Orthotown April 2020 - 58

T H E SECO N D L AW O F R E T E N T IO N
IS ABOUT PL ACING THE PRINCIPLES
OF SCIENCE ABOVE THOSE OF
S A L E S M A N S H I P.

2

3
Belts and suspenders

Extract for the space
Self-ligating enthusiasts like to
proclaim that they only "extract for the
face, and not for the space," but this is
a fallacy. Refusal to extract premolars
when necessary will result in dental
protrusion, second-molar impaction,
bite opening (with potential condylar
resorption), lip incompetency and
greater relapse. In actuality, you might
have to extract for the space and accept
the face-for example, when you're
presented with a maxillary-deficient
patient with impacted canines or a
hyperdivergent retrognathic patient
with mandibular crowding.
The second law of retention is
about placing the principles of science
above those of salesmanship. There is
no magic bracket that can grow bone.
Expansion studies have shown that
approximately 5 millimeters of arch
perimeter can be gained with stability
from treatment. Therefore, according
to Dr. James A. McNamara, 3-6mm
of mandibular crowding is a borderline
extraction case, and 6mm or more is
clear-cut. An orthodontist who refuses
to extract premolars places a lot of faith
in the durability of bonded retainers.

58

Multistranded bonded retainers
have a relatively high failure rate.
Approximately 20% of mandibularand 50% of maxillary-bonded retainers
fail within five years. Furthermore,
a longer-span retainer has a higher
incidence of failure. This is particularly
true for maxillary retainers that extend
to the canines and mandibular retainers
that extend to the premolars. If you
choose to place bonded retainers, they
should be accompanied by removable
overlays-the orthodontic equivalent
of wearing both a belt and suspenders.
The third law of retention is about
understanding the limitations of
bonded retainers. Even if the retainer
does not fail, relapse can still occur
in the absence of a removable overlay.
For example, spacing can appear if the
bonded retainer stretches, unwanted
torque can be expressed on the teeth
that are bonded to the wire, and
anterior teeth can extrude en masse,
causing the overbite to return. Always
remember that bonded retainers serve
as backup to removable retainers rather
than as their replacement.

