I’ll be honest I’d never heard of a sectional matrix until Zaid wrote his blog about them on June 9th 2009. I probably should have done but the knowledge must have just slipped though my fingers.
Well, the picture Zaid put up is here. Just look at it a beautiful rubber dam, lovely sharp contact point, excellent moisture control and contoured to the box beautifully. I look at that picture and I just want to grab some composite and get painting. You can really have fun with your aesthetics when you have that kind of control with your matrix.

Here is something I’ve realised: control= aesthetics. Control the environment and you then have the time to control your aesthetics.
Since the day I saw that picture I have been obsessed with gaining that kind of control and it has been a difficult journey. Your first thought is that no one can possibly work like that all the time, surely it takes too long, it’s too expensive, too fiddly and technically difficult. I also had to get hold of the kit, get better placing rubber dams, placing normal matrix’s and generally get better at placing composites to make this worthwhile. One of my rules is that I need to try and master all the basics before I pay out on expensive new kit or it won’t be worth the while. Get good for cheap before I splash out on fancy pants stuff, I’m not good enough to use.
It felt like a mountain to climb but I am determined to get their eventually.
Well this week I placed my first sectional matrix, it feels like a big moment and I thought I’d share the case with you. I’ve also finally worked out how to save our digital radiographs as J-pegs so I can finally show some root fillings. I’m not always sure showing root fillings is very exciting, you just know the person showing them only ever puts up the good ones. Well my root fillings are not always perfect and I’ll try to show some ups and downs as I go but generally the standard of this case is what I’m aiming for (at the moment) but I know there is room to improve.
The Case
So this case is on a 40 ish year old lady who was having some pain from her upper right tooth, she also had some food packing in the area and was not especially happy with her old dentist. When I examined the 14 tooth had a large defect I could probe right into distally and was tender to percussion. I could flex the distal portion of the tooth a little and I summarised that the tooth had a oblique vertical fracture, caries and acute apical periodontitis.
I was pretty worried that the fracture may run a long way subgingival so I made a deal with the patient that I’d remove the decay and fracture and see how deep it was. If I though I could restore it, I would. If not we’d have to look at other options but these were far from great: implant too expensive, didn’t want denture, 13 very poor root filling/ suspicious looking screw post. No chance of RBB from the 13, I didn’t fancy doing a fixed fixed on that 13 so a conventional cantilever off the 15 would probably have been the only option but I wouldn’t love the sound of that. So all in all I was pretty keen to try to save the tooth!
so next appointment we went in and removed the caries and fracture thankfully it was alot higher than I feared maybe 1 mm below the gingival margin and well within my comfort zone. I root filed the tooth both canals were narrow so I prepared the taper using my standard endo technique to a size 25 6% taper. The obturation is with AH Plus and matched points all done under rubber dam of course. Once I’ve sealed the canal I always condense vertically with just a glick instrument (I’m saving up for a system B), I then seal the tooth with vitrabond another material clever old Zaid taught me about and which I love to use to instantly get a good coronal seal even if I then temporise the tooth before final restoration.
However I was a bit nervous of just temporising this tooth as the margin was so subgingival and I wasn’t sure I could control my GIC there. I also didn’t want to have gingival overgrowth and poor cleaning as I was planning to crown the tooth later. Finally the patient had a complaint of food packing and when you look at the 15 amalgam it’s easy to see why. I wanted to replace this restoration. Ideally before I crowned the 14 so I could get a nice contact and to do that I’d ideally need something to build against.
So all in all it was time for the sectional matrix. I whipped off the dam added 2 new holes and took the dam back to the 16, added my sectional matrix and hey presto. I know it’s not as good as the one from zaid’s blog but it’s a great start. I had great moisture control in a difficult area, a good curve on the matrix and tight adaption
to the margins. Only about ten minutes ago I did, however, realise that I’d got the sectional matrix ring the wrong way round but you live and learn (and it still worked)!!
I don’t have a post op as I ended up running a bit late the composite looked good, you can sort of make it out on the post op radiograph?! It’s just a simple one shade composite (flow-able at the very bottom of the box) but well adapted and I hope it will last well!
Next visit I’ll replace the 15 filling but looking at that obturation picture it doesn’t look too clever endodontically. Also what would you do with the symptomless 13 the patient has previously wanted it changed for aesthetic reasons but was put off by one of colleagues which I think was fair enough but what would you do? Finally would you, having done that nice composite, crown the tooth? I regret to say hugely that I didn’t reduce the 2 cusps and take the composite over them (stupid I know). If I had would you leave it?
