composite vs amalgam

[Kniles5]

okay, so everyone I know who has gotten a composite filling on chewing surfaces has had to get it replaced or has gotten an infection that lead to a root canal. Why do dentists give composite fillings on chewing surfaces? Composite is plastic, amalgam is metal. It might be ugly, but it is superior in utility. Aesthetics or utility? As medical professionals, we should go for the utility. I guess some dentists like the fact that composites make them more money. Is there a good reason?

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[toysareus]

okay, so everyone I know who has gotten a composite filling on chewing parts (molars) has had to get it replaced or has gotten an infection that lead to a root canal. Why do dentists give composite fillings on chewing surfaces? Composite is plastic, amalgam is metal. It might be ugly, but it is superior in utility. Aesthetics or utility? As medical professionals, we should go for the utility. I guess some dentists like the fact that composites make them more money.

OHHHHHHHHH BOYYYYYYYY.....

 

[Kniles5]

OHHHHHHHHH BOYYYYYYYY.....

What did I hit one of the unmentionables in dentistry? I was just wondering!!!
JEEEEEZ I just wanted a good reason why it is done. I also wanted to know if you all think that I am wrong. I guess that is apparent.

 

[Dr. Dai Phan]

okay, so everyone I know who has gotten a composite filling on chewing parts (molars) has had to get it replaced or has gotten an infection that lead to a root canal. Why do dentists give composite fillings on chewing surfaces? Composite is plastic, amalgam is metal. It might be ugly, but it is superior in utility. Aesthetics or utility? As medical professionals, we should go for the utility. I guess some dentists like the fact that composites make them more money. Is there a good reason?

Amlagam is the material of choice for restorations of chewing surfaces especially in the molar regions. Composite material is too weak to support the load so over the years, composite restorations in these areas tend to break and increase the risk for recurrent caries. I have seen TONS of MOD composites that either leak or fail over the years that all end up need replacing. I believe that placement of composites indiscriminatetly in the molar areas is a disservice to a patient. However, many dentists still do because it generates higher profit than amalgam. When I was in my AEGD program, I was told to place composites in areas that were highly questionable such as in functional cups or in areas that moisture control was impossible. When I questioned about the choice of material, one professor told me to "Shut up and do as you are told!". DP

 

[aphistis]

Aesthetics or utility?

Faced with the decision, which one do you suppose most people in modern-day America will choose? That's why.

 

[backaction]

Think of all the dentists out there that place posterior composites without rubber dams. Then think about how many were contaminated with blood, saliva or excessive moisture. We all know damn well that a lot of these were still light cured with heme flowing into the proximal box. Then 1-2 years later they are all discolored, and have leakage and they have failed the patients. And what about the composites that overflow past the prepared tooth margin when placed. You polish it, but can't tell where the real tooth-restoration interface is (cavosurf.). It feels smooth, and then it gets leakage and fails. The operator makes a huge difference, but even so, amalgam is superior in most situations. What are peoples opinion about composite cores? Do composite cores make good cores when the tooth is going to be a bridge abutment or would you always use amalgam or cast metal? Also, what are people using when someone has a posterior crown with decay under the margins, and the patients doesn't want the crown replaced? Are you removing caries and then placing amalgam or GI.

 

[lgreen_aci]

I hope I don't touch a sore spot here, but I'm a curious predent.

What about concerns over mercury toxicity w/ amalgam?

Also aren't some of the newer composite materials supposed to be more on par w/ the strength of amalgam?

 

[DDSSlave]

I have seen TONS of MOD composites that either leak or fail over the years that all end up need replacing.

And I've seen a lot of MOD amalgams with recurrent decay or fractures (usually due to inadequate pulpal floor depth). Most restorations at some point or another need replacing, it's a matter of how many years. With modern composites, it's impossible to estimate (extrapolate) how long that will be anymore. I still tell my patients that composites will need to be replaced sooner than amalgams.

BTW, to the op, composites are not plastic. They do wear considerably more than amalgams (at least historically), but you can bond in a composite which has it's advantages. There are good and bad points to both materials. In general I'd advise amalgams for molars, but it's only a matter of time and research until that changes.

