Investigation of a maxillary nerve block technique in guinea pigs (Cavia porcellus): A cadaveric study comparing two injectate volumes.

OBJECTIVE: To investigate and describe an extraoral approach to perform a maxillary nerve block in guinea pigs. STUDY DESIGN: Prospective, randomized, blinded, descriptive, cadaveric study. ANIMALS: A total of 14 adult guinea pig cadavers. METHODS: Two cadavers were used for anatomic dissection and determination of maxillary nerve block approach. A maxillary nerve block via infraorbital approach was then performed in 12 cadavers. A low volume (0.1 mL) or high volume (0.2 mL) of diluted methylene blue injectate was randomly assigned to the right or left side, with the other volume used for the contralateral side. The maxillary nerve was dissected after each injection by an investigator blinded to injectate volume. The region of dye distribution was identified, and the degree of staining assigned an accuracy score (0-2). Nerve coverage was considered adequate if ≥6 mm of circumferential staining was present. RESULTS: Accuracy evaluation indicated successful dye deposition in 10/12 [2 (0-2), median (range)] injections in the low volume group and 8/12 [2 (1-2)] injections in the high volume group. The majority (79.2%) of injections resulted in adequate nerve staining. There were no statistically significant differences between injectate volumes for accuracy (p = 0.64) or adequacy (p > 0.99) of staining. CONCLUSIONS: The infraorbital approach is a simple and practical method for maxillary nerve blockade in guinea pigs. An injectate volume of 0.1 mL results in adequate maxillary nerve coverage; however, additional studies are needed to assess the efficacy in clinical use.

Investigation into a Conformationally Locked (Z)-Azidoxime.

High nitrogen compounds find wide use in the development of new propellants and explosives as well as pharmaceutical chemistry as bioisosteres, bacterial stains, and antifungal agents. A class of underexplored high-nitrogen materials includes azidoximes and their 1-hydroxytetrazole isomers. Azidoximes possess an energetic azide group and are quite sensitive to impact, spark, and friction. Therefore, these materials are generated in situ and cyclized under mild acidic conditions to their 1-hydroxytetrazole isomers. Recently, we synthesized a novel 1,2,4-triazine-derived azidoxime; however, upon subjecting this material to established cyclization conditions, no reaction was observed, even after prolonged reaction times with heating. Additional 1,2,4-triazine-derived azidoximes also displayed a similar lack of reactivities. This observation led us to probe the reactivity of these materials with both a DFT investigation and crystallographically based electrostatic potential mapping. In all, the lack of reactivity toward cyclization was found to be due to an inability of 1,2,4-triazine-based azidoximes to isomerize into the reactive (E)-conformation, requiring an activation energy of 26.4 kcal mol-1.

Evaluation of Perceived Technical Skill Development by Students During Instruction in Dental Extractions in Different Laboratory Settings-A Pilot Study.

In veterinary general practice, dental extractions are common procedures that require a specific set of surgical skills. Veterinary medical educators are tasked with preparing students for general practice, equipping them with medical knowledge and surgical skills. Results of this pilot study demonstrate students' preference for circle-based laboratory setup, a perceived high value of immediate feedback when performing laboratory exercises, and a lack of preference for timing of the laboratory relative to the relevant material provided in lecture. The impact of lecture, supplemental information, and laboratory setup on development of these surgical skills are explored.

A Volumetric Assessment Using Computed Tomography of Canine and First Molar Roots in Dogs of Varying Weight.

Mandibular volume and tooth root volumes were shown to increase at different rates at locations containing the roots of the canine (C) and mesial and distal roots of the first molar (M1). Thirty-six dogs were included in this study. Data were generated using computed tomography at locations of the mandible involving the roots of the C and M1 teeth. Software was used to trace the external surface of the mandible, calculating the volume of the mandible at each location. Similar techniques were used to trace and calculate the volume of the C and M1 roots. Mandible volume, tooth root volume, and root percentage of mandible volume were analyzed and compared using the slopes of the best fit line. At the M1 mesial and distal roots, mandible volume ( P < .001) and root volume ( P < .001) were both noted to increase, with increasing weight at different rates. The rate of change in the root percentage by weight of M1 roots was not different ( P = .214). Each location demonstrated a different increasing rate of change for mandibular volume and increasing root volume. Results show that as patient's weight increases, the mandible and root volumes increase at different rates. Root percentage by volume at all three locations was noted to decrease by the same rate. Canine and M1 roots are proportionally larger than the supporting mandibular bone in smaller patients. Care should be taken to recommend periodontal disease prevention for owners of small dogs and consideration made when performing extractions or other surgery that may destabilize the mandible.

