The single tooth replacement can be one of the most challenging situations in dentistry. This restoration can be made even more unpredictable if the existing tooth has bone loss, unique coloring and/or contour issues. High smile lines and thin periotypes can also make the tooth replacement very challenging. For years, single implants have been placed and restored in a two-stage surgical procedure. More recently, there is a developing body of scientific evidence that supports the immediate placement of implants at the time of extraction followed by placement of an immediate temporary crown. 1-7 Ribeiro et al reported in 2008 that there is no significant difference in success rates between immediate nonfunctional implants and those placed with the traditional delayed protocol. 4 Furthermore, Garber et al reported a success rate of 96.3% during non-functional loading which is similar to delayed values of 94.4% to 100%.2 This article will present a case report to discuss some of the implant design principles of NobelActive™ (Nobel Biocare, Gothenburg, Sweden) that have been created to enhance initial stability, esthetics, and temporization. These new implant design features have made the clinical efficacy of immediate placement and temporization of the single tooth implant a highly predictable procedure.
In 1952, Brnemark made a serendipitous discovery concerning the integration of titanium and bone. 8 Since then, there have been many changes in titanium implant design, composition, and surface texture in search of the Holy Grail for the ideal dental implant. The search continues for an implant that will replace the missing tooth while meeting the expectations of the patient and having a clini- cal success that is equal to or better then past results. Immediate placement of an implant can be defined as the placement of the dental implant immediately after the extraction of the natural tooth. The immediate temporization of the dental implant is defined as the placement of a tooth shaped temporary abutment with crown at time of placement of the implant. Wang et al have further classified Immediate implant loading as an implant restorative technique in which the “implant supported restoration is placed into occlusal loading within at least 48 hours after implant placement.”6
There are many indications and contraindications for immediate placement of implants. Gapski et al. listed four broad categories of factors that influence efficacy of immediate implant loading. 1) Surgery-related factors, 2) Host-related factors relating to bone type, quantity and healing ability. 3) Implantrelated factors relating to implant design and 4) Occlusion-related factors. 5
Block has listed some of contraindications as the following: purulent discharge in the area, periapical pathology, uncontrolled diabetes, and lack of bone.9 On the other hand, Arlin et al reported a high level of success with immediate placement if the failing tooth is “devoid of purulent exudate, there is a healthy collar of gingival tissue around the tooth, and minimal lucency is present at the apex of the tooth to be extracted.”10 Holst et al cautioned surgeons that there are several restorative and biological factors that can influence the clinical success of immediately loaded implants. 11 They cited “quality and quantity of bone, occlusal forces, surgical technique, implant design providing the post-surgical stabilization, number and distribution of implants, and rigid splinting of the provisional restoration. Polizzi et al further cautioned that if periodontal disease is the primary cause of the tooth extraction then it may be wise to wait for healing prior to implant placement.12 Clearly, there are many factors to consider; thus each case must be evaluated by the surgeon both prior to surgery and at the time of immediate implant placement.
There are many benefits of immediately placing and loading an implant at time of extraction. Some benefits are listed below:
