Digital Crowns

Penrith, Cumbria. Friday 22-August-2025.

The dental industry has significantly changed since I last had a crown a decade ago. The transition from analogue to digital is amazing. Using CAD/CAM techniques the process of designing and manufacturing crowns has been transformed.

Back then an impression was taken using something resembling a stainless steel horseshoe filled with plasticine stuffed into your mouth. Suppressing the gag reflex was areal challenge. This was done twice: once for the prepared crown and the other for the opposing bite. Those were sent away and positives cast for the dental technician to craft a crown that fit the stump and met precisely with the opposing teeth. See Two titanium implants conclusion for an example.  That could take weeks or a couple of months. The second visit was for the fitting and fine adjustments to the bite.

Now the dentist creates a 3D image using a camera wand that takes what must be hundreds of images judging by the amount of clicking. The wand has an orientation detector and some amazing software uses this information to stitch together a 3D image.

Repeating this with the opposing teeth and a clenched jaw scan creates an image with the bite contours shown in colour. Now I am seriously impressed.

The software the suggests a crown design based on all the above. The dentist then tweaks the design on the screen to get the best mechanical and aesthetic result.

When they are happy with the design, they send it to the room next door where an automated lathe is loaded with a blank cube of zirconium dioxide.

The CNC (Computer Numerical Control) lathe then does it stuff and turns the little cube into a crown ready to be fitted.

The final fitting is done with a bit more tweaking. The crown is then cemented in place and the final adjustments done with articulating paper and some delicate grinding. You then walk out with a new crown prepped, manufactured and fitted all done in a couple of hours.

https://www.dentsplysirona.com/en

Crown Failure and Extraction UL7

Penrith, Cumbria. Wednesday 14-June-2023.

While we were in Italy one of my crowns started to wobble and then fell off completely. Fortunately we were due to return to the UK the following week and my dental practice was able to squeeze in an emergency appointment. 

My teeth happen to be well documented because my longtime dentist Professor Raj K Raja Rayan OBE, now retired, was also a dental lecturer. One time I went for a visit and my x-rays were on the board with a big letter A. It turned out that he had used them as an exam question and asked the candidates what their assessment and treatment might be. One wag joked, “I’d pull them all out and start again!”

He also used my teeth in a presentation on crowns, which is how I came to know the dates of every single crown in my head. This one was UL7, the gold crown top left (right in photo) at the back fitted in 1994.

When I got to the dentist it was obvious that it was going to be an extraction, which I was not looking forward to, as there was nothing left above gum level. However the dentist did a wonderful job. He trisected the tooth and extracted each root separately, so it all went very smoothly. 

I showed him this picture of my teeth complete with dates, including the fact that this crown was nearly 30 years old. “That’s older than me!” he exclaimed. So it’s not just policeman who are getting younger.

 

Titanium Implants No's 6 and 7

A long time in the planning. Upper left 4 and 5 have been on the endangered list for over two decades; since 1991 to be exact when UL5 was crowned.

UL4 went a long time ago and UL5 was fitted with a cantilevered crown to help bridge the gap. That clearly puts strain on the root as there is a rotational component.

Note also the two dots at the top of the roots. They are little pieces of silver from root canal work I had done in the late 1970's under a general anaesthetic in John Radcliffe Hospital, Oxford.

Eventually, earlier this year, the root cracked under the strain and had to be extracted. The game plan had always been two implants when the inevitable happened.

There was a wait of three months to let the site heal and allow for some bone regrowth. Once the wait was over the implants went in under sedation, as with all previous implants. Another period of healing for osseointegration where the bone and metal bond.

The next stage is to cut through the newly re-grown flesh and bone to extract the temporary, stainless steel, centre screws. Then the posts (or impression copings as they are correctly termed) were, temporarily, inserted for the taking of impressions and casts.

They are replaced with "mushrooms" around which a more shaped gum will form while the casts are sent off for the lab work of making the crowns.

Finally the grand finale: remove the "mushrooms" and fit the abutments (special screws that have a special shaped head which support the crowns) and crowns. Rash declared himself happy with the result.

It still feels a little odd with teeth filling the hole that my tongue has got used to over the last six months but that will pass. I am pleased that I will still be able to chew my steak when I am 103. A wise investment.

Two titanium implants conclusion

Part two of the implants - a return visit to fit the crowns.

This finally fixes a gap that has been there since 1989 when a previous dentist made butchery of an extraction of the lower right 7 molar. It was that extraction that sent me to Harley Street in search of the best dentist I could find. As a consequence I have invested in some fine dental work in the intervening years.

