Inflammatory Response to Wear Particles: Comparisons Between Zirconia and Titanium In Vitro.

PURPOSE: To compare the inflammatory responses of peripheral blood mononuclear cells (PBMCs) subjected to titanium (Ti) and/or zirconia (Zr) particles while growing on Ti or Zr discs. MATERIALS AND METHODS: In total, 240 discs were fabricated at a size of 2 mm in height and 5 mm in diameter. Of the 240 discs, 120 discs were made of Ti (commercially pure [CP] grade 4), and 120 discs were made of Zr (3 mol% yttria-stabilized zirconia polycrystals [3Y-TZP]). The PBMCs were cultured on the two-disc materials, and particles with a size up to 20 mm Ti (99.5% Ti) and 0.1 to 0.2 mm Zr (3Y-TZP) were added to the cultures. The concentration levels of inflammatory cytokines in culture supernatants were measured through Bio-Plex assay (Bio-Rad Laboratories), and light microscopic analysis was performed to detect cell attachment and characterize particle shape and cell-particle interaction. RESULTS: The inflammatory responses of PBMCs were generally higher when cells were cultured on a Ti surface compared to a Zr surface. In addition, higher cytokine levels were seen when cells were cultured in the presence of Ti particles compared to Zr particles when no discs were used. However, there were only significantly increased levels for three cytokines (MCP-1, IFN-γ, and TNF-α) when particles were added to Ti discs. Higher release of neutrophil extracellular traps (NETs) from neutrophils were seen in presence of Zr particles compared to Ti particles. A reduction in cell death was observed in the presence of Zr particles compared to Ti particles and unstimulated control samples. CONCLUSIONS: The type of growth material and presence of particle affects PBMCs in vitro. Cells seeded on Ti discs and together with Ti particles generated higher levels of inflammatory cytokines compared to the Zr counterparts.

Inflammatory Gene Profile and Particle Presence in Peri-Implant Mucosa: a Pilot Study on 9 Patients.

Objectives: The purpose of this pilot study is to compare gene expression in mucosa around dental implants with zirconia abutment to titanium and investigate presence of particles in mucosa samples and on implant heads. Material and Methods: Ten patients with a single implant supported prosthesis connected to zirconia or titanium abutments were invited at the five-year control. A clinical examination and a survey on experience of function and appearance were conducted. A mucosa biopsy taken in close vicinity to the implant were analysed by real-time polymerase chain reaction (qPCR) and presence of particles in a scanning electron microscope/energy-dispersive X-ray spectroscope (SEM/EDX). Cytological smear samples were collected and analysed through inductively coupled plasma mass spectrometry (ICP-MS) to investigate presence of particles on implant heads. Results: In total, 9 patients participated in the study, five with titanium abutments and four with zirconia abutments. All patients were satisfied with function and aesthetics. Titanium and iron particles were detected in mucosa biopsies. The ICP - MS analysis demonstrated presence of zirconia and titanium. Several proinflammatory genes were upregulated in the zirconia abutment group. Conclusions: Around zirconia abutments a slight increase in proinflammatory response and amount of wear particles was seen as compared to titanium. Wear particles of titanium were present in all soft tissue samples, however zirconia particles only in the samples from implants heads/mucosa with zirconia abutments.

Cobalt chromium alloys in fixed prosthodontics: Investigations of mechanical properties and microstructure.