 

[DrJeff]

Amlagam is the material of choice for restorations of chewing surfaces especially in the molar regions. Composite material is too weak to support the load so over the years, composite restorations in these areas tend to break and increase the risk for recurrent caries. I have seen TONS of MOD composites that either leak or fail over the years that all end up need replacing. I believe that placement of composites indiscriminatetly in the molar areas is a disservice to a patient. However, many dentists still do because it generates higher profit than amalgam. When I was in my AEGD program, I was told to place composites in areas that were highly questionable such as in functional cups or in areas that moisture control was impossible. When I questioned about the choice of material, one professor told me to "Shut up and do as you are told!". DP

Normally Dr D.P. and I are "eye to eye" on most topics,and I'll admit that there alot of validity in the above post. HOWEVER, to play devil's advocate on this topic....

Composite restorations historically have shown a greater wear rate and a higher failure rate than amalgam restorations, however I've personally seen (almost daily) many failed amalgam restorations also. One of the largest problems with composite restoration IMHO, is that in their early days, both the material's physical properties and our lack of understanding of their extreme atention to placement detail were woefully inadequate. Early generation composites (or more appropriately silcate cements) had awfull wear rates, poor esthestics, and were very technique sensitive in their placements. early generation (even up through 3rd and 4th generation) bonding agents were complicated to handle/mix/apply and had much lower bond strengths than todays most commonly used 5th, 6th and 7th generation adhesive agents. Lastly, the MAJORITY of todays practicing dentists were not trained from day 1 of restorative class in dental school to use/handle composite as a posterior restorative material Hence, much of their knowledge of placement technques have come from lectures, raher than hands on training, and many "old timers" don't like to always read/follow the directions as wel as they should. These factors have accounted for(and still account for today) much "operator error" with composite restorations.

Those points out there, with todays modern day micro-hybrid and micro/nano-fill composites placed incrementally, coupled with a 5th/6th or 7th generation bonding agent placed with a total etch technique, and STRICT moisuture control, on an approprite tooth, can (and do) last as long as/wear as well as an amalgam restoration. Are you just as likely to get a posterior cusp fracture if you place a large (buccal - lingual) width MOD composite as an amalgam, sure, but thats all in treatment planning and the fact that a large restoration like that realistically should have been restored initially with some type of indirect restoration (onlay/crown) as opposed to a direct restoration. Can a composite restoration have more post placement senstivity than an amalgam, yes, but most of the time, it will be from either a) inadequate quantity of bonding agent (i.e. non complete sealing of the dentinal tubules) or b) occlulsal interferences.

In my practice, with respect to posterior direct placement restorations, I place roughly 40% composite and 60% amalgam. I give the patient the choice, with the following disclaimer where I tell them if even with rubber dam or isolation via an isolite (great product ) that I can't keep the area 100% dry (deep subgingival box where I can't adequtely control leakage with either laser cautery or retraction paste, or they're heavy salivators) then amalgam is going in that tooth. If they still want a tooth colored restoration then we talk about some type of indirect porcelain restoration. I use a total etch technque, place a glass -ionomer liner (Fuji LC liner) on any dentin, use a 5th generation bonding agent (Bond-1 from Jeneric Pentron), place a 1st increment of flowable composite before I place the bulk of the composite to restore the tooth (I use either Point 4 from Kerr or Vitalesence from Ultra dent) and then after final restoration contouring/polishing I re-seal the restoration with Shine n Seal from Pulpdent.

The key is all in treatment planning and then attention to details, and failure to do either of those well, can and often does lead to the failures that we all hate to see.

