limited capacity for movement without further modifications - rendering it obsolete in modern orthodontic practice. begg's appliance returning to australia in the 1920s, the renowned orthodontist, raymond begg, applied his knowledge of ribbon arch appliances, which he had learnt from the angle school. on top of this, begg recognised that extracting teeth was sometimes vital for successful outcomes and sought to modify the ribbon arch appliance to provide more control when dealing with root positioning. in the late 1930s, begg developed his adaptation of the appliance which took three forms. firstly, a high-strength 16-mil round stainless steel wire replaced the original precious metal ribbon arch. secondly, he kept the same ribbon arch bracket but inverted it so that it pointed toward the gums instead of away from them. lastly, auxiliary springs were added to control root movement. this resulted in what would come to be known as the begg appliance (fig 10.19).5 with this design friction was decreased since contact between wire and bracket was minimal, and binding minimized due to tipping and uprighting being used for anchorage control (see fig 8.26), which lessened contact angles between wires and corners of bracket tip edge system dr. begg's influence is still seen in modern appliances, such as tip-edge brackets. this type of bracket incorporates a rectangular slot cutaway on one side to allow for crown tipping with no incisal deflection of an archwire; allowing teeth to be tipped during space closure and then uprighted through auxiliary springs or even a rectangular wire for torque purposes in finishing. at initial stages of treatment, small-diameter steel archwires should be used when working with tip-edge brackets. contemporary edgewise systems throughout time, there has been a shift in which appliance is favored by dentists. in particular, during 1960s, when it was introduced, begg appliance gained wide popularity due to its efficiency compared to edgewise appliance of that era; it could produce same results with less investment from dentist's part. nevertheless, since then there have been advances in technology and sophistication of edgewise appliances which led to an opposite conclusion: nowadays, edgewise is more efficient than begg appliance thus explaining why it is commonly used. automatic rotational control at the beginning, angle attached eyelets to the edges of archwires so that they could be held with ligatures and help manage rotations. now, however, no extra ligature is needed due to either twin brackets or single brackets that have added wings touching underneath the wire (lewis or lang brackets). both types of brackets simplify obtaining moments that control movements along a particular plane of space. alteration in bracket slot dimensions in modern dentistry, two types of edgewise appliance exist: the 18- and 22-slot varieties. while these appliances are used differently, the introduction of a 20-slot device with more precise features has been considered but not pursued yet. straight-wire bracket prescriptions rather than rely on the same bracket for all teeth, l.f. andrews found a way to make different brackets for each tooth in the 1980s, thanks to the increased convenience of bonding. this adjustment enabled him to avoid having multiple bends in archwires that would have been needed to make up for variations in tooth anatomy. ultimately, this led to what was termed as "straight-wire appliance" system - an edgewise appliance which greatly enhanced its efficiency.the modern edgewise appliance has slightly different construction than the original one. instead of relying on faciolingual bends to accommodate variations among teeth, each bracket has a correspondingly varying base thickness depending on the tooth it is intended for. however, due to individual differences between teeth, this does not completely eliminate the need for compensating bends. accurately placing the roots of many teeth requires angling brackets in relation to the long axis of the tooth. traditionally, this mesiodistal root positioning necessitated using second-order, or tip, bends along the archwire. however, angling the bracket or bracket slot eliminates this need for bends. given the discrepancies in inclination of facial surfaces across individual teeth, placing a twist, otherwise known as third-order or torque bends, into segments of each rectangular archwire was initially required with the edgewise appliance. these bends were necessary for all patients and wires, not just to avoid any unintentional movement of suitably placed teeth or when moving roots facially or lingually. angulation of either brackets or slots can minimize the need for second-order or tip bends on archwires. contemporary edgewise appliances come with brackets designed to adjust for any facial inclinations, thereby eliminating or reducing any third-order bends. these brackets already have angulation and torque values built in so that each rectangluar archwire can be contorted to form a custom fit without inadvertently shifting any correctly positioned teeth. without bracket angulation and torque, second-order or tip bends would still be required on each patient's archwire. methods upper and lower jaw functional expanders a typical treatment for incorrectly positioned teeth (malocclusion) takes from one to two years, with braces being adjusted every four to 10 weeks by orthodontists, while university-trained dental specialists versed in the prevention, diagnosis and treatment of dental and facial irregularities. orthodontists offer a wide range of treatment options to straighten crooked teeth, fix irregular bites, and align the jaws correctly. there are many ways to adjust malocclusion. in growing patients there are more options to treat skeletal discrepancies, either by promoting or restricting growth using functional appliances, orthodontic headgear or a reverse pull facemask. most orthodontic work begins in the early permanent dentition stage before skeletal growth is completed. if skeletal growth has completed, jaw surgery is an option. sometimes teeth are extracted to aid the orthodontic treatment (teeth are extracted in about half of all the cases, most commonly the premolars). orthodontic therapy may include using fixed or removable appliances. most orthodontic therapy is delivered using appliances that are fixed in place, for example, with braces that are adhesively bonded to the teeth. fixed appliances may provide greater mechanical control of the teeth; optimal treatment outcome is improved by using