ABSTRACT
AIM: This was to determine the relative contribution of genetic factors on the morphology of occlusal surfaces of mandibular primary first molars by employing the twin study model. METHODS: The occlusal morphology of mandibular primary first molar teeth from dental casts of 9 monozygotic (MZ) twin pairs and 12 dizygotic (DZ) twin pairs 4 to 7 years old, were digitized by contact-type three-dimensional (3D) scanner. To compare the similarity of occlusal morphology between twin sets, each twin pair of occlusal surfaces was superimposed to establish the best fit by using computerized least squared techniques. Heritability was computed using a variance component model, adjusted for age and gender. RESULTS: DZ pairs demonstrated a greater degree of occlusal morphology variance. The total amount of difference in surface overlap was 0.0508 mm (0.0018 (inches) for the MZ (n=18) sample and 0.095 mm (0.0034 inches) for the DZ (n=24) sample and were not statistically significant (p=0.2203). The transformed mean differences were not statistically significantly different (p=0.2203). Heritability estimates of occlusal surface areas for right and left mandibular primary first molars were 97.5% and 98.2% (p<0.0001), respectively. CONCLUSIONS: Occlusal morphology of DZ twin pairs was more variable than that of MZ twin pairs. Heritability estimates revealed that genetic factors strongly influence occlusal morphology of mandibular primary first molars.
Subject(s)
Molar/anatomy & histology , Tooth Crown/anatomy & histology , Tooth, Deciduous/anatomy & histology , Twins, Dizygotic/genetics , Twins, Monozygotic/genetics , Child , Child, Preschool , Female , Genetic Variation/genetics , Humans , Image Processing, Computer-Assisted/methods , Imaging, Three-Dimensional/methods , Male , Mandible , Models, DentalSubject(s)
AIDS-Related Opportunistic Infections , HIV Infections , Mouth Diseases , AIDS-Related Opportunistic Infections/classification , AIDS-Related Opportunistic Infections/epidemiology , AIDS-Related Opportunistic Infections/pathology , Acquired Immunodeficiency Syndrome/classification , Acquired Immunodeficiency Syndrome/epidemiology , Acquired Immunodeficiency Syndrome/pathology , Child , Child, Preschool , HIV Infections/classification , HIV Infections/epidemiology , HIV Infections/pathology , Humans , Infant , Mouth Diseases/classification , Mouth Diseases/epidemiology , Mouth Diseases/pathology , PrognosisABSTRACT
Pierre Robin sequence (PRS) is a congenital abnormality characterized by micrognathia and glossoptosis, with or without cleft palate. Patients with PRS may demonstrate various pediatric conditions such as associated syndromes, respiratory distress, feeding difficulties, or middle ear pathology. The purpose of this study was to determine, by means of a retrospective computerized review of patient records, the presence of these pediatric conditions in a sample of 55 confirmed patients with PRS. Five patients (9.1%) exhibited associated syndromes; 20 (36.4%) had respiratory distress requiring no assistance; and 10 (18.2%) exhibited severe respiratory distress requiring tracheotomy. A total of 30 patients (54.5%) had early feeding difficulties requiring mechanical assistance to maintain adequate nutrition, and 50 (90.9%) had multiple episodes of otitis media. Chi-square analysis revealed a statistically significant relationship between the presence of respiratory difficulties and the need for feeding assistance (P = 0.012); and a highly significant relationship between the presence of otitis media and subsequent myringotomy tube placement (P < 0.001). Pediatric dentists who treat children with PRS should be aware of these relationships when obtaining medical history before establishing strategies to implement a treatment plan.
