SMAD2 overexpression rescues the TGF-ß3 null mutant mice cleft palate by increased apoptosis.

During palatal development, medial edge epithelium (MEE) disappearance is one of the crucial steps in the process of fusion. The fate of these cells is still debated, and controversies remain. During secondary palate fusion, TGF-ß3 signaling mediated in the cell through the SMAD2 protein plays an important role and leads to the disappearance of the midline epithelial seam (MES) and the confluence of the palatal mesenchyme. In mice, TGF-ß3 knock-out is lethal and mice are born with a cleft in the secondary palate. This phenotype has been rescued by targeted overexpression of SMAD2 in the medial edge epithelium (MEE). The goal of this research was to understand the mechanism of palatal fusion in the rescue mice. METHODS: The heads of embryos with four different genotypes (wild-type, K14-SMAD2/TGF-ß3(-/-), K14-SMAD2/TGF-ß3(±), and TGF-ß3 null) were collected at embryonic day E14.5, genotyped, fixed and embedded in paraffin. Serial sections were studied for detection of apoptosis and epithelial mesenchymal transition using immunofluorescence. RESULTS: TGF-ß3 null mice developed a cleft in the secondary palate while both mice with K14-SMAD2 overexpression had fusion of the secondary palate. The MEE of both the rescue mice and K14-SMAD2 overexpression had a much higher ratio of apoptotic cells than wild-type mice. The increase in apoptosis was correlated with increased phospho-SMAD2 in the MEE. CONCLUSION: SMAD2 overexpression rescued the cleft in the secondary palate by increasing apoptosis in the medial edge epithelium.

Olmsted syndrome with oral involvement, including premature teeth loss.

INTRODUCTION: Olmsted syndrome is a rare palmoplantar keratodermal disease that has not previously been reported to have an association with periodontal disease. The aim of this study is to report and document a case of Olmsted syndrome with evidence of severe periodontal disease. CASE REPORT: A 38-year old Saudi male patient presented to the dental clinic diagnosed previously with Olmsted syndrome. Clinical and radiographic examinations were done and provided evidence of the typical clinical findings in Olmsted syndrome and evidence of severe periodontal disease. The patient had severe generalized hyperkeratotic lesions on the palms, soles, and perioral skin as well as hyperkeratosis of oral mucosa at multiple sites. CONCLUSION: This case report documents the first reported case of Olmsted syndrome to be associated with severe periodontal disease. The altered differentiation of oral mucosa linked to Olmsted syndrome may contribute to the periodontal disease. Patients diagnosed with this syndrome should receive a comprehensive oral examination to determine whether periodontal destruction is a significant component of their disease or not.

Multi-layered hypertrophied MEE formation by microtubule disruption via GEF-H1/RhoA/ROCK signaling pathway.

BACKGROUND: Formation of the secondary palate is complex and disturbance during palatal fusion may result in cleft palate. The processes of adhesion, intercalation, and disappearance of medial edge epithelia (MEE) are characterized by morphological changes requiring dynamic cytoskeletal rearrangement. Microtubules are one of the cytoskeletal elements involved in maintenance of cell morphology. Microtubule-disrupting drugs have been reported to cause craniofacial malformations including cleft palate. The mechanisms underlying the failure of palatal fusion remain poorly understood. We evaluated the effect of nocodazole (NDZ), a drug that disrupts microtubules, on palatal fusion in organ culture. RESULTS: NDZ caused failure of palatal fusion due to the induction of a multi-layered hypertrophied MEE in the mid-region of the secondary palatal shelves. Microtubule disruption increased RhoA activity and stress fiber formation. Pharmacological inhibition of the RhoA/ROCK pathway blocked multi-layered MEE formation. Partial prevention of hypertrophied MEE was observed with Y27632 and cytochalasin, but not with blebbistatin. NDZ induced re-localization of GEF-H1 into cytoplasm from cell-cell junctions. CONCLUSIONS: The present study provided evidence that the GEF-H1/RhoA/ROCK pathway plays a pivotal role in linking microtubule disassembly to the remodeling of the actin cytoskeleton, which resulted in a multi-layered hypertrophied MEE and failure of palatal fusion.

