Mineralized bacillus-shaped deposits showing numerous bacterial molds on the surfaces were found in deep subgingival calculus with scanning electron microscopy, after the fractured surfaces were treated with NaOCl. Such structures may be derived from filamentous microorganisms attached with a large number of rod-shaped bacteria showing a 'bristle-brush' arrangement in subgingival plaque; namely, the filaments mineralized intracellularly, while the unmineralized rods dissolved with NaOCl treatment.
By using scanning electron microscopy, the successional transformation of plate-shaped octacalcium phosphate (OCP) to hexahedral whitlockite (WH) was observed in human dental calculus. Such a transformation indicates that some of the WH crystals are epitaxially formed on OCP crystals.
This study was undertaken to establish a method for evaluating speech disorders by determining the constancy of articulatory activity during the repeated pronunciation of plosives. Tested and compared were the speech patterns of 10 normal controls and one cleft palate patient tested at different stages, i.e., before prosthetic treatment (stage A), while wearing a temporary overdenture (stage B), at insertion of the final prosthesis (stage C), and at six months after insertion of the final prosthesis (stage D). All tested subjects were instructed to repeatedly pronounce /pa/, /ta/, /ka/ and /pataka/ as rapidly as possible until running out of breath. These vocal patterns then were analyzed by a sound spectrograph (DSP Sona-Graph, Model 5500, Kay Co. USA) and studied on an expanded time-wave CRT display to measure three items : the characteristics of the spectrographic pattern, the number of the repetitions, and the duration of the sound. The duration of the consonants and vowels were measured, as well as the intervals between each syllable. Further, each consonant was divided into two parts : the duration of the plosive spike, and the damping of this spike to the beginning of the next sound. Results revealed that the sound patterns of the cleft palate subject during stage A varied greatly from those of the normal subjects, but that these differences gradually diminished during stages B and C and became remarkably similar at stage D, almost resembling the patterns of the normal controls. While the number of repetitions that the cleft palate patient was capable of was limited during stage A, the ability to repeat plosives increased as the prosthetic treatment progressed. Sim-ilarly, the duration of the consonant and the plosive spike of the /k/ of the patient at stage A was much longer than that of the controls, but this difference also decreased. Based on the results of this study, it was concluded that to improve the speaking capability of cleft palate patients, the designed dental prosthesis must not only achieve naso-pharyngeal or naso-oral closure but also must include a compatible occlusal vertical dimension and a proper maxillary dental arch.
A rare case of central neurilemmoma arising in the mandible is reported. The tumor revealed unusual rapid growth in 2 years. To obtain pathological diagnosis of this tumor, an immunohistochemical technique using antibodies against myelin basic protein and S-100 protein was applied to the biopsy specimen. The immunohistochemical examination revealed the overgrowth of nerve sheath cells. The macroscopic and histological examination of the surgical material confirmed that the tumor was a neurilemmoma. In this report we discuss the usefulness of the immunohistochemical examination in diagnosing neurogenic tumor in a biopsy specimen.