Publications by authors named "Tim Joda"

70 Publications

The challenge of eHealth data in orthodontics.

Am J Orthod Dentofacial Orthop 2021 Mar;159(3):393-395

School of Dental Medicine, Department of Orthodontics, University of Bern, Bern, Switzerland. Electronic address:

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http://dx.doi.org/10.1016/j.ajodo.2020.12.002DOI Listing
March 2021

Impact of high-speed sintering on accuracy and fit of 4 mol% yttria-stabilized tetragonal zirconia polycrystals (4Y-TZPs).

Int J Prosthodont 2021 Feb 12. Epub 2021 Feb 12.

Purpose: To investigate the impact of high-speed sintering on the accuracy (trueness and reproducibility) and fit of 4Y-TZP full-coverage single-unit fixed dental prostheses (FDPs) and three-unit FDPs.

Materials And Methods: Single-unit FDPs, conventional three-unit FDPs, and cantilever three-unit FDPs (N = 108; n = 12 per subgroup) were fabricated from: (1) high-speed sintered (1,580°C, about 20 minutes) multi-layer 4Y-TZP (Zolid RS, Amann Girrbach; ZMLH group), as well as two conventionally sintered (1,450°C, about 10 hours) materials: (2) multi-layer 4Y-TZP (Zolid Gen-X, Amann Girrbach; ZMLC group) and (3) monochrome 4Y-TZP (Ceramill Zolid HT+ PS, Amann Girrbach; ZMOC group). All specimens were scanned. Trueness, reproducibility, and fit were measured with 3D analysis software. For data analysis, Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U tests were performed (α = .05).

Results: Three-unit FDPs made from ZMLH presented a deterioration of accuracy in comparison to ZMLC (P ≤ .001 to .008). The influence of highspeed sintering on marginal and general fit was not clinically relevant (P = .154 to .877).

Conclusion: High-speed sintering influenced the accuracy of 4Y-TZP full-coverage single-unit and three-unit FDPs. However, no clinically relevant impact on fit was observed.
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http://dx.doi.org/10.11607/ijp.7428DOI Listing
February 2021

Mechanical stability of dental CAD-CAM restoration materials made of monolithic zirconia, lithium disilicate, and lithium disilicate-strengthened aluminosilicate glass ceramic with and without fatigue conditions.

J Prosthet Dent 2021 Feb 2. Epub 2021 Feb 2.

Professor, Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, Basel, Switzerland.

Statement Of Problem: Studies investigating the mechanical stability of lithium disilicate-strengthened aluminosilicate glass ceramic that do not require sintering after milling compared with other computer-aided design and computer-aided manufacturing (CAD-CAM) materials are lacking.

Purpose: The purpose of this in vitro study was to investigate the flexural strength of CAD-CAM zirconia, lithium disilicate, and lithium disilicate-strengthened aluminosilicate glass ceramics with and without fatigue conditions.

Material And Methods: Specimens (N=90, n=15) (12×4×3 mm) from the following CAD-CAM materials were prepared and polished: lithium disilicate glass ceramic (IPS e.max CAD); lithium disilicate-strengthened aluminosilicate glass ceramic (N!ce); and zirconium dioxide ceramic (IPS e.max ZirCAD). All specimens were divided into 2 subgroups: immediate testing without aging and simulation of aging by using a mastication simulator for 1 200 000 cycles (5 °C-55 °C). Thereafter, flexural strength testing was performed by using a universal testing machine (1 mm/min) on nonaged and aged specimens. The data were evaluated by using nonparametric 2-way ANOVA and Wilcoxon rank post hoc tests (α=.05).

Results: Both the material type and aging significantly affected the results (P<.001). The interaction was not significant (P>.05). Under nonaged conditions, zirconium dioxide ceramic (1136 ±162 MPa) showed significantly higher mean ±standard deviation flexural strength (P<.001) than lithium disilicate (304 ±34 MPa) and lithium disilicate-strengthened aluminosilicate glass ceramic (202 ±17 MPa). The glass ceramic groups were also significantly different from each other (P<.001). After aging, zirconium dioxide (1087.9 ±185.3 MPa) also presented significantly higher mean ±standard deviation flexural strength (P<.001) than lithium disilicate (259 ±62 MPa) and lithium disilicate-strengthened aluminosilicate glass ceramic (172 ±11 MPa) (P<.001). Aging significantly decreased the flexural strength of lithium disilicate (14.6%) (P=.03) and lithium disilicate-strengthened aluminosilicate glass ceramic (14.5%) (P=.01) but had minimal effect on the zirconium dioxide ceramic (4.3%) (P=.29).

Conclusions: Among the tested CAD-CAM materials, the mechanical performance of lithium disilicate-strengthened aluminosilicate glass ceramic was comparable with that of lithium disilicate and considerably lower than that of zirconia. Aging decreased the flexural strength of both lithium disilicate and lithium disilicate-strengthened aluminosilicate glass ceramic.
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http://dx.doi.org/10.1016/j.prosdent.2020.12.002DOI Listing
February 2021

Digital fixed complete-arch rehabilitation: From virtual articulator mounting to clinical delivery.

J Prosthet Dent 2020 Dec 11. Epub 2020 Dec 11.

Clinical lecturer and research fellow, Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, Mich. Electronic address:

The virtual articulator is a tool that reproduces the relationship between the jaws in a virtual environment. The purpose of this clinical report was to describe a completely digital protocol starting from the virtual articulator mounting to developing static and dynamic occlusion in a complex prosthetic rehabilitation.
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http://dx.doi.org/10.1016/j.prosdent.2020.08.049DOI Listing
December 2020

Influence of Preparation Design, Marginal Gingiva Location, and Tooth Morphology on the Accuracy of Digital Impressions for Full-Crown Restorations: An In Vitro Investigation.

J Clin Med 2020 Dec 9;9(12). Epub 2020 Dec 9.