Professional identity formation: The key contributors and dental students' concerns.

OBJECTIVES: This study aimed to explore the components of professional identity formation (PIF) and understand dental students' concerns toward their professional identity development so that research-informed recommendations can be made to improve dental professional programs. METHODS: This is a qualitative study. A total of 18 students of the whole graduating class (class size: 46) were interviewed about their progress through a newly designed curriculum specific for the dental students at a large public research university in Canada. The audio files were recorded, transcribed, and corrected by a research assistant. Using QSR International's NVivo (Version 12), the researchers of this study conducted a thematic analysis to generate overarching themes and extract the relevant components of PIF. RESULTS: Five themes emerged from the study as follows: (i) domain-specific self-efficacy, (ii) role modeling and mentoring, (iii) professional socialization with peers, (iv) learning environment (LE), and (v) reflection. We considered these to be the five key contributors to dental students' PIF. CONCLUSIONS: Understanding the main concerns for students and improving the LE are critical in helping students form their professional identity. The findings of this qualitative study identified some important aspects of the dental curricula for educators to consider. These results can be used by future research studies to explore models for professional identity assessment tools that can aid in guiding students' professional identity development.

Spatiotemporal localization of periostin and its potential role in epithelial-mesenchymal transition during palatal fusion.

The medial epithelial seam (MES) between the palatal shelves degrades during palatal fusion to achieve the confluence of palatal mesenchyme. Cellular mechanisms underlying the degradation of MES have been proposed, such as apoptosis, epithelial-mesenchymal transition (EMT) and migration of medial edge epithelia (MEE). Extracellular matrix components have been shown to play an important role in EMT in many model systems. Periostin (also known as osteoblast-specific factor-2) is a secreted mesenchymal extracellular matrix component that affects the ability of cells to migrate and/or facilitates EMT during both embryonic development and pathologic conditions. In this study, we evaluated the spatiotemporal expression patterns of periostin during mouse palatal fusion by in situ hybridization and immunofluorescence. Periostin mRNA and protein were present in the palatal mesenchyme, the protein being distributed in a fine fibrillar network and in the basement membrane, but absent from the epithelium. During MES degradation, the protein was strongly expressed in the basement membrane underlying the MES and in some select MEE. Confocal microscopic analysis using an EMT marker, twist1, and an epithelial marker, cytokeratin 14, provided evidence that select MEE were undergoing EMT in association with periostin. Moreover, the major extracellular matrix molecules in basement membrane, laminin and collagen type IV were degraded earlier than periostin. The result is that select MEE establish interactions with periostin in the mesenchymal extracellular matrix, and these new cell-matrix interactions may regulate MEE transdifferentiation during palatal fusion.

The role of microbial biofilms in osteonecrosis of the jaw associated with bisphosphonate therapy.

Microbial biofilms have been observed and described in bone specimens of patients with bisphosphonate (BP)-associated osteonecrosis of the jaw (BONJ) and investigators are more recently suggesting that this condition essentially represents an osteomyelitis of the jaw clinically, with greater susceptibility in some patients on BP therapy. This article explains the role of microbial biofilms in BONJ and also discusses associated factors in the disease pathogenesis, which include BP effects on bone remodeling, anti-angiogenesis, matrix necrosis, microcracks, soft tissue toxicity, and inflammation and wound healing. Recent findings suggest a key role for microbial biofilms in the pathogenesis of BONJ; this has important therapeutic implications because biofilm organisms represent a clinical target for prevention and treatment efforts aimed at reducing the significant morbidity and costs associated with this condition.

Identification of Smad-dependent and -independent signaling with transforming growth factor-ß type 1/2 receptor inhibition in palatogenesis.

