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PubMed1992

Radiofrequency gas plasma (glow discharge) disinfection of dental operative instruments, including handpieces.

The radiofrequency-stimulated argon gas plasma (glow discharge) technique, already well-known for surface cleaning and activation of adhesion, was investigated for determination of its separate potential for rapid disinfection of dental operative instruments. Disinfection effectiveness was judged from diminished post-treatment recovery of viable organisms from the instruments agitated in saline. Streptococcus salivarius, Bacillus stearothermophilus, and Escherichia coli were used as primary contaminant organisms, dried from gelatin-thickened laboratory cultures onto the instruments and not subjected to any preliminary cleaning steps. Significant disinfection was obtained, with no sensible temperature increases, in under 10 minutes in laboratory apparatus consuming fewer than 5 Watts of power per cycle. Also, clinically used and deliberately-saliva-contaminated high-speed handpieces were gas-discharge-treated, with their resultant rapid disinfection noted by complete suppression of the viability of any transferred natural contaminant organisms within two minutes. With regard to preservation of instrument quality, it was also shown that this low-temperature gas-discharge method provides the noted substantial disinfection without deterioration of sharp edges. Work now in progress suggests that the method can provide cool, rapid, and complete sterilization when hydrogen peroxide vapors are present in the gas plasma used for treatment of instruments first given the normally recommended thorough pre-cleaning.

Argon↗
PubMedDate not supplied

[A method for modernization of intraoral roengenography].

Experience in the use of PARDUS X-ray diagnostic apparatuses for intraoral roentgenography of maxillodental system is described. A method providing better uniformity of amplification in roentgenographic images of maxillodental system is suggested.

Equipment Design↗
PubMed1986

Resorption of the mouse incisor after the application of cold to the periodontal attachment apparatus.

In order to study in detail the processes leading to the resorption and ankylosis of teeth after trauma, the effects of cold application on the periodontal tissues were studied in the mouse. Liquid nitrogen was applied locally to the outer surface of the lower jaw which resulted in a freezing of the incisor and its surrounding tissues. The healing processes in the damaged periodontal ligament and the accompanying phenomena of ankylosis and dental root resorption were investigated histologically at both the light and electron microscopic levels. As a result of cold application, the cells in the periodontal ligament were killed. After a few days, the ligament started to be repopulated with cells like fibroblasts and macrophages. From 3 days on, mineral crystallites were deposited along the cementum covering the lingual, mesial, and lateral surfaces of the incisor, finally resulting in a 4-6 micron thick layer. During the period of 7-12 days following cold application, this layer of mineralized material started to be phagocytosed and degraded, presumably by mononuclear cells. Finally, extensive root resorption and some ankylosis between the tooth and the alveolar bone were observed. In the resorbed areas, cells were seen which could not be distinguished from osteoclasts. In some instances, their ruffled border was in close apposition with each of the three mineralized tissues--dentin, cementum, and alveolar bone. It is hypothesized that the deposition and subsequent phagocytosis of mineralized material along the root surface may be an important factor in the initiation of dental root resorption.

Animals↗
PubMed1975

Chronic myofascial pain-dysfunction syndrome with chest pain.

A patient with a myofascial pain-dysfunction (MPD) syndrome with pain radiating into the chest has been described. A direct relationship between a dental malocclusion and the chest pain was confirmed by tests. The patient was treated for MPD syndrome related to the malocclusion, and the chest pain symptoms were relieved. This report demonstrates the need for the dentist to consider not only the muscles of mastication in the management of problems of the neuromuscular apparatus but also the delicate balance which exists between the masticatory apparatus and the postural muscles of the head and neck.

Adult↗
PubMed1989

An investigation of possible iatrogenic damage caused by metal rubber dam clamps.

Rubber dam may be held in place over a tooth by metal clamps. It has been shown that a mismatch of contact between the clamp gripping edge and the tooth surface may be reduced to a point contact, thereby concentrating the gripping force generated by the bow of the clamp. Experiments were conducted to measure the force. Clinically realistic loading of the tooth surface by sections of the gripping edge of clamps was carried out using special apparatus. Examination by scanning electron microscopy showed that iatrogenic damage to the tooth could occur. Therefore a plea is made for clamps to be redesigned to reduce any harm.

Dental Instruments↗
PubMed2000

Influence of relative layer height and testing method on the failure mode and origin in a bilayered dental ceramic composite.

