Publications by authors named "Mert Ocak"

22 Publications

  • Page 1 of 1

Evaluation of the Effects of Locally Applied Rosuvastatin on Bone Formation in a Three-Dimensional Reconstruction Rabbit Xenograft Model.

Turk J Med Sci 2021 Aug 25. Epub 2021 Aug 25.

Background/aim: Guided bone regeneration (GBR) is commonly performed to repair bone defects, and rigid occlusive titanium barriers play a vital role in bone formation in regions with no prior bone tissue. The statin, rosuvastatin (RSV), strongly affects bone apposition when applied locally. Here, we aimed to evaluate the anabolic effects of locally applied RSV with a xenograft placed on rabbit calvaria.

Materials And Methods: Two rigid occlusive titanium caps were used in 16 rabbits after decorticating the calvarial bone. In the control group, the area under the cap was filled with a xenograft, while in the RSV group, a xenograft in combination with RSV (1 mg) was used. In both groups, at 6 and 12 weeks, new bone, residual graft, soft tissue areas, and histological and radiological bone volume were evaluated.

Results: At 12 weeks, histologically, the RSV group exhibited superior new bone proportion values, and radiologically, new bone and total bone volume in the RSV group were significantly higher than in the control group (p<0.05); there were no significant differences at 6 weeks (p>0.05).

Conclusion: Per our results, RSV applied locally under a titanium barrier on an area to be repaired with bone grafts increases new bone and total bone volume.
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http://dx.doi.org/10.3906/sag-2011-109DOI Listing
August 2021

The retreatment abilities of ProTaper Next and F6 Skytaper: a micro-computed tomography study.

Eur Oral Res 2021 May;55(2):74-79

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara,Turkey.

Purpose: The aim of this study was to evaluate the retreatment abilities of the ProTaper Next (PTN) and F6 SkyTaper (F6) systems by using micro-computed tomography (microct), radiographic and microscopic imaging techniques.

Materials And Methods: The root canals of twenty-six extracted mandibular premolar teeth were prepared and obturated. For the retreatment procedure, the teeth were randomly divided into two equal groups according to endodontic instruments: PTN (X4) and F6 (#40/.06). Pre- and post-operative filling material volumes were measured with micro-ct, and areas were measured with radiographic and microscopic imaging techniques. The percentages of residual material were calculated, and then statistically compared. The significance level was set at p<0.05.

Results: There was no statistically significant difference between F6 and PTN for retreatment efficacy in the micro-ct and radiographic imaging techniques (p>0.05). PTN demonstrated better cleaning ability when evaluated by microscopic imaging. (p<0.05). The correlation was moderate between micro-ct and radiographic, and micro-ct and microscopic imaging groups; however, it was strong between radiographic and microscopic imaging methods.

Conclusion: The PTN and F6 files had similar effects in the removal of filling material with microct evaluation. The radiographic imaging method gave similar results with micro-ct imaging.
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http://dx.doi.org/10.26650/eor.20210009DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8244941PMC
May 2021

Investigation of the effect of ghrelin on bone fracture healing in rats.

Clin Exp Pharmacol Physiol 2021 Oct 5;48(10):1382-1390. Epub 2021 Jul 5.

Department of Biochemistry, Bakırköy Training and Research Hospital, Health Sciences University, İstanbul, Turkey.

Ghrelin is known to have effects on proliferation and differentiation of osteoblasts and improvement of bone mineral density in rats. However, no experimental research on ghrelin's effects on fracture healing has been reported. In this context, the effect of ghrelin on the union of femoral shaft fractures was examined in this study by evaluating whether ghrelin will directly contribute to fracture healing. Forty male Wistar-Albino rats were divided into two groups as control and experimental (ghrelin treated) and standard closed shaft fractures were created in the left femurs of all rats. Daily ghrelin injections were applied to the experimental groups and equal numbers of rats were killed after 14 and 28 days following fracture formation. Tissue samples were examined with radiological, biomechanical, biochemical and histological analyses. Densitometry study showed that bone mineral density was improved after 28 days of ghrelin treatment compared to control. On histological examination, at the end of the 14 and 28 days of recovery, significant union was observed in the ghrelin-treated group. The ghrelin-treated group had higher breaking strength and stiffness at the end of 28 days of recovery. Biochemically, ALP levels were found to be higher in the ghrelin-treated group at the end of 28 days of recovery. Results showed that ghrelin directly contributes to fracture healing and it is promising to consider the effect of ghrelin on fracture healing in human studies with pharmacological applications.
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http://dx.doi.org/10.1111/1440-1681.13544DOI Listing
October 2021

Evaluation of the detectability of early mandible fracture healing findings in terms of vitality aspect by using micro-CT technology in postmortem interval.

Leg Med (Tokyo) 2021 Sep 1;52:101914. Epub 2021 Jun 1.

Ankara University, Faculty of Dentistry, Department of DentoMaxillofacial Radiology, Ankara, Turkey.

