- Orthodontic tooth movement relies on efficient bone remodeling mediated by osteoblasts and osteoclasts. Pressure on the periodontal ligament causes bone resorption while tension results in bone formation, allowing tooth movement.
- Root resorption occurs microscopically with all orthodontic tooth movement but is usually repaired. Factors like fixed appliances, elastics, and root characteristics can increase the risk.
- The mechanisms of orthodontic tooth movement are still speculative but histological documentation shows bone is resorbed under pressure and formed under tension.
Optimal orthodontic force /certified fixed orthodontic courses by Indian dent...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Periodontally Accelerated Osteogenic Orthodontics (PAOO) or Wilckodontics - Rapid orthodontic treatment procedures can be achieved by performing Alveolar Corticotomies (ACS) shortly before the application of orthodontic forces.
This method has been suggested to enhance tooth movement and reduce orthodontic treatment treatment time. WICKO BROTHERS (THOMAS WILCKO AND WILLIAM WILCKO) in 2001 introduced this technique. PAOO has expanded the arena of traditional orthodontic tooth movement protocols. This technique can be especially beneficial for adult patients seeking orthodontic tooth movement.
Abstract: Corticotomy-assisted orthodontic treatment is an established and efficient orthodontic technique that has recently been studied in a number of publications. Corticotomy facilitated orthodontics have been employed in various forms over speed up orthodontic treatment It involves selective alveolar decortication in the form of decortication lines and dots performed around the teeth that are to be moved. It is done to induce a state of increased tissue turnover and a transient osteopenia, which is followed by a faster rate of orthodontic tooth movement. This technique has several advantages, including faster tooth movement, shorter treatment time, safer expansion of constricted arches, enhanced post-orthodontic treatment stability and extended envelope of tooth movement. The aim of this article is to present a comprehensive review of the literature, including historical background, contemporary clinical techniques, indications, contraindications, complications and side effects. Keywords: Corticotomy, decortication, review, orthodontic treatment
Biomechanical modifications made to accommodate orthodontic treatment of adult dentitions are generally minor and adhere to the basic laws of physics as they apply to orthodontic tooth movement.
Some adult presentations necessitate changes in treatment strategy from what would otherwise be employed in adolescent patients to achieve similar goals.
In other cases, objectives themselves may need to be modified because of lack of growth potential, constraints of treatment mandated by the patient or the presence of multiple missing or compromised teeth.
Optimal orthodontic force /certified fixed orthodontic courses by Indian dent...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Periodontally Accelerated Osteogenic Orthodontics (PAOO) or Wilckodontics - Rapid orthodontic treatment procedures can be achieved by performing Alveolar Corticotomies (ACS) shortly before the application of orthodontic forces.
This method has been suggested to enhance tooth movement and reduce orthodontic treatment treatment time. WICKO BROTHERS (THOMAS WILCKO AND WILLIAM WILCKO) in 2001 introduced this technique. PAOO has expanded the arena of traditional orthodontic tooth movement protocols. This technique can be especially beneficial for adult patients seeking orthodontic tooth movement.
Abstract: Corticotomy-assisted orthodontic treatment is an established and efficient orthodontic technique that has recently been studied in a number of publications. Corticotomy facilitated orthodontics have been employed in various forms over speed up orthodontic treatment It involves selective alveolar decortication in the form of decortication lines and dots performed around the teeth that are to be moved. It is done to induce a state of increased tissue turnover and a transient osteopenia, which is followed by a faster rate of orthodontic tooth movement. This technique has several advantages, including faster tooth movement, shorter treatment time, safer expansion of constricted arches, enhanced post-orthodontic treatment stability and extended envelope of tooth movement. The aim of this article is to present a comprehensive review of the literature, including historical background, contemporary clinical techniques, indications, contraindications, complications and side effects. Keywords: Corticotomy, decortication, review, orthodontic treatment
Biomechanical modifications made to accommodate orthodontic treatment of adult dentitions are generally minor and adhere to the basic laws of physics as they apply to orthodontic tooth movement.
Some adult presentations necessitate changes in treatment strategy from what would otherwise be employed in adolescent patients to achieve similar goals.
In other cases, objectives themselves may need to be modified because of lack of growth potential, constraints of treatment mandated by the patient or the presence of multiple missing or compromised teeth.
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Physiology of tooth movement 1 /certified fixed orthodontic courses by Indian...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
Tooth movement induced by orthodontic force application is
characterized by changes in the cells and tissue. When exposed to varying degrees of magnitude, frequency,
and duration of mechanical loading, cells and tissue show
extensive macroscopic and microscopic changes.