Simple and Efficient Synthesis of Explosive Cocrystals containing 3,5-Dimethylpyrazol-1-yl-substituted-1,2,4,5-tetrazines.

The reaction of 3,4-dinitropyrazole, 5-nitrotetrazole, or 4-nitro-1,2,3-triazole with 1,2,4,5-tetrazines substituted with 3,5-dimethylpyrazolyl (dmp) groups results in energetic cocrystals after 1 minute of reflux and cooling to room temperature in yields of 89-92 %. Hydrogen-bonding between the dmp group to the N-H of the energetic heterocycles are the predominant interaction that stabilizes the new cocrystals. Each cocrystal packs in a different lattice structure and the cocrystals with sheet-like and herring-bone crystal packing orientations are less sensitive than the cocrystal with the interlocked structure. Electrostatic potential mapping helps rationalize why dmp-substituted tetrazines readily form cocrystals, whereas more electron-deficient pyrazolyl tetrazines do not. The calculated energetic performance of the new cocrystals approaches that of 2,4,6-trinitrotoluene (TNT) and importantly, these materials will aid in the rational design of new cocrystalline energetic materials.

Synthesis and Electrochemical Behavior of Electron-Rich s-Tetrazine and Triazolo-tetrazine Nitrate Esters.

We have prepared energetic nitrate ester derivatives of 1,2,4,5-tetrazine and 1,2,4-triazolo[4,3-b]-[1,2,4,5]-tetrazine ring systems as model compounds to study the electrochemical behavior of tetrazines in the presence of explosive groups. The model compounds showed lower thermal stabilities relative to PETN (pentaerythritol tetranitrate), but slightly improved mechanical sensitivities. The presence of electron-rich amine donors leads to a cathodic shift of the tetrazine redox potentials relative to those of previously reported tetrazine explosives. At these potentials, electron-rich tetrazines with either covalently bound or co-dissolved nitrate ester groups are irreversibly reduced. Effectively, changes in the electronic structure of tetrazines affect their electrochemical response to the presence of nitrate ester groups. Thus, it may be possible to develop tetrazine-based electrochemical sensors for the detection of specific explosives and electrocatalysts for their disposal.

Caudal Mandibular Bone Height and Buccal Cortical Bone Thickness Measured by Computed Tomography in Healthy Dogs.

OBJECTIVE: To characterize bone height and buccal cortical bone thickness of the caudal mandible of healthy dogs. STUDY DESIGN: Prospective original study. SAMPLE POPULATION: Client-owned dogs (n = 36). METHODS: Dogs were distributed by weight into 3 groups (<10, 10-20, >20 kg). Thirteen transverse plane computed tomography images were selected for each dog based on anatomic landmarks from the 4th premolar (PM4) through the 2nd molar. On each image, bone thickness was measured along the buccal surface of both mandibles from the alveolar margin to the ventral border in 3 mm increments. The number of 3 mm increments were recorded as an estimation of mandibular height. RESULTS: Buccal bone was generally thicker ventrally in the area studied with decreasing bone thickness over both roots of PM4 and the mesial root of the 1st molar (M1). Cortical bone thickness of <2.0 mm was measured across all groups at most locations 3 mm ventral from the alveolar margin. Mandibular bone height demonstrated significantly fewer (P < .05) 3 mm increments over the distal root of M1 in dogs >10 kg compared with the number of observations at the immediately mesial and distal locations. CONCLUSION: Thin cortical bone overlying the mesial and distal roots of PM4 and the mesial root of M1 limits use of these areas for application of monocortical anchorage devices. Decreased mandibular bone height at mandibular M1 may create a stress riser at this location, which along with thin cortical bone may explain why this is a common area for mandibular fracture.

