Tunable activation of therapeutic platelet-rich plasma by pulse electric field: Differential effects on clot formation, growth factor release, and platelet morphology.

BACKGROUND: Activation of platelet-rich plasma (PRP) by pulse electric field (PEF) releases growth factors which promote wound healing (e.g., PDGF, VEGF for granulation, EGF for epithelialization). AIMS: To determine after PEF activation of therapeutic PRP: 1) platelet gel strength; 2) profile of released growth factors; 3) alpha- and T-granule release; 4) platelet morphology. METHODS: Concentrated normal donor PRP was activated by 5 µsec (long) monopolar pulse, ~4000 V/cm (PEF A) or 150 nsec (short) bipolar pulse, ~3000 V/cm (PEF B) in the presence of 2.5 mM (low) or 20 mM (high) added CaCl2. Clot formation was evaluated by thromboelastography (TEG). Surface exposure of alpha granule (P-selectin) and T-granule (TLR9 and protein disulfide isomerase [PDI]) markers were assessed by flow cytometry. Factors in supernatants of activated PRP were measured by ELISA. Platelet morphology was evaluated by transmission electron microscopy (TEM). RESULTS: Time to initial clot formation was shorter with thrombin (<1 min) than with PEF A and B (4.4-8.7 min) but clot strength (elastic modulus, derived from TEG maximum amplitude) was greater with PEF B than with either thrombin or PEF A (p<0.05). Supernatants of PRP activated with PEF A had higher EGF levels than supernatants from all other conditions. In contrast, levels of PF4, PDGF, and VEGF in supernatants were not significantly different after PEF A, PEF B, and thrombin activation. T-granule markers (TLR9 and PDI) were higher after thrombin than after PEF A or B with low or high CaCl2. By TEM, platelets in PEF-treated samples retained a subset of granules suggesting regulated granule release. CONCLUSION: Pulse length and polarity can be modulated to produce therapeutic platelet gels as strong or stronger than those produced by thrombin, and this is tunable to produce growth factor profiles enhanced in specific factors important for different stages of wound healing.

Feline Dental Implants: Long-Term Follow-up of Two Cases.

Dental implants have become an option for replacement of lost canine teeth in cats. Although cats appear to manage well after a canine extraction, complications such as lip entrapment can occur after maxillary canine tooth extraction. Even cats with a complicated crown fracture of the maxillary canine tooth that have had root canal therapy can develop lip entrapment. This can lead to painful lip ulcers and potential need for further dental treatment. Canine tooth replacement with a dental implant and prosthodontic crown is, in the authors' experience, a predictable option that can be offered to clients who would like to replace a lost canine tooth. This report will discuss 2 long-term cases of maxillary canines replaced by dental implants/crowns.

Dental Implants and Incisor Bridge Placement in a Dog.

Veterinary dentistry has tended to follow the trends and advancements in the human dental field. As for any procedure performed on a patient, whether human or animal, an informed decision is based on the available evidence regarding treatment options. This is certainly true for the more involved treatments in veterinary dentistry which can include the disciplines of endodontics and dental implantology. A number of published case reports have been accepted by the specialty that endodontic therapy is indeed a predictable and a valuable service that can be offered to pet owners. Oral implantology has become an accepted and predictable procedure in the human dental field and can now be offered to pet owners if performed by suitable trained veterinary clinicians. The success rate for endosseous implant osseointegration is very high in humans. Success rates are also very high in animals used for implantology research. Canine studies have shown good bone-to-implant contact of around 73% in osseointegrated endosseous implants based on histological sections. Radiographic and histological findings demonstrate stable alveolar crestal bone levels after loading endosseous implants for up to 12 months in a dog model. This article discusses use of dental implants in the rostral mandible of a companion dog to replace periodontally diseased incisors, their restoration, to return the animal to full dental function and 3-year follow-up.

Oral examination in the cat: a systematic approach.

PRACTICAL RELEVANCE: Oral examination in the cat is a process of observing both normal and abnormal, and should be an integral part of any wellness examination as well as a response to any specific complaint(s). The basis for an accurate diagnosis is meticulous attention to detail. It is essential that the clinician performs a whole body examination prior to examining the head and neck region. STAGES OF EXAMINATION: A thorough oral examination involves four stages. The first stage is to review the current oral problem(s) by asking questions and listening carefully to the owner's responses; gaining a thorough medical/dental history may shed more light on the current problem(s). The second stage is an extraoral physical examination to visualise and palpate the head and neck regions in the awake patient. In the third stage the clinician performs an intraoral examination in the awake patient, before proceeding to the final stage, which is an extraoral and intraoral examination under general anaesthesia. AIM: This article describes a systematic approach to the oral examination, based on these four stages. The aim of this process is not only to facilitate the making and recording of observations, but also to help avoid missing important clues that may aid in reaching a diagnosis. Common tooth pathologies in the feline patient are also briefly reviewed, paving the way for accompanying articles in this two-part Special Issue, which will provide further insight into these pathologies and discuss management approaches.

Transmucosal healing around peri-implant defects: crestal and subcrestal implant placement in dogs.

OBJECTIVE: This study was designed to evaluate the transmucosal healing response of implants placed with the junction of the smooth surfaces, either crestal or subcrestal, into simulated extraction defects after healing periods of 1 and 3 months. MATERIALS AND METHODS: A total of 23 Straumann SP v3.3 mm NN, SLA 10 mm implants were placed in the mandibular premolar regions of three greyhound dogs 3 months after the teeth were removed. Five control implants were placed at the crestal bone level, and test implants with surgically created peri-implant defects of 1.25 mm wide x 5 mm depth were placed either at the crestal (nine implants) or at the 2 mm subcrestal (nine implants) bone level. Implants on the right side were placed 1 month before the dogs were sacrificed, and implants on the left side were placed 3 months before sacrifice. All dogs had daily plaque control following surgery and were sacrificed 3 months after implant placement for histological and histometric analyses. RESULTS: Mesial-distal ground sections of the control and test implant specimens showed a greater %BIC in the coronal defect region after 3 months of healing. This healing response was incomplete for the test implants compared with the control implants after a 1-month healing period. The histometric measurements for test implants placed at the crestal bone level or 2 mm subcrestal with surgically created peri-implant defects were more coronal or closer to the implant margin compared with the control implants. Additionally, the degree of osseointegration between the newly formed bone and the implant surface was similar between the test implants. CONCLUSION: Peri-implant defects of 1.25 mm width healed with spontaneous bone regeneration around implants placed transmucosally at crestal or 2 mm subcrestal with a high degree of osseointegration after a 3-month healing period.

Fibrous dysplasia of mandibular bone in a dog.

A nine-year-old, male German shepherd dog was presented with a firm, discrete mass lingual to the interdental space of the mandibular left third and fourth premolars. The lesion was excised and diagnosed as fibrous dysplasia of bone based on histopathologic examination. Fibrous dysplasia of bone is a rare, non-aggressive, radiolucent, non-neoplastic lesion considered developmental in origin. Usually observed as a solitary lesion, it has been reported in animals and man in the polyostotic form. The disease process causes deformity of bone which may lead to loss of bone strength. Clinical signs are secondary to site specific problems associated with expansile bone lesions. Oral examination performed 18-months postoperatively indicated no signs of recurrence.