pISSN 1598-298X
J Vet Clin 30(2) :127-130 (2013)
127
Clinical Effect of Guide Bone Regeneration of Mandibular Nonunion in a Geriatric Dog
Se-Eun Kim, Kyung-Mi Shim, Chun-Sik Bae, Seok-Hwa Choi*, Soon-Jeong Jeong** and Seong-Soo Kang1 College of Veterinary Medicine, Chonnam National University, Gwangju 500-757, Korea
*College of Veterinary Medicine, Chungbuk National University, Chungbuk 361-763, Korea
**School of Dentistry, Chosun University, Gwangju 501-759, Korea (Accepted: April 15, 2013)
Abstract : A 13-year-old, 4.2 kg female poodle was referred for failure of first bilateral mandibular surgery at a local animal hospital after pathologic fracture. Surgery was performed with 2.0-mm miniplates/screws and porcine cancellous bone grafts. In addition, because of the large size of the right segmental defect, a barrier absorbable membrane was employed for guide bone regeneration on right mandible. After surgery, follow-ups performed at 1 day, 1, 4, 8, and 12 weeks; there were no signs of dental malocclusion, nonunion or soft tissue infection. However, a 1-year long- term follow-up showed nonunion in the left mandibular fracture site for which a collagen membrane had not been used. It is considered that use of porcine bone graft with barrier absorbable membrane may be effective for the repair of mandibular nonunion in a geriatric dog.
Key words : nonunion, porcine cancellous bone, absorbable collagen membrane, mandibular fracture, dog.
Introduction
Fractures of the mandibular bodies are the most common oral fractures encountered by dogs (7). Most oral fractures are caused by automobile accidents, bite wound, and head trauma.
Mandibular fractures occur in the region of the canine tooth (9%), premolar (31%), molar (18%), symphysis (15%), and mandibular body (15%) (11).
The prognosis of mandibular fractures depends on many factors including the presence and absence of teeth, size of the soft tissue destruction, age, use of the dog, shape, local- ization and stability of the fracture, economic status of the owner, and the preference of the surgeons (3).
Many fixation techniques for mandibular fracture have been advocated by surgeons and include plate and screws, miniplates, interdental wires, intraoral splints, acrylic splints, external fixations, intramedullary pins, interfragmental or intra- osseous wires, interarcade wiring, dental composite applica- tion and tape muzzles, and combinations of these devices (9).
Each has advantages and disadvantages.
These fixation techniques, particularly bone plates and miniplates, need to provide stability so that the graft material spanning the mandibular defects can be incorporated success- fully for bone reconstitution (6). Historically, autogenous cancellous grafts have been considered the best method for filling bony defects (4). However, the limited availability of
autogenous cancellous bone (5) has prompted the develop- ment of other techniques to supplement or replace bone includ- ing cancellous allografts, xenografts, and alloplastic bone sub- stitutes. Allograft and xenograft bone substitutes can induce osteoinduction, osteoconduction, or both (1). Among the var- ious xenograft bone substitutes, porcine bone has been recently utilized in the bone healing procedure.
Porcine bone has a good osteoconductive property and it is remodeled and replaced by new bone over time. In this case, we report the clinical significance of the use of porcine can- cellous bone and barrier membrane by guided bone regener- ation (GBR) in a geriatric dog with segmental defects in the mandibular bodies as a result of non-healing mandibular fractures.
Case
A 13-year-old, 4.2 kg female poodle presented with non- union of the bilateral mandibular fractures. It is due to fail- ure of a bilateral mandibular surgery in a local hospital as treatment for pathologic fracture. The dog had suffered an inability to close its mouth and had saliva dripping from the mouth. The physical examination was normal except for bilat- eral mandibular fractures. Complete blood count and blood chemistry were within the normal reference ranges. Survey radiographs of the jaw revealed large defect fractures of the bilateral mandibular body (Figs 1 and 2). The problems were fibrous nonunions with large fracture gaps (left: 0.4 cm, right: 0.6 cm), potential for infection, and severe malocclu-
1Corresponding author.