TGF-ß signaling is one of important function during palatal fusion. Three types of TGF-ß receptor (TßR1, TßR2, and TßR3) have been identified, and play essential roles in mechanisms leading to palatal fusion. However, the balance between Smad-dependent/-independent signaling during palatal fusion with inhibited TßR1/2 functions is not fully understood. The objective of this study was to investigate palatal fusion via TGF-ß signaling when TßR1 and TßR2, but not TßR3, were inhibited. In addition, the present study examined the functional balance between Smad-dependent/-independent signaling and related gene expression. Palatal organ cultures were treated with TßR1/2 inhibitor in vitro. Control palates were cultured without inhibitor. We observed histological phenotype of palatal fusion, and evaluation of expression pattern by Western blot or real time RT-PCR. Palatal organ cultures treated with the inhibitor did not fuse and the medial edge epithelium remained at embryonic 13 day +72 h in culture. The inhibitor decreased TßR1 and TßR2 expression by approximately 90%, but did not affect TßR3 expression. The expression of p-Smad2 and p-Smad3 was significantly decreased in treated palates compared with controls. The expression of p-Smad4 was slightly decreased in treated palates compared with controls. Smad-independent signaling was also affected by the inhibitor; p-ERK, p-JNK, and p-p38 expressions was significantly reduced in treated palates compared with controls. The expression of transcription factors (Runx1 and Msx1) and extracellular matrix proteins (MMP2/13) was also significantly decreased by inhibitor exposure. Treatment with TßR1/2 inhibitor altered the patterns of the Smad-dependent and -independent signaling pathways during palatal fusion.

Oral bisphosphonate use and the prevalence of osteonecrosis of the jaw: an institutional inquiry.

BACKGROUND: Initial reports of osteonecrosis of the jaw (ONJ) secondary to bisphosphonate (BP) therapy indicated that patients receiving BPs orally were at a negligible risk of developing ONJ compared with patients receiving BPs intravenously. The authors conducted a study to address a preliminary finding that ONJ secondary to oral BP therapy with alendronate sodium in a patient population at the University of Southern California was more common than previously suggested. METHODS: The authors queried an electronic medical record system to determine the number of patients with a history of alendronate use and all patients receiving alendronate who also were receiving treatment for ONJ. RESULTS: The authors identified 208 patients with a history of alendronate use. They found that nine had active ONJ and were being treated in the school's clinics. These patients represented one in 23 of the patients receiving alendronate, or approximately 4 percent of the population. CONCLUSIONS: This is the first large institutional study in the United States with respect to the epidemiology of ONJ and oral bisphosphonate use. Further studies along this line will help delineate more clearly the relationship between oral BP use and ONJ. CLINICAL IMPLICATIONS: The findings from this study indicated that even short-term oral use of alendronate led to ONJ in a subset of patients after certain dental procedures were performed. These findings have important therapeutic and preventive implications.

The Culture of Certainty in Dentistry and Its Impact on Dental Education and Practice.

With this essay, the authors encourage all dental educators to look at a common characteristic in our dental profession: the culture of certainty. They also urge educators to look beyond this culture of certainty for its impact on educational activities and clinical care.

Cell-nonautonomous induction of ovarian and uterine serous cystadenomas in mice lacking a functional Brca1 in ovarian granulosa cells.

Women with germline mutations in BRCA1 have a 40% risk of developing ovarian cancer by age 70 and are also predisposed to cancers of the fallopian tubes. Given that ovulatory activity is a strong risk factor for sporadic ovarian cancer, we hypothesized that reduced BRCA1 expression might predispose to gynecological cancers indirectly, by influencing ovarian granulosa cells. These cells secrete sex steroids that control the ovulatory cycle and influence the growth of ovarian epithelial tumors. Granulosa cells also secrete mullerian inhibiting substance (MIS), a hormone that inhibits both the formation of female reproductive organs in male embryos and the proliferation of ovarian epithelial tumor cells. We tested this hypothesis by using the Cre-lox system to inactivate the Brca1 gene in mouse ovarian granulosa cells. A truncated form of the Fsh receptor promoter served as the Cre driver. Here, we show that indeed, inactivation of the Brca1 gene in granulosa cells led to the development of cystic tumors in the ovaries and uterine horns. These tumors carried normal Brca1 alleles, supporting the view that Brca1 may influence tumor development indirectly, possibly through an effector secreted by granulosa cells.

