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At least 451 records · Page 25Linked to original sources
PubMed1980

Tooth extractions and sick sinus syndrome.

The experience of tooth extraction in four patients with sick sinus syndrome (SSS) is described, and electrocardiographic features and a guideline for dental extractions are discussed. Patients controlled by medical therapy were safely treated under administration of an effective drug prior to treatment, while patients with a cardiac pacemaker were examined and checked on the apparatus before tooth extraction by their own specialist. After freedom from the cardiac problems, dental extractions were done smoothly. Electrocardiographically, in the cases with pharmacological treatments, either normal sinus rhythm revealed after additional administration of isoproterenol, or more severe bradycardia-tachycardia pattern was shown immediately after tooth extraction. In the patients with a cardiac pacemaker, ECG presented patterns controlled by pacemaker but beats rose from their own sinus node in the anesthesia-extraction procedure with various grades.

Adult↗
PubMed1993

[The interrelationships between dental parameters and electronic axiographic findings. A study on subjects with nonphysiological incisor relations].

The purpose of the present study was to discern possible relationships between dental parameters and the horizontal inclination of the condyle path. Two test groups of orthodontically untreated individuals with non-physiological incisor relationships, one group with enlarged and the other with reverse overjet, were selected for the study. An opto-electronic apparatus was employed to measure the horizontal inclination of the condyle path. The dental parameters were set by clinical examination and by measuring plaster casts. Both groups exhibited significant distribution deviations in the inclination of the condyle path and in the following parameters: "occlusal contacts of the front teeth during protrusion", "overbite", "resulting overjet", and "sagittal and vertical distance of the incisal edge of the lower incisors to the zero point of the upper incisors". Statistically no correlation between the dental parameters and the inclination of the condyle path was discerned. The influence of muscular guidance is in large measure the determining factor for the large variations in the TMJ registrations, and especially in their quantitative evaluation. The results were the same even when tracings were repeated a number of times with the same patient.

Adult↗
PubMed1961

The ultrastructure of ameloblasts during matrix formation and the maturation of enamel.

Ameloblasts from different regions of upper incisors of rats were examined with the electron microscope. During matrix formation, the cells resemble secretory cells. They are extremely long, tightly packed, and show considerable polarity. Nuclei are at the basal end of the cell. Mitochondria are proximal and the Golgi apparatus distal to the nucleus. Ergastoplasm is found in all levels but mainly in the distal end. A terminal bar apparatus separates the distal end of the cell from Tomes's process. Next to this is soft enamel. The next incisal region is a transitional zone in which the ameloblasts separate easily from the enamel. Endoplasmic reticulum is dilated and very obviously in communication with the perinuclear space. Mitochondria are present not only proximal, but also distal, to the nucleus. The next incisal zone consists of cells related to the maturation of enamel. They no longer resemble secretory cells, but now have more characteristics of transporting cells. Processes from the distal end of the cell are present with mitochondria closely applied to the base of the processes. A considerable amount of intercellular space exists with microvilli projecting into the space. Iron granules appear in these cells, and the ergastoplasmic cisternae are dilated. In the incisal end of this zone, the iron granules form aggregates. The iron finally leaves the cells to enter the enamel. Free RNP particles and fibrils become more evident after the iron leaves the cells. In the most incisal region, the ameloblasts are further reduced in height. Distal processes are no longer present and fibrils are more conspicuous.

Ameloblasts↗
PubMed2004

Puncture resistance and stiffness of nitrile and latex dental examination gloves.

OBJECTIVE: The aim of the current study was to assess the puncture resistance and stiffness of nitrile and latex dental examination gloves. METHODS: Puncture resistance was measured by employing an adapted version of ASTM F1342-91 using both a 316 stainless steel puncture probe (0.8 mm diameter) and a dental injection needle (0.45 mm diameter) interfaced to a tensile testing apparatus. Glove specimens (12 cm length, 1.5 cm breadth) were removed for modulus (M100) evaluation by assessing the force required to elongate the specimen to 100% of the original length. Glove samples were also aged to investigate whether puncture resistance and M100 values varied with aging at 70 degrees C for 7 days in an air-circulating oven. RESULTS: The nitrile glove types were assessed to have significantly higher puncture resistance compared with the latex glove type when the steel puncture probe was the pentrometer when using the one way analysis of variance (ANOVA) at the 95% significance level. Interestingly the puncture resistance for the latex glove type was significantly higher (P < 0.001) when a dental injection needle was used as the pentrometer compared with the nitrile glove types. The M100 values were significantly higher for the nitrile glove types for which the stiffness increased when the gloves were aged (P < 0.001). CONCLUSIONS: The higher stiffness values resulted in increased puncture resistance when the nitrile glove specimens were aged irrespective of the pentrometer type. However, the ability of latex to re-seal itself on puncture may be beneficial when considering the protection potential of each glove type against breaches in cross infection. For clinicians that have experienced an adverse reaction to natural latex gloves, the results of the current study indicate that nitrile gloves are available at reasonable cost and offer the clinician comparable resistance to puncture with latex gloves.

