Essay 48 - obturation of the root canal system - prerequisites for filling of root canals, goals. root canal filling materials - requirements, types, classification

what is obturation of root canal system? define

• the three dimensional filling and sealing of the cleaned, shaped and disinfected endodontic space using appropriate filling materials. its purpose is to completely and permanently seal all the pathways between the root canal system and the surrounding periapical tissues, thereby preventing the entry or entrapment of microorganisms and tissue fluids, and promoting the healing of periapical tissues.

• Anachoresis is the phenomenon where microorganisms (bacteria) that are circulating in the bloodstream are able to localise and settle in areas of inflammation or injury within the body, including inside a non exposed inflamed dentin pulp

what is Anachoresis?

• is the phenomenon where microorganisms (bacteria) that are circulating in the bloodstream are able to localise and settle in areas of inflammation or injury within the body, including inside a non exposed inflamed dentin pulp

prerequisites for filling of root canals

• before obturation (filling), the following conditions must be fulfilled;

1. the endodontic space must be completely cleaned, shaped and disinfected

2. no empty spaces should remain in the root canal

3. the root canal system must be dry and free of infection before obturation

4. proper chemo-mechanical preparation must be completed

5. biological rationale: even if sterilisation is almost impossible, obturation prevents bacteria that survived cleaning from multiplying

6. sealing off the endodontium from the periodontium is essential to prevent reinfection or inflammatory reactions

the goals of obturation

• hermetic (fluid- tight) seal: prevent entry and entrapment of bacteria and tissue fluids. block “ portals of exit” (e.g apical foramen, lateral canals)

• entrapment of residual micro organisms: immobilise and entomb any remaining microorganisms, preventing their growth

• three dimensional sealing of entire endodontic space

• prevention of reinfection: stop future contamination from the oral cavity or periapical tissues

• promotion of healing: allow periapical tissues to heal by removing sources of irritation

• Support to the root: strengthen and support the remaining teeth structure internally

requirements of ideal root canal filling materials

1. Biological

• Non‑irritating to periapical tissues

• Bacteriostatic or does not support bacterial growth

• Non‑resorbable

• Does not discolor tooth structure

• Sterile or easily sterilized

2. Physical

• Adapts well to canal walls

• Provides a tight apical and lateral seal

• Dimensionally stable (no shrinkage; slight expansion acceptable)

• Impervious to moisture

• Radiopaque

• Poor conductor of heat

3. Handling

• Easy to mix, insert, and manipulate

• Semi‑solid/flowable during placement, solid after setting

• Sets in a reasonable working time

• Adheres to canal walls

• Easily removable for retreatment

types of root canal filling materials

• non setting pastes (stay soft inside canal; do not harden up insertion)

• setting pastes (cement and sealers) (self hardening materials that become solid after setting)

• solid materials(rigid elements like silver cones - now obsolete)

• semi solid materials (materials like gutta-percha that are pliable when heated)

List the classifications of Root Canal filling materials

1. non setting pastes

2. setting pastes (cements and sealers)

3. solid materials

4. semi solid materials

describe non setting pastes

• used to fill canals but do not harden

• historically based on antiseptic and therapeutic principles

• now considered outdated with a poor long term success and resorption

describe Setting pastes (cements and sealers)

• cement sealers: self hardening cements used with a solid or semi solid material

• cements: self hardening materials used alone to fill the entire canal

describe solid materials

• silver cones: Historically Used, now obsolete

1. no adaption to canal walls

2. corrosion over time (formation of cytotoxic products)

3. poor sealing capability in irregular canals

describe semi solid materials

• Gutta-Percha: the current gold standard

1. thermoplastic properties ( can be compacted when heated)

2. stable after setting, minimally resorbabale

3. excellent tissue tolerance

4. radiopaque

5. slight antibacterial activity (mainly due to zinc oxide content)

6. needs a sealer to compensate for the lack of chemical adhesion to dentin