Anti-Bacterial Strategies - Part 2¹

Winthrop Prof. Paul V. Abbott AO BDSc, MDS, DDSc, FRACDS(Endo), FPFA, FADI, FICD, FACD, FIADT

Specialist Endodontist Winthrop Professor of Clinical Dentistry UWA Dental School

Endodontic Medicaments²

Core Principles of Endodontic Anti-Bacterial Strategy

Aims of Endodontic Treatment³

To remove all micro-organisms from the root canal system
To remove all canal contents (organic or otherwise) that may lead to growth of micro-organisms or the breakdown of toxic products and their release into the periapical tissues
To prepare the canal for its disinfection and to develop a shape that permits a simple and effective root canal filling to be placed
To prevent micro-organisms from entering the tooth again and re-establishing infection in the root canal system as this causes apical periodontitis

Eight Essential Steps to Reduce Endodontic Microbial Flora

1. Identify and remove the cause
1. Aseptic procedures
1. Instrumentation / Mechanical instrumentation
1. Irrigants / Anti-bacterial irrigants
1. Medicaments / Intracanal medicaments
1. Interim and temporary restorations
1. Root canal filling
1. Coronal restoration

The Rationale for Intracanal Medicaments⁴

**Limitations of Instrumentation and Irrigation Alone

Mechanical instrumentation (filing) and chemical irrigation (e.g., sodium hypochlorite, EDTA) are effective at reducing bacteria in the main root canals. However, they have significant limitations in addressing the full complexity of the root canal system.

==Complex Anatomy: The root canal system is not a simple tube. It contains complex anatomical features that are inaccessible to instruments:==
- ==Isthmuses: Narrow connections between main canals.==
- ==Fins: Thin, wing-like extensions of the main canal.==
- ==Apical Deltas: A network of small, branching channels at the root apex.==
- ==Lateral Canals: Channels that branch off the main canal.==
==Dentinal Tubules: The dentine itself is porous, containing millions of microscopic tubules that can be heavily colonized by bacteria. Instruments cannot reach these tubules, and irrigants have very limited penetration (only a few microns).==

** Based on data from Byström & Sundqvist 1981, 1985 and from Sjögren & Sundqvist 1987, irrigation alone has limited efficacy in sterilizing canals.

Irrigant	% canals free of bacteria after one appointment
Nil	0
Saline	20
NaOCl	50
NaOCl + EDTA	70

Evidence of Residual Bacteria Post-Instrumentation⁵

**Viable bacteria in root dentinal tubules of teeth with apical periodontitis (Peters et al., J Endod 2001; 27: 76-81

This study demonstrated significant bacterial invasion into dentinal tubules in teeth with apical periodontitis.

Dentine was sampled at three depths: near the canal (A), midway (B), and near the cementum (C).

)**

A - 81% had bacteria
B - 60% had bacteria
C - 62% had bacteria
40% of samples with bacteria had >50,000 CFU’s/mg dentine

Key Takeaway

This indicates a high bacterial load deep within the dentine that cannot be physically removed.

Bacterial presence by section:
- A - 41%
- B - 41%
- C - 38.5%

**Microbial status of lower molars after “one-visit” endodontic treatment (Nair et al., OS:OM:OP:OR:Endo 2005

This histobacteriologic study examined teeth after instrumentation and filling in a single visit.

Even after preparation, significant debris and bacteria (stained black) remained in unprepared canals, isthmuses, and lateral canals.

)**

Results:
- 14 of the 16 teeth contained microbes - 88%
  - Cells were dividing indicating viability
- MLi canal (NiTi): 8 had microbes - 50%
- MB canal (hand): 8 had microbes - 50%
- 10 had microbes in the isthmus - 63%
- 5 had microbes in lateral canals - 31%
These areas are Inaccessible to Endodontic files.

Summary

This highlights that instrumentation and irrigation alone are insufficient to disinfect the entire root canal system.

The Necessity of an Inter-appointment Dressing (Byström & Sundqvist 1981, 1985; Sjögren & Sundqvist 1987)⁶⁷

OBSERVED:
- Bacterial numbers increased in the empty canals between appointments
CONCLUDED:
- An inter-appointment antibacterial dressing is necessary to predictably achieve canals that are free of bacteria

, particularly targeting the bacteria remaining in dentinal tubules and other anatomical complexities.

