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Biomedical subjects

W Niedermeier

Publications and source records attributed to W Niedermeier.

At least 19 recordsLinked to original sources
PubMed1998

Reactions of peri-implant tissues to continuous loading of osseointegrated implants.

Functional and morphologic reactions of peri-implant bone surrounding screw implants (Bonefit) were studied in three dogs by loading the implants with continuous forces of 2 (about 204 gm) and 5 N (about 510 gm). Eight implants were inserted to an endosseous length of 12 mm and placed about 10 mm apart in the region of the lower premolars. The fixtures healed in a closed environment for 12 weeks, after which they were uncovered and loaded with abutments and orthodontic devices to produce horizontal distraction with a force of 2 N (about 204 gm) for 12 weeks. Subsequently they were loaded with 5 N (about 510 gm) for another 24 weeks. The distance between and the mobility of the implants were determined before and after each phase of experimental loading. Fixtures of the same type that were osseointegrated and not exposed, or osseointegrated and loaded by mastication, were used as a control. Animals were euthanized and specimens sectioned. The result was that continuously loaded implants showed no significant displacement for any force level. The mobility of the fixtures increased slightly by about 1 Periotest-value (PTV) at the end of the experiment. No significant peri-implant pocket could be seen in implants loaded by continuous or masticatory forces. Histologic and morphometric evaluation indicated compaction of bone as a result of loading. Osseointegrated implants have potential as a firm osseous anchorage for orthodontic treatment and can resist continuous horizontal forces of at least 5 N (about 510 gm) during a period of several months.

Absorptiometry, Photon↗
PubMed1998

Radiation-induced hyposalivation and its treatment with oral pilocarpine.

OBJECTIVE: The aim of this study was to determine the effects of radiation on the secretion of saliva from mucous salivary glands in comparison with serous salivary glands. STUDY DESIGN: The minor salivary glands of the palate were used as an example of mucous glands, while the parotid glands were used as an example of a serous secretion organ. Serial flow rate measurements of the parotid and palatal glands were taken over a period of approximately 9 months in 13 patients who suffered from malignancies of the head and neck region. Twelve patients consented to take part in a second study in which salivary flow was stimulated by oral pilocarpine before and at the conclusion of radiotherapy and 7 months later. Complaints and symptoms were recorded at each time of measurement. RESULTS: After radiotherapy, the secretory performance of the parotid glands dropped off rapidly and irreversibly. Salivary secretion from the palatal glands was not totally diminished as a result of radiation. Clinical complaints and histologic findings indicate a serious alteration of the tissues irradiated; however, residual secretion from the remaining parenchyma of the mucous glands still remains. Pilocarpine produced a clinically significant increase of salivary flow from the palatal glands before and 7 months after radiation. Secretory performance of the parotid glands could not be sufficiently increased by stimulation with pilocarpine after radiotherapy. Clinical side effects and risks for the treatment of symptomatic postradiation xerostomia with pilocarpine were minimal. CONCLUSIONS: These findings emphasize the greater resistance and recoverability of the mucous secreting minor palatal glands in comparison with the serous secreting parotid glands. They also indicate the significant postradiation ability of the mucous secreting glands to be stimulated by pilocarpine.

Carcinoma, Squamous Cell↗
PubMed1997

DC electrical field-induced c-fos expression and growth stimulation in multicellular prostate cancer spheroids.

The effects of electrical direct current (DC) field pulses on c-fos expression, growth kinetics and vitality patterns of multicellular tumour spheroids (MCSs) were studied. Monitoring the membrane potential of MCSs by di-8-ANNEPS staining and confocal microscopy during DC electrical field treatment revealed a hyperpolarization at the anode-facing side and a depolarization at the cathode-facing side. When a single 500 V m(-1) electrical field pulse with a duration of 60 s was applied to MCSs (150-350 microm in diameter) an enhancement of the growth kinetics within a period of 6 days post pulse was observed. Whereas the volume doubling time amounted to 4-5 days in control samples, it was reduced to 1-2 days in electropulsed MCSs. At day 6 post pulse the diameter of the necrotic core was significantly smaller than the control. The critical diameter for the first appearance of central necrosis amounted to 350 +/- 50 microm in the control and 450 +/- 50 microm in the electropulsed MCSs. Coincidentally, the proliferating rim was increased to 107 +/- 11 microm in electropulsed MCSs as compared with 60 +/- 6 microm in the control. The growth stimulation may be mediated by the proto-oncogene c-fos as its expression increased by a factor of 2.5 within 2 h post pulse. c-fos expression declined towards control values within 8 h post pulse.

Buffers↗
PubMed1993

Parameters of tooth mobility in cases of normal function and functional disorders of the masticatory system.

