Dong-Seok Nahm

Roles of Salivary Proteins in the Adherence of Oral Streptococci to Various Orthodontic Brackets

Knowledge of salivary pellicles on orthodontic brackets provides a better understanding of microbial adherence. The aim of this study was to analyze the effects of bracket pellicles on the adherence of Streptococcus gordonii and Streptococcus mutans. Bracket pellicles were formed by the incubation of 4 kinds of orthodontic brackets with unstimulated whole saliva for 2 hrs, and analyzed by electrophoresis, immunodetection, and amino acid analysis. Binding assays were then performed by the incubation of tritium-labeled streptococci with the pellicle-transfer blots and orthodontic brackets. The results showed that low-molecular-weight mucin, α-amylase, secretory IgA, acidic proline-rich proteins, and cystatins adhered to all kinds of brackets, though the amino acid composition of pellicles differed between bracket types. Some of these proteins increased the binding of S. gordonii to saliva-coated brackets. However, salivary pellicles decreased the binding of S. mutans. Collectively, salivary pellicles were found to play a significant role in the initial adhesion of oral streptococci to orthodontic brackets.

Classification of the skeletal variation in normal occlusion.

The aims of this study were to classify normal occlusion samples into specific skeletal types and to analyze the dentoalveolar compensation in a normal occlusion in order to provide the clinically applicable differential diagnostic criteria for an individual malocclusion patient. Lateral cephalograms of 294 normal occlusion samples, who were selected from 15,836 adults through a community dental health survey, were measured. Using a principal component analysis, two factors representing the anteroposterior and vertical skeletal relationships were extracted from 18 skeletal variables. Cluster analysis was then used to classify the skeletal patterns into nine types. Nine types of polygonal charts with a profilogram were created. Discriminant analysis with a stepwise entry of variables was designed to identify several potential variables for skeletal typing, which could be linked with computerized cephalometric analysis for an individual malocclusion patient. Discriminant analysis assigned 87.8% classification accuracy to the predictive model. It was concluded that because the range of a normal occlusion includes quite diverse anteroposterior and vertical skeletal relationships, classifying the skeletal pattern and establishing an individual dentoalveolar treatment objective might facilitate clinical practice.

En masse retraction and two-step retraction of maxillary anterior teeth in adult Class I women. A comparison of anchorage loss.

OBJECTIVE To compare the amount of anchorage loss of the maxillary posterior teeth and amount of retraction of the maxillary anterior teeth between en masse retraction and two-step retraction of the anterior teeth. MATERIALS AND METHODS The sample consisted of 30 female adult patients with Class I malocclusion and lip protrusion who needed maximum posterior anchorage. The sample was subdivided into group 1 (n = 15, mean age = 21.4 years, en masse retraction) and group 2 (n = 15, mean age = 24.6 years, two-step retraction). Lateral cephalograms were taken before (T1) and after treatment (T2). Nine skeletal and 10 anchorage variables were measured, and independent t-test was used for statistical analysis. RESULTS Although the amount of horizontal retraction of the maxillary anterior teeth was not different between the two groups, there was mild labial movement of the root apices of the upper incisors in group 2 at T2. There were no significant differences in the degree of anchorage loss of the maxillary posterior teeth between the two groups. Bodily and mesial movements of the upper molars occurred in both groups. Approximately 4 mm of the retraction of the upper incisal edges resulted from 1 mm of anchorage loss in the upper molars in both groups. CONCLUSION No significant differences existed in the degree of anchorage loss of the upper posterior teeth and the amount of retraction of the upper anterior teeth associated with en masse retraction and two-step retraction of the anterior teeth.

Reliability of landmark identification on monitor-displayed lateral cephalometric images.

