Discriminative thresholds of cephalometric indexes in the subjective evaluation of facial asymmetry

Evaluation of Soft Tissue Compensations in Subjects With Facial Asymmetry Using Cone Beam Computed Tomography (CBCT): A Retrospective Study

Introduction Facial asymmetry influences aesthetics and can involve either hard or soft tissues or both. Underlying skeletal asymmetry can be compensated by differential expression of soft tissue thickness on either side. Orthognathic surgical planning needs to take the interaction between the hard and soft tissues into account. The aim of this study was to assess the bilateral thickness of hard tissues and the corresponding facial soft tissue in asymmetric subjects to assess the compensation using cone beam computed tomography (CBCT) imaging. Materials and methods CBCT measurements of 30 skeletal Class l asymmetric untreated patients with menton deviation greater than 4 mm were included in the study. The side towards which the menton deviated was considered as the deviated side and taken as the control group (GC). The contralateral side of the menton deviation was considered as the non-deviated side and was taken as the test group (GT). The greatest width of both hard and soft tissues was measured at the head of the condyle; the centre of the ramal upper, middle, and lower thirds; furcation of the first molar; and apices of the first premolar and canine. Each landmark was precisely positioned on all three planes and the measurements were correlated. An independent t-test compared the difference of both hard and soft tissues between deviated and non-deviated sides. The correlation between the hard and soft tissues of both non-deviated and deviated sides was performed using the Pearson correlation two-tailed test. Results In the condylar and mid ramal regions, significant differences between the hard and soft tissues were noted in the GT (p < 0.05). In the non-deviated side, at the condylar region, it was noted that with an increase in hard tissue thickness, there was a decrease in soft tissue thickness, while in mid and lower ramal regions, it was noted that with a decrease in hard tissue thickness, there was an increase in soft tissue thickness. No significant difference was seen in the tooth-bearing section of the mandible (p > 0.05). Pearson's correlation showed a highly significant negative correlation between the hard and soft tissues of the GT at the level of the condyle and the ramus (p < 0.05). Non-significant correlation was seen between the hard and soft tissues at the molar, premolar and canine areas of the GT. No significant correlation between the hard and soft tissues was seen at any level in the GC (p > 0.05). Conclusion In the non-deviated side, the non-tooth-bearing segment of the mandible (condyle and ramus) showed differences between the hard and soft tissue thicknesses. With an increase in the hard tissue thickness, there was a corresponding decrease in the soft tissue thickness and vice versa which is attributed as compensation. The tooth-bearing segment of the non-deviated side did not show compensation. There is no compensation seen on the deviated side in both segments.

Three-Dimensional Analysis of the Cranial Base Structure in Patients with Facial Asymmetry

Facial asymmetry is often seen in patients with skeletal mandibular prognathism and is associated with deformities in the maxillofacial and head regions. The maxillofacial deviation is three-dimensional and affects not only the lateral deviation of the mandible and midface, but also the cranium. This study conducted a three-dimensional morphological evaluation of the cranial base morphology of patients with skeletal mandibular prognathism (ANB < 0°, Wits < 0 mm) with the aim of examining the relationship between deformities of the head region and facial asymmetry. Data obtained from computed tomography conducted during the initial examination of patients with and without skeletal mandibular prognathism with facial asymmetry were used. Differences in the position of structures present in the cranial base were measured, and the association between cranial deformities and mandibular deviation was assessed. The middle cranial base area and the lateral deviation of the mandibular fossa were significantly larger in patients with facial asymmetry compared to those without facial asymmetry. In addition, a correlation between the amount of mandibular deviation and the area of the anterior cranial base was identified in patients with significant cranial deformity (p = 0.012). Given the identified association between the structure of the head region and facial asymmetry, further studies are needed to determine the factors implicated in the growth process.

Age-Related Quality of Life and Psychosocial Impact of Chin Asymmetry in Adolescents and Young Adults Undergoing Orthodontic and Orthognathic Correction

Craniofacial asymmetry can have significant psychosocial implications, affecting the quality of life in adolescents and young adults. This study aimed to assess the impact of age and complexity of craniofacial asymmetry on quality of life and psychosocial outcomes in patients undergoing orthodontic and orthognathic correction. A cross-sectional study was conducted on 149 patients aged 13-26 years with moderate or severe craniofacial asymmetry that had a gnathion deviation higher than 2 mm, according to the American Association of Orthodontists. Participants were divided into three groups: teenagers (n = 53), adults (n = 46), and a control group (n = 50) with relative craniofacial asymmetry. Quality of life and psychosocial impacts were evaluated using validated questionnaires that measure health-related quality of life (SF-36), body image satisfaction and self-acceptance (BIQLI), anxiety and depression levels (HADS), and perceived stress (PSS-10). These tools provided an encompassing appraisal of the psychological and social implications associated with craniofacial asymmetry before and six months after orthodontic and orthognathic correction. Before the intervention, adults had higher mental health scores compared to teenagers (p = 0.037). At the 6-month follow-up, no significant differences in mental health scores were observed between the two groups (p = 0.121). BIQLI results showed significant differences in satisfaction with appearance and self-acceptance between teenagers and adults, both before intervention (p = 0.045 and p = 0.051, respectively) and at six months (p = 0.062 and p = 0.031, respectively). HADS results showed significant differences in anxiety levels before intervention (p = 0.039) but not at six months (p = 0.133). PSS-10 results showed no significant differences in perceived stress between the groups. In conclusion, this study demonstrates that craniofacial asymmetry significantly impacts the quality of life and psychosocial well-being of adolescents and young adults. Specifically, teenagers, as compared to young adults, reported lower satisfaction with their appearance and lower self-acceptance before intervention, underscoring the profound psychosocial challenges that adolescents with craniofacial asymmetry may experience. These age-related differences underscore the importance of tailored interventions to address unique psychosocial needs at different developmental stages.

Three-dimensional quantitative analysis of dental and skeletal characteristics of skeletal Class I unilateral posterior crossbite in adults

BACKGROUND

To study the dentoskeletal characteristics and the degree of compensations in skeletal Class I adults with unilateral posterior crossbite (UPCB).

METHODS

A sample of 40 adults was chosen for this cross-sectional study. 20 skeletal Class I adults with UPCB (mean age: 22.20 ± 2.88 years), were compared to 20 skeletal Class I adults with normal occlusion (mean age: 27.56 ± 5.76 years). The respective dentoskeletal measurements were made on cross-sectional images from cone-beam computed tomography scans.

