shortened dental arch Flashcards
What dental disease is common in RPD wearers?
- root caries
- periodontal disease
Why is dental disease common in RPD wearers?
Patients are already higher risk
What is the Kayser 1981 concept?
- SDA concept
- dentition where most posterior teeth are missing
- stable and accepatble dentition, satisfactory oral function
- priority is given to maintaining anterior and premolar in one or both jaws
- sufficient capacity is achieved when 3 to 5 occlusal units are left
What is an occluding unit?
- pair of occluding premolars = 1 unit
- pair of occluding molars = 2 units
What symptoms are associated with loss of molars?
- reduced masticatory efficiency
- mandibular displacement
- alteration in food selection
- aesthetic issues
- loss of occlusal stability
- TMJ problems
What are the indications for SDA?
- missing posterior teeth with 3-5 OU remaining
- sufficient occlusal contacts to provide occlusal table
- favourable prognosis for anterior teeth
- patient not motivated for complex Tx plan
- limited financial resources
What are the contraindications for SDA?
- poor prognosis for remaining dentition
- untreated or advanced perio
- pre-existing TMD
- pathological tooth wear
- significant malocclusion
What considerations should be taken before SDA?
- any problems chewing food?
- any appearance or cosmetic issues with anteriors?
- any discomfort?
- any evidence of occlusal instability?
What should be examined EO for an SDA?
- signs of TMD (click/crepitus/pain)
- hypertrophy of MOM
- skeletal relationship
What should be examined IO for an SDA?
- signs of bruxism (buccal keratosis/wear)
- periodontal assessment
- occlusal assessment
- teeth of poor prognosis
How should the occlusion be assessed for SDA?
- severe class II and class III are contraindicated as they have few OU
- edge to edge is okay
- 3-5 OU ideal
Why does significant periodontal disease contraindicate an SDA?
- drifting of periodontally involved teeth under occlusal load
- loss of alveolar bone leads to a compromised denture bearing area (long term) and
- loss of neutral zone
Describe pathological periodontal tooth movement in an SDA.
distal tooth migration occurs
- increased anterior load
- increased occlusal intensity
- increased interdental spacing
- exacerbated by inadequate periodontal support
Why is progressive tooth wear a contraindication for SDA?
- long term threat to prognosis of teeth
- gradual loss of occluding contacts and stability (loss of centric relation)
Define occlusal stability.
Stability of tooth positioning relative to its spatial relationship in the occluding dental arches
What are the five requirements of occlusal stability for SDA?
- stable contacts on all teeth in centric relation
- anterior guidance in harmony with envelope of function
- disclusion of all posterior teeth during mandibular protrusion
- disclusion of posterior teeth on non-working side during lateral excursion
- disclusion of posterior teeth on working side during lateral excursion
What is occlusal stability determined by?
- absence of pathology
- periodontal support
- number of teeth
- ID spacing
- occlusal contacts
- mandibular stability
What are manifestations of a traumatic occlusion?
- fracture of restorations or teeth
- mobility
- pain not explained by infection
- tooth wear
- TMD
How can the SDA be extended?
- distal cantilever RRB
- conventional distal cantilever bridge
- implants (+/- cantilever bridge)
- RPD (no longer SDA)
Where are RRB more successful in extending the SDA?
- distal cantilever
- lower more successful
- light occlusal load and less load during excursion
- max one unit
What causes a flabby ridge?
- Concentration of forces in anterior causes resorption of bone
What is combination syndrome?
- Complete upper denture + SDA lower
- flabby ridge - Upper Anterior
- conc of occlusal force upper anteirorly
- instability
- consider extension of SDA - denture (transitional)
- maintaining the SDA in the lower is usually transitional until lower teeth XLA
