Purpose: This study evaluates the effects of artificial aging on the optical properties of high-translucent zirconia and lithium disilicate used for esthetic restorations. Materials and methods: About 36 disk-shaped specimens (10 mm diameter, 1 mm thickness) were fabricated from three materials: high-translucent zirconia (4Y-PSZ, Cercon^® ht, Dentsply Sirona; n = 12), extra-translucent zirconia (5Y-PSZ, Cercon^® xt, Dentsply Sirona; n = 12), and lithium disilicate (IPS e.max^® CAD, Ivoclar Vivadent; n = 12). Optical properties, including color change (ΔE), contrast ratio (CR), and translucency parameter (TP), were measured before and after artificial aging. Artificial aging was simulated by autoclaving specimens at 2 bar pressure and 134°C for 5 hours, equivalent to approximately 10–15 years of clinical aging. Data were tested for normality and expressed as mean ± standard deviation. Statistical analyses were conducted using parametric tests, with the significance level at p ≤ 0.05. Results: Lithium disilicate demonstrated the highest color stability following artificial aging (ΔE = 1.73 ± 0.16), outperforming high-translucent zirconia (4Y-PSZ, ΔE = 2.91 ± 0.23) and extra-translucent zirconia (5Y-PSZ, ΔE = 2.73 ± 0.30). It also exhibited the closest initial translucency to enamel (TP = 16.05 ± 0.12), significantly higher than 4Y-PSZ (TP = 11.99 ± 0.19) and 5Y-PSZ (TP = 13.59 ± 0.19). Artificial aging resulted in reduced translucency for all materials, with lithium disilicate showing the smallest decrease (ΔTP = –0.52 ± 0.17), compared to 4Y-PSZ (ΔTP = –1.01 ± 0.41) and 5Y-PSZ (ΔTP = –0.95 ± 0.31). These changes, although statistically significant, were likely clinically imperceptible. Conclusion: Lithium disilicate demonstrated superior resistance to artificial aging, maintaining better color stability and translucency compared to high- and extra-translucent zirconia. Its optical properties, closely resembling natural enamel, highlight its clinical advantage for long-term esthetic restorations. While aging-induced changes were observed in all materials, these were unlikely to be clinically perceptible.

Purpose: To evaluate the color stability and surface abrasion of nanoparticle-modified glass ionomer cement (GIC) with dentifrices. Materials and methods: Green-synthesized nanoparticle chitosan–titanium–zirconia–hydroxyapatite (Ch–Ti–Zr–HA) was prepared via a one-pot method and incorporated into conventional GIC at concentrations of 3, 5, and 10% (groups I, II, and III, respectively), with group IV serving as the control. Material characterization was done using a field emission scanning electron microscope (FESEM). Thirty-two disk-shaped specimens were used to evaluate color stability and gloss before and after simulated brushing. Additionally, 32 extracted molar teeth fulfilling the inclusion criteria were utilized for preparing class I cavities and restored according to group materials to assess surface abrasion. A toothbrush simulator (ZM3.8 SD Mechatronik) applied toothpaste under 3 N pressure for 30,000 cycles at 1.25 Hz, simulating approximately 6 years of brushing. Surface scans before and after brushing were analyzed using Geomagic software to measure root mean square (RMS), maximum deviation, and average deviation, providing quantitative data on abrasion levels. One-way ANOVA was done, followed by Tukey's post hoc test to determine significant differences between groups. Results: Group II (5%) nanoparticle-reinforced GIC exhibited the least color variation (0.499 ± 0.454) and had superior abrasion resistance with lower RMS deviation (0.073 ± 0.006), maximum deviation (0.668 ± 0.004), and average deviation (0.003 ± 0.001) values compared to all other groups (p < 0.05). Additionally, no significant (p > 0.05) change in gloss was observed when compared to the control group (2.13 ± 1.06). Conclusion: The 5% nanoparticle-modified GIC demonstrated minimal color change, exhibited the lowest abrasion deviation, and maintained gloss levels effectively, suggesting that it will be a promising material in providing long-lasting esthetic and functional outcomes for dental restorations. Further, the long-term performance under dynamic masticatory forces needs to be evaluated.

Purpose: To evaluate and compare peri-implant strain generated by polyetheretherketone (PEEK), zirconia, and porcelain-fused-to-metal (PFM) screw- and cement-retained implant-supported crowns using strain gauges. Materials and methods: A 4 × 12 mm implant (Dentium) was placed in a polymethyl methacrylate (PMMA) block. A prefabricated standard abutment was screwed onto the implant and scanned using a lab scanner. Thirty crowns for the three study groups (n = 10 each), namely PEEK, zirconia, and PFM, were fabricated and screwed onto the implant. Four strain gauges were bonded on the test block around the implant neck at buccal, lingual, mesial, and distal locations. An axial load of 250 N was applied in the center of the crown using a universal testing machine (UTM). Statistical analysis was performed using one-way analysis of variance (ANOVA) and Tukey honestly significant difference (HSD) test (p < 0.05). Results: One-way ANOVA revealed a significant difference (p < 0.001) among the groups. PEEK (1795.7 µε) showed significantly lower values of microstrain compared to zirconia (3110 µε) and PFM crowns (3435.9 µε). In all groups, strain was found to be higher on the buccal aspect, followed by the distal, lingual, and least in the mesial region. Conclusion: Peri-implant strain is influenced by the type of restorative material. PEEK significantly reduced the peri-implant strain relative to zirconia and PFM implant-supported crowns. PEEK may be a more biomechanically favorable material for implant-supported restorations, offering better stress distribution and reducing the risk of excessive peri-implant bone strain.

