Class Notes (838,596)
Canada (510,980)
ANAT 261 (42)
Lecture

10. Tooth and Tooth Development.pdf

6 Pages
146 Views
Unlock Document

Department
Anatomy & Cell Biology
Course
ANAT 261
Professor
Craig Mandato
Semester
Fall

Description
DIHYODONTY Right Quadrant Left Quadrant 2 Dental Arches Upper (Maxillary) Lower (Mandibular) Wisdom tooth (17 years old) Central Lateral Canines Premolars Molars Incisors Incisors Baby (20 Teeth) Adult (32 Teeth Enainel (En) Erupted Tooth CLINICAL CROWN ANATOMICAL Dentin D) Gingiva (cuticle) gingival J MJ Pulp (P) odontoblast (O Alveolar Bone (ALB) ROOT Periodontal Ligament (PL) Cementum (C), contains Cementocytes J Apical Foramen (AF) DIHYODONTY Right Quadrant Left Quadrant 2 Dental Arches Upper (Maxillary) Lower (Mandibular) Wisdom tooth (17 years old) Central Lateral Canines Premolars Molars Incisors Incisors Baby (20 Teeth) Adult (32 Teeth Enainel (En) Erupted Tooth CLINICAL CROWN ANATOMICAL Dentin D) Gingiva (cuticle) gingival J MJ Pulp (P) odontoblast (O Alveolar Bone (ALB) ROOT Periodontal Ligament (PL) Cementum (C), contains Cementocytes J Apical Foramen (AF)Naveen Sooknanan McGill Fall 2011 Tooth and Tooth Development: As we said before, the gingiva (which are your gums) are made of a stratified squamous parakeratinized epithelium  The parakeratin allows the gingiva to be tough, but still be moist  The toughness helps your gums hold up to constant abrasion while the moistness lubricates the food and your mouth The first step of digestion is the mouth, where food gets mashed up by the teeth into small fragments which can be easily broken down  Amylase, which is secreted into saliva, starts digestion of carbohydrates Humans have 2 sets of teeth, consisting of two dental arches (upper and lower)  The upper arch is known as the maxillary arch while the power arch is known as the mandibular arch  Each arch can be divided into quadrants, left and right. These quadrants are mirror images of each other. This situation is known as dihydonty  Babies have deciduous dentition (baby teeth) consisting of 20 teeth and adults have permanent dentition consisting of 32 teeth  There are 5 types of teeth (these values are per QUADRANT, from middle to edge): o Central incisors: babies have 1, adults have 1 o Lateral incisors: babies have 1, adults have 1 o Canines: babies have none, adults have 1 o Premolars: babies have 0, adults have 2 o Molars: babies have 2, adults have 3  The last molar on each quadrant is a wisdom tooth, which comes in around 17 years of age  Evolution has caused the human jaw to shrink in size, and wisdom teeth have to often be removed to make room for other teeth to grow properly o This makes a total of 20 teeth in babies, 32 in adults  I.e. multiply total values by 4 because they are per 1Naveen Sooknanan McGill Fall 2011 quadrant The structure of the tooth contains the tooth itself and the surrounding gingiva:  The clinical crown is the visible part of the tooth coming out of the gingiva o The first layer is the enamel (En), which will never be seen in slides because it is removed during fixation by decalcification (just like bone) o Under the enamel lies a layer of dentin D), which is very eosinophilic, staining very pink in slides o The layer under the dentin is known as the predentin, which is not mature and only made of collagen  The anatomical crown includes the clinical crown, as well as the gingiva and the dentin- enamel junction (where they meet) o The gingiva is a parakeratinized squamous stratified epithelium  There is no visible peeling of the gingiva (unlike skin which is orthokeratininzed) o The dentin-enamel junction is where the enamel joins up with the cementum (a layer below the dentin)  The root consists of all structures below the anatomical crown o The mucogingival junction (MJ) is where the transition between parakeratinized and non-keratinized epithelium occurs o The pulp (P) is the central region of the tooth  It contains loose CT with plenty of BVs and nerves which synapse with odontoblasts, which secrete dentin  The pulp degenerates with age, making it harder to perform root canals on elderly patients o Odontoblasts (O) line the outer edge of the pulp and secrete dentin into the dentin matrix  Odontoblasts are actually modified neurons, which is why it hurts when you chip your tooth  Each odontoblast has one canaliculus of dentin which travels all the way to the cementum. All of these odontoblasts secrete the dentin matrix o The alveolar bone (ALB) is what creates the dental cavity which the tooth sits in  It is not actually a part of the tooth  There are no Haversian systems in the alveolar bone, but there are osteocytes within the ECM o The periodontal ligament (PL) is a layer of dense irreg. CT which anchors the tooth to the alveolar bone  They provide rigidity but still allow slight flexibility  The CT contains fibrocytes/blasts and collagen fibers, which anchor the alveolar bone to the cementum, which is a layer lining the dentin  Plaques and bacteria can degrade the dentin, and can cause inflammation is they reach the PL  The alveolar bone will recede and the tooth will become loose if the infection is not dealt with quickly o The cementum (C) is a layer of cells called cementocytes, which are very similar to osteocytes 2Dentin Dentin Periodontal Ligament Cementum Alveolar Bone Dentin Gingiva kera La Alveolar Bone Slide 19 Pulp Odontoblasts Dentin Pre-dentin Dentin Dentin Periodontal Ligament Cementum Alveolar Bone Dentin Gingiva kera La Alveolar Bone Slide 19 Pulp Odontoblasts Dentin Pre-dentinNaveen Sooknanan McGill Fall 2011  They get stuck in the ECM  This layer thickens at the bottom of the tooth, near the apical foramen (which we will see next) o The apical foramen (AF), is the opening of the pulp into the PL The main components on the other layer of the tooth are enamel and dentin, both of which are solid materials made partially of inorganic materials  Enamel, the hardest material in the body, is made up of 99% inorganic matrix. which consists of hydroxyapatite crystals, Ca (PO ) (10) 4 6 2 o The other 1% is made of proteins such as enamelins and amelogenins, and water  Dentin is made of 70% inorganic matrix, again made of hydroxyapatite crystals o The 30% organic matrix consist of proteins, proteoglycans and collagen type I (similar to bone)  The layer of enamel has to be removed by decalcification before the tooth can be cut o This can be done by 5% nitric acid (not allowed anymore because it’s dangerous) or a 250mmol EDTA solution o The reason dentin can be seen is because the 30% organic matrix is left behind, appearing as a pale pink. Enamel only has 1% organic material Erupted Tooth (top) Space where enamel used to be
More Less

Related notes for ANAT 261

Log In


OR

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


OR

By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.


Submit