Biomedical subjects

C Sforza

Publications and source records attributed to C Sforza.

At least 91 records · Page 5Linked to original sources

PubMed1994

Distance from symmetry: a three-dimensional evaluation of facial asymmetry.

PURPOSE: A new method for the quantification of facial asymmetry has been developed and applied to a group of 80 young, healthy, white adults with no craniofacial, dental, or mandibular disorders. The method calculates an asymmetry vector (distance from the symmetry) that allows both the quantification of the absolute degree of asymmetry and its three-dimensional direction and verse. METHODS: For each subject, the three-dimensional coordinates of 16 standardized soft-tissue facial landmarks (trichion, nasion, pronasale, subnasale, B point, pogonion, eye lateral canthi, nasal ala, labial commissure, tragus, gonion) were automatically collected using a noninvasive instrument. The coordinates underwent a four-step analysis: 1) calculation of the plane of symmetry, the facial centers of gravity, and the asymmetry vector in each subject; 2) calculation of the mean absolute asymmetry in each sample; 3) calculation of the mean asymmetry vector (resultant vector) in the population; and 4) calculation of the separate contributions of the single facial structures to the facial asymmetry. RESULTS: A certain degree of soft-tissue facial asymmetry was found both in the individuals and in the global population, and it was evident especially in the middle (tragus) and lower (gonion) thirds of the face. The right side of face was larger than the left side.

Adult↗

PubMed1994

Head posture and cephalometric analyses: an integrated photographic/radiographic technique.

A photographic technique for natural head posture (NHP) recording that can be associated to standard radiographic exposures is presented. It allows the evaluation of radiographs, according to both the standard intracranial references and NHP. On the NHP photograph, the angle between the soft tissue nasion-pogonion line and the true vertical is calculated, and this value is used to rotate the standard radiograph around the Bolton point. The technique has been applied to 40 private orthodontic patients (24 females and 16 males, aged 7 to 20 years, mean 12.9 years). The hard tissue Frankfurt plane in NHP showed a wide variation: 80% of the patients had orbitale lower than porion (mean angle -6 degrees relative to the ground), 20% had orbitale higher than porion (mean angle 4 degrees). The position of this plane in NHP seemed to be different in the two sexes, with more males having the Frankfurt plane going upwards than females. The soft tissue Frankfurt plane (tragus-orbitale) in NHP was directed upwards (head extended) in 53% of patients. The two Frankfurt planes were never coincident in all subjects; the tragus was always lower and more anterior than porion. On average, the angle tragus-orbitale-porion was about 6 degrees. In young orthodontic patients NHP is therefore highly variable, gender dependent, and cannot be deduced from mean population values. Nevertheless, the evaluation of head position should be performed in each young patient before and during the treatment, to verify how the combined effects of therapy and growth act.

Adolescent↗

PubMed1994

Mathematical definition of the shape of dental arches in human permanent healthy dentitions.

Dental arch shape was studied in 50 men and 45 women aged 20-27 years with sound dentitions. Maxillary and mandibular arches were reconstructed by a fourth-order polynomial and a 'mixed' elliptical (anterior teeth), plus parabolic (post-canine teeth) interpolation of buccal cusp tips (central incisor to second molar). The maxillary arch resulted wider than the mandibular arch regardless of gender. Gender differences were found especially in the maxillary arch, where they reflect more a size discrepancy than a shape difference. The polynomial interpolation allowed the evaluation of arch asymmetry, which resulted negligible in all the subjects. The elliptical plus parabolic interpolation gave mean plots which were well superimposable to the ones obtained by the polynomial interpolation. These curves are geometrically simple and can be used for the mathematical description of dental arch shape in non-patient subjects. Moreover, they allow separate analysis of teeth with a different functional meaning.

Adult↗

PubMed1994

Shape of the human corpus callosum. Elliptic Fourier analysis on midsagittal magnetic resonance scans.

RATIONALE AND OBJECTIVES: Sex, age, or functional-asymmetry-related variations in the size and shape characteristics of the midsagittal magnetic resonance (MR) image of the human corpus callosum (CC) have been widely investigated in the last 10 years, with conflicting results. In the current study, the authors attempted to analyze the sex- and age-related shape differences of the human CC in a large sample of adult subjects from a mathematical standpoint. METHODS: On the midsagittal MR images of 143 neurologically intact adults (75 women, 68 men, 21 to 81 years of age) the outline of the CC was identified. The shape of the CC was quantified using elliptic Fourier analysis, which allows for a global evaluation of the shape of organs identified by their outlines independent of their size, spatial orientation, and relation to reference planes. Subjects were grouped by sex and age. RESULTS: The shape of the human CC within age and sex class was highly variable. The analysis of variance showed a significant effect of age; however no significant sex differences could be demonstrated. CONCLUSIONS: Larger sample sizes are required to definitively assess the normal shape variations in human CC. The method developed also could be applied to the comparison of healthy and diseased individuals.

