Restor Dent Endod.  2020 Nov;45(4):e55. 10.5395/rde.2020.45.e55.

Assessment of the radiant emittance of damaged/contaminated dental lightcuring tips by spectrophotometric methods

• Balhaddad AA
• Garcia I
• Collares F
• Felix CM
• Ganesh N
• Alkabashi Q
• Massei W
• Strassler H
• Melo MA

• KMID: 2512046
• DOI: http://doi.org/10.5395/rde.2020.45.e55

Abstract

Objectives
This study investigated the effects of physically damaged and resin-contaminated tips on radiant emittance, comparing them with new undamaged, non-contaminated tips using 3 pieces of spectrophotometric laboratory equipment.
Materials and Methods
Nine tips with damage and/or resin contaminants from actual clinical situations were compared with a new tip without damage or contamination (control group). The radiant emittance was recorded using 3 spectrophotometric methods: a laboratory-grade thermopile, a laboratory-grade integrating sphere, and a portable light collector (checkMARC).
Results
A significant difference between the laboratory-grade thermopile and the laboratory-grade integrating sphere was found when the radiant emittance values of the control or damaged/contaminated tips were investigated (p < 0.05), but both methods were comparable to checkMARC (p > 0.05). Regardless of the method used to quantify the light output, the mean radiant emittance values of the damaged/contaminated tips were significantly lower than those of the control (p < 0.05). The beam profile of the damaged/ contaminated tips was less homogeneous than that of the control.
Conclusions
Damaged/contaminated tips can reduce the radiant emittance output and the homogeneity of the beam, which may affect the energy delivered to composite restorations. The checkMARC spectrophotometer device can be used in dental offices, as it provided values close to those produced by a laboratory-grade integrated sphere spectrophotometer. Dentists should assess the radiant emittance of their light-curing units to ensure optimal curing in photoactivated, resin-based materials.

Keyword

Dental; Dental materials; Light curing; Operative; Polymerization; Resin composite

Figure

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  Figure 1 Contaminated and damaged light tips. (A) Light tip contaminated with resin composite and debris. (B) Damaged light tip by scratches, dents, and chipping.

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  Figure 2 The radiant emittance values were recorded via spectrophotometric methods. (A) A laboratory-grade thermopile system. (B) A laboratory-grade integrating sphere spectrophotometer. (C) An in-office checkMARC portable spectrophotometer.

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  Figure 3 Radiant emittance levels of the control tip. (A) An appearance of the control tip and the measured active tip diameter. (B) Representative image of the light beam radiant emittance profile for the control tip. The color bar on the right shows the visual representation of radiant emittance expressed in mW per cm2 corresponding to the colors seen. The profile presents an abundance of the green color representative of the range of 600–700 mW/cm2 with scattered dots in a hot color (yellow-orange) representing radiance with emission in the range of 800–900 mW/cm2. The profile beam image also shows peripheral areas in blue and gray colors, representative of radiance at 400 and below 400 mW/cm2, respectively. (C) Radiant emittance assessment of non-damaged and non-contaminated tips by the 3 spectrophotometric methods. No significant difference was found between the checkMARC spectrophotometer and the other methods (p < 0.05). Values with different letters are significantly different (p < 0.05).

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  Figure 4 Radiant emittance levels of the damaged/contaminated tips. (A) Representative images of the beam profile of damaged/contaminated light tips. The colors in the beam profile represent the amount of radiant emittance captured at each area across the light-curing unit tip. The higher the normalized radiant emittance value, the better the performance of the light-curing unit (high-value areas: light green). The color bar on the right shows the visual representation of radiant emittance expressed in mW per cm2 corresponding to the colors seen. The profile beam images for damaged/contaminated tips show an increased abundance of peripheral and central areas in blue and gray colors representative of radiance at 400 and below 400 mW/cm2, respectively. In B, the radiant emittance assessments of damaged/contaminated tips (n = 9) by the 3 spectrophotometric methods are shown. The radiant emittance assessed by the thermopile was significantly (p < 0.05) lower than the values for the laboratory-grade sphere. No significant differences were found between the checkMARC spectrophotometer and the other methods (p < 0.05). Values with different letters are significantly different (p < 0.05).

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  Figure 5 Impact of damage/contamination on radiant emittance. (A) Representative illustration of a clinical restorative scenario where a mesio-distal occlusal composite restoration is placed and cured by a damaged tip. The overlapping image of the non-uniform beam profile over the composite restoration should be noted. The lack of homogeneity in the produced radiant emittance profile could compromise the optimal polymerization of the restoration. The black arrows indicate areas that may not receive the radiant emittance appropriately. (B) Radiant emittance results and percentage reduction of radiance relative to the control. On the first y-axis, the bar plot shows radiant emittance results expressed in mW/cm2. Each method was used to capture the radiant emittance values from damaged/contaminated tips and compared to those with no damage or contamination (control). The difference in the power output between the damaged/contaminated and control tips was significant when the thermopile and the laboratory-grade sphere spectrophotometer were used. Damaged/contaminated tips significantly demonstrated lower radiant emittance values than the control (p < 0.05). In this plot, values with different letters are significantly different (p < 0.05).

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