Correlating micromorphology of the pulpal odontoblast seam using confocal laser scanning microscopy and dark field microscopy.
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Dental Pulp↗
Biomedical subjects
H Duschner
Publications and source records attributed to H Duschner.
Efficacy of NaOCl/H2O2 irrigation and GaAlAs laser in decontamination of root canals in vitro.
BACKGROUND AND OBJECTIVES: To investigate the bactericidal effect of an 809 nm semiconductor laser alone, and in combination with NaOCl/H(2)O(2) irrigation in root canals in vitro. STUDY DESIGN/MATERIALS AND METHODS: A total of 72 human single-rooted teeth extracted for periodontal reasons were included. The crowns were removed, the roots shortened to a length of 12 mm, and the canals enlarged up to an apical size of #50 file. The specimens were autoclaved and incubated with a suspension of Streptococcus sanguinis (ATCC 10556). Laser irradiation was performed on a PC-controlled XY translation stage. A 200 micron optic fiber was used. Twelve specimens were irradiated at a power output of 1.5, 3.0, and 4.5 W in the cw-mode. The total irradiation time was 60 seconds per canal. Twelve specimens were rinsed with NaOCl and H(2)O(2) only, 12 were rinsed and laser treated, and 12 served as untreated controls. After laser treatment, the specimens were sonicated and the bacterial growth was examined by counting colony forming units on blood agar plates. Temperature changes at the outer root surface during irradiation were registered by means of thermocouples. Treated and control specimens were investigated by means of scanning electron microscopy. RESULTS: Mean bacterial reductions of 0.35 log steps at a power output of 1.5 W, 1.44 at 3.0 W, and 2.84 at 4.5 W were calculated. Bacterial reduction by the NaOCl/H(2)O(2) solution alone was 1.48 and comparable to that achieved by irradiation at 3.0 W. With a log kill 2.85, the combination of rinsing and laser irradiation at 3.0 W resulted in a further significant bacterial reduction as compared to rinsing alone (P = 0.004). Irradiation did not result in excessive heat generation at the root surface. Carbonization of the root canal wall was observed in single teeth at 3.0 and 4.5 W and no controlled sealing of the dentinal tubules could be achieved in the root canal. CONCLUSIONS: The application of the diode laser might be an adjunct to conventional endodontic treatment when used in combination with a NaOCl/H(2)O(2) solution.
Colony Count, Microbial↗
Interactions between cells and titanium surfaces.
The interaction between cells and implant materials is determined by the surface structure and/or surface composition of the material. In the past years, titanium and titanium alloys have proved their superiority over other implant materials in many clinical applications. This predominant behaviour is caused by a dense passive oxide layer which forms within milliseconds in oxidizing media. Titanium dioxide layers of 100 nm thickness were produced on the surface of cp-titanium grade 2, and on an experimental alloy of high vanadium content (Ti1.5Al25V) as a harmful control. The layers were produced by thermal and anodic oxidation and by coating by means of the sol-gel process. The resulting oxide layers were characterized with respect of their structure and chemical composition. In cell tests (proliferation, MTT, morphology, actin staining), the reaction of the cells was examined. It was shown that the sol-gel-produced titanium oxide layer is able to shield the cells from toxic alloying elements, with the result that the cell reaction is influenced only by the thin titanium oxide surface layer and not by the composition of the bulk material.
Actins↗
Effect of diode laser irradiation on root surfaces in vitro.
