Introduction to Clinical
• Clinic 1. History taking, examination,
treatment planning, and Primary
– Lab1. SM & custom trays.
• Clinic 2. Secondary/master/final
– Lab 2. Secondary/master/final casts
& occlusal wax rims (record blocks)
• Clinic 3. Registration stage:
1. Aesthetics (maxillary wax rim)
2. Vertical (VD) & horizontal (RCP)
3. Shade & Mould.
– Lab3. : Mounting teeth arrangement
• Clinic 4. Try in
– Repetition of previous visit.
– Post dam determination.
– Lab 4.: denture processing: flasking,
dewaxing, packing, curing,
deflasking, finishing and polishing.
• Clinic 5. Insertion
• Clinic 6. Review
Primary Impression-summary of the
Residual ridges, tuberosities and hamular notches,
functional width and depth of the labial and buccal
sulci, including frena.
Hard palate and its junction with the soft palate.
Residual ridges and retromolar pads.
Functional labial and buccal sulci (including frenal
and external oblique ridges)
Lingual sulci, lingual frenum, mylohyoid ridges and
Mucosa: stratified squamus epithelium & connective
tissue (lamina propria)
Submucosa: connective tissues made of dens to loose
If firmly attached: withstand pressure
If loose, thin, traumatized, mobile, flappy: it wont be suitable
to withstand pressure-not resilient.
Masticatory mucosa (keratinized): hard palate,
Mid palatine suture: Submucosa is extremely thin-
Horizontal portion of the Hard palate: 1 support for
Rugae areas: set at an angle with the residual ridge-
2 support areas.
The Palatal Gingival Vestige (remnants of
the lingual gingival margin)
It is the remains of the palatal gingiva. After
tooth extraction the position of the vestige
remains relatively constant, the same as the
incisive papilla. This can be a very helpful
pointer for posterior tooth positioning during
Submucosa: devoid of glandular tissues. Dense
collagenous fibers. Relatively thin, but sufficient to
provide support for the denture base.
Crest of the ridge:
Prone to resorption.
2 support area.
Inclined facial surfaces
Loses it’s firm attachment
Offers little support
Cannot withstand pressure
Two orifices one each side of the midline.
Coalescence of several mucous glands - always
located in the soft palate. They act as collecting
ducts for a group of minor palatine salivary
Usually 2mm in front of the fovea palatine
Not the junction of the hard and soft palate-
always on the soft palate.
Glandular tissues-because it is not supported by
bone, it could be compressed and relocated with the
impression to complete the palatal seal.
Crest of the residual ridge
Ridge is similar to that of the upper in healthy
Attachment varies considerably. In some
people, the submucosa is loosely attached to
When securely attached to the bone, the
mucous membrane is capable of providing
support for the denture. However, because
underlying bone is cancelous, the crest of the
residual ridge may be not favorable as a
primary stress bearing area for the lower
Buccal shelf area
The mucous membrane is more loosely attached and
less keratinized than that covering the residual ridge.
Although the mucous membrane may not be as
suitable histological to provide support for the
denture, the bone of the buccal shelf area is covered
by a layer of cortical bone. This plus the fact that the
shelf lies at right angle to the vertical occlusal forces,
makes it the most suitable primary stress bearing
The external oblique ridge does not govern the extension of the
buccal flange because the resistance or lack of it varies widely. The
buccal flange may extend to the external oblique ridge, up onto it or
even over it depending on the location of the muco buccal fold.
The bearing of the denture on muscle fiber of the buccinator would
not be possible except for the fact that the fibers run parallel to the
base, and ,hence , its action is parallel to the border and not at right
The disto buccal border must converge rapidly to avoid the action of the
masseter which is pushing inward the buccinator.
Distal extension is limited by
Pterygo mandibular raph.
The sharpness of the boundaries of the retromolar
fossa. (the denture should extend slightly to the
lingual into the pearl shaped retro molar pad.
