Our crown procedure starts with a diagnosis. Standard diagnostic techniques determine the pre-operative state of the tooth and its influence on the outcome. Once a diagnosis has been confirmed, treatment commences with local anesthesia. In the past as the first step we would administer epinephrine with our anesthetic. Now we commence anesthesia with mepivicaine without epinephrine. This traditionally is formulated without epinephrine. We figure the boost in epinephrine you get from the beginning of a dental procedure is enough to create stability and safety. So after slow administration, a digital scan impression of the opposing arch of the tooth of interest is completed. At this time the first dose of anesthesia has taken effect then a low dose of epinephrine with articaine is given for quick and profound anesthesia. This allows us to begin the procedure in less time with less risk of adverse effects due to epinephrine. These effects would be syncope, dizziness, tremors, and increased breathing. We’ve honed this procedure over years and found it gives patients enough comfort to start the procedure and enough “readiness” for safety.
We start with a crown down procedure which removes a large part of the outside covering of the tooth. This covering is enamel and dentin. Utilizing a bite block or prop to stabilize or prevent movement, retraction cord is carefully packed into the crevice located immediately surrounding the tooth or teeth of interest. After the cord is in place, refinement of the tooth preparation occurs at this point. Retracting the components surrounding the tooth allows for refinement in relation to the gingiva (gums), bone, tooth ligament, and neighboring teeth. This is important for what we call “emergence profile”. Creating a tooth crown that mimics a natural tooth emerging from the underlying bone and gums. This is important for long-term health. In our population of people this generally takes us within a millimeter of the top of the gums to one millimeter below it. If saving a tooth is necessary in achieving arch stability, the preparation craters to root anatomy and crevices, occlusal discontinuities and periodontal partitions which all influence long term stability.
Just as a reminder, we are crowning the tooth in order to reduce the chance of individual and multiple tooth failure. If this happens you will decrease the expense and morbidity associated with your dental problems. Crowning a tooth lessens the chance of one or more of your teeth suffering the effects of primary, secondary and tertiary dental problems. That is, tooth decay, periodontal disease, painful, dying teeth, and chewing dysfunction are all reduced. Space maintenance with crowns result in more stability long-term and mitigates the effects of tooth loss by reducing the cost of treatment over time.
So after refinement occurs this sets up the next step. The next step includes a product named GLUMA. This product is common in the field of dentistry and is used to reduce dental sensitivity and also kills bacteria to which the tooth is exposed during the procedure. Three coats of GLUMA are applied and lightly dried. If any blood is present from the gingiva it is controlled with epinephrine-infused cotton pellets. The epinephrine helps control bleeding from inflammed and traumatized gums.
Once a dry field is achieved, using our Cerec scanner, we scan the tooth. For the design and manufacturing of the crown it generally takes 40 minutes. This usually serves as some down time for a patient. GLUMA helps with any sensitivity due to the anesthesia wearing off prior to cementation.
Once the crown is ready, a patient is prepared for the crown-fitting and cementation procedure. When fitting we check for marginal adaption of the crown to tooth and contacts to the neighboring teeth. We polish the neighboring teeth and isolate the tooth to prepare for cementation. We use Relyx self-adhesive resin cement. Prior to the cement we blot the tooth dry with care not to desiccate the tooth completely. Cement is loaded into the crown and crown seated. The cement sets with a blue light used to set dental materials. We use a dental scaler and floss to clean off the cement. At this time your gums may be slightly tender to manipulation since the anesthesia will be wearing off by that time. Once cement has been removed, the occlusion on the crown is checked with articulating or biting paper. Adjustments are made at this time followed by a polisher on all surfaces in aid to remove all cement and smooth any irregular areas.
We take radiographs after most crown procedures for two purposes- to assure complete cement removal around the gums and to inspect the fit of the crown margins. This is the last step.
Our crown procedure has yielded a less than 7% 5 year failure rate. Of the teeth crowned in our office over five years, 3% have been either removed or required root canal therapy. Failures are usually associated with the pre-operative status of the tooth and teeth around it. A small percentage of crown failure cases are due to cement failure and/or crown fracture.