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Anterior Tooth Preparation Course Knowledge-Base
St. George’s University Hospital, SW17 0QT Friday 4th November 2016
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How we can improve our confidence of providing predictable fixed restorations?
Within E-portfolio – you have to do crowns, perhaps a replacement conventional bridge and resin bonded
bridges
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We need to understand tooth restorability and what this needs in 2016 and beyond
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What would you and I do if this was our LL6 – would we go through this? -
Dentist-led decision-making
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Has the recent focus on direct and indirect adhesive dentistry and Dahl concept compounded our indecision
when planning conventional crowns and bridges and being confident to prepare teeth well?
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Br Dent J. 2010 Aug 28;209(4):171-4. Repair or replacement of restorations: do we accept built in obsolescence or do we improve the evidence? Sharif MO, Fedorowicz Z, Tickle M, Brunton PA.
CONCLUSION: In view of the absence of high level evidence there is a need for further well designed RCTs. To add value to the evidence base these trials should be conducted in a general practice setting which will strengthen the applicability of the research conclusions and enable dentists and patients to make informed decisions
Is it acceptable to patch / repair – or should we always replace restorations whatever their size on partial failure?
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Patch and Direct Repair (TSL) do as little damage as possible is my mantra – think of the next failure re-cycle
Patch and Repair?
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Patch and Direct Repair (TSL) Composite – is brittle so bulk it up and it will last – might need some running repairs
Patch and Repair?
3 years – Sept 2014
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DBC prep = 63% off tooth
PFM prep = 72% off tooth
PFM prep 20% > FGC prep
PFM prep x5 > Porcelain veneer (feathered) x3 > Porcelain veneer (butt joint)
We know that aesthetic restorations can come at a
biological price
Edelhoff & Sorensen (2002). Tooth structure removal associated with various preparation designs for anterior teeth. J Prosthet Dent; 87: 503-9
Edelhoff & Sorensen (2002). Tooth structure removal associated with various preparation designs for posterior teeth. Int J Periodontics Restorative Dent; 22:
241–249
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The problem is if that if you do something rarely – unless you have got ‘god-given’ talent or are lucky – when you need to do
it you will not be able to execute it well
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Blue Sky Thinking 2000 hours of repetitive skills training
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Are there other factors that worry you?
This appeared in my local paper
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Is this what we will all be reduced to?
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Conventional Retention relates to:
• Taper
• Surface Area
• Surface Roughness
Jorgensen 1955
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‘Can you remind me how long you said my crown and / or bridge would last?....’ Mrs. Angry from Purley?
I’ll just look it up!
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Survival of Fixed Space Fillers
RBBs drop down to 65% at 10 years (cf to 89.2% for FDP)
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RBB
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King et al. 2015
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Prospective outcome of 1000 consecutive RBBs in 805 patients
• Experience of Operator - Yes • Minimal preparation - Yes • Design of bridge – Yes • Replacement of existing restorations - Yes
King et al. 2015
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Failure characteristics – bond failure commonest failure
• 20% failed by 5 years • Few failed thereafter
even though more than two thirds were assessed for more than 10 years
• No failures of surviving bridges between 10 – 16 years
• As a result 5 and 10 year survival probability was 80% (as shown by survival curve)
King et al. 2015
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What is the difference?
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Median and 50% probability survival can not be calculated as survival probability greater than 80% at longest review period –
hasn’t yet dropped to 50% or below
Very odd shaped bath
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Results:
• Hazard ratio bigger for multi-abutments than for multi-pontics (the number of supporting teeth very important)
• Minimal preparation (m) more successful than intermediate (I) or maximal (m)
• Where existing restoration present in abutment teeth - placement of new restoration improves outcome compared to accepting old
King et al. 2015
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Minimal Preparation and remove and replace existing restorations within abutment tooth
King et al. 2015
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Cantilever - v - hybrid / fixed-fixed
• Difference early on
• Then both plateau off – similar survival characteristics
• Cantilever and double cantilever bridges predictable
King et al. 2015
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• Prospective
• Long-term follow up
• Butterfly bridge did very well to replace 2/2
• No median survival
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What factors will play a part in bringing lots of RBB studies together?
• Design of bridges • Type and extension of ‘wings’ • Teeth replaced • Techniques / materials / cements • Operators • Study design – duration, number, success /
failure criteria
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2013
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Results: The analysis of the studies indicated an estimation of annual failure rates per year to be: 4.6% (±1.3%, 95% CI) for metal-framed 4.1% (±2.1%, 95% CI) for fibre-reinforced 11.7% (±1.8%, 95% CI) for all-ceramic resin-bonded bridges.
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Metal frameworks
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Fibre-reinforced composite RBBs
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All-ceramic RBBs
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How would you design a best study to look at the three types of adhesive bridges?
• Prospective observation from the off
• Agreement of strict criteria of failure / success – is successful re-cementation failure?
