Construction of complete dentures - clinical steps Flashcards
What is the purpose of jaw registration?
Record the occlusal relationship (between maxilla and mandible in this case) to produce a prosthesis that is functional and comfortable
Define intercuspal position (ICP)
Position where the teeth are in maximum interdigitation, and it is usually the habitual bite of the patient
Define retruded contact position RCP
The position of the condyles in the most superior, retruded position in the glenoid fossa of the maxilla
Why is RCP used in jaw registration?
It is the most reproducible position when there is no ICP (edentulism)
Define occlusal vertical dimension (OVD)
Distance between an arbitrary point on the maxilla and the mandible when the patient is in ICP
Define resting vertical dimension (RVD)
Distance between an arbitrary point of the maxilla and the mandible when the patient is at rest
Define freeway space (FWS)
Interocclusal space between the teeth at rest and when the head is upright
Define balanced occlusion
Simultaneous anterior and bilateral posterior contact of teeth in centric and eccentric positions
Why is balanced occlusion important in complete dentures
Prevents dislodgement of the denture via tripodisation
What occlusion should be avoided in complete dentures?
Anterior guidance (incisal and canine)
What are the main steps in jaw registration?
- Check rims on cast
- Check upper rim alone and adjust
- Check lower rim alone then adjust according to measurements taken
- Take bite registration
- Shade and mould
What do you assess when the occlusal rims are on the cast?
Retention (fit), extension, stability
What types of material can the occlusal bases and rims be made of
- Wax and wire reinforced wax
- Acrylic bases
When can existing dentures be used in jaw registration?
Patient happy with aesthetics - can use copy denture
Use in OVD/RVD measurement if occlusion is good
List the steps you do to adjust the upper rim
- Labial and buccal support
- Occlusal plane adjustment
- Markings: length of teeth, midline and canine line
How to adjust labial support in upper rim
- Too bulky - remove wax 3-3
- Unsupported - soften wax, add it 3-3 until happy
How much of the upper incisors should be visible at rest
Around 1mm
Take into account pts age (less teeth showing as you age)
How to ensure the correct occlusal plane is translated to the occlusal rim?
- Parallel to interpupillary line
- Posteriorly parallel to the camper’s line (ala tragal)
How to mark the midline on the upper rim
Use the midpoint of the interpupillary line
Avoid midline of the face as it may be asymmetrical
Where do you mark the canine line
Inner corner of eyes/outer part of nose
What do you adjust in the lower rim
- Labial and lingual aspects to the rim is not dislodged on movement of lips or tongue
- Occlusal plane should lie just under the tongue posteriorly
- Trim until parallel with upper
- Trim to match planned OVD
How to get patient into RVD naturally
Lick lips and swallow, their lips should be slightly parted
What instruments do you use in RVD/OVD calculations
Calipers
Willis bite gauge
How do you calculate OVD
(RVD - FWS) = OVD
How many mm is FWS
2-4mm
How do you record the occlusal relationship after adjustments have been made?
- Cut notches into the rims
- Place upper rim in situ
- Bite reg material applied to lower rim
- Place lower rim in situ
- RCP until set
- Assess
List the types of bite reg materials
- ZOE
- Wax
- Silicone
List the + and - of ZOE as bite reg material
+ cheap, dimensionally stable, setting time reduced by adding warm water
- allergies, avoid if xerostomia, long setting, messy
List + and - of wax as a bite reg material
+ cheap and accessible
- hardens quickly which can cause propping open at the back
List + and - of silicone as a bite reg material
+ Dimensionally stable, good detail
- sets quickly, expensive
How should the occlusal bases and rims fit in the mouth
Should extend to the full sulcus depth and correct posterior extension (provided from secondary impressions) to be retentive
How can the ‘f’ sound help in placement of teeth
Incisal edge of upper incisors meets the dry-wet border of the lower lip - good position for incisal edges
Excess OVD means there is…
Insufficient FWS
Insufficient OVD means there is..
Too much FWS
What are complaints with excess OVD
MOM fatigue Excess show of lower teeth Clicking of teeth when speaking Strained appearance of lips Uncomfort or gagging Excessive trauma to tissues
What are the complaints with insufficient OVD
Ageing of the lower face (wrinkles, chin close to the nose, overlapping of corners of lips)
Insufficient occlusal force
Angular cheilitis
What are the aims of wax try in?
Verify occlusion, aesthetics, phonetics, comfort with the patient before the denture is processed
What are the types of biometric guides for tooth positioning (complete dentures)?
Extraoral
Intraoral (maxillary and mandibular)
What are the extraoral biometric guides for tooth positioning (complete dentures)?
- Camper’s plane for posterior occlusal plane
- Interpupillary line for occlusal plane
- Midline of face or IPL for dental midline
- Outer corner of alae for canine tips
- Lips for incisal edge positioning
- Width of nose is 4x bigger than the width of centrals
What are the maxillary biometric guides for tooth positioning (complete dentures)?
- Incisive papilla (8-10mm)
- Alveolar ridge - teeth placed buccal to this
- Palatal gingival vestige - position of posterior teeth
What are the mandibular biometric guides for tooth positioning (complete dentures)?
- Alveolar ridge posterior - central fossae should overlie
- Alveolar ridge anterior - teeth anterior to ridge
- Retromolar pad - occlusal plane level with anterior RMP
- Maximum convexity of the tongue - lat border of tongue rests on lingual cusps
How is tooth positioning determined by palatal gingival vestige
Distance between the vestige and labial/buccal surface of the teeth should be 6mm incisors 8mm canines 10mm premolars 12mm molars
How to make sure the head is in the right position when taking RVD calculations
- Frankfort mandibular plane angle should be horizontal
How do you use a willis bite gauge?
Measures from base of the nose to the underside of the chin
How do you use calipers?
Dot drawn on nose and chin
C/I if bearded patient
What can be used as an addition to occlusal relationships and why?
Facebow to help mount the maxillary cast to the articulation
What is special about posterior denture teeth and why?
They are narrow to increase masticatory efficiency