There are many benefits to integrating orthodontics and periodontics in the management of adult patients with underlying periodontal defects. The key to treating these patients is communication and proper diagnosis before orthodontic therapy. Not all periodontal problems are treated in the same way. It should be remembered that overall success of orthodontic treatment depends on the combined effort and close monitoring of the case, by an orthodontist and a periodontist.
Stress & force factors in implants /certified fixed orthodontic courses by I...Indian dental academy
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and offering a wide range of dental certified courses in different formats.
Indian dental academy provides dental crown & Bridge,rotary endodontics,fixed orthodontics,
Dental implants courses.for details pls visit www.indiandentalacademy.com ,or call
0091-9248678078
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
The Indian Dental Academy is the Leader in continuing dental education , training dentists in all aspects of dentistry and
offering a wide range of dental certified courses in different formats.for more details please visit
www.indiandentalacademy.com
Ozempic: Preoperative Management of Patients on GLP-1 Receptor Agonists Saeid Safari
Preoperative Management of Patients on GLP-1 Receptor Agonists like Ozempic and Semiglutide
ASA GUIDELINE
NYSORA Guideline
2 Case Reports of Gastric Ultrasound
ABDOMINAL TRAUMA in pediatrics part one.drhasanrajab
Abdominal trauma in pediatrics refers to injuries or damage to the abdominal organs in children. It can occur due to various causes such as falls, motor vehicle accidents, sports-related injuries, and physical abuse. Children are more vulnerable to abdominal trauma due to their unique anatomical and physiological characteristics. Signs and symptoms include abdominal pain, tenderness, distension, vomiting, and signs of shock. Diagnosis involves physical examination, imaging studies, and laboratory tests. Management depends on the severity and may involve conservative treatment or surgical intervention. Prevention is crucial in reducing the incidence of abdominal trauma in children.
NVBDCP.pptx Nation vector borne disease control programSapna Thakur
NVBDCP was launched in 2003-2004 . Vector-Borne Disease: Disease that results from an infection transmitted to humans and other animals by blood-feeding arthropods, such as mosquitoes, ticks, and fleas. Examples of vector-borne diseases include Dengue fever, West Nile Virus, Lyme disease, and malaria.
Title: Sense of Smell
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the primary categories of smells and the concept of odor blindness.
Explain the structure and location of the olfactory membrane and mucosa, including the types and roles of cells involved in olfaction.
Describe the pathway and mechanisms of olfactory signal transmission from the olfactory receptors to the brain.
Illustrate the biochemical cascade triggered by odorant binding to olfactory receptors, including the role of G-proteins and second messengers in generating an action potential.
Identify different types of olfactory disorders such as anosmia, hyposmia, hyperosmia, and dysosmia, including their potential causes.
Key Topics:
Olfactory Genes:
3% of the human genome accounts for olfactory genes.
400 genes for odorant receptors.
Olfactory Membrane:
Located in the superior part of the nasal cavity.
Medially: Folds downward along the superior septum.
Laterally: Folds over the superior turbinate and upper surface of the middle turbinate.
Total surface area: 5-10 square centimeters.
Olfactory Mucosa:
Olfactory Cells: Bipolar nerve cells derived from the CNS (100 million), with 4-25 olfactory cilia per cell.
Sustentacular Cells: Produce mucus and maintain ionic and molecular environment.
Basal Cells: Replace worn-out olfactory cells with an average lifespan of 1-2 months.
Bowman’s Gland: Secretes mucus.
Stimulation of Olfactory Cells:
Odorant dissolves in mucus and attaches to receptors on olfactory cilia.
Involves a cascade effect through G-proteins and second messengers, leading to depolarization and action potential generation in the olfactory nerve.
Quality of a Good Odorant:
Small (3-20 Carbon atoms), volatile, water-soluble, and lipid-soluble.
Facilitated by odorant-binding proteins in mucus.
Membrane Potential and Action Potential:
Resting membrane potential: -55mV.
Action potential frequency in the olfactory nerve increases with odorant strength.
Adaptation Towards the Sense of Smell:
Rapid adaptation within the first second, with further slow adaptation.
Psychological adaptation greater than receptor adaptation, involving feedback inhibition from the central nervous system.
Primary Sensations of Smell:
Camphoraceous, Musky, Floral, Pepperminty, Ethereal, Pungent, Putrid.
