Soft tissue response and determination of underlying risk drivers for recession and mucositis after AMSJI implantation in the maxilla.

PURPOSE: There are few treatment options for oral rehabilitation in patients with advanced maxillary resorption (Cawood-Howell Class V or more). Patient-specific, 3D-printed titanium subperiosteal implants have been described as a potentially valuable alternative solution. Surgeon and patient mediated functional outcomes have been studied and the results are promising. The surrounding soft tissue health has been much less researched. This study aims to evaluate the soft tissue response to the placement of additively manufactured subperiosteal jaw implants (AMSJI®) in the severely atrophic maxilla and to identify possible risk factors for soft tissue breakdown. MATERIALS AND METHODS: An international multicenter study was conducted and fifteen men (mean age 64.62 years, SD ± 6.75) and twenty-five women (mean age 65.24 years, SD ± 6.77) with advanced maxillary jaw resorption (Cawood-Howell Class V or more) were included in this study. General patient data were collected and all subjects were clinically examined. Inclusion criteria were patients who underwent bilateral AMSJI placement® in the maxilla at least a year before and whose surgeon and themselves agreed to participate in the study before their inclusion. RESULTS: A total of forty patients were enrolled with a mean follow-up period of 917 days (SD ± 306.89 days). Primary stability of the implant was achieved postoperatively in all cases, and all implants were loaded with a final prosthesis. At the time of study, only one patient showed mobility of the bilateral AMSJI (more than 1 mm). Exposure of the framework, due to mucosal recession, was seen in 26 patients (65%) and was mainly in the left (21.43%) and right (18.57%) mid-lateral region. Thin biotype and the presence of mucositis were found to be risk factors (p-value < 0.05). Although not significant, smokers had a nearly seven times (Odds ratio 6.88, p=0.08) more risk of developing a recession compared to nonsmokers. CONCLUSION: Twenty-six (65%) patients presented with a recession in one or (more) of the seven regions after oral rehabilitation with bilateral AMSJI installation. Several risk drivers were evaluated. The collapse of soft tissues around the AMSJI that led to caudal exposure of the arms was correlated with a thin biotype and the presence of mucositis.

Patient Satisfaction and Impact on Oral Health after Maxillary Rehabilitation Using a Personalized Additively Manufactured Subperiosteal Jaw Implant (AMSJI).

Subperiosteal implants (SIs) were first developed by Dahl in 1941 for oral rehabilitation in case of severe jaw atrophy. Over time, this technique was abandoned due to the high success rate of endosseous implants. The emergence of patient-specific implants and modern dentistry allowed a revisitation of this 80-year-old concept resulting in a novel "high-tech" SI implant. This study evaluates the clinical outcomes in forty patients after maxillary rehabilitation with an additively manufactured subperiosteal jaw implant (AMSJI®). The oral health impact profile-14 (OHIP-14) and numerical rating (NRS) scale were used to assess patient satisfaction and evaluate oral health. In total, fifteen men (mean age: 64.62 years, SD ± 6.75 years) and twenty-five women (mean age: 65.24 years, SD ± 6.77 years) were included, with a mean follow-up time of 917 days (SD ± 306.89 days) after AMSJI installation. Patients reported a mean OHIP-14 of 4.20 (SD ± 7.10) and a mean overall satisfaction based on the NRS of 52.25 (SD ± 4.00). Prosthetic rehabilitation was achieved in all patients. AMSJI is a valuable treatment option for patients with extreme jaw atrophy. Patients enjoy treatment benefits resulting in high patient satisfaction rates and impact on oral health.

A 20-year split-mouth comparative study of two screw-shaped titanium implant systems.

