The complete guide to
not losing your head
while crafting dentures for the partially edentulous.
The first step is to get your hands on a patient, which
you can do so from the outdoor unit in Room No.2 where there’s usually a
different house officer every day. Tell them you want patients suitable for a
removable partial denture. Or alternatively, make friends with the guy called “Aamir”
who handles all the patients at the outdoor. Or, ask the Ma’am sitting in the
middle of the room for suitable patients (but she usually only has patients to
hand out on Tuesday, that is the impression day for the hospital side of the
department.)
A word about the quota. Each man for his own here. You
have to complete 12 credits in all, with tooth/prosthesis in any one quadrant
being equal to 0.5 credits, making a patient with a tooth missing in each
quadrant, a 2 credit one, which also boasts of being the theoretical maximum. (Some lucky people do get simple 2 credit
patients with all their central incisors missing, usually from trauma.)
It’s better to stick to at least one credit patients from
the start, because frankly, its too much effort for the half credit patients,
unless of course, you know a guy who knows a guy who knows how the magical
“pseudos” work in this department. :-)
1.
Initial Examination
2.
Allotment, paperwork
3.
Impression
4.
Study models, articulation
5.
Wax-up, clasps, tooth setup
6.
Trial (only for complicated cases like free end
saddles, or for anterior teeth)
7.
Flasking, de-waxing, curing
8.
Denture finishing, polishing
9.
Insertion
10.
Patient Instructions
11.
Quota book signatures
Initial Examination
Once you’ve gotten hold of a patient, just quickly go
through this initial exam, wherever you can, as soon as you can, to see if
they’re indeed suitable for an RPD.
- there must be no grossly carious teeth
- mobile abutment teeth, BDRs have to be extracted first
- most patients require scaling first, adherent tartar,
plaque, calculus deposits.
- fillings to be placed, crown-bridge work
- assure that the patient wants and requires a removable
prosthesis, and NOT a fixed one!
- enough edentulous space for a replacement
- be wary of free end saddles (too much effort things,
all over again)
- be wary of high risk patients, HCV, HBV, HIV etc.
- patients who come from distant areas and might not be
able to comply with multiple visits.
- children, less than 10-12 years old.
Allotment, paperwork
Now that you have a patient, you have to get yourself
assigned a supervisor, for which you need to call your patient over to the
college side of the department, get them approved by any demonstrator there (bring a mirror) and
get yourself assigned a supervisor. Then take the patient’s history (especially
their mobile number) and tell them to go and submit the money for the denture.
Once you have the fee receipt, fill in the details on your quota book and then
get it stamped from the room where they make the parchi, then take that stamped
book to Mr. Boota (crucial personality this, find out who he is) who’ll enter
your name in a register and give you a number. And now, you’re finally ready to
get started!
Supervisor. Mirror. Gloves. Boota. Amir. Stamp. Patient’s
complete history
Impression
Things you’ll need:
Alginate, gloves, napkins, bowl, spatula, impression trays,
impression compound, nurses, border moulding.
Explain to the patient what you’re going to do.
First, you have to select an impression tray by placing
it into the patient’s mouth and checking that it’s stable and doesn’t rock or
anything, there’s adequate space around all the teeth that its covering all the
tissues you want to reproduce.
Then have one of the nurses mix the alginate and load it
into an impression tray for you. You’ll only need the impression compound for
large span edentulous areas, free end saddles or a very high palate.
For Maxillary impressions:
Lower the chair.
Patient’s mouth at level with the operator’s elbow.
Operator stands behind on right side.
Patient seated upright
There’s a simple technique to this procedure that’s best
explained by doing .
Retract the patient’s left cheek with a mirror or your 'miracle' finger, and the right cheek with the impression tray that is now loaded, such
that the tray is initially at a right angle to the final position that it will
be in, and then twist it around as you move it in. Seat the posterior part first so
the excess flows towards the front and not towards the throat.
Next is what you call the border moulding. Which is basically
a combination of movements that ensures that the impression material has flowed
to all the important areas. Attend the demo for this, I can’t be bothered to
explain.
