SECTION 3 – INDUSTRY NEWS AND RESEARCH

Q: I have an implant with cracked internal hex. What is the best way to remove it? Should I use a trephine-drill (where can I get one ?) or can I unscrew an integrated implant without too much bone damage?

A: In 1990, we began offering the Screw-Vent implant in both commercially pure titanium and titanium alloy. Six years later, we widened the neck of the small-diameter Screw-Vent from 3.5mmD to 3.7mmD, which required the incorporation of a countersink section at the top of each length-specific drill. Core-Vent/Paragon has also have offered wide-diameter, internally threaded implants with 4.5mmD necks since 1986. To date, we have not received a single fracture report with these wide-diameter implants. To maximize strength, Paragon has offered all diameters of the Screw-Vent implant only in titanium alloy since 1997. The following guidelines are provided in Paragon's product warranty:

To prevent fractures of implants and/or abutments, avoid conditions of overloading caused by:

1. Inadequate number of implants to support the restoration.


2. Inadequate implant lengths and/or diameters.


3. Excessive cantilever lengths.


4. Incomplete abutment seating.


5. Custom abutments angled greater than 30°.


6. Occlusal interferences causing excessive lateral forces.


7. Patient parafunction, such as bruxing.


8. Improper casting procedures.


9. Inadequate or non-passive prosthesis fit.


10. Excessive crown/root ratio.


11. Using non-Paragon abutments on Paragon implants.


12. Trauma or accidents to the implants.

In the rare cases where fracture does occur, we have a removal tool available. Visit our product page to view and order our Removal Tool for Broken Screw-type Implants [IRT]:
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Additional Comment from Dr. Murray L. Arlin: Paragon Implant Company has a self-tapping tool that threads into the implant in a counterclockwise direction. Once the tool bottoms out inside the implant, continued turning counterclockwise under applied force will break the osseointegration and unscrew the implant from the jaw. I recently did this with a Screw-Vent where there was a lost cemented abutment. I cleaned out the cement within the implant with a bur, and the removal tool cut through the residual cement and grabbed into the titanium inner walls of the implant.

I have had 6 internal hex implants that experienced "hex splits" out of 600 placed over the last 5 to 13 years. They occurred within a 1- to 3-year period after the prosthetic restoration. All cases were full-arch, fixed restorations incorporating 6 implants with a 10 to 12 mm cantilever. Five of the 6 hex splits were at the terminal implant location, while in one case the 2 terminal implants on the same side split. None of the implants were wide diameter and none occurred on any implants manufactured after 1996 when the walls were increased by 2/10ths of a mm.

Q: I attended a course given by the guys of BioHorizons. They say that they have found that the initial crestal resorption during the first year in dental implants is related to the design of the neck of the implant. I asked what role bacteria plays in that phenomenon, and they said NONE. I am not very convinced with that answer. What do you think about the presence of bacteria in the implant-abutment interface or design of the neck of the implant as the cause of initial crestal bone resorption?

A: To the question of whether the presence of bacteria in the implant-abutment interface or the neck design of the implant is the main cause of crestal bone loss, the answer is most likely NEITHER.

Crestal bone loss is initially related to how thick the labial plate is at the time of implant placement. Long-term, it is determined by the intensity and/or the direction of the load on the implant. Yes, bacteria from wobbly implant/abutment joints can contribute to bone loss, as Citron has shown. However, bone loss also occurs with the ITI implant, which has no joint connection near the crest of the bone. As for implant design, implants with wider necks, and which often requiring countersinking, can also contribute to bone loss because of the stress concentration at the crest. Carl Misch and I lectured in Venezuela several years ago and he revealed his secret for eliminating radiographic bone loss with the BioHorizons implant. In the maxilla, he inserts the implant several millimeters below the crest and then waits for bone loss to occur --- before taking the xray. The bone loss occurs anyway, but it looks like the implant is level with the crest on the xray. There is nothing about the design of his implant that should or will reduce the amount of crestal bone loss any more than any other implant. This is unfortunately the only marketing story Carl and BioHorizons can come up to differentiate their implant from competitors...and it is a bogus.

FOR MORE INFORMATION ON MY PERSPECTIVE OF BIOHORIZONS, CHECK OUT THIS LINK:
../research/controversy/contro1_pt09-1.html

Q: I am sorry to bother you with a personal e-mail like this but I need some help. I am treatment planning a large restorative case with Advent implants. Basically the patient is edentulous in the mandible and I will be restoring her with a hybrid prosthesis using 6 implants. I looked through your CD ROM but it does not discuss this type of restoration. I plan on using Advent as a one-stage procedure with an interim denture while she heals. What abutment is best, in your opinion, to restore this type of case? I have done cases like this with Lifecore and Astra but I want to use Paragon products now. Thanks for any information.

A: I checked Paragon's CD-ROM 900-slide series and the complete step-by-step clinical and laboratory procedures are there for screw-retained dentures. Just click onto "restorative manual" on page one, and then onto "bar overdentures." Begin advancing through the web pages from there and you will see the ACT abutment, how it is used to make bars, and then a lot on screw-retained dentures. In addition, on Paragon's website, which is also on the CD-ROM, go to the download page and click on Abutment Selection Guide and you will find the page for screw-retained dentures to see what the parts are. You can select them also on our "click-to-chart" program on the CD-ROM.. Make sure you have Paragon's CDO6 CD-ROM. Here is the link to the Abutment Selection Guide:
http://www.parawebdesign.com/download/prostheticpdf/prthcpage6.pdf

Basically you have two choices ... one is to just attach a gold cylinder (or plastic cylinder) to the analog of the top of the Advent and wax up your framework. Preferably, just attach the ACT screw for the Advent and convert it to an ACT abutment, which has the advantage of having a shorter fixation screw than if you connected directly to the implant. Once you have attached the ACT screw, just take an abutment-level transfer, as if you were doing a bar case. With the Advent, the Implant Extender can be used with the ACT screw for more height.

