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Dental Prosthetics and Restorative Dentistry

Research Focus
General Facts
Research
Selected Publications
Selected Funding, Collaboration
Devices & Services

Keywords: Dental prophylaxis; periodontics; orphan diseases; Ehlers-Danlos syndromes; Amelogenesis imperfecta; dental ceramics; composite materials; adhesive systems; dentine bonding; bond strength
Research (ÖSTAT Classification) : 3542, 3206

Research Focus

• Adhesive systems for composite resins and dental ceramics (René Steiner)
• Rare diseases with dental and/or periodontal manifestations (Ines Kapferer-Seebacher, Dagmar Schnabl, Ulrike Lepperdinger)
• Mechanical oral hygiene devices (Ines Kapferer-Seebacher, Vera Wiesmüller)

General Facts

The University Hospital for Dental Prosthetics and Restorative Dentistry is part of the Department of Dental and Oral Medicine and Cranio-Maxillofacial and Oral Surgery. One main task of the department is the comprehensive and evidence-based training of dental undergraduate students in prosthetic and restorative dentistry. About 100 dental students receive daily supervision in practical training and patient treatment. Since the 70s, the University Hospital has been known for its outstanding work in dental prophylaxis training for dental students. Oral hygiene instructions for self-performed mechanical plaque control are a key element of successful dental prophylaxis. One of our research topics is therefore the investigation of new mechanical oral hygiene devices. The research focus of the department is traditionally on issues concerning dental materials science, with a special focus on clinical and in vitro analysis of dental ceramics and dentine adhesive systems. In recent years, joint collaborations with the Institute of Human Genetics and the University Hospital for Dermatology, Venereology and Allergology have improved comprehensive patient service for individuals with rare diseases and oral phenotypes. As a result, several top publications have been produced on the molecular basis and clinical features of hereditary diseases with dental and/or periodontal manifestations, with a special focus on oral manifestations of Ehlers-Danlos syndromes.

Research

Dental Ceramics, Composite Filling Materials and Adhesive Systems
René Steiner

The choice of adhesive system and composite resin has an impact on the clinical success of composite restoration and must be made carefully. Because of this, we started a series of in vitro investigations, measuring the push-out bond strength of various composites on dentine, by means of single and multi-stage adhesive systems. We were able to detect that fluid composites display higher push-out bond strengths than universal and bulk-fill composites – a surprising finding, since fluid composites comprise fewer and smaller fillers than universal and bulk-fill composites. Further, we demonstrated that multi-stage adhesives have greater bond strengths than single-stage adhesives; this is an important statement, which contradicts the common belief of dental practitioners in the industry suggestion of using single-stage adhesives for reasons of time saving. In a second step, we analysed the fracture types of the composite at the dentine-composite interface (Fig. 1). Fluid composites showed predominantly mixed, whereas universal and bulk-fill composites showed adhesive failure types. In conclusion, we can state that fluid composites should become increasingly significant as restoration materials, especially in cavity lining, owing to their excellent wetting properties and high bond strength on dentine.

^{Fig. 1: Fracture analysis of a mixed failure type. Interface between composite resin (C) and dentine (D) after the push-out test. The lines mark the adhesive fracture (adh) and the cohesive fracture (coh) (incident light microscopic image; ×50 magnification).}

Hereditary Diseases with Oral Phenotypes
Ines Kapferer-Seebacher, Dagmar Schnabl, Ulrike Lepperdinger

The long-standing collaboration with the Division of Human Genetics and the Department of Dermatology has resulted in several research projects on clinical phenotypes and the molecular basis of rare diseases with oral phenotypes. In the course of this collaboration, we have built up an outstanding international database on patient data of Ehlers-Danlos syndromes (EDS). In a joint project with NHS EDS services in London and Sheffield (UK) and the Department of Child Neurology, VU University Medical Center in Amsterdam (NL), we have identified specific gingival phenotypes as pathognomonic features and white brain matter alterations as consistent manifestations of periodontal EDS. In collaboration with the University of Grenoble Alpes (France), we have further elucidated the functional effects of C1S/C1R mutations in pEDS on molecular and enzymatic level.

For amelogenesis imperfecta, we have reported on heterozygous SLC24A4 variants causing mild hypomaturation defects, providing evidence that the function of SLC24A4 in calcium transport has a crucial role in the maturation stage of amelogenesis (Fig. 2).

The prosthetic rehabilitation and long-term dental care of individuals suffering from X-linked hypohidrotic ectodermal dysplasia is another long-standing clinical and research topic of our clinic.

