The effect of aging on the translucency of contemporary zirconia generations: in-vitro study.

BACKGROUND: The translucency of different zirconia generations at each time point after thermocycling aging is still lacking. METHODS: Four zirconia materials were used with a total of 60 samples produced from monolithic third generation (5Y) 5 mol% yttria-stabilized zirconia polycrystalline ceramic and fourth generation zirconia (4Y) 4 mol% yttria-stabilized zirconia polycrystalline ceramic, represented by [group1:[CM-5Y] Ceramill Zolid fx (3rd generation zirconia) (Amann Girrbach, Koblach, Austria), group 2:[CM-4Y] Ceramill Zolid HT + (4th generation zirconia) (Amann Girrbach, Koblach, Austria), group 3:[CC-5Y] Cercon XT/ML (Dentsply Sirona, Germany) (3rd generation), and group 4:[CC-4Y] Cercon HT/ML (Dentsply Sirona, Germany) (4th generation)]. The L*a*b* figures were measured by using a spectrophotometer at baseline and after 10,000, 30,000, and 50,000 cycles of thermocycling. At each interval, the translucency of the samples was estimated by using the translucency formula CIEDE2000. The Scheffe post-hoc compared differences among each of the four materials. The Repeated measures ANOVA tested the differences between the materials at each of the different thermocycling intervals (p < .001). Data analyses were evaluated at a significance level of p < .05 (CI 95%). RESULTS: Two-way ANOVA revealed that at baseline the third and fourth generation's zirconia showed statistically significant differences in translucency (P < .001). Translucency values at baseline and after thermocycling exhibited statistically significant changes (p = .003). At each of the time interval; CM-4Y had the highest translucency values followed by CM-5Y, CC-4Y and CC-5Y had the least translucency values. CONCLUSIONS: The third and fourth generations of zirconia displayed different translucencies. Thermocycling affected the translucency of both third and fourth generations of zirconia. At each of the time intervals group 2:[CM-4Y] had the highest TP followed by group1:[CM-5Y], while, group 3:[CC-5Y] and group 4:[CC-4Y] had the least TP.

Novel Variants Linked to the Prodromal Stage of Parkinson's Disease (PD) Patients.

BACKGROUND AND OBJECTIVE: The symptoms of most neurodegenerative diseases, including Parkinson's disease (PD), usually do not occur until substantial neuronal loss occurs. This makes the process of early diagnosis very challenging. Hence, this research used variant call format (VCF) analysis to detect variants and novel genes that could be used as prognostic indicators in the early diagnosis of prodromal PD. MATERIALS AND METHODS: Data were obtained from the Parkinson's Progression Markers Initiative (PPMI), and we analyzed prodromal patients with gVCF data collected in the 2021 cohort. A total of 304 participants were included, including 100 healthy controls, 146 prodromal genetic individuals, 21 prodromal hyposmia individuals, and 37 prodromal individuals with RBD. A pipeline was developed to process the samples from gVCF to reach variant annotation and pathway and disease association analysis. RESULTS: Novel variant percentages were detected in the analyzed prodromal subgroups. The prodromal subgroup analysis revealed novel variations of 1.0%, 1.2%, 0.6%, 0.3%, 0.5%, and 0.4% for the genetic male, genetic female, hyposmia male, hyposmia female, RBD male, and RBD female groups, respectively. Interestingly, 12 potentially novel loci (MTF2, PIK3CA, ADD1, SYBU, IRS2, USP8, PIGL, FASN, MYLK2, USP25, EP300, and PPP6R2) that were recently detected in PD patients were detected in the prodromal stage of PD. CONCLUSIONS: Genetic biomarkers are crucial for the early detection of Parkinson's disease and its prodromal stage. The novel PD genes detected in prodromal patients could aid in the use of gene biomarkers for early diagnosis of the prodromal stage without relying only on phenotypic traits.

Influence of Ceramic Materials and Preparation Designs on the Marginal Adaptation of Inlays and Onlays after Thermocycling.

