Gingival health, plaque accumulation, and restoration outcomes in deciduous anterior teeth: evaluating zirconia crowns versus composite resin strip crowns.

BACKGROUND: Zirconia crowns, resembling crystals and with enamel-like aesthetics, are recent entrants in pediatric restorative dentistry. Despite growing use, their empirical efficacy remains under-explored. The aim of this study is to compare resin composite strip crowns and premanufactured zirconia crowns on primary maxillary incisors. METHODS: In the Pediatric Dental Clinics, 240 primary maxillary incisors (69 patients) were treated with either zirconia (120 teeth) or composite strip crowns (120 teeth). Evaluations of gingival health, plaque, secondary caries, restoration failure, and opposing teeth wear occurred at 3, 6, and 12-month intervals. RESULTS: At 3 months, zirconia crowns showed less gum bleeding (P=0.006) and plaque. Through 6 and 12 months, zirconia crowns exhibited fewer failures but higher opposing teeth wear. Strip crowns indicated greater tooth material loss. CONCLUSIONS: Zirconia crowns demonstrated superior gingival health and durability over composite resin strip crowns but caused increased wear on opposing teeth.

In vitro Evaluation of Laser vs. Handpiece for Tooth Preparation.

Background: The erbium-doped yttrium aluminium garnet (Er:YAG) laser has been revealed to effectively ablate dental hard tissues, and its utilisation to caries eradication and cavity preparation is envisaged. Nevertheless, only a limited research has been performed on the Er:YAG laser's capacity to treat caries. Aim and Objectives: The efficiency of caries elimination with an Er:YAG laser in vitro was equated to that of traditional mechanical therapy in this study. Methodology: The investigation made use of teeth that had suffered from root caries. The Er:YAG laser was used to treat half of each tooth, while the other half was either removed with a conventional bur or left untouched as a control. Each therapy was evaluated in terms of how long it took to remove cavities, histological examinations of decalcified serial sections, scanning electron microscopy (SEM) analyses and the density of the dentin. Result: A longer treatment time was required for the Er:YAG laser to completely eradicate carious dentin because of its precise irradiation strategy. However, the Er:YAG laser was effective in removing diseased and softening carious dentin with little heat injury to neighbouring intact dentin, much as the bur treatment. It was also shown that the Er:YAG laser treatment had a lower amount of vibration than other methods. The SEM study of the lased dentin surface revealed characteristic micro-irregularities. Conclusion: The Er:YAG laser system appears to be a potential novel technical option for caries therapy, based on our findings.

Analysis of surface conditioning methods on core-veneer bond strength of CAD/CAM zirconia restorations.

BACKGROUND: The increased strength of zirconia has resulted in its widespread application in clinical dentistry. Nevertheless, the fracture of veneering porcelains remains one of the key reasons of failure. OBJECTIVE: The objective of this study was to compare and analyze the influence of surface conditioning methods on the core-veneer bond strength of zirconia restorations. METHODS: Thirty specimens of zirconia core with sizes 10 × 5 × 5 mm were layered with porcelain of sizes 5 × 3 × 3 mm. On the basis of different surface conditioning methods, four groups were made: Group I: abrasion with airborne alumina particles of 110 µm size, Group II: sandblasting with silica coated alumina particles of 50 µm in size, Group III (modified group): alteration with a coating of zirconia powder prior to sintering, and Group IV (control group): metal core specimens. The shear force of all specimens was tested using a universal testing machine with a 0.5 mm/min crosshead speed. One-way analysis of variance (ANOVA) and Tukey's post hoc pair wise comparison (p= 0.05) were performed to analyze the shear bond strength. A scanning electron microscope was used to assess the fractured specimens. RESULTS: A statistically significant difference was noted between the groups. The mean value of shear bond strength was 40.25 MPa for Group I, 41.93 MPa for Group II, 48.08 MPa for Group III and 47.01 MPa for Group IV. CONCLUSIONS: The modified zirconia group and control group demonstrated a significantly higher mean bond strength than that of Group I, where airborne particle abrasion was used. The scanning electron microscope showed that cohesive fracture in the porcelain veneers was the main problem of failure in altered zirconia. The modified zirconia specimens in Group III demonstrated significantly improved values of shear bond strength.

Variations in the Compressive Strength of a Die Stone with Three Different Sulfates at Eight Different Concentrations: An In Vitro Study.

AIM: The present study aimed to evaluate the alteration in the compressive strength (CS) of the die stone with three different sulfate salt additives, each at eight various concentrations. MATERIALS AND METHODS: The specimens were prepared at specific dimensions (length: 2.5 cm and diameter: 2.5 cm) divided into three test groups based on the type of sulfate additives used [potassium sulfate (K2SO4), zinc sulfate (ZnSO4·H2O), and manganese sulfate (MnSO4·H2O)] and one control group, without any additives. Again, each group was divided into eight subgroups based on concentration of sulfates (ranging from 0.2% to 4%). A total of 375 specimens were tested. CS (in MPa) was evaluated after 72 hours of drying time, using an universal testing machine. STATISTICAL ANALYSIS: A one-way analysis of variance (ANOVA) was used for intergroup comparisons. Individual comparisons were done using the post hoc Tukey HSD analysis. RESULTS: All the three additives at all the concentrations have shown an inferior resistance to compressive forces when compared to the standard specimen. However, the least mean CS was observed at 0.8% of MnSO4 (10.95 MPa) and the highest was at 1% K2SO4 (25.28%). A highly significant difference (p < 0.001) was observed among the concentrations in all the three groups (K2SO4, MnSO4, and ZnSO4 groups) and F values were derived as 69.84, 24.29, and 130.52, respectively. At each concentration, comparisons between the groups have shown a significant difference (p < 0.05) at almost all concentrations. CONCLUSION: The CS of die stone is shown to be decreased with an increase in all three types of sulfate additives when compared to the control specimen. CLINICAL SIGNIFICANCE: Die stone is an often used gypsum material in the field of dentistry. Compressive strength of the die stone is crucial in prosthetic dentistry; chemical additives such as sulfate salts may increase the CS such that the die stone can withstand clinical and laboratory handling forces. How to cite this article: Vyas R, Vaddamanu SK, Gurumurthy V, et al. Variations in the Compressive Strength of a Die Stone with Three Different Sulfates at Eight Different Concentrations: An In Vitro Study. J Contemp Dent Pract 2019;20(11):1297-1306.