Microsoft Word - Yang Lee Proof 4-6.docx   Vol  3,  No  1  (2015)   ISSN  2167-­‐8677  (online)   DOI  10.5195/d3000.2015.32           http://dentistry3000.pitt.edu     New  articles  in  this  journal  are  licensed  under  a  Creative  Commons  Attribution  4.0  United  States  License.     This  journal  is  published  by  the  University  Library  System,  University  of  Pittsburgh  as  part  of  its  D-­‐Scribe  Digital  Publishing  Program  and  is  cosponored   by  the  University  of  Pittsburgh  Press.   Familial  aggregation  of  mandibular  prognathism   April  Lee1  and  Chris  Yang1     1  University  of  Pittsburgh  School  of  Dental  Medicine,  Pittsburgh  PA,  USA     Abstract     Mandibular  prognathism  is  a  hereditary  condi5on  where  there   is  an  excess  growth   of   the  mandible   in   rela/on  to  the  maxilla   that  can  be  associated  with  maxillary  retrusion,   mandibular  protrusion,  or  both.   Skeletal  mandibular  prognathism  is  most  prevalent  in  Eastern  Asian  popula7ons.  This  paper   focuses   on   a   Korean   family   with   skeletal   mandibular   prognathism   that   was   inherited   through   three   genera+ons.   Apparently,   neither   mandible   nor   maxilla   is   retruded   in   the   affected   individuals,  but  there   is  a  concave  facial  profile.  The  den77on  has  a  class   I  occlu-­‐ sion  with  skeletal  mandibular  prognathism,  and  the  only  way  to  treat  this  case  would  be  or-­‐ thognathic  surgery  with  the  help  of  orthodon4c  appliances.       Cita%on:   Lee   A   and   Yang   C.   (2015)   Familial   ag-­‐ grega%on  of  mandibular  prognathism.  Den$stry   3000.  1:a001  doi:10.5195/d3000.2015.32   Received:  March  20,  2015   Accepted:  March  26,  2015   Published:  April    8,  2015   Copyright:  ©2015   Lee  A   and   Yang  C.   This   is   an   open   access   ar!cle   licensed   under   a   Crea!ve   Commons   A!ribu%on   Work   4.0   United   States   License.   Email:  akl33@pi(.edu       Introduction   Mandibular  prognathism  is   a  complex,  hereditary  condition   where  the  skeletal  profile  is  con-­‐ cave:  the  mandible  is  large  or  there   is  underdeveloped  or  normal  maxil-­‐ la.  The  dentition  can  be  class  I  (not   necessarily  class  III)  in  order  to   have  true  skeletal  mandibular   prognathism.     The  condition  can  be  pre-­‐ sented  with  distinct  cephalometric   features  such  as  a  short  anterior   cranial  base  length,  acute  cranial   base  angle,  short  retrusive  maxilla,   proclined  maxillary  incisors,  retro-­‐ clined  mandibular  incisors,  an  ex-­‐ cessive  lower  anterior  face  height   and  obtuse  gonial  angle.  It  can  be   associated  with  maxillary  retrusion   or  mandibular  protrusion  or  both   [1].     Mandibular  prognathism   can  be  expressed  to  different  de-­‐ grees  based  on  sex  and  ethnicity.   Even  though  esthetics  is  an   initial  concern  for  a  patient   with  malocclusion,  there  can   also  be  functional  concerns   (i.e.,  temporomandibular  joint   dysfunction),  and  psychologi-­‐ cal  problems  that  may  affect   the  patient  [2,3].  In  this  pa-­‐ per,  a  family  segregating   mandibular  prognathism  is   described  with  the  suggestion   there  is  a  strong  genetic  com-­‐ ponent  to  this  phenotype.        Familial  aggrega%on  of  mandibular  prognathism   Vol  3,  No  1  (2015)        DOI  10.5195/d3000.2015.3 2    http://dentistry3000.pitt.edu   2   Case  Report   This  paper  describes  a  24-­‐ year-­‐old  female  who  has  been  con-­‐ cerned  about  her  esthetics  with   having  a  projected  mandible,  giving   her  a  concave  profile.  Her  maxilla  is   positioned  slightly  backwards  in   regards  to  the  mandible.  This  gives   her  an  appearance  of  “flat  nose”  and   seemingly  smaller  cheekbones.  She   has  slight  frontal  bossing,  and  con-­‐ sequently  her  forehead  is  not  in  line   with  the  maxilla  or  mandible,  giving   her  the  concave  profile.     The  patient’s  mother  has   mandibular  prognathism.  The   mother’s  side  of  the  family  mem-­‐ bers  has  similar  profiles:  three  of   her  mother’s  sisters,  one  of  her   mother’s  brothers,  and  her  grand-­‐ mother.  