Carbonation, Cementation, and Stabilization of Ultramafic Mine Tailings.

Tailings dam failures can cause devastation to the environment, loss of human life, and require expensive remediation. A promising approach for de-risking brucite-bearing ultramafic tailings is in situ cementation via carbon dioxide (CO2) mineralization, which also sequesters this greenhouse gas within carbonate minerals. In cylindrical test experiments, brucite [Mg(OH)2] carbonation was accelerated by coupling organic and inorganic carbon cycling. Waste organics generated CO2 concentrations similar to that of flue gas (up to 19%). The abundance of brucite (2-10 wt %) had the greatest influence on tailings cementation as evidenced by the increase in total inorganic carbon (TIC; +0.17-0.84%). Brucite consumption ranged from 64-84% of its initial abundance and was mainly influenced by water availability. Higher moisture contents (e.g., 80% saturation) and finer grain sizes (e.g., clay-silt) that allowed for a better distribution of water resulted in greater brucite carbonation. Furthermore, pore clogging and surface passivation by Mg-carbonates may have slowed brucite carbonation over the 10 weeks. Unconfined compressive strengths ranged from 0.4-6.9 MPa and would be sufficient in most scenarios to adequately stabilize tailings. Our study demonstrates the potential for stabilizing brucite-bearing mine tailings through in situ cementation while sequestering CO2.

Interproximal contact loss in a retrospective cross-sectional study of 4325 implants: Distribution and incidence and the effect on bone loss and peri-implant soft tissue.

STATEMENT OF PROBLEM: Interproximal contact loss (ICL) is a common finding between implant restorations and teeth, yet few reports have been published on incidence or related complications. PURPOSE: The purpose of this cross-sectional retrospective study was to measure the ICL of 4325 implants, including single and multiple splinted restorations. MATERIAL AND METHODS: Data on 4325 implants were extracted from patient records on ICL, time of follow-up, implant location, and sex of the participant for whom implants were placed in a private practice between 1999 and 2016. Periapical radiographs were used to evaluate the crestal bone level (CBL), whereas peri-implant soft tissues were evaluated with the implant mucosal index (IMI). Measurements (ICL, IMI, and CBL) were evaluated with an average follow-up of 4.5 years (range: 0.25 to 21 years). ICL was assessed in relation to the implant location and sex and grouped by the last clinical recall (1, 2-3, 4-5, 6-7, or 8+ years) to evaluate the effect of time. Data were analyzed by the chi-square test (α=.05). RESULTS: Overall, 17% of implants had ICL, and this significantly increased over time from 11% at 1 year to 29% at ≥8 years (chi-square: 123.8, P<.001). Mandibular implants had more ICL (20%) than maxillary implants (15%) (chi-square: 17.5, P<.001), whereas no difference was found between molar and premolar sites or male and female participants. There was no significant effect of ICL on CBL over time, but there was an increase in inflammation with higher IMI scores at ICL sites. CONCLUSIONS: The incidence of implant ICL was found to be 17%, and ICL was found to increase over time up to 27% at ≥8 years of follow-up. ICL was more common in posterior and mandibular sites. ICL was shown to increase soft tissue inflammation but was not found to affect implant CBLs.

Retrospective Study of 1087 Anodized Implants Placed in Private Practice: Risk Indicators Associated With Implant Failure and Relationship Between Bone Levels and Soft Tissue Health.

INTRODUCTION: To evaluate risk indicators associated with implant failure and relationship between bone levels and soft-tissue health of anodized implants placed in private practice. MATERIAL AND METHODS: Partially or completely edentulous patients who received an anodized implant between 2003 and 2013 were included. Univariate and multivariate analysis was used to identify the relationship between study variables and implant failure. Mean marginal bone level changes (MBLΔ) were assessed using periapical radiographs. Periimplant soft tissue was evaluated using a modified bleeding index (implant mucosal index, IMI). RESULTS: A total of 1087 implants placed in 414 patients were followed for 3.9 ± 2.7 years. The cumulative implant survival rate after 10 years of function was 97.0%. Shorter (P = 0.0068) and maxillary implants (P = 0.0314) were associated with lower implant survival rate. Mean MBL decreased from -0.16 ± 0.43 mm at baseline to -0.53 ± 0.53 mm 8 to 10 years later. Implants with healthier mucosa were associated with less bone loss. CONCLUSIONS: Implants with an anodized surface showed a high long-term survival rate in a daily practice. Longer implants and implants placed in the mandible were associated with greater survival. Immediate loading and tapered design did not affect implant survival. Profuse multipoint bleeding and suppuration on recall were associated with greater bone loss.

