KJC Korea
Journal Central

The aim of this study was to evaluate the compomer cement and resin cement as an orthodontic band cement on zirconia crown. A total of 30 specimens were prepared. Preformed stainless steel crowns and zirconia crowns of upper right second primary molar were used. Orthodontic bands were cemented on stainless steel crowns (Group Ⅰ, n = 10) and zirconia crowns (Group Ⅱ, n = 10) with compomer cement. The other bands were cemented on zirconia crowns with resin cement (Group Ⅲ, n = 10). The tensile loads were applied to band to measure the bond strength. The mean of bond strengths of group Ⅰ, Ⅱ and Ⅲ were 0.79 MPa, 1.09 MPa and 1.56 MPa respectively. Bond strength of group Ⅱ is significantly higher than group Ⅰ. There was no significant difference between group Ⅱ and Ⅲ. Compomer cement and resin cement containing functional monomers showed favorable bond strength of orthodontic bands.

The aim of this study was to investigate the susceptibility of Mutans streptococci in both planktonic and biofilm states to erythrosine. S. mutans was cultured in brain-heart infusion (BHI) broth. Erythrosine was diluted in BHI broth and prepared at a concentration range of 0.02 - 10000 μg/L. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were measured using the microdilution method. After forming biofilms on 96-well plates, the minimum biofilm inhibitory concentration (MBIC) and minimum biofilm eradication concentration (MBEC) were measured. S. mutans was susceptible to erythrosine in both planktonic and biofilm states. MIC and MBC values were both 19.5 μg/L for the planktonic state, while MBIC and MBEC values were 313 μg/L and 2500 μg/L, respectively, for the biofilm state. Erythrosine (19.5 μg/L) exhibited a bactericidal effect on S. mutans (killing 99.9%) in the planktonic state. For biofilms, erythrosine inhibited biofilm growth and eradicated 99.9% of biofilm bacteria at higher concentrations than MIC and MBC. These MBIC and MBEC concentrations are much lower than known noxious doses, and the MIC, MBC, and MBIC values were even lower than clinical concentrations.

This study aimed to analyze the association of midpalatal suture (MPS) maturation stages with skeletal maturation and age and to obtain references for establishing a treatment plan for rapid maxillary expansion (RME). Cone-Beam Computed Tomography (CBCT) images from 480 children (240 boys, 240 girls) aged 7 - 15 years were obtained. MPS maturation stages and cervical vertebral maturation indicator (CVMI) were evaluated, and the correlations between MPS maturation stages, CVMI, and age were determined using the Spearman’s correlation test. The positive likelihood ratio (LHR) of CVMI for MPS maturation stages was calculated. MPS maturation stages and CVMI showed a strong correlation. Especially, CVMI 1 - 3 showed positive LHR greater than 10 for the diagnosis of stages A - C. MPS maturation stages and age were correlated strongly in girls and moderately in boys. Conventional RME produces the most favorable skeletal effect at CVMI 1 - 3 or those up to 12 years of age and fewer skeletal effects at CVMI 4 or at 13 years of age in girls and 13 - 15 years in boys. It is recommended to evaluate MPS maturation stages using CBCT before RME application at CVMI 5, 6 or at 14, 15 years of age in girls.

This study aimed to evaluate skeletodental characteristics of patient with maxillary lateral incisor agenesis (MLIA) in mixed dentition. It involved the children in early mixed dentition who visited Pusan National University dental hospital for orthodontic purposed and had intact primary canines. 38 children with MLIA and 38 controls with the same chronological age satisfying the inclusion criteria were selected. The craniofacial structures and dental arch dimensions of the MLIA were evaluated using model & cephalometric analysis and compared to controls. The rate of unilateral MLIA was high in male and the rate of bilateral MLIA was high in female. In model analysis, the width / length ratio of maxillary anterior portion of the MLIA group were higher and arch perimeter of the maxilla of the MLIA group were smaller than those of the control group (p = 0.003, 0.04). Cephalometric analysis showed that there were no significant differences in terms of skeletal, dental analysis. In soft tissue profile, nasolabial angle was larger in MLIAs than in controls (p = 0.039). Considering these skeletodental characteristics of MLIA, early diagnosis and proper management is highly recommended to minimize the possibility of functional defect.