 

[Biogirl361]

I'm not as experienced in the matter as some of the other posters, but i feel like this:

1. patients demand the "white fillings" not only for esthetics but because of all the bad press that amalgams have gotten, patients come in convinced that the metal fillings are toxic and all that and don't want them and even sometimes want their good amalgams removed in favor of composites.
2. so many dentists and dental students don't use rubber dams or other adequate isolation, its no wonder the composites are going to fail.
3. research results are varied but some studies indicate that composite may help strengthen the prepped tooth structure somewhat. if this is true it might theoretically actually be better to use in the posterior.
4. The fact that it is bonded might decrease leakage/recurrent caries. also, the margins on composites i've done/seen are are much more well sealed than on the amalgams and are smoother so they don't trap plaque.
5. Less sensitivity/pulpal insult since composites don't conduct temperature like amalgams. they also don't expand and contract like amalgams, so less flexing force on the tooth. the lower amount of leakage and better sealed margins that i mentioned before might also contribute to lowered sensitivity.
6. composite allows for much more conservative preparations because of it's bonding ability (you don't need to cut to a minimum depth and add mechanical retention features like extra grooves to hold it in) and anything that lets you preserve tooth structure is a plus.

As far as i know, actual research on amalgams vs. composites is many and varied, I am not aware of any one definite conclusion yet, which is why this topic is still controversial

ps - yeah i think that longevity of restoration has a lot more to do with size and design of the preparation than the material they are filled with, assuming proper technique was used with with either material. no materials are as good as natural dentin and enamel

 

[Dentcraze]

okay, so everyone I know who has gotten a composite filling on chewing parts (molars) has had to get it replaced or has gotten an infection that lead to a root canal. Why do dentists give composite fillings on chewing surfaces? Composite is plastic, amalgam is metal. It might be ugly, but it is superior in utility. Aesthetics or utility? As medical professionals, we should go for the utility. I guess some dentists like the fact that composites make them more money. Is there a good reason?

I dont think that dentists make more money with composites than amalgams. Amalgam is cheap and only comes in one shade. Composite comes in alot of shades and you have to buy other materials. Class 2 composites take longer. So I dont think that dentists do them to be greedy. If manufactures guidlines are followed you can get a long service time out of composite. There are some studied that suggest that composite strenghtens the tooth internally.

 

[gryffindor]

I dont think that dentists make more money with composites than amalgams. Amalgam is cheap and only comes in one shade. Composite comes in alot of shades and you have to buy other materials. Class 2 composites take longer. So I dont think that dentists do them to be greedy. If manufactures guidlines are followed you can get a long service time out of composite. There are some studied that suggest that composite strenghtens the tooth internally.

These are good points. I despise doing direct composite restorations, especially class 2. While I'm sitting there trying to keep the saliva out and am holding the curing light for what seems like an eternity for incremental fill, I think of the time & backache I would have saved if I could just shove an amalgam in there. I think a lot of times patients wouldn't care what the filling material is but the office dictates "white fillings" so I am stuck with it.

 

[DrTacoElf]

I'm not as experienced in the matter as some of the other posters, but i feel like this:
4. The fact that it is bonded might decrease leakage/recurrent caries. also, the margins on composites i've done/seen are are much more well sealed than on the amalgams and are smoother so they don't trap plaque.
5. Less sensitivity/pulpal insult since composites don't conduct temperature like amalgams. they also don't expand and contract like amalgams, so less flexing force on the tooth. the lower amount of leakage and better sealed margins that i mentioned before might also contribute to lowered sensitivity.

Just something to point out here. Amalgams oxidize/corrode over time which gets you a better margin seal than you initially have in terms of micro/nano structure. True composites don't expand or contract as MUCH as amalgams but something else to worry about is the C factor. Professors have shown us clinical cases of Class 2s where the shrinkage of the composite material has broken cusps; and this was with proper placement.

Point being that there is not the perfect restorative material and its up to the operator to deal with the sitiuation and the patient in order to come up with a suitable plan of action

 

[DrJeff]

Just something to point out here. Amalgams oxidize/corrode over time which gets you a better margin seal than you initially have in terms of micro/nano structure. True composites don't expand or contract as MUCH as amalgams but something else to worry about is the C factor. Professors have shown us clinical cases of Class 2s where the shrinkage of the composite material has broken cusps; and this was with proper placement.

