Group 4 ITI Consensus Report: Patient benefits following implant treatment in partially and fully edentulous patients.

OBJECTIVES: The aim of Working Group 4 was to address patient benefits associated with implant dentistry. Focused questions on (a) dental patient-reported outcomes (dPROs), (b) improvement in orofacial function, and (c) preservation of orofacial tissues in partially and fully edentulous patients following provision of implant-retained/supported dental prostheses were addressed. MATERIALS AND METHODS: Three systematic reviews formed the basis for discussion. Participants developed statements and recommendations determined by group consensus based on the findings of the systematic reviews. These were then presented and accepted following further discussion and modifications as required by the plenary of the 7th ITI Consensus Conference, taking place in 2023 in Lisbon, Portugal. RESULTS: Edentulous patients wearing complete dentures (CD) experience substantial improvements in overall dPROs and orofacial function following treatment with either complete implant-supported fixed dental prostheses (CIFDP) or implant overdentures (IODs). With respect to dPROs, mandibular IODs retained by two implants are superior to IODs retained by one implant. However, increasing the number of implants beyond two, does not further improve dPROs. In fully edentulous patients, rehabilitation with CIFDP or IOD is recommended to benefit the preservation of alveolar bone and masseter muscle thickness. CONCLUSIONS: Completely edentulous patients benefit substantially when at least the mandible is restored using an CIFDP or an IOD compared to CD. In fully edentulous patients, implant prostheses are the best option for tooth replacement. The availability of this treatment modality should be actively promoted in all edentulous communities, including those with limited access and means.

Impact of the material and sintering protocol, layer thickness, and thermomechanical aging on the two-body wear and fracture load of 4Y-TZP crowns.

OBJECTIVES: The aim of this study is to investigate the influence of the material and corresponding sintering protocol, layer thickness, and aging on the two-body wear (2BW) and fracture load (FL) of 4Y-TZP crowns. MATERIALS AND METHODS: Multi-layer 4Y-TZP crowns in three thicknesses (0.5 mm/1.0 mm/1.5 mm) were sintered by high-speed (Zolid RS) or conventional (Zolid Gen-X) sintering. 2BW of ceramic and enamel antagonist after aging (1,200,000 mechanical-, 6000 thermal-cycles) was determined by 3D-scanning before and after aging and subsequent matching to determine volume and height loss (6 subgroups, n = 16/subgroup). FL was examined initially and after aging (12 subgroups, n = 16/subgroup). Fractographic analyses were performed using light-microscope imaging. Global univariate analysis of variance, one-way ANOVA, linear regression, Spearman's correlation, Kolgomorov-Smirnov, Mann-Whitney U, and t test were computed (alpha = 0.05). Weibull moduli were determined. Fracture types were analyzed using Ciba Geigy table. RESULTS: Material/sintering protocol did not influence 2BW (crowns: p = 0.908, antagonists: p = 0.059). High-speed sintered Zolid RS presented similar (p = 0.325-0.633) or reduced (p < 0.001-0.047) FL as Zolid Gen-X. Both 4Y-TZPs showed an increased FL with an increasing thickness (0.5(797.3-1429 N) < 1.0(2087-2634 N) < 1.5(2683-3715 N)mm; p < 0.001). For most groups, aging negatively impacted FL (p < 0.001-0.002). Five 0.5 mm specimens fractured, four showed cracks during and after aging. CONCLUSIONS: High-speed sintered crowns with a minimum thickness of 1.0 mm showed sufficient mechanical properties to withstand masticatory forces, even after a simulated aging period of 5 years. CLINICAL RELEVANCE: Despite the manufacturer indicating a thickness of 0.5 mm to be suitable for single crowns, a minimum thickness of 1.0 mm should be used to ensure long-term satisfactory results.

Fabrication of an implant-retained overdenture with ceramic crowns cemented on a polyetherketoneketone framework: A clinical report.

This clinical report describes the treatment of a complex intraoral situation by fabricating a maxillary implant-retained overdenture with a high-performance polymer (polyetherketoneketone) framework and lithium disilicate crowns and mandibular tooth- and implant-supported ceramic restorations. No complications were noted in 2 years, and the patient was satisfied with function and esthetics.

