College of Dentistry - M.Dent. Projects
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- ItemOpen AccessUnraveling the Peri-Implant Epithelial Barrier(2025-06-18) Grauer, Joseph; Helms, Jill (Stanford University, Surgery); Stavropoulou, Chrysi (Periodontics); Kelekis-Cholakis, Anastasia (Dentistry); Bhullar, Raj (Oral Biology); Helms, Jill; Stavropoulou, ChrysiThe long-term success of dental implants relies on the formation of a protective soft tissue barrier that limits pathogen infiltration into peri-implant tissues. However, our understanding of how this barrier develops under different implant placement protocols (i.e., immediate vs. delayed placement) and in response to varying implant surface characteristics remains limited. This study systematically evaluates the formation and maturation of peri-implant soft tissues in two contexts: (1) immediate versus delayed implant placement and (2) anodized versus machined implant surfaces. Part I: Miniaturized titanium implants were placed in either fresh extraction sockets or healed maxillary first molar sites in mice. Peri-implant soft tissues were assessed at multiple time points to investigate molecular attachment mechanisms and the barrier function of the soft tissue. A healthy junctional epithelium served as a positive control. Notably, no significant differences were observed in the rate of soft tissue integration between immediate and delayed implants. However, mucosal integration took at least twice as long as osseointegration in this model. Part II: Scanning electron microscopy and surface chemistry characterization were performed on miniaturized anodized and machined implants. Following placement in fresh extraction sockets, peri-implant tissues were examined at four time points. The findings corroborated those from Part I and led to several key conclusions: 1. Maturation of the peri-implant epithelium (PIE) is a prolonged process, aligning with clinical observations. 2. Soft tissue integration occurs more slowly than bone integration. 3. Anodized implant surfaces offer a transient advantage in promoting soft tissue maturation. Together, these findings highlight the extended timeline required for PIE maturation, underscoring the potential clinical benefits of strategies aimed at accelerating this process.
- ItemOpen AccessAn Evaluation of Handheld Ultrasonography in Comparison to MRI for the Diagnosis of Temporomandibular Joint Disorders(2025-10-11) Brown, Meagan; Todescan, Reynaldo; Bhullar, Raj; Shah, Adnan; Elgazzar, Reda; Dale, Catherine; Shah, Adnan; Elgazzar, Reda; Dale , CatherineMRI is the gold standard of imaging modalities for the diagnoses of internal derangement (ID) of the Temporomandibular Joint (TMJ). MRI scans are non-invasive, use non-ionizing radiation, and provide valuable information on the position and morphology of joints, tissues and bony structures. MRI has disadvantages and patients with severe TMJ pain may find it difficult to complete a full TMJ scan series. The heavy demand for MRI utilization and resulting wait times prolong the interval between initial consultation and diagnosis. MRI is also expensive, inconvenient, and contraindicated in patients with certain metallic implants (Orhan & Aksoy, 2019). For these reasons, the author believes that finding an alternative diagnostic device for ID that is convenient and reliable is of critical importance. There is a limited body of encouraging evidence demonstrating that mobile ultrasound sonography (mUS), can act as a diagnostic adjunct to MRI for assessment of Temporomandibular Joint Disorders (TMD’s), including ID and Degenerative Joint Disease (DJD). The use of mUS has no known contraindications, is readily accessible, comparatively inexpensive, and requires no special preparation (Orhan & Aksoy, 2019). The purpose of this paper is to summarize the findings of original research into the Accuracy of handheld ultrasound sonography (HHU), in comparison to MRI, for the diagnoses of patients with TMD. The scans focussed on Anterior Disk Displacement (ADD) without reduction (ADDwoR), ADD with reduction (ADDwR) and arthritic changes (OA). Using a 95% CI and 5% p-value, when diagnosing ADDwoR, HHU was found to have a Sensitivity of 96.77%, Specificity of 100%, PPV of 100%, and NPV of 90%. When diagnosing ADDwR, Sensitivity was 76.50%, Specificity 100%, PPV 100%, and NPV 85.20%. The perfect Specificity means HHU is good at identifying patients that have a normal disc-condyle relationship and do not have ADD, while the perfect PPV means a high likelihood the tested patient has ADD. Results indicate that HHU is a highly Specific test, with no false negatives, and an acceptable Sensitive test, with few false positives. HHU, in conjunction with questionnaires and clinical examination, shows promise as a first line imaging modality and screen for MRI referral.
