Enhanced third-order nonlinear optical properties of ZnO@C-N composite microspheres.

We report the third-order nonlinear optical (NLO) properties of ZnO@C-N composite microspheres and pure ZnO which have been investigated with the Z-scan technique under continuous wave laser. ZnO@C-N composite microspheres have been hydrothermally synthesized at two different precursor concentrations to have structures at different impurity levels. Moreover, pure ZnO is prepared under the annealing process. The nonlinear optical absorption of samples was measured by using the open-aperture Z-scan technique and was evaluated relating to the two-photon absorption (TPA) mechanism. Moreover, both ZnO@C-N and ZnO microstructures exhibited a negative nonlinear refractive index (NLR) referring to the self-defocusing effect. The order of the (NLR) value, is about 10-10(cm2/W) and, the NLA coefficients of specimens are in the order of 10-5(cm/W). The NLA coefficient has a similar behavior as the NLR versus increasing incident intensity of the laser. The results show that the nonlinearity response of ZnO@C-N composites is higher than the pure ZnO and ZnO@C-N at higher precursor concentrations exhibits the maximum amount of NLA and NLR coefficients compared to other samples. This observation which is attributed to the change in optical and structural properties of material due to impurity presence, underscores the presence of impurity for engineering materials to improve the nonlinearity properties.

SURVIVAL RATE OF IMPLANT-SUPPORTED, SINGLE-TOOTH RESTORATIONS BASED ON ZIRCONIA OR METAL ABUTMENT IN PATIENTS WITH TOOTH AGENESIS: A 5-YEARS PROSPECTIVE CLINICAL STUDY.

OBJECTIVES: The primary aim was to investigate survival rate of zirconia versus metal abutments, and the secondary aim was clinical outcomes of all-ceramic versus metal-ceramic crowns on single-tooth implants. METHODS: Patients with tooth-agenesis participated to previously published prospective clinical study with 3-year follow-up were recalled after 5 years. Biological variables included survival and success rate of implants, marginal bone level, modified Plaque and Sulcus Bleeding Index and biological complications. Technical variables included restoration survival rate, marginal adaptation and technical complications. The aesthetic outcome of crowns and peri-implant mucosa in addition to patient-reported outcome were recorded. Descriptive analysis, linear mixed model for quantitative data, or generalized linear mixed model for ordinal categorical data were applied; significance was set to 0.05. RESULTS: Fifty-three patients (mean age: 32.4 years), with 89 implants participated to the 5-years examination. The implants supported 50 zirconia abutments with 50 all-ceramic (AC) crown and 39 metal abutments with 29 metal-ceramic (MC) and 10 AC crowns. The Implant and restoration survival rate was 100% and 96%, respectively. No clinically relevant biological difference between implants supporting metal or zirconia abutments was registered. The technical complications were veneering fracture of AC-crowns (n = 3), crown loosening of MC-crowns (n = 4) and one abutment screw loosening (MC-crown on metal abutment). MC-crowns had significantly better marginal adaptation than AC-crowns (p = .01). AC-crowns had significantly better color and morphology than MC-crowns (p = .01). CONCLUSIONS: Zirconia-based single-tooth restorations are reliable alternative materials to metal-based restorations with favorable biological and aesthetic outcome, and few technical complications.

Interpositional arthroplasty using cartilage allografts for treating temporomandibular joint arthrosis: a 3- and 5-year retrospective clinical follow-up study.

OBJECTIVE: To evaluate the effect of arthroplasty using interpositional cartilage allografts in patients with temporomandibular joint (TMJ) arthrosis. STUDY DESIGN: This retrospective study included patients treated consecutively between 2007 and 2013 using discectomy and interpositional grafting with lyophilized costal cartilage allograft (Tutoplast) sheets. TMJ pain based on the visual analogue scale (VAS), maximal interincisal opening (MIO), joint tenderness to palpation, crepitus from the affected joint, and postoperative complications were assessed. RESULTS: Arthroplasty was performed on 37 joints among 34 patients (28 women; mean age: 54 years); 24 joints underwent simultaneous condyle shaving. At final follow-up (3 [n = 37] or 5 [n = 21] years), we observed reduced mean VAS (from 7.6 to 0.9; P < .001) increased mean MIO (from 32.5 to 41.1 mm; P < .001), number of joints with capsule tenderness (from 30 to 3; P < .001), and percentage of joints with crepitus (from 97% to 75%; P = .008). One joint required reoperation because of interposed cartilage fragmentation. No permanent facial nerve injury or malocclusion occurred after treatment. CONCLUSIONS: Interpositional arthroplasty is a relatively simple, moderately invasive, and effective surgical treatment for TMJ arthrosis with few complications. However, long-term outcomes of this treatment, specifically beyond 3-5 years postoperatively, remain unknown.