STATEMENT OF PROBLEM: Cobalt chromium (Co-Cr) alloys possess beneficial mechanical properties because alloys, even in thin sections, can resist high mastication forces and exhibit an acceptable bond to the surface porcelain layer. Traditional manufacturing techniques of Co-Cr alloys such as casting have been replaced with newer fabrication techniques, such as milling, laser melting, and presintered milling. Despite scarce documentation, these new manufacturing techniques are being used to fabricate dental and implant constructions. PURPOSE: This in vitro study investigates the hardness, yield strength, elastic modulus, and microstructure of the most commonly used Co-Cr alloys for fixed prosthodontics based on manufacturing technique. In addition, this study investigates the effect of heat treatment on the mechanical properties and microstructure of these materials. MATERIAL AND METHODS: Five Co-Cr alloys were included (dumbbell and rectangular shaped) based on four manufacturing techniques: cast, milled, laser melted, and presintered milled. Commercially pure titanium grade 4 and titanium-6 aluminum-4 vanadium ELI (extra low interstitial) were included for comparison, and yield strength and elongation after fracture were evaluated. The specimens were tested for hardness using the Vickers test and for elastic modulus using a nondestructive impulse excitation technique. The microstructure of selected specimens was analyzed using focused ion beam-scanning electron microscopy (FIB-SEM) and energy dispersive X-ray spectroscopy (EDS). RESULTS: The mechanical properties depend on the manufacturing technique used; the laser-melted and presintered Co-Cr specimens demonstrated the highest mechanical properties, followed by the milled and cast groups. Both the laser-melted and the presintered milled Co-Cr specimens showed smaller grain size compared with the cast and milled Co-Cr specimens. The titanium-6 aluminum-4 vanadium ELI demonstrated higher hardness and yield strength compared to commercially pure titanium grade 4. No major differences were observed for the selected materials regarding the mechanical properties and microstructural appearance after heat treatment. CONCLUSIONS: The laser melting and presintered milling techniques produced higher mechanical properties compared with the cast and milled Co-Cr. These findings were confirmed through microstructural analysis with respect to the grain size, precipitation, and number of pores.

Long-term performance of implants with moderately rough anodized surface supporting single-tooth restorations: A retrospective analysis with an up to 15-year follow-up.

OBJECTIVES: This retrospective study aimed to evaluate long-term clinical and radiologic performance of anodized surface implants supporting single implant restorations. MATERIALS AND METHODS: Patients who received at least one anodized surface implant for a single-tooth restoration between 2003 and 2004 in the Brånemark clinic (Göteborg, Sweden) were included in the study. The assessed outcomes included implant survival, biological and technical complications, as well as marginal bone levels (MBL) based on radiographs. Baseline data on patient demographics, implant placement, and surgery details were also collected. The cumulative survival rate (CSR) was calculated using the Kaplan-Meier survival analysis. RESULTS: The study included 97 patients with 129 implants. Mean patient age at the time of implant placement was 31.7 ± 16.4 years. All implants were placed in a two-stage approach with delayed loading. The last follow-up visit was on average 13.4 ± 4.8 years after implant insertion. Three implants failed, yielding the implant-level 15-year CSR of 97.4%. Majority of the implants had no biological (70.5%) nor technical (81.4%) complications. The mean MBL was -1.0 ± 0.7 mm (n = 101) at prosthetic placement and -1.8 ± 1.0 mm (n = 80) at the last follow-up, while the mean marginal bone loss (MBL) from prosthetic placement to last follow-up was 0.6 ± 1.1 mm (n = 65). CONCLUSIONS: Moderately rough anodized implants have shown favorable long-term outcomessingle-tooth indication, with high survival and a low rate of technical complications. Furthermore, long-term studies are needed to present longitudinal data on peri-implantitis.

Chewing side preference and laterality in patients treated with unilateral posterior implant-supported fixed partial prostheses.

BACKGROUND: It is not clear to what extent chewing is improved by unilateral oral rehabilitation with implant-supported fixed partial prostheses (ISFPPs). OBJECTIVES: This study aimed to investigate whether patients treated with unilateral ISFPPs in the maxilla use their prostheses during mastication to the same extent as they used their contralateral natural teeth. A further aim was to investigate whether there is a correlation between preferred chewing side and laterality. METHODS: Chewing side preference was assessed in 15 participants treated with unilateral ISFPPs in the maxilla. The first, second, third, fifth and tenth chewing cycles were assessed, and the test was repeated 10 times. All participants also answered a questionnaire about their chewing side preference. RESULTS: Most of the participants presented bilateral chewing, but two (13%) chewed only on the ISFPP. There was no statistically significant association between the objectively assessed chewing side and dental status (natural teeth or ISFPPs) during any of the recorded chewing cycles (p > .1). There were statistically significant correlations between both the subjectively reported usually preferred chewing side and the subjective chewing side preference during the test and the objectively assessed chewing side for the first three chewing cycles (p < .01). No correlation was found between handedness and the objectively assessed chewing side. CONCLUSION: In the present study, most participants chewed bilaterally, and chewing was performed both on the ISFPP and on the natural teeth. No correlation was found between the preferred chewing side, objectively or subjectively determined and laterality.

