Dental rotation period in Iraq Conservative dental department Seminar About biomimetic restorative dentistry

1. 0 | P a g e
Biomimetic
Restorative
Dentistry
‫اعداد‬
‫حكمت‬ ‫عامر‬ ‫محمد‬
‫حسين‬ ‫عويد‬ ‫حسين‬
11
/
12
/
2022
‫بإشراف‬
‫عماد‬ ‫اياد‬ ‫د‬

2. 1 | P a g e
Contents
Introduction...................................................................................................................................................5
Biomimetic Paradigms..................................................................................................................................6
Caries Removal protocols.............................................................................................................................7
- Treatment goals.........................................................................................................................................8
- Step by step tech to achieve caries end point and peripheral seal zone............................................................10
Structural analysis ......................................................................................................................................12
- How is Structural Compromise Assessed? .............................................................................................12
- What are the 4 Red Flags? ........................................................................................................................12
1) Cracks into dentin ..............................................................................................................................12
2) Isthmus width > 2 mm ........................................................................................................................12
3) Cusp thickness < 3 mm.......................................................................................................................13
4) Box depth > 4 mm..............................................................................................................................14
- The Rainey Ridge & Peripheral Rim Fractures (PRF) .............................................................................14
- Crack Propagation..............................................................................................................................15
- Managing Cracks ...............................................................................................................................15
- Crack Visualization ............................................................................................................................16
I) Visualization by Crack Dehydration..................................................................................................16
II) Visualization by use of Primer..........................................................................................................16
- Dissection of Cracks and Crack Removal Endpoints (CrRE)....................................................................16
- Occlusal Effect Caries (OEC) ..............................................................................................................18
Biomimetic protocols ..................................................................................................................................19
- Stress-reducing protocols ....................................................................................................................19
1. Using indirect or semi-direct restoration ..........................................................................................19
2. Decouple with time.........................................................................................................................20
3. For large restorations, place fiber inserts on pulpal floor and/or axial walls to minimize stress on the
developing bond strength of the hybrid layer............................................................................................24
4. Use slow start and/or pulse activation polymerization techniques........................................................26
5. Use dentin replacing composites with shrinkage rates of less than 3% and with a modulus of elasticity
between 12 GPa and 20 GPa. .................................................................................................................26
6. When restoring pulp chambers in non-vital teeth, use dual cure composite with the chemical cure mode
active for the first five minutes................................................................................................................27
7. Remove dentin cracks completely within 2mm of the dentinoenamel junction......................................28
8. Limit onlay cusps to thinner than 2mm after removal of decay and cracked dentin. .............................29
9. Verticalize occlusal forces to reduce tensile stress to the restoration and the cervical region of the tooth.
29
Bond-maximizing protocols........................................................................................................................30
1. Establish a caries-free peripheral seal zone ......................................................................................30
2. Air abrade surfaces. .......................................................................................................................31
3. Bevel enamel..................................................................................................................................32
4. Deactivate matrix metalloproteinases (MMP). ..................................................................................35

3. 2 | P a g e
5. Employ gold standard bonding systems. ...........................................................................................35
6. Utilize immediate dentin sealing (IDS). ............................................................................................39
7. Resin coat the immediate dentin sealing...........................................................................................40
8. Achieve deep margin elevation ........................................................................................................40
What is C-Factor?.......................................................................................................................................40
How is C-Factor Reduced? .........................................................................................................................40
What is the role of fiber in controlling C-Factor?...........................................................................................42
The Biobase (BB) .......................................................................................................................................42
- Deep Margin Elevation (DME) ............................................................................................................42
- Immediate Dentin Sealing (IDS) ........................................................................................................42
- Resin Coating (RC)...........................................................................................................................44
- Thin layer of Fiber-Reinforced Composite.........................................................................................45
- DME ................................................................................................................................................46
Stress-Reduced Placement of DME Layers...................................................................................................47
No BioBase what happens ?......................................................................................................................47
Overlay or Onlay?.......................................................................................................................................48
- Preserving the BioRim and the Compression Dome Concept ...................................................................48
- Bonding Enamel Replacement to the Biobase ........................................................................................49
Example of Bonding Protocol......................................................................................................................50
Cementation Using Heated Restorative Composite ....................................................................................51

4. 3 | P a g e
Abbreviations
• AA – Air Abrasion
• AIL – Air Inhibition Layer
• APA – Air Particle Abrasion
• AP-X – Clearfil AP-X Kuraray
Composite
• BB – Biobase
• BD – BioDome
• Bis-GMA – Bisphenol A-glycidyl
Methacrylate
• BR – BioRim
• BRD – Biomimetic Restorative
Dentistry
• CDD – Caries Detector Dye
• C-Factor
• CHX – Chlorhexidine
• Clearfil SE Protect
• CRE – Caries Removal Endpoints
• CrRE – Crack Removal Endpoints
• CSZ – Central Stop Zone
• CQ – Camphorquinone
• DBS – Dentin Bonding System
• DDS – Delayed Dentin Sealing
• DEC – Dentino Enamel Complex
• DEJ – Dentino Enamel Junction
• Delibits
• DME – Deep Margin Elevation
• DWT – Decoupling With Time
• ETT – Endodontically Treated
Tooth
• EXF – Ever-X Flow FRC
• EXP – Ever-X Posterior
• FRC – Fiber-Reinforced Composite
• GS-DBS – Gold Standard Dentin
Bonding System
• HAp – Hydroxyapatite
• HL – Hybrid Layer
• HOB – Hierarchy of Bondability
• HSC – Horizontal Structural
Compromise
• HT – High Translucency
• ICD – Inner Carious Dentin
• IDS – Immediate Dentin Sealing
• IES – Immediate Endodontic
Sealing
• IPDS – Immediate Pre-Endodontic
Dentin Sealing
• Li2Si2 – Lithium Disilicate
• LT – Low Translucency
• MDP – 10-Methacryloyloxydecyl
dihydrogen phosphate
• MDPB – 12-
Methacryloyloxydodecyl pyridinium
bromide
• MID – Minimally Invasive Dentistry
• MMPs – Matrix Metalloproteinases
• MOE – Modulus of Elasticity

5. 4 | P a g e
• OCD – Outer Carious Dentin
• OCT – Optical Coherence
Tomography
• OEC – Occlusal Effect Caries
• OIL – Oxygen-Inhibited Layer
• Optibond FL
• PMMA – Polymethyl methacrylate
• PRF – Peripheral Rim Fracture
• PSZ – Peripheral Seal Zone
• RC – Resin Coating
• RD – Rubber Dam
• Ribbond
• SC – Structural Compromise
• SFRC – Short Fiber-Reinforced
Composite
• SLA – Six Lessons Approach
• SOOTR – Sub Occlusal Oblique
Transverse Ridge
• SRDC – Stress Reduced/Relieved
Direct Composite
• SRDR – Stress Reduced/Relieved
Direct Restoration
• SZ – Sub-transparent Zone
• TBS – Tensile Bond Strength
• TEGDMA – Triethylene Glycol
Dimethacrylate
• TL – Turbid Layer
• TZ – Transparent Zone
• UDMA – Urethane Dimethacrylate
• VSC – Vertical Structural
Compromise

6. 5 | P a g e
Introduction
In order to understand biomimetic restorative dentistry, first of all what does
biomimetic mean ?
The biophysicist/biomedical engineer Otto Schmitt in the 1950s, firstly used the
phrase “biomimetic” which is derived from Latin word “bio” meaning life, and
“mimetic” is related to imitating and copying something, so biomimetic restorative
dentistry is a branch of restorative dentistry that restore and maintain the tooth
structure using materials that mimic the natural tooth structures.
The aims of biomimetic dentistry are to restore the tooth to its function, strength, and
aesthetics. By conventional approaches, more tooth structures are removed, while the
destructed tooth structures are restored with rigid materials. The conventional
techniques and materials have weakened the tooth structures and shortened the life
span of restorations and Therefore, efforts to develop materials which mimic natural
tooth structures, regenerate and restore the lost tooth structures.
The main object of biomimetic restorative dentistry is to restore the hard tissues
(enamel and dentin) to gain full function by bonding to hard tissues. This allows
functional stresses to pass through the tooth making the entire crown into a unit that
provides near normal function, biologic and esthetic result. Unfortunately, there is no
such biomaterial that has the same mechanical, physical, and optical properties as that
of tooth structures (i.e., enamel, dentin, and cementum) but only closer to tooth
structure.

