Surgeons Referral Manual

Easy Skeletal anchorage

Written by: Don McGann, DDS (posmcgann@aol.com)

Contents:

1. Piriform rim upper anterior intrusion2. Lower anterior intrusion3. Minimum anchorage with bilateral bone plates4. Zygoma ligation (anchorage or growth management)5. Lower molar ligation: (anchorage or growth management)6. Palatal distalization7. Occlusal plane cant correction8. Midline correction (one arch)

Background:

Your referring Doctor has been trained in the use of [easy] skeletal anchorage to improve the qualityof orthodontic treatment. Don McGann, the writer of this manual and the founder of ProgressiveOrthodontic Seminars (POS), has developed a complete system of skeletal anchorage, which primarilyuses bone plates, but occasionally an orthodontic anchor (TAD), to support orthodontic forces. Theadvantages include control of the vertical dimension plus control of molar anchorage (resistance totooth movement) in more severe cases. The development started in 1998 with the first placement ofscrews and bone plates in patients, and has since been utilized in 1000s of patients worldwide. Thetopic has been divided into the ‘easy’ and ‘difficult’ skeletal anchorage jobs. The difficult jobs have moreinvolved surgery and/or more complicated orthodontics to utilize the anchor.

Bone plates are generally preferred over TAD screws since the line of force can be better controlled,multiple screws can be used to support the force, the force can be applied closer to the bone (similar tohanging a picture on the wall), and the location of placement is much more flexible. It is my opinion thatcancellous bone does NOT count in the retention of the screws, that the cortical bone layer is the onlyanatomy that is of retentive importance. I would like a minimum of 1mm cortical bone to support theforces being applied.

The discussion that follows is intended only as a reference, to facilitate the best relations andcommunication between the POS referring dentist and the maxillofacial surgeon. I have outlined how Ipersonally manage skeletal anchorage in these specific areas, bridging the needs of the orthodontictreatment with the surgical treatment. I have tried to show you every complication, so you canunderstand the issues and the full scope of the process, not just the placement of the screws and boneplates. You are welcome to change any of the surgical protocols as you wish, as I have never completeda surgery residency. I am a general dentist, with significant experience delivering skeletal anchorageservices since 1998, which was very early in this field. There were no protocols, there were only bone

plate products available, and there were no supporting orthodontic mechanics. These had to beinvented. I hope this document will shorten for you the learning process that I experienced.

Materials:

You can use any bone plate/screw materials you have in your practice. I generally do NOT wantelegantly designed titanium materials that will osseo-integrate. This only complicates the removal ofthe materials after the orthodontic usefulness is finished. The materials will be in the mouth for up to 2years. Having multiple brands of screws can become complicated if you do not have the specificscrewdriver to engage the screw head come time for removal. Note: since orthodontic treatment canbe ‘years’, a certain proportion of the patients will move to a far-away location where the specialscrewdriver you use is unavailable. Documentation of what screws and brand were placed is a goodidea, letting the referring dentist also know this information. The screws I use can be removed with asimple screwdriver if necessary. I personally consider it OK to leave the bone plates and screws, cut andpulling the ligature, leaving the bone plate, although some patients may not accept this (when told by asubsequent treating dentist).

**head of this screw can be removed with a regular screwdriver, althoughthe manufacturer product is preferred. This is important if the patient moves from the area duringorthodontic treatment.

My personal experience has been mostly with ACE brand bone screws, plates, and orthodonticanchors (TAD). ACE assembled a kit for use by POS students that wish to place (and remove) their ownskeletal anchorage, working with me on the design. A list of these materials can be obtained bycontacting supplyorders@posortho.net. In my experience, using smaller diameter screws (Micro,1.5mm diameter) rather than larger diameter screws reduces the failure rate, but Mini plates and screwsystems should also work fine. Bone plates are also much more retentive than TADs in the upper arch.The screws I use are self drilling, but I still drill a pilot hole, so self tapping is OK if that is what you use.Shorter screws are preferred over longer screws in most applications, as the cortical bone is consideredthe only retentive structure, longer screws can only get into the way of tooth movement, or be screwedinto a tooth. 6mm long screws are the most common length used, although the end 2mm of the screwis not usable since it is the ‘drilling’ portion. 7.5mm length screws are used in the zygoma as the firstscrew, attempting to engage double cortical plate (sinus floor and lateral wall of maxilla) where possible.4.5mm screws can be used successfully, especially in the maxilla where the cortical bone layer is thin.

Again, the last few mm is not useful on self drilling screws, so a 4.5mm screw is effectively 1.5mm aftersubtracting the self drilling part of the screw and the bone plate thickness.

The purpose of the pilot hole is to determine the thickness and density of cortical bone at theproposed screw location, and to have a location for initial placement of the screw. In the system I use,0.8mm pilot holes are used for 1.5mm diameter screws in all locations except for the lower buccal shelfarea where the bone is especially dense. For the buccal shelf, we use a 1.1mm drill to drill the pilot hole,preventing screw fracture.

Anesthetic: I do all these procedures under local anesthetic (only), although some sedation will makethe patient (and operator!) more comfortable.

HOW TO: Specific Locations

1. Piriform rim upper anterior intrusion (very common)a. Reasoning: Upper anterior intrusion is most commonly done to manage anterior deep

bite to enable orthodontic mechanics. Some cases do not start with deep bite, butbecause of the magnitude of incisor retraction planned, deep bite problems arepredicted.

** too much intrusion, as he barely shows his upper teeth whensmiling. This should have been upper + lower anterior intrusion.

The second use is to correct gingival display. The alveolar bone and gingival tissuewill intrude at the same rate as the tooth intrusion, even in adult patients.

b. What the referring dentist provides the surgeon: documentation of the skeletalanchorage location desired for the intended line of force. In skeletal anchorageplanning, the line of force (from the coil) is EVERYTHING! This can be in the form of adrawing or an “X” marks the spot on a study model. A written description may sufficeafter each of you know what the other is doing, so simply saying “piriform rim betweenthe cuspid and lateral root” may be enough in those cases.

The 2 locations common in piriform rim intrusion is a) between the lateral and cuspidroots, 1-2mm from the superior of the piriform rim, and b) lateral to the piriform rim,sometimes as far posterior as “distal to the cuspid”. Distal to the cuspid is sometimeslimited by thin cortical bone and maxillary sinus location. So sometimes the decisionneeds to be made at the surgery.

HOW MUCH intrusion is planned. Is it 2mm or 6mm or more? For 2mm, not much cango wrong. If 6mm, the upper incisor will ‘flare’ out to the ‘advancing limit” of thebracket and archwire combination they are using. With a straight wire bracket this isvery proclined, with a damon bracket or Li IP bracket, the incisor long axis can be nearlyparallel with the floor!!!! With more than 5mm of intrusion, be sure your POS referringdentist has “La” or labial root torque brackets on the upper incisors to prevent this, thenif they plan to retract after intrusion and suspension, they can change to Li torquebrackets. If they do not know how much intrusion, look at them sideways.

