The Black Box of Orthodontic Research

THE BLACK BOX
OF ORTHODONTIC RESEARCH
Second Edition
2021
RAED H. ALRBATA
BDS. JBOrth. OMI Fellow
Royal Medical Services
Amman. Jordan

The Black Box of Orthodontic Research.
ISBN: 978-9957-67-019-1
The Hashemite Kingdom of Jordan
The Deposit Number at the National Library: (2017/6/3017)
©Raed H. Alrbata, 2021
Second Edition
All rights reserved. No part of this publication may be reproduced, stored in a retrieval
system, or transmitted, in any form or by any means, without the prior permission from
the author.
Raed H. Alrbata, Senior Specialist in Orthodontics, Royal Medical Services, Department
of Orthodontics.
E-mail: raedrbata@yahoo.com
Amman, Jordan

Preface
The black box of orthodontic research is now in its second edition. This book is
considered as a reference for orthodontic professionals who look for validation
and optimization of their basic knowledge, experience and updated research concerning
the orthodontic field.
The continuing development in orthodontic materials and mechanics led researchers
from different countries to employ their efforts and capabilities to investigate any relation
between these and their use in orthodontic treatment. Running multiple studies scenarios
for different populations, needs to be organized and ranked according to article type and
methodology incorporated to simplify the process of referencing and validating each
orthodontic procedure used.
For this, it was my honorable opportunity to give a hand in this issue. For most orthodontic
subjects encountered daily in practice, the most leading results, statements and conclusions
of concern mentioned in literature will be documented in order of publishing time.
Considering theses, beside focusing on the mentioned reference, will give orthodontists
the whole picture of the stroy.
It should be stated here that more focus on the leading orthodontic journals will be
noticed. Any valuable notes for the purpose of improving the way the book is presented
for audience will be of our great appreciation.
Raed H. Alrbata

Table of Contents
Section One
Materials Used In Orthodontics��7
Section Two
Etiology of Malocclusion ��23
Section Three
Treatment Planning��33
Section Four
Early Orthodontic Treatment��59
Section Five
Anchorage in Orthodontics��67
Section Six
Orthodontic Malocclusions and Other Problems��87
Section Seven
Orthodontic Appliances��121
Section Eight
Orthodontic Biomechanics and Procedures��157
Section Nine
Orthodontics and Orthognathic Surgery��181
Section Ten
Retention and Stability ��195
Section Eleven
Complications of Orthodontic Treatment ��213
Section Twelve
Cleft Lip and Palate��241
Section Thirteen
Pioneers in Orthodontics��249

Journals Abbreviations
Acta Odontologica Scandinavica: AOS
Andrews Journal: AJ
Australian Orthodontic Journal: AOJ
British Dental Journal: BDJ
British Journal of Orthodontics: BJO
Clinical Oral Implantology Research: COIR
Cleft Palate and Craniofacial Journal: CPCJ
Dental Record Journal: DRJ
Dentomaxillofacial Radiology: DR
International Journal of Adult Orthodontics and Orthognathic Surgery: IJAOOS
International Journal of Oral Maxillofacial Implants: IJOMI
International Journal of Paediatric Dentistry: IJPD
International Journal of Prosthodontics: IJP
Journal of the American Dental Association: JADA
Journal of Canadian Dental Association: JCDA
Journal of Clinical Orthodontics: JCO
Journal of Clinical Paediatric Dentistry: JCPD
Journal of Craniofacial Surgery: JCS
Journal of Dental Research: JDR
Journal of Esthetic Dentistry: JED
Journal of Oral Rehabilitation: JOR
Journal of Oral and Maxillofacial Surgery: JOMS
Journal of Orofacial Orthopaedics: JOO
Journal of Orthodontics: JO
Journal of Periodontology: JP
Journal of Plastic and Reconstructive Surgery: JPRS
Journal of Prosthetic Dentistry: JPD
Journal of the American Dental Association: JADA
Journal of the Korean Academy of Prosthodontics: JKAP
Journal of Wonkwang Dental Research Institute: JWDRI
Open Dental Journal: ODJ
Plastic and Reconstructive Surgery Journal: PRSJ
Puerto Rico Health Sciences Journal: PRHSJ
Quintessence International: QI
Scandinavian Journal of Dental Research: SJDR
World Journal of Orthodontics: WJO

7
7
Section One
Materials Used In Orthodontics
Etching and Bonding Materials
Self-etching Primers (SEPs)
Light Curing Devices
Orthodontic Brackets
Self-ligating Brackets
Archwires Used in Orthodontics

9
9
The main materials and equipments used in the daily orthodontic practice will be available
in this section. Etching and bonding materials, brackets, archwires and light curing devices
will be investigated for their performance, effectiveness, durability and safety.
Etching and Bonding Materials
The mean linear tensile bond strength of enamel is 14.5 MPa.
Bowen and Rodriguez (1962). Tensile strength and modulus of elasticity of tooth structure
and several restorative materials. JADA64: 378
Fractures in enamel can occur with bond strengths as low as 13.5 MPa.
Retief DH (1974). Failure at the dental adhesive-etched enamel interface. JOR 1: 265-284
The minimum bond strength needed for clinical use is 5.9 - 7.8 MPa.
Reynolds IR (1975). A review of direct bonding. BJO 2: 171-178
No significant difference in bond strength between etching for 15, 30, 60 and 90
seconds; etching for longer than 90 seconds may result in lower bond strengths.
Wang and Lu (1991). Bond strength with various etching times on young permanent
teeth. AJODO 100: 72-79
The conventional resin primer system produce higher bond strength (10.4 MPa)
compared to glass ionomer cement (6.5 MPa).
Bishara et al (1999). Shear bond strength of composite, glass ionomer and acidic primer
adhesive systems. AJODO 115: 24-28
Polyacrylic acid produces slight etching of the enamel surface. Calcium sulphate
dihydrate crystals are formed which bond securely to the enamel surface. These can
provide a shear bond strength above the threshold of 6-8 MPa recommended by
Reynolds but 30% lower than that achieved with phosphoric acid.
Bishara et al (2000). Effect of altering the type of enamel conditioner on the shear bond
strength of a resin-reinforced glass ionomer adhesive. AJODO118: 288-294

Section
One
10
The most widely accepted choice for routine orthodontic bonding is the use of 37%
phosphoric acid with a 30 seconds etch time.
Gardner and Hobson (2001). Variations in acid-etch patterns with different acids and
etch times. AJODO 120: 64-67
No advantage or disadvantage of precuring the primer on the bonding strength.
Osterle et al (2004). Effect of primer precuring on the shear bond strength of orthodontic
brackets. AJODO 126: 699-702
The addition of chlorhexidine digluconate to conventional GICs does not negatively
modify the mechanical properties and may increase the antibacterial effects around
the GICs even for relatively long periods of time.
Farret et al (2011). Can we add chlorhexidine into glass ionomer cements (GICs) for band
cementation?Angle Orthod 81: 496-502
Light-cured composite resin was compared with chemical-cured composite resin:
The polymerization mode did not influence the bracket survival rate significantly.
Mohammed et al (2016). Comparing orthodontic bond failures of light-cured composite
resin with chemical-cured composite resin: A 12-month clinical trial. AJODO 150: 290–
294
A multicenter, single-blind, RCT, Light-cured resin-modified glass ionomer cement (RM-
GIC) vs light-cured composite for bonding orthodontic brackets:
Evidence that bonding with RM-GIC decreases demineralization was not found.
There might be other reasons for using RM-GIC, such as a shorter cleanup time.
Benson et al (2019). Resin-modified glass ionomer cement vs composite for orthodontic
bonding: A multicenter, single-blind, randomized controlled trial. AJODO 155:10-18

11
Self-etching Primers (SEPs)
Self-etchingprimersaremoistureinsensitiveandworkinwetandsalivacontaminated
conditionswhilstmaintainingtheirinitialbondstrengthlongterm.
Cinader (2001). Chemical processes and performance comparisons of Trans bond Plus
self-etching primer . Ortho Persp (8): 5-6
The use of the SEP produced a significantly lower but clinically acceptable bond
strength (7.1 MPa) than Transbond XT (10.4 MPa).
Bishara et al (2001). Effect of a self-etch primer/adhesive on the shear bond strength of
orthodontic brackets. AJODO 119: 621-624
Weak evidence that the self-etching primer has a higher failure rate but is still well
within the limits of clinical acceptability.
Ireland et al (2003). An in vivo investigation into bond failure rates with a new self-
etching primer system. AJODO 124: 323-326
The use of SEP is quicker than a conventional bonding technique. No difference in
survival time between the two bonding systems.
Aljubouri et al (2003). Laboratory evaluation of a self-etching primer for orthodontic
bonding. EJO 25: 411-415
The bond strengths for the self-etching primer and Transbond XT and 35%
phosphoric acid and Enlight were compared and found similar.
Grubisa et al (2004).An evaluation and comparison of orthodontic bracket bond strengths
achieved with self-etching primer.AJODO 126: 213-219
Pumicing was found to produce a statistically and clinically significant reduction in
clinical bond failure rates when using SEPs.
Burgess et al (2006). Self-etching primers: is prophylactic pumicing necessary? A
randomized clinical trial. Angle Orthod 76: 114–118

Section
One
12
The shear bond strength of flowable composites increases with filler content.
However, they have lower shear bond strength than 3M Unitek Transbond XT.
Uysal et al (2008). Microleakage under metallic and ceramic brackets bonded with
orthodontic self-etching primer systems. Angle Orthod 78: 1089–1094
The effect of moisture contamination before and after the application of Transbond
Plus self-etching primer with uncontaminated bonding was investigated. The
observation period was a minimum of six months. The overall bond failure rate
was 6.08% and there were no significant differences between the contaminated and
uncontaminated bondings.
Campoy et al (2010). Effect of saliva contamination on bracket failure with a self-etching
primer: A prospective controlled clinical trial. AJODO 137: 679-683
Orthodontic Brackets
Andrews described different incisor bracket sets to be used for different skeletal patterns.
The amount of torque in the brackets was the only difference.
Set A brackets: designed for Class 2 skeletal patterns had less palatal root torque in
the upper incisors and more labial crown torque in the lower incisors.
Set C for Class 3 skeletal patterns had the reverse.
Set S for Class 1 malocclusions.
Translation brackets: to compensate for the unwanted tooth movements that occurred
during closure of extraction spaces. Had increased tip and antirotation.
Andrews LF (1989). Straight Wire The Concept and the Appliance San Diego, L A Wells
Co.
Gingival offset brackets have a risk of bond failure which is five times less than with
conventionalbrackets.
Tidy and Coley-Smith (1998). Gingival offset premolar brackets - a randomised clinical
trial Paper presented at the Golden Jubilee Symposium at the RCSEd.

