Journal club Presenation on topic Preheated bulk fill composite temperature on Intrapulpal temperature An In Vitro study

1. Effect Of Preheated Bulk-fill Composite
Temperature On
Intrapulpal Temperature Increase
A In Vitro Study
JOURNAL CLUB PRESENTATION
Presented by,
Dr. Himani
Thawale

2. INTRODUCTION
• Dental practitioners often have difficulty in adapting
and contouring composites to cavities because of the
high viscosity of paste-like composites.
• Preheating is a method that decreases composite
viscosity & results in better adaptation and better
wettability of the prepared cavity wall, reducing
microleakage.
Wagner WC, Aksu MN, Neme AM, Linger JB, Pink FE, Walker S. Effect of pre-heating resin composite on
restoration microleakage. Oper Dent. 2008;33:72-78.

3.  In addition, the increased polymerization temperature increases both
radical and monomer mobility, leading to a higher overall conversion .
 Manufacturers have developed a heating device for clinical use (Calset;
AdDent Inc, Danbury, Connecticut) that preheats composite compules
to specific temperatures.
 To use such a device, the practitioner merely removes a heated
compule loaded into a syringe and injects the contents directly into the
preparation.
Friedman J. Heating assembly for preheating dental materials. US Patent. 2001;6(236):020.

4. .
• There are many alternative methods of preheating including the use of a dental unit light,
hand-holding, hot water bath, thermocycling apparatus, microwave oven, dry oven, wax
warmer, and hair dryer.
• The flow of commercial composites can be greatly increased during preheating.
• However, the amount of flow varies between brands and composite classes, and the fluidity
of the heated composite never reaches the low levels as that of a flowable composite at room
temperature.

5. • The temperature at which the composite is exposed during preheating in the
above device is between 50C and 70C, which is well tolerated during normal
daily activities by healthy teeth and the surrounding mucous membranes.
• The temperature of the composite decreases immediately after the composite
compule is injected into the cavity after removal from the heating device.
• Nevertheless, pulp temperature can increase resulting in iatrogenic damage to
the pulp.
Daronch M, Rueggeberg FA, Moss L, de Goes MF. Clinically relevant issues related to pre-heating composites. J Esthet Restor Dent.
2006; 18:340-351

6. • An increase in pulp temperature may be affected by
- Remaining dentin thickness
- Cavity preparation
- Type of the composite.
• Therefore, knowledge of the increased temperature and the rate of such increase in the
pulp chamber are critical in anticipating the potential clinical problems associated with
the use of the abovementioned clinical device.

7. • Dental pulp is a highly vascularized tissue whose vitality may be compromised during tooth
preparation and clinical restoration.
• The normal pulp temperature is between 34C and 35C.
• The classic animal study by Zach and Cohen identified a threshold temperature for irreversible
pulp damage when external heat was applied to a healthy tooth; an intrapulpal temperature
increase of
5.5C induced necrosis in 15% of the pulps tested;
11C induced necrosis in 60% of the pulps, and an increase of
16C induced necrosis in 100% of the pulps with irreversible pulp damage.
Zach L, Cohen G. Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol.
1965;19:515-530.

8. • Intrapulpal temperature can increase due to several reasons
- Including High-speed Handpieces,
- Exothermic Reactions Of Composites & Acrylics.
• Mechanisms causing damage to the pulp include
Protoplasmic coagulation or dilatation of the fluid in the dentinal tubules & pulp
Leads to increased outward flow from the tubules,
vascular injury & Tissue necrosis.

9. • Another reason for intrapulpal temperature increase is the photopolymerization
process.
• This can cause an increase in intrapulpal temperature up to 20C, depending on the
process of tooth preparation, the photoactivation protocol, and the material used.
• The type of light-curing unit, power density, exposure duration, the distance between
the tooth and/or the composite surface and the tip end of the light guide, composite
shade, and thickness can all affect intra-pulpal temperature increase.

10. PRIMARY HYPOTHESIS
Preheated Composites Increase Intra-pulpal Temperature In Class II (MOD)
Cavities That Cannot Be Accepted Literally

11. The Present Study Measures The In Vitro
Intrapulpal Temperature Increase When
Placing Room Temperature Or Preheated (54c
And60c) Bulk-fill Composites
AIM

12. Materials
&
Methods
• The research protocol used was approved by the institutional
ethics committee of the relevant university.
• Extracted human lower third molars were selected and
class II (MOD) cavities in each tooth were prepared, resulting
in a remaining dentin thickness of 1 mm

13. •Mesial and distal box cavity was standardized to an occluso-
gingival depth of 5 mm, occlusal box depth was prepared with
remaining dentin thickness of 1 mm.
Soft tissue residues on the teeth were cleaned by brushing under
running water.
The root of each tooth was cut with a bur and the pulp was
removed using K and H files, irrigated with saline, and enlarged.

