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Cover
Title Page
List of Contributors
About the Companion Website
1 Biomolecules
1. Introduction
2. Biological Bonding
3. Water, Water Everywhere
4. Amino Acids and Proteins
5. Enzymes
6. Nucleic Acids
7. Carbohydrates
8. Lipids
2 Cell Biology
1. Introduction
2. The Plasma Membrane
3. Membrane Proteins
4. Subcellular Organelles
5. Life and Death of a Cell
3 Tissues of the Body
1. Epithelia
2. Connective Tissues
3. Muscle
4 The Cardiovascular, Circulatory and Pulmonary Systems
1. Introduction
2. Cardiac System
3. Circulatory System
4. The Pulmonary System
5 The Nervous System
1. Introduction
2. Subdivisions of the Nervous System
3. Structural Components of the Nervous System
4. Anatomical Organization of Peripheral Somatic Nerves and Spinal Cord
5. The Autonomic Nervous System
6. Anatomy of the Brain
7. Summary of Brain Anatomy and Function
6 Introduction to Immunology
1. Introduction
2. Physical and Chemical Barriers to Infection
3. Microbiological Barriers to Infection
4. Molecular Elements of Innate Immunity: Antimicrobial Peptides and Complement
5. Cellular Elements of Innate Immunity
6. Innate Immune Signalling: Pattern Recognition, Chemotaxis and the Interferon Response
7. Adaptive Immunity I: B‐cells and Antibodies
8. Adaptive Immunity II: Antigen Presentation and T‐cell Activation
9. Inflammation
10. Immune Responses During Infection
11. Malfunctions of the Immune System
12. Vaccination
7 Oral Microbiology
1. Introduction
2. Oral Microbiota
3. Microbial Communities in the Mouth
4. Microbiology of Caries
5. Microbiology of Periodontal Diseases
6. Other Oral Infections
7. Summary
8 Introduction to Pathology
1. Introduction
2. Aetiology of Disease
3. Mechanisms of Disease
4. Inflammation
9 Head and Neck Anatomy
1. The Cranial Nerves
2. The Face and Neck
3. The Temporomandibular Joint
4. Muscles of Mastication
5. The Oral Cavity
6. The Pharynx and Larynx
7. The Orbit
8. The Paranasal Air Sinuses
10 Tooth Development, Tooth Morphology and Tooth‐Supporting Structures
1. Introduction
2. Early Tooth Development
3. Late Tooth Development
4. Dentinogenesis
5. Dentine Mineralization
6. Tooth Root Formation
7. Epithelial–Mesenchymal Interactions in Tooth Development
8. Amelogenesis
9. Enamel Mineralization
10. Tooth Morphology
11. Development of the Tooth‐Supporting Structures
11 Craniofacial Development
1. Introduction
2. Jaws and Support Skeleton
3. The Temporomandibular Joint
4. Cranial and Facial Sutures
5. The Tongue
6. The Palate
7. Craniofacial Syndromes
12 Saliva and Salivary Glands
1. Introduction
2. Salivary Gland Anatomy and Structure
3. How is Saliva Formed by Salivary Glands?
4. The Composition and Functions of Saliva
13 Introduction to Dental Materials
1. Introduction
2. The Structure of Matter
3. The Nature of Materials and Examples in Dentistry
4. Physical and Mechanical Properties
5. Safety, Biocompatibility and Adverse Reactions
6. Conclusions
Index
End User License Agreement

List of Tables

