Comparison of bond strength to three restorative materials after contamination and the use of two cleaning agents.

STATEMENT OF PROBLEM: Scientific data on the decontamination effectiveness of a newly introduced cleaning agent are lacking. PURPOSE: The purpose of this in vitro study was to evaluate and compare the tensile bond strength (TBS) of 3 different restorative bonding surfaces after contamination with saliva following different cleaning protocols. MATERIAL AND METHODS: A total of 192 disk specimens were made out of 3 materials (n=64); Katana Avencia (A), Katana Zirconia (Z), and e.max CAD (L). The bonding surfaces of all disks were polished, steam cleaned, and then pretreated by following the recommended protocol for each material. The specimens of each group were divided into 4 subgroups (n=16). The first subgroup served as the reference (R), where no contamination was applied. The 3 other subgroups were contaminated with saliva and subsequently rinsed with water for 20 seconds and dried with oil- and water-free air spray. They were then either not treated with any cleaning method (0), cleaned with Katana Cleaner (K), or cleaned with Ivoclean (I). The bonding surfaces of the specimens were perpendicularly luted to plexiglass tubes filled with dual-polymerizing composite resin (Clearfil DC Core) with resin cement (Panavia V5) after the recommended surface conditioning. Each subgroup was further subdivided into 2 groups: stored in 37 °C water for 3 days or subjected to thermal-cyclic loading for 150 days with 37 500 thermal cycles (7500 per month), temperature 5 to 55 °C, and dwell time of 30 seconds. All specimens were subjected to TBS testing in a universal testing machine. Three-way ANOVA was applied. A significant interaction (P<.01) was detected between the 3 different variables (material, treatment, aging). After significant interactions had been revealed by 3-way ANOVA, additional statistical analysis was performed by using separate 2-way ANOVAs, then separate 1-way ANOVAs followed by the Tukey-HSD test for post hoc pairwise comparisons among groups (α=.05 for all tests). All specimens underwent failure mode analysis after TBS testing RESULTS: All specimens survived the storage with thermocycling except for group Z-0, where all specimens debonded during thermocycling. The mean ±standard deviation TBS values ranged from 18.3 ±5.3 MPa to 34.0 ±5.4 MPa after 3 days and from 6.7 ±5.5 MPa to 26.9 ±5.4 MPa after 150 days. CONCLUSIONS: Contaminated groups that did not receive any cleaning had significantly lower TBS. Thermocycling had a negative effect on the TBS but was not statistically significant for all groups. Using the same cleaning method, the restorative material did had a significant effect on the TBS after 150 days.

Long-term clinical outcome of three-unit fixed-fixed posterior zirconia ceramic inlay-retained FDPs with a modified design.

OBJECTIVES: To assess the long-term clinical outcome of posterior inlay-retained fixed dental prostheses (IRFDPs) with a modified design made from zirconia ceramic. METHODS: In 30 patients thirty 3-unit IRFDPs were placed to replace 7 premolars (4 in the maxilla, 3 in the mandible), and 23 first molars (15 in the maxilla, 8 in the mandible). Preparations were accomplished in agreement with the general principles for ceramic inlay restorations and modified with a short retainer-wing bevel preparation within the enamel at the buccal and oral sides. The frameworks were milled from 3Y-TZP ceramic, and the pontics were veneered with feldspathic ceramic. All IRFDPs were bonded with a phosphate monomer containing luting resin after air-abrasion of the intaglio surfaces. The patients were recalled 6-12 months after placement, and then annually. Kaplan-Meier analysis was used to calculate the survival and complication rates of the IRFDPs. RESULTS: The mean observation time was 10.6 ± 1.5 years. The 10-year cumulative survival rate was 89% with 4 failures, two of them were due to deep secondary caries with loss of retention, one due to repeated debonding with enamel fractures, and one due to generalized progressive periodontitis. The most common complication was chipping of the veneering ceramic (20.1%). Eighteen IRFDPs were free of any type of complication up to 15.4 years, which corresponds to a 10-year cumulative success rate of 70.4%. CONCLUSION: The long-term clinical performance of modified IRFDPs made of veneered zirconia ceramics was favorable after 10 years, therefore, they represent a treatment alternative to replace posterior single missing teeth. CLINICAL SIGNIFICANCE: Zirconia-based IRFDPs fabricated in the modified design may represent a substance-preserving alternative to conventional posterior FDPs to replace posterior single missing teeth, particularly in cases where implants cannot be placed, and when the adjacent teeth already have small restorations or defects.