The purpose of this study was to compare the bond strength of resin-modified glass ionomer (RMGI) to dentin with saliva contamination at different stages and using different decontamination procedures. Extracted human permanent molars were embedded onto acrylic resin with the dentin surface exposed. Group I was a control group that was conditioned with polyacrylic acid (PAA). Groups II and III were contaminated with saliva before PAA conditioning and Groups IV, V, and VI were contaminated with saliva after PAA conditioning. After saliva contamination, Groups II and IV were dried, Groups III and V were rinsed and dried, and Group VI was additionally conditioned with PAA. After surface treatment, the dentin specimens were filled with RMGI. Group I showed significantly higher bond strength than the other groups. Group VI showed a significantly higher bond strength than the other saliva contaminated groups. However, there were no significant differences in the failure mode between the different groups. Saliva contamination impaired the bond strength of RMGI to dentin, regardless of when the saliva contamination occurred. Decontamination with washing and drying could not improve the shear bond strength of RMGIC. When saliva contamination occurred after PAA conditioning, additional PAA conditioning improved the shear bond strength.

The purpose of this study was to evaluate the effect of application time and phosphoric acid etching of 8th generation adhesives containing functional monomer on adhesive performance in primary teeth. 80 extracted non-carious human primary teeth were selected and divided into 8 groups based on 3 factors: (1) adhesive: G-Premio bond and Single bond universal; (2) application time: shortened time and manufacture’s instruction; (3) acid etching mode: self-etching and total-etching. Shear bond strength was measured using a universal testing machine, and fractured surface were observed under scanning electron microscope. Microleakage was evaluated by dye penetration depth. G-Premio bond were not significant different in shear bond strength and microleakage depending on application time of adhesive and acid etching mode. In Single bond universal, shear bond strength of short application time was significantly lower than that of long adhesive application time (p = 0.014). Clinically applicable shear bond strength values (> 17 MPa) were identified in all groups. These results suggested that G-Premio bond be used clinically for a short application time without phosphoric acid etching.

Vertical facial growth triggers the rotation of mandible to move the chin point to the downward and backward direction, which showed remarkably effective result making the less prominent chin. Recently, the intraoral removable appliance utilizing class Ⅲ elastic demonstrated the vertical growth trigger mechanism. The treatment change was very fast and wearing was quite easy, compared to extraoral appliances. The purpose of this study was to verify the duration of the treatment on class Ⅲ malocclusion using intraoral removable appliances, which designed to accelerate vertical facial growth. 56 patients were selected with the complaint of the protruded mandible and class Ⅲ malocclusion (overjet : -3 - 0 mm, overbite : 0 - 4 mm). Information like; age at start, duration of the treatment events, type of the treatment, overjet, overbite etc. was collected and calculated. The average age of the patients delivering the initial brace was 8.75 ± 1.10 year. Most of the anterior crossbite was resolved within 6 months. The total treatment period was 21.79 ± 10.73 months with the additional procedures like the alignment of anterior teeth and torque control using additional removable and fixed orthodontic appliances. The correlation study showed that patient’s cooperation (p = 0.000) and the use of fixed appliance (p = 0.032) were significantly influenced on treatment duration.

The purpose of this study was to investigate the changes of the position of the mental foramen according to age by using panorama of children with mixed and early permanent dentition. 180 panorama of 6 to 13-year-old boys and girls were analyzed and PiView(Infinitt, Korea) program was used. The horizontal position of the mental foramen was evaluated by the relative position of the teeth. The vertical position of the mental foramen was evaluated by the ratios between the distance from the center of the mental foramen to the inferior border of the mandible and the distance from to the alveolar crest to the inferior border of the mandible. The mental foramen was horizontally located in the anterior aspect of the second primary molar(premolar), and vertically slight below the half of mandibular body. As the age increased, it moved to the posterior and the downward and showed a significant correlation with age.

Carbopol® 907 used as surface protecting agent in White’s method is the one of the artificial caries lesion producing solution was discontinuing of production. New surface protecting material to substitute of Carbopol® 907 was required. The author prepared an artificial caries lesion producing solution as follows White’s method with Carbopol® 907 and also another artificial caries lesion producing solution with Carbopol® 2050®. 96 flattened and polished enamel samples were immersed in a demineralizing solution of 0.1 mol/L lactic acid, 0.2% carboxyvinylpolymer and 50% saturated hydroxyapatite for 1, 2, 3, 4, 5, 6, 7, 9, 11, 15, 18 and 20 days. All samples from each group were subjected to polarized microscopy observed and image analysis for measuring the lesion depth. From the review of polarized images, the artificial caries lesion producing solution using Carbopol® 907 and Carbopol® 2050 can produced an artificial caries that was very similar to natural caries characters. From the regression analysis of the lesion depth produced by the artificial caries lesion producing solution using Carbopol® 907 and Carbopol® 2050, Carbopol® 2050 estimate as Y = 9.8X + 8.0 and Carbopol® 907 was Y = 8.4X – 0.4. R square value of Carbopol® 2050 and Carbopol® 907 was 0.965 and 0.945 respectively. The rate of demineralization by the artificial caries lesion producing solution using Carbopol® 2050 was faster than that of Carbopol® 907. And R square value of Carbopol® 2050 and Carbopol® 907 were very high and it means that the lesion depth was very high coefficient to demineralization period.

