Browsing by Author "Smith, Mark M."

Now showing 1 - 7 of 7
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    Canine mandibular osteotomy model: the effects of fixation on bone healing and nerve regeneration
    Kern, Douglas A. (Virginia Tech, 1993-04-09)
    Osteotomies made between premolar 3 and premolar 4 in the body of the mandible in canine cadaver hemimandibles (n = 48) were stabilized with five interdental fixation apparatuses in a preliminary biomechanical study. Testing in bending determined ultimate strength, stiffness, and yield strength of the interdental fixation apparatuses. Erich arch bar supplemented with acrylic had significantly (P < 0.05) greater ultimate strength, stiffness, and yield strength than Stout loop supplemented with acrylic, Acrylic, Stout loop, and Erich arch bar alone. Due to the combined superior biomechanical strength of Erich arch bar supplemented with acrylic, it was utilized as the interdental fixation apparatus for the in vivo study. Bilateral osteotomies made between premolar 3 and premolar 4 in the body of the mandible were stabilized with monocortical bone plate (n = 6), interdental (n = 6), and external skeletal fixation (n = 6). None of the dogs showed clinical evidence of pain or discomfort associated with the fixation devices or the development of neuromas. Radiographic signs of bone healing were observed at all osteotomy sites by 16 weeks. Histologic evaluation of bone healing of the mandible with monocortical bone plate, interdental fixation, and external skeletal fixator was not significantly different (P > 0.05) at 8 and 16 weeks postoperatively. The inferior alveolar nerves were evaluated electrophysiologically pre-operatively and at 4, 8, and 16 weeks postoperatively. Nerves were histologically evaluated at 4, 8, and 16 weeks after injury. Nerve function disappeared immediately postoperatively and returned in 64% (24 of 36) by 4 weeks, in 78% (28 of36) by 8 weeks, and 83% (30 of 36) by 16 weeks. Neuromas developed in 100% (36 of 36) of the nerves. Using a transverse osteotomy model, results indicate that the type of bone and nerve healing does not significantly differ between fixation groups tested. Therefore, a simpler and more economical fixation device, Erich arch bar-acrylic, should be suitable to repair selected mandibular fractures in the dog.
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    The effects of indwelling transurethral catheterization and tube cystostomy on urethral anastomoses in dogs
    Cooley, Anjilla Joye (Virginia Tech, 1996-05-05)
    This study compared the effects of urinary diversion by tube cystostomy catheterization, urethral catheterization and tube cystostomy and urethral catheterization on healing urethral anastomoses in the canine urethra. Fifteen intact, mature males were divided into three groups of five dogs. Urodynamic studies were performed under halothane anesthesia preoperatively and at ten weeks postoperatively. Urethral anastomosis was performed in all dogs over a urethral catheter with 4-0 polyglyconate. Group U dogs (n=5) received transurethral catheters. Group C dogs (n=5) received tube cystostomy catheters, and Group B dogs (n=5 ) had both a transurethral catheter and a cystostomy tube placed. All dogs had catheters maintained with a closed urine collection system for seven days. Dogs were observed for ten weeks following surgery, and urinalysis and urine cultures were performed on weeks 1, 4, and 8. Preoperative evaluations were repeated ten weeks postoperatively just prior to termination of the study. Radiographic and histopathologic evaluation of the urethral specimen was performed. No significant differences among the groups were noted after the second postoperative week when comparing observation scores for urination and posturing. Measurements made on in-vivo and in-vitro urethrographic studies revealed less luminal reduction at the anastomotic site in Group C when compared to Groups B and U. Results of this study indicated that urinary diversion by tube cystostomy will minimize the percent luminal diameter reduction (PLDR) when compared to transurethral catheterization alone and tube cystostomy combined with transurethral catheterization. The author recommends tube cystostomy be considered for urinary diversion following primary closure of urethral defects due to the ease of maintenance and increased patient tolerance of the technique.
