Saliva in Dentistry PDF

Saliva (and saliva+on) [Oral and Dental Sciences] Miss H Rogers GDC ILOs  1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica>on to pa>ent management  1.1.6 Describe relevant and appropriate physiology and explain its...

Saliva (and saliva+on) [Oral and Dental Sciences] Miss H Rogers GDC ILOs  1.1.5 Describe relevant and appropriate dental, oral, craniofacial and general anatomy and explain their applica>on to pa>ent management  1.1.6 Describe relevant and appropriate physiology and explain its applica>on to pa>ent management Related topics:  Embryology  Salivary glands  Xerostomia  Skull  Regional anatomy Aim To gain an overview of saliva and its func>on, and the process of saliva>on Learning Outcomes By the end of this lecture you should be able to: 1.List both the organic and inorganic components of saliva, and describe their func>on 2.Describe the func>ons of saliva 3.Describe the mechanism of saliva>on 4.Outline the factors that can impact on salivary Low 3 What is saliva? How would you describe saliva? A colourless, slightly s>cky solu>on produced by the salivary glands. It is either serous or mucous in consistency- what do you understand by these terms? Qu: How much saliva do we produce in a day? Ans: Between 1-1.5 litres are produced every 24 hours 4 Sources of saliva by salivary gland Each of the major salivary glands (along with the minor) produce varying amounts of saliva: Salivary gland % of total volume Submandibular 60-65% Paro>d largest 25% Sublingual 5-10% Minor salivary glands on of saliva can be very di]cult to assess as the saliva produced by a food s>mulus may di^er from saliva produced by a wax s>mulus which is the method used to collect saliva for analysis Click on the link for more on tes>ng salivary Low 6 ‘Whole’ or ‘mixed’ saliva found in the mouth is- di^erent to ‘pure’ saliva produced in the glands. - Why do you think this may be? - What might be present in the saliva in the mouth that wouldn’t be found in the glands? Crevicular Luid, which is secreted from inLamed gingival pockets, is part of ‘whole’ saliva when periodontal disease exists. Food debris, epithelial cells and bacteria of the oral cavity are also present in saliva. 7 pH of saliva Res>ng pH can vary from person to person but the range is between 6.7-7.4 It can also vary depending on what has been eaten and the >me of day Those with a low pH tend to get more caries, whilst those with a higher pH produce more calculus - Why do you think this is? 8 Organic Components 9 Proteins There are several hundred di^erent proteins in saliva. Many possess an>bacterial proper>es. Mucin and enzymes are both proteins Immunoglobulins/Ig’s (An+-bodies) IgA, IgG and IgM These aid in the disposal of bacteria by clumping them together and rendering them unable to cling to the surfaces of the oral cavity. This process is termed agglu+na+on and works in conjunc>on with serous saliva (which washes it away). 10  Enzymes relaunaa Lysozyme – destroys harmful bacteria by lysis (destroying the cell wall) Lactoferrin – binds free iron therefore inhibi>ng bacterial metabolism Lactoperoxidase – also inhibits bacterial metabolism Amylase – begins the breakdown of cooked starches Ribonuclease – an enzyme catalyzing the endonucleoly>c cleavage of RNA Phosphatase – Involved in the process of calculus forma>on and remineralisa>on of caries 11 Mucin Proteins that give saliva its viscous/s>cky consistency. There are several di^erent mucin proteins. There are two types: Muco-proteins – contain more than 4% carbohydrate deriva>ves Glyco-proteins – contain less than 4% carbohydrate deriva>ves Waste Products Urea – can neutralise acids Uric acid Ammonia – formed from urea; raises pH All are by-products of cell metabolism 12 Cells Desquamated epithelial cells – constant turn over as worn/dead cells are replaced White blood cells – from the gingival crevice especially during inLamma>on. Bodies defence mechanism Commensal bacterial cells – exist in a symbio>c equilibrium with the host and prevent other more pathogenic bacteria from gaining a foot hold. Food Debris diceale. also impact periodontal Hormones Oestrogen and progesterone 13 Inorganic Components 14 The inorganic component consists mainly of mineral salts. When these are present in solu>on they are known as ions. Ions Their main func>on in saliva is their bu^ering e^ect thereby maintaining the pH levels -neutral Calcium phosphate ions play a major role regarding caries incidence and calculus forma>on 15  (inorganiz Other ions present: insaliva Sodium Potassium Magnesium Chloride Fluoride (remineralisa>on, an>-bacterial, topical e^ect resul>ng in teeth being more resistant to decay) Bicarbonate (bu^er) Sulphate Hydrogen 16 Gas Components Oxygen Nitrogen Carbon Dioxide – levels are higher in the salivary glands and its precipita>on (release) may be related to calculus forma>on 17 Func+ons of Saliva 18 Take a moment to list the possible func>ons of saliva. The components of saliva that have just been covered may help to give you some clues if you are struggling. 