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INTRODUCTION: Tooth bleaching has proven to be a conservative esthetic solution for tooth discoloration, hydrogen peroxide (HP) is used as an active oxidizing agent for tooth whitening; it can be used either directly or indirectly by chemical reaction from carbamide peroxide (CP). So many patients suffer from discomfort and sensitivity during and after the bleaching procedure. The use of fluoride shows to be beneficial in reducing the adverse effects of bleaching on Enamel.OBJECTIVES: The study was designed to evaluate the effect of fluoride incorporation in bleaching agents on enamel surface properties.MATERIALS AND METHODS: twenty sound human premolars extracted for orthodontic reasons were selected for the study. The selected premolars were randomly divided into 2 equal groups (10 teeth per group) as follows:Study Group I: The teeth were bleached using 10% Carbamide peroxide.Study Group II: The teeth were bleached using 10% CP containing 0.11% fluoride.All the specimens were examined by scanning electron microscopy (SEM) and micro-hardness test.RESULTS: after 14 days erosion pattern was noted in teeth from group 1 while the teeth of group 2 showed milder demineralization, group 1 showed significant decrease in micro-hardness compared to the base line whereas group 2 teeth that were treated with fluoridated bleaching agent showed insignificant reduction in micro-hardness.CONCLUSIONS: incorporation of fluoride in bleaching agents reduces the adverse effects of bleaching on the enamel surface.

IntroductioN: Low-level laser therapy (LLLT) has been studied in many fields of dentistry due to its reparative and anti-inflammatory effect. Regarding the orthodontic tooth movement, LLLT accelerates tooth movement, reduces the pain, enhances bone remodeling and reduces the orthodontic inflammatory induced root resorption (OIIRR). ObjectiveS: The aim of the present study was to assess histologically and histomorphometrically the effect of LLLT on OIIRR under heavy orthodontic force magnitude (50 g) in rat model. Materials and methodS: Sixteen male Albino rats weighing from (250-300 g) were randomly assigned to two equal groups (8 rats each). Control heavy-force group (CH): the maxillary right first molars were subjected to orthodontic force of 50 g by placement of a coil spring. Laser high-force group (LH): the maxillary right first molars were subjected to orthodontic force of 50 g + LLLT at four points (two buccal and two palatal), 12 seconds per point, with a GaAlAs diode laser source irradiated with the dose of 4.8 J/cm2 (100 mW, 12 s, 0.6 J) on every other day during force application. The rats were sacrificed after 21 days of orthodontic force application. After sacrificing the rats; the maxillae were hemisected and serial sections of the area of maxillary right first molar were obtained and evaluated histologically and histomorphometrically. ResultS:Root resorption was significantly decreased (p=0.001) in laser group (L) in comparison to the control group (C). In contrast, root resorption was the largest and deepest up to the dentin in the control group. Moreover, odontoclasts were observed especially in the C group indicating still active root resorption activities. In addition, increased blood vasculature and formation of reparative cementum layer covering the resorption lacunae were observed in the Laser group. ConclusionS: LLLT seems promising in preventing or reducing orthodontic root resorption, in addition to accelerating and enhancing the healing and repair of OIIRR.

INTRODUCTION: Significant development has been achieved with bioceramics and biopolymer scaffolds in the construction of artificial bone. In the present study, Chitosan– nanohydroxyapatite (CS/nHA) scaffolds have been developed as bone graft substitutes in rabbits with induced osteoporosis.OBJECTIVES: To evaluate the effect of Chitosan- nanohydroxyapatite (CS/nHA) scaffold in bone tissue regeneration of extracted socket in rabbits with induced osteoporosis; using Scanning Electron Microscope and Energy Dispersive x-ray analysis [EDXA].MATERIALS AND METHODS: Twenty NewZealand white female rabbits were randomly divided into 2 equal groups; group A (osteoporosis) with no graft material, and group B (osteoporosis with CS/nHA). After the experimental period the animals were sacrificed at 2 & 4 weeks. The effect of CS/Nha was evaluated using Scanning Electron Microscope and Energy Dispersed x-ray analysis [EDXA]. The data obtained was tabulated and subjected to statistical analysis.RESULTS: Scanning Electron Microscopic results revealed more trabecular bone thickness with regular bone surface, and uniform osteocyte lacunae in the group B (osteoporosis with CS/nHA) than group A (osteoporosis), and these results were proved by EDXA which showed more Ca and P ratio in the group B than group A.CONCLUSIONS: CS/nHA scaffold is considered an effective hard tissue engineering material with sufficient interconnected porosity and mechanical strength to allow cell adhesion, migration, growth and proliferation resulting in good integration with surrounding tissues, and rapid bone healing, thus it might be used in osteoporotic condition.

