•Early parent guidance effectively reduces the prevalence and severity of DP and improves the cervical range of motion at three months. •Educating both parents and professionals about proper infant positioning on a national scale could help minimize public healthcare costs.

Recent advances in laser scanning technology provide the opportunity to examine faces in three dimensions. The aim of this prospective clinical study was to explore facial symmetry in healthy growing individuals and determine whether asymmetric changes occur during adolescent growth. Non-invasive laser surface scanning was performed to capture facial images of 60 Caucasian Finnish adolescents (30 males and 30 females, mean 11.5 years). Facial symmetry was analysed on images obtained at the initial scanning (T₁), 2.5 (T₂), and 4.5 (T₃) years thereafter. The final sample consisted of 39 adolescents (19 males and 20 females, mean 16 years). Three-dimensional images were processed and analysed using an in-house developed subroutine for commercial software. A mirror image was generated and superimposed on the original image to create a symmetric face and establish the midsagittal plane. The surface matching of the original face and the mirror face (amount of symmetry) was measured for the whole face, upper, middle, and lower thirds at tolerance level 0.5 mm and presented with colour maps. Three angular and 14 linear measurements were made based on 21 soft tissue landmarks, which have proven to be reliable. The results of the Friedman test showed that facial symmetry parameters did not significantly differ over time (P > 0.05). Mann-Whitney U-test did not reveal statistically significant differences between genders at any time point (P > 0.05). Facial growth of healthy individuals during adolescence is symmetric, although further investigation on larger randomized sample is suggested.

Deformational plagiocephaly is reported in up to 46.6 % of healthy infants, with the highest point prevalence at around 3 months of age. Few prospective studies on the natural course of skull deformation have been conducted, and we know of no studies using 3D imaging starting from the highest point prevalence period. In this prospective, population-based cohort study, we describe the course of cranial asymmetry and shape in an unselected population using 3D stereophotogrammetry and investigate factors associated with late cranial deformation and failure to recover from previous deformation. We evaluated 99 infants at 3, 6, and 12 months of age. We acquired 3D craniofacial images and performed structured clinical examinations and parental interviews at each visit. Eight outcome variables, representing different aspects of cranial shape, were calculated from a total of 288 3D images. Scores of asymmetry-related variables improved throughout the observation period. However, the rate of correction for cranial asymmetry decreased as the infants grew older, also in relation to the rate of head growth, and a significant amount of asymmetry was still present at 12 months. Positional preference at 3 months predicted an unfavorable course of cranial asymmetry after 3 months, increasing the risk for DP persisting. What is known: • The prevalence of deformational plagiocephaly spontaneously decreases after the first months of life. • Limited neck range of motion and infant positional preference increase the risk of deformational plagiocephaly during the first months of life. What is new: • Positional preference at 3 months predicts an unfavorable spontaneous course of deformation also from three to 12 months of age, presenting a potential target for screening and treatment. • The spontaneous rate of correction for cranial asymmetry decreases after 6 months of age, also in relation to the rate of head growth.

We recommend using OCLR as the primary measurement, although PCAI and wAS may also be useful in monitoring cranial asymmetry. The threshold of relative asymmetry required for a deformation to appear clinically significant is not affected by the child's age, and DD has no additional utility in monitoring DP compared to using only OCLR.