The Synergistic Effect of Aqueous Extracts of Iraqi Propolis and CPP-ACPF Paste on Enamel Microhardness after Demineralization Challenge

Aims: This study endeavors to estimate the synergistic effect of aqueous extracts of propolis on microhardness power of fluoridated CPP-ACP (MI plus) paste after demineralization challenge. Materials and methods: A total of (75) posterior wisdom teeth were used in the study. Enamel blocks were prepared and divided into five groups randomly, the teeth in all groups were subjected to demineralization cycle and then treated with: Sinjar's aqueous extract of propolis (AEP) -MI paste plus cream n. (15), Sulaymaniah's AEP-MI paste plus cream n. (15), Duhok's AEP-MI paste plus cream group n. (15), control positive group of MI paste plus alone n. (15), and control negative group of artificial saliva alone n. (15). Microhardness of enamel blocks was measured using Vickers microhardness tester machine at base line, after demineralization cycle and finally after treatment protocol. Results: Statistically, there were highly significant differences among study groups after demineralization cycle and there was a decrease in surface microhardness in all groups after demineralization, but the least reduction in surface microhardness belonged to mixture of Sulaymaniah's aqueous extract of propolis with MI paste plus followed by MI paste plus alone group after treatment protocol. Conclusions: Mixture of Sulaymaniah's aqueous extract of propolis with MI paste plus was significantly better than MI past plus alone in preserving enamel's hardness and resisting the demineralization challenge.


INTRODUCTION
Demineralization of enamel leads to the appearance of white spot lesions, also it leads to the dissolution of apatite crystals and the net loss of calcium, phosphate, and other ions from the tooth. The objective of contemporary dentistry is to manage non-cavitated caries lesions non-invasively through remineralization in an attempt to inhibit the progression of dental disease (1) .  (6) .
A new alternative to dental caries prevention is the development of natural materials as propolis and propolis` fluoride. The choice of natural-based medicines is based on the fact that the side effects of traditional medicine are lesser than chemical or synthetic drugs (7) . Propolis is a natural substance collected by honey bees from different plants (8) . It has anti-microbial and antiinflammatory properties owing to the presence of flavonoids (9) . In dentistry, propolis has been used for the treatment of gingivitis, periodontitis, candidiasis, aphthous ulcers, and pulpitis (10) and for prevention of dental caries lesions (11) .
The aim of the current study is to speculate the synergistic effect of aqueous extracts of propolis on the microhardness power of fluoridated CPP.ACP paste after demineralization challenge.

MATERIALS AND METHODS
The study was approved by Re-

Collection and Extraction of Propo-
The unrefined propolis (Apis mellifera) was obtained from three different regions in the North of Iraq. The first type was from Sinjar's mountains/Nineveh, the second type was from Duhok's mountains and the third one was from Sulaymaniah's mountains. For aqueous extract preparation, Krell method (12) was followed. The extract was clear from any impurities, dark and viscous and its odor is also distinguishable for each specific type (13) .

Coating Complex
Both ingredients were com-  were stored in 0.1% thymol solution at 4ºC (14) to avoid dehydration and prevent bacterial growth until their use within three months.

Preparation of Enamel Blocks
Sound extracted third molars were cleansed accurately before using, they

Design of Study and Methods of application
The total number of teeth samples in the study was (75) samples, randomly divided into five groups, (15) samples in each group as follows:

RESULTS
The data were analyzed using SPSS program (version 19). showed that there was a highly significant difference at p ≤ 0.01 of mean mi-crohardness values among tested groups in the three stages of the study.  .
On the other hand, Soekanto et al. Ordinarily, because of the high content of impurities which must be removed raw propolis is not suitable for pharmaceutical or cosmetic industry applications and food technology (28) . .Also, propolis reduced accumulation of dental plaque and its insoluble external polysaccharide content (31) . On the other hand, propolis is a non-toxic material and its antimicrobial activity is related to the presence of flavonoids and terpenoids (32) . It contains minerals such as magnesium, iodine, potassium, sodium, copper, zinc, manganese, iron (33) .Also calcium, phosphate and fluo- ter extracts (44) . Moreover, the aqueous extract resulted in antibacterial activity. A previous study was observed by Garedew et al. (2004) (45)  ical origin (46) .

Limitations of the study:
The major limitation of this study is that it is an in vitro study in which demineralization cycle was obtained by using chemical products, and did not happen due to the presence of Streptococcus mutans and its acid byproducts.