Oral mucosal melanoma with unusual clinicopathologic features.

Oral mucosal melanoma (OMM) is an extremely rare malignancy, accounting for < 0.5% of all melanomas and all oral malignancies. The rarity of OMM, the heterogeneity in clinical and histopathologic appearances, and the paucity of molecular and genetic studies to date have limited our knowledge of the etiopathogenesis of these cancers. A 39-year-old Hispanic male presented for evaluation of a large, pigmented, plaque-like and nodular growth of the maxillary gingival and palatal mucosa. On presentation, a presumptive clinical diagnosis of mucosal melanoma was made, which was confirmed by incisional biopsy with subsequent histopathologic evaluation. Macroscopically, the morphology and highly pigmented nature of the tumor was suggestive of a rarer subtype of melanoma known as animal-type melanoma, also referred to as pigmented epithelioid melanocytoma. However, microscopically, the tumor showed histopathologic features consistent with a high-grade acral (mucosal) lentiginous melanoma with overt cytomorphologic features of malignancy in addition to showing prominent pigment synthesis resembling animal-type melanoma. A detailed search of the literature did not identify a previous report of OMM with prominent pigment synthesis resembling animal-type melanoma. Identification of melanoma subtypes has specific implications for therapeutic approach, and thus their recognition is important to successful patient management.

Identification of microbial biofilms in osteonecrosis of the jaws secondary to bisphosphonate therapy.

PURPOSE: Biofilm theory has emerged to explain the etiology of the chronic infections that have come to constitute between 65% to 80% of the microbial diseases treated by physicians in the developed world. The purpose of this article is to report for the first time the observation of multispecies microbial biofilms on affected bone in patients with osteonecrosis of the jaws (ONJ) secondary to bisphosphonate therapy. PATIENTS AND METHODS: A program has been established at the University of Southern California to monitor and evaluate patients with ONJ as a multidisciplinary collaboration between the School of Dentistry, Center for Biofilms, Center for Craniofacial Molecular Biology and the Keck School of Medicine. From this cohort, 4 patients with active ONJ who were scheduled for necessary treatment in the form of sequestrectomy gave informed consent for this study. Bone samples were evaluated using conventional histopathologic techniques and scanning electron microscopy, a technique applicable to biofilm characterization. RESULTS: Bone specimens from affected sites in all patients showed large areas occluded with biofilms comprising mainly bacteria, and occasionally yeast, embedded in extracellular polymeric substance. The number of bacterial morphotypes in the biofilms ranged from 2 to 15, and they included species from the genus Fusobacterium, bacillus, actinomyces, staphylococcus, streptococcus, Selenomonas, and 3 different types of treponemes. The yeast identified was consistent with Candida species. Co-aggregation was observed between different species within the biofilms. CONCLUSION: These findings have important clinical and therapeutic implications and may suggest a role for microbial biofilms in the disease process of ONJ.

Designing and Implementing a Competency-Based Formative Progress Assessment System at a Canadian Dental School.

Progress testing is an innovative formative assessment practice that has been found successful in many educational programs. In progress testing, one exam is given to students at regular intervals as they progress through a curriculum, allowing them to benchmark their increase in knowledge over time. The aim of this study was to assess the first two years of results of a progress testing system implemented in a Canadian dental school. This was the first time in North America a dental school had introduced progress testing. Each test form contains 200 multiple-choice questions (MCQs) to assess the cognitive knowledge base that a competent dentist should have by the end of the program. All dental students are required to complete the test in three hours. In the first three administrations, three test forms with 86 common items were administered to all DMD students. The total of 383 MCQs spanning nine domains of cognitive knowledge in dentistry were distributed among these three test forms. Each student received a test form different from the previous one in the subsequent two semesters. In the fourth administration, 299 new questions were introduced to create two test forms sharing 101 questions. Each administration occurred at the beginning of a semester. All students received individualized reports comparing their performance with their class median in each of the domains. Aggregated results from each administration were provided to the faculty. Based on analysis of students' responses to the common items in the first two administrations, progression in all domains was observed. Comparing equated results across the four administrations also showed progress. This experience suggests that introducing a progress testing assessment system for competency-based dental education has many merits. Challenges and lessons learned with this assessment are discussed.

