Time to Recurrence of Ameloblastoma and Associated Factors in a Multi-institutional Black Patient Cohort.

Ameloblastoma is a highly recurrent odontogenic neoplasm with variable global distribution. However, impact of race and ethnicity on ameloblastoma recurrence are still unclear. The primary aim of this study was to assess duration of time between primary and recurrent ameloblastomas in a predominantly Black multi-institutional patient cohort and secondarily to determine whether recurrent ameloblastomas are more readily discovered when clinically-symptomatic rather than by radiographic surveillance. A retrospective cross-sectional design was used to evaluate demographic, clinical, and pathological information on recurrent ameloblastomas patients. Outcome variable was time to recurrence, determined as period between the diagnosis of primary and recurrent ameloblastomas. We assessed associations between outcome variable and race, time lapse between primary and recurrent ameloblastomas and clinical symptoms of recurrent ameloblastomas at time of diagnosis. Among 115 recurrent ameloblastomas identified, 90.5% occurred in adults, 91.3% in Blacks, and similarly, 91.3% were conventional ameloblastomas. About 41% affected the posterior mandible. 93.9% were clinically symptomatic at time of presentation while 6.1% non-symptomatic lesions were discovered by routine diagnostic radiology. Median time to presentation of recurrent tumor was significantly longer in females (90 months, p = 0.016) and clinically symptomatic group of ameloblastoma patients (75 months, p = 0.023). Ameloblastoma recurrence was distinctively high in Black patients, occurred faster in males than females and was located mostly in the posterior mandible. Concomitant with delayed access to healthcare of Black individuals, routine post-surgical follow-up is essential because time lag between primary and recurrence tumors was longer in clinically symptomatic ameloblastomas at the time of diagnosis.

Comparison of diagnostic methods for detection of BRAFV600E mutation in ameloblastoma.

BACKGROUND: Ameloblastoma is an aggressively growing, highly recurrent odontogenic jaw tumor. Its association with BRAFV600E mutation is an indication for BRAFV00E-inhibitor therapy The study objective was to identify a sensitive low-cost test for BRAFV600E-positive ameloblastoma. We hypothesized that immunohistochemical staining of formalin-fixed paraffin-embedded tissues for BRAFV600E mutation is a low-cost surrogate for BRAFV600E gene sequencing when laboratory resources are inadequate for molecular testing. METHODS: Tissues from 40 ameloblastoma samples were retrieved from either formalin-fixed paraffin-embedded blocks, RNAlater™ stabilization solution or samples inadvertently pre-fixed in formalin before transfer to RNAlater™. BRAFV600E mutation was assessed by Direct Sanger sequencing, Amplification Refractory Mutation System-PCR and immunohistochemistry (IHC). RESULTS: BRAFV600E mutation was detected by IHC, Amplification Refractory Mutation System-PCR and Direct Sanger sequencing in 93.33%, 52.5% and 30% of samples respectively. Considering Direct Sanger sequencing as standard BRAFV600E detection method, there was significant difference between the three detection methods (𝜒2 (2) = 31.34, p < 0.0001). Sensitivity and specificity of IHC were 0.8 (95% CI: 0.64-0.90) and 0.9 (95% CI: 0.75-0.99) respectively, while positive predictive value and negative predictive value (NPV) were 0.9 and 0.8 (Fischer's test, p < 0.0001) respectively. Sensitivity and specificity of Amplification Refractory Mutation System-PCR detection method were 0.7 (95% CI: 0.53-0.80) and 0.9 (95% CI = 0.67-0.98) respectively, while PPV and NPV were 0.9 and 0.6 respectively (Fischer's test, p < 0.0001). CONCLUSION: Low-cost and less vulnerability of IHC to tissue quality make it a viable surrogate test for BRAFV600E detection in ameloblastoma. Sequential dual IHC and molecular testing for BRAFV600E will reduce equivocal results that could exclude some patients from BRAFV600E-inhibitor therapies.

Managing the phase-down of amalgam amongst Nigerian dental professionals and students: A national survey.