Chapter 06
1. Table 6.1 Physical barriers and chemical agents against infection and their properties.
2. Table 6.2 Host defences in the saliva.
3. Table 6.3 Phagocytic cells of the immune system and their function.
4. Table 6.4 Pattern‐recognition receptors and the ligands (and microorganisms) they recognize.
5. Table 6.5 The major families of cytokines and their functions.
6. Table 6.6 Function of immunoglobulin classes and subclasses.
7. Table 6.7 Processes which lead to self tolerance.
8. Table 6.8 CD4+ T‐cell subsets and their immunological function.
9. Table 6.9 Physical characteristics of acute inflammation.
10. Table 6.10 Conditions of immunodeficiency, their cause and symptoms.
11. Table 6.11 Some autoimmune diseases and their characteristics.
12. Table 6.12 Hypersensitivity reactions and their pathogenesis.
13. Table 6.13 UK vaccination programme for all.
14. Table 6.14 Vaccinations for special groups.
Chapter 07
1. Table 7.1 Predominant microbial genera found within the oral cavity.
2. Table 7.2 Oral streptococci.
3. Table 7.3 Types of dental caries.
4. Table 7.4 Classification of periodontal diseases.
5. Table 7.5 Types of oral candidosis.
Chapter 08
1. Table 8.1 Environmental causes of disease.
2. Table 8.2 Characteristics of different types of neoplasm.
Chapter 09
1. Table 9.1 Clinical tests for cranial nerve function.
Chapter 10
1. Table 10.1 Tooth morphology and anatomical features of the permanent dentition.
2. Table 10.2 Calcification and eruption dates for the deciduous dentition.
3. Table 10.3 Calcification and eruption dates for the permanent dentition.
Chapter 12
1. Table 12.1 Saliva composition and diagnostics.
2. Table 12.2 Rate of salivary flow from different glands.

List of Illustrations

Chapter 01
1. Figure 1.1 The chemical structure of water.
2. Figure 1.2 (a) Peptide bond and (b) amino acid ionization.
3. Figure 1.3 Classification of amino acids. Note that amino acids can be referred to using one‐ or three‐letter codes. This figure uses the former; so C represents cysteine, which in the three‐letter code would be Cys. SH is the thiol group of cysteine that can react to form a disulphide bridge (represented elsewhere by S–S) with another cysteine residue.
4. Figure 1.4 Three‐dimensional structure of salivary amylase.
5. Figure 1.5 Enzyme–substrate complexes and the transition state.
6. Figure 1.6 Mechanisms of enzyme inhibition. (a) Competitive inhibition. (b) Non‐competitive inhibition.
7. Figure 1.7 Allosteric regulation of protein kinase A.
8. Figure 1.8 The structure of the four nucleotides of DNA.
9. Figure 1.9 Nucleotides form antiparallel chains.
10. Figure 1.10 The structure of glucose.
11. Figure 1.11 Protein glycosylation.
12. Figure 1.12 Glycolysis.
13. Figure 1.13 The TCA cycle.
14. Figure 1.14 ATP structure and function.
15. Figure 1.15 Oxidative phosphorylation and ATP synthesis.
16. Figure 1.16 Regulation of phosphofructokinase.
17. Figure 1.17 Structure of fatty acids and triacylglycerols.
18. Figure 1.18 Absorption of lipids and packaging.
19. Figure 1.19 Production and fate of lipoproteins. For other definitions see text.
20. Figure 1.20 Fatty acid oxidation.
21. Figure 1.21 Gluconeogenesis.
Chapter 02
1. Figure 2.1 The basic structure of the plasma membrane.
2. Figure 2.2 The cell surface.
3. Figure 2.3 Types of membrane transport.
4. Figure 2.4 Membrane receptors. Diagram shows a kinase‐associated receptor. Phosphorylation (P) of the intracellular domain causes recruitment of STAT proteins which are then able to move to the nucleus to cause transcription of specific genes
5. Figure 2.5 The diagram shows a membrane‐bound enzyme (depicted as a Pacman shape) adjacent to its substrate, in this case also a membrane‐bound protein, which can be cut (‘cleaved’) by the enzyme.
