Electromyographic Activity of Masseter and Temporal Muscles with Different Facial Types

Objectives: To compare the electromyographic (EMG) activity of the masseter and anterior portion of temporal muscles in different vertical facial types. Materials and Methods: Clinical examination, cephalometric analysis, and electromyographic examination were performed in 44 volunteers ranging from 18 to 35 years old. The volunteers were classified on the basis of their vertical facial characteristics into three groups-brachyfacial, mesofacial, and dolicofacial-by the grouping analysis. The EMG records were obtained with three repetitions during mandibular rest, maximum voluntary contraction in intercuspidation, and simultaneous bilateral isotonic contraction. The Kolmogorov-Smimov and Levene tests were applied to verify the normality and homogeneity of variance. Analysis of variance and the Kruskal-Wallis test identified statistical differences among groups that did not present normality and homogeneity of distribution, respectively. Significance for all statistical tests was set at P <.05. Results: At rest, only the right temporal and masseter muscles presented statistically significant differences among the groups. The differences were observed between groups 1 and 2 (P =.02) and 1 and 3 (P =.038) for the right temporal muscle, and between groups 1 and 2 (P =.029) for the right masseter muscle. Generally, group 1 presented the lowest EMG values for the four muscles evaluated during rest. For isotonic evaluation, none of the groups of muscles presented statistically significant differences. Conclusion: Different vertical facial types do not determine distinct patterns of EMG activity for the masseter and anterior portion of temporal muscles during rest and bilateral mastication. (Angle Orthod. 2009;79:515-520.)79351552

Anthropometric Comparison between Mandibles from Uruguayan and Brazilian Populations

The human mandibles belonging to Uruguayan population present some anatomic differences with those belonging to Brazilian population. This appears to be determined by racial and ethnic characteristics of each country. This study examined the morphological characteristics of 100 Uruguayan mandibles and compared them with similar number of Brazilian bones, using thirteen measurements stipulated by Humphrey et al. (1999). The significant variations in mean values were calculated by Mann-Whitney test (alpha=5%). Expressive discrepancies were observed between the two populations regarding some of analyzed dimensions. The Uruguayan mandibles showed higher values in almost all measurements when compared to the Brazilian ones, except for the mandibular symphysis height, which was lightly higher in Brazilian mandibles. Differences were observed in notch and ramus height, mandibular length, mandibular width, symphysis height and bicoronoid width. Several factors could be responsible for these morphological discrepancies, including functional and biomechanical adaptations of stomatognathic system, stimulated by different consistency of the diet or miscegenation.30237938

The buccinator during mastication: A functional and anatomical evaluation in minipigs

Objective: The buccinator muscle forms the lateral wall of the oral cavity. It is presumed to aid mastication by maintaining bolus position. Such a function would involve thickening the cheek, possibly compressing the alveolar bone and contributing to malocclusions. However, neither buccinator deformation nor its effect on pressure has been demonstrated. Our objective was to evaluate buccinator EMG during feeding, its changes in length and thickness, and the pressure exerted on its alveolar attachment, using miniature pigs as an animal model. Methods: EMG of the buccinator and other oral muscles was recorded with fine-wire electrodes. Anteroposterior length and mediolateral thickness of the buccinator were evaluated with implanted sonomicrometry crystals, and pressure was measured by flat transducers placed beneath the mandibular origin of the buccinator. Recordings were made during feeding and muscle stimulation. Tissues were collected postmortem for histology. Results: During mastication, buccinator EMG showed regular peaks that preceded those of the jaw closers. Pattern differences clearly distinguished working and balancing sides. The buccinator shortened and thickened when it contracted. Positive pressures were observed at the mandibular attachment of the buccinator, increasing when the muscle was active. Histological evaluation showed a complex interweaving of fibres closely associated with salivary tissue. Conclusions: Buccinator contraction does thicken the cheek, and during mastication this activity takes place just as the closing stroke begins. In addition to controlling the bolus, there may be an effect on salivation. Despite the fact that the muscle pulls on its attachment, the local mechanical environment at the alveolar bone is one of positive pressure. (C) 2010 Elsevier Ltd. All rights reserved.559627638NIDCR [DE08513]National Council for Scientific and Technological Development-BrazilNIDCR [DE08513

Biological assessment of porous-implant hydroxyapatite combined with periosteal grafting in maxillary defects

Purpose: To investigate the use of porous hydroxyapatite (HA) combined with periosteal graft to repair an induced maxillary bone defect. Materials and Methods: A defect was produced in the premaxillary bone of rats. Four groups were used: 1) those treated with the mucoperiosteal graft from the premaxilla; 2) those treated with HA combined with mucoperiosteal graft from the premaxilla; 3) those treated with HA combined with periosteal graft from the femur; and 4) those treated with periosteal graft from the femur. Results: The radiographic aspects from all groups showed no signs of bone formation after 2 weeks. After 16 weeks, there was evidence of points of radiolucency inside the HA implants. Cell proliferation occurred from the periosteum covering the defect. Bone tissue grew from the defect margin to inside the defect in all cases. Mature bone was seen around the HA implants after 8 and 16 weeks. Conclusion: The periosteal graft provides satisfactory support to the HA implant, allowing the growth of new bone. (C) 2007 American Association of Oral and Maxillofacial Surgeons.65584785

