ORAL-PHYSIOLOGY-AND-OCCLUSION-PRELIMS.docx

**ORAL PHYSIOLOGY AND OCCLUSION PRELIMS** **ORAL PHYSIOLOGY** - Function of the stomatognathic system. It is a dynamic organization of organs and structures that functions as one. - **Stomatognathic system** is a system made up of highly coordinated structures comprising the human mas...

**ORAL PHYSIOLOGY AND OCCLUSION PRELIMS** **ORAL PHYSIOLOGY** - Function of the stomatognathic system. It is a dynamic organization of organs and structures that functions as one. - **Stomatognathic system** is a system made up of highly coordinated structures comprising the human masticatory apparatus. These structures are capable of acting as a single unit in order to perform the processes of mastication, deglutition, phonation, respiration, and other behavioral characteristics and activities. **MAJOR FUNCTIONS OF THE ORAL CAVITY** - **[CHEWING/ MASTICATION]** - It involves the coordinated action of the tooth, jaw, and muscle. - The teeth break down food into smaller particles. - The anterior and pre-molars cut, shears, and grinds the tissue/food. - The molars are the major structure for grinding. It triturates the food to become "bolus of food". The bolus is the end point of the process. - If there are problems in the teeth, there would be complications in mastication. It can result to resorption of the alveolar process/bone. - Muscles are major structures for mastication. This includes: **masseter, lateral pterygoid, temporalis, and middle pterygoid.** - Some muscles pull the jaw, some retract, and some just physically hangs the jaw. - Saliva is essential in the process of mastication. It aids in saving the structures of the oral cavity such as the tooth. - If there is no saliva, the tooth will dry out that can result to cracks and breakage of teeth. - **Xerostomia** is the condition when the oral cavity does not produce saliva. - The process of mastication ends when the food reached at the end of the mouth. - **DEGLUTITION** - The process when the bolus moves to the esophageal area. - Phases of swallowing: - **Oral Phase** -- tongue pushes the bolus to the back of the mouth. - **Pharyngeal Phase** -- the bolus moves to the pharynx and the soft palate elevates to close off the nasal cavity. - **Esophageal Phase** -- the bolus is pushed towards the esophagus and moves to the stomach via *peristalsis*. - Deglutition is associated with far more important process in digestion and nutrition. It basically aids in digestion and nutrition. - **ARTICULATION AND SPEECH** - The role of tongue and lips are important because they shape sounds by altering the flow of air through the oral cavity, and it manipulates the position of the vocal cords. - Obturators used in treating cleft palate helps the growth of tissue throughout the cleft and eventually closing it. - Surgery is not an option for infants with cleft palate because growth can still occur. - **TASTE** - Dentures can sometimes alter the taste since some covers the taste buds. That's why modifications take place to "not" cover those areas. **OCCLUSION** - Main functional idea of teeth. - Refers to the way the upper and lower teeth comes together when the mouth is closed. - Proper occlusion is essential for chewing, effective speech, and overall health. **TYPES OF OCCLUSIONS** 1. [Normal Occlusion] 2. [Malocclusion] - **Overbite** -- upper teeth have an excessive horizontal relationship with the lower teeth. - **Underbite** -- lower teeth are positioned ahead of the upper teeth. - **Crossbite** -- sideway bite; frequently with children - **Open Bite** -- there is a space between upper and lower teeth, in which the anterior teeth do not occlude with one another. - **Centric Occlusion** refers to when the upper and lower jaw are in maximum intercuspation. The cusps of the teeth interdigitate fully. It is the ideal occlusal relationship for efficient chewing and stability. - **Centric Relation** refers to the bone-to-bone relationship between the maxilla and mandible. It a repeatable man-stray position where the condyles are in antero-superior position within the glenoid fossa. Best seen in radiograph. - It functions as a reference point in dental treatment of orthodontics. **FUNCTIONAL OCCLUSION VS STATIC OCCLUSION** - [Functional occlusion] refers to how the tooth comes together during normal function. - [Static occlusion] refers to how the teeth are aligned when the jaws are closed in a resting position. **INTERDENTAL