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
Corrective orthodontics- deep bite & open biteDrSusmita Shah
Management of deep bite and open bite (anterior, posterior) has been covered in this presentation. Removable as well as fixed corrective orthodontic treatment options have been mentioned.
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
Corrective orthodontics- deep bite & open biteDrSusmita Shah
Management of deep bite and open bite (anterior, posterior) has been covered in this presentation. Removable as well as fixed corrective orthodontic treatment options have been mentioned.
Orthodontic diagnosis deals with recognition of the various characteristics of the malocclusion. It involves collection of pertinent data in a systemic manner to help in the identifying the nature and cause of the problem.
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
Molar uprighting /certified fixed orthodontic courses by Indian dental academy 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
Management of Crowding /certified fixed orthodontic courses by Indian dental...Indian dental academy
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.
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
Management of Deepbite /certified fixed orthodontic courses by Indian dental ...Indian dental academy
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.
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
Orthodontic diagnosis deals with recognition of the various characteristics of the malocclusion. It involves collection of pertinent data in a systemic manner to help in the identifying the nature and cause of the problem.
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
Molar uprighting /certified fixed orthodontic courses by Indian dental academy 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
Management of Crowding /certified fixed orthodontic courses by Indian dental...Indian dental academy
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.
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
Management of Deepbite /certified fixed orthodontic courses by Indian dental ...Indian dental academy
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.
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
Arch Form in orthodontics /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
Inheritance and malocclusion / /certified fixed orthodontic courses by India...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
00919248678078
Hybrid vigor in plants, and the role of epigenetics.Colin Rijkenberg
In the present report we address the role of epigenetics in the phenomenon of hybrid vigor in plants, and aim to provide a clear and thorough overview of the recent findings on epigenetic dynamics in plant hybrids and allopolyploids, the mechanisms involved, and their potential contribution to heterosis.
Life-Span Human Development 9th Edition Sigelman Solutions ManualTimothyPadilla
Full download : https://alibabadownload.com/product/life-span-human-development-9th-edition-sigelman-solutions-manual/
Life-Span Human Development 9th Edition Sigelman Solutions Manual
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
SOMEONE HELP Complete sentences, stating the differences and relati.pdfexpressionnoveltiesk
SOMEONE HELP: Complete sentences, stating the differences and relationships between the
two terms, and give specific examples where appropriate.
1. gene flow / genetic drift
2. sexual selection / artificial selection
3. ring species / biological species concept
4. hybrid inviability / temporal isolation
5. autopolyploidy / allopatric speciation
6. molecular clock / cladogram
7. gradualism / uniformitarianism
8. extreme thermophiles / viroids
9. HIV / Creutzfeld-Jakob disease
10. biofilm / microbial fuel cell
Solution
Q.No 1
Genetic drift is a mechanism of evolution of biological species that takes place because of the
change in the frequency of alleles in a population. These changes in the allele frequency in a
population occur randomly. One very common example to describe the genetic drift would be
that most of the human families have different number of boys and girls, as the X or Y alleles
have been passed differently into the new generation from the parents. Although the X and Y
alleles do not really contribute for the evolution, the frequency changes in other alleles would
have a considerable effect for evolution.
Gene flow is a process of evolution that takes place when genes or alleles move from one
population to another. It is also known as the Gene Migration, and that could cause changes in
the allele frequency as well as some variations in the gene pool of both populations. There are
some good examples to support this phenomenon from humans regarding a developed immunity
for malaria among new Western Africans after their parents mated with Europeans who initially
had the immunity. It is interesting to notice that gene flow could take place between two species,
as well.
Q.No 2
Sexual selection enhances mating success or the number of copulations, while natural selection
tends to produce well-adapted individuals to their environment. Sexual selection does not adapt
the individuals to their environment. Unlike sexual selection, natural selection acts on traits
which increase the fitness of members in a population. Certain adaptations have been derived
from the sexual selection which could never have been arisen from natural selection alone (Ex:
the neck of the giraffe, various plumages of most male birds etc.). Generally sexual selection
depends on the success of one sex while natural selection depends on the success of both sexes in
relation to the general condition of life. In most of the animals, certain traits related to their
sexual selection process do not express their characteristics until the organism is able to mate,
but naturally selected traits may occur at birth of the organism during the process of natural
selection.
Q.No 3
A ring species is a connected series of neighbouring populations, each of which can interbreed
with closely sited related populations, but for which there exist at least two \"end\" populations in
the series, which are too distantly related to interbreed, though there is a potential gene flow
between e.
The multifactorial factors influenc cleft Lip-literature review Abu-Hussein Muhamad
Congenital cleft-Lip and cleft palate have been the subject of many genetic
studies, but until recently there has been no consensus as to their modes of
inheritance. In fact, claims have been made for just about every genetic
mechanism one can think of. Recently, however, evidence has been
accumulating that favors a multifactorial basis for these malformations. The
purpose of the present paper is to present the etiology of cleft lip and cleft palate
both the genetic and the environmental factors. It is suggested that the genetic
basis for diverse kinds of common or uncommon congenital malformations may
very well be homogeneous, whilst, at the same, the environmental basis is
heterogeneous.
