Effect of a novel rotation coordinating device on registered horizontal condylar guidance of nonarcon semi-adjustable articulators.

Background: Horizontal condylar guidance (HCG) is registered by protrusive interocclusal records but in nonarcon articulators, these records can affect the accuracy. The present study aimed to evaluate the effect of a novel rotation coordinating device (RCD) on condylar guidance setting with protrusive interocclusal records. Materials and Methods: The study was designed as a comparative in-vitro investigation. Stone maxillary and mandibular casts were mounted on a fully adjustable instrument as the patient. Duplicate casts were mounted on an arcon and a nonarcon articulator with corresponding face bow records and in maximum intercuspation relation. Five different condylar guidance inclinations for both sides (20°, 30°, 40°, 50°, and 60°) were set on the fully adjustable instrument and 16 protrusive interocclusal records were established at each setting. HCG was set for arcon, nonarcon articulators, and nonarcon articulators with RCD. Data were analyzed using one-sample t-test to compare with actual HCG and one-way analysis of variance (α =0.05). Results: Mean HCG for studied articulators was 35.40 for arcon, 30.31 for nonarcon without RCD, and 35.61 for nonarcon with RCD which were significantly different from actual HCG (P < 0.05). HCG of the nonarcon with RCD showed no significant difference with arcon articulator (P = 0.71) while both were significantly different from nonarcon without RCD (P < 0.001). Conclusion: "The RCD" compensates the condylar guidance inclination difference between arcon and nonarcon articulators. The device precisely transfers the hinge movement of the upper member of the articulator to the condylar track.

Lithium metasilicate glass-ceramic fabrication using spark plasma sintering.

Background: The digital dentistry, requires materials with wo opposite properties of machining ability and also enough hardness. The main objective of this experimental study was to investigate the fabrication feasibility of the lithium metasilicate glass-ceramic in partially crystalized stated using the spark plasma sintering (SPS) method. Materials and Methods: In this study, SPS for the first time was used to fabricate primary lithium metasilicate glass-ceramic (LMGC) blocks. The raw materials were mixed and melted and then quenched in water and the resulted frits were grinded. The resulting powder was sintered by SPS at 660, 680, and 700°C. Results: Scanning Electron Microscope (SEM), X-ray diffraction (XRD), and Vicker's microhardness assay were used to evaluate the properties of samples. Statistical comparison of the obtained data was performed by ANOVA, followed by the post hoc test of Duncan. Microstructural studies by SEM and XRD showed that all samples were composed of lithium metasilicate phase in a glassy matrix. With increasing the sintering temperature, the number and size of lithium metasilicate particles increased and higher mechanical properties have been achieved. However, the sintered sample at 700°C has less processing ability than the samples sintered at 660 and 680°C. Conclusion: The optimum sintering temperature for glass frit consolidation was determined by SPS at 680°C.

Clinical performance of implant supported mandibular overdentures with cantilever bar and stud attachments: A retrospective study.

BACKGROUND: Treatment of edentulous patients with implant-supported over-dentures improves denture's retention and stability. Published data concerning implant-supported overdenture with cantilever bars that claimed that can affect the survival and bone loss of implants are scarce. PURPOSE: The purpose of this study was to evaluate 5-year clinical performance of mandibular implant-supported over-dentures with different attachment systems. MATERIALS AND METHODS: In this retrospective study, 103 patients who had received mandibular over-dentures supported by two implants were evaluated in a 5-year follow up. Studied groups were patients with Spherblock ball attachment (58 patients), Dolder bar with cantilever (36 patients), and Locator attachment (9 patients). Marginal bone-loss around implants, prosthetic complications, soft tissue status of the implants (gingival index, plaque index, pocket depth, and bleeding on probing) were used to compare studied groups. Visual Analogue Scale (VAS) criteria was used to assay patient's satisfaction. One-way ANOVA, Scheffe, Kruskal-Wallis, Mann-Whitney, and Fisher's exact tests, were used for the data analysis (α = 0.05). RESULTS: One hundred and three patients (46 male, 57 female, mean age 64.7 ± 8.6) with 206 implants (Strauman) were studied. The implant survival rate was 100% with mean bone loss of 0.22 mm around implants in 5 years. Prosthetic complications including attachment wear and denture fracture occurred more often with ball attachments. The number of attachment replacement, and post insertion appointments were significantly less in patients with bar attachments (p < 0.05). Pocket depth and gingival index were less in the ball attachment (p < 0.05). CONCLUSION: Mandibular overdenture supported by two implants can be considered a successful treatment in edentulous patients. The frequency of prosthetic complication is higher in unsplinted than splinted superstructures.

