Onur Şahin

The clinical performance of interim restorations, particularly in the anterior region, largely depends on surface roughness (Ra) and color stability. This study investigated the influence of different toothbrushing durations on the surface roughness and color stability of CAD/CAM interim restorative materials subjected to varying polishing protocols. A total of 140 rectangular specimens (15 × 9 × 2 mm) were fabricated from highly cross-linked PMMA blocks (Telio-CAD, Ivoclar Vivadent, Schaan, Liechtenstein) and allocated to two surface treatment groups: conventional polishing and surface coating with Optiglaze Color (GC Corp, Tokyo, Japan). Each group was further divided into seven subgroups (n = 10), including a control (no brushing) and groups that performed simulated brushing (DentArge TB-6.1, Analitik Medikal, Gaziantep, Turkiye) with distilled water or toothpaste (Colgate Total; Colgate-Palmolive, New York, NY, USA), for 2 weeks, 3 months, or 1 year. Ra values were recorded before (Ra0) and after brushing (Ra1), and color changes (ΔE₀₀) following immersion in coffee solution were calculated. Statistical analysis was performed using a three-way ANOVA and Tukey’s HSD test (α = 0.05). Specimens coated with Optiglaze Color exhibited significantly lower Ra values compared with conventionally polished specimens (p < 0.05). The Con_Tp_1Yr group demonstrated the highest Ra value (0.53 ± 0.08 µm) compared to all other specimen groups (p < 0.05). A one-year brushing duration markedly increased ΔE₀₀ values in both surface treatment groups regardless of brushing medium (p < 0.05). While surface coating was more effective than conventional polishing in obtaining smoother surfaces at all brushing durations, prolonged brushing with toothpaste produced a progressive increase in surface roughness in both treatments. Ra values increased consistently over time, with the most pronounced changes observed after one year of brushing. Within the limitations of using a single CAD/CAM material, it may be concluded that surface coating improves the initial smoothness of interim crowns; however, extended brushing and different brushing media can intensify color changes, indicating that the long-term stability of surface-coated interim restorations may be compromised under abrasive conditions.

This study aimed to compare the effect of acid etching, sandblasting, or silica coating on the micro-shear bond strength of dual-cured resin cements to computer-aided design and computer-aided manufacturing (CAD/CAM) glass ceramic materials. Feldspathic, lithium disilicate, and zirconia-reinforced CAD/CAM ceramics were divided into four groups: control group (C), no surface treatment; hydrofluoric (HF) group, 5% HF acid-etched; sandblasting (SB) group, abraded with 50 µm aluminum oxide (Al₂O₃) particles; silica-coated (CJ) group, abraded with 30 µm silica-modified Al₂O₃ particles. Roughness values were obtained by using a profilometer. The cements were condensed on the surface-treated specimens and a micro-shear bond test was conducted. The ceramic material (p < 0.001) and surface treatment type (p < 0.001) significantly affected the micro-shear bond strength values. HF acid etching can be recommended for the surface pretreatment of feldspathic, lithium disilicate, and zirconia-reinforced CAD/CAM ceramics. Better bond strengths can be obtained with HF acid etching than with sandblasting and silica coating.

The surface properties and color stability of interim crown materials may vary depending on the toothbrushing procedure. This study aimed to investigate the effects of toothbrushing and different toothpastes on the surface roughness (R_a) and color stability of different interim crown materials. Disc-shaped specimens were prepared from four interim crown materials (Tab 2000 (ChPM), Imident (LaPM), Protemp 4 (ChDM), and Telio-CAD (CadPM)). Specimens were divided into four subgroups for the control group (Cnt) and for simulated toothbrushing with distilled water (Dw) or with two different toothpastes (whitening toothpaste (WTp), activated charcoal toothpaste (ACTp)). The specimens’ R_a values were measured before and after 10,000 cycles of toothbrushing. The color parameters were measured and the color differences (ΔE₀₀) were calculated. Data were statistically analyzed by two-way analysis of variance (ANOVA) and Tukey’s HSD tests. A significant increase in the R_a values was observed after toothbrushing, except for the LaPM_Dw, ChDM_Dw, and all the CadPM specimens (p < 0.05). Toothbrushing with toothpastes increased the ΔE₀₀ values of all ChPM and ChDM interim materials (p < 0.05). Before and after all toothbrushing procedures, the CadPM specimens had smoother and ChPM specimens had rougher surfaces than the other interim materials. The two tested toothpastes had similar effects on the R_a of all interim materials. Non-perceivable color changes were seen only with the CadPM_Dw group.

Background: With the application of surface sealant agents, smooth surfaces can be achieved in a shorter time when compared with conventional polishing. However, studies on the performance of these agents against chewing forces are not many. The purpose of this study was to evaluate the surface roughness and Streptococcus mutans adhesion on surface sealent coupled interim prosthetic materials after chewing simulation. Methods: One hundred and twelve specimens were fabricated from two poly(methyl methacrylate) (Tab 2000, Dentalon Plus) and two bis-acryl (Tempofit, Protemp 4) interim crown materials and divided into 4 groups (n = 7) according to applied surface treatment: conventional polishing (control) and 3 surface sealant (Palaseal, Optiglaze, Biscover) coupling methods. The surface roughness values (R_a) were measured with a profilometer before (Ra0) and after aging through dynamic loading in a multifunctional chewing simulator for 10,000 cycles at 50 N load combined with integral thermocycling (between 5 and 55 °C) (Ra1). Specimens were incubated with Streptococcus mutans suspension and the total number of adherent bacteria was calculated by multiplying the counted bacterial colonies with the dilution coefficient. Results: Surface sealant agent application significantly decreased the surface roughness compared with conventionally polished specimens, except for Optiglaze or BisCover LV applied Protemp 4 and Palaseal or Biscover LV applied Tempofit. Surface roughness after dynamic loading showed a statistically significant increase in all groups, except for the control groups of Tab 2000 and Protemp 4. A positive correlation was found between surface roughness values of interim prosthodontic materials and the quantitiy of Streptococcus Mutans. Conclusions: Even though surface sealant agent application significantly decreased the surface roughness compared with conventionally polished specimens, dynamic loading significantly increased the surface roughness of all surface sealant coupled materials. The R_a values of all test groups were higher than the plaque accumulation threshold (0.20 µm). Streptococcus mutans adhered more on rougher surfaces.

