Effect of pulse-width-modulated LED light on the temperature change of composite in tooth cavities

Seol Ah Jo, Chang Ha Lee, Min Jung Kim, Jack Ferracane, In Bog Lee

Research output: Contribution to journalArticle

Abstract

Objective: The purpose of this study was to investigate the effects of the radiant emittance and cure time of pulse width modulation (PWM)-controlled LED light on the temperature change of composite and dentin. Methods: Class I cavities (M-D 6 mm, B-L 4 mm, Depth 2.5 mm) were prepared on 30 extracted human molars and vertically sectioned to expose the mesial side of the cavity and tooth. Cavities were filled with Bulk Fill Posterior Restorative (BFP, 3M ESPE) and cured with an LED light. The duty ratio (% of time the light is on) and cure time of the LED light were controlled using an Arduino UNO microcontroller (PWM) as follows (6 groups, n = 5): 10%/100 s, 30%/33.3 s, 50%/20 s, 100%/10 s, Increase mode (0 → 100%)/20 s, and Decrease mode (100 → 0%)/20 s. All measurements were performed at 100 Hz PWM with the constant total radiant exposure. Thermograms of the specimens were recorded using an infrared thermal camera (VarioCamhr head 700, InfraTec GmbH) for a pre-cure time of 20 s, cure time, and a post-cure time of 100 s at room temperature of 30 ± 0.5 °C. Temperature change data on the composite and dentin surfaces were collected at incremental distances of 0.625 mm and 1 mm from the top of the cavity to the pulp. Data were statistically analyzed using two-way ANOVA and Tukey's post-hoc test at α = 0.05. Results: A rapid temperature increase occurred within the cavity during light curing. The maximum temperature rises (ΔTmax) were observed at 0.625 mm apical from the top and middle of the cavity. The ΔTmax ranged from 7.62 to 16.74 °C at 0.625 mm apical from the top, 4.83 to 11.39 °C at the floor of the cavity, and 3.16 to 8.09 °C in the dentin 1 mm beneath the cavity base. The ΔTmax of composite and dentin increased and the time to reach ΔT = 5 °C decreased with increasing duty ratio at constant radiant exposure. In the Increase mode, ΔTmax was lower than that of 50%/20 s mode. The ΔTmax in the Decrease mode was similar to that of 100%/10 s mode. Significance: The PWM-LED curing light system controlled by a microcontroller provided a useful tool of varying the radiant emittance and cure time with constant radiant exposure to evaluate temperature change of composite and dentin. These result will be helpful to determine proper curing modes with varying radiant emittance of the LED curing light for decreasing temperature change of composite and dentin. At constant radiant exposure and cure times, the Increase mode showed lower and slower temperature rises than the 50%/20 s and Decrease mode. Within the limitations of this in vitro study, when radiant exposure is constant, a curing light with lower radiant emittance can induce relatively low thermal transfer, thereby decreasing the risk of pulpal damage.

Original languageEnglish (US)
JournalDental Materials
DOIs
StateAccepted/In press - Jan 1 2019

Fingerprint

Light emitting diodes
Tooth
Dentin
Light
Temperature
Curing
Composite materials
Pulse width modulation
Microcontrollers
Hot Temperature
Analysis of variance (ANOVA)
Pulp
Cameras
Analysis of Variance
Infrared radiation
Head

Keywords

  • Composite
  • Infrared thermal camera
  • LED curing light
  • Pulse width modulation (PWM)
  • Temperature change

ASJC Scopus subject areas

  • Materials Science(all)
  • Dentistry(all)
  • Mechanics of Materials

Cite this

Effect of pulse-width-modulated LED light on the temperature change of composite in tooth cavities. / Jo, Seol Ah; Lee, Chang Ha; Kim, Min Jung; Ferracane, Jack; Lee, In Bog.

In: Dental Materials, 01.01.2019.

