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1.
J Dent Sci ; 17(1): 63-69, 2022 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-35028021

RESUMEN

Background/purpose: Advancements in digital dentistry and the development of intraoral scanners (IOS) have provided clinicians with an accurate and efficient alternative to analog impressions. The aim of this study was to assess the accuracy of the marginal and internal fit of 5-unit monolithic zirconia fixed dental prostheses (FDPs) fabricated with CAD/CAM technology using direct and indirect digitalization methods. Material and methods: Three teeth in a maxillary typodont model were prepared to receive a 5-unit zirconia FDP. Six different groups were created according to the type of scanner (intraoral and extraoral) and the type of workflow. For direct workflow, the typodont was scanned with two different IOS (3Shape Trios 3 [3S-IOS] and Cerec Omnicam [C-IOS]). For indirect workflow, after conventional impressions were obtained, the impressions (IMP) were scanned with two different laboratory scanners (3S-IMP and C-IMP). After the impressions were poured, the stone (STN) casts were scanned with the same laboratory scanners (3S-STN and C-STN). Sixty 5-unit monolithic zirconia FDPs (10 in each group) were designed and milled. The marginal and internal fit was assessed. Results: The mean marginal gap values were 78.2±9 µm in the IOS group, 82.6± 9 µm in the IMP group, and 82.6±9 µm in the STN group, indicating no statistically significant differences among groups (p > 0.05). The mean axial gap values were 77.7 ± 10 µm in IOS group, 83.61 ± 15 µm in the IMP group, and 84.5±9 µm in the STN group, indicating no statistically significant differences among groups (p > 0.05). Conclusion: The marginal and internal fit of 5-unit monolithic zirconia FDPs fabricated with direct and indirect digital scans were similar. The smallest gap values were observed at the marginal region while the greatest gap values were detected at the occlusal region.

2.
Clin Oral Investig ; 2022 Jan 04.
Artículo en Inglés | MEDLINE | ID: mdl-34981252

RESUMEN

OBJECTIVES: To compare the accuracy (trueness and precision) of direct digitization of four different dental gap situation with two IOS (intraoral scanner). MATERIALS AND METHODS: Four partially edentulous polyurethane mandible models were used: (1) A (46, 45, 44 missing), (2) B (45, 44, 34, 35 missing), (3) C (42, 41, 31, 32 missing), and (4) D (full dentition). On each model, the same reference object was fixed between the second molars of both quadrants. A dataset (REF) of the reference object was generated by a coordinate measuring machine. Each model situation was scanned by (1) OMN (Cerec AC Omnicam) and (2) PRI (Cerec Primescan AC) (n = 30). Datasets of all 8 test groups (N = 240) were analyzed using inspection software to determine the linear aberrations in the X-, Y-, Z-axes and angular deviations. Mann-Whitney U and two-sample Kolmogorov-Smirnov tests were used to detect differences for trueness and precision. RESULTS: PRI revealed higher trueness and precision in most of the measured parameters ([Formula: see text] 120.95 to 175.01 µm, [Formula: see text](x) - 58.50 to - 9.40 µm, [Formula: see text] (z) - 70.35 to 63.50 µm), while OMN showed higher trueness for [Formula: see text] (y) regardless of model situation (- 104.90 to 34.55 µm). Model D revealed the highest trueness and precision in most of the measured parameters regardless of IOS ([Formula: see text] 120.95 to 195.74 µm, [Formula: see text] (x) - 9.40 to 66.75 µm,[Formula: see text] (y) - 14.55 to 51.50 µm, [Formula: see text] (z) 63.50 to 120.75 µm). CONCLUSIONS: PRI demonstrated higher accuracy in the X- and Z-axes, while OMN depicted higher trueness in the Y-axis. For PRI, Model A revealed the highest distortion, while for OMN, Model B produced the largest aberrations in most parameters. Clinical relevance Current results suggest that both investigated IOS are sufficiently accurate for the manufacturing of tooth-borne restorations and orthodontic appliances. However, both hardware specifications of IOS and the presence of edentulous gaps in the dental model have an influence on the accuracy of the virtual model dataset.

