Showing papers by "Chiarella Sforza published in 1999"

The influence of crossbite on the coordinated electromyographic activity of human masticatory muscles during mastication.

Abstract: The analysis of the masticatory muscle activity in subjects with altered occlusal relationships could provide useful data of the functional impact of morphological discrepancies. Thirty subjects aged 16-18 years, with a sound, full permanent dentition, bilateral angle class I, and an overjet and overbite between 2 and 5 mm, were examined. The control group (10 male, 10 female) had no crossbite, while the crossbite group (four male, six female) had a posterior unilateral crossbite (five on the left side, five on the right side). The electromyographic activity of the left and right masseter and temporalis anterior muscles was recorded during 15 s of unilateral (left and right) chewing of gum, and expressed as a percentage of the maximum voluntary clench on cotton rolls. For each subject, the masticatory frequency, the confidence ellipse of the simultaneous differential left-right masseter and temporal activity (Lissajous figure), and an index of muscular symmetry, were computed to assess muscular coordination. In the crossbite subjects, the four analysed muscles appeared to contract with altered and asymmetric patterns. A large variability was found, and the confidence ellipses calculated for the chewing tests performed on the crossed sides were not significant, while the confidence ellipses of the uncrossed side chewing were different from the ellipses computed in the normal occlusion group. The altered occlusal relationship influenced the coordination of the masticatory muscles during chewing on both sides. The functional alteration was more apparent when the side with the altered morphology was directly involved, i.e. when chewing was performed on the crossbite side.

Three-dimensional facial morphometric assessment of soft tissue changes after orthognathic surgery.

Abstract: Objective. In this study, a 3-dimensional system with landmark representation of the soft tissue facial surface was applied for the evaluation of facial changes occurring after orthognathic surgery in 5 patients. Study Design. Standardized facial landmark acquisitions were performed before and 1 year after surgery (combined maxillary Le Fort I and sagittal mandibular osteotomies). The 3-dimensional coordinates of 22 facial soft tissue points were collected on each subject through use of a computerized noninvasive method and used to calculate a set of selected parameters. Results. Three-dimensional soft tissue analysis of patients was in general agreement with the type of surgery performed, with volumetric contraction of the lower facial third and expansion of the middle facial third. Moreover, negative effects of surgery were quantified (eg, an increase in alar base dimensions); the global asymmetry of facial soft tissues was increased by intervention, but asymmetry in the lower facial third was reduced. Conclusions. The method used in this study proved useful as a complementary diagnostic aid, enabling quantitative evaluation of the final soft tissue results of surgery, which were proportional to those expected on the basis of the type of treatment and skeletal data. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1999;88:549-56)

Soft-tissue facial morphometry from 6 years to adulthood: a three-dimensional growth study using a new modeling.

Abstract: A recently introduced three-dimensional computerized system with landmark representation of the soft-tissue facial surface allows noninvasive and fast quantitative study of facial growth. The aims of the present investigation were (1) to quantify growth changes in soft-tissue facial morphology, (2) to evaluate sex differences in growth patterns, and (3) to provide reference data for selected angular and linear measurements that could be of interest for the objective analysis of maxillofacial surgery or orthodontic patients. The three-dimensional coordinates of 22 standardized facial landmarks were automatically collected by automated infrared photogrammetry using the three-dimensional facial morphometry method in a mixed longitudinal and cross-sectional study, in which 2023 examinations were obtained in 1348 healthy nonpatient subjects between 6 years of age and young adulthood. Selected parameters (angles, linear distances, and ratios) were calculated and averaged for age and sex. Male values were compared with female values by means of Student's t test. Within each age group, linear distances were significantly larger in boys than in girls (p < 0.05) with some exceptions coinciding with the earlier female growth spurt, whereas angular measurements did not show a corresponding sexual dimorphism. Linear distances in girls had almost reached adult dimensions in the 12-to-13-year-old age group, whereas in boys a large increase was still to occur. This was most evident in the middle third of the face, where both sexes showed almost the same dimension and amount of growth up to the age of 13, with significant differences afterward, boys being larger than girls. On the contrary, in the lower third of the face, significant differences occurred throughout the whole investigated period, boys being always larger than girls. The male versus female angular comparison reflected the differential timing in attainment of adult proportions. The three-dimensional facial morphometry method allowed the noninvasive evaluation of a large sample of nonpatient subjects, leading to the definition of three-dimensional normative data about facial soft tissues. The method could supplement more invasive radiographic evaluations, allowing frequent examinations of children and adolescents before and during treatment, as well as in the follow-up.

