Light-curing units used in dentistry: factors associated with heat development-potential risk for patients.
OBJECTIVE
To investigate how heat development in the pulp chamber and coronal surface of natural teeth with and without cusps subjected to irradiance using light-emitting diode (LED)-light-curing units (LCUs) is associated with (i) irradiance, (ii) time, (iii) distance, and (iv) radiant exposure.


METHODS
Three different LED-LCUs were used. Their irradiance was measured with a calibrated spectrometer (BlueLight Analytics Inc., Halifax, Canada). An experimental rig was constructed to control the thermal environment of the teeth. The LED-LCU tip position was accurately controlled by a gantry system. Tooth surface temperature was measured by thermography (ThermaCAM S65 HS, FLIR Systems, Wilsonville, USA) and pulp chamber temperature with a thermocouple. LED-LCU tip distance and irradiation times tested were 0, 2, and 4 mm and 10, 20, and 30 s, respectively. Ethical permission was not required for the use of extracted teeth.


RESULTS
Maximum surface and pulp chamber temperatures were recorded in tooth without cusps (58.1 °C  ± 0.9 °C and 43.1 °C ± 0.9 °C, respectively). Radiant exposure explained the largest amount of variance in temperature, being more affected by time than irradiance.


CONCLUSIONS
At all combinations of variables tested, repeated measurements produced consistent results indicating the reliability of the method used. Increased exposure time seems to be the factor most likely to cause tissue damage.


CONCLUSIONS
Risk of superficial tissue damage at irradiances >1200 mW/cm2is evident. There is a risk of pulp damage when only thin dentin is left at higher irradiances (>1200 mW/cm2). Clinicians should be aware of LED-LCU settings and possible high temperature generated.
Department for Clinical Dentistry/Faculty of Health Sciences, The Arctic University of Norway (UIT), Tromsø, Norway.
Mathieu
M
Mouhat
Department of Medical Biology/Faculty of Health Sciences, The Arctic University of Norway (UIT), Tromsø, Norway.
James
J
Mercer
Department for Clinical Dentistry/Faculty of Health Sciences, The Arctic University of Norway (UIT), Tromsø, Norway.
Lina
L
Stangvaltaite
Department for Clinical Dentistry/Faculty of Health Sciences, The Arctic University of Norway (UIT), Tromsø, Norway. ulf.ortengren@uit.no.|Department of Cariology, Institute of Odontology/Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. ulf.ortengren@uit.no.
Ulf
U
Örtengren
D055117:Curing Lights, Dental; D003786:Dental Pulp Cavity / Q000528:radiation effects; D006358:Hot Temperature; D006801:Humans; D066298:In Vitro Techniques; D008964:Molar, Third; D061214:Patient Safety; D015203:Reproducibility of Results; D012307:Risk Factors; D013817:Thermography / Q000379:methods*
Curing lights; Dentistry; Light; Temperature; Tooth
Dent Mater. 2015 May;31(5):583-93
25804190
Acta Odontol Scand. 2014 Jan;72(1):36-41
23638766
Oper Dent. 2010 May-Jun;35(3):353-61
20533637
Dent Mater. 2014 Dec;30(12 ):1345-57
25460008
J Dent. 2013 May;41(5):455-63
23416195
J Contemp Dent Pract. 2009 Jan 01;10(1):17-24
19142252
J Can Dent Assoc. 2011;77:b9
21507291
Am J Orthod Dentofacial Orthop. 2010 Mar;137(3):379-83
20197176
Oper Dent. 2014 Jan-Feb;39(1):4-14
23786585
Oper Dent. 2006 Mar-Apr;31(2):261-5
16827031
Oper Dent. 2013 May-Jun;38(3):324-33
23092145
Open Dent J. 2008 Dec 05;2:137-41
19444316
Oral Surg Oral Med Oral Pathol. 1965 Apr;19:515-30
14263662
J Oral Rehabil. 1998 Dec;25(12):908-13
9888225
Gen Dent. 2012 Jul-Aug;60(4):e210-4
22782053
Dent Mater. 2012 Dec;28(12 ):1240-9
23018083
Int J Paediatr Dent. 2009 Jan;19(1):48-54
18298542
Oper Dent. 2016 Jul-Aug;41(4):397-408
26652017
J Dent Res. 2015 Sep;94(9):1179-86
26156516
Oper Dent. 2010 Mar-Apr;35(2):220-30
20420066
Oper Dent. 2004 May-Jun;29(3):287-94
15195729
J Esthet Dent. 2000;12(6):320-7
14743527
J Oral Rehabil. 1997 Nov;24(11):791-801
9426160
Oper Dent. 2008 May-Jun;33(3):325-31
18505224
Dent Mater J. 2014;33(6):764-9
25311340
Quintessence Int. 2003 Jan;34(1):71-5
12674362
Dent Mater. 2015 Feb;31(2):93-104
25483935
J Biomed Mater Res B Appl Biomater. 2005 Feb 15;72(2):254-9
15497167
J Biomed Mater Res B Appl Biomater. 2005 Feb 15;72(2):260-7
15455367
Dent Mater. 1999 Jul;15(4):275-81
10551096
J Appl Oral Sci. 2009 Jul-Aug;17(4):289-93
19668987
Prim Dent Care. 2008 Jan;15(1):33-8
18198059
Clin Oral Investig. 2009 Sep;13(3):309-16
19085020
Eur J Prosthodont Restor Dent. 2012 Jun;20(2):50-5
22852519
J Oral Rehabil. 2005 May;32(5):362-7
15842246