DENTAL ANATOMY & PHYSIOLOGY Physiology, Etiology, Epidemiology, Diagnosis, and TreatmentReviewed by:

Dental Anatomy and PhysiologyAfter viewing this lecture, attendees should be able to: Identify the major structures of the dental anatomy Discuss the primary characteristics of enamel, dentin, cementum, and dental pulp Describe the biologic functions that take place within the oral cavity

Dental Anatomy and PhysiologyPrimary (deciduous)Secondary (permanent)Definition (teeth): There are two definitions

Dental Anatomy and PhysiologyA tooth is made up of three elements:

WaterOrganic materialsInorganic materialsElements

Primary (deciduous)Consist of 20 teethBegin to form during the first trimester of pregnancyTypically begin erupting around 6 monthsMost children have a complete primary dentition by 3 years of age

Dental Anatomy and PhysiologyDentition (teeth): There are two dentitions1. Oral Health for Children: Patient Education Insert. Compend Cont Educ Dent.

Dental Anatomy and PhysiologySecondary (permanent)Consist of 32 teeth in most casesBegin to erupt around 6 years of ageMost permanent teeth have erupted by age 12Third molars (wisdom teeth) are the exception; often do not appear until late teens or early 20sDentition (teeth): There are two dentitions

Classification of Teeth:Incisors (central and lateral)Canines (cuspids)Premolars (bicuspids)Molars

Dental Anatomy and PhysiologyIdentifying Teeth Incisor Canine Premolar Molar

Dental Anatomy and PhysiologyIdentifying Teeth2 Incisor Canine Premolar MolarIncisors function as cutting or shearing instruments for food. Canines possess the longest roots of all teeth and are located at the corners of the dental arch. Premolars act like the canines in the tearing of food and are similar to molars in the grinding of food.Molars are located nearest the temporomandibular joint (TMJ), which serves as the fulcrum during function.

Dental Anatomy and PhysiologyApicalLabialLingualDistalMesialIncisalTeeth: IdentificationTooth Surfaces IncisalIncisal

Dental Anatomy and PhysiologyApical: Pertaining to the apex or root of the toothLabial: Pertaining to the lip; describes the front surface of anterior teethLingual: Pertaining to the tongue; describes the back (interior) surface of all teethDistal: The surface of the tooth that is away from the median lineMesial: The surface of the tooth that is toward the median line

Dental Anatomy and PhysiologyEnamel (hard tissue)Dentin (hard tissue)Odontoblast LayerPulp Chamber (soft tissue)Gingiva (soft tissue)Periodontal Ligament (soft tissue)Cementum (hard tissue)Alveolar Bone (hard tissue)Pulp CanalsApical Foramen

The Dental Tissues:

Anatomic CrownAnatomic RootPulp ChamberThe 3 parts of a tooth:Dental Anatomy and Physiology

Dental Anatomy and PhysiologyThe anatomic crown is the portion of the tooth covered by enamel.The anatomic root is the lower two thirds of a tooth. The pulp chamber houses the dental pulp, an organ of myelinated and unmyelinated nerves, arteries, veins, lymph channels, connective tissue cells, and various other cells.

EnamelDentinCementumDental Pulp

The 4 main dental tissues:Dental Anatomy and Physiology

StructureHighly calcified and hardest tissue in the bodyCrystalline in natureEnamel rodsInsensitiveno nervesAcid-solublewill demineralize at a pH of 5.5 and lower Cannot be renewedDarkens with age as enamel is lostFluoride and saliva can help with remineralizationDental Anatomy and PhysiologyDental TissuesEnamel2

Dental TissuesEnamel2Dental Anatomy and Physiology Enamel can be lost by:3,4 Physical mechanism Abrasion (mechanical wear) Attrition (tooth-to-tooth contact) Abfraction (lesions) Chemical dissolution Erosion by extrinsic acids (from diet) Erosion by intrinsic acids (from the oral cavity/digestive tract) Multifactorial etiologyCombination of physical and chemical factors

Softer than enamelSusceptible to tooth wear (physical or chemical)Does not have a nerve supply but can be sensitiveIs produced throughout lifeThree classifications PrimarySecondaryTertiaryWill demineralize at a pH of 6.5 and lowerDental TissuesDentin2Dental Anatomy and Physiology

Three classifications:Primary dentin forms the initial shape of the tooth. Secondary dentin is deposited after the formation of the primary dentin on all internal aspects of the pulp cavity.Tertiary dentin, or reparative dentin is formed by replacement odontoblasts in response to moderate-level irritants such as attrition, abrasion, erosion, trauma, moderate-rate dental caries, and some operative procedures.

