Effect of Endocrown Restorations with Different CAD/CAM Materials: 3D Finite Element and Weibull Analyses

The aim of this study was to evaluate the effects of two endocrown designs and computer aided design/manufacturing (CAD/CAM) materials on stress distribution and failure probability of restorations applied to severely damaged endodontically treated maxillary first premolar tooth (MFP). Two types of designs without and with 3 mm intraradicular extensions, endocrown (E) and modified endocrown (ME), were modeled on a 3D Finite element (FE) model of the MFP. Vitablocks Mark II (VMII), Vita Enamic (VE), and Lava Ultimate (LU) CAD/CAM materials were used for each type of design. von Mises and maximum principle values were evaluated and the Weibull function was incorporated with FE analysis to calculate the long term failure probability. Regarding the stresses that occurred in enamel, for each group of material, ME restoration design transmitted less stress than endocrown. During normal occlusal function, the overall failure probability was minimum for ME with VMII. ME restoration design with VE was the best restorative option for premolar teeth with extensive loss of coronal structure under high occlusal loads. Therefore, ME design could be a favorable treatment option for MFPs with missing palatal cusp. Among the CAD/CAM materials tested, VMII and VE were found to be more tooth-friendly than LU

Basics of dentin-pulp tissue engineering

Regeneration is reconstruction of a tissue with the shape and function of the original tissue including vascularization and innervations. Highly degradation of dentin-pulp complex can not be reversed by its own repair mechanisms. For decades, endodontic treatments including pulpectomy and preparation of root canals have been the first choice for these cases. However, root canal treatment method has some unsatisfying consequences like; esthetic problems as a conclusion of discoloration caused by endodontic filling materials, undermined integrity of tooth structure, postoperative fractures, coronal leakage or periapical microleakage, lost sense of environmental changes which can make the recurrent caries or apical infection unnoticeable for patient and shortened lifetime in comparison with vital teeth. Currently regeneration of dentin-pulp complex by tissue engineering approach is thought to be a more appropriate choice instead of root canal treatment according to these outcomes. In this review, we will discuss basic components as stem cells, signaling molecules and scaffolds and also methods used for dentin-pulp tissue engineering

FARKLI POLİMERİZASYON ZAMANLARININ KONDANSE EDİLEBİLİR KOMPOZİT REZİNLERİN YÜZEY SERTLİĞİ ÜZERİNE ETKİLERİ

Bu çalışmanın amacı dört farklı kondanseedilebilir kompozitin 20 sn ve 40 sn ışık uygulamasısonucu oluşan alt ve üst yüzey sertlik değişiklerininincelenmesidir. Yüzey sertlik ölçümleri için dörtfarklı kondanse edilebilir kompozit P60, Surefil,Solitare 2 ve Pyramid-Dentin 2 mm kalınlığında ve8 mm çapında pleksi glass kalıp içerindeki boşluklara yerleştirildi n=20 . Polimerizasyonlar halojenbir ışık kaynağı kullanarak 600 mW/cm2 20 sn n=40 ve 40 sn n=40 olacak şekilde polimerize edilen örnekler, Knoop Hardness KHN testi ile yüzey sertlik değerleri ölçüldü. İstatistiksel değerlendirme tek yönlü varyans analizi ANOVA ile yap›ld› ve gruplar aras› farkl›klar Tukey testi ile belirlendi.En yüksek üst ve alt yüzey sertliği s›ras› ile P60> Surefil> Solitare 2 = Pyramid-Dentin olarak tespit edildi. Iş›k uygulama süresi 20 sn veya 40 sn Surefil kompozit d›ş›nda kompozitlerin birçoğunda üst yüzey sertlik değerlerini değiştirmedi. Sadece Surefil kompozit grubunda 40 sn polimerize edilen örnekler, 20 sn polimerizasyona göre daha fazla sertlik değeri gösterdi