14. A plastic cup was cut in the middle, filled with 37C of water, and covered by wax.
The tooth was inserted into the wax and contacted with water.
K-type thermocouple (PM6501; Peakmeter, PRC) was placed at the pulp chamber
in the prepared root canal and fixed with a gingival barrier (Opaldam; Ultradent)
To achieve standardization, radiography was performed for every sample

15. Thirty teeth were randomly selected and divided into three groups
GROUP-I
(n= 10)
Restored with a
bulk-fill composite
(Filtek bulk-fill
posterior)
GROUP-II
(n= 10)
Restored with
Preheated bulk-fill
composite at 54 c
GROUP-III
(n= 10)
Restored with
Preheated bulk-fill
composite at 60 c
1 2 3

16. In the first group, teeth were placed in a 37 C bath which
simulated human body temperature.
The automatrix (the SuperMat Universal Dental Matrix, Kerr,
Switzerland) was used for every restoration.
Teeth were restored with a bulk-fill composite (Filtek bulk-fill
posterior [3M-ESPE], Saint Paul, Minnesota) that was stored at
room temperature
For curing, a 1200 mW/cm2 LED light curing unit (Monitex
_lndustrial Co Ltd, Taiwan) was used
Light curing was applied for 10 seconds at the occlusal surface, 10
seconds at the lingual surface, and 10 seconds at the buccal surface
separately for each box cavity as per the manufacturer's
recommendation.

18. • Temperature increases above those of the physiological baseline occurring after the
composite was injected into the class II (MOD) preparation was identified, and the
millivolt values associated with the
- Initiation (START_FILL)
- Completion of composite insertion (END_FILL) were recorded.
- After contouring (FINISH_CONTOUR),
- Immediately before light curing (START_LIGHT_CURE)
- After switching off the hardener (END_LIGHT_CURE),
An additional reading was obtained.

19. Teeth in the second and third groups were also processed using
the same protocol as mentioned above with a single change,
which was inclusion of a preheating step..
The composites
were preheated in an
oven for 15 minutes
at 54 C
And then the
compules were
applied to the
cavities
immediately
Group
II The composites
were preheated in
an oven for 15
minutes at 60C
And then the
compules were
applied to the
cavities
immediately.
Group
III
The obtained values were recorded as mentioned above

20. RESULT

21. Graph -1 Representative time-based profiles of intrapulpal temperature
change during restorative procedures
Composite Temperature
Room Temperature
54 C
60 C

22. The mean intrapulpal temperature values of the applied composite
restorative materials are shown
Table 1- Intrapulpal Heat Temperature

23. Stage, composite temperature, and stage composite temperature interaction significantly
affected the intrapulpal temperature values(P< .001).
There were significant differences between all restoration stage values in all composite
temperature groups (P < .05) except at the finish contouring and the start_light_cure stages.
There was no significant difference between the finish contouring and the start light-cure
stages in any of the composite temperature groups (P > .05).
There was no significant difference between the 54C and 60C composite temperature
groups at any of the restoration stages (P > .05).

24. There were significant differences between the 22C and 60C composite temperature
groups at all the restoration stages (P < .05).
There were significant differences between the 22C and 54C composite temperature
groups at all the restoration stages (P < .05) except at the star_fill stage (baseline
stage) (P > .05).

25. DISCUSSION

26. • The hypothesis is that preheated composites increase intrapulpal temperature in
class II (MOD) cavities that cannot be accepted literally based on our results.
• Both preheated composite groups showed higher intrapulpal temperatures than
the room temperature group at all restorative stages, with statistically significant
differences.
• Composite preheating increased intrapulpal temperature, but this was not
sufficient to cause injury to the pulp.

