what are the two major causes of orthodontic relapse?
continued growth and tissue rebound
changes resulting from continued growth in a class II, class III, deep bite, or open bite pattern contribute to ___
- a return of the original malocclusion
- these changes are due to the pattern of skeletal growth, not just tooth movement
controlling relapse that restults from continued growth requires continuation of active treatment after the fixed appliance has been removed. what is this type of control referred to as?
active retention
active retention takes one of two forms. what are they?
- continuation of extra oral forces in conjunction with retainers (head gear)
- use of a functional appliance instead of retainers
what type of periodontal fibers are responsible for tissue rebound that causes relapse?
- transseptal fibers
- extend inter-proximally over the alveolar bone and are embedded in the cementum of adjacent teeth
- they form an interdental ligament and keep all the teeth in contact
- these fibers may be considered as belonging to the gingiva because they don’t have an osseous attachment
a major reason for retention is to hold the teeth until ___ remodeling can take place
soft tissue
T or F:
even with the best tissue remodeling, some rebound from the application of orthodontic forces occurs
true
what are two ways that rebound can be prevented?
- overtreatment, so that any rebound will only bring the teeth back to their proper position
- adjunctive periodontal surgery to reduce rebound from elastic fibers in the gingiva
a class II or class III malocclusion should be overtreated by ___mm to accommodate the expected relapse
1-2mm
a crossbite correction should be overtreated by ___mm to accommodate the expected relapse
1-2mm
how should irregular and rotated teeth be overtreated to accommodate for expected relapse?
they should be held in a slightly overcorrected position (either by activating wings or rotation wedges) for a few months but should not be incorporated into finishing wires
what are the 3 most popular retainers?
- hawley with labial bow or wrap design
- essix clear retainers
- bonded permanent retainers
describe hawley retainers
- uses the palate as skeletal anchorage to prevent tooth movement
- can have a finger spring to move a tooth - only tipping movement
two types of bone can be identified according to the pattern of ___. what are the two types?
- pattern of collagen forming the osteoid
- woven bone and lamellar bone
which type of bone is characterized by a haphazard organization of collagen fibers and is mechanically weak?
woven bone
what type of bone is characterized by a regular parallel alignment of collagen into sheets (lamellae) and is mechanically strong?
lamellar bone
after a tooth has been moved from one position to another, the resulting bone is called ___
transitional bone
it typically takes ___ weeks for woven bone to mature to lamellar bone, creating a ___ month window which is typically used for full time retainer wear after ortho treatment
- 12 weeks
- 3 month
what is the rationale for retention with either fixed or removable retainers (3 things)?
- allow time for reorganization
- minimize changes due to growth
- retainer wear part time until growth is complete
- maintain teeth in unstable positions
- sometimes need to compromize treatment
- patients typically require some form of retention for life, which is typically a permanent retainer
significant reogranization of the PDL occurs in the first ___ months after removal of fixed appliances, so full time retention is critical during this time. part time retention is recommended for how long after?
- 3 months
- a year or longer
the ___ procedure consists of inserting the sharp point of a fine blade into the gingival sulcus down to the crest of the alveolar bone. cuts are made interproximally on each side of the rotated tooth and along the labial and lingual gingival margins, unles the labial or lingual margins are thin.
circumferential supracrestal fibrotomy (CSF)
do patients typically experience discomfort after the CSF procedure? does it require a periodontal pack?
no periodontal pack is necessary and there is only minor discomfort after the procedure
what is the CSF procedure used for?
helps with orthodontic retention
and is an alternative method to CSF? what does this modification do?
- make an incision int he center of each gingival papilla 1-2mm below the height of bone bucally and lingually
- this modification is said to reduce the possibility that the height of the gingival attachment will be reduced after the surgery, and is particalarly indicated for esthetically sensitive areas (maxillary incisor region)
