Skeletal Anchorage Flashcards
The anchorage potential for each tooth, or groups of teeth is dependent on many factors, name some.
Area of the PDL surface
Health of periodontal attachment
Density and structure of the alveolar bone
Turnover rates of the periodontal tissues
Facial type
Muscular activity
Occlusal forces
Nature of the tooth Movement planned for the intended correction
What are some techniques to maximize tooth-related anchorage?
Differential torque
Placement of roots against cortical bone
Distal tipping of molars
True or false… restorative implants can be used as anchors in selected cases; however, they require careful planning prior to orthodontic treatment.
True
True or false… surface properties and design improvements have increased predicability which have shortened the healing time from 6 months to several weeks
True
Currently, the most predictable and acceptable implant material is ____ with some type of ___
Pure titanium
Subtractive surface treatment
What is the difference in indirect application and direct application in regard to TADs?
Indirect application - TADs can support the anchor teeth
Direct application - at as the reactive unit by being directly attached to teeth that the clinical wants to move.
TADs can be located on the surface of the bone ___, under the periosteum ____, or inside the bone ____, and can be fixed to the bone by either mechanically (____) or biologically (___).
Transosteal
Subperiosteal
Endosteal
Cortically stabilized, biointegration
Osseointegration
What makes the direct applications of implants and TADs challenging is the absence of….
Conventional reciprocal moments that would normally be cancelling each other, allowing linear movements along an archwire or bodily movements through segmental mechanics.
With TADs, newton’s third law still occurs, however…
All reactive forces with implants or TADs dissipate in the skeleton
With distalization of canines into extraction spaces with sliding mechanics with TADs, the compensating moments that normally cancel each other out are not present, which results in…
Unsolved rotational moments on the canines. This leads to a narrowing of the buccal segments, possibly creating posterior crossbite.
Palatal auxiliaries, such as trans palatal bars, should be considered in these situations
Palatal implant location choice should be carefully evaluated to avoid perforations of the ___
Inferior nasal turbinate
(The thickest bone (4-8mm) is found in the anterior part of the palate both in the median and paramedian areas of the suture
to avoid the midpalatal suture, the suitable area for implant placement in the posterior palate is located ___mm posterior to the incisive foramen and ___mm paramedian
6-9
3-6
Typically, adequate interradicular bone distances were found more than ___ down the root lengths, which are likely covered by unattached mucosa
Halfway
The inability to place mini-screws in attached gingiva may necessitate design modification or oblique insertion direction to decrease soft-tissue irritation
What type of imaging is necessary for placement of TADs?
A panoramic radiograph, is usually sufficient for establishing the accuracy needed for the identification of locations in the interradicular spaces
Although surgical guides may help, the general consensus is the ease and availability of the panoramic imaging along with the experience of the clinician are sufficient for most situations
Cone beam CTs are useful with palatal implants however
How is a palatal implant placed?
Local anesthesia is necessary
The drill sequence includes a tissue punch, a round bur, and the single site preparation drill. A controlled-torque surgical handpiece is recommended to prepare this site. The implant is placed and then left to osseointegrate for 6-12 weeks
Following treatment, removal is accomplished with an implant trephine
How are palatal implants removed?
An implant trephine
The surgical process of placing most TADs is less invasive than placing implants. Many placement procedures can be completed with ___. When is local anesthesia needed?
A strong topical anesthetic
When the mucosa is thick or highly keratinized
True or false.. each individual TAD system has its own drill set
True
Various systems call for a tissue puncture if the location is planned on the unattached mucosa.
True or false… most TAD systems are drill-free
True
However when dealing with highly dense bone, a pilot drill that usually is 0.2mm smaller than the diameter of the TAD can be utilized
How are TADs removed? How is this possible?
Without any topical or local anesthesia
Reversing the driver
This is possible because TADs do not integrate as completely as dental implants, making removal less of a problem. (If the TAD does integrate, the risk of fracture is present, especially with smaller diameter implants.
What is the minimum recommended diameter for TADs?
