The purpose of this study was to analyse the traumatic dental injuries (TDI) of Korean preschoolers by investigating the occurrence, type, area, cause, injured region, seasonal variation and the interval between injury and treatment. In this study, data from 1856 preschoolers aged 4 months to 6 years and 11 months (mean age : 3.6 +/- 1.6) were used, out of a total of 2761 patients who attended the Department of Pediatric Dentistry, Kyung Hee Dental Hospital for TDI between January 1998 and December 2007. All the data were statistically analysed using the anova and chi-square statics. Most of the patients were 1-2, 2-3 years old (24.5%, 25.4%) and boys were 1.67 times more likely to have TDI. The most common cause, location and seasonal variation of the trauma, were respectively falling (50.8%), at home (48.8%) and late spring. The treatment intervals usually occurred within a day. Most of the injuries involved single (47%) or double (38%) tooth/teeth. However, car accidents or sports trauma often involved multiple teeth. In both primary and permanent dentition, the most common teeth injured were maxillary central incisors (72.6%), and periodontal injury was caused by subluxation or concussion. Among the various types of hard tissue injuries, enamel fracture in the primary dentition (35.0%) and enamel-dentin fracture in the permanent dentition (45.8%) were the most common types.
The attachment, growth behaviour and the genetic effect of human gingival fibroblasts (HGF) cultured on titanium and different zirconia surfaces were investigated. HGF cells were cultured on (1) titanium discs with a machined surface, (2) yttrium-stabilized tetragonal zirconia polycrystals (Y-TZP) with a smooth surface and (3) Y-TZP with 100 microm grooves. The cell proliferation activity was evaluated through a MTT assay at 24 h and 48 h, and the cell morphology was examined by SEM. The mRNA expression of integrin-beta1, type I and III collagen, laminin and fibronectin in HGF were evaluated by RT-PCR after 24 h. From the MTT assay, the mean optical density values for the titanium and grooved zirconia surfaces after 48 h of HGF adhesion were greater than the values obtained for the smooth zirconia surfaces. SEM images showed that more cells were attached to the grooves, and the cells appeared to follow the direction of the grooves. The results of RT-PCR suggest that all groups showed comparable fibroblast-specific gene expression. A zirconia ceramic surface with grooves showed biological responses that were comparable to those obtained with HGF on a titanium surface.
PURPOSE
The accuracy of denture bases was compared among injection molding, milling, and rapid prototyping (RP) fabricating method.
MATERIALS AND METHODS
The maxillary edentulous master cast was fabricated and round shaped four notches were formed. The cast was duplicated to ten casts and scanned. In the injection molding method, designed denture bases were milled from a wax block and fabricated using SR Ivocap injection system. Denture bases were milled from a pre-polymerized block in the milling method. In the RP method, denture bases were printed and post-cured. The intaglio surface of the base was scanned and surface matching software was used to measure inaccuracy. Measurements were performed between four notches and two points in the mid-palatal suture to evaluate inaccuracy. The palatine rugae resolution was evaluated. One-way analysis of variance was used for statistical analysis at α=.05.
RESULTS
No statistically significant differences in distances among four notches (
P
>.05). The accuracy of the injection molding method was lower than those of the other methods in two points of the mid-palatal suture significantly (
P
<.05). The degree of palatine rugae resolution was significantly higher in the injection molding method than that in other methods (
P
<.05).
CONCLUSION
The overall accuracy of the denture base is higher in milling and RP method than the injection molding method. The degree of fine reproducibility is higher in the injection molding method than the milling or RP method.
It may be concluded that the modSLA surface promotes osteogenic effect and prevents osteoclastic differentiation. Promotion of osteoblastic proliferation after a short-term cell culture might be responsible for stimulated bone regeneration implying that early loading may be possible. Also, the anti-osteoclastic effect of the modSLA surface may contribute to maintenance of the marginal bone level of dental implants, implying long-term stability would be provided by this surface technology. The modSLA surface may not only make early loading possible but possibly reduce marginal bone loss during the maintenance phase.
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