Theses supervised by Prof. Dr. Didem Nalbantgil
12 theses · Yeditepe University
An evaluation on the effect of the MIR appliance on the force resistance and stability of mini screws of different lengths and diameters
The present study aims to investigate the effect of the mini-implant ring (MIR) appliance on force resistance and stabilization when used in vitro with mini screws of different lengths and diameters. A total of 120 TM (Trimed, Ankara, Turkey) mini screws, including 20 pieces of 1.4 mm diameter and 6 mm length, 20 pieces of 1.4 mm diameter and 8 mm length, 20 pieces of 1.6 mm diameter and 6 mm length, 20 pieces of 1.6 mm diameter and 8 mm length, 20 pieces of 1.8 mm diameter and 6 mm length, and 20 pieces of 1.8 mm diameter and 8 mm length were used for the study. Titanium TM mini screws with a conical structure and "self-drilling" feature were preferred in the study. The other group in which the MIR was not applied was used as the control group. Mini screws were applied to samples obtained from bovine hip bones, in the laboratory using a torque screwdriver (N2DPSK, Nakamura MFG Co Ltd, Tokyo, Japan) and maximum application torque (MAT) values were measured. Then, by applying force perpendicular to the long axis of the mini screw with an Instron tester, the resistance values of the mini screws up to a 0.6 mm displacement were recorded. Following the evaluation of the mobility of the force-tested mini screws, the mini screws were removed from the bone by measuring their maximum extraction torques (MET) with a torque meter screwdriver. The statistical analysis showed that application torques increased in mini screws to which the MIR appliance was applied, and this increase did not exceed desired levels. A nonsignificant increase in extraction torques was also recorded. These results show that the MIR apparatus is effective in increasing the force resistance and stability particularly of smaller diameter mini screws to a certain extent. As a result of the research, the MIR apparatus is recommended as a good option, especially in cases where the cortical bone is thin or a smaller diameter mini screw is preferred, since it increases the primary stability and force resistance of the mini screw. Keywords: Mini screw, MIR appliance, stability, force resistance, screw diameter, screw length
Histomorphometric and biochemical evaluation of the effects of different molecular weight hyaluronic acid on bone formation in rats
The aim of this study was to evaluate the histomorphometric and biochemical effect of locally applied hyaluronic acid solution with different molecular weight on bone formation in the long and short term, injection applied into the midpalatal suture area in rats. This study was conducted on 48 male Sprague-Dawley rats with an average weight of 360,31±52,2 gr.The rats were divided into 3 groups; control (saline application only), LMWHA (low molecular weight hyaluronic acid), HMWHA (high molecular weight hyaluronic acid). Two different time intervals were examined for each group: 10th and 20th days groups after injection. In all groups, rats maxillas were expanded with stainless steel helix expansion spring. On the 5th day, helix spring was removed and replaced with retention wire. Simultaneously with retention procedure, 0,05 ml (50 μl) high and low molecular weight hyraluronic acid and saline solution was locally injected to midpalatal suture area. After the 10th and 20th day of injection rats were sacrified. Blood samples were collected and upper jaw samples were dissected and prepared for histological examination. For histomorphometric examination, dissected and trimmed blocks were longitudinally sectioned serially, 10 μm thickness intervals were applied parallel to long axis of the incisors. The sections were stained with Masson's trichrome were analyzed by photo microscope. Bone and connective tissue volume measurements were made. Blood serum plasma were obtained from blood samples by centrifugation, and the amount of HA (hyaluronic acid) in the serum was determined using HA measurements kits. Bone formation amount showed a significant difference between the control and experimental groups on the 10th and 20th days (p<0,05). Bone area (m2), and bone perimeter (m) and blood serum HA values of each group were examined. As a result of histomorphometric examination, high molecular weight hyaluronic acid solution significantly increased bone formation in the long and short term compared to low molecular weight hyaluronic acid and control groups (p<0,05). Also low molecular weight HA groups showed significantly high bone formation values according to control groups (p<0,05). When blood serum HA levels were examined, LMWHA groups showed high values but there was no significant difference between the blood serum HA values of experimental and control groups (p> 0,05). In this study, it was aimed to accelerate bone formation, shorten orthodontic retention time and decrease relapse with a minimally invasive approach, and also aimed to elucidate the systemic spread characteristics of locally applied HA solutions by analyzing to blood serum HA data biochemically. Bone formation is increased by local application of high and low molecular weight hyaluronic acid. This study shows that, local injection of HMWHA and LMWHA solution in midpalatal suture area after rapid maxillary expansion stimulated new bone formation that may shorten retention time and may reduce the risk of relapse. Key words: Rapid maxillary expansion, hyaluronic acid, accelerated bone formation, orthodontic relapse, blood plasma, rats
