Tamer Türk

Ondokuz Mayıs Üniversitesi, Djanik, Samsun, Turkey

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Publications (12)13.85 Total impact

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    ABSTRACT: Previous studies have used the right and left sides of the same jaw to compare different force levels, types of movement, and durations of forces. However, the amounts of root resorption have not been compared between the right and left sides after applying the same amount of force. The aims of the study were to quantitatively compare the volumes of the root resorption lacunae between the right and left first premolars to determine whether 1 side can serve as a control to the other and to compare the volumes of root resorption lacunae of the first premolars between the maxilla and the mandible. Forty-four first premolars, orthodontically indicated for extraction from 11 patients (left and right maxillary and mandibular first premolars from each) were moved buccally by using beta-titanium-molybdenum alloy 0.017 × 0.025-in cantilever springs with continuous heavy (225 g) force. After the experimental period, the teeth were extracted under a strict protocol to prevent root cementum damage and then analyzed by using a microcomputed tomography scan x-ray system (1172; SkyScan, Aartselaar, Belgium) and specially designed software (Convex Hull 2D, University of Sydney, Sydney, Australia) for direct volumetric measurements. There were no statistically significant differences in the mean cube root volumes of root resorption craters between the right and left sides (P = 0.18) or between the maxillary and mandibular jaws (P = 0.10). There was also no statistical significance for the interception (P = 0.41), which indicated that the jaw and the side had independent effects. The amount of root resorption on the left and right sides of the jaw were similar in both the maxilla and the mandible. Therefore, for future root resorption studies, it is justifiable to use the split-mouth technique so that teeth from 1 side of the jaw can serve as the controls.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 07/2011; 140(1):e49-52. · 1.33 Impact Factor
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    ABSTRACT: Root resorption is an undesirable consequence of orthodontic tooth movement. The severity is unpredictable, and, despite extensive research, the etiology remains unknown. Torque has been acknowledged as a risk factor for root resorption. The aims of the study were to evaluate and quantify the extent of root resorption after the application of 2.5° and 15° of buccal root torque for 4 weeks. Fifteen patients requiring bilateral extraction of their maxillary first premolars for orthodontic treatment were recruited to the study. By using a standardized experimental protocol, the right and left premolars were randomly subjected to either 2.5° or 15° of buccal root torque. At the end of the 4-week experimental period, the premolars were extracted. A volumetric analysis of root resorption was performed by using microcomputed tomography and measured with specially designed software. Overall, the amounts of root resorption were comparable after the application of 2.5° or 15° of buccal root torque (P = 0.59). There was a significant difference between the 2 force levels only at the apical region (P = 0.034). More root resorption occurred in areas of compression than in areas of tension. The variables of age and sex were not statistically significant. Root resorption was evident after 4 weeks of buccal root torque application. More root resorption was seen at the apical region than at the middle and cervical regions. Higher magnitudes of torque might cause more root resorption, particularly in the apical region. As shown in previous studies, the etiology of root resorption is multi-factorial and cannot be explained by mechanical factors alone.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 04/2011; 139(4):e353-60. · 1.33 Impact Factor
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    ABSTRACT: Orthodontic force duration can affect the severity of root resorption. The aim of this clinical study was to investigate the amounts of root resorption volumetrically after the application of controlled light and heavy forces in the buccal direction for 4, 8, and 12 weeks. The sample consisted of 54 maxillary first premolars in 36 patients (mean age, 14.9 years; 21 girls, 15 boys) who required first premolar extractions as part of their orthodontic treatment. The teeth were allocated into 3 groups that varied in the duration of force application: 4, 8, or 12 weeks. The right or left first premolars were randomly selected to receive 2 levels of forces. A light buccally directed orthodontic force of 25 g was applied to the experimental tooth on 1 side, while a heavy orthodontic force of 225 g was applied on the contralateral premolar. At the end of the experimental period, the teeth were extracted and scanned with the microcomputed-tomography x-ray system. Resorption crater analysis was performed with specially designed software for direct volumetric measurements. Significant differences in the extent of root resorption were found between 4, 8, and 12 weeks of force application (P <0.001), with substantially more severe resorption in the longer force duration groups. The light force produced significantly less root resorption than did the heavy force. After 4, 8, or 12 weeks of buccally directed orthodontic forces applied on the maxillary first premolars, the volumes of root resorption craters were found to be related to the duration and the magnitude of the forces.