Department of Reconstructive Dentistry, UZB University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

(1) Background: Intraoral optical scanning (IOS) has gained increased importance in prosthodontics. The aim of this in vitro study was to analyze the IOS accuracy for treatment with full crowns, considering possible influencing factors. (2) Methods: Two tooth morphologies, each with four different finish-line designs for tooth preparation and epi- or supragingival locations, were digitally designed, 3D-printed, and post-processed for 16 sample abutment teeth. Specimens were digitized using a laboratory scanner to generate reference STLs (Standard Tessellation Language), and were secondary-scanned with two IOS systems five times each in a complete-arch model scenario (Trios 3 Pod, Primescan AC). For accuracy, a best-fit algorithm (Final Surface) was used to analyze deviations of the abutment teeth based on 160 IOS-STLs compared to the reference STLs (16 preparations × 2 IOS-systems × 5 scans per tooth). (3) Results: Analysis revealed homogenous findings with high accuracy for intra- and inter-group comparisons for both IOS systems, with mean values of 80% quantiles from 20 ± 2 μm to 50 ± 5 μm. Supragingival finishing lines demonstrated significantly higher accuracy than epigingival margins when comparing each preparation ( 0.05), whereas tangential preparations exhibited similar results independent of the gingival location. Morphology of anterior versus posterior teeth showed slightly better results in favor of molars in combination with shoulder preparations only. (4) Conclusion: The clinical challenge for the treatment with full crowns following digital impressions is the location of the prospective restoration margin related to the distance to the gingiva. However, the overall accuracy for all abutment teeth was very high; thus, the factors tested are unlikely to have a strong clinical impact.
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http://dx.doi.org/10.3390/jcm9123984DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7763051PMC
December 2020

Comparison of different intraoral scanning techniques on the completely edentulous maxilla: An in vitro 3-dimensional comparative analysis.

J Prosthet Dent 2020 Dec 24;124(6):762.e1-762.e8. Epub 2020 Oct 24.

Research Professor, Division of Prosthodontics and Digital Dentistry, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University "Federico II" of Naples, Naples, Italy.

Statement Of Problem: Information about the accuracy of intraoral scanners for the edentulous maxilla is lacking.

Purpose: The purpose of this in vitro study was to compare the accuracy of 3 different intraoral scanner techniques on a completely edentulous maxilla typodont.

Material And Methods: Two completely edentulous maxillary typodonts with (wrinkled typodont) and without (smooth typodont) palatal rugae were used as reference and were scanned by using an industrial metrological machine to obtain 2 digital reference scans in standard tessellation language (STL) format (dWT and dST). Three different scanning techniques were investigated: in the buccopalatal technique, the buccal vestibule was scanned with a longitudinal movement ending on the palatal vault with a posteroanterior direction; the S-shaped technique was based on an alternate palatobuccal and buccopalatal scan along the ridge; in the palatobuccal technique, the palate was scanned with a circular movement and then with a longitudinal one along the buccal vestibule. Consecutively, 6 types of scans were obtained (n=10), namely wrinkled typodont/buccopalatal technique, wrinkled typodont/S-shaped technique, wrinkled typodont/palatobuccal technique (wrinkled typodont), smooth typodont/buccopalatal technique, smooth typodont/S-shaped technique, and smooth typodont/palatobuccal technique (smooth typodont). Scans in STL format were imported into a dedicated software program, and trueness and precision were evaluated in μm. In addition to descriptive statistics (95% confidence interval), a 2-factor ANOVA on the data ranks, the Kruskal-Wallis, and the Dunn tests were performed to analyze differences among groups (α=.05).

Results: Mean values for trueness (95% confidence interval) were wrinkled typodont/buccopalatal technique=48.7 (37.8-59.5); wrinkled typodont/S-shaped technique=65.9 (54.9-77.4); wrinkled typodont/palatobuccal technique=109.7 (96.1-123.4); smooth typodont/buccopalatal technique=48.1 (42.4-53.7); smooth typodont/S-shaped technique=56.4 (43.9-68.9); smooth typodont/palatobuccal technique=61.1 (53.3-69), with statistically significant differences for wrinkled typodont/buccopalatal technique versus wrinkled typodont/palatobuccal technique (P<.001), buccopalatal technique versus palatobuccal technique (P<.001), and wrinkled typodont versus smooth typodont (P=.002). Mean values for precision (95% confidence interval) were wrinkled typodont/buccopalatal technique=46.7 (29.7-63.7); wrinkled typodont/S-shaped technique=53.6 (37.6-69.7); wrinkled typodont/palatobuccal technique=90 (59.1-120.9); smooth typodont/buccopalatal technique=46 (39.7-52.3); smooth typodont/S-shaped technique=76 (55.5-96.6); smooth typodont/palatobuccal technique=52.9 (41.9-63.8); with statistically significant differences for buccopalatal technique versus palatobuccal technique (P=.032) and wrinkled typodont/buccopalatal technique versus wrinkled typodont/palatobuccal technique (P=.012).

Conclusions: Smooth typodont scans showed better trueness than wrinkled typodont scans. Buccopalatal technique showed better mean values for trueness and precision than palatobuccal technique only in the wrinkled typodont scenario, while the other scanning approaches did not show significant differences in either tested configuration.
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http://dx.doi.org/10.1016/j.prosdent.2020.07.017DOI Listing
December 2020

Accuracy of a chairside intraoral scanner compared with a laboratory scanner for the completely edentulous maxilla: An in vitro 3-dimensional comparative analysis.

J Prosthet Dent 2020 Dec 24;124(6):761.e1-761.e7. Epub 2020 Oct 24.

Research Professor, Division of Prosthodontics and Digital Dentistry, Department of Neurosciences, Reproductive and Odontostomatological Sciences, University "Federico II" of Naples, Naples, Italy.

Statement Of Problem: Intraoral scanners are promising options for removable prosthodontics. However, analog aids, including occlusion rims, are still used, as a completely digital workflow is challenging and scientific evidence on the topic is scarce.

Purpose: The purpose of this in vitro study was to assess and compare the trueness and precision of scans obtained from a reference typodont of a completely edentulous maxilla by using an intraoral scanner (TRIOS 3 Pod; 3Shape A/S) with scans obtained by using a laboratory scanner (DScan 3; EGS S.R.L.) from both Type IV stone casts and polysulfide impressions.

