Titanium corrosion products from dental implants and their effect on cells and cytokine release: A review.

INTRODUCTION: Titanium is considered to be an inert material owing to the ability of the material to form a passive titanium oxide layer. However, once the titanium oxide layer is lost, it can lead to exposure of the underlying titanium substructure and can undergo corrosion. SUMMARY: The article explores the role of titanium ions and particles from dental implants on cells, cytokine release, and on the systemic redistribution of these particles as well as theories proposed to elucidate the effects of these particles on peri-implant inflammation based on evidence from in-vitro, human, and animal studies. Titanium particles and ions have a pro-inflammatory and cytotoxic effect on cells and promote the release of pro-inflammatory mediators like cytokines. Three theories to explain etiopathogenesis have been proposed, one based on microbial dysbiosis, the second based on titanium particles and ions and the third based on a synergistic effect between microbiome and titanium particles on the host. CONCLUSION: There is clear evidence from in-vitro and limited human and animal studies that titanium particles released from dental implants have a detrimental effect on cells directly and through the release of pro-inflammatory cytokines. Future clinical and translational studies are required to clarify the role of titanium particles and ions in peri-implant inflammation and the etiopathogenesis of peri-implantitis.

Association of adipokine levels with obesity in periodontal health and disease: A systematic review with meta-analysis and meta-regression.

This study aimed to investigate the levels of serum, gingival crevicular fluid (GCF), and salivary adipokines and their possible relationship with periodontitis and obesity. An electronic search was conducted in the following databases: PubMed/ Medline, Scopus, and EBSCOhost through February 2023. Two independent reviewers screened the titles, abstracts, and full text of all the studies. Studies comparing the levels of adipokines in GCF, serum, and/or saliva in subjects with obesity and periodontitis (group 1), subjects with normal weight and periodontitis (group 2), and subjects with obesity and gingival health (group 3) were included. Meta-analyses and meta-regression were performed on the data from included studies. Seventeen studies with study participants ranging from 30 to 120 were included with subjects in each group ranging from 10 to 40. There was a significant increase in levels of serum TNF-α, leptin, IL-6, and CRP between groups 1 and 2 (p < .05). In GCF, TNF-α and resistin levels were significantly higher (p < .05) in Group 1 vs. 2. Serum level of leptin was higher for group 1 vs. 3 (p < .05). Meta-regression analysis revealed that the obesity definition (body mass index (BMI) cut-off value >25 or >30) was significant for serum resistin (p < .05) and GCF resistin (p < .05) between group 1 and 2. The current analysis indicates that both periodontitis and obesity can modulate the pro-inflammatory cytokines at systemic and local levels. This bidirectional interaction of periodontitis and obesity via the inflammation pathway seems likely plausible. Further studies are required to elucidate this mechanism in more detail.

Association of F. alocis and D. pneumosintes with Periodontitis Disease Severity and Red Complex Bacteria.

Oral biofilms are considered the principal etiological agent in the development of periodontitis. Novel species that may contribute to periodontitis and dysbiosis have been identified recently. The study aims to evaluate the presence of F. alocis and D. pneumosintes in healthy and diseased patients and their association with clinical parameters and with red complex bacteria. The study included 60 subjects, with 30 patients each in the healthy and periodontitis groups. The clinical parameters were noted, and samples were subjected to DNA extraction followed by a polymerase chain reaction. Statistical analysis was performed using the Graph Pad Prism software. Results: F. alocis and D. pneumosintes were detected at a significantly higher percentage in the periodontitis group compared to the healthy group (p < 0.05). D. pneumosintes was significantly associated with T. forsythia in the periodontitis group (p < 0.05). Both of these organisms were present in sites with higher clinical attachment loss (p < 0.05). This study demonstrated that both F. alocis and D. pneumosintes were detected at a significantly higher percentage in periodontitis subjects and were detected more frequently in sites with a greater clinical attachment loss. It was also evident that both F. alocis and D. pneumosintes can be present independently of other putative periodontal pathogens.

Bibliometric Analysis of Dental Implantology Journals from 1991-2023.