RESULTS

Skeletally, both groups showed significant differences (P < 0.05) in mandibular corpus length and menton deviation with the UPCB group showing the greatest displacement. Maxillomandibular vertical asymmetry and condylar positional asymmetry were not significant in both groups (P > 0.05). For dental variables on the second premolar and first molar, the UPCB group showed greater linear and angular differences when compared to the control group (P < 0.05). On the crossbite side, maxillary posterior teeth were more buccally inclined, and mandibular posterior teeth were more lingually inclined. However, on the non-crossbite side, both maxillary and mandibular posterior teeth were lingually inclined.

CONCLUSION

Adults with UPCB showed distinct transverse dentoskeletal asymmetry. No asymmetry was found in the condylar position and the mandibular height in UPCB adults.

Quantitative analysis of facial symmetry by using three-dimensional technology

Background

Facial symmetry is becoming increasingly important in today's orthodontic treatment. But the asymmetrical boundary is not clearly demarcated. Stereophotogrammetry has a clear advantage in measuring facial asymmetry. The aim of this study was to quantify the facial asymmetry by three-dimensional (3D) technology as well as to study whether the evaluation by non-experts about facial asymmetry was consistent with the analysis by 3D technology.

Methods

The facial symmetry of 330 patients was evaluated by 10 non-experts. 3D facial images were taken using 3dMD stereophotogrammetry equipment. The original face and its mirror shell were divided into 7 regions and the surface matching was measured in the whole face and all regional areas. The degree of symmetry was calculated by the software 3-matic STL 9.0. The difference between the two groups was analyzed by Independent-Samples T Test and the diagnostic efficiency of symmetry degree was analyzed by ROC curve analysis. The consistency between the symmetric degree and the result of evaluation was analyzed by Pearson correlation analysis.

Results

The ROC analysis revealed significant diagnostic values in the determination of the facial asymmetry of lip, chin, cheek and lateral mandible areas. The cut-off values of symmetry degree were between 60 and 80%. The evaluation was middle correlation with the symmetric degree of the whole face.

Conclusions

The chin and lateral mandible contribute most significantly to the facial symmetry. The objective measurement of facial symmetry, 3D technology, is reliable.

Midsagittal Plane First: Building a Strong Facial Reference Frame for Computer-Aided Surgical Simulation

PURPOSE

A facial reference frame is a 3-dimensional Cartesian coordinate system that includes 3 perpendicular planes: midsagittal, axial, and coronal. The order in which one defines the planes matters. The purposes of this study are to determine the following: 1) what sequence (axial-midsagittal-coronal vs midsagittal-axial-coronal) produced more appropriate reference frames and 2) whether orbital or auricular dystopia influenced the outcomes.

METHODS

This study is an ambispective cross-sectional study. Fifty-four subjects with facial asymmetry were included. The facial reference frames of each subject (outcome variable) were constructed using 2 methods (independent variable): axial plane first and midsagittal plane first. Two board-certified orthodontists together blindly evaluated the results using a 3-point categorical scale based on their careful inspection and expert intuition. The covariant for stratification was the existence of orbital or auricular dystopia. Finally, Wilcoxon signed rank tests were performed.

RESULTS

The facial reference frames defined by the midsagittal plane first method was statistically significantly different from ones defined by the axial plane first method (P = .001). Using the midsagittal plane first method, the reference frames were more appropriately defined in 22 (40.7%) subjects, equivalent in 26 (48.1%) and less appropriately defined in 6 (11.1%). After stratified by orbital or auricular dystopia, the results also showed that the reference frame computed using midsagittal plane first method was statistically significantly more appropriate in both subject groups regardless of the existence of orbital or auricular dystopia (27 with orbital or auricular dystopia and 27 without, both P < .05).

CONCLUSIONS

The midsagittal plane first sequence improves the facial reference frames compared with the traditional axial plane first approach. However, regardless of the sequence used, clinicians need to judge the correctness of the reference frame before diagnosis or surgical planning.

Evaluation of facial soft tissue thickness in asymmetric mandibular deformities after orthognathic surgery

Objectives

The purpose of this study was to compare differences in facial soft tissue thickness in three-dimensional (3D) images before and after orthognathic surgery in patients with skeletal Class III malocclusion and to obtain a better understanding of the relationship between hard and soft tissue changes after surgery.

Materials and method

The present retrospective study included 31 patients with skeletal Class III malocclusion with mandibular chin deviation greater than 4 mm who had undergone cone-beam computed tomography before and 6 months after surgery. Seven bilateral points were established. Measurements were taken from software-generated multiplanar reconstructions. The predictor variables were timing (pre- and postoperatively) and side (deviated vs. nondedicated). A regression model and correlation analysis were conducted for statistical analysis.

Results

The difference of bilateral facial soft tissue thickness was statistically significantly different between deviated and nondeviated sides (P < 0.05), with lower values observed on the deviated side. The soft tissue thickness has become nearly symmetric at local regions of the lower thirds of the face after orthognathic surgery. However, most measurements showed a negative correlation between changes in soft tissue thickness and changes in bone tissues.

Conclusions

Skeletal Class III malocclusion with facial asymmetry is accompanied by differences in soft tissue thickness when comparing Dev and N-Dev sides of the posterior region of the mandible, where soft tissues are thinner on the Dev side. Soft tissue thickness can compensate for or camouflage the underlying asymmetric mandible. In addition, the asymmetric soft tissue thickness on the lower third of the face can be partially improved by orthognathic surgery, but the amount of soft tissue thickness change is not consistent with that of hard tissue positional change.

[Use of skeletal-related diagnostic methods in articles published from 2018 to 2020 in four major orthodontics journals]

Objective

To determine the skeletal-related diagnostic methods most commonly used according to the four most important orthodontics journals in the period from 2018 to 2020.

Methods

A review of the data available regarding the diagnostic procedures most frequently used to determine skeletal relationships in the four most important orthodontics journals from 2018 to 2020. Article review was performed using SCIMAGO 2018, which provides a series of parameters ranking the importance of the impact of publications and journals. We made a synopsis of the information analyzed to establish a correlation and compare sources, and critically examined the articles collected on the subject of interest. An online bibliographic search of databases including mainly Medline was carried out, followed by evaluation and selection of the bibliography, organized according to the significance and nature of the study.

