Showing papers by "Daniel Edelhoff published in 2016"

A new method for the evaluation of the accuracy of full-arch digital impressions in vitro

Abstract: Introducing a new approach to evaluate the accuracy of digital impression methods for full-arch scans, avoiding “best-fit alignment.” A lower jaw model with a straight metal bar between the second molars of both quadrants was directly digitized using an intraoral scanner (True Definition, TRD, n = 12) and indirectly digitized (D810, CON, n = 12) after impression and plaster cast. A dataset of the bar from a coordinate measuring machine served as reference (REF). Datasets obtained from test groups were analyzed using inspection software to determine the aberration of the bar length, the linear shift (in X-, Y-, Z-axis) and the angle deviation (α overall, α coronal, α horizontal) caused by the digitalization method. Mann–Whitney U and unpaired two-sample Student’s t test were implemented to detect differences. The level of significance was set at 5 %. Concerning the bar length, no significant differences were found between groups. In view of the linear shift, CON showed significantly higher values than TRD in Y-axis (p = 0.003) and in Z-axis (p = 0.040). Regarding the angle measurement, TRD showed significant smaller values than CON for α overall (p = 0.006) and for α coronal (p = 0.005). This in vitro study shows that intraoral scanning systems seem to show the same or even higher accuracy than the conventional impression with subsequent indirect digitalization. Intraoral scanners have proven excellent accuracy for single teeth or small spans. However, insufficient data is available about their accuracy for full-arch scans. The presented new approach seems to be suitable to precisely analyze differences in the accuracy of different digitalization methods without using best-fit alignment.

Composite Resin Core Buildups With and Without Post for the Restoration of Endodontically Treated Molars Without Ferrule

Abstract: Clinical Relevance When restoring endodontically treated molars without ferrule, the use of a post must be questioned and may be substituted by the selection of improved buildup materials.

Bonding between CAD/CAM resin and resin composite cements dependent on bonding agents: three different in vitro test methods

Abstract: Objectives The aim of this study was to assess the bonding properties between CAD/CAM resin and three resin composite cements combined with different bonding agents using three test methods.

Minimally invasive treatment options in fixed prosthodontics.

Abstract: Minimally invasive treatment options have become increasingly feasible in restorative dentistry, due to the introduction of the adhesive technique in combination with restorative materials featuring translucent properties similar to those of natural teeth. Mechanical anchoring of restorations via conventional cementation represents a predominantly subtractive treatment approach that is gradually being superseded by a primarily defect-oriented additive method in prosthodontics. Modifications of conventional treatment procedures have led to the development of an economical approach to the removal of healthy tooth structure. This is possible because the planned treatment outcome is defined in a wax-up before the treatment is commenced and this wax-up is subsequently used as a reference during tooth preparation. Similarly, resin- bonded FDPs and implants have made it possible to preserve the natural tooth structure of potential abutment teeth. This report describes a number of clinical cases to demonstrate the principles of modern prosthetic treatment strategies and discusses these approaches in the context of minimally invasive prosthetic dentistry.

Influence of Specimen Preparation and Test Methods on the Flexural Strength Results of Monolithic Zirconia Materials

Abstract: The aim of this work was to evaluate the influence of specimen preparation and test method on the flexural strength results of monolithic zirconia. Different monolithic zirconia materials (Ceramill Zolid (Amann Girrbach, Koblach, Austria), Zenostar ZrTranslucent (Wieland Dental, Pforzheim, Germany), and DD Bio zx² (Dental Direkt, Spenge, Germany)) were tested with three different methods: 3-point, 4-point, and biaxial flexural strength. Additionally, different specimen preparation methods were applied: either dry polishing before sintering or wet polishing after sintering. Each subgroup included 40 specimens. The surface roughness was assessed using scanning electron microscopy (SEM) and a profilometer whereas monoclinic phase transformation was investigated with X-ray diffraction. The data were analyzed using a three-way Analysis of Variance (ANOVA) with respect to the three factors: zirconia, specimen preparation, and test method. One-way ANOVA was conducted for the test method and zirconia factors within the combination of two other factors. A 2-parameter Weibull distribution assumption was applied to analyze the reliability under different testing conditions. In general, values measured using the 4-point test method presented the lowest flexural strength values. The flexural strength findings can be grouped in the following order: 4-point < 3-point < biaxial. Specimens prepared after sintering showed significantly higher flexural strength values than prepared before sintering. The Weibull moduli ranged from 5.1 to 16.5. Specimens polished before sintering showed higher surface roughness values than specimens polished after sintering. In contrast, no strong impact of the polishing procedures on the monoclinic surface layer was observed. No impact of zirconia material on flexural strength was found. The test method and the preparation method significantly influenced the flexural strength values.