6. Figure 2.6 The nucleus.
7. Figure 2.7 The structure of DNA.
8. Figure 2.8 DNA replication.
9. Figure 2.9 Transcription.
10. Figure 2.10 Protein translation.
11. Figure 2.11 The endoplasmic reticulum and Golgi complex.
12. Figure 2.12 Endocytosis.
13. Figure 2.13 The cell cycle.
14. Figure 2.14 Phases of the cell cycle.
15. Figure 2.15 Control of apoptosis.
Chapter 03
1. Figure 3.1 Classification of epithelial tissues.
2. Figure 3.2 Haematoxylin‐ and eosin‐stained section of oral epithelium.
3. Figure 3.3 Histological section showing adipocytes embedded in loose connective tissue.
4. Figure 3.4 Histological section through the periodontium showing the collagen fibres of the periodontal ligament.
5. Figure 3.5 Histological section taken from the trachea showing part of the C‐shaped hyaline cartilage ring.
6. Figure 3.6 Histological section showing the structure of fibrocartilage.
7. Figure 3.7 Histological section through the growth plate of a 5‐week‐old rat.
8. Figure 3.8 Longitudinal section through a femur to show the cortical and trabecular bone.
9. Figure 3.9 (a) Image of a ground section of mineralized cortical bone. The ‘tree‐ring’‐like structures that arise are called Haversian systems. (b) Ground section image of mineralized trabecular bone.
10. Figure 3.10 Histological section of demineralized woven bone formed by endochondral ossification. The blue‐coloured regions are remaining areas of hypertrophic cartilage which are being remodelled into woven bone.
11. Figure 3.11 Appearance and structure of skeletal muscle.
12. Figure 3.12 Structure of muscle and the sliding filament theory.
Chapter 04
1. Figure 4.1 The structure of the heart.
2. Figure 4.2 Blood flow and electrical conduction pathways in the heart.
3. Figure 4.3 A typical electrocardiogram (ECG).
4. Figure 4.4 Bowditch, Treppe or Staircase effect.
5. Figure 4.5 Frank–Starling response.
6. Figure 4.6 Basic anatomy of the circulatory system.
7. Figure 4.7 Structure and function of the different blood vessels.
8. Figure 4.8 Mechanisms to redistribute blood flow.
9. Figure 4.9 Maintenance of a stable blood pressure.
10. Figure 4.10 Effect of posture on blood distribution.
11. Figure 4.11 Basic anatomy of the lungs.
12. Figure 4.12 Mechanics of expiration and inspiration.
13. Figure 4.13 Diffusion and partial pressures of gases.
14. Figure 4.14 Control of breathing rate.
Chapter 05
1. Figure 5.1 Somatic and autonomic nervous systems.
2. Figure 5.2 Spinal and cranial nerves.
3. Figure 5.3 Neuronal morphology.
4. Figure 5.4 (a) Neuronal cell membranes. (b) Membrane and action potential.
5. Figure 5.5 Generation of an action potential.
6. Figure 5.6 The synapse.
7. Figure 5.7 Effects of neurotransmitter binding on postsynaptic membrane potential.
8. Figure 5.8 Myelination. (a) Schwann cell myelinating axon of peripheral neurone. (b) Oligodendrocytes myelinating axons of central neurones. (c) Action potential conduction in myelinated and unmyelinated axons.
9. Figure 5.9 Immunofluorescent detection of astrocytes (shown coloured red).
10. Figure 5.10 The structure of peripheral nerves.
11. Figure 5.11 Dorsal and ventral roots, dorsal root ganglion and the trigeminal ganglion.
12. Figure 5.12 The spinal cord.
13. Figure 5.13 Signal transmission from CNS to periphery.
14. Figure 5.14 The autonomic nervous system.
15. Figure 5.15 The sympathetic and parasympathetic nervous systems.
16. Figure 5.16 (a) Anatomy of the brain. (b) MRI normal T1 sagittal section scan of the human brain.
17. Figure 5.17 Anatomy of the hindbrain.
18. Figure 5.18 Anatomy of the midbrain.
19. Figure 5.19 The forebrain. (a) Brodmann’s areas. (b) Motor and sensory regions of the cerebral cortex. (c) Somatotopic map showing the areas of the body laid out on the sensory and motor cortices.