7. 6 | P a g e
Biomimetic Paradigms
Biomimetic restorative dentistry is founded on these four basic paradigms:
1. Maximum bond strength. Reducing polymerization stress to the developing hybrid
layer results in a 300% to 400% increase in bond strength.17-20 Dentin bond strengths
in the range of 30 MPa to 60 MPa are in the same range as the tensile strengths of
enamel, the dentinoenamel junction, and dentin.21 This strong bond allows the
biomimetically restored tooth to function and handle functional stresses like an intact
natural tooth.
2. Long-term marginal seal. A strong and secure bond allows for a long-term
marginal seal to be established and maintained during functional stresses.
3. Increased pulp vitality. By maintaining a highly bonded seal, the restoration will
provide long-term function without recurrent decay, dental fractures, or pulp deaths. A
vital tooth is also three times more resistant to fracture.
4. Decreased residual stress. Residual stress, while hard to visualize, leads to cuspal
deformation, debonding, gaps, cracks, pain and sensitivity, and recurrent decay.
Reducing residual stress while maintaining the maximum possible bond strength is the
ultimate goal of any biomimetic restorative technique.

8. 7 | P a g e
Caries Removal protocols
By histologic, microscopic, biochemical, biomechanics, and microbiologic techniques,
researchers have differentiated two layers of caries which were very different in
structure.
The outer layer is infected dentin. Which is very infected, acidic and demineralized.
This layer can be removed without anesthesia because it is not sensitive to contact. In
this layer collagen framework could not return to normal so it failed to get
remineralized.
The inner layer was affected dentin. It is slightly infected and partially demineralized.
It is sensitive to be removed without anesthesia, because the collagen fibrils remain
intact so it remains sensitive. The inner carious dentin has three zones: the turbid
layer, transparent zone, sub-transparent zone, and normal dentin.
.
Fig.1 The Deep Carious Lesion has two layers OCD and ICD
There are three zones of ICD: TL, TZ, SZ
OCD: Outer Carious Dentine, ICD; Inner Carious Dentine
TL; Turbid Layer, TZ; Transparent Zone, SZ Sub-Transparent Zone

9. 8 | P a g e
- Treatment goals
1. Create PSZ of enamel, DEJ and normal super facial dentin near DEJ
2. Leave inner carious dentin ICD inside peripheral seal zone (psz). It can bond at 30
Mpa. (Compare fig.4,5 and fig.2,3)
Fig.2
Ideal caries removal end points and
peripheral seal zone developed in an
intermediate-depth lesion
Fig.3
The peripheral seal zone is free of
outer and inner carious dentin.
Inside the peripheral seal zone, the
lightly stained inner carious dentin
is retained and will remineralize in
vital teeth.
Fig.4
The concept of a peripheral seal zone
is that the enamel, DEJ, and
superficial dentin constitute the
caries-free area of a highly bonded
adhesive restoration.
Fig.5
Caries removal end points for the peripheral
seal zone can be determined by caries-
detecting dyes.

10. 9 | P a g e
3. Remove highly infected outer carious dentin inside psz without exposing the pulp
and small area of outer carious dentin can be left to prevent pulp exposure.
4. Deactivate and seal any remaining bacteria left inside PSZ.
5. Use adhesive tech that will maximize bond strength of the PSZ and ICD inside
PSZ.
Fig.6
Deep caries lesion showing the outer
carious dentin staining red and
extending to the circum-pulpal dentin ( >
5 mm from the occlusal surface).
Fig.7
Caries removal end points for a deep
lesion. The peripheral seal zone has
been created without exposing the pulp.
A small amount of outer carious dentin is
left on top of the inner carious dentin
inside the peripheral seal zone.
Fig.8
Clinical case illustrating Fig 7. The
ideal caries removal end points for
highly bonded restorations without
pulpal exposure.

11. 10 | P a g e
- Step by step tech to achieve caries end point and peripheral seal zone.
1. Test for pulp vitality with ice if positive go for caries removal, if negative inform
patient for root canal treatment (RCT).
2. Anesthesia and isolate the tooth with rubber dam.
3. Access the lesion after removal of any failed restoration.
4. Stain the caries with red CDD wait 10 seconds and rinse.
5. Starting near the DEJ, use 1mm round diamond bur to create peripheral seal zone
(plz) area of red stained outer caries and pink stained inner caries. (see fig.2&3)
6. Staining and removing outer and inner caries is repeated until the caries removal
end point in PSZ is stain free. (see fig.5)
7. Remove the red-stained outer carious dentin from the area inside the peripheral seal
zone (being careful to avoid the pulp horn areas). Measure from the occlusal surface to
determine if the excavation is in superficial (outer third), intermediate (middle third),
or deep (pulpal third) dentin dentin ( > 5 mm from the occlusal surface). (see Fig 1).
8. After removing the red area and leaving the pink between pulp horns, to be sure
bacteria free area in our peripheral seal zone. (see fig.2&3)
Fig.9
Application of caries-detecting dyes guides
the creation of the peripheral seal zone
using to make end point decisions in the
intermediate and deep dentin areas.

12. 11 | P a g e
9. Move to deep pulp horns if tissues continue to give red stain and the periodontal
probe indicate that you aren’t deeper than 5mm from occlusal surface and 3mm
from DEJ. If so, stop excavation to prevent pulp exposure. (fig. 6-8)
10. Optional step: treat PSZ, ICD and OCD with CHX 0.2 to 2.0% to
inhibit MMPs and residual bacteria to prevent deterioration of hybrid layer, if using
total etch bonding system this step should be performed after etch & rinsing. If using a
self-etch bonding system, apply CHX for 10 seconds then dry before self-etch primer
application.
11. Finally if using two step self-etch bonding system, it's preferred to use air
abrasion before to maximize the micro tensile bond strength.
At the end we should have:
1-PSZ (peripheral seal zone )2 mm from the DEJ it should be no longer stains Red or
Pink then move to central grooves and fossae.
2-No (white spot lesions) after dehydration of the peripheral enamel.

13. 12 | P a g e
Structural analysis
- How is Structural Compromise Assessed?
Structural compromise is assessed by checking the tooth for 4 red flags, and also by
taking a detailed history from the patient.
- What are the 4 Red Flags?
1) Cracks into dentin
2) Isthmus width > 2 mm
3) Cusp thickness < 3 mm
4) Box depth > 4 mm
1) Cracks into dentin
Cracks into dentin can sometimes be visualised as Peripheral Rim Fractures
(PRF). In order to determine if a PRF extends into dentin, the patient’s history
(e.g. sensitivity to cold/sweet or pain on biting) and overall assessment of
structural compromise must be taken into account.
2) Isthmus width > 2 mm
In 1981, Larson, Douglas, and Geistfeld analysed the effect of cavity
preparation on the strength of teeth. They found that creating an isthmus width
of 1.5 mm resulted in a 40% reduction in fracture resistance. By creating an
isthmus width of 2 mm, the fracture resistance was reduced by 60%.
Fig. 10
Peripheral Rim Fracture (PRF).

14. 13 | P a g e
Similarly, Magne and Oganesyan carried out a finite element analysis study of
cuspal deflection following operative procedures in 2009. Their study compared
the micromovement of unbonded restorations and bonded restorations. The
following results were obtained in terms of the micromovement of cusps:
• No cavity prepared – 2.7 microns
• MOD cavity unbonded – Up to 180 microns
• MOD cavity restored using composite – 6.9 microns
An amalgam restoration or unbonded composite restoration can cause the tooth
to be flexing in a non-biomimetic way, leading to further caries and fracture.
3) Cusp thickness < 3 mm
A cusp which measures less than 3 mm in thickness is considered a “dry” cusp.
The cusp is no longer hydrated as the connection between the pulp and DEJ via
the dentinal fluid is lost. A “dry” cusp measuring less than 3 mm in thickness
can flex 3x as much as a hydrated cusp.
Fig.11
Isthmus width of > 2 mm.
Fig.12
Cusp thickness < 3 mm when
measured from the base

15. 14 | P a g e
4) Box depth > 4 mm
A box depth of 4 mm (measured vertically from the marginal ridge of the
adjacent tooth) extends into the BioRim of the tooth. Beyond 4 mm, enamel in
the BioRim region is decussated, meaning that the prisms are irregularly
arranged and are not in a normal configuration. Enamel in this region should not
be beveled as a uniform bevel cannot be achieved – a butt margin should be
used.
If the BioRim has been lost, it can be restored using Deep Margin Elevation
(DME). Optimal stress-reducing protocols are required in these areas.
- The Rainey Ridge & Peripheral Rim Fractures (PRF)
The sub-occlusal oblique transverse ridge (also known as Rainey Ridge) is a structure
which runs underneath the pits and fissures of the tooth, helping to connect the tooth
together side to side; front to back; and top to bottom.
If a traditional cavity preparation is carried out and these ridges are cut, the tooth is no
longer connected in a biomimetic way. The tooth is now able to open and close and can
flex in a range of around 200 microns. This can result in stress concentration. Fracture
resistance decreases and the marginal ridges are more likely to crack, leading
to Peripheral Rim Fractures (PRF).
Fig.13
Box depth > 4 mm.