APRIL 2020 // orthotown.com

OT0420_KravitzRetention_AG_V3.indd 58

3/26/20 1:08 PM



http://www.orthotown.com

Orthotown April 2020

Table of Contents for the Digital Edition of Orthotown April 2020

Orthotown April 2020 - Intro
Orthotown April 2020 - Cover1
Orthotown April 2020 - Cover2
Orthotown April 2020 - 1
Orthotown April 2020 - 2
Orthotown April 2020 - 3
Orthotown April 2020 - 4
Orthotown April 2020 - 5
Orthotown April 2020 - 6
Orthotown April 2020 - 7
Orthotown April 2020 - 8
Orthotown April 2020 - 9
Orthotown April 2020 - 10
Orthotown April 2020 - 11
Orthotown April 2020 - 12
Orthotown April 2020 - 13
Orthotown April 2020 - 14
Orthotown April 2020 - 15
Orthotown April 2020 - 16
Orthotown April 2020 - 17
Orthotown April 2020 - 18
Orthotown April 2020 - 19
Orthotown April 2020 - 20
Orthotown April 2020 - 21
Orthotown April 2020 - 22
Orthotown April 2020 - 23
Orthotown April 2020 - 24
Orthotown April 2020 - 25
Orthotown April 2020 - 26
Orthotown April 2020 - 27
Orthotown April 2020 - 28
Orthotown April 2020 - 29
Orthotown April 2020 - 30
Orthotown April 2020 - 31
Orthotown April 2020 - 32
Orthotown April 2020 - 33
Orthotown April 2020 - 34
Orthotown April 2020 - 35
Orthotown April 2020 - 36
Orthotown April 2020 - 37
Orthotown April 2020 - 38
Orthotown April 2020 - 39
Orthotown April 2020 - 40
Orthotown April 2020 - 41
Orthotown April 2020 - 42
Orthotown April 2020 - 43
Orthotown April 2020 - 44
Orthotown April 2020 - 45
Orthotown April 2020 - 46
Orthotown April 2020 - 47
Orthotown April 2020 - 48
Orthotown April 2020 - 49
Orthotown April 2020 - 50
Orthotown April 2020 - 51
Orthotown April 2020 - 52
Orthotown April 2020 - 53
Orthotown April 2020 - 54
Orthotown April 2020 - 55
Orthotown April 2020 - 56
Orthotown April 2020 - 57
Orthotown April 2020 - 58
Orthotown April 2020 - 59
Orthotown April 2020 - 60
Orthotown April 2020 - 61
Orthotown April 2020 - 62
Orthotown April 2020 - 63
Orthotown April 2020 - 64
Orthotown April 2020 - 65
Orthotown April 2020 - 66
Orthotown April 2020 - 67
Orthotown April 2020 - 68
Orthotown April 2020 - 69
Orthotown April 2020 - 70
Orthotown April 2020 - 71
Orthotown April 2020 - 72
Orthotown April 2020 - Cover3
Orthotown April 2020 - Cover4
https://www.nxtbook.com/farran/orthotown/orthotown-april-2024
https://www.nxtbook.com/farran/orthotown/orthotown-march-24
https://www.nxtbook.com/farran/orthotown/orthotown-january-february-2024
https://www.nxtbook.com/farran/orthotown/orthotown-december-2023
https://www.nxtbook.com/farran/orthotown/orthotown-november-2023
https://www.nxtbook.com/farran/orthotown/orthotown-october-2023
https://www.nxtbook.com/farran/orthotown/orthotown-september-2023
https://www.nxtbook.com/farran/orthotown/orthotown-july-august-2023
https://www.nxtbook.com/farran/orthotown/orthotown-june-2023
https://www.nxtbook.com/farran/orthotown/orthotown-may-2023
https://www.nxtbook.com/farran/orthotown/orthotown-april-2023
https://www.nxtbook.com/farran/orthotown/orthotown-march-2023
https://www.nxtbook.com/farran/orthotown/orthotown-january-february-2023
https://www.nxtbook.com/farran/orthotown/orthotown-december-2022
https://www.nxtbook.com/farran/orthotown/orthotown-november-2022
https://www.nxtbook.com/farran/orthotown/orthotown-october-2022
https://www.nxtbook.com/farran/orthotown/orthotown-september-2022
https://www.nxtbook.com/farran/orthotown/orthotown-july-august-2022
https://www.nxtbook.com/farran/orthotown/orthotown-june-2022
https://www.nxtbook.com/farran/orthotown/orthotown-may-2022
https://www.nxtbook.com/farran/orthotown/orthotown-april-2022
https://www.nxtbook.com/farran/orthotown/orthotown-march-2022
https://www.nxtbook.com/farran/orthotown/orthotown-january-february-2022
https://www.nxtbook.com/farran/orthotown/orthotown-december-2021
https://www.nxtbook.com/farran/orthotown/orthotown-november-2021
https://www.nxtbook.com/farran/orthotown/orthotown-october-2021
https://www.nxtbook.com/farran/orthotown/orthotown-september-2021
https://www.nxtbook.com/farran/orthotown/orthotown-july-august-2021
https://www.nxtbook.com/farran/orthotown/orthotown-june-2021
https://www.nxtbook.com/farran/orthotown/orthotown-april-2021
https://www.nxtbook.com/farran/orthotown/orthotown-march-2021
https://www.nxtbook.com/farran/orthotown/2021JanuaryFebruary
https://www.nxtbook.com/farran/orthotown/December2020
