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ObjectiveThe objective this work was to assess the friction coefficient between brackets and wires of different materials under conditions simulating the oral environment.Material and MethodsStainless steel (SS) and titanium-molybdenum alloy (TMA) wires of 0.019x0.025-in diameter (American Orthodontics) and polycarbonate bracket (American Orthodontics), ceramic bracket (American Orthodontics), and metal bracket (3M Unitek) with slots of 0.022x0.030-in were used. The friction coefficient was assessed by means of mechanical traction with the system immersed in artificial saliva. The mean roughness of both wire surface and bracket slots was evaluated by using a surface profilometer.ResultsThe system using TMA wire and polycarbonate bracket had the highest roughness (p<0.05). SS wire with ceramic bracket had the highest friction coefficient, whereas the use of metallic bracket yielded the lowest (p<0.05). However, it was observed a statistically significant difference in the system using TMA wire and ceramic bracket compared to that using TMA wire and polycarbonate bracket (p=0.038).ConclusionCeramic brackets in association with SS wire should be judiciously used, since this system showed a high friction coefficient.

O termo epidermólise bolhosa descreve um grupo variado de doenças hereditárias, crônicas, não inflamatórias, epiteliais e da mucosa, que são caracterizadas por excepcional fragilidade e reduzida resistência após trauma moderado. Esta doença é classificada em forma simples, juncional ou distrófica, com pelo menos 23 subtipos, e é uma doença rara que afeta toda a população, qualquer grupo racial e igualmente homens e mulheres. OBJETIVO: os autores relatam problemas sistêmicos e bucais associados à epidermólise bolhosa, norteando atitudes clínicas multidisciplinares quando o paciente necessita de tratamento ortodôntico.

Orthodontic tooth movement (OTM) is a dynamic process of bone modeling involving osteoclast-driven resorption on the compression side. Consequently, to estimate the influence of various situations on tooth movement, experimental studies need to analyze this cell. Objectives The aim of this study was to test and validate a new method for evaluating osteoclastic activity stimulated by mechanical loading based on the fractal analysis of the periodontal ligament (PDL)-bone interface.Material and Methods The mandibular right first molars of 14 rabbits were tipped mesially by a coil spring exerting a constant force of 85 cN. To evaluate the actual influence of osteoclasts on fractal dimension of bone surface, alendronate (3 mg/Kg) was injected weekly in seven of those rabbits. After 21 days, the animals were killed and their jaws were processed for histological evaluation. Osteoclast counts and fractal analysis (by the box counting method) of the PDL-bone interface were performed in histological sections of the right and left sides of the mandible.Results An increase in the number of osteoclasts and in fractal dimension after OTM only happened when alendronate was not administered. Strong correlation was found between the number of osteoclasts and fractal dimension.Conclusions Our results suggest that osteoclastic activity leads to an increase in bone surface irregularity, which can be quantified by its fractal dimension. This makes fractal analysis by the box counting method a potential tool for the assessment of osteoclastic activity on bone surfaces in microscopic examination.

Bone formation is essential to orthodontic tooth movement and bone is formed by collagen. To analyze the collagen maturation process on bone matrix neoformed under nonsteroidal and steroidal treatment during orthodontic tooth movement by polarized microscopy, male Wistar rats (n = 90) were randomly divided into three groups (n = 30): C (control), NSAID (potassium diclofenac) and SAID (disodic phosphate dexamethasone). The animals of the C group received 0.9% saline solution; NSAID group received 5 mg/kg potassium diclofenac (CATAFLAM®); and SAID group received 2 mg/kg phosphate dissodic dexamethasone (DEXANIL®). Animals were sacrificed 3, 7 or 14 days after the placement of orthodontic appliances and the upper first molars were processed histologically and stained with picrosirius. Bone formation was evaluated under polarized light microscopy and 4.5 Image Pro-Plus® software calculated the percentage of immature/mature collagen present in the groups. On the third days after force application, SAID and NSAID groups showed greater proportion of immature collagen than C group. On the seventh and fourteenth days, there was a lower proportion of mature collagen only in the SAID group (P < 0.001). These data demonstrate that dexamethasone delays the collagen maturation process in established bone matrix.

ObjectiveTo assess scientific evidence of the association between temporomandibular joint (TMJ) disorders and facial asymmetry (FA).MethodsA 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.ResultsThe 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).ConclusionsDespite 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.

The aim of this study was to evaluate, by histological analysis, the effect of growth hormone (GH) on periodontal ligament and alveolar bone during experimental tooth movement in rats. Eighty male Wistar rats divided into control (C) and experimental (E) groups were examined after 3, 7, 14 and 21 days under controlled climate conditions. Orthodontic force (30 cN) was applied on the maxillary first molar by an orthodontic appliance. Group E received 0.1 IU/kg/day of GH and Group C received 0.5 mL/kg/day of saline. The samples were processed and evaluated under optical microscopy and polarized light microscopy. The Kruskal Wallis test was applied to compare the intergroup variables at 5% significance level. Group E presented a larger number of osteoclasts on the 3rd and 7th days and Howship lacunae on the 3 rd day, a smaller number of blood vessels and greater amount of mature collagen on the 3 rd and 7 th days than Group C (p<0.05). It was concluded that GH accelerated and intensified bone resorption and produced delay in immature collagen formation during experimental tooth movement.

Aims The aim of this study was to compare individuals with and without schizophrenia through the characteristics of the palate, such as width, length, depth, palate shape, and upper dental arch shape. Methods and results The sample was divided into one case group (n = 45) and two control groups (n = 90; 45 individuals each group). Groups were paired by variables: sex, age, and malocclusion type. All analyses were performed on upper dental arch plaster models. All individuals were male and the mean age was 28.56 (SD: 7.82) years. The frequency of the malocclusion type observed was 54.1% (Class I), 22.2% (Class II), and 23.7% (Class III). Statistically significant difference was observed between the case and control groups for the variables palate shape (P = .004) and upper dental arch shape (P = .003). The case group had a higher frequency of the deep or grooved palate shape (57.8%) and parabolic dental arch shape (48.9%). There was no statistically significant difference for the palate width, length, and depth (P > .05). Conclusions There was an evidence that the deep or grooved palate shape and parabolic dental arch shape are morphological characteristics of the palate in men with schizophrenia.