Point being that there is not the perfect restorative material and its up to the operator to deal with the sitiuation and the patient in order to come up with a suitable plan of action

The composite curing shrinkage can be a BOG factor in post filling sensitivity. The best (and probably easiest) example I've seen as to how much composite can shrink upon curing was a demonstration I saw at a continuing education course given by Dr. Paul Belvedere (owner of Cosmosdent, and a well respected dentist in the field of composite esthetics). What he did was take an empty anesethetic carpule and fill on end up with composite to a depth of roughly 3 to 4 mm. He then cured the carpule from the side (through the glass), and you could see the composite shrinking towards the curing light and the far side had pulled away from the glass of the carpule between .5 to 1mm One of the postulations as to why sensitivty occurs with composites is this shrinkage putting the restored tooth cusps under tension.

 

[12YearOldKid]

okay, so everyone I know who has gotten a composite filling on chewing parts (molars) has had to get it replaced or has gotten an infection that lead to a root canal. Why do dentists give composite fillings on chewing surfaces? Composite is plastic, amalgam is metal. It might be ugly, but it is superior in utility. Aesthetics or utility? As medical professionals, we should go for the utility. I guess some dentists like the fact that composites make them more money. Is there a good reason?

Some of these issues have been addressed already, but I thought I'd chime in. First off, if you live long enough all fillings need replaced.

In the past amalgams tended to last longer than composites, but that is in question with the latest generation of composites. When placed properly there is very little compromise in placing a posterior composite instead of an amalgam. We can have utility AND esthetics.

And composite is superior to amalgam in more ways than just being tooth-colored. Composites allow a much more conservative restoration when compared to amalgam preps. I recently chose to have a posterior composite placed in my own mouth. I am aware that it MAY need to be replaced sooner, but it sure beats having my tooth blasted apart to make room for amalgam when composite allows us to make a tiny little prep just big enough to get rid of all the decay. When I have that restoration replaced in 10 years or so the preparation will probably still be smaller than if I had just gotten amalgam in the first place.

As for making more money with composites --- I seriously doubt that. Posterior composites are difficult, technique sensitive, and time consuming. The fees for composites are only slightly higher than for amalgams but take a LOT more time if done correctly. It is much simpler and faster to just put in an amalgam and send the patient on his way. Oh yeah, some insurance companies have a policy of downgrading all posterior composites to amalgam fees anyway.

 

[toofache32]

I hope I don't touch a sore spot here, but I'm a curious predent.

What about concerns over mercury toxicity w/ amalgam?

There are no concerns over mercury toxicity with amalgams. If you're worried about mercury then stop eating fish and drinking city water because that's a much larger source of mercury.

Don't let the media make you their b!tch. They can make you believe anything they want you to. But so can I....what would you say if someone told you to take rat-poison to keep you from having a stroke?

 

[Biogirl361]

ya, amalgams do corrode to seal the margins, but doesn't that take some time like 6 months or so? as far as composites, how much do you all think incremental fill and ramp curing helps as far as decreasing shrinkage effects on the tooth? what about placing a sealant over the restorations in the posterior?

 

[HuyetKiem]

what about placing a sealant over the restorations in the posterior?

I have a sample of Embrace WetBond Seal-n-Shine. According to the rep, it was designed for sealing, finishing and polishing composite restorations by bonding to both tooth structure and compsite. Anybody has any experience with this product ?

 

[ShawnOne]

Some thoughts:

4th Generation adhesives (seperate etch, primer, and adhesive) are shown to create the highest bond strengths, especially in dentin, 54MPa compared to 24MPa in 7th generation (which is all-in-one). We only use 4th gen at USC.

We use an immediate dentin sealing technique. Basically, we immediately seal the dentin right after it is cut. This is to avoid contamination and create the hybrid layer without collapse of fibrils. This strengthens the bond to dentin and reduces leakage and sensitivity.

We are also taught the semi-direct technique for posterior composites. Basically making a composite onlay/inlay which is pre-polymerized and luted into place. This is to minimize shrinkage only to the luting material.

