Anatomy Lab Week 2 PDF

9/8/24 Review- Case 1 A 62-year-old male presents to the dental office you are working at. He is a patient of record but has not been to the office in 4 y...

9/8/24 Review- Case 1 A 62-year-old male presents to the dental office you are working at. He is a patient of record but has not been to the office in 4 years. He is concerned about the appearance of his lower lip “why does my lip look like it is disappearing?”. He is a fisherman who has a history of cancer (basal carcinoma) on the tip of his nose. The dentist notices loss of the vermillion border. © 2016, Southern Alberta Institute of Technology 1 Review- Case 1 (Courtesy of Margaret J. Fehrenbach, RDH, MS.) Solar Damage Figure 1.8. In Fehrenbach,M.J. & Popowics, T: Illustrated embryology, histology, and anatomy, ed 5. : 2020. Elsevier. © 2016, Southern Alberta Institute of Technology 2 Review- Case 1 1. What is the vermillion border? 2. What do you think may cause the loss of the vermillion border © 2016, Southern Alberta Institute of Technology 3 1  9/8/24 Review – Case 2 A new patient presents to the dental office you are working at and is scheduled for a full examination. She is female and 32 years of age. She was last a t a dental office 2 years ago. She is concerned about the floor of her mouth. She wonders “What are the hard bumps on the (Courtesy of Margaret J. Fehrenbach, RDH, MS.) Photo of open mouth, entitled Figure 2-8, bottom of my mouth?” displaying the area under the tongue.. In Fehrenbach,M.J. & Popowics, T: Illustrated embryology, histology, and anatomy, ed 5. : 2020. Elsevier. 4 Review- Case 2 1. What are the bony growths on the floor of this patient’s mouth? 2. Where are they usually located? © 2016, Southern Alberta Institute of Technology 5 Primary Teeth Outcome 5: Identify anatomical landmarks of primary teeth. 6 2  9/8/24 Characteristics 5.1 Identify each tooth in the primary dentition according to location, eruption date and anatomical features. 7 Dentition Periods Although there are only two sets of teeth, there are three dentition periods ◦ Primary ◦ Mixed ◦ Permanent © 2016, Southern Alberta Institute of Technology 8 Primary Dentition The first set of 20 primary teeth is called the primary dentition This dentition is commonly referred to as the “baby teeth” You may also hear the term deciduous dentition, an older and less frequently used dental term to describe the primary dentition © 2016, Southern Alberta Institute of Technology 9 3  9/8/24 Primary Dentition There are 20 primary teeth: 10 in the maxillary arch and 10 in the mandibular arch Includes incisors, canines, and molars Numbered in the FDI System by quadrants (5-8) © 2016, Southern Alberta Institute of Technology 10 10 Primary Dentition E (51) F (61) D (52) G (62) C (53) H (63) Incisors Canine B (54) I (64) Molars A (55) MAXILLARY ARCH J (65) RIGHT LEFT MANDIBULAR ARCH T (85) K (75) Molars S (84) Canine L (74) Incisors R (83) M (73) Q (82) N (72) P (81) O (71) Figure 15-1 From Fehrenbach,M.J. & Popowics, T: Illustrated embryology,©histology, Elsevier Collection. and anatomy, ed 4, Maryland Heights, MO: 2016, Elsevier.), histology © 2016, Southern Alberta Institute of Technology 11 Mixed Dentition Mixed dentition generally occurs between the ages of 6 and 12 years Both primary and permanent teeth are present during this transitional period The mixed dentition period begins with the eruption of the first permanent tooth, which is a permanent mandibular first molar This period ends with shedding of the last primary tooth © 2016, Southern Alberta Institute of Technology 12 4  9/8/24 Mixed Dentition Period From Bird D.L. & Robinson D.S: Modern © 2016, dental assisting, Southern ed 12, 2018, Alberta Institute Saunders/Elsevier.), histology, and anatomy, ed 4, St of Technology Louis, 2016, Saunders. 13 Mixed Dentition From Fehrenbach,M.J. & Popowics, T: Illustrated embryology, histology, and anatomy, ed 4, Maryland Heights, MO: 2016, Elsevier.), histology © 2016, Southern Alberta Institute of Technology 14 Permanent Dentition The final, or adult, dentition This period begins with shedding of the last primary tooth Growth of the jawbones slows and eventually stops There is very little growth of the jaw overall during this period because puberty has passed (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 15 5  9/8/24 Primary Teeth Eruption The actual dates are not as important as the eruption sequence, because there can be a great deal of variation 3 2 in the actual dates of 9 4 6 4 1 eruption. 