INTRODUCTION Our objective was to compare the reliability of landmark identification with hard-copied film images vs monitor-displayed images from digital lateral cephalograms. METHODS We randomly selected 50 orthodontic patients. Identification and digitization of the cephalometric landmarks were performed 3 times at 2-week intervals by 2 observers. The 2 methods of landmark identification were the hard-copied film-based method (HFM) and the monitor-displayed method (MDM). Each landmark was expressed as Cartesian coordinates (x and y). Two-factorial repeated measures analysis of variance was used to analyze differences in landmark identification and to estimate the characteristics of the landmarks with high errors. Intraclass correlation coefficients (ICC) were computed to assess interobserver reliability and intraobserver reliability between the methods. RESULTS There were no statistically significant differences in landmark identification between the 2 methods. The only significant differences between the observers were for porion, pogonion, and the most concave point of the anterior border of the ramus of both sides (R1).The interaction between method and observer did not show a significant difference. A test for intraobserver reliability showed excellent ICC of more than 0.910 except for basion and R1 with HFM. However, with MDM, all landmarks had excellent ICC scores of more than 0.98. MDM is better than HFM in situations of higher radiopacity or radiolucency. Assessment of interobserver reliability showed excellent ICC. However, MDM had better reliability than HFM for basion and R1. CONCLUSIONS There was no significant difference in landmark identification between MDM and HFM.

Adhesion of oral streptococci to experimental bracket pellicles from glandular saliva.

The aim of this study was to evaluate the functions of bracket pellicles as the binding receptors for Streptococcus mutans and Streptococcus gordonii. Four different types of orthodontic brackets were used: stainless steel, monocrystalline sapphire, polycrystalline alumina, and plastic. The bracket pellicles were formed by incubating orthodontic brackets with fresh submandibular-sublingual saliva or parotid saliva for 2 hours. The pellicles were extracted, and their components were confirmed by gel electrophoresis, immunodetection, and amino acid composition analysis. The roles of the bracket pellicles in the adhesion of oral streptococci were evaluated by incubating tritium-labeled streptococci with pellicle-transfer blots. The results showed that the salivary components adhered selectively according to type of bracket and glandular saliva. The selective adsorption was also proven by the amino acid composition profiles. Among the several salivary proteins, MG2, alpha-amylase, and the acidic proline-rich proteins provided the binding sites for S gordonii. However, none of these proteins in the bracket pellicles contributed to the adhesion of S mutans. These findings suggest that numerous salivary proteins can adhere selectively to the orthodontic brackets, and some of them contribute to the binding of S gordonii.

Maximum Closing Force of Mentolabial Muscles and Type of Malocclusion

OBJECTIVE To measure the closing force of the upper and lower lips and to ascertain the relationship between the maximum closing force of the mentolabial muscles and types of malocclusion. MATERIALS AND METHODS Of those who showed the full eruption of a second molar and no permanent tooth loss, 99 subjects were chosen who showed a positive overbite and ANB and no skeletal asymmetry. By using the Y-meter, which can measure the lip force in the vertical direction using a load cell, the closing forces of the upper and lower lips were measured separately. A one-way analysis of variance (ANOVA) test and the Pearsons correlation test were used to evaluate the interrelationship between lip force and dentofacial morphology. RESULTS The lip closing force was greater in male and Class I subjects. Upper lip force was greater than that of the lower lip in all groups. The values of lip closing forces were related to the variables of upper incisor angulation. In Class II subjects, the values of lip closing forces were also related to the vertical skeletal pattern. CONCLUSIONS The mentolabial muscle force was highly correlated with dentofacial structure and types of malocclusion.

Analysis of surface roughness and surface free energy characteristics of various orthodontic materials.

INTRODUCTION The purpose of this study was to analyze the differences in surface characteristics of various orthodontic materials; this might provide valuable information on bacterial adhesion to orthodontic materials. METHODS Surface roughness (SR) and surface free energy (SFE) characteristics of 5 orthodontic adhesives (2 composites resins, 2 resin-modified glass ionomer cements, and 1 compomer), 5 bracket materials (2 stainless steel, 1 monocrystalline sapphire, 1 polycrystalline alumina, and 1 plastic) and bovine incisors were investigated by using confocal laser scanning microscopy and the sessile drop method. RESULTS There were significant differences in SR and SFE characteristics among orthodontic materials. Bovine incisors showed the roughest surface, and monocrystalline sapphire showed the smoothest surface. However, there were only small variations in SR (less than 0.3 mum) among the materials, except for bovine incisors. In contrast to SR, there were big differences in SFE characteristics among materials. Generally, bracket materials showed lower SFE--specifically, dispersive and polar components on their surfaces--than orthodontic adhesives. Resin-modified glass ionomer cements had the highest SFE, dispersive component, and polarity; these conditions are more favorable for bacterial adhesion. CONCLUSIONS This study suggests that SFE characteristics can influence bacterial adhesion to orthodontic materials more than SR, and bracket materials might have less favorable SFE characteristics for bacterial adhesion than orthodontic adhesives.