If they plan on 5mm, which is probably the limit of “easy” intrusion, then you may getanterior bite opening. OK, you can always release the suspension and coils and use

vertical elastics, but really? Better to be sure there is at least that much deep bite tostart. If NOT, then the case may need anterior PLUS Posterior intrusion, and now thispushes the case into ‘complicated’ skeletal anchorage, only to be done with moretraining (section 4 in POS terminology).

c. Diagnosis: The same diagnosis you would do for “vertical maxillary excess”. Althoughthe diagnosis has likely been done by the referring dentist, you should know that theupper resting lip to the incisal edge is the critical ingredient to upper anterior intrusion,and this should be documented with a photograph before starting. Some patients mayhave gingival display on high smile, but the resting lip is the normal 1-2mm, so the upperincisors cannot be intruded. Then we look to the lower anterior to intrude if thereasoning is for deep bite control or correction.

d. When is the patient ready for surgery: If the planned intrusion is only 2-3mm, then thiscan be done very early in the case, even during the alignment stage (18x25N) to supportthe forces. This can be as early as 2 months after the brackets are bonded. If more than3mm intrusion is needed, then you will need to wait until a stiffer archwire is applied tothe brackets to prevent arch distortion (19x25ss). These cases will be ready for surgeryat about 1 year.

e. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) 0.8mm Pilot drill and slow speed handpieceb) blades,c) sutures,d) periosteal elevator(s),e) retractors,f) pickups,g) light wire plier to contour the bone plate if needed,

h) scaler to move the bone plate into position or twist the ligature wirearound

i) cotton pliers to pick up small items,j) screws,k) bone plates,l) 012 ligature,m) matheau plier or another plier to twist the ligature wire,n) pin and ligature cutters to cut the ligature wire,o) something to tuck the pigtail under the bracket.

Pictured below is the typical 2-hole bone plate with ligature looped frombone plate to nitie coil and then twisted to secure (end of this wire will bethe eventual suspension wire, attached to the archwire between 2-3 or 3-4.Then the coil, and a 2nd 012 ligature that will stretch the spring, attached tothe archwire. The screw goes into the open hole in the bone plate. Ofcourse get the flat side against the bone and the screw head into the otherbeveled side.

ii. Flap access: flaps are needed when placing bone plates, and I even don’t wantto place TADs without seeing what I am doing. PLUS, I want to know thethickness of the cortex and if not very good, then I make pilot holes in alternatelocations, picking the best. On the piriform rim, I have done most of the flaps asa horizontal incision at the mucogingival junction, from the cuspid to centralincisor, reflecting up to the piriform rim, then ‘lifting’ the tissue with theperiosteal elevator stabilized on the rim. As an alternative, you can use avertical incision, which I like on the lower intrusions, or vertical with a slighthorizontal releasing “L” flap. Your choice of course.

iii. Identifying anatomy: In this location, hard to go wrong since you have thepiriform rim as a reference.

iv. Pilot hole: made 1-2mm from the piriform rim with 0.8mm pilot drill in a slowspeed contra-angle handpiece. I have also used a ½ round bur in a high speedhandpiece with success. Think “density” and “thickness” of the cortex. Afterawhile you learn the ‘sound’ of lots of bone vs. thin bone. In some cases youcan get double cortical plate, floor of the nose on the other side. Nice!

v. Screw and place placement: assistant hands you the 6mm (or 4.5mm) screwwith 2-hole bone plate already on the screw. The coil has already been attachedto the bone plate and ready to go. The ends of the ligature are held on thehandle to assure the screw and bone plate are not “lost”. Screw is placed intothe pilot hole and secured. Simple, easy access.

** coil and bone plate positioned between cuspid and lateral (above)

*distal to cuspid on these photos (above), advantage of pulling “up and back”line of force. Usually this is more desirable line of force than the more anterior boneplate location, bone thickness and density permitting.

vi. Activation of the coil: you may want to require the referring dentist activatesthe coil, you passively ligating the coil to a bracket base as you would do withgold chain on an impacted cuspid. The referring dentist would appreciate,however, if you activate 150 grams per side the coil they provide (unless youwant to stock the 6mm, 9mm, 12mm nitie closed coils from PDS and use theactivation chart?). note: sterilizing nitie closed coils can change the property ofthe coil, especially if dry heat. **note: if possible, if there is enough attachedgingiva, then keep the coil outside of the mucosa. Less gingival irritation. If thisis NOT possible, as you need length to do the initial activation and additionallength to reactivate.Below: 5mm activation of the coil. Notice that the pigtails from bone plate tocoil have been cut, and will be in the tissue to cause irritation. To suspend, youneed another surgery.

vii. Closure: do I really need to tell you about this? I don’t think so. The only thingis that I do NOT worry about getting the tissue under the coil, under the boneplate, etc. Just suture with the tissue on top, yes not primary closure, but thebody is forgiving, to me also as a less than fully trained surgeon.

viii. Post-op: suture removal. Don’t expect any big problems.

f. Complications: upper incisor flaring (force pulling ‘up’ at a location away from thecenter of the tooth, the archwire), tissue irritation (worse when you clip the ligatureunder the tissue or place the coil under the mucosa, advise water irrigation device),screw failure (happens and then you need to replace it), do NOT expect significant rootresorption, anterior bite opening, and canting of the occlusal plane. That’s enough!

Above: ** Li advancing limit (above). You do NOT want this, obviously.

Above: Upper left plate fails, right continues intrusion and occlusal plane cant results.Action that should be taken is to deactivate the right coil and suspend, replace left plateand coil to level, then resume bilateral intrusion as needed.

Above: anterior bite opening as the upper second molars were not banded. Canting ofthe occlusal plane from asymmetric force application right vs. left.

Above: right side coil had no irritation, left side had ‘severe’ tissue irritation.

g. Expected tooth movement: 1mm per month. Anterior bite opening can result withintrusions of more than 3mm, especially if the referring dentist does not band/bond allteeth in the upper arch (second molars). ALL the teeth connected by the archwire willintrude, more in the anterior than the posterior, but they still intrude!

h. Reactivation schedule: (of the coil). You should not be concerned with this, as this is thejob of the referring dentist. Just be aware that they need to keep the coil active, ornothing moves. The dentist will likely need to give local anesthetic to keep the patientcomfortable during coil reactivation. If they do not, then it is common for the coil to goinactive and tooth movement stop. Here is a list of millimeter activations of the nickel-titanium coils sold by PDS (coils from different suppliers will have a different force permm activation). It is typical to place 150 grams per coil for piriform rim intrusion, andwith 1mm per month tooth movement, you can figure out a reactivation schedule (lastmm does not count).

If YOU will be asked by the referring dentist to do the initial activation of the coil atsurgery, then ask them to provide the coil and use these coil extensions. It is BEST to usea gram gauge to be assured of the force being used, especially if you have manyreferring doctors with different coils. I use .012 steel ligature tie (on a spool) to securethe coils to the bone plate and archwire.