Examination of the effects of skeletal-borne and soft tissues-borne intraoral molar distalization methods
The aim of our retrospective study is to evaluate the dental effects of the Palatally mini-screws assisted molar distalizer (study group ) and comparing it with the soft tissues supported pendulum appliance ( control group ). 12 cases were collected from the archive of Orthodontic Department of Yeditepe University for each group. Cephalometric radiographs with metal guide and 3D models has been taken before and after the distalization process for each case were collected and evaluated. The mean age of the patients was 15.7 years old for both groups. There was no significantly difference with the average of the distalization period between both the control and the study groups. The upper molar distalization amount of the control group was significantly higher than the study group. Also The upper premolars and canine had a significant mesial shift in the control group while it had a significant distal shifting in the study group (p<0.01). The amount of the distal tipping of the upper first molar in the control group was significantly higher than the study group (p<0.01). Also the upper second and first premolars had a significantly mesial tilting in the control group while it had a significant distal tipping in the study group (p<0.01 ). Moreover, the upper first molar had a distobuccal rotation in the control group while it has shown mesiobuccal rotation in the study group (p<0.01). A significant labial tipping had been shown with the upper incisors in the control group (p<0.01), while unsignificant change in the study group (p>0.05).
The effects of light and vibration aplication on aligner treatment duration cases with lower crowding of mandibular incisors
The aim of this study is to evaluate the effects of lights and vibration on aligner treatment duration cases with lower crowding of mandibular incisors. There are invasive and non-invasive methods for accelerating orthodontic tooth movement. There is a tendency for both clinicians and researchers to focus on accelerating methods for orthodontic tooth movement due to the huge demand for adults for a shorter orthodontic treatment time such as medicines, led light force, low level of laser theraphy, photo biomodulation, surgical methods, corticotomy, piezocisions, decortication or micro-osteoperforation, combination of led light and vibration, bracket systems or digital methods. With this study it was also desired to create a more conservative technique to accelerate tooth movement than those other methods, which would easily be accepted by the patients and have continuous effects throughout the desired period of the treatment.In this retrospective study, a total of 89 patients who applied to Yeditepe University Faculty of Dentistry Department of Orthodontics were included in the study. Patients were assigned to four groups. First group which included 19 (11 female, 8 male) patients was the control group. Second group with 26 (14 female, 12 male) patients received a 30 Hz 25 N vibration device, third group which had 21(12 female, 9 male) patients received a device which produced 850 nm LED light and the last group consisting of 23 (14 female,9 male) patients got a device which combined vibration and light features. All patients with devices were asked to use them 20 minutes daily. At the initial appointment (T0), at 28 days later (T1), at 48 days later (T2), and 62 days later(T3) impressions were taken to produce dental casts. The tooth movements of the patients were recorded measuring the differences in amounts of crowding. According to measuring on 62 nd day; there is no statistical differences between control group and neither photo biomodulation group nor vibration group. A significant increase in speed of tooth movement speed was observed in the HOT group (p<0.05). The treatment done with clear aligners and the combination of light and vibration might be an effective method in accelerated orthodontic tooth movements. Key words: Clear Aligners, Vibration, Photo-biomodulation, Accelerated Tooth Movement
In vitro evaluation of microleakage under lingual brackets bonded with different adhesion materials and different light sources