Q: I tried using the Tapered Screw-Vent for a sinus elevation procedure, but could not completely seat the implant, even with a mallet. Since then, I have used the Micro-Vent implant, then the Micro-Vent2 implant for many years and have been very happy with it. Recently someone mentioned that the Micro-Vent2 is going to be discontinued. Is this true?

A: Thank you for your long-term support. First, we will be making the tapered Micro-Vent2 for well into 2002. Let me correct some misconceptions that you may have about this implant and the Tapered Screw-Vent. The Tapered Screw-Vent does not even have a bone tap made for it, nor is it tapped in with a mallet like the Micro-Vent2. Second, the Tapered Screw-Vent will provide far greater initial stability than the Micro-Vent2 because it is threaded over its entire surface and will expand/compress soft bone if you insert it into a socket prepared with the intermediate drill (i.e. stop at the 2.8mmD drill for the 3.7mmD implant or the 3.8mmD drill for the 4.7mmD implant). If you had problems trying to fully seat the implant, you were most likely trying to elevate the floor of the sinus as you threaded the implant in, thinking that it would lift the floor of the sinus. If you were not through the cortical bone surrounding the sinus, the round end of the Tapered Screw-Vent would stop on the cortical shell around the sinus, with the risk of stripping the threads in the bone. You should drill slowly through the floor of the sinus or tap it up with an osteotome, and then seat the implant as you tent up the membrane. You have been successful with Micro-Vent2 because of its HA coating as much as its design. The tapered Screw-Vent will allow you to load earlier in soft bone and to make stage-one transfer impressions because of its better initial stability.

Q: I read about the Tapered SwissPlus on your website newsletter (#7), and I can agree on many points. However, at this time, I am not ready to make a wholesale switch from ITI to anything else because they work better than anything else I have used. Further, the prosthetic problems are resolvable using a little ingenuity.

In summary, changing implant systems is like changing referral patterns. There needs to be some underlying discontent to want to make a move. I don't have it right now and don't have a sense of urgency or desire to do so, as I did from Friadent and 3i. You are welcome to visit when you are next in Boca. I appreciate your efforts at conversion, but I am not yet interested enough to jump. Why should I, if things are working well enough now?

A: Thank you for reading our newsletter (#7) on the Tapered SwissPlus (../cgi-local/SoftCart.exe/newsletter7/index.html?L+scstore+fcmx3175+977096905) and for your comment that you "can agree on many points." I was not expecting you to "make a wholesale switch from ITI to anything else" and can certainly appreciate that this is "because they work better than anything else [you] have used." The problem is that you are comparing the ITI to the Friadent and 3i, not to the SwissPlus or Tapered SwissPlus. That is the point ...you recognize the advantages of these implants and should be able to conclude that they will solve many of the limitations of the ITI system for which you have learned to accommodate.

You are obviously not adverse to trying new things...you switched from TPS to SLA. The only thing Straumann has shown with SLA is that it has a little higher percentage of bone attachment than TPS. The Buser et al. study (J Biomed Mat Res 1991;25:889-902) reported the difference as not being statistically significant. We have three independent studies showing Paragon's SBM surface has higher percentage of bone contact than TPS (one Belgium study compared SBM to ITI's TPS) and two of the studies showed that SBM even have a higher percentage of bone contact than HA (Louisiana State University). Check out these studies, if surface is what is important to you:
../marat/octaplusnew.htm

Your response, along with several postings on the implant internet chat group, prompted me to give a more compete answer to some of the questions raised by your comments about what is critical for clinical success. I am copying you on my response to the group. Please read it:

I can only devote so much of my time to helping dentists understand the critical factors for achieving clinical success in all qualities of bone, and to understanding the restorative advantages of the products I design. I think I have given you that time and am confident that you understand that the Tapered SwissPlus offers many advantages over what you are using from ITI including:

1. Prosthetic versatility-Can use full contour abutments, angled abutments and custom cast gold abutments connected directly to the top of the implant. Narrow one- and two-piece abutments using the implant shoulder as the margin are also available. The fixture mount is both the straight abutment and the transfer component. The castable sleeve that comes with every narrow solid abutment is both the transfer and the castable sleeve...held in place without overlapping the analog undercut that then requires cutting back of the margins.

2. Increased initial stability-The tapered design will expand or compress soft bone, and the self-tapping design will simplify insertion and further enhance initial stability.

3. Increased strength-The narrow tapered SwissPlus can withstand 100 lbs more compression at 30 degrees than the ITI narrow 3.3mmD implants.

4. Increased surface area-The double lead threads of the Tapered SwissPlus speed insertion, reduce insertion torque and increase surface area by 34% along with the deeper coronal threads of the 4.8mmD Tapered SwissPlus.

