Endodontic Surgery and Root Canal Procedures

Steps in Root End Surgery

• Local anesthesia and hemostasis
• Management of soft tissue
• Management of hard tissue
• Surgical access (visual and operative)
• Access to root structure
• Periradicular curettage
• Root end resection
• Root end preparation
• Root end filling
• Soft tissue repositioning and suturing
• Post-surgical care

Root End Preparation

Preparing a cavity to receive root end filling.

According to Carr and Bentkover, this involves a Class I preparation at least 3mm into root dentin with walls parallel to and coincident with the anatomic outline of the pulp space.

Key requirements:

1. The apical 3mm of the root canal must be freshly cleaned and shaped.
2. The preparation must be parallel to and coincident with the anatomic outline of the pulp space.
3. Adequate retention form must be created.
4. All isthmus tissue, when present, must be removed.
5. Remaining dentin walls must not be weakened.

Ultrasonic Root End Preparation

Utilizes ultrasonic chisels or scaling tips (Bertrand and colleagues) to remove bone and root apices.

Advantages of Ultrasonic Preparation:

• Smaller preparation size
• Less need for root end beveling
• Deeper preparation

Root End Filling

The material used should:

• Prevent leakage of bacteria and their by-products into periradicular tissues
• Be non-toxic
• Be non-carcinogenic
• Be biocompatible
• Be insoluble in tissue fluids
• Be dimensionally stable
• Be unaffected by moisture during setting
• Be easy to use
• Be radio-opaque

Additionally, it should not stain tissue.

Root End Filling Materials

• Gutta-percha
• Amalgam
• Cavit
• IRM (Intermediate Restorative Material)
• Super EBA (Ethoxybenzoic Acid)
• Glass ionomer
• Composite resins
• Carboxylate cements
• Zinc phosphate
• Zinc oxide eugenol cement
• MTA (Mineral Trioxide Aggregate)

Endodontic Etiology

Predisposing Factors:

• Root anatomy
• Amount of remaining sound tooth structure
• Loss of moisture in the dentin
• Amount of bony support
• Pre-existing cracks

Iatrogenic Factors:

• Tooth structure loss
• Use of needles during irrigation
• Stress generated during procedures, such as lateral condensation of gutta-percha
• Restorative procedures
• Post placement

Chronic Apical Abscess

Diagnosis:

Collection of pus resulting from a carious lesion or injury causing pulp necrosis.

Clinical Examination:

Characterized by gradual onset with little or no discomfort and an intermittent discharge of pus through an associated sinus tract.

Pulp Tests:

Show no response.

Periapical Tests:

Not tender to percussion and palpation.

Radiographically:

Typically shows signs of osseous destruction, such as a periapical radiolucency.

Endodontic File Modifications

Material:

NiTi (Nickel Titanium)

Modification in Cross Section:

• K-Flex: Rhomboidal cross section, twisted like a K-file. Increases flexibility and cutting effect, improves debris clearance (obtuse angle).
• Flexo-O-File: Triangular cross section. Increases flexibility and cutting effect.
• Flex R: Machined K-file with a triangular cross section. Increases cutting effect.
• Unifile: H-file with a double helix S shape.

Modification in Tip Design:

• K-Flex: Untwisted tip.
• Flex R: Round tip.

Modification in Taper:

• Standard taper: 0.02
• Other systems (e.g., ProTaper, etc. - assuming 'Oho system' is a typo or specific system not fully named): 0.04, 0.06, 0.10, 0.12