Browsing by Author "Eskitascioglu, G."

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Changes in the Surface of Bone and Acid-Etched and Sandblasted Implants Following Implantation and Removal
(Dental Investigations Society, 2016) Eroglu, C.N.; Ertugrul, A.S.; Eskitascioglu, M.; Eskitascioglu, G.
Objective: The aim of this study was to determine whether there are any changes in the surface of bone or implant structures following the removal of a screwed dental implant. Materials and Methods: For this, six individual samples of acid-etched and sandblasted implants from three different manufacturers' implant systems were used. They were screwed in a D1 bovine bone, and they were removed after primary stabilization. The bone and implant surfaces are evaluated with scanning electron microscope. Results: Through examination of the surfaces of the bone prior to implantation and of the used and unused implant surfaces, it was found that inhomogeneity in the implant surface can cause microcracking in the bone. Conclusions: This is attributed to the stress induced during the implantation of self-tapping implants and suggests that a tap drill may be required in some instances to protect the implant surface. © 2016 European Journal of Dentistry.
Direct Restoration of Endodontically Treated Teeth: a Brief Summary of Materials and Techniques
(Springer Science and Business Media B.V., 2015) Belli, S.; Eraslan, O.; Eskitascioglu, G.
The restoration of endodontically treated teeth remains a challenge. The success of the final restoration depends mostly on the structure of the remaining tooth. Although the materials and procedures available today result in successful restoration of root-filled teeth via direct (in situ) techniques, one should first consider the amount of the coronal tooth structure remaining as well as the functional requirements. Restoration using direct composite resin is a good treatment option, but polymerization shrinkage is one of the major limitations of this material. The application of various base materials under the composite resin is an effective method. Covering the cusps with the restorative material is another option to save the remaining tooth structure; however, some materials may be unsuitable in stress-bearing areas. Materials applied to the orifice of a root canal also have a major effect on tooth biomechanics. This article reviews the direct restoration of endodontically treated teeth and discusses the current materials and techniques used for this purpose. © 2015, Springer International Publishing AG.
The Effect of Cavity Shape and Hybrid Layer on the Stress Distribution of Cervical Composite Restorations
(Dental Investigations Society, 2011) Eliguzeloglu, E.; Eraslan, O.; Omurlu, H.; Eskitascioglu, G.; Belli, S.
Objectives: The aim of this finite elemental stress analysis study was to evaluate the effect of cavity shape and hybrid layer on the stress distribution of the mandibular premolar tooth under occlusal loading. Methods: The mandibular premolar tooth was selected as the model based on the anatomical measurements suggested by Wheeler. Four different mathematical models were evaluated: 1) a saucer-shaped non-carious cervical lesion restored with a composite without a hybrid layer, 2) a saucer-shaped non-carious cervical lesion restored with a composite with a hybrid layer, 3) a wedge-shaped non-carious cervical lesion restored with a composite without a hybrid layer, and 4) a wedge-shaped non-carious cervical lesion restored with a composite with a hybrid layer. A 200 N force was applied from the buccal tubercule and central fossa of the premolar tooth. The findings were drawn by the SAPLOT program. Results: In models 2 and 4, the output showed that a hybrid layer acts as a stress absorber. Additionally, when the cavity shape was changed, the stress distribution was very different. Conclusions: Cavity shape and hybrid layer play an important role in stress distribution in cervical restorations.
The Effect of Different Materials and Techniques on Stress Distribution in Cad/Cam Endocrowns
(Springer, 2020) Eskitascioglu, M.; Kucuk, O.; Eskitascioglu, G.; Eraslan, O.; Belli, S.
Computer-aided design/manufacturing (CAD/CAM) endocrowns are commonly applied to strengthen endodontically treated teeth with too much tissue loss. Monolithic or multilayer structures may be used for this purpose. Restorations made with multilayering technique may mimic natural teeth better. The purpose of this finite elemental analysis (FEA) research was to appraise the impact of different materials and application methods on the stress effect in CAD/CAM applied endocrowns. A 3-dimensional mathematical model simulating an endodontically treated mandibular first molar was modeled. The sample was then modified to imitate the ceramic endocrown applied molar tooth. Three FEA models were then created from this main model to simulate the following endocrown structures: 1: lithium disilicate reinforced glass ceramic, 2: monolithic zirconia, 3: multi-layered glass ceramic and glass-fiber endocrown (the core structure was composed of glass-fiber while the crown is prepared by glass ceramic). The SolidWorks/CosmosWorks programs were used as structural analysis programs. The materials used in the study were accepted as homogeneous and isotropic. A 300 N load was applied to the occlusal surfaces of the restored teeth. The results of the study are presented according to the von Mises criteria. The von Mises stresses recorded at the cavity base were 0.417-0.7, 0.6-0.85, and 0.083-0.25 MPa, respectively. The multilayering technique reduced stresses as compared to the other two different designs and materials and showed similar stress distributions with the natural tooth model. Models simulating teeth with a zirconia endocrown showed the highest stresses. The multilayering technique using fiber-reinforced glass ceramic as a core and glass ceramic as a crown reduced the stresses and showed stress distributions similar to natural teeth. This technique can be used to create biomimetic restorations with a core material, which mimics dentin (glass-fiber reinforced ceramic) and crown material, which mimics enamel (glass ceramic).
