- Email: [email protected]
Virtual-Designed and Computer-Milled Implant Abutments
J Oral Maxillofac Surg 63:22-32, 2005, Suppl 2
Virtual-Designed and Computer-Milled Implant Abutments George Priest, DMD* Computer-designed and -generated implant abutments will fundamentally change the present restorative protocols for implant dentistry. Standard implant prosthetic techniques rely on implant level impressions and costly casting technology for component fabrication. Many dentists are uncomfortable making implant level impressions and resort to time-consuming conventional techniques of intraoral abutment preparation or do not offer implants as a treatment alternative. Implant abutments generated by computer-aided design and computer-aided manufacturing (CAD/CAM) are more precise than those created using traditional casting technology. This increased accuracy has specific application to implant dentistry, where precision of components may affect implant longevity, prosthetic success, and ease of restoration. Three current CAD/ CAM implant abutment systems are reviewed, including an innovative digital system which eliminates the need to make implant level impressions. After placing an encoded healing abutment, an impression is made at the healing abutment level. The resulting cast is optically scanned and, using a CAD/CAM system, a patient specific definitive abutment is created. The encoded healing abutment is not removed until delivery of the abutment and final prosthesis. The ease and precision of making implant impressions at the healing abutment level, followed by patient-specific computer-generated abutments presents several benefits: restorative dentists rely less on conventional dental techniques to restore implants, inaccuracies of casting technology are virtually eliminated, laboratory technicians are freed to concentrate on higher level activities, and ultimately dentists are more likely to embrace implants as a preferred treatment option for their patients. This cutting edge technology of computer-assisted implant impressions and computer-generated abutments will likely replace traditional implant restorative protocols and become the standard for implant dentistry in the foreseeable future. © 2005 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 63:22-32, 2005, Suppl 2 Computer-designed and -generated abutments for implant restorations will fundamentally transform the present restorative protocols for implant dentistry. Computer-aided design and computer-aided manufacturing (CAD/CAM) technology is rapidly supplanting traditional labor intensive laboratory methods for implant abutment fabrication. The lost wax technique, a mainstay of prosthetic laboratory procedures and a principal method of implant abutment fabrication, was introduced to dentistry in 1907.1 The accuracy of this process is limited by the expansion and contraction of impression materials, gypsum, wax, casting investment, and alloy.2 In the early 1970s, CAD/CAM technology quickly began replacing conventional manufacturing processes
in commercial uses, particularly aerospace and automotive applications.3,4 In 1971, Francois Duret introduced the CAD/CAM process to restorative dentistry5 and, in 1983, he produced the first CAD/CAM dental restoration.6 Other researchers, including Aoki, Rekow and Caudill,7-9 were instrumental in developing this technology for dental systems. Brandestini and Mörmann, in 1985, then used this process to develop CERAC (Siron, Bensheim, Germany), one of the first commercial CAD/CAM dental system for making ceramic inlays.10 Dental applications of CAD/CAM technology in dentistry remained restricted to finished ceramic restorations, such as inlays and crowns, for nearly 2 decades. Beginning in the 1990s, its applicability expanded into restorative aspects of implant dentistry by transforming the manufacturing process of implant abutments.
*Private Practice, Atlanta, GA; Consultant, 3i, Implant Innovations, Inc., Palm Beach, FL. Address correspondence and reprint requests to Dr Priest: 999 Peachtree St, NE, Suite 795, Atlanta, GA 30309; e-mail: [email protected]
Traditional Implant Abutment Options: Stock or Cast Custom Typically, dentists select either stock or cast custom abutments for implant restorations. Stock and cast custom abutments are available in titanium and noble metal alloys as well as ceramics such as alumina
© 2005 American Association of Oral and Maxillofacial Surgeons
0278-2391/05/6309-0204$30.00/0 doi:10.1016/j.joms.2005.05.158
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GEORGE PRIEST
Table 1. A COMPARISON OF STOCK, CAST CUSTOM, AND CAD/CAM IMPLANT ABUTMENTS
Restorative Procedure
Stock Abutment
Cast Custom Abutment
CAD/CAM Abutment
Anesthesia Handpiece needed Oral obstructions Retraction cord Die trimming Patient experience Delegate to lab/assistant Appointment time Contours Interface Abutment inventory Lab cost Profitability
Yes Yes Yes Yes Yes Uncomfortable No More Limited Good Yes Low Low
No No No No No Pleasant Yes Less Ideal Good Yes Higher Higher
No No No No No Pleasant Yes Less Ideal Excellent No In Between Highest
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
and zirconium. The preparation of stock abutments is subtractive in the sense that material is removed to create their final form. Traditional custom abutments are formed by additive methods of waxing and casting. Advantages and disadvantages of stock and custom abutments are described below (Table 1). STOCK ABUTMENTS: ADVANTAGES AND DISADVANTAGES
The primary advantage of stock abutments is their lower initial cost. They may be prepared either intraorally or extraorally; and if implants are ideally positioned, preparation time can be minimal. If, on the other hand, stock abutments require extensive modifications, the benefit of low initial cost may be outweighed by the additional production time the dentist or laboratory technician must invest in the preparation. Dentists preparing stock abutments intraorally face several obstacles that are not experi-
enced with extraoral preparation. Patients must be anesthetized, conventional retraction procedures and impression making are necessary, and dentists are encumbered by intraoral structures. The patient experience is thus longer and less pleasant than with extraoral preparation. A major disadvantage of stock abutments is related to their shape. Most are cylindrical in configuration for the entire length of the component, not just at the implant platform (Figs 1-3). Antirotational facets incorporated on the surface of stock abutments become obliterated with any significant reduction. To prevent rotation of the definitive crown, the dentist or technician must often add grooves to stock abutments. However, because ceramic stock abutments are usually thin with little bulk of material on the vertical walls, additional reduction may compromise their strength.
FIGURE 1. A stock ceramic abutment will be prepared for an allceramic crown.