13
The relationship between bond strength and pad size with both microetched and
conventional bases was investigated:
There was no difference in shear bond strength for pads between 6.82 mm2 and
12.35 mm2 in size. No difference in shear bond strength between a manufacturer-
applied microetching process (grit blasting) and sandblasting in the surgery with a
Danville Engineering sandblaster.
MacColl et al (1998). The relationship between bond strength and orthodontic bracket
base surface area with conventional and microetched foil-bases. AJODO 113: 276-281
Minor pitting and corrosion can be seen on titanium brackets exposed to acidic
fluoridecontainingtoothpastesbutthisisnotlikelytoaffecttheirclinicalperformance
during the average orthodontic treatment time.
Harzer et al (2001). Sensitivity of titanium brackets to the corrosive influence of fluoride-
containing toothpaste and tea. Angle Orthod 71: 318-323
Bracket prescription had no effect on the aesthetic judgments made by experienced
orthodontists from the post-treatment study models of patients treated with premolar
extractions and a fixed appliance system using either a Roth or a MBT prescription.
Moesi et al (2013). Roth versus MBT: does bracket prescription have an effect on the
subjective outcome of pre-adjusted edgewise treatment? EJO 35: 236-243
Maxillary first molar anchorage loss between 0.018-inch and 0.022-inch slot fixed
appliance systems:
Bracket slot size has no significant influence on the maxillary molar anchorage loss
during orthodontic treatment.
Yassir et at (2019). Does anchorage loss differ with 0.018-inch and 0.022-inch slot bracket
systems?Angle Orthod 89(4):605–610

Section
One
14
Treatment duration of 0.018-inch and 0.022-inch slot systems and factors of influence:
No statistically or clinically significant difference in treatment duration between
0.018-inch and 0.022-inch slot bracket systems. Increasing patient age, Class II
division 2 malocclusion, number of failed and emergency appointments, and multi-
operator treatment all increase orthodontic treatment duration.
Yassir et al (2019). A randomized clinical trial of the effectiveness of 0.018-inch and
0.022-inch slot orthodontic bracket systems: part 1, duration of treatment. EJO 41:133–142
Quality of orthodontic treatment between 0.018-inch and 0.022-inch slot bracket systems:
No statistically or clinically significant differences in the quality of occlusal
outcomes, incisor inclination and patient perception of treatment between 0.018-
inch and 0.022-inch slot bracket systems.
Yassir et al (2019). A randomized clinical trial of the effectiveness of 0.018-inch and
0.022-inch slot orthodontic bracket systems: part 2-quality of treatment. EJO 41:143–153
Comparison of orthodontically induced inflammatory root resorption (OIIRR) and patient
perception of pain during orthodontic treatment between 0.018-inch and 0.022-inch slot
bracket systems:
The effect of bracket slot size on the severity of OIIRR and patient perception of
pain are not significant.
El-Angbawi et al (2019).Arandomized clinical trial of the effectiveness of 0.018-inch and
0.022-inch slot orthodontic bracket systems: part 3-biological side-effects of treatment.
EJO 41:154–164
Self-ligating Brackets (SLBs)
When initially placed, an elastomeric in a figure of 8 configuration increases the
friction by a further 70-220% compared to the “O” configuration.
Sims et al (1993). A comparison of the forces required to produce tooth movement in
vitro using two self-ligating brackets and a pre-adjusted bracket employing two types of
ligation. EJO: 15: 377-385

15
Elastomerics and wire ligatures with respect to various measures of plaque quality and
quantity, gingival index, probing depth and bleeding on probing were compared:
The bacteriology results slightly favoured wire ligation, but not to a significant
extent, but the important sign of bleeding on probing was substantially higher with
elastomeric ligation.
Turkkahraman et al (2005). Archwire ligation techniques, microbial colonization, and
periodontal status in orthodontically treated cases. Angle Orthod 75: 231-236
Very little difference between cases treated with conventional and self-ligation in
terms of arch expansion or incisor proclination.
Fleming et al (2009b). Comparison of mandibular arch changes during alignment and
levelling with two preadjusted edgewise appliances. AJODO 136: 340-347
There is insufficient evidence to support the view that treatment with self-ligating
brackets is more or less efficient than with conventional ligation. Shortened chair
time and slightly less incisor proclination appear to be the only significant advantages
of self-ligating systems over conventional systems that are supported by the current
evidence.
Fleming and Johal (2010). Self-ligating brackets in orthodontics – a systematic review.
Angle Orthod 80:575-584
Chen et al (2010). Systematic review of self-ligating brackets. AJODO 137: 726.e1-726.
e18
Bracket type does not influence the duration of treatment or the number of visits
required.
Fleming et al (2010). Randomized clinical trial of orthodontic treatment efficiency with
self-ligating and conventional fixed orthodontic appliances. AJODO 137: 738–742

Section
One
16
SLBs were no more efficient than conventional brackets in anterior alignment or
passive extraction space closure during the first 20 weeks of treatment.
Ligation technique is only one of many factors that can influence the efficiency of
treatment. Similar changes in arch dimensions occurred, irrespective of bracket type
that might be attributed to the archform of the archwires.
Ong et al (2010). Efficiency of self-ligating vs conventionally ligated brackets during
initial alignment. AJODO 138: 138.e1–138.e7
An alignment-induced increase in the proclination of the mandibular incisors was observed
for 2 groups of SLB and conventional ones:
No difference was identified between both with respect to this parameter. Also, an
increase in intercanine and intermolar widths was noted for both bracket groups; the
self-ligating group showed a higher intermolar width increase than the conventional
group, whereas the amount of crowding andAngle classification were not significant
predictors of post-treatment intermolar width.
Pandis et al (2010). Mandibular dental arch changes associated with treatment of crowding
using self-ligating and conventional brackets. EJO 32: 248-253
Maxillary and mandibular intercanine, interpremolar, and intermolar widths increased
significantly after treatment with the Damon system:
The mandibular incisors were significantly advanced and proclined after treatment
with this system, contradicting the lip bumper theory of Damon. Posttreatment
incisor inclinations did not differ significantly between the Damon group and the
control group. Patients treated with the Damon system completed treatment on
average 2 months faster than patients treated with a conventionally ligated standard
edgewise bracket system.
Vajaria et al (2011). Evaluation of incisor position and dental transverse dimensional
changes using the Damon system. Angle Orthod 81: 647-652

17
The use of conventional or SLBs does not seem to be an important predictor of
mandibular intermolar width in nonextractions patients when the same wire
sequence is used.
Pandis et al (2011). Comparative assessment of conventional and self-ligating appliances
on the effect of mandibular intermolar distance in adolescent nonextraction patients: A
single-center randomized controlled trial. AJODO 140: e99–e105
Self-ligating esthetic brackets do not promote greater or lesser S mutans colonization
when compared with conventional brackets. Differences were found to be related to
the material composition of the bracket.
Nascimento et al (2013). Colonization of Streptococcus mutans on esthetic brackets: Self-
ligating vs conventional.AJODO 143: S72–S77
No difference in the arch dimensional or inclination changes during alignment can
be expected between conventional brackets and either active or passive self-ligation.
Fleming et al (2013). Comparison of maxillary arch dimensional changes with passive and
active self-ligation and conventional brackets in the permanent dentition: A multicenter,
randomized controlled trial. AJODO 144: 185–193
Conventional vs SLBs: Time to initial alignment was significantly shorter for the
conventional bracket than for either the active or passive self-ligating brackets.
There was no statistically significant difference in total space-closure time among
the 3 brackets.
Songra et al (2014). Comparative assessment of alignment efficiency and space closure of
active and passive self-ligating vs conventional appliances in adolescents: A single-center
randomized controlled trial. AJODO 145: 569–578

Section
One
18
No clinically significant difference in treatment efficiency between treatment with a
self-ligating bracket system and a conventional ligation system.
O’Dyweret al (2016). Amulti-center randomized controlled trial to compare a self-ligating
bracket with a conventional bracket in a UK population: Part 1: Treatment efficiency.
Angle Orthod 86: 142-148
No clinically significant difference in pain experience between patients treated with
a self-ligating bracket system compared to those treated with a conventional ligation
system.
Rahman et al (2016). A multicenter randomized controlled trial to compare a self-ligating
bracket with a conventional bracket in a UK population: Part 2: Pain perception. Angle
Orthod 86: 149-156
No differences in maxillary arch dimensional changes or molar and incisor
inclination changes were found in conventional and active and passive SLBs used
with broad archwires.
Atik et al (2016). Evaluation of maxillary arch dimensional and inclination changes with
self-ligating and conventional brackets using broad archwires. AJODO 149: 830–837
Effect of self-ligating brackets (SB) and other related factors that influence orthodontic
treatment time:
SB did not exhibit a significant reduction in treatment time as compared with CB.
Patient cooperation, extractions, and malocclusion severity had a significant impact
on treatment duration.
Jung (2021). Factors influencing treatment efficiency:A prospective cohort study. Angle
Orthod 91(1):1–8.

19
Archwires Used in Orthodontics
The technique of ion implantation is used to modify surfaces exposed to corrosion
or wear.
Mizrahi et al (1991). The effect of Ion implantation on the beaks of orthodontic pliers.
AJODO 99: 513-519
The use of figure of eight ligatures increases the fictional resistance by approximately
one and a half times for most working archwires and by over three times for 0.016”
x 0.022” archwires.
Sims et al (1993). A comparison of the forces required to produce tooth movement in vitro
using two self-ligating brackets and a preadjusted bracket employing two types of ligation.
EJO 15: 377-385
Ideal properties of thermoelastic archwires:
• Highly ductile at room temperature.
• Instantaneous activation at mouth temperature.
• Once fully activated, the wire is not further activated by the heat of the mouth.
• A narrow temperature transition range such that the wire is highly ductile at
room temperature and highly active at mouth temperature.
Bishara et al (1995). Comparisons of thermodynamic properties of three nickel titanium
orthodontic archwires. Angle Orthod 65: 117-122
The amount of torque loss between archwire and bracket is affected by:
• Play between archwire and bracket slot.
• Lack of stiffness of bracket structure or slot.
• Inadequate archwire stiffness.
• Incomplete ligation.
• Manufacturing variability.
Gioka et al (2004). Materials-induced variation in the torque expression of preadjusted
appliances. AJODO 125: 332-338