20. Figure 5.20 Sensory pathways.
21. Figure 5.21 Motor pathways.
Chapter 06
1. Figure 6.1 Activation and function of the human complement system. The complement system is activated by the recognition of protein and carbohydrate antigens on pathogen surfaces (often interacting with antibody molecules) and comprises a series of interacting pro‐enzymes (zymogens) that form a proteolytic cascade of activation leading to the localized production of a limited number of effector molecules which attempt to eliminate the pathogen. Cleavage of the complement component C3 by activation of the enzyme C3 convertase is the common endpoint for all three activation pathways. The products of this reaction (C3a and C3b) are key complement effector molecules. C3b also activates C5 convertase which cleaves C5, producing further effector molecules (C5a and C5b). Complement effector pathways comprise binding to antigen to enhance neutrophil phagocytosis (opsonization), stimulating movement (chemotaxis) of neutrophils into sites of tissue inflammation and formation of a membrane attack complex which punctures the bacterial cell membrane, causing lysis.
2. Figure 6.2 Structure of a typical antibody molecule. Antibodies are the soluble form of immunoglobulin (Ig) molecules and are large proteins with a complex 3D (globular) structure. The F_ab (antigen‐binding fragment) of different Ig molecules has a highly variable (clonal specific) amino acid sequence. The F_c (crystallizable fragment) has a limited variability and functions to bind to F_c receptors on phagocytes and NK cells. These fragments are joined by a flexible hinge region. The precise region of F_ab which binds antigen (A) is formed by the combination of variable region peptides on the heavy and light chains of the Ig molecule. The heavy and light chains have contiguous non‐variable regions (constant regions) which are joined together by disulphide bonds. The constant heavy chain peptide forms the F_c region of the Ig molecule and defines the antibody class (Table 6.6). T‐cell receptors (the antigen‐specific receptors on T‐cells; TCRs) have a similar globular structure and subunit composition (comprising TCRα and TCRβ chains or TCRγ or TCRδ chains).
3. Figure 6.3 Structure and recombination of Ig genes. The constant region of the Ig heavy chain is encoded by one of nine possible constant (C) genes in the genome depending on the class or subclass of antibody to be synthesizes. The variable region of the Ig heavy chain peptide (Figure 6.2) is encoded by a combination of three genes: one variable (V) gene, one diversity (D) gene and one joining (J) gene. The human genome has multiple variants of each of these genes, but only one of which contributes to Ig synthesis in each individual B‐cell clone; the possible combinatorial variations of Ig heavy chain variable region genes contribute to potential diversity of antigen‐binding sites on Ig molecules. DNA containing the specific combination of VDJC genes necessary for Ig synthesis is produced as the result of a somatic recombination process that takes place in maturing B‐cells. The Ig heavy chain peptide is combined with Ig light chain peptide (produced via a similar process) in immature B‐cells to produce the Ig molecule ready for export. T‐cell receptors are synthesized in developing T‐cells by analogous processes.
4. Figure 6.4 Activation of antigen‐specific T‐cells by antigen‐presenting cells. T‐cell receptors on naïve T‐cells recognize fragments of macromolecules produced as the result of ‘processing’ and ‘presentation’ in the context of MHC molecules in APCs such as dendritic cells. Other important connections take place at the surface of T‐cells and APCs. Thus, the CD4 molecule on one T‐cell subset (CD4+ T‐cells) serves to cooperate with TCRs in their interaction with MHC class II molecules on APCs (signal 1). Conversely, CD8+ T‐cells (which do not express CD4) interact exclusively with MHC class I molecules (not shown). The intercellular binding of so‐called co‐receptors such as B7.1 or B7.2 on APCs with CD28 on T‐cells (signal 2) is required in the initial stages of infection where naïve T‐cells, which have never encountered their cognate antigen before, are activated (for example, in a lymph node). Subsequent encounter with antigen/MHC molecules on target cells at the site of infection does not require this secondary signal. Activation of T‐cells also requires cytokines such as IL‐6, IL‐12 and TGF‐β derived from the APC (signal 3); the precise combination of cytokines influences T‐cell differentiation and therefore the effector phenotype of the T‐cell (see Table 6.8).