Quantitative determination of adhesion patterns of cariogenic streptococci to various orthodontic adhesives.

OBJECTIVE To investigate the adhesion of various cariogenic streptococci to orthodontic adhesives. MATERIALS AND METHODS Five light-cure orthodontic adhesives (one fluoride-releasing composite, three non-fluoride-releasing composites, and one resin-modified glass ionomer cement) were used. The adhesive type, bacterial strain, incubation time, and saliva coating were studied. Thirty specimens of each adhesive were incubated with unstimulated whole saliva or phosphate-buffered saline for 2 hours. Binding assays were then performed by incubating tritium-labeled streptococci with the adhesives for 3 or 6 hours. RESULTS The results showed a characteristic adhesion pattern according to the type of bacterial strains used. Streptococcus mutans LM7 showed the highest amount of adhesion, whereas S sobrinus B13 showed the lowest amount of adhesion. The cariogenic streptococci adhered to the glass ionomer significantly more than to the composites, whereas there was no significant difference in the adhesion amount among the four composites. The extended incubation time significantly increased bacterial adhesion. However, saliva coating did not significantly alter adhesion patterns of cariogenic streptococci. CONCLUSIONS This study suggests that cariogenic streptococci can adhere diversely according to adhesive type and that the adhesion of the cariogenic streptococci is not influenced by its fluoride-releasing properties.

Cystatins and cathepsin B during orthodontic tooth movement.

INTRODUCTION The lysosomal cysteine protease cathepsin B is known to play an important role in the resolution of organic matrix, a final step in bone resorption. Cystatins function as an inhibitor of cathepsin B. Determining the correlation between cathepsin B and cystatin levels in gingival crevicular fluid at various times might provide a better understanding of both the dynamics and the metabolic stages of orthodontic tooth movement. METHODS Human gingival crevicular fluid was collected at the distal sulcus from the canines of persons not in orthodontic treatment, in retention, and in retraction at various times (initial, 1 day, 1 week, and 1 month postretraction). Cathepsin B and its inhibitor, cystatin, were found with fluorometry. RESULTS The level of cathepsin B was varied in the retraction group; this was different from the retention and the nonorthodontic groups. Significant initial decreases after force application and subsequent increases by 1 month posttreatment were observed in the retraction group. The variations and differences among groups were negatively correlated with cystatin. CONCLUSIONS The balance between enzyme and inhibitor might reflect the clinical status of orthodontic tooth movement and provide valuable information for the assessment of recall intervals and retention procedures.

Differential diagnosis for inappropriate upper incisal display during posed smile: contribution of soft tissue and underlying hard tissue.

The amount of upper incisor display (UID) during smile and conversation is one of the most decisive components in aesthetic judgment. The purpose of this study was to find which soft tissue and underlying hard tissue factors contributed to the amount of UID during posed smile (PS) and at rest posture (RP). The subjects consisted of 76 young adults (33 men and 43 women; mean [SD] age, 24.79 [2.29] y) with skeletal and dental class I relationship, normal overbite/overjet, and minor crowding (<2 mm). After checking reproducibility of the amounts of UID during PS and at RP in lateral cephalograms with facial photographs, 15 hard and soft tissue variables were measured, and statistical analysis was done. There was no significant sex difference in the amount of UID during PS and at RP. The amount of UID during PS significantly increased when anterior maxillary height was longer, lower gonial angle was larger, occlusal plane to sella-to-nasion plane angle was steeper, interlabial gap at RP was larger, upper lip length at RP was shorter and upper lip elevation during PS was larger. Multiple linear regression analysis to predict the degree of UID during PS generated a 4-variable model (adjusted R2 = 0.607): upper lip elevation (the dynamic soft tissue variable), interlabial gap and upper lip length (the static soft tissue ones), and anterior maxillary height (the hard tissue one). The diverse causes of inappropriate UID according to the soft and hard tissue factors need different treatment approaches such as orthodontic treatment, periodontal treatment, orthognathic surgery, botulinum toxin, or myectomy. The clinician can use these variables as a guideline for differential diagnosis of inappropriate UID.