Primary Functions of Intracanal Medicaments⁸

Anti-bacterial action
- Residual bacteria in canals, tubules, fins, etc
- Contaminants between visits
- Periapical region
- Periodontal tissues
Reduce periapical inflammation
To prevent or reduce post-operative pain
Prevent or reduce pain
Stimulate periapical repair
To encourage healing of periapical tissues, either directly (through anti-inflammatory action) or indirectly (by eliminating bacteria)
Prevent or inhibit inflammatory resorption
To control both external and internal inflammatory root resorption

Evidence Supporting Multi-Visit Treatment with Medicaments

Improved Healing Outcomes⁹¹⁰

**Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis (Sjögren et al., Int Endo J 1997; 30: 297-306

==Treatment: One-visit endodontic treatment.==

)**

Results:
- All teeth were initially infected
- 22 (40%) still had bacteria after instrumentation
- Complete healing after 5 years:
  - 94% of cases with negative culture at RCF
  - 68% of cases with positive culture at RCF
  - 26% difference - statistically significant
Discussion:
- Emphasises the need to eliminate bacteria from canals prior to placing the RCF
- This can NOT be RELIABLY achieved with a one-visit treatment procedure
- Demonstrates - it is NOT possible to remove ALL organisms from root canals without the support of inter-appointment anti-microbial dressings

**Microbiological analysis of teeth with failed endodontic treatment and the outcome of conservative re-treatment (Sundqvist et al., OS:OM:OP:OR:Endo 1998; 85; 86-93

This study on endodontic re-treatment cases yielded similar conclusions.

==Treatment: Re-treatment of previously failed cases.==

)**

Results - Infection / RCF:
- 12% had microbes present at time of root filling:
  - Only 33% of these cases healed
(over 5 years)
- 88% no microbes present at time of root filling:
  - 80% of these cases healed
- This 47% difference was statistically significant

One- versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study (Vera et al., J Endod 2012; 38: 1040 - 1052)¹¹

(Study cited as evidence for single- versus two-visit treatment)

Pain Reduction

The relationship of intracanal medicaments to postoperative pain in endodontics (Ehrmann et al., Int Endod J 2003; 36: 868-875)¹²¹³

Study Design:
- 223 teeth - infected root canals with acute apical periodontitis
- RC instrumentation “to the apices” with 1% NaOCl + 15% EDTAC
- Ledermix paste, Ca(OH)₂ or no dressing
- Pain scores: Pre-op & for the next 4 days
Results:
- Ledermix group: Significantly less post-operative pain than the Ca(OH)₂ group and the control group
  - Started with higher average pre-op. pain score
  - At the 4 hours post-operative interval:
    - The greatest effect was noted
    - Pain level was well below the other groups
  - Pain level remained well below the other medicaments for the next 4 days
Conclusion:
- $⧫$ CONCLUDED: Ledermix paste is an effective intracanal medicament for the control of post-operative pain associated with acute apical periodontitis
- $⧫$ “The rapidity of action of the medicament with corticosteroid was striking”

Summary Conclusion for Infected Canals¹⁴¹⁵

So … when treating infected canals … Use two or more visits AND an intracanal medicament … to increase the PREDICTABILITY of periapical healing by destroying more bacteria and by changing the environment within the canal, PLUS to reduce post-operative pain and external inflammatory root resorption.

The Case for Multi-Visit Treatment in Pulpitis & Elective Endodontics

Note

While the need for medicaments in infected cases is clear, their use in vital cases (irreversible pulpitis) and elective endodontics is also strongly advocated.

Addressing Arguments for “One-Visit” Treatment¹⁶

Argument 1: “Canals not infected”¹⁷

$\to$ BUT consider what caused the pulpitis??
- Bacteria in the coronal part of the tooth
- 29% of pulpitis cases had bacteria isolated from samples taken from the root canal & pulp tissue
  
  Hashimura et al IEJ 2001
Therefore, an antibacterial agent is still beneficial.

