Temporisation during Endodontics

Info

Temporisation is a critical phase in endodontic treatment that follows the initial investigation of a tooth, where existing restorations, caries, and cracks have been removed to assess its restorability. This process is more complex than simply filling a small access cavity, as it involves restoring a significantly compromised tooth structure to protect it throughout the duration of the root canal treatment and until the final restoration is placed.

Major Functions¹

Prevent bacterial ingress during and after treatment
Provide a sound base for rubber dam placement
This is essential for isolation, especially when treating the last tooth in an arch.
Protect against tooth fracture during treatment
However, any tooth structure likely to fracture should ideally be removed during the initial investigation phase.
Provide a stable reference point
This provides a consistent point on the occlusal or incisal surface for measuring file lengths (working length) that must not break or change between appointments.
Provide aesthetics where required

Key Considerations²

Temporisation involves the restoration of two distinct areas:

The Tooth
This involves building up the entire coronal portion of the tooth after the investigation phase (removal of old fillings, caries, etc.) is complete. This restoration provides the foundation for the entire treatment period.
The Access cavity
This refers to the filling placed within the access cavity of the interim restoration at the end of each treatment appointment to seal the canals between visits.

I. Interim Restoration of the Tooth³

This section addresses the restoration of the tooth structure itself, typically after previous restorations have been removed.

Info

This is the foundational build-up of a tooth, typically done at the first appointment following the complete removal of compromised tooth structure.

Materials and Techniques for Posterior Teeth⁴

Info

For posterior teeth (molars and premolars), which are subject to significant occlusal forces, a combination of robust materials is required.

Glass Ionomer Cements (GICs)⁵

Glass ionomer (e.g. Ketac Silver, Ketac Fil) is used for the interim restoration of the tooth, sometimes in conjunction with Stainless Steel (SS) bands.
Ideally, use traditional “chemical set” GICs for several reasons:
- Do not need to light cure
  - Can not light cure through a stainless steel band
- Minimal (? no) shrinkage
  - Especially in large cavities
Chemically-cured GICs do not contain composite resin, thus avoiding the polymerisation shrinkage associated with light-cured materials, which is a significant concern in large cavities.

Recommended GIC Materials

Recommended materials:
- Ketac Silver, Ketac Fil

Ketac Silver⁶

Preferred wherever possible
Historically this was the preferred material, though it is currently unavailable.
Colour contrast helps removal
- Can conserve more tooth structure
Stronger material - less brittle
- Esp. during later access cavity preparation
Less sensitive to moisture loss
- During setting
- Later when isolated with rubber dam

Ketac Fil⁷

Info

A tooth-colored GIC, making it the material of choice for aesthetic situations.

Used if an aesthetic restoration is required in areas such as:
- Upper and lower anterior teeth
- Upper 1st premolars
- Some lower premolars & upper 2nd premolars
A buccal “veneer” of Ketac Fil can be used if SS Bands are placed for retention of the temporary.

Application Guidelines for GICs (Ketac Silver and Ketac Fil)⁸⁹

Must follow the manufacturer’s instructions
Use dentine conditioner
- Retention: little difference
- Sealing: more reliable if conditioned
Use resin cover (Ketac Glaze) while setting
- For moisture control - in and out
==Band Placement (if used): Coat the inside of the fitted stainless steel band with the GIC material before seating it. The excess acts as a luting cement.==
==Bulk Fill: Use the remaining GIC to fill the cavity inside the band.==
Using dentine conditioner before applying GIC
Applying Ketac Glaze to help shape and protect the GIC
Use a cotton pellet held in tweezers and dipped in the glaze to shape and smooth the surface of the restoration. This is superior to using micro-brushes, which can create small 'pock marks'.
Achieving a smooth, well-contoured surface before the material sets is crucial, as it minimises the need for later trimming.

Stainless Steel (SS) Orthodontic Bands¹⁰¹¹

Main Function

To retain the interim restoration
This is especially important in extensively broken-down teeth where there is insufficient tooth structure for retention.