Effects of Buprenorphine Added to Bupivacaine Infraorbital Nerve Blocks on Isoflurane Minimum Alveolar Concentration Using a Model for Acute Dental/Oral Surgical Pain in Dogs.

Bupivacaine appears to have a duration of action longer than previously reported. Results of this study demonstrate that the addition of buprenorphrine may enhance the analgesic duration of effect for bupivacaine regional nerve blocks. In addition, the use of bupivacaine alone may have analgesia that exceeds 24 hours in many cases. Although not statistically significant based on sample size, 50% of dogs receiving the bupivacaine/buprenorphine regional anesthetic block demonstrated a decreased anesthetic requirement 48 hours postadministration when compared to 25% of dogs receiving the bupivacaine anesthetic. No adverse cardiorespiratory effects were noted secondary to either local anesthetic treatment. Use of bupivacaine may have analgesic effects extending greater than 24 hours (24-72) when used in regional anesthetic blocks in veterinary dental patients with acute dental pain. The addition of buprenorphine to bupivacaine may extend the duration of analgesia (48-96 h). The limited sample size, in addition to patient variability in response to medications, may account for the fact that no differences were detected between the treatments administered.

Successful Treatment of Mandibular Nonunion With Cortical Allograft, Cancellous Autograft, and Locking Titanium Miniplates in a Dog.

Discontinuities of the mandible can occur for a variety of reasons including primary pathology of bone, pathologic fracture secondary to periodontal disease, and segmental resection for the treatment of neoplasia. Surgical intervention is necessary in many cases to establish normal occlusion and normal mandibular function. Rigid stabilization and treatment of these defects can be challenging due to the limited availability of bone for fixation as well as limited soft tissue coverage. This case report describes successful treatment of a nonunion fracture using cortical allograft and locking titanium miniplates. Complete osseointegration and bone healing were achieved, allowing for complete return to normal occlusion and function.

Transmylohyoid orotracheal intubation in surgical management of canine maxillofacial fractures: an alternative to pharyngotomy endotracheal intubation.

OBJECTIVE: To describe the surgical technique of transmylohyoid orotracheal intubation in surgical management of maxillofacial fractures in dogs. STUDY DESIGN: Case series. ANIMALS: Dogs (n = 4) with maxillofacial fractures. METHODS: Transmylohyoid orotracheal intubation was used for airway management of dogs undergoing surgical repair of maxillofacial trauma. A stoma was surgically created by an incision through the skin, subcutaneous tissue, and mylohyoideus muscle immediately medial to the lingual cortex of the mandible at the level of the mandibular 1st molar tooth, so that an endotracheal tube could exit the oral cavity between the mandibular bodies bypassing the dentition. RESULTS: Transmylohyoid orotracheal intubation allowed excellent surgical visibility of the oral cavity and intraoperative control of occlusion during surgery. No complications were encountered during the procedure and the stoma healed without complication. CONCLUSIONS: Transmylohyoid orotracheal intubation is a safe, simple, and effective technique for bypassing the rostral oral cavity and dentition during surgical management of maxillofacial fractures.

Comparison of the Diagnostic Image Quality of the Canine Maxillary Dentoalveolar Structures Obtained by Cone Beam Computed Tomography and 64-Multidetector Row Computed Tomography.

The objective of this blinded study was to validate the use of cone beam computed tomography (C) for imaging of the canine maxillary dentoalveolar structures by comparing its diagnostic image quality with that of 64-multidetector row CT Sagittal slices of a tooth-bearing segment of the maxilla of a commercially purchased dog skull embedded in methylmethacrylate were obtained along a line parallel with the dental arch using a commercial histology diamond saw. The slice of tooth-bearing bone that best depicted the dentoalveolar structures was chosen and photographed. The maxillary segment was imaged with cone beam CT and 64-multidetector row CT. Four blinded evaluators compared the cone beam CT and 64-multidetector row CT images and image quality was scored as it related to the anatomy of dentoalveolar structures. Trabecular bone, enamel, dentin, pulp cavity, periodontal ligament space, and lamina dura were scored In addition, a score depicting the evaluators overall impression of the image was recorded. Images acquired with cone beam CT were found to be significantly superior in image quality to images acquired with 64-multidetector row CT overall, and in all scored categories. In our study setting cone beam CT was found to be a valid and clinically superior imaging modality for the canine maxillary dentoalveolar structures when compared to 64-multidetector row CT.