Biological and technical complications in root cap-retained overdentures after 3-15 years in situ: a retrospective clinical study.

OBJECTIVES: This retrospective clinical study investigates the frequency of biological and technical complications in patients rehabilitated by natural root-retained overdentures (RODs) with cast post-and-cores (root caps) wearing precision attachments and analyses factors influencing complication rates (e.g. oral hygiene routines). MATERIALS AND METHODS: Patients formerly treated with RODs were invited for a cost-free clinical visit to evaluate their intraoral status. Furthermore, they were interviewed and patient records were screened for complications occurring since denture delivery. Statistical models include descriptive analyses, Fisher's exact test, odds ratios, and a multivariate regression model. RESULTS: A total of 114 patients wearing 128 RODs with a total of 280 abutment teeth were evaluated (mean service time: 7.9 years). Technical complications occurred in 68.8% of the RODs, with matrix loosening being the most frequent complication (50.1%). Biological complications occurred in 53.9% of all RODs, with the presence of denture stomatitis being the most common biological complication (38.3%). The presence of denture stomatitis was significantly higher in the maxilla relative to the mandible (p = 0.0029), in subjects cleaning their dentures less than twice a day (p < 0.001), in subjects regularly using CHX-containing products (p = 0.036) and in subjects with a plaque index > 40% (p < 0.001). CONCLUSIONS: Root cap-retained overdentures with precision attachments are a viable treatment option in partially dentate subjects, even over long-term periods. However, high complication rates should be expected. CLINICAL RELEVANCE: Establishing good oral hygiene is a decisive factor in preventing complications in RODs. Furthermore, CHX-containing products may not be recommended for routine domestic use.

Mandibular two-implant overdentures with CAD-CAM milled bars with distal extensions or retentive anchors: A randomized controlled trial.

OBJECTIVE: This randomized controlled trial (RCT) aimed to demonstrate the non-inferiority of mandibular 2-implant overdentures (IODs) on a CAD-CAM milled bar with long distal extensions (MBDE) against IODs on retentive anchors (RA). METHODS: Forty edentulous participants rehabilitated with a maxillary conventional denture and a mandibular 2-IOD participated in this trial. They were randomized into two groups [Control group (CG): RA + gold matrices; Experimental group (EG): MBDE + gold clip]. The outcomes included implant survival rate (ISR), chewing efficiency [quantitative (VoH) and subjective (SA) assessments], peri-implant marginal bone levels (PI-MBL), maximum bite force (MBF), and patient-reported outcomes [oral health impact profile (OHIP-EDENT), and denture satisfaction index (DSI)]. Outcomes were recorded at baseline (BL), two weeks (T0 ), 6 months (T1 ), and at 1 year (T2 ) after the intervention. Intra- and inter-group analyses were performed using regression models with ⍺=0.05. RESULTS: 38 participants completed the T2 visit (CG: n = 19, age = 74.7 ± 7.8 years; EG: n = 19, age = 70.3 ± 10.7 years). At T2 , there was no implant loss in either of the groups (ISR = 100%). There were no significant differences between the groups for the PI-MBL changes (p = .754). Improvements occurred faster in the EG than in the CG, but over the observation time, there were no differences between the trial groups for VoH, MBF, OHIP-EDENT, and the DSI, except for SA being significantly better in the EG group (p = .022). CONCLUSIONS: The results of this RCT confirm that mandibular 2-IODs with a CAD-CAM milled bar with long distal extensions are not an inferior treatment to the conventional IODs on retentive anchors in the short term (1 year).

Influence of surgical guide support and implant site location on accuracy of static Computer-Assisted Implant Surgery.