The  mother’s  sisters  all   have  children  who  do  not  have   mandibular  prognathism,  but  her   brother  has  one  daughter  with  sub-­‐ tle  sign  of  class  III  and  a  son  with   class  I.  However,  the  patient’s  father   and  her  younger  sister  both  have   straight  profiles  (Figure  1,  2,  3).     The  patient  was  still  con-­‐ cerned  with  her  looks,  so  she  was   considering  getting  orthodontics  or   orthognathic  surgery.  However,  her   dentition  was  class  I  occlusion  with   perfectly  normal  function.  There-­‐ fore,  nothing  was  performed.         Discussion   It  seems  that  mandibular   prognathism  is  most  prevalent  in   Eastern  Asian  population,  which   can  range  from  8-­‐40%.  There   seems  to  be  no  significant  sexual   preference  for  inheritability,  but   there  seems  to  be  significant  dif-­‐ ference  in  sexual  dimorphism.   There  can  be  five  distinct  sub-­‐ phenotypes  of  class  III  malocclu-­‐ sion:  1)  prognathic  mandible   with  long  face,  2)  maxillary  defi-­‐ ciency  with  decreased  vertical   dimensions,  3)  maxillary  defi-­‐ ciency  with  increased  vertical   dimensions,  4)  mild  prognathic   mandible  with  nor-­‐ mal  vertical  dimen-­‐ sions,  and  5)  combi-­‐ nation  of  prognathic   mandible  and  maxil-­‐ lary  deficiency  with   normal  vertical  di-­‐ mension  [1].    Of   those  subpheno-­‐ types,  this  family   seems  to  have  mild   prognathic  mandible   with  normal  vertical   dimensions.   According  to   the  literature,  man-­‐ dibular  prognathism  shows  auto-­‐ somal  dominance  with  incomplete   penetrance  with  variable  expressiv-­‐ ity,  or  it  could  be  multifactorial.  The   prevalence  varies  among  different   ethnicities,  and  it  can  show  variable   anatomic  characteristics  [1].  In  this   family,  no  one  on  her  father’s  side   was  affected  with  having  class  III   malocclusion,  but  many  individuals   on  her  mother’s  side  of  the  family   were  affected.  There  seems  to  be  no   sexual  preference  in  inheritability.     As  a  dentist,  if  the  patient  is   concerned  with  esthetics,  the  den-­‐ tist  can  help  the  patient  to  feel  more   confident  by  considering  orthodon-­‐ tics  or  orthognathic  surgery,  but                      Familial  aggrega%on  of  mandibular  prognathism   Vol  3,  No  1  (2015)        DOI  10.5195/d3000.2015.3 2    http://dentistry3000.pitt.edu   3   s/he  should  also  be  able  to  present   the  negative  aspects  of  the  treat-­‐ ment.    If  the  patient  was  not  con-­‐ cerned  with  esthetics  but  the  func-­‐ tion  was  an  issue,  then  the  dentist   should  foresee  the  problem  for  the   patient  in  the  long  term  and  give  all   the  options  available  for  the  patient   to  progress  with  treatment.     Since  the  patient  had  no   functional  problems  with  occlusion,   the  dentist  should  discuss  with  pa-­‐ tient  the  pros  and  cons  of  orthodon-­‐ tics  or  orthognathic  surgery.  The   pros  would  be  improving  esthetics,   but  on  the  downside,  it  can  de-­‐ crease  function,  weaken  teeth,  long   recovery  period,  and  create  a  finan-­‐ cial  burden  for  the  patient.       References     1.    James  K.  Hartsfield  Jr.,  Lorri  Ann   Morford  and  Liliana  M.  Otero  (2012).   Genetic  Factors  Affecting  Facial   Growth,  Orthodontics  -­‐  Basic  Aspects   and  Clinical  Considerations,  Prof.  Fa-­‐ rid  Bourzgui  (Ed.),  ISBN:  978-­‐953-­‐51-­‐ 0143-­‐7,  InTech,  Available  from:   http://www.intechopen.com/books/ orthodontics-­‐basic-­‐aspects-­‐and-­‐ clinicalconsiderations/   genetic-­‐factors-­‐affecting-­‐facial-­‐ growth     2.  Orthodontic-­‐surgical  treatment  of   Class  III  malocclusion  with  extraction   of  an  impacted  canine  and  multi-­‐ segmented  maxillary  surgery.   Janson  M,  Janson  G,  Santana  E,  de   Castro  RC,  de  Freitas  MR.   Am  J  Orthod  Dentofacial  Orthop.   2010  Jun;137(6):840-­‐9.  doi:   10.1016/j.ajodo.2007.12.036.   PMID:  20685541       3.  Surgical-­‐orthodontic  treatment  of  a   skeletal  class  III  malocclusion.  Katiyar   R,  Singh  G,  Mehrotra  D,  Singh  A.  Natl   J  Maxillofac  Surg.  2010  Jul-­‐Dec;   1(2):143-­‐149.  PMCID:  PMC3304204