Effect of Different Mechanical Cleansing Protocols of Dentin for Recementation Procedures on Micro-Shear Bond Strength of Conventional and Self-Adhesive Resin Cements
(Elsevier Sci Ltd, 2013) Bavbek, A. B.; Goktas, B.; Sahinbas, A.; Ozcopur, B.; Eskitascioglu, G.; Ozcan, M.
Service life of debonded indirect dental restorations could be prolonged by recementation. This process requires removal of cement remnants from dentin. This study evaluated the effect of different mechanical cleansing protocols of dentin for recementation procedures on micro-shear bond strength (mu SBS) of conventional and self-adhesive resin cements. The labial surfaces mandibular incisors (N=200) were ground with a low speed saw to expose the corona] dentin. The teeth were randomly divided into two subgroups (n: 100 per group) and received either (a) conventional (Panavia F 2.0, Kuraray, PAN) or (b) self-adhesive (Clearfil SA, Kuraray, CSA) resin cement. Resin cements were condensed into polyethylene molds incrementally and photo polymerized using an LED polymerization unit. Specimens were stored in distilled water at 37 degrees C for 24 h and subjected to mu SBS (0.5 mm/min). Resin cement remnants on bonded dentin surfaces were removed using by (a) composite finishing bur (cb), (b) tungsten carbide bur (ob), (c) ultrasonic scaler tip (sc) or (d) pumice-water slurry (pw). Non-cleaned teeth acted as the control group (cn) (n: 20 per subgroup). After cleaning, the same cement type was rebonded simulating clinical recementation. Failure types were analyzed using optical microscope and Scanning Electron Microscope (SEM). Data (MPa) were analyzed using Wilcoxon Signed Ranks, Mann-Whitney U and Bonferroni tests (alpha=0.05). Overall, CSA (6.42 +/- 2.96) showed significantly lower results than that of PAN cement (7.88 +/- 3.49) (p < 0.05). All cleansing protocols (4.29 +/- 2.17 to 5.82 +/- 2.5) showed significantly lower results than that of the control group (9.84 +/- 4.88) for PAN cement. For CSA cement, all cleansing protocols presented non-significant results (4.25 +/- 2.74 to 6.44 +/- 2.4 MPa) compared to control group (p > 0.05) expect cb method (3.42 +/- 1.47) (p < 0.05). Remnants of cements were detected on dentin surfaces in all groups at varying degrees. SEM showed that while using pumice-water slurry was the least effective for PAN, tungsten carbide bur was the most effective for both cements. All other methods showed similar cleansing efficacy. None of the cleansing protocols yielded to complete removal of resin cement rest on dentin upon recementation for both cements tested. (C) 2012 Elsevier Ltd. All rights reserved.
The Effect of Different Posts on Fracture Strength of Roots With Vertical Fracture and Re-Attached Fragments
(Wiley-blackwell, 2010) Ozcopur, B.; Akman, S.; Eskitascioglu, G.; Belli, S.
P>The aim of this in vitro study was to test the effect of different post systems on fracture strength of roots with re-attached fragments. Root canals of eighty extracted single-rooted human teeth were instrumented (ProFile) and randomly divided into two groups. The roots in the first group were vertically cracked, and the fragments were re-attached using Super Bond C&B (Sun Medical, Tokya, Japan). The roots in the second group were kept sound. Obturation of the roots was performed with MetaSEAL (Sun Medical) and gutta-percha. Post spaces were prepared, and the roots were restored with one of the followings: UniCore (Ultradent), Everstick (Stick Tech), Ribbond (Ribbond), ParaPost (Coltene/Whaledent) (n = 10). Four mm high build-ups were created (Clearfil DC Bond Core; Kuraray, Tokyo, Japan). Compressive loading of the samples was performed after 24 h (1 mm min-1). Mean load necessary to fracture each sample was recorded (Newton) and statistically analysed (One-way anova, t-tests). ParaPost showed the highest fracture strength among the roots with re-attached fragments (P < 0.05). UniCore and ParaPost systems showed similar fracture strength in the sound roots (P > 0.05). Re-attached fragments significantly reduced the fracture strength of roots in UniCore group (P = 0.000). Ribbond post showed mostly repairable fractures. Metal post (ParaPost) showed the highest fracture strength in the roots with re-attached fragments; however, fracture pattern was 41% non-repairable. Re-attached fragments significantly reduced the fracture strength of the roots in UniCore group. Prefabricated posts showed similar fracture strength in the sound roots. Customized post systems EverStick and Ribbond showed mostly repairable failure after loading in sound roots or roots with re-attached fragments.