Implant-Supported Single Crowns with Titanium or Zirconia Abutments: A Retrospective Up-to-5-year Follow-up Study.

PURPOSE: To compare the clinical outcomes of single implants with titanium (Ti) or zirconia (Zr) abutments after up to 5 years in function. MATERIALS AND METHODS: This study was a retrospective analysis on single implants with screw-retained abutments (Zr or Ti) covered with porcelain veneer placed between 2011 and 2013 at one referral specialist clinic. Clinical data from patient records were collected from 132 patients and 174 implants. Technical complications such as fractures, chipping, and abutment screw loosening were registered. Radiographs were analyzed comparing both annual bone loss and accumulated bone loss at 5 years. In 57 patients with 85 implants, the values of accumulated bone loss at 5 years were compared to baseline. RESULTS: Technical complications occurred in 16 (9%) of the implants, most often during the first year. The following complications were found: fracture of the abutment (n = 1); loosening of the abutment screws (n = 5); and chipping of the porcelain veneer (n = 11). Ti abutments had more complications than Zr abutments (79%). Of all the implants, 45% had an annual bone loss ranging between 0.05 and 2.15 mm, and 59% had an accumulated bone loss at 5 years ranging between 0.05 and 4.25 mm. Zr abutments had a statistically significantly higher amount of yearly and accumulated bone loss at 5 years. CONCLUSION: Abutment material affected marginal bone loss. The Zr group displayed statistically more bone loss both yearly and after 5 years compared to the Ti group. Technical complications were not affected by abutment material but were affected by age of the patient.

A retrospective clinical study of fixed tooth- and implant-supported prostheses in titanium and cobalt-chromium-ceramic: 5-9-year follow-up.

OBJECTIVES: The aim of this retrospective study was to evaluate the clinical outcome of fixed tooth- and implant-supported protheses manufactured in porcelain veneered cobalt-chromium (CoCr) or titanium with a follow-up period of 5-9 years. MATERIALS AND METHODS: This study included 63 patients with a total of 86 fixed dental protheses (FDPs) (53 implant-supported and 33 tooth-supported). In total, 67 were short-span FDPs (3-5 units) and 19 were long-span FDPs (6-12 units). The FDPs were evaluated using a modified version of the California Dental Association (CDA). RESULTS: The binary regression analysis indicated that neither CoCr nor titanium had a statistically significant effect on the odds of success or survival of either tooth- or implant-supported FDPs. However, the success of FDPs was negatively affected by greater FDP length and general tooth wear. The survival of FDPs was negatively affected by increased FDP longevity. CONCLUSIONS: This study found no statistically significant effect on the odds of success and survival outcomes for any combination of tooth-supported, implant-supported, porcelain-veneered CoCr, or porcelain-veneered titanium FDPs. As the number of FDPs was limited, the results should be interpreted with caution. CLINICAL RELEVANCE: This study shows that the choice between CoCr porcelain and titanium porcelain in fixed protheses did not have a statistically significant effect on the outcome.

Could Age at Surgery Be Associated with Early Mortality After Implant Surgery? A Retrospective Study of 3,877 Edentulous Patients.