1. One surgical procedure instead of two;
2. No temporary partial required;
3. Soft tissues are usually maintained;
4. Wound contraction issues are minimal;
5. Patients like the procedure being completed in one stage;
6. Patients finds eating foods the same as natural tooth during healing.
There are two key timelines for implant stability. These two phases have been called primary stability and secondary stability. All of the aforementioned preclinical issues being equal, when the osteotomy is prepared and the implant is placed the “primary stability” is directly affected by the design of the implant. The design of the body and threads are critical for creating an implant that will “grab” once the implant is placed. After the implant is secured, the biologic principles of osseointegration begin. The bone will begin to heal with osteoblast activity leading to an integration of tita nium with bone and soft tissues. Montes et al reported that there are three possible responses by the host following implant placement. The first two responses are acute or chronic inf lammatory responses to the implant and formation of connective tissue surrounding the implant. Both of these responses can lead to early loss of the implant. The third response occurs when the body biologically accepts the implant through fixation and healing; hence, secondary stability is achieved and it becomes osseointegrated. 13
Micromovement is often cited as a concern when placing immediate implants. The magnitude of force on the implant can improve or diminish the chances of success following immediate placement.3 It has been postulated that if a patient has too much movement of an implant during healing the healing bone will change into fibrous tissue leading to implant failure. Brunski concluded in 1999 that “Excessive interfacial micromotion early after implantation interferes with local bone healing and predisposes to a fibrous tissue interface instead of osseointegration.”14 Misch has reported that healthy teeth “move laterally from 56 to 108 m.”15 It can be extrapolated that parafunctional forces would have higher duration and magnitude on the tooth bone interface leading to even more micromovement.
Other researchers have reported that implant fixation can withstand micromovements of 50 to 150 microns. 2,3 Sekine et al. have found that once an implant has rigid fixation it will still move on average 12 to 66 m in the labio-lingual direction. 16 Brunski 1991, has proposed that a limit of 100 microns for micromovement would be acceptable, however; levels over 150 microns could lead to fibrous encapsulation around the implant. 1,14,15 During immediate placement and subsequent healing the implant design will influence the amount of micromovement that the implant exhibits in the bone. Some researchers have proposed that bone repair may actually be improved if there are micromovements around the implant that are exhibited but kept under 150 microns. 14,15,/sup>
Parafuncional forces should be evaluated for every immediate implant patient. Balshi and Wolfinger reported that 75% of implant failures occurred in patients exhibiting parafunctional habits. 7 Misch lists parafunctional habits as an important force factor when placing implants.16 Avila et al. suggest that early occlusal forces should only be axial. 1 If the centric bite is deep and the patient exhibits excessive tooth wear the initial forces on immediate placed implants may be greater. A tongue thrusting habit may indicate that a traditional 2-stage approach might be more suitable.
When placing an immediate implant, the extraction of the existing tooth or root must be attended to with detail. It is important to perform an atraumatic extraction in an attempt to preserve the buccal plate of bone. Block has reported that 5mm of apical bone is required for immediate placement. 9 Duri
ng placement the immediate implant must usually extend 3mm apical to the extracted tooth or have 3mm of bone contact with the walls of the extraction site. 2,18 “Histological analysis of successful immediate dental implant therapy demonstrates that osseointegration is predictably attainable and efficacious and requires a minimum of 3-5mm of intimate bone to implant contact.”18 The NobelActive implant has been demonstrating excellent initial stability in as little as 3mm of bone.
One could argue that the true merit for any implant system is how the body reacts to the design principles. Fromovich et al20,21 have designed the NobelActive™ implant with the aforementioned issues in mind. For example, the NobelActive™ implant has design concepts to enhance initial stability. Initial stability is usually measured by the implant surgeon at time of placement by “torque testing” the implant. This is a procedure whereby the surgeon places a torque wrench or a calibrated surgical engine on the implant and ensures that the implant can withstand a torque of greater than 35-45 Ncm without further rotation.
Ottoni et al and Wang et al have suggested a value of 32 Ncm would be satisfactory for initial stability.6,22 Garber et al suggested that a more conservative torque value of 40 Ncm would be prudent. 2 The manufacturer of NobelActive™ recommends that the implant can be placed at torque values of 35 to 70 Ncm without incurring pressure necrosis issues. Avila el al. report in a 2007 summary paper that success is equal to two-stage surgery if the implant is placed with “non-traumatic preparation of a good quality bone, rough surface implant placement with an adequate insertion torque greater then 35 N/cm”.1 Hence, the initial torque test stability is usually well above the minimal 35-45 Ncm required for implant temporization and early loading. This initial stability is achievable even in soft Type IV bone.
Thread designs of different implant systems can vary greatly. Many thread designs on other implant systems had either v-shaped, square, roughened beads, or reverse buttress designs. For many of these systems the thread designs have been uniform for the entire length of the implant. In contrast, some other implant designers have introduced thread designs that change at the coronal portion, having smaller threads in this area for soft tissue integration.