PURPOSE: To prospectively assess marginal bone loss and implant survival with Astra Tech (Dentsply Sirona, Charlotte, NC, USA) (group A) and Brånemark (Nobel Biocare, Zurich, Switzerland) (group B) implants in a split-mouth study conducted over a 20-year follow-up period. MATERIALS AND METHODS: A total of 95 implants (n = 50, group A and n = 45, group B) were randomly placed in the left or right side of the maxilla or mandible in 18 patients. Clinical and radiographic examinations were performed, and results were reported at 5, 10, 15 and 20 years after insertion of the prosthesis. RESULTS: Ten patients were followed up for 20 years (n = 26 implants, group A and n = 25 implants, group B). No implant loss or prosthetic failures were observed. After 20 years of follow-up, no significant differences in marginal bone loss were found between both implant groups (P = 0.25). The proportion of marginal bone loss ≥ 0.5 mm was not significantly different between implant types (P > 0.05), and no statistically significant relationships were found between marginal bone loss and time (P ≥ 0.05). More specifically, there was no significant difference in marginal bone level between year 20 and baseline in group A (P = 0.70), whereas a difference of 0.5 to 1.0 mm was found in group B (P = 0.15). CONCLUSIONS: After 20 years of follow-up, marginal bone loss around screw-shaped titanium implants was clinically insignificant. Furthermore, no significant differences in survival and marginal bone loss were found between group A and B implants over the follow-up period.

Radiographic Evaluation of Bone Remodeling after Additively Manufactured Subperiosteal Jaw Implantation (AMSJI) in the Maxilla: A One-Year Follow-Up Study.

Additively manufactured subperiosteal jaw implants (AMSJI) are patient-specific, 3D-printed, titanium implants that provide an alternative solution for patients with severe maxillary bone atrophy. The aim of this study was to evaluate the bony remodeling of the maxillary crest and supporting bone using AMSJI. Fifteen patients with a Cawood-Howell Class V or greater degree of maxillary atrophy were evaluated using (cone beam) computed tomography scans at set intervals: one month (T1) and twelve months (T2) after definitive masticatory loading of bilateral AMSJI implants in the maxilla. The postoperative images were segmented and superimposed on the preoperative images. Fixed evaluation points were determined in advance, and surface comparison was carried out to calculate and visualize the effects of AMSJITM on the surrounding bone. A total mean negative bone remodeling of 0.26 mm (SD 0.65 mm) was seen over six reference points on the crest. Minor bone loss (mean 0.088 mm resorption, SD 0.29 mm) was seen at the supporting bone at the wings and basal frame. We conclude that reconstruction of the severely atrophic maxilla with the AMSJI results in minimal effect on supporting bone. Reduced stress shielding with a biomechanically tuned subperiosteal implant does not induce radiographically significant crestal bone atrophy.

Oral Implant Restorations By Undergraduate Students: An Up To 5-Years Clinical Outcome.

PURPOSE: To clinically evaluate oral implant restorations placed by undergraduate students in the dental clinical curriculum at KU Leuven (Belgium) in terms of function and esthetics. MATERIALS AND METHODS: A retrospective observational cohort study was designed. The esthetic and functional evaluations of implant-supported restorations placed in the framework of the undergraduate implant dentistry clinical training program using White/Pink Esthetic Score (WES/PES) and visual analog scale (VAS) scoring was performed. Furthermore, complications were registered based retrospectively on the patient's medical file. The following research questions were stipulated: (1) How well do implant-supported restorations placed by undergraduate students perform esthetically? and (2) Which complications occurred and how were these managed? RESULTS: Between August 2008 and July 2014 (6 academic terms), 251 implants (Brånemark System Mk III, Nobel Biocare) were placed in 113 patients by 155 students (> 40% of all students enrolled in the training program). Of these implants, 228 were restored in 101 patients by 118 students with varying restoration types. Esthetic scoring of the restorations in 83 of these patients revealed a satisfying mean WES of 8.14 ± 2.09 (out of 10) and PES of 9.56 ± 3.14 (out of 14). Complications were registered in 18.9% of the cases. DISCUSSION: Clinical training in implant dentistry for undergraduates contributes to the development of advanced skills in the dental student's Master education. Overall, patients were satisfied with their implant-supported restorations. Implant and restoration success rates and complication incidence were confirmed by long-term data in the oral implant literature.

Randomized controlled trial comparing immediate loading with conventional loading using cone-anchored implant-supported screw-retained removable prostheses: A 2-year follow-up clinical trial.

