Classification of filling materials for root canals.
On physical and mechanical properties of material for filling root canals can be divided into 3 groups (Strelyukhina T.F., 1964):
I. Plastic non-hardening:
sea buckthorn, thymol, lysozyme containing calcitonin containing, iodoform, etc.
II. Plastic hardening materials.
III. Solid filling materials (pins):
- Gutta-percha;
- Plastic;
- Copper;
- Silver.
Borovsky E.V. (2004) classifies the filling materials for root canal:
1. Temporary filling materials,
2. Paste (sealant, sillers),
3. Solid filling materials (fillers).
Classification of materials for permanent filling of root canals (Borovsky E.V., 2004):
Hardening paste sillers
1.1 Simple.
1.1.1. Zinc-oxide eugenol (zinc-oxide eugenol paste).
1.1.2. Polymer.
1.1.2.1. Synthetic ("AN-26", "AN PLUS Dentsply, Diaket ESPE).
1.1.2.2. Natural (hloropercha).
1.2. With therapeutic effect.
1.2.2. Zinc-oxide eugenol-based (Endospad, Pulpispad Dentsply, Endometasone Septodont)
1.2.2. Polymer-based (Sealapex, Kerr).
Primary solid fillers
2.1. Plastic (gutta-percha pins).
2.2. Hard (silver pins).
2.3. Combined (Thermafil, Dentsplay).
Modern materials for obturation canals can be represented by the following indicators:
I. Physical and chemical criteria.
II. Fillers, sealers.
III. On the target application:
a) Temporary filling (endokal, biokaleks, endometazon N, etc.);
b) Permanent filling.
IV. According to the form of:
- Liquid-powder;
- Paste-paste;
- Pasta, ready to use;
- Capsule form.
Requirements for filling materials for root canal:
Requirements for filling materials are varied and can be divided depending on the biological and physical characteristics as well as the practical problems:
1. biological:
- Be non-toxic and have good biocompatibility
- Do not irritate the periodontal
- To stimulate the function of periodontal plastic.
- Bacteriostatic effect or not to support the growth of bacteria.
- Easily sterilized before use.
- Not to have mutagenic and carcinogenic properties
2. physical:
- To ensure a reliable seal the root canal system throughout its entire length, repeating features of its structure.
- To maintain constant volume (not shrink in the canal)
- Preferably a slight increase in volume when administered in feed or in the process of curing.
- Not to be porous
- Have enough for a comfortable work curing time.
- Good adhesion to dentin and filling materials.
- To be water resistant
- Do not dissolve in the interstitial fluid
3. practical:
- Easy entry into the canal
- To be radiopaque
- Do not paint a tooth
- Easily removed from the canal.
Temporary filling materials are using to close the root canals with different non hardening pastes. They can be administered for a period of 1 day to several months. These substances have different therapeutic effect and must be replaced at regular filling materials.
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Permanent filling materials used in the final stage of the root canal treatment. The purpose of this procedure can be considered as a maximum and tight space filling root system after its chemical and mechanical processes. Unfortunately, none of the material that meets all these requirements simultaneously, currently does not exist. To achieve this goal using different combinations of permanent filling materials, this can be divided into two large groups: hardening and pervichnotverdye. Non hardening filling materials for permanent fillings do not apply.
The quality of the endodontic obturation is usually evaluated using radiographic images upon completion. Additionally, during the root canal preparation and obturation phases of treatment, clinical criteria can be identified that are essential for achieving an adequate root canal obturation. Prior to the obturation phase, the clinician must establish the proper shape and size of the root canal. Proper canal preparation provides an apical resistance form for the adequate adaptation of filling materials and the prevention of excessive apical extrusion of these materials.
Remember, what is removed from the root canal during cleaning, shaping and disinfection is more important than what is placed during obturation. Biomechanical preparation and disinfection are achieved through mechanical instrumentation and copious irrigation to remove bacterial and tissue debris, and by shaping the root canal space to allow for a three-dimensional obturation and seal of the root canal system. The importance of maintaining the original shape of a root canal during and after cleaning and shaping in order to promote periapical healing in endodontic cases has been demonstrated in several studies. The clinicians inability to maintain the original shape and to develop the proper taper of canals can result in procedural errors such as ledges and perforations.
When preparing root canals for obturation the clinician must maintain the working length during the instrumentation phase of treatment.
Maintaining working length is essential for preparing and sealing the root canal to its proper apical extent. It is also necessary to create an apical resistance form to obtain adequate compaction of the filling materials and also to prevent excessive overextension of materials into the periapical tissues. Todays clinicians have a number of methods, materials and technologically advanced instruments at their disposal to achieve these goals. Examples of these are electronic apex locators, nickel-titanium rotary instruments, various irrigation systems, newly formulated sealers, and microscopic magnification and illumination. Poor obturation quality as judged by radiographs has been associated with non healing in 65 % of retreatment cases.
Obturation errors often are a result of inadequate cleaning and shaping (ledges, perforations, inaccurate working lengths, and underprepared or overprepared canals). If inadequate obturation is not a result of an instrumentation error, the clinician should recognize this reversible procedural error on the obturation check film. The obturation material should then be removed and the canal re-obturated prior to restoration. If the procedural error is gross overextension of material into the periapical tissues, removal by conventional means may not be possible and periapical surgery may be necessary.
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Many good techniques are available to the clinician for the instrumentation phase of root canal treatment. Smooth, clean, and properly shaped and sized canals will allow for efficient removal of debris with instruments and irrigants, and insertion of sealers and placement of root filling material. If a clinician is having difficulty with the obturation phase of endodontic therapy, their cleaning and shaping technique should be reevaluated prior to consideration of changing obturation techniques.
Microorganisms and their byproducts are the major cause of pulpal and periapical disease. However, it is difficult to consistently and totally disinfect root canal systems. Therefore, the goal of three-dimensional obturation is to provide an impermeable fluid tight seal within the entire root canal system, to prevent oral and apical microleakage.
Preparation of dentin surface (irrigation)
The purpose of endodontic irrigation is to remove debris created during instrumentation, and to dissolve and/or flush out inorganic and organic remnants of the pulp system, bacteria and bacterial byproducts that are not removed by mechanical instrumentation. With the introduction of obturation materials designed to bond with dentin, irrigation solutions must be used with consideration of the condition of the dentin surface that is most suitable for bonding.
Modern root canal treatment requires the use of both mechanical and chemical preparation and disinfection of the canal system. During cleaning and shaping procedures, a superficial amorphous layer of tissue remnants, organic and inorganic materials, and bacteria and their byproducts accumulate on the canal walls. This smear layer may interfere or prevent adhesion of sealers to the canal wall and serve as a substrate for bacterial growth. Evidence tends to support removing the smear layer prior to obturation. This removal supports reduction of potential irritants and permits better adaptation of sealer to the canal walls. Removal of the smear layer is easily accomplished by irrigating the canal with 17% disodium EDTA for one minute, followed by a final rinse of sodium hypochlorite. Chelators remove the inorganic components and sodium hypochlorite is necessary for removal of the remaining organic components. Adequate irrigation of root canals requires an effective irrigant as well as an efficient delivery system.
The irrigating system should be one that does not allow the irrigant to extrude
beyond the apical foramen into the periapical tissues.
Characteristics of an ideal irrigation system
Physical flushing of debris
Biocompatible
Bactericidal agent
Sustained effect
Disinfect and detoxify dentin and tubules of all microbial substances
Tissue solvent
Lubricant
Smear layer removal
Not affect physical properties of dentin