Other systems have smooth collars in the coronal area. With the NobelActive™ implant the threads are designed to have high initial torque values. This implant has a dual variable thread design (Fig. 1). The threads have been designed to act as osteotomes Immediately placed NobelActive™ implants have been shown to be “clinically proven and the success rates are equivalent to or better than those of conventional implant protocols.”21
The internal connection of the NobelActive™ implant has some important features adding to implant success (Fig. 2). The hexagonal connection between the internal platform and the abutment is anti-rotational and strong.
Fatigue testing shows that the maximum implant torque strength to failure for the NobelActive™ 3.5 NP is 282 Ncm and the maximum implant torque strength for NobelActive™ 4.3 RP is 452 Ncm. 23 The internal connection also has a coronal seal with bone level condensing the bone as the implant is being place. This is achieved by having large double helix threads with variable pitch diameters. Furthermore, the threads change from a v-shape cutting shape at the apex to a square design as you go coronally. As the implant is placed the changing thread design acts to condense the bone creating excellent stability even in areas exhibiting minimal bone quality or quantity.
The implant site can be conservatively prepared letting the implant act like an osteotome during insertion. The surface of the implant has also been designed for increased stability. Both the implant body and threads are covered by Tiunite™ which has also been shown to enhance initial stability by being rough and osseoconductive. platform shifting. The top of internal portion of the connection has a conical seal that helps to keep a tight biocompatible connection. The interface between the conical seal and the abutment appears to limit any microgap concerns. 23 Vela-Nebot et al have postulated that the location of the microgap can violate biologic width thereby initiating peri-implant bone loss. 24 They speculated that if you use an abutment with lesser diameter then the implant width, this will minimize the invasion of the biologic width. 24 They conclude in their study that there is a statistically significant reduction in crestal bone loss when platform shifting was performed.
The NobelActive™ implant has a built in bone platform shift of 0.05mm.23 The platform shift oc- curs at bone level by having a .25mm smooth collar around the complete top of the abutment to bone platform (Fig. 3). When the single tooth abutment is seated the abutment is .25mm internal to the outer roughened surface. This .25mm smooth collar appears to limit crestal bone loss from infiltration of the biologic width. The bacteria do not appear to infiltrate the conical seal area that appears to also minimize crestal bone loss. Early study results have shown excellent bone stability in the crestal region. 3 For maximum esthetic results the manufacturer recommends that the surgeon place the implant on the level of the buccal bone or 0.5-1mm below.
CASE REPORT
The patient, a 46-year-old male, in excellent health, presented with a failing upper right 1st bicuspid (Fig. 4). He is not taking any medications. The patient wears a biteplate for his bruxism habit. He has had the upper 2nd bicuspids removed with orthodontic correction. Informed consent was discussed and a document was signed. The surgical plan consisted of an immediate extraction of the right 1st bicuspid with immediate placement of a NobelActive RP 15mm 5mm wide dental implant. An allograft was planned at the time of surgery to fill the “jump gap” between the implant and the socket. If the implant had initial stability of greater then 35 Ncm then an immediate temporary abutment was planned. The patient was informed that if the implant did not have an initial stability of above 35 Ncm then an immediate temporary abutment would not be placed.
Models, PA x-rays, and a Panolipse were obtained prior to surgery. A surgical template matching magnification of the Panolipse (available from Nobel Biocare) was placed on the x-ray to plan the placement of the implant. The problematic tooth was extracted using an atraumatic technique to protect the bone for subsequent implant placement. A periotome was inserted into the periodontal ligament space to separate the ligaments (Fig. 5). The root was extracted and measured as part of the planning process for implant placement (Fig. 6). The surgical protocols where followed as recommended by manufacturer. The bone was Type III based on classification by Brnemark el al. 25 A alloplastic bone graft of MBCP (Biometlante) was inserted into the socket (Fig. 7). A 15mm RP 5.0mm wide NobelActive™ implant was placed into the socket and using the surgical driver (Figs. 8 & 9). The implant was placed engaged into the lingual aspect of the socket to assist stability. A torque test revealed an initial stability of 65 Ncm. The manufacturer recommends the implant be torqued between 35 and 70 Ncm.