PBL core skills faculty development workshop 2: Training faculty in group learning facilitation skills through role-modeling and role-play activities.

This report describes the second workshop in a series intended to prepare faculty for their roles in a newly instituted problem-based learning (PBL) dental program. The Facilitation of Learning workshop was designed to familiarize participants with the role of the facilitator in the small-group learning context, the skills required for facilitation, and identification of student behaviors requiring facilitator intervention. Methods included discussion of a subject-specific scenario, role-modeling of a mock student group by workshop leaders or PBL students, and role-play by participants as facilitators of the mock group. An exit survey showed the majority of participants felt the workshop goals had been met. The opportunity to observe and participate in a realistically simulated PBL group was most commonly identified as an effective workshop element by attendees, with participant discussions and opportunities for input from experienced facilitators and students (when used) also cited as effective. Participant criticisms and suggestions that will likely contribute to program enhancement notably included expressed desires for further observation and practice prior to facilitation of a PBL student learning group and availability of ongoing follow-up training and support for fledgling facilitators.

Investigating the relationship between PBL process grades and content acquisition performance in a PBL dental program.

In this study, we examined the relationship between students' problem-based learning (PBL) skills and their content acquisition as measured by traditional examinations. We conducted this investigation to evaluate the assumption that students' learning in the small group setting of PBL as evaluated by their faculty facilitators was an accurate indicator of students' learning as measured by problem analysis tests and traditional content acquisition tests. Parallel model reliability analyses were conducted to determine reliability for each year's assessment components, which included multiple choice examinations, image-based computer tests, facilitators' evaluations of students' performance in the PBL small groups, and assessments that measured the students' problem analysis and problem-solving skills. We also performed correlation tests to analyze the data. The reliability tests show that all assessment measures were consistently significant. There were predominantly significant correlations between process type assessment measures and the more traditional objective tests. When analyzed on a yearly basis, all of the correlations were significant. When analyzed on a trimester basis, all of the correlations were positive, with many being significant. The finding that the process grade revealed significant correlation with the other two assessment tools indicates that although process type evaluations may seem to be primarily subjective, they are an important metric for monitoring student progress.

PBL Core Skills Faculty Development Workshop 3: understanding PBL process assessment and feedback via scenario-based discussions, observation, and role-play.

Tutorial assessment in PBL is thought to be a valid assessment approach and is believed to exert a positive impact on the learning process. Reports, however, have demonstrated that assessment by the facilitator can be unreliable. Training of faculty to conduct this type of assessment has tended to be lacking and is a likely contributor to this inconsistency. This report describes the final in a series of foundation-building faculty development workshops focused on the instructional methodology of PBL. The PBL Assessment and Feedback workshop reported here introduced the theory and practice of conducting process-based assessment accompanied by formative feedback. Scenario-based discussions, mock group demonstration, role-modeling, and role-play were utilized as adult learning-appropriate strategies to familiarize participants with process-based assessment and feedback. Evaluation of the workshop by participants provided evidence that the majority of participants were satisfied with the methods and content of the workshop. Suggestions for additional training in these assessment methods included additional examples, practice, workshops, or observation and mentoring.

PBL core skills faculty development workshop 1: An experiential exercise with the PBL process.

This report describes the first in a series of foundation-building faculty development workshops focused on the instructional methodology of problem-based learning (PBL). The PBL Process workshop reported here introduced the learning theory topics supporting PBL and utilized an extended roleplay method to provide participants with personal experience with the PBL learning cycle. Overall, participants were satisfied with the methods and content of the workshop. A majority of survey respondents indicated that simulating a complete iteration of the PBL process was an effective way to learn about PBL. Participants expressed relatively greater difficulty understanding and performing activities related to qualitative assessment of learning processes. The workshop was developed to align with adult learning principles, and continued refinement of the workshop has enhanced the learning theory components underpinning PBL as well as the experiential aspects. These dual goals have resulted in blending the existing experiential workshop with an online distance-learning component addressing the learning theory topics relevant to PBL pedagogy.

