The International Journal of Prosthodontics, 03/2022

Purpose: To evaluate the success of monolithic endocrowns fabricated using a digital workflow. Materials and Methods: Twenty-three patients requiring restoration of devitalized molars or premolars were included in the study. The preparation was scanned using an intraoral scanner (Cerec Bluecam, Dentsply Sirona), and a monolithic restoration was made from a nanoparticle resin-based hybrid composite (#10 Cerasmart [CS]; #10 Lava Ultimate [LU], 3M Espe) or a polymer-infiltrated ceramic (#10 Vita Enamic [VE]). At the time of placement and after 6 months, 1 year, and 5 years of function, radiographs were taken to evaluate the marginal integrity of the restorations, and clinical pictures were taken to assess the quality of the restoration using the USPHS criteria. Results: After 5 years, the restorative success rate was 70.8%, the restorative survival rate was 87.5%, and the tooth survival was 91.6%. Four chippings (two LU, two CS), three fractures (three LU), and two debonding of the restorations (two CS) occurred. Also, two teeth were extracted after 5 years of followup (two VE) because of secondary caries and a root fracture. The USPHS ratings were high, except for color match, which was rated the lowest at all time intervals. Conclusion: Nanoceramic endocrowns made using a completely digital workflow have an acceptable survival rate after 5 years. However, the complication rate was high.

Purpose: To retrospectively compare the incidence of biologic and prosthetic complications in implantsupported fixed dental prostheses (FDP) and removable dental prostheses (RDP) in edentulous patients after up to 10 years. Materials and Methods: A total of 13 patients (mean age: 58.8 years, women = 9, men = 4) who had received 14 implant-supported FDPs and a total of 43 patients (mean age: 64.4 years, 22 women, 21 men) who were provided with 50 implant-supported RDPs were included in the study. The RDPs were fixed using locator attachments, ball heads, bars, or double-crowns. Technical, biologic, and prosthetic complications were assessed over a 73.3-month (± 37.7) follow-up period, and the collected data covered the period between 2000 and 2016. Using Kaplan-Meier curve and Breslow tests, the data were statistically analyzed. The level of peri-implant bone margins was determined at least every 2 years. Results: Of the 328 implants placed, 2 had to be removed during the follow-up period. All implant superstructures were still in situ at the end of the observation period. The mean overall complication rate was 0.24 per restoration per year for FDPs and 0.37 per year for RDPs. Reasonable therapeutic interventions allowed for preserving and reestablishing the integrity of all implants and full operability of all superstructures. Prosthetic complications occurred about four to five times more frequently than biologic ones; however, according to Breslow test, the distribution of biologic and prosthetic complications was not significantly different (P > .05) when comparing FDPs and RDPs over 10 years. Conclusion: Implant-supported FDPs were not significantly more prone to complications than implant-supported RDPs over time. Prosthetic intervention was required more often than biologic interventions in both approaches.

Purpose: To evaluate the survival of implants and abutments and the incidence of mechanical complications of single posterior implant-supported restorations using prefabricated titanium abutments. Materials and Methods: This retrospective clinical study analyzed 172 Astra Tech OsseoSpeed internal hexagon implants (Dentsply Sirona) placed in 85 patients with a follow-up between January 2009 and January 2019. All implants were restored with prefabricated titanium abutments and cement-retained metal-ceramic crowns. The clinical outcomes recorded were implant and abutment survival rates and mechanical complications (abutment/implant fractures, screw loosening/ fracture, decementation of the superstructure, veneer chipping/fractures) and were analyzed according to age, sex, implant length/diameter, bone graft, arch, implant position, parafunctional habit or dental status, and opposite arch. Kaplan‐Meier survival analysis was used to determine whether the distribution of time to event/failure differed based on implant position (premolar or molar), implant diameter, or abutment angulation. Results: During the observation period (mean: 108 months), implant and abutment cumulative survival rates were 97.7% and 98.3%, respectively, with no statistically significant differences between implant positions (molar/premolar), implant diameters (3.5 vs 4 mm), or abutment angles (straight vs 15 degrees). Of the 172 single posterior implant-supported restorations, 14 mechanical complications (8.2%) were recorded. In particular, 3 abutment fractures (1.7%), 2 screw loosenings (1.2%), 2 screw fractures (1.2%), 1 implant fracture (0.6%), 2 chipping/fractures of veneering materials (1.2%), and 4 decementations of the superstructure (2.3%) occurred. Conclusion: The single posterior implant-supported restorations using prefabricated titanium abutments remain a clinically acceptable treatment in terms of prosthetic procedure and costeffectiveness.