Other Functions¹²¹³

Prevent tooth fracture - “splint”
Base for rubber dam placement
Stable reference point for WL measurement
Assist with aesthetics
- e.g., For upper premolars with a missing buccal cusp, a buccal veneer of Ketac Fil can be placed over the band.

This can be improved by cutting retention holes in the buccal aspect of the band before placing the GIC.

In some cases: Allow long-term reassessment
Serve as a matrix for an amalgam core
The band is not suitable for composite cores, as it blocks the curing light.

flowchart LR
    A[Dental tooth preparation] --> B[Metal coping try-in on prepared teeth]
    B --> C[Finished metal copings]

Usage Statistics for Interim Restorations¹⁴¹⁵¹⁶¹⁷

Molars - 163 teeth

	Uppers	Lowers	%
Ketac Silver	12	8	12.2
Ketac Silver + SS Band	65	77	* 87.2
Temporary Crown	1	-	0.6

Note

Temporary crowns are rarely used due to instability.

Premolars - 52 teeth¹⁸

	Uppers	Lowers	%
Ketac Fil	3	-	5.8
Ketac Silver	10	5	28.8
Ketac Fil + SS Band	21	4	48.1
Ketac Silver + SS Band	1	8	17.3
Total with SS Band			65.4%

Note

The majority of ‘Ketac Fil + SS Band’ cases are upper first premolars requiring an aesthetic veneer. ‘Ketac Silver + SS Band’ is more typical in the lower arch.

Interim Restoration of Anterior Teeth¹⁹²⁰²¹²²

Info

Temporisation of anterior teeth often prioritises aesthetics and may involve different techniques, especially if a pre-existing crown and post have been removed.

Options after Post/Crowns Removed²³

CW / Cavit: deep in post hole
- Temp. post / crown - with IRM or ZnPO₄ cement
This is the preferred method. Weak cements like Temp-Bond are avoided as they lack adequate retention.
CW / Cavit in pulp chamber
- GIC over exposed dentine
- Temporary overlay denture
This is often used when multiple anterior teeth are being treated.
CW / Cavit in pulp chamber
- Temporary composite bridge bonded to root and to the adjacent teeth
Dressing Options:
- CW
- Cavit
- Temporary post
- Temporary crown

Usage Statistics for Anterior Teeth - 30 teeth²⁴²⁵²⁶²⁷

	Uppers	Lowers	%
Ketac Fil	11	4	50
Temporary Crown	14	1	50

Tip

The choice of restoration depends on the amount of remaining tooth structure.

II. Temporary Restoration of the Access Cavity (“Access Temporaries”)²⁸²⁹³⁰

This section addresses the temporary restoration of the access cavity between subsequent appointments.

Info

At the end of each appointment (after the initial one), the access cavity created through the interim restoration must be sealed. This is typically achieved using a ‘double seal’ technique.

Materials:
- Cavit
- IRM

Material Analysis: Cavit³¹

Composition

Calcium sulphate
Zinc oxide
Glycol acetate
Polyvinyl acetate
Polyvinyl chloride acetate
Triethanolamine
Red pigment

Properties and Performance³²³³

Advantage:
Convenience: Ready to use, no mixing required.
- Prevents moisture penetration
A thickness of at least 2mm is required for an effective seal.
- Materials include CAVIT and T.E.R.M. (Teplitsky & Meimaris - J Endod 1988)
Disadvantages:
- NO research reported about its ability to prevent bacterial penetration
- Poor strength
- Poor wear resistance
- High solubility

Supporting Research: Liberman et al. (2001)³⁴³⁵³⁶³⁷³⁸

Study: Effect of repeated vertical loads on microleakage of IRM and calcium sulphate-based temporary fillings. Liberman R, Ben-Amar A, Frayberg E. J Endod 2001; 27: 724-9.
Findings:
- “Passive” temporaries:
  - No difference in “seal” against radioactive tracer between IRM and calcium sulphate materials.
- With repeated occlusal loading:
  - IRM - no change
  - Calcium sulphate materials “deteriorated rapidly”
    - Penetration was “total and immediate”
    - “Equivalent to an open access cavity”
- Conclusion:
  - Also showed that penetration tests without occlusal loading are of limited, or no, value.
This demonstrates that Cavit is not suitable as a standalone temporary restoration.