The commonly available 1.6mm
Breakage with this size is rare, but if breakage happens, a trephine is necessary to fully remove the TAD
Surgical procedures for orthodontic plates almost exclusively require a ___.
Most of the screws for plates [do/do not] need pilot drills for placement
Soft tissue flap.
Do not
Before placement of a TAD, the mucosa is cleaned with ____, then ___ is usually adequate to anesthetize the soft tissue because a profound anesthesia of the bone or PDL is not recommended.
Chlorhexidine
Topical anesthesia
After topical anesthesia, a periodontal probe is used to measure ____.
The selected appropriate length should allow the thickest diameter of the conical TAD to reside in the ___
The mucosal thickness which can help determine the appropriate length of the TADs at the intended placement site.
Cortical bone
When a ___ is bein placed, the insertion is done directly through the mucosa.
Self-drilling
With the insertion of a ____ TAD, a purchase point and a perforation of the cortical bone are accomplished with a low speed contra-angle handpiece under saline solution irrigation followed by TAD installation
Self-tapping
The TAD is then inserted manually with its driver or a hand-driver with a ___
Torque gauge
Following insertion of the TAD, the head of the TAD remains outside of the mucosa, with the base of the head or the collar resting against the __ creating a gentle ___
Mucosa
Seal
What is the procedure if the TAD is to be placed in the unattached mucosa?
A tissue punch that closely proximates the TAD’s diameter is needed to prevent soft-tissue bunching around the drill or the TAD, which results in postinsertion pain and inflammation later.
Describe the protocol for palatal implant applications.
The palatal mucosa is perforated to the cortical bone using a mucosal punch and removed with an elevator or curette. After smoothing the exposed bone surface to prevent the profile drill from slipping, the center of the implant site is marked with a round bur. The implant bed is then prepared to the required width and depth using a series of pilot and twist drills. The drill axis perpendicular to the bone surface is defined based on the pre-surgical analysis from the radiographic images. While the insertion site is prepared, intermediate drilling and cooling of the channel with pre-cooled physiologcal saline should be carried along. The implant is then hand-installed as far into the site as possible and followed by use of a ratchet to tighten the implant to its final position
The implant is covered with a healing cap to prevent the inner screw well from clogging or vcovered by hyperplastic mutual tissue. It should be left undisturbed for 12 weeks before loading.
How long do palatal implants need to integrate before loading?
12 weeks
The placement of an implant in orthodontic treatment as an absolute anchorage devices facilitiates mechanotherapy. The inactive waiting time of at least __ months following insertion should not be seen as a delay in treatment because the advantages outweigh this delay. However, the general consensus on the timing for loading of TADs is that ___ is successful using forces ranging from 150-500g.
3
Immediate loading!!!
Although some still wait for healing of the peri-TAD tissues, increased failure rates due to immediate loading have not been recently reported
For direct anchorage, the line of action of the force has to pass through the mini screw. If the line of action of the force does not pass through the mini-screw, as would be the case with a power arm, what could happen?
A force away from the mini-screw long axis would be generated. Since the miniscrews are not osseointegrated, a shearing force of this sort would likely lead to screw loosening and failure
As a general rule, for dental restorative implants, at least ___mm of bone should be present circumferentially around the implant
1mm
True or false… dental restorative implants placed prior to the completion of orthodontic treatment is not recommended. Why?
True, it is not recommended because it may interfere with the final alignment of the dentition, the restorability of the implant, and possibly the survival of the implant.
Dental implants placed in the retromolar area can assist in what tooth movements?
Retraction/distalization
Intrusion
Leveling of the arches
True or false.. the palate is a fine location with sound bone and minimal limiting anatomy
True
The force vectors with palatal implants can be easily adjusted during treatment, which makes them suitable in correcting __, ___, ___, and ___.
A single palatal implant can be used for what type of motions?