Purpose: To assess oral health–related quality of life (OHRQoL) in edentulous subjects before and after 3, 6, 9, and 12 months of oral rehabilitation with conventional complete dentures (CDs) and to compare their OHRQoL to dentate subjects. Materials and Methods: A total of 148 subjects were selected and divided into three groups: G1 = edentulous in maxillary arch (n = 68, mean age = 61.37 ± 8.91 years); G2 = completely edentulous (n = 50, mean age = 65.14 ± 8.91 years); and G3 = control group (dentate, n = 30, mean age = 60.03 ± 6.88 years). OHRQoL was assessed using the Brazilian version of the Oral Health Impact Profile-Edentulous (OHIP-EDENT) questionnaire at four different times: baseline (pretreatment) and 3, 6, 9, and 12 months after oral rehabilitation with a new CD. The data showed nonparametric distribution and were submitted to Kruskal-Wallis test (α = .05). Results: The impact of OHRQoL was higher for the edentulous groups compared to the control group at baseline (P < .05). Treatment significantly improved OHRQoL after 3 months of prosthesis use, and this effect was maintained during all 12 months of evaluation (P > .05). Conclusion: Oral rehabilitation with conventional CDs in one or both arches improved OHRQoL in edentulous patients after 3 months of prosthesis use, and its effect was maintained for up to 12 months.

Purpose: To evaluate the electromyographic (EMG) activity of masseter muscles (MMs) after the provision of new complete dentures (CDs) and to assess the possible correlations between clinical behavior and the EMG findings. Materials and Methods: The sample included 78 edentulous participants (56 women, 22 men; mean age: 65.59 ± 10.47 years). Prior to provision of the new CDs, surface EMG activity of the masseter muscles was recorded during rest, maximum voluntary contraction, and mastication (MAST) using a wax artifact (WA). The tests were repeated using the new CDs, followed by the WA, at 7 days, 14 days, 21 days, and 10 months. At each assessment after placement of the CDs, the participants were questioned regarding five parameters (comfort, esthetics, retention, mastication, and speech). Results: There was an initial decline in the EMG activity of the masseter muscles after the provision of new CDs during MAST, followed by a gradual increase in this activity over time (P > .05). There was a significant improvement in MAST reported by participants at 10 months (3.59 ± 1.141) compared to 7 days (2.50 ± 1.058) (P = .011). There was no significant correlation between the EMG findings and the clinical parameters (P > .05). Conclusion: Although there was no significant difference in EMG activity of the MMs over time, an improvement in MAST reported by the participants was observed.