Dental implants are an established treatment options for varying edentulous conditions and has grown in popularity since the 1990's. This increased clinical application has evidenced a parallel increase in dental implant related research. The objective of this paper was to perform a comprehensive bibliometric analysis of five dental implantology journals from 1991-2023. MATERIALS AND METHODS: We performed a search in the ISI Web of Science database between 1991 and 2023 in 5 journals with a focus on dental implantology: Clinical Oral Implant Research, Clinical Implant Dentistry and Related Research, Implant Dentistry, International Journal of Oral and Maxillofacial Implants, and International Journal of Oral Implantology. Results marked as correction, retraction notices, retracted articles, meeting abstract, withdrawn publications were removed from the analysis. The time period analyzed was divided into 4 decades: 1991-2000, 2001-2010, 2011-2020, 2021-2023. Additionally, the top 100 cited papers were also exported separately. Authors and countries with most publications were tabulated from the Web of Science database. VOS Viewer software was used to create network maps of keywords and title word occurrences for each of the time periods. Histcite software was used to analyze number of publications and citation counts. RESULTS: Network maps of keywords and title word occurrences suggested an early focus on osseointegration and titanium implants between 1991-2000. Publications between 2001-2010 saw a focus on in-vivo studies, implant surface and peri-implantitis. Publications post 2011 saw a focus on bone regeneration, complications and zygomatic implants. USA ranked highest in total number of publications in all time periods analyzed. CONCLUSIONS: Within the limitations of the study, we reported a comprehensive bibliometric analysis from 1990-2023. We identified trends in keywords and titles of dental implant publications in these journals which mirrored the trends seen in clinical practice.

Automated malarial retinopathy detection using transfer learning and multi-camera retinal images.

Cerebral malaria (CM) is a fatal syndrome found commonly in children less than 5 years old in Sub-saharan Africa and Asia. The retinal signs associated with CM are known as malarial retinopathy (MR), and they include highly specific retinal lesions such as whitening and hemorrhages. Detecting these lesions allows the detection of CM with high specificity. Up to 23% of CM, patients are over-diagnosed due to the presence of clinical symptoms also related to pneumonia, meningitis, or others. Therefore, patients go untreated for these pathologies, resulting in death or neurological disability. It is essential to have a low-cost and high-specificity diagnostic technique for CM detection, for which We developed a method based on transfer learning (TL). Models pre-trained with TL select the good quality retinal images, which are fed into another TL model to detect CM. This approach shows a 96% specificity with low-cost retinal cameras.

A Multistage Heterogeneous Stacking Ensemble Model for Augmented Infant Cry Classification.

Understanding the reason for an infant's cry is the most difficult thing for parents. There might be various reasons behind the baby's cry. It may be due to hunger, pain, sleep, or diaper-related problems. The key concept behind identifying the reason behind the infant's cry is mainly based on the varying patterns of the crying audio. The audio file comprises many features, which are highly important in classifying the results. It is important to convert the audio signals into the required spectrograms. In this article, we are trying to find efficient solutions to the problem of predicting the reason behind an infant's cry. In this article, we have used the Mel-frequency cepstral coefficients algorithm to generate the spectrograms and analyzed the varying feature vectors. We then came up with two approaches to obtain the experimental results. In the first approach, we used the Convolution Neural network (CNN) variants like VGG16 and YOLOv4 to classify the infant cry signals. In the second approach, a multistage heterogeneous stacking ensemble model was used for infant cry classification. Its major advantage was the inclusion of various advanced boosting algorithms at various levels. The proposed multistage heterogeneous stacking ensemble model had the edge over the other neural network models, especially in terms of overall performance and computing power. Finally, after many comparisons, the proposed model revealed the virtuoso performance and a mean classification accuracy of up to 93.7%.

Variation in the Occurrence of fimA Genotypes of Porphyromonas gingivalis in Periodontal Health and Disease.

Porphyromonas gingivalis is regarded as a "keystone pathogen" in periodontitis. The fimbria assists in the initial attachment, biofilm organization, and bacterial adhesion leading to the invasion and colonization of host epithelial cells. The present study aimed to investigate the occurrence of fimA genotypes in patients with chronic periodontitis and healthy individuals in the Indian population, and to study their association with the number of P. gingivalis cells obtained in subgingival plaque samples of these subjects. The study comprised 95 samples from the chronic periodontitis (CP) group and 35 samples from the healthy (H) group, which were detected positive for P. gingivalis in our previous study. Fimbrial genotyping was done by PCR and PCR-restriction fragment length polymorphism (RFLP). The fimA type II was more prevalent in the CP group (55.89%), followed by type IV (30.52%), whereas in the H group, type I was the most prevalent fimbria (51.42%). The quantity of P. gingivalis cells increased with the presence of fimA types II and III. Our results suggest a strong relationship between fimA types II and IV and periodontitis, and between type I and the healthy condition. The colonization of organisms was increased with the occurrence of type II in deep periodontal sites, which could play an important role in the progression of the disease.

