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Biomedical subjects

C Sforza

Publications and source records attributed to C Sforza.

At least 73 records · Page 4Linked to original sources
PubMed1996

Occlusion and center of foot pressure variation: is there a relationship?

The influences of head and body posture on the mandibular rest position, the range of functional movements, and the initial tooth contact have been documented. In this investigation, the modifications of the position of the center of foot pressure during natural standing were studied in 30 women. The subjects were divided into three groups: healthy women (control), women with an asymmetric (unilateral) Angle class II malocclusion, and women with temporomandibular disorders. Data were acquired in 30-second trials by use of a force plate that allowed a separate assessment of each foot while the subjects maintained different dental positions: rest position; centric occlusion; maximum clench; occlusion on two cotton rolls placed on the mandibular teeth distal to the canines; and maximum clench on two cotton rolls. Bivariate analysis was used to compute the mean values and relevant variability for the center of foot pressure location during each trial. The results demonstrated that the modifications of foot center of pressure were not influenced by temporomandibular disorders and asymmetric malocclusion or by different dental positions.

Adult↗
PubMed1996

Temporomandibular joint dysfunction and flat lateral guidances: a clinical association.

Temporomandibular joint alterations have been associated with abnormal mandibular movements in the open/close cycles and in the laterotrusive border movements. The quantitative analysis of these movements could allow a better or earlier diagnosis for patients and offer some insight into the pathophysiology of the disorder. Maximum opening and mandibular laterotrusive border movements were studied and measured in a group of 165 patients with a considerable lateral deviation (equal to or greater than 5mm) in maximum opening. Movements were directly performed by the patients and recorded with a mandibular kinesiography. The slope of the lateral guidance (frontal plane projection) was measured in the first millimeters of motion and started from the maximum intercuspal position. On average, slopes were significantly flatter on the same side with the opening deviation. These slopes were significantly flatter than previously published physiologic ranges, whereas contralateral slopes were similar to normal references. The results may be explained by a correlation between the insufficient lateral protection and a temporomandibular mandibular joint dysfunction (ipsilateral low mobility).

Adult↗
PubMed1996

Assessment of facial form modifications in orthodontics: proposal of a modified computerized mesh diagram analysis.

A modified computerized mesh diagram analysis enables rapid, easy, and independent quantifications of facial size, shape, and head position. A lateral cephalometric radiograph is traced, positioned in natural head position (NHP) according to the NHP registered on a lateral photograph, and superimposed by the standard grid of rectangles determined by the patient's upper face height and face depth. The patient's tracing is compared with a reference tracing of a norm. The two tracings are registered at nasion in NHP, and the size difference of the patient's mesh rectangles from the norm is quantified by a size normalization. The shape discrepancies are evaluated by calculating relevant displacement vectors for each cephalometric landmark, and a global difference factor. This computerized method provides a rapid graphic evaluation of the patient's sagittal and vertical discrepancies and can also be applied to determine the effects of orthodontic therapy and/or growth on the skeletal and dental relationships in a single patient.

Adolescent↗
PubMed1996

Facial three-dimensional morphometry.

Three-dimensional facial morphometry was investigated in a sample of 40 men and 40 women, with a new noninvasive computerized method. Subjects ranged in age between 19 and 32 years, had sound dentitions, and no craniocervical disorders. For each subject, 16 cutaneous facial landmarks were automatically collected by a system consisting of two infrared camera coupled device (CCD) cameras, real time hardware for the recognition of markers, and software for the three-dimensional reconstruction of landmarks' x, y, z coordinates. From these landmarks, 15 linear and 10 angular measurements, and four linear distance ratios were computed and averaged for sex. For all angular values, both samples showed a narrow variability and no significant gender differences were demonstrated. Conversely, all the linear measurements were significantly higher in men than in women. The highest intersample variability was observed for the measurements of facial height (prevalent vertical dimension), and the lowest for the measurements of facial depth (prevalent horizontal dimension). The proportions of upper and lower face height relative to the anterior face height showed a significant sex difference. Mean values were in good agreement with literature data collected with traditional methods. The described method allowed the direct and noninvasive calculation of three-dimensional linear and angular measurements that would be usefully applied in clinics as a supplement to the classic x-ray cephalometric analyses.