^{Fig. 2: Histological analysis of primary teeth extracted from individuals with homozygous mutations in SLC24A4 has shown that amelogenesis imperfecta is of the hypomaturation type. The teeth were block-stained with fuchsin and, after embedding in methyl methacrylate and perpendicular sectioning, the specimens were polished and contrast-stained with acetic light green (original magnification 12 – 60x). The image shows an irregular enamel surface, structureless enamel and many cracks. Chipping of enamel has occurred on the mesiobuccal cusp and the abfraction is filled with debris. The fuchsin-stained area (red) on the distobuccal cusp is indicative of a caries lesion. The structure of the dentine is normal.}

Oral Hygiene Devices
Ines Kapferer-Seebacher, Dagmar Schnabl, Vera Wiesmüller

In an ongoing series of randomised controlled clinical studies, we are evaluating the plaque removal efficiency of mechanical tooth cleaning devices to improve and facilitate the oral hygiene efforts of our patients. For example, we are evaluating the cleaning efficiency of various “ten-second” auto-cleaning devices that have been developed for individuals with poor dexterity or compliance (Fig. 3). In another top publication, we have demonstrated the cleaning efficacy superiority of waist‐shaped rather than cylindrical interdental brushes. In a current project together with the University Hospital for Orthodontics, we are designing a cleaning sequence for individuals with fixed orthodontic appliances.

^{Fig. 3: The Amabrush® auto-cleaning device is a horseshoe-shaped, biplane mouthpiece mounted with four rows of silicone bristles on the oral and vestibular side of the upper and lower jaw part. The mouthpiece must be attached to a rechargeable handpiece, which contains a toothpaste pod from which a defined amount of toothpaste sufficient for one brushing session is released at the touch of a button. Over 20,000 bristle oscillations per minute are designed to clean the teeth within 10 seconds.}  

Selected Publications

• Steiner R, Edelhoff D, Stawarczyk B, Dumfahrt H, Lente I.: Effect of Dentin Bonding Agents, Various Resin Composites and Curing Modes on Bond Strength to Human Dentin. Materials (Basel). 2019 Oct 17;12(20):3395.
• Kapferer-Seebacher I, Oakley-Hannibal E, Lepperdinger U, Johnson D, Ghali N, Brady AF, Sobey G, Zschocke J, van Dijk F. Prospective clinical investigations of children with periodontal Ehlers-Danlos syndrome identify generalized lack of attached gingiva as a pathognomonic feature. Genet Med 2020 Oct 2. doi: 10.1038/s41436-020-00985-y. Online ahead of print.
• Lepperdinger U, Maurer E, Witsch-Baumgartner M, Stigler R, Zschocke J, Lussi A, Kapferer-Seebacher I: Expanding the phenotype of hypomaturation Amelogenesis imperfecta due to a novel SLC24A4 variant. (2020) Clin Oral Invest 24(10):3519-3525.
• Kapferer-Seebacher I, Waisfisz Q, Boesch S, Bronk M, van Tintelen P, Gizewski ER, Groebner R, Zschocke J, van der Knaap MS.: Periodontal Ehlers-Danlos syndrome is associated with leukoencephalopathy. 2019 Mar;20(1):1-8. doi: 10.1007/s10048-018-0560-x. Online ahead of print.
• Schnabl D, Wiesmüller V, Hönlinger V, Wimmer S, Bruckmoser E, Kapferer-Seebacher I.: Cleansing Efficacy of an Auto-Cleaning Electronic Toothbrushing Device: A Randomized-Controlled Crossover Pilot Study. Clin Oral Investig. 2020 Jun 6. doi: 10.1007/s00784-020-03359-5. Online ahead of print.

Selection of Funding

• 2020: Grant for health and social care applicable to the Ehlers-Danlos syndromes and hypermobility spectrum disorders (€ 96.000) - Ines Kapferer-Seebacher
• 2019: Austrian Research Promotion (FFG) novelity cheque (€ 12.500) - Ines Kapferer-Seebacher

Collaborations

•  Daniel Edelhoff and Bogna Stawarczyk, Department of Prosthodontics, Dental School, Ludwig-Maximilians University Munich, Germany
• Fleur Van Dijk, Neeti Ghali, and Angela F. Brady, National diagnostic EDS service, London, United Kingdom
• Glenda Sobey and Diana Johnson, National diagnostic EDS service, Sheffield, United Kingdom
• Adrian Lussi, Department of Operative Dentistry and Periodontology, Faculty of Dentistry, University Medical Centre, Freiburg, Germany
• Marjo S. van der Knaap, Department of Child Neurology and Department of Functional Genomics, Center for Neurogenomics and Cognitive Research, VU University Medical Center, Amsterdam, The Netherlands
• Nicole Thielens and Christine Gaboriaud, University of Grenoble Alpes, CEA, CNRS, IBS, Grenoble, France
• Christine Gaboriaud and Nicole Thielens, Groupe IRPAS (Immune response to pathogens and altered self), Institut de Biologie Structurale, Grenoble, France

Devices & Services

• Sawing and grinding machines for dental histology
• Universal testing machine
• Chewing simulator
• Profilometer
• Thermocycler

Univ.-Prof.ⁱⁿ Dr.ⁱⁿ med.univ. Dr.ⁱⁿ med.dent. Ingrid Grunert
Director
Contact:
Anichstraße 35, MZA
6020 Innsbruck
Austria
Email: ingrid.grunert@i-med.ac.at
Phone: +43 512 504 27159
Fax: +43 512 504 27157
www.zmk-innsbruck.at