Section
One
20
The arch form derived from the WALA points is much broader in the premolar and
molar regions. There was significant correlation between the FA and WALA points
particularly in the canine and molar regions and that the WALA points could be used
to indicate basal archform.
Ronay et al (2008). Mandibular arch form: The relationship between dental and basal
anatomy. AJODO 134: 430-438
Two orthodontic archwires (0.016” 35° CuNiTi and 0.016” NiTi) were compared
for effectiveness of resolving mandibular anterior crowding at different rates: the
wire type had no effect on the rate of resolution of anterior mandibular crowding.
Pandis et al (2009). Alleviation of mandibular anterior crowding with copper-nickel-
titanium vs nickel-titanium wires: A double-blind randomized control trial. AJODO 136:
152.e1-152.e7
Most NiTi wires do not exhibit in torsion the superelastic effect traditionally
described in bending and the optimal constant moments necessary to gain third-
order control of tooth movement early in treatment are not present in a preadjusted
edgewise-rectangular NiTi archwire system.
Bolender et al (2010). Torsional superelasticity of NiTi archwires: myth or reality? Angle
Orthod 80: 1100-1109
Despite its antibacterial function, garlic extract increases biofilm formation by S
mutans to orthodontic wire, likely through upregulation of glucosyltransferase
expression. Garlic extract may thus play an important role in increased bacterial
attachment to the wires.
Lee et al (2011). Effect of garlic on bacterial biofilm formation on orthodontic wire. Angle
Orthod 81: 895-900

21
Superelastic NiTi performed significantly better than multistranded (coaxial)
stainless steel wire in the Begg appliance. However, in PEA, there was no significant
difference.
Sandhu et al (2012). Efficiency, behavior, and clinical properties of superelastic NiTi
versus multistranded stainless steel wires. Angle Orthod 82: 915-921
In low-friction mechanics, thermal NiTi wires are to be preferred to superelastic
wires, during the alignment phase due to their lower working forces. In conventional
straight wire mechanics, a low force archwire would be unable to overcome the
resistance to sliding.
Gatto et al (2013). Load–deflection characteristics of superelastic and thermal nickel–
titanium wires. EJO 35: 115-123
The 0.017 × 0.025-inch stainless steel and β-Ti archwires in the 0.018-inch slot
generated higher moments than the 0.019 × 0.025-inch archwires because of lower
torque play. This difference is exaggerated in steel archwires, in comparison with
the β-Ti, because of differences in stiffness.
Sifakakis et al (2014). Torque efficiency of different archwires in 0.018- and 0.022-inch
conventional brackets. Angle Orthod 84: 149-154
ThethreeformsofNiTiwires(0.014-inchsuperelasticNiTi,0.014-inchthermoelastic
NiTi, or 0.014-inch conventional NiTi) were similar in terms of their alignment
efficiency during the initial aligning stage of orthodontic fixed appliance therapy.
Abdelrahman et al (2015). A clinical comparison of three aligning archwires in terms of
alignment efficiency: A prospective clinical trial. Angle Orthod 85: 434-439

23
Section Two
Etiology of Malocclusion
Breastfeeding and Pacifier Use
Mouth Breathing, Obstructive Sleep Apnea (OSA)
Tongue Thrusts
Protecting Teeth Surface
Possible causatives of malocclusions

25
Breastfeeding and Pacifier Use
Children who were breastfed for more than 12 months had a 20-fold lower risk
for the development of posterior crossbite compared with children who were never
breastfed and a 5-fold lower risk compared with those breastfed between 6 and 12
months.
Kobayashi et al (2010). Relationship between breastfeeding duration and prevalence of
posterior crossbite in the deciduous dentition. . AJODO 137; 54–58
The duration of a pacifier habit and short frenulum linguae are associated with
posterior crossbite at the age of 4 or 5 years because of the low tongue posture in
the mouth. Pediatricians and pedodontists should give precise recommendations for
enhancing breast feeding and discontinuing pacifier habits at least until the child is
18 months of age.
Melink et al (2010). Posterior crossbite in the deciduous dentition period, its relation
with sucking habits, irregular orofacial functions, and otolaryngological findings. AJODO
138:32–40
Association between preterm birth and primary-dentition malocclusion and how
breastfeeding and the use of pacifiers are related to this association:
Preterm birth is associated with the development of moderate or severe malocclusion.
Breastfeeding reduces the effect of preterm birth on such malocclusion. Pacifier use
strengthens this association.
Dentists should be aware that preterm birth may be a risk factor for malocclusion in
primary dentition.
The findings reinforce the benefits of breastfeeding on occlusal development and the
negative consequences of pacifier use.
Da Rosa et al (2020). The influence of breastfeeding and pacifier use on the association
between preterm birth and primary-dentition malocclusion: A population-based birth
cohort study. AJODO 157: 754-763

Section
Two
26
Mouth Breathing, Obstructive Sleep Apnea (OSA)
There is no one mandibular advancement device (MAD) design that most effectively
influences perceived treatment efficacy, but efficacy depends on many factors
including materials and method used for fabrication, type of MAD (Monoblock or
Twin-block), and the degree of protrusion (sagittal and vertical).
Ahrensetal(2010).Subjectiveefficacyoforalappliancedesignfeaturesinthemanagement
ofobstructivesleepapnea:Asystematicreview.AJODO138:559–576
The oropharyngeal (OP) airway volumes of Class II patients are smaller when
compared with Class I and Class III patients. Mandibular position with respect to
cranial base affect the OP airway volume.
El H et al (2011). Airway volume for different dentofacial skeletal patterns. AJODO 139:
e511–e521
Nasal obstruction is associated with a decrease in lip-closing force.When the severity
of nasal obstruction reaches a certain level, the lip-closing force is weakened.
Sabashi et al (2011). Nasal obstruction causes a decrease in lip-closing force. Angle
Orthod 81: 750-753
Favorable reductions in sleep variables highlight the potential of microimplant-
based mandibular advancement therapy as an alternative treatment modality for
OSA patients who cannot tolerate continuous positive airway pressure and oral
appliance therapy.
Ngiam and Kyung (2012). Microimplant-based mandibular advancement therapy for the
treatment of snoring and obstructive sleep apnea: a prospective study. Angle Orthod 82:
978-984

27
Patients received adenotonsillectomy have different pattern of arch development
compared with the untreated controls.
After this procedure, the mouth-breathing children showed greater maxillary
transverse development than did the controls. The palatal vault deepened in the
untreated children. The mouth-breathing children in comparison with the nasal-
breathing children have deeper palatal vault, larger mandibular width, and larger
mandibular arch length.
Caixeta et al (2014). Dental arch dimensional changes after adenotonsillectomy in
prepubertal children. AJODO 145: 461–468
Head posture show significant differences in patients with OSA. In general, the
more severe the OSA, the more extended the natural head position as indicated by
increases in the craniocervical angles. The cervical posture parameters may indicate
existing OSA.
Sökücü et al (2016). Relationship between head posture and the severity of obstructive
sleep apnea. AJODO 150: 945–949
Orthodontic treatment in adults does not cause clinically significant changes to the
volume or the minimally constricted area of the upper airway. Dental extractions in
conjunction with orthodontic treatment have a negligible effect on the upper airway
in adults.
Pliska et al (2016). Effect of orthodontic treatment on the upper airway volume in adults.
AJODO 150: 937–944
Tongue Thrusts
Tongue spurs are effective in controlling tongue thrusts and hence closing anterior
open bites.
Huang et al (1990). Stability of anterior openbite treated with crib therapy. Angle Orthod
60: 17-24

Section
Two
28
Simple series of exercises can be taught to patients with a tongue thrust:
1- To put the tongue in the palate so that it is just about to produce a “click.” The
tongue is held in this position and the tip of the tongue forced upwards. Should be
done in sets of 10, three times a day.
2- This exercise is called the “3-S’s”: slurp, squeeze, and swallow. The patient
is asked to collect saliva, which is the slurp; bring the teeth together and activate
muscles of closure, squeeze; and lastly, with the tongue in the click position, the
patient swallows.
Alexander(1999). Open bite, dental alveolar protrusion, Class I malocclusion:Asuccessful
treatmentresult.AJODO116:494-500
Measurements performed on the crib confirm the tongue adaptation to environmental
changes. Resting tongue pressures at the 12th month remained lower than the initial
values. These findings indicate adaptive behavior of the tongue to open bite closure
and the new position of the incisors.
Taslan et al (2010). Tongue pressure changes before, during and after crib appliance
therapy. Angle Orthod 80: 533-539
Protecting Teeth Surface
Bonding molars leads to better periodontal health than banding because of less
plaque accumulation.
Boyd and Baumrind (1992). Periodontal considerations in the use of bonds or bands on
molars in adolescents and adults. Angle Orthod 62: 117-26
The most significant contributors to the consumption of non-milk extrinsic sugars
are soft drinks, confectionery and biscuits and cakes.
Moynihan (2002). Dietary advice in dental practice. BDJ 193: 563-568

29
The patients using powered brushes had significantly lower plaque and calculus
scores compared to manual but no differences in attachment level.
Dentino et al (2002). Six-month comparison of powered versus manual tooth brushing for
safety and efficacy in the absence of professional instruction in mechanical plaque control.
JP 73: 770-778
Fluoride elastomers are ineffective in changing levels of streptococcal or anaerobic
growth. A prospective randomised clinical trial.
Benson et al (2004). Fluoridated elastomers: effect on the microbiology of plaque.AJODO
126:325-330
A short exposure to a low ph carbonated drink (Coca-Colas) caused a reduction
in microhardness of the enamel, the frequency of exposure to the drink was
inconclusive in microhardness reduction and that palatal and labial enamel were
equally susceptible to reduction in microhardness.
Van Eygen et al (2005). Influence of a soft drink with low pH on enamel surfaces: An in
vitro study. AJODO 128: 372-377
Topical fluorides in addition to fluoride toothpaste reduce decalcification in patients
wearing fixed appliances.
Chadwick et al (2005). The effect of topical fluorides on decalcification in patients with
fixed orthodontic appliances: A systematic review. AJODO 128: 601-606
Atriple headed brush is more effective in removing tooth plaque, bracket plaque and
gingival health than either conventional or orthodontic toothbrushes.
Rafe et al (2006). Comparative study of 3 types of toothbrushes in patients with fixed
orthodontic appliances. AJODO 130: 92-95

Section
Two
30
The use of interdental brushes is often recommended by orthodontists but there is no
evidence that this is an effective intervention.
Goh (2007). Interspace/interdental brushes for oral hygiene in orthodontic patients
with fixed appliances. Cochrane database of systematic reviews 2007, Issue 3. Art. No.:
CD005410. DOI: 10.1002/14651858. CD005410.pub2
Current evidence is insufficient to support the comparative efficacy of powered
toothbrushes in reducing gingivitis in patients undergoing fixed orthodontic
appliance therapy.
KaklamanosandKalfas(2008).Meta-analysisontheeffectivenessofpoweredtoothbrushes
fororthodonticpatients.AJODO133:187.e1–187.e14
Oral health promotion during orthodontic treatment has a positive effect. Patients
thought the single tufted brush required too much force to insert underneath the
archwire and the triangular brush too little. The triangular brush was perceived as
less painful and preferred by adolescents.
Gray and McIntyre (2008). Does oral health promotion influence the oral hygiene and
gingival health of patients undergoing fixed appliance orthodontic treatment? A systematic
literature review. JO 35: 262–269
Aprospective, randomized, observer-blind, split-mouth crossover clinical trial to determine
the effectiveness of two different types of interproximal brush:
A single tufted brush (TePe) in a long straight handle and a triangular interdental
brush (No. 6) made by elmex®:
No significant difference between the two types of brushes was seen.
Bock et al (2010). Plaque control effectiveness and handling of interdental brushes during
multibracket treatment- a randomized clinical trial. EJO 32: 408-413

