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23/09/2013

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Minimally invasive dentistry:

A series of lectures

Everyday practice should be built on this

foundation

AKA

Does size matter? University of Birmingham Masters in AGDP

Part 1

…first, a few principles for the

lectures

Eastbourne, The Dental Practice Board

Board of Dental Practice Board, 1988

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The database

Over 500,000 restorations at the Dental

Practice Board, Eastbourne, Sussex,

11 years’ duration

Modified version of Kaplan-Meier

methodology used to plot survival curves

for different sub-groups

Dr.Steve Lucarotti

Direct placement

restorations Influence of patient factors

Influence of patient age

Influence of dentist factors

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Do young dentists make better fillings

than old dentists?

Influence of dentist age

Influence of dentist’s sex

Single pontic bridges • A total of 2,162 single pontic bridges

(excluding resin-retained bridges) were

identified in the data over a period of

eleven years.

• 2,035 porcelain bonded to gold

• Mostly on upper jaw, except 1st molars

Survival of bridge retainers:overall

Overall survival at 10 years:72%

0.5

0.6

0.7

0.8

0.9

1.0

0 1 2 3 4 5 6 7 8 9 10

Time in years from placement to re-intervention

Pro

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…and last…

Influence of cavity design

Eleven Year Survival - by Treatment Code

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1.0

0 500 1,000 1,500 2,000 2,500 3,000 3,500 4,000

Time in days from placement to reintervention

Pro

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Overall

Single surface amalgam

Two surface amalgam, not MO or DO

MO or DO amalgam

MOD amalgam

Resin composite

Tunnel amalgam

Glass ionomer

Root filling + indirect restoration

Large cavities have poorer survival than small

Take home message Nothing lasts forever:

Size matters – big fillings last less

well than small

Take home message Keeping cavities as small as possible

is therefore important

nothing lasts forever

2 Humans by era Average lifespan at birth

Upper paleolithic 33

Neolithic 20

Bronze age &Iron age 35+

Classical Greek 28

Classical Roman 28

Pre-Columbian N American 25-30

Medieval Islamic Caliphate 35+

Medieval Britain 30

Early modern Britain 40+

Early 20th Century 30-45

Current world average 67.2

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Humans by era Average lifespan at birth

Upper paleolithic 33

Neolithic 20

Bronze age &Iron age 35+

Classical Greek 28

Classical Roman 28

Pre-Columbian N American 25-30

Medieval Islamic Caliphate 35+

Medieval Britain 30

Early modern Britain 40+

Early 20th Century 30-45

Current world average 67.2

Life expectancy at birth, 2008, (years)

over 80

over 75

over 70

67 to 70

60 to 67

50 to 60

45 to 50

40 to 45

under 40

Source:

Wikipedia

Life expectancy in industrialised

countries now 80 years

Therefore mean restoration longevity

must be 73 years!

Walter Breuning, age 113 years

All restorations are temporary,

except for the last one!

Message:

Start the restoration cycle as late as

possible (primary prevention)

Keep as much sound tooth structure as

possible (adhesion)

Increase the longevity of every

restoration as much as possible

(perfect seal and maintenance of

restoration)

Longevity of hip joint prosthesis = 15 years

nothing lasts forever

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More important now than ever!!`

“The day is surely coming when

we will be practising

preventive rather than

reparative dentistry,

GV Black, 1896

3

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“The day is surely coming when

we will be practising

preventive rather than

reparative dentistry,

when we will so understand

the etiology and pathology

of dental caries that we will be

able to combat its

destructive effects by

systemic medication”

Does size matter? Minimally invasive dentistry

….aka

A definition

“Minimal intervention dentistry is a

philosophy of professional care

concerned with the first occurrence,

earliest detection and earliest

possible cure of disease, followed by

minimally-invasive and patient-

friendly treatment to repair

irreversible damage caused by such

disease” Tyas MJ, Anusavice KJ, Frencken JE, Mount GJ. Minimal intervention

dentistry – a review. FDI Commission Project 1-97. Int.Dent.J.2000:50:1-

12.

First mention: Mount GJ. Minimal treatment of

the carious lesion. Int.Dent.J.1991:41:55-59

…another mention! Extension for prevention was

taught as recently as 1983

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Three principles for MID

Early caries detection

& caries risk assessment

Remineralisation of demineralised

enamel & dentine

Optimal caries preventive measures

Only when these have failed and a cavity

has developed should a minimally invasive

operative intervention be undertaken

Does size matter?:Objectives

Which bonding agents work best in which

situation?

How to minimise stress in posterior

composite restorations and suggest a

minimal cavity design

How to repair worn anterior teeth using

resin composite

Preparation depth matters for veneers

Does size matter?:Aims

To illustrate the potential for injury

to the pulp during operative intervention

To demonstrate that large restorations

provide poorer longevity than small

To suggest some minimal intervention

methods of treatment

Does size matter?:Aims

To demonstrate that large restorations

provide poorer longevity than small

Does size

matter?