Material And Methods: The polyurethane resin reference typodont was replicated from a clinical cast and was scanned with a metrological machine to obtain a reference scan. Ten digital casts were obtained by applying standardized scanning strategies to the reference typodont with the intraoral scanner. A device was created to make 10 consistent polysulfide impressions, and a scan of each impression was made with the laboratory scanner and then digitally reversed to obtain 10 digital reversed casts. Ten Type IV stone casts were poured and then scanned with the laboratory scanner to obtain 10 digital extraoral scanner casts. The scans in standard tessellation language (STL) format were imported into a dedicated software program, and the trueness and precision were calculated in μm. In addition to descriptive statistics (confidence interval 95%), 1-way ANOVA followed by the Bonferroni test or the Kruskal-Wallis and the Dunn tests were used to analyze differences among groups (α=.05).

Results: The trueness values (95% confidence interval) were digital intraoral scanner cast=48.7 (37.8-59.5), digital reversed cast=249.9 (121.3-378.5), and digital extraoral scanner cast=308.8 (186.6-430.9); significant differences were detected between digital intraoral scanner cast and digital reversed cast (P<.001) and between digital IOS casts and digital extraoral scanner cast (P<.001). The precision values (95% confidence interval) were digital intraoral scanner cast=46.7 (29.7-63.7), digital reversed cast=271.2 (94.6-447.8), and digital extraoral scanner cast=341.4 (175.5-507.3); significant differences were detected between digital intraoral scanner cast and digital reversed cast (P=.003) and between digital intraoral scanner cast and digital extraoral scanner cast (P=.001).

Conclusions: Directly scanning a solid typodont of a completely edentulous maxilla with the intraoral scanner produced better trueness and precision than scanning the polysulfide impressions or the stone casts with a laboratory scanner.
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http://dx.doi.org/10.1016/j.prosdent.2020.07.018DOI Listing
December 2020

Retrospective analysis of the long-term effect of subgingival air polishing in supportive periodontal therapy.

J Clin Periodontol 2021 Feb 9;48(2):263-271. Epub 2020 Nov 9.

Clinic for Periodontology and Conservative Dentistry, University of Muenster, Münster, Germany.

Aim: Glycine powder air polishing (GPAP) procedure has become popular. Aim of the analysis was to compare the clinical outcomes during supportive periodontal therapy (SPT) of subgingival application of GPAP with those using sole conventional mechanical debridement (SC).

Material And Methods: Over a median SPT period of 5.3 years (re-evaluation through last observation), the GPAP cohort (n = 263) received supra- and subgingival biofilm removal with GPAP. Supragingival calculus was removed using curets and sonic scalers here. Patients in the SC cohort (n = 264) were treated with sonic scalers, curets and rubber cup polishing only. Changes in, that is pocket probing depth (PPD) and furcation involvement were assessed retrospectively. A bootstrapping equivalence testing method in line with the principle of the two one-sided tests (TOST) procedure was used to compare clinical outcomes.

Results: The GPAP procedure was statistically equivalent to SC regarding the number of sites with stable PPDs (83.3%; IQR 68.8%, 91.0% vs. 84.0%; IQR 77.8%, 90.0%). However, in the GPAP cohort, a trend towards deterioration in furcation status (no equivalence) was noted.

Conclusions: In periodontal maintenance, the use of GPAP instead of mechanical plaque removal does not improve the clinical outcome. It seems to be contraindicated to treat furcation defects with GPAP only.
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http://dx.doi.org/10.1111/jcpe.13392DOI Listing
February 2021

Clinical outcome of metal- and all-ceramic resin-bonded fixed dental prostheses.

J Prosthodont Res 2020 Oct 6. Epub 2020 Oct 6.

Department of Reconstructive Dentistry University Center for Dental Medicine Basel, University of Basel.

Purpose: The aim of this retrospective cohort study was to investigate the long-term outcome of metal- and all-ceramic resin-bonded fixed dental prosthesis (RBFDP) up to 17 years, and to evaluate potential factors influencing the risk for complications.

Methods: Patients who were treated with RBFDP to replace teeth in the anterior or first premolar region in an university setting were identified from electronic records. Data collection comprised dental and periodontal parameters, periapical radiographs, and assessment of the RBFDP. Patient-reported satisfaction was evaluated on visual analog scales (VAS), and 5-year cumulative survival and success rates were calculated. Cox regression models were used to compare metal- versus all-ceramic RBFDPs.

Results: Seventy-one patients with RBFDP replacing 65 anterior teeth and 6 premolars were included with a mean observation period of 56.1 (±42.7) months. RBFDP cumulative survival rate was 86.7% and cumulative success rate 71.7% after 5 years, with no significant difference between metal-and all-ceramic RBFDPs. The risk for RBFDP failure was significantly higher with more than one pontic (OR 6.1; p=0.033), or negative pulp vitality testing of abutments (OR 7.3; p=0.042), while complications tended to be increased with two-wings compared to one-wing RBFDP (OR 5.4; p=0.054).

Conclusions: Metal- and all-ceramic RBFDPs facilitated good long-term results, particularly with one-wing, one-cantilever, and vital abutment teeth.
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http://dx.doi.org/10.2186/jpr.JPR_D_20_00014DOI Listing
October 2020

Indirect Digital Workflow for Virtual Cross-Mounting of Fixed Implant-Supported Prostheses to Create a 3D Virtual Patient.

J Prosthodont 2021 Feb 9;30(2):177-182. Epub 2020 Sep 9.

Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI.

Mounting dental casts in an articulator is an important prerequisite for prosthodontic rehabilitation cases where the design of an accurate static and dynamic occlusion is needed. Virtual mounting can be achieved through the superimposition of various 3D images acquired from the hard and soft tissues of the patient. The purpose of this technical report is to describe a digital cross-mounting technique for patients undergoing implant-supported fixed prosthetic treatment. Through the use of face scanning, intraoral scanning, and cone beam computed tomography, this technique enables creation of a 3D virtual patient with occlusal registration in centric relation. Ultimately, the described methodology allows for the fabrication of definitive full-mouth implant-supported fixed prostheses.
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http://dx.doi.org/10.1111/jopr.13247DOI Listing
February 2021

Virtual Articulators and Virtual Mounting Procedures: Where Do We Stand?