8 5 7 However, the sequence tends to be uniform From Fehrenbach,M.J. & Popowics, T: Illustrated embryology, histology, and anatomy, ed 4, 2016, Elsevier.), histology 16 Primary Teeth Development The primary dentition PRENATAL PRIMARY DENTITION EARLY CHILDHOOD (preschool age) takes between 2 and 3 5 months in utero 2 years (± 6 months) 7 months in utero years to be completed INFANCY Birth 3 years (± 6 months) 6 months (± 2 months) 4 years (± 9 months) 9 months (± 2 months) 5 years 1 year (± 9 months) (± 3 months) 18 months 6 years (± 3 months) (± 9 months) A (All data from Nelson S: Wheeler’s dental anatomy, physiology and occlusions, ed 10, Philadelphia, 2015, Saunders/Elsevier.) 17 17 Primary Teeth Development Oral epithelium Successional dental lamina (cut to show Posterior extension of dental lamina of permanent teeth primordia tooth buds) Tooth germs of nonsuccedaneous permanent molars Developing Base of the tongue mandibular dental arch Vestibule Body of the tongue Developing primary teeth Developing mandible From Fehrenbach,M.J. & Popowics, T: Illustrated embryology, histology, and anatomy, ed 4, 2016, Elsevier.), histology © 2016, Southern Alberta Institute of Technology 18 6  9/8/24 Anatomical Features 5.2 Compare the anatomical features of deciduous teeth to their permanent counterparts. 19 Primary to Permanent Comparison The crown of any Whiter primary tooth is short Yellower crown crown color Primary color Permanent Smaller in relation to its total overall size Prominent Larger overall size length cervical ridge Narrower Wider roots roots It is also narrower, at the cementoenamel Figure 18-4 junction (CEJ), making From Illustrated dental embryology, histology and anatomy. 4th ed. by Fehrenbach, M. J. & Popowics, T. (2016) Maryland them appear bulbous Heights, MO. Elsevier. (Bird & Robinson, 2021). (Courtesy of Margaret J. Fehrenbach, RDH, MS.) 20 20 Primary to Permanent Comparison ˜ Primary teeth are smaller overall than permanent teeth (Bird & Robinson, 2021). Labial Views Mesial Views Cementoenamel CEJ Root junction Root Cementoenamel junction CEJ Crown Crown Primary Maxillary Permanent Maxillary Primary Maxillary Permanent Maxillary First Molar First Molar Central Incisor Central Incisor Figure 18-2 Figure 18-3 From Illustrated dental embryology, histology and From Illustrated dental embryology, histology and anatomy. 4th ed. anatomy. 4th ed. by Fehrenbach, M. J. & Popowics, T. by Fehrenbach, M. J. & Popowics, T. (2016) Maryland Heights, MO. (2016) Maryland Heights, MO. Elsevier. Elsevier. 21 21 7  9/8/24 Primary to Permanent Comparison Roots of primary teeth are also narrower and Whiter crown color Primary Yellower crown longer than the crown Permanent color Smaller overall Larger length. size overall size Prominent cervical ridge Wider Each crown-to-root Narrower roots roots ratio of primary teeth is smaller than those Figure 18-4 From Illustrated dental embryology, histology and anatomy. 4th ratios of their ed. by Fehrenbach, M. J. & Popowics, T. (2016) Maryland Heights, MO. Elsevier. permanent dentition counterparts (Bird & (Courtesy of Margaret J. Fehrenbach, RDH, MS.) Robinson, 2021). 22 22 Primary to Permanent Comparison The enamel is relatively Mesiodistal Section thinner (Bird & Pulp horns Enamel Pulp horns Dentin Robinson, 2021). Pulp cavity Primary Mandibular First Molar Permanent Mandibular First Molar Figure 18-5 From Illustrated dental embryology, histology and anatomy. 4th ed. by Fehrenbach, M. J. & Popowics, T. (2016) Maryland Heights, MO. Elsevier. 23 23 Primary to Permanent Comparison The pulp chambers and Mesiodistal Section Pulp horns Enamel pulp horns are Pulp horns Dentin relatively large in Pulp cavity proportion to those of the permanent teeth (Bird & Robinson, 2021) Primary Mandibular First Molar Permanent Mandibular First Molar Figure 18-5 From Illustrated dental embryology, histology and anatomy. 4th ed. by Fehrenbach, M. J. & Popowics, T. (2016) Maryland Heights, MO. Elsevier. 