OBJECTIVES: This study aimed to analyze the correlations and proportional relationships between maxillary anterior teeth (MAT) and facial measurements in Han Chinese individuals with the most attractive smiles, as evaluated by dental professionals. METHODS: Ten dentists with more than 5 years of clinical experience from different professional directions in a tertiary stomatological hospital were selected to evaluate the smile attractiveness of volunteers by visual analogue scale (VAS). Eighty-eight Han volunteers with the most attractive smile were selected. The perceived width of the MAT, the dimensions (height and width) of the maxillary central incisors (MCI), and the facial dimensions (intercanthal distance, interzygomatic distance, interalar distance, facial height and lower facial height) of the volunteers were measured on the frontal photos of the smile, digital oral model, and 3D face model. Pearson correlation analysis was performed to analyze linear correlations, and regression analysis was carried out to explore the proportional relationships. Reliability analysis using the intraclass correlation coefficient verified the stability of these proportional relationships. In addition, the correlations between MAT perceived width and the proportional relationships of (MCI) height to width ratio, with facial dimensions were explored and their reliability was verified. RESULTS: In Han Chinese individuals with the most attractive smiles, as evaluated by dental professionals, the Pearson correlation coefficients among MAT perceived widths were 0.813, 0.389, and 0.560. A proportional relationship existed between the lateral incisor and central incisor, and the ratio was 0.729. No significant correlations were found between MCI and the inner canthal distance, zygomatic distance, interalar distance, facial height, or the lower one-third facial height except for a negative correlation (r=-0.357) between MCI height and facial height in males and a positive correlation (r=0.249) between MCI width and interalar width when genders were combined. CONCLUSIONS Correlations exist among MAT perceived widths in Han Chinese individuals with the most attractive smiles, as evaluated by dental professionals. Partial correlations are observed between MCI height and width and facial measurements. The perceived width of the lateral incisor can serve as a reference indicator for predicting the perceived width of the central incisor, providing a reference for the aesthetic restoration of MAT in the Han ethnicity population.
Adult ; Female ; Humans ; Male ; China ; Esthetics, Dental ; Face/anatomy & histology* ; Incisor/anatomy & histology* ; Maxilla/anatomy & histology* ; Smiling ; East Asian People

OBJECTIVE: To establish the Chinese Han national criteria for the thickness of upper lip in Chongqing and to investigate the effect of lip thickness on lip retraction in orthodontic treatment.
 METHODS: A total of 240 adult patients (male=120, female=120) of Chinese Han nationality aged 18-35 years in Chongqing were treated with cephalograms and measured the thickness of upper lip. We established the Chinese Han national criteria for the thickness of upper lip in Chongqing according to the results. Sixty-eight female patients with Angle II 1 from Department of Orthodontics Stomatological Hospital of Chongqing Medical University were treated with maxillary premolars extraction, and pre- and post-treated with lateral cephalograms, then divided into 3 groups according to our criteria: a thin lips group, a normal lips group and a thick lips group. The ratio of the incisors retraction and the upper lip retraction were measured and calculated. The correlation between incisors retraction and the upper lip retraction was analyzed by the Pearson correlation method.
 RESULTS: There was statistical significance in the thickness of upper lip between males and females (P<0.01). The ratio of maxillary inscior retraction to the upper lip soft tissue retraction was 1.6:1, 2.2:1 and 2.9:1 in the thin lips group, the normal lips group and the thick lips group, respectively.
 CONCLUSION Gender differences exist in the thickness of upper lip. Upper lip retraction with the incisors was negatively correlated with the soft tissue thickness of the upper lip in females with Angle II 1.
Adolescent ; Adult ; Bicuspid ; Cephalometry ; Female ; Humans ; Incisor ; Lip ; anatomy & histology ; Male ; Tooth Extraction ; Young Adult

OBJECTIVETo study the influence of nasolabial angle alteration on facial profile attractiveness and investigate the perception differences in profile attractiveness among laypeople.

METHODSA young Chinese female with normal hard and soft tissue cephalometric values was chosen as a research object. Profile photograph was taken in a natural head position. Photoshop software was chosen to rotate the nose tip and upper lip, thus changing the degree and direction of nasolabial angle. A total of 33 different profile pictures were achieved. Thirty-three professional orthodontists and 64 non-professionals were chosen to score these 33 pictures.

RESULTSWhen the upper lip position was fixed, the profile was considerably attractive because the angle of nasal tip was not changed or altered. When the nasal tip rotation angle was fixed, profiles with a retroclined upper lip were considered significantly attractive by the layperson and professional groups. Regardless of the direction of the nasal tip rotation, the respondents considered the profile with a retroclined upper lip highly attractive.

CONCLUSIONThe soft tissue profile with a retroclined upper lip looks considerably attractive in Chinese female populations. Therefore, during an orthodontic treatment, appropriate retraction of the incisor is recommended to improve soft tissue profile attractiveness.

Cephalometry ; Esthetics ; Face ; anatomy & histology ; Female ; Humans ; Incisor ; Lip ; Nose

OBJECTIVETo measure the effect of laser fluence and scanning velocity on ablation efficiency of enamel and dentin.