16. 15 | P a g e
- Crack Propagation
Cracks can propagate when under occlusal loading. As discussed previously, teeth will
generally bend and flex, and will fatigue over time before eventually fracturing. A small
crack requires more force to be applied in order to propagate. Longer cracks require less
force to be applied before propagation occurs.
After carrying out structural analysis using the 4 red flags method, take a thorough history
to determine if the patient has had any sensitivity to cold, sweet, or when biting. Also
check if the patient has had any symptoms in the past. As written by Brannstrom in 1986,
remineralization of the cracks can result in temporary relief of symptoms due to tertiary
dentin formation and reduction in hydrodynamic movement. This can make diagnosis of
cracked tooth syndrome very difficult.
- Managing Cracks
Cracks into enamel may be considered biomimetic, as by restoring the tooth back
together adhesively, the resulting flexure of the tooth is unlikely to cause catastrophic
fracture or secondary caries. Cracks into dentin, however, cannot be considered
biomimetic and should be dissected where possible.
Techniques such as providing full coverage crowns, partial onlays, carrying out occlusal
adjustment or simply bonding over cracks using composite or fiber such as Ribbond, are
unlikely to be successful in these situations. This is because the crack is still present, and
the crack can therefore still continue to propagate. Providing partial coverage onlays or
attempting to bond over horizontal or oblique cracks may provide some initial benefit, but
this method is unlikely to be successful for vertical cracks.
Oblique/horizontal cracks are less likely to lead to pulpal death. If these are not identified
then the most common sequelae would be cuspal fracture. Vertical cracks are more likely
to lead to pulpal death or catastrophic fracture.
Crack dissection should be considered as the technique of choice.

17. 16 | P a g e
- Crack Visualization
As with all techniques, high magnification is strongly recommended.
Old cracks are likely to stain darker and can therefore be identified more easily. Newly
formed cracks are usually lighter in appearance, and can therefore be more difficult to
visualize. If onlaying a thin cusp is appropriate then this may help with crack
visualization.
I) Visualization by Crack Dehydration
When assessing an oblique or horizontal crack, it can be difficult to distinguish any
notable difference in opacity without drying the tooth. After air drying the tooth for 10
seconds, the dentin above the crack will appear more opaque as it receives less
hydration from the pulp. In relation to vertical cracks, each side of the crack receives
similar levels of hydration from the pulp, and therefore alternative techniques should
be considered.
II) Visualization by use of Primer
Applying a layer of primer can alter the light refraction of the crack. This can allow
better visualization.
- Dissection of Cracks and Crack Removal Endpoints (CrRE)
If it is necessary to remove a restoration in order to assess for cracks, or if cracks are
encountered during an operative procedure, crack dissection should be carried out
and Crack Removal Endpoints (CrRE) should be followed. The aim is to remove cracks
without exposing the pulp. Measurements of 3 mm horizontally from the adjacent tooth’s
marginal ridge and 5 mm vertically from the cavity margin are used. Crack removal is
halted at this point, in a similar way to the Caries Removal Endpoints (CRE) in order to
achieve a Peripheral Seal Zone (PSZ) free from cracks. The area over the pulp, encircled
by the PSZ, is commonly referred to as the Central Stop Zone (CSZ).

18. 17 | P a g e
The aim of crack dissection is to remove the crack in order to prevent future crack
propagation. The technique is based on engineering principles. Complete crack removal in
the PSZ is aimed for. If partial crack removal is achieved then there is a chance that the
crack will continue to propagate, however as the lever arm of the crack has been
shortened, greater force is required to cause crack propagation. Perforation or pulpal
exposure should be avoided.
If partial crack removal is carried out in the Central Stop Zone (CSZ), placement of
Ribbond (leno woven ultra high modulus polyethylene fibre) is recommended within the
Biobase. This can help to reduce stress concentration at the crack interface by redirecting
forces.
Restoration of the dissected crack should involves applying layers of Immediate Dentin
Sealing (IDS) and Resin Coating (RC) as normal, followed by restoration with thin
horizontal layers of composite resin. AP-X (dentin-replacing composite) or EverX
Posterior (Short Fiber-Reinforced Composite) are commonly used in small 1 mm
increments. Restoring crack dissections is very challenging due to the high C-Factor
environments encountered.
Fig.14
Crack Removal Endpoints (CrRE) can be
measured using periodontal probes, in a
similar way to Caries Removal Endpoints
(CRE).
Fig.15
Clinical example of crack dissection. Top-left: structurally
compromised pre-molar and molar with visible cracks.
Top-right: after amalgam removal from the pre-molar,
several vertical cracks are visible. Bottom-left: Crack
Removal Endpoints (CrRE) achieved. Bottom-right:
Biobases formed, ready for impression/scan for indirect
restorations.

19. 18 | P a g e
- Occlusal Effect Caries (OEC)
Occlusal Effect Caries (OEC) is caries that forms as a result of biofilm formation inside
cracks. These cracks are commonly a result of Peripheral Rim Fractures (PRF). Bacteria
enters through the PRF which is located on the occlusal aspect of the tooth. This type of
caries can be more difficult to detect on radiographs, as the typical interproximal
radiographic appearance will likely not be present. The following clinical example of
OEC has been kindly provided by Dr Ashley Chung.
Fig.16
Structurally compromised tooth with an occlusal
amalgam restoration and mesial PRF noted.
Fig.17
Clinical example of OEC.
Fig.18
Note the OEC starting at the DEJ, with a relatively
intact enamel surface.

20. 19 | P a g e
Biomimetic protocols
- Stress-reducing protocols
1. Using indirect or semi-direct restoration for the occlusal and interproximal enamel
replacements. Indirect technique is the most stress-reduced technique. It reduces the
volume of shrinking restorative material. This also reduces residual stress
Fennis et al. in 2004, functional cusps (palatal cusps of the upper teeth and buccal
cusps of lowers) that measure <2 mm in thickness, and non-functional cusps <3 mm
should be reduced and covered. The cusp thickness should be measured from the base
of the cusp.
Fig.19
Old
restoration
was removed
, cusps
reduced
,biobase
created and
indirect
overlay
cemented
Fig.20
Cusps thickness measured using caliber

21. 20 | P a g e
2. Decouple with time. This protocol states that polymerization shrinkage stress to the
developing dentin bond of the hybrid layer should be minimized for a certain period of
time (ie 5 to 30 minutes) by keeping initial increments to a minimum thickness (ie less
than 2mm). This minimal thickness prevents the connection, or “coupling,” of deep
dentin to enamel or superficial dentin before the hybrid layer is matured and close to
full strength. This procedure neutralizes the “Hierarchy of Bondability,” which states
that the shrinkage of composite moves toward (or “flows” toward) the walls of the
preparation that are the most mineralized and dry and flows away from the walls of the
preparation that are the most moist and organic.
What is Decoupling With Time (DWT)?
From the moment that IDS is carried out, the bond to dentin begins to develop and the
hybrid layer starts to mature. The bond strength does not reach its maximum potential
immediately – it takes time to develop.
The 2004 study by Lu et al. shows that the dentin bond reaches 90% of its potential
strength after 5 minutes.
After the IDS is placed, the Resin Coating can be placed. This is commonly applied
using a periodontal probe, being careful to spread evenly in 0.5 mm thickness over the
dentin and DEJ. The layer of Resin Coating is moving towards the developing hybrid
layer during polymerization. By allowing the dentin bond to Decouple With Time
(DWT), the bond is allowed to reach its full potential without being pulled towards the
faster-forming enamel bond. DWT also helps to overcome potential issues relating to
the Hierarchy of Bondability, by allowing each dental substrate to form its maximum
potential bond strength in a stress-free environment.