5. Figure 6.5 Holistic scheme illustrating the immune response to infection. Illustration of the dynamic of the host response to infection with a microbial pathogen. The immune system has several layers of effector mechanism which integrate to achieve destruction and/or elimination of pathogenic microorganisms. These are often categorized into innate and adaptive immunity although this is not always useful as these elements are highly integrated and mutually dependent. The exact nature of the host response and the stage at which the infection is halted is dependent on the site of infection, the exposure and the nature of the pathogen itself. Understanding the diverse elements of the immune response and their interaction is critical to the development of prophylactic measures (e.g. vaccines, allergen avoidance), therapies (anti‐inflammatory and immunosuppressive drugs) and novel approaches to clinical management (biomarkers).
Chapter 07
1. Figure 7.1 Micrographs of important oral bacteria. (a) Streptococcus gordonii, (b) Actinomyces naeslundii, (c) Fusobacterium nucleatum, (d) Treponema denticola.
2. Figure 7.2 Cervicofacial actinomycosis.
3. Figure 7.3 Gram stain of Candida albicans showing filamentous growth (true hyphae and pseudohyphae) arising from mother cells (blastospores).
4. Figure 7.4 Spatiotemporal model of plaque accretion. Primary colonizers associate with components of the acquired pellicle on the tooth surface and with each other via coadhesion/coaggregation. This generates a substratum with which incoming secondary colonizers can then associate. As the plaque matures, production of extracellular polymeric substance provides structural integrity and a conduit for the exchange of molecules. Nutritional adaptation, intermicrobial signalling (yellow stars) and beneficial/antagonistic interactions lead to the formation of distinct microbial societies within the plaque community that provide optimal metabolic networks and protection. Ultimately a climax community is formed that, in times of health, exists in equilibrium with its host.
5. Figure 7.5 Cariogenic attributes of S. mutans. Antigen I/II polypeptides promote attachment to gp340 within the acquired pellicle on the tooth surface, while glucosyltransferases (GTFs) synthesize glucans from fermentable carbohydrate. Glucans in turn are bound by glucan‐binding proteins (GBPs), providing additional structural stability to the plaque biofilm. Glucans, together with intracellular polysaccharide stores, can be broken down via glycolysis to yield energy, with lactic acid released as a waste product. This causes a drop in pH in the local environment. If this reaches pH 5.5 or lower, demineralization of the tooth surface occurs, leading to formation of a carious lesion.
6. Figure 7.6 Effects of periodontitis. Healthy periodontal tissue (left) contains connective tissue and alveolar bone, which support the tooth root. In addition, the oral epithelium covers this supporting tissue, and a specialized junctional epithelium connects it to the tooth surface. The space between the epithelial surface and the tooth is named the sulcus and is filled with gingival crevicular fluid. In cases of periodontitis (right), a dental plaque biofilm accumulates on the surface of the tooth and tooth root and causes the destruction of periodontal connective tissue and alveolar bone.
