الفهرس 
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Abstract
Introduction:
Dental plaque plays a major role in the etiology of dental caries.4 It has been identified that a diverse microflora is found in dental plaque biofilms. Therefore, “The specific plaque hypothesis” was put forward as a major advance.5 This hypothesis proposed that the disease is actively caused by only a few of the many species found in dental plaque biofilms. Thus, we can control caries disease by targeting preventative measures and interventions against these ‘‘specific’’ organism 20.
Over the years, various synthetic chemical agents have been evaluated for their antimicrobial effect in oral cavity. The chlorhexidine remains the benchmark control in the removal of plaque accumulated over enamel surface 8. However, it cannot be used for a long period of time due to its many side-effects like altered taste sensation and staining of tongue 9.
Accordingly; patients are preferring to shift away from modern medicines, and they prefer using herbal preparations like Terminalia chebula, Aloe Vera, Azadirachta indica, piper betle, Ocimum sanctum11.
Aloe Vera extract has been considered as one of the natural oral hygiene aids to reduce plaque formation and accumulation. Aloe Vera was used for many and different treatments like burns, hair loss, skin infections, haemorrhoids, sinusitis, and gastrointestinal pain 156. It is also a wound healer for bruises, insect bites147.
Literature is abundant on the health beneficial effects of Aloe Vera but to date, few studies have been conducted to test its antibacterial efficacy on enamel surface. 4,16,157–159 Hence, this study was conducted to evaluate the efficacy of Aloe Vera as antibacterial agent.
Materials and Methods:
This in-vitro study was conducted at the Department of Microbiology, of Ain Shams University.
To evaluate the antibacterial activity, three commercial toothpastes were used which are:
1. Aloe vera containing toothpaste (Hello, Hello production LLC, United States)
2. Fluoride containing toothpaste (Signal Kids, Unilever Mashreq, Egypt)
3. Chlorohexidine containing toothpaste (ELGYDIUM, Pierre Fabre Medicament, France)
Methodology:
Freshly collected Aloe Vera gel was obtained from cutting it into half and the inner flesh (Mucin) was extracted using a dental carver and inserted into sterilized vial until conduction of the test at room temperature 24C.
This study used freeze dried stock culture of the reference strains Streptococcus Mutans (France, imported by El Magd company, derived from ATCC 35668TM, Lot no. 969-51-2, Ref.no. 0969P) and Lactobacilus Acidophilus (France, imported by El Magd company, Lot no. 885-43-4, Ref.no. 0885P).
Tests:
Direct contact test:
For testing the antibacterial effect of each material, a two 96 well plates were used (one plate for SM and second one for LB). The plates were held vertically, and the sidewalls of the wells were coated with thin layer of the materials. A 10 µl bacterial suspension of the previously mentioned strains (approximately 106 bacteria) was placed on the tested materials. Afterwards incubation of the wells vertically for 1 h in a humid atmosphere at 37°C was carried out where evaporation of the suspension’s liquid was observed to ensure direct contact between all tested bacteria and surfaces of the tested materials. The plates were then positioned horizontally and 245 µl of BHI (brain heart infusion) broth were added to each well containing the material and incubated for 1 hour. The optical densities of bacterial growth were measured using Spectrophotometer at 600 nm wavelength after incubation for 5 days.
Agar diffusion test:
A 200 µl of bacterial suspension mentioned previously (approximately 5x107 colony-forming units) were spread on blood agar plates. Each tested material(10 µl )from the 3 toothpastes under study and the clorhexidine liquid, fluoride liquid and Aloe Vera gel were inserted into uniform wells that were previously punched (4 mm diameter and 4 mm depth) in the agar. After incubation at 37°C for 48 hours, the agar plates were examined for bacterial inhibition zones. The diameter of the inhibition zone was measured in millimetres in two perpendicular locations for each sample 160.
Contact angle measurement:
The extracted teeth were rinsed thoroughly using distilled water. 161 Each tested material was applied on the tooth using a manual toothbrush (Oral B). Brushing was done for nine minutes and 10 seconds which was assumed to be the equivalent of brushing for two months and then rinsed using distilled water127.
Static contact angles was measured with the sessile DROP method of artificial saliva drops at room temperature. 128 An image was then captured, and the contact angle was calculated using the tangent method.126
Statistical analysis:
Repeated measures ANOVA test was used to compare between the groups. Bonferroni’s post-hoc test was used for pair-wise comparisons. Statistical analysis was performed with IBM SPSS Statistics for Windows, Version 23.0. Armonk, NY: IBM Corp.
Results:
Direct contact test:
After five days of both SM and LB incubation; there was a statistical significant difference between the groups. Pair-wise comparisons between the groups revealed that fluoride toothpaste showed the highest statistical significant mean OD. While chlorhexidine toothpaste showed a lower statistical significant mean OD. Aloe Vera toothpaste showed the lowest statistical significant mean OD.
Agar diffusion test:
As regards SM; there was a statistical significant difference between the groups (P-value <0.001, Effect size = 0.691). Pair-wise comparisons between the groups revealed that Aloe Vera toothpaste group showed the highest mean value with no statistical significant difference from fluoride control group. While it showed a statistical significant difference with all other groups. Fluoride control group showed no statistical significant difference from chlorhexidine toothpaste and chlorhexidine control groups. The lowest mean value was obtained with fluoride toothpaste group with no statistical significant difference from Aloe Vera pure gel group and showed a lower statistical significant mean value compared to other groups.
As regards Lactobacilli; there was a statistical significant difference between the groups (P-value <0.001, Effect size = 0.481). Pair-wise comparisons between the groups revealed that Aloe vera toothpaste group showed the highest mean value with no statistical significant difference from flouride toothpaste group. While it showed a statistical significant difference with all other groups. Aloe vera pure gel group showed the lowest mean value with no statistical significant difference from chlorhexidine toothpaste, chlorhexidine control and fluoride control groups.
Contact angle measurement:
As regards the percentage change in contact angle after application; there was a statistical significant difference between the groups (P-value <0.001, Effect size = 0.421). Pair-wise comparisons between the groups revealed that there was no statistical significant difference between Aloe vera toothpaste, chlorhexidine control and fluoride toothpaste groups; all showed the highest statistical significant mean percentage decrease in contact angle. Fluoride control group showed a lower statistical significant mean percentage decrease in contact angle. There was no statistical significant difference between Aloe vera pure gel and chlorhexidine toothpaste; both showed the lowest statistical significantly mean percentage decrease in contact angle.