INTRODUCTION: Critical sized bone defects above critical size do not heal completely by themselves and thus represent major clinical challenge to reconstructive surgery. Numerous bone substitutes have already been used to promote bone regeneration. Incorporation of bone grafts such as biphasic calcium phosphate (BCP) as osteoconductive materials has been proven to be effective in promoting bone healing in oral surgery. As it is considered a potential candidate for bone regenerating biomolecules which can help in rapid bone repair because of its composition, the biocompatible material "mineral trioxide aggregate"(MTA) is suggested to be promising. OBJECTIVES: To compare the efficacy of MTA on the process of bone healing alone and the combination of MTA with biphasic calcium phosphate MATERIALS AND METHODS: Sixteen rabbits will be divided into two experimental groups: (1) MTA, (2) MTA+BCP. Right and left critical size bone defects will be performed in the edentulous area of rabbit mandibles (diastema). Right side bone defects will be filled with MTA, while the left side bone defects will be filled with MTA in combination with BCP. The effect of both MTA and BCP on defect healing will be assessed histologically, histomorphometrically and immunohistochemically after 6 weeks postoperatively. RESULTS: Greater amount of new bone formation was noticed in the CSDs loaded with MTA and BCP. The amount of new bone formed was significantly higher in the MTA+BCP group when compared with the MTA group. Also bone cells activities appeared greater in the former group. CONCLUSIONS: MTA induces new bone formation via an osteoinductive action and can be added to bone grafts to enhance bone regenerative capacity

INTRODUCTION: Depression is one of the most prevalent psychological disorders. It affects all body systems including endocrinal,neurological and immune system. Additionally, it is thought to affect bone homeostasis. Antidepressants are the most commonly prescribeddrugs. They are classified into tricyclic and tetra cyclic antidepressants (TCAs), monoamine oxidase inhibitors (MAOIs) and selectiveserotonin-reuptake inhibitors (SSRIs). Fluoxetine, which is a selective serotonin-reuptake inhibitor, is used for the treatment of depression byselectively acting on serotonin (5-HT). Fluoxetine plays a major role in bone apposition and in maintaining the bone homeostasis.OBJECTIVES: To investigate the effect of selective serotonin-reuptake inhibitor (fluoxetine) on the structure of alveolar bone in rats withinduced depression.MATERIALS AND METHODS: Thirty adult male rats were divided as follows: Group I: (control group) which consists of 10 rats, Group II: (depression group) 10 rats were exposed to chronic unpredictable stress (CUS) to induce depression, Group III: (fluoxetine group) 10 ratswere exposed to chronic unpredictable stress (CUS) to induce depression and at the same time they were orally supplied with 10 mg/kg/day offluoxetine. After 3 months, the mandibles were dissected out and prepared for histological analysis using light microscope, scanning electronmicroscope (SEM) and energy dispersive x-ray microanalysis (EDX).RESULTS: In the control group, the alveolar bone surface showed a regular and smooth outline. In the depression group, there was a significantdisturbance in the bone architecture. The bone surface showed an irregular outline with multiple osteoclasts lying in How ship's lacunae. Deeplystained incremental lines were also evident. In the fluoxetine group, the bone surface restored its regular outline with multiple osteoblasts andosteocytes. The bone showed incremental lines indicating bone formation.CONCLUSIONS: Depression can lead to bone loss and osteoporosis. Fluoxetine is an effective drug in enhancing the bone condition andrestoring the normal architecture of the alveolar bone.