FIGURE 2. From the occlusal aspect, the circular configuration of the stock abutment is apparent.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 3. Because of the cylindrical configuration, the completed preparation must also be essentially circumferential. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
FIGURE 4. Apical to the finish line, the cylindrical ceramic abutment retains a relatively straight profile. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 6. Radiographically, the abrupt angulation between the ceramic abutment and ceramic crown are evident. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
A second problem related to cylindrical design is the gingival transition from the implant abutment to the overlying crown or retainer.11 In the vertical plane, the emergence profile cannot begin at the implant platform, but at the finish line created on the stock abutment (Fig 4). The unprepared portion of the abutment is relatively straight and parallel to the implant, and the crown margin must then emerge acutely at the finish line, resulting in a stepped emergence profile (Figs 5-7). In the occlusal plane, the round stock abutment does not match the anatomic gingival configuration of the tooth it replaces. As in the vertical plane, the transition begins at the prepared gingival margin, which may be abrupt. Third, when implant alignment is less than ideal, preparation of stock abutments may obliterate much of the abutment material, thereby compromising re-
FIGURE 5. The resultant crown emergence profile from the abutment to the crown is not confluent, but stepped to achieve normal facial contours at the gingival level.
FIGURE 7. Although abutment contours are less than ideal, a pleasing esthetic result is noticed 2 weeks after abutment and crown seating.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
GEORGE PRIEST
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FIGURE 8. An endodontically treated and crowned central incisor has fractured at the gingival level.
FIGURE 10. The emergence profile begins at the implant platform and proceeds smoothly to the metal ceramic crown.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
tention. Stock abutments with fixed angulation may not correspond with the actual correction needed.12 The above listed disadvantages emphasize the difficulty in customizing stock abutments and may result in less than ideal crown contours and insufficient support for optimum soft tissue esthetics.
(Figs 13-17).14 If angulation correction is required, the custom abutment can be precisely configured. Custom abutments provide better potential than stock abutments for ideal crown contours and peri-implant soft tissue support leading to optimal esthetic results. Fabrication of cast custom abutments that relies on conventional waxing, casting, milling, and finishing techniques results in 3 disadvantages. The first is higher initial cost, including the expense of the implant component and the time consuming and labor intensive procedures of waxing, casting, milling, and finishing. When the definitive crown or prosthesis is factored in, the total fees may dissuade some dentists from selecting this option of abutment fabrication. Premachined abutment platforms exhibit an additional advantage of an abutment/implant interface with a superior fit compared to completely cast abutments.15 The second disadvantage of custom abutment fabrication is that the investing, casting, and
CAST CUSTOM ABUTMENTS: ADVANTAGES AND DISADVANTAGES
The primary advantage of a cast custom abutment is that it is made specifically for the patient’s individual tooth that the corresponding implant replaces.13 The custom abutment is generally contoured like the preparation of the missing tooth and is thus inherently antirotational (Figs 8, 9). The gingival transition of the custom abutment begins at the implant platform (Figs 10-12). Therefore, the emergence profile is confluent from the implant to the abutment and to the crown in both the vertical and occlusal planes
FIGURE 9. Following implant placement and integration, a cast custom abutment is fabricated in the laboratory.
FIGURE 11. Normal soft and hard tissue contours are restored.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 12. On radiographic examination, the demarcation between the abutment and crown interface are barely perceptible. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
finishing process may alter the CAD/CAM created abutment-implant interface. The third disadvantage is that the quality of the abutment is dependent on the knowledge and experience of the technician fabricating the component. A laboratory technician may deliver a finely milled abutment or a crudely finished part that compromises the function and esthetics of the final restoration.
CAD/CAM Custom Implant Abutments Considerable technical innovation and financial investment have been required to shift from manufacturing systems designed for mass production of identical components (such as stock abutments and cast custom abutment platforms) to sophisticated systems that could deliver abutments specifically made for
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 14. Removal of the healing abutment reveals a peri-implant profile that is also circular. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
each individual restoration in a cost efficient and timely manner.16 The hurdle of providing completely individualized abutments has been overcome and several implant manufacturers now offer CAD/CAM patient–specific abutment systems.17 Custom abutments created with CAD/CAM technology have the potential to provide the advantages of both stock and laboratory processed custom abutments without the disadvantages (Table 1). First, like laboratory-made abutments, CAD/CAM abutments are specific for each patient. However, the results are much more consistent. The technician’s learning curve is less steep than that for handmade components. The technician controls the abutment design using CAD software that incorporates parameters to assist him or her. The virtually designed abutment is
FIGURE 13. A round healing abutment is placed on an implant that will restore a maxillary right second premolar.
FIGURE 15. A cast custom abutment and metal ceramic crown replace the missing premolar.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
GEORGE PRIEST
FIGURE 16. After several weeks, the abutment was removed to demonstrate anatomic soft tissue form developed by the custom abutment. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 18. Unique encoded healing abutments are read by an optical scanner to determine implant size, hex position, implant location, and soft tissue levels. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
electronically transferred to a CAM milling apparatus that creates the abutment from a block of the selected abutment material. Most of the inherent dimensional inaccuracies of waxing, investing, and casting are eliminated. Casting of titanium, in particular, is complex in a dental laboratory. CAD/CAM machining results in a homogenous mass of titanium with optimum material properties.18 CAD/CAM custom abutments are machined to the precision that immovable implants require. Unlike stock or cast custom abutments, the abutment surfaces of CAD/CAM abutments are not subjected to the above-mentioned manipulation processes after machining. Although Vigalo et al19 showed that the abutment surface of a stock or cast custom abutment is not significantly affected when laboratory steps are meticulously followed, Byrne et al15 found that heat-induced changes of premachined abutment platforms during casting procedures re-
duced the contact between the abutments and corresponding retaining screws. From a review of implant abutment preparation techniques, Wee et al20 concluded that dentists and laboratories should select implant/abutment interfaces that demonstrate superior fit, and they should follow laboratory procedures that would not induce further discrepancies. Because their interfaces do not require manipulation after machining, CAD/CAM abutments have the potential to provide the most accurate fit of any abutment type. This increased accuracy of CAD/CAM abutments has specific application to implant dentistry, where precision of components may affect implant longevity, prosthetic success, and ease of restoration. Ideally, ceramic implant abutments should be machined from completely sintered blocks of material, but hard ceramic materials used for abutment fabrication cannot be efficiently machined with conventional grind-
FIGURE 17. Twelve years after placement, gingival sulcular form remains intact.