METHODSTwo extracted human incisors and two molars were cut transversely along the axial plane with a diamond saw to obtain dentin and enamel slices with thickness of about 1 mm. Samples were fixed on a motorized translation stage, the linear reciprocating movement in the plane perpendicular to the direction of laser incident was programmed by the controller, and the laser focused on the tooth surface, then 36 ablation lines on enamel and 48 ablation lines on dentin were produced. A femtosecond laser system with wavelength of 800 nm, pulse width 30 fs, repetition frequency 1000 Hz was used, and the diameter of the focused spot was approximately 25 µm. A group of different fluence (1.33, 1.77, 2.21, 4.42, 8.85, 17.69 J/cm(2) for enamel and 0.44, 0.66, 0.88, 1.33, 1.77, 2.21, 4.42, 6.63 J/cm(2) for dentin) and two scanning velocity (10 mm/s and 20 mm/s) were tested. Confocal laser scanning microscope was used to measure the ablation volume.Ablation efficiency for enamel and dentin was then calculated.

RESULTSUnder the fluence of 8.85 J/cm(2) there was the highest ablation efficiency for enamel, 18.703×10(-3) mm(3)/J (20 mm/s), and the highest ablation efficiency for dentin was found under the fluence of 2.21 J/cm(2), ie.223.458×10(-3) mm(3)/J (20 mm/s).

CONCLUSIONSFluence and scanning speed of this femtosecond laser can affect ablation efficiency for both enamel and dentin, and this suggests that with appropriate choice of fluence and scanning speed we can improve the ablation efficiency for enamel and dentin.

Dental Enamel ; radiation effects ; Dentin ; radiation effects ; Humans ; Incisor ; anatomy & histology ; Lasers ; Molar ; anatomy & histology

Typodont models of bilateral canines gingival displaced vertically for 3 mm and bilateral lateral incisors palatal displaced horizontally for 3 mm are made and every kind of the two kind models was divided into four groups: MDD, MBT, self-ligating and Tip-Edge. Each group of the two kinds of models had 5 models, so a total of 40 models for the two kinds of models were set up. The experimental models were aligned with a 0.30 mm of nickel titanium round wire in a water-bath with constant temperature 45 degrees C for 30 minutes. The three-dimensional digital images of the experimental models before and after the water bath were obtained by scanning with the three dimensional optical scanner ATOS. Geomagic software was used to overlap the digital images taken before and after the water bath treatment. The vertical changes of sign points of canines, the movements of sign points of lateral incisors in the sagittal plane and the horizontal plane were quantified by using the Color map. The data was then processed by a two-factor analysis of variance by using SAS 9.2 software package. Analysis of the results shows that the vertical changes of sign points of canines , the movements of sign points of lateral incisors in the sagittal plane and the horizontal plane of MDD group are all less than those in the other three groups, a statistically significant difference (P < 0.0001). And the size of the teeth displacement is directly related to the size of orthodontic force on the typodont models. Thus the preliminary results suggest that MDD appliance might have advantages of light force in the alignment stage, and that the possible relevant factors are the improvement of its sub-slot and the single ligation wing design.
Cuspid ; Dental Models ; Humans ; Imaging, Three-Dimensional ; methods ; Incisor ; anatomy & histology ; Malocclusion ; therapy ; Orthodontic Appliance Design ; Tooth Movement Techniques ; instrumentation ; methods

OBJECTIVETo evaluate Beijing college students' concern and preference for maxillary anterior tooth esthetic factors.

METHODSSeveral images about lip and tooth were made through computer. A questionnaire was sent out to students in ten colleges and then collected. There were five factors to be evaluated: relationship of maxillary incisors and lower lip, numbers of tooth exposed, shape of centric incisor, crown width-length ratio, gingival margin. Concern of the beauty of anterior tooth, ie. tooth shape, tooth arrangement, shape of gingiva and so on, were then analyzed.

RESULTSThere were 408 responses collected, and 47.5% (194/408) of them preferred light contact between upper incisors and lower lip; 49.5% (202/408) preferred 8 tooth exposed when smile; 69.1% (282/408) preferred oval crown shape; 52.5% (214/408) preferred 0.85 as a crown width-length ratio; 49.5% (202/408)of responses chose the curve of gingiva runs horizontal. The average score of concern for male was 52.6% (100/190), for female was 59.6% (130/218).

CONCLUSIONSMost results from this study accord with the classical principles of tooth esthetics. Sex affects the concern and preferences of maxillary anterior tooth esthetics factors.

Adult ; China ; Esthetics, Dental ; Female ; Gingiva ; anatomy & histology ; Humans ; Incisor ; anatomy & histology ; Lip ; anatomy & histology ; Male ; Maxilla ; anatomy & histology ; Odontometry ; methods ; Patient Preference ; Sex Factors ; Smiling ; Surveys and Questionnaires ; Tooth Crown ; anatomy & histology ; Young Adult

OBJECTIVETo analyze craniofacial growth three-dimensionally for adolescents with normal occlusion in Beijing.

