Multinational study on profile preference of laypersons.

BACKGROUND: This study aimed to assess the facial profile preferences of lay people in seven locations from different countries and whether their place of residence, sex, age, race, education, or income influenced the decision. METHODS: After altering the lip and nose in 1 mm increments in the sagittal and sagittal/vertical directions, 50 profile silhouettes with white-like facial features were rated by evaluators. The soft tissue values were integrated into the profiles, and profile preferences were identified for each location. An ANOVA with post hoc Tukey test was used to compare the differences in mean preference in each location. A multivariable regression model was used to assess the effect of the demographics of the evaluator on preference. RESULTS: Thirteen profiles were ultimately analyzed. The mean for profile preference was significantly different across locations (P < 0.0001). For evaluators in the United States and Lebanon, the most preferred profile had the original lip and original nose. In Switzerland and South Africa, retrusive lips, and a small and less upturned nose was most preferred. In Japan and Saudi Arabia, the most preferred profile had the original lip and a protrusive nose that was less upturned. A protrusive lip with a small, upturned nose was preferred in Turkey. Profile change (P < 0.0001), location (P < 0.0001), sex (P < 0.0001), and race (P = 0.02) were significant confounders; in contrast, age, education, and income were not significant. CONCLUSIONS: Profile preference is different among the seven locations. For the most part, lay people prefer profiles within one SD from white norms. Also, an upturned nose is the least favored in most of the locations. Sex and race are also significant confounders. CLINICAL RELEVANCE: An orthodontic treatment plan decision is affected by an individual's preference for their facial appearance. This study helps clinicians understand how racial and regional differences may affect patients' preferences and, therefore, their expectations for orthodontic treatment results.

Effect of head rotation on two-dimensional cephalometric measurements using cone beam-computed tomography.

OBJECTIVE: The purpose of this study was to identify the variation of bi-dimensional cephalometric measurements following real head rotation. MATERIAL AND METHODS: Thirty cone beam-computed tomography (CBCT) head films were oriented according to three axes: horizontal Frankfort plane, transverse bi-orbital plane, and Opisthion-Nasion median plane. Axial rotation of 2°, 4°, 6°, and 8° from the Odontoïdale point were performed. Horizontal and vertical linear and angular measurements were studied on lateral cephalograms derived from each rotation T0, T2, T4, T6, and T8. A paired t-test was applied to compare the measurements between T0 and each rotational angle. RESULTS: Of the 18 measurements, 55% showed statistically significant differences (P < 0.05) and 22% showed clinically significant differences, mostly at T6 and T8. Horizontal linear measurements Ba-A and N-Ba decreased, and vertical linear measurement G-Sn increased gradually, as the angle of head rotation increased. Angular measurements studied did not vary. CONCLUSIONS: Head malpositions during X-ray acquisition should be avoided and rotated lateral CBCT cephalograms should be corrected and recentered to prevent any variation in linear measurements.

Assessment of infrazygomatic crest dimensions in different vertical facial growth types for miniscrew insertion: A cone-beam computed tomography study.

INTRODUCTION: This study aimed to assess the depth and height of the infrazygomatic crest (IZC) located in the posterior maxilla at the junction with the zygomatic process in patients with different vertical facial growth types as a potential miniscrew insertion site. METHODS: The sample consisted of cone-beam computed tomography scans of 117 patients (42 males and 75 females), with a mean age of 22.9 ± 2.7. The population was divided into 3 groups according to the measured SN-GoGn angle: Decreased facial proportions (n = 28), average facial proportions (n = 62), and increased facial proportions (n = 27). Bone depth was assessed at 5 levels: apex, 1, 2, 3, and 4 mm vertically from the apex. The measurements were performed on the mesiobuccal and distobuccal roots of the first molar and the mesiobuccal root of the second molar. Repeated-measure analysis of variance followed by univariates analyses and Bonferroni multiple comparisons were performed to compare the mean bone thickness between groups. The IZC height was assessed through a vertical line ranging from the furcation of the maxillary first molar to the sinus floor. Analysis of variance followed by Tukey (honestly significant difference) post-hoc tests was used to compare the mean height between groups. RESULTS: Mean bone depth between the 3 groups were significantly different at the mesiobuccal root region of the first molar at all the measured levels. It was smaller for average, intermediate for decreased, and elevated for increased facial proportions. No statistical difference was shown at the distobuccal root of the first molar except for the apex level and the mesiobuccal root of the second molar except for the apex and 4 mm levels. The mean bone height was significantly different between subjects with increased facial proportions and the 2 other groups. CONCLUSIONS: Subjects with increased facial proportions tend to present a longer and deeper IZC followed by decreased facial proportions, then average facial proportions.