Effects of sterilization, conditioning, and thermal aging on the retention of zirconia hybrid abutments: A laboratory study.

OBJECTIVE: To investigate the effects of sterilization, conditioning method, and thermal aging on the retentive strength of two-piece zirconia abutments. MATERIALS AND METHODS: In total, 128 stock zirconia abutments were divided into four groups (n = 32) according to the conditioning parameters: (A) air-abrasion using 50 µm alumina particles/1.0 bar, (B) 50 µm/2.0 bar, (C) 100 µm/1.0 bar, and (D) 100 µm/2.0 bar. All abutments were bonded onto titanium bases using DTK adhesive resin and stored in water bath (37°C) for 72 h. Each group was subdivided into two subgroups (n = 16), group 1 was disinfected, whereas group 2 followed disinfection and autoclave sterilization. Half of the specimens of each subgroup (n&#x02009;=&#x02009;8) was directly subjected to the axial retention test (groups N), while the other half was first subjected to 150&#x02009;days of thermocycling followed by retention test (groups T). Statistical analysis was performed with three-way ANOVA, additional statistical analysis was performed by using separate one-way ANOVAs followed by the Tukey's post-hoc test for post hoc pairwise comparisons among groups. RESULTS: The highest median retention strength was recorded for group B2N (1390 N), whereas the lowest strength was recorded for group C1T (688 N). No significant interaction (p ≥ 0.05) was detected between the different variables; conditioning method, sterilization, and the thermal cycling regarding the effect on the resulting retention. However, the sterilization always showed a positive effect. Thermocycling presented an adversely significant effect only in the absence of sterilization (p < 0.05), with the exception of subgroups A. For the sterilized groups, thermocycling had no statistically significant effect on the retention. CONCLUSION: Steam autoclaving increased the retention of hybrid zirconia abutments. DTK adhesive resin for two-piece zirconia abutments performed well after sterilization and thermocycling.

The Effect of Sterilization on the Accuracy and Fit of 3D-Printed Surgical Guides.

This study was conducted to evaluate the accuracy of 3D-printed surgical guides before and after sterilization in a steam sterilizer. A test-model incorporating three implant replicas was customized. A total of forty guides were printed from five printable resins. A group made from a self-curing composite served as control group. The guides were checked for fit. Vertical discrepancies between the model and guides were measured at standardized points at a load of 500 g (P1). The guides were connected to implant replicas and scanned, and their angles were digitally measured. The specimens were sterilized in a steam sterilizer at 121 °C for 20 min at 2 bar pressure. Vertical discrepancies (P2) and angulations were remeasured. Additionally, the specimens were repositioned with an increased load, and measurements were repeated (P3). All specimens were repositionable after sterilization. The smallest variation in discrepancy at a 500 g load was 428 µm, whereas the greatest was 1487 µm. Under an increased force, the smallest change was 94 µm, while the greatest was 260 µm. The level of significance α = 0.05 (95% confidence interval) was set for all tests. The variation in the measured angles was not statistically significant (Kruskal-Wallis's test, p > 0.05). The accuracy was affected by the material and sterilization, but it was clinically acceptable when an increased load was applied during repositioning.

Resin-bonded attachments made of monolithic zirconia ceramic: a minimally invasive and esthetic treatment approach.

OBJECTIVE: The aim of this case report was to present a minimally invasive and esthetic treatment approach for the replacement of missing teeth removable partial dentures retained by zirconia ceramic resin-bonded attachments. METHOD AND MATERIALS: The resin-bonded attachments were digitally designed and milled using CAD/CAM technology from monolithic 3Y-TZP zirconia ceramic. The resin-bonded attachments had an optimized attachment design approved for zirconia ceramic. The preparation was based on general preparation guidelines for resin-bonded attachments and resin-bonded fixed dental prostheses (RBFDPs). After placement of rubber dam, the resin-bonded attachments were bonded with a phosphate monomer-containing luting resin. RESULTS: The presented resin-bonded attachment-retained removable partial denture was successful over 30 months of clinical observation without any complications. The patient was satisfied with the minimally invasive treatment procedure. CONCLUSION: Zirconia ceramic resin-bonded attachments fabricated with a special attachment design are an esthetic and minimally invasive treatment approach. However, clinical data on the long-term outcome of zirconia resin-bonded attachments are still needed. (Quintessence Int 2023;54:220-226; doi: 10.3290/j.qi.b3819523).