The retro molar pad is a triangular soft pad of
tissue. Its mucosa is composed of thin non
keratinized epithelium. It submucosa contains
Fibers of the buccinator and superior constrictor
Pterygo mandibular raph
Fibers of the temporalis
Because of theses structures, the denture base
should only extend to one half to two third the
retro molar pad.
The retro molar pad:
It is split into two sections. The anterior section is usually firm and
fibrous. It is important for denture support and preventing distal
The mylohyoid ridge:
Following the extraction of natural teeth and subsequent resorption,
the mylohyoid ridge becomes more prominent. This can result in
mucosal soreness beneath the denture bearing area over the
It is a thin sheet of fibers and in a relaxed
state will not resist the impression material.
Carrying the border under the mylohyoid
cannot be tolerated. The contraction of this
muscle will displace the denture.
Fortunately, the denture in the posterior area
of the mylohyoid is beyond its attachment
because the mucobuccal fold is not in this
In the retro mylohyoid fossa the border of the
denture move back toward the body of the
mandible producing the S curve of the lingual
In the anterior region, a depression, the pre
Making the Primary Impression
Selection of the impression tray
impression trays are rigid containers used to
carry the impression material into the mouth.
They also support it while it sets or harden,
and subsequently during removal from the
mouth and when casts are poured.
Wide selection is available in metal or plastic.
Selection is based on:
The need to accommodate an appropriate amount
of the impression material.
The design or extent of the tray to the anatomical
landmarks outlined previously.
Provided in a wider range of sizes.
Needed to be cleaned and sterilized before reuse.
Plastic trays are intended to be disposable
Check that the tray is not over extended or under
extended. Then load the impression material and make
the mandibular impression standing in front of the
patient. For the maxillary impression, the clinician should
be positioned behind the patient. As this affords more
control over the upper tray and also allow the patient’s
head to be leaned forward should they experienced
nausea during the impression procedure.
Inadequate final impression: contact clinician to discuss
possible risks of proceeding with the case
Model fractures upon removal from impression.
Large positive or negative defects, or flaws in critical areas.
Poor surface quality of the model due to water/saliva/blood
contamination or improper mixing of gypsum, showing a
powdery, friable surface.
Loss of or damage to critical areas during model trimming
(examples: retromolar pad, hamular notch and muscle
Producing Casts & Special Trays
• Ensure that impressions have been decontaminated prior to dispatch
to the lab.
• Preparing the primary cast:
– Principally used to provide bases on which
customized special trays are constructed.
– Also useful for planning treatment, for example for
outlining the potential supporting areas of the
– Cast are made in Plaster of Paris ( β hemihydrate
of calcium sulphate) & Stone (α- hemihydrate of
– Pour using 50:50 mixture of plaster of Paris/ dental
stone (vacuum mixed) under vibration.
– Make the base at least 10mm thick to be
sufficiently robust to survive subsequent handling.
• Powder/liquid ratio
– Thin mix: longer setting time, poor surface
hardening, setting expansion is low, easier to pour.
– Thick mix: the opposite.
• Spatulation time: time taken to mix the powder &
liquid into creamy consistency.(30-60 sec.)
Increasing the spatulation time:
– Rapid set.
– Decreases surface hardness.
– Increases the setting expansion.
• Temperature: water temp. up to 40 cº decreases
setting, above 40 cº increases setting.
• Chemical additives. E.g. Borax increases setting time.
• Read the prescription before beginning all procedures.
• Box master model impressions- Diagnostic casts do not require
• Measure dental stone and water according to manufacturer's
• Add powder to water rather than water to powder. For best
results, vacuum mixing is recommended.
• Do not invert impressions to develop a base until the stone
reaches initial set.
• Base thickness must be 1/2-inch (13 mm)
minimum for strength. This is measured from
the deepest part of the palate on the upper
(Figure 1c) or the "floor of the mouth" on the
lower (Figure 1d).
