ABSTRACT
As a consequence of traumatic and toxic injury of the inferior alveolar and the mental nerves, disturbances of sensibility may develop during and after root canal treatment. Several reasons are possible. In most cases, however, such disturbances are the result of root canal filling materials that have been pressed into the mandibular canal. Based on all cases reported in the literature, this review summarizes and discusses symptoms, therapy, prognosis and prophylaxis of such sensibility changes following endodontic overfilling into the mandibular canal.
Subject(s)
Mandibular Nerve/drug effects , Root Canal Filling Materials/adverse effects , Cranial Nerve Diseases/chemically induced , Cranial Nerve Diseases/epidemiology , Cranial Nerve Diseases/therapy , Forensic Dentistry , Humans , Incidence , Prognosis , Root Canal Obturation/adverse effects , Sensation Disorders/chemically induced , Sensation Disorders/epidemiology , Sensation Disorders/therapyABSTRACT
Scanning electron microscopic study of bristle heads of 8 toothbrush brands commercially available in the Federal Republic of Germany and Switzerland has shown qualitative variations in the rounding of bristle ends. The percentage of acceptable end rounding of the bristles was for 4 brands above 75% and for 2 brands 55-56%. For 2 products, the percentage was below 40%. The new method of welding bristle bundles at their base into the head of the toothbrush was used only by one producer.
Subject(s)
Toothbrushing/instrumentation , Adult , Equipment Design , Evaluation Studies as Topic , Humans , Microscopy, Electron, Scanning , Toothbrushing/standardsABSTRACT
The altered structure of "Turner-teeth" was examined under the scanning electron microscope. The enamel surface revealed developmental disorders such as bowl-shaped pits, Tomes' process pits and enamel craters with rounded borders. On the fractured surfaces of yellowish discolored enamel, localized islands of pathological enamel were found. The enamel rods were atypically arranged and poorly mineralized. Surprisingly the prisms formed later by the same ameloblast often exhibited a entirely normal structure.
Subject(s)
Dental Enamel/ultrastructure , Tooth Germ/injuries , Child , Child, Preschool , Dental Enamel/pathology , Humans , Microscopy, Electron, ScanningABSTRACT
In this study the ultrastructure of exposed cementum just below the cemento-enamel junction was investigated. In a surface layer of exposed cementum measuring up to 4 microns in depth, newly formed crystallites were observed. These crystallites were 660-1800 A long and 130-260 A thick. They were thicker than those in the deeper zones of exposed cementum and in sound cementum. Electron diffraction studies showed that these crystallites were hydroxylapatite. In the zone of new crystallites at the tooth surface the crossbanding of collagen fibers was not discernible. At the tooth surface carious changes were seen only in minor areas. Another finding was the formation of large crystallites. They were found to have the following dimensions: length 3000 A, thickness 550 A.
Subject(s)
Dental Cementum/ultrastructure , Adolescent , Adult , Crystallization , Dental Cementum/analysis , Humans , Hydroxyapatites/analysis , Microscopy, Electron , Middle Aged , Surface Properties , X-Ray DiffractionABSTRACT
This scanning electron microscopic study of eight toothbrushes for children has shown differences in quality and quantity of the rounding of bristle ends. While four products which were examined for the first time were partially deficient, the preparation of the other toothbrushes had clearly improved in comparison to previous products. Quotas of acceptable end rounding of the bristles varied considerably between 14.3% and 90.2%. Welding of bristle bundles at their base into the head of the toothbrush offers hygienic advantages.
Subject(s)
Toothbrushing/instrumentation , Child , Equipment Design , Humans , Microscopy, Electron, Scanning , Quality Control , Toothbrushing/standardsABSTRACT
An electron microscopic investigation was undertaken to study a method for contrasting predentine collagen fibrils by their cross-striations after exposure of tissue to chromium solution for various periods. After 1 day of treatment, the cross-striations of collagen fibrils in predentine were clearly visible. The contrast of the cross-striations increased with longer periods of exposure to chromium. This method makes it possible to study the orientation of crystallites as well as collagen fibrils.