OBJECTIVE: The objective of this study was to evaluate possible morphological alterations of root surfaces after GaAlAs-diode laser (809 nm) irradiation under standardized in vitro conditions. MATERIALS AND METHODS: Root specimens obtained from extracted periodontally diseased teeth were scaled and root planed with curettes followed by air-powder abrasive treatment prior to lasing. The variable parameters were power output (0.5-2.5 W) and exposure time (10-30 sec per specimen). Additionally, the effect of a saline solution and a human blood film on the root surface was investigated. The root segments were analyzed by means of a reflected light microscope. Photographs before and after irradiation were taken and evaluated. The scale of carbonization was quantified using a grid laid over the photographs. Specimens with distinct morphological changes were analyzed with a scanning electron microscope. RESULTS: Lasing dry specimens and specimens moistened with saline resulted in no detectable alterations, irrespective of irradiation time and power output applied. Depending on different settings, irradiation caused severe damages to the root surface when segments were covered by a thin blood film. Irradiation at a power output of 1 Watt and below had barely any negative effect on the root surface, whereas lasing at 1.5, 2.0, and 2.5 Watt resulted in partial or total carbonizations of the root samples. The angle of irradiation had a significant effect on the scale of the root surface damage (Mann-Whitney U test,p < 0.05). CONCLUSION: The diode laser may cause damage to periodontal hard tissues if irradiation parameters are not adequate.
Humans↗
Outline and arrangement of enamel rods in human deciduous and permanent enamel. 3D-reconstructions obtained from CLSM and SEM images based on serial ground sections.
Human enamel rods were made visible continuously from the dentino-enamel junction (DEJ) up to the enamel surface. From 12 teeth (1st and 2nd dentition) enamel blocks from the cervical third were prepared with perpendicular planes, embedded in resin, and ground down in steps of 15 microm parallel to the enamel surface. Enamel rods were made visible by acid etching (35% H3PO4, 45 s), sputtered and examined in the scanning electron microscope (SEM). Prior to this, the enamel blocks were viewed under the CLSM and optical sections at distances of 2 microm were obtained, starting in the same plane as the grinding surface. The outlines of the rods were digitized and reconstructed three dimensionally. For the first time, the path of single and grouped enamel rods on their way through the entire enamel layer was depicted. 3D images obtained from confocal laser scanning microscopy (CLSM) data were similar to those gained from SEM images. Single rods did not maintain their same outline throughout their path; arcade outlines predominated close to the DEJ, while keyhole outlines prevailed at the enamel surface. Within a group of rods, neighborhood relations changed, and neighbor rods influenced their outlines mutually, including the variable extent of the tail. The interdependence between the plasticity of the rods and the ameloblasts' forms should be topics of further research.
Dental Enamel↗
Nanoleakage at the composite-dentin interface: a review.
The term "nanoleakage" was introduced to describe a specific type of leakage within the dentin margins of restorations. Nanoleakage appears as a consequence of the acid etching procedure allowing the penetration of oral and pulpal liquids such as acids into porosities within or adjacent to the hybrid layer. Nanoleakage is independent from microleakage. The amount of penetration depends on the type of bonding agent and on different parameters of the application technique (e.g. etching time, dentin moisture). Nanoleakage is much less extensive than microleakage and has probably no short-term clinical relevance. The long-term stability of the adhesive bond between dentin and restorative material, however, might be adversely affected. Nevertheless, based on the knowledge to date, acid etching prior to dentin bonding should be performed.
Acid Etching, Dental↗
Effect of intrapulpal pressure simulation in vitro on shear bond strengths and hybrid layer formation.
