A to Z ORTHODONTICS Volume: 04

Dr. Mohammad Khursheed Alam BDS, PGT, PhD (Japan)

ANCHORAGE

1

First Published August 2012

Dr. Mohammad Khursheed Alam

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, electronic, mechanical, photocopying, recording or

otherwise, without prior permission of author/s or publisher.

ISBN: 978-967-5547-93-5 Correspondance:

Dr. Mohammad Khursheed Alam

Senior Lecturer

Orthodontic Unit

School of Dental Science

Health Campus, Universiti Sains Malaysia.

Email:

dralam@gmail.com

dralam@kk.usm.my

Published by:

PPSP Publication

Jabatan Pendidikan Perubatan, Pusat Pengajian Sains Perubatan,

Universiti Sains Malaysia. Kubang Kerian, 16150. Kota Bharu, Kelatan.

Published in Malaysia

2

Contents

1. Anchorage...................................................3

2. Classification..........................3-5

3. Source of anchorage.....4-7

4. Description of different types of anchorage........7-9

5. Causes of loss of anchorage.... 9

6. Means to detect anchorage loss.............................9-10

7. Means to increase anchorage value...10

8. Anchorage loss and sign........ 10-11

9. Anchorage preparation..11

3

Anchorage

Graber has defined anchorage in orthodontics as the nature and degree of

resistance to displacement offered by an anatomic unit for the purpose of

effecting tooth movement.

White & Gardener - Anchorage is the site of delivery from which a force is

exerted.

* Tooth movement during orthodontic therapy is brought about forces

generated by active component of an orthodontic appliance. The force is

used to move the teeth are derived from certain anatomic areas which act

is anchorage.

Classification:

(A) According to manner of force application:

(1) Simple anchorage.

(2) Stationary anchorage.

(3) Reciprocal anchorage.

(B) According to jaws involved:

(1) Intra maxillary.

(2) Inter maxillary.

(C) According to the site of anchorage:

4

(1) Intra oral.

(2) Extra oral A) Cervical.

(3) Muscular. B) Occipital

C) Cranial

D) Facial.

(D) According to the number of anchorage units:

(1) Single or primary anchorage.

(2) Compound anchorage.

(3) Multiple or reinforced anchorage.

(E) Depends on anchorage loss:

(1) Maximum anchorage (Type A anchorage)

A situation in which the treatment objectives require that no or very little

anchorage can be lost.

(2) Moderate anchorage (Type B anchorage)

A situation in which anchorage is not critical and space closure should be

performed by reciprocal movement of both the active and the anchorage

segment.

(3) Minimum anchorage (Type C anchorage)

5

A situation in which, for an optimal result, a considerable movement of the

anchorage segment (anchorage "loss") is desirable, during closure of

space.

Source of anchorage

During orthodontic therapy it is mainly obtained from two sources:

1. Intraoral source

2. Extraoral source

Intraoral source: The intraoral sources of anchorage include the teeth,

alveolar bone, the basal jaw bone, the musculature.

The teeth themselves can resist movement. The anchorage potential of

teeth depends on a member of factors such as root form, root size, no of

roots, root length, and root inclination.

Root form: On cross section of roots can be of three types, round, flat and

triangular.

Round roots as seen in bi cuspids and palatal root of maxillary molars can

resist horizontally directed forces in any direction.

Flat roots for an example those of mandibular incisors and molars and

buccal roots of maxillary molar can resist movements in mesio-distal

direction.

6

Triangular roots of canine and maxillary central and lateral incisor offer the

maximum resistance to displacement compared to round or flat root form.

Size and no of root: Multi rooted with large root have a greater ability to

withstand stress than single rooted teeth.

Root length: The longer the root the deeper it is embedded in bone and

the greater is its resistance to displacement.

Inclination of tooth: The greater resistance to displacement is offered

when the course exerted to move teeth is opposite to that of their axial

inclination.

Ankylosed teeth: Orthodontic movement of such teeth is not possible and

they can therefore serve as excellent anchors whenever possible.

Alveolar bone: When the force applied exceed a certain limit, the alveolar

bone permits tooth movement by bone remodeling.

Basal bone: The areas include the hard palate and the lingual surfaces of

the mandible in the region of the roots of basal bones are available

intraorally as source of anchorage.

Musculature: Muscle causes flaring and spacing of teeth. Hypertonic

muscles cause collapse of the teeth lingually.

Extraoral anchorage

7

Certain extra oral areas can also be used when adequate resistance

cannot be obtained from intra oral sources for the purpose of anchorage

.The extra oral sources of anchorage include.