Adult↗
PubMed1996

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

RATIONALE AND OBJECTIVES: The authors previously investigated the midsagittal magnetic resonance images of neurologically intact adults, and analyzed the shape of corpus callosum from a mathematic standpoint. Significant effects of age were demonstrated, without significant sex differences. In the current study, the same mathematic method was applied to analyze the sex and age shape differences of the human corpus callosum in childhood. METHODS: On the midsagittal magnetic resonance images of 84 neurologically intact children (39 boys, 45 girls, aged 4 months to 15 years) the outline of the corpus callosum was identified. Its shape was quantified using elliptic Fourier analysis, which allows for global evaluation of the shape of organs identified by their outlines independently from size, spatial orientation, and relationship to reference planes. Subjects were grouped by sex and age. RESULTS: The shape of the corpus callosum within age and sex classes in childhood was more homogeneous than in adulthood. A significant effect of age was demonstrated by the analysis of variance; however, no significant sex differences were found. CONCLUSIONS: Corpus callosum shape in midsagittal magnetic resonance images was strongly influenced by central nervous system development and aging, but the influence of sex was not sufficient to be detected by current standard magnetic resonance imaging technology, and by the available sample sizes. The current investigation supplies data on the normal callosal shape in the first two decades of life, thus completing previous analysis.

Adolescent↗
PubMed1996

Open-close movements in the human temporomandibular joint: does a pure rotation around the intercondylar hinge axis exist?

Mandibular movements near the maximum intercuspal position were analysed for the location of the mean instantaneous centre of curvature of the interincisal point path. Measurements were performed using a kinesiograph in 28 healthy young adults with sound dentitions and free from temporomandibular joint disorders. The subjects performed habitual open-close cycles at different speeds; opening movements starting from the centric relation occlusion were also analysed. In none of the 28 subjects was the interincisal point path derived from pure rotation movements performed around the intercondylar axis, not even in the first millimetres of motion. Translation and rotation were always combined, and the position of the centre of curvature changed during the motion, showing different characteristics in the open and close movements; these patterns were also dependent upon motion speed. The results show that the hinge axis theory cannot explain the mandibular movements because a pure rotation did not occur around the intercondylar axis.

Adult↗
PubMed1996

Fourier analysis of cephalometric shapes.

Craniofacial growth and development involve both size and shape variations. Shape variations can be assessed independently from size using mathematical methods such as the Fourier series. A method for the reconstruction of outlines starting from selected landmarks and for their Fourier analysis has been developed and applied to analyze the age differences in shape in the tracings of the Bolton standards (lateral view) from 1 to 18 years of age. The size-independent shape of the Bolton standard at 18 years was larger at the chin, at the gonion, and in the anterior cranial base than the shape at 1 year of age. Conversely, the younger shape was larger in the middle part of face, corresponding roughly to the maxillary bone, than the older shape. When standardized for size, growth thus seemed to modify craniofacial shape with progressive lengthening and narrowing. This shape effect was largely overwhelmed by the very evident size increments, and it could be measured only using the proper mathematical methods.

Adolescent↗
PubMed1996

Effect of growth and development on human soft tissue facial shape: a Fourier analysis.

Size plays a distorting role in the estimation of facial morphology, because it can mask more subtle shape differences. The conventional metric approach provides adequate quantitative information about size only, ignoring the problems of shape definition. Mathematical methods, such as the Fourier series, allow a correct quantitative analysis of shape and its changes. Methods to reconstruct outlines, starting from selected landmarks, and to allow Fourier analysis of these outlines have been developed. These techniques were applied to analyze the age and gender variations in shape of the soft tissue facial contour (frontal plane projection) in a group of 144 healthy children, aged 6 to 7 years and 9 to 10 years. The mean contours differed for both size and shape; Fourier analysis corrected for the size discrepancy and separated the contributions of size and shape to the global morphology. In particular, the sine component (asymmetry) of the soft tissue facial contour was influenced by both age and gender.

Cephalometry↗
PubMed1996

Three-dimensional facial morphometry and conventional cephalometrics: a correlation study.

