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Please use this place to share your experiences or just ask a question about the Bioclear Matrix System by Dr. David Clark. Click here to learn how to post, comment or view the blog FAQs.

Thursday, June 23, 2011

10 most common reasons for post-operative sensitivity with composite restorations: Why it happens and solutions to fix it

  1. Reason 1: Poor dentin engagement by bonding agent. Solution A: Apply two or more coats of your bonding agent, air thinning and curing each layer individually. Solution B: Switch to a one bottle, self etch resin like 3M’s new Easy Bond that still allows you to use a rinse etch step to maximize the enamel bond. SE (Self Etch) resins are the most foolproof way to eliminate post operative sensitivity but you must also read and understand Reason #6. (see below)

  2. Reason 2: Not curing the bonding agent over the dentin before placing flowable composite and paste for injection molding. Solution C: ALWAYS air thin and then light cure the bonding agent over the dentin before re-wetting the cavity with a second application of bonding agent (used as a simple wetting agent) before injecting the flowable followed by the paste. Enamel doesn’t need to have the bonding resin cured first, but dentin does. If you are unfamiliar with the Injection Molded Technique please visit the Bioclear website.

  3. Reason 3: Boxy prep with bad C Factor, especially small, shallow composite restorations cut with retentive features. It is mind boggling that a conservative class I composite can cause terrible post-operative pain and on the same patient a deep restorations has no post-operative sensitivity. The problem is C factor. Please contact me for a full description of modern cavity preparations. Most schools, journals and opinion leaders are married to a cavity preparation that is a modified amalgam or silicate preparation. Those 100 year old retentive preparations do not serve modern composites, the tooth, or the clinician. Cutting and restoring a non-retentive class II composite is at once liberating and frightening. Thousands of doctors are now preparing non retentive class II’s with great success, but we remain a small minority Solution D: Cut a non-retentive prep as I have described in other documents and videos available online.

  4. Reason 4: Dealing with retreatment of old boxy amalgam and composite preps. Solution E: You can always play it safe and cover all of the dentin with glass ionomer before placing the composite. Solution F: Use strategic and incremental layering of flowable to rebuild the dentin, then place the paste composite “helmet” with cusps built and cured individually to eliminate cross tooth shrinkage and then injection mold the interproximals. For severely broken down molars I would prefer to do a nice PFM. Most composite margins on cementum will microleak. Period.

  5. Reason 5: Using flowable as a liner straight over the dentin without a bonding agent. This will cause bizarre and strong post-operative pain. Solution F: Always use a bonding agent which has been air thinned and light cured, or a glass ionomer base underneath flowable composite. (There are some self etching flowables that have just been introduced, check back with me in 2 years to see if they are worth trying)

  6. Reason 6: Acid etching (rinse etching) the dentin before using any Self Etch bonding agent other than 3M Easy Bond. Examples: Self Etching adhesives like SE bond or Optibond FL. See solution B above

  7. Reason 7: Old, contaminated, or unshaken bonding resins. Solution G and H: Get a new bottle and or check the expiration, and makes sure to shake the bottle each time you dispense a one bottle resin such as Optibond Solo Plus. (The primer and bonding agents can separate like oil and water) If in doubt email me and we will send advice for your favorite bonding resin or a complimentary sample of a bonding resin that is more foolproof.

  8. Reason 8: Not following orders. Solutions I, J, and K: Make sure and agitate the bonding resin on the tooth for the time prescribed if the manufacturer calls for that. Air thinning the resin also drives off the solvents if you are using a one bottle bonding agent. Read the directions.

  9. Reason 9: Inadvertent and unknowing pulp horn exposure without subsequent hemostasis. Mechanical exposure of a pulp horn is common, especially in young patients and when not using enough magnification. If pulp horn bleeding or weeping is present, placing a bonding agent will nearly always kill the pulp, even on microscopic exposures. Solution L: Use more magnification to avoid and also to identify tiny exposures. Stop the bleeding or oozing with Hemodent, sodium hypochlorite, even sterile water or saline and mild pressure. Once you think that things are dry, count to 20 to make sure it stays absolutely dry. MTA or Biodentine by Septodont show promise as direct pulp capping agents but indirect pulp caps are proven better than direct exposures in outcome studies. Composite or glass ionomer will only work as a pulp capping agent when there is absolute hemostasis. Carious exposures are very high risk to kill the pulp, although the makers of Biodentine think they can predictably treat carious exposures. Check with me in 5 years on that one, and in the meantime stick with indirect pulp caps where you cut a clean margin but leave a little “beret” of carious dentin in the middle of the cavity prep over the pulp. The pre-dentin and pulp will subsequently begin to heal the dentin. Over time the body will harden, disinfect, and dry out that little spot of soggy dentin lying next to a pulp horn. See the Journal of Endodontics 9/2010

  10. Reason 10: Occlusal trauma. Solution M: Understand that composites absorb at least 1% of their volume in water after they are placed. In our new preparations, there is a larger cavosurface area covered with composite. I recommend leaving all new composites slightly out of occlusion because in 24 hours the composite will swell. Unless the restoration is in hypo-occlusion when you dismiss the patient, it will likely be in hyper-occlusion within 24 hours.