Morphometry of the normal human ear: a cross-sectional study from adolescence to mid-adulthood.

Abstract: The objective of this study was to supply information about: (1) normal gender-based dimensions of ears (linear distances and ratios, area); (2) left right symmetry; and (3) growth changes between adolescence and mid-adulthood. The three-dimensional co-ordinates of several soft-tissue landmarks on the ears and face were obtained by an electromagnetic digitizer in 40 male and 33 female adolescents aged 12-15 years. 73 young female and 89 young male adults aged 19-30 years, and 41 male and 38 female adults aged 31-56 years. From the landmarks, paired car width and length were calculated and averaged for age and gender, as well as the relevant ratios, ear areas and angles relative to the facial midline, and indices of left right symmetry. Comparisons were performed by factorial analysis of variance. All ear dimensions were significantly larger in men than in women (P < 0.005). A significant effect of age was found (P < 0.005), with larger values in older individuals. On average, the three-dimensional position of ears was symmetric, with symmetry coefficients ranging between 94 and 96%. Data collected in the present investigation could serve as a database for the quantitative description of human ear morphology during normal adolescent and adult growth.

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

Abstract: 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.

The effects of a single intercuspal interference on electromyographic characteristics of human masticatory muscles during maximal voluntary teeth clenching.

Abstract: In 13 healthy subjects (eight men and five women, mean age, 22 years), an aluminum intercuspal interference (height, 0.25 mm) was placed on the maxillary right first premolar to study its effect on the contractile symmetry of the right and left masseter and anterior temporalis muscles when measured through a Percentage Overlapping Coefficient (POC), derived from surface electromyographic recordings of maximum voluntary teeth clenching. Additionally, and to estimate the potential of the experimental intercuspal interference to induce lateral displacement of the mandible, a Torque Coefficient (TC) was derived from surface electromyographic recordings. The conclusion was that the experimental occlusal interference gave rise to asymmetric contractile activity in the studied mandibular elevator muscles as well as a potential to displace the mandible in a lateral direction.

Dental arch size in healthy human permanent dentitions: ethnic differences as assessed by discriminant analysis.

Abstract: Race and ethnicity variably influence the form of the human craniofacial complex. In the present study, the effects of ethnicity and sex on the global size of normal adult dental arches were analyzed. The dental arches of 47 northern Chilean mestizos (25 men, 22 women) and 95 northern Italian Caucasians (50 men, 45 women) were cast in stone. All subjects had a complete dentition in both arches. In all models the coordinates of dental cusp tips were digitized using an image analyzer. The center of gravity of each tooth was computed and arches were interpolated using a polynomial model (y = ax + bx2 + cx3 + dx4). In all arches, the intercanine, intermolar, and mid-intercanine to mid-intermolar distances were computed from the dental centers of gravity. These arch distances were entered in a linear discriminant function analysis. The polynomial model accurately interpolated data points in all instances, and most of the dental arch form was determined by the first and second degree coefficients. On average, Italian Caucasian arches were smaller than Chilean mestizo arches. Male mean distances were larger than female distances regardless of ethnic group or arch. The linear discriminant analysis performed between male and female arches within ethnic groups was significant only for both Italian Caucasian arches, but the percentage errors for the classification of a new individual were very high (about 30%). Conversely, Italian Caucasian arches could always be discriminated from Chilean mestizo arches of the same sex with a much smaller error.

