Jan-Frederik Güth

Center for Dentistry and Oral medicine (Carolinum) Goethe-University · Department of Prosthodontics

Vor dem Hintergrund der stetig verbesserten Verknüpfung digitaler Technologien in der Zahnmedizin gewinnt die virtuelle Behandlungsplanung in der zahnärztlichen Praxis zunehmend an Bedeutung. Digitale dentale Technologien haben die Art und Weise, wie Zahnärzte und Zahntechniker Patientenbehandlungen durchführen, grundlegend verändert. Das betrifft...

Objective Evaluation of the accuracy of direct digitization of maxillary scans depending on the scanning strategy. Materials and Method A maxillary model with a metal bar fixed between the second molars as a reference structure was digitized using the CEREC Primescan AC scanner (N = 225 scans). Nine scanning strategies were selected (n = 25 scans...

Background: The determination of the maxillary occlusal plane presents a significant clinical challenge in the treatment of edentulous patients as well as it is critical for complex full-mouth reconstructions in dentate patients, including those with implant-supported rehabilitations. While the use of a Fox plane plate is standard in edentulous ca...

Objectives Clinical data on all‐ceramic screw‐retained implant crowns (SICs) luted on titanium base abutments (TBAs) over more than 3 years are sparse. This study aimed to evaluate the clinical performance and potential risk factors for these restorations. Materials and Methods Analysis took place based on the medical patient‐records of three dent...

Purpose: This in vitro study investigated the influence of material selection, crown morphology, and vertical crown height on the biomechanical behavior of monolithic hybrid abutment crowns (HACs). Methods: Ninety implants were embedded in accordance with ISO standard 14801; ninety HACs were mounted (N=90). Monolithic crowns with varying group-spec...

Polymer-basierte Füllungsmaterialien gelten heutzutage als Standard im Bereich der direkten plastischen Versorgung von Kavitäten. Insbesondere die Weiterentwicklung der Polymere hin zu CAD/CAM-basierten Hochleistungspolymeren in den letzten Jahren ermöglichte die Nutzung Polymer-basierter Materialien auch zur Herstellung indirekter Restaurationen....

Die Innovationsrate und die Marktdurchdringung im Bereich digitaler Dentaltechnologien haben sich in den letzten Jahren enorm beschleunigt. Während sich bei den subtraktiven Fertigungsverfahren seit längerem ein beachtliches Entwicklungs- und Produktivitätsniveau bei breitem Indikationsspektrum etabliert hat, haben additive Verfahren (3D-Druck) bes...

Mithilfe der additiven Multimaterialfertigung können aus verschiedenen Legierungen bestehende Teile in digitalen Prozessketten gefertigt werden. In dem Beitrag wird die Anwendbarkeit der Technologie für die Dentalbranche anhand zweier Applikationen gezeigt und bewertet.

Objective: Several extrusion techniques have been described to restore teeth with insufficient coronal tooth structure and to avoid their extraction. Still, there is little evidence for a treatment concept combining surgical extrusion using an atraumatic axial extraction system. Materials and methods: A total of nine patients, each with an iso-...

Pronounced defects of the dental hard tissue can be caused by different etiological factors. Most frequently, they are associated with changes in the vertical dimension of occlusion, which also may influence the condylar positions. Leading to irreversible loss of tooth structure, these defects can have dramatic functional and esthetic consequences...

Ob für Situationsaufnahmen, zur Patientenkommunikation, für digitale Planungen oder zur Chairside-Versorgung: Intraoralscanner (IOS) sind inzwischen in vielen Praxen fester Bestandteil des Praxisalltags. Mit der stetigen Weiterentwicklung der IOS steigt auch das Angebot an intraoral-optischen Abformsystemen. Die Vielzahl der am Markt verfügbaren IO...

The thickness of a material has a significant impact on its fracture load. The aim of the study was to find and describe a mathematical relationship between the material thickness and the fracture load for dental all-ceramics. In total, 180 specimens were prepared from a leucite silicate ceramic (ESS), a lithium disilicate ceramic (EMX), and a 3Y-T...

ZUSAMMENFASSUNG Parodontologen sowie Prothetiker werden zukünftig aufgrund der demografischen Entwicklung vermehrt mit komplexen Planungen von verschiedenen Lückengebisssituationen im parodontal kompromittierten Gebiss konfrontiert sein. Das synoptische Behandlungskonzept bildet die Grundlage für eine langfristig erfolgreiche kaufunktionelle und äs...

