Marcio De Menezes

Accuracy and Reproducibility of a 3-Dimensional Stereophotogrammetric Imaging System

PURPOSE To test the accuracy and reproducibility of a 3-dimensional (3D) stereophotogrammetric imaging system for measuring the facial soft tissues of healthy subjects. MATERIALS AND METHODS Three-dimensional soft tissue facial landmarks were obtained from the faces of 10 adult subjects, by use of a 3D stereophotogrammetric imaging system (Vectra; Canfield Scientific, Fairfield, NJ). Sixteen linear measurements were computed. Systematic and random errors between operators, calibration steps, and acquisitions were calculated. RESULTS No systematic errors were found for all performed tests (P > .05, paired t test). The method was repeatable, and random errors were always lower than 1 mm, except for the distance from cheilion to cheilion. Repeated sets of acquisition showed random errors up to 0.91 mm, without systematic biases. CONCLUSION The 3D stereophotogrammetric imaging system can assess the coordinates of facial landmarks with good precision and reproducibility. The method is fast and can obtain facial measurements with few errors.

Digital dental cast placement in 3-dimensional, full-face reconstruction: A technical evaluation

INTRODUCTION Several noninvasive methods are used for 3-dimensional (3D) morphologic facial and dental analysis to aid practitioners during diagnosis and treatment planning. Integrating dental and facial noninvasive 3D reproduction could improve the efficacy of treatment management. METHODS Dental virtual model and soft-tissue facial morphology were digitally integrated from 11 adults with a 3D stereophotogrammetric imaging system (Vectra, Canfield Scientific, Fairfield, NJ). The digital 3D coordinates of 3 facial landmarks (N, nasion; Ftr, frontotemporale right; Ftl, frontotemporale left) and 3 dental landmarks (I, interincisor; Pr, PI, tips of the mesiovestibular cusps of the right and left first permanent premolars) were then obtained by using Vectras software. Additionally, the coordinates of the same 6 landmarks were digitized directly on each subject by using a 3D computerized electromagnetic digitizer (in vivo). Seven linear measurements were made between the occlusal plane (Pr-I-Pl) and the facial landmarks (Ftr-N-Ftl). The accuracy and reliability of the reconstruction were tested by in-vivo measurements and repeated acquisitions. RESULTS The greatest mean relative error of measurements was smaller than 1.2%. No significant differences in repeatable reproductions were found. CONCLUSIONS Integration of facial stereophotogrammetry acquisition and dental laser scan reproduction is possible with marginal error.

Age- and sex-related changes in the normal human external nose

The objective of this study was to measure: (1) normal sex-related dimensions of external nose (linear distances, ratios, angles, volume and surface area); and (2) growth changes between childhood and old age. The three-dimensional coordinates of several soft-tissue landmarks on the external nose were obtained by a non-invasive, computerized digitizer in 519 male and 340 female healthy subjects aged 4-73 years. The subjects were divided into 11 non-overlapping age groups: for children and preadolescent subjects, 2-year spans were used, while larger intervals were used for adolescent and adult subjects. From the landmarks, nasal volume and external surface area; nasal and alar base widths, nasal height, nasal bridge length, philtrum length, nasal tip protrusion, right and left nostril lengths, superior and inferior nostril widths; nasal tip protrusion-to-nasal height, and nasal width-to-nasal height ratios; nasal convexity, alar slope, and nasal tip angles were calculated, and averaged for age and sex. Comparisons were performed by factorial analysis of variance. On average, men had larger nasal external volume and area, linear distances and nasal width-to-height ratio than women (p<0.01); no sex differences were found for the angles and the nasal tip protrusion-to-nasal height ratio. Age significantly influenced all analyzed measurements (p<0.001): nasal volume, area, linear distances increased from childhood to old age, while the nasal tip angle decreased as a function of age. No consistent age related patterns were found for the ratios and the nasal convexity and alar slope angles. Men and women had different age related patterns, with significant sex by age interactions (p<0.001). Overall, in most occasions male increments in nasal dimensions were larger than female ones. Data collected in the present investigation could serve as a database for the quantitative description of human nasal morphology during normal growth, development and aging. Forensic applications (evaluations of traumas, craniofacial alterations, teratogenic-induced conditions, facial reconstruction, aging of living and dead persons, personal identification) may also benefit from age and sex based data banks.

Age- and sex-related changes in three-dimensional lip morphology

The objective of this study was to supply information about: (1) normal sex-related dimensions of mouth and lips (linear distances, ratios, angles, area, volume); and (2) growth changes between childhood and old age. The three-dimensional coordinates of several soft-tissue landmarks on the lips and face were obtained by a non-invasive, computerized electromagnetic digitizer in 532 male and 386 female healthy subjects aged 4-73 years. From the landmarks, linear distances (mouth width, width of the philtrum, vermilion heights of the upper, lower and total lips, total lip height), the vermilion height-to-mouth width ratio, areas (vermilion of the upper, lower and total lip) and volumes (upper, lower, and total lip volume) were calculated and averaged for age and sex. Comparisons were performed by factorial analysis of variance. Mouth width, width of the philtrum, total lip height, and lip volumes were significantly larger in men than in women (p<0.01), increased with age (p<0.001), and had age x sex interactions (p<0.001). Vermilion areas and heights of the lower and total lips progressively increased with age until late adolescence, and then decreased with aging (p<0.001). The vermilion height-to-mouth width ratio was larger in women than in men (p<0.001), and decreased with age (p<0.001). Data collected in the present investigation could serve as a database for the quantitative description of human lip morphology during normal growth, development and aging. Forensic applications (evaluations of traumas, craniofacial alterations, teratogenic-induced conditions, facial reconstruction, aging of living and dead persons, personal identification) may also benefit from age- and sex-based data banks.