The use of linear and angular measurements of maxillo-mandibular anteroposterior discrepancies.

Abstract: Objectives To extend the assessment of the clinical significance of the measurement of the anteroposterior discrepancy between maxilla and mandible on the bisector of the palatal plane to mandibular plane angle to a large group of randomly selected patients of both sexes, and to verify the correlation of this measurement to well established angular and linear assessments of anteroposterior discrepancy. Design Retrospective analysis of pre-treatment lateral cephalometric radiographs. Setting and sample population The Laboratory of Functional Anatomy of the Stomatognathic Apparatus at Milan University, Italy. Three hundred and six orthodontic patients (165 males, 141 females) aged between 6 and 50 years. Experimental variable ANB angle; corrected ANB* angle which compensates for the position of the maxilla and rotation of the mandible relative to the cranial base; Wits appraisal; MM-Wits: linear distance between the projections of A and B points on the bisector of the palatal plane to mandibular plane angle. Results The MM-Wits distance was significantly correlated to two angles (ANB and ANB*), as well as to the Wits appraisal. All the correlations performed did not show sex- or age-characteristic patterns. The correlation to the corrected ANB* was the best among the three, with a correlation coefficient of 0.915, MM-Wits (mm) = 1.497 x ANB* (degrees) -6.784. From the correlation, reference values for the new measurement have also been estimated, and found to be between -0.65 and -6.85 mm for skeletal Class I individuals. Conclusion It is recommended that the diagnosis of orthodontic anomalies should be performed taking into consideration more than a single anteroposterior appraisal.

Mandibular shape and skeletal divergency.

Abstract: Pre-treatment lateral cephalograms of 41 skeletal Class I girls aged 11 to 15 were divided according to MP-SN angle: lower than 28 degrees (hypodivergent, 10 girls), between 31 and 34 degrees (normodivergent, 18 girls), or larger than 37 degrees (hyperdivergent, 13 girls). The mandibular outlines were traced and digitized, and differences in shape were quantified using the elliptic Fourier series. Size differences were measured from the areas enclosed by the mandibular outlines. Shape differences were assessed by calculating a morphological distance (MD) between the size-independent mean mathematical reconstructions of the mandibular outlines of the three divergency classes. Mandibular shape was different in the three classes: large variations were found in hyperdivergent girls versus normodivergent girls (MD = 4.61), while smaller differences were observed in hypodivergent girls (MD versus normodivergent 2.91). Mean size-independent mandibular shapes were superimposed on an axis passing through the centres of gravity of the condyle and of the chin. Normodivergent and hyperdivergent mandibles differed mostly at gonion, the coronoid process, sigmoid notch, alveolar process, posterior border of the ramus, and along the mandibular plane. A significant size effect was also found, with smaller mandibles in the hyperdivergent girls.

The mechanical advantage of the masseter muscle in subjects with different vertical and sagittal facial morphology.

Abstract: Objectives To study the relationships between the mechanical advantage of masseter muscle (the ratio between the muscular and the bite force moment arms) and two parameters describing vertical and sagittal facial morphology. Design Retrospective analysis of pre-treatment lateral cephalometric radiographs. Setting and sample population The Laboratory of Functional Anatomy of the Stomatognathic Apparatus at Milan University, Italy. Four hundred and sixty-eight orthodontic patients (209 males, 259 females) aged between 6 and 50 years. Measurements Mechanical advantage of masseter muscle, posterior-to-anterior facial height ratio, corrected ANB* angle were measured in all cephalograms. Results Masseter muscle mechanical advantage was, on average, 79.5% (SD 6.1), ranging between 53 and 94%. No sex-related characteristics were found. A moderate effect of age was found (r = 0.19), with a certain increment in the mean mechanical advantage in adults. No relationship with the corrected ANB* angle was found (r = 0.099), while a significant effect of the posterior-to-anterior facial height ratio was detected (r = 0.542). Conclusion The lack of correlation between the mechanical advantage of masseter muscle and corrected ANB* angle might be explained by: (1) when the occlusal point moves depending upon Angle skeletal classification, the ramus width might also modify, and both arms change; (2) the present assessment analysed only the lateral two-dimensional projection of a three-dimensional structure: the retroposition of occlusal point involves also a modification of line slope, and a subsequent reduction of its projection and arm.