PURPOSE: Knowledge of the early mortality patterns in edentulous implant patients is limited. This study aimed to report patient mortality within the first year after surgery and compare the cause of death with preexisting conditions reported before surgery. MATERIALS AND METHODS: In this retrospective cohort study, data from the Swedish National Death Register on patients, consecutively treated in the edentulous arch between 1986 and 2013, were compared with information from the patient files regarding the preexisting health conditions of the deceased patients. One-year survival rates were calculated and compared with expected mortality in a Swedish reference population based on three age groups: young (< 45 years of age), middle-aged (45 to 64 years of age), and old patients (> 64 years of age). Proportions of mortality between study groups and reference populations were tested by means of a log-rank test, and agreement between diagnoses before surgery and cause of death was tested by means of kappa test. RESULTS: Altogether, 3,877 patients were included, of whom 60 patients died within 1 year after implant surgery (1.5%). The expected mortality in the Swedish reference population was 2.1% (P < .05). Mortality was higher for middle-aged (P = .02) but lower for old patients (P = .0001) compared with the Swedish reference populations. Eight of the deceased patients (13%) had no preexisting conditions, while 48 patients reported a health diagnosis before implant surgery. The most common of these were related to the circulatory system (ICD 10-I), which was the cause of death for 30 patients. A "none to slight agreement" between presurgical diagnoses and cause of death was observed in the population (kappa: 0.152). CONCLUSION: Edentulous implant patients presented overall lower mortality than expected in the general population during the first year after surgery. However, middle-aged patients showed a higher proportion of deceased patients compared with control people of the same age. Cardiovascular diseases were the cause of death in 50% of the group, and the agreement between presurgical and cause of death diagnoses was poor.

Comparison of porcelain veneer fracture in implant-supported fixed full-arch prostheses with a framework of either titanium, cobalt-chromium, or zirconia: An in vitro study.

OBJECTIVES: The aim of this study was to compare porcelain veneer strength on screw-retained implant-supported fixed full-arch prostheses with a framework of either milled titanium (Ti), cobalt-chromium (CoCr), and yttria-stabilized zirconia (Y-TZP) in an in vitro loading model. MATERIALS AND METHODS: Fifteen screw-retained maxillary implant-supported full-arch prostheses (FDP), five each of Ti, CoCr, and Y-TZP frameworks with porcelain veneers were included. All FDPs were subjected to thermocycling before loading until fracture of the veneer. The load was applied at the distal fossa of the occlusal area of the pontic replacing 24. Fracture loads were analyzed, and the fracture quality was assessed. Statistical analysis on the fracture load was performed using Kruskal-Wallis test. The statistical significance was set at p < .05. RESULTS: There was no statistical significance found between the groups regarding fracture load. The highest and lowest load was seen within the CoCr FDP, varying between 340 and 1484 N. Different types of fracture appearances were seen. The Y-TZP FDPs had a higher number of fractures locally in the loaded area while CoCr and Ti more often showed cracks in the anterior region, at a distance from the loaded area. CONCLUSIONS: Within the limitations of this study, the conclusion was that framework material may affect the fracture behavior of maxillary full-arch bridges; however, there were no differences in veneer fracture strength when frameworks of Ti, CoCr, or Y-TZP were compared.

Wear particle release at the interface of dental implant components: Effects of different material combinations. An in vitro study.

OBJECTIVES: Particle generation from implant components caused by frictional wear affect the surrounding peri-implant tissues. The objective of this study was to evaluate the effect of combining implant and abutment materials on wear and particle release in a dynamical loading setup. METHODS: A customized dynamical loading machine was used to subject two implant materials (Titanium and Titanium- Zirconium alloy) paired with two different abutment materials (Titanium and Zirconia) to a cyclic loading set of 240.000 cycles (simulating 1 year of clinical use). The implant and abutment complex was immersed in corrosive liquid to collect particle debris and measure the release of corroded ions. Scanning electron microscopy was used to analyze signs of wear on the components after testing and evaluate the size and composition of particle debris. RESULTS: Wear signs were evident in all material couplings. Particle debris was found on top, inside the implants, and on the abutment heads. The particle size ranged between 0.6 and 16.9 µm, with larger particles composed of Ti. Smaller-sized particles were found in the container liquid ranging from 0.253 to 1.7 µm compared to inside the implants ranging from 3.25 to 95.3 µm. Larger particles were found inside Tizr implants compared to Ti implants. Low levels of ions released due to corrosion were found when measuring content in surrounding liquid. SIGNIFICANCE: Particle generation is evident when subjecting dental implant and abutment couplings in a dynamic loading setup. Internally connected implants hinder the release of larger particles to surrounding container liquid.

