DENTIN HYPERSENSITIVITY - ETIOLOGY, DIAGNOSIS AND TREATMENTDr.Shraddha Kode
Dentinal Hypersensitivity is a common clinical condition which is sharp in character and of short duration in response to stimuli. It is associated with exposed dentin surfaces. This presentation provides a brief overview - its etiology, diagnosis and treatment.
Dental Caries, its pathophysiology and progression in enamel, dentine and cementum. We will also look at different zones of caries existing within in enamel and dentine.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
DENTIN HYPERSENSITIVITY - ETIOLOGY, DIAGNOSIS AND TREATMENTDr.Shraddha Kode
Dentinal Hypersensitivity is a common clinical condition which is sharp in character and of short duration in response to stimuli. It is associated with exposed dentin surfaces. This presentation provides a brief overview - its etiology, diagnosis and treatment.
Dental Caries, its pathophysiology and progression in enamel, dentine and cementum. We will also look at different zones of caries existing within in enamel and dentine.
Indian Dental Academy: will be one of the most relevant and exciting training center with best faculty and flexible training programs for dental professionals who wish to advance in their dental practice,Offers certified courses in Dental implants,Orthodontics,Endodontics,Cosmetic Dentistry, Prosthetic Dentistry, Periodontics and General Dentistry.
Children are a very special risk group for caries initiation and progression because of continuously changing eruption periods and therefore they need professional care.
It is an obligation of dental professionals to find appropriate strategies with the ultimate objective of producing sound tooth without resorting to operative methods.
Dental caries / dental implant 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.for more details please visit
www.indiandentalacademy.com
OSTEOLYSIS AND LOOSENING OF total hip arthroplasty IMPLANTS.pptx by dr vasu ...Vasu Srivastava
Aseptic Loosening of implants is caused by osteolysis. It is most significant factor limiting longevity of THA. Revision for loosening is 4x higher than next leading cause (dislocation at 13.6%), and its particularly problematic in younger patients [2].
Osteolysis is bone resorption caused by the body’s response to particulate debris generated as the THA implant wears out. Motion between any two components of the prosthesis (ie the femoral head and the acetabuluar liner, the head-neck junction of the femoral stem, or the liner and shell of the acetabulum) generates debris that floats around the joint. This debris stimulates a host response. Particles of metal, poly, or cement can all cause osteolysis, albeit different types of reaction. Osteolysis is important because it leads to implant loosening and/or periprosthetic fractures.
While osteolysis is the primary cause of loosening, infection must be part of the differential diagnosis.
Historical Perspective: Osteolysis was first described by Harris in 1976 and it was attributed to “cement disease” [3], because it was observed around the femoral component, and this was what started the drive for cementless implants. Yet after significant R&D, and development of cementless implants, osteolysis was still seen around the implants [4], and the histology was similar between cemented [5] and cementless implants [6]. Surgeons then looked for another cause of osteolysis and recognized that it was produced by wear particles.
STAGES OF OSTEOLYSIS
1) Debris production (ie poly wear) is the initial stage (we talk about metal debris in a separate section because it behaves totally differently, see section). Particulate debris in THA is produced by Abrasive and Adhesive wear (whereas the TKA produces delaminating wear: small fissures form within the poly).
▪ Adhesive wear is two surfaces bonding together causing the softer material to “peel” off as a thin film onto the harder surface during motion.
Volumetric wear is a specific type of adhesive wear, and it occurs as the femoral head articulates with the cup liner, and the amount of wear is proportional to the femoral head radius squared (therefore larger femoral head = more wear..this is why the initial Charnley implants, which used conventional poly, used a size 22 femoral head). Linear wear is caused by focused stress on a isolated part of the poly due to abnormal loading.
▪ Abrasive wear occurs when a harder surface (which is never completely smooth) cuts or ploughs through a softer surface, like a cheese grater. Both cause particle formation. Most wear occurs superiorly in the cup (or at the rim in cases of impingement).
The conventional PE wear from articulating with a Cobalt-chrome head is 0.10 mm/year. The ultramolecular weight poly (UMWPE, also known as highly-crosslinked poly) wear is about 0.02 mm/year. What is the difference between conventional and UMWPE?
