Opaque Layer Firing Temperature and Aging Effect on the Flexural Strength of Ceramic Fused to Cobalt‐Chromium Alloy

Purpose: To evaluate the effect of the opaque layer firing temperature and mechanical and thermal cycling on the flexural strength of a ceramic fused to commercial cobalt‐chromium alloy (Co‐Cr). The hypotheses were that higher opaque layer temperatures increase the metal/ceramic bond strength and that aging reduces the bond strength. Materials and Methods: Metallic frameworks (25 × 3 × 0.5 mm³; ISO 9693) (N = 60) were cast in Co‐Cr and airborne‐particle abraded (Al₂O₃: 150 μm) at the central area of the frameworks (8 × 3 mm²) and divided into three groups (N = 20), according to the opaque layer firing temperature: Gr1 (control)—900°C; Gr2—950°C; Gr3—1000°C. The opaque ceramic (Opaque, Vita Zahnfabrick, Bad Säckingen, Germany) was applied, and the glass ceramic (Vita Omega 900, Vita Zahnfabrick) was fired onto it (thickness: 1 mm). While half the specimens from each group were randomly tested without aging (water storage: 37°C/24 hours), the other half were mechanically loaded (20,000 cycles; 50 N load; distilled water at 37°C) and thermocycled (3000 cycles; 5°C to 55°C, dwell time: 30 seconds). After the flexural strength test, failure types were noted. The data were analyzed using 2‐way ANOVA and Tukey's test (α= 0.05). Results: Gr2 (19.41 ± 5.5 N) and Gr3 (20.6 ± 5 N) presented higher values than Gr1 (13.3 ± 1.6 N) (p= 0.001). Mechanical and thermal cycling did not significantly influence the mean flexural strength values (p > 0.05). Increasing the opaque layer firing temperature improved the flexural bond strength values (p < 0.05). The hypotheses were partially accepted. Conclusion: Increasing of the opaque layer firing temperature improved the flexural bond strength between ceramic fused to Co‐Cr alloy.     

A Comparative Study of the Effect of Four Consecutive Firing Cycles on the Marginal Fit of All: Ceramic Crown System and Metal Ceramic Crown System

The marginal fit of new all ceramic crown system. To know the marginal adaptability of new all ceramic systems. Finesse all ceramic system and traditional metal ceramic system total 15 samples of all ceramic (test group) and 15 samples of metal ceramic crown system (control group) were fabricated and tested for marginal distortion at four firing cycles using image analyzer and special software (Leco Version La 32) in which instead of measuring at points an area was measured that gives a computed mean measured thickness of marginal distortion. Value obtained were evaluated for significance using two tailed, unpaired, student t test and Tukeys-Kramer multiple comparison test. Finesse all ceramic crown system showed continued clinically acceptable marginal distortion through all firing cycles (12.84 μm). Greatest distortion of metal ceramic system occurred during degassing cycle(16.90 μm). In respect of marginal fit all ceramic (finesse) crowns is better choice when esthetics is more concern.     

Long‐Term Function of Single‐Implant Restorations: A 17‐ to 19‐Year Follow‐Up Study on Implant Infraposition Related to the Shape of the Face and Patients' Satisfaction

Background: Various levels of infraposition of single‐implant restorations have been observed in long‐term follow‐up studies, but little knowledge is available on the biological mechanism behind this pattern. Purpose: The primary aim of this study is to report the frequency and severeness of implant infraposition in the anterior single‐implant application after 17 to 19 years in function and, secondly, to try to relate these observations to anatomical appearance of the shape of the face of the patient. Materials and Methods: The present study comprised of 57 patients who were provided with 65 CeraOne? single‐tooth restorations (Nobel Biocare AB, Gothenburg, Sweden) between 1989 and 1991. Altogether 46 of these patients were treated with single implants in the anterior region. Besides clinical and radiographic data, clinical photographs, study casts, and patient's assessment of the long‐term aesthetic result (visual analog scale) was collected at the termination of the present study. The degree of implant crown infraposition was related to assessed facial shape and to patient and clinical assessment of the aesthetic result by means of Pearson's correlation test. To increase the numbers of patients, another group of 25 patients presented in another similar study were pooled with the present material for prevalence calculations. Results: Altogether 47 patients showed up for the final examination after an average of 18 years (82%). Two implants failed (18 years cumulative survival rates [CSR]– 96.8%) and eight original single‐crown restorations were replaced (CSR 83.8%). Three of the replaced crowns were replaced because of infraposition of the crowns. About 40% of the patients showed signs of infraposition, similar in younger and older age groups, but more frequently observed in female patients at termination of the study (p < 0.05). There was a weak trend indicating an association between “long‐face” appearance and infraposition of the crown restoration (p > 0.05), and patients were more satisfied with the aesthetic clinical result than the participating clinicians (p < 0.05). Conclusion: Single‐implant restorations in the anterior upper jaw may present small degrees of infraposition in long‐term perspectives. Female patients seem to be at a higher risk of infraposition (p < 0.05), but no clear relationship between age at implant placement or facial shape and degree of infraposition was possible to establish (p > 0.05). Patients were more satisfied with the aesthetic result, as compared with the clinicians (p < 0.05), and patients seemed to pay less attention to the degree of infraposition in their aesthetic assessments, as compared with most of the clinicians.     