OBJECTIVES: The purpose of this study was to examine the influence of testing method (uniaxial and biaxial) and relative layer heights on the failure origin and failure mode of bilayered ceramic composite beams and disks composed of In-Ceram and Vitadur Alpha porcelain. METHODS: Beams and disks were fabricated, with relative layer heights of 1:2, 1:1, and 2:1, respectively, for In-Ceram and Vitadur Alpha porcelain. Ninety specimens each (thirty 1:2, thirty 1:1, and thirty 2:1) were tested in 3-point, 4-point-1/4-point, and biaxial ring-on-ring testing apparatuses. Fractography was used to categorize failure origins as either surface or interfacial, and failure modes as delamination or nondelamination. RESULTS: Surface and interfacial failure origins were observed in 3-point and biaxial disk test specimens, but not 4-point-1/4-point specimens where only surface failures occurred. None of the "clinically similar" specimens (1:2) failed at the interface. All testing methods resulted in delamination of Vitadur Alpha from the In-Ceram, while only 3-point and biaxial disk testing methods resulted in crack propagation through the composite interface without delamination. SIGNIFICANCE: Varying relative layer heights or varying testing method in laminate composite tensile specimens can affect failure mode and failure origin.

Adhesiveness↗
PubMed2006

Ultrastructural and immunocytochemical characterization of immortalized odontoblast MO6-G3.

AIM: To investigate an immortalized murine odontoblast cell line as a potential alternative for experimental studies on dentinogenesis. METHODOLOGY: The MO6-G3 cell line was investigated morphologically over 3, 7, 11 and 42 days of culture, using histochemical localization of dentine sialoprotein (DSP), alkaline phosphatase (AP), type I collagen and actin filaments, histoenzymatic staining and biochemical investigation of AP and finally, transmission and scanning electron microscopy. RESULTS: Scanning electron micrographs showed elongated cells. Accordingly, a polarized organization of odontoblasts was observed by transmission electron microscopy, identifying distinct subcellular compartments as described in vivo. The secretion apparatus, which includes cisternae of rough endoplasmic reticulum, Golgi apparatus saccules and secretion vesicles and granules, was longitudinally organized in the supranuclear compartment ending distally in the secretory pole. A cellular process was observed. The investigation of the cytoskeleton network revealed that actin microfilaments were organized in parallel stress fibre oriented depending on the longitudinal axis of the cytoplasm. Immunofluorescent labelling showed a continuous expression of type I collagen, DSP and AP. A unipolar distribution characterized intracellular DSP immunoreactivity. Histoenzymology revealed AP active sites increasing from 3 to 11 days albeit with a moderate level of activity comparatively to the in vivo situation in dental cells. CONCLUSION: This cell line MO6-G3 not only showed the criteria of odontoblast phenotype as previously reported but also the characteristic morphodifferentiation pattern of polarized odontoblasts at the cellular level but with an apparent random distribution.

Actin Cytoskeleton↗
PubMed1993

Periodontal health of the population in eastern Germany (former GDR).

The periodontal status of 1688 inhabitants of eastern Germany (former GDR) was investigated between July 1991 and March 1992, using the CPITN. The results show that only 1.4% of those examined have a healthy periodontal apparatus, whereas 40.1% had some signs of severe periodontitis (CPITN 4). This implies a very high therapy requirement in all age-groups, with 93.1% of 15- to 19-year-olds in need of peridontal treatment (CPITN 1 + 2 + 3 + 4). A comparison between educational qualifications and frequency of brushing or routine dental checks reveals a better level of prophylaxis in the more educated classes. As expected, the CPITN code with good oral hygiene and regular dental checks was significantly lower than with poor oral hygiene and infrequent dental checks. The high prevalence of periodontal disease lends urgency to the development of an extensive prevention concept introduced in childhood.

Adolescent↗
PubMed1979

Fine structural observations of calcium storage in human dental pulp cells in primary culture.

Primary culture of explants of human dental pulp tissue allows the study of the cytophysiology and differentiation of the cultured cells over a two-week period. The distribution of calcium was found in two different experimental conditions : with and without a calcium loading, by mean of a lead technique checked by microprobe analysis. The existence of two cell populations was revealed. Intra-mitochondrial ring-like granules characterize type 1 cells when overloaded, while a strong calcium storage is detected in the rough endoplasmic reticulum, Golgi apparatus and mitochondrial (without any inner organization of the deposits) of the type 2 cells. Our results also show the presence of calcium on gap-junctions (revealed) by lanthanum method), and on the extracellular matrix (collagen fibres and complex carbohydrates). The ability of some mitochondria to store calcium (ring-like granules) suggests that the type 1 cells are fully differentiated in odontoblast-like cells and perhaps engaged in mineralization processes. The calcium binding sites, localized on the extracellular matrix may therefore be considered as the earliest foci of calcification.

Calcium↗
PubMed1991

Establishment of acellular extrinsic fiber cementum on human teeth. A light- and electron-microscopic study.