22. 21 | P a g e
If a direct restoration is being carried out, the dentin bond should be allowed to
develop in a stress-free environment for at least 5 minutes to allow the hybrid layer
sufficient time to mature. During this 5 minutes, further tasks can be completed such
as management of C-Factor stresses using fiber inserts, or carrying out Deep Margin
Elevation (DME).
Restore the dentin with thin horizontal layers of composite that are 1mm or less. This
ensures that decoupling with time is properly achieved and that the flow of the
composite is not moving away from the deep dentin during the early stage of
horizontal layer development. This is the solution to the problem of a preparation’s
complex geometry and the resulting configuration stresses, which are known as “C-
Factor” stresses. Small volume increments are always associated with small ratios of
bonded to unbonded surface areas; thus, high C-Factor stresses can be reduced to
“micro C-Factor” stresses. This is the basic protocol of the stress-reduced direct
composite technique.
Fig.21
Biomimetic layering technique vs traditional technique vs bulk fill
Biomimetic technique shows minimal shrinkage stress while bulk-fil shows the highest
shrinkage stress and traditional shows moderate shrinkage stress

23. 22 | P a g e
What's Hierarchy of Bondability ?
Hierarchy of Bondability (HoB) explains the ability of bond formation between resins
undergoing polymerization reaction and certain tooth structures Therefore if we connect
dentin and enamel surfaces together with composite at the same time, we will stress the
hybrid layer due to being pulled towards the enamel
Fig.22
Fig.23

24. 23 | P a g e
The maximum bond strength of enamel happens
after 5 minutes
The maximum bond strength to dentin happens
after 30 minutes
Bond formation to enamel happens at a
greater rate, with an increases %
polymerisation and complete bond formation in the
first 5 minutes.
There is a slower formation of bonds to dentin, as
the maturation of bonding takes longer.
Fig. 24
Fig. 25
Fig. 26

25. 24 | P a g e
3. For large restorations, place fiber inserts on pulpal floor and/or axial walls to
minimize stress on the developing bond strength of the hybrid layer. The fiber nets
allow the composite on either side of the net to move in different directions via micro
shifting of the woven fibers. The polymer network is still highly connected, but the
polymerization shrinkage does not stress the hybrid layer
Dentine replacements
• Clearfil.AP-X/Ever-X and Ribbond
o Fibre reinforced composite.
o Mimics modulus of elasticity of dentin.
o Has a low shrinkage during polymerisation
Therefore doesn't stress the bio-base or hybrid layer.
- Ribbond
Fig.27 Ribbond
1. ribbond fibers, 2. the fibers need to be thoroughly wetted with an unfilled enamel bonding resin
3. applying bonding agent 4. Applying the ribbond fibers 5. Light curing
1
2
3
4 5

26. 25 | P a g e
- Ever X Composite
The short fibres of everX Posterior will make it a perfect sub-structure to reinforce
any composite restoration in large size cavities.
Fibres will also prevent and stop crack propagation through the filling, which is
considered to be the main cause of composite failures.
- AP-X composite
Fig.30
Fiber-reinforced
composite prevent crack
propagation in large
restorations
Fig.28
everX Posterior, fiber reinforced
composite from GC
Fig.29
AP-X, fiber reinforced
composite from Kuraray

27. 26 | P a g e
4. Use slow start and/or pulse activation polymerization techniques
5. Use dentin replacing composites with shrinkage rates of less than 3% and with a
modulus of elasticity between 12 GPa and 20 GPa.
Fig.31
Light curing cycles, slow start (B) and Pulsating waves (C) are better
Fig.32
Volumetric shrinkage of different composite restoration materials
The less shrinkage rate the better the material, note everX
posterior has 3% shrinkage rate which is optimum, GCC R&D,
2018. Test method: as per ISO17304(2013)

28. 27 | P a g e
6. When restoring pulp chambers in non-vital teeth, use dual cure composite with the
chemical cure mode active for the first five minutes. The volume of composite is not
as critical for chemically cured composites because the chemical initiation of the
polymerization is very slow (4 minutes to 5 minutes). This slow polymerization allows
sufficient time for the dentin bonding system to mature into a strong hybrid layer.
Fig.33
Modulus of elasticity of different composite restoration materials,
between 12-20 GPa is optimum, Notice everX posterior has 12.3 GPa,
GCC R&D, 2018. Test method: as per ISO4049(2009)
Fig.34
Zircore NANO from Oxford, is a dual cure composite so its useful when
restoring pulp champers

29. 28 | P a g e
7. Remove dentin cracks completely within 2mm of the dentinoenamel junction. This
area is referred to as the “peripheral seal zone.” Remove all dentin cracks inside of the
peripheral seal zone to a depth of 5mm from the occlusal surface and to a depth of
3mm interproximally from the axial wall. If cracks into dentin are left under the
restoration, micro-movements under function will allow the cracks to get longer (ie
crack propagation). Larger cracks propagate with smaller forces than shorter cracks;
therefore, it is recommended to remove as much of the cracked dentin as possible
without exposing the pulp.
Fig.35
a. Initial situation. Old, large, unacceptable class-I
composite restoration. Cracks are present at the
mesial, distal and palatal side.
b. Residual dental structure after removal of the
existing restoration and infected dentin. Crack lines
are running from the mesial and palatal side towards
the center of the cavity. In this deep, wide cavity with
completely undermined cusps, total cusp reduction is
needed.
c. Detailed analysis of the cracks in the tooth (blue
arrows).
d. The cusps were circumferentially reduced until a
level that enamel was completely supported by
dentin.
e. The crack was sandblasted with Al2O3 powder (30
μm).
f. After sandblasting, the crack line is contaminated
with the non-hydrosoluble Al2O3 powder particles.
g. Cleaning of the crack line with sodium bicarbonate
(40 μm) air polishing, followed by generously rinsing
with an air-water spray.
The prepared tooth was ready for immediate dentin
sealing.

30. 29 | P a g e
8. Limit onlay cusps to thinner than 2mm after removal of decay and cracked dentin.
This will change the forces on the hybrid layer from predominantly tensile to
predominantly compressive, which helps reduce bond fatigue.
9. Verticalize occlusal forces to reduce tensile stress to the restoration and the cervical
region of the tooth. This can be done by restoring anterior guidance with bonded
composite to the lingual surface of maxillary cuspids and/or the facial surfaces of
mandibular cuspids.
Fig.36
Onlay cusp thickness should be thinner than
2mm to reduce bond fatigue
Fig.37
Occlusal forces
Fig.38
Canine guidance

31. 30 | P a g e
Bond-maximizing protocols
1. Establish a caries-free peripheral seal zone. Achieve a caries-free zone 2mm to 3mm
circumferentially around the cavity without exposing the pulp. Inside of the peripheral
seal zone, caries excavation should be limited to a depth of 5mm, measured on the
long axis from the cavo-occlusal surface. Measuring from the proximal tooth, the
depth of excavation should be limited to 3mm from the cavo-proximal surface
Fig.39
PSZ, OCD, ICD
The excavation should stop when
- measuring 5mm form cavo-occlusal surface using
preio probes (to prevent exposure)
- measuring 3mm from cavo-proximal surface
Fig.40
Caries Removal End-Points
And PSZ (2-3mm) completely free of
any caries or cracks

32. 31 | P a g e
2. Air abrade surfaces. Air abrade composite surfaces for bonding/cementation. This
will increase bond strength to both normal and carious dentin. It will also change the
failure mode to eliminate failures in the hybrid layer. When bonding to the composite
base of a biomimetic restoration, air abrasion will maximize the composite-to-
composite bond.
Fig.41
Air abrasion device using aluminum
oxide particles
Fig.42
Case presentation using biomimetic protocols

33. 32 | P a g e
3. Bevel enamel. Bevel enamel across enamel rods to increase bond strength
Fig.43
Different types of enamel beveling
Fig.44
Effect of enamel beveling on stress concentration, the more the bevel the less the
stress concentration

34. 33 | P a g e
Enamel Replacement (Enamel Preparation And Adhesive Preparation Design &
Cementation)
o Enamel Rod/Prism Orientation
The tensile strength of enamel is dependant on the orientation of the enamel rods or
prisms. The study by Carvalho et al. in 2000 found that the tensile strength of
enamel with prisms positioned parallel to an applied load was 24.7 MPa. With a
perpendicular load applied to the enamel prisms, the tensile strength was found to
be 11.4 MPa.
o Beveling Enamel
Appropriate beveling can help to prevent separation of the enamel at the orientation
lines of the rods/prisms.
There are several methods of beveling enamel e.g. by using finishing burs. Another
system available is the Sonicsys by Kavo which contains a smooth side and a diamond
side, with a vibrating tip.
o Bevel or Butt Joint?
Gingival enamel should only be beveled if:
• It is thicker than 1.5 mm
• Box depth is less than 4 mm.
If the enamel is thinner than 1.5 mm or the box depth is >4 mm, then a butt joint
should be opted for. This is because the enamel in this region is decussated, meaning it
has an irregular orientation and a uniform bevel cannot be achieved.
o Cusp Thickness and Occlusal Reduction
The cusp thickness should be measured from the base of the cusp using callipers. It is
commonly recommended that holding (functional) cusps <2 mm and tension (non-
functional) cusps <3 mm should be onlayed. Depth grooves should be created of
known depth (2-3 mm), and these grooves should then be connected using a straight
diamond bur.

