Publications by authors named "Jan-Frederik Güth"

70 Publications

Effects of porcelain veneering methods on conformity of the marginal and internal fit of three-unit zirconia framework.

Odontology 2021 Mar 23. Epub 2021 Mar 23.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany.

The purpose of this study is to investigate the effects of porcelain veneering methods on the marginal and internal fit of a three-unit zirconia framework. A zirconia master model, in which the lower-left second premolar and the second left molar were used as the abutment, was obtained using an intraoral scanner. Based on the data, three-unit zirconia frameworks for fabricating all-ceramic bridges were designed and milled (FW group). Two types of all-ceramic bridge were fabricated by veneering porcelain onto these frameworks using the press-over technique (P group) and the layering technique (L group). The replica technique was used to measure the gap size between the abutments and the bridges. Measurements were taken in the marginal opening area (MO), chamfer area (CH), axial area (AX), and occlusal area (OC). Statistical analysis was performed using the Mann-Whitney U-test. There was no significant difference in MO and CH between the P and L groups. However, in AX, the L group had a significantly larger gap size than that of the P group (p = 0.003). In addition, compared with the FW group, the P group showed a significantly larger gap size in MO (p < 0.000), CH (p = 0.008), and OC (p < 0.000). These results indicate that the gap size increased after porcelain veneering using the press-over and layering techniques. In addition, the all-ceramic bridges fabricated using the press-over and layering techniques had approximately equal gap sizes in MO.
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http://dx.doi.org/10.1007/s10266-021-00595-3DOI Listing
March 2021

Ball versus Locator Attachments: A Retrospective Study on Prosthetic Maintenance and Effect on Oral-Health-Related Quality of Life.

Materials (Basel) 2021 Feb 23;14(4). Epub 2021 Feb 23.

Department of Prosthodontics, Julius Maximilian University Würzburg, Pleicherwall 2, 97070 Würzburg, Germany.

Locator and ball attachments are well-established systems to attach overdentures to two inter-foraminal implants. This study aimed to evaluate differences between the two systems regarding prosthetic maintenance and patients' oral-health-related quality of life (OHRQoL). Dental records of patients with a mandibular implant-retained overdenture were retrospectively analyzed. Prosthetic maintenance measures involving the denture suprastructure and attachment matrix and patrix were analyzed. Furthermore, the Oral Health Impact Profile-G14 (OHIP-G14) was used to evaluate OHRQoL. Results were analyzed by means of Kaplan-Meier analysis and Student's - and log-rank tests. The records of 122 patients were evaluated. Kaplan-Meier survival analysis revealed a significant difference between ball attachments (Group B; patients = 47) and Locator attachments (Group L; patients = 75) regarding the occurrence of denture fractures ( < 0.001) and events affecting the matrix ( = 0.028) and patrix ( = 0.030). Group L had a significantly lower total OHIP-G14 score than Group B ( = 0.002). The most common maintenance events were matrix-related and denture relining for both attachment systems. Group B required more maintenance measures than Group L. Moreover, patients in Group L had better OHRQoL than patients in Group B.
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http://dx.doi.org/10.3390/ma14041051DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7926925PMC
February 2021

Short communication: In vitro pilot study: Are monolithic 3Y-TZP zirconia crowns too strong for titanium Implants?

Int J Prosthodont 2021 Mar 3. Epub 2021 Mar 3.

Purpose: To report on pilot tests for a planned study on single implant-supported crowns made from different restorative materials using finite element analysis (FEA) and in vitro load-to-failure testing.

Materials And Methods: Within this pilot study, FEA was conducted using Ansys 2019 R2 to simulate stress and deformation for implant-supported crowns made of lithium disilicate ceramic (LiS2) and zirconia (3Y-TZP). Additionally, an in vitro load to failure test was conducted using two specimens per group to evaluate the failure mode and to confirm the findings from the FEA.

Results/conclusion: FEA revealed stress areas at the palatal cervical areas of the crowns. In the load to failure test, both hybrid abutment crowns made of LiS2 fractured (410 N and 510 N) before plastic deformation of the metal implant components occurred. The monolithic hybrid abutment crowns made of 3Y-TZP did not fracture until tests were interrupted at 646-N and 690-N occlusal force, when plastic deformation of the metal implant components was visually observed.
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http://dx.doi.org/10.11607/ijp.7322DOI Listing
March 2021

Elution behavior of a 3D-printed, milled and conventional resin-based occlusal splint material.

Dent Mater 2021 04 27;37(4):701-710. Epub 2021 Feb 27.

Department of Conservative Dentistry and Periodontology, University Hospital, LMU Munich, Germany; Walther Straub Institute of Pharmacology and Toxicology, Faculty of Medicine, LMU Munich, Germany.

Objective: The elution of unpolymerized (co-)monomers and additives from methacrylic resin-based materials like polymethyl methacrylate (PMMA) can cause adverse side effects, such as mutagenicity, teratogenicity, genotoxicity, cytotoxicity and estrogenic activity. The aim of this study was to quantify the release and the cytotoxicity of residual (co-)monomers and additives from PMMA-based splint materials under consideration of real splint sizes. Three different materials used for additive (3D printing), subtractive (milling) and conventional (powder and liquid) manufacturing were examined.

Methods: The splint materials SHERAprint-ortho plus (additive), SHERAeco-disc PM20 (subtractive) and SHERAORTHOMER (conventional) were analysed. 16 (n = 4) sample discs of each material (6 mm diameter and 2 mm height) were polished on the circular and one cross-section area and then eluted in both distilled water and methanol. The discs were incubated at 37 °C for 24 h or 72 h and subsequently analysed by gas chromatography/mass spectrometry (GC/MS) for specifying and quantifying released compounds. XTT-based cell viability assays with human gingival fibroblasts (HGFs) were performed for Tetrahydrofurfuryl methacrylate (THFMA), 1,4-Butylene glycol dimethacrylate (BDDMA) and Tripropylenglycol diacrylate (TPGDA). In order to project the disc size to actual splint sizes in a worst-case scenario, lower and upper jaw occlusal splints were designed and volumes and surfaces were measured.

Results: For SHERAeco-disc PM20 and for SHERAORTHOMER no elution was determined in water. SHERAprint-ortho plus eluted the highest THFMA concentration of 7.47 μmol/l ±2,77 μmol/l after 72 h in water. Six (co-)monomers and five additives were detected in the methanol eluates of all three materials tested. The XTT-based cell viability assays resulted in a EC of 3006 ± 408 μmol/l for THFMA, 2569.5 ± 308 μmol/l for BDDMA and 596.7 ± 88 μmol/l for TPGDA.

