Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “DENTAL APPARATUS”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 865 records · Page 48Linked to original sources
PubMed1993

Effect of salivary components on dissolution rates of carbonated apatites.

Salivary pellicle has been reported to retard the acid-induced demineralization of dental enamel. However, this effect has not been quantified, nor has the direct protective effect of pellicle on carbonated apatite dissolution been elucidated. We have developed a model capable of further studying these questions. Well-characterized synthetic ceramic carbonated apatite discs were pretreated with parotid or whole salivary secretions for 18 h or 7 days and then challenged with 0.1 mol/l acetate, pH 5.0, in a dissolution apparatus. Surface dissolution rates were compared to those from the same carbonated apatites with no saliva pretreatment. Pellicles formed from whole and parotid saliva in vitro and whole saliva in vivo were capable of reducing surface dissolution rates of ceramic carbonated apatites by up to 83% but the degree of this reduction was dependent on the type of saliva and the conditions of pretreatment.

Adsorption↗
PubMedDate not supplied

Systemic conditions associated with periodontitis in childhood and adolescence. A review of diagnostic possibilities.

The term periodontitis is used to describe a group of multifactorial diseases that result in the progressive destruction of the structures that support the teeth within the jaws, the so-called attachment apparatus, which includes the periodontal ligament, cementum and alveolar bone. If left untreated, this process can ultimately lead to tooth loss. The pathogenesis of these diseases involves the initial colonization of the gingival microenvironment of a susceptible host by pathogenic bacteria found in dental plaque. Subsequently, much of the tissue destruction characteristic of periodontitis is a , by-product, of the host response directed against these organisms. One of the major factors that appear to modulate disease severity is systemic health. Severe periodontitis in young individuals can therefore be a manifestation of an underlying systemic disease. In this review we will discuss the most important systemic diseases that should be considered in a differential diagnosis when evaluating a pediatric patient presenting with periodontitis.

Adolescent↗
PubMed1990

Influence of colchicine on the addition of a sugar to the enamel protein in secretory ameloblasts of cultured germs of rat molar tooth by 3H-galactose radioautography.

The influence of colchicine on the addition of 3H-galactose to the enamel protein in secretory ameloblasts of cultured germs of rat molar tooth was investigated by light- and electron-microscopic radioautography. In tooth germs cultured without colchicine, the reaction products of 3H-galactose were observed over Golgi cisternae at early chase times and then localized over the enamel with time. In tooth germs cultured with colchicine, the silver grains were seen over the Golgi cisternae, condensing granules and accumulated secretory granules. Some grains also appeared with time over the pale granular material precipitated in the intercellular space with colchicine treatment. In quantitative analysis with light microscopic radioautography, values of silver grain counts over the unit area (100 microns2) on ameloblasts and enamel of colchicine-treated tooth germs were significantly lower at both 0 min and 30 min chase after 30 min pulse than those of control tooth germs, respectively. This finding indicates that colchicine diminished the incorporation of 3H-galactose into the secretory ameloblast of cultured tooth germs. It is suggested that colchicine decreases the activity of the Golgi apparatus with regard to the addition of sugar to the synthesizing glycoprotein in the secretory ameloblast.

Ameloblasts↗
PubMed2003

Evaluation of periodontal regeneration following grafting intrabony defects with bio-oss collagen: a human histologic report.

This study evaluated the clinical, radiographic, and histologic response to Bio-Oss Collagen when used alone or in combination with Bio-Gide bilayer collagen membrane for the treatment of four intrabony defects (5 to 7 mm) around single-rooted teeth. After reflecting a full-thickness flap, thorough degranulation and root planing were accomplished. In all cases, Bio-Oss Collagen was then used to fill the defects, and in two cases, a Bio-Gide membrane was placed over the filled defect. Radiographs, clinical probing depths, and attachment levels were obtained before treatment and immediately preceding en bloc resection of teeth and surrounding tissues 9 months later. Reduction in pocket depth and gain in clinical attachment level were observed for both treatment protocols. The histologic evaluation demonstrated the formation of a complete new attachment apparatus, evidencing periodontal regeneration that varied with defect morphology. This human histologic study demonstrated that Bio-Oss Collagen has the capacity to induce regeneration of the periodontal attachment apparatus when placed in intrabony defects.

