Non Surgical Re-treatment

Contents: Introduction Methods of retreatment Special considerations in retreatment Case selection Diagnosis Materials and techniques used for non surgical retreatment

Introduction

Retreatment is a method for treating POST TREATMENT DISEASE . Freidman indicated that most endodontic failures are related to post treatment disease.

Etiology of post-treatment disease Persistent root canal micro-organisms.(E.Facalis). Extra radicular infection (mainly, Actinomyces). Improper root canal treatment … over extended root filling accidental errors True cysts.

Methods of retreatment: 1- Non-surgical re-treatment (orthograde). 2- surgical retreatment(retrograde).

Special considerations in retreatment

Special considerations in retreatment There are unique considerations that distinguish non surgical retreatment from initial RCT : Extensive restorations have to be removed . Management of complex morphology as well as procedural errors. Removal of root canal filling materials. Longer follow up intervals are needed, since the healing rate is slower [persistent infections as E.facalis and C.albicans].

Retreatment is usually performed to treat existing disease, presenting with definitive signs and symptoms. However , even in the absence of disease, retreatment may be indicated to prevent its future emergence.

Case selection

Case selection Considerations governing case selection in the management of post treatment disease:(indications of retreatment) 1- Patient considerations. 2-Tooth related considerations. 3- Clinician related considerations. 4- Previous treatment attempts.

Patient’s attitude and motivation toward tooth maintenance. 1- Patient considerations. Patient’s attitude and motivation toward tooth maintenance. Financial aspects.

2-Tooth related considerations. Site of infection Vertical root fracture Accessibility to root canal system: canal blocks as calcifications broken instruments must be resolved to negotiate the whole root canal Presence of perforations worsen the prognosis .Internal repair is the first choice. Restorative and periodontal aspects

Skill Knowledge Advanced armamentaria time 3- Clinician related considerations. Skill Knowledge Advanced armamentaria time

4- previous treatment attempts. If previous surgical or non surgical treatment attempts was performed without significant improvement in the prognosis, other alternatives should be considered.

Diagnosis Subjective findings. Objective findings. Additional diagnostic tests. Radiographic examination.

Materials and techniques used for non surgical retreatment

1- Coronal de assembly

Removal of coronal restoration Coronal de assembly It involves access the pulp chamber through or after the removal of the coronal or extra coronal restoration Access made through the crown Removal of coronal restoration

Retain VS remove the restoration Gaining access through the original restoration: Facilitate rubber dam placement Maintain function and aesthetics Reduced cost

But, bulky coronal restoration leads to: Blocking the light transmission Increase the risk of irreparable errors due to altered anatomical land marks and inclination Improper isolation in case of poorly adapted margins Lack of radiographic information on the pulp champe

Remove the restoration if the visibility is affected, if the margins are poor and wouldn’t help in isolation or in the presence of recurrent decay.

Methods of coronal de assembly

2- Percussive instruments 1- Grasping instruments (crown tapper) 1- Grasping instruments {KY pliers}. 3-Active instruments (Metalift). 4- Sectioning.

2- post and core removal

(C) Loosen; (D) Retrieval 2 post and core removal The core is drilled away leaving just the post exposed from the canal. Weakening the post retention: 1- using ultrasonic vibrations (A) Post in tooth; (B) Make space; (C) Loosen; (D) Retrieval

2 -Post extraction using special devices (post remover system) Trephine bur to expose the post Extractor that engage the post head . Special plier applied to the extractor

The goal is to:

Complicaions Post space perforation Fracture of the tooth Fracture of the post

3- removal of the root canal obturation material

1- Gutta -percha 2- Removal of pastes.

1- Gutta –percha removal 1 Rotary removal Gates-Gliden bur removes the coronal GP. Rotary NITIfiles+ Hand files down the canal.

1- Gutta –percha removal 2 chemical removal Chloroform (not safe) Eucalyptol Orange peel oil

1- Gutta –percha removal 3 Thermal removal Heat carriers [System B] Combined with hand instruments

1- Gutta –percha removal 4 ultrasonic removal Generates heat facilitates removal with hand or rotary instruments

2- Removal of pastes. ZnO/Eugenol pastes ENDOSOLV-E(chloroform). Resin based pastes ENDOSOLV-R(chloroform). Calcium hydroxide pastes EDTA+ hand or rotary instruments. Hard setting pastes may need loosening with ultrasonic vibrations.

4 locating previously missed canals

How to diagnose Subjective findings

CBCT

Cross-sectional cone-beam computed tomography image of a mandibular first molar with a clearly distinguishable distolingual root. The purple arrows denote the mandibular first molar and the orange arrows denote the distolingual root.