If the coil is fully activated to the archwire, then reactivation (stretching the coil to beactive again) must then be done by twisting the ligature wire to push the coil ‘apically’into the mucosal tissue…yes, you release the “suspension” wire from the archwire and

twist the coil apically….returning the suspension wire to the archwire position after…notfun, could take 30 minutes for 2 coils. If this needs to be done, expect your referralsource to ask you to do it!! THEN you learn to leave enough extra space for reactivationand demand from the referral source to tell you how much intrusion is planned!

i. Suspension: After the intended intrusion, and BEFORE retracting the incisors, theintrusion should be suspended. The coil will NOT be sufficient to prevent the incisorsfrom extruding again as they are retracted. This is where the ligature tie that attachesthe coil to the bone plate comes in handy. If you simply cut the pigtail of this ligatureand leave it under the tissue, there is a good chance for a major tissue irritation todevelop. Instead, by attaching this ligature to the archwire, you have a ‘ready to go’suspension wire. **note: it is common and good practice to retract and upper cuspidinto the bicuspid extraction space while the anterior intrusion is active.Suspension after upper anterior intrusion

j. Removal surgery: cut the coil and suspension ligature wire from the archwire with fine‘pin and ligature’ cutters, grab the ends of the coil and suspension wire with a hemostatand ‘shake’ the tissue from these parts. Sharp dissection ‘down the coil/ligature’ leadsto the bone plate location. Insert the screwdriver and remove the screws. Sometimesyou need to “pry” the bone plate from the bone, but do not expect the ACE products tobe covered by bone.

** note: with intrusions, especially the ones that get anterior open bite, the tendencywill be to remove the anchors and coils and close the bite with elastics. This moverapidly extrudes the previously intruded teeth, sometimes all the way to the startposition. My recommendation is to suspend in the open bite situation, and use verticalelastics to close the bite (lowers move to the upper). Also, do not forget to look at themolars to see if they are in contact, and should have been bonded.

** it is always safer to remove the plates and coils or suspension when the bracketsare removed, not before.

2. Lower anterior intrusion (common in the European deep bite, but often not

diagnosed correctly, it is natural to see deep bite and think upper incisor intrusion)a. Reasoning: The most common use of lower anterior intrusion is to correct deep bite.

The upper incisors cannot be intruded due to a normal resting upper lip. So the lowerteeth are intruded. Once diagnosed properly, lower anterior intrusion is generallyeasier than piriform rim upper intrusion. Good access, good thick mandibular bone tosupport the screw.

**lower incisor tips to the Roth advancing limit during intrusion.

b. What the referring dentist provides the surgeon: documentation of the skeletalanchorage location desired for the intended line of force, which in this location is almostalways “straight down”. This can be in the form of a drawing or an “X” marks the spoton a study model. A written description may suffice after each of you know what theother is doing, so simply saying “lower anterior intrusion with forces between the lateralincisor and cuspid on both sides” should be enough in these cases.

HOW MUCH intrusion is planned. Is it 2mm or 6mm or more? For 2mm, not muchcan go wrong. If 6mm, the upper incisor will ‘flare’ out to the ‘advancing limit” of thebracket and archwire combination they are using. But in the LOWER, this is not such aproblem, as seen on the extreme case shown above. The risk would be lower incisorstripping, but that does not seem to be a problem unless you start with ‘fragile’ gingivaltissue and you put the coils on top of the crestal tissue on the root.

With more than 5mm of intrusion, be sure your POS referring dentist has “La” orlabial root torque brackets on the lower incisors to limit the lower incisor flaring. Rothbrackets or worse Damon, have an advancing limit very proclined (see how the abovecase looks).

If they plan on 5mm, which is probably the limit of “easy” skeletal anchorage, then youmay get anterior bite opening, and in fact the entire lower arch will intrude, anteriorPLUS posterior!! Better to be sure there is at least as much deep bite as the intendedintrusion.

c. Diagnosis: Although the diagnosis has likely been done by the referring dentist, youshould know that the upper resting lip to the incisal edge is the critical ingredient toanterior intrusion, and this PLUS the lower lip to lower incisor should be documentedwith a photograph before starting. Our first choice is usually upper intrusion, but this islimited by the resting lip and smile (note over-intrusion in the case shown above in theupper anterior intrusion section). If the resting lip is the normal 1-2mm, the upperincisors cannot be intruded, and lower anterior is then the choice. Some cases NEEDBOTH upper and lower intrusion, as with the over-intruded upper referenced above.

d. When is the patient ready for surgery: If the planned intrusion is only 2-3mm, then thiscan be done very early in the case, even during the alignment stage (18x25N) to supportthe forces. This can be as early as 2 months after the brackets are bonded. If more than3mm intrusion is needed, then you will need to wait until a stiffer archwire is applied tothe brackets to prevent arch distortion (19x25ss). These cases will be ready for surgeryat about 1 year.

e. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) 0.8mm Pilot drill and slow speed handpieceb) blades,c) sutures,

d) periosteal elevator(s),e) retractors,f) pickups,g) light wire plier to contour the bone plate if needed,h) scaler to move the bone plate into position or twist the ligature wire

aroundi) cotton pliers to pick up small items,j) screws,k) bone plates,l) 012 ligature,m) matheau plier or another plier to twist the ligature wire,n) pin and ligature cutters to cut the ligature wire,o) something to tuck the pigtail under the bracket.

Pictured below is the typical 2-hole bone plate with ligature securing thenitie closed coil to the bone plate. The end of this wire will be the eventualsuspension wire, attached to the archwire between 2-3. After the screw issecure in the bone, a 2nd 012 ligature is added to the end of the coil tostretch the spring to the archwire. Of course be sure the flat side of thebone plate is against the bone and the screw head into the other beveledside.

Note: in lower intrusions, it is not likely there is enough attached gingiva tokeep the bone plate out of the mucosa, so the coil is usually attacheddirectly to the bone plate, the coil is accepted to be under the tissue.

ii. Flap access: flaps are needed when placing bone plates, and I don’t want toeven place TADs without seeing what I am doing. A vertical incision is the choicehere, using 2 periosteal elevators to ‘open the window’. I have also usedhorizontal incisions at the mucogingival junction, giving even more visualizationof the bone anatomy. I do NOT reflect the attached gingiva and papilla.

iii. Identifying anatomy: In this location, hard to go wrong since there is nothingmuch of importance that you can damage. In most cases it is preferred to placethe bone plate on the ‘chin button’, keeping the coil from rubbing directly onthe gingival tissue.

Above: ortho anchor (TAD) placed on the lower anterior to intrude. The coil isheld away from the gingival tissue (good), but the TAD is maybe too prominentin the soft tissue. A 2 hole bone plate placed a little more inferior on the chinbutton curve would serve the same purpose to keep the coil away from thegingival tissue.

iv. Pilot hole: 0.8mm pilot drill in a slow speed contra-angle handpiece. In thislocation, “density” and “thickness” of the cortex is not really an issue (easy!)

v. Screw and place placement: assistant hands you the 6mm screw with 2-holebone plate already on the screw. The coil has already been attached to the boneplate and ready to go. The ends of the ligature are held on the handle to assurethe screw and bone plate are not “lost”. Screw is placed into the pilot hole andsecured. Simple, easy access.

vi. Activation of the coil: you may want to require the referring dentist activatesthe coil, you passively ligating the coil to a bracket base as you would do withgold chain on an impacted cuspid. The referring dentist would appreciate,however, if you activate 150 grams per side the coil they provide (unless youwant to stock the 6mm, 9mm, 12mm nitie closed coils from PDS and use theactivation chart?). note: sterilizing nitie closed coils can change the property ofthe coil, especially if dry heat.

Determine the passive length of the coil to the archwire to be certain youhave enough space for reactivation of the coil (should be at least 2mm morespace between the coil and the archwire than the intended intrusion), thenactivate to 150 grams using the table or gram gauge.

