Analysis of the effect of thermocycling on bonding cements to zirconia.

Objective: The aim of this study was to evaluate the effect of thermocycling on shear bond strength (SBS) of several resin cement materials to different types of zirconia dental ceramics. Materials and Methods: 120 square shaped disc specimens were fabricated using two types of zirconia blocks (Sagemax and Sirona). Each zirconia group was divided into three sub-groups based on the resin cement bonded to the specimens. Three different self-adhesive resin cements were used (Calibra, Breeze and RelyX). The specimens were further grouped into experimental and control groups (n = 10). The experimental specimens were exposed to a thermo-cycling protocol of 1500 cycles in water bath at 5c and 55c. Specimens were then stored at 37c for 24 h then all specimens underwent SBS test with an Instron machine. Mode of failure was inspected visually and microscopically. Data were statistically analyzed using multivariate analysis of variance followed by one-way analysis of variance, Tukey's multiple comparison test, student's t-test for independent samples were used to compare the mean values of SBS in relation to the categorical study variables. Results: The mean SBS values of experimental groups were significantly lower than control groups for all the 6 combinations of Zirconia and cement types (p < 0.0001). The higher mean difference (14.29 MPa) was observed in the combination of Sagemax and Rely-X. Rely-X displayed the highest SBS among all the cements while no significant difference was found in mean SBS values of Calibra and Breez cements in all groups. The mean SBS values of Sagemax zirconia were significantly higher than the Sirona with all three types of cements (p < 0.0001) within control groups. Microscopic and visual analysis demonstrated a majority of adhesive mode of failure. Conclusion: Thermocycling significantly reduced the SBS between the zirconia materials and self-adhesive resin cements tested. The amount of reduction varies according to cement and zirconia types.

Synergistic effect of graphene oxide/calcium phosphate nanofiller in a dentin adhesive on its dentin bond integrity and degree of conversion. A scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared, micro-Raman, and bond strength study.

The objective was to formulate and analyze a dentin adhesive incorporated with graphene oxide (GO) nanoparticle and calcium phosphate (CaP) composite. Methods comprising of scanning electron microscopy (SEM)-energy dispersive X-ray spectroscopy (EDX), micro-Raman spectroscopy, shear bond strength (SBS), and Fourier transform infrared (FTIR) spectroscopy were used to characterize nanoparticle composite, dentin bond toughness, degree of conversion (DC), and adhesive-dentin interaction. Postsynthesis of GO nanoparticles, they were functionalized with CaP using standard process. The GO-CaP composite was not added to experimental adhesive (negative control group, GO-CaP-0%), and added at 2.5 and 5 wt% to yield GO-CaP-2.5% and GO-CaP 5% groups, respectively. Teeth were set to form bonded samples utilizing adhesives in three groups for SBS testing, with and without thermocycling. The homogenous diffusion of GO-CaP composite was verified in the adhesive. Resin tags having standard penetrations were observed on SEM micrographs. The EDX analysis confirmed the occurrence of calcium, phosphorus, and carbon ions in the composite containing adhesives. The SBS test revealed highest mean values for GO-CaP-5% followed by GO-CaP-2.5%. The FTIR spectra verified the presence of apatite peaks and the micro-Raman spectra showed characteristic D and G bands for GO nanoparticles. GO-CaP composite in dentin adhesive may improve its bond strength. The addition of 5 wt% resulted in a bond strength that was superior to all other groups. GO-CaP-5% group demonstrated lower DC (to control), uniform distribution of GO and CaP composite within adhesive, appropriate dentin interaction, and resin tag formation.

Micro-computed tomography analysis of gap and void formation in different prefabricated fiber post cementation materials and techniques.