Research output: Contribution to journalArticle

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abstract = "Objective: The purpose of this study was to investigate the effects of the radiant emittance and cure time of pulse width modulation (PWM)-controlled LED light on the temperature change of composite and dentin. Methods: Class I cavities (M-D 6 mm, B-L 4 mm, Depth 2.5 mm) were prepared on 30 extracted human molars and vertically sectioned to expose the mesial side of the cavity and tooth. Cavities were filled with Bulk Fill Posterior Restorative (BFP, 3M ESPE) and cured with an LED light. The duty ratio ({\%} of time the light is on) and cure time of the LED light were controlled using an Arduino UNO microcontroller (PWM) as follows (6 groups, n = 5): 10{\%}/100 s, 30{\%}/33.3 s, 50{\%}/20 s, 100{\%}/10 s, Increase mode (0 → 100{\%})/20 s, and Decrease mode (100 → 0{\%})/20 s. All measurements were performed at 100 Hz PWM with the constant total radiant exposure. Thermograms of the specimens were recorded using an infrared thermal camera (VarioCamhr head 700, InfraTec GmbH) for a pre-cure time of 20 s, cure time, and a post-cure time of 100 s at room temperature of 30 ± 0.5 °C. Temperature change data on the composite and dentin surfaces were collected at incremental distances of 0.625 mm and 1 mm from the top of the cavity to the pulp. Data were statistically analyzed using two-way ANOVA and Tukey's post-hoc test at α = 0.05. Results: A rapid temperature increase occurred within the cavity during light curing. The maximum temperature rises (ΔTmax) were observed at 0.625 mm apical from the top and middle of the cavity. The ΔTmax ranged from 7.62 to 16.74 °C at 0.625 mm apical from the top, 4.83 to 11.39 °C at the floor of the cavity, and 3.16 to 8.09 °C in the dentin 1 mm beneath the cavity base. The ΔTmax of composite and dentin increased and the time to reach ΔT = 5 °C decreased with increasing duty ratio at constant radiant exposure. In the Increase mode, ΔTmax was lower than that of 50{\%}/20 s mode. The ΔTmax in the Decrease mode was similar to that of 100{\%}/10 s mode. Significance: The PWM-LED curing light system controlled by a microcontroller provided a useful tool of varying the radiant emittance and cure time with constant radiant exposure to evaluate temperature change of composite and dentin. These result will be helpful to determine proper curing modes with varying radiant emittance of the LED curing light for decreasing temperature change of composite and dentin. At constant radiant exposure and cure times, the Increase mode showed lower and slower temperature rises than the 50{\%}/20 s and Decrease mode. Within the limitations of this in vitro study, when radiant exposure is constant, a curing light with lower radiant emittance can induce relatively low thermal transfer, thereby decreasing the risk of pulpal damage.",
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TY - JOUR

T1 - Effect of pulse-width-modulated LED light on the temperature change of composite in tooth cavities

