Procedural error

Like other complex of dentistry, an operator may encounter unwanted or unforeseen circumstances during root canal therapy that can affect the prognosis.

These mishaps are collectively termed procedural accidents or procedural error.

When an accident occurs during root canal treatment, the patient should be informed about,
(1) The incident.
(2) Procedures necessary for correction.
(3)Alternative treatment modalities.
(4) The effect of this accident on prognosis.
Ethical point.

Classification of Procedural Accidents

Classification of Procedural Accidents

Perforations During Access Preparation

Causes
Prevention
Recognition and Treatment
Prognosis


Underfilling
Overfilling
Vertical Root Fracture

• Ledge formation

• Cervical canal perforations
• Mi-droot perforations
• Apical perforations
• Separated instruments and foreign objects
• Canal blockage
Accidents During Access Preparation
Accidents During Cleaning and Shaping
Accidents During Post Space Preparation
Accidents During Obturation

Accidents During Access Preparation

Perforations During AccessPreparation

• The prime objective of an access cavity is to provide an unobstructed or straight-line pathway to the apical foramen.
• Accidents such as excess removal of tooth structure or perforation may occur during attempts to locate canals.
• Perforations must be recognized early to avoid subsequent damage to the periodontal tissues with intracanal instruments and irrigants.


Perforations
• There are two types of perforation during access:
•

1. Lateral root perforation 2. Furcation perforation

Causes
• Failure to direct the bur parallel to the long axis of the tooth.
• Searching for canals through an underprepared access cavity.
• Access through a small or flattened (disk-like) pulp chamber in a multirooted tooth.
• Access through a cast crown often is not aligned in the long axis of the tooth.
• Shifted or rotated tooth.
•

Prevention

• Clinical examination
• Thorough knowledge of tooth morphology and outlines of the access cavities .
• Identification of tooth angulation according to the adjacent teeth.
• Proper reading of the preoperative (diagnostic) radiograph to get information about the size and extent of the pulp chamber and internal changes (calcification or resorption).
• Radiograph from different angles (shifting technique).


Bur held alongside radiograph to estimate the depth
of penetration

• Operative procedures

• Access using “split technique” is preferred in specific cases.

2. Use of fiberoptic light and magnifiers
3. Removal of restorations when possible
•

Recognition

• Sudden pain
• Sudden hemorrhage
• Radiograph
• Apex locator
• Loss of apical resistance


Types and Treatment
• 1- Lateral root perforation
• A- Perforation at or above the height of crestal bone
• Treatment: restorative treatment
Supracrestal perforation repair

• B- Perforation below the height of crestal bone in the coronal third of the root

• The treatment goal is to position the defect above crestal bone by orthodontic extrusion or crown lengthening .

• Internal repair by mineral trioxide aggregate (MTA) is also possible .

• 2- Furcation perforation

Treatment: immediate sealing using the suitable restorative material (MTA)

Furcation repair using mineral trioxide aggregate (MTA)

Repair of stripping perforation (arrow)

Nonsurgical Treatment

• The site of the perforation must be found.
• The floor of the preparation cleansed.
• The bleeding stopped.
• Mineral trioxide aggregate (MTA) applied to the perforation .
• Because it takes MTA more than 3 hours to set, it should be covered with a fast-setting cement.
• The other canal orifices should be protected by placing paper points or an instrument in the canals to prevent blockage.

In the event MTA cannot be immediately applied,

• It is best to stop the bleeding,
• Place calcium hydroxide over the “wound,”
• Place a good temporary filling,
• Set an appointment with the patient, the sooner the better.
• The perforation area will be dry at the next appointment;
• MTA can be applied
• Treatment continued.

PROGNOSIS

• Factors affecting the long-term prognosis of teeth after perforation repair include:-
• The location of the defect in relation to crestal bone.
• The accessibility for repair.
• The size of the defect.
• The presence or absence of a periodontal communication to the defect.
• The time between perforation and repair.
• The sealing ability of restorative material.
• The technical skill of the dentist.
• The attitude and oral hygiene of the patient


Treatment of the Wrong Tooth
Treatment of the wrong tooth can be so easily prevented.

One should make sure through testing, examining, and radiography that one has confirmed which tooth requires treatment

Starting (not completing) the access cavity before applying the rubber dam

Damage to an Existing Restoration
Porcelain crowns are the most susceptible to chipping and fracture.