3.
BMC Oral Health ; 21(1): 625, 2021 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-34876103

RESUMEN

BACKGROUND/PURPOSE: How long do lithium disilicate restorations last before they fail? The aim of this study was to assess the success rate of four different types of restorations made from lithium disilicate. MATERIALS AND METHODS: A total of 87,203 ceramic restorations, classified into four different types (inlay or onlay, veneers (Vs), single crowns (SCs), and fixed partial dentures (FPDs)), were used. All were made of lithium disilicate (IPS e.Max CAD) with Cerec Inlab CAD/CAM system (Sirona Dental Systems, Bensheim, Germany). They were reported by dentists and entered in the database of the private B&R Dental Center between March 2015 and June 2020 and assessed retrospectively up to a period of 5 years based on the following parameters: failure rate and cause of failures (ceramic fracture, debonding, marginal adaptation, color match, endodontic intervention, periodontal disease, and secondary caries). Failure distribution according to gender, arch, and teeth type was also evaluated. The time-dependent time-to-failure/complication and their differences were calculated in months according to the Kaplan Meier and log-rank tests. The Chi-squared test (p 0.05) was used to assess the variations in causes of failure rates between different restorations. RESULTS: Kaplan Meier test showed overall cumulative survival probability of lithium disilicate restorations for up to years was 85.08%. Inlay/onlay and Vs ceramic restorations showed highest cumulative survival probability (99.4%, 98.6, respectively). FPDs had the least cumulative survival probability (52.9%) which was significantly (P < 0.00001) higher than for other ceramic restorations using the log-rank test. Moreover, overall time-dependent time-to-failure/complication occurred after 52.373 months according to Kaplan-Meier (CI: lower bound: 51.875 months; upper bound: 52.871 months). Ceramic fracture in both FPDs and SCs (27.6% and 26.6%, respectively) and debonding in Vs (12.7%) were significant as the main reasons for failure (P = 0.000). The failure rate was significantly higher for the maxillary arch than the mandibular arch (P = 0.021). Fracture and marginal discrepancy were more frequent in the molar region (77.5% and 14.75%, respectively) and significantly higher here than in the anterior and premolar regions (P = 0.000). CONCLUSION: The medium-term performance of lithium disilicate is ideal. Ceramic fracture was the most common cause of failure in SCs and FPDs. FPDs presented with the highest failure rate based on evaluation for up to 5 years.

4.
Int J Comput Dent ; 24(4): 429-438, 2021 Dec 21.
Artículo en Inglés | MEDLINE | ID: mdl-34931778

RESUMEN

The significantly faster fabrication technique of chairside restorations with the aid of the Cerec Primemill milling unit makes it possible to restore an entire quadrant in a reasonable amount of time. Furthermore, the procedure described in this article made it possible to use a new type of medium-strength ceramic that achieved a very good esthetic result overall.


Asunto(s)
Porcelana Dental , Diseño de Prótesis Dental , Cerámica , Diseño Asistido por Computadora , Coronas , Estética Dental , Humanos
5.
Dent Mater ; 2021 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-34961642

RESUMEN

OBJECTIVES: Lithium-based glass-ceramics are currently dominating the landscape of dental restorative ceramic materials, with new products taking the market by storm in the last years. Though, the difference among all these new and old products is not readily accessible for the practitioner, who faces the dilemma of reaching a blind choice or trusting manufacturers' marketing brochures. To add confusion, new compositions tend to wear material terminologies inherited from vanguard dental lithium disilicates, disregarding accuracy. Here we aim to characterize such materials for their microstructure, crystalline fraction, glass chemistry and mechanical properties. METHODS: Eleven commercial dental lithium-based glass ceramics were evaluated: IPS e.max® CAD, IPS e.max® Press, Celtra® Duo, Suprinity® PC, Initial™ LiSi Press, Initial™ LiSi Block, Amber® Mill, Amber® Press, N!CE®, Obsidian® and CEREC Tessera™. The chemical composition of their base glasses was measured by X-Ray Fluorescence Spectroscopy (XRF) and Inductive Coupled Plasma Optical Emission Spectroscopy (ICP-OES), as well as the composition of their residual glass by subtracting the oxides bound in the crystallized fraction, characterized by X-Ray Diffraction (XRD) and Rietveld refinement, and quantified accurately using the G-factor method (QXRD). The crystallization behavior is revealed by differential scanning calorimetry (DSC) curves. Elastic constants are provided from Resonant Ultrasound Spectroscopy (RUS) and the fracture toughness measured by the Ball-on-Three-Balls method (B3B- K Ic). The microstructure is revealed by field-emission scanning electron microscopy (FE-SEM). RESULTS: The base glasses showed a wide range of SiO2 /Li2O ratios, from 1.5 to 3.0, with the degree of depolymerization dropping from ½ to 2/3 of the initial connectivity. Materials contained Li2SiO3+Li3PO4, Li2SiO3+Li3PO4+Li2Si2O5, Li2Si2O5+Li3PO4+ Cristobalite and/or Quartz and Li2Si2O5+Li3 PO4+LiAlSi2O6, in crystallinity degrees from 45 to 80 vol%. Crystalline phases could be traced to their crystallization peaks on the DSC curves. Pressable materials and IPS e.max® CAD were the only material showing micrometric phases, with N!CE® and Initial™ LiSi Block showing solely nanometric crystals, with the rest presenting a mixture of submicrometric and nanometric particles. Fracture toughness from 1.45 to 2.30 MPa√m were measured, with the linear correlation to crystalline fraction breaking down for submicrometric and nanometric crystal phases. SIGNIFICANCE: Dental lithium-based silicate glass-ceramics cannot be all put in the same bag, as differences exist in chemical composition, microstructure, crystallinity and mechanical properties. Pressable materials still perform better mechanically than CAM/CAM blocks, which loose resistance to fracture when crystal phases enter the submicrometric and nanometric range.