Significance: With the solvent methanol, released components from the investigated splint materials exceeded cytotoxic concentrations in HGFs calculated for a worst-case scenario in splint size. In the water eluates only the methacrylate THFMA could be determined from SHERAprint-ortho plus in concentrations below cytotoxic levels in HGFs.
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http://dx.doi.org/10.1016/j.dental.2021.01.024DOI Listing
April 2021

Two-body wear and fracture behaviour of an experimental paediatric composite crown in comparison to zirconia and stainless steel crowns dependent on the cementation mode.

Dent Mater 2021 02 6;37(2):264-271. Epub 2020 Dec 6.

Department of Conservative Dentistry and Periodontology, University Hospital, Ludwig-Maximilians University Munich, Germany.

Objectives: The purpose of this in vitro study was to assess the two-body wear and fracture behaviour of an experimental additive manufactured composite crown in comparison to zirconia and stainless steel crowns and its cementation protocol for primary molars.

Material And Methods: Three different paediatric crowns - experimental composite crowns (CCs, 3M), zirconia crowns (ZCs, NuSmile), and stainless steel crowns (SSCs, 3M)-were cemented with an experimental resin-modified glass ionomer cement (RMGIC, 3M) and two self-adhesive cements (SACs; RelyX Unicem Automix 2, 3M; BioCem, NuSmile). Seven groups, each with eight specimens, were thermally cycled (55 °C/50 °C) and dynamically loaded (50N/ 1.2Hz) in a masticatory simulator with steatite antagonists. The areal and volumetric material loss of all specimens before and after 1,200,000 masticatory cycles was evaluated with a 3D profilometer. Light and scanning electron microscopy were used for qualitative analysis. Pairwise comparisons between all the groups were performed using the Mann-Whitney U test (p < 0.05).

Results: Microscopic imaging revealed different wear patterns for each material. Lowest fracture rates were documented for the CCs. In contrast, all the SSCs showed perforations. The CCs cemented with RMGIC showed the highest significant volumetric wear (6.3 ± 0.72 mm³), followed by the SSCs cemented with RMGIC (3.6 ± 1.79 mm³) and CCs cemented with SAC (3.5 ± 1.92 mm³). No significant differences were found in terms of the wear among all the other groups, ranging between 0.4 ± 0.25 and 0.6 ± 0.32 mm³.

Conclusion: The volume loss of the tested crowns differed for each material and was dependent on the type of cementation. With regard to in vitro wear and fracture patterns, cementation with SAC may increase the clinical performance of CC paediatric crowns.
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http://dx.doi.org/10.1016/j.dental.2020.11.010DOI Listing
February 2021

Marginal and internal fit of three-unit fixed dental prostheses fabricated from translucent multicolored zirconia: Framework versus complete contour design.

J Prosthet Dent 2021 Feb 14;125(2):340.e1-340.e6. Epub 2020 Nov 14.

Professor, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany.

Statement Of Problem: Translucent multicolored zirconia materials enable more esthetic complete contour zirconia fixed dental prostheses (FDPs) than conventional zirconia, which exhibits low translucency and high opacity and is monochromatic. However, how the marginal and internal fit of translucent multicolored zirconia FDPs compare with those of traditional frameworks that require veneering is unclear.

Purpose: The purpose of this in vitro study was to compare the marginal and internal fit of frameworks and complete contour 3-unit FDPs fabricated from translucent multicolored zirconia.

Material And Methods: Frameworks with a thickness of 0.5 mm and complete contour FDPs with a thickness of 0.8 to 1.5 mm were manufactured by using a workflow similar to one from a zirconia master model (mandibular left second premolar-mandibular left second molar). Two polyvinyl siloxane replicas were made for each specimen to measure the marginal and internal fit. Measurement locations were mesial, lingual, buccal, and distal for each abutment. In these locations, the marginal opening (MO), chamfer area (CA), axial wall (AW), and occlusal area (OC) were measured. The data were analyzed with 2-way ANOVA and the Bonferroni post hoc test (α=.05).

Results: Frameworks showed significantly better mean ±standard deviation fit values than complete contour 3-unit FDPs at measurement areas MO (frameworks: 112 ±22 μm, complete contour FDPs: 144 ±37 μm) (P=.013), CA (frameworks: 89 ±12 μm, complete contour FDPs: 110 ±22 μm) (P=.006), and OC (frameworks: 182 ±36 μm, complete contour FDPs: 244 ±64 μm) (P=.008). At the measurement area AW (frameworks: 47 ±7 μm, complete contour FDPs: 50 ±9 μm of each location, no significant difference was observed between frameworks and complete contour FDPs (P=.361).

Conclusions: Design differences in 3-unit FDPs fabricated from translucent multicolored zirconia influenced the marginal and internal fit. Frameworks had smaller marginal fit than complete contour FDPs for translucent multicolored zirconia.
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http://dx.doi.org/10.1016/j.prosdent.2020.08.023DOI Listing
February 2021

Double crown rescue concept: clinical and dental technical workflow.

Int J Comput Dent 2020 ;23(3):281-292

For decades, double crowns in different variations have proven to be reliable attachments in removable prosthetics. Supported by teeth and implants, they provide proper retention, a considerable degree of chewing comfort, and satisfying esthetics. A wide range of applications, optimal oral hygiene capabilities, and almost unlimited expandability are just some of the advantages of double crown anchored dentures. Among other things, abutment tooth loss is a frequent complication. If an abutment tooth is lost, the secondary crown is usually filled with resin and the denture can continue to be used. However, since the loss of one or more abutment teeth changes biomechanical load ratios, a decline in stability and comfort is likely to occur as well as overloading of the remaining abutment teeth. The concept presented in this article provides for the application of computer-assisted technologies that enable the preservation of the denture according to its original design. For this purpose, a lost or hopelessly decayed tooth is replaced with an implant using digital preplanning and guided implant surgery. The original primary crown is then reattached in its exact former position applying a CAD/CAM-fabricated meso-abutment. In effect, the number of abutment teeth can be preserved, the functionality of the denture maintained with reasonable effort, and further damage prevented.
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August 2020

Accuracy of data obtained from impression scans and cast scans using different impression materials.