(1) Background: New intraoral (IOS) and laboratory scanners appear in the market and their trueness and precision have not been compared. (2) Methods: Seven IOS and two laboratory scanners were used to scan a mandibular edentulous model with four parallel internal hexagon implant analogues and PEEK scan bodies. Digital models in Standard Tessellati...

The computer-aided manufacture of esthetically pleasing monolithic dental restorations presents with specific challenges. One vital parameter to consider is the translucency of the materials. Previous studies have proven a correlation between translucency and material thickness for various all-ceramic materials. The aim of the present study was to...

Background Digital teaching and learning tools, such as computer/mobile apps, are becoming an important factor in modern university education. The objective of our study was to introduce, analyze, and assess an organization and dual assessment app for clinical courses in dental medicine. Methods This was a survey-based study of dental students fro...

Purpose: This in vitro study aimed to investigate the long-term performance, stability, and fracture mode of monolithic hybrid abutment crowns, and the effect of different materials on the implant-abutment interface (IAI). Methods: Eighty monolithic hybrid abutment crowns luted on titanium bases were manufactured from 3Y-TZP zirconia (ZY3), “Gradie...

Die subtraktive Fertigung digital konstruierter Totalprothesen mittels „Frästechnik“ ist unter den computergestützten Herstellungstechniken derzeit diejenige der Wahl. Aber auch geeignete additive Fertigungsverfahren könnten in dieser Indikation sinnvoll zum Einsatz kommen. Ziel der vorliegenden Studie war, die Passgenauigkeit von Totalprothesenbas...

Purpose: To analyze the clinical performance of two-wing retained resin-bonded fixed dental prostheses (RBFDPs) after 5 years of clinical use with respect to technical and biologic complications as well as survival and success rates. Materials and methods: RBFDPs were either made of 3Y-TZP zirconia layered by hand (LAVA frame veneered with LAVA...

The aim of this in vitro study is to investigate the bonding properties of a 3D-printable permanent composite material in comparison to milled composite materials. The tested materials are 3D-printed BEGO VarseoSmile Crown plus (VA1_ab, VA1_nt, VA2_ab, VA2_nt), Vita Enamic (EN1, EN2), and 3M Lava Ultimate (UL1, UL2) (N = 64; n = 8). For this purpos...

Bislang waren die zur Zahnrestauration verfügbaren 3D-Druck-Materialien lediglich für den temporären Einsatz zugelassen. Mit der seit Kurzem erfolgten Zulassung des ersten Polymers zur additiven Fertigung von definitivem Einzelzahnersatz wird die Frage nach den Vorteilen und Limitationen des definitiven Zahnersatzes aus dem 3D-Drucker aktueller den...

Purpose: To evaluate the shear bond strength (SBS) of different digital veneering techniques for zirconia and to critically discuss its suitability for application in single-implant prosthetics. Materials and methods: A total of 112 square-shaped zirconia specimens were provided with four different veneering materials (n = 28 per group): a glass...

Initial therapy with occlusal splints is a key stage of complex prosthetic rehabilitation due to changes in the vertical dimension of occlusion. Good patient compliance is crucial to the success of treatment. In addition to the desire for minimally invasive treatments, patients have increasingly demanding expectations regarding esthetic and functio...

Der Verlust der Vertikaldimension ist oftmals mit einem hohen Behandlungsaufwand verbunden, da in der Regel alle Zähne zumindest eines Kiefers therapiert werden müssen. Neben der Frage, welche prothetisch-restaurative Versorgung die ideale ist, spielt die Funktionsdiagnostik eine wesentliche Rolle für den Erfolg einer komplexen Bisslagenveränderung...

Objectives To compare the accuracy (trueness and precision) of direct digitization of four different dental gap situation with two IOS (intraoral scanner). Materials and methods Four partially edentulous polyurethane mandible models were used: (1) A (46, 45, 44 missing), (2) B (45, 44, 34, 35 missing), (3) C (42, 41, 31, 32 missing), and (4) D (fu...

Aim: To determine the effect of intraoral conditions on the accuracy of digital full-arch scans. Materials and methods: A reference bar was used for the in vivo and in vitro parts of the present study. For the in vitro part (PAT-vitro), the bar was fixed to connect the maxillary second molars on the patient's resin model. The same reference bar...