Material Analysis: IRM (Intermediate Restorative Material)³⁹⁴⁰⁴¹

Composition

Info

Cavit is primarily composed of calcium sulfate (the main component of plaster). It is a single-paste material that sets upon contact with moisture.

Info

IRM is a reinforced zinc oxide eugenol (ZOE) material.

Caulk Dentsply IRM
- Zinc oxide
- Eugenol
- Reinforced
CONTENTS: 1 POWDER (38 G) 1 LIQUID (14 ML)
REORDER #610007
FOR DENTAL USE ONLY

Properties and Performance³²³³

Advantages:
- Prevent bacterial penetration
- High wear resistance
- Low solubility
These properties overcome the primary weaknesses of Cavit.
Disadvantage:
- Does not prevent moisture penetration

Mechanism of Action & Supporting Research⁴²⁴³

The ability of IRM to prevent bacterial penetration is supported by the following studies:

Hume’s diffusion studies
Brannström’s “upside down restorations”

Hume’s Diffusion Studies (‘84, ‘86, ‘87)⁴⁴

Eugenol is released by progressive hydrolysis.
Hydrolysis occurs at:
- External surface (saliva)
- Cavity floor (dentinal fluid)
ZOE Diffusion Concentrations:
The concentration is highest near the restoration (10⁻² to 10⁻³ M), which is antibacterial.
- The concentration drops as it nears the pulp (10⁻⁴ M), where it has an anti-inflammatory effect.
- 10⁻² M → Anti-bacterial
- 10⁻⁴ M → Reduces inflammation

Brännström’s “Upside Down Restorations” (1979)⁴⁵⁴⁶⁴⁷⁴⁸⁴⁹

Study: Brännström et al J Prosthet Dent 1979
Method:
- Human teeth in vivo
- Class V cavities were restored.
- Teeth were extracted.
- Examined histologically.
Experiment:
- Silicate restorations were placed to test the acid effect on the pulp.
- Silicate alone:
  - Pulp inflamed
  - Bacteria under restoration & in the tubules
This showed that bacterial leakage, not the material's acidity, caused the pulpitis.
- ZO-E cover over Silicate:
  - No pulp inflammation
  - No bacteria seen ZO-E Sil.
Conclusion:
- ZO-E prevented entry of bacteria into the cavities.

The “Double Seal” Technique⁵⁰⁵¹⁵²

Rationale

There is NO SINGLE IDEAL temporary filling material available for endodontic access cavities.
All of the available materials have:
- Advantages
- and Disadvantages
The “Double Seal” technique is used to combine the advantages and overcome the disadvantages of the materials available.

Layering⁵³⁵⁴

The

Rationale

The outer IRM layer resists wear and stops bacteria, while the inner Cavit layer stops any moisture that may get past the IRM from reaching the root canal system.

“Double Seal” is structured as follows from the base of the pulp chamber upwards:

Medicament
Cotton wool
CAVIT
*IRM

Tip

Ideally, the restoration should be approximately 50% Cavit and 50% IRM by thickness.