31
Changes in mastication markedly affect mandibular condylar cartilage growth and
mandibular morphology. It is considered that dietary education at an early age is
important in order to prevent disruption of the development of the mandible.
Enomotoet al (2010). Effects of mastication on mandibular growth evaluated by
microcomputed tomography. EJO 32:66-70
The electric toothbrush, with either brush head, demonstrated significantly greater
plaque removal over the manual brush. The orthodontic brush head was superior to
the regular head.
Erbe et al (2013). Efficacy of 3 toothbrush treatments on plaque removal in orthodontic
patients assessed with digital plaque imaging: A randomized controlled trial. AJODO 143:
760–766
A relationship exists between body mass index (BMI) and dental and skeletal
development. BMI percentile, dental age difference, and cervical vertebral stage
are weakly correlated. No significant differences existed between boys and girls in
any variables. BMI percentile and ethnicity are weak predictors of the discrepancy
between dental age and chronologic age.
DuPlessisetal(2016).Relationshipbetweenbodymassanddentalandskeletaldevelopment
inchildrenandadolescents.AJODO150:268–273
Powered toothbrushes may promote gingival health better than manual toothbrushes
in orthodontic patients.
Al Makhmari et al (2017). Short-term and long-term effectiveness of powered toothbrushes
in promoting periodontal health during orthodontic treatment: A systematic review and
meta-analysis. AJODO 152: 753-766

Section
Two
32
A 2-arm parallel RCT trial. Plaque removal efficacy and the motivation assessment
comparing a manual versus an interactive power toothbrush in orthodontic patients:
An interactive power toothbrush (smartphone with Bluetooth technology) generated
increased brushing times and significantly greater plaque removal versus a manual
brush.
Erbe et al (2019). Comparative assessment of plaque removal and motivation between
a manual toothbrush and an interactive power toothbrush in adolescents with fixed
orthodontic appliances: A single-center, examiner-blind randomized controlled trial.
AJODO 155: 462-472
Possible Causatives of Malocclusions
Association between candidate polymorphisms and skeletal Class III malocclusion:
Polymorphism in MYO1H (rs10850110 AG) could be used as a marker for
genetic susceptibility to Class III malocclusion with mandibular prognathism,
and polymorphisms in GHR (rs2973015 AG) and FGF (rs593307 AG) were
associated with maxillomandibular discrepancies.
Vasconcellos Cruz et al (2017). Genetic polymorphisms underlying the skeletal Class III
phenotype. AJODO 151: 700-707
Association between signs of attention deficit-hyperactivity disorder and malocclusion in
schoolchildren:
The prevalence of malocclusion was higher among children with signs of
hyperactivity independently of age, pacifier use, and mouth breathing.
Mota-Veloso et al (2021). The prevalence of malocclusion is higher in schoolchildren with
signs of hyperactivity. AJODO 159: 653-659

33
Section Three
Treatment Planning
Analysis of Facial Esthetics
Occlusal Goals
Curve of Spee
Bolton Ratios
Lower Incisor Position
Smile Analysis
Extraction for Orthodontic Reasons

Treatment Planning
35
Analysis of Facial Esthetics
The Holdaway angle in its conventional definition is between soft tissue nasion-soft
pogonion and soft pogonion-labrale superius.
It is now officially recommended by the BOS clinical effectiveness committee as
one of seven cephalometric measures to audit the outcome of orthognathic cases.
Holdaway (1983). Soft tissue cephalometric analysis and its use in orthodontic treatment
planning. Part 1. AJODO 84:1-28
Holdaway (1984). Soft tissue cephalometric analysis and its use in orthodontic treatment
planning. Part 2. AJODO 85:279-293
Johnston et al (2006). Class III surgical-orthodontic treatment: A cephalometric study.
AJODO 130:300-9
Johnston reported using his pitchfork analysis that in a growing patient, a significant
part of class II molar relationship correction in a non-extraction case is due to
temporary inhibition of maxillary growth and continuing mandibular growth.
Livieratos and Johnston (1995).Acomparison of one-stage and two-stage non-extraction
alternatives in matched Class II samples.AJODO 108:118-31
The chin point should lie on a vertical line drawn halfway between subnasale and
A point.
Bass NM (2003). Measurement of the profile angle and the aesthetic analysis of the facial
profile. JO 30: 3-9
True vertical line (TVL) through subnasale. In cases of maxillary retrusion, moving
the TVL 1 to 3 mms anteriorly is suggested. Nasal tip projection relative to TVL is
(14.6-17.4) mm in adult females and (15.7-19.1) mm in adult males.
Arnett and McLaughlin (2004). Facial and Dental Planning for Orthodontists and Oral
Surgeons Edinburgh, Mosby

Section
Three
36
Jordanian soft tissue norms are similar to American norms with the exception of
the former having a more prominent upper lip position in relation to the overall soft
tissue profile.
Hamdan A (2010). Soft tissue morphology of Jordanian adolescents. Angle Orthod 80:
80-85
Establishing an ideal definition for the craniofacial midsagittal plane (MSP):
The nasion-basion-incisive foramen plane should be used for skull orientation and
3-dimensional cephalometric analyses because it approximates the MSP of best fit
with high accuracy.
Green et al (2017). A simple and accurate craniofacial midsagittal plane definition.
AJODO 152: 355-363
Perceptions of laypeople for digital alterations and the amount of nasolabial angle increase
that is tolerable and how much chin-neck length increase is needed to achieve a desirable
profile in Class II Division 1 women with mandibular retrognathia:
Nasolabial angle increases up to 121° seem to be acceptable.
Profiles simulating a chin-neck length increase as produced by surgery seem to be
most favored.
Yüksel et al (2017). Differences in attractiveness comparing female profile modifications
of Class II Division 1 malocclusion. AJODO 152: 471-476
Value-addition of obtaining lateral cephalometric radiographs during the treatment
planning phase of orthodontic treatment:
The lateral cephalometric radiograph is not a necessary diagnostic tool for most
cases in orthodontic diagnosis and treatment planning.
Weighing the usefulness of a lateral cephalometric on a case-by-case basis should
be recommended to align with the principle of ALARA (as low as reasonably
achievable), especially in a primarily pediatric population.
Dinesh et al (2020). Value-addition of lateral cephalometric radiographs in orthodontic
diagnosis and treatment planning. Angle Orthod 90(5):665–671

Treatment Planning
37
Orthodontists and OMFSs were more sensitive to perceive abnormality in the face
symmetry at 2 mm chin deviation than GDPs and laypersons (at 4 mm).
Also, orthodontists and OMFSs were more critical in detecting the reductions in the
LAFH at 48% compared to the other two groups with 46%.
For the increased LAFH variable, all dental professionals perceived the abnormality
at the 54% level, being more sensitive than the laypersons with a threshold of 56%
Alrbata et al (2020). Thresholds of Abnormality Perception in Facial Esthetics among
Laypersons and Dental Professionals: Frontal Esthetics. IJD 10.1155/8946063.
Orthodontists defined maxillary retrusion threshold of abnormality at −3 mm to
TVL being more sensitive than laypersons, GDPs, and OMFSs at −5 mm.
For maxillary protrusion, orthodontists, GDPs, and OMFSs detected the abnormality
in the positioning at +1 mm to TVL compared to +3 mm for the laypersons.
For mandibular retrusion, all groups perceived a threshold of −7 mm Pog to TVL
as abnormal.
For mandibular protrusion, dental professionals were more sensitive to perception
of the abnormality at which Pog was located at the TVL compared to the laypersons
who outlined that at 2 mm in front of the line.
Alrbata et al (2020). Thresholds of Abnormality Perception in Facial Esthetics among
Laypersons and Dental Professionals: Frontal Esthetics. IJD 10.1155/2068961
Occlusal Gaols
Andrews› Six Keys to normal (or optimal) occlusions.
Key 1 Correct interarch relationships
Key 2 Correct crown angulation (tip)
Key 3 Correct crown inclination (torque)
Key 4 No rotations
Key 5 Tight contact points
Key 6 Flat curve of Spee (0.0 - 2.5 mm)
Andrews LF (1972). The six keys to normal occlusion. AJODO 62: 296-309

Section
Three
38
Five degrees of incisor proclination would reduce the overbite by one mm on
average.
Eberhart et al (1990). The relationship between bite depth and incisor angular change.
The extra 2 degrees of tip (angulation) in the Roth prescription for the upper canine
(13 degrees) compared to Andrews standard (11 degrees) requires an approximate
extra 0.5 mm of arch length per side.
O’Higgins et al (1999). The influence of maxillary incisor inclination on arch length. BJO
26: 97-102
The WALA ridge (‘Will Andrews and Larry Andrews’) is the most prominent point
on the soft-tissue ridge immediately occlusal to the mucogingival junction.
Andrews and Andrews (2000). The six elements of orofacial harmony. AJ 1: 13-22
Every 5 degrees of incisor torque increased the upper arch length by 0.92 mm. A
close linear relationship between arch length and incisor inclination over a range
from 90 degrees to 130 degrees. This means that a 10 degree change in torque will
alter the molar relationship by approximately 1 mm on each side.
Sangcharearn and Hob (2007). Maxillary incisor angulation and its effect on molar
relationships. Angle Orthod 77:221-225
Children with increased body mass index did not cooperate as well during
multibracket therapy as their normal-weight peers, but the treatment outcome was
comparable in the two groups.
Bremen et al (2013). Correlation between body mass index and orthodontic treatment
outcome. Angle Orthod 83: 371-375

Treatment Planning
39
Comprehensive orthodontic treatment on average requires less than 2 years to
complete.
Tsichlaki et al (2016). How long does treatment with fixed orthodontic appliances last? A
systematic review. AJODO 149:308–318
Changes in dental arch dimensions, tooth size, and incisor crowding in subjects with
normal occlusion over a 40-year period:
Increases of clinical crown height in the posterior teeth and incisor crowding.
Decreases of mesiodistal tooth size, mandibular intercanine width, arch length, arch
perimeter, overbite, and curve of Spee.
Palatal depth increased from 13 to 17 years of age. No changes were observed for
overjet.
Massaro et al (2018). Maturational changes of the normal occlusion:A40-year follow-up.
AJODO 154: 188-200
Curve of Spee
Allow 1 mm space for 3 mm depth of curve, 1.5 mm for 4 mm depth, and 2 mm
space for a 5 mm curve.
Kirschen et al (2000). The Royal London Space Planning:An integration of space analysis
and treatment planning, Part 1.AJODO 118:448-455
A non-linear relationship and a less than one to one ratio for curves shallower than
9 mm.
Germane and Staggers (1992). Arch length considerations due to the curve of Spee: a
mathematical model. AJODO 102: 251-255

