Although TADs have been a relatively recent addition to the orthodontist's arsenal, there is actually a long history behind them. In the bibliography there are numerous references to doctors who used some sort of implant to move teeth many years before the introduction of TADs. Roberts was probably one of the first researchers to realize the potential of titanium implants as an orthodontic anchor and to conduct systematic research on the topic. His “first generation” TADS involved a regular dental implant in the retromolar area that was used to prolong second molars and close the space of frequently extracted first molars. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay However, it was Kanomi who established the term mini-implant and created the TAD the way we use it today [4]. Nowadays there are hundreds of different types of this appliance and a new field of orthodontic research. Anchor Value Newton's Third Law states that “for every action there is an equal and opposite reaction”. When attempting to move teeth orthodontists must recognize this law and realize that every time you attempt to move teeth there is the possibility of simultaneously creating unwanted tooth movement. Orthodontic anchorage has been defined since 1923 as “the base against which orthodontic force or the reaction of orthodontic force is applied” and essentially means the resistance to unwanted movement of the teeth. Any structure covered by the periodontal ligament (PDL) will move more or less under the application of force since the PDL is actually the apparatus that makes orthodontic movement possible. The philosophy behind using TADS as a skeletal anchor is that because they have no PDL, reactive forces will be absorbed by the bony structures and only desired therapeutic movements will be permitted. There are many different ways to get anchored. A simple classification could be as follows: Anchorage with the use of extraoral support (headgear or face mask, etc.) Anchorage with the use of intraoral appliances (Nance, lingual bow, etc.). Intermaxillary anchorage using the support of the teeth in the oral cavity. opposite dental arch (class II or III elastics) Anchorage by modification of fixed appliances (tip-back or eardrum flexions, buccal root torque, etc.). Skeletal anchorage (ankylotic teeth and all forms of implants or plates). It is a well-known fact that absolute anchorage or stabilization of teeth can only be reliably achieved by using ankylosed teeth or some type of implant or plate. Every other type of anchoring creates some sort of mutual force that must be manipulated or relies on the patient's compliance having a certain. degree of unpredictability [6]. Biology One of the major advantages of TADS is the versatility of placement. TADS can be placed in close proximity to the anchor point within the alveolar process, typically in an interradicular location. In this way the need for complex biomechanics is minimized while anchoring remains maximum. Over the past 20 years, numerous case reports and articles have been published highlighting the clinical application and potential of TADS [7]. However, both clinicians and researchers very often assume that TADS works identically to endosseous dental implants. It has been proven that regular endosseous dental implants are rigid after a certain period of time and capable of withstanding high orthodontic forces and prolonged loads. On the other hand, TAD research has shownthat larger forces (e.g., 10 N) cannot be routinely supported for an extended period (1-2 years) and mini implants are generally used for the movement of a few teeth over a period of 6-8 years. months. Persistently high failure rates appear to be a major problem of TADS. The most significant difference between regular dental implants and many of these TADs is the lack of osseointegration of mini implants. While it was desiredSince miniscrews do not fully osseointegrate and may be removed at the end of their use, the high failure rate (10-30%) and displacement may make such use difficult. For this reason, orthodontists have explored other skeletal anchoring options such as miniplates [12] and other extra-alveolar sites such as the palate for more favorable positioning of TADs. Osseointegration Generally the definition and mechanism of successful device implantation has been described with the term osseointegration. Osseointegration is the presence of vital load-bearing bone directly in contact with the implant. Most implant studies examine bone sections and quantify histological parameters at the bone-implant interface. Some of the variables that can be measured are the percentage of bone-to-implant contact (%BIC), the percentage of bone volume fraction (%BV/TV) within the threads of an implant, and bone remodeling (% bone formation rate /year, %BFR/year). However, the definition of “successful implantation” on a histological section is not easy and not easily measurable. Primary and secondary stability cannot be assessed on histological section and the same happens for almost all mechanical factors. The exact opposite occurs with a failed or failed implant. The presence of fibrous tissue and woven bone at the implant interface on histological sections indicates overload and predicts future failure. In general, there