Purpose: To evaluate the water sorption and solubility of naturally obtained nano-hydroxyapatite (nano-HAp) incorporated into type 1 glass ionomer cement (GIC) and resin luting cements. Materials and methods: Hydroxyapatite synthesized from raw unfertilized eggshells via the co-precipitation technique was incorporated into type 1 GIC and resin cements. The eggshells were characterized using X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), energy-dispersive X-ray (EDAX), and Fourier transform infrared spectroscopy (FTIR). A total of 80 disk-shaped specimens were made from type 1 GIC (group A) and resin cements (group B). The specimens of group A (n = 40) were further divided into subgroups (n = 10 specimens each) based on the percentage of incorporation of nano-HAp: A1: Control (no nano-HAp incorporated); A2: 6% nano-HAp; A3: 8% nano-HAp; A4: 10% nano-HAp. Group B (n = 40) was subdivided (n = 10 specimens each) as follows: B1: Control (no nano-HAp incorporated); B2: 0.5% nano-HAp; B3: 1% nano-HAp; B4: 2% nano-HAp. The specimens were evaluated for water sorption and solubility. For intergroup comparisons, a one-way analysis of variance (ANOVA) was performed. Following that, Tukey's honestly significant difference (HSD) test was used for intragroup comparisons. Results: Nano-HAp synthesized from eggshells exhibited high crystallinity (up to 96%) with a particle size of 100–200 nm and the presence of phosphate, hydroxyl, and calcium ions. One-way ANOVA showed a significant difference in water sorption (p = 0.001) and solubility (p = 0.001) among group A and group B specimens. Type 1 GIC incorporated with 10% nano-HAp had the lowest water sorption (74.501 ± 2.00%) and solubility (24.833 ± 4.185%). Resin cements incorporated with 2% nano-HAp had the lowest water sorption (32.45 ± 1.73%) and solubility (15.943 ± 0.749%). Multiple comparisons of water sorption and solubility in group A and group B showed a significant difference (p = 0.001) between subgroups. Conclusion: Within the limitations of this study, it can be concluded that nano-HAp exhibited high crystallinity and a suitable particle size. The incorporation of nano-HAp enhanced the water sorption and solubility properties of type 1 GIC and resin-based luting cements. The addition of 10% nano-HAp in type 1 GIC and 2% nano-HAp in resin luting cement resulted in the most significant reduction in water sorption and solubility. Nano-HAp-modified GIC and resin cements may enhance marginal longevity, improve biocompatibility, prevent secondary caries, and provide esthetic and functional benefits.

Purpose: To investigate the effect of printing layer thickness on the color stability and surface roughness of three-dimensional (3D)-printed resin material. Materials and methods: A total of 45 specimens of interim crowns for the maxillary left central incisor were 3D printed using the D-Tech crown and bridge material. The specimens were fabricated and grouped (n = 15 each) in three different layer thicknesses: group I: 50 microns, group II: 75 microns, and group III: 100 microns. The specimens of each group were immersed in three different aging media (distilled water, tea, and carbonated drink) (n = 5 each). The color values were measured with a spectrophotometer at baseline and different time points (1, 15, and 30 days). The surface roughness (Ra) of resin specimens was measured by a perthometer. The statistical analysis was done using one-way analysis of variance (ANOVA) and a multiple comparison test. Intragroup comparison within each group was done using repeated ANOVA F-test followed by a Bonferroni post hoc test. Results: The greatest color stability was shown by 100-micron layer thickness samples immersed in different aging media (mean color change values in distilled water 1.915, tea 2.437, and carbonated drink 5.089) (p = 0.001). 50-micron layer thickness samples showed the least color stability (3.173, 3.551, and 6.023, respectively) (p = 0.001). Most discoloration of samples was seen when immersed in carbonated drink. Surface roughness decreased with a decrease in layer thickness (50 microns = 0.339) and increased with greater layer thickness (100 microns = 0.638) of the 3D-printed materials, and the difference was significant (p = 0.001). Conclusion: Within the limitations of the study, it was found that as the printing layer thickness increases, the color stability as well as the surface roughness of the 3D-printed resin material increases. In areas where esthetics are crucial, a thicker layer may be suggested for improved color stability. On the contrary, in regions prone to plaque buildup, a thinner layer might be recommended to reduce surface roughness.

