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Background The aetiology of the canine displacement still remains controversial. Some authors implicated a deficiency in maxillary width as a local mechanical cause for impacted canines. The aim of the study was to examine whether there is a relationship between impacted maxillary canines, early diagnosed by using panoramic radiographs, and the morphology of the maxilla on 3D model casts. Methods The displaced maxillary canines (DMC) group consisted of 24 patients (mean age, 9.1 ± 1.1 years), while the control group consisted of 25 subjects (mean age, 8.7 ± 0.9 years). Seven measurements were calculated on the digital casts of each subject: intermolar width (IMW), arch length (AL), depth of the palatal vault (PVD), available arch space (AAS), the sum of the anterior segments (SAS), the right/affected (R-Af) and left/unaffected (L-Un) available spaces. Results Both IMW and AL in the DMC group were significantly decreased relative to the control group (P

The lips and their relationship with the positions of anterior teeth considerably affect a person's smile and facial esthetics in general. In this study, the changes in lip dimensions and position in three-dimensions during the period between adolescence (12 boys and 12 girls aged 13–15 years) and young adulthood (10 men and 11 women aged 20–24 years) in normal, untreated subjects were measured, along with the age-related modifications in the clinical crown dimensions of maxillary and mandibular anterior teeth. The three-dimensional coordinates of selected soft-tissue facial and dental landmarks were directly digitized on the subjects using a non-invasive electromagnetic instrument. From the landmark coordinates, the total vermilion and upper lip heights; mouth width; intercanine and interincisor distances; clinical crown heights and widths of anterior teeth; interlabial, nasolabial, mentolabial, dentolabial and inciso-occlusal angles were calculated. Mean values for each sex and age group were computed and compared using two-way factorial analysis of variance. Results have shown that soft-tissue growth in the lip area has not subdued in adolescent males, while it has slowed in females; moreover, there was some degree of eruption of the maxillary anterior teeth in adolescent males, thus modifying dento-labial relationships. On average, males have a tendency toward a wider, thinner, and flatter lip area with growth. The various growth phenomena still to take place in adolescent males should be taken into consideration when commencing treatment: enucleation of four premolars may for example enhance a natural tendency toward a flatter lip area.

Background The objectives of this study were to develop and validate a novel analysis protocol to measure linear and angular measurements of tip and torque of each tooth in the dental arches of virtual study models. Methods Maxillary and mandibular dental casts of 25 subjects with a full permanent dentition were scanned using a three-dimensional model scanner. Sixty points per arch were digitized on each model, five points on each tooth. A custom analysis to measure linear distances and angles of tip and torque was developed using a new reference plane passing as a best-fit among all of the lingual gingival points, with the intermolar lingual distance set as the reference X-axis. The linear distances measured included buccal, lingual, and centroid transverse widths at the level of canines, premolars, and molars as well as arch depth and arch perimeter. Results There was no systematic error associated with the methodology used. Intraclass correlation coefficient values were higher than 0.70 on every measure. The average random error in the maxilla was 1.5° ± 0.4° for torque, 1.8° ± 0.5° for tip, and 0.4 ± 0.2 mm for linear measurements. The average random error in the mandible was 1.2° ± 0.3° for torque, 2.0° ± 0.8° for tip, and 0.1 ± 0.1 mm for the linear measurements. Conclusions A custom digital analysis protocol to measure traditional linear measurements as well as tip and torque angulation on virtual dental casts was presented. This validation study demonstrated that the digital analysis used in this study has adequate reproducibility, providing additional information and more accurate intra-arch measurements for clinical diagnosis and dentofacial research.

To identify reference standards and possible esthetic features in facial proportion and form of Italian adult women.A three-dimensional electromagnetic digitizer was used to collect the coordinates of 50 facial landmarks (forehead, eyes, nose, cheeks, mouth, jaw, ears) in 71 healthy, reference women (18-30 years old) and in 48 "attractive" women selected during a beauty competition; soft tissue facial angles, distances and volumes were computed.Attractive women had wider faces with a relatively larger upper facial third (forehead); a larger facial width relative to facial height. The mouth was larger, and lips were more prominent; the interlabial angle was reduced. Overall, the soft-tissue profile was more prominent, with a larger maxillary prominence relative to the mandible. Faces in the attractive women were more flat in the horizontal plane. For several of the analyzed measurements, similar patterns were observed for the 36 women participants to the semi-final stage of the beauty competition, the 12 finalists, and the winner. The winner of the beauty competition deviated from the reference women more than the other two groups of attractive women.Esthetic reference values were determined for a population of 18-30 year olds that reflect contemporary society.

