Evaluation of fracture strength of different CAD/CAM veneers that are manufactured for zirconia cores

Amaç. Bu çalışmanın amacı, farklı veneer materyalleri ve işlemleri ile hazırlanmış basit ve anatomik kor tasarımları kullanarak kaplanmış zirkonya altyapılı kronların kırılma direncini değerlendirmektir. Gereç ve Yöntemler. Anatomik bir çekirdek tasarımı veya basit bir çekirdek tasarımı ile toplam 100 zirkonya kron altyapısı üretildi. Bu kor altyapılar daha sonra aşağıdaki veneerleme prosedürlerine göre beş alt gruba ayrıldı: Kontrol (katmanlama), simante CAD/CAM fabrikasyon feldspatik veneer, simante CAD/CAM fabrikasyon lityum disilikat veneer, porselenle kaynaştırılmış CAD/CAM fabrikasyon feldspatik veneer ve porselenle kaynaştırılmış CAD/CAM fabrikasyon lityum disilikat kaplama. Daha sonra, bir çiğneme simülatöründe 1,6 Hz'de 50 N'luk bir oklüzal yük ile 250000 döngü uygulandı ve yükleme sırasında bir termal döngü uygulandı (her 60 saniyede bir 5°C ila 50°C). Kronlar daha sonra evrensel bir test makinesi kullanılarak kırma testine tabi tutuldu. Bulgular. Gruplar arasında istatistiksel analizler önemli farklılıklar gösterdi (F= 23.296;

FONKSİYONEL KUVVETLER ALTINDAKİ FARKLI LAMİNATE VENEER KRONLARIN SONLU ELEMANLAR STRES ANALİZ YÖNTEMİ İLE DEĞERLENDİRİLMESİ

Bu çalışmanın amacı; sonlu elemanlar stresanaliz yöntemi ile farklı preparasyonlar uygulanarak hazırlanan seramik ve kompozit laminateveneer kronlar üzerinde fonksiyonel kuvvetlerinoluşturduğu gerilimlerin nasıl dağılım gösterdiklerinin tespit edilmesidir. Bu amaçla maksiller santral kesici dişin periodontal dokularla birlikte doğal boyut veilişkilerini gösteren labio-lingual yönde iki boyutlukesiti oluşturulmuştur. Bu kesit esas alınarak dahasonra bir tanesi restorasyon uygulanmamış üstsantral kesici diş olmak üzere dokuz farklı durumuifâde eden matematiksel modeller hazırlanmıştır.Fonksiyon, ısırma anını gösteren kuvvet ile temsiledilip, vertikal ve horizontal bileşenden oluşturulmuştur. Bu kuvvetlerin uygulama noktası herdurum için sabit olacak şekilde insizal bölgedeseçilmiş ve toplam 200 N kuvvet uygulanmıştır.Oluşan gerilimleri inceleyebilmek için SAP 90analiz proğramı, sonuçları değerlendirebilmek içinde SAPLOT çizim proğramı kullanılmıştır. Sonuçlar, makaslama ve çekme-sıkışma gerilimleri olmak üzere iki grup altında değerlendirilmiştir. Yapılan analizler sonucunda; kompozit laminate veneer grubu için en yüksek gerilim değerilabial yüz ve insizal kenarı içine alan preprasyonlarda çekme gerilimi olarak tespit edilmiştir.Porselen laminate veneer kronlar için en yüksekgerilim değeri ise; rakamsal olarak daha düşükolmakla beraber yine kompozit laminate veneergrubunda olduğu gibi labial yüz ve insizal kenarıiçine alan preparasyon tasarımında çekme gerilimiolarak tespit edilmiştir. Bu çalışma sonucundaporselen materyal üzerinde ve mine - restorasyonhudutunda çok fazla gerilim yoğunluğununoluşmaması laminate veneer kronları güvenli birşekilde kullanabileceğimizi ifâde etmektedir. Özellikle tüm veriler değerlendirildiğinde gerilimdağılımı açısından en uygun restorasyon tipinindişin doğal boyutu korunarak sadece labial yüzdepreparasyon yapılarak hazırlanan laminate veneeruygulaması olduğu sonucuna varılmıştı

Assessment of dental care during the covid-19 pandemic in Turkey and future projections

A new coronavirus disease has affected the whole world, starting from Wuhan, China at the end of 2019. The disease, caused by the pathogen of SARS-CoV-2, commonly called COVID-19, has soon passed into the history of epidemics as the most effective pandemic recently. Dentistry has also been significantly affected by the pandemic process, which had a restrictive effect on almost all aspects of social life. Dental treatments are healthcare services that have been applied very carefully in terms of the risk control of cross-infection prior to this pandemic where disinfection and sterilization rules continue to be controlled at the highest level. However, hand instruments used in most dental treatments and generating aerosol has raised concerns, particularly in diseases such as COVID-19, which increase the risk of droplet contamination. This working order is an important risk factor not only for healthcare professionals but also for the contamination of patients and the environment. In addition, the continuing pandemic process and the dynamics of the process require revision of the protocols. For this reason, each country has prepared protocols in order to maintain the dental treatments in the pandemic process in accordance with their own health care conditions and policies.This process caused the dental professionals to reconsider their routine working practices and prospectively, new protocols are recommended for dental applications. This article aims to provide a perspective evaluating the current situation and discuss additional measures to be considered during the pandemic and thereafter. KEYWORDSCoronavirus; SARS-CoV-2; COVID-19 Pandemic; Dentistry; Infection Control, Transmission