STATEMENT OF PROBLEM: Implant-based prosthetic solutions can be time consuming. If implants can be loaded immediately, treatment time can be reduced. PURPOSE: The purpose of this prospective randomized controlled trial was to monitor the survival rate of Ankylos implants, comparing conventional with immediate loading by using abutments with the SynCone concept for screw-retained removable prostheses in the edentulous maxilla. MATERIAL AND METHODS: A total of 90 implants were placed in 15 study participants. The participants were randomly assigned to the immediate or conventional loading treatment group. Radiographic and clinical parameters were recorded at the time of permanent prosthesis installment and at 1- and 2-year follow-up examinations, and participants' satisfaction was measured by using questionnaires before and after prosthesis installation. A linear mixed model was used to measure differences. RESULTS: One implant in the conventional group was lost during abutment placement; hence, 89 implants could be followed for 2 years. Approximately 90% of these implants showed no bone loss or even bone gain at 1 and 2 years follow-up. Mean values for the immediate group were, respectively, 0.09 ±0.35 mm and 0.13 ±0.38 mm and 0.01 ±0.41 mm and -0.06 ±0.32 mm for the conventional method. No significant differences (P=.053) were found in bone level alterations between the groups. For all participants, the mean number of surfaces (4 per implant) with bleeding on probing (BoP) and plaque were 0.76 ±0.81 and 0.16 ±0.42 at 1 year follow-up and 0.44 ±0.66 and 0.02 ±0.15, respectively, at the second-year follow-up. The mean pocket probing depths were 2.05 ±0.54 mm at 1 year and 2.18 ±0.64 mm at 2 years. For both groups, a significant rise in satisfaction and quality of life was observed (P≤.001) at 1 and 2 years compared with pretreatment. CONCLUSIONS: Ankylos implants placed in the edentulous maxilla, immediately or conventionally loaded by a detachable prosthesis, showed favorable bone-level preservation after 2 years of follow-up. No significant differences could be found between the immediate and conventional groups. A significant increase in quality of life was observed for both loading modes.

Effect of high-frequency loading and parathyroid hormone administration on peri-implant bone healing and osseointegration.

The objective of this study is to examine the effect of low-magnitude, high-frequency (LMHF) loading, and anti-osteoporosis medications such as parathyroid hormone (PTH) and bisphosphonates on peri-implant bone healing in an osteoporosis model, and to assess their combined effects on these processes. Thirteen-week-old ovariectomized rats (n = 44) were divided into three groups: PTH, alendronate, and saline. After 3 weeks of drug administration, titanium implants were inserted into the tibiae. Each group was subdivided into two groups: with or without LMHF loading via whole-body vibration (50 Hz at 0.5 g, 15 min per day, 5 days per week). Rats were killed 4 weeks following implantation. Removal torque test, micro-CT analyses (relative gray (RG) value, water = 0, and implant = 100), and histomorphometric analyses (bone-to-implant contact (BIC) and peri-implant bone formation (bone volume/tissue volume (BV/TV))) were performed. Removal torque values and BIC were significantly differed by loading and drug administration (ANOVA). Post hoc analysis showed that PTH-treated groups were significantly higher than the other drug-treated groups. BV/TV was significantly enhanced by PTH administration. In cortical bone, RG values were significantly increased by loading. In trabecular bone, however, RG values were significantly increased by PTH administration. These findings suggest that LMHF loading and PTH can act locally and additively on the bone healing process, improving the condition of implant osseointegration.

A robust methodology for the quantitative assessment of the rat jawbone microstructure.

Micro-computed tomography can be applied for the assessment of the micro-architectural characteristics of the cortical and trabecular bones in either physiological or disease conditions. However, reports often lack a detailed description of the methodological steps used to analyse these images, such as the volumes of interest, the algorithms used for image filtration, the approach used for image segmentation, and the bone parameters quantified, thereby making it difficult to compare or reproduce the studies. This study addresses this critical need and aims to provide standardized assessment and consistent parameter reporting related to quantitative jawbone image analysis. Various regions of the rat jawbones were screened for their potential for standardized micro-computed tomography analysis. Furthermore, the volumes of interest that were anticipated to be most susceptible to bone structural changes in response to experimental interventions were defined. In the mandible, two volumes of interest were selected, namely, the condyle and the trabecular bone surrounding the three molars. In the maxilla, the maxillary tuberosity region and the inter-radicular septum of the second molar were considered as volumes of interest. The presented protocol provides a standardized and reproducible methodology for the analysis of relevant jawbone volumes of interest and is intended to ensure global, accurate, and consistent reporting of its morphometry. Furthermore, the proposed methodology has potential, as a variety of rodent animal models would benefit from its implementation.

