(1)When bonding an incognito case if you choose to use maximum cure (reliance), a self-curingresin, the working time is very limited and variable, maybe 90 seconds maximum. It may be worthwhile to do a test mix to see how much working time you have available. If you feel that you are not yetquick enough to bond the entire arch in one go, you could consider cutting the indirect bonding tray in two with a scalpel, and bonding the arch in two separate pieces. Make sure that your assistant is preparing the section of the tray for the section of the arch that you are intending to bond first. Maximum cure is an unfilled resin and cleaning the excess resin off the teeth after the bond up is certainly easier and less time consuming than with a filled resin.
If you prefer to work at a more relaxed pace,you can use a dual cure resin like Nexus 3 (kerr dental) and of course you must remember to order a transparent tray. Nexus is a filled resin and requires more time and effort to remove the excess after the bond up.
It is important to check with floss after the bond up to ensure that none of the teeth are bonded together.
(2) It isworthwhile (with few exceptions) to order half occlusal pads in combination with the tubes (with easy insertion design) on all four second molars. The half occlusal pads serve both to both open the bite and aid the retention of the tubes on the second molars.The easy insertion design as the name suggests facilitates insertion of the archwires, and is helpful particularly for the larger dimension wires. For lower first premolars again a half occlusal pad with the bracket is helpful to minimise debonds,it is particularly important if treating a young patient (with incompletely erupted teeth).
(3) One must bear the configuration of the appliance in mind when considering the bio- mechanics. For the upper and lower canines and incisors the archwire is inserted vertically into the slot, Figures 1 and 2.
Figure 1
Figure 2.
It is inserted horizontally in the premolars and molars.
The vertical insertion slot facilitates the insertion of the archwire in the incisors and canines, and makes the correction of rotations straight forward. However thevertical slot configuration means that certain challenges are presented to the orthodontist which do not arise with the horizontal insertion slot (which we are all familiar with from labial orthodontics)
The correction of “tip” or “second order” needs extra consideration when using a vertical insertion configuration. Correction of tip in the levelling and alignment phase depends on the use of the correct tie/ligature. With a very tipped tooth a german overtie Figure 3 could be used with the round niti aligning archwire to start correcting the tip problem, (once any rotation problems have been resolved).
Figure 3. German Overties.
Once the first rectangular niti wire is reached a power tie can be employed to helpfurther correct second order problems in a very tipped tooth.
Figure 4 Power Tie.
(4) Always use a bracket rather than a tube on the molar next to the last premolar. The use of a tube in this situation makes the insertion of the large dimension wires particularly difficult.
(5) If you wish to treat a non- extraction case which has spacing present, which is more than 4mm in total , you should order archwires which are straight in the buccal segments (i.e. not individualised archwires ) , and only use an individualised archwire for the final finishing archwire .That is you essentially treat it as an extraction case. If one orders all individualised archwires in a case with spacing greater than 4 mm, there is a distinct possibility that the first order bends in the wire will prevent space closure due to interference with sliding mechanics.