Crestal Bone Changes at Teeth and Implants in Periodontally Healthy and Periodontally Compromised Patients. A 10‐Year Comparative Case‐Series Study

Background: Limited data exist on the longitudinal crestal bone changes around teeth compared with implants in partially edentulous patients. This study sought to compare the 10‐year radiographic crestal bone changes (bone level [BL]) around teeth and implants in periodontally compromised (PCPs) and periodontally healthy (PHPs) patients. Methods: A total of 120 patients were evaluated for the radiographic crestal BL around dental implants and adjacent teeth at time of implant crown insertion and at the 10‐year follow‐up. Sixty patients had a previous history of periodontitis (PCPs), and the remaining 60 were PHPs. In each category (PCP and PHP), two different implant systems were used. The mean BL change at the implant and at the adjacent tooth at the interproximal area was calculated by subtracting the radiographic crestal BL at the time of crown cementation from the radiographic crestal BL at the 10‐year follow‐up. Results: At 10 years after therapy, the survival rate ranged from 80% to 95% for subgroups for implants, whereas it was 100% for the adjacent teeth. In all eight different patient categories evaluated, teeth demonstrated a significantly more stable radiographic BL compared with adjacent dental implants (teeth BL, 0.44 ± 0.23 mm; implant BL, 2.28 ± 0.72 mm; P <0.05). Radiographic BL changes around teeth seemed not to be influenced by the presence or absence of advanced bone loss (≥3 mm) at the adjacent implants. Conclusions: Natural teeth yielded better long‐term results with respect to survival rate and marginal BL changes compared with dental implants. Moreover, these findings also extend to teeth with an initial reduced periodontal attachment level, provided adequate periodontal treatment and maintenance are performed. As a consequence, the decision of tooth extraction attributable to periodontal reasons in favor of a dental implant should be carefully considered in partially edentulous patients.     

Long‐Term Effect of Surface Roughness and Patients' Factors on Crestal Bone Loss at Dental Implants. A Systematic Review and Meta‐Analysis

Publications from 2011 to 2015 were selected to evaluate effect of implant surface roughness on long‐term bone loss as surrogate for peri‐implantitis risk. 87 out of 2,566 papers reported the mean bone loss after at least 5 years of function. Estimation of the proportion of implants with bone loss above 1, 2, and 3 mm as well as analysis the effect of implant surface roughness, smoking, and history of periodontitis was performed. By means of the provided statistical information of bone loss (mean and standard deviation) the prevalence of implants with bone loss ranging from 1 to 3 mm was estimated. The bone loss was used as a surrogate parameter for “peri‐implantitis” given the fact that “peri‐implantitis” prevalence was not reported in most studies or when reported, the diagnostic criteria were unclear or of dubious quality. The outcome of this review suggests that peri‐implant bone loss around minimally rough implant systems was statistically significant less in comparison to the moderately rough and rough implant systems. No statistically significant difference was observed between moderately rough and rough implant systems. The studies that compared implants with comparable design and different surface roughness, showed less average peri‐implant bone loss around the less rough surfaces in the meta‐analysis. However, due to the heterogeneity of the papers and the multifactorial cause for bone loss, the impact of surface roughness alone seems rather limited and of minimal clinical importance. Irrespective of surface topography or implant brand, the average weighted implant survival rate was 97.3% after 5 years or more of loading. If considering 3 mm bone loss after at least 5 years to represent the presence of “peri‐implantitis,” less than 5% of the implants were affected. The meta‐analysis indicated that periodontal history and smoking habits yielded more bone loss.     