To identify reference standards and possible esthetic features of facial size and form of Italian adolescent boys and girls.A three-dimensional electromagnetic digitizer was used to collect the coordinates of 50 facial landmarks (forehead, eyes, nose, cheeks, mouth, jaw, ears) in 231 healthy, reference adolescents (10-17 years old) and in 93 "attractive" adolescents selected by a commercial casting; soft tissue facial angles, distances and volumes were computed.Attractive adolescents had wider and shorter faces than reference subjects of the same age and sex, with relatively larger upper and middle facial thirds, and a reduced mandible relative to the maxilla. Lips were larger and more prominent, and the nasolabial angle was reduced, but in older boys the effect was reversed. The prominence of the soft-tissue profile, and of the maxilla relative to the mandible, were larger in attractive boys, but smaller in attractive girls than in their reference peers. Attractive adolescents had a relatively less prominent chin relative to the lower lip, with increased values of the mentolabial angle. In the horizontal plane, attractive "young" adolescents had a more obtuse mandibular convexity angle, while the opposite pattern was observed in the "old" adolescent subjects, with a relatively more prominent chin. Attractive adolescents had smaller noses than reference subjects of the same age and sex.Esthetic reference values have been identified which could be used to determine optimal timing and goals in orthodontic treatment.

The aim of the current investigation was to quantitatively analyze the relation between the activity of masticatory muscles and the inclination of the mandibular plane in a group of 73 healthy white men aged 20-36 years. The three-dimensional coordinates of soft-tissue landmarks gnathion and left and right gonion were digitized using an electromagnetic computerized instrument, the orientation of mandibular plane relative to the true vertical was computed and projected on the anatomical sagittal plane. The electromyographic (EMG) potentials of left and right masseter and temporalis anterior during maximum voluntary teeth clenching were recorded, and the mean EMG amplitude calculated. Two groups of men with opposite facial morphology were then selected: all men with a steep mandibular plane (higher than the mean plus one standard deviation) entered a first group (10 'long face' subjects), while all men with a relatively more horizontal mandibular plane (lower than the mean minus one standard deviation) entered a second group (13 'short face' subjects). Mean EMG potentials computed in the two groups were compared by using Student's t -test for independent samples. All the EMG potentials recorded during maximum voluntary clench in the 'long face' men were lower than that recorded in the 'short face' men, with statistically significant differences for all four analyzed muscles (p < 0.05). In conclusion, a non-invasive three-dimensional method confirmed that facial morphology and muscular function are significantly related, at least in men with a sound stomatognathic apparatus.

Background The purpose of this controlled study was to investigate indirect effects on mandibular arch dimensions, 1 year after rapid palatal expansion (RPE) therapy. Methods Thirty-three patients in mixed dentition (mean age 8.8 years) showing unilateral posterior crossbite and maxillary deficiency were treated with a RPE (Haas type) cemented on the first permanent molars. Treatment protocol consisted of two turns per day until slight overcorrection of the molar transverse relationship occurred. The Haas expander was kept on the teeth as a passive retainer for an average of 6 months. Study models were taken prior (T1) and 15 months on average (T2) after expansion. A control group of 15 untreated subjects with maxillary deficiency (mean age 8.3 years) was also recorded with a 12-month interval. Stone casts were digitized with a 3D scanner (3Shape, DK). Results In the treated group, both mandibular intermolar distance (+1.9 mm) and mandibular molar angulation (+9°) increased. Mandibular incisor angulation showed an increase of 1.9°. There was little effect on intercanine distance and canine angulation. Controls showed a reduction in transverse arch dimension and a decrease in molar and canine angulation values. Conclusions RPE protocol has indirect widening effects on the mandibular incisors and first molars.