Int J Comput Dent 2020 ;23(2):129-138

Aim: Despite the expanding implementation of intraoral scanning (IOS) devices, indirect digitization of conventional impressions or casts still represents the primary access to CAD/CAM. The aim of this study was to evaluate the accuracy of data acquired from impression scans and cast scans with respect to impression material and type of cast used.

Materials And Methods: A standardized titanium model for a four-unit fixed dental prosthesis (FDP) served as a testing model. Industrial computed tomography (CT) was applied, generating a reference data set. Four different impression materials were utilized (n = 12 per material): 1) Impregum Penta (polyether/group PE); 2) Imprint 4 Penta Super Quick Heavy + Super Quick Light (polyvinyl siloxane (PVS)/group PVS-I); 3) Dimension Penta H Quick + L (PVS/group PVS-D); and 4) Imprint 4 Preliminary Penta Super Quick (PVS/group PVS-P). Data were obtained from three different model situations, ie, impressions (group IMP), unsectioned plaster casts (group UNSEC), and sectioned casts (group SEC). The surfaces were digitized three times each using a laboratory scanner. The resulting test data were superposed with the reference data using a best-fit algorithm to evaluate accuracy. Statistical analysis was conducted using the Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney tests (level of significance: P < 0.050).

Results: Imprint 4 Penta presented the highest overall accuracy, while Imprint 4 Preliminary Penta Super Quick displayed the poorest results. Regarding the model situation (impression scan vs cast scan), impression scans from Impregum Penta and Imprint 4 Penta showed superior results.

Conclusion: Impression scans in combination with high-precision impression material results in the most accurate data.
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June 2020

Influence of intraoral scanning on the quality of preparations for all-ceramic single crowns.

Clin Oral Investig 2020 Dec 20;24(12):4511-4518. Epub 2020 May 20.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany.

Objectives: To evaluate the influence of intraoral scanning on the quality of preparations for all-ceramic single crowns.

Material And Methods: A total of 690 randomly selected and anonymized in vivo single crown preparations were examined. Three hundred twenty-three preparations were directly recorded with an intraoral scanner (group IS). Data from plaster casts digitized by a laboratory scanner (group ID; N = 367) served as control. Comparisons included convergence angle, marginal design, marginal substance reduction, homogeneity of the finish line, and undercuts. Evaluation was performed using fully automated specialized software. Data were analyzed applying Kolmogorov-Smirnov, Mann-Whitney U test, and Fisher's exact test. Level of significance was set at p < 0.05.

Results: Convergence angle was above optimum in both groups, but significantly larger for group IS (p < 0.001). Marginal design was more ideal in group IS concerning the absence of featheredge design (p < 0.001) and reverse bevel (p = 0.211). Marginal substance reduction was closer to prerequisites for all-ceramic restorations in group IS (p < 0.001). Finish lines were more homogeneous in group IS regarding the uniformity of their course (p < 0.001). Undercuts were more frequently found in group ID than in group IS (p < 0.001).

Conclusions: Intraoral scanning of prepared teeth has positive impact on the quality of preparations for all-ceramic single crowns regarding marginal substance reduction, marginal design, homogeneity of the finish line, and undercuts.

Clinical Relevance: Accurate preparation design represents a fundamental condition for success of ceramic crowns. Since there is potential for optimization, intraoral scanning might enhance preparation quality providing instant visual feedback.
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http://dx.doi.org/10.1007/s00784-020-03316-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7666666PMC
December 2020

Impact of fabrication procedures on residual monomer elution of conventional polymethyl methacrylate (PMMA)-a measurement approach by UV/Vis spectrophotometry.

Clin Oral Investig 2020 Dec 18;24(12):4519-4530. Epub 2020 May 18.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany.

Objectives: To analyse the residual monomer (MMA) elution of polymethyl methacrylate (PMMA) in distilled water after diverse fabrication methods and aging procedures.

Materials And Methods: PMMA specimens (N = 192, PalaXpress; Kulzer, Hanau, Germany) were manufactured (pouring, n = 96/injection, n = 96) and polymerized in water (55°C) without pressure (n = 48) and with 2 bar pressure (n = 48). Specimens were grinded (n = 24) or polished (n = 24) and aged for 12 h in distilled water/37°C (n = 12) or at air/20°C (n = 12) and stored afterwards in distilled water at 37°C. MMA elution was evaluated after 1, 2, 3, 4, 5, 6, 7, 10, 15 days (UV/Vis spectrophotometry). Data were analysed with Kolmogorov-Smirnov, Mann-Whitney-U and Cohen-d test using SPSS (α < 0.5).

Results: The pouring procedure resulted in significantly higher MMA elution than the injection procedure up to 5 days. Polymerization with a pressure of 2 bar reduced the MMA elution significantly for poured specimens. Polishing reduced the MMA elution in comparison to grinding.

Conclusions: The fabrication procedure (pouring/injection) showed the strongest correlation to the MMA elution (r = 0.500), followed by polishing (r = 0.243), the pressure during polymerization (r = 0.109) and the storage medium (r = 0.053).

Clinical Relevance: Higher MMA elution may increase the risk of chemical irritations, allergic reactions and hypersensitivities of the oral mucosa. Technicians and dentists should be aware about the elution differences dependent on the fabrication procedure.
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http://dx.doi.org/10.1007/s00784-020-03317-1DOI Listing
December 2020

In vivo wear of CAD-CAM composite versus lithium disilicate full coverage first-molar restorations: a pilot study over 2 years.

Clin Oral Investig 2020 Dec 12;24(12):4301-4311. Epub 2020 May 12.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336, Munich, Germany.

Objectives: To present a digital approach to measure and compare material wear behavior of antagonistic first molar restorations made of an experimental CAD/CAM composite (COMP) and lithium disilicate ceramic (LS2) in patients with reconstructed vertical dimension of occlusion (VDO) after generalized hard tissue loss.

Methods: A total of 12 patients underwent complete full jaw rehabilitation with full occlusal coverage restorations made either of COMP or LS2. The first molar restorations (n = 48) were chosen for wear examination. At annual recall appointments, polyether impressions were taken, and resulting plaster casts were digitalized using a laboratory scanner. Mean observation period was 371 days for first and 769 days for second year. The resulting 96 datasets were analyzed by superimposition of 3-D datasets using an iterative best-fit method. Based on the superimposition data, the wear rates of the occlusal contact areas (OCAs) were calculated.

