How is age relevant to dentistry when fabricating dentures?
- Communication with pt: impaired vision, hearing and cognitive function.
- Ageing of the orofacial tissues
- Pt may be difficult to adapt to prostheses
- Medications and medical diseases such as xerostomia can impact denture wearing
What are the treatment options for edentulousness?
- No treatment
- Complete upper and/or lower dentures
- Teeth supported by overdentures
- Implant retained overdentures
- Implant supported fixed prostheses
What happens when all natural teeth are lost?
Anatomical changes: i/o - maximum bone loss of up to 3 months after extraction, continuous and irreversible bone loss, changes in the maxilla and mandible, changes between jaws
E/O changes: changes in upper lip, lower lip, facial profile on side view and face view
Physiological changes: loss of proprioception, decreased masticatory efficiency and incising efficiency, decreased swallowing efficiency and impacts on speech and pronunciations
Psychological factors: embarrassment, denial, depression, social isolation, impact on quality of life.
Atwood’s Ridge Classification
Class I: Dentate
Class II: immediately post-extraction
Class III: well-rounded ridge in height and width
Class IV: knife-edge ridge form, adequate in height but not in width
Class V: Flatform ridge, inadequate in height and width
Class VI: Depressed ridge form with some basal bone loss shown
Denture Bearing Areas of the Maxilla
Extent where denture will sit
- From hamular notch to hamular notch
- Buccal vestibule extending from buccal frenum to the hamular notch
- Full extent of the sulcus around
- Hard palate and rugae
- Maxillary tuberosity
- Alveolar mucosa and ridge crest
Denture bearing areas of the mandible
- Full extent of the lingual sulcus where the tongue sits
- Covering the retromolar pads
- Labial sulcus
- Buccal shelves
- Retromylohyoid space
Reasons for replacement of missing teeth
Aesthetics, function, comfort, speech, psychological
Factors contributing to denture stability
Retentive forces > displacing forces + Adequate support from denture bearing areas = stable dentures
Retentive forces for denture types
Retentive forces: offer resistance to vertical movement of denture away from underlying mucosa
- Muscular forces > muscular control
- Physical forces > saliva
Neutral zone
Area of minimum conflict where the forces of the tongue pressing outward are neutralised by the forces of the lips and cheeks pressing inward
How to maximise retentive forces?
During impression stages: accurate: impression, extension of custom trays, border moulding, extension of the impression surface to cover all denture bearing areas and fit and adaptation of impression to underlying mucosa and ridge.
During registration stage:
Denture and teeth are in neutral zone buccal and lingual polished surfaces are correctly shaped and converging in an occlusal direction, accurate occlusion and teeth position.
Use of bony undercut > change the path of insertion, use of denture fixatives, long-term soft liners and dental implants
Conditions involving the oral mucosa that can affect denture fabrication
- Denture stomatitis
- Inflammatory papillary hyperplasia of the palate
- Angular stomatitis
- Prominent fraenae
- Denture induced fibrous hyperplasia
Conditions involving the bone that can affect denture fabrication
- Pathology within the bone e.g. cyst
- Sharp irregular bone
- Proiminent maxillary tuberosities
- Tori
Stages of jaw registration
Maxillary rim
- Lip support - ensure nasiolabial angle is 90 degrees
- Lip height at rest
- Incisal height = interpupillary line
- Posterior occlusal plane parallel to the ala-tragus line
- Buccal corridors
- Centre lines
- Canine lines
- High smile lines
Adjust the lower rim to give appropriate lower lip and buccal support. Adjust the height with reference to the OVD (RVD-FWS). Trim the lower rim to establish even bilateral contact with the upper at the retruded contact position.
Add a post dam and use futarD to join upper and lower occlusal rims
Teeth selection: shade selection, mould, pt’s photograph
Biometric guide help assist with
tooth position
BULL Rule - refining occlusion
This is where you remove the premature contact points by trimming the buccal aspect of the maxillary teeth and lingual of the mandibular teeth.