24 24 8  9/8/24 Primary to Permanent Comparison (From Darby ML, Walsh M: Dental hygiene: theory and practice, ed 2, St Louis, 2003, Mosby/Elsevier.) Which ones are primary and which ones are permanent? © 2016, Southern Alberta Institute of Technology 25 25 Primate Spaces Spaces between the primary maxillary lateral incisor and canine, and also between the primary mandibular canine and first molar (Fehrenbach & Popowics, 2020). (From Bird DL, (From Bird D.L. & Robinson D.S: Modern dental assisting, ed 11, St Louis, 2015, Saunders/Elsevier.) Robinson DS: Modern dental assisting, ed 11, St Louis, 2015, Saunders/Elsevier.) Figure 18-1 26 26 Arch Development: Leeway Space This difference in size, MD between the two types of teeth, is called the leeway space (Fehrenbach & Popowics, 2020) Figure 20-3 From Illustrated dental embryology, histology and anatomy. 4th ed. by Fehrenbach, M. J. & Popowics, T. (2016) Maryland Heights, MO. Elsevier. (Courtesy of Margaret J. Fehrenbach, RDH, MS.) 27 27 9  9/8/24 Functions 5.3 Describe the function of primary teeth 28 Why are primary teeth important? © 2016, Southern Alberta Institute of Technology 29 Clinical Considerations with Primary Teeth Often parents do not understand the importance of the primary teeth Primary teeth hold the eruption space for the permanent teeth Because the enamel and dentin are thinner in primary teeth, decay can travel quickly through the enamel to the pulp, possibly causing loss of the tooth Early dental health education and dental care are essential in keeping the primary dentition (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 30 30 10  9/8/24 Learning Check Usually, the first primary tooth to erupt is the: a. Maxillary central incisor b. Mandibular central incisor c. Maxillary cuspid d. Mandibular first molar © 2016, Southern Alberta Institute of Technology 31 Learning Check The period of mixed dentition exists: a. when the third molars erupt b. before the eruption of the permanent incisors c. before the age of 6 d. after the age of 12 e. none of the above © 2016, Southern Alberta Institute of Technology 33 Learning Check Primary incisors differ from their permanent successors in that the primary incisors: a. have longer roots b. have no pulp canals c. have no mamelons d. enamel is much thicker © 2016, Southern Alberta Institute of Technology 35 11  9/8/24 Learning Check A 7-year-old enters the office with only six permanent teeth. Which of the following is most likely true? a. four of the permanent teeth are incisors b. the child has delayed eruption c. two permanent teeth have been extracted d. four of the permanent teeth are first molars e. three of the permanent teeth are maxillary and three are mandibular. © 2016, Southern Alberta Institute of Technology 37 Permanent Dentition Outcome 6: Identify anatomical landmarks of permanent teeth. 39 Tooth Morphology There is a certain amount of variation among individual teeth, and every tooth may not meet all criteria for identification By understanding the characteristics of each tooth, you will be able to differentiate among teeth, as well as between the left teeth and the right teeth in any particular group © 2016, Southern Alberta Institute of Technology 40 12  9/8/24 41 Anterior Teeth: Permanent Dentition 6.1 Identify each anterior tooth in the permanent dentition according to the location, eruption date, function and identifying features. 41 Anterior Permanent Dentition There are 12 anterior teeth in the permanent dentition, six in each dental arch The permanent anterior teeth include the central incisors, lateral incisors, and canines The central incisors are closest to the midline, the lateral incisors are the second teeth from the midline, and the canines are the third teeth from the midline All anterior teeth are succedaneous, replacing primary teeth of the same type © 2016, Southern Alberta Institute of Technology 42 42 Characteristics of Permanent Anterior Teeth All anterior teeth have a cingulum, a rounded, raised area on the cervical third of the lingual surface The lingual surface on anterior teeth has rounded, raised borders on the mesial and distal surfaces called marginal ridges Some anterior teeth have a fossa, which is a wide, shallow depression on the lingual surfaces (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 43 43 13  9/8/24 Permanent Incisors There are eight permanent incisors ◦ Four maxillary ◦ Four mandibular The maxillary group comprises two central incisors and two lateral incisors, as does the mandibular group These teeth complement each other in form and function The central incisors erupt about a year or so before the lateral incisors do © 2016, Southern Alberta Institute of Technology 44 44 Maxillary Central Incisors (Slide 1 of 2) Maxillary central incisors (1.1 and 2.1) have unique anatomical features Larger in all