Oral Embryology Workbook PDF

**Oral Embryology** **Biomedical Sciences, Year 1** Diagram Description automatically generated **Image source: Thesleff 2014** **Student name:** **Mohammed Haroon Tariq** **\ ** **INTRODUCTION** Use this workbook to support your **self-directed study**, reading and learning for the content...

**Oral Embryology** **Biomedical Sciences, Year 1** Diagram Description automatically generated **Image source: Thesleff 2014** **Student name:** **Mohammed Haroon Tariq** **\ ** **INTRODUCTION** Use this workbook to support your **self-directed study**, reading and learning for the content covered in the lectures on Oral Embryology. Answers will not be provided, refer to the lecture materials, reading and resources to find the answers. It is not essential to complete. Bring your questions to the consolidation session. **Lecture series, Workbook questions and Glossary of Terms**: +-----------------------------------+-----------------------------------+ | **Lectures** | **Questions** | +===================================+===================================+ | 1. Embryology of the head, face | 1-4 | | and oral cavity | | +-----------------------------------+-----------------------------------+ | 2. Embryology of the oral | 5-7 | | tissues | | +-----------------------------------+-----------------------------------+ | 3. Embryology of the crown | 8-15 | +-----------------------------------+-----------------------------------+ | 4. Embryology of the root | 16-23 | +-----------------------------------+-----------------------------------+ | 5. Embryology of eruption and | 24-31 | | exfoliation | | +-----------------------------------+-----------------------------------+ | 6. Consolidation session | See Moodle | +-----------------------------------+-----------------------------------+ | 7. Glossary of terms | End of document | +-----------------------------------+-----------------------------------+ **READING and RESOURCES:** **Textbook Reading**: - **Chapter 1, 5, 9, 10** of: Nanci, A. & Ten Cate, A.R., 2018. ***Ten Cate\'s oral histology : development, structure, and function.*** 9th edition / Antonio Nanci, PhD (McGill), PhD Honoris cause (University of Messina). - **Chapter 21, 22, 23, 24** of: Berkovitz, B. K. B., Holland, G. R., & Moxham, B. J. (2018). ***Oral anatomy, histology and embryology,** 5^th^ Ed*. Edinburgh: Mosby/Elsevier. **Resources Online:** - **Atlas of tooth development and eruption** -- useful guide to tooth development timeline: - **Digital laboratory oral histology**, slides 16-40 - **University of Michigan virtual laboratory** - **Easy to follow descriptions and diagrams:** - **Embryology overview** [Embryonic Development - Embryology (unsw.edu.au)](https://embryology.med.unsw.edu.au/embryology/index.php?title=Embryonic_Development) **Videos:** - **Development of the Face**: ​ https://www.youtube.com/watch?v=FhhWG3XzARY​ - **Oral Tissue Development -- bud, cap, bell** - **Bud and Cap stage of Tooth Development:** - **Bell Stage: Embryology of the Crown**  ​ - Amelogenesis in detail - **Overview of Embryology of the Root** ​ - **Embryology of the root in detail** [[v=dEHv4BYfbBY&t=1s]](https://www.youtube.com/watch?v=dEHv4BYfbBY&t=1s) **Core articles:** - **Overview of oral embryology:** Magreni, A. and May, J. G. (2015) Embryology of the oral structures, *Operative Techniques in Otolaryngology-Head and Neck Surgery, *26 (3), pp. 110-114. DOI: [[https://doi.org/10.1016/j.otot.2015.06.002]](https://doi.org/10.1016/j.otot.2015.06.002). - **Overview of tooth development** Thesleff I. (2014). Current understanding of the process of tooth formation: transfer from the laboratory to the clinic. *Australian dental journal*, *59 Suppl 1*, 48--54. [[https://doi.org/10.1111/adj.12102]](https://doi.org/10.1111/adj.12102)  - **Overview of Enamel development (amelogenesis)** Bartlett JD. Dental enamel development: proteinases and their enamel matrix substrates. ISRN Dent. 2013 Sep 16;2013:684607. doi: 10.1155/2013/684607. PMID: 24159389; PMCID: PMC3789414.