Effects of surface finishing procedures on the color, gloss, and surface roughness of CAD/CAM ceramics after coffee aging: an in vitro study surface finishing effects on CAD/CAM ceramics

Abstract

Aims: This in vitro study aimed to evaluate the effects of different surface finishing procedures-mechanical polishing, glazing, and polishing followed by glazing-on the color stability, surface roughness, and gloss of three CAD/CAM ceramic materials [feldspathic glass ceramic (GC), lithium disilicate (LDS), and zirconia-reinforced lithium silicate (ZLS)] after aging in a coffee solution. Methods: A total of 108 rectangular ceramic specimens (n=36 per material) were prepared in accordance with ISO 6872. Each material was divided into three subgroups based on the surface finishing procedure: mechanical polishing, glazing, and polishing+glazing. Baseline measurements of surface roughness (Ra), gloss (GU), and color (CIEDE2000, ΔE₀₀) were recorded. Specimens were aged in a coffee solution at 37 °C, and measurements were repeated at 1 week, 2 weeks, 1 month, and 2 months. At the end of the 2-month period, all specimens were re-polished and final measurements were obtained. Data were analyzed to determine material-, time-, and procedure-dependent differences. Results: Surface finishing protocols significantly affected all evaluated parameters (p < 0.05). Mechanical polishing produced the lowest Ra values (0.19±0.05 µm), while glazing alone resulted in the highest Ra after aging. The greatest increase in Ra was observed in zirconia-reinforced lithium silicate, whereas LDS maintained the lowest values throughout the study. The polishing+glazing protocol exhibited the highest GU (76.24±9.19 GU). LDS ceramic demonstrated the best GU retention, while ZLS showed the most pronounced loss over time. Both material type and finishing method significantly influenced ΔE₀₀ (p<0.001). The greatest discoloration was detected in polished ZLS (ΔE₀₀ up to 2.62), whereas LDS treated with polishing+glazing showed the lowest color differences (ΔE₀₀≈0.44 at early intervals). Post-aging repolishing reduced surface Ra below the clinically relevant threshold of 0.2 µm for all materials and improved gloss, indicating its value for long-term esthetic and periodontal maintenance. Conclusion: This study demonstrates that the long-term behaviour of CAD/CAM ceramics is shaped not only by material chemistry but also by the selected surface finishing strategy. The superior performance of the polishing+glazing protocol and the consistent benefits of repolishing for maintaining surface integrity is essential for esthetics, stain resistance, and periodontal tissue compatibility. These findings emphasized that appropriate material–surface protocol combinations, supported by periodic maintenance, is critical to achieving durable and biologically favorable ceramic restorations.

Keywords

• Computer-aided design
• coloring agents
• dental materials
• dental plaque
• surface properties
• materials testing

Kahve ile yaşlandırma sonrasında CAD/CAM seramiklerinin renk, parlaklık ve yüzey pürüzlülüğü üzerine yüzey bitirme işlemlerinin etkileri: in vitro çalışma

Abstract

Amaç: Bu in vitro çalışmanın amacı, farklı yüzey bitirme işlemlerinin (mekanik polisaj, glaze ve polisaj + glaze) üç farklı CAD/CAM seramik materyalinin [feldspatik cam seramik (GC), lityum disilikat (LDS) ve zirkonya ile güçlendirilmiş lityum silikat (ZLS)] renk stabilitesi, yüzey pürüzlülüğü ve parlaklığı üzerindeki etkilerini kahve ile yaşlandırma sonrası değerlendirmektir. Yöntem: ISO 6872 standardına uygun olarak her bir materyalden 36 adet olmak üzere toplam 108 dikdörtgen seramik örnek hazırlandı. Örnekler uygulanan yüzey bitirme işlemine göre üç alt gruba ayrıldı. Başlangıçta yüzey pürüzlülüğü (Ra), parlaklık (GU) ve renk değişimi (CIEDE2000, ΔE₀₀) ölçüldü. Örnekler 37 °C’de kahve solüsyonunda yaşlandırıldı ve ölçümler 1. hafta, 2. hafta, 1. ay ve 2. ayda tekrarlandı. İki aylık yaşlandırma sonunda tüm örneklere yeniden polisaj uygulanarak son ölçümler kaydedildi. Materyal, zaman ve yüzey işlemine bağlı farklılıklar istatistiksel olarak analiz edildi. Bulgular: Yüzey bitirme işlemleri tüm parametreleri anlamlı şekilde etkiledi (p < 0.05). Mekanik polisaj en düşük Ra değerlerini oluştururken, yalnızca glaze uygulanan gruplarda yaşlandırma sonrası en yüksek pürüzlülük görüldü. En belirgin pürüzlülük artışı ZLS grubunda, en düşük değerler ise çalışma boyunca LDS grubunda izlendi. Polisaj + glaze uygulaması en yüksek parlaklık değerlerini sağladı (76.24 ± 9.19 GU). LDS seramiği parlaklık açısından en stabil materyal olurken, ZLS zamanla en fazla parlaklık kaybını gösterdi. Renk değişimi açısından, materyal tipi ve yüzey işlemi ΔE₀₀ değerlerini anlamlı şekilde etkiledi (p < 0.001). En yüksek renk değişimi polisaj uygulanmış ZLS’de görülürken, polisaj + glaze uygulanan LDS grubu en düşük ΔE₀₀ değerlerini sergiledi. Yaşlandırma sonrası uygulanan yeniden polisaj işlemi, tüm materyallerde pürüzlülük değerlerini klinik olarak kabul edilen 0.2 µm eşik değerinin altına düşürdü ve parlaklığı artırdı. Sonuç: Bu çalışma, CAD/CAM seramiklerinin uzun dönem davranışlarının yalnızca materyal yapısı ile değil, uygulanan yüzey bitirme protokolüyle de yakından ilişkili olduğunu göstermektedir. Polisaj + glaze protokolü tüm estetik parametrelerde en dengeli sonuçları sağlarken, yaşlandırma sonrası yeniden polisaj yüzey bütünlüğünün korunmasında önemli katkı sunmuştur. Bu nedenle, uygun materyal–yüzey bitirme kombinasyonlarının seçilmesi ve periyodik bakımın sağlanması, uzun ömürlü ve biyolojik açıdan uyumlu seramik restorasyonlar için kritik öneme sahiptir.

Keywords

• CAD/CAM
• Renklendirici Ajanlar
• Dental Materyaller
• Dental Plak
• Yüzey Özellikleri

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