Quantitative analysis of mutans streptococci adhesion to various orthodontic bracket materials in vivo / 대한치과교정학회지

OBJECTIVE: To estimate the effects of bracket material type on enamel decalcification during orthodontic treatment, this study analyzed the adhesion level of mutans streptococci (MS) to orthodontic bracket materials in vivo. METHODS: Three different types of orthodontic bracket materials were used: stainless steel, monocrystalline sapphire, and polycrystalline alumina. A balanced complete block design was used to exclude the effect of positional variation of bracket materials in the oral cavity. Three types of plastic individual trays were made and one subject placed the tray in the mouth for 12 hours. Then, the attached bacteria were isolated and incubated on a mitis salivarius media containing bacitracin for 48 hours. Finally, the number of colony forming units of MS was counted. The experiments were independently performed 5 times with each of the 3 trays, resulting in a total of 15 times. Mixed model ANOVA was used to compare the adhesion amount of MS. RESULTS: There was no difference in colony forming units among the bracket materials irrespective of jaw and tooth position. CONCLUSIONS: This study suggested that the result of quantitative analysis of MS adhesion to various orthodontic bracket materials in vivo may differ from that of the condition in vitro.

Comparison of landmark position between conventional cephalometric radiography and CT scans projected to midsagittal plane / 대한치과교정학회지

OBJECTIVE: The purpose of this study is to compare landmark position between cephalometric radiography and midsagittal plane projected images from 3 dimensional (3D) CT. METHODS: Cephalometric radiographs and CT scans were taken from 20 patients for treatment of mandibular prognathism. After selection of landmarks, CT images were projected to the midsagittal plane and magnified to 110% according to the magnifying power of radiographs. These 2 images were superimposed with frontal and occipital bone. Common coordinate system was established on the base of FH plane. The coordinate value of each landmark was compared by paired t test and mean and standard deviation of difference was calculated. RESULTS: The difference was from -0.14 +/- 0.65 to -2.12 +/- 2.89 mm in X axis, from 0.34 +/- 0.78 to -2.36 +/- 2.55 mm (6.79 +/- 3.04 mm) in Y axis. There was no significant difference only 9 in X axis, and 7 in Y axis out of 20 landmarks. This might be caused by error from the difference of head positioning, by masking the subtle end structures, identification error from the superimposition and error from the different definition. CONCLUSIONS: This study revealed innate shortcomings of radiography. For the development of 3D cephalometry, more study was needed.

Effects of various NSAIDs on prostaglandin synthesis and cellular configuration of human periodontal ligament cells

The present study was designed to evaluate effects of the commonly used NSAIDs(acetaminophen, aspirin, and ibuprofen) on human periodontal ligament cells. Human periodontal ligament cells were grown from a cell line provided by Kyungpook National University. Effects of NSAIDs on the proliferation of human periodontal ligament cells were assessed using MTT assays. And then PGE2 concentrations were determined by ELISA and the changes of cellular configuration were found by electron micrograph. The results were as follows; 1. The MTT assay demonstrated that the commonly used NSAIDs(acetaminophen, aspirin, and ibuprofen) had not significant cytotoxic effect on human periodontal ligament cells. 2. NSAIDs inhibited the PGE2 synthesis of human periodontal ligament cells compared with the control group. These inhibitory effects had no significant differences with NSAID type and concentration. 3. Electron micrographs of human periodontal ligament cells treated with NSAIDs showed more narrow and irregular shape.

Mechanical analysis of the taper shape and length of orthodontic mini-implant for initial stability / 대한치과교정학회지

Orthodontic mini-implants, despite its usefulness as anchorage, have some limits such as loosening. Therefore, various shapes and lengths have been studied. The aim of this study is to analyze the shape and length of mini-implants mechanically. The shapes of mini-implants (1.6 mm, Dual Top, Jeil Medical Co., Seoul, Korea) were cylindrical and taper. The lengths of mini-implants were 6 mm and 8 mm. The tested groups were 5 groups (cylindrical 6 mm, cylindrical 8 mm, taper 6 mm, taper 8 mm and taper 8 mm modified whose thread is reduced from the middle to upper part). All were inserted and removed on the polyurethane foam with the torque measured. During insertion and removal, the taper shape needed higher torque than the cylindrical shape, and the 8 mm length than the 6 mm length (p < 0.001). The taper 6 mm group showed superior insertion torque (p < 0.001) and similar removal torque to the cylindrical 8 mm group. The taper 8 mm modified group with gradually reduced threads, showed continuous high removal torque after the peak. The initial mechanical stability can be provided by the tapered shape and also, affected by length and thread design.