 

[12YearOldKid]

We are also taught the semi-direct technique for posterior composites. Basically making a composite onlay/inlay which is pre-polymerized and luted into place. This is to minimize shrinkage only to the luting material.

That's interesting. We were taught that technique as well. But it was kind of a "hey guys, here's something cool --- but you'll never really do this."


I really like the idea, but wonder if it is something that would be feasible in private practice and still charge your regular direct fee. If you are experienced with this technique, how much time does it take compared to the traditional direct fill?

BTW, we only use 4th generation adhesives too. After our dental materials course, I think that is the system I will use when I get out into practice too. It's the least technique sensitive and provides the highest bond strength.

 

[DrJeff]

That's interesting. We were taught that technique as well. But it was kind of a "hey guys, here's something cool --- but you'll never really do this."


I really like the idea, but wonder if it is something that would be feasible in private practice and still charge your regular direct fee. If you are experienced with this technique, how much time does it take compared to the traditional direct fill?

BTW, we only use 4th generation adhesives too. After our dental materials course, I think that is the system I will use when I get out into practice too. It's the least technique sensitive and provides the highest bond strength.

That technique is basically like doing a regular old composite, the only difference is that the particle size in your composite is HUGE rather than quite small . Afterall all a composite is is plastic particles embedded in a resin matrix, and the main difference between composites on the market is the size of the particles, in general, the smaller the particles, the smoother the final finish you can get. That's why I like using a microhybrid.

As for bonding agents in private practice, the majority of practioners are using a 5th generation adhesive (combined primer and adhesive in 1 bottle with a seperate acid etch) This saves you time from not having sperate primer coats/air dry and then adhesive resin coast air dry + light cure. If your doing a quadrant of composite, you might very well save 5+ minutes per patient with this type of adhesive. Many practioners who aren't as judicous with their application of bonding agent and get post placement sensitivity are graviting to the 6th and 7th generation self etching primer/adhesives (i.e prompt l-pop, i-bond, clearfill se, etc). These self etching adhesive agents basically create a hybrid smear layer at the dentinal tubule/resin interface which helps promote full dentinal tubule sealing and less sensitivty. The trade off is lower bond strengths and you can't use them for self cure cements/restorative materials.

I'm a big fan of 5th generation bonding agents, and swear by my Bond-1 (Jeneric pentrons product). I've been using it since my residency back in '97-98, and have had a successful, predictable almost 9 year track record with it. Sure, every now and then I'll buy a bottle of an interesting looking new 6th or 7th generation bonding agent, but what typically happens is less than a week lter I'm telling my assistant to break my Bond-1 back out, and about a year later that roughly $100 dollar bottle of 6th or 7th generation bonding agents(that's basically what a bottle costs ) gets thrown out when we do spring cleaning. One thing that in general we dentists do, because of the fact that we tend to like new "toys", is aquire many new cements/bonding agents/types of composites, which we try and then go back to our standards. The new "toy" then gets put into the referigerator, and before you know it your either throwing alot of things out or getting a bigger refrigerator to store everything in For example between my partner and I we have 10 types of cements (basically we use only 2 for 98% of our restorations), 5 or 6 types of bonding agents (we use our beloved Bond -1 99.9% of the time), 7 types of composites (we use 2 types 98% of the time) and 6 or 7 types of impression materials, not including good 'ol alginate ( we use 2 types 99% of the time). Now we're starting to accumulate lasers , we just bought our 2nd and 3rd ones, an erbium and a diode to complement our nd:yag laser that we've had for almost 4 years now. Really, really cool using the erbium to prep a tooth WITHOUT anesthesia and having the patient be totally comfortable (especially little kids). After using it for a few weeks now, we don't even think twice about the $70,000 price tag

 

[ShawnOne]

That's interesting. We were taught that technique as well. But it was kind of a "hey guys, here's something cool --- but you'll never really do this."


I really like the idea, but wonder if it is something that would be feasible in private practice and still charge your regular direct fee. If you are experienced with this technique, how much time does it take compared to the traditional direct fill?