An immediate temporary abutment was applied to the implant and torqued to 35 Ncm using a multiunit driver with the prosthetic torque wrench (Figs. 10-12). The multiunit driver is included in the Nobel Biocare prosthetic kit. The white plastic temporary abutment cap (included with the immediate temporary abutment) was applied on the hexed temporary abutment to fabricate a temporary crown (Fig. 13). The surface of the temporary plastic cap was roughened with a dia
mond to enhance the mechanical bond. Notice that one side of this white plastic cap is flat to aid in orientation if the pieces happen to pull apart during pickup technique.
During implant planning sessions, an initial impression was taken to fabricate a temporary shell form. The shell form was injected 3/4 full with Luxatemp™ (DMG-Zenith Dental) provisional resin and placed over the immediate temporary abutment in order to the uncured resin out of the surgical area. The acrylic and cap are pulled back off the metal portion of the abutment once the Luxatemp™ provisional material sets. Luxatemp™ flowable is then applied to the areas around the white cap to create the correct emergence profile. When trying the provisional on the temporary abutment post it is important to achieve the appropriate architecture for the crown emergence profile to support the tissue for healing (Fig. 14). Take note to attempt to duplicate the emergence of the natural tooth adjacent to the area. One of the goals of this procedure is to create or maintain gingival papilla. Care must be taken to not extend the flowable over the access to the temporary cap.
Tempbond™ (Kerr) a provie sional cement, was mixed and a very small amount of material was applied into the temporary crown using an explorer. The temporary crown was placed on the abutment and seated in place. The immediate temporary abutment with acrylic crown serves a number of functions. First the patient is usually very pleased that they have their “tooth” back the same day. The temporary abutment also serves to support the soft tissues in buccal ridge and papilla areas for excellent esthetics. These areas can contract during healing if they are not supported. The crown complex is also thought to stimulate bone if forces are not too high or in a non-axial direction. Finally the temporary crown complex acts to maintain a closed system for healing. The system keeps the bone graft and blood clot in place for bone formation. All centric and eccentric contacts where removed from the immediate temporary.
Post-op instructions were discussed. Prescriptions for 500mg amoxicillin q8h for seven days, 600mg ibuprofen stat prn, and a 150ml chlorohexidine rinse were prescribed. The patient was instructed to wait three months for healing. After the healing period, the patient returned to the dental office. An x-ray was taken to see that integration had occurred. There should be an absence of radiolucency around the implant. The immediate temporary abutment was removed using the torque wrench.
During this case a closed tray impression technique was used. The NobelActive™ system has transfer impression copings that are flared to 5mm to match the immediate temporary abutments (Fig. 15A). A flared closed tray impression coping was seated on the implant and an x-ray was taken to confirm seating (Fig. 15B). The tray was tried in to make sure the impression coping had appropriate space for impression material. A small amount of rope wax was placed into the transfer coping hex screw to keep impression material out of this area. This made the reseating of the impression coping easier. A polyvinyl light body impression material was used around the gingival portion of the coping to capture the emergence profile of the papilla. It is important not use too much light body. Medium body impression material was then applied to support the coping body in the custom tray impression. Once the impression was set it was removed and checked for accuracy. A implant replica was attached to the impression coping and the complex was placed back into the impression.
Once the lab received the impression and supporting records they poured up a model using the appropriate implant replica. It is critical that the dental lab uses a gingival model to reproduce the custom work captured in the impression. The gingival model guides the technician during the custom abutment phase. The gingival model is used to place the crown margins on the abutment in the ideal position. Furthermore the contour developed by the immediate temporary abutment is captured and transferred using this gingival model. A custom wax-up of the contour was designed keeping the buccal margin 1mm subgingival and the lingual margin supragingival. A lingual supragingival margin aids in cement cleanup during the crown cementation. During placement of the crown the cement is expressed to the lingual due to the design.
