Background/aim The interest in herbal products has increased in the last years because of their limited adverse effects. The aim of this study was to evaluate the remineralization effect of green coffee on demineralized enamel in comparison with green tea. Materials and methods A total of 42 crowns of primary molars were divided equally into buccal and lingual segments (84 totals). Each specimen was embedded into an acrylic block and then immersed in Red Bull for 4 h. The specimens were divided into two groups according to the type of remineralizing solution used: group 1 using green tea and group 2 using green coffee. In each group, the buccal halves were subjected to microhardness test, whereas the lingual halves were subjected to scanning electron microscopy and energy-dispersive radiograph analysis examinations. Results The results of scanning electron microscopy revealed a demineralization effect after immersion into Red Bull, which decreased after immersion into both remineralizing solutions of green tea and coffee. The energy-dispersive radiograph analysis showed a decrease in calcium and phosphorous weight% after demineralization, which is increased after remineralization with both solutions. The microhardness test revealed a decrease in surface hardness after demineralization, which increased after the remineralization process. Moreover, in comparing the two remineralizing solutions, the remineralization effect of green coffee was statistically higher than that of green tea. Conclusion Green coffee has an efficient remineralizing effect than green tea, which was superior in treatment of initial caries.

Background and aim Treatment of mandibular edentulous ridge with all-on-four treatment concept is a reliable choice. However, the framework material may affect the stresses transmitted to the implant and bone. The aim of the study was to compare stresses transferred to implant–bone interface on using glass fiber-reinforced composite (GFRC), zirconia (Zr), titanium (Ti) and poly-ether-ether-ketone (PEEK) as framework materials. Patients and methods Three-dimensional finite element model of completely edentulous mandible restored with four implants (two axial anterior implants and two posterior implants 30° distally tilted) connected with a framework of different materials (Zr, Ti, GFRC, and PEEK) was constructed. A unilateral axial load of 250 N was applied at the distal end of the cantilever and the resultant von Mises stresses at implant–bone interface were calculated. Results The lowest von Mises stresses at implant/crestal bone area was recorded with Zr framework followed by Ti then GFRC while the highest von Mises stresses were recorded with PEEK framework. Conclusions Within the limitations of this study, it could be concluded that the stiffer framework material transmits more stresses to the implants. The stress distribution of GFRC, as a framework material, is better than PEEK.