Controlled Clinical Trial on the Outcome of Glass Fiber Composite Cores Versus Wrought Posts and Cast Cores for the Restoration of Endodontically Treated Teeth: A 5-Year Follow-up Study.

PURPOSE: The aim of this study was to compare the 5-year outcomes of glass fiber composite with cast posts and cores for the restoration of endodontically treated teeth. MATERIALS AND METHODS: A total of 143 patients in need of 203 full ceramic restorations on endodontically treated teeth were included. After primary stratification based on the need for post or no post, teeth were randomly allotted to test group 1 (prefabricated glass fiber posts), 2 (custom-made glass fiber posts), or 3 (composite cores without posts). The control group was treated with gold alloy-based wrought posts and cast cores. Success (original present) and survival (present after intervention) probability lifetime curves, corrected for clustering, were drawn over the entire data set. RESULTS: The mean follow-up time was 5.8 years (range: 0.5 to 7.2 years). At 5 years, the success and survival probabilities were 85.2% and 91.5%, respectively. Lifetime curves did not show any significant differences between the test and control groups for success (P = .85) or survival (P = .57). Moreover, no significant differences for success or survival could be found among the four groups (the three test groups and the control group). CONCLUSION: After 5 years of follow-up, cast gold and composite post-and-core systems on teeth with ceramic full restorations provided with a ferrule performed equally well.

Residual compressive surface stress increases the bending strength of dental zirconia.

OBJECTIVE: To assess the influence of surface treatment and thermal annealing on the four-point bending strength of two ground dental zirconia grades. METHODS: Fully-sintered zirconia specimens (4.0×3.0×45.0mm3) of Y-TZP zirconia (LAVA Plus, 3M ESPE) and Y-TZP/Al2O3 zirconia (ZirTough, Kuraray Noritake) were subjected to four surface treatments: (1) 'GROUND': all surfaces were ground with a diamond-coated grinding wheel on a grinding machine; (2) 'GROUND+HEAT': (1) followed by annealing at 1100°C for 30min; (3) 'GROUND+Al2O3 SANDBLASTED': (1) followed by sandblasting using Al2O3; (4) 'GROUND+CoJet SANDBLASTED': (1) followed by tribochemical silica (CoJet) sandblasting. Micro-Raman spectroscopy was used to assess the zirconia-phase composition and potentially induced residual stress. The four-point bending strength was measured using a universal material-testing machine. RESULTS: Weibull analysis revealed a substantially higher Weibull modulus and slightly higher characteristic strength for ZirTough (Kuraray Noritake) than for LAVA Plus (3M ESPE). For both zirconia grades, the 'GROUND' zirconia had the lowest Weibull modulus in combination with a high characteristic strength. Sandblasting hardly changed the bending strength but substantially increased the Weibull modulus of the ground zirconia, whereas a thermal treatment increased the Weibull modulus of both zirconia grades but resulted in a significantly lower bending strength. Micro-Raman analysis revealed a higher residual compressive surface stress that correlated with an increased bending strength. SIGNIFICANCE: Residual compressive surface stress increased the bending strength of dental zirconia. Thermal annealing substantially reduced the bending strength but increased the consistency (reliability) of 'GROUND' zirconia.

Strength, toughness and aging stability of highly-translucent Y-TZP ceramics for dental restorations.

