Ultrastructure of Motor Nerve Terminals in the Anterior Third of Wistar Rat Tongue

The nerve terminals of intrinsic muscular fibers of the tongue of adult wistar rats was studied by using silver impregnation techniques, transmission electron microscopy (TEM), and high resolution scanning electron microscopy (HRSEM) to observe the nerve fibers and their terminals. Silver impregnation was done according to Winkelman and Schmit, 1957. For TEM, small blocks were fixed in modified Karnovsky solution, postfixed in 1% buffered osmium tetroxide solution, and embedded in Spurr resin. For HRSEM, the parts were fixed in 2% osmium tetroxide solution with 1/15 M sodium phosphate buffer (pH 7.4) at 4 degrees C for 2 h, according to the technique described by Tanaka, 1989. Thick myelinated nerve bundles were histologically observed among the muscular fibers. The intrafusal nerve fiber presented a tortuous pathway with punctiform terminal axons in clusters contacting the surface of sarcolemma. Several myelinated nerve fibers involved by collagen fibers of the endoneurium were observed in HRSEM in three-dimensional aspects. The concentric lamellae of the myelin sheath and the axoplasm containing neurofilaments interspersed among the mitochondria were also noted. In TEM, myofibrils, mitochondria, rough endoplasmic reticulum, Golgi`s apparatus, and glycogen granules were observed in sarcoplasm. It is also noted that the sarcomeres constituted by myofilaments with their A, I, and H bands and the electron dense Z lines. In areas adjacent to muscular fibers, there were myelinated and unmyelinated nerve fibers involved by endoneurium and perineurium. In the region of the neuromuscular junction, the contact with the sarcolemma of the muscular cell occurs forming several terminal buttons and showing numerous evaginations of the cell membrane. In the terminal button, mitochondria and numerous synaptic vesicles were observed. Microsc. Res. Tech. 72:464-470, 2009. (C) 2009 Wiley-Liss. Inc.

Qualitative Analysis of the Removal of the Smear Layer in the Apical Third of Curved Roots: Conventional Irrigation versus Activation Systems

Introduction: The aim of this study was to evaluate the effectiveness of different irrigant agitation techniques on smear layer removal in curved root canals. Methods: Mesiobuccal canals of 62 extracted lower molars with a curvature of 33 degrees were used and instrumented up to Pro Taper F2. The samples were divided into 3 experimental groups according to the final irrigation: conventional irrigation, ultrasonic irrigation, and sonic irrigation by using the Endo Activator system. The control group was composed of 2 specimens without any final irrigation. In all of the experimental groups, 5 mL of 17% ethylenediaminetetraacetic acid was used for 1 minute, and 5 mL of 2.5% NaOCl was used for 30 seconds. The analysis of the apical region was performed via scanning electron microscopy by 3 examiners. The data were submitted to the Kruskal-Wallis and Dunn tests (P<.05). Results: The activation systems removed significantly more smear layer than did conventional irrigation. Conclusions: Sonic and ultrasonic irrigation resulted in better removal of the smear layer in the apical third of curved root canals than did conventional irrigation. (J Endod 2011;37:1268-1271)

Bone crestal height and bone density after third-molar extraction and grafting: a long-term follow-up study

The objective of this study was to evaluate the long-term influence of xenogenic grafts on bone crestal height and radiographic density following extraction of teeth. The right and left third lower molars of 22 patients were surgically extracted, and one randomly chosen socket was filled with a xenogenic graft (Gent-Tech). The contralateral molar was left to heal naturally, serving as a paired control. Digital intraoral radiographies were taken at surgery and 2, 6, and 24 months after, to evaluate bone density (BD) and alveolar bone crest to cementoenamel junction distance. The data obtained were subjected to two-way analysis of variance and Tukey`s test (alpha = 0.05). The significant decrease in cementoenamel junction distance observed for both groups was limited to the first 6 months. BD values increased significantly in the first 6 months, with no alterations observed up to 24 months for both groups. BD was higher for the experimental group at all time points (p < 0.05). Socket grafting with the xenogenic materials tested did not changed bone crestal height and bone radiographic density in the long term.

Impacted Lower Third Molar Fused with a Supernumerary Tooth - Diagnosis and Treatment Planning Using Cone-Beam Computed Tomography

Osny Ferreira-Junior, Luciana Dorigatti de Avila, Marcelo Bonifacio da Silva Sampieri, Eduardo Dias-Ribeiro, Weiliang Chen, Song Fan. Impacted Lower Third Molar Fused with a Supernumerary Tooth-Diagnosis and Treatment Planning Using Cone-Beam Computed Tomography. International Journal of Oral Science, 1(4): 224-228, 2009 This paper reported a case of fusion between an impacted third molar and a supernumerary tooth, in which a surgical intervention was carried out, with the objective of removing the dental elements. The panoramic radiography was complemented by the Donovan`s radiographic technique; but because of the proximity of the dental element to the mandibular ramus, it was not possible to have a final fusion diagnosis. Hence, the Cone-Beam Computed Tomography-which provides precise three-dimensional information-was used to determinate the fusion diagnosis and also to help in the surgical planning. In this case report we observed that the periapical, occlusal and panoramic were not able to show details which could only be examined through the cone-beam computed tomography.