Analysis of Variance↗
PubMed1994

A study of water flow efficiency in dental air/water syringe tips after repeated chemiclave sterilization.

In response to the need for dental office asepsis, many practitioners sterilize dental air/water syringe tips for each patient. It is hypothesized that repeated sterilization would lead to internal corrosion restricting the water flow. This study was conducted to evaluate consistency of water flow in a series of dental air/water syringe tips after multiple cycles of Chemiclave sterilization. An apparatus was constructed to deliver water at the same pressure and flow to each syringe tip. The flow rates between tips were significantly different (P < .001). Average water flow, in grams per minute, was determined by ten repeat trials for each tip. The tips were retested after 1, 5, and 25 cycles of Chemiclave sterilization. None of tips showed a decrease in water flow efficiency after repeated sterilization cycles. No difference in ability to remove etchant from enamel and dentin could be demonstrated using a 10-second wash.

Acid Etching, Dental↗
PubMed1983

[Functional anatomy of the blood vessels of the dental pulp in the white rat].

Applying a complex of modern microangiological techniques, the organization of the blood bed in the incisor and molar pulp has been studied in the white rat mandible. Production of the dental tissue components in the zones of dentinogenesis is ensured by an increased density of the capillary and venular bed of the pulp, a tight connection of the capillaries with predentin. The morphometric data obtained make it possible to prognosticate a high intracapillary pressure and the hydratation degree of the interstitial gel in the incisor pulp, which is close to maximal figures. Differences in angio-architectonics of the incisor pulp and the molar pulp depend on the peculiarities of the histostructure and functional state of the pulp, on the geometry of the dental cavity and the radicular canals. The pulp blood bed possesses a complex apparatus that ensures the blood stream regulation (duplication of the nutrition sources, arteriolar and venular area, various types of anastomoses, precapillary sphincters and others).

Animals↗
PubMed1980

Dental and social effects of malocclusion and effectivenessof orthodontic treatment: a review.

The relationship between malocclusion and the health of the masticatory apparatus is reviewed. While there is evidence that certain features such as traumatic deep overbite, unprotected incisors and impacted teeth may adversely affect the longevity of the dentition, the relationship of dental irregularity to periodontal disease, caries and mandibular dysfunction is less certain. Studies in the field of social psychology indicate that an unattractive physical appearance may evoke an unfavourable social response in many facets of social interaction but the place of dentofacial anomalies in this context has not been satisfactorily assessed. The individual's adjustment to his own imperfections in dental alignment is variable and there is no evidence that children with visible irregulaities will in general be emotionally handicapped. Effectiveness studies have yet to be undertaken but the factors which will have to be taken into account in assessing the benefits of orthodontic treatment are the definition of treatment need, treatment standards, the disadvantages of treatment and the influence of other determinants of dental health. The need for further research is underlined.

Dental Caries↗
PubMed1991

[Density-temperature change on Ag-Cu binary alloys].

In order to investigate the density variance of casting dental alloys according to the change of temperature, a density measurement apparatus based on the sessile drop method was developed. This apparatus consisted of three parts: a furnace, a photo taking system and an image analyzing system. Five Ag-Cu binary alloys: Ag-3%Cu, Ag-15%Cu, Ag-28%Cu, Ag-70%Cu, Ag-97%Cu; were measured from room temperature to 1400 degrees C, and five graphs of Temperature-Density were drawn. From these graphs, densities, at room temperature, solidus point and liquidus point were obtained. Using this data, the solidifying shrinkage and the shrinkage in the solidus phase were calculated. The closer the composition of an alloy to pure metal the higher the solidifying shrinkage, and at the eutectic point the solidifying shrinkage showed the lowest value. It was observed that the metal texture influenced the value of solidifying shrinkage. There were no significant differences of thermal shrinkage in solidus between the five alloys, and each showed approximately 5vol% shrinkage. These values on high thermal condition are considered to be very important as fundamental data necessary for the manipulation of dental casting.

Copper↗
PubMed1997

A practical system for evaluating casting results in fixed restorations.

A practical and economical system of casting testers, formed by simple constituents that can be found anywhere, has been developed. Pattern formation is a quick procedure, and because the testers are small and imitate forms familiar to dental technicians, they can incorporate them easily into their daily work routine. Results can be interpreted without the use of any apparatus, because they are based on the principle of "all or nothing." The proposed system was field tested in 13 commercial dental laboratories, and the percentage of successes obtained affirmed that the goals of the procedure are attainable and valid.