The eventual failure of the lower right 6 molar meant it was time for implants to fill the gap. I am sure that implant practice will have improved in the intervening decades so the wait was probably beneficial.

The previous visit involved taking accurate casts with the temporary "golf tees" replaced by the pegs that would provide the final support.  Casts and pegs went off to the dental laboratory for construction of the new crowns.

The new crowns in place on the cast:

An X-ray with the new crowns installed. I was pleased to note that screwing the pegs into the implants used a torque wrench so that there was no danger of over-tightening.

The crowns had to be cemented into place in the correct sequence because the angles meant the 7 had to go in before the 6 otherwise they wouldn't fit.

Plan view of the new crowns. The fit was micron perfect. I can tell by the way the upper and lower teeth all meet simultaneously when I put my teeth together - like Swiss engineering.

It still feels odd eating on the right hand side. I am having to make a conscious effort to chew on that side; I am sure normal eating will soon be resumed.

Dental Implant Number 3

An extraction, an implant, a bone graft and two stitches.

This tooth goes back to pre-1993 when I foolishly tried to tighten the knot in a black bin bag using my teeth. The upper left incisor snapped off at gum level. Ouch! you may say. Fortunately I felt nothing at the tooth was dead and hence brittle.

The solution was a post and crown which lasted until 2007 when it fell out and had to be replaced.

That replacement lasted until last month when I made an emergency trip to the dentist yesterday with a wobbly incisor. The crown and post popped out easily because the root was cracked. Doubleplusungood. So I booked in for an extraction and an unplanned implant. Nothing showing above the gum so the extraction could be tricky.

As it turned out the extraction was straightforward - not that I could tell as I was sedated. Then the operation preceded with the cleaning out of the canal and drilling and inserting the implant. The sedation was starting to wear off so I was aware of the disconcerting sound of hammering as the plug was tapped into place - eew!

The bone on the facial side of the implant needed a little building up so to encourage bone growth, in preference to gum, Rash put in some bone biomass and a collagen membrane (more about Bio-Oss and Bio-Gide). The biomass acts as a framework for bone regeneration and the collagen provides a protective membrane.

I now have to wait a couple of months for bone regrowth before the implant surroundings are firm enough to take the strain of the post and crown. Until then I can either have a gap or install a mono-toothed plate. That makes me feel like I'm lisping and is purely cosmetic so I will save it for "best".

Two titanium implants

You can tell when someone takes a pride in their work by the way they talk about the task in hand. My work-in-progress implants involved careful planning and preparation by my dentist, Dr Rash Patel, to make sure all goes well.

I have a large gap from previous extraction of a molar (back in 1989 and that is another story). Then, eventually, the tooth next to the gap (labelled X) gave way. That meant I was going to have a two-tooth gap - too wide for a bridge so implants was the answer. In some ways it was a bit of a repeat of the two previous implants - see An extraction and two posts.

Rash very carefully extracted the tooth by bisecting the crown and extracting the two roots separately. That way the bone between the roots remained undisturbed and maximised the bone regrowth where the planned implant would go. That needed six months healing but in the end it was nearer to a year before I went back.

I went back for a proper three dimensional CT scan to check bone density, location of the nerve and positioning of proposed implants. Casts were taken and implants prepared for the procedure

The actual implant installation was done under sedation and all seemed to go very well. I was under for two hours and Mary was the "responsible adult" who came to escort me home as required after sedation. I knew nothing as I was "away with the faeries".

The after effects were minimal: I took a couple of paracetemol for when the anaesthetic wore off and that was it. No painkillers needed the next morning, no bruising, minimal swelling that subsided in a couple of days. A tribute to Rash's skill.

A couple of weeks later I went back to have the stitches out. Next up a fresh impression, and then the actual crowns. In March the things that look like golf tees will be replaced by two new crowns and I will be able to eat properly on the right side of my mouth for the first time in over a year. Om nom nom.

Upper left six molar - doubleplusungood

Adding to my collection of dental x-rays and not in a good way. A couple of weeks back one tooth felt a bit loose but thinking it was possibly a bit of gum inflammation I was assiduous in my dental hygiene and it seemed to improve. But then it got worse and a trip to Harley Street was quickly arranged.

Raj was away but his oppo, Lawrence, did the honours with an x-ray and the bad news. One of the roots under the crown had broken off and gone septic - now lying at a jaunty angle (to the left of the x-ray).