OBJECTIVE: The aim was to evaluate the optical properties, mechanical properties and aging stability of yttria-stabilized zirconia with different compositions, highlighting the influence of the alumina addition, Y2O3 content and La2O3 doping on the translucency. METHODS: Five different Y-TZP zirconia powders (3 commercially available and 2 experimentally modified) were sintered under the same conditions and characterized by X-ray diffraction with Rietveld analysis and scanning electron microscopy (SEM). Translucency (n=6/group) was measured with a color meter, allowing to calculate the translucency parameter (TP) and the contrast ratio (CR). Mechanical properties were appraised with four-point bending strength (n=10), single edge V-notched beam (SEVNB) fracture toughness (n=8) and Vickers hardness (n=10). The aging stability was evaluated by measuring the tetragonal to monoclinic transformation (n=3) after accelerated hydrothermal aging in steam at 134°C, and the transformation curves were fitted by the Mehl-Avrami-Johnson (MAJ) equation. Data were analyzed by one-way ANOVA, followed by Tukey's HSD test (α=0.05). RESULTS: Lowering the alumina content below 0.25wt.% avoided the formation of alumina particles and therefore increased the translucency of 3Y-TZP ceramics, but the hydrothermal aging stability was reduced. A higher yttria content (5mol%) introduced about 50% cubic zirconia phase and gave rise to the most translucent and aging-resistant Y-TZP ceramics, but the fracture toughness and strength were considerably sacrificed. 0.2mol% La2O3 doping of 3Y-TZP tailored the grain boundary chemistry and significantly improved the aging resistance and translucency. Although the translucency improvement by La2O3 doping was less effective than for introducing a substantial amount of cubic zirconia, this strategy was able to maintain the mechanical properties of typical 3Y-TZP ceramics. SIGNIFICANCE: Three different approaches were compared to improve the translucency of 3Y-TZP ceramics.

Influence of Light Irradiation Through Zirconia on the Degree of Conversion of Composite Cements.

PURPOSE: To assess the light irradiance (LI) delivered by two light-curing units and to measure the degree of conversion (DC) of three composite cements and one flowable composite when cured through zirconia or ceramic-veneered zirconia plates with different thicknesses. MATERIALS AND METHODS: Three dual-curing composite cements (Clearfil Esthetic Cement, Panavia F2.0, G-CEM LinkAce) and one light-curing flowable composite (G-aenial Universal Flo) were investigated. Nine different kinds of zirconia plates were prepared from three zirconia grades (YSZ: Aadva and KATANA; Ce-TZP/Al2O3: NANOZR) in three different thicknesses (0.5- and 1.5-mm-thick zirconia, and 0.5-mm-thick zirconia veneered with a 1.0-mm-thick veneering ceramic). Portions of the mixed composite cements and the flowable composite were placed on a light spectrometer to measure LI while being light cured through the zirconia plates for 40 s using two light-curing units (n = 5). After light curing, micro-Raman spectra of the composite films were acquired to determine DC at 5 and 10 min, 1 and 24 h, and at 1 week. RESULTS: The zirconia grade and the thickness of the zirconia/veneered zirconia plates significantly decreased LI. Increased LI did not increase DC. Only the Ce-TZP/Al2O3 (NANOZR) zirconia was too opaque to allow sufficient light transmission and resulted in significantly lower DC. CONCLUSION: Although zirconia-based restorations attenuate the LI of light-curing units, the composite cements and the flowable composite could be light cured through the YSZ zirconia. LI is too low through Ce-TZP/Al2O3 zirconia, necessitating the use of self-/dual-curing composite cements.

Accuracy and patient-centered outcome variables in guided implant surgery: a RCT comparing immediate with delayed loading.

AIM: To assess the accuracy and patient-centered outcome of a novel guided surgery system for placing implants in an edentulous maxilla. MATERIAL AND METHODS: Fifteen consecutive patients with sufficient bone to place six implants in the maxilla were randomly assigned to the immediate loading (with delivery of the final prosthesis within 24 h) or the delayed loading treatment group. Accuracy was assessed by matching the planning CT with a postoperative CBCT. Patient-centered outcome measures were the Dutch version of the McGill Pain Questionnaire (MPQ-DLV), the health-related quality of life instrument (HRQOL), visual analog scales (VAS), the duration of the procedure, and the analgesic doses taken each day. RESULTS: A mean deviation was found at the entry point of 0.9 mm (range: 0.1-4.5, median 0.8) and of 1.2 mm (range: 0.2-4.9, median 1.1) at the apex, and an angular deviation of 2.7° (range: 0.0-6.6°, median 2.3) was observed. The mean vertical deviation was 0.5 mm (range: 0.0-3.2, median 0.4), and in a horizontal direction, this was 0.7 mm (range: 0.1-3.1, median 0.6). The mean deviation in mesio-distal direction was 0.5 mm (range: 0.0-2.3, median 0.4) and in bucco-lingual direction 0.5 mm ± 0.4 (range: 0.0-2.2, median 0.3). No statistical differences could be shown between treatment groups on pain response (MPQ-DLV), treatment perception (VAS), number or kind of pain killers, or for the HRQOLI instrument. CONCLUSION: The accuracy of a novel CT-based guide is comparable to the accuracy data of other systems. Within the limitations of this study, no difference could be found in patient-centered outcome variables after immediate or delayed loading.