Leveraging Large Language Models for Clinical Abbreviation Disambiguation.

Clinical abbreviation disambiguation is a crucial task in the biomedical domain, as the accurate identification of the intended meanings or expansions of abbreviations in clinical texts is vital for medical information retrieval and analysis. Existing approaches have shown promising results, but challenges such as limited instances and ambiguous interpretations persist. In this paper, we propose an approach to address these challenges and enhance the performance of clinical abbreviation disambiguation. Our objective is to leverage the power of Large Language Models (LLMs) and employ a Generative Model (GM) to augment the dataset with contextually relevant instances, enabling more accurate disambiguation across diverse clinical contexts. We integrate the contextual understanding of LLMs, represented by BlueBERT and Transformers, with data augmentation using a Generative Model, called Biomedical Generative Pre-trained Transformer (BIOGPT), that is pretrained on an extensive corpus of biomedical literature to capture the intricacies of medical terminology and context. By providing the BIOGPT with relevant medical terms and sense information, we generate diverse instances of clinical text that accurately represent the intended meanings of abbreviations. We evaluate our approach on the widely recognized CASI dataset, carefully partitioned into training, validation, and test sets. The incorporation of data augmentation with the GM improves the model's performance, particularly for senses with limited instances, effectively addressing dataset imbalance and challenges posed by similar concepts. The results demonstrate the efficacy of our proposed method, showcasing the significance of LLMs and generative techniques in clinical abbreviation disambiguation. Our model achieves a good accuracy on the test set, outperforming previous methods.

Prediction of tsunami of resistance to some antibiotics is not far-fetched which used during COVID-19 pandemic.

One of the most tragic events in recent history was the COVID-19 outbreak, which has caused thousands of deaths. A variety of drugs were prescribed to improve the condition of patients, including antiparasitic, antiviral, antibiotics, and anti-inflammatory medicines. It must be understood, however, that COVID-19 is like a tip of an iceberg on the ocean, and the consequences of overuse of antibiotics are like the body of a mountain under water whose greatness has not yet been determined for humanity, and additional study is needed to understand them. History of the war between microbes and antimicrobial agents has shown that microbes are intelligent organisms that win over antimicrobial agents over time through many acquired or inherent mechanisms. The key terms containing "COVID-19," "Severe acute respiratory syndrome coronavirus-2," "SARS-CoV2," "Antibiotic Resistance," "Coronavirus," "Pandemic," "Antibiotics," and "Antimicrobial Resistance" were used for searching in PubMed, Scopus, and Google Scholar databases. The COVID-19 pandemic has resulted in an increased prescription of antibiotics. Infections caused by secondary or co-bacterial infections or beneficial bacteria in the body can be increased as a result of this amount of antibiotic prescription and exposure to antibiotics. Antibiotic resistance will likely pose a major problem in the future, especially for last resort antibiotics. In order to address the antibiotic resistance crisis, it is imperative that researchers, farmers, veterinarians, physicians, public and policymakers, pharmacists, other health and environmental professionals, and others collaborate during and beyond this pandemic.

Evaluation of hematological changes, oxidant/antioxidant status and immuno-logical responses in sheep and goats naturally infected with Linguatula serrata.

Linguatula serrata is a worldwide zoonotic food-borne parasite. The parasite is responsible for linguatulosis and poses a concern to human and animal health in endemic regions. This study investigated the hematological changes, oxidant/antioxidant status and immunological responses in goats and sheep naturally infected with L. serrata. Hematological changes, antioxidant enzymes and malondialdehyde (MDA) levels were measured. The level of inter-leukin-2 (IL-2), IL-4, IL-5, IL-10, and tumor necrosis factor alpha (TNF-α) mRNA expression was investigated in lymph nodes. According to the hemogram results, eosinophils were significantly increased in the infected goats and sheep, and Horizontal Gene Transfer (HGT), hematocrit (HCT), and mean corpuscular hemoglobin concentration (MCHC) were significantly decreased. The levels of MDA and the activity of glutathione peroxidase (GPx) were significantly higher in infected animals than in non-infected animals. However, the activity of superoxide dismutase (SOD) and catalase (CAT) was significantly lower in infected animals than in non-infected animals. A comparison of the cytokine mRNA expression in lymph nodes from infected and non-infected animals showed higher cytokine expression in the infected animals. Infection with L. serrata caused microcytic hypochromic and normocytic hypochromic anemia in goats and sheep. The inconsistent results of immunological changes were found in infected goats and sheep. In both animals, oxidative stress occurred and led to an increase in lipid peroxidation. L. serrata created a cytokine microenvironment biased towards the type 2 immune responses.

