The shortened dental arch Flashcards
What is the SDA Concept?
- Proposed by Kayser 1981
- A dentition where most posterior teeth missing
- Satisfactory oral function without use of RPD
- Priority given to maintaining anterior and premolar dentition in one or both jaws
- In right circumstances , non replacement of posterior missing teeth can provide stable and acceptable dentition
What is the definition of occlusal stability?
- Absence of the tendency for teeth to migrate other than the normal physiological compensatory movements occuring over time
- Or The stability of tooth positioning relative to its spatial relationship in the occluding dental arches
What factors determine Occlusal stability?
- Periodontal support
- Number of teeth in dental arches
- Interdental spacing
- Occlusal contacts
- Tooth wear
In the SDA concept what gives sufficient adaptive capacity?
- Gives sufficient adaptive capacity when 3-5 occlusal units are left
What classifies as 1 unit in SDA concept?
- Pair of occluding premolars
What classifies as 2 units in SDA concept?
- Pair of occluding molars
What are loss of molars associated with (in terms of problems)?
- Reduced masticatory efficiency
- Mandibular displacement
- Alterations in food selection
- Aesthetic issues
- Loss of occlusal stability
- TMJ problems
What is the 1992 World Health Organisation statement on amount of teeth we need?
- “the retention, throughout life, of a functional, esthetic, natural dentition of not less than 20 teeth and not requiring recourse to prostheses should be the treatment goal for oral health”
What are the indications for a txt plan with application of SDA?
- Missing posterior teeth with 3-5 OU remaining
- Sufficient occlusal contacts to provide large enough occlusal table
- Favourable prognosis for remaining anterior and premolar teeth
- Pt not motivated to pursue complex txt plan
- There are limited financial resources for dental
When will SDA work long term?
- Only work long term if remaining natural dentition can be preserved for remainder of lifetime of pt
What are the contraindications for application of SDA concept in txt plan?
- Poor prognosis for the remaining dentition
- Untreated or advanced periodontal disease
- Pre-existing temporomandibular joint dysfunction
- Signs of pathological tumour
- Pt has significant malocclusion i.e. Severe Class II or Class III
If any one of these are met then consider replacing posterior teeth
If you have broken down dentition what are the two options for txt plan?
- Restore complete dental arches (28 teeth)
- Restore reduced dental arches (SDA:20-24 teeth)
What are the pros and cons of restoring complete dental arches?
- More complicated txt
- Higher cost
- Too expensive for many pt or health care systems
- Better results?
Pros and cons of restoring reduced dental arches?
- Less complicated txt
- Lower cost
- Applicable for more pt
- Txt result worse perhaps?
What are some considerations you have to make about pt when deciding to adopt the SDA concept or restore full dentition?
- Does pt have any problems chewing food?
- Does pt have appearance or cosmetic concerns from missing teeth?
- Does pt have discomfort arising from missing teeth?
- Any evidence of occlusal instability as result of missing teeth?
If yes to any one of these then consider replacing missing teeth
Upon extra oral examination what are some keys things to look out for?
- Check for signs of TMJ dysfunction like click/crepitus/deviation/pain
- Hypertrophy/tenderness of MOM
- Skeletal relationship
Upon intra oral examination what are some key things to look for?
- Signs of Bruxism like buccal keratosis/ scalloping/ trauma/ wear facets/ restorations
- Signs of tooth wear
- Periodontal assessment
- Occlusal assessment
- Teeth of poor prognosis
What is the course of action if pt has periodontal problems?
- Course of non-surgical peridontal management should be planned
- Therpay aimed at stabilising periodontal condition of remaing teeth
- Evaluate response
- Must be able to maintain perio health
What are the negative consequences of failure to establish stable periodontal health?
- Drifting of periodontally compromised teeth under occlusal load
- Loss of alveolar bone leading to compormised denture bearing area in long term
- Loss of space (neutral zone) for denture teeth in long term
What type of tooth migration occurs in SDA and what does this have an effect on?
- Distal tooth migration
- Increases anterior load
- INcreased number and intensity of anterior occlusal contacts
- INcreases interdental spacing
- Exacerbated by inadequate perio support
Why is progressive tooth wear a contraindication to application of SDA concept?
- Long term threat this poses to survival of teeth (endo txt - can it withstand forces e.g.)
- Gradual loss of occluding contacts and occlusal stability
What can occur if stabilising occluding contacts were to fail in SDA?
- Unplanned tooth loss may happen
- This can lead to loss of occlusal stability
- Undermines SDA and may require extensive prosthetic rehab
What are the 5 requirements of occlusal stability?
- Stable contacts on all teeth of equal intensity in centric relation
- Anterior guidance in harmony with the envelope of function
- Disclusion of all posterior teeth during mandibular protrusive movement
- Disclusion of posterior teeth on the non-working side during mandibular lateral movement
- Disclusion of posterior teeth on the working side during mandibular lateral movement
What are some consequences of traumatic occlusion?
- Fracture of restorations and/or teeth
- Tooth mobility
- Dental pain not explained by infection
- Tooth wear
- May also contribute to TMD
What is a stable dentition?
- If pt can achieve reproducible ICP without evidence of pathological manifestations of trauma (prev card)
How can the SDA be extended?
- Resin retained bridgework
- Conventional bridgework
- Implants
- RPD
How would you incorporate a Resin retained bridgework or conventional bridgework in extension of SDA?
- Distal cantilever
- Max one unit on each side of arch
- Light contact on cantilevered pontics in ICP
- Minimal contact in excursive movements
- Heavy contacts may lead to failure
How would you incorporate implants in extension of SDA?
- Single tooth in molar/premolar position
- Cantilever bridge
How would you incorporate RPD in extension of SDA?
- Bilateral free end saddle
- RPI design
- Consider with CU
- Non compliance be aware