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.

Three-dimensional radiographic assessment of the mandibular retromolar donor site in different vertical facial growth types.

PURPOSE: To assess volumetrically, the impact of vertical facial growth types (VGFT) on the retromolar area as a bone donor site MATERIAL AND METHODS: 60 cone beam computed tomography (CBCT) scans of adult individuals were classified in three groups according to their SN-GoGn angle: hypodivergent group (hG) (33.33%), normodivergent group (NG) (30%) and hyperdivergent group (HG) (36.67%). Total harvestable bone volume and surface (TBV and TBS respectively), total cortical and cancellous bone volume (TCBV and TcBV respectively) and the percentage of cortical and cancellous bone volume (CBV and cBV respectively) were evaluated. RESULTS: The whole sample showed a mean TBV of 1220.99±448.81mm³ and a mean TBS of 940.29±259.93mm². Statistically significant differences were found between the different outcome variables and the vertical growth patterns (p<0.001). TBS differs for the different vertical growth patterns with the highest mean of TBS observed in the hG group. TBV also significantly differs between the different vertical growth patterns (p<0.001) with the highest mean observed for the hG individuals. Significant differences in percentages of cBV and CBV were present between the hyper-divergent groups and the other groups (p<0.001) with the hyper-divergent group having the lowest percentage of CBV and the highest percentage of cBV. CONCLUSION: hypodivergent individuals tend to have thicker bone blocks that can be used in onlay technique while thinner bone blocks harvested from hyperdivergent and normodivergent individuals can be used in three-dimensional grafting approach.

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.

Assessment of lower third molar space: A comparative radiographic study.

OBJECTIVE: The aim of this study was to assess lower third molar space using four different radiographic reconstructed Cone Beam Computed Tomography (CBCT) images: orthopantomogram, lateral cephalogram, multiplanar CBCT and a newly introduced three-dimensional (3D) simulation technique. METHODS: The CBCT scans of 32 individuals (20.97 ± 2.152 years) with a total of 50 lower third molars were collected and analyzed. The ratio between the necessary space and available space for lower third molars was calculated on each radiographic reconstructed image. Repeated-measure analysis of variance followed by multiple comparison tests were used. RESULTS: The mean ratio was significantly smaller with cephalograms (0.611 ± 0.263), followed respectively by orthopantomograms (0.756 ± 0.221), multiplanar CBCT (0.789 ± 0.191) and 3D simulation technique (0.807 ± 0.193) (p < 0.001). The lowest mean difference was recorded between multiplanar CBCT and 3D simulation technique (0.017). Intraclass correlation coefficient was strong (>0.90) for all techniques except cephalograms. CONCLUSIONS: The assessment of the lower third molar space differs according to the adopted imaging technique. Three-dimensional simulation technique is a useful novel technology that allows an exploration of the crown in many different dimensions and orientations, giving more predictable results than the conventional methods.

Correlation of Vertical Dentoalveolar Heights with Palatal Plane Inclination in Adults with Different Vertical Facial Patterns / Corrélation des hauteurs dento-alvéolaires verticales avec l'inclinaison du plan palatin chez les adultes présentant différentes typologies faciales verticales

Introduction: Various studies showed inconsistent and different results regarding the correlation between open bites and palate planes whether normal or abnormal. This study had for objective to investigate the correlation between dentoalveolar heights and palatal plane inclination in different vertical facial patterns. Materials and Methods: 120 lateral cephalometric radiographs (60 females and 60 males) were selected from the archives of the Faculty of Dentistry, Beirut Arab University. The sample consisted of three equal groups: hypodivergent (SN/MP<27°), normodivergent (SN/MP=27°-37°) and hyperdivergent (SN/MP>37°). The radiographs were digitally traced and cephalometric skeletal and dentoalveolar variables were measured. Statistical analysis was carried out with significance level at p<0.05. Results: The palatal plane inclination showed statistically significant difference between hyperdivergent and both hypodivergent and normodivergent subjects with no statistically significant difference between hypodivergent and normodivergent subjects. A statistically significant difference in the upper anterior dentoalveolar height (UADAH) was found between hypodivergent and both hyperdivergent and normodivergent subjects. No statistically significant difference was found in the other dentoalveolar heights between the different vertical patterns. A negative moderate correlation was only observed between the palatal plane angle and UADAH in the hyperdivergent group. Multiregression analysis showed that the greatest contribution to overbite pooled across all groups other than the skeletal pattern was attributed to UADAH. Conclusion: UADAH seems to influence the overbite depth compared to other dentoalveolar heights. It is possible that UADAH acts as a compensatory factor for palatal plane inclination in hyperdivergent subjects.

