In today’s digital world of restorative dentistry, chairside scanning and milling utilizing CAD/CAM technologies offer a one-visit option for multisurface, single-tooth reconstructive situations. While this solution may seem very desirable both for the dentist’s chair time and for patients’ convenience, the expense for the dentist to invest in the technology can often exceed those benefits. Yet, a convenient one-visit option, without a significant initial financial outlay, would be a very desirable service that dentists could provide for their patients.
A Direct Restorative Alternative
The One Visit Crown (OVC) (Rhondium Corporation) is a direct restorative option for many of the same clinical situations in which one would traditionally choose an indirect onlay or crown. Some of these indications include (1) large amalgam replacements; (2) old and defective MOD restorations of any kind, where the tooth has weakened cusps that need to be protected from the negative effects of occlusal wear and stress; (3) restoration of posterior teeth that have had root canal therapy; (4) cracked teeth; (5) teeth that have severe abfraction on occlusal and facial surfaces; and (6) an economic and conservative alternative to traditional lab-fabricated crowns and onlays. The OVC, originally introduced as a hybrid ceramic that is 73% zirconia filled, is now available in lithium disilicate as well. It can be used to restore molars and premolars in both maxillary and mandibular arches. OVC is composed of a preformed hard anatomic occlusal layer and an uncured sublayer composed of a high-quality posterior composite that allows for adaptation to the prepared tooth.
Selection instruments (Selector Keys) are utilized to determine the correct mesio-distal width of the tooth to be restored so the correct size of OVC can be chosen. The minimal amount of occlusal clearance in the central fossa, cuspal areas, and marginal ridges is 1.5 mm (similar to that required for a lab-fabricated ceramic restoration). Once the preparation is completed, the OVC replica (blue) is used to verify that these space requirements have been met. An OVC matrix band is then placed around the prepared tooth. These innovative bands are formed with 50-μm stainless steel, but are only 10 μm in thickness in the interproximal areas to ensure tight proximal contacts. A conventional Tofflemire retainer can be used with these bands to hold them in place. Next, a standard direct composite bonding technique (etch and bond) is used on all prepared surfaces of the tooth.
The clinician creates the contact points prior to placement of the OVC, if needed. Apply a generous amount of flowable composite (G-ænial Universal Flow [GC America]) on the tooth preparation to prevent bubble formation, and then place the OVC directly onto prepped tooth. Have the patient bite down to confirm seating and vertical position, and then spot-cure, trim excess, and fully cure. To complete the restoration, remove the matrix band, then trim and polish the restoration as required. The entire procedure for an OVC can be finished in about 30 minutes, depending upon the level of experience of the operator.
OVC Case Examples
Figures 1 to 4 show before and after photos of 2 different cases using OVCs to restore teeth that would have otherwise been treated using chairside (CAD/CAM) or lab-fabricated ceramic materials. The buildup of conventionally placed composite resin, together with the occlusal third of the clinical crown (onlay portion) restored using an OVC, creates a hybrid restoration using only direct materials. This treatment protocol can serve as a convenient way to restore badly decimated teeth in certain clinical situations where a less costly and more convenient alternative is desired.
Fiber reinforcement has been used for various clinical situations to help strengthen dental resin materials to better withstand occlusal forces. These fiber networks help transfer the stresses of occlusal load from the weaker resin to the stronger fiber material, helping to prevent failure by fracture. Most fiber reinforcement materials currently on the market are made of polyethylene, which can limit their handling properties and make them more difficult to use. Because their mechanical properties are widely variable, these materials cannot give consistent results when used in clinical situations.
The everStick Crown and Bridge (C&B) (GC America) is a unique fiber reinforcement material consisting of fiber reinforcement embedded in a matrix of polymethyl methacrylate and bisphenol A-glycidyl methacrylate (interpenetrating polymer network) making the fibers bondable to direct dental materials.