BTW, we only use 4th generation adhesives too. After our dental materials course, I think that is the system I will use when I get out into practice too. It's the least technique sensitive and provides the highest bond strength.

Its definately more time consuming. First your prep must taper, so you must block out any undercuts. Then you take an alginate impression and pour it with PVS (so now you have a positive in PVS). Next you build the restoration to full contour in the PVS and cure it from all directions. (we also slice the PVS between each tooth [like a die] so we can perfect the interproximals) Optionally, after curing, you can put the restoration in the oven for maximum hardness. Then you releive the internal a bit, and then finally lute it. This technique (along with layering techniques using dentin shade, enamel shade, and stains) was taught starting the 2008's in our new "Esthetics and Biomimetics Restorative Dentistry" course.

I would susptect the fee would probably fall in between a direct comp and a lab fabricated onlay/inlay.

 

[ElDienteLoco]

Some thoughts:

4th Generation adhesives (seperate etch, primer, and adhesive) are shown to create the highest bond strengths, especially in dentin, 54MPa compared to 24MPa in 7th generation (which is all-in-one). We only use 4th gen at USC.

We use an immediate dentin sealing technique. Basically, we immediately seal the dentin right after it is cut. This is to avoid contamination and create the hybrid layer without collapse of fibrils. This strengthens the bond to dentin and reduces leakage and sensitivity.

We are also taught the semi-direct technique for posterior composites. Basically making a composite onlay/inlay which is pre-polymerized and luted into place. This is to minimize shrinkage only to the luting material.

Maybe I'm missing something, but how does curing a glob of composite in PVS eliminate polymerization shrinkage? It seems like the composite still shrinks. Is it because the PVS deflects a little bit so that you're indirect restoration really starts oversize before polymerization shrinkage? It sounds like an interesting technique (although not very useful clinically), but why not have your lab do it in porcelain since it's almost the same process?

 

[ItsGavinC]

People can bag on posterior composites all they want, but I think a great deal of the success with these materials comes with knowing how and when to use them. There ARE situations where posterior composites do very well.

Likewise, I've seen MANY large amalgams in the posterior that should have never been placed--those teeth should have been crowned. I could argue that those large amalgams have led to crown fractures, or teeth now in need of endo, post/core.

I believe there certainly are good uses for composites, especially in the posterior, and especially with the wide arrray of materials we have available. No longer should we just be placing an MOD composite in the posterior, but we should be placing a glass ionomer base, then flowing some unfilled resin in the prep to coat it, then placing a packable composite in such a manner that when it's cured it doesn't pull away from the axial walls.

And of course, amalgam can fail as well, especially if it isn't placed properly.

 

[ShawnOne]

Maybe I'm missing something, but how does curing a glob of composite in PVS eliminate polymerization shrinkage? It seems like the composite still shrinks. Is it because the PVS deflects a little bit so that you're indirect restoration really starts oversize before polymerization shrinkage? It sounds like an interesting technique (although not very useful clinically), but why not have your lab do it in porcelain since it's almost the same process?

yeah, I guess you are missing something...

First off, you are not completely eliminating shrinkage, you are limiting it to the luting material. The key is that the shrinkage happens OUTSIDE the mouth. So the only shrinkage you get INSIDE the mouth is in the thin layer of composite you are using to lute the pre-shrunken restoration into place, which is a fraction of the total shrinkage you would get if polymerizing the entire thing inside the mouth. This allows you to avoid stresses of the tooth caused by shrinkage (avoids the restoration pulling on the internal walls as it shrinks), especially in large restorations.

We use the same concept when making a provisional for a pontic. A pre-hardened peice of acrylic is inserted in the pontic area of the stent to minimize shrinkage...

 

[ShawnOne]

Oh yeah, about it not being useful in clinic. I dont think it will change the way we do every single posterior composite, but as with everything in dentistry, i'm sure it will have its indications. And the advantages over porcelain are; its done in one visit, so no provisionals, and its less expensive since you dont need a lab to do it. However, its generally not as strong as porcelain and less esthetic.