Morphological variation analysis of the repeatability of soccer offensive schemes.

Abstract: A landmark-based statistical method, morphological variation analysis, for the quantification of the repeatability in the arrangement of body segments during the execution of sport actions has recently been developed. A two-dimensional shape is produced and its morphology is studied. The method was used to measure the within-team variability of the relative positions of players during the execution of offensive schemes in soccer. Two junior soccer teams of different technical abilities (semi-professional vs amateur), each playing two standardized offensive schemes of different difficulty (easier: throw-in; more difficult: wing attack) were filmed. Each scheme was repeated 25 (semi-professionals) or 10 (amateurs) times. For each repetition, the position of the players in a single significant frame was analysed using morphological variation analysis. The reproducibility of both schemes was higher among the semi-professionals than among the amateurs (two-way analysis of variance, P<0.005). The repeatability ...

Simplified cephalometric lines for the estimation of muscular lines of action.

Abstract: In the study of masticatory muscle performance, one of the biomechanical variables that can be estimated is the mechanical advantage of the masticatory muscles, namely, the ratio between the muscular moment arm and the bite force moment arm. In the present study, the position of the estimated line of action of the masseter muscle, drawn between gonion and orbitale (Go-Or) relative to dental (occlusal plane) and skeletal (Frankfort plane) references was analyzed in 431 pretreatment lateral cephalograms of orthodontic patients (195 males, 236 females) aged 6 to 50 years, and in the lateral tracings of the Bolton standards (6 to 18 years of age). The following measurements were evaluated: (1) skeletocutaneous class (soft tissue equivalent of Wits appraisal, linear distance in millimeters between the projections of points A' and B' on the occlusal plane); (2) angle between the Go-Or line and the perpendicular to the occlusal plane at the molar occlusal point; and (3) angle between the Go-Or line and the Frankfort plane. In the patients, the skeletocutaneous class ranged between--14.5 and 15.5 mm, without any sex- or age-related differences. The angle between the Go-Or line and the perpendicular to the occlusal plane was, on average, 39 degrees (range 15 to 53 degrees), and it decreased with advancing age; while the average angle between Go-Or and Frankfort plane was 42 degrees (range 30 to 54 degrees), and it increased in older patients. No effects of sex were found. The two angles were significantly correlated to each other, while no correlations were found with the sagittal jaw discrepancy. Similar results were obtained on the Bolton tracings. Overall, the present cephalometric analogue could be useful in biomechanical simulations.

Quantitative analysis of penile ultrasonographic shape during the erectile cycle: a new diagnostic tool for erectile dysfunction? Repeatability of the method and preliminary results

Abstract: Penile modifications during erection interest not only penile length and circumference, but also its size and shape. In this investigation, the size and shape repeatability of a single standardized ultrasonographic image of penis during flaccidity and erection was quantified in a group of 19 patients complaining of erectile dysfunction. The penis of each patient was placed in the dorsal position and scanned by a 10 MHz linear ultrasonographic probe at the site of maximal corporeal size: (1) during flaccidity; (2) after an intracorporeal injection of 10 micrograms alprostadil; and (3) after a genital stimulation. Each scan was repeated three times for each patient and printed. On each print the outline of the tunica albuginea was drawn, digitized, and mathematically reconstructed by Fourier series that allow a separate quantification of the size and shape differences. Reliability of the tunica albuginea outline and repeatability of probe positioning were separately assessed within patient and functional phase, and found to be good. The actual examinations of two impotence patients performed using the described method are also given. The shape of the corpora cavernosa may be potentially indicative of the homogeneous function of the tunica albuginea, and it may be of use in patients' follow up.