Luca Pisoni

Three-Dimensional Facial Asymmetry in Attractive and Normal People from Childhood to Young Adulthood

We are currently investigating measurable esthetic characteristics in persons considered “attractive” by the media. Three-dimensional soft-tissue facial asymmetry was quantified in 380 attractive (148 males, 232 females) and 669 control (397 males, 272 females) healthy persons aged 4–30 years. The coordinates of 50 facial landmarks were collected by a computerized digitizer, and asymmetry computed. Soft-tissue facial asymmetries reduced as a function of age in all cases. Attractive children were more symmetric than control children, but the reverse was true for young adults. The effect of symmetry on attractiveness seems to change as a function of age.

Soft tissue facial morphometry in subjects with Moebius syndrome.

Moebius syndrome is a congenital facial palsy associated with the impairment of ocular abduction. The three-dimensional characteristics of the facial soft tissues of 12 male and 14 female subjects [3-52 yr of age (mean age + standard deviation: 17 + 14 yr)] were measured using a non-invasive, computerized system; facial volumes, areas, angles, and distances were computed and compared with those obtained in reference subjects of the same age and gender. When compared with reference subjects, patients with Moebius syndrome had a more prominent and hyperdivergent face in the sagittal plane, a smaller and more prominent upper facial third; a smaller middle facial width; a smaller nose; smaller mandibular volume, depth, corpus length, and ramus height; and a more posterior positioned mandible, with a less prominent chin. In conclusion, patients with Moebius syndrome had a tendency towards a skeletal Class II pattern. These morphological variations may be the combined effect of a general alteration of the motor and sensitive facial nerves, including the trigeminal nerve, and of a maldevelopment of the brainstem.

Facial soft-tissue volumes in adult Northern Sudanese individuals with Down syndrome

OBJECTIVE To investigate dimensions and ratios of soft-tissue facial volumes of adult Northern Sudanese subjects with Down syndrome by using computerized anthropometric measurements. DESIGN, SETTING, AND PATIENTS The 3D coordinates of soft-tissue facial landmarks were obtained by a computerized digitizer in 26 Northern Sudanese adult subjects with Down syndrome (18 men, 8 women, aged 17-34 years), and in 99 healthy Northern Sudanese controls (48 women, 51 men) of the same age range. From the landmarks, several facial volumes and volume ratios were calculated. Data were compared to those collected in healthy individuals by computing z-scores. RESULTS In subjects with Down syndrome, facial volumes were significantly smaller than in control subjects (Students t, p < 0.05). The patterns of deviation from the norm were similar in men and women. When compared to controls, subjects with Down syndrome had no differences in nose volume as a fraction of total facial volume and a larger total lip volume as a fraction of total facial volume; within the facial middle third, they had relatively larger upper lip volumes and relatively smaller nose volumes. CONCLUSIONS The facial soft-tissue structures of subjects with Down syndrome differed from those of normal controls of the same age, sex and ethnic group: a reduced facial size was coupled with specific variations in the nasal and labial regions.

Mirroring Procedures for the Assessment of Asymmetry of Different Anatomical Structures of the Cranium: A Protocol Based on 3D-3D Superimposition

The assessment of asymmetry has always represented one of the most relevant field of research in anatomy, with several applications in reconstructive and aesthetic surgery. This study aims at exposing an innovative protocol for the assessment of asymmetry of cranial structures based on 3D-3D superimposition and mirroring procedures. Five patients who underwent a head CT scan were selected. Three anatomical structures were automatically segmented through ITK-SNAP free software: maxillary sinuses, zygomatic bones and the petrous portion of both temporal bones. The left structure was then reflected automatically into the right image and superimposed over the contralateral one according to the least point-to-point distance on the entire surface. RMS (root mean square) distance was then automatically calculated for each superimposition. In addition, a chromatic map of superimposition was generated, showing the most variable areas between the two sides. Possible statistically significant differences in RMS value according to the three anatomical structures were assessed through one-way ANOVA test (p<0.05). On average, RMS values for maxillary sinuses, zygomatic bones and petrous part of temporal bones were respectively 1.00 mm (SD: 0.27 mm), 0.70 mm (SD: 0.34 mm) and 1.26 mm (SD: 0.17 mm). A significant difference among the symmetry of the three analysed structures was found (p<0.01, ANOVA). A novel approach for the assessment of anatomical asymmetry is suggested, based both on a morphological and a quantitative evaluation of differences between the right and left side skull bones.