Section
Three
40
A very deep curve of 9 mm only requires 2 mm of additional space.
Braun et al (1996). The curve of Spee revisited. AJODO 110: 206-210
Inter-arch Tooth-width Discrepancies - Bolton Ratios
The extraction of four first premolars had a statistically and possibly clinically
significant effect on Bolton ratio, whilst extraction of four second premolars had
very little average effect.
Saatci and Yukay (1997). The effect of premolar extractions on tooth-size discrepancy.
AJODO 111: 428-434
Class II patients: a tendency to maxillary tooth-size excess.
Class III patients: a tendency to mandibular tooth-size excess.
Nie and Lin (1999). Comparison of intermaxillary tooth size discrepancies among different
malocclusiongroups.AJODO116:539-544
Bolton’s ratios only apply well to white females who probably made up Bolton’s
entire original sample.
Smith et al (2000). Interarch tooth size relationships of three populations: “Does Bolton’s
analysis apply?” AJODO 117: 169-174
Proffit suggested 1.5 mm as a level at which a clinically significant Bolton
discrepancy effect may result.
Proffit WR (2000). Contemporary Orthodontics. Mosby Inc. St Louis page 170

Treatment Planning
41
The original Bolton ratio norms are unlikely to be an ideal guide to the presence or
absence of a clinically significant problem in all populations.
Alkofide and Hashim (2002). Intermaxillary tooth size discrepancies among different
malocclusion classes: A comparative study. JCPD 26: 383-388
Bolton discrepancy has very little correlation with aspects of the start or finishing
occlusion and is therefore of very little diagnostic assistance.
Redahan and Lagerstrom (2003). Orthodontic treatment outcome: the relationships
between anterior dental relations and anterior inter-arch tooth size discrepancy. JO 30:237-
244
A significantly higher mean ratio (mandibular tooth excess) is found in class III
cases and a lower percentage of significant Bolton discrepancy in class II cases.
Araujo and Souki (2003). Bolton anterior tooth size discrepancies among different
malocclusion groups. Angle Orthod 73:307-313
2 mm of correction is a threshold for clinical significance and, in a random sample
of British orthodontic patients, 25% of patients required such a correction for an
ideal total arch ratio and 12% for the anterior ratio
Othman and Harradine (2007). Tooth size discrepancies in an orthodontic population.
Angle Orthod 77: 668–674.
2mm is a threshold for clinical significance.
Endo et al (2009). Thresholds for clinically significant tooth-size discrepancy. Angle
Orthod 79: 740-746

Section
Three
42
Lower Incisor Position
Leave the average incisor labiolingual position unchanged during treatment.
Mills (1968). The stability of the lower labial segment. Dental Practitioner 18: 293-306
To maximize stability of incisors relationship: Correct edge- centroid relationship
(lower incisor edge should lie anterior to the upper root centroid).
Houston (1989). Incisor edge-centroid relationships and overbite depth. EJO 11;139-143
The APo line is not a position of lower incisor stability. In 62% of cases the incisors
tended to return towards their startingA-P position.
Houston and Edler (1990). Long term stability of the lower labial segment relative to the
A-Pog line. EJO 12: 302-310
Cases which had been treated with an average of 2.8 mm more lower incisor
proclination than another matched group of cases, finished with slightly greater
irregularity (Little’s index) out of retention.
Paquette et al (1992). A long-term comparison of non-extraction and premolar extraction
edgewise therapy in “borderline” Class II patients. AJODO 102: 1-14
A similar tendency for incisors moved labially during treatment to return towards
their starting position, but that modest retroclination of incisors was stable or even
increased post-retention. Invasion of the space previously occupied by the tongue is
more stable than invasion of lip or cheek space.
Sims and Springate (1995). Stability of the lower labial segment following orthodontic
treatment--a comparison of treatment with Andresen and Begg appliances. BJO 22: 13-21

Treatment Planning
43
Lower incisor proclination might prove to be stable in those patients in whom the
mandible is expected to develop in an anterior rotational pattern according to the
morphological features described by Bjork.
Williams and Andersen (1995). Incisor stability in patients with anterior rotational
mandibular growth. Angle Orthod 65: 431-442
Lips cannot know which incisor is touching them, therefore we can procline the
lower incisor in class II division 2 cases to touch the lower lip at the same A-P
position as was occupied before treatment by the extruded upper incisor.
Selwyn-Barnett (1996). Class II division 2 malocclusion: A method of planning and
treatment. BJO 23: 29-36
Incisors proclined an average of 11 degrees or 3.2 mm retroclined an average of
8 degrees or 2.5 mm respectively in the following six months when no appliances
were in place.
Hansen et al (1997). Long-term effects of Herbst treatment on the mandibular incisor
segment: A cephalometric and biometric investigation. AJODO 112: 92-103
An approximate limit of 2 mm for labial movement of the lower incisors is feasible
if anteroposterior stability is the main factor influencing our decision.
Ackerman and Proffit (1997). Soft tissue limitations in orthodontics: Treatment planning
guidelines. Angle Orthod 67: 327-336
70% of the proclination produced by Jasper Jumpers subsequently relapsed.
Stucki and Ingervall (1998). The use of the Jasper Jumper for the correction of Class II
malocclusion in the young permanent dentition. EJO 20: 271-281

Section
Three
44
Proclining lower incisors in class II division 2 cases leads to much more relapse of
arch irregularity than when the arch length was not increased.
Canut and Arias (1999). A long-term evaluation of treated Class II division 2
malocclusions: a retrospective study model analysis. EJO 21:377-386
Lower incisor inclination is linked to the subject’s sex, age, and skeletal pattern. It
is not associated with symphyseal dimensions, except symphyseal depth. Factors
related to natural inclination of lower incisors should be respected when establishing
a treatment plan.
Gütermann et al (2014). The inclination of mandibular incisors revisited. Angle Orthod
84:109-119
Incisor crowding reduction can be expected from the early mixed to the early
permanent dentition. The potential for crowding reduction was associated with
greater initial incisor crowding, leeway space, incisor protrusion, and maxillary
width increase. A crowding threshold of 2 mm was not a valid borderline condition
to define the self-correction prognosis.
Barros et al (2016). Impact of dentofacial development on early mandibular incisor
crowding. AJODO 150: 332–338
Smile Analysis
Buccal corridor ratio = Inner commissure width ̶ Visible maxillary dentition / Inner
commissure width ×100
Frush and Fisher (1958). The dynesthetic interpretation of the dentogenic concept. JPD
8: 558-581

Treatment Planning
45
Buccal corridor ratio = Frontal intercanine width/ Commissure width.
Hulsey (1970). An aesthetic evaluation of lip-teeth relationships present in smile. AJODO
57: 132-144
The upper central incisors, lateral incisors and canines are in the golden proportion
(1:0.618).
Levin (1978). Dental esthetics and the golden proportion. JPD 40: 244-253
In aesthetic rank, smiles which show first molar to first molar are judged the most
attractive followed by smiles which show second premolar to second premolar and
second molar to second molar.
Tjan et al (1984). Some aesthetic factors in a smile. JPD 51: 24-28
Yoon et al (1992). A study on the smile in Korean youth. JKAP 30: 259-270
Amount of maxillary gingivae displayed is the most important feature of a smile
that affects aesthetics and is also affected by orthodontics is.
Johnson and Smith (1995). Smile aesthetics after orthodontic treatment with and without
extraction of four first premolars. AJODO 108: 162-7
Upper incisor exposure becomes less and lower incisor exposure becomes greater
with aging.
Chio et al (1995). A study on the exposure of maxillary and mandibular central incisor in
smiling and physiologic rest position. JWDRI 5: 371-379
Dong et al (1999). The aesthetics of the smile: a review of some recent studies. IJP 12:
9-19

Section
Three
46
Influence of animation on smile characteristics: Women show greater facial
animation than men. Orthodontically treated patients had more upper incisor
exposure on smiling and also a greater interlabial gap.
Rigsbee et al (1988). The influence of facial animation on smile characteristics. IJAOOS
3: 233-239
Smile index: intercommisure width/ interlabial gap on smiling.
Ackerman et al (1998). Amorphometric analysis of the posed smile. Clinical Orthodontics
and Research 1: 2-11
An open space between incisors had to be 2 mm wide before orthodontists perceived
it as unattractive and lay people did not notice an open gingival embrasure until it
was 3 mm long.
Kokich et al (1999). Comparing the perception of dentists and lay people to altered dental
esthetics. JED 11: 311-324
The prevalence of open gingival embrasures is 38% in adult orthodontic patients.
Kurth and Kokich (2001). Open gingival embrasures in adults after orthodontics
treatment: prevalence and etiology. AJODO 120: 116-123
The aesthetics of smiles in extraction and non-extraction cases without arch
expansion were compared and find no difference between the two groups.
Kim and Giannelly (2003). Extraction versus non-extraction: arch widths and smile
aesthetics. Angle Orthod 73: 354-358

Treatment Planning
47
Useful information can be obtained from an oblique or three-quarter photograph. In
particular, the relationship of the occlusal plane to the curve of the lower lip and the
display of the upper maxillary teeth, including the premolars and molars which are
not visible from the frontal view.
Sarver and Ackerman (2003b). Dynamic smile visualization and quantification: Part 2.
Smile analysis and treatment strategies. AJODO 124: 116-127
The appearance of small buccal corridors is preferred by lay judges.
Moore et al (2005). Buccal corridors and smile aesthetics. AJODO 127:208-13
Excessive buccal corridors and smile arcs were rated less attractive by both
orthodontists and lay persons. In addition, flat smile arcs decreased attractiveness
regardless of the buccal corridor width.
Parekh et al (2006). Attractiveness of variations in the smile arc and buccal corridor space
as judged by orthodontists and laymen.Angle Orthod 76: 557-563
Both lay people and orthodontists prefer smiles with smaller buccal corridors.
Martin et al (2007). The impact of buccal corridors on smile attractiveness. EJO 29: 530-
537
Predictors of change in lip shape and NLA with upper incisor correction in class II
cases. A large range of change in NLA (40 degrees) and no correlation with incisor
A-P change.
Tadic and Woods (2007). Incisal and soft tissue effects of maxillary premolar extraction
in class II treatment . Angle Orthod 77: 808–816