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    Evaluation of lameness associated with arthroscopy or arthrotomy of the normal canine cubital joint
    Bubenik, Loretta June (Virginia Tech, 2001-04-06)
    This study compared lameness and post-operative recovery in animals undergoing arthroscopy or arthrotomy of the cubital joint. It was a prospective, randomized, experimental study in which fourteen mature, healthy dogs were evaluated. Dogs were randomly assigned to treatment groups with seven undergoing arthrotomy and seven undergoing arthroscopy of the left cubital joint. Dogs were evaluated using kinetic gait assessment, subjective evaluation scores, and cubital joint range of motion (ROM). Evaluations were performed prior to surgery and on days 2, 4, 7, 15, 22, and 29 after surgery. Preoperative radiographs of both cubital joints and postoperative radiographs of the operated limb were evaluated. Significant differences in peak vertical force and vertical impulse force were not observed between surgery groups (p=0.88 and 0.49, respectively). Joint ROM was not significantly different between groups (p = 0.09 for flexion and 0.91 for extension). For all dogs, joint ROM and radiographic evaluations remained within normal range throughout the study period. Additionally, significant differences in subjective lameness scores, weight bearing and pain were not observed between groups (p³ 0.19 for all variables). Therefore, post-operative morbidity may not be an important factor when making a decision to perform either arthroscopy or arthrotomy for exploration of the medial aspect of the canine cubital joint.
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    Ex Vivo Biomechanics of a Bilateral Type I/Bilateral Interdental Pin and Acrylic External Fixator Applied to the Canine Mandible
    Cook, Wesley Todd (Virginia Tech, 2000-06-16)
    Bilateral mandibular ostectomies were performed between premolars 3 and 4 in 10 adult canine specimens. A type I external fixator incorporating a full interdental pin was placed stabilizing a 0.5 cm fracture gap. Four different pin configurations were tested in dorsoventral bending five separate times on each of the ten mandibles: 1) intact mandibular bodies with fixator; 2) ostectomized mandibular bodies and complete fixator; 3) ostectomized mandibular bodies with the caudal pins of the rostral fragment cut; 4) ostectomized mandibular bodies with all pins of the rostral fragment cut. The full interdental pin remained intact in all configurations. Total stiffness and gap stiffness were then determined for each fixation geometry on a materials testing machine. The mean total stiffness(Nm/rads) for the four configurations was 1) 1543.6, 2) 301.6, 3) 290.5, 4) 267.0. The mean gap stiffness(Nm/rads) for the right hemimandible was: 2) 2041.1, 3) 1763.5, 4) 1679.9. The mean gap stiffness of the left hemimandible was: 2) 2110.8, 3)1880.1, 4)1861.1. There was no gap stiffness for the first configuration since a fracture gap was not present. Two-way ANOVA was performed on the gap stiffness and the total stiffness. There was a significant decrease in total stiffness between intact mandibles and ostectomized mandibles regardless of external fixator configuration. However, there was not a significant difference in total stiffness or gap stiffness among the different external fixator configurations applied to ostectomized mandible. External fixator configurations with only the full interdental pin engaging the rostral fragment were as stiff as configurations which had two or four additional pins in the rostral fragment for the applied loads. External fixators for rostral mandibular fractures may be rigidly secured with rostral fragment implants applied extracortically avoiding iatrogenic trauma to teeth and tooth roots.
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    Periodontal Healing of Canine Experimental Grade III Furcation Defects Treated With Autologous Fibrinogen and Resolut® Barrier Membrane
    Bianucci, Henri Chapman Jr. (Virginia Tech, 1998-05-26)
    Experimental grade III furcation defects were developed bilaterally at the second and fourth premolars in 18 conditioned, laboratory-source, adult Beagles and maintained for 12 weeks. All defects were treated with debridement and mucoperiosteal flap repositioning alone, or with the addition of autologous fibrinogen, Resolut® barrier membrane, or autologous fibrinogen and Resolut® barrier membrane. The defects were analyzed by digital subtraction radiography, histopathologic, and histomorphometric analysis of healing at 1, 3, and 6 months post-treatment to determine: percent increase in defect bone volume, height and area, and length of periodontal regeneration along the perimeter of the defect. Comparisons at post-treatment intervals indicated significantly (P < 0.05) greater healing of debridement and autologous fibrinogen treated defects at 3 months, however by 6 months there were no significant differences in defect healing for all histomorphometric parameters. Defects receiving Resolut® were associated with significantly less root ankylosis. Defects receiving debridement alone had significantly greater increases in bone volume, as calculated with digital subtraction radiography, at 6 months post-treatment compared with groups receiving Resolut®. There was a significant correlation between regenerated bone area, bone volume, and periodontal regeneration for all treatments at 3 and 6 months post-treatment. In this study autologous fibrinogen and Resolut® barrier membrane did not enhance the amount of periodontal healing compared with debridement only. However, Resolut® treated defects were essentially absent of root ankylosis. Therefore, canine periodontitis causing grade III furcation involvement may respond equally well to conservative periodontal surgery compared with guided tissue regenerative techniques. However, the prevention of root ankylosis may provide a substantial benefit favoring this latter methodology.