• After trimming, the base of the
model must be parallel to the
residual ridge (figures 1e and
• The base must be indexed for
mounting and remounting. Two
methods are shown here. Other
techniques are acceptable as
long as the index allows
accurate remounting of the
• The depth of the buccal sulcus is approximately 1-1.5-
mm below the land area. Positive defects (bubbles), if
any, must be in non-vital areas and small enough to
be easily removed (1-mm diameter or less as a guide).
• Negative defects (voids), if any, should be small and in
non-critical areas. These should be filled with stone to
blend with the surrounding anatomy.
• The master cast must include all anatomical surfaces
in the final impression.
– Should be safe to handle, compatible with
biological tissues & impression material, sufficiently
rigid to preclude distortion.
– Examples: Self-cured or light-cured acrylic resin
• Peripheral extension:
– Cover the entire denture-bearing area within the
anatomical limits previously described.
– 2mm short of the sulcus to allow for border molding.
– Should be formed to avoid encroaching on the
• Space for impression material:
– Should accommodate the optimum thickness of
the chosen impression material
• Irreversible Hydrocolloid: 3mm.
• Zinc oxide-eugenol : close fitting
• Poly vinyl siloxanes: depending on the viscosity
• Polyethers : 2-3mm
• Polysulphides: 2-3mm.
– Trays for complete dentures are requested without
perforations so that peripheral seal can be
• If no specific instructions are provided,
fabricate tray to the following standard: Outline
the tray 1-2 mm short of the mucobuccal reflection for both
upper and lower models. This will allow room for border
moulding material and save time for the clinician. The tray
must extend to the depth of the hamular notches on the upper
and should cover the retromolar pads on the lower . The lingual
extension on the lower should stop at the mylohyoid line in the
posterior and at the junction with the floor of the mouth in the
• Place relief material such as baseplate wax
to the outlined area and cut out three tissue
stops. Avoid placing a tissue stop over the
• The maxillary tray is made with 1 mm wax spacer and ends
short of the final tray extensions. On the maxilla, wax must not
cover the posterior palatal seal area. The mandibular tray is
made with no spacer(close fit)
• Tray is well adapted to the model with no voids.
• Tray must be of uniform thickness.
• Thickness must be sufficient in strength to prevent distortion or
breakage in use. The required thickness will vary with the
material used. In general, acrylic resin and similar materials
(such as light cure resins) should be approximately 2 mm thick,
and 1 mm short of the mucobuccal fold to allow for border
• The handle must be placed in the anterior so that it does not
interfere with placement of tray or border moulding
procedures. The handle may be placed approximately where
the wax rim or anterior teeth would be positioned on a
• Unless specified otherwise by the clinician, the tray borders
should be between 1 to 2 mm short of the mucobuccal
Custom Trays - Quality Failures
• Border extensions significantly longer or shorter than
• Tray not stable (flexible) due to insufficient thickness.
• Tray cracked or damaged.
• Improper handle position (interferes with border
moulding or insertion).
• Sharp and/or rough edges, which may irritate the
Base plates & Wax rims
cast (poured in
• Base plate:
– Self-cured or light-
cured acrylic resin.
– Wax rim
• (review lecture: Base
plates & Waxrims/3rd
Before complete dentures are constructed, the dentist
with the aid of the technician, must build a pro-forma or
template of the intended denture using-usually- wax
According to glossary of prosthodontic terms the
registration is ‘a record made of the desired
maxillomandibular relationship and is used to relate
casts on the articulator’
Maxillomandibular relationship is ‘ a relationship of the
maxilla to the mandible; any one of the infinite
relationships of the mandible to the maxilla’
In simple terms: the registration stage is 3-dimensional
prescription whereby the template of the intended
denture is ‘prescribed and fashioned’ clinically before
being dispatched to the laboratory for placement of the
teeth on the trial denture.
