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    Effect of magnification and press-on force on resin composite polishing
    (BioMed Central, 2025) Ünal, Tuna; Korkut, Bora; Tağtekin, Dilek
    Objective To evaluate surface roughness (Ra) and gloss (GU) of two resin composites after polishing with two systems, using a novel press-on force guided (PFG) polishing simulator. Materials and methods Eighty specimens were prepared using Essentia Universal (EU) and G-aenial Universal Injectable (GUI) composites. Surface roughness and gloss were assessed by a profilometer (Marsurf Ps10), and a glossmeter (Novo-Curve). They were polished with Sof-Lex and Twist Dia systems with or without magnification and PFG. Each polishing material was used for 30 s. Ra1 and GU1 measurements were repeated by the same operator. Data were analyzed using One-way ANOVA, Three-way ANOVA, and Robust ANOVA with Bonferroni Correction for multiple comparisons and Spearman’s rho Correlation Coefficient (<0.050). Results Higher Ra values were observed in GUI group for Twist Dia (0.33±0.05z ) compared to SofLex (0.22±0.08y ). Roughness was higher when PFG was uncontrolled (0.31±0.07x ), compared to the controlled (0.25±0.09w). No Ra difference was observed in EU group between SofLex (0.33±0.04) and Twist Dia (0.29±0.04)(P=.440). Uncontrolled PFG provided higher gloss for GUI and EU composites (69.7±2.91x , 54.63±18.68x , respectively). Twist Dia presented higher gloss for GUI and EU composites (72.3±2.57z ,58.88±13.73z , respectively). Magnification did not affect the roughness or gloss for both composites (P≥.05). A moderate negative correlation was found between roughness and gloss in GUI (r=-.546)(P<.001), while no correlation was observed in EU (r=-.110)(P=.449). Conclusion Higher surface roughness and gloss were observed with uncontrolled (not constant) press-on force. Even though SofLex may provide a lower surface roughness, Twist Dia can generate a greater surface gloss regardless of the composite type. 3.5X loupe magnification was not effective on surface roughness and gloss within a limited polishing time. Clinical Relevance Press-on force is an important factor affecting the composite polishing quality. Spiral polishing wheels can be advantageous for composite restoration polishing, as they better preserve the secondary and tertiary anatomies and provide a higher gloss. The effect of magnification on composite polishing can be related to the time spent using it.
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    Evaluation of enamel surface roughness and volumetric change after resin remnant removal following orthodontic bracket debonding
    (Quintessence Publishing Deutschland, 2025) Korkut, Bora; Uzun, Kadir Emre; Hacıali, Çiğdem; Ünal, Tuna; Tağtekin, Dilek
    Purpose: To evaluate surface roughness and volumetric change of enamel after using different resin remnant removal (RRR) techniques, following orthodontic bracket debonding. Materials and Methods: Metal orthodontic brackets (Mini Twin Brackets, RMO) were bonded to 60 human (central or lateral) labial mid-third surfaces, and debonded 24 h after by a single orthodontist. The remaining composites were completely removed with the fluorescence light guidance by the D-Light-Pro led curing unit (GC/detection mode). The removal procedures were performed without magnification (n = 30) or with 20× magnification/5500 K illumination by a dental microscope (OMS2000, Zumax) (n = 30). Three RRR techniques were used: 12-bladed carbide bur (Horico), red-banded diamond bur (Horico), SofLex Disc (medium/40 μm, fine/24 μm, and superfine/8 µm; 3M). Surface changes were evaluated visually through microscope photographs by enamel surface index (ESI) and volumetrically by overlapping the three-dimensional images of a laser scanner device (LAS-20, SD-Mechatronik) in the Geomagic Design X (3D Systems) software. The deemed significance was set at 0.050 for the statistical analyses. Results: A positive, strong correlation was found between visual and volumetric change scores (P 0.001). Lesser volumetric loss (P 0.001) and roughness (P = 0.009) were observed for all RRR techniques when the magnification was used. Volumetric loss (mm3) by diamond bur was significantly the highest [1.85(1–3)a], followed by SofLex Disc [1.1(1–1)c] and carbide bur [0.59(0–1)b](P 0.001). Visual surface roughness scores (Ra) were significantly higher for diamond bur [4.5(4–5)b](P 0.001), followed by carbide bur 2(1–3)a and SofLex Disc 1(1–2)a. Conclusion: Surface roughness should always be assessed together with the volumetric enamel loss for the selection of RRR technique. Red-banded diamond bur should not be used for RRR. Even though the least surface roughness can be provided by SofLex Disc system, it can provide more intact enamel surface loss than the carbide bur. Magnification was considered useful for the RRR to provide a smoother surface while better preserving the intact enamel tissue.
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    Impact of lightness differences in digitally simulated composite resin restorations on perceived smile attractiveness
    (Wiley, 2025) Ntovas, Panagiotis; Ünal, Tuna; Korkut, Bora; Ferraris, Federico; Fehmer, Vincent; Sailer, Irena
    Objectives: To investigate the effect of lightness differences between digitally simulated composite restorations and anterior maxillary teeth, in combination with restoration type, and clinical experience on perceived smile attractiveness. Materials and Methods: An imaging software program (Adobe Photoshop CC 2023) was used to digitally manipulate a frontal full-face portrait of a smiling female model, to create five types of moderate-sized composite resin restorations of moderate size. For each restoration 14 lightness differences were simulated. The image was digitally modified to simulate five different types of composite resin restorations (Class III, Class IV, Class V, diastema closure (bilateral and unilateral approach)). Each restoration was adjusted through 7 incremental increases and 7 incremental decreases of 1 unit in lightness (L* value), yielding a total of 70 images. The smile attractiveness of each picture was rated by 80 dentists and 80 laypersons, ranged from 21 to 77years using a visual analog scale. The Wilcoxon signed-rank test was employed to assess whether the mean of a sample significantly differed from the control (p<0.05). Results: Among the different restoration types, crown fracture repairs (Class IV) had the greatest negative impact, followed by proximal restorations (Class III), diastema closures (Bilateral approach), diastema closures (Unilateral approach), and, lastly, cervical restorations (Class V), which had the least impact on perceived smile attractiveness (p≤0.05). The influence of lightness differences, whether toward a darker or lighter restoration, was dependent on both the type of restoration and the observer's experience. Conclusions: The effect of lightness difference on perceived smile attractiveness was significantly influenced by both the type of composite resin restoration and the observer's experience. Dental professionals perceived lightness discrepancies as less attrac tive compared to laypersons, suggesting that experience plays a key role in the perception of esthetic outcomes. Clinical Significance: The repositioning of an esthetic direct dental restoration is highly influenced by the dentist's chromatic perception which is more sensitive than that of a layperson who evaluates its matching with the natural tooth. The findings of the present study can support evidence-based clinical decision-making.