​ - **Cleft Lip and Palate:** Vyas T, Gupta P, Kumar S, Gupta R, Gupta T, Singh HP. Cleft of lip and palate: A review. J Family Med Prim Care. 2020 Jun 30;9(6):2621-2625. doi: 10.4103/jfmpc.jfmpc\_472\_20. PMID: 32984097; PMCID: PMC7491837. **Optional articles** - **Eruptive tooth movement** Craddock HL, Youngson CC. Eruptive tooth movement\--the current state of knowledge. Br Dent J. 2004 Oct 9;197(7):385-91. doi: 10.1038/sj.bdj.4811712. PMID: 15475894. - **Critical review on the theories of tooth eruption:** Marks, S.C., Jr. and Schroeder, H.E. (1996), Tooth eruption: Theories and facts. Anat. Rec., 245: 374-393. [https://doi.org/10.1002/(SICI)1097-0185(199606)245:2\3.0.CO;2-M](https://doi.org/10.1002/(SICI)1097-0185(199606)245:2%3c374::AID-AR18%3e3.0.CO;2-M) - **A recent review of eruption theories:** Rabea, A.A., 2018. Recent advances in understanding theories of eruption (evidence based review article). *Future Dental Journal*, *4*(2), pp.189-196. - **Overview of tooth regeneration** Baranova, J., Büchner, D., Götz, W., Schulze, M., & Tobiasch, E. (2020). Tooth Formation: Are the Hardest Tissues of Human Body Hard to Regenerate?. *International journal of molecular sciences*, *21*(11), 4031. **Embryology of the head, face, and oral cavity** 1. What are the 3 key embryonic origins that give rise to all tissues in the body? - **[Ectoderm]** (outermost germ layer) -- derivatives include the nervous system, epidermis and sensory organs. Also includes components such as the pituitary gland adrenal medulla and some parts of the mouth ie. Epithelium of the lips, cheeks, parts of the tongue, dental enamel,(cells that produce enamel are called ameloblasts which arise from oral epithelium during tooth development). - Mesoderm - 2. Define the neural crest cells, where they come from and what tissues derive from these? - 3. Complete the table for each key structure during embryogenesis ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- Structure Brief description Timeline during Embryogenesis Clinical significance (if any) ------------------------------------ ------------------------------------------------------------------------- ------------------------------- -------------------------------- Zygote, Morula and Blastocyst Trilaminar disc Neural tube and neuroectoderm Neural crest cells originate from the neural tube\ -structure that forms early in embryonic development from the ectoderm. Stomodeum and the Branchial Arches Face Palate and secondary palate Tongue Cleft lip and palate ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- 4. Fill in the table from the selections below related to the **branchial arches**: Branchial Arches Innervation Muscles Artery Cartilage or bones ------------------ ------------- --------- -------- -------------------- I II III IV V VI Terms to be placed in the table above: mandible maxilla glossopharyngeal nerve trigeminal nerve ------------------------------ -------------------- ------------------------ ------------------ -- muscles of facial expression aortic arch 1 aortic arch 3 hyoid bone aortic arch 2 Merkel's cartilage Reichert's cartilage hyoid bone muscles of mastication malleus incur **Embryology of the Oral Tissues** 1. Name the **three embryonic origins (tissue layers)** that give rise to all the structures in the human body? Give an example organ for each. - - - 2. **Label the diagram** below using the labels listed -- these are the structures that we will be learning about how they form:  *enamel,* *dentine,* *pulp,* *alveolar bone,* *gingiva,* *periodontal ligament,* *cementum,* *apical foramen,* *apex of the tooth* **\ ** 3. The following diagrams: **7a-7d** reflect the stages of the development of teeth. Name the **stage, label the cells indicated by the arrows and select the purpose**: a. **Stage:** **Label cells:** oral epithelium (OE), ectomesenchyme (E) and basement membrane (BM) **Select the purpose/function of stage:** a. The enamel organ forms from the oral epithelium and the underlying ectomesenchyme forms the dental papilla surrounded by the dental follicle b. The dental lamina starts to form where oral epithelium thickens in a band at the same time as the vestibular lamina c. The enamel organ deepens to determine the shape of the tooth, the cells differentiate ready for odontogenesis to take place d. The oral epithelium of the dental lamina start to proliferate into the underlying ectomesenchyme at specific sites**[\ ]** b.  **Stage:** **Label cells:** oral epithelial cells of the bud (OE), underlying ectomesenchyme (E), basement membrane separating the oral epithelial cells and ectomesenchyme cells (BM), dental lamina (DL) **Select the purpose/function of stage:** a. The enamel organ forms from the oral epithelium and the underlying ectomesenchyme forms the dental papilla surrounded by the dental follicle b. The dental lamina starts to form where oral epithelium thickens in a band at the same time as the vestibular lamina c. The enamel organ deepens to determine the shape of the tooth, the cells differentiate ready for odontogenesis to take place d. The oral epithelium of the dental lamina start to proliferate into the underlying ectomesenchyme at specific sites that