Narrow diameter implants to replace congenital missing maxillary lateral incisors: A 1-year prospective, controlled, clinical study.

OBJECTIVES: To report the clinical, radiographic, esthetic, and patient-reported outcomes after placement of a newly developed narrow-diameter implant (NDI) in patients with congenitally missing lateral incisors (MLIs). MATERIALS AND METHODS: Patients with MLIs with a mesio-distal distance between the canine and the central incisor of 5.9-6.3 mm received a dental implant with a diameter of 2.9 mm (Test), while a diameter of 3.3 mm (Control) was used when the distance was 6.4-7.1 mm. After healing, a cement-retained bi-layered zirconia crown was fabricated. At the 1-year follow-up (T2), implant survival rate, marginal crestal bone level (CBL) changes, biological and technical complications were registered. The esthetic outcome was assessed by using the Copenhagen index score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. RESULTS: One hundred patients rehabilitated with 100 dental implants Ø0.9 mm (n = 50) or Ø3.3 mm (n = 50) were included. One Ø3.3 mm implant was lost, and seven patients dropped out of the study, yielding an implant survival rate of 99% (p = 1.000). At T2 a. CBL of -0.19 ± 0.25 mm (Test) and -0.25 ± 0.31 mm (Control) was detected, with no statistically significant difference between the groups (p = .342). Good to excellent esthetic scores (i.e., 1-2) were recorded in most of cases. Technical complications (i.e., loss of retention, abutment fracture, and chipping of veneering ceramic) occurred once in three patients with no statistically significant difference between the groups (p > .05). OHIP scores did not differ significantly at follow-ups between groups (p = .110). CONCLUSION: The use of Ø2.9 mm diameter implants represents as reliable a treatment option as Ø3.3 mm implants, in terms of CBL changes, biological and technical complications. Favorable esthetics and patient-reported outcomes were recorded for both groups.

A 5-year randomized controlled trial comparing zirconia-based versus metal-based implant-supported single-tooth restorations in the premolar region.

OBJECTIVE: To compare 5-year biological, technical, aesthetic, and patient-reported outcomes of single-tooth implant-supported all-ceramic versus metal-ceramic restorations. MATERIALS AND METHODS: Thirty patients with 63 premolar agenesis participated in the 5-year follow-up. The prosthetic treatment on single-tooth implants was randomly assigned to all-ceramic crowns on zirconia abutments (AC = 31) or metal-ceramic crowns on metal abutments (MC = 32). All patients were recalled to clinical examinations at baseline, 1, 3, and 5 years after prosthetic treatments. Biological, technical, and aesthetic outcomes including complications were clinically and radiographically registered. The patient-reported outcomes were recorded using OHIP-49 questionnaire before treatment and at each follow-up examination. RESULTS: At the 5-year examination, the survival rate was 100% for implants and 100% for AC and 97% for MC crowns and abutments. The marginal bone loss after 5 years was minor and not significantly different (p = .056) between AC (mean: 0.3, SD: 1.1) and MC (mean: -0.1, SD: 0.4) restorations. The success rate of the implants based on marginal bone loss was 77.4% for AC- and 93.7% for MC restorations. The marginal adaptation was significantly better for MC than for AC restorations (p = .025). The aesthetic outcomes and patient-reported outcomes between AC and MC restorations were not significantly different. CONCLUSIONS: The biological, aesthetic and patient-reported outcomes for implant-supported AC and MC restorations were successful and with no significant difference after 5-years. The marginal adaptation of the MC crowns cemented on titanium abutments showed a significantly better fit than restorations based on zirconia crowns cemented on zirconia abutments.

Narrow-band random Raman lasing from Rhodamine 6G assisted by cascaded stimulated Raman scattering effect.

