Setting characteristics of vinyl-polysiloxane interocclusal recording materials

In Vitro Assessment of Dimensional Accuracy of Three Different Types of Interocclusal Recording Materials

AIM

The aim of the current study was to evaluate the dimensional accuracy of three various interocclusal recording materials.

MATERIALS AND METHODS

A total of 90 disc-shaped samples were prepared using polyether paste, wax, and polyvinyl siloxane material with the support of stainless steel die. For the purposes of this investigation, three frequently utilized interocclusal recording materials were chosen, and 30 samples from each material were prepared. Group I: Bite registration using polyether paste; Group II: Bite registration using wax; Group III: Bite registration using polyvinyl siloxane material. No samples were exposed to direct sunlight during storage and were kept at room temperature. Using a 10x universal measuring microscope, each sample disc was examined for the presence of horizontal and vertical lines inscripted in the die. For each of the samples, readings were taken at different time periods of 24, 48, and 72 hours.

RESULTS

After 24 hours, the less dimensional changes were found in polyether paste group (0.11 ± 0.07) followed by polyvinyl siloxane material group (0.19 ± 0.04) and wax group (0.25 ± 0.12). After 48 hours, the less dimensional changes were found in polyether paste group (0.34 ± 0.02) followed by polyvinyl siloxane material group (0.42 ± 0.01) and wax group (0.94 ± 0.12). After 72 hours, the least dimensional changes were found in polyether paste group (0.46 ± 0.14) followed by polyvinyl siloxane material group (0.92 ± 0.03) and wax group (1.14 ± 0.09).

CONCLUSION

The present study concluded that both the material and time factors had an impact on dimensional stability. The most dimensionally stable group was the polyether paste group, which was followed by the polyvinyl siloxane and wax material groups.

CLINICAL SIGNIFICANCE

Interocclusal recording material records the occlusal connection between real or artificial teeth for occlusal rehabilitation planning and for creating removable and fixed dentures. The creation of a clinically acceptable prosthesis is dependent upon the accuracy of the patient's diagnostic or working casts and the interocclusal record. How to cite this article: Sonkesriya S, Subramanian D, Saha P, et al. In Vitro Assessment of Dimensional Accuracy of Three Different Types of Interocclusal Recording Materials. J Contemp Dent Pract 2023;24(12):936-939.

The effect of different implant impression splinting techniques and time on the dimensional accuracy: An in vitro study

Splinting of impression copings is generally recommended for more complex implant-supported restorations. It can also be used in the digital workflow when the control model is needed to improve the fit of the prosthesis. However, there is a lack of knowledge on how dimensional accuracy is affected by different splinting techniques and time factors.

OBJECTIVES

To evaluate the time factor on the dimensional stability of different implant impression splinting strategies used in the conventional and digital workflow.

MATERIALS AND METHODS

Ten pairs of implant analogs were fixed to a stainless steel bar. Modified impression copings were connected to the analogs and eight splinting strategies evaluated (n=10): 1) type I impression plaster (PLA), 2) autopolymerizing acrylic resin, cut and rejoin technique (PTR), 3) light-cured acrylic resin, cut and rejoin technique (ILC), 4) light-cured acrylic resin, no cutting and rejoining (ILN), 5) VPS bite registration material (SBR), 6) bis-acryl bite registration material (LXB), 7) bis-acryl composite resin (PTP), 8) 3D printed splint (3DP). In each group, the position of modified impression copings was scanned with an accurate laboratory scanner at different time points: 1) unsplinted impression copings (baseline), 2) 2 hours after splinting, 3) 24 hours after splinting. Modified impression coping design allowed using metrology software to measure and compare distance, vertical, angle and rotational deviations between impression copings.

RESULTS

All types of splints showed dimensional deviations. After 2 hours of splinting, the lowest distance deviation was recorded in PTR (15.4±6.15µm), vertical deviation - in ILC (19.2±27.37µm), angle deviation - in ILC (0.08±0.1°), rotation - in LXB (0.2±0.24°) groups. Comparing results 2 and 24 hours after connection of impression copings, statistically significant deviations in the distance were recorded in groups PLA (-5.6±5.95 µm), PTR (5.5±7.01µm), ILN (19.2±14.26µm), PTP (23.8±12.55µm).