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
Description :
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
Essays On Cancer. Cancer essays - Reliable Essay Writers That Deserve Your TrustKimberly Jabbour
Breast Cancer Information Essay Free Essay Example. Top Cancer Essay Thatsnotus. Essay on cancer pathogenesis and the 6 hallmarks of cancer PHU3111 .... cancer essay. Cancer Writing Assignment Cancer Earth amp; Life Sciences. Cancer in College Students, Essay Sample SpeedyPaper.com. Understanding Breast Cancer - Free Essay Example PapersOwl.com. Environmental Factors that Could Cause Cancer Essay Example Topics .... essay examples: Breast Cancer Essay. Introduction Cancer Today: Origins, Prevention, and Treatment The .... Inflammatory Breast Cancer Essay Example Topics and Well Written .... The dust bowl essay - Trustworthy Writing Service From Top Professionals. How the American Cancer Society Might Provide Education and Support .... Essay on Cancer Cancer Essay for Students and Children in English - A .... The Origin and Treatment of Cancer Essay Example Topics and Well .... Breast cancer college essays. Cancer essays - reportz515.web.fc2.com. Cancer. Approach for Cancer Care Essay Example Topics and Well Written Essays .... Imposing Breast Cancer Essay Thatsnotus. Topic C - Cancer Essay - Cancer is among the worlds deadliest .... Chemotherapy essay Chemotherapy Cancer. Thesis for cancer research paper. 012 Free Breast Cancer Essays Essay About Dreams Thatsnotus. Skin cancer research paper conclusion / custom essay paper writing. Scholarship essay: Cancer essay. Essay on cancer disease. Essay on Introduction and Conclusion to .... Write an essay about cancer. Essay: Cancer. 2019-01-21. Pin on cancer prevention. Cancer essays - Reliable Essay Writers That Deserve Your Trust Essays On Cancer Essays On Cancer. Cancer essays - Reliable Essay Writers That Deserve Your Trust
Similar to Aetiology of malocclusion / for orthodontists by Almuzian (20)
Tom Selleck Health: A Comprehensive Look at the Iconic Actor’s Wellness Journeygreendigital
Tom Selleck, an enduring figure in Hollywood. has captivated audiences for decades with his rugged charm, iconic moustache. and memorable roles in television and film. From his breakout role as Thomas Magnum in Magnum P.I. to his current portrayal of Frank Reagan in Blue Bloods. Selleck's career has spanned over 50 years. But beyond his professional achievements. fans have often been curious about Tom Selleck Health. especially as he has aged in the public eye.
Follow us on: Pinterest
Introduction
Many have been interested in Tom Selleck health. not only because of his enduring presence on screen but also because of the challenges. and lifestyle choices he has faced and made over the years. This article delves into the various aspects of Tom Selleck health. exploring his fitness regimen, diet, mental health. and the challenges he has encountered as he ages. We'll look at how he maintains his well-being. the health issues he has faced, and his approach to ageing .
Early Life and Career
Childhood and Athletic Beginnings
Tom Selleck was born on January 29, 1945, in Detroit, Michigan, and grew up in Sherman Oaks, California. From an early age, he was involved in sports, particularly basketball. which played a significant role in his physical development. His athletic pursuits continued into college. where he attended the University of Southern California (USC) on a basketball scholarship. This early involvement in sports laid a strong foundation for his physical health and disciplined lifestyle.
Transition to Acting
Selleck's transition from an athlete to an actor came with its physical demands. His first significant role in "Magnum P.I." required him to perform various stunts and maintain a fit appearance. This role, which he played from 1980 to 1988. necessitated a rigorous fitness routine to meet the show's demands. setting the stage for his long-term commitment to health and wellness.
Fitness Regimen
Workout Routine
Tom Selleck health and fitness regimen has evolved. adapting to his changing roles and age. During his "Magnum, P.I." days. Selleck's workouts were intense and focused on building and maintaining muscle mass. His routine included weightlifting, cardiovascular exercises. and specific training for the stunts he performed on the show.
Selleck adjusted his fitness routine as he aged to suit his body's needs. Today, his workouts focus on maintaining flexibility, strength, and cardiovascular health. He incorporates low-impact exercises such as swimming, walking, and light weightlifting. This balanced approach helps him stay fit without putting undue strain on his joints and muscles.
Importance of Flexibility and Mobility
In recent years, Selleck has emphasized the importance of flexibility and mobility in his fitness regimen. Understanding the natural decline in muscle mass and joint flexibility with age. he includes stretching and yoga in his routine. These practices help prevent injuries, improve posture, and maintain mobilit
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
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
- Video recording of this lecture in English language: https://youtu.be/lK81BzxMqdo
- Video recording of this lecture in Arabic language: https://youtu.be/Ve4P0COk9OI
- Link to download the book free: https://nephrotube.blogspot.com/p/nephrotube-nephrology-books.html
- Link to NephroTube website: www.NephroTube.com
- Link to NephroTube social media accounts: https://nephrotube.blogspot.com/p/join-nephrotube-on-social-media.html
New Directions in Targeted Therapeutic Approaches for Older Adults With Mantl...i3 Health
i3 Health is pleased to make the speaker slides from this activity available for use as a non-accredited self-study or teaching resource.
This slide deck presented by Dr. Kami Maddocks, Professor-Clinical in the Division of Hematology and
Associate Division Director for Ambulatory Operations
The Ohio State University Comprehensive Cancer Center, will provide insight into new directions in targeted therapeutic approaches for older adults with mantle cell lymphoma.
