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At least 811 records · Page 45Linked to original sources
PubMed2006

Effects of some antiepileptics on septal-kindled seizures in rats.

PURPOSE: The present study was performed to understand the characteristics of septal kindling in rats, especially the efficacies of antiepileptic drugs in comparison with amygdala kindling. METHODS: Under pentobarbital anesthesia, rats were fixed to a stereotaxic apparatus, and electrodes were implanted into the right frontal cortex, the hippocampus, the lateral septal and the amygdala. Electrodes were connected to a miniature receptacle, which was embedded in the skull with dental cement. Bipolar stimulation was applied to the lateral septal or the amygdala every day until a generalized seizure was obtained. Carbamazepine (CBZ), zonisamide (ZNS) and clobazam (CLB) were orally administered to fully kindled rats. RESULT: A considerable number of stimulations was required to establish septal-kindled seizures. In addition, wet dog shakes were observed during the septal kindling procedure, different from amygdala kindling. The oral administration of CBZ, ZNS and CLB caused a dose-dependent inhibition both of seizure stage and after-discharge (AD) duration of septal-kindled seizures. CBZ and ZNS caused a more potent inhibition of septal-kindled seizures than amygdala kindled seizures, whereas CLB inhibited both septal and amygdala kindled seizures to almost the same extent. CONCLUSION: Septal kindling was confirmed to possess some characteristics, which were evidently different from that of amygdala kindling. In addition, it was demonstrated that septal kindling was also available as a model for the evaluation of antiepileptic drugs.

Amygdala↗
PubMed2005

[Ozone therapy with the OzonyTron apparatus].

PURPOSE: OzonyTron is one of the newest devices for the generation of ozone. The aim of this study was to assess the benefits of ozone in some pathologies. MATERIAL AND METHODS: Ozone therapy was used in 20 patients, including eight with lip herpes, five after dental surgery and chiseling of third molars, six with seborrheal inflammation of facial skin and one with mycosis of the toes. RESULTS: Treatment with OzonyTron is noninvasive and painless. The oxidative properties of ozone are exploited to combat microbial infection. Thus, the device is valuable primarily for its antiseptic action. Following ozone therapy, a very good effect was observed in each case.

Anti-Infective Agents↗
PubMed1997

Investigation of the integration process of dental implants by means of a numerical analysis of dynamic response.

OBJECTIVES: The aim of this work was to present a preliminary numerical analysis of the integration process of dental implants using a finite element simulation of the dynamic response following impulse excitation. Assessment of the osseointegration process has been previously examined using a numerical approach by calculating the natural frequency of a cantilever attached to the implant. The methodology adopted in this work allows a direct measurement of the implant response following impulse loading and avoids the addition of a bulky cantilever set-up. METHODS: The geometric configuration was obtained by averaging the coordinate data from tomographic scans of 14 mandibles. The materials properties were approximated from experimental analysis performed on trabecular and cortical bone tissue. A load was applied to the top of the implant in one direction resulting in an initial displacement. The implant was then freed and allowed to vibrate over approximately 10 cycles. Three fixity conditions were assumed by changing the properties of the surrounding bone ranging from full integration to a poorly integrated implant typical of the situation during bone healing following surgery. The results of the three fixity conditions were compared by calculating the fundamental displacement amplitudes and frequencies of the vibrating impact. RESULTS: The calculated results indicated that the implant vibrated at a predominant frequency when partially integrated with a displacement principally in the direction of the applied impulse. However, when the implant was fully integrated a more complex vibration pattern ensued, suggesting the superposition of two or more fundamentals. SIGNIFICANCE: Attention has been paid to the formulation of the numerical model for validation purposes as well as a reliable reference for the optimum interpretation of the experimental data. In this way it was possible to establish a simulation procedure to investigate the response of the tissues surrounding the implant and their properties at different stages of healing. It should be pointed out that the numerical procedures represented a valid preliminary approach to the problem and were capable of indicating a guide to the optimum design of the experimental apparatus for measurement of displacement and frequency in vivo.

Alveolar Process↗
PubMed2004

A technique for long-term implantation of a microcatheter into the third ventricle of post-pubertal Chinese Meishan pigs based on ventriculography.