E-mail: vetkang@chonnam.ac.kr
128 Se-Eun Kim, Kyung-Mi Shim, Chun-Sik Bae, Seok-Hwa Choi, Soon-Jeong Jeong and Seong-Soo Kang
sion. Thus, we considered definitive surgical correction and porcine cancellous bone grafts.
The dog was premedicated with cimetidine (H-2®AMP; 5 mg/kg, JW Pharmaceutical, Seoul, Korea), cefazoline (Cefa- zoline CKD INJ 1 g; 20 mg/kg, Chong Kun Dang Pharm, Seoul, Korea) by intravenous injection. Anesthesia was induced with medetomidine (Domitor; 48 ug/kg, Pfizer Animal Health Korea, Seoul, Korea), tiletamin/zolazepam (Zoletil®; 3 mg/
kg, Virbackorea, Seoul, Korea) and tramadol hydrochloride (Tramadol HCl Huons Inj.; 5.4 mg/kg, Huons Co., Gyeonggi, Korea) in the same syringe and maintained with isoflurane
(Forane® solution; JW Pharmaceutical, Seoul, Korea) and pure oxygen after tracheal intubation. The left and right man- dibular body defect fractures were brought into alignment and placed in normal occlusion using 2.0-mm titanium mini- plates/screws. The segmental defects in both mandibular bodies were spanned using porcine cancellous bone grafts. In addition, because of the large size of the right segmental defect, a barrier absorbable membrane (Lyoplant, B Braun, Tuttlingen, Germany) was employed for guide bone regener- ation (GBR) (Fig 3).
Occlusion was checked daily. Antibiotics and analgesics Fig 1. Radiographs taken before surgery. (A) Left, (B) Right.
Fig 2. Dental radiographs taken before surgery. (A) Left, (B) Right.
Fig 3. Photos of the surgical procedure. (A) Exposed mandibular fractures, (B) Placement in normal occlusion using 2.0-mm mini- plates/screws, (C) Porcine cancellous bone graft mixed with blood, (D) Application of absorbable guided bone regeneration membrane.
Clinical Effect of Guide Bone Regeneration of Mandibular Nonunion in a Geriatric Dog 129
were administered in the postoperative period. Meticulous oral hygiene was ensured with an oral rinse using 0.12%
chlorhexidine gluconate solution. In-hospital follow-up was performed at 1 day as well as at 1, 4, 8, 12 and 20 weeks.
The owner reported that the dog was eating and drinking nor- mally after surgery. All implants were stable at 4 and 8 weeks after surgery, and the radiographs performed at the 12 weeks follow-up examination showed that the graft site was undergoing continuous bone remodeling associated with frac- ture healing. And at 20 weeks, follow-up radiographs showed continuous bone healing (Fig 4) and no sign of dental maloc- clusion, nonunion, malunion, osteomyelitis or soft tissue in- fection. Eating, playing with toys, a rapid transition to solid food and a quick return to normal jaw movements were ob- served. However, a 1-year long-term follow-up showed non- union in left mandibular fracture site that had not involved use of collagen membrane (Fig 5).
Discussion
The goals of surgical repair of mandibular fractures are to achieve a stable rigid outcome at the fracture site, restore normal occlusion and preserve the blood supply to aid bone healing, avoid iatrogenic damage and facilitate an early return to normal function. Many repair techniques have been reported in the veterinary literature, including bone plating with con- ventional plates and miniplates, intramedullary pinning, exter- nal skeletal fixation, application of tape muzzles and inter- fragmentary wiring (9). No single technique is universally effective, especially where multiple fractures or segmental bone defects are present. In this case, we used several tech- niques (miniplate system, porcine cancellous bone grafts and membrane) to restore the function and cosmetic appearance
in the dog with nonunion of the bilateral mandibular fractures.
Reconstruction of the segmental mandibular defect is estab- lished using a bone graft substitute. In this case, the left and right mandibular body fractures were fixed with miniplates and screws. Grafting of porcine cancellous bone was per- formed on the bilateral fracture sites. The bone graft is able to fill the bone fracture site and provide a mechanical and biological scaffold that can be included in the tissue as bone remodeling occurs. Filling the bony defect with an autogenous graft is considered the best method of bone fracture healing.