Evaluation of upper airway volume and craniofacial volumetric structures in obstructive sleep apnoea adults: A descriptive CBCT study.

OBJECTIVE: The aim of this investigation was to assess, with a descriptive three-dimensional evaluation, the volume of upper airway (UAWV) and the volume of craniofacial structures in adult patients suffering from obstructive sleep apnoea (OSA) and compare them to the corresponding findings in adults with no sleep disorders. MATERIALS AND METHODS: The sample consisted of 54 adult males, 27 suffering from OSA diagnosed by means of the Apnoea Hypopnea Index and 27 with no history of sleep disorders. All subjects had a cone beam computerized tomography scan performed with the same head position. UAWV was assessed with the Amira® software, and craniofacial volumes by means of a specially developed data-processing program, which allowed the construction of tetrahedrons using anatomical landmarks. Assessed volumes were naso-maxillary, cranium upper anterior, oral cavity, post-oral cavity, hyoid to mandible, and post-hyoid. SPSS (version 19.0) was used for the statistical analysis. The Levene's test for Equality of Variance, the t-test for Equality of Means and the Mann-Whitney test were used to evaluate the variables. The level of significance was set at P ≤ 0.05. RESULTS: The mean value of UAWV was smaller in the OSA group. The post-hyoid volume, the calculated posterior volume, and the ratio of posterior to total volume showed differences between the groups. CONCLUSIONS: Craniofacial structures did not show significant differences between the groups, but in the OSA group the posterior space released for upper airway was significantly bigger and UAWV was significantly smaller.

Maxillary and mandibular contribution to the establishment of class II malocclusion in an adult Lebanese population.

INTRODUCTION: The main aim of this study was to describe the contribution of the maxilla and the mandible to the establishment of a Class II skeletal malocclusion in an adult Lebanese population. Secondary aims were to detect the presence of sex-based dimorphism and to study the influence of the vertical dimension on the Class II skeletal pattern. MATERIAL AND METHOD: A sample of 90 adults in skeletal Class II was recruited and equally distributed according to sex and vertical typology. The study describes the skeletal and dentoalveolar cephalometric characteristics of the Class II sample, essentially according to Coben's cephalometric analysis. RESULTS: The total effective depth of the cranial base and the anterior cranial base angle (SN-BaH) were both greater in the Class II sample. In females, the effective depth of the maxilla (Ptm-A) was larger than normal while SNB was smaller. The parameters describing the size and shape of the body of the mandible were significantly different from those of normal subjects. The upper incisors were in a retrusive position, while the axis of the lower incisors was located normally. The mandibular molars had a more distal sagittal position. Hyperdivergent subjects had more significant posterior alveolar growth, a more retrusive mandibular position and smaller mandibular dimensions than the other two vertical sub-groups. CONCLUSION: The cranial base contributes to the establishment of a Class II malocclusion, and mandibular retrusion cannot be considered as a characteristic shared by all skeletal Class II subjects. Lessening of the absolute length of the mandibular body is the second most frequent etiological factor noted in the Class II sample studied. Most individuals in skeletal Class II have an associated dental Class II malocclusion, and the vertical dimension has an influence on the Class II skeletal pattern.

Skeletal and dento-alveolar norms: Conventional and based on true vertical in a Lebanese population.