dimensions, especially mesiodistally, than a permanent mandibular central incisor Root is short compared with the roots of other permanent maxillary teeth All lingual surface features, including the marginal ridges, lingual fossa, and cingulum, are more prominent on the maxillary central incisor than on the mandibular central incisor (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 45 45 Maxillary Central Incisors (Slide 2 of 2) The incisal edge is also known as the incisal surface or incisal plane When newly erupted, the central and lateral incisors have three mamelons, or rounded enamel extensions on the incisal ridge, or edge The mamelons usually undergo attrition shortly after eruption © 2016, Southern Alberta Institute of Technology 46 46 14  9/8/24 Maxillary Central Incisor From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), © 2016, Southern Alberta Institutehistology of Technology 47 Maxillary Lateral Incisors (Slide 1 of 2) The maxillary lateral incisors (1.2 and 2.2) are smaller than the central incisors in all dimensions except root length They usually erupt after the maxillary central incisors The crown of a maxillary lateral incisor has a single root that is relatively smooth and straight but may curve slightly distally Recognizing this feature is helpful in the mounting of radiographs (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 48 48 Maxillary Lateral Incisors (Slide 2 of 2) The lateral incisors vary in form more than any other tooth in the mouth, except the third molars, and are often congenitally missing Because of the variations in form, the permanent maxillary lateral incisors present challenges during preventive, restorative, and orthodontic procedures Open contacts (spaces between teeth), called diastema, often occur in this area because of the variations in tooth size and position in the arch (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 49 49 15  9/8/24 Maxillary Right Lateral Incisor From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, © 2016, Southern Alberta Institute of Technology 2018, Saunders/Elsevier.), histology 50 Pegged Maxillary Lateral Incisor From Ibsen OC, Phelan JA: Oral pathology for the dental hygienist, ed 6, St Louis, 2014, Saunders. © 2016, Southern Alberta Institute of Technology 51 Mandibular Incisors The permanent mandibular incisors are the smallest teeth of the permanent dentition and the most symmetric The central and lateral incisors of the mandibular arch resemble each other Generally, the lateral incisor is larger than the central incisor, in contrast to the teeth in the maxillary arch Supragingival tooth deposits, such as plaque, calculus, and stain, tend to collect in the lingual concavity of the mandibular incisors (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 52 52 16  9/8/24 Mandibular Central Incisors The mandibular central incisors (3.1 and 4.1) are the smallest and simplest teeth and are bilaterally symmetric Each has a small centered cingulum, subtle lingual fossa, and equally subtle marginal ridges The crown of a mandibular central incisor is narrower on the lingual surface than on the labial surface Developmental horizontal lines on anterior teeth, or imbrication lines, and developmental depressions usually not present or very faint (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 53 53 Mandibular Right Central Incisor From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), © 2016, Southern Alberta Institute of Technology histology 54 Mandibular Lateral Incisors The mandibular lateral incisors (3.2 and 4.2) are slightly larger than the mandibular central incisors but otherwise similar to them The lateral teeth usually erupt after the mandibular central incisors The lateral incisors have a small, distally placed cingulum Greater height of the cementoenamel junction (CEJ) curvature on the mesial surface than on the distal surface helps distinguish the right mandibular lateral incisor from the left incisor (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 55 55 17  9/8/24 Mandibular Right Lateral Incisor From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, © 2016, Southern Alberta Institute of Technology Saunders/Elsevier.), histology 56 Permanent Canines (Slide 1 of 2) The permanent canines are the four anterior teeth located at the corner of each quadrant for each dental arch © 2016, Southern Alberta Institute of Technology 57 57 Permanent Canines (Slide 2 of 2) The