Silicone bite registration material has become a standard in today’s practice. So much so, that we consider the use of wax very old school. With the advent of this new material, came some new challenges. Silicone and saliva do not mix. It can be difficult for us and uncomfortable for the patient when the material is sliding off the teeth and down the throat as it is being injected. Another challenge is keeping the patient from wiping the material off of the teeth with their tongue, or pushing it tot he buccal. I have learned some very simple tips that make using silicone bite registration material quick, efficient and very predictable.
First make sure that the teeth have been adequately dried before injecting this material. If the teeth are moist with saliva the silicone will run off the teeth and often slides right into the back of the mouth. In our office we do this either by blowing air with the air water syringe tip, or by having the patient bite on a tissue that has been folded and placed in a miller forcep.
Second, always apply the silicone against the maxillary teeth and then have the patient close. If you try and inject the material against the mandibular teeth, the patients tongue will wipe the material away from the lingual and often ruins the record. Lastly, make sure you inject enough material to capture several millimeters beyond the buccal and lingual tooth surfaces. A thick rope of material should be used as in the photo with this post. This will capture the cusp tips on both sides of the tooth, allowing the record to be trimmed once set without breaking into fragments.
Remember, silicone records are more accurate then stone casts. For this reason, they need to be accurately trimmed to remove all the occlusal and interproximal anatomy that they capture. Failure to trim the record either by you or your technician will result in the model not seating completely during mounting, and your restorations coming back high.