Effect of Thermomechanical Dynamic Loading on the Retention of Metallic and Nonmetallic Telescopic Mandibular Overdentures.

PURPOSE: To evaluate the effect of thermomechanical dynamic loading on the retention of telescopic mandibular overdentures with different metallic and nonmetallic material combinations. MATERIALS AND METHODS: Four groups were tested: (1) ZP (zirconia abutments/PEEK framework); (2) PP (PEEK abutments/PEEK framework); (3) TP (titanium abutments/PEEK framework); and (4) TG (titanium abutments/gold copings/cobalt-chromium framework). Each specimen contained four implants positioned over a polyvinylchloride-cylindrical base. After 10,000 removal/insertion cycles, the specimens were subjected to thermomechanical dynamic load in a chewing simulator for 1,200,000 loading cycles, corresponding to 5-year clinical fatigue. A screw was used to receive the chewing load, and 0.5 mm was permitted between the screw and the metal top fixed into the base to simulate the resilience of the posterior residual ridge tissues. Vertical chewing loads of 60 N were applied at a speed of 30 mm/second. Thermocycling was applied with a temperature ranging between 5°C and 55°C. The retentive force was measured using a universal testing machine 10 times before and after the thermomechanical dynamic loading test with a speed of 8 mm/second. RESULTS: The mean retentive force increased significantly from 13.2 (± 4.6) N to 16.4 (± 6.1) N in group ZP (P = .002), while in group TP, it decreased significantly from 4.9 (± 2.1) N to 3.3 (± 1.7) N (P = .046). There was no statistically significant change in the retentive force for groups PP and TG. CONCLUSIONS: The investigated metallic and nonmetallic combinations of double-crown-retained mandibular overdentures maintained acceptable levels of retention after thermomechanical dynamic loading. Further laboratory and clinical studies are needed before their routine clinical use can be recommended.

Prosthetic restoration after atraumatic surgical extrusion: a report of two cases.

Preservation and restoration of teeth with little coronal tooth structure due to crown-root fractures or caries lesions, ensuring restoration margins do not encroach on the biologic width, constitute a challenge. Available treatment options include surgical crown lengthening and orthodontic or surgical extrusion. This report presents two patients in which teeth were restored by surgical extrusion with an atraumatic extraction system and prosthetic therapy.

Effect of thermo-mechanical dynamic loading on the retention of metallic and non-metallic telescopic mandibular overdentures.

PURPOSE: To evaluate the effect of thermomechanical dynamic loading on the retention of telescopic mandibular overdentures with different metallic and nonmetallic material combinations. MATERIALS AND METHODS: Four groups were tested: (1) ZP (zirconia abutments/PEEK framework); (2) PP (PEEK abutments/PEEK framework); (3) TP (titanium abutments/PEEK framework); and (4) TG (titanium abutments/gold copings/cobalt-chromium framework). Each specimen contained four implants positioned over a polyvinylchloride-cylindrical base. After 10,000 removal/insertion cycles, the specimens were subjected to thermomechanical dynamic load in a chewing simulator for 1,200,000 loading cycles, corresponding to 5-year clinical fatigue. A screw was used to receive the chewing load, and 0.5 mm was permitted between the screw and the metal top fixed into the base to simulate the resilience of the posterior residual ridge tissues. Vertical chewing loads of 60 N were applied at a speed of 30 mm/second. Thermocycling was applied with a temperature ranging between 5°C and 55°C. The retentive force was measured using a universal testing machine 10 times before and after the thermomechanical dynamic loading test with a speed of 8 mm/second. RESULTS: The mean retentive force increased significantly from 13.2 (± 4.6) N to 16.4 (± 6.1) N in group ZP (P = .002), while in group TP, it decreased significantly from 4.9 (± 2.1) N to 3.3 (± 1.7) N (P = .046). There was no statistically significant change in the retentive force for groups PP and TG. CONCLUSIONS: The investigated metallic and nonmetallic combinations of double-crown-retained mandibular overdentures maintained acceptable levels of retention after thermomechanical dynamic loading. Further laboratory and clinical studies are needed before their routine clinical use can be recommended.