OBJECTIVE: The study was built around the objective of determining the variances in the gap and void formation around cemented prefabricated fiber posts with two different cementation materials and techniques with micro-computed tomography (µCT). METHODS: Standardized acrylic resin roots (N = 40) with prefabricated fiber posts (RelyX™ Fiber Post 3D) were split into four sets (n = 10) based on many types of cementation materials and techniques. In the first group, resin cement (RelyX™ Unicem) was inserted to the canals via root canal tips. In the second group, the same cement was injected, and a microbrush was used to distribute the cement inside the canal. In the third group, dual polymerizing resin cement (MultiCore® Flow) was injected into the canals by using root canal tips. In the fourth group, the same cement was injected, and a microbrush was used to distribute the cement inside the canal. The gap and void formation in the cement and the root canals was evaluated with µCT. IBM SPSS Statistics was used to perform the statistical evaluation, then the Kolmogorov-Smirnov test of normality and Kruskal-Wallis H test to compare these variables with respect to the all groups significant difference (a = 0.05). RESULTS: The study outlined no difference of significance when evaluating the gap and void formation within the experimental groups (P > 0.05). CONCLUSION: There was a certain amount of void and gap formation inside all of the tested specimens. However, no significant variances were found.

Clinical and radiographic peri-implant health status around narrow diameter implant-supported single and splinted crowns.

BACKGROUND: Studies assessing and comparing clinical and radiographic peri-implant status around narrow diameter implant-supported single crowns (NDISCs) and splinted crowns (NDISPs) are scarce. OBJECTIVE: The aim of this retrospective study was to estimate and compare complication rates, patient satisfaction, peri-implant status and peri-implant bone loss (PBL) of NDISCs and NDISPs. MATERIALS AND METHODS: Patients receiving narrow diameter implants (NDIs) in the posterior mandible were assessed. Technical complication and patient satisfaction were recorded. Clinical peri-implant plaque index (PI), bleeding on probing (BoP), probing depth (PD) and PBL were assessed. Technical complications and patient satisfaction were recorded. Log-rank test was computed to evaluate the influence of prostheses type and NDIs location on technical complications. P-value less than 0.05 was regarded as significant. RESULTS: Seventy-eight patients (43 male and 35 females) agreed to follow up. The mean follow-up duration of the patients was 3.6 years. A total of 102 (43 NDISCs and 59 NDISPs) NDIs with moderately rough surfaces were included. No significant differences in PI, BoP, or PD were observed between NDISCs and NDISPs. The average PBL score was 1.17 (range: 0.03-4.15) at implant level and 1.14 (range: 0.03-4.14) at patient level. Seven implants and three patients showed peri-implantitis. The rates of technical complication of single crowns were significantly higher than those of splinted crowns (P = 0.036). PBL was significantly higher in molar sites than those in premolar sites (P = 0.041). A total of 67 patients (85.9%) were satisfied with the esthetics of the crowns, while a total of 59 patients (75.6%) were satisfied with the function of the crowns. CONCLUSION: NDISCs and NDISPs offer high patient satisfaction and tolerable complication rates. Peri-implant conditions and peri-implant bone levels were comparable around NDISCs and NDISPs. However, bone loss of implants was higher in molar sites than those implants in premolar sites.

Comparative Effect of Different Polymerization Techniques on the Flexural and Surface Properties of Acrylic Denture Bases.

PURPOSE: Polymerization techniques have been modified to improve physical and mechanical properties of polymethylmethacrylate (PMMA) denture base, as have the laboratory procedures that facilitate denture construction techniques. The purpose of the present study was to investigate the effect of autoclave polymerization on flexural strength, elastic modulus, surface roughness, and the hardness of PMMA denture base resins. MATERIALS AND METHODS: Major Base and Vertex Implacryl heat-polymerized acrylic resins were used to fabricate 180 specimens. According to the polymerization technique, tested groups were divided into: group I (water-bath polymerization), group II (short autoclave polymerization cycle, 60°C for 30 minutes, then 130°C for 10 minutes), and group III (long autoclave polymerization cycle, 60°C for 30 minutes, then 130°C for 20 minutes). Each group was divided into two subgroups based on the materials used. Flexural strength and elastic modulus were determined by a three-point bending test. Surface roughness and hardness were evaluated with a profilometer and Vickers hardness (VH) test, respectively. One-way ANOVA and the Tukey-Kramer multiple-comparison test were used for results analysis, which were statistically significant at p ≤ 0.05. RESULTS: Autoclave polymerization showed a significant increase in flexural strength and hardness of the two resins (p < 0.05). The elastic modulus showed a significant increase in the major base resin, while a significant decrease was seen for Vertex Implacryl in all groups (p < 0.05); however, there was no significant difference in surface roughness between autoclave polymerization and water-bath polymerization (p > 0.05). CONCLUSION: Autoclave polymerization significantly increased the flexural properties and hardness of PMMA denture bases, while the surface roughness was within acceptable clinical limits. For a long autoclave polymerization cycle, it could be used as an alternative to water-bath polymerization.

