Assessment of Adaptability and Linear Dimensional Changes of Two Heat Cure Denture Base Resin with Different Cooling Techniques: An In Vitro Study.

AIM: The current study was designed to assess the linear dimensional changes and adaptability of two heat-cured denture base resins using various cooling methods. MATERIALS AND METHODS: To prepare a total of 90 acrylic resin samples (45 acrylic resin samples for each material), four rectangular stainless-steel plates measuring 25 × 25 × 10 mm were fabricated. For both groups, the material was put into the mold at the dough stage. Group I - SR Triplex Hot Heat Cure acrylic; group II - DPI Heat Cure acrylic. Both groups used the same curing procedure. One of the following three techniques was used to cool the material (15 samples from each material) once the curing cycle was finished: (A) water bath, (b) quenching, and (C) air. A traveling microscope was used to measure the distance between the markings on the acrylic samples. The data was recorded and statistically analyzed. RESULTS: In SR Triplex Hot heat cure acrylic material, the maximum linear dimensional changes were found in the quenching technique (0.242 ± 0.05), followed by the air technique (0.168 ± 0.11) and the least was found in the water bath technique (0.146 ± 0.01). In DPI Heat Cure acrylic material, the maximum linear dimensional changes were found in the quenching technique (0.284 ± 0.09), followed by the air technique (0.172 ± 0.18) and the least was found in the water bath technique (0.158 ± 0.10). There was a statistically significant difference found between these three cooling techniques. On comparison of adaptability, the water bath technique, the marginal gap SR Triplex Hot was 0.012 ± 0.02 and DPI Heat Cure was 0.013 ± 0.02. In the quenching technique, the marginal gap SR Triplex Hot was 0.019 ± 0.04 and DPI Heat Cure was 0.016 ± 0.04. In the air technique, the marginal gap SR Triplex Hot was 0.017 ± 0.01 and DPI Heat Cure was 0.019 ± 0.01. CONCLUSION: The present study concluded that among the different cooling methods, the water bath technique had the least linear dimensional change, followed by the air and quenching techniques. When comparing the materials, DPI Heat Cure acrylic resin showed a greater linear dimensional change than SR Triplex Hot heat cure acrylic resin. CLINICAL SIGNIFICANCE: During polymerization, heat-cured acrylic resins experience dimensional changes. Shrinkage and expansion are dimensional changes that occur in heat-cured acrylic resins and have an impact on the occlusal relationship and denture fit. However, the denture base's material qualities and the different temperature variations it experiences during production may have an impact on this. How to cite this article: Kannaiyan K, Rathod A, Bhushan P, et al. Assessment of Adaptability and Linear Dimensional Changes of Two Heat Cure Denture Base Resin with Different Cooling Techniques: An In Vitro Study. J Contemp Dent Pract 2024;25(3):241-244.

Efficacy of Different Gingival Displacement Materials in the Management of Gingival Sulcus Width: A Comparative Study.

AIM: The aim of this study was to assess the effectiveness of different gingival displacement materials in the management of the width of the gingival sulcus. MATERIALS AND METHODS: Totally, 60 participants who were aged 18 years and more were chosen for this study. The eligible participants were those who required fixed prosthesis with at least one abutment. A modified sectional tray was used to make impressions with elastomeric materials along with additional polysilicon using the double mix single impression technique. All participants were divided randomly into three experimental groups with each group having 20 participants as follows: group I-Expasyl, group II-Magic Foam Cord, and group III-Traxodent. Soon after retraction, impressions were made and assessed in a comparable manner to pre-retraction impressions. Image analysis software was used to measure the quantity of displacement of the gingiva, marked as the distance from the tooth to the gingival crest in the horizontal level under stereomicroscope. RESULTS: The highest mean sulcular gingival width (0.644 ± 0.22) was found in Traxodent group followed by Expasyl group (0.590 ± 0.11) and Magic Foam Cord group (0.528 ± 0.01). A statistically significant difference (p<0.001) was found between the groups. Intergroup comparisons between the gingival displacement materials showed a statistically significant difference (p<0.05) between group II and group III. CONCLUSION: The present study concluded that all three gingival displacement materials lead to gingival displacement, which is needed for impression making. Slightly more retraction was seen in the Traxodent group when compared to the Expasyl group and Magic Foam Cord group. CLINICAL SIGNIFICANCE: The success of fixed prosthodontic treatment depends upon precision and accuracy in every step involved in the procedure.One of the most vital stepsis making precise impressions in relation to dimensional accuracy, tear strength, etc. It is essential to have an adequate thickness of the impression material along the margins to avoid distortion. This objective can be achieved by acceptable gingival retraction.