Results: For antagonistic restorations made of COMP, the average wear rate was 24.8 ± 13.3 μm/month, while for LS2, it was 9.5 ± 4.3 μm/month in first year, with significant differences (p < 0.0001) between the materials. In second year, monthly wear rates decreased significantly for both materials: COMP (16.2 ± 10.7 μm/month) and LS2 (5.5 ± 3.3 μm/month). Statistical comparison between wear time showed significant differences for both materials: COMP p < 0.037 and LS2 p < 0.001. A logarithmic fit (COMP R = 0.081; LS2 R = 0.038) of the data was calculated to estimate the wear progression.

Significance: In patients with reconstructed VDO, restorations made of LS2 show a more stable wear behavior than ones out of experimental CAD/CAM composite. In cases of complete rehabilitation, load bearing CAD/CAM-composite restorations should be critically considered for application due to their occlusal wear behavior. However, when choosing a restorative material, not only the functional occlusal stability should be taken into account but also the prospect of minimally invasive treatment with maximum preservation of natural tooth structures.
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http://dx.doi.org/10.1007/s00784-020-03294-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7666668PMC
December 2020

Reproducibility of a magnet-based jaw motion analysis system.

Int J Comput Dent 2020 ;23(1):39-48

Background: The Dental Motion Decoder system (DMS-System) is a medical device based on magnetic field technology that records mandible movements. The data can be used to program an articulator or can be directly processed over a computer-aided design (CAD) interface. The present study aimed to assess the reproducibility of this system in vitro and in vivo.

Material And Methods: Protrusive and laterotrusive movements were simulated in vitro using an articulator (SAM SE) (Group M) and in vivo (Group P) on one test individual. Measurements were carried out in two ways: 1) Measurements were taken after initializing and referencing the system using the reference points (RPs) once, followed by 30 protrusive and laterotrusive movements (M1 and P1); and 2) Thirty individual measurements were recorded using the RPs before each measurement (M2 and P2). Values for the sagittal condylar path inclination angle (sCPIA) and the Bennett angle (BA) were exported and analyzed. The reproducibility of the system was evaluated using the standard deviations (SDs) of the measurement series (sCPIA and BA for M1, M2, P1, and P2).

Results: In vitro tests M1 (SD: sCPIA = 0.08 degrees; BA = 0.06 degrees) and M2 (SD: sCPIA = 0.26 degrees; BA = 0.11 degrees) showed significantly higher reproducibility (P < 0.001) compared with the in vivo measurements P1 (SD: sCPIA = 0.61 degrees; BA = 0.45 degrees) and P2 (SD: sCPIA = 1.4 degrees; BA = 0.65 degrees).

Conclusion: Within the limitations of the present study, the deviation in vitro, representing the reproducibility of the DMD-System, is smaller than the biologic variance observed in vivo. Therefore, reliable measurements under clinical conditions can be assumed.
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March 2020

Influence of speed sintering on the fit and fracture strength of 3-unit monolithic zirconia fixed partial dentures.

J Prosthet Dent 2020 Sep 25;124(3):380-386. Epub 2019 Nov 25.

Assistant Professor, Department of Prosthetic Dentistry, University Hospital, Ludwig Maximilian University of Munich, Munich, Germany. Electronic address:

Statement Of Problem: Speed sintering has been introduced to enable single-visit monolithic zirconia prostheses. However, the fit and fracture load of zirconia 3-unit monolithic fixed partial dentures (FPDs) after speed sintering are unknown.

Purpose: The purpose of this in vitro study was to test the properties of zirconia 3-unit monolithic FPDs after speed sintering and to compare the properties with conventional sintering.

Material And Methods: A calibrated operator digitized an in vitro model with a complete coverage preparation of a maxillary right second premolar and second molar (n=12) by using the CEREC AC Omnicam (Dentsply Sirona) scanner. Twelve zirconia FPDs were designed (CEREC SW 4.1.1), and for each data set (n=12), 1 FPD was designed and milled 4 times (MCXL Premium; CEREC Zirconia; Dentsply Sirona), resulting in 4 identical monolithic FPDs (N=48). The FPDs were divided into 2 groups according to the sintering procedure (n=24): speed sintering (group S) by using the SpeedFire (Dentsply Sirona) and the conventional sintering (group C) by using the inFire HTC speed (Dentsply Sirona). All the FPDs were glazed by using glaze-spray and fired according to the sintering group. The SpeedFire (Dentsply Sirona) was used for group S, and the VACUMAT 6000M (VITA Zahnfabrik) was used for group C. The fit of the FPDs was evaluated with the replica technique by using polyvinyl siloxane and analyzed according to the measurement areas: marginal gap, chamfer area, axial wall, and occlusal area. Subsequently, groups S and C were further subdivided, and 12 specimens per group underwent artificial aging by thermomechanical loading in a mastication machine (50 N for 1.2×10 times at a frequency of 1.7 Hz and a thermal change in distilled water from 5 °C to 50 °C every 120 seconds), resulting in additional subgroups: group SA and group CA. For all the FPDs (groups S, C, SA, and CA), a fracture load measurement was conducted. The Kolmogorov-Smirnov test was used to examine the values of the fit and fracture load for normal distribution. The Mann-Whitney U test for the fit and a 2-way ANOVA for the fracture load were used to detect the differences among the groups (α=.05).

Results: Group S showed a better marginal (P=.018) and occlusal (P<.001) fit than group C. For the fracture load values, no significant difference was found because of the sintering procedure (P=.070) or the interaction of the sintering procedure and artificial aging (P=.484). Artificial aging showed an impact (P=.024) with significantly lower values after aging.

Conclusions: Speed-sintered FPDs had equal and better values for the fit and fracture load than conventional sintering.
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http://dx.doi.org/10.1016/j.prosdent.2019.09.003DOI Listing
September 2020

Internal porosities, retentive force, and survival of cobalt-chromium alloy clasps fabricated by selective laser-sintering.

J Prosthodont Res 2020 Apr 1;64(2):210-216. Epub 2019 Nov 1.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Germany.

Purpose: The purpose of this study was to evaluate internal porosities, retentive force values and survival of cobalt-chromium (Co-Cr) alloy clasps fabricated by direct metal laser-sintering (DMLS) and compare them to conventionally cast clasps.

Methods: Embrasure clasps were digitally designed fitting teeth 35 and 36 on identical metal models (N = 32). Sixteen clasps were fabricated using DMLS (group DMLS) and another sixteen clasps were additively manufactured from wax and then cast from a Co-Cr alloy (group CAST). Internal porosities were examined using micro-focus X-ray (micro-CT) and analyzed applying Kolmogorov-Smirnov test, Mann-Whitney test, and T test (significance level: p < 0.050). A universal testing machine was used to determine the retentive force values at baseline and after 1095, 5475, 10,950 and 65,000 cycles of simulated aging. Data were analyzed employing Kolmogorov-Smirnov test, one-way ANOVA, and Scheffé's post-hoc test (significance level: p < 0.050). Survival was estimated for 65,000 cycles of artificial aging using Kaplan-Meier analysis.