PURPOSE: To test the hypothesis that simulation of an intrapulpal pressure during the application of dentin bonding systems influences hybrid layer formation in vitro. MATERIALS AND METHODS: 180 teeth and three different bonding agents were used for shear bond strength measurements and for confocal laser scanning microscopy studies on the dentin-composite interface. The bonding agents (30 teeth each material) were applied without (90 teeth, Group A) and with intrapulpal pressure simulation of 34 cm H20 with water (90 teeth, Group B). 45 specimens from each group were sheared in a testing machine, and 45 teeth from each group were used for CLSM studies after labeling the primer components of the bonding agents with a fluorescent dye. RESULTS: After simulation of pulpal pressure the bond strengths decreased significantly in all groups (Syntac [without/with]: 16.0 +/- 4.5/8.0 +/- 3.7, P= 0.001; Gluma: 13.3 +/- 4.6/8.4 +/- 4.4, P= 0.008; Prime & Bond NT: 14.8 +/- 5.8/8.7 +/- 5.7, P= 0.007; n = 15 each; U-tests). There were no significant differences between the hybrid layer thickness without/with simulation of pulpal pressure (Syntac: 3.6 +/- 0.6/4.1 + 1.2, P= 0.35; Gluma: 3.5 +/- 0.6/3.7 + 0.9, P= 0.49; Prime & Bond NT: 3.5 +/- 0.9/3.8 + 0.8, P= 0.44; n = 15 each; U-tests). In the case of simulation of an intrapulpal pressure, CLSM examination revealed a distinctly shallower penetration of the adhesives into dentin compared to the samples treated without intrapulpal pressure.
Acid Etching, Dental↗
Using ultrasound transmission velocity to analyse the mechanical properties of teeth after in vitro, in situ, and in vivo irradiation.
Ultrasound transmission velocity (UTV) in isotropic material as a measure for the modulus of elasticity was correlated to mechanical properties. Changes in micromechanical properties of radiated teeth and influence of the oral cavity were to be evaluated nondestructively. UTV was measured in extracted teeth after 36 Gy and 62 Gy of in situ (enorally, with no contact to the oral cavity) and in vitro irradiation. Relative to controls, teeth subjected to 62 Gy in vivo showed higher UTV values for dentine and enamel. Sound teeth irradiated with 60 Gy in situ also showed higher UTV values for enamel, whereas dentine values were not significantly different from those of control. The mechanical properties of teeth irradiated in vitro were affected only after high experimental doses of up to 500 Gy. The difference between in vivo and in vitro mechanical properties may be due to radioxerostomia-induced damages as well as the status of dentine vitality. This supports the concept of direct radiation-induced damage in synergy with radioxerostomia-induced caries.
Cranial Irradiation↗
Terminal end of the human odontoblast processes.
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Dental Enamel↗
[Determining the size of the specific surface of bone substitutes with gas adsorption].
The surface area and the microporosity of bone regeneration materials influence their chemical and biological properties. Therefore, the size of the specific surface area and the distribution of the pore diameters (pores < 1 micron) of bone regeneration materials were analyzed within this study. The analyzed hydroxyapatites were of synthetic, bovine, and phytotroph origin. The tricalcium phosphates and the bioglasses included only synthetic materials. The gas adsorption of each specimen was analyzed using a volumetric N2/Kr system (ASAP 2010, Micromeritics). Additionally, for materials with a specific surface area (> 2 m2/g) the pore size distribution was evaluated by the BJH-method. Two of the materials evaluated astonishingly large dimensions of the specific surface area (BioOss 79.7 m2/g, Algipore new 14.6 m2/g). A medium surface area was found for Algipore old (4.9 m2/g) and Interpore200 (2.64 m2/g). All other included materials showed only small sizes of the specific surface area (Ceros80 1.8 m2/g, Ceros82 1.31 m2/g, Cerasorb 1.2 m2/g, Biobase 0.7 m2/g, Endobone 0.7 m2/g, Perioglas 0.6 m2/g, Allotropat50 0.23 m2/g, Biogran 0.2 m2/g). The materials with large and medium sizes of the specific surface area evaluated the following pore diameters: BioOss 2-50 nm, Algipore new 2-100 nm, Algipore old 5-50 nm, Interpore200 2-100 nm. Pore sizes less than 2 nm were not found in relevant numbers. The materials BioOss, old and new Algipore, and Interpore200 contain a large interconnecting mesopore system (diameter < 1 micron). For the materials Biobase, Endobone, Perioglas, Allotropat 50, and Biogran this cannot be assumed. The materials Ceros80, Ceros82, and Cerasorb evaluated a specific surface area between those and might include only a small part of these interconnecting pores. An influence of the interconnecting porosity and the different sizes of the specific surface areas on the biological behavior of the bone regeneration materials can be suggested.
