The Effect of Interincisal Opening, Cavity Location and Operator Experience on the Energy Delivered by a Light-Curing Unit to a Simulated Dental Restoration

Abstract

Background Curing of resin-based composites depends on the delivery of adequate total energy, which may be operator dependent. Aim To determine the effect of interincisal opening, cavity location and operator experience on the total energy delivered to simulated cavity preparation sites. Design Three cohorts were included: junior dental nurses, senior dental nurses and qualified dentists (N=5, each cohort). Each operator (participant) followed the same procedure and light-cured two simulated restorations in a MARC® patient simulator using a Demi™ light-curing unit for 20 seconds in each of the following situations: left upper second molar (UL7), interincisal opening at both 25mm and 45mm; upper central incisor (UR1), interincisal opening at 45mm. The light energy delivered by each operator in each situation was recorded. Five readings for each operator were taken at each interincisal distance. Statistical comparisons of delivered energy (J/cm2) between interincisal openings, location and groups in the total energy delivered were performed using the Kruskal-Wallis nonparametric test: α=0.05. Results Less total energy was delivered to the posterior cavity at 25mm (12.0 ± 5.3J/cm2) than at 45mm (16.9 ± 5.6J/cm2) by all operators ( P<0.05). At 45mm, less total energy was delivered to the posterior cavity compared to the anterior cavity (25.1 ± 7.4J/cm2; P<0.05). There was no statistically significant difference between junior nurses and qualified dentists ( P>0.05) but there was a significant difference in the total energy delivered between senior nurses (20.1 ± 7.8J/cm2) and junior nurses (17.5 ± 7.6J/cm2) and between senior nurses and qualified dentists (16.6 ± 8.7J/cm2) ( P<0.05). Conclusions Interincisal mouth opening, location of the cavity and operator experience affected the total energy delivered to cavities in a simulated clinical environment.

Effect of Training Method on Dental Students’ Light‐Curing Performance

“…Similar differences have been found between fourth‐year students and private practitioners 15 . It could be expected that more years of dental training would result in higher light‐curing efficiency, since Harun et al found that five years of clinical training had a positive effect on light‐curing efficacy 16 …”

“…The detector collects information from the radiant exposure delivered. The interincisal opening of the simulator was previously set to 40 mm 16 . Before use, the MARC‐PS system was calibrated 17 .…”

“…The light‐curing technique itself has a significant impact on the radiant exposure and thus on the DC of dental composites 7 . Distance and tilt angle of the light‐curing unit are factors that may significantly decrease the amount of light reaching the restorative material, 14 and these factors are particularly critical in posterior teeth due to limited access 15 , 16 . A patient simulator with cavity preparations and light sensors in both anterior and posterior teeth has been used specifically for light‐curing training for dental personnel 1 , 15 .…”

Comparison of depth of cure in opaque sealant cured with high irradiance light‐emitting diodes at various light tip distances

“…Among other inherent challenges of placing a well‐retained sealant, inadequate curing of the material in the deepest portions of the fissure is a potential reason for sealant failure 4 . This inadequate curing can be due to material factors, curing light factors, clinical techniques, or patient factors 5,6 …”

“…Contrary to clinical techniques over which practitioners have good control, patient factors such as isolation of working field and patient cooperation are additional challenges for placing a well‐retained sealant. Clinicians must also account for structural access such as intra‐incisal opening and tooth anatomy that can restrict ideal light placement 4,6 . Previous studies indicate that sealant depth of cure was affected when the light tip could not be positioned close to the material 4,11 …”