Mortality in Edentulous Patients: A Registry-Based Cohort Study in Sweden Comparing 8463 Patients Treated with Removable Dentures or Implant-Supported Dental Prostheses.

OBJECTIVES: The purpose of this study was to investigate if edentulism is associated with all-cause mortality. The aims were to analyze the association between age, socioeconomic factors, and mortality in edentulous patients treated with either removable dentures or implant-supported prostheses. METHODS: All patients who became edentulous according to the Swedish Social Insurance Agency (SSIA) between 2009 and 2013 (N = 8463) were analyzed regarding prosthetic treatment, age, gender, and socioeconomic status. The patients were divided into two groups, depending on whether they were treated with dental implants (implant group; IG) or with conventional removable dentures (denture group; DG). Data on mortality for all included individuals were obtained from the Swedish National Cause of Death Register and compared to a reference population. Cumulative survival rates were calculated, and a multivariable regression analysis for the included variables was performed. RESULTS: Between 2009 and 2018, 2192 of the patients (25.9%) were treated with implant-supported dental prostheses (IG) and 6271 patients (74.1%) were treated with removable dentures without support of dental implants (DG). Altogether 2526 patients (30%) died until December 31, 2019, and the overall mortality was significantly higher for the DG compared to the IG during follow-up (p < 0.001). Younger edentulous patients (≤59 years) presented a higher mortality than the reference population, while implant patients over 79 years of age demonstrated a lower mortality. The final results from the multivariable logistic analysis showed that lower equalized disposable income (EDI) and the choice of conventional removable dentures are the most important factors for increased patient mortality (p < 0.001). CONCLUSIONS: Edentulous patients have an overall higher mortality compared to a reference population. Low socioeconomic status increases all-cause mortality. Individuals treated with dental implants show statistically significant lower 10-year mortality compared to patients treated with conventional removable dentures, regardless of socioeconomic status.

Patient factors related to early implant failures in the edentulous jaw: A large retrospective case-control study.

BACKGROUND: Dental implants provide anchorage for dental prostheses to restore functions for individuals with edentulous jaws. During the healing phase, proper osseointegration is required to prevent early implant failure. More knowledge is needed regarding factors related to early failure of dental implants. PURPOSE: The aim of the present study was to identify possible risk factors for early implant failure, with respect to anamnestic and clinical parameters. MATERIALS AND METHODS: All patients with edentulous jaws with early implant failure (n = 408) from one referral clinic were compared with a matched control group (n = 408) with no implant failure. Early implant failure was identified during the first year of prosthetic function. Matching was performed on age, gender, year of surgery, type of jaw, and type of implant surface. In addition, data on anamnestic and clinical parameters were collected. The data were analyzed with a multivariable logistic regression model using early implant failure as the binary outcome. RESULTS: Five anamnestic factors were statistically significant with respect to higher probability for early implant failure: systemic disease, allergies in general, food allergies, smoking, and intake of analgesic medication. Four clinical conditions (i.e., implants in the opposing jaw, low primary stability, reduced bone volume, and healing complications) were also related to higher probability for early implant failure. CONCLUSIONS: This study identified nine factors associated with early implant failure, several related to patient's general health. Further investigations are needed to fully understand the causality between the obtained variables and early implant failure.

Effect of airborne-particle abrasion and polishing on novel translucent zirconias: Surface morphology, phase transformation and insights into bonding.

PURPOSE: The purpose this study was to investigate the effect of Kern´s air-borne particle abrasion protocol (KAPA) and polishing on two translucent zirconias (4Y, 5Y-zirconias) compared to a traditional zirconia (3Y-zirconia). METHODS: Two different surface treatments were analysed by X-ray diffraction (XRD) and interferometry 1) KAPA (0.1 MPa, 50 µm alumina, 10-12 mm distance, 15 sec and 30 sec and cleaning in ultrasound using isopropyl alcohol 99%) and 2) Clinical-delivery polishing paste (Zircon Brite, Dental Ventures, USA). Shear-bond strength tests (SBS's) were performed with a highly polished and virtually flat surface in combination with a 10-MDP based cement and a surface modified by KAPA in combination with zinc phosphate cement. The SBS was expressed in terms of MPa. RESULTS: The mean values for monoclinic content were 13 wt%, 7 wt% and 2 wt% for 3Y-, 4Y- and 5Y-zirconias respectively, no differences were found between 15 and 30 seconds. Polishing did not result in phase transformation to monoclinic phase in any of the zirconias. The rhombohedral phase was identified in all types of zirconias regardless of surface treatment. Shear-bond strength tests showed 5 MPa for polished/10-MDP based cement and 3 MPa for KAPA/ Zinc phosphate. Statistically significant differences were found between the two different surface treatments but not between the types of zirconias. CONCLUSIONS: KAPA for 15 sec seems to be equal to 30 sec regarding morphology and phase transformation. Sole micro-retention appears not to be fully responsible for the bonding phenomena of 10-MDP and zirconia that underwent KAPA.