FIGURE 19. Both fractured maxillary central incisors will be replaced with implant restorations.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 22. After removing the index, the surgeon places encoded healing abutments. FIGURE 20. After implant placement, the surgeon seats direct implant impression copings.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
ing reduces the work they must perform to create implant abutments. ing tools. Therefore, they are presently milled in the green body state before firing.16 When compared with a stock and cast custom abutment, the cost of a CAD/CAM implant abutment presently lies somewhere between the two. This expense is likely to decrease over time as CAD/CAM systems for abutment fabrication become commonplace and the high initial capital outlays made by manufacturers are distributed over a growing number of abutments sold. Conversely, costs of manpower and labor-intensive laboratory processes are likely to escalate, thereby increasing the cost of prepared stock abutments or handmade cast custom abutments. Additionally, considering the shortage of qualified laboratory technicians,21 CAD/CAM manufactur-
CURRENTLY AVAILABLE CAD/CAM ABUTMENT SYSTEMS
The Atlantis Abutment (Atlantis Components, Inc, Cambridge, MA), milled in titanium alloy, has been commercially available since the early 1990s.22,23 Abutment design and fabrication is outsourced to the Atlantis facility and may be prescribed by the implant surgeon, restorative dentist, or laboratory technician. Atlantis provides a second duplicate abutment to give dentists the option of placing a provisional crown on the first abutment and a definitive crown on the second.24 The second abutment may also be used as a laboratory die. Gold anodized coatings have been added to improve gingival tones and to impart more natural shades through all-ceramic restorations. Atlantis abutments are purported to have excellent marginal detail and anatomic gingival contours.25 A single impression or implant positioning index26 can be
FIGURE 21. The surgeon surrounds the impression copings with heavy-bodied impression material to complete an implant placement index.
FIGURE 23. Implants have integrated and soft tissue has matured.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
GEORGE PRIEST
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FIGURE 26. An optical scanner at the 3i facility translates the data to a virtual image of the encoded abutments, teeth, and surrounding soft tissue. FIGURE 24. A heavy-bodied polyvinylsiloxane impression is made of the encoded healing abutments by the restoring dentist. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
made at the time of implant surgery. Ensuing tissue recession during soft tissue healing may necessitate hand modifications of the abutment margin before crown fabrication.25 Procera (Nobel Biocare, Yorba Linda, CA), initially developed for titanium and aluminum oxide copings for conventional crowns,27 has recently added implant abutments to their line of CAD/CAM components.28 With this system, the abutment is virtually designed by the local laboratory using a Procera digital scanning system and software purchased from Nobel Biocare. The information is electronically transmitted to a Procera facility where the virtual abutment is milled and returned to the local laboratory. The dentist has the option to receive both a CAD/CAM abutment and CAD/CAM titanium or ceramic coping using this same system. Fit and marginal adaptation have proven to be comparable with cast restora-
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
tions.29-31 Short-term results indicate that Procera ceramic abutments clinically perform as well as or better than other abutment types.32 Implant Innovations, Inc, (Palm Beach Gardens, FL) has developed a new line of CAD/CAM components under the umbrella of ArchiTECH PSR (for patient specific restoration). Encode, the aptly named custom abutment segment of the system, incorporates codes or facets on the occlusal surface of the corresponding healing abutments (Fig 18). An optical scanner interprets these codes to determine implant size, hex position, implant location, and soft tissue levels. Similar to the Atlantis Abutment System protocol, the surgeon may make an index of implant positions at the time of implant surgery or uncovering (Figs 19-21). This index is later used by the local laboratory to make a cast for seating the final Encode abutments and fabricating the definitive restorations. The sur-
FIGURE 25. The dentist’s local laboratory pours the cast in die stone and sections the encoded healing abutments.
FIGURE 27. Patient-specific final abutments are created virtually on a computer monitor.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 28. Completed titanium custom abutments are returned from the 3i facility to the local laboratory where they are placed on a cast created from the surgical implant positioning index.
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 30. The restorative dentist secures the Encode final abutments to specified torque. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
geon then places the Encode healing abutments (Fig 22). Following implant integration and soft tissue maturation, the restorative dentist makes only 1 impression of the Encode healing abutments in place, eliminating the need to make a restorative phase implant level impression (Figs 23, 24). The local laboratory technician pours and sections the cast (Fig 25) and the entire Encode process is outsourced to Implant Innovations, Inc. An optical scanner reads and translates the codes embedded in the healing abutments (Fig 26). This data is transferred to the CAD software, the implant abutments are virtually designed (Fig 27), and the CAM milling apparatus produces the final titanium abutments. The completed abutments are returned to the local laboratory and definitive resto-
rations are made on a cast created from the surgeon’s positioning index (Figs 28, 29). The Encode healing abutments are removed by the restorative dentist at delivery of the abutment and final prostheses. Patient specific final abutments are seated (Fig 30) and definitive crowns are placed (Fig 31). The particular advantage of this approach is that a novice restorative dentist, who is not completely comfortable with implant procedures, is not required to make an implant level impression. Because the restorative dentist makes a healing abutment level impression of mature soft tissue levels, marginal form and depth of the definitive Encode abutment is precise, minimizing the likelihood of modifications before crown fabrication. The author’s initial experience with 43 Encode abutments over a 9 month period from August 2004 to April 2005 has been quite positive. From 1 to 10 abutments were seated in 18 patients. Abutment design and marginal form have been ideal, requiring no
FIGURE 29. Close examination of the abutments shows smooth marginal chambers and excellent abutment/analog interfaces.
FIGURE 31. Definitive metal ceramic restorations are cemented to place.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 32. An Encode final abutment is made to restore a maxillary second premolar.