A Photographic System for the Three-Dimensional Study of Facial Morphology

OBJECTIVES To test whether digital photographs supported by three-dimensional (3D) software are suitable for measuring the facial soft tissues of healthy subjects as compared with data obtained by a certified 3D computerized electromagnetic digitizer. MATERIALS AND METHODS Three-dimensional soft tissue facial landmarks were obtained from the faces of 15 healthy young adults, using a 3D computerized electromagnetic digitizer and a new low-cost photogrammetry system. Twelve linear and 18 angular measurements were computed. Errors between methods and repeatability of the new method were calculated. RESULTS Systematic errors between methods were found for only two distances and three angles (paired t-test, P < .05). The mean absolute differences between methods were always lower than 3 mm and 3 degrees. Repeated digitization of photographs showed that the method was repeatable (no systematic differences; random errors lower than 1.6 mm and 3 degrees). Repeated sets of photographs showed random errors of up to 5.3 mm and 5.6 degrees, without systematic biases. CONCLUSION The 3D photogrammetry system can provide reliable facial measurements. The method is relatively fast and requires only inexpensive equipment. It is simple to use for private practice, research, or other practice.

Morphometry of the ear in north Sudanese subjects with Down syndrome: a three-dimensional computerized assessment.

Down syndrome (DS) is the most frequent live-born autosomal aneuploidy in humans. Scanty data on the craniofacial phenotype of African subjects with DS have been published so far. We wanted to detail the morphologic characteristics of the ears in north Sudanese subjects with DS.The three-dimensional coordinates of 13 soft-tissue landmarks on the ears were obtained using a laser scanner in 64 north Sudanese subjects with DS aged 4 to 34 years and in 682 sex- and age-matched control subjects. From the landmarks, left and right linear distances (ear width and length), ratios (ear width-to-ear length), areas (ear area), angles (angle of the auricle vs the facial midplane), and the three-dimensional symmetry index were calculated. Distances, angles, areas, and ratios were computed. Subject and reference data were compared by computing z scores and calculating Student t tests. Ear width, length, and area were significantly (Student t test, P < 0.001) smaller in the subjects with DS than in the reference subjects. On the right side of the face, the subjects with DS had larger ear width-to-ear length ratios and larger angles of the auricle versus the facial midplane than the reference subjects. The three-dimensional symmetry index was significantly larger in the reference subjects. In conclusion, ear dimensions, position, and shape significantly differed in subjects with DS when compared with sex-, age-, and ethnic group-matched control subjects.

The occlusal plane in the facial context: inter-operator repeatability of a new three-dimensional method

The repeatability of a non-invasive digital protocol proposed to evaluate the three-dimensional (3D) position of the occlusal plane in the face is assessed. Dental virtual models and soft tissue facial morphology of 20 adult subjects were digitally integrated using a 3D stereophotogrammetric imaging system. The digital 3D coordinates of facial and dental landmarks were obtained by two different operators. Campers (facial) and occlusal (dental) planes were individuated, and their 3D relationships were measured. The repeatability of the protocol was investigated and showed no significant differences in repeated digitizations. The angle between occlusal and Campers planes was smaller than 2° in the frontal and horizontal projections. In the sagittal projection, the angle was observed to be, on average, 4.9°. The determined occlusal plane pitch, roll and yaw values show good agreement with previously published data obtained by different protocols. The current non-invasive method was repeatable, without inter-operator differences and can facilitate assessment of healthy subjects.

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.

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.

Longitudinal morphometric analysis of dental arch of children with cleft lip and palate: 3D stereophotogrammetry study

OBJECTIVE This study aimed to perform a longitudinal morphometric analysis of the alterations of the maxillary dental arches in children with cleft lip and palate before and after primary lip and/or palate surgeries using a 3-dimensional stereophotogrammetry system. STUDY DESIGN The sample consisted of dental casts of 60 children with complete unilateral cleft lip (UCL) and complete unilateral cleft lip and palate (UCLP). Dental arches were evaluated before cheiloplasty (T1), after cheiloplasty (T2), and 1 year after palatoplasty (T3). Independent t test and Mann-Whitney U test were used for intergroup comparisons, and paired t test, Wilcoxons test, and repeated-measures analysis of variance (ANOVA), followed by Tukeys test, were used for intragroup comparisons. RESULTS At T1, the intercanine and intertuberosity distances in the UCLP group were statistically greater than those in the UCL group. At T2, the maxillary dimensions significantly increased, except for the intertuberosity distance in UCL. Between T1 and T3, the intercanine distance and the anterior length decreased significantly, whereas the intertuberosity distance and the total length of the palate increased significantly. CONCLUSIONS Our results indicated that the primary lip surgery altered the development of dental arches, evidently in children with UCLP. The primary palate surgery interfered in the growth of the anterior palatal region in the UCLP group. Children with UCLP had more restricted development of the maxillary dental arch compared with children with UCL.