Effect of endodontic access simulation on the fracture strength of lithium-disilicate and resin-matrix ceramic CAD-CAM crowns

OBJECTIVES The purpose of this in vitro study was to compare the effect of simulated endodontic access preparation on the failure loads of lithium disilicate crowns and resin-matrix ceramic (RMC) crowns. MATERIALS AND METHODS Eighty maxillary first premolar crowns were manufactured by using four different CAD/CAM blocks (n = 20): lithium disilicate (LD; IPS e.max CAD), resin nanoceramic (RNC; Lava Ultimate), flexible nanaoceramic (FNC; GC Cerasmart), and polymer-infiltrated ceramic (PIC; VITA Enamic). Half of each group was accessed and repaired to simulate endodontic treatment. After cyclic loading, all specimens were loaded to failure. Data were analyzed with two-way ANOVA followed by Tukey-HSD test (α = .05). RESULTS The load to failure results showed significant differences for material types (P < .001), but not for endodontic access simulation (P = .09). The highest and lowest mean failure loads were obtained for LD (1546 N) and PIC (843 N), respectively. CONCLUSION The endodontic access preparation was not found to affect the fracture strength of LD and RMC crowns. The LD showed higher fracture strength than RMC crowns. Even though significant differences were noted for failure loads regarding different crown materials, all could reasonably withstand masticatory forces. CLINICAL SIGNIFICANCE The endodontic access preparation through a restoration is known to be a common challenge in clinical practice. Maintaining a repaired LD or RMC crown is feasible and replacement may not be necessary

Full-mouth reconstruction with Implant and Tooth-supported Zirconia Restorations in a Digital Workflow

Zirconia has become a popular restorative material regarding the mechanical and biocompatibility advantages. Monolithic and translucent forms of zirconia advanced the aesthetics of this material, making it the material of choice for both tooth- and implant- supported restorations. Also, digital fabrication of zirconia not only enables accurate restorations but also provides time efficiency. The present case report demonstrates the rehabilitation of a patient who has generalized tooth wear with implant- and tooth-supported monolithic zirconia restorations with buccal veneers in a newly established occlusal vertical dimension. The treatment process was completed in a digital workflow as the impressions were taken with a powder-free intraoral scanner and the digital data were send to the dental laboratory to fabricate the restorations. Monolithic zirconia restorations with buccal feldspathic veneers were completed without any adjustments in only two appointments. The patient was satisfied and the restorations have been in service for two years

Correlates of anxiety and depression in Turkish complete denture patients

Denture wearing is a stressful life event which can cause Anxiety and depression. Patients' adaptation to dentures may be hindered by their emotional reactions. The present study examined the variables related to anxiety and depression symptoms among 158 adult complete dental prosthesis patients. The results showed that the participants had mild to moderate depression and moderate state anxiety symptoms. The results of the regression analyses showed that treatment duration, perceived burden due to teeth loss and expected benefits of new dentures were related to anxiety. Age, burden of teeth loss and perceived social support from the dentist were related to depression symptoms. Therefore, these variables need to be considered in the management of prosthesis patients

Comparison of Stain Effects of Nicotine and Beverages on Different Cad-Cam Materials

Purpose: This study aimed to compare the effect of smoking cigarettes and drinking beverages and also polishing procedures on the discoloration of CAD/CAM materials. Materials and Methods: Resin nanoceramic (Lava Ultimate-RN), feldspar ceramic (CEREC Blocs Ceramics-FC) and lithium disilicate glass-ceramic (IPS e.max® CAD-LDC) specimens (5X5 X2 mm) were used for this study. Initially, baseline surface roughness (Ra) and color values (L*, a*, b*) of the specimens were measured with profilometer and chroma meter. Then the specimens were exposure nicotine, coffee and red wine. The first discoloration values of each specimen were measured. Then, all of the specimens were subjected to re-polishing procedures. Than, the surface roughness and color values of each specimen were measured. The specimens were subjected to the same staining process again. After exposure of the specimens to the staining agents, the second staining value was measured. Two-way analysis of variance (ANOVA) was used for normally distributed groups, and the Kruskal-Wallis test was used for non-normally distributed groups. Results: Statistically significant ΔE* values were observed for RN (8.26±1.55) and FC (7.69±1.52) for nicotine in the first staining group. The maximum total color changes were observed in the nicotine group for all of the material specimens. Nicotine caused the highest color changes on the test materials than coffee and wine. Surface roughness did not show a statistically significant difference based on the staining agents for any of the materials within a group (p lt;0.05). Conclusions: It was observed that nicotine staining is far stronger than beverage staining

