Paulo Isaias Seraidarian

Urinary levels of catecholamines among individuals with and without sleep bruxism

IntroductionSleep bruxism (SB) is characterized by repetitive and coordinated mandible movements and non-functional teeth contacts during sleep time. Although the etiology of SB is controversial, the literature converges on its multifactorial origin. Occlusal factors, smoking, alcoholism, drug usage, stress, and anxiety have been described as SB trigger factors. Recent studies on this topic discussed the role of neurotransmitters on the development of SB.ObjectiveThus, the purpose of this study was to detect and quantify the urinary levels of catecholamines, specifically of adrenaline, noradrenaline and dopamine, in subjects with SB and in control individuals.Materials and methodsUrine from individuals with SB (n = 20) and without SB (n = 20) was subjected to liquid chromatography. The catecholamine data were compared by Mann–Whitney’s test (p ≤ 0.05).ResultsOur analysis showed higher levels of catecholamines in subjects with SB (adrenaline = 111.4 µg/24 h; noradrenaline = 261,5 µg/24 h; dopamine = 479.5 µg/24 h) than in control subjects (adrenaline = 35,0 µg/24 h; noradrenaline = 148,7 µg/24 h; dopamine = 201,7 µg/24 h). Statistical differences were found for the three catecholamines tested.ConclusionIt was concluded that individuals with SB have higher levels of urinary catecholamines.

Biomechanical analysis of the stresses generated by different disocclusion patterns in an implant-supported mandibular complete denture

Objectives: This study evaluated by three-dimensional finite element analysis the tensions generated by different disocclusion patterns (canine guide and bilateral balanced occlusion) in an implant-supported mandibular complete denture. Material and Methods: A three-dimensional model of implant-supported mandibular complete denture was fabricated according to the Brånemark protocol. A 5-element 3.75 x 13-mm screw-shape dental implant system was modeled for this study. The implants were located in the intermental foramen region with 3-mm-high prosthetic components joined by a nickel-chromium framework with 12-mm bilateral cantilever covered by acrylic resin and 12 acrylic denture teeth. SolidWorks® software was used before and after processing the simulations. The mechanical properties of the components were inserted in the model and a 15 N load was established in fixed points, in each one of the simulations. Data were collected in the entire nickel-chromium framework. The results were displayed three-dimensionally as color graphic scales. Results: The canine guide generated greater tensions in the region of the first implant, while the bilateral balanced occlusion generated great tensions in the entire metallic framework. The maximum tension found in the simulation of the bilateral balanced occlusion was 3.22 fold higher than the one found in the simulation of the disocclusion in canine guide. Conclusion: The pattern of disocclusion in canine guide is the ideal for implant-supported mandibular complete denture.

Stress analysis on the free-end distal extension of an implant-supported mandibular complete denture

A comparative and qualitative analysis of the tensions generated in the cantilever region of an implant-supported mandibular complete denture was conducted using the three-dimensional finite element method. The mechanical properties of the components were input in the model and a load of 15 N was applied in pre-determined points. In the first simulation, the load was applied on the occlusal surface of the first premolar. In the second simulation, it was applied on the first and second premolars. In the third simulation, it was applied on the first and second premolars and on the first molar. The different occlusion patterns produced similar tension distributions in the cantilever region, which followed a similar pattern in the three simulations. In all of the cases, the highest levels of tension were located in the region of the first implant. However, as the loads were dislocated distally, the tensions increased considerably. The more extensive the cantilever, the more compromised will be the infrastructure, the prosthetic components and the implants. Regardless of the length of the cantilever, the highest tensions will always be located in the region of the implant next to the load application point.

Avaliação de monômero residual em resinas acrílicas de uso ortodôntico e protético: análise por espectroscopia

AIM: Two comercial brands of auto polymerizing acrylic resins (one for orthodontics use, Orto Cril®, and the other for prosthetics use, Jet®) were analyzed concerning the amount of methyl methacrilate (MMA) monomer dissolved in solution, processed under and not under pressure, in different intervals (0.083; 0.25; 1; 1.25; 2.17; 5; 9; 14 and 21 days). METHODS: The ultra-violet absorption spectroscopy was used in the analysis of aqueous solutions of MMA, with known concentrations, in order to determine the calibration curve. Aqueous solutions containing samples made with the acrylic resins described above were submitted to ultra-violet absorption spectroscopy analysis. RESULTS AND CONCLUSIONS: The results were compared to the calibration curve data, in order to establish the MMA concentration. These results led to the conclusion that the residual MMA level dissolved in the solution was higher in the first twenty-four hours, tending to stability from this period on. Auto polymerizing acrylic resins processed under pressure showed higher levels of MMA, even though it was not noticed an interaction effect between the resins brand and the presence of pressure in the level of MMA concentration measured throughout the intervals. In spite of that, the three variables (time, resins and pressure) were of noticeable importance.