6.
Int J Prosthodont ; 2021 Dec 17.
Artículo en Inglés | MEDLINE | ID: mdl-34919097

RESUMEN

PURPOSE: This in vitro study was conducted to evaluate the marginal accuracy of all-ceramic onlay restorations and prototypes fabricated using additive and subtractive methods. MATERIALS AND METHODS: Ten typodont first molars were prepared and scanned two times using two different scanners: ARCTICA AutoScan (KaVo Dental) and CEREC Omnicam (Dentsply Sirona). The two groups of virtual models were used to design two groups of virtual onlay restorations using two different CAD software (n = 10 each group) and exported in STL files. Each group of STL files was converted to physical onlay restorations and prototypes by using three different methods; these included two additive manufacturing techniques, stereolithography apparatus (SLA) and digital light processing (DLP), and one subtractive technique, e.max milling using the KaVo Everest system and the Dentsply Sirona inLab MC X5. A digital microscope was used to evaluate the marginal fit around the onlay restorations or prototypes on the typodont teeth. RESULTS: All evaluated groups showed mean marginal gaps between 59 and 84 µm. No statistically significant differences were found when comparing the marginal accuracy of onlay restorations fabricated by the subtractive method and onlay prototypes from the two additive methods, SLA (P = .70) and DLP (P = .21). CONCLUSION: All the models evaluated produced marginal gaps within the reported acceptable clinical range. Thus, these subtractive and additive methods may be considered suitable for onlay restoration production.

7.
Eur J Dent ; 2021 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-34847612

RESUMEN

OBJECTIVE: The aim of this study was to evaluate the influence of different marginal designs (deep chamfer, vertical, and modified vertical with reverse shoulder) on the fracture strength and failure modes of monolithic zirconia crowns. MATERIALS AND METHODS: Thirty sound human maxillary first premolar teeth with comparable size were used in this study. The teeth were divided randomly into three groups according to the preparation design (n = 10): (1) group A: teeth prepared with a deep chamfer finish line; (2) group B: teeth prepared with vertical preparation; and (3) group C: teeth prepared with modified vertical preparation, where a reverse shoulder of 1 mm was placed on the buccal surface at the junction of middle and occlusal thirds. All samples were scanned by using an intraoral scanner (CEREC Omnicam, Sirona, Germany), and then the crowns were designed by using Sirona InLab 20.0 software and milled with a 5-axis machine. Each crown was then cemented on its respective tooth with self-adhesive resin cement by using a custom-made cementation device. A single load to failure test was used to assess the fracture load of each crown by using a computerized universal testing machine that automatically recorded the fracture load of each sample in Newton (N). STATISTICAL ANALYSIS: The data were analyzed statistically by using one-way analysis of variance test and Bonferroni test at a level of significance of 0.05. RESULTS: The highest mean of fracture load was recorded by chamfer (2,969.8 N), which followed by modified vertical (2,899.3 N) and the lowest mean of fracture load was recorded by vertical (2,717.9 N). One-way ANOVA test revealed a significant difference among the three groups. Bonferroni test showed a significant difference between group A and group B, while a nonsignificant difference was revealed between group C with group A and group B. CONCLUSION: Within the limitations of this in vitro study, the mean values of fracture strength of monolithic zirconia crowns of all groups were higher than the maximum occlusal forces in the premolar region. The modification of the vertical preparation with a reverse shoulder placed at the buccal surface improved the fracture strength up to the point that it was statistically nonsignificant with the chamfer group.