BACKGROUND: Amalgam is one of the most reliable dental restorative materials. Health and environmental concerns associated with the mercury content of amalgam have necessitated an amalgam phase-down in clinical practice. OBJECTIVES: This study investigated the level of awareness and preparedness for the planned amalgam phase-down recommended by the Minamata Convention amongst Nigerian dental students and dentists. METHODS: This cross-sectional national survey was performed across all geopolitical zones of Nigeria. Data regarding awareness, practice and level of preparedness for amalgam phase-down were obtained using a questionnaire that was distributed amongst clinical dental students and dentists of different cadres, who routinely place dental restorations, in public and private practice. The questionnaires were administered online or were hand delivered. Data were analysed using the chi-square test and Spearman's rank correlation coefficient. A p value ≤ 0.05 was considered statistically significant. RESULTS: Notably, 845 dental students and dentists participated in the survey. Mean age (±standard deviation) of participants was 30.15 ± 7.67 years, 33.8% were students, and 66.2% were dentists (most dentists [77.1%] were employed at public hospitals). A significant percentage of respondents had poor knowledge of the Minamata Convention (87.7%) and lacked training in the use of alternatives to amalgam (72.0%). Amalgam continues to be commonly used by 39.1% and 31.3% of dental students and dentists, respectively. Only 4.7% of the respondents admitted to following good amalgam phase-down practices. Awareness (P = 0.013) and amalgam phase-down practices (P = 0.011) were significantly higher amongst dentists than amongst dental students. CONCLUSION: We observed low levels of awareness regarding the Minamata Convention, amalgam phase-down, mercury hygiene practices and training in alternatives to amalgam use amongst Nigerian dental professionals and students.

Enhanced basal autophagy supports ameloblastoma-derived cell survival and reactivation.

OBJECTIVES: Ameloblastoma is an aggressive odontogenic jaw neoplasm. Its unlimited growth confers high potential for malignant transformation and recurrence. It is unclear why ameloblastoma is highly recurrent despite surgical resection with a wide margin of normal tissue. While canonical autophagy can be used to degrade and eliminate damaged cellular components, it is also a protective mechanism that provides energy and vital metabolites for cell survival. We used ameloblastoma-derived cells to test the hypothesis that autophagic processes play a role in survival and reactivation of ameloblastoma. METHODS: Primary epithelial (EP-AMCs) and mesenchymal (MS-AMCs) ameloblastoma-derived cells were established from tissue samples of solid multicystic ameloblastoma. Clonogenic capacity and basal autophagic capacity were assessed in ameloblastoma-derived cells relative to human odontoma-derived cells (HODCs) and maxilla-mesenchymal stem cells (MX-MSCs). Ability of ameloblastoma-derived cells to survive and form new ameloblastoma was assessed in mouse tumor xenografts. RESULTS: EP-AMCs were highly clonogenic (p < 0.0001) and demonstrated enhanced basal levels of autophagic proteins microtubule-associated protein 1-light chain 3 (LC3) (p < 0.01), p62 (Sequestosome 1, SQSTM1) (p < 0.01), and the LC3-adapter, melanoregulin (MREG) (p < 0.05) relative to controls. EP-AMCs xenografts regenerated solid ameloblastoma-like tumor with histological features of columnar ameloblast-like cells, loose stellate reticulum-like cells and regions of cystic degeneration characteristic of follicular variant of solid multicystic ameloblastoma. The xenografts also displayed stromal epithelial invaginations strongly reactive to LC3 and p62 suggestive of epithelial-mesenchymal transition and neoplastic odontogenic epithelium. CONCLUSIONS: EP-AMCs exhibit altered autophagic processes that can support survival and recurrence of post-surgical ameloblastoma cells.

Spontaneous Regeneration of the Mandible: An Institutional Audit of Regenerated Bone and Osteocompetent Periosteum.

PURPOSE: Childhood mandibular lesions are frequently benign; this allows for a conservative surgical approach to their management. Two of the most common approaches for reconstruction of acquired mandibular defects in adolescents are vascularized and nonvascularized osseous flaps or grafts. A third, less commonly used treatment option often used in developing parts of the world that some Western centers are considering as part of their treatment algorithm is spontaneous bone regeneration. This study reports on the authors' experiences with spontaneous bone formation of the resected young mandible. It also attempts to quantify any relation between spontaneous bone regeneration and an aging osteocompetent periosteum. PATIENTS AND METHODS: This was a retrospective study based on consecutive data collated from records of the oral and maxillofacial surgery departments from 2 tertiary institutions. Eligible patients were no older than 18 years and had benign mandibular neoplasms. The surgical procedure was mandibulectomy with subperiosteal dissection and intermaxillary fixation. Regenerated bone evaluation was by clinical examination and periodic panoramic radiographs. RESULTS: Sixteen consecutive cases with mandibular lesions were seen at the 2 institutions, 8 of which met the inclusion criteria. The average age was 10.75 years. The predominant pathology was unicystic ameloblastoma. All cases exhibited spontaneous bone regeneration, with 2 cases exhibiting "incomplete" bone regeneration. CONCLUSION: Immediate reconstruction can be delayed to allow for spontaneous bone regeneration of defects in young patients. In the absence of regeneration, secondary reconstruction can be considered. Although the literature reports more young patients with bone regeneration than adults, increasing age during childhood and adolescence might not necessarily indicate a decrease in periosteal bone-regenerating potential.