Determination of vertical dimension of occlusion in dentate patients by cephalometric analysis - pilot study

OBJECTIVES The concept of vertical dimension of occlusion (VDO) refers to a measure in the vertical plane that establishes the relation between the maxilla and the mandible when the posterior teeth, both from the maxillary and from the mandibular arches, are occluded, regardless of whether they are natural or prosthetic, healthy or restored. This measure is subject to change, and when this occurs, it can compromise both the function and the facial aesthetics. This study proposed to develop a methodology based on cephalometric analysis by studying the 31 lateral teleradiographs of adult, dentate individuals to determine the VDO, based on bone structures that are not dependent on the presence or absence of posterior teeth. The final goal was to make this application accessible to individuals who have undergone alterations of the lower portion of the face. MATERIALS AND METHODS The cephalometric analysis of this study, called Seraidarian-Tavano, was verified through facial angles (upper and middle angles) that, when correlated, determine the lower position of the face. RESULTS The analysis of results showed that no statistically significant difference between the angles studied could be observed (superior angle 50.29 ± 3.35 e median angle 49.95 ± 3.37). In the same manner, no variation in the results regarding gender in the measure of these angles could be observed. CONCLUSION This cephalometric analysis can be applied to determine the VDO, regardless of the presence or absence of posterior teeth.

Tooth displacement in shortened dental arches: A three-dimensional finite element study

STATEMENT OF PROBLEM Some patients may opt for a prosthetic rehabilitation without replacing all missing teeth, finishing treatment with a reduced dental arch. This choice may be due to biologic reasons or financial restrictions. It is unclear if a reduced dental arch functions as well as a complete dental arch. PURPOSE The purpose of this study was to analyze whether shortened dental arches could result in tooth displacement. MATERIAL AND METHODS Four different 3-dimensional maxillary and mandibular arches with different levels of arch length reduction were created. In all models, anatomic structures that represent the temporomandibular joint, cortical and cancellous bone, enamel, dentin, and periodontal ligament were modeled. Mechanical properties were attributed to each anatomic component, and a total occlusal load of 100 N on masseter, temporal, and medial pterygoid muscles was simulated for each model. The MSC. Patran software was used for the preprocessing and postprocessing of the biomechanical analysis of the models. One complete dental arch was used as the control. RESULTS The simulations showed that shortened dental arches presented greater tooth displacements than those found in a complete dental arch. The changes in mandibular tooth position were greater than those observed in the maxillary arches. In finite element models 1 and 2, the largest maxillary displacements were found for posterior teeth. CONCLUSIONS Decreasing numbers of occlusal units resulted in increasing amounts of displacements of the remaining teeth, which may compromise dental stability in patients with shortened dental arches.

Avaliação dos níveis de pressão sonora emitidos pelo aparelho de ressonância magnética

Purpose: to measure the sound pressure level emitted by the magnetic resonance imaging in operation and check the auditory sensations described by individuals submitted to this examination after it has been carried out. Methods: the measurement of the deep noise was conducted during image formation in this examination, by means of sound pressure level meter (decibel meter) and the application of a questionnaire for the purpose of checking the hearing sensations presented by those individuals after the exam has been carried out. This procedure was applied to sixty individuals submitted to a magnetic resonance imaging of the skull. Results: it was found that the average of sound pressure level presented while the examination was carried out was lower than the level of intensity considered being a risk for auditory damages. However sensations like tinnitus, anxiety, auricular plenitude and relief after the end of the examination were mentioned by the individuals after it had been carried out. Conclusion: the use of hearing protectors is relevant as a preventive measure for controlling the level of noise that affects the individuals cochlea, thus minimizing the physical and psycho-social effects resulting from noise exposure.

Successful and stable orthodontic camouflage of a mandibular asymmetry with sliding jigs

The purpose of this paper is to present and discuss a simple and low-cost clinical approach to correct an asymmetric skeletal Class III combined to an extensive dental open bite that significantly compromised the occlusal function and smile aesthetics of an adult male patient. The patient did not accept the idealistic surgical-orthodontic treatment option, neither the use of temporary anchorage devices to facilitate the camouflage of the asymmetrical skeletal Class III/open bite. Therefore, a very simple and inexpensive biomechanical approach using sliding jigs in the mandibular arch was implemented as the compensatory treatment of the malocclusion. Although minor enhancements in facial aesthetics were obtained, the occlusal function and dental aesthetics were significantly improved. Furthermore, the patient was very satisfied with his new smile appearance. Some advantages of this treatment option included the small invasiveness and the remarkably low financial costs involved. Moreover, the final results fulfilled all realistic treatment objectives and the patients expectations. Results remained stable 5 years post-treatment demonstrating that excellent results can be obtained when simple and low cost, but well-controlled mechanics are conducted.

Association Between In-Office And At-Home Tooth Bleaching: A Single Blind Randomized Clinical Trial

This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

Uso da radiografia transcraniana para detectar alterações morfológicas no côndilo mandibular

Purpose: to evaluate the accuracy of conventional transcranial radiographs (TRANS) to identify morphological changes in mandibular condyles. Methods: the sample consisted of 36 mandibular condyles, obtained from 18, randomly selected, dried human skulls, without the identification of age, gender, or ethnicity. Three experts in dental radiology examined the TRANS to identify possible changes in the condyles. The fourth examiner performed the macroscopic examination, which was considered the gold standard of the study. The condyles in both TRANS images and macroscopic examinations were classified as mandibular condyles with change (1) or no change (0). Statistical analyses were performed using the X 2 and the receiver operating characteristic (ROC) curve. Kappa intra- and interobserver tests were performed for examiners 1 to 3. Results: the X2 test showed a statistically significant association between changes in the condyle in the TRANS images and the presence of macroscopic changes in the condyle (p ( 0.05). The area under the curve was 0.83, with 96% sensitivity and 70% specificity. The weighted kappa value for intraobserver agreement was 0.78, while the interobserver agreement was 0.71. Conclusion: the use of TRANS proved to be an effective method to detect morphological changes in the mandibular condyle.