Impact of Denture Cleansing Solution Immersion on Some Properties of Different Denture Base Materials: An In Vitro Study.

PURPOSE: To evaluate the effect of several denture cleansing solutions on the color stability, surface roughness, and flexural strength of three denture base materials. MATERIALS AND METHODS: Twenty-seven specimens were prepared using heat-polymerized (HP) denture base material, 27 using autopolymerized (AP) denture base material, and 27 using visible-light-polymerized (VLP) denture base, creating a total of 81 specimens. The specimens were randomly divided into three groups (n = 27): the distilled water group (DWG), Corega group (CG), and Renew group (RG). Color changes (ΔE), surface roughness (Ra, nm), and flexural strength (MPa) of each specimen were measured using a spectrophotometer, an optical profilometer, and a universal testing machine, respectively. The results were statistically analyzed using a one-way ANOVA and a post hoc Tukey's test (α = 0.05). RESULTS: The only statistically significant color change detected was in the VLP resin treated with Corega and Renew. There was a significant increase in the surface roughness of all denture resin groups after immersion in Corega. Immersion in Renew significantly increased surface roughness only in the HP and AP specimens. The only significant reduction in flexural strength was detected in the HP resin after immersion in Corega (p < 0.05). CONCLUSIONS: Within the limitations of this study, it can be concluded that Corega has a significantly greater negative impact than distilled water on the flexural strength of HP resin base materials. Renew significantly increased the surface roughness of AP and HP, while Corega increased the surface roughness of all resin materials.

Peri-implant soft tissue status and crestal bone levels around adjacent implants placed in cigarette smokers and never smokers: Five-year follow-up results.

BACKGROUND: It is hypothesized that peri-implant soft tissue inflammation and crestal bone loss (CBL) are higher around adjacent implants placed in cigarette smokers compared with never smokers. The aim of the present 5-years follow-up retrospective clinical study was to compare the peri-implant soft tissue status and CBL around adjacent implants placed in cigarette smokers and never smokers. METHODS: Cigarette smokers (group 1) and never smokers (group 2) with adjacent dental implants were included. Demographic information regarding age, sex, duration of smoking (pack-years), daily frequency of toothbrushing and most recent visit to a dentist or dental hygienist were recorded using a questionnaire. Information regarding implant dimensions (length × diameter), duration of implants in function, loading protocol (and type of restoration was recorded. Peri-implant plaque index (PI), bleeding on probing (BOP), probing depth (PD), and mesial and distal CBL were measured. P <0.05 were considered statistically significant. RESULTS: Seventy-two male participants (37 in group 1 and 35 in group 2) were included. The mean age of individuals in groups 1 and 2 were 50.3 ± 5.4 and 48.5 ± 3.8 years, respectively. In group 1, the mean duration of cigarette smoking was 22.3 ± 1.6 pack years. A family history of smoking was more often reported by individuals in group 1 compared with group 2. In groups 1 and 2, 54 and 70 adjacent implants, respectively were placed in the regions of missing premolars and molars. All implants were delayed loaded and were fixed with non-splinted screw-retained restorations. In groups 1 and 2, toothbrushing twice daily was reported by 78.3% and 74.2% individuals, respectively. There was no statistically significant difference in peri-implant PI, BOP, PD, and mesial and distal CBL among individuals in groups 1 and 2. CONCLUSION: Peri-implant soft tissue status and crestal bone levels were comparable around adjacent dental implants placed in cigarette smokers and never smokers.

Proinflammatory cytokine levels and peri-implant parameters among cigarette smokers, individuals vaping electronic cigarettes, and non-smokers.

