Thursday, 16 July 2015

Cosmetic Veneers - Aspire Dental Academy Part 2

So here is part 2 of my days with Aspire Dental Academy following my first post about composite (click here to go to the post). This post will focus on veneers in dentistry.

Some of my Practise Veneer Preparations

40% of medico-legal world is down to patients who are unhappy with their veneers - but if a patients asks you how long a veneer lasts, what would you say? 

According to studies, veneers have a failure rate of 3% per year (mostly down to debonding), however, success rate is related to aesthetic outcome for the patient i.e. are they happy with the way the veneers look?

Aims of Veneer Treatment

  1. Ensure the veneers look aesthetic - refer to the pink and white aesthetic score (i.e. teeth and gums)
  2. Ensure the veneers do not come off

When offering veneers as a treatment option, you must make sure there is NO inflammation as this will lead to bleeding when you place retraction cord. Apart from excellent oral hygiene, you can also recommend using Chlorhexidine 3 days before the patient is booked in for their preparation appointment. 


Planning Stage

This is the most important and difficult stage of the process of veneers and you must take your time with this. Here are some things you need to take into account:

1. Patient Expectations

What is the current situation like? If it's the colour they're unhappy with then why don't you consider whitening? If it's the alignment, consider orthodontics? And if it's the shape, you could consider composite bonding

How does the patient perceive their problem and what is their desired outcome? To help you consider what treatment is necessary, use the principles of Smile Design (see my previous post about this). 

After you've decided if veneers are appropriate for the patient then you should consider what material to choose: this could be composite, porcelain or Emax

2. Shade assessment

This is something that a lot of dentists are not confident in taking. Remember that the strongest chroma is at the cervical edge. 

If you're unsure, take clinical photographs: pre-operative with calibrated shade tabs and also when you've prepped the tooth.

To see more about shade taking, see my recent post here

3. Soft tissue assessment

  • Gingival aesthetics (height, asymmetry)
  • Gingival disease
  • Gingival biotype (thin, thick or mixed. Thin types are more prone to recession)
  • Biological width
Bear in mind that if you place veneers in a patient with a thin biotype, their gingiva will eventually receed and expose the margins of the veneers.

Avoid placing the margin of the veneers in the junctional epithelium or connective tissue as this will lead to inflammation and recession. Make sure you place the margin slightly sub-gingival (0.5-1mm) and therefore leave 2.5-3mm between the margin and the osseous crest.  

A good tip to help you place the margin in the right place is to draw the gingival margin on the tooth then when you place the retraction cord it will retract around 0.5-1mm so use a William's probe to measure the appropriate distance. 

Note that the most common cause of inflammation around margins of veneers and crowns is not encroachment of biological width but actually excess cement left in situ. Use Loupes on high magnification and remove excess with a scalpel and ultrasonic scaler. 

If you do think that the inflammation is due to encroachment on biological width, remove the veneers and place temporaries. If that doesn't work, refer to a periodontist to removal of the inflamed tissue and reconstruction of the biological width. 

4. Occlusion

Most debonds are not caused by interferences with occlusion but actually poor cementation. Nevertheless, you need to check a patient's occlusion carefully - namely are they canine guided or group function and also protrusive movements. Teeth are designed to be loaded axially, not laterally, so if you introduce a lateral interference, restorations will fail - to read more about occlusion see my previous post here


Preparation Stage

What should you send to the lab?

  1. Photographs (pre-op with shade tabs, preps)
  2. Smile design results and changes
  3. Upper and lower silicone impressions (these can be used to make bleaching trays if appropriate but also diagnostic wax ups if you are changing the size and shape of the teeth)

Preparation

  • Prepare in 3 planes: incisal, mid-buccal and cervical
  • Prepare 0.5-0.7mm
  • Use a depth cutter in the 3 planes and draw in these on the tooth to help guide up (as I have done in the picture above)
  • Decide which incisal preparation you want: usually either feathered edge or butt joint (window and overlap are rarely used)
  • A butt joint should only be used if you want to achieve incisal edge characteristics e.g. opalescents, mammelons etc. (1mm should be removed)
  • You should not break the contacts unless: there is mild crowding, the teeth are rotated or you want to change the inclination of the teeth
  • If you do break contacts, be careful in patients who have had orthodontic treatment as the teeth may move!
  • Carry out Immediate Dentine Sealing (IDS). You should try to stay in enamel but in older patients, this may not be possible. 
  • If you are removing old porcelain veneers, use Loupes and use etch to help identify areas where porcelain in still present

Temporisation


If you are providing multiple preparations, use your diagnostic wax up to make a putty matrix and a composite based temporary material (such as QuickTemp), but don't take the temporaries off the teeth once they are set. Tidy up with a bur and relieve interproximally so a Tepe can get between. This means all the temporaries are joined together.

If you are preparing a single tooth, spot etch and bond the temporary to the tooth. 

To improve the appearance of the temporary, use the correct shade and place a glaze over the top. 

Try-in and Cementation


Always ask your patients to bring a family member for the fit appointment - they're the ones who will have to look at the result and will help the patient decide if they are happy with the result.
  1. Administer local anaesthetic
  2. Remove temporaries
  3. Clean with ultrasonic
  4. Place retraction cord
  5. Wash and dry the tooth
  6. Set up veneers in the correct order, load with clear try-in paste and place on dry teeth
  7. Check fit and occlusion and approve aesthetics with patient (tell them to be careful when sitting up!)
  8. If everything is ok, proceed to cementation!
  9. Place rubber dam
  10. Wash the try-in paste away then dry
  11. Prepare the veneer: wash, dry, scrub with hydrofluoric acid for 90 seconds, rinse then place 2 coats of silane
  12. Sandblast the tooth, etch then prime and bond separately
  13. Place veneer, remove excess cement with tepes, floss and with a microbrush which has bond on it
  14. If you have a rubber ultrasonic tip, use this to vibrate the veneer further into place, remove any more excess cement with a scalpel, then cure
  15. After your first round of cure, place glycerine and then cure again to prevent marginal staining
  16. Remove cord and remove any excess with a scalpel and ultrasonic scaler
Use a clear-try in paste as your technician would have compensated for any discolouration when making the veneers (as long as you've sent photographs!).

The big question: which cement should you use? The best ones to use are light cure resin cements such as Nexus, Variolink or Calibra


Thanks again to Raheel and Ahmed for a really interesting couple of days the hands on elements were fantastic! I know feel more confident in offering cosmetic composites and veneers for my patients.

Do you provide veneers in practice? Let me know what you think in the comments below!


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