OBJECTIVE To compare the biomechanical behavior of mandibular critical-sized defects stabilized with 2 plating configurations under in vitro conditions resembling clinical situations.
SAMPLE 24 mandibles harvested from 12 adult canine cadavers.
PROCEDURES 8 mandibles were kept intact as control samples. A critical-sized defect was created in 16 mandibles; these mandibles were stabilized by use of a single locking plate (LP [n = 8]) or an LP combined with an alveolar miniplate (LMP ). Mandibles were loaded in cantilever bending in a single-load-to-failure test with simultaneous recording of load and actuator displacement. Stiffness, yield, and failure properties were compared among groups. Mode of failure was recorded. Radiographic evidence of tooth root and mandibular canal damage was quantified and compared between groups.
RESULTS Stiffness and yield loads of single LP and LMP constructs were < 30% of values for intact mandibles, and failure loads were < 45% of values for intact mandibles. There were no consistent biomechanical differences at failure between single LP and LMP constructs, but the LMP construct had greater stiffness and strength prior to yield. Frequency of screw penetration of teeth and the mandibular canal was significantly greater for LMP than for single LP constructs.
CONCLUSIONS AND CLINICAL RELEVANCE Both fixation methods were mechanically inferior to an intact mandible. The LMP construct was mechanically stronger than the LP construct but may not be clinically justifiable. Addition of an alveolar miniplate provided additional strength to the construct but resulted in more frequent penetration of tooth roots and the mandibular canal.
Objective—To document the short- and long-term outcomes of surgical endodontic treatment in dogs in a clinical setting.
Design—Retrospective case series.
Animals—15 dogs that underwent surgical endodontic treatment.
Procedures—Medical records of dogs that underwent surgical endodontic treatment at 3 institutions from January 1995 to December 2011 were reviewed. Information extracted included signalment, history, initial clinical signs, physical and radiographic examination findings, treatment, and outcome. Outcome was determined through evaluation of the pre- and postoperative radiographs as well as clinical and radiographic findings at follow-up evaluations. On the basis of radiographic findings, treatment was considered successful if the periapical lesion and bone defect created by surgery had completely healed and no new root resorption was detected; a treatment was considered to have no evidence of failure if the periapical lesion remained the same or had not completely resolved and root resorption was static.
Results—15 dogs were treated by means of apicoectomy and retrograde filling following a failed or complicated orthograde root canal treatment. The mean long-term follow-up time was 15.2 months (range, 3 to 50 months). On radiographic evaluation, 10 of 15 dogs had successful resolution of the periapical disease; 5 dogs had no radiographic evidence of failure of endodontic treatment. All dogs were considered to have a successful clinical outcome.
Conclusions and Clinical Relevance—Surgical endodontic treatment was an effective option for salvaging endodontically diseased but periodontally healthy teeth of dogs in which orthograde treatment was unsuccessful and nonsurgical retreatment was unlikely to succeed.
OBJECTIVE To evaluate biomechanical properties of intact feline mandibles, compared with those for mandibles with an experimentally created osteotomy that was stabilized with 1 of 2 internal fixation configurations.
SAMPLE 20 mandibles from 10 adult feline cadavers.
PROCEDURES An incomplete block study design was used to assign the mandibles of each cadaver to 2 of 3 groups (locking plate with locking screws [locking construct], locking plate with nonlocking screws [nonlocking construct], or intact). Within each cadaver, mandibles were randomly assigned to the assigned treatments. For mandibles assigned to the locking and nonlocking constructs, a simple transverse osteotomy was created caudal to the mandibular first molar tooth after plate application. All mandibles were loaded in cantilever bending in a single-load-to-failure test while simultaneously recording load and actuator displacement. Mode of failure (bone or plate failure) was recorded, and radiographic evidence of tooth root and mandibular canal damage was evaluated. Mechanical properties were compared among the 3 groups.
RESULTS Stiffness, bending moments, and most post-yield energies for mandibles with the locking and nonlocking constructs were significantly lower than those for intact mandibles. Peak bending moment and stiffness for mandibles with the locking construct were significantly greater than those for mandibles with the nonlocking construct. Mode of failure and frequency of screw damage to tooth roots and the mandibular canal did not differ between the locking and nonlocking constructs.
CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that both fixation constructs were mechanically inferior to intact mandibles. The locking construct was mechanically stronger than the nonlocking construct.
Objective—To identify risk factors associated with survival in dogs with nontonsillar oral squamous cell carcinoma (OSCC) that were and were not treated with curative-intent surgery.