Results

The four journals included in the bibliographic search were: AJODO, AO, EJO and KJO. The A point-Nasion-B point (ANB) method was used in 92.2% of the articles published in AJODO, and 7.8% did not describe the method used. Twenty-three articles in the AO journal were evaluated, all of which referred to the use of ANB as the method used. Finally, 16 and 11 articles from the EJO and KJO journals, respectively, were evaluated, with 93.8% and 95%, respectively of the articles using ANB as the method of choice for determining skeletal relationships.

Conclusion

The method of choice for skeletal-related diagnostics is ANB, although this widely known method presents a risk of geometric effect.

Landmark annotation and mandibular lateral deviation analysis of posteroanterior cephalograms using a convolutional neural network

Background/purpose

Facial asymmetry is relatively common in the general population. Here, we propose a fully automated annotation system that supports analysis of mandibular deviation and detection of facial asymmetry in posteroanterior (PA) cephalograms by means of a deep learning-based convolutional neural network (CNN) algorithm.

Materials and methods

In this retrospective study, 400 PA cephalograms were collected from the medical records of patients aged 4 years 2 months-80 years 3 months (mean age, 17 years 10 months; 255 female patients and 145 male patients). A deep CNN with two optimizers and a random forest algorithm were trained using 320 PA cephalograms; in these images, four PA landmarks were independently identified and manually annotated by two orthodontists.

Results

The CNN algorithms had a high coefficient of determination (R ² ), compared with the random forest algorithm (CNN-stochastic gradient descent, R ²  = 0.715; CNN-Adam, R ²  = 0.700; random forest, R ²  = 0.486). Analysis of the best and worst performances of the algorithms for each landmark demonstrated that the right latero-orbital landmark was most difficult to detect accurately by using the CNN. Based on the annotated landmarks, reference lines were defined using an algorithm coded in Python. The CNN and random forest algorithms exhibited similar accuracy for the distance between the menton and vertical reference line.

Conclusion

Our findings imply that the proposed deep CNN algorithm for detection of facial asymmetry may enable prompt assessment and reduce the effort involved in orthodontic diagnosis.

Influence of dental education on eye gaze distribution when observing facial profiles with varying degrees of lip protrusion

OBJECTIVES

The purpose of the present study was to investigate the influence of dental education on eye gaze distribution when perceiving facial profile images with varying degrees of lip protrusion.

METHODS

Fifty-one subjects with dental education (dental-education group) and 47 without dental education (no-dental-education group) were included in this study. The eye gaze distribution of the subjects was recorded for 10 seconds using a non-contact eye tracker when determining whether or not the subjects judged each various facial profile image inappropriate. The facial profile images had varying degrees of upper-lip and lower-lip protrusion. The frequency of eye fixation (lasting >0.06 seconds) was counted. The duration was measured as the total time of eye fixation. The facial images were divided into 4 regions of interest (ROIs): the forehead (ROI-I); the orbit and nose root (ROI-II); the nose tip and upper lip (ROI-III); and the lower lip and chin (ROI-IV). The frequency and duration of eye fixation on each ROI was compared.

RESULTS

The frequency of eye fixation on ROI-II was greater in comparison to ROI-I and ROI-IV. The frequency of eye fixation on ROI-III was also greater in comparison to ROI-I and ROI-IV. The duration of eye fixation on ROI-III in the dental-education group was longer in comparison to the no-dental-education group.

CONCLUSIONS

Dental education influenced the eye fixation on the nose tip and upper lip when perceiving facial profile images.

Effect of Botulinum Toxin Injection on Asymmetric Lower Face with Chin Deviation

The purpose of this study was to compare the efficacy of botulinum toxin (BoNT) in masseter muscle reduction depending on the amount of chin deviation. Exploring distinctive effects of BoNT relative to the characteristics of facial asymmetry will aid in planning and predicting treatment outcomes. Sixteen adult volunteers were classified into two groups according to the degree of menton deviation observed in posteroanterior cephalograms. Eight had a menton deviation of 3 mm or more and the other eight had less than 3 mm. A total of 25 Units of BoNT was injected into the unilateral masseter muscle of the prominent side for each participant. Changes in the volume and bulkiest height of the lower face on each side were measured with a 3D laser scan at four time points: before and 4, 8, and 12 weeks after the injection. Two-way mixed ANOVA was employed for analyses. The volume and bulkiest height of the injected side decreased over time in both types of asymmetry, with significant differences at each time point. The reductions in the volume and bulkiest height were significantly greater in subjects without chin deviation. The reductions in the volume and bulkiest height of the lower face using BoNT are more effective for subjects without chin deviation.

Quantification of three-dimensional facial asymmetry for diagnosis and postoperative evaluation of orthognathic surgery

Background

To evaluate the facial asymmetry, three-dimensional computed tomography (3D-CT) has been used widely. This study proposed a method to quantify facial asymmetry based on 3D-CT.

Methods

The normal standard group consisted of twenty-five male subjects who had a balanced face and normal occlusion. Five anatomical landmarks were selected as reference points and ten anatomical landmarks were selected as measurement points to evaluate facial asymmetry. The formula of facial asymmetry index was designed by using the distances between the landmarks. The index value on a specific landmark indicated zero when the landmarks were located on the three-dimensional symmetric position. As the asymmetry of landmarks increased, the value of facial asymmetry index increased. For ten anatomical landmarks, the mean value of facial asymmetry index on each landmark was obtained in the normal standard group. Facial asymmetry index was applied to the patients who had undergone orthognathic surgery. Preoperative facial asymmetry and postoperative improvement were evaluated.

Results

The reference facial asymmetry index on each landmark in the normal standard group was from 1.77 to 3.38. A polygonal chart was drawn to visualize the degree of asymmetry. In three patients who had undergone orthognathic surgery, it was checked that the method of facial asymmetry index showed the preoperative facial asymmetry and the postoperative improvement well.

Conclusions

The current new facial asymmetry index could efficiently quantify the degree of facial asymmetry from 3D-CT. This method could be used as an evaluation standard for facial asymmetry analysis.