The aim of this research is to evaluate the microleakage under standart orthodontic brackets (sia easy orthodontic brackets bonded with three adhesive systems, and two light curing units.72 extracted bovine incisors were divided randomly into six groups. All of these groups were preconditioned with air abrasion. Three adhesives were used to bond the brackets to enamel: 37% phosphoric acid+Transbond XT Primer+Transbond XT Adhesive, Maxcem Elite and Nova Compo SF. Elipar S10 Curing Light and Valo Ortho Curing Light were used to polymerize the adhesives. The specimens were stained with 0.5% basic fuchsine solution, sectioned buccolingually and evaluated under microscope (20x magnification) at enamel-adhesive and bracket-adhesive interfaces from gingival and incisal margins. Microleakage was observed in all groups. There was no significant difference between microleakage scores of gingival and incisal margins (p>0.05) or microleakage in enamel-adhesive (p=0.004) and bracket-adhesive interfaces (p=0.0001). Regardless of the curing unit, adhesive type does not have a significant effect on microleakage. According to the analysis results there is no statistically significant difference was found between the microleakage measurements in terms of the adhesive type used. However the microleakage averages obtained from the measurements using Total Etching (Transbond) are lower than the measurements using Self Etching Keywords: microleakage, orthodontics, brackets, self-etching, one step adhesive, air abrasion
In vitro evaluation of shear bond strength of orthodontic brackets with different adhesives
The aim is to evaluate the shear bond strength of stainless-steel orthodontic brackets bonded with two different adhesive systems. Sixty extracted bovine incisors were divided randomly into three groups. To bond, the brackets to the enamel surface used two different methods: 37% orthophosphoric acid+Transbond XT Adhesive+Transbond XT Primer, BracePaste Adhesive+BracePaste Primer, and only BracePaste Adhesive. Valo Ortho Curing Light was used to polymerize the adhesive materials. After polymerization, the specimens were measured for the shear bond strength on the universal testing machine. Transbond XT Adhesive+Transbond XT Primer group showed a mean SBS of 11.73 ± 1.74 MPa, BracePaste Adhesive + BracePaste Primer group a mean SBS of 11.11 ± 1.51 MPa. There is a statistically significant difference between the shear bond strength scores of BracePaste Adhesive + BracePaste Primer and BracePaste Adhesive without BracePaste Primer. BracePaste Adhesive without BracePaste Primer group showed a mean SBS of 2.42 ± 0.81 MPa. There is a statistically significant difference between the mean shear bond strength of BracePaste Adhesive+ BracePaste Primer and BracePaste Adhesive (p=0.0001). There is no statistically significant difference between the mean shear bond strength of Transbond XT Adhesive+Transbond Primer and BracePaste Adhesive+BracePaste Primer (p=0.357). In conclusion, our study indicates no statistically significant difference between the mean shear bond strength of Transbond XT and BracePaste Adhesive with BracePaste Primer. Furthermore, we found a statistically significant difference between the mean shear bond strength of BracePaste Adhesive with BracePaste Primer and BracePaste Adhesive without BracePaste Primer.
Comparison of the mechanical properites of three-dimensionally printed orthodontic models with different materials and infill parameters
In this study, our purpose was to collect data by comparing the effect of the compressive strength on two different polymers, in order to reduce the time and the cost of 3D orthodontic model printing. Our specimens are produced from 'Esun ABS+' brand filament (Acrylonitil, 1-3, butadiene styrene) printed in 'Creality Ender-3 S1 Pro' brand FDM printer and 'Anycubic standard 3d printing resin (1-methyl-1,2ethanediyl) bis[oxy(methyl-2,1-ethanediyl)] diacrylate printed in 'Anycubic Mono X' brand DLP type printer. In our research, two different printing materials ABS and Resin are the two main groups. The subgroups of these two main groups were designed in 'UltiMaker Cura' software as rectangular prisms which are designed as 30%, 60%, 80 % and 100% infill patterns. Printing was carried out with ten samples for each subgroup. With the power analysis, 'G*power 3.1'each group's sample size was planned to be 10. The plastic deformation values of the samples were recorded on the Instron Universal Testing machine. All groups were compared with each other, and the results were statistically analyzed. Between the maximum load averages in the compressive strength of the groups with the 80 % and 100% infill ratio no statistically significant difference was observed. (p=0.097 for ABS, p=0.092). Except this one, between all the other groups statistically significant differences have been observed (p<0.05). As compressive force applied when printing clear aligners is about 0.4 MPa, all groups have enough compressive strength for the 3D orthodontic model production. When 30% infill subgroup was compared with all the other subgroups, statistically significant difference was observed (p<0.05). Similar studies should be conducted in groups with an infill rate below 30% in future research.