Adsorption↗
Changes in the extracellular matrix of the vein wall--the cause of primary varicosis?
BACKGROUND: Conflicting theories on the development of primary varicosis have led to the molecular biological investigation of the vein wall or, more accurately, of the extracellular matrix. It was the aim of this study to quantify matrix expression and to compare pathological changes in the vein wall with valve-orientated staging of varicosis, in order to determine indicators of the primary cause of varicosis. MATERIALS AND METHODS: Three hundred seventy-two tissue specimens of greater saphenous veins were obtained from 17 patients with varicosities and categorised according to Hach stage and procurement site. The specimens were compared with 36 specimens collected from six patients without varicosities, incubated with fluorescence-stained antibodies for collagen 4, laminin, fibronectin and tenascin prior to being assessed with confocal laser scan microscopy. In addition, 22 vein specimens (16 varicose, 6 normal veins) serving as negative controls were investigated. RESULTS: Image analysis and statistical evaluation showed that compared with normal veins, varicose veins are associated with a significant increase in matrix protein expression for collagen 4, laminin and tenascin. A trend towards an increase in matrix expression was further observed for fibronectin. There was, however, no difference between varicose veins and clinically healthy vein segments inferior to a varicose segment. CONCLUSION: If the findings of the present investigation can be confirmed by other studies, alterations in the vein wall may be regarded as the primary cause of varicosis and valvular insufficiency as the result of these changes.
Extracellular Matrix↗
The nanoleakage phenomenon: influence of different dentin bonding agents, thermocycling and etching time.
"Nanoleakage" takes place within the hybrid layer zone of the dentin-composite interface in spaces not occupied by polymerized resin. The purpose of this study was to quantify the amount of nanoleakage in specimens treated with one of six different bonding agents. For one agent, different etching times were used, and for two agents results after thermocycling were obtained. Standardized class V cavities were prepared in 165 extracted human molars with cervical margins located in dentin. After placement of the composite using bonding agents, the teeth were stored in a 1% rhodamin-B-isothiocyanate solution for 24 h at 20 degrees C, embedded in methacrylate, and sectioned parallel to the long axis of the tooth. A confocal laser scanning microscope was used to visualize a layer 10 microm below the prepared surface of the section. The lengths of the penetrated pathways were measured, representing the amount of nanoleakage. In all materials tested, penetration pathways appeared within the hybrid layer in absence of gap formation. Penetration lengths of the tested materials were in a range from 69 +/- 24 microm to 469 +/- 333 microm. Thermocycling had no statistically significant influence, and etching for 15 s resulted in statistically significantly shorter penetration compared to longer etching.
Acid Etching, Dental↗
Confocal laser scanning microscopy: A nondestructive subsurface histotomography of healthy human bone.
Microscopy of bony tissue usually requires special treatment for decalcification and processing of thin sections. Confocal laser scanning microscopy (CLSM) allows the nondestructive histotomography of organic hard tissue. The aim of this study was to visualize healthy human bone structures and to correlate identical areas in CLSM and conventional light microscopy. Each sample of healthy human lower jaw (n = 20) was divided into three parts: (1) fresh, untreated bony blocks studied by CLSM; (2) MMA-embedded thin sections (without decalcification), HE stained and studied by CLSM and conventional light microscopy (correlation of identical areas); (3) decalcificated, HE stained, histological sections studied by conventional light microscopy. In untreated bony blocks, microstructures such as osteocytes and lamellae were identified by CLSM. These structures could be correlated with conventional light microscopy. In CLSM, subcellular structures cannot yet be interpreted, whereas cytoplastic processes of osteocytes were seen with high contrast. With CLSM, nondestructive histology of cortical bone can be obtained. The risk of artifacts due to pretreatment is minimized, and subsurface visualization does not affect the interpretation.