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 03/2011; 139(3):e279-84. · 1.33 Impact Factor
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    ABSTRACT: The aims of this study were to investigate the effects of two surface-conditioning methods on the shear bond strength (SBS) of metal brackets bonded to three different all-ceramic materials, and to evaluate the mode of failure after debonding. Twenty feldspathic, 20 fluoro-apatite, and 20 leucite-reinforced ceramic specimens were examined following two surface-conditioning methods: air-particle abrasion (APA) with 25 μm Al(2)O(3) and silica coating with 30 μm Al(2)O(3) particles modified by silica. After silane application, metal brackets were bonded with light cure composite and then stored in distilled water for 1 week and thermocycled (×1000 at 5-55°C for 30 seconds). The SBS of the brackets was measured on a universal testing machine. The ceramic surfaces were examined with a stereomicroscope to determine the amount of composite resin remaining using the adhesive remnant index. Two-way analysis of variance, Tukey's multiple comparison test, and Weibull analysis were used for evaluation of SBS. The lowest SBS was with APA for the fluoro-apatite ceramic (11.82 MPa), which was not significantly different from APA for the feldspathic ceramic (13.58 MPa). The SBS for the fluoro-apatite ceramic was significantly lower than that of leucite-reinforced ceramic with APA (14.82 MPa). The highest SBS value was obtained with silica coating of the leucite-reinforced ceramic (24.17 MPa), but this was not significantly different from the SBS for feldspathic and fluoro-apatite ceramic (23.51 and 22.18 MPa, respectively). The SBS values with silica coating showed significant differences from those of APA. For all samples, the adhesive failures were between the ceramic and composite resin. No ceramic fractures or cracks were observed. Chairside tribochemical silica coating significantly increased the mean bond strength values.
    The European Journal of Orthodontics 01/2011; 33(6):667-72. · 1.08 Impact Factor
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    ABSTRACT: Repair of root resorption cavities has been studied under light microscopy, scanning electron microscopy, and transmission electron microscopy. The aim of this investigation was to demonstrate the use of microcomputed tomography (micro-CT) to assist in the identification of the region of interest for light microscopy preparation. This study also qualitatively illustrated the root resorption craters with 4 or 8 weeks of retention after 4 weeks of continuous light or heavy orthodontic force application. Four patients who required bilateral extractions of maxillary first premolars as part of their orthodontic treatment were divided into 2 groups (groups I and II) of 2. The maxillary left and right first premolars were loaded with light (25 g) or heavy (225 g) orthodontic force for 4 weeks. After 4 or 8 weeks of retention, the maxillary first premolars were extracted. The extracted teeth were investigated with micro-CT. By using 3-dimensional images created by the micro-CT, the largest resorption craters on the buccal and lingual sides were identified. Parasagittal sections of these resorption craters were studied histologically under hematoxylin and eosin staining. The use of micro-CT improved the efficiency and accuracy of histologic techniques. Comparatively, less root resorption was repaired by new cementum after heavy orthodontic force application and short retention time. The reparative processes seemed to depend on time, with longer retention time yielding the most amount of repair. Reparative cementum was a mixture of acellular and cellular cementum. Reparative processes seemed to commence at the central part of the resorption cavity and expand to the periphery. Root resorption cavities have the potential to repair regardless of the orthodontic force magnitude. Correlative microscopy with micro-CT and conventional light microscopy adds a new dimension to current root resorption investigation techniques.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 12/2010; 138(6):727-34. · 1.33 Impact Factor
