Biomedical subjects

Hans-Ulrich Luder

Publications and source records attributed to Hans-Ulrich Luder.

5 recordsLinked to original sources

PubMed2006

Biocompatibility of Beta-tricalcium phosphate root replicas in porcine tooth extraction sockets - a correlative histological, ultrastructural, and x-ray microanalytical pilot study.

This investigation studies porcine tissue response in tooth extraction sockets treated with root replicas made out of Beta-tricalcium phosphate (Beta-TCP; Beta-Ca(3)(PO(4))(2)) granules, molded and held together by thermal fusion of a thin film of polyglycolic-polylactic acid copolymer. Six left mandibular third incisors (n (1)/4 6) of experimental pigs are treated with the root replicas and four contralateral incisors are used as nontreated controls (n (1)/4 4). Two animals each were killed at 20, 40, and 60 weeks of observation periods. The mandibular jaw segments were prepared in toto for light microscopy by resin embedding and serial ground sectioning. Additionally, one Beta-TCP-treated socket at 60 weeks was thoroughly investigated by correlative light, electron microscopic and electron probe X-ray microanalysis to assess the bio-absorbability and host removal of the replica material from the implant site. The extraction wounds of the animals healed satisfactorily with very little histologically observable differences in the healing pattern of the test and control sites. The Beta-TCP was completely removed from extracellular sites, but at 60 weeks, remnants of it were found in the cytoplasm of multinucleated giant cells. The root replicas made out of Beta-TCP were biocompatible and bioabsorbable. Osseous healing occurred both in the test and control sockets, but the healing process was delayed due to the presence of Beta-TCP particles.

Animals↗

PubMed2003

Pulpal response to Er:YAG laser drilling of dentine in healthy human third molars.

BACKGROUND AND OBJECTIVES: Maintenance of pulpal health is a critical prerequisite for successful application of light amplification by stimulated emission of radiations (lasers) in the hard tissue management of vital teeth. The purpose of this study was to investigate the short- and long-term pulpal effects to cavity-preparations in healthy human teeth using erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser. MATERIALS AND METHODS: A total of seven healthy third molars that were to be removed due to space-problem were used. Following the laser excavation, the cavities in dentine were closed temporarily and the teeth were extracted after 7 days (n = 5) and 3 months (n = 2) post-operation. The specimens were fixed, decalcified, subdivided, and processed for light and transmission electron microscopy. RESULTS: In the short-term group, four of the five laser-drilled teeth did not reveal any pathological changes in the pulp-dentine complex. One tooth showed mild disruption of odontoblasts (OB) and vascular dilatation subjacent to the deepest point of the cavity-preparation with a remaining dentine thickness (RDT) of less than 80 microm. The two teeth under long-term observation revealed distinct apposition of tertiary dentine (TD), lined predominantly with cuboidal cells on its pulpal aspect. CONCLUSIONS: These results would allow a conclusion to be drawn that the Er:YAG laser under investigation is a pulp preserving hard-tissue drilling tool when used with the specific energy settings and emitting radiation at a wavelength of 2.94 microm.

Dental Pulp↗

PubMed2003

Performance of visual inspection, electrical conductance and laser fluorescence in detecting occlusal caries in vitro.

The aim of this study was to compare visual inspection (VI) and electrical conductance (EC) and laser fluorescence (LF) measurements in detecting occlusal caries. VI was based on fissure discoloration and performed with the naked eye. EC was measured with the ECM device (Lode Diagnostic, Groningen, The Netherlands), and LF was assessed with the DIAGNOdent apparatus (KaVo, Biberach, Germany). In extracted human premolars and molars, clinically sound sites (D0-/D1-lesions), enamel caries (D2-lesions), and dentinal caries (D3-/D4-lesions) were identified using recommended cut-off values. Thereafter, the teeth were cut longitudinally and analyzed by scanning electron microscopy for verification of caries depth. Reproducibility of VI was good, that of EC and LF excellent. In identifying caries at both the enamel and dentin level, the sensitivities of VI and LF were significantly (p < 0.05) higher than that of EC, while EC was significantly (p < 0.05) more specific. The positive predictive values, however, did not exceed 43%. Improved diagnoses at the dentinal level were obtained, when EC and LF were used as an adjunct to VI and when cut-off values were raised. Thus, visual inspection relying exclusively on fissure discoloration seems to allow only proper identification of sound occlusal surfaces. In cases of discolored fissures, the appliance-based methods help to avoid false positive identification of dentinal caries. However, attainable reliabilities of diagnoses do not seem to exceed about 50% to 60%.

Adolescent↗

PubMed2002

Factors affecting degeneration in human temporomandibular joints as assessed histologically.

The influence of sex, age, tooth loss, and articular disc position on temporomandibular joint (TMJ) degeneration was evaluated in specimens collected at autopsy from 15 women and 38 men ranging in age from 15 to 92 yr. The position of the articular discs was classified as normal or abnormal, tooth loss was both counted and categorized. Degenerative changes of the articular tissues were assessed histologically and quantified, taking into account both the severity of structural alterations and their extension along the articular surface. This was recorded separately in the condyle, disc, and temporal component, three latero-medial joint regions, and putative load-bearing and non-load-bearing surfaces. Analysis of covariance with repeated measures served for testing contributing factors. It showed that the effects of sex and the number of missing teeth were insignificant, whereas age up to about 55-60 yr and reduction of dental arch length proved to be the most important factors. Load-bearing seemed to play a significant role mainly at younger ages, and the effect of disc position was significant, when internal derangement was combined with reduction of dental arch length. Thus, rising severity of TMJ degenerative changes appears to be associated primarily with increasing age. In addition, it may also depend on mechanical factors, in particular loss of molar support and, to a minor degree, abnormal disc position.

Adolescent↗

PubMed2002

Ciliated epithelium-lined radicular cysts.

OBJECTIVE: This report describes 3 cases of ciliated epithelium-lined radicular cysts among 256 apical periodontitis lesions and also illustrates the occurrence of an Actinomyces-infected periapical cyst. STUDY DESIGN: Serial and step serial sections of 256 plastic-embedded root apices with attached apical periodontitis lesions that were prepared for a previous investigation were reviewed for the presence of ciliated epithelium-lined radicular cysts. The lesions that were found to have such epithelial lining were examined in a transmission electron microscope to elaborate the fine structure of the ciliated cells. RESULTS: A total of 3 ciliated columnar epithelium-lined cysts was found among the 256 apical periodontitis lesions examined. Two of the lesions also contained stratified squamous epithelium. All 3 lesions affected maxillary premolars. One of the lesions was a true cyst, and the other 2 were periapical pocket cysts. The lumen of 1 of the latter revealed the presence of typical "ray-fungus" actinomycotic colonies. CONCLUSION: Although the stratified squamous component of the epithelia that lined the radicular cysts reported here may be derived from the cell rests of Malassez, the ciliated epithelial cells may be of sinus origin. Microbial agents from diseased root canals can advance into radicular cysts, particularly in pocket cysts, with the possible threat of such infection in upper posterior teeth spreading into the maxillary sinus.

Actinomyces↗