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Who invented / patented fiber posts?

Patent # 4,738,611 (1988) is held by Dr. Marc Reynaud, founder of RTD. 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 manages RTD. RTD also owns several other patents relating to low-modulus reconstruction materials.

How are fiber posts different from prefabricated metal posts

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.

Are fiber posts as "strong" as metal posts?

Actually, some are stronger. RTD fiber posts test out in a range of 1600 - 2000 MPa (depending on the RTD brand) in Flexural strength; the tensile strength of RTD fiber posts is higher than Stainless Steel (1000MPa) or Titanium alloy (800MPa).

What's the difference between ELASTIC (Young's) modulus and FLEXURAL Strength, and which is more important?

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.

What are the differences and similarities between the AESTHETI-PLUS and LIGHT-POST and MACRO-LOCK?

The Aestheti-Plus and Light-Post / Macro-Lock utilize a very high quality esthetic MINERAL fiber (62% and 60%, respectively), to provide esthetic tooth-colored or translucent post shades.

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, Light-Post and Macro-Lock.

Are they radiopaque?

The DT Light-Post, Macro-Lock and 2-stage Light-Post are radiopaque, per ISO standard #4049. The utilization of the X-RO™fiber, beginning in 2009, makes the RTD quartz fiber posts roughly 50% MORE radiopaque that previous generations.

What kinds of fibers are used in RTD posts?

All versions of Light-Post, DT Light-Post, Macro-Lock , Aestheti-Plus and Fibercone utilize Quartz fibers.

Since 2009 these all utilize the exclusive X-RO fiber. See question #34 below for more information on X-RO.

Why would quartz fibers be better than glass fibers?

For some industrial uses, the difference might not be significant. It is RTD’s foremost priority to produce posts that demonstrate the optimal combination of specific and reproducible mechanical values for Elasticity, Tensile and Flexural Strength, Flexural Modulus, radiopacity, surface characteristics and, more recently, light conductivity. RTD 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 resulting post is 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.

Are your fiber posts bio-compatible compared to Titanium, Stainless Steel, or Zirconium?

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 cytotoxicity and are registered with the FDA in the USA.

What's their clinical track record?

Authoritative academic researcher / authors have now published retrospective clinical testing on RTD fiber posts of up to 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, and most often the failure is a de-cementation (~2%).

How many times can I safely use the drills?

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.

Do I have to use RTD drills with RTD posts?

The overwhelmingly positive clinical results over 25 years have been obtained using matching posts and drills. RTD has always provided drills that are exactly the same shape as their corresponding posts, but are 60 µ larger. This allows 30 µ of space circumferentially for the adhesive/cement, but does not allow potentially dangerous movement of the post in the apical section of the post space. In vitro bond strength tests also indicate that adhesion is improved with a smaller layer of cement.

Good clinical service depends on a good, close, tight apical fit of the post! Using the drills provided in the post system-any post system-promotes better results.

What's the difference between D.T. (Double Taper) Light-Post and Macro-Lock Posts or MatchpostTMversions? When would I prefer one instead of the other?

The dimensions and tapers for the three RTD post designs are available in the respective product brochures. The DT Light-Post has the most anatomical design of all prefabricated posts. Macro-Lock offers extra retention features for dentists that are not as comfortable with the meticulous bonding techniques and who prefer to use resin-reinforced Glass Ionomer cements.

DT Light-Post and Macro-Lock Post are “designer” post designs, with proprietary features and tapers. The “economy” Matchpost is a standard design; parallel with a tapered tip. Matchpost is not as radiopaque as the X-RO posts, and does not include the Illusion® color change technology.

How do I know which type or size post to select for each tooth?

Clinical experience is the best determinant.However, in general terms, there are suggested indications. The schematics indicate the most likely post size for each canal in the permanent dentition, and are included in Kits and Refill Packages Our fiber posts are color-coded to match their corresponding placement drills.

There is also a Size Selection Card included in certain Introductory and System Kits, which allows the clinician to determine the right size in a traditional (actual-size) radiograph.

Would I expect to use all 3 sizes in equal quantities?

No. Based on worldwide consumption of our fiber posts, smallest post sizes will be used most often; approximately TWICE as often as the larger sizes.