Effect of preparation surface area on the clinical outcome of full veneer crowns in dogs.

Crown therapy is commonly used in veterinary medicine to provide support to teeth which have previously fractured, received root canal therapy, have significant wear, or experienced other detrimental removal of tooth substance. As with several aspects of veterinary medicine, many of the recommendations or guidelines for crown therapy originate from human dentistry, which are then transferred to veterinary patients. Due to the significant difference in the anatomy of teeth and function of the oral cavity between humans and dogs, these guidelines need to be studied to determine the appropriateness of their use in veterinary patients. This article evaluates the relationship between surface area of the preparation and clinical outcome of full veneer crown therapy of the canine tooth in dogs. Although there appeared to be a positive relationship between preparations with greater surface area and successful clinical outcome, it was not found to be statistically significant.

Clinicopathologic characterization of oral pyogenic granuloma in 8 cats.

This case series characterizes the clinicopathologic features and treatment of oral pyogenic granuloma in 8 cats. The cats reported here were patients originating from collaborative efforts at an academic clinical teaching hospital and a specialty dentistry/oral surgery referral practice. Although the initial biopsy results were variable, in all cases the diagnosis reflected an inflammatory process. A second clinicopathologic evaluation of these cases determined that all lesions were consistent with oral pyogenic granuloma. The location of the lesion was consistent among all cats within the present study Lesions developed at the vestibular mucogingival tissues of the mandibular first molar teeth. We propose that malocclusion and secondary traumatic contact of the ipsilateral maxillary fourth premolar tooth with the mandibular soft tissues is a possible contributing factor in the etiopathogenic mechanism.

Temporomandibular Joint Gape Angles in Normal and Painful Domestic Felines.

The purpose of this study was to determine and compare the gape angles (temporomandibular joint range of motion with mouth opening) of conscious and anesthetized domestic felines and to compare gape angles with and without evidence of oral pain. This prospective study evaluated the gape angle of 58 domestic felines. The cats were grouped into painful (n = 33) and nonpainful cohorts (n = 25) and gape angles were compared during conscious and anesthetized conditions. Gape angles were determined based on measurements of the maximal interincisal distance and lengths of the mandible and maxilla followed by calculation of the law of cosines. The mean feline gape angle (standard deviation) was determined to be 45.3° (8.6°) and 50.8° (6.2°) for conscious and anesthetized felines respectively. There was no significant difference between painful and non-painful feline gape angles during conscious (P = .613) or anesthetized (P = .605) evaluations. There was a significant difference between anesthetized and conscious gape angles (P < .001) for both painful and non-painful cohorts. This study determined the standardized, normal feline temporomandibular joint (TMJ) gape angle in both conscious and anesthetized states. This study suggests that the feline gape angle is not a useful indicator of oral pain. By determining the feline gape angle, which was previously unknown, further evaluation of its utility as a non-invasive clinical parameter for evaluation of restrictive TMJ motions as well as its use for serial evaluations may be pursued.

Synthesis, structure, and properties of group 1 metal complexes containing nitrogen-rich hydrotris(tetrazolyl)borate ligands.

Nitrogen-rich hydrotris(tetrazolyl)borate salts of lithium, sodium, and potassium have been prepared for the first time by thermolysis of the borohydride ion with three equivalents of tetrazoles in ether solvents at 160-162 °C. Despite the high nitrogen contents, these complexes have low sensitivity to impact, electrostatic discharge, and friction.

Clinical, histologic, and computed tomographic features of oral papillary squamous cell carcinoma in dogs: 9 cases (2008- 2011).

