İhsan Yikilgan

How Can Stress Be Controlled in Endodontically Treated Teeth? A 3D Finite Element Analysis

The aim of this study was to analyze the stresses that develop by oblique and vertical forces in endodontically treated maxillary second premolars that were restored with resin composite. Additionally, in our study the effects of the different restorative approaches and use of different base materials on stress formation were analyzed using three-dimensional finite element stress analysis. For restoration, the models representing both cusp capping, palatinal cusp capping, standard MOD restoration, and use of woven fiber in occlusal part were prepared. In all models, oblique forces caused more stress than did vertical forces. Materials with low elastic moduli cause high amounts of stress, whereas materials with elastic moduli similar to that of dental tissues cause low amounts of stress. Additional approaches such as cusp capping, functional cusp capping, and woven fiber use do not affect stress formation on the tooth after endodontic treatment.

Comparison of time-dependent changes in the surface hardness of different composite resins

Objective: The aim of this study was to evaluate the change in surface hardness of silorane-based composite resin (Filtek Silorane) in time and compare the results with the surface hardness of two methacrylate-based resins (Filtek Supreme and Majesty Posterior). Materials and Methods: From each composite material, 18 wheel-shaped samples (5-mm diameter and 2-mm depth) were prepared. Top and bottom surface hardness of these samples was measured using a Vickers hardness tester. The samples were then stored at 37°C and 100% humidity. After 24 h and 7, 30 and 90 days, the top and bottom surface hardness of the samples was measured. In each measurement, the rate between the hardness of the top and bottom surfaces were recorded as the hardness rate. Statistical analysis was performed by one-way analysis of variance, multiple comparisons by Tukeys test and binary comparisons by t-test with a significance level of P = 0.05. Results: The highest hardness values were obtained from each two surfaces of Majesty Posterior and the lowest from Filtek Silorane. Both the top and bottom surface hardness of the methacrylate based composite resins was high and there was a statistically significant difference between the top and bottom hardness values of only the silorane-based composite, Filtek Silorane (P < 0.05). The lowest was obtained with Filtek Silorane. The hardness values of all test groups increased after 24 h (P < 0.05). Conclusion: Although silorane-based composite resin Filtek Silorane showed adequate hardness ratio, the use of incremental technic during application is more important than methacrylate based composites.

Evaluation of Different Restoration Combinations Used in the Reattachment of Fractured Teeth: A Finite Element Analysis

Objective The purpose of this study was to test different restoration combinations used for constructing fractured endodontically treated incisors by reattaching their fractured fragments. Methods Seven types of 3-D FEM mathematical root canal-filled models were generated, simulating cases of (OB) reattaching fractured fragments; (CrPL) reattaching fractured fragments + ceramic palatinal laminate; (CmPL) reattaching fractured fragments + composite palatinal laminate; (CM) reattaching fractured fragments + coronal 1/3 of the root was filled using core material; (BP) reattaching fractured fragments + glass fiber post; (CP) composite resin restoration + glass fiber post; and (OC) composite resin restoration. A 100-N static oblique force was applied to the simulated teeth with 135° on the node at 2 mm above the cingulum to analyze the stress distribution at the tooth. Results For enamel tissue, the highest stress values were observed in model BP, and the lowest stress values were observed in model CmPL. For dentine tissue, the highest stress concentrations were observed around the fracture line for all models. Conclusions Reattachment of fractured fragments by bonding may be preferred as a restoration option for endodontically treated incisors; also, palatinal laminate decreases the stress values at tooth tissues, especially at the enamel and the fracture line.

Volumetric Evaluation of Void/Gap Formation and Microleakage Cementing Fiber Posts on Extracted Teeth with Three Different Cements: Void Formation and Microleakage

PURPOSE To evaluate microleakage in roots restored with fiber posts cemented using three different luting cements, to measure the volume of voids/gaps within the obturated/postcemented root canals, and to examine whether microleakage and the volume of voids/gaps were correlated. MATERIALS AND METHODS Thirty-six extracted human mandibular incisors were decoronated, and the root canals were obturated using gutta-percha and sealer in the experimental groups (n = 30). Six roots were used as controls. A standard post space was prepared, and an identically sized fiber post was cemented in each experimental specimen using one of three luting cements (Panavia F2.0, Bifix SE, GC FujiCEM; n = 10 each). The specimens were scanned using micro-computed tomography, and the volume of voids/gaps was determined. The specimens were then subjected to a fluid filtration assay to evaluate microleakage. RESULTS The volume of voids/gaps was significantly lower in the GC FujiCEM group, and significantly less microleakage occurred in the Bifix SE group compared with other groups (both p < 0.001). A significant correlation between the volume of voids/gaps and leakage was found only in the Panavia F2.0 group (p = 0.003; r = 0.830). No such correlation was found in the analysis of all groups combined. CONCLUSIONS The group with the greatest volume of voids/gaps (Bifix SE) showed the least microleakage, and the group with the smallest volume of voids/gaps (GC FujiCEM) showed the most microleakage. Panavia F2.0 ranked between and exhibited significant correlation.