OBJECTIVE: To investigate the effect of surgical guide support and implant site location on the accuracy of static Computer-Assisted Implant Surgery (sCAIS) in partially edentulous patients. MATERIALS AND METHODS: 375 replica implants were inserted in 85 study models. Surgical implant placement was done using static 3D printed surgical guides, which were designed to be supported either by all the teeth present in the model (full arch), or by 4-teeth), 3-teeth or 2-teeth. Each study model included three single-tooth gap (STG) situations; one extraction socket site and two implants placed in a distal extension situation. Preplanned and postoperative implant positions were compared using the treatment-evaluation tool in digital software. 3-dimensional and angular deviations were measured. Statistical analysis was done using ANOVA, and pairwise t tests and Bonferroni-Holm's adjustment were applied as a post hoc test. RESULTS: Accuracy of surgical guides used in sCAIS was significantly affected by the number and type of teeth used for its support. Guides supported by 4 teeth were not significantly different from accuracy of full-arch-supported guides (p > .05). Guide support by posterior teeth was associated with an increased level of accuracy, when compared to anterior teeth guide support. Implants placed in extraction sockets were associated with significantly higher 3D and angular deviation values (p < .05), and surgical guides with a distal extension situation resulted in significantly higher deviation values (p < .05). CONCLUSION: The number and location of teeth supporting the surgical guide can significantly influence the accuracy of sCAIS, with 4 teeth providing equal accuracy to full-arch guides in (STG) situations.

Validation of a purpose-built chewing gum and smartphone application to evaluate chewing efficiency.

OBJECTIVES: To validate a purpose-built two-coloured chewing gum (Hue-Check Gum® ), and to test the accuracy of a custom-built smartphone application for a colour-mixing ability test to assess chewing function. METHODS: Fully dentate participants (28D-group) and edentulous participants with implant overdentures (IOD-group) were recruited. They chewed a Hue-Check Gum® for 5, 10, 20, 30 and 50 chewing cycles, respectively. Maximum voluntary bite force (MBF) was assessed with a digital gauge. The specimens were analysed according to their colour mixture (variance of hue, VOH) with a validated software (VOH_scan) and a newly developed smartphone application (VOH_app). RESULTS: Participants segregated by dental state were significantly different regarding the number of occluding pairs of teeth, age and MBF. VOH_scan showed a negative logarithmic association with the number of chewing cycles, and VOH could be predicted from chewing cycles, MBF and gender. The clearest discrimination between the IOD and the 28D groups was observed for n = 20 chewing cycles; at this point, VOH was distinguishably different with a P-value < 0.0001. The VOH_app was a very good predictor for VOH_scan with 0.80 < pseudo-R2  < 0.83, depending on light exposure and measuring distance. There was, however, a systematic error in the accuracy of the app for inadequately chewed specimens. CONCLUSIONS: The use of the two-coloured chewing gum would provide a fast, simple and inexpensive method for the assessment of masticatory performance, which could be used in geriatric wards or in private practices without the requirement of specialised equipment or trained staff.

Load bearing capacity of 3-unit screw-retained implant-supported fixed dental prostheses with a mesial and distal cantilever on a single implant: A comparative in vitro study.

OBJECTIVES: To assess the mechanical durability of monolithic zirconia implant-supported fixed dental prostheses (iFDP) design on one implant, with a distal and a mesial extension cantilever bonded to a titanium base compared to established designs on two implants. MATERIALS AND METHODS: Roxolid Tissue level (TL), and tissue level x (TLX) implants were used to manufacture screw-retained 3-unit iFDPs (n = 60, n = 10 per group), with following configurations (X: Cantilever; I: Implant, T: Test group, C: Control group): T1: X-I-X (TL); T2: X-I-X (TLX); T3: I-I-X (TL); T4: I-I-X (TLX); C1: I-X-I (TL); C2: I-X-I (TLX). The iFDPs were thermomechanically aged and subsequently loaded until fracture using a universal testing machine. The failure load at first crack (Finitial) and at catastrophic fracture (Fmax) were measured and statistical evaluation was performed using two-way ANOVA and Tukey's post-hoc tests. RESULTS: The mean values ranged between 190 ± 73 and 510 ± 459 N for Finitial groups, and between 468 ± 76 and 1579 ± 249 N for Fmax, respectively. Regarding Finitial, neither the implant type, nor the iFDP configuration significantly influenced measured failure loads (all p > 0.05). The choice of implant type did not show any significant effect (p > 0.05), while reconstruction design significantly affected Fmax data (I-I-Xa < X-I-Xb < I-X-Ic) (p < 0.05). The mesial and distal extension groups (X-I-X) showed fractures only at the cantilever extension site, while the distal extension group (I-I-X) showed one abutment and one connector fracture at the implant/reconstruction interface. CONCLUSION: Results suggest that iFDPs with I-X-I design can be recommended regardless of tested implant type followed by the mesial and distal extension design on one implant abutment (X-I-X).

