Surface Characteristics and Microbiological Analysis of a Vat-Photopolymerization Additive-Manufacturing Dental Resin.

The wide application of additive manufacturing in dentistry implies the further investigation into oral micro-organism adhesion and biofilm formation on vat-photopolymerization (VP) dental resins. The surface characteristics and microbiological analysis of a VP dental resin, printed at resolutions of 50 µm (EG-50) and 100 µm (EG-100), were evaluated against an auto-polymerizing acrylic resin (CG). Samples were evaluated using a scanning electron microscope, a scanning white-light interferometer, and analyzed for Candida albicans (CA) and Streptococcus mutans (SM) biofilm, as well as antifungal and antimicrobial activity. EG-50 and EG-100 exhibited more irregular surfaces and statistically higher mean (Ra) and root-mean-square (rms) roughness (EG-50-Ra: 2.96 ± 0.32 µm; rms: 4.05 ± 0.43 µm/EG-100-Ra: 3.76 ± 0.58 µm; rms: 4.79 ± 0.74 µm) compared to the CG (Ra: 0.52 ± 0.36 µm; rms: 0.84 ± 0.54 µm) (p < 0.05). The biomass and extracellular matrix production by CA and SM and the metabolic activity of SM were significantly decreased in EG-50 and EG-100 compared to CG (p < 0.05). CA and SM growth was inhibited by the pure unpolymerized VP resin (48 h). EG-50 and EG-100 recorded a greater irregularity, higher surface roughness, and decreased CA and SM biofilm formation over the CG.

Stress and displacement of mini-implants and appliance in Mini-implant Assisted Rapid Palatal Expansion: analysis by finite element method.

OBJECTIVE: In this study, simulations were performed by the finite element method (FEM) to determine the tension and displacement in mini-implants and in expander appliance during rapid maxillary expansion, by varying the number and location of the mini-implants. METHODS: For the computational simulation, a three-dimensional mesh was used for the maxilla, mini-implants and expander appliance. Comparisons were made on six different Mini-implant Assisted Rapid Palatal Expander (MARPE) configurations, by varying the amount and location of mini-implants. A closed suture was design and received two activations of 0.25 mm, and an open suture had a 0.5-mm aperture that received 20 activations, also of 0.25 mm. RESULTS: For the closed suture, the maximum displacement values in the mini-implants were between 0.253 and 0.280 mm, and stress was between 1,348.9 and 2,948.2 MPa; in the expander appliance, the displacement values were between 0.256 and 0.281 mm, and stress was between 738.52 and 1,207.6 MPa. For the open suture, the maximum displacement values in the mini-implants were between 2.57 and 2.79 mm, and stress was between 5,765.3 and 10,366 MPa; in the appliance, the maximum displacements was between 2.53 and 2.89 mm, and stress was between 4,859.7 and 9,157.4 MPa. CONCLUSIONS: There were higher stress concentrations in the mini-implant than in the expander arm. In the simulations with a configuration of three mini-implants, stress overload was observed in the isolated mini-implant. Displacements of the mini-implants and arms of the appliance were similar in all simulations.

Deformation of the circummaxillary sutures during acute micro-implant assisted rapid palatal expansion and tooth-supported expansion: An ex vivo study.

INTRODUCTION: This study aimed to assess and compare the deformation that develops in the circummaxillary sutures during activation of micro-implant assisted rapid palatal expander (MARPE) and tooth-supported expander (Hyrax) s, in the rapid maxillary expansion. SETTINGS AND SAMPLE: 7 pigs Sus Scrofa received custom-made MARPE (n = 3) and Hyrax (n = 4) appliances. MATERIAL AND METHODS: The devices were activated 25 times with strain readings captured by strain gauges attached to the following regions: posterior midpalatal suture (MPS), maxilla-premaxilla suture (MPM), maxilla-zygomatic suture (MZ) and maxilla pterygoid-process suture (MPP). The intermolar distance and suture width were measured immediately before activation and at the 20th and 25th activation. ANOVA and Kruskal-Wallis test was applied. RESULTS: The MARPE group presented greater MPS displacement in all measured regions, and one of the devices produced a significant opening (1.7 mm) in the posterior region. The accumulated tension in the MPS was higher compared to the other sutures (P < .05). A MARPE animal presented higher median tension in the MPS region (294.77µÎµ) compared to all other animals except one Hyrax animal (P < .05). Regarding the median tensions of the different activation intervals, the median tension measured during the 16th to 25th activation interval in the Hyrax group was lower than that measured during the first 8 activations, in both the MPS and MZ (P < .05). CONCLUSIONS: MARPE expanders developed more constant tensions during all activations (MPS and MZ), while Hyrax showed lower tension in the 16th to 25th activation.