Für den Langzeiterfolg von vollkeramischen Restaurationen sind die Indikationsstellung, die Werkstoffauswahl, die Beachtung der Funktion sowie die Berücksichtigung von materialspezifischen Eigenschaften essenziell. Das im Juni 2021 veröffentlichte Update der S3-Leitlinie „Vollkeramische Kronen und Brücken“ (AWMF-Reg.-Nr. 083-012) zeigt einen Rahmen...

Aim: Milling-based, subtractive fabrication of digital complete dentures represents the computer-engineered manufacturing method of choice, but efficient additive manufacturing technologies might prove beneficial for the indication as well. The aim of this study is to evaluate the accuracy of surface adaptation of complete denture bases fabricated...

Objective This paper presents a novel digital workflow that expedites and facilitates the manufacturing of high-end full-ceramic restorations based on “Print and Press”-Technology combined with 3D-printed colored 3D-models. Clinical considerations Despite ongoing innovations and developments in the digital workflow, the precision, and the final es...

Data on the long-term behavior of computer-aided designed/computer-aided manufactured (CAD-CAM) resin-based composites are sparse. To achieve higher predictability on the mechanical behavior of these materials, the aim of the study was to establish a mathematical relationship between the material thickness of resin-based materials and their fractur...

An increasing number of accuracy studies on 3D digitizing systems, especially intraoral scanning devices, are being published in scientific and educational journals. The methods, measurement values, and statistical parameters of these studies vary. Certain inconsistencies exist, which lead to difficulty in terms of interpretation and sometimes even...

PURPOSE: The aim of this study was to evaluate the efficiency of occlusal and interproximal adjustments of single implant crowns (SIC), comparing a digital cast-free approach (CF) and a protocol using 3D printed casts (PC). MATERIALS AND METHODS: A titanium implant was inserted at position of lower right first molar in a typodont. The implant posit...

PURPOSE: Purpose of this in vitro study was to determine the accuracy of different intraoral scans versus laboratory scans of impressions and casts for the digitization of an edentulous maxilla. MATERIALS AND METHODS: A PEEK model of an edentulous maxilla, featuring four hemispheres on the alveolar ridges in region 13, 17, 23 and 27, was industrial...

Objectives To report assessments of four systematic reviews (SRs) on (i) clinical outcomes of all-ceramic implant-supported crowns (iSCs), (ii) production time, effectiveness, and costs of computer-assisted manufacturing (CAM), (iii) computer-assisted implant planning and surgery (CAIPS) time and costs, and (iv) patient-reported outcome measures (P...

Polycarbonates are polymers of bisphenol A (BPA), a well-known endocrine disruptor. This study evaluated the release of BPA from polycarbonate crowns that were (1) milled from Temp Premium Flexible (ZPF, Zirkonzahn, Italy) or Tizian Blank Polycarbonate (TBP, Schütz Dental, Germany), or (2) 3D-printed (Makrolon 2805, Covestro, Germany). Commercial p...

Dentale Keramiken gelten wegen ihres ästhetischen Potenzials und ihrer hohen Biokompatibilität als exzellentes Material, um den Zahn restaurativ zu versorgen. Zudem erweitert sich das Materialangebot kontinuierlich um Hybridkeramiken und Hochleistungspolymere. Vorteile sind einfache Herstellung im digitalen Workflow oder ausbleibendes Chipping, doc...

Aim: To study the time and costs involved with computer-assisted versus non-computer-assisted implant planning and placement. Material and methods: Based on the PICO question, "In patients receiving dental implants, is computer-assisted implant planning and surgery (CAIPS) compared to non-computer-assisted implant planning and surgery (non-CAIPS...

ENGLISH: The number of single-tooth implants has been steadily increasing in recent years, so that their superstructures have to prove themselves for a wider range of patients than ever in terms of longevity, esthetics, and function. The combination of CAD/CAM technology and new restorative materials especially enables innovative and efficient ther...

Statement of problem: Making impressions of 2-piece implants is typically associated with the repeated disassembly and reassembly of superstructures and related to soft-tissue trauma. Intraoral scanning of 1-piece zirconia implants is problematic because scan bodies are not readily available. Whether using virtual hybrid casts generated by merging...

Abstract The aim of this study was to quantify and to compare the wear rates of premolar (PM) and molar (M) restorations of lithium disilicate ceramic (LS2) and an experimental CAD/CAM polymer (COMP) in cases of complex rehabilitations with changes in vertical dimension of occlusion (VDO). Twelve patients with severe tooth wear underwent prosthetic...