Facial asymmetry correction: From conventional orthognathic treatment to surgery-first approach

The surgery-first approach (SFA), which proceeds without presurgical orthodontic treatment, is assumed to shorten the treatment course because the direction of post-surgical orthodontic tooth movement conforms to the normal muscular forces. Moreover, the regional acceleratory phenomenon (RAP), evoked by surgery, helps in tooth alignment and compensation in a faster way. Although SFA has definite advantages, especially in class III individuals, there is a lack of data about its indications in patients with facial asymmetry. In this article, we reviewed recently published articles on the treatment of asymmetric patients using the SFA. Different aspects, including the three-dimensional assessment of stability in different planes, approaches for fabrication of a surgical splint, predictability of the results, skills needed for bimaxillary surgery, indications as the treatment of choice for condylar hyperplasia, and combination with distraction osteogenesis in candidates with severe asymmetries were found to be the main topics discussed for patients presenting with facial asymmetry

Aesthetic facial perception and need for treatment in simulated laterognathism in male faces of different ethnicities

PURPOSE

This study aimed to compare the aesthetic perception and treatment need in individuals of different ethnicities with various degrees of laterognathism assessed by orthodontists, oral and maxillofacial surgeons, and laypersons.

METHODS

Three male descendants of different ethnicities were assessed, in which the mandibular deviation was manipulated digitally in different angulations (from 0 to 8°). The assessment was performed by three groups (orthodontists, maxillofacial surgeons, and laypersons (n = 20)), and it consisted of scoring the degree of pleasantness of the images presented in a numerical scale and indicating or not a corrective treatment for the respective image.

RESULTS

The higher the degree of deviation, the lower the scores assigned to the image (p < 0.05). Laypersons assigned the highest scores, with a significant difference between laypersons and oral and maxillofacial surgeons (p < 0.05). In terms of treatment need according to the group of evaluators, there were no statistically significant differences among them (p > 0.05). Moreover, the increase in degree of deviation increased the perception of treatment need (p < 0.05). The African faces received the highest scores, with significant differences from the Caucasian faces (p < 0.05). The overall tendency was higher treatment indication for the Caucasian faces, with statistically significant differences from the African faces (p < 0.05).

CONCLUSION

The greater the mandibular deviation, the lower the aesthetic pleasantness. Laypersons are less critical regarding the assessment of mandibular deviation. There was no difference for treatment indication by the different groups of evaluators. In addition, ethnicity may influence the perception and treatment indication.

Comparison of maxillomandibular asymmetries in adult patients presenting different sagittal jaw relationships

OBJECTIVE

The present study aims at using cone beam computed tomography (CBCT) to analyze the maxillomandibular characteristics present in adults with mandibular asymmetries and different sagittal jaw relationships.

METHODS

360 patients were selected and divided into three groups (Class I, Class II, and Class III), with 120 individuals per group. The groups were then subdivided according to the intensity of lateral deviation of the gnathion point, into: 1) relative symmetry, 2) moderate asymmetry, and 3) severe asymmetry. Three planes of reference were established in the CBCT images and several measurements were taken to compare the bilateral skeletal differences between the intensities of asymmetry for the different sagittal jaw relationships.

RESULTS

When the groups were compared by the intensity of asymmetry, significant differences among patients with relative symmetry and moderate to severe asymmetry were found. This was especially noticed for severe asymmetry, suggesting that the deviation of the chin did not constitute the only morphological alteration for these patients, especially because a series of measurements showed significant bilateral differences. When comparing sagittal jaw relationships, the only significant finding was the vertical positioning of the gonion between Class II and III patients with severe asymmetry.

CONCLUSIONS

When comparing the three sagittal jaw relationships with the same intensity of asymmetry, most maxillofacial aspects were quite similar. The only difference was found for patients with severe asymmetry, as the individuals with Class II showed greater bilateral difference in the vertical positioning of the gonion, when compared to patients with Class III.

Facial Contouring by Using Dermal Fillers and Botulinum Toxin A: A Practical Approach

BACKGROUND

The perception of an attractive face is largely subjective. The purpose of this paper is to provide an insight and a practical approach to facial contouring management with hyaluronic acid (HA) implants and botulinum toxin A.

METHODS

This study is presenting the clinical experience of the authors regarding facial contouring. After a careful medical history, patients underwent an exhaustive aesthetic assessment that includes photographs and videos. Realistic treatment goals were discussed and agreed with the patient. Comprehensive treatment strategies for facial contouring, including HA implants and/or botulinum toxin A injections, were selected according to the patient needs.

RESULTS

Based on the MD codes^®, developed by Mauricio de Maio, these treatment strategies have been adapted to six different basic categories of facial shapes, namely round, square, triangular, inverted triangle, rectangle, oval and oblong faces. The incidence of complications was low and, in all the cases, was mild (edema, erythema and local ecchymosis), of limited duration, and was resolved without sequela.

CONCLUSIONS

The current article presented the personal experiences of the authors on a specific subject, and this fact should be considered when interpreting data from this paper. As other aesthetic treatments, facial contouring should be focused on the patient needs and to select a specific aesthetic approach according to different facial shapes. Finally, it is essential to have a good understanding of the potential associated complications, because it will help the specialist to take the necessary precautions to prevent them, and if they ever arise, to be able to deal with them effectively.

LEVEL OF EVIDENCE IV

This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

[Orthognathic surgery of mandibular asymmetry: which results can we expect with and without chin wing? A cohort out of 51 cases]

INTRODUCTION

The aim of this retrospective cohort is to evaluate the amount of postsurgical correction of soft and hard tissues in patients with mandibular asymmetries and to compare the results with and without surgery of the lower mandibular contour (chin wing…).

MATERIAL AND METHOD

Mandibular asymmetries cases of three surgeons were systematically included. The angles of deviation of the chin, bi-commissural, bi-gonic and occlusal were measured on face photography and radiography. A pre and post-surgical comparison was performed and the amount of correction was analyzed via the Wilcoxon statistical test.

RESULTS

51 patients (44 women and 7 men) were included. After surgery, the correction is significant for all measurements with an improvement of 44 to 60% depending on the measured angles. No patient is normalized but the small initial mandibular asymmetries are the closest to normal after surgery. The correction of the bi-commissural angle is controlled without being optimal (60% correction). The difficulty remains the horizontalization of the bi-gonial plan which is only corrected at 45%. Patients with mandibular margin surgery (chin wing…) showed the greatest improvement in bi-gonial (p = 0.0142) and occlusal (p = 0.0154) angles.

CONCLUSION

If surgery allows a significant correction of facial dissymmetry, this is not complete. Surgical procedures on the lower edge of the mandible such as the chin wing could provide a better correction especially for bi-gonial and occlusal angles.