Purpose: To establish a recording method for edentulous arch relations and to perform quantitative accuracy evaluation in vitro. Materials and Methods: Edentulous maxilla and mandible models with complete dentures were mounted on an articulator simulating arch relations in protrusion (A), left and right laterotrusion (B and C, respectively), and small opening (D) positions, aided by a metal foil wax record. In the test group, a tracking system was used to record the 3D trajectories of targets from intercuspation to positions A, B, C, and D, and the average of these trajectories was used for rehabilitation of the digital arch relations of A, B, C, and D. In the control group, the six pairs of positioning cylinders were pasted on the axial model surfaces. The center points of the bottom surfaces of the cylinders in the A, B, C, and D positions were measured for rehabilitation of digital arch relations in the control group. With the maxilla as the common area, the arch relations in the test group were registered with the control group, the 3D deviations of the mandible were calculated, and displacements in the horizontal left/right, horizontal anterior/posterior, and vertical directions were analyzed. Results: Three-dimensional deviations of the mandible in the A, B, C, and D positions were 131 ± 39 μm, 133 ± 44 μm, 120 ± 51 μm, and 112 ± 52 μm, respectively. The mean absolute values of displacement in the mandible were less than 200 μm. Conclusion: By using the optical jaw-tracking system, the accuracy of arch-relation records as measured on an articulator was acceptable for clinical demand. Further investigations among patients are required to clinically verify the results of this study.

Purpose: To compare the retention forces of implant overdenture patrices (ball, bar, and TiSi.snap) to conventional (O-ring, metal housing, and plastic clip) and polyvinyl siloxane (PVS)–based silicone (Retention. sil 200, 400, and 600; Mucopren Soft; and GC Reline Soft) matrix materials. Materials and Methods: Two implant analogs in which the patrices were to be placed were embedded parallel to each other in polyethylene blocks, and the matrices were placed in heat-polymerized acrylic blocks that were fabricated as overdentures. Ten samples were prepared for each attachment type, and 180 samples were obtained from 18 groups. All samples were placed in a chewing simulator for occlusal force application and for insertion and removal of the pieces. Retention measurements were performed with a universal testing device at the initial (10 cycles), simulated first-year (1,825 cycles), and simulated second-year (3,650 cycles) periods, assuming that the patients would insert and remove their overdenture five times daily. Results: Loss of retention occurred in all of the attachment systems at the end of 3,650 cycles (P < .05). The PVS matrix materials showed less retention than the O-ring and metal matrices when a ball patrix was used, while they had higher retention than clips when the Hader bar patrix was used (P < .05). Among the PVS matrix materials, Retention.sil 200 produced the lowest retention values, whereas Retention.sil 600 generated the highest. Conclusion: PVS matrix materials showed higher retention than achieved by yellow plastic bar matrices; however, these materials exhibit lower retention than plastic and metal matrices with ball abutments.

Purpose: To evaluate the marginal fit of zirconia (Zi) CAD/CAM crowns in terms of gap and overhang compared to lithium disilicate (LDS) CAD/CAM crowns, as well as the effect of finish line design on marginal accuracy. Materials and Methods: Stone dies were acquired from two master metal dies with two different finish lines (n = 20 each) and scanned to produce digital models. Ceramic crowns (ZS-Ronde [Zi] and IPS e.max CAD [LDS]) were designed and milled on the resulting 40 dies: 10 Zi-shoulder, 10 Zi-chamfer, 10 LDS-shoulder, and 10 LDS-chamfer. Marginal gap and overhang were evaluated at six designated margin locations. The data were obtained, and the influence of material and finish line on the marginal fit of crowns was assessed using two-way analysis of variance and Bonferroni multiple comparisons test (α = .05). Results: The mean marginal gap and overhang on Zi crowns were 30 ± 14 μm and 79 ± 27 μm, respectively, for the shoulder, and were 68 ± 34 μm and 104 ± 34 μm, respectively, for the chamfer. The corresponding values for LDS crowns were 57 ± 22 μm and 74 ± 29 μm for the shoulder and 62 ± 12 μm and 59 ± 27 μm for the chamfer. ANOVA revealed that the differences in marginal gap between the two materials were not significant (P > .05), but that the finish line effect and interaction were significant (P < .05). With regard to marginal overhang, significant differences were found between Zi and LDS crowns (P < .05), although the finish line geometries did not show any significant differences (P > .05). LDS crowns showed no differences between shoulder and chamfer margins for gap or overhang (P > .05), whereas significant differences were found in marginal gap between the Zi shoulder and chamfer margins (P < .005). Conclusion: In terms of marginal accuracy, shoulder margins produced smaller marginal gaps compared to chamfers in Zi CAD/CAM crowns.