** LONGER coils have a longer range of activation (they work longer betweenreactivations), so they are preferred. Placing the screw more inferior will enablea bigger space to activate and reactivate the coil. For example, if you place a6mm coil, 150 grams is +2mm stretch of the coil, so the coil will need to bereactivated in about 6-8 weeks. If you use a 12mm coil, then the same force is at+5mm stretch, and it will intrude up to 4mm.

vii. Closure: As you normally do, I will place sutures on horizontal incision, butsometimes not at all on vertical incisions.

**12mm coils stretched all the way tothe archwire (archwire passes through the loop of the coil)

viii. Post-op: suture removal. Don’t expect any big problems.

f. Complications: Lower incisor flaring (force pulling ‘down’ at a location away from thecenter of the tooth, the archwire), but this is NOT as much of a problem as the excessproclination of the upper. You can lose anterior overjet before the class II posterior iscorrected, but that is about as bad as it gets. Tissue irritation is always a possibility, butfor some reason the lower does not seem to have as much problem as the upper, butstill do not clip the ligature under the tissue. Screw failure can happen, but is lessfrequent than on the upper since the bone is thicker and denser on the mandible.Asymmetric intrusion is another possibility associated with screw failure, which is notalways obvious.**Gingival recession: is the main complication that you want to avoid. Do NOT place thecoils over the gingival crest. On the case below, the patient had fragile tissue throughoutthe mouth and the irritation from the coil was severe.

Below: asymmetric lower intrusion from screw failure. The failed screws were found bycomparing the coil activations on a periapical x-ray. Once the problem found, thecorrection was simple.

g. Expected tooth movement: 1mm per month. Anterior bite opening can result withintrusions of more than 3mm, ALL the teeth connected by the archwire will intrude,more in the anterior than the posterior, but they still intrude!

h. Reactivation schedule: (of the coil). You should not be concerned with this, as this is thejob of the referring dentist. Just be aware that they need to keep the coil active, ornothing moves. The dentist will likely need to give local anesthetic to keep the patientcomfortable during coil reactivation. If they do not, then it is common for the coil to goinactive and tooth movement stop. Here is a list of millimeter activations of the nickel-titanium coils sold by PDS (coils from different suppliers will have a different force permm activation, so you need a force gauge to service all the referral sources, unless youare the one supplying the coils?). It is typical to place 150 grams per coil for lowerintrusion. If YOU are asked by the referring dentist to do the initial activation of the coilat surgery, then ask them to provide the coil and use these coil extensions. It is BEST touse a gram gauge to be assured of the force being used, especially if you have manyreferring doctors with different coils. I use .012 steel ligature tie (on a spool that can beautoclaved) to secure the coils to the bone plate and archwire.

If the coil is fully activated to the archwire, then reactivation (stretching the coil to beactive again) must then be done by twisting the ligature wire to push the coil ‘apically’into the mucosal tissue…yes, you release the “suspension” wire from the archwire andtwist the coil apically….returning the suspension wire to the archwire position after…notfun, could take 30 minutes for 2 coils. If this needs to be done, expect your referralsource to ask you to do it!! THEN you learn to leave enough extra space for reactivationand demand from the referral source to tell you how much intrusion is planned!

i. Suspension: After the intended intrusion, the segment should be suspended. Use theligature wire that attached the coil to the bone plate as your ‘ready to go’ suspensionwire. If you cut the pigtail under the tissue, you will need another surgery to attachsuspension wires from the archwire to the bone plate. Last time you will do that! I’vebeen there. In the lower, the incisor root may have ‘torqued’ back to hit the lingualcortical plate, so retraction may NOT happen, if this is in the treatment plan!

j. Removal surgery: cut the coil and suspension ligature wire from the archwire with fine‘pin and ligature’ cutters, grab the ends of the coil and suspension wire with a hemostatand ‘shake’ the tissue from these parts. Sharp dissection ‘down the coil/ligature’ leadsto the bone plate location. Insert the screwdriver and remove the screws. Sometimesyou need to “pry” the bone plate from the bone, but do not expect the ACE products tobe covered by bone.Below: removal

3. Minimum anchorage (bilateral) with anterior bone platesa. Reasoning: Moving molars forward to replace a lost or extracted lower first molar

without disturbing the lower anterior is really only possible with skeletal anchorage. Ihave tried several approaches over the years. I started with single pins (before TADs hitthe market) which resulted in big line of force problems. Next I changed to straight or Yplates in the lower cuspid/bicuspid area, and some of those failed. There was also therisk of bagging a mental nerve when this is applied to a large group of providers. Finally Isettled on the lower anterior as the best place for the anchorage, and this was easieraccess and safer when considering the masses doing the procedure.

To do this, use 8 hole straight bone plates as pictured below. The last moduleis located near the bottom of the cuspid bracket, so the coil from the molar isnear parallel to the occlusal table. 2 screws in the generally solid mandible isusually sufficient to support the 200 grams per side that is applied. Micro platesare used, but Mini also would work with greater rigidity of the plate.

The plate can also be ‘double’ used to intrude the lower anterior, placing a closed coilfrom the bone plate to the lower anterior teeth as shown below.

Other designs in the past (learn from them, why NOT)

The plate below is attached too high on the alveolar bone, the cortical bone layer beingless thick and dense the more occlusal the position. Another case with a failed boneplate. The forces pull the plate ‘over’, a failed plate. BUT, in those days we were NOTdelivering the force as well as today, generally overloading the bone plates with moreforce than what was needed to move the teeth. Today, when I apply forces lateral tothe end of the bone plate, I use a T or Y with 3 screws.

Below: “substituting” a broken down lower right first molar with the 7+8.

Below: line of force is good, and the Y plate will resist the tipping moment, but thescrews are too close to the mental nerve for mass application

Below: Lower arch advancement with 17x25 segmental wire and nickel-titanium closedcoil that is activated by a ligature wire from an ortho anchor. Amount of wire extendinganterior shows activation (10mm open coil, activated 2mm = 150 grams). This proved tobe too difficult for everyone to do, plus the activating ligature wire had too muchflexibility. Not to mention that the placement of the ortho anchor had to avoid rootsand the mental nerve.

b. What the referring dentist provides the surgeon: documentation of the proposed toothmovement (minimum anchorage from the molars to move the molars and/or the entirelower arch forward). The intended line of force, which in this location is almost always“straight forward”. A written description may suffice after each of you know what theother is doing, so simply saying “bilateral lower molar (arch) advancement of “Xmm””.The amount of advancement needed is not really so much of a concern in this type ofskeletal anchorage application, since the coil is outside the tissue and can easily bereactivated. It is simply a matter of time.

