Frequently Asked Question
This section of our website is devoted to the questions that our customers and associates have asked or been asked over the years. If you have questions, submit them to info@rtd.fr
Answer:
Several Ways:
- The Elastic Modulus (rigidity) of fiber posts is about the same as dentin (~20GPa). Titanium is 5 times as rigid, Stainless Steel and Ceramic / Zirconium posts are 10 times more rigid. This mechanical mis-match predisposes to damage to the tooth including root fracture.
- Most fiber posts (excluding Carbon fiber) are tooth colored or translucent, therefore aesthetic
- Fiber posts cannot create a galvanic or corrosion potential, as Stainless Steel can
- Fiber posts are removed quickly by drilling through them, rather than by removing surrounding tooth structure. It is virtually impossible to safely remove a ceramic posts, or even trim its length.
Answer:
Yes. We have a much longer rack record with the total-etch / adhesive systems, but the short term clinical results with the self-etching cements is promising.
Answer:
Actually, they’re stronger. Our fiber posts test out in a range of 1400 - 1800 MPa in Tensile strength versus a value of 800 for stainless steel, 1000 for titanium.
Answer:
Because of the micro-mechanical machined surface of our posts, even glass ionomer and zinc cement will mechanically attach to the post. We once marketed a serrated post version, often used to attempt the increase in bond strength. However, because powder/liquid cements are soluble in oral fluids, we whole-heartedly recommend the use of 4th or 5th –generation adhesives (such as SEALBOND ULTIMA) with dual cured resin cements such as SEALBOND). We also recommend the use of dual-purpose resins, such as CORECEM, which can be used as the luting cement AND core build-up.
For dentists that are not comfortable with bonding, RTD offers the MACRO-LOCK ILLUSION post, with macro-mechanical features.
Answer:
The original COMPOSIPOST is composed of 64% Carbon fibers, which are black in color. The COMPOSIPOST is available in the original 2-stage taper and in 3 ISO gauge sizes. In contrast, the AESTHETI-PLUS and LIGHT-POST utilize a very high quality esthetic MINERAL fiber (62% and 60%, respectively), to provide esthetic tooth-colored or translucent post shades. The AESTHETI-PLUS and LIGHT-POST are available in the 2-stage, ISO and new Double-Taper designs.
The Mechanical Properties (including fatigue resistance) of the 3 styles are nearly identical, with the COMPOSIPOST exhibiting a higher Elastic Modulus at 0°-20° (120 GPa), compared to -50 GPa for the AESTHETI-PLUS and LIGHT-POST.
Answer:
The DT LIGHT-POST, MACRO-LOCK and 2-stage LIGHT-POST are radiopaque, per ISO standard #4049.
Answer:
All versions of LIGHT-POST, DT LIGHT-POST, MACRO-LOCK , AESTHETI-PLUS and FIBERCONE utilize quartz fibers.
Answer:
For some industrial uses, the difference might not be significant. It is RTD’s foremost priority to produce posts that demonstrate SPECIFIC and reproducible mechanical values for Elasticity, Tensile and Flexural Strength, Flexural Modulus, radiopacity, surface characteristics and, more recently, light conductivity. We have examined and tested all types of mineral and glass fibers from around the world for suitability to this end, and find that ONLY a particular grade of Quartz fibers deliver these unique requirements.
Most other manufacturers of fiber posts are resigned to use the cheapest type of glass fibers available, and the resultant post if of poor and/or variable quality.
It is our view that since the life-span and efficacy of your crown and bridge work often rests on the substructure dominated by the post, reproducible QUALITY should not be compromised for cost/price. We respect dentists who feel likewise about their own work!!!
Answer:
Authoritative academic researcher / authors have now published retrospective CLINICAL TESTING on RTD fiber posts 7 – 11 years in duration. This includes both Carbon and Quartz fiber posts and the results are the same. There are a number of 2 – 4 year studies published
There are also 2 - 5 year published studies on the DT LIGHT-POST.
