Evaluation of Antimicrobial Activity of Propolis on Regenerative Potential of Non-vital Immature Root Apex in Dogs

Abstract

The present study was conducted to assess the antibacterial efficiency of Propolisduring preparation of infected root canal and its ability to promote regeneration for the treatment of immature non-vital dogs’ teeth. A total of six mongrel dogs aged approximately 4-6 months were selected for this study. The four premolars in each quadrant were included in the study summing up the total number of teeth to 96 (16 teeth/dog).72 samples were used as an experimental group and 24 samples were used as a control group. The 72 samples were classified into two main equal groups according to the type of intrcanal medication used: group (I):root canals medicated with pure paste of Propolis, group (II):root canals medicated with TAP, each group was further subdivided into two subgroups according to the type of regenerative material used: subgroup (A): Propolispaste as root canal orifice plug subgroup (B): MTA as root canal orifice plug, each subgroups was further subdivided into three subdivisions according to the post treatment evaluation period (2 dogs were scarified for histological evaluation in each period) , Subdivision (1): after 2 weeks, Subdivision (2): after one month, Subdivision (3): after 2 months. While the 24 samples were classified into Positive and Negative Control Groups as follows: Positive control group(12 samples - 4 premolars for each period of evaluation): with induced periapicalinfections without any treatment modalities and left open, Negative control group(12 samples - 4 premolars for each period of evaluation): sound teeth left for normal maturation. Anti-microbial effectiveness for all samples of group (I) and group (II) were assessed; pre exposure to intracanal medicaments bacteriologic sampling was done, propolis and TAP were introduced to all canals and post exposure to intracanal medicaments bacteriologic sampling was done. Antibacterial effectiveness of the different intracanal medicaments were assessed by determining the percentage of reduction in colony counts (%RCC) before and after placement of the intracanal medicaments.Data were collected, tabulated and statistically analyzed. Histological evaluation includedquantitative analysis (presence or absence of new hard tissue on the internal root canal walls, presence or absence of vital tissue within the canal space, and presence or absence of apical closure) and qualitative analysis for identification of newly formed hard and soft tissue structure. Data were collected, tabulated and statistically analyzed. Radiographic evaluation included measuring increase in length, thickness and occurrence of apical closure. Radiographs were standardized using Image-J software with TurboReg plug-in. Increase in length and thickness were measured in each subgroup, data were collected and statistically analyzed. Apical closure score were counted and data were statistically analyzed. Phase I (Antimicrobial Effectiveness): Results showed that at base line and after three weeks there was no statistically significant difference between TAP and Propolis groups; both showed statistically significantly lower mean values. Phase II (Regeneration): Radiographic evaluation: Results showed that through all periods of evaluation there was no statistically significant difference between Propolis and MTA subgroups; all showed statistically significant high mean percentage change in root length, dentin thickness and apical closure. The negative control group showed the highest mean percentage change and the positive control showed the lowest mean change in root length, dentin thickness and apical diameter. Histologic evaluation: Quantitative analysis: Through all evaluation periods; there was no statistically significant difference between Propolis and MTA subgroups they showed statistically higher mean new hard tissue score, vital tissue score as well as apical closure score. Negative control group showed statistically the highest mean scores while positive control group showed statistically the lowest mean hard and vital tissues scores.