Effects of three different bleaching agents on microhardness and roughness of composite sample surfaces finished with different polishing techniques

Background The aim of this study was to evaluate effects of different polishing methods and whitening agents on surface hardness and roughness of nano-hybrid composite resin. Material and Methods In total, one hundred twenty disc-shaped specimens were prepared to nano-hybrid composite (Charisma Diamond). 60 samples were used for microhardness measurements and the others were used for the evaluation of surface roughness. Samples were divided randomly into two subgroups (n = 30 each). In first group a low-viscosity liquid polishing agent (Biscover LV) was applied. In the second group, nothing was applied. All the samples were stored in distilled water at 37°C for 24 h. After initial measurements were completed, samples were divided randomly into three subgroups for bleaching application. 10% carbamide peroxide (Opalescence PF), 45% carbamide peroxide (Opalescence PF Quick), 38% hydrogen peroxide (Opalescence Boost) was applied. Then microhardness and surface roughness measurements of samples were repeated and data were recorded as final values for each sample. Results When the polishing techniques were compared, no signicant difference was observed in surface hardness and roughness. When the bleaching agents were compared, the 10% carbamide peroxide and 38% hydrogen peroxide containing bleaching agent groups showed statistically significant differences between pre- and post-procedure hardness values (p<0.05). Conclusions Office-type bleaching agent containing CP was observed to be more secure for composite resins than other bleaching agents. No negative effect of glaze materials on the protection of surface roughness and hardness of composite resin was observed. Key words:Composite resin, bleaching, surface hardness, surface roughness.

Efficacy of Palatal Applications on Fracture Resistance of Reattached Maxillary Central Incisors: An In Vitro Study

The purpose of this study was to evaluate the effects of different palatal applications on fracture strength of the fractured anterior tooth. Sixty caries-free human maxillary incisors were used. Endodontic treatments of the teeth were performed. Then, the teeth were divided randomly into five groups (n = 12). Crowns of all teeth in groups A–D were cut with diamond discs at a fixed distance of 3 mm from the incisal margin in a plane normal to the buccal surface. In all groups, coronal fragments were reattached to the remaining teeth by bonding with hybrid composite resin. After then, the teeth were restored to the following; group A, bonding and palatal laminate; group B, bonding and creation of a vertical groove; group C, bonding and creation of two slot grooves; group D, bonding only; and group E, intact tooth. It was lesser in group B than in groups C and E (p = 0.007 and p = 0.006, resp.) and lesser in group D than in groups A, C, and E (p = 0.002, p < 0.001, and p < 0.001, resp.). Within the limitations of this in vitro study, it can be concluded that methods employing palatinal laminate and small grooves are clinically feasible for the reattachment of tooth fragments to incisors.

An in vitro evaluation of the effects of desensitizing agents on microleakage of Class V cavities

Background The aim of this study was to evaluate the effect of a desensitizing agent on microleakage of Class V cavities. Material and Methods 72 premolar teeth were used. There were 6 groups. Class V restorations were prepared with two different restorative materials (Equia fil, GC, America and Grandio, VOCO, Germany) and two adhesive systems (Clearfil SE Bond, Kuraray, Japan and S3 Bond Plus, Kuraray, Japan) with and without desensitizing agent (Gluma Desensitizer, Heraeus Kulzer, Germany). Restorations were polished with aluminum oxide abrasive discs. Then a range of 5 - 55C thermocycling was performed 10.000 times. The microleakage of restorations was examined with dye penetration method (Basic fuchsine). Bonferroni corrections and Kruskal-Wallis test were used to determine the significance of differences in occlusal and gingival dye penetration scores between groups. Results There was no stastistical significance between the occlusal and gingival microleakage scores within the groups were shown. Conclusions It can be concluded that use of desensitizing agent under both high viscosity glass ionomer restorative materials and resin composites doesn’t affect the microleakage. Key words:High viscosity glass ionomer cement, composite resin, desensitizing agent, microleakage.