Retention durability of one-retainer versus two-retainer posterior RBFDPs after chewing simulation.

The clinical use of one-retainer RBFDPs in the anterior region has shown higher survival rates compared to conventional two-retainer RBFDPs. The motivation for this study was to assess the validity of this observation when extended to the posterior region. The aim was thus to evaluate different preparation and framework designs for replacing premolars, particularly one-retainer versus two-retainer designs, on the retention of monolithic zirconia posterior RBFDPs. Extracted caries-free human premolars and third molars were embedded in auto-curing resin to create models with an edentulous space of premolar width. Abutment teeth were prepared according to these six designs (n = 8 each): one or two upper retainers with narrow rests, one or two upper retainers with wide rests, and one or two-retainers with wide rests. RBFDPs were milled from monolithic zirconia (KATANA Zirconia HT), and were adhesively bonded using Panavia V5 with corresponding primers. After thermodynamic loading, the quasi-static tensile force required for failure was determined. Failure modes were evaluated using a microscope. Survival rates after thermodynamic loading were 75% for one group (one upper-molar retainer with narrow rest), 100% for the other groups. The debonding forces ranged from 310 ± 224 N (group one upper-molar retainer with narrow rest) to 927 ± 292 N (group two upper retainers with narrow rests). Two-retainer designs failed at significantly higher tensile forces than designs with one retainer (p ≤ 0.05). There were no significant differences between upper and lower designs, or rest widths. Although RBFDPs with two retainers withstood higher debonding forces, RBFDPs with one retainer and wide rest still have a high potential for clinical treatment because of the high forces required for their debonding.

Retention of posterior resin bonded fixed dental prostheses with different designs after chewing simulation.

The aim of this study was to evaluate the effect of different preparation and framework designs on the retention of posterior resin bonded fixed dental prostheses (RBFDPs) made from monolithic zirconia ceramic. Forty-eight caries-free upper premolars and forty-eight upper third molars were used in this study. The teeth were randomly divided into six main groups (n = 8 each) according to the preparation design of two-retainer RBFDPs: narrow or wide rest, combined with 0, 1 or 2 retainer wings. All RBFDPs were milled from monolithic zirconia (KATANA Zirconia ML). They were bonded using Panavia V5 with its corresponding primer, and underwent thermodynamic loading (98 N, 1,200,000 cycles). Retention was evaluated for the surviving RBFDPs in a universal testing machine by means of a debonding test. Failure modes were evaluated using a light microscope. Data was statistically analyzed by Kruskal-Shapiro-Wilk followed by Mann-Whitney with Bonferroni correction for multiple testing. The survival rates after the chewing simulation were 75% (group narrow rest/no retainer wing), 62.5% (group wide rest/no retainer wing) and 100% (the other groups). The mean retention ranged from 31 N to 766 N. Designs with two retainer wings showed significantly higher bond strength than the other designs (p ≤ 0.05). The rest width did not show a significant effect on the retention. Posterior RBFDPs with a modified design (occlusal rest and two retainer wings) exhibited promising durability and retention. Designs with two additional retainer wings should be preferred over designs with one or no retainer wing, irrespectively of the rest width.

Long-term clinical outcome of posterior metal-ceramic crowns fabricated with direct metal laser-sintering technology.

OBJECTIVES: To evaluate the long-term clinical outcome of posterior metal-ceramic crowns fabricated with CAD/CAM-based laser-sintering technology (BEGO Medical, Bremen, Germany). MATERIALS AND METHODS: Sixty posterior crowns were placed in 39 patients. After tooth preparation, impression taking and model casting, the stone dies were scanned to create STL data, followed by manufacturing of crown frameworks with laser-sintering technology. A base metal alloy (CoCr) and a precious alloy (AuPt) were used for 31 and 29 posterior crowns, respectively, which were veneered using the layering technique. All crowns were cemented using glass-ionomer cement. RESULTS: The mean observation period was 10.5 ±â€¯3.9 years. Six patients with 10 crowns were regarded as dropout. Nine crowns had been removed, three of them were intact but they were removed due to a new prosthetic treatment plan. The cumulative survival rate of all crowns was 81% after 14.7 years. When comparing the survival rates related to the alloy used, the Gehan-Wilcoxon test showed no significant differences between both alloys. Biological complications were most commonly reported, while technical complications did not affect the function of the crowns. CONCLUSION: The long-term clinical outcome of posterior metal-ceramic crowns fabricated with CAD/CAM-based laser-sintering technology is very promising, so that this novel technique could be an alternative to the traditional lost wax casting process.

