Clinical Research Associates

Resin Curing Light Test Results
Which curing lights and resins cause the least detrimental effects?

This section on this internet site is designed to be used in conjunction with the December 1998 CRA Newsletter (Vol. 22, Issue 12). This information does not replace any information contained in the original publication, but is designed to provide background test methods and results leading to the conclusions reached in the original publication.

Contents:	Resin Shrinkage - How much does resin shrink when cured?
	Stress at Gingival Margin - How much stress on a tooth prep is created from resin shrinkage?
	Resin "Brittleness" (Flexural Modulus) - How brittle or stiff is a material?
	Methods & Procedures - How were resin curing lights tested?

The following two graphs show the average percent shrinkage for each combination of curing light, resin, and color.
The "CONTROL" light was an Optilux 401 regulated to produce 400 mW/cm2 output.

Shrinkage - Standard Cure Time

Shrinkage - Minimum Cure Time

Summary of Graphs: Shrinkage ranged from 1.8 to 3.4 percent. The curing light used did not have a significant effect on resulting shrinkage of the resin. Heliomolar had lowest shrinkage values, while Spectrum TPH had the highest. For comparison, Bisfil II autocure control resin had 2.7 percent shrinkage.

% Shrinkage Using Watt's Method

Using Standard Cure Times

Watts Shrinkage by Curing Light Watt's Shrinkage by Resin Brand

Stress at Gingival Margin

To Test Methods & Procedures

The following table gives the average stress values for each combination of light, resin, & color tested. Also given is the standard deviation (StdDev), number of samples (N), & minimum cure time used (CT).

The CONTROL light was an Optilux 401 regulated to produce 400 mW/cm2 output. The EXPERIMENTAL light consisted of 200 mW/cm2 for 3 sec, a 3 min pause, then 600 mW/cm2 for 30 sec.

RESIN & COLOR
LIGHT	Heliomolar, A1	Herculite, A1	Silux Plus, light	Spectrum TPH, A2	Z100, A3	Bisfil II, universal
BriteSmile	Ave = 9.1	Ave = 9.8	Ave = 8.7	Ave = 11.4	Ave = 24.5
	StdDev = 1.8	StdDev = 1.7	StdDev = 1.6	StdDev = 0.0	StdDev = 4.0
	N = 4	N = 3	N = 3	N = 2	N = 3
	CT = 4 sec	CT = 2 sec	CT = 3 sec	CT = 2 sec	CT = 2 sec
Elipar Hightlight	Ave = 13.5	Ave = 11.4	Ave = 21.6	Ave = 11.1	Ave = 17.9
	StdDev = 2.1	StdDev = 2.4	StdDev = 1.0	StdDev = 3.5	StdDev = 5.2
	N = 4	N = 3	N = 3	N = 4	N = 3
	CT = 25 sec	CT = 15 sec	CT = 20 sec	CT = 15 sec	CT = 10 sec
PAC Light	Ave = 15.2	Ave = 10.6	Ave = 19.8	Ave = 16.6	Ave = 23.1
	StdDev = 3.9	StdDev = 5.2	StdDev = 2.4	StdDev = 2.9	StdDev = 4.9
	N = 4	N = 3	N = 2	N = 4	N = 2
	CT = 3 sec	CT = 2 sec	CT = 4 sec	CT = 3 sec	CT = 2 sec
Control	Ave = 14.4	Ave = 15.1	Ave = 16.8	Ave = 14.4	Ave = 28.4
	StdDev = 6.0	StdDev = 1.7	StdDev = 5.3	StdDev = 3.9	StdDev = 6.8
	N = 3	N = 2	N = 4	N = 24	N = 4
	CT = 20 sec	CT = 5 sec	CT = 15 sec	CT = 10 sec	CT = 10 sec
Experimental	Ave = 13.4	Ave = 10.7	Ave = 14.6	Ave = 16.7	Ave = 27.4
	StdDev = 2.3	StdDev = 4.1	StdDev = 3.5	StdDev = 2.0	StdDev = 0.0
	N = 3	N = 4	N = 3	N = 3	N = 1
	CT = 3 + 30 sec	CT = 3 + 30 sec	CT = 3 + 30 sec	CT = 3 + 30 sec	CT = 3 + 30 sec
None						Ave = 12.2
						StdDev = 3.2
						N = 4
						CT = autocure

Summary of Table: Stress levels ranged from 8.7 to 28.4 MPa. The curing light used to cure the resin did not significantly affect marginal stress levels. Z100 resin produced most stress. For comparison, the autocure control resin Bisfil II produced 12.2 MPa of stress.