What does the clinician use when the root canal preparation leaves a wide, flared or ovoid space larger than the largest post in the range?

Traditionally, this would be when most clinicians would move to a custom cast post. This is no longer necessary. Published research indicates that the use of a master fiber post (such as DT Light-Post, Macro-Lock), accompanied by Accessory Posts (Fibercone®) provides perfect adaptation, esthetics, fracture resistance, etc., without increasing the risk of root fracture, which usually accompanies cast posts. There is also the Macro-Lock OVAL Post.

How do I cement the fiber posts?

RTD recommend dueal cured resin-based cements and core materials, or all-in-one resins for all of our posts. Macro-Lock Post can also be cemented with Resin-Modified Glass lonomer, if necessary or self-etching cement.

Can I use my own (powder / liquid) cement?

Because of the micro-mechanical machined surface of our posts, even glass ionomer and zinc cement will mechanically attach to the post.. However, because powder/liquid cements are soluble in oral fluids, we whole-heartedly recommend the use of 4th or 5th –generation adhesives (such as All-Bond ®2 or Sealbond Ultima™) with dual cured resin cements such as Sealbond). RTD also recommend the use of dual-purpose resins, such as Corecem, which can be used as the luting cement AND core build-up. The clinician is responsible to make sure that the adhesive/bonding agent of choice is compatible with the dual cure resin cement.

For dentists that are not comfortable with bonding, RTD offers the Macro-Lock Post Illusion with macro-mechanical features.

Can I use "self-etching" or "self-adhesive" cements to place RTD fiber posts?

We have a much longer track record with the total-etch / adhesive systems, but the short term clinical results with the newer generations of cements are promising.

Do RTD fiber posts allow light-curing of the cement to the end of the post?

Because there are so many variables involved to answer categorically and conclusively, the short answer is “no”.

RTD fiber posts are among the most light-transmissive in the world, but the main purpose of the light transmission and high translucency is aesthetics, and to allow curing of the cement in the coronal 3 mm of the post space, stabilizing the post prior to the next step.

Why don't all RTD fiber posts have some sort of retention / "head" like most metal posts?

RTD responds to market demands. 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. The composite core material is also bonded to the tooth structure to help prevent rotation.

For dentists who are not quite comfortable in the bonding procedure, RTD offers the Macro-Lock Post, which features some retentive features.

Can your fiber posts be bonded with any of the popular adhesive systems?

There are a number of adhesives that dentists have used to bond fiber posts. While most of the research on RTD 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 specific adhesive is confirmed to react properly with dual-cure and chemical-cure resin cements and core composites.

What are my chances of having a de-bonding failure?

It depends on the chemistry of the cementation media, and the clinical technique. 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 (students) was as good as the results achieved by the “experienced”and “expert”clinicians included in the study.

  • 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-brushR or ComposibrushTM 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 CORECEMTM) can save time and materials, and reduce variables.

What do I do if I have a de-bonding failure?

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). Remove the remains, preferably with an RTD re-access kit, according to the animated video

Can I use my Glass lonomers and amalgam for the core build-up?

Glass Ionomers yes, amalgam no.

What materials are available and most recommended for core build-ups with your posts?

Light cure and dual-cure core composites such as Bis-Core or Light-Core 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.

Can the post fracture (inside the restored tooth), and what do I do in that case?

It is extremely rare. In clinical trials of up to 11 years’ observation, a few cases 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. Remove the remains, preferably with an RTD re-access kit) according to the animated removal video.

What are my chances of having to re-access the canal / post?

According to a large body of literature, 10 - 20% of endodontic treatments will require reentry, for reasons totally unrelated to the post/core. Roughly 25% of those root canals will have a post involved. RTD fiber posts can be non-traumatically removed in minutes if necessary, using the RTD Re-access Kit.

The basic removal technique can be learned in this RTD’s animated video. Always read the Instructions For Use inserts included with the removal kits.

How do I remove the post if I have to?