Alveolar Bone Loss↗
PubMed1994

[Headgear-free molar distalization].

The difficulty in treating dentoalveolar class II disharmonies is briefly outlined. An innovative treatment method is presented which makes possible a distalization without the use of headgear. In the treatment method bands are cemented on the first molars, next impressions are made of the upper and lower dental arch, and then the impressions are poured with plaster. Following this the models are mounted in centric relationship in an articulator and the bite is opened 2 mm to 3 mm, so that the molars can be moved without making occlusal contact. The apparatus, an acrylic splint, is constructed in such a fashion as to cover the palatal surfaces from 2nd premolar to 2nd premolar. In addition, the premolars are also covered occlusally and buccally and the canine tips and the incisal edges are covered labially. A headgear tube is attached at the buccal surface in the premolar region of the acrylic splint. This acrylic splint, which is itself retentive, is cemented using glass ionomer cement. Combining this apparatus with a modified Nance Button makes it possible to establish an anchoring segment which is able to retain its position in the face of molar distalization. Molar distalization is then performed using a 0.032 inch stainless steel wire, which is placed between the headgear tube of the acrylic splint and the headgear tube of the band of the first molar. Highly elastic nickel-titanium open coil springs are used as the force elements.

Acrylates↗
PubMed1999

Developmental regulation and ultrastructure of glycogen deposits during murine tooth morphogenesis.

The distribution and ultrastructure of glycogen deposits were investigated in the murine tooth germ by histochemical periodic acid-Schiff (PAS) staining and transmission electron microscopy. Lower and upper first molars were examined in mouse embryos at embryonic days 11.5-17 (E11.5-E17) and in 2-day-old postnatal (P2) mice. The oral and dental epithelia and the mesenchymal cells were generally PAS-positive during tooth morphogenesis. PAS-negative cells were present at E13 in the distal tip of the tooth bud epithelium and in the contacting mesenchyme, and this complete lack of PAS reactivity continued in the dental papilla mesenchyme and inner enamel epithelium during the cap and bell stages. The lack of glycogen deposits in the interacting epithelium and mesenchyme during early morphogenesis may be associated with their demonstrated high signaling activities. Mesenchymal cells in the dental follicle consistently possessed small clusters or large pools of glycogen, which disappeared by P2. Since an intense PAS reaction was seen in mesenchymal cells at future bone sites, the glycogen in the dental follicle cells may be associated with their development into hard-tissue-forming cells. Ultrastructural observation of the enamel organ cells from the cap to early bell stages (E14-E15) revealed the occurrence of glycogen pools, which were associated with the Golgi apparatus and with vesicles having amorphous contents. Glycogen particles were also occasionally present inside vesicles or in the extracellular matrix. These may be associated with the exocytosis of glycosaminoglycan components into extracellular spaces and the formation of the stellate reticulum.

Animals↗
PubMed1998

An in vitro system for the analysis of changes in depth distribution of diffusates in bacterial films.

No suitable technique exists which allows simultaneous analysis of time- and depth-dependent concentrations of all components of interest in single samples of intercellular fluid from dental plaque biofilms. We have developed an in vitro model which allows detailed study of these interactions by analysis of intercellular fluid and pH measurement at the film base. Compact, defined-depth films of Streptococcus mutans were formed in a micrometer-controlled, variable-depth well and bathed in synthetic saliva. Films exposed to synthetic saliva containing glucose for 2 min followed by clearance with glucose-free synthetic saliva gave typical 'Stephan-type' pH profiles. Intercellular fluid isolated from successive 200-microm-thick sections of 600-microm-deep films was analysed by ion chromatography. A concentration gradient of lactate, falling with depth, was measured. The experimental system described here, the first of its type to be described, can easily be used to analyse pH changes and the depth-dependent distribution of diffusates in a model bacterial film. Although this bacterial film is far removed from a natural biofilm, the apparatus has potential for the study of grown biofilms and is an important advance towards position-dependence analysis of diffusates in biofilms.

