Chinapa Sangsuwon

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.

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.

Vibration paradox in orthodontics: Anabolic and catabolic effects

Vibration in the form of High Frequency Acceleration (HFA) is anabolic on the craniofacial skeleton in the absence of inflammation. Orthodontic forces trigger an inflammation-dependent catabolic cascade that is crucial for tooth movement. It is unknown what effect HFA has on alveolar bone if applied during orthodontic treatment. The objectives of this study are to examine the effect of HFA on the rate of tooth movement and alveolar bone, and determine the mechanism by which HFA affects tooth movement. Adult Sprague Dawley rats were divided to control, orthodontic force alone (OTM), and different experimental groups that received the same orthodontic forces and different HFA regimens. Orthodontic tooth movement was assessed when HFA parameters, frequency, acceleration, duration of exposure, and direct or indirect application were varied. We found that HFA treatment significantly enhanced the inflammation-dependent catabolic cascade during orthodontic tooth movement. HFA treatment increased inflammatory mediators and osteoclastogenesis, and decreased alveolar bone density during orthodontic tooth movement. Each of the HFA variables produced significant changes in the rate of tooth movement and the effect was PDL-dependent. This is the first report that HFA enhances inflammation-dependent catabolic cascades in bone. The clinical implications of our study are highly significant, as HFA can be utilized to enhance the rate of orthodontic tooth movement during the catabolic phase of treatment and subsequently be utilized to enhance retention during the anabolic remodeling phase after orthodontic forces are removed.

High-Frequency Acceleration Therapeutic Tool to Preserve Bone following Tooth Extractions

A common problem in clinical dentistry is the significant and rapid bone loss that occurs after tooth extraction. Currently there is no solution for the long-term preservation of alveolar bone. Previously, we showed that high-frequency acceleration (HFA) has an osteogenic effect on healthy alveolar bone. However, it is not known if HFA can preserve alveolar bone after extraction without negatively affecting wound healing. The purpose of this study was to evaluate the effect of HFA on alveolar bone loss and the rate of bone formation after tooth extraction. Eighty-five adult Sprague-Dawley rats were divided into 3 groups: control, static (static load), and HFA. In all groups, the maxillary right third molar was extracted. The HFA group received HFA for 5 min/d, applied through the second molar. The static group received the same magnitude of static load. The control group did not receive any stimulation. Some animals received fluorescent dyes at 26 and 54 d. Samples were collected on days 0, 7, 14, 28, and 56 for fluorescence microscopy, micro–computed tomography, histology, RNA, and protein analyses. We found that HFA increased bone volume in the extraction site and surrounding alveolar bone by 44% when compared with static, while fully preserving alveolar bone height and width long-term. These effects were accompanied by increased expression of osteogenic markers and intramembranous bone formation and by decreased expression of osteoclastic markers and bone resorption activity, as well as decreased expression of many inflammatory markers. HFA is a noninvasive safe treatment that can be used to prevent alveolar bone loss and/or accelerate bone healing after tooth extraction.

Biphasic Theory and the Biology of Tooth Movement

Teeth move through alveolar bone through naturally occurring drift or in response to orthodontic forces. Orthodontists want to optimize this movement while reducing potential risk factors. Orthodontic researchers have taken on this clinical challenge by uncovering the biological phenomena associated with tooth movement. It was believed that teeth move due to compression and tension of the alveolar bone induced by orthodontic forces that cause bone resorption and formation respectively. However, research on bone biology has shown that bone does not respond to static forces, and in fact, bone is not the target of our orthodontic forces. In this chapter, we show how orthodontic forces stimulate an inflammatory response in periodontal ligaments (PDL) that in turn activates the bone remodeling machinery.

Anabolic Effects of MOPs: Cortical Drifting

Micro-osteoperforations (MOPs) are well known for their catabolic effect that is characterized by the release of inflammatory markers in response to minor trauma to the bone, which in turn activate osteoclasts and stimulate bone resorption. This effect has led to many useful applications in orthodontics such as accelerating tooth movement. However, osteoclasts will be replaced by osteoblasts to initiate a repair phase that restores the structure of resorbed bone. This phase is known as the anabolic phase. The significance of the anabolic effect on the alveolar bone lays in it many applications during orthodontic treatment such as cortical drifting, tooth movement through maxillary sinuses that expanded the boundaries of orthodontic treatment.

Step-by-Step Guide for Performing Micro-osteoperforations

In this chapter we will review the clinical protocol for applying micro-osteoperforations (MOPs) in daily clinical practice. This is a clinical guide for step-by-step delivery of MOPs based on clinician judgment. Additionally, the tools that have been developed to facilitate MOP delivery are introduced.