Role of Cotton Wool⁵⁵⁵⁶

Place a VERY SMALL pellet of CW over canal orifices.
Purpose:
- Prevents temporary filling going into the canals:
  - During placement of temporary, and
  - During removal of temporary
- Provides “matrix” / “stop” against which the Cavit can be placed
Failure to use cotton wool can lead to large gaps under the restoration or extrusion of material deep into the canals, complicating subsequent treatment.
Note:
- NO evidence that sterile CW allows bacterial penetration if adequate temporary placed

III. Summary of Required Materials⁵⁷⁵⁸⁵⁹⁶⁰

For Interim Restorations (Whole Tooth Build-up):
- ==Glass Ionomer Cements: Chemically-cured GICs like Ketac Silver (for strength and contrast) and Ketac Fil (for aesthetics).==
- ==Stainless Steel Orthodontic Bands: For retention in posterior teeth.==
- ==Temporary Crown Materials: For anterior teeth, including crown forms and materials like Luxatemp.==
For Temporary Restorations (Access Cavity Seal):
- ==Cavit: As the inner layer for its moisture seal.==
- ==IRM: As the outer layer for its wear resistance and antibacterial properties.==
- ==Sterile Cotton Pellets: As a crucial barrier over canal orifices.==

Cavit
IRM
Ketac Silver
Ketac Fil
St. steel orthodontic bands
Temporary crown forms
Cold cure acrylic resin
Temporary posts

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Temporisation during Endodontics

Major Functions1

Key Considerations2

I. Interim Restoration of the Tooth3

Materials and Techniques for Posterior Teeth4

Glass Ionomer Cements (GICs)5

Recommended GIC Materials

Ketac Silver6

Ketac Fil7

Application Guidelines for GICs (Ketac Silver and Ketac Fil)89

Stainless Steel (SS) Orthodontic Bands1011

Main Function

Other Functions1213

Usage Statistics for Interim Restorations14151617

Molars - 163 teeth

Premolars - 52 teeth18

Interim Restoration of Anterior Teeth19202122

Options after Post/Crowns Removed23

Usage Statistics for Anterior Teeth - 30 teeth24252627

II. Temporary Restoration of the Access Cavity (“Access Temporaries”)282930

Material Analysis: Cavit31

Composition

Properties and Performance3233

Supporting Research: Liberman et al. (2001)3435363738

Material Analysis: IRM (Intermediate Restorative Material)394041

Composition

Properties and Performance3233

Mechanism of Action & Supporting Research4243

Hume’s Diffusion Studies (‘84, ‘86, ‘87)44

Brännström’s “Upside Down Restorations” (1979)4546474849

The “Double Seal” Technique505152

Rationale

Layering5354

Role of Cotton Wool5556

III. Summary of Required Materials57585960

Footnotes

Graph View

Table of Contents

Backlinks

Major Functions¹

Key Considerations²

I. Interim Restoration of the Tooth³

Materials and Techniques for Posterior Teeth⁴

Glass Ionomer Cements (GICs)⁵

Ketac Silver⁶

Ketac Fil⁷

Application Guidelines for GICs (Ketac Silver and Ketac Fil)⁸⁹

Stainless Steel (SS) Orthodontic Bands¹⁰¹¹

Other Functions¹²¹³

Usage Statistics for Interim Restorations¹⁴¹⁵¹⁶¹⁷

Premolars - 52 teeth¹⁸

Interim Restoration of Anterior Teeth¹⁹²⁰²¹²²

Options after Post/Crowns Removed²³

Usage Statistics for Anterior Teeth - 30 teeth²⁴²⁵²⁶²⁷

II. Temporary Restoration of the Access Cavity (“Access Temporaries”)²⁸²⁹³⁰

Material Analysis: Cavit³¹

Properties and Performance³²³³

Supporting Research: Liberman et al. (2001)³⁴³⁵³⁶³⁷³⁸

Material Analysis: IRM (Intermediate Restorative Material)³⁹⁴⁰⁴¹

Properties and Performance³²³³

Mechanism of Action & Supporting Research⁴²⁴³

Hume’s Diffusion Studies (‘84, ‘86, ‘87)⁴⁴

Brännström’s “Upside Down Restorations” (1979)⁴⁵⁴⁶⁴⁷⁴⁸⁴⁹

The “Double Seal” Technique⁵⁰⁵¹⁵²

Layering⁵³⁵⁴

Role of Cotton Wool⁵⁵⁵⁶

III. Summary of Required Materials⁵⁷⁵⁸⁵⁹⁶⁰