Calculus (Classification, composition, microbiology etc.pptxDr. Faheem Ahmed
Calculus is a hard deposit that is formed by mineralization of dental plaque on the surfaces of natural teeth and dental prosthesis, generally covered by a layer of unmineralized plaque.
The presentation discusses about tooth enamel in detail including its formation, characteristics, structure and histological features along with its clinical considerations. It is well supported with diagrams for better understanding of the text.
Suggestions and feedback will be well appreciated.
Dental attrition is a type of tooth wear caused by tooth-to-tooth contact, resulting in loss of tooth tissue, usually starting at the incisal or occlusal surfaces. Tooth wear is a physiological process and is commonly seen as a normal part of aging.
Tooth discoloration is abnormal tooth color, hue or translucency. External discoloration is accumulation of stains on the tooth surface. Internal discoloration is due to absorption of pigment particles into tooth structure.
Dentine, unlike enamel, has the ability to react to the progression of caries due to the presence of odontoblasts. Odontoblasts can respond to irritation by depositing minerals in the dentinal tubules
Minimal intervention dentistry vs g.v blackEdward Kaliisa
Minimal Intervention Dentistry (MID) is a response to the traditional, surgical manner of managing dental caries, that is based on the operative concepts of G.V. Black of more than a century ago. MID is a philosophy that attempts to ensure that teeth are kept functional for life
Tooth resorption is the progressive loss of dentine and cementum by the action of osteoclasts. This is a physiological process in the exfoliation of the primary dentition, caused by osteoclast differentiation due to pressure exerted by the erupting permanent tooth
Nutrition and dental caries. Promotion of sound dietary practices is an essential component of caries management, along with fluoride exposure and oral hygiene practices. ... Fermentable carbohydrates interact dynamically with oral bacteria and saliva, and these foods will continue to be a major part of a healthful diet.
Dentinogenesis imperfecta (DI) is a genetic disorder of tooth development. This condition is a type of dentin dysplasia that causes teeth to be discolored (most often a blue-gray or yellow-brown color) and translucent giving teeth an opalescent sheen.
SEQUELAE. Most dental pain occurs as a result of caries. Initially, caries presents as a painless white spot (decalcification of the enamel, which may be reversible), followed by cavitation and brownish discoloration. ... Untreated caries can progress through the dentine to the pulp, which becomes inflamed (pulpitis)
Tooth decay, also known as dental caries is an epidemic, microbiological contagious disease of the teeth that ends in localized dissolution and damage of the calcified structure of the teeth. ... The time factor is significant for the commencement and development of caries in teeth.
Dental radiographs are commonly called X-rays. Dentists use radiographs for many reasons: to .... Detect any presence or position of unerupted teeth.2-D Conventional radiographs provide excellent images for most dental radiographic needs. Their primary use is to supplement the clinical examination by providing insight into the internal structure of teeth and supporting bone to reveal caries, periodontal and periapical diseases, and other osseous conditions.
Amelogenesis imperfecta is a disorder of tooth development. This condition causes teeth to be unusually small, discolored, pitted or grooved, and prone to rapid wear and breakage
The traditional method of detecting dental caries in clinical practice is a visual‐tactile examination often with supporting radiographic investigations.
These lecture slides, by Dr Sidra Arshad, offer a quick overview of physiological basis of a normal electrocardiogram.
Learning objectives:
1. Define an electrocardiogram (ECG) and electrocardiography
2. Describe how dipoles generated by the heart produce the waveforms of the ECG
3. Describe the components of a normal electrocardiogram of a typical bipolar leads (limb II)
4. Differentiate between intervals and segments
5. Enlist some common indications for obtaining an ECG
Study Resources:
1. Chapter 11, Guyton and Hall Textbook of Medical Physiology, 14th edition
2. Chapter 9, Human Physiology - From Cells to Systems, Lauralee Sherwood, 9th edition
3. Chapter 29, Ganong’s Review of Medical Physiology, 26th edition
4. Electrocardiogram, StatPearls - https://www.ncbi.nlm.nih.gov/books/NBK549803/
5. ECG in Medical Practice by ABM Abdullah, 4th edition
6. ECG Basics, http://www.nataliescasebook.com/tag/e-c-g-basics
Prix Galien International 2024 Forum ProgramLevi Shapiro
June 20, 2024, Prix Galien International and Jerusalem Ethics Forum in ROME. Detailed agenda including panels:
- ADVANCES IN CARDIOLOGY: A NEW PARADIGM IS COMING
- WOMEN’S HEALTH: FERTILITY PRESERVATION
- WHAT’S NEW IN THE TREATMENT OF INFECTIOUS,
ONCOLOGICAL AND INFLAMMATORY SKIN DISEASES?