OBJECTIVE: The aims of this study were to determine the cephalometric norms in a Lebanese population of young adults, to find the differences in cranio-facial morphology between males and females and to establish the equivalency between conventional measurements and those based on the true horizontal. MATERIALS AND METHOD: Ninety subjects divided into 43 women and 47 men, aged from 18 to 30years, were selected based on specific criteria. The lateral cephalograms were taken in the natural head position. Downs, Steiner, Tweed, Ricketts, Epker and Fish, Coben, McNamara and Jacobson analyses were applied by orienting radiographs according to the Frankfurt anatomic plane, and Scheideman, Cooke, Arnett, and Viazis analyses were performed by orienting the radiographs according to the true vertical. RESULTS AND CONCLUSION: The specific skeletal and dento-alveolar measurements from this sample are reported in nine grids. Differences between males and females were found especially at the B and Pog points, which were more posterior in men, who also presented a greater lower facial height in relation to total facial height. Women had more protrusive upper incisors when measured in the maxillary plane.

Soft tissue norms: Conventional and based on true vertical in a Lebanese population.

INTRODUCTION: The aim of this study was to establish cephalometric soft tissue norms in a Lebanese population of young adults and profile differences between males and females. MATERIALS AND METHODS: Ninety subjects divided into 43 women and 47 men, aged from 18 to 30 years, were selected based on specific criteria. The lateral cephalograms were taken in the natural head position. Holdaway, Steiner, Merrifield, Ricketts, Epker and Fish analyses were applied as conventional analyses. Scheideman, Spradley, Cooke, Arnett, Bergman, Farkas and Viazis analyses were applied as analyses based on the true vertical. RESULTS AND CONCLUSION: The specific soft tissue measurements of this sample are reported in six grids. The differences between males and females related especially to the lower facial height and lip thickness, which had higher values in males, who also presented a more retruded lower lip and more protruded nasal tip. Women had higher values for mentolabial and frontonasal angles.

The importance of using the entire face to assess facial profile attractiveness.

INTRODUCTION: The aim of this study was to evaluate the importance of using the entire face to assess facial profile attractiveness. The secondary objective was to assess the facial profile preferences of orthodontists, dentists and laypeople. METHODS: Two original cephalometric radiographs of two subjects (one man and one woman meeting the normality criteria) and 16 modified samples of these radiographs were used. The 18 radiographs were then converted into silhouettes and printed twice: the entire profile (A) and the lower third alone (B). The silhouettes were randomly distributed into two binders A and B. A survey was conducted using three panels of evaluators: orthodontists, dentists and laypeople. The esthetic appreciation was quantified according to the Visual Analogue Scale (VAS). RESULTS: Pearson's correlation coefficient was calculated to compare the scores of the entire profile with the scores of the lower third alone. The results showed that the orthodontists panel presented a much better correlation between A and B compared to dentists and especially to laypeople. A comparison of profile scores with the correlation coefficients shows that the profiles with the highest scores present the lowest correlations. The three panels of evaluators preferred the orthogonal profiles or profiles with upper lip protrusion over profiles with lower lip protrusion. CONCLUSION: For profiles with values close to the norm, the lower face alone does not reveal the attractiveness of the entire facial profile. Hence, the importance of using the entire facial profile to assess the beauty of the face.

Three-dimensional changes of the naso-maxillary complex following rapid maxillary expansion.

OBJECTIVE: To assess the volumetric changes and the maxillary response of the naso-maxillary complex (NMC) following rapid maxillary expansion (RME). MATERIALS AND METHODS: Thirty consecutive patients (14 males and 16 females) with a mean age at first observation of 9.5 ± 1.8 years for males and of 11.8 ± 1.7 years for females, presenting a posterior unilateral or bilateral crossbite and requiring RME, were selected for the study. Each patient underwent expansion to correct the transverse occlusal relationships. Computed tomography scans were taken before RME (T1) and at the end of the active expansion phase (T2). Measurements were performed on scanned images. The Kolmogorov-Smirnov test was performed; the mean differences between measurements at T1 and T2 were compared using the t-test (α = .05). RESULTS: All volumetric, maxillary, transverse skeletal anterior and posterior variables as well as all dental anterior and posterior linear and angular variables representing the NMC displayed statistically highly significant increases after RME (P < .001). CONCLUSIONS: After RME the total volume of the NMC increased by 12%, the nasal volume by 17%, and the maxillary volume by 10.6%. The maxillary and the nasal contributions represented 69.75% and 30.25%, respectively.