represent the future position of each tooth c. **Stage:** **Label cells**: dental follicle (DF), enamel organ (EO), dental papilla (DP), underlying ectomesenchyme (E), basement membrane separating the enamel organ from the dental papilla (BM), oral epithelium (OE) **Select the purpose/function of stage:** a. The enamel organ forms from the oral epithelium and the underlying ectomesenchyme forms the dental papilla surrounded by the dental follicle b. The dental lamina starts to form where oral epithelium thickens in a band at the same time as the vestibular lamina c. The enamel organ deepens to determine the shape of the tooth, the cells differentiate ready for odontogenesis to take place d. The oral epithelium of the dental lamina start to proliferate into the underlying ectomesenchyme at specific sites **[\ ]** d.  **Stage:** **Label cells**: dental sac (DS), dental follicle (DF), stellate reticulum (SR), dental papilla (DP), cervical loop (CL), successional lamina (SL), outer enamel epithelium (OEE), inner enamel epithelium (IEE) **Select the purpose/function of stage:** a. The enamel organ forms from the oral epithelium and the underlying ectomesenchyme forms the dental papilla surrounded by the dental follicle b. The dental lamina starts to form where oral epithelium thickens in a band at the same time as the vestibular lamina c. The enamel organ deepens to determine the shape of the tooth, the cells differentiate ready for odontogenesis to take place d. The oral epithelium of the dental lamina start to proliferate into the underlying ectomesenchyme at specific sites **Embryology of the Crown** 4. Place the cells into the appropriate section of the flow chart representing the differentiation pathway: **Pulpal cells, inner enamel epithelium (IEE), outer enamel epithelium (OEE), ameloblasts, stellate reticulum, stratum intermedium, pre-ameloblasts, pre-odontoblasts and odontoblasts** 5. Label the following diagram in relation to the histological development of teeth: *Dental lamina, dental papilla, dental sac, outer enamel epithelium, cervical loop, ectomesenchymal cells, inner enamel epithelium, stratum intermedium, stellate reticulum, permanent tooth's successional lamina* 6. **Number these stages in order of when they occur during the embryology of the crown** Order Stages ------- -------------------------------------------------------------------------------------- Enamel matrix is laid down Pre-dentine is laid down Dentinogenesis starts at the cusp tips The enamel matrix is mineralized The dentine matrix is mineralized Stellate reticulum cells deflate Stellate reticulum and stratum intermedium cells disappear Pre-ameloblasts are triggered by dentine matrix to differentiate into ameloblasts Pre-odontoblasts are triggered by pre-ameloblasts to differentiate into odontoblasts Amelogenesis starts at the cusp tips The inner enamel epithelial cells differentiate into pre-ameloblasts The outer periphery cells of the dental papilla differentiate into pre-odontoblasts 7. **The lifecycle of the ameloblast is:** a. limited to the time the tooth erupts b. limited to the time crown formation is complete c. limited to the life of the tooth d. limited to the completion of the bell stage 8. **The lifecycle of the odontoblast:** a. is complete by the time the tooth erupts b. is complete by the crown has formed c. continues throughout the life of the tooth d. continues until the pulp formation is complete 9. D**escribe the two stages of amelogenesis.** 10. **The formation of the pulp:** a. Takes place during crown formation and is complete before the tooth erupts b. Takes place after crown formation and is complete after the tooth erupts c. Takes place during crown formation and is complete when the root is fully formed d. Takes place before crown formation and is complete before the tooth erupts 11. Complete the table below: Features Amelogenesis Dentinogenesis ------------------------------------------------ -------------- ---------------- Cell Location it begins Pattern of formation Direction in relation to dental papilla When is it complete? Source of vascular supply Outcome of cell after crown formation complete **\ Embryology of root and supporting structures** 12. **Identify** in the diagram below **the structures associated with the tooth root** -- these are the structures that we will be learning about how they form: 13. Using your knowledge of cells involved in tooth development so far, what cells do you think form the structures identified above: e. Cell: Odontoblasts f. Cell: Cementoblasts g. Cell: Fibroblasts h. Cell: Osteoclasts i. Cell: Ectomesenchyme 