The purpose of this study was to compare the correlation between three-dimensional soft tissue measurements obtained with three-dimensional digital infrared photogrammetry and two-dimensional data obtained with conventional cephalometry. Facial morphometry was investigated in a group of 20 healthy young men using both systems on each subject. From the lateral radiographs, conventional two-dimensional cephalometric hard and soft tissue data were calculated, while three-dimensional linear and angular soft tissue measurements were computed from the infrared photogrammetry. The correlations between the two sets of measurements were calculated. Three-dimensional soft tissue measurements correlated to cephalometric data primarily contained information useful for esthetic analysis. The soft tissue infrared measurements also allowed evaluation of the general hard tissue situation. Since the soft tissue measurements are calculated with a noninvasive system, they could be computed more frequently during treatment and be used to supplement pretreatment and posttreatment radiographs.

Adult↗
PubMed1995

Relative position of porion and tragus in orthodontic patients.

In order to assess the relationship between the hard (porion-orbitale) and soft (tragus-orbitale) tissue Frankfurt planes, the relative positions of porion, orbitale, and tragus were evaluated on cephalometric radiographs. A 5-mm radiopaque disk was fixed on the right tragus of 160 white orthodontic patients (65 males aged 7 to 28 years, and 95 females aged 7 to 36 years), and a pre-treatment lateral cephalometric radiograph was taken. In every film the positions of orbitale, porion, and tragus were digitized, and the linear distances between the points, as well as the position of tragus relative to the skeletal structures, were calculated. The linear distances porion-orbitale and tragus-orbitale progressively increased with age, with a low variability in all age classes. The linear distances were always larger in the males than in the females. The tragus was always lower and more anterior than the porion, with vertical distances ranging from 1.2 to 19.8 mm. When the porion-tragus distance was expressed as a percentage of the porion-orbitale distance, the variability decreased. In the age classes, mean percentage horizontal projections from porion ranged from 18 to 23% of the porion-orbitale distance, mean percentage vertical projections ranged from 8 to 15%. Unfortunately, sample variability was large, and, in a single patient, the position of tragus relative to the skeletal structures could be predicted only with a large approximation.

Adolescent↗
PubMed1995

Facial morphometry of television actresses compared with normal women.

PURPOSE: The object of this investigation was to determine whether young women considered as beautiful differ in their three-dimensional facial characteristics from normal women of the same age and race. METHODS: The three-dimensional coordinates of 22 standardized soft-tissue facial landmarks were automatically collected in two groups of women using a noninvasive instrument. The first group consisted of 10 white television actresses selected only on the basis of their soft-tissue facial appearance ("beautiful" group); the second group included 40 healthy, white women selected according to criteria of dentofacial normality ("normal" group). The x, y, and z coordinates of the points collected on each woman were used to calculate several three-dimensional angles, linear distances, linear distance ratios, and facial volumes. RESULTS: The facial morphometric characteristics within the beautiful group were more uniform than within the normal group. On average, the beautiful women had a larger forehead, a larger middle facial third relative to the total face, a wider (left-right dimension) and less deep (anteroposterior dimension) face, a smaller nose, and a less convex face (in both the sagittal and transversal planes) than the normal women. CONCLUSION: The three-dimensional cutaneous facial characteristics of the beautiful women were significantly different from the characteristics of the normal women.

Adult↗
PubMed1995

A computerized non-invasive method for the assessment of human facial volume.

The three-dimensional coordinates of 22 standardized soft-tissue facial landmarks were used in the definition of a three-dimensional model of the adult human face. The model allows the estimation of the volume of the face in toto and of its parts (upper, middle and lower thirds, nose). Landmark coordinates were collected in 80 healthy young adults (40 men and 40 women selected according to criteria of dentofacial normality) by infrared photogrammetry by an automated instrument, and facial volumes calculated. Sample variability was larger in women than in men; the nose and the upper third of face had the largest variability regardless of gender. On average, all volumes computed in men were significantly larger than the corresponding values computed in women. Also the lower-to-middle third face ratio was significantly higher in men than in women. The sexual dimorphism in human facial volume did not involve the different parts of the face to the same extent: a large part of male facial volume preponderance was explained by the lower third of face. The proposed facial model could adequately represent the human face in all those research and clinical fields where noninvasive surface measurements could be employed alone or in support of conventional radiographic data.

Adult↗
PubMed1995

New television technique for natural head and body posture analysis.