The simple conceptual answer: hollow it out from the inside. RTD offers TWO different removal drill kits; one for the D.T. LIGHT-POST and MACRO-LOCK posts, and the other for RTD’s original “2-STAGE” fiber posts; Composipost / C-POST, Aestheti-Post, Aestheti-Plus, and LIGHT-POST. The basic removal technique can be learned in this RTD’s animated video. Always read the Instructions For Use inserts included with the removal kits. The Illusion technology makes it easier to identify the location and size of the post, if removal ever becomes necessary.

What makes your ILLUSION-type posts change color?

The simple conceptual answer: hollow it out from the inside. RTD offers TWO different removal drill kits; one for the D.T. LIGHT-POST and MACRO-LOCK posts, and the other for RTD’s original “2-STAGE” fiber posts; Composipost / C-POST, Aestheti-Post, Aestheti-Plus, and LIGHT-POST. The basic removal technique can be learned in this RTD’s animated video. Always read the Instructions For Use inserts included with the removal kits. The Illusion technology makes it easier to identify the location and size of the post, if removal ever becomes necessary.

What are my chances of having a root fracture with one of your fiber posts?

By design, it is virtually impossible for a fiber post to fracture a root in the mouth…the post itself is designed to fracture FIRST, by absorbing the stress. There are multiple published clinical trials-begun more than 20 years ago-reporting a very low rate of failure due to root fracture, and the cause of the root fractures is not related to the post itself. Root fractures are more often related to the obturation procedure. Nothing can repair a fractured root, however, clinical trials indicate that RTD fiber posts can help prevent these fractures.

Are there other benefits or advantages to placing an RTD fiber post in the compromised teeth?

In addition to the root - protective (stress distribution) aspects of the low modulus fiber post, there are other reasons to place a fiber post; especially in anterior teeth. In vitro studies from around the world indicate that placement of an RTD fiber post can reinforce the tooth, by raising the fracture resistance close to that of the uncut tooth, but without increasing the risk of catastrophic catastrophic failure.

What does X-RO mean and what is its implication?

X-RO is a marketing acronym for “ eXtra-RadiOpaque”. Over the last 5 years, RTD has been involved in the research and development of a specialized Quartz fiber, which contains more radiopacifiers. The new (patent-pending) fiber, used in the proven RTD manufacturing process, yields a post that is 50% more radiopaque than the prior generations of Macro-Lock Post or the D.T. Light-Post Illusion, and makes it the most radiopaque fiber post on the market. The X-RO fibers are coated with a proprietary silane coupling agent; specially formulated to optimize the bond between the X-RO fiber and the hybrid epoxy resin the RTD uses. The enhanced chemical bond between the fiber and the matrix plus the use of the new X-RO fiber improve the Flexural Strength of the post to 1800 -2000MPa (ISO Test # 14125 on raw material). That is about 20% stronger, and makes it the strongest fiber on the world market. Shear strength is also improved.

Quartz Splint

How is Quartz Splint different from my Ribbond, FibreKor, Connect, etc.?

Quartz Splint is made from a proprietary, pre-treated Quartz (high-silica) fiber which is stronger and more rigid that polyethylene (Ribbond) or industrial e-glass or s-glass (FibreKor, Connect, StickTech, etc.). Independent comparative testing (ISO Standard 4049) show this superiority. Quartz Splint is also pre-impregnated at the factory to ensure consistent wetness and quality from inch to inch, batch to batch.

What is the shelf-life of Quartz Splint?

Quartz Splint has a light-cure catalyst, and has a useful shelf-life of 2 years from date of manufacture, at room temperature (72F / 22C). Refrigeration extends shelf-life.

How is Quartz Splint presented?

Quartz Splint is offered in 4 varieties; Unidirectional, Woven, Mesh and Rope, for use in a multitude of clinical and laboratory uses.

Why do I notice loosening, or fraying of the ends of the Rope or Woven when I cut it?

The strength of the Quartz Splint lies in the fibers and their surface pretreatment with coupling agents. The fibers have a higher strength and elastic modulus (stiffness) and then some of the other fibers on the market, so they can unwind when they are cut. This phenomenon is aesthetic only and is not impair the product’s efficacy. To eliminate or minimize this, use very sharp scissors when cutting, and/or try this procedure using the Quartz Splint box and your curing light.