Results: Micro-CT analysis revealed a higher prevalence (p < 0.001), but a more homogeneous size and a significantly smaller mean (p = 0.009) and total volume (p < 0.001) of internal porosities for group DMLS. The groups showed mean initial retentive force values of 13.57 N (CAST) and 15.74 N (DMLS), which significantly declined over aging for group CAST (p = 0.003), but not for group DMLS (p = 0.107). Survival was considerably higher for group DMLS (93.8%) than for group CAST (43.8%) after 65,000 cycles of aging.

Conclusions: Clasps made by laser-sintering could be an alternative to conventional cast clasps for the fabrication of removable partial denture frameworks.
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http://dx.doi.org/10.1016/j.jpor.2019.07.006DOI Listing
April 2020

Mechanical stability of all-ceramic abutments retained with three different screw materials in two-piece zirconia implants-an in vitro study.

Clin Oral Investig 2020 May 3;24(5):1801-1806. Epub 2019 Sep 3.

Department of Prosthodontics, University of Munich, Goethestr 70, 80336, Munich, Germany.

Objectives: To measure the abutment rotation and fracture load of two-piece zirconia implants screwed with three different abutment screw materials.

Material And Methods: Thirty-six zirconia implants with 36 zirconia abutments were distributed into 3 test groups: group G connected with gold screws, group T with titanium screws, and group P with peek screws. In the first part of the study, the rotation angle of the abutments was measured. The second part of the study measured the maximum fracture force of adhesively bonded lithium disilicate crowns after artificial aging and fracture modes were reported.

Results: In group G, the median rotation angle was 8.0°, in group T 11.6°, and in group P 9.5°. After artificial aging, no screw loosening, crown, abutment, or implant fracture occurred. The median fracture force in group G was 250 N, in group T 263 N, and in group P 196 N.

Conclusions: Rotation angles and fracture loads of two-piece zirconia implants with gold, titanium, or peek screws showed no significant differences; however, fracture loads showed inferior results for group P.

Clinical Relevance: The indication for the material peek as an abutment screw is still questionable and should be considered carefully.
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http://dx.doi.org/10.1007/s00784-019-03043-3DOI Listing
May 2020

Digital impressions in dentistry-accuracy of impression digitalisation by desktop scanners.

Clin Oral Investig 2020 Mar 13;24(3):1249-1257. Epub 2019 Jul 13.

Department of Prosthetic Dentistry, University Hospital of the LMU Munich, Goethestraße 70, 80336, Munich, Germany.

Objectives: To test if the partially digital workflow by digitalisation of the impression reveals a comparable accuracy as the indirect digitalisation of the gypsum cast for 4-unit fixed dental prostheses (FDPs).

Materials And Methods: A titanium model with a tapered full veneer preparation of a molar and premolar was used as analysis model. To receive a virtual three-dimensional reference dataset (REF), it was digitised by industrial computed tomography. Three impression materials were used with individual impression trays (N = 36, n/material = 12): (1) PE (Impregum Penta), (2) PVS-I (Imprint 4 Penta: Super Quick Heavy plus Super Quick Light), and (3) PVS-D (Dimension Penta: H Quick plus L). For partially digital workflow (group IMP), two desktop scanners were used: (1) D810 (3Shape D810) and (2) ZZ (Zirkonzahn S600ARTI). For indirect digitalisation (group CAST), gypsum master casts were manufactured and digitalised using the same desktop scanners. Virtual datasets were superimposed by best fit algorithm, and accuracy was analysed by calculating the Euclidean distances (ED) to the REF (Geomagic Qualify). Statistic was determined (Kruskal-Wallis H test, Mann-Whitney U post hoc analysis, two-sample Kolmogorov-Smirnov test, p < 0.05).

Results: ZZ showed for positive deviations superior accuracy for IMP than for CAST. PE and PVS-I showed superior accuracy than PVS-D. D810 showed partially significant better performance with PVS-I and PVS-D than ZZ.

Conclusions: The partially digital workflow by digitalisation of the impression can be used for clinical indications of small-span fixed dental prostheses. However, for this indication, the impression material and the desktop scanner are more decisive for the accuracy of virtual model datasets.

Clinical Relevance: Despite the rapid advancement of the computer-aided technology for dental therapy purposes, the implementation of this technique is not as fast as the technical development. In order to combine the well-established procedure to use elastomeric materials for a conventional impression and to avoid the drawbacks of casting it by gypsum, the digitalisation of the impression itself by a desktop scanner may be a logical procedure as an access point to the digital workflow. However, there is only limited information about the accuracy of this partially digital workflow by the digitalisation of modern impression materials in comparison to the well-known process of indirect digitalisation of gypsum casts.
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http://dx.doi.org/10.1007/s00784-019-02995-wDOI Listing
March 2020

Zirconia and its novel compositions: What do clinicians need to know?

Quintessence Int 2019 ;50(7):512-520

For several years, there has been a clear trend in the dental market towards monolithic tooth-colored restorations. In this context, further developments, particularly in the field of zirconia ceramics, have led to considerable improvement in the materials' optical properties. Modern zirconia materials can be divided into several cohorts, differing from each other with respect to their optical and mechanical properties. The knowledge about indications and limitations of each zirconia cohort is essential for a correct clinical application. Clinical long-term experience for the zirconia of the newest generations is still scarce and only in-vitro data are available. Despite all advancements, clinical long-term success remains closely linked to the specific indications, preparation, material selection, knowledge, and experience of the dental practitioner and dental technician, as well as an adequate luting mode and occlusal concept. Due to the high innovation rate within materials and CAD/CAM technology in general, clinicians and dental technicians need to be well informed in order to be able to work successfully with the various options.
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http://dx.doi.org/10.3290/j.qi.a42653DOI Listing
November 2019

Accuracy of full-arch digital impressions: an in vitro and in vivo comparison.

Clin Oral Investig 2020 Feb 27;24(2):735-745. Epub 2019 May 27.

Department of Prosthodontics, LMU Munich, Goethestraße 70, 80336, Munich, Germany.

Objectives: Comparison of full-arch digital impressions to conventional impressions in vitro and in vivo.