INTRODUCTION: Avulsion of teeth radically affects the integrity of the tooth and the supporting tissue, and impairs the natural dentition as a whole; thus, all efforts must be directed to the replantation of traumatically avulsed teeth. However, its success is limited due to the occurrence of external root resorption. The challenge is to follow an effective protocol that reduces the occurrence of root resorption and allow for reestablishment of the natural architecture of the periodontal tissue. Biomodulation provided by low level laser therapy provides a promising tool in managing the inflammatory process and augmentation of the reparative process. OBJECTIVES: Was to evaluate the effect of low-level laser therapy (LLLT) on the healing process of rat teeth replanted after delayed replantation. MATERIALS AND METHODS: Thirty healthy Albino male rats had their maxillary left incisors extracted; According to the root surface treatment before the replantation, the teeth were assigned randomly to two groups (n = 15): G1 (control) – no root surface treatment; G2 (study group)-laser diode treatment on the root surface. The teeth were replanted into their respective sockets after 30 minutes, mimicking the natural timing it would take to replant an avulsed tooth. G2 were treated with LLLT performed on the buccal and palatal mucosa every 48 hours for 15 days. The rats were sacrificed after 15, 30 and 45 days of replantation. The specimens were processed for histological and histomorphometric analysis to determine the average root resorption areas and to evaluate the histological events. RESULTS: Histomorphometric analysis showed that the study group (Laser irradiated group) showed lower areas of root resorption and ankylosis, than in control group (non-irradiated group); with a significant statistical difference (p > 0.05). Histological assessment showed restoration of periodontal ligament attachment and increased vascularity in the study group. CONCLUSIONS: Laser irradiation reduces external root resorption and ankylosis in delayed tooth replantation.

Introduction Maintaining tooth anchorage during orthodontic treatment has challenged orthodontists and threatening the success of some orthodontic therapy. The objective of this study was to evaluate the effect of local administration of simvastatin on orthodontic tooth movement. Methods Nickel-titanium coil springs were used to induce orthodontic tooth movement in 10 white New Zealand rabbits for 21 days. A split-mouth design was implemented where one mandibular quadrant received local administration of simvastatin and the corresponding mandibular quadrant received control vehicle solution on a weekly basis. Magnitudes of tooth movement were measured on 3-dimensional models of the experimental teeth. Animals were killed at the end of the experimental period to allow histomorphometric analysis of alveolar bone modeling. Results The total magnitude of tooth movement in the quadrant receiving simvastatin was significantly less than that in the quadrant receiving control vehicle solution. Local administration of simvastatin resulted in a significant percentage of inhibition of tooth movement of 39.8 ± 22.6%. Histomorphometric analysis revealed a significant reduction in the numbers of osteoclasts and areas of active bone-resorptive lacunae hindering bone resorption processes in the quadrant receiving simvastatin. Conclusions Local administration of simvastatin can reduce the rate and magnitude of orthodontic tooth movement. Moreover, local administration of simvastatin diminishes bone resorption processes associated with orthodontic tooth movement reducing the number of osteoclasts and the subsequent area of active bone resorption.

Introduction: Lepidium sativum, commonly known as garden cress is a herb that is native to Egypt and West Asia. Its seeds are rich source of proteins, dietary fiber, omega-3 fatty acids, iron, other essential nutrients and phytochemicals. Garden cress is widely used in folk medicine for the treatment of many diseases. Periodontitis is defined as an inflammatory bacterial-induced disease that damages the soft tissue and gradually destroys the periodontal ligaments and supporting alveolar bone. Periodontitis can cause teeth to loosen or lead to tooth loss. Different methods, such asbiomechanical measurements, surgical approaches are used to treat periodontitis. Objective: to evaluate histologically and ultra-structurally the possible effect of garden cress therapy on alveolar bone healing in rats with ligature induced periodontitis. Materials and Methods: Fortyfive adult male Sprague–Dawley rats of 6 months old (200-250 grams in weight) was used in this study. They were divided into 3 equal groups: group A; (control group), group B; (ligature induced periodontitis) and group C :( ligature induced periodontitis with garden cress administration). Ligature was removed after 11 days. Garden cress was applied after ligature removal systemically by using oral gavage. Rats were sacrificed after six weeks from the ligature removal. Mandibles were dissected out and were prepared for histological and scanning electron microscopic evaluation. Results: After 6 weeks the specimens of group B (periodontitis group) showed alveolar bone loss, while in group C (garden cress group) showed relative restoration of alveolar bone. Results of scanning electron microscope revealed an irregular & porous bone surface of group B, while Group C showed relative smooth and regular alveolar bone. Conclusion: Garden Cress systemic administration accelerates alveolar bone healing and enhances bone formation in periodontal diseases.