J Prosthodont 2021 Jan 2;30(1):24-35. Epub 2020 Sep 2.

Department of Periodontics and Oral Medicine, University of Michigan School of Dentistry, Ann Arbor, MI.

A virtual articulator is a computer software tool that is capable of reproducing the relationship between the jaws and simulating jaw movement. It has gradually gained research interest in dentistry over the past decade. In prosthodontics, the virtual articulator should be considered as an additional diagnostic and treatment planning tool to the mechanical articulator, especially in complex cases involving alterations to the vertical dimension of occlusion. Numerous authors have reported on the available digital methodologies used for the assembly of virtual arch models in a virtual articulator, focusing their attention on topics such as the virtual facebow and digital occlusal registration. To correctly simulate jaw movement, the jaw models have to be digitalized and properly mounted on the virtual articulator. The aim of this review was to discuss the current knowledge surrounding the various techniques and methodologies related to virtual mounting in dentistry, and whether virtual articulators will become commonplace in clinical practice in the future. This review also traces the history of the virtual articulator up to its current state and discusses recently developed approaches and workflows for virtual mounting based on current knowledge and technological devices.
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http://dx.doi.org/10.1111/jopr.13240DOI Listing
January 2021

Mandibular implant-supported fixed complete dental prostheses on implants with ultrashort and standard length: A pilot treatment.

J Prosthet Dent 2020 Jul 28. Epub 2020 Jul 28.

Full Professor, Department of Reconstructive Dentistry and Gerodontology, School of Dental Medicine, University of Bern, Bern, Switzerland.

Edentulous patients may be restored with complete-arch implant-supported fixed complete dental prostheses (IFCDPs) on angled distal implants or on parallel implants distributed equally across the mandible to increase the area of support. A treatment is presented to introduce the clinical concept of providing edentulous patients with an implant-supported fixed complete dental prosthesison parallel tissue-level implants in the mandible with standard length implants interforaminally and ultrashort implants distally. A structured prosthetic approach was used for the tooth arrangement with a modified workflow as per the Biofunctional Prosthetic System adapted for static computer-aided implant surgery (s-CAIS) and computer-aided design and computer-aided manufacturing (CAD-CAM) of the screw-retained implant-supported fixed complete dental prosthesis. The concept offered advantages in challenging anatomic, surgical, and prosthetic conditions; providing distal nonangled abutments and implant platforms, which were straightforward to clean. If necessary, the prosthesis could have been easily converted into a removable overdenture using the existing digital prosthetic arrangement. Should implant removal be required, the extrashort implants can be removed with minimal surgical risk or morbidity.
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http://dx.doi.org/10.1016/j.prosdent.2020.04.013DOI Listing
July 2020

Clinical Performance of Partial and Full-Coverage Fixed Dental Restorations Fabricated from Hybrid Polymer and Ceramic CAD/CAM Materials: A Systematic Review and Meta-Analysis.

J Clin Med 2020 Jul 4;9(7). Epub 2020 Jul 4.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

The aim of this systematic review and meta-analysis was to evaluate the clinical performance of tooth-borne partial and full-coverage fixed dental prosthesis fabricated using hybrid polymer and ceramic CAD/CAM materials regarding their biologic, technical and esthetical outcomes. PICOS search strategy was applied using MEDLINE and were searched for RCTs and case control studies by two reviewers using MeSH Terms. Bias risk was evaluated using the Cochrane collaboration tool and Newcastle-Ottawa assessment scale. A meta-analysis was conducted to calculate the mean long-term survival difference of both materials at two different periods (≤24, ≥36 months(m)). Mean differences in biologic, technical and esthetical complications of partial vs. full crown reconstructions were analyzed using software package R ( 0.05). 28 studies included in the systematic review and 25 studies in the meta-analysis. The overall survival rate was 99% (0.95-1.00, ≤24 m) and dropped to 95% (0.87-0.98, ≥36 m), while the overall success ratio was 88% (0.54-0.98; ≤24 m) vs. 77% (0.62-0.88; ≥36 m). No significance, neither for the follow-up time points, nor for biologic, technical and esthetical (88% vs. 77%; 90% vs. 74%; 96% vs. 95%) outcomes was overserved. A significance was found for the technical/clinical performance between full 93% (0.88-0.96) and partial 64% (0.34-0.86) crowns. The biologic success rate of partial crowns with 69% (0.42-0.87) was lower, but not significant compared to 91% (0.79-0.97) of full crowns. The esthetical success rate of partial crowns with 90% (0.65-0.98) was lower, but not significant compared to 99% (0.92-1.00) of full crowns.
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http://dx.doi.org/10.3390/jcm9072107DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7408958PMC
July 2020

Registering Maxillomandibular Relation to Create a Virtual Patient Integrated with a Virtual Articulator for Complex Implant Rehabilitation: A Clinical Report.

J Prosthodont 2020 Aug 17;29(7):553-557. Epub 2020 Aug 17.

State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Disease, West China Hospital of Stomatology, Sichuan University, Chengdu, PR China.

The virtual patient, a unique computer simulation of the patient's face, teeth, oral mucosa, and bone, provides an extraordinary mechanism for digital dental implant surgery planning and prosthetic design. However, the seamless registration of digital scans with functional information in the context of a virtual articulator remains a challenge. This report describes the treatment of a 47-year-old male with full-mouth guided immediate implant placement and immediate loading of CAD/CAM interim prostheses. Utilizing a novel digital workflow, a multifactorial registration of the vertical dimension of occlusion, centric occlusion, and facebow record were completed digitally and paired within a digital articulator. Utilizing this innovative approach, a complex treatment plan and procedure was executed smoothly with a successful prosthetic outcome demonstrating good fit, occlusion, esthetics, and patient reported satisfaction.
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http://dx.doi.org/10.1111/jopr.13204DOI Listing
August 2020

Impact of Aging on the Accuracy of 3D-Printed Dental Models: An In Vitro Investigation.