Digital versus conventional implant impressions for edentulous patients: accuracy outcomes.

PURPOSE: To compare the accuracy of digital and conventional impression techniques for completely edentulous patients and to determine the effect of different variables on the accuracy outcomes. MATERIALS AND METHODS: A stone cast of an edentulous mandible with five implants was fabricated to serve as master cast (control) for both implant- and abutment-level impressions. Digital impressions (n = 10) were taken with an intraoral optical scanner (TRIOS, 3shape, Denmark) after connecting polymer scan bodies. For the conventional polyether impressions of the master cast, a splinted and a non-splinted technique were used for implant-level and abutment-level impressions (4 cast groups, n = 10 each). Master casts and conventional impression casts were digitized with an extraoral high-resolution scanner (IScan D103i, Imetric, Courgenay, Switzerland) to obtain digital volumes. Standard tessellation language (STL) datasets from the five groups of digital and conventional impressions were superimposed with the STL dataset from the master cast to assess the 3D (global) deviations. To compare the master cast with digital and conventional impressions at the implant level, analysis of variance (ANOVA) and Scheffe's post hoc test was used, while Wilcoxon's rank-sum test was used for testing the difference between abutment-level conventional impressions. RESULTS: Significant 3D deviations (P < 0.001) were found between Group II (non-splinted, implant level) and control. No significant differences were found between Groups I (splinted, implant level), III (digital, implant level), IV (splinted, abutment level), and V (non-splinted, abutment level) compared with the control. Implant angulation up to 15° did not affect the 3D accuracy of implant impressions (P > 0.001). CONCLUSION: Digital implant impressions are as accurate as conventional implant impressions. The splinted, implant-level impression technique is more accurate than the non-splinted one for completely edentulous patients, whereas there was no difference in the accuracy at the abutment level. The implant angulation up to 15° did not affect the accuracy of implant impressions.

Bonding Effectiveness to Differently Sandblasted Dental Zirconia.

PURPOSE: To evaluate the effect of different mechanical pre-treatments on the bond durability to dental zirconia. MATERIALS AND METHODS: Fully sintered IPS e.max ZirCAD (Ivoclar Vivadent) blocks were randomly assigned to one of 4 groups: (1) kept as-sintered (control), (2) sandblasted with 50-µm Al2O3(Danville), or tribochemically silica sandblasted using (3) CoJet (3M ESPE) and (4) SilJet (Danville). The zirconia specimens were additionally pre-treated chemically using a 10-MDP/silane ceramic primer (Clearfil Ceramic Primer, Kuraray Noritake). Two identically pre-treated zirconia blocks were bonded together using resin-composite cement (RelyX Ultimate, 3M ESPE). The specimens were trimmed at the interface to a cylindrical hourglass shape and stored in distilled water (7 days, 37°C), after which they were randomly tested as is or subjected to additional mechanical aging involving cyclic tensile stress (10 N, 10 Hz, 10,000 cycles). Subsequently, the microtensile bond strength was determined and SEM fractographic analysis performed. RESULTS: Weibull analysis revealed the highest Weibull scale and shape parameters when zirconia was tribochemically silica sandblasted using either CoJet or SilJet. The Weibull shape parameter of Al2O3-sandblasted zirconia was significantly reduced upon mechanical aging, but not when zirconia was tribochemically silica sandblasted. CONCLUSION: The mechanical surface pre-treatment of zirconia using tribochemical silica sandblasting (CoJet, SilJet) resulted in the most favorable bond durability of a resin-composite cement (RelyX Ultimate) to dental zirconia before and after aging.