Stress at Margin

Resin "Brittleness"
(Modulus of Elasticity)

To Test Methods & Procedures

The modulus of a material (known as Modulus of Elasticity, Young's Modulus, or Flexural Modulus) is related to its stiffness. The term "brittleness" (although technically incorrect) is sometimes used in reference to modulus since stiff materials tend to fracture rather than deform when under stress.

The following tables give average modulus values for each combination of curing light, resin, and color.
The "CONTROL" and "LOW CONTROL" curing lights were an Optilux 401 regulated (using a voltage regulator) to produce 400 & 200 mW/cm2 output.
For comparison: Bisfil II autocure resin had a modulus of 16,099 MPa. (NT = not tested).

Standard Cure Times (10 sec. for laser & plasma arc, 40 sec. for halogen)
Higher values represent increased "brittleness." Values are in units of megapascals (MPa).

	Heliomolar			Herculite			Silux Plus			TPH			Z100
LIGHT	A1	A3	A4	A1	A3	YB	L	UO	DDYO	A2	A3	D3	A3
Elipar Highlight (standard mode)	4949	4303	4798	11057	11725	10150	6239	6224	5357	11061	9244	10502	17469
Elipar Hightlight (2-step mode)	4300	4551	4124	10090	9851	9555	6192	5670	5767	9990	7635	10489	15867
CONTROL	4006	4177	3637	9974	9886	8910	6179	5280	5368	10721	10314	9621	14662
LOW CONTROL	3771	3605	3029	8794	7509	7327	5475	6487	4004	9461	9765	8802	13472
AccuCure 3000	3457	3755	2581	9124	8571	6845	4207	4966	3705	8967	8759	10003	13171
BriteSmile	4133	3800	3179	9964	9250	8119	5998	4943	3963	8601	10254	8757	12669
Optilux 500	4240	4539	4009	10786	10240	11886	6274	5557	4737	9517	9779	9733	14395
PAC Light	4332	4014	3673	10899	10089	8956	5620	5328	4747	9617	9174	9578	13953

Minimum Cure Times (Minimum Time to Develop 90% Hardness) See minimum cure time methods

	Heliomolar			Herculite			Silux Plus			TPH			Z100
LIGHT	A1	A3	A4	A1	A3	YB	L	UO	DDYO	A2	A3	D3	A3
Elipar Highlight (standard mode)	4440	3571	4524	9001	7729	7826	5232	5109	4781	10175	9718	9818	12381
Elipar Hightlight (2-step mode)	4405	4972	4455	9117	9583	NT	5598	5274	4848	9137	8819	8875	10396
CONTROL	3692	4670	3637	5992	9682	7413	5682	5327	NT	8190	8902	7584	11755
LOW CONTROL	3771	3605	3366	5986	7891	7721	5341	4686	4525	7544	8228	7469	11078
AccuCure 3000	3119	3203	2120	7512	8571	6845	3950	3466	2833	8021	8434	5349	8725
BriteSmile	2722	2812	2634	4998	6304	5728	4657	4856	3222	5481	4825	6665	6901
Optilux 500	4857	5731	4459	7411	9570	8513	4865	5232	4470	7620	5982	7815	9570
PAC Light	3446	3588	2882	6069	9711	7741	5982	4786	4119	7957	8903	6874	10350

Summary of Tables: Modulus values ranged from 2,120 to 17,469 MPa. All curing lights produced similar modulus values for each resin and color. Heliomolar consistently had the lowest modulus, while Z100 & Bisfil II had the highest. Use of the minimum cure time verses the standard cure time resulted in slightly lower values. There was a trend for lighter colors to have a slightly higher modulus.