Automated Detection of Malarial Retinopathy in Retinal Fundus Images obtained in Clinical Settings.

Cerebral malaria (CM) is a life-threatening clinical syndrome associated with 5-10% of malarial infection cases, most prevalent in Africa. About 23% of cerebral malaria cases are misdiagnosed as false positives, leading to inappropriate treatment and loss of lives. Malarial retinopathy (MR) is a retinal manifestation of CM that presents with a highly specific set of lesions. The detection of MR can reduce the false positive diagnosis of CM and alert physicians to investigate for other possible causes of the clinical symptoms and apply a more appropriate clinical intervention of underlying diseases. In order to facilitate easily accessible and affordable means of MR detection, we have developed an automated software system that detects the retinal lesions specific to MR, whitening and hemorrhages, using retinal color fundus images. The individual lesion detection algorithms were combined into an MR detection model using partial least square classifier. The classifier model was trained and tested on retinal image dataset obtained from 64 patients presenting with clinical signs of CM (44 with MR, 20 without MR). The MR detection model yielded specificity of 92% and sensitivity of 68%, with an AUC of 0.82. The proposed MR detection system demonstrates potential for broad screening of MR and can be integrated with a low-cost and portable retinal camera, to provide a bed-side tool for confirming CM diagnosis.

Detection of antibodies against Aggregatibacter actinomycetemcomitans in serum and saliva through ELISA in periodontally healthy individuals and individuals with chronic periodontitis.

BACKGROUND: Periodontitis is a persistent polymicrobial infection, which leads to chronic inflammation in the tooth supporting tissues. Aggregatibacter actinomycetemcomitans are normal commensals of oral cavity but are low in number in periodontally healthy subjects. They are one of the major pathogens aetiologically linked to periodontal disease. Plasma and salivary antibody measurement may be useful to support diagnosis, disease activity, classification and prognosis of periodontitis. The aim of the present study was to investigate the association between the serum and salivary antibody levels to A. actinomycetemcomitans and therefore, to find whether this association was varying in different grades of periodontitis. METHOD: Total of 50 periodontally healthy and 50 chronic periodontitis subjects (35-65 years) of both sexes were included for the study. 2 ml of un-stimulated saliva and 5 ml of venous blood was collected under sterile conditions. The detection of antibodies against A. actinomycetemcomitans in periodontally healthy individuals and individuals with chronic periodontitis was performed using indirect ELISA. RESULTS: Results showed serum IgG, IgA mean levels against A. actinomycetemcomitans were higher in chronic periodontitis subjects compared to mean levels in periodontally healthy subjects. Similarly, salivary IgG, IgA levels were also raised in chronic periodontitis patients as compared in healthy subjects. Also the mean levels of serum IgG and salivary IgA were increased as the severity of disease increased. CONCLUSION: Antibody titer using saliva and serum could be useful tool for screening of patients with chronic periodontitis. Further, monitoring the various phases of treatment outcome using saliva could be a useful, non-invasive, prognostic indicator.

Characterization and serotype distribution of Aggregatibacter actinomycetemcomitans: Relationship of serotypes to herpesvirus and periodontal status in Indian subjects.

BACKGROUND: The virulence of Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in any individual depends on the type of strain of this bacterium. To our knowledge, there have been no studies reported in Indian subjects about A. actinomycetemcomitans serotype occurrence, co-existence with herpes virus and the possible influence of such co-existence on periodontal pathology. METHODS: Subjects for this study were a subset of a larger study to identify the prevalence of A. actinomycetemcomitans in chronic periodontitis. A total of 63 subjects (12 periodontally healthy and 51 with chronic periodontitis) who were positive for A. actinomycetemcomitans were serotyped for strain-level identification. The presence of Human Cytomegalovirus (CMV) and Epstein-Barr virus (EBV) was tested in subgingival plaque samples by polymerase chain reaction. RESULTS: All five serotypes a to e were detected. Of the samples analyzed 38.09% harbored a single serotype, 36.5% had two serotypes, 6.3% demonstrated three and 4.7% demonstrated four serotypes. None of the samples showed presence of JP2 strain. Serotypes b, c, and e were most frequently identified in these individuals (46.03%, 36.5% and 38.09% respectively). Presence of serotypes b and c and absence of serotype d was associated with increased PD and CAL. Among 63 samples analyzed, 11 samples had CMV, four samples had EBV and nine samples had both these viruses. The PD and CAL were significantly higher (p = 0.04) when a combination of CMV and one of the serotypes was present indicating a pathological role of the coexistence. CONCLUSION: Multiple serotypes are associated with chronic periodontitis in Indians, however, JP2 strains are not detectable in this cohort. Presence of multiple serotypes and a combination of any serotype with herpesvirus is associated with greater severity of the disease.

