The relation between idiopathic scoliosis and the frontal and lateral facial form.

OBJECTIVE: The purpose of this study was to evaluate the relation between idiopathic scoliosis and facial deformity in the horizontal, vertical, and anteroposterior planes. METHODS: A total of 123 female patients aged 14 years or older, who visited the Spine Clinic at the Department of Orthopedics, Korea University Guro Hospital for treatment of idiopathic scoliosis, were enrolled. Whole-spine anteroposterior and lateral radiographs were taken with the patient in a naturally erect position, and frontal and lateral cephalograms were taken in an erect position with the Frankfort horizontal line parallel to the floor. Scoliosis was classified according to the Cobb angle and Lenke classification of six curve types. Cephalometric tracing in all cases was carried out with V-Ceph 5.5 by the same orthodontist. The Kruskal-Wallis test was performed to determine whether any relation existed between each group of the idiopathic scoliosis classification and the cephalometric measurements of frontal and lateral cephalograms. RESULTS: The measurements did not reveal any significant association between the Cobb angle and cephalometric measurements and between the curve type based on the Lenke classification and cephalometric measurements. CONCLUSIONS: Based on the results of this study, no apparent relation was observed between the severity of scoliosis and facial form variations in idiopathic scoliosis patients.

The predictability of dentoskeletal factors for soft-tissue chin strain during lip closure.

OBJECTIVE: To investigate the dentoskeletal factors which may predict soft-tissue chin strain during lip closure. METHODS: The pretreatment frontal and lateral facial photographs and lateral cephalograms of 209 women (aged 18-30 years) with Angle's Class I or II malocclusion were examined. The subjects were categorized by three examiners into the no-strain and strain groups according to the soft-tissue chin tension or deformation during lip closure. Relationships of the cephalometric measurements with the group classification were analyzed by logistic regression analysis, and a classification and regression tree (CART) model was used to define the predictive variables for the group classification. RESULTS: The lower the value of the overbite depth indicator (ODI) and the higher the values of upper incisor to Nasion-Pogonion (U1-NPog, mm), overjet, and upper incisor to upper lip (U1-upper lip, mm), the more likely was the subject to be classified into the strain group. The CART showed that U1-NPog was the most prominent predictor of soft-tissue chin strain (cut-off value of 14.2 mm), followed by overjet. CONCLUSIONS: To minimize strain of the soft-tissue chin, orthodontic treatment should be oriented toward increasing the ODI value while decreasing the U1-NPog, overjet, and U1 upper lip values.

The effect of silver ion-releasing elastomers on mutans streptococci in dental plaque.

OBJECTIVE: The purpose of this study was to investigate the antimicrobial effect of silverized elastomers on mutans streptococci in dental plaque. METHODS: Forty patients undergoing orthodontic treatment were randomly placed into 1 of 2 groups. We examined the maxillary right and left central incisors and premolars, and the mandibular right and left canines of all participants. We ligated the right maxillary and left mandibular teeth of the participants in group 1 with silverized elastomers and ligated their contralateral teeth with conventional elastomers. We ligated the left maxillary teeth and right mandibular teeth of group 2 participants with silverized elastomers. Each participant visited the clinic 4 times at 3-week intervals. We applied the elastomers to the teeth on one side of each patient's mouth during their first visit. During the second visit, the elastomers were removed for microbiological analysis and replaced with steel ligatures. During the third visit, we used silverized elastomers to ligate the teeth contralateral to those treated on the first visit. The elastomers were removed during the fourth visit, and microbiological analyses were performed. We compared the quantity of bacteria on silverized and conventional elastomers at the 0.05 level of significance. RESULTS: The percentage of mutans streptococci was not significantly different in cultures of dental plaque from the silverized and the conventional elastomers (p > 0.05). CONCLUSIONS: There was no significant difference between the antimicrobial effect of the silverized elastomers and that of the conventional elastomers.

Influence of orthodontic adhesives and clean-up procedures on the stain susceptibility of enamel after debonding.

OBJECTIVE: To determine the influence of the type of orthodontic adhesive system, such as conventional acid-etching (CE) and self-etching primers (SEPs), on the stain susceptibility of enamel surface after debonding. Effects of clean-up procedures on the enamel surface were also determined. MATERIALS AND METHODS: Two types and four brands of adhesive systems were investigated using 135 human premolars. Unbonded teeth were used as controls. Three-dimensional scanning of the enamel surface was performed before bracket bonding, after debonding, and after clean-up procedures. The color of each tooth was measured before bracket bonding and again after debonding and clean-up procedures. This was followed by methylene blue staining. The stain susceptibility of the enamel surface was measured after finishing only (F-condition) and after finishing/polishing (FP-condition). RESULTS: After debonding, the amount of residual adhesive resins in CE materials was greater than that in SEP materials. For the F-condition, staining color change in SEP materials was significantly higher than that in CE materials. For the FP-condition, staining color change in both CE and SEP materials was not different from those of the control. CONCLUSIONS: The SEP system would show less stain susceptibility if the thin residual adhesive resin layer after debonding is removed by polishing.