permanent canines are the longest teeth in the dentition The root is usually the length of the crown This large root is externally manifested by the bony vertical ridge called the canine eminence (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 58 58 18  9/8/24 Maxillary Canines The maxillary canines (1.3 and 2.3) usually erupt after the mandibular canines, after the maxillary incisors, and possibly after the maxillary premolars The cusp tip is sharper on a maxillary canine The mesial cusp slope is usually shorter than the distal cusp slope in both the maxillary and the mandibular canines when they first erupt The length of these cusp slopes, and the cusp tip can change with attrition (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 59 59 Mandibular Canines The mandibular canines (3.3 and 4.3) usually erupt before the maxillary canines and after most of the incisors have erupted A mandibular canine closely resembles a maxillary canine Although the entire tooth is usually as long, a mandibular canine is narrower labiolingually and mesiodistally than a maxillary canine The lingual surface of the crown of the mandibular canines is smoother than that of the maxillary canines and has a less developed cingulum and two marginal ridges (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 60 60 Canines From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 61 19  9/8/24 Clinical Considerations with Canines The maxillary canines may erupt labially or lingually in relation to the surrounding teeth The maxillary canines may also fail to erupt fully and may remain impacted This occurs because the permanent maxillary canines erupt after the maxillary incisors and possibly after the premolars and their arch spaces have closed (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 62 62 Permanent Dentition: Posterior Teeth 6.2 Identify each posterior tooth in the permanent dentition according to the location, eruption date, function, and identifying features. 63 Posterior Permanent Dentition (Slide 1 of 2) The permanent posterior teeth include the premolars and molars The crown of each posterior tooth has an occlusal surface, bordered distally and mesially by marginal ridges The occlusal surfaces have two or more cusps Imagine each cusp as a mountain with sloping areas, or cusp ridges, extending from the top of the mountain; between the ridges are sloping areas called inclined cuspal planes (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 64 64 20  9/8/24 Posterior Permanent Dentition (Slide 2 of 2) Each shallow, wide depression on the occlusal table is a fossa One type of fossa on posterior teeth, the central fossa, is located where the cusp ridges converge in a central point, where the grooves meet Another type of fossa is the triangular fossa Sometimes located in the deepest portions of the fossa are occlusal developmental pits ◦ Each pit is a sharp pinpoint depression where two or more grooves meet (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 65 65 Permanent Premolars There are eight premolars in the permanent dentition, two in each quadrant They are located posterior to the canines and immediately anterior to the molars There are two types of premolars ◦ First ◦ Second © 2016, Southern Alberta Institute of Technology 66 66 Maxillary First Premolars (Slide 1 of 2) A maxillary first premolar (1.4 and 2.4) is larger than a maxillary second premolar Each maxillary first premolar has two cusps (buccal and lingual) and two roots (facial and lingual) Both maxillary premolars erupt earlier than the mandibular premolars (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 67 67 21  9/8/24 Maxillary First Premolars (Slide 2 of 2) The maxillary first premolar has a bifurcated root (two roots: one buccal and one lingual) Some first premolars have roots that are joined, or fused The roots are shorter in length and resemble the roots of the molars (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 68 68 Maxillary First Premolar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, © 2016, Southern Alberta Institute of Technology Saunders/Elsevier.), histology 69 Maxillary Second Premolars Each maxillary second premolar (1.5 and 2.5) has two cusps (buccal and lingual) and one root (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 70 70 22  9/8/24 Differences Between Second and First Maxillary Premolars The cusps are closer in length on the second premolar The lingual cusp