## 5 Conclusions  
Based on the reported results and within the limitation of this investigation, the following conclusions can be reported:  
* Temperature peaks and temperature rates measured in the core of flowable bulk-fill composites are significantly higher (\(p<0.05\)) than those measured for packable bulk-fill composites.
* The type of initiator system affects both the temperature rise and rate; a significantly higher temperature rate (\(p<0.05\)) has been measured for EVF, suggesting faster polymerization kinetics.
* For the bulk-fill technique, temperature rise levels are below 11 \({}^{\circ}\)C; however, no significant difference in the mean values of temperature rise has been observed among the investigated bulk-fill RBCs.
* For the bulk-fill techniques, the light curing modality (1000 mW/cm\({}^{2}\) for 20 s) can be considered safe for the integrity of the pulp tissue, if the thickness of the occlusal dentin, spacing the restorative material from the pulp chamber, is not lower than 1 mm.
* For the bulk-fill technique, temperature rise levels are below 13 \({}^{\circ}\)C. Temperature rates measured for the flowable RBCs are significantly higher (\(p<0.05\)) than those measured for the packable RBCs. The temperature rise measured for EVF is significantly higher (\(p<0.05\)) than SFL.
* As far as flowable bulk-fill RBCs in conjunction with the incremental layering technique are concerned, a curing modality lower than 1000 mW/cm\({}^{2}\) is recommended, especially if the thickness of the occlusal dentin, spacing the restorative material from the pulp chamber, is lower than 1 mm.
* Finally, the results that we have observed with the halogen curing unit may be extendable to the LED curing units incorporating a variety of semiconductors: a blue LED and a violet LED. This approach will be implemented in our future investigations.
* The clinical operator should avoid the use of high level of light intensity for curing flow composites applied through the incremental technique in very deep cavities close to the pulp chamber. In these cases, a reduced light intensity in conjunction with an increased exposure time of the light source is recommended. The bulk-fill technique can be used safely without fear of causing thermal damage to the dental pulp.  
**Author Contributions:** Conceptualization, R.D.S. and S.R.; methodology, V.L.; software, C.R.; validation, S.R., R.D.S. and A.V.; formal analysis, C.R.; investigation, V.G.; resources, S.R.; data curation, R.D.S.; writing--original draft preparation, R.D.S., V.G. and V.L.; writing--review and editing, R.D.S., V.G. and V.L.; visualization, A.V.; supervision, S.R.; project administration, A.V.; funding acquisition, S.R. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This work was financially supported by the PON 03 PE_00110_1/ptd1_000410. Title: Sviluppodimanotecnologie orientate alla rigenerazione e ricostruzione tissutale, implantologia e sensoristica inodontoiatriia/oculistica (SORRISO).  
**Acknowledgments:** We thank [PERSON] and [PERSON] for providing Kerr and Ivoclar composite materials.  
**Conflicts of Interest:** The authors do not have any financial interest in the companies whose materials are included in this article. This study was approved by the Ethics Committee of the University of Naples Federico II, with protocol number 137-2017.