Purpose: The aim of this study was to evaluate the stability of single crowns and 3-unit bridges in relation to the implant-abutment complex with and without tube in tube connection. Methods: 60 specimens with a total of 90 implants (diameter 3.8 mm) were fabricated and distributed into 4 groups: CST (Crown with short tube), CLT (crown with long tu...

Background: The esthetic outcome of a dental restoration largely depends on the translucency of the materials used, especially for monolithic restorations. Research has been published reporting a correlation between translucency and material thickness. However, no mathematical formula has been described yet. The aim of the present study was to det...

Popular media now often present 3D printing as a widely employed technology for the production of dental prostheses. This article aims to show, based on factual information, to what extent 3D printing can be used in dental laboratories and dental practices at present. It attempts to present a rational evaluation of todays´ applications of 3D printi...

Purpose: Bone augmentation and implant placement often lead to a coronal shift of the soft tissue. Therefore replacement of the mucogingival border during second-stage surgery is required. Different techniques have been described in the literature. Material and methods: In this case report a new technique for second-stage surgery from a combinat...

Objectives To evaluate the advantages of student satisfaction with and functionality of three digital teaching concepts during the SARS-CoV-2 pandemic compared to a conventional lecture setup. Methods This cross-sectional study was a survey-based e-learning research among dental students in the clinical study phase of a department of prosthetic de...

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 zirco...

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...

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 wer...

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...

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 pati...

Objectives To analyse the residual monomer (MMA) elution of polymethyl methacrylate (PMMA) in distilled water after diverse fabrication methods and aging procedures.Materials and methodsPMMA specimens (N = 192, PalaXpress; Kulzer, Hanau, Germany) were manufactured (pouring, n = 96/injection, n = 96) and polymerized in water (55°C) without pressure...

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 fro...

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 (C...

Die Entwicklungsgeschwindigkeit im Bereich der Digitalen Zahn-heilkunde hat ein enormes Tempo angenommen. Für Praktiker wird es zunehmend schwieriger, auf dem aktuellen Stand zu bleiben und das Potenzial neuer Technologien und Konzepte rea-listisch einzuschätzen. Im nachfolgenden Beitrag sollen einige der nach Ansicht der Autoren interessantesten d...

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 t...

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 ar...

Die Entwicklungsgeschwindigkeit im Bereich der digitalen dentalen Fertigungstechnologien hat ein enormes Tempo angenommen. Während im Bereich der subtraktiven Verfahren bereits ein hohes Produktivitätsniveau mit optimalen Passungen erreicht ist, gewinnen additive Verfahren (3-D-Druck) zunehmend an Bedeutung. Aber auch Kombinationen aus verschiedene...

Das Sachverständigenpapier „Status Präsens 2020: die additiven CAD/CAM-gestützten Fertigungstechnologien im zahntechnischen Labor“ gibt eine objektive Darstellung der derzeitigen additiven digitalen Fertigungsmöglichkeiten im zahntechnischen Labor. Ziel ist es, der Öffentlichkeit realistisch das Anwendungsspektrum der additiven CAD/CAM-Fertigung be...

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...

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...

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 rece...

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 maxi...

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 mat...

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....

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...

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 FPD...

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 (CS3...

Die Einführung der Adhäsivtechnik in Kombination mit zahnfarbenen Restaurationsmaterialien zählt zu den größten Errungenschaften der restaurativen Zahnheilkunde. Dazu haben adhäsiv befestigte Veneers auf der Basis verschiedener silikatkeramischer Materialien ganz wesentlich beigetragen. Sie haben sich zu einer ernsthaften Behandlungsalternative zu...

The digital workflow presented here allows for fabrication and placement of a definitive custom abutment at the time of tooth extraction and guided immediate implant placement, thus preserving soft tissue anatomy. Since abutment design was based on the shape of the original tooth, it represented a de facto emergence‐analog that provided ideal soft...

Objectives: Evaluation of survival and complication rate of monolithic occlusal onlays made of lithium disilicate ceramic used in patients with severe tooth wear up to 11years of clinical service. Methods: In a prospective non-randomized clinical study 7 patients (4 male, 3 female; median age: 44.3±6.56years old) were restored full mouth with a...

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: Impla...

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 desig...