Argument 2: “No apical periodontitis”¹⁸

$\to$ **BUT irreversible pulpitis often has primary acute apical periodontitis associated with it
This is indicated by symptoms like pain on biting and tenderness to percussion. A medicament with anti-inflammatory properties can help manage this periapical inflammation.

Example Case: Tooth 46: Acute Irreversible Pulpitis and 1° Acute Apical Periodontitis - due to Restoration Breakdown
- Symptoms: Sharp intense pain to heat, cold and biting; Intense pain 10-15 minutes then dull ache for ~1 hour; Worse when lying down; Woke patient during the night.
- Question: Is one visit OK ???

Evidence of Post-Procedural Inflammation and Pain

Periapical Irritation Even in Non-Infected Cases

Radiographic periapical healing after obturation of infected root canals (Katebzadeh et al., IEJ 2000)¹⁹

Negative control group: Not infected but root filled (Equivalent to “elective” endodontic treatment)
Result: 10% had small radiolucencies developing
- Irritation of periapical tissues from:
  - Mechanical procedures
  - Chemical materials - irrigants, RF’s, etc

Histological periapical repair after obturation of infected root canals (Katebzadeh et al., J Endod 1999)

Negative controls: not infected, normal pulps; aseptically cleaned & root-filled; one visit (Equivalent to “elective” endodontic treatment)
Result: Most cases still had mild periapical inflammation present after 6 months
- Indicates that endodontic procedures are irritating to the periapical tissues - Even if treating teeth with “normal pulps”

Neuropathic Pain and Neural Response to Pulpectomy²⁰

Consider: Removing the pulp implies severing the nerve fibres. This will invoke periapical inflammation, even when removing a “normal pulp”. (Holland GR - OS:OM:OP:OR:Endo 1995)

Neuropathic Pain Study (Lynch et al., J Orofac Pain 1996)²¹²²²³²⁴

Aetiology is not well understood
All cases followed a particular procedure / event
41% were related to root canal treatment
- But no detail re original diagnosis
Other causes: blunt trauma (23%), other dental surgery (12%), other local surgery (18%), other (6%)
50% had further dental surgical procedures
- But either no change in pain or the pain was worse

**Neural Response to Pulp Removal (Holland, 1995

==Severing a vital pulp invokes an inflammatory response in the periapical tissues, leading to a phenomenon called nerve sprouting.==

)**

The neural response to removing the pulp is a derangement of the plexus of nerves around the apical third of the root:
- Disorganised axon “sprouting” and branching
- Some features are similar to neuromas
This can cause prolonged post-operative discomfort, where the tooth 'feels different' or is uncomfortable for months or even years.
Normal neuron vs. Neuron - 2 weeks after being cut (Vickers - AEJ 2000)
Normal periapical region vs. Persistent inflammation - 3 months after RCF (Holland - 1995)
Stained to show nerves - 3 months after RCF (Holland - 1995)
Response differs after “natural amputation” (e.g. deciduous exfoliation, pulp necrosis). In these cases, healing occurs gradually and nerves grow out to innervate new target tissues (e.g. gingivae, bone, periodontal ligament).
Inflammatory and neural changes continue for at least one year after root canal treatment (Experiments done in cats, ? Humans - may be longer).
This can explain the “different sensation” / “discomfort” / “awareness” reported by some patients after endodontic treatment.
The neural and inflammatory responses can be greatly reduced - but not totally eliminated - by using **<span style=

Clinical Application

Crucially, Holland’s work showed that systemic corticosteroids could significantly reduce this nerve sprouting and inflammation. Placing a corticosteroid medicament directly in the canal offers a targeted, safer way to achieve this effect.

“color: 6cfd00;“>corticosteroids**. (Holland - used C-St’s systemically in cats; In humans - we can use intra-canal C-St’s).