1. the cranium

2. the back of the neck

3. the facial bones

Cranium (occipital / parietal anchorage)

Using head gears that derive anchorage from the occipital or parietal region

of the cranium. These devices are used along with a face bow to restrict

maxillary growth or to move the dentition or maxillary bone distally.

Back of the neck (cervical anchorage):

Extra oral anchorage can alternatively be obtained from the neck or

cervical region. Such a type of head gear is called cervical head gear,

Facial bones:

The frontal bone and the mandibles symphysis offer anchorage during face

mask therapy in order to protract the maxilla. A maxillary head gear that

makes use of anchorage from the forehead and chin are called reverse

headgears.

Description of different types of anchorage

1. Single/Simple

8

(A) Simple Anchorage: when a tooth with a longer root area is used to

move another tooth with a smaller root area in the same dental arch

(B) Compound simple: when a greater number of teeth are used to move a

smaller number of teeth in the same dental arch

2. Stationary anchorage: This is a compound anchorage where the teeth

only can move bodily to resist anchorage.

3. Reciprocal Anchorage

The anchorage is said to be reciprocal in those case where it is designed

that two teeth or low groups of teeth shall move to an equal extent towards

each other or in opposite direction.

It is necessary that each group should offer equal resistance lest, the

movement will be unequal.

Example: (1) Dental arch expunsion. [Upper expansion plate]

(2) Pin & tube appliance to approximate 1/1.

(3) Closure of midline diastema.

(4) Use of cross bite elastics.

(5) Correction of single tooth crossbite.

Intramaxillary anchorage: Anchorage obtained from a tooth/teeth in one

jaw to move the tooth/teeth in the same jaw, It may be simple (single /

compound), re-inforced or reciprocal.

9

Intermaxillary anchorage: where the teeth in one arch are used for

anchorage to move the teeth in other arch.

Causes of loss of anchorage:

1. Not wearing the appliance adequate

2. Too much activation of springs or active components

3. Presence of acrylic or any obstruction on the path of tooth movement

4. Poor retention of appliance.

5. Anterior bite plane: as this withdraws the occusal interlock,

6. Anchor root area, not sufficiently greater, then the root area of tooth or

teeth to be used,

7. If appliance encourage tipping movement of anchor teeth and bodily

movement of the teeth to be moved.

Means to detect anchorage loss

1. Position of another teeth, in relation to the teeth in the same and

opposite arch.

2. Increase in overjet.

3. Fit of the appliance in the mouth.

4. Measurements of the distance of anchor teeth from midline.

5. Measurements from palatal rugae and frenum.

10

6. Observation of the spacing mesial/distal to the anchor teeth.

7. Inclination of the anchor teeth.

8. Radiological examination.

Means to increase anchorage value:

1. Intermaxillary traction.

2. Inclined anterior bite plane.

3. Extra oral traction occipital, occipital-cervical or cervical.

4. Toe in & Tip back bends [Anchor bends for posterior anchorage] and

Apical torque [for anterior anchorage] on arch wire so that anchor teeth

can only move bodily.

5. Banding or using good number of teeth for anchorage or moving small

number of tooth at a time.

6. Use of palatal and lingual arches.

7. Use of vertical springs on anchor teeth to encourage bodily movement

only.

Anchorage loss and signs

Anchorage loss is the movement of the reaction unit or the anchor unit

instead of the teeth to be moved.

Signs:

1. Mesial movement of molars.

11

2. Closure of extraction space by movement of posterior teeth.

3. Proclination of anterior teeth.

4. Spacing of teeth.

5. Increase in overjet.

6. Change in molar relations.

7. Buccal cross bite of upper posteriors.

Anchorage preparation

A procedure commonly used in the Tweed technique, during which the

molars and premolars are tipped distally prior to retraction of the anterior

teeth. The theory behind it is that it increases the anchorage value of the

posterior segments, allowing further retraction of the canines and incisors

with less anchorage loss.

ADVANCEMENT IN ANCHORAGE

Skeletal anchorage: Micro implant / TAD / Screw implant

12

Bibilography:

1. Bhalajhi SI. Orthodontics The art and science. 4th edition. 2009

2. Gurkeerat Singh. Textbook of orthodontics. 2nd edition. Jaypee, 2007

3. Houston S and Tulley, Textbook of Orthodontics. 2nd Edition. Wright, 1992.

4. Iida J. Lecture/class notes. Professor and chairman, Dept. of Orthodontics, School of dental science, Hokkaido University, Japan.