https://www.nxtbook.com/farran/orthotown/2020November
https://www.nxtbook.com/farran/orthotown/2020October
https://www.nxtbook.com/farran/orthotown/2020September
https://www.nxtbook.com/farran/orthotown/2020JulyAugust
https://www.nxtbook.com/farran/orthotown/2020June
https://www.nxtbook.com/farran/orthotown/2020May
https://www.nxtbook.com/farran/orthotown/2020April
https://www.nxtbook.com/farran/orthotown/2020March
https://www.nxtbook.com/farran/orthotown/2020JanuaryFebruary
https://www.nxtbook.com/farran/orthotown/2019December
https://www.nxtbook.com/farran/orthotown/2019November
https://www.nxtbook.com/farran/orthotown/2019October
https://www.nxtbook.com/farran/orthotown/2019September
https://www.nxtbook.com/farran/orthotown/2019JulyAugust
https://www.nxtbook.com/farran/orthotown/2019June
https://www.nxtbook.com/farran/orthotown/2019May
https://www.nxtbook.com/farran/orthotown/2019April
https://www.nxtbook.com/farran/orthotown/2019March
https://www.nxtbook.com/farran/orthotown/2019JanFeb
https://www.nxtbook.com/farran/orthotown/2018December
https://www.nxtbook.com/farran/orthotown/2018November
https://www.nxtbook.com/farran/orthotown/2018October
https://www.nxtbook.com/farran/orthotown/2018September
https://www.nxtbook.com/farran/orthotown/2018August
https://www.nxtbook.com/farran/orthotown/2018June
https://www.nxtbook.com/farran/orthotown/2018May
https://www.nxtbook.com/farran/orthotown/2018April
https://www.nxtbook.com/farran/orthotown/2018March
https://www.nxtbook.com/farran/orthotown/2018February
https://www.nxtbook.com/farran/orthotown/2017December
https://www.nxtbook.com/farran/orthotown/2017November
https://www.nxtbook.com/farran/orthotown/2017October
https://www.nxtbook.com/farran/orthotown/2017September
https://www.nxtbook.com/farran/orthotown/August_2017
https://www.nxtbook.com/farran/orthotown/2017June
https://www.nxtbook.com/farran/orthotown/2017May
https://www.nxtbook.com/farran/orthotown/2017April
https://www.nxtbook.com/farran/orthotown/March2017
https://www.nxtbook.com/farran/orthotown/2017JanFeb
https://www.nxtbook.com/farran/orthotown/2016_December_Orthotown
https://www.nxtbook.com/farran/orthotown/2016November
https://www.nxtbook.com/farran/orthotown/2016October
https://www.nxtbook.com/farran/orthotown/2016september
https://www.nxtbook.com/farran/orthotown/2016august
https://www.nxtbook.com/farran/orthotown/2016june
https://www.nxtbook.com/farran/orthotown/2016may
https://www.nxtbook.com/farran/orthotown/2016april
https://www.nxtbook.com/farran/orthotown/2016march
https://www.nxtbook.com/farran/orthotown/2016february
https://www.nxtbook.com/farran/orthotown/2015december
https://www.nxtbook.com/farran/orthotown/2015november
https://www.nxtbook.com/farran/orthotown/2015october
https://www.nxtbook.com/farran/orthotown/2015september
https://www.nxtbook.com/farran/orthotown/2015august
https://www.nxtbook.com/farran/orthotown/2015june
https://www.nxtbook.com/farran/orthotown/2015may
https://www.nxtbook.com/farran/orthotown/2015april
https://www.nxtbook.com/farran/orthotown/2015march
https://www.nxtbook.com/farran/orthotown/2015february
https://www.nxtbook.com/farran/orthotown/2014december
https://www.nxtbook.com/farran/orthotown/2014november
https://www.nxtbook.com/farran/orthotown/2014october
https://www.nxtbook.com/farran/orthotown/2014september
https://www.nxtbook.com/farran/orthotown/2014august
https://www.nxtbook.com/farran/orthotown/2014june
https://www.nxtbook.com/farran/orthotown/2014may
https://www.nxtbook.com/farran/orthotown/2014april
https://www.nxtbook.com/farran/orthotown/march2014
https://www.nxtbook.com/farran/orthotown/2014february
https://www.nxtbook.com/farran/orthotown/2013december
https://www.nxtbook.com/farran/orthotown/2013november
https://www.nxtbook.com/farran/orthotown/2013october
https://www.nxtbook.com/farran/orthotown/2013september
https://www.nxtbook.com/farran/orthotown/2013august
https://www.nxtbook.com/farran/orthotown/2013june
https://www.nxtbook.com/farran/orthotown/2013may
https://www.nxtbook.com/farran/orthotown/2013april
https://www.nxtbook.com/farran/orthotown/2013march
https://www.nxtbook.com/farran/orthotown/2013janfeb
https://www.nxtbook.com/farran/orthotown/2012december
https://www.nxtbook.com/farran/orthotown/2012november
https://www.nxtbook.com/farran/orthotown/2012october
https://www.nxtbookmedia.com