5. Bettor oral hygiene-With the full-contour, preparable abutments, the margin of the restoration can follow the contour of the tissue, eliminating deep subgingival cemented margins that often result from using the level shoulder of the implant as the margin.

6. Cost savings to both you and your restorative dentists. For simple posterior restorations, the fixture mount becomes the full-contour abutment. Simply cut off the top square used for insertion and you have an emergence profile abutment that will shape the soft tissue. This will eliminate the need to cement a plastic protective cap on a narrow solid abutment. Furthermore, this "normal" type of implant abutment allows intraoral preparation of the margins, followed by conventional impression procedures (or use the fixture mount as the transfer and prep it on the working cast). You will not only save a substantial amount of money for yourself as you are buy and attach the abutments, but you will also save your restorative dentists considerable money when they need an angled or custom-cast abutment.

In any case, our narrow abutments are less than half the price of Straumann's abutments, so you should consider ordering them for your Straumann implants. For you to focus on only the surface, and then to rely on your belief in the ITI researchers rather than on the validity and significance of the studies themselves is something that I would not have expected from a knowledgeable periodontist. Furthermore, surface consideration is but one factor in optimizing clinical success. Once you have two implants with the same degree of surface roughness (ITI and Paragon), both with research studies showing a high degree of bone attachment, then you need to look at other factors, such as I have described above.

ITI is a mediocre implant, at best, both in quality of manufacturing and in design-even with their addition of my patented internal connection, which they are not fully utilizing. The minimum thread surface, due to the shallowness and roundness of the threads and narrow distance between threads makes predictable osseointegration in soft bone questionable. Certainly, from an early loading standpoint, it is greatly lacking in both surface area and initial stability compared to the Tapered SwissPlus implant.

You state that you do not want to change your referral patterns, but yet you will have to change from the Friadent and 3i products to something to assure clinical success. Why don't you convert these referrals to the Tapered SwissPlus? This will give you the comfort of using something closer to the ITI concept and give them the prosthetics they are more familiar with by using full contour abutments. At the very least, to avoid fractures of their narrow implants, you should be using our narrow platform Tapered SwissPlus implant with a platform that more closely matches that of the ITI standard 4.8 mm platform than their narrow platform with the 1.6 mm high external octagon.

Finally, you state that the "prosthetic problems are resolvable using a little ingenuity." They are completely resolvable by just changing systems. You cannot handhold every restorative dentist, especially the new ones you hope to enlist. Some of the problems are not that easily resolved. For example, when I was in Florida last time, one dentist told me that he had used ITI's plastic castable sleeves that overlap the undercut of the analog. This is how they gain stability during waxing. He said that when he went to dress down the gold flash created by these overextended plastic sleeves, he ruined the restoration. Would you want crowns in your mouth that had been overwaxed and required the technician or dentist to dress back the gold flash to guess where the margins should be? I think you should be leading your restorative dentists to better clinical results, simpler restorative procedures, more esthetic options and increased profits if you want to further expand your implant practice.

Use your success as a springboard, not as a pedestal. Do not be manipulated by ITI's marketing and assurances that, if you use this Swiss system, it will give you more credibility with your restorative dentists. They have effectively used this marketing strategy, buying opinion leaders to lead other professionals to their products. This is the reason they are selling at 80 times earnings. They make enough high profits from the followers to pay their opinion leaders. Nobel Biocare used the same type of marketing strategy for years until they finally had to buy an American company to survive in this country.

THAT IS ALL THE WISDOM AND ADVICE I CAN GIVE YOU. THE REST IS UP TO YOU.

Q: Sargon may be compacting bone when dentists first expand the pods. However, if the implant/bone interface turns into fibrous tissue, as happens when osseointegration is not achieved, the amount of bone lost could be highly variable, depending on the load and the time the nonintegrated implant was left in function. Just how fast IS the downgrowth of fibrous tissue? Could membranes help?

A: I don't think that fibrous tissue necessarily has to grow downward. Bone is calcified fibrous tissue that forms in definite patterns, depending on stress and probably chemical messengers. I think fibrous tissue may occur through stresses, micromovements, etc., that break down the bone. In turn, the bone is "repaired" by replacement with fibrous scar tissue. If that is the case, a membrane probably wouldn't work.

I agree completely that downgrowth of soft tissue is not the issue. Let’s get down to basics. Osseointegration is dependent on the following three factors:

1. Avoid overheating when preparing bone.

2. Achieve initial stability. This can be accomplished with a self-tapping thread or, better yet, a tapered, self-tapping implant, screwed into a straight hole for bone expansion. You don't need expanding pods to accomplish this.

3. Avoid premature loading. The variables of bone density, initial stability, surface roughness, force and direction of initial loading of the implant affects osseointegration success if the implant is not submerged. This is especially true if the implant is immediately loaded.

I think that initial stability and, therefore, the likelihood of success with immediate loading, can be more predictably and effectively achieved with a rough surface (better yet HA surface) on a self-tapping tapered implant, than with expanding pods. If the Sargon idea is that the pods allow you to read the bone and you should only immediately load if the bone is so dense that the pods can't expand, one can determine the density of the bone for immediate loading based on the resistance to drilling or self-tapping.

