and two different digital impression systems in terms of clinical features and marginal fit. MATERIALS AND METHODS: Participants were randomly assigned to three groups according to the type of impression system used. The impressions were taken with polyvinyl siloxane silicone material for the control group (CON). For the digital impressions, Trios Pod Scanner (3Shape) was used for the TRIOS group and Cerec AC Omnicam (Sirona) for the CEREC group. A total of 40 IPS e.max CAD and 20 IPS e.max Press (both Ivoclar Vivadent) inlay and onlay restorations were then placed in 24 participants. Clinical evaluations, Plaque Index, Gingival Index, and pocket probing depth measurements were taken at baseline, 6 months, and 12 months using FDI criteria. The continuous margin percentages were quantitatively examined by scanning electron microscopy at baseline and 12 months. RESULTS: All the restorations showed clinically acceptable measurements at baseline, 6 months, and 12 months. The continuous margin evaluations showed no statistically significant difference between the groups. CONCLUSIONS: Based on the 12-month follow-up results, inlay and onlay restorations fabricated with digital impressions were found to be a reliable alternative to conventional impressions.


Asunto(s)
Diseño Asistido por Computadora , Incrustaciones , Técnica de Impresión Dental , Adaptación Marginal Dental , Diseño de Prótesis Dental , Humanos , Estudios Prospectivos
15.
Shanghai Kou Qiang Yi Xue ; 30(2): 191-195, 2021 Apr.
Artículo en Chino | MEDLINE | ID: mdl-34109361

RESUMEN

PURPOSE: To investigate the clinical performance of chairside monolithic lithium disilicate glass-ceramics computer-aided design(CAD)-computer aided manufacturing(CAM) crowns, and to analyze the influencing factors of cumulative survival rate. METHODS: Two hundred and fourteen patients who had chairside posterior lithium disilicate glass-ceramic CAD-CAM crowns in Peking University Shenzhen Hospital from March 2015 to March 2017 were enrolled. The crown preparations were milled using Cerec Omnicam system. The clinical and esthetic effects of the crowns were analyzed at 3, 6, 12, 24, and 36 months. The cumulative survival rate of crowns was calculated, and the effects of gender, age, pulp condition, tooth position and adhesive type on the cumulative survival rate were analyzed. SPSS 20.0 software package was used for statistical analysis. RESULTS: After a 36-month follow-up, the failed crowns were mainly caused by marginal integrity, crown fracture and loss of retention. During the observation period of 3, 6, 12, 24 and 36 months, the scores of color, shape, quality of proximal contact, and chewing ability were greater than 9. The cumulative survival rates were 100.00%, 96.17%, 94.89%, 92.77% and 91.06% at 3, 6, 12, 24 and 36 months, respectively. The cumulative survival rate had no significant difference among different gender, age, and dental pulp status(P>0.05). CONCLUSIONS: Chairside monolithic lithium disilicate glass-ceramic CAD-CAM crowns have a high 3-year cumulative survival rate and good esthetic outcome, which is not affected by gender, age, and pulp status with high clinical value.


Asunto(s)
Diseño de Prótesis Dental , Estética Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Porcelana Dental , Humanos , Ensayo de Materiales
16.
J Prosthet Dent ; 125(5): 804.e1-804.e6, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33934821

RESUMEN

STATEMENT OF PROBLEM: Agreement on the perfect virtual cement space value for computer-aided design and computer-aided manufacturing (CAD-CAM) implant-supported resin-ceramic crowns with the best marginal adaptation is lacking. The range of cement gap settings in some CAD design software programs is wide (0 to 200 µm), and manufacturer recommendations regarding the best cement gap setting for certain types of ceramics is not specific. PURPOSE: The purpose of this in vitro study was to evaluate the effect of virtual cement gap settings on the marginal fit of cemented resin-ceramic crowns on implant abutments. MATERIAL AND METHODS: Thirty implant analogs and matching stock abutments were coupled and implanted into autopolymerizing acrylic resin blocks. Three groups (n=10) of resin-ceramic molar crowns with 3 different virtual cement space settings (40, 60, and 100 µm) were designed by using a CAD design software program. The crowns were cemented over their corresponding abutments under a static load by using a specially designed cementing device. A scanning electron microscope was used to measure the mean vertical marginal gap (MG) for each group, where a total of 120 measurements for each of the 3 groups (12 sites per crown and 10 crowns per group) were evaluated. One-way analysis of variance and the post hoc Tukey pairwise comparison tests were used to analyze the data (α=.05). RESULTS: A significant difference (P<.001) was found between the MG values of the resin-ceramic implant-supported crowns fabricated by using the 3 cement space settings. The smallest MG was obtained with the 60-µm setting as compared with the 40-µm and 100-µm settings. CONCLUSIONS: A limited inverse relation was found between the MGs of CAD-CAM-fabricated resin-ceramic implant-supported crowns and the cement gap settings in the exocad software program. The smallest MGs were obtained when a 60-µm cement space value was used (P<.001).