BACKGROUND: Tobacco smoking compromises the prognosis of dental implant treatment and is associated with increased risk of peri-implant bone loss and increased implant failure rate. There is a dearth of studies that have compared clinical, radiographic, and immunological peri-implant parameters among cigarette smokers (CS), individuals vaping e-cigarettes (e-cigs), and non-smokers (NS). This study aimed to compare clinical and radiographic peri-implant parameters and levels of matrix metalloproteinase (MMP)-9 and interleukin (IL)-1ß levels among CS, individuals' vaping e-cigs, and NS. METHODS: Thirty-two CS (group 1), 31 individuals vaping e-cigs (group 2), and 32 NS (group 3) were included. Demographic- and implant-related data were collected using a structured baseline questionnaire. Peri-implant plaque index (PI), bleeding on probing (BOP), and probing depth (PD) were recorded and marginal bone loss (MBL) were assessed using standardized digital radiographs. Enzyme-linked immunosorbent assay was used to assess levels of MMP-9 and IL-1ß in peri-implant sulcular fluid. Pearson correlation coefficient was used to analyze for correlations of MMP-9 and IL-1ß levels with peri-implant parameters. RESULTS: BOP showed significantly higher values in group 3 as compared with groups 1 and 2 (P < 0.01). PI (P < 0.01), PD ≥ 4 mm (P < 0.01), and mean concentrations of MMP-9 (P < 0.001) and IL-1ß (P < 0.01) were significantly higher in groups 1 and 2 than group 3. MBL was significantly higher in group 1 as compared with group 2 and group 3 (P < 0.01). Significant positive correlations were found between MMP-9 (P = 0.0198) and IL-1ß (P = 0.0047) levels and MBL in group 1; and a significant positive correlation between IL-1ß and MBL in group 2 (P = 0.0031). CONCLUSIONS: Peri-implant health was compromised among CS than vaping individuals and NS. Increased levels of proinflammatory cytokines in CS and vaping individuals may suggest greater peri-implant inflammatory response.

Clinical performance of one-piece zirconia dental implants: A systematic review.

The aim of the present review was to evaluate the clinical and radiographic performance of one-piece zirconia implants (O-PZI). This review followed the PRISMA (Preferred Reporting Items for Systematic Review and Meta-Analysis) guidelines that addressed the following focused question: What is the overall clinical and radiographic performance of O-PZI? The MEDLINE, EMBASE, Cochrane Central Register of Controlled Trials, and Cochrane Oral Health Group Trials Register databases were searched. Six clinical studies were included. For studies evaluating O-PZI compared with one-piece titanium implants, zirconia implants showed higher crestal bone loss (CBL) in both the studies. However, one study demonstrated a high failure rate compared to titanium dental implants, while one study demonstrated comparable survival rates between zirconia and titanium dental implants. For studies evaluating O-PZI for the restoration of single crown and fixed dental prostheses, O-PZI showed comparable bone loss and survival rates for single crowns and fixed dental prostheses. Two studies were included that compared O-PZI with two-piece zirconia (T-PZI). One study showed a higher CBL and low survival rate for O-PZI compared to T-PZI, whereas the other study demonstrated comparable CBL and survival rates between O-PZI and T-PZI. It is still debatable whether O-PZI demonstrate better clinical performance when compared with titanium implants or two-piece design.

Evaluation of the Effect of Glow Discharge Plasma Surface Treatment on Bonding Cements to Zirconia.

BACKGROUND: The major difference in the chemical composition of Y-TZP ceramics, as compared with conventional porcelain, led researchers to develop alternative solutions for achieving durable and long term bonding with the zirconia surface. OBJECTIVE: The study aims to evaluate the effects of glow discharge treatment on the bonding between cement and zirconia. METHODS: The zirconia rings and rods were prepared with the Zirconia Y-TZP powder and TZ-3YSB-E (Tosoh-Zirconia) through auto-mix to investigate the glow discharge and thermo-cycling. An orientation Teflon mold was used to centralize each rod into the zirconia ring, and aided as a cementation jig during the cementation procedure. RESULTS: Cohesive failure (2/3 or more of luting agent remained on the zirconia surface) has been majorly observed with RelyX Ultimate, while adhesion failure (less than 1/3 of the luting agent remained on the zirconia surface) has been primarily observed in Ketac-Cem. Mixed failure was observed among the three specimen including Rely X Unicem 2, Multilink Auto-mix and Ceramir. CONCLUSION: The glow discharge surface treatment procedure had a major impact on bond strength to zirconia.