J Clin Med 2020 May 12;9(5). Epub 2020 May 12.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

The aim of this in vitro study was to analyze the impact of model aging on the accuracy of 3D-printed dental models. A maxillary full-arch reference model with prepared teeth for a three-unit fixed dental prosthesis was scanned ten times with an intraoral scanner (3Shape TRIOS Pod) and ten models were 3D printed (Straumann P-Series). All models were stored under constant conditions and digitized with a desktop scanner after 1 day; 1 week; and 2, 3, and 4 weeks. For accuracy, a best-fit algorithm was used to analyze the deviations of the abutment teeth (GFaI e.V Final Surface). were used for comparisons with the level of significance set at α = 0.05. Deviation analysis of the tested models showed homogenous intragroup distance calculations at each timepoint. The most accurate result was for 1 day of aging (3.3 ± 1.3 µm). A continuous decrease in accuracy was observed with each aging stage from day 1 to week 4. A time-dependent difference was statistically significant after 3 weeks ( = 0.0008) and 4 weeks ( < 0.0001). Based on these findings, dental models should not be used longer than 3 to 4 weeks after 3D printing for the fabrication of definitive prosthetic reconstructions.
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http://dx.doi.org/10.3390/jcm9051436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7291208PMC
May 2020

Digital Undergraduate Education in Dentistry: A Systematic Review.

Int J Environ Res Public Health 2020 05 7;17(9). Epub 2020 May 7.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

The aim of this systematic review was to investigate current penetration and educational quality enhancements from digitalization in the dental curriculum. Using a modified PICO strategy, the literature was searched using PubMed supplemented with a manual search to identify English-language articles published between 1994 and 2020 that reported the use of digital techniques in dental education. A total of 211 articles were identified by electronic search, of which 55 articles were selected for inclusion and supplemented with 27 additional publications retrieved by manual search, resulting in 82 studies that were included in the review. Publications were categorized into five areas of digital dental education: Web-based knowledge transfer and e-learning, digital surface mapping, dental simulator motor skills (including intraoral optical scanning), digital radiography, and surveys related to the penetration and acceptance of digital education. This review demonstrates that digitalization offers great potential to revolutionize dental education to help prepare future dentists for their daily practice. More interactive and intuitive e-learning possibilities will arise to stimulate an enjoyable and meaningful educational experience with 24/7 facilities. Augmented and virtual reality technology will likely play a dominant role in the future of dental education.
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http://dx.doi.org/10.3390/ijerph17093269DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7246576PMC
May 2020

Creating a virtual patient for completely edentulous computer-aided implant surgery: A dental technique.

J Prosthet Dent 2020 May 4. Epub 2020 May 4.

Associate Professor, Department of Biologic & Materials Sciences, Division of Prosthodontics, University of Michigan School of Dentistry, Ann Arbor, Mich. Electronic address:

A fully digital workflow for generating a virtual patient for completely edentulous computer-aided implant surgery is described. Existing dentures are temporarily relined with a radiopaque dental silicone material, and a cone beam computed tomography scan is made with the relined denture inserted. Then, scans of the relined denture are made with an intraoral scanner. The radiopaque silicone material increases the stability of the dentures and allows the a cone beam computed tomography images and the scans of the dentures to be superimposed to create a virtual patient. This technique may reduce laboratory work steps, clinical chairside time, and treatment costs.
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http://dx.doi.org/10.1016/j.prosdent.2020.02.026DOI Listing
May 2020

In-vitro polishing of CAD/CAM ceramic restorations: An evaluation with SEM and confocal profilometry.

J Mech Behav Biomed Mater 2020 07 3;107:103761. Epub 2020 Apr 3.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, Switzerland.

Aim: The objective of this In-vitro investigation was to analyze and compare the surface after polishing of 63 all-ceramic restorations fabricated out of monolithic zirconium dioxide (ZIR), lithium disilicate (LS) or feldspathic ceramic (FC) under standardized laboratory conditions with different protocols. The primary outcome was defined as the roughness (R/S) of different ceramic surfaces after distinctive polishing procedures.

Material And Methods: The study set-up consisted of three main groups: ZIR, LS, FC (20 crowns each), every group divided into two sub-groups (10 crowns each) depending on the polishing method. The untouched glazed surface of one crown per material served as a control. Every crown displayed a defined supra-contact at the palatal cusp which was removed with a fine grain (38-45 μm) diamond bur. Surface polishing was carried out with either a two-step system (one kit for zirconium dioxide (ZIR), another kit for lithium disilicate (LS) and feldspatic ceramic (FC)), or a three-step system (ZIR, LS, FC) under standardized conditions. Roughness parameters (R and S) were measured by means of confocal profilometry. Specimens were also visually inspected with scanning electron microscopy (SEM). Statistical analyses were performed using SPSS Statistics software.

Results: Visual examination of the specimens using SEM showed several inhomogeneities on the glazed surface of the control samples, i.e. pores and particles. On every test sample, the grinding curves of the diamond bur were still recognizable. Polishing revealed similar median R 0.491 μm (ZIR) and 0.434 μm (LS) after two-step polishing (p = 0.754), and 0.311 μm (ZIR) and 0.208 μm (LS) after three-step polishing (p = 0.917). Surface roughness in group FC measured 0.889 μm (FC) after the two-step polishing process and 0.903 μm (FC) following three-step surface refinement. No significant difference was detectable between surface roughness of glazed controls compared to either polished surfaces with two-step or three-step treatment within one material. ZIR and LS presented significantly lower median roughness R after two-step and three-step procedures than test samples of FC, measured subsequent to either of the polishing methods (p = 0.016, p = 0.009).

Conclusion: The surface roughness of ZIR, LS and FC crowns after the use of chairside polishing kits was comparable with the roughness measured before occlusal adjustment. A two-step procedure showed as good results as a three-step process. A smoother surface was obtained for ZIR and LS compared to FC with both polishing protocols.
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http://dx.doi.org/10.1016/j.jmbbm.2020.103761DOI Listing
July 2020

Big Data and Digitalization in Dentistry: A Systematic Review of the Ethical Issues.