STATEMENT OF NEED
Mantle cell lymphoma (MCL) is a rare, aggressive B-cell non-Hodgkin lymphoma (NHL) accounting for 5% to 7% of all lymphomas. Its prognosis ranges from indolent disease that does not require treatment for years to very aggressive disease, which is associated with poor survival (Silkenstedt et al, 2021). Typically, MCL is diagnosed at advanced stage and in older patients who cannot tolerate intensive therapy (NCCN, 2022). Although recent advances have slightly increased remission rates, recurrence and relapse remain very common, leading to a median overall survival between 3 and 6 years (LLS, 2021). Though there are several effective options, progress is still needed towards establishing an accepted frontline approach for MCL (Castellino et al, 2022). Treatment selection and management of MCL are complicated by the heterogeneity of prognosis, advanced age and comorbidities of patients, and lack of an established standard approach for treatment, making it vital that clinicians be familiar with the latest research and advances in this area. In this activity chaired by Michael Wang, MD, Professor in the Department of Lymphoma & Myeloma at MD Anderson Cancer Center, expert faculty will discuss prognostic factors informing treatment, the promising results of recent trials in new therapeutic approaches, and the implications of treatment resistance in therapeutic selection for MCL.
Target Audience
Hematology/oncology fellows, attending faculty, and other health care professionals involved in the treatment of patients with mantle cell lymphoma (MCL).
Learning Objectives
1.) Identify clinical and biological prognostic factors that can guide treatment decision making for older adults with MCL
2.) Evaluate emerging data on targeted therapeutic approaches for treatment-naive and relapsed/refractory MCL and their applicability to older adults
3.) Assess mechanisms of resistance to targeted therapies for MCL and their implications for treatment selection
These simplified slides by Dr. Sidra Arshad present an overview of the non-respiratory functions of the respiratory tract.
Learning objectives:
1. Enlist the non-respiratory functions of the respiratory tract
2. Briefly explain how these functions are carried out
3. Discuss the significance of dead space
4. Differentiate between minute ventilation and alveolar ventilation
5. Describe the cough and sneeze reflexes
Study Resources:
1. Chapter 39, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 34, Ganong’s Review of Medical Physiology, 26th edition
3. Chapter 17, Human Physiology by Lauralee Sherwood, 9th edition
4. Non-respiratory functions of the lungs https://academic.oup.com/bjaed/article/13/3/98/278874
Ethanol (CH3CH2OH), or beverage alcohol, is a two-carbon alcohol
that is rapidly distributed in the body and brain. Ethanol alters many
neurochemical systems and has rewarding and addictive properties. It
is the oldest recreational drug and likely contributes to more morbidity,
mortality, and public health costs than all illicit drugs combined. The
5th edition of the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5) integrates alcohol abuse and alcohol dependence into a single
disorder called alcohol use disorder (AUD), with mild, moderate,
and severe subclassifications (American Psychiatric Association, 2013).
In the DSM-5, all types of substance abuse and dependence have been
combined into a single substance use disorder (SUD) on a continuum
from mild to severe. A diagnosis of AUD requires that at least two of
the 11 DSM-5 behaviors be present within a 12-month period (mild
AUD: 2–3 criteria; moderate AUD: 4–5 criteria; severe AUD: 6–11 criteria).
The four main behavioral effects of AUD are impaired control over
drinking, negative social consequences, risky use, and altered physiological
effects (tolerance, withdrawal). This chapter presents an overview
of the prevalence and harmful consequences of AUD in the U.S.,
the systemic nature of the disease, neurocircuitry and stages of AUD,
comorbidities, fetal alcohol spectrum disorders, genetic risk factors, and
pharmacotherapies for AUD.
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.
ARTIFICIAL INTELLIGENCE IN HEALTHCARE.pdfAnujkumaranit
Artificial intelligence (AI) refers to the simulation of human intelligence processes by machines, especially computer systems. It encompasses tasks such as learning, reasoning, problem-solving, perception, and language understanding. AI technologies are revolutionizing various fields, from healthcare to finance, by enabling machines to perform tasks that typically require human intelligence.
Aetiology of malocclusion / for orthodontists by Almuzian
1. Mohammed Almuzian, University of Glasgow, 2013 Page 1
UNIVERSITY OF GLASGOW
Aetiology of malocclusion
Personal notes
Mohammed Almuzian
2013
2. Mohammed Almuzian, University of Glasgow, 2013 Page 2
Contents
Definition.................................................................................................................................4
History.....................................................................................................................................4
Prevalence................................................................................................................................ 4
The etiological factors .............................................................................................................. 5
Certain terms in genetics ...........................................................................................................6
Evidences of genetic roles in development of malocclusion: ........................................................ 6
Environmental factors ............................................................................................................... 8
Modern theory of the environment influence on malocclusion...................................................... 9
Epi-Genetic Theory................................................................................................................... 9
Soft tissues theory................................................................................................................... 10
Developmental pathology influencing facial development ......................................................... 10
Postnatal factors..................................................................................................................... 11
Physiological soft tissue factors (see soft tissue factors)............................................................. 12
Soft tissue factors.................................................................................................................... 12
Introduction............................................................................................................................ 12
Soft tissue factors.................................................................................................................... 12
Muscles of facial expression, Sandy 1997................................................................................. 13
Lips at rest (Position, lip line & competence)........................................................................... 13
Skeletal AP & vertical relationship as determinant factors for lip position, line and competency.
Three examples of patients with different skeletal discrepancies: ............................................... 13
Lips at function....................................................................................................................... 13
Tongue at rest......................................................................................................................... 15
Tongue in function.................................................................................................................. 15
Muscle of mastication ............................................................................................................. 16
Adenoid & Soft tissues stretching ............................................................................................ 16
Methods of Measuring Airflow (Rhinomanometry) ......................... Error! Bookmark not defined.
Periodontal ligament & Zone of soft tissue balance................................................................... 17
Examples of when soft tissue integrity is lost:........................................................................... 18
AP position of the LLS is fixed within this narrow zone of balance .. Error! Bookmark not defined.
