Biomedical subjects

Peter Schüpbach

Publications and source records attributed to Peter Schüpbach.

3 recordsLinked to original sources

PubMed2005

The human bone-oxidized titanium implant interface: A light microscopic, scanning electron microscopic, back-scatter scanning electron microscopic, and energy-dispersive x-ray study of clinically retrieved dental implants.

BACKGROUND: Surface modification of titanium implants by anodic oxidation may lead to enhanced bone integration. For instance, in vivo studies have demonstrated formation of more bone contacts in less time than for turned control implants. In addition, oxidized implants have shown a higher resistance to torque forces, indicating a strong interlock between bone and the oxide layer. However, the structure of the oxidized titanium-bone interface in high resolution is not known. PURPOSE: The aim of the study was to analyze the human bone-oxidized titanium interface at a high-resolution level. Of particular interest was the relationship between bone tissue and the pores of the surface oxide. MATERIALS AND METHODS: Twelve clinically retrieved implants with an oxidized surface (TiUnite, Nobel Biocare AB, Göteborg, Sweden) were used. Seven were regular dental implants and five were experimental mini-implants and had been subjected to immediate, early, or no loading. They were retrieved after 5 to 9 months of healing and were processed and analyzed using light microscopy, scanning electron microscopy (SEM) in normal and back-scatter (BS-SEM) modes, and energy-dispersive x-ray (EDX) analysis techniques. RESULTS: Bone formation was observed to occur from adjacent bone structures toward the implant surface, and it was evident that bone formation had occurred at the implant surface. SEM, BS-SEM, and EDX revealed that mineralized bone had grown into the pores of the surface oxide layer, including pores with small diameters (< 2 microm). CONCLUSIONS: The clinically retrieved oxidized implants showed evidence of bone growth into the pores of the surface oxide layer. The findings indicate the establishment of a strong interlock between the bone and the oxidized titanium implant, which is suggested to be beneficial for clinical performance.

Coated Materials, Biocompatible↗

PubMed2005

Periimplant soft tissue barrier at experimental one-piece mini-implants with different surface topography in humans: A light-microscopic overview and histometric analysis.

BACKGROUND: Following connection to the oral cavity, osseointegrated dental implants and surrounding tissues are exposed to microbiologic and biomechanical challenges. The establishment of a firm functional periimplant soft tissue barrier (PSTB) is considered to be important to protect the implant's interface from invasion of bacteria. The current knowledge on the histologic architecture of the PSTB is mainly based on animal experiments. PURPOSE: The aim of this study was to histologically characterize the PSTB formed in humans around experimental one-piece mini-implants with different surface topography. MATERIALS AND METHODS: Five patients received a total of 12 experimental titanium, one-piece mini-implants with an oxidized (n = 4), an acid-etched (n = 4), or a machined (n = 4) surface distal to therapeutic implants. Following transmucosal healing of 8 weeks and at abutment connection of the regular implants, the mini-implants were harvested with a layer of surrounding hard and soft tissue. The specimens were fixed and processed for histologic sectioning according to standard procedures. The most central bucco-oral section cut in the long axis was used for morphologic analyses of the PSTB. The vertical soft tissue morphology was quantified using histometric measurements. RESULTS: The overall height of the soft tissue, that is, the biologic width, was around 4 to 4.5 mm and consisted of an epithelial and a supracrestal connective tissue barrier. The junctional epithelium established the attachment to the implant surface, whereas the collagen fibers and fibroblasts of the connective tissue seal were oriented parallel to the implant. The epithelial attachment was shorter at the oxidized and acid-etched surfaces compared with the machined surfaces. Accordingly, the oxidized and acid-etched mini-implants exhibited a longer zone of connective tissue seal. CONCLUSION: The periimplant soft tissue formed at the experimental one-piece mini-implants in humans was of a character similar to that described in animal studies. The oxidized and acid-etched implants revealed less epithelial downgrowth and longer connective tissue seal than machined implants.

Acid Etching, Dental↗

PubMed2005

Fluorescence microscopy for the evaluation of the margins of Class V restorations in vitro.

PURPOSE: First, to elucidate the cause of the appearance of "white lines" in Class V restorations as seen under the light microscope and their enhancement when using a fluorescent microscope (FM); second, to compare the results of the FM quantitative marginal analysis to those of the SEM quantitative marginal analysis. MATERIALS AND METHODS: Thirty-two standardized Class V fillings, with half of the preparation in dentin and half in enamel, were placed in 16 human caries-free premolars on the buccal and lingual surface using 4 adhesive systems (Clearfil SE, Syntac, 2 experimental self-etching adhesives) and the composite Tetric Ceram. All teeth were connected to a device containing horse serum to simulate dentinal fluid and subjected to thermomechanical loading (1,200,000 cycles at 49 N, 3000 cycles at 5 degrees C/55 degrees C). The restoration margins of 24 fillings were directly evaluated with FM--after the fabrication of replicas--and with SEM. Eight fillings were used to elucidate the cause of the fluorescent signal, by examining them with FM and different filters under dry and moist conditions, and also with dark field microscopy and CLSM. Further, two Class V fillings with the same composite but without the fluorescent substances were made and evaluated. Selected specimens were cut in the bucco-oral direction to analyze the restorative interface on section replicas with SEM. To detect differences between FM and SEM, the Wilcoxon test was performed (p < 0.05). To evaluate the degree of agreement between the two evaluation methods, a linear regression analysis was performed and the Spearman correlation coeffcient was calculated. RESULTS: The evaluation of Class V restorative margins by SEM, dark field microscopy, and CLSM revealed that the phenomenon seems to be an optical effect caused by the debonding of the composite from the underlying substrate creating another refractive environment when air penetrates into the gap. The effect depends on the geometry of the cavity design, the absence of moisture, and the use of a fluorescent composite material. The light source that produced the best visible results covered both ultraviolet and the blue part of white light (350 to 460 nm), producing light green lines and green areas. Those green or white areas as seen with the light microscope were related to gaps in the interface between tooth substance and composite. With the exception of one of the experimental self-etching adhesives, the mean percentage of continuous margin of the 4 groups showed no statistically signifcant dfference for the two test methods. Linear regression analysis revealed a good correlation between the two test methods for dentin margins and a moderate correlation for enamel margins. CONCLUSION: Fluorescence microscopy seems to be a useful tool for evaluating dentinal and enamel margins of Class V restorations in vitro.

Adhesives↗