This study aims to examine color properties of repairs made with various composites on restorations produced through additive-manufactured resin composites (AM-RC) and zirconia (AM-Z) or subtractive manufacturing (SM) after coffee thermocycling (CTC). Disk-shaped specimens (Ø10 × 2 mm; N = 120) were fabricated using six different material groups: additively manufactured resin composite (AM-RC) materials (Crowntec [C], NextDent [ND]), additively manufactured zirconia (AM-Z) materials (Lithoz [LI], INNI-Cera [IN]), and subtractively manufactured (SM) materials (CEREC Tessera [ALD], Vita Enamic [EN]). Subsequently, each group was further subdivided into two subgroups (n = 10) based on the type of repair using two different composites resins: Clearfil Majesty Posterior (CL) (n = 60) and Filtek Z350 (FZ) (n = 60). Specimens underwent thermal cycling (CTC), consisting of 10,000 cycles between 5 °C and 55 °C. Color measurements were performed both before and after thermal cycling for all materials. Color discrepancies (ΔE00) and relative translucency parameters (RTPs) were calculated. Statistical analyses were conducted at a significance level of α = 0.05. A one-way ANOVA of ΔE00 values between CL and FZ revealed a significant difference (P = 0.007), with FZ exhibiting higher ΔE00 values. Significant differences in ΔE00 values were also observed among IN, C, and ND after CTC (P < 0.05). ALD demonstrated the lowest amount color change (P < 0.05). LI and EN colors showed no significant difference (P = 0.75). Following CTC, C, ND, and IN colors matched CL. In contrast, ALD, EN, and L colors exhibited significant differences (P ≤ 0.050). FZ showed a poor color match with all AM and SM materials. Furthermore, significant differences in RTP values were identified for all specimens (P < 0.001), with LI having the highest RTP and IN the lowest (P < 0.001). The optical properties of composite and ceramic materials, as well as their stability over time, are crucial for their durability. ALD demonstrated the most consistent color stability. While the CL repair composites experienced some color changes, these changes remained within acceptable limits. Additionally, the LI (AM-Z) material exhibited the highest level of translucency.

The aim of this study is to assess color stability, solubility, and water sorption on polyether ether ketone (PEEK) and polyether ketone ketone (PEKK) after immersion in different storage conditions. Material and Methods Ninety disc-shaped specimens (8 × 2) were obtained from CAD/CAM blocks [PEEK (n = 45) and PEKK (n = 45)]. Before immersion, baseline color value data were recorded with a spectrophotometer. The specimens were soaked in three solutions red wine, coffee, and distilled water at 37 °C for 28 days. Following immersion, color values were remeasured, and color-change values (ΔE) were calculated. Water sorption and solubility were assessed by mass gain or loss after storage in water for 28 days. The Kruskal–Wallis and the Mann–Whitney U test were used for analysis (P = 0.05). Results ΔE00 between PEEK and PEKK was significantly different statistically (P < 0.001). PEEK presented higher water sorption than PEKK (P = 0.005). The difference in solubility between PEEK and PEKK was not statistically significant (P = 0.163). The materials and storage medium types had a statistically significant impact (P = 0.100). In terms of staining potential, the solutions tested in this experiment were ranked as: coffee > red wine > distilled water. The results of this study demonstrated that PEKK was more successful in polymer-containing CAD/CAM materials as it exhibited less color change and water absorption.

To evaluate the influence of polydopamine (PDA) treatment on bond strength, fracture, and wear resistance of occlusal veneers (OVs) fabricated using additive (AM) and subtractive manufacturing (SM) techniques. Three hundred twenty 0.5 mm-thick OVs were fabricated through AM and SM and from four groups of materials (n = 80): AM ceramic-filled resin (AM-C), AM zirconia (AM-Z), SM nano-ceramic resin (SM-C), and SM zirconia (SM-Z). Each group was further divided into PDA-treated and untreated subgroups (n = 40). Specimens were cemented onto resin dies using self-curing resin cement (Multilink N; Ivoclar Vivadent) and subjected to five million chewing cycles with thermal cycling. Fracture and wear resistance were assessed using a load-to-failure test and 3D surface analysis, respectively (n = 20). Additionally, bond strength was evaluated using a pull-out test (n = 20). Data were analyzed using three-way ANOVA to assess the main and interaction effects of material, manufacturing technique, and PDA treatment (α=0.05). Significant main effects of manufacturing technique, material type, and PDA treatment were found for all outcomes (p<.001), along with significant manufacturing × PDA interactions. PDA notably improved fracture resistance and bond strength in AM-Z and AM-C (p<.05), but had minimal effect on SM groups. Wear was significantly reduced in AM groups following PDA (p<.001), while SM-C showed a slight increase (p=.021). Among all groups, untreated AM-C demonstrated the weakest overall mechanical performance. PDA treatment enhanced fracture and bond strength in AM materials, with limited effect on SM ceramics. Milled zirconia showed the best overall performance, while untreated AM-C consistently performed the worst. Polydopamine surface treatment enhances the mechanical performance of occlusal veneers fabricated by additive manufacturing, particularly improving bond strength and fracture resistance. This approach may increase the clinical reliability of 3D-printed restorations, especially in thin, conservative designs.

Objective: The aim of this study was to evaluate the effect of different polishing systems on the colour stability of different laminate veneer blocks for chair-side CAD-CAM after ultraviolet (UV) ageing. Methods: About 240 sample (13 × 13 × 0.7) were prepared from four different CAD-CAM blocks IPS e.max CAD (IP), IPS Empress CAD (IE), Mark II (M) and Lava Ultimate (LU)) with A1 shade. Each group was divided into five subgroups ( n = 12) according to the control (C) and four different polishing system: Sof-Lex (S), Edenta (E), Identoflex (I) and Zircon Brite (Z). Surface roughnesses (Ra) were measured by a profilometer before and after polishing. The baseline colour values were recorded according to the CIELab system. The colour coordinates (L*, a* and b*) of the samples were measured before and after UV ageing, and colour differences (ΔE₀₀) were calculated by using the CIEDE2000 colour difference formula. A two-way ANOVA and Tukey test methods were used to analyse the data (α = 0.05). Results: A significant interaction was observed between CAD-CAM blocks and polishing system ( p < 0.001). The higher Ra and colour difference was calculated in LU in the Z group after polished and the lower Ra and colour difference was calculated in the IP in the S group after polished. For the IP group, the glazing procedure showed higher Ra and ΔE values with Z group than polished S system, whereas there is no statistical differences. Conclusion: It is concluded that polishing with the Sof-Lex system improves significantly smoothness and colour stability. However, there is no success in using the Zircon Brite polishing system.