Int J Environ Res Public Health 2020 04 6;17(7). Epub 2020 Apr 6.

Institute for Biomedical Ethics, University of Basel, 4056 Basel, Switzerland.

Big Data and Internet and Communication Technologies (ICT) are being increasingly implemented in the healthcare sector. Similarly, research in the field of dental medicine is exploring the potential beneficial uses of digital data both for dental practice and in research. As digitalization is raising numerous novel and unpredictable ethical challenges in the biomedical context, our purpose in this study is to map the debate on the currently discussed ethical issues in digital dentistry through a systematic review of the literature. Four databases (Web of Science, Pub Med, Scopus, and Cinahl) were systematically searched. The study results highlight how most of the issues discussed by the retrieved literature are in line with the ethical challenges that digital technologies are introducing in healthcare such as privacy, anonymity, security, and informed consent. In addition, image forgery aimed at scientific misconduct and insurance fraud was frequently reported, together with issues of online professionalism and commercial interests sought through digital means.
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http://dx.doi.org/10.3390/ijerph17072495DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177351PMC
April 2020

Digital Oral Medicine for the Elderly.

Int J Environ Res Public Health 2020 03 25;17(7). Epub 2020 Mar 25.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

Sustainable oral care of the elderly requires a holistic view of aging, which must extend far beyond the narrow field of dental expertise to help reduce the effects of sociobiological changes on oral health in good time. Digital technologies now extend into all aspects of daily life. This review summarizes the diverse digital opportunities that may help address the complex challenges in Gerodontology. Systemic patient management is at the center of these descriptions, while the application of digital tools for purely dental treatment protocols is deliberately avoided.
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http://dx.doi.org/10.3390/ijerph17072171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7177661PMC
March 2020

Recent Trends and Future Direction of Dental Research in the Digital Era.

Int J Environ Res Public Health 2020 03 18;17(6). Epub 2020 Mar 18.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, 4058 Basel, Switzerland.

The digital transformation in dental medicine, based on electronic health data information, is recognized as one of the major game-changers of the 21st century to tackle present and upcoming challenges in dental and oral healthcare. This opinion letter focuses on the estimated top five trends and innovations of this new digital era, with potential to decisively influence the direction of dental research: (1) rapid prototyping (RP), (2) augmented and virtual reality (AR/VR), (3) artificial intelligence (AI) and machine learning (ML), (4) personalized (dental) medicine, and (5) tele-healthcare. Digital dentistry requires managing expectations pragmatically and ensuring transparency for all stakeholders: patients, healthcare providers, university and research institutions, the medtech industry, insurance, public media, and state policy. It should not be claimed or implied that digital smart data technologies will replace humans providing dental expertise and the capacity for patient empathy. The dental team that controls digital applications remains the key and will continue to play the central role in treating patients. In this context, the latest trend word is created: augmented intelligence, e.g., the meaningful combination of digital applications paired with human qualities and abilities in order to achieve improved dental and oral healthcare, ensuring quality of life.
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http://dx.doi.org/10.3390/ijerph17061987DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7143449PMC
March 2020

Removable Dental Prosthesis 2.0: Digital from A to Z?

Swiss Dent J 2020 Mar;130(3):229-235

Klinik für Rekonstruktive Zahnmedizin, Universitäres Zentrum für Zahnmedizin Basel, Universität Basel

This case report presents the treatment of a partially edentulous patient with a clasp-retained removable dental prosthesis (RDP) using both, digital and conventional workflows. Differences were demonstrated in impression taking, bite registration, manufacturing of models, prosthetic set-up, framework design and production; the technical steps for the finish of the RDPs were identical and (currently) still dependent on manual skills. The digitally 3D-printed framework were favored by the patient and the dentist due to the precise fit. The number of manual steps will be continuously reduced applying digital technologies for the treatment with RDPs, resulting in shortened clinical and technical work time and higher precision of the final prosthetic restoration. In addition, the use of intraoral scanners is more patient-friendly than classic impressions with elastomers. Technological advancements are required to eliminate today’s limitations and enable a complete digital workflow, even without any physical models. Removable Dental Prosthesis 2.0: yes – but not yet completely from A to Z.
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March 2020

Long-Term Observation of Post Copings Retaining Overdenture Prostheses.

Int J Prosthodont 2020 Mar/Apr;33(2):169-175

Purpose: To investigate the long-term (up to 20 years) outcomes of customized post copings (PC) and to evaluate potential factors influencing the risk for complications.

Materials And Methods: Patients treated with PC-retained overdenture prostheses (OD) in a university setting were selected. Data collected included dental and periodontal parameters, periapical radiographs, and assessment of the OD design. Patient-reported satisfaction levels were evaluated using visual analog scales (VAS), and 20-year cumulative survival and success rates were calculated.

Results: A total of 73 patients with 81 ODs and 152 PCs were included. PC survival rate was 80.9%, and the success rate amounted to 64.5% after a mean observation period of 105.4 (± 67.9; range: 6 to 240) months. The 20-year cumulative PC rates were 91.5% for survival and 79.3% for success. Activation of matrices was more frequent with ball attachments than with cylindrical retention (odds ratio [OR] 0.43; 95% confidence interval [CI] 0.2 to 0.94; P = .034). Cylindrical retention was rated significantly better at 96% (interquartile range [IQR] 89.5% to 100%) compared to ball attachment at 88% (IQR 79% to 98.2%; P = .012). The risk for PC complications was higher for OD designs with coverage of the periodontal tissues compared to open designs (OR 0.34; 95% CI 0.15 to 0.78; P = .010).

Conclusion: Customized PCs on natural abutment teeth for the retention of ODs are a valid treatment in partially dentate patients. Correct prosthesis design and integration into a regular dental hygiene program are mandatory factors for long-term success.
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http://dx.doi.org/10.11607/ijp.6629DOI Listing
February 2020

Oral disorders in patients with newly diagnosed haematological diseases.

Clin Oral Investig 2020 Sep 2;24(9):3085-3091. Epub 2020 Jan 2.

Department of Oral Health & Medicine, University Center for Dental Medicine Basel, University of Basel, Hebelstrasse 3, CH-4055, Basel, Switzerland.