The objectives of this study were to implant a microcatheter into the third ventricle of post-pubertal Chinese Meishan pigs, and to maintain the microcatheter for a long time without causing stress. Fourteen pigs (45-60 kg BW) were used. Each pig was anesthetized and the head was orientated on the stereotaxic apparatus. A radiopaque dye was placed into the ventricle via a guide cannula inserted 3.5 mm forward of the bregma. A microcatheter was inserted into the third ventricle using ventriculography, and fixed with dental cement to a metal-mesh protector and screw anchors embedded into the skull. The opposite end of the microcatheter was externalized from the dorsal neck so that corticotropin-releasing hormone (CRH) could be injected easily. Simultaneously, a catheter was fitted in the jugular vein, and the free end of the catheter was externalized from the dorsal neck. Microcatheter-implanted pigs showed a normal progesterone concentration profile, and a constant cortisol level during at least two estrous cycles. Furthermore, intracerebroventricular injections of CRH (25 microg/500 microl) resulted in an increased plasma cortisol concentration (P < 0.05). Thus, the technique developed in this study enables us to approach the third ventricle in post-pubertal freely-moving pigs effectively over a long time, without causing stress.

Animals↗
PubMed1985

Pressures recorded during periodontal pocket irrigation.

Pressures arising during periodontal pocket irrigation with 5 ml and 20 ml disposable plastic syringes, a peristaltic pump and a Waterpik pulsating irrigator were measured with an in-line transducer and recorder in 11 patients. Three types of needles were used with each device; disposable 15-gauge straight and angled needles and a 15-gauge angled reusable needle. Measurements were made with the needle tips just within, and 3 mm into the pocket. With both the 5 ml and 20 ml syringes and all needles, pressures of 100- to 500-mm mercury were recorded. With the peristaltic pump, pressures of 70- to 340-mm mercury were recorded with all needles. The Waterpik apparatus produced pressures of not more than 60-mm mercury in all cases.

Dental Devices, Home Care↗
PubMed1990

[Fragmentation of sialoliths].

An in vitro experiment proved that a sialolith can be disintegrated, but that also serious damage is caused to the teeth and dental restorations. Therefore, no experiment was carried out on a patient, although it proved to be possible to position a patient on a lithothriptor in a way that the shock wave of the apparatus would hit the sialolith without passing the brain, eyeballs and laryngeal skeleton.

Humans↗
PubMed1994

Intracoronal bleaching: concerns and considerations.

The history of intracoronal bleaching and the development of the walking bleach technique are reviewed. External cervical resorption associated with intracoronal bleaching is a serious sequela that has been reported in the literature. One explanation given for this phenomenon is that it results from an inflammatory process initiated by the presence of bleaching agents in the attachment apparatus. The basis for this conclusion is discussed. A review of published case reports on external cervical resorption associated with intracoronal bleaching revealed that: 100 per cent of the affected teeth had no intermediate dental base placed, 84 per cent were treated with a thermocatalytic technique, 80 per cent were bleached after the root canal sealer was fully set and 72 per cent had a history of trauma before bleaching. Based on these observations, it should be possible to safely bleach teeth intracoronally provided specific concerns and considerations are taken into account. These are: 1) the use of heat should be avoided; 2) an intermediate dental base should be placed with due respect to the attachment level; and 3) a base should be selected with due respect to its effectiveness in sealing tooth structure.

Borates↗
PubMed1995

A laboratory model for dental radiographic studies.