Materials And Methods: A straight metal bar was fixed between the second upper molars as a reference structure in the mouth of a voluntary patient and a corresponding polymer model. The following digitalization methods were applied: (1) the maxilla was digitized in vivo 12 times with the iTero Element (P-SCAN); (2) the maxilla was captured in vivo 12 times by conventional impression and the impression was digitized by a desktop scanner (P-IMP); (3) the impressions were poured and the 12 referring gypsum master-casts were scanned with the same desktop scanner (P-CAST); (4) the polymer model was digitized in vitro 12 times with the iTero Element (M-SCAN); (5) the polymer model was captured in vitro 12 times by conventional impression and the impression was digitized by a desktop scanner (M-IMP); (6) the impressions were poured and the 12 referring gypsum master-casts were scanned with the same desktop scanner (M-CAST). Datasets were exported and metrically analyzed (Geomagic Control X) to determine three-dimensional length aberration and angular distortion versus the reference structure. Mann-Whitney U test was implemented to detect differences (p < 0.05).

Results: For multiple accuracy parameters, P-SCAN and M-SCAN showed similar or superior results compared to the other digitalization methods. The following length deviations were found: M-SCAN (- 55 to 80 μm), M-IMP (110 to 329 μm), M-CAST (88 to 178 μm), P-SCAN (- 67 to 76 μm), P-IMP (125-320 μm), and P-CAST (92-285 μm).

Conclusions: Within the limitations of this study, the iTero-scan seems to be a valid alternative to conventional impressions for full arches.

Clinical Relevance: Intraoral scanners are more and more used in daily routine; however, little is known about their accuracy when it comes to full-arch scans. Under optimum conditions, the direct digitalization using the iTero Element intraoral scanning device results in the same and for single parameters (arch width and arch distortion) even in higher accuracy than the indirect digitalization of the impression or the gypsum cast using a desktop scanner.
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http://dx.doi.org/10.1007/s00784-019-02965-2DOI Listing
February 2020

Advances in materials and concepts in fixed prosthodontics: a selection of possible treatment modalities.

Br Dent J 2019 May;226(10):739-748

Associate Professor, Department of Prosthetic Dentistry, University Hospital, LMU, Munich, Germany.

The introduction of adhesive techniques in combination with translucent restorative materials has greatly influenced treatment concepts in fixed prosthodontics. Modern production technologies offer access to new polymer materials that provide innovative pre-treatment options for complex prosthetic rehabilitations. Additionally, computer-aided design and manufacturing (CAD/CAM) provides access to new ceramic types and thus extends the range of indications for metal-free restorative options. With these developments, important changes of treatment concepts in fixed prosthodontics have occurred which affect the professional life of dental practitioners with a focus on prosthetic dentistry. This article gives an overview of the advances in selected fields of fixed prosthodontics and provides support in material selection for different kinds of indications, from single-tooth restorations to fixed dental prostheses.
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http://dx.doi.org/10.1038/s41415-019-0265-zDOI Listing
May 2019

Residual monomer elution from different conventional and CAD/CAM dental polymers during artificial aging.

Clin Oral Investig 2020 Jan 16;24(1):277-284. Epub 2019 May 16.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestrasse 70, 80336, Munich, Germany.

Objectives: Analyze and quantify the residual monomer elution of nine conventional and CAD/CAM (computer-aided design/computer-aided manufacturing) dental polymers during artificial aging.

Materials And Methods: A total of 360 square-shaped specimens (14 × 12 × 2 ± 0.05 mm) were fabricated from eight CAD/CAM polymer blanks (n = 40): Avadent Base material, Avadent Teeth material, PMMA Multi blank, PMMA Mono blank, Temp Premium, Telio CAD, Ceramill Temp, Shofu Block HC, and conventional polymer PalaXpress. Specimens were aged in distilled water for 60 days at 37 °C and the evaluation of the residual monomer elution was made through UV spectrophotometry. Statistical analysis was carried out in the SPSS software. One-way ANOVA and Scheffé post hoc test were applied (α < 0.05).

Results: Aging time significantly changed the elution in all groups, except for PalaXpress. Statistically significant differences of elution were found between the materials. Shofu Block HC presented the highest, whereas PMMA Multi blank A3 and Mono blank A1 presented the lowest elution after the 60th day of aging.

Conclusions: CAD/CAM dental polymers as well as the conventional polymer PalaXpress eluted residual monomer within aging time. The differences in elution were material-dependent; still, the maximum elution found is below the specified threshold of ISO standard 20795-1.

Clinical Relevance: With the evolution of CAD/CAM technology, material's manufacturers have invested in the development of polymeric materials with higher resistance and stability to produce indirect restorations using CAD/CAM. It is expected that these materials present lower elution of residual monomer than conventional polymers.
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http://dx.doi.org/10.1007/s00784-019-02947-4DOI Listing
January 2020

Metal-free implant-supported single-tooth restorations. Part II: Hybrid abutment crowns and material selection.

Quintessence Int 2019 ;50(4):260-269

In many areas of restorative dentistry, metal-free materials offer an alternative to metal-based restorations while ensuring high levels of biocompatibility and esthetics. Rapidly evolving CAD/CAM technology has significantly expanded the range of materials available, providing access to materials classes and their combinations not previously available within conventional manufacturing, such as zirconia ceramics and hybrid ceramics. In addition, digital methods offer previously unavailable options in diagnostics, greater planning reliability, better material quality through standardization of the manufacturing process, and reproducibility - significant benefits that can be used to advantage, especially in oral implantology. Even though technological progress in the field of metal-free materials has given rise to considerable improvements in their mechanical properties over the decades, their clinical long-term success is still very much dependent on an appropriate indication and proper material selection, on the knowledge and skills of the dental practitioner and dental technician, and on an adequate occlusion concept. The high rate of innovation - both with regard to the materials themselves and to CAD/CAM technology - therefore requires an adequate level of prior knowledge to sensibly and successfully implement the wide range of possibilities. It is becoming more and more puzzling for users to find their way around the many different new techniques and materials. This review article provides an up-to-date overview of the possibilities and limitations of metal-free implant-supported single-tooth restorations. This second part discusses hybrid abutment crowns and materials selection. Resultant treatment concepts are presented and evaluated based on clinical examples.
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http://dx.doi.org/10.3290/j.qi.a42099DOI Listing
November 2019

Metal-free implant-supported single-tooth restorations. Part I: Abutments and cemented crowns.