Purpose: To perform application of universal bonding agent based only on the manufacturer's instructions for CAD/CAM-manufactured feldspathic and hybrid ceramics and to investigate the bond strength of the composite resin to these ceramics. Materials and methods: A total of 120 samples (2-mm thickness) were obtained from three different CAD/CAM-manufactured ceramics each: a feldspathic ceramic (Vitablocs Mark II), a hybrid ceramic (Cerasmart, GC), and a dual-network ceramic (Vita Enamic). Each of these restorative materials was divided into six subgroups (n = 20 each) in order to apply universal adhesives: All-Bond Universal, Clearfil Quick Universal, Premio Bond, Optibond XTR, Prime&Bond, and Tokuyama Universal Bond. Each bonding agent was applied according to the manufacturer's instructions. Microshear bond strength test was performed at a crosshead speed of 1 mm/min. Two-way analysis of variance (ANOVA) and Tukey post hoc tests were used for statistical analyses. Results: The data suggested a significant impact of bonding agent on all restorative materials applied (P < .001); however, only Prime&Bond demonstrated different effects between materials, with a significant difference between Vitablocs Mark II and Cerasmart restorative materials (P = .001). Conclusion: All universal bonding agents provided an acceptable bond strength for each ceramic. Since different universal bonding agents affected the bond strength between ceramics and composite resin, selecting the most suitable bonding agent for each material will increase the bond strength and clinical success.

Purpose: To develop and assess lemongrass-incorporated tissue conditioners (LG-TCs) with a potent and long-lasting inhibitory effect against Candida albicans cultures to control the accumulation of fungi. Materials and Methods: LG essential oil with concentrations of 7.17%, 3.56%, 1.77%, and 0.89% (w/w) or nystatin were mixed with the liquid part of the TC before being added to the powder part to form 486 TC samples of 6-mm diameter × 2-mm thickness (n = 81 samples for each group of LG-/nystatinincorporated or unmodified TCs). After being immersed in 37°C water for 1, 2, 3, 5, 7, 9, 12, or 14 days, these TC samples were removed, blotted with sterile filter paper, and then exposed to fungal suspension (1 × 105 CFU/mL). The TC samples were evaluated for their capacity to inhibit fungal growth by 99.9%. Results: The anti-Candida effect of the unmodified TCs was reduced significantly after the samples were immersed in water. Interestingly, a long-lasting anti-Candida effect was observed in the TCs incorporated with LG essential oil. After being immersed in water for at least 14 days, the TCs with 1.77% LG oil were still able to inhibit fungal growth substantially. In contrast, a shorter-lasting (5 days) anti-Candida effect was found in the TCs with 0.89% (w/w) LG oil. Additionally, the TCs incorporated with LG oil at concentrations of 3.56% (w/w) or more inhibited the growth of the fungus by 99.99%, and its anti-Candida effect lasted for 14 days. Conclusion: LG-TCs showed an impressive and long-lasting inhibitory effect against C. albicans.