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    Risk Factors for Failure of Hard Palate Mucoperiosteal Flap Repair of Acquired Oronasal Communication in Dogs: A Pilot Study
    Taney, Kendall; Smith, Mark M.; Cummings, Nathan P.; Lozano, Alicia J. (2021-11-03)
    The objective of this retrospective pilot study was to describe potential risk factors for failure of hard palate mucoperiosteal flaps (HPF) transposed for closure of oronasal communication. Dogs (n = 28) with acquired oronasal communication defects were included in the study population. Functional success of an HPF was determined by visual inspection at the last examination and lack of clinical signs. Risk factors for HPF failure including age, sex, body weight, presence of neoplasia at the time of surgery, presence of neoplasia after surgery due to incomplete or narrow margins, use of CO2 laser, previous surgeries in the same location, HPF blood supply, size of the HPF as a percentage of the total area of the hard palate mucoperiosteum, and distance traveled by the apex of the HPF were evaluated using descriptive statistics and unadjusted logistic regression modeling. Seven out of 28 (25%) hard palate flap procedures resulted in persistent oronasal communication and were considered failures. Body weight (Median: 17 vs. 25 kg, OR = 0.94, 80% CI = 0.90, 0.99), presence of neoplasia at the time of surgery (86 vs. 57%, OR = 4.50, 80% CI = 1.01, 20.06), HPF area (Median: 0.49 vs. 0.41, OR = 84.40, 80% CI = 1.66, 4,298) and apex travel distance (Median: 2.06 vs. 0.67, OR = 5.15, 80% CI = 2.14, 12.38) were associated with flap failure. Within this sample, the presence of neoplasia at the time of initial surgery, increasing the area of the HPF, and distance traveled by the HPF apex were associated with a greater odds of HPF failure. Further studies with larger sample sizes are needed to confirm repeatability of these results. HPFs remain a viable surgical option for closure of oronasal communication. Careful surgical planning, strict adherence to surgical principles, and awareness of anatomical limitations can increase the likelihood of success.
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    Superficial temporal artery flap: its development and application in the dog and cat
    Fahie, Maria Aline (Virginia Tech, 1996-04-15)
    Cutaneous arterial blood supply to the temporal region was evaluated in 8 dogs and 8 cats. Dissection of 4 dog and 4 cat cadavers revealed the location of cutaneous branches of the superficial telnporaJ artery supplying the frontalis tnuscle and skin of the temporal region. The frontalis 1l1uscle is a thin muscle dorsal to the temporaJis muscle that extends cranially and rostral1y from the rostral border of the scutulU111 to the forehead and upper eyelid. Microangiography and subtraction radiography of the external carotid and superficial telnporal arteries were used in 4 dogs and 4 cats to determine arterial blood supply to the temporal region and frontalis muscle. A superficial temporal artery (ST A) flap was developed in 9 dogs [ group A (n=5), group B (n=4)]. Ligation of the superficial tetnporal artery in the control dogs (n=5), rendered flaps dependent on the subdermal plexus. Dogs in group A (n=5) and the control group (n=5) had flap lengths that extended to the contralateral eye, while group B (n=4) flaps extended to the contralateral zygomatic arch. A11 flap widths were equivalent to the width of the zygomatic arch in the individual dog. Mean length of surviving tissue (mean survival length) (+/- SD) of control flaps was 7.0 (0.6) ern, compared with experimental flaps, group A 9.) (0.8) em and group B 10.4 0.1) cm. Mean survival percentage area of control flaps was 73.5 (7.4) %, compared with experimental flaps, group A 93.1 (7.5) 0/0 and group B 69.1 (4.5) 0/0. The mean survival length of control and experimental flaps was significantly different (P < 0.05). There was no significant difference between survival lengths of the experimental groups.