Shortened dental arch Flashcards
What are the problems with RPD
High incidence of dental disease in partial denture wearers
-root caries
-periodontal disease
When was the SDA concept first looked at
Kayser 1981
What is a SDA
A dentition where most posterior teeth are missing
Satisfactory oral function without use of RPD
What is adaptive capacity
Sufficient adaptive capacity in subjects when 3 to 5 occlusal units are left:
-a pair of occluding premolars = 1 unit
-a pair of occluding molars = 2 units
What are the criticisms to SDA
Loss of molars associated with:
-reduced masticatory efficiency
-mandibular displacement
-alterations in food selection
-aesthetic issues
-loss of occlusal stability
-TMJ problems
What were the conclusions of Witter et al 1994
(i) SDAs provide sufficient oral function and oral comfort in terms of chewing function, aesthetics, and signs and symptoms of TMD
(ii) SDAs provide sufficient mandibular stability: the absence of molar support is not a risk factor for the development of TMD problems
(iii) SDAs provide sufficient occlusal stability: minor changes in interdental spacing occur shortly after extractions leading to an SDA, but a new occlusal equilibrium remains stable and these changes do not pose any problem to the oral function. Vertical overbite is not influenced by the SDA
(iv) Occlusal attrition in SDAs does not differ significantly from that of complete dental arches
(v) Alveolar bone height scores in SDAs tend to decrease at the same degree as in complete dental arches
What determines occlusal stability
tooth wear
Absence of pathology: tooth wear, periodontal disease
Periodontal support
Number of teeth in the dental arches
Interdental spacing
Occlusal contacts
Mandibular stability
What will patients with a SDA have compared to those that don’t
More interdental premolar spacing
greater occlusal contact of anterior teeth
lower alveolar bone scores
What are the indications of a SDA
Missing posterior teeth with 3-5 OU remaining
Sufficient occlusal contacts to provide a large enough occlusal table
Favorable prognosis for remaining anterior and premolar teeth
Patient not motivated to pursue complex Rx plan
There are limited financial resources for dental care
Whats important for a SDA to work
Remaining natural dentition can be preserved for th remainder of te lifetime of the patient
What are the contraindications for SDA
If there is a poor prognosis for the remaining dentition
Untreated or advanced periodontal disease
Pre-existing temperomandibular joint dysfunction
Signs of pathological toothwear
The patient has a significant malocclusion
-severe Class II or Class III
What consideration are there for a SDA
Does patient have any problems chewing
Does patient have any apperance or cosmetic concerns from the missing teeth
Does patient have any discomfort from the missing teeth
Is there any evidence of occlusal instability due to missing teeth
IF YES TO ANY OF THESE, REPLACE MISSING TEETH
On examination what should you check for
Extra-oral
Check for signs of TMJ dysfuntion:
click/crepitus/deviation/pain in TMJ
-hypertrophy/tenderness of MOM
-Skeletal relationship
Intra-oral
Check for signs of bruxism:
-buccal keratosis/scalloping/trauma/wear facets/ restorations
-Check for signs of toothwear
-Periodontal assessment
-Occlusal assessment
-Teeth of poor prognosis
What perio health would be accepted
If they require non-surgical treatment
Why is progressive tooth wear a contra-indication
-The long term threat this poses to survival of teeth
-Gradual loss of occluding contacts and occlusal stability