Monday, January 4, 2010

"...Bioclear is proof of an intelligent mind and professional dedication"

Dear Dr. Clark,

You will probably not remember me but we met at ESMD in Amsterdam, september 2008. I was in your masterclass there and you introduced us to the Bioclear system. Thanks for these inspiring hours and also for the samples that were sent later on! As my practice is limited to endodontics, I don't have the kind of cases to do saucer shaped class II preps, but now and then I have to do a 'pre-endodontic buildup'. That's where the Bioclear matrices come in handy.

Below are images from a case where I used the 'average curved molar' matrix to restore a distal cavity (Fuji II LC was used for that) on a necrotic 14 before starting endodontic procedure. The matrix is great since it is convex in all directions and fits intimately with the remaining tooth structure. Together with the interproximators it results in very natural and physiological interdental contacts, minimal surplus filling material, and less finishing work.

The development of Bioclear is proof of an intelligent mind and professional dedication.

Congrats with this achievement,

Best regards, Maarten Meire, DDS, MSc Belgium

Thursday, July 9, 2009

Is this true or are the matrices in the porcelain kit different from the matrices in the other composite kits?

The marketing material states that the matrices in the porcelain kit are ultra-thin. When I asked my CRD rep to order the porcelain kit she told me the only difference between the porcelain kit and the other kits is the inclusion of porcelain etch and silane. Is this true or are the matrices in the porcelain kit different from the matrices in the other composite kits?

- Dr. Stephen Tsotsos


No the porcelain kit also has a roll of ultra-thin mylar that is 5 mil versus 20 mil which means it's only about 19 microns instead of 75 microns thick. That is an addition to regular thickness Bioclear Matrices that are also in anterior and posterior kits. It also has some neat opaquers.

Thursday, June 25, 2009

Do Dental Composites Always Shrink Toward the Light?


Watched your video of restoring a biscuspid, very interesting system. Did you bulk cure the restoration, and if so did you use the curing light on each side in an attempt to pull the material outward towards the light to compensate for shrinkage? I believe studies have shown that composite does not shrink towards the light, it shrinks towards the strongest bond in the prep boundaries also influenced by the C factor.

Do Dental Composites Always Shrink Toward the Light?: J Dent Res 77(66) June 1998



Dear David

You are correct, we do not have any evidence that the composite shrinks toward the light. There is, however, some consensus that the composite that cures first has the first foothold and that it may have an advantage. Because the gingival margin is always the weak link, It doesn't hurt to do all that we can to help it. C factor, the amount of enamel rods and the angle of engagement (saucer versus GV Black walls) are probably more important to determine which margin experiences the most "suck back".

The C factor of the Clark Class II is so low that we can fill in one increment. I am currently doing an article on these topics at the request of 3M which I will send the final draft of if you promise NOT TO DISSEMINATE until it publishes. My 2 hour lecture on the topic will be available shortly on dentaledu.tv (Just taped it this weekend). It gives a very thorough discussion of C-factor and other topics that you have interest in. I am so happy that you have such a good feel for these issues, not too many dentists take the time. Good for you.

Warm regards,


Thanks for the response. I do like playing devil's advocate on stuff like this. I didn't watch all of the videos so I don't know what you do with say an MOD. The case shown is saucer but in restorations that extend well into the central fossa areas it might be a higher C factor. Also when you create the flare for the saucer the ends of polymerization are farther apart so potentially more shrinkage between ends. I remember someone years ago was putting composite over flow and curing together. I cure the flow first so it gets a maximum foothold before the filled resin.

I promise not to share any of the article with anyone until published and would be glad to read it and give you my feedback. There is a huge need for the average general dentist to improve direct composites and I'm glad dentists like you are thinking about it and making it better.