A Procera™ (Nobel Biocare) zirconia custom abutment and a shaded zirconia crown were created using the Forte™ scanner (Fig. 16A). The lab returned the crown in bisque bake for try in and subsequent custom shading.
At try-in the temporary abutment was removed and the zirconia abutment was put into place. The lab provided a red duralay resin orientation jig (Fig. 16B) to aid in the correct placement of the abutment. An x-ray was taken to verify the seating of the abutment (Fig. 17). The jig orients the hexagonal abutment connection into the proper orientation. Furthermore, it makes the holding of small abutments and screw parts easier in the back of the oral cavity. Although the final zirconia abutment could be torqued to 35 Ncm at this point, in this case it was delayed until the patient return from the custom shading at the dental lab. The ceramist finished customization with staining and glazing and the patient returned to the dental office for cementation. Prior to cementation a sterile cotton pellet and resin cement where placed in the screw abutment access hole. Rely-X™ resin cement (3M) was used to cement the crown. Since the lingual margin was supragingival most of the cement was vented to the lingual. The cement was fully cured prior to clean up. A titanium sickle scaler was then be used to clean up the cement. The Serasaw™ (Brasseler) made clean up faster in the interproximal contact areas. The occlusion was checked in centric for heavy bite contacts and all lateral interferences were removed (Fig. 18). The forces on the crown were light in centric occlusion. Working and non-working interferences where checked again after cementation. Polishing of adjustments was made using a Brasseler Porcelain polishing kit. The patient’s biteplate was adjusted to make sure it fit over the dental implant crown.
Follow-up x-rays and photos were taken at eight months to evaluate the short term crestal bone loss and esthetics of the implant placement (Figs. 19 & 20).
Discussion
The NobelActive™ implant design offers a useful system for immediate placement and temporization at the time of extraction. The hexagonal anti-rotational connection with the conical seal and built in bone platform shift helps to prevent crestal bone loss. The large pitch variable thread design provides excellent initial stability. High torque test values can be achieved in minimal bone. The torque value of up to 70 Ncm aids to assist the restorative dentist to immediately temporize the implant eliminating second stage surgery. It has been shown that adjacent papilla and peri-implant tissues will be better supported using an immediate temporization.2 The NobelActive™ implant system appears to have some very promising design features to aid in immediate implant placement and temporization.
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Dr. Scott MacLean is a fellow of the American College of Dentists, the Pierre Faucard Academy, and the Academy of Dentistry International. He teaches Implantology part-time at the Dalhousie University Dental School. Dr. MacLean lectures internationally on topics such as digital photography, soft tissue lasers, zirconia based restorations, and dental implants. He teaches part-time at Dalhousie in the Implant Experience course.
Disclosure
Dr. S. MacLean lectures for Nobel Biocare on implantology and restorative
Acknowledgement
All lab procedures were carried out by Prodent Laboratory in Halifax, NS.
Oral Health welcomes this original article.
References
1. Avila G, Galindo P , Rios H, and Wang HL Immediate Implant Loading: Current Status From Available Literature Implant Dentistry Sept 2007 vol 6 num 3 p235-241
2. Garber DA, Salama H, Salama MA. Two stage versus one-stage – Is there really a controversy? J Periodontol. 2001;72;417-421
3. Glauser R, Zembic A, Ruhstaller P, Windisch S. Five year results of implants with an oxidized surface placed predominantly in soft quality bone and subjected to immediate occlusal loading. J Prosthet Dent. 2007;97 (suppl): S. 59 – 68.
4. Ribeiro et al. Success Rate of Immediate Nonfunctional loaded single-tooth implants: Immediate versus delayed implantation. Implant Dentistry vol 17, num 1, March 2008, pp109-112
5. Gapski R, Wang HL, Mascarenhas P, et al. Critical review of immediate implant loading. Clinical Oral Implants Research. 2003;14:515-527.