Adult↗

PubMed1994

A three-dimensional study of sexual dimorphism in the human face.

The sexual dimorphism in three-dimensional facial form (size plus shape) was investigated in a sample of 40 men and 36 women by using Euclidean-distance matrix analysis. Subjects ranged in age from 19 to 32 years, had excellent dentitions, and had no craniocervical disorders. For each subject, 16 facial landmarks were automatically collected using a computerized system consisting of two infrared CCD cameras, real-time hardware for the recognition of markers, and software for the three-dimensional reconstruction of landmarks' x, y, z coordinates. Euclidean-distance matrix analysis confirmed the well-known size difference between adult male and female faces (men's faces being 6% to 7% larger than women's faces), while it demonstrated no significant gender differences in three-dimensional facial shape. This result contrasted with the shape differences previously found when separate two-dimensional frontal and sagittal plane projections were analyzed. It could be explained by a relative three-dimensional compensation between the different facial dimensions.

Adult↗

PubMed1994

Comparison of soft tissue facial morphometry in children with Class I and Class II occlusions.

Three-dimensional soft tissue facial morphometry was investigated in a sample of 167 children aged 6 to 9 years by using a new noninvasive computerized method. For each child, 16 cutaneous facial landmarks were automatically collected by a system consisting of two infrared CCD cameras, real-time hardware for the recognition of markers, and software for the three-dimensional reconstruction of the x, y, and z coordinates of landmarks. From these landmarks, 15 linear and 10 angular measurements and five linear distance ratios were computed. For each age class, mean values were computed for all children with a bilateral Angle Class I occlusion (modified according to Katz) and compared with values obtained in children with a bilateral Class II occlusion. Most of the differences involved three-dimensional angular measurements: Class II children had more convex faces in the sagittal plane and a less prominent mandible than did Class I children. No differences were found in the linear measurements. Only the lower facial height ratio was different between the two occlusion groups, but the difference was not consistent among all the age groups.

Cephalometry↗

PubMed1993

Human dental arch shape evaluated by euclidean-distance matrix analysis.

Form differences between biological structures can be evaluated using several approaches. When landmark data are available, a recently proposed method (euclidean-distance matrix analysis) seems to be able to differentiate between size and shape differences. This method also localizes those areas which differ most between the two structures. We have applied it to analyze the sexual dimorphism in dental arch form in a sample of 50 men and 45 women. Subjects ranged in age between 20 and 27 years, and had sound dentitions. Fourteen landmarks, corresponding to the centers of gravity (centroids) of the occlusal surfaces of all permanent teeth (right second molar to left second molar), were individualized on the dental casts of subjects. All the possible linear distances between pairs of teeth were computed, thus creating four mean form matrices (one for each arch within sex). Gender differences were tested by using euclidean-distance matrix analysis. No significant differences were demonstrated in the shape of arches, while male arches proved to be slightly bigger than female arches.

Adult↗

PubMed1993

Morphometric study of the human ovary during compartmentalization.

The volumetric composition of the human ovary during the compartmentalization stage has been investigated using current stereological methods. Eight left ovaries removed from three fetuses (developmental age 20-25 weeks), four neonates, and one 8-month-old child all with a 46,XX karyotype, free from malformations of the genital apparatus, were completely cut obtaining serial sections and one 1 micron-thick section every 1,000 microns was examined. Ovarian volume was 30 mm3 at the 20th week of development, 36 mm3 at the 25th week, 129 mm3 at birth, and 287 mm3 at the eighth postnatal month. The primitive cortical tissue was the largest component of the fetal ovaries (17 mm3, corresponding to 60.2% of the organ). The second component was the interstitium (21% of the organ), followed by the medulla (11.8% of the organ). The primordial follicles occupied a small part of the organs: 1.8 mm3 at 20 weeks and 3.4 mm3 at 25 weeks (respectively 6.7% and 5.4% of the volumes of the relevant ovaries). At birth, most of the organ was composed of interstitial tissue (57 mm3, 44.2% of the volume) followed by the medulla (25 mm3, 20.3% of the volume). The germinal tissue occupied 46 mm3, mainly primitive cortical tissue (14.9% of the ovary) and primordial follicles (16.3% of the ovary), with a minor contribution from the antral follicles (about 3% of the ovary).(ABSTRACT TRUNCATED AT 250 WORDS)

Female↗

PubMed1993

Dental arch asymmetry in young healthy human subjects evaluated by Euclidean distance matrix analysis.