For Mandibular impressions:
Raise the chair
Patient’s mouth at level with the operator’s shoulder.
Operator stands in front on the right.
The technique here is similar to that for the maxillary
impression, except that you withdraw the left cheek with the side of the
loaded, inverted tray now and vice versa.
For tricky impressions, take some alginate on your gloved
finger and pack over deep areas in the arch, just before inserting the tray.
Setting time varies according to the consistency of the
mix, and its usually given on the pack that you’re using but an approximate
guess is 90-120 secs. Break the seal a
little first, then remove with a snap. Then go show it to your supervisor, and
if they say its okay then you may proceed to the next step.
Study models, articulation
Hard plaster, making a base, model trimmer, draw wax
pattern, block undercuts,
Articulation.
Once you have the impressions, its time to pour them
using hard plaster, which you can get from the tech. school building (second
floor) just behind the department. Once the plaster has hardened sufficiently,
you have to make a base of soft plaster. Just pile some up on the counter and
invert the tray containing the impression and the hard plaster model onto it.
Now once the base has hardened too, you have to remove
the tray and the alginate impression from the final model including the soft
plaster base using the wax knife. Be careful though, perfect impressions can be
useless if you fracture the model at this stage. Fill up any defects or bubbles
with more plaster. You can block the undercuts now too.
Trim the bases of the models with this machine here. Now
take the models and an indelible pencil to your supervisor who’ll draw a wax
pattern for the prosthesis on the model and tell you what clasps or retainers
you’re going to be adding, and finally mark the occlusion on both the models so
you can mount them on your articulator. Also, get your quota book signed now
for the impression that you’ve taken and for the teeth, wax and wire you’ll be
needing in the next steps too.
Wax-up, Clasps, tooth setup
You can get the wax, teeth and wire from the tech. school
again. Make the clasps first and secure them on the models with a bit of wax,
before you start with the wax-up, which is easy enough if you paid attention in
junior prostho in 2nd year(now you know why everything's important). Remember to block the undercuts
otherwise they can be a real nuisance during the insertion. Clasps shouldn’t be
adapted too closely to the tooth surface except on the buccal/labial side. The
tooth setup can be a bit tricky, but the key word here is aesthetics. Just match
the teeth you’re replacing with the natural dentition of the patient and keep
things symmetrical and neat. You’ll need a round bur for grinding the teeth
into size.
Trial insertion, occlusion
This is only for complicated cases like free end saddles,
or for anterior teeth. I only had to call back two or three of my patients for
this.
Flasking, de-waxing, curing
Once your supervisor has approved the wax-up, give it to
Rehmat for curing, which he works on after hospital hours and usually gives you
the denture by the next day.
Denture finishing, polishing
Trim the excess away using the big stone bur that’s mounted
on a motor. Use firm pressure for removing bulk in excess. Move the denture
over the bur when you’re going for the initial finish. Use a sand paper for a while to get a good finish. Now shift
to the hand held motor and the small stone bur which is to be used at low
speeds only. Clear the excess from the margins and from around the clasps and
the interdental areas with the round or the fissure bur. Now finish the denture
by polishing it first with the pumice bur and then the cake, and finally with
just this buff thing. Pop the denture in a bowl of water and call your patient
in the next day.
Insertion
If you’ve been meticulous in your work, this part
shouldn’t be much of a problem. However, clasps and undercuts have a way of
kinda growing overnight. Focus on seating the prosthesis properly in the
patient’s mouth first. Mostly the undercuts are to blame or the clasps need a
bit of adjusting. Once the prosthesis is seated, take an articulation paper
(from Aamir at the hospital side or Boota) and check for and remove high spots
using a round bur. Once everything’s in order, give the denture a final polish.
Check that the patient can speak, smile and chew properly. Show them a mirror
so they can admire their brand new teeth! Give the patient instructions on how
to care for their denture and basic oral hygiene.
Bring your supervisor around now so they can do a last
check and get the final signatures on the quota book too.
Good luck, and Godspeed!
- courtesy of Sajeel Ahmad