Epithelial-specific requirement of FGFR2 signaling during tooth and palate development.

Reciprocal interactions between epithelium and mesenchyme are crucial for embryonic development. Fibroblast growth factors (FGFs) are a growth factor family that play an important role in epithelial-mesenchymal tissue interaction. We have generated epithelial-specific conditional knockout mice targeting Fibroblast growth factor receptor 2 (Fgfr2) to investigate the function of FGF signaling during craniofacial development. K14-Cre;Fgfr2(fl/fl) mice have skin defects, retarded tooth formation, and cleft palate. During the formation of the tooth primordium and palatal processes, cell proliferation in the epithelial cells of K14-Cre;Fgfr2(fl/fl) mice is reduced. Thus, FGF signaling via FGFR2 in the epithelium is crucial for cell proliferation activity during tooth and palate development.

The detection of Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans in the supragingival plaque of children with and without caries.

PURPOSE: The present study was undertaken to determine the presence of 3 periodontopathic bacteria in the supragingival plaques of 3- to 16-year-old children with different oral health conditions. METHODS: DMFT and dft, PMA index (P=papillary gingivitis, M=marginal gingivitis, and A=attached gingivitis), OHI (oral hygiene index), and oral malodor of each subject were determined prior to the collection of supragingival plaques. Periodontopathic bacteria (P. gingivalis, P. intermedia, and A. actinomycetemcomitans) in supragingival plaques were detected using an immunoslot blot assay with monoclonal 3 periodontopathic bacteria in the 2 subject groups (children with and without caries). P. gingivalis-positive subjects, but not their P. intermedia or A. actinomycetemcomitans counterparts, were correlated to oral malodor. Oral malodor was also correlated to debris index, a component of OHI. RESULTS: The group with the higher OHI showed a higher prevalence of periodontopathic bacteria. For the 3 periodontopathic bacteria in the subjects tested, P. gingivalis-, P. intermedia-, and A. actinomycetemcomitans-positive plaques were not age related. CONCLUSIONS: The supragingival plaques in children can harbor periodontopathic bacteria such as P. gingivalis, P. intermedia, and A. actinomycetemcomitans.

Basic study on vibrations during tooth preparations caused by high-speed drilling and Er:YAG laser irradiation.

BACKGROUND AND OBJECTIVES: An Er:YAG laser effectively removes dental hard substance, and causes less pain during tooth preparations than high-speed drilling. This laser was introduced to eliminate the noise, vibration, pressure, and heat associated with the high-speed drilling. However, the difference in tooth vibration caused by the Er:YAG laser and the high-speed drill is unclear. Therefore, the aim of this study was to evaluate tooth vibration obtained with the Er:YAG laser and high-speed drill. STUDY DESIGN/MATERIALS AND METHODS: Each of the five extracted permanent upper first premolars were built up in a plaster box. In this study, a silicone impression material was selected to simulate periodontal tissue. The vibration speed was measured by using a laser Doppler vibrometer. RESULTS: The Er:YAG laser irradiation energy was 50, 100, 145, 199, 300, and 350 mJ. As irradiation energy increased, vibration of the tooth also rose; a high-correlation coefficient was observed between them. We found that only a small amount of the tooth vibration occurred with the Er:YAG laser preparations. The mean vibration speed and standard deviation with the laser were 166 +/- 28 microm/second when the output energy was 145 mJ, whereas those with the high-speed drill were 65 +/- 48 mm/second. The frequency characteristic approached 230 Hz and 5 kHz, respectively. CONCLUSIONS: These results show that the high-speed drilling causes greater tooth vibration and has a frequency spectrum near the high sensitivity of hearing compared to the Er:YAG laser. This suggests a potential factor in provoking pain and displeasure during tooth preparation. Future study to examine the relationship of pain and amount of tooth vibration will be planned.