INTRA CANAL MEDICAMENTS: INTRODUCTION: The ultimate Aim of Root Canal therapy is to eliminate pathogenic microorganisms so as to achieve ideal healing. The main modalities to accomplish this are through biomechanical preparations and intra canal medication. Through the ages various chemicals have been experimented with to achieve the ideal root canal sterilant ranging from phenols to calcium hydroxide. Let us explore this fascinating group of compounds and understand how they work, so as to achieve the optimal result.
HISTORY: The historical origins of intra canal medicaments date back to very early times Seribonius in 1045 AD wrote of using oils and wine in the mouth of a patient in pain. This was a crude attempt to achieve a topical anesthetic effect on a tooth to be extracted. Dental writings through the middle ages indicate the use of oil of cloves, a plant extract containing a high percentage of eugenol. In 1800 specific medicaments were recommended for endodontic treatment
Beach wool creosate was mentioned in 1840 article creosate and cotton in canal filling, this medicaments is still in common use today. In 1884 Richmond advocated “ knocking out the pulp” by whittling down orangewood to a small size, soaking the stick in phenol & tapping this into exposed pulp canal. Phenol was added to preserve and sterilize the contents of canal and to alleviate pain
IDEAL REQUIREMENTS: It should be an effective germicide and fungicide It should be non-irritating to the periapical tissues. It should remain stable in solution It should have prolonged antimicrobial effect It should be active in the presence of blood serum and protein derivatives of tissues It should have low surface tension It should not interface with repair of periapical tissues. It should not stain tooth structure It should not induce cell mediated immune response It should be capable of inactivation in a culture medium
CLASSIFICATIONS: ACCORDING TO DCNA: 1) Phenolics Engenol Comphorated Monopara Chlorophenol (CMCP) Parachloro phenol (PCP) Comphorated Parachloro Phenol (CPC) Meta cresylacetate (Cresatin) Cresol Creosote (Beechwood) Thymol 2) Aldehydes Formo cresol Glutaraldehyde 3) Halides Sodium hypochlorite Iodine – potassium todide 4) Steroids 5) Calcium hydroxide 6) Antibiotics
7) Combinations ACCORDING TO GROSSMAN: 1) Essential oils- Eugenol 2) Phenolic Compounds -Phenol -Para Chlorophenol -Camphorated Para Chlorophenol - Formocresol -Glutaraldehyde -Cresatin 3) Halogens -Na Hypochlorite -Iodides 4) Quaternary Ammonium Compounds -9 – amino acridine
ACCORDING TO INGLE: Ingle classified antimicrobial agents broadly into 2 groups Conventional antiseptics / Locally used antiseptics Chemotherapentics
Locally used antiseptics – Includes 1) Alcohols
Ethylalcohol Isopropyl Alcohol
2) Phenolic Compounds Phenol Camphorated Phenol Paramono chlorophenol Thymol Eugenol Creosote 3) Heavy Metal Salts: Salts of Silver, Mercury, Copper 4) Cationic Detergents: Quaternary ammonium compounds. 5) Halogens: - Na hypochlorite - Potassium iodide, iodine MODE OF ACTION: Conventional antimicrobials attack cells in various ways. When used in high concentration they have a destructive effect on the bacteria as to cause denaturation of cell proteins. Antimicrobial agents such as phenols, thymol,
Creosate, Eugenol cause coagulation of proteins and subsequently loss of cell metabolic function may result. Detergents act as germicides by modifying and damaging the physical and chemical properties of the bacterial cell membrane, Iodine, Chlorine and heavy metals are strong enzyme inhibitors and therefore have a destructive effect on microbial cells. The catalytic effect of enzymes is caused by their affinity to natural substrate. A competitor if any chemical compound similar to the substrate that can combine with the active enzyme center but cannot be metabolized through such chemical antagonism the competitor remains attached to the enzyme and thus prevents it from being active with the natural substrate sulfonamides function as competitor and thus act as antiseptics. INDIVIDUAL INTRA CANAL MEDICAMENTS: PHENOL Also called carbolic acid It is the oldest compound for controlling microorganisms. It was introduced by lord Lister in 1867 It is white crystalline substance, and has a characteristic odour derived from coal tar Phenol is a protoplasm poison and produces necrosis of soft tissues by its ability to penetrate and disrupt the cell wall of bacteria and subsequently the protoplasm. Liquefied phenol consists of a parts of phenol and 1 part water This substance is highly effective in as low concentration as 1% to 2%
CAMPHORATED PHENOL This contains 30% Phenol, 60% Camphor, 10% Ethyl alcohol It is the least toxic of the phenolic compounds It has excellent antimicrobial effect and also relives pain Camphorating process aims at developing a less caustic medicament as a result of the slow release of phenol, camphor serves as a vehicle and diluent. In clinical use the phenolic compounds are relatively ineffective as antiseptics.