5. Lamiya C. Lecture/class notes. Ex Associate Professor and chairman, Dept. of Orthodontics, Sapporo Dental College.

6. Laura M. An introduction to Orthodontics. 2nd edition. Oxford University Press, 2001

7. McNamara JA, Brudon, WI. Orthodontics and Dentofacial Orthopedics. 1st edition, Needham Press, Ann Arbor, MI, USA, 2001

8. Mitchel. L. An Introduction to Orthodontics. 3 editions. Oxford University Press. 2007

9. Mohammad EH. Essentials of Orthodontics for dental students. 3rd edition, 2002

10. Proffit WR, Fields HW, Sarver DM. Contemporary Orthodontics. 4th edition, Mosby Inc., St.Louis, MO, USA, 2007

11. Sarver DM, Proffit WR. In TM Graber et al., eds., Orthodontics: Current Principles and Techniques, 4th ed., St. Louis: Elsevier Mosby, 2005

12. Samir E. Bishara. Textbook of Orthodontics. Saunders 978-0721682891, 2002

13. T. M. Graber, R.L. Vanarsdall, Orthodontics, Current Principles and Techniques, "Diagnosis and Treatment Planning in Orthodontics", D. M. Sarver, W.R. Proffit, J. L. Ackerman, Mosby, 2000

14. Thomas M. Graber, Katherine W. L. Vig, Robert L. Vanarsdall Jr. Orthodontics: Current Principles and Techniques. Mosby 9780323026215, 2005

15. William R. Proffit, Raymond P. White, David M. Sarver. Contemporary treatment of dentofacial deformity. Mosby 978-0323016971, 2002

16. William R. Proffit, Henry W. Fields, and David M. Sarver. Contemporary Orthodontics. Mosby 978-0323040464, 2006

17. Yoshiaki S. Lecture/class notes. Associate Professor and chairman, Dept. of Orthodontics, School of dental science, Hokkaido University, Japan.

18. Zakir H. Lecture/class notes. Professor and chairman, Dept. of Orthodontics, Dhaka Dental College and hospital.

13

Dedicated To

My Mom, Zubaida Shaheen

My Dad, Md. Islam

&

My Only Son

Mohammad Sharjil

14

Acknowledgments I wish to acknowledge the expertise and efforts of the various teachers for their help and inspiration:

1. Prof. Iida Junichiro Chairman, Dept. of Orthodontics, Hokkaido University, Japan.

2. Asso. Prof. Sato yoshiaki Dept. of Orthodontics, Hokkaido University, Japan.

3. Asst. Prof. Kajii Takashi Dept. of Orthodontics, Hokkaido University, Japan.

4. Asst. Prof. Yamamoto Dept. of Orthodontics, Hokkaido University, Japan.

5. Asst. Prof. Kaneko Dept. of Orthodontics, Hokkaido University, Japan.

6. Asst. Prof. Kusakabe Dept. of Orthodontics, Hokkaido University, Japan.

7. Asst. Prof. Yamagata Dept. of Orthodontics, Hokkaido University, Japan.

8. Prof. Amirul Islam Principal, Bangladesh Dental college 9. Prof. Emadul Haq Principal City Dental college 10. Prof. Zakir Hossain Chairman, Dept. of Orthodontics,

Dhaka Dental College. 11. Asso. Prof. Lamiya Chowdhury Chairman, Dept. of

Orthodontics, Sapporo Dental College, Dhaka. 12. Late. Asso. Prof. Begum Rokeya Dhaka Dental College. 13. Asso. Prof. MA Sikder Chairman, Dept. of Orthodontics,

University Dental College, Dhaka. 14. Asso. Prof. Md. Saifuddin Chinu Chairman, Dept. of

Orthodontics, Pioneer Dental College, Dhaka.

15

Dr. Mohammad Khursheed Alam has obtained his PhD degree in Orthodontics from Japan in 2008. He worked as Asst. Professor and Head, Orthodontics department, Bangladesh Dental College for 3 years. At the same time he worked as consultant Orthodontist in the Dental office named Sapporo Dental square. Since then he has worked in several international projects in the field of Orthodontics. He is the author of more than 50 articles published in reputed journals. He is now working as Senior lecturer in Orthodontic unit, School of Dental Science, Universiti Sains Malaysia.

Volume of this Book has been reviewed by: Dr. Kathiravan Purmal BDS (Malaya), DGDP (UK), MFDSRCS (London), MOrth (Malaya), MOrth RCS( Edin), FRACPS. School of Dental Science, Universiti Sains Malaysia. Dr Kathiravan Purmal graduated from University Malaya 1993. He has been in private practice for almost 20 years. He is the first locally trained orthodontist in Malaysia with international qualification. He has undergone extensive training in the field of oral and maxillofacial surgery and general dentistry.