FIGURE 34. The junction between the titanium implant and titanium Encode final abutment are not discernable.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
hand modifications of height, contour, or gingival margins of final abutments upon receipt. Because 1 incorrectly sized healing abutment was placed and scanned, the resulting final abutment was remade. Thirty-seven restorations completed on casts from implant level impressions required considerably less proximal and occlusal adjustments than the 6 restorations finished on casts from surgical indices. The abutment/implant interfaces were clinically precise and imperceptible on radiographic examination (Figs 32-34). For these reasons, the author has transitioned exclusively to the Encode Restorative System when selecting titanium alloy abutments. For laboratory technicians, CAD/CAM implant abutments will virtually eliminate the inaccuracies of casting technology. Computer keyboards will replace hand instruments to become the tools for design and creation of dental restorations. Given the shortage of laboratory
technicians, outsourced CAD/CAM implant abutments will free qualified technicians to focus on their artistry rather than labor intensive procedures. Because implant abutments are manufactured in a matter of minutes, overall turnaround time is decreased between the laboratory and restorative dentist. Because CAD/CAM abutment fabrication is outsourced to an authorized facility, dental laboratories do not have to invest in sophisticated technology to provide this superior service. Using computer-generated implant abutments, restorative clinicians will rely less on conventional dental techniques to restore implants. Simplified restorative protocols of CAD/CAM abutment systems make implant dentistry easier, particularly for the novice restorative implant dentist. Improved marginal fit and ideal contours of CAD/CAM custom abutments provide greater stability and more consistent implant esthetics. CAD/ CAM systems also reduce the cost of custom abutment fabrication. Intraoral implant scanning technology will eliminate the need for implant impressions, further distancing dentistry from outdated restorative procedures as they incorporate these systems into their routine implant protocols. As dentists embrace CAD/CAM innovations that simplify implant dentistry and create predictable and stable implant interfaces, they are more likely to recommend and deliver implants as their preferred option of tooth replacement for patients.
References
FIGURE 33. A metal ceramic crown is cemented on the final abutment. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
1. Taggart WH: A new and accurate method of making gold inlays. Dent Cosmos 49:1117, 1907 2. Gelbard S, Aoskar Y, Zalkind M, et al: Effect of impression materials and techniques on the marginal fit of metal casting. J Prosthet Dent 71:1, 1994 3. Calamia JR: Advances in computer-aided design and computeraided manufacture technology. Curr Opin Cosmet Dent 67, 1994
32 4. Duke ES: The status of CAD/CAM in restorative dentistry. Compendium 22:968, 2001 5. Duret F, Blouin JL, Duret B: CAD CAM in dentistry. J Amer Dent Assoc 117:715, 1988 6. Duret F, et al: Demonstration pratique de l’empreinte optique, 9c Entretiens de Granciere. Paris, 21 Septembre 1983 7. Rekow ED, Speidel TM, Erdman AG: Computer-aided automatic production of posterior dental restorations. J Dent Res 65:317, 1986 (abstr 1336) 8. Fujita T, Aoki H, Yamamura M, et al: A computer-aided approach to construction of coronal restorations. Bull Kanagawa Dent Coll 13:57, 1985 9. Caudell R: Computer-Integrated Dentistry. New Harbor, Academy of Dentistry, 1988 10. Brandestini M, Mörmann W: Computer-machined ceramic inlays. In vitro marginal adaptation. J Dent Res 64:208, 1985 (abstr 305) 11. Daftary F: Dentoalveolar morphology: Evaluation of natural root form versus cylindrical implant fixtures. Pract Periodont Aesthet Dent 9:469, 1997 12. Reid PE, Burke TM: Customized implant abutments: Technical notes. Implant Dent 3:243, 1994 13. Lewis SG, Llamas D, Avera S: The UCLA abutment: A four-year review. J Prosthet Dent 67:509, 1992 14. Papazian S, Morgano SM: A laboratory procedure to facilitate the development of an emergence profile with a custom implant abutment. J Prosthet Dent 79:232, 1998 15. Byrne D, Houston F, Cleary R, et al: The fit of cast and premachined implant abutments. J Prosthet Dent 80:184, 1998 16. Mehl A, Hickel R: Current state of development and perspectives of machine-base production methods for dental restorations. Int J Comput Dent 2:9, 1999 17. Preston JD, Duret F: CAD/CAM in dentistry. Oral Health 87:17, 1997 18. Rekow ED: CAD/CAM in dentistry: A historical perspective and view of the future. JCDA 58:283, 1992 19. Vigalo P, Majzoub Z, Cordioli GP: Measurement of the dimensions and abutment rotational freedom of gold machined 3i UCLA-type abutments in the as-received condition, after casting with a noble metal alloy and porcelain firing. J Prosthet Dent 84:548, 2000
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS 20. Wee AG, Aquilino SA, Schneider RL: Strategies to achieve fit in implant prosthodontics: A review of the literature. Int J Prosthodont 12:167, 1999 21. Robson JA: The future of a dentist’s lab support. ADA News 35:4, 2004 22. Osario J: Use of the Atlantis Abutment in restorative practice speeds time to function and aesthetics. Dental Implantol Update 11:57, 2000 23. Kerstein RB, Castellucci F, Osorio J: Ideal gingival form with computer-generated permanent healing abutments. Compendium 21:793, 2000 24. Kerstein RB, Osorio J: Utilizing computer-generated duplicate titanium custom abutments to facilitate intraoral and laboratory implant prosthesis fabrication. Pract Proced Aesthet Dent 15: 311, 2003 25. Ganz SD: Computer-milled patient-specific abutments: Incredible quality with unprecedented simplicity. Pract Proced Aesthet Dent 15:37, 2003 (suppl 8) 26. Hochwald DA: Surgical template impression during stage I surgery for fabrication of a provisional restoration to be placed at stage II surgery. J Prosthet Dent 66:796, 1991 27. Andersson M, Oden A: A new all-ceramic crown: Dense-sintered, high-purity alumina coping with porcelain. Acta Odont Scand 51:59, 1993 28. Van Dooren E: Restoring implants with Procera technology and optimal tissue management. Pract Proced Aesthet Dent 15:23, 2003 (suppl 8) 29. Lovgren R, Andersson B, Bergovist S, et al: Clinical evaluation of ceramic veneered titanium restorations according to the Procera technique. Swed Dent J 21:1, 1997 30. Sulaiman F, Chai J, Jameson LM, et al: A comparison of the marginal fit of In-Ceram, IPS Empress, and Procera crowns. Int J Prosthodont 10:478, 1997 31. Lang LA, Sierraalta M, Hoffensperger M, et al: Evaluation of the precision of fit between the Procera custom abutment and various implant systems. Int J Oral Maxillofac Implants 18:652, 2003 32. Henriksson K, Jemt T: Evaluation of custom-made Procera ceramic abutments for single-implant tooth replacement: A prospective 1-year follow-up study. Int J Prosthodontics 16: 626, 2003