For all medium, large, and amalgam retreatment cases I suggest rebuilding the occlusal separately, then prepping the interproximal and restoring each saucer independently so the C factor remains favorable. As far as a larger size impacting shrinkage, everything that we have seen shows that a feather edge on a flattened restoration (assuming enamel margins) will not have any problems. My theory is that a feather edge over a flat surface area encourages the composite to dissipate the stress and shrinkage by simply shrinking toward the tooth instead of toward the center of the composite mass and since there are no opposing walls in the prep, the tooth is too strong to accept any stress,

So in the end, no white lines no micro fracturing,
Think about placing a large thin composite on the facial of an upper incisor to cover decalcification or stain. The margins look perfect year after year.

Dentin is another story.


Is the Bioclear light a pulse light?

Is the bioclear light a pulse light. I don't want it getting too hot is the reason I ask. I couldn't find any info on it to say one way or another and I know that 5 sec LED lights can heat up without the pulse.

Thank you.



Dear Ryan,

You have a very good question.

While I did research and lecturing for CRA I learned an awful lot about curing lights.
  1. Pulsed and ramped curing have never been shown to have any clinical significance in their attempt to reduce stress of curing.

  2. There is stress from asymmetrical curing, that's why the bioclear method encourages simultaneous curing from buccal and lingual with 2 lights.

  3. The Bioclear /Vector light does not get hot at the tip after 5 seconds. HOWEVER all rapid cure lights have a tremendous photon transfer to the tooth, that's why hey cure so fast. All of these rapid cure lights can create heat in the tooth because so many photons are hitting the tooth at once. The recommendation that we gave at the CRA lectures was to begin to air cool or air suction after 3 or 4 seconds to keep the tooth cool We have several thousand doctors who are doing the Bioclear method and post operative sensitivity is very low. If we were heating the pulp xcessively, we would be seeing problems, and we are not.
Please let me how how else I can help,

Warm regards,

Tuesday, June 2, 2009

How do I get the resin in and pack it if the matrix is over the buccal and lingual aspects of the prep?

I have had quite good results so far from my trial anterior and diastema closure kits. One problem I have experienced is that once in place, the matrix blocks off the access for resin placement. I have bent it out of the way, but this sometimes runs the risk of disturbing the soft tissue /gingival seal or distorts the matrix. Any advice as to how to get the resin in and pack it if the matrix is over the buccal and lingual aspects of the prep?

Dr. Lisa Chong
3006 Bloor St. West
Toronto, ON M8X 1C2


If you are having access problems you can:

  1. Place the paste composite indirectly by syringing it on the facial and or palatal, and then "patty cake" it into the interproximal with a flat composite instrument (I like our Bioclear/Hartzell titanium coated B6-7T "Composite Placing Instrument") and then you can bend the matrix less. I am doing that technique more and more. Place a small dollop of flowable first to eliminate voids. The flowable canula is small enough that you should be able to insert it directly under the teased matrix without excessive distortion of the matrix. The larger paste syringe creates a lot more matrix movement.

  2. Cut back a small area of the flange that is blocking your access.

  3. Have the assistant tease the matrix away with an explorer while you are placing material

  4. Change mirror position

  5. Use the Universal 10 mm matrices (Flat Universal 10 or Curved Universal 10). These are more "open matrices" with good cervical shapes.

I use all of the above, depending on the case.

Hope that helps,

Friday, May 22, 2009

Which materials (matrix and interproximator) would be suitable for an in-the-mouth repair?

Hi, Dr Clark,

I have been, for some time, what I consider to be a practitioner and advocate of MID but your article raised my consciousness about aspects of our contemporary approach. The use of microscopes over loupes is inarguably an advantage. But the paradigm shift of class 2 preparation design is most thought provoking. I plan to begin using the Bioclear matrices with the interproximators.

I saw a patient today who had a 1mm diastema between the upper first and second molars.This was produced by a relatively small mesial marginal ridge fracture of the porcelain on a porcelain-fused to-metal crown on the second molar. I was interested in attempting an in-the-mouth repair using your system. Which materials (matrix and interproximator) would be suitable for this type of repair? Is there a description of the technique on the Bioclear website? Do you think these repairs are durable?

Thanks for your help.
Joseph Ritz, DMD
Wayne, PA


Dear Joseph,

I have repaired several of these marginal ridge fractures and most have done well. (Including one on my wife!). The website or your DVD have a step by step in the "yellow" or porcelain section.


Remember that many of these fractures may have been precipitated by marginal ridges that were either just too tall or were too "sharp" and were unsupported with a bit of a point contact. This stems from an under-contoured emergence profile in some cases, or a poor contact on the adjacent tooth that probably could have been smoothed or contoured at the time the crown was done. Make sure and address those to increase your chance of success.

Let me know how it goes and take some pictures if you can. Call technical support also with any questions.