Biomedical subjects

G Serrao

Publications and source records attributed to G Serrao.

14 recordsLinked to original sources

PubMed1999

Size and shape of the human first permanent molar: a Fourier analysis of the occlusal and equatorial outlines.

Form can be viewed as a combination of size and shape. Shape refers to the boundary outline independently from its orientation, relation to reference planes, and dimension (or size). Shape and its changes could be quantified by mathematical methods such as the Fourier series. In this investigation, Fourier analysis has been used to quantify the morphologic characteristics (size and shape) of the outline of the occlusal surface and maximum circumference (equator) in 259 normal, healthy human first permanent maxillary and mandibular molars and to assess the effect of sex. Large within-group variability was found in the Fourier coefficients. Both equatorial and occlusal molar areas were on average larger in male than in female homologous teeth, but the difference was statistically significant only for the equatorial areas. The mean ratios between equatorial and occlusal dental areas were independent from arch (maxillary and mandibular), side, or sex. Both equatorial and occlusal outlines of left and right homologous molars within sex and arch were similar, without size and shape differences. Similarly, no sex differences in shape were found in the comparison of homologous teeth. The method used in the present study could supply information about dental shape in both its entirety and local variations. In particular, the method is extremely sensitive to local variations in dental shape, and it could be usefully employed to compare single teeth to a standard.

Adolescent↗

PubMed1998

A three-dimensional computerized mesh diagram analysis and its application in soft tissue facial morphometry.

A modified computerized mesh diagram analysis that allows rapid and independent quantifications of soft tissue facial size and shape in the three-dimensional space is presented. Normal references are provided, and the application of the method is also exemplified by the analysis of two maxillofacial surgical patients. The Three-Dimensional Facial Morphometry method has been used for the collection of the x, y, z coordinates of 22 soft tissue landmarks in 50 men and 50 women (all healthy young white adults). The method detects the three-dimensional coordinates of retroreflective, wireless markers positioned on selected facial landmarks with two charge-coupled device cameras, working in the infrared field. The midpoint between the right and left tragus landmarks served as the origin of the coordinate axes, and the landmark coordinates were rotated, setting the intercantheal line horizontal on both the frontal and the horizontal planes, and the Camper's plane inclined at -7.5 degrees on the sagittal plane. A standardized mesh of equidistant horizontal (dimension: half the upper face width), vertical (half the vertical projection of upper face height), and anteroposterior (half the horizontal projection of upper face depth) lines was consequently constructed. The lattice was replicated on the entire face and comprised 84 parallelepipeds. Both male and female reference meshes had a harmonious and symmetric appearance, with gender differences in facial size but not in facial shape. The standard normal reference was superimposed on the patient's tracing, and the global (size plus shape) difference was then evaluated by the calculation of the relevant displacement vectors for each soft tissue landmark. A global difference factor was calculated as the sum of the modules of all the displacement vectors. Consequently, a size normalization was performed, and the shape difference (size-standardized) was then evaluated by the calculation of new relevant displacement vectors for each landmark, as well as a shape--global difference vectors.

Adult↗

PubMed1998

Reliability of soft tissue references for anteroposterior measurement of dental bases.

The aims of the present investigation were to devise a new anteroposterior measurement of maxillomandibular discrepancies that would consider both hard and soft tissue contributions, and to verify the correlation of this measurement to a well-established linear assessment of anteroposterior discrepancy. On the pretreatment lateral cephalographs of 300 orthodontic patients (162 males, 138 females) aged between 6 and 50 years, the Wits appraisal and a new "soft tissue" Wits appraisal (linear distance between the projections of soft tissue A and B points on the bisecting occlusal plane) were measured. In the analyzed sample, the former was more variable than the latter. The two measurements were significantly correlated to each other without sex- or age-characteristic patterns. From the correlation, reference values for the new measurement were estimated and found to be between -1.9 mm and 5.4 mm for individuals with a normal occlusion. The new measurement could allow a more careful evaluation of the soft tissue drape together with the underlying hard tissue structure.

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↗

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

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↗

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

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↗

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↗

PubMedDate not supplied

Elliptic Fourier analysis of mandibular shape.

Craniofacial growth and development involve both size and shape variations. Shape variations can be assessed independently from size using mathematical methods such as the elliptic Fourier analysis, which allows a global evaluation of the shape of organs identified by their outlines independently from size, spatial orientation, and relation to reference planes. The mandibular outlines were digitized from the tracings of the Bolton standards (lateral view) from 1 to 18 years of age, and the age differences in shape independently from size were quantified using the elliptic Fourier series. A "morphologic distance" MD (i.e., a measurement of differences in shape) between each younger mandible and the oldest one was computed using the relevant Fourier coefficients like the cartesian coordinates in standard metric measurements. MD equals 0 when the profiles are identical. MD (Y) between the Bolton standard at 18 years of age and all the other Bolton tracings were significantly correlated (correlation coefficient r = 0.987, P < or = 0.001) with age (X) (semi-logarithmic interpolation Y = -3.87.log(e) X + 13.593). Differences between the size-independent shape of the Bolton standard at 18 years and the relevant plot at 1 year were located at the chin, gonion, coronoid process, anterior border of the ramus. Size differences were measured from the areas enclosed by the mandibular outlines. Mandibular area (Y) increased about 2.58 times from 1 to 18 years of age (X) (Y = -0.071.X2 + 4.917.X + 35.904, r = 0.997, P < or = 0.001). The shape effect was largely overwhelmed by the very evident size increments, and it could be measured only using the proper mathematical methods. The method developed could also be applied to the comparison between healthy and diseased individuals.

Adolescent↗