The purpose of the present study was to investigate the vitality aspect of mandibular fractures using micro-CT in the analysis of bone mineral density and other bone microstructure trabecular parameters in the postmortem interval. This study included 72 female Wistar rats. In the study groups, the rats' mandibles were first fractured and after three days of living, the rats were sacrificed. In the control groups, the rats were sacrificed first and then the mandibles were fractured. All rats were left for a natural putrefaction period according to their group's time as week-0, week-1, week-2, week-4, week-8, and week-12. All fractured hemi-mandibles were scanned by micro-CT and analyzed in terms of BMD and other bone trabecular microstructures. BMD and the other bone trabecular microstructures, such as bone volume, percent bone volume, trabecular separation, and trabecular pattern factor, showed statistically significant differences in both the study and control groups (p ≤ 0.05). There were statistically significant differences between the study and control groups in comparisons of BMD in groups 1, 2, 3, 4 and 5, bone volume and percent bone volume in groups 1 and 3, bone surface and bone surface density in group 6, trabecular separation in group 1, and trabecular number, trabecular pattern factor, and structural model index in group 6. Micro-CT scanning and analysis of BMD and other bone trabecular microstructure parameters for evaluation of vitality aspects of mandible fractures in the PMI has various valuable results that should provide guidance for possible studies in the future.
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http://dx.doi.org/10.1016/j.legalmed.2021.101914DOI Listing
September 2021

Effects of various thicknesses and levels of mineral trioxide aggregate coronal plugs on nanoleakage and fracture resistance in revascularization: An in vitro study.

Aust Endod J 2021 Jun 1. Epub 2021 Jun 1.

Department of Anatomy, Faculty of Medicine, Ankara Medipol University, Ankara, Turkey.

The aim of this study was to evaluate the effects of mineral trioxide aggregate (MTA) applied at varying levels and thickness in the cervical region of the root on the leakage and fracture resistance of the simulated immature teeth. 3 study groups (n = 16) (Group 1: 2 mm MTA, Group 2: 4 mm MTA, Group 3: 2 mm MTA+2 mm RMGIC below cementoenamel junction) and 2 control groups (Group 4: Complete canal obturation, Group 5: No coronal plug) were used for the study. Nanoleakage was measured using a micro-computed tomography system. For the fracture resistance test, a universal testing machine was used. The amount of silver nitrate penetration decreased while MTA thicknesses increased (P < 0.001). However, the placement of MTA as a thicker layer did not make any additional contribution on the fracture resistance (P > 0.05). The 4-mm coronal MTA plug can be suggested in RETs for its superior sealing and reinforcement abilities.
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http://dx.doi.org/10.1111/aej.12531DOI Listing
June 2021

Micro-CT Evaluation of the Marginal and Internal Fit of Crown and Inlay Restorations Fabricated Via Different Digital Scanners belonging to the Same CAD-CAM System.

Int J Prosthodont 2021 May/June;34(3):381–389. Epub 2021 Mar 18.

Purpose: To evaluate the marginal and internal adaptation of all-ceramic crowns and inlays fabricated by different scanners of the same CAD/CAM system.

Materials And Methods: All-ceramic crown preparations were performed on typodont maxillary first premolars, and mandibular first molars were prepared for ceramic Class II mesio-occlusal inlays. Two intraoral scanners (CEREC Bluecam and Omnicam, Dentsply Sirona) and one model scanner (CEREC inEos X5, Dentsply Sirona) were used to scan the preparations. All restorations were fabricated by milling single-feldspathic ceramic blocks (CEREC Blocks). The marginal and internal discrepancies of restorations were evaluated via micro-CT analyses.

Results: For linear crown measurements, the marginal gaps were 63.75 μm, 88.24 μm, and 90.89 μm for Bluecam, Omnicam, and inEos X5, respectively. For crowns at central groove areas, the maximum values for Bluecam, Omnicam, and inEos X5 were found to be 144.78 μm, 165.19 μm, and 129.49 μm, respectively. For inlays, the highest range at the midpoint of the axiopulpal line angle for Bluecam, Omnicam, and inEos X5 were determined as 138.57 μm, 184.33 μm, and 179.71 μm, respectively. In volumetric measurements, inEos X5 showed lower gap for both crowns (11.47 mm) and inlays (5.65 mm) compared to both intraoral scanners. These results are within a clinically acceptable range.

Conclusion: When all-ceramic crowns were evaluated, there were generally no significant differences found between scanners for the regional linear measurements, but more gaps occurred in restorations obtained with intraoral scanners for volumetric measurements. On the other hand, when the inlay restorations were evaluated, significant differences were found between groups except for the midpoint of the axio-pulpal line angle and the midpoint of the mesio-gingival margin. However, marginal and internal gaps of both crowns and inlays presented mean values less than 150 μm in many surfaces, which could be considered clinically acceptable.
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http://dx.doi.org/10.11607/ijp.6822DOI Listing
June 2021

Can the Combination of Simvastatin and Melatonin Create a Synergistic Effect on Bone Regeneration?

J Oral Maxillofac Surg 2021 08 5;79(8):1672-1682. Epub 2021 Jan 5.