Form differences between biological structures can be evaluated using several approaches. A recently proposed method (Euclidean distance matrix analysis; EDMA) seems to be able to differentiate between size and shape differences. Here it has been applied to study the asymmetry of mandibular and maxillary arches in 50 men and 45 women with sound dentitions. The centres of gravity (centroids) of the occlusal surfaces of all permanent teeth (right second molar to left second molar) were individualized on the dental casts of subjects. The form of the right and left maxillary and mandibular hemi-arches was separately assessed by calculating all the possible linear distances between pairs of teeth within arch and side. Side differences were tested by EDMA. In men, the maxillary and the mandibular arches were both symmetrical (i.e. there were no significant differences in size or shape between the left and right hemi-arches). In women, the mandibular arch was symmetrical, but in the maxillary arch the two antimeres had a significantly different shape. No size differences were found between the left and right female hemi-arches.

Adult↗

PubMed1993

Craniofacial morphometry by photographic evaluations.

Frontal and lateral oriented profile photographs of 108 healthy young adults (57 men and 51 women) were taken, and a standardized protocol was used to quantitatively describe the depicted craniofacial soft tissue structure, the relationships among facial structures, and head posture relative to the ground. Pictures were taken in two body positions, standing and sitting. The male faces were, on average, wider and longer than the female faces, in both frontal and lateral views, with greater differences in the mouth and chin regions. Both sexes were generally symmetrical. Persons who were asymmetric compensated for their appearance by changing head posture relative to the ground, so that in the frontal plane, the interpupillary axis and the occlusal plane were parallel to the ground. Measurements can be employed in computer graphic reconstructions used in orthognathic, maxillofacial, and plastic surgery. In the standing position, the Frankfurt plane was directed upward and forward, with a mean angle of 13 degrees relative to the ground. In seated subjects, it was more nearly horizontal (5 degrees in the men, 8 degrees in the women). This result confirms the need for a careful reevaluation of standard cephalometric and photographic protocols.

Adult↗

PubMed1993

Electromyographic activity of human masticatory muscles in normal young people. Statistical evaluation of reference values for clinical applications.

Electromyographic activity of anterior temporal and masseter muscles was measured in 92 young healthy men and women with sound dentitions during rest position, contact in centric occlusion and clench. Male and female mean potentials were similar except in clench, where males had higher electromyographic levels. Mean pooled electromyographic potentials were 1.9 microV (TA) and 1.4 microV (MM) during rest position, 6.5 microV (TA) and 2.8 microV (MM) during contact in centric occlusion. Mean maximum voluntary clench potentials were 181.9 microV (TA) and 216.2 microV (MM) in men, 161.7 microV (TA) and 156.8 microV (MM) in women. Examined muscles were more asymmetric at low electromyographic activity (rest and centric occlusion) with the temporal muscle less asymmetrical than the masseter. In females temporal muscle activity tended to dominate at every contraction level, while in males masseter activity was stronger in clench, and temporal activity in centric occlusion and in rest position.

Adult↗

PubMed1993

Position and asymmetry of teeth in untreated dental arches.

The position and asymmetry of all permanent teeth (right second molar to left second molar) were studied in 50 men and 45 women aged 20 to 27 years with sound dentitions. The centers of gravity of the occlusal surfaces of teeth were individualized on dental casts. The maxillary arch distances between homologous teeth were all larger than the mandibular arch distances regardless of gender. Arches in women were found to be significantly smaller than arches in men. On average, arches were symmetric with mean indexes ranging from 0.28% to 4.57%. Results demonstrated that a certain degree of morphological asymmetry may be considered a normal finding.

Adult↗

PubMed1993

Human neonatal ovary: proposal of a three-dimensional model.

