Changes in buccal facial depth of female patients after extraction and nonextraction orthodontic treatments: A preliminary study / 대한치과교정학회지

OBJECTIVE: This study was performed to investigate buccal facial depth (BFD) changes after extraction and nonextraction orthodontic treatments in post-adolescent and adult female patients, and to explore possible influencing factors. METHODS: Twelve and nine female patients were enrolled in the extraction and nonextraction groups, respectively. Changes in BFD in the defined buccal region and six transverse and two coronal measuring planes were measured after registering pretreatment and posttreatment three-dimensional facial scans. Changes in posterior dentoalveolar arch widths were also measured. Treatment duration, changes in body mass index (BMI), and cephalometric variables were compared between the groups. RESULTS: BFD in the buccal region decreased by approximately 1.45 mm in the extraction group, but no significant change was observed in the nonextraction group. In the extraction group, the decrease in BFD was identical between the two coronal measuring planes, whereas this differed among the six transverse measuring planes. Posterior dentoalveolar arch widths decreased in the extraction group, whereas these increased at the second premolar level in the nonextraction group. The treatment duration of the extraction group was twice that of the nonextraction group. No differences were found in BMI and Frankfort horizontal-mandibular plane angle changes between the groups. BFD changes in the buccal region moderately correlated with treatment duration and dental arch width change. CONCLUSIONS: BFD decreased in adult female patients undergoing extraction, and this may be influenced by the long treatment duration and constriction of dentoalveolar arch width. However, nonextraction treatment did not significantly alter BFD.

A Morphometric Study of the Stainless Steel Permanent Molar Crown with Three-Dimensional Scanner / 대한치과재료학회지

The aim of this study was to compare the morphological characteristics of two types of stainless steel permanent molar crowns using three-dimensional scanners and the morphological changes of these crowns after crimping. Two types of stainless steel permanent molar crowns, PO-96 and PERMACROWN were scanned using three-dimensional scanner. Crown size, crown index (ratio of buccolingual diameter to mesiodistal diameter at height of contour), cervical convergency of crown were measured. Stainless steel crowns were crimped and re-scanned with three-dimensional scanner. Morphological changes of stainless steel permanent molar crowns were analyzed. As for the crown index, maxillary PERMACROWN was larger buccolingually and smaller mesiodistally than maxillary PO-96 and mandibular PERMACROWN was smaller buccolingually and larger mesiodistally than mandibular PO-96. Maxillary PO-96 was more convergent to cervical mesiodistally than maxillary PERMACROWN and mandibular PO-96 was more convergent to the cervical mesiodistally, buccolingually than mandibular PERMACROWN. Both types of stainless steel permanent molar crowns showed reduction of cervical circumference after crimping. Two products were morphologically different in crown size, shape and cervical convergence. Although both types of stainless steel permanent molar crowns are pre-contoured type, additional crimping is needed to achieve better marginal adaptation.

The sagittal morphological and clinical application study of nose in Chinese / 中华整形外科杂志

Objective@#The purpose of this study is to analyze the nasal morphological characteristics in Chinese adult, of Han nationality, by the measurements in sagittal plan and the proportionality between nose and facial structures, in order to provide aesthetic references for rhinoplasty, and individual surgical planning.@*Methods@#During 2017 November to December, 258 healthy Han Youth volunteers were included. Three-dimensional (3D) models of the facial characteristic information were collected using Artec 3D scanner, by standardized procedures. The nasal and facial distances and angulations were measured, based on predesigned facial landmarks. Thereafter, the proportions of above measurements were calculated.@*Results@#There was no significant difference between genders in absolute prominence. As for relative prominence, male nose is more prominent, resulted in a more stereoscopic facial profile. The nasal basal plane of both male and female, was more anterior than the infraorbital points, with 7% of the absolute degree of the infraorbital points. The range of the angle between the nasal basal plane and coronal plane was 2-4 degrees.@*Conclusions@#This study sets a database for the external nasal characteristics of the young adult in Chinese Han nationality, which could provide quantitative references for preoperative evaluation and individually surgical planning.