A 5-Year Prospective Study on Cone-Anchored Implants in the Edentulous Maxilla.

PURPOSE: To investigate dentist- as well as patient-centered outcomes of the implant-supported cone-anchored removable prosthesis in the edentulous maxilla over 5 years. MATERIALS AND METHODS: Ten patients, edentulous in the maxilla, received six Ti implants after which they were delayed loaded through a cone-anchored removable prosthesis. Clinical parameters such as plaque and bleeding indices, PTV, implant success, marginal bone loss, device and prosthesis complications, and patient satisfaction (visual analogue scale) were collected at follow-up visits scheduled 1, 3, 6, 12, 24, 36, and 60 months postprosthesis delivery. RESULTS: After at least 5 years of follow-up (mean: 63.7 months), 53/59 implants were rated successful, while two of 59 failed and one implant was kept sleeping. Mean marginal bone loss from prosthesis delivery until 1, 3, and 5 years, respectively, was; 0.15 (SD: 0.87), 0.36 (SD: 1.07), and 0.60 mm (SD: 1.12). The mean Periotest® values at baseline and 5 years did not differ significantly. After 1 year, a significant improvement in patient satisfaction was recorded compared with the old denture, and this remained stable over the 5-year period. CONCLUSIONS: Cone-anchored removable dental prostheses retained by secondary splinted implants offer a safe alternative for patients with an edentulous maxilla in need of more comfort. Dentist- as well as patient-centered outcomes compete with reports using other prosthetic anchoring devices. Larger replica studies are encouraged to further validate this concept.

Highly-translucent, strong and aging-resistant 3Y-TZP ceramics for dental restoration by grain boundary segregation.

Latest trends in dental restorative ceramics involve the development of full-contour 3Y-TZP ceramics which can avoid chipping of veneering porcelains. Among the challenges are the low translucency and the hydrothermal stability of 3Y-TZP ceramics. In this work, different trivalent oxides (Al2O3, Sc2O3, Nd2O3 and La2O3) were selected to dope 3Y-TZP ceramics. Results show that dopant segregation was a key factor to design hydrothermally stable and high-translucent 3Y-TZP ceramics and the cation dopant radius could be used as a controlling parameter. A large trivalent dopant, oversized as compared to Zr(4+), exhibiting strong segregation at the ZrO2 grain boundary was preferred. The introduction of 0.2 mol% La2O3 in conventional 0.1-0.25 wt.% Al2O3-doped 3Y-TZP resulted in an excellent combination of high translucency and superior hydrothermal stability, while retaining excellent mechanical properties.

Aging resistance of surface-treated dental zirconia.

UNLABELLED: The influence of surface treatment on the low-temperature degradation (LTD) of tetragonal zirconia polycrystalline (TZP) is still unclear. OBJECTIVES: The effect of surface treatments on the LTD behavior of zirconia was investigated. METHODS: Fully-sintered specimens of seven commercial dental zirconia (Aadva, GC; In-CeramYZ, VITA; IPS e.max ZirCAD, Ivoclar Vivadent; LAVA Frame and LAVA Plus, 3M ESPE; NANOZR, Panasonic; ZirTough, Kuraray Noritake) were provided by the manufacturers with specimen dimensions of approximately 10mm×5mm×3mm. For each zirconia grade, samples were kept 'as sintered' (untreated) or were subjected to one of the three surface treatments: rough polished, sandblasted with Al2O3, tribochemical silica sandblasted (n=3/group). The tetragonal to monoclinic transformation was evaluated by X-ray diffraction at several intervals during LTD testing up to 40h in steam in an autoclave (134°C, 2bar). RESULTS: The five yttria-stabilized TZP (Y-TZP: Aadva, In-CeramYZ, IPS e.max ZirCAD, LAVA Frame, LAVA Plus) zirconia showed a similar trend in LTD behavior. The Al2O3 sandblasted zirconia showed the highest monoclinic volume fraction. The as sintered (untreated) zirconia degraded faster than the surface-treated zirconia. Although the surface-treated ceria-stabilized TZP/alumina (Ce-TZP/Al2O3: NANOZR) zirconia had a higher initial monoclinic volume fraction compared to the Y-TZP zirconia, it showed a stronger aging resistance. The as sintered (untreated) Y-TZP/alumina (Y-TZP/Al2O3: ZirTough) zirconia showed a strong aging resistance, whereas the surface-treated Y-TZP/Al2O3 zirconia degraded slightly. SIGNIFICANCE: Surface treatment improved the aging resistance of Y-TZP zirconia. Surface treatment did not affect the LTD behavior of Ce-TZP/Al2O3 zirconia, while surface treatment decreased the aging resistance of Y-TZP/Al2O3 zirconia.