Inflammatory Response to Cobalt-Chromium Alloys Fabricated With Different Techniques.

OBJECTIVES: To explore the in vitro cytokine expression of human peripheral blood mononuclear cells exposed to cobalt-chromium alloys, manufactured with different techniques, in comparison with commercially pure titanium grade 4 and titanium alloy grade 23. MATERIAL AND METHODS: Peripheral blood mononuclear cells (PBMC) were collected from 10 healthy blood donors and exposed to machine-ground coin-shaped: (a) cobalt-chromium (Co-Cr) specimens (n = 5) manufactured by four techniques, i.e. cast, milled, laser melted and presintered milled; (b) commercially pure titanium grade 4; and (c) titanium alloy grade 23. The cells were cultured for 4, 24 and 72 hours followed by investigations of pro- and anti-inflammatory cytokine release using Bio-Plex Pro™. RESULTS: In general, the PBMC produced significantly more cytokines when exposed to the cast and presintered milled Co-Cr materials compared to laser melted, milled Co-Cr and titanium materials. CONCLUSIONS: Within the limitation of the present study, it may be suggested that cast and presintered milled cobalt-chromium alloys provoke a stronger inflammatory response compared to milled and laser melted cobalt-chromium alloys and titanium materials.

Cobalt-chromium alloys fabricated with four different techniques: Ion release, toxicity of released elements and surface roughness.

OBJECTIVE: To investigate the metal ion release, surface roughness and cytoxicity for Co-Cr alloys produced by different manufacturing techniques before and after heat treatment. In addition, to evaluate if the combination of materials affects the ion release. METHODS: Five Co-Cr alloys were included, based on four manufacturing techniques. Commercially pure titanium, CpTi grade 4 and a titanium alloy were included for comparison. The ion release tests involved both Inductive Coupled Plasma Optical Emission Spectrometry and Inductive Coupled Plasma Mass Spectrometry analyses. The surface analysis was conducted with optical interferometry. Cells were indirectly exposed to the materials and cell viability was evaluated with the MTT (3-(4.5-dimethylthiazol-2-yl)-2.5-diphenyltetrazolium bromide) method. RESULTS: All alloys showed a decrease of the total ion release when CpTi grade 4 was present. The total ion release decreased over time for all specimens and the highest ion release was observed from the cast and milled Co-Cr alloy in acidic conditions. The cast and laser-melted Co-Cr alloy and the titanium alloy became rougher after heat treatment. All materials were within the limits of cell viability according to standards. SIGNIFICANCE: The ion release from Co-Cr alloys is influenced by the combination of materials, pH and time. Surface roughness is influenced by heat treatment. Furthermore, both ion release and surface roughness are influenced by the manufacturing technique and the alloy type. The clinical implication needs to be further investigated.

Biofilm formation on polyetheretherketone and titanium surfaces.