Retention of metallic and non-metallic double-crown-retained mandibular overdentures on implants: An in-vitro study.

PURPOSE: To evaluate the change in the retention of novel metallic and non-metallic combinations for double-crown-retained mandibular overdentures on implants. METHODS: Cylindrical bases were used to insert four implants arranged in an arch, with 10 mm inter-implant spacing anteriorly, and 35 mm posteriorly. Five groups (n = 8 each) of different materials combinations were tested for retention: zirconia abutments/PEEK framework (ZP), PEEK abutments/PEEK framework (PP), titanium abutments/PEEK framework (TP), titanium abutments/CoCr framework (TC), and titanium abutments/gold copings/cobalt-chromium framework as the control group (TG). The abutment retention height was 4 mm with 1° convergence angle. The retention was measured in a wet condition using a chewing simulator initially, and then at 100, 200, 500, 1,000, 2,000, 3,000, 5,000, 8,000, and 10,000 insertion/separation cycles, which simulates the removing and inserting of an overdenture three times daily for 10 years of function. RESULTS: The initial median retention of all groups ranged from 10.0 to 33.3 N. After 10,000 insertion/separation cycles, the median retention ranged from 10.3 to 35.0 N. The change in the retention after 10,000 cycles was not statistically significant within groups ZP and TG. For groups PP and TP, there was a slight increase in retention with partial significance. The retention of group TC showed fluctuation with a partially significant decrease in retention. CONCLUSIONS: The use of novel metallic and non-metallic combinations in the construction of double-crown-retained mandibular overdentures on implants resulted in acceptable levels of retention and might be recommended for clinical application.

Outcome of posterior fixed dental prostheses made from veneered zirconia over an observation period of up to 13 years.

OBJECTIVES: It was the aim of this clinical study to evaluate the long-term outcome of 3- to 4-unit posterior all-ceramic fixed dental prostheses (FDPs) made from veneered zirconia ceramic. METHODS: Between June 2003 and February 2005, 48 patients received 58 restorations. Twenty-four FDPs had a fixed-to-fixed design (FF) and thirty-four FDPs had a cantilever design (CA). Frameworks were scanned and milled out of 3 mol% yttrium-oxide partially-stabilized zirconia ceramic (CerconBase30, Degudent) and were veneered with feldspathic ceramic (CerconCeramS, Degudent). All FDPs were cemented with glass-ionomer cement (Ketac-Cem, 3 MEspe) after air-abrading the inner crown surfaces. RESULTS: The mean observation period was 85.4 ±â€¯54 (FF) and 91.7 ±â€¯50 (CA) months, respectively. Ten cantilever FDPs and 5 fixed FDPs were lost due to biological problems of the abutment teeth. Two cantilever FDPs and 4 fixed-to-fixed FDPs were lost due to technical failures of the ceramic materials. The cumulative 13-year survival rate was 43.2% (FF) (CI: 22.8-66.2%) and 52.5% (CA) (CI: 32.5-71.8), respectively. In 13 cases, intraoral repair or polishing of the fractured feldspathic ceramic veneers was needed (7 in group FF, 6 in CA). Eight abutments of six restorations (4 in FF, 4 in CA) had to be treated endodontically and caries therapy was needed in 6 abutment teeth (4 in group FF, 2 in CA). The cumulative 13-year success rate was 29.5% (FF) (CI: 12.1-55.9%) and 22.5% (CA) (CI: 7.9-49.3%). CONCLUSIONS: Within the limitations of the present investigation, posterior fixed dental prostheses made from veneered zirconia with either a fixed-to fixed or a cantilever design show comparable survival and success rates after 13 years of clinical observation. CLINICAL SIGNIFICANCE: FDPs made from veneered zirconia ceramic present high failure and complication rates, irrespective of the design (fixed-to-fixed or cantilevered).

