ABSTRACT: 0133

Evaluation of Cytotoxicity and Degree of Conversion of Orthodontic Adhesives

N. JAGDISH, Shri Ramachandra Dentl College, Chennai, MD, India

OBJECTIVES:Evaluate cytotoxic properties of five orthodontic-adhesives with and without oxygen inhibited layer(OIL);assess degree of conversion (DC) using Fourier Transform Infrared(FTIR) spectroscopy and correlate it to cytotoxicity.

METHODS:36 standardized disks prepared for each brand (Unite,TransbondXT, Heliosit,GCFujiORTHOLC,PhaseII) were divided into intact and washed (wiped with 99% acetone removing OIL) resins. Vero cells seeded in three 12-well plates for each brand (one plate each for assessment on day 1,3, and 6) were exposed to both resins immediately after removal of OIL on day 1. Cell viability determined by tetrazolium bromide reduction assay on 1,3 and 6 days after exposure of cells to resins were statistically analysed (Annova,TukeyHSD,t test,Pearson correlation).

RESULTS: With washed resins,Unite (p<0.001) and Heliosit (p<0.01) showed increased viability on all days while TransbondXT established the same only on day1. Other washed resins demonstrated decreased viability compared to intact resins.

Viability of Vero cells (N=6 for all):

Materials tested	DAY 1(24Hrs)		DAY 3(72 Hrs)		DAY 6(144Hrs)
Materials tested	INTACT	WASHED	INTACT	WASHED	INTACT	WASHED
Unite	21.30±4.03	38.35±8.22	47.77±5.89	72.48±6.05	47.49±5.77	72.14±6.09
Transbond XT	48.02±5.93	72.85±6.12	58.23±20.12	36.27±7.90	48.64±5.95	36.13±8.03
Heliosit	61.20±10.95	80.60±8.40	37.14±8.18	63.80±15.16	38.15±3.34	47.50±7.40
GCFuji ORTHOLC	37.86±3.50	25.79±5.22	34.99±4.40	14.43±2.74	23.50±3.98	5.48±2.09
PhaseII	34.92±4.32	23.37±4.08	26.35±3.99	14.67±2.98	23.31±3.86	12.66±2.69

Percentages of DC (N=6 for all):

Materials tested	Mean,Standard deviation
Unite	51.65±0.74
TransbondXT	48.74±0.29
Heliosit	48.63±0.34
GCFujiORTHOLC	38.88±3.46
PhaseII	31.77±0.53

Pearson Correlation between DC and viability expressed by intact resins on day1:

Materials tested	Pearson correlation	Significance
Unite	-0.814	0.049
TransbondXT	-0.615	0.194
Heliosit	0.408*	0.421**
GCFujiORTHOLC	-0.381	0.456
PhaseII	0.058*	0.913**

*Positive correlation ;**Statistically insignificant (p>0.05)

CONCLUSION:All materials tested revealed toxicity. Residual monomer leaching and associated toxicity exhibited by Unite was almost complete by day 1 and it showed maximum DC. Though results donot translate to any direct toxic-effects on patients, further studies on long-term effects of adhesives needs to be investigated.

Seq #32 - Keynote Address and Cytotoxicity of Restorative Materials
9:00 AM-10:30 AM, Thursday, July 3, 2008
Metro Toronto Convention Centre Room 801A

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