Examination of microleakage on different orthodontic retainers under simulated Gastroesophageal Reflux Disease (GERD) – an in-vitro study
The aim of this study is to evaluate the microleakage on two different orthodontic retainers under simulated gastroesophageal reflux disease. While bonding the retainers, the impact of two different bonding materials with the effect of the previous air abrasion of the enamel to the microleakage will also be observed. 144 extracted bovine incisors were divided randomly into sixteen groups, each group containing 9 samples. Eight of these groups were preconditioned with air abrasion. Two different adhesives ( 37% phosphoric acid + 3M Transbond XT primer + 3M Transbond LR adhesive and 37% phosphoric acid + Transbond XT primer + 3M Flowable Composite ) were used to bond two different types of retainers ( braided retainer wire of .10×.028-inch 6" length and ss multi-strand wire with co-ax straight length 0215 14"). Elipar S10 curing light was used to polymerize these adhesives. After the bonding procedure, the speciments were subjected to 2 different immersion regimens. While the eight of the groups were immersed in simulated gastric solution of pH 1.5, the other half of the groups were immersed in the artificial saliva with pH 7. Immersion regimes were carefully carried out for 8 days; each immersion lasting for five minutes. The regime was distributed over a 12-hour period. At the end of immersion period, all the tooth surfaces except 1 mm wide zone around the margins of the bonded retainer were painted with nail varnish. After the nail varnishing process is done to the all samples, they were immersed in 0.5% basic fuchsine solution for 24 hours at room temperature. Afterwards the specimens were sectioned parallel to the lingual retainer wire with a dental diamond saw (Meisinger, Neuss, Germany) and evaluated under microscope (20x magnification) at enamel adhesive interfaces from mesial and distal margins. Microleakage was observed in all groups. There was no significant difference between microleakage scores of mesial and distal margins (p >0.05). There was no statistically significant difference between two different orthodontic retainer types microleakage scores in any of the groups at the p<0.05 significance level. Among all groups, the microleakage score of the group immersed in the solution of pH 1.5 showed statistically significantly higher result than the group which is exposed to a solution of pH 7. The acidity of the pH solution increased the microleakage score. The microleakage score of the group which has not gone under a previous air abrasion of the enamel showed statistically significantly higher result than the group which has undergone a previous air abrasion of the enamel. Among the adhesive systems which were used, it was found that all of the groups which have undergone to an immersion to pH 1.5 have not shown any statistically significant result with microleakage. When the speciments were immersed in the solution of pH 7, the adhesive systems showed statistically significant results with their microleakage scores. The flowable composite exposed higher microleakage score than the Transbond LR composite. Keywords: microleakage, retainers, air abrasion, adhesives, GERD
3D evaluation of nasomaxillary complex after orthognathic surgery
This retrospective study aimed to evaluate the nasomaxillary soft tissue changes of skeletal class III patients with LeFort I before and after orthognathic surgery and compare the changes according to various parameters. The study comprised 27 patients, 8 (%29.6) men and 19 (%70.4) women, aged between 20 and 42. The amount of maxillary advancement was between 1-5 mm in 14 (51.9%) patients and 5.5-10 mm in 13 (48.1%) patients. 16 (59.3%) patients had a high-angle growth pattern and 11 (40.7%) patients had a low-angle growth pattern. 3D stereophotogrammetric recordings of the individuals in the study were taken before (T0) and approximately six months after surgery (T1). Measurements were made on 3D facial photographs and statistical analyses were applied. In the 1-5 mm and 5.5-10 mm advancement groups, the increase in alar width, alar base width, and labiale superius projection; the decrease in nostril show was found to be statistically significant at T1 time compared to T0 time (p<0.05). In the 5.5-10 mm advancement group, the upper lip-E line decrease was statistically higher than the 1-5 mm advancement group at T1 time compared to T0 time (p<0.05). From T0 to T1, the high-angle group had a significantly higher increase in upper lip-E line and lip length measurements than the low-angle group (p<0.05). In the 5.5-10 mm advancement group and the high-angle group, the decrease in nasofrontal angle was statistically significant at T1 compared to T0 (p<0.05). As a result, significant changes were found in the nasomaxillary region in patients who underwent maxillary advancement. Stereophotogrammetry device allows 3D evaluation of soft tissues.
Examination of corrosion effects on orthodontic brackets under simulated gastroesophageal reflux disease (GERD) – an in-vitro study
The aim of this study was to investigate the surface roughness and ion release of stainless steel brackets (N=180, upper central incisor) after corrosion under simulated Gastroesophageal Reflux Disease. The effects of different pHs and durations were evaluated. Brackets were randomly divided into 3 main groups and 15 subgroups (n=12). The pH solutions forming the main groups were: simulating severe (pH 1.5) and moderate (pH 3.0) forms of gastric regurgitation and artificial saliva (pH 7.0) as the control group. Each pH group was divided into subgroups according to the brackets' elapsed times in the solutions (30 minutes, 12 hours, 24 hours, a week, a month). All of the specimens were kept in an incubator, at specified times. The average surface roughness of bracket slots was examined with optical profilometer. Inductively coupled plasma mass spectrometry (ICP-MS) was used to determine the metal ions (Fe, Ni, Cr) released to the solutions from brackets. Before immersions, initial surface roughness (ISR) of each braket slot was measured. After immersions, final surface roughness (FSR) and the difference of FSR-ISR of each bracket slot were examined, and the results were compared statistically in all main pH groups and time subgroups. Also, ion release at 30 minutes, 24 hours and 1 month were examined and the results were compared statistically in all main pH groups and specified time subgroups. When the pH groups were evaluated in terms of FSR at different time intervals, the statistically significant difference in all pH groups firstly occured after 24 hours (p=0.0001). The FSR-ISR was statistically significant in all main pH groups and time subgroups (p=0.0001). As the acidity of the environment and the immersion time increased, increased corrosion of brackets was observed. The highest FSR, FSR-ISR and ion release were found in pH 1.5 group at 1 month. pH 7.0 group's ion release at all time subgroups (except 30 minutes for Ni) was found to be lower than gastric solutions. Ion release from the brackets occurred in all pH groups at all time intervals, but the amounts of ion release were below the toxic limits.