Though a number of laboratory models have been developed to study the effects of X-ray geometry on the appearance and relative positions of anatomical landmarks, such as the amelocemental junction and alveolar crest, many have failed to take into account the three-dimensional nature of the alveolus and its spatial relationships with the teeth. As a result, the findings of many ex vivo investigations must be questioned. The aim of this investigation was to develop and refine a new laboratory method for experimental dental radiography utilizing a series of anatomical radio-opaque acrylic models containing extracted teeth. The method allows adjustment of the beam-object relationship through the use of precision-made wedges, which are able to tilt the models through a series of angles thus simulating in vivo changes in both vertical and horizontal X-ray beam angulation. The technique is capable of being used in studies involving assessment of alveolar bone height or the depth of carious lesions. The precision of the method was tested by radiographing in nine different positions a test device consisting of four small amalgam fillings embedded in a perspex sheet. Following removal and replacement, exposures of the test device were repeated for each position. Five linear distances between pairs of fillings were selected and measured on each radiograph to give a total of 45 measurements per set of films. There was exact agreement in 39 of the measurements recorded and a discrepancy of +/- 0.1 mm in the remaining six. The estimated standard deviation for variation on repeat radiography was 0.258 and the 95% confidence interval 0.214 to 0.325. The precision of the apparatus was thus found to be adequate for the measurement of differences in small distances.

Acrylic Resins↗
PubMed2004

Cross-sectional analysis of different variables of patients with non-insulin dependent diabetes and their periodontal status.

The periodontal condition of 72 non-insulin dependent diabetes patients was compared with that of 92 nondiabetic individuals. Plaque Index (PII), Calculus Index (CI), Gingival Index (GI), and attachment loss (AL) were measured on four surfaces of six teeth in each subject. All four parameters were significantly higher in the diabetic group. No significant difference in the frequency of toothbrushing was found between the groups. For all age groups, GI and AL were higher in the diabetic group. In each group, GI was not changed with age, while AL increased with age. Classification of the groups based on PII showed that the diabetic group's GI was higher than the nondiabetic group for low, medium, or high PII values. The diabetic group showed higher AL for only the medium and high PII groups. Classification by CI revealed that the diabetic group's GI and AL were significantly higher than those of the nondiabetic group for subjects with low, medium, or high values of CI. Multiple regression analysis revealed that the main factor affecting GI was the presence or absence of diabetes. PII and CI both showed a significant relationship with GI; age was the second most significant factor. The most significant factors influencing AL were CI and the presence or absence of diabetes; age was the second most significant factor. Patients who had had diabetes for more than 10 years had a higher AL than those who had suffered from diabetes for less than 10 years. Patients with average HbA1c values > or = 10% had more serious mean GI values than those with HbA1c values < 10%. In patients with diabetes, age, plaque accumulation, and calculus formation have more detrimental effects on the periodontal apparatus than in healthy individuals.

Age Factors↗
PubMed1995

Biomechanics of occlusion and the articulator.

The evaluation of the occlusion is important in prosthodontics and restorative dentistry because the occlusal surfaces of the teeth to be restored must be functional units of the patient's stomatognathic system. Specifically, the morphology of the cusps, fossae, grooves, and marginal ridges should support the mandible in the intercuspal position and where appropriate, during eccentric jaw movements and in functional activities such as mastication. Restored teeth should not interfere with mandibular function in mastication, speech, and swallowing nor should they transmit excessive force to the attachment apparatus or the temporomandibular joint either in the intercuspal or eccentric jaw positions or during movement.

Biomechanical Phenomena↗
PubMed1975

[Cellular responses to vibration during dental drilling with belt drive motor engine (in vitro) (author's transl)].

There have been many reports on the pulpal reaction caused by vibration during high speed dental drilling with air turbine hand-piece. It is, however, not clear pulpal responses to vibration of low speed drilling with 7 000 rpm of belt drive motor engine which produces a fundamental vibration of about 170 cps having most unpleasant sensation at vestibular apparatus. Here, cellular responses of L strain cells to vibration derived from 7 000 rpm and 15 000 rpm of belt drive motor engine were observed in vitro system. There is no difference between the both cellular responses to the vibration of 7 000 rpm and 15 000 rpm. Suspended free cells were easily influenced and degenerated by the vibration, and remarkably checked in their cell-multiplication. On the contrary, in the cells adhered to the substratum of glassware, no degeneration and no inhibitory effect were observed. And the cells showed reversible response of cytoplasmic shrinkage only.

Cell Adhesion↗
PubMed1990

[Thermal diffusivity of dental cements].

