When was the last time you thought about the models in your office? If you use a system such as CEREC the number of models you have may be somewhat reduced. However, chances are you still have the need for stone models in your practice.

While it's easy to fabricate quality stone models, it's also easy to turn what could be excellent models into significant sources of error. The following are three simple steps that will improve the consistency and quality of your models.

  1. All stones and plasters are designed to work with a specific water to powder ratio. If this ratio is altered the properties of the stone or plaster will be impacted. Think of it like baking a cake; if you just guess on the amounts of your ingredients you are very likely to end up with a poor result. There are wonderful devices such as the Aquaspence from Whip Mix that will measure the amount of powder you have and add the appropriate amount of liquid. These devices are costly and are suited for laboratories and large offices. For smaller offices the cost-effective solution is to measure your water using a graduated cylinder and weigh the stone using a postage or digital scale for jewels. Another simple option for stone and plaster is to buy pre-measured packets.
  2. The next important step is to use the appropriate stone or plaster for the job at hand. While something like Stat Stone can work great for things like bleaching trays or quick fabrication of anterior deprogrammers, it's not the best choice for diagnostic models or crown and bridge models. The bottom line here is pick a stone or plaster that is indicated for your planned use.
  3. Last but certainly not least is vacuum mixing. With most materials vacuum mixing results in greatly improved quality. The downside to this technique is that if you don't have a vacuum mixer you are going to have to invest significantly more than you did to measure your powder and liquid. If you desire to limit your investment you could purchase a used unit; many dentists have units that are decades old and still going strong. However, if your budget allows for a newer unit, they are programmable for different materials, quiet, have little to no vibration and even hold the mixing bowl in place automatically. Either way, with a new or old unit I encourage you to make the investment in a vacuum mixer.

John R. Carson, DDS, PC, Spear Visiting Faculty. [ www.johnrcarsondds.com ]