Professor, Department of Histology and Embryology, Hacettepe University, Faculty of Medicine, Ankara, Turkey.

Purpose: The present study evaluated the potential bone regeneration capacity of combining melatonin and simvastatin, with a goal of producing more osteogenic bone substitutes.

Materials And Methods: A total of 48 male Wistar rats were randomly divided into 4 groups. The following were administered into critical-sized calvarial defects of the rats: Group I-human allograft; Group II-human allograft + 10 mg melatonin; Group III-human allograft + 0.1 mg simvastatin; and Group IV-human allograft + 10 mg melatonin + 0.1 mg simvastatin. Histopathologic, histomorphometric, and microcomputed tomographic evaluations were performed postprocedurally at 4 and 8 weeks. A P value < .05 was considered significant for all evaluations.

Results: Groups II and III had significantly superior regeneration compared to Group I at weeks 4 and 8. Group III had significantly superior regeneration compared to Group II, particularly in week 4. Group IV had significantly superior regeneration compared to all groups at week 8.

Conclusions: The local administration of melatonin and simvastatin resulted in increased new bone mass and quality of bone microstructure than was seen in the control group. Simvastatin shortened the defect regeneration time more effectively than melatonin did. The combined use of melatonin and simvastatin provided a synergic effect on bone regeneration, particularly in the late phase of healing.
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http://dx.doi.org/10.1016/j.joms.2020.12.044DOI Listing
August 2021

Evaluation of Denture Base Adaptation Fabricated Using Conventional, Subtractive, and Additive Technologies: A Volumetric Micro-Computed Tomography Analysis.

J Prosthodont 2021 Mar 24;30(3):257-263. Epub 2021 Feb 24.

Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Ankara University, Ankara, Turkey.

Purpose: An in vitro study to compare the adaptation of denture bases fabricated with 4 different techniques using volumetric 3-dimentional (3D) analysis.

Material And Methods: Edentulous maxillary and mandibular casts were scanned, and standardized denture bases were designed using CAD design software. The same standard tessellation language (STL) data were used to produce the denture bases with 4 different fabrication methods: compression molding (CM), injection molding (IM), PMMA milling (PM), and 3D printing (3D) (n = 11/group). Milled wax denture bases were used to fabricate CM and IM groups. Denture bases placed on edentulous casts were scanned using micro-computed tomography (micro-CT). Volumetric gap between denture base and cast was calculated from 6 locations for maxilla (anterior ridge crest, posterior ridge crest, labial vestibule, buccal vestibule, palate, and posterior palatal seal) and 3 locations for mandible (intermolar, molar, and retromolar) in addition to overall gap measurements for edentulous arches. The data were analyzed with factorial analysis of variance (ANOVA), 1-way ANOVA, and post-hoc Duncan tests. Reproducibility of fabrication methods with regard to each location was assessed using Z test (α = 0.05).

Results: In the maxilla, the highest and lowest palatal gap measurements were recorded for CM (898.44 ± 87.73 mm ) and PM (357.16 ± 57.68 mm ) (p = 0.05). The highest gap measurements for CM and 3D were at palate and, for IM and PM were at posterior ridge crest. In mandible, the volumetric gap measurements for CM were the highest and for PM were the lowest irrespective of location (p = 0.05). PM group showed the best reproducibility and adaptation with the lowest overall mean gaps for both edentulous arches (p = 0.05).

Conclusions: Denture bases milled from PMMA blocks showed better adaptation than 3D printed, or wax milled and conventionally fabricated denture bases for both maxillary and mandibular arches. PMMA milling is a reproducible technique that enables the construction of accurate dentures. Clinicians should be cautious about the palatal gap when the compression molding technique is used. Micro-CT is a valid technique for evaluating the denture base adaptation.
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http://dx.doi.org/10.1111/jopr.13326DOI Listing
March 2021

Marginal and internal fit of feldspathic ceramic CAD/CAM crowns fabricated via different extraoral digitization methods: a micro-computed tomography analysis.

Odontology 2021 Apr 26;109(2):440-447. Epub 2020 Oct 26.

Private Practice, Istanbul, Turkey.

The aim of this study was to compare the fit of feldspathic ceramic crowns fabricated via 3 different extraoral digitizing methods. Twelve maxillary first premolars were prepared and 36 single crowns were fabricated via 3 extraoral digitizing methods using a laboratory scanner (n = 12): (1) scanning the typodont (ST [control] group); (2) scanning the impression (SI group); (3) scanning the stone cast (SC group). Micro-computed tomography was used to calculate two-dimensional marginal-internal gap and the three-dimensional volumetric gap between the crowns and their corresponding dies. The measured gaps were divided into 6 location categories as follows: marginal gap (MG), finish line gap (FLG), axial wall gap (AWG), cuspal gap (CG), proximal transition gap (PTG), and central fossa gap (CFG). The correlation between each of the 3 extraoral digitizing methods and the adaptation status of the crown margins were also evaluated. The Wilcoxon signed-rank test, Spearman's rank test, and Chi-square test were used for data analysis (α = 0.05). The marginal gaps in the ST, SI, and SC groups differed significantly (24, 198 and 117.6 µm, respectively) (p < 0.05). Significant differences were found between the groups with regard to internal gap measurements, with SI representing higher gap measurements at FLG, PTG and CFG locations (p < 0.05). 3D volumetric gap measurements did not differ significantly (p > 0.05). Under-extended margins observed in the SI and SC groups were correlated with the digitizing method (Cramer's V-square: 0.14). When performing extraoral digitalization, clinicians should choose to scan the stone cast as scanning the stone cast resulted in better internal and marginal fit compared to scanning the impression.
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http://dx.doi.org/10.1007/s10266-020-00560-6DOI Listing
April 2021

