Adenomatoid odontogenic tumor: Features of ameloblastic-like epithelial cells differentiation, secretion, and the nature of tumor cells products.

BACKGROUND: This study aimed to investigate the differentiation of ameloblastic-like cells and the nature of the secreted eosinophilic materials in adenomatoid odontogenic tumors. METHODS: We studied histological and immunohistochemical characteristics of 20 cases using: cytokeratins 14 and 19, amelogenin, collagen I, laminin, vimentin, and CD34. RESULTS: Rosette cells differentiated into ameloblastic-like cells positioned face-to-face, displaying collagen I-positive material between them. Epithelial cells of the rosettes can differentiate into ameloblastic-like cells. This phenomenon probably occurs due to an induction phenomenon between these cells. The secretion of collagen I is probably a brief event. Amelogenin-positive areas were interspersed by epithelial cells in the lace-like areas, outside the rosettes and distant from the ameloblastic-like cells. CONCLUSIONS: There are at least two types of eosinophilic material in different areas within the tumor, one in the rosette and solid areas and another in lace-like areas. The secreted eosinophilic material in the rosettes and solid areas is probably a product of well-differentiated ameloblastic-like cells. It is positive for collagen I and negative for amelogenin, whereas some eosinophilic materials in the lace-like areas are positive for amelogenin. We hypothesize that the latter eosinophilic material could be a product of odontogenic cuboidal epithelial or intermediate stratum-like epithelial cells.

Artificial Intelligence for Detecting Cephalometric Landmarks: A Systematic Review and Meta-analysis.

Using computer vision through artificial intelligence (AI) is one of the main technological advances in dentistry. However, the existing literature on the practical application of AI for detecting cephalometric landmarks of orthodontic interest in digital images is heterogeneous, and there is no consensus regarding accuracy and precision. Thus, this review evaluated the use of artificial intelligence for detecting cephalometric landmarks in digital imaging examinations and compared it to manual annotation of landmarks. An electronic search was performed in nine databases to find studies that analyzed the detection of cephalometric landmarks in digital imaging examinations with AI and manual landmarking. Two reviewers selected the studies, extracted the data, and assessed the risk of bias using QUADAS-2. Random-effects meta-analyses determined the agreement and precision of AI compared to manual detection at a 95% confidence interval. The electronic search located 7410 studies, of which 40 were included. Only three studies presented a low risk of bias for all domains evaluated. The meta-analysis showed AI agreement rates of 79% (95% CI: 76-82%, I2 = 99%) and 90% (95% CI: 87-92%, I2 = 99%) for the thresholds of 2 and 3 mm, respectively, with a mean divergence of 2.05 (95% CI: 1.41-2.69, I2 = 10%) compared to manual landmarking. The menton cephalometric landmark showed the lowest divergence between both methods (SMD, 1.17; 95% CI, 0.82; 1.53; I2 = 0%). Based on very low certainty of evidence, the application of AI was promising for automatically detecting cephalometric landmarks, but further studies should focus on testing its strength and validity in different samples.

Digital anatomy table in teaching-learning process of the temporomandibular joint anatomy.

INTRODUCTION: The use of teaching resources and digital objects has gradually been incorporated into dental schools. This study aimed to evaluate the digital anatomy table in teaching-learning process of the temporomandibular joint (TMJ) anatomy and the student's perception regarding this resource. MATERIALS AND METHODS: A cross-sectional study was conducted on 41 undergraduate dental students. Knowledge assessment tests were applied at different time intervals: before and after the TMJ theoretical class, after the practical class on prosected specimens and after the use of digital anatomy table. The medians of the scores obtained in the three groups (theoretical class, practical class and digital table) were descriptively analysed and submitted to Wilcoxon, Kruskal-Wallis and Student-Newman-Keuls statistical tests. The perception survey was conducted at the end of the study. RESULTS: When the teaching strategies were compared amongst each other, the medians of the scores with the digital anatomy table were significantly higher than after the theoretical and practical classes. At the end of the research, there were no differences amongst the three groups (theoretical class, practical class and digital table). Regarding the perception, the majority of the students reported that the digital anatomy table helped them to understand the content of the theoretical class. CONCLUSION: It was concluded that learning with the use of the digital anatomy table did not increase the knowledge of dental students with respect to the TMJ anatomy. The students' perceptions of the digital anatomy table were positive and that it could be used as an additional resource in the teaching-learning process.