Upper left six molar with broken root

So it is a week on the Amoxicillin followed by a surgical extraction. Not something to look forward to - doubleplusungood.

Long time no blog

This is going to be to have to be a bit of a Portmanteau blog as it has been *shock, horror* over two weeks since I last put finger to keyboard...

Changing jobs: After four years and many contract extensions (I must have been doing something right) I finally left the client for whom I have been working since August '04. Odd feeling as it is the longest I have ever worked on any project, ever. Fortunately (in this current climate) I have picked up a new contract with one of the recipients of my former client's offerings - a veritable case of poacher turned gamekeeper.

My double crown fell off: A quick trip to Raj to have it temp-bonded back on revealed that the bone of the jaw underneath had healed so well that it had pushed up against the crown from below and eased it off the implants. So he got the technician to grind some porcelain off the underside of the bridge and popped it back on. It shows the wisdom of Raj using temporary cement - a deliberately designed point of failure to prevent stresses building up where they shouldn't.

Weekend in Scotland: Visiting the MIL as per usual. An opportunity to see Mary's sister and family as well as spend time with her Mum. This weekend Mary decided to kitchen cupboards needed a good clear out. Yellowing plastic containers out of the Ark and tins with a 'best before' date in the last century.

A week at home between contracts: Though not idle - I wish. General tidying and foutering and a visit to my Mum and Dad on Wednesday. Oh yes, and I painted the breakfast room and kitchen in my spare time.

Triple Crown settling in

It is eight months since my implant and I went back to Ashok last week for a check-up. The hole left by the extraction has filled in with bone as has the dodgy area to the right of the right-hand post.


Post and crowns - eight months later

The whole thing is made to amazingly fine tolerances, measured in microns. The posts have to be exactly parallel so the two ends of the "Siamese" crown can slide on. Compare the above with the before. The dark area is the part that has healed nicely thank you.


Posts and temporary crown - just after operation

Call me Count Dracula

So it was back to Dr Ashok Sethi to have the stitches out and not before time. After 10 days my gums were telling me the stitches had done their job and were now more of a hindrance than a help.



X-ray of whole mouthful of teeth showing implants

I do not remember these X-rays being taken although I must have been led from the chair to the machine and back again. What I do remember is Ashok saying "Wider, Wider!" and me saying "Ow!"

It appears that, to be very sure of avoiding the nerve, he exposed it so he knew exactly where it was. This would explain why I felt some discomfort even through the anaesthetic and the sedative. talk about touching a raw nerve. Ugh and shudder.



X-ray of lower left teeth after implants

That it is for three months when I go back to get the OK for the permanent crowns to replace the current temporaries. Well apart that is from crowning the lower right 8 but Raj cannot take an impression for a least six weeks till these chaps have bonded in.

An extraction and two posts

Well that wasn't as painful as I was expecting but that was mainly because I was doped up to the eyeballs. The extraction of the molar was the part I was least looking forward to. The work was done under a local but I was also sedated with a drip feed into the arm. I don't know what was in there but three hours of my life disappeared down a chemical black hole.

When I came to Dad was there as the "responsible adult" to make sure I got home safely. I had an hour's kip, we strolled down to the chemist to pick up a prescription for antibiotics, then - duty discharged - Dad went back to Farnham. When the anaesthetic wore off it was not too painful, no need for more paracetamol this morning. Now it is a soft diet for three months while the bone grows in and bonds to the implants.


CT scan of jaw showing site of implants

This is the CT scan I had done last week with the implants superimposed. The yellow is the implant and the green is the post that takes the crown. Number 36 is where the cantelivered crown was. Number 37 is where the extraction was and had to move close to the adjacent tooth because of the hole left by the split root. That will fill with bone over the next few months - the human body is a wonderful thing!

CT Scan for Titanium Implants

Tuesday I went for a CT scan in preparation for a couple of titanium implants next Thursday. I swear I could feel the scan move down my head. The technicians said no-one had mentioned that before but I could feel a planar circular sensation rotating round and round and passing down my skull, most odd feeling!

Some while back I mentioned that I had 11 crowns (including 3 post and core) [1]. Here is the proof courtesy of the implant specialist Dr Ashok Sethi:



X-ray of whole mouthful of teeth

Below is the lower right 8 (on the left of the X-ray) that gave me such grief a while back [2]. But there will be no implant there. Raj will crown it and then wait till, one day, it eventually fails and then do two implants together.