Section
Three
48
No relationship between BCS or upper incisor exposure and smile aesthetics as
rated by both lay persons and orthodontists.
McNamara et al (2008). Hard- and soft-tissue contributions to the aesthetics of the posed
smile in growing patients seeking orthodontic treatment. AJODO 133: 491-499
Both orthodontists and dental students preferred broader smiles (buccal corridor
ratio 10%) and that above 10%, the difference in perception became clinically
significant.
Ioi et al (2009). Effects of buccal corridors on smile esthetics in Japanese. Angle Orthod
79: 628-633
Maxillary incisor display decreased with age but the smile index increased
significantly.
Desai et al (2009). Dynamic smile analysis: Changes with age. AJODO 136:310.e1-10
Lay judges prefer smaller BCS.
Ioi et al (2009). Effects of buccal corridors on smile esthetics in Japanese. Angle Orthod
79:628-636
Thereisasyetnoconvincingevidencethatbuccalcorridorsaffectsmileattractiveness.
Springer et al (2011). Smile esthetics from the lay perspective. AJODO 139: e91-e101

Treatment Planning
49
Semi-quantitative categorization of smile line:
• 75% of incisor crown height showing is a low smile line.
• 75% to 100% of the incisor crown height showing is a normal smile height.
• Showing the total incisor crown length of a tooth and a continuous band of
gingiva (minimum of 1 mm) is classified as a high smile line
• A lip line more than 4mm of gingiva is classified as a gummy smile line.
Van der Geld et al (2011). Smile line assessment comparing quantitative measurement
and visual estimation. AJODO 39: 174-180
A small dental midline deviation of 2.2 mm can be considered acceptable by both
orthodontists and laypeople, whereas an axial midline angulation of 10° (2 mm
measured from the midline papilla and the incisal edges of the incisors) is already
very apparent. No research on actual subjects as yet supports the view that buccal
corridor sizes and smile arc alone influences smile attractiveness.
Janson et al (2011). Influence of orthodontic treatment, midline position, buccal corridor
and smile arc on smile attractiveness. Angle Orthod 81: 153-161
Persons with ideal smiles are considered more intelligent and have a greater
chance of finding a job when compared with persons with nonideal smiles.
Pithon et al (2014). Do dental esthetics have any influence on finding a job? AJODO 146:
423–429
Extraction for Orthodontic Reasons
Planning Extractions:
Extraction is minimally adopted in low angle cases as space closure is difficult.
Moller (1966). The chewing apparatus, Acta Physiol Scand, 69; Supplement 280

Section
Three
50
Avoid extraction of teeth in low MMP angle cases as space closure is difficult.
Bjork Skieller ( 1972). Facial development and tooth eruption. An implant study at the
age of puberty. AJODO 62:339-383
Comparing premolar and second molar extractions:
Differences in the A-P changes in incisor position but no differences in the changes
in soft-tissue facial convexity or of the upper lip relationship to a soft-tissue APo
line.
Staggers JA(1990). Acomparison of second molar and first premolar extraction treatment.
AJODO 98: 430-436
An average of 1.4 mm posterior movement of the upper lip when the upper incisors
were retracted by an average of 5.0 mm, an average ratio of 28%.
As a rule of thumb, extraction of first premolars provides approximately 66% of
the space for aligning/retracting the anterior teeth, whereas extraction of second
premolars provides approximately half of the space.
Creekmore (1997). Where teeth should be positioned and how to get them there. JCO
31:586-608
The extraction of first premolars successfully accommodates twice the crowding
than do the extraction of second premolars.The average lower incisor anteroposterior
change is not different.
Saelens and De Smit (1998). Therapeutic changes in extraction versus non-extraction
orthodontic treatment. EJO 20:225-230

Treatment Planning
51
Lower 1st molar: extraction timing is critical, maximum spontaneous space closure
is likely to occur when bifurcation of 2nd molar is visible on radiograph.
Sandler et al (2000). For four sixes. AJODO 117:418-34
Extraction of 1st molars may be delayed and temporized if space is required for
correction of malocclusion later. Interceptively; commonly removed between 8-10
yrs. but dental age of patient is more important. For upper 1st molars: timing of
extraction is less critical than lower extraction as rapid mesial movement of 2nd
molars due to distal angulation of follicle.
Gill et al (2001). Treatment planning for the loss of first permanent molars. Dent Update
28:304-308
More anchorage is provided in the upper arch by extraction of 4s than by extraction
of 5s.
Ong and Woods (2001). An occlusal and cephalometric analysis of maxillary first and
second premolar extraction effects. Angle Orthod 71: 90-102
The average ratio of movement is 1:4 for lip: incisor change.
Kusnoto and Kusnoto (2001). The effect of anterior tooth retraction on lip position of
orthodontically treated adult Indonesians. AJODO 120: 304-307
Amount of crowding affect extraction decision:
• 0-4mm mild
• 5-9mm moderate
• 10mm severe
Proffit WR et al (2007). Contemporary Orthodontics, 4th Ed, Mosby

Section
Three
52
Extraction of the maxillary first molars in Class II Division 1 patients results in
significant uprighting of 2nd molar and 3d molar and facilitates the normal eruption
of 3d molar.
Livas et al (2011). Extraction of maxillary first molars improves second and third molar
inclinations in Class II Division 1 malocclusion. AJODO 140: 377–382
When the inclination of the third molar is inconvenient, the tooth may remain
impacted even if there is enough retromolar space.
Türköz and Ulusoy (2013). Effect of premolar extraction on mandibular third molar
impaction in young adults. Angle Orthod 83:572-577
A trend was observed in which clinicians with more experience chose an extraction
treatment option more frequently in borderline cases than did those with less
experience. Clinicians’ gender did not play a role in extraction decision making.
Saghafi et al (2017). Influence of clinicians’ experience and gender on extraction decision
in orthodontics. Angle Orthod 87(5):641–650
Extractions and Facial Aesthetics:
Extraction leads to lower incisors averaging 2 mm more posterior than the in non-
extraction with lower lip further behind E line.
Patients treated with extractions had on average slightly more prominent lips at the
end of treatment than those treated on a non-extraction basis.

Treatment Planning
53
Luppanapornlap and Johnston (1993). The effects of premolar extraction: a long term
comparison of outcomes in “clear-cut” extraction and non-extraction Class II patients.
Angle Orthod 63: 257-272
James (1998). A comparative study of facial profiles in extraction and non-extraction
treatment. AJODO 114: 265-76
Standards of facial attractiveness had changed with a trend towards more protrusive
lips and increase in vermilion display.
Auger and Turley (1994). Esthetic soft tissue profile changes during the 1900s. JDR 73:
2128
No difference between orthodontists and general dental practitioners in their
judgments of whether patients who had a concave facial profile had had extractions
or not.
Rushing et al (1995). How dentists perceive the effects of orthodontic extraction on facial
appearance.JADA126: 769-772
Small extra lip retraction with extractions when compared with non-extraction
cases, but since extractions had been chosen in cases with slightly more prominent
lips, the final average soft tissue profile was identical in both groups.
Zierhut et al (2000). Long-term profile changes associated with successfully treated
extraction and non-extraction Class II division I malocclusions. Angle Orthod 70: 208-219
Wide variety of anteroposterior changes in lower incisor position which occurs for
all combinations of premolar extractions.
Shearn and Woods (2000). An occlusal and cephalometric analysis of lower first and
second premolar extraction effects. AJODO 117:351-61

Section
Three
54
2 groups with equivalent starting irregularity index treated with and without premolar
extractions:
The increase in the area bounded by the lower labial segment relapsed more in the
non-extraction group, but the relapse in Irregularity index was the same in both .
Heiser et al (2004). Three-dimensional dental arch and palatal form changes after
extraction and non-extraction treatment. Part 1. Arch length and area. AJODO 126:71-81
Extraction of four premolars can be effective in decreasing the soft tissue
procumbency in bimaxillary protrusion cases.
Bills et al (2005). Bimaxillary dentoalveolar protrusion: traits and orthodontic correction.
Long-term study over 25 years found that treatments involving extractions produced
much less relapse of crowding in both arches when compared with non-extraction
cases, particularly in the lower arch.
Jonsson and Magnusson (2010). Crowding and spacing in the dental arches: long term
development in treated and untreated subjects. AJODO 138:384e1-384e7
Extraction lead to an average of 2 mm greater retraction of the lower lip relative to
E line and an increase of 5 degrees in the NLA compared to no change for this angle
in the non-extraction group.
Konstantonis (2012). The impact of extraction vs. nonextraction treatment on soft tissue
changes in Class I borderline malocclusions. Angle Orthod 82(2):209-217
Extraction of first premolars for the treatment of bimaxillary proclination does not
affect upper airway dimensions despite the significant reduction in tongue length
and arch dimensions.
Al Maaitah et al (2012). First premolar extraction effects on upper airway dimension in
bimaxillary proclination patients. Angle Orthod 82: 853-859

Treatment Planning
55
Greater maxillary crowding relapse in the nonextraction cases and greater overbite
relapse in the extraction cases. Many significant and positive correlations of overjet
and overbite relapses with mandibular anterior crowding relapse and consequently
between overjet and overbite relapses.
Francisconi et al (2014). Overjet, overbite, and anterior crowding relapses in extraction
and nonextraction patients, and their correlations. AJODO 146: 67–72
There was a high prevalence of space reopening 1 year after treatment. However,
these spaces tended to decrease by 5 years after treatment.
Garib et al (2016). Stability of extraction space closure. AJODO. 149: 24–30
Effects of orthodontic treatment with 4 premolar extractions on the skeletal vertical
dimension of the face compared with nonextraction treatment:
Orthodontic treatment with 4 premolar extractions has no specific effect on the
skeletal vertical dimension. Thus, an extraction treatment protocol aiming to reduce
or control the vertical dimension does not seem to be an evidence-based clinical
approach.
Kouvelis et al (2018). Effect of orthodontic treatment with 4 premolar extractions
compared with nonextraction treatment on the vertical dimension of the face: A systematic
review. AJODO 154: 175-187
Extractions and Smile Width:
No evidence that orthodontic treatment involving extractions cause larger BCSs.
Also no evidence that extractions produced less attractive smiles in the opinions of
lay judges.
Johnson and Smith (1995). Smile aesthetics after orthodontic treatment with and without
extraction of four first premolars. AJODO 108: 162-7