**Pharmacological Management of Post-Operative Pain

A study comparing pain management strategies after treatment for irreversible pulpitis found:

==Oral Ibuprofen was more effective than a placebo.==
==Placing an intracanal corticosteroid (Dexamethasone) provided significantly greater pain relief than oral ibuprofen, especially from 12 to 48 hours post-operatively.==

Post-Operative Pain – Irreversible Pulpitis & Elective Endodontics (Rogers et al, J Endod 1999)
Time	Mean Pain Score		Mean Pain Score
Time	Ibuprofen (oral)	Placebo (oral)	Ibuprofen (oral)	Placebo (oral)	Dexamethasone	Ketorolac
6 hrs	~24	~36	~24	~36	~22	~18★
12 hrs	~20	~28	~20	~28	~12★	~10
24 hrs	~14	~22	~14	~22	~6★	~4★
48 hrs	~8	~20	~8	~20	~2★	~2★

Summary Conclusion for Pulpitis and Elective Cases²⁵²⁶

So … when treating pulpitis or electively removing “normal pulps” … Use two or more visits and an intracanal medicament … to reduce periapical inflammation, to reduce nerve sprouting, to reduce pain and to ensure no bacteria remain in the root canal system.

Types and Properties of Endodontic Medicaments²⁷

Medicament Choices and Major Functions

Function	Indication	Recommended Medicament
Anti-inflammatory	e.g. Acute Irreversible Pulpitis; Acute Apical Periodontitis	Ledermix paste
Anti-bacterial	e.g. Root-filled + infected RCS; Pulpless, infected RCS	Ledermix paste, Calcium hydroxide - Ca(OH)2
Stimulate hard tissue repair	e.g. Apexification	Calcium hydroxide - Ca(OH)2

Choices:
- Corticosteroid / antibiotic - CS / Ab
  - e.g. Ledermix paste
- Calcium hydroxide - Ca(OH)2
  - e.g. Calasept Plus paste
- 50:50 mixture - CS / Ab + Ca(OH)2
  - e.g. Ledermix + Calasept Plus
  - e.g. Ledermix + Pulpdent

Corticosteroid/Antibiotic Medicaments²⁸²⁹

Examples:
- Ledermix paste
- Odontopaste
- Septomixine Forte paste
- Pulpomixine paste
Literature Reviews (Abbott PV, Australian Dental Journal):
- Literature Review $\to$ 1990; 35: 438-48
- Guidelines for Clinical Use $\to$ 1990; 35: 491-6

**Odontopas

==Properties: A white paste, causing less discoloration than Ledermix. However, it has very little scientific evidence supporting its efficacy.==

te**

Similar to Ledermix paste
- But the AB is Clindamycin
- Also “1-2% Ca( $OH$ ) $_{2}$ ” - has varied (e.g. 5% originally)
Only one paper published in a journal
- Re: mixing with Ca( $OH$ ) $_{2}$ - but methodology was flawed & another study has been done to refute the findings
Provides an alternative for some cases
- e.g. If an infection is not responding
e.g. If discolouration is a concern
- e.g. If discolouration is a concern

**Ledermix Pas

Info

This is the preferred CS/Ab material due to extensive research and over 60 years of clinical use.

te**

$⋄$ Developed in 1960 (Prof. André Schroeder)
$⋄$ Commercially available since 1962
$⋄$ 52 years of research and clinical use !

Components³⁰

$⋄$ Triamcinolone - 1%
$⋄$ Demeclocycline - 3%
In a water soluble paste of:
The base is water-soluble for easy removal.
- $\to$ Triethanolamine NF
- $\to$ Calcium chloride USP
- $\to$ Zinc oxide
- $\to$ Sodium sulphite (anhydrous)
- $\to$ Polyethylene glycol 4,000 USP
- $\to$ Distilled water

Release and Diffusion through Dentine (Abbott PV, Hume WR, Heithersay GS, Endod Dent Traumatol 1988-1989)³¹³²

![](Red line graph showing Rate of Release on Y-axis and Time (Log scale) on X-axis.)