Spacing and crowding of the primary dentition in Korean children - relationship to tooth sizes and dental arch dimension / 대한치과교정학회지

The aims of this study were to investigate the prevalence of spaced, closed, and crowded primary dentitions by sex and arch in Korean children from Kanghwa, and to determine the frequency of the primate and developmental spaces. The differences in the mesiodistal crown diameters and the arch dimensions between the spaced, closed, and crowded primary dentitions were also evaluated. Dental casts of 102 preschool children (57 males and 45 females, aged 4 ~ 5 years) were studied. The prevalence of spacing in the primary dentition was 63.2% in males and 57.8% in females. The frequency of spacing was greater in males than in females, and greater in the maxillary arch than in the mandibular arch. The crowns were significantly larger and the arches significantly narrower in closed and crowded dentitions than in those with spacing (p < 0.05). The results showed that the prevalence of spacing was lower than that found in previous studies and the presence of spacing in the anterior region was related to the mesiodistal crown diameter and the intercanine width.

Comparing locus of control in orthodontic patients of a university dental hospital with those of a private dental clinic / 대한치과교정학회지

OBJECTIVE: Many factors are considered when a patient chooses the type of dental institution they wish to receive treatment from. Numerous studies have been conducted regarding this issue. However, more research is needed in analyzing the patient's psychological aspects when he/she decides to choose the dental institution they wish to receive treatment from. METHODS: A locus of control test was utilized to analyze the psychological aspects in orthodontic patients of a university dental hospital and a private dental clinic. The locus of control test is known to be useful in predicting a human being's behavior. Both intrinsic and extrinsic locus of control tests were carried out in 934 orthodontic patients attending Seoul National University Dental Hospital and 1466 orthodontic patients from a private dental clinic. RESULTS: The orthodontic patients at the university dental hospital showed a stronger extrinsic locus of control compared with those from the private dental clinic. CONCLUSION: The orthodontic patients at the university dental hospital value the doctor as the authority figure and the treatment quality more than those at the private dental clinic.

Surgical orthodontic treatment of skeletal Class III malocclusion using mini-implant: correction of horizontal and vertical dental compensation / 대한치과교정학회지

Treatment of skeletal Class III malocclusion with mini-implant anchorage is discussed in relation to vertical control of the maxillary posterior dentoalveolar region and horizontal control of mandibular anterior teeth. A midpalatal mini-implant provided anchorage for intruding the maxillary posterior teeth. Mandibular mini-implant implants were used to bring about labioversion of mandibular anterior teeth. After mandibular setback surgery, improvement of the facial profile was obtained both horizontally and vertically. Total treatment time was 11 months. Stable occlusion was maintained after 18 months of retention. The effectiveness and efficacy of mini-implants for the treatment of skeletal Class III malocclusion are also discussed.

Identification of bacteria from the peri-implant sulcus of orthodontic mini-implants using 16S rDNA clone library / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the bacterial flora at the peri-implant sulcus of the orthodontic mini-implant placed in the alveolar mucosa with the bacterial flora at the adjacent healthy gingival sulcus. METHODS: Two plaque samples from 7 patients were collected by inserting paper points into the sulcus between the mini-implant and ligature wire connected to the mini-implant head and inflamed alveolar mucosa, and from the gingival sulcus of a healthy tooth adjacent to the mini-implant. RESULTS: Using 16S rDNA clone library, the 24 kinds of bacteria including Haemophilus aphrophilus, Sphingomonas species, Capnocytophaga species, Prevotella melaninogenica, Lachnospiraceae species, Porphyromonas species, Neisseria flava were identified only from the sulcus around the mini-implant. These bacteria constituted only 9.2% of total clones, and the bacteria identified from both the sulcus around mini-implants and the gingival sulcus constituted 80.4% of total clones. Of these bacteria, clones of Prevotella species, Atopobium rimae, Veillonella species, Streptococcus intermedius/constellatus, Streptococcus salivarius were more frequently isolated from the peri-implant sulcus. CONCLUSION: This study suggests that a broad epidemiological study is needed to find causative bacteria which induce inflammation from the peri-implant sulcus.