INTRODUCTION: Bone defect above critical size does not heal completely by itself and thus represents major clinical challenge to reconstructive surgery. Tissue engineering is a new approach for the repair of osseous defects. β tricalcium phosphate (β-TCP) loaded with autogenous bone marrow derived mesenchymal stem cells (BMSCs) is suggested to have a promising osteogenic characteristics that support its potential in tissue engineering to repair bone defects. OBJECTIVES: was to evaluate the efficacy of autogenous (BMSCs) by its transplantation into local defects using (β-TCP) as a carrier. MATERIALS AND METHODS: Ten male Mongrel dogs weighing 25 Kg were used in this study. Right and critical size bone defects (CSDs) were performed intraorally at the mandibular premolar area by the aid of trephine bur, of 6mm outer diameter and 5mm inner diameter. Right side bone defects (Experimental) were filled with mixture of (β-TCP) and (BMSCs) which was taken from bone marrow aspirate concentrates (BMACs) from the same animal. Meanwhile, the left side bone defects (control) were left empty for healing spontaneously. The effect of (BMSCs) was assessed histologically as well as histomorphometrically after 6 weeks. RESULTS Greater amount of bone formation was noticed in (CSDs) filled with (β-TCP) and (BMSCs). The amounts of new bone formed in the defects filled with (β-TCP) and (BMSCs) were significantly greater than those formed within the defects that were left empty. CONCLUSIONS: Autogenous (BMSCs) has excellent osteogenic characteristics and can be added to bone grafts following surgical and periodontal surgeries to enhance bone regenerative capacity.

INTRODUCTION: Biomimetic enamel reconstruction is a significant topic in material science and dentistry as a novel approach for the treatment of dental caries or erosion. Compared to other conventional treatments, biocompatible and biodegradable chitosan hydrogel, with its antimicrobial properties shows promise as a biomaterial for the prevention, restoration, and treatment of defective enamel. OBJECTIVES: The present study was designed to investigate the effect of chitosan on the remineralization of enamel. MATERIALS AND METHODS Sound human premolars extracted for orthodontic reasons and were sectioned into 1mm thick slices.30 slices were selected and randomly divided into 3 equal groups (10 slices per group) as follows: GroupI: Control group, the slices were etched with 37% phosphoric acid for 30 seconds. Group II: The slices were etched with 37% phosphoric acid for 30 seconds, coated with bonding agent and chitosan hydrogel. Then slices were incubated at 37oC in artificial saliva solution for 5 days. Group III: The slices were etched with 37% phosphoric acid for 30 seconds, coated with bonding agent and chitosan hydrogel. Then slices were incubated at 37oC in artificial saliva solution for 10 days. After remineralization, the enamel surfaces were ultrasonically cleaned for 2 minutes and analyzed with scanning electron microscope (SEM) in order to observe induced structural changes on the enamel surface then elemental analysis and Ca/P ratios were carried out using Energy Dispersive Analysis X-Ray (EDAX) spectrometer. The obtained data were statistically analyzed. RESULTS: Morphological changes on the enamel surface after application of chitosan observed by SEM revealed the regeneration of an enamel-like layer in both treated samples. There was a statistically significant difference between the Ca/P ratios of the treatment groups compared to that of the control group. CONCLUSIONS: The ultrastructural and elemental alterations noticed in this study substantiate the use of chitosan in cases of dental erosions