Peri-implant soft tissue status and crestal bone levels around adjacent implants placed in patients with and without type-2 diabetes mellitus: 6 years follow-up results.

BACKGROUND: The long-term success and survival of dental implants type-2 diabetic subjects is debatable. PURPOSE: The present 6 years' follow-up prospective clinical study compared the peri-implant soft tissue status and crestal bone loss (CBL) around adjacent implants placed among type-2 diabetic and nondiabetic subjects. MATERIALS AND METHODS: Type-2 diabetic (Group-1) and nondiabetic individuals (Group-2) with adjacent dental implants were included. Hemoglobin A1c (HbA1c) levels were recorded; and a questionnaire was used to collect demographic information. Information regarding implant dimensions, duration in function, loading protocol, and type of restoration was recorded. Peri-implant bleeding-on-probing (BOP), plaque index (PI), probing depth (PD), and mesial and distal CBL were measured. P < .05 were considered statistically significant. RESULTS: Eighty-six male participants (44 in Group-1 and 42 in Group-2) were included. The mean age of individuals in groups 1 and 2 were 57.6 ± 5.5 and 61.6 ± 4.3 years, respectively. In Group-1, the mean duration of type-2 diabetes was 10.1 ± 3.5 years. A family history of diabetes was more often reported by individuals in Group-1 than Group-2. In groups 1 and 2, 44 and 42 pairs of adjacent implants, respectively were placed in the regions of missing premolars and molars in both arches. All implants were delayed loaded and were fixed with non-splinted screw-retained restorations. In groups 1 and 2, tooth-brushing twice daily was reported by 79.5% and 85.7% individuals, respectively. There was no difference in peri-implant PI, BOP, PD, mesial and distal CBL and HbA1c levels among individuals in groups 1 and 2. CONCLUSION: Adjacent implants can remain esthetically and functionally stable in type 2 diabetic patients in a manner similar to healthy individuals provided glycemic levels are strictly controlled and maintained.

Effect of antimicrobial photodynamic therapy in open flap debridement in the treatment of peri-implantitis: A randomized controlled trial.

BACKGROUND: To evaluate the effects of single application of antimicrobial photodynamic therapy (aPDT) as an adjunct to open flap debridement (OFD) and OFD alone in patients with peri-implantitis (PI). MATERIALS AND METHODS: Twenty four patients with PI were divided into 2 groups receiving aPDT with OFD and OFD alone respectively. Peri-implant plaque index (PI), bleeding on probing (BOP), pocket depth (PD) and marginal bone level (MBL) were assessed at baseline, 6 and 12 months post-therapy. Digital periapical radiographs were taken and viewed on a calibrated computer screen using a software for the assessment of MBL. Only single implant from each patient was included in the study protocol (intent to treat analysis). RESULTS: At baseline, peri-implant PI, BOP, PD and MBL were comparable among individuals in aPDT and OFD groups. All patients had localized peri-implant PD ≥5 mm. At 6 months, aPDT and OFD significantly reduced peri-implant PI, BOP, PD and MBL. Similarly, after 12 months post-therapy, both groups reduced PI, BOP, PD and MBL. However, there was no significant difference between aPDT and OFD groups over time. CONCLUSION: Single application of aPDT as an adjunct to OFD does not provide additional benefit in improving clinical and radiographic peri-implant parameters in peri-implantitis.

Peri-implant parameters, tumor necrosis factor-alpha, and interleukin-1 beta levels in vaping individuals.