Micro-ct findings of concentrated growth factors (cgf) on bone healing in masquelet's technique-an experimental study in rabbits.

Arch Orthop Trauma Surg 2020 Sep 18. Epub 2020 Sep 18.

Department of Orthopaedics, University of Health Sciences Ankara Training and Research Hospital, Ankara, 06340, Turkey.

Introduction: A recent histopathological and immunohistochemical study has proved that the addition of concentrated growth factors (CGF) to the Masquelet's technique contributes to the quality of the membrane formed, in respect of inducing inflammation and proliferation, maintaining vascularization on large diaphyseal bone defects, and increasing the number of stem cells. The aim of the study is comparison of radiological results of this combination treatment by micro-CT.

Materials And Methods: The study was planned on a critical bone defect model in rabbit radius. Group I and Group III were the control groups to which only the Masquelet's technique is applied. Group II and Group IV were CGF groups in addition to the Masquelet's technique. CGF was prepared by centrifugation of rabbit's own blood. For early phase, Groups I and II were evaluated in the 8th week, while for late phase, Group III and Group IV were evaluated in the 12th week. Groups were compared in terms of bony union radiologically by micro-CT(μCT) (New Bone Volume (NBV), Total Bone Volume (TBV) and NBV/TBV) and histopathologically.

Results: The structural parameters, including NBV, TBV, NBV/TBV were higher in the early- (8th week) and late-phase (12th week) CGF group. There was no statistically significant difference between CGF and control groups in early phase, (p = 0.153), while in late phase, CGF group was significantly higher of new bone volume than the control group, 246.3 mm (196.1-258) and 169.6 mm (154.3-235.9), respectively (p = 0.028). For early phase, control group was significantly lower than late-phase control group, 121.8 mm (88.8-144.4) and 169.6 mm3 (154.3-235.9), respectively (p = 0.006). The ratio of New Bone Volume to Total Bone Volume (NBV/TBV ratio) in CGF groups was significantly higher compared to the control groups 27.3% (24.7-29.6), 35.3% (32.1-38.6) (p = 0.032) and 39.7% (36.7-41.6), 55.3% (52-57.5) (p = 0.002), respectively. Histopathologically, Microscopic New Bone Formation had no statistically significant difference between control and CGF groups in early phase (8th week) (p = 0.153), while in late phase (12th week), CGF group had significantly higher amount of new bone formation than the control group, 0.29 µm (0.27-0.36), 0.51 µm (0.42-0.59), respectively (p = 0.008).

Conclusion: The addition of CGF to the Masquelet's technique is an important method for supporting new bone formation in large diaphyseal bone defects.

Level Evidence: Level III, therapeutic/care management.
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http://dx.doi.org/10.1007/s00402-020-03596-zDOI Listing
September 2020

Intramedullary implants coated with cubic boron nitride enhance bone fracture healing in a rat model.

J Trace Elem Med Biol 2020 Dec 23;62:126599. Epub 2020 Jun 23.

Atılım University, Department of Manufacturing Engineering, Ankara, Turkey. Electronic address:

Background: Boron nitride is a biocompatible and an osteo-inductive material for orthopedic applications. The aim of this study was to evaluate the effects of two different allotrope boron nitride coated implants, cubic boron nitride and hexagonal boron nitride, on fracture healing.

Methods: In this experimental study, a total of 24 rats were divided into three groups. Group A was the control group with Kirschner wire without coating, while the wires were coated dominantly by cubic boron nitride in Group B and hexagonal boron nitride in Group C. Then a mid-third femoral fracture was created. The fracture healing was examined in terms of new bone formation with micro-CT analysis and histopathological examination, quantitative measurement of bone turnover metabolites and scintigraphic examination of osteoblastic activity on 28th day post fracture.

Results: Micro-CT measurement results revealed a statistically significant increase in bone volume/tissue volume ratio and bone surface values in group B compared to group A. Cortex diameter and osteoblast counts were statistically higher in group B compared to group A. Inflammatory response was increased in group C compared to groups A and B. Biochemical test results showed significantly increased alkaline phosphatase levels and decreased osteocalcin levels in group B compared to group A. The increase in serum phosphorus and decrease in serum calcium levels was statistically significant in group C compared to Group A.