Histo-anatomic 3D printing of dental structures

Abstract: The creation of dental restorations with natural appearance and biomechanics represents a major challenge for the restorative team The manufacturing-process of high-aesthetic restorations from tooth-coloured restorative materials is currently dominated by manual manufacturing procedures and the outcome is highly dependent on the knowledge and skills of the performing dental technician On the other hand, due to the simplicity of the manufacturing process, CAD/CAM restorations from different material classes gain more and more acceptance in the daily routine Multi-layered restorations show significant aesthetic advantages versus monolithic ones, but are difficult to fabricate using digital technologies The key element for the successful automated digital fabrication of aesthetic anterior restorations seems to be the form of the individual dentine core as defined by dentine enamel junction (DEJ) covered by a more transparent layer of material imitating the enamel layer to create the outer enamel surface (OES) This article describes the possibilities and technologies available for so-called '4D-printing' It introduces the digital manufacturing process of multilayered anterior teeth using 3D multipart printing, taking the example of manufacturing replicas of extracted intact natural teeth

Implant Impression Techniques for the Edentulous Jaw: A Summary of Three Studies

Abstract: PurposePrecise implant-supported restorations require accurate impressions. Transfer, pick-up, and splinted pick-up are commonly used techniques. Several in vitro studies have compared these impression techniques;however, all studies used mechanical evaluation methods. The purpose of this study was to compare the discrepancies of these impression techniques digitally in vitro and in vivo. Materials and MethodsFour dental implants were inserted in ten polymer mandibular models bilaterally in the regions of the first molars and canines. Three different impressions were made of each model and the models (original and stone casts) were scanned and digitized. Clinically, four implants were inserted in ten edentulous jaws;transfer and splinted pick-up impressions were made. With inspection software, discrepancies between the different impressions were calculated. ResultsThe mean discrepancies in the in vitro study of the original polymer model to stone casts were 124 34 m for the transfer type, 116 +/- 46 m for the pick-up type, and 80 +/- 25 m for the splinted pick-up type, resulting in a mean discrepancy between the transfer and splinted pick-up type of 44 m (124 - 80 m). Clinically, the mean discrepancy between these two impression techniques was 280 m. ConclusionsThe differing results between the transfer and splinted pick-up techniques of in vitro and in vivo data showed the need for clinical data;however, splinted pick-up impressions seemed to produce the most precise results.

Flexural Strength of Preheated Resin Composites and Bonding Properties to Glass-Ceramic and Dentin

Abstract: To test the impact of preheating (25, 37, 54, or 68 °C) of TetricEvoCeram (TEC), FiltekSupremeXT (FSXT), and Venus (V) on flexural strength (FS), shear bond strength (SBS) and interfacial tension (IFT). FS was tested with TEC and FSXT. For SBS, glass-ceramic and human dentin substrate were fabricated and luted with the preheated resin composite (RC). SBSs of 1500 thermal cycled specimens were measured. For IFT, glass slides covered with the non-polymerized RC were prepared and contact angles were measured. Data were analyzed using 2/1-way ANOVA with Scheffe-test, and t-test (p < 0.05). Preheated TEC (37-68 °C) showed higher FS compared to the control-group (25 °C) (p < 0.001). FSXT presented higher FS than TEC (p < 0.001). For SBS to dentin higher values for FSXT than TEC were found. The preheating temperature showed no impact on SBS to dentin. SBS to glass-ceramic revealed a positive influence of temperature for TEC 25-68 °C (p = 0.015). TEC showed higher values than V and FSXT (p < 0.001). IFT values increased with the preheating temperature. A significant difference could be observed in every RC group between 25 and 68 °C (p < 0.001).

Comparison of fracture loads of CAD/CAM and conventionally fabricated temporary fixed dental prostheses after different aging regimens.

Abstract: This study evaluated the fracture loads of different threeunit fixed dental prostheses (FDPs) for temporary restorations In total, three CAD/CAM materials (VITA CADTemp [CT], Telio CAD [TC], and ZENO ProFix [ZP]) and two chairside materials (Protemp 4 [PT], and Dentalon Plus [DP]) were used for the fabrication of the FDPs Sixteen FDPs were fabricated from each material in an anatomical shape and stored in 09% NaCl solution at 37°C for 14 days Thereafter, one half of the specimens from each group (n = 8) were additionally mechanically and thermally loaded (240,000 chewing cycles, 50 N, 5°/55°C, 2,100 thermal cycles) Fracture loads were measured and data analyzed using two- and one-way ANOVA, followed by Scheffe's post hoc test ZP showed the highest mean fracture loads, regardless of the aging regime Significantly lowest values were identified for DP and TC within the non-thermal loaded group, and for PT and CT within the thermal loaded group No negative impact of aging regimes could be observed

[Dental biocorrosions - etiology, diagnostic, prevention and treatment options].

Abstract: Der Zahn der Zeit nagt auch am Gebiss. Je alter wir werden, desto groser ist der mechanische Verschleis. Doch auch jungere Patienten und sogar Kinder sind schon betroffen, z. B. durch ubermasigen Konsum saurehaltiger Softdrinks. Wie kann die Biokorrosion aufgehalten werden? Welche restaurativen Moglichkeiten gibt es bei weit fortgeschrittenen Stadien?

Current aspects of senior dentistry

Abstract: Im Vergleich zu fruher haben heute immer mehr altere Menschen in Deutschland noch ihre eigenen Zahne Somit sind sie bis ins hohe Alter anfallig fur Karies und Parodontalerkrankungen, insbesondere, wenn sie pflegebedurftig werden Um Folgeerkrankungen und Mangelernahrung zu verhindern, lohnt der regelmasige Blick in den Mund dieser Patienten