Does drilling and

filling affect teeth?

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Dentine/pulp reactions to full crown procedures Dahl BJ, J.Oral Rehabil.1977:4:247-254

Severe acute pulp reactions were observed

subjacent to the dentinal tubules cut in full

crown preparation

Tooth preparation and pulp degeneration Christensen GJ. JADA 1997:128:353-354

Factors associated with pulp

degeneration include:

•Use of worn out diamonds and burs

•Improper cutting techniques (heavy

cutting loads)

•Excessive preparation depths

•Inadequate water coolant

•Over-drying tooth preparation

•Exothermic chemical reactions

of provisional materials

Tooth preparation and pulp degeneration Christensen GJ. JADA 1997:128:353-354

CONCLUSION

Patients should be warned that pulpal death

and endodontic therapy can result

from crown placement

Long term effects of crown preparation on pulp vitality Felton D. et al. J.Dent.Res. Abstract 1139 High incidence of pulpal necrosis with full

coverage restorations (13.3%)

Placement of foundations resulted in

a significant increase in pulp morbidity

(18% vs 8%)

Correlation between length of temporisation

and pulp necrosis

Clinical complications in fixed prosthodontics Goodacre GJ et al. J.Prosthet.Dent.2003:90:31-41. Literature review of past 50yrs

Of 823 crowns studied, 27 needed

endodontic treatment, mean incidence

of 3%, range 0 to 6%

Pulpal evaluation of teeth

restored with fixed prostheses Jackson CR, Skidmore AE, Rice RT

J.Prosthet.Dent.1992:67:323-325

130 patients with a crown or bridge

fitted 1984-1988

603 teeth assessed in 1990

166 had already received RCT,

leaving 437 crowned while vital

5.7% required RCT during the

observation period

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Prevalence of periradicular periodontitis associated with crowned teeth in an adult Scottish subpopulation Saunders WP, Saunders EM. Brit Dent.J.1998:185:137-140

802 crowns assessed radiographically

458 vital at preparation

87 (19%) had radiographic signs of

peri-radicular disease

344 crowned teeth had previous root filling,

51% of these had peri-radicular radiolucency

Prevalence of periradicular periodontitis associated with crowned teeth in an adult Scottish subpopulation Saunders WP, Saunders EM. Brit Dent.J.1998:185:137-140.

CONCLUSION:

Pulpal damage may occur during

procedures to provide a crown

Iatrogenic injury to the pulp in dental procedures. Bergenholtz G. Int.Dent.J.1991:41:99-110.

LITERATURE REVIEW: CONCLUSIONS

Iatrogenic (“dentistogenic”) injury to the

dental pulp is not an insignificant problem

in clinical dentistry

Pulpal necrosis occurs with a frequency of

10-15% over a period of 5-10 years

Take home message

Drilling isn’t great!

……for teeth

A basic principle:

Minimally invasive methods

of treatment should be

employed where possible

…therefore

% of teeth damaged by dentists

0

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% of teeth damaged by dentists

!

Root perforations

Following hemisection in which the unreparable

mesial half of the root was removed, iatrogenic

damage can be seen on the distal surface of LL5

Does cutting Class II cavities cause

damage to adjacent teeth?

YES!!!

Cardwell JE, Roberts BJ. Damage to adjacent

teeth during cavity preparation?

J.Dent.Res.1972::51:1269-1270.

Long TD.

J.Dent.Res.1980:59(Spec.Issue):1799.

Elderton RJ. Positive dental prevention.

London, Heinemann Medical Books, 1987:57-95.

Progression of approximal caries in relation

to iatrogenic preparation damage

Qvist V, Johannessen L, Bruun M

J.Dent.Res.1992:71:1370-1373

77 dentists from Public Dental Health Service

in Denmark

Die-stone models of 187 new Class II cavities

Examined with stereomicroscope

Damage found on 66% of adjacent surfaces

Teeth followed for 7 years




J.Dent.Res.1992:71:1370-1373

RESULTS

Operative treatment needed on 10% of

undamaged surfaces

Operative treatment needed on 35% of

damaged surfaces (p<0.05)

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J.Dent.Res.1992:71:1370-1373

CONCLUSION

Iatrogenic preparation damage is a frequent

side-effect of operative intervention with

approximal caries lesions…the damage

increases caries progression and need for

restorative treatment of the adjacent teeth.




J.Dent.Res.1992:71:1370-1373

CONCLUSION

Danish dentists damage teeth!!!