The Sargon claim of being able to expand the pods to get a second chance at osseointegration is a false claim. The likelihood of achieving success the first time is probably greater if the surface is rougher, the design of the implant allows self-tapping, and especially if the bone is expanded. Sargon has a smooth machined surface and is not self-tapping. One can always just replace the failed implant with a wider one if osseointegration is lost on an immediately loaded solid implant, and then wait for non-loaded healing. With Sargon, one is going to have to remove the crown to expand the pods and then leave it off to avoid further loading. This is just as much a nuisance as replacing the implant, especially if the better surface and self-tapping design can increase the initial stability and, therefore, the likelihood of integration in the first place.

Q: No major company has copied the Sargon concept. Are there better ways to achieve the goal of immediate load, without the concerns of long-term complications from a weakened molly bolt design?

A: The following study confirms that Straumann can not claim earlier loading with SLA compared to TPS. There was no statistical difference between the attachment strength of these two surfaces. The slide of this study is on the CD-ROM under TPS vs. SLA, along with two other studies that show similar results.

Buser D, Nydegger T, Oxland T, Cochran DL, Schenk RK, Hirt HP, Snetivy D, Nolte LP: Interface shear strength of titanium implants with a sandblasted and acid-etched surface: A biomechanical study in the maxilla of miniature pigs. Journal of Biomedical Materials Research 1991;25:889–902:

"The purpose of the present study was to evaluate the interface shear strength of unloaded titanium implants with a sandblasted and acid-etched (SLA) surface in the maxilla of miniature pigs. The two best-documented surfaces in implant dentistry, the machined and the titanium plasma-sprayed (TPS) surfaces served as controls. After 4, 8, and 12 weeks of healing, removal torque testing was performed to evaluate the interface shear strength of each implant type. The results revealed statistically significant differences between the machined and the two rough titanium surfaces (p <. 00001). The machined surface demonstrated mean removal torque values (RTV) between 0.13 and 0.26 Nm, whereas the RTV of the two rough surfaces ranged between 1.14 and 1.56 Nm. At 4 weeks of healing, the SLA implants yielded a higher mean RTV than the TPS implants (1.39 vs. 1.14 Nm) without reaching statistical significance. At 8 and 12 weeks of healing, the two rough surfaces showed similar mean RTVs. The implant position also had a significant influence on removal torque for each implant type primarily owing to differences in density in the per implant bone structure. It can be concluded that the interface shear strength of titanium implants is significantly influenced by their surface characteristics, since the machined titanium surface demonstrated significantly lower RTV in the maxilla of miniature pigs compared with the TPS and SLA surfaces."

Q: It has been reported that, for implants to become osseointegrated, they must heal in the absence of functional loads for 4 to 6 months. However, more and more implant companies have developed systems that promise to address the patient’s demand for uninterrupted or immediate function and esthetics following initial implant placement. How successful have these systems been and what information is available to substantiate these claims?

A: The TPS screw implant sold by Straumann in the 1980s was used with 4 implants in the symphysis, splinted and loaded immediately. Babbush and Kent published on several thousand implants restored this way. It is rapidly becoming accepted methodology again to immediately load implants that are splinted across the midline in edentulous jaws. Schnitman published a 10-year study of Branemark implants immediately loaded. Here he loaded 3 and buried 5 in a number of jaws with the idea that the 3 immediately loaded would fail but provide transitional support. He achieved very high success with both the early and late loaded implants.

Tom Balshi and Bill Becker also published on immediate loading in lower full-arch cases. Dr. Dennis Tarnow of NYU published on immediate loading in both arches. I am presently funding an immediate loading study of one-piece, one-stage ADVENT implants at New York University and University of Pittsburgh. The protocol calls for the placement of 4 implants in the symphysis, two of which are blasted and two are HA coated. Immediately upon suturing, a gold collar, shaped like the collar of a standard two-piece abutment, will be attached to the top of the implant. These gold collars are then joined in the mouth with gold dolder bars cut to length and attached with autopolymerizing acrylic. The assembly is then removed, soldered and returned for attachment to the implants within 24 hours. An overdenture will then be attached. This splints the one-stage implants for greater stability, saves the cost of transfers, analogs and the inaccuracy of indirect fabrication of bars.

If you wanted to make a screw-retained temporary bridge to splint the implants immediately, a titanium sleeve could be attached to the top of each implant and the provisional prosthesis could be fabricated by using an omnivac shell made from the patient's old denture. The provisional prosthesis could then be relieved to accommodate the titanium, and relined directly in the mouth to incorporate the sleeves. A better way may be to do a transfer impression immediately upon inserting the implants and fabricate the temporary bridge indirectly. I know a number of dentists who use this method for unilateral bridges in the lower jaw where bone quality is good, but there is very little documentation to support this concept yet. I believe it will prove to be reliable with at least 3 implants splinted and kept out of full occlusion. The key to immediate loading is good quality bone and/or splinting around the arch.

Q: How can Paragon advocate preparing abutments directly in the patient's mouth?

Eriksson et al. (J Prosthet Dent 1983;5[1]) documented that a temperature rise of 10 degrees C for one minute in bone is sufficient to cause tissue injury. The extreme heat generated by the cutting procedure can cause irreversible tissue damage and threaten osseointegration.