7. Figure 7.7 Radiograph showing dry socket (arrow), 3 months post‐extraction.
8. Figure 7.8 Candida‐associated denture stomatitis.
9. Figure 7.9 Angular cheilitis.
10. Figure 7.10 Herpes labialis (cold sore) caused by reactivation of HSV‐1.
11. Figure 7.11 Burkitt’s lymphoma caused by EBV.
12. Figure 7.12 Hand, foot and mouth disease. Arrow indicates tongue lesion.
13. Figure 7.13 Verruca vulgaris (wart) caused by human papillomavirus.
Chapter 08
1. Figure 8.1 Cell responses to injury.
2. Figure 8.2 Nuclear changes in cellular necrosis.
3. Figure 8.3 Types of necrosis.
4. Figure 8.4 Mechanism of neoplastic transformation.
5. Figure 8.5 Vascular events.
6. Figure 8.6 Explanation of vascular events: vasodilation.
7. Figure 8.7 Formation of oedema.
8. Figure 8.8 White cell distribution in the vessels of normal tissue. In normal blood flow, white and red blood cells are present in the centre of the vessel surrounded by the liquid part of the blood.
9. Figure 8.9 White cell distribution in inflammation. (1) In inflammation the white blood cells move to the edges of the vessel. This is called margination and is due to vascular stasis. (2) They then adhere to the endothelial cells. This is known as pavementation. (3) White blood cells emigrate between endothelial cells and into the tissues, attracted by chemokines.
10. Figure 8.10 Histological appearance of pus: dense accumulations of neutrophils which have multilobed nuclei (arrows). Macrophages are larger and engulf necrotic tissue and dead neutrophils (*).
11. Figure 8.11 Histological section of granulation tissue from a healing wound. Fibroblasts are indicated by arrows and endothelial cells lining the blood vessels by arrowheads. The large round cells containing brown pigment are macrophages which have engulfed red blood cells.
12. Figure 8.12 Maturation of granulation tissue. (a) Fibroblasts lay down collagen (arrow) and the tissue becomes less cellular and vascular. (b) Scar tissue composed of dense collagen may form.
13. Figure 8.13 Activation of macrophages.
14. Figure 8.14 Activation of lymphocytes.
15. Figure 8.15 Granulomatous inflammation.
16. Figure 8.16 Tuberculosis.
Chapter 09
1. Figure 9.1 The foremen of the skull.
2. Figure 9.2 The face.
3. Figure 9.3 (a) The TMJ and (b) muscles of mastication.
4. Figure 9.4 Sensory innervation of the oral cavity.
5. Figure 9.5 The orbit.
6. Figure 9.6 Schematic of eye with muscles.
Chapter 10
1. Figure 10.1 (a) The primitive oral cavity, the stomatodeum, with the ectomesenchyme (EM) lying beneath a lining of epithelium (arrows) and (b) the primary epithelial band (arrow).
2. Figure 10.2 The bud stage of tooth development. The bud is formed from the invading epithelium and concurrent condensation of surrounding ectomesenchymal cells.
3. Figure 10.3 The dental follicle (DF) surrounds the enamel organ and limits the dental papilla. It is this structure that is responsible for formation of the supporting structures of the tooth.
4. Figure 10.4 The enamel undergoes specific cellular changes in preparation for secretory function and four distinct cell layers are formed in this part of the tooth germ due to cellular proliferation and histo‐differentiation. These four cell layers are the inner enamel epithelium (IEE), outer enamel epithelium (OEE), the stellate reticulum (SR) and the stratum intermedium (SI), which is a two‐ to three‐cell‐layer‐thick area lying next to the inner enamel epithelium.
Chapter 11
1. Figure 11.1 Fates of Meckel’s cartilage. Meckel’s cartilage at the symphysis remains as persistent cartilage (blue). The main body of Meckel’s disappears during embryonic development (yellow). The most proximal part undergoes ossification and forms two of the three middle ear bones (red). The part between the lower jaw and middle ear transforms into the sphenomandibular ligament (green). Forming dentary bone in orange.
2. Figure 11.2 Jaw articulation in mammals and non‐mammals. A comparison of the jaw articulation. Mammal on left, bird on right. The homologous skeletal elements are shown in the same colour to illustrate the shift in function, position and size of these elements during evolution.
3. Figure 11.3 Schematic of the human skull showing the processes of the mandible (dentary bone) and its connection to the rest of the skull.