A tale of two risks: smoking, diabetes and the subgingival microbiome.

Although smoking and diabetes have been established as the only two risk factors for periodontitis, their individual and synergistic impacts on the periodontal microbiome are not well studied. The present investigation analyzed 2.7 million 16S sequences from 175 non-smoking normoglycemic individuals (controls), smokers, diabetics and diabetic smokers with periodontitis as well as periodontally healthy controls, smokers and diabetics to assess subgingival bacterial biodiversity and co-occurrence patterns. The microbial signatures of periodontally healthy smokers, but not diabetics, were highly aligned with the disease-associated microbiomes of their respective cohorts. Diabetics were dominated by species belonging to Fusobacterium, Parvimonas, Peptostreptococcus, Gemella, Streptococcus, Leptotrichia, Filifactor, Veillonella, TM7 and Terrahemophilus. These microbiomes exhibited significant clustering based on HbA1c levels (pre-diabetic (<6.5%), diabetic (6.5-9.9%), diabetics >10%). Smokers with periodontitis evidenced a robust core microbiome (species identified in at least 80% of individuals) dominated by anaerobes, with inter-individual differences attributable largely to the 'rare biosphere'. Diabetics and diabetic smokers, on the other hand, were microbially heterogeneous and enriched for facultative species. In smokers, microbial co-occurrence networks were sparse and predominantly congeneric, while robust inter-generic networks were observed in diabetics and diabetic smokers. Smoking and hyperglycemia impact the subgingival microbiome in distinct ways, and when these perturbations intersect, their synergistic effect is greater than what would be expected from the sum of each effect separately. Thus, this study underscores the importance of early intervention strategies in maintaining health-compatible microbiomes in high-risk individuals, as well as the need to personalize these interventions based on the environmental perturbation.

Automated Detection of Malarial Retinopathy in Digital Fundus Images for Improved Diagnosis in Malawian Children with Clinically Defined Cerebral Malaria.

Cerebral malaria (CM), a complication of malaria infection, is the cause of the majority of malaria-associated deaths in African children. The standard clinical case definition for CM misclassifies ~25% of patients, but when malarial retinopathy (MR) is added to the clinical case definition, the specificity improves from 61% to 95%. Ocular fundoscopy requires expensive equipment and technical expertise not often available in malaria endemic settings, so we developed an automated software system to analyze retinal color images for MR lesions: retinal whitening, vessel discoloration, and white-centered hemorrhages. The individual lesion detection algorithms were combined using a partial least square classifier to determine the presence or absence of MR. We used a retrospective retinal image dataset of 86 pediatric patients with clinically defined CM (70 with MR and 16 without) to evaluate the algorithm performance. Our goal was to reduce the false positive rate of CM diagnosis, and so the algorithms were tuned at high specificity. This yielded sensitivity/specificity of 95%/100% for the detection of MR overall, and 65%/94% for retinal whitening, 62%/100% for vessel discoloration, and 73%/96% for hemorrhages. This automated system for detecting MR using retinal color images has the potential to improve the accuracy of CM diagnosis.

Comparative evaluation of the efficacy of a herbal mouthwash and chlorhexidine mouthwash on select periodontal pathogens: An in vitro and ex vivo study.