Three-dimensional evaluation of soft tissue change gradients after mandibular setback surgery in skeletal Class III malocclusion.

OBJECTIVE: To evaluate whether mandibular setback surgery (MSS) for Class III patients would produce gradients of three-dimensional (3D) soft tissue changes in the vertical and transverse aspects. MATERIALS AND METHODS: The samples consisted of 26 Class III patients treated with MSS using bilateral sagittal split ramus osteotomy. Lateral cephalograms and 3D facial scan images were taken before and 6 months after MSS, and changes in landmarks and variables were measured using a Rapidform 2006. Paired and independent t-tests were performed for statistical analysis. RESULTS: Landmarks in the upper lip and mouth corner (cheilion, Ch) moved backward and downward (respectively, cupid bow point, 1.0 mm and 0.3 mm, P < .001 and P < .01; alar curvature-Ch midpoint, 0.6 mm and 0.3 mm, both P < .001; Ch, 3.4 mm and 0.8 mm, both P < .001). However, landmarks in stomion (Stm), lower lip, and chin moved backward (Stm, 1.6 mm; labrale inferius [Li], 6.9 mm; LLBP, 6.9 mm; B', 6.7 mm; Pog', 6.7 mm; Me', 6.6 mm; P < .001, respectively). Width and height of upper and lower lip were not altered significantly except for a decrease of lower vermilion height (Stm-Li, 1.7 mm, P < .001). Chin height (B'-Me') was decreased because of backward and upward movement of Me' (3.1 mm, P < .001). Although upper lip projection angle and Stm-transverse projection angle became acute (Ch(Rt)-Ls-Ch(Lt), 5.7 degrees; Ch(Rt)-Stm-Ch(Lt), 6.4 degrees, both P < .001) because of the greater backward movement of Ch than Stm, lower lip projection angle and Stm-vertical projection angle became obtuse (Ch(Rt)-Li-Ch(Lt), 10.8 degrees ; Ls-Stm-Li, 23.5 degrees , both P < .001) because of the larger backward movement of Li than labrale superius (Ls). CONCLUSIONS: Three-dimensional soft tissue changes in Class III patients after MSS exhibited increased gradients from upper lip and lower lip to chin as well as from Stm to Ch.

Skeletal changes of maxillary protraction without rapid maxillary expansion.

OBJECTIVE: To determine potential differences in treatment efficiencies of face mask therapy without rapid maxillary expansion (RME) at different early dental stages. MATERIALS AND METHODS: Forty-nine Class III children who were treated with a face mask without RME were divided into two groups according to their pretreatment dental stage. The primary dentition treatment group consisted of 26 subjects and the mixed dentition treatment group consisted of 23 subjects. Lateral cephalograms before treatment (T0), at the end of treatment (T1), and at least 1 year after the end of treatment (T2) were calculated and analyzed. Fourteen cephalometric variables were evaluated by t-test to identify any significant differences in skeletal changes between the two groups during T1-T0, T2-T1, and T2-T0. RESULTS: The primary dentition group showed not only a greater response to maxillary protraction without RME than did the mixed dentition group during T1-T0, but also a greater relapse tendency during T2-T1. As a result, no significant differences were noted between the two groups in the treatment effects of face masks without RME over the time period T2-T0. CONCLUSION: This study suggests that face mask therapy without RME may be postponed to the early to mid mixed dentition period because the therapy induces similar skeletal changes when initiated at primary or mixed dentition.

Three-dimensional evaluation of soft tissue changes after mandibular setback surgery in class III malocclusion patients according to extent of mandibular setback, vertical skeletal pattern, and genioplasty.

OBJECTIVE: To investigate the 3-dimensional (3D) changes in the soft tissue after mandibular setback surgery (MSS). STUDY DESIGN: Thirty-three skeletal class III malocclusion (SCIII) patients treated with MSS (bilateral sagittal split ramus osteotomy) were subdivided according to extent of MSS, vertical skeletal pattern (VP), and vertical-reduction genioplasty. Lateral cephalograms and 3D facial scan images were taken before and 6 months after surgery. Linear and angular variables were measured with Rapidform 2006 (Inus Technology). RESULTS: After MSS, there were significant increases in the upper lip length and decreases in the lower lip length in the large setback, hypodivergent, and genioplasty groups. The mentolabial fold deepened less in the genioplasty group than in other groups. Although there was no skeletal advancement of the maxilla, the soft tissue convexity in the paranasal area increased more in the hyperdivergent group than in the hypodivergent group after MSS. CONCLUSION: The extent of MSS, VP, and genioplasty could be used as guidelines for 1- and 2-jaw surgeries in SCIII borderline cases.