Effects of Naocl, Edta and Mtad When Applied To Dentine on Stress Distribution in Post-Restored Roots With Flared Canals
(Wiley, 2014) Belli, S.; Eraslan, O.; Eraslan, O.; Eskitascioglu, M.; Eskitascioglu, G.
AimTo evaluate the effect of NaOCl, EDTA and MTAD on the stress distribution and levels in roots with flared canals and three different aesthetic post systems using finite element stress analysis (FEA). MethodologyThree-dimensional (3D) FEA models simulating a maxillary incisor with excessive structural loss and flared root canals were created. The dentine of the first models of each post group was assumed as homogenous, whereas the others were deemed as having their elastic modulus affected up to 100m deep as a result of irrigation protocol (5.25 NaOCl, 17% EDTA and MTAD for 2h). A sound incisor tooth model was used as the control. Restorations were created according to the post system used (pre-fabricated fibre post (PFP)), polyethylene fibre (Ribbond) post and core build-up (RBP), and one-piece milled zirconia post and core (ZP). Ceramic crowns were added to the models. A 300-N static load was applied at the centre of the palatal surface of the models to calculate the stress distributions. The SolidWorks/Cosmosworks structural analysis programmes were used for FEA analysis. Results were presented by considering von Mises criteria. ResultsThe analysis of the von Mises stresses revealed that RBP created less stress in the remaining root dentine when compared to PFP and ZP. ZP maintained the stresses inside its body and reduced stress on the palatal surface of the root; however, it forwarded more stress towards the apical area. NaOCl-, EDTA- and MTAD-treated dentine increased the stresses within the root structure regardless of the effect of the post system used (11-15.4 MPa for PFP, 9.5-13.02 MPa for RBP and 14.2 MPa for ZP). Amongst the irrigation solutions used, EDTA and MTAD increased the stresses more than NaOCl in all models. All the irrigation solutions showed the same stress levels and distributions in the ZP model. ConclusionNaOCl-, EDTA- and MTAD- treated dentine and a rigid post with high elastic modulus may increase fracture risk in roots with flared canals by increasing the stresses within root dentine. Therefore, solutions that alter the elastic modulus of dentine less (such as NaOCl) or an individually shaped post-core system constructed with a material that has an elastic modulus close to dentine (polyethylene fibre) should be used in weak roots.
Influence of Several Fibre-Reinforced Composite Restoration Techniques on Cusp Movement and Fracture Strength of Molar Teeth
(Wiley, 2011) Akman, S.; Akman, M.; Eskitascioglu, G.; Belli, S.
P>Aim To compare mean cusp movement in molar teeth with endodontic access and mesial-occlusal-distal (MOD) cavities before and after restoration with several fibre-reinforced composite restoration techniques under loading and to evaluate the effect of restoration technique on fracture strength. Methodology Reference points were marked at the mesial cusp ridges of extracted human mandibular molar teeth. Digital images were taken under loading (300 N) using a stereomicroscope (Leica MZ16A; Wetzlar, Germany). Three-dimensional (3D) distances between the reference points were recorded (Leica, Stereo-Explorer, 2.1) as controls. Standard MOD cavities were prepared and restored as follows (n = 10), group 1: composite restoration (Clearfil AP-X; Kuraray, Tokyo, Japan); group 2: cavity lined with polyethylene fibre (Ribbond, Ribbond Inc., Seattle, WA, USA) in combination with flowable resin (Protect-Liner F; Kuraray, Tokyo, Japan) before composite restoration; group 3: polyethylene fibre inserted on occlusal surface of the tooth from buccal to lingual after finishing the composite restoration; group 4: missing walls were restored with composite resin and inner surfaces of the axial walls were then reinforced with polyethylene fibre placed circumferentially before the composite restoration. The restored teeth were re-loaded, digital images were re-taken and the 3D distance between the reference points was recorded in mu m. Comparisons of the restoration techniques, the effectiveness of restoration for each group were analysed statistically (Kruskall-Wallis, paired-samples t-test). The teeth were then loaded until failure (5 mm min-1), the data were recorded (N) and analysed statistically (Kruskall-Wallis test). Results A significant difference occurred amongst the groups in terms of cusp movement (P = 0.018). All the groups revealed a decrease in inter-cuspal width when compared to their initial records. The mean values of these decreases were as follows: group 1 17.6 (P = 0.003), group 2 6.7 (not sig), group 3 6.6 (not sig) and group 4 0.85 (not sig) mu m. No significant difference was found amongst the fracture strength values (P = 0.22). In group 1, 90% of the fractures were non-restorable, whereas in group 3 100% of the fractures were restorable. Conclusions Regardless of restoration technique, fibre reinforcement of composite restorations decreased cusp movement in molar teeth with MOD and endodontic access cavities but did not affect fracture strength.