Analysis of Variance↗
PubMed1983

An automatic electronic apparatus for generating and recording a ramp stimulus for analgesia testing.

Analgesia testing is conveniently done by applying an electrical stimulus to the tooth pulp of an animal that, in sufficient strength, causes an observable response. The difference in stimulus strength required in treated and control animals is an effective measure of analgesia, if the conditions can be sufficiently standardized. We describe an apparatus which generates a ramp stimulus at a controlled rate, allows accurate determinations of the response voltage with a digital readout, allows holding a reading to determine whether the response is a valid one, and automatically terminates the stimulus when the maximum voltage is reached. This apparatus was constructed from readily available components and can easily be modified to produce various ramp speeds, modulation frequencies, and maximum voltage outputs.

Analgesics↗
PubMed1999

Customized mold brachytherapy for oral carcinomas through use of high-dose-rate remote afterloading apparatus.

OBJECTIVE: The aim of this study was to investigate the role of the combined use of customized molds and recently available remote afterloading brachytherapy apparatus with more flexible catheters in the treatment of superficial oral carcinomas. STUDY DESIGN: Four patients with oral squamous cell carcinoma who were treated through use of this combined technique were analyzed retrospectively. The molds were made from transparent acrylic resin through use of a dental technique. The combined approach was applied as a boost therapy after external irradiation. RESULTS: The 4 patients had had no recurrence of tumor or radiation injury by the end of the follow-up period. CONCLUSIONS: The combined technique could be an excellent method of treating superficial carcinomas of the oral cavity.

Brachytherapy↗
PubMed2006

Collagen fiber architecture of the periodontal ligament in equine cheek teeth.

The objective of this study was to examine the spatial arrangement of the fiber apparatus of the equine periodontium which is supposed to meet two contrary requirements: (1) to attach the tooth firmly and elastically to the alveolar bone; and, to be appropriately remodeled and reconstructed in order to facilitate the prolonged eruption of the tooth. Specimens of periodontal ligament were obtained from the buccal and lingual/palatal aspects of the first molars from the maxilla and mandible of 12 horses. The animals were assigned to three age groups. Histological sections were prepared from three specific horizontal levels of the periodontal ligament and examined with conventional and polarized-light microscopy. At the gingival level, collagen fascicles (diameter > 200 microm) were densely packed. Their spatial alignment was the same in all age groups. The architecture of the collagen fiber apparatus differed at the middle and apical levels in the three age groups. There was a clear distinction between fibers, bundles, and fascicles. Bundling of collagen fibers, density of the fiber arrangement, and collagen fascicles with an alveolo-cemental orientation increased with age. The collagen fiber apparatus of the equine periodontal ligament is highly adaptive, responding continuously to the dynamic changes in the periodontal environment. Site-specific arrangements and age-dependent structural variations are assumed to maintain tooth support as the reserve crown gradually decreases in length with progressive dental attrition. Most of the age-dependent changes to the periodontal ligament in teeth examined in this study occurred at the apical level. The apical region of young teeth had no periodontal attachment, while the roots of older teeth were firmly attached to the alveolus. When evaluating periodontal ligament development, the individual tooth's 'dental age' should be considered rather than the animal's age to account for individual tooth eruption times.

Age Factors↗
PubMedDate not supplied

[Electrognathography and its application in dentistry].

The problem of spatial recording and analysing of mandibular movements was always of interest in dentistry. The permanent development of new technologies has resulted in a wide range of various methods and measuring systems for recording mandibular movements. However, only some of them have fulfilled a greater number of evaluation demands of modern measuring systems, which permit their industrial production. The paper discusses electrognathography as one of the most up-to-date methods widely used in the study of mandibular kinetics. The principles, performance and various possibilities of use of the two commercial electrognathographic apparatuses, now present on the world market, are presented. They are Sirognathograph (Siemens A.G., Bensheim, W. Germany) and Mandibular Kinesiograph (Myo-tronics Research, Seattle, U.S.A.)

Dental Occlusion↗
PubMed1976

[Ultrastructural study of human pulp cells cultured in vitro].