Comparing the color match of monolithic CAD-CAM dental ceramics with the VITA Classical shade guide.

STATEMENT OF PROBLEM: Matching the shade selected and the final color of a ceramic restoration is challenging, and studies on matching monolithic ceramics to the shade selected are lacking. PURPOSE: The purpose of this in vitro study was to compare the color match of monolithic lithium disilicate (LDS), zirconia-reinforced lithium silicate (ZLS), presintered zirconia-reinforced lithium silicate (PS-ZLS), polymer-infiltrated ceramic network (PICN), and multilayer zirconia with the 3 modes of the VITA Classical shade guide. MATERIAL AND METHODS: This study was performed on 50 rectangular plates (14×12×1 mm) of 5 types of ceramics with A2 shade (n=10). Zirconia specimens were evaluated in 3 locations: incisal, medial, and cervical thirds. The color coordinates of the specimens of all 7 groups were measured on #3 and #8 Ivoclar Natural Die Color material by using a reflective spectrophotometer. The color coordinates of A2 VITA shade were measured in 5 modes: without backing placed in specimen holder, shade tab on the backgrounds #3 and #8, and 1-mm-thick shade tab on the backgrounds #3 and #8. The color difference of each specimen with 3 modes of A2 shade (without backing and on similar backgrounds) was calculated by using the ΔE00 formula, and comparison among groups was performed by using 2-way ANOVA and Tamhane post hoc tests. The comparison of ΔE00 between the values obtained from backgrounds #3 and #8 was performed by using the independent t test (α=.05). RESULTS: In both backgrounds, statistically significant differences were found between the studied groups and VITA shade (P<.001). In most situations, the amount of color difference was lowest for the "shade tab on the backgrounds" mode. On background #3, the highest color difference was related to ZLS (6.48 ±0.23), and the lowest values were observed in the PICN group (1.02 ±0.31). On background #8, the highest color difference was related to ZLS compared with the "without backing" mode (8.62 ±0.27), and the lowest values were reported for ZLS compared with the "shade tab on the backgrounds" mode (1.27 ±0.44). The independent t test showed a statistically significant color difference on the 2 different backgrounds for all situations (P<.001). CONCLUSIONS: Color selection of monolithic ceramics with the VITA Classical shade guide is improved by placing the VITA tabs on a similar background. Background color has a significant effect on the final shade of the monolithic ceramics. Choosing the correct color for LDS, ZLS, and PS-ZLS requires more care than for PICN and zirconia.

Marginal Accuracy of Lithium Disilicate Full-Coverage Single Crowns Made by Direct and Indirect Digital or Conventional Workflows: A Systematic Review and Meta-Analysis.

PURPOSE: Several studies have compared digital intraoral scanners and conventional impressions. The accuracy of these two methods in terms of marginal accuracy of lithium disilicate crowns is not well-established, yet. The purpose of this study was to systematically review available publications on marginal fit of single-unit, full-coverage, tooth-supported lithium disilicate restorations. METHODS: Pubmed, Web of Science, Cochrane, EMBASE, and Scopus were electronically searched along with a manual search. After critical appraisal, data from selected studies were extracted and mean marginal difference with a 95% confidence interval was calculated. Meta-analysis of the collected data was conducted using STATA software. RESULTS: The meta-analysis revealed similar marginal gap values in intraoral scanners with conventional groups (p>0.05) and in intraoral scanners with extraoral canners (p>0.05). CONCLUSION: No significant difference was seen between digital and conventional impressions or intra- and extraoral scanners for marginal accuracy of lithium disilicate crowns.