Objective: Polyetheretherketone (PEEK) is a polymer used in devices in orthopedic and dental rehabilitation. The aim of this in vitro study was to compare biofilm formation by a range of important oral bacterial species on PEEK, blasted PEEK, commercially pure titanium (cp-Ti), and titanium-6 aluminium-4 vanadium (Ti6Al4V). Material and methods: Coin-shaped samples were manufactured, and the surfaces were characterized using optical interferometry, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and contact angle measurements. Bacterial species of Streptococcus sanguinis, Streptococcus oralis, Enterococcus faecalis, and Streptococcus gordonii were cultured on the four material surfaces for varying amounts of time. Biofilms were quantified following staining with crystal violet. Results: Roughness and contact angle results showed blasted PEEK > PEEK > cp-Ti = Ti6Al4V. There was increased biofilm formation on blasted PEEK by S. sanguinis, S. oralis, and S. gordonii, whereas the bacterial adhesion was similar on PEEK, cp-Ti, and Ti6Al4V. The bacterial growth of E. faecalis was significantly higher on cp-Ti compared with the other three groups. Conclusion: The results, taking into consideration the biofilm formation, suggest that PEEK should perform as well as cp-Ti or TiAl6V4 when used as a dental restorative material.

Infraposition of anterior maxillary implant-supported single-tooth restorations in adolescent and adult patients-A prospective follow-up study up to 6 years.

BACKGROUND: In the maxillary incisor area infraposition of implant restorations can be an esthetic problem. PURPOSE: The aim was to analyze the prevalence of infraposition of single-tooth implant restorations in the anterior maxilla in adolescent and adult patients. MATERIAL AND METHODS: The study comprised of 31 patients, 18 women and 13 men, with 39 restorations and with a mean and median age of 23.8 and 18.8 years, range 17.8 to 52.8 years, at the time of implant crown connection. The mean and median time in function for the restorations was 4.5 and 4.3 years respectively with a range of 3.3 to 6.6 years. RESULTS: Twenty restorations 51%, showed no signs of infraposition. A slight infraposition (<0.5 mm) was seen in 36% of the restorations. Only in one patient, the observed infraposition of the implant crown was more than 1 mm. We found no significant difference of the observed level of vertical infraposition, Score A (0 mm) and Score B (<0.5 mm), in subjects where the restoration was placed before the age of 20 years compared to the older patients. There were no significant differences in changes of the vertical infraposition when comparing different parameters such as age, gender, jaw relation (Angle-classes I-III), overbite/overjet, occlusal contact on the implant crown, bone augmentation before or at implant installation or if orthodontic treatment of the neighboring teeth had been made before or after the implant installation. CONCLUSIONS: In the present study, there was a significant yet low correlation between the observed vertical infraposition of the single-tooth implant restoration and the subject's evaluation of the esthetics of the restoration (VAS). Fifty-one percent of the implant-supported crowns, showed no signs of vertical infraposition. A slight infraposition (< 0.5 mm) was however seen in 36% of the restorations. Only one crown showed a vertical infraposition of more than 1 mm.

Chemical Bonding to Novel Translucent Zirconias: A Mechanical and Molecular Investigation.

PURPOSE: To investigate direct bonding of a 10-MDP-based cement to two novel translucent yttria-stabilized tetragonal zirconia polycrystal ceramics (4Y-TZP, 5Y-TZP) and observe the influence of thermocycling on this bonding. MATERIALS AND METHODS: Powders of presintered and isostatically pressed 5Y-TZP, 4Y-TZP and 3Y-TZP were mixed with a 10-MDP-based cement (Panavia F 2.0), then stored in deionized water for 48 h at 37°C or thermocycled 10,000 times. Raman spectroscopy and Fourier-transform infrared spectroscopy were used to assess the presence of a functional group (PO32-) that could indicate bonding before and after thermocycling. X-ray photoelectron spectroscopy was used to identify the presence of the suspected Zr-O-P bond in the same specimens. A shear-bond strength (SBS) test was conducted based on ISO 29022:2013. RESULTS: Marked peaks assigned to the asymmetric vibrations of the PO32- functional group were observed in both zirconias before and after thermocycling. The binding energy corresponding to Zr-O-P interactions (531.5 eV) was masked by the aluminosilicate in the filler of the cement. Shear bond strengths were approximately 20 MPa after water storage and approximately 6 MPa after thermocycling. No differences were found between the control group and the translucent zirconias. CONCLUSION: Direct bonding of the 10-MDP-based cement to both 4Y-TZP and 5Y-TZP was highly plausible. Both 4Y-TZP and 5Y-TZP may be promising alternatives to glass-ceramic restorations.