Phototherapy and resistance training prevent sarcopenia in ovariectomized rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The aim of this study was to histologically and biochemically analyze the effects of light-emitting diode therapy (LEDT) associated with resistance training to prevent sarcopenia in ovariectomized rats. Forty female Wistar rats (12 months old, 295-330 g) were bilaterally ovariectomized and divided into four groups (n = 10 per group): control-sedentary (C), resistance training (T), LEDT-sedentary (L), and LEDT plus resistance training (LT). Trained rats performed a 12-week water-jumping program (3 days per week) carrying a load equivalent to 50-80 % of their body mass strapped to their back. Depending on the group protocol, the LED device (850 nm, 100 mW, 120 J/cm(2), spot size 0.5 cm(2)) was used either as the only method or after the resistance training had been performed. The device was used in the single point contact mode (for 10 min). The irradiated region was the center of the greater trochanter of the right femur and the middle third of the rectus femoris muscle was subsequently analyzed histomorphometrically. Significant increases (p < 0.05) were noted for the muscle volume of the T (68.1 +/- 19.7 %), the L (74.1 +/- 5.1 %), and the LT (68.2 +/- 11.5 %) groups compared to the C group (60.4 +/- 5.5 %). There were also significant increases in the concentrations of IGF-1, IL-1, and TNF-alpha in the muscles of the treated groups (p < 0.05). Animals in the LT group showed a significant increase in IL-6 compared to T, L, and C groups (p < 0.05). These findings suggest that resistance training and LEDT can prevent sarcopenia in ovariectomized rats.28614671474Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Cross-sectional study of correlation between mandibular incisor crowding and third molars in young Brazilians

Objectives: The aim of this study was to evaluate transversally the clinical correlation between lower incisor crowding and mandible third molar. Study Design: Three hundred healthy volunteers (134 male and 166 female), aged 20.4 (+/- 2.4) years-old were submitted to a complete clinical examination and filled up a questionnaire about gender, age, total teeth number and presence or absence of superior and inferior third molar. After a recent panoramic radiography were evaluated. The multiple logistic regression showed that none of the studied factors influenced the mandibular incisor crowding. Results: The proportion of both molars present or both absent was higher than the other conditions (Chi-square, p.05) the mandibular incisor crowding. Despite the statistical significance, wear orthodontics appliances showed a little correlation (odds ratios < 1.0) in the mandibular incisor crowding. Conclusion: Presence of maxillary and/or mandibular third molars has no relation with the lower incisor crowding.183E505E50

Morphometric Study of Orbital Region for Craneofacial Implant Applications

The aim of this research was to study the morphometric relation present in periorbital region, used in the installation of craniofacial implants. A descriptive study was carried out using 40 skulls between 20 and 60 years of age from the LaboratOrio de Anatomia do Departamento de Morfologia da Facultade de Odontologia de Piracicaba da Universidade Estadual de Campinas. Volumetric tomography with cone beam technique was used along with virtual reconstruction, with the point of analysis being selected based on the clinical and anatomical scientific literature. Orbital division was realized with minimal distance from the frontal and maxillary sinus. During measurement it was observed that the superior orbital rim presented a sagittal bone distance of 8.14mm +/- 1.91 mm; inferior orbital rim of 7mm +/- 1.71 mm, and the lateral orbital presented an average of 7.91 mm +/- 1.15 mm, considering that craniofacial implants present up to 6 mm in length, the installation of implants in this area is considered safe in terms of regional bone quantity requirements.291222

Craniofacial Morphometry for Craniofacial Implant

Craniofacial implants are being increasingly used to treat patients with sequelae of oncological resections, trauma, and congenital deficiencies, among other issues. The aim of this investigation was to establish the minimum and maximum bone dimensions present in the most used places for the insertion of craniofacial implants. A descriptive study was designed analyzing 40 human skulls using cone-beam computed tomography; in the volumetric reconstruction the points most often used in clinical investigations for the insertion of implants were selected, representing the orbital, perinasal, zygomatic bone and periauricular regions, measuring the distance between the cortical bones on the sagittal, axial and coronal planes; comparisons between gender and with other investigations with a similar aim were also made. In the supraorbital area, values of 7.92 +/- 1.82 mm were found and in the lateral area values of 7.54 +/- 0.98 mm, allowing the placement of implants 5 or 6 mm in length. In the area of the zygomatic bone, dimensions of 10.4 +/- 2.35 mm were obtained, allowing the placement of implants 8 mm in length. In the periauricular area values were obtained of 2.93 +/- 0.55 mm in the superior region and 3.1 +/- 0.7 mm in the inferior region, whereas in the perinasal area implants 4 mm in length can be placed. We concluded that the craniomaxillofacial bone structure presents acceptable widths for the installation of implants; the periauricular region presents lower dimensions, with the possibility of intracranial communication in areas above the external auditory meatus.3031166117

Morphometric study of maxillary sinus by computed tomography. Assessment of sinus floor bone reconstruction

Rehabilitation with dental implants in posterior maxilla is difficult because of the presence of maxillary sinus with anatomical variations. The aim of this research was to evaluate the sinus volume to install one or more implants without invading the sinus membrane. Forty (40) maxillary sinuses were evaluated in 22 skulls by computed tomography measuring in the axial, coronal and sagittal slice. The sinus were classified according to the remaining alveolar bone and a dental implant in the place of the upper first molar was virtually installed by implant view software. With this final volumetric measurement the surgical indications were established for inlay reconstruction from intra oral donor sites frequently evaluated in world literature. Group I (1mm to 4mm of alveolar ridge) showed a bone deficit of 1.98 cm(3), group II (4mm to 7mm) showed a deficit of 1.06 cm (3); group III (7mm to 10mm) showed a 0.67 cm(3) deficit. In view of these results we concluded that intra oral donor site can be used for the three study groups and in some cases in bilateral reconstruction.30259259