BACKGROUND: To the author's knowledge, there has been no study that has assessed clinical, radiographic, and immunological peri-implant parameters among individuals vaping e-cigarette (e-cig). PURPOSE: This pilot study aimed to compare clinical and radiographic peri-implant parameters and levels of tumor necrosis factor alpha (TNF-α) and interleukin (IL)-1ß levels among individuals vaping e-cigs and never smoker (NS). MATERIALS AND METHODS: Forty-seven individuals vaping e-cigs (group-1) and 45 NS (group-2) were included. Demographic and implant-related data were collected using a structured baseline questionnaire. Peri-implant plaque index (PI), bleeding on probing (BOP), and probing depth (PD) were recorded and peri-implant bone loss (PIBL) were assessed using standardized digital radiographs. Enzyme-linked immunosorbent assay was used to assess the levels of TNF-α and IL-1ß in peri-implant sulcular fluid. RESULTS: Bleeding on probing showed statistically significantly higher values in group-2 patients as compared to group-1 patients (P < .01). Probing depth ≥ 4 mm and PIBL was statistically significantly higher in group-1 patients as compared to group-2 patients (P < .05). Mean concentrations of TNF-α (P < .001) and IL-1ß (P < .01) were statistically significantly increased in individuals in group 1 as compared with group 2. A significant positive correlations were found between TNF-α levels and BOP (P = .024) and PIBL (P = .016); and significant positive correlation was found between IL-1ß and PIBL (P = .018) in group 1, respectively. CONCLUSIONS: Clinical and radiographic peri-implant parameters are compromised among vaping individuals. Increased levels of proinflammatory cytokines in peri-implant sulcular fluid may suggest greater local inflammatory response in vaping individuals for peri-implant inflammation.

Internal Fit and Marginal Gap Evaluation of Zirconia Copings Using Microcomputed Tomography: An In Vitro Analysis.

The purpose of this in vitro study was to measure the marginal and internal fit of single-unit all-ceramic zirconia copings (ZCs) fabricated through three different computer-aided design/computer-assisted manufacture (CAD/CAM) systems using microcomputed tomography (microCT). A total of 10 ZCs were produced for each experimental group. Scanning of the stainless steel (SS) model with its respective copings was conducted with a SkyScan machine. DataViewer software was used to acquire cross-sectional images. Locations of cross-sections for all specimens were standardized to reduce errors. Seven different cross-section locations were selected: four transverse and three sagittal. Adobe Photoshop CS3 was used for the measurements. One-way analysis of variance and Tukey post hoc test were used for the statistical analysis for each group. In addition, t test (α = .05) was used to compare values at each measurement location for the different groups. The results of this study show significant differences in the precision of fit of the experimental groups at the axio-occlusal transition (AOT) location, with a significant gap present in the DeguDent CAD/CAM System compared to the other two systems. Tukey test results indicate a significant difference in the marginal gap between the DeguDent CAD/CAM System and KaVo Everest Dental CAD/CAM System (P = .004). In addition, there is a significant difference in gap size values in the sagittal sections distal to the midline between the DeguDent CAD/CAM System and the Lava Ultimate CAD/CAM System (P = .002). The different CAD/CAM systems showed a clinically acceptable internal fit and marginal adaptation. Different levels of fit were found between the experimental groups. Marginal adaptation was the best in all experimental groups. The gap at the AOT area varied among the three groups, with the DeguDent CAD/CAM System showing the greatest value.

Effect of photodynamic and laser therapy in the treatment of peri-implant mucositis: A systematic review.

BACKGROUND: The present study systematically reviewed the literature to investigate the effect of photodynamic therapy (PDT) or laser therapy (LT) in the management of peri-implant mucositis (p-iM). METHODS: The electronic databases were searched until October 2017. Outcome measures were bleeding on probing (BOP), plaque index (PI), or probing depth (PD). The addressed PICO question was: "Is PDT and LT effective in the management of p-iM?" RESULTS: A total of five studies included in the qualitative analysis, two of which had a low risk of bias. Three studies used PDT while two studies used LT. All studies reported a significant improvement in clinical peri-implant inflammatory parameters in p-iM. For PDT, one study demonstrated a significant reduction for PDT group as compared to manual debridement (MD), while one study indicated comparable outcomes when tested with probiotics at follow-up. One study used PDT alone and indicated significant improvements in peri-implant parameters at follow-up. However, in the studies using LT, one study demonstrated a significant improvement in peri-implant parameters as compared to scaling and root planing alone, while other study indicated comparable outcomes when compared with manual debridement/chlorhexidine group at follow-up. CONCLUSION: This systematic review demonstrated inconclusive findings to show the effect of PDT or LT in the management of p-iM due to methodological heterogeneity such as non-standard control groups, laser parameters and short follow-up period. The results of this review should be considered preliminary and further, more robust, well-designed studies with long-term follow up and standardized comparators with laser parameters are warranted.