Quintessence Int 2019 ;50(3):176-184

In many areas of restorative dentistry, metal-free materials offer an alternative to metal-based restorations while ensuring high levels of biocompatibility and esthetics. Rapidly evolving CAD/CAM technology has significantly expanded the range of materials available, providing access to materials classes and their combinations not previously available within conventional manufacturing, such as zirconia ceramics and hybrid ceramics. In addition, digital methods offer previously unavailable options in diagnostics, greater planning reliability, better material quality through standardization of the manufacturing process, and reproducibility - significant benefits that can be used to advantage, especially in oral implantology. Even though technological progress in the field of metal-free materials has given rise to considerable improvements in their mechanical properties over the decades, their clinical long-term success is still very much dependent on an appropriate indication and proper material selection, on the knowledge and skills of the dental practitioner and dental technician, and on an adequate occlusion concept. The high rate of innovation - both with regard to the materials themselves and to CAD/CAM technology - therefore requires an adequate level of prior knowledge to sensibly and successfully implement the wide range of possibilities now open. It is becoming more and more puzzling for users to find their way around the many different new techniques and materials. This review article provides an up-to-date overview of the possibilities and limitations of metal-free implant-supported single-tooth restorations. This first part discusses abutments and cemented crowns. Resultant treatment concepts are presented and evaluated based on clinical examples.
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http://dx.doi.org/10.3290/j.qi.a41906DOI Listing
November 2019

Can lithium disilicate ceramic crowns be fabricated on the basis of CBCT data?

Clin Oral Investig 2019 Oct 6;23(10):3739-3748. Epub 2019 Feb 6.

Department of Prosthodontics, University Hospital, LMU, Munich, Germany.

Objectives: Evaluating the fit of CAD/CAM lithium disilicate ceramic crowns fabricated on basis of direct and indirect digitalization of impressions by CBCT or of dental casts.

Material And Methods: A metal model with a molar chamfer preparation was digitized (n = 12 per group) in four ways: IOS-direct digitalization using an Intra-Oral scanner (CS3600), cone-beam computed tomography scan (CBCT 1)-indirect digitalization of impression (CBCT-CS9300), CBCT 2-indirect digitalization of impression (CBCT-CS8100), and Extra-Oral scanner (EOS)-indirect digitalization of gypsum-cast (CeramillMap400). Accuracy of 3D datasets was evaluated in relation to a reference dataset by best-fit superimposition. Marginal fit of lithium disilicate crowns after grinding was evaluated by replica technique. Significant differences were detected for 3D accuracy by Mann-Whitney U and for fit of crowns by One-way ANOVA followed by Scheffe's post hoc (p = 0.05).

Results: 3D analysis revealed mean positive and negative deviations for the groups IOS (- 0.011 ± 0.007 mm/0.010 ± 0.003 mm), CBCT 1 (- 0.046 ± 0.008 mm/0.093 ± 0.004 mm), CBCT 2 (- 0.049 ± 0.030 mm/0.072 ± 0.015 mm), and EOS (- 0.023 ± 0.007 mm/0.028 ± 0.007 mm). Marginal fit presented the results IOS (0.056 ± 0.022 mm), CBCT 1 (0.096 ± 0.034 mm), CBCT 2 (0.068 ± 0,026 mm), and EOS (0.051 ± 0.017 mm).

Conclusions: The marginal fit of EOS and IOS, IOS and CBCT 2, and CBCT 2 and CBCT 1 showed statistical differences. The marginal fit of CBCT 1 and CBCT 2 is within the range of clinical acceptance; however, it is significant inferior to EOS and IOS.

Clinical Relevance: The use of a CBCT enables clinicians to digitize conventional impressions. Despite presenting results within clinical acceptable levels, the CBCT base method seems to be inferior to Intra-Oral scans or to scanning gypsum models regarding the resulting accuracy and fit.
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http://dx.doi.org/10.1007/s00784-019-02802-6DOI Listing
October 2019

Computable translucency as a function of thickness in a multi-layered zirconia.

J Prosthet Dent 2019 Apr 4;121(4):683-689. Epub 2018 Dec 4.

CDT, Department of Prosthetic Dentistry, University Hospital, LMU Munich, Munich, Germany.

Statement Of Problem: Determining the relationship between variable thicknesses and the translucency of dental ceramics is essential for optimizing esthetics in different clinical situations.

Purpose: The purpose of this in vitro study was to analyze the relationship between layer thickness and translucency of 2 multi-layered monolithic zirconia materials and to develop an equation by which the grade of translucency can be calculated dependent on the materials' layer thicknesses in advance.

Material And Methods: Two semisintered multi-layered zirconia blanks, namely KATANA Zirconia Super Translucent Multi-Layered Disk (Noritake Dental Supply Co, Ltd) and Zirconia Ultra Translucent Multi-Layered Disk (UTML) (Noritake Dental Supply Co, Ltd), were sectioned (N=96) to separate the 4 layers (n=12 per layer): enamel layer, transition layer 1, transition layer 2, body layer. All specimens were sintered in a furnace (M2 Plus; Thermo-Star) at 1500°C for 2 hours and automatically polished under water cooling up to P2400 for the thicknesses of 1.6, 1.3, 1.0, 0.7, and 0.4 mm. Transmittance of visible light was measured using a spectrophotometer (Lambda 35; Perkin Elmer). Data were analyzed using the Kolmogorov-Smirnov, 2-way ANOVA, and Scheffé post hoc tests (α=.01) and curve fitting.

Results: Analyzing the fitting of the values of the 8 material groups to the linear, exponential, and logarithmic curves, 7 of the 8 groups (not UTML body layer) fitted the most (R-square value closer to 1.0) to the logarithmic curve. Constants were obtained from the distance to the x-axis and the curvature.

Conclusions: The methodology of this study provided the materials' specific constants a and b by analyzing the translucency behavior of KATANA Super Translucent Multi-Layered Disk and Ultra Translucent Multi-Layered Disk in different thicknesses, allowing further translucency calculation by applying the developed formula and the constants.
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http://dx.doi.org/10.1016/j.prosdent.2018.08.013DOI Listing
April 2019

Temporary Single Palatal Implant for Denture Stabilization During Augmentation and Implant Procedure: A Case Report.