Crowns↗
PubMed2004

[Research methods in dentistry 1. Methods to quantify retention of complete dentures].

Retention is not an unambiguous variable. The degree of retention is dependent on biologic and physiologic properties of a complete denture and the denture-bearing and surrounding tissues. Quantifying retention forces of a complete denture can be carried out with three types of methods: subjective methods, methods with clinical more or less objective criteria, and nearly entire objective methods using measurement equipment. The subjective and most of the methods with clinical criteria are not or little reliable. However, for epidemiological research the methods with clinical criteria are very pragmatic. Of all objective methods using measurement equipment, the gnathodynamometer is the only apparatus with proven reliability.

Dental Research↗
PubMed2005

Dental care with manual toothbrushes during fixed orthodontic treatment--a new testing procedure.

AIM: The aim of this investigation was to employ a new in-vitro testing system for manual toothbrushes in order to distinguish the more effective from those less so for dental care during fixed appliance treatment. MATERIALS AND METHODS: The testing apparatus consisted of a sliding carriage able to execute a horizontal brushing movement, and a row of artificial teeth upon which the various toothbrushes were manipulated. The artificial row of teeth was fixed on a sensor that recorded in all three dimensions the forces and moments caused by the toothbrushes on the toothbrush field. All the tests were executed with a weight of 110 g on a tooth field with a multibracket appliance. Tests were also carried out with five toothbrushes having weights of 200 g, 250 g and 300 g. Here, the decisive target values were 1) the degree of exertion necessary in the brushing direction to move a brush over the artificial teeth, and 2) the maximum force occurring in the brushing direction. High target values indicated high interaction between toothbrush bristles and the surfaces being brushed. RESULTS: From testing five toothbrushes with four different weights, we have established profiles confirming the beneficial and less beneficial properties of certain toothbrushes involving various high contact forces.

Dental Devices, Home Care↗
PubMed1980

Time-temperature behavior for creep of dental amalgam.

From 0 to 24 hours at an initial static stress of 34.5 MPa and in the temperature range of 0 to 60 degrees C, the creep behavior of four different one-week-old dental amalgams was monitored in a recently developed mini-specimen creep apparatus. In most instances the behavior could not be described by a linear relationship. Therefore, the usefulness of calculating creep rate based upon only two times, i.e., 1 and 4 hours, must be questioned. On the other hand, the observed creep kinetics were found to follow accepted nonlinear models of dislocation/obstacles interactions which may be thermally activated.

Cold Temperature↗
PubMed1987

Monoclonal antibody and immunogold cytochemical localization of amelogenins in bovine secretory amelogenesis.

Amelogenin enamel-protein epitopes in developing incisors were ultrastructurally localized with high specificity resolution. They formed clumps scattered over the enamel organic matrix between the hydroxyapatite crystals, and were also present over islands of stippled or granular material at the forming surface of the enamel matrix demonstrating that this material consists in part of amelogenin enamel protein. The amounts of amelogenin, as judged by labelling density, were not greater in the stippled or the surface crystal-containing matrix as compared to the enamel matrix up to 50 micron deep. Amelogenins were also localized in the rough endoplasmic reticulum. Golgi apparatus and secretory granules of the ameloblasts, which suggests they are merocrine secretions.

Amelogenesis↗
PubMedDate not supplied

[Technical equipment for oral radiography].

Listed problems of dental roentgenography and technical characteristics of dental roentgenological equipment used in the Soviet stomatology demonstrate a lot of disadvantages. The principles of apparatus design need the improvements, indicated in the paper.

Equipment Design↗
PubMed1994

Ultrastructure of cementogenesis as affected by growth hormone in the molar periodontium of the hypophysectomized rat.

To document the effect of hypophysectomy and growth hormone replacement on the ultrastructure of cementogenesis in the developing rat third molar, 12 female Wistar rats were randomly allocated to normal control, hypophysectomized or hypophysectomized plus human growth hormone (for 10 days) treatment groups. The results of this study by electron and light microscopy and morphometry have shown that qualitative and quantitative changes occur in the organelles of cementoblasts forming cellular cementum as a result of hypophysectomy and growth hormone replacement. After hypophysectomy, the changes of less prominent nucleoli and nuclear pores, less prominent Golgi apparatuses and decreased endoplasmic reticulum can be interpreted as diminished cementum matrix biosynthesis--an interpretation that can be confirmed morphometrically by less cellular cementum formation. Growth hormone replacement for 10 days reactivates protein synthesis and cementogenesis as evidenced by ultrastructural changes in cementoblasts and a greater production of cementum.

Animals↗