Search In this Thesis
   Search In this Thesis  
العنوان
Effects of Different Parameters of Diode Laser on Acceleration of Orthodontic Tooth Movement and its Effect on Periodontal Tissue Remodeling During Retention :
المؤلف
El-Kattan, Aya Ehab Soliman.
هيئة الاعداد
باحث / ايه اهاب سليمان القطان
مشرف / مصطفي غيث
مشرف / مني محمد صلاح
مشرف / محمد ابو اليزيد
الموضوع
Orthodontics. Periodontics. Diodes.
تاريخ النشر
2019.
عدد الصفحات
vii, 128, [5] p. :
اللغة
الإنجليزية
الدرجة
الدكتوراه
التخصص
Orthodontics
تاريخ الإجازة
1/1/2019
مكان الإجازة
جامعة القاهرة - المعهد القومى لعلوم الليزر - تطبيقات الليزر الطبية
الفهرس
Only 14 pages are availabe for public view

from 184

from 184

Abstract

Recent studies have demonstrated that low-level laser therapy (LLLT) can accelerate orthodontic tooth movement. However, there is still controversy about the optimum parameters that can cause acceleration. The present study was designed to evaluate the different parameters of LLLT in the acceleration of orthodontic tooth movement and also to evaluate their effect on the relapse tendency of orthodontically treated teeth. The mandibular central incisors (n = 100) of the 50 rabbits were randomly divided into four groups according to the treatment modality: group I, positive control group (n= 30); group II, parameter H laser group (n = 30); group III, parameter L laser group (n = 30); group (N), negative control group (n = 10) without any intervention. Groups I, II and III each contained 15 rabbits and each rabbit had an orthodontic appliance on its two lower central incisors while group N had 5 rabbits that acted as the base line control that didn’t undergo and intervention. The orthodontic appliance used in this study was designed to exert a force of 30 gm (15 gm on each incisor). It consisted of two main parts: 1- Two bands 2- Omega loop welded at the middle of the bands The orthodontic appliance was cemented to the lower central incisors to be activated once only at the beginning of the experiment with no further activations during the experiment. group II received laser with parameter H while group III received laser with parameter L according to a specific protocol. While group I didn’t receive any LLLT. The time line of the experiment was 28 days. Orthodontic tooth movement was done for all rabbits of group I, II and III for 21 days then all the orthodontic appliances were removed and teeth allowed to relapse till day 28 which is the last day of the experiment. All rabbits were photographed every other day to measure the exact tooth movement using computer software. Three rabbits from each group were sacrificed at days 3,7,15,21,2. All rabbits in the three groups were photographed, laser irradiated and sacrificed according to a specific protocol. Assessment was done by: 1- Measurement of the rate of tooth movement 2- Real time PCR 3- Histological sections. The results of the study can be summarized as follows: 1- Rate of tooth movement: - During the period from 0 to 3 days and from 3 to7 days of the study, statistically there was no significant difference between the three groups. - During the period of 7th to 15th days and the period of 15th to 21st days there was a highly significant increase in the rate of tooth movement in group III (L) in comparison with the other two groups. While there was no significant difference between group I and group II. - During the period of relapse (21 to 28 days), statistically there was no significant difference between the three groups although the mean percentage relapse was: group I: 46٪, group II: 46.88, group III: 56٪. 2- Real-time PCR findings: - During the period from 0 to 3 days and from 3 to 7 days of the study, statistically there was a significant increase in the expression of RANKL in group III (L) in comparison with the other two groups. While there was no significant difference between group I and group II. - During the period from 7 to 15 days of the study, statistically there was significant increase in the expression of RANKL in group III (L) in comparison with group I (Positive control). While there was no significant difference between group III and group II or group I and group II. - During the period from 15 to 21 of the study, statistically there was significant increase in the expression of RANKL in group III (L) in comparison with group I (Positive control). While there was no significant difference between group III and group II or group I and group II. 3- Histopathologic findings: The micrographs of the laser groups (II&III) generally showed a notable increase in the number of capillaries and fibroblastic proliferation and very vascular periodontal ligaments than group I. At the tension sites: there was more and earlier osteoid tissue formation and proliferation of osteoblasts and fibroblasts in the laser irradiated groups which is more marked in group III. More collagen formation and new bone formation were obvious. At the compression sites: Huge numbers of osteoclasts and large foci of bone resorption were detected earlier in the laser irradiated groups in comparison with group I. And this was more marked in group III than group II. from the results of this study the following could be concluded: 1- The acceleration of orthodontic tooth movement using LLLT is dose dependent and accumulative. 2- The energy dose per session of 5 J and energy density 2500 J/cm2 used for group III in this study, caused significant acceleration in the rate of tooth movement while the energy dose per session of 10 J and energy density 5000 J/cm2 used for group II didn`t cause neither acceleration nor retardation of orthodontic tooth movement. So the lower parameters used in this study may be considered as an optimum for the acceleration of orthodontic tooth movement. 3- It appeared from the histological sections that LLLT stimulated both osteoblastic and osteoclastic differentiation and activity and increased the vascularity of the PDL in the laser irradiated groups but to a greater extent in group III (L). 4- It can be concluded from this study that LLLT used with optimum parameters can accelerate orthodontic tooth movement via increased osteoclastogenesis that appeared in: the statistically significant increase in RANKL expression, statistically significant increase in the rate of orthodontic tooth movement and the increased numbers of osteoblasts and osteoclasts in group III. 5- Relapse appeared in the three groups, which denoted that a retainer is essential during the retention period. And we can`t depend entirely on LLLT to reduce the relapse. Further investigations are needed to reveal if the use of LLLT can decrease the retention period.