Repositório RCAAP

Noncarious cervical lesions (NCL) are considered of multifactorial origin, associated, normally, to inadequate brushing. This study evaluated, in vitro, the simulated brushing influence on NCL formation. Fifteen human premolar had been submitted to brushing in the region of the cementoenamel junction using brushes with hard, medium and soft bristles, associated to toothpaste of medium abrasivity, under load of 200 g, speed of 356 rpm, during 100 min. The surface topography of the region was analyzed before and after the brushing, by means of a laser interferometer, under values of cut-off of 0.25. The initial results of roughness for dentine were: (D1) 1.25 ± 0.45, (D2) 1.12 ± 0.44, (D3) 1,05 ± 0,41 and for enamel: (E1) 1.18 ± 0.35, (E2) 1.32 ± 0.25, (E3) 1.50 ± 0.38; and after brushing the values for dentine were: (D1) 2.32 ± 1.99, (D2) 3.30 ± 0.96, and for enamel: (E1) 1.37 ± 0.31, (E2) 2.15 ± 0.90, (E3) 1.22 ± 0.47. By means of the statistical analysis of the results using Student t test and Tukey (P<.05) it can be concluded that soft, medium and hard brushes are not capable to wear enamel, while the dentine showed alteration in the superficial roughness by the action of the brushes with medium and hard bristles.

The aim of this study was to evaluate the influence of resin coat prior temporary cementing on bonding strength of fiber post to root dentine. Seventy-eight bovine tooth were sectioned and roots 15 mm in length were treated endodontically and prepared to receive the post. Sixty roots were used for mechanical testing of micro push-out, being that in a group the Clearfil SE Bond was applied before the temporary cementation to prepare the dentin, while while in the other group the Clearfil SE Bond before temporary cementation was not applied. Three types of temporary cement for fixation of temporary restorations were, are: calcium hydroxide cement-based, zinc oxide and eugenol cement-based and zinc oxide without eugenol cement-based. After 07 days, the temporary restorations were removed and the root canals were cleaned. The post were treated with 35% hydrogen peroxide and silanized. The post were cemented with self-adhesive cement Rely X U200. The seating of the post was five minutes and the excess was removed after the first 60 seconds. After the outer covering of the roots with the molding material, the samples will be photoactivated for 40 seconds on each surface. The roots were stored for 24 hours and then sectioned into slices for mechanical test micro push-out and analysis of the fracture pattern. Eighteen samples were used for evaluation through confocal laser scanning microscopic to analyze penetration and distribution of the resin cement and adhesive system. Data were analyzed by two-way ANOVA and Tukey test. The results showed that there was no statistically significant interaction between the use of a sealing agent and temporary cement (P = 0.375), excluding root thirds. In conclusion, the use of a sealing agent prior to the temporary cement did not result in higher bond strength of fiber post to the root dentin.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The aim of this study to evaluate the influence of different implant numbers, connection types and loading conditions on the biomechanical behavior of mandibular full-arch implant-supported rehabilitation in delay loaded protocol. Computer tomography based finite element models comprising a totally edentulous mandible and Ø 3.8 x 13-mm implants, abutments, abutment screws, bar retaining screw and bar were constructed. Different implant configurations (3, 4 and 5 implants) and loading conditions (symmetrical, unilateral and posterior with diverse loading magnitudes) were simulated for both external hex (EH) and Morse-taper connections (MT). Were evaluated peak equivalent strain (EQV strain) in the bone and the peak von Mises stress (EQV Stress) in abutment screw and bar retaining screw. Considering the same loading design, a significantly higher bone strain levels were observed for EH, comparing to MT connection. Implant number do not have a significant influence on strain magnitudes in bone, for neither the connection types. Regarding the EQV Stress in abutment screw, MT connection type presented significantly lower stress values, comparing to EH connection. The EQV stress in implant system (i.e. abutment screw and bar retaining screw) has an inverse relationship with the implant number. Morse-taper connection type significantly decreases the strain levels in periimplant bone and the EQV stress in abutment screw, however, showed higher EQV stresses in the retaining screws of the bar. A smaller number of implants in an inferior full-arch rehabilitation rather increase the stress in abutment and bar retaining screws. Balanced adjustments of the loading improve the biomechanics of an mandibular full-arch rehabilitation.