35. 34 | P a g e
The holding/functional cusps (palatal cusps of the upper teeth and buccal cusps of
lowers) should be preserved where possible, as long as the thickness at the base of the
cusp is at least 2 mm.
Optimum stress-reduced techniques (e.g. the “wallpapering” technique if the final
restoration is a Stress Reduced Direct Composite) can be used in some cases to reduce
the cusp thickness below even 2 mm.
A hollow chamfer can be beneficial in aesthetic areas in order to improve the blend
between tooth and restorative material at the margin. This is created using a modified
bevel with a large round diamond bur. Illustration to follow.
o Rule of BULL
Buccal cusps of Uppers and Lingual cusps of Lowers are more likely to crack. There
is no cusp-fossa relationship in their envelope of function and therefore they are under
tension rather than compression. For this reason, tension cusps should be onlayed if
thickness <3 mm.
Fig.45
Clinical photographs showing the use of
callipers to measure cusp thickness from the
base of the cusps. The mesiobuccal cusp (left) is
<3 mm and is therefore reduced in height by 2
mm and onlayed. The distobuccal cusp (right)
has appropriate thickness to be retained.
Fig.46
Note the mix of direct and indirect approaches in this
case by Dr Davey Alleman. A direct approach is used
in order to preserve the mesiopalatal holding cusp,
followed by fabrication of an indirect restoration.
From left to right: (1) CRE and PSZ established.
(2) Biobase created. (3) Final restoration.

36. 35 | P a g e
4. Deactivate matrix metalloproteinases (MMP). This prevents 25% to 30% of bond
strength from being degraded. Deactivation can be achieved by using a 30 second
treatment with 2% chlorhexidine (eg Consepsis, Ultradent), benzalkonium chloride (eg
Micro-Prime B, Danville or Etch 37, Bisco), or a dentin bonding system with the
MDPB monomer (eg SE Protect, Kuraray).
5. Employ gold standard bonding systems. Use a gold standard dentin bonding system
that can achieve a microtensile bond strength of 25 MPa to 35 MPa on enamel and 40
MPa to 60 MPa on flat dentin surfaces. The available data indicates that three-step
total etch dentin bonding systems and two-step self-etch dentin bonding systems offer
the best clinical performance.
Fig.47
Consepsis from Ultradent
Fig.48
Etch 37 from Bisco
Fig.49
Micro Prime B from Bisco
Fig.50
SE protect, from Kuraray

37. 36 | P a g e
o Three-step total etch
OPTI-BOND FL
▪ Three stage, Total Etch bonding system
▪ Etch 37% Phosphoric acid
▪ Prime (Re inflates collagen in HL)
▪ Bond (Resin filled, produces resin tags into hybrid layer)
▪ Solvent Ethanol
▪ Dentin 31.4 Mpa
▪ Enamel 32.5Mpa
Fig.51
Three-step bonding
system of OptiBond FL
from Kerr
- Total etch then
1)prime 2)bond
Fig.52
Three-Steps Bonding system
Procedure
A) Etch Enamel 20-30 seconds
B) Etch Dentin 5-10 seconds
C) Prime Dentin and Enamel 20
seconds then air dry for 10 seconds
D) Apply adhesive in uniform layer
and Light Cure 20 seconds

38. 37 | P a g e
o Two-step self-etch
CLEARFIL SE BOND & SE PROTECT
Two stage Self Etch bonding system
▪ Self-etch primer- primer is acidic and etches whilst primer re-inflates
collagen.
▪ Bond (Resin filled, produces resin tags into hybrid layer)
▪ Solvent Water
▪ Dentin 31.8 Mpa
▪ Enamel 32.5Mpa
Fig.53
Two-Step Bonding system,
- CLEARFIL SE Protect Primer &
BOND from KURARAY
- CLEARFIL SE Primer & BOND from
KURARAY
The difference between them
Clearfil SE Protect has fluoride-releasing
properties and a new functional monomer
“MDPB,” which exhibits an “Antibacterial
Cavity Cleansing Effect.” Clearfil SE Bond
does not have these properties.
Fig.54
Two-Step Bonding procedure
A) Prime Dentin and Enamel
20 seconds, Air Dry 10
seconds
B) Apply Adhesive in uniform
layer wick away excess
bond with fresh dry micro-
brush, light cure 20
seconds

39. 38 | P a g e
During light curing of bonding agents interfacial gaps between dentin and bonding agent can
occur.
This reduces micro tensile bond strength both within dentin and enamel bonding.
This gap formation can also cause post-op sensitivity, marginal leakage and secondary caries
EVEDANCE SHOWS THAT GOLD-STANDARD BONDING SYSTEMS
- OptiBond FL
- ClearFil SE
- ClearFil SE Protect
Have NO to the least amount of interface
gap formation, incomparison to other
bonding agents.
Hayashi et al 2017
Fig.55
Fig.56
Interface gab
formation

40. 39 | P a g e
Is air thinning of bonding agent is better?
Air thinning bond can increase the thickness of oxygen inhibition layer in you resin bonding
agent.
- Camphor quinone molecules are turned into impotent peroxides that cannot produce free
radicals.
- This meaning free radical polymerisation is limited and reduces bond strength.
-Instead Wick away excess bond with a fresh micro brush!
o What is the Oxygen-Inhibited Layer?
The Oxygen-Inhibited Layer (OIL/Air Inhibition Layer/Oxygen Inhibition Layer) is
the layer in which full polymerization of the resin has not occurred due to the presence
of oxygen. The oxygen can react with free radicals, rendering these unable to induce
polymerization of the monomers to oligomers and polymers. This layer can commonly
be between 10 and 40 microns in thickness.
This can be resolved by:
- Providing more free radicals by addition of a layer of Resin Coating.
- By applying a layer of glycerine in order to block oxygen, and curing through this
layer of glycerine. Note: this should only be carried out if curing the final layer of
resin e.g. the final layer of the Biobase for an indirect or semi-(in)direct restoration,
or the final, outermost layer of composite resin if carrying out a direct restoration.
It is not necessary to cure the IDS/RC through a layer of glycerine if carrying out a
direct restoration at the same appointment, as the subsequent layers of resin will
provide the free radicals necessary at this stage.
The Oxygen-Inhibited Layer is important to consider when creating a Biobase using a
bonding system with a thinner adhesive layer. For example, the adhesive layer of
Clearfil SE Protect is much thinner than the adhesive layer of Optibond FL. If no RC
is placed then this layer may be left vastly unpolymerized. By placing a layer of RC,
the thickness is increased in order to combat the effects of the Oxygen-Inhibited Layer
in this vital area. Due to the increased thickness of the Optibond FL adhesive layer, it
may be appropriate to use an additional layer of Optibond FL adhesive as an RC layer.
6. Utilize immediate dentin sealing (IDS). The application and polymerization of dentin
bonding agents at the time of preparation (and before an impression is taken) has
numerous advantages and will ultimately increase the microtensile bond strength by
400% when compared to the traditional approach of bonding the dentin at the
cementation appointment. This is fundamental to achieving maximum bond strength.

41. 40 | P a g e
7. Resin coat the immediate dentin sealing. This can be done with a flowable resin or a
lower viscosity restorative composite with a modulus of elasticity of around 12 GPa
(ie the same as deep dentin). This ensures that the dentin bonding system is fully
polymerized even if the pressure of pulpal fluid transudation (in conjunction with the
air-inhibited layer) has made the adhesive too thin to be polymerized due to air-
inhibition. Once the dentin bonding system is resin coated and the resin coating is light
polymerized, the air inhibition and transudation stop. This step also creates a “secure
bond,” which means that if the onlay was ever dislodged from the resin coating, the
resin coating would stay bonded to the sealed dentin. A few dentin bonding systems
have thicker and highly filled adhesives (ie around 80 microns). These dentin bonding
systems can act like a resin coating. Examples include OptiBond FL (Kerr), All Bond
3 (Bisco), and PQ1 (Ultradent).
8. Achieve deep margin elevation. A sub-gingival box margin needs to be bonded and
raised to a supra-gingival position to obtain a biomimetic microtensile bond strength
greater than 30 MPa. This deep margin elevation, in conjunction with immediate
dentin sealing, resin coating, and the composite “dentin replacement,” is referred to as
the “bio-base”—a term used by the Academy of Biomimetic Dentistry for the stress-
reduced, highly bonded foundation that the indirect or semi-direct inlay or onlay will
be bonded to.
What is C-Factor?
C-Factor, or Configuration Factor, is defined as the ratio of bonded to unbonded
surfaces. Higher C-Factors lead to higher stresses.
How is C-Factor Reduced?
o Make use of thin layers of composite
A thin layer of composite (e.g. a layer of composite <1 mm in depth) should
be placed over the Immediate Dentin Sealing (IDS) and Resin Coating (RC)
layers. This thin layer of composite has a lower C-Factor as the ratio of
bonded to unbonded surfaces is reduced.
o Reduce structurally compromised cusps and include these in the onlay
design
By including structurally compromised cusps in the onlay design, this can
also help to reduce C-Factor forces as the shape of the preparation is
changed.