Effects of buccal and lingual enamel sandblasting on shear bond strength of orthodontic brackets bonded with a self-etching primer.

The purpose of this study was to evaluate the effects of sandblasting on the initial shear bond strength (SBS) and on the bracket/adhesive failure mode of orthodontic brackets bonded on buccal and lingual enamel using a self-etching primer (SEP). The brackets were bonded using a SEP and composite resin on the buccal and lingual surfaces of 30 premolars with intact enamel and 30 premolars pretreated by sandblasting with 50 µm aluminum-oxide. Student's paired t-test was used to compare the groups for differences in SBS and a multiple Chi(2) test was performed to compare the bond failure mode. It was shown that sandblasting increases significantly SBS of the SEP on the buccal surfaces but the increase on the lingual surfaces is not statistically significant. A comparison of the adhesive remnant index scores indicated that there was more residual adhesive remaining on the teeth that were treated by sandblasting than on the teeth with intact enamel. Besides, there is no statistical difference between SBS of the SEP on buccal and lingual surfaces with intact enamel. Therefore, we can conclude that sandblasting improves the bond between buccal and lingual enamel and resin ant that the SEP provides the same SBS on buccal and lingual intact surfaces.

Effect of a two-year fluoride decay protection protocol on titanium brackets.

INTRODUCTION: Fluoride ion can attack titanium, causing its corrosion. Orthodontic patients being high-risk caries developers and in need of fluoride protection, the Center for Disease Control has developed a Fluoride Decay Prevention (FDP) protocol, consisting of a 6-minute tooth-brushing, followed by a 1-minute daily mouthwash, in addition to an in-clinic trimestrial topical fluoride gel application. This study aimed at evaluating gravimetrically, by scanning electron microscopy (SEM), and by sliding mechanics analysis, the consequences of FDP at 6, 12, 18, and 24months on titanium brackets corrosion. METHODS: One hundred and fifty titanium brackets were randomly divided into five groups of 30. Group 1 was the control group. Groups 2, 3, 4, and 5 each received an equivalent of 6, 12, 18, and 24months of FDP treatment respectively. All groups were placed in artificial saliva for 2months and then rinsed. Subsequently, the brackets were dried, for 48hours, using Silica gel in a desiccator maintained at 37°C before testing. RESULTS: SEM analysis showed that numbers and dimensions of pits gradually increased due to corrosion as we moved from group 1 to group 5. Gravimetrical and sliding mechanics results revealed no statistical difference between groups 2 and 3, and a significant difference between groups 4 and 5 upon comparison with the control group. CONCLUSION: Surface changes due to corrosion were detected at 6 and 12months of FDP but had no clinical effects. However, the increase in sliding resistance and bracket weight loss became significant at 18 and 24months of FDP.

Effect of eliminating the residual fluoride gel on titanium bracket corrosion.

INTRODUCTION: Fluoride ions, in long-term applications on titanium brackets, cause their corrosion. Fluoride gel used for caries prevention during orthodontic treatment has a very high concentration in fluoride ions, and therefore has the potential for causing bracket corrosion. The main aim of this study was to determine the effect of eliminating the residual fluoride gel, by rinsing it, on the corrosion of titanium brackets. The secondary aim was to evaluate the corrosion of titanium brackets in the presence of fluoride gel. METHODS: One hundred titanium brackets were divided into five groups of 20 brackets each. Group 1 being the control group, the rest of the groups were immersed in fluoride gel: Group 2 for 4 minutes and kept for 30 minutes with the residual fluoride gel on; Group 3 for 4 minutes followed by immediate water rinsing; Group 4 for 12 minutes and kept for 90 minutes with the residual fluoride gel on and Group 5 for 12 minutes followed by immediate water rinsing. All groups were rinsed then dried, for 20 hours, using Silica gel in a desiccator maintained at 37°C before testing. RESULTS: Gravimetrical results and SEM analysis showed no significant difference between Groups 2, 3 and 5 compared to each other and to the control group. Only Group 4 showed significant weight loss and pitting corrosion in four of the 20 brackets. In sliding resistance, no significant difference was detected between any of the groups. CONCLUSIONS: Short time applications of fluoride gel do not affect sliding resistance of titanium brackets. No titanium corrosion was detected for one application of concentrated fluoride gel and some brackets showed pitting corrosion for three applications. The rinsing of residual fluoride gel eliminates completely the risk of bracket corrosion.

