Effect of thermal cycling on temperature changes and bond strength in different test specimens

Figures & data

Table 1. Materials used in the investigation.

Product	Manufacturer	Lot no.	Expiry date
Filtek™ Supreme XTE Universal Restorative A2B	3MEspe Dental Products, St. Paul, MN 55144-1000	N941996 N904514	2020-08 2020-11
Scotchbond Universal Adhesive	3MEspe Dental Products, St. Paul, MN 55144-1000	70831A	2019-07
Permadyne™Garant 2:1 Light bodied Consistency Polyether Impression Material	3MEspe Dental Products St. Paul, MN 55144-1000	3804066	2019-07

Figure 1. Various sized composite blocks, test specimens named a, b, c, and d with thermocouples placed in the centre or half-way from surface to centre.

Figure 2. Test specimen assemblies named e, f, and g, with thermocouples placed in the centre radius between tooth and composite.

Figure 3. Overview of composite block cut in the x and y directions, with rod ends color-coded for identification of position and used for micro-tensile testing.

Table 2. Temperature measured in resin based composite test specimens in 5 °C water bath at different dwell times (n = 25).

	Specimen designation
Specimen size	a 5 x 10 x 10 mm	b 10 x 10 x 10 mm	c 15 x 10 x 10 mm	d 15 x 10 x 10 mm
Thermocouple	Centre	Centre	Centre	2.5 mm from surface
Dwell time (s)
20	7.8 ± 0.11 °C	14.3 ± 0.25 °C	17.7 ± 0.22 °C	12.3 ± 0.65 °C
30	5.6 ± 0.06 °C	9.2 ± 0.09 °C	12.1 ± 0.13 °C	8.7 ± 0.19 °C
40	5.2 ± 0.11 °C	6.3 ± 0.15 °C	8.0 ± 0.18 °C	6.6 ± 0.16 °C
50	5.0 ± 0.05 °C	5.7 ± 0.16 °C	6.8 ± 0.11 °C	6.1 ± 0.13 °C
60	5.0 ± 0.06 °C	5.3 ± 0.15 °C	5.7 ± 0.07 °C	5.4 ± 0.16 °C

Table 3. Temperature measured in resin based composite test specimens in 55 °C water bath at different dwell times (n = 25).

	Specimen designation
Specimen size	a 5 x 10 x 10 mm	b 10 x 10 x 10 mm	c 15 x 10 x 10 mm	d 15 x 10 x 10 mm
Thermocouple	Centre	Centre	Centre	2.5 mm from surface
Dwell time (s)
20	52.2 ± 0.14 °C	45.2 ± 0.37 °C	42.4 ± 0.44 °C	48.0 ± 1.01 °C
30	54.3 ± 0.08 °C	50.4 ± 0.20 °C	48.0 ± 0.14 °C	51.4 ± 0.10 °C
40	55.2 ± 0.02 °C	53.0 ± 0.63 °C	51.1 ± 0.23 °C	53.4 ± 0.14 °C
50	55.2 ± 0.11 °C	54.4 ± 0.17 °C	53.1 ± 0.32 °C	55.2 ± 0.14 °C
60	55.2 ± 0.14 °C	55.0 ± 0.07 °C	54.2 ± 0.10 °C	55.1 ± 0.17 °C

Table 4. Temperature measured in the centre of specimens at the adhesive layer in 5 °C water bath at different dwell times (n = 25).

	Specimen designation
	e	f	g
Specimen size	10 mm Ø×10 mm composite cylinder on tooth	10 mm Ø×10 mm composite cylinder on tooth, mounted in resin	2.38 mm Ø×4 mm composite cylinder on tooth, mounted in resin
Dwell time (s)
20	17.6 ± 0.35 °C	22.4 ± 1.40 °C	7.6 ± 0.13 °C
30	13.0 ± 0.15 °C	18.5 ± 0.19 °C	7.0 ± 0.08 °C
40	8.7 ± 0.31 °C	16.0 ± 0.56 °C	6.2 ± 0.15 °C
50	7.4 ± 0.27 °C	14.3 ± 0.25 °C	6.1 ± 0.19 °C
60	6.3 ± 0.09 °C	12.9 ± 0.17 °C	6.0 ± 0.14 °C

Table 5. Temperature measured in the centre of specimens at the adhesive layer in 55 °C water bath at different dwell times (n = 25).

	Specimen designation
	e	f	g
Specimen size	10 mm Ø×10 mm composite cylinder on tooth	10 mm Ø×10 mm composite cylinder on tooth, mounted in resin	2.38 mm Ø×4 mm composite cylinder on tooth, mounted in resin
Dwell time (s)
20	42.2 ± 0.45 °C	37.8 ± 1.00 °C	53.2 ± 0.15 °C
30	46.9 ± 0.20 °C	41.6 ± 0.17 °C	53.9 ± 0.14 °C
40	50.2 ± 0.16 °C	43.7 ± 0.66 °C	54.2 ± 0.28 °C
50	52.4 ± 0.30 °C	45.8 ± 0.19 °C	54.4 ± 0.20 °C
60	53.8 ± 0.22 °C	46.9 ± 0.12 °C	54.7 ± 0.15 °C

Table 6. Repair micro-tensile bond strength of test specimens stored in water for 3 months and tested after thermal cycling and without thermal cycling.

3 months in water + thermal cycling (n = 24 in each group)		3 months in water (control) (n = 8 in each group)
outer specimens	inner specimens	outer specimens	inner specimens
37.8 ± 8.8 MPa^A,B,C	55.5 ± 8.5 MPa^A	58.3 ± 4.2 MPa^B	59.1 ± 6.4 MPa^C

Groups with same upper-case letters are statistically significant different (p < .05).