Purpose: To describe the possible adverse effects of sodium hypochlorite (NaOCl) solutions, highconcentration alcohol solutions, and povidone-iodine products indicated for disinfection of inanimate surfaces against human coronavirus of the severe acute respiratory syndrome (SARS-CoV) on prosthesis materials, including zirconia, lithium disilicate, and acrylic resin. Materials and Methods: A systematic literature research was conducted in the SCOPUS, PubMed/Medline, Web of Science, EMBASE, and Science Direct databases from January 2010 to February 2020 using a combination of the following MeSH/Emtree terms and keywords: “sodium hypochlorite”; “alcohol”; “ethanol”; “povidone-iodine”; “dental ceramic”; “zirconia”; “lithium disilicate”; and “acrylic resin”. Results: A total of 538 studies were identified in the search during initial screening, 44 were subject to full-text evaluation, and 24 fulfilled the inclusion criteria. Seven articles on zirconia and lithium disilicate investigated the effect of NaOCl (0.5% and 1%), 96% isopropanol, and 80% ethanol on bond strength after saliva contamination. The remaining articles evaluated color alteration, surface roughness modifications, decrease in flexural strength, and bond strength of all cleaning agents on acrylic resin. Conclusion: NaOCl solution (1%) for 1 minute is recommended to reduce SARSCoV infectivity and to minimize the risk of cross-contamination through prosthetic materials. An increase in surface roughness and color alteration on acrylic resin were recorded using 1% NaOCl, but without any clinical significance. A decrease in bonding strength was determined after using 1% NaOCl, 96% isopropanol, or 80% ethanol solutions on lithium disilicate. Silanization before the try-in procedure and the application of a second layer of silane after cleaning methods are recommended to improve the bond strength.

Purpose: To evaluate the trueness of one stationary and two mobile systems for 3D facial scanning. Materials and Methods: Twenty participants were included in this study. After marking facial soft tissue landmarks, their faces were scanned using three facial scanning systems: the Bellus3D Dental Pro app on an iPad Pro 2020 (Apple; IP); the ARC-7 Face Scanning System (Bellus3D; BA); and the EinScan Pro 2X Plus (Shining 3D Tech; EP) following the manufacturers’ operating instructions. Three-dimensional images were reconstructed with corresponding software and saved in object (OBJ) file format. The interlandmark distances were measured and compared to direct caliper measurements, and absolute error (AE) was chosen as the measurement to determine the trueness of the three scanners. The normal distribution and variance of homogeneity were measured, and then the data were analyzed using one-way ANOVA or Kruskal-Wallis H test. The significance level was set at P = .05. Results: For the measurement of interlandmark distances, no significant differences were found among the four measuring techniques, and the mean AEs of the IP, BA, and EP systems were 1.17 ± 0.80 mm, 0.76 ± 0.61 mm, and 0.69 ± 0.65 mm. Conclusion: The three facial scanning systems tested provided a reliable 3D facial reconstruction. The portable IP system could meet the clinical requirements for facial scanning, but it is suggested to select the EP and BA systems when a higher trueness is required.

Purpose: To digitally evaluate the volumetric wear of four different implant crown materials and their antagonists after artificial aging using an intraoral scanner (IOS) device and a laboratory desktop scanner. Materials and Methods: A total of 48 implants were restored with monolithic crowns and divided into groups according to restorative material: lithium disilicate (LDS); zirconia (ZR); polymer-infiltrated ceramic network (PICN); and porcelain fused to metal (PFM). Each specimen was scanned using a desktop scanner (LAB group; iScan D104, Imetric 3D) and an IOS device (IOS group; Trios 3, 3Shape) before and after chewing simulation (1,200,000 cycles, 49 N, steatite antagonist, 5°C to 50°C). The obtained STL files were superimposed, and the volumetric loss of substance of the crowns and their antagonists was quantified. Kruskal-Wallis, Spearman ρ, and paired t tests were used to analyze the data (α = .05). Results: The mean volume loss for each restorative material varied between 0.05 ± 0.06 mm3 (ZR/IOS) and 3.42 ± 1.65 mm3 (LDS/LAB). The wear of the antagonists was significantly lower (P < .05) for ZR than the other groups. Increased wear of the crowns was highly correlated with increased wear of their antagonists (rs = 0.859). When comparing the wear measurement using the two scanning devices, no difference in mean volume loss was found (IOS: 1.81 ± 1.81 mm3; LAB: 1.82 ± 1.78 mm3) (P = .596). Conclusion: Polished ZR was the most wear-resistant material and the least abrasive to the respective antagonist among the tested ceramics. For quantification of wear, this IOS device can be used as an alternative to desktop scanners.