Objective: This study aimed to examine saliva flow rates and prevalence of dental and periodontal diseases of patients with newly diagnosed severe haematological diseases and compare these findings with age-matched controls of normal population.

Methods: A total of 149 patients diagnosed with haematological diseases aimed to be treated with haematological stem cell transplantation between 2008 and 2018 and 154 controls were included in the study. A dental examination was performed for patients within a maximum of 6 months after diagnosis. Differences were compared in terms of the stimulated salivary flow rate (SSFR); decayed, missing and filled teeth (DMFT) index; number of teeth; caries prevalence; presence of periodontitis and acute infections.

Results: The mean SSFR of the patient group was significantly lower (1.1 ml/min ± 0.7 ml/min) than the mean SSFR of the controls (1.3 ml/min ± 0.5 ml/min; p = 0.004). The number of caries lesions was significantly higher in the patient group (mean ± SD, 1.1 ± 1.9) than in the control group (mean ± SD, 0.4 ± 1.2; p < 0.001). There were fewer teeth and a higher DMFT index in the patient group compared to the control group, but the differences were not significant. Acute symptomatic infections were observed in eight (5.4%) patients and in none of the controls (p < 0.01).

Conclusions And Clinical Relevance: Oral examinations in patients with newly diagnosed severe haematological disease demonstrated a higher prevalence of caries, acute infections and lower mean SSFR compared with the controls. These findings support the recommendations for early dental examination at the time of diagnosis.
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http://dx.doi.org/10.1007/s00784-019-03178-3DOI Listing
September 2020

A pilot trial on lithium disilicate partial crowns using a novel prosthodontic functional index for teeth (FIT).

BMC Oral Health 2019 12 9;19(1):276. Epub 2019 Dec 9.

Department of Reconstructive Dentistry, University Center for of Dental Medicine, Basel, Switzerland.

Background: Lithium disilicate is now a well accepted material for indirect restorations. The aim of this trial was to evaluate two lithium disilicate systems using a novel prosthodontic Functional Index for Teeth (FIT).

Methods: Partial adhesive crowns on natural abutment posterior teeth were made on sixty patients. Patients were divided into two groups: Group 1 IPS e.max press (Ivoclar-Vivadent, Schaan, Liecthestein), and Group 2 Initial LiSi press (GC Co., Tokyo, Japan). The restorations were followed-up for 3 years, and the FIT evaluation was performed at last recall. The FIT is composed of seven variables (Interproximal, Occlusion, Design, Mucosa, Bone, Biology and Margins), each of them are evaluated using a 0-1-2 scoring scheme, and is investigated by an oral radiograph and occlusal and buccal pictures. More in details, three variables have the three scores made on the presence or not of major, minor or no discrepancy (for 'Interproximal', 'Occlusion' and 'Design'), presence or not of keratinized and attached gingiva ('Mucosa'), presence of bone loss > 1.5 mm, < 1.5 mm or not detectable ('Bone'), presence or not of Bleeding on Probing and or Plaque Index ('Biology'), presence of detectable gap and marginal stain or not ('Margins'). The Mann-Whitney 'U' test was used and the level of significance was set at p < 0.05. Also, "success" of the crowns (restoration in place without any biological or technical complication) and "survival" (restoration still in place with biological or technical complication) were evaluated.

Results: Regarding FIT scores, all partial crowns showed a stable level of the alveolar crest without detectable signs of bone loss in the radiographic analysis. All other evaluated parameters showed a high score, between 1.73 and 2. No statistically significant difference emerged between the two groups in any of the assessed variables (p > 0.05). All FIT scores were compatible with the outcome of clinical success and no one restoration was replaced or repaired and the success rate was 100%.

Conclusions: The results showed that it is possible to evaluate the clinical performance of partial crowns using FIT. The FIT proved to be an effective tool to monitor the performance of the restorations and their compatibility with periodontal tissues at the recall. The FIT can be really helpful for a standardized evaluation of the quality of the therapy in prosthodontic dentistry. The two lithium disilicate materials showed similar results after 3 years of clinical service.

Trial Registration: The study protocol was approved by the Ethical Committee of University of Siena (clinicaltrial.gov # NCT01835821), 'retrospectively registered'.
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http://dx.doi.org/10.1186/s12903-019-0957-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6902521PMC
December 2019

Health Data in Dentistry: An Attempt to Master the Digital Challenge.

Public Health Genomics 2019 7;22(1-2):1-7. Epub 2019 Aug 7.

University Center for Dental Medicine Basel, Department of Reconstructive Dentistry, University of Basel, Basel, Switzerland.

Background: Biomedical research has recently moved through three stages in digital healthcare: (1) data collection; (2) data sharing; and (3) data analytics. With the explosion of stored health data (HD), dental medicine is edging into its fourth stage of digitization using artificial intelligence (AI). This narrative literature review outlines the challenge of managing HD and anticipating the potential of AI in oral healthcare and dental research by summarizing the current literature.

Summary: The basis of successful management of HD is the establishment of a generally accepted data standard that will guide its implementation within electronic health records (EHR) and health information technology ecosystems (HIT Eco). Thereby continuously adapted (self-) learning health systems (LHS) can be created. The HIT Eco of the future will combine (i) the front-end utilization of HD in clinical decision-making by providers using supportive diagnostic tools for patient-centered treatment planning, and (ii) back-end algorithms analyzing the standardized collected data to inform population-based policy decisions about resource allocations and research directions. Cryptographic methods in blockchain enable a safe, more efficient, and effective dental care within a global perspective. Key Message: The interoperability of HD with accessible digital health technologies is the key to deliver value-based dental care and exploit the tremendous potential of AI.
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http://dx.doi.org/10.1159/000501643DOI Listing
January 2020

Posterior partial crowns out of lithium disilicate (LS2) with or without posts: A randomized controlled prospective clinical trial with a 3-year follow up.

J Dent 2019 04 1;83:12-17. Epub 2019 Feb 1.

Department of Reconstructive Dentistry, University Center for Dental Medicine, Basel, Switzerland.

