Onlay or Crown?

[David L.]

Hi, I have a molar that has been achy for weeks. My dentist says it needs a crown. The tooth is worn from grinding but has no cracks, chips, etc. and has never been filled. The dentist said filling is not an option due to the size of the divot and my grinding history. I’d prefer an onlay over a crown but his office does not offer an onlay option. I’ve considered finding a dentist who does onlays but first I’m wondering if an onlay would work on this tooth (#19)?

Also, if a molar is prepped for zirconia, porcelain could the prep still support a gold crown at a later date? Or would the zirconia, porcelain prep remove too much tooth to redo the crown with gold? Thanks.

 

[MattKW]

That is a typical erosion lesion, caused primarily by the intake of acidic foods and drinks, e.g. soft drinks, sports drinks, citrus fruits and drinks, chewable Vit C tabs, vinegar... Grinding habit is only secondary.

• Do you have any of these habits?
• How old are you?
• And do you have any Xrays (bitewings) so I can see other teeth?

 

[David L.]

That is a typical erosion lesion, caused primarily by the intake of acidic foods and drinks, e.g. soft drinks, sports drinks, citrus fruits and drinks, chewable Vit C tabs, vinegar... Grinding habit is only secondary.

• Do you have any of these habits?
• How old are you?
• And do you have any Xrays (bitewings) so I can see other teeth?

Hello and thank you. I'm 40. X-rays attached.

I drank soda and ate candy regularly in my teens and twenties, but I've never had issues with my teeth other than a couple of cavities. I did buy an electric toothbrush a few years ago after the hygienist said my mouth showed signs of acidity. My diet is clean (post-workout sports drink, occasional citrus fruits). I floss and brush daily. This is the most worn tooth in my mouth.

The tooth has dull ached before. It usually goes away after a few days, week. I assumed it was caused by grinding harder than usual (I wear a custom guard). This time the ache has persisted for over a month. The dentist says the enamel is gone from the chewing surface. He says filling could cause fracture. Also, continued grinding could cause fracture. He is recommending a zirconia, ceramic crown.

 

[MattKW]

Thank you for the info and pics.

1. Once you lose enamel, the teeth start getting sensitive. Yours are not the worst I've seen for a 40yo, but you're still only 1/2-way through your life. Also, it appears as if your front teeth have started chipping.
2. If you still have a post-workout drink, at least rinse your mouth afterwards, and allow 30 mins for saliva to reach protective levels again. Really, I'd prefer you skipped sports drinks altogether (see attached). Also read conclusion to this.
3. If you're eating citrus for the Vit C, then changing to bell peppers (capsicum), strawberries, tomatoes, cruciferous vegetables (broccoli, brussels sprouts, cabbage, cauliflower), or white potatoes will meet daily requirements.
4. The cupping on that molar is moderate. It might be simply covered with composite. If there's not enough retention, then some minor drilling might be needed. At your age the pulp ("nerve") has receded enough to allow this.
5. A crown is way overkill. Just drilling for a crown would potentially disturb the tooth much more than a small filling, and about 5% of crowned teeth need follow-up RCT due to such damage.
6. IF... you did do a crown, then gold is the most conservative technique, and also the most tooth-friendly for the opposing tooth to chew. Prepping for zirconia is very destructive, and personally I think they are vastly over-rated.

 

[David L.]

Thank you for the info and pics.

1. Once you lose enamel, the teeth start getting sensitive. Yours are not the worst I've seen for a 40yo, but you're still only 1/2-way through your life. Also, it appears as if your front teeth have started chipping.
2. If you still have a post-workout drink, at least rinse your mouth afterwards, and allow 30 mins for saliva to reach protective levels again. Really, I'd prefer you skipped sports drinks altogether (see attached). Also read conclusion to this.
3. If you're eating citrus for the Vit C, then changing to bell peppers (capsicum), strawberries, tomatoes, cruciferous vegetables (broccoli, brussels sprouts, cabbage, cauliflower), or white potatoes will meet daily requirements.
4. The cupping on that molar is moderate. It might be simply covered with composite. If there's not enough retention, then some minor drilling might be needed. At your age the pulp ("nerve") has receded enough to allow this.
5. A crown is way overkill. Just drilling for a crown would potentially disturb the tooth much more than a small filling, and about 5% of crowned teeth need follow-up RCT due to such damage.
6. IF... you did do a crown, then gold is the most conservative technique, and also the most tooth-friendly for the opposing tooth to chew. Prepping for zirconia is very destructive, and personally I think they are vastly over-rated.

Thank you, @MattKW. I appreciate this information and your help.

I will consult another local dentist about this issue and the potential of composite. You mention the possibility of "minor drilling" - would that be an onlay?

Also, out of curiosity, I asked the dentist if a zirconia/ceramic crown could eventually be replaced by a gold crown. His response was, "Yes, the gold crown would just have to be thicker to accommodate the zirconia/ceramic prep." Is that true? Could a tooth that has been prepped for a zirconia/ceramic crown someday support a gold crown?

Thanks again.

 

[MattKW]

• Minor drilling - I mean making the existing cupped-out lesion a bit deeper and squarer for a normal small composite filling.
• The dentist told an inaccurate statement. A gold crown prep is the most minimal thickness of any dental crown material. Monolithic zirconia (solid zirconia) requires slightly more drilling. Layered zirconia (zirconia with a layer of porcelain) or full porcelain requires more thickness again; and is liable to chipping. Porcelain-fused-to-metal is similar to layered zirc (attached 1 with my annotations).
• Also, gold is gentler to the opposing teeth when chewing, and zirconia is not advised in bruxers (attached 2).

 

[David L.]

@MattKW, it's very kind of you to help people this way. Thank you.

 

[Goldzircstein]

@MattKW , If a gold prep is the most minimal thickness, would that preclude a gold crown from being modified to go on a tooth that has received a pfm or zirconia prep?

 

[MattKW]

No, you could place a gold crown on one that had been prepped for PFM or zirconia. The gold could be a bit thicker than necessary, so it would simply cost you more.

 

[Goldzircstein]

Good to know, thanks for responding.

 

[Goldzircstein]

How much metal would typically go into a crown for a molar? Is there a way of figuring out what the lab fees for a gold crown would be? There are dental fee guidelines in some places but sometimes they say " + Lab " w/o specifying how much that part would normally cost.

 

[MattKW]

It would depend upon the quality of the gold alloy (preferably high precious) and the amount required (per gram). Unfortunately, the lab wouldn't be able to give an exact quote on the amount required until they had an impression of your prepared tooth and could see how much was required. However, they might be able to give you a range of usual costs.
Most people want yellow high precious (yellow gold); my lab used Bego PontoLloyd G at 84.4% Au (see attached). You can see that in this brand, white high precious kicks in when the gold content drops below 80% Au. To qualify as a high precious there must be 60% noble metal, of which more than 40% must be gold.
For a very good layperson overview of dental alloys, go to here.

 

[Goldzircstein]

Hello again, and thank you for your invaluable assistance. I've heard that many dentists in North America use labs that are in far away Asian countries so as to be able to make more profit on the crown. The profit part doesn't really bother me but is there any way to be certain of the quality control? Are the dental prosthetics labs regulated with transparent oversight? Does the dentist and/or patient have a means of verifying that the crown is made of what it is supposed to be made of?

 

[MattKW]

Ask your dentist if they use a local lab. Ask to see the itemised invoice if you want to check on the gold alloy used.