PURPOSE: The aim of the current study is to evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intra-coronal preparation designs. MATERIALS AND METHODS: An examination of the marginal adaption of two materials, lithium disilicate (IPS e.max CAD) (EX) and polymer infiltrated ceramic network material (PICN; Vita Enamic) (EN), and two preparation designs where D1 represents MOD inlay preparation with no cusp reduction and D2 in addition of the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. 4 sub-groups (EX-D1), (EX-D2), (EN-D1), (EN-D2) were conducted. Forty (n=40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, standard deviation (Sd), minimum, maximum, and 95% confidence interval. Pair-wise comparisons using Tukey's Post-Hoc test were performed following a significant analysis of variance (ANOVA) P ≤ 0.05. RESULTS: The results revealed that lithium disilicate (IPS e.max CAD) showed statistically significantly higher mean gap distance than polymer infiltrated ceramic network material (PICN; Vita Enamic) (61µm to 99µm). Pair-wise comparisons showed that D2 design has statistically significant higher mean gap values than D1. CONCLUSIONS: Both lithium disilicate (IPS e.max CAD) or polymer infiltrated ceramic network material (PICN; Vita Enamic) provided marginal adaptation within clinical accepted range. Polymer infiltrated ceramic network material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional Preparation.

Color stability of two different resin matrix ceramics: randomized clinical trial.

BACKGROUND: One of the most common causes of aesthetic failure and restoration replacement is the tooth restorations color mismatch specifically after aging. METHODS: One hundred and two participants with endodontically treated first molar were selected clinically. The patients were randomly splited into two groups and restored either with Cerasmart hybrid ceramic or Vita Enamic polymer infiltrated ceramic network (PICN) crowns and cemented using dual cure adhesive cement. The color difference (ΔE) values after cementation at 0 (Baseline), 6, and 12 months of use were obtained by quantification of L*, a*, and b* values with a digital spectrophotometer. Mann-Whitney test used to compare between tested groups at each time point and between (α = 0.05). RESULTS: At 6 months follow-up intervals, Vita Enamic group showed the highest significant ∆L* (p = 0.035) and ∆a* (p < 0.001) compared to Cerasmart group. ∆b* and ∆E showed no significant difference between both groups (p > 0.05). Furthermore, all color parameters of both groups showed statistically significant difference at 12 months follow-up intervals. After 12 months, Vita Enamic restorations presented higher color change compared to Cerasmart restorations with a (p-value of 0.0120). When comparing the total color difference ∆Et through-out the follow-up intervals of Vita Enamic & Cerasmart groups, there were insignificant difference (p = 0.263). CONCLUSION: Both hybrid materials demonstrated comparable color stability after 1 year of clinical service within clinical acceptance range. However, Cerasmart demonstrated a better colour stability after 1 year. TRIAL REGISTRATION: ClinicalTrials.gov (ID: NCT05501808) 15/8/ 2022- 'retrospectively registered'.

The Effect of Platform-Switching Implants and Different Abutment Materials on the Stress Distribution of Implant-Supported Restorations.

The purpose of this study was to evaluate the effect of implant platform-switching design and abutment materials on the stress distribution around implants. Implants were fixed in epoxy-resin models restoring posterior missing first molars, representing two main groups according to the implant-abutment connection. Each group was subdivided according to the type of abutment material used (titanium or zirconia). Twenty monolithic fully anatomical zirconia crowns were fabricated. Stress analysis was measured around the implants using strain gauges during the static loading of each implant-supported crown. Data were collected, tabulated, and statistically analyzed. Standard implant-abutment connection groups recorded the highest (statistically significant; P < .05) mean strain values compared to platform-switching connection groups. Abutment materials in both groups recorded statistically nonsignificant (P > .05) mean strain values. The platform-switching concept showed better crestal-bone stress distribution around implant-supported restorations. Abutment materials expressed no statistically significant effect on the stress distribution around implant-supported restorations. Zirconia and titanium abutments could withstand the functional loads developed during physiologic chewing in the molar area.