For this clinical case, the OVC and everStick C&B were used to create a posterior direct composite bridge and pontic in one visit. For many clinicians, replacement of a missing tooth usually involves a lab-fabricated fixed bridge or an implant-retained restoration, and these options can be very costly. When a patient cannot afford traditional fixed prosthetics, the lower cost option has traditionally been a removable appliance. However, these types of solutions for replacement of single teeth are usually not the first choice for either the patient or the doctor. Utilizing fiber reinforcement products such as everStick gives the patient a good long-term and more economical option that is also easily repaired, if needed.
To test the limits of the OVC, a similar technique was done on a patient requiring a bridge.
A 14-year-old patient was referred by his orthodontist for tooth replacement of congenitally missing maxillary second premolars (Figures 5 and 6). The long-term treatment goal was to hold the space for a future implant by using a fixed appliance that would also restore function and aesthetics during the time of transition.
|Figure 1. A badly decimated mandibular molar (tooth No. 30) is shown prior to the placement of a composite and a One Visit Crown (OVC [Rhondium Corporation]).||Figure 2. A completed view of the OVC restoration completed on tooth No. 30. (Dentistry by Adam Doudney, BDS, PGDipBus; Smile Studio Orewa, Aukland, New Zealand.)|
|Figure 3. Tooth No. 4 had a previous MOD amalgam with internal fractures that necessitated full-coverage protection. The tooth is shown after the completed preparation for an OVC crown.||Figure 4. An occlusal facial view of the completed OVC restoration on tooth No. 4. (Dentistry by Christopher V. Shamlian, DDS; Fresno, Calif.)|
|Figure 5. A preoperative maxillary arch occlusal view showing bilateral congenitally missing teeth in second premolar spaces.||Figure 6. A facial view showing the edentulous space in the No. 5 area.|
|Figure 7. Conservative Class II preparations were done in the abutment teeth for placement of the fiber reinforcement.||Figure 8. The preparations were selectively etched with 37% phosphoric acid for 15 seconds.|
|Figure 9. Using the VITA shade guide, shade A2 was selected for the pontic.||Figure 10. An occlusal view of the fibers (everStick Crown & Bridge [GC America]) after placement and light curing. Note placement of the second fiber to the distal of the first premolar to help guard against lateral forces. Make sure there is adequate space (occlusally to the fibers) to cover with an additional increment of composite.|
Fiber-reinforced direct composite bridges can be a useful alternative to a removable appliance for transitional restoration until a patient is old enough to have an implant placed or a conventional lab-fabricated fixed bridge. No restorative choice is without biologic risk. In cases like this, a traditional acrylic partial (flipper), when used as a long-term transitional appliance, can cause atrophy of the soft and hard tissues in the edentulous space due to the constant occlusal forces during function. This, in turn, would then necessitate extensive grafting procedures later in life to place an implant into the proper position.
A Maryland-type fixed bridge will incur lab expenses and additional chair time that may not may make this alternative a possibility. If this choice is made, replacement and repair during the life of the restoration can be more expensive and time consuming. A fiber-reinforced direct composite bridge, depending upon where it is placed in the dentition, may involve some minimal preparation of tooth structure (as with Maryland-type designs) to allow adequate space for occlusion. However, they will incur no lab charge and can be easily maintained and repaired throughout the life of the restoration.
After the administration of a local anesthetic, conservative Class II cavity preparations (DO in tooth No. 13; MO in tooth J) were done in the abutment teeth (Figure 7). A posterior fiber-reinforced bridge will require a minimum of 2 fibers, spanning the edentulous space, to be embedded in composite resin of the abutment teeth. The first will span the space extending from the disto-occlusal portion of the preparation in the anterior abutment to the distal extent of the preparation in the posterior abutment. This fiber will reinforce the bridge against occlusal forces. The second fiber, placed over the first fiber, extends from the occlusal portion of the posterior abutment extending to the distal of the anterior abutment, then wraps around onto the facial surface of the anterior abutment. (The facial extension will subsequently be covered by direct composite application as described in the steps below.) This second fiber serves to support the bridge against lateral forces during function.