This type of tooth movement historically has had problems with the molar notmoving forward due to unwanted tooth movements. POS referral sources will have a“UP” molar tube variation PLUS they will be using a 19x25ss archwire to move the teethbetween the cortical plates. This combination has solved those problems, and they canmove molars as far forward as they want, just takes time! I would not recommend thisdiagnosis for referral sources with traditional brackets unless the orthodontist is skilledat controlling the unwanted tooth movements with archwire adjustments.

c. Diagnosis: There is not much to diagnose in these cases, except the referring dentistmust plan on the amount of molar advancement, and the ‘easy’ skeletal anchorage islimited to bilateral molar advancement. Just be careful that the line of force of the coilis approximately parallel with the occlusal plane. If you are planning unilateralminimum anchorage, then this requires more training since there are morecomplications, so stay with the ‘easy’ bilateral cases unless you know your referringdentist has had that additional training. On the unilateral cases, encourage them torestore the missing molar.

d. When is the patient ready for surgery: Wait until a stiff archwire is applied to thebrackets to prevent arch distortion (19x25ss) to control the unwanted tooth movements

along with the bracket design. These cases will be ready for surgery at about 1 year afterthe brackets are placed. You can place the bone plate a few months earlier than the coilactivation, since the plate protrudes out of the gingival tissue. The coil can therefore betied to the bone plate at any time the case is ready.

e. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) 0.8mm Pilot drill and slow speed handpieceb) blades,c) sutures,d) periosteal elevator(s),e) retractors,f) pickups,g) light wire plier to contour the bone plate if needed,h) scaler to move the bone plate into position or twist the ligature wire

aroundi) cotton pliers to pick up small items,j) 6mm screwsk) bone plates, 8 hole x2l) 012 ligature,m) matheau plier or another plier to twist the ligature wire,n) pin and ligature cutters to cut the ligature wire,o) something to tuck the pigtail under the bracket.

**you may NOT place the coil atsurgery, which will make the procedure much simpler. Let the referring dentistplace the coil since the plate typically protrudes from the gingival tissue.

ii. Flap access: Horizontal incisions at the mucogingival junction are my choice forthis application, giving good visualization of the bone anatomy. I do NOT reflectthe attached gingiva and papilla.

iii. Identifying anatomy: In this location, hard to go wrong since there is nothingmuch of importance that you can damage. The final location of the bone platefor the eventual coil attachment is usually what dictates where the screws areplaced and how the bone plate is contoured.

iv. Pilot hole: 0.8mm pilot drill in a slow speed contra-angle handpiece. In thislocation, “density” and “thickness” of the cortex is not really an issue (easy!)

v. Screw and place placement: assistant passes screws after you position the boneplate and make your first pilot hole (or self drill). I use 6mm screws for this.Nothing you have not done a 1000 times before in trauma cases.

vi. Activation of the coil: have the referring dentist place the coil. Send the patientback with the bone plate protruding outside the tissue just below the cuspidbracket.

vii. Closure: As you normally do, I will place continuous sutures on horizontalincision, your choice of material.

viii. Post-op: suture removal. Don’t expect any big problems.

f. Complications: Screw failure can happen, but is less frequent than on the upper sincethe bone is thicker and denser on the mandible. The MAIN complication is canting ofthe occlusal plane (usually unilateral applications as seen below), and bite opening withunplanned lower molar and incisor protrusion. Line of force is everything! For thisreason, I ONLY suggest bilateral minimum anchorage plans for the “easy” skeletalanchorage dentist.1. Below: single screw placement (TAD) with poor line of force, to advance the lower

molar results in canting of the entire occlusal plane and tips/intrudes the molar.

2. Bite opening: Anterior bite opening as a result of “down and forward” line of force.Line of force: is critical in ALL skeletal anchorage applications, and is the reason that I do NOTuse many ortho anchors (TADs). If the coil is pulling ‘DOWN’ on the lower molar beingadvanced, the entire lower arch can intrude, AND the lower incisors can advance, opening thebite. Note that the molars AND incisors intruded even though the coil was ‘only’ pulling on themolar and bicuspid. The ENTIRE archwire is intruded, as are any of the teeth attached to thewire. Note how the root of the lower incisor is pushed against the lingual cortical plate. Thesesame principles apply upper and lower.

g. Expected tooth movement: 1mm per month.h. Reactivation schedule: (of the coil). Referring dentist does this and no local anesthetic

should be needed. Simple.i. Suspension: none.j. Removal of the bone plates: Sharp dissection ‘down the bone plate’ leads to the

screw` location. Insert the screwdriver and remove the screws. Sometimes you need to“pry” the bone plate from the bone, but do not expect the ACE products to be coveredby bone.

4. Zygoma Ligationa. Reasoning: upper molar anchorage, or growth management to prevent movement

forward of the dento-alveolar arch of teeth and bone (moves independent of the maxillato follow the extra growth of the mandible and make space for erupting 7+8s (McGann).

Upper Molar anchorage: is about preventing the upper molar from moving forward,usually when closing upper [bicuspid] extraction space. This may be the needed‘anchorage’ in the upper arch of a class II case. The referring dentist wants to retract theupper anterior teeth, keeping the upper molars stable. Pictured below, a singleorthodontic screw has been placed in the zygomatic buttress to stabilize the molar onthe picture on your left and to support molar distalization on the picture on the right.Notice that the ligature tie from the TAD is tied to the bracket base of the bicuspid. The‘loop’ on the left picture is not as desirable since this can mean loose wire and toothmovement allowed. A 2-hole bone plate with one 7.5mm screw can also be used as analternative to the ortho anchor.

Growth Management of the upper arch, preventing the mesial migration of the teethand alveolar bone surrounding them is a concept developed by me (McGann) after studying 650growing cases. The upper teeth and alveolar bone move independent of the maxilla, and followthe extra growth of the mandible (differential horizontal growth). The most effective, non-compliant method to manage this, in the process correcting class II dental, is to ligate thezygomatic buttress to the anterior teeth. I call this zygoma ligation. The typical patient will beearly adolescent, pre-pubertal or pubertal, and have supporting documentation of their stage ofgrowth as part of the treatment plan.Below: 2 hole bone plate with “L” flap access to the zygomatic buttress, with one screw securedinto the zygomatic buttress. 012 ligature twisted and secured to the bracket base of the lateralincisor. Stainless steel coils maintain the space for the erupting cuspid and prevent mesialmigration of the upper molar. NO coils, nothing is done, just wait for the growth to do the work,the lower jaw and teeth to catch up. **placement of the screw must be in the zygomaticbuttress, preferred double cortical bone of the sinus floor and zygoma. Feel anatomy where ittransitions from vertical to horizontal, place the screw in the ‘horizontal’ portion as the verticalis the dento-alveolar bone that we are trying to stop from moving!

a. What the referring dentist provides the surgeon: There is nothing to provide except tosay “ligate the cuspid bracket base to the zygomatic buttress”. The surgeon simplyneeds to place the screw in the zygoma, not the dentoalveolar bone. It would be nice ifthe dentist has a frontal ceph to provide that as a reference of the anatomy (see below).The POS trained dentist will have a growth prediction showing the expected change inthe occlusion and documentation of the stage of growth, including1) Wrist x-ray2) Cervical vertebra maturation3) Height measurements4) Documentation of menarche and breast development in girls, and voice dropping

plus hair development in boys.