27. • Zack and Cohen's study showed that the threshold temperature increase
resulting in injury is 5.5C, with the average intrapulpal temperature increase
being higher than 5.5C in all groups.
• All previous data have indicated that the preheating procedure was not the
only factor in intrapulpal temperature increase.
• Dentin thickness, type of composite, cavity preparation, and application of
curing light are also likely to affect intra pulpal temperature.
Zach L, Cohen G. Pulp response to externally applied heat. Oral Surg Oral Med Oral Pathol.
1965;19:515-530

28. • Daronch et al. 2006 Reported that composite temperature quickly decreased when
the compule was removed from the heating device, resulting in no harm to the pulp.
• The present study yielded a similar result, with preheating increasing intrapulpal
temperature but not causing pulp injury.
• The study confirms that the biggest risk for pulp health occurs during
polymerization. Daronch et al. also found that application of the curing light
increased intrapulpal temperature by more than 5C.
Journal of Esthetic and Restorative Dentistry, 18(6), 340–350.2006

29. • Another factor that determines the intrapulpal temperature increase is the remaining
thickness of the dentin.
• In the present study, the remaining dentin has been sufficiently isolated around the pulp
chamber against heat build up by applying a preheated composite, but not by light curing.
• The remaining dentin thickness between the pulp floor or axial wall and the pulp chamber
appears to be one of the most important factors for the protection of the pulp since dentin
acts as a thermal barrier against harmful stimuli.
• As result, the more the remaining dentin thickness implies the greater the protection of the
pulp.
Nomoto R, McCabe JF, Hirano S. Comparison of halogen, plasma and LED curing units.
Oper Dent. 2004;29:287-294.

30. • Yasa et al. 2017 also conducted a study and found that bulk-fill composites
affect intrapulpal temperature. Their study showed that light curing bulk-fill
composites lead to a higher temperature increase.
• In their study, a Filtek bulk-fill posterior showed maximum temperature
change values of 11.59C without preheating.
• In their study, specimens were prepared with 0.5 mm remaining dentin
thickness, and this may have led to a larger temperature change.
• This is a factor to consider when studying bulk-fill composites cause pulp
damage via intra-pulpal temperature increase

31. • El-Deeb et al.2015 , reported that a preheated silorane-based resin composite
(Filtek LS [Shade A3, 3M ESPE], Saint Paul, Minnesota) applied to cavities
caused an increase in intrapulpal temperature, which did not exceed the threshold
temperature
J Adv Res. 2015 May;6(3):471-478

32. • Tauböck et al. 2015 also found that preheating improves the mechanical
properties of composites, with decreased viscosity and increased flowability,
thus making their adaptation and contouring easier.
• Preheating improves material-handling characteristics and marginal
adaptation, and reduces microleakage.
• All these features are very important for clinical usage, and benefits of
improved material features are desirable to practitioners.
• However, this method should be used considering possible damage to the
pulp.
Tauböck TT, Tarle Z, Marovic D, Attin T. Pre-heating of high-viscosity bulk-fill resin composites : effects on shrinkage
force and monomer conversion. J Dent. 2015Nov;43(11):1358-1364. https://doi.org/10. 1016/j.jdent.2015.07.014.

33. LIMITATION
• Pulp is a highly vascularized connective tissue with an intrapulpal blood
stream.
• Trowbridge et al. and Baldissara et al. showed that normal pulp temperature is
between 34C and 35 C, with the blood stream playing a balancing role in
maintaining this temperature.
• In the present study, a 37C temperature was used instead of an in vivo model
representing physiological temperature.
• Furthermore, the basin did not have any blood stream and this has been a
limitation of the study.

34. • Nevertheless, the effect of preheated composite application needs to be verified
invivo. Calset is a heating device used for preheating composites. In the present
study, an oven was used for preheating.
• However, it has been a limitation but as such there are no major differences
between the Calset and the oven that we used, and their working principles are
similar.
• The bonding agent application may decrease the heat transfer under clinical
conditions.
• But, a previous study reported that there was no significant difference in the pulpal
temperature increase with and without the application of a dentin-bonding agent.

35. • The current study was performed at room temperature under laboratory
conditions, using a bath without fluid motion in the dentinal tubules and the
surrounding periodontal tissues.
• The surrounding periodontal tissues could also promote heat convection under
clinical conditions, limiting the intrapulpal temperature change.
• Therefore, further studies are necessary to evaluate the effects of these
limitation results on this study.

36. CONCLUSION

37. • Our study found that within the limitations of an in vitro study,
preheating does not represent a significant problem in terms of
intrapulpal temperature increase.
• Even if the preheating process results in increases with the increase
of intrapulpal temperature, this temperature increase is not the
critical factor that causes harm to the pulp.
• However, possibility of pulpal damage caused by increase in
temperature should be considered when using light-cured
preheated bulk-fill materials in very deep cavities.

38. THANK YOU