Biomedical subjects

T Liesenhoff

Publications and source records attributed to T Liesenhoff.

6 recordsLinked to original sources

PubMed1998

Bactericidal action of 308 nm excimer-laser radiation: an in vitro investigation.

The aim of the present study was to investigate the influence of 308 nm excimer-laser radiation on bacterial growth. Six different bacterial strains (Staphylococcus aureus, Escherichia coli, Streptococcus faecalis, Lactococcis lactis, Salmonella typhimurium, and Deinococcus radiodurans) were exposed in vitro to various doses and energy densities of laser radiation. To exclude bacterial killing by supraphysiological heating, the temperature change in the samples during irradiation was measured. Extended antimicrobial effects of XeCl excimer-laser radiation depending on the time of radiation, the energy density of the laser beam, and the irradiated bacterial strain were observed. Reduction of bacterial growth is independent of temperature and not linked to any ablative tissue removal. In almost all cases, a 99.9% reduction of bacteria was reached by total radiation times < 100 ms. The proven antimicrobial effects of 308 nm excimer-laser radiation may be of significant clinical importance in endodontics and periodontology in the future.

Analysis of Variance↗

PubMed1994

Treatment of temporomandibular joint structures by 308-nm excimer laser--an in vitro investigation.

Arthroscopy of the temporomandibular joint (TMJ) has become a clinically important and increasingly accepted method for diagnosis and treatment of TMJ alteration. This minimally invasive method is clearly limited by the anatomic dimensions of the TMJ. The 308-nm excimer laser has already found clinical applications in angioplasty, ophthalmology, and dentistry. This study aimed to find out whether it is possible to ablate TMJ-related structures under arthroscopic conditions. It also aimed to determine the energy threshold for ablation and the maximum rate of ablation. By histologic investigation of the irradiated tissues, the amount of tissue alteration was determined. TMJ structures of freshly slaughtered pigs served as tissue samples. The 308-nm excimer laser light was guided through optical fibers. The tissue was irradiated under continuous flow of saline solution. The energy threshold for ablation of TMJ structures was found at about 1 J/cm2. The maximum rate of ablation was found at 3-5 micron/pulse, depending on the type of tissue. The amount of tissue alteration varied between 1 and 150 microns. The types of tissue alteration were vacuolization and hyalinization. The results of the investigations described indicate that the 308-nm excimer laser is an ideal tool for TMJ arthroscopic surgery. Unlike other laser systems, it offers a unique combination of minimal tissue alteration, precise tissue ablation, guidability through optical fibers, and good transmission through water. This makes possible endoscopic removal of free bodies, adhesions, exostoses, and appositions in a minimally invasive surgical procedure.

Animals↗

PubMed1990

[Basic considerations on the use of the Excimer laser in dentistry].

SEM studies showed that irradiation in the energy density range of 4-6 J/cm2 resulted in the removal of hard tooth structure without causing thermal alterations of the tissues. In this process (photoablation) the natural structures of the tissues are "exposed". The surface structure thus produced in dentin depends on whether the dentin tubules are hit transversally or longitudinally and varies accordingly. The surface structure of enamel, as well, is determined by the alignment of the prisms. When the laser beam was optimally adjusted (energy densities of 4-6 J/cm2 and peripheral fading), no structural changes could be demonstrated in the depth of the tissue.

Dental Cavity Preparation↗

PubMed1989

[Removal of hard tooth substance with Excimer lasers].

The usefulness of an Excimer laser (wavelength 308 nm) to remove enamel and dentin was assessed by examining the necessary energy flow density, micromorphological changes, and irradiated surfaces. Our results demonstrated that it is possible to remove dentin and enamel with the Excimer laser in controlled fashion. The temperature in the pulp cavity rose as a function of the distance to the site of irradiation (corresp. to distance between temperature measuring probe and irradiated tooth surface) and the duration of exposure and amounted to 3.5 degrees C-18.3 degrees C. Differences in the micromorphology of the surface structures were observed as a function of the material (enamel or dentin) and the duration of irradiation.

Dental Cavity Preparation↗

PubMed1989

[Root canal preparation using Excimer laser beams].

An in vitro investigation of root canal preparation on extracted human teeth by 308 nm Excimer Laser radiation was performed. It could be demonstrated that a secure and effective root canal preparation is possible by Excimer Laser radiation. SEM investigations on axially splitted roots showed root canal walls free of smear layer or any other soiling. The dentin-tubuli where open and free of clogging. There was no case of via falsa or overinstrumentation.

Evaluation Studies as Topic↗

PubMed1989

[Usefulness of Excimer lasers in dentistry].

In vitro investigation on the influence of 308 nm excimerlaserradiation on extracted human teeth. Depending on the distance of the area of radiation to the pulp the temperaturerise ranged from 3.5 degrees C (6 mm) to 18.2 degrees C (less than 0.5 mm). REM investigations of radiated surfaces indicate a good retention of filling materials. TEM investigations of radiated dental hard tissues demonstrated that there is no structural change of the ultrastructure below the radiated surface.

Dental Restoration, Permanent↗