Effect of dual pitch mini-implant design and diameter of an orthodontic mini-implant on the insertion and removal torque / 대한치과교정학회지

OBJECTIVE: Small orthodontic mini-implants are useful as anchorage. However they have some weaknesses such as loosening. This study was carried out to analyze the mechanical effects of the dual pitch and diameter on the insertion and removal torque of mini-implants. METHODS: The threads of mini-implants were mono and dual pitch. The diameters of mini-implants were 1.4 mm and 1.6 mm. Four groups were tested (mono 1.4 mm, mono 1.6 mm, dual 1.4 mm and dual 1.6 mm). All were inserted and removed on polyurethane foam with the torques being measured. RESULTS: The maximum torque of the dual pitch groups was higher than the mono pitch groups during removal but lower during insertion. The maximum torque of the 1.6 mm diameter groups was higher than the 1.4 mm diameter groups during insertion and removal. The dual pitch 1.4 mm group showed the lowest insertion torque but had similar or superior levels of removal torque to that of the mono pitch 1.6 mm group. CONCLUSIONS: The dual pitch especially showed a continuous high removal torque after the peak. Despite the small diameter, the dual pitch might improve the initial mechanical stability.

Preliminary study on the effect of inflamed TMJ synovial fluid on the intracellular calcium concentration and differential expression of iNOS and COX-2 in human immortalized chondrocyte C28/I2

OBJECTIVE: The objective of this study was to examine the hypothesis that inflammatory synovial fluid from TMJ internal derangement initiates a transient increase in intracellular calcium concentration ([Ca2+]i) in chondrocytes and the induced Ca2+ signaling affects iNOS/COX-2 gene expression patterns following exposure to inflamed synovial fluid. MATERIALS AND METHODS: Two female adult patients with symptoms of TMD who agreed to participate in the study were selected for this study. Immortalized human juvenile costal chondrocyte C-28/I2 was grown to 80% confluency and synovial fluids from two patients were added respectively to culture media for 24 hours at the concentration of 100ng/10ml. Confocal laser scanning microscope (CLSM) was used to examine changes of intracellular calcium concentration ([Ca2+]i). RT-PCR was performed to identify the expression profile of IL-1alpha, iNOS, COX-2. RESULTS: Increased [Ca2+]i was observed in chondrocytes subjected to inflamed synovial fluid compared to control cultures and in respective cultures exposed to inflamed synovial fluids from each patient, IL-1beta, COX-2 mRNA were detected. However, in neither case iNOS mRNA was expressed. IL-1alpha, COX-2, and iNOS mRNA were expressed in control culture. CONCLUSION: Our results show that immortalized chondrocytes cultured with inflamed synovial fluids from patients diagnosed as disc displacement without reduction and limitation in mouth opening showed increased calcium concentration and expression of COX-2 while inhibiting the production of iNOS, which in turn could adversely affect the chondrocytes in at least short term by hindering physiologic role of NO against inflammatory cascades. These findings suggest that inflamed synovial fluid may differentially regulate the transcriptomes of relevant inflammatory mediators, especially iNOS/COX-2 axis in chondrocytes through adjusting calcium transients.

Direct detection of cariogenic streptococci in metal brackets in vivo using polymerase chain reaction / 대한치과교정학회지

Streptococcus mutans and Streptococcus sobrinus are major etiological agents in enamel demineralization around orthodontic appliances. This study was designed to examine the prevalence of these streptococci on orthodontic brackets in vivo using polymerase chain reaction. Four incisor brackets in the upper and lower arches were removed and collected from 80 patients at the time of debonding. The genomic DNA of adhered bacteria was extracted and each dextranase gene of S. mutans and S. sobrinus was amplified using the specific oligonucleotide primers. The results showed that the maxillary incisor brackets were colonized by both cariogenic streptococci to a somewhat higher degree than that taken from the mandible. The prevalence of S. mutans was 50.0% on the maxillary incisor brackets and 33.8% on the mandibular incisor brackets, and that of S. sobrinus was 17.5% and 15.0%, respectively. Both species were detected on the maxillary incisor brackets of 7 patients (8.8%) and the mandibular incisor brackets of 5 patients (6.3%). These results suggest that cariogenic streptococci can adhere to the incisor brackets and may be resident species on the incisor brackets.

