|Year : 2023 | Volume
| Issue : 1 | Page : 8-10
Assessment of the functional efficacy of various light-curing units of different manufacturers
Nikhel Dev Wazir1, Deebah Choudhary2, Hemanee Rathore3
1 Professor and HOD, Department of Conservative Dentistry and Endodontics, Institute of Dental Sciences, Jammu, Jammu and Kashmir, India
2 Assistant Professor, Department of Conservative Dentistry and Endodontics, Institute of Dental Sciences, Jammu, Jammu and Kashmir, India
3 Consultant, Private Practitioner, Jammu and Kashmir, India
|Date of Submission||11-May-2020|
|Date of Acceptance||31-May-2020|
|Date of Web Publication||31-Mar-2023|
Dr. Nikhel Dev Wazir
Department of Conservative Dentistry and Endodontics, Institute of Dental Sciences, Sehora, Jammu, Jammu and Kashmir
Source of Support: None, Conflict of Interest: None
Background: Light plays an important role in polymerizing a light-cured resin-based composite as a hard restorative material. The present study was conducted to assess the functional efficacy of various light-curing units (LCUs) available to us.
Materials and Methods: The present study was conducted in the Department of Endodontics on 60 different LCUs of different manufacturers. Parameters such as type of light-curing unit, the curing protocol, and frequency of bulb replacement were also recorded.
Results: Out of 60 LCUs, 26 were quartz–tungsten–halogen (QTH) and 34 were light-emitting diodes (LEDs). The mean intensity of QTH was 486.3 W/cm2 and of LED was 612.1 W/cm2. The difference was significant (P < 0.05). Nineteen QTH and 22 LEDs were satisfactory, while 7 QTH and 12 LEDs were unsatisfactory. The difference was nonsignificant (P > 0.05).
Conclusion: The authors found that maximum satisfactory results were seen with QTH type as compared to LED type.
Keywords: Composite, light curing, polymerizing
|How to cite this article:|
Wazir ND, Choudhary D, Rathore H. Assessment of the functional efficacy of various light-curing units of different manufacturers. Int J Prev Clin Dent Res 2023;10:8-10
|How to cite this URL:|
Wazir ND, Choudhary D, Rathore H. Assessment of the functional efficacy of various light-curing units of different manufacturers. Int J Prev Clin Dent Res [serial online] 2023 [cited 2023 Jun 10];10:8-10. Available from: https://www.ijpcdr.org/text.asp?2023/10/1/8/373357
| Introduction|| |
Light-activated composite became available in market in the early 1970s. This was regarded as advancement in the field of conservative dentistry. Tooth-colored restorations were popular in those days. Direct or indirect light-cured tooth-colored resins are widely used since then and are showing superior results. Light plays an important role in polymerizing a light-cured resin-based composite as a hard restorative material. There are different specifications that vary according to the manufacturer. Correct wavelength of light-curing unit (LCU) allows better polymerization of composite materials.
Many variables manipulate the quality of the energy delivered to composite restorations such as the intensity light yield, the spectral outflow from the LCU, and the wavelength. A wavelength of adequate specification is necessary to ensure photoinitiators to be activated inside the resin. The term of light delivery from the LCU to the resin, shade of the composite, separation between the curing tip and the resin surface, and thickness of the composite increment are other parameters that play an important role. Intensity of the light is most essential among all.
In market, different LCUs are available. Quartz–tungsten–halogen (QTH), light-emitting diode (LED), plasma arc curing (PAC), and argon laser units are commonly available LCUs. Clinically, the most mainstream types of LCUs utilized as a part of dental practice are QTH and LED units. The newer era of LED units is conquering the disadvantages of QTH units. The rate of clinically acceptable LCUs found in various dental practices has differed, from as low as 10% to as high as 70%. Considering this, the present study was conducted to assess the functional efficacy of various LCUs available to us.
| Materials and Methods|| |
The present study was conducted in the Department of Conservative Dentistry and Endodontics, Institute of Dental Sciences Sehora, Jammu. It comprised 60 different LCUs of different manufacturers. Ethical clearance was obtained from the institutional ethical committee.