Comparison of translucency and opalescence among different dental monolithic ceramics.

STATEMENT OF PROBLEM: Monolithic ceramic restorations designed by computer-aided design and computer-aided manufacturing are increasingly being used by clinicians. With the introduction of new materials, their optical characteristics also need to be investigated. PURPOSE: The purpose of this in vitro study was to compare the translucency and opalescence of lithium disilicate, zirconia-reinforced lithium silicate, presintered zirconia-reinforced lithium silicate, polymer-infiltrated ceramic-network material, and multilayer zirconia. MATERIAL AND METHODS: A total of 50 rectangular plates (14×12×1 mm) of 5 monolithic ceramics were prepared in this in vitro study (n=10). Each zirconia specimen was divided into 3 groups of incisal, middle, and gingival thirds. Each group was then evaluated separately. The color parameters of specimens were measured on 3 backgrounds, white, black, and #3 Ivoclar Natural Die Color material, by using a spectrophotometer. The translucency and opalescence of the specimens were determined by the relevant equations, and between-group comparisons were made. One-way ANOVA and Tamhane post hoc tests were used to compare groups (α=.05). RESULTS: The difference among the groups was significant in translucency (F=137.346, df=6, P<.001), contrast ratio (F=134.148, df=6, P<.001), and opalescence parameters (F=128.028, df=6, P<.001). The 3 zirconia groups (10.87 ±0.54 to 11.88 ±0.26) had a significantly lower translucency than the other groups, and the zirconia-reinforced lithium silicate group (18.14 ±0.74) showed the highest translucency. Zirconia-reinforced lithium silicate (12.36 ±0.42) had the highest opalescence, and the lowest opalescence was found for polymer-infiltrated ceramic-network (5.43 ±0.28) and the incisal third of zirconia (5.45 ±1.06). CONCLUSIONS: The zirconia-reinforced lithium silicate and presintered zirconia-reinforced lithium silicate specimens had the highest translucency and opalescence. The studied multilayer zirconia, which had different cubic phase values from incisal to gingival blank, showed similar translucency over the entire range, and differences among different regions were related to chromatic variables.

How the initial retentive force of implant-supported overdentures can be affected with splinted and unsplinted attachments systems.

Background: The aim of this study was to evaluate the retention of implant-supported overdentures with different attachment systems. Materials and Methods: In this in vitro study edentulous model with 2 Straumann implant in symphyseal region was used to make an overdenture with different attachment systems. (Dolder bar with 1 and 3 metal clips, Hader bar with 1 and 3 plastic clips, ball on bar with 2 and 4 plastic caps, Locator, Rhein plastic caps and Eleptical matrix). Retention values were recorded by universal testing machine with a cross speed of 50.8 mm/min in vertical, posteroanterior, and lateral direction. Repeated measure ANOVA and Duncan tests were used for the data analysis (α =0.05). Results: There was a statistically significant difference between the retention values of studied attachments in different dislodgment directions (P < 0.05). The highest and lowest retention were recorded for 4 balls on bar (56.71 N) and Rhein pink caps (27.89 N) in the vertical direction. Three metal clips (61.43 N) and Rhein pink cap (24.77 had the highest and lowest retention force in the posteroanterior direction. In the lateral direction, 4 balls on bar (62.68 N) and 1 plastic clip (32.27 N) showed the highest and lowest retention, respectively. Conclusion: If the higher retention force has been considered for implant-supported overdenture attachment selection, the clinician can use splinted bar or ball on bar superstructure.

Marginal adaptation of zirconia complete-coverage fixed dental restorations made from digital scans or conventional impressions: A systematic review and meta-analysis.