Odor Detection Threshold:
Examples: Hydrogen sulfide (0.0005 ppm), Methyl-mercaptan (0.002 ppm).
Some toxic substances are odorless at lethal concentrations.
Characteristics of Smell:
Odor blindness for single substances due to lack of appropriate receptor protein.
Behavioral and emotional influences of smell.
Transmission of Olfactory Signals:
From olfactory cells to glomeruli in the olfactory bulb, involving lateral inhibition.
Primitive, less old, and new olfactory systems with different path
Knee anatomy and clinical tests 2024.pdfvimalpl1234
This includes all relevant anatomy and clinical tests compiled from standard textbooks, Campbell,netter etc..It is comprehensive and best suited for orthopaedicians and orthopaedic residents.
- Video recording of this lecture in English language: https://youtu.be/kqbnxVAZs-0
- Video recording of this lecture in Arabic language: https://youtu.be/SINlygW1Mpc
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
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Rasamanikya is a excellent preparation in the field of Rasashastra, it is used in various Kushtha Roga, Shwasa, Vicharchika, Bhagandara, Vatarakta, and Phiranga Roga. In this article Preparation& Comparative analytical profile for both Formulationon i.e Rasamanikya prepared by Kushmanda swarasa & Churnodhaka Shodita Haratala. The study aims to provide insights into the comparative efficacy and analytical aspects of these formulations for enhanced therapeutic outcomes.
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Adv. biopharm. APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMSAkankshaAshtankar
MIP 201T & MPH 202T
ADVANCED BIOPHARMACEUTICS & PHARMACOKINETICS : UNIT 5
APPLICATION OF PHARMACOKINETICS : TARGETED DRUG DELIVERY SYSTEMS By - AKANKSHA ASHTANKAR
Title: Sense of Taste
Presenter: Dr. Faiza, Assistant Professor of Physiology
Qualifications:
MBBS (Best Graduate, AIMC Lahore)
FCPS Physiology
ICMT, CHPE, DHPE (STMU)
MPH (GC University, Faisalabad)
MBA (Virtual University of Pakistan)
Learning Objectives:
Describe the structure and function of taste buds.
Describe the relationship between the taste threshold and taste index of common substances.
Explain the chemical basis and signal transduction of taste perception for each type of primary taste sensation.
Recognize different abnormalities of taste perception and their causes.
Key Topics:
Significance of Taste Sensation:
Differentiation between pleasant and harmful food
Influence on behavior
Selection of food based on metabolic needs
Receptors of Taste:
Taste buds on the tongue
Influence of sense of smell, texture of food, and pain stimulation (e.g., by pepper)
Primary and Secondary Taste Sensations:
Primary taste sensations: Sweet, Sour, Salty, Bitter, Umami
Chemical basis and signal transduction mechanisms for each taste
Taste Threshold and Index:
Taste threshold values for Sweet (sucrose), Salty (NaCl), Sour (HCl), and Bitter (Quinine)
Taste index relationship: Inversely proportional to taste threshold
Taste Blindness:
Inability to taste certain substances, particularly thiourea compounds
Example: Phenylthiocarbamide
Structure and Function of Taste Buds:
Composition: Epithelial cells, Sustentacular/Supporting cells, Taste cells, Basal cells
Features: Taste pores, Taste hairs/microvilli, and Taste nerve fibers
Location of Taste Buds:
Found in papillae of the tongue (Fungiform, Circumvallate, Foliate)
Also present on the palate, tonsillar pillars, epiglottis, and proximal esophagus
Mechanism of Taste Stimulation:
Interaction of taste substances with receptors on microvilli
Signal transduction pathways for Umami, Sweet, Bitter, Sour, and Salty tastes
Taste Sensitivity and Adaptation:
Decrease in sensitivity with age
Rapid adaptation of taste sensation
Role of Saliva in Taste:
Dissolution of tastants to reach receptors
Washing away the stimulus
Taste Preferences and Aversions:
Mechanisms behind taste preference and aversion
Influence of receptors and neural pathways
Impact of Sensory Nerve Damage:
Degeneration of taste buds if the sensory nerve fiber is cut
Abnormalities of Taste Detection:
Conditions: Ageusia, Hypogeusia, Dysgeusia (parageusia)
Causes: Nerve damage, neurological disorders, infections, poor oral hygiene, adverse drug effects, deficiencies, aging, tobacco use, altered neurotransmitter levels
Neurotransmitters and Taste Threshold:
Effects of serotonin (5-HT) and norepinephrine (NE) on taste sensitivity
Supertasters:
25% of the population with heightened sensitivity to taste, especially bitterness
Increased number of fungiform papillae
Recomendações da OMS sobre cuidados maternos e neonatais para uma experiência pós-natal positiva.