In the private sector, MILLIONS of RTD fiber posts have been placed in over 75 countries. Reported failures are minimal.
Answer:
We have dedicated a section of this website to this research. Click SCIENTIFIC REFERENCES.
Answer:
Fiber posts are alike in that they all have a low Modulus of Elasticity, they are bondable, most are aesthetic and are removable quickly, compared to metal and ceramic posts.
They differ in:
- The type, percentage, pre-treatment and quality of the fibers used.
- The matrix. We use a proprietary epoxy, most use Bis-GMA resin.
- Their manufacturing process.
- Radiopacity
- Shape (parallel versus tapered or pointed)
As a result:
- Ours have a Flexural Strength of 1600 MPa, some are as low as 579 - 900MPa.
- Ours have superior Fatigue Resistance and have a published clinical track record.
Answer:
We recommend dual cured resin-based cements and core-materials, or all-in-one resins for all of our posts. MACROLOCK can also be cemented with Glass Ionomer, if necessary.
Answer:
This will vary according to user, but dentists should not use the drills more than 15 times, if properly cared for. In the case of a post removal, a NEW drill should be used, and ONLY used once.
Answer:
The Elastic Modulus (or Young's Modulus) is a calculated measurement of the relative rigidity of the material. LOWER modulus indicates MORE flexibility, and it is inherent to the material, regardless of size or diameter.
Flexural Strength is measured in a 3-point bending test and quantifies at what load (under very specific standardized conditions) the material breaks. The Flexural Strength IS related to diameter; the larger the diameter, the higher the flexural strength.
The LOW Elastic Modulus of the fiber posts helps prevent root fracture. The higher the Flexural Strength of the post, the more durable the restoration will be.
Answer:
Yes. There is a plethora of research that challenges the wisdom of the use of stainless steel (nickel – CHROMIUM) in human tissue. By comparison, Titanium and Zirconium are relatively inert. Our fiber posts have been independently assayed for cyto-toxicity and has 510 (k) approval by the FDA in the USA. For specific test methodology (ISO 10933 series), click BIOCOMPATIBILITY
Answer:
The simple conceptual answer: hollow it out from the inside.
RTD offers TWO different removal drill kits; one for the DT LIGHT-POST and MACROLOCK posts, and the other for RTD’s original "2-STAGE" fiber posts; Composipost / C-POST, AESTHETI-PLUS AND LIGHT-POST.
The basic removal technique can be learned in this REMOVAL VIDEO. Always read the Instructions For Use inserts included with the removal kits
Answer:
Here are the dimensions and tapers for the three RTD post designs. The DT Light-Post has the best anatomical design of all prefabricated posts.
(Insert photos / drawings).
Answer:
Clinical experience is the best determinant. However, in general terms, here are suggested indications. These schematics indicate the most likely post size for each canal in the permanent dentition.
Insert photos of upper / lower photos with "dots"
Our posts and drills are color-coded to match their corresponding placement drills.
Answer:
No. Based on worldwide consumption of our fiber posts, the 0.5 and #1 smallest post sizes will be used 60% of the time, the #2 post 30% of the time, and the #3 post 10% of the time.
Answer:
Patent # 4,738,611 is held by Dr. Marc Reynaud. Patent # 5,328,372 is held by Dr. Marc Reynaud, Dr. Bernard Duret, Dr. Francois Duret and Pierre-luc Reynaud, all of Grenoble, France. Dr. Reynaud is retired and his son, Pierre-luc Reynaud now manages RTD. RTD also owns several other patents relating to low-modulus reconstruction materials.
Dr. Bernard Duret practices part-time, lectures and consults frequently with RTD.
Answer:
It isn’t necessary; it just gets in the way.
Most metal posts were designed in the 1940’s, - 1970’s, when amalgam was the core build-up of choice. Because amalgam is NOT adhesive, it relies on this type of MACRO-mechanical retention on the post, and (unfortunately) in the tooth, to keep it in place.
