Evaluation of Dimensional Stability and Surface Hardness of Interocclusal Recording Materials at Various Time Intervals: An in vitro Study.

Aim: At different timings, assessment and comparison of the dimensional stability and surface hardness of three interocclusal recording materials (IRM). Materials and
Methods: Samples of polyvinyl siloxane, ZOE, and bite registration wax were made using stainless steel die. Each group had 10 samples. At 1, 8, 24, and 48 h, the samples were estimated using a 10× amplification stereo microscope.
Results: Four readings were taken for each sample, the mean was considered to scale the dimensional change and surface hardness. At 1, 8, 24, and 48 h mean dimensional change was viewed as the most extreme among group 3 followed by group 2 and afterward group 1 (P < 0.05).
Conclusion: Polyvinyl siloxane was the steadiest, most precise, and had the most noteworthy surface hardness among the three interocclusal materials. Copyright:

INTRODUCTION

An interocclusal record is necessary to determine the exact maxilla–mandibular position. The records utilized for the edentulous and dentulous patients should be dependable with great strength and ought to be ready to imitate the specific maxilla–mandibular position in an articulator.[1] Materials utilized for maxilla–mandibular registration techniques and incorporate waxes, Zinc oxide eugenol (ZOE) paste, modeling compound, acrylic resin, plaster, and elastomeric materials, for example, polyether, polyvinyl siloxane.[2] In any case, in this study interocclusal records were made with polyvinyl siloxane, bite registration wax, and ZOE and looked at for their dimensional stability and surface hardness. Dimension stability of interocclusal recording materials (IRM) over the long run is of most extreme significance, as it guarantees a more exact representation of the patient's maxilla–mandibular relationship.[3] Henceforth, this in vitro study was conducted to assess the impact of time on dimensional stability and surface hardness of various interocclusal registration materials.

MATERIALS AND METHODS

The study was conducted in the Department of Prosthodontics, Rama Dental College Hospital and Research Centre, Kanpur, Uttar Pradesh, India (Ethical Clearance No. b02/IEC/RDCHRC/2020-21/). A barrel-shaped hardened stainless-steel die was made with an empty ring (height 31 mm, inner/outer diameter 30/38 mm ADA spec. no 19). Three lines were engraved on the die surface [Figure 1]. Lines A, B, and C with B crossing the middle, at a distance of 2.5 mm from the middle. Samples were made for Group 1, 2, and 3 with polyvinyl siloxane, ZOE [Figure 2], and bite registration wax, respectively (10 per group). For dimensional stability, the distance between two parallel lines A and C was measured using a stereomicroscope. Readings were recorded at 1, 8, 24, and 48 h. The mean between A and C in each case was compared to the related measurement. Shore hardness tester was used for surface hardness for all samples. The depth indication must be set to zero for testing the example specimen. For 3 s, a light push was applied to the indicator with the fingers, and then the unit was lowered onto the sample until the pressure foot was fully engaged. The mean value of four readings on four separate markings of the material was taken as final.

Figure 1

(a) Stainless-steel die with engravings (b) outer ring

Figure 2

ZOE paste samples (Group 2)

RESULTS

Table 1 shows, at 1 h mean dimension change for group 1 was 0.50190, for group 2 was 0.61000, and for group 3 was 0.71220. The overall analysis of variance (ANOVA) was <0.001. At 1 h interval, 1 vs. 2 showed a value of 0.964 thus it was statistically insignificant. At 1 h interval, 1 vs. 3 was statistically significant according to Turkey's test showing a value <0.001. Also, 2 vs. 3 was statistically significant according to Turkey's test showing a value <0.001. Table 2 shows that at 1 h interval mean surface hardness for group 1 was 76.20, for group 2 was 56.00, and for group 3 was 55.70. Overall ANOVA showed a value of <0.001. At 1 h interval, 2 vs. 3 showed a value of 0.987 (insignificant). At 1 h interval, 1 vs. 2 was statistically significant according to Turkey's test showing a value <0.001. Also, 1 vs. 3 was statistically significant according to Turkey's test showing a value <0.001.

Table 1

At different time intervals, the dimensions of three IRM were compared

Time	Group	Mean	SD	ANOVA	P, Post hoc pair-wise comparison using Tukey’s test
					1 vs. 2	1 vs. 3	2 vs. 3
1 h	G1	0.50	0.002	<0.001*	0.964	<0.001*	<0.001*
	G 2	0.61	0.077
	G 3	0.71	0.031
8 h	G 1	0.50	0.015	<0.001*	0.925	<0.001*	<0.001*
	G 2	0.60	0.070
	G 3	0.65	0.010
24 h	G 1	0.49	0.014	<0.001*	0.158	<0.001*	<0.001*
	G 2	0.50	0.076
	G 3	0.62	0.025
48 h	G 1	0.48	0.014	<0.001*	0.008*	0.008*	<0.001*
	G 2	0.58	0.730
	G 3	0.60	0.017

*Significant (p<0.05)

Table 2

At different time intervals, the surface hardness of three IRM were compared

Time	Group	Mean	SD	ANOVA	P, Post hoc pair-wise comparison using Tukey’s test
					1 vs. 2	1 vs. 3	2 vs. 3
1 h	G 1	76.20	2.530	<0.001*	<0.001*	<0.001*	0.987
	G 2	56.00	2.261
	G 3	55.70	6.617
8 h	G 1	78.80	1.398	<0.001*	<0.001*	<0.001*	0.637
	G 2	60.20	2.394
	G 3	58.10	8.465
24 h	G 1	78.00	1.563	<0.001*	<0.001*	<0.001*	0.290
	G 2	63.70	3.057
	G 3	59.80	9.211
48 h	G 1	78.20	1.398	<0.001*	<0.001*	0.028*	0.028*
	G 2	67.40	2.119
	G 3	61.00	8.667

*Significant (p<0.05)

DISCUSSION

The interocclusal record is utilized to transmit the interocclusal connection from the patient's oral cavity to the articulators, allowing the working casts and dies to be oriented to adjacent and opposing dental structures.[4] Surface hardness is affected by various factors such as load, nature of the load, and duration of load. More the hardness then it is easier to grind and shape the impression. Good hardness value provides ease of removal and insertion of impression from patient's oral cavities.[5] Dimensional stability is the property of the materials to maintain their original shape and form without undergoing any dimensional change. It depends upon the type of materials, surrounding factors such as temperature and time.[6] Interocclusal recording material made of polyvinyl siloxanes is the best choice as it is more accurate than others. However, this elastomeric impression has a spring to it that allows an articulated cast to open in the centric closure position, as well as a predetermined degree of resistance when inserting a stone framework into these recordings.[7]

CONCLUSION

Among all three materials, polyvinyl siloxane confirmed higher surface hardness and dimensional stability at all given times. Also, the dimensional stability and correctness of polyvinyl siloxane substances were statistically significant. At 1, 8, 24, and 48 h, ZOE demonstrated less dimensional change than bite registration wax.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.