INTRODUCTION: The use of platelet concentrates remains controversial. Several techniques for platelet concentrates are available and eachmethod leads to a different product with different biology and potential uses. Platelet rich fibrin (PRF) is an autologous biomaterial composedof a fibrin clot matrix entrapping leukocytes, cytokines, living progenitor cells, and platelets capable of releasing various growth factors. Oneof the recent platelet concentrates is the mineralized plasmatic matrix (MPM) which has a different way of preparation. It creates a stablehomogeneous single-moldable compound.OBJECTIVES: The aim of this experimental study was to compare the effect of PRF to MPM when combined with biphasic calciumphosphate alloplast in treating horizontal critical sized ridge defects in a canine model.MATERIALS AND METHODS: A split mouth design was carried out using the third and fourth mandibular premolars of two healthymongrel dogs. A total of eight horizontal critical sized ridge defects were surgically created. The defects on the left side (group I); weremanaged with MPM composite, MPM compact layer, then collagen membrane. On the right side (group II); defects were managed with PRFmixed with biphasic calcium phosphate alloplast followed by the application of PRF compact strips, then collagen membrane. The dogs weresacrificed after 4 weeks. Samples were dissected and prepared for histological evaluation.RESULTS: Histological results showed that quality of bone formed in MPM group was superior to PRF. This was evident with the formationof well-organized compact bone in MPM specimens versus immature woven trabecular bone in PRF ones.CONCLUSIONS: The fibrin network that is produced in the MPM composite allows for its homogeneity. This offers a very good stability forthe graft which was found to be more effective in enhancing wound healing during guided bone regeneration of horizontal ridge defects.KEYWORDS: Platelet Rich Fibrin, Mineralized Plasmatic Matrix, Guided bone regeneration, Horizontal ridge defects, Biphasic calcium

Introduction:Neostigmine is parasympathomimetic drug. It is commonly used for treatment of myasthenia gravis, glaucoma, urinary retention, xerostomia, and post-operative ileus. Parasympathomimetic drugs increase the rate of salivation. Dry mouth is a frequent clinical complain among diabetic patients. Objectives:The present study is designed to investigate the effect of neostigmine administration on the ultrastructure of the parotid salivary gland in rats with induced diabetes. Materials and methods: Twenty one adult male rats were divided into three equal groups (seven rats each) Group I: Control group, Group II: Induced diabetes group (with no treatment), Group III: Induced diabetes group (with Therapeutic doses of Neostigmine which were administered intramuscularly every other day for one month. Diabetes was induced by a single intravenous injection of Streptozotocin. After one month all rats were sacrificed and the parotid glands were excised and processed for scanning electron microscopy. Histomorphometric analysis of the number of the intra-cellular vacuoles was done, and the data obtained were statistically analyzed. Results There was a statistically significant difference between the studied groups regarding the diameter of secretory granules, as it was increased in neostigmine treated group and decreased in diabetic group. Also there was restoration of the density and organization of the nerve distribution adjacent to secretory acini in neostigmine treated group. Conclusions: The ultrastructural findings noticed in this study substantiate the use of Neostigmine in cases of diabetes associated xerostomia.

INTRODUCTION: The Amnion Chorion Membrane (ACM) has favorable regenerative properties which facilitates its use for coveringimmediate dental implants.OBJECTIVES: To evaluate clinically and histologically the effect of Amnion Chorion membrane in augmenting immediately placed dentalimplants compared to connective tissue graft (CTG)MATERIALS AND METHODS: This study was conducted clinically on eighteen upper hopeless anterior/premolar teeth scheduled forextraction and immediate implant placement. Patients were divided into two groups: in the first group, nine immediate implants were coveredwith ACM, and in the second group nine immediate implants were covered with CTG. Keratinized mucosal width (KMW), keratinized mucosalthickness (KMT) and healing score were recorded for both groups at 7 , 14 , 30 and 90 daysRESULTS: The KMT showed an increase by 26% in the test group while in the control group it decreased by 6.5% by the end of the studyperiod. Regarding the healing scores both groups showed marked improvement throughout the study, lower values of healing scores were notedin the test group. Clinical results were confirmed by histological examination which revealed that oral mucosa of both groups showedparakeratinized gingival epithelium. The connective tissue of the test group showed more regularly arranged ,thick bundles.CONCLUSIONS Both treatment modalities were satisfactory but the ACM offered more positive results concerning the mucosal thicknessand healing scores.KEYWORDS: Immediate implants, ACM, Connective tissue graft, Soft tissue