STATEMENT OF PROBLEM: Intraoral scanners have been increasingly used in recent years. However, the accuracy of digital scans as it affects marginal adaptation is unclear. PURPOSE: The purpose of this systematic review and meta-analysis was to compare the marginal adaptation of single-unit zirconia crowns fabricated with digital scans or with conventional impressions. MATERIAL AND METHODS: The electronic databases PubMed (MEDLINE), Cochrane Central Register of Controlled Trials (CENTRAL), Web of Science (ISI), Scopus, and EMBASE were searched and complemented by a manual search. Risks of bias were assessed by using a modified methodological index for nonrandomized studies (MINORS). Mean ±standard deviation (SD) values of marginal accuracy of studies were extracted for both methods. Mean marginal difference and 95% confidence interval (CI) were calculated to evaluate the marginal accuracy of each method. Pooled data were statistically analyzed by using a random-effect model. RESULTS: Seventeen studies were used to perform the meta-analysis. Subgroup analysis was performed based on intraoral scanners. Standardized mean marginal difference and 95% CI of each subgroup were as follows: Lava: -0.85 µm (95% CI: -1.67, -0.03) (P=.043); CEREC: -1.32 µm (95% CI: -2.06, -0.59) (P<.001); iTero: -0.44 µm (95% CI: -1.35, 0.47) (P=.338); TRIOS: -1.26 µm (95% CI: -2.02, -0.51) (P=.001); unknown scanner: -0.21 µm (95% CI: -1.14, 0.72); all studies: -0.89 µm (95% CI: -1.24, -0.54) (P<.001). CONCLUSIONS: Digital scanning of prepared teeth for single-unit zirconia restorations resulted in better marginal accuracy than conventional techniques using elastomeric impression materials.

Five year clinical outcomes of metal ceramic and zirconia-based implant-supported dental prostheses: A retrospective study.

OBJECTIVES: The implant-supported restorations can be made of all-ceramic materials. The purpose of this study was to compare five year clinical outcomes of zirconia-based and metal ceramic implant-supported fixed dental prostheses (FDPs). METHODS: In this study, 114 posterior implant-supported FDPs including zirconia-based (52) or metal ceramic (62) restorations were made for 114 patients with a mean age of 59 ±â€¯8.4 years and evaluated in a 5 year follow up. The modified California Dental Association (CDA) guidelines were used to assess the quality of the restorations. The soft tissue status was evaluated using gingival and plaque indices, probing depth and bleeding on probing. Additionally, the bone loss around implants was assessed by parallel priapical radiographs. The visual analogue scale was used regarding patients' satisfaction. The data analysis were performed by Kaplan-Meier, log rank test, Cox regression, Mann-Whitney U and Student's t-test. (α = 0.05). RESULTS: Five year Kaplan-Meier survival rate of the zirconia-based and metal ceramic FDPs were 98.1 % and 100 % respectively with no significant difference (P = 0.12). The success rates were 81.6 % for zirconia-based and 81.0 % for metal ceramic restorations (P = 0.85). The CDA rating of both studied groups was not significantly different except the marginal gap which was better in zirconia-based FDPs (P < 0.001). Fracture of veneering ceramics occurred in 2.7 % of metal ceramic and 6.4 % of zirconia-based FDPs, which were not considered as failure. Soft tissue status was not affected by the type of restorations except for plaque index which was more favorable for zirconia-based FDPs (P < 0.001). No significant difference was found between marginal bone loss of the two groups (P = 0.30 mesial, P = 0.46 distal). CONCLUSIONS: Zirconia-based and metal ceramic FDPs showed similar promising clinical performance in the 5-year follow-up. CLINICAL SIGNIFICANCE: Zirconia-based implant-supported FDPs might be a successful restorative method with acceptable survival rate and patient's satisfaction.

Biodegradable Magnesium Bone Implants Coated with a Novel Bioceramic Nanocomposite.