A model of human neonatal ovary is presented, derived from morphometric, evaluations carried out on left ovaries removed from five full-term neonates with a 46, XX karyotype, free from malformations of the genital apparatus. According to this model, the gonad can be represented by a triaxial ellipsoid with a central medullary core surrounded by a cortical stratum of constant thickness. The germinal population, consisting of follicles and primitive cortical tissue, occupies the cortex, intermingled with the interstitium or stroma. In the cortex it is then possible to describe an outer layer formed by primitive cortical tissue, and an inner portion occupied by follicles. The primary and secondary follicles fill the portion near the medulla and the primordial ones are contained in the middle and outer zones. Since the variability observed among ovaries is slight, we can propose a mean model of neonatal ovary in which the spatial relationships among the different components, the total number of follicles and their position in the cortex can be calculated.

Female↗

PubMed1993

Sexual dimorphism in the human face assessed by euclidean distance matrix analysis.

The form of any object can be viewed as a combination of size and shape. A recently proposed method (euclidean distance matrix analysis) can differentiate between size and shape differences. It has been applied to analyse the sexual dimorphism in facial form in a sample of 108 healthy young adults (57 men, 51 women). The face was wider and longer in men than in women. A global shape difference was demonstrated, the male face being more rectangular and the female face more square. Gender variations involved especially the lower third of the face and, in particular, the position of the pogonion relative to the other structures.

Adult↗

PubMed1993

ANB skeletal types correlated to facial morphology: Euclidean distance matrix analysis.

Pretreatment lateral skull radiographs of 145 patients aged 7 to 20 years are classified according to an ANB-angle reading corrected for the position of the maxilla and rotation of the jaw. The Euclidean distance matrix analysis is applied to compare the overall facial morphology between Classes I and II. This method differentiates between size and shape and localizes those areas that differ the most. Statistically significant different facial morphologies were demonstrated in the 32 patients aged 15 years or more. The younger patients with skeletal Classes I and II did not possess these different morphological characteristics. The results show that standard cephalometric classification criteria do not always correlate to actual differences in the overall facial morphology.

Adolescent↗

PubMed1992

Mathematical definition of the curve of Spee in permanent healthy dentitions in man.

The intrinsic morphology of the mandibular curve of Spee (i.e. independent from reference planes) was studied in 50 men and 45 women with sound dentitions. Left and right curves were reconstructed by a second-order quadratic interpolation of buccal cusp tips. Gender differences were found in both sides, while side differences were found only in the male sample. Male and female curves had similar concavities, but the position of the interpolating second-order quadratic curve relative to the dental arch was significantly different. The right and left male sides showed different concavities, the right-hand side being flatter than the left. Male curves appeared larger than female ones, and the left-hand side was significantly larger than the right regardless of gender. The reported second-order quadratic curves could be used as reference for prosthetic and orthodontic reconstructions.

Adult↗

PubMed1992

Biomechanical model of the human mandible: a hypothesis involving stabilizing activity of the superior belly of lateral pterygoid muscle.

A new biomechanical analog for the human mandible is proposed. The biomechanics of the human mandible can be explained by a simple support model, where muscular forces are produced by the masseter, medial pterygoid, temporal, and superior lateral pterygoid muscle components, and reaction forces are produced by the occlusal surfaces and condyle. All forces are resolved into components orthogonal and parallel to the temporal articular plane (articular eminence). In this model, one component of muscular forces is parallel to the temporal articular plane. The influence of the inclination of the occlusal plane, the inclination of the temporal articular plane, the position of the resultant of the occlusal reactions, and the relative contribution of the different jaw elevator muscles on the parallel and orthogonal components are evaluated according to a computer model of the system. The muscular force parallel to the temporal articular plane may be produced by the superior lateral pterygoid muscle, which during clenching acts as a stabilizer of the mandibular condyle to prevent posterior dislocation and compression of nonarticular tissues.

Biomechanical Phenomena↗

PubMed1992

Kinesiographic three-dimensional evaluation of mandibular border movements: a statistical study in a normal young nonpatient group.

Mandibular border movements were studied in a group of 74 healthy young men and women with sound dentitions and class I molar relationships. Movements were directly performed by the subjects and recorded with a mandibular kinesiograph, and slopes of the first millimeters of motion in the anterior and lateral guidances were calculated. In anterior guidance, the sagittal plane slope was steeper in men than in women, whereas the horizontal plane slope showed no gender differences. In the lateral guidances, frontal plane slopes were steeper in men than in women, with no side differences. The horizontal plane slope presented no side or sex differences. Most of the subjects demonstrated asymmetric guidances for both protrusive and the laterotrusive movements. These findings suggest that criteria for defining the norm should include asymptomatic asymmetry instead of strict morphologic symmetric appearance.

Adult↗