Evaluation of different restoration techniques on fracture resistance of teeth with palatinal cusp fracture

Abstract We evaluated reattached tooth fragments in terms of fracture resistance in endodontically treated maxillary premolars with one remaining wall. In total, 60 double-rooted, mature, human maxillary premolars with double canals were used. Ten intact teeth were served as a control group without any application. After endodontic treatment, the palatal wall of the teeth was cut parallel to the horizontal axis on the cementoenamel junction using a diamond disc. The teeth were randomly divided into five groups (n = 10) and were restored as follows. Group 1: restored with composite resin; Group 2: palatal wall bonded to the teeth using adhesive resin, then restored with composite resin; Group 3: teeth restored as in Group 2, plus a post space prepared below 2 mm from the palatinal cusp horizontally, then fibre post bonded using adhesive resin cement; Group 4: cavity enlarged to a depth of 2 mm in the cusp of the palatal wall, then restoration performed as in Group 2; and Group 5: fibre post placed in the root canal and then restoration performed as in Group 1. Failure load testing was performed with a universal testing machine. Kruskal–Wallis and Conover’s multiple comparison tests were used to analyse the data. In the restoration groups the highest median load at failure was observed in Group 4, in which cusp capping was used; the lowest was found in Group 3, in which a horizontal fibre post was applied with the reattached tooth fragments.

Transdental ışık uygulamasının kompozit rezinlerin polimerizasyonu üzerine etkisi

Amac: Bu calismanin amaci, farkli kalinliklarda dentin disklerinin uzerinden transdental isik uygulanmasinin kompozit rezinin polimerizasyonu uzerine etkisini Fourier Transform Infrared Spectroscopy (FTIR) ve Vickers mikrosertlik testleri ile incelemektir. Gerec ve Yontemler: Curuksuz alt 3. buyuk azi dislerin bukkal yuzeylerinden 1, 2 ve 3 mm kalinlikta dentin diskleri hazirlandi. 5 mm capinda ve 2 mm derinliginde teflon kaliplarin ici hibrit tip bir kompozit rezin (Clearfil Majesty Esthetic) ile dolduruldu ve kompozit materyalin icerisine bir ucu dijital termometreye bagli isil cift yerlestirildi. Daha sonra kompozit rezin uzerine Grup 1’de; 1 mm kalinliginda dentin diski, Grup 2’de; 2 mm kalinliginda dentin diski veya Grup 3’de; 3 mm kalinliginda dentin diski yerlestirildi. Takiben kompozit rezin dentin disklerinin uzerinden LED isik cihazi ile 40 sn isik uygulanarak polimerize edildi. Kontrol grubunda ise kompozit rezin ornekler 10 mm kalinliginda bir cam uzerinden polimerize edildi. Her bir grup icin toplam 10 ornek hazirlandi. Polimerizasyon sonrasi dijital termometre ile isi artisi kaydedilen orneklerin besi yuzey sertlik testinde diger besi polimerizasyon miktarinin tespit edilmesi amaciyla kullanildi. Orneklerin polimerizasyon miktari FTIR ile yuzey sertlik olcumleri ise Vickers mikrosertlik olcum cihazi kullanilarak incelendi. Elde edilen bulgularin istatistiksel degerlendirmesi tek yonlu varyans analizi (ANOVA) ve Tukey coklu karsilastirmalari kullanilarak yapildi. Bulgular: Calismada polimerizasyon sirasinda kompozit materyal icerisinde olusan isi artis miktarinin deney gruplari arasinda farklilik gosterdigi gozlendi. En yuksek polimerizasyon miktari 1 mm’lik dentin diskinin kullanildigi Grup 1’de (%95.16), en dusuk polimerizasyon miktari ise 3 mm’lik dentin diskinin kullanildigi Grup 3’de (%77) elde edildi (p

Endodontik tedavi görmüş dişlerin konservatif restorasyonları

Asiri madde kaybi olan endodontik tedavi gormus arka grup dislerin restorasyonunda kullanilacak restoratif materyalin ve restorasyon tekniginin secimi bu dislerin kirilmaya karsi dayanikliliklarini arttirmak icin oldukca onemlidir. Kompozit rezin, bu tip dislerin restorasyonunda amalgamdan daha fazla tercih edilen bir materyaldir. Kompozit rezinin gunumuzde oldukca gelismis olan adeziv sistemlerle birlikte kullaniminin dis dokusunu guclendirici etkisinin bulundugu bilinen bir gercektir. Bunun yani sira endodontik tedavi gormus dislerin kirilmaya karsi dayanimlarini arttirmak amaciyla kok kanalina post yerlestirilmesi, tuberkullerin kaplanmasina olanak saglayan onley restorasyonlarin uygulanmasi, kompozit materyali icerisine fiber ag yerlestirilmesi veya bunlarin birlikte kullanimi gibi degisik restorasyon teknikleri kullanilabilir. Bu derlemede bu tekniklerin endodontik tedavi gormus dislerin kirilmaya karsi etkileri tartisilacaktir.