Are temporomandibular disorders associated with facial asymmetry? A systematic review and meta-analysis.

OBJECTIVE: To assess scientific evidence of the association between temporomandibular joint (TMJ) disorders and facial asymmetry (FA). METHODS: A systematic review was performed in accordance with the PRISMA checklist. A search strategy was developed in electronic databases including MEDLINE, Scopus, Web of Science, Virtual Health Library and Cochrane Library until January 2020. Eligibility criteria included observational studies that investigated the occurrence of FA among patients with and without signs and symptoms of TMJ disorders. Risk of bias of individual studies was analysed after study selection and data collection processes according to Fowkes and Fulton guidelines. Four meta-analyses (MA) were performed to evaluate the association between TMJ disorders and linear/angular menton deviation, subgrouping the studies into unilateral and bilateral cases. The evidence was certainty-tested using the GRADE approach. RESULTS: The search retrieved 2371 studies, 31 of which were eligible for full-text reading. Seven cross-sectional clinical studies met the eligibility criteria and were included in the qualitative synthesis, comprising a total of 621 subjects (345 with TMJ disease and 276 in control group), four of which were classified as being methodologically sound. Five studies were eligible for quantitative synthesis. Linear and angular menton deviation was greater in individuals with unilateral TMJ disorders than controls (MD = 2.41 [0.33, 4.50] P = .02; I2  = 86% and MD = 2.68 [0.99, 4.38] P = .002; I2  = 0%, respectively). CONCLUSIONS: Despite the low certainty in evidence, the present study indicated that unilateral TMJ disorders are associated with FA. However, longitudinal studies with greater certainty of evidence should be conducted to achieve a stronger estimate of this association.

Development of a calcified odontogenic hamartoma following avulsion of a permanent central incisor.

The avulsion of a permanent immature tooth is a serious condition and a real emergency in dentistry. The management of a traumatized avulsed tooth is always a challenge to the clinician. This case report concerns the development of a calcified odontogenic hamartoma after the avulsion of an immature central incisor in an eight-year-old female. The patient presented for the treatment four months after the avulsion. Her intraoral examination showed complete healing of the area but an atypical appearance of the alveolar area of the missing tooth was observed in the periapical radiograph. A new radiographic scan performed six months later revealed the formation of a radiopaque irregular structure at the cervical level of the alveolar ridge at the site of the missing tooth. Surgical removal was performed, and the histopathological examination revealed a hamartomatous proliferation of odontogenic tissue with calcification. After healing, the lateral incisor was orthodontically moved mesially and restored to resemble the central incisor. An orthodontic device was installed to improve function and aesthetics of the patient.

Details of pleasing smiles.

PURPOSE: To determine the most and least attractive smiles from a Brazilian sample and to correlate the anatomical characteristics identified in these smiles. MATERIALS AND METHODS: Orthodontists, dentists, and laypeople assessed the photographs of 86 students (66 women and 20 men), aged between 19 and 30 years, using a visual analog scale (VAS). An evaluator blinded to the results measured the esthetic composition of the eight photographs with the highest and the eight with the lowest ratings for women, and the two with the highest and the two with the lowest ratings for men. The mean and standard deviations were calculated for the descriptive analysis. RESULTS: A total of 42 anatomical smile details were identified and described, obtaining the means of the characteristics. CONCLUSIONS: The following characteristics were observed from the selected most attractive smiles: parallel smile arc, oval-shaped incisors with square-rounded edges, increase of the incisal embrasure and reduction of connector space in distal progression, display of maxillary incisors and minimum display of mandibular teeth, gingival margin of central incisors 0.5 mm coronal to the canines and 0.8 mm apical to the lateral incisors, posterior gingival display of 1.5 mm, less than 20% of buccal corridor and display of 12 teeth, and canines with -2 degrees of inclination. The most attractive smiles also had an absence of asymmetries, diastemas, black spaces, incisal plane inclination, and anterior gingival display.