Diagnosis and Surgical Outcomes of Facial Asymmetry According to the Occlusal Cant and Menton Deviation

PURPOSE

Morphologic differences and surgical outcomes were compared between the ipsilateral type of facial asymmetry, in which the menton deviates to the side of the upward frontal occlusal plane (FOP) cant (FOP_UP), and the contralateral type, in which the menton deviates to the side of the downward FOP cant (FOP_DOWN), by using cone beam computed tomography (CBCT) images.

MATERIALS AND METHODS

This retrospective study included consecutive patients with skeletal Class III malocclusion and facial asymmetry who had undergone bimaxillary orthognathic surgery and serial CBCT before, 1 month after, and 1 year after surgery. CBCT images were reconstructed and analyzed for predictor (group and timing) and outcome (CBCT measurements over time) variables. The data were analyzed using independent t tests and paired t tests.

RESULTS

The contralateral group (n = 12) was selected first; the ipsilateral group (n = 12) was selected by matching age, gender, and degree of FOP cant with those of the contralateral group. Before surgery, in the ipsilateral group, the ramal length was longer on the nondeviated (N-Dev) side than on the deviated (Dev) side (P < .05) whereas the mandibular body length showed no significant difference (P > .05). In the contralateral group, the ramal length was longer on the Dev side (P < .05) whereas the mandibular body length was longer on the N-Dev side (P < .01). One year after surgery, most measurements were corrected symmetrically in both groups (P > .05); however, the hemi-lower facial area remained asymmetrical in the contralateral group (P < .05).

CONCLUSIONS

Differences in ramal lengths in the ipsilateral group and mandibular body lengths in the contralateral group between the Dev and N-Dev sides seemed to be the main cause of facial asymmetry. Although facial asymmetry improved after surgery in both groups, asymmetry in the soft tissue remained in the contralateral group 1 year after surgery.

Mandibular asymmetries and associated factors in orthodontic and orthognathic surgery patients

OBJECTIVES

To estimate the prevalence of mandibular asymmetries in orthodontic and orthognathic surgery patients and to investigate demographic and skeletal factors associated with this disharmony.

MATERIALS AND METHODS

Cone-beam computed tomography images of 1178 individuals aged 19 through 60 years with complete dentitions were analyzed. Outcomes were classified as relative mandibular symmetry, moderate asymmetry, and severe asymmetry. Factors recorded included sex, age, side of mandibular deviation, sagittal jaw relationship, vertical skeletal pattern, angle of the cranial base, and maxillary asymmetry. Ordinal logistic regression was used to estimate simple and adjusted odds ratios (OR) for the individuals with moderate and severe mandibular asymmetry, as well as 95% confidence intervals.

RESULTS

Prevalence values of 55.2%, 27.2%, and 17.6% were observed for relative mandibular symmetry, moderate asymmetry, and severe asymmetry, respectively. An independent association with the side of mandibular deviation and the presence of maxillary asymmetry was observed, both for subjects with moderate mandibular asymmetry (left side: OR = 1.50; 95% CI: 1.01-2.24 / maxillary asymmetry: OR = 2.07; 95% CI: 1.11-3.76) and for those with severe asymmetry (left side: OR = 2.09; 95% CI: 1.27-3.44 / maxillary asymmetry: OR = 4.93; 95% CI: 2.64-9.20).

CONCLUSIONS

Moderate and severe mandibular asymmetries were present in 44.8% of the sample, being associated with the side of mandibular deviation and with maxillary asymmetry.

Digital platform for planning facial asymmetry orthodontic-surgical treatment preparation

Dentofacial deformities usually are surgically treated, and 3D virtual planning has been used to favor accurate outcomes. Cases reported in the present article show that orthognathic surgery carried out to correct facial asymmetries does not comprise only one treatment protocol. 3D virtual planning might be used for surgical planning, but it should also be used to diagnose the deformity, thus allowing for an analysis of the best-recommended possibilities for the orthodontic preparation that suits each individual case.

[Mandibular asymmetry: determination of a reliable skin measurement technique]

INTRODUCTION

Clinical measurements in the frontal view underevaluate chin deviation in mandibular asymmetry. The aim of this descriptive study is to search for a reliable method of measuring deviant chins using a facial X-ray as reference.

MATERIAL AND METHOD

Seventy patients with mandibular asymmetry who had consulted a maxillofacial surgeon were systematically included. Age, sex, cephalometric characteristics, reasons for patient consultation and type of surgery were collected. Two cephalometric methods were tested with respect to the medial sagittal plane (PSM) to compare the assessment of mandibular asymmetry on soft tissue and by cephalometry.

RESULTS

On average, the patients selected were young (26 years +/- 9), women (75% of cases), presented open bite (average FMA: 28° +/- 8°), a skeletal class III tendency, a left-side shift of the chin (63% of cases). They consulted for both aesthetic and functional reasons (51% of cases) and required bimaxillary surgery (66% of cases). Comparison between the photographic angle (formed by the PSM and the line passing through the nasion and reaching the chin point) and the radiographic angle (formed by the PSM and the line passing through the Crista Galli process and the bony chin point angle) showed no significant difference (p = 0.937) and is thus reliable.

Three-dimensional evaluation of craniofacial characteristics related to mandibular asymmetries in skeletal Class I patients

INTRODUCTION

Our objective was to analyze the characteristics that affect skeletal Class I adults with mandibular asymmetries using cone-beam computerized tomography.

METHODS

The sample included cone-beam computerized tomography images of 120 subjects. Asymmetry was determined by the deviation of gnathion from the midsagittal plane and classified as relative symmetry, moderate asymmetry, or severe asymmetry. Maxillary and mandibular measurements were made, and the differences between the contralateral side and the deviated side were evaluated, as well as the differences between the categories of asymmetry.

RESULTS

For patients with moderate asymmetry, there were significant differences between the contralateral and deviated sides for some measuments in the transverse and vertical planes. For those with severe asymmetry, statistically significant differences were found between the sides for all measurements, except for the measuments that evaluated the position of the mandibular condyle in the transverse and sagittal directions. Furthermore, a strong correlation was found in patients with severe asymmetry, between the deviation of the mandibular dental midline and the lateral displacement of gnathion.

CONCLUSIONS

Patients with relative symmetry had a bilateral balance, whereas those with moderate and severe asymmetries showed several skeletal imbalances. A great deviation of the mandibular dental midline may indicate severe skeletal asymmetry in Class I adults.

