Hakan Hamdi Çelik

Comparative investigation of the effects of different materials used with a titanium barrier on new bone formation

OBJECTIVESnIn this study, we aimed to study the effects on new bone formation of autogenous blood, deproteinized bovine bone graft (DBBG), and biphasic calcium phosphate (BCP) bioceramic graft materials placed under titanium barriers.nnnMATERIAL AND METHODSnTwenty-four adult male New Zealand white rabbits were used in this study. Two titanium barriers were fixed on each rabbits calvarium. The study included four groups, one of which was a control group. The experiment groups, autogenous blood, DBBG (Bio-Oss(®) ; Geistlich Biomaterials, Wolhusen, Switzerland) and BCP (4Bone(TM) ; Biomatlante, Vigneux de Bretagne, France) were placed under titanium barriers; in the control group, no materials were used. Half of the animals were sacrificed after 1xa0month, and the rest were sacrificed after 3xa0months. After this, micro-computerized tomography images were taken, and a histomorphometric evaluation was carried out.nnnRESULTSnThe amounts of new bone formation were found to be higher at the third month than at the first month. The differences between the groups were examined with both a micro-computerized tomography and histomorphometric analysis, and no statistical significance was noted in the first month. In contrast, the increase in the amount of new bone formation at the third month was found to be statistically significant only between the DBBG and control groups (Pxa0<xa00.05).nnnCONCLUSIONnAutogenous blood with titanium barriers in guided bone regeneration seems to be as successful as DBBG and BCP bioceramic graft material.

Occlusal Caries Depth Measurements Obtained by Five Different Imaging Modalities

The study aimed to assess the accuracy and reproducibility of occlusal caries depth measurements obtained from different imaging modalities. The study comprised 21 human mandibular molar teeth with occlusal caries. Teeth were imaged using film, CCD, two different cone-beam computerized tomography (CBCT) units and a microcomputer tomography (micro-CT). Thereafter, each tooth was serially sectioned, and the section with the deepest carious lesion was scanned using a high-resolution scanner. Each image set was separately viewed by three oral radiologists. Images were viewed randomly, and each set was viewed twice. Lesion depth was measured on film images using a digital caliper, on CCD and CBCT images using built-in measurement tools, on micro-CT images using the Mimics software program, and on histological images using AxioVision Rel. 4.7. Intra- and inter-rater reliabilities were assessed according to the Bland/Altman method by calculating Intraclass Correlation Coefficients (ICCs). Mean/median values obtained with intraoral systems were lower than those obtained with 3-D and histological images for all observers and both readings. Intra-observer ICC values for all observers were highest for histology and micro-CT. In addition, intra-observer ICC values were higher for histology and CBCT than for histology and intra-oral methods. Inter-observer ICC values for first and second readings were high for all observers. No differences in repeatability were found between Accuitomo and Iluma CBCT images or between intra-oral film and CCD images. Micro-CT was found to be the best imaging method for the ex vivo measurement of occlusal caries depth. In addition, both CBCT units performed similarly and better than intra-oral modalities.

Prevalence of Biofilms and Their Response to Medical Treatment in Chronic Rhinosinusitis without Polyps

Objective. The aim of this study was to investigate the prevalence of biofilms and the effects of medical treatment modalities in chronic rhinosinusitis (CRS) patients without nasal polyps. Study Design. Randomized controlled trial. Settings. Tertiary referral hospital. Subjects and Methods. The authors randomly divided 32 adult patients with CRS without nasal polyps into 2 groups. In the first group (n = 16), oral clarithromycin was administered 500 mg/bid for 2 weeks and then 250 mg/d for the following 6 weeks. In the second group (n = 16), an 8-week course of 200-mcg/d topical mometasone furoate was added to the clarithromycin regimen, identical to the first group. The pre- and posttreatment nasal tissue samples were evaluated by scanning electron microscopy for biofilm prevalence and graded from 0 to 3 according to density and extension. Results. Biofilms were detected in 24 of 32 patients (75%) before the treatment (grades 1-3). Biofilms were detected in 14 of 32 patients (43.8%) after the treatment (grades 1-2). When each group was evaluated independently, there was a significant improvement after the treatment in both groups I and II. When the biofilm grades of group I were compared to those of group II, there was no significant difference both in the pre- and posttreatment evaluation. Conclusion. The prevalence of biofilms in CRS without polyps was 75% in our study. Regression of biofilms to 43% was observed under medical treatment. Adding nasal steroids to macrolides gave no further benefit.

Biofilms in chronic rhinosinusitis with polyps: is eradication possible?

The objective of the study was to reveal if mometasone furoate nasal spray as monotherapy or combined with long-term oral clarithromycin have influence on biofilms in chronic rhinosinusitis with polyps. The study is a randomized controlled trial in a tertiary referral hospital. Thirty-four patients with chronic rhinosinusitis completed the study. In the first group, 19 patients received mometasone furoate nasal spray 200xa0μg once daily for 8xa0weeks. In the second group, 15 patients received oral clarithromycin 500xa0mg twice daily for 2xa0weeks and continued once daily 250xa0mg tablet for subsequent 6xa0weeks, plus mometasone furoate. Scanning electron microscopy was the primary outcome measure. Secondary outcome measures included computerized tomography and sinonasal outcome test-20 items. Mucosal biofilms were detected in 23 of 34 (68xa0%) patients on pretreatment polyp samples. After the treatment, biofilms disappeared in 1 of 11 patients in the first group, whereas the eradication of biofilms was evident in 6 of 12 (50xa0%) patients in the second group. Tomography scores improved in eight patients of each group (42.1 and 53.4xa0%, respectively). The comparison of improvements did not reveal significant difference between the groups. The overall symptom scores improved compared to the baseline levels. The mean changes of −8.8421 and −11.4000 in the first and second group, respectively, were not statistically different. Adding long-term low-dose oral macrolides to nasal steroids was effective in the eradication of biofilm. However, we were not able to demonstrate that combined therapy was superior in terms of the improvement in tomography and symptom scores.