This study reports the first experimental observation of cascaded stimulated Raman scattering (SRS) generation in a colloidal disordered medium. Generation of the cascaded effect requires both a high Raman gain and pump power in the disordered medium. Here, to extend effective path lengths of photons into the Raman gain medium for producing additional SRS processes, ZnO microspheres with abundant nano-protrusions as suitable scattering centers are proposed. It is explained that nano-protrusions on the surface of the spheres can act as nano reflectors and significantly provide potent feedback in the disordered system. This provided feedback via nano-protrusions boosts cascaded SRS generation to allow the appearance of higher Raman signals of Rhodamine 6G dye solution at a low scatterer concentration of 5 mg/ml. The threshold for the formation of the first Raman signal is measured at about 60 mJ/pulse. Also, the evolution of Raman signals under several fixed pump pulses is examined to investigate the stability from pulse to pulse. Our findings provide promising perspectives for achieving the single-frequency laser sources and generate desirable wavelengths for specific applications.

Patient's perception of timing concepts in implant dentistry: A systematic review.

Protocols for implant dentistry, most frequently include periods until healing of the extraction sockets and osseointegration of the implant. Deductional thinking imply that patients would prefer if treatment time in implant dentistry were reduced. AIM: What is the patient perception of immediate or early implant placement or loading in comparison with traditional, delayed placement, and/or loading assessed by patient-reported outcome measures, as evidenced in randomized controlled clinical trials or prospective controlled studies? MATERIAL AND METHODS: A systematic review was performed following the PRISMA guidelines with a literature search up to June 30. All hits were imported into Rayyan online software and analyzed by two authors for eligibility. Cochrane RoB2.0 and Newcastle-Ottawa Scale were used to evaluate risk of bias in the individual studies. RESULTS: Of the initially 1439 articles, 76 underwent full-text analysis and finally 40 articles, representing 35 cohort studies, were included. The quality evaluation demonstrated some concerns among most of the studies. CONCLUSION: a) There is no strong evidence to support that the time for implant placement or loading of implant-supported single or short-span reconstructions or overdentures influence patients´ discomfort, satisfaction with function or esthetics or overall satisfaction with the implant treatment. b) There is some evidence that studies including edentulous patients rehabilitated with implant-supported full-arch FDPs demonstrate more satisfied patients with immediate than for the early or delayed loaded implant reconstructions after short time, but the difference is not clear one year after treatment.

Fully versus conventionally guided implant placement by dental students: A randomized controlled trial.

OBJECTIVE: To compare fully guided with conventionally guided implant surgery performed by dental students in terms of deviation of actual implant position from an ideal implant position. MATERIALS AND METHODS: Twenty-five patients in need of 26 straightforward implant-supported single crowns were randomly allocated to a fully guided (FG, n = 14) or a conventionally guided (CG, n = 12) implant surgery. In the preoperative CBCTs, 3 experienced investigators placed a virtual implant in the ideal position, twice, allowing deviational analysis in the facio-lingual (coronal) and mesio-distal (sagittal) planes for 7 parameters. Facio-lingual crestal deviation, facio-lingual apical deviation, facio-lingual angular deviation, mesio-distal crestal deviation, mesio-distal apical deviation, mesio-distal angular deviation, and vertical deviation between the ideal, virtually placed position and actual implant position for the FG and CG groups were compared statistically (p < .05). RESULTS: Statistically significant differences between ideal and actual implant position were only seen for the facio-lingual apical deviation (p = .047) and for the facio-lingual angular deviation (p = .019), where the CG group deviated more from the ideal position than the FG group. The 5 other examined variables did not show any significant differences, and none of the implants in the FG group and CG group were placed in conflict with the clinical guidelines. CONCLUSIONS: The present study reported no difference in 5 out of 7 deviational parameters concerning actual implant position in relation to ideal implant position between a FG and CG implant placement protocol performed by dental students. Facio-lingual angular deviation and apical deviation were lower, when a FG protocol was followed. All implants were positioned according to clinical guidelines.

Tissue changes at implant sites in the anterior maxilla with and without connective tissue grafting: A five-year prospective study.