Introduction: Orthodontic relapse is a physiological response of the supporting tissues to force application threatening the success of orthodontic therapy. The objective of this study was to evaluate the influence of local application of simvastatin on the magnitude of orthodontic relapse. Methods: Orthodontic tooth movement was induced in 10 white New Zealand rabbits. After 21 days of active tooth movement, orthodontic appliances were removed and the experimental teeth were allowed to relapse for further 21 days. During the relapse phase, one mandibular quadrant received local simvastatin administration while the corresponding mandibular quadrant received control vehicle solution on a weekly basis. Magnitudes of experimental tooth movement and post-orthodontic relapse were calculated. Results: The mean relapse magnitude was 1.31±0.53mm in the quadrant receiving control vehicle solution and 1.14±0.47mm in the quadrant receiving simvastatin administration. Neither the relapse magnitude nor the relapse percentage showed a significant difference between the two quadrants. Conclusion: Local simvastatin administration could not minimize post-orthodontic relapse magnitude to a significant level.

INTRODUCTION: studies concerning healing of extraction sockets revealed that sockets were filled with new bone by as much as two thirds in 40 days and completely filled with new bone in 10 weeks. There have been many studies demonstrating the bone-promoting effect of simvastatin local application in animal models. Simvastatin was shown to increase bone volume, bone formation rate, and bone compressive strength. The use of statins for bone regeneration is a promising and growing area of research. OBJECTIVES: The aim of this study was to compare between the amounts of resorption that occurs in the healing extraction socket left to heal spontaneously to the amount of resorption that occurs in the healing extraction socket filled with simvastatin gel. MATERIALS AND METHODS: Right and left first molars were extracted from 20 rats’ mandibles’. Right side extraction sockets (Experimental) were filled with 2.5% simvastatin gel, while the left side sockets (Controls) were allowed to heal spontaneously. The rats were humanely sacrificed at 1st,2nd,3rd and 4th week postoperatively, and the specimens’ height and width were measured using a bone caliper. RESULTS: The mid-buccal height as well as the buccolingual width of the alveolar bone on the simvastatin-treated side was relatively higher and thicker than the control side indicating that less resorption had occurred on that side. CONCLUSIONS: The present study provided evidence that a single topical application of 2.5% simvastatin gel improve the quality of the new bone of the healing extraction socket and decreases bone resorption.

Introduction Posttreatment relapse is a major challenging clinical issue. The objective of this study was to evaluate the effect of local administration of simvastatin on posttreatment relapse. Methods Orthodontic tooth movement was induced in 10 white New Zealand rabbits. After 21 days of active tooth movement, the orthodontic appliances were removed, and the experimental teeth were allowed to relapse for 21 days. During the relapse phase, 1 mandibular quadrant received local simvastatin administration, and the other received the control vehicle solution on a weekly basis. Three-dimensional models of the experimental teeth were created to allow the measurement of experimental tooth movement and posttreatment relapse. The animals were killed at the end of the relapse phase for histomorphometric analysis of alveolar bone remodeling. Results The mean relapse percentages were 75.83% in the quadrant receiving the control vehicle solution and 62.01% in the quadrant receiving simvastatin. Neither the relapse magnitude nor the relapse percentage showed a significant difference between the 2 quadrants. Histomorphometric analyses showed that local simvastatin administration yielded a significant reduction in the area of active bone-resorptive lacunae and a significant increase in newly formed bone area. Conclusions Although local administration of simvastatin aids in bone remodeling associated with posttreatment relapse by reducing the area of active bone resorption and upregulating bone formation, it did not significantly minimize posttreatment relapse.