SPACE** - It is the triangular space in between each tooth. - Provides enough gap/space for proper alignment. - Creates space for food, air, and saliva to flow through to perform the oral cavity preparation. **DENTAL ARCH RELATIONSHIP** - This creates relationship/classification which enables us to duplicate or alter it. **SALIVARY GLANDS AND SALIVA** **[Introduction]** - The salivary glands are essential organs in the oral cavity, responsible for the production and secretion of saliva. - Saliva plays a crucial role in oral health, digestion, and overall well-being. **[Anatomy of the Salivary Glands]** - **Major Salivary Glands** - **Parotid Glands:** - **Location**: Situated in front of and below the ear. - **Size**: Largest of the salivary glands. - **Duct**: Stenson's Duct, which opens near the upper second molar. - **Secretion Type**: Primarily serous (watery and enzyme-rich) secretion. - **Submandibular Glands**: - **Location**: Beneath the lower jaw. - **Duct**: Wharton\'s duct, which opens into the floor of the mouth at the sublingual caruncle. - **Secretion Type**: Mixed secretion (both serous and mucous), but predominantly serous. - **Sublingual Glands**: - **Location**: Beneath the tongue. - **Ducts**: Multiple small ducts, with the main one being Bartholin\'s duct. - **Secretion Type**: Primarily mucous, which provides lubrication. - **Minor Salivary Glands**: - **Location**: Scattered throughout the oral cavity, including the lips, cheeks, palate, and tongue. - **Secretion Type**: Primarily mucous, with the exception of some serous glands on the tongue (von Ebner\'s glands). **[Physiology of Saliva Production]** - **Composition of Saliva:** - **Water (99%):** Essential for dissolving food and facilitating taste perception. - **Electrolytes**: Including sodium, potassium, calcium, bicarbonate, and chloride. - **Enzymes**: - **Amylase**: Begins the digestion of starches in the mouth. - **Lipase**: Aids in the digestion of fats, though more active in infants. - **Mucins**: Glycoproteins that lubricate and protect the oral tissues. - **Antimicrobial Agents**: - **Lysozyme**: Breaks down bacterial cell walls. - **Lactoferrin**: Binds iron, inhibiting bacterial growth. - **Immunoglobulin A (IgA)**: Provides immune protection in the oral cavity. - **Buffers**: Bicarbonate and phosphate buffer systems that maintain pH balance. - **Growth Factors and Cytokines**: Involved in tissue repair and immune responses. - **Regulation of Saliva Secretion**: - **Autonomic Nervous System (ANS):** - **Parasympathetic Stimulation**: Promotes a copious, watery secretion, primarily serous. - **Sympathetic Stimulation**: Produces a more viscous secretion, primarily mucous. - **Stimuli for Salivation:** - **Mechanical**: Chewing and food presence in the mouth. - **Chemical**: Taste and smell of food. - **Psychological**: Sight or thought of food (Pavlovian response). - **Inhibitory Factors**: Dehydration, stress, and certain medications can reduce saliva production. **[Functions of Saliva]** - **Digestive Functions**: - **Lubrication**: Facilitates the formation of a food bolus, making it easier to swallow. - **Enzymatic Action**: Amylase begins the breakdown of starches, while lipase initiates fat digestion. - **Taste Facilitation**: Dissolves food particles, allowing taste receptors to detect flavors. - **Protective Functions:** - **Mechanical Cleansing**: Washes away food particles and debris. - **Buffering**: Neutralizes acids produced by bacterial metabolism, protecting against tooth decay. - **Antimicrobial Action**: Protects the oral cavity from pathogenic microorganisms. - **Tissue Repair**: Growth factors in saliva promote the healing of oral tissues. - **Other Functions**: - **Speech**: Moistens the oral tissues, enabling smooth movement of the tongue and lips for articulation. - **Oral Homeostasis**: Maintains moisture balance, protecting the oral mucosa from drying out. **[Clinical Implications]** - **Xerostomia (Dry Mouth):** - **Definition**: A condition characterized by reduced or absent saliva flow. - **Causes**: Medications (e.g., antihistamines, diuretics), systemic diseases (e.g. Sjögren\'s syndrome, diabetes), radiation therapy for head and neck cancers, dehydration, and nerve damage. - **Symptoms**: Dry mouth, difficulty swallowing, altered taste, burning sensation, increased risk of dental caries, oral infections, and halitosis (bad breath). - **Management**: - **Saliva Substitutes**: Use of artificial saliva products to provide moisture. - **Saliva Stimulants**: Chewing sugar-free gum or sucking on sugar-free lozenges to stimulate natural saliva production. - **Hydration**: Encouraging frequent sips of water throughout the day. - **Medications**: Pilocarpine or cevimeline to stimulate saliva production in certain cases. - **Salivary Gland Disorders**: - **Sialadenitis**: Inflammation of a salivary gland, often caused by infection or obstruction (e.g., salivary stones). - **Sialolithiasis**: Formation of stones within the salivary ducts, leading to pain and swelling, especially during meals. - **Mumps**: A viral infection affecting the parotid glands, leading to painful swelling. - **Tumors**: Benign or malignant growths in the salivary glands, requiring clinical evaluation and possible surgical intervention. - **Hypersalivation (Sialorrhea):** - **Causes**: Neurological disorders (e.g., Parkinson\'s disease, cerebral palsy), side effects of medications, or oral inflammation. - **Management**: Addressing underlying causes, use of anticholinergic medications, or botulinum toxin injections to reduce saliva production. **[Conclusion]** - **Summary**: - The salivary glands and saliva play vital roles in oral health, digestion, and overall homeostasis. - Understanding the anatomy, physiology, and clinical implications of saliva is essential for diagnosing and managing related conditions. - **Clinical Relevance**: - Proper management of salivary gland disorders can significantly improve patients\' oral health and quality of life. - **Future Directions**: - Research into saliva biomarkers and therapeutic interventions for salivary gland disorders continues to evolve, offering new avenues for diagnosis and treatment. **[Academic Reflective Questions]** - **Question 1:** How does the autonomic nervous system regulate the secretion of saliva, and what are the clinical implications of this regulation in conditions like xerostomia or sialorrhea? - **Question 2:** Discuss the role of saliva in maintaining oral and systemic health. How does impaired saliva production impact both? - **Question 3**: Explain the relationship between salivary gland function and the prevention of dental caries. How does saliva contribute to oral hygiene? - **Question 4:** Consider the psychological impact of chronic xerostomia on a patient\'s quality of life. What strategies can healthcare providers use to mitigate these effects? - **Question 5:** In what ways do the composition and flow rate of saliva change in response to different types of stimuli (e.g., taste, chewing, psychological factors)? How can this knowledge be applied in a clinical setting? **MASTICATION** **What is Mastication?** **Mastication** is the process of chewing food in the mouth, involving the mechanical breakdown of food particles by the teeth. This is the first step of the digestive process, where food is prepared for further digestion and nutrient absorption in the stomach and intestines. **The Process of Mastication** 1. **Teeth and Chewing:** The teeth play a crucial role in cutting, grinding, and crushing food into smaller pieces. Different types of teeth are specialized for different tasks: - **Incisors**: Sharp front teeth for cutting food. - **Canines**: Pointed teeth for tearing food. - **Molars and Premolars**: Flat-topped teeth for grinding and crushing food. 2. **Saliva Production:** As you chew, the salivary glands in your mouth produce saliva, which is mixed with the food. Saliva contains enzymes like amylase, which begin breaking down carbohydrates into simpler sugars. Saliva also moistens the food, making it easier to swallow. 3. **Tongue and Cheek Coordination:** The tongue and cheeks help position the food between the teeth and form a bolus (a soft, moist ball of chewed food) that is ready to be swallowed. The tongue also plays a role in sensing the taste and texture of food, which is an essential part of the eating experience. 4. **Swallowing:** Once the food is sufficiently chewed and mixed with saliva, the bolus is pushed to the back of the mouth by the tongue, triggering the swallowing reflex, and the bolus then travels down the esophagus into the stomach. **Importance of Mastication for Digestion** 1. **Efficient Digestion**: Mastication increases the surface area of food particles, making it easier for digestive enzymes in the stomach and intestines to break down food. Proper mastication ensures that food is adequately prepared for the chemical processes that occur later in the digestive system. 