42. 41 | P a g e
As per the paper by Fennis et al. in 2004, holding (functional) cusps that
measure <2 mm in thickness, and tension (non-functional) cusps <3 mm
should be onlayed. The cusp thickness should be measured from the base of
the cusp.
o Consider the resulting shape of the preparation
A “plate” preparation with 1 side will have a low C-Factor. A “bowl”-shaped
preparation with 2-3 sides will have a medium C-Factor. Finally, a “cup”
preparation with up to 5 sides will have a high C-Factor. There are many
variations within these shapes.
o The type of layering technique used
The 2004 paper by Nikolaenko et al. shows that the placement of composite
in thin horizontal increments results in greater bond strengths than vertical or
oblique increments.
By ensuring that different substrates are not connected too early while the
dentin bond is maturing, the hybrid layer is able to form in a stress-free
environment. This relates to the concepts of Hierarchy of Bondability (HOB)
and Decoupling With Time (DWT).
Research by Bicalho et al. in 2014 confirmed that placing composite in
increments, compared to bulk-filling, increases bond strengths between 100-
300% depending on the thickness of the increments. The resulting residual
stress produced during polymerization is transferred to the residual tooth
structure and results in less stress being placed on the maturing dentin bond.

43. 42 | P a g e
What is the role of fiber in controlling C-Factor?
By placing a fiber insert, such as Ribbond, on the pulpal and/or axial walls,
stress on the developing dentin bond and the maturing hybrid layer is reduced,
as the Ribbond fibers have been shown to deform under polymerization stress.
A 2 mm ball of composite (or a “Delibit” as per the “Wallpapering Technique”)
is compressed onto the floor of the cavity, resulting in a layer of 1 mm. The
fiber e.g. Ribbond is wetted appropriately and inserted in the 1 mm layer then
cured.
EverX, which is a Short Fiber-Reinforced Composite (SFRC), can also be used
to direct the flow of composite towards the developing hybrid layer.
The Biobase (BB)
The Biobase is made up of the following layers:
- Immediate Dentin Sealing (IDS)
- Resin Coating (RC)
- Thin layer of Fiber-Reinforced Composite
- Deep Margin Elevation (DME)
- Immediate Dentin Sealing (IDS)
o First theorised in 1992 in Japan.
o Landmark paper by Pascal Magne in 2005 proving that IDS quadruples bond
strength in indirect restorations.
o First layer of biobased
o First layer for all direct and indirect (where dentin is being bonded too)
As soon as the dentine is cut during cavity preparation or indirect preparation, the
cavity enamel and dentine "Immediately Sealed"

44. 43 | P a g e
Advantages of IDS
I. Improves bond strength 4x in indirect restorations.
2.Allows you to have a cohesive strength in 50-60 Mpa, thus the same strength as the
DEJ, therefore biomimetic.
3.Reduction in bacterial ingress - sealed dentine tubules.
4.Reduction in dentine sensitivity (c-factor/hierarchy of bondability).
5.IDS heals pulp (Due to Gold standard dentine bonding agent).
Why IDS increase bond strength so much?
The reaction of the bonding system to the dentine is via free radical polymerisation
takes 5 minutes to produce 80% of polymerisation and 30 mins to get to 90%.
If you allow the bond to mature the shrinkage of the bond is towards the tooth (the
centre of mass) this producing a void free, high strength micro tensile bond.
If you try to restore the cavity immediately after the IDS (bonding) or if you try to
cement an indirect restoration immediately after bonding the polymerisation flow is
now in the direction of the restoration the 'new center of mass.
The hybrid layer in the dentine bond can not mature and pulls towards the restoration.
This causing failing bonds, reduction in bond strength, and voids under your dentin
bond

45. 44 | P a g e
- Resin Coating (RC)
On top of the IDS you do a resin coat layer, this is the 2nd layer of the "biobase"
Resin coat is only over dentin
The resin coat layer is produced by using a low-shrinkage flowable composite e.g
Magesty Flow.
Using a BPE probe spread the composite onto the IDS layer, to a thickness of
0.5mm (500 microns
Fig.57
BioBase , IDS + RC
Fig.58

46. 45 | P a g e
- Thin layer of Fiber-Reinforced Composite
For e.g. everX, AP-X
IDS + RC + Dentin Replacement (Fiber reinforced composite) = BioBase
- Bio-base is designed in such a way to maximize bonding to dentin.
- After IDS (dentin bonding) and RC, the amount of composite above this should not
exceed 1.5mm
- This minimizes the stress on the hybrid layer.
- This helps reach bond strengths of 40-60 MPa (Similar to that of dentin)
- As the bond polymerizes the monomers in bond and composite 'flow' towards the
Hybrid Layer This is called: POLYMERIZATION FLOW
- This only happens if within the first 5 minutes of bonding, composite does not
exceed 1.5mm
- The shrinkage is towards the center of mass (the tooth), therefore the hybrid layer
isn't stressed and is allowed to mature.
Fig.59
BioBase = IDS +
RC + dentin
replacing composite

47. 46 | P a g e
- DME
What is Deep Margin Elevation (DME)?
Deep Margin Elevation (DME) refers to the technique by which the restorative margin
in a deep box preparation is raised to the level, or above the level, of the gingival
margin. Gold standard isolation is necessary and complex matricing techniques are
often required. DME allows isolation to be more easily achieved for indirect
restoration cementation, among many other benefits. DME can be used as an
alternative to crown lengthening surgery.
Bressner et al. showed in the 2019 paper that the survival rate of DME over 12 years
was 95.9%.
Fig.60
Polymerization flow towards the center of the tooth

48. 47 | P a g e
Stress-Reduced Placement of DME Layers
A Resin Coating (RC) layer should be placed over the Immediate Dentin
Sealing (IDS) layer.
The second thin layer of composite is commonly placed using AP-X composite.
A layering technique is used, with either thin horizontal increments or a
peripheral layer which is deliberately not connected to the axial wall over the
pulp, in order to allow time for the dentin bond over the pulp to mature.
After allowing time for the hybrid layer to mature, the peripheral wall is then
connected to the axial wall.
No BioBase what happens ?
If there is no 'Bio-base' and we just use bulk fill or just slap in composite
what happens?
- The center of mass becomes the restoration.
- The 'polymerisation flow' is towards the restoration.
- The hybrid layer cannot mature and there is a reduction in % polymerisation
- Reduction in bond strength
Fig.61
Polymerization flow towards the
restoration

49. 48 | P a g e
Overlay or Onlay?
There are many different approaches to non-retentive, adhesive preparation designs.
The 2018 paper by Politano et al. referenced below shows several examples, as well as
the 2017 paper by Ferraris. Most preparations are relatively flat compared to
traditional preparations, with smooth and rounded internal line angles. Thick cusps
should be preserved in order to maximise the fracture resistance of the tooth.
If cusps that are too thick (>3.5 mm) are onlayed, this can increase the risk of
catastrophic failure. This was shown in the research by Fennis et al. in 2004, who
recommended that the placement of fiber in the dentin replacement layer can reduce
this risk.
- Preserving the BioRim and the Compression Dome Concept
The BioRim is defined as the 2-3 mm of tooth structure (enamel, DEJ/DEC and
superficial dentin) located above the CEJ.
Enamel is said to act as a compression dome, helping to transmit compressive forces to
dentin when a load is applied, and therefore reducing potentially damaging or catastrophic
tensile forces. The BioRim can be described as the base of the compression dome. By
removing the BioRim (e.g. by carrying out a traditional crown preparation), the compression
dome is disrupted and compressive forces directed from the occlusal portion of the tooth can
result in damaging tensile forces in the cervical area.
Fig.62
Clinical example of an overlay
preparation (left). Note that the BioRim
(marked in red) has been preserved
(right).

50. 49 | P a g e
You may see the coronal portion of the tooth referred to as the BioDome. For most indirect
Biomimetic restorations, the BioDome takes the form of a ceramic onlay or overlay which is
adhesively bonded to the preserved BioRim. A smooth preparation allows the restoration and
tooth to function well together in compression. Sharp corners or line angles should be
avoided in order to minimise the potentially catastrophic concentration of forces in these
areas. Standard engineering concepts should always be considering when restoring a tooth
biomimetically.
- Bonding Enamel Replacement to the Biobase
As per the previous lessons in the Six Lessons Approach to Biomimetic Restorative
Dentistry, the Peripheral Seal Zone (PSZ) should be achieved using appropriate Caries
Removal Endpoints (CRE) and Crack Removal Endpoints (CrRE). Once onlay
preparation is carried out, Immediate Dentin Sealing (IDS) and Resin Coating
(RC) should be performed, and 1 mm of fiber-reinforced composite placed. Together
with Deep Margin Elevation (DME), these elements form the Biobase.
After fabrication of an indirect or semi-direct restoration, the next step is to follow
gold-standard adhesive protocols in order to bond to the aforementioned Biobase.
As we are bonding to previously cured composite, the surface of the composite must
be treated before bonding. Air Abrasion (AA) or Air Particle Abrasion (APA) can be
used to expose unreacted double bonds within the composite surface structure. This
gives the potential for a strong chemical bond to form between the composite
resin Biobase and the composite resin-based cement, which is commonly heated
Fig.63
Note the smooth preparation with
rounded line angles and BioRim intact.