Conclusion: Both types of boron nitride coating had superior fracture healing features compared to control group. Therefore, c-BN coating can accelerate the fracture healing and could lead to shorten of union time.
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http://dx.doi.org/10.1016/j.jtemb.2020.126599DOI Listing
December 2020

Evaluation of the Amount of Root Canal Dentin Removed and Apical Transportation Occurrence after Instrumentation with ProTaper Next, OneShape, and EdgeFile Rotary Systems.

J Endod 2020 May 6;46(5):662-667. Epub 2020 Mar 6.

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Introduction: The aim of this study was to evaluate the amount of root canal dentin removed and apical transportation occurrence after instrumentation of mesiobuccal canals of maxillary molars with ProTaper Next (PTN [Dentsply Maillefer, Ballaigues, Switzerland]), OneShape (OS [MicroMega, Besançon, France]), and EdgeFile (EF [Edge Endo, Albuquerque, NM]) rotary systems.

Methods: Twenty-seven mesiobuccal canals of maxillary molars were used. Canals were randomly divided into 3 groups for canal preparation: PTN, EF X3, or OS (n = 9 for each group). Micro-computed tomographic imaging was used to measure apical transportation (mm) and the volume of dentin removed (mm). The amount of dentin removed was measured for the coronal portion and for the whole canal length. Superposition of pre- and postoperative cross-sectional apical slices were used to measure apical transportation at 1 mm from the apex; the differences were evaluated using the Kruskal-Wallis test and Wilcoxon analysis. The Spearman correlation coefficient was used to display the relationship between variables for each group. The significance level was set at P < .05.

Results: The percentages of the amount of dentin removed on the coronal portion and the amount removed for the whole canal length were statistically similar between groups (P > .05). The average amount of apical transportation for the PTN, OS, and EF X3 were 0.197, 0.263, and 0.218 mm, respectively. Statistically, there were no significant differences between the 3 rotary instruments for apical transportation.

Conclusions: The amount of dentin removed for the coronal third portion and the whole canal length was similar for the PTN, OS, and EF X3 rotary instruments. Although there were differences in the sizes of apical enlargement, no apical transportation was observed in any of the instrumentation systems.
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http://dx.doi.org/10.1016/j.joen.2020.01.022DOI Listing
May 2020

Locally administrated single-dose teriparatide affects critical-size rabbit calvarial defects: A histological, histomorphometric and micro-CT study.

Acta Orthop Traumatol Turc 2019 Nov 14;53(6):478-484. Epub 2019 Sep 14.

Vocational School of Health, Ankara University, Ankara, Turkey.

Objective: The aim of this study was to evaluate the effect of teriparatide (PTH 1-34, rhPTH) on a rabbit defect model with local xenogen grafts histomorphometrically and radiologically.

Methods: For this purpose, two 10 mm diameter critical-size defects were created in the calvaria of 16 rabbits. In the control group, the defect area was filled with a xenogen graft, while in the teriparatide group (PTH 1-34), a xenogen graft combination with 20 mcg teriparatide was used. For both 4 - week and 8 - week study groups, new bone, residual graft, and soft tissue areas were evaluated as well as bone volume histomorphometrically and radiologically.

Results: Histomorphometrically, there was a significant difference in new bone area values at the 8th week (p < 0.05), but there was no significant difference between the 4 - week values (p > 0.05). There was no statistically significant difference between the groups at both 4 and 8 weeks (p > 0.05). In the radiologically measured total bone volume values, PTH1-34 group values were found to be significantly higher for both 4 - and 8 - weeks values compared to the control groups (p < 0.05).

Conclusion: In this study, rhPTH, which is used locally in defect areas to be repaired with bone grafts, increases both new bone volume and total bone volume.
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http://dx.doi.org/10.1016/j.aott.2019.08.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6938999PMC
November 2019

The micro-CT evaluation of enamel-cement thickness, abrasion, and mineral density in teeth in the postmortem interval (PMI): new parameters for the determination of PMI.

Int J Legal Med 2020 Mar 3;134(2):645-653. Epub 2019 Jul 3.

Faculty of Dentistry, Department of DentoMaxillofacial Radiology, Ankara University, Ankara, Turkey.

Objective: The estimation of time of death or the determination of the postmortem interval (PMI) is one of the most important issues in forensic medicine and odontology. However, evaluation of bone and dental hard tissues in PMI could be challenging due to the lack of objective methods with high accuracy. In this respect, micro-CT analysis which has not been used for postmortem evaluation would be beneficial in evaluating hard tissues such as bones and teeth. Therefore, the aim of the present study was to determine the alterations in the hard dental tissue, mineral density of enamel, and the surface abrasion of hard dental tissues of rats in the PMI period with a relatively novel method, micro-CT.

Methods: The present study included 60 female Wistar rats which were divided into six study groups. The rats were sacrificed at the baseline and were left into nature putrefaction process. The study groups were created based on the PMI period as week-0, week-1, week-2, week-4, week-8, and week-12, which included 10 rats in each group. All hemi-mandibles were collected in the determined timelines and the micro-CT analysis was carried out on each group. Mineral density of enamel and the surface abrasion of hard dental tissues were determined.