Asunto(s)
Implantes Dentales , Adaptación Marginal Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Porcelana Dental , Diseño de Prótesis Dental
17.
Am J Dent ; 34(2): 91-96, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33940666

RESUMEN

PURPOSE: To evaluate and compare the flexural strength of three CAD-CAM glass-ceramic materials and to investigate the effect of various surface treatments on their flexural strength. METHODS: 120 rectangular specimens were fabricated from three different types of CAD-CAM ceramic blocks and were divided into three groups: zirconia-reinforced lithium silicate (Celtra Duo, Group 1), leucite-reinforced glass-ceramic (IPS Empress CAD, Group 2), and lithium disilicate ceramic (IPS e.max CAD, Group 3). Dimensions of the specimens were standardized to 14.5x12.5 mm and 1.5 mm thickness. Specimens in each group were randomized into four subgroups. The first subgroup (NS) did not undergo any surface treatment; the second subgroup (P) underwent polishing only; the third subgroup (G) underwent glazing only; and the fourth subgroup (PG) underwent both polishing and glazing surface treatments. Biaxial flexural strength (FS) testing was performed until fracture occurred; FS was calculated in MPa. All analyses were performed using SPSS version 24. RESULTS: Group NS2 showed the lowest FS (89.34 ± 25.30 MPa). Group PG3 showed a significantly higher FS (365.38 ± 52.52 MPa) than Group P3 (268.15 ± 48.34). There was a statistically significant difference among the material groups for each surface treatment: IPS e.max CAD showed the highest FS, which was significantly greater than that of both Celtra Duo and IPS Empress CAD. The combination of polishing and glazing surface treatment resulted in significantly higher flexural strength than polishing alone for all three materials tested. For each material, no significant difference was found between the following surface treatments: control and polishing-only surface treatments; glazing-alone and the combination of polishing and glazing surface treatments. For each surface treatment, Celtra Duo showed significantly lower flexural strength than IPS e.max CAD. However, it displayed higher flexural strength than IPS Empress CAD, although the difference was only significant for glazing and the combination of polishing and glazing. CLINICAL SIGNIFICANCE: This study provides the clinician with an estimate of the flexural strength of glass-ceramic materials and shows how various surface treatments affect their strength.


Asunto(s)
Cerámica , Resistencia Flexional , Diseño Asistido por Computadora , Ensayo de Materiales , Propiedades de Superficie
18.
Int J Esthet Dent ; 16(2): 144-167, 2021 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-33969972

RESUMEN

AIM: To investigate whether: 1) in the adhesive era, a full-crown restoration in a molar tooth is more resistant compared with an overlay-type restoration; b) a posterior indirect adhesive restoration (PIAR) is similar to a sound tooth from a mechanical point of view. MATERIALS AND METHODS: Seventy extracted molars were divided into five groups (1. Butt Joint; 2. Full Bevel; 3. Shoulder; 4. Full Crown; 5. Sound Tooth (control); N = 14) and prepared with four different PIAR overlay design types (according to an adhesthetics classification). Seven expert dentists performed all the preparation and cementation phases with codified protocols. A CAD/CAM workflow was used to realize the 56 monolithic lithium disilicate restorations. The samples were tested with thermomechanical aging (margin quality data will be given in Part 2 of this article series), and the resistance to fracture was then tested and analyzed. RESULTS AND CONCLUSIONS: In terms of fracture resistance in a situation of overload and within the limitations of the present study, it is possible to conclude that the Full Bevel group showed higher fracture strength than all the other groups. All PIAR restorations performed equally or better than the natural control tooth in the Sound Tooth group. The Full Crown group did not perform better than partial overlay PIAR. The fracture types were limited to the crown in 50% or more of the samples; the rest involved the cervical part of the root. The preparation design that involved the root the least was the Full Crown group (14%).


Asunto(s)
Cementos Dentales , Porcelana Dental , Cementación , Diseño Asistido por Computadora , Coronas , Diseño de Prótesis Dental , Fracaso de la Restauración Dental , Análisis del Estrés Dental , Humanos , Ensayo de Materiales , Diente Molar
19.
J Prosthodont ; 30(S2): 133-138, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33988280

RESUMEN

The use of computer aided design and computer aided manufacturing in the fabrication of complete removable dentures has demonstrated that the prostheses produced are superior in many ways to removable dentures produced using analog techniques. A variety of clinical workflows that take advantage of digital technology have been shown to shorten the number of appointments required to produce high quality prostheses. This paper presents an overview of additive manufacturing in contemporary removable complete denture workflows and describes effective three appointment clinical techniques using additive manufacturing to produce a clinical trial denture and definitive prosthesis.


Asunto(s)
Diseño Asistido por Computadora , Dentadura Completa , Dentadura Parcial , Flujo de Trabajo
20.
Compend Contin Educ Dent ; 42(4): 182-186, 2021 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-33960803

RESUMEN

This report presents a completely digital workflow utilizing digital intraoral scanning, rapid prototyping techniques, and a monolithic final restoration. A complete fixed prosthesis supported by six implants was used to replace a patient's periodontally compromised mandibular natural dentition. A staged approach was used in which a series of milled and 3D-printed provisional restorations were fabricated to help the patient transition to the dental implant rehabilitation. This cast-free approach allowed for increased patient comfort and greater time efficiency in clinical steps, as each provisional was digitally preplanned and readily available to the clinician before each step.


Asunto(s)
Implantes Dentales , Boca Edéntula , Diseño Asistido por Computadora , Diseño de Prótesis Dental , Prótesis Dental de Soporte Implantado , Humanos , Flujo de Trabajo
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