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    ABSTRACT: Orthodontic force magnitude is a primary factor in root resorption. Quantitative studies of root resorption after force application for 4 and 8 weeks have been conducted. In this study, we investigated the root surface topography and the amount of root resorption after the application of controlled light and heavy forces in a buccal direction for 12 weeks. In addition, the amounts of root resorption when controlled light and heavy forces were applied to the maxillary and mandibular first premolars were quantified. Forty maxillary and mandibular first premolars were collected from 10 orthodontic patients (age range, 12.7-18.2 years; mean, 14.3 years). A light buccally directed orthodontic force of 25 g was applied to the experimental tooth on 1 side, and a heavy orthodontic force of 225 g was applied on the contralateral premolar. After 12 weeks of force application, the experimental teeth were extracted and scanned with the microcomputed tomography x-ray system. Resorption craters were analyzed with specially designed software for direct volumetric measurements. The tooth movements produced by light and heavy forces were also measured. There was individual variation in all comparisons. The light force produced significantly less root resorption than did the heavy force. The maxillary first premolars were more likely to suffer from orthodontically induced inflammatory root resorption than the mandibular first premolars (P = 0.036). There was a significant difference between buccal and lingual surfaces (P = 0.003), with greater root resorption on the buccal surface. The distribution pattern of the resorption cavities was greatest in the buccal-cervical, buccal-middle, lingual-middle, and lingual-apical areas in both the light-force and heavy-force groups, corresponding with the pressure zones of tipping movement. The mean amount of tooth movement in the heavy-force group was almost twice as much as in the light-force group. The volume of root resorption craters induced by buccally directed forces for 12 weeks on the maxillary and mandibular first premolars was directly proportional to the magnitude of the force. The maxillary premolars seemed to be more susceptible to orthodontic root resorption than did the mandibular premolars.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 10/2009; 136(4):492.e1-9; discussion 492-3. · 1.33 Impact Factor
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    ABSTRACT: The reparative process of root absorption begins in the periodontium when orthodontic force is discontinued or reduced below a certain level. Our aim was to evaluate cementum repair at 4 and 8 weeks of retention after 4 weeks of continuous light and heavy orthodontic forces. The effects of age, tooth movement, and fluoride exposure were also investigated. Forty patients were recruited and divided into 4 groups of 10. The maxillary first premolars were loaded with either light (25 g) or heavy (225 g) orthodontic force. After 4 weeks of loading, the maxillary left first premolars were extracted as the positive control group, and the maxillary right first premolars were placed in retention for 4 or 8 more weeks before extraction; these were the experimental groups. The extracted teeth were studied with microcomputed tomography. To assess cementum repair, volumetric changes of the resorption craters were measured with specially designed computer software. Tooth movement was also measured on study casts taken before and after the extractions. Root resorption continued for 4 weeks after orthodontic force ceased. The resorptive activity was more pronounced from heavy forces. Passive retention after 4 weeks of light force had the least root resorption crater volume (cube root scale). The total amount of the cementum repaired did not depend on magnitude of orthodontic force or retention time within our parameters (P >0.05). This might indicate concurrence of resorption and repair during passive retention. Most repair seemed to occur after 4 weeks of passive retention following the 4 weeks of heavy forces. The volume of root resorption craters positively depended on tooth movement (P = 0.02) and negatively correlated with chronologic age (P <0.01). Although there was no significant difference in the amounts of repair between groups, root resorption continued for 4 weeks after orthodontic force stopped. Resorptive activity was more pronounced after the heavy forces. The reparative processes were different between the light and heavy forces, with marked individual variations. Repair seemed to become steady after 4 weeks of passive retention following 4 weeks of light force application, whereas most repair occurred after 4 weeks of passive retention following 4 weeks of heavy force application. Root resorption crater volume positively depended on tooth movement and negatively correlated with chronologic age.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 10/2009; 136(3):320.e1-10; discussion 320-1. · 1.33 Impact Factor