Rate of Release:
- Initially: Very rapid release
- Then: Slow, steady release
- Therapeutic amt’s up to ~6 weeks
==The corticosteroid is therapeutically effective for up to 6 weeks in mature teeth and 4 weeks in immature teeth.==
Triamcinolone (Corticosteroid):
- Measured peri-radicular concentration
- Detected in nanomolar range
- Sufficient for anti-inflammatory action
Concentrations of Demeclocycline in root dentine after Ledermix paste has been applied within the root canal:

	1 DAY	1 WEEK
	200	20
	20	2
	15	1.5
	200	20
	30	3
	15	1.5
micrograms/millilitre

Summary of Actions³³

Anti-inflammatory action
- reduces and prevents pain
- reduces “nerve sprouting”
Anti-bacterial action
- helps to reduce inflammation
- starts the healing processes
Inhibition of clastic cells
- reduces resorption of tooth and bone
Inhibition of PMN neutrophil collagenase
- reduces tissue destruction

Calcium Hydroxide (Ca(OH)₂) ³⁴

Commercial Preparations

Saline base
- Calasept Plus
- DT
Methyl-cellulose base
- Pulpdent paste
Powder - to mix with various liquids
Impregnated on GP points
- Roeko
==Note: Impregnated points are considered ineffective as they do not release sufficient hydroxyl ions.==

**Properties and Functions (Heithersay G, J Brit Endod Soc 1975

Mechanism of Action

Calcium hydroxide works by dissociating into calcium and hydroxyl ions, creating a high pH (alkaline) environment that is lethal to bacteria.

)**

Ca(OH)2 is the most widely-used endodontic medicament throughout the world.
Mainly because of its anti-bacterial activity.
Other very useful properties:
- Stimulates hard tissue formation
- Helps dissolve necrotic tissue
- Detoxifies bacterial endotoxin (LPS)
  - → Safavi & Nicholls 1993, 1994; Olsen et al 1999, Nelson-Filho et al 2002a, 2002b, Silva et al 2002, Jiang et al 2003, Tanomaru et al 2003

Inactivation of LPS (Tanomaru et al., IEJ 2003; 36: 733-9)³⁵³⁶

LPS $\to$ inflammation and bone resorption
- Stimulates macrophages to release cytokines (e.g. tumour necrosis factor, interleukins 1, 6, 8)
LPS was NOT inactivated by biomechanical preparation and irrigation with:
- Saline
- Chlorhexidine - 2%
- NaOCl - 1%, 2.5%, 5%
But LPS WAS inactivated by Ca(OH)₂

Limitations and Potential Problems

Toxicity - initial and long-term
The high pH that kills bacteria can also be toxic to host cells, potentially damaging the periodontal ligament if extruded from the canal.
Increased replacement resorption
Increased ankylosis
In rare cases, long-term use or extrusion can lead to ankylosis and replacement resorption, where the tooth root is replaced by bone.
May promote inflammatory resorption
==No Anti-inflammatory Action: It can initially cause some inflammation due to its toxicity and lacks the direct anti-inflammatory properties of a corticosteroid.==

50:50 Mixture - CS/Ab + Ca(OH)₂³⁷

Synergistic Effect

Combining Ledermix paste and Calcium Hydroxide offers a synergistic effect that overcomes the individual limitations of each material.

e.g. Ledermix + Calasept Plus
e.g. Ledermix + Pulpdent
Properties:
- Slower release of Ledermix paste components
  - Dressing lasts longer than Ledermix paste used alone → Maintains canal sterility for longer
- No change in activity of components
- Increased anti-bacterial spectrum compared to Ledermix paste used alone
- Only a small reduction in pH levels reached in dentine
- Lower tissue toxicity
  - Compared with $C a (O H)_{2}$
==Counteracts Toxicity: The corticosteroid in Ledermix helps to counteract the initial inflammatory toxicity of Ca(OH)₂.==

Clinical Application Protocols

Duration of Medicament Use³⁸³⁹

$⋄$ Absolute MINIMUM time: 2 weeks
- $\to$ Since inflammation takes 10-14 days to resolve
$⋄$ Most BENEFICAL and MAXIMUM times:
- Ledermix paste: $⌊ 4 \to 6 weeks$
- Calcium hydroxide: $⌊ 4 weeks \to 6 months$
- 50:50 Cs-Ab / Ca(OH) $_{2}$ mixtures: $⌊ 4 weeks \to 3 months$

**Rationale for Duration (pH Changes in Dentine

Rationale

Studies show that it takes 3 to 4 weeks for the pH within the dentinal tubules to rise and plateau when using Calcium Hydroxide. This high pH level (9-10) is necessary for effective bacterial killing and can be maintained for up to 3 months. Therefore, an appointment interval of at least 4 weeks is required to achieve the maximum antibacterial benefit of Ca(OH)₂.