Int J Periodontics Restorative Dent 2018 Nov/Dec;38(6):e105-e111

This case report introduces a temporary denture with reduced extension stabilized in the edentulous maxilla as a possible treatment method for patients with a severe gag reflex, allowing them to test the function, esthetics, and tolerance of the denture prior to hard tissue augmentation and implant placement. A 4-mm implant was placed in the central anterior palate and allowed to heal for 3 months. During the complete treatment period, a denture with reduced extension can be delivered on a fixed Locator abutment. This method was successfully applied in three patients, and the palatal implant remained stable until the final removable prosthesis could be delivered.
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http://dx.doi.org/10.11607/prd.3600DOI Listing
April 2019

Retentive force of PEEK secondary crowns on zirconia primary crowns over time.

Clin Oral Investig 2019 May 6;23(5):2331-2338. Epub 2018 Oct 6.

Department of Prosthetic Dentistry, University Hospital, LMU Munich, Goethestraße 70, 80336, Munich, Germany.

Objectives: The purpose of the present study was to evaluate the retentive forces of CAD/CAM-fabricated polyetheretherketone (PEEK) secondary crowns on zirconia primary crowns over an artificial aging period representing 10 years of clinical service and compare them to electroformed secondary crowns made from pure gold.

Material And Methods: Implant-supported zirconia primary crowns (N = 20) were CAD/CAM milled and provided either with electroformed secondary crowns (group ZE; N = 10) or CAD/CAM-fabricated PEEK secondary crowns (group ZP; N = 10). All secondary crowns were attached to a casted tertiary structure to ensure adequate stability. A universal testing machine was used to determine the retentive force values at baseline and after 1, 3, 5, and 10 years of simulated aging in the presence of artificial saliva. Data were analyzed applying Kolmogorov-Smirnov, Kruskal-Wallis, and Mann-Whitney U test. Level of significance was set at p < 0.05.

Results: Retentive forces were not different for the groups ZE and ZP at baseline (median ZE 2.85 N; ZP 2.8 N; p ≤ 0.218). Because retentive force values changed significantly over simulation time for group ZE (Kruskal-Wallis; p ≤ 0.028), the values between the test groups ZE and ZP differed significantly (Mann-Whitney U) at 5 years (ZE 3.03 N; ZP 2.76 N; p ≤ 0.003) and 10 years (ZE 3.1 N; ZP 2.78 N; p ≤ 0.011).

Conclusions: PEEK secondary crowns exhibit stable retentive force values over 10 years of simulated aging showing no signs of deterioration while the retentive force values of electroformed secondary crowns increase over time.

Clinical Relevance: PEEK might be a suitable alternative to proven metallic materials for the fabrication of secondary crowns.
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http://dx.doi.org/10.1007/s00784-018-2657-xDOI Listing
May 2019

Transmittance of visible and blue light through zirconia.

Dent Mater J 2018 Sep 12;37(5):812-817. Epub 2018 Jul 12.

Department of Prosthetic Dentistry, Dental School, Ludwig-Maximilians Universität.

The aim of this study was to evaluate the transmittance of visible light (VL) (λ: 400-700 nm) and blue light (BL) (λ: 360-540 nm) through six CAD/CAM zirconia blanks (ZiB) in comparison to a lithium disilicate ceramic (LS2). Disks of the zirconia materials Bruxzir (BX), Cercon (CE), Lava Frame (LF), Lava Plus (LP), Prettau (PT), Zenostar (ZS) and LS2 (EM) were manufactured and the transmittance was measured in a spectrophotometer. ZS, followed by CE, PT, LP, LF, and BX showed the lowest transmittance of VL and BL. The highest transmittance was shown by EM. The transmittance of BL was lower than that of VL in all groups. EM ceramics showed higher transmittance than all zirconia materials and the thickness of zirconia materials influenced the transmittance values. Knowledge about VL and BL transmittance would help clinicians to individually tailor the selection of material to the specific indication and to make the right choice regarding the luting procedure and light curing duration.
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http://dx.doi.org/10.4012/dmj.2016-287DOI Listing
September 2018

Two digital strategies in modern implantology - root-analogue implants and the digital one-abutment/one-time concept.

Int J Comput Dent 2018;21(2):115-131

The irreversible trend toward digitization in dentistry and dental technology has resulted in technical progress and continuous changes to conventional workflows. In particular, implantology and prosthetics have benefited from a multitude of interesting new possibilities. Three-dimensional (3D) computed radiography and digital surface scanning can be invaluable in terms of backward planning and making implant surgery and denture fabrication more predictable. In this context, two digital implant-prosthetic treatment strategies are presented that allow for an efficient digital workflow while ensuring a minimally invasive surgical procedure. By means of digital intraoperative scanning of the implant position, the digital one-abutment/one-time concept allows for the insertion of computer-aided design/computer-aided manufacturing (CAD/CAM)-manufactured single crowns instantly after uncovering the implant. The second approach uses 3D radiographic data to preoperatively manufacture a one-piece root-analogue implant (RAI) and insert it immediately after tooth extraction. Both ideas promise some advantages in terms of quality and preservation of periimplant tissues as well as a noticeable reduction in overall treatment time.
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October 2018

Systematics and concepts for the digital production of complete dentures: risks and opportunities.

Int J Comput Dent 2018;21(1):41-56

The rehabilitation of the edentulous patient with complete dentures is still an essential aspect of dental prosthetics. Modern digital manufacturing technologies have made it possible to produce even complete dentures digitally. This has several advantages, especially regarding the properties of the denture material. In addition, the use of digital technology facilitates new treatment concepts and procedures that reduce the number of appointments needed at the dental office.
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July 2018

Anterior restorations: The performance of ceramic veneers.

Quintessence Int 2018 ;49(2):89-101

Adhesive bonding techniques in combination with tooth-colored restorative materials are one of the greatest achievements of restorative dentistry. Adhesively bonded veneers made from various silicate ceramic materials have contributed significantly to this. Ceramic veneers had long been considered to be only esthetic implements. However, their range of indications has been steadily increasing, making ceramic veneers a highly viable alternative to classic, far more invasive forms of restorative treatment. Today these veneers are used to restore the biomechanics of the dentition, to establish adequate function, to mask highly discolored endodontically treated teeth, and for many other purposes. The present article explains the principles of modern veneer technology based on clinical examples, with special emphasis on collaboration with the dental laboratory and communication within the dental team. This includes analyzing the case, defining the treatment goal, determining the right shade, selecting the most suitable ceramic material, finding the best preparation design, and choosing the most appropriate adhesive concept. The article will also explore the long-term prognosis of ceramic veneers as reported by a number of scientific studies.
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http://dx.doi.org/10.3290/j.qi.a39509DOI Listing
October 2018