8.
J Prosthodont ; 2021 Nov 27.
Artículo en Inglés | MEDLINE | ID: mdl-34837276

RESUMEN

PURPOSE: The aim was to evaluate the effect of different preparation depths for inlay-retained fixed partial dentures on the accuracy of intraoral scanners. MATERIALS AND METHODS: Tooth preparations for two inlay-retained fixed partial dentures were done and divided according to depth of the preparation. Group A: 2mm pulpal floor depth, 3mm gingival floor depth and Group B: 3mm pulpal floor depth, 4mm gingival floor depth. The CEREC Omnicam4.4.4, Omnicam4.6.2. Trios3 and Medit i500 intraoral scanners were used in this study. Tooth preparations were scanned by each scanner 10 times. The STL files obtained from the intraoral scanners were compared to the reference models (trueness) and within each test group (precision) using a 3D comparison software. Data were then statistically analyzed. RESULTS: Regarding trueness, two-way ANOVA revealed significant differences between the different types of scanners (p<0.001) (Omnicam4.4.4: 65.09 ±2.87 Omnicam4.6.1: 52.73 ±3.31 Medit i500: 58.45 ±2.63 Trios 3: 41.79 ±4.42). Preparation depth had no significant influence on the trueness (p = 0.083). For precision two-way ANOVA revealed significant differences between the different types of scanners (p<0.001). Preparation depth had no significant influence on the precision (p = 0.111). Statistically significant interactions were found between the different variables. CONCLUSIONS: The depth of preparation did not have an influence on the accuracy of different scanners. However, the type of scanner influenced the accuracy of digital impressions with Trios3 showing the highest accuracy. This article is protected by copyright. All rights reserved.

9.
Zhonghua Kou Qiang Yi Xue Za Zhi ; 56(11): 1092-1097, 2021 Nov 09.
Artículo en Chino | MEDLINE | ID: mdl-34763404

RESUMEN

Objective: To comparatively evaluate the accuracy and the scan time of three full-arch scan strategies on the head-simulator, to explore a full-arch scan strategy with better clinical operability and high accuracy. Methods: A cross-controlled study design was used. A model with melamine-formaldehyde resin teeth and silica gel gingiva of an upper dental arch which can be fixed on a head simulator was scanned with an optical scanner (ATOS Core) in order to obtain the standard tessellation language (STL) dataset as reference. Intraoral scans were performed on the model fixed on the head simulator with four intraoral scanners (IOS) [A (TRIOS 3), B (CS 3600), C (CEREC Omnicam), D (iTero)]. The STL datasets were obtained from each of the four different IOS systems by using three scan strategies (scan strategies 1, 2 and 3 were composed of 10, 5 and 7 paths respectively) all by one attending doctor with 3 years of intraoral scanning experience. For each scanner and each scan strategy, nine scans were acquired. And the scan time was recorded for each scan. Following the scan strategy, the scan path was completed to obtain a full-arch digital model, and the scan time was recorded as full-arch scan time. Complementary scans were performed to fill the missing image, and this scan time was recorded as complementary scan time. The total scan time was obtained by adding full-arch scan time and complementary scan time. Through the Geomagic Wrap software, the three-dimensional (3D) models were overlaid by best fit alignment function and compared to obtain the root mean square values of the discrepancies by 3D compare function. The intraoral scanning datasets were compared with the reference for trueness. The nine intraoral scanning datasets were cross compared with same scan strategy and same intraoral scanner for precision. Results: There were no significant differences among the three scan strategies for trueness (P>0.05), while the differences among the three scan strategies for precision were affected by difference IOSs (P<0.05), and only scan strategy 3 showed the highest precision with all the four IOS. The full-arch scan time of scan strategies 1, 2 and 3 were (130±24), (72±17) and (90±19) s respectively (P<0.05). For complementary scan time, scan strategy 2 [(50±24) s] took longer time than scan strategy 1 [(26±18) s] and scan strategy [(25±21) s] (P<0.05), while no significant differences between the latter two (P>0.05). For total scan time, scan strategy 1 [(156±31) s] took longer time than scan strategy 2 [(122±30) s ] and scan strategy 3 [(115±29) s ] (P<0.05), while no significant differences between the latter two (P>0.05). Conclusions: Full-arch scanning on the head-simulator with scan strategy 3 which can obtain scanning datasets with high accuracy, was more convenient to operate and took shorter scan time, and is generally suitable for intraoral scanners commonly used in clinic.


Asunto(s)
Técnica de Impresión Dental , Diseño Asistido por Computadora , Arco Dental , Imagenología Tridimensional
10.
J Conserv Dent ; 24(2): 190-194, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34759588