A: Paragon has advocated intraoral abutment preparation without incident since 1981, provided an intermittent cutting technique with diamond burs under copious irrigation is utilized. A pilot thermographic analysis conducted by McCullagh et al. (Pract Period Aesthetic Dent 1998;10[9]) found that non-irrigated, high-speed preparation of five different abutment types with a medium-grit diamond burs in 60-second durations produced temperature increases that ranged from 13.2 to 31.3 degrees C. In contrast, Gross et al. (Int J Oral Maxillofac Implants 1995;10[2]:207-212) compared heat generation at the implant surface during abutment preparation with tungsten carbide and diamond burs in a high-speed, turbine handpiece with standard turbine coolant. Cutting in 15-second increments reduced heat generation by 75% compared to continuous cutting for 30 seconds. During periods of continuous cutting for 30 seconds, tungsten carbide burs caused a mean temperature increase of 2 degrees C (maximum = 4.7 degrees C), versus 1 degree C (maximum = less than 2 degrees) for diamond burs caused a mean temperature increase. Gross et al. conclude that abutment reduction with medium-grit diamond burs using intermittent pressure and normal turbine coolant is unlikely to cause an interface-temperature increase sufficient to cause irreversible bone damage and compromise osseointegration.

Q: The biological width seems to be an important factor in implant dentistry. What is your opinion on this subject?

A: I don't believe that "biological width" is a factor in implant dentistry. Dr. Dennis Tarnow, who is the greatest proponent of this concept, observed bone loss around two-stage Branemark^® implants and surmised that several millimeters of bone loss was inevitable below the junction of the implant and the abutment. This theory excluded the more likely scenario that stress under the wider 4mmD neck of the 3.7mmD Branemark implant was a source of stress concentration that resulted in bone loss. This is what Branemark's 1977 textbook concluded (Branemark P-I, Hansson BO, Adell R, et al. Osseointegrated Implants in the Treatment of the Edentulous Jaw. Experience from a 10-year Period. Stockholm, Sweden: Almqvust & Wiskell International, 1977:110).

Another possibility is that the countersinking needed to place this implant also contributed to the bone loss. With the countersink drill separate from the final sizing drill, two possibilities exist. One is that, during seating, the implant bottoms out on the base of the countersink, rather than at the bottom of the socket. This could compress the base of the countersink, leading to bone loss. Another is that the implant bottoms out in the socket, leaving a space between the neck of the implant and the base of the countersink. This could also contribute to bone loss. Today, Paragon makes length-specific drills with built-in countersinks for its external hex Taper-Lock implants. This drill design helps ensure that the implant bottoms in the socket and on the countersink at the same time.

Another possibility for the bone loss associated with the Branemark implant is the imprecise fit between the implants and abutments (Dellow AG, Driessen CH, Nel HJC: Int J Prosthodont 1997;10:216-221). This has resulted in microbial leakage through the implant-abutment interface with subsequent bacterial colonization of internal surfaces of the implants (Persson LG et al., Clin Oral Impl Res 1996;7:90-95; Quirynen M et al., Clin Oral Impl Res 1994;5:239-244; Koka S et al., J Prosthet Dent 1993;70:141-144). It also allows rotational wobble between mated Branemark implants and abutments. Binon, for example, documented 6.7 degrees of abutment rotation with the Branemark System (Binon PP, Int J Prosthodont 1995;8(2):162-178). Lateral forces will cause tipping with the abutment joint cyclically opening and closing, causing percolation of bacteria from the junction. This undoubtedly would contribute to bone moving away from this junction.

THAT IS NOT TO SAY THAT ALL TWO-PIECE IMPLANT SYSTEMS HAVE THESE SAME LIMITATIONS. Paragon's friction-fit abutments and internal hex with lead-in bevel eliminate all tipping and rotational movements (Binon PP, Postgraduate Dent1996;3(1):3-13). The "Biological Width" theory is thus most likely based on a false premise from observations made on the Branemark System. Bone loss is inevitable if the ridge is thin, and is of little consequence if it is only a few millimeters in height. If it were the junction between mating parts that was causing the bone loss, why does Staumann's one-stage ITI® implant that has the supragingival junction still experience bone loss?

Some have suggested that a two-stage implant with a polished collar would provide better tissue health if the collar were left above the tissue. However, this would position the threads of the implant at the crest of the ridge. Exposed threads can't be a good thing, especially in an HA- or TPS-coated implant. Soft tissue health certainly has been demonstrated with smooth titanium healing collars and abutments.

I believe that, regardless of whether a two-piece implant is selected for a two-stage procedure or to position the margin as far subgingival as possible for esthetics, the top of the implant should be placed level with the crest of the ridge. Furthermore, the implant's surfaces should be designed with a 1mm smooth machined (not polished) neck to accommodate for the 1 mm of bone loss that most likely will occur just from the surgical insult to the bone. Below this relatively smooth neck region, a medium-rough surface should be placed to retard bone recession. If one wants a rougher coated surface on the implant, it should be separated from the 1 mm smooth neck by a 2 mm, medium-rough blasted zone. Paragon offers such a design, which is called the Dual Transition™ Selective Surface™.

When a one-stage procedure is desired, the implant should be designed to accomplish this with a 2-3 mm long neck that projects above the endosseous portion of the implant, as in the ITI, AdVent™ and SwissPlus™ implants. In the maxillary anterior esthetic zone, the use of a two-stage implant in conjunction with a healing collar for a one-stage surgical protocol is acceptable. It is even advisable to do so if the tissue is less than 3mm thick. A secure, friction-fit internal connection (Tapered Screw-Vent) would eliminate concerns about microleakage caused by micromovements. Steri-Oss' Replace Select™ implant, which claims to be usable as a one- or two-stage implant, requires leaving the implant body extending 2 mm above the crest of the ridge, which brings the rough coating and threads to the crest of the bone where they will be easily exposed to the soft tissue with a minimal amount of bone recession. Steri-Oss' ads show this implant used one-stage, but with a healing collar attached to maintain the opening through the soft tissue. A true one-stage implant should be able to accomplish this without the need to purchase extra parts.