A New Implant System with Directly Screwed Supraconstructions: Impact of Restoration Material and Artificial Aging on the Bending Moment.

PURPOSE: To investigate the bending moment of implants restored with a directly screwed single-unit fixed dental prosthesis (FDP) compared to implants restored with an FDP polymerized to a titanium base before and after thermomechanical aging. MATERIALS AND METHODS: A total of 240 implants (120 with and 120 without a titanium base) were restored with FDPs manufactured from conventionally sintered 3Y-TZP, 5Y-TZP, 4Y-TZP, and CoCrMo, as well as high-speed sintered 4Y-TZP. Half the specimens per subgroup were aged using chewing simulation combined with thermocycling (1,200,000 cycles at 50 N; 6,000 cycles at 5° to 55°). Initial and aged fracture load were measured. The bending moment was calculated and subjected to statistical analysis (Kolmogorov-Smirnov test, one-way ANOVA followed by post hoc Scheffé, t, and chi-square tests; P < .05). Failure types were analyzed. RESULTS: Implants without a titanium base showed higher bending moments for all initially tested zirconia groups compared to implants with a titanium base. The highest initial values were observed for 4Y-TZP FDPs regardless of implant type. High-speed sintered FDPs demonstrated higher initial bending moments compared to conventionally sintered FDPs. Artificial aging led to a decrease of the bending moment in most subgroups. After aging, no differences were found within the restoration materials, sintering protocols, or implant types. Implant deformation occurred mainly with directly screwed FDPs, whereas FDP mobility was predominantly observed among implants with a titanium base. FDP fractures were mainly observed for 5Y-TZP. CONCLUSIONS: Both implant types exhibited similar values after aging. Thus, implants without a titanium base seem to show equally sufficient stability for clinical applications with all tested materials.

Mesiodistal Measurements for Dental Implant Planning: A Prospective Clinical Study of Linear Measurements on Cone-Beam Computed Tomography Images in Comparison with Caliper-Based Measurements on Plaster Casts.

Althouh cone beam computed tomography (CBCT) is popular for dental implant planning, the horizontal mesiodistal space of the edentulous ridge is still conventionally measured with a handheld sliding caliper in the oral cavity or on a plaster cast. For clinical application in implant planning, our aim was to evaluate the accuracy of CBCT horizontal mesiodistal linear measurements in comparison with conventionally obtained direct measurements on plaster casts. Postoperative CBCT acquisitions and plaster casts of 27 patients with adjacent posterior mandibular implants were analyzed in a prospective clinical study. On CBCT images, two observers assessed the inter-implant distances on axial and sagittal views. On plaster casts, the inter-implant distances were measured with a digital caliper. CBCT measurements on axial and sagittal views were, on average, 0.2 mm larger than measurements on plaster casts. Correlation was perfect between measurements of the same inter-implant distance performed by the observers on CBCT images and on plaster casts. When compared with conventionally obtained direct measurements on plaster casts, CBCT views slightly overestimated (mean 0.2 mm) the horizontal mesiodistal measurements between two implants as reference points. CBCT imaging is sufficiently accurate to evaluate mesiodistal distances on axial and sagittal views for dental implant planning in clinical practice.

Impact of multiple firings on fracture load of veneered zirconia restorations.

