Orthodontics | PRACTICE QUESTIONS | INBDE, ADAT
TLDRIn this comprehensive orthodontics series finale, Ryan reviews 15 practice questions that test knowledge on various orthodontic topics. The video covers a range of subjects, including craniofacial growth and development, clinical presentations in children, the effects of trisomy 21, force vectors in orthodontic treatment, occlusion classifications, serial extraction protocols, synchondrosis closure, molar relationships, orthodontic wire materials, and specific orthodontic conditions. Two case-based questions explore treatment options for a child with a minor midline diastema and another with a unilateral posterior crossbite. The video emphasizes the importance of understanding orthodontic principles and applying conservative treatment approaches when appropriate.
Takeaways
- 🦷 The cranial vault is formed by intramembranous ossification, while the cranial base is primarily endochondral, with some intramembranous growth.
- 👶 In primary dentition, it's common for children to present with minimal overbite or a slight open bite due to habits like thumb sucking.
- 🧬 A patient with trisomy 21 (Down syndrome) typically presents with maxillary hypoplasia, upslanting eyes, and relative macroglossia, but not necessarily high caries risk.
- 🔴 Class 3 elastics apply a mesial and extrusive force to the maxillary first molars, affecting the direction of their movement.
- 🦴 Class II occlusion is indicated when the mesial buccal cusp of the maxillary first molar is mesial to the buccal groove of the mandibular first molar.
- 🦷 Serial extraction typically follows the order of primary canines, primary first molars, and permanent first premolars (CD4).
- 🕰️ The sphenocipital synchondrosis closes last among the cranial base synchondroses, which is a significant factor in facial growth.
- 📉 A distal step in primary dentition is a strong predictor for the development of a Class II molar relationship in permanent dentition.
- 🚫 For patients with a nickel allergy, beta titanium is the preferred orthodontic wire material as it does not contain nickel.
- 🤔 Conditions like Pierre Robin sequence and Treacher Collins syndrome present with mandibular retrognathia and cleft palate, but the former involves glossoptosis.
- ⬆️ Orthognathic surgery stability is ranked from moving the maxilla up as the most stable to setting the mandible back as the least stable.
- 📊 Moyer's space analysis is used to predict the mesio-distal width of permanent canines and premolars using a prediction table and the sum of the widths of the lower incisors.
Q & A
What is the primary method of ossification for the cranial vault?
-The cranial vault is formed by intramembranous ossification at the fontanelles and the sutures, as well as the internal and external surfaces.
How is the cranial base formed in terms of ossification?
-The cranial base, consisting of the ethmoid, sphenoid, and occipital bones, initially forms in cartilage and then ossifies into bones, leaving behind synchondrosis between those bones. Endochondral ossification occurs at these synchondroses through childhood and adulthood.
What type of ossification does the maxilla undergo?
-The maxilla undergoes intramembranous ossification at the sutures posterior and superior to it and also to remodel the surfaces. There is no cartilage in the maxilla, so it does not undergo endochondral ossification.
How does the mandible grow in terms of ossification?
-The mandible grows by both intramembranous and endochondral ossification. Intramembranous ossification is used to create the corpus or the body and the ramus, while endochondral ossification is used to create the condylar cartilage.
What is the typical clinical presentation of a child in primary dentition?
-Most young children, especially before the age of three, present with minimal overbite or slight open bite in the primary dentition due to habits like thumb sucking or using a pacifier.
What is the typical feature associated with a patient with trisomy 21?
-Patients with trisomy 21, also known as Down syndrome, typically present with maxillary hypoplasia, upslanted eyes, and relative macroglossia. High caries risk is not correlated with this syndrome.
In what direction does the maxillary first molar move when class three elastics are used?
-When class three elastics are used, the maxillary first molars experience movement in a mesial and extrusive direction.
What occlusion is present when the mesial buccal cusp of the permanent maxillary first molar is mesial to the buccal groove of the permanent mandibular first molar?
-When the mesial buccal cusp of the permanent maxillary first molar is mesial to the buccal groove of the permanent mandibular first molar, it indicates a class II molar relationship.
What is the typical order of removing teeth if serial extraction is chosen as the treatment for severe crowding?
-The typical order for serial extraction is primary canines, primary first molars, and then permanent first premolars, which can be remembered by the mnemonic 'C, D, 4'.
Which synchondrosis closes last in the cranial base?
-The sphenocipital synchondrosis closes last, which can be as late as around age 18.
What molar relationship is most likely to develop in the permanent dentition from a distal step in the primary dentition?
-A distal step in the primary dentition is almost 100% likely to result in some level of class II molar relationship in the permanent dentition.
Which orthodontic wire material would be the best choice for a patient with a nickel allergy?
-Beta titanium, also known as TMA (titanium, molybdenum, molybdenum alloy), would be the best choice as it does not contain nickel.
Which condition presents with glossoptosis, mandibular retrognathia, and cleft palate?
-Pierre Robin sequence presents with these conditions, characterized by a small mandible leading to backward displacement of the tongue (glossoptosis), which interferes with palatal development, often leading to cleft palate.
How should orthognathic surgery procedures be ordered from lowest to highest chance of post-surgical relapse?
-The order from lowest to highest chance of post-surgical relapse is: maxilla up, maxilla forward, and mandible back.
Which space analysis predicts the mesio-distal width of permanent canines and premolars using a prediction table and a sum of the widths of the lower incisors?
-Moyer's space analysis involves adding the width of the mandibular incisors, referring to a prediction table, and is the method that matches the criteria.
What is the recommended treatment for a 10-year-old child with an unesthetic space of just under two millimeters between their two front teeth?
-The recommended treatment is to wait for the upper canines to erupt, as mesial eruption should close a space less than two millimeters, which is considered a normal stage of dental development.