51. 50 | P a g e
restorative composite (e.g. heated AP-X from Kuraray). The resin cement is therefore
also bonded to the indirect or semi-direct composite or ceramic enamel replacement at
this same stage.
Example of Bonding Protocol
Bonding protocol depends on the materials used and the type of tooth/composite
structure being bonded to. An example bonding protocol is described below.
• Gold standard isolation protocol using rubber dam
• Air Abrasion of the Biobase using 29 micron Aluminium Oxide powder particles
• Application of 37% phosphoric acid for 30 seconds. Rinse for the same amount of
time and then air dry
• Surface treatment of the indirect/semi-direct restoration:
o Composite: Air Abrasion followed by 37% phosphoric acid for 30 seconds.
Rinse and dry
o Ceramic emax restoration: Suitable surface treatment using Hydrofluoric
acid, phosphoric acid, silanisation
• Uncured adhesive is placed on the Biobase and the intaglio surface of the
indirect/semi-direct restoration. As per previous steps in fabrication of the Biobase,
gold standard bonding agents such as Optibond FL or Clearfil SE Protect are
recommended
• Cementation using heated restorative composite (e.g. AP-X)
• Before curing, removal of excess resin cement using floss, PTFE tape, plastic
instruments, brushes. After curing, any remaining excess can be removed using a
number 12 blade or scaler.

52. 51 | P a g e
Cementation Using Heated Restorative Composite
In the example protocol above, heated restorative composite is used to ‘cement’ the
bonded indirect restoration. Benefits of using heated composite instead of dual-cure
resin cement include:
• As the composite is light-cured on command, this allows as much time as
necessary to ensure that the indirect restoration is correctly seated and all excess is
removed.
• The process of removing excess is much more predictable as the composite is in a
consistency which allows easy removal with plastic instruments, PTFE or floss.
• Improved mechanical and physical properties, including increased wear resistance
when compared to resin cements.
• As per the study by Gregor at al., appropriate levels of polymerization can be
achieved even through thick ceramic restorations. A robust light-curing protocol
should be followed and each surface of the restoration should be light-cured for an
appropriate amount of time (90 seconds per surface is suggested – consider
alternating between each surface to avoid overheating).
As with all techniques, if using heated restorative composite to bond an indirect
restoration, it is important to consider the possible limitations:
• The type of filler particle should be considered – micro-hybrid composites are
generally recommended.
• The degree of viscosity achieved upon heating can vary between different brands
of composite, and some composites may not achieve the desired viscosity for
cementation.
• The composite heating device should be able to heat the composite to an accurate,
reliable temperature and allow this temperature to be maintained – 68 degrees
Celsius for 10 minutes is generally recommended.
• Some composites may cool rapidly upon removal from the heating device, and the
viscosity may therefore increase to an unfavourable level.

53. 52 | P a g e
• Some composites may begin to polymerize if stored in the heating device for too
long.
An example of a restorative composite with favourable properties that is commonly used
for heated cementation is Clearfil AP-X by Kuraray.
Fig.64
Clinical example of overlay cementation
using heated restorative composite. From
left to right: (1) Biobase ready for
cementation. (2) Overlay fully seated and
cemented using heated restorative
composite, with excess visible. (3) Excess
restorative composite removed.

54. References
- Zafar MS, Amin F, Fareed MA, Ghabbani H,
Riaz S, Khurshid Z, Kumar N. Biomimetic
Aspects of Restorative Dentistry Biomaterials.
Biomimetics (Basel). 2020 Jul 15;5(3):34. doi:
10.3390/biomimetics5030034. PMID:
32679703; PMCID: PMC7557867.
- Goswami, Suchetana. (2018). Biomimetic
dentistry. Journal of Oral Research and
Review. 10. 28. 10.4103/jorr.jorr_3_17.
- Alleman D.S., Matthew A., Alleman D.S.
The Protocols of Biomimetic Restorative
Dentistry: 2002 to 2017. Increase the
longevity of restorations with the
biomimetic approach, Inside Dent. 13,
(2017).
- Alleman, David & Magne, Pascal. (2012). A
systematic approach to deep caries removal
end points: The peripheral seal concept in
adhesive dentistry. Quintessence international
(Berlin, Germany : 1985). 43. 197-208.
- Belli S, Erdemir A, Ozcopur M, Eskitascioglu
G. The effect of fibre insertion on fracture
resistance of root filled molar teeth with MOD
preparations restored with composite. Int
Endod J. 2005 Feb;38(2):73-80.
- Brannstrom M. The hydrodynamic theory of
dentinal pain: sensation in preparations, caries,
and the dentinal crack syndrome. J Endod.
1986 Oct;12(10):453-7.
- Kishen A, Vedantam S. Hydromechanics in
dentine: role of dentinal tubules and
hydrostatic pressure on mechanical stress-
strain distribution. Dent Mater. 2007
Oct;23(10):1296-306.
- Krell KV, Rivera EM. A six year evaluation of
cracked teeth diagnosed with reversible
pulpitis: treatment and prognosis. J Endod.
2007 Dec;33(12):1405-7.
- Larson TD, Douglas WH, Geistfeld RE. Effect
of prepared cavities on the strength of teeth.
Oper Dent. 1981;6(1):2-5.
- Magne P, Boff LL, Oderich E, Cardoso AC.
Computer-aided-design/computer-assisted-
manufactured adhesive restoration of molars
with a compromised cusp: effect of fiber-
reinforced immediate dentin sealing and cusp
overlap on fatigue strength. J Esthet Restor
Dent. 2012 Apr;24(2):135-46.
- Magne P, Oganesyan T. CT scan-based finite
element analysis of premolar cuspal deflection
following operative procedures. Int J
Periodontics Restorative Dent. 2009
Aug;29(4):361-9.
- Milicich G, Rainey JT. Clinical presentations
of stress distribution in teeth and the
significance in operative dentistry. Pract
Periodontics Aesthet Dent. 2000
Sep;12(7):695-700.
- Opdam NJ, Roeters JM. The effectiveness of
bonded composite restorations in the treatment
of painful, cracked teeth: six-month clinical
evaluation. Oper Dent. 2003 Jul-
Aug;28(4):327-33.
- Opdam NJ, Roeters JJ, Kuijs R, Burgersdijk
RC. Necessity of bevels for box only Class II
composite restorations. J Prosthet Dent. 1998
Sep;80(3):274-9.
- Opdam NJ, Roeters JJ, Loomans BA,
Bronkhorst EM. Seven-year clinical evaluation
of painful cracked teeth restored with a direct
composite restoration. J Endod. 2008
Jul;34(7):808-11.
- Politano G, Van Meerbeek B, Peumans M.
Nonretentive Bonded Ceramic Partial Crowns:
Concept and Simplified Protocol for Long-
lasting Dental Restorations. J Adhes Dent.
2018;20(6):495-510.
- Rainey JT. A sub-occlusal oblique transverse
ridge: identification of a previously unreported
tooth structure: the Rainey Ridge. J Clin
Pediatr Dent. 1996 Fall;21(1):9-13.
- Ratcliff S, Becker IM, Quinn L. Type and
incidence of cracks in posterior teeth. J
Prosthet Dent. 2001 Aug;86(2):168-72.
- Bijelic-Donova J, Garoushi S, Lassila LV,
Vallittu PK. Oxygen inhibition layer of
composite resins: effects of layer thickness and
surface layer treatment on the interlayer bond
strength. Eur J Oral Sci. 2015 Feb;123(1):53-
60.
- Hayashi J, Shimada Y, Tagami J, Sumi Y,
Sadr A. Real-Time Imaging of Gap Progress
during and after Composite Polymerization. J
Dent Res. 2017 Aug;96(9):992-9