- ARTIFICIAL INTELLIGENCE AND ETHICS
- GENE THERAPY
- BEYOND BORDERS: GLOBAL INITIATIVES FOR DEMOCRATIZING LIFE SCIENCE TECHNOLOGIES AND PROMOTING ACCESS TO HEALTHCARE
- ETHICAL CHALLENGES IN LIFE SCIENCES
- Prix Galien International Awards Ceremony
Lung Cancer: Artificial Intelligence, Synergetics, Complex System Analysis, S...Oleg Kshivets
RESULTS: Overall life span (LS) was 2252.1±1742.5 days and cumulative 5-year survival (5YS) reached 73.2%, 10 years – 64.8%, 20 years – 42.5%. 513 LCP lived more than 5 years (LS=3124.6±1525.6 days), 148 LCP – more than 10 years (LS=5054.4±1504.1 days).199 LCP died because of LC (LS=562.7±374.5 days). 5YS of LCP after bi/lobectomies was significantly superior in comparison with LCP after pneumonectomies (78.1% vs.63.7%, P=0.00001 by log-rank test). AT significantly improved 5YS (66.3% vs. 34.8%) (P=0.00000 by log-rank test) only for LCP with N1-2. Cox modeling displayed that 5YS of LCP significantly depended on: phase transition (PT) early-invasive LC in terms of synergetics, PT N0—N12, cell ratio factors (ratio between cancer cells- CC and blood cells subpopulations), G1-3, histology, glucose, AT, blood cell circuit, prothrombin index, heparin tolerance, recalcification time (P=0.000-0.038). Neural networks, genetic algorithm selection and bootstrap simulation revealed relationships between 5YS and PT early-invasive LC (rank=1), PT N0—N12 (rank=2), thrombocytes/CC (3), erythrocytes/CC (4), eosinophils/CC (5), healthy cells/CC (6), lymphocytes/CC (7), segmented neutrophils/CC (8), stick neutrophils/CC (9), monocytes/CC (10); leucocytes/CC (11). Correct prediction of 5YS was 100% by neural networks computing (area under ROC curve=1.0; error=0.0).
CONCLUSIONS: 5YS of LCP after radical procedures significantly depended on: 1) PT early-invasive cancer; 2) PT N0--N12; 3) cell ratio factors; 4) blood cell circuit; 5) biochemical factors; 6) hemostasis system; 7) AT; 8) LC characteristics; 9) LC cell dynamics; 10) surgery type: lobectomy/pneumonectomy; 11) anthropometric data. Optimal diagnosis and treatment strategies for LC are: 1) screening and early detection of LC; 2) availability of experienced thoracic surgeons because of complexity of radical procedures; 3) aggressive en block surgery and adequate lymph node dissection for completeness; 4) precise prediction; 5) adjuvant chemoimmunoradiotherapy for LCP with unfavorable prognosis.
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.
263778731218 Abortion Clinic /Pills In Harare ,sisternakatoto
263778731218 Abortion Clinic /Pills In Harare ,ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group ABORTION WOMEN’S CLINIC +27730423979 IN women clinic we believe that every woman should be able to make choices in her pregnancy. Our job is to provide compassionate care, safety,affordable and confidential services. That’s why we have won the trust from all generations of women all over the world. we use non surgical method(Abortion pills) to terminate…Dr.LISA +27730423979women Clinic is committed to providing the highest quality of obstetrical and gynecological care to women of all ages. Our dedicated staff aim to treat each patient and her health concerns with compassion and respect.Our dedicated group of receptionists, nurses, and physicians have worked together as a teamof receptionists, nurses, and physicians have worked together as a team wwww.lisywomensclinic.co.za/
Pulmonary Thromboembolism - etilogy, types, medical- Surgical and nursing man...VarunMahajani
Disruption of blood supply to lung alveoli due to blockage of one or more pulmonary blood vessels is called as Pulmonary thromboembolism. In this presentation we will discuss its causes, types and its management in depth.
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
Acute scrotum is a general term referring to an emergency condition affecting the contents or the wall of the scrotum.