Five-year clinical outcome of posterior zirconia ceramic inlay-retained FDPs with a modified design.

OBJECTIVES: To evaluate the 5-year clinical outcome of posterior inlay-retained fixed dental prostheses (IRFDPs) with a modified design made from zirconia ceramic (Vita In-Ceram YZ, Vita Zahnfabrik, Bad Säckingen, Germany). METHODS: Thirty 3-unit IRFDPs were placed in 30 patients. Seven IRFDPs replaced the second premolars (4 in the maxilla, 3 in the mandible), and 23 replaced the first molars (15 in the maxilla, 8 in the mandible). Preparations were performed in accordance with general principles for ceramic inlay restorations and modified with a short retainer-wing bevel preparation within the enamel at the buccal and oral sides. The frameworks were milled from zirconia ceramic, and the pontics were veneered with feldspathic ceramic. After air-abrasion of bonding surfaces, IRFDPs were bonded with an adhesive composite resin. The patients were recalled 6-12 months after placement, and then annually. Kaplan-Meier analysis was used to calculate the survival and complication rates of the IRFDPs. RESULTS: After a mean observation time of 64.4 (SD=17.6) months (min 15, max 95.6), the 5-year cumulative survival of IRFDPs was 95.8%. Debonding was reported for two IRFDPs (6.9%), one of them failed finally after 49.4 months due to repeated debonding. Chipping of the veneering ceramic was reported in three cases (10.5%). Secondary caries were reported in 2 patients (8.1%). Nevertheless, the latter complications did not affect the clinical function of the involved IRFDPs. CONCLUSION: The 5-year clinical outcome of zirconia-based IRFDPs fabricated in the modified design is encouraging, so that they may represent a treatment alternative to replace posterior single missing teeth, taking into consideration the appropriate case selection.

All-ceramic inlay-retained fixed dental prostheses: An update.

Inlay-retained fixed dental prostheses (IRFDPs) represent a minimally invasive alternative to conventional fixed dental prostheses (FDPs) to replace single posterior missing teeth. The aim of the present review article is to assess the clinical outcome of different IRFDPs in order to derive recommendations regarding their clinical application. Hence, it is essential to highlight important factors that influence the longevity and success of IRFDPs, such as treatment plan, appropriate case selection with proper indications, as well as tooth preparation. Furthermore, a good understanding of bonding technologies and awareness of pretreatment procedures for different materials are indispensable for the long-term success of IRFDPs.

Ten-year clinical outcome of three-unit posterior FDPs made from a glass-infiltrated zirconia reinforced alumina ceramic (In-Ceram Zirconia).

OBJECTIVES: To evaluate the long-term survival and complication rates of posterior three-unit fixed dental prostheses (FDPs) fabricated from a glass-infiltrated zirconia reinforced alumina ceramic (In-Ceram Zirconia). METHODS: Fifty-eight patients received 65 FDPs. Twelve FDPs replaced the second premolar (8 in the maxilla, 4 in the mandible), and 53 replaced the first molar (19 in the maxilla, 34 in the mandible). The In-Ceram Zirconia ceramic frameworks were designed and milled using the Cerec CAD/CAM system. The minimum dimension of the proximal connectors of the frameworks was 12 mm(2) and 16 mm(2) for premolars and molars, respectively. After milling and glass infiltration, the frameworks were veneered with a feldspathic ceramic. All FDPs were cemented with glass-ionomer cement. The patients were recalled 6-12 months after placement, and then annually. Kaplan-Meier analysis was used to calculate the survival and complication rates of the FDPs. RESULTS: The mean observation time was 9.7 years. Six patients with 6 FDPs were regarded as dropouts. Using the Kaplan-Meier method the 10-year cumulative survival rate was 93.6%. In a worst-case scenario, in which the 6 missing FDPs are considered as failed, the 10-year survival rate would be 84.6%. CONCLUSION: Three-unit posterior FDPs made from In-Ceram Zirconia presented a 10-year survival rate similar to that reported for conventional FDPs. However more technical and biological complications were reported. CLINICAL SIGNIFICANCE: Three-unit posterior FDP made from In-Ceram Zirconia may be a viable treatment modality, taking the strict adherence to the manufacturer's recommendations into consideration.