I’d love to know your thoughts?
I’d just like to make one more point. I read a lot of geeky dental books and I always think “wow it would be amazing to work like that” but that’s not real life dentistry. But then you start watching and talking to people who really do work like this everyday, all the time and once you know that it’s possible and you believe in the techniques…. I just have to challenge myself to use them everyday, all the time.
The trick is to get quick enough at them to make them everyday, fast and efficient. I really do think it’s possible; I’m working more and more under dam, polishing cavities before filling, bonding crown preps pre impression and other great ideas. You have to get efficient and find the time to make them part of your routine and not an extra hassle.
Maybe you already do all this stuff: to these readers I’d like to say, “I salute you, and ask you to please let me shadow you, I want you skills!” To others I urge you to give them a go, if you beli
eve in them of course.
Chris




#1 by Alex at March 4th, 2010
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That looks pretty nice to me Chris!
I probably would’ve done composite cuspal coverage as the isthmus is wider than the cusp width you’ve got left. As for the 13, is it caries under the margin distally or just a radiograph shadow? I know what you mean about leaving symptomatic teeth alone, especially when it’s a canine! I suppose the right thing to do would be to dismantle and investigate and warn her about flare up or root fracture when that horrid post comes out. Then you could crown the 13 and 14 together and get a nice shade match, with some group function to protect the 3? Or i suppose a gold onlay over the cusps of the 14 or indirect composite to save more tooth tissue.
Looking at the 16 it’s a fairly deep wide amalgam, the sort that fractures a cusp off and comes in as a broken tooth. I never know if a crown now would be best or to wait until the cusp fractures and then crown- which is better long term. I’ve just not got enough experience and i’m certainly not getting it now i’m stitching up drunks.
#2 by DundeeDent at March 4th, 2010
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Hey Chris,
Fantastic post! Following your last composite matric post I’v been looking for oppertunities to try it out on undergraduate clinic, still to no avail. One day though!!
Just a quick question regarding the placement of the clamp on the 6 in your photos, is the tip of the clamp not applying too much pressure to the walls of the tooth? I just remember being told something about possibility of fracture of the remaining walls of a heavily restored tooth, however with it being dental school it could well be a purely academic thing.
Look forward to seeing a post op of this!!
#3 by ChrisO'C at March 4th, 2010
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Dundeedent, I’ll be honest I’m not too worried about fracturing a big molar with a clamp like that but I did wince a bit when I saw the picture and I totally see your point. I think it’s far more important when the tooth is hollow like when your doing a root filling TBH.
I’ve recently ordered a load of dam clamps for the practice for this reason I just don’t feel I have enough options to cover the teeth nicely. They haven’t arrived yet and as you correctly say… one day!
Also that is my favourite clamp almost the only useful one and it ain’t the most springy these days, so I think I’m safe.
It’s a bit like I said earlier too. I put that dam on in about 2 minutes. Any longer and I wouldn’t have had time to use one. I do my best to get a nice clamp fit on the teeth but what can I say…. I’m working on it.
So in answer to your question, yes your probably right. There is a risk but in this case I would say a very small one and one I do try to avoid.
#4 by ChrisO'C at March 4th, 2010
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Alex, there could well be caries under the 3. I’ve only seen the patient for 10 minute urgent and 1 hr treatment so I’ve not prodded enough to be sure.
I think I probably will change it though, if she’s keen that endo is a real mess. I just was interested to hear other peoples opinions.
I take your point on the 6 but I think I would leave that for now on this patient as there are more pressing problems, I’ve just met her and I don’t want to overload her. I’d also prefer to do a gold crown TBH with it not having a root filling and being vital.
I’ve proactively crowned quite a few of these now and they’ve all worked out really well. Generally if the patient is keen, I am. Crowning these teeth just makes sense to me long term. I think the hard decision is deciding whether to replace the core before you start.
P.S. You love the maxfac, admit it!
#5 by Matt at March 6th, 2010
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Nice work again Chris, keep the cases coming. I love looking at stuff like this and enjoy even more considering the questions you ask.
I think you were right to advise endo for this tooth rather than loss and replacement and I would always do this in all but the most hopeless of cases. To achieve that quality of result in just one hour is also going some!
I think you need to vitality test 15. All three rads show an apparent apical lesion, I suspect the pulp is long gone. Endo will be a bit easier for this one – two canals joining mid root are clearly seen on your post op film.
Regarding restoration of these teeth, there is some evidence to say a crown may not be necessary for root filled premolar teeth though the wealth of evidence over many years would suggest it is far far safer to crown/cusp coverage. Amongst others, Mannocci did a study on premolars with fibre posts and direct composite vs full crown and had no difference in failure rates at 3 years.