METHODSOne hundred and twenty-six adolescents with normal occlusion were selected according to the criteria. The sample was divided into four age groups (53 within 4 years, 30 within 7 years, 27 within 10 years and 16 within 13 years). Information of growth was collected. Three-dimensional cephalometric system based on cone-bean CT was established.

RESULTSFrom 4 to 13 years Co-A increased (14.55 ± 1.15) mm on average on the left and (13.66 ± 1.14) mm on the right, and Co-Gn increased (22.89 ± 1.40) mm on the left and (22.82 ± 1.38) mm on the right; and U1-NA increased (2.20 ± 0.44) mm on the left and (1.60 ± 0.46) mm on the right; and CoL-CoR and GoL-GoR increased (13.31 ± 1.21) mm and (18.59 ± 1.40) mm, and N-Me increased (18.03 ± 1.32) mm.SN-PP and SN-MPL basically remained unchanged.

CONCLUSIONSAdolescents with normal occlusion in Beijing grew obviously in three-dimensions and developed harmoniously.

Adolescent ; Cephalometry ; methods ; Child ; Child, Preschool ; China ; Cone-Beam Computed Tomography ; Dental Occlusion ; Face ; anatomy & histology ; diagnostic imaging ; Facial Bones ; anatomy & histology ; diagnostic imaging ; growth & development ; Humans ; Imaging, Three-Dimensional ; Incisor ; anatomy & histology ; diagnostic imaging ; growth & development ; Mandible ; anatomy & histology ; diagnostic imaging ; growth & development ; Maxilla ; anatomy & histology ; diagnostic imaging ; growth & development ; Maxillofacial Development

OBJECTIVETo investigate the smile esthetic elements of Chinese Han-nationality female based on high definition (HD) digital camera with computer-image measuring technique.

METHODSHD digital camera was used to capture spontaneous smile process combined with computer-image measuring technique to establish the analysis method of smile. Ninety-nine Han-nationality female with normal gingiva, aged from 20 to 30 years were recruited. The lip-incisor edge distance, gingival display were measured. The data was statistically analyzed.

RESULTSA standard and objective method to analyze spontaneous smile was established. Forty-three percent (43/99) of the subjects studied were classified as having a high smile and average smile respectively, 13% (13/99) as having a low smile. Gingival display accounted for (1.34 ± 0.98) mm in high smile type.

CONCLUSIONSAverage smile and high smile type were most common in the Chinese Han-nationality female studied.

Adult ; Analysis of Variance ; Asian Continental Ancestry Group ; Cephalometry ; methods ; Esthetics, Dental ; Female ; Gingiva ; anatomy & histology ; Humans ; Image Processing, Computer-Assisted ; methods ; Incisor ; anatomy & histology ; Lip ; anatomy & histology ; Smiling ; Young Adult

OBJECTIVETo analyze and find factors affecting the height of adjacent gingival papilla of maxillary central incisor single implant in human in order to promote the esthetic result of dental implants.

METHODSSixteen maxillary central incisor single implants of 16 patients and 30 sites of adjacent tissues and prosthesis were evaluated. Data on the height of adjacent gingival papilla of dental implant and relative factors were obtained from clinical parameters, photographs, research models, and X radiographs.

RESULTSThe mean and standard deviation of adjacent gingival papilla height of maxillary central incisor single implant were (4.01 +/- 1.85) mm. Statistical analysis revealed that factors affecting the height of adjacent gingival papilla of implant were as following from strong to weak: vertical distance between contact point and gingival margin, vertical distance between proximal bone level of natural tooth and implant abutment, vertical distance between proximal bone level of natural tooth and contact point, proximal protruding degree of crown, horizontal distance between abutment and root, length ratio of the crown and fixture, vertical distance between proximal bone level of implant and abutment, lip-side protruding degree of crown, probing depth.

CONCLUSIONSMultiple factors affected the height of adjacent gingival papilla of maxillary central incisor single implant in human.

Adult ; Aged ; Dental Implants, Single-Tooth ; Esthetics, Dental ; Female ; Gingiva ; anatomy & histology ; Humans ; Incisor ; surgery ; Linear Models ; Male ; Maxilla ; surgery ; Middle Aged ; Young Adult

OBJECTIVETo investigate the dental compensation in different sagittal jaw relationships.

METHODSOne hundred and fifty-seven post-treatment cases with satisfied outcome were chosen. Computerized cephalometric analysis was performed to evaluate the sagittal jaw relationship. Incisor torque were measured based on study models. Correlation analysis was performed.

RESULTSCompared with skeletal class I cases, the upper incisors of skeletal class III cases were more proclined, and lower incisors were more retroclined; the opposite result was found in skeletal class II cases. Dental compensation in class I cases took place primarily at lower incisors.

CONCLUSIONSIncisor torque control was important in patients with various sagittal jaw relationships.

Cephalometry ; Female ; Humans ; Incisor ; Male ; Malocclusion ; therapy ; Mandible ; anatomy & histology ; Maxilla ; anatomy & histology ; Orthodontics, Corrective ; Torque