MONOCHLOROPHENOL (MCP) It is a derivative of phenol and has three isomers of which paramonochlorophenol is the most effective. Mono chlorophenol is more effective antiseptic and is also more toxic than phenol. CAMPHORATED PARAMONO CHLOROPHENOL (CMPCP) (Developed by walkhoff 1891)
Contains 35% Monochlorophenol
65% Camphor
Its antimicrobial effect is good But it is highly toxic to the tissues It is used in the form of vapour forming intracanal medicaments. The vapors can pass through the apical foramen. FORMOCRESOL Developed by Buckley in 1906 Contents – 19% formaldehyde
35% Cresol
46% H2O and glycerin.
Or is a combination of formalin and cresol in the proportion of 1: 2 Formocresol combines the protein coagulating effect of phenolic compounds with the alkylating effect of formaldehyde. The bactericidal effect of formocresol is good at levels as low as 2% It is a strong poison and causes widespread destruction of living tissue followed by a persistent inflammatory reaction Its vapor forming effect is also good Studies have reported that formocresol treated tissue produced a cell mediated immune response. The formaldehyde in contact with tissue in the pulp and periapical tissues is transported to all parts of the body considering the outright
toxic and t issue destructive effects and the mutagenic and carcinogenic potential, there is no clinical reason to use formocresol as an antimicrobial agent for reason to use formocresol as an antimicrobial agent for endodontic treatment. The alternatives are better with significantly lower toxicity
GLUTARALDEHYDE It is a colorless oil, slightly soluble in H2O
Slightly acidic It is strong disinfectant and fixative Used in concentration of 2% as ICM Extent of toxicity is less compared to formaldehyde. Its molecular weight is high compared to formaldehyde hence does not penetrate in to the periapical tissue
CRESATIN Also known as metacresylcetate It is a clear, stable ,oily liquid of low volatility It has both antiseptic and obtundant properties Compared to formocresol or camphorated parachlorophenol the antimicrobial effect of cresatin is less. Its effect on tissue ranges from mild to severe
CREOSOTE It is a mixture of phenol and phenol derivatives Beachwood creosote has long been used in endodontic therapy There are several reports on severe tissue irritation and necrosis.
ALCOHOL: Ethyl alcohol and isopropyl alcohol are used. These denature proteins in high concentration Denaturing takes place in presence of water, hence 70% is preferred to 95% They are not recommended as intracanal medicaments.
EUGENOL It is the chemical essence of oil of clove It is related to phenol It is both an antiseptic and an obtundant It is slightly more irritating than oil of clove Studies have reported that eugenol inhibited intradental nerve impulses. A few reports of allergy to eugenol have been reported.
HEAVY METAL SALTS Salts of silver, copper and mercury are used as ICM They coagulate proteins and act as enzyme inhibitors. They are toxic They mercury salts are rendered less effective by the tissue fluid proteins present in the root canal. Hence they are not often used. N2 Introduced by Sargenti. Contains: Paraformaldehyde Phenylmercuric borate Eugenol, Additional ingredients like lead, corticosteroids, Antibiotics It is claimed to be both ICM and a sealer N2 has a permanent disinfectant action and unusual antimicrobial properties, have been denied by the council on dental therapeutics of the American Dental association The antibacterial effect of N2 is short-lived about- a week to days. HALOGENS Includes chlorine and iodine containing compounds. sodium hypochlorite: Hypochlorite was first used by semmelweis in 1847 as a hand disinfectant. This initial use of potassium hypochlorite was substituted by sodium hypochlorite by Carrel and Dakin for wound disinfection.
ďƒ˜ Mechanism of action: When hypochlorite contacts tissue proteins, nitrogen, formaldehyde and acetaldehyde are formed. The peptide links are broken up and this dissolves the proteins. During the process hydrogen in the amino groups (-HN-) is replaced by chlorine (-NCL-) there by forming chloramines, which plays an important role in antimicrobial effectiveness. Thus necrotic tissue and pus are dissolved and the antimicrobial agent can better reach and clean the infected areas. Temperature significantly improves the antimicrobial effect of sodium hypochloride Dakin suggested a 0.5% solution (Dakin’s solution)- at this concentration toxicity is low and it affects only necrotic tissue. A 1% sodium hypochlorite solution however is more potent and provides an increased antimicrobial effect. Higher concentration of NaOcl (2.5% and 5%) attack living tissue without contributing significantly to treatment (i.e, in antibiotic activity) Bystrom and Sundquist have demonstrated that the rate of root canal dissinfection was similar regardless of whether 0.5% or 5% concentration of NaOcl was used. The activity of NAOCL is intense but of short duration. Hence the compound should preferable be applied to the root canal every other day.
IODIDES Iodine has been used for many years and is known for its mild effect on living tissue. Iodine is highly reactive, combining with proteins in a loosely bound manner so its penetration is not impeded. Iodine potassium iodide which contains 2% I 2, 4% KI and 94% distilled water has excellent antimicrobial activity and minimal toxicity and tissue irritating qualities.