Comparison of oral versus sublingual piroxicam during postoperative pain management after lower third molar extraction

In this study, 53 patients received piroxicam, administered orally or sublingually, after undergoing removal of symmetrically positioned lower third molars, during two separate appointments. This study used a randomized, blind, cross-over protocol. Objective and subjective parameters were recorded for comparison of postoperative results for 7 days after surgery. Patients treated with oral or sublingual piroxicam reported low postoperative pain scores. The patients who received piroxicam orally took a similar average amount of analgesic rescue medication compared with patients who received piroxicam sublingually (p > 0.05). Patients exhibited similar values for mouth opening measured just before surgery and immediately following suture removal 7 days later (p > 0.05), and showed no significant differences between routes of piroxicam administration for swelling control during the second or seventh postoperative days (p > 0.05). In summary, pain, trismus and swelling after lower third molar extraction, independent of surgical difficulty, could be controlled by piroxicam 20 mg administered orally or sublingually and no significant differences were observed between the route of delivery used in this study.

Evaluation of the buccal vestibule-palatal diffusion of 4% articaine hydrochloride in impacted maxillary third molar extractions

Aims: The aim of this study was to evaluate the vestibular-palatal diffusion of 4% articaine with epinephrine 1: 100,000 and 1: 200,000, in impacted maxillary third molar extractions, without palatal injection. Materials and Method: Two hundred teeth were selected from patients age 15 to 46. Patients were divided into 4 groups: 1A, were anesthetized with 4% articaine 1: 100,000 and the surgery was initiated 5 minutes following anesthesia. 1B, used 4% articaine 1: 100,000 but the surgery was started 10 minutes after anesthesia. 2A, used 4% articaine 1: 200,000 the surgery was started 5 minutes after. 2B, used 4% articaine 1: 200,000 but 10 minutes was allowed for anesthetic diffusion before the initiation of in groups (50 extractions each) only buccal vestibule anesthesia was initially administered (i.e. no palatal injections were used). Results: The rate of sufficient vestibule-palatal diffusion, as determined by the lack of necessity of supplemental palatal anesthesia, was: 1A(84%), 1B(98%), 2A(78%), 2B(82%). Chi-square (X2) and residual analyses showed that a higher vestibule-palatal diffusion was obtained using 4% articaine 1: 100,000 with a period of 10 minutes (p<0.05). Conclusions: Most of the extractions could be performed only with vestibule anesthesia. However, vasoconstrictor concentration and the time interval between administration of the anesthetic and initiation of surgery did influence buccal vestibule-palatal diffusion of 4% articaine in the extraction models used.

A comparison of the clinical anesthetic efficacy of 4% articaine and 0.5% bupivacaine (both with 1 : 200,000 epinephrine) for lower third molar removal

Objective: This study compared the clinical efficacy of 4% articaine (A200) and 0.5% bupivacaine (B200), both with 1: 200,000 epinephrine, for lower third molar removal. Study design: Fifty patients underwent removal of symmetrically positioned lower third molars, in 2 separate appointments, under local anesthesia either with A200 or B200, in a double-blind, randomized, and crossover manner. Time to onset, duration of postoperative analgesia, duration of anesthetic action on soft tissues, intraoperative bleeding, and hemodynamic parameters were evaluated. Results: A statistically significant difference between the time to onset of A200 (1.66 +/- 0.13 minutes) and B200 (2.51 +/- 0.21 minutes) was found (P < .05). There was no statistically significant difference in the duration of analgesia, whether the patient was subjected to osteotomy or not, regardless of the local anesthetic used (3 to 4 hours; P < .05). However, when patients received B200 they experienced a statistically significant longer period of anesthesia on the soft tissues as compared with when they had received A200 (around 5 hours and 4 hours, respectively, P < .05). The surgeon`s rating of intraoperative bleeding was considered very close to minimal for both anesthetics. In the surgeries with osteotomy, the comparison between A200 and B200 showed statistically significant differences in the diastolic (64 mm Hg and 68 mm Hg, respectively, P = .001) and mean arterial pressure (86 mm Hg and 89 mm Hg, respectively, P = .031) when data from all the surgical phases were pooled. Additionally, the mouth opening at the suture removal was statistically different for A200 and B200 solutions (91.90% +/- 3.00% and 88.57% +/- 2.38% of the preoperative measure, respectively) when surgeries required bone removal (P < .05). Conclusions: In comparison with 0.5% bupivacaine, 4% articaine (both with 1: 200,000 epinephrine) provided a shorter time to onset and comparable hemostasis and postoperative pain control with a shorter duration of soft tissue anesthesia in lower third molar removal.