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

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, Raanana, 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. HighlightsMicro–computed tomography was used in the present study to evaluate the presence of dentin defects before and after root canal preparation with new nickel‐titanium rotary systems, precluding the need for cutting the specimens.Root canal preparation with ProTaper Gold, SAF, and XP‐endo Shaper systems did not induce the formation of new dentinal microcracks.However, new microcracks were observed only after root canal preparation with the ProTaper Universal rotary system.

Comparison of micro-computerized tomography and cone-beam computerized tomography in the detection of accessory canals in primary molars

Purpose This study was performed to compare the accuracy of micro-computed tomography (CT) and cone-beam computed tomography (CBCT) in detecting accessory canals in primary molars. Materials and Methods Forty-one extracted human primary first and second molars were embedded in wax blocks and scanned using micro-CT and CBCT. After the images were taken, the samples were processed using a clearing technique and examined under a stereomicroscope in order to establish the gold standard for this study. The specimens were classified into three groups: maxillary molars, mandibular molars with three canals, and mandibular molars with four canals. Differences between the gold standard and the observations made using the imaging methods were calculated using Spearmans rho correlation coefficient test. Results The presence of accessory canals in micro-CT images of maxillary and mandibular root canals showed a statistically significant correlation with the stereomicroscopic images used as a gold standard. No statistically significant correlation was found between the CBCT findings and the stereomicroscopic images. Conclusion Although micro-CT is not suitable for clinical use, it provides more detailed information about minor anatomical structures. However, CBCT is convenient for clinical use but may not be capable of adequately analyzing the internal anatomy of primary teeth.

Micro‐CT Detection and Characterization of Porosity in Luting Cements

PURPOSEnTo evaluate porosity volume and localization in luting cements under fixed dental prostheses after cementation using micro-computed tomography (CT).nnnMATERIALS AND METHODSnSeventy-seven sound molars were circumferentially prepared to receive all-ceramic crowns, and IPS e.max ceramic copings were fabricated according to the manufacturers instructions. For this study, different dental luting cements were used: eight resin-based cements (Variolink II, RelyX ARC, Clearfil Esthetic, BisCem, RelyX U100, Panavia EX, Super Bond C&B, and Multilink Automix), one resin-modified glass ionomer (Ketac Cem Plus), one glass ionomer (Ketac Cem), and one polycarboxylate (Durelon). Specimens were scanned with a micro-CT (SkyScan) for detection and comparison of the cements porosities. Statistical analyses were performed using Kruskal-Wallis one-way ANOVA and Bonferronis adjusted Mann-Whitney U tests.nnnRESULTSnMultilink Automix (Volume = 0.11 ± 0.08 mm3 ; Surface Area = 1.63 ± 1.31 mm2 ), Ketac Cem Plus (Volume = 0.22 ± 0.21 mm3 ; Surface Area = 4.32 ± 3.71 mm2 ), and Variolink II (Volume = 0.34 ± 0.38 mm3 ; Surface Area = 6.47 ± 5.10 mm2 ) contained less porosity (p < 0.001) than all other cements. All other cements were not significantly different from one another (p > 0.05); however, the volume and surface area of the porosity found in the other tested luting cements were significantly greater than those of the Multilink Automix, Ketac Cem Plus, and Variolink II (p < 0.001), all of which demonstrated no significant differences (p > 0.05).nnnCONCLUSIONnThe liquid and powder forms prepared by manually mixing the cements were found to cause greater porosity.

Estrogen as a novel agent for induction of adipose-derived mesenchymal stem cells for osteogenic differentiation: in vivo bone tissue-engineering study.

Background: This study investigated whether the in vivo osteogenic differentiation potential of adipose-derived mesenchymal stem cells is enhanced by 17&bgr;-estradiol. Methods: Thirty Sprague-Dawley rats were randomized and divided into five experimental groups. For the surgical procedure, biparietal full-thickness bone defects (7 mm in diameter) were created. A chitosan-hydroxyapatite scaffold was used as the vehicle system for 17&bgr;-estradiol–loaded nanoparticles and adipose-derived mesenchymal stem cells. The first group, the blank defect group, was the control group. The defects were filled with either scaffold, estradiol, and scaffold; scaffold and adipose-derived mesenchymal stem cells; or estradiol, scaffold, and adipose-derived mesenchymal stem cells as experimental groups. The rats were killed at the end of weeks 4 and 12, and their calvariae were harvested for histologic and microtomographic evaluation. Results: Micro–computed tomographic evaluation of estradiol, scaffold, and adipose-derived mesenchymal stem cells revealed the highest median value (82.59 ± 17.17), and the difference was significant compared with the blank defect group (p = 0.004). Histologic samples demonstrated a significant difference between experimental groups for bone defect repair at the end of weeks 4 and 12 (p = 0.003 and p < 0.001). The estradiol, scaffold, and adipose-derived mesenchymal stem cell group had the highest median score (3.00 ± 0.0) at week 12, which was significantly higher than scores for the scaffold and adipose-derived mesenchymal stem cell group and the blank defect group. Conclusion: 17&bgr;-Estradiol appears to be a novel and promising agent for future cell-based bone tissue-engineering studies.

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

INTRODUCTIONnThe 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.nnnMETHODSnForty human mandibular incisors with 1 and straight root canals were randomly assigned to 4 experimental groups (nxa0=xa010) 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.nnnRESULTSnBefore 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.nnnCONCLUSIONSnRoot 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.

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

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.