Formulation of a reference coordinate system of three-dimensional head and neck images: Part II. Reproducibility of the horizontal reference plane and midsagittal plane / 대한치과교정학회지

This study was performed to investigate the reproducibility of the horizontal and midsagittal planes, and to suggest a stable coordinate system for three-dimensional (3D) cephalometric analysis. Eighteen CT scans were taken and the coordinate system was established using 7 reference points marked by a volume model, with no more than 4 points on the same plane. The 3D landmarks were selected on V works (Cybermed Inc., Seoul, Korea), then exported to V surgery (Cybermed Inc., Seoul, Korea) to calculate the coordinate values. All the landmarks were taken twice with a lapse of 2 weeks. The horizontal and midsagittal planes were constructed and its reproducibility was evaluated. There was no significant difference in the reproducibility of the horizontal reference planes. But, FH planes were more reproducible than other horizontal planes. FH planes showed no difference between the planes constructed with 3 out of 4 points. The angle of intersection made by 2 FH planes, composed of both Po and one Or showed less than 1 degrees difference. This was identical when 2 FH planes were composed of both Or and one Po. But, the latter cases showed a significantly smaller error. The reproducibility of the midsagittal plane was reliable with an error range of 0.61 to 1.93 degrees except for 5 establishments (FMS-Nc, Na-Rh, Na-ANS, Rh-ANS, and FR-PNS). The 3D coordinate system may be constructed with 3 planes; the horizontal plane constructed by both Po and right Or; the midsagittal plane perpendicular to the horizontal plane, including the midpoint of the Foramen Spinosum and Nc; and the coronal plane perpendicular to the horizontal and midsagittal planes, including point clinoidale, or sella, or PNS.

Formulation of a reference coordinate system of three-dimensional (3D) head and neck images: Part I. Reproducibility of 3D cephalometric landmarks / 대한치과교정학회지

The purpose of this study was to redefine the cephalometric landmarks in three-dimensional (3D) images, which are used in orthodontic cephalometric radiography, and to evaluate the reproducibility of each landmark for 3D cephalometric analysis. Eighteen CT scans were taken at the Department of Diagnostic Radiology at Seoul National University Dental Hospital and manipulated with V works 4.0 (Cybermed Inc., Seoul, Korea). The coordinate system was established using 7 reference points, with no more than 4 points on the same plane. These 7 points were generated as a volume model, the voxel size of which was 4 by 4 by 2 (threshold value = 639). The cephalometric landmarks were selected at the multiplanar reformation (MPR) window on the volume mode of V works 4.0. The selected landmarks were exported to V surgery (Cybermed Inc., Seoul, Korea) for the calculation of coordinate values. All the data were taken twice with a lapse of 2 weeks by one investigator. The reproducibility of each landmark was 0.17 ~ 1.21 mm in the x axis, 0.30 ~ 1.53 mm in the y axis, and 0.27 ~ 1.81 mm in the z axis. In all three axes, the range of error was similar. These error ranges were acceptable with regards to the pixel space and slice thickness. The most reproducible points were I points which were selected on the basis of the volume model. The least reproducible points were J points that were defined by sutures.

Three-dimensional analysis of soft and hard tissue changes after mandibular setback surgery in skeletal Class III patients / 대한치과교정학회지

The three-dimensional (3D) changes of bone, soft tissue and the ratio of soft tissue to bony movement was investigated in 8 skeletal Class III patients treated by mandibular setback surgery. CT scans of each patient at pre- and post-operative states were taken. Each scan was segmented by a threshold value and registered to a universal three-dimensional coordinate system, consisting of an FH plane, a mid-sagittal plane, and a coronal plane defined by PNS. In the study, the grid parallel to the coronal plane was proposed for the comparison of the changes. The bone or soft tissue was intersected by the projected line from each point on the gird. The coordinate values of intersected point were measured and compared between the pre- and post-operative models. The facial surface changes after setback surgery occurred not only in the mandible, but also in the mouth corner region. The soft tissue changes of the mandibular area were measured relatively by the proportional ratios to the bone changes. The ratios at the mid-sagittal plane were 77 ~ 102% (p < 0.05). The ratios at all other sagittal planes had similar patterns to the mid-sagittal plane, but with decreased values. And, the changes in the maxillary region were calculated as a ratio, relative to the movement of a point representing a mandibular movement. When B point was used as a representative point, the ratios were 14 ~ 29%, and when Pog was used, the ratios were 17 ~ 37% (p < 0.05). In case of the 83rd point of the grid, the ratios were 11 ~ 22% (p < 0.05).

