Inlay and Onlays Flashcards
💡 What are indirect restorations, and how do they differ from direct ones?
🧱 Indirect restorations are lab-fabricated restorations (e.g. inlays, onlays, crowns) placed after preparation and impression-taking.
📤 Direct restorations (e.g. composite/amalgam) are placed chairside directly in the cavity.
🦷 Indirect = stronger, better contacts, and longer-lasting for extensive defects.
❓ Why choose an inlay/onlay over a direct composite restoration?
✅ More durable 🛡️
✅ Better occlusal contact & contours 📐
✅ Ideal for wide cavities or cracked teeth 💔
❌ Avoids polymerisation shrinkage stress seen in direct composites 😤
✅ Aesthetic options (especially ceramic) 💎
Q3: 🧠 What are the two main types of indirect restorations discussed in posterior teeth?
🧩 Inlays – fit within the cusps
🧱 Onlays – cover one or more cusps, sometimes full occlusal surface
🩺 What clinical situations are ideal for inlays?
Small/moderate MO/DO/MOD cavities
Intact cusps 🔒
Contact point difficult to achieve with direct composite 🤷♀️
Low caries risk & good OH ✅
When aesthetics are important 🌟
B-L width <⅓, height:width ratio <1.1 📏
Sufficient enamel for bonding 🦷
🏗️ When would you use an onlay over an inlay?
Cracked/undermined cusps 🪨
Post-RCT (root-filled) teeth 💉
Large MOD restorations 🧱
Height:width ratio >1.1
Parafunction/bruxism signs 😬
Tooth surface loss (erosion/attrition) 🌊
Wanting conservative cusp coverage vs crown
🚫 When are inlays or onlays contraindicated?
Poor OH & high caries risk 🚫🦷
Insufficient enamel (can’t bond) 😥
Subgingival margins (difficult isolation) 🌧️
Uncontrolled parafunction 😬
Patients not motivated for complex treatments ❗
💥 What increases the risk of posterior tooth fracture?
Large MOD preps (thin walls)
Height:Base ratio >1.1 📐
Root-treated teeth w/o cuspal coverage 💔
Parafunction (bruxism) – scalloped tongue 👅, muscle hypertrophy 💪
Group function occlusion (more posterior contact) 🦷➡️🦷
🧩 What is Cracked Tooth Syndrome and how is it identified?
Common in heavily restored molars (esp. with large amalgams)
🩻 Symptoms: sharp pain on biting/release
💡 Seen using transillumination
Often non-crowned, root-filled molars
🪙 What are the pros and cons of gold inlays/onlays?
✅ Very strong & durable 🛡️
✅ Biocompatible & accurate fit 🔬
✅ Minimal wear to opposing teeth
❌ Poor aesthetics 😬
❌ Technique sensitive + cost 💸
💎 What are the pros and cons of ceramic (e.g. e.max)
✅ Beautifully aesthetic 💫
✅ Strong & durable 💪
✅ CAD-CAM compatible 🖥️
❌ Brittle (can fracture) ❗
❌ Must avoid placing in heavy occlusion/contacts ⚔️
❌ Needs excellent bonding technique 👩⚕️
🌈 What are the pros and cons of composite inlays/onlays?
A11:
✅ Cheaper & aesthetic 💸✨
✅ Easy to repair or adjust 🔧
❌ Less durable over time ❌
❌ May stain or wear faster 🎨
🔧 What are the basic principles of inlay/onlay prep design?
Divergent walls (6–15° taper) 🔻
Smooth, rounded internal line angles 🌀
No undercuts (for indirect fabrication) 🚫
Avoid placing margins in occlusal contact areas ❗
Maintain maximum tooth structure 🎯
What are the occlusal reduction depths for different materials?
Gold:
1 mm (non-functional cusp)
1.5 mm (functional cusp)
Chamfer margin ~0.5 mm
Ceramic/Composite:
1.5–2 mm occlusal clearance
Shoulder/chamfer margin ~1 mm
15–20° taper 🔺
🧼 What is important when taking an impression for an inlay/onlay?
Clean, dry field (isolation is critical) 🧼
Gingival retraction cord if needed 🧵
Use PVS for conventional impressions OR
🖥️ Intraoral scanning (Trios, iTero, CEREC)
🕓 What is the purpose of temporisation between prep & final cementation?
Maintain occlusion 🔄
Prevent food packing 🍞
Protect pulp 🧠💉
Maintain contact points & tooth position
Use: Integrity or similar temporary material 🧴
⛓️ What luting cements are used for gold restorations?
Zinc phosphate cement 🧪
GIC (Glass Ionomer Cement)
Relies on mechanical retention 🔩
🧲 What is required for adhesive cementation (e.g. ceramic)?
Etch, prime, and bond tooth surface
Use dual-cure resin cement (e.g. Panavia F, RelyX Ultimate) 🧴
Needs moisture control (isolation key!) 💧❌
Offers chemical retention + tooth reinforcement 💪
📊 Can you summarise key differences between an inlay and onlay?
