Research progress on QMix properties in root canal irrigation / 华西口腔医学杂志

Mechanical instrumentation preparation alone is insufficient to completely remove root canal infection, and chemical irrigation is essential to eliminate infected remnants. An ideal root canal irrigant should completely remove the smear layer, lubricate the root canal, efficiently kill bacteria, induce mild or no inflammatory response in the tissues, and avoid damaging the dentin structure. However, a commercial irrigant that meets all these requirements is currently lacking. QMix is a root canal irrigation mixture of ethylenediamine tetraacetic acid (EDTA), chlorhexidine (CHX) and surfactant. This mixture can remove the smear layer efficiently, and it possesses strong antibacterial effect and good biocompatibility with minimal cytotoxicity. Furthermore, the influence of QMix on the color and micro-hardness of dentin is low, and it can improve the wettability of root canal sealant without affecting its adhesive properties. This review compares the efficiencies of QMix with other irrigants (sodium hypochlorite, CHX, EDTA, SmearClear, and MTAD) in term of smear layer removal, dentine and root canal sealing, cell cytotoxicity, and bacterial growth inhibition.

Isolation and identification of aerobic and facultative anaerobic bacteria in the oral cavity / 南方医科大学学报

<p><b>OBJECTIVE</b>To establish a systematic method for isolation and identification of aerobic and facultative anaerobic bacteria in the oral cavity.</p><p><b>METHODS</b>Samples of the saliva, dental plaque and periapical granulation tissue were collected from 20 subjects with healthy oral condition and from 8 patients with different oral diseases. The bacteria in the samples were identified by morphological identification, VITEK automatic microorganism identification and 16s rRNA gene sequencing.</p><p><b>RESULTS</b>VITEK automatic microorganism identification and 16s rRNA gene sequencing showed an agreement rate of 22.39% in identifying the bacteria in the samples. We identified altogether 63 bacterial genus (175 species), among which Streptococcus, Actinomyces and Staphylococcus were the most common bacterial genus, and Streptococcus anginosus, Actinomyces oris, Streptococcus mutans and Streptococcus mitis were the most common species. Streptococcus anginosus was commonly found in patients with chronic periapical periodontitis. Streptococcus intermedius and Staphylococcus aureus were common in patients with radiation caries, and in patients with rampant caries, Streptococcus mutans was found at considerably higher rate than other species.</p><p><b>CONCLUSION</b>Aerobic and facultative anaerobic bacteria are commonly found in the oral cavity, and most of them are gram-positive. 16s rRNA gene sequencing is more accurate than VITEK automatic microorganism identification in identifying the bacteria.</p>