There are a number of conditions that present acutely, predominantly with pain and/or swelling
A careful and detailed history and examination, and in some cases, investigations allow differentiation between these diagnoses. A prompt diagnosis is essential as the patient may require urgent surgical intervention
Testicular torsion refers to twisting of the spermatic cord, causing ischaemia of the testicle.
Testicular torsion results from inadequate fixation of the testis to the tunica vaginalis producing ischemia from reduced arterial inflow and venous outflow obstruction.
The prevalence of testicular torsion in adult patients hospitalized with acute scrotal pain is approximately 25 to 50 percent
- 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 Drug Discovery and Development .....NEHA GUPTA
The "New Drug Discovery and Development" process involves the identification, design, testing, and manufacturing of novel pharmaceutical compounds with the aim of introducing new and improved treatments for various medical conditions. This comprehensive endeavor encompasses various stages, including target identification, preclinical studies, clinical trials, regulatory approval, and post-market surveillance. It involves multidisciplinary collaboration among scientists, researchers, clinicians, regulatory experts, and pharmaceutical companies to bring innovative therapies to market and address unmet medical needs.
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.
The prostate is an exocrine gland of the male mammalian reproductive system
It is a walnut-sized gland that forms part of the male reproductive system and is located in front of the rectum and just below the urinary bladder
Function is to store and secrete a clear, slightly alkaline fluid that constitutes 10-30% of the volume of the seminal fluid that along with the spermatozoa, constitutes semen
A healthy human prostate measures (4cm-vertical, by 3cm-horizontal, 2cm ant-post ).
It surrounds the urethra just below the urinary bladder. It has anterior, median, posterior and two lateral lobes
It’s work is regulated by androgens which are responsible for male sex characteristics
Generalised disease of the prostate due to hormonal derangement which leads to non malignant enlargement of the gland (increase in the number of epithelial cells and stromal tissue)to cause compression of the urethra leading to symptoms (LUTS
2. Properties of enamel
Physical properties
hardest substance of human body.
Very brittle and low tensile strength (like ceramics
Enamel is translucent and varies in color from light
yellow to whitish.
thicker over cusps (2.5 mm) to a feather edge at the
cervical line.
it is partially permeable to some fluids, bacteria and
other products of the oral
it is totally acellular .
Unsupported enamel is subject to easily fracture or
cleave along rod boundaries
Chemical and inorganic
composition.
Highly mineralized crystalline structure, 96%
inorganic materials by weight; hydroxyapatite
(HA), 4% by weight organic content and water.
The organic matrix ,non-collagenous proteins and
enzymes. Of the enamel proteins 90% are
amelogenins and 10% are non-amelogenins. The
different types of non amelogenins associated with
formation of enamel are ameloblastin, enamelin
and tuftelin. The primary function of the organic
material is to direct the growth of enamel crystals .
3. Structure
Structure and organization
3 structures
Rods or prisms( crystallites formed by
,tomes process of the ameloblasts)
Rod sheath
Cementing inter rod substance
Rods are perpendicular to DEJ,wavy course
towards the cusp tip(Gnareled enamel).
Histological features
Gnarled enamel(sstrenth and resistance to fracture.
hunter- Schreger bands
Perikymata
Enamel cuticle(nasmyth’s membrane
Enamel pellicle(hinder bacterial attachment)
Enamel lamellae(planes of tension)
Enamel spindles (odontoblastic origin)
Enamel tufts(protein enmelin,anchor dentine to enamel
Cross striations
Striae of Retzious
Neontal line
6. PROGRESSION OF ENAMEL CARIES
1. INITIAL (submicroscopic)LESION
2. NONBACTERIAL ENAMEL
CRYSTAL DESTRUCTION
3. CAVITY FORMATION
4. BACTERIAL INVASION
INITIAL STAGE;4 ZONES
Zone 1: Translucent Zone.
Zone 2: Dark Zone
Zone 3: Body of the Lesion.
Zone 4: Surface Zone.