Effect of the lower third molar on the treatment of Class III malocclusion / 대한치과교정학회지

The purpose of this study was to evaluate the effect of the lower third molar on treatment time and distal en masse movement of the lower dentition in Class III malocclusions. Thirty subjects (9 males and 27 females) were selected, all of whom were diagnosed as Class III malocclusion and treated by fixed appliances without premolar and/or molar extraction. They were divided into three groups. Group 1 consisted of 12 subjects, whose lower third molars were not extracted during the whole orthodontic treatment. Group 2 consisted of 8 subjects, whose lower third molars were extracted after MEAW application and before removal of the orthodontic appliances. Group 3 consisted of 16 subjects, whose lower third molars were extracted before MEAW application. For each subject, overall treatment time and duration of MEAW application were determined. In addition, pre-treatment and post- treatment lateral cephalometric radiographs were analyzed. All data were processed statistically with ANOVA, and the conclusions were as follows: There was no significant difference among the groups in overall treatment time. However, duration of MEAW application was longer in Group 2 than in Group 1 or Group 3. The overjet that was established after orthodontic treatment was largest in Group 3, in which the lower third molars were extracted before MEAW application. After orthodontic treatment, IMPA decreased in Group 3, but increased in Group 1 and Group 2. There was no significant difference among the three groups in the translation of lower second molars. However, the tipping movement of lower second molars was significantly different, highest in Group 2 and lowest in Group 1. Therefore, it is thought to be better for the orthodontic treatment of Class III malocclusions to extract the lower third molars before MEAW application. In Group 2, the mandibular plane angle was decreased as a result of forward rotation of the mandible. This skeletal change was thought to bring about the difficulty of treatment.

Tooth size and arch parameters of normal occlusion in a large Korean sample / 대한치과교정학회지

The aim of this study was to establish normative data on the tooth size and arch parameters of Koreans with normal occlusion. This study employed the dental casts of 296 (male: 179; female 117) normal occlusion samples, who were selected from 15,836 adults through a community dental health survey. The mesiodistal diameters of teeth, arch width, and arch length were measured by digital electronic calipers (accurate to 0.01 mm) and Bolton's indices as well as intermaxillary arch width ratios were calculated. In order to ensure reliability, intra- and inter-examiner error were evaluated. Although our dimensional data showed overt differences between genders, the indices and intermaxillary ratios evaluated were the same. The resultant data obtained were compared with the previous data to reveal whether any changes have occurred over the time. The clinical implication of the present findings was also discussed. This biometric study seemed to provide a clinically applicable diagnostic criteria for an individual malocclusion patient.

Evaluation of various cephalometric measurements to predict the prognosis of early Class III malocclusion treatment / 대한치과교정학회지

The aims of this study were to investigate the differences in the early craniofacial morphology of Class III malocclusions with good, fair and poor occlusal stability and to elucidate a key determinant for distinguishing the cases. Lateral cephalograms of 30 subjects with Class III malocclusion in the mixed dentition were analyzed at the start of treatment (mean age of 8.58+/-1.47). All subjects were re-evaluated after a mean period of 7.50+/-1.94 years comprising active treatment and retention. At this time, the samples were divided into three groups: good (10 subjects), fair (10 subjects) and poor (10 subjects) occlusal stability groups. According to the results of ANOVA, there were significant morphological differences in the early stage among the good, fair and poor occlusal stability groups, especially in variables that represented the vertical skeletal relationships. As well, there were already more dental compensations in the poor occlusal stability group. Stepwise discriminant analysis on the measurements at the time of first observation identified only one predictive variable: AB to mandibular plane angle (AB-MP). With this discriminant function, 83.3% of the original grouped cases were correctly classified and the canonical correlation coefficient was 0.857. In conclusion, AB-MP can be a possible predictor for the eventual prognosis of early Class III treatment. If it is below 60, the prognosis of early Class III treatment is expected to be poor, while if it is above 65, a good prognosis is expected.

