Halil İbrahim Kılınç

Computerized analysis of occlusal contacts in bruxism patients treated with occlusal splint therapy

PURPOSE Occlusal splints are commonly used to prevent tooth wear caused by bruxism. However, the effects of splints on occlusion are still unclear. Although it is rarely alluded in literature, splints can provoke severe occlusal alterations and other complications. This study was aimed to identify differences in the responses of individuals with bruxism and healthy individuals to a full-arch maxillary stabilization splint in terms of occlusal changes. MATERIALS AND METHODS Occlusal contacts in 20 (5 male, 15 female) bruxism patients and 20 (5 male, 15 female) controls with normal occlusion were evaluated before and after occlusal splint therapy. T-Scan III, a computerized occlusal analysis system, was used to simultaneously measure occlusion and disclusion times as well as left-right and anterior-posterior contact distributions before splint therapy and 3 months after therapy. Wilcoxon and Mann-Whitney U tests were used for statistical analyses (α=.05). RESULTS No differences were found in the posterior contact of bruxism patients before and after stabilization splint treatment. However, differences in posterior contact were observed between bruxists and normal individuals prior to treatment, and this difference disappeared following treatment. CONCLUSION The results of this study showed the use of a stabilization splint may not have an effect on occlusion. However, the area of posterior occlusal contact among bruxists was found to be greater than that of normal individuals. According to this study, the clinical use of splints may be harmless.

Stress distribution of oval and circular fiber posts in amandibular premolar: a three- dimensional finite element analysis

PURPOSE The aim of the present study was to evaluate the effects of posts with different morphologies on stress distribution in an endodontically treated mandibular premolar by using finite element models (FEMs). MATERIALS AND METHODS A mandibular premolar was modeled using the ANSYS software program. Two models were created to represent circular and oval fiber posts in this tooth model. An oblique force of 300 N was applied at an angle of 45° to the occlusal plane and oriented toward the buccal side. von Mises stress was measured in three regions each for oval and circular fiber posts. RESULTS FEM analysis showed that the von Mises stress of the circular fiber post (426.81 MPa) was greater than that of the oval fiber post (346.34 MPa). The maximum distribution of von Mises stress was in the luting agent in both groups. Additionally, von Mises stresses accumulated in the coronal third of root dentin, close to the post space in both groups. CONCLUSION Oval fiber posts are preferable to circular fiber posts in oval-shaped canals given the stress distribution at the post-dentin interface.

Evaluation of the resin cement thicknesses and push-out bond strengths of circular and oval fiber posts in oval-shapes canals

PURPOSE The aim of this study was to evaluate whether the push-out bond strength varies between oval and circular fiber posts, and to examine the effect on the resin cement thicknesses around the posts. MATERIALS AND METHODS Eighteen mandibular premolar roots were separated into two groups for oval and circular fiber posts systems. Post spaces were prepared and fiber posts were luted to the post spaces. Roots were cut horizontally to produce 1-mm-thick specimens. Resin cement thicknesses were determined with a metallographic optical microscope and push-out tests were done. RESULTS No significant differences were observed in terms of push-out bond strength between the oval and circular fiber posts (P>.05) The resin cement thicknesses of the oval posts were greater than those of the circular posts group in the coronal, middle and apical specimens (P<.05). CONCLUSION In the light of these results, it can be stated that resin cement thickness does not affect the push-out bond strength.

Effect of fluid contamination on reverse torque values in bone-level implants.

Introduction: Screw loosening is one of the most common mechanical complications within the prosthetic components of dental implants. Clinicians must know if reverse torque values (RTVs) are affected by contamination of the implant abutment screw hole with either blood, saliva or chlorhexidine. Methods: Forty implants were divided into 4 groups (n = 10). Implants were embedded in epoxy resin and placed in a digital torque meter. Screw holes of 30 implants were contaminated with either chlorhexidine (CG), fresh human saliva (SG), or blood (BG), and the remaining noncontaminated screws served as a control group (NC). Abutment screws were tightened using a hand-held torque meter (25 N·cm). Thermocycling (1500 cycles) was performed, and abutment detorque values were calculated using the digital torque meter. Results: RTVs were lower than insertion torque values for all groups. According to Tukey HSD Test, blood contamination of abutment screws resulted in significantly lower RTVs (18.950 ± 2.641 N·cm) when compared with controls. Conclusions: Blood contamination of abutment screw holes was shown to significantly decrease RTVs. Blood contamination may result in greater loosening of implant screws in clinical practice.