Three-dimensional quantification of adhesive remnants on teeth after debonding.

INTRODUCTION: The objective of this study was to determine 3 dimensionally the amount of adhesive remaining on teeth after debonding orthodontic brackets. METHODS: Three kinds of adhesives were investigated. Metal brackets were bonded to 45 extracted premolars (15 for each adhesive). Labial surfaces of the teeth were scanned before bonding and after debonding. Remaining volume, maximum height, mean maximum height, and mean height of the adhesive remaining on the tooth after debonding were determined, and adhesive remnant index (ARI) scores were measured. Data were analyzed with the Kruskal-Wallis test. Regression analysis was performed between each parameter for the remaining adhesive and the ARI. RESULTS: Scanned profiles of the tooth surfaces after debonding showed the remaining adhesive clearly. Volume and mean height were significantly different by the type of adhesive (P <0.05). For the ARI scores, 2 resin-based adhesives showed similar trends; however, a smaller portion of the resin-modified glass ionomer adhesive remained on the teeth. Parameters for remaining adhesive and ARI scores showed significant correlations (r = 0.332-0.486; P <0.05). CONCLUSIONS: Quantitative data for the remaining adhesive provides more detailed information about the debonded enamel surface.

Force delivery properties of thermoplastic orthodontic materials.

INTRODUCTION: Our objectives were to evaluate the force and energy (resilience) delivery properties of thermoplastic overlay orthodontic materials and to determine the changes in force delivery properties after thermocycling or repeated load cycling. METHODS: Three types and 3 thicknesses of materials were investigated. Three-point bending-recovery tests were performed at baseline and after cycling procedures. For cycling, the specimens were thermocycled for 1000 cycles or repeatedly deflected by 1 mm for 100 cycles. Vickers hardness was measured to determine the changes after thermocycling or repeated load cycling. RESULTS: The amount of deflection for optimal force delivery was 0.2 to 0.5 mm. Thin material exerted high energy in the deflection range of optimal force delivery. In the deflection ranges of optimal force delivery (0.2-0.5 mm), the force delivery properties after thermocycling were not different from those at the baseline (P >.01) but were different after repeated load cycling (P <.01). Thermocycling and repeated load cycling influenced Vickers hardness significantly. CONCLUSIONS: Thin material (0.508 mm) can deliver higher energy than thick materials (0.762 or 1.016 mm, P <.01) of the same brand. Therefore, thin material should be selected in the same brand of material. The effect of repeated deflection during service should be considered.

Influence of filler distribution on the color parameters of experimental resin composites.

OBJECTIVES: Simulating the optical properties of natural tooth would be the final goal for esthetic restorative materials. Filler distribution in resin composites determines the scattering in composite materials, which in turn would influence the color parameters such as lightness, chroma and hue. The objective of this study was to determine the influence of filler size and amount on the color parameters of experimental resin composites. METHOD: Color of 11 experimental resin composites with two different sized fillers (LG: 0.77 microm and SG: 0.50 microm) in 10-70 wt% was measured by a spectrophotometer. Color coordinates (CIE L*, a* and b*), chroma and hue angle were determined. Optical constants including scattering coefficient (S), absorption coefficient (K) and light reflectivity (RI) were calculated. To determine the influence of the amount of filler on the optical parameters, Pearson correlations between the amount of filler (%) and color parameters and optical constants were calculated. Correlations between the optical constants (S, K and RI) and color parameters were calculated (p<0.05). RESULTS: S value increased as the amount of filler increased. RI value generally increased as the amount of filler increased for LG filler group, and increased up to 40% filler for SG filler group. CIE L* value increased as the amount of filler increased in both of LG and SG filler groups. CIE L* value was highly correlated with S and RI values for both filler groups (r=0.961-0.974). CONCLUSION: Lightness was highly correlated with the amount of filler, S and RI values (r=0.932-0.974). But the correlation coefficients between the amount of filler and chroma/hue were moderate (r=0.406-0.827); therefore, pigmentation would be tried to simulate the color of resin composites to those of natural tooth. Optical properties of resin composites could be partly simulated to those of teeth by controlling the filler distribution.