are many challenges in conducting endosseous implant research. The selection of an appropriate animal model, the interpretation and extrapolation of the results to humans, the ability to mimic the clinic by conducting long-term studies (>9-12 months), and the analysis of cellular and molecular responses in vitro for the clinical situation are just some of the problems that need to be solved. Histological variables Many studies have been published on different animal models, however there are limitations and advantages for each animal model and direct extrapolation of results to humans should be avoided. Some of the most important histomorphometric variables that provide information about mini implants are as follows: Bone implant contact (BIC) is measured in most histological studies. Although bone contact measured in studies is a static measurement, it actually describes a dynamic process. There is bone remodeling at the implant interface which makes the measurement dynamic. This means that different areas of the implant may contact the bone at different times as the bone increases or decreases due to remodeling. The rate of remodeling between species has been shown to be high in the vicinity of the implant and high at the implant interface, making it almost certain that bone contact will change. The literature indicates that the shape of the implant and the design of the implant threads can impact the amount of contact with the bone. Although measuring bone contact is important, it is not a direct predictor of implant success. A volume (BV) adjacent to the implant and contained within the threads. This specific bone is generated by contact osteogenesis or distant osteogenesis[20]. The biological basis in this case is that growthbone occurs towards an osteogenic surface, in areas where bone did not previously exist. Bone remodeling. The presence of vital bone at the implant interface is the key to success. One method for measuring metabolic activity at the implant interface is to estimate bone remodeling in the supporting cortical and trabecular compartments. Measurement of bone remodeling involves the use of intravital bone label. The rate of cortical and trabecular bone turnover in humans is estimated to be 2–10%/year and 25–30%/year, respectively. After implant placement, extensive bone remodeling occurs during the initial stages of healing which is usually described with the term regional accelerator phenomena (RAP) [22] Evaluate the histomorphometric variables of bone remodeling such as the rate of mineral apposition, mineralizing surface/bone surface (MS/BS) or bone formation rate (BFR) is measured in mineralized sections. These variables reveal the dynamic nature of metabolic activity in bone and certainly reveal more information than static variables such as BIC. It's interesting. Analysis of samples from various animal species demonstrated that, even after considering the time periods required for typical bone healing, a persistently high remodeling rate is observed in the bone adjacent to the implant over the long term (2 years after implantation). It is unclear, however, whether this is important for the long-term success of the implants. Microcomputed Tomography Microcomputed tomography (μCT) is the latest innovation in the study of bone healing and adaptation. μCT images provide 3D reconstructions of the region of interest and help overcome one of the major limitations of standard histology. This means that only a select number of 2D sections can be examined and the true 3D nature of the implant interface cannot be visualized. It seems that μCT will revolutionize static histological measurements but cannot currently replace dynamic histomorphometry. This new technology also presents some new types of problems to overcome, such as beam dispersion and hardening. Compared to traditional histology, μCT can collect the same information only in static measurements. Materials for TADS Titanium is an ideal biocompatible material that allows direct bone contact (osseointegration) between endosseous dental implants and the host bone. Miniscrew implants are generally made of titanium alloys. In contrast to dental implants, a high degree of osseointegration is not a requirement for mini orthodontic implants to function as anchoring devices. Stainless steel bone screws have also been widely used in orthognathic surgery for fracture fixation. Unlike titanium alloy, stainless steel screws tend to develop a fibrous tissue interface between the screw and the bone. This fact allows for easier recovery as it reduces the removal torque. Stainless steel TADs have been used for mass space closure showing promising results. There are two main issues regarding the primary stability of steel anchor devices and bone healing responses. Primary stability is defined as mechanical retention upon insertion and is quantified by insertion torque. It has been reported that a wide range of insertion torque values can achieve high TAD success rates. On the contrary, excessive insertion torque could cause negative effects such as bone necrosis and increased microdamage. When microdamages accumulate, they can contribute to MSI failure. The reason is that the mechanical properties,.
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