Cone-beam computed tomography images showing the categorisation of the eight variants in mandibular second molars found . The white circles indicate the examined tooth

Knowledge of the tooth's internal anatomy

Complete reliance on the occlusal anatomy is dangerous because this morphology can change as the crown can be destroyed by caries and reconstructed by various restorative materials. Complete dependence on the occlusal anatomy may explain the occurrence of procedural errors like missed canals, perforation etc

Law of centrality: The floor of the pulp chamber is always located in the center of the tooth at the level of the CEJ. Law of concentricity: The walls of the pulp chamber are always concentric to the external surface of the tooth at the level of the CEJ. Law of the CEJ: The CEJ is the most consistent, repeatable landmark for locating the position of the pulp chamber. Law of Color Change: The color of the pulp-chamber floor is always darker than the walls. Law of symmetry 1: Except for maxillary molars, the orifices of the canals are equidistant from a line drawn in a mesial distal direction through the pulp-chamber floor

Law of symmetry 2: Except for the maxillary molars, the orifices of the canals lie on a line perpendicular to a line drawn in a mesial-distal direction across the center of the floor of the pulp chamber. Law of orifice location 1: The orifices of the root canals are always located at the junction of the walls and the floor. Law of orifice location 2: The orifices of the root canals are located at the angles in the floor-wall junction. Law of orifice location 3: The orifices of the root canals are located at the terminus of the root developmental fusion lines.

4 . Not centralized root canal filling

How to locate the missed canal ???? Observation of bleeding points. Champaign bubble test. Staining with methylene blue dye. Alternative application of 17% EDTA . Multiple angled pre treatment x rays . Magnification and illumination. Micro opener and micro debrider. Ultra sonic tips.

Magnification and illumination.

Endo-microscope Surgical operating microscope

Exploring as explorers and instrumentation as K file MICRO OPENERS Exploring as explorers and instrumentation as K file 7mm k type flutes 10 and 15 size with 0.04/0.06mm taper

Micro Debriders Flexible; stainless steel instruments Made for working with a microscope or other forms of magnification. They provide improved access to posterior teeth. Micro Debriders are designed for instrumenting difficult access canals or when visualisation of the canal is difficult.

5- management of procedural accidents

a. broken instruments Methods of removal: 1- GAINING ACCESS: to the broken instrument (straight line access using Gates glidden burs or Trephine burs.

Gates-Glidden is modified by removing their bottom half and thus creating a flat surface.

2-ULTRASONIC VIBRATION:( counter clockwise motion) to loosen the instrument. small tipped ultrasonic instruments can be used around the instrument and eventually vibrate the file out of the canal • Irrigation combined with ultrasonics can frequently flush it out at this point. • If sufficient file is exposed, an instrument removal system can be used.

Microtubes of instrument removal system 3- EXTRACTION FROM THE CANAL :(MICROTUBE systems- extractors ) Microtubes of instrument removal system

Prognosis of separated instrument depends upon following factors: • Timing of separation • Status of pulp tissue • Position of separated instrument • Ability to retrieve or by pass the instrument.

Studies have shown that instrument separation in root filled teeth with necrotic pulps results in a poorer prognosis. Also if instrument separates at later stages of instrumentation and close to apex, prognosis is better than if it separates in undebrided canals, short of the apex or beyond apical foramen.

It should be performed under sufficient MAGNIFICATION and preferably in straight roots.

If the extraction failed BY-PASS the instrument to be included in the final obturation (pre-flare with gates glidden and by pass with hand files

B -Perforations Methods of repair: Debridement and hemostasis Placement of barrier Placement of repair material( MTA- Bio aggregates)

(a–d) Clinical case of a lower molar showing an iatrogenic perforation of the pulp chamber floor. (e–h) Treatment of the defect with MTA and filling of the prepared root canals with gutta-percha. (i, j) Immediate postoperative radiographs. (k, l) One-year follow-up shows complete healing. (

Precautions to Prevent Perforation • Evaluation of the anatomy of the tooth before starting the endodontic therapy. • Using the smaller, flexible files for curved canals. • Do not skip the file sizes. • Recapitulation with smaller files between sizes. • Confirming the working length and maintaining the instruments within the confines of working length. • Using anticurvature filling techniques in curved canals to selectively remove the dentin

C-Transportation: Types : Internal transportation(Ledge):due to using non flexible instruments in curved canals at incorrect WL.

Ledge formation due to use of straight files in curved canal

Management Use a small file with a small bend at the tip of the instrument. penetrate the file carefully. Avoid use of chelating agents.

External transportation: moving the apical foramen into an iatrogenic position on the external root surface

causing ledge formation (2), zipping (3) or perforation (4).   The stiff instrument tends to straighten within the curved root canal (1), causing ledge formation (2), zipping (3) or perforation (4).

“Stripping” is a lateral perforation caused by over-instrumentation through a thin wall in the root and is most likely to happen on the inside or concave wall of a curved such as distal wall of mesial roots in mandibular first molars Stripping is easily detected by sudden appearance of hemorrhage in a previously dry canal or by a sudden complaint by patient.

External transportation Mild ….follow up Moderate and severe…surgical management. Successful repair of a stripping or perforation relies on the adequacy of the seal established by repair material. Access to mid root perforation is most often difficult and repair is not predictable. (MTA) or Calcium hydroxide can be used as a biological barrier against which filling material is packed.

6- Management of resistant infection Wide direct access, with canal enlargement beyond the previously prepared size, to remove residues of filling materials Proper irrigation with NAOCL5.25% and CHX 2 % Using calcium hydroxide intra canal medication for 2-3wks.