Q: What is Borax?
- .Retarder
- .Accelerator
- .None of the above
Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate. It can be used as a fertilizer, chalk, or stone for the fabrication of models in dentistry. Borax and potassium sulfate can be added to the gypsum to modify the speed at which the material sets (hardens).
- Borax is a retarder
- Potassium sulfate is an accelerator
Borax is also used as a retarder in other materials such as concrete.
Tips: BORed rhymes with BORax. When things are slow, don’t you get bored? I hope this makes sense!
Answer: (A). Retarder
While we are at it, let’s learn a little more about gypsum. It is the most commonly used material for replication in dentistry. Here are different types of gypsum, from low to high strength:
- Plaster (type II): irregular porous particles. High setting expansion and low compressive strength. Requires more water.
- Stone (type III): less irregular particles. Low setting expansion and higher compressive strength. Used for study models.
- Diestone (type IV and V): non-porous, smoothest, and dense particles. Highest compressive strength. Used for the replication of crowns and bridges.
One more thing to know about gypsum is that it produces heat (exothermic reaction) from the chemical reaction of hemihydrate and water.
Hope your day became a little more fulfilling knowing that you learned something for the dental assisting board exams (RHS®, ICE®, GC and more) with SmarterDA. Next time you are in the lab fabricating a replica, try to recall this knowledge. It takes at least 3 times to remember a new information according to science, so make sure you keep looking at the same info again and again. This way, you will be more ready for the dental assisting board exams!
SmarterDA wishes you #SuccessAndNothingLess!
Author: Claire RDH, CDA, MS
Claire is the founder of StudentRDH and SmarterDA – exams prep solutions for the dental hygiene and dental assisting students. The exam review online solutions quickly became the #1 choice among students. “Studying is now “addictive!”
Prior to her career in the dental field, Claire Jeong was an education specialist at Boston Children’s Museum. Claire is licensed to practice in the United States and Canada. She can be reached at ClaireJ@SmarterDA.com and support@SmarterDA.com.