The present study describes for the first time the development of early acellular extrinsic fiber cementum (AEFC) until its establishment on human teeth. Precisely selected premolars with roots developed to 50%-100% of their final length were prefixed in Karnovsky's fixative and most of them were decalcified in EDTA. Their roots were subdivided into about 10 blocks each, cut from the mesial and distal root surfaces. Following osmication, these blocks were embedded in Epon and sectioned for light- and transmission electron microscopy. Some blocks were cut non-demineralized. From semithin stained sections, the density of the collagenous fiber fringe protruding from the root surface was measured by using the Videoplan-system. After initiation of this fiber fringe and its attachment to the dentinal root surface followed by mineralization, the fringe gradually increased in length and subsequently became mineralized. Fringe elongation and the advancement of the mineralization front appeared to progress proportionally. Thus, in all stages of AEFC development, a short fiber fringe covered the mineralized AEFC. Its density remained constant, irrespective of AEFC thickness. The latter gradually increased and reached an early maximum of 15-20 microns in the cervical region. At this stage, the AEFC fringe appeared to fuse with the future dentogingival or other collagen fibers of the tooth supporting apparatus. Mineralization of the fringe commenced with isolated, spherical or globular centers, which later fused with the mineralization front and became incorporated in AEFC.

Adolescent↗
PubMed1992

Organic tooth wear--overlooked in anatomy texts.

Most anatomy texts depict gear-like apposition of adult upper and lower teeth. But this apposition generally does not occur in civilized man. On the contrary the widespread tooth attrition which occurs in primitive man, is well established. This attrition, which is not depicted in anatomy texts or correctly evaluated in medical and dental education, is a natural protective mechanism that functions to preserve, oral, pharyngeal, and respiratory physiology throughout life. As man removed grit, sand and other abrasive food from his diet, he deprived himself of a natural aid, i.e. attritional wear of teeth that protects the physiology of his mouth and the swallowing and respiratory apparatus (4). In contrast to this the unworn teeth, characteristic of present-day man, prevent anatomic and physiologic changes that normalize oral pathways. For these reasons, 'textbook' tooth occlusion should be re-evaluated.

Humans↗
PubMed1999

[Non-Hodgkin lymphoma of the maxilla. Report of a case].

Lymphomas are primitive neoplasias of the lympho-reticular system and are classified into two principal categories: Hodgkin's lymphoma (HL) and Non-Hodgkin's Lymphoma (NHL) each classified into low, medium and high grades, according to their clinical and cytological characteristics. The treatment and prognosis of such neoplasias vary according to the distribution of the illness and to the moment of initial diagnosis. In NHL, treatment depends prevalently on the histological subtype. Over the last few years it has been possible to associate to defined nosographic entities a characteristic phenotype, and to formulate a phenotypical classification of chronic lymphoproliferating illnesses. The classification of the Working Formulation subdivides lymphomas into groups of increasing malignancy. In histological sections, non-Hodgkins lymphomas are relatively homogeneous, uniformly cellular and dominated by malign lymphocytes. The symptomatology of NHL can vary according to the different location. The clinical manifestation of NHL can be in the form of swelling or ulceration. In contrast with lymphonodal lymphoma, in which the spread through blood to distant lymphonodal regions or extra lymphonodal areas is rapid, the extra lymphonodal ones show a clinical course of illness comparable with those of carcinomas. The authors present the case of a 89 year-old patient with an ulcerated, non painful swelling in the upper right alveolar maxillary region, showing slow development, soft consistency and indefinite edges; this lesion did not affected the normal physiological functions of the stomatognathic apparatus, thus explaining why the patient had noticed the appearance of the process two years prior to the visit but had not reported it. The pathological case-history shows traumas at the site of the lesions due to dentures. At the moment of the visit, the ortopathomographic examination of the upper and lower dental arch shows the presence of a lesion in the right maxillary region, radiographically opaque, with ill-defined margins and signs of continuity with the homolateral maxillary sinus.

Aged↗
PubMed2001

Tissue engineering's impact on dentistry.

Tissue engineering is a novel and exciting field that aims to re-create functional, healthy tissues and organs in order to replace diseased, dying, or dead tissues. The field has developed due to the inadequate supply of organs and tissues for patients requiring organ and tissue replacement. The following review first describes three major tissue engineering strategies. Although similar in their objectives, these strategies each maintain a unique component. Next, several examples of preclinical and clinical progress engineering oral-maxillofacial tissues are presented. Each of these examples highlights specific tissue engineering applications to different tissues of the oral-maxillofacial apparatus. Finally, practical implications are addressed as well as challenges that must be met in order for tissue engineering to reach its full potential.

Biocompatible Materials↗
PubMedDate not supplied

Metal allergy in dentistry: detection of allergen metals with X-ray fluorescence spectroscope and its application toward allergen elimination.