)**

pH changes in root dentine (Nerwich et al JoE 1993)
- This study showed pH changes over 28 days for different parts of the root.

pH	Days
12	0
10	0.13
8	0.25
6	0.5
4	1
2	3
0	7
	14
	21
	28

pH changes in root dentine (Plataniotis & Abbott 1998)
pH Changes in root dentine - 50:50 Ledermix and Pulpdent pastes (Cai, Castro Salgado & Abbott - Aust Endo J 2018)
pH Changes - Ledermix with Calasept Plus or Pulpdent paste (Cai, Abbott & Castro Salgado - Materials 2018)

Application of Medicaments⁴⁰³⁹⁴¹⁴²

Preferred Method:
- ✅ Spiral filler: most effective & easiest method, ONLY if the canal has been enlarged.
It is used in a slow-speed handpiece in the forward direction to carry the paste apically.
Alternative Method:
- ✅ Hand file: If canal has NOT been enlarged / prepared.
The file is coated with paste and worked into the canal with a gentle pumping or counter-clockwise motion.
NOT Advised:
- ❎ Injection: No control; over-extension likely.
- ❎ Paper point: break down; periapical irritant.

Application of 50:50 Mixtures

Saline-based Ca(OH)₂ (e.g. Calasept Plus):
- ➤ Pre-mix on a glass slab.
- ➤ Then apply the mixture with a file or spiral filler.
Methyl cellulose based Ca(OH)₂ (e.g. Pulpdent):
Pre-mixing creates a thick, unworkable mass, so in-canal mixing is required.
- ➤ Place the CS / Ab in the canal first (with file or spiral filler).
- ➤ Then place the Ca(OH)₂ in canal - i.e. mix in the canal (with file or spiral filler).
Ca(OH)₂ powder:
- ➤ Pre-mix on a glass slab.
- ➤ Then apply with file or spiral filler.

Typical Multi-Visit Treatment Approach⁴³

First Appointment

Consult: history, exam $^{n}$ , radiographs, clinical tests
- Diagnosis - tooth, pulp/canal + periapical conditions
- Identify the cause(s)
Discussion, recommendations re: management options
L.A. and rubber dam (use cuff technique)
Remove ALL previous restorations
Remove ALL caries and cracked portions of teeth
Assess feasibility of endodontics and a new restoration
Access to the pulp chamber
- Pulpitis - pulpotomy or pulpectomy
- Infected canals - remove debris or existing RCF
Locate, negotiate & irrigate (EDTAC) all root canals
Root canal medication - depends on the diagnosis:
- Pulpitis - Ledermix paste
- Infected canal - 50:50 mix Ledermix + $Ca(OH)_{2}$
Close the pulp chamber - CW + Cavit
Interim restoration of tooth - usually GIC + band
Check and relieve tooth from all occlusal contacts
Post-operative instructions and discussion

Second Appointment - 4 weeks later⁴⁴

Check the tooth and surrounding tissues
L.A. and rubber dam (usually cuff technique)
Access cavity - through the interim restoration
Negotiate canals to estimated lengths
Establish “working lengths” - with radiograph(s)
Chemo-mechanically prepare the canals
- Irrigate - 15% EDTAC + 1% NaOCl + 15% EDTAC
The sequence is: EDTAC during filing, then Sodium Hypochlorite for disinfection, and a final rinse with EDTAC to remove the smear layer.
Medication - depends on original diagnosis:
- Pulpitis - 50:50 mix Ledermix + Ca(OH)2
- Infected canal - Ca(OH)2 alone
Close the access cavity - CW, Cavit and IRM

Third Appointment - 4 weeks (min.) later

L.A. is NOT required
- Sensitivity should alert the operator to a problem that requires correction before RCF completed - e.g:
  - Over-extension; Perforation; Pulp tissue left in canal; Insuff. irrigation - forcing medicament into P-ap. tissues
Rubber dam (cuff technique) and access cavity
Irrigate (EDTAC) + use smaller file than master file
==Irrigate thoroughly with EDTAC to remove all traces of the medicament. Do not use sodium hypochlorite at this stage, as this can create a new smear layer.==
Root canal filling - GP + AH 26
Close the access cavity - CW, Cavit + IRM
Final radiograph
Arrange final restoration and review appointments

Case Examples

The lecture concluded with several case examples demonstrating successful healing following a multi-visit treatment protocol using intracanal medicaments.