Dental Implant Macro-Design Features Can Impact the Dynamics of Osseointegration.

PURPOSE: The purpose of this study was to compare the clinical performance of two dental implant types possessing a different macro-design in the in vivo pig model. MATERIALS AND METHODS: Titanium Aadva(TM) implants (GC, Tokyo, Japan) were compared with OsseoSpeed(TM) implants (Astra, Mölndal, Sweden), with the Aadva implant displaying significant larger inter-thread dimensions than the OsseoSpeed implant. Implants were installed in the parietal bone of 12 domestic pigs and left for healing for either 1 or 3 months. Implant osseointegration was evaluated by quantitative histology (bone volume relative to the tissue volume [BV/TV]; bone-to-implant contact [BIC]) for distinct implant regions (collar, body, total implant length) with specific implant thread features. The Wilcoxon-Mann-Whitney nonparametric test with α = 0.05 was performed. RESULTS: An inferior amount of bone enveloping the Aadva implant compared with the OsseoSpeed implant was observed, in particular at the implant body part with its considerable inter-thread gaps (p < .05). Concomitantly, the Aadva macro-design negatively affected the amount of bone in direct contact with the implant for this specific implant part (p < .05), and resulted in an overall impaired implant osseointegration at the initial healing stage (total implant length; 1-month healing; p < .05). CONCLUSION: Although the Aadva implant displayed a clinically acceptable level of osseointegration, the findings demonstrate that implant macro-design features can impact the dynamics of implant osseointegration. Consideration of specific implant macro-design features should be made relative to the biological and mechanical microenvironment.

Stimulation of titanium implant osseointegration through high-frequency vibration loading is enhanced when applied at high acceleration.

Low-magnitude high-frequency loading, applied by means of whole body vibration (WBV), affects the bone. Deconstructing a WBV loading stimulus into its constituent elements and investigating the effects of frequency and acceleration individually on bone tissue kinetics around titanium implants were aimed for in this study. A titanium implant was inserted in the tibia of 120 rats. The rats were divided into 1 control group (no loading) and 5 test groups with low (L), medium (M) or high (H) frequency ranges and accelerations [12-30 Hz at 0.3×g (F(L)A(H)); 70-90 Hz at 0.075×g (F(M)A(M)); 70-90 Hz at 0.3×g (F(M)A(H)); 130-150 Hz at 0.043×g (F(H)A(L)); 130-150 Hz at 0.3×g (F H A H)]. WBV was applied for 1 or 4 weeks. Implant osseointegration was evaluated by quantitative histology (bone-to-implant contact (BIC) and peri-implant bone formation (BV/TV)). A 2-way ANOVA (duration of experimental period; loading mode) with α = 0.05 was performed. BIC significantly increased over time and under load (p < 0.0001). The highest BICs were found for loading regimes at high acceleration with medium or high frequency (F(M)A(H) and F(H)A(H)), and significantly differing from F(L)A(H) and F(M)A(M) (p < 0.02 and p < 0.005 respectively). BV/TV significantly decreased over time (p < 0.0001). Loading led to a site-specific BV/TV increase (p < 0.001). The highest BV/TV responses were found for F(M)A(H) and F(H)A(H), significantly differing from F(M)A(M) (p < 0.005). The findings reveal the potential of high-frequency vibration loading to accelerate and enhance implant osseointegration, in particular when applied at high acceleration. Such mechanical signals hold great, though untapped, potential to be used as non-pharmacologic treatment for improving implant osseointegration in compromised bone.