Performance of zirconia abutments for implant-supported single-tooth crowns in esthetic areas: a retrospective study up to 12-year follow-up.

OBJECTIVE: The aim of this clinical study was to assess complications, success, and survival rates of zirconia abutments from different implant designs. MATERIAL AND METHODS: Anterior implant-supported single-tooth restorations, after 1-12 years of clinical function, were evaluated. One hundred and fifty-eight zirconia implant abutments placed in 141 patients were evaluated. Mechanical complications were observed, such as presence or absence of abutment fractures and loss of retention. In addition, the peri-implant parameters were observed. Statistical analysis was performed using Fisher's exact tests, and bone level was analyzed using the nonparametric Mann-Whitney U-test for non-normally distributed data. RESULTS: Sixteen restorations exhibited different complications. However, no significant difference was observed between the standard and platform switching. The standard platforms exhibited higher marginal bone loss than platform switching design followed up to 5 years. Platform switching has a potentially higher risk of fracture in some designs. In our study, one standard platform as well as two-platform switch designs seem to withstand fracture in the anterior area, regardless of the implant width. Survival and success rates were 93.8% and 81.2% (up to >7 years ≤12), respectively, for standard platform; and 90 and 84% (up to >2 years ≤5), respectively, for platform switching. CONCLUSIONS: In general, standard platform implants restored with zirconia abutments were successful for the longest periods of observation and are a viable treatment alternative in anterior areas. Some of the studied designs of platform switching implants with zirconia abutments performed well for up to 5 years.

Retrospective cohort study of 4591 Straumann implants in private practice setting, with up to 10-year follow-up. Part 1: multivariate survival analysis.

OBJECTIVE: The purpose of this retrospective, noninterventional, open cohort study is to report on the long-term survival of dental implants, in private practice representing the daily realities of implant treatment. The data are analyzed to discern statistical relationships between explanatory variables and implant failure. MATERIALS AND METHODS: A total of 4591 Straumann implants were placed in 2060 patients between 1999 and 2012. Patients were evaluated after 2-3 months, 1, 3, 5, and 7 years and, in some cases, up to 10 years. The cumulative survival rate (CSR) was calculated according to the life table method and illustrated with Kaplan-Meier survival curves. Univariate analysis was performed to investigate the association between study variables and time to implant-failure. Variables with P -value < 0.15 were further selected for a multivariate analysis. Statistical methods which take into account the fact that some patients have more than one implant (therefore, dependency between implants within mouth) had been applied. RESULTS: At the implant level, the cumulative survival rates at 3, 5, and 7 years were 99.3%, 99.0%, and 98.4%, respectively, and at the patient level, they were 98.6%, 97.7%, and 95.9%, respectively. After adjustment to possible confounders, the multivariate analysis identified a relationship between the following risk indicators for implant failure: implant location, length and design, timing of implantation, bone grafting procedures and gender. Tissue-Level implants (n = 3863) had a very high survival rate of 99% at 3 years, which was maintained over the entire study period. Bone-Level implants (n = 600) were as predictable with a survival rate of 99% up to 3 years, while Tapered Effect implants (n = 128) demonstrated a lower survival rate of 95% at 5 years. Short 6-mm implants in the mandibular posterior sites had a high survival rate of 100%, while in maxillary posterior positions a survival rate of only 87% was achieved. Patient factors such as smoking, autoimmune disease, and penicillin allergy were tending to associate with higher failure rates. CONCLUSION: High long-term survival rates were observed for a large cohort of Straumann implants. Tissue- and Bone-Level implants had higher survival rates than Tapered Effect implants, and although short implants faired well in the mandibular posterior sites, they faired less well in the maxillary posterior sites. The study represents private practice insight into large-scale, long-term implant results.

Radiographic bone loss around dental implants: a large-cohort, long-term follow-up revealing prevalence and predictive factors.