……………………………………….
3. Mohammed Almuzian, University of Glasgow, 2013 Page 3
To sum up the roles of soft tissue on orthodontics treatment , please remember these: ................. 19
1. The effect of ST on the treatment plan Ackerman & Proffit, 1997....................................... 19
2. Role on the orthodontic mechanics ................................................................................... 21
3. Effect of soft tissue on age related changes in the occlusion................................................ 23
4. Effect of soft tissue on orthodontics stability ..................................................................... 22
5. Roles of Soft Tissues in the development of different types of malocclusion........................ 19
Local factors........................................................................................................................... 23
4. Mohammed Almuzian, University of Glasgow, 2013 Page 4
Aetiology of malocclusion
Definition
Malocclusion can be defined as an appreciable deviation from the ideal that
may be considered aesthetically or functionally unsatisfactory (Andrews 1973).
History
When we talk about the aetiology of malocclusion it is fair to say that the
pendulum has swung backwards and forwards over the last hundred years
between principally malocclusion being due to genetic factors or being due to
environmental factors.
If you go back to the days of Edward Angle, he would say that virtually all of
the malocclusion is due to environmental and if you change the environment
then you will correct the malocclusion.
Clearly this is far from the truth as we know all now and over the more recent
years most people would agree that its due to a combination of genetics and
environment
Prevalence
1. Within the UK, the last Child Dental Health Survey found around 35% of 12
year olds with a definite need for orthodontic treatment on dental health or
aesthetic grounds, which increased to 43% when those started their treatment
(Chestnutt et al, 2006).
2. Proffit (2002) notes that from the results obtained from U.S Public Health
Service Surveys (Kelly et al, 1973) & (Kelly and Harvey 1977) that the
incidence of malocclusion in US children between the ages of 6-17 years of age
was approximately 75% with around 35% requiring some kind of orthodontic
treatment. (Poffit 2000)
3. Ethnicity also has a significant bearing on malocclusion.
5. Mohammed Almuzian, University of Glasgow, 2013 Page 5
Class II problems are commoner in white populations of northern European
descent.
Class III malocclusion is a common trait amongst Chinese and Japanese
societies.
Amongst African-Caribbean populations, anterior open bite is more common
than in Caucasians who, in turn, have a greater proportion of deep bite.
The etiological factors can be classified into
A. Genetics
B. Environment
Or
A. Skeletal factors
B. Soft tissue factors
C. Dentoalveolar disproportions (local factors)
D. Habit
In details
A. Genetics
This theory says that from the moment of fertilisation, genes contain all the
necessary information to regulate cells and tissue. All the genetic information is
in the neural crest cells. In general there are two types of genes involved
1. Regulatory genes: Gene called “homeobox gene” and this is thought to be
responsible for the whole development of the craniofacial complex
6. Mohammed Almuzian, University of Glasgow, 2013 Page 6
2. Intercellular regulatory genes: These are molecules which are further divided into 2
groups:
I. Growth factors, TGFa TGFb, NGF, FGF & PDGF
II. Steroid-Thyroxine Retinoic Acid (STRA) “super family”, it is thought that a
variation in these contributes to craniofacial malformations.
Certain terms in genetics
Genotype is defined as the genetic constitution of an individual, and may refer
to specified gene loci or to all loci in general.
Phenotype is the final product of a combination of genetic and environmental
influences.
Polygenic means many genes.
Epigenetic transmission, when the interaction of genes with each other and the
environment during development determine the phenotypic variation of the trait.
Multifactorial inheritance, the trait is determined by the interaction of a
number of genes at different loci, each with a small, but additive effect, together
with environmental factors
Discontinuous multifactorial traits, is Multifactorial trait but it need to reach
specific level or threshold to express itself.
Dominant it is the mode of inheritance when one copy of the effective gene are
required for expression of the trait.
Recessive, it is the mode of inheritance when two copies of the effective gene
are required for expression of the trait.
Evidences of genetic roles in development of malocclusion:
1. Society studies: Genetically homogenous societies exhibit similar levels of
malocclusion. Begg, 1964
2. Twin studies: Monozygotic twins are genetically identical and share a similar
trait of malocclusion Lundstroem (1949-1983) Twin Studies.
7. Mohammed Almuzian, University of Glasgow, 2013 Page 7
3. Genetic roles in the development of specific occlusal trait
Many developmental dental anomalies have been shown to occur together and
have a strong familial trend.
Genetic influence in CLP,Between 2 -20 genes are thought to be
responsible for the development of CLAP eg. TGFa.
Genetic influence on tooth size, number, form, shape, position and
eruption:
i. Supernumerary teeth genetically related Brooke 1974
ii. Ectopic canine genetically related Peck and Peck 1994
iii. Submerged primary teeth genetically related Kurol 1981
Arch length, crowding, spacing, cross bite and OB: Lundstroem
(1949-1983) Twin Studies
Vertical problems: Hunter 1968, Vertical growth pattern more
genetically correlated than horizontal one, if you had the long face in one
generation then chances are that you would have a long face in the next.
Cl2 D1 problems Harris 1969 showed a higher correlation between the
patient and the immediate family.
Cl2 D2 problems Familial occurrence has been shown in twin studies.
(Peck et al, 1998).
Cl3 problems Twin studies have shown concordance of mandibular
prognathism to be six times higher in twins than siblings (Downs, 1928;
Litton et al 1970; Lundstroem (1949-1983) Twin Studies.
4. Genetic roles in the development of soft tissue matrix: Van der Linden 1969
concludes that heredity control the shape and behaviour of soft tissue matrix
which is important in the development of certain type of malocclusion like class
II D2.