Effect of Acidic Beverages on Color Stability and Microhardness of Various Esthetic Restorative Materials: A Comparative Study.

AIM: The aim of this study was to assess the effect of acidic beverages on color stability and microhardness of various esthetic restorative materials. MATERIALS AND METHODS: A total of 60 samples were included in the present study. Group I: Microhybrid composite resin, Group II: Nanoceramic, Group III: ORMOCER (Organically Modified Ceramics). 10 mm internal diameter and 5 mm depth of cylindrical aluminum mold of were utilized to prepare the samples. All the esthetic restorative samples were submerged for 10 min in 25 ml of acidic drink (Coca-Cola) each day up to 15 days. Vickers diamond intender was used to measure the microhardness of each sample. These values were calculated with baseline, 7th, and 15th days for final microhardness values. RESULTS: The mean surface microhardness of 63.20 ± 0.46 was shown by Group III which was slightly more than that in Group II (60.08 ± 0.34) and Group I (58.10 ± 1.76). Analysis of covariance did not show any statistically significant difference between the groups. The samples in Group I showed the highest reduction in surface microhardness value after immersion into acidic drink, followed by Group II and Group III on 7th day and 15th day. A statistically significant difference (P < 0.001) was found on the 7th day. CONCLUSION: The present study concludes that the Organically Modified Ceramics esthetic restorative material showed the finest behavior after being dipped in the acidic drink followed next by Nanoceramic and Microhybrid composite resin.

Geometry of Implant Abutment Surface Improving Cement Effectiveness: An In vitro Study.

AIM: The aim of the study was to investigate whether the surface geometry or topography of implant abutments affects the retentive strength of prosthesis cemented with zinc phosphate on standard machined, sandblasted, and grooved implant abutments and to compare the results between them. MATERIALS AND METHODS: Fifteen similarly shaped implant abutments (MDcpk61; MIS Implant Technologies Ltd.,) (height 6.0 mm and 6-degree taper) were divided into three groups (n = 05): Group I - standard machined abutments without grooves, Group II - sandblasted abutments (same as Group I but sandblasted with 50 µ aluminum oxide), and Group III - abutment with prefabricated circumferential grooves. Further in these groups of 15 abutments, 5 abutments each are to be taken to check the retentive force of zinc phosphate cement. Fifteen identical cast copings was prepared to fit all 15 abutments. The castings will be cemented to each group of abutments with an above-mentioned luting agent. After thermal cycling and storage for 6 days in a water bath, a retention test is to be done with a tensile testing machine (Instron) (5 mm/min) and retentive forces will be recorded. Data will be subjected to one-way ANOVA test and Student's t-test. RESULTS: For zinc phosphate cement, F = 30.53 (>3.59 for P = 0.05) shows a statistically significant difference between all the three groups. CONCLUSION: Circumferential grooves on implant abutments give better retention when compared with standard machined (plain) and sandblasted abutments despite marked difference. CLINICAL SIGNIFICANCE: Retention of restoration depends on the surface of the abutment as well as the luting agents used. Incorporation of retentive grooves can enhance retention of prosthesis, especially in situation of short abutments.