==Infected Canals: Cases showed significant bone healing of periapical radiolucencies over 3-6 months and long-term stability (e.g., 11 years).==
==Re-treatment: A previously failed case showed rapid and complete healing after re-treatment with proper disinfection.==
==Inflammatory Resorption: A case with external apical inflammatory resorption was managed with a longer-term medicament protocol, resulting in arrested resorption and bone repair.==
==Calcified Canals: A case with heavily calcified canals, where full instrumentation was impossible, demonstrated significant periapical healing. This highlighted the power of medicaments to disinfect areas that cannot be reached mechanically, by changing the canal environment to one that is inhospitable to bacteria.==

Pre-operative	RCF - 15 mths	4 yrs - Review

![](an image showing a sequence of four periapical radiographs demonstrating the treatment of mandibular incisors from pre-operative to 11 years review) Pre-operative RCF - 3 mths 6 mths - Review 11 yrs - Review

![](an image showing a sequence of three periapical radiographs demonstrating the treatment of a mandibular molar from pre-operative to 6 months review) Pre-operative RCF - 3 mths 6 mths - Review

flowchart TD
    A[Pre-op] -->|RCF - 3 mths| B;
    B -->|6 mths - Review| C;
    C -->|2 yrs - Review| A;
    
    D[Pre-operative] -->|WL| E;
    E -->|RCF - 18 mths| F;
    F -->|4 yrs - Review| G;
    E --> F;

Pre-operative

WL - PCC

3 mths - RCF

Anti-Bacterial Strategies - 2¹⁵⁴⁵⁴⁶⁴⁷⁴⁷

W/Prof. Paul V. Abbott AO

Pre-operative

WL - PCC
3 mths - RCF

$2^{n d}$ Year DMD - 2023

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L4 Anti-bacterial Strategies - 2 - Medicaments - 2023 - Handout_formatted_text

Anti-Bacterial Strategies - Part 21

Endodontic Medicaments2

Core Principles of Endodontic Anti-Bacterial Strategy

Aims of Endodontic Treatment3

Eight Essential Steps to Reduce Endodontic Microbial Flora

The Rationale for Intracanal Medicaments4

**Limitations of Instrumentation and Irrigation Alone

Evidence of Residual Bacteria Post-Instrumentation5

**Viable bacteria in root dentinal tubules of teeth with apical periodontitis (Peters et al., J Endod 2001; 27: 76-81

**Microbial status of lower molars after “one-visit” endodontic treatment (Nair et al., OS:OM:OP:OR:Endo 2005

The Necessity of an Inter-appointment Dressing (Byström & Sundqvist 1981, 1985; Sjögren & Sundqvist 1987)67

Primary Functions of Intracanal Medicaments8

Evidence Supporting Multi-Visit Treatment with Medicaments

Improved Healing Outcomes910

**Influence of infection at the time of root filling on the outcome of endodontic treatment of teeth with apical periodontitis (Sjögren et al., Int Endo J 1997; 30: 297-306

**Microbiological analysis of teeth with failed endodontic treatment and the outcome of conservative re-treatment (Sundqvist et al., OS:OM:OP:OR:Endo 1998; 85; 86-93

One- versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study (Vera et al., J Endod 2012; 38: 1040 - 1052)11

Pain Reduction

The relationship of intracanal medicaments to postoperative pain in endodontics (Ehrmann et al., Int Endod J 2003; 36: 868-875)1213

Summary Conclusion for Infected Canals1415

The Case for Multi-Visit Treatment in Pulpitis & Elective Endodontics

Addressing Arguments for “One-Visit” Treatment16

Argument 1: “Canals not infected”17

Argument 2: “No apical periodontitis”18

Evidence of Post-Procedural Inflammation and Pain

Periapical Irritation Even in Non-Infected Cases

Radiographic periapical healing after obturation of infected root canals (Katebzadeh et al., IEJ 2000)19