Morphodigital study of bone quality in the mandibular angle in patients with third molar impacted

The aim of this study was to analyze if the presence of impacted third molars, and their positions in the mandibular angle, can change the bone quality in this area, considering the measure of the cortical thickness in this region as representative or not for mandible fracture risk. Software was used to analyze 50 digital images from panoramic radiographs of patients who had one or two impacted third molars in the mandible, and 30 digital images of patients with agenesis of the mandibular third molar. The thickness of the cortical region of the mandible was measured; it was possible to draw a parallel line to the posterior portion of the mandible and a parallel line to the body of this bone on each side of the image. At the intersection of these lines near the distal portion of the second molar, another line was set up to serve as reference in the cortical thickness measurement. It could be concluded that the cortical thickness of the mandibular angle in male patients without impacted third molars was greater than the thickness in patients with these teeth, and no difference in thickness was found for the female group.

Histological evaluation of the effectiveness of increased apical enlargement for cleaning the apical third of curved canals

P>Objective To evaluate the influence of apical size on cleaning of the apical third of curved canals prepared with rotary instruments. Methodology Forty-four mesiobuccal canals of maxillary molars teeth were instrumented to different apical sizes (30, 0.02; 35, 0.02; 40, 0.02; 45, 0.02) using a crown-down technique. After canal preparation, the apical thirds of the roots were submitted to histological processing and examination. The specimens were analysed at 40x magnification and the images were submitted to morphometric analysis with an integration grid to evaluate the percentage of debris and uninstrumented root canal walls. The action of the instruments on the root canal walls was assessed based on the surface regularity, abrupt change on the continuity of root canal walls, and partial or total pre-dentine removal. The results were statistically compared using one-way anova with post hoc Tukey test. Pearson`s correlation was performed to identify potential correlations between values. Results The percentage of uninstrumented root canal dentine was higher when apical enlargement was performed with instruments 30, 0.02 taper (55.64 +/- 4.62%) and 35, 0.02 taper (49.03 +/- 5.70%) than with instruments 40, 0.02 taper (38.08 +/- 10.44%) and 45, 0.02 taper (32.65 +/- 8.51%) (P < 0.05). More debris were observed when apical enlargement was performed with instruments 30, 0.02 taper (34.62 +/- 9.49%) and 35, 0.02 taper (25.33 +/- 7.37%) (P < 0.05). There was a significant correlation between the amount of remaining debris and the perimeter of uninstrumented root canal dentine (r = 0.9130, P < 0.001). Conclusion No apical enlargement size allowed the root canal walls to be prepared completely. Apical third cleanliness could be predicted by instrument diameter.

Secondary structure of the third extracellular loop responsible for ligand selectivity of a mammalian gonadotropin-releasing hormone receptor

The extracellular loop 3 (ECL3) of the mammalian gonadotropin-releasing hormone receptor (GnRH-R) contains an acidic amino acid (Glu(301) in the mouse GnRH-R,) that confers agonist selectivity for Are in mammalian GnRH. It is proposed that a specific conformation of ECL3 is necessary to orientate the carboxyl side chain of the acidic residue for interaction with Arg(8) of GnRH, which is supported by decreased affinity for Arg(8) GnRH but not Gln(8) GnRH when an adjacent Pro is mutated to Ala. To probe the structural contribution of the loop domain to the proposed presentation of the carboxyl side chain, we synthesized a model peptide (CGPEMLNRVSEPGC) representing residues 293-302 of mouse ECL3, where Cys and Gly residues are added symmetrically at the N and C termini, respectively, allowing the introduction of a disulfide bridge to simulate the distances at which the ECL3 is tethered to the transmembrane domains 6 and 7 of the receptor. The ability of the ECL3 peptide to bind GnRH with low affinity was demonstrated by its inhibition of GnRH stimulation of inositol phosphate production in cells expressing the GnRH-R. The CD bands of the ECL3 peptides exhibited a superposition of predominantly unordered structure and partial contributions from beta-sheet structure. Likewise, the analysis of the amide I and amide III bands from micro-Raman and FT Raman experiments revealed mainly unordered conformations of the cyclic and of the linear peptide. NMR data demonstrated the presence of a beta-hairpin among an ensemble of largely disordered structures in the cyclic peptide. The location of the turn linking the two strands of the hairpin was assigned to the three central residues L-296, N-297, and R-298. A small population of structured species among an ensemble of predominantly random coil conformation suggests that the unliganded receptor represents a variety of structural conformers, some of which have the potential to make contacts with the ligand. We propose a mechanism of receptor activation whereby binding of the agonist to the inactive receptor state induces and stabilizes a particular structural state of the loop domain, leading to further conformational rearrangements across the transmembrane domain and signal propagating interaction with G proteins. Interaction of the Glu(301) of the receptor with Arg(8) of GnRH induces a folded configuration of the ligand. Our proposal thus suggests that conformational changes of both ligand and receptor result from this interaction.