This study evaluated the influence of the torque given to the screws of the abutments on replicas of implants in working cast previously the laser welding procedures. From a master model with 4 implants with external hexagon was made a working cast. For the confection of metallic framework, abutments and pre-fabricated cylindrical bars of titanium had been used, which had been joined by means of laser welding to compose three groups: GS/T - group without torque, GT10 - group torque of 10 Ncm and GT20 - group torque of 20 Ncm. Before the weldings, the torque applied in the screws of group GS/T was only manual, without the use of torquemeter, and in groups GT10 and GT20 the abutment screws had received torque of 10 and 20 Ncm, respectively. After the weldings the abutment/implant interfaces in the vertical axle (y) had been evaluated in comparing optical microscope under magnification of 40 times. The readings had been made by means of two different methodologies. First the test of the only screw was used (TPU), in which evaluated the interfaces of screwed and not screwed abutments, considering only the extremities abutments of the frameworks. Later the interfaces of all abutments had been evaluated when these were screwed with torque of 20 Ncm. The data had been submitted to statistical analyses (P<.05). In the TPU, the intergroups analysis (Kruskal Wallis) did not show statistically significant difference for no condition of tightening, screwed and not screwed abutments, in other words, the torques of 10 Ncm and 20 Ncm pre-welding in groups GT10 and GT20 did not guarantee minors distortions of frameworks; the intragroups analysis (Wilcoxon) showed that for all the groups the interfaces of not screwed abutments had been statistically higher that the interfaces of the screwed abutments, in other words, had evidenced distortions in all frameworks after the weldings. The analysis of variance test (ANOVA) was applied for the comparisons of the interfaces when all abutments were screwed and did not have statistically significant difference between the groups (P=.686). The pre-welding torque in the abutments screws did not influence in the quality of adaptation of prosthetic frameworks over implants.

The osseointegration success depends on the integrity of the interface between abutment and peri-implant soft tissues. In this region, there is a sealing, which separates the internal and external environment. In order to have this stability it is necessary the realization of soft tissues normal function in an environment without bacteria and contamination inflammatory. Since the titanium abutments are the most user prosthetic resolutions and their sough surfaces accumulate plaque, which may lead to improve mucositis and peri-implantitis. This subject will characterize the superficial roughness of abutments being related to the accumulation of bacterial plaque. Eight patients rehabilitated with overdenture in the lower jaw, using two implants, had received two types of abutments with different surfaces (conventional and polishing) were observed. The average roughness initial and final of abutments had been evaluated through an interferometer the laser, brand UBM, model MICROFOCUS EXPERT IV and the presence of microorganism by means of aerobic and anaerobic bacterial cultures. The initial and final average roughness had remained equal in the conventional group (0,26µm), while that in the polishing components it has increased (0,11µm-0,14µm). A bigger amount of bacterial colonies had been observed in the group of the conventional components if compared with the group of the polishing components. Considering our results, we can conclude that the increase of the roughness contributes directly towards a bigger retention of plaque on the prosthetic components.

This study had the aim to identify the presence and the severity of noncarious cervical lesions (NCLs) and correlate them to the occurrence of premature dental contacts and to the risk factors involved in this development. There had been evaluated 66 patients of both genders, with age between 15 and 70 years, involving 1,863 teeth, which had been examined in accordance with criteria for identification of NCLs, wear facets and occlusals prematurities. The individuals had answered to the questionnaire related to the age, gender, gastrointestinal problems, medication use, dentin hypersensitiveness, diet and parafunctional habits. The evaluation of wear facets was achieved by means of visual inspection of the occlusal and incisal faces of teeth. In the identification of cervical lesions, the vestibular and lingual or palatine faces of teeth had been examined with periodontal probing located parallel to the long axis of the tooth. The teeth with NCLs had been evaluated as regards the severity, using the tooth wear index (TWI), and later examined with relation to the occlusion in centric relation (CR), maximal habitual intercuspation (MHI) and in the excursion movements. Two thirds of the individuals had presented the total of 273 cervical lesions. As regards to the distribution of lesions for group of teeth, the premolars had presented greater frequency, followed for molars and the incisors and canines with lesser frequency. The same trend was observed for wear facets. It had positive correlation between the presence of NCLs and the occlusals prematurities. For the data gotten with questionnaire, the Chi-Square test (&#945;=.05) demonstrated difference between the individuals with and without lesion for age, parafunctional habit and dentin hypersensitiveness. The most frequent TWI was which lesions had less than 1 mm. When analyzing the risk factors involved in noncarious cervical lesions, suggest the parafunctionals habits and occlusals prematurities as the etiology agents with greater potential to develop them.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Light and intermittent stimulus given by functional orthopedic appliances induce changes on the mandibular dynamics and consequently on its morphology. Discrepancies on the cranium-facial development are predisposing factors. Deep overbite is a malocclusion characterized by an excessive overbite among the anterior teeth. The aim of the present research was to quantify the angular and linear variations of individuals that presented deep overbite and were treated by Planas equilibrator (equiplan). 30 deep bite subjects up to 4 mm were selected in this research whose teleradiographies were taken after and before treatment. This values obtained were analyzed by student t test, ANOVA, Pearson s Correlations Coefficient and Determination Coefficient. All linear measurements increased, lower incisors tip and y growth axis too. No lower and upper incisors intrusion occurs. There were no differences among the cranial basis, the maxilar e mandibular planes, mandibular angle and upper incisors tip. The equiplan was efficient in deep bites treatments, inducing lower molar dento-alveolar growth, not intruding incisors or increasing facial planes divergences.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

