Abstract:

Elimination of microorganisms from the root canal system is one of the objectives of the root canal treatment and has a substantial effect on the treatment outcome. Accepted treatment procedures to eliminate the infection include a combination of chemo-mechanical debridement, application of an inter appointment dressing containing an antimicrobial agent and finally sealing of the root canal. Unfortunately, micro organisms may remain after conventional canal preparation, either within the dentinal tubules or bound within the apical dentin plug. Therefore for complete eradication of infection, the pulpal remnants as well as smear layer should be removed from the root canals.

Some investigators recommend the use of calcium hydroxide as an intracanal dressing in a multiple-visit approach. The environment within the system, however, is such that delivering the medicament and maintaining a high pH homogeneously is a challenge. For these and other reasons, certain microbial species in a limited group of cases do survive and can be responsible for persistent infections (1,2). Thus, the search for a better alternative has led to the discoveries of newer antimicrobial agents.

 The Cariology Research Unit of the Niigata University has developed the concept of ‘Lesion sterilization and tissue repair LSTR’ therapy (3,4) that employs the use of a combination of antibacterial drugs for disinfection of oral infectious lesions, including dentinal, pulpal, and periradicular lesions. Repair of damaged tissues can be expected if lesions are disinfected (5). Metronidazole was the first choice because it has a wide bactericidal spectrum against anaerobes (6), which were common in oral sites. However, some bacteria in lesions were resistant to metronidazole and, thus, two other antibacterial drugs, e.g., ciprofloxacin and minocycline, should be mixed with metronidazole (7) in an effort to eliminate all the bacteria. Finally, extensive in vitro and in situ studies have been conducted showing the mixed drugs to be effective against oral bacteria (5,8,9). The disadvantage of this mixture is the discoloration caused by minocycline present in it (10).

In recent years novel antimicrobial approaches to disinfect root canals have been proposed that include Photo Activated Disinfection [PAD]. PAD uses a combination of photosensitising dye, such as Tolonium chloride solution [TC] [synonym Toluidine Blue O], and light of a specific wavelength. This combination using light at 633G2 nm has been shown to kill high numbers of bacteria in planktonic suspension, probably by disruption of the bacterial membrane by short range free radicals or reactive oxygen species. TC is unchanged by the process, which ceases when irradiation stops (11).

The present study was designed to evaluate clinically and radiographically the healing of periapical lesions using triple antibiotic paste, PAD and calcium hydroxide when used as root canal disinfectant. 

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