support.  This  is  best  given  by  a  backward  extension  of  the  model,  so
as  to  permit  motion  of  the  two  halves  of  the  articulator,  somewhat
resembling  that  of  the  natural  jaws ;  though  many  partial  cases  do
not  require  such  an  extension.  In  putting  this  wax  rim  on  the  plate,
it  is  better  in  all  cases  to  trim  it,  as  is  done  for  full  upper  sets ;  but
where  there  are  remaining  teeth,  the  antagonism  of  these  determines
the  proper  closure  of  the  mouth,  and  this  is  not  essential.  The  plate
and  adherent  wax  are  placed  in  the  mouth;  the  patient  is  then  re-
quested, to  close  the  mouth  naturally,  imbedding  the  teeth  of  tlie  lower
jaw  in  the  wax.  While  the  mouth  is  thus  closed,  the  wax  on  the  out-
side of  the  teeth  and  alveolar  ridge  is  pressed  closely  against  them.
This  done,  the  plate  and  wax  impression  are  carefully  removed,
filled  with  plaster,  and  placed  on  a  piece  of  wet  paper,  with  the  wax
downward.  The  upper  side  of  the  plate  is  then  oiled.  As  the  plaster
stiffens,  it  may  be  applied  until  it  is  raised  half  an  inch  above  the  plate,
and  extended  back  of  it  on  the  paper  an  inch  and  a  half  or  two  inches.
As  soon  as  the  plaster  has  set,  its  edges  may  be  neatly  trimmed ;  and  at
the  back  of  the  surface  next  the  paper  a  deep  transverse  or  T-shaped
groove  should  be  cut,  to  serve  as  a  mould  for  the  formation  of  a  cor-
responding ridge  on  the  half  model  with  which  this  is  to  antagonize.