Em consonância com os ODS – Objetivos do Desenvolvimento Sustentável e a Estratégia Global para a Saúde das Mulheres, Crianças e Adolescentes, e aplicando uma abordagem baseada nos direitos humanos, os esforços de cuidados pós-natais devem expandir-se para além da cobertura e da simples sobrevivência, de modo a incluir cuidados de qualidade.
Estas diretrizes visam melhorar a qualidade dos cuidados pós-natais essenciais e de rotina prestados às mulheres e aos recém-nascidos, com o objetivo final de melhorar a saúde e o bem-estar materno e neonatal.
Uma “experiência pós-natal positiva” é um resultado importante para todas as mulheres que dão à luz e para os seus recém-nascidos, estabelecendo as bases para a melhoria da saúde e do bem-estar a curto e longo prazo. Uma experiência pós-natal positiva é definida como aquela em que as mulheres, pessoas que gestam, os recém-nascidos, os casais, os pais, os cuidadores e as famílias recebem informação consistente, garantia e apoio de profissionais de saúde motivados; e onde um sistema de saúde flexível e com recursos reconheça as necessidades das mulheres e dos bebês e respeite o seu contexto cultural.
Estas diretrizes consolidadas apresentam algumas recomendações novas e já bem fundamentadas sobre cuidados pós-natais de rotina para mulheres e neonatos que recebem cuidados no pós-parto em unidades de saúde ou na comunidade, independentemente dos recursos disponíveis.
É fornecido um conjunto abrangente de recomendações para cuidados durante o período puerperal, com ênfase nos cuidados essenciais que todas as mulheres e recém-nascidos devem receber, e com a devida atenção à qualidade dos cuidados; isto é, a entrega e a experiência do cuidado recebido. Estas diretrizes atualizam e ampliam as recomendações da OMS de 2014 sobre cuidados pós-natais da mãe e do recém-nascido e complementam as atuais diretrizes da OMS sobre a gestão de complicações pós-natais.
O estabelecimento da amamentação e o manejo das principais intercorrências é contemplada.
Recomendamos muito.
Vamos discutir essas recomendações no nosso curso de pós-graduação em Aleitamento no Instituto Ciclos.
Esta publicação só está disponível em inglês até o momento.
Prof. Marcus Renato de Carvalho
www.agostodourado.com
2. PRACTICE
392 BRITISH DENTAL JOURNAL VOLUME 196 NO. 7 APRIL 10 2004
increase in ionised blood calcium within
1 hour. These finding have done much to
unravel the final links between bone forma-
tion and resorption.
One other role that osteoblasts have in bone
resorption is removal of the non-mineralised
osteoid layer. In response to bone resorbing hor-
mones, the osteoblast secretes MMPs which are
responsible for removal of osteoid. This exposes
the mineral layer to osteoclasts for resorption. It
has been suggested that the mineral is also
chemotactic for osteoclast recruitment and
function.
How mechanical forces stimulate bone
remodelling remains a mystery but some key
facts are known. First, intermittent forces
stimulate more bone remodelling than contin-
uous forces. It is likely that during orthodontic
tooth movement intermittent forces are gener-
ated because of ‘jiggling’ effects as teeth come
into occlusal contact. Second, the key regula-
tory cell in bone metabolism is the osteoblast.
It is therefore relevant to examine what effects
mechanical forces have on these cells. The
application of a force to a cell membrane trig-
gers off a number of responses inside the cell
and this is usually mediated by second mes-
sengers. It is known that cyclic AMP, inositol
phosphates and intracellular calcium are all
elevated by mechanical forces. Indeed the
entry of calcium to the cell may come from
G-protein controlled ion channels or release
of calcium from internal cellular stores. These
messengers will evoke a nuclear response
which will either result in production of fac-
tors responsible for osteoclast recruitment and
activation, or bone forming growth factors.
An indirect pathway of activation also exists
whereby membrane enzymes (phospholipase
A2) make substrate (arachidonic acid) avail-
able for the generation of prostaglandins and
leukotrienes. These compounds have both
been implicated in tooth movement.
