Partial dentures 5 ; new Flashcards
What are the main problems posed by anterior saddles in partial dentures?
👀 Aesthetics: Black triangles, visible clasps
🎨 Tooth shade, shape, and position may not match natural teeth
⚠️ Black triangles occur due to undercuts on adjacent natural teeth
❌ Lateral incisors aren’t suitable abutments for support/retention
⛔ Anterior undercuts interfere with normal path of insertion
Why can’t dentures be inserted normally into anterior undercut areas?
📏 Normal path of insertion = perpendicular to occlusal plane
🧱 The denture flange can’t pass into the undercut area (solid barrier)
➡️ Results in loss of retention & black triangle spaces
What are the problems with a Kennedy Class IV upper denture?
⚠️ Lack of support
🤷 Lack of retention
🙈 Aesthetic issues
🦴 Path of insertion difficulty due to anterior bony undercut
How can you improve support for a Class IV denture?
🧩 Cover a larger surface area
🔩 Use a CoCr (cobalt-chrome) framework
⚙️ Add occlusal rests for better support
If UL1, UR1, and UR2 are missing, how would you design a denture?
❌ Avoid spoon dentures – minimal coverage = poor support
📉 Spoon designs lead to excess pressure on mucosa
🦷 No clasps on laterals – roots are small & can’t handle stress
✅ Consider:
💪 CoCr denture for tooth-supported design
🧼 Maintain gingival health through clearance
🤝 A collected denture (but gingival health may be compromised)
What is an altered path of insertion?
🔁 A different direction of denture placement, not perpendicular
🛠️ Used to get around undercuts like anterior bony ones
🎯 Helps improve retention & cover black triangles
What’s the difference between path of insertion and path of displacement?
↪️ Path of Insertion = Direction the denture enters the mouth
🔼 Path of Displacement = Direction it’s pulled away during function/gravity (usually perpendicular)
How does altered path of insertion help solve black triangle issues?
🛡️ Denture doesn’t drop into the undercut root area
🎨 Flange can now fill in the black triangles
⚠️ BUT – may open up triangles further back due to new path
How do we find the true undercut using surveying?
📏 Do 2 surveys:
Model flat (occlusal plane horizontal)
Model tilted (heels down)
➡️ True undercut = area below both survey lines
🦷 Flange retention is now possible in undercut areas!
What is indirect retention and why is it important?
📉 Prevents the denture from rotating or falling down at one end
📐 Works by placing a rest in front of the clasp axis
🔧 Acts as a resistance arm to tipping
What is the clasp axis?
➖ An imaginary line drawn through the retentive clasps
⚖️ Acts as the fulcrum for rotation of the denture
🚫 Anything in front of it drops down, so we add indirect retainers there!
What features increase the effectiveness of indirect retainers?
➕ Further from the clasp axis
🧱 Placed on hard, flat surfaces
↪️ Clasp tips should face forward to improve effectiveness
How can milled crowns help improve retention and support?
👑 Crowns are custom-shaped with built-in guide planes and rests
🧩 CoCr framework fits snugly against them
💡 Increases support, retention, and path control
What factors affect aesthetic outcome in anterior dentures?
🎨 Tooth colour
🔷 Shape
📏 Size
📐 Arrangement
➕ Overjet and overbite affect smile and facial profile
How do we determine the position of anterior teeth?
📝 Answer: 3 Stages:
💋 Lip support – Adjust wax to maintain a natural nasolabial angle (~90°)
🔽 Incisal level – Trim/add wax until right amount of tooth is showing
📐 Parallel to interpupillary line – Ensure smile isn’t sloping
How do we use wax rims for aesthetic positioning?
🕯️ Wax rims show where teeth will go
🔥 Adjust wax (heat and knife) for:
👄 Lip support
👇 Tooth length
↔️ Interpupillary alignment
How does the construction sequence change for anterior bounded saddles?
🔁 Normal sequence:
Primary impressions
Tooth prep & secondary impressions
Framework try-in
Record occlusion
Wax try-in
Fit
✳️ Anterior saddle sequence:
Primary impressions
Record occlusion
Wax try-in (to determine anterior tooth position 🎯)
Then tooth prep & secondary impressions
Try-in framework with anterior teeth (tech needs space info to make frame!)
Fit