Results: The enamel and cement thickness remained the same in the examined PMI periods. Mineral density of the enamel tissues were also similar until the 8th week but the decrease was significant at 12th week (2.313 gHAp cm). Surface abrasion of the dental tissues on weeks 4, 8, and 12 were 0.006, 0.024, and 0.024 mm, respectively.

Conclusion: The present study indicated that surface abrasion and enamel mineral density evaluation via micro-CT can be considered as objective and precise parameters in PMI evaluation in forensic medicine and odontology.
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http://dx.doi.org/10.1007/s00414-019-02104-2DOI Listing
March 2020

Microcomputed Assessment of Transportation, Centering Ratio, Canal Area, and Volume Increase after Single-file Rotary and Reciprocating Glide Path Instrumentation in Curved Root Canals: A Laboratory Study.

J Endod 2019 Jun 30;45(6):791-796. Epub 2019 Mar 30.

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Introduction: The aim of this study was to compare the transportation and centering abilities of the ProGlider (PG; Dentsply-Sirona, Ballaigues, Switzerland), WaveOne Gold Glider (WOGG; Dentsply-Sirona), and R-Pilot (RP; VDW, Munich, Germany) file systems and the changes in the structure model index (SMI), surface area, and root canal volume (after creating the glide path in the mandibular first molar teeth's mesial canals with moderate curvature) using the micro-computed tomographic (micro-CT) method.

Methods: In the present study, 24 mandibular first molar teeth with 2 separate mesial canals and moderate (10°-20°) curvature were used. After scanning with micro-CT imaging before the procedure, the teeth were divided into 3 groups, PG, WOGG, and RP (n = 10/each group), followed by the glide path procedure. After the root canal preparation, changes in the root canals regarding the volume, surface area, SMI, transportation made by the files, and the change of their centering ability in the apical, middle, and coronal third were analyzed by micro-CT imaging. The data were statistically evaluated using 1-way analysis of variance and the Kruskal-Wallis test with a significance level set at 5% (P < .05).

Results: The WOGG and RP file systems showed better centering abilities at all thirds compared with the PG file system (P < .05). No significant difference was found in the apical third between the groups in terms of canal transportation degree (P > .05). However, in the WOGG and RP groups, less transportation was observed in the middle and coronal thirds compared with the PG group (P < .05). When the SMI changed, after the root canal preparation was compared, no significant differences were found between the groups (P > .05). Nevertheless, the changes in volume and surface area of the root canal in the WOGG and RP groups were significantly lower than in the PG group (P < .05).

Conclusions: The WOGG and RP file systems caused similar levels of change in the root canal systems based on all parameters. Moreover, it was determined that the PG file system caused a significantly higher volume and surface area increase than the WOGG and RP file systems.
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http://dx.doi.org/10.1016/j.joen.2019.02.012DOI Listing
June 2019

Evaluation of XP-endo Shaper, Reciproc Blue, and ProTaper Universal NiTi Systems on Dentinal Microcrack Formation Using Micro-Computed Tomography.

J Endod 2019 Mar;45(3):338-342

Anatomy Department, Faculty of Dentistry, Ankara University, Ankara, Turkey.

Introduction: The purpose of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with XP-endo Shaper (XP), Reciproc Blue (RB), and ProTaper Universal (PTU) instruments using micro-computed tomographic (μCT) analysis.

Methods: Thirty extracted mandibular first and second molars with mesial roots having 2 separate canals with an angle between 10°and 20° were randomly assigned to 3 experimental groups (n = 10) according to the different nickel-titanium systems used for root canal preparation: XP, RB, and PTU. The specimens were scanned using μCT imaging before and after root canal preparation. Then, preoperative and postoperative cross-sectional images of the teeth were evaluated to identify the presence of dentinal defects. For each group, the number of microcracks was determined as a percentage rate. The McNemar test was used to determine significant differences before and after instrumentation. The level of significance was set at P ≤ .05.

Results: No new dentinal microcracks were observed in the XP and RB groups. The PTU system significantly increased the percentage rate of microcracks compared with preoperative specimens (P < .05).

Conclusions: Root canal preparations with XP and RB systems might not induce the formation of new dentinal microcracks on the mesial roots of mandibular molars. Further assessments are suggested for the examination of the morphology of microcracks after the use of these instruments.
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http://dx.doi.org/10.1016/j.joen.2018.12.005DOI Listing
March 2019

Investigation of the effects of semaphorin 3A on new bone formation in a rat calvarial defect model.

J Craniomaxillofac Surg 2019 Mar 20;47(3):473-483. Epub 2018 Dec 20.

Department of Periodontology (Head: Prof. Dr. Serdar Çintan), Faculty of Dentistry, Istanbul University, Istanbul, Turkey.

Purpose: This study investigates the effects of semaphorin 3A on new bone formation in an experimental rat model.

Materials And Methods: Cortical bone defects, 5 mm, were created in the calvaria of 40 Wistar rats, which were then separated into three groups: empty defect (control) group, collagen group, collagen + semaphorin 3A group. The bone blocks were harvested after 4 and 8 weeks. New bone formation was assessed by micro-computed tomography (micro-CT), histology, histomorphometry, transmission electron microscope (TEM) and immunohistochemistry.

