Odontogenic calci®ed masses were present in the opercula of lower ®rst molars that were delayed in eruption. The masses were relatively small, opaque, white in color with a smooth texture. Histopathological examinations revealed that they contained osteodentin, cementum, and pulp-like components; however, not odontogenic epithelial cells or enameloid. Further, mesenchymal multinucleated giant cells and dysplastic dental matrices were observed in the connective tissues surrounding the masses. These clinical and histopathological ®ndings disagree with the features of pericoronal odontogenic hamartoma lesions, including odontoma, ameloblastic ®broma, and ameloblastic ®bro-odontoma. Therefore, we propose to categorize this odontogenic mass as a new variety of hamartoma, eruption mesenchymal calci®ed hamartoma.A 5-year, 10-month-old girl was referred to Osaka University Dental Hospital with the chief complaint of severe dental caries.Her medical history was unremarkable and there was no history of oral trauma. At the ®rst visit, both lower permanent ®rst molars were absent in her oral cavity, and radiographic examinations revealed a faint radiopacity above each lower ®rst molar ( Fig. 1a,b). At the age of 6 years 4 months, both the lower ®rst molars had not yet erupted and gingival hypertrophy was observed in the region (Fig. 2a). As the ®rst molars had reached the level of the occlusal surfaces of the proximal second primary molars in a radiographic examination, fenestration was performed in order to allow them to erupt. When we removed the opercula, calci®ed masses were found attached to the surrounding soft tissues on the occlusal surfaces of both ®rst molars (Fig. 2b,c). These masses were opaque and white in color with 246
Tooth brushing is accepted as an most effective measure to removal of supragingival plaque. The purpose of this study was to examine the effectiveness of a newly designed toothbrush both in brushing-simulator in vitro and in children. The newly designed toothbrush had an oval head with 8 tufts in 3 rows and cleaned the tooth surfaces of primary molar on the plastic model of the dentition more effectively in a brushing-simulator than the control toothbrush with 17 tufts in 3 rows. A total of 66 children participated the study to examine the effectiveness of the brush. The newly designed brush could remove the plaque more effectively from the primary tooth surfaces, especially upper buccal and lower lingual surfaces, than the control brush did. These results indicate that the newly designed toothbrush can remove supragingival plaque effectively in children. children. The purpose of the present study was to examine the effectiveness of this newly designed toothbrush in the dental plaque removal in children. Materials and methods Toothbrushes A toothbrush was newly designed to improve its brushing efficiency. The brush has an overall length of 135 mm and an oval head 2.21ן5.6( mm) with 8 tufts in 3 rows with serrated trim of end-rounded nylon bristles (Fig. 1a). A tuft was composed of 94 bristles and planted in the rectangular holes (Fig. 1b). The diameter of each bristle was 0.178 mm, and the maximum trim height 7.0 mm. A conventional manual toothbrush was used as a control. The control toothbrush has an overall length of 139 mm and a long oval head 5.41ן5.6( mm) with 17 tufts in 3 rows with straight trim of end-rounded nylon bristles (Fig. 1c). A tuft was composed of 60 bristles and planted in the round holes (Fig. 1d). The diameter of each bristle was 0.178 mm and the trim height 7.0 mm.
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