Objectives: To evaluate the distribution of different light curing units (LCUs) in swiss dental practices and to investigate the properties of the different curing units.
Methods: Ten percent of LCUs in dental practices of different regions in Switzerland were randomly evaluated (220 LCUs). With a questionnary the service age, the mode of constancy-test and the dentist's satisfaction was evaluated. All LCUs were standardised tested for light intensity (Ulbricht sphere), spectral emission, light scattering, heat generation and defects. Differences were evaluated with descriptive statistics.
Results:
Table: Variations of different parameters of LCUs (only LCUs mentioned, where n>10)
|
| Light intensity (mW/cm2)
| Spectral emission peak (nm)
| Light scattering at tip end (°)
| |||
|
| Minimum
| Maximum
| from
| to
| Minimum
| Maximum
|
Astralis10
| 656.5
| 1655
| 378.29
| 535.81
| 49.6
| 88.9
|
Bluephase
| 537.5
| 1316.5
| 392.57
| 536.16
| 44.19
| 83.96
|
EliparFreelight2
| 230.5
| 1064.5
| 415.82
| 529.8
| 62.77
| 75.25
|
LEDemetron
| 397
| 1282
| 415.11
| 531
| 50.63
| 76.47
|
Smartlight
| 827.5
| 1653
| 417
| 536
| 87.15
| 123.49
|
LED LCUs were widely distributed (>65%) except one region where the distribution was in favor of halogen LCUs. The service age was between 0-5 years (39 LCUs 6-10 years, 11 LCUs 11-15 years). There was a low frequency of constancy tests (15 out of 124 practices) and overall satisfaction of dentists was good. The variability in LCUs properties was very large (Table). The light intensity of 6.4% LCUs was <400mW/cm2 (33.7%<800mW/cm2). Heat generation was correlated to light intensity (Pearson-correlation coefficient = 0.68). Forty-two LCUs were contaminated with bonding remnants or other substances, 67 had damages and 33 LCUs were damaged and contaminated.
Conclusion: Even manufacturers set quality standards of LCUs, there is a large variability in properties when LCUs are used in daily practice. The total amount of insufficient and damaged LCUs seemes too high. Constancy tests and proper handling have to be improved in daily practices.