Numerous metal allergies possibly resulting from intraoral metal restorations have been reported, although the mechanism of onset is not yet completely understood. Allergen elimination may be the most effective treatment, and location of allergen metal becomes essential. The x-ray fluorescence spectroscope was used to detect the allergen metals in intraoral metal restorations and personal and household items of metal allergy patients. The apparatus was evaluated preceding its clinical application, and restorations and personal items for 381 patients were analyzed to detect allergens. Successful diagnoses and allergen elimination treatment of three patients are reported.

Adult↗
PubMed1990

Application of a new mechanical properties microprobe to study hardness of eroded bovine enamel in vitro.

A mechanical properties microprobe technique was used to study bovine tooth specimens that had been immersed in 50 ml of either cola beverage or sports drink for 1 min, 5 min, and 15 min. A Vickers diamond was used to analyze the test and control surfaces at 7V input. This corresponds to a 100 g load of a conventional indentation microhardness apparatus which was used for comparison. The results showed good agreement between the conventional and the microprobe hardness analyses. Enamel softening was found to be significant after 5 min immersion in both acidic drinks, while 1 min immersion did not cause softening. This shows that shorter immersion times than previously used can be applied in dental erosion studies in vitro. Compared with the conventional indentation microhardness measurements, however, the microprobe technique did not offer any advantage, such as assessment of the microelastic properties of enamel, probably because the biologic tissue did not allow reliable data collection during the loading and unloading phases of the instrument.

Animals↗
PubMed1999

Comparison of two devices for root canal cleansing by the noninstrumentation technology.

Optimal cleansing of the root canal system is a prime prerequisite for long-term success in endodontics. Recently, a new method and device were presented providing "automatic" root canal cleansing without the need of endodontic instrumentation. Cleanliness results equivalent to or better than those with conventional methods were achieved in considerably less time. The purpose of the present study was 2-fold: (a) optimization of the device to make it applicable to patients and (b) to measure its effectiveness against the predecessor model. A total of 156 root canals of 66 freshly extracted vital human molars were cleansed with the new device and their cleanliness compared with that of 149 canals of 52 molars cleansed previously with the first apparatus. Data indicated that the smaller new machine produced equivalent or better cleanliness results in the root canal system using significantly less irrigant (NaOCl).

Analysis of Variance↗
PubMedDate not supplied

An in vitro investigation of a comparison of bond strengths of composite to etched and air-abraded human enamel surfaces.

PURPOSE: The purposes of the study were to measure the tensile bond strength of composite resin to human enamel specimens that had been either etched or air-abraded, and to compare the quality of the marginal seal, through the assessment of microleakage, of composite resin to human enamel specimens that had been either etched or air-abraded. MATERIALS AND METHODS: Thirty mandibular molar teeth were decoronated and sectioned mesio-distally to produce six groups, each containing ten specimens that were embedded in acrylic resin using a jig. In each of the four treatment groups, the specimen surfaces were treated by either abrasion with 27 or 50 microm alumina at 4 mm or 20 mm distance, and a composite resin was bonded to the treated surfaces in a standardized manner. In the two control groups the specimens were treated with 15 seconds exposure to 36% phosphoric acid gel and then similarly treated before being stored in sterile water for 1 week. All specimens were then subjected to tensile bond strength testing at either 1 or 5 mm/min crosshead speed. For the microleakage study, the degree of dye penetration was measured 32 times for each treatment group, using a neutral methylene blue dye at the interface between composite and either 27 or 50 microm air-abraded tooth structure or etched enamel surfaces. RESULTS: The mean bond strength values recorded for Group 1 (phosphoric acid etch, 5 mm/min crosshead speed) was 25.4 MPa; Group 2 (phosphoric acid etch, 1 mm/min), 22.2 MPa; Group 3 (27 microm alumina at 4 mm distance), 16.8 MPa; Group 4 (50 microm alumina at 4 mm distance), 16.9 MPa; Group 5 (27 microm alumina at 20 mm distance), 4.2 MPa; and for Group 6 (50 microm alumina at 20 mm distance) 3.4 MPa. An analysis of variance (ANOVA) demonstrated significant differences among the groups, and a multiple comparison test (Tukey) demonstrated that conventionally etched specimens had a greater bond strength than air-abraded specimen groups. No significant difference in dye penetration could be demonstrated among the groups (p= 0.58). CONCLUSIONS: Composite resin applied to enamel surfaces prepared using an acid etch procedure exhibited higher bond strengths than those prepared with air abrasion technology. The abrasion particle size did not affect the bond strength produced, but the latter was adversely affected by the distance of the air abrasion nozzle from the enamel surface. The crosshead speed of the bond testing apparatus had no effect on the bond strengths recorded. The marginal seal of composite to prepared enamel was unaffected by the method of enamel preparation.

Acid Etching, Dental↗