RESUMEN

Purpose: To evaluate the marginal and internal fit of endocrowns with different computer-aided design/computer-aided manufacturing (CAD-CAM) materials by measuring them with a stereomicroscope (µm). Materials and Methods: A mandibular first molar typodont tooth was prepared to receive an endocrown. The preparation was scanned using an extra-oral scanner. Endocrowns (n = 20) were fabricated using lithium disilicate (IPS e. max CAD LT block; CEREC Ivoclar Vivadent, Liechtenstein) and polyetheretherketone (PEEK) (breCAM. BioHPP®; Bredent, UK) using CAD-CAM technique. Marginal gap was evaluated using a stereomicroscope at the midpoint of all four surfaces (mid buccal, mid lingual, mid mesial, mid distal). This was followed by sectioning of the endocrowns in a sagittal plane along with the prepared tooth to evaluate the internal fit at four different points (A, B, C, D) using a stereomicroscope. Statistical analysis was performed using one-way analysis of variance test. Results: Mean values of marginal gap of lithium disilicate and PEEK endocrowns are 56.6 ± 6.1 µm and 81.3 ± 10.1 µm, respectively. Mean value internal gaps of lithium disilicate and PEEK endocrowns are 158.2 ± 11.1 µm and 199.1 ± 13 µm, respectively. Results in the present study have shown that the marginal and internal fits of lithium disilicate endocrowns are superior to that of PEEK endocrowns. Conclusions: Based on the outcomes of this in vitro study, the marginal and internal fit of lithium disilicate endocrowns is better than PEEK endocrowns. The marginal gap clinically acceptable is <120 µm. The marginal gap values recorded in this study are within the acceptable range for both materials.

11.
J Adv Prosthodont ; 13(5): 316-326, 2021 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-34780580

RESUMEN

PURPOSE: Purpose of this in vitro study was to determine the accuracy of different intraoral scans versus laboratory scans of impressions and casts for the digitization of an edentulous maxilla. MATERIALS AND METHODS: A PEEK model of an edentulous maxilla, featuring four hemispheres on the alveolar ridges in region 13, 17, 23 and 27, was industrially digitized to obtain a reference dataset (REF). Intraoral scans using Cerec Primescan AC (PRI) and Cerec AC Omnicam (OMN), as well as conventional impressions (scannable polyvinyl siloxane) were carried out (n = 25). Conventional impressions (E5I) and referring plaster casts were scanned with the inEOS X5 (E5M). All datasets were exported in STL and analyzed (Geomagic Qualify). Linear and angular differences were evaluated by virtually constructed measurement points in the centers of the hemispheres (P13, P17, P23, P27) and lines between the points (P17-P13, P17-P23, P17-P27). Kolmogorov-Smirnov test and Shapiro-Wilk test were performed to test for normal distribution, Kruskal-Wallis-H test, and Mann-Whitney-U test to detect significant differences in trueness, followed by 2-sample Kolmogorov-Smirnov test to detect significant differences in precision (P < .008). RESULTS: Group PRI showed the highest trueness in linear and angular parameters (P < .001), while group E5I showed the highest precision (P < .001). CONCLUSION: Intraoral scan data obtained using Primescan showed the highest trueness while the indirect digitization of impressions showed the highest precision. To enhance the workflow, indirect digitization of the impression itself appears to be a reasonable technique, as it combines fast access to the digital workflow with the possibility of functional impression of mucosal areas.

12.
J Indian Prosthodont Soc ; 21(4): 425-429, 2021.
Artículo en Inglés | MEDLINE | ID: mdl-34810372

RESUMEN

Aims: To evaluate the flexural properties of computer-aided design-computer-aided manufacturing (CAD-CAM) milled posts fabricated from the experimental fibre-reinforced composite disks in different fibre direction, and to compare the flexural properties of the CAD-CAM milled posts to those of commercial prefabricated posts, RelyX and FRC PostecPlus. Settings and Design: In vitro comparative study. Materials and Methods: E-glass fibre was used to fabricate the CAD-CAM composite disks. The fibres were prepared in unidirectional and multidirectional arrangements into the epoxy resin, at 70% by weight. The disk was milled by the Cerec InLab CAD-CAM system to fabricate a post. Ten posts for each type of disk were prepared. Two types of commercial fibre posts, RelyX fibre post, and FRC PostecPlus were used as control. The three-point bending test was performed. Statistical Analysis Used: The data were analysed using one-way ANOVA and Game-Howell post-hoc test. Results: The results indicated that both commercial fibre posts had the highest flexural strength and flexural modulus. The unidirectional experimental post yielded significantly lower values in both flexural strengths (739.1 ± 24.1 MPa) and flexural modulus (21.0 ± 3.5 GPa) compared to the control posts, while the multidirectional experimental posts had extremely low flexural strength and flexural modulus. Conclusions: The direction of the fibres significantly influenced the mechanical properties of the posts. The experimental unidirectional fibre-reinforced composite disk showed the potential to be used as a CAD-CAM disk for post and core fabrication.