A comparison of the precision of three-dimensional images acquired by 2 digital intraoral scanners: effects of tooth irregularity and scanning direction / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to compare the precision of three-dimensional (3D) images acquired using iTero(R) (Align Technology Inc., San Jose, CA, USA) and Trios(R) (3Shape Dental Systems, Copenhagen, Denmark) digital intraoral scanners, and to evaluate the effects of the severity of tooth irregularities and scanning sequence on precision. METHODS: Dental arch models were fabricated with differing degrees of tooth irregularity and divided into 2 groups based on scanning sequence. To assess their precision, images were superimposed and an optimized superimposition algorithm was employed to measure any 3D deviation. The t-test, paired t-test, and one-way ANOVA were performed (p < 0.05) for statistical analysis. RESULTS: The iTero(R) and Trios(R) systems showed no statistically significant difference in precision among models with differing degrees of tooth irregularity. However, there were statistically significant differences in the precision of the 2 scanners when the starting points of scanning were different. The iTero(R) scanner (mean deviation, 29.84 +/- 12.08 microm) proved to be less precise than the Trios(R) scanner (22.17 +/- 4.47 microm). CONCLUSIONS: The precision of 3D images differed according to the degree of tooth irregularity, scanning sequence, and scanner type. However, from a clinical standpoint, both scanners were highly accurate regardless of the degree of tooth irregularity.

Accuracy of Bolton analysis measured in laser scanned digital models compared with plaster models (gold standard) and cone-beam computer tomography images / 대한치과교정학회지

OBJECTIVE: The aim of this study was to compare the accuracy of Bolton analysis obtained from digital models scanned with the Ortho Insight three-dimensional (3D) laser scanner system to those obtained from cone-beam computed tomography (CBCT) images and traditional plaster models. METHODS: CBCT scans and plaster models were obtained from 50 patients. Plaster models were scanned using the Ortho Insight 3D laser scanner; Bolton ratios were calculated with its software. CBCT scans were imported and analyzed using AVIZO software. Plaster models were measured with a digital caliper. Data were analyzed with descriptive statistics and the intraclass correlation coefficient (ICC). RESULTS: Anterior and overall Bolton ratios obtained by the three different modalities exhibited excellent agreement (> 0.970). The mean differences between the scanned digital models and physical models and between the CBCT images and scanned digital models for overall Bolton ratios were 0.41 +/- 0.305% and 0.45 +/- 0.456%, respectively; for anterior Bolton ratios, 0.59 +/- 0.520% and 1.01 +/- 0.780%, respectively. ICC results showed that intraexaminer error reliability was generally excellent (> 0.858 for all three diagnostic modalities), with < 1.45% discrepancy in the Bolton analysis. CONCLUSIONS: Laser scanned digital models are highly accurate compared to physical models and CBCT scans for assessing the spatial relationships of dental arches for orthodontic diagnosis.

Accuracy and precision of integumental linear dimensions in a three-dimensional facial imaging system / 대한치과교정학회지

OBJECTIVE: A recently developed facial scanning method uses three-dimensional (3D) surface imaging with a light-emitting diode. Such scanning enables surface data to be captured in high-resolution color and at relatively fast speeds. The purpose of this study was to evaluate the accuracy and precision of 3D images obtained using the Morpheus 3D(R) scanner (Morpheus Co., Seoul, Korea). METHODS: The sample comprised 30 subjects aged 24-34 years (mean 29.0 +/- 2.5 years). To test the correlation between direct and 3D image measurements, 21 landmarks were labeled on the face of each subject. Sixteen direct measurements were obtained twice using digital calipers; the same measurements were then made on two sets of 3D facial images. The mean values of measurements obtained from both methods were compared. To investigate the precision, a comparison was made between two sets of measurements taken with each method. RESULTS: When comparing the variables from both methods, five of the 16 possible anthropometric variables were found to be significantly different. However, in 12 of the 16 cases, the mean difference was under 1 mm. The average value of the differences for all variables was 0.75 mm. Precision was high in both methods, with error magnitudes under 0.5 mm. CONCLUSIONS: 3D scanning images have high levels of precision and fairly good congruence with traditional anthropometry methods, with mean differences of less than 1 mm. 3D surface imaging using the Morpheus 3D(R) scanner is therefore a clinically acceptable method of recording facial integumental data.