Effects of adipose-derived mesenchymal stem cells on bone formation and stability of orthodontic mini screw implants.
The aim of this randomized controlled experimental animal study was to evaluate the differences between the stability of Stem cell (SC)- treated orthodontic mini screw Implants (MSIs); with or without Boron versus non-Stem cell treated groups under different force levels and to assess the bone formation around those mini implants. 15 New Zealand white adult male rabbits were randomly divided into three groups as; stem cell, stem cells+boron and control. 77 titanium customized orthodontic miniscrews (Osmed Dental, Istanbul, Turkey) with a length of 6 mm and a diameter of 1.4 mm were implanted in each proximal tibia and different force levels (0, 150, and 300 cN) were applied to each group. In a 21-day retention period, the implant stability was assessed by resonance frequency analysis (RFA) and Implant Stability Quotient (ISQ) values were measured by Osstell device (Integration Diagnostics AB, Göteborg, Sweden). At the end of the study MSIs were evaluated 3 dimensionally with micro Computed Tomography (µCT); (SkyScan 1172; Bruker Cooperation, Kontich, Belgium). Descriptive statistics were performed for the statistical analysis. Since the data were not normally distributed, non-parametric tests were used. All baseline values and sub-group differences were compared by Kruskal-Wallis test. The data revealed that primary stability of all miniscrews was similar in all groups under 0 cN (p = 0.135), 150 cN (p = 0.779), and 300 cN (p = 0.498) force levels at the start of the experimental procedure. At the end of the study no statistically significant changes were determined in ISQ values of any force groups, under 0 cN (p = 0.057), 150 cN (p = 0.893), and 300 cN (p = 0.972) force levels. µCT findings suggest that Bone Volume to Tissue Volume (p = 0.053), Bone Surface to Bone Volume (p = 0.061), Trabecular thickness (p = 0.061), Trabecular number (p = 0.099), Trabecular separation (p = 0.159), closed porosity (p = 0.097) and open porosity (p = 0.098) value changes were not statistically significant in 3 main groups. Key Words: Stem Cells, Mini Screw Implants, Bone Formation, Mini Screw Stability, Boron
In-vitro evaluation of microleakage under orthodontic brackets bonded with various adhesive systems
The aim is to evaluate the microleakage under orthodontic brackets bonded with three adhesive systems, different surface preparations, and two light curing units. 144 extracted bovine incisors were divided randomly into twelve groups. Six of these groups were preconditioned with air abrasion. Three adhesives were used to bond the brackets to enamel: 37% phosphoric acid+Transbond XT Primer+Transbond XT Adhesive, Transbond Plus Self-Etching Primer+Transbond XT Adhesive and 37% phosphoric acid+GC Ortho Connect. Elipar S10 Curing Light and Valo Ortho Curing Light were used to polymerize the adhesives. The specimens were stained with 0.5% basic fuchsine solution, sectioned buccolingually and evaluated under microscope (20x magnification) at enamel-adhesive and bracket-adhesive interfaces from gingival and incisal margins. Microleakage was observed in all groups. There was no significant difference between microleakage scores of gingival and incisal margins (p>0.05). When air abrasion was applied, the type of adhesive did not have a significant effect on microleakage. When enamel was not preconditioned with air abrasion, GC Ortho Connect showed more microleakage in enamel-adhesive (p=0.004) and bracket-adhesive interfaces (p=0.0001). Air abrasion caused more microleakage when brackets were bonded with Transbond XT Primer (p<0.05) and Transbond Plus Self-Etching Primer (p=0.0001). Valo Ortho Curing Light caused more microleakage when Transbond XT Primer was used without air abrasion preconditioning (p=0.0001). Regardless of the curing unit, adhesive type does not have a significant effect on microleakage, when air abrasion preconditioning. When the enamel is not preconditioned with air abrasion, one step adhesive system causes more microleakage than the conventional and self-etching adhesive systems. Keywords: microleakage, orthodontics, brackets, self-etching, one step adhesive, air abrasion