OBJECTIVES: To evaluate the biological and aesthetic outcome of connective tissue grafting around single-tooth implant replacements in the anterior maxilla after five years. MATERIALS AND METHODS: Nineteen patients (mean age: 22) received 33 implants in combination with bone grafts. After healing, 10 implant sites received facial connective tissue grafts harvested from the palate (test group). The remaining 23 implant sites without soft tissue grafts were used as a control group. The biological outcomes included survival rate, complications, marginal bone level, keratinized mucosa height and soft tissue level. The aesthetic outcomes included soft tissue thickness, spectrophotometric colour of mucosa, 3D facial dimensional changes and professional reported aesthetic outcomes. All data were recorded preoperatively and postoperatively after six months and one, three and five years. RESULTS: After five years, the survival and success rate of implants was 100% and 93.9% (one aesthetic and one biological complication). The soft tissue level changed significantly more towards the incisal direction in the test than in the control group from one to five years of observation (p = .024). The facial dimension increased significantly more in the test group than in the control group (3 mm marginally: p = .010). The subjective evaluation of mucosa colour was significantly better in the test versus control group (p = .035). Other biological and aesthetic parameters were not significantly different between the test and control group. CONCLUSION: Augmentation using a connective tissue graft may result in better mucosal colour match and more facial dimensional gain compared to implant sites without soft tissue grafting.

Influence of Restorative Materials on Color of Implant-Supported Single Crowns in Esthetic Zone: A Spectrophotometric Evaluation.

Restorations of 98 implant-supported single crowns in anterior maxillary area were divided into 5 groups: zirconia abutment, titanium abutment, and gold/gold hue abutment with zirconia coping, respectively, and titanium abutment with metal coping as well as gold/gold hue abutment with metal coping. A reflectance spectrophotometer was used to evaluate the color difference between the implant crowns and contralateral/neighboring teeth, as well as the color difference between the peri-implant soft tissue and the natural marginal mucosa. The mucosal discoloration score was used for subjective evaluation of the esthetic outcome of soft tissue around implant-supported single crowns in the anterior zone, and the crown color match score was used for subjective evaluation of the esthetic outcome of implant-supported restoration. ANOVA analysis was used to compare the differences among groups and Spearman correlation was used to test the relationships. A gold/gold hue abutment with zirconia coping was the best choice for an esthetic crown and the all-ceramic combination was the best for peri-implant soft tissue. Significant correlation was found between the spectrophotometric color difference of peri-implant soft tissue and mucosal discoloration score, while no significant correlation was found between the total spectrophotometric color difference of implant crown and crown color match score.

[Crown color match of implant-supported zirconia and porcelain-fused-to-metal restorations: a spectrophotometric comparison].

OBJECTIVE: This study aimed to compare the crown color match of implant-supported zirconia restorations and porcelain-fused-to-metal (PFM) restorations in the anterior maxillary region through spectrophotometric evaluation. METHODS: Eighteen patients with 29 implant-supported single crowns in the anterior maxillary area were recruited. Eleven of the implant crowns were zirconia restorations and 18 were PFM restorations. Color matching of the implant crown with contra-lateral/ neighboring tooth at the position of body 1/3 of the crown was assessed using a spectrophotometer (SpectroShade) in CIE L* a* b* coordinates. Subjective crown color match scores were evaluated. Independent sample t test of SPSS 17.0 was used to compare the difference between zirconia restoration and PFM restoration. Spearman correlation was used to analyze the relationship between the spectrophotometric color difference and the subjective crown color match score. Descriptive statistics was used to analyze the distribution of color coordinates of natural anterial teeth. RESULTS: The crown color of the implant-supported zirconia restorations and PFM restorations were both lighter than that of natural teeth (delta L, 4.5 +/- 3.2, 1.0 +/- 2.6). The lightness difference induced by zirconia restorations was significantly larger than that induced by PFM restorations (P=0.004). The spectrophotometric crown color difference (delta E) induced by zirconia restorations (7.0 +/- 2.8) was significantly larger than that induced by PFM restorations (4.0 +/- 1.9) (P=0.002), and both values were beyond the clinical thresholds (3.7). CONCLUSION: The spectrophotometric crown color difference induced by zirconia restorations was significantly larger than that induced by PFM restorations. However, they were indistinguishable in subjective evaluation.

Influence of implant position on clinical crown length and peri-implant soft tissue dimensions at implant-supported single crowns replacing maxillary central incisors.