8. Mohammed Almuzian, University of Glasgow, 2013 Page 8
Notes:
These studies have also shown that malocclusion does not follow simple
Mendelian inheritance, but rather polygenetic or epigenetic transmission
May be one will ask why the sibling have the same crowding trait to their
parents? The answer is that they have the same skeletal and facial pattern
which are genetically determined and might face the same environment.
So what is the importance of determine the aetiology of malocclusion? As
we know the malocclusion is multifactorial inheritance and if the genetic has
more influence than environmental, then treatment will be difficult, but if the
environment factors are more expressive then the orthodontic prognosis is
better. However this is not easy since the diagnostic tools available to
differentiate between genetic and environmental are suggestive, blunt and not
precise.
B. Environmental factors
Revolutionary theory
Comparison of large population studies with archaeological records confirms
that malocclusion has become more common over the past 1000 years. It has
been hypothesized that dietary changes in modern societies, with increased
consumption of soft, energy-rich food, has resulted in less interproximal wear
between the teeth. (Begg, 1954). Additionally, hard diet requires vigorous
mastication, stimulating the growth of facial bones, particularly in the transverse
dimension of the maxilla and mandible.
However, the tooth wear is merely a by-product, brought about by diet-related
attrition and high masticatory activity, and has only a minor effect on tooth
alignment (Varrela, 2006).
9. Mohammed Almuzian, University of Glasgow, 2013 Page 9
Modern theory
The environment exerts its influence mainly through change on the soft tissue
matrix which has an influence on the skeletal and dental development leading to
malocclusion.
1. Functional matrix effect (Epi-Genetic theory)
2. Soft tissues stretching theory
In details
1. Epi-Genetic Theory
This is basically the functional matrix theory revised by Moss in 1997, he
divided the original functional matrix theory into two groups:
1. Capsular matrix
It acts indirectly and alters volume of capsule; it is further subdivided into 2
components
Neurocranial capsule, Responsible for growth of cranium
Orofacial matrix, Responsible for growth of maxilla and mandible
2. Periosteal matrix
Moss noted that when CHICLID fish are fed a soft diet they respond by
forming conical, non-moliform teeth and when they are fed a hard diet they
respond by forming moliform teeth, and so he uses this analogy that growth is
in some way related to function.
The skeletal muscles regulate the active growth process eg coroniod process
does not develop in the absence of the temporalis muscle. It acts directly on the
skeletal unit. However, it is not just the muscles involved, but also nerves,
blood vessels, glands etc.
10. Mohammed Almuzian, University of Glasgow, 2013 Page 10
2. Soft tissues theory
It is a change in the skeletal relationship which has arisen because of the need to
change the functional requirements of the body.
Environmental factors could be classified into:
1. Intra-uterine developmental pathology influencing facial
development
Disturbances in utero due to:
Teratogen like asprin or smoking causing CLP,
Alcohol causing Foetal Alcohol Syndrome.
Foetal moulding conditions or amnioitic band syndrome caused by low
aminiotic fluid or positional abnormality of the foetus during
development (Pier Robin syndrome)
Hemifacial Microsomia: Abnormality of 1st
arch caused by the rupture
of stapedial artery during intauterine life at the stage when the branchial
arches are developing with gross cellular distruction. this is an example
of a developmental pathology which is not genetic but which is an
illustration of something which could be an environmental factor
influencing growth and development of the face and jaws. The structures
which could be damaged include:
1. External ear – underdevelopment / accessory ear tags
2. Middle ear – deafness
3. Ramus – lack of vertical dimension
4. Soft tissue – masticatory muscle, skin + fascia
5. Occlusal cant due to facial assymetry
11. Mohammed Almuzian, University of Glasgow, 2013 Page 11
2. Postnatal factors
Possible causes may be physiological, habitual or pathological soft tissue
factors.
a. Habitual (Sucking habits) factors (see soft tissue factors)
Thumb sucking
Thumb-sucking is a habit (local factor) sucking of the digits will
create an AOB.
Secondary to the habit will be a tongue thrust to create an anterior
oral seal; therefore the tongue thrust is associated with the habit.
If habit stops before 7-9yrs old there will be reduction of AOB &
adaptive change in tongue thrust (stops).
But if habit remains beyond 7-9yrs then tongue becomes in-bred
and even if stop sucking digits the tongue thrust will maintain the
AOB unless you orthodontically change the environment.
b. Pathology
I. Traumatic:
The condyle is the commonest site of fracture in the mandible during childhood
and many go undiagnosed. In severe cases with bilateral fracture and dislocation
from the glenoid fossa, an anterior open bite can be one of the presenting
features due to a loss in ramus height.
A long-term sequelae of early trauma to the mandibular condyle can be
asymmetry, with an ipsilateral decrease in ramus height and deviation of the
chin point to the affected side
The severity of outcome is in part related to the age at the time of injury.
However, a high percentage of children sustaining a condylar fracture have
normal mandibular growth due to the reparative capacity of the condyle, even
when displaced from the glenoid fossa.
12. Mohammed Almuzian, University of Glasgow, 2013 Page 12
II. Inflammatory: Juvenile rheumatoid arthritis is an inflammatory arthritis
occurring before the age of 16 years and involving the temporomandibular
joints can result in the development of a severe class II malocclusion due to
restricted growth of the mandible
III. Hormonal: Excessive growth hormone resulting in overproduction of growth
hormone from an anterior pituitary tumour causes gigantism in children and
acromegaly in adults. In both circumstances, the patient presents with a
worsening class III malocclusion characterized by mandibular excess
c. Physiological soft tissue factors (see soft tissue factors below)
Soft tissue factors
Introduction
In orthodontic terminology means all non-calcified structures which are
relevant to tooth position and orthodontic treatment.