Effect of Fluoxetine on Periodontal Status in Patients With Depression: A Cross‐Sectional Observational Study

Background: Fluoxetine, a selective serotonin reuptake inhibitor, has been reported to reduce periodontal disease severity in a rat ligature‐induced periodontitis model. The objective of the present study is to investigate the influence of fluoxetine intake on periodontal parameters in patients with periodontitis with clinical depression. Methods: A sample of 236 patients with chronic periodontitis and clinical depression were assessed for clinical parameters of periodontal disease. Of these, 115 patients were taking fluoxetine (20 mg/day) for ≥2 months, and 121 patients were not. Participants taking fluoxetine were further analyzed for correlation between duration of drug intake and periodontal parameters. Results: All periodontal parameters, except plaque index, were significantly lower in participants taking fluoxetine (P <0.01). Partial correlation analysis, adjusted for confounders, revealed a significant and negative correlation between duration of fluoxetine intake and attachment loss (AL) (R² = ?0.321, P <0.05). Logistic regression analysis revealed that fluoxetine intake was associated with a lower risk of having AL ≥3 (odds ratio [OR] = 0.55, 95% confidence interval [CI] = 0.31 to 0.96) and lower odds of increased bleeding on probing (BOP) percentage values (OR = 0.62, 95% CI = 0.34 to 0.97). Conclusion: In this observational study, use of fluoxetine was associated with lower BOP percentages and reduced AL.     

Marginal Bone‐Level Alterations at Implants Installed in Block versus Particulate Onlay Bone Grafts Mixed with Platelet‐Rich Plasma in Atrophic Maxilla. A Prospective 5‐Year Follow‐Up Study of 15 Patients

Background: Extensive atrophy of the alveolar process may require a bone‐grafting procedure prior to implant treatment. Autogenous bone grafts from the iliac crest, used as onlay block and particulate bone, have been used together with sinus‐lift procedure in order to rehabilitate patients with extremely resorbed maxillae. However, there are to our knowledge no 5‐year follow‐up studies evaluating the extent of bone‐level change in patients treated with respectively block and particulate autogenous bone grafts. Purpose: The purpose of this prospective clinical study was to conduct a 5‐year follow‐up analysis with focus on bone‐level alteration in block versus particulate onlay bone grafts. Material and Methods: Fifteen out of originally 19 patients who were treated with iliac bone grafts and oral implants in the maxilla have been followed through the first 5 postoperative years. In a first study conducted on 19 patients, the role of platelet‐rich plasma in conjunction with autogenous bone was evaluated. In this 5‐year follow‐up study, the marginal bone alterations have been documented at base line, 1 year and 5 years of loading to the nearest 0,1 mm at mesial and distal surfaces of the implants. Two implants were installed on each side of the midline in either block or particulate bone grafts giving test and control sides in each patient. Additionally, two implants on each side were installed in residual bone/grafted sinus floor. Result: Marginal bone alteration in the anterior maxilla appeared larger at the side augmented by block bone at baseline, and after 1 and 5 years of loading, but the change was not statistically significant. Moreover, there was a significantly higher degree of marginal alteration during the first year of loading, compared with the examinations after 5 years. Conclusion: The present follow‐up study showed that there is no significant difference in the extension of resorption between block‐ and particulate autogenous bone grafts over a 5‐year period. Most of the resorption occurred during the first year in function.     

A 10‐Year Prospective Study of Single Tooth Implants Placed in the Anterior Maxilla

Purpose: The aim of the study was to evaluate the biological and technical outcomes of early and delayed placed single tooth implants after 10 years of follow‐up. Materials and Methods: Twenty consecutive patients who needed a single tooth replacement in the anterior maxilla were included in this study. Ten implants were placed with an early placement protocol, that is, 4 weeks after tooth extraction, whereas the other 10 implants were placed with a conventional delayed placement protocol, for example, 12 weeks after tooth extraction. At the baseline and at the annual re‐examinations, pain from implant regions, mobility, plaque, mucositis, and marginal bone levels were recorded. Biological and technical complications were registered. The patients evaluated the functional and aesthetic outcomes subjectively on a visual analogue scale after 3 and 10 years. Results: All implants were still in situ after 10 years. The cumulative implant survival rate was 100%. Two implant‐supported crowns were remade because of ceramic fractures. The 10‐year crown survival rate was 90%. No significant differences in implant survival rates were found between the early and delayed protocols, regarding plaque retention, mucositis, or marginal bone levels. After 10 years, the mean marginal bone loss at both sides of the implants was less than 1.0 mm in the two groups. During the 10‐year interval, 1 patient lost more than 1.5 mm of marginal bone, 3 patients lost between 1.0 mm and 1.4 mm of bone, and 16 patients lost less than 1.0 mm of bone as an average of the mesial and distal bone loss. Conclusions: This 10‐year prospective clinical trial demonstrated a 100% implant survival and a 90% crown survival. The average marginal bone level change was less than 1 mm, and there was no difference between early and delayed implant placement. Patient satisfaction with the implant‐supported single crowns reduced with time.