Section
Three
56
A non-extraction group was compared with an extraction of four first premolars
group. The principal finding was that post-treatment, canine, premolar and widest
molar widths were essentially the same in the two groups.
Gianelly (2003). Arch width after extraction and non-extraction. AJODO 123:25-8
At constant arch depth, the extraction group was slightly wider after treatment than
were the non-extraction group.
Gianelly (2003). Extraction vs non-extraction: Arch width and smile aesthetics. Angle
Orthod 73:354-358
No effect of extractions on the buccal corridor space (BCS).
Yang et al (2008). Which hard and soft tissue factors relate with the amount of buccal
corridor space during smiling? The Angle Orthod 78: 5–11
The studies by Gianelly are good research which does indeed support the view that
premolar extractions per se do not have a detrimental effect on smile aesthetics.
Based on studies of actual subjects, BCS on its own has not yet been shown to be a
factor in smile attractiveness.
Janson et al (2011). Influence of orthodontic treatment, midline position, buccal corridor
and smile arc on smile attractiveness. Angle Orthod 81: 153-161
Post treatment changes in arch-width and perimeter measurements of borderline Class I
cases treated by Extraction vs nonextraction:
Patients treated with extraction of 4 first premolars had decreased maxillary and
mandibular intermolar and perimeter measurements compared with nonextraction
patients. The maxillary and mandibular intercanine widths showed no significant
difference between the 2 treatment groups.
Herzog et al (2017). Arch-width changes in extraction vs nonextraction treatments in
matched Class I borderline malocclusions. AJODO 151: 735-743

Treatment Planning
57
The amount and frequency of extraction space reopening after 2- and 4-premolar extraction
treatments in Class II and 4-premolar extractions in Class I malocclusion patients:
Long-term differences in frequency and amount of space reopening were not seen.
Janson et al (2017). Prevalence of extraction space reopening in different orthodontic
treatment protocols. AJODO 152: 320-326
No statistically significant difference was found in the smile attractiveness between
canine extraction and premolar extraction patients as assessed by general dentists,
laypeople, and orthodontists.
Thiruvenkatachari et al (2017). Extraction of maxillary canines: Esthetic perceptions of
patient smiles among dental professionals and laypeople. AJODO 152: 509-515
Anterior tooth alignment and dental arch dimension changes after orthodontic treatments
with and without premolar extractions in the long-term (37 year):
No difference in the changes of anterior alignment and transverse arch dimensions
in patients treated with and without premolar extraction.
The percentage of mandibular tooth alignment change was greater in the
nonextraction group.
Mandibular arch perimeter decreased more than in the extraction group.
Cotrin et al (2020). Anterior tooth alignment and arch dimensions changes: 37-year
follow-up in patients treated with and without premolar extraction. AJODO 158: e5-e15

59
Section Four
Early Orthodontic Treatment

61
Reliability and effectiveness of early orthodontic treatment will be researched here.
Favourable or highly favourable short-term mandibular growth was exhibited by
83% of functional appliance cases but also by 31% of the untreated controls.
Tulloch et al (1997a). Influences on the outcome of early treatment for Class II
malocclusion. AJODO 111:533-42
A small (0.6 degrees/year) enhancement of mandibular growth in the short term, but
none in the longer term.
Tulloch et al (1997b). The effect of early intervention on skeletal pattern in Class II
malocclusion: A randomised clinical trial. AJODO 111: 391-400
Tulloch et al (1998). Benefit of early Class II treatment: Progress report of a two-phase
randomised clinical trial. AJODO 113: 62-72
Early correction of skeletal problems: favorable changes inAP relationship achieved
but may not be clinically significant.
O›Brien et al (2003a). Effectiveness of early orthodontic treatment with the Twin-block
appliance: a multicenter randomized controlled trial. Part 1: Dental and skeletal effects.
AJODO 124:234-243
Early treatment with a twin-block and no early treatment: found exactly 1 mm of
average additional horizontal mandibular growth.
O’Brien et al (2003b). The effectiveness of early treatment for Class II malocclusion with
the Twin Block appliances: A multicenter randomized controlled trial. Part 1:dental and
skeletal effects. AJODO 124:234-243

Section
Four
62
Comparing early versus late treatment concluded: All groups experienced incisors
trauma and that very early treatment may prevent trauma but not cost effective.
Koroluk et al (2003). Incisor trauma and early treatment for Class II division 1
malocclusions. AJODO 123:117-126
The psychosocial effects of early twin-block treatment:
A significant benefit from treatment in terms of increased self-concept scores and
reduced negative social experiences. Immediately after twin block treatment the
profiles of children who had received early treatment were perceived to be more
attractive by their peers than those of children who did not receive treatment.
O’Brien et al (2003c). Effectiveness of early orthodontic treatment with the twin-block
appliance: A multicentre randomized controlled trial. Part 2: psychosocial effects 124:
488-495
Definite early benefits of early functional or headgear treatment did not result in any
shorter or simpler second phase treatment or any better final result. Early functional
treatment doubled the later rate of extractions in phase 2.
Tulloch et al (2004). Outcome in a 2-phase randomised clinical trial of early class II
treatment. AJODO 125:657-67
Early treatment is no more effective than orthodontic treatment in early adolescence.
Harrison et al (2007). Orthodontic treatment for prominent upper front teeth in children.
Cochran Database Systematic Review, CD003452
Appropriate early treatment may reduce the need for specialist orthodontic treatment
later.
Kerosuo et al (2008). The 7 year outcome of an early orthodontic treatment strategy. JDR
87: 584-588

63
In the long term there were no differences of skeletal pattern between those who
received early (average age 9 years) Twin-block treatment and those who had one
course of treatment in adolescence.
O’Brien et al (2009a). Early treatment for Class II Division 1 malocclusion with the
Twin-block appliance: A multi-center, randomized, controlled trial. AJODO 135:573-579
The early start to treatment provided no long–term advantages in terms of skeletal
pattern, self-esteem, or significant reduction in extraction rate. On the contrary,
those who had the early start to treatment had more attendances, received treatment
for longer times, had significantly poorer final dental occlusion and incurred
substantially greater costs than those who started at age 12.
O’Brien et al (2009a). Early treatment for Class II Division 1 malocclusion with the
Twin-block appliance: A multi-center, randomized, controlled trial. AJODO 135:573-579
Early orthodontic treatment did not affect the incidence of incisor injury.The majority
of the injuries before and during treatment were minor; therefore, the cost-benefit
ratio of orthodontic treatment primarily to prevent incisor trauma is unfavorable.
Chen et al (2011). Effect of early Class II treatment on the incidence of incisor trauma.
AJODO 140: e155–e160
Orthodontic treatment for young children, followed by a later phase of treatment
when the child is in early adolescence, appears to reduce the incidence of new
incisal trauma significantly compared with treatment that is provided in 1 phase
when the child is in early adolescence.
There are no other advantages in providing 2-phase treatment compared with 1
phase in early adolescence.
Thiruvenkatachari et al (2015). Early orthodontic treatment for Class II malocclusion
reduces the chance of incisal trauma: Results of a Cochrane systematic review. AJODO
148:47–59

Section
Four
64
There is a moderate amount of evidence to show that early treatment with a facemask
results in positive improvement for both skeletal and dental effects in the short term.
However, there was lack of evidence on long-term benefits.
Woon and Thiruvenkatachari (2017). Early orthodontic treatment for Class III
malocclusion: A systematic review and meta-analysis. AJODO 151: 28-52
Impact of Orthodontics on the oral health-related quality of life (OHRQoL):
low and moderate evidence that Orthodontic treatment during childhood or
adolescence leads to moderate improvements in the emotional and social well-being
dimensions of OHRQoL.
Javidi et al (2017). Does orthodontic treatment before the age of 18 years improve oral
health-related quality of life? A systematic review and meta-analysis. AJODO 151: 644-
655
Therapeutic and adverse effects of early headgear treatment:
Based on high quality evidence, headgear treatment is associated with a short-
term reduction of the SNA angle. Therefore, headgear might seem like a viable
and effective treatment option for the management of Class II malocclusion with
maxillary prognathism.
Based on evidence of moderate quality, treatment with headgear might decrease
the risk of dental trauma during the subsequent years, so this should be taken into
account when planning the Class II treatment of patients in high risk of dental
trauma.
Papageorgiou et al (2017). Effectiveness of early orthopaedic treatment with headgear: a
systematic review and meta-analysis. EJO 39:176–187
EarlytreatmenteffectivelyreducedthecomplexityofClassI,II,andIIImalocclusions
andaccountedfor57%,64%,and76%ofthetotalcorrection,respectively.
Class III group responded most favorably to early treatment followed by the Class
II group.
Pangrazio-Kulbersh et al (2018). Comparison of early treatment outcomes rendered in
three different types of malocclusions. Angle Orthod 88(3):253–258

65
Do age-dependent biologic responses to orthodontic force correlate with the rate of tooth
movement?
Cytokine and osteoclast markers increased significantly in adolescents and adults in
the first weeks of orthodontic force application. Increases in cytokine and osteoclast
markers are greater in adults than in adolescents in response to the same orthodontic
force level. The rate of tooth movement in adults is slower than in adolescents.
Adults report more pain and discomfort than adolescents in response to same force
level.
Alikhani et al (2018). Age-dependent biologic response to orthodontic forces. AJODO
153: 632-644

67
Section Five
Anchorage in Orthodontics
Conventional Mechanics
Orthodontic Microimplants (OMIs)

69
This section is concerned with anchorage philosophy in orthodontics. Conventional
mechanics and orthodontic microimplants will be covered in this section.
Conventional Mechanics
Lingual arches did not prevent mesial migration of molars even when no intra-arch
traction was applied, proclination of lower incisors occur.
Rebellato et al (1997). Lower arch perimeter preservation using the lingual arch. AJODO
112:449-456
No enhancement of vertical or horizontal anchorage when using utility arches to set
up cortical anchorage.
Ellen et al (1998). A comparative study of anchorage in bioprogressive versus standard
edgewise treatment in Class II correction with intermaxillary elastic force. AJODO
114:430-6
Slightly more anchorage loss when trans-palatal arches were used. However, they
were effective in rotating the first molars into a more favorable position for Class II
correction.
Radkowski (2007). The influence of the transpalatal arch on orthodontic anchorage.
Thesis abstract from St Louis University. AJODO 132: 562
TPA does not provide a significant effect on either the anteroposterior or the vertical
position of the maxillary first molars during extraction treatment.
Zablocki et al (2008). Effect of the transpalatal arch during extraction treatment. AJODO
133: 852-860

Section
Five
70
The lingual arch is effective for controlling mesial movement of molars and lingual
tipping of incisors.
Viglianisi A. (2010). Effects of lingual arch used as space maintainer on mandibular arch
dimension: A systematic review. AJODO 138: 382.e1–382.e4
No any preference in the use of Goshgarian or Nance palatal arch, unless the slightly
reduced patient discomfort with the Goshgarian arch is considered significant.
Stivaros et al (2010). A randomized clinical trial to compare the Goshgarian and Nance
palatal arch. EJO 32: 171-176
Effectiveness of LLHA:
The lower incisors proclined and moved forward, and space loss of the lower
primary second molar occurred. The LLHA made of 0.9 mm SS was superior to that
made of 1.25 mm SS in terms of arch length preservation.
Owais et al (2011). Effectiveness of a lower lingual arch as a space holding device. EJO
33: 37-42
TPA alone does not provide sufficient anchorage during en masse or for two-step
retraction cases when maximum anchorage is sought.
Diar-Bakirly et al (2017). Effectiveness of the transpalatal arch in controlling orthodontic
anchorage in maxillary premolar extraction cases: A systematic review and meta-analysis.
Angle Orthod 87(1):147–158.