The curing tip of each LCU was centered perpendicular to the sensor of radiometer, and the LCU was then activated for a 20-s curing cycle. To avoid errors, three different readings were recorded and an average was obtained and it was considered the final light intensity produced by that particular unit. Parameters such as type of light-curing unit, the curing protocol, and frequency of bulb replacement were also recorded. The amount of energy density × duration of exposure in seconds needed to cure resin varies in value, from 6 to 36 J/cm2, and a value of 12 J/cm2 was set as a minimum energy level for acceptable curing of a 2-mm resin increment. To achieve the minimum energy level necessary for these tested LCUs to be considered clinically acceptable, and depending on the curing time protocol, the QTH unit needed to deliver a minimum irradiance value of 300 mW/cm2. The results thus obtained were subjected to statistical analysis. P < 0.05 was considered statistically significant (P < 0.05).
| Results|| |
[Table 1] shows that out of 60 LCUs, 26 were QTH and 34 were LEDs.
[Table 2] shows that the mean intensity of QTH was 486.3 W/cm2 and of LED was 612.1 W/cm2. The difference was statistically significant (P < 0.05).
[Table 3] shows that 19 QTH and 22 LEDs were satisfactory, while 7 QTH and 12 LEDs were unsatisfactory. The difference was nonsignificant (P > 0.05).
| Discussion|| |
LCUs are handheld devices that are used for the polymerization of visible light-activated dental materials. The four types of LCUs such as QTH, LED, PAC, and argon laser units are extensively used worldwide. Factors such as wavelength and intensity of the output of LCUs, distance between cavity and tip of LCUs, direction of tip of LCUs, location and size of prepared cavity, the wavelength and bandwidth of the curing light, the curing light intensity, the irradiation time, and color and thickness of the composite determine success of any light-cured restorative materials. Composite resins are commonly used restorative materials. In this, camphorquinone is the light-sensitive component, which responds to irradiation by creating free radicals and initiates the polymerization process. The present study was conducted to assess the functional efficacy of various LCUs available to us.
In this study, we included 60 LCUs, of which 26 were QTH and 34 were LEDs. The mean intensity of QTH was 486.3 W/cm2 and of LED was 612.1 W/cm2. Sahu et al. evaluated the output intensity of 110 LCUs with the help of Bluephase® radiometer. The average output intensity was divided into two categories for QTH (300 mW/cm2) and for LED (600 mW/cm2). Among the QTH light-curing units, 32 out of 41 (78%) were found out to be satisfactory, while 44 LED light-curing units out of 69 (63.7%) were satisfactory based on the criteria used for the study.
We found that 19 QTH and 22 LEDs were satisfactory, while 7 QTH and 12 LEDs were unsatisfactory. Irradiance is the number of photons delivered to the sample per unit of time, regardless of the area illuminated. Failure to achieve appropriate irradiance leads to the inadequate polymerization, bringing in a low monomer polymer transformation rate, which results into inferior physical properties, more water absorption, microleakage, postoperative sensitivity, and staining of the resin composite. Accordingly, both the degrees of cure on the surface closest to the light source and depth of cure have been appeared to be affected by the intensity of the LCUs.
There are certain challenges among dentists as composite surface hardness is not a consistent guide because even at a low light intensity, the surface can adequately harden whereas the depth of the cure is not adequate. If the device is not routinely used, the output light of the device decreases, but this is not noticeable by the unarmed eye because sometimes a seemingly bright light is not suitable for wavelengths. Hence, a digital radiometer is required to determine the intensity of the curing light of the units to evaluate when the device needs to repaired or replaced.
Omidi et al. conducted a study in which a total of 95 LCUs were examined, of which 61 (64.2%) were of LED type and 34 (35.8%) were of QTH type. While average light intensity in LED units was significantly higher than in QTH devices, the two device types were not significantly different regarding desirable light intensity (i.e., ≥300 mw/cm2). A negative correlation was observed between clinical age and light intensity. In addition, bulb replacement in QTH devices was over three times as much as in LED units. Furthermore, repairing QTHs was more than twice as much frequent as fixing LEDs. The most common reason for repair was the breakage of the tip of the device.
| Conclusion|| |
The authors found that maximum satisfactory results were seen with QTH type as compared to LED type.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3]