Frequency of Root Canal Treatment among Patients Attending a Teaching Dental Hospital in Dammam, Saudi Arabia.

OBJECTIVE: The purpose of the study was to evaluate the frequency and status of root canal-treated teeth in patients treated at the College of Dentistry, University of Dammam in the Eastern Province of Saudi Arabia. MATERIALS AND METHODS: A total of 3701 patients visited the clinics during the study period. Through the use of radiographs, 161 patients were initially selected who had endodontically treated teeth. However, after applying the inclusion criteria, the total number of eligible cases was reduced to 155. Patients were divided into three groups according to age (children 1-12 years, adults 13-65 years and geriatrics >65 years). RESULTS: On average, each patient had 2.28 ± 1.88 root canal-treated teeth and 24.02 ± 5.03 teeth without root canal treatment. The average number of endodontically treated teeth increased with an increase in age. The adult group showed the highest number of root-filled teeth 314 (93.4%). Of the 336 endodontically treated teeth, only 75 (22.3%) teeth exhibited periapical radiolucency. First molars (28.43-36.36%) and second premolars (20.1-27.27%) were the most frequently root-filled teeth in both jaws, followed by the first maxillary premolars (11.76%). Periapical lesions showed an almost similar pattern with the highest number of radiolucencies found in the first molars in both jaws (29.3-33.3%) followed by the second premolars in the mandible (30.6%) and first premolars in both jaws (20.8-25%). CONCLUSION: The first molars and second premolars were the most frequently root-filled teeth in both jaws, followed by maxillary first premolars. Periapical lesions showed an almost similar pattern among teeth with a higher number of radiolucencies found in the first molars in both jaws, followed by the second premolars in the mandible and the first premolars in both jaws.

Effect of Aging Regimens on Resin Nanoceramic Chairside CAD/CAM Material.

PURPOSE: To evaluate the effect of cyclic mechanical loading, thermal cycling, and storage in water on a resin nanoceramic chairside computer-aided designed/computer-aided manufactured (CAD/CAM) material compared to a control leucite-reinforced glass-ceramic material. MATERIALS AND METHODS: One hundred twenty specimens (18 × 4 × 3 mm) were milled from two chairside CAD/CAM materials' blocks (Lava Ultimate: LU; Vitablock Mark II: VM). Each group included four subgroups (A: n = 20 control; B: n = 20 cyclic loading [105 cycles, 80 N]; C: n = 20 thermal cycling [5 to 55°C]; D: n = 60 water storage [20: 3 months; 20: 6 months; 20: 9 months at 37°C]). Each subgroup included 10 specimens tested for flexure strength using three-point bending in a universal testing machine. The other 10 specimens were tested for surface roughness using an automated profiler followed by testing for surface hardness using a microhardness tester. RESULTS: LU displayed higher flexure strength than VM before and after all the aging conditions. The surface roughness for VM was lower than LU for the control, but both materials showed comparable values and significant increases after 9 months storage in water. After cyclic loading, only VM displayed a significant increase in the surface roughness value (p < 0.05). The surface hardness of VM was higher than LU for the control. VM did not show significant changes in hardness after any aging condition. LU showed significant reduction in surface hardness value only after storage in water (p < 0.05). CONCLUSION: The resin nanoceramic Lava Ultimate can be used as a durable substitute for glass-ceramic chairside CAD/CAM material.

Influence of incorporation of ZrO2 nanoparticles on the repair strength of polymethyl methacrylate denture bases.