OBJECTIVES: This investigation evaluated the impact of multiple firings during the veneering process of anterior all-ceramic restorations on the fracture load (FL) of zirconia crowns veneered with different ceramics (ZRT, ZRO, HFZ, STR). METHODS: All-ceramic crowns with anatomically reduced zirconia frameworks were prepared using four different veneering ceramics (N = 192/n = 48 per veneering ceramic). The crowns were fired 2 and 10 times. Half of them were thermocycled (5000 cycles, 5 °C/55 °C, 20s). FL using Voss shear test was measured. Data was analyzed using ANOVA with partial eta squared and post-hoc Scheffé-test as well as t-test and Weibull analysis. RESULTS: Regarding FL, greatest differences were among the number of firings (p<0.001, ηp2 = 0.369). FL was not influenced by the interaction of both number of firings and aging level (p = 0.231) and the interaction of number of firings and veneering ceramic (p = 0.222). Differences were found comparing FL values of ZRT and STR (p<0.001) and of HFZ and STR (p<0.001). No differences occurred among the veneering ceramics after 2 (p = 0.430) and after 10 firings (p = 0.057) in respect to initial FL. For all initially tested veneering ceramics, FL showed higher values after 10 firings (p≤0.001-0.014). When aged, ZRO, HFZ, and STR also provided higher FL values after 10 firings (p≤0.001). For ZRT, FL values differed between initial and aged testing after 2 firings (p = 0.001) with aged specimens providing higher FL values. After 10 firings, none of the veneering ceramics showed differences regarding FL values between initial and aged testing. Weibull modulus was higher for ZRT specimens after 10 firings when tested initially (m = 10.1) and for aged ZRT specimens after 2 firings (m = 11.1). Failures occurred either with chipping of the veneer or total fracture. SIGNIFICANCE: Veneered zirconia restorations tested presented higher FL after 10 firings compared to 2 firings. Aging via thermocycling showed a positive effect on the FL.

Impact of multiple firings on thermal properties and bond strength of veneered zirconia restorations.

OBJECTIVES: This investigation evaluated the impact of multiple firings during the veneering process of all-ceramic restorations on the thermal properties and bond strength between veneering ceramics and zirconia. METHODS: For the measurements of the coefficient of thermal expansion (CTE) prismatic specimens of four different veneering ceramics (ZRT/ZRO/HFZ/STR; N = 40/n = 10 per veneering ceramic) and rod-shaped zirconia specimens (N = 2) were produced. 2 specimens of each veneering ceramic were fired 2, 4, 6, 8, and 10 times simulating dentine-firing. Measurements were performed in a dilatometer and glass transition temperature (Tg) was determined graphically. To analyze bond strength (BS), crack initiation test specimens were prepared using the same veneering ceramics and zirconia (N = 600/n = 150 per veneering ceramic). 30 specimens of each veneering ceramic were fired 2, 4, 6, 8, and 10 times. Half of them were thermocycled (5000 cycles, 5 °C/55 °C, 20s). The crack initiation test was conducted in a universal testing machine. Data was analyzed using ANOVA with partial eta squared statistics and post-hoc Scheffé test as well as Pearson correlation test. RESULTS: CTE was mostly affected by the choice of veneering ceramic (p < 0.001/ηp2 = 0.983). For the leucite-free ceramic, the CTE values were in same value range (p = 0.171) along the number of firings. Tg was not influenced by the number of firings. The highest effect on BS showed veneering ceramics (p < 0.001/ηp2 = 0.055) followed by the number of firings (p = 0.011/ηp2 = 0.023). The global difference in BS was lower for 10 firings compared to 2 firings (p = 0.048). Highest BS were measured for the leucite-free veneering ceramic (ZRT). Artificial aging by thermocycling showed no impact on BS (p = 0.755). Correlations were found for HFZ between the BS and the CTE (r = -0.651/p = 0.021). A correlation between CTE and Tg was observed (r = 0.303/p = 0.029). SIGNIFICANCE: Thermal stability seemed to be more predictable for leucite-free veneering ceramics with superior BS. All BS results exceeded the minimum clinical requirements.

Bending moment of implants restored with CAD/CAM polymer-based restoration materials with or without a titanium base before and after artificial aging.