Asunto(s)
Resinas Compuestas , Vidrio , Diseño Asistido por Computadora , Ensayo de Materiales
13.
J Esthet Restor Dent ; 2021 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-34608739

RESUMEN

OBJECTIVE: This study aimed to evaluate the influence of the presence of adjacent teeth on the accuracy of intraoral scanning (IOS) systems for class II inlay preparation. MATERIALS AND METHODS: The mesio-occlusal inlay preparation was prepared in an anatomical model of the maxillary molar. The prepared tooth was secured to a typodont with the mesial adjacent tooth removed or in situ. Ten digital impressions of the inlay preparation were acquired using three IOS systems (CEREC Primescan, 3Shape TRIOS 3, and Medit i500). A laboratory scanner (3Shape E3) was used to obtain the reference scan data. The mean absolute deviation values were calculated to evaluate the accuracy of the digital models. RESULTS: The group with the adjacent teeth present showed lower trueness and precision compared to that without the adjacent tooth (p < .05). Significant differences were observed among the IOS systems (p < .05). Primescan showed the highest accuracy, irrespective of the presence of adjacent teeth. CONCLUSIONS: The presence of the adjacent tooth negatively affected the accuracy of all the IOSs tested. Although the performance of Primescan was superior to that of TRIOS 3 and i500, each IOS system showed clinically acceptable levels of accuracy for class II inlay preparation. CLINICAL SIGNIFICANCE: The adjacent tooth can be a confounding factor for accurate digital impressions of class II inlay preparation.

14.
J Dent ; 115: 103837, 2021 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-34624421

RESUMEN

Objectives To determine the clinical performance of partial ceramic crowns (PCCs) luted with a conventional resin cement combined with a universal adhesive without or with selective enamel etching or luted with a self-adhesive resin cement. Methods In a split-mouth design, each three CAD/CAM-PCCs (Vita Mark II, Cerec) were placed in 50 patients. Two PCCs were luted with a conventional resin cement (RelyX Ultimate) combined with a universal adhesive (Scotchbond Universal) without (SB-E) or with (SB+E) selective enamel etching. The third PCC was luted with a self-adhesive resin cement (RelyX Unicem 2; RXU). Chi-square tests (α≤0.05) were applied. Based on clinical failures (complete debonding or need for replacement of the restorations), Kaplan-Meier survival analysis was performed. Results 31 patients were evaluated clinically using FDI criteria at 39 months. Clinically acceptable results were detected over time, except for "fracture of material and retention" (inacceptable fractures and debondings). Within materials, statistically significant differences (p ≤ 0.003) between baseline and 39 months were found for "marginal adaptation" and "marginal staining". At 39-month, SB+E and SB-E showed significantly better results compared to RXU in "marginal adaptation"(p ≤ 0.021) and "marginal staining"(p ≤ 0.013). Kaplan-Meier analysis showed higher survival rates after 39 months for SB+E (96%) and SB-E (88%) compared to RXU (69%) with statistically significant differences between RXU vs. SB-E (p = 0.022) and RXU vs. SB+E (p ≤ 0.001). Conclusions After 39-months, PCCs luted with the self-adhesive resin cement exhibited a statistically significant inferior survival rate compared to restorations luted with the conventional resin cement combined with a universal adhesive without or with selective enamel etching. Clinical significance Currently, self-adhesive resin cements cannot be recommended for luting partial ceramic crowns. However, the standard adhesive luting procedure comprising a universal adhesive and luting composite yielded good clinical results for more than 3 years irrespectively of application of a selective enamel etching step.

15.
Clin Oral Investig ; 2021 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-34596770

RESUMEN

OBJECTIVES: The aim of this study is to compare the sensitivity of T-Scan digital occlusal analysis system and the occlusal analysis mode of the CEREC Omnicam system, which is mainly used for design/production, using the data recorded at the maximum intercuspal position. MATERIALS AND METHODS: Occlusal recordings were obtained from healthy 20 females and 20 males aged 18-25 at the maximum intercuspal position. Records were saved as.jpeg format and transferred to Adobe Photoshop CS6 program. Blue, green, and red colors (shown by the same color codes in both systems) representing light, intense, and tight contacts, respectively, were evaluated in terms of the pixel counts. For statistical comparison, the differences between the systems independent sample T test and, between the genders, one sample T test were used (α = 0.05). RESULTS: The total numbers of pixels of all colors which are evaluated with T-Scan and CEREC Omnicam in females were 31,296.6 and 15,745, respectively, and in males 39,812.3 and 17,462, respectively. In both systems, the blue contact area is the most seen. For all colors tested, T-Scan recorded more contact than those of CEREC Omnicam in both genders and statistically significant difference was found between two systems for all colors. In both systems, recorded contacts are significantly higher in men than in women. Compared with women, 27% more contact area was recorded in men with T-Scan and 11% more with CEREC Omnicam was obtained. CONCLUSIONS: While T-Scan was found sensitive even in the diagnosis of light contacts, the CEREC Omnicam was found sensitive only in the diagnosis of tight contacts. CLINICAL RELEVANCE: Although both T-Scan and CEREC Omnicam are effective in occlusal analysis, T-Scan's sensitivity was found to be higher. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT04798729.

