Dental Crowns
 

Appointment 3. Cementing the Real Crown

This tends to be a much shorter appointment.

Anaesthetic is required if the tooth is alive as it can be very sensitive once the temporary crown has been removed. This is probably not needed if the tooth has had root canal therapy but some dentists like to put some in anyway for peace of mind.

The temporary crown will then be removed- sometimes it can be levered off and other times it may have to be cut off. The tooth underneath is then cleaned to remove all traces of temporary cement and the permanent crown tried in.

The dentist will assess:

  • The margins- is the crown sitting down fully on to the tooth preparation?
Here we run a probe from the tooth onto the crown- the probe should not slip underneath but pass smoothly from one surface to the other. If the margins are above the level of the gum, then you may be able to feel where the tooth and crown meet.

  • Are the contacts points good?
You should be able to hear a definite click as floss is passed through. If this is not present then there is a chance that you might get food stuck in this area.

  • Is the shade correct?
Often I will sit the patient up in the chair, particularly if it is a front tooth and have them check they are happy before we stick the crown in.

  • Is the bite correct?
To check this, they will put the trusted blue bite paper in between the teeth and get you to tap your teeth together and slide your teeth across each other. Any high spots will be adjusted and the porcelain re-polished. In an ideal world (which unfortunately we don't live in) the porcelain isn’t adjusted at all- this maintains the maximum glaze and means minimal wear will occur to the opposing teeth.

On rare occasions, it may be necessary if the bite is very tight to adjust the tooth or teeth that bite onto the crown. It is better to adjust a filling than natural tooth but sometimes we don't have a choice. This is done as a last resort when further adjustment of the crown may compromise the crown’s strength or reveal the metal underneath if the tooth is a porcelain fused to metal crown. If the opposing tooth is on a denture or is also a crown, it can easily be adjusted.


Cementing and bonding-in:

Once the dentist and you are happy, the crown can be cemented or bonded in. This depends on the circumstances and the type of crown used. Different procedures are followed for each, materials can be chemically cured (i.e. set on their own) or light cured (set with the blue dental light) and are either a glass ionomer cement, a composite resin or some combination of the two.

Cementing a crown is like using a super strength glue to connect the tooth and the crown. Bonding is stronger and involves the same technology as composite fillings –both the inside of the crown and the tooth are etched with an acid to create micro pores which the material then flows into and sets to firmly attach the two together.

We use bonding and cementing in different circumstances. One is not necessarily better than the other- more they are appropriate at different times. If the crown preparation is short and tapered, there is not a lot of natural shape to hold the crown in, so to get some extra retention we may consider bonding. On the other hand, bonded crowns are considerably more difficult to remove which can cause damage to the tooth underneath in the process if it needs to be taken off. Because of this, for a naturally retentive tooth preparation, cementing will be more than adequate. As with everything, different dentists have different preferences!

During the process of sticking the crown in, it is essential that the tooth remains completely dry so the dentist will pad you out again with cotton wool, dry tips and a saliva sucker, or isolate the tooth with rubber dam.

They will dry the tooth with air, then follow the instructions of the particular cement they have chosen, ultimately mixing the material, putting it into the crown and seating it down on the tooth. When correctly in place they will remove the excess cement and floss in between the teeth to ensure material doesn’t set here. Sometimes with light cured materials they will shine the blue light for just a couple of seconds to allow the excess to be peeled away more easily before setting it fully.

Once the material has sufficiently set, the margins will be polished with burs, the contacts flossed to ensure they are clear and the bite checked again and adjusted if necessary. And hey presto! The procedure is complete.

Will I get Pain After the Crown?

Not really- sometimes a bit of soreness from the gum or perhaps a bit of sensitivity if the tooth hasn’t had a root filling. Everything should be back to normal within a couple of days. If you have also had a root canal as part of the treatment then the tooth may take a bit longer to settle down.

Sometimes when you are numb, it is not always that easy to get you to bite in your natural position and so the crown’s bite may not be adjusted fully. If after the anaesthetic has worn off, it feels high, give it a few days to settle down, but if the feeling persists, return to your dentist who will make the necessary adjustments and polish it down to the correct level.

It is also possible the crown feels a little rough after cementation once the anaesthetic has worn off. Often this will smooth down naturally after a couple of days of normal eating and chewing. If the feeling persists, pop back to your dentist as there may be a little bit of excess cement remaining.

How should I Care for my new Crown(s)?

Is there anything I should or shouldn’t do? Can I eat?

You are pretty much good to go. A crown will allow you to eat, chew and smile as normal, pretty much straight away. If you are a bruxist and grind or clench your teeth you should be wearing a night splint anyway, but if you have had crown and bridge work it is even more important you get one made (and wear it!).

The anaesthetic will take a few hours to wear off- just be careful during this period. Avoid hot things because you will not be able to tell temperature and chew slowly so as to not bite your lip if you really must eat. Ideally wait till it has worn off before having food.

You need to look after you crown or crowns just as you would any natural tooth with good brushing and flossing.

It is a good idea to reflect briefly on why the crown was necessary- if it was because the tooth was heavily broken down, how could you have taken steps to prevent this from happening in the first place. What preventative care could you have done?

For example if the crown was needed because of a root canal treatment on a molar tooth for protective purposes, why did you have to have a root canal and how can you prevent this from happening again? If it was a cracked tooth because of grinding- then you should get a night splint made; if it was because of a very heavily filled tooth then chances are the cause was dental decay, so frequent dental visits, better cleaning, flossing, good diet and fluoride are key to avoiding having to go through this again!