Effect of different provisional cement remnant cleaning procedures including Er:YAG laser on shear bond strength of ceramics

PURPOSE The purpose of this study was to evaluate the effect of provisional cement removal by different dentin cleaning protocols (dental explorer, pumice, cleaning bur, Er:YAG laser) on the shear bond strength between ceramic and dentin. MATERIALS AND METHODS In total, 36 caries-free unrestored human third molars were selected as tooth specimens. Provisional restorations were fabricated and cemented with eugenol-free provisional cement. Then, disc-shaped ceramic specimens were fabricated and randomly assigned to four groups of dentin cleaning protocols (n = 9). Group 1 (control): Provisional cements were mechanically removed with a dental explorer. Group 2: The dentin surfaces were treated with a cleaning brush with pumice Group 3: The dentin surfaces were treated with a cleaning bur. Group 4: The provisional cements were removed by an Er:YAG laser. Self-adhesive luting cement was used to bond ceramic discs to dentin surfaces. Shear bond strength (SBS) was measured using a universal testing machine at a 0.05 mm/min crosshead speed. The data were analyzed using a Kolmogorov Smirnov, One-way ANOVA and Tukey HSD tests to perform multiple comparisons (α=0.05). RESULTS The dentin cleaning methods did not significantly affect the SBS of ceramic discs to dentin as follows: dental explorer, pumice, cleaning bur, and Er:YAG laser. CONCLUSION The use of different cleaning protocols did not affect the SBS between dentin and ceramic surfaces.

Effect of repeated ceramic firings on the marginal and internal adaptation of metal-ceramic restorations fabricated with different CAD-CAM technologies

Statement of problem The use of computer‐aided design and computer‐aided manufacturing (CAD‐CAM) for metal‐ceramic restorations has increased with advances in the technology. However, little is known about the marginal and internal adaptation of restorations fabricated using laser sintering (LS) and soft milling (SM). Moreover, the effects of repeated ceramic firings on the marginal and internal adaptation of metal‐ceramic restorations fabricated with LS and SM is also unknown. Purpose The purpose of this in vitro study was to investigate the effects of repeated ceramic firings on the marginal and internal adaptation of metal‐ceramic copings fabricated using the lost wax (LW), LS, and SM techniques. Material and methods Ten LW, 10 LS, and 10 SM cobalt‐chromium (Co‐Cr) copings were fabricated for an artificial tooth (Frasaco GmbH). After the application of veneering ceramic (VITA VMK Master; VITA Zahnfabrik), the marginal and internal discrepancies of these copings were measured with a silicone indicator paste and a stereomicroscope at ×100 magnification after the first, second, and third clinical simulated ceramic firing cycles. Repeated measures 2‐way ANOVA and the Fisher LSD post hoc test were used to evaluate differences in marginal and internal discrepancies (&agr;=.05). Results Neither fabrication protocol nor repeated ceramic firings had any statistically significant effect on internal discrepancy values (P>.05). Marginal discrepancy values were also statistically unaffected by repeated ceramic firings (P>.05); however, the fabrication protocol had a significant effect on marginal discrepancy values (P<.001), with LW resulting in higher marginal discrepancy values than LS or SM (P<.05). Marginal discrepancy values did not vary between LS and SM (P>.05). Conclusions All groups demonstrated clinically acceptable marginal adaptation after repeated ceramic firing cycles; however, the LS and SM groups demonstrated better marginal adaptation than that of LW group and may be appropriate clinical alternatives to LW.

Effect of chewing on dental patients with total denture: an experimental study

In this study, we have explored the prospect of assessing and following level of total denture adaptation by use of EMG signals recorded during gum chewing. Total of 14 edentulous patients, 6 women and 8 men, with an average age of 63±9 years, were recruited. Separate EMG recordings were obtained from left and right temporalis and masseter muscles of the patients for a period of 10 seconds, while they were chewing a sugar-free gum on their left and right sides. EMG recordings were repeated at three times: before, right after, and six months after the placement of the denture. We have tried to standardize environmental and individual factors during EMG recordings. The EMG data have been pre-processed and analyzed using Discrete Wavelet Transform (DWT) and obtained features were statistically evaluated using the paired sample t-test. Chewing activity on the right and left side is analyzed by making comparisons of muscle activity between before and right-after cases and before and six-months-after denture fixation cases. A comparison between right and left side mastication is also made at different time points. We have suggested and implemented a new test and comparison procedure in order to assess adaptation to denture fixation using EMG analysis. In this study, the results indicate that DWT based EMG analysis is instrumental in evaluating denture adaptation and as time progresses the adaptation to denture and hence chewing efficiency increases in patients with total denture replacement.

