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So do you know how to bracket? A Basic Teaching Module Dr Jean Marc Retrouvey Ms FUNG, Karen Ms HRIT, Manuela McGill University, Faculty of Dentistry
Introduction • Precise bracket placement is the most important aspect in orthodontic alignment, after correct diagnosis and treatment planning procedures. • This factor is most crucial given the advent of pre­adjusted brackets and straight wire appliances. • The duration of treatment is shorter in cases where bracket placement is optimal. Poor bracketing will lead to extra time spent finishing proper alignment and occlusion, and possibly treating iatrogenic complications.
Rationale • Although intuitively simple, the difficulty of bracketing procedures is often underestimated. • There is currently no published literature that is made specifically to instruct optimum bracketing techniques to dental practitionners
Objectives • The aim of this presentation is to illustrate step­by­step bracketing techniques for undergraduate dental students using multimedia in the form of text, video and photos.
General steps in bracket bonding
Prophylaxis • Pre­bonding prophylaxis procedure – Using oil­free pumice mixed with water: tooth surfaces where the brackets are to be bonded must be cleaned.
Isolation of teeth (Cheek retractors)
Enamel etching In this step and all subsequent steps, salivary control and maintenance of a dry, uncontaminated field is essential. The acid etch (35% H3PO4) is placed on each tooth surface for ~15 seconds, then suctioned with a high speed (HS) suction and rinsed abundantly with water spray for the same time. Air dry the tooth surfaces until they appear frosty white.
Acid Etching
Proceed by quadrants
Rinse each tooth for 15 seconds
Dry the field (Chalky white enamel)
Apply a light coat of resin
Sealing – A very thin layer of unfilled resin is placed on the tooth surface, and gently air­ dried. It must be light cured for 20 seconds on each tooth. Bonding – Using a Ladmore composite instrument, coat the bracket base evenly with unfilled resin without any voids. Place the bracket on the tooth surface and press firmly in order to minimize resin excess and bracket drift, and maximize bond strength. Remove excess material with a scaler. Light cure for 20 seconds from the mesial and 20 seconds from the distal. In general, the bonding material will take 24­ 72 hours to set completely. Therefore patients must be instructed to not eat hard foods during this period to avoid any debonding from occurring.
We use gel not liquid for etching
Bonding kit Cure resin for 10 seconds
Select the proper bracket
The coloured dot must be placed disto­gingivally
Twin straight wire brackets are used at McGill, and have a unique prescription suited for each tooth. They are designed to obey Andrew’s 6 Keys of Occlusion. Position the bracket as precisely as possible
Visualization of position When placing brackets it is important to view the teeth from the correct aspect. Do not view the incisors from the side, or from above or below. This may require for the patient to turn the head, and the dentist to constantly change seating position.
Use a mirror to verify if the bracket is centered on the crown
Excellent bracketing relies on proper visualization of the crown, its convexity, and its long axis. Use a mouth mirror to view the crowns from the incisal/occlusal view to establish good angulation and to ascertain correct mesio­distal positioning of the bracket.
Remove excess composite around bracket
Excess composite Remove excess composite around the bracket with a scaler or an explorer before light curing. If not, it will encourage plaque accumulation.
Use height gage properly
The bracket placement gauge is used differently in different areas of the mouth: In the incisor regions, the gauge is placed at 90° to the labial surface.
In the canine, premolar and molar regions, the gauge is placed parallel with the occlusal plane
Place another bracket (22)
Verify bracket positioning
Tip and Torque in the position of incisors
1. Position incisal edges or marginal ridges • Position all the teeth at their proper level on the occlusal plane • Bracketing position will dictate the amount of extrusion • Combination of extrusion­intrusion
Bracket height • If the incisal edges are not worn out, you may want to use a height gage to position the bracket properly If
2. Extrusion of a tooth to be restored • Biological width • Extrusion vs CCL or in combination • Supracrestal fiberotomy should be performed to enhance the root extrusion and minimize bone deposition at the crestal margin
Limited orthodontics
Common Errors in Bracketing
Vertical Errors in Bracket Positioning Placing a bracket too gingivally or incisally is one of the most common errors in bracket placement. This is more prevalent in teeth that have not fully erupted. A bracket placed too gingivally will cause tooth extrusion, while if it is too incisal, intrusion would occur.
Bracket placed too gingivally
Vertical Errors Tips: A) imagine where the centre of the crown would be if the tooth was fully erupted. B) View the tooth surface from a mesio­distal aspect during bracket placement, and not from above or below. C) Use gingival margins as a guide
Bracket placed too incisally
Vertical positioning Vertical accuracy can be greatly improved by the use of a height gauge and bracket positioning charts.
Angulation Errors These errors generally occur when the bracket is placed at an angle on the crown. This is a common error when crowns have been worn down. Trick: Visualize the long axis of the tooth and disregard the incisal edge as a reference point. When aligning the teeth the position of the gingival margin is given priority over the position of the incisal edge.
Horizontal Errors Placing brackets too mesially or distally is common on canines and premolars – teeth with convex surfaces, as opposed to the flat surfaces of the incisors.
Tip: Visualization should be made from at least two angles to prevent this error. – One should look directly from the facial surface, and should verify occlusally with a mirror to prevent horizontal errors.