Causes of Death in Implant Patients Treated in the Edentulous Jaw: A Comparison between 2098 Deceased Patients and the Swedish National Cause of Death Register.

BACKGROUND: Previous research has reported an association between tooth loss and patient mortality, while the cause of death has not been elucidated. OBJECTIVE: The purpose was to describe and compare the cause of death in implant patients treated consecutively in the edentulous arch with a reference population. METHODS: Altogether, 3902 patients were included between 1986 and 2014. Data on the causes of death for deceased patients were compared to the Swedish National Cause of Death Register for a comparable time period. Standardised mortality ratios (SMRs) were calculated based on gender and age and tested for statistical significance. RESULTS: Most deceased patients (2,098) died from diseases in the circulatory system (CVD; 42%) and from cancers (26%). SMR indicated a generally increased mortality (total group) compared to the reference population during inclusion (P < 0.05; 1986-2014). Patients treated early (1986-1996) showed a lower SMR compared to patients treated later (P < 0.05; 1997-2014) especially related to CVDs. Younger patients (<60 years at surgery) showed an increased mortality due to CVDs when treated late (1997-2014; SMR = 5.4, P < 0.05). Elderly patients (>79 years at surgery) showed a significantly lower mortality in almost all observed causes of death (1986-2014; P < 0.05) with also a significantly lower mortality due to CVDs during the early period (1986-1996; SMR = 0.3, P < 0.05). CONCLUSION: An overall increased mortality was observed for the edentulous implant patient compared to the reference population. Elderly patients (>79 years) showed significantly lower mortality for all causes of death independent of the time period of implant surgery. Younger patients (<60 years) present an increased risk for early mortality related to CVD. SMR for all causes of death increased for patients treated late (1997-2014) as compared to patients treated early (1986-1996).

Fit of 3Y-TZP complete-arch implant-supported fixed dental prostheses before and after porcelain veneering.

STATEMENT OF PROBLEM: To minimize technical complications, implant-supported fixed dental prostheses must fit well. The fit of complete-arch veneered zirconia frameworks has not been fully evaluated. PURPOSE: The purpose of this in vitro study was to evaluate the fit of screw-retained zirconia implant-supported complete-arch maxillary frameworks for fixed dental prostheses before and after porcelain veneering. MATERIAL AND METHODS: Ten stone casts simulating an edentulous maxilla and provided with 6 abutment analogs were produced. For each stone cast, 1 zirconia framework was fabricated by computer-aided design and computer-aided manufacturing. The fit was analyzed by using a coordinate measuring machine in 3 dimensions (x, y, and z axes) using best fit by virtual matching of center point coordinates before and after porcelain veneering. Also, the horizontal distances between implant position pairs P1-P6, P2-P5, and P3-P4 were measured. Furthermore, an optical microscope was used to evaluate vertical fit at the terminal abutments after porcelain veneering. RESULTS: Before the porcelain veneering procedure, the frameworks had a mean horizontal misfit of 27.7 µm in the x-axis and 12.0 µm in the y-axis. In the vertical dimension (z-axis), the mean misfit was 2.4 µm and the mean 3D misfit value was 32.3 µm before veneering. Porcelain veneering increased the mean misfit by 0.2 µm in the horizontal plane (x and y axes), 0.4 µm in the vertical plane, and 0.4 µm in 3D; the difference before and after veneering was not statistically significant (P>.05). The mean ±standard deviation vertical misfit at the terminal abutments was 9.2 ±2.9 µm, optically recorded after porcelain veneering. The measured horizontal distances between implant position pairs P1-P6, P2-P5, and P3-P4 increased to 0.9 µm, 2.0 µm, and 1.9 µm, respectively, after porcelain veneering. The difference for the implant position pair P2-P5 was statistically significant (P<.05). CONCLUSIONS: Screw-retained zirconia implant-supported complete-arch maxillary frameworks for fixed dental prostheses have a fit well within the range of 30 µm in the horizontal plane and 10 µm in the vertical plane. The porcelain veneering procedure did not affect the fit of the frameworks.