4. Aesthetics and jaw relation Flashcards
Registration of Aesthetic and Jaw Relationships
for complete dentures - clinical procedures
- Shape the rims as a template for tooth position and
occlusal planes. - Record the desired jaw relationship - RCP @
prescribed OVD to allow the casts to be mounted on an
articulator for tooth set up
How to complete the registration of aesthetics and jaw relationships
- Decide treatment plan
- Aesthetics (upper jaw) – copy / change / specifics
- Jaw relationship (lower jaw) – always record RCP -
most posterior position but what OVD?
Recording the desired shape of the rims
Replacement Dentures - use as template where possible
Use the satisfactory features of the previous dentures:
1. Lip support first (note tooth position relative to incisal
papilla and tooth proclination)
2. Incisal level at rest and function
3. Anterior and posterior occlusal planes
4. Width and form of arch
5. Mould and shade
Recording the desired shape of the rims - how?
Aesthetics-
- copy by eye, try to reproduce it
- trim rim against denture- trying to reproduce the arch form, the rounded form of the denture, the proclination of anterior teeth. This might require rim to have wax added to it or removed to achieve this
Jaw relation-
measurements i.e. Alma gauge (set point of spring element onto incisal papilla and decide how far forward the incisors are from it, also a scale for the height of teh denture, callipers
impression of old denture as template for set up (lower posterior teeth must go on the alveolar ridge and that dictates where the upper posterior teeth go
Final parts of aesthetics
Lip support
Oclusal plane
Centre line
Recording the desired shape of the rims- no previous dentures
Classic guidelines:
Lip support: tooth position – up to 1cm ahead of
incisal papilla
tooth inclination - 90° columella-philtrum angle
Incisal level: at rest and function - show 1 or 2
mms below lip at rest, nearly all the
crown when smiling but customise to
patient
width and form of arch: harmonise to patient facial profile, no
posterior buccal corridor
mould and shade: customise to patient
How to achieve good lip support?
Good lip support is achieved by correct anterior placement of incisors – not flange thickness …. making columella-philtrum angle 90 degrees
Labial surface of many natural central incisors are about 8-10mm from the centre of incisal papilla- make them so
When viewing upper denture the anterior teeth should be visible and the lab should not make the labial mucosa excessively thick to try and achieve good lip support ie meaning that you cannot see the teeth
What if you dont achieve good lip support?
Lower incisors will be too lingually placed and so will upper as a result to match this, both encroaching on tongue space…. making columella-philtrum angle less than 90 degrees
Occlusal plane?
trim using Fox’s occlusal plane indicator-
upper-
anterior occlusal plane parallel to interpupillary plane
posterior occlusal plane parallel to ala-tragal line (Campers
plane) through tragus of the ear to lower border of ala of nose
- this allows the occlusal forces applied to the dentures to be
perpendicular to the alveolar ridges which improves stability
lower occlusal plane should be below
the resting level of the tongue, runs into the retromolar pad
about half way up
Selecting teeth
- Same mould / shade as previous dentures
- Change with reference to previous teeth
- Shade guide (based on Vita porcelain guide)
A1-A4, B2-B4, C1-C4,D1-D4 - Round, square, tapering
- Photos, old partials, old study casts
Centre line
place in middle of exposed rim at rest/smile - ignore
nose!
Lower registration rim - ie. Recording the jaw relationship -
RCP
- The antero-posterior component
- The vertical component
Methods to record retruded position:
instructions to patient (relax mouth, relax jaw, curl tongue slowly to the back and top of the upper)
tongue retrusion
gentle guiding (bimanual mandibular manipulation- put index finger on the lower rim/ denture premolar area thumb slightly on the border of the mandible and gently guide- tell patient to let their jaw go loose and slack, close slowly on your back teeth
others: swallowing
fatigue muscles that protrude mandible i.e. lateral pterygoid
gothic arch tracing - intra-oral or extra oral
- point attached to one block traces
jaw movement, which resembles an arrow head or gothic arch, the
point of which indicates the most retruded position on a recording
plate on the other block, point on the arch is RCP
Gothic arch tracing (Central-bearing-point registration plates)
Plate with recording medium on
upper (or lower) rim
Stylus on lower (or upper)
Pt. instructed in jaw movements
RCP indicated by point of ‘arrow
head’ (rem. Horz. Jaw Tracing!)
No real practical value,
But some claim it to be objective
Recording RVD
- Aim: point of reference to calculate OVD
- Pt must be completely relaxed: allay anxiety,
relaxed manner, comfortable, upright, reduce
external stimuli, close eyes, get pt. to swallow / say
letter ‘m’ / lick lips - Willis bite gauge
- Two-dot technique