OBJECTIVES: To test and compare two types of implant systems restored with four monolithic polymer-based materials with regard to their bending moments (BM) before and after aging. METHODS: A total of 192 tissue-level implants (TRI Dental Implants) differing in the presence (TiB, Octa line, n = 96) or absence (NTiB, Matrix line, n = 96) of a titanium base were restored with mandibular right first molar crowns manufactured from composite (CC), polymer-infiltrated ceramic (VE), PMMA (PM) and a 3D printed resin (ND) (n = 24). Half of the specimens (n = 12) were loaded for 1,200,000 cycles (50 N, 1.3 Hz, TC: 5/55 °C, 6000×) and examined for failures. Fracture load was measured according to ISO standard 14801, BM was calculated, and fracture types were examined. Data were analyzed using parametric statistics (p < 0.05). RESULTS: No failures were observed after 600,000 cycles. After 1,200,000 cycles, wear traces were recorded in all groups except PM, VE and CC on TiB implants. In group CC on NTiB implants, three specimens were rated zero in BM testing as they showed fracture of the screw. Regarding BM, TiB implants exhibited higher values than NTiB implants with aged CC (p = 0.023), aged PM (p < 0.001), initial PM (p = 0.011) and initial VE (p < 0.001). No differences occurred among the implant types with initial CC, initial ND, aged ND and aged VE. With regard to initial BM values, NTiB implants showed higher values for ND and CC compared with PM and VE (p < 0.001). No differences in initial BM values were found for the tested materials on TiB implants (p > 0.116). When aged, restoration material had no impact on the BM values of NTiB implants (p ≥ 0.233). Aged TiB implants showed higher values in combination with CC than with ND (p = 0.001). PM and VE showed similar values as ND and CC. Artificial aging led to a decrease of BM within PM, CC and ND on NTiB implants and ND on TiB implants. The majority of failures after testing were characterized by crown fractures in two to four pieces. Fractures in more pieces with smaller fragments occurred primarily for ND. SIGNIFICANCE: The use of NTiB implants with the polymer-based materials tested can only be recommended for clinical use as interim prostheses. CC seems to show a positive effect on the BM. Clinical research investigating the in vivo behavior is necessary to confirm these findings.

A new implant system with directly screwed supra-constructions: Impact of restoration material and artificial aging on the bending moment.

PURPOSE: To investigate the bending moment of implants restored with a directly screwed single-unit fixed dental prosthesis (FDP) compared to implants restored with an FDP polymerized to a titanium base before and after thermomechanical aging. MATERIALS AND METHODS: A total of 240 implants (120 with and 120 without a titanium base) were restored with FDPs manufactured from conventionally sintered 3Y-TZP, 5Y-TZP, 4Y-TZP, and CoCrMo, as well as high-speed sintered 4Y-TZP. Half of the specimens per subgroup were aged using chewing simulation combined with thermocycling (1,200,000 cycles at 50 N; 6,000 cycles at 5°C to 55°C). Initial and aged fracture load were measured. The bending moment was calculated and subjected to statistical analysis (Kolmogorov-Smirnov test, one-way ANOVA followed by post hoc Scheffé, t, and chi-square tests; P < .05). Failure types were analyzed. RESULTS: Implants without a titanium base showed higher bending moments for all initially tested zirconia groups compared to implants with a titanium base. The highest initial values were observed for 4Y-TZP FDPs regardless of implant type. High-speed sintered FDPs demonstrated higher initial bending moments compared to conventionally sintered FDPs. Artificial aging led to a decrease of the bending moment in most of the subgroups. After aging, no differences were found within the restoration materials, sintering protocols, or implant types. Implant deformation occurred mainly with directly screwed FDPs, whereas FDP mobility was predominantly observed among implants with a titanium base. FDP fractures were mainly observed for 5Y-TZP. CONCLUSION: Both implant types exhibited similar values after aging. Thus, implants without a titanium base seem to show equally sufficient stability for clinical applications with all tested materials.

Fatigue resistance of monolithic strength-gradient zirconia materials.