BACKGROUND: Several herbal mouthwash and herbal extracts have been tested in vitro and in vivo in search of a suitable adjunct to mechanical therapy for long-term use. In this study, we aimed to look at the antimicrobial effect of the herbal mouthwash and chlorhexidine (CHX) mouthwash on select organisms in in vitro test and an ex vivo model. MATERIALS AND METHODS: The antimicrobial effects were determined against standard strains of bacteria that are involved in different stages of periodontal diseases. The in vitro tests included determination of minimum inhibitory concentration (MIC) using broth dilution and agar diffusion. In the ex vivo part of the study supragingival dental plaque were obtained from 20 periodontally healthy adult volunteers. Descriptive analysis was done for the entire quantitative and qualitative variable recorded. RESULTS: The MIC by broth dilution method found no statistically significant difference between the mouthwashes. The agar dilution method showed CHX was more effective as compared to the herbal mouthwash against standard strains of Streptococcus mutans, Streptococcus sanguinis, and Aggregatibacter actinomycetemcomitans. However, no difference was observed between the mouthwashes for Porphyromonas, Pseudomonas aeruginosa, and Fusobacterium nucleatum. The ex vivo results conclude that none of the selected mouthwashes were statistically significantly different from each other. CONCLUSION: In the present study, CHX showed higher levels of antimicrobial action than the herbal mouthwash against bacterial species. The results reinforce the earlier findings that the in vitro testing is sensitive to methods and due diligence is needed when extrapolating the data for further use. However, long-term use and in vivo effectiveness against the periopathogens need to be tested in well-planned clinical trials.

Indirect immunofluorescence technique to study expression of toll-like receptor 4 in chronic periodontitis.

AIM: The aim of this study was to analyze the expression level and localization of Toll-like receptor (TLR) 4 in gingival samples of healthy and chronic periodontitis subjects by indirect immunofluorescence technique (IFT). MATERIALS AND METHODS: In this study, gingival tissue samples were obtained from 25 healthy and 25 periodontitis individuals. The tissues were processed and the initial characterization was done by hematoxylin and eosin staining. The expression and localization of the TLR4 receptor were determined in the epithelial and connective layer cells of the gingival tissue using the indirect IFT. Immunofluorescence images were acquired and quantitative expression of TLRs was analyzed by calculating the percentage of cells showing positive results. RESULTS: We found that the healthy control group exhibited significantly lower values of TLR4 expression in comparison with the periodontitis patients. We also found that in patients with periodontitis the concentration of TLR4 was higher in the epithelium as compared to their expression in connective tissue cells. CONCLUSIONS: These data suggested a definite involvement of TLR4 in initiating and progression of an inflammatory response in periodontitis.

Occurrence of Aggregatibacter actinomycetemcomitans in Indian chronic periodontitis patients and periodontally healthy adults.

BACKGROUND: Aggregatibacter actinomycetemcomitans (Aa), an important primary periodontal pathogen, is known for its strong virulence characteristics that cause periodontal disease. We investigated Aa occurrence in Indian individuals using culture and 16 s rDNA polymerase chain reaction (PCR). MATERIALS AND METHODS: A cross-sectional study with 100 participants each in the healthy and chronic periodontitis (CP) groups was conducted. The subgingival plaque was collected and immediately plated on selective media for Aa. The remaining plaque samples were used for DNA extraction. PCR was performed using specific primers for Aa. STATISTICAL ANALYSIS USED: The detection of bacteria and the clinical parameters between the groups were compared using the Mann-Whitney U-test. For assessing the agreement between the results of anaerobic culture and PCR, Kappa analyses were performed. RESULTS: Aa levels using culture and PCR was 51% and 69% in the CP group and 12% and 30% in the healthy group, respectively. The two groups showed significant differences (P < 0.00001). The detection accuracy of culture and PCR was assessed, and the coefficient of accuracy (k) was highly significant in the healthy (0.3103; P < 0.0001) and CP groups (0.1536; P < 0.0497). CONCLUSIONS: Aa was predominantly found in the CP group compared with the healthy group, which is consistent with previous findings. Our results showed that both techniques can be used for detecting Aa. An ideal technique for detecting subgingival microorganisms should be carefully selected depending on the scope of the intended future work.

Comparison of the effectiveness of three retinal camera technologies for malarial retinopathy detection in Malawi.

The purpose of this study was to test the suitability of three available camera technologies (desktop, portable, and i-phone based) for imaging comatose children who presented with clinical symptoms of malaria. Ultimately, the results of the project would form the basis for a design of a future camera to screen for malaria retinopathy (MR) in a resource challenged environment. The desktop, portable, and i-phone based cameras were represented by the Topcon, Pictor Plus, and Peek cameras, respectively. These cameras were tested on N=23 children presenting with symptoms of cerebral malaria (CM) at a malaria clinic, Queen Elizabeth Teaching Hospital in Malawi, Africa. Each patient was dilated for binocular indirect ophthalmoscopy (BIO) exam by an ophthalmologist followed by imaging with all three cameras. Each of the cases was graded according to an internationally established protocol and compared to the BIO as the clinical ground truth. The reader used three principal retinal lesions as markers for MR: hemorrhages, retinal whitening, and vessel discoloration. The study found that the mid-priced Pictor Plus hand-held camera performed considerably better than the lower price mobile phone-based camera, and slightly the higher priced table top camera. When comparing the readings of digital images against the clinical reference standard (BIO), the Pictor Plus camera had sensitivity and specificity for MR of 100% and 87%, respectively. This compares to a sensitivity and specificity of 87% and 75% for the i-phone based camera and 100% and 75% for the desktop camera. The drawback of all the cameras were their limited field of view which did not allow complete view of the periphery where vessel discoloration occurs most frequently. The consequence was that vessel discoloration was not addressed in this study. None of the cameras offered real-time image quality assessment to ensure high quality images to afford the best possible opportunity for reading by a remotely located specialist.