Virtual-Designed and Computer-Milled Implant Abutments George Priest, DMD* Computer-designed and -generated implant abutments will fundamentally change the present restorative protocols for implant dentistry. Standard implant prosthetic techniques rely on implant level impressions and costly casting technology for component fabrication. Many dentists are uncomfortable making implant level impressions and resort to time-consuming conventional techniques of intraoral abutment preparation or do not offer implants as a treatment alternative. Implant abutments generated by computer-aided design and computer-aided manufacturing (CAD/CAM) are more precise than those created using traditional casting technology. This increased accuracy has specific application to implant dentistry, where precision of components may affect implant longevity, prosthetic success, and ease of restoration. Three current CAD/ CAM implant abutment systems are reviewed, including an innovative digital system which eliminates the need to make implant level impressions. After placing an encoded healing abutment, an impression is made at the healing abutment level. The resulting cast is optically scanned and, using a CAD/CAM system, a patient specific definitive abutment is created. The encoded healing abutment is not removed until delivery of the abutment and final prosthesis. The ease and precision of making implant impressions at the healing abutment level, followed by patient-specific computer-generated abutments presents several benefits: restorative dentists rely less on conventional dental techniques to restore implants, inaccuracies of casting technology are virtually eliminated, laboratory technicians are freed to concentrate on higher level activities, and ultimately dentists are more likely to embrace implants as a preferred treatment option for their patients. This cutting edge technology of computer-assisted implant impressions and computer-generated abutments will likely replace traditional implant restorative protocols and become the standard for implant dentistry in the foreseeable future. © 2005 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 63:22-32, 2005, Suppl 2 Computer-designed and -generated abutments for implant restorations will fundamentally transform the present restorative protocols for implant dentistry. Computer-aided design and computer-aided manufacturing (CAD/CAM) technology is rapidly supplanting traditional labor intensive laboratory methods for implant abutment fabrication. The lost wax technique, a mainstay of prosthetic laboratory procedures and a principal method of implant abutment fabrication, was introduced to dentistry in 1907.1 The accuracy of this process is limited by the expansion and contraction of impression materials, gypsum, wax, casting investment, and alloy.2 In the early 1970s, CAD/CAM technology quickly began replacing conventional manufacturing processes
in commercial uses, particularly aerospace and automotive applications.3,4 In 1971, Francois Duret introduced the CAD/CAM process to restorative dentistry5 and, in 1983, he produced the first CAD/CAM dental restoration.6 Other researchers, including Aoki, Rekow and Caudill,7-9 were instrumental in developing this technology for dental systems. Brandestini and Mörmann, in 1985, then used this process to develop CERAC (Siron, Bensheim, Germany), one of the first commercial CAD/CAM dental system for making ceramic inlays.10 Dental applications of CAD/CAM technology in dentistry remained restricted to finished ceramic restorations, such as inlays and crowns, for nearly 2 decades. Beginning in the 1990s, its applicability expanded into restorative aspects of implant dentistry by transforming the manufacturing process of implant abutments.
*Private Practice, Atlanta, GA; Consultant, 3i, Implant Innovations, Inc., Palm Beach, FL. Address correspondence and reprint requests to Dr Priest: 999 Peachtree St, NE, Suite 795, Atlanta, GA 30309; e-mail: [email protected]
Traditional Implant Abutment Options: Stock or Cast Custom Typically, dentists select either stock or cast custom abutments for implant restorations. Stock and cast custom abutments are available in titanium and noble metal alloys as well as ceramics such as alumina
© 2005 American Association of Oral and Maxillofacial Surgeons
0278-2391/05/6309-0204$30.00/0 doi:10.1016/j.joms.2005.05.158
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GEORGE PRIEST
Table 1. A COMPARISON OF STOCK, CAST CUSTOM, AND CAD/CAM IMPLANT ABUTMENTS
Restorative Procedure
Stock Abutment
Cast Custom Abutment
CAD/CAM Abutment
Anesthesia Handpiece needed Oral obstructions Retraction cord Die trimming Patient experience Delegate to lab/assistant Appointment time Contours Interface Abutment inventory Lab cost Profitability
Yes Yes Yes Yes Yes Uncomfortable No More Limited Good Yes Low Low
No No No No No Pleasant Yes Less Ideal Good Yes Higher Higher
No No No No No Pleasant Yes Less Ideal Excellent No In Between Highest
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
and zirconium. The preparation of stock abutments is subtractive in the sense that material is removed to create their final form. Traditional custom abutments are formed by additive methods of waxing and casting. Advantages and disadvantages of stock and custom abutments are described below (Table 1). STOCK ABUTMENTS: ADVANTAGES AND DISADVANTAGES
The primary advantage of stock abutments is their lower initial cost. They may be prepared either intraorally or extraorally; and if implants are ideally positioned, preparation time can be minimal. If, on the other hand, stock abutments require extensive modifications, the benefit of low initial cost may be outweighed by the additional production time the dentist or laboratory technician must invest in the preparation. Dentists preparing stock abutments intraorally face several obstacles that are not experi-
enced with extraoral preparation. Patients must be anesthetized, conventional retraction procedures and impression making are necessary, and dentists are encumbered by intraoral structures. The patient experience is thus longer and less pleasant than with extraoral preparation. A major disadvantage of stock abutments is related to their shape. Most are cylindrical in configuration for the entire length of the component, not just at the implant platform (Figs 1-3). Antirotational facets incorporated on the surface of stock abutments become obliterated with any significant reduction. To prevent rotation of the definitive crown, the dentist or technician must often add grooves to stock abutments. However, because ceramic stock abutments are usually thin with little bulk of material on the vertical walls, additional reduction may compromise their strength.
FIGURE 1. A stock ceramic abutment will be prepared for an allceramic crown.