• Randomised allocation
• Few operators / standard protocol
• Large number – power calculation
• Split mouth – design – the different bridges in the same mouth
• Long review – taking into consideration drop out
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My Cementation Protocol for RBBs
Dycal try-in – assess fit, aesthetics
and occlusion
Place retained-retraction
cord – palatal / lingual
Rubber Dam – if useful
Intra-oral sandblast
Metal wing sandblast
A/E / Prime / Bond / Lute
Cement / Oxyguard
Remove excess
cement / polish & review
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Clinical Tip: Dycal (orange) try-in to see what the abutment and pontic of the CRRB look like in-situ – can try in without it
disappearing down the oesphagus / right bronchus
Walton Dental Arts
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Clinical tip: ‘if the shade is right it will look good in ‘black and white’ if not it will look wrong’
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It does not always go as planned - back to the lab for alterations
Dycal 1
Dycal 2
Poyser and Briggs (2004)
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Dycal Re-Try-in – assess fit,
aesthetics and occlusion
Aesthetics – where opaque cement used no grey out noted – overall patient satisfaction very good (King et al 2015)
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Cementation protocol of CRBB
Place retained-retraction
cord – palatal / lingual
Rubber Dam – if useful
Intra-oral sandblast
Metal wing sandblast
A/E / Prime / Bond / Lute
Cement / Oxyguard
Remove excess
cement / polish & review
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Cementation protocol – retained retraction cord and if helpful ‘open’ rubber dam
Place retained-retraction
cord – palatal / lingual
Rubber Dam – if useful
Rubber Dam used - twice as likely to de-cement compared to no rubber dam used – less experienced operators had most failures
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A/E / Prime / Bond DBA /
Opaque Lute Cement / Oxyguard
Remove: excess
cement / retained
retraction cord /
location cast location cleat and polish &
review
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A smart and predictable solution to non-organic pain following implant treatment UR1
Walton Dental Arts
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Metal Rochette provisional RBBs are great to temporise around implants
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Creugers NH, Kayser AF. Community Dent Oral Epidemiol 1992 Oct;20(5):280-3
A method to compare cost-effectiveness of dental treatments: adhesive
bridges compared to conventional bridges.
The study shows that in the Netherlands the break even point for equal cost-effectiveness compared to conventional bridges is
achieved when the 50% survival for adhesive bridges is at approximately 6.5 yr. Clinical data indicate a higher cost-
effectiveness for anterior adhesive bridges.
Cost effectiveness – it was not possible to calculate the median 50% survival as survival at final
follow up of over 80% too high (King et al 2015)
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‘….If you do everything well – it’s very smart thinking that also buys time…..’
• Likely 10 years of survival (80% survival at 15 years King et al 2015)
• Aesthetically good
• Biologically sound
• CRRB likely to be Re-treatable
Dycal try-in – assess fit, aesthetics
and occlusion
A/E / Prime / Bond / Lute
Cement / Oxyguard
Remove excess
cement / polish & review
King et al, 2015
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RBB Audits – What DFs can do
• Identify patients who will benefit from RBBs?
• Get together as a group – Outcome of DF placed RBBs over last few year – multi-centre Audit
• Materials - Cements, Dycal, Sandblaster, Alloy, etc.
• Aesthetics & fit – remakes?
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RBBs struggle to restore molar teeth – avoid losers as you will damage natural teeth
unnecessarily
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Conventional Bridges
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3% over 23 years 20% over 3 years
Main problems • caries • endodontic • periodontal
Much Variation in Survival
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Approx 80% remain in service at 10 years
However, there are some studies that suggest a much more depressing tale
1990 2012
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Evidence Based Dentistry All as it all it seems?
Meta Analysis of 35 studies identified but only 8 could be
included in the analysis.
These 8 studies are very selective & how relevant are
they to general dental practice? Only one study from UK
(Reuter & Brose, 1984)
How relevant are these studies to us?
Scurria & Badia 1998
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Conclusions:
Scurria and Bader meta analysis (re-published in BDJ evidence based practice 1998)
75% of abutments lasted 15 years 92% 10 years Most failures mechanical (rather than biological)
Scurria & Badia 1998
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Study Provider Pts Country
Ericson UG DS Sweden
Cheung Ug/staff DS HK
Palmquist Pg/staff DS Sweden
Reuter PP PP UK
Karlsson GDP Ins Sweden
Randow GDP Ins Sweden
Valderhaug GDP DS Norway
Leempoel GDP GDP Holland
Let’s look at the 8 studies used by Scurria et al 1998 – how relevant are they to us?
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Evidence Based Dentistry - Is it all it seems?
Exclusions: Bridges of more than 8 units, those with predominantly partial coverage or cantilever design prostheses
Scurria & Badia 1998
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Evidence Based Dentistry - Is it all it seems?
Conclusions: Headline findings - less than 15% of FPD needed replacement over 10 years.
Actual results: at 10 & 15 years: 10 & 26% of FPD had been removed
13 & 31% had been removed or technically failed & replaced
4% of abutments had been lost at 10 years (but increasing fast)
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The ‘bath-tub’ curve of failure
1 2 3 4 5 6 7 8 9 10 11 12 13 14 150
10
20
30
40
50
60
70
80
% F
ailu
res
Years of Service
How long’s your bath?
Failure = Success in the USA
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Crowns and Bridges are not for life!
When they fail they will usually take one or more abutment(s), or at
best, the pulps with them
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I hope that we now have some answers for those little questions our patients throw at us when we
least expect them!
The End Thanks for your attention and I hope you all enjoy the
rest of the conference