Biphasic Theory of Tooth Movement: Cytokine Expression and Rate of Tooth Movement

Understanding the molecular and cellular events during orthodontic tooth movement can greatly impact daily orthodontic practice. Selecting the most appropriate force magnitude, knowing precise tooth movement, optimizing activation intervals, preventing side effects, and, most importantly, developing techniques that increase the rate of tooth movement are all influenced by this understanding. These events can be divided into two main phases, a catabolic phase, where osteoclast-driven bone resorption determines the rate of tooth movement, and an anabolic phase, where osteoblast-driven bone formation reestablishes and maintains alveolar bone integrity of the new occlusion. These two phases are not simultaneous or independent – the catabolic phase is required and always precedes the anabolic phase. We call this biological phenomenon the Biphasic Theory of Tooth Movement. While cytokines play an important role in initiating the catabolic phase, interaction between osteoclasts and osteoblasts regulates the anabolic phase. Therefore, to increase the rate of tooth movement, acceleration techniques must focus first on producing higher cytokine activity and second on enhancing osteoclast and osteoblast interactions to expand the boundary of tooth movement and maintain the integrity of alveolar bone in the newly established occlusion. In this chapter, we will review the events of both catabolic and anabolic phases of treatment and how to manipulate them to enhance orthodontic outcomes.

Osteoclasts: The Biological Knife In Sutural Responses To Mechanical Stimulation

Background: It is assumed that transverse force physically opens maxillary sutures and induces a tensile stress that directly stimulates bone formation. However, orthopedic/ orthodontic tensile stresses are static, which cannot directly stimulate bone formation. We hypothesize that the anabolic response to transverse force is indirect, resulting from inflammation-induced osteoclast activation followed by a transition into osteogenesis. The purpose of this study was to evaluate the tissue, cellular and molecular responses in the sutures during maxillary expansion. Materials & Methods: Adult Sprague-Dawley rats where divided into 4 groups: untreated Control (C), Sham (S), Experimental (Exp), and Experimental with nonsteroidal anti-inflammatory medication (Exp+NSAID). Maxillae were collected 0, 1, 3, 7, 14, and 28 days post-expansion for micro-computed tomography, fluorescence and light microscopy, gene and protein expression, and immunohistochemistry analysis. Results: The Exp group showed early expression of inflammatory cytokines in the mid-palatal suture that was followed by osteoclast activation, bone resorption and a transient decrease in bone density. A significant widening of the suture occurred only after osteoclast activation and bone resorption. Bone formation was delayed, occurring after the initial catabolic phase. NSAIDs significantly decreased the magnitude of maxillary sutural widening and bone formation in response to transverse forces. During the transition from the catabolic to the anabolic response, expression of communicator molecules between osteoclasts and osteoblasts increased significantly. Conclusion: We demonstrated that maxillary transverse force stimulated three distinct phases in the mid-palatal suture: 1) the Catabolic Phase starts with inflammatory markers and osteoclast recruitment and activity, 2) the Transition Phase, where osteoclasts activate osteoblast activity, 3) the Anabolic Phase, during which osteoblasts restore the integrity of the skeleton. INNOVATION: Our findings are novel and support a new theory for sutural response to orthopedic forces that emphasizes the importance of osteoclasts in the process and makes these cells the possible target of orthopedic treatment: 1) as the ”biological knife” at the sutures that allows the separation of maxillae for orthopedic movement, and 2) as the trigger for osteoblasts activation and bone regeneration, anytime we need to stimulate bone formation especially at the surface of the cortical bone. Mani Alikhania,b,c, Sarah Alansaria,b, Mohammed M Al Jearahd, Niraj Gadhavia, Mohammad A Hamidaddina, Fadwa A Shembeshd, Chinapa Sangsuwona,d, Jeanne M Nervinaa,d, Cristina C Teixeiraa,d a Consortium for Translational Orthodontic Research, Hoboken, NJ b Forsyth Institute, Cambridge, MA c Department of Developmental Biology, Harvard School of Dental Medicine, Boston, MA d Department of Orthodontics, New York University College of Dentistry, New York, NY Corresponding Author: Cristina Teixeira, cristina.teixeira@nyu.edu Citation: Alikhani M, Alansari S, Al Jearah MM, Gadhavi N, Hamidaddin MA, Shembesh FA, Sangsuwon C, Nervina JM, Teixeira CC. Innovation. April 2018. 1(4):e1. doi:10.30771/2018.3 Submitted April 8, 2018 Accepted April 9, 2018

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.