Magnesium (Mg) alloys are being investigated as a biodegradable metallic biomaterial because of their mechanical property profile, which is similar to the human bone. However, implants based on Mg alloys are corroded quickly in the body before the bone fracture is fully healed. Therefore, we aimed to reduce the corrosion rate of Mg using a double protective layer. We used a magnesium-aluminum-zinc alloy (AZ91) and treated its surface with micro-arc oxidation (MAO) technique to first form an intermediate layer. Next, a bioceramic nanocomposite composed of diopside, bredigite, and fluoridated hydroxyapatite (FHA) was coated on the surface of MAO treated AZ91 using the electrophoretic deposition (EPD) technique. Our in vivo results showed a significant enhancement in the bioactivity of the nanocomposite coated AZ91 implant compared to the uncoated control implant. Implantation of the uncoated AZ91 caused a significant release of hydrogen bubbles around the implant, which was reduced when the nanocomposite coated implants were used. Using histology, this reduction in the corrosion rate of the coated implants resulted in an improved new bone formation and reduced inflammation in the interface of the implants and the surrounding tissue. Hence, our strategy using a MAO/EPD of a bioceramic nanocomposite coating (i.e., diopside-bredigite-FHA) can significantly reduce the corrosion rate and improve the bioactivity of the biodegradable AZ91 Mg implant.

Effect of repeated firing on the translucency of CAD-CAM monolithic glass-ceramics.

STATEMENT OF PROBLEM: The effects of multiple firings on the translucency of newly introduced computer-aided design and computer-aided manufacturing (CAD-CAM) glass-ceramics have not been well evaluated. PURPOSE: The purpose of this in vitro study was to assess the changes in the translucency of high-translucency (HT) and low-translucency (LT) lithium disilicate (LDS) and zirconia-reinforced lithium silicate (ZLS) glass-ceramics of 0.6 and 1 mm thickness during crystallization, correction, and glaze firing cycles. MATERIAL AND METHODS: Eighty specimens in 8 groups (n=10) were sectioned and polished to obtain thicknesses of 0.6 and 1 mm. The specimens were then fired in 3 cycles, and the color coordinates were measured by using a spectrophotometer after each cycle. The translucency parameter (TP) and the contrast ratio (CR) were calculated to determine the translucency level. The data were analyzed by using a statistical software program. The TP and CR data after each firing cycle were compared within each group by using repeated-measures ANOVA. Pair-wise comparisons were made by using a multiple paired t test. Comparisons between the 2 thicknesses of different materials were made by using the independent t test (α=.05). RESULTS: Repeated firings significantly increased the translucency of 0.6-mm LT-LDS and decreased the translucency of 0.6-mm HT-ZLS (P<.017). No significant changes were noted in the translucency of specimens of 1-mm thickness after repeated firings. Also, 0.6-mm-thick specimens of all materials had significantly higher translucency than 1-mm-thick specimens (P≤.001). The highest translucency was noted in HT-LDS, followed by HT-ZLS. CONCLUSIONS: Repeated firings significantly affected the translucency of LDS and ZLS CAD-CAM glass-ceramics. The translucency increased with decreasing thickness.

The effect of the nano- bioglass reinforcement on magnesium based composite.

Nano-bioceramic particles serving as a reinforcement can improve the mechanical and biological properties of magnesium implants, but they might have some side effects, that must be addressed. In this research, magnesium composites including 10 wt% nano-bioglass (nBG) were fabricated using powder metallurgy (PM10) and spark plasma sintering (SPS10) methods for bone reconstruction purposes. The results of the compression test indicated that the SPS10 sample had higher mechanical properties, in comparison to the PM10 sample, and nBG had more reinforcing effect on the mechanical properties of magnesium matrix. X-ray difractometery indicated that nBG was chemically reacted with magnesium in the PM10 sample, and resulted in some extra phases (MgO and Mg2Si) formation, while there was no detectable extra phases in the SPS10 sample. However, a higher in vitro degradation rate was observed for PM10 sample, because of multi-phase formation at the magnesium matrix. To inhibit the chemical reaction between magnesium and nBG kinetically, a short time sintering process can be, therefore, recommended.

Improvement of in vitro behavior of an Mg alloy using a nanostructured composite bioceramic coating.