Results: Increased bone formation was observed in collagen + semaphorin 3A groups both histologically and with micro-CT. In the histomorphometic analysis, the control group had significantly less bone formation compared to both the collagen and collagen + semaphorin 3A group at 4 weeks (p = 0.0001) and 8 weeks (p = 0.0001). The collagen group had significantly less bone formation compared to collagen + semaphorin 3A group both at 4 weeks (p = 0.002) and 8 weeks (p = 0.005). Immunohistochemical analysis revealed that semaphorin 3A inhibited receptor activator of nuclear factor-kB ligand (RANKL) expression and increased the expressions of osteoblastic bone markers at 4 weeks. In TEM analysis, the collagen + semaphorin 3A group had an increased proliferation and bone formation rate at 4 weeks, whereas bone quantity and maturation were enhanced at 8 weeks.

Conclusion: Locally applied semaphorin 3A increases callus formation at 4 weeks and bone formation at 8 weeks. Semaphorin 3A prevents bone resorption by inhibiting osteoclasts and increases bone formation by inducing osteoblasts.
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http://dx.doi.org/10.1016/j.jcms.2018.12.010DOI Listing
March 2019

Evaluation of maxillary trabecular microstructure as an indicator of implant stability by using 2 cone beam computed tomography systems and micro-computed tomography.

Oral Surg Oral Med Oral Pathol Oral Radiol 2019 Mar 1;127(3):247-256. Epub 2018 Dec 1.

Department of Dentomaxillofacial Radiology, Faculty of Dentistry, Gulhane Health Sciences University, Ankara, Turkey.

Objective: The aim of this study was to assess the trabecular microarchitecture of the maxilla by using cone beam computed tomography (CBCT) and micro-computed tomography (micro-CT) ex vivo.

Study Design: Seventeen maxillary cadaver specimens were scanned by using micro-CT and CBCT devices. Samples were scanned with 2 CBCT devices at different voxel sizes (0.08, 0.125, and 0.160 mm for 3-D Accuitomo 170; 0.75 and 0.200 mm for Planmeca Promax 3-D Max). Morphometric parameters, such as bone volume/total volume (BV/TV) ratio, trabecular thickness (Tb.Th), trabecular separation (Tb.Sp), trabecular number (Tb.N), and degree of anisotropy (DA) were assessed by using CTAnalyzer software. Bland-Altman limits of agreement and intraclass correlation coefficient (ICC) were performed to evaluate agreement between CBCT and micro-CT in consideration of measured morphometric parameters. Statistical significance was set at P < .05.

Results: The BV/TV, Tb.Th, Tb.Sp, and DA values were higher for CBCT images compared with micro-CT images, whereas the Tb.N value was lower with CBCT images than with micro-CT images. The BV/TV and DA parameters showed the highest agreement between CBCT and micro-CT devices (ICC = 0.421 for BV/TV and ICC = 0.439 for DA; P < .01).

Conclusions: The BV/TV and DA parameters measured on CBCT obtained at the smallest voxel size were found to be useful for the assessment of maxillary trabecular microstructure.
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http://dx.doi.org/10.1016/j.oooo.2018.11.014DOI Listing
March 2019

Obturation quality of calcium silicate-based cements placed with different techniques in teeth with perforating internal root resorption: a micro-computed tomographic study.

Clin Oral Investig 2019 Feb 5;23(2):805-811. Epub 2018 Jun 5.

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Objectives: To evaluate and compare the obturation quality of mineral trioxide aggregate (MTA) and Biodentine placed with hand condensation or indirect ultrasonic activation technique in teeth models simulating perforating internal root resorption (IRR) using micro-computed tomographic (micro-CT) imaging.

Materials And Methods: Standardized models with perforating IRR cavities were created using 40 extracted single-rooted human teeth and randomly divided into four groups (n = 10). The specimens were obturated with either MTA or Biodentine and the placement technique applied was either hand condensation or indirect ultrasonic activation. Micro-CT scans were performed for the volumetric analysis of voids and filling materials in the resorption cavities and apical portion of the specimens. Data were analyzed using one-way analysis of variance and paired t test.

Results: No significant difference was observed between the groups in terms of the percentage volume of filling materials (p > 0.05). The apical portion of the specimens significantly presented less percentage volume of filling materials than the resorption cavities in each group (p < 0.05).

Conclusions: No placement technique produced void-free fillings in teeth with perforating IRR. There was no significant difference between the obturation quality of Biodentine and MTA. The obturation quality in the apical portion of the root canals was inferior than that in the resorption cavities.

Clinical Relevance: The obturation of the apical region of teeth with perforating IRR is challenging irrespective of the material type and placement technique.
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http://dx.doi.org/10.1007/s00784-018-2502-2DOI Listing
February 2019

Evaluation of 3 Different Retreatment Techniques in Maxillary Molar Teeth by Using Micro-computed Tomography.