A new television technique that proved to be faster than conventional photographic analysis has been developed and applied to the evaluation of the head and body natural standing posture in 303 healthy children, ages 6 to 11, and in 186 healthy young adults. In the lateral plane all subjects had extended head (soft tissue Frankfurt plane), with parallel Camper's and occlusal planes. The neck was halfway between the horizontal and vertical planes. Most angles significantly correlated with each other. The occlusal and neck angles showed a significant effect of age, being larger in children than in adults. In children the neck was more flexed, and the occlusal plane was more inclined downward. The results were in accord with previous photographic evaluations showing that the applied method was reliable and could be usefully employed in postural investigations. The results also confirmed that in healthy subjects, regardless of age, the soft tissue Frankfurt plane is extended, not horizontal.

Adolescent↗
PubMed1995

A three-dimensional evaluation of human facial asymmetry.

Soft-tissue facial asymmetry was studied in a group of 80 young healthy white Caucasian adults (40 men, 40 women) with no craniofacial, dental or mandibular disorders. For each subject, the 3-dimensional coordinates of 16 standardised soft-tissue facial landmarks (trichion, nasion, pronasale, subnasale, B point, pogonion, eye lateral canthi, nasal alae, labial commissures, tragi, gonia) were measured by infrared photogrammetry by an automated instrument. The form of the right and left hemifaces was assessed by calculating all the possible linear distances between pairs of landmarks within side. Side differences were tested by using euclidean distance matrix analysis. The mean faces of both groups were significantly asymmetric, i.e. the 2 sides of face showed significant differences in shape, but no differences in size.

Adult↗
PubMed1995

Fourier analysis of human soft tissue facial shape: sex differences in normal adults.

Sexual dimorphism in human facial form involves both size and shape variations of the soft tissue structures. These variations are conventionally appreciated using linear and angular measurements, as well as ratios, taken from photographs or radiographs. Unfortunately this metric approach provides adequate quantitative information about size only, eluding the problems of shape definition. Mathematical methods such as the Fourier series allow a correct quantitative analysis of shape and of its changes. A method for the reconstruction of outlines starting from selected landmarks and for their Fourier analysis has been developed, and applied to analyse sex differences in shape of the soft tissue facial contour in a group of healthy young adults. When standardised for size, no sex differences were found between both cosine and sine coefficients of the Fourier series expansion. This shape similarity was largely overwhelmed by the very evident size differences and it could be measured only using the proper mathematical methods.

Adult↗
PubMed1994

Maxillary versus mandibular arch form differences in human permanent dentition assessed by Euclidean-distance matrix analysis.

Euclidean-distance matrix analysis (EDMA) was used to analyse the dental arch form in 50 men and 45 women aged 20-27 yr with sound dentitions. Fourteen landmarks, corresponding to the centres of gravity (centroids) of the occlusal surfaces of all permanent teeth (right second molar to left second molar), were identified on the dental casts of subjects. All the possible linear distances between pairs of teeth were computed and maxillary/mandibular arch differences within sex were tested by EDMA. In both sexes, the maxillary arch was larger than the mandibular arch; arch shape was also significantly different. All teeth contributed to the shape difference between arches regardless of gender. EDMA also separated the influence of anterior and posterior teeth in the determination of upper/lower arch characteristics.

Adult↗
PubMed1994

Biomechanical model of the human mandible in unilateral clench: distribution of temporomandibular joint reaction forces between working and balancing sides.

In a previous article we reported on our development of a biomechanical analog of the human mandible and a simple support model was introduced. The model has been further developed to calculate the relative degree of load on the working and balancing sides of the temporomandibular joint during unilateral clench. The relative load on each joint is a function of the biting force, the geometric setting (subject's anatomy, points of application of the biting force on the dental arch and of the resultant of the forces of the masticatory muscles), and the value of the electromyographic asymmetry (relative contribution of working-versus balancing-side muscles) and activity indexes (relative contribution of masseter versus anterior temporal muscle of both sides). The proposed biomechanical model showed that the reaction forces that act on the temporomandibular joint during unilateral clench do not always load the balancing-side joint more than the working-side joint. Modifications of the asymmetry index changed the relative load between the two joints, and a higher temporal muscle activity increased the joint load on both the working and the balancing sides.

Biomechanical Phenomena↗