FARKLI YÖNTEMLERLE HAZIRLANAN SINIF II KAVİTELERDE ESTETİK RESTORASYONLARIN MİKROSIZINTISININ DEĞERLENDİRİLMESİ

Bu çalışmanının amacı; farklı yöntemlerlehazırlanan Sınıf II kavitelere uygulanan çeşitlirestoratif materyallerin, iki farklı ışık ucu ilepolimerize edildikleri zaman mikrosızıntı performanslarının değerlendirilmesidir.Bu çalışmada 72 adet çürüksüz yeni çekilmişinsan molar dişi kullanılmıştır. Çekim sonrasında dişler üzerindeki yumuşak dokular ve art›klar bir kretuar, pomza ve f›rça yard›m›yla uzaklaşt›r›lm›şt›r. Dişler distile su içinde saklanm›şt›r. Her bir grupta 24 adet olacak şekilde dişler üç gruba ayr›lm›şlard›r. Grup 1’de Sonicsys Approx sistem Excite Bond, Tetric Flow, Tetric Ceram, Sonicsys Insert kullan›larak S›n›f II kaviteler haz›rlanm›ş, 12 örnek turbo ›ş›k ucu ile 12 örnek de geleneksel ›ş›k ucu ile polimerize edilmiştir. Grup 2’de kontrol haz›rlanan kaviteler ak›c› kompozit rezin kaide ve hibrit kompozit rezin Gluma Comfort Bond, Flow Line, Charisma ile Grup 3’de haz›rlanan kaviteler de ak›c› kompozit rezin kaide ve kondanse edilebilir kompozit rezin Gluma Comfort Bond, Flow Line, Solitaire 2 kullan›larak Grup 1’deki gibi polimerize edilmişlerdir. Örnekler 37ºC distile suda yedi gün etüvde bekletildikten sonra 5 ± 2ºC ve 55 ± 2ºC aras› ›s› banyolar›nda; her banyoda 10 s’lik transfer süresiyle bir siklus 30 s olacak şekilde 1000 kez termal siklus işlemine tabi tutulmuştur. Daha sonra örneklerin kök uçlar› kompozit rezinle kapat›lm›ş ve dişler iki kat aside dirençli cila ile restorasyon marjinlerinin 1 mm d›ş›nda kalacak şekilde kaplanm›şt›r. Tüm örnekler % 0,5’lik bazik fuksin solüsyonuna dald›r›larak 24 saat bekletilmiştir. Daha sonra dişlerin kron k›sm› aç›kta kalacak şekilde soğuk akrilik dikdörtgen bloklara dik olarak gömülmüş ve örnekler elmas bir kesici uca sahip "mikrocut" yard›m›yla su soğutmal› olarak mezio-distal olarak kesitlere ayr›lm›şt›r. Her restorasyon binoküler stereomikroskop alt›nda x20 büyütme ile incelenmiş ve skorlanm›şt›r.S›z›nt› değerlerini iki grupta karş›laşt›rmak için Mann-Whitney U testi, üç grupta karş›laşt›rmak için ise Kruskal Wallis non-parametrik varyans analiz testi kullan›lm›şt›r. Her grupta okluzal ve gingival kavite kenarlar›ndaki mikros›z›nt› değerleri karş›laşt›rmas›nda Wilcoxon Matched-Pairs Signed Rank testi kullan›lm›şt›r.

Effect of ethylenediamine tetraacetic acid and etidronic acid on the surface roughness of Biodentine: in vitro

Objective: The aim of this study was to evaluate the effect of 9% etidronic acid (HEBP) and 17% ethylenediamine tetraacetic acid (EDTA) on the surface roughness of Biodentine. Materials and Method: Biodentine (Septodont) was mixed according to the manufacturer’s instructions. Briefly, five drops of liquid were added into the capsule containing the powder. Then the capsule was placed in a triturator for 30 sec. The prepared mixture was placed into a mold (diameter: 5 mm, depth: 3 mm). The Biodentine surfaces were polished with silicon carbide abrasive papers. The surface roughness of 30 samples was measured at baseline using a portable surface roughness tester. For this purpose, a 5 mN force was applied onto three different locations of the samples with a speed of 0.8 mm/sec. The samples were divided into two groups according to the irrigation solution (n=15); first group was treated with 9% HEBP, and the second group was treated with 17% EDTA. The surface roughness of the samples was measured again after 1 and 2 min of irrigant application. Data were statistically analyzed using one-way ANOVA and independent sample t-test. Results: For HEBP, no significant difference was found between the surface roughness values at 0., 1., and 2 min (p=0.107; ANOVA). For EDTA, the surface roughness value at 1 min was significantly greater than the baseline value (p<0.001; t-test). The surface roughness changes at the two time periods were significantly different between the EDTA and HEBP groups (p=0.003 for 0-1 min passage, p=0.021 for 1-2 min passage). Conclusion: The use of 17% EDTA may result in deterioration of Biodentine’s surface during perforation repair and root canal treatment