OBJECTIVE: This retrospective study analyzed radiographic bone levels of 10,871 dental implants in a cohort of 4,247 patients over a 22-year period. The objectives of the study were to assess and explore risk factors associated with the radiographic bone level of dental implants. METHOD AND MATERIALS: A longitudinal observational cohort study based on data collected from 1995 to 2019 was conducted on implants placed by a single periodontist. Inclusion criteria included both partially and fully edentulous sites. Exclusion criteria were patients who were considered ASA 3 or greater. Information on medical and dental status prior to implant placement such as diabetes and smoking were included in the analysis. Implant factors such as the implant characteristics (length and diameter) and surgical site were recorded. The outcome assessed was the prevalence of bone loss around implants and any associative factors related to the bone loss. RESULTS: Overall, dental implants lost an average of 0.05 ± 0.38 mm of bone 2 to 3 years after placement and 0.21 ± 0.64 mm 8 years after placement. The soft tissue condition was evaluated using the Implant Mucosal Index (IMI), and bone loss around dental implants was significantly higher when bleeding on probing was multi-point and moderate, multi-point and profuse, and when infection with suppuration was recorded. The mean difference in bone level between smokers and nonsmokers was 0.26 mm (P < .01) over a 4-year period. A mean difference of 0.10 mm (P = .04) in bone loss over 4 years was found between those with an autoimmune disease compared to those without. The diameter of the implant and immediate loading of the dental implant did not influence the radiographic bone levels over time. CONCLUSIONS: This large dataset of dental implants highlights predictive risk factors for bone loss around dental implants and the impact these risk factors have on the implant bone level. Consideration of these risk factors by both the dental team and the patient prior to dental implant placement will promote success of the treatment.

Long term clinical performance of 10 871 dental implants with up to 22 years of follow-up: A cohort study in 4247 patients.

BACKGROUND: The present retrospective study was aimed to assess the long-term clinical performance of dental implants in a cohort study of 4247 patients. METHODS: A longitudinal observational cohort study was done on all implants performed by a single periodontist from July 1995 to April 2019. The main outcome variables of this study were implant failure and marginal bone level around implants. RESULTS: The study participants received a total of 10 871 implants with a mean of 2.56 implants per patient. The cohort was followed-up to 22.2 years (mean = 4.5 ± 4.2). Among the 4247 patients of the current study, 140 patients (3.3%) experienced a combined total of 178 implant failures. According to life table analysis, at the implant level the cumulative survival rate at 3, 5, 10, and 15 years was 98.9%, 98.5%, 96.8%, and 94.0%, respectively while at patient level was 97.4%, 96.7%, 92.5%, and 86% at 3, 5, 10, and 15 years. Patients with multiple units were at a greater risk for having an implant failure. Baseline bone level was 0.09 ± 0.28 mm while at 8-10 years the mean bone level was 0.49 ± 0.74 mm. The incidence of peri-implant mucositis at the implant level was 9.4% at 2-3 years, 9.3% at 4-5 years, 12.1% at 6-7 years, and 11.9% at 8-10 years. The incidence of peri-implantitis was 2%, 2.6%, 3.2%, and 7.1% at 2-3, 4-5, 6-7, and 8-10 years, respectively. Cigarette smoking and diabetes mellitus were positively correlated with implant failure. CONCLUSIONS: Though the results are promising and encouraging in terms of survival and bone level over time, it is important to emphasize the potential risk factors and consider them prior to dental implant placement.

Retrospective cohort study of 4,591 dental implants: Analysis of risk indicators for bone loss and prevalence of peri-implant mucositis and peri-implantitis.

BACKGROUND: Due to the risk of peri-implantitis, following dental implant placement, this study aimed to evaluate risk indicators associated with marginal bone loss from a retrospective open cohort study of 4,591 dental implants, placed in private practice, with 5- to 10-year follow-up. Furthermore, the prevalence of mucositis and peri-implantitis among the study cohort was evaluated, comparing strict versus relaxed criteria for bleeding on probing. METHODS: Periapical radiographs were used to evaluate changes in crestal bone level. Peri-implant soft tissue was evaluated using an ordinal mucosal index in comparison with the conventional binary threshold for bleeding (i.e., present or not). Periodontal probing depth was not evaluated. Linear mixed models were used to evaluate bone level over time, and other risk indicators, at the patient and implant level. RESULTS: Risk indicators found to have a significant impact on bone level included: autoimmune disease, heavy smoking, bisphosphonate therapy, implant location, diameter and design, and the presence of a bone defect at site of implantation. The prevalence of mucositis at the implant level was 38.6% versus 14.2% at 6 to 7 years, when using strict versus relaxed criteria, respectively. The prevalence of peri-implantitis after 6 to 7 years was 4.7% and 3.6% when using strict versus relaxed criteria, respectively. CONCLUSIONS: The results of this study identify several risk factors associated with bone loss. Furthermore, the prevalence of mucositis and peri-implantitis was shown to be lower at both the implant and the patient when using strict versus relaxed criteria based on the assessment of oral health surrounding dental implants.