Is there an association between skeletal asymmetry and tooth absence?

Introduction:

Facial skeletal asymmetry is commonly found in humans and its main characteristic is menton deviation. The literature suggests that occlusal and masticatory problems arising from tooth absence could be related to the development of such asymmetries.

Objective:

The aim of this cross-sectional study was to estimate the prevalence of mandibular skeletal asymmetries and to investigate its association with posterior tooth absences.

Methods:

Tomographic images of 952 individuals aged from 18 to 75 years old were used. Asymmetry was the analyzed outcome, and it was categorized into three groups according to gnathion displacement in relation to the midsagittal plane (relative symmetry, moderate asymmetry, and severe asymmetry). Patients were sorted by the presence of all posterior teeth, unilateral posterior tooth absence, or bilateral posterior tooth absence. Chi-square test with a significance level of 5% was used to verify the association between posterior tooth absence and asymmetry.

Results:

Results show relative symmetry present in 55.3% of the sample, as well as the prevalence of 27.3% for moderate mandibular asymmetry and 17.4% for severe asymmetry. Moderate and severe mandibular asymmetries occurred in a higher proportion in patients with unilateral posterior tooth absence. However, there was no statistically significant difference between the analyzed groups (p = 0.691).

Conclusions:

In this study, mandibular asymmetries did not present any association with the absence of teeth on the posterior area of the arch.

Facial asymmetry: a current review

The term "asymmetry" is used to make reference to dissimilarity between homologous elements, altering the balance between structures. Facial asymmetry is common in the overall population and is often presented subclinically. Nevertheless, on occasion, significant facial asymmetry results not only in functional, but also esthetic issues. Under these conditions, its etiology should be carefully investigated in order to achieve an adequate treatment plan. Facial asymmetry assessment comprises patient's first interview, extra- as well as intraoral clinical examination, and supplementary imaging examination. Subsequent asymmetry treatment depends on patient's age, the etiology of the condition and on the degree of disharmony, and might include from asymmetrical orthodontic mechanics to orthognathic surgery. Thus, the present study aims at addressing important aspects to be considered by the orthodontist reaching an accurate diagnosis and treatment plan of facial asymmetry, in addition to reporting treatment of some patients carriers of such challenging disharmony.

Analyzing Menton Deviation in Posteroanterior Cephalogram in Early Detection of Temporomandibular Disorder

INTRODUCTION

Some clinicians believed that mandibular deviation leads to facial asymmetry and it also had a correlation with temporomandibular disorders (TMDs). Posteroanterior (PA) cephalogram was widely reported as a regular record in treating facial asymmetry and craniofacial anomalies. The objective of this study was to analyze the relationship of menton deviation in PA cephalogram with temporomandibular disorders (TMDs) symptoms.

MATERIALS AND METHODS

TMJ function was initially screened based on TMD-DI questionnaire. PA cephalogram of volunteer subjects with TMDs (n = 37) and without TMDs (n = 33) with mean age of 21.61 ± 2.08 years was taken. The menton deviation was measured by the distance (mm) from menton point to midsagittal reference (MSR) horizontally, using software digitized measurement, and categorized as asymmetric if the value is greater than 3 mm. The prevalence and difference of menton deviation in both groups were evaluated by unpaired t-test.

RESULT

The prevalence of symmetry group showed that 65.9% had no TMDs with mean of 1,815 ± 0,71 mm; in contrast, the prevalence of asymmetry group showed that 95.5% reported TMDs with mean of 3,159 ± 1,053 mm. There was a significant difference of menton deviation to TMDs (p = 0.000) in subjects with and without TMDs.

CONCLUSION

There was a significant relationship of menton deviation in PA cephalogram with TMDs based on TMD-DI index.

Craniofacial features affecting mandibular asymmetries in skeletal Class II patients

OBJECTIVES

The aim of this study was to evaluate the characteristics affecting different intensities of mandibular asymmetry in skeletal Class II adults using three-dimensional images. This study is clinically relevant since it allows professionals to evaluate the morphological components related to these deformities and more carefully obtain correct diagnosis and treatment plan for such patients.

METHODS

Cone-beam computed tomography data of 120 Class II patients (40 with relative symmetry, 40 with moderate asymmetry, and 40 with severe asymmetry) were imported to SimPlant Ortho Pro^® 2.0 software (Dental Materialise, Leuven, Belgium). Three reference planes were established and linear measurements were performed from specific landmarks to these planes, comparing the deviated side and the contralateral side in each group, as well as the differences between groups. The correlation between midline mandibular asymmetry and other variables was also evaluated. Statistical analyses considered a significance level of 5%.

RESULTS

Comparing the values obtained on the deviated side and on the contralateral side, there were significant differences for patients with moderate asymmetry and severe asymmetry. However, differences were seen more often in severe mandibular asymmetries. In those patients, there was a significant correlation of the gnathion deviation with lower dental midline deviation, difference in the lateral gonion positions, difference in the mandibular rami heights, and difference in the jugale vertical displacements.

CONCLUSIONS

For skeletal Class II patients with mandibular asymmetry, some craniofacial features are related to chin deviation and require proper evaluation, including the bilateral differences in the ramus height, mandibular body length, transverse and vertical positioning of the gonion and jugale points.

Relationship between molar occlusion and masticatory movement in lateral deviation of the mandible

INTRODUCTION

The relationship between molar occlusion and chewing patterns was examined in subjects with laterally deviated mandibles.

METHODS

Twenty-three patients with mandibular deviation from the midline (4 mm or more) and skeletal Class I (0° ≤ANB ≤4°) were divided into 2 groups: normal bite and crossbite. The chewing pattern was classified as normal, reversed, or crossover.

RESULTS

The normal bite group had a normal chewing pattern on the affected side 100% of the time and a reversed chewing pattern on the affected and unaffected sides 0% and 7.2% of the time, respectively. Additionally, the normal bite group showed no evidence of a crossover chewing pattern and also had significantly less axial inclination of the mandibular teeth on the affected side compared with the crossbite group; lingual inclination was also evident. The crossbite group had a normal chewing pattern on the affected and unaffected sides 0% and 55.6% of the time, respectively, and reversed and crossover chewing patterns on the affected side 55.6% and 44.4% of the time, respectively.