Diagnosis: Nothing for you to do.

b. When is the patient ready for surgery: immediately upon referral. Do NOT delay. Theseare time sensitive cases, every month lost is a loss in some growth management.

c. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) 0.8mm Pilot drill and slow speed handpieceb) Blade (15),c) sutured) periosteal elevator(s),e) retractors,f) pickups,g) light wire plier to contour the bone plate if needed,h) scaler to move the bone plate into position or twist the ligature wire

aroundi) cotton pliers to pick up small items,j) 7.5mm screwsk) bone plates, 2 hole x2 (OK to cut a 4 into two twos)l) 012 ligature,m) matheau plier or another plier to twist the ligature wire,n) pin and ligature cutters to cut the ligature wire,

o) something to tuck the pigtail under the bracket (suggest ligaturedirector)

ii. Flap access: the L flap is my preferred access. Palpate the zygomatic buttressand make a vertical incision on the anterior aspect, ending at the mucogingivaljunction. Then make a horizontal incision from that point more posterior.Reflect the flap (very easy and great access).Below: “L flap” with the inferior periosteal elevator pointing to the intersectionbetween vertical and horizontal anatomy. The pin should be placed LATERAL tothat point, definitely not inferior.

iii. Identifying anatomy: reference the cortical plate intersection on a frontal cephand by palpation of the inferior zygomatic buttress anatomy. We want toengage the sinus floor cortical bone, where possible. Thus the use of a longerscrew. 10mm would also be ok.

iv. Pilot hole: 0.8mm pilot drill in a slow speed contra-angle handpiece, pushed allthe way in, feeling for a 2nd cortical bone layer. Occasionally, the bone here isvery dense and thick. If so, then use a 1.1mm pilot drill to prevent screwfracture.

v. Screw and place placement: 7.5mm, but this can be variable according to thedensity of the bone and presence of double cortical plate.

vi. Activation of the coil: none, no coilsvii. Closure: As you normally do, I have simply used 1 or 2 sutures maximum to

place the flap on top of the plate and ligature.viii. Post-op: suture removal. Don’t expect any big problems.

b. Complications: since there is no force applied to the screw through coils, there is reallynothing to go wrong except tissue irritation, which is minimal without a coil. Theligature will be ‘in’ the tissue, not visible after a short time. It will stay there for 1-3years. In the event that the growth is less than expected, a coil may be added to theligature wire at a future date after all the growth is nearly finished.

Below: Ortho anchor (TAD) to stop the upper teeth from drifting forward and following mandibulargrowth.

**2-hole bone plate, 7.5mm screw, “L” flap, ligation to the lateral incisor bracket base.

5. Lower molar ligation:a. Reasoning: lower molar anchorage, or growth management to prevent movement

forward of the lower arch.Lower molar anchorage: A 6mm ortho anchor (or 2-hole bone plate with 6mm

screw) is placed in the buccal shelf, more posterior to the lower molar to be stabilized(usually the first molar). The anchor will not be in attached gingival as is preached bymany it must, but will be in soft tissue. The anchor MUST be placed more posterior tothe tooth to “hold the molar back”, but is limited by the soft tissue anatomy. Place ittoo far back and too much tissue irritation can result. Do NOT place the stabilizinganchor ‘inferior’ to the molar you are trying to stabilize or it will not prevent mesialmolar movement.

There is no coil, only the 012 ligature tie between the anchor/bone plate to theauxillary tube (‘double’ tube on the molar, called “pig” (for piggyback archwire) in thecustomized (individual patient) IP appliance® of POS. The 18x25 auxillary tube is moregingival to the archwire tube), as pictured below. It is best to ‘twist’ the ligature wirefrom the anchor to just distal of the tube to reduce wire flexibility and tissue irritation.Non POS referral sources will rarely have a ‘pig’ auxillary tube to work with so for these,ligate to the bracket base.

Growth management: During growth, and to a lesser degree throughout life, thelower molars drift forward, pushing the entire lower arch forward. This was discoveredby me when studying 250 growing cases in my growth study. The lower arch of teeth islikely moving forward to accommodate the eruption of the second and third molars(McGann).

In class III growing patients, we do not want the lower arch moving forward, soligation of the molar to the mandible is done to stop this. The bicuspids, cuspids, andincisors do not migrate forward on their own, it is the molar that is pushing themforward (McGann). The molar ligation may be there for several years, especially in boyswhich can grow late.

Below: molar ligation to the lower 6 “pig” variation in a class III growing boy. Notethat the second molars are partially erupted.

d. What the referring dentist provides the surgeon: The dentist should provide a growthprediction (line drawing) showing that the patient is not predicted to be an orthognathicsurgery case. For this ligation surgery, there is nothing to provide except to say “ligate

the lower 6 to the mandible”. The surgeon simply needs to place the screw in thebuccal shelf, and not in the dentoalveolar bone (wherever that transition is?).

The POS trained dentist will have a growth prediction showing the expected changein the occlusion and documentation of the stage of growth, including1. Wrist x-ray2. Cervical vertebra maturation3. Height measurements4. Documentation of menarche and breast development in girls, and voice dropping

plus hair development in boys.

The POS trained dentist will also have a surgical VTO (visual treatment objective)showing that surgery was considered in the diagnosis.

e. Diagnosis: Skeletal changes are UNEFFECTED by this method of growth management.The mandible will continue to grow and is genetically determined (McGann). This iswhere the growth prediction of the referring dentist is important. Is the skeletal growthof the patient predicted to become an orthognathic surgery case or is it not? If YES,then holding back the lower arch of teeth may not be in the overall best interest of thecase, increasing the compensation and making the pre-surgical orthodontics moredifficult to establish enough anterior crossbite before surgery. By saying this, you arethinking of traditional methods. Maybe a genioplasty will be sufficient to make thepatient look good if the teeth are in a good occlusion? If it is the maxilla that will beinsufficient and the reason for the class III skeletal problem, is the referring dentist alsoincorporating reverse headgear treatment (protraction headgear), which is mosteffective at a young age.

The risk is that this growth management will be done on a patient that will needsurgery anyway after fully grown, and the pre-surgical orthodontic setup will be moredifficult. You may want to ask if the referring dentist has discussed this with the patientas part of the consultation process.

f. When is the patient ready for surgery: immediately upon referral. Do NOT delay. Theseare time sensitive cases, every month lost is a loss in some dental drifting.

g. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) 1.1mm Pilot drill and slow speed handpieceb) Blade (15),c) sutured) periosteal elevator(s),e) retractors,f) pickups,

g) light wire plier to contour the bone plate if needed, if a 2 hole plate isplanned.

h) scaler to move the bone plate into position or twist the ligature wirearound. ONLY if a 2-hole plate is planned

i) cotton pliers to pick up small items,j) 6mm screws, or ortho anchork) bone plates, 2 hole x2 (OK to cut a 4 into two twos), if plannedl) 012 ligature,m) matheau plier or another plier to twist the ligature wire,n) pin and ligature cutters to cut the ligature wire,o) something to tuck the pigtail under the bracket (suggest ligature

director)ii. Flap access: The flap you use every day for lower 3rd molar extraction.

iii. Identifying anatomy: same as you work with every day for lower third molarextraction. The pin must be posterior to the molar to be ligated. It is possiblethat the referring dentist will ask you to ligate a lower 7 (for anchorage).

iv. Pilot hole: 1.1mm pilot drill in a slow speed contra-angle handpiece, since thebone here is very thick and dense. Try using a self drilling screw without a pilothole or 0.8mm drill and you will experience screw fractures. Since using the 1.1mm drill with a 1.5mm diameter screw (micro), I have not had the problem offractures.

v. Screw and place placement: 6mm, no need for more in this area!

vi. Activation of the coil: none, no coilsvii. Closure: As you normally do

viii. Post-op: suture removal. Don’t expect any big problems.

h. Complications: since there is no force applied to the screw through coils, there is reallynothing to go wrong except tissue irritation, which is minimal without a coil. Theligature will be ‘in’ the tissue, not visible after a short time. It will stay there for 1-3years.

i. Removal: dissect to the bone plate or screw and remove. If the bone plate has been inthe mouth for 2-3 years, it may be osseo-integrated. Ortho anchors should not have thisproblem, being made with more stainless steel, but it is possible you will fracture thescrew, removing the head only.