CONCLUSION

The best dimensional accuracy was observed in the ILC group, followed by PTR and 3DP groups.

CLINICAL SIGNIFICANCE

Proper selection of splinting technique and polymerization time can increase the accuracy of conventional or digital impressions. Splinting techniques with rigid materials, proper polymerization and compensating for material shrinkage produce the best results.

A maxillomandibular record for a removable partial denture by using polyvinyl siloxane and the metal framework: A dental technique

The accuracy of the maxillomandibular record influences the relationship of the definitive cast and therefore the success of a prosthesis. This article describes a technique in which polyvinyl siloxane is used to both stabilize a removable partial denture on the edentulous ridge and being the recording material itself. The technique is practical and time efficient, allowing the clinician to perform this step in a single appointment.

The effects of cross-linking agent and surfactant on the tear strength of novel vinyl polysiloxane impression materials

OBJECTIVES

To formulate experimental hydrophobic and hydrophilic vinyl polysiloxane (VPS) impression materials ab initio, comprising a novel cross-linking agent, tetra-functional (dimethylsilyl) orthosilicate (TFDMSOS), and a non-ionic surfactant, Rhodasurf CET-2 (ethoxylatedcetyl-oleyl alcohol), and to investigate their effects on tear strength (TS).

METHODS

Five experimental formulations (Exp I-V) were prepared and compared with three medium bodied commercial VPS impression materials (Aq M, Elt M, Extr M). Tear test was performed on trouser test specimens (n=12 per material), at four time points (immediately, 24, 72 and 168 hours after setting). FTIR spectroscopy was used for identifying functional bonds and cross-linking. The results were analysed with one-way ANOVA, two-way ANOVA and post hoc Tukey's test using the SPSS PASW statistical 22 software.

RESULTS

The material with novel cross-linking agent (Exp II) had significantly higher TSs at all-time points compared to Exp I (control; p˂0.05). Materials incorporating both TFDMSOS and surfactant (Exp III, IV and V), had further significantly increased TS at all-time points, which were concentration dependent. Extr M had a significantly lower TS (immediately after setting and at 24 hours) compared to all Exp and other commercial materials, with the exception of Elt M (difference not significant). The TSs of Exp II-V, after 72 and 168 hours, were significantly higher for than all commercial products and Exp I. FTIR spectra showed the consumption of Si-H groups indicating crosslinking had taken place with the addition of TFDMSOS and surfactant which contributed to an increase in the TS.

SIGNIFICANCE

TFDMSOS cross-linking agent increased the TS of Exp II significantly at all-time points compared to the control. Novel surfactant further significantly increased TS, and it was also concentration dependent. Exp VPS with improved TS have been developed, addressing one of the drawbacks of commercial VPS materials.

Three-Dimensional Accuracy of Digital Static Interocclusal Registration by Three Intraoral Scanner Systems

PURPOSE

Prior studies have defined the accuracy of intraoral scanner (IOS) systems but the accuracy of the digital static interocclusal registration function of these systems has not been reported. This study compared the three-dimensional (3D) accuracy of the digital static interocclusal registration of 3 IOS systems using the buccal bite scan function.

MATERIALS AND METHODS

Three IOS systems compared were 3M^TM True Definition Scanner (TDS), TRIOS Color (TRC), and CEREC AC with CEREC Omnicam (CER). Using each scanner, 7 scans (n = 7) of the mounted and articulated SLA master models were obtained. The measurement targets (SiN reference spheres and implant abutment analogs) were in the opposing models at the right (R), central (C), and left (L) regions; abutments #26 and #36, respectively. A coordinate measuring machine with metrology software compared the physical and virtual targets to derive the global 3D linear distortion between the centroids of the respective target reference spheres and abutment analogs (dR_R , dR_C , dR_L , and dR_M ) and 2D distances between the pierce points of the abutment analogs (dX_M , dY_M , dZ_M ), with 3 measurement repetitions for each scan.

RESULTS

Mean 3D distortion ranged from -471.9 to 31.7 μm for dR_R , -579.0 to -87.0 μm for dR_C , -381.5 to 69.4 μm for dR_L , and -184.9 to -23.1 μm for dR_M . Mean 2D distortion ranged from -225.9 to 0.8 μm for dX_M , -130.6 to -126.1 μm for dY_M , and -34.3 to 26.3 μm for dZ_M . Significant differences were found for interarch distortions across the three systems. For dR_R and dR_L , all three test groups were significantly different, whereas for dR_C , the TDS was significantly different from the TRC and CER. For 2D distortion, significant differences were found for dX_M only.