PURPOSE: Evaluation of the effect of three different dynamic fatigue protocols on the fracture resistance of two monolithic strength-gradient zirconia materials. MATERIALS AND METHODS: A total of 240 specimens (3 × 4 × 45 mm) was milled from two different layers (incisal and middle) of two types of strength-gradient zirconia blanks (IPS e. max ZirCAD MT Multi A2 vs. IPS e. max ZirCAD Prime A2), resulting in 60 specimens per material and layer group (IPS e. max ZirCAD MT Multi A2: incisal (MI), middle (MM); IPS e. max ZirCAD Prime A2: incisal (PI), middle (PM)). Each group was divided into one static (n = 15) and three dynamic fatigue protocols (N = 45, n = 15): i. 50 N increase every 5000 cycles ii. Increase by 5% of static fracture load every 5000 cycles iii. 10 N increase every 1000 cycles until facture. All specimens were loaded until facture in CeraTest 2 k. Kaplan-Meier, Log-Rank and Chi-squared-test as well as Weibull statistics were performed. A fractographic analysis was performed. The specimens were classified according to the number of crack origins and evaluated using the Ciba-Geigy table. RESULTS: With regard to the fracture load, in the static loading MI and PI showed a higher fracture load and in dynamic fatigue protocol 2 PI showed a lower fracture load. The number of cycles until fracture only differed within three groups: MM and MI survived a higher number of cycles in dynamic fatigue protocol 2; PI survived a higher number of cycles in dynamic fatigue protocol 2 than in protocol 1. Within dynamic fatigue protocols, PM resisted the highest number of cycles in protocol 1 and 3 and MI in protocol 2. Comparing groups, Weibull modulus differed only within the static loading, with PI showing lower values than MM and MI. Within the material groups, MI showed higher values in static loading than in dynamic fatigue protocol 1 and 2, and PI showed higher values in the dynamic fatigue protocol 3 than in static loading. With regard to fracture patterns, no differences were found between the groups. CONCLUSIONS: Dynamic fatigue protocols provide clinically relevant information on the long-term stability and reliability of monolithic strength-gradient zirconia materials. However, no definitive instructions for dynamic testing can be provided from this investigation.

Effect of Cleaning Protocol on Bond Strength between Resin Composite Cement and Three Different CAD/CAM Materials.

The present investigation tested the effect of the cleaning method on the tensile bond strength (TBS) between one resin composite cement (RCC) and three different computer aided design/computer aided manufacturing (CAD/CAM) materials, namely zirconia, lithium disilicate ceramic and resin composite. Ninety specimens were prepared from each CAD/CAM material (N = 270). The specimens were pre-treated respectively, divided into five subgroups and subjected to five different cleaning protocols, namely i. 37% phosphoric acid, ii. ethanol, iii. phosphoric acid + ethanol, iv. cleaning paste, v. distilled water. After cleaning, the specimens were either conditioned using a universal primer or a universal adhesive and bonded using a dual-curing RCC. After thermo-cycling (20,000x at 5 °C/55 °C), TBS and fracture patterns were evaluated. The data was analyzed using 1- and 2-way Analysis of Variance (ANOVA) with post-hoc Scheffé and partial eta-squared (ƞP²), Kruskal-Wallis, Mann-Whitney U and Chi2 tests (p < 0.05). The CAD/CAM material showed an impact on the BS while the cleaning protocol did not affect the results. Zirconia obtained the highest BS, followed by lithium-disilicate-ceramic. Resin composite resulted in the overall lowest BS. For most fracture patterns, the cohesive type occurred. All tested cleaning protocols resulted in same BS values within one CAD/CAM material indicating that the impact of the cleaning method for the restorative material seems to play a subordinate role in obtaining durable bond strength to resin composite cement. Further, it indicates that the recommended bonding protocols are well adjusted to the respective materials and might be able to compensate the impact of not accurately performed cleaning protocols.

Novel Collagen Matrix to Increase Tissue Thickness Simultaneous with Guided Bone Regeneration and Implant Placement in Esthetic Implant Sites: A Feasibility Study.