Soft tissues exert a variety of forces in multiple directions
Final tooth position is a position of equilibrium
Moving teeth against un-favourable soft tissue will result in relapse or
instability
Soft tissue can be a 1o aetiological factor or they can be a 2o aetiological
factor, secondary to the underlying 1o skeletal discrepancy
Soft tissue factors
1. Muscles of Facial Expression
2. Muscles of Mastication
3. Adenoids (mentioned before)
4. Fraenum (local soft tissue factor in diastema)
5. PDL (for neutral zone balance)
13. Mohammed Almuzian, University of Glasgow, 2013 Page 13
Muscles of facial expression, Sandy 1997
1. LIPS
a. At rest
b. In function
2. TONGUE
a. At rest
b. In function
Lips at rest (Position, lip line & competence)
Skeletal AP & vertical relationship as determinant factors for lip position, line
and competency. Three examples of patients with different skeletal
discrepancies:
1. Class II discrepancy with the skeletal relationship as primary aetiology with
lip trap as secondary aetiology
2. Increased vertical dimension with the skeletal relationship as primary
aetiology with lip incompetence as secondary aetiology causing increasing in
the proclination of the upper incisors.
3. Class II discrepancy with reduced vertical dimension with skeletal
relationship as primary aetiology & the high lower lip line as secondary
aetiology will result in the chin being closer to nose than it should be so the
lower lip covers more of upper incisors with greater restraining effect on upper
incisors leading to that the upper incisors become retroclined. However, the
upper lateral incisors are at a higher level therefore sometimes they get less
restraining effect and they become trapped outside the lip & become proclined.
Lips at function
A. Anterior oral seal
The causes of incompetent lip are:
1. AP & vertical skeletal discrepancy
14. Mohammed Almuzian, University of Glasgow, 2013 Page 14
2. Short lips
3. VME
4. Increase VH
5. Posterior growth rotation
6. Functional problem of the lip like scra as a result of trauma or CLP
The method of achieving an AOS is based upon: “The principle of least
physiological effort” by Prof Ballard, i.e. if you have an overjet of 10mm on
severe skeletal Class II, then the lower lip will, in trying to achieve an AOS,
meet the palatal mucosa because it is easier.
The types of anterior oral seal is achieved depends upon AP & vertical skeletal
relationship and include:
1. Circum-oral contraction in mild class II and AOB
2. Mandibular posturing in mild class II
3. Lower lip to maxillary incisor cingulum in moderate class II (lower lip trap)
4. Lower lip to palatal mucosa in sever class II (lower lip trap)
5. Lower lip to tongue in very sever class II
6. Upper lip to tongue in sever class III
B. Hyperactive or “strap- like” lower lip
It mainly cause retroclination of the lower incisor with associated LLS
crowding
It might cause increase in the OJ and OB.
Hyperactive lip bashes the lower incisors and the giggling forces leads to bone
loss and periodontal breakdown with loss of attachment
Methods of treatment tried with hyperactive lip:
1. Mentalis myotomy
2. Lip bumpers to stretch muscle fibres
15. Mohammed Almuzian, University of Glasgow, 2013 Page 15
3. If the lower incisors moved forward the using a permanent rigid retainer is
mandatory
Tongue at rest
Size
Very difficult to quantify.
The relative size of tongue reduces with age & adapts to the lower position
within arch i.e. less tendency to “thrust” with aging.
It can result in loss of vitality of incisors due to giggling forces of the tongue
bashing against upper incisors
Position
Tongue may be normal in size but be anteriorly placed to produce spacing and
AOB.
Partial glossotomy can result in spontaneous space closure and reduction of
AOB
Tongue in function
Tongue thrust
1. Adaptive (secondary) thrust
Thrust occurs in an attempt to achieve an oral seal when the lips are
incompetent or an AOB is already present from a digit sucking habit
Thrust may maintain an AOB but adapts if the AOB is corrected
2. Endogenous (primary) thrust
Very rare & affects 1% of population
Usually associated with lack of neuromuscular control e.g. Downs syndrome or
cerebral palsy.
May cause AOB which is difficult to close
16. Mohammed Almuzian, University of Glasgow, 2013 Page 16
Usually associated with a lisp, bimaxillary proclination, reverse COS in the
lower and deep COS in the upper.
The diagnosis is therapeutic which means the high tendency to relapse after
treatment.
Muscle of mastication
Hunt 1992 & 2006 found that long face syndrome has predominantly collage
fiber type 1 which is weak and long acting while short face syndrome has more
type 2 collagen fibres which is heavier and short acting.
Conditions associated with a loss of muscle tone, such as muscular dystrophy
and certain types of cerebral palsy, result in a downward and backward rotation
of the mandible, an increased lower face height and an anterior open bite
However (Proffit & Fields, 1983) believe that this muscle change is a result
from malocclusion.
Adenoid & Soft tissues stretching
It is a change in the skeletal relationship which has arisen because of the need to
change the functional requirements of the body.
Soft tissues stretching theory of Solow & Tallgren 1976, showed that:
airway obstruction lead to some sort of neuromuscular feedback mechanism
where the patient can't breathe through nose, so adopt a head up posture with
extension, In so doing, you now stretch the superhyoid muscles, skin + fascia.