Magnesium (Mg) alloys as a new group of biodegradable metal implants are being extensively investigated as a promising selection for biomaterials applications due to their apt mechanical and biological performance. However, as a foremost drawback of Mg alloys, the high degradation in body fluid prevents its clinical applications. In this work, a bioceramic composite coating is developed composed of diopside, bredigite, and fluoridated hydroxyapatite on the AZ91 Mg alloy in order to moderate the degradation rate, while improving its bioactivity, cell compatibility, and mechanical integrity. Microstructural studies were performed using a transmission electron microscope (TEM), scanning electron microscope (SEM), X-ray diffraction (XRD) analysis, and energy dispersive spectroscopy (EDS). The degradation properties of samples were carried out under two steps, including electrochemical corrosion test and immersion test in simulated body fluid (SBF). Additionally, compression test was performed to evaluate the mechanical integrity of the specimens. L-929 fibroblast cells were cultured on the samples to determine the cell compatibility of the samples, including the cell viability and attachment. The degradation results suggest that the composite coating decreases the degradation and improves the bioactivity of AZ91 Mg alloy substrate. No considerable deterioration in the compression strength was observed for the coated samples compared to the uncoated sample after 4 weeks immersion. Cytotoxicity test indicated that the coatings improve the cell compatibility of AZ91 alloy for L-929 cells.

Five year clinical outcomes and survival of chairside CAD/CAM ceramic laminate veneers - a retrospective study.

PURPOSE: The aim of this clinical study was to compare the survival, modified California Dental Association (CDA) criteria, and periodontal parameters of laminate veneers made with Empress CAD and emax CAD over 60 months. METHODS: One hundred and ninety seven ceramic laminate veneers were placed in 71 patients in a private practice. The restorations were made using CEREC AC Bluecam with Empress CAD and emax CAD blocks. Modified CDA guidelines were used to evaluate clinical performance of the restorations. Gingival and plaque indices, probing pocket depth, and bleeding on probing were also recorded. Patient's satisfaction was assessed using visual analogue scale. Kaplan-Meier and Log rank test were used to analyze survival probability and success rate of the restorations. CDA rating of Empress CAD and emax CAD was compared with Log rank test (α=0.05). RESULTS: The survival rates of ceramic Empress CAD and emax CAD laminate veneers were 97.8 % and 100 % respectively (p=0.13). The success rate of these veneers was 92.4 % for Empress CAD and 100 % for emax CAD (p<0.05). Two Empress CAD laminate veneer failed because of fracture. Other restorations had very good or good CDA scores after 5 years. The periodontal parameters were not significantly different between first and fifth years except plaque index. The mean score of patients' satisfaction was 95.5±8.4. CONCLUSIONS: Chair-side computer-aided design/computer-aided manufacturing ceramic laminate veneers were clinically successful restorations with mean survival rate of 99.0 % and success rate of 96.4 % after 5 years.

Prevention of Cross-contamination Risk by Disinfection of Irreversible Hydrocolloid Impression Materials with Ozonated Water.

BACKGROUND: Disinfection of dental impression is mandatory for preventing the cross infection between dental staff and dental laboratory. Ozone as a disinfectant can be used in various ways in dentistry. The aim of this study was to evaluate the efficacy of ozonated water for disinfection of irreversible hydrocolloid impression materials and preventing cross-contamination. METHODS: Thirty-two circular specimens (1 cm diameter and 2 mm thickness) of irreversible hydrocolloid impression material were made. Thirty specimens were contaminated with Pseudomonas aeruginosa (ATCC 27853), Staphylococcus aureus (ATCC 51299), and Candida albicans (PTCC 5027). Except control samples (n = 2), the other specimens were immersed in ozonated water for 5 and 10 min (5 sample each group). Trypsin was used for separating microorganisms. Diluted microbial solution was analyzed microbiologically for colony-forming units (CFUs). Two-way repeated measure ANOVA and Scheffe post hoc test were used for data analysis (α = 0.05). RESULTS: The number of CFUs after disinfection with ozonated water was decreased significantly (11.84%, 61.55%, and 20.27% after 5 min and 11.03%, 14.50%, and 16.99% after 10 min for P. aeruginosa, S. aureus, and C. albicans, respectively) (P < 0.001). Increasing the time of disinfection resulted in significant reduction in a number of S. aureus only (P < 0.001) although they did not vanish microorganisms completely. CONCLUSIONS: Immersion of irreversible hydrocolloid impression material in ozonated water for 10 min will not lead to complete disinfection but decreases the microorganisms to a level that can prevent infection transmission.