Tratamento ortodôntico com extrações atípicas / Orthodontic treatment with atypical extractions

Os pré-molares são os dentes comumente extraídos com finalidade ortodôntica, e por isso, a extração de outros dentes é denominada como atípica ou não convencional. O objetivo deste artigo é apresentar uma revisão da literatura sobre tratamentos ortodônticos com essas extrações, analisando o diagnóstico e tratamento, com ênfase nas indicações e limitações. Foram discutidos e apresentados pontos relevantes das extrações de incisivos inferiores, molares, caninos e incisivos superiores. Apesar de pouco frequentes, as extrações atípicas são uma alternativa válida para correção de maloclusões. Quando bem indicados e realizados, são tratamentos que podem simplificar a mecânica ortodôntica, reduzir o tempo de tratamento e oferecer menor custo biológico comparado a outras alternativas. Entretanto, concluiu-se que os casos de extrações atípicas apresentam indicações específicas e restritas, não sendo possível estabelecer protocolos de tratamento e cada caso deve ser cuidadosamente planejado.(AU)

The premolars are commonly extracted for orthodontic purposes, and therefore the extraction of any other teeth is denominated as atypical or non-conventional. The objective of this article is to present a literature review of orthodontic treatments with atypical extractions, analyzing diagnosis and treatment and emphasizing indications and limitations. Relevant aspects regarding extractions of lower incisors, molars, canines and upper incisors were discussed. Although being uncommon, atypical extractions are a valid alternative for correcting malocclusions. When well indicated and performed, they can simplify orthodontic mechanics, reduce treatment time, and offer lower biological cost compared to other alternatives. Nevertheless, it may be concluded that cases of atypical extractions present specific and restricted indications and it is not possible to establish treatment protocols as each case must be planned carefully.(AU)

Comparação da deformação e degradação de força entre elásticos látex e não látex – estudo in vitro / Comparison of deformation and force decay between latex and non latex elastics – in vitro study

A Ortodontia, desde que surgiu como especialidade, faz uso de elásticos para correção das más oclusões, sendo impossível imaginar um tratamento ortodôntico corretivo sem essa ferramenta. O objetivo deste estudo foi testar a hipótese que elásticos 1/8”, 3/16”, 1/4” e 5/16” não látex sofrem maior deformação e degradação que elásticos látex de mesmo diâmetro. O modelo experimental foi constituído de placa de acrílico contendo bráquetes ortodônticos e os elásticos foram inseridos no bráquete do canino e segundo pré-molar. O diâmetro interno e a magnitude de força de cada elástico foram mensurados nos intervalos de 0, 24 horas, 72 horas e 504 horas. A amostra foi armazenada em saliva artificial em temperatura ambiente durante todo período de avaliação e os elásticos foram removidos e novamente inseridos três vezes ao dia para simular as trocas realizadas pelo paciente. O diâmetro interno e a magnitude de força entre os elásticos látex e não látex nos diferentes períodos experimentais foram comparados pela ANOVA de medidas repetidas e pelo pós-teste de Bonferroni. A deformação dos elásticos de látex foi menor e mais uniforme do que os de não látex. Elásticos não látex apresentaram maior degradação de força do que os de látex em todos os períodos.

Since Orthodontics emerged as specialty elastics are used for malocclusion correction. It is impossible to imagine a corrective treatment without this tool. The objective of this study was to test the hypothesis that 1/8”, 3/16”, 1/4” and 5/16 non-latex intermaxillary elastics suffer bigger deformation and degradation over time than latex elastics of the same diameter. The experimental model consisted of an acrylic plate containing orthodontic brackets and the elastics were inserted in brackets of the canine and second bicuspid. Internal diameter and magnitude of force of each elastic were measured at intervals from 24 hours, 72 hours, and 504 hours. The sample was stored in artificial saliva at room temperature throughout the evaluation period and the elastics were removed and reinstalled at the plates three times daily in order to simulate the changes made by the patient. The internal diameter and magnitude of force between the non-latex and latex elastics at the different periods were compared by ANOVA with repeated measures and the Bonferroni post-test. The deformation of the latex elastics was lower and more uniform than those of non-latex. The non-latex elastics showed higher force degradation than latex in all periods.

