Tetraclean (Ogna Laboratori Farmaceutici, Muggio, Italy) is a combination product similar to MTAD. The two irrigants differ in the concentration of antibiotics (doxycycline 150 mg/5 ml for MTAD and 50 mg/5 ml for Tetraclean) and the kind of detergent (Tween 80 for MTAD, polypropylene glycol for Tetraclean).

Mode of Action

All tetracyclines are derivatives of four-ringed nucleus that differ structurally in regard to the chemical groups at 2, 5, 6, and 7 positions. These derivatives exhibit different characteristic such as absorption, protein binding, metabolism, excretion, and the degree of activity against susceptible organism [31]. Tetracyclines inhibit protein synthesis by reversibly binding to the 30S subunit of bacterial ribosome in susceptible bacteria. It is effective against Aa. capnocytophaga, P.gingivalis, and P. intermedia and affects both gram-positive and gram-negative (more gram-negative effect). Tetracycline is a bacteriostatic antibiotic, but in high concentrations, tetracycline may also have a bactericidal effect. Doxycycline, citric acid, and Tween 80 together may have a synergistic effect on the disruption of the bacterial cell wall and on the cytoplasmic membrane.

Smear Layer Removal

In two studies, the efÞcacy of MTAD or EDTA in the removal of the smear layer was conÞrmed, but no signiÞcant difference between these two solutions was reported [87, 88].

Antibacterial Efficacy

Earlier in vitro research on MTAD showed its antimicrobial efficacy over conventional irrigants [15, 87, 88]. Torabinejad et al. [15] found that MTAD was effective in killing E. faecalis up to 200× dilution. Shabahang and Torabinejad [76] showed that the combination of 1.3 % NaOCl as a root canal irrigant and MTAD as a final rinse was significantly more effective against E. faecalis than other regimens [75]. A study using extracted human teeth contaminated with saliva showed that MTAD was more effective than 5.25 % NaOCl

in disinfection of the teeth. In contrast to the previously mentioned studies, later research suggested less than optimal antimicrobial activity of MTAD [21, 41]. Krause et al. [46], using bovine tooth sections, showed that 5.25 % NaOCl was more effective than MTAD in disinfection of dentin disks inoculated with

E. faecalis [76, 79].

Clinical Trials

Malkhassian et al.[55] in a controlled clinical trial of 30 patients reported that the Þnal rinse with MTAD did not reduce the bacterial counts in infected canals beyond levels achieved by chemomechanical preparation using NaOCl alone.

Protocol for Use

MTAD was developed as a Þnal rinse to disinfect the root canal system and remove the smear layer. The effectiveness of MTAD to completely remove the smear layer is enhanced when a low concentration of NaOCl (1.3 %) is used as an intracanal irrigant before placing 1 ml of MTAD in a canal for 5 min and rinsing it with an additional 4 ml of MTAD as the Þnal rinse [79].

QMiX

QMiX was introduced in 2011; it is one of the new combination products introduced for root canal irrigation. It is recommended to be used at the end of instrumentation, after NaOCl irrigation. According to the patent (195), QMiX contains a CHX analog, triclosan, (N-cetyl- N,N,N-trimethylammonium bromide), and EDTA as a decalcifying agent; it is intended as a antimicrobial irrigant as well as to be used in the removal of canal wall smear layers and debris.

Protocol

QMiX is suggested as a Þnal rinse. If sodium hypochlorite was used throughout the cleaning and shaping, saline can rinse out NaOCl to prevent the formation of PCA.