2. **Nutrient Absorption**: Properly chewed food is more easily digested and absorbed in the intestines. When food is not chewed well, larger particles pass through the digestive tract undigested, leading to poor nutrient absorption and potential gastrointestinal issues. 3. **Salivary Enzyme Activation**: The enzymes in saliva, especially amylase, begin the digestion of carbohydrates right in the mouth. If food is not properly chewed, this initial stage of carbohydrate digestion is incomplete, which can affect overall digestion. 4. **Prevention of Overeating**: Chewing food slowly and thoroughly gives the brain time to receive signals of satiety (fullness). This can prevent overeating and contribute to better weight management. 5. **Oral Health**: Mastication also plays a role in maintaining healthy teeth and gums. Chewing stimulates saliva production, which helps neutralize acids and wash away food particles, reducing the risk of tooth decay and gum disease. **Key Points to Remember** - **Mastication** is the mechanical breakdown of food in the mouth through chewing. - **Teeth** are specialized for cutting, tearing, and grinding food, each type playing a specific role in the process. - **Saliva** contains enzymes that initiate digestion and helps moisten food for easy swallowing. - **Proper mastication** ensures better digestion, nutrient absorption, and prevents digestive issues. - **Chewing slowly** aids in satiety, helping prevent overeating. - **Oral health** benefits from mastication through increased saliva production, which helps maintain healthy teeth and gums. Mastication is a critical part of the digestive process, setting the stage for the efficient breakdown and absorption of nutrients, and promoting overall health. **Types of Teeth Involved in Mastication** Mastication, or the process of chewing, involves different types of teeth, each specialized for a specific function. Here\'s how each type contributes to the cutting, tearing, and grinding of food during mastication: **1. Incisors (Cutting)** - **Location**: These are the eight teeth at the front of the mouth---four on the top and four on the bottom. - **Function**: Incisors are designed for **cutting** food. Their sharp, thin edges act like scissors, slicing through food with precision. This is the first step in breaking down larger pieces of food into manageable sizes. - **Key Feature**: The flat, sharp edge of incisors makes them ideal for biting into food, such as fruits and vegetables. **2. Canines (Tearing)** - **Location**: There are four canines in total---two on the top and two on the bottom, located next to the incisors. - **Function**: Canines are used for **tearing** food, especially meat. They have pointed, sharp edges that allow them to pierce and rip through tougher textures that require more force. - **Key Feature**: The pointed tip of the canine teeth is perfect for gripping and tearing, aiding in the consumption of foods like meat. **3. Premolars (Grinding)** - **Location**: There are eight premolars, located behind the canines---four on the top and four on the bottom. - **Function**: Premolars are responsible for **grinding** food. They have a flat surface with ridges (cusps) that make them ideal for crushing and grinding food into smaller pieces, making it easier to swallow and digest. - **Key Feature**: The ridged surfaces of premolars are effective at breaking down food, particularly starchy and fibrous foods like bread and vegetables. **4. Molars (Grinding and Crushing)** - **Location**: Molars are the largest teeth, found at the back of the mouth---six on the top and six on the bottom, including wisdom teeth. - **Function**: Molars are the primary teeth used for **grinding and crushing** food. Their broad, flat surfaces are designed to handle the heavy work of breaking down food into a soft, digestible form. - **Key Feature**: Molars have a large, flat surface with multiple cusps, making them highly effective at grinding down all types of food, particularly dense or hard items like nuts and seeds. **Summary of Teeth Functions in Mastication** - **Incisors**: Sharp and thin, used for cutting and slicing food. - **Canines**: Pointed and strong, ideal for tearing food, especially meat. - **Premolars**: Flat with ridges, used for grinding and crushing food into smaller