Unless the clinician has cast the definitive impression
and has scored the master cast to define the postdam,
the rim will not exhibit a clinically meaningful seal.
After immersing the rim in proper disinfectant material,
ensure that the rim is well adapted. Alternating finger
pressure on both sides of each rim should not elicit
Start with the upper rim- insert it and then ensure that
the infra-nasal tissues are harmonious with the soft
tissues of the middle third of the face. Failure to do so
may affect the form and length of the upper lip.
Confirm that the upper lip is adequately supported. This
should result in restoration of the vermilion border.
Determine the level of the incisal point relative to the
resting upper lip. Some text books recommend 2mm
below the resting upper lip level. Younger patients with
class II div I may require more(2-4mm) and older
patient ( over 70) may require the incisal level at the
level of the resting lip or 1mm above it.
The antero-posterior location of the incisal point can be determined by
asking the patient to say a word containing a fricative consonant, e.g. ‘fish’.
The incisal point should correspond to the vermilion border of the lower lip.
Determining the maxillary anterior & posterior plan:
The plan of the six anterior should be parallel to the inter-pupillary line.
Use a fox’s occlusal plane guide.
The posterior plan should be made parallel to ala- tragus line
The tips of the maxillary canines can be determined by extending a dental
floss from the inner canthus of the eye through the lateral border of alar
cartilage into the rim.
Using the mark on the rim corresponding to the canine tips, reduce the
inferior borders of the posterior rims by 3-5 ° to create the buccal corridors.
The customization of the upper rim is finished by scribing
High smile line
The above technique of customizing the upper rim is the one used at the
Dental Health centre-the one to be used by dental student. Another
technique to customize the upper rim is Swissedent technique (review
lecture on wax rims /3rd year).
Face bow transfer : depending on the case, the clinician may consider it
necessary to use a face-bow to transfer the relationship of the upper rim to
an arbitrary hinge axis. although it may not be strictly necessary to use a
face- bow in all cases, there is no valid objection to their use in the
prescription of complete denture.
Relating the mandible to the maxilla
Vertical (vertical dimension)
Sagital ( antero-posterior)
Coronal (left –right)
Resting Vertical Dimension (RVD)
Occlusal Vertical Dimension (OVD)
Affect tolerance and appearance
Free way space (RVD-OVD)
Select to measuring points in the midline of
the face-one relate to the nose and one to
the chin. These points must be on sites with
minimal influence from the muscles.
Ask the patient to moisten his or her lip and
bring them into light contact, then ask the
patient to swallow and relax his jaws
This is verified by asking the patient to
say the word ‘M’ while the
measurement is made.
Attention should be made to unwanted
skin movement. Use Willis gouge or
any other device-ruler- to measure the
distance between the two reference
points. This the RVD.
The maxillary & mandibular rims are
then inserted-after the upper rim has
been moulded- and the lower rim is
reduced in height- usually; or added to
if under sized) until it contacts the
upper rim evenly at a vertical
dimension of occlusion some 2-4mm
less than RVD
methods of determining vertical
-1. Boos: Bimeter (an oral meter that
-2. Silverman: closest speaking space-
looked at bicuspid area
-3. Pound: phonetics and esthetics
-4. Lytle: neuromuscular perception
-5. Pleasure: pleasure points (tip of nose
Retruded Contact Position
This visit is finished by
selecting the shade
determining the post
Selection of the mould & shade
Facebow transfer of the maxillary
• Mounting. (indexing)
• Setting the teeth
using the shade &
mould selected by
• Wax up and
procedures will be
Verify the appearance.
Verify the occlusal requirements.
( Please review lecture : try-in /3rd year)
Flasking, Packing and
finishing& processing of
1. Removal of wax
2. Replacing the wax mould
(hands- out summarizing this
laboratory procedures will be
Mirror those of the trial stage except
hopefully the patient is taking the
(review lecture on denture insertion/ 3rd
Arrange review visits for your patient as