Also, do not place a rubber dam clamp on the gingiva of any porcelain or

porcelain-faced crown

Missed Canals

Additional canals in the:
• Mesial roots of maxillary molars MB2,3..
• The distal roots of mandibular molars.
• Second canals in lower incisors,
• Second canals in lower premolars,
• Third canals in upper premolars are also missed.
One must be prepare adequate occlusal access.

1- Ledge Formation

• Definition
• ledge has been created when the working length can not longer be negotiated and the original patency of the canal is lost.
•

Accidents During Cleaning and Shapaing

Causes
• inadequate straight-line access into the canal.
• inadequate irrigation or lubrication.
• excessive enlargement of a curved canal with files.
• packing debris in the apical portion of the canal.
• Starting with large file size
• Jumping to larger file before the smallest one become loose

Prevention

• Straight line access.
• Accurate working length measurement .
• Frequent recapitulation and irrigation.
• Use of lubricant like RC-PREP.
• Use of flexible Ni-Ti files in curved canals .
• Each file must be used until it is loose before a larger size is used .
• Avoid application of severe forces during instrumentation .


2-Root Perforations
• A- Apical perforation
• Types
1- Apical perforation through the apical foramen (over instrumentation)
It is caused by instrumentation of the canal beyond the apical constriction (incorrect working length)

• 2- Apical perforation through the body of the root in the apical third

•

Ledge apical perforation

• It is caused as a result of operator insistence to manage a ledge in the apical third (especially in curved canals)


Indicators
• Hemorrhage in the canal
• Bleeding at the tip of paper point
• Sudden pain
• Sudden loss of the apical stop
• Radiograph

Bleeding at the tip of paper point

• B- Stripping perforation
• Usually results from excessive flaring with files or drills.
• Over enlargement of canal
• Direction of lateral pressure distally (Gates Glidden)
Treatment:
• non-surgical treatment by immediate sealing using MTA
• surgical treatment: hemi-section, and root amputation
•




Indicators
They are similar to those of apical perforation
The area of hemorrhage on the point indicates the area where the strip has occurred.

Etiology

• Limited flexibility
• Multiple uses
• Excessive force applied to files
• Improper use, rotational movement when the apical part is engaged in dentin
• Uses of distorted instrument
• Notice: any instrument may break either steel, NiTi, hand or rotary
Separated Instruments

Recognition

• Removal of shortened file from the canal
• Loss of original working length
• Radiograph is essential for confirmation



• limitations of files is critical.
• Continual lubrication with either irrigating solution or lubricants is required EDTA paste.
• Each instrument is examined before use ( flutes distortion).
• Small files must be replaced often.
• To minimize binding, each file size is worked in the canal until it is very loose before the next file size is used.
• Nickel-titanium files usually do not show visual signs of fatigue similar they should be discarded according to the how many times were the instruments used.
• Prevention

Treatment

There are three approaches:

Attempt to remove the instrument using:

• Small file to bypass the instrument
• Removal by ultrasonic device
• Using especially designed pliers
for removal
Pliers

Instrument Aspiration or Ingestion

• Prevention
• Rubber dam uses
• Tighten the clamp and file with dental floss

Extrusion of Irrigant

Causes:
Wedging of a needle in the canal or out of a perforation
Prevention
• Loose placement of irrigation needles
• careful irrigation with light pressure
• use of a perforated needle prevent forcing the irrigating solution into the periradicular tissues
Signs and symptoms
• Sudden prolonged and sharp pain during irrigation
• Rapid diffuse swelling (sodium hypochlorite accident).

Severe swelling caused by injecting hydrogen peroxide irrigant into tissues.

A, Hemorrhagic reaction caused by NaOCl accident

B, Healing within few weeks
A B

Treatment

• Antibiotics in addition to analgesics for pain
• Antihistamines can also be helpful
• Ice packs applied initially to the area, followed by warm saline soaks the following day, should be initiated to reduce the swelling
• In more severe cases, hospitalization and surgical intervention with wound debridement, may be necessary
• Patient reassurance


Under filling
Causes
• Natural barrier (calcification) in the canal.
• Ledge.
• Insufficient flaring.
• Poorly adapted master cone.
• Error in W.L determination

Accident during obturation

• Prevention
• Confirmatory of master cone by radiograph
• Proper enlargement and fairing of canal
• Treatment
• Re-treatment
•

Overfilling

Causes
• Over instrumentation
• Open apex
• Uncontrolled condensation forces


Prevention
• Avoid over instrumentation.
• Prepare apical matrix (seat).
• Confirmatory MAC radiograph.
• If displacement of the MAC is suspected, a radiograph is made before excess gutta-percha removal.
• In case of wide (open) apex, a solvent customized cone technique is preferred .