Implant insertion angle and depth: Peri-implant bone stress analysis by the finite element method.

BACKGROUND: The study aimed to assess the influence of different implant insertion angles and depths on the stresses produced on the surface of peri-implant bone tissue under axial and oblique loading. MATERIAL AND METHODS: The entire study followed the recommendations of the Checklist for Reporting In-vitro Studies (CRIS). The implant was placed in the region of element 36, according to the following models: M1 (0 mm / 0°); M2 (0 mm / 17°); M3 (0 mm / 30°); M4 (2 mm / 0°); M5 (2 mm / 17°); M6 (2 mm / 30°). The models were subjected to loading, with intensity of 100 N. The stress assessment followed the Mohr-Coulomb criterion and qualitative and quantitative analyses were performed. RESULTS: Angled implants and installed below the bone crest produced the highest stresses on the cortical bone, and the axial load presented the highest stress peaks on the buccal side of implants perpendicular to the bone crest. Regardless of the type of load (axial or oblique), inclined implants presented the highest stress peaks on the lingual side of the cortical bone. CONCLUSIONS: Implants installed perpendicular to and with a prosthetic platform at bone crest height provided the lowest stresses to peri-implant bone tissue under both axial and oblique loading. Key words:Finite element analysis, dental implants, axial loading, biomechanical phenomena.

Effectiveness of anesthetic solutions for pain control in lower third molar extraction surgeries: a systematic review of randomized clinical trials with network meta-analysis.

OBJECTIVE: To assess the effectiveness of different anesthetic solutions for pain control immediately after the extraction of lower third molars. METHODS: Nine databases were used to identify randomized clinical trials, without restriction of language or year of publication. The "JBI Critical Appraisal Tools for Systematic Reviews" was used to assess the risk of bias in the studies. The network meta-analysis was performed to compare the effectiveness of different anesthetics to control the pain immediately after the surgery of lower third molars, using the standardized mean difference (SMD) as the effect estimate. The GRADE approach was used to assess the certainty of evidence. RESULTS: The search presented 13,739 initial results, from which 45 met the eligibility criteria and presented low to moderate risk of bias. Thirteen studies were included in the meta-analysis. The 2% lidocaine + clonidine presented the lowest pain scores (SMD = - 1.44; - 2.72 to - 0.16) compared to 4% articaine + adrenaline, followed by 0.5% bupivacaine + adrenaline (SMD = - 1.36; - 2.13 to - 0.59). The certainty of evidence varied between very low to moderate. CONCLUSION: 2% lidocaine + clonidine and 0.5% bupivacaine + adrenaline were the anesthetics with the highest probability for pain control immediately after the surgical procedure of removing impacted lower third molars. CLINICAL SIGNIFICANCE: The use of an adequate anesthetic with effective pain control can contribute to a more comfortable postoperative period.

Effect of Hyaluronic Acid and Poly-L-Lactic Acid Dermal Fillers on Collagen Synthesis: An in vitro and in vivo Study.

PURPOSE: Skin ageing is marked by structural and functional changes in epidermis and dermis, which result clinically in wrinkles, loss of elasticity, and rough-textured appearance. In this context, different dermal fillers have been used to overcome these negative effects associated with skin ageing, such as hyaluronic acid (HA) and poly-L-lactic acid (PLLA). Despite their low immunogenicity, these materials can cause an inflammatory reaction after application. MATERIALS AND METHODS: Considering high demand of HA and PLLA as filler material, this study aimed to evaluate their in vitro and in vivo effects. For the in vitro study, human dermal fibroblast cell cultures were supplemented with HA or PLLA for 24, 48, and 72 h. The following parameters were assayed: 1) cell proliferation, 2) cell viability, and 3) quantification of type I collagen by ELISA. For the in vivo study, HA or PLLA was injected in the dermis of Wistar rats and the tissues were collected after 15, 30, and 60 days for histologic evaluation and for quantification of type I collagen by Western blotting. The quantitative data were statistically analyzed using an ANOVA two-way. The significance level was set at 5%. RESULTS: At 72 h, high cell proliferation was observed for HA compared to control (p<0.05). Cultures exposed to PLLA exhibited a reduction in both cell proliferation and viability compared to control in all time points (p<0.05). Type I collagen expression was greater in cultures exposed to HA or PLLA compared to control (p<0.05). Histologic analysis showed the presence of multinucleated cells only in the PLLA group in all experimental time points. Western blotting analysis revealed high content of type I collagen in HA compared to PLLA (p<0.05). CONCLUSION: The present study addresses a potentially unfavorable effect of dermal PLLA filler on the fibroblast phenotype, with possible clinical complications, unlike HA.