Dr Simone Deliperi and Dr Liviu Steier have published some of their work reinforcing their post endodontic direct compsite with Ribbond, a UHMW polyethylene mesh; low levels of evidence for these case reports but google them and see for yourself. They look pretty promising to me.
So… fibre reinforced composite may (or may not) be the answer if patients can’t afford a crown or a tooth needs to be without a crown for some time or if their insurance doesn’t cover crowns. I think a common theme in the work of all these dentists is their meticulous attention to detail with moisture control, bonding agents, placement of composite/fibres etc.
For a direct composite as you did, if I was planning to leave it I I would probably have shoed the palatal (functional) cusp with composite and bevelled right up the buccal incline of the occlusal surface, aiming to keep the natural aesthetics of the buccal cusp intact whilst offering some degree of cusp protection. My evidence for this method: none! I am no more right than you were not to reduce the cusps, it is just an opinion.
Finally regarding the 13, I don’t think there is any reason for any of us to be disparaging about anyone else’s work on a public blog. Yes, the work is suboptimal but we don’t know the history; it could have been a VTs first ever post and core for all we know and surely we would want to be forgiven for that one! We’ve all had bad days, at least I know I have! At least the dentist didn’t take the soft option and extract and give a gum-stripper. The tooth has lasted long enough for it to be seen by someone who feels they have the skills and inclination to make it last another number of years and I think, above all that is great news for the patient.
I think it is a cast post rather than a screw post. Retreatment with magnification and system B would seem reasonably straightforward, if very time consuming but it may be difficult without these extras.
You can see there is a far more substantial post channel in the tooth than the post actually fills. If you can see to the bottom of this following post removal then the retreatment of the initial canal will be easy. If you can’t you may find your files just hitting the base of the existing post channel and only occasionally dropping in the canal. Following renegotiation and cleaning and shaping you will have a post channel already in place, obturation of the last 5mm with sytem B would take 2 mins and leave you with the post channel ready to go. What post to use??!
I would certainly not remove any more dentine for the post as you will probably have an over flared canal following post removal. Choose the DT light post with best apical fit and place additional fibre posts around it like lateral condensation of fibre posts. Do a dry try-in first to make sure you know how many/what order and then pre-inject a dualcure cement (eg Panavia F, Paracore etc) in and go for it with the posts (leave the operating light/headlamp off for that bit!). RTD make a mini quartz fibre post (fibre cone) designed for this purpose though in this case you may fit one or two smaller sized actual fibre posts around your master post, it depends how hollow the root is. All this said, the most important factor is that you have at least 2mm ferrule in your prep.
I hope some of this is useful and good luck!
#6 by Alex at March 6th, 2010
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Fibre post… really? I know all the theory but in reality do they really last long enough? especially in a canine with all that lateral loading. Plus in a previously RCT’d tooth is the bond strength going to be good enough?
I would want a cast post in this tooth. I do know it’s old fashioned though.
#7 by matt at March 9th, 2010
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Alex, I don’t know if the fibre post is the best option but it is what I would do. They are not perfect but if care is taken during their placement and more importantly care is taken to ensure a proper ferrule then I think they are a better bet.
I never use cast posts as I don’t like the break in the aseptic chain a cast post necessitates firstly during impression and secondly with the leaky temporary in place. I believe all work in root canals should be done with a dam, and post-core build ups straight after obturation where possible. Also there is a very high risk of root fracture given the hollowed out root and shear stresses you mentioned.
Bonding to intraradicular dentine is a problem but that is mainly due to the ridiculously high C-factor of a root canal. The presence of a GP/sealer rich smear layer is a concern as is the presence of an oxygen righ layer and altered dentine surface due to NaOCl used during endo. Creation of the post channel with system B minimises the smear layer created and irrigating the post channel with CHX is preferable to NaOCl as will not impede bonding.
The question is will any option last long enough for a tooth like that??
#8 by Dental Philippines at March 20th, 2010
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Im using that also, but you can get something like that quite cheap in ebay, have seen that here:
http://cgi.ebay.de/ws/eBayISAPI.dll?ViewItem&item=220566371184&ssPageName=STRK:MEWAX:IT
its around 3 dollars per clasp, the guy is also selling the matrix system.
#9 by Saylor at May 10th, 2010
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Chris,
I just stumbled onto this blog and I have to say I’m very impressed with the posts I’ve been reading. Bookmarked the site so I can check it out later on.