Background: Surface sealant agents have been developed as an alternative to conventional polishing methods. These agents can achieve smoother surfaces in less time than conventional methods, studies on the condition of these agents against the chewing forces are lacking. The purpose of this study is to evaluate the surface roughness and the adhesion of Streptococcus mutans adhesion after chewing simulation of surface sealent coupled interim prosthetic materials.Methods: One hundred and twelve specimens were fabricated from two poly(methyl methacrylate) (Tab 2000, Dentalon Plus) and two bis-acryl (Tempofit, Protemp 4) interim crown materials and divided into 4 groups (n=7) according to applied surface treatment procedures: conventional polishing (control) and 3 surface sealant (Palaseal, Optiglaze, Biscover) coupling methods. The surface roughness values were measured with a profilometer before (Ra0) and after aging process through dynamic loading in a multifunctional chewing simulator for 10,000 cycles at 50 N load combined with integral thermocycling (between 5°C and 55°C) (Ra1). Specimens were incubated with Streptococcus mutans suspension and bacterial colonizations were evaluated.Results: Except the use of Optiglaze and BisCover LV surface sealant agents on Protemp 4 and the use of Palaseal and Biscover LV on Tempofit; surface sealant agent application significantly decreased the surface roughness compared with the conventionally polished specimens. Statistically, surface roughness after dynamic loading showed a significant increase in all groups, except Tab 2000 and Protemp 4 control groups. A positive correlation was found between surface roughness values of interim prosthodontic materials and the quantitiy of Streptococcus Mutans. Conclusions: Even though surface sealant agent application significantly decreased the surface roughness compared with the conventionally polished specimens, dynamic loading significantly increased the surface roughness of all surface sealant coupled groups. The Ra values of all test groups were higher than the plaque accumulation threshold (0.20 µm). Streptococcus mutans adhered more on rougher surfaces.

Objective: To investigate the effect of toothbrushing on the surface roughness (R_a) of different sealant agent coupled nanohybrid composite resins.Materials and Methods: One hundred sixty disc‐shaped (10 × 2 mm) specimens were prepared from four different nanohybrid composite resins (Z‐550, Tetric EvoCeram, Clearfill Majesty, Ice). Specimen groups were divided into four subgroups for conventional polishing (control) and to apply three different surface sealant agents (Palaseal, Optiglaze, Biscover LV) (n = 10). The R_a values of the specimens were recorded before (R_a0) and after 10,000 cycles of toothbrushing (R_a1). The surface properties of the specimens were evaluated with scanning electron microscope (SEM). Data were statistically analyzed by two‐way analysis of variance (ANOVA), Tukey HSD, and paired sample t tests.Results: Composite resin material, surface treatment, and their interaction were significant on R_a values (p < 0.001). Significant decrease in R_a0 values observed for surface sealant agent coupled Clearfill Majesty and Tetric EvoCeram composite resin groups compared with the control groups (p < 0.05). After simulated one‐year toothbrushing, the control group of Clearfill Majesty had the highest R_a1 value (p < 0.001). The R_a1 values of all groups were significantly higher than the R_a0 values (p < 0.05).Conclusions: Simulated 1‐year toothbrushing increased the surface roughness of all nanohybrid composite resin materials. Optiglaze and Biscover LV sealant agents on Tetric EvoCeram, and all tested sealant agents on Clearfill Majesty enabled smoother surfaces than conventional polishing after toothbrushing.Clinical Significance: Because toothbrushing increases the surface roughness of tested nanohybrid composite resins, the application of surface sealant agents on some of the tested resins can be considered for smoother surfaces.

Objective: The aim of this study is evaluate the consistency of certain measurable dentolabial criteria between the esthetic values accepted in the literature and the subjective opinions of physicians. Materials and Methods: Four associated professors and four research assistants in the field of Prosthodontics were selected as the examiners of the study. Smile photos taken from 200 volunteer participants with only the mouth region were examined. The results of measurement of the curvature of the incisal edge and lower lip parallelism, incisal edge and lower lip contact, laugh line, buccal corridor and interincisal line and midline variables and subjective assessments of the evaluators were compared with Cochran Q test. Results: Esthetic perception is subjective and there was a significant correlation between objective measurements and subjective perception in the incisal edge and lower lip parallelism, laugh line and buccal corridor variables. No statistically significant difference was found between male and female individuals, similarly between specialists and research assistants. Conclusion: There is no consensus between esthetically objective findings and subjective views.

Herein, we report a study of novel hexachlorocyclotriphosphazene (N₃P₃Cl₆) derivatives bearing ethyl p-hydroxy benzoate and pendant ferrocenyl groups. Characterizations of the products [mono- 2, di- (geminal 3a; non-geminal trans^a-3b, trans^b-3c and cis-3d), tri- 4 and tetra- 5 substitue phosphazene derivatives] were performed using elemental analysis and spectral methods . The structure of the two compounds (2 and 5) are elucidated by X-ray diffraction techniques.