HAS 4 STAGES
7. 1: THE INITIAL (Submicroscopic) LESION
Seen as a white opaque spot that forms just adjacent to a
contact point It is conical in shape with its apex towards the
dentine, and a series of four zones of differing translucency
can be discerned. From the deepest, is a translucent zone (1%
pores, only demineralization);
the second dark zone(2-4% pores, both mineralization and
demineralization);
the third consists of the body of the lesion (the pore volume
is 5% at the periphery but increases to at least 25% in the
Center) and the fourth consists of the surface zone (1% pore
volume mineralization, radiopaque
8. Conti….
Cross-section of small carious lesion in enamel examined in quinoline by transmitted light (x 100).
Surface (a) appears to be intact. Body of lesion (b)
shows enhancement of striae of Retzius. Dark zone (c)
surrounds body of lesion while translucent zone (d) is
evident over entire advancing front of lesion. (From
Silverstone LM. In Silverstone LM et al, editors:
Dental caries,London and Basingstoke, 1981,
Macmillan.)
9. Zone 1: Translucent Zone.
loss of 1% of minerals
demineralization
In this zone, the pores or voids form along the enamel
prism (rod) boundaries, presumably because of the ease of
hydrogen ion penetration during the carious process.
10. Zone 2: Dark Zone.
The total pore volume is 2% to 4%.
the dark zone may be formed by deposition of ions into an area
previously only containing large pores remineralization.
There is also a loss of crystalline structure in the dark zone,
suggestive of the process of demineralization and remineralization.
The size of the dark zone is probably an indication of the amount of
remineralization that has recently occurred.
11. Zone 3: Body of the Lesion.
It has the largest pore volume, varying from 5% at the periphery to 25% at the
center. The striae of Retzius are well marked in the body of the lesion,
indicating preferential mineral dissolution along these areas of relatively higher
porosity.
The first penetration of caries enters the enamel surface via the striae of Retzius.
Bacteria may be present in this zone if the pore size is large enough to permit
their entry.
SEM(scanning electron microscopy )demonstrate the presence of bacteria
invading between the enamel rods (prisms) in the body zone .
12. Zone 4: Surface Zone.
It has a lower pore volume than the body of the lesion (less than 5%) and a radiopacity
comparable to unaffected adjacent enamel
The surface of normal enamel is hypermineralized by contact with saliva and has a
greater concentration of fluoride ion than the immediately subjacent enamel.
it serves as a barrier to bacterial invasion. As the enamel lesion progresses, conical-
shaped defects in the surface zone can be seen by SEM. These are probably the first
sites where bacteria can gain entry into a carious lesion.
Arresting the caries process at this stage results in a hard surface that may at times be
rough, though cleanable.
13. Cross-section of small carious lesion in enamel examined in quinoline by transmitted light (x 100).
Surface (a) appears to be intact. Body of lesion (b) shows
enhancement of striae of Retzius. Dark zone (c)
surrounds body of lesion while translucent zone (d) is
evident over entire advancing front of lesion. (From
Silverstone LM. In Silverstone LM et al, editors: Dental
caries,London and Basingstoke, 1981, Macmillan.)
14. 2: STAGE OF Nonbacterial ENAMEL CRYSTAL
DESTRUCTION
Highly mobile hydrogen ions permeate the organic matrix enabling them to
attack the surface of the apatite crystals which become progressively smaller.
Microdissection of the translucent zone has shown that the apatite crystals
have declined in diameter from the normal of 35-40 nm to 25-30 nm and in
the body of the lesion to 10-30 nm. In the dark zone, by contrast, enamel
crystals appeared to have grown to 50-100 nm and in the surface zone to 35-
40 nm. These findings also suggest that demineralisation and remineralisation
are alternating processes.
15. 3: CAVITY FORMATION
demineralisation comes to dominate the process.
prisms disappear - formation of pathways large enough for
bacteria to enter, bacteria reach amelodentinal junction –
spread laterally - enamel undermining.
pinhole lesion in enamel - large underlying cavity
fragmentation of enamel on the surface – clinically obvious
cavity
bacterial attack of dentine enabled
16. 4: BACTERIAL INVASION
Bacteria do not physically penetrate enamel until acid destruction of the
tissue has provided pathways large enough for them to enter
Defects eventually become large enough to allow bacteria to enter.
In superficial lesions; streptococcus viridans are predominant.
In deep lesions; mixed bacterial effect with lactobacilli predominating.
17. Enamel caries
Macroscopically
In case of a superficial caries:
Reversible white spot lesion without macroscopic
destruction
Fissure caries:
Whitish-yellowish or brownish-blackish
discoloration