Effect of surface treatment and type of cement on the retentive strength of orthodontic bands on gold alloy crowns.

INTRODUCTION: The objective of this study was to evaluate the effect of surface treatment of gold alloy crowns and type of cement on the retentive strength of orthodontic bands cemented on gold alloy crowns. METHODS: Two hundred eight crowns, made of type IV dental gold alloy, were divided into 16 groups based on surface treatment (C, no treatment; S, sandblasting; V, V-Primer; and S + V, sandblasting and V-Primer) and band cement (resin-modified glass ionomer cement, compomer, composite resin, and adhesive resin cement). Bands were cemented on the crowns, and tensile loads were applied to measure the retentive strength. Two-way analysis of variance (ANOVA) was performed for the retentive strength with the factors of surface treatment and type of cement, and the Scheffé multiple comparison test was performed as a post-hoc test (alpha = 0.05). RESULTS: The retentive strength of the bands was influenced by surface treatment and type of cement, and there was significant interaction between the 2 variables based on 2-way ANOVA (P <.05). Resin-modified glass ionomer cement showed the highest retentive strength regardless of surface treatment (>1.26 MPa). CONCLUSIONS: Resin-modified glass ionomer cement is the most desirable cement for attaching a band to a gold alloy crown. When an adhesive resin cement is used, sandblasting of the gold crown is recommended.

Influence of light transmittance and background reflectance on the light curing of adhesives used to bond esthetic brackets.

INTRODUCTION: The objectives of this study were to determine the correlation between diffuse light transmittance (DLT) of esthetic brackets and the degree of cure (DC) of light-cured adhesives after direct irradiation, and to evaluate the influence of background reflectance. The influences of curing unit and irradiation time were also determined. METHODS: The DLT of 4 ceramic and 4 plastic brackets was measured. Two reference light-curing protocols (cured over a glass slab; mean reflectance, 14.7%) and 4 experimental protocols (cured over bovine tooth slab; mean reflectance, 66.5%) were followed with 3 curing units: halogen, plasma arc, and light-emitting diode. The DC of 2 adhesives was calculated based on Fourier transform infrared spectroscopy. Two-way analysis of variance for the DC was performed (P = .05). The Pearson correlation between the DC and the DLT was determined. RESULTS: Mean DLTs were 44.9% to 75.9%. DC varied by bracket and curing protocol (P <.05) and also by adhesive. In the experimental protocols, there was no significant linear correlation between the DLT and the DC in both adhesives except 1 among 8 groups. The difference in reflectance of background influenced DC (P <.05). CONCLUSIONS: Based on this clinically simulated model, it was confirmed that the reflectance of the background tooth influenced the DC, instead of the DLT of a bracket. The interaction of the DLT and the reflectance of the background tooth on the light curing of adhesives should be studied further.

Fluorescent emission of varied shades of resin composites.

OBJECTIVES: The objectives of this study were to measure the fluorescent emission and the corresponding color difference by the inclusion and exclusion of the UV component of the standard illuminant D65 of varied shades of commercial resin composites, and to determine the influence of the color parameters and difference in color parameters by the UV component on the color difference caused by the fluorescent emission. METHOD: Eight light-curing resin composites, a total of 41 shades, were studied. Color and spectral reflectance of specimens, 12 mm in diameter and 1mm in thickness, were measured on a reflection spectrophotometer. An UV filter was adjusted to 100% or 0% location to include or exclude the UV component of the standard illuminant D65. From the spectral reflectance values, subtraction spectrum by the inclusion or exclusion of the UV component was calculated, and fluorescence peak height was determined. Color difference caused by the inclusion or exclusion of the UV component (DeltaE*(ab)-FL) was calculated. Differences in color coordinates (DeltaL*, Deltaa* and Deltab*) by the inclusion or the exclusion of the UV component were calculated. RESULTS: Fluorescence peak height and DeltaE*(ab)-FL were influenced by the brand and the shade of resin composites and there was a significant interaction between the variables based on two-way ANOVA (p<0.05). DeltaE*(ab)-FL was correlated with the chroma component of the shade, and also with Deltab* [standardized partial correlation coefficient (beta)=-0.699], DeltaL* (beta=0.464) and Deltaa* (beta=0.105) based on multiple regression analyses (p<0.05). CONCLUSION: Fluorescent emission was influenced by the brand and the shade of resin composites. Fluorescent resin composites showed color shift to blue direction and increased lightness under the UV included illumination.

Changes in scattering and absorption properties of esthetic filling materials after aging.