FIGURE 2. From the occlusal aspect, the circular configuration of the stock abutment is apparent.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 3. Because of the cylindrical configuration, the completed preparation must also be essentially circumferential. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
FIGURE 4. Apical to the finish line, the cylindrical ceramic abutment retains a relatively straight profile. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 6. Radiographically, the abrupt angulation between the ceramic abutment and ceramic crown are evident. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
A second problem related to cylindrical design is the gingival transition from the implant abutment to the overlying crown or retainer.11 In the vertical plane, the emergence profile cannot begin at the implant platform, but at the finish line created on the stock abutment (Fig 4). The unprepared portion of the abutment is relatively straight and parallel to the implant, and the crown margin must then emerge acutely at the finish line, resulting in a stepped emergence profile (Figs 5-7). In the occlusal plane, the round stock abutment does not match the anatomic gingival configuration of the tooth it replaces. As in the vertical plane, the transition begins at the prepared gingival margin, which may be abrupt. Third, when implant alignment is less than ideal, preparation of stock abutments may obliterate much of the abutment material, thereby compromising re-
FIGURE 5. The resultant crown emergence profile from the abutment to the crown is not confluent, but stepped to achieve normal facial contours at the gingival level.
FIGURE 7. Although abutment contours are less than ideal, a pleasing esthetic result is noticed 2 weeks after abutment and crown seating.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
GEORGE PRIEST
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FIGURE 8. An endodontically treated and crowned central incisor has fractured at the gingival level.
FIGURE 10. The emergence profile begins at the implant platform and proceeds smoothly to the metal ceramic crown.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
tention. Stock abutments with fixed angulation may not correspond with the actual correction needed.12 The above listed disadvantages emphasize the difficulty in customizing stock abutments and may result in less than ideal crown contours and insufficient support for optimum soft tissue esthetics.
(Figs 13-17).14 If angulation correction is required, the custom abutment can be precisely configured. Custom abutments provide better potential than stock abutments for ideal crown contours and peri-implant soft tissue support leading to optimal esthetic results. Fabrication of cast custom abutments that relies on conventional waxing, casting, milling, and finishing techniques results in 3 disadvantages. The first is higher initial cost, including the expense of the implant component and the time consuming and labor intensive procedures of waxing, casting, milling, and finishing. When the definitive crown or prosthesis is factored in, the total fees may dissuade some dentists from selecting this option of abutment fabrication. Premachined abutment platforms exhibit an additional advantage of an abutment/implant interface with a superior fit compared to completely cast abutments.15 The second disadvantage of custom abutment fabrication is that the investing, casting, and
CAST CUSTOM ABUTMENTS: ADVANTAGES AND DISADVANTAGES
The primary advantage of a cast custom abutment is that it is made specifically for the patient’s individual tooth that the corresponding implant replaces.13 The custom abutment is generally contoured like the preparation of the missing tooth and is thus inherently antirotational (Figs 8, 9). The gingival transition of the custom abutment begins at the implant platform (Figs 10-12). Therefore, the emergence profile is confluent from the implant to the abutment and to the crown in both the vertical and occlusal planes
FIGURE 9. Following implant placement and integration, a cast custom abutment is fabricated in the laboratory.
FIGURE 11. Normal soft and hard tissue contours are restored.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 12. On radiographic examination, the demarcation between the abutment and crown interface are barely perceptible. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
finishing process may alter the CAD/CAM created abutment-implant interface. The third disadvantage is that the quality of the abutment is dependent on the knowledge and experience of the technician fabricating the component. A laboratory technician may deliver a finely milled abutment or a crudely finished part that compromises the function and esthetics of the final restoration.
CAD/CAM Custom Implant Abutments Considerable technical innovation and financial investment have been required to shift from manufacturing systems designed for mass production of identical components (such as stock abutments and cast custom abutment platforms) to sophisticated systems that could deliver abutments specifically made for
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 14. Removal of the healing abutment reveals a peri-implant profile that is also circular. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
each individual restoration in a cost efficient and timely manner.16 The hurdle of providing completely individualized abutments has been overcome and several implant manufacturers now offer CAD/CAM patient–specific abutment systems.17 Custom abutments created with CAD/CAM technology have the potential to provide the advantages of both stock and laboratory processed custom abutments without the disadvantages (Table 1). First, like laboratory-made abutments, CAD/CAM abutments are specific for each patient. However, the results are much more consistent. The technician’s learning curve is less steep than that for handmade components. The technician controls the abutment design using CAD software that incorporates parameters to assist him or her. The virtually designed abutment is
FIGURE 13. A round healing abutment is placed on an implant that will restore a maxillary right second premolar.
FIGURE 15. A cast custom abutment and metal ceramic crown replace the missing premolar.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
GEORGE PRIEST
FIGURE 16. After several weeks, the abutment was removed to demonstrate anatomic soft tissue form developed by the custom abutment. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 18. Unique encoded healing abutments are read by an optical scanner to determine implant size, hex position, implant location, and soft tissue levels. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
electronically transferred to a CAM milling apparatus that creates the abutment from a block of the selected abutment material. Most of the inherent dimensional inaccuracies of waxing, investing, and casting are eliminated. Casting of titanium, in particular, is complex in a dental laboratory. CAD/CAM machining results in a homogenous mass of titanium with optimum material properties.18 CAD/CAM custom abutments are machined to the precision that immovable implants require. Unlike stock or cast custom abutments, the abutment surfaces of CAD/CAM abutments are not subjected to the above-mentioned manipulation processes after machining. Although Vigalo et al19 showed that the abutment surface of a stock or cast custom abutment is not significantly affected when laboratory steps are meticulously followed, Byrne et al15 found that heat-induced changes of premachined abutment platforms during casting procedures re-
duced the contact between the abutments and corresponding retaining screws. From a review of implant abutment preparation techniques, Wee et al20 concluded that dentists and laboratories should select implant/abutment interfaces that demonstrate superior fit, and they should follow laboratory procedures that would not induce further discrepancies. Because their interfaces do not require manipulation after machining, CAD/CAM abutments have the potential to provide the most accurate fit of any abutment type. This increased accuracy of CAD/CAM abutments has specific application to implant dentistry, where precision of components may affect implant longevity, prosthetic success, and ease of restoration. Ideally, ceramic implant abutments should be machined from completely sintered blocks of material, but hard ceramic materials used for abutment fabrication cannot be efficiently machined with conventional grind-
FIGURE 17. Twelve years after placement, gingival sulcular form remains intact.