Effect of cleaning methods on retentive values of saliva-contaminated implant-supported zirconia copings.

OBJECTIVE: The aim of this study was to evaluate the effect of different cleaning regimens on retentive strength of saliva-contaminated implant-supported zirconia copings. MATERIAL AND METHODS: Seventy solid titanium abutments with 5.5 mm height (Straumann) were attached to the regular neck implant analogs (Straumann). The abutment-analog complex was mounted vertically in an autopolymerized T-shaped acrylic resin block. Seventy zirconia copings with an occlusal loop were made. The copings were contaminated with fresh human saliva for 1 min (except the control group). Afterward, the specimens were washed with water spray for 15 s and dried for 15 s. The copings were divided into seven groups according to cleaning methods (n = 10). Group 1: no contamination (control group); Group 2: water spray rinsing; Group 3: airborne particle abrasion; Group 4: immersion in 96% isopropanol; Group 5: applying Ivoclean (Ivoclar Vivadent); Group 6: applying 1% sodium hypochlorite; and Group 7: applying Monobond Plus (Ivoclar Vivadent). The copings were luted with a resin luting agent (RelyX Unicem; 3M ESPE). After 5,000 thermal cycles, the retentive values of the restorations were tested using universal testing machine. The dislodging forces were analyzed using one-way analysis of variance and the Tukey's HSD tests (α = 0.05). RESULTS: The copings, which were cleaned with Ivoclean and 96% isopropanol, showed the highest retentive values (204.79 ± 44.49 and 232.65 ± 71.36, respectively). There was a significant difference between the studied groups (F = 2.735; p = .02). Tukey's HSD showed that there was no significant difference between the different cleaning procedures and control group except water rinsing group (p = .14). The lowest retentive value was related to the saliva-contaminated group, which were only cleaned with water rinsing method. CONCLUSION: The retentive values of zirconia-based restorations were adversely affected by saliva contaminations. These restorations can be cleaned by Ivoclean, 96% isopropanol, airborne particle abrasion, 1% sodium hypochlorite, or applying Monobond Plus before luting procedures.

The evaluation of prepared microgroove pattern by femtosecond laser on alumina-zirconia nano-composite for endosseous dental implant application.

Ceramic dental materials, especially alumina (20 %vol)-yttrium stabilized tetragonal zirconia poly crystal (A-Y-TZP20), have been considered as alternatives to metals for endosseous dental implant application. For increasing the bone-to-implant contact as well as the speed of bone formation, a new surface modification can be effective. The aim of this study was to design microgroove patterns by femtosecond laser on A-Y-TZP20 nano-composite disks for endosseous dental implant application. The phase composition and the morphology of the A-Y-TZP20 nano-composite samples were characterized using X-ray diffraction and Scanning electron microscopy equipped with energy dispersive X-ray spectroscopy techniques. Statistical analysis was submitted to Kolmogorov-Smirnov test and Student's t test for independent variables, with a 5 % significance level. EDAX analysis revealed a significant decrease in the relative content of contaminants like carbon (p < 0.05) in laser surface-treated group as compared to non surface-treated group. X-ray diffraction did not show any change in the crystalline structure induced by laser processing. It was concluded that the femtosecond laser is a clean and safe method for surface modification of A-Y-TZP20.

Relationship between Tooth Loss, Functional Dyspepsia and Gastro-Esophageal Reflux Disorder among Isfahani Adults.