OBJECTIVES: Assuming that color changes after aging are related to changes in translucency of materials, the purpose of the present study was to determine the correlation between the changes in color and the changes in scattering and absorption properties after accelerated aging with representative dental esthetic restorative materials: glass ionomer, resin-modified glass ionomer, compomer, and resin composite. METHODS: Color was measured according to the CIELAB color scale in the transmittance and reflectance modes and used to calculate changes in color (deltaE*(ab)), color coordinates (deltaL*, delta a*, and delta b*), translucency parameter (deltaTP), scattering coefficient (deltaS), absorption coefficient (deltaK), and light reflectivity (deltaRI) after accelerated aging. Simple correlations between each pair of the changes in optical values were calculated, and multiple regression analysis was used to determine the parameters influencing the changes in color and color coordinates (p = 0.05). RESULTS: In the resin composite and compomer, deltaS, deltaK, and deltaRI values were approximately zero, whereas deltaS was as high as 8.9 in the glass ionomer. For most comparisons, correlation coefficient (r) was between 0.700 and 0.997. DeltaL* was found to have a major influence on color changes, and deltaS, deltaTP, and deltaRI influenced deltaL*. Therefore, changes in scattering and absorption properties, after aging, were closely correlated with changes in color and color coordinates, especially in glass ionomer-based filling materials.

Comparison of the color of natural teeth measured by a colorimeter and Shade Vision System.

OBJECTIVES: The objectives were to measure the difference in the color and color parameters of natural teeth measured by a tristimulus colorimeter (CM, used as a reference) and Shade Vision System (SV), and to determine the influence of color parameters on the color difference between the values measured by two instruments. METHOD: Color of 12 maxillary and mandibular anterior teeth was measured by CM and SV for 47 volunteers (number of teeth=564). Color parameters such as CIE L*, a* and b* values, chroma and hue angle measured by two instruments were compared. Chroma was calculated as C*ab=(a*2 = b*2)1/2, and hue angle was calculated as h degrees =arctan(b*/a*). The influence of color parameters measured by CM on the color difference (DeltaE*(ab)) between the values measured by two instruments was analyzed with multiple regression analysis (alpha=0.01). RESULTS: Mean DeltaE*(ab) value between the values measured by two instruments was 21.7 (+/-3.7), and the mean difference in lightness (CIE L*) and chroma was 16.2 (+/-3.9) and 13.2 (+/-3.0), respectively. Difference in hue angle was high as 132.7 (+/-53.3) degrees . Except for the hue angle, all the color parameters showed significant correlations and the coefficient of determination (r(2)) was in the range of 0.089-0.478. Based on multiple regression analysis, the standardized partial correlation coefficient (beta) of the included predictors for the color difference was -0.710 for CIE L* and -0.300 for C*(ab) (p<0.01). CONCLUSION: All the color parameters showed significant but weak correlations except for hue angle. When lightness and chroma of teeth were high, color difference between the values measured by two instruments was small. Clinical accuracy of two instruments should be investigated further.

The electrically non-contacting ECG measurement on the toilet seat using the capacitively-coupled insulated electrodes.

The studies of ECG measurement on the toilet seat have been performed specifically for the ubiquitous health care. Instead of the mainly used dry electrodes having several problems such as the electrical safety or the environmental stability, we used the capacitively-coupled insulated electrodes, which were composed of the Cu plate and the PTFE film for the measurement. The biosignal sensed with the insulated electrodes was measured through the ultra-high input impedance system including OPA111 having the common mode impedance of 10/sup 14/ Omega ft. As the result of measuring the signal, with the electrical ground on the neck or the hand, the R-peaks were detected very positively. However, without the electrical ground on the body, we could detect the heartbeat signal, a land of the motion artifacts by the variation of the blood vessel volume. It seems that this heartbeat signal can be also used as the important parameter like the R-peaks for the HRV (heart rate variability) analysis. In addition, it is thought that, without the directly electrical ground, the R-peak detection will be possible by the improvement of the SNR with the active common canceling system.

The ECG measurement in the bathtub using the insulated electrodes.

The ECG recording in the bathtub was studied using insulated electrode. Prior studies of the ECG recording in the bathtub used conductive electrodes having some problems such as the possibility of the electric shock and sensitivity to contamination of the electrode surfaces. The insulated electrodes were made of copper plate coated with PET film. The electrodes were attached on bathtub at both sides of the chest. High-input-impedance amplifier was designed to amplify ECG signal sensed by insulated electrodes of high impedance. The recorded signals in this study were noisier than those recorded with conventional conductive electrodes. But the R peaks in the recorded signals were large enough to be auto-detected. Further study will improve SNR by reducing of power line noise and common-mode noise.