The main theories of tooth movement are
now summarised:
BIOMECHANCIAL ORTHODONTIC TOOTH
MOVEMENT
This theory simply states that mechanically dis-
torting a cell membrane activates PLA2 making
arachidonic acid available for the action of cyclo
and lipoxygenase enzymes. This produces
prostaglandins which feed back onto the cell
membrane binding to receptors which then
stimulate second messengers and elicit a cell
response. Ultimately, these responses will
include bone being laid down in tension sites
and bone being resorbed at pressure sites. It is
not clear how tissues discriminate between ten-
sion and pressure. It is worth remembering that
cells which are rounded up show catabolic
changes whereas flattened cells (? under tension)
have anabolic effects.
BONE BENDING, PIEZOELECTRIC AND
MAGNETIC FORCES
There was considerable interest in piezoelectricity
as a stimulus for bone remodelling during the
1960s. This arose because it was noted that distor-
tion of crystalline structures generated small elec-
trical charges, which potentially may have been
responsible for signalling bone changes associat-
ed with mechanical forces. The interest therefore
in ‘electricity’ and bone was considerable.
Magnets have been used to provide the force
needed for orthodontic tooth movement. Classi-
cally an unerupted tooth has a magnet attached
to it and a second magnet is placed on an ortho-
dontic appliance with the poles orientated to
provide an attractive force. It is unlikely that the
magnetic forces alone have any actions on tis-
sues. If magnetic fields are broken (as in pulsed
electromagnetic fields) then there is some evi-
dence that tissues will respond. It is worth mak-
ing the following points about the effects of
magnetic and electric fields on tooth movement:
• The periodontal ligament is unlikely to trans-
fer forces to bone. If the periodontal ligament
is disrupted, orthodontic tooth movement still
occurs
Intermittent forces
appear to move teeth
and stimulate bone
remodelling more
efficiently than
continuous forces
Fig. 1 Pressure side of a tooth being moved. The very vascular
periodontal ligament has cementum on one side and bone on the
other where frontal resorption is occurring. Osteoclasts can be seen
in their lacunae resorbing bone on it's ‘frontal edge’
Fig. 2 This is a tension site where the bone adjacent to the
periodontal ligament has surface lining osteoblasts and no sign of
any osteoclasts. New bone is laid down as the tooth moves
07p391-394.qxd 09/03/2004 16:56 Page 392
3. PRACTICE
BRITISH DENTAL JOURNAL VOLUME 196 NO. 7 APRIL 10 2004 393
• Magnetic fields alone have little, if any, effect
on tissues
• Pulsed magnetic fields (which induce electric
fields) can increase the rate and amount of
tooth movement
• When an orthodontic force is applied, the
tooth is displaced many times more than the
periodontal ligament width. Bone bending
must therefore occur in order to account for
the tooth movement over and above the width
of the periodontal ligament
• Physically distorting dry bone produces
piezoelectric forces which have been implicat-
ed in tooth movement. Piezoelectric forces are
those charges which develop as a consequence
of distorting any crystalline structure. The
magnitude of the charges is very small and
there is some doubt whether they are suffi-
cient to induce cellular change.
• It must also be remembered that in hydrated
tissues, streaming potential and nerve impuls-
es produce larger electrical fields and thus it is
unlikely that piezoelectric forces alone are
responsible for tooth movement.2
A wider application of the phenomenon of
mechanically induced bone remodelling is
seen where sutures are stretched. In young
orthodontic patients the midline palatal
suture can be split using rapid maxillary
expansion techniques. The resulting tension
generates new bone which fills in between the
distracted maxillary shelves. A similar tech-
nique is also used to lengthen limbs. This
method, known as distraction osteogenesis,
can be used in any situation where it is hoped
that new bone will be generated. Originally
this was described in Russia where many sol-
diers returning from war faced the problem of
non-union limb fractures. Initially attempts
were made to induce new bone formation by
compressing bone ends. It was only when a
patient inadvertently turned the screw for
compression of bone ends in the wrong direc-
tion that it was noted excessive new bone for-
mation was seen where bone ends were dis-
tracted rather than compressed.
This may also have application in patients
whose sutures fuse prematurely (craniosynos-
toses such as Crouzon's or Aperts Syndrome).
In this situation continued growth of the brain
results in a characteristic appearance of the
cranium but more importantly the eyes
become protuberant with possible damage to
the optic nerve. Treatment involves surgically
opening the prematurely fused sutures and
burring out to enable normal brain growth. If
distraction forces are applied prior to this early
fusion then bony infill could occur at a con-
trolled rate. The phenomenon of pressure
resulting in bone loss is also seen in pathologi-
cal lesions. Much work was done to examine
pressures within cystic lesions and to equate
this with the rate of bone destruction. It is now
recognised that cytokines and bone resorbing
factors produced by cystic and malignant
lesions are more likely to be responsible for the
associated bone resorption.