Infrared Thermographic Comparison of Temperature Increases on the Root Surface during Dowel Space Preparations Using Circular versus Oval Fiber Dowel Systems

PURPOSE The purpose was to evaluate temperature increases during dowel space preparations with oval and circular fiber dowel systems. MATERIALS AND METHODS This study included 42 single-rooted human mandibular premolars. Roots were scanned with cone-beam computerized tomography (CBCT) to determine the ovoid root canal morphology. Root canals were treated with Ni-Ti rotary instruments and obturated. A second CBCT was taken to determine the thinnest dentin thickness of each root. Roots were randomly divided into two groups (n = 21) according to the fiber dowel system used: group 1, circular fiber dowel system (D.T. Light-Post); group 2, oval fiber dowel system (Ellipson Post). Dowel spaces were prepared using a circular fiber dowel drill and a diamond-coated ultrasonic tip with an oval section under water cooling until 9 mm dowel spaces were obtained. Temperature changes were recorded from the thinnest root surfaces using a FLIR E60 thermal imaging camera. RESULTS Temperature increases were significantly greater with the circular fiber dowel system than with the oval fiber dowel system (p < 0.05). CONCLUSIONS Although both dowel systems generated high temperature increases on root surfaces, the relatively lower temperature increase associated with the use of oval fiber dowels in ovoid canals makes it preferable to the use of circular fiber dowels.

Effect of digital impressions and production protocols on the adaptation of zirconia copings.

Statement of problem. Proper marginal, axial, and occlusal adaptation of dental restorations is essential for their long‐term success. Production protocols including digital impression systems have been developed, but little information is available on the adaptation of zirconia restorations produced via them. Purpose. The purpose of this in vitro study was to compare the effects of digital impression protocols on the marginal, axial, and occlusal adaptation of zirconia copings. Material and methods. Thirty extracted human maxillary premolar teeth without caries or defects were used. The teeth were prepared for zirconia crowns and randomly divided into 3 groups. Zirconia copings were designed at a thickness of 0.5 mm with 30 &mgr;m of simulated die spacer starting 1 mm from the margin of preparations. They were produced using computer‐aided design‐computer‐aided manufacture (CAD‐CAM) protocol with a conventional impression (group Cn) and 2 different production protocols with digital impressions (group C) and group Tr. The marginal, axial, and occlusal discrepancies of these copings were measured using the silicone replica technique with stereomicroscopy at ×50 magnification, and the data were analyzed with 1‐way ANOVAs (&agr;=.05). Results. The mean marginal discrepancy values were 85.6 &mgr;m for group Cn, 58.7 &mgr;m for group C, and 47.7 &mgr;m for the Tr group. Significant differences were found among the production protocols in marginal, axial, and occlusal discrepancies (P<.05). Copings fabricated with the aid of digital impressions had significantly fewer marginal discrepancies than those of group Cn (P<.05). Group Tr exhibited the lowest marginal discrepancy, whereas groups Cn and C demonstrated similar axial adaptations (P>.05), and group Tr revealed the lowest axial discrepancy (P<.05). With regard to the occlusal discrepancy evaluation, group Tr had the lowest discrepancy. However, no significant differences was found between groups C and Cn (P>.05). Conclusions. The copings produced with the aid of digital impression systems exhibited better marginal and occlusal adaptation than those of the copings produced with the aid of conventional impression.

Frequency and distribution of early tooth loss and endodontic treatment needs of permanent first molars in a Turkish pediatric population

Objectives: The objective of this study is to evaluate the frequency and distribution of early tooth loss and endodontic treatment needs of permanent first molars in a Turkish pediatric population. Materials and Methods: A total of 7,895 panoramic radiographs taken for routine dental examination at the Department of Oral Maxillofacial Radiology between 2008 and 2012 years were investigated. Two independent specialists evaluated early tooth loss and endodontic treatment needs of permanent first molars using panoramic radiography and patient anamnesis forms. The teeth were classified according to the following data: (a) Missing teeth, (b) teeth requiring extraction, (c) endodontically treated teeth (ETT), (d) teeth requiring endodontic therapy. The data also classified according to four factors: Age group (6-12 and 13-16), gender (boy and girl), jaw (mandible and maxilla) and side (right and left). A Chi-square test was used for statistical analyses. Results: A total of 19,488 and 12,092 teeth were evaluated in the child group and adolescent group respectively. All data were higher in adolescents than children (P < 0.001). For gender factor, only ETT was higher in girls than it was in boys (P < 0.001). For the jaw factor, all data were higher (P < 0.001) in mandible than in the maxilla. For the side factor, no statistical difference existed between right and left. Conclusions: Early tooth loss and endodontic treatment needs of permanent first molars showed variability according to age groups and jaws. When the results were compared according to the side and gender factors, no statistical difference was found (P > 0.05) except with the data of ETT in gender groups.