Histological Techniques↗
[Micromorphological findings in jaw bone after radiotherapy. Confocal laser scanning microscopy and fluorescence darkfield microscopy studies].
Early radiation effects on human bone may lead to osteoradionecrosis (ORN). Direct bone cellular lesions [28] as well as fibrous degeneration of blood vessels [21] are considered to be pathologically relevant. Only few data on initial subclinical radiation effects are available. Patients were grouped according to the dose of radiation and clinical findings. Group 1: sound human bone of lower jaw, mostly collected during orthodontic surgery (n = 10 patients); group 2: specimens of lower jaw from patients with ORN (n = 12 patients); group 3: specimens of lower jaw from patients with head and neck cancer who were preoperatively treated with 36 Gy radiation; group 4: specimens of lower jaw from patients with head and neck cancer (n = 9) who were treated with 60-70 Gy radiation. Specimens were studied by confocal laser scanning microscopy (CLSM), by conventional light microscopy (DL) and by fluorescence darkfield microscopy (DFM) after bisbenzimide staining (H 33258) of the viable cellular nuclei. For the correlating study of identical areas in CLSM and DL the specimens were prepared according to the sawing and grinding technique [8]. All the radiated bony specimens, regardless of the dose of radiation, showed areas of extensive or total loss of vitality of the osteocytes. This finding was also evident after 36 Gy and a short interval between radiation and sample collection (group 3). Additionally, in CLSM micromorphologic lesions of the lamellate structure were seen. With these results we can confirm the loss of vitality of the osteocytes as an initial radiation effect as described earlier [10, 23, 28]. In addition to these findings, alteration of the lamellate microstructure was found in the early phase after radiation. The functional and mechanical significance of these findings should be the subject of further studies.
Bone and Bones↗
Cariostatic effect of a light-cured, resin-reinforced glass-ionomer for bonding orthodontic brackets in vivo. A combined study using microradiography and confocal laser scanning microscopy.
The aim of this study was to evaluate in vivo the cariostatic potential of the resin-reinforced glass-ionomer (Vitremer core build-up restorative; 3M Dental Product Division) when used as a bonding agent for orthodontic brackets. The mineral distribution and topography of the enamel surface adjacent to the bracket base was determined by quantitative microradiography (TMR) and confocal laser scanning microscopy (CLSM). The study was designed in split-mouth technique using 9 pairs of premolars to be extracted for orthodontic reasons. One tooth of each pair was bonded with the resin-reinforced glass-ionomer, and the control contralateral premolar with the non-fluoridated composite (Concise, 3M Dental Products Division). After 4 weeks all teeth were extracted and stored until analysis. The lesion depths and mineral loss values in enamel adjacent to brackets bonded with Vitremer were significantly lower than in teeth bonded with the composite, indicating that the resin-reinforced glass-ionomers significantly reduced caries lesion development in vivo. CLSM images show a severe cariogenic challenge around orthodontic brackets and support TMR measurements.
Bicuspid↗
Histotomography of the odontoblast processes at the dentine-enamel junction of permanent healthy human teeth in the confocal laser scanning microscope.
The translucency of teeth allows the non-destructive subsurface visualisation of their microstructure by confocal laser scanning microscopy (CLSM) at a level of about 150 microns below the surface. The dentine-enamel junction (DEJ) is accessible only directly adjacent to the cervix of the tooth. Therefore teeth have to be sectioned for studying marginal areas of the dental hard tissue. The potential of the technique for (pseudo) three-dimensional visualisation allows the study of an array of individual confocal images, the interpretation of which is similar to that of macroscopic tomographs (CT-scan, MRI). Additionally, the extended focus mode yields the overlay of individual confocal images in the form of a two-dimensional projection. This mode of operation proved to be particularly suited for the visualisation of odontoblast processes in their whole extension. The three-dimensional junction between enamel and dentine, the branches of the odontoblast processes and their interactions with the DEJ is demonstrable by CLSM without staining or other procedures of sample preparation. The direct microscopic comparison between samples, either fresh or kept in a humid chamber, and Technovit-embedded sample blocks gives evidence that the risk of artefacts by sample storage or by the embedding procedure is minimal. The tomographs limited to subsurface areas of the tissue also exclude mechanical surface artefacts due to grinding or cutting.