Does size matter? ….regarding crowns

Tooth structure removal for various

preparation designs for anterior teeth Edelhoff D, Sorensen JA. J.Prosthet.Dent.2002:47:502-509



Typodont teeth

Prepared for porcelain veneers (4 variations), all-ceramic crowns (2 variations), resin-retainer, metal-ceramic crown

10 preparations per group, by one clinician

Removed tooth structure measured by “gravimetric analysis”



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CONCLUSIONS:

All-ceramic and metal-ceramic

crown preparations required the

removal of 63% to 72% of the

total crown weight

Preparations for veneers and

resin-bonded prostheses removed

3% to 30% of crown weight

Tooth substance removed for a

metal-ceramic crown was 4.3 times

greater than for a ceramic veneer

Preparation for all-ceramic crowns

was 11% less invasive than for

metal-ceramic

Quantification of residual dentine

thickness Davis GJ.J.Dent.2012:40:571-576

Micro CT scans taken of extracted teeth before and

after crown preparation for metal-ceramic crown

16 extracted upper central incisor teeth

Residual dentine thickness measured

Quantification of residual dentine

thickness Davis GJ.J.Dent.2012:40:571-576

RESULTS

All but one of the prepared teeth had regions with

residual dentine thickness of 1.5mm, in 6 teeth it was

less than 1mm and in 3 it was less than 0.5mm

Is this a problem?

The residual dentine thickness following tooth

preparation has a critical influence on

subsequent pulp degeneration. Murray PE et al.

Hierarchy of pulp capping and repair activities.

Am.J.Dent.2002:15:236-243.

2mm or more of residual dentine is critical in

preventing pulp damage. Stanley HR. Dental

iatrogenesis. Int.Dent.J.1994:44:3-18.

1mm of dentine might protect the pulp from the

cytotoxic effects of zinc phosphate cement. Pameijer CH et al., Biocompatability of a glass ionomer luting

agent.. Am.J.Dent.1991:4:134-141

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Poorly

fitting

crowns

aren’t

great

either!

…while on the subject of crowns… Take home message Because of the potential for pulpal

damage or damage to adjacent teeth,

minimal or non-intervention should

always be considered

However!!!

Some patients

choose

intervention!

The effect of cavity size on tooth fracture

Literature review

tooth fracture

A common clinical problem (Braly&

Maxwell, 1981, Cavel et al., 1985)

Problem is increasing as more patients

keep their teeth longer (Liebow, 1976)

Number of cracked cusps associated

with LARGE restorations is increasing

(Fisher, 1982)

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tooth fracture: effect of cavity

dimension

Minimal cavity preparation advocated 70 years ago (Bronner, 1930, Markley, 1951)

Vale (1956) showed a decrease in the strength of a prepared tooth when cavity width increased from one quarter to one third of the isthmus width

Least susceptibility to fracture was in teeth with narrow/shallow restorations (Re et al., 1982)

tooth fracture: effect of cavity

dimension

Breaking the continuity of enamel

weakens teeth (Hood, 1990)

Narrow isthmus/deep pulpal floor

weakens teeth more than wide/shallow

preparation (Blaser et al., 1983)

A survey of cusp fractures in a

population of dental practices Fennis et al., 2002

28 clinicians in Nijmegen participated

Recorded information on cusp # for 3

months, including patient age, tooth,

size of cavity, restorative material,

cause of # etc. on a special form



238 cases of cusp # recorded

Mean age of patients = 44yrs (range 21 to 79)

No difference between mandible & maxilla

More women than men involved

Molars (79%), premolars (21%)

Maxillary molars had more buccal cusp #s

No difference in cusp # in premolars



Mastication reported as most frequent

cause of #

77% of # teeth had MOD restoration

88% had an amalgam restoration

Root filled teeth significantly more

susceptible to subgingival fracture

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Take home message Teeth with smaller fillings are more

resistant to fracture.

…in other words, size matters

Which material might be best

at preventing cusp fracture?

Another literature review!

tooth fracture: effect of

restorative material

Cusps are reinforced when a bonded composite technique is used (Morin et al., 1984, Eakle, 1985, 1986)

Composite restores strength of teeth with class I cavities to similar levels as sound teeth (Watts, et al., 1987)

Fissure sealants do not improve strength of teeth (Schultz et al., 1986)

Strength of composite-restored premolars was half of intact teeth (Reel & Mitchell, 1989)

tooth fracture: effect of

restorative material

MOD gold inlays sandblasted, tin-plated and

cemented with adhesive resin showed better

laboratory fracture resistance than MOD gold

inlays cemented with phosphate cement

(Eakle & Staninec, 1992)

Composite restorations using Superbond

DBA in wide MOD cavities improved the

fracture strength of maxillary premolars

(Sheth et al., 1988)

Take home message: Literature review indicates

that

a composite restoration

may prevent tooth fracture

does size matter? - cloud object storage | store & retrieve …€¦ · · 2013-09-23does...

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