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.

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.

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.

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.

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.

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.

Effect of the processing cycle on dimensional changes of heat-polymerized denture base resins.

BACKGROUND: The second processing cycle for adding the artificial teeth to heat-polymerized acrylic resin denture bases may result in dimensional changes of the denture bases. The aim of this study was to evaluate the dimensional changes of the heat-polymerized acrylic resin denture bases with one and two-cycle processing methods. MATERIALS AND METHODS: A metal edentulous maxillary arch was used for making 40 stone casts. Maxillary complete dentures were made with heat-polymerized acrylic resins (Meliodent and Acropars) with one and two stage processing methods (n = 10 for each group). Linear dimensional changes in anteroposterior and mediolateral distances and vertical changes in the first molar region were measured following each processing cycle, using a digital caliper. Mean percentage of the dimensional changes were subjected to two-way analysis of variance and Tukey honest significant difference tests (α = 0.05). RESULTS: Postpolymerization contraction occurred in both anteroposterior and mediolateral directions in all studied groups; however, the vertical dimension was increased. Acropars acrylic resin showed the highest dimensional changes and the second processing cycle significantly affected the measured distances (P < 0.05). Meliodent acrylic resin was not significantly influenced by the processing method. CONCLUSION: Reheating of the acrylic resin denture bases for the addition of denture teeth result in linear dimensional changes, which can be clinically significant based on the acrylic resin used.

Retentive strength of implant-supported base metal copings over short metal abutments using different luting agents and surface treatments.

PURPOSE: To evaluate the effect of surface treatments on retention of implant-supported restorations over short abutments. MATERIALS AND METHODS: One hundred twenty metal copings were made on Straumann solid abutments (3 mm length). The copings were divided into 2 groups: control and air abraded (50 µm Al2O3). The copings were luted using Fleck's, Poly F, Panavia F, and Fuji Plus. In resin cements groups, 2 subgroups were studied base on the application of Alloy Primer (n = 10). After conditioning in saliva and 5000 thermal cycles, retentive strengths of specimens were measured. Data were analyzed by 1-way ANOVA and Tukey honestly significant difference tests (α = 0.05). RESULTS: Panavia F 2.0 combined with Alloy Primer showed the most retentive values. In control and air abraded groups, there was no significant difference between the studied luting agents. Alloy Primer significantly increased the retention of copings luted with Panavia F 2.0. CONCLUSION: Within the limitations of this study, the retentive strength of metal copings over short implant abutments was not improved by airborne-particle abrasion. However, Alloy primer enhanced the retention of metal copings that were luted using Panavia F 2.0.

Evaluation of hardness and wear resistance of interim restorative materials.

BACKGROUND: The interim restorative materials should have certain mechanical properties to withstand in oral cavity. The aim of this study was to evaluate the hardness and wear resistance of interim restorative materials. MATERIALS AND METHODS: Fifteen identical rectangular shape specimens with dimensions of 2 mm × 10 mm × 30 mm were made from 7 interim materials (TempSpan, Protemp 3 Garant, Revotek, Unifast LC, Tempron, Duralay, and Acropars). The Vickers hardness and abrasive wear of specimens were tested in dry conditions and after 1 week storage in artificial saliva. The depth of wear was measured using surface roughness inspection device. Data were subjected to Kruskal-Wallis and Mann-Whitney tests. The Pearson correlation coefficient was used to determine the relationship between hardness and wear (α =0.05). RESULTS: TempSpan had the highest hardness. The wear resistance of TempSpan (in dry condition) and Revotek (after conditioning in artificial saliva) was significantly higher (P < 0.05). There was no statistically significant correlation between degree of wear and hardness of the materials (P = 0.281, r = -0.31). CONCLUSION: Hardness and wear resistance of interim resins are material related rather than category specified.

Retentiveness of implant-supported metal copings using different luting agents.

BACKGROUND: With regard to potential retrievability of cement-retained implant restorations, the retentive strength of the luting agents is critical. The aim of this study was to evaluate the retention values of implant-supported metal copings using different luting agents. MATERIALS AND METHODS: Twenty ITI implant analogs and solid abutments of 5.5-mm height were embedded vertically in autopolymerizing acrylic resin blocks. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III). The copings were luted using eight cements with different retention mechanisms (Panavia F2.0, Fuji Plus, Fleck's, Poly F, Fuji I, Temp Bond, GC-free eugenol, and TempSpan) under static load of 5 kg (n=10). All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days and thermocycled for 5000 cycles (5-55°C). The dislodging force was measured using a universal testing machine at a crosshead speed of 5 mm/min. Statistical analyses were performed using Kruskal-Wallis (α=0.05) and Mann-Whitney tests with Bonferroni correction (α=0.001). RESULTS: Fuji Plus and TempSpan had the highest and the least mean retentive strength, respectively (320.97±161.47, 3.39±2.33). There was no significant difference between Fuji Plus, Fleck's, Ploy F, and Panavia F2.0. These cements were superior to provisional cements and Fuji I (P<0.001) which showed statistically same retentive strength. CONCLUSION: Within the conditions of this study, the resin modified glass ionomer, zinc phosphate, zinc polycarboxylate, and Panavia F2.0 had statistically the same retentive quality and are recommended for definitive cementation of single implant-supported restorations. The provisional cements and glass ionomer may allow retrievability of these restorations.

Association between food intake and oral health in elderly: SEPAHAN systematic review no. 8.

Dental status may influence food intake. The aim of this review was to summarize the earlier investigations on the association between food intake and dental status. We searched the electronic databases of PubMed and the Cochrane library for articles published until 30 February, 2012. To reach the related published articles, Medical Subject Heading (MeSH) terms of 'oral health,' 'masticatory performance,' 'dental status,' and 'eating' or 'food intake' were used. We included all research articles in the English language that (1) had used the random sampling method, and (2) had investigated the association between dental status and nutrient intake in elderly, non-denture wearer individuals, with no systemic illness. The findings of the seven original research articles had a great variation. Four of them supported a strong association between dietary intake and dental status and three of them found that there was no association between these variables. Most investigations found a significant relationship between the oral health status and nutrient intake; however, longitudinal studies were required for a better understanding of the diet-oral health relations.

Gastroesophageal reflux disease and tooth erosion: SEPAHAN systematic review no. 10.

Many systemic diseases affect oral health. The aim of this research was to conduct a systematic review on the association between dental erosion (DE) and gastroesophageal reflux disease (GERD) and the effect of saliva's flow rate, buffering capacity and oral microbial changes caused by GERD. All descriptive, analytical studies up to December 2011 that have relevant objectives, proper sampling method and sufficient results were included by searching PubMed and Scopus electronic data bases. Fifteen studies were selected according to our inclusion criteria (10 in adult and 5 in children population). There was a strong association between DE and GERD in the adult population, and the relationship in the children population was found to be of less importance. Early diagnosis and treatment of refluxed acid in both age groups through lifestyle changes and medications can prevent further damage and tooth loss.