is slightly shorter, but not as short as the cusp on the maxillary first premolar The mesiobuccal cusp slope is shorter than the distobuccal cusp slope on the second premolar The cusps of the secondary premolar are not as sharp as those of the maxillary first premolar The second premolar has only one root and one root canal The second premolar is wider buccolingually than mesiodistally (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 71 71 Mandibular First Premolars Each mandibular first premolar (3.4 and 4.4) has a long and well-formed buccal cusp and a small, nonfunctioning lingual cusp The lingual cusp may be no larger than the cingulum on some maxillary canines The mandibular first premolars are smaller and shorter than the mandibular second premolars (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 72 72 Mandibular Right First Premolar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 73 23  9/8/24 Mandibular Second Premolars The permanent mandibular second premolars (3.5 and 4.5) erupt distal to the mandibular first premolars They are the succedaneous replacements for the primary mandibular second molars There are two forms of the mandibular second premolar ◦ Three-cusp type, or tricuspidate form ◦ Two-cusp type, or bicuspidate form (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 74 74 Mandibular Second Premolar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, © 2016, Southern Alberta Institute of Technology Saunders/Elsevier.), histology 75 Mandibular Second Premolar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 76 24  9/8/24 Clinical Considerations with Premolars The maxillary and mandibular premolars work with the molars in the chewing of food The first premolars help the canines in shearing or cutting bits of food The premolars also support the corners of the mouth and cheeks (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 77 77 Permanent Molars (Slide 1 of 2) There are 12 molars, three in each quadrant, in the permanent dentition The molar crowns have four or five short, blunt cusps, and each molar has two or three roots that help support the larger crown © 2016, Southern Alberta Institute of Technology 78 78 Permanent Molars (Slide 2 of 2) There are three types of molars: First, second, and third The first and second molars are also called the 6- year and 12-year molars because of the approximate ages at which they erupt © 2016, Southern Alberta Institute of Technology 79 79 25  9/8/24 Maxillary Molars Usually, the first permanent teeth to erupt into the maxillary arch Each maxillary molar usually has four major cusps, with two on the buccal portion of the occlusal table and two on the lingual Each maxillary molar has three well-separated and well-developed roots A tooth with three roots is said to be trifurcated, which means “divided into thirds” (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 80 80 Maxillary First Molars The maxillary first molars (1.6 and 2.6) are the first permanent teeth to erupt into the maxillary arch They erupt distal to the primary maxillary second molars and are therefore nonsuccedaneous (do not replace the primary teeth) The maxillary first molar is the largest tooth in the maxillary arch and also has the largest crown in the permanent dentition This molar is composed of five developmental lobes, two buccal and three lingual The fifth cusp is called the cusp of Carabelli (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 81 81 Maxillary Right First Molar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 82 26  9/8/24 Maxillary Second Molars The crown of the maxillary second molar (1.7 and 2.7) is somewhat shorter than that of the first molar, and it usually has four cusps No fifth cusp is present There are three roots The roots of the secondary molars are smaller than those of the first molars ◦ The lingual root is still the largest and longest (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 83 83 Maxillary Right Second Molar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 84 Maxillary Third Molars The maxillary third molars (1.8 and 2.8) differ considerably in size and contour The crown of the maxillary third molar is smaller and the roots are usually shorter The roots of the maxillary third molar tend to fuse, and the result is a single tapered root People sometimes refer to the maxillary third molars as the “wisdom” teeth because they erupt last (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 