Histological periapical repair after obturation of infected root canals (Katebzadeh et al., J Endod 1999)

Neuropathic Pain and Neural Response to Pulpectomy20

Neuropathic Pain Study (Lynch et al., J Orofac Pain 1996)21222324

**Neural Response to Pulp Removal (Holland, 1995

**Pharmacological Management of Post-Operative Pain

Summary Conclusion for Pulpitis and Elective Cases2526

Types and Properties of Endodontic Medicaments27

Medicament Choices and Major Functions

Corticosteroid/Antibiotic Medicaments2829

**Odontopas

**Ledermix Pas

Components30

Release and Diffusion through Dentine (Abbott PV, Hume WR, Heithersay GS, Endod Dent Traumatol 1988-1989)3132

Summary of Actions33

**Calcium Hydroxide (Ca(OH)₂) **34

Commercial Preparations

**Properties and Functions (Heithersay G, J Brit Endod Soc 1975

Inactivation of LPS (Tanomaru et al., IEJ 2003; 36: 733-9)3536

Limitations and Potential Problems

50:50 Mixture - CS/Ab + Ca(OH)₂37

Clinical Application Protocols

Duration of Medicament Use3839

**Rationale for Duration (pH Changes in Dentine

Application of Medicaments40394142

Application of 50:50 Mixtures

Typical Multi-Visit Treatment Approach43

First Appointment

Second Appointment - 4 weeks later44

Third Appointment - 4 weeks (min.) later

Case Examples

Anti-Bacterial Strategies - 21545464747

Pre-operative

Footnotes

Graph View

Table of Contents

Backlinks

Anti-Bacterial Strategies - Part 2¹

Endodontic Medicaments²

Aims of Endodontic Treatment³

The Rationale for Intracanal Medicaments⁴

Evidence of Residual Bacteria Post-Instrumentation⁵

The Necessity of an Inter-appointment Dressing (Byström & Sundqvist 1981, 1985; Sjögren & Sundqvist 1987)⁶⁷

Primary Functions of Intracanal Medicaments⁸

Improved Healing Outcomes⁹¹⁰

One- versus two-visit endodontic treatment of teeth with apical periodontitis: a histobacteriologic study (Vera et al., J Endod 2012; 38: 1040 - 1052)¹¹

The relationship of intracanal medicaments to postoperative pain in endodontics (Ehrmann et al., Int Endod J 2003; 36: 868-875)¹²¹³

Summary Conclusion for Infected Canals¹⁴¹⁵

Addressing Arguments for “One-Visit” Treatment¹⁶

Argument 1: “Canals not infected”¹⁷

Argument 2: “No apical periodontitis”¹⁸

Radiographic periapical healing after obturation of infected root canals (Katebzadeh et al., IEJ 2000)¹⁹

Neuropathic Pain and Neural Response to Pulpectomy²⁰

Neuropathic Pain Study (Lynch et al., J Orofac Pain 1996)²¹²²²³²⁴

Summary Conclusion for Pulpitis and Elective Cases²⁵²⁶

Types and Properties of Endodontic Medicaments²⁷

Corticosteroid/Antibiotic Medicaments²⁸²⁹

Components³⁰

Release and Diffusion through Dentine (Abbott PV, Hume WR, Heithersay GS, Endod Dent Traumatol 1988-1989)³¹³²

Summary of Actions³³

Calcium Hydroxide (Ca(OH)₂) ³⁴

Inactivation of LPS (Tanomaru et al., IEJ 2003; 36: 733-9)³⁵³⁶

50:50 Mixture - CS/Ab + Ca(OH)₂³⁷

Duration of Medicament Use³⁸³⁹

Application of Medicaments⁴⁰³⁹⁴¹⁴²

Typical Multi-Visit Treatment Approach⁴³

Second Appointment - 4 weeks later⁴⁴

Anti-Bacterial Strategies - 2¹⁵⁴⁵⁴⁶⁴⁷⁴⁷