BACKGROUND: Few studies have assessed the relationship between tooth loss and upper gastro-intestinal (GI) disorders including functional dyspepsia (FD) and gastro-esophageal reflux disease (GERD). This study aimed to investigate the relation between dental status and FD, its components and GERD among a large group of Isfahani adults. METHODS: In a cross-sectional study from April to May 2010, the dental status of 4109 Isfahani adults was evaluated using a self-administered questionnaire. Participants were categorized into three main groups: those with full dentition, individual who had lost 1-5 teeth and those who had lost >5 teeth. FD, its components and GERD were defined using Rome III criteria. Multivariable logistic regression was used to examine the relationship between dental status and gastrointestinal disorders. RESULTS: After adjustment for potential confounders, we found no significant association between dental status, FD and GERD. However, individuals who had lost 1-5 teeth and >5 teeth had 34% and 109% greater odds for early satiation, respectively. In addition, individuals who had lost 1-5 teeth were 24% likely to have postprandial fullness and epigastric pain. Stratified analyses by gender also revealed a significant association between dental status and GERD as well as FD in females; such that those who had lost 1-5 teeth had 33% greater chance for GERD and those who had lost >5 teeth were 101% more likely to have FD compared with those with full dentition. CONCLUSION: We found significant positive associations between tooth loss, GERD and FD in women, but not in men. We also found significant relations between tooth loss and components of FD, especially early satiety in the entire population.

Comparison of Marginal and Internal Adaptation of CAD/CAM and Conventional Cement Retained Implant-Supported Single Crowns.

PURPOSE: To evaluate the accuracy of marginal and internal adaptation of 2 computer-aided design/computer-aided manufacturing (CAD/CAM) and 2 conventionally made cement retained implant-supported restorations. MATERIALS AND METHODS: An abutment and its corresponding fixture analog (Astra Tech) were inserted in left central incisor area of a maxillary cast. Four types of implant-supported single restorations were fabricated on the abutment (n = 10): e.max CAD (Cerec AC system), zirconia-based (Cercon system), IPS e.max Press, and metal-ceramic restorations. The internal and marginal gaps of the studied groups were measured by replica method and stereomicroscope. Data were subjected to 1-way ANOVA and Scheffe post hoc tests (α = 0.05). RESULTS: Mean internal gaps of Cercon (59.48 ± 16.49 µm) and e.max Press (75.62 ± 26.92 µm) groups were significantly different from e.max CAD (120.29 ± 16.74 µm) group, but there was no significant difference between metal-ceramic restorations (89.65 ± 47.84 µm) and e.max CAD. The marginal gaps of e.max CAD (32.02 ± 10.38 µm) and Cercon restorations (34.26 ± 11.41 µm) were significantly superior from metal ceramics (59.19 ± 17.81 µm) and e.max press (74.99 ± 24.51 µm). CONCLUSION: Within the limitations of this study, it can be concluded that although the marginal and internal gaps of the studied implant-supported restorations were in the clinically acceptable range, single crowns made with CAD/CAM technology provide better marginal fit.

Clinical outcomes of zirconia-based implant- and tooth-supported single crowns.

OBJECTIVES: Zirconia-based restorations have been increasingly used on implant and teeth abutments, but the evidence about clinical outcomes of these restorations is limited. The aim of this study was to assess up to 7-year clinical outcomes of implant- and tooth-supported zirconia-based single crowns. MATERIALS AND METHODS: In this retrospective study, 261 patients with 556 single crowns supported by either teeth (324) or implants (232) were examined during 3- to 7-year follow-up (mean observation of 60.70 months for tooth and 59.20 months for implant-supported crowns). California Dental Association (CDA) quality evaluation system was used to evaluate the restorations. Soft tissue status was assessed using plaque and gingival index scores, bleeding on probing, and pocket depth. Patient and professional satisfaction were evaluated by visual analog scale (VAS). RESULTS: The 5-year Kaplan-Meier survival probability was 98.3 and 97.3 for implant- and tooth-supported crowns, respectively. In regard to CDA rating, most of the crowns were ranked as either excellent or acceptable (99.5 %). The recorded failures were replacement of the crown due to porcelain chipping (3), implant failure (1), and teeth extraction (5). Soft tissue parameters were not affected by the restorations compare to control teeth. The VAS was high for both patients and clinicians. CONCLUSIONS: Zirconia-based single crowns on both tooth and implant abutments showed promising clinical performance in this up to 7-year follow-up. CLINICAL RELEVANCE: The zirconia-based single crowns can be used clinically for tooth- and implant-supported restorations.