The purpose of this case series was to assess safety and feasibility of a novel resorbable collagen matrix (CMX) to enhance tissue thickness simultaneous with implant placement and guided bone regeneration (GBR) in esthetic sites over an 8-week healing period. Soft tissue thickness at implant sites and adjacent teeth was monitored with an ultrasonic device. Overall tissue contour changes were assessed by sequential digital surface model superimpositions. Periodontal parameters and patient-related outcomes revealed no significant changes. Combining a novel CMX and GBR revealed a significant soft tissue thickness increase of 1.56 mm at implant sites after 8 weeks, with no significant decrease between 4 and 8 weeks. The overall tissue contour increase was most significant at a distance of 5 mm from the mucosal margin, corresponding to a tissue increase at the implant shoulder area. No effect was observed at adjacent teeth after 8 weeks.

Short Dental Implants Retaining Two-Implant Mandibular Overdentures in Very Old, Dependent Patients: Radiologic and Clinical Observation Up to 5 Years.

PURPOSE: To describe the survival rate and peri-implant bone loss in very old patients dependent for their activities of daily living (ADL), treated with mandibular two-implant overdentures (IODs) in the context of a previously reported randomized controlled trial. MATERIALS AND METHODS: A total of 19 patients received two interforaminal Straumann implants (Regular Neck, 4.1 mm diameter, 8 mm length) that were subsequently loaded with Locator attachments, transforming their preexisting inferior conventional denture into an IOD. The primary outcome measures were implant survival rate and radiographically assessed peri-implant bone loss. Secondary outcome measures included peri-implant probing depth and Plaque Index scores, as well as implant mobility. Nutritional state (body mass index and blood markers) and cognitive state (Mini-Mental State Examination) were also analyzed. RESULTS: The patient cohort comprised eight men and 11 women with a mean age of 85.7 ± 6.6 years. The implant survival rate up to 5 years was 94.7%, with one early and one late implant failure. The mean loss of peri-implant bone height was 0.17 mm per year (95% confidence interval: 0.09 to 0.24; P < .001). Peri-implant probing depth and Plaque Index scores were low and stable during the first 2 years, and thereafter increased continuously. Correlation analysis suggests that a reduced cognitive function and nutritional state are not a particular risk factor for accelerated peri-implant bone loss. CONCLUSION: The high implant survival and acceptable peri-implant health suggest that neither age nor dependency for the ADLs is a contraindication for the placement of implants. Nevertheless, close monitoring of the patients concerning a potential further functional decline precluding denture management and performing oral hygiene measures is advised.

Long-term outcomes of dental implants with a titanium plasma-sprayed surface: a 20-year prospective case series study in partially edentulous patients.

BACKGROUND: Long-term studies of ≥10 years are important milestones to get a better understanding of potential factors causing implant failures or complications. PURPOSE: The present study investigated the long-term outcomes of titanium dental implants with a rough, microporous surface (titanium plasma sprayed [TPS]) and the associated biologic and technical complications in partially edentulous patients with fixed dental prostheses over a 20-year follow-up period. MATERIALS AND METHODS: Sixty-seven patients, who received 95 implants in the 1980s, were examined with well-established clinical and radiographic parameters. Based on these findings, each implant was classified as either successful, surviving, or failed. RESULTS: Ten implants in nine patients were lost during the observation period, resulting in an implant survival rate of 89.5%. Radiographically, 92% of the implants exhibited crestal bone loss below 1 mm between the 1- and 20-year follow-up examinations. Only 8% yielded peri-implant bone loss of >1 mm and none exhibited severe bone loss of more than 1.8 mm. During the observation period, 19 implants (20%) experienced a biologic complication with suppuration. Of these 19 implants, 13 implants (13.7%) had been treated and were successfully maintained over the 20-year follow-up period. Therefore, the 20-year implant success rate was 75.8 or 89.5% depending on the different success criteria. Technical complications were observed in 32%. CONCLUSION: The present study is the first to report satisfactory success rates after 20 years of function of dental implants with a TPS surface in partially edentulous patients.