Temporary crowns Flashcards
Why do we place temporary crowns after tooth preparation?
Temporary crowns 🦷 serve as provisional restorations placed after tooth preparation and before the final crown is cemented. They’re essential for:
🔐 Protecting the tooth:
Covers exposed dentine, which has high dentinal tubule density
Prevents fluid flow in tubules, reducing sensitivity and pain (hydrodynamic theory of pain)
🦠 Preventing bacterial invasion:
Acts as a barrier to bacteria and other irritants
🦷 Maintaining tooth structure & position:
Prevents overeruption of the prepped tooth
Prevents tipping or drifting of adjacent teeth which can affect occlusion and interproximal contacts
🩸 Managing gingival health:
Prevents soft tissue overgrowth over margins
Reduces gingival bleeding and inflammation
🎭 Restoring aesthetics and function:
Especially important in anterior regions
Allows patient to maintain smile confidence, speech, and normal function
🧪 Testing diagnostic changes:
Trial for occlusal scheme adjustments
Test changes in aesthetic appearance (e.g., incisal length or tooth contour) before final crown is made
What are the specific uses and benefits of temporary crowns?
🛡️ Temporary crowns serve to:
🔒 Prevent:
Dentine hypersensitivity
Bacterial ingress into tubules
Overeruption of prepped tooth
Drifting/tipping of adjacent teeth
Gingival overgrowth around prep margins
🎨 Restore:
Aesthetics – maintain smile and natural look
Function – chewing, speech
Contact points – avoid spacing or food traps
🧠 Assess:
Aesthetic changes (e.g., altered tooth shape, shade)
Occlusal scheme – vertical dimension, centric contacts
👨⚕️ Clinicians also use temporary crowns to evaluate patient tolerance to the proposed final design and function before proceeding.
What are the ideal properties of a temporary crown?
The perfect provisional crown should be:
🎨 Aesthetic – blends well, especially in visible areas
💪 Strong – withstands chewing forces for 2–4 weeks
🧩 Restorative – maintains proximal contact points to prevent tooth migration
🧼 Smooth and accurate margins – to minimize plaque accumulation and irritation
🧲 Retentive but removable – stays secure but can be removed easily for final crown placement
🧪 Biocompatible – does not irritate gingiva or pulp tissues
🧽 Polishable – so it doesn’t stain or feel rough to the tongue
What are the 3 main methods of fabricating temporary crowns?
There are 3 types, each with its own clinical use case:
1️⃣ Direct Custom-Made (Chairside)
Made on the patient using a pre-op mold
Uses bis-acryl composites like Integrity
Fast and cost-effective, used for short-term use
2️⃣ Prefabricated Crowns
Ready-made in standard sizes and shapes
Made of polycarbonate (anterior) or metal (posterior)
Can be adjusted and relined chairside
3️⃣ Indirect Laboratory-Made
Fabricated in the lab on a model using PMMA acrylic
Ideal for longer-term temporaries (3–4+ weeks)
Offers superior strength, fit, and polishability
How is a direct custom-made temporary crown made chairside?
🛠️ Steps:
Before prep: Take an impression or putty index of the tooth in its natural state 🧱
Prepare the tooth (crown prep) 🦷
Inject bis-acryl composite (e.g., Integrity) into the index and reseat it on the prep 🧴
Wait for it to set (~2–3 mins), then gently remove
Trim excess, adjust occlusion, and polish
Cement with temporary cement
💎 Advantages:
Accurate fit due to pre-op mold
No need to mix material
Repairs easily with composite
⚠️ Limitations:
Granular finish
Poor stain resistance
What is a diagnostic wax-up, and when is it used for temporaries?
A diagnostic wax-up is a lab-created model showing how the final tooth or teeth should look after treatment. 🕯️
📌 Used when:
Tooth is broken down or poorly shaped
Aesthetic or occlusal changes are needed
Planning restorative changes (e.g., increased incisal length, closing diastemas)
🧰 Helps to:
Guide the prep
Create a mold for a temporary that mimics the desired final shape
Show the patient what the final result might look like
What are prefabricated temporary crowns and their pros and cons?
Prefabricated crowns are preformed restorations selected chairside.
📦 Common types:
🦷 Polycarbonate (anterior teeth)
🧱 Aluminium (posterior)
🛠️ Stainless steel (posterior; mostly used in paediatrics)
🧪 Advantages:
Durable and time-saving
Good for emergency use or quick temporisation
Relined with Integrity for improved fit
⚠️ Disadvantages:
Poor contact points – can lead to drifting
Sharp margins – may irritate gingiva
Poor aesthetics – especially metal types
Possible metallic taste
What is the indirect lab-made technique for temporaries and when is it used?
👩🔬 Indirect technique is used when a stronger, longer-lasting temporary crown is needed (3–4+ weeks).
🧱 Process:
Take pre-op impression
Pour a model
Technician does a minimal prep on the model
Crown is made using heat-cured PMMA (Poly Methyl Methacrylate)
Sent back to clinician
Final tooth is prepped and the temp crown is adjusted and cemented
✅ Advantages:
Superior strength and aesthetics
Good marginal fit
Can be polished to high shine
⚠️ Limitations:
Requires 2 appointments
More expensive and time-consuming
What cements are used to fix temporary crowns and why?
🦷 Temporary crowns are cemented using temporary cements that provide adequate retention but can be easily removed:
🧴 Zinc Oxide Eugenol (ZOE) (e.g., TempBond):
Soothing on pulp
Good seal
Easy removal
⚠️ Not compatible with resin bonding later
🧴 Non-Eugenol Zinc Oxide:
Used when final crown will be bonded with resin cement
Prevents inhibition of polymerisation
Why is methyl methacrylate not used directly in the mouth?
⚠️ Methyl methacrylate is not suitable for intraoral use because:
🧨 Highly exothermic – generates heat that can damage pulp
📏 Large shrinkage – leads to poor fit
☣️ Chemical fumes can be irritating
Instead, it’s used indirectly in the lab, where it’s heat-cured and safe.
What is Integrity, and what are its key properties, uses, and limitations?
Integrity is a bis-acryl composite resin used for temporary crowns, bridges, inlays, onlays, and veneers in direct chairside techniques.
🔬 Properties:
⚡ Self-curing, quick set (~2 mins)
🎨 Tooth-coloured, polishable
🦷 Low shrinkage, low exothermic reaction
🛠️ Uses:
Temporary crowns, bridges, veneers
Reline prefabricated crowns
Trial restorations for occlusal/aesthetic changes
✅ Advantages:
✨ Aesthetic & polishable
💪 Strength for short-term use
🔧 Repairable with composite
⚠️ Limitations:
💥 Brittle in heavy occlusion
🧼 Granular texture, less stain-resistant
🕒 Not for long-term use (>3-4 weeks)