Comparison of two scales for evaluation of smile and dental attractiveness.

OBJECTIVE: To compare the visual analogue scale (VAS) and the simplified Q-sort method used to investigate the highest level of agreement among dentists, orthodontists and laypeople when assessing smile and dental attractiveness. MATERIAL AND METHODS: An album containing 258 photos of 86 individuals with their lips at rest, a slight and broad smile, was assessed by 25 dentists (general clinicians and various specialties), 23 orthodontists and 27 laypeople with regard to smile and dental attractiveness. To this end, both VAS and simplified Q-sort method were used. Agreements were calculated by intraclass correlation coefficient (ICC). RESULTS: For the single measurement between the VAS method and the simplified Q-sort method, all simplified Q-sort rates were higher in all groups. The simplified Q-sort method results ranged between 0.42 and 0.49 while those of the VAS method varied between 0.37 and 0.42. The simplified Q-sort method also presented higher mean measurement values (0.95 and 0.96) in comparison to VAS (0.94 and 0.95). CONCLUSIONS: Both scales may be considered reliable for evaluating smile and dental attractiveness; however, the simplified Q-Sort method presented slightly higher values than the VAS method.

Comparison of two scales for evaluation of smile and dental attractiveness

OBJECTIVE: To compare the visual analogue scale (VAS) and the simplified Q-sort method used to investigate the highest level of agreement among dentists, orthodontists and laypeople when assessing smile and dental attractiveness. MATERIAL AND METHODS: An album containing 258 photos of 86 individuals with their lips at rest, a slight and broad smile, was assessed by 25 dentists (general clinicians and various specialties), 23 orthodontists and 27 laypeople with regard to smile and dental attractiveness. To this end, both VAS and simplified Q-sort method were used. Agreements were calculated by intraclass correlation coefficient (ICC). RESULTS: For the single measurement between the VAS method and the simplified Q-sort method, all simplified Q-sort rates were higher in all groups. The simplified Q-sort method results ranged between 0.42 and 0.49 while those of the VAS method varied between 0.37 and 0.42. The simplified Q-sort method also presented higher mean measurement values (0.95 and 0.96) in comparison to VAS (0.94 and 0.95). CONCLUSIONS: Both scales may be considered reliable for evaluating smile and dental attractiveness; however, the simplified Q-Sort method presented slightly higher values than the VAS method. .

OBJETIVO: comparar a escala visual analógica (EVA) e o método Q-sort simplificado quanto à maior concordância nas avaliações entre cirurgiões-dentistas, ortodontistas e leigos em atratividade dentária e do sorriso. MÉTODOS: 258 fotografias, provenientes de 86 indivíduos, fotografados com os lábios em repouso, sorriso leve e sorriso amplo, foram avaliadas quanto à atratividade dentária e do sorriso por meio da EVA e do Q-sort simplificado por 25 cirurgiões-dentistas (clínicos gerais e especialidades diversas), 23 Ortodontistas e 27 leigos. As concordâncias foram calculadas pelo Coeficiente de Correlação Intraclasse (ICC). RESULTADOS: para medida única entre a EVA e o método Q-sort simplificado, todas as taxas do Q-sort simplificado foram maiores em todos os grupos. O resultado do Q-sort simplificado variou entre 0,42 e 0,49, e da EVA entre 0,37 e 0,42. O Q-sort simplificado também apresentou valores de medida média superiores (0,95 e 0,96) em relação à EVA (0,94 e 0,95). CONCLUSÃO: pode-se considerar que ambas as escalas são confiáveis para avaliação da atratividade dentária e do sorriso; porém, o método Q-sort simplificado apresentou valores ligeiramente maiores que os da EVA. .