Morphological Study of Myoneural Interaction between the Levator Labii Superioris Muscle and its Motor Nerve in Rats

The progress of science in search of new techniques of the nerve regeneration and the functional repair in reinnervated muscle has been the target of many researchers around the world. Consequently, nerves and muscles in different body segments asked for more enlightenment of their morphology, their interrelation with other anatomic structures and their peculiarities. One of the most significant areas that need deeper studies is the region of the head and neck, since they are often affected by important pathologies. In order to offer the researcher`s community a morphological myoneural interaction model, this study elected the levator labii superioris muscle and its motor nerve, the buccal branch of the facial nerve (VII pair) not only for its special characteristics, but also its value on the facial expression. The rat was chosen for this investigation for being easy to obtain, to keep, to manipulate and to compare this experiment with many others studies previously published. The techniques used were Mesoscopic (dissection), histoenzymologic and morphometric ones. In the results the muscle proved to have a predominance of fast twich fibers (FG and FOG) and superficial location, with a proximal bone and a distal cutaneous insertion. Its motor nerve, the buccal branch of the facial nerve (VII pair), breaks through the muscle belly into its deep face, and comprised a heterogeneous group of myelinic nerve fibers disposed in a regular form in all fascicle. Near the motor point, the nerve showed to be composed of two fascicles with different sizes. Due to the small nerve dimensions, the nerve fibers have a smaller diameter if compared to the motor nerve of pectineus muscle of the cat. Further studies with neural tracers have already had a start in order to provide more information about the distribution and the architecture of these fibers.

Bone repair and augmentation using block of sintered bovine-derived anorganic bone graft in cranial bone defect model

To histomorphometrically investigate the repair of critical size defects (CSDs) and bone augmentation in cranial walls using block of sintered bovine-derived anorganic bone (sBDAB) graft. Forty guinea-pigs were divided into test (n=20) and CSD control (n=20) groups. In each animal, a full-thickness bone defect with 9.5 mm diameter was made in the frontal bone. The defects were filled with an sBDAB block soaked in blood in the test group and with blood clot in the CSD control group. The skulls were collected at 0 h (n=2) and 30, 90 and 180 days (n=6/group and period) postoperatively. The volume density and total volume of newly formed bone, sBDAB, blood vessels and connective tissue, vertical thickness of removed bone plug, sBDAB block and graft area were evaluated. The vertical thickness of the adapted sBDAB block was 3.8 times higher than that of the removed bone plug and did not show significant difference between periods, filling in average 29.8% of the total graft region. The sBDAB block exhibited complete osseointegration with the borders of the defect at 90 days. At 90 and 180 days, the vertical thickness of the graft was 279% in the average, and the total volume of bone augmentation was, respectively, 78.8% and 148.5% higher compared with the removed bone plug. The defects of the CDS control group showed limited osteogenesis and filling by connective tissue plus tegument. The sBDAB block can be used to promote repair of CSDs and bone augmentation in the craniomaxillofacial region, due to its good osteoconductive and slow resorptive properties. To cite this article:Cestari TM, Granjeiro JM, de Assis GF, Garlet GP, Taga R. Bone repair and augmentation using block of sintered bovine-derived anorganic bone graft in cranial bone defect model.Clin. Oral Impl. Res. 20, 2009; 340-350.doi: 10.1111/j.1600-0501.2008.01659.x.

Influence of nicotine on healing process of autogenous bone block grafts in the mandible: A histomorphometric study in rats

Purpose: The aim of this study was to perform qualitative and quantitative analyses of the effect of nicotine on autogenous bone block grafts and to describe events in the initial healing phase and the differences in the repair processes between animals exposed to nicotine and controls. Materials and Methods: Forty-eight female Wistar rats were randomly divided into 2 groups, the nicotine group and the saline group. All animals received either nicotine (3 mg/kg) or saline 4 weeks before the surgical procedure and continued to receive nicotine from surgery to sacrifice at 7, 14, or 28 days. The autogenous bone block graft was harvested from the calvaria and stabilized on the external cortical area near the angle of the mandible. Results: The histologic analyses of the nicotine group depicted a delay in osteogenic activity at the bed-graft interface, as well as impairment of the organization of the granulation tissue that developed instead of blood clot. Nicotine-group specimens exhibited less bone neoformation, and the newly formed bone was poorly cellularized and vascularized. The histometric analysis revealed significantly less bone formation in the nicotine group at both 14 days (23.75% +/- 6.18% versus 51.31% +/- 8.31%) and 28 days (42.44% +/- 8.70% versus 73.00% +/- 4.99%). Conclusion: Nicotine did jeopardize the early healing process of autogenous bone block grafts in rats but did not prevent it.

Recurrent peripheral odontogenic keratocyst: a case report

A case of peripheral odontogenic keratocyst arising in it 57-year-old white female patient involving the posterior mandibular gingiva that recurred after 12 months of fellow-up is presented. This reported case reinforces that patients presenting peripheral odontogenic keratocyst should be carefully followed up after conservative surgical treatment.

Serotonergic neurons in the nucleus raphe obscurus contribute to interaction between central and peripheral ventilatory responses to hypercapnia

Serotonergic (5-HT) neurons in the nucleus raphe obscurus (ROb) are involved in the respiratory control network. However, it is not known whether ROb 5-HT neurons play a role in the functional interdependence between central and peripheral chemoreceptors. Therefore, we investigated the role of ROb 5-HT neurons in the ventilatory responses to CO(2) and their putative involvement in the central-peripheral CO(2) chemoreceptor interaction in unanaesthetised rats. We used a chemical lesion specific for 5-HT neurons (anti-SERT-SAP) of the ROb in animals with the carotid body (CB) intact or removed (CBR). Pulmonary ventilation (V (E)), body temperature and the arterial blood gases were measured before, during and after a hypercapnic challenge (7% CO(2)). The lesion of ROb 5-HT neurons alone (CB intact) or the lesion of 5-HT neurons of ROb+CBR did not affect baseline V (E) during normocapnic condition. Killing ROb 5-HT neurons (CB intact) significantly decreased the ventilatory response to hypercapnia (p < 0.05). The reduction in CO(2) sensitivity was approximately 15%. When ROb 5-HT neurons lesion was combined with CBR (anti-SERT-SAP+CBR), the V (E) response to hypercapnia was further decreased (-31.2%) compared to the control group. The attenuation of CO(2) sensitivity was approximately 30%, and it was more pronounced than the sum of the individual effects of central (ROb lesion; -12.3%) or peripheral (CBR; -5.5%) treatments. Our data indicate that ROb 5-HT neurons play an important role in the CO(2) drive to breathing and may act as an important element in the central-peripheral chemoreception interaction to CO(2) responsiveness.