Keratocystic odontogenic tumors have a high level of proliferative activity in epithelial cells and they tend to grow aggressively in the jaw. The tumor dramatically decreases in size by decompression of the intracystic fluid pressure. We herein focused on the roles of interleukin (IL)-1α and demonstrated the biochemical mechanisms of the tumor growth. We found that IL-1α is strongly expressed in the lining epithelial cells of the tumors, and the intracystic fluid levels of IL-1α are significantly higher than the levels of the other inflammatory cytokines of IL-6 and tumor necrosis factor-α (TNF-α). The expression of IL-1α in the epithelial cells decreases after the marsupialization of the tumor. In vitro experiments also reveal that positive pressure enhances the expression of IL-1α in the tumor epithelial cells in culture. IL-1α stimulates the production of matrix metalloproteinase (MMP)-9, and activates the released proMMP-9 by increasing the expression of proMMP-3 and plasminogen activator urokinase (u-PA) in the tumor epithelial cells. In the fibroblasts isolated from the tumors, IL-1α increases the expression of proMMP-1, proMMP-2, and proMMP-3. IL-1α also activates proMMP-2 by inducing the expression of membrane-type 1 matrix metalloproteinase (MT1-MMP) synergistically with type I collagen. Furthermore, IL-1α increases the expression of macrophage colony-stimulating factor (M-CSF) and cyclooxygenase (COX)-2 in the fibroblasts. The COX-2 synthesizes prostaglandin E₂ (PGE₂), and the secreted PGE₂ stimulates the expression of receptor activator of nuclear factor-κB ligand (RANKL), while neither IL-1α nor PGE₂ affects the expression of osteoprotegerin (OPG) in the fibroblasts. The fibroblasts express Ca²⁺-sensing receptor (CasR) on the cell surface, and extracellular Ca²⁺ activates COX-2 expression via the CasR. A strong relationship may thus be present between the intracystic fluid pressure and IL-1α expression in epithelial cells, and the released IL-1α may play a crucial role in the growth of keratocystic odontogenic tumors by stimulating proteolytic enzyme production and osteoclastogenesis.

A modification of the surgical technique for extracting impacted lower third molars is required to decrease the rate of complications including inferior alveolar nerve injury. In this study, a new two-stage extraction method for the horizontally impacted lower third molar was developed. During the first stage, only the crown was removed after separating the impacted tooth at the neck. Thereafter, the root(s) was pulled toward the anterior direction with an elastic band at 130-150 g over a 7-day period. Next, the root(s) was extracted. This method was firstly attempted for 20 horizontally impacted lower third molars, the roots of which had been close to the mandibular canal in panoramic radiographs and were pulled for 20.8 ± 11.5 (n = 20) days. The roots in 17 of 20 cases (85%) were loosened from the sockets and extracted easily without any complications. These outcomes suggest that this two-stage method is useful for the extraction of a horizontally impacted lower third molar in order to decrease the rate of inferior alveolar nerve injury.

In the present study, the effects of bulb type palatal lift prosthesis (bulb-PLP) therapy on nasality and velopharyngeal function (VPF) of patients with velopharyngeal incompetence (VPI) following palatoplasty were longitudinally assessed.The subjects included 18 patients (3 to 52 years of age) who had shown persistent VPI following palatoplasty and who had received bulb-PLP therapy. Nasality and VPF were assessed by perceptual voice analysis, nasometer test, blowing test, and cephalometric radiographic examination. Based on the outcomes of bulb-PLP therapy, the subjects were classified into two groups: the effective group and the ineffective group. Furthermore, the obturating and VPF-activating effects by bulb-PLP therapy were analyzed, and factors relating to different VPF activities were determined.All subjects achieved adequate VPF by wearing a bulb-PLP. After treatment, 10 patients (55.6%) achieved successful activation of VPF without bulb-PLP (the effective group), while persistent VPI remained in 8 patients (the ineffective group). The beginning-blowing ratio of the effective group was significantly greater than that of the ineffective group (P < 0.05) and the velopharyngeal distance (V-P distance) of the effective group tended to be smaller (P = 0.07). Regarding the shape of the bulb head, the angular type was dominant in the ineffective group, while the round type was dominant in the effective group.Bulb-PLP therapy was useful for providing adequate VPF activation. Possible signs of the subsequent effective activation of VPF are considered to be: 1) preexisting adequate VPF on blowing, 2) smaller V-P distance, and 3) synchronized palatopharyngeal movement.

BACKGROUND: Systemic and local factors may lead to disruption of craniofacial growth and development, causing an imbalance between the orofacial skeleton, muscle and soft tissue, dental occlusion, and the dental arch during growth periods. We aimed to reveal whether the prevalence of incompetent lip seal (ILS) varies with age and region, as well as to clarify the factors related to an ILS, in a national, large-scale epidemiological study. METHODS: We surveyed 3399 children, from 3 to 12 years of age, visiting 66 pediatric dental clinics throughout Japan. For this survey, we employed a questionnaire consisting of 44 questions regarding daily health conditions and lifestyle habits. We evaluated the differences in ILS prevalence by age and region (using a Cochran-Armitage test for trend and a Kruskal-Wallis test), and the relationship between ILS and factors investigated in the questionnaire (using Spearman's rank correlation coefficient). RESULTS: We observed that 30.7% of Japanese children exhibited an ILS and that the ILS rate increased with age (p < 0.001). There were no regional differences in the rate of ILS in Japanese children (p = 0.506). We revealed that 12 of 44 survey items exhibited a statistically significant correlation with ILS (p < 0.001), using Spearman's rank correlation coefficient. These items involved orofacial morphology, mouth breathing, and possibly, allergic rhinitis. CONCLUSION The rate of ILS seems to increase with age in children, throughout Japan. Therefore, this disorder may not self-correct during the growth periods in these children. Guidelines are required for pediatric dentists to recognize ILS among children aged 3-12 years.
Child ; Child, Preschool ; Cross-Sectional Studies ; Female ; Humans ; Japan/epidemiology* ; Lip/abnormalities* ; Male ; Prevalence