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Objectives:To clarify the associations among tongue volume, hyoid position, airway volume and maxillofacial form using cone beam computed tomography (CBCT) data for children with Class-I, Class-II and Class-III malocclusion. Setting and SamplePopulation: Sixty children (mean age, 9.2 years) divided into Class-I, Class-II and Class-III malocclusion groups according to the A-nasion-B angle. Material and Methods: Cone beam computed tomography was used for threedimensional reconstruction of the maxillofacial region and airway. The hyoid position and the tongue, airway and oral cavity volumes were evaluated. Upper airway ventilation status was calculated using computational fluid dynamics. The groups were compared using analysis of variance and Kruskal-Wallis tests; relationships among the parameters were assessed using Pearson's and Spearman's rank correlation tests. Results:The tongue volume was larger in Class-III patients (50.63 cm 3 ) than in Class-I patients (44.24 cm 3 ; P < 0.05). The hyoid position was lower (49.44 cm), and anatomical balance (AB; tongue volume/oral cavity volume; 85.06%) was greater in Class-II patients than in Class-I patients (46.06 cm, 80.57%, respectively; P < 0.05 for both).The hyoid height showed a positive correlation with AB (r = 0.614; P < 0.001). Conclusions:Children with Class-III malocclusion have large tongue volumes and small AB; the reverse is true for children with Class-II malocclusion. The hyoid position is closely associated with AB in children with malocclusion.

The craniofacial morphology of children with unilateral cleft lip and palate (UCLP) differs from that of children without clefts. 1 Maxillary arch constriction is frequently observed in operated patients with UCLP. 2 Therefore, rapid maxillary expansion (RME) is often required in children with UCLP; in children without clefts, improvements in nasal airway ventilation and dentition expansion may be required. 3 However, improvements in nasal airway ventilation associated with RME in children with UCLP are unclear, particularly in cases involving nasal airway ventilation obstruction. 4 In studies investigating RME in patients with UCLP, the volume 5 and cross-sectional area 6 of the nasal airway reportedly increase. However, nasal septum deviation and the other nasal airway forms are often associated with abnormalities in patients with UCLP. 7 Therefore, it has been unclear whether expansion of nasal Objectives: Rapid maxillary expansion (RME) improves nasal airway ventilation in non-cleft palate children. Children with unilateral cleft lip and palate (UCLP) may have nasal obstruction and experience an increased risk of obstructive sleep apnoea. The effect of RME in UCLP children is unclear. This retrospective study evaluated RMEinduced changes in ventilation parameters in children with UCLP using computational fluid dynamics. Setting and Sample Population: Nineteen patients (10 boys, mean age 10.7 years)who required RME had cone-beam computed tomography images taken before and after RME. Twenty control participants (11 boys, mean age 11.1 years) received regular orthodontic treatment.Methods: Nasal airway ventilation parameters (air pressure, air velocity and airflow rate) were analysed via computational fluid dynamics, and nasal cross-sectional area (CSA) was measured.Results: Maximum pressure, velocity and nasal resistance were significantly reduced by RME in the UCLP group. Air flow rate and CSA on the cleft side significantly were increased by RME in the UCLP group. Conclusions:In children with UCLP, increasing the quantity of airflow and CSA on the cleft side by RME substantially improved nasal ventilation. K E Y W O R D S children, computational fluid dynamics, nasal airway, rapid maxillary expansion, unilateral cleft lip and palate 202 | IWASAKI et Al.width diameter and dentition improves nasal airway ventilation.Recently, computational fluid dynamics (CFD) has been used for evaluation of airway ventilation. 8 Regardless of upper airway shape, CFD reproduces the flow of air and can evaluate air current in the nasal airway alone. Therefore, we speculated that CFD evaluation may be more precise in the evaluation of complicated nasal airways in children with UCLP.The current study investigated improvements in nasal airway ventilation associated with RME in patients with UCLP via CFD in which nasal airway ventilation could be evaluated without being influenced by the complexity of nasal airway shape.

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Streptococcus mutans is a major cause of tooth decay due to its promotion of biofilm formation and acid production. Several plant extracts have been reported to have multiple biological activities such as anti-inflammation and antibacterial effects. This study investigated the antibacterial activity of three plant extracts, phellodendron bark (PB), yucca, and black ginger, and found that PB had a stronger effect than the other extracts. Then, the minimum inhibitory concentration (MIC) of PB against 100 S. mutans strains was investigated. The MIC range of PB was 9.8-312.5 µg/mL. PB suppressed the growth kinetics of S. mutans in a dose-dependent manner, even at sub-MICs of PB. Then, we investigated the effect of PB on S. mutans virulence. The PB suppressed biofilm formation at high concentrations, although PB did not affect the expression of glucosyltransferase genes. Additionally, PB suppressed the decrease in pH from adding an excess of glucose. The expression of genes responsible for acid production was increased by the addition of excess glucose without PB, whereas their expression levels were not increased in the presence of 1× and 2× MIC of PB. Although PB showed a bacteriostatic effect on planktonic S. mutans cells, it was found that more than 2× MIC of PB showed a partial bactericidal effect on biofilm cells. In conclusion, PB not only showed antibacterial activity against S. mutans but also decreased the cariogenic activity in S. mutans. K E Y W O R D Santibacterial agents and chemotherapy, bacteriology, pathogenesis, Streptococcus mutans