Too much composite on the bracket base will modify the labio lingual position of the bracket. This will lead to misalignment of the incisal edges
Bonding Errors Bonding Errors FIRST, IDENTIFY THE ERROR IF A BRACKET DEBONDS, AND AVOID REPEATING IT REBONDING All resin on the affected tooth surface must be carefully removed with a carbide bur. In case a new bracket is not available, the base of the original bracket must be sandblasted. Once the tooth is cleaned, it is etched and sealed, and the bracket is rebounded back into place. The neighboring brackets are first re­ligated, and the rebounded bracket is subsequently ligated.
Bracket positioning in the upper Maxillary central incisors anterior teeth • General guidelines: – The bracket slot must be parallel to the occlusal plane. The horizontal bracket components may also parallel the incisal edge if not worn down. – Place the bracket 4.0 mm from the incisal edge, midpoint of the incisal­gingival height of the bracket – Centre the bracket mesio­distally over the mid­developmental ridge
• Common errors: – Bracket angulation: If angulation is insufficient, root proximity and open incisal embrasure with gingivally­placed mesial contacts may result. If angulation is excessive, overjet may be increased. – Brackets placed too incisally (<4.0 mm) – Excess resin on the bracket base
Bracket positioning in the upper Maxillary lateral incisors anterior teeth • General guidelines: – The bracket slot must be parallel to the occlusal plane. The horizontal bracket components may also parallel the incisal edge if not worn. – Place the bracket 3.5 mm from the incisal edge, midpoint of the incisal­gingival height of the bracket. This will allow the lateral to be slightly above the desired occlusal plane for good alignment and function with the mandibular canine. – Centre the bracket mesio­distally over the mid­ developmental ridge. – Vertical tie wings must be parallel to the crown outline and/or the mid­developmental ridge
• Common errors: – Insufficient angulation: It is sometimes difficult to visualize its long axis, and also due to the variable morphology. It is a common error that the roots of lateral incisors converge towards the centrals. – Brackets placed too incisally: This is common in smaller, poorly shaped laterals. These teeth would be too high above the occlusal plane, and appear to be too short relative to the canine and central incisor. The contact areas would be too far gingival, compromising esthetics
Maxillary canines • General guidelines: – The bracket slot should be parallel to the final occlusal plane – Vertical tie wings must be parallel to the mid­ developmental ridge – Place the bracket 4.5 mm from the cusp tip – Centre the bracket mesio­distally over the mid­developmental ridge, which is mesial to the midpoint of the tooth. This must be verified from an occlusal view with a mirror before light curing.
• Common errors: – Bracket angulation and mesio­distal positioning: With the mid­developmental ridge located mesially and the convex shape of the crown, brackets are often seen placed too far distally, as many use the cusp tip as a reference for the horizontal centre of the crown. This can create rotational errors and prevent the proper alignment of interproximal contacts. – Brackets placed too incisally: This is common in canines that are not fully erupted.
GENERAL ORTHODONTIC INSTRUMENTATION FOR FIXED APPLIANCES
Examination kit • Cotton pliers. This instrument is used to hold brackets securely when placing them onto the tooth surface. • Explorer. In orthodontics, this is commonly used to remove elastics, in place of a scaler. In addition, it can be used to remove excess resin after bracket placement. • Mouth mirror. This is used to verify the MD position of the bracket
Bidirectional ligature director. This instrument is used to tuck metal ligatures under the archwire, to keep the ends free from irritating the soft tissue. Bracket height gauge. This is used to measure the distance from the occlusal/incisal surface to the bracket slot. Distal­end cutter. This instrument cuts the distal end of archwire while holding the cut end. Therefore, this can be used in an intraoral setting.
Mathieu plier. This is an instrument that locks (like a haemostat) and braces small metal parts. In general, they are used to hold and twist the ends of metal ligatures, and also to place elastic ligatures. Ligature­cutting plier. To avoid damage to the instrument, these pliers must only be used to cut small gauges of “dead soft” stainless steel ligature wire (<0.014”) intra orally. Hard wire cutter. This instrument is designed to cut thick wire (> 0.014”) extraorally.
Ladmore composite instrument. This non­stick instrument is used to place resin onto the base of the bracket. Cheek and lip retractor. This is an adjustable device that retracts away the lips and cheeks to maximize visibility and to minimize salivary contamination. Debonding plier. This instrument is used to remove brackets by holding the bracket mesio­distally and applying slight pressure by torquing or turning in a clockwise motion.
References • • • • • • • • Sondhi, A. (2003). The implications of bracket selection and bracket placement on finishing details. Seminars in orthodontics, 9(3):155­164. McLaughlin, RP, Bennett, JC & Trevisi, H. (1999, Oct). Practical techniques for achieving improved accuracy in bracket positioning. The orthodontic CyberJournal. PAGE/VOL Swartz, ML. (YEAR). Achieving a 97% bonding success rate. (JOURNAL NAME). (VOL/NUMBER): PAGES. Swartz, ML. (YEAR) Brackets and bracket placement. (JOURNAL NAME). (VOL/NUMBER): PAGES. Proffit, WR. (2000). Contemporary Orthodontics. (3rd ed). St. Louis: Mosby. 397­400. Graber, TM & Vanarsdall, RL. (2000) Orthodontics Current Principles and Techniques. (3rd ed). St. Louis: Mosby. ch12. Isaacson, KG & Williams, JK. (YEAR) An introduction of fixed appliances. (3rd ed). London: John Wright & Sons Ltd. ch 4­5. Bennett, JC & McLaughlin RP. (1993) Orthodontic treatment mechanics and the preadjusted appliances. London: Wolfe Publishing. 55­64.
Acknowledgments • • • • Dr. Jean­Marc Retrouvey Dr. Daniela Frey Mr. Mike McHugh Instructional Multimedia Services of McGill University