More and more clinicians these days are moving from cementable restorations to screw retained. Even though the demand is higher, a screw retained crown is not indicated in every situation. Many times the implant is placed where it has to go, only to leave the angulation such that a titanium abut- ment and cementable crown are the only options. The new Angulated Screw Channel System from Nobel Procera is changing that limitation and opening up new possibilities.
A Better Angle
The patient is a 43-year old female. Other than a penicillin allergy, her medical and social histories are noncontributory to her treatment. Tooth number 3 has an extensive treatment history dating back 25 plus years, including restorations and eventually endodontic treatment. The tooth was never restored with an indirect full coverage restoration after root canal therapy. Several years later the tooth fractured and was deemed non-restorable. The tooth was extracted sometime around 1992. The patient then wore a unilateral single tooth removal partial denture to re- place number 3. This appliance was worn for about 5 years before the patient stopped wearing it completely. For 15-20 years, the edentulous number 3 area was not restored.
Opting now for treatment, options were reviewed with the patient along with risks and benefits. The patient elected to have an implant placed and restored with a single unit crown. Due to bone resorption from the amount of time lapse and anatomical limitations of the inferior border of the right maxillary sinus cavity, sinus augmentation would be necessary. Sinus augmentation was performed and a Nobel Biocare Active RP
5.0 x 10 implant was placed. Once osseointegration was complete, the implant was ready to be restored. Due to anatomical concerns, the implant was placed at a bucco-palatal angle. After the impression coping was placed it was easy to see that, if a screw retained restoration was to be used, the access opening would be located on the top of the occlusal third of the buccal surface at the buccal groove. In this particular case, it was going to be next to impossible to do a screw retained restoration, which would be contrary to our desired optimal treatment. Disappointingly, it seemed that most likely a stock angled abutment with a cement retained restoration would have to be utilized.
Upon case analysis in the laboratory, it was determined that this would be a good opportunity to use the Nobel Procera ASC (angulated screw channel). The ASC system would allow up to 25 degrees of angulation change, the use of porcelain fused to zirconia, and thusly achieve the more desirable screw retained op tion. With its unique Omnigrip driver and screw head (both with blue markings for easy identification), the access hole could be moved into a more favorable location and still easily engage the implant.
The case was scanned and then designed with the Nobel software. A zirconia abutment on a titanium platform was made. The titanium base is “friction-fit” and can be easily removed for porcelain firing. Porcelain was applied in the standard fare using Vita VM9 porcelains.
The crown was seated into the implant just as easily as any other screw retained crown. The esthetics and function of the crown were not compromised as a result of utilizing the ASC. Interproximal contacts were adequate and very limited occlusal adjustment was necessary. The single unit crown has maximum intercuspation occlusion with no excursive contacts. The crown was easily torqued to 35Ncm utilizing the Nobel Biocare Omnigrip. As can be seen from the photos, the screw access opening is now at the central fossa and can be easily accessed with normal operating procedures.
The concerns over implant failures due to un- seen cement being left behind, the ease of retrieval, and the technological advancements have raised, or arguably returned, screw retained restorations as the “go to” restorative choice. New options like the Nobel Procera Angulated Screw Channel System allow clinicians to place highly esthetic porcelain fused to zirconia screw retained restorations in situations where implant angulation would have earlier demanded a titanium abutment and cementable crown.
The authors would like to thank Jason T. Beck, D.D.S., M.D. and Mr. Jim Lawlor for their contributions.
Dr. Clark Giddings is a general dentist with a practice in Stephenville, TX. He gradated from the University of Okla-homa with a degree in Business Management, then completed his den- tal training at the University of Texas Health Science Center in San
Antonio. He is a member of the ADA, TDA, and Fort Worth District Dental Society
Kyle Swan, CDT is co- owner and managing partner of Functional Esthetics, Inc. Kyle has been a ceramist for over 20 years and, together with his partner Phil Watkins CDT and their team of excellent technicians, enjoys being an integral part of the inter-
disciplinary team. Kyle is a member of the American Equilibration Society, the AACD, and is a contributor to Inside Dental Technology.