The aims of this study were to evaluate the influence of implant position on clinical crown length and marginal soft tissue dimensions at implant-supported single crowns of maxillary central incisors and to validate the papilla index score (PIS). Twenty-five patients were included. Standardized and clinical photographs and periapical radiographs from baseline were used to assess three-dimensional positional parameters. The contralateral central incisors were used as controls. Paired sample t test and Pearson correlation analysis were used to analyze implant position, dimension of crown, and papilla fill. Cohen κ and Spearman correlation were used to validate the PIS. The implant-supported crown was statistically significantly longer than the contralateral tooth, and there was significant correlation between the orofacial position of the implant and the crown length difference. The distal papilla was significantly shorter than the mesial papilla at implant-supported crowns, but this difference was not significant at the contralateral tooth. A significant relationship between the PIS and papilla fill was found. An implant protruding the mucosa in a buccal position will result in an increased implant crown length compared to the contralateral tooth. Minor buccal angulations of the implant could be corrected with customized angulated abutments and did not necessarily result in an increased crown length. The distal implant papilla height was obviously shorter, although the mesial papilla height was similar to that of the healthy dentition. The PIS was found to be a valid index for papilla fill.

A 3-year prospective study of implant-supported, single-tooth restorations of all-ceramic and metal-ceramic materials in patients with tooth agenesis.

OBJECTIVES: The purpose of this clinical study was to describe outcome variables of all-ceramic and metal-ceramic implant-supported, single-tooth restorations. MATERIALS AND METHODS: A total of 59 patients (mean age: 27.9 years) with tooth agenesis and treated with 98 implant-supported single-tooth restorations were included in this study. Two patients did not attend baseline examination, but all patients were followed for 3 years. The implants supported 52 zirconia, 21 titanium and 25 gold alloy abutments, which retained 64 all-ceramic and 34 metal-ceramic crowns. At baseline and 3-year follow-up examinations, the biological outcome variables such as survival rate of implants, marginal bone level, modified Plaque Index (mPlI), modified Sulcus Bleeding Index (mBI) and biological complications were registered. The technical outcome variables included abutment and crown survival rate, marginal adaptation of crowns, cement excess and technical complications. The aesthetic outcome was assessed by using the Copenhagen Index Score, and the patient-reported outcomes were recorded using the OHIP-49 questionnaire. The statistical analyses were mainly performed by using mixed model of ANOVA for quantitative data and PROC NLMIXED for ordinal categorical data. RESULTS: The 3-year survival rate was 100% for implants and 97% for abutments and crowns. Significantly more marginal bone loss was registered at gold-alloy compared to zirconia abutments (P = 0.040). The mPlI and mBI were not significantly different at three abutment materials. The frequency of biological complications was higher at restorations with all-ceramic restorations than metal-ceramic crowns. Loss of retention, which was only observed at metal-ceramic crowns, was the most frequent technical complication, and the marginal adaptations of all-ceramic crowns were significantly less optimal than metal-ceramic crowns (P = 0.020). The professional-reported aesthetic outcome demonstrated significantly superior colour match of all-ceramic over metal-ceramic crowns (P = 0.015). However, no significant differences in the other aesthetic parameters at various restoration materials were registered. After 3 years, the patient-reported outcome variables at different restoration materials were not significantly different. CONCLUSION: The biological outcomes at the zirconia and metal abutments were comparable. All-ceramic crowns demonstrated better colour match, but higher frequency of marginal discrepancy compared to metal-ceramic crowns. Generally, the patients noticed no difference in aesthetic outcome of all-ceramic and metal-ceramic restorations.

Fracture mode during cyclic loading of implant-supported single-tooth restorations.

STATEMENT OF PROBLEM: Fracture of veneering ceramics in zirconia-based restorations has frequently been reported. Investigation of the fracture mode of implant-supported ceramic restorations by using clinically relevant laboratory protocols is needed. PURPOSE: This study compared the mode of fracture and number of cyclic loads until veneering fracture when ceramic and metal ceramic restorations with different veneering ceramics were supported by implants. MATERIAL AND METHODS: Thirty-two implant-supported single-tooth restorations were fabricated. The test group was composed of 16 ceramic restorations of zirconia abutment-retained crowns with zirconia copings veneered with glass-ceramics (n=8) and feldspathic ceramics (n=8). The control group was composed of 16 metal ceramic restorations of titanium abutment-retained crowns with gold alloy copings veneered with glass (n=8) and feldspathic ceramics (n=8). The palatal surfaces of the crowns were exposed to cyclic loading of 800 N with a frequency of 2 Hz, which continued to 4.2 million cycles or until fracture of the copings, abutments, or implants. The number of cycles and the fracture modes were recorded. The fracture modes were analyzed by descriptive analysis and the Mann-Whitney test (α=.05). The differences in loading cycles until veneering fracture were estimated with the Cox proportional hazards analysis. RESULTS: Veneering fracture was the most frequently observed fracture mode. The severity of fractures was significantly more in ceramic restorations than in metal ceramic restorations. Significantly more loading cycles until veneering fracture were estimated with metal ceramic restorations veneered with glass-ceramics than with other restorations. CONCLUSIONS: The metal ceramic restorations demonstrated fewer and less severe fractures and resisted more cyclic loads than the ceramic restorations, particularly when the metal ceramic crowns were veneered with glass-ceramics.

