Cracked tooth- Metal Band tips
Today I had to cement a metal band around a virgin lower 6 with a distal crack into the pulp. Difficulties I've had in the past with metal bands were:
- Band selection: Today I used a periodontal probe to measure the mesial-distal dimension of the tooth. The issue with the probe I had was the measurements didn't go far enough to measure the whole tooth in one go so I had to guess the last few millimetres. ensure you use a proble that has measurements far along enough to measure the entire width of the tooth. The mesiodistal width is the most important measurements to fit snugly as the width of the band is often limited by the position of the adjacent teeth. Ensure you measure from the widest part of the tooth not the marginal ridge as the band has to fit all the way past where the contact point is. The more worn the occlusal surface of the tooth the closer the occlusal table dimension will resemble the widest part of the tooth. With a tooth that isn't worn significantly it is easy to underestimate the width of the tooth.
- Forcing the band onto the tooth through the contact point: In the past I had put separators between the contact point and got the patient back after a few days to cement the band. The issue still remained that the band didn't adapt well in the interproximal areas. If there are interproximal restorations it is easy to cut them back to open the contact point. Today as the tooth was under heavy load (patient was a bruxer), the crack was into the pulp necessitating root canal therapy, and a crown was planned in the future anyway I found it prudent to slice open the interproximal contact as though I was performing a crown preparation. Initially I didn't cut it back enough ad I could fit the band most of the way down but it was still getting caught up on one of the contacts. After slicing the contact points completely open it was incredibly easy to fit the band. Most of the issues with metal band fittings is the contact point and once this is removed there is no resistance to seating from the contact point nor any discrepancy between the band width and the tooth width.
- Not putting enough cement onto the band and ending up with gaps between the band and tooth: My technique today was to put the put the band on the tip of my left index fingerheld in place with my thumb and middle finger. My index finger sealed the end while I injected GIC around the band walls. I then injected whatever was left in the interproximal areas. What I would do differently in the future would be to put the occlusal aspect of the band facing down towards the tip of my index finger so that I don't have to fiddle with it to flip it overbefore I can seat it in the mouth. From that position I don't need to take it off the finger and can plop it straight onto the tooth in question. The other thing would be to put more GIC around the tooth on the buccal and lingual aspect below the height of contour. Due to the flowable viscosity of cementing GICs, As the band is seated, the GIC may not flow around the curvature of the tooth and you may end up with a void under the height of contour and the band which you won't be able to see. This means that you won't get as much benefit from the encirclement of the band as there is space for the crack to open into as the tooth is loaded. Also if the band is too well fitting, as the band scrapes across the height of contour as it is seated, it may not leave room for the GIC to flow down and the hydraulic pressure from the seal can extrude the excess GIC from the occlusal aspect which again results in a large void allowing food trapping as well.
-I had a discussion/disagreement with colleagues as I see much more benefit in providing a temporary crown for a symptomatic cracked tooth. My rationale is if you intend on crowning the tooth anyway, just skip the medium step for a restoration that adapts a lot better, irritates the gingiva less and is more cleansable. A few years ago I would have considered this less conservative but I had less confidence in my diagnostic and technical skills. If the options are either between providing a crown (if the tooth is restorable) or extraction (if it is not) then there is no point avoiding preparing the tooth by placing a band. It is less invasive to prepare the tooth for a crown than to extract the tooth after employing the less effective option. However, I do admit that this opinion proably stemmed with my past issues with metal bands. A well placed and well executed metal band should provide a minimally invasive way to confirm the diagnosis of a cracked tooth. It is very useful in cases where you are unsure of the diagnosis and want to avoid unnecessarily preparing the tooth.
thank you I was researching on metal bands and this really helps a lot! what would you suggest for case where patient is symptomatic on eating, confirmed with pain on release on DB DL cusps, has only one very mild crazeline along marginal ridge on a first molar? would you still go ahead and crown/place temporary crown?
ReplyDeleteHi Michelle,
DeletePersonally, I have fallen out of favour lately with metal bands partly because of the difficulties I had with them, partly because I was using them as a diagnosis confirmation and I have gotten a lot more comfortable with my diagnosis. To me they are just that, a way to confirm your diagnosis because I don't think anyone would suggest that we should leave a metal band around a tooth for many years.
Eventually, once your diagnosis is confirmed, you should proceed with the appropriate therapy which arguably should be chosen based on the depth of the crack and the symptoms the patient is experiencing. You need to also consider the forces that will be placed on the tooth in question to try to mitigate future spreading of the crack.
1. This involves studying the occlusion-->are there any interferences on this tooth? Often you will see an angular wear facet on the cracked cusps. Is there an opposing plunging cusp?--> best viewed from the anterior looking directly back along the occlusal plane. Is there some form of guidance to protect posterior teeth?-->using articulating paper/film or mounting models to study this aspect. Are there enough residual teeth to support this tooth in function?--> check missing teeth and the periodontal health of anteriors which can also reduce the effectiveness of the anterior guidance (think fremitus).
2. The symptoms will often give you the depth of the crack. If it is just a mild craze line as you suggest, I doubt the patient will be experiencing significant discomfort. Almost by definition, if the patient is experiencing symptoms with a cracked tooth, the crack must be extending past the DEJ. You will need to check with transillumination to see if light passage is interrupted. This will give you an idea of if the dentine is involved. I won't treat enamel craze lines as this is generally a common and inconsequential finding. Cracks into dentine are a different matter, they have the potential to cause symptoms and spread. Especially cracked virgin teeth, and especially cracked virgin 7s and 4s I would tend to be more aggressive as the fracture endpoint is usually a split tooth. For a virgin cracked 6, it would depending on if there is a 7 present to support it. It doesn't have to be a 7 to be at risk, 7s are generally at risk as they are the terminal teeth, closest to the elevator muscles, but if the 8s and 7s are missing, the 6s are at risk of catastrophic fracture as well.
3. Of course, the patient decision needs to be considered. Some are more proactive and some are more reactive. You just need to make them understand the situation and be aware that the problem with watching and waiting may be that we may end up with an unsalvageable situation.
Specifically with your situation, if there is any doubt about the diagnosis, feel free to place a metal band and monitor for symptoms. If there is an obvious cause for the crack, I would also be addressing that. If you feel the crack needs splinting, you can also try that first with a small composite restoration before you commit to a cuspal coverage restoration. You may need to make space with a small odontoplasty or adjusting the opposing.
These decisions are just based on your confidence in your diagnosis and your appetite for risk. If there is any doubt, stick to your principles and tend towards doing less rather than more.