This in turn imparts a force on the mandible and in turn means that the mandible
adopts a downward posture ( LAFH + MM angle) this will allow the tongue
to drop and imparts less force on maxillary arch in the lateral dimension which
with the unopposed action of the cheeks pushes the dentition into a narrower
arch which leads to cross bite situation
It was proposed that the “Adenoids” were the most important “soft tissue”
responsible for the difficulty in breathing through your nose then the adenoids
17. Mohammed Almuzian, University of Glasgow, 2013 Page 17
enlarged causing chronic constriction in the nasopharyx followed by the now
same pathway as “soft tissue stretch theory”. ARONSON (1979). The study
was:
1. looked at 81 pre-pubertal children who were obligate mouth breathers needing
adenoidectomy, 81% had features of adenoid face, 4% looked normal,
2. Features of the Adenoidal Face include
Flat middle 1/3rd
of face due to functional requirement of antrum which
are underdeveloped
Long Face due to neuromuscular feedback ie “head up + downward mandibular
posture”
Over eruption in mandibular arch over eruption due to lowered
mandibular posture
Narrow, High - arched Palate due to lowered tongue unopposed pressure
from cheeks
3. He measured the SN angle to the true vertical (angle “a”)
4. He looked at the size of this angle pre and 5yrs post adenoidectomy
5. He found that “normalisation” of this angle occurred ie it increased at the follow
up suggesting that head-up posture was not present
6. However, Vig (1985) that “ the magnitude of the morphological difference
attributed to adenoid removal was far too small to be of any clinical
significance”
Periodontal ligament & Zone of soft tissue balance
The equilibrium theory was described first by Weinstein in 1963 and hen
popularized by Proffit 1979, he divided the force of equilibrium into:
1. Primary factors are:
Intrinsic forces by tongue and lips
Forces from dental occlusion
18. Mohammed Almuzian, University of Glasgow, 2013 Page 18
Forces from the periodontal membrane.
Extrinsic forces: habits (thumb sucking, etc.), orthodontic appliances
2. Secondary factors in equilibrium
Postural relationships in the stomatognathic system
Secondary factors relating to eruption forces like failure of eruption
This chap also looked at the zone of balance by putting inducers on the labial &
lingual surfaces of the incisors and measuring the forces of soft tissues pushing
against the inducers over a 24hr period. He noted that the tongue forces always
exceeded that of the lips & cheeks both at rest and in function. So why aren’t
the teeth migrating and splaying out? The reasons:
A. AP forces
1. Size & duration of force, teeth won’t respond to short, sharp shock force.
2. Atmospheric pressure, every time you swallow you create negative pressure
inside the oral cavity
3. Contraction of periodontal transeptal ligament fibres.
4. Forces of occlusion
Examples of when soft tissue integrity is lost:
1. Afro-carribeans due to flaccid everted lip structures
2. Cancrum oris
3. Haemangiomas swelling of the lips/tongue/cheeks produces a “new” zone of
balance.
4. Bilateral cleft pre-maxilla swings forwards
5. Pd diseases
19. Mohammed Almuzian, University of Glasgow, 2013 Page 19
To sum up the roles of soft tissue on orthodontics treatment, please
remember these:
1. Roles ofSoft Tissues in the development of different types of malocclusion,
Mossey 1999, Turner & Sandy 1997
A. Class II division 1
Lip seal: lower lip to tongue seal can cause class II D 1 incisor relationship.
Lip trap and activity: lower lip trap may procline the upper incisors further.
Lip hyperactivity can retroclined teeth.
Habit: Digit habits can produce a Class II division 1 malocclusion even with
an underlying Class 1 skeletal pattern due to effects on the dentition.
B. Class II division 2
High lower lip line can retrocline the upper incisors with the development of a
Class II division 2 malocclusion.
Strap like lower lip cause retroclination of lower incisors
Hyperactivity of the massteric muscle can produce low facial height. Mills
(1982)
C. Class III
I. Soft tissues do not generally play a part; however, there is a tendency for the
lips and tongue to contribute towards dentoalveolar compensation.
II. Enlarged tonsils and mandibular forward posture due to nasal obstruction can
cause class III.
D. Bimaxillary proclination
Large tongue plays a significant part in the position of the incisors.
Flaccid and everted lips
Incompetent lips
E. Vertical anomalies
20. Mohammed Almuzian, University of Glasgow, 2013 Page 20
Habit: digit separates the jaws, the vertical equilibrium on the posterior teeth is
altered and a greater eruption of posterior teeth occurs, contributing to the
anterior open bite
Breathing: increased overjet and over-eruption of posterior teeth may occur also
as a result of altered head posture secondary to chronic nasal obstruction.
Tongue: A large tongue may encroach on the dental arch, impeding tooth
eruption anteriorly or laterally, depending on tongue position
Weak muscle of mastication
F. Transverse anomalies
Digit sucking can result in a transverse discrepancy between the jaws.
Chronic nasal obstruction can cause cross bite due to lower tongue position
Soft tissue lesions such as fibro-epithelial polyps and haemangiomas are
relatively uncommon causes of transverse anomalies but their effects can be
dramatic
G. Crowding
Changes in lip and tongue pressures may affect the development of the alveolus
and if the dental arch form is 'moulded' to a smaller arch size, then crowding
and malalignment may occur.
