We are using cookies to implement functions like login, shopping cart or language selection for this website. Furthermore we use Google Analytics to create anonymized statistical reports of the usage which creates Cookies too. You will find more information in our privacy policy.
OK, I agree I do not want Google Analytics-Cookies
Quintessence International



Forgotten password?


Quintessence Int 40 (2009), No. 3     6. Feb. 2009
Quintessence Int 40 (2009), No. 3  (06.02.2009)

Page 203-214, PubMed:19417884

Shrinkage and hardness of dental composites acquired with different curing light sources
Clifford, Stephen S. / Roman-Alicea, Karla / Tantbirojn, Daranee / Versluis, Antheunis
Objectives: Curing light sources propel the photopolymerization process. The effect of 3 curing units on polymerization shrinkage and depth of cure was investigated.
Method and Materials: The curing lights were a conventional and a soft-start quartz-tungstenhalogen (QTH) light source and a light-emitting diode (LED) source. The soft-start QTH and LED intensity outputs were 9% and 17% less than the conventional QTH source, respectively. For a 40-second light cure, the light energy was 32% and 14% lower, respectively. The light sources were applied to 4 restorative composites (microfilled, 2 hybrids, and nanofilled). For each light unit-composite combination, the development of postgel shrinkage during polymerization was measured with strain gauges (n = 15), and the Knoop hardness was tested at 0.5-mm-depth increments to assess degree of cure 15 minutes after polymerization (n = 5). The results were statistically analyzed with 2-way ANOVA at .05 significance level, followed by pairwise comparisons.
Results: Both factors, light source and composite, significantly affected postgel shrinkage and hardness (P < .05). The conventional QTH unit generally produced the highest shrinkage and hardness (at composite surface and 2-mm depth). The soft-start QTH unit generated the least shrinkage but achieved the lowest depth of cure. The resulting values for the LED unit were mostly in between the results of the other 2 units.
Conclusion: Curing lights should provide sufficient light energy to thoroughly cure composite restorations, which might be achieved without compromising shrinkage stresses if initial intensity is reduced.

Keywords: composite, cure, curing light, hardness, light energy, light intensity, shrinkage, soft start