What is the preferred treatment for an 8-year-old child with a unilateral posterior crossbite and a functional shift to the right?
-The preferred treatment is the use of a hyrax expander to relieve the posterior crossbite and prevent future developmental issues.
Outlines
😀 Orthodontics Series Recap and Practice Questions
Ryan introduces the final video in the orthodontics series, which focuses on reviewing 15 practice questions that cover the material from the series. He advises viewers to watch the full series before attempting the questions. The video includes a breakdown of ossification types in craniofacial bones, clinical presentations in children's primary dentition, and characteristics of patients with trisomy 21. Each question is followed by a pause for viewers to consider their answers.
🦷 Understanding Occlusion and Orthodontic Elastics
The video delves into the force vectors involved with class three elastics in orthodontics, explaining how they affect the maxillary first molars. It also discusses the Angle classification system for permanent molars, identifying class one occlusion and its characteristics. The video provides a visual guide to the different types of occlusion and the expected outcomes from orthodontic treatments.
🧠 Serial Extraction and Cranial Base Synchondroses
Ryan discusses the concept of serial extraction, providing a mnemonic to remember the order of tooth extraction. He also explains the timing and closure of various synchondroses in the cranial base, emphasizing the sphenocipital synchondrosis as the last to close. The video offers a visual representation of the cranial base synchondroses for better understanding.
🦷 Predicting Molar Relationships in Dentition
The video addresses the concept of distal step in primary molars and its implication for molar relationships in permanent dentition. It highlights the near certainty of a class 2 molar relationship following a distal step in primary dentition. The explanation aids in understanding the progression and potential outcomes in orthodontic cases.
🤝 Choosing Orthodontic Wires and Understanding Syndromes
Ryan talks about selecting orthodontic wire materials for patients with nickel allergies, recommending beta titanium as a suitable option. He also covers various syndromes, including the characteristics of Pierre Robin sequence, Treacher Collins syndrome, and fetal alcohol syndrome. The video provides insights into the clinical features and implications of these conditions in orthodontics.
🔄 Stability Hierarchy in Orthognathic Surgery
The video outlines the stability hierarchy in orthognathic surgery, explaining the stability and predictability of different surgical procedures. It details the impact of moving the maxilla and mandible in various directions and the chances of post-surgical relapse. The information is crucial for planning and executing orthognathic surgeries.
📏 Space Analysis and Tooth Movement Dynamics
Ryan discusses space analysis methods that predict the mesio-distal width of permanent canines and premolars, highlighting the Moyer's space analysis as the most suitable. The video also explains the sequence of events that occur when a heavy orthodontic force is applied to teeth, covering pressure-induced changes in the periodontal ligament and tooth movement over time.
🦷 Treatment Options for Diastema and Crossbite in Children
The video presents case-based questions involving a 10-year-old child with a diastema and an 8-year-old with a unilateral posterior crossbite. Ryan recommends conservative approaches, such as waiting for natural mesial eruption to close minor spaces and using a hyrax expander for posterior crossbites. He emphasizes the importance of early intervention in certain orthodontic cases.
📚 Final Thoughts and Channel Support
Ryan concludes the orthodontics series by inviting viewers to like the video, subscribe to the channel, and support the content through Patreon. He mentions the benefits of becoming a patron, such as accessing video slides and board exam practice questions, and expresses gratitude for the viewers' engagement in the series.
Mindmap
Keywords
💡Intramembranous Ossification
💡Endochondral Ossification
💡Primary Dentition
💡Trisomy 21
💡Class II Molar Relationship
💡Serial Extraction
💡Synchondrosis
💡Posterior Crossbite
💡Orthodontic Wire Materials
💡Pierre Robin Sequence
Highlights
Final video in the orthodontics series covering 15 practice questions to test knowledge.
Recommendation to watch the full series before attempting practice questions.
The cranial vault is formed by intramembranous ossification, not endochondral.
Cranial base ossifies from cartilage into bones with synchondrosis, followed by endochondral ossification.
Maxilla undergoes intramembranous ossification at sutures and surfaces.
Mandible grows by both intramembranous and endochondral ossification.
Children in primary dentition often present with minimal overbite or slight open bite due to common habits like thumb sucking.
Trisomy 21 (Down syndrome) is associated with maxillary hypoplasia, upslanting of the eyes, and relative macroglossia.
Class III elastics apply a mesial and extrusive force to the maxillary first molars.
Angle classification system: Class I occlusion has the maxillary first molar's mesial buccal cusp occluding with the mandibular first molar's buccal groove.
Serial extraction typically follows the order of primary canines, primary first molars, and permanent first premolars (CD4).
The sphenocipital synchondrosis is the last to close, around age 18.
Distal step in primary dentition is a strong predictor for some level of Class II in permanent dentition.
Beta titanium is the best orthodontic wire choice for patients with nickel allergies as it does not contain nickel.
Pierre Robin sequence involves a small mandible leading to glossoptosis, which can interfere with palate development leading to cleft palate.
Orthognathic surgery stability hierarchy: Maxilla up is most stable, followed by Maxilla forward, and Mandible back is least stable.
Moyer's space analysis predicts the mesio-distal width of permanent canines and premolars using a prediction table and the sum of the widths of the lower incisors.
When a heavy orthodontic force is applied, the periodontal ligament (PDL) compresses on the pressure side and stretches on the tension side, followed by hyalinization and undermining resorption before tooth movement.
For a 10-year-old child with an unesthetic space between the front teeth, waiting for upper canines to erupt is the recommended treatment if the diastema is less than two millimeters.
An expander is the preferred treatment for an 8-year-old child with a unilateral posterior crossbite and functional shift to correct early and prevent future development issues.
Transcripts
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