A feasible, aesthetic quality evaluation of implant-supported single crowns: an analysis of validity and reliability.

OBJECTIVES: To test the reliability and validity of six aesthetic parameters and to compare the professional- and patient-reported aesthetic outcomes. MATERIAL AND METHODS: Thirty-four patients with 66 implant-supported premolar crowns were included. Two prosthodontists and 11 dental students evaluated six aesthetic parameters, the Copenhagen Index Score (CIS): (i) crown morphology score, (ii) crown colour match score, (iii) symmetry/harmony score, (iv) mucosal discolouration score, (v) papilla index score, mesially and (vi) papilla index score, distally. The intra- and inter-observer agreement and the internal consistency were analysed by Cohen's κ and Cronbach's α, respectively. The validity of CIS parameters was tested against the corresponding Visual Analogue Scales (VAS) scores. The Spearman correlation coefficients were used. Six aesthetic Oral Health Impact Profile (OHIP) questions were correlated to the CIS and the overall VAS scores. RESULTS: The intra-observer agreement was >70% in 2/3 and >50% in all observations. The inter-observed agreement was >50% in 4/5 of all observations. The mucosal discolouration score had the overall highest observed agreement followed by the papilla index scores. The crown morphology and the symmetry/harmony scores had the overall lowest agreement. The Cronbach α value was over 0.8 for all observers. All CIS scores demonstrated significant (P<0.0001) correlation to the corresponding VAS scores. Low correlation coefficients (CIS/OHIP: r(s) <0.36; VAS/OHIP: r(s) >-0,24) were found between patient and professional evaluations. CONCLUSIONS: The feasibility, reliability and validity of the CIS make the parameters useful for quality control of implant-supported restorations. The professional- and patient-reported aesthetic outcomes had no significant correlation.

A 1-year randomised controlled trial comparing zirconia versus metal-ceramic implant supported single-tooth restorations.

PURPOSE: To compare the biological, technical and aesthetic outcomes of single implant-supported all-ceramic versus metal-ceramic crowns. MATERIALS AND METHODS: Thirty-six patients with premolar agenesis were randomly treated with 38 all-ceramic (AC) and 37 metal-ceramic (MC) implant-supported single-tooth restorations. A quasi-randomisation of consecutively included restorations in patients with one or more implants was used, i.e. a combination of parallel group (for 13 patients with one restoration) and split-mouth (for 23 patients with ≥2 restorations). All patients were recalled for baseline and 1-year followup examinations. Biological and technical outcomes, including complications, were clinically and radiographically registered. The Copenhagen Index Score and visual analogue scale (VAS) score were used to assess professional and patient-reported aesthetic outcomes, respectively, by blinded assessors. RESULTS: One-year after loading, no patient dropped out and no implant failed, though one MC restoration had to be remade. The marginal bone loss was not significantly different between AC and MC restorations (AC: mean 0.08 mm, SD 0.25; MC: mean 0.10 mm, SD 0.17). Seven out of 10 inflammatory reactions were registered at AC restorations. Two technical complications, one loss of retention and one chipping of veneering porcelain were recorded at two metal-ceramic crowns. The marginal adaptation of the all-ceramic crowns was significantly less optimal than the metal-ceramic crowns (P = 0.014). The professional-reported colour match of all-ceramic crowns was significantly better than metal-ceramic crowns (P = 0.031), but other aesthetic parameters as well as the VAS scores demonstrated no statistically significant difference between AC and MC restorations. CONCLUSIONS: Marginal bone loss and the aesthetic outcomes were not significantly different between AC and MC restorations in this short-term follow-up study, though inflammatory reactions in the peri-implant mucosa as well as less optimal marginal adaptation were more frequently registered for all-ceramic compared to the metal-ceramic crowns.