Our fiber posts are meticulously machined to provide the optimal porous (5 – 15 microns) surface for modern bonding agents, core composites and cements. This method provides a micro-mechanical attachment with bonding adhesives, resin cements, self-etching cements and Glass Ionomers. There are studies in the BIBLIOGRAPHY to support this proposition. The composite core material is also bonded to the tooth structure to help prevent rotation.
Not having a retention head facilitates a smaller inventory of posts sizes for you, AND allows for smaller, narrower core build-ups when necessary.
For dentists who are not quite comfortable in the bonding procedure, RTD offers the MACRO-LOCK fiber post, which features some retentive features.
Answer:
Although not officially recommended by RTD or its distributors, dentists are using our fiber posts for splinting mobile teeth.
Answer:
Slim to none, if done properly. The in vitro tests and clinical studies supporting our products include a wide variety (brands, chemistries and “generations) of adhesives and cements. In most of the failures seen (~2% clinically), the failure is at the cement-dentin interface, and NOT at the post-cement interface.
Bonding to interior dentin is like bonding to exterior dentin except harder to see and reach. Moisture control is always critical. A recent in vitro study (Simonetti, et al, 2007) shows that following the directions, the bond strength achieved by inexperienced operators was as good as the results achieved by the “experienced” and “expert” clinicians included in the study.
Some general guidelines:
- Rubber dam is always a good idea.
- Always be sure that the adhesive system you are using is proven to react properly with dual-cure and chemical-cure cements. Not all brands / formulas do this.
- Use a Micro-brush or Composibrush to apply liquid adhesive or cement to the bottom of the post space.
- Our fiber posts perform well if placed to a depth of ½ to 2/3 the length of the root…or a depth equivalent to the length of the natural or prosthetic crow. This will rarely exceed 12 mm.
- Since the low-modulus post is mechanically innocuous (neutral), fiber posts can be seated deeper , if necessary, to achieve good adaptation in the interior bonded area.
- If using a 2-bottle, 4th generation adhesive (such as ALL-BOND 2), do not waste time after placing the cement and placing the post.
- Using the same composition resin for the cement and core (eg CORECEM) can save time and materials, and reduce variables.
Answer:
Re-cement it or use another post. Clean and roughen the surface if re-bonding the “old” post, and re-drill the canal / post space.
If the post has broken in situ, consider it a blessing (a metal post would have likely fractured the root)
Answer:
Glass Ionomers yes: amalgam no.
Answer:
It is extremely rare. In clinical trials over 7 – 11 years’ observation, one case of post fracture has been reported. Our fiber posts can be removed in minutes, and a post fracture is always preferred to a ROOT FRACTURE.
Answer:
Light cure and dual-cure core composites such as BIS-CORE or LUMIGLASS are good.
Dual-purpose resins, such as RTD CORECEM can save time and materials and eliminate variables.
Composite resins, unlike Glass Ionomers, are virtually insoluble in oral fluids, if an open margin should develop.
Answer:
According to a large body of literature, 10 - 20% of endodontic treatments will require reentry, for reasons totally unrelated to the post/core. Our fiber posts can be non-traumatically removed in minutes if necessary, using the RTD Re-Access Kit.
Answer:
By design, it is virtually impossible for our fiber post to fracture a root in the mouth…the post itself is designed to fracture FIRST, by absorbing the stress. There is a multi-center clinical trial program that includes 8 dental universities in 4 countries, and was begun more than 15 years ago. Some of these have already been published; others will not be until the study protocol is complete. Of the 3477 cases in these trials, TWO root fractures has been reported with our fiber posts.
Researchers have been able to induce root fracture IN-VITRO, utilizing forces and/or conditions beyond those encountered clinically.
Answer:
There are a number of adhesives that Dentists have used to bond our posts. While most of the research on our fiber posts has been conducted using 4th generation total-etch-moist bonding systems, Other dual-cure systems can be utilized. As for light –cure adhesives, 5th generation can also be used, provided that the adhesive is shown to react properly with dual-cure and chemical-cure resin cements and core composites.