particles. - **Molars**: Large and broad, specialized in grinding and crushing food thoroughly. **Importance of Each Type** - **Incisors** initiate the mastication process by cutting food into bite-sized pieces. - **Canines** handle tougher textures, tearing food for further breakdown. - **Premolars and Molars** work together to grind and crush food, ensuring it is well-prepared for digestion. Understanding the roles of these different types of teeth highlights the efficiency of the human mouth in processing a wide variety of foods, each tooth type contributing uniquely to the mastication process. **Primary Muscles Involved in Mastication** Mastication, or the process of chewing, involves several key muscles that work together to move the jaw and manipulate food in the mouth. Each muscle has a specific role in ensuring efficient chewing. Here\'s a detailed look at the primary muscles involved and their functions: **1. Masseter** - **Location**: The masseter is located at the side of the jaw, running from the cheekbone (zygomatic arch) to the lower jaw (mandible). - **Function**: The masseter is the **strongest muscle** involved in mastication and is primarily responsible for the **elevation of the jaw**, allowing the mouth to close forcefully. This muscle is crucial for crushing and grinding food between the molars. - **Key Feature**: Its powerful contractions provide the force needed to break down tougher foods, like meat and nuts, making it essential for effective chewing. **2. Temporalis** - **Location**: The temporalis is a broad, fan-shaped muscle located on the side of the head, above the ear, and extends down to the mandible. - **Function**: The temporalis muscle is also involved in the **elevation of the jaw**, but it plays an additional role in **retracting** the jaw (pulling the jaw backward). This muscle aids in closing the mouth and maintaining the position of the jaw during chewing. - **Key Feature**: The temporalis helps control the jaw\'s movement and keeps the teeth aligned while chewing, preventing excessive movement and ensuring smooth, coordinated mastication. **3. Medial Pterygoid** - **Location**: The medial pterygoid muscle is located on the inside of the lower jaw (mandible), running parallel to the masseter but on the inner side. - **Function**: This muscle works in tandem with the masseter to **elevate the jaw**. Additionally, it helps with the **side-to-side (lateral) movements** of the jaw, which are important for grinding food between the teeth. - **Key Feature**: The medial pterygoid\'s ability to move the jaw laterally is essential for the thorough grinding and mixing of food, particularly when working with the molars. **4. Lateral Pterygoid** - **Location**: The lateral pterygoid is located above the medial pterygoid, extending from the base of the skull to the mandible. - **Function**: Unlike the other muscles, the lateral pterygoid is primarily responsible for **protruding the jaw** (moving the jaw forward) and **opening the mouth** by lowering the mandible. It also assists in the side-to-side movement of the jaw during chewing. - **Key Feature**: The lateral pterygoid is crucial for the initial stages of mastication, allowing the jaw to move in a coordinated manner as it opens and shifts from side to side, aiding in the grinding process. **Summary of Muscle Functions in Mastication** - **Masseter**: The strongest muscle, responsible for elevating the jaw and providing the force needed for crushing and grinding food. - **Temporalis**: Elevates and retracts the jaw, controlling and stabilizing jaw movement during chewing. - **Medial Pterygoid**: Elevates the jaw and enables lateral (side-to-side) movements for grinding food. - **Lateral Pterygoid**: Protrudes the jaw, helps open the mouth, and assists in lateral movements during chewing. **Importance of Each Muscle** - **Masseter** provides the main force for chewing tough foods. - **Temporalis** ensures smooth, controlled jaw movements, preventing dislocation or excessive movement. - **Medial Pterygoid** aids in the grinding of food, working with the masseter to ensure thorough breakdown. - **Lateral Pterygoid** allows the jaw to open and move side to side, essential for the complete and effective mastication of food. These muscles work in a coordinated manner to facilitate the complex movements required for chewing, ensuring that food is properly processed before it moves on to the next stage of digestion.