Dental Enamel↗
[Histotomography studies of direct radiogenic dental enamel changes].
OBJECTIVE: The volume of literature on radiation-induced caries is still inconsistent as regards the state of the art. Our histotomographic studies have shown direct radiogenic effects on the dentoenamel junction (atrophy of the odontoblast processes). Whether there are direct effects of radiation on dental enamel is not yet known. MATERIAL AND METHOD: Sound teeth (group 1, n = 10) were compared either with enamel specimens after high dose in vitro radiation (500-2500 Gy; group 2; n = 10) and after experimental enoral in situ irradiation (60 Gy; group 3; n = 20), or with teeth from patients after cancer radiotherapy (36 Gy; group 4; n = 20) and with teeth which had obviously decayed due to cancer radiotherapy (60 Gy; group 5; n = 20). Vestibular enamel surfaces of the teeth were exposed to identical in vitro demineralizations (lactic acid gel; pH = 5.0). Each of the samples was prospectively studied histologically by confocal laser scanning microscopy (CLSM) after 90, 180 and 270 min of acid interaction. Data were interpreted micromorphometrically (width of the demineralized area) and micromorphologically. RESULTS: The width of the demineralized area varies between the two in vivo irradiated groups of specimens (group 4: P < 0.01; group 5: P < 0.001) and the high dose in vitro irradiated teeth (P < 0.01) and is significantly different from the sound controls. The histological image of the demineralization in subsurface areas in the teeth of radiotherapy patients is characterized by a total loss of the prismatic structure (homogeneously, amorphous substance). CONCLUSIONS: Direct radiogenic effects at the dentoenamel junction have been described earlier. The additional information offered by this study is that there are significant micromorphometric differences in the demineralizing behaviour of irradiated enamel. Obviously, enamel is less resistant to acid attack after irradiation.
Cobalt Radioisotopes↗
[Confocal laser scanning microscopy (CLSM) for validation of non-destructive histotomography of healthy bone tissue].
OBJECTIVES: Fixation (formalin), decalcification (sections) or mechanical treatment (grinding) all bear the risk of artifacts occurring during hard-tissue histology. Because studies on the etiology of pathological changes mostly focus on subclinical lesions, artifacts can simulate early changes or even be superimposed on existing changes. The objective of this study was to determine how artifacts can be reduced. MATERIAL AND METHODS: In confocal laser scanning microscopy (CLSM) a focused laser beam scans the surface of the specimens and penetrates into the tissue. The intensity of the remitted light is recorded. The confocal effect is due to an extremely small aperture (pin-hole), excluding light from out-of-focus planes of the sample. By stepwise movement of the object table, a tomographic series of tomographic images is obtained. Sound cortical bone samples of the lower jaw (n = 20) were studied by light microscopy and by CLSM, visualizing identical areas of a ground sectioned sample after H&E staining. Additionally, embedded and fresh blocks of tissue of the same bone sample were studied histotomographically in the CLSM. RESULTS: (1) Light microscopic micromorphology of cortical bone can be visualized adequately in the CLSM; (2) many structures that can be visualized by light microscopy only after special staining (e.g., osteozyte processes) can be visualized by the CLSM using sample blocks without pretreatment. CONCLUSION: (1) Nondestructive subsurface histotomography by CLSM totally excludes mechanical artifacts; (2) physicochemical artifacts can be handled more easily because fresh samples can be studied; (3) pseudo-three-dimensional imaging allows histological interpretation of the tissue that is equivalent to macroscopic tomographic techniques (CT, MRT).
Artifacts↗