title: Prenatal ultrasound and postmortem histologic evaluation of tooth germs: an observational, transversal study.
abstract: BACKGROUND
  Hypodontia is the most frequent developmental anomaly of the orofacial complex, and its detection in prenatal ultrasound may indicate the presence of congenital malformations, genetic syndromes and chromosomal abnormalities. To date, only a few studies have evaluated the histological relationship of human tooth germs identified by two-dimensional (2D) ultrasonography. In order to analyze whether two-dimensional ultrasonography of tooth germs may be successfully used for identifying genetic syndromes, prenatal ultrasound images of fetal tooth germs obtained from a Portuguese population sample were compared with histological images obtained from fetal autopsies.
  
  
  METHODS
  Observational, descriptive, transversal study. The study protocol followed the ethical principles outlined by the Helsinki Declaration and was approved by the Ethics Committee of the School of Dental Medicine, University of Porto (FMDUP, Porto, Portugal) and of the Centro Hospitalar de Vila Nova de Gaia/Espinho (CHVNG/EPE, Porto, Portugal) as well as by the CGC Genetics Embryofetal Pathology Laboratory. Eighty-five fetuses examined by prenatal ultrasound screening from May 2011 to August 2012 had an indication for autopsy following spontaneous fetal death or medical termination of pregnancy. Of the 85 fetuses, 37 (43.5%) were randomly selected for tooth germ evaluation by routine histopathological analysis. Fetuses who were up to 30 weeks of gestation, and whose histological pieces were not representative of all maxillary tooth germs was excluded. Twenty four fetus between the 13(th) and 30(th) weeks of gestation fulfilled the parameters to autopsy.
  
  
  RESULTS
  Twenty four fetuses were submitted to histological evaluation and were determined the exact number, morphology, and mineralization of their tooth germs. All tooth germs were identifiable with ultrasonography as early as the 13(th) week of gestation. Of the fetuses autopsied, 41.7% had hypodontia (29.1% maxillary hypodontia and 20.9% mandibular hypodontia).
  
  
  CONCLUSIONS
  This results indicate that prenatal ultrasound is a reliable method for detecting of hypodontia an early gestational ages. Further studies with larger samples are needed to confirm these results.
authors.affiliation: Faculty of Dentistry, University of Porto (FMDUP), 4200-393, Porto, Portugal. marianaseabr@gmail.com.|Portuguese Catholic University (UCP), Viseu, Portugal. marianaseabr@gmail.com.
authors.forename: Mariana
authors.initials: M
authors.lastname: Seabra
authors.affiliation: Department of Oral Surgery of FMDUP, Porto, Portugal. afelino@fmd.up.pt.
authors.forename: António
authors.initials: A
authors.lastname: Felino
authors.affiliation: Pathology Laboratory of CGC Genetics/Centro de Genética Clínica, Porto, Portugal. rosete.nogueira@cgcgenetics.com.|Life and Health Sciences Research Institute (ICVS), School of Health Sciences (ECS), Campus of Gualtar, University of Minho, Braga, Portugal. rosete.nogueira@cgcgenetics.com.|ICVS/3B's - PT Government Associate Laboratory, Braga, Guimarães, Portugal. rosete.nogueira@cgcgenetics.com.
authors.forename: Rosete
authors.initials: R
authors.lastname: Nogueira
authors.affiliation: Prenatal Diagnosis Unit, Hospital of Vila Nova de Gaia/Espinho (CHVNG/E), Porto, Portugal. dr.francisco.valente@gmail.com.
authors.forename: Francisco
authors.initials: F
authors.lastname: Valente
authors.affiliation: Department of Production and Systems Engineering, and researcher in Algoritmi Centre University of Minho, Braga, Portugal. acb@dps.uminho.pt.
authors.forename: Ana Cristina
authors.initials: AC
authors.lastname: Braga
authors.affiliation: Department of Medical and Orofacial Genetics of FMDUP, Porto, Portugal. pvaz@fmd.up.pt.
authors.forename: Paula
authors.initials: P
authors.lastname: Vaz
mesh_terms: D000848:Anodontia / Q000000981:diagnostic imaging* / Q000453:epidemiology; D003933:Diagnosis; D005260:Female; D005333:Fetus / Q000473:pathology*; D005865:Gestational Age; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009805:Odontogenesis / Q000502:physiology; D011174:Portugal; D011247:Pregnancy; D012680:Sensitivity and Specificity; D014083:Tooth Germ / Q000000981:diagnostic imaging* / Q000196:embryology*; D018608:Ultrasonography, Doppler / Q000379:methods; D016216:Ultrasonography, Prenatal / Q000379:methods*