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    ABSTRACT: The aim of this study was to measure the rate and the amount of orthodontically induced tooth movement under heavy (300 g) and light (50 g) continuous forces with superelastic nickel-titanium closing coils over a defined time (12 weeks). Fourteen patients who required maxillary canine retraction into first premolar extraction sites as part of their orthodontic treatment completed this study. In a split-mouth design, precalibrated nickel-titanium closing coil springs delivering a force of 300 g or 50 g were used to distalize the canines after an alignment and stabilization period. Intraoral and maxillary cast measurements were made at the beginning of canine retraction (T0) and every 28 days for 84 days (T1, T2, T3) to assess total space closure, canine retraction rate, canine retraction and molar anchorage loss, and canine rotation. Statistical analysis showed that the amount of initial tooth movement (T0-T1) was not related to force magnitude; however, during the T1-T2 and T2-T3 periods, increased amounts and higher rates of tooth movement were found with heavy forces. These significantly increased the rate and the amount of canine retraction, but the adverse effects of loss of canine rotation control and anchorage were concomitantly increased. Light forces provided a greater percentage of canine retraction than heavy forces, with less strain on anchorage. Initial tooth movement would benefit from light forces. Heavier forces tend to increase the rate and the amount of canine retraction but lose their advantage because of unwanted clinical side effects.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 09/2009; 136(2):150.e1-9; discussion 150-1. · 1.33 Impact Factor
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    ABSTRACT: INTRODUCTION: The aim of this study was to measure the rate and the amount of orthodontically induced tooth movement under heavy (300 g) and light (50 g) continuous forces with superelastic nickel-titanium closing coils over a defined time (12 weeks). METHODS: Fourteen patients who required maxillary canine retraction into first premolar extraction sites as part of their orthodontic treatment completed this study. In a split-mouth design, precalibrated nickel-titanium closing coil springs delivering a force of 300 g or 50 g were used to distalize the canines after an alignment and stabilization period. Intraoral and maxillary cast measurements were made at the beginning of canine retraction (T0) and every 28 days for 84 days (T1, T2, T3) to assess total space closure, canine retraction rate, canine retraction and molar anchorage loss, and canine rotation. RESULTS: Statistical analysis showed that the amount of initial tooth movement (T0-T1) was not related to force magnitude; however, during the T1-T2 and T2-T3 periods, increased amounts and higher rates of tooth movement were found with heavy forces. These significantly increased the rate and the amount of canine retraction, but the adverse effects of loss of canine rotation control and anchorage were concomitantly increased. Light forces provided a greater percentage of canine retraction than heavy forces, with less strain on anchorage. CONCLUSIONS: Initial tooth movement would benefit from light forces. Heavier forces tend to increase the rate and the amount of canine retraction but lose their advantage because of unwanted clinical side effects.
    American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 09/2009; 136(2):150.e1-9. · 1.33 Impact Factor
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    ABSTRACT: To present the dentofacial changes produced by mandibular body ostectomy in a female patient, 19 years of age, and the patient's 2-year follow-up records. SUBJECT AND TREATMENT: An increased lower facial height and a prominent chin, Angle Class III molar relationship, edentulous gaps in the first premolar regions of the mandible, with overjet and overbite values of -1 mm were observed. Radiographic evaluations revealed impaction of the maxillary right canine. The treatment plan included leveling and coordination of the arches, extraction of the maxillary left first premolar and the impacted canine, and a "rectangular" body ostectomy of 5 mm. Treatment lasted for 24 months. An increase of ANB was observed. Normal overjet and overbite were established. The posterior movement of the lower lip and soft and hard tissue points B and Pg were observed. No major changes were observed for the dentofacial structures at the 2-year follow-up visit. However, slight spacing at the ostectomy sites was present. The rectangular mandibular body ostectomy might be considered an alternative effective method for the correction of mandibular prognathism, particularly when the posterior occlusion is to remain unchanged and when edentulous gaps in the anterior region of the mandible are present.
    World journal of orthodontics 02/2007; 8(4):367-75.