19 Protec+ve Glyco-proteins lubricate and waterproof the sok >ssues of the oral cavity. This help to: protect against abrasion aid speech maintain a healthy mucosa (stops it cracking and bacteria invading) They also form the salivary pellicle (it has been suggested that this helps to protect the enamel by forming a barrier to acid alacks). Serous saliva has a cleansing e^ect, removing food and bacterial debris. 20 BuSering Ions maintain the pH, making the environment unsuitable for bacterial colonisa>on and neutralising both acids and alkalis. There are higher numbers of bicarbonate ions during the higher salivary Low when ea>ng Diges+on food Salivary amylase begins the breakdown of cooked starches and helps form the bolus Taste Taste sensa>on can only be detected when substances are in solu>on- how may this impact someone with xerostomia? Impact diet reduced taste 21  Helps with immunoglobins ·. An+microbial speech Proteins and Ig’s help destroy or prevent colonisa>on by comfort. harmful bacteria reservoir Tooth Integrity ~ fluoride. Ions in saliva aid matura>on of the immature enamel of newly erupted teeth and aid repair from acid alacks In summary, saliva generally has a protec>ve func>on and pa>ents that have impaired saliva Low oken have rapid deposi>on of plaque with rampant caries and severe periodontal disease- how will this inLuence our management of these pa>ents? 22 Saliva and caries Hour does saliva protect oral cavity during carries formation ? 23  act as protection 1st layer Viscosity ↑ The salivary pellicle, formed by glyco-proteins, protects against acid but also encourages adherence 22nd layer can form plaquebirgiems by harmful plaque bacteria Supersatura+on of Inorganic Ions Help to maintain - - neutral PH. Act as a bu^er to control acid in solu>on and con>nuously aids control of the e^ects of demineralisa>on and remineralisa>on ↓ d fluoride is a key part 24  debris. away Serous Saliva -wash Its cleansing e^ect (minimal to moderate) may reduce the amount of fermentable carbohydrate available for conversion to acid Quan+ty This changes from: Day to night (1-1.5 litres during the day, 10ml at night) On s>mula>on eating or not. - A^ected by drugs, illness and radia>on Why do you think there is such a change between the day and night quan>>es? ~ no stimulus What is the e^ect on caries forma>on? What professions may this impact the most and why? Shift work (habits -. ↓ (sleep t eating) 25  inhibit demineralisation naturally contains calcium phosphate helps to mineralisation. promote can do this readily during short drops of pi/ acid attack minimal. can't keep up with prolonged periods of The Ionic See-Saw snacking While the saliva bu^ering system can reduce the extent of the fall in pHIwhen sugars enter the mouth, prolonged episodes can* exhaust the ability of the system to contain ion removal The immediate e^ect of a fall in pH is to increase: The free energy of the ions at the enamel/plaque interface The migra>on of ions from both enamel and plaque Saliva = acts as resovoir for calcium/phosphate. 26 How? As the pH falls below 6.0 the solubility limit of the plaque Luid increases thereby reducing the concentra>on of calcium and phosphate ions in the Luid When the solubility limit of the plaque Luid exceeds the calcium and phosphate ion products of plaque Luid these ions then begin to leave the enamel under a concentra>on gradient (higher concentra>on to lower concentra>on) - The pH level at which this occurs is around 5.5 Below this level and mineral ions (calcium and phosphate) leave enamel to enter plaque – enamel beings to demineralise 27 If the bu^ering ac>on is e^ec>ve and the pH rises, the addi>onal mineral ions in the plaque Luid will then exceed its capacity to hold them in solu>on because of satura>on This will cause the mineral ions to return to the enamel, again under a concentra>on gradient Therefore the enamel will remineralise The repeated Luctua>on in plaque pH produces a seesaw of ions across the interface between enamel and plaque Luid 28 Mechanism of Saliva+on Saliva>on is a reLex mechanism s>mulated by the sensory inputs: Sight Smell Taste It is also controlled by the sympathe>c and parasympathe>c nerve supply to the salivary glands The sympathe+c and parasympathe+c nerves have opposite e^ects which between them control the output from the salivary glands What do the highlighted terms above mean? What roles do you think the sympathe>c and parasympathe>c nerves have on the salivary glands? [Think about what happens when you are in a stressful situa>on or if you smell your favourite food…] Sympathe+c s+mula+on Reduces salivary Low (eg in stressful situa>ons