55. - Jayasooriya PR, Pereira PN, Nikaido T,
Tagami J. Efficacy of a resin coating on bond
strengths of resin cement to dentin. J Esthet
Restor Dent. 2003;15(2):105-13; discussion
113.
- Lu H, Stansbury JW, Bowman CN. Towards
the elucidation of shrinkage stress
development and relaxation in dental
composites. Dent Mater. 2004
Dec;20(10):979-86.
- Magne P. Immediate dentin sealing: a
fundamental procedure for indirect bonded
restorations. J Esthet Restor Dent.
2005;17(3):144-54; discussion 155.
- Magne P, So WS, Cascione D. Immediate
dentin sealing supports delayed restoration
placement. J Prosthet Dent. 2007
Sep;98(3):166-74.
- Rueggeberg FA, Margeson DH. The effect of
oxygen inhibition on an unfilled/filled
composite system. J Dent Res. 1990
Oct;69(10):1652-8.
- Urabe I, Nakajima S, Sano H, Tagami J.
Physical properties of the dentin-enamel
junction region. Am J Dent. 2000
Jun;13(3):129-35.
- Van Meerbeek B, De Munck J, Mattar D, Van
Landuyt K, Lambrechts P. Microtensile bond
strengths of an etch&rinse and self-etch
adhesive to enamel and dentin as a function of
surface treatment. Oper Dent. 2003 Sep-
Oct;28(5):647-60.
- Van Meerbeek B, Peumans M, Poitevin A,
Mine A, Van Ende A, Neves A, De Munck J.
Relationship between bond-strength tests and
clinical outcomes. Dent Mater. 2010
Feb;26(2):e100-21.
- Bertischinger C, Paul SJ, Luthy H and Scharer
P, "Dual application of dentin bonding agents:
effect on bond strength," Am J Dent, vol. 9,
no. 3, pp. 115-119, 1996.
- Magne P, Kim TH, Cassione D and Donovan
TE, "Immediate dentin sealing improves bond
strengths of indirect restorations," J Prosthet
Dent, vol. 94, no. 6, pp. 511-519, 2005.
- Nikolaenko SA, Lohbauer U, Roggendorf M,
Petschelt A, Dasch W and Franenberberger R,
"Influence of C-Factor and layering technique
on microtensile bond strength to dentin,"
Dental Materials, vol. 20, no. 6, pp. 579-585,
2004.
- Giachetti L, Scaminaci Russo D, Bambi D and
Grandini R, "A review of polymerization
shrinkage stress: current techniques for
posterior direct resin restorations," J Contemp
Dent Pract, vol. 7, no. 4, pp. 79-88, 2006.
- Deliperi S and Bardwell D, "An alternative
method to reduce polymerization shrinkage
[stress] in direct posterior composite
restorations," J Amer Dent Assoc, vol. 133, no.
10, pp. 1387-1398, 2002.
- Dietschi D and Spreafico R, "Current clinical
concepts for adhesive cementation of tooth-
colored posterior restorations," PPAD, vol. 10,
no. 1, pp. 47-54, 1998.
- Belli S, Orucoglu H, Yildirim C and
Eskitascioglu G, "The Effect of Fiber
Placement or Flowable Resin Lining on
Microleakage in Class II Adhesive
Restorations," J Adhes Dent, vol. 9, no. 2, pp.
175-181, 2007.
- El-Mowafy O, El-Badrawy W, Eltanty A,
Abbasi K and Habib N, "Gingival
microleakage of class II resin composite
restorations with fiber inserts," Oper Dent, vol.
32, no. 3, pp. 298-305, 2007.
- Charton C, Colon P and Pla F, "Shrinkage
stress in light-cured composite resins:
Influence of material and photoactivation
mode," Dental Mater, vol. 23, no. 8, pp. 911-
920, 2007.
- Krejci I and Stavridakis M, "New perspectives
on dentin adhesion—differing methods of
bonding," Pract Periodontics Aesthet Dent,
vol. 12, no. 8, pp. 727-732, 2000.
- Jayoosariya PR, Pereira PNR, Nikaido T and
Tagami J, "fficacy of a resin coating on bond
strengths of resin cement to dentin," J Esthet
Restor Dent, vol. 15, no. 2, pp. 105-113, 2003.
- Pashley D, Tay F, Yui C, Hashimoto M,
Breschi L, Carvalho R and Ito S, "Collagen
degradation by host-derived enzymes during
aging," J Dent Res, vol. 83, no. 3, pp. 216-221,
2004.
- Br Dent J, Prevent and stop crack
propagation. 216, 542 (2014).
- Ivanisevic, Aljosa & Lainović, Tijana &
Blažić, Larisa & Marko, Vilotic. (2014).
Influence of Light-Curing Mode on the
Mechanical Properties of Dental Resin
Nanocomposites. Procedia Engineering. 69.
921-930. 10.1016/j.proeng.2014.03.071.
- Cubas, Gloria & Habekost, Luciano &
Camacho, Guilherme & Pereira-Cenci,
Tatiana. (2010). Fracture resistance of
premolars restored with inlay and onlay
ceramic restorations and luted with two
different agents. Journal of prosthodontic
research. 55. 53-9. 10.1016/j.jpor.2010.07.001.

56. - Bicalho AA, Pereira RD, Zanatta RF, Franco
SD, Tantbirojn D, Versluis A, Soares CJ.
Incremental filling technique and composite
material–part I: cuspal deformation, bond
strength, and physical properties. Oper Dent.
2014 Mar-Apr;39(2):E71-82.
- Bicalho AA, Valdívia AD, Barreto BC,
Tantbirojn D, Versluis A, Soares CJ.
Incremental filling technique and composite
material–part II: shrinkage and shrinkage
stresses. Oper Dent. 2014 Mar-Apr;39(2):E83-
92.
- Bresser RA, Gerdolle D, van den Heijkant IA,
Sluiter-Pouwels LMA, Cune MS, Gresnigt
MMM. Up to 12 years clinical evaluation of
197 partial indirect restorations with deep
margin elevation in the posterior region. J
Dent. 2019 Dec;91:103227.
- Deliperi S, Alleman D, Rudo D. Stress-
reduced Direct Composites for the Restoration
of Structurally Compromised Teeth: Fiber
Design According to the “Wallpapering”
Technique. Oper Dent. 2017
May/Jun;42(3):233-243.
- Feilzer AJ, De Gee AJ, Davidson CL. Setting
stress in composite resin in relation to
configuration of the restoration. J Dent Res.
1987 Nov;66(11):1636-9.
- Fennis WM, Kuijs RH, Kreulen CM,
Verdonschot N, Creugers NH. Fatigue
resistance of teeth restored with cuspal-
coverage composite restorations. Int J
Prosthodont. 2004 May-Jun;17(3):313-7.
- Magne P, Spreafico R. Deep Margin
Elevation: A Paradigm Shift. Am J Esthet Dent
2012; 2(2).
- Sarfati A, Tirlet G. Deep margin elevation
versus crown lengthening: biologic width
revisited. Int J Esthet Dent. 2018;13(3):334-
356.
- Asmussen E, Peutzfeldt A. The effect of
secondary curing of resin composite on the
adherence of resin cement. J Adhes Dent. 2000
Winter;2(4):315-8.
- Besek M, Mörmann WH, Persi C, Lutz F. Die
Aushärtung von Komposit unter Cerec-Inlays
[The curing of composites under Cerec inlays].
Schweiz Monatsschr Zahnmed.
1995;105(9):1123-8.
- Carvalho RM, Santiago SL, Fernandes CA,
Suh BI, Pashley DH. Effects of prism
orientation on tensile strength of enamel. J
Adhes Dent. 2000 Winter;2(4):251-7.
- Fennis WM, Tezvergil A, Kuijs RH, Lassila
LV, Kreulen CM, Creugers NH, Vallittu PK.
In vitro fracture resistance of fiber reinforced
cusp-replacing composite restorations. Dent
Mater. 2005 Jun;21(6):565-72.
- Ferraris F. Posterior indirect adhesive
restorations (PIAR): preparation designs and
adhesthetics clinical protocol. Int J Esthet
Dent. 2017;12(4):482-502.
- Gregor L, Bouillaguet S, Onisor I, Ardu S,
Krejci I, Rocca GT. Microhardness of light-
and dual-polymerizable luting resins
polymerized through 7.5-mm-thick
endocrowns. J Prosthet Dent. 2014
Oct;112(4):942-8.
- Gresnigt MMM, Özcan M, Carvalho M, Lazari
P, Cune MS, Razavi P, Magne P. Effect of
luting agent on the load to failure and
accelerated-fatigue resistance of lithium
disilicate laminate veneers. Dent Mater. 2017
Dec;33(12):1392-1401.
- Krämer N, Frankenberger R. Clinical
performance of bonded leucite-reinforced glass
ceramic inlays and onlays after eight years.
Dent Mater. 2005 Mar;21(3):262-71.
- Magne P, Belser UC. Rationalization of shape
and related stress distribution in posterior
teeth: a finite element study using nonlinear
contact analysis. Int J Periodontics Restorative
Dent. 2002 Oct;22(5):425-33.
- Milicich G. The compression dome concept:
the restorative implications. Gen Dent. 2017
Sep-Oct;65(5):55-60.
- Van den Breemer CRG, Buijs GJ, Cune MS,
Özcan M, Kerdijk W, Van der Made S,
Gresnigt MMM. Prospective clinical
evaluation of 765 partial glass-ceramic
posterior restorations luted using photo-
polymerized resin composite in conjunction
with immediate dentin sealing. Clin Oral
Investig. 2021 Mar;25(3):1463-1473.

57. - Wang RZ, Weiner S. Strain-structure relations
in human teeth using Moiré fringes. J
Biomech. 1998 Feb;31(2):135-41.
- Geurtsen W, Schwarze T, Günay H. Diagnosis,
therapy, and prevention of the cracked tooth
syndrome. Quintessence Int. 2003
Jun;34(6):409-17.