Primary cultures from human dental pulp were produced in Leighton tubes in the compound nutritive medium of Eagle consisting of calf serum, ascorbic acid, penicillin and streptomycin. After 2 months, the coverglasses supporting the cultures were recovered and fixed for electron microscopy. The results obtained showed a polarisation of the cells, the presence of a cilium, a highly developed endoplasmic reticulum, a typical Golgi apparatus with coated vesicles in the vicinity, elongated dense secretion vesicles containing a cross-striated filamentous material, numerous mitochondria, microfilaments with thickenings, microtubules, secretion granules, multivesicular bodies and electron dense structures united by a fibre with a periodic cross-striation of 640 A. These cells secreted a collagenous matrix uith an at random fibrillar distribution, fusiform outlines of fibrils (diameters varying from 650 A to 3,600 A), a cross-striation of 640 A and the presence of electron dense zones on the fibrils. "Globules" (with a trilamellar membrane of about 110 A) were identified in the extracellular medium. The possible comparisons between the typical characteristics of these cells and those of the odontoblast and pulpal fibroblasts were discussed.

Cell Nucleus↗
PubMed1991

Third molar eruption among rural Nigerians.

Times of eruption of third molars were studied in rural Nigerian adolescents--125 males and 133 females. Results of this study showed that the average age for the initial eruption of third molars was 15 years in male subjects and 13 years for female subjects. The incidence of eruption showed a steep rise after the age of 16 years for male subjects and 14 years for female subjects. By the age of 19 years, all third molars had erupted into the oral cavity. The eruption of lower third molars was generally ahead of the upper third molars for all age groups. The results of this study suggest that (1) the timing of third molar eruption is strongly influenced by the availability of mandibular trigone space, (2) the attrition and shrinkage of the dental arch, probably as the result of nonrefined highly fibrous diets, produce larger mandibular trigone spaces, and (3) the early eruption of third molars observed in the present study may be due to the nature of the diet used and the vigorous employment of the masticatory apparatus (from infancy) by the subjects examined.

Adolescent↗
PubMed1993

Structure of the bone interface to dental implants in vivo.

Dental implant materials can develop different kinds of interfaces when used for bone or tooth substitution. This paper describes the tissues and the tissue reactions of the interface created in the implantation bed between bone tissue and implants made of dense sintered hydroxylapatite. Healing was clinically and histologically evaluated during a six-month to five-year period. The light microscopic results show extensive bone apposition on the osseous sides of loaded implant cylinders and also on subperiosteally placed granules of dense hydroxylapatite. The presence of the loaded implant did not disturb the normal bone physiology. Bone turnover also included the bone tissue toward the implant surface. At the ultrastructural level, an amorphous collagen-free zone of about 200 nm was frequently observed which was separated from the surrounding mineralized extracellular matrix by a thin, electron-dense layer of about 20-100 A. Contact microradiographs showed an intimate bond to bone. The bone growth extending up the implant cylinder was always accompanied with an embedding of collagen fibers and the presence of a well-developed and complete new gingival attachment apparatus. This was confirmed by scanning electron microscopy. However, any inflammatory reactions in the transmucosal area were accompanied with concomitant bone resorption and loss of bone support.

Alveolar Process↗
PubMed1981

Ultrastructure of differentiating preameloblasts from tooth germs of the permanent dentition of Macaca mulatta and Macaca arctoides.

Cytodifferentiation of inner enamel epithelium and the adjacent connective tissue from the tip of the cervical loop to the initiation of enamel elaboration in two Macaca species was examined. Ten- to twelve-month-old specimens were fixed by perfusion and the permanent tooth buds were prepared for transmission electron microscopy. At the cervical loop proper, inner enamel epithelium cells have lobed nuclei, a paucity of cytoplasm, and wide extracellular spaces; the basal lamina facing the dental papilla is straight. With increasing distance from the tip of the cervical loop, the following changes occur gradually: (a) preameloblasts elongate from 15 to 45 micrometers, and their organelles, particularly mitochondria and profiles of rough endoplasmic reticulum, become more numerous; (b) extracellular spaces decrease between preameloblasts starting at the basal (infranuclear) end; (c) the basement membrane becomes convoluted and associated with aperiodic fibers; (d) preodontoblast projections penetrate the aperiodic fibers; (e) collagen fibers subjacent to the basement membrane increase in density, with particularly thick fibers paralleling the aperiodic fibers. These modifications occur within three-fourths of the distance from the tip of the cervical loop to the mineralization front. The condensation of preodontoblasts is followed immediately by predentin synthesis. Concomitantly, the basement membrane breaks down and the aperiodic fibers are engulfed by preameloblasts. Preameloblast projections penetrate junctional predentin, contact mineralized dentin, and enamel synthesis ensues. At this stage the ameloblast is 45 micrometers long, the nucleus is central or basal, the Golgi apparatus has migrated apically, but the Tomes' process has not yet formed. The results indicate that odontogenesis in Macaca monkeys more closely resembles human odontogenesis than does that in the murine rodents.

