Correlation of Composite Thickness and Tip Distance With Composite Cure
Objectives: To study tip distance and composite increment thickness effects on monomer conversion (MC) in a simulated Class I preparation. Methods: Printed opaque plastic matrices (composite thickness, 5-mm dia holes) and printed opaque shafts (tip distance, 5 mm dia) simulated incremental filling of a Class I preparation: first incremental layer thickness (1, 2, or 3mm), tip distances (7, 6, 5mm) respectively; second incremental layer thickness (1, 2, or 3mm), tip distances (5, 4, and 3mm); third incremental layer thickness (1 or 2mm), tip distances (3 or 2mm). An empty matrix was placed on a horizontal attenuated total reflectance unit, filled with composite (Premise A2, Kerr), and the appropriate shaft placed over top. Infrared (IR) spectra (16 scans, 2 cm-1 resolution) were obtained pre-exposure and 3 min subsequent to a 5-s exposure (Demi Ultra, Kerr), after which, the IR spectrum of the top, irradiated surface was obtained separately. MC was determined by comparing changes peak absorption height ratios of aliphatic and aromatic C=C between cured and uncured states. Five replications were obtained in a randomized order. MC values were compared using a 2-way, repeated measures ANOVA and Tukey post-hoc tests at a pre-set alpha of 0.05. Results: Table presents results. Within a composite thickness and tip distance, top surface MC was significantly greater than at the corresponding bottom surface (P<0.001). Top surface MC values for the 1st increment were significantly less than the 3rd increment (closest to light tip). Significant interactions were seen between tip distance and composite thickness among bottom surface MC values, with the MC of 5-mm distance, 3-mm thick, 1st increment being significantly lower than all other bottom surfaces. Conclusions: When incrementally restoring a deep Class I restoration, using manufacturer-recommended exposure times, composite conversion is significantly affected by increment thickness and distance to the light curing tip.
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:3238 Abstract Category|Abstract Category(s):Dental Materials 2:Polymer-based Materials
Authors
Daniel, Cornelius
( Dental College of Georgia at Augusta University
, Augusta
, Georgia
, United States
)
Sword, Rhoda
( Dental College of Georgia at Augusta University
, Augusta
, Georgia
, United States
)
Bachand, William
( Dental College of Georgia at Augusta University
, Augusta
, Georgia
, United States
)
Mettenburg, Donald
( Dental College of Georgia at Augusta University
, Augusta
, Georgia
, United States
)
Rueggeberg, Frederick
( Dental College of Georgia at Augusta University
, Augusta
, Georgia
, United States
)
Support Funding Agency/Grant Number: Travel supported by Thomas P. Hinman/DCG Endowment Fund
Financial Interest Disclosure: NONE
Percent monomer conversion (+/- SD) with respect to composite increment thickness and distance to the curing light
% MONOMER CONVERSION
INCREMENT PROXIMITY TO TIP
INCREMENT #
THICKNESS (mm)
DISTANCE TO TO (mm)
TOP
BOTTOM
CLOSEST TO LIGHT
3
1
3
47.2 (2.5) ABC
40.6 (2.4) a
2
2
50.0 (1.0) A
38.1 (1.9) ab
2
1
5
45.3 (2.5) BCD
38.9 (1.4) a
2
4
46.7 (3.0) ABCD
33.3 (2.8) c
3
3
48.4 (2.7) AB
17.6 (1.6) e
FURTHEST FROM LIGHT
1
1
7
41.6 (1.7) D
34.3 (1.7) bc
2
6
41.9 (1.2) D
24.3 (2.7) d
3
5
43.1 (2.2) CD
13.0 (1.9) f
N=5 per test condition.
At each combination of increment # and composite thickness, conversion of top surface > that of the bottom.
Within a column, values identifies with similar letters (upper case=top surface, lower case=bottom surface) are not significantly different