6. Palatal Distalizationa. Reasoning: Distalization of the upper arch can be done from the palate or from the

zygoma buttress. From my experience, I have placed zygomatic buttress skeletalanchorage with active mechanics (coils) in the more complicated category of POStraining. But this palatal distalization is easier to accomplish, so I have placed this intothe “easy” skeletal anchorage category.Below: Two ortho anchors are placed to a lab made palatal bar, extending anterior, with‘loops’ to attach 6mm (or 9mm) nitie closed coils. The line of force is very favorable, ‘upand back’, which will counter the frequent open bite problem in distalization cases. Theupper 7s were extracted to accommodate the first molar distalization. Notice that theupper molar moved ‘up and back’ on the overlay describing the action of this appliance.The panoramic is +1 year later (age 16 male) showing the eruption progress of the upper8s.

b. What the referring dentist provides the surgeon:i. The patient with palatal bar with loop(s) in place

ii. 6mm and 9mm closed coilsc. Diagnosis: If you have access to a CBCT scan, then establish palatal bone thickness for

finding the best location. Nothing much for you to diagnose in this type of case. Expectclass II molars.

d. When is the patient ready for surgery: immediately upon referral. The distalization isindependent of the archwires engaged and the other bracketed teeth.

Below: the heads of these two anchors should be seated fully into the tissue, against the bone.The coil should have been attached BEFORE screwing them in since this now is a challenge tothread the ligature threw the head and ligate at the back of the mouth! Flowable composite onthe screw head to cover the attaching pigtail. On the far right, notice the successfuldistalization, evident from the space between incisive papilla and the anterior palatal bar. Notethat one screw failed, but the remaining screw finished the job.

e. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) 0.8mm Pilot drill and slow speed handpieceb) Tissue punch (2mm)c) scaler to move the coil into positiond) cotton pliers to pick up small items,e) 8mm ortho anchorf) 012 ligature to attach the coil to the ortho anchor, optional, but it may

be easier on you if you have 010 ligature (used in orthodontics to tiearchwires to brackets) to ligate the anterior of the coil to the palatal bar.It will be just as easy for you to activate the coil when you place theanchors, so do this 2mm per coil, not overloading the anchors. Reporthow much activation you added and from that point, the referringdentist should take over the reactivation responsibilities.

g) matheau plier or another plier to twist the ligature wire,h) pin and ligature cutters to cut the ligature wire,i) something to tuck the pigtail under the palatal bar (suggest ligature

director)

j) flowable composite to cover the ligature pigtail at the anchor to preventtongue irritation. Optional, your referring dentist can do this later.Attach the coil to the anchor BEFORE inserting, and tuck the end of thepigtail in one of the extra holes in the head of the anchor.

ii. Identifying anatomy: In young patients, avoid placing screws in the ‘wide’midpalatal suture. The anchors will definitely fall out when place there. Thebone immediately lateral to the midpalatal suture may be thick and a goodplace to place the anchor. If you have a CBCT scan, bone thickness would begood to establish before surgery. It goes without saying, avoid the greaterpalatine area.Below: this anchor failed 3 times, and replaced 2x in a 3 month time periodbefore finally giving up. The overlay shows molar distalization (crown tipping isnot desirable) and intrusion despite the problems of keeping the anchor inplace.

iii. Punch: If you place the anchor at the midline, where the tissue is thin, you maynot need a punch. BUT if you place the screws lateral, then you will need apunch to allow the anchor head to be seated against the bone. YES, place thehead of the screw all the way into the tissue, if possible, and you will have lessscrew failures. The tongue and food shake the screw head, if exposed, leadingto frequent loss of screws. This is the main complication.

iv. Pilot hole: 0.8mm pilot drill in a slow speed contra-angle handpiece, only if youhave first made a punch hole. You may want to try self drilling the screw toplace without first making the punch, but then the screw head will NOT be ableto be seated all the way against the bone.

v. Screw and place placement: 8mm is what I have used, but that is not to say that6mm or 10mm would not be ok.

vi. Activation of the coil: add 2mm of activation ONLY at surgery. Inform thereferring dentist you did this.

vii. Post-op: not neededf. Complications: Loss of the screw or loosening to where it will not support the force.

This is frequent in the palate. Expect it! Tell the patient to expect it, especially if theyplay with the coils or screw with their tongue. Tell them to eat their food on the “side”where their teeth are, avoiding the palate where possible. Place 2 screws so if one islost, the other is still working.

g. Removal: Hopefully you will have to remove them! Simply unscrew.

7. Occlusal plane cant:a. Reasoning: It is possible to unilaterally intrude the upper teeth, and with this intrusion,

the gingiva will follow the tooth, evening the gingival display right vs. left.b) Additional records: that should be obtained either by the referring dentist or yourself.

1. photograph documenting the starting condition of the smile showing more gingivaon one side than the other,

2. a tongue blade between the teeth,3. a frontal ceph: showing an occlusal plane cant AND more vertical on the side to be

intruded (zygoma plane to antegonial notch).4. CBCT when available.5. TM joint evaluation: the joint on the intrusion side may be compressed in the fossa

Above: Double 6mm coils used on the right side only. This can be limited by the cortical bonethickness in this area, so an alternate method is to use a straight or Y plate from the zygoma,extending anterior (and from lateral piriform rim extending posterior) to support the coil. Lineof force is ‘straight up’.

a. What the referring dentist provides the surgeon:i. The additional records listed above, documenting the unilateral

intrusion is appropriate.ii. 6mm nitie closed coils

iii. The amount (mm) of planned intrusion (affects location of bone plateplacement and reactivation schedule).

iv. ALL upper teeth banded or bonded (including 7 or 8) in the quadrant tobe intruded. If 3mm or less intrusion, 18x25N is sufficient to supportthe intrusion, but 19x25ss is preferred to avoid arch distortion.

b. Diagnosis: The mandible will ‘auto-rotate’ with the unilateral tooth intrusion,assuming the teeth on that side stay in occlusion (by themselves or with theassistance of vertical elastics). For this reason, there should be a frontal ceph inthe diagnosis establishing an occlusal plane cant, tilting to the side you want tointrude, plus the measurement of Zygomatic plane to antegonial notch shouldbe longer on the side you wish to intrude. Notations of a TM joint exam beingdone and when available, a CBCT added to the records and diagnosis.

c. When is the patient ready for surgery: If the intrusion is only 2-3mm, then thiscan be done on 18x25N alignment wire (nothing smaller, and no roundalignment wires). If the intrusion is more than 3mm, then you should wait untila stiff 19x25ss archwire is engaged to prevent distortion of the archform. Also,when more than 3mm, I would recommend a palatal bar be placed to preventunilateral flaring of the bicuspid and molar crowns! To do this, make a palatalbar to goshgarian sheaths, and activate the double-back bend on the oppositeside that you do NOT want to be affected so that the palatal bar give ‘buccalcrown tip’ when seated on the intrusion side (when the bar is inserted only onthe non intrusion side, the double-back bend is superior to the molar on theintrusion side. This will also result in some extrusion on the ‘good’ side, withpossible bite opening. That’s right, more than 3mm intrusion is morecomplicated.

