IADR Abstract Archives

Impact of Beam Profile on Resin-Composite Conversion and Micro-flexural Strength

Objectives: The objective of this study was to evaluate the effect of curing-light beam profile of multiple light curing units (LCUs) on the degree of conversion (DC) and micro-flexural strength (μ-flexural strength) of a RMC.
Methods: Forty-five nano-filled hybrid RMC (Tetric EvoCeram, Ivoclar Vivadent, Amherst, NY) specimens were fabricated. Quartz-tungsten-halogen (QTH) (Optilux 401) (O), polywave (VALO Cordless) (V) and monowave (Demi Ultra) (DU) light-emitting-diode (LED) LCUs were investigated at different light-curing locations (LCLs): (1) the center of the LCU; (2) 1.5 mm to the left of the center of the LCU; and (3) 1.5 mm to the right of the center of the LCU. Specimens were stored wet in deionized water at 37^oC for 24 hours. The DC was measured on top and bottom surfaces using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Micro-flexural strength testing was performed using a universal mechanical testing machine at crosshead speed of 1 mm/min. Multi-factorial ANOVAs were used to analyze the data (α=0.05).
Results: All LCUs exhibited significant differences in DC between top and bottom surfaces at the different LCLs (Table I). Micro-flexural strength varied with LCL for DU (Table II).
Conclusions: The inhomogeneous curing-light beam profile could have a significant effect on μ-flexural strength and DC on top and bottom surfaces of RMC specimens cured at different LCLs using multiple LCUs.

Division: IADR/AADR/CADR General Session
Meeting: 2017 IADR/AADR/CADR General Session (San Francisco, California)
Location: San Francisco, California
Year: 2017
Final Presentation ID: 3221
Abstract Category|Abstract Category(s): Dental Materials 2:Polymer-based Materials

Authors

Eshmawi, Yousef ( Indiana University School of Dentistry , Indianapolis , Indiana , United States )

Al-zain, Afnan ( IUPUI , Indianapolis , Indiana , United States )

Eckert, George ( Indiana University School of Medicine , Indianapolis , Indiana , United States )

Platt, Jeffrey ( Indiana University , Indianapolis , Indiana , United States )

Financial Interest Disclosure: NONE

SESSION INFORMATION

Poster Session
Dental Materials-Polymer-based Materials VII
Saturday, 03/25/2017 , 11:00AM - 12:15PM

TABLES

TABLE I. %Degree of conversion mean (SE) for the LCUs at different locations.

		Light Curing Location
LCU	Surface	1	2	3
DU	Top	54.3 (3.0)^bBβ	65.8 (2.0)^aAα	62.3 (1.1)^aAα
DU	Bottom	60.7 (2.7)^aAα	57.5 (1.9)^bAα	58.5 (2.2)^aAα
QTH	Top	61.5 (0.8)^aAα	57.6 (0.4)^aAβ	57.8 (2.3)^aAα
QTH	Bottom	55.2 (1.2)^bAβ	52.9 (1.9)^bAβ	52.3 (2.6)^bAβ
V	Top	52.0 (0.6)^aBβ	63.0 (1.3)^aAα	60.6 (1.8)^aAα
V	Bottom	52.4 (2.4)^aAβ	50.5 (2.4)^bAβ	49.7 (1.5)^bAβ

Superscript letters represent statistical groups: lowercase between top and bottom surfaces for each LCU; uppercase letters in the same row; Greek letters between LCUs for each surface.
TABLE II. μ-flexural strength (MPa) mean (SE) for the LCUs at different locations.

	Light Curing Location
LCU	1	2	3
DU	313 (31)^bB	400 (13)^aA	369 (10)^bAB
QTH	401 (12)^aA	425 (16)^aA	405 (2)^aA
V	417 (13)^aA	418 (5)^aA	458 (21)^aA

Superscript letters represent statistical groups: lowercase in the same column; uppercase in the same row.