J Endod 2018 Mar 8;44(3):480-484. Epub 2017 Dec 8.

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Introduction: Nonsurgical retreatment procedure involves the complete removal of the previous filling material to allow thorough instrumentation, disinfection, and refilling of root canal system. We aimed to determine the residuals of the root-filling material by using 3 different retreatment techniques with the aid of micro-computed tomography.

Methods: Thirty extracted human maxillary molar teeth were included. All root canals were also obturated with F2 ProTaper single cones and AH Plus sealer. The following retreatment techniques were performed: group 1, ProTaper retreatment files; group 2, Mtwo retreatment files; and group 3, ProFile files. For the assessment of residual filling material, preoperative and postoperative micro-computed tomography scans were compared with each other, and the working time was recorded. One-way analysis of variance was used to analyze the differences between the groups. The significance level was set at P < .05.

Results: None of the retreatment techniques were capable of removing the whole filling material. The percentages of the residual filling materials for groups 1, 2, and 3 were 34.45, 45.43, and 23.63, respectively. There was a statistically significant difference between groups 2 and 3 (P < .05). ProTaper and ProFile instruments required less time for the removal of filling materials when compared with Mtwo instrument.

Conclusions: ProFile files revealed the best results for endodontic retreatment in terms of both removing capacity and time requirement.
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http://dx.doi.org/10.1016/j.joen.2017.09.006DOI Listing
March 2018

Micro-computed Tomographic Evaluation of Dentinal Microcrack Formation after Using New Heat-treated Nickel-titanium Systems.

J Endod 2017 Oct 27;43(10):1736-1739. Epub 2017 Jul 27.

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Introduction: The aim of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with HyFlex CM (Coltène/Whaledent, Altstätten, Switzerland), HyFlex EDM (Coltène/Whaledent), Vortex Blue (Dentsply Tulsa Dental Specialties, Tulsa, OK), and TRUShape (Dentsply Tulsa Dental Specialties) systems using micro-computed tomographic (micro-CT) analysis.

Methods: Forty human mandibular incisors with 1 and straight root canals were randomly assigned to 4 experimental groups (n = 10) and 1 control group for root canal preparation: group 1, HyFlex CM; group 2, HyFlex EDM; group 3, Vortex Blue; and group 4, TRUShape. The specimens were scanned using high-resolution micro-CT imaging before and after root canal preparation. Afterward, preoperative and postoperative cross-sectional images of the teeth were screened to identify the presence of dentinal defects. The number of microcracks was determined as a percentage for each group.

Results: Before and after canal preparation, 36,152 cross-sectional images were examined. Four thousand four hundred fifty-two (12.31%) dentinal defects were observed. No new microcracks were observed after root canal instrumentation with the tested systems.

Conclusions: Root canal preparation with the HyFlex CM, HyFlex EDM, Vortex Blue, and TRUShape systems did not induce the formation of new dentinal microcracks on straight root canals of mandibular incisors.
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http://dx.doi.org/10.1016/j.joen.2017.05.024DOI Listing
October 2017

Effect of ProTaper Gold, Self-Adjusting File, and XP-endo Shaper Instruments on Dentinal Microcrack Formation: A Micro-computed Tomographic Study.

J Endod 2017 Jul 2;43(7):1166-1169. Epub 2017 May 2.

Department of Anatomy, Faculty of Medicine, Hacettepe University, Ankara, Turkey.

Introduction: The aim of the present study was to evaluate the frequency of dentinal microcracks observed after root canal preparation with ProTaper Universal (PTU; Dentsply Tulsa Dental Specialties, Tulsa, OK), ProTaper Gold (PTG; Dentsply Tulsa Dental Specialties), Self-Adjusting File (SAF; ReDent Nova, Ra'anana, Israel), and XP-endo Shaper (XP; FKG Dentaire, La Chaux-de-Fonds, Switzerland) instruments using micro-computed tomographic (CT) analysis.

Methods: Forty extracted human mandibular premolars having single-canal and straight root were randomly assigned to 4 experimental groups (n = 10) according to the different nickel-titanium systems used for root canal preparation: PTU, PTG, SAF, and XP. In the SAF and XP groups, the canals were first prepared with a K-file until #25 at the working length, and then the SAF or XP files were used. The specimens were scanned using high-resolution micro-computed tomographic imaging before and after root canal preparation. Afterward, preoperative and postoperative cross-sectional images of the teeth were screened to identify the presence of dentinal defects. For each group, the number of microcracks was determined as a percentage rate. The McNemar test was used to determine significant differences before and after instrumentation. The level of significance was set at P ≤ .05.

Results: The PTU system significantly increased the percentage rate of microcracks compared with preoperative specimens (P < .05). No new dentinal microcracks were observed in the PTG, SAF, or XP groups.

Conclusions: Root canal preparations with the PTG, SAF, and XP systems did not induce the formation of new dentinal microcracks on straight root canals of mandibular premolars.
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http://dx.doi.org/10.1016/j.joen.2017.02.005DOI Listing
July 2017
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