Design—Retrospective case series.
Animals—31 dogs with OSCC.
Procedures—Medical records for dogs with OSCC that were not treated, or were treated with curative-intent surgery only between January 1990 and December 2010 were reviewed. For each dog, data regarding signalment, clinical stage, treatment, tumor recurrence, and survival time were obtained from the medical record, and archived biopsy specimens were evaluated to identify the histologic subtype of the tumor and extent of tumor-associated inflammation (TAI), perineural invasion (PNI), and lymphovascular invasion (LVI).
Results—Risk of death for the 21 dogs with OSCC that were surgically treated was decreased 91.4% (hazard ratio, 0.086; 95% confidence interval, 0.002 to 0.150), compared with that for the 10 dogs with OSCC that were not treated. The 1-year survival rate was 93.5% and 0% for dogs that were and were not surgically treated, respectively. Risk of death increased significantly with increasing TAI and increasing risk score (combination of TAI, PNI, and LVI). Tumor location, clinical stage, and histologic subtype were not associated with survival time.
Conclusions and Clinical Relevance—Results indicated that the prognosis for dogs with OSCC was excellent following surgical excision of the tumor. Risk of death increased with increasing TAI, and combining TAI, PNI, and LVI into a single risk score may be a useful prognostic indicator for dogs with OSCC.
Objective—To evaluate factors associated with the outcome of vital pulp therapy (VPT) in dogs.
Sample—190 teeth in 138 dogs.
Procedures—Medical records were reviewed; radiographs obtained before, immediately after, and during the last available follow-up examination for VPT were evaluated. Treatment was categorized as successful (with radiographic evidence of continued secondary dentin production, continued root formation in immature teeth, and absence of clinical and radiographic signs of apical periodontitis and internal or external inflammatory root resorption), having no evidence of failure (with signs for success fulfilled except the width of the apical periodontal ligament space, which could be wider than but no more than double the width of the periodontal ligament space in other areas), or failed (with radiographic evidence of pulp necrosis, apical periodontitis, or inflammatory root resorption). Associations between diagnostic or treatment-related variables and outcome were assessed with multinomial logistic regression.
Results—Overall, treatment was classified as successful for 162 of 190 (85%) teeth, including 23 (12%) teeth with no evidence of failure, and as having failed for 28 (15%) teeth. The overall success rate was 137 of 149 (92%) for teeth treated with mineral trioxide aggregate alone and 21 of 36 (58%) for teeth treated with Ca(OH)2 alone. Use of Ca(OH)2 and deep penetration of dressing material into the vital pulp were each significantly associated with increased odds of treatment failure.
Conclusions and Clinical Relevance—Results indicated that VPT with mineral trioxide aggregate was an effective option for use in crown reduction to treat malocclusion and for treatment of recent crown fractures in immature or mature permanent teeth.
Objective—To develop a computer-assisted image
analysis procedure for quantitation of neovascularization
in formalin-fixed paraffin-embedded specimens
of thyroid gland tissue from dogs with and
without thyroid gland neoplasia.
Sample Population—47 thyroid gland carcinomas,
8 thyroid gland adenomas, and 8 specimens of thyroid
tissue from dogs without thyroid gland abnormalities
Procedure—Serial tissue sections were prepared
and stained with antibodies against human CD31 or
factor VIII-related antigen (factor VIII-rag). The areas
of highest vascularity were identified in CD31-
stained sections, and corresponding areas were
then identified in factor VIII-rag-stained sections.
Image analysis was used to calculate the total vascular
density in each section, and neovascularization,
expressed as a percentage, was determined
as the absolute value of the total vascular density
derived from factor VIII-rag-stained sections minus
the vascular density derived from CD31-stained
Results—Mean vascular density of thyroid gland
carcinomas derived from CD31-stained sections
was significantly greater than density derived from
factor VIII-rag-stained sections. This incremental difference
was presumed to represent degree of neovascularization.
However, significant differences
were not detected between vascular densities
derived from CD31 and factor VIII-rag-stained sections
for either normal thyroid gland tissue or thyroid
gland adenomas. No significant correlations
were found between vascular density in thyroid
gland carcinomas and survival time following
Conclusion and Clinical Relevance—A computerassisted
image analysis method was developed for
quantifying neovascularization in thyroid gland
tumors of dogs. This method may allow identification
of dogs with tumors that are most likely to
respond to treatment with novel antiangiogenesis
agents. (Am J Vet Res 2002;63:363–369)
To evaluate and quantify the kinematic behavior of canine mandibles before and after bilateral rostral or unilateral segmental mandibulectomy as well as after mandibular reconstruction with a locking reconstruction plate in ex vivo conditions.