CONCLUSIONS

Interarch and global interocclusal distortions for the three IOS systems were significantly different. TRC performed overall the best and TDS was the worst. The interarch (dR_R , dR_C , dR_L ) and interocclusal (dX_M ) distortions observed will affect the magnitude of occlusal contacts of restorations clinically. The final restoration may be either hyperoccluded or infraoccluded, requiring compensations during the CAD design stage or clinical adjustments at issue.

A Comparative Study to Evaluate the Compression Resistance of Different Interocclusal Recording Materials: An In Vitro Study

Recording and transferring of accurate existing occlusal records is of prime importance for a successful restoration. An ideal occlusal registration material should provide minimal resistance to mandibular closure during the registration of maxillomandibular relationships. Interocclusal bite registration materials are partly responsible for accurate precision and occlusal quality of final prosthetic restorations when used for mounting casts on the articulators. The aim of selecting this study is to compare different types of recent interocclusal recording materials and to find the best among them which can resist a constant compressive load and will give the least inaccuracies. In the present study compressive resistance of four interocclusal recording materials viz. Imprint bite, Vitual refill, Jet bite and Ramitec at various thickness (2, 5, 10 and 20 mm) when subjected to a constant compressive load of 25 N was studied. The thickness of the interocclusal recoding materials were selected to simulate various clinical situations. For standardization, the specimens were stored at room temperature for 24 h to simulate the time between clinical and laboratory phases, N = 20 specimens from each group was selected (making a total sample size of N = 80). The SPSS version 17 has been used, two way ANOVA was applied to compare different types of recent interocclusal recording materials, p value ≤0.05 was considered statistically significant. A total of 80 samples were fabricated. Results of two-way analysis of variance (p ≤ 0.05) indicated that there was a significant difference in compressive resistance among the materials of each thickness. The 2 mm thickness specimens showed the least compression and 20 mm thickness specimen showed maximum compression under a constant load of 25 N for all the four materials tested. Virtual Refill bite registration material showed the least compression value than Imprint bite polyvinylsiloxane registration material, Ramitec polyether bite registration material and Jet bite polyvinylsiloxane registration material with negligible error of 0.04 mm found in 2 mm thickness. The results of foregoing study showed that Virtual refill having greater resistance to compression than other interocclusal recording material at various thickness. It exhibit minimal distortion during compression and give clinician the opportunity to make only minimal adjustments to the restorations that were delivered from the laboratory and avoid unnecessary use of chairtime, or repetition of some clinical and technical stages.

Color and structural changes of a maxillofacial elastomer: the effects of accelerated photoaging, disinfection and type of pigments

PURPOSE

The aim of this study was to investigate the color and structural changes of a maxillofacial silicone colored with 2 different pigments, after photoaging and immersion in disinfectants.

METHODS

Ninety-six cylindrical specimens were fabricated and divided into 3 equal groups. The specimens of the first group consisted of unpigmented silicone (Multisil Epithetik), those of the second group consisted of unpigmented silicone, colored with red functional liquid pigment (Cosmesil Reactive 0.2% wt). The specimens of the third group were fabricated using unpigmented silicone colored with red powder pigment Cosmesil Dry at 0.2% wt. Specimens of each group were divided into 4 equal subgroups (immersed in soap solution, ethanol 95° or distilled water or placed in a photoaging apparatus for 174 hours). Structural changes were examined by infrared spectroscopy (ATR-FTIR) before and after aging. Color changes (ΔΕ*) were measured using the CIE L*a*b* system. Two-way ANOVA and Tukey's test for post hoc comparison were used at a = 0.05.

RESULTS

Infrared spectroscopy showed no structural changes after immersion in solutions and photoaging, for all the materials tested. No statistically significant differences for ΔΕ* among the tested groups were found.

CONCLUSIONS

It can be concluded that no structural changes of pigmented and unpigmented silicone elastomers were observed among all aging procedures. Recorded color changes for the materials tested were within the limits of clinical acceptability after all aging procedures. Immersion in distilled water presented the best color stability, whereas photoaging, the poorest, for all materials.