Tooth mobility was measured mechano-electronically with the aid of quasi-static and dynamic methods in 309 patients comprising 2650 teeth being periodontally healthy. Besides, clinical and roentgenographic findings were ascertained to relate functional features to each periodontium. In general the result was that teeth loaded excessively show increased mobility parameters compared to those loaded normally. However, the mobility of teeth loaded poorly or deficiently was even greater compared to teeth stressed excessively. Moreover, follow-up studies showed that tooth mobility decreases after removal of functional disorders of the masticatory system or an immobilisation of splinted teeth. An experimental trauma of the periodontal ligament also brings on an increased tooth mobility which decreases to the original values some days after the trial.

Adolescent↗
PubMed1993

The paradox between resistance to hypoxia and liability to hypoxic damage in hyperglycemic peripheral nerves. Evidence for glycolysis involvement.

Isolated ventral and dorsal rat spinal roots incubated in normal (2.5 mM) or high glucose (25 mM) concentrations or in high concentrations of other hexoses were exposed transiently to hypoxia (30 min) in a solution of low buffering power. Compound nerve action potentials, extracellular direct current potentials, and interstitial pH were continuously recorded before, during, and after hypoxia. Ventral roots incubated in 25 mM D-glucose showed resistance to hypoxia. Dorsal roots, on the other hand, revealed electrophysiological damage by hyperglycemic hypoxia as indicated by a lack of posthypoxic recovery. In both types of spinal roots, interstitial acidification was most pronounced during hyperglycemic hypoxia. The changes in the sensitivity to hypoxia induced by high concentrations of D-glucose were imitated by high concentrations of D-mannose. In contrast, D-galactose, L-glucose, D-fructose, and L-fucose did not have such effects. Resistance to hypoxia, hypoxia-generated interstitial acidification, and hypoxia-induced electrophysiological damage were absent after pharmacological inhibition of nerve glycolysis with iodoacetate. These observations indicate 1) that enhanced anaerobic glycolysis produces resistance to hypoxia in hyperglycemic peripheral nerves and 2) that acidification may impair the function of peripheral axons when anaerobic glycolysis proceeds in a tissue with reduced buffering power.

Action Potentials↗
PubMed1991

[Factors involved in endosseous implant function].

Periodontometric and Periotest mobility parameters of 87 endosseous implants were studied during a period of up to 6 years. Moreover, the condition of the surrounding bone and mucosa was assessed by means of the Periodontal Index (PI). Mobility of endosseous implants was lowest during the first year of insertion and highest at the end of the study. Among all those variables that had a favorable effect on implant function, the length of the implants was in the first line. What is called the osseointegration of dental implants is no longer evident after just a short period of masticatory loading by a denture. Mobility parameters of implants then increase to those of periodontally healthy natural teeth. Improved dental hygiene and cleansing of the periimplant area reduce the incidence of pathological findings and improve the prognosis of dental implants.

Adult↗
PubMed1990

[Morphological and functional characteristics of the palatal mucosa and the palatine glands].

Histologic findings of the palatal mucosa and the palatal glands of 73 patients with and without upper dentures were compared with distinctive marks, complaints and clinical diagnoses as well as with the secretion of the minor salivary glands. Patients complaining of oral burns show the same rate of patho-histologic findings as those without any complaints. Inflammation and atrophic reactions of the palatal mucosa and the palatal glands do not reduce the secretion rate of the minor glands. In these cases, however, considerable changes of the quotient exist between sodium and potassium ions of the palatal saliva secretion. Signs of inflammation of the palatal tissues were seen more frequently in full denture wearers and especially in those wearing upper dentures during day and night. Causative factors of denture incompatibility are discussed.

Burning Mouth Syndrome↗
PubMed1990

[Reactions of the oral mucosa to mechanical load stimuli from dentures].

The oral mucosa is the primary medium bearing removable dentures. Problems of adaptation and incompatibility of denture bases borne by mucosal tissues first of all arise at the mucosa covering the palate and the alveolar ridges. Depending on its functional qualities, the denture bearing mucosa more or less fulfills the task of buffering chewing forces acting on the denture base and distributing them on the bone surface. Studies on physiological and morphological reactions of the denture bearing tissues resulting from mechanical stresses show that the mucosa is entirely capable of tolerating short-term pressures during chewing. In this connection the increase in the thickness of the denture bearing mucosa must be considered as a physiological response to mechanical load.

Bite Force↗
PubMed1990

[Biometric studies on implanted and natural abutments].

The mobility of 50 osseointegrated implants, inserted for improvement of the support of dentures in edentulous lower jaws, was studied during a period of up to 3 years by means of mechano-electronic measurements. The results showed that 3 months after implantation osseointegrated implants have less quasi-static mobility than natural teeth without periodontal lesions. Under the stresses of mastication the mobility of osseointegrated implants continuously increases. After 2-3 years, implants show a similar mobility as natural teeth supporting comparable denture constructions. The Periotest readings of implants were significantly lower than those of natural teeth, largely independent of the date of mobility measurement. A prognosis of functional properties as well as predicting the impending loss of osseointegrated implants is possible with the aid of long-term mobility measurements.