**If this is too complicated, then simply place a palatal bar as seen on the photobelow. Note the changes with the palatal bar on the ‘good side’.

d. The surgery:

i. Presurgical preparation: first have all the instruments needed for thesurgery, including

1. Pilot drill and slow speed handpiece2. Blade (15),3. suture4. periosteal elevator(s),5. retractors,6. pickups,7. light wire plier to contour the bone plates if needed,8. scaler to move the bone plate into position or twist the ligature

wire around.9. cotton pliers to pick up small items,10. 6mm screws, 7.5mm screws if you plan to engage the zygomatic

buttress.11. bone plates,12. 012 ligature,13. matheau plier or another plier to twist the ligature wire,14. pin and ligature cutters to cut the ligature wire,15. something to tuck the pigtail under the bracket (suggest ligature

director)ii. Identifying anatomy: lateral piriform rim and zygomatic buttress will

have the best bone for plate retention, but you may also find somecases will have sufficient bone in-between.

iii. Pilot hole: 0.8mm pilot drill in a slow speed contra-angle handpiece, toidentify bone thickness and density, plus to reduce stress on the boneas the screw is inserted.

iv. Screw and place placement: 6mm or even 4.5mm in areas of thin bone.Bone plates can be “L”, “T”, “Y”, or often I will shorten the Y to be a 3hole triangle, 2 screws on the sizes, the coil attachment to the middlehole (below) OR 3 screws and coil attachment to the 4th hole of the Y.

v. Activation of the coils: The surgeon can activate the coils at surgery (ortie off passively to the bracket base, the referring dentist activates),adding ‘only’ 3mm to 9mm coils, 150 grams per coil (or 6mm, +2mm, ifdistances are short). Reactivation by the referring dentist with localanesthetic. This is an easy area to work and reactivate coil by tighteningthe ligature extended to the archwire.

vi. Suspension: after intrusion is completed, and orthodontics is finishing.Do NOT remove the palatal bar until the brackets are removed….unlessthe ‘good side’ has a problem you have to fix.Below: suspension wires and coils have been deactivated as verticalelastics are used to tighten up the bite.

vii. Post-op: suture removal. Don’t expect any big problems.

c) Complications: bone plate failure due to insufficient bone thickness. Dental open bite,usually because the 7s were not bonded, and these teeth remain in contact with thelower teeth, preventing autorotation of the mandible to follow the intrusion. Thephoto below shows the recovery if the crowns flare buccal from the intrusion…palatalcoil!! Don’t go there, place the palatal bar, even if the good side tweeked a little.

d) Removal: dissection and screw removal. Nothing special.

8. Midline correction (one arch)a. Reasoning: especially in cases with a big dental asymmetry at the start, it is occasionally

near impossible to get the upper midline centered in the face OR the lower midlinemoved to the position you wish, without disturbing the ‘good’ arch. Skeletal anchorageis the answer to these one arch midline shifts. A unilateral bone plate is placed tosupport a coil force, which is very effective in moving a segment of teeth.

Below: Lower (only) midline shift corrected by the unilateral closed coil applied from theincisors to the bone plate. Notice the change in horizontal overjet of the upper left cuspid tothe lower left cuspid. ALSO, notice where the bone plate is relative to the cuspid bracketbefore and after. YES, there is intrusion whenever the coil is applied at an angle with verticaland horizontal vectors, count on it. The anterior cross elastic may be used to center the uppermidline to the left, but will disturb the lower midline since the coil has been removed (nosuspension to the bone plate).

b. What the referring dentist provides the surgeon: The request for unilateral bone plateplacement with VERY SPECIFIC instructions on where the force (coil) is to be attachedfor the intended line of force. BEST to give a study model to the surgeon with a big “X”where the coil will be attached to the bone plate. The surgeon then must figure out away with the available bone plates and bone anatomy to provide an anchor at thislocation. Line of force is everything, and takes precedence over screw and bone platelocation. Be certain to allow enough length from the bone plate ‘end location’ to wherethe dentist is attaching the coil! How far are you moving the teeth and is there room forreactivation with the smallest (6mm) coil?

c. Diagnosis: After the surgeon knows where the referring dentist needs the force applied(line of force and sufficient space for coil activation and reactivation to get the intendedtooth movement), he/she must plan the location and configuration of the bone plateand screws.

d. When is the patient ready for surgery: As soon as an archwire of sufficient stiffness toresist the force applied without distortion. 18x25N is sufficient to support the force andso is 19x25 ss.

e. The surgery:i. Presurgical preparation: first have all the instruments needed for the surgery,

includinga) Pilot drill and slow speed handpieceb) Blade (15),c) sutured) periosteal elevator(s),e) retractors,f) pickups,g) light wire plier to contour the bone plate if needed, if a 2 hole plate is

planned.h) scaler to move the bone plate into position or twist the ligature wire

around.i) cotton pliers to pick up small items,j) 6mm screws,k) bone plates of planned configurationl) 012 ligature,m) matheau plier or another plier to twist the ligature wire,n) pin and ligature cutters to cut the ligature wire,o) something to tuck the pigtail under the bracket (suggest ligature

director)f. Identifying anatomy: Usually piriform rim on the upper, and lower labial bone anatomy

on the lower.g. Pilot hole: 0.8 mm pilot drill in a slow speed contra-angle handpieceh. Screw and place placement: 6mm or even 4.5mm depending on the area you are

placing the bone plate.i. Activation of the coil: Best to attach the coil to the bone plate, and passively

secure the other end of the coil to a bracket base. Let the referring dentistactivate the coil and establish the line of force.

j. Post-op: suture removal. Don’t expect any big problems.k. Complications: bone plate failure is possible. Communication between referring

dentist and surgeon results in the bone plate being in the wrong place for the neededline of force. Due to the wrong line of force, canting of the occlusal plane or biteopening.

L. Removal: as with other bone plates. Dissect and remove screws.

Example below: bone plate on the upper left from lateral piriform rim was used to move theupper right central across the midline of the maxilla to become the upper left central. Cuspidswere used as ‘lateral incisors”. The bone defect left from the accident with loss of teeth 21,22was corrected. Now in finishing with change in torque brackets and detailing. Note: line offorce on the closed coil is adjusted since the bone plate does not fully extend to the occlusalplane.

Final comments:I sincerely hope that this explanation of how I now see skeletal anchorage will help you and

your referral source avoid some of the problems I encountered during the development of thesystem. The tooth movements possible are nothing short of AMAZING, and this serviceextends the capabilities of tooth movement.

I will be writing another document for use by POS students with section 4 training, whichwill include more complicated skeletal anchorage, including

a) Coils from the zygomatic buttress,b) Unilateral molar minimum anchoragec) Palatal intrusiond) lower molar intrusion,

e) upper molar intrusion,f) multiple coils for total maxillary dental intrusion,g) open bite corrections, and intrusion with retraction at the same time).h) Skeletal anchorage with corticotomy (upper lingual, lower lingual, lower

buccal)

Respectfully,

Don McGann