Retrospective Cohort Study of 4,591 Straumann Implants Placed in 2,060 Patients in Private Practice with up to 10-Year Follow-up: The Relationship Between Crestal Bone Level and Soft Tissue Condition.

PURPOSE: The purpose of this report is to describe the crestal bone level (CBL) around implants of various designs, describe the peri-implant soft tissue condition, and evaluate the relationship between the two over time. MATERIALS AND METHODS: This retrospective cohort study reports on 2,060 patients with 4,591 implants evaluated after 3 months; 1, 3, 5, and 7 years; and up to 10 years. Periapical radiographs were used to evaluate changes in CBL. The peri-implant soft tissue was evaluated using a modified Bleeding Index termed the Implant Mucosal Index (IMI) where: 0 = no bleeding; 1 = minimal, single-point bleeding; 2 = moderate, multipoint bleeding; 3 = profuse, multipoint bleeding; and 4 = suppuration. RESULTS: At 3 months, the mean CBL was 0.06 ± 0.22 mm; by 8 to 10 years, it had increased to 0.44 ± 0.81 mm. The median CBL remained stable throughout the study at < 0.1 mm. At 8 to 10 years, 15% of implants exhibited a CBL > 1.02 mm, and 5% exhibited a CBL > 2.28 mm. More than 50% of patients experienced some bleeding, as seen by an IMI ≥ 1 during follow-up. A positive correlation was found between IMI and CBL, as shown by a mean CBL after 4 years of 0.33 mm, 0.71 mm, and 1.52 mm for IMI = 2, 3, and 4, respectively. One exception was between IMI = 0 and IMI = 1, where no significant difference was found and bone loss was minimal. CONCLUSION: Bone loss, as measured by changes in CBL during the first 10 years of implant life spans, was minimal for most implants. Nevertheless, it is not unusual to observe implants with advanced bone loss. The soft tissue condition is a good indicator of bone loss. Time alone and minimal bleeding did not correlate with bone loss, but care should be taken for implants with profuse bleeding or suppuration.

Clinical retrospective study of self-reported penicillin allergy on dental implant failures and infections.

OBJECTIVE: The aim of this retrospective study was to investigate whether self-reported allergy to penicillin may contribute to a higher rate of postsurgical infection and implant failure. METHOD AND MATERIALS: This retrospective, non-interventional, open cohort study reports on implant survival and infection complications of 5,576 implants placed in private practice by one periodontist, and includes 4,132 implants that were followed for at least 1 year. Logistic regression was applied to examine the relationship between self-reported allergy to penicillin and implant survival, while controlling for potential confounders such as smoking, implant site, bone augmentation, loading protocol, immediate implantation, and bone level at baseline. The cumulative survival rate (CSR) was calculated according to the life table method and the Cox proportional hazard model was fitted to data. RESULTS: Out of 5,106 implants placed in patients taking penicillin it was found that 0.8% failed, while 2.1% failed of the 470 implants placed for patients with self-reported allergy to penicillin (P = .002). Odds of failure for implants placed in penicillin-allergic patients were 3.1 times higher than in non-allergic patients. For immediate implant placement, penicillin-allergic patients had a failure rate 10-times higher than the non-allergic cohort. Timing of implant failure occurring within 6 months following implantation was 80% in the penicillin-allergic group versus 54% in the non-allergic group. From the 48 implant sites showing postoperative infection: penicillin-allergic patients had an infection rate of 3.4% (n = 16/470) versus 0.6% in the non-allergic group (n = 32/5,106) (P < .05). CONCLUSION: Self-reported penicillin allergy was associated with a higher rate of infection, and primarily affected early implant failure.

Survival and Success Rates of Dental Implants Placed Using Osteotome Sinus Floor Elevation Without Added Bone Grafting: A Retrospective Study with a Follow-up of up to 10 Years.

This retrospective study with a follow-up period of 4 months to 10 years evaluated survival, success, and complication rates of implants placed using osteotome sinus floor elevation (OSFE) without added bone grafting. A total of 926 implants were placed, including 530 short implants (6 mm to 8.5 mm) and 209 implants in low residual bone height (RBH) (< 5 mm). Bone levels were evaluated at approximately 3 months and at 1, 3, and 5 years, and in some cases up to 10 years after implants were placed. The implant survival rate was 98.3% at the 5-year follow-up. Twelve of the 926 implants failed (6 preprosthetic, 6 postprosthetic). The success rate was 95.4% at a threshold of less than 1 mm of bone loss for combined systems (Straumann; Nobel Biocare). Short implant survival and success rates were statistically comparable to conventional-length implants. Low-RBH implants had a lower but acceptable survival rate of 95.7%. Adverse events were rare, with one case of infection and zero cases of vertigo reported. The findings of this study indicate that implant placement with OSFE without added bone graft is highly successful, even when short implants are used in low RBH.

