Free mucosal grafts in miniature swine and man

Tissue adhesive in free gingival graft

The aim of the present study was to review the literature regarding the utilization of 2-octyl cyanoacrylate's (Dermabond®, Ethicon US, USA) as a tissue adhesive in dentistry; also, to report its use in the stabilization and fixation of a free gingival graft, indicated to increase the width of the keratinized attached mucosa at the lower incisive region. Literature analysis revealed numerous indications for this tissue adhesive in the medical field related to maxillofacial injuries. In dentistry, clinical reports, as well as controlled clinical studies conducted in humans and in animal models, using histological analysis described positive results for the use of different cyanoacrylate-based tissue adhesives. These studies reported that the use of tissue adhesives reduced the surgical procedure time period, eliminated postoperative visits as well as the discomfort of suture removal and, in addition, did not interfere with the clinical repair process. Favorable results, like the ones described in the literature, were obtained in the present case report using Dermabond®.

Evaluation of the effects of diagnostic radiation on titanium dental implant osseointegration in the micropig

The effect that diagnostic radiation may have on peri-implant supporting alveolar tissues is not well understood. Fifty-four (54) titanium dental implants were inserted into the posterior mandible of nine micropigs. At implant placement surgery, 18 implants were exposed to either 2 (diagnostic) or 10 (excessive) doses of diagnostic radiation; the remaining 36 implants served as controls. Fourteen weeks after implant placement, standardized clinical radiographs were taken, pigs were euthanized, and implants with supporting alveolar tissues were prepared and examined by light and scanning electron microscopy (SEM). Ninety-seven sections were evaluated by SEM for morphometric and morphologic analyses. The mean percent of implant length in contact with bone was 47% for the controls and 53% for the implants receiving radiation. Five implants were lost during the initial healing phase and four implants were clinically mobile at time of euthanasia, giving a success rate of 83% (45/54). Correlative light microscopy of peri-implant supporting tissues revealed no distinct differences between the microvasculature of controls versus implants exposed to radiation. Standardized clinical radiographs revealed crestal saucerization in both control and radiated implants. This study revealed no statistically significant difference for the percent of implant length in contact with alveolar bone for controls or implants exposed to 2 or 10 doses of diagnostic radiation at implant placement time.

Development of chronic mandibular osteomyelitis in a miniswine model

Previous attempts to develop a reproducible model of chronic mandibular