85 85 27  9/8/24 Clinical Considerations with Maxillary Molars The roots of the maxillary molars may penetrate the maxillary sinus as a result of accidental trauma or during an extraction The permanent maxillary third molars may fail to erupt and may remain impacted within the alveolar bone If the maxillary first molar is lost, the second molar can tip and drift into the open space, causing difficulty in chewing and furthering periodontal disease (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 86 86 Buccal Views of Maxillary Right Molars From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 87 Mandibular Molars (Slide 1 of 2) The mandibular molars erupt 6 months to 1 year before the corresponding permanent maxillary molars The crowns of the mandibular molars have four or five major cusps, with two lingual cusps always of about the same width All mandibular molars are wider mesiodistally than buccolingually, similar to anterior teeth (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 88 88 28  9/8/24 Mandibular Molars (Slide 2 of 2) Each mandibular molar has two well-developed roots, one mesial and one distal A tooth with two roots is referred to as bifurcated, which means “divided into two” A bifurcation is the area at which the two roots divide (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 89 89 Mandibular First Molars The permanent mandibular first molars (3.6 and 4.6) erupt between 6 and 7 years of age These teeth are commonly the first permanent teeth to erupt in the oral cavity The two roots, mesial and distal, of a mandibular first molar are larger and more divergent than those of a second molar (Bird & Robinson, 2021) 5 cusps: MB, DB, D, ML and DL Two facial (buccal) developmental grooves which may end in pits. © 2016, Southern Alberta Institute of Technology 90 90 Mandibular Right First Molar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 91 29  9/8/24 Mandibular Second Molars The mandibular second molars (3.7 and 4.7) erupt between 11 and 12 years of age These teeth erupt distal to the permanent first molars and therefore are nonsuccedaneous The crown of the mandibular second molar is slightly smaller than that of the first molar in all directions The crown has four well-developed cusps (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 92 92 Mandibular Right Second Molar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 93 Mandibular Third Molars The mandibular third molars (3.8 and 4.8) are similar to the maxillary third molars in that they vary greatly in shape There is no typical mandibular third molar This molar is usually smaller in all dimensions than the second molar The third molar consists of four developmental lobes A mandibular third molar has two roots that are fused, irregularly curved, and shorter than those of a mandibular second molar (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 94 94 30  9/8/24 Mandibular Right Third Molar From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 95 Clinical Considerations with Mandibular Molars The lingual inclination of the crowns of the mandibular molars can make it difficult to position the oral evacuator The lingual inclination of the molar teeth can also pose problems in oral hygiene for patients, who may miss the lingual gingiva with the toothbrush (Bird & Robinson, 2021) © 2016, Southern Alberta Institute of Technology 96 96 Mandibular Right Molars From Bird D.L. & Robinson D.S: Modern dental assisting, ed 12, St Louis, 2018, Saunders/Elsevier.), histology © 2016, Southern Alberta Institute of Technology 97 31  9/8/24 Eruption Dates Make sure that you are aware of dates (ranges) © 2016, Southern Alberta Institute of Technology 98 Next Class Outcome 5 5.4 Describe the occlusion of the primary dentition. Outcome 6 6.3 Define terms pertaining to the occlusion of the permanent dentition. 6.4 Identify Angle's Classification of Occlusion. Assignment 1 – Due Oct 1 © 2016, Southern Alberta Institute of Technology 99 References Bird, D.L & Robinson, D.S. (2021). Modern dental assisting (13th ed.). Elsevier Bird, D.L & Robinson, D.S. (2018). Modern dental assisting (12th ed.). Elsevier Feherenbach, M.J. & Popowics, T. (2020). Illustrated dental embryology, histology and anatomy (5th ed.).Elsevier Feherenbach, M.J. &Popowics, T. (2016). Illustrated dental embryology, histology and anatomy (4th ed.). Elsevier © 2016, Southern Alberta Institute of Technology 100 32