Edmund Khoo

Cytokine Expression and Accelerated Tooth Movement

It has been shown that inhibiting the expression of certain cytokines decreases the rate of tooth movement. Here, we hypothesized that stimulating the expression of inflammatory cytokines, through small perforations of cortical bone, increases the rate of bone remodeling and tooth movement. Forty-eight rats were divided into 4 groups: 50-cN force applied to the maxillary first molar (O), force application plus soft tissue flap (OF), force application plus flap plus 3 small perforations of the cortical plate (OFP), and a control group (C). From the 92 cytokines studied, the expression of 37 cytokines increased significantly in all experimental groups, with 21 cytokines showing the highest levels in the OFP group. After 28 days, micro-computed tomography, light and fluorescent microscopy, and immunohistochemistry demonstrated higher numbers of osteoclasts and bone remodeling activity in the OFP group, accompanied by generalized osteoporosity and increased rate of tooth movement.

Effect of micro-osteoperforations on the rate of tooth movement

INTRODUCTION Our objectives were to study the effect of micro-osteoperforations on the rate of tooth movement and the expression of inflammatory markers. METHODS Twenty adults with Class II Division 1 malocclusion were divided into control and experimental groups. The control group did not receive micro-osteoperforations, and the experimental group received micro-osteoperforations on 1 side of the maxilla. Both maxillary canines were retracted, and movement was measured after 28 days. The activity of inflammatory markers was measured in gingival crevicular fluid using an antibody-based protein assay. Pain and discomfort were monitored with a numeric rating scale. RESULTS Micro-osteoperforations significantly increased the rate of tooth movement by 2.3-fold; this was accompanied by a significant increase in the levels of inflammatory markers. The patients did not report significant pain or discomfort during or after the procedure, or any other complications. CONCLUSIONS Micro-osteoperforation is an effective, comfortable, and safe procedure to accelerate tooth movement and significantly reduce the duration of orthodontic treatment.

Osteogenic Effect of High-frequency Acceleration on Alveolar Bone

Mechanical stimulation contributes to the health of alveolar bone, but no therapy using the osteogenic effects of these stimuli to increase alveolar bone formation has been developed. We propose that the application of high-frequency acceleration to teeth in the absence of significant loading is osteogenic. Sprague-Dawley rats were divided among control, sham, and experimental groups. The experimental group underwent localized accelerations at different frequencies for 5 min/day on the occlusal surface of the maxillary right first molar at a very low magnitude of loading (4 µε). Sham rats received a similar load in the absence of acceleration or frequency. The alveolar bone of the maxilla was evaluated by microcomputed tomography (µCT), histology, fluorescence microscopy, scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR imaging), and RT-PCR for osteogenic genes. Results demonstrate that application of high-frequency acceleration significantly increased alveolar bone formation. These effects were not restricted to the area of application, and loading could be replaced by frequency and acceleration. These studies propose a simple mechanical therapy that may play a significant role in alveolar bone formation and maintenance.

Saturation of the Biological Response to Orthodontic Forces and Its Effect on the Rate of Tooth Movement

OBJECTIVES Investigate the expression and activity of inflammatory markers in response to different magnitudes of orthodontic forces and correlate this response with other molecular and cellular events during orthodontic tooth movement. SETTING AND SAMPLE POPULATION CTOR Laboratory; 245 Sprague Dawley male rats. METHODS AND MATERIALS Control, sham, and 5 different experimental groups received different magnitudes of force on the right maxillary first molar using a coil spring. In the sham group, the spring was not activated. Control group did not receive any appliance. At days 1, 3, 7, 14, and 28, the maxillae were collected for RNA and protein analysis, immunohistochemistry, and micro-CT. RESULTS There was a linear relation between the force and the level of cytokine expression at lower magnitudes of force. Higher magnitudes of force did not increase the expression of cytokines. Activity of CCL2, CCL5, IL-1, TNF-α, RANKL, and number of osteoclasts reached a saturation point in response to higher magnitudes of force, with unchanged rate of tooth movement. CONCLUSION After a certain magnitude of force, there is a saturation in the biological response, and higher forces do not increase inflammatory markers, osteoclasts, nor the amount of tooth movement. Therefore, higher forces to accelerate the rate of tooth movement are not justified.

Throwing the baby out with the bath water

This article considers proposed changes to the social services complaints procedure. The Health and Social Care (Community Health and Standards) Act 2003 makes provision for complaints Panels to be taken away from local authorities. The suggestion is that in future the Commission for Social Care Inspection (CSCI) should be responsible for running all Panels. We argue that this proposal is not grounded in a satisfactory rationale, is not the best solution to any concerns about Panels and could lead to problems for all concerned: complainants, Panel members, complaints officers and the CSCI itself.

Age-dependent biologic response to orthodontic forces

Introduction: Orthodontic tooth movement results from increased inflammation and osteoclast activation. Since patients of all ages now routinely seek orthodontics treatment, we investigated whether age‐dependent biologic responses to orthodontic force correlate with the rate of tooth movement. Methods: We studied 18 healthy subjects, adolescents (11‐14 years) and adults (21‐45 years), with Class II Division 1 malocclusion requiring 4 first premolar extractions. Canines were retracted with a constant force of 50 cN. Gingival crevicular fluid was collected before orthodontic treatment and at days 1, 7, 14, and 28 after the canine retraction. Cytokine (IL‐1&bgr;, CCL2, TNF‐&agr;) and osteoclast markers (RANKL and MMP‐9) were measured using antibody‐based protein assays. Pain and discomfort were monitored with a numeric rating scale. The canine retraction rate was measured from study models taken at days 28 and 56. Results: Although the cytokine and osteoclast markers increased significantly in both age groups at days 1, 7, and 14, the increases were greater in adults than in adolescents. Interestingly, the rate of tooth movement in adults was significantly slower than in adolescents over the 56‐day study period. Adults also reported significantly more discomfort and pain. Conclusions: Age is a significant variable contributing to the biologic response to orthodontic tooth movement. Adults exhibited a significantly higher level of cytokine and osteoclasts activity but, counterintuitively, had a significantly slower rate of tooth movement. HighlightsAge is an important factor in the biologic response to orthodontic forces.Cytokine and osteoclast markers increased significantly in adolescents and adults in the first weeks of orthodontic force application.Increases in cytokine and osteoclast markers are greater in adults than in adolescents in response to the same orthodontic force level.The rate of tooth movement in adults is slower than in adolescents.Adults report more pain and discomfort than adolescents in response to same force level.

Different Methods of Accelerating Tooth Movement

The increased demand for fast orthodontic treatment, especially by adult patients, has lead researchers in the field to focus on accelerated tooth movement with the aim of reducing treatment duration while maintaining treatment efficiency. The approach that researchers select to accelerate the rate of movement depends on their interpretation of the data on the biology of tooth movement. A researcher who chooses to amplify body reactions to orthodontic forces may either try to increase the release of cytokines (if they believe inflammatory responses of the PDL and bone are the key factor in controlling the rate of tooth movement) or optimize the mechanical stimulation (if they believe orthodontic tooth movement is a direct physiologic response to mechanical stimulation). Other researchers may choose not to mimic the body’s response to orthodontic forces but instead to artificially increasing the number of osteoclasts. These approaches include local or systemic induction of different chemical factors or application of physical stimuli that can increase the number of osteoclasts independent of orthodontic forces. It should be emphasized that, in spite of some disagreement about the initial trigger that start the cascade of events leading to bone resorption and tooth movement, all theories agree that osteoclast activation is the main rate-controlling factor in orthodontic tooth movement.