Q: I was once an big user of Core-Vent/Paragon products, but dropped away during the Dentsply era. I am extremely interested in your new product line after reading a copy of your new AdVent™ and Screw-Vent® Implant Systems catalog. How is the new Paragon System selling here in Canada?

A: Many former Dentsply customers are now Paragon customers, due to the superior technology and precision engineering of the system. What is it going to take to convince you to start using the best implant system in the world? If you are only willing to accept external hex implants, then check out the advantages our Taper-Lock™ at: ../Brochures/Ext_Hex_Lock/cover.html

In the U.S., this implant lists for $125, compared to $248 for Steri-Oss and $292 for Branemark. The Taper-Lock's preparable straight abutment is now only $55. If you want implant dentistry to be more profitable and easier for your referring dentists, simply attach the abutment for them! If you have to buy the abutments, maybe the cost would be more important to you than it apparently is now. Because of the friction-fit connection created by our tapered external hex, the Taper-Lock comes with a 5-year guarantee of no loose screws under cemented bridges. This is a significant factor, if you are going to attach the abutment.

Taper-Lock also features triple lead threads that make seating three-times faster and with 12% less torque! You have probably switched from Steri-Oss' Replace® to Replace Select®, because Nobel Biocare and Steri-Oss are finally going to give you "what every dentist wants ... an internal connection," as their journal advertisements state. The underlying implication to their ad is that, for the time you have been using the Replace external hex implant, they have been giving you what you don't want...an external hex implant! Paragon is vigorously pursuing its legal rights to stop Nobelbiocare/Steri-Oss from selling the internal connection and we believe that we will be successful within this year.

For your dentists who want the ITI® system, our SwissPlus™ blows it away in both surgical and prosthetic advantages, while selling for about 60% less than the ITI. Review the technological advantages of the SwissPlus at: ../marat/octaplusnew.htm

If you want a better one-stage implant, the AdVent™ is your answer. SteriOss doesn't even have a true one-stage implant. They tell you to add a healing collar to their Replace Select implant. Read about the technological advantages of the AdVent system and a view a case study at:../TechnologyPages/finalpages/AdventIntro.htm

If you want a tapered two-stage implant, then our new Tapered Screw-Vent® is the ultimate choice. It offers the option of expansion/compression in soft bone, because it is inserted into a socket prepared with an undersized straight drill. For dense bone, straight Step Drills ensure thread engagement by the tapered apex. For more information about the technological advantages of the Tapered Screw-Vent and to view a single tooth case inserted by Dr. Louis Clarizio, visit our website at: ../TechnologyPages/finalpages/Screwventinro.htm

Dr. Clarizio did place some Replace Select implants that Nobelbiocare/Steri-Oss gave him. However, he has now come back completely to Paragon, because our many product advantages help him make far more money in his practice than any company could give him in products or honorariums.

If you want a direct comparison between the features (advantages) of the Tapered Screw-Vent to the Steri-Oss Replace Select implant, this is provided at: ../company/DrNiznickOnsec4.htm#sterioss

Q: Does anybody know about the Paragon Implant System? Is it good?

A: Paragon Implant Company employs approximately 250 people, maintains corporate offices in the U.S., Canada, Germany and Israel, and has distributors in 30 other countries. All of Paragon’s products are manufactured by its affiliate, Core-Vent Bio-Engineering. For more detailed information on Paragon’s products, visit our award-winning website ../index.html. Paragon has led the industry not only in innovative implant product, but also in using web technology and interactive computer programs to provide state-of-the-art education and customer service. While online, be sure to order Paragon’s free CD-ROM that contains an implant education program with over 800 computer-animated slides. It also includes an interactive treatment planning, ordering and inventory control program designed to facilitate communication between members of the implant team. To answer your question, however, I will briefly outline the developmental history of the Core-Vent/Paragon product line.

EARLY YEARS

Core-Vent Corporation was started in 1982 to market the two-piece, hollow-basket, Core-Vent® implant. The original design featured a Hex-Hole™; that accepted a variety of cemented posts. Due to its reasonable price, which was substantially lower than the Branemark® System at the time, and easily accessible education programs, the Core-Vent implant became the most widely used root-form implant in the world by 1986. Other systems were also first introduced around that time. The IMZ® System, for example, which is still marketed, but essentially defunct. The Calcitek® System, as another example, coated the implant to its top, and the abutment fit against it. Unfortunately, the resulting soft tissue problems contributed to giving HA a bad reputation. A third example is the Steri-Oss® System, which was first introduced as the Denar® System. The initial implant design was a screw that accepted cemented abutments, and featured a 4mm long smooth neck.