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    ABSTRACT: The aim of this study was to determine the effectiveness of bonding brackets to ceramic restorations. Sixty feldspathic and 60 lithium disilicate ceramic specimens were randomly divided into six groups. Shear bond strength (SBS) and bond failure types were examined with six surface-conditioning methods: silane application to glazed surface, air particle abrasion (APA) with 25- and 50-microm aluminium trioxide (Al(2)O(3)), etching with 9.6 per cent hydrofluoric acid (HFA), and roughening with 40- and 63-microm diamond burs. Silane was applied to all roughened surfaces. Metal brackets were bonded with light cure composite, then stored in distilled water for 1 week and thermocycled (x500 at 5-55 degrees C for 30 seconds). The ceramic surfaces were examined with a stereomicroscope at a magnification of x10 to determine the amount of composite resin remaining using the adhesive remnant index. The lowest SBS values were obtained with HFA for feldspathic (5.39 MPa) and lithium disilicate (11.11 MPa) ceramics; these values were significantly different from those of the other groups. The highest SBS values were found with 63-microm diamond burs for feldspathic (26.38 MPa) and lithium disilicate (28.20 MPa) ceramics, and were not significantly different from 40-microm diamond burs for feldspathic and lithium disilicate ceramics (26.04 and 24.26 MPa, respectively). Roughening with 25- and 50-microm Al(2)O(3) particles showed modest SBS for lithium disilicate (22.60 and 26.15 MPa, respectively) and for feldspathic ceramics (17.90 and 14.66 MPa, respectively). Adhesive failures between the ceramic and composite resin were noted in all groups. Damage to the porcelain surfaces was not observed. The SBS values were above the optimal range, except for feldspathic ceramic treated with HFA and silane. With all surface-conditioning methods, lithium disilicate ceramic displayed higher SBS than feldspathic ceramic.
    The European Journal of Orthodontics 11/2006; 28(5):450-6. · 1.08 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate the movement of anterior teeth during retraction with a force applied through the assumed centre of resistance (CRe).Twenty-two subjects with a Class I or II malocclusion were included. Each subject had the two upper first premolars extracted, resulting in a symmetrical extraction space of at least 3 mm between the upper laterals and canines. The force was applied through the assumed CRe, located 9 mm gingival to the lateral tooth bracket. To examine the type of anterior tooth movement, 10 parameters were measured. A Wilcoxon test was used to determine the differences between pre- and post-retraction values, and a Mann-Whitney U-test to determine the mean differences between groups. In spite of the force application through the CRe, tipping of the anterior teeth was observed in 19 subjects and parallel movement in three patients. Consequently, the subjects were divided into two groups according to the location of the centre of rotation (CRo). In group 1 (nine cases), the CRo was located coronal to the root apex, and in group 2 (13 cases), apical to the root apex. Both groups showed a significant decrease in inclination (P < 0.01) and posterior crown movement (P < 0.01 for group 1 and P < 0.001 for group 2) of the anterior teeth. A significant posterior movement of the root apex was observed in group 2 (P < 0.001). Significant differences were found between the groups for anterior tooth inclination (P < 0.05) and root apex movement (P < 0.001). The reasons for these differences could not be conclusively determined. Even though experimental studies provide information regarding CRe location, factors such as bone support, root morphology and incisor inclination should be taken into consideration. The observation of tooth movement occurring during treatment and changes in treatment mechanics would be helpful in obtaining desired tooth movement.
    The European Journal of Orthodontics 04/2005; 27(2):196-201. · 1.08 Impact Factor

Publication Stats

45 Citations
13.85 Total Impact Points

Institutions

  • 2011
    • Ondokuz Mayıs Üniversitesi
      • Department of Prosthodontics
      Djanik, Samsun, Turkey
  • 2009–2011
    • University of Sydney
      • Faculty of Dentistry
      Sydney, New South Wales, Australia
    • Sydney Dental Hospital
      Sydney, New South Wales, Australia