[Sexual dimorphism and facial cavities: a 3D imaging volumetric study]. / Dimorphisme sexuel et cavités faciales: étude volumétrique en imagerie 3D.

INTRODUCTION: The aim of this study was to investigate the sexual dimorphism in facial cavity's volumes of untreated young adults. METHODS: Sixty subjects, ages between 18 to 30 years, were selected and divided in two groups according to the gender. Volumes of orbital, nasal, sinusal and buccal cavities were measured from CT scans with AMIRA(®)software. The statistical studies were performed using Kolmogorov-Smirnov test for normality followed by Student "t" test (p < 0.05). RESULTS: The gender comparison reflected statistically significant differences between the volumes of orbital, nasal, sinusal and buccal cavities, volumes being larger in males. Sexual dimorphism did not appear in the ratio of each cavity volume on the total facial volume. CONCLUSION: Absolute volume of facial cavities are larger in males, but no sexual dimorphism is detected comparing volume ratios. A difference in size, but not in shape, between genders might exist.

Aesthetic evaluation of profile incisor inclination.

The objectives of this study were to evaluate (1) the impact of maxillary incisor inclination on the aesthetics of the profile view of a smile, (2) to determine the most aesthetic inclination in the profile view of a smile and correlate it with facial features, and (3) to determine if dentists, orthodontists, and laypeople appreciate differently incisor inclination in smile aesthetics. A smiling profile photograph of a female subject (22 years of age) who fulfilled the criteria of soft tissue normative values and a balanced smile was obtained. The photograph was manipulated to simulate six lingual and labial inclinations at 5 degree increments to a maximum of 15 degrees. The seven photographs were randomly distributed in a binder to three groups of raters (30 dentists, 30 orthodontists, and 30 laypeople) who scored the attractiveness of the photographic variations using a visual analogue scale. Comparison of the mean scores was carried out by repeated analysis of variance, univariate tests, and multiple Bonferroni comparisons. The results showed a statistically significant interaction between the rater's profession and the aesthetic preference of incisor inclination (P = 0.013). The profile smile corresponding to an increase of 5 degrees in a labial direction had the highest score among all professions and among male and female raters. Orthodontists preferred labial crown torque; dentists and laypeople did not appreciate excessive incisor inclination in either the lingual or the labial directions. The most preferred smile matched with a maxillary incisor inclined 93 degrees to the horizontal line and +7 degrees to the lower facial third.

[Facial volumes and vertical facial type: a three dimensional comparative study]. / Volumes faciaux et typologie verticale : étude comparative tridimensionnelle.

INTRODUCTION: The purpose of this study was to compare the volume of facial cavities in untreated young subjects with long- and short-faces. METHODS: Two groups of thirty subjects each, one with low (GoGn-SN < or = 28 degrees), and the other with high (GoGn-SN > or = 36 degrees) mandibular plane angles, ages between 18 to 30 years, were selected. For each subject, volumes of orbital, sinusal and buccal cavities were measured from CT scans with the AMIRA software. The statistical studies were performed using Kolmogorov-Smirnov, followed by Student "t" test (p < 0.05). RESULTS: Results suggest that there is no statistically significant difference between the volume of facial cavities in long- and short-face subjects. Only the ratio of nasal cavity volume to the total volume is significantly smaller in the short-face group. CONCLUSION: A compensatory phenomenon might exist between the three directions of growth to equilibrate an excess or deficit of the vertical dimension, thus maintaining constant the volume of facial cavities.