Liposomal butamben gel formulations: toxicity assays and topical anesthesia in an animal model.

The aim of this study was to evaluate the in vitro cytotoxicity and the in vivo analgesic effect and local toxicity of the local anesthetic butamben (BTB) encapsulated in conventional or elastic liposomes incorporated in gel formulations. The results showed that both gel formulations of liposomal BTB reduced the cytotoxicity (p < 0.001; one-way ANOVA/Tukey's test) and increased the topical analgesic effect (p < 0.05; one-way ANOVA/Tukey's test) of butamben, compared to plain BTB gel. The gel formulations presented good rheological properties, and stability assays detected no differences in physicochemical stability up to 30 d after preparation. Moreover, histological assessment revealed no morphological changes in rat skin after application of any of the gel formulations tested.

Lymphotoxin-Alpha Gene Polymorphism +252A/G (rs909253, A/G) Is Associated with Susceptibility to Chronic Periodontitis: A Pilot Study.

Background. Periodontal disease leading to clinical findings such as increased periodontal probing depth involves a complex interaction between invading pathogenic microorganisms and the patient's immune system. Lymphotoxin alpha (LT-α) is a potent multifunctional immune modulator that contributes toward susceptibility to immune regulation disorders, including periodontal disease. Objective. In this study, we tested the hypothesis that chronic periodontitis (CP) is associated with polymorphisms of the LT-α gene. Materials and Methods. A total of 126 subjects, 44 healthy subjects, and 82 subjects with CP, were evaluated for periodontal disease by measuring clinical attachment loss and separation. Samples of epithelial cells were obtained for DNA analysis by scraping of the buccal mucosa. The LT-α gene was analyzed by polymerase chain reaction followed by endonuclease digestion with NcoI to analyze restriction fragment length polymorphisms. Results. The LT-α gene (+252A/G) polymorphism was associated with CP. LT-α allele frequencies were significantly different (P = 0.0019) between patients with CP and healthy individuals, with an odds ratio of 2.67 for patients with CP with the G allele. Conclusions. These findings suggest the LT-α gene genotype is a risk indicator for susceptibility to chronic periodontal disease in the Brazilian population studied.

Polymorphisms in the vitamin D receptor gene are associated with periodontal disease.

BACKGROUND: Genetic polymorphisms in the vitamin D receptor (VDR) gene are associated with bone homeostasis and diseases in which bone loss is a cardinal sign. The aim of this study was to determine whether chronic periodontal disease in a Brazilian population is associated with polymorphisms in the VDR gene. METHODS: Clinical examination and recordings of probing depth and clinical attachment level were performed in 113 unrelated adults who were divided into two groups: 44 healthy individuals (control group) and 69 subjects with chronic periodontitis (CP). DNA was obtained from the subjects' epithelial cells by scraping the buccal mucosa. Two polymorphisms in the VDR gene were analyzed by polymerase chain reaction, followed by Taql and BsmI restriction endonuclease digestion. RESULTS: Frequencies of VDR/TaqI and VDR/BsmI showed significant differences between the control group and the CP group (P < 0.05). The "Tb" haplotype was prevalent in the control group (43.2%), and the "TB" haplotype in the CP group (36.6%). The "TB" haplotype seemed to increase susceptibility to periodontal disease (odds ratio [OR] = 2.19). The heterozygous haplotype "TB/tb" was predominant in the CP group (OR = 4.32; P = 0.005). CONCLUSIONS: TaqI and BsmI polymorphisms of the VDR gene are associated with clinical attachment loss due to periodontal disease in a Brazilian population. These findings suggest that VDR genotype might be a risk indicator for susceptibility to chronic periodontitis.