Tension results in
bone formation, this
can be used to
generate new bone
for digit lengthening
or suture distraction
Fig. 3 This is an area of excessive pressure
where the periodontal ligament has been
crushed or ‘hylanized’ and the periodontal
ligament has lost its structure. There is a large
cell lying in a lacunae behind the frontal edge
which is probably an area of undermining
resorption
Fig. 4 Area of root resorption associated with
orthodontic tooth movement. The apex of
the tooth has a large excavation of the root
surface and this is typical of excessive
tipping forces that are placed on the apices
of the teeth
07p391-394.qxd 09/03/2004 16:58 Page 393
4. PRACTICE
394 BRITISH DENTAL JOURNAL VOLUME 196 NO. 7 APRIL 10 2004
ROOT RESORPTION
The ability to move teeth through bone is
dependent on bone being resorbed and tooth
roots remaining intact. It is highly probable that
all teeth which have undergone orthodontic
tooth movement exhibit some degree of micro-
scopic root resorption (Fig. 4). Excessive root
resorption is found in 3–5% of orthodontic
patients. Some teeth are more susceptible than
others, upper lateral incisors can, on average,
lose 2 mm of root length during a course of fixed
orthodontic treatment. There are specific fea-
tures of appliances which can increase the risk of
root resorption. The following are considered
risk factors:
• Fixed appliances
• Class II elastics
• Rectangular wires
• Orthognathic surgery
There is also some evidence that the use of
functional appliances appears to cause less
resorption than fixed appliances and may be
used to reduce increased overjet where there are
recognised risks of root resorption which include
pre-existing features such as:
• Short roots
• Blunt root apices
• Thin conical roots
• Root filled teeth
• Teeth which have been previously traumatised
What prevents roots from resorbing is not
known but the following have been suggested:
• Cementum has anti-angiogenic properties.
This means blood vessels are inhibited from
forming adjacent to cementum and osteo-
clasts have less access for resorption.
• Periodontal ligament fibres are inserted more
densely in cementum than alveolar bone and
thus osteoclasts have less access to the cemen-
tal layer.
• Cementum is harder than bone and more
densely mineralised.
• Cemental repair may be by a material which is
intermediate between bone and cementum.
These semi-bone like cells may be more
responsive to systemic factors such as parathy-
roid hormone and thus where roots are already
short (and repaired with a bone/cementum like
material) the teeth are more susceptible to fur-
ther root resorption.
The exact reason why roots generally do not
resorb is not known but without this property it
would not be possible to move teeth orthodonti-
cally. A number of reviews are available which
cover bone remodelling and tooth movement in
greater depth.3,4
1. Waddington R J, Embery G, Samuels R H. Characterization of
proteoglycan metabolites in human gingival fluid during
orthodontic tooth movement. ArchOralBiol1994; 39: 361-
368.
2. McDonald F. Electrical effects at the bone surface. EurJ
Orthod1993; 15: 175-183.
3. Hill P A. Bone remodelling. BrJOrthod 1998; 25: 101-107.
4. Sandy J R, Farndale R W, Meikle M C. Recent advances in
understanding mechanically-induced bone remodelling and
their relevance to orthodontic theory and practice.AmJ
OrthodDento-facOrthop1993; 103: 212-222.
The British Dental Association Research Foundation
invites applications for awards from the Shirley Glasstone
Hughes Memorial Prize Fund.
The Prize may be awarded as a single three year project
grant commencing in 2004, to a maximum of £16,000
including all salary ‘on costs' and running expenses.
Alternatively, smaller grants may be made to more
projects, to the same total. Applications will be
considered from dentists in all fields of practice.
Where applications are made by dentists who are not
in university employment, the Foundation advises that
applications should include appropriate supervisory
arrangements involving an independent experienced
researcher.
The Foundation will favour projects, which will yield
results of direct clinical relevance.
Shirley Glasstone Hughes Memorial Prize for Dental Research
Application forms
and further
information are
available from:
BDA Awards Officer,
Members’ Services
Department
British Dental
Association,
64 Wimpole Street,
London W1G 8YS
Tel: 020 7563 4174
Email: awards@bda.org
The closing date for applications is Friday 30th April 2004.
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