Aged↗
PubMed1989

Localization of epithelial markers and defence proteins in minor and major salivary glands.

Immunohistochemical demonstration of cytokeratin (CK), tissue polypeptide antigen (TPA), carcinoembryonic antigen (CEA), lactoferrin (Lf), lysozyme (Ly) and secretory component (SC) was performed in major salivary glands (MaSG), labial and palatal salivary glands (LSG, PSG). CK and TPA were demonstrated in ductal cells of all SGs. In addition, binding of anti-CK (Mw-56 Kd) antibody (AB) KL I was seen in all serious acini of MaSG, basophilic acini and demilunes of LSG and in some mucous acini of PSG. Binding of anti-CK (Mw 44-54 Kd) AB-PKK I, another polyclonal anti-CK (Mw 55-67 Kd) AB-PCK and anti-TPA AB was demonstrated in all basophilic acini of LSG, basophilic portions of mucous acini in PSG and not in acini of MaSG. Significant differences were observed in the expression of CEA, Ly, Lf and SC between acini of MaSG and MiSG which probably reflects different functions of these glands.

Antibodies, Monoclonal↗
PubMed1989

[Quantitative studies on the secretory output of the palatine salivary glands].

A method for the direct measurement of the secretory output of the palatine glands is described and its clinical reliability is verified in a study on 134 persons. The results showed that, if the measuring conditions are fulfilled and the measuring parameters are kept constant, the error remains below 15%. Situative influences, such as the time of the day, the date of the measurement, etc. are just of secondary importance for the measured results. The physiological secretory output of the palatine glands averages 1.36 microliters/mm2 mucosal surface, which is about 30 times as much as the values measured in patients with symptoms of hyposalivation. Personal characteristics of the persons tested such as age, sex, etc. have no major influence on the secretory output. Serial measurements during treatment with ptyalagogues supported the evidence that this measuring method is a valuable instrument in the diagnosis of salivation disorders.

Humans↗
PubMed1989

[Quantitative comparison of the secretion of salivary and mucous glands].

The flow rates and the Na+/K+ quotients of the saliva from the parotid and palatine glands were determined by direct comparison in 121 patients. The results showed that the flow rates and the Na+/K+ quotients of the same types of glands were not correlated with each other. Pronounced and specific interrelations as to the amount of secretion were observed only in patients complaining about dry mouth or smarting of the mucosa or patients under chronic treatment with psychoactive drugs where secretory inhibition is a side effect. The evaluation of the Na+/K+ quotients demonstrated that the secretion examined was almost exclusively resting saliva secretion. Based on these observations it is important that our understanding of the control mechanisms governing the activities of the different gland types within the masticatory system be reassessed.

Adult↗
PubMed1989

[Studies on the mechano-electronic measurement of tooth mobility].

The correlations between dynamic and quasi-static mechano-electronic measurements of tooth mobility were investigated in more than 1500 teeth. The two methods correlate quite well with the conventional classification (in Germany). On the other hand, there is no correlation between dynamic and quasistatic mechano-electronic measurements. Nevertheless distinctive signs and periodontal findings could be verified by mechano-electronic evaluation of tooth mobility.

Dental Stress Analysis↗
PubMed1988

Immunohistochemical study of palatal salivary glands of denture wearing patients.

The binding pattern of antibodies against different cytokeratin (CK) polypeptides, tissue polypeptide antigen (TPA), carcinoembryonic antigen (CEA), lactoferrin (Lf), lysozyme (Ly) and secretory component (SC) in palatal glands (PSG) of long-term denture wearing patients has been studied to investigate immunohistochemically the localization of these marker proteins in normal PSG and in denture-induced sialadenitis of PSG. The study included palatal gland biopsies from 28 patients (15 f, 13 m; mean age 59 years), 17 of them with normal PSGs, 8 with focal obstructive sialadenitis, and 3 with diffuse sialadenitis. Presence of CK and TPA was found in all intra- and extraglandular salivary ducts, in the basophilic portions of acini, in some mucous acini, and in all atrophic acini. Increased expression of CEA and Lf was observed in inflammed areas of PSG which, on the other site, were devoid of Ly and SC. In the mucous acini of healthy PSG considerable basal Ly immunoreactivity was seen. SC was localized in almost all ductal cells and in some acinar cells. Appearance of Lf in the ductal cells of PSG indicates an early sign of palatal sialadenitis. Some distinctions in the expression pattern of the marker proteins between the mucous acini of major salivary glands and PSG point to differences in the functional activities of either group of salivary glands.

Denture, Complete, Upper↗