Ameloblasts↗
PubMedDate not supplied

Effect of cutting instruments on permeability and morphology of the dentin surface.

There are major differences in morphological detail after cutting the dentin surface among the methods commonly used to prepare dental cavities. The purpose of this study was to compare dentin permeability and the morphology of the dentin surfaces prepared with diamond and carbide steel burs after etching with 6% citric acid. Twenty-four freshly extracted human third molars were sectioned, mounted on plexiglass, and connected to the dentin-permeability measuring apparatus. The permeability of dentin was measured by fluid filtration and expressed as hydraulic conductance. There were two study groups of 12 teeth. Each tooth had one occlusal cavity preparation prepared but utilized three depths: the original was prepared just into the dentin, the second 0.5 mm deeper than the first, and the third 0.5 mm deeper than the second. One group had the first cavity prepared with a diamond, the second deepened using a steel bur, then the third depth was made by use of the diamond. The other group had the first cavity preparation prepared with a steel bur, deepened 0.5 mm again using a diamond, then deepened again using a steel bur. Dentin permeability was measured after cavity preparation, then after 2 minutes of acid etching. Analysis of variance and Duncan's multiple range test were used to establish whether differences were significant at the 0.05 confidence level. Prepared and acid-etched surfaces were characterized using a scanning electron microscope to identify any differences between the two groups. After acid etching with 6% citric acid, the permeability of dentin cavities prepared with diamond burs was significantly less than the permeability of cavities prepared with carbide steel burs. After etching, there were differences in the appearance of the dentin surfaces prepared with diamonds and steel burs. Dentin bonding agents may have their effectiveness reduced when placed following cavity preparation by use of a diamond.

Dental Bonding↗
PubMed1978

[Report on the capsule dosage and mixing system. 3. Suitability testing from a technological and clinical point of view].

The results from experiments with composite filling materials, silicate cements, stone cements, polyacrylate cements, EBA cements and amalgam testify to the suitability of a mixing apparatus already presented (cf. Par II). Apart from industrial predosed products, well known multicomponent materials prepared until now manually, among which Evicrol, were mixed mechanically.

Acrylates↗
PubMed1986

[Odontogenic myxoma. A histoenzymologic and ultrastructural study. Apropos of 5 cases].

The myxoma of the jaws represent 8% of the odontogenic tumours in our series (324 cases). The 5 cases described here were studied by histoenzymological and electron microscopic methods. The first method demonstrated in the majority of tumoral cells a high level of activity of alkaline phosphatases and ATPases similar to that noted in odontoblasts of the dental pulp. In addition, an acid phosphatase activity was also present in numerous cells but usually at a low intensity. Ultrastructurally, the tumour was composed of 3 main cellular types: young round cells with numerous ribosomes; stellate secretory cells with well-developed granular ergastoplasma and Golgi apparatus; fusiform cells with characteristics of fibroblasts. Some macrophages and myofibroblasts were also present. The intercellular substance was granulofilamentous and in one of our cases calcifications were obvious upon some collagen fibers. All these results seem to corroborate the hypothesis of odontogenic nature of the tumour. Early odontogenic induction induces the transformation of fibroblasts into cells with enzymatic activities similar to those of odontoblasts and the calcification of collagen fibers seen in one of our cases would express an early mineralization.

Esterases↗