Introduction: Diverses études ont montré des résultats incohérents et différents concernant la corrélation entre les béances et les plans du palais, qu'ils soient normaux ou anormaux. Cette étude avait pour objectif d'analyser la corrélation entre les hauteurs dento-alvéolaires et l'inclinaison du plan palatin dans différentes typologies faciales verticales. Matériels et méthodes: Au total, 120 radiographies céphalométriques latérales (60 femmes et 60 hommes) ont été sélectionnées dans les archives de la Faculté de médecine dentaire de l'Université Arabe de Beyrouth. L'échantillon était composé de trois groupes égaux : hypodivergent (SN/PM < 27°), normodivergent (SN/PM = 27° - 37°) et hyperdivergent (SN/PM > 37°). Les radiographies ont été tracées numériquement et les variables squelettiques et dento-alvéolaires céphalométriques ont été mesurées. L'analyse statistique a été réalisée avec un seuil de signification à p < 0,05. Résultats: L'inclinaison du plan palatin a montré une différence statistiquement significative entre les sujets hyperdivergents et les sujets hypodivergents et normodivergents, sans différence statistiquement significative entre les sujets hypodivergents et normodivergents. Une différence statistiquement significative dans la hauteur dento-alvéolaire antérieure supérieure (HDAAS) a été trouvée entre les sujets hypodivergents et les sujets hyperdivergents et normodivergents. Aucune différence statistiquement significative n'a été trouvée dans les autres hauteurs dento-alvéolaires entre les différents modèles verticaux. Une corrélation négative modérée n'a été observée qu'entre l'angle du plan palatin et la HDAAS dans le groupe hyperdivergent. L'analyse multirégression a montré que la plus grande contribution à la supraclusion regroupée dans tous les groupes autres que le schéma squelettique était attribuée à la HDAAS. Conclusion: La HDAAS semble influencer la profondeur de supraclusion par rapport aux autres hauteurs dento-alvéolaires. Il est possible que celle-ci agisse comme un facteur compensateur de l'inclinaison du plan palatin chez les sujets hyperdivergents.

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.

Evaluation of shear bond strength of orthodontic molar tubes bonded using hydrophilic primers: An in vitro study.

OBJECTIVE: To evaluate and compare the shear bond strength (SBS) of orthodontic molar tubes bonded using two hydrophilic primers along with a moisture tolerant adhesive system to dry and saliva-contaminated enamel surfaces; and to assess the mode of their bond failure. MATERIALS AND METHODS: A total of 60 extracted human mandibular molars were randomly divided into three major groups according to the primer used, each consisting of 20 molars: XT group acts as a control and bonded with the conventional hydrophobic Transbond XT primer, OS group bonded with the hydrophilic Ortho Solo primer, AP group bonded with the hydrophilic Assure Plus all surface bonding resin. Each major group was further divided into two subgroups, of 10 molars each, according to presence or absence of saliva. All the specimens were thermocycled 500 cycles between 5̊ and 55°C. Shear forces were applied to the specimens with a universal testing machine at a crosshead speed of 1mm/min and SBS was measured in megapascals (MPa). The mode of failure was determined using the adhesive remnant index (ARI). Data were analysed using two-way analysis of variance (ANOVA) followed by univariate analysis and Bonferroni post hoc tests. RESULTS: The three tested primers did not show a significant difference in the mean SBS in dry conditions (P=0.137); the mean SBS of OS and AP primers were 15.60±5.879MPa and 12.51±2.583MPa respectively which were comparable to that of the hydrophobic XT primer (12.76±2.952MPa). In saliva-contaminated conditions, the mean SBS values were 10.41±4.457MPa and 9.22±3.422MPa for OS and AP primers respectively, which were significantly higher than that of XT primer (4.82±2.050MPa) (P=0.004). When comparing the mean SBS for each group according to the bonding condition, it was significantly higher in dry bonding compared to saliva-contaminated bonding for the three primers; XT (P<0.001), OS (P=0.003) and AP (P=0.011). In the dry field, most of the bond failures of the three primers were adhesive (score 3), whereas in the saliva-contaminated field, most of the failures were cohesive (score 1). CONCLUSION: Dry bonding yielded the highest SBS for the three primers. Saliva contamination significantly decreased the bond strength of both hydrophilic primers; however, the values were above the clinically acceptable limit. The hydrophilic primers tested in the present study can be successfully used for bonding orthodontic molar tubes under dry and saliva-contaminated enamel surface conditions.

The inflection point: a torque reference for lingual bracket positioning on the palatal surface curvature of the maxillary central incisor.