CATIONIC DETERGENTS: The quaternary ammonium compounds have low surface tension and good cleansing effect. The antimicrobial effect of these compounds are not strong Mechanism of action is as follows: the “Quats” are positively charged and the microorganisms are negatively charged thus a surface active effect in which the compound clings to the microorganism and reverses the charge. These compounds may delay wound heating These compounds are used in the concentrations between 0.1% to 1% for root canal irrigation, but rarely as intracanal dressings. Salvirol is also a detergent suggested for irrigation during root canal instrumentation. It has chelating effect. Salvizol causes some degree of tissue irritation.
CALCIUM HYDROXIDE Herman introduced Ca (OH)2 paste as an ICM in 1920. Calcium hydroxide paste for intra canal use is a thick suspension of Ca(OH)2 powder in sterile water or saline The high PH of calcium hydroxide paste is responsible for the destructive effect on bacterial cell membrane and protein structured Few bacteria can survive at this PH of approximately 12.5 In addition to its antimicrobial qualities the paste may also aid directly or indirectly in the dissolution of necrotic pulp tissue. Tissue submerged in Ca(OH)2 for a day is more easily dissolved with NaOcl than is untreated tissue Bystrom etal showed that Ca(OH)2 paste effectively eliminated all microrganisms in infected root canal, when the dressing was maintained for 4 weeks. ANTIBIOTICS & STEROIDS Alone and in combination with other drugs, antibiotics are indicated in a small minority of cases when root canal infection persists despite other antiseptics Ledermix paste or polyantibiotic paste (PBSC) are used
LEDERMIX PASTE: Contains: 1% triamcinelone acetonide 3% dimethylchlortetracycline PBSC PASTE: Contains: Potassium G (10,00,000 units), Bacitracin(10,000 units) Streptomycin sulphate & sodium caprylate.
FREQUENCY OF MEDICATION: According to the general principle of root canal management, disinfectant dressings should preferably be renewed in a week and not longer than 2 weeks because dressings become diluted by periapical exudates and are decomposed by interaction with the microorganisms. The mode of application traditionally was a short blunt absorbent point moistened with the medicament is placed in to the canal, a cotton pledget From which excess medicaments has been expressed is placed in the pulp chamber and the access cavity is sealed. In narrow canals a dry absorbent point is inserted and a cotton pledget moistened with the medicaments is
placed against the absorbent point to moisten it. A dry cotton pledget is used to absorb the excess medicament and the cavity is sealed. However many endodontists prefer to place a medicated cotton pellet in the chamber from which excess medicament has been removed. They depend on the vaporization of the medicament in the pulp chamber for antibacterial action. They do not place an absorbent point in the root canal. Is then sealed with a temporary restorative material
ANTIMICROBIAL EFFECTIVENESS: The effectiveness of antimicrobials depends upon the direct contact of the agent with the virus, bacteria or fungus and in sufficient concentration. There is a serious draw back to the use of a chemical substance in a pulp space, that substance probably does not reach all areas where bacteria are sequestered. Another significant concern is the duration of effectiveness of the medicaments in the pulp space recent research has shown that the antibacterial potency of phenolics drops of very quickly and becomes ineffective. Also of concern is toxicity- anything that kills microbes also may destroy or depress host cells numerous in vitro and in vivo studies have examined these toxicity factory.
INVITRO STUDIES: Under laboratory test conditions the ICM were highly effective in destroying or inhibiting the growth of microorganisms. Some of the medicaments accomplish this even in very low concentrations. To test the toxicity of medicaments the invitro study involves the use of cell cultures to determine the potency of the medicaments. If the medicament showed comparable cell destruction they were classified as toxic. If the results of the invitro tests were applied directly the medicament of choice would be iodine-potassium iodide. This demonstrates relatively high antibacterial activity and relatively low toxicity It has been suggested that sodium hypochlorite irrigant be utilized as an inter appointment medicaments, leaving the canals flooded rather than dry. IN VIVO STUDIES: This is done by intracanal sampling and culture techniques to test for the presence of bacteria, however this test is not precise and does not reflect the true status of the canal. Viable bacteria may remain untouched by the medicament and still not be recovered by bacterial sampling techniques. Important to note here is that phenolic type of ICM (CMCP & PCP) quickly lose their antimicrobial action when sealed in the pulp space, remaining bacteria would then proliferate and repopulate
Many
antimicrobial
agents
become
more
effective
at
higher
temperatures. Warming solutions to approximately 140’F (60’c) significantly enhances the antimicrobial activity in vitro of these solutions.
CONCLUSION: Every little drop makes an ocean. Similarly the introduction of intra canal medicaments to the endodontics armamentarium has added to the over all predictability of root canal therapy not with standing various controversies, intracanal medication still has a part to play in conventional endodontics. Their appropriate use by the informed clinician will aid in the ultimate success of root canal therapy.