Medication (washing) of root canals
Topic 32: “Amputation, extirpation of the pulp, removing its necrosis: instruments, the sequence features of each manipulation, complications. Drug treatment of root canals: instruments, medicines. Errors and complications”.
Coronal pulp is the part of the dental pulp contained in the crown portion of the pulp cavity.
Amputation of the pulp (pulptomy)– is operation that mean cutting of coronal pulp. Removing of the coronal pulp with sharp excavator. In this case, amputation wound has a linear form, and creates favorable conditions for its healing.
Indications for amputation of the pulp:
1. Acute local pulpitis;
2. Traumatic pulpitis;
3. Chronic fibrous pulpitis;
4. Chronic hypertrophic pulpitis;
5. General acute pulpitis with mild percussion reaction and not older than one day.
This method recommended in multi-rooted teeth with a clear transition of border between the coronal and root pulp, young persons to 40 years old, in the absence of severe systemic diseases, without periodontal disease.
Extirpation of the pulp (pulpectomy) -completes removal of the coronal and root pulp. Pulpectomy completed in apical root section before reaching the apical foramen 1-1.5 mm, to prevent injury to the periodontium, with help of the endometrs, the presence of X-rays – with help of rulers. In the remainder of the pulp stump after decrease reactive inflammatory response is healing.
Indications for extirpation of the pulp:
1. All the total forms of pulpitis;
2. Residual pulpitis.
3. The presence of stones in the pulp.
4. Retrograde pulpitis.
5. Pulpitis patients with periodontitis of moderate and severe.
6. All forms of pulpitis in patients with common diseases (diabetes, atherosclerosis).
Root pulp can be removed in two ways:
1. After amputation of coronal pulp immediately injected pulp extractor to the way of the root canal, turn it 1-2 turns and extract the root pulp;
2. After amputation coagulate root pulp. Then, to pipe and extract with pulp extractor coagulated pulp.
However, the aims and tasks of the biomechanical treatment always remain the same:
1. Removed from the canal pulp tissue or decay;
2. Remove a layer of infected dentin, located on the walls of the canal;
3. Produce pharmacological processing of canal;
4. Give the canal a conical shape, suitable for sealing.
Errors and complications in amputation and extirpation:
1. Perforations in the bottom of the tooth cavity or wall;
2. In the 1-2 day appears spontaneous pain or pain from thermal irritants;
3. Break off instrument in the canal;
4. Bleeding after amputation and extirpation.
Medication (washing) of root canals
When preparing a root canal it is compulsory to apply thick and liquid washing solutions. This procedure is an important part of treating the canal since it is aimed at denaturation and removal of the remnants of tissues or bacteria. The medicines, used for treating root canals, must comply with specific requirements:
- to have bactericidal action on microorganisms associations;
- not to irritate pre-apical tissues;
- not to have sensibilizing action on the body;
- have fast action and deep penetration into dentine tubules;
- be chemically stable and remain active after long storage period.
Medicines are used for disinfecting the areas, which cannot be treated with endodontic instruments due to their complex anatomy. Washing solutions may also function as lubricants between the instrument and the root walls. Therefore, the instrument can easier overcome the resistance in narrow and strongly curved places.
Antiseptic washing solutions regardless of their composition are able to wash away the removed tissues from the root canal, which prevents its occlusion. Chemical effect of the washing solution is achieved only by complete irrigation of the canal walls. However, none of the existing washing solutions for root canals has sufficient surface tension to achieve maximum effect. At present two ways of canals medication (washing) are applied: 1) with cotton turundas or paper posts, wetted with antiseptic solution; 2) with a syringe. The second way has appeared to be the most efficient one.
The canal is washed with a syringe through a special endodontic needle. The needle has a blunt end and lateral openings not to let the liquid, fed under pressure, get onto the pre-apical area, but make it come out to the wider parts of the canal and continue its action.
The needle point should be placed 3-5mm from the root apical opening as it reduces the risk of spraying the solution beyond the apex. Before introducing the needle into the canal, it may be bent under the desirable angle. The antiseptic solution is introduced in the canal under low pressure. To wash one root canal during endodontic treatment it is necessary to have 10-15 ml of antiseptic solution. Using a thin endodontic needle the risk of excessive pressure on the pre-apical tissues is higher than when thicker needles are applied.
The essential aim of the mechanical treatment is to properly shape each canal so that it can be filled with the filling material.
Recent research has showed that not more than 70% of root canal walls were treated with high quality. This treatment was mostly performed in the areas of contact with a instrument. The major part of micro-canals, including narrow, twisted and non-round ones, remains untreated.
The approach to selecting antiseptics, used in endodontics has lately shifted to the medicines which are sparing, adequately borne by tissues and tolerant to periodontium. Under their pharmacological action they refer to different groups of drugs. Among non-specific antiseptics most often are used those medicines, which contain chlorine and iodine, nitrofurans, hydrogen peroxide, quaternary ammonium compounds, proteolytic enzymes etc.
Hydrogen peroxide (oxidant). In the endodontic practice hydrogen peroxide is used in the form of 3% solution solely as washing liquid. Contacting living tissue or organic substances, hydrogen peroxide instantaneously dissociates into molecular oxygen and water. Quick release of gas bubbles, which have weak bactericidal action, assists in mechanical cleaning the canal from necrotized tissues and dentine particles. It should be noticed that hydrogen peroxide is incapable of dissolving necrotized tissues and other organic remnants.
