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« Juli 2018 »

Univ.-Prof. Dr.

Matthias Frentzen

Zentrum für Zahn-, Mund- und Kieferheilkunde der
Rheinischen Friedrich-Wilhelms-Universität

Raum: 131/132, 1.Etage

Tel.: 0228/287-22470

Mail: frentzen(at)

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Information [english]

“Swap Drills for Light Energy”- Interdisciplinary collaborative research project funded by the BmBF at the University of Bonn The project: MiLaDi (Minimally Invasive Laser Ablation and Diagnosis of Oral Hard Tissue) is funded by the Federal Ministry of Education and Research with a total current budget of 6.8 million €. The partners, besides the University of Bonn, are Sirona Dental Systems GmbH and a medium-sized laser manufacturer. The goal is to develop new laser therapy systems on the basis of ultrashort pulse laser technology with large ranges of applications.

The guiding principle of prevention-oriented dentistry is to offer (laser) light-based diagnosis and therapy treatment with outstanding capabilities. An example for this, is the early detection of hidden carious lesions, which are clinically and radiographically hardly detectable, using light-induced fluorescence. Through a combination of photosensitizers and light, bacteria contaminated gingival pockets can be disinfected. Laser light is even capable of replacing the scalpel, allowing incisions resulting in reduced blood loss, and benign alterations of the mucous membrane. These are just a few of the many new possibilities and developments made by clinical diagnosis and treatment of mouth and dental disease through laser-based technology.

For 20 years the corporation “Laser in dentistry” at the University of Bonn’s Dental and Oral Health Centre has accompanied the research, directed under Univ.-Prof. Dr. M. Frentzen, and participated in a number of national and international development projects. This includes the collaborative project MiLaDi for the research of the so called ultrashort pulse laser technology. The project involves a BmBF funded Research Association of the workgroup “Lasers in dentistry” in Bonn, working in cooperation with two industrial companies: Sirona Dental Systems GmbH and Lumera Laser GmbH; a manufacturer with many years of experience with ultrashort pulse lasers in science and industrial material machining. The main goal of the MiLaDi project, is the oral biological and medical research and testing of a laser diagnostic and treatment device, based on a picosecond laser source, in dentistry.

During the last few years, ultrashort pulse lasers have been introduced to fundamental research in dentistry. This technology offers the prospect, to efficiently treat oral hard and soft tissues with minimal damage. The highly precise removal of biological tissues should also be affiliated with reduced pain.

The first experience gained with this short pulsed laser technology was in the 90s with nanosecond pulsed-excimer laser, which radiated in the ultraviolet range of the spectrum. Recent ultrashort pulse laser technology is based on laser devices with wavelengths of around 1µm (e.g. Nd:YAG lasers), and with pulse durations from picoseconds to femtoseconds. The tissue ablation with this type of laser is not based upon the physical principle of absorption, but on non-linear optical effects in combination with the plasma generation.

In the near future ultrashort pulse laser therapy should enable users to:

  • remove minimally invasive hard tooth substance (enamel, dentin, as well as  bone caries)  and mineralized concretions (such as tartar or concrements) with little or no pain, and allow an objective analysis of the removed material
  • carefully handle surrounding tissue when treating bone; for instance, to perform orthopaedic surgery in implantsurgery
  • perform surgical procedures on healthy and sick oral soft tissue, and carry out the analysis of the removed materials
  • perform biofilm management of the oral plaque associated diseases in the areas of cariology, endodontology, and periodontology


As a part of ongoing research, the fundamental examination is performed to examine the effect of the ultrashort pulse radiation on biological tissue and restoration materials. The detection procedure can then be tested, based on fluorescence and plasma spectroscopy FIG 1 [Fluorescence effects as a useful diagnostic tool during ablation of dentin by means of ultrashort pulse laser technology].

To test the clinical relevance in the treatment of dental hard tissue, the processing speed of enamel and dentin must be determined.  The ablation volume of dentin, without air or spray is approximately 10 mm3/min. The efficiency seems to significantly improve due to optimization, and in particular due to the scan parameters. Carious dentin can be ablated significantly faster than healthy dentin.

The cavities do not show any histological indications for thermal damage and a smooth and extremely sharp edge contour, it seems as though no smear layer is built FIG 2 [Photomicrograph of laser cavity. Smooth cavity walls show no dissection-related side effects (x16)]. Consequently, it is possible to specifically prepare cavities with laser. In order to ensure a sufficient width of the therapy spectrum with ultrashort pulse laser technology, restoration materials were also tested with this technology to show to what extent they could be handled. Clinically relevant ablation rates, by the usual tested materials, indicate a possibility of an effective laser protective treatment on restoration materials FIG 3 [Photomicrograph of laser cavity in composite. Right is the 3D display of the same cavity. The defined edges of the cavity are particularly distinguishable here].

The basis for the surgical application of ultrashort pulse lasers is the efficient and careful ablation of oral soft and bone tissues without secure adverse effects. As histological studies show, bone can be handled without spray and air cooling with no detectable side effects FIG 4 [Atraumatic high-precision ablation of bone tissue {overview of an undecalcified section through the cavity (x100)}]. The clinical efficiency is, according to available results, comparable to traditional methods.


The collaborative project is currently focusing on the systematic examination of relevant laser parameters, as well as the development of a suitable radiative transfer system, including adequate detection systems.  The results achieved so far are very promising and open up the possibility for patient-oriented advancement.


Contact Address:

AG Laser in der Zahnheilkunde

Zentrum für Zahn-, Mund- und Kieferheilkunde der

Rheinischen Friedrich-Wilhelms- Universität Bonn

Welschnonnenstr. 17

53111 Bonn

Tel.: 0228-287-22470

Fax: 0228-287-22146


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