BACKGROUND: Repeated fracture of the denture base is a common problem in prosthodontics, and it represents a nuisance and a time sink for the clinician. Therefore, the possibility of increasing repair strength using new reinforcement materials is of great interest to prosthodontists. AIM OF THE STUDY: This study aimed to evaluate the effects of incorporation of zirconia nanoparticles (nano-ZrO2) on the flexural strength and impact strength of repaired polymethyl methacrylate (PMMA) denture bases. MATERIALS AND METHODS: One hundred eighty specimens of heat-polymerized acrylic resin were fabricated (90 for each test) and divided into three main groups: one control group (intact specimens) and two groups divided according to surface design (45° bevels and butt joints), in which specimens were prepared in pairs to create 2.5 mm gaps. Nano-ZrO2 was added to repair resin in 2.5 wt%, 5 wt%, and 7.5 wt% concentrations of acrylic powder. A three-point bending test was used to measure flexural strength, and a Charpy-type test was used to measure impact strength. Scanning electron microscopy was used to analyze the fracture surfaces and nano-ZrO2 distribution. The results were analyzed with a paired sample t-test and an unpaired t-test, with a P-value of ≤0.05 being significant. RESULTS: Incorporation of nano-ZrO2 into the repair resin significantly increased flexural strength (P<0.05). The highest value was found in the bevel group reinforced with 7.5% nano-ZrO2, whereas the lowest value was found in the butt group reinforced with 2.5% nano-ZrO2. The impact strength values of all repaired groups were significantly lower than those of the control group (P<0.05). Among repaired groups, the higher impact strength value was seen in the butt group reinforced with 2.5% nano-ZrO2. The bevel joint demonstrated mainly cohesive failure, whereas the butt joint demonstrated mainly adhesive failure. CONCLUSION: Incorporation of nano-ZrO2 into the repair resin improved the flexural strength of repaired denture bases, whereas it decreased impact strength, especially with high nano-ZrO2 concentrations.

The Reinforcement Effect of Nano-Zirconia on the Transverse Strength of Repaired Acrylic Denture Base.

Objective. The aim of this study was to evaluate the effect of incorporation of glass fiber, zirconia, and nano-zirconia on the transverse strength of repaired denture base. Materials and Methods. Eighty specimens of heat polymerized acrylic resin were prepared and randomly divided into eight groups (n = 10): one intact group (control) and seven repaired groups. One group was repaired with autopolymerized resin while the other six groups were repaired using autopolymerized resin reinforced with 2 wt% or 5 wt% glass fiber, zirconia, or nano-zirconia particles. A three-point bending test was used to measure the transverse strength. The results were analyzed using SPSS and repeated measure ANOVA and post hoc least significance (LSD) test (P ≤ 0.05). Results. Among repaired groups it was found that autopolymerized resin reinforced with 2 or 5 wt% nano-zirconia showed the highest transverse strength (P ≤ 0.05). Repairs with autopolymerized acrylic resin reinforced with 5 wt% zirconia showed the lowest transverse strength value. There was no significant difference between the groups repaired with repair resin without reinforcement, 2 wt% zirconia, and glass fiber reinforced resin. Conclusion. Reinforcing of repair material with nano-zirconia may significantly improve the transverse strength of some fractured denture base polymers.

Real-time-guided bone regeneration around standardized critical size calvarial defects using bone marrow-derived mesenchymal stem cells and collagen membrane with and without using tricalcium phosphate: an in vivo micro-computed tomographic and histologic experiment in rats.

The aim of the present real time in vivo micro-computed tomography (µCT) and histologic experiment was to assess the efficacy of guided bone regeneration (GBR) around standardized calvarial critical size defects (CSD) using bone marrow-derived mesenchymal stem cells (BMSCs), and collagen membrane (CM) with and without tricalcium phosphate (TCP) graft material. In the calvaria of nine female Sprague-Dawley rats, full-thickness CSD (diameter 4.6 mm) were created under general anesthesia. Treatment-wise, rats were divided into three groups. In group 1, CSD was covered with a resorbable CM; in group 2, BMSCs were filled in CSD and covered with CM; and in group 3, TCP soaked in BMSCs was placed in CSD and covered with CM. All defects were closed using resorbable sutures. Bone volume and bone mineral density of newly formed bone (NFB) and remaining TCP particles and rate of new bone formation was determined at baseline, 2, 4, 6, and 10 weeks using in vivo µCT. At the 10th week, the rats were killed and calvarial segments were assessed histologically. The results showed that the hardness of NFB was similar to that of the native bone in groups 1 and 2 as compared to the NFB in group 3. Likewise, values for the modulus of elasticity were also significantly higher in group 3 compared to groups 1 and 2. This suggests that TCP when used in combination with BMSCs and without CM was unable to form bone of significant strength that could possibly provide mechanical "lock" between the natural bone and NFB. The use of BMSCs as adjuncts to conventional GBR initiated new bone formation as early as 2 weeks of treatment compared to when GBR is attempted without adjunct BMSC therapy.