FARKLI SERAMİK KOR YAPILARININ VENEER PORSELEN RENGİ ÜZERİNE ETKİLERİNİN DEĞERLENDİRİLMESİ

Giriş: Günümüzde restoratif materyallerin gelişimindeki hızlı ilerlemeler diş hekimliğinde çok çeşitli materyallerin kullanımına izin vermektedir. Dental materyal teknolojisinin gelişmesiyle estetik restorasyonlara talebin artması birçok uygulamada tam seramik restorasyonların kullanılmasına sebep olmaktadır. Tam seramiklerin doğal dişlerle uyum kabiliyeti, yüksek fiziksel ve optik özelliklerinden dolayı seramikler yüksek estetik beklentili hastalar için tercih edilmektedir. Yaptığımız in vitro çalışmanın amacı; CIE’nin belirlediği formülasyona göre farklı kor yapılarının final restorasyon rengine etkilerini karşılaştırmak ve bu renklerin farkedilebilirliğini incelemektir. Materyal ve Metod: Kor yapısını taklit etmek amacıyla kare formda 5 × 5 × 1,5 hazırlanmış zirkonyum oksit Y-TZP içerikli Cercon ve lityum disilikat içerikli IPS Empress 2 materyalleri kullanılmıştır. A1 skala renginde Cercon Ceram S ve d.Sign seramikleri; kor yapılar üzerine yığılmış, tüm örneklerin rengi kromametre ile ölçülmüştür. Örneklerin hepsi CIELAB sistemi tarafından kabul edilen kırmızı x , yeşil y ve mavi z 3 rengin isimlendirildiği tristimulus koordinatlarının baz alındığı CIELAB formülünce değerlendirilmiştir. Renk değişimlerinin değerlendirilmesinde CIELAB sisteminin tercih edilme sebebi minimum renk farklılıklarının ölçümündeki hassasiyettir. Bulgu: Her bir grupta L*, a*, b* verileri için ortalama ve standart sapma hesaplanmıştır. Sonuçlar; iki farklı seramik grubundaki renk farklılığının ΔE renk eşleştirmesinde aynı algılanılmasından öte olduğunu göstermektedir. Lityum disilikat örneklerin IPS Empress 2, ∆E: 4,97 renk değişikliği klinik uygulamalarda belirgin farklılığı ifade etmektedir. Zirkonyum oksit Cercon, ΔE: 1,99 içerikli örnekler ise algılanabilir renk farklılığına sahiptir. Sonuç: Dental klinisyenlerin en önemli handikaplarından birisi laboratuvarda üretilmiş restorasyon rengi ile seçilen renk arasında uyumsuzluk olarak bilinmektedir. Estetik olarak daha iyi sonuçlar elde edilebileceği düşünülen yüksek translüsensli seramik materyallerin çevresel etkilerden daha fazla etkilenip daha fazla renk farklılığı gösterebileceği göz önünde bulundurulmalıdı

Influence Of Nano Alumina Coating On The Flexural Bond Strength Between Zirconia And Resin Cement

PURPOSE The purpose of this in vitro study is to examine the effects of a nano-structured alumina coating on the adhesion between resin cements and zirconia ceramics using a four-point bending test. MATERIALS AND METHODS 100 pairs of zirconium bar specimens were prepared with dimensions of 25 mm × 2 mm × 5 mm and cementation surfaces of 5 mm × 2 mm. The samples were divided into 5 groups of 20 pairs each. The groups are as follows: Group I (C) – Control with no surface modification, Group II (APA) – airborne-particle-abrasion with 110 µm high-purity aluminum oxide (Al2O3) particles, Group III (ROC) – airborne-particle-abrasion with 110 µm silica modified aluminum oxide (Al2O3 + SiO2) particles, Group IV (TCS) – tribochemical silica coated with Al2O3 particles, and Group V (AlC) – nano alumina coating. The surface modifications were assessed on two samples selected from each group by atomic force microscopy and scanning electron microscopy. The samples were cemented with two different self-adhesive resin cements. The bending bond strength was evaluated by mechanical testing. RESULTS According to the ANOVA results, surface treatments, different cement types, and their interactions were statistically significant (P<.05). The highest flexural bond strengths were obtained in nanostructured alumina coated zirconia surfaces (50.4 MPa) and the lowest values were obtained in the control group (12.00 MPa), both of which were cemented using a self-adhesive resin cement. CONCLUSION The surface modifications tested in the current study affected the surface roughness and flexural bond strength of zirconia. The nano alumina coating method significantly increased the flexural bond strength of zirconia ceramics.PubMedWo