Intracanal medicaments have been used to disinfect root canals between appointments and reduce interappointment pain. The disinfectants can be divided into phenolic compounds such as camphorated monochlorophenol, cresatin, aldehydes such as formocresol and glutaraldehyde, and halides, as well as other materials like calcium hydroxide [Ca(OH)2 ] and some antibiotics. These compounds are potent antibacterial agents under laboratory test conditions, but their efficacy in clinical use is unpredictable. Some of the aldehyde derivatives have been proposed to neutralize canal tissue remnants and to render them inert. These can be used to fix fresh tissues for histological examination, but they may not effectively fix necrotic or decomposed tissues. According to one report, fixed tissues are not inert and may become more toxic and antigenic after fixation. Intracanal medications have also been used clinically to prevent post-treatment pain. Studies have shown, however, that routine use of these materials as intracanal medications has no significant effect on prevention of pain.
Ca(OH)2 is a substance that inhibits microbial growth in canals. The antibacterial effect of Ca(OH)2 is due to its alkaline pH. It also dissolves necrotic tissue remnants and bacteria and their byproducts.It can be placed as a dry powder, a powder mixed with a liquid such as water, saline, local anesthetic or glycerin, or a proprietary paste supplied in a syringe. Because of its toxicity, Ca(OH)2 should be placed within the canal with the aid of a file or a needle. Extrusion of the material into the periapical tissues can cause tissue necrosis and pain for the patient. Ca(OH)2 can be removed from the canal by using irrigants such as saline, NaOCl or EDTA .
Corticosteroids are anti-inflammatory agents that have been advocated as intracanal medicaments to reduce postoperative pain. An animal study has shown a reduction of inflammatory cells in periapical tissues following supraperiosteal infiltration of dexamethasone into the buccal vestibule of rats. There is no significant clinical evidence that suggests that they are effective in patients with very high pain levels. The use of corticosteroids in patients with irreversible pulpitis and symptomatic apical periodontitis may be beneficial.
A 2% CHX gel has recently been advocated as an intracanal medicament. It can be used alone in gel form or mixed with Ca(OH)2 . When used for seven days to medicate bovine teeth or human teeth, CHX gel provides antimicrobial activity for up to 21 days after contamination. When it is used in combination with Ca(OH)2 , the antimicrobial activity of this mixture is greater than the combination of Ca(OH)2 and saline.
Bacteria are the major cause of pulpal and periapical diseases. Complexity of the root canal system, invasion of the dentinal tubules by microorganisms, formation of smear layer during instrumentation and presence of dentin as a tissue are the major obstacles for complete elimination of bacteria during cleaning and shaping of root canal systems. The bacterial population of infected root canals can be significantly reduced by using saline irrigation; however, irrigants that have antibacterial effects have clearly superior effectiveness in bacterial elimination when compared with saline solution. The irrigants that are currently used during cleaning and shaping include NaOCl, CHX, EDTA and MTAD. None of these irrigants has all of the characteristics of an ideal irrigant. Sonic and ultrasonic vibrations alone or in combination with antibacterial irrigants as well as application of negative pressure have been used to increase the efficacy of these irrigants. Intracanal medicaments have been used to disinfect root canals between appointments and reduce interappointment pain. The major intracanal medications currently used in endodontics include Ca(OH)2 and CH. The search for an ideal material and/or technique to completely clean infected root canals continues.
(American Association of Endodontists)