- ItemOpen AccessAssessing the Biomechanical Impact of Dentition Types and Craniofacial Forms on Intact and Fractured Mandibles(2024-08-26) Zakeri, Mahdi; Elgazzar, Reda (Dept. Oral and Maxillofacial Surgery); Bhullar, Rajinder (Dept. of Oral Biology); Todescan, Reynold (Dept of Prosthodontics); Rickey, Daniel (Dept of Radiology); Shah, AdnanCurrency, Oral and maxillofacial surgeon globally dealing with some challenges in Management of Mandibular fracture. It is imperative for clinician to have in depth understanding of biomechanic of the intact and fractured mandible to be able to improve the quality care and prevent further complications associated with the effectiveness of the open reduction and internal fixation of mandibular fracture. It is also important for clinician to have a thorough understanding of bone biology and the healing process, and how it is directly affected by mechanical and biological factors.
- ItemOpen AccessThe role of the oral microbiota and intrinsic host factors in peri-implant diseases: peri-implant mucositis versus peri-implantitis(2024-08-11) Rozenblit, Amit; Kelekis-Cholakis, Anastasia (Dentistry); Chelikani, Prashen (Oral Biology); Bhullar, Raj (Dentistry); Stavropoulou, ChrysiAim: To characterize and compare the role of the oral microbiota and host biomarkers in patients with peri-implant mucositis and peri-implantitis. Methods: Patients diagnosed with either peri-implant mucositis (N=13) or peri-implantitis (N=20) were recruited from the Dr. Sam Borden Graduate Periodontics Clinic at the University of Manitoba. Subgingival plaque samples and crevicular fluid samples were collected from diseased implant sites and healthy natural teeth to study the local microbiome and host biomarker profiles, respectively. 16 rRNA and ITS rRNA amplicon sequencing were performed to detect bacterial and fungal species. Eight different cytokines were isolated and analyzed: IL-1β, IL-2, IL-4, IL-6, IL8, IL-10, IFN-γ, TNF-α. Results: Bacterial differential abundance analysis indicated statistically significant differences in the abundance of 17 different bacterial taxa and species between sites with peri-implant mucositis and peri-implantitis, most notably Tannerella forsythia was significantly more abundant at sites with peri-implantitis compared to sites with peri-implant mucositis. Fungal differential abundance analysis indicated that Malassezia species were significantly reduced in sites with peri-implant mucositis compared to sites with peri-implantitis. Cytokine analysis indicated no statistically significant differences in the crevicular concentrations of any cytokines analyzed between the peri-implant mucositis and peri-implantitis groups. Conclusion: Peri-implant mucositis and peri-implantitis have similar microbial communities and cytokine profiles; however, the presence of certain bacterial and fungal species may play a role in the transition between peri-implant diseases.
- ItemOpen AccessRole of oral microbiota and intrinsic host factors in peri-implantitis – a pilot study(2022-04-26) Enghiad, Setareh; Stavropoulou, Chrysi (Dr. Gerald Niznick College of Dentistry); Cholakis, Anastasia (Dr. Gerald Niznick College of Dentistry); Chelikani, Prashen (Dr. Gerald Niznick College of Dentistry); Bhullar, RajIntroduction: Although many studies have evaluated microbial composition of peri-implant pockets, the role of mycobiome on peri-implantitis is not well established. Objectives: The aim of this study is to characterize the role of oral microbiota in peri-implant health and disease by determining the composition of the oral bacteriome and mycobiome from subgingival dental plaque, cytokine profile in the crevicular fluid, and to determine if there are any relationships between the oral microbiota, cytokine profile and peri-implant health and disease. Methods: Gingival crevicular fluid and subgingival plaque samples were collected from 20 periodontally healthy patients with healthy implants [Group H] and 9 periodontally healthy patients with peri-implantitis [Group P]. Eight IL-1β, IFN-γ, IL-2, IL-4, IL-6, IL-8, IL-10, and TNF-α were analyzed in crevicular fluid samples isolated from both groups. 16S rRNA and ITS rRNA amplicon sequencing was performed to detect bacterial and fungal species. Results: No statistically significant difference was found in concentrations of IL-2, IL-8, IL-10, and TNF-α. However, statistically significant differences were observed for IL-4 and IL-6. Alpha diversity analysis showed a significant difference between the groups H - Implant vs. P - Tooth and P - Implant vs. P - Tooth. Significant differences in species abundances were also observed between Group H and Group P. Candida parapsilosis and Aspergillus restrictus were significantly enriched in the Group P. Conclusions: To the best of our knowledge, this is the first time Aspergillus restrictus is related to peri-implantitis. Moreover, we found that the relative abundance of Candida parapsilosis is significantly higher in peri-implantitis sites. Our findings further challenge the concept that peri- implantitis is a bacterial disease with specific bacterial pathogens and strengthens the idea that bacterial invasion happens secondary to bone loss because of not very well understood processes such as foreign body reaction.