|Figure 11. A sectional matrix (Triodent V3 [Ultradent Products]) was cut and used to create a smooth ovate form on the underside of the pontic, creating a nice contour to the tissue.||Figure 12. Facial view of the pontic after the body was completed with nanohybrid composite (G-ænial Sculpt [GC America]). Note the occlusal clearance made for placement of the OVC to complete the occlusal portion of the pontic.|
|Figure 13. The blue spacer (a replica of the OVC chosen) was used to verify that there was proper occlusal room for placement of the selected OVC.||Figure 14. The OVCs, as packaged, to be used for the construction of the one visit bridge (OVB) are shown. Also shown is a Selector Key used to determine the correct mesio-distal width of the tooth to be restored to choose the correct sized OVC.|
|Figure 15. The OVC was positioned in place, bonding steps completed, then light-cured.||Figure 16. A Uveneer template (Ultradent Products) was used to add composite to the facial aspect of the pontic to bring it in line with the facial surfaces of the abutment teeth.|
|Figure 17. A facial view after removal of the Uveneer template.||Figure 18. A.S.A.P. (CLINICIAN’S CHOICE Dental Products) polishing disc was used for the final polish.|
|Figure 19. Occlusal view; completed OVB restoration.||Figure 20. Facial view; completed OVB restoration.|
|Figure 21. Facial view; completed OVB restoration on the contralateral side.|
After selective-etching the enamel of the Class II preparations with 37% phosphoric acid for 15 seconds (Figure 8), rinsing with water, and then drying, a self-etching bonding agent (G-Premio Bond [GC America]) was applied to the preparation surfaces, air-thinned, and light-cured (per the manufacturer’s instructions). Figure 9 shows an A2 VITA shade guide placed in the edentulous space to compare to adjacent teeth and select the composite and OVC shade choice. After placement of heavy-bodied flowable resin (G-ænial Universal Flow) into the floors of the cavity preparations, the first measured piece of everStick C&B was placed into the uncured flowable resin, pushed into the preparations with a plastic instrument, then light-cured for 20 seconds. The second fiber was then luted into place in the same manner. Figure 10 shows an occlusal view of the 2 fibers luted into place. Next, a small piece of sectional matrix (Triodent V3 [Ultradent Products]) was used as a gingival matrix as the pontic portion of the bridge was built. Again, the heavy-bodied flowable was used to create the bottom of the pontic, which, after light-curing against the matrix, created a smooth convex surface to the composite that touched the edentulous ridge (Figure 11). Next, a nanohybrid composite (G-ænial Sculpt [GC America]) was used to create the body of the pontic on both the facial and palatal sides of the fiber reinforcement (Figure 12). After curing, the OVC blue replica was placed to check the occlusal clearance for the placement of the occlusal one third of the pontic (the OVC). If the body of the pontic were overbuilt occlusally, it could be reduced using a rough diamond bur until the replica verifies that there is adequate space for the placement of the OVC (Figures 13 and 14). Once the separator and OVC were placed, the occlusion and position of the OVC were finalized and then spot-cured so excess could be removed. Once final curing was completed (Figure 15), the OVC was bonded to the remaining portion of the pontic, completing the One Visit Bridge (OVB). After removal of the handle on the OVC, it was determined that the facial contour needed to be built out facially to have a better position as compared to the abutment teeth. A Uveneer template (Ultradent Products) was used with an additional increment of composite to add facial contour to the pontic (Figures 16 and 17). Final contouring was accomplished using carbide composite finishing burs (SS White Burs) and all-surface polishing discs (A.S.A.P. [CLINICIAN’S CHOICE Dental Products]) (Figure 18).
Figures 19 and 20 show occlusal and facial views of the OVC after finishing to the pontic portion of the bridge. Figure 21 is a facial view of the completed OVB.
Utilizing the OVC and techniques demonstrated herein, this option offers the dentist an economical alternative to costly CAD/CAM or indirect laboratory restorations. These restorations can be easily maintained and repaired throughout the lifetime of the restoration. With the OVC now available in both a hybrid ceramic and lithium disilicate, dentists can choose between 2 quality one-visit restorative choices for their patients.
Disclosure: Dr. Lowe reports no disclsoures.