SPECTRA-SYSTEM® EVOLUTION PERIOD: 1986-1990

In 1986, Core-Vent broke the tradition of one design for each implant company by introducing a second design targeted at the Branemark business. This was the Screw-Vent® implant, which featured the same thread design (0.6 mm pitch) and made from the same material (weak Grade 1 commercially pure titanium). In time, that choice of metal proved not to be a good idea. The Screw-Vent did bring two innovations to the industry. The first was its self-tapping design: vertical cutting groove and threads to the apex. The second was a unique internal Hex-Thread® connection (US Patent # 4,960,381). Core-Vent Corporation added three other implant designs over the next three years. The Micro-Vent® (1987) was the first small-diameter (3.25mmD), root-form implant and the first HA-coated screw implant. This implant featured a unique design (ledges on body with apical threads) and a unique surgical protocol (push-in for ease of insertion, with final thread-in for stability). The Swede-Vent® implant (1987) was the first real Branemark clone. Finally, the Bio-Vent® HA-coated cylinder featured vertical grooves and apical vents to alleviate hydraulic resistance to full seating.

In 1990, to make some sense of this array of hardware, Core-Vent introduced the Spectra-System concept of designating different implants for different locations of the jaw. Soon afterwards, the V.A. clinical study that evaluated 2800 of these implants at 32 U.S. government Veterans Affairs Hospitals began. The V.A. study primarily proved that HA-coated implants achieved and maintained significantly higher success than acid-etched implants, and overcame limitations of soft bone, surgeon's inexperience and even smoking. Approximately 700 Micro-Vents were included in the study, of which 97.5% achieved 3-5 year success. The crystallinity of the HA used in this study was not as low as the HA applied to the implants in the late 1980's, and not as high as the HA used by Paragon today. Review the V.A, study results at:

../research/studies/study2_pt01-1.html and ../research/studies/study2_pt01-1.html

DENTSPLY PERIOD: 1991-1997

For the 6-year period from April 1, 1991, to May 31, 1997, Dentsply International distributed the products still manufactured by Core-Vent Bio-Engineering. In 1994, the external hex of Core-Vent’s Swede-Vent® implant was redesigned to incorporate a patented 1.5-degree taper (U.S. Pat. #5,433,606). The name was changed to Swede-Vent TL (Taper-Lock), and provided a very stable friction-fit connection when used with Swede-Vent abutments. The Swede-Vent TL was still only available in 4.0mmD with a Branemark®-compatible platform (4.1mmD/0.7mm-high hex).

In 1996, the Screw-Vent’s strength was improved by increasing the neck diameter from 3.5mmD to 3.7mmD, which necessitated design of length-specific drills with built-in countersinks. Maximum strength was further ensured by eliminating the use of Grade 4 CP Ti in favor of titanium alloy, which had been offered as an option since 1990. The diameter options of the Screw-Vent were increased to include a 3.3mmD (still with a 3.7mmD neck) and a 4.7mmD body. This Screw-Vent line was further expanded during this time to include Healing Collar Packaging for one-stage surgery. Together, these Screw-Vent Implants were called the Paragon System. The word "paragon" means "the standard by which all others are judged."

CORE-VENT CHANGES ITS NAME TO PARAGON: 1997

When Core-Vent regained distribution of its product lines in 1997, the company changed its name to Paragon Implant Company. This may have led to some confusion between the name of the company and the name given to the one-stage Screw-Vent implants packaged with healing collars. From April 1997 through the end of 1999, Core-Vent/Paragon introduced several new product changes. Among these, the Micro-Vent was tapered and reintroduced as the Micro-Vent2® and a 5.7mmD implant was added to this line. Paragon also introduced the Complete® Implant, a one-stage, one-piece implant with a platform compatible with the Branemark Standard Abutment. Its 3mmL neck extension could be used as the abutment for screw-retained restorations, or adapters (abutments) could be added similar to 2-piece implants.

After 1997, the Swede-Vent TL implant line was expanded to include 3.3mmD and 4.7mmD options, all with the same platform as the 3.7mmD implant. In 1999, Paragon's triple lead threads were also added for three-times faster insertion and 12% less torque than single-thread implants. The material was also changed to work-hardened Grade 4 commercially pure titanium that withstood 421 lbs of compressive load at 30 degrees and 22.1 in-lbs of torque. The increased strength of its hex, coupled with Paragon’s Selective Surface® process of leaving HA-coated or SBM-blasted implants with an uncoated, machined apical end (US. Pat #5,571,017), made self-tapping insertion possible in all qualities of bone. The fixture mount that comes preattached to the implant was also redesigned in 1999 to serve as a transfer and temporary abutment.

By 1999, the advantages of the Complete Implant and the Screw-Vent implant with Healing Collar packaging, both one-stage implants, were combined into the AdVent, which replaced these designs. The AdVent Implant offers several significant improvements:

1. The platform changed to a 3.0mmD internal hex with greater prosthetic versatility. It can accept a ZAAG Attachment (Zest Co.) for overdenture retention, and also accepts a full range of prosthetic abutments compatible with Paragon’s two-stage internal hex implants.

2. The body was tapered. In soft bone, the socket is prepared with straight drills for compression of the bone or expansion of narrow ridges. In dense bone, step drills allow self-tapping insertion of the implant.

3. The threads changed from a single-thread design to triple lead threads that reduce insertion time.

4. The Advent is packaged with a 2mmL Implant Extender that provides greater versatility in projecting the implant through the soft tissue for one-stage healing.