Prevalence of Herpesvirus and Correlation with Clinical Parameters in Indian Subjects with Chronic Periodontitis.

OBJECTIVE: The identification of new uncultured species and viruses supports the possibility of combination of the herpes-virus-bacterial periodontal infection for periodontitis. The paucity of data and studies with larger sample size in Indian subjects provides an unclear picture of the presence of the herpesvirus in this population. MATERIALS AND METHODS: This was a cross-sectional study consisting of 100 each in the healthy group and chronic periodontitis (CP) group. The subgingival plaque was collected and polymerase chain reaction was performed post deoxyribonucleic acid (DNA) extraction by using specific primers for human cytomegalovirus (HCMV) and Epstein-Barr virus (EBV). The data were analyzed using Fisher's exact test, Mann-Whitney U test and Spearman's coefficient correlation. RESULTS: Human cytomegalovirus and EBV viruses were significantly higher in the CP group as compare to the healthy group. A higher percentage of those with CMV positive had EBV also positive (28.3%) compared to only 9.1% of CMV negative being EBV positive in the CP group. When both the healthy and CP group in total was compared, there was a significant correlation with all clinical parameters. CONCLUSION: Both the viruses dominated in disease as compared to health were similar to the earlier findings. The CP group had higher pocket depth and clinical attachment loss in the virus positive subjects. These findings could suggest that virus serves as a prelude to the disease and the combination of the two viruses could play a role in the pathogenesis.

Smoking decreases structural and functional resilience in the subgingival ecosystem.

AIMS: Dysbiotic microbial communities underlie the aetiology of several oral diseases, especially in smokers. The ability of an ecosystem to rebound from the dysbiotic state and re-establish a health-compatible community, a characteristic known as resilience, plays an important role in susceptibility to future disease. The present investigation was undertaken to examine the effects of smoking on colonization dynamics and resilience in marginal and subgingival biofilms. MATERIALS AND METHODS: Marginal and subgingival plaque and gingival crevicular fluid samples were collected from 25 current and 25 never smokers with pre-existing gingivitis at baseline, following resolution, after 1, 2 4, 7, 14 and 21 days of undisturbed plaque formation and following resolution. 16S cloning and sequencing was used for bacterial identification and multiplexed bead-based flow cytometry was used to quantify the levels of 27 immune mediators. RESULTS: Smokers demonstrated an early pathogenic colonization that led to sustained pathogen enrichment with periodontal and respiratory pathogens, eliciting a florid immune response. Smokers also demonstrated greater abundance of pathogenic species, poor compositional correlation between marginal and subgingival ecosystems, and significantly greater pro-inflammatory responses following resolution of the second episode of disease. CONCLUSIONS: The ability of the subgingival microbiome to "reset" itself following episodes of disease is decreased in smokers, thereby lowering the resilience of the ecosystem and decreasing its resistance to future disease.

Automated method for identification and artery-venous classification of vessel trees in retinal vessel networks.

The separation of the retinal vessel network into distinct arterial and venous vessel trees is of high interest. We propose an automated method for identification and separation of retinal vessel trees in a retinal color image by converting a vessel segmentation image into a vessel segment map and identifying the individual vessel trees by graph search. Orientation, width, and intensity of each vessel segment are utilized to find the optimal graph of vessel segments. The separated vessel trees are labeled as primary vessel or branches. We utilize the separated vessel trees for arterial-venous (AV) classification, based on the color properties of the vessels in each tree graph. We applied our approach to a dataset of 50 fundus images from 50 subjects. The proposed method resulted in an accuracy of 91.44% correctly classified vessel pixels as either artery or vein. The accuracy of correctly classified major vessel segments was 96.42%.