16.
Eur J Dent Educ ; 2021 Sep 19.
Artículo en Inglés | MEDLINE | ID: mdl-34541757

RESUMEN

INTRODUCTION: The computer-aided design/computer-aided manufacturing (CAD/CAM) technology has revolutionised dentistry at present. An operator's skills can affect the overall clinical duration and marginal accuracy of the prosthesis fabricated through this workflow. The aim of this study was to assess the effect of CAD/CAM hands-on training compared with that of a self-instructional video on the performance of dental students in digital impression and fabrication of a CAD/CAM crown. METHODS: In this cross-sectional study, 30 undergraduate dental students were shown a CEREC demonstration video. Each operator then captured a digital impression using the intra-oral scanner, and a crown was subsequently milled. All participants underwent a training course before repeating the process. Marginal discrepancy for each crown on its abutment tooth was measured before and after training using a stereomicroscope and was evaluated using Wilcoxon signed rank test. The duration taken for the process was recorded before and after training and evaluated using paired t-test. RESULTS: The overall mean ±standard deviation marginal adaptation for the CEREC crowns was 78.15 ± 42.83 µm before training and 52.41 ± 17.12 µm after training. The Wilcoxon signed rank test found significant difference (p < .05) in terms of marginal adaptation of crowns fabricated before and after training. Paired t-tests showed that the time efficiency after training significantly improved compared with that before training. CONCLUSIONS: Training with guided feedback is crucial to improve the time efficiency of making a digital impression and marginal adaptation of fixed prosthesis using the CAD/CAM technology.

17.
Chin J Dent Res ; 24(3): 185-189, 2021 Sep 07.
Artículo en Inglés | MEDLINE | ID: mdl-34491013

RESUMEN

OBJECTIVE: To evaluate the clinical performance of direct composite restorations using the modified stamp technique (MST) in vivo. METHODS: A total of 30 posterior teeth with undermining caries were randomly divided into two groups and then restored using the MST and conventional technique (CT), respectively. 3D images of the occlusal surface were obtained using an intraoral scanner (CEREC Omnicam, Dentsply Sirona, Charlotte, NC, USA) before and after treatment and the differences between these two 3D images were analysed with reverse engineering software. Statistical analysis was performed using a one-way analysis of variance (ANOVA) combined with a least significant difference (LSD) post hoc test using SPSS 20.0 software (IBM, Armonk, NY, USA). RESULTS: The statistical analysis revealed that the average root mean square (RMS) values of best fit alignment errors were significantly different between groups (P < 0.01). The average RMS values in the MST and CT groups were 0.0738 ± 0.0279 and 0.1638 ± 0.0682, respectively. The LSD post hoc test revealed that the value was significant smaller in the MST group than in the CT group. CONCLUSION: The MST was effective in direct composite restoration. The morphological consistency of the occlusal surface using the MST was better than with the CT.


Asunto(s)
Diseño Asistido por Computadora , Diente , Resinas Compuestas , Restauración Dental Permanente , Imagenología Tridimensional
18.
Int J Comput Dent ; 24(3): 283-291, 2021 Sep 23.
Artículo en Inglés | MEDLINE | ID: mdl-34553893

RESUMEN

AIM: Recording maximum intercuspal position (ICP) is critical for many dental procedures. Digital ICP from intraoral scanners (IOSs) produces variable results. This study investigated the sources of error in recording ICP using an IOS and a recently reported method. MATERIALS AND METHODS: A set of dentate models was scanned three times in a Rexcan DS2 scanner. The models were then scanned six times with a Cerec Omnicam IOS. For each scan, 10 bilateral 'bite' scans were performed (n = 6 x 10 bite registrations). Three key points were identified on the first intraoral scan and automatically transplanted onto all subsequent scans. The key point method was validated by using a 'secondary' key point transplantation from each scan back to the three laboratory scans, where the location of each point was compared using one-way analysis of variance. Full-arch errors on the intraoral scans were identified by comparing the intermolar key point distances on all intraoral scans against the 'gold standard' model scans. Precision of the virtual occlusion was identified by comparing the distance between all upper-lower key point pairs for all intraoral scans using intraclass correlation. RESULTS: Automatic key points were transplanted to model scans with standard deviations (SDs) in location of ≤ 0.003 mm (upper [maxillary]) and ≤ 0.004 mm (lower [mandibular]) arch. The intermolar width of the intraoral scans had a mean error of 0.183 (± 0.061) mm (upper) and 0.017 (± 0.092) mm (lower) arch. Interocclusal key point separation showed poor reliability across groups, but good precision (SD < 0.022 mm) within groups. CONCLUSION: Automatic key points allowed valid linear distance comparisons across repeated scans. Poor trueness and precision in the full-arch intraoral scans adversely affected interocclusal registrations. Bite scan precision had a less detrimental effect on interocclusal registration.