14. Label the cells in this diagram indicated by the lines, and the stage below:  **Stage:**... **Label cells:** Dentine (D), Enamel (E), ectomesenchyme of the pulp, epithelial root sheath (HERS), OEE, IEE, dental sac, cervical loop, dental sac, odontoblasts, stratum intermedium, stellate reticulum **Select the single best answer:** 15. Dentinogenesis of the tooth root: a. Continues in a similar process to dentinogensis of the crown b. Is triggered by contact with enamel matrix laid down by the ameloblasts c. Is triggered by contact with cementum matrix laid down by the ameloblasts d. Is complete at the time the tooth erupts 16. Cementogensis is : a. carried out by the cementoblasts that originate from the ectomesenchyme of the dental sac and likely hertwigs epithelial root sheath b. a process whereby cementum matrix is laid down and then mineralized by osteoblasts c. completed when the cementoblasts reach the apical foramen d. is a process that forms the cementum and dentine of the tooth root 17. The periodontal ligament: a. Forms from the collagen fibres that are deposited by cementoblasts b. Creates the attachment of the tooth from the root dentine to the alveolar bone c. Formation is triggered by HERS mapping out the shape of the root d. Formation is carried out by fibroblasts that differentiated from the dental sac 18. Match the following words to the statements: j. Epithlial rests of Malazzez, remnants of HERS that have not disintegrated may be observed in the [ ] may play a role in regeneration and cysts. k. Alveolar bone originates from the ectomesenchyme cells surrounding the [ ]. l. Enamel pearls are a result of a disruption in the processes where residual [ ] near the CEJ differentiate into ameloblast. m. The formation of the root continues after [ ] is complete. e. 19. Make notes on the stages of root formation For example -- make notes about each label, where it differentiated from, what cell forms it, what structure it forms etc A map of the world Description automatically generated with low confidence **[\ ]** **Embryology of eruption and exfoliation** 5. **Label** the cells indicated by the arrow associated with the enamel organ in the advanced bell stage - these cells will play a role in eruption too: *Stellate reticulum, stratum intermedium, ameloblasts, outer enamel epithelium*  6. Using your knowledge of the ameloblast cell lifecycle, the role once **amleogenesis is complete** of the ameloblast is to: a. Mineralise the secreted enamel matrix b. Reduce in size and from a protective layer with the remaining cells of the enamel organ c. Undergo apoptosis along with the disappearing stellate reticulum d. Use its Tome's process to secrete enamel matrix e. Differentiate into cementoblasts to form the root **\ ** 7. **The eruption process of teeth...** a)     Starts during the bell stage of tooth development b)     Starts after birth for all the primary teeth c)     Starts once the root formation of a tooth is complete d)     Starts at the same time as the crown formation begins 8. **The reduced enamel epithelium...** a. Forms a protective layer over the tooth root during eruption b. Forms from ameloblasts during amelogenesis c. Surrounds the developing tooth crown during eruption d. Fuses with the oral epithelium to form the periodontal attachment with the tooth **Section 2b: *Questions post-session:*** 9. **The three phases of eruption include:** a. Primary eruption, permanent eruption and exfoliation b. Pre-eruptive, active eruptive and post-eruptive c. Crown formation, root formation and eruption d. Pre-eruptive, intraosseous and supraosseous 10. **The dento-gingival junction is important:** a. to protect the crown with the reduced enamel epithelium b. to seal the oral cavity off to the internal environment c. to enable eruption of the tooth d. to form the gingival sulcus with the tooth root 11. Drawing on your knowledge obtained during the oral embryology sessions, identify and describe the 4 stages of development happening in this diagram and label as many features as you can: Diagram Description automatically generated 12. Have a good look at the radiographic image below...is there anything that does not look normal in terms of the eruption pattern of the teeth present? Make some notes on your thoughts and we will discuss. **[\ ]** **Glossary of terms** Fill in the table and add to it throughout your learning especially in embryology. It may also be useful for other areas of your learning helping to familiarise with dental terminology. Terminology Definitions Alternative terminology ------------- ------------- -------------------------