Objectives: The objective of this randomized controlled trial was to assess the influence of use of posts as well as the type of posterior tooth (premolars vs molars) for the treatment with lithium disilicate (LS2) partial crowns.

Materials And Methods: A total of 60 patients were treated with posterior LS2 partial crowns. Two groups (n = 60) were made based on the type of restored tooth: Group 1, premolars and Group 2, molars. The samples of each group were divided into 2 subgroups (n = 30): Subgroup A restored with fiber posts and Subgroup B without them. Clinical and intraoral radiographic examinations were assessed during each recall (6 months and, 1, 2, and 3 years). Kaplan-Meier log-rank test and Cox regression analysis (Pp < 0.05) were applied.

Results: Three subgroups showed 100% of survival while group 2 A exhibited the lowest performance (93.3%). The Cox regression analysis showed that the presence of the post was not a significant factor for survival time (Hazard Ratio HR = 0388; CI95% Confidence Interval for H R = 0,1- to 1,5; pp = 017). Tooth type had an influence on survival time that was at the limit of statistical significance (Hazard Ratio HR = 0123; CI95% Confidence Interval for HR = 0 0015- to 0997; p = 005). Particularly, failure risk was greater for premolars. 'Post by tooth type' interactions were not statistically significant (p = 0126).

Conclusions: over a 3-year observation period, the clinical performance of endodontically treated teeth restored with lithium disilicate partial crowns was not significantly affected by the use of a fiber post and by the type of tooth (premolars or molars).
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http://dx.doi.org/10.1016/j.jdent.2019.01.004DOI Listing
April 2019

Population-Based Linkage of Big Data in Dental Research.

Int J Environ Res Public Health 2018 10 25;15(11). Epub 2018 Oct 25.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, 4056 Basel, Switzerland.

Population-based linkage of patient-level information opens new strategies for dental research to identify unknown correlations of diseases, prognostic factors, novel treatment concepts and evaluate healthcare systems. As clinical trials have become more complex and inefficient, register-based controlled (clinical) trials (RC(C)T) are a promising approach in dental research. RC(C)Ts provide comprehensive information on hard-to-reach populations, allow observations with minimal loss to follow-up, but require large sample sizes with generating high level of external validity. Collecting data is only valuable if this is done systematically according to harmonized and inter-linkable standards involving a universally accepted general patient consent. Secure data anonymization is crucial, but potential re-identification of individuals poses several challenges. Population-based linkage of big data is a game changer for epidemiological surveys in Public Health and will play a predominant role in future dental research by influencing healthcare services, research, education, biotechnology, insurance, social policy and governmental affairs.
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http://dx.doi.org/10.3390/ijerph15112357DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6265733PMC
October 2018

CAD/CAM implant crowns in a digital workflow: Five-year follow-up of a prospective clinical trial.

Clin Implant Dent Relat Res 2019 Feb 26;21(1):169-174. Epub 2018 Oct 26.

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel, University of Basel, Basel, Switzerland.

Background: Implant restorations became the first choice for single-tooth replacement today.

Purpose: The prospective clinical trial aims to investigate computer-aided-design (CAD)/computer-aided-manufacturing (CAM)-processed implant crowns after 5 years of loading.

Materials And Methods: Twenty patients were included for cement-retained crowns in posterior sites. Radiographic analysis of bone levels was performed after delivery and follow-up. The Functional Implant Prosthodontic Score (FIPS) was assessed at the final follow-up. Wilcoxon signed-rank tests were used with a level of significance set at α = 0.05.

Results: One implant was lost, resulting in a success rate of 95% at 5 years. For 19 crowns, neither technical complications nor biological complications were observed. The mean marginal bone level was 0.6 ± 0.26 mm (range: 0.18-1.12) mesially, and 0.79 ± 0.36 mm (range: 0.23-1.36) distally at 5 years. During the observation period, mean radiographic bone levels increased significantly by 0.23 mm at mesial and by 0.17 mm at distal sites (P < .0001) indicating minor additional bone loss. The mean total FIPS score was 8.2 ± 1.0 (range: 7-10) with the high score of 2.0 ± 0.0 for the variable "bone."

Conclusions: CAD/CAM-processed implant crowns demonstrated promising radiographic and clinical outcomes after 5 years in function. Future large-scale trials are crucial to confirm these initial results in the field of digital implant processing.
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http://dx.doi.org/10.1111/cid.12681DOI Listing
February 2019

The ability of marginal detection using different intraoral scanning systems: A pilot randomized controlled trial.

Am J Dent 2018 Oct;31(5):272-276

Department of Reconstructive Dentistry, University Center for Dental Medicine Basel UZB, Switzerland.

Purpose: To assess the clinical ability of marginal detection of different intraoral optical scanning (IOS) systems.

Methods: The Ethics Committee of the University of Siena, Italy approved the research project. Thirty patients in need of an onlay/inlay with supra-gingival margins were included and randomly divided in three groups of 10 (3× n=10) according to the IOS for chairside capturing:(A) GC-Europe (Aadva); (B) True-Definition-TD; (C) Trios. A total of 1 scans from each IOS test group (A-C), were obtained clinically and stored as STL-files. In addition, corresponding conventional impressions were taken for all 30 patients, poured with stone, and then processed by a laboratory scanner (Aadva), serving as controls. All 60 STL-files were imported to the Exocad platform for analysis. The horizontal distance between each preparation margin and the adjacent tooth was measured using the ruler tool in the software. The distance at which the detection of the margin started to become visibly unclear was recorded for the horizontal distances. Data was processed statistically by one-way ANOVA (P> 0.05).

Results: No statistically significant inter-test group differences could be identified (IOS A-C). The minimum distance from which a clear margin was visible, was 4.5 (SD 0.1) mm for all images, regardless of which IOS was used. Under these experimental clinical conditions, all tested IOS performed similarly. In contrast, all margins of the controls were clearly visible.

Clinical Significance: None of the tested intraoral scanning systems in this study were capable of recording a clear impression when the cervical margin for a posterior partial crown was located at a distance of less than 0.5 mm from the interproximal neighbor.
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October 2018