Two-dimensional vs three-dimensional assessment of soft tissue facial profile: a non invasive study in 6-year-old healthy children.

AIM: In medical practice, the analysis of facial soft tissues often complement (or even supplement) the evaluation of the hard-tissue relationships. Current technology provides reference data in three dimensions, but clinical practice still uses two-dimensional photographs. In the current study, two-dimensional photographic and computerized, three-dimensional angles measured on the facial profile of children were compared. METHODS: Two-dimensional angular measurements (facial convexity including/excluding the nose; maxillary prominence; nasal prominence; nasolabial; mentolabial; maxillo-labio-mandibular; interlabial) were obtained on the facial profile photographs of 55 boys and 31 girls aged 6; measurements were compared to three-dimensional computerized data collected on 27 boys and 28 girls of the same age and ethnic group. RESULTS: On average, in boys, only the angles of facial convexity including the nose, interlabial, nasolabial and maxillo-labio-mandibular showed differences between the means larger than 2 degrees (up to 2.5 degrees). Statistically significant differences (P<0.05, Watson-Williams' test) were found for the angle of facial convexity including the nose and the maxillary prominence angle. In girls, differences between the two methods larger than 2 degrees were found for the interlabial, maxillo-labio-mandibular (statistically significant), and mentolabial angles (differences up to 7 degrees, corresponding to 4% of the relevant mean). CONCLUSION: The two-dimensional photographic and the three-dimensional computerized data compared in the current study, even not superimposable, seemed sufficiently interchangeable, at least from a clinical point of view. A particular attention should be given to the recording of lip position.

Three-dimensional hard tissue palatal size and shape in human adolescents and adults.

Hard tissue palatal dimensions and shape in 29 boys and 32 girls (mean age 14 years) and 30 men and 35 women (mean age 20 years), all with a complete permanent dentition including the second molars, and free from respiratory problems, were analyzed. Palatal landmarks were digitized with a computerized 3D instrument, and their coordinates were used to derive a mathematical model of palatal form. Palatal shape (size-independent) was assessed by a four-order polynomial in the sagittal and frontal plane projections. Palatal dimensions in the frontal and sagittal planes were computed, and compared between ages and sexes by two-way factorial analyses of variance. The effect of age on palatal shape was different in the two sexes: while in females the curves in both the frontal and sagittal planes were practically superimposed, in males the youngest subjects had somewhat 'lower' curves than the oldest subjects. Sex had a significant (p<0.05) effect for all variables. Age was significant only for palatal slope in the sagittal plane (p<0.01), and for raphe inclination in the horizontal plane (p<0.05). For all variables but palatal length in the sagittal plane, a significant (p<0.01) sexxage interaction was found: while in males all linear variables were larger in adults than in adolescents, the reverse was found in females. Overall, while in adolescent females palatal form appeared to have already attained adult characteristics, in males some modifications between adolescence and young adulthood were measured. These modifications should be taken into consideration as a possible factor of relapse after orthodontic treatment.