Dentosphere : World of Dentistry

# Molar relation in primary dentition is determined by: A. Mesiobuccal cusp of maxillary first molar B. Buccal groove of mandibular first molar C. Distal surface of maxillary and mandibular second molar D. Distal surface of maxillary and mandibular first molar Share

When you stand in the toothpaste aisle, the options can feel overwhelming. Natural, organic, non-fluoridated toothpastes promise a “clean” smile without chemicals—but are they really the best choice? Fluoridated toothpaste, backed by decades of science, remains the gold standard for cavity protection and overall oral health. So, what’s the real difference between fluoridated and non-fluoridated toothpaste, and why should you stick with fluoride? Let’s break it down. What Is Fluoride, and Why Does It Matter? Fluoride is a naturally occurring mineral found in water, soil, and even some foods. In toothpaste, it’s a superhero for your teeth. It strengthens enamel—the hard outer layer of your teeth—making it more resistant to acid attacks from sugary snacks or bacteria. Non-fluoridated toothpastes skip this ingredient, often replacing it with alternatives like charcoal, baking soda, or herbal extracts. While these sound appealing, they lack fluoride’s proven ability to fight cavities. The A...

Question 1. According to Wolff’s law: A. Human teeth drift mesially as interproximal wear occurs B. Pressure causes bone resorption C. The optimal level of force for moving teeth is 10 to 200 gm D. Bone trabeculae line up in response to mechanical stress Correct Answer: D Question 2. Overjet is defined as: A. Horizontal overlap B. Vertical overlap C. Transverse plane discrepancy D. All of the above Correct Answer: A

 1. Which biomechanical principle explains the differential force theory in orthodontic tooth movement? a) Hooke’s Law b) Newton’s Third Law c) Wolff’s Law d) Poiseuille’s Law e) Archimedes’ Principle The correct answer is: (a) Hooke’s Law Explanation: The Differential Force Theory in orthodontic tooth movement states that different types of teeth require different magnitudes of force to move efficiently while minimizing unwanted side effects. This concept is based on Hooke’s Law, which states that the force applied to a material is proportional to the deformation it experiences, as long as the elastic limit is not exceeded (F = kx). In orthodontics: Applying lighter forces to teeth with single roots (e.g., incisors) ensures controlled movement. Higher forces are required for multi-rooted teeth (e.g., molars) due to their increased root surface area and resistance. Thus, Hooke’s Law plays a crucial role in explaining how force magnitude should be adjusted based on the tooth’s bio...

 # The first evidence of cartilage getting converted to bone in craniofacial skeleton occur during: A. Fourth postnatal week B. Eighth prenatal week C. Fourth prenatal week D. Eighth postnatal week The first evidence of cartilage converting to bone (endochondral ossification) in the craniofacial skeleton occurs during the eighth prenatal week. This timing aligns with the development of the cranial base (e.g., occipital, sphenoid, and ethmoid bones), which undergoes endochondral ossification. While mesenchymal condensations and cartilage models form earlier, the actual replacement of cartilage by bone begins around this period, marking the start of ossification in these regions. Answer: B. Eighth prenatal week