Monoblocks in Root Canals: a Finite Elemental Stress Analysis Study
(Wiley-blackwell, 2011) Belli, S.; Eraslan, O.; Eskitascioglu, G.; Karbhari, V.
Belli S, Eraslan O, Eskitascioglu G, Karbhari V. Monoblocks in root canals: a finite elemental stress analysis study. International Endodontic Journal, 44, 817-826, 2011. Aim To investigate using finite element stress analysis (FEA) primary, secondary and tertiary monoblocks created either by adhesive resin sealers or by different adhesive posts and to evaluate the effect of interfaces on stress distribution in incisor models. Methodology Seven maxillary incisor FEA models representing different monoblocks using several materials were created as follows: (a) primary monoblock with Mineral Trioxide Aggregate; (b) secondary monoblock with sealer (MetaSEAL) and Resilon; (c) tertiary monoblock with EndoREZ; (d) primary monoblock with polyethylene fibre post-core (Ribbond); (e) secondary monoblock with glass-fibre post and resin cement; (f) tertiary monoblock with bondable glass-fibre post; (g) tertiary monoblock with silane-coated ceramic post. A 300 N load was applied from the palatal surface of the crown with a 135 degrees angle to the tooth long axis. Materials used in the study were assumed to be homogenous and isotropic except the glass-fibre post; the results are expressed in terms of von Mises criteria. Results Maximum stresses were concentrated on force application areas (18-22.1 MPa). The stresses within the models increased with the number of interfaces both for the monoblocks created by the sealers (1.67-8.33 MPa) and for the monoblocks created by post-core systems (1.67-11.7 MPa). Conclusions Stresses within roots increased with an increase in the number of the adhesive interfaces. Creation of a primary monoblock within the root canal either by an endodontic sealer or with an adhesive post-core system can reduce the stresses that occur inside the tooth structure.
Retraction: Stress Distribution in Cad/Cam Endocrowns Produced Via Different Materials and Techniques: a Numerical Simulation (Retraction of Vol 52, Pg 812, 2020)
(Springer, 2023) Eskitascioglu, M.; Kucuk, O.; Eskitascioglu, G.; Eraslan, O.; Belli, S.
Stress Distribution in Cad/Cam Endocrowns Produced Via Different Materials and Techniques: a Numerical Simulation
(Springer, 2022) Eskitascioglu, M.; Kucuk, O.; Eskitascioglu, G.; Eraslan, O.; Belli, S.
Computer-aided design/manufacturing (CAD/CAM) endocrowns are commonly applied for the strengthening of endodontically treated teeth with excessive tissue loss. Monolithic or multilayer structures may be used for this purpose. Restorations made with multilayering techniques may better mimic natural teeth. This study assessed the impact of different materials and application methods on the stress state of CAD/CAM endocrowns. To this end, a 3D FEM model simulating an endodontically treated mandibular first molar was elaborated. The sample was then modified to imitate the ceramic endocrown-applied molar tooth. Three FEM models were then developed from this main model to simulate the following endocrown structures: (1) lithium disilicate reinforced glass ceramic, (2) monolithic zirconia, and (3) multilayered glass ceramic and glass-fiber endocrown (i.e., a glass-fiber core structure and glass ceramic crown). The SolidWorks/Cosmosworks software packages were used for structural analysis. The materials used in the study were treated as homogeneous and isotropic. A 300 N load was applied to the occlusal surfaces of the restored teeth. The von Mises stresses were calculated at the cavity base, ranging from 0.417-0.700 MPa, 0.600-0.850 MPa, and 0.083-0.250 MPa, respectively. The multilayering technique provided the lowest stresses and stress distributions comparable with the natural tooth model. Models of teeth restored with zirconia endocrowns showed the highest stresses and were the least applicable in dental pracice.