ABSTRACT
Individual and average growth patterns of the facial dimensions Nasion-Gnathion and Sella-Gonion, as related to statural growth were studied. The sample consisted of 134 girls aged 7-14 years. Data were analysed using a multivariate extension of the multilevel model for longitudinal data. The results confirmed that the mean growth curves of Nasion-Gnathion, Sella-Gonion and body height parallel each other to a large extent. At an individual level it appeared that the pubertal growth spurt of body height and the growth spurts of both facial dimensions are coincident. The major results of the present study pertain to the dynamic (age-dependent) relationship between statural growth and the growth of the face. It appears that there exists a stronger relationship between the growth velocities of standing height, Sella-Gonion and Nasion-Gnathion than between the actual lengths of the three variables themselves. The strongest relation was found between the growth velocity of body height and that of Sella-Gonion. These findings may be a contribution for diagnosis and treatment planning of individual cases.
Subject(s)
Body Height , Growth , Maxillofacial Development , Adolescent , Age Factors , Cephalometry , Child , Chin/anatomy & histology , Chin/growth & development , Female , Humans , Longitudinal Studies , Maxilla/anatomy & histology , Maxilla/growth & development , Multivariate Analysis , Nose/anatomy & histology , Nose/growth & development , Puberty , Sella Turcica/anatomy & histology , Sella Turcica/growth & developmentABSTRACT
Differences in craniofacial morphology in uni and bilateral cleft lip and palate were studied by roentgenocephalometry: 35 American children, treated with a lip adhesion procedure, and 26 Dutch children treated with a preoperative orthopedic procedure, both followed by a lip and/or palatal repair, were compared. A multivariate statistical approach was used to study the effects of the surgical procedures and of the age of the child when operated upon. The variables affected by the type of operation were: the relative length of the maxilla (PNS-ANS); the SNA angle; and the relative length of the mandible (Go-Po). The length of the maxilla was on average longer for those treated with preoperative orthopedics and the maxilla was largest for children whose hard palate had yet to be closed. This was also the case for the SNA angle except for children treated with the combined lip-soft palate closure procedure. The mandible followed pattern displayed by the maxillary length; it was larger for those treated with preoperative orthopedics. Significant effects of the timing of the surgery on the variables studied were also found. Postponement of the definitive lip closure resulted in a reduction of the maxillary length, whereas delay of soft palatal closure resulted in an increase of the maxillary length.
Subject(s)
Activator Appliances , Cleft Lip/surgery , Cleft Lip/therapy , Cleft Palate/surgery , Cleft Palate/therapy , Maxillofacial Development , Palatal Obturators , Adolescent , Age Factors , Cephalometry , Child , Child, Preschool , Cleft Lip/pathology , Cleft Palate/pathology , Clinical Protocols , Dental Occlusion , Evaluation Studies as Topic , Humans , Lip/surgery , Mandible/growth & development , Mandible/pathology , Maxilla/growth & development , Maxilla/pathology , Palate/surgery , Palate, Soft/surgery , Preoperative CareABSTRACT
Multilevel modelling of longitudinal data is an important new statistical technique. In this article some of the basic concepts and ideas of multilevel modelling are explained. The model is introduced by showing how individual and average growth can be modelled. The intercept, linear and quadratic coefficient, between and within variance, fixed and random part, and other concepts of multilevel modelling are explained. Attention is also given to the reading of statistical tables of the results of multilevel analysis. In the conclusion some of the advantages of multilevel modelling of cephalometric data are mentioned.
Subject(s)
Aging/physiology , Cephalometry , Maxillofacial Development/physiology , Models, Biological , Orthodontics , Cephalometry/methods , Child , Child, Preschool , Humans , Infant , Statistics as TopicABSTRACT
Multilevel analysis is used to describe the changes in vertical facial dimensions and their relationships in Dutch girls between 7 and 14 years of age. For the anterior face height (nasion-gnathion) and the posterior face height (sella-gonion) a fourth degree polynomial was fitted. The mandibular plane angle (sella nasion-gonion gnathion) could be described with a second degree polynomial. Low correlations were found between the growth parameters (intercept and age coefficient) of the anterior and posterior face height, which points to independent growth and development of the anterior and posterior face height. The individual length and growth velocity (at age 10.8) of the anterior face height and the mandibular plane angle showed substantial correlations. It was concluded that changes during growth with regard to the mandibular plane angle are more strongly related to the anterior than to the posterior face height.