Palatal Volume Changes in Unilateral Cleft Lip and Palate Paediatric Patients

Cleft lip and/or palate (CL/P) are the most common craniofacial abnormalities. CL/P therapy involves also orthopedic and surgical treatments. In particular, the orthopedic treatment can help to align the cleft segments and facilitate surgery. Traditionally, facial and palatal structures have been analyzed by 2D methods, omitting information of volume bone defects. A pre-surgical volume estimation can be useful to determine the anatomical boundaries of the alveolar bone defect; subsequently, volume assessments can appreciate the outcome of secondary alveolar bone grafting. In the present study, we developed a 3D stereophotogrammetric technique for volume estimation of the dental arches of children with CL/P. The method was employed to assess the 3D changes occurring in the maxillary arch of unilateral CLP (UCLP) patients with the use of plates before the first year of life. We collected 96 palatal casts of 32 neonatal patients with UCLP. Palatal casts were obtained before orthopedic treatment, before cheiloplasty, and after cheiloplasty. Half patients were treated with an active plate, half with a passive one. Casts were marked with a set of landmarks, digitized using a stereophotogrammetric system, and then analyzed. Volumes of the greater and the minor alveolar segments were separately assessed, and compared with a 3-w repeated measures ANOVA. Method accuracy was assessed using objects of known size, while repeatability was evaluated using Student’s t test and technical error of measurements. Volume estimates were accurate, without systematic errors; random errors were lower than 5% of the total variance. Significant effects of alveolar segment and time were observed (p<0.0001). Instead, no differences were found for the kind of plate. In conclusion, stereophotogrammetric systems can be a valid instrument to estimate palatal volumes of patients with CL/P during treatment, that can be followed up in a safe, rapid and non-invasive way.

ARE DENTAL MEASUREMENTS TAKEN ON PLASTER CASTS COMPARABLE TO THOSE TAKEN FROM CBCT IMAGES AND LASER SCANNED SURFACES

Introduction: Intraoral scanning techniques, laser scans and cone-beam computed tomography (CBCT) are becoming widely diffused in dental practice. These instruments can replace dental plaster casts with digital models; recent investigations have found that measurements taken on digital models do not differ clinically from those obtained on CBCT scans and physical models, but only intra-examiner reliability has been assessed. In the current study we tested both intraand inter-examiner variations, together with intertechniques reliability. Methodology: Data from six adult subjects were retrospectively obtained. Twelve dental distances were measured on dental plaster casts using a digital calliper; on digital 3D CBCT images using inVivoDental software (Anatomage, San Jose, CA); and on laser scanned surfaces using Mirror Vectra Software (Canfield Scientific, Fairfield, NJ). Two different operators performed all measurements twice. Bland-Altman analysis, Kruskal-Wallis and Wilcoxon tests were used for comparisons. Results: The intraand inter-operator biases range was 0-0.34 mm. The reproducibility range was 72-99%. The three different techniques gave very similar measurements, with biases between ±0.1 mm. Reproducibility ranged between 90 and 100%; the best reproducibility coefficients were found between plaster and digital casts, and only three differences were larger than 0.5 mm. Calliper measurements slightly overestimated digital casts values. Only the mesiodistal distance of tooth 24 (p=0.002) was significantly different among techniques. Conclusion: Measurements on digital dental models and CBCT reconstructions of the dental arches seem clinically reliable as direct calliper measurements. The interand intra-operator reliabilities were acceptable, some more care may be needed for CBCT measurements.

3D-3D facial superimposition between monozygotic twins: A novel morphological approach to the assessment of differences due to environmental factors

Distinction of one twin with respect to the other, based on external appearance, is challenging; nevertheless, facial morphology may provide individualizing features that may help distinguish twin siblings. This study aims at exposing an innovative method for the facial assessment in monozygotic twins for personal identification, based on the registration and comparison of 3D models of faces. Ten couples of monozygotic twins aged between 25 and 69 years were acquired twice by a stereophotogrammetric system (VECTRA-3D® M3: Canfield Scientific, Inc., Fairfield, NJ); the 3D reconstruction of each person was then registered and superimposed onto the model belonging to the same person (self-matches), the corresponding sibling (twin-matches) and to unrelated participants from the other couples (miss-matches); RMS (root mean square) point-to-point distances were automatically calculated for all the 220 superimpositions. One-way ANOVA was used to evaluate the differences among miss-matches, twin-matches and self-matches (p < .05). RMS values for self-matches, twin-matches and miss-matches were respectively 1.0 mm (SD: 0.3 mm), 1.9 mm (0.5 mm) and 3.4 mm (0.70 mm). Statistically significant differences were found among the three groups (p < .01). Comparing RMS values in the three groups, mean facial variability in twin siblings was 55.9% of that assessed between unrelated persons and about twice higher than that observed between models belonging to the same individual. The present study proposed an innovative method for the facial assessment of twin siblings, based on 3D surface analysis, which may provide additional information concerning the relation between genes and environment.