71
Orthodontic Microimplants (OMIs)
Brånemark and colleagues introduced the concept of osseointegration, using
pure titanium implants, defining osseointegration as ‘living bone in direct contact
with a loaded implant surface.’
Brånemark et al (1969). Intra-osseous anchorage of dental prostheses. I. Experimental
studies Scandinavian. JPRS 3: 81–100
Kanomi described the use of titanium mini fixation screws in 1997.
Kanomi R (1997). Mini implant for orthodontic anchorage. JCO 31: 763-767
Screw length does not seem to be a factor in stability if the screw is more than 5 mm
long (intraosseous length).
Miyawaki et al (2003), Factors associated with the stability of titanium screws placed in
the posterior region for orthodontic anchorage. AJODO 124: 373-378
Park et al (2006). Factors affecting the clinical success of screw implants used as
orthodontic anchorage. AJODO 130: 18-25
Kuroda et al (2007). Clinical use of miniscrew implants as orthodontic anchorage: Success
rates and postoperative discomfort.AJODO 131: 9-15
A high MM angle was reported as a failure factor in the mandible by (Miyawaki
et al) who attributed this to the thinner cortical bone in patients, but (Kuroda 2007)
found no such association with MM angle.
Miyawaki et al (2003). Factors associated with the stability of titanium screws placed in
the posterior region for orthodontic anchorage. AJODO 124: 373-378

Section
Five
72
Miniscrew implants can be used buccally and palatally in the maxilla to facilitate
molar intrusion.
Park et al (2004). Treatment of open bite with microscrew implant anchorage. AJODO
126: 627-136
Park et al (2006). Nonextraction treatment of an open bite with microscrew implant
anchorage. AJODO 130: 390-402
Nonkeratinized mucosa is a risk factor for miniscrew failure.
Cheng et al (2004). A prospective study of the risk factors associated with failure of mini-
implants used for orthodontic anchorage. IJOMI 19: 100-106
Most studies report OMI success rates between 80% and 96%
Park et al (2005). Group distal movement of teeth using microscrew implant anchorage.
AJODO 75: 602-609
The literature supports the view that impinging on cementum and dentine is followed
by repair in most instances, showed almost total repair 12 weeks after removing
screws from beagle dogs.
Asscherickx et al (2005). Root repair after injury from mini-screw. COIR 16: 575-578
To raise the success rate of 1.6mm diameter mini- implants, the recommended
placement torque is within the range from 5 to 10 Ncm.
Motoyoshi et al (2006). Recommended placement torque when tightening an orthodontic
mini-implant. COIR 17: 109–114

73
OMIs vs miniplates:
Slightly higher percentage success rate with miniplates than with OMIs, but also
significantly more discomfort associated with their insertion and the necessary flap
being raised.
No correlation between success and lack of peri-implant inflammation.
Most authors report that inflammation is more likely if screws are placed in non-
attached mucosa and advise placement in or very close to attached gingiva.
Owens et al (2007). Experimental evaluation of tooth movement in the beagle dog with
the mini-screw implant for orthodontic anchorage. AJODO 132: 639-646
An experimental study on ten patients was encouraging that any root damage shows
rapid repair once the screw contact is removed.
Kadioglu et al (2008). Contact damage to root surfaces of premolars touching miniscrews
during orthodontic treatment.AJODO 134:353-360
Smaller diameter screws are much more likely to fracture.
Chen et al (2008). Biomechanical and histological comparison of self-drilling and self-
tapping orthodontic microimplants in dogs. AJODO 133: 44-50
For intrusion of posterior teeth miniplates seem to be a very reliable technique.
De Clerck et al (2008). Biomechanics of skeletal anchorage. Part 3. Intrusion. JCO 42:
270-278

Section
Five
74
Generally higher bone density in the mandible than the maxilla.
Park et al (2008). Density of the alveolar and basal bones of the maxilla and the mandible.
AJODO 133: 30-37
The effects of J-hook headgear and miniscrews on incisor intrusion; there were
significantly greater reductions in overbite, maxillary incisor to palatal plane, and
maxillary incisor to upper lip in the implant group than in the J-hook headgear
group; mean intrusion for the miniscrew group was 3.6 mm and 1.1 mm for the
J-hook headgear group. Furthermore, significantly less root resorption was observed
in the implant group compared with the J-hook headgear group.
Deguchi et al (2008). Comparison of the intrusion effects on the maxillary incisors between
implant anchorage and J-hook headgear.AJODO 133: 654-660
The safest interradicular site in the maxilla is between the second premolar and the
first molar, from 6 to 8 mm from the cervical margin.
Hu et al (2009). Relationships between dental roots and surrounding tissues for orthodontic
miniscrewinstallation.AngleOrthod79:37-45
A21%incidenceofrootcontactforinexperiencedoperatorsand13%forexperienced
operators. The surgery site and clinicians’ expertise had significant effects on the
rate as well as the pattern of root contacts.
Cho et al (2010). Root contact during drilling for microimplant placement. Angle Orthod
80:130-136

75
Titanium alloy microimplants with small diameters (1.2-1.3 mm) are strong enough
for self-drilling and immediate loading in thin cortical bone areas, but, to reduce
the chance of breakage, a drilling of a pilot hole is suggested in thick cortical bone
areas.
Chen et al (2010). Potential of self-drilling orthodontic microimplants under immediate
loading. AJODO 137: 496–502
Microimplants with a diameter of less than 1.3 mm are unsuitable for insertion into
a bone with a density greater than 40 pounds per cubic foot mechanically when one
is using a self-drilling technique.
Chen et al (2010). Mechanical properties of self-drilling orthodontic micro-implants with
different diameters. Angle Orthod 80: 821-827
Mini-implants for orthodontic anchorage may be effectively placed in most areas
with bone density equivalent to the palatal area if they are placed from 3 mm
posterior to the incisive foramen and 1 to 5 mm to the paramedian side.
Moon et al (2010). Palatal bone density in adult subjects: implications for mini-implant
placement. Angle Orthod 80: 137-144
OMIs with larger diameters and tapered shapes caused greater microdamage to the
cortical bone; this might affect bone remodeling and the stability of the OMIs.
Lee and Baek (2010). Effects of the diameter and shape of orthodontic mini-implants on
microdamage to the cortical bone. AJODO 138: 8.e1–8.e8

Section
Five
76
To minimize root contacts, microimplants need to be inclined distally about 10° to
20° and placed 0.5 to 2.7 mm distally to the contact point to minimize root contact
according to sites and levels, except into palatal interradicular bone between the
maxillary first and second molars.
Park HS et al (2010). Proper mesiodistal angles for microimplant placement assessed
with 3-dimensional computed tomography images. AJODO 137: 200–206
Microimplant surgery seems to be a well-accepted treatment option in orthodontic
patients, with significantly lower pain levels than for tooth extractions. Furthermore,
transgingival placement is clearly favored by patients who do not need tissue
removed before placement.
Baxmann et al (2010). Expectations, acceptance, and preferences regarding microimplant
treatment in orthodontic patients: A randomized controlled trial. AJODO 138: 250.e1–250.
e10
Forallskeletalpatterns,thesafestzoneswerethespacesbetweenthesecondpremolar
and the first molar in the maxilla, and between the first and second premolars and
between the first and second molars in the mandible.
Chaimanee et al (2011). “Safe Zones” for miniscrew implant placement in different
dentoskeletal patterns. Angle Orthod 81: 397-403
Screws of diameter greater than 1.3 mm are recommended as being suitable for
resistance to fracture with self-drilling insertion.
Barros et al (2011). Effect of mini-implant diameter on fracture risk and self-drilling
efficacy. AJODO 140:e181-e192

77
Orthodontic treatment for AOB with and without miniscrew assisted intrusion of
molars: Miniscrews indeed succeeded in achieving molar intrusion and reduction in
the MMA and linear face height with very little incisor extrusion
Deguchi et al (2011). Comparison of orthodontic treatment outcomes in adults with skeletal
open bite between conventional edgewise treatment and implant-anchored orthodontics.
AJODO 139:S60-S68
With microimplant-aided sliding mechanics, clinicians can distalize all posterior
teeth together with less distal tipping. The technique seems effective and efficient to
treat patients who have mild arch length discrepancy without extractions.
Oh YH et al (2011). Treatment effects of microimplant-aided sliding mechanics on distal
retraction of posterior teeth. AJODO 139: 470–481
The differences in insertion torque values, Periotest values, and subjective
assessments of stability scores of self-drilling and self-tapping implants were
insignificant. Self-drilling implants had higher bone-implant contact percentages
than did self-tapping implants.
Çehreli and Arman-Özçırpıcı (2012). Primary stability and histomorphometric bone-
implant contact of self-drilling and self-tapping orthodontic microimplants. AJODO 141:
187–195
Modification of the mini-implant design can substantially affect the mechanical
properties. The finite element method is an effective tool to identify optimal design
parameters and allow for improved mini-implant designs.
Chang et al (2012). Effects of thread depth, taper shape, and taper length on the mechanical
propertiesofmini-implants.AJODO141:279–288

Section
Five
78
Healing of cementum takes place after an injury with a temporary skeletal anchorage
device, and it is a time-dependent phenomenon.
Ahmad V et al (2012). Root damage and repair in patients with temporary skeletal
anchorage devices. AJODO 141:547–555
Cortical bone tends to be thicker in hypodivergent than in hyperdivergent subjects.
This explains the concomitant differences in alveolar ridge thickness. Medullary
space thickness is largely unaffected by facial divergence.
Horneretal(2012).Corticalboneandridgethicknessofhyperdivergentandhypodivergent
adults.AJODO142:170–178
Both outer diameter and length affect the stability of MSIs. Increases in cortical
bone thickness and cortical bone density increase the primary stability of the MSIs.
Shah et al (2012). Effects of screw and host factors on insertion torque and pullout strength.
AngleOrthod82:603-610
In cases of thick cortical bone, predrilling might be an effective tool for reducing
microdamage without compromising OMI stability.
Cho and Baek (2012). Effects of predrilling depth and implant shape on the mechanical
properties of orthodontic mini-implants during the insertion procedure. Angle Orthod 82:
618-624

The Black Box of Orthodontic Research

The Black Box of Orthodontic Research

Recommended

Recommended

More Related Content

What's hot

What's hot (20)

Similar to The Black Box of Orthodontic Research

Similar to The Black Box of Orthodontic Research (20)

Recently uploaded

Recently uploaded (20)

The Black Box of Orthodontic Research