The aim of this study was to test the hypothesis of that the type of gypsum and the thickness of the impression material influence in the dimensional alteration of prosthetic models. Master-Model of mandibular arch was confectioned, using two extracted human teeth: an inferior first molar, first premolar and absence of inferior second premolar, completed with acrylic resin teeth. The human teeth had received prepares for metal-ceramic full crown, six reference points had been established in each tooth, resulting in seven measurements: mesiodistal, buccopalatine and occlusal-cervico for both, and teeth interpillars distance. The prepared teeth had been molded by the shell technique in acrylic resin with relief in 2 thicknesses: 0,8mm and 1,5mm, using regular polysulfide (n= 30). The moulds had been poured with three types of special plaster: natural type IV (Vel-mix), artificial (Tuff-Rock) and type V (Exadur). Three examiners measured the master-die and the samples in microscope of measurement with precision of 1mm. The data had been analyzed statistically by means of ANOVA and test of Tukey (a=0,05), demonstrating that it did not have difference statistics in function of the thickness of the impression material. However, significant variation in the distance interpillars was verified on the types of gypsum and between these and the master-die, when dental stone type IV demonstrated more steady behavior. The gypsums (Exadur, Vel-mix e Tuff-rock) showed vertical behavior dimensionality stable in 61% of the measures (horizontal and vertical) and significances statistics differences in 39%, representing expansion, 17% to Exadur, 14% to Vel-mix and 11% to Tuff-rock.

Hyperbaric oxygen therapy (HBO) aims to minimize the risks of osteoradionecrosis (ORN) and to obtain success in surgical procedures involving manipulation of previously irradiated bone. However, HBO application protocols are not well-defined yet, and studies determining the ideal number of sessions have not been carried out to date. This work aimed to investigate the effect of HBO on tissue healing, correlating it to particular numbers of sessions. A total of 40 clinically healthy male Wistar rats, weighing between 250 and 350 g had their left legs irradiated with a single dose of 30 Gy. After 30 days, they were submitted to surgery to create a bone defect, immediately following HBO, using the variables of 0, 10, 20, 30 and 40 sessions, over 90 minutes per day, under 2.5 ATA. The animals were sacrificed and their tibiae submitted to a three point bio-mechanic test assay to calculate maximum strength (N), work to failure (mJ) and stiffness (N / mm). In addition, micro-CT was performed to analyze bone defects in the femur regarding: (1) bone volume percentage (BV / TV); (2) connectivity density (Conn. D); (3) Trabecular separation (Tb. Sp ); (4) Trabecular thickness (Tb. Th); (5) Trabeculae number (Tb.N). The three point test showed differences between the groups (I x NI) for 0 (p = 0.006), 10 (p = 0.049), 20 (p = 0.027), and 40 sessions (p = 0.047). Significant differences in trabecular separation were found among the various parameters evaluated in the micro-CT, when 0 and 20 sessions were compared (p<0.05). HBO favored bone tissue rigidity after radiotherapy and the number of HBO sessions performed did not influence the bone tissue healing process in rats.

The biomechanical of implants play an important hole in osseointegration. The finite element method provides a biomechanical study based on numerical evaluation from mathematical models. In this work, the von Mises stress from models with niobium implant was compared with titanium implant. A twodimensional model with screw type implant (4.1 x 10 mm) and cicatrizador (4.5 x 3 mm) in cortical and cancellous bone tissue was used. Force of 100 N was applied axially at the center surface of the cicatrizador. The materials on this analysis were assumed to be homogeneous, isotropic and linearly elastic. The analyzed stress was obtained from previously nodes selected on bone-implant contact, on implant, cortical and cancellous bone tissue inside. The results based on compared analysis between models with niobium implant and titanium showed a similar distribution of stress on implant, cortical and cancellous bone tissue inside, and bone-implant contact.

The present research had the objective to analyze qualitatively though histobacteriology, the remaining dentine of upper human premolars after removal of clinically decayed tissue, according to presence, location and distribution of microorganisms in dental tubules in different degrees of depth of carious lesion. It was selected representative histological blades of histological cut in series, obtained during the research of Biffi et al (1982), extracted from patients of both genera and age from 20 to 40 years old. The teeth should present proximal caries and/ or occlusal caries and the removal of decayed tissue would be done in vitro. The three faces (dental, mesial and occusal) were clinically classified according to the depth of the caries in degrees 0, 1, 2, 3, 4 or 5 and microscopically assessed. The blades were tinged using the technique of Hematoxylin and Eosine, Trichrome of Masson and histobacteriological of Gram, modified by Brown and Brenn. The interpretation of histological cuts was realized with the use of a trinocular and photomicroscope. In the descriptive analysis it was possible to check the bacterial penetration in a superficial way and/ or in a deep way in the dentinal tubules both in the pulpal floor or in the amelodentinal junction, as well as the presence of bacterial niches in the cavity preparation. The contaminated tubules showed morphologically inaltered, and in pulp exposure during the removal of deep caries it was verified the introduction of a contaminated dentinal fragment in the pulp tissue. In order to have a statistical analysis of the number of microorganisms, it was applied the Pearson s correlation coefficient, respectively among the different degrees of caries and localization in the amelodentinal junction and pulp floor. It was brought to a conclusion that, in 56,7% of the decayed faces the microorganisms were placed in dentine considered clinically healthy, in which they lodged in dentinal tubules morphologically inaltered; the localization and the distribution of microorganisms in the tubules were variable and independent of the depth of the caries.