Effect of Direct and Indirect Materials on Stress Distribution in Class II MOD Restorations: A 3D-Finite Element Analysis Study

The aim of this study is to investigate the stress distributions of different restoration options for class II mesio-occluso-distal (MOD) cavities. A class II MOD cavity with proximal box gingival floor 1 mm below cementoenamel junction was designed in a mandibular first molar tooth model. 3D finite-element analysis (FEA) and 3D-CAD modelling were used to examine the occlusal stresses distributed to the remaining buccal enamel (RBE), remaining lingual enamel (RLE), adhesive surfaces, and restorative materials by direct and indirect materials resulting from a 600 N of static occlusal load stimulating foodstuff. von Mises (VM) and maximum principal (Pmax) stresses were evaluated for two CAD/CAM materials and three direct materials. CAD/CAM materials exerted less stress than the direct restorative materials. Significant von Mises and Pmax stress value differences were seen among all restoration models on RBE. Reducing RLE and including it into the cavity would be a more effective option for this model in this scenario. As VM and Pmax stresses of PIHC CAD/CAM material for RBE and dentin were significantly lower than other tested materials, it may be the choice of material for indirect MOD restorations

Dislodgement resistance and structural changes of tricalcium silicate-based cements after exposure to different chelating agents.

This study aimed to evaluate the dislodgement resistance and structural changes of different mineral trioxide aggregate cements (MTA) like Pro-Root MTA, Ortho MTA, and Retro MTA after exposure to sodium hypochlorite (NaOCl), NaOCl-Ethylenediaminetetraacetic acid (EDTA), 1-hydroxyethylidene-1, 1-bisphosphonate (Dual Rinse HEDP), and NaOCl-Maleic acid (MA). The root canal spaces of 150 dentine slices were obturated using tricalcium silicate cements and divided into 3 groups (n = 50): Group1: ProRoot MTA, Group2: Retro MTA, and Group3: Ortho MTA. The samples in each group were further subdivided into four experimental (n = 10) and one control groups (n = 10): 2.5% NaOCl-17% EDTA, Dual Rinse HEDP, 2.5% NaOCl-7% Maleic acid, 2.5% NaOCl, distilled water (control). The dislodgement resistance and structural changes of cements were measured. Use of DR HEDP resulted in higher dislodgement resistance compared to17% EDTA and 7% MA in the samples obturated with Ortho MTA and Pro-Root MTA (p<0.001). In Retro MTA group, samples treated with DR HEDP and 17% EDTA had higher dislodgment resistance compared to 7% MA (p<0.001). On microstructural and elemental analysis of all the three MTA cements, samples treated with 17% EDTA and 7% MA were more amorphous and granular when compared to DR HEDP, which was pettle shaped. Calcium level was decreased more in samples treated with 17% EDTA and 7% MA when compared to DR HEDP

Farklı sistemlerle bitirme ve cila uygulanan üç kompozit rezinin yüzey pürüzlülüğü

Bu çalışmanın amacı; nano-dolduruculu bir kompozit Filtek Supreme XT , bir nano-seramik kompozit CeramX ve bir nano-hibrit kompozitin Grandio yüzey pürüzlülüğü üzerine iki farklı bitirme frezi ve iki farklı cila sisteminin etkisini araştırmaktır. Her kompozit rezin için paslanmaz çelik kalıplar kullanılarak disk şeklinde 5 mm çap-2 mm kalınlık 35 örnek hazırlandı. Örnekler bitirme ve cila prosedürlerine göre rastgele gruplara ayrıldı. Grup 1: Şeffaf bant control , Grup 2: Elmas bitirme frezleri, Grup 3: Elmas bitirme frezleri +Optidisc, Grup 4: Elmas bitirme frezleri +HiLuster, Grup 5: Tungsten karbit frez, Grup 6: Tungsten karbit frez +Optidisc, Grup 7: Tungsten karbit frez +Hi-Luster. Tüm örneklerin ortalama yüzey pürüzlülük değerleri Ra profilometre ile ölçüldü. Bulguların istatistiksel değerlendirmeleri