your mouth goes dry). This is due to- vasoconstric>on. Parasympathe+c s+mula+on Increases salivary Low (eg when you are relaxed, your mouth waters at the sight/smell/taste of something appe>sing). This is due to - vasodila>on. Secretomotor supply to the salivary glands [resul+ng in saliva+on] 32 Glands in the hard & soX palate Sympathe+c Supply From the internal caro>d artery to the sphenopala>ne ganglion, then branches run with the greater pala+ne, lesser pala+ne and pharyngeal nerves of the trigeminal nerve (maxillary division). Parasympathe+c Supply From the superior salivary nucleus of the brain runs with the facial (7th) nerve, via the greater petrosal nerve, then the nerve of the pterygoid canal to the sphenopala>ne ganglion where there is a synapse. Post-synap>c pbres run from the ganglion along with branches of the maxillary division of the trigeminal nerve (greater pala+ne, lesser pala+ne and pharyngeal nerves) to the hard palate, sok palate and pharyngeal glands. See diagram on previous slide Submandibular and sublingual glands Sympathe+c Supply From the facial artery via the submandibular ganglion and the lingual nerve (branch on the mandibular division) to the submandibular and sublingual glands. Parasympathe+c Supply From the superior salivary nucleus of the brain via the facial (7th) nerve, via the chorda tympani branch to the submandibular ganglion where there is a is passed synapse. - Junction between 2 neurons where Signal J from. to the other Post ganglionic pbres run with the lingual nerve, a I branch of the mandibular division of the trigeminal nerve to the submandibular and sublingual glands See diagram on previous slide Paro+d glands Sympathe+c Supply From the middle meningeal artery via the o>c ganglion and the auriculotemporal nerve (a branch of the mandibular division) to the paro>d. Parasympathe+c Supply From the inferior salivary nucleus of the brain via the glossopharyngeal (9th) nerve, via the tympanic plexus of the middle ear and the lesser petrosal nerve to the o>c ganglion where there is a synapse. Post-ganglionic pbres run with the auriculotemporal branch of the mandibular division of the trigeminal (5th) nerve to the paro>d gland See diagram on previous slide Taste supply from the anterior two-thirds of the tongue  From the taste buds via the lingual nerve (mandibular division of the trigeminal nerve) to the submandibular ganglion then travel with the chorda tympani (a branch of the facial nerve) and the facial nerve to the nucleus solitarius in the brain Taste supply from the posterior third of the tongue  From the tongue via the glossopharyngeal (9th) nerve to the nucleus solitarius in the brain. Salivary Flow Factors 41 Take a few minutes to make a list of: food hunger Factors which might cause an increase in saliva Low  Factors which might cause a reduc+on in saliva Low  Radiotherapy Diabetes medication drugs smoking Why have you iden>ped these factors? 42 Increased Zow: Reduced Zow:  Mas>ca>on  Drugs  Irritants  Diabetes  Gingival condi>ons  Alcohol  Fear  Hunger  Radiotherapy  Smell/sight of food  Surgery  Teething in babies How many were on your list? Looking at the factors above, write your own brief notes on how they individually impact on salivary Low. 43 There are also a number of medical condi>ons that can have an impact on saliva produc>on. These can result in either: Parkinsons , motor neurone disease Neurological ~ : Hypersaliva+on- the excess produc>on of saliva cerebral palsy. or Xerostomia- dry mouth due to a reduc>on or Saliva gland disorders absence of saliva - Sjogrens syndrome , diabetes HIV/AIDS , radiation/chemotherapy Formulate your own list of condi>ons that may result in either hypersaliva>on or xerostomia. Why does it occur, and consider how it may impact on the delivery of dental care. 44 Saliva in den+stry 45 Cross-Infec+on Control + PPE Saliva can be a route of transmission for many viruses, one of many reasons why cross-infec>on control procedures must be followed. Which of the following can be transmiled in saliva? COVID-19 Hep B Hep C Herpes simplex (type 1) with active cold sores. - Epstein-Barr virus Tuberculosis Answer: ALL OF THEM! Can you iden>fy any others? 46 Addi+onal Resources Journal Ar+cles Tiwari M. Science behind human saliva. Journal of natural science, biology, and medicine, 2(1), 53–58 (2011). hlps://doi.org/10.4103/0976-9668.82322 Dodds, M., Roland, S., Edgar, M. et al. Saliva A review of its role in maintaining oral health and preven>ng dental disease. BDJ Team 2, 15123 (2015). hlps://doi.org/10.1038/bdjteam.2015.123 YouTube Kings College London- Spit! What your saliva says about you 47 References  Bath-Balogh, M., and Fehrenbach, M.J,. (2006) Dental embryology, histology, and anatomy. 2nd Ed. Elsevier.  Waugh, A., and Grant, A. (2006) Anatomy and physiology in health and illness. 10th Ed. Elsevier. 48