All-ceramic and adhesively retained restorations offer the possibility of limited to no removal of tooth structure. Because the restoration is adhesively retained, less structure needs to be removed to accomplish the restoration. Therefore, we can reduce the risk of tooth fracture by covering the cusps and bonding the restoration, all the while not compromising the prognosis of the tooth. Chairside CAD/CAM offers the possibility to provide this treatment in the same visit. The Planmeca FIT restoration system combines PlanScan, PlanCAD, and PlanMill 40 to offer this same-visit solution.
It is important to remove as little of the original tooth as possible when creating restorations because of the biological consequences involved with the loss of the structure. There is more risk associated with a tooth that is lost to decay or fracture, or when the tooth is removed to restore the tooth to its natural contour and function.
How can we do this effectively and efficiently in practice?
A tooth that has a restoration exceeding just 1/3 of the occlusal isthmus width is at an increased risk for cuspal fracture. Once a cusp fractures, the overall strength of the tooth has been compromised and further fracture or loss of the tooth is possible, even if a crown or partial crown has been placed.
A proactive approach would benefit the patient and reduce the risk of future quality of life issues. When a tooth has a restoration that exceeds 1/3 of the intercuspal width, it is critical to cover the cusps of the tooth to reduce the risk of fracture. Concurrently, one should take care to remove as little of the tooth structure as possible to not increase the risk by removing more than what is needed to restore the tooth.
Traditionally, this was treated with an onlay or full coverage gold restoration fabricated by a laboratory requiring multiple visits. When porcelain fused to metal crowns became a viable option, patients began to elect this option because it was more esthetically pleasing. In order to camouflage the metal, the margin of the preparation was hidden under the gingival tissue. This required more removal of tooth structure. While the PFM is still appropriate in some cases, we now have the ability to provide an esthetic option that doesn’t require as much removal of the tooth.
The Planmeca FIT open CAD/CAM system is the chairside solution to better dentistry for healthier teeth. Digital impressions of the tooth preparation, opposing teeth, and maximum intercuspation of the teeth are taken using the PlanScan scanner. Planmeca PlanCAD software is used to design the restoration and the restoration is milled with the PlanMill40 using an IPS e.max CAD monolithic porcelain block. This specific block offers excellent esthetics which can be further stained and customized to optimize the appeal. After crystallization, the restoration is properly cleaned and the tooth is prepared for bonding. The restoration is placed using an adhesive resin cement.
Survival analysis studies have shown that single lithium-disilicate full coverage crowns, and inlay and onlay restorations, have been shown to have very good survival rates compared to PFM and gold restorations. Same-day visit CAD/CAM fabricated restorations have proven to be a viable choice with excellent longevity. Furthermore, it has been shown that a digital impression is the preferred method for patients in lieu of the traditional impression. The digital impression technique has also been shown to be faster, resulting in improved workflow efficiency. Same-visit restorations eliminate the challenge of placing and retaining a provisional restoration for a partial coverage or minimally invasive crown preparation. In conclusion, the Planmeca FIT open CAD/CAM system provides an effective, efficient, and patient-preferred method to restore a tooth at risk, while not increasing the risk to the tooth.
About the Author: Michael L. Young, DDS, is in private practice in Sterling Heights, Mich.. He has employed chairside CAD/CAM dentistry since 2004 and has placed almost 2,000 restorations using this technology. He is a Mentor for the Kois Center for Advanced Dental Learning, and the Founder and CEO of Digital Dentistry Solutions, Inc.