The Ability of Dental Practitioners to Light-Cure Simulated Restorations

Influence of Layer Thickness and Shade on the Transmission of Light through Contemporary Resin Composites

BACKGROUND

Material-dependent parameters have an important impact on the efficiency of light polymerization. The present in vitro study aimed to investigate the influence of the increment thickness and shade of nano- and nanohybrid resin composites on the transmission of curing light.

METHODS

Three contemporary resin composites were evaluated: Tetric EvoCeram® (TEC); Venus Diamond® (VD); and Filtek Supreme XTE® (FS XTE). Light transmission (LT) was recorded in accordance with the sample thickness (0.5 to 2.7 mm) and the shade. Polymerized samples were irradiated for 10 s each using the high-power LED curing light Celalux 2 (1900 mW/cm2). LT was simultaneously recorded using the MARC Patient Simulator (MARC-PS).

RESULTS

LT was strongly influenced by the composite layer thickness. For 0.5 mm-thick samples, a mean power density of 735 mW/cm2 was recorded at the bottom side. For the 2.7 mm samples, a mean power density of 107 mW/cm2 was measured. Only LT was markedly reduced in the case of darker shades. From A1 to A4, LT decreased by 39.3% for FS XTE and 50.8% for TEC. Dentin shades of FS XTE and TEC (A2, A4) showed the lowest LT.

CONCLUSIONS

The thickness and shade of resin composite increments strongly influences the transmission of curing light. More precise information about these parameters should be included in the manufacture manual.

Longevity of composite restorations is definitely not only about materials

OBJECTIVES

This review study provides an overview of factors that influence the longevity of all types of direct resin composite restorations.

METHODS

A systematic search was performed in PubMed, Scopus, and Web of Science databases for articles reporting data from primary longitudinal clinical studies on composite longevity published 2011-2021. Prospective or retrospective studies with restorations in permanent dentition, with follow-up periods of at least 5 years were included.

RESULTS

In total, 33 articles were included with different study designs, practice settings, datasets, countries of origin, and sample sizes. Annual failure rates of restorations ranged from 0.08% to 6.3%. Survival rates varied between 23% and 97.7%, success rates varied between 43.4% and 98.7%. Secondary caries, fractures, and esthetic compromise were main reasons for failures. Risk factors for reduced restoration durability included patient-level factors (e.g., caries risk, parafunctional habits, number of check-ups per year, socioeconomic status), dentist factors (different operators, operator's experience), and tooth/restoration factors (endodontic treatment, type of tooth, number of restored surfaces). Patient gender and the composite used generally did not influence durability.

SIGNIFICANCE

A number of risk factors are involved in the longevity of composite restorations. Differences between composites play a minor role in durability, assuming that materials and techniques are properly applied by dentists. Patient factors play a major role in longevity. The decision-making process implemented by dentists relative to the diagnosis of aging or failed restorations may also affect the longevity of restorations. Clinicians should treat patients comprehensively and promote a healthy lifestyle to ensure longevity.

Depth of cure of 10 resin-based composites light-activated using a laser diode, multi-peak, and single-peak light-emitting diode curing lights

OBJECTIVES

To evaluate the depth of cure (DOC) of ten contemporary resin-based composites (RBCs), light-cured using different LCUs and exposure times.

METHODS

The power, radiant emittance, irradiance, radiant exposure (RE), and beam profiles from a laser (M, Monet), a multi-peak (V, Valo Grand), and single-peak (S, SmartLite Pro) LCU were measured. The DOC was measured using a 6-mm diameter metal mold and a solvent dissolution method to remove the uncured RBC. The length of the remaining RBC was divided by 2. The exposure times were: 1s and 3s for M, 10s and 20s for V, and 10s and 20s for S. Data were analyzed using: Bland-Altman distribution, Pearson's Correlation, and an artificial neural network (ANN) to establish the relative importance of the factors on the DOC (α=0.05; β=0.2).

RESULTS

Significant differences were found in the DOC of the different LCUs and composites. The laser LCU emitted the highest power, radiant emittance, and irradiance. However, this LCU used for 1 s delivered the lowest RE and produced the shortest DOC in all ten RBCs. The ANN demonstrated that the RE is the most critical factor for the DOC. Bland-Altman comparisons showed that the DOCs achieved with the laser LCU used for 1s were between 17 - 34 % shorter than the other conditions.

CONCLUSIONS

Although the laser LCU cured all 10 RBCs when used for 1s, it produced the shallowest DOC, and some RBCs did not achieve the minimum DOC threshold. The RE and not the irradiance was the most important factor in determining the DOC of RBCs.

CLINICAL SIGNIFICANCE

Despite delivering high power and irradiance, the laser used for l s delivered a lower radiant exposure than the conventional LCUs used for 10 s. This resulted in a shorter DOC.