Medical records of dogs diagnosed with oral papillary squamous cell carcinoma between December 2008 and April 2011 were reviewed. Information abstracted included signalment, tumor location, tumor size, computed tomographic (CT) features, evidence of metastatic disease based on cytologic examination of lymph node aspirates and thoracic radiography, treatment, surgical margins, histologic features, and treatment outcome. Dogs included in the study were all sexually altered, predominantly large breed dogs with a mean age of 3.9-years (range, 0.5 to 9.0-years). The most common location was the rostral maxilla. Invasion of underlying bone and lymphadenopathy were evident on CT imaging in most dogs. No evidence of metastasis was found on mandibular lymph node cytology and thoracic radiography. Histologic analysis revealed similar morphologic findings for all surgically resected tumors. Surgical excision with 1-2 cm margins was complete in all cases, with a mean tumor-free interval of 12.1-months.

Synthesis and Energetic Properties of N-Substituted 3,4- and 3,5-Dinitropyrazoles.

3,4- and 3,5-Dinitropyrazoles (DNPs) were substituted with acryl and allyl groups on the N1 nitrogen atom, resulting in three novel energetic materials. These compounds are all liquids at room temperature with melting points ranging from -60.2 to -38.6 °C and were fully characterized by high-resolution mass spectrometry, elemental analysis, proton and carbon nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. These materials were also tested for electrostatic discharge, friction, and impact sensitivities and then compared to DNP starting materials and to the explosive nitroglycerin (NG). These results indicate that the synthesized compounds are less sensitive to impact compared to NG and have higher thermal stabilities to decomposition.

Synthesis, Characterization, and Energetic Properties of Nitrate Ester Acrylate Polymer.

An energetic nitrate ester acrylate monomer (4) was synthesized in a total yield of 68% and polymerized to form the energetic nitrate ester acrylate polymer (NEAP). Compound 4 is a liquid at room temperature with a melting point of -8.6 °C and NEAP is a solid with a glass-transition temperature of -8.8 °C. Intermediates leading to 4 and NEAP were characterized by high-resolution mass spectrometry, elemental analysis, Fourier transform infrared spectroscopy, and proton and carbon nuclear magnetic resonance spectroscopies (1H and 13C{1H} NMR). Both 4 and NEAP have electrostatic discharge, friction, and impact sensitivities comparable to those of trinitrotoluene, making NEAP a potential candidate for advanced energetic formulations.

Radiolytic degradation of dodecane substituted with common energetic functional groups.

Explosives exist in and are expected to withstand a variety of harsh environments up to and including ionizing radiation, though little is known about the chemical consequences of exposing explosives to an ionizing radiation field. This study focused on the radiation-induced chemical changes to a variety of common energetic functional groups by utilizing a consistent molecular backbone. Dodecane was substituted with azide, nitro, nitrate ester, and nitramine functional groups and γ-irradiated with 60Co in order to study how the functional group degraded along with what the relative stability to ionizing radiation was. Chemical changes were assessed using a combination of analysis techniques including: nuclear magnetic resonance (NMR) spectroscopy, gas chromatography of both the condensed and gas phases, Raman spectroscopy, and Fourier transform infrared (FTIR) spectroscopy. Results revealed that much of the damage to the molecules was on the energetic functional group and often concentrated on the trigger linkage, also known as the weakest bond in the molecule. The general trend from most to least susceptible to radiolytic damage was found to be D-ONO2 → D-N3 → D-NHNO2 → D-NO2. These results also appear to be in line with the relative stability of these functional groups to things such as photolysis, thermolysis, and explosive insults.

Use of an autogenous cortical graft in combination with guided tissue regeneration for treatment of an infrabony defect.

Infrabony periodontal defects are common findings encountered during complete oral examinations. Treatment options for infrabony lesions are aimed at meeting client demands as well as patient needs. Deciding on how to treat these lesions depends on the nature and degree of disease present as well as having the materials available to improve the chances of achieving the greatest clinical success. Bone grafting of an infrabony defect of the left mandibular first molar tooth of a dog using an autogenous cortical graft harvested with a reusable bone grafter in combination with guided tissue regeneration is described.