Dentures Flashcards
Steps to denture construction
Primary impression Secondary impression w specialised tray Relationship bw maxilla and mandible and measurements are taken - wax registration blocks Wax model Denture fit Denture review
Anatomical structures of maxilla and mandible
Fovea palatini - at soft palate/hard palate interface
Hamular notch - marks distal border of denture where tensor palatini inserts into soft palate.
Pterygomandibular raphe.
Incisive papillae
Frenal attachments
External oblique ridge and mylohyoid ridge
Retromolar pad
Insertion of genioglossus and mentalis
Clinical techniques used when taking primary impressions
Firm pressure on premolar region
Border moulding
Extend impression tray by adding greenstick compound
Problems affecting the treatment (denture provision)
Age - can’t adapt to the new denture
Tooth loss
Alveolar resorption
patterns of alveolar resorption
Maxilla - moves palatally and gets shorter (buccal cortical plate resorbed)
Mandible - anteriorly moves lingually but posteriorly moves buccally bc of the mylohyoid ridge.
Mandible = 4x resorption as maxilla.
Effects of alveolar resorption
Loose dentures - add soft liner.
Decreased face height and angular chelitis.
Irregular = sharp protrusions that traumatise the soft tissues under and cause ulcers - surgically smooth bone.
Changes to occlusion e.g. crossbite and anteriorly incisal edge-to-edge contact.
Pain due to the mental foramen becoming superficial - use a soft liner.
Not enough resorption = thin denture that breaks often or denture that reduces the FWS/increases OVD
Factors that influence alveolar resorption
Systemic factors e.g. osteoporosis
Denture wearing
Anatomy e.g. retained roots or implants
Requirements of working impressions for patients with larger undercuts
Elastic material in a spaced specialised tray - can space certain parts of tray and use ZnO/Eug instead.
Requirements of a working impression for patients with no undercuts
Rigid material in a close-fitting specialised tray.
Use of ZnO eugenol for impressions
Mucostatic in a spaced tray or mucocompressive in a non-perforated close fitting tray.
Cheap, easy to use, accurate, good surface reproducibility.
Using alginate for impressions
Spread evenly in at least 3mm layer to prevent distortion
Using silicone for the impressions
For fibrous ridges + windowed tray, and for undercuts. Need a thickness of 1.5mm to avoid distortion.
What is a tissue stop used for
to ensure that the impression materials are at optimal thickness. Stops dentist over-pushing tray.
Use of an alma guage.
Indent in denture a incisive papillae. Measures distance from here to incisal edge and labial surface of incisal teeth - for wax blocks.
Verticle positions
RFH - don’t change
OFH
FWS = 2-4mm
increase OFH = decreased FWS.
Horizontal positions
ICP
RCP - most posterior position of mandible. Guided occlusal and first teeth to contact. Reproducible and reliable and based on anatomy.
CR - most anterior posterior position of condyle in fossa.
ICP = RCP is ideal.
Fox plane guide
Checks denture is parallel to interpupillary line and aga/tragus (Camper’s) line.
Clinical procedure for jaw relationship and registration stage
Verticle measurements
Horizontal measurements
Fox plane angles
Lip support and tooth positions (canine and midline)
Tooth shape, shade and size
Notch Upper and lower and use bite registration paste to hold them together in RCP.
What do u need to check for wax try-in
Teeth aesthetics and lip/soft tissue support Post-dam Tongue space Border extensions and thickness. OVD/OFH Occlusion/ICP Neutral zone balance
Info needed for lab at wax registration block stage
OVD RCP Occlusal plane Lip support Centre line
Curve of spee
Antero-posterior line
Curve of Monson
Lateral movement line
Occlusal balance for dentures during movement
Want ICP = RCP
Lateral movements need group function e.g. can’t rely on canines like normal dentition bc denture will tip.
Contacts on the non-working side
Problems with the post dam at wax try in stage
Over or under extended
Distortion of impression or denture = post dam pulls away at back so no seal. Cut deeper post dam on the model.
Faults to check for during insertion stage
Run cotton wool on the fitting surface to check for sharp bits.
Lateral and anteroposterior movements e.g. articulation and occlusion (BULL buccal upper lingual lower) - adjust cusps for articulation and fissures for occlusion (need to include first molars at least).
Check RCP = ICP
Retention
Overextended borders, post-dam
PSI paste on the inner surface and take an impression to see where the high points are - use vaseline bc sticks to mouth. Adjust these spots w a bur to reduce ulcers.
Instructions to give to patient after insertion stage e.g. when they first get the denture.
Ulcers and some pain is normal
Hygiene - clean mouth and denture and don’t sleep in it to prevent denture stomatitis/candida infections.
Common problems at review stage
Pain Insecurity/looseness Nausea Trouble speaking/eating Aesthetics
Pain at review stage caused by ..?
TMJ problems - poor occlusion or lack of FWS so always clenching.
Ulcers due to pressure spots
Trapping of tongue or cheeks if the denture is extended too far back or buccally.
Numbness bc denture pressing on mental foramen - add soft liner.
Insecurity/looseness of denture (review)
Due to trapped frenal attachments
Bad post dam/periphery seal.
Overextension or lingual undercuts from the teeth.
Can fix underextensions using self-curing acrylic.
Chewing problems (review)
Looseness or reduced FWS or occlusion problems (adjust the teeth contact points using articulating paper).
Can use gothic arch tracing to find CR.
Speech problems (review stage)
The patient can’t get used to denture or occlusion problems (lack of FWS, tongue cramping = lisp)
or looseness due to muscle interference.
Nausea (review stage)
Post-dam is too posterior or pressing down on the back of the tongue. Looseness can make nausea worse.
Denture faults at the insertion stage
Patient related - anatomy and local pathology
Lab - damage to models or poor processing
Clinician - lack of FWS, impression errors.
Removing pressure spots at post-insertion/review stage
Use dycal or ZnO directly onto the ulcer and then transfer to denture by taking imp and adjust that area, or use PSI paste if general.
How is retention of the denture caused
Suction (peripheral seal), adhesion and cohesion (saliva, wettability), muscular forces.
Problems with primary impression trays
A bad fit can cause over-extensions or thick uneven material = shrinkage and distortion.
What makes a good impression
Accurate reproduction of surface detail Viscosity Wettability Dimensional accuracy and stability Shrinkage on setting Cooling contraction Permanent set Storage stability Type of tray
How can you find CR
Gothic arch tracing