FIGURE 19. Both fractured maxillary central incisors will be replaced with implant restorations.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 22. After removing the index, the surgeon places encoded healing abutments. FIGURE 20. After implant placement, the surgeon seats direct implant impression copings.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
ing reduces the work they must perform to create implant abutments. ing tools. Therefore, they are presently milled in the green body state before firing.16 When compared with a stock and cast custom abutment, the cost of a CAD/CAM implant abutment presently lies somewhere between the two. This expense is likely to decrease over time as CAD/CAM systems for abutment fabrication become commonplace and the high initial capital outlays made by manufacturers are distributed over a growing number of abutments sold. Conversely, costs of manpower and labor-intensive laboratory processes are likely to escalate, thereby increasing the cost of prepared stock abutments or handmade cast custom abutments. Additionally, considering the shortage of qualified laboratory technicians,21 CAD/CAM manufactur-
CURRENTLY AVAILABLE CAD/CAM ABUTMENT SYSTEMS
The Atlantis Abutment (Atlantis Components, Inc, Cambridge, MA), milled in titanium alloy, has been commercially available since the early 1990s.22,23 Abutment design and fabrication is outsourced to the Atlantis facility and may be prescribed by the implant surgeon, restorative dentist, or laboratory technician. Atlantis provides a second duplicate abutment to give dentists the option of placing a provisional crown on the first abutment and a definitive crown on the second.24 The second abutment may also be used as a laboratory die. Gold anodized coatings have been added to improve gingival tones and to impart more natural shades through all-ceramic restorations. Atlantis abutments are purported to have excellent marginal detail and anatomic gingival contours.25 A single impression or implant positioning index26 can be
FIGURE 21. The surgeon surrounds the impression copings with heavy-bodied impression material to complete an implant placement index.
FIGURE 23. Implants have integrated and soft tissue has matured.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
GEORGE PRIEST
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FIGURE 26. An optical scanner at the 3i facility translates the data to a virtual image of the encoded abutments, teeth, and surrounding soft tissue. FIGURE 24. A heavy-bodied polyvinylsiloxane impression is made of the encoded healing abutments by the restoring dentist. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
made at the time of implant surgery. Ensuing tissue recession during soft tissue healing may necessitate hand modifications of the abutment margin before crown fabrication.25 Procera (Nobel Biocare, Yorba Linda, CA), initially developed for titanium and aluminum oxide copings for conventional crowns,27 has recently added implant abutments to their line of CAD/CAM components.28 With this system, the abutment is virtually designed by the local laboratory using a Procera digital scanning system and software purchased from Nobel Biocare. The information is electronically transmitted to a Procera facility where the virtual abutment is milled and returned to the local laboratory. The dentist has the option to receive both a CAD/CAM abutment and CAD/CAM titanium or ceramic coping using this same system. Fit and marginal adaptation have proven to be comparable with cast restora-
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
tions.29-31 Short-term results indicate that Procera ceramic abutments clinically perform as well as or better than other abutment types.32 Implant Innovations, Inc, (Palm Beach Gardens, FL) has developed a new line of CAD/CAM components under the umbrella of ArchiTECH PSR (for patient specific restoration). Encode, the aptly named custom abutment segment of the system, incorporates codes or facets on the occlusal surface of the corresponding healing abutments (Fig 18). An optical scanner interprets these codes to determine implant size, hex position, implant location, and soft tissue levels. Similar to the Atlantis Abutment System protocol, the surgeon may make an index of implant positions at the time of implant surgery or uncovering (Figs 19-21). This index is later used by the local laboratory to make a cast for seating the final Encode abutments and fabricating the definitive restorations. The sur-
FIGURE 25. The dentist’s local laboratory pours the cast in die stone and sections the encoded healing abutments.
FIGURE 27. Patient-specific final abutments are created virtually on a computer monitor.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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FIGURE 28. Completed titanium custom abutments are returned from the 3i facility to the local laboratory where they are placed on a cast created from the surgical implant positioning index.
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS
FIGURE 30. The restorative dentist secures the Encode final abutments to specified torque. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
geon then places the Encode healing abutments (Fig 22). Following implant integration and soft tissue maturation, the restorative dentist makes only 1 impression of the Encode healing abutments in place, eliminating the need to make a restorative phase implant level impression (Figs 23, 24). The local laboratory technician pours and sections the cast (Fig 25) and the entire Encode process is outsourced to Implant Innovations, Inc. An optical scanner reads and translates the codes embedded in the healing abutments (Fig 26). This data is transferred to the CAD software, the implant abutments are virtually designed (Fig 27), and the CAM milling apparatus produces the final titanium abutments. The completed abutments are returned to the local laboratory and definitive resto-
rations are made on a cast created from the surgeon’s positioning index (Figs 28, 29). The Encode healing abutments are removed by the restorative dentist at delivery of the abutment and final prostheses. Patient specific final abutments are seated (Fig 30) and definitive crowns are placed (Fig 31). The particular advantage of this approach is that a novice restorative dentist, who is not completely comfortable with implant procedures, is not required to make an implant level impression. Because the restorative dentist makes a healing abutment level impression of mature soft tissue levels, marginal form and depth of the definitive Encode abutment is precise, minimizing the likelihood of modifications before crown fabrication. The author’s initial experience with 43 Encode abutments over a 9 month period from August 2004 to April 2005 has been quite positive. From 1 to 10 abutments were seated in 18 patients. Abutment design and marginal form have been ideal, requiring no
FIGURE 29. Close examination of the abutments shows smooth marginal chambers and excellent abutment/analog interfaces.
FIGURE 31. Definitive metal ceramic restorations are cemented to place.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
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GEORGE PRIEST
FIGURE 32. An Encode final abutment is made to restore a maxillary second premolar.