Openbites
Class 2
Class 3
Debilated dentitions
Intrusion
Retraction
Midline rotations
True or false… a single palatal implant can be used for intrusion, retraction, or midline rotations, where numerous mini-implants may be required
True
TADs can help __, ___, ___, and ___ single teeth or entire segments of teeth
Retract
Protrude
Intrude
Extrude
True or false… TADs are not capable of resisting forces in different directions once they are placed
True
Unfortunately, often the failure of a TAD in a strategic site may stall treatment until the bone has healed enough to place another. Or may result in major changes in treatment plan
Define osseointegration in orthodontics
A process whereby a clinically asympotmaic, rigid fixation of alloplastic material is achieved and maintained in bone during functional loading.
The percentage of implant-to-bone contact in removed implants have reported an average of ___% with a range from __-__%, shoring comparable results as osseointegrated prosthetic endosseous implants that yield at least 60% bone to implant contact.
75%
34%-93%
The concept of primary stability has greater importance in TADs than restorative implants because TADs…
Do not have the potential to become stabler overtime due to their polished surfaces.
In an animal study, mini-screw TADs showed as little as __% bone contact at the bone-implant interface successfully resisted orthodontic force.
5%
Integration of the TAD threads with the ___ is the main anchor of the TAD bone interface
Cortical bone
Why should placement torques of TADs be used with caution?
They may result in excessive stress on the insertion hole (cortical bone is where most stability comes from)
What is the success rate of palatal implants?
95.7%
What is the success rate of TADs?
90%
Question
18
Page 258
It has been estimated that growth in the maxillary width is an average of __mm between ages 10 and 18
3mm
Why should palatal implants not be placed at the midline in growing patients?
The restricting effect of the implants on the transverse growth of the maxilla has been presented in animal studies
Also, placement of implants in the midpalatal suture in growing patients should not be recommended because of the questionable quality of bone in that area
*instead, paramedian placement should be considered
True or false… by implant placement in the palate, the sutureal lowering of the maxillary complex as well as the apposition at the orbital floor and at the infrazygomatic crest should not be affected; however, the resorptive lowering of the nasal floor and the increase of the alveolar bone height of the maxilla can be influenced
True
Between age 4 and adulthood, the nasal floor drifts ___mm inferiorly and the height of the maxillary alveolar bone increases ___mm. Assuming that about 1/3rd of these growth changes takes place from age 12 - adulthood, that implies a residual vertical growth of about ___in the palate and about ___ in the alveolar bone both by drift.
- 6mm
- 6mm
- 5mm
5mm
Osseointegrated implants are in direct contact with bone, do not possess a PDL, and behave like ___. Therefore, a palatal implant would remain an average ___mm behind its surrounding bone whereas an implant placed in the alveolar bone would produce an infraocclusion of ___ during the same period.
Ankylosed teeth
1.5mm
5mm
Because palatal implants may be submerged in bone (like ankylosed teeth) what is an important thing to consider if it is attached to teeth directly or indirectly?
It may lead to infraeruption of a single tooth, several teeth, or the whole maxillary dentition
One should keep in mind that palatal implants, and TADs, remain in situ for ___ years. Thus, potential ___ impairment is likely to be limited to values less than __mm
1-2 years
1mm
Name 4 complication classifications that can occur with TADs
1) during insertion (periodontal damage to root surface, damage to important anatomy, slippage, breakage)
2) during loading (loosening and migration of the TAD)
3) soft tissue complications during treatment (ulcers, soft tissue coverage, inflammation, peri-implantitis)
4) during removal (fracture of TADs due to partial osseointegration)
What is the most likely complication with TADs?
Damage of the root surface and PDL
How are palatal implants removed? How long does recover take?
With a trephine that separates the bone from the devices.
After, the clinician should check for possible oral-nasal communication
Full recovery at the original anchorage site may be observed 3-4 weeks after removal
How are TADs removed?
Usually with NO numbing agent. Simply, the screwdriver is used to unscrew the mini-screw.
In some cases, the TADs may present partial osseointegration, which may complicate the removal. If it happens, a trephine can be utilized similar to that of the implants.
No soft tissue closure is necessary
True or false.. after TADs are removed, the holes must be covered with soft tissue.
False.