Head specimens from cadavers of 16 dogs (range in body weight, 30 to 35 kg).
Specimens were assigned to undergo unilateral segmental (n = 8) or bilateral rostral (8) mandibulectomy and then mandibular reconstruction by internal fixation with locking plates. Kinematic markers were attached to each specimen in a custom-built load frame. Markers were tracked in 3-D space during standardized loading conditions, and mandibular motions were quantified. Differences in mandibular range of motion among 3 experimental conditions (before mandibulectomy [ie, with mandibles intact], after mandibulectomy, and after reconstruction) were assessed by means of repeated-measures ANOVA.
Both unilateral segmental and bilateral rostral mandibulectomy resulted in significantly greater mandibular motion and instability, compared with results for intact mandibles. No significant differences in motion were detected between mandibles reconstructed after unilateral segmental mandibulectomy and intact mandibles. Similarly, the motion of mandibles reconstructed after rostral mandibulectomy was no different from that of intact mandibles, except in the lateral direction.
CONCLUSIONS AND CLINICAL RELEVANCE
Mandibular kinematics in head specimens from canine cadavers were significantly altered after unilateral segmental and bilateral rostral mandibulectomy. These alterations were corrected after mandibular reconstruction with locking reconstruction plates. Findings reinforced the clinical observations of the beneficial effect of reconstruction on mandibular function and the need for reconstructive surgery after mandibulectomy in dogs.
To evaluate the biomechanical properties of the mandibles of cats with experimentally created osteotomies simulating oblique ramus fractures, which were stabilized with malleable L-miniplates with either locking screws [locking construct (LC)] or nonlocking screws [nonlocking construct (NLC)], compared with those for intact mandibles.
20 mandibles from 10 adult cat cadavers.
A block study design was adopted to allocate the mandibles of each cadaver to 2 of the 3 test groups (LC, NLC, or intact mandible). Mandibles within each cadaver were allocated systematically to a test group. For mandibles assigned to an LC and an NLC, a complete oblique osteotomy was performed from the mid rostral aspect of the ramus in a caudoventral direction. All mandibles were loaded in a single-load-to-failure test through cantilever bending. Load and actuator displacement were recorded simultaneously. Mode of failure and radiographic evidence of damage to tooth roots and the mandibular canal were evaluated. Biomechanical properties were compared among the groups.
No iatrogenic tooth root damage was evident, but all mandibles with an LC and an NLC had evidence of screw invasion into the mandibular canal. Plated mandibles had significantly less stiffness and bending moment than intact mandibles. Stiffness was not significantly different between the LC and the NLC; the NLC had a greater bending moment at failure than the LC. The pre-yield stiffness of plated mandibles decreased when the number of screw holes overlapping the mandibular canal increased.
The use of a malleable L-miniplate in a caudal mandibular fracture model is feasible. Both the LC and the NLC were inferior mechanically to intact mandibles. Type of construct used did not affect the construct stiffness significantly in tested mandibles.
Objective—To describe clinical features of oral and maxillofacial osteomas in cats.
Design—Retrospective case series.
Animals—7 cats with oral or maxillofacial osteoma or both.
Procedures—Medical records were reviewed for information on signalment, history, clinical signs, physical examination findings, diagnostic imaging findings, results of serum biochemical analyses and histologic testing, surgical procedures performed, and perioperative complications. Outcome was determined on the basis of follow-up telephone interviews of owners.
Results—Cats ranged from 1 to 23 years of age. Clinical signs were observed in 5 cats and were attributed to the presence of the mass. Diagnostic imaging (radiography and computed tomography) and histologic examination confirmed the diagnosis of osteoma. Three cats were euthanatized; 1 cat was treated by mandibulectomy, 1 was treated by maxillectomy, and 2 were treated by debulking. At the time of follow-up at least 1 year after surgery, all 4 treated cats were alive, with owners reporting an acceptable quality of life.
Conclusions and Clinical Relevance—Osteoma of the oral and maxillofacial regions is an uncommon tumor in cats. Most cats are examined during an advanced stage of the disease, when treatment options may be limited. Although osteoma is a benign tumor, the recommendation is to perform a clinical evaluation, diagnostic imaging, biopsy, and treatment early in the disease process, when less invasive surgical approaches may be feasible.