Preoperative administration of 0.2% chlorhexidine mouthrinse reduces the risk of bacteraemia associated with intra-alveolar tooth extraction.

The aim of the study was to investigate the effect of preoperative 0.2% chlorhexidine mouthwash on the risk of bacteraemia following routine intra-alveolar tooth extraction. The study was a randomized controlled clinical study of 101 subjects who underwent intra-alveolar dental extractions under local anaesthesia. Subjects were randomly assigned to either chlorhexidine or a control group. The chlorhexidine group had 0.2% chlorhexidine mouthwash administered for 1 min before any dental manipulation, and the control group had a mouthrinse of sterile water. Blood samples were collected at baseline, 1 min and 15 min after the dental extractions. Subculture and further identification of the isolated bacteria were performed by conventional microbiological techniques. There was a statistically significant difference in the incidence of bacteraemia between the control group (52.4%) and chlorhexidine group (27.1%) (P = 0.012). Bacteraemia was most frequently detected at 1 min after extraction (33.3%). Of the 30 subjects who had positive blood culture at 1 min, bacteraemia persisted in 8 (26.7%) of the subjects after 15 min. Bacteria isolated included Staphylococcus aureus, Actinomycetes naesulendi, Prevotella species, Streptococcus spp., and Acinetobacter iwoffii. Routine use of 0.20% chlorhexidine mouthwash before dental extraction is recommended to reduce the risk of bacteraemia following tooth extraction.

Knowledge, attitude, and practice of dental implantology in Nigeria.

AIM: The purpose of this study was to assess the knowledge, attitude, and practice of dental implantology among dentists practicing in Nigeria. MATERIALS: Self-administered questionnaires to assess the knowledge, practice, and attitude of dental implantology were sent to dentists practicing in all the 6 geopolitical zones of Nigeria (i.e., all tertiary dental institutions, and selected general and private hospitals within the zones). Data collected were analyzed and presented in descriptive and tabular forms. RESULTS: The response rate was 77%. Only 2 (1.3%) of the respondents claimed to have employed implant(s) for dental restoration in their practice, while 152 respondents (98.7%) have never used implants as a method of tooth/teeth restoration. Of the latter, 46.1% have suggested implants for full/partial denture patients, 31.8% have suggested dental implants to patients needing single-tooth replacement, and 89.6% were ready for dental implant placement if equipment and materials for dental implants backed up with adequate training were provided. Of respondents, 83.1% also believed that implantology is a multidisciplinary approach, and 42.9% rated implants as the best option for dental restoration. CONCLUSIONS: The practice of implant dentistry is presently very low in Nigeria. Clearly, there is a need for dental implant education for Nigerian dentists to increase their knowledge and proficiency in dental implant dentistry. In addition, all efforts should be made to include implant education and practice in dental curricula in undergraduate and postgraduate institutions in Nigeria.

Ameloblastoma in Nigerian children and adolescents: a review of 79 cases.

PURPOSE: To descriptively review the clinicopathologic presentation and management of ameloblastoma in Nigerian children and adolescents and compare this with previous reports in the literature. METHODS AND MATERIALS: Data were collected from the case files of patients managed at 4 tertiary referral centers in Nigeria. RESULTS: Out of a total of 360 patients with a diagnosis of ameloblastoma, 79 were under 20 years of age at presentation (21.9%). Only 2.5% of the patients were under 10 years of age. The male-female ratio was 1.3 to 1 with a peak age incidence of 15 years in males and 17 years in females. All the tumors were intraosseous and the majority (94.9%) were situated in the mandible. The most common morphologic type was solid multicystic ameloblastoma (82.3%). The majority (66.2%) had a multilocular radiographic presentation. In most patients (57.3%), the symphysial region of the mandible was involved by the tumor. However, exclusively anterior tumors constituted only 15.2% of the cases, while tumors involving anterior and posterior jaw regions constituted 41.1%. Resection was the predominant (72.2%) form of surgical management. CONCLUSION: Ameloblastoma in Nigerian children and adolescents exhibit some peculiar clinical features: these include the predominance of males, and of the solid multicystic morphologic type. In addition, there is site predilection for the symphysial region of the mandible. Radical surgical resection remains the predominant form of treatment. Therefore, varying degrees of interference with facial growth will be present in these children.