Dentoalveolar compensation according to skeletal discrepancy in Normal occlusion / 대한치과교정학회지

The purpose of this study was to investigate the dentoalveolar compensation according to anteroposterior skeletal discrepancy in normal occlusion and to evaluate cephalometric parameters that quantitatively describe dental compensations. The study consisted of 90 subjects (50 males, 40 females) who were selected among specimens of normal occlusion at Seoul National University Dental Hospital, Dept. of Orthodontics. Lateral cephalograms in centric occlusion were traced and digitized for each subject. According to the anteroposterior skeletal pattern, the sample was divided into three groups. Cephalometric data were analyzed for the three groups using the SPSS program. Independent t-test, correlation analysis and regression analysis were carried out. The results were as follows: Dentoalveolar compensation was found in upper and lower incisor inclination and occlusal plane inclination. As the mandible located anterior to the maxilla, the maxillary incisors inclined more labially, the mandibular incisors more lingually, and the occlusal plane continued to flatten. The dental parameters most correlated with anteroposterior skeletal discrepancy were L1 to SN and L1 to FH. Among the compensatory dentoalveolar changes, lower incisor inclination was strongly related to the anteroposterior jaw relationship and played an important role in obtaining a normal incisor relationship. U1 to PtGn and L1 to APog were constant irrelevant to anteroposterior skeletal discrepancy.

Analysis of dentoalveolar compensation and discrimination of skeletal types / 대한치과교정학회지

The purpose of this study is to analyze dentoalveolar compensation in normal occlusion samples previously classified into 9 skeletal types, and to provide clinically applicable diagnostic criteria for individual malocclusion patients. Cephalometric measurements of the 294 normal occlusion samples previously divided into 9 types were analyzed. The descriptive features of dentoalveolar variables were compared for the 9 types using analysis of variance, followed by post hoc multiple comparisons. In addition, the correlation between skeletal and dentoalveolar variables were analyzed. Discriminant analysis with a stepwise entry of variables was designed to find out several potential variables for use in skeletal typing. The dentoalveolar compensation pattern of the skeletal types varied, especially with regards to the variables that indicated the inclination of incisors and the occlusal plane. Stepwise variable selection identified four variables: AB- MP, SN-AB, PMA and ANB. Discriminant analysis assigned a classification accuracy of 87.8% to the predictive model. On the basis of these results, this study could provide rudimentary information for the development of diagnostic criteria and treatment guidelines for individual skeletal types.

Current trends in orthodontic patients in Seoul National University Dental Hospital / 대한치과교정학회지

Over the past decades, the number of patients seeking orthodontic treatment has increased markedly with socioeconomic development and change of recognition on appearance. The purpose of this study was to provide an epidemiologic data base related to the orthodontic treatment need. We could take an adequate information regarding the characteristics of orthodontic patients, and the changing trends about treatment mordality. Distrubution and treands were investigated in 676 patients who had been examined and diagnosed at Department of orthodontics, Dental Hosital, Seoul National University from January to June in 1992 and 2002. 1. Sex distribution of patients changed from 1 : 2.1 to 1 : 1.5 (male : female). 2. In 2002, age distribution had shown 7~12 year-old group being the largest (32.0%) and percentage of 19~24, 13~18, over 25, 4~6, 0~3 year-old group were 24.0%, 21.6%, 14.2%, 5.8%, 2.4% respctively. Compared with data in 1992, the number of adult patients highly increased. 3. With regard to Angle classification, each percentage of Class I , Class II div 1, Class II div 2, and Class III malocclusion were 25.0%, 20.9%, 3.4%, and 48.1% respectively in 2002. 4. Geographic distribution showed that most of the patients visited (37.0%) lived in northeast of Seoul in 2002. 5. Mandibular prognathism showed the highest percentage in chief complaints. The percentages of crowding and facial asymmetry were 14.2% and 11.8% in 2002. Patients with facial asymmetry increased significantly. 6. Percentages of patients treated with fixed appliance and orthognathic surgery were 38.0% and 25.0% in 2002. Patients needed to observe the growth pattern comprised 13.0% with increasing trends. The use of chin cap reduced and the percentage of orthognathic surgery and growth observation increased significantly.