Avicenna's views on pest control and medicinal plants he prescribed as natural pesticides.

The present study aimed to introduce Avicenna's views on pest control and the medicinal plants he proposed as natural pesticides. Also, we addressed the strategies that he leveraged to formulate and prescribe them, and, finally, we put his views into perspective with modern science. The data were collected using Al-Qanun Fi Al-Tibb (The Canon of Medicine) as well as scientific databases. According to Al-Qanun Fi Al-Tibb, 42 medicinal plants are described as natural pest control agents. After introducing the pest control properties of each plant, Avicenna explained the appropriate strategies for use of these plants. These strategies or formulations included incensing, spraying, spreading, rubbing, smudging, and scent-dispersing, which are equivalent to the modern pesticide formulations of fumigants, aerosols, pastes and poisoned baits, lotions, creams, and slow-release formulations, respectively. This study revealed that Avicenna introduced the pest control approach with natural plants in his book Al-Qanun Fi Al-Tibb and, thus, harnessed the power of nature to control nature. Future research is recommended to find the pest control merits of the presented medicinal plants, in order to incorporate them into pest control programs and reduce environmental pollution resulting from the complications of current synthetic pesticides.

Influence of resin cement on color stability of ceramic veneers: in vitro study.

STATEMENT OF THE PROBLEM: Long-term success of ceramic veneers depends on the color stability of resin cement used for their cementation. Color change of cement may be seen through the ceramic and compromise esthetics. PURPOSE: This study aimed to compare the color change of two resin cements and their visibility through the ceramic veneers after accelerated artificial aging. MATERIALS AND METHODS: In this in vitro study, color change (ΔE) was measured in the following groups (n = 10) before and after accelerated artificial aging: group 1, IPS e.max press high translucent ceramic discs; groups 2, Variolink NLC resin cement discs; group 3, Choice 2 resin cement discs; groups 4, Variolink NLC discs bonded to e.max ceramic discs; group 5, Choice 2 disc bonded to e.max ceramic discs. Color change was measured using a spectrophotometer according to International Commission on Illumination Lab (CIELab). Data were analyzed using one-way ANOVA and Tukey's post-hoc test. RESULTS: Group 2 showed the highest (ΔE = 10.4 ± 0.9) and group 1 the lowest (ΔE = 0.9 ± 0.4) color change. The color change of Variolink was significantly greater than Choice 2 either alone (p < .001) or through the ceramic discs (p < .004). The color change of both cements was lower through the ceramic veneer and this reduction was statistically significant (p < .001). CONCLUSION: Noticeable color change may be expected in areas of cement exposure for both cements studied. Also, in case of using Variolink cement, the color change may be seen through the ceramic veneers.