AU - Jo, Seol Ah

AU - Lee, Chang Ha

AU - Kim, Min Jung

AU - Ferracane, Jack

AU - Lee, In Bog

PY - 2019/1/1

Y1 - 2019/1/1

N2 - Objective: The purpose of this study was to investigate the effects of the radiant emittance and cure time of pulse width modulation (PWM)-controlled LED light on the temperature change of composite and dentin. Methods: Class I cavities (M-D 6 mm, B-L 4 mm, Depth 2.5 mm) were prepared on 30 extracted human molars and vertically sectioned to expose the mesial side of the cavity and tooth. Cavities were filled with Bulk Fill Posterior Restorative (BFP, 3M ESPE) and cured with an LED light. The duty ratio (% of time the light is on) and cure time of the LED light were controlled using an Arduino UNO microcontroller (PWM) as follows (6 groups, n = 5): 10%/100 s, 30%/33.3 s, 50%/20 s, 100%/10 s, Increase mode (0 → 100%)/20 s, and Decrease mode (100 → 0%)/20 s. All measurements were performed at 100 Hz PWM with the constant total radiant exposure. Thermograms of the specimens were recorded using an infrared thermal camera (VarioCamhr head 700, InfraTec GmbH) for a pre-cure time of 20 s, cure time, and a post-cure time of 100 s at room temperature of 30 ± 0.5 °C. Temperature change data on the composite and dentin surfaces were collected at incremental distances of 0.625 mm and 1 mm from the top of the cavity to the pulp. Data were statistically analyzed using two-way ANOVA and Tukey's post-hoc test at α = 0.05. Results: A rapid temperature increase occurred within the cavity during light curing. The maximum temperature rises (ΔTmax) were observed at 0.625 mm apical from the top and middle of the cavity. The ΔTmax ranged from 7.62 to 16.74 °C at 0.625 mm apical from the top, 4.83 to 11.39 °C at the floor of the cavity, and 3.16 to 8.09 °C in the dentin 1 mm beneath the cavity base. The ΔTmax of composite and dentin increased and the time to reach ΔT = 5 °C decreased with increasing duty ratio at constant radiant exposure. In the Increase mode, ΔTmax was lower than that of 50%/20 s mode. The ΔTmax in the Decrease mode was similar to that of 100%/10 s mode. Significance: The PWM-LED curing light system controlled by a microcontroller provided a useful tool of varying the radiant emittance and cure time with constant radiant exposure to evaluate temperature change of composite and dentin. These result will be helpful to determine proper curing modes with varying radiant emittance of the LED curing light for decreasing temperature change of composite and dentin. At constant radiant exposure and cure times, the Increase mode showed lower and slower temperature rises than the 50%/20 s and Decrease mode. Within the limitations of this in vitro study, when radiant exposure is constant, a curing light with lower radiant emittance can induce relatively low thermal transfer, thereby decreasing the risk of pulpal damage.

AB - Objective: The purpose of this study was to investigate the effects of the radiant emittance and cure time of pulse width modulation (PWM)-controlled LED light on the temperature change of composite and dentin. Methods: Class I cavities (M-D 6 mm, B-L 4 mm, Depth 2.5 mm) were prepared on 30 extracted human molars and vertically sectioned to expose the mesial side of the cavity and tooth. Cavities were filled with Bulk Fill Posterior Restorative (BFP, 3M ESPE) and cured with an LED light. The duty ratio (% of time the light is on) and cure time of the LED light were controlled using an Arduino UNO microcontroller (PWM) as follows (6 groups, n = 5): 10%/100 s, 30%/33.3 s, 50%/20 s, 100%/10 s, Increase mode (0 → 100%)/20 s, and Decrease mode (100 → 0%)/20 s. All measurements were performed at 100 Hz PWM with the constant total radiant exposure. Thermograms of the specimens were recorded using an infrared thermal camera (VarioCamhr head 700, InfraTec GmbH) for a pre-cure time of 20 s, cure time, and a post-cure time of 100 s at room temperature of 30 ± 0.5 °C. Temperature change data on the composite and dentin surfaces were collected at incremental distances of 0.625 mm and 1 mm from the top of the cavity to the pulp. Data were statistically analyzed using two-way ANOVA and Tukey's post-hoc test at α = 0.05. Results: A rapid temperature increase occurred within the cavity during light curing. The maximum temperature rises (ΔTmax) were observed at 0.625 mm apical from the top and middle of the cavity. The ΔTmax ranged from 7.62 to 16.74 °C at 0.625 mm apical from the top, 4.83 to 11.39 °C at the floor of the cavity, and 3.16 to 8.09 °C in the dentin 1 mm beneath the cavity base. The ΔTmax of composite and dentin increased and the time to reach ΔT = 5 °C decreased with increasing duty ratio at constant radiant exposure. In the Increase mode, ΔTmax was lower than that of 50%/20 s mode. The ΔTmax in the Decrease mode was similar to that of 100%/10 s mode. Significance: The PWM-LED curing light system controlled by a microcontroller provided a useful tool of varying the radiant emittance and cure time with constant radiant exposure to evaluate temperature change of composite and dentin. These result will be helpful to determine proper curing modes with varying radiant emittance of the LED curing light for decreasing temperature change of composite and dentin. At constant radiant exposure and cure times, the Increase mode showed lower and slower temperature rises than the 50%/20 s and Decrease mode. Within the limitations of this in vitro study, when radiant exposure is constant, a curing light with lower radiant emittance can induce relatively low thermal transfer, thereby decreasing the risk of pulpal damage.

KW - Composite

KW - Infrared thermal camera

KW - LED curing light

KW - Pulse width modulation (PWM)

KW - Temperature change

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