H. Spacing
Localized spacing may occur with a large 'fleshy' labial or lingual fraenum,
I. Tooth rotations and relapse
Contraction of these distorted supracrestal fibres may cause relapse of the
rotation if insufficient retention time is allowed for the reorganization of these
fibres
J. Soft tissue scarring in cleft lip and palate
21. Mohammed Almuzian, University of Glasgow, 2013 Page 21
Facial growth has been shown to be inhibited in patients with surgically
repaired cleft lip and palate anomalies compared with unrepaired clefts." This
effect is mediated by soft tissue scarring
2. The effect of ST on the treatment aims Ackerman & Proffit, 1997
This should be analysed according to aesthetic guidelines and the treatment
should be aimed to address the underlying malocclusion without compromising
the aesthetic zone or indeed, improving the aesthetic balance.
3. Role on the orthodontic biomechanics
A. Muscle of mastication
In treatment of class II malocclusion, "TB" appliances posture the mandible
forwards, stretching the elevator muscles of mastication and applying an
anteriorly directed force to the lower arch and a posteriorly directed force to the
upper arch.
The activator was designed to be a loose appliance, which dropped down in the
mouth, activating the tongue to cause the mandible to be brought forwards into
an improved occlusal position (Lee, 1984).
The Harvold appliance was intended to stretch the facial and the muscles of
mastication.
The Frankel functional impede activity of the lips, cheeks and tongue, thus
allowing normal facial growth (Lee, 1984).
Bite planes: They stretch the muscles of mastication vertically and allow any
teeth left unopposed to erupt.
B. The lips
Functional appliances posture the mandible forwards and bring the lower lip
forwards in relation to the upper incisors. An anterior oral seal should then be
possible which may assist retraction of the upper incisors in class II, div 1 cases
as well as improving lip tone where the lips are incompetent.
22. Mohammed Almuzian, University of Glasgow, 2013 Page 22
Lip bumpers utilise the musculature of the lips to apply a distal force to the
dental arch.
4. Effect of soft tissue on stability
1. Lips:
Lip incompetence reduces the of stability of OJ correction.
In cl2 d2, Successful treatment must therefore position the upper incisors
correctly in relation to lower lip.
Cases of corrected bimaxillary proclination tend to relapse due to the
weak tone of the lips.
2. Cheeks and tongue
Stability of arch dimensions: The equilibrium theory suggests that the opposing
forces of the tongue and lips and cheeks will render arch lengthening treatments
If the position of the tongue is low in the mouth, relapse may occur after
crossbite correction.
Tongue reduction has been mentioned previously in the stability of anterior
open bite.
3. Periodontal fiber; The supracrestal fibres of the PDL reorganise more slowly
than the rest of the ligament fibres and are stretched by rotational tooth
movements. A residual elastic rotational force is thus exerted on the tooth after
rotation. Edwards (1988) reported that circumferential fibrotomy (pericision)
reduced rotational relapse by 50%.
4. Stability of Corrective Jaw Surgery: Surgical correction of vertical dysplasias
are prone to relapse and Hunt (1992) has suggested that the proportion of
intermediate (IM) fibres in masseter and temporalis muscle may provide a
predictor of the likely degree of post-surgical stability. Intermediate fibres are
unique to masticatory muscles (Rinquist, 1973) and are thought to have the
ability to change into type I or type II fibres according to functional demands. A
23. Mohammed Almuzian, University of Glasgow, 2013 Page 23
corrected jaw relationship may induce these IM fibres to transform as required
and maintain the altered vertical dimension.
5. Effect of soft tissue on age related changes in the occlusion
1. Physiological mesial drift: the transeptal fibres that run between the teeth, as
shown by Moss and Picton (1974) has shown to be capable of causing tooth
movement. These fibres may play a role in late lower incisor crowding by
bunching the teeth progressively towards the front of the arch.
2. Migration: Migration is observed of anterior teeth whose periodontal support
has broken down. It has been suggested by Proffit(1979) that this-may be due to
the greater pressure of the tongue over the opposing force of the lips; the
stabilising role of the PDL having been lost.
Local factors
Local factors alone may cause a malocclusion or they may occur in any
combination of the factors listed above. Local factors include:
1. Abnormalities of tooth number
i) Anadontia
a) Rare condition
b) Total failure of development due to aplasia of dental lamina
c) Associated with ectodermal dysplasia (hereditary). This is characterized by:
Anadontia
Absence/reduced sweat glands leading to dry coarse skin
Sparse thin eye-brows
Defects of the nails
Skeletal deformities depressed bridge of nose/frontal bossing
24. Mohammed Almuzian, University of Glasgow, 2013 Page 24
Absence of alveolar processes of max.& mand.(since no teeth)
ii) Oligodontia
Severe hypodontia associated with systemic manifestations (ectodermal dysplasia)
iii) Hypodontia see hypodontia notes
iv) Supernumery teeth. The type are:
Conical supernumeries
Tuberculate supernumeries
Odontomes
Supplemental supernumeries
2. Early loss of primary teeth: the effects depend on:
Presence of crowding
Which Tooth lost
Timing / Age of loss
Which Arch
Eruption Sequence
3. Retained primary teeth
Retained incisors (A`s + B`s)
Retained molars
Ankylosed molars (submerged)
4. 5. Delayed eruption of permanent teeth
Impaction
Ectopic Crypt Position
Dilaceration
5. Loss of permanent teeth
Loss of 6`s (FPM)
Loss of 4s
Loss of 1s
25. Mohammed Almuzian, University of Glasgow, 2013 Page 25
6. Abnormalities of tooth form
Double tooth (Fusion / Gemination): Fusion between a lateral incisor and
a canine does not occur in the maxilla. The different nerve paths in the
maxillary and mandibular regions might explain this malformation
pattern
Macrodontia
Microdontia
Additional Cusps
Invaginated teeth
7. Habits
8. Abnormal Labial Freanum