CONCLUSIONS

A normal chewing pattern tends to result in lingual axial inclination of the mandibular molars on the affected side, as well as a more consistent chewing pattern.

Prevalence and Associated Factors of Mandibular Asymmetry in an Adult Population

BACKGROUND

This study aimed to estimate the prevalence of mandibular asymmetry and investigate some associated factors.

METHODS

Tomographic images of 952 individuals aged from 18 to 75 years old were analyzed. The investigated outcome was mandibular asymmetry. The explanatory variables included gender, age, absence of posterior teeth, and sagittal jaw relationship of the individuals. Statistical analyses included the chi-squared and the Poisson regression with robust variance.

RESULTS

Mandibular asymmetry was present in 17.4% of the sample (95% confidence interval 15.2-20.0). In the bivariate analysis, there was an association between the variables age and sagittal jaw relationship with mandibular asymmetry (P = 0.026 and P = 0.018, respectively). However, in the adjusted regression model, the association with age was not maintained, occurring only an association between sagittal jaw relationship and mandibular asymmetry (P = 0.045), with significant difference between individuals with skeletal Class II and skeletal Class III (P = 0.013).

CONCLUSION

Mandibular asymmetry was not independently associated with sex, age, or absence of posterior teeth. The only verified independent association was between mandibular asymmetry and sagittal jaw relationship.

Three-dimensional analysis of upper airway morphology in skeletal Class III patients with and without mandibular asymmetry

OBJECTIVE

To compare the three-dimensional (3D) morphology of the upper airway in skeletal Class III patients with and without mandibular asymmetry and to investigate the possible underlying correlations between the morphology of the upper airway and mandibular deviation.

MATERIALS AND METHODS

Cone-beam computed tomography images of 54 subjects with skeletal Class III malocclusion (ANB angle ≤ 0.4°, Wits ≤ -5.5°) were taken and 3D upper airway models were reconstructed using Dolphin 3D software. According to the distance (d) from symphysis menti to the sagittal plane, all subjects were divided into a symmetry group (d ≤ 2 mm) and an asymmetry group (d ≥ 4 mm). Based on the severity of mandibular deviation, the asymmetry group was divided into subgroup I (4 mm ≤d <10 mm) and subgroup II (d ≥ 10 mm). Cross-sectional linear distances, areas, and volumetric variables of the upper airway were measured in the 3D airway model.

RESULTS

Width of the inferior limit of the glossopharynx (P3W), cross-sectional area of the anterior limit of the nasal airway (P5S), and height of the glossopharynx (GPH) in the asymmetry group were significantly larger than in the symmetry group. As for subjects with severe mandibular deviation in subgroup II (d ≥ 10 mm), volume of the glossopharynx (GPV), total volume of the pharynx (TPV), length of the inferior limit of the velopharynx (P2L), and ratio of length to width of the inferior limit of the velopharynx (P2L/P2W) showed significantly negative correlations with mandibular deviation (r > 0.7, P < .05).

CONCLUSIONS

In Class III subjects with severe mandibular asymmetry, the pharyngeal airway showed a tendency toward constriction and presented a more elliptical shape as mandibular deviation became more severe (P < .01).

Transverse dental compensation in relation to sagittal and transverse skeletal discrepancies in skeletal Class III patients

INTRODUCTION

The purposes of this study were to compare the buccolingual inclinations of the posterior teeth in skeletal Class III patients with and without facial asymmetry with those of skeletal Class I patients and to investigate their relationships with sagittal and transverse skeletal discrepancies.

METHODS

Sixty-three skeletal Class III adult patients were divided into 2 groups according to the degree of menton deviation: a symmetry group with deviation less than 2 mm (n = 30), and an asymmetry group with deviation greater than 4 mm (n = 33). The control group comprised 25 skeletal Class I patients. The buccolingual inclinations of the posterior teeth measured on cone-beam computed tomography images were compared among the 3 groups, and regression analysis was performed to investigate the relationships between the inclinations and the sagittal and transverse skeletal discrepancies.

RESULTS

The symmetry group showed greater buccal inclinations of the maxillary posterior teeth and lingual inclinations of the mandibular second molars than did the control, and this was correlated with the ANB angles. The deviated sides in the asymmetry group showed the greatest transverse dental compensation, which was correlated with menton deviation, whereas the nondeviated sides showed no significant transverse dental compensation.

CONCLUSIONS

Transverse dental compensation is closely related to sagittal and transverse skeletal discrepancy in skeletal Class III patients.

Analysis of Facial Asymmetry

Facial symmetry is an important component of attractiveness. However, functional symmetry is favorable to aesthetic symmetry. In addition, fluctuating asymmetry is more natural and common, even if patients find such asymmetry to be noticeable. However, fluctuating asymmetry remains difficult to define. Several studies have shown that a certain level of asymmetry could generate an unfavorable image. A natural profile is favorable to perfect mirror-image profile, and images with canting and differences less than 3°-4° and 3-4 mm, respectively, are generally not recognized as asymmetry. In this study, a questionnaire survey among 434 medical students was used to evaluate photos of Asian women. The students preferred original images over mirror images. Facial asymmetry was noticed when the canting and difference were more than 3° and 3 mm, respectively. When a certain level of asymmetry is recognizable, correcting it can help to improve social life and human relationships. Prior to any operation, the anatomical component for noticeable asymmetry should be understood, which can be divided into hard tissues and soft tissue. For diagnosis, two-and three-dimensional (3D) photogrammetry and radiometry are used, including photography, laser scanner, cephalometry, and 3D computed tomography.

Evaluation of intra-articular distance narrowing during temporomandibular joint movement in patients with facial asymmetry using 3-dimensional computed tomography image and tracking camera system

INTRODUCTION

Functional overloading can lead to disc displacement in the temporomandibular joint (TMJ), and a high incidence of disc displacement has been reported in patients with facial asymmetry. The aim of this study was to assess the dynamic condylar movement in patients (n = 26) with facial asymmetry using a simulation system with 3-dimensional computed tomographic images and tracking camera system.

MATERIAL AND METHODS

The intra-articular distance (IAD) between the condyle and glenoid fossa was recorded during TMJ movement as a parameter for functional overloading and compared between Group I with severe asymmetry and Group II with mild asymmetry.

