Dental Nomenclature II RSD 811

Embrasure spaces

Embrasures Negative space that surrounds each contact area when teeth are in contact with each other Serve to direct food away from the gingiva Restorations with improperly formed embrasures create food traps Named for their location Incisal/Occlusal Facial (Labial/Buccal) Lingual Cervical (Interproximal Space)

Embrasures Very helpful when waxing teeth to proper form An area that is over- or under-contoured in wax will affect the size and shape of the embrasure space in the finished restoration Lingual embrasures are larger than facial embrasures When viewed from the occlusal, teeth taper lingually to fit into the arch Cervical embrasures are larger than incisal/occlusal

Embrasures Cervical embrasures are filled with interdental papillae in a healthy mouth

Line angles

Line Angles An arbitrary line formed by the junction of two tooth surfaces (planes) Named for their location

Line Angles

Line Angles

Point Angles Formed by the junction of three tooth surfaces Named for their location

Point Angles

Point Angles

Revisiting Tooth tissues

Tooth Tissues Enamel Hard, acellular (95% calcium hydroxyapatite, 5% water) Formed by ameloblasts Covers the anatomical crown Complete prior to tooth eruption Functions to protect the dentin

Tooth Tissues Enamel Dentin Pulp Cementum Gingiva Alveolus / Alveolar bone Root canal Cementum

Tooth Tissues Dentin Softer than enamel or cementum Forms the major bulk of the tooth Surrounds and protects the pulp cavity Provides general form and elastic strength to the tooth

Tooth Tissues Dentin Formed by odontoblast cells throughout life Primary dentin is formed prior to root completion Secondary dentin formed following root completion

Tooth Tissues Dentin Enamel Pulp Cementum Gingiva Alveolus / Alveolar bone Root canal Cementum

Tooth Tissues Cementum Similar to bone Formed throughout life by cementoblasts Covers the anatomical root Attaches to the periodontal ligament

Tooth Tissues Dental Pulp Connective, lymphatic, nervous and vascular tissue located in the pulp cavity and root canal spaces Supplies nutrition to the tooth Houses the odontoblasts (form 1° and 2° dentin) Responds defensively to injury Provides sensory feedback

Supporting structures The Periodontium Supporting structures

The Periodontium Gingiva Periodontal Ligament Alveolar Bone Enamel Dentin Dental Pulp Gingiva Cementum Periodontal Ligament Alveolar Bone

The Periodontium Surrounds the root of a tooth The Periodontal Ligament (PDL) Surrounds the root of a tooth Forms an elastic attachment of the cementum to the alveolar bone Serves sensory (proprioceptive), nutrient and formative functions

The Periodontium Alveolar bone Forms alveoli and crypts of developing teeth and sockets of erupted teeth Between the roots of adjacent teeth is termed interdental septum Continuous with cortical layer of bone (called lamina dura)

The Periodontium Gingiva Covers the alveolar bone Only tissue of the periodontium that is visible in a healthy mouth

The Periodontium Gingiva Attached Gingiva Directly adjacent to alveolar bone Physically bound to tooth or bone Firm, pink, relatively thick keratinized tissue Resistant to infection and trauma

The Periodontium Gingiva Free Gingiva Coronal to the alveolar bone Not bound to the tooth Creates gingival sulcus

The Periodontium Gingiva Free Gingiva Papillary Gingiva/Interdental Papillae Free gingiva that occupies the interdental space Located below the contact area

The Periodontium Gingiva Free Gingiva Marginal Gingiva Free gingiva located facial and lingual to each tooth Joins the papillary gingiva located interproximally

The Periodontium Alveolar Mucosa Differs in: Mucogingival junction The soft tissue covering located apical to the attached gingiva Mucogingival junction Differs in: Color Thickness Structure Attachment

The Periodontium Alveolar Mucosa

Eruption process and sequence Tooth development

General Information Much of tooth development occurs prior to eruption First primary tooth erupts at 6 months First permanent tooth erupts at 6 years Mandibular teeth typically erupt before maxillary teeth Sequence is usually the same, though actual eruption times vary

Calcification Tooth tissues become hardened by deposit of mineral salts in enamel, dentin, bone and cementum Primary teeth begin to calcify at 4 months in utero Complete at 3-4 years Permanent teeth begin calcification soon after birth Complete at 18-25 years

Calcification

Lobe Formation Tooth formation begins with the crown and continues apically Initiates in 4-5 growth centers (Lobes) Lobes coalesce into crown, then root formation follows Form, contour and arrangement of the lobes determines tooth form

Lobe Formation All anterior teeth and most posterior teeth develop from 4 lobes Anterior teeth and premolars: 3 facial lobes 1-2 lingual lobes Molars: 2 facial lobes 2-3 lingual lobes

Lobe Formation 1 2 3 5 5 4 Mandibular first molar Maxillary first molar (with Cusp of Carabelli) Mandibular second premolar (in some cases)

Lobe Formation Anterior Teeth Mammelon – a rounded protuberance found on the incisal ridges of newly erupted incisors Suggest the location of the three facial lobes Mesiofacial Central facial Distofacial Wear away over time

Lobe Formation Anterior Teeth Cingulum – a lingual lobe of an anterior tooth making up most of the cervical 1/3 of the lingual surface

Eruption The penetration of oral mucosa as a tooth enters the oral cavity At the time of eruption, the crown is fully developed (calcification is complete) while the root is approximately 2/3 complete The eruption process is aided by: Development of the root which forces further eruption Bone growth at the base of the alveolus

Eruption Sequence: Primary Dentition Centrals: 6 months-1 year Laterals: 9 months-16 months 1st Molars: 1-1.5 years Canines: 1.5-2 years 2nd Molars: 2-3 years

Eruption Sequence: Permanent Dentition Mand 1st Molar: 6 years Mand Centrals: 6 years Mand Laterals: 7 years Mand Canine: 10 years Mand 1st PM: 10 years Mand 2nd PM: 11 years Mand 2nd Molars: 12 years Mand 3rd Molars: 20 years Max 1st Molar: 6 years Max Centrals: 7 years Max Laterals: 8 years Max 1st PM: 10 years Max 2nd PM: 11 years Max Canine: 11 years Max 2nd Molars: 12 years Max 3rd Molars: 20 years

Eruption Sequence: Permanent Dentition

Primary Root Resorption Allows development and eruption of the permanent teeth Results from pressure atrophy from the crowns of succedaneous teeth

Primary Root Resorption Nonsuccedaneous teeth do not replace existing primary teeth Permanent molars

Extrusion Active eruption due to loss of the antagonist When a tooth erupts into contact with its antagonist, further active eruption is halted. It may continue later due to occlusal wear or loss of an opposing tooth

Active Eruption The process of actual bodily movement of the tooth relative to the tissues of the jaw Attrition – the wearing away of the functioning surfaces of teeth due to use

Passive Eruption Recession of the periodontium resulting in a longer clinical crown

Summary: Life of a Tooth Development from lobes Lobes coalesce Root formation Active eruption and continued root formation Attrition Active Eruption Passive Eruption