Trends in Basic Sciences Education in Dental Schools, 1999-2016.

The purpose of this study was to examine data published over the past two decades to identify trends in the basic sciences curriculum in dental education, provide an analysis of those trends, and compare them with trends in the basic sciences curriculum in medical education. Data published from the American Dental Association (ADA) Surveys of Dental Education, American Dental Education Association (ADEA) Surveys of Dental School Seniors, and two additional surveys were examined. In large part, survey data collected focused on the structure, content, and instructional strategies used in dental education: what was taught and how. Great variability was noted in the total clock hours of instruction and the clock hours of basic sciences instruction reported by dental schools. Moreover, the participation of medical schools in the basic sciences education of dental students appears to have decreased dramatically over the past decade. Although modest progress has been made in implementing some of the curriculum changes recommended in the 1995 Institute of Medicine report such as integrated basic and clinical sciences curricula, adoption of active learning methods, and closer engagement with medical and other health professions education programs, educational effectiveness studies needed to generate data to support evidence-based approaches to curriculum reform are lacking. Overall, trends in the basic sciences curriculum in medical education were similar to those for dental education. Potential drivers of curriculum change were identified, as was recent work in other fields that should encourage reconsideration of dentistry's approach to basic sciences education. This article was written as part of the project "Advancing Dental Education in the 21st Century."

Dental Faculty Members' Pedagogic Beliefs and Curriculum Aims in Problem-Based Learning: An Exploratory Study.

The aims of this exploratory study were to explore dental faculty members' views and beliefs regarding knowledge, the dental profession, and teaching and learning and to determine how these views related to their problem-based learning (PBL) instructional practices. Prior to a PBL in dental education conference held in 2011, all attendees were invited to complete a survey focused on their pedagogical beliefs and practices in PBL. Out of a possible 55 participants, 28 responded. Additionally, during the conference, a forum was held in which preliminary survey findings were shared and participants contributed to focus group data collection. The forum results served to validate and bring deeper understanding to the survey findings. The conference participants who joined the forum (N=32) likely included some or many of the anonymous respondents to the survey, along with additional participants interested in dental educators' beliefs. The findings of the survey and follow-up forum indicated a disconnect between dental educators' reported views of knowledge and their pedagogical practices in a PBL environment. The results suggested that the degree of participants' tolerance of uncertainty in knowledge and the discrepancy between their epistemological and ontological beliefs about PBL pedagogy influenced their pedagogical choices. These findings support the idea that learner-centered, inquiry-based pedagogical approaches such as PBL may create dissonance between beliefs about knowledge and pedagogical practice that require the building of a shared understanding of and commitment to curricular goals prior to implementation to ensure success. The methods used in this study can be useful tools for faculty development in PBL programs in dental education.

Multicentric peripheral ossifying fibroma.

Peripheral ossifying fibroma (POF) is a common solitary gingival growth thought to arise from the periodontal ligament. Though the etiology of POF remains unknown, some investigators consider it an inflammatory or reactive process, while others suggest it is a neoplastic process. In this report, we present and discuss a unique case of multicentric POF, affecting the maxillary and mandibular gingiva of a 49-year-old Caucasian female with meticulous oral hygiene and routine dental care. Though biopsy samples from multiple sites revealed similar histopathologic features, consistent with POF, the fact that there was a multicentric presentation is a unique phenomenon for this lesion. Multicentric lesions presenting in the oral and maxillofacial region are not typical, but have been observed in conditions associated with known genetic mutations, such as nevoid basal cell carcinoma syndrome (multiple odontogenic keratocysts), multiple endocrine neoplasia type II (multiple neuromas), neurofibromatosis (multiple neurofibromas) and Gardner syndrome (multiple neoplasms). This case is the first one to demonstrate that there may be a multicentric variant of POF that has not been previously recognized, and given the clinical presentation and multifocal nature of disease, the lesions in this patient are likely the result of genetic mutation(s) that predisposes to gingival soft tissue overgrowths containing mineralized product.