Trifactorial classification system for osteotome sinus floor elevation based on an observational retrospective analysis of 926 implants followed up to 10 years.

OBJECTIVE: A novel osteotome trifactorial classification system is proposed for transcrestal osteotome-mediated sinus floor elevation (OSFE) sites that includes residual bone height (RBH), sinus floor anatomy (contour), and multiple versus single sites OSFE (tenting). METHOD AND MATERIALS: An analysis of RBH, contour, and tenting was retrospectively applied to a cohort of 926 implants placed using OSFE without added bone graft and followed up to 10 years. RBH was divided into three groups: high (RBH > 6 mm), mid (RBH = 4.1 to 6 mm), and low (RBH = 2 to 4 mm). The sinus "contour" was divided into four groups: flat, concave, angle, and septa. For "tenting", single versus multiple adjacent OSFE sites were compared. RESULTS: The prevalence of flat sinus floors increased as RBH decreased. RBH was a significant predictor of failure with rates as follows: low- RBH = 5.1%, mid-RBH = 1.5%, and high-RBH = 0.4%. Flat sinus floors and single sites as compared to multiple sites had higher observed failure rates but neither achieved statistical significance; however, the power of the study was limited by low numbers of failures. CONCLUSION: The osteotome trifactorial classification system as proposed can assist planning OSFE cases and may allow better comparison of future OSFE studies.

The question-behavior effect: genuine effect or spurious phenomenon? A systematic review of randomized controlled trials with meta-analyses.

OBJECTIVE: Simply answering questions about a specific behavior may change that behavior. This is known as the mere-measurement or question-behavior effect (QBE). Our objective was to synthesize the evidence for the QBE on health-related behaviors. METHOD: Included studies were randomized controlled trials that tested the effect of questionnaires or interviews about health-related behaviors and/or related cognitions compared with a no-measurement control condition or another form of measurement. Subgroup analyses were conducted to identify potential moderators. RESULTS: 41 studies were included assessing a range of health behaviors. Meta-analyses showed a small overall QBE effect (SMD = 0.09; 95% CI [0.04, 0.13]; k = 33). Studies showed moderate heterogeneity, variable risk of bias, and evidence of publication bias. No dose-response relationships were found from studies comparing more with less intensive measurement conditions. There were no significant differences in QBE by behavior, but QBEs for dental flossing, physical activity, and screening attendance were significantly different from 0. Findings were not altered by whether behavior or cognitions were measured, attitudes were or were not measured, studies used questionnaires or interviews, or outcomes were objective or self-reported. CONCLUSIONS: There is some evidence for the QBE on health-related behavior. However, risk of bias within studies and evidence of publication bias indicate that the observed small effect size may be overestimated, especially given that some studies included intervention techniques in addition to providing questionnaires. Preregistered high-quality trials with clear specification of intervention content are needed to confirm if and when measurement leads to behavior change.

Eight-year clinical and radiologic results of maxillary and mandibular implant-retained bar overdentures carried out on oxidized (TiUnite™) replace select implants placed in regenerated bone: a clinical case.

This article describes the clinical and radiologic long-term results of a healthy, nonsmoker women aged 62 at the time of treatment, with severely resorbed edentulous jaws in which bar and clip supported complete dentures were delivered in both jaws and followed for 8 years after prosthesis delivery. The patient had been edentulous in both arches since she was 50 years old. Treatment included the placement of four mandibular implants with maximum spacing anterior to the mandibular nerve, and four maxillary implants anterior to sinus wall without tilting the posterior implants, because of the insufficient bone quantity necessary to angulate implants. Guided bone regeneration was required in the maxilla, due to a bone atrophy that limited the placement of conventional dental implants. After 4 months, a second-stage surgery was performed, and after 1 month of healing time the patient received definitive restorations. Implant survival rate, patient satisfaction, marginal bone maintenance, and soft tissue conditions at the modified titanium surface of the dental implants were evaluated after 8 years of function. A multifactorial approach, clinician-patient relationship, and vigilant maintenance of oral hygiene were needed in order to ensure an optimal treatment and a long-term successful result. Positive results regarding bone maintenance in the long-term perspective, also on regenerated bone, were observed using implants with implant-retained bar overdentures, when adequate levels of oral hygiene and prosthodontic adjustments are maintained.