PARAGON IMPLANT COMPANY --- 2000

With the start of the 21st century, Paragon introduced the Tapered Screw-Vent®, which adopted the body design and surgical protocol of the AdVent implant and the Dual Transition® Selective Surface™ of the Micro-Vent2™ implant. The Tapered Screw-Vent is packaged for two-stage insertion with color-coded fixture mounts designed for use as transfers. This implant is destined to replace the tapered Micro-Vent2 and the standard Screw-Vent, as it combines the best features of both with the added advantages of triple lead threads. It will undoubtedly also replace the Bio-Vent® cylinder implant, because it is as easy to insert, provides added initial stability and is packaged with a Fixture Mount/Transfer that facilitates stage-one impressions. As dental professionals start to load implants earlier, and as more implants are placed immediately in extraction sockets, the design advantages of the Tapered Screw-Vent compared to the straight, non-threaded Bio-Vent become even more obvious.

Paragon Implants have been classified into three categories on our "click-to-chart" Interactive Case Planning and Product Selection Guide available free on Paragon’s CD-ROM:

Implants 2000 - Paragon's Premium Line of Implants consists of the Tapered Screw-Vent and AdVent implants.

Spectra-System: This line consists of the old Screw-Vent, tapered Micro-Vent2 and Bio-Vent implants.

1. Implants 2000: Paragon's Premium Line of Implants consists of the Tapered Screw-Vent and AdVent implants.

2. Spectra-System: This line consists of the old Screw-Vent, tapered Micro-Vent2 and Bio-Vent implants.

3. Economy Implants with industry-compatible platforms:

a. SwissPlus: With Straumann’s introduction of an internal octagon connection in the ITI® implant, Paragon did two things. First, Paragon sued Straumann for patent infringement. Second, Paragon cloned the ITI implant and added a number of advantages, including self-tapping threads, preparable abutments that cover the implant’s shoulder, and a fixture mount that is also the transfer and preparable final abutment.

b. Taper-Lock: This system features Paragon’s patented tapered external hex (and friction-fit abutments), triple lead threads for three-times faster insertion and a fixture mount that also serves as a transfer and temporary abutment. Taper-Lock implants are now priced at $125 for the SBM-surface and $135 for the HA surface.

IN CONCLUSION

In reference to the comment that Paragon implants are very good, as are 3 to 4 others, one needs to define what features are important in a system, and then look for the system that offers the greatest number of these advantages. In evolving the AdVent and Tapered Screw-Vent into what is, in my opinion, the paragon of implant systems, here is what I considered important:

1. Surgical Simplicity

A. Protocol for Soft and Dense Bone

i. The tapered implant design allows the tip of the implant to initiate insertion into an undersized socket, then expands soft bone to maximize initial stability.

ii. Double-cutting step drills reduce the number of drills needed to prepare the osteotomy. Since they are only used as final sizing drills in dense bone, they can be slightly wider (3.4 mmD vs. 3.2 mmD, 4.4 mmD vs. 4.2 mmD) than the straight drills. This reduces the insertion torque needed for self-tapping in dense bone.

B. Triple lead threads make insertion three-times faster. This neutralizes the "ease of insertion" advantage of a cylinder implant. It also provides the initial stability and increased surface area needed today for one-stage implants, stage-one transfer impressions and early/immediate loading.

C. Multipurpose Packaging

i. The AdVent is packaged with an implant extender and cover screw.

ii. The Tapered Screw-Vent and Paragon's other two-stage implants (excluding Bio-Vent) are packaged with fixture mounts that also serve as transfers and temporary abutments. Paragon's SwissPlus features a fixture mount that is also the final preparable abutment.

D. Adequate strength, even in small diameters. At 30 degrees compression, the new 3.7mmD Tapered Screw-Vent and AdVent implants can withstand 378lbs and 415lbs of force, respectively.

E. Surfaces with demonstrated higher percentage of bone attachment and removal torque than machined or acid-etched surfaces. Blasted and HA-coated surfaces outperform the very rough TPS surfaces, and all of these achieve greater bone contact than acid-etched and machined surfaces. TPS and beaded surfaces have a potential for soft tissue complications if they become exposed, due to their interconnecting pores.

F. Stability of the implant/abutment connection. Screw loosening has been demonstrated to relate to the rotational wobble between mating parts. Paragon's patented internal hex reduced rotational wobble from 4-6 degrees down to 1.4 degrees (Binon) and Paragon's friction-fit abutments totally eliminate rotation and tipping movements that cause screw loosening.

G. Prosthetic Versatility and Simplicity. Fewer platforms means fewer parts. Color coding and interactive product selection guides reduce or eliminate confusion in product selection.

H. Cost and Value Equation. The least expensive implant to buy may cost more chair time for insertion and management of complications. On the other hand, paying a high price for a product does not assure its quality or its efficacy. One needs to be discerning and not influenced by "opinion leaders" who probably don't pay for their implants, and often get paid just for advocating the use of a particular system. The AdVent is a medium-priced implant with many patented features, and the top of the implant can be used as the abutment in screw-retained cases. It is packaged with an implant extender that eliminates the need to purchase healing collars of varying heights to maintain the tissue opening. Fixture mounts on two-stage implants that are usable as the transfer and even the abutment save additional costs. The most costly product is one that fails to integrate. Clinicians must look for features in the surgical protocol and surface options that will overcome soft bone limitations and inexperience.

While the comment that Paragon is very good, as are 3 to 4 others, not all implants and implant companies are created equal. It takes the discerning dentist to differentiate between competing product claims... and a discerning manufacturer to try to differentiate its product through features and benefits rather than through its marketing and hired opinion leaders.

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