Comparison of direct linear measurements on dental plaster cast and digital measurements obtained from laser scanner and Cone-Beam CT dental models

Different dental imaging technologies are now daily used in clinical practice to evaluate oral anatomy. These new techniques allow to replace dental plaster casts with digital models that are easier to manage and store. Such models can be acquired with optical methods like laser scanner, stereophotogrammetry and intraoral scanner or reconstructed by 3D CT or CBCT images [1]. Since these digital casts are used in clinical routine, it is important to evaluate accuracy and reliability of measurements taken from them, in relation to traditional methods [2]. We wanted to compare linear measurements taken on digital models obtained from CBCT images and laser scanner surfaces, with direct measurements obtained with digital calliper on dental plaster casts. Data from 6 adult Caucasian subjects with full dentition, no history of implant surgery and without dental filling were obtained. The absence of implants and metal fillings was selected as inclusion criterion to reduce the presence of metal artefacts that can affect the measurement process. All patients were retrospectively selected from a clinical database and underwent CBCT examination for clinical reasons uncorrelated with this study. Six dental distances in the upper and six in the lower jaw were examined: the mesio-distal distance of teeth 21, 23, 24 and 26, the palatal-vestibular distance of teeth 24 and 26, and the corresponding distances on teeth 41, 43, 44 and 46. All measurements were performed using: 1) a digital calliper on dental plaster casts; 2) a virtual calliper on digital models obtained from CBCT images; and 3) a virtual calliper on laser scanner surfaces. Kruskal-Wallis test compared measurements performed with the 3 different techniques. There was no statistical significant difference among different techniques for all measurements (p>0.05) except for one distance, the mesio-distal distance of tooth 24 (p<0.05). Measurements on digital dental models seem as reliable as direct measurements performed on dental plaster casts. Results are promising, nevertheless further evaluation on a larger sample is advised.

Longitudinal analysis of palatal volume in unilateral cleft lip and palate children

Cleft lip and/or palate are among the most frequent congenital craniofacial defects, which every year affect one in 500-700 newborn worldwide (1,2). The aim of this study was to analyze the effect of orthopaedic and surgical treatments on the palatal size and shape of patients with unilateral cleft lip and palate (UCLP). Ninetysix palatal casts from 32 neonatal patients, attending the Fundacion Clinica de Noel (Colombia) were analyzed through a stereophotogrammetric system. The analysis was carried out before (mean age 10.5 days, SD 4.8) and after (mean age 83.3 days, SD 6.6) orthopaedic treatment (performed with acrylic plates) and after cheiloplasty (mean age 317.1 days, SD 44.2). Volumes of the greater and the minor alveolar segments were evaluated through a new measurement protocol. Intra and inter operator repeatability was evaluated using paired Student’s t test. In order to investigate differences between alveolar segments and time, volume measurements were compared with a repeated two-way analysis of variance (ANOVA). No significant differences between repetitions, both intra and inter operator, were found (p>0.05). Random errors explained 3.7% of the sample variance. On the other hand, significant differences in volume measurements were found both in alveolar segment and time (p<0.01). Before orthopaedic treatment, the smaller palatal segment had a mean volume of 0.52 cm3 (SD 0.23), and the greater of 0.9 cm3 (SD 0.40); after orthopaedic treatment, the mean volumes were 0.58 cm3 (SD 0.25), and 1.09 cm3 (SD 0.43). After surgery, mean values of 0.73 cm3 (SD 0.28) and 1.31 cm3 (SD 0.52) were measured. Results suggest that a three-dimensional stereophotogrammetric system is a repeatable and reliable method to evaluate palatal casts of patients with UCLP. Obtained data offer a preliminary quantitative information about the changes occurring in maxillary arches of UCLP patients after orthopaedic treatment and surgery. Further investigation is required to increase the frequency of evaluations and the number of patients.

Gender- and age-related changes in three dimensional facial profiles of healthy Northern Sudanese persons

The study aimed to provide quantitative information about gender-related normative data and growth changes between childhood and young adulthood in the soft tissue facial profiles of Northern Sudanese individuals. The three dimensional coordinates of 50 landmarks on the facial soft tissues were obtained using a hand-held laser scanner in 654 healthy Northern Sudanese subjects (327 males and 327 females) aged 4-30 years. The subjects were divided into 8 nonoverlapping age groups [1]. From selected landmarks, 15 facial angles were calculated and averaged for gender and age: upper, middle, and lower facial, and mandibular corpus convexities in the horizontal plane; relative position of the exocanthia and nasion; facial convexity in the sagittal plane; midfacial to mandibular plane, nasal convexity, nasolabial, mentolabial, interlabial, maxillary prominence, and left and right gonial angles. Comparisons were performed by factorial analysis of variance. On average men had larger facial and mandibular corpus convexities in the horizontal plane than women (ANOVA, p<0.01); on the contrary, no gender differences were found for facial convexities in the sagittal plane. Gender significantly influenced also the relative position of exocanthia and nasion, the maxillary prominence angle and the gonial angles (p<0.01). All analysed measurements were influenced by age (p<0.001): nasal convexity and interlabial angle increased from childhood to young adulthood, while mentolabial and gonial angles, horizontal facial convexity and sagittal facial convexity including the nose decreased as a function of age. No consistent age-related patterns were found for the other evaluated angles. Data collected in the current study can be used as a database for the quantitative description of facial profiles in Northern Sudanese subjects during normal growth and development.