Thermal insulative efficiency, is one of the desirable properties of the dental cements. In this study, the thermal diffusivity of three types of dental cements, were measured. Thermal diffusivity was determined by the following method. Two thermo-couples were used and connected to a chart record, the first was embedded in the cylindrical block of the cement specimen and the other in a mixing of ice and water (reference thermocouple). All them were set in a apparatus consisting of a double cooling bath. Calculation of thermal diffusivity were based on the curve provided of the record during cooling of the cement and a theoretical mathematic model. Values were ranged from 2,985 to 3,934 cm2.sec-1. ZOE cement exhibited the highest value, the glass-ionomers the lowest and the poly-carboxylates were average. The results showed that the thermal diffusivity of the cements is dependent from the type of the cement but the differences between them were not statistically significant. Additionally, the values obtained were about the same as the dentin, so the dental cements may consider as good thermal insulators.

Dental Cements↗
PubMed2003

Relative wear of enamel opposing low-fusing dental porcelain.

PURPOSE: This study evaluated the wear of human enamel opposing 5 low-fusing dental porcelains and a traditional feldspathic control. In a second experiment, the repeatability of the test method and the effect of ceramic overfiring on enamel wear were also evaluated. MATERIALS AND METHODS: Five low-fusing dental porcelains--Finesse (FI), Rhapsody (RP), IPS d.Sign (DS), Omega 900 (OM), and Duceram LFC (LFC)--and 1 traditional feldspathic porcelain--VMK 68 (VMK)--were formed into disks (n = 10) and used as substrate for the wear test. Enamel was harvested from extracted human molars and machined into cusps with a 5-mm spherical radius (n = 60). The Oregon Health Sciences University oral wear simulator was used to simulate chewing and the size of the resulting enamel wear facets (in mm(2)) were evaluated after a specified number of chewing cycles. A portion of the experiment was duplicated to assess the repeatability of the data and determine the effects of overfiring on enamel wear. Data were subjected to analysis of variance and post hoc tests to determine significant differences. After wear testing, scanning electron micrographs were made using representative ceramic samples from each group. RESULTS: The results indicate that none of the low-fusing ceramics resulted in significantly less wear than the VMK control. In fact, 3 of the low-fusing porcelains (OM, RP, LFC) resulted in significantly greater enamel wear than VMK. Enamel wear was not significantly affected (p = 0.29) by the increased ceramic firing temperature. Wear data were repeatable, with no significant difference (p = 0.56) between the enamel wear from 2 separate experiments. The results from both experiments indicated that ceramic material significantly affected enamel wear (p <0.001). There was significantly less enamel wear opposite DS than LFC. CONCLUSIONS: This work suggests that variations in ceramic composition and microstructure may affect the opposing enamel wear, but that low-fusing temperatures do not necessarily guarantee low enamel wear. Although the clinical relevance of this testing apparatus may be questioned, the testing method was repeatable.

Aluminum Silicates↗
PubMed2002

A note on the temperature dependence of the flexural strength of a porcelain.

OBJECTIVES: The purpose of this study is to determine the temperature dependence of the flexural strength of a dental porcelain (IPS-Classic Dentin; manufacturer: Ivoclar, Liechtenstein) with temperature between its glass transition (T(g) = 581.7 degrees C) and room temperature. METHODS: The flexural strength was measured in three-point bending tests on an Instron 4204 testing apparatus. The strength values were determined for the temperatures T = 20, 300, 400, 450, 500, 550, and 600 degrees C. RESULTS: In the temperature interval 20 < or = T < or = 400 degrees C the flexural strength decreased slightly from approximately 80 to approximately 73 MPa (mean values), as temperature increased. That is a decay of less than 10%. At higher temperatures the flexural strength increased to a maximum of approximately 98 MPa at 500 degrees C, probably due to the closure of microcracks in the surface on account of the onset of viscous flow. A further increase of the temperature delivered again decreasing strength values. At its glass transition temperature the porcelain's flexural strength was approximately 76 MPa which is only about 5% less than the value at room temperature. SIGNIFICANCE: In order to be able to evaluate the risk of fracture of ceramometallic crowns and bridges due to high temperature gradients and accompanying large transient thermal stresses in the veneer during the fabrication process, flexural strength values at high temperatures must be known. This study was carried out to fill this knowledge gap because to the authors' knowledge there was little published in the literature.

Aluminum Silicates↗