Lingual retainer uygulaması için er:Yag lazer ve konvansiyonel etching metotlarının in vitro olarak karşılaştırılması / In vitro comparison of er: Yag laser and conventional etching methods for lingual retainer application

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Kurt, Merve
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Bezmialem Vakıf University
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The stability of the teeth alignment following the orthodontic treatment is important in terms of the success of the orthodontist and the patient's satisfaction. Many different retention devices have been designed for this purpose. One of the most commonly used retention tools is the lingual retainer. There are many methods used for roughening the enamel surface for lingual fixed retainer application. It is a challenge to provide the insulation in conventional etching applications. Any failure in the lingual retainer bonding process increases the potential of the relaps. This sensitivity requirement in the conventional etching technique provides the basis for the development of different applications with laser systems. The steps of washing the surface of the enamel are eliminated with lasers, thus it provides the advantage of preventing the saliva contamination during the roughening process. Shrinkage of the adhesive during polymerisation in the bonding of orthodontic attachements may cause microleakage. Another reason for the formation of microfractures is that the attachements bonded to the surface of the teeth are affected by the chewing forces. Structural deterioration occurs in the adhesive due to chewing forces and microfractures are formed. There are various studies showing that these cracks are permit the mouth liquids penetration. Microleakage also causes weakness of the binding and bacterial penetration. Increased bacterial penetration leads to enamel coloring and decalcification. The aim of this study is to evaluate the effects of Erbium: Yttrium-Aluminum-Garnet (Er:YAG) laser and acid etching methods on the bonding strength, fracture type and amount of microleakage. In this doctoral dissertation study, 132 extracted human incisor teeth were used. The enamel surface was roughened using 37% phosphoric acid and Er:YAG laser. Autopolymerized silicone (Anti-Rutsch-Lack; Wenko, Wensselaer, Germany) was applied to the root surface to simulate human periodontal ligament tissue. Using silicone molds, teeth were embedded in the autopolymerizing acrylic as two teeth in each sample. A two-year aging protocol was applied using chewing simulator and thermal cycler devices to mimic the mouth environment. The teeth designated to undergo microleakage evaluation were separated from each other and placed separately in the acrylic blocks to close the apex. Two layers of nail polish have been applied to the teeth to prevent erroneous paintings. In the precision cutting device, sections were taken so that the mesiodistal direction was parallel to the lingual retainer wire. Microleakage between enamel-adhesive and adhesive-retainer wire from mesial and distal sections with stereomicroscope was recorded with millimetric measurements. For evaluation of bonding strength, the lingual retainer was placed in the Universal tester, perpendicular to the tapered piece, and subjected to a tear test. The data at break moment was recorded on the computer in Newton (N). The recorded values were divided by the total surface area of the adhesives on the two teeth and converted to megapascals (MPa). The evaluation of the ARI score was made by examining the same samples. When the bonding strength data were examined, statistically significant difference was found between the groups which were acid-roughened and laser-roughened. Higher force values in the group with the acid etching were recorded. The adhesive remaining on the tooth surface after fracture was examined with stereomicroscope and scored using the Adhesive Remnant Index (ARI). There was statistically significant difference between the groups. Ruptures in the acid-roughened group were more common among between the adhesive and retainer surfaces, while in the laser group , the breakage occurred more often in the enamel-adhesive interface. There was no statistically significant difference in matter of microleakage when the mesial and distal sides were compared between the enamel-adhesive and adhesive-retainer interfaces. When total microleakage was examined by taking the average of these data, the values measured between enamel and adhesive were found to be statistically significantly higher than those measured between adhesive and retainer.
Thesis (Doctoral)--Bezmialem Vakıf University, Orthodontics Department, Istanbul, 2018
Diş Hekimliği = Dentistry, Asitler = Acids, Benzetim = Simulation, Dental bonding = Dental bonding, Dental stres analizi = Dental stress analysis, Dental sızma = Dental leakage, Fosforik asit = Phosphoric acid, Lazerler = Lasers, Ortodonti = Orthodontics, Yüzey pürüzlülüğü = Surface roughness, Çiğneme = Mastication
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