Three-dimensional assessment of upper lip positional changes according to simulated maxillary anterior tooth movements by white light scanning / 대한치과교정학회지

OBJECTIVE: Esthetic improvements during orthodontic treatment are achieved by changes in positions of the lips and surrounding soft tissues. Facial soft-tissue movement has already been two-dimensionally evaluated by cephalometry. In this study, we aimed to three-dimensionally assess positional changes of the adult upper lip according to simulated maxillary anterior tooth movements by white light scanning. METHODS: We measured changes in three-dimensional coordinates of labial landmarks in relation to maxillary incisor movements of normal adults simulated with films of varying thickness by using a white light scanner. RESULTS: With increasing protraction, the upper lip moved forward and significantly upward. Labial movement was limited by the surrounding soft tissues. The extent of movement above the vermilion border was slightly less than half that of the teeth, showing strong correlation. Most changes were concentrated in the depression above the upper vermilion border. Labial movement toward the nose was reduced significantly. CONCLUSIONS: After adequately controlling several variables and using white light scanning with high reproducibility and accuracy, the coefficient of determination showed moderate values (0.40-0.77) and significant changes could be determined. This method would be useful to predict soft-tissue positional changes according to tooth movements.

Micro-computed tomography analysis of changes in the periodontal ligament and alveolar bone proper induced by occlusal hypofunction of rat molars / 대한치과교정학회지

OBJECTIVE: To three-dimensionally elucidate the effects of occlusal hypofunction on the periodontal ligament and alveolar bone proper of rat molars by micro-computed tomography (micro-CT). METHODS: Occlusal function in the molar area was restricted by attaching an anterior bite plate on the maxillary incisors and a metal cap on the mandibular incisors of 5-week-old male Wistar rats for 1 week. The periodontal ligament space and alveolar bone proper around roots of the mandibular first molar were assessed by histology and micro-CT. RESULTS: The periodontal ligament space was narrower and the alveolar bone proper was sparser and less continuous in the hypofunction group than in the control group. Further, both the volume of the periodontal ligament and the volumetric ratio of the alveolar bone proper to the total tissue in the region of interest were significantly lower in the hypofunction group (p < 0.05). CONCLUSIONS: Occlusal hypofunction induces atrophic changes in the periodontal ligament and alveolar bone proper of rat molars.

Three dimensional analysis of Korean dentogingival complex / 대한치주과학회지

PURPOSE: Variation in the morphology of gingival papilla may be determined by the shape and position of anatomic crown as well as contact area and embrasure form of individual teeth. However, periodontal biotype classification is regarded to be subjective because of the lack of definite criteria. In this study, we defined the objective parameters which constitute the periodontal biotype and measured their relationship. MATERIALS AND METHODS: 109 of dental casts were prepared using three dimensional scanner and specialized reconstruction software, then acquiredvirtual models were sent to the 20 professional dentists to define the specific periodontal biotypes. Several parameters around periodontal structures were measured from the virtual models; facial surface area of the anterior tooth (AT), anterior papillary area (AP), proportion of the dento-papillary complex, clinical papillary length (PL), and clinical papillary angle (PA). Statistical analysis was performed to confirm the relationship among parameters. RESULTS: Coincidence rate of periodontal biotype within observers was 63.77+/-16.05%. Coincidence rate between observers was 76.15+/-16.43%. Among the parameters measured, PL showed the most positive correlations and PA presented the most negative correlations. The parameter of the AP and PL of six maxillary anterior teeth showed significant correlation coefficient. CONCLUSION: Anterior papillary area and clinical papillary length would be objective parameters for determining the consistent periodontal biotypes.