4. Figure 11.4 Schematic of the TMJ showing the position of the disc at the junction of the upper and lower jaw.
5. Figure 11.5 Skull vault: sutures. Sagittal (left) and anterior (right) views of the skull of a newborn outlining the sutures and fontanelles that separate the skull bones.
6. Figure 11.6 Tongue structure. Schematic showing the layout of taste buds, their embryonic origin and their innervation across the tongue.
7. Figure 11.7 Diagram of a taste bud showing the contribution of different receptor cells, basal and support cells to the bud.
8. Figure 11.8 Palate development and clefts. Virtual frontal sections through a human embryonic head. Left‐hand side: normal palate development. The shelves on either side of the tongue rise up, grow together and then meet in the midline. Once they have met in the midline the epithelial seam is lost to form a continuous palate separating the oral and nasal cavities. Right‐hand side: defects associated with palate development. Either one or both of the shelves can fail to rise. The shelves can rise but not grow together or the shelves can meet but the midline epithelial seam remains, leading to a submucosal cleft.
9. Figure 11.9 Primary tooth formation in cleft lip patients. Schematic showing the layout of developing tooth germs across the upper jaw with the placode (a thickening of the epithelium) for the lateral incisor forming at the fusion point between the maxillary and medial nasal processes. A cleft in this region splits the tooth placode leading to either loss of the tooth or the formation of supernumerary lateral incisors.
Chapter 12
1. Figure 12.1 Sources of salivary biomarkers. Salivary fluid is primarily derived from salivary gland secretion. Most of the protein content of saliva is due to salivary proteins synthesized and secreted by salivary acinar cells. However, saliva in the mouth also contains epithelial cells shed from the mucosal surfaces, blood cells (neutrophils) from gingivae and oral microorganisms, mainly species of bacteria. Small amounts of blood and tissue fluid proteins enter saliva mainly from the gingivae. GCF, gingival crevicular fluid.
2. Figure 12.2 Ductal systems and positions of major salivary glands. Injection of radio‐opaque contrast medium into the main ducts of salivary glands enables imaging of the ductal systems. (a) Positive image of the contrast medium in the parotid gland. (b) Negative image of the contrast medium in the submandibular gland. The opening of the main parotid duct at the level of the upper molars is clearly seen (arrows).
3. Figure 12.3 Histological appearance of salivary gland cells revealed by microscopy. The acinar cells of salivary glands have an appearance that depends upon the proteins and glycoproteins stored in granules in the cytoplasm. (a) Acinar cells of parotid glands stain darkly with H&E. (b) Minor mucus gland acinar cells contain abundant mucin‐containing storage granules that do not stain with H&E. (c) When mucin‐containing cells are stained with periodic acid–Schiff (PAS) reagent and Alcian blue, mucins stain dark blue. In this panel the staining reveals that submandibular glands have some mucin‐containing and many non‐mucin‐containing acini. (d) Sublingual gland acinar cells, mostly mucin‐containing; all are stained dark blue with Alcian blue. (Note: the images in a–d are taken at different magnifications.) (e) Myoepithelial cells are supporting cells that ‘wrap around’ the outside of acini and small ducts as revealed by fluorescent staining in this three‐dimensional image. (f) The apical membrane of acinar cells is different from the basolateral membrane and contains the membrane‐bound water‐transporting protein aquaporin 5 as shown by the fluorescent staining in this three‐dimensional image.
4. Figure 12.4 Control of salivary secretion by nerves. The salivary reflex begins with the detection of food and tastants such as acid and salt by taste buds and mechanoreceptors on the tongue; in addition the chewing of food is detected by mechanoreceptors in the periodontal ligament around teeth. Signals in afferent sensory nerves (green) are relayed to the salivary centres from where efferent parasympathetic nerves conduct signals to the salivary glands (blue). Sympathetic efferent nerves (red) arise from the thoracic spinal cord. Nerves within the CNS (black) innervate the salivary centres and influence nerve‐mediated signals to the salivary glands.