6. Wang H, Ormianer Z, Patti A. et a Consensus conference on immediate loading: The single tooth and partial edentulous areas. Implant Dent 2006; 15:324-333.
7. Balshi TJ, Wolfinger GJ. Immediate loading of Branemark implants in edentulous mandibles: a preliminary report. Implant Dent. 1997;6:83-88.
8. AAID – History of Dental Implants http://www.aaid-implant.org/about/Press_Room/History_and_ Background. html
9. Block, MS, “Color Atlas of Dental Implant Surgery”, 2nd edition. Copyright 2007 Saunders, pp 189-199
10. Arlin ML. Immediate placement of osseointegrated dental implants into extraction sockets: advantages and case reports. Oral Health 1992;82:19-20,23-24,26.
11. Holst, S., Geiselhoeringer, H., Wichman, M. and Holst, A. I. The Effects of provisional restoration type on micromovement of implants JPD vol 100 Sept 2008 pp 172-180
12. Polizzi et al. “Immediate and delayed implant placement into extraction sockets: a 5-year report, Clin Implant Dent Relat Res 2000; 2(2):93-9
13. Montes, C. et al. Failing Factors Associated with Osseointegrated Dental Implant loss. Implant Dentistry vol16, Num 4, Dec 2007 PP404-410
14. Brunski, J. B., In vivo bone response to biomechanical loading at the bone/dental-implant interface. Adv Dent Res, 1999. 13: p. 99-119.
15. Szmuckler-Moncler S, Salama, H. Reingewirtz Y., Dubruille JH. Timing of loadingand effects on micromotion on bone-dental implant interface: review of experimental literature. J Biomed Mater Res 1998; 43:192-203
16. Misch, C. “Contemporary Implant Dentistry”, 1nd edition, p186
17. Sekine H, Komiyama Y, Hotta H, et al: Mobility characteristics and tactile sensitivity of osseointegrated fixture supporting systems. In van Steenberghe D, editor: Tissue integration in oral maxillofacial reconstruction, Amsterdam, 1986, Elsevier.
18. Saad el al. Preservation of soft tissue contours with immediate screw-retained provisional implant crown JPD 2007 pp 329-332
19. McNutt, M & Chou C., Current Trends in Immediate Osseous Dental Implant Case Selection Criteria,
Journal of Dental Education Vol 67(8) 20. http://www1.nobelbiocare.com/en/implant-solutions/products/nobelactive/science.aspx
21. Evaluation of NobelActive™ Implants. Five-year randomized controlled prospective multicenter study in 12 centers. Clinical Research Department, Nobel Biocare Services AG.
22. Ottoni JM, Oliveira ZF, Mansini R, et al. Correlation between placement torque and survival of single-tooth implants. Int J Oral Maxillofac Implants. 2005; 20:769-776.
23. The NobelActive™ Technical Story http://www1.nobelbiocare.com/Images/NobelActive% 20Technic al%20Story%20GB%2015May08_tcm57-10947.pdf
24. Vela-Nebot, X. Rodriguez-Ciurana, X. Rodado-Alonso, C. Benefits of an Implant Platform Modification Technique to Reduce Crestal Bone Resorption. Implant Dentistry, vol 15, num 3 pp 313-316
25. Brnemark P-I, Lekholm U and Zarb GA, Albrektsson T (editors), Tissue-Integrated Prostheses. Quintessence Publishing Co. 1985, p. 202.
———
The single tooth replacement can be one of the most challenging situations in dentistry
———
After the implant is secured, the biologic principles of osseointegration begin
———
A tongue thrusting habit may indicate that a traditional 2-stage approach might be more suitable
———
One could argue that the true merit for any implant system is how the body reacts to the design principles
———
The implant site can be conservatively prepared letting the implant act like an osteotome during insertion
———
The problematic tooth was extracted using an atraumatic technique to protect the bone for subsequent implant placement
———
Once the lab received the impression and supporting records they poured up a model using the appropriate implant replica
———
In 1952, Brnemark made a serendipitous discovery concerning the integration of titanium and bone
