Major components Flashcards
What is cross arch stability?
resistance against dislodging or rotational forces obtained by using natural teeth on the opposite side of the dental arch from the edentulous space
Requirements of Major connectors:
- Must be Rigid
- Must provide vertical support and protect the soft tissues
- Must provide a means of obtaining indirect retention where indicated
- Provide an opportunity of positioning denture base whereneeded
- Maintain patient comfort
- Should not create food entrapment areas/as far as possible self cleaning
- Should not interfere with tongue/ should not cause irritation to tongue
- Should not impinge on oral tissues when the restoration is placed, removed, or rotates in function
- Should not cover more tissues than absolutely necessary
Maxillary & Mandibular Stress-Bearing areas
Maxilla:
1: firm tuberosities, hard palate on either side of palatal raphe
2: alveolar ridge, rugae
Mandible:
1: buccal shelves, retromolar pad
2: alveolar ridge
Areas Requiring Relief in Impression
2nd stress-bearing areas
- Palatal torus
- Median palatal raphe
- Mandibular tori
- Retromylohyoid ridge
- Undercuts or sharp bony prominence on ridges
Maxillary limiting areas:
- Labial frenum
- labial vestibule
- buccal frenum
- buccal vestibule
- hamular notch
- fovea palatine
- vibrating areas
Mandibular limiting areas:
- labial frenum
- labial vestibule
- buccal frenum
- Buccal vestibule
- lingual frenum
- Retromolar pad area
Basic Design Requirements:
- Rigidity
- Free gingival margin (FGM) 6mm
- Parallel and 90°
- Auxiliary role in indirect retention
- Round boarders
- Crossing midline at 90°
Free gingival margin (FGM)
6mm-> Because of blood supply or deep vascularity of the gingival crevice
- In the maxillary arch-the border of the major connector should be at least 6mm from the gingival crevice of the teeth.
- In the mandibular arch-it should be at least 3-4 mm from the gingival margin.
Types of maxillary major connectors:
- Single posterior palatal bar
- Palatal strap
- Anteroposterior, or double, palatal bar
- Horseshoe, or U-shaped connector
- Closed horseshoe, or anteroposterior palatal strap
- Complete palate
Single palatal bar or anterior and posterior palatal bars:
- Best avoided!
- Defined as such if <8mm wide
- Need to ensure rigidity results in increased bulk which is likely objectionable
- These cases would be better served by palatal straps
Single palatal bar:
Indications:
Advantages & Disadvantages:
Indications:
- Bilateral edentulous spaces of short span which is entirely tooth-supported
- Defined as such if ˂ 8mm wide
- Limited usage
Advantages:
- Minimum coverage
- Although most widely used but as an interim partial denture until more definitive treatment can be considered.
Disadvantages:
- Lacks rigidity
- It is frequently made either too thin and flexible or too bulky.
Palatal strap:
- Most commonly used in Kennedy Class II cases
- May be rigid without being too bulky, by curving antero- posteriorly and laterally
- Should not extend beyond the occlusal rests at either end
Indications:
- Bilateral edentulous spaces of short span in a tooth- supported restoration.
Single Palatal Strap:
Anterior and posterior palatal strap:
What are the advantages of palatal straps major connectors?
- Rigidity
- Midpalatal straps cause little interference with tongue, easily accepted by patients
Palatal plate:
- Defined as such when covering more than half of the palate
- Requires close tissue adaptation
- Aim to replicate the natural soft tissue contours of the palate
- As thin as possible
- May be extended posteriorly with addition of acrylic post palatal seal
Complete Palatal Plate:
U-shaped connector:
- Best avoided
- Not as rigid as alternative options
- Poor support
- Bulk necessary to enhance rigidity may interfere with tongue movements and not be well tolerated