Chlorinated medicines. Among these medicines are 2% solution of chloramine B and 3-5% solution of hypochlorite, 0,1-1,0% solution of chlorhexidine, chloramine T. Manifested bactericidal action of these medicines is connected with the release of chorine gas that penetrates into the dentine tubules and disinfects their content. It is known that when chloramine contacts with tissues around 13% chorine and oxygen are segrerated. It is thought that low toxicity of chloramine after segrerating chlorine and oxygen is connected with turning chloramine into a low-active compound –sulfamide parabenzole.
Another well-known chlorinated medicine is chloramine T (134,4 g chloramine, 26 g sodium chloride and 3,3 ml water). Chlorine is slowly released from this compound, which relieves its irritating action. Bactericidal action of chloramine T, as well as of sodium hypochlorite, is connected with the formation of hypochlorous acid and chlorine gas. The solution of chlorhexidine bigluconate has antiseptic, bactericidal and fungicidal action. To treat root canals 0,5-1,0% water solutions are used.
Among the chlorinated medicines that are widely used abroad, and at present in our country too, is 3-5 % solution of sodium hypochlorite, containing about 1% chlorine. This solution has been used for treating root canals for over four decades.
Sodium hypochlorite is highly effective solvent of necrotized tissue. It dissolves 7 times more organic tissue than citric acid.
It has been found out that the sodium hypochlorite solution may dissolve predentin. It is important since most bacteria are in predentin and adjacent dentine.
The ability to dissolve necrotized tissue is a vital property for chemical drug solutions that are used in the endodontic practice.
Raising the temperature of the sodium hypochlorite solution from room temperature to the body temperature (37˚C) considerably intensifies its antimicrobic and lysing action. The use of this medicine alongside with ultrasound also significantly intensifies its antimicrobic action and sodium hypochlorite lysing properties.
It is recommended to use 3% solution of hydrogen peroxide and 5,25 % solution of sodium hypochlorite during chemical and mechanical tooth root canal treatment. Some advantages of combined usage of H2O2 and NaOCl have been singled out: foam formation and oxygen release. The foam formation is highly efficient when shifting large conglomerates of necrotic mass in the tooth root canal.
The oxygen, released in the result of chemical reaction, is an efficient agent in destroying some stable anaerobes.
Iodinated medicines. Iodinolum is a complex compound of iodine and synthetic polymer - polyvinyl alcohol. The medicine has intensive bactericidal and fungicidal action, normalizes regeneration of tissues and stimulation of phagocytic activity of leukocytes. In endodontics 1% iodinolum solution is used to treat root canals. Iodinolum functions as an indicator: contacting with the environments that contain tissue decay products, microorganisms and purulent discharge, it loses its initial (deep-blue) colour. Providing thorough treatment of the canal with iodinolum, the iodinolum wetted turunda stops losing its deep-blue colour.
Iodoatum is a water solution of the complex of surface-active substance and iodine. It contains about 4,5% iodine; has bactericidal and fungicidal properties.
Betadine (polyvidon-iodine) is a medicine, whose essential component is active iodine in the form of polyvinyl-pyroliden-iodine. It is used as 1% solution. Polyvinyl-pyroliden-iodine belongs to iodophors, binding iodine. Contacting with tissues, iodine is gradually and evenly released, preserving non-selected bactericidal action.
Nitrofuran medicines. Furacillin, furasoline, furazolidone and furagin are successfully applied to treat root canals. These medicines have a wide range of antibacterial action to gram-positive and gram-negative bacteria, as well as to the microorganism strains that are resistant to other medicines. It is recommended to use 5 % solution of furacillin, 0,1-0,15% solution of furasoline, furagin and furazolidone.
Quaternary ammonium compounds. These are cation detergents or wetting substances that have intensive bactericidal and bacteriostatic action on nonspore-forming germs, yeast fungus and weak irritating action on the living tissues. In the alkaline medium they are more effective, than in the acidic one. Water solutions of these compounds are stable, colourless, nearly odourless, have low surface tension and are effective in contacting with organic substances. Good results have been received with the use of 0,1% solution of decaminum and 0,15% solution of decametoxinum. Abroad, for medical treatment of infected canals the following medicines of this group are used: benzalkonium cloride (zefiran cloride) – 1% solution and cetylpyridinium chloride (biocept) - 1% solution.
Proteolytic enzymes. These enzymes were first used in the 30-40s of the twentieth century to dissolve necrotized tissues. Enzyme-therapy is based on the selective action of proteolytic enzymes on necrotic tissues. Proteolytic enzymes promote dilution of thick secretion fluid in the root canal and quick removal of the devitalized tissue from it, not affecting the living tissue. Theoretically these enzymes must dissolve the pulp remnants. Endodontic practice has applied streptokinase, streptodornase, papain, enzimol, purified tripsin etc.
Tripsin is able to split necrotized tissues and fibrin formations, dilute thick secret fluid, exudates, remains active in the environment with pH 5,0-8,0. It is used individually as 0,2% solution as well as in combination with antibiotics and sulfanilamides. Isotonic solution of sodium chloride is used as a solvent. Crystal chymotripsin is a proteolytic enzyme, differing from tripsin in splitting mostly the links, formed by the remnants of amino acids. This enzyme is more stable than tripsin; it inactivates more slowly. The medicine is soluble in water and isotonic solution. The indications to its use are similar to those of tripsin. As an enzyme medicine natural gastric juice may be used as it has the whole range of enzymes.
Surface-active substance group. Dimexidum (Dimethyl sulfoxide) has been used in dentistry. The medicine is not toxic, has intensive anti-inflammatory action. It is effective against coccal microflora, easily penetrates through undamaged biological membranes and is a conductor for other medical substances. Dimexidum is used as 20% water solution.
Before filling it is recommended to wash the canal with distilled water to remove the remnants of any antiseptic solution and dry it with paper posts.