FIGURE 34. The junction between the titanium implant and titanium Encode final abutment are not discernable.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
hand modifications of height, contour, or gingival margins of final abutments upon receipt. Because 1 incorrectly sized healing abutment was placed and scanned, the resulting final abutment was remade. Thirty-seven restorations completed on casts from implant level impressions required considerably less proximal and occlusal adjustments than the 6 restorations finished on casts from surgical indices. The abutment/implant interfaces were clinically precise and imperceptible on radiographic examination (Figs 32-34). For these reasons, the author has transitioned exclusively to the Encode Restorative System when selecting titanium alloy abutments. For laboratory technicians, CAD/CAM implant abutments will virtually eliminate the inaccuracies of casting technology. Computer keyboards will replace hand instruments to become the tools for design and creation of dental restorations. Given the shortage of laboratory
technicians, outsourced CAD/CAM implant abutments will free qualified technicians to focus on their artistry rather than labor intensive procedures. Because implant abutments are manufactured in a matter of minutes, overall turnaround time is decreased between the laboratory and restorative dentist. Because CAD/CAM abutment fabrication is outsourced to an authorized facility, dental laboratories do not have to invest in sophisticated technology to provide this superior service. Using computer-generated implant abutments, restorative clinicians will rely less on conventional dental techniques to restore implants. Simplified restorative protocols of CAD/CAM abutment systems make implant dentistry easier, particularly for the novice restorative implant dentist. Improved marginal fit and ideal contours of CAD/CAM custom abutments provide greater stability and more consistent implant esthetics. CAD/ CAM systems also reduce the cost of custom abutment fabrication. Intraoral implant scanning technology will eliminate the need for implant impressions, further distancing dentistry from outdated restorative procedures as they incorporate these systems into their routine implant protocols. As dentists embrace CAD/CAM innovations that simplify implant dentistry and create predictable and stable implant interfaces, they are more likely to recommend and deliver implants as their preferred option of tooth replacement for patients.
References
FIGURE 33. A metal ceramic crown is cemented on the final abutment. George Priest. Virtual-Designed/Milled Implant Abutments. J Oral Maxillofac Surg 2005.
1. Taggart WH: A new and accurate method of making gold inlays. Dent Cosmos 49:1117, 1907 2. Gelbard S, Aoskar Y, Zalkind M, et al: Effect of impression materials and techniques on the marginal fit of metal casting. J Prosthet Dent 71:1, 1994 3. Calamia JR: Advances in computer-aided design and computeraided manufacture technology. Curr Opin Cosmet Dent 67, 1994
32 4. Duke ES: The status of CAD/CAM in restorative dentistry. Compendium 22:968, 2001 5. Duret F, Blouin JL, Duret B: CAD CAM in dentistry. J Amer Dent Assoc 117:715, 1988 6. Duret F, et al: Demonstration pratique de l’empreinte optique, 9c Entretiens de Granciere. Paris, 21 Septembre 1983 7. Rekow ED, Speidel TM, Erdman AG: Computer-aided automatic production of posterior dental restorations. J Dent Res 65:317, 1986 (abstr 1336) 8. Fujita T, Aoki H, Yamamura M, et al: A computer-aided approach to construction of coronal restorations. Bull Kanagawa Dent Coll 13:57, 1985 9. Caudell R: Computer-Integrated Dentistry. New Harbor, Academy of Dentistry, 1988 10. Brandestini M, Mörmann W: Computer-machined ceramic inlays. In vitro marginal adaptation. J Dent Res 64:208, 1985 (abstr 305) 11. Daftary F: Dentoalveolar morphology: Evaluation of natural root form versus cylindrical implant fixtures. Pract Periodont Aesthet Dent 9:469, 1997 12. Reid PE, Burke TM: Customized implant abutments: Technical notes. Implant Dent 3:243, 1994 13. Lewis SG, Llamas D, Avera S: The UCLA abutment: A four-year review. J Prosthet Dent 67:509, 1992 14. Papazian S, Morgano SM: A laboratory procedure to facilitate the development of an emergence profile with a custom implant abutment. J Prosthet Dent 79:232, 1998 15. Byrne D, Houston F, Cleary R, et al: The fit of cast and premachined implant abutments. J Prosthet Dent 80:184, 1998 16. Mehl A, Hickel R: Current state of development and perspectives of machine-base production methods for dental restorations. Int J Comput Dent 2:9, 1999 17. Preston JD, Duret F: CAD/CAM in dentistry. Oral Health 87:17, 1997 18. Rekow ED: CAD/CAM in dentistry: A historical perspective and view of the future. JCDA 58:283, 1992 19. Vigalo P, Majzoub Z, Cordioli GP: Measurement of the dimensions and abutment rotational freedom of gold machined 3i UCLA-type abutments in the as-received condition, after casting with a noble metal alloy and porcelain firing. J Prosthet Dent 84:548, 2000
VIRTUAL-DESIGNED/MILLED IMPLANT ABUTMENTS 20. Wee AG, Aquilino SA, Schneider RL: Strategies to achieve fit in implant prosthodontics: A review of the literature. Int J Prosthodont 12:167, 1999 21. Robson JA: The future of a dentist’s lab support. ADA News 35:4, 2004 22. Osario J: Use of the Atlantis Abutment in restorative practice speeds time to function and aesthetics. Dental Implantol Update 11:57, 2000 23. Kerstein RB, Castellucci F, Osorio J: Ideal gingival form with computer-generated permanent healing abutments. Compendium 21:793, 2000 24. Kerstein RB, Osorio J: Utilizing computer-generated duplicate titanium custom abutments to facilitate intraoral and laboratory implant prosthesis fabrication. Pract Proced Aesthet Dent 15: 311, 2003 25. Ganz SD: Computer-milled patient-specific abutments: Incredible quality with unprecedented simplicity. Pract Proced Aesthet Dent 15:37, 2003 (suppl 8) 26. Hochwald DA: Surgical template impression during stage I surgery for fabrication of a provisional restoration to be placed at stage II surgery. J Prosthet Dent 66:796, 1991 27. Andersson M, Oden A: A new all-ceramic crown: Dense-sintered, high-purity alumina coping with porcelain. Acta Odont Scand 51:59, 1993 28. Van Dooren E: Restoring implants with Procera technology and optimal tissue management. Pract Proced Aesthet Dent 15:23, 2003 (suppl 8) 29. Lovgren R, Andersson B, Bergovist S, et al: Clinical evaluation of ceramic veneered titanium restorations according to the Procera technique. Swed Dent J 21:1, 1997 30. Sulaiman F, Chai J, Jameson LM, et al: A comparison of the marginal fit of In-Ceram, IPS Empress, and Procera crowns. Int J Prosthodont 10:478, 1997 31. Lang LA, Sierraalta M, Hoffensperger M, et al: Evaluation of the precision of fit between the Procera custom abutment and various implant systems. Int J Oral Maxillofac Implants 18:652, 2003 32. Henriksson K, Jemt T: Evaluation of custom-made Procera ceramic abutments for single-implant tooth replacement: A prospective 1-year follow-up study. Int J Prosthodontics 16: 626, 2003