The purpose of this study was to analyze the dental consultation of pediatric inpatients to the department of pediatric dentistry in Yonsei University Severance Hospital, and to investigate the change in patterns. In 2017, 268 pediatric patients (384 cases) admitted to the Severance Hospital were referred to the department of pediatric dentistry. The mean age was 6.6 years, and most of the patients were referred from the Department of Pediatric Hematology Oncology and Rehabilitation Medicine. The chief complaints were as follows: oral examination (31%), dental caries (20%), oral pain (10%), tooth mobility (10%), pre-operative evaluation (9%) and others (20%). 41% of the patients received only oral examination without treatment. Dental caries were the most frequent dental diagnosis of the patients. 28% (111 cases) of patients received operative treatments, 22 cases were treated under general anesthesia. Oral health is closely related to systemic diseases, especially for hospitalized patients. Dental consultations should be encouraged for prevention and early appropriate treatments. For this purpose, it is necessary to establish a referral system and perform dental treatment under general anesthesia.

This study was aimed to evaluate orofacial morphologies on the cases of developmental disorders of maxillary first molars. Panoramic radiographs, lateral cephalographs, and clinical photos of 2983 children who attended the Pediatric Dental Clinic of Pusan National University Dental Hospital from 2006 to August 2017 were assessed retrospectively. 34 patients were selected whose maxillary first molars were missed or developmentally delayed unilaterally or bilaterally. Demirjian’ s method was used for estimating dental age, then which was compared to chronologic age of children. Parameters expressing skeletal and dentoalveolar disharmony were checked and compared with control. Additionally, occlusion relationship was evaluated. Maxillary dental age was significantly delayed compared to chronologic age. Several parameters which show skeletal open-bite tendency and skeletal class III malocclusion with maxillary retrusion were statistically significant. Anterior crossbite and edge-bite were expected in most of these cases, but compensation by occlusion and soft tissue was also verified which might mask skeletal class III tendency. Congenital missed or developmentally delayed maxillary first molars might be related with declined growth of maxilla. If developmental disorders of maxillary first molars were verified during clinical examination, careful monitoring of orofacial growth was necessary during puberty and timed orthopedic and orthodontic intervention were considered.

The purpose of this study was to investigate the odontoblast gene expression related to the subculture speed of supernumerary dental pulp stem cells (sDPSCs). The stem cell is undifferentiated cells which has the ability to differentiate into various cells. Specific stimulation or environment induces cell differentiation, and these differentiation leads to bone or muscle formation. 20 sDPSCs were obtained from 20 children under aseptic condition. During the culture through the 10th passage, the third passage cells which showed short subculture period and 10th passage cells which showed long subculture period were earned. Each cell was divided into differentiated group and non-differentiated group. Quantitative real-time polychain reaction (q-RT-PCR) was performed for each group. The genes related to odontoblast differentiation, Alkaline Phosphatase (ALP), Osteocalcin (OCN), Osteonectin (ONT), Dentin sialophosphoprotein (DSPP) and Dentin matrix acidic phosphoprotein 1 (DMP-1), were measured. Differentiated cells showed more gene expression levels. Undifferentiated cells showed higher gene expression level in 10th passages but differentiated cells showed higher gene expression level in 3rd passages. Cells that showed faster subculture period showed relatively lower gene expression level except for OCN and DSPP.

The purpose of this study was to investigate the effect of adding a protective coating on the microhardness and wear resistance of glass ionomer cements (GICs). Specimens were prepared from GIC and resin-modified GIC (RMGI), and divided into 3 groups based on surface protection: (1) no coating (NC), (2) Equia coat coating (EC), and (3) un-filled adhesive coating (AD). All specimens were then placed in distilled water for 24 h. Surface hardness (n = 10) was evaluated on a Vickers hardness testing machine. Wear resistance (n = 10) was evaluated after subjecting the specimen to thermocycling for 10,000 cycles using a chewing simulator. Data were analyzed using a one-way ANOVA and the Kruskal-Wallis test. Surface hardness was highest in the NC groups, followed by the EC and AD groups. The wear depth of GI + NC was significantly higher than that of all RMGI groups. EC did not significantly lower the wear depth compared to AD. Based on these results, it was concluded that although EC does not increase the surface microhardness of GIC, it can increase the wear resistance.