Asunto(s)
Técnica de Impresión Dental , Diseño Asistido por Computadora , Arco Dental/diagnóstico por imagen , Humanos , Imagenología Tridimensional , Reproducibilidad de los Resultados
19.
Am J Dent ; 34(4): 179-185, 2021 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-34370908

RESUMEN

PURPOSE: To compare the effect of the immediate dentin sealing (IDS) and resin cement type on fracture resistance of Class II mesio-occluso-distal (MOD) zirconia inlay restorations. METHODS: 90 Class II MOD cavities on freshly extracted human mandibular third molars, prepared with a high-speed handpiece, were divided into two groups: those with IDS (CR+) and without IDS (CR-). The CEREC system was used to prepare zirconia inlays from Katana super translucent multi-layered blocks. The inlays were cemented with one of three resin cements: RelyX Unicem 2 (RU), Multilink Automix (MA), or Super-Bond (SB). These specimens were stored in water at 37°C for 24 hours and exposed to 5,000 thermal cycles. A vertical load was applied with a metal sphere (Φ 6-mm) on a material testing system, with a crosshead speed of 0.5 mm/minute, until the specimen fractured. Fracture resistance was measured for each tooth, and the fractures were categorized according to Burke's classification. Statistical analyses were conducted using two-way ANOVA and Tukey's honest significant difference tests (P< 0.05). RESULTS: No significant differences in tooth fracture resistance were identified between the CR+ and CR- groups. The SB group had a significantly higher fracture resistance compared to that of the MA group. Fracture morphology showed many mode IV fractures in all groups. IDS did not affect tooth fracture resistance, although there was a significant difference in tooth fracture resistance for different resin cement types used with Class II MOD zirconia inlay restorations. CLINICAL SIGNIFICANCE: Zirconia inlay restorations provide excellent mechanical performance, morphology, and esthetic appearance. In vitro, zirconia inlays cemented with any luting resin cement restored tooth fracture resistance to levels similar to that of intact teeth. Fracture resistance varied among the different resin cements.


Asunto(s)
Cementos de Resina , Fracturas de los Dientes , Resinas Compuestas , Porcelana Dental , Análisis del Estrés Dental , Dentina , Humanos , Incrustaciones , Ensayo de Materiales , Circonio
20.
Quintessence Int ; 52(10): 904-910, 2021 Oct 19.
Artículo en Inglés | MEDLINE | ID: mdl-34410071

RESUMEN

OBJECTIVE: To evaluate, in vivo, trueness and precision of two intraoral scanners, CEREC Omnicam (OMNI) and CEREC Primescan (PRIM), compared to a conventional impression serving as a master model. METHOD AND MATERIALS: Impressions were performed for seven participants. For each participant, conventional polyvinylsiloxane impression and digital impressions using two intraoral scanners, OMNI (software 4.6; CEREC ORTHO Protocol) and PRIM (10 digital impressions per participant, per scanner), were made. Conventional impression was digitized with a laboratory scanner (INEOS X5), and used as reference model. .STL files were superimposed with software (Geomagic Control X) using the tools Initial Alignment and Best Fit Alignment, and trueness and precision were evaluated. Statistical evaluation was performed with Shapiro-Wilk and Mann-Whitney tests (P < .05). RESULTS: Total mean trueness for the OMNI system was 56.45 ± 7.80 µm, and 47.29 ± 5.47 µm for the PRIM system. Regarding precision, values from the OMNI system were 42.47 ± 6.91 µm and from the PRIM system 21.86 ± 4.40 µm. PRIM presented better results for both trueness (P = .000) and precision (P = .000) when compared to OMNI. CONCLUSIONS: PRIM provided a better combination of trueness and precision than its predecessor OMNI. However, both PRIM and OMNI performed acceptably when performing indirect restorations, according to the current acceptable thresholds, considering both trueness and precision. CLINICAL IMPLICATIONS: Full-arch impressions with Primescan presented more precision and trueness than Omnicam; however, compared to previous reported values of conventional impressions, they still presented lower accuracy.


Asunto(s)
Técnica de Impresión Dental , Diseño Asistido por Computadora , Arco Dental , Humanos , Imagenología Tridimensional
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