Purpose: To compare and evaluate the accuracy and occlusal equilibrium of dynamically navigated implants in immediate extraction sockets with freehand immediate implant placement. Materials and methods: Patients requiring immediate implant placement were allocated into two groups: group I (immediate implants placed under dynamic navigation) and group II (immediate implants placed using freehand). A total of 30 implants were placed (n = 15) in each group. The placements of the immediate implants were carried out under dynamic guidance using Navident software. The deviations in placement were assessed by matching the planning data with the post-placement cone-beam computed tomography (CBCT) image. The linear and angular deviations were the primary outcome variables. Other outcome measures were occlusal equilibrium, operative complications, and prosthetic loading complications. Shapiro–Wilk's test was done to assess the normality of the data, and a t-test was used to assess the accuracy between the techniques. Other outcome parameters were represented in percentages. Results: The accuracy of planned and placement sites at the entry point was statistically significant (p = 0.05). The dynamic navigation group demonstrated superior accuracy, with a mean deviation of 0.92 ± 0.93 mm, compared to the freehand implant placement group (3.06 ± 1.3 mm). There was no statistically significant difference in the linear (dynamic navigation: 1.18 ± 0.92 mm; freehand: 2.6 ± 1.3 mm) and angular deviations (dynamic navigation: 1.5 ± 1.5°; freehand: 4.4 ± 4.1°). The most common surgical complication encountered was recalibration, occurring in 40% of cases. However, occlusal equilibrium analysis revealed no necessary adjustments to the crowns for implants placed using dynamic navigation. Conclusion: Within the limitations of the study, it can be concluded that dynamic navigation can serve as an alternative to freehand placement. It enhances implant placement accuracy, particularly in challenging immediate extraction sites where achieving the correct prosthetic position can be difficult. Immediate implant placements under dynamic navigation help in increasing the accuracy and reducing the offset forces.

Purpose: The purpose of this systematic review was to evaluate the success rate of resin-bonded fixed dental prostheses (RBFDPs) replacing the maxillary central incisor (MCI). Materials and methods: A systematic and manual search was performed in the PubMed, Scopus, and Cochrane Central Register of Controlled Trials (CENTRAL) databases. The prospective (PCS) and retrospective (RCS) cohort studies, as well as randomized controlled trials (RCTs) with an observation time of at least 2.5 years and providing quantitative clinical results on RBFDPs replacing MCI, were included. The focused question was, “Can absence of the maxillary central incisor be effectively treated by RBFDPs?” The Newcastle-Ottawa scale was used to assess the quality of the included cohort studies. However, the quality of the RCTs was assessed with version 2 of the Cochrane risk-of-bias tool (RoB 2). Results: Among 1,037 screened articles, four PCS and a single RCT were included in this review. All the RBFDPs replacing MCI evaluated in our studies were made of metal-ceramic material. The annual success rate of RBFDPs replacing MCI, calculated for each study, ranged from 88.3 to 97.3%. Of the 90 RBFDPs replacing MCI reported in the included studies, debonding was the most common complication of these restorations, with a relatively high rate (88%). The biological complications reported in this review were caries and periodontal pockets, with percentages of 8 and 4%, respectively. No meta-analysis was performed given the limited overall sample. Conclusion: Based on this study, the literature did not provide strong evidence to support or reject the reliability of RBFDPs for MCI replacement. Most of the included studies were PCS, and all included studies were judged to be of low quality with a high risk of bias. No study has evaluated all-ceramic RBFDPs, which currently represent the evolution in the setting of minimally invasive restorations. Additional and more in-depth investigations through well-designed RCTs are necessary to obtain more reliable and solid results.

Purpose: The purpose of the present systematic review was to assess the clinical survival and failure rates of lithium disilicate (LDS) veneers in the anterior region. Materials and methods: An electronic search was undertaken in June 2024, with the search carried out from 2010 to 2024. PubMed/Medline, Web of Science, and Scopus databases were searched. Patients rehabilitated with LDS veneers and with a minimum follow-up of 1 year were included. The cumulative survival rate (CSR) of veneers was calculated, considering fracture, debonding, and the need for endodontic treatment. Failure rates between preparations with or without incisal coverage, type of preparation design, and fabrication method were compared using the log-rank test (Kaplan–Meier). The risk of bias (RoB) assessment of studies was evaluated using ROB Software 2.0. Results: Sixteen studies were included with 5,891 LDS veneers. The 10-year estimated CSR of LDS veneers was 98.3%, when fracture, debonding, and the need for endodontic treatment were considered together as reasons for failure. The 10-year CSR for fracture was 98.3%, debonding was 99.3%, and the need for endodontic treatment was 99.6%. LDS veneers with butt joint preparations had a higher failure rate than veneers with incisal coverage. Feather/knife-edge preparations had a higher success rate than chamfer preparations. Computer-aided design and computer-aided manufacturing (CAD/CAM) milled and heat-pressed methods both provided superior quality restorations with increased survival (99%) in milled restorations. Conclusion: Within the limitations of the study, it can be concluded that the 10-year estimated CSR of LDS veneers was 98.3%, when fracture, debonding, and the need for endodontic treatment were considered as reasons for failure. This proves the point that LDS material can be used as a veneer material in the long term with improved esthetic and quality restorations.