Background Survival of endodontically treated teeth depends on an efficient restoration of the missing tooth structure. Objectives This study aimed to investigate the mechanical properties of different endodontic post systems. Materials and methods Human permanent maxillary central incisors (no.=58) were decoronated and root-filled. The specimens with prepared root canals were randomly divided into Group P: Polyether Ether Ketone (PEEK) post and composite core and Group C: custom-made post-core of PEEK. The cementation of the posts was carried out using self-adhesive resin cement. Nano-hybrid composite resin was used for core fabrication. After cementation, the specimens from each group were randomly divided into two subgroups according to the types of tests utilized: 14 from each group were for the fracture strength test, which was restored with IPS e-max CAD crown, and 15 from each group for the pullout resistance test. A universal testing machine was used for the test performance. Results The fracture resistance test showed that the values significantly differed among tested posts (P = 0.013). Group P showed the highest fracture resistance. Group C exhibited higher mean pullout resistance values than the other group (P) (P = 0.059). In the two-piece PEEK post and composite core, the predominant type of failure was a core fracture, while in the one-piece PEEK post-core, most types of failures were either in the crown or in the post. Conclusions The prefabricated posts are more resistant to fracture than the custom-made posts, with fracture and displacement mainly of the core. In contrast, both showed similar pullout resistance.

Background Currently, the demands for restorations have increased considerably; thus, improvements and modifications have been made in dental composite technologies especially using materials that have been claimed to improve color stability. Objective This study aimed to determine the effect of various solutions on the color stability of different restorative materials in vitro study. Methods This study used three types of esthetic restorative materials. The samples comprised 45 discs, including 15 micro-hybrids, 15 nano-hybrids, and 15 glass ionomers). These discs were immersed in various beverages an hour a day for one month at room temperature. The color stability was measured using a spectrophotometer before/after immersion (days 7 and 30). Results We realized a significant difference in color change with Coca-Cola and tea-milk solution after seven days and 30 days (p < 0.05). However, no significant difference was found in the samples immersed in DM after seven days and 30 days (p > 0.05). The highest value of lightness (∆L) and stainability (∆a) was seen in micro-hybrid after 30 days of immersion in tea-milk solution (− 12.16 ± 1.74 and 11.4 ± 3.82, respectively), while most samples had a positive ∆b value. Conclusion After one month, the tea-milk solution affected the color stability of all used restorative materials. In addition, micro-hybrid had higher color stability than nano-hybrid and glass ionomer.

Purpose. This study evaluates the effect of bleaching before or after veneer preparation and the depth of preparation on color masking ability of laminate veneers. Methods. Sixty extracted premolars were artificially stained to vita shade A4, verified by digital spectrophotometer (Vita Easy Shade V), and then divided into three groups: NB = nonbleached , BBP = bleaching before preparation, and BAP = bleaching after preparation. Based on the preparation depths, each group was further divided into two subgroups: S 1 = 0.5   mm and S 2 = 1.0   mm . BBP and BAP were subjected to one session of in-office bleaching using 35% hydrogen peroxide. IPS e-max CAD veneers of 0.5 and 1.0 mm thickness (corresponding to the preparation depths) of the same shade and translucency (HT A1) were cemented immediately to the bleached surfaces. Immediately after cementation, the color change Δ E between the baseline (after staining) and the resulted shades was measured using the Vita Easy Shade V digital spectrophotometer and CIELab color system. Results. Bleached groups exhibited a significant Δ E value compared to the nonbleached group ( p < 0.05 ). BAP showed the highest Δ E value. No significant difference was found between BBP and BAP. S2 revealed a significant Δ E value than S1 ( p < 0.05 ). No significant difference was found between S1of BAP and S2 of NB, BBP, and BAP ( p > 0.05 ). Regarding the color coordinates, the difference between the tested groups was highly significant in lightness ( Δ L ∗ ) ( p < 0.001 ), while no significant differences were found in green/red value ( Δ a ∗ ) and yellow/blue value ( Δ b ∗ ) ( p > 0.05 ). Conclusions. In cases of severe tooth discoloration, one session of in-office bleaching before or after veneer preparation and the preparation depth do not influence the color masking ability of laminate veneers.

Background Survival of endodontically treated teeth depends on efficiently restoring the missing tooth structure. Objectives This study is designed to assess the mechanical properties of different endodontic post systems. Materials and methods Human permanent maxillary central incisors (no.=58) of the same size were decorated and root-filled, and the post spaces were prepared up to 9.0 mm. Then, the specimens with prepared root canals were randomly divided into two groups; Group P allocated a prefabricated polyetheretherketone (PEEK) post and composite core, while Group C allocated a custom-made post-core of PEEK. The cementation of the posts was carried out using self-adhesive resin cement, while the nano-hybrid composite resin was used for core fabrication. After cementation, the specimens from each group were randomly divided into two subgroups according to the types of tests utilized. Of these, 28 samples (14 from each group) were for the fracture strength test, which was restored with IPS e-max CAD crown, and 30 samples (15 from each group) for the pullout resistance test. A universal testing machine was used for the test performance. Results The fracture resistance test showed that the values were significantly different among tested posts (P = 0.013). Group P showed the highest fracture resistance. The custom-made one-piece post and core PEEK post group (C) exhibited higher mean values of pullout resistance compared with the other group (P) (P = 0.059). In the two-piece PEEK post and composite core, the predominant type of failure was core displacement or fracture, while in the one-piece PEEK post-core, most types of losses were either in the crown or in the post. Conclusions The prefabricated posts are more resistant to fracture than the custom-made posts with fracture and displacement mainly of the core. In contrast, both showed similar pullout resistance.