X-ray of lower right teeth (8 & missing 7)

No, the implants will be where I had the extraction last October [3]. The extraction was tricky because I had a "siamese" crown. The lower left 6 only had one root; the tooth having cracked the other root had to go. Half a root wasn't enough to take the strain of a crown so Raj crowned the two as a pair. See diagram below.


Diagram of lower left teeth (6 & 7)

Eventually the other half root went and so it took had to be extracted *from under the crown*. That meant separating the root from the cantilevered crown then easing the root out sideways - not as bad as it sounds. Now the extra strain on the remaining tooth has caused its root to crack so that too will have to go and two implants go in their place.



X-ray of lower left teeth

Can you feel anything when I do this? (2)

Apologies to both my readers, I have been off air for a few days 'cos my brain has been all of a jangle with toothache.

Last Monday I went to Raj as a follow up visit to a new crown and an extraction a couple of weeks ago. One tooth on the other side was giving me some grief and it can be hard to tell exactly which one. The nerves run close together and may cause a different tooth to appear to be the origin. So he sent me round to the endodontist for a second opinion and he pinpointed the lower right 8 (back molar).

Wednesday the endodontist did a full root canal job and sent me home. In his letter to Raj he wrote, "Healing is expected to be uneventful." Hah! If you consider "writhing on the living room carpet at two in the morning in a foetal ball in excruciating pain chanting over and over the mantra 'f*** that hurts, f*** that hurts, f*** that hurts'" as uneventful then yes it was.

I do not *ever* want to feel pain like that again.

Even the extra painkillers from the doctors could not mask the pain so Saturday night (well actually Sunday morning as it was half past midnight) I cracked and phoned Raj. He did a mercy dash to his surgery in Harley Street and I fell out of a taxi a few minutes later. He did some magic scraping with a steel implement and said that should do it. He was off to Sri Lanka on Sunday so he gave me a copy of my X-Rays in case I needed to go to A&E.

I am glad to say the pain and the swelling is slowly subsiding, the antibiotics and my immune system are slowly repairing that damage; soup for breakfast and lunch was getting tedious. I still cannot open my mouth more than half an inch, I have to post food in horizontally in thin slices, but that too will pass.

And then of course I can have the thing crowned! But I think I will wait a while until the memory fades.

PS
Deep gratitude is owed not only to Raj but also to his daughter, a doctor, who lives nearby and who he dragged along. Apparently I was slurring my words and he was concerned so wanted some medical backup.

He looks in my mouth and then he starts to gloat

He says my teeth are OK but my gums got to go. *

Went to Raj on Friday because my teeth were giving me gyp and it looks like I am down for two crowns and an extraction at Harley Street prices. The latter may be years off but the crowns, numbers 12 and 13, are to be done as soon as I get the x-rays taken (see previously "And finally monsieur a wafer-thin mint").

Meanwhile I am on Corsodyl mouthwash, for the gingivitis. Corsodyl is one of the viler tastes on the planet and wreaks havoc with the taste buds. My tongue feels like it has been lightly sand-papered. I can forget about drinking fine wines until I am off the stuff as everything has hints of sand and glue.

* Unfinished Sweet by Alice Cooper

And finally, monsieur, a wafer-thin mint

Well it was a busy day yesterday.

First port of call was Eastleigh and our accountants Langdowns DFK to sign the forms making Mary a fully-fledged director of M&M Enterprises thus turning it from Mark&McLellan to Mark&Mary. Not that we are exactly a major multi-national corporation, more what the Americans call a "Mom and Pop operation". Still it is worth being a company for tax efficiency reasons.

Second port of call was London and the Oral Hygiene Centre in Devonshire Place for a full set of "after" X-rays. The "before" set was taken fifteen years ago when I first starting seeing Raj Rayan. Now, many root canal treatments and eleven - count'em, eleven - crowns later he felt it was time for an "after" set. Each crown was carefully colour-matched to the existing teeth which means they are all the same old not-as-white-as-I-would-like colour. But they are structurally sound, all mine and paid for!

Third port of call was Charlotte Street to meet up with Pete and Amanda for drinks then across the road to Fino, Tapas restaurant. The food was excellent but not cheap. One high spot was the presence of Pedro Ximenes, PX to it's friends, on the wine list - like liquid Christmas pudding. This was recommended as an accompaniment for ice-cream and is what we would have taken to Bob and Lynn's on Saturday if we had had any. So this was a chance to try it and I just had to have the Chocolate Brownie with pistachio ice-cream. Mind you it was struggle, I felt like Mr Creosote by the end.