BACKGROUND: Contrary to buccal orthodontics, lingual orthodontics has no reference for vertical bracket positioning on the maxillary central incisor. The aim of this study was to provide a reference point in relation to torque for lingual bracket positioning on the palatal surface curvature (PSC) of the maxillary central incisor. METHODS: Cone beam computed tomography (CBCT) radiographs of 50 right maxillary central incisors from archives of a dental radiographic center were transferred to Photoshop, where their PSC was traced using pen-tool. The PSC torque angle values of the incisors were calculated in Excel using cubic poly-Bezier curves at 0.5-mm increments and at the inflection point of PSC. Descriptive statistics for the torque angle values of the increments and for the inflection point for the 50 incisors were then calculated. One-way ANOVA test was used to detect systematic differences between the increments, and Tukey test was used post-hoc. RESULTS: For all incisors, increments incisal to inflection point exhibited progressive decrease in torque angle values from the first-calculated increment to inflection point while increments cervical to inflection point exhibited progressive increase from inflection point to last-calculated increment. Mean torque angle values of all the increments and inflection point showed high standard deviations and vast range of values. One-way ANOVA test was highly statistically significant (p < 0.0001) and most pairwise comparisons of the increments using Tukey test were significant. CONCLUSIONS: Inflection point can be used as a reference for bracket positioning on PSC. Cervically oriented shifts in vertical bracket position cause crown labial/root palatal movement cervical to inflection point and crown palatal/root labial movement incisal to it. A scientific mathematical justification for customized bracket torque prescriptions on PSC of maxillary central incisor was also provided.

Anterior teeth root inclination prediction derived from digital models: A comparative study of plaster study casts and CBCT images.

BACKGROUND: To assess the accuracy of digital models generated using commercially available software to predict anterior teeth root inclination characteristics and compare the results to relevant data obtained from CBCT images. MATERIAL AND METHODS: Following sample size calculation and after application of inclusion and exclusion criteria, pre-treatment maxillary and mandibular plaster models and the corresponding CBCT scans of 31 patients attending a private orthodontic clinic were selected. The subjects were 10 males and 21 females with age range 12 to 40 years. Plaster models were scanned using the high resolution mode of an Ortho Insight 3D scanner and CBCT scans were taken using a Kodak 9500 Cone Beam 3D System machine. The teeth on the digital scans were segmented and virtual roots were predicted and constructed by the Ortho Insight 3D software. The long axes of the predicted roots and the actual roots, as segmented from the CBCT images, were computed using best-fit lines. The inter-axis angle was used to assess error in root inclination prediction by the software. Mann-Whitney and Kruskal-Wallis tests were used. Intra-examiner error was evaluated using the Bland-Altman method. RESULTS: The maximum disparity in angle between images derived from digital models and CBCT data was almost 40 degrees (upper left canine). The upper and lower canines produced the worst results, followed by the lower lateral incisors. The upper central incisors showed the best results, although the maximum angle of difference exceeded 20 degrees (with the median around 8 degrees). CONCLUSIONS: Root morphology imaging prediction is not a primary function of this software and this study confirmed its limitation as a sole tool in routine clinical applications. At present these predictions cannot be considered accurate or reliable unless correlated clinically with a radiographic image. Key words:Digital models, CBCT, tooth root inclination prediction software.

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.

Assessment of the efficiency of Erbium-YAG laser as an assistant method to rapid maxillary expansion: An in vivo study.

INTRODUCTION: Maxillary transverse deficiency (MTD) is one of the most pervasive and common skeletal problems in the craniofacial complex. This study aimed to evaluate the effect of associating the application of Erbium-YAG laser with rapid maxillary expansion (RME) for treating MTD in young adult patients with permanent dentition in regard to skeletal and dental effects. METHODS: Twenty-four subjects, aged from 15.5 to 19 years and needing RME as a therapeutic procedure, were randomly assigned to either the laser group (n=12) or the control group (n=12). The RME was realized by a two bands hyrax expander cemented on upper first molars. Patients in the laser group were undergone mucosal-bony perforations along the midpalatal suture every month, for three consecutive months, using Erbium-YAG laser. Postero-anterior cephalograms were taken for all patients. Skeletal and dental changes before and after RPE as well as at the end of the retention phase were collected and compared for both groups. Total time needed for expansion and retention were recorded and compared. RESULTS: The findings showed more significant changes in most maxillofacial components in the laser group after the expansion phase. However, there was no significant differences with respect to retention or total treatment duration. CONCLUSIONS: Laser assisted rapid maxillary expansion (LARME) can be a good approach to use for improving skeletal effects in young adult patients suffering from MTD.

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.