Autogenous grafts are non-immunogenic and contain osteo- blasts and osteoprogenitor stem cells, which are capable of proliferation. Therefore, these grafts are osteoinductive. How- ever, there are limitations in obtaining autogenous grafts that include insufficient oral sites, requirement for a second surgi- cal site and morbidity at the donor site. All other forms of bone grafting have disadvantages compared with autogenous graft. However, technological evolution along with a better understanding of the bone-healing biology has led to the development of several bone graft substitutes including por- cine cancellous bone that are currently available to the ortho- paedic surgeons. In our previous study, we grafted porcine cancellous bone onto the bone defect site of rat calvarium. The outcomes were evaluated by visual appearance, radiographs, micro-computed tomography and histopathologic findings. As a result, we confirmed that porcine cancellous bone had good ability of bone regeneration and healing compared to β-tri- calcium phosphate (8). This time, we used porcine cancel- lous bone graft in bilateral mandibular bone fracture sites. In addition, the absorbable membrane (Lyoplant, B Braun; Tut- tlingen, Germany) was used for GBR in the right mandibu- lar fracture site because the bony defect was more serious than at the left mandibular fracture site. Both absorbable and Fig 4. Radiographs taken at 12 weeks after surgery. (A) Left, (B) Right.
Fig 5. Radiographs taken at one year after surgery. (A) Left, (B) Right.
130 Se-Eun Kim, Kyung-Mi Shim, Chun-Sik Bae, Seok-Hwa Choi, Soon-Jeong Jeong and Seong-Soo Kang
non-absorbable membrane can be used for the new bone regeneration. The membrane interrupts the soft tissue cells of the mucosa and promotes the generation of bone from the sur- rounding tissue to repopulate and regenerate the bony defects.
After surgery, radiographs of follow-up examination revealed that the graft regions of the bilateral mandibular fracture site had gradually healed up and fracture gaps were diminished until 20 weeks post-operation. However, a 1-year long-term follow-up showed bone graft absorption in the left mandibu- lar fracture gap. Thus, in this case, the right mandibular frac- ture healed well despite the fact that the right mandibular fracture gap was larger than the left mandibular fracture gap.
The principle of membrane GBR is well established in the treatment of bone defects and bone augmentation procedures (10). Collagen membranes of xenogene origin maintain their barrier function between 6 and 8 weeks, but also up to 4-6 months (2,12). Membrane GBR may be able to prevent nonos- teogenic soft tissue migration into the fracture site and obviate prolapse of bone substitutes in the bone defect. This suggests that the membrane used with porcine cancellous bone has a positive effect on bone regeneration for mandibular nonunion in a geriatric dog.
Acknowledgement
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2009-0073479).
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노령견의 하악골절 불유합 1례에서 골유도재생술의 임상적 효과
김세은·심경미·배춘식·최석화*·정순정**·강성수1
전남대학교 수의과대학, *충북대학교 수의과대학, **조선대학교 치과대학
요 약 : 13년령의 4.2 kg 암컷 푸들이 하악의 병적 골절 후 지역병원에서 받은 양측성 하악 수술의 실패로 내원하였 다. 수술은 2.0-mm miniplates/screws, 돼지해면질골 및 흡수성 막을 사용해 시행되었다. 수술 후 1일, 1, 4, 8, 12주 에 예후를 평가하였다; 치아 부정교합, 골절 불유합, 또는 연부조직 감염의 징후는 보이지 않았다. 그러나 1년 후 장 기간 검진에서 콜라겐 막을 사용하지 않았던 왼쪽 하악골절부위에 불유합이 관찰되었다. 따라서 노령견에서 하악골 불 유합의 치유에 돼지해면골과 흡수성 막을 함께 사용하는 것은 효과적이라 생각된다.
주요어 : 불유합, 돼지해면질골, 흡수성 콜라겐 막, 하악골절, 개