Dental TissuesDentin2Dental Anatomy and Physiology

Dental Anatomy and PhysiologyDental TissuesDentin (Tubules)2Dentinal tubules connect the dentin and the pulp (innermost part of the tooth, circumscribed by the dentin and lined with a layer of odontoblast cells)The tubules run parallel to each other in an S-shape courseTubules contain fluid and nerve fibersExternal stimuli cause movement of the dentinal fluid, a hydrodynamic movement, which can result in short, sharp pain episodes

Dental Anatomy and PhysiologyPresence of tubules renders dentin permeable to fluorideNumber of tubules per unit area varies depending on the location because of the decreasing area of the dentin surfaces in the pulpal directionDental TissuesDentin (Tubules)2

Association between erosion and dentin hypersensitivity3 Open/patent tubules Greater in number Larger in diameter Removal of smear layer Erosion/tooth wear

Dental Anatomy and PhysiologyDental TissuesDentin (Tubules)2

Dental Anatomy and PhysiologyThin layer of mineralized tissue covering the dentin Softer than enamel and dentinAnchors the tooth to the alveolar bone along with the periodontal ligament Not sensitive

Dental TissueCementum2

Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the coronal pulpPulp canals traverse the root of the toothTypically sensitive to extreme thermal stimulation (hot or cold)Dental TissueDental Pulp2Dental Anatomy and Physiology

Pulpitis is inflammation or infection of the dental pulp, causing extreme sensitivity and/or pain. Pain is derived as a result of the hydrodynamic stimuli activating mechanoreceptors in the nerve fibers of the superficial pulp (A-beta, A-delta, C-fibers). Hydrodynamic stimuli include: thermal (hot and cold); tactile; evaporative; and osmotic These stimuli generate inward or outward movement of the fluid in the tubules and activate the nerve fibers. A-beta and A-delta fibers are responsible for sharp pain of short duration C-fibers are responsible for dull, throbbing pain of long duration Pulpitis may be reversible (treated with restorative procedures) or irreversible (necessitating root canal). Untreated pulpitis can lead to pulpal necrosis necessitating root canal or extraction. Dental TissueDental Pulp2,5Dental Anatomy and Physiology

GingivaAlveolar BonePeriodontal LigamentCementumPeriodontal Tissues6Dental Anatomy and Physiology

Gingiva: The part of the oral mucosa overlying the crowns of unerupted teeth and encircling the necks of erupted teeth, serving as support structure for subadjacent tissues.

Dental TissueDental Tissue6Dental Anatomy and Physiology

Alveolar Bone: Also called the alveolar process; the thickened ridge of bone containing the tooth sockets in the mandible and maxilla.

Dental TissueDental Tissue6Dental Anatomy and Physiology

Periodontal Ligament: Connects the cementum of the tooth root to the alveolar bone of the socket.

Dental TissueDental Tissue6Dental Anatomy and Physiology

Cementum: Bonelike, rigid connective tissue covering the root of a tooth from the cementoenamel junction to the apex and lining the apex of the root canal. It also serves as an attachment structure for the periodontal ligament, thus assisting in tooth support.Dental TissueDental Tissue6Dental Anatomy and Physiology

PlaqueSaliva pH ValuesDemineralizationRemineralization

Oral Cavity/Environment7,8Dental Anatomy and Physiology

Dental Anatomy and PhysiologyPlaque:7,8is a biofilm contains more than 600 different identified species of bacteria there is harmless and harmful plaque salivary pellicle allows the bacteria to adhere to the tooth surface, which begins the formation of plaqueOral Cavity

Dental Anatomy and PhysiologySaliva:7,8complex mixture of fluidsperforms protective functions:lubricationaids swallowingmasticationkey role in remineralization of enamel and dentinbuffering Oral Cavity

Dental Anatomy and PhysiologypH values:7,8measure of acidity or alkalinity of a solution measured on a scale of 1-14 pH of 7 indicated that the solution is neutralpH of the mouth is close to neutral until other factors are introduced pH is a factor in demineralization and remineralizationOral Cavity3. Strassler HE, Drisko CL, Alexander DC.