RESULTS

The average IAD was shorter in Group I than Group II, especially at the lowest point (P < 0.05). The ratio of IAD narrowing in Group I was significantly larger than in Group II (P < 0.05). The mean IAD were slightly smaller on the deviated side (3.41 mm) than on the nondeviated side (3.55 mm) in Group I, even though there was no statistical significance. The maximum displacement in Group I was longer than in Group II and had no significant difference between deviated side and nondeviated side.

CONCLUSION

We suggested that the reduced IAD resulting from TMJ overloading can lead to internal derangement in severe facial asymmetry.

Use of spherical coordinates to evaluate three-dimensional facial changes after orthognathic surgery

Purpose

This study aimed to assess the three-dimensional (3D) facial changes after orthognathic surgery by evaluating the spherical coordinates of facial lines using 3D computed tomography (CT).

Materials and Methods

A 19-year-old girl was diagnosed with class III malocclusion and facial asymmetry. Orthognathic surgery was performed after orthodontic treatment. Facial CT scans were taken before and after orthognathic surgery. The patient had a menton deviation of 12.72 mm before surgery and 0.83 mm after surgery. The spherical coordinates of four bilateral facial lines (ramal height, ramal lateral, ramal posterior and mandibular body) were estimated from CT scans before and after surgery on the deviated and opposite side.

Results

The spherical coordinates of all facial lines changed after orthognathic surgery. Moreover, the bilateral differences of all facial lines changed after surgery, and no bilateral differences were zero.

Conclusion

The spherical coordinate system was useful to compare differences between the presurgical and postsurgical changes to facial lines.

Extraction decision and identification of treatment predictors in Class I malocclusions

BACKGROUND

The extraction rate in orthodontics varies throughout the years. While the extraction decision is easily made or excluded in clear-cut cases, it still remains controversial what makes an orthodontist decide to extract in borderline cases. The aim of this retrospective study was to identify the percentage of extraction cases in a large group of Class I malocclusions and to clarify which variables contributed most to the extraction decision.

METHODS

The sample consisted of 542 randomly selected records of Class I patients treated in a university graduate program and in five private orthodontic offices. Of these patients, 331 were female and 211 male. The mean age was 14.55 (standard deviation (SD) 5.36) for the non-extraction group and 14.52 (SD 4.86) for the extraction group. The extensive series of 32 linear and angular measurements derived from the cephalometric analysis and the dental casts, along with the variables of age and gender, fueled a stepwise discriminant analysis.

RESULTS

The percentage of the patients treated with four first premolar extractions was 26.8%. The results showed that the variables of lower crowding, lower lip to E-plane, upper crowding, and overjet accounted most for the decision to extract at a very significant level (Sig. 0.000). The discriminant analysis assigned a classification power of 83.9% to the predictive model (p<0.0001). Fisher's linear discriminant functions provided a mathematical model, according to which any case can be classified into the adequate treatment group.

CONCLUSIONS

In a large contemporary sample of 542 Class I patients, the extraction rate was 26.8%. The most important measurements when the orthodontist decides extractions in Class I cases are lower crowding, lower lip to E-plane, upper crowding, and overjet. In clinical orthodontic practice, the findings facilitate treatment by providing evidence-based treatment predictors for Class I malocclusions.

Three-dimensional cone beam computed tomographic image reorientation using soft tissues as reference for facial asymmetry diagnosis

OBJECTIVE

To investigate discrepancies in results of facial asymmetry analysis using different cone beam computed tomography (CBCT) image reorientation methods and the effectiveness of soft tissue as a reorientation reference for analysis of facial asymmetry.

MATERIALS AND METHODS

An asymmetric group of 30 patients with 4 mm or more of chin point (menton [Me]) deviation and a symmetric group of 30 patients with less than 4 mm of deviation of Me were chosen as study subjects. Three orientation methods were used to calculate and compare Me deviation values of the 60 subjects. Two methods used only skeletal landmarks for reference, and one method included the soft tissue landmarks around the eye. Preferences of an expert group for the facial midline as determined by each reorientation method were also examined.

RESULTS

The examinations showed significant discrepancies in Me deviation values between the three reorientation methods. The expert group showed the greatest preference for the facial midline reorientation method that incorporated soft tissue landmarks of the eye.

CONCLUSIONS

These study findings suggest that the inclusion of soft tissue landmarks, especially those around the eyes, is effective for three-dimensional CBCT image reorientation for facial asymmetry analysis.

Posteroanterior cephalometric changes in subjects with temporomandibular joint disorders

OBJECTIVES

The aim of the study was to establish the changes in posteroanterior cephalometric variables in subjects with temporomandibular joint disorders (TMDs).

METHODS

Posteroanterior cephalograms of 61 subjects (age range 16-36.6 years, standard deviation 4.88 years) were used to determine cephalometric differences. Subjects were classified according to the Research Diagnostic Criteria for Temporomandibular Joint Disorders into three groups: unilateral TMD, bilateral TMD and no TMD. 14 linear and angular measurements were assessed on the posteroanterior cephalogram. For assessing facial asymmetry, the asymmetry index for bilateral measurements was calculated between the right and the left side. In cases with unilateral TMD, the asymmetry index was calculated using the difference between the unaffected and affected side. The differences among multiple groups were analysed using the one-way analysis of variance test and Scheffé post hoc test.

RESULTS

47 subjects were females (77%) and 14 were males (23%). 19 subjects had unilateral TMDs and 16 subjects had bilateral TMDs. The asymmetry index of the distance from the horizontal plane to the antegonion was higher in subjects with unilateral TMD than in patients with bilateral or no TMD (p < 0.05). Also, the asymmetry index of the distances from the vertical plane to the condyle (p = 0.05), gonion (Go) (p = 0.0004), antegonion (p = 0.002) and chin (Ch) (p = 0.02) was higher in subjects with unilateral TMDs. The asymmetry index of the O point-Go-Go' and O point-Ch-Ch' angles differed significantly in subjects with unilateral TMDs (p < 0.05).

CONCLUSIONS

Unilateral TMDs are associated with changes in posteroanterior cephalometric measurements. The assessment of posteroanterior cephalometric variables could be used as a key factor for evaluating the presence of TMDs.

The science of anterior teeth selection for a completely edentulous patient: a literature review

Esthetic replacement and physiological tooth arrangement made the complete denture biologically compatible and desirable. Proper placement of tooth should be functional and esthetically pleasing to enhance the psychology of the patient. This article reviews the evolution of concepts for teeth selection and the recent techniques employed for selecting anterior teeth for complete dentures.