fixed appliances. fixed appliances may be used, for example, to rotate teeth if that do not fit the arch shape of the other teeth in the mouth, to adjust multiple teeth to different places, to change tooth angle of teeth, or to change the position of a tooth's root. this treatment course is not preferred where a patient has poor oral hygiene, (as decalcification, tooth decay or other complications may result. if a patient is unmotivated (insofar as treatment takes several months and requires commitment to oral hygiene), or if malocclusions are mild. biology of tooth movement and how advances in gene therapy and molecular biology technology may shape the future of orthodontic treatment. braces dental braces. braces are usually placed on the front side of the teeth, but they may also be placed on the side facing the tongue (called lingual braces). brackets made out of stainless steel or porcelain are bonded to the center of the teeth using an adhesive. wires are placed in a slot in the brackets which allows for controlled movement in all three dimensions. apart from wires, forces can be applied using elastic bands, and springs may be used to push teeth apart or to close a gap. several teeth may be tied together with ligatures and different kinds of hooks can be placed to allow for connecting an elastic band. clear aligners are an alternative to braces, but insufficient evidence exists to determine their effectiveness. treatment duration the time required for braces varies from person to person as it depends on the severity of the problem, the amount of room available, the distance the teeth must travel, the health of the teeth, gums, and supporting bone, and how closely the patient follows instructions. on average, however, once the braces are put on, they usually remain in place for one to three years. after braces are removed, most patients will need to wear a retainer all the time for the first six months, then only during sleep for many years. headgear orthodontic headgear—sometimes referred to as an "extra-oral appliance"—is a treatment approach that requires the patient to have a device strapped onto their head to help correct malocclusion—typically used when the teeth do not align properly. headgear is most often used along with braces or other orthodontic appliances. while braces correct the position of teeth, orthodontic headgear—which as the name suggests is worn on or is strapped onto the patient's head—is most often added to orthodontic treatment to help alter the alignment of the jaw, although there are some situations in which such an appliance can help move teeth, particularly molars. full orthodontic headgear with headcap, fitting straps, facebow and elastics whatever the purpose, orthodontic headgear works by exerting tension on the braces via hooks, a facebow, coils, elastic bands, metal orthodontic bands, and other attachable appliances directly into the patient's mouth. it is most effective for children and teenagers because their jaws are still developing and can be easily manipulated. (if an adult is fitted with headgear, it is usually to help correct the position of teeth that have shifted after other teeth have been extracted.) thus, headgear is typically used to treat a number of jaw alignment or bite problems such as overbite and underbite. palatal expansion palatal expansion can be best achieved using a fixed tissue born appliance. removable appliances can push teeth outwards but is less effective at maxillary sutural expansion. the effects of a removable expander may look the same as they push teeth outwards but should not be confused with actually expanding the palate. proper palate expansion can create more space for teeth as well as improve both oral and nasal airflow. jaw surgery jaw surgery may be required to fix severe malocclusions. the bone is broken during surgery and is stabilized with titanium (or bioresorbable) plates and screws to allow for healing to take place. after surgery, regular orthodontic treatment is used to move the teeth into their final position. during treatment to reduce pain during the orthodontic treatment, low-level laser therapy (lllt), vibratory devices, chewing adjuncts, brainwave music, or cognitive behavioral therapy can be used. however, the supporting evidence is of low quality, and the results are inconclusive. post treatment after orthodontic treatment has completed, there is a tendency for teeth to return, or relapse, back to their pre-treatment positions. over 50% of patients have some reversion to pre-treatment positions within 10 years following treatment. to prevent relapse, the majority of patients will be offered a retainer once treatment has completed and will benefit from wearing their retainers. retainers can be either fixed or removable. removable retainers removable retainers are made from a clear plastic, and they are custom-fitted for the patient's mouth. it has a tight fit and holds all of the teeth in position. there are many types of brands for clear retainers including zendura retainer, essix retainer, and vivera retainer. hawley retainer is also a removable orthodontic appliance made from a combination of plastic and metal that is molded custom to fit the patient's mouth. removable retainers will be worn for different periods of time depending on patient need to stabilise the dentition. fixed retainers fixed retainers are a simple wire fixed to the tongue-facing part of the incisors using dental adhesive and can be specifically useful to prevent rotation in incisors. other types of fixed retainers can include labial or lingual braces, with brackets fixed to the teeth. palatal expander orthodontic headgear an x-ray taken for skull analysis top (left) and bottom retainers clear aligners (invisalign) invisalign is another form of orthodontics that is commonly used today. many patients do not like the appearance of traditional metal braces, so they opt for clear removable aligners. there was a lot of controversy about the effectiveness of invisalign, but with years of advancements, invisalign's results can now be closely compared to traditional braces but with a lot more freedom and faster results. process after booking an appointment with a dentist, the patient sets up a consultation. during the consultation the dentist or the dental assistant will scan the individual's teeth with a machine called itero. the itero machine digitally scans the structure of the teeth and gums. the dentist is able to see a 3d model of the patient's teeth on the screen. unlike traditional braces, with invisalign one