5. Figure 12.5 Intracellular coupling of salivary secretion in acinar cells. Fluid secretion is dependent mainly upon activation of muscarinic M3 receptors by acetylcholine released from parasympathetic nerves. The intracellular coupling mechanism is characterized by an elevation of calcium released from the endoplasmic reticulum (ER) and activation of chloride release. Protein secretion is mainly activated by release of noradrenaline by sympathetic nerves and activation β₁‐adrenoceptors; vasointestinal peptide released from parasympathetic nerves binds to vasointestinal polypeptide (VIP) receptors. Intracellular signalling is characterized by an increase in cyclic AMP (cAMP), which activates protein kinase A leading to exocytosis of protein storage granules and release of protein into saliva. Gq and Gs, G proteins; PLC, phospholipase C; PIP₂, phosphatidylinositol biphosphate; IP₃ – inositol triphosphate; IP₃R, IP₃ receptor; AdC, adenylate cyclase; PKA, protein kinase A.
6. Figure 12.6 Secretion of components of saliva and modification of composition by ducts. Saliva secretion is dependent upon the low intracellular sodium concentration created by the active sodium pump (ATP). Saliva secretion begins with the movement of sodium and chloride into the acinar lumen; water follows due to the osmotic gradient of salt and enters the acinar lumen by moving between cells or through the water channel (W), aquaporin 5, present in the apical membrane. Different ion transport membranes in the acinar cell membranes allow the salt and water movement: a chloride channel in the apical membrane is opened on glandular stimulation; sodium follows, travelling between acinar cells through leaky tight junctions (TJL). Chloride enters acinar cells through a chloride co‐transporting protein in the basolateral membrane which utilizes the concentration gradient of low intracellular sodium to drive chloride into the cell. Saliva secreted by acinar cells is isotonic. Ductal cells remove sodium and chloride due to the presence of membrane transporter proteins and the low intracellular sodium concentration created by the sodium pump. The tight junctions (TJ) between ductal cells are not leaky and do not allow the movement of water; also there is no water channel in ductal cells. Ductal cells can secrete bicarbonate (HCO₃⁻). Following modification by ducts, saliva becomes hypotonic.
7. Figure 12.7 Saliva on surfaces of the mouth. Saliva forms a fluid layer or film over all of the surfaces of the mouth and the film thickness depends upon the surface. The enamel surfaces of teeth have a thin fluid film of less than 5 µm while the anterior tongue has a film thickness of approximately 70 µm. Underneath the fluid layer are protein pellicles, adsorbed (bound) layers of salivary proteins and mucin which have a thickness of approximately 50 nm. All of these layers are important in providing salivary function in the mouth. The adsorption of the lubricating/hydrating mucin layer is dependent upon adsorption of other salivary proteins to the surfaces of epithelial cells and teeth. The layer is protective and renewable.
Chapter 13
1. Figure 13.1 The volume/temperature diagram for a glass‐forming liquid. Letters are referred to in the text.
2. Figure 13.2 Schematic two‐dimensional representation of the structure of silica SiO₂ in its (a) crystalline and (b) vitreous forms.
3. Figure 13.3 Schematic two‐dimensional representation of the structure of mixed‐oxide glass.
4. Figure 13.4 Examples of different monomers that are used to create polymeric materials used in dentistry (a) glycerol methacrylate and (b) methyl methcrylate.
5. Figure 13.5 Stress/strain curve of a ductile material showing the elastic (Young’s) modulus (E) given by the gradient of the linear region. Also shown are yield stress (σ_y), ultimate strength (σ_u) and fracture stress (σ_f). The area under the curve in the linear, elastic region is the resilience and that under the whole curve is the material’s toughness.
6. Figure 13.6 Shade guide for assessment of tooth colour and selection of appropriate dental material.