Microbiological assessment and effect of calcium hydroxide/chlorhexidine paste as intracanal medicament in human primary teeth with necrotic pulp

Abstract

The maintenance of deciduous teeth carring out their function in oral cavity until the physiologic exfoliation is very important to the correct development of permanent dentition. Therefore, the preservation of necrotic deciduous teeth has been a serious challenge. The success of endodontic treatment depends on several factors, and the reduction or elimination of bacterial infection is the most important one. However, for this to occur, it is fundamental to identify which microorganisms are involved in the process. There are few studies concerning to identify the specific microbiota in root canals of deciduous teeth with necrotic pulp and to verify the effectiveness of intracanal dressings on eliminating the residual infection, which make difficult to arrive to a counsensus at different Dental Schools. Actually, there are accurate and sensible molecular techniques that have been used to identify and quantize specific pathogens present in root canals in real time. However, little research has been done to detect specific microorganisms in deciduous teeth with necrotic pulp. Therefore, the aim of this study is to identify and quantize target bacteria present in root canals of human deciduous teeth with necrotic pulp and with or without periapical lesions; to evaluate the effectiveness of different intracanal dressings and to evaluate clinical and radiographic success of the treatments. In this study, 16 deciduous teeth with necrotic pulp and periapical lesions and 16 deciduous teeth with necrotic pulp without periapical lesions will be used. After biomechanical preparation, these teeth will be divided in two different groups according to intracanal dressing used: GI - calcium hydroxide based paste, and GII - calcium hydroxide based paste combined with chlorhexidine gel. Each tooth will be considered an experimental unit. An initial bacteriological sample will be collected introducing sterile absorbent paper points in the root canal just after crown access. A second bacteriological collect will be done after biomechanical preparation and a third bacteriological collect will be done after the time required by each intracanal dressing. The root canals will be filled with calcium hydroxide based paste thickened with zinc oxide. Subsequently, the total genomic DNA of each bacteriological sample will be extracted. The identification and quantification of specific pathogens present in root canals at each evaluation clinical period will be done by Real-time quantitative PCR technique. After conclusion of endodontic treatments, the success will be evaluated by periodic clinical and radiographic examinations during 180 days.