Dental Anatomy and PhysiologyDemineralization:7,8mineral salts dissolve into the surrounding salivary fluid: enamel at approximate pH of 5.5 or lowerdentin at approximate pH of 6.5 or lower erosion or caries can occur Oral Cavity

Dental Anatomy and PhysiologyRemineralization:7,8pH comes back to neutral (7)saliva-rich calcium and phosphatesminerals penetrate the damaged enamel surface and repair it:enamel pH is above 5.5dentin pH is above 6.5Oral Cavity

Dental Anatomy & PhysiologyReferencesReferences1. Oral Health for Children: Patient Education Insert. Compend Contin Educ Dent. 2005;26(5 Suppl 1):Insert. 2. Sturdevant JR, Lundeen TF, Sluder TB Jr. Clinical significance of dental anatomy, histology, physiology, and occlusion. In: Robertson TM, Heymann HO, Swift EJ Jr, eds. Sturdevants Art and Science of Operative Dentistry. 4th ed. Mosby: St. Louis, MO; 2002:13-61. 3. Strassler HE, Drisko CL, Alexander DC. Dentin hypersensitivity: its inter-relationship to gingival recession and acid erosion. Inside Dentistry. 2008;29(5 Special Issue):3-4. 4. Imfeld T. Dental erosion. Definition, classification and links. Eur J Oral Sci. 1996;104(2 (Pt 2)):151-155.5. Dentin hypersensitivity: current state of the art and science. In: Pashley DH, Tay FR, Haywood VB, et al. Dentin Hypersensitivity: Consensus-Based Recommendations for the Diagnosis and Management of Dentin Hypersensitivity. Inside Dentistry. 2008;4(9 Special Issue):8-18.6. Dorlands Medical Dictionary. 29th Ed. Philadelphia, PA: W. B. Saunders Company; 2000.7. Robertson TM, Lundeen TF. Cariology: the lesion, etiology, prevention, and control. In: Robertson TM, Heymann HO, Swift EJ Jr, eds. Sturdevants Art and Science of Operative Dentistry. 4th ed. Mosby: St. Louis, MO; 2002:63-132.8. Tooth Erosion in ChildrenUS Perspective. Inside Dentistry. 2009;5(3 Suppl):8.

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Dental Anatomy & Physiology

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There are two general categorizations for teeth:Primary (deciduous) teethSecondary (permanent) teethThere are two general categorizations for teeth:Primary (deciduous) teethSecondary (permanent) teethPrimary (deciduous)Consist of 20 teethBegin to form during the first trimester of pregnancyTypically begin erupting around 6 monthsMost children have a complete primary dentition by 3 years of ageSecondary (permanent)Consist of 32 teeth in most casesBegin to erupt around 6 years of ageMost permanent teeth have erupted by age 12Third molars (wisdom teeth) are the exception; often do not appear until late teens or early 20sTeeth may be classified based on structure/function:Incisors (central and lateral)Canines (cuspids)Premolars (bicuspids)Molars Incisors (central and lateral)The incisors are located near the entrance of the oral cavity and function as cutting or shearing instruments for food. From a proximal view, the crowns of these teeth have a triangular shape with a narrow incisal surface, including the incisal edge, and a broad cervical base. The incisors contribute significantly in cutting actions and other functions; esthetics; and phonetics.CaninesThe canines possess the longest roots of all teeth and are located at the corners of the dental arch. They function in the seizing, piercing, and tearing of food, as well as in cutting. From a proximal view the crown also has a triangular shape with a thick incisal ridge. The stocky anatomic form of the crown and length of the root are reasons why these teeth are strong, stable abutment teeth for a fixed or removable prosthesis. The canines serve as imortant guides in occlusion because of their anchorage and position in the dental arches.PremolarsThe premolars serve a dual role in function: they act like the canines in the tearing of food and are similar to molars in the grinding of food.Whereas the first premolars are angular, with their facial cusps resembling the canines, the lingual cusps of the maxillary premolars and molars have a more rounded anatomic form. The occlusal surfaces present in a series of curves in the form of concavities and convexities that should be maintained throughout life for correct occlusal contacts and function.MolarsThe molars are large, multicusped, strongly anchored teeth located nearest the temporomandibular joint (TMJ), which serves as the fulcrum during function. These teeth have a major role in the crushing, grinding, and chewing of food to the smallest dimensions suitable for deglutition. The occlusal surfaces of both premolars and molars act as a myriad of shears that function in the final mastication of food. The premolars and molars are also important in maintaining the vertical dimension of the face.

All definitions from: Sturdevant JR, Lundeen TF, Sluder TB Jr. Clinical significance of dental anatomy, histology, physiology, and occlusion. In:Roberson TM, Heymann HO, Swift EJ Jr, eds. Sturdevant's Art and Science of Operative Dentistry. 4th ed. St. Louis, MO: Mosby; 2002:15-16. *Tooth surfaces include:Apical: Pertaining to the apex or root of the toothLabial: Pertaining to the lip; describes the front surface of anterior teethLingual: Pertaining to the tongue; describes the back (interior) surface of all teethDistal: The surface of the tooth that is away from the median lineMesial: The surface of the tooth that is towards the median line*Tooth surfaces include:Apical: Pertaining to the apex or root of the toothLabial: Pertaining to the lip; describes the front surface of anterior teethLingual: Pertaining to the tongue; describes the back (interior) surface of all teethDistal: The surface of the tooth that is away from the median lineMesial: The surface of the tooth that is towards the median line*The anatomic tooth crown is the portion of the tooth covered by enamel.The anatomic root is the lower two thirds of a tooth. The roots are normally subgingival, buried in bone, and serve to anchor the tooth in position.The pulp cavity houses the dental pulp, an organ of myelinated and unmyelinated nerves, arteries, veins, lymph channels, connective tissue cells, and various other cells involved in formative or developmental, nutritive, sensory, protective, and defensive or reparative processes.

*The anatomic tooth crown is the portion of the tooth covered by enamel.The anatomic root is the lower two thirds of a tooth. The roots are normally subgingival, buried in bone, and serve to anchor the tooth in position.The pulp cavity houses the dental pulp, an organ of myelinated and unmyelinated nerves, arteries, veins, lymph channels, connective tissue cells, and various other cells involved in formative or developmental, nutritive, sensory, protective, and defensive or reparative processes.

*The anatomic tooth crown is the portion of the tooth covered by enamel.The anatomic root is the lower two thirds of a tooth. The roots are normally subgingival, buried in bone, and serve to anchor the tooth in position.The pulp cavity houses the dental pulp, an organ of myelinated and unmyelinated nerves, arteries, veins, lymph channels, connective tissue cells, and various other cells involved in formative or developmental, nutritive, sensory, protective, and defensive or reparative processes.

*

The 4 main dental tissues are:EnamelDentinCementumDental pulp

StructureHighly calcified and hardest tissue in the bodyCrystalline in natureEnamel rodsInsensitiveno nervesAcid-solublewill demineralize at a pH of 5.5 and lower Cannot be renewedDarkens with age as enamel is lostFluoride and saliva can help with remineralizationSofter than enamelSusceptible to tooth wear (physical or chemical)Does not have a nerve supply but can be sensitiveIs produced throughout lifeThree classifications PrimarySecondaryTertiaryWill demineralize at a pH of 6.5 and lower

Primary dentin forms the initial shape of the tooth. It is usually completed 3 years after tooth eruption (for permanent teeth). Secondary dentin is deposited after the formation of the primary dentin. Secondary dentin forms on all internal aspects of the pulp cavity, but in the pulp chamber of multirooted teeth it tends to be thicker on the roof and floor than on the side walls.Tertiary dentin, or reparative dentin is formed by replacement odontoblasts in response to moderate-level irritants such as attrition, abrasion, erosion, trauma, moderate-rate dental caries, and some operative procedures. It usually appears as a localized dentin deposit on the wall of the pulp cavity immediately subadjacent to the area of the tooth that has received the injury. *Softer than enamelSusceptible to tooth wear (physical or chemical)Does not have a nerve supply but can be sensitiveIs produced throughout lifeThree classifications PrimarySecondaryTertiaryWill demineralize at a pH of 6.5 and lower

Primary dentin forms the initial shape of the tooth. It is usually completed 3 years after tooth eruption (for permanent teeth). Secondary dentin is deposited after the formation of the primary dentin. Secondary dentin forms on all internal aspects of the pulp cavity, but in the pulp chamber of multirooted teeth it tends to be thicker on the roof and floor than on the side walls.Tertiary dentin, or reparative dentin is formed by replacement odontoblasts in response to moderate-level irritants such as attrition, abrasion, erosion, trauma, moderate-rate dental caries, and some operative procedures. It usually appears as a localized dentin deposit on the wall of the pulp cavity immediately subadjacent to the area of the tooth that has received the injury. *Softer than enamelSusceptible to tooth wear (physical or chemical)Does not have a nerve supply but can be sensitiveIs produced throughout lifeThree classifications PrimarySecondaryTertiaryWill demineralize at a pH of 6.5 and lower

Primary dentin forms the initial shape of the tooth. It is usually completed 3 years after tooth eruption (for permanent teeth). Secondary dentin is deposited after the formation of the primary dentin. Secondary dentin forms on all internal aspects of the pulp cavity, but in the pulp chamber of multirooted teeth it tends to be thicker on the roof and floor than on the side walls.Tertiary dentin, or reparative dentin is formed by replacement odontoblasts in response to moderate-level irritants such as attrition, abrasion, erosion, trauma, moderate-rate dental caries, and some operative procedures. It usually appears as a localized dentin deposit on the wall of the pulp cavity immediately subadjacent to the area of the tooth that has received the injury. **The tubules run parallel to each other in an S-shape course. The tubules are filled with a fluid. External stimuli cause movement of the dentinal fluid, a hydrodynamic movement, which can result in short, sharp pain episodes. These details are important in understanding dentin hypersensitivity.*The tubules run parallel to each other in an S-shape course. The tubules are filled with a fluid. External stimuli cause movement of the dentinal fluid, a hydrodynamic movement, which can result in short, sharp pain episodes. These details are important in understanding dentin hypersensitivity.Associations between erosion and hypersensitivity involve: Open/patent tubulesGreater in numberLarger in diameterRemoval of smear layerErosion/tooth wearUndercalcifiedCementum is:Thin layer of mineralized tissue covering the dentin Softer than enamel and dentinAnchors the tooth to the alveolar bone along with the periodontal ligament Not sensitiveDental pulp is:Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the pulp chamberPulp canals traverse the root of the toothTypically sensitive Dental pulp is:Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the pulp chamberPulp canals traverse the root of the toothTypically sensitive Dental pulp is:Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the pulp chamberPulp canals traverse the root of the toothTypically sensitive The gingival is commonly divided into free (the unattached portion, forming the wall of the gingival crevice) and attached (the part that is firm and resilient and bound to the underlying cementum and the alveolar bone, thus being immovable). Dental pulp is:Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the pulp chamberPulp canals traverse the root of the toothTypically sensitive Dental pulp is:Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the pulp chamberPulp canals traverse the root of the toothTypically sensitive Dental pulp is:Innermost part of the toothA soft tissue rich with blood vessels and nervesResponsible for nourishing the toothThe pulp in the crown of the tooth is known as the pulp chamberPulp canals traverse the root of the toothTypically sensitive The oral environment consists of:PlaqueSaliva pH ValuesDemineralizationRemineralizationPlaque:7,8is a biofilmcontains more than 400 different identified species of bacteria there is harmless and harmful plaquesalivary pellicle allows the bacteria to adhere to the tooth surface, which begins the formation of plaqueSaliva:7,8complex mixture of fluidsperforms protective functions: lubricationaids swallowingmasticationkey role in remineralization of enamel and dentin buffering pH values:7,8measure of acidity or alkalinity of a solution measured on a scale of 1-14pH of 7 indicates that the solution is neutralpH of the mouth is close to neutral until other factors are introducedpH is a factor in demineralization and remineralizationDemineralization:7,8mineral salts dissolve into the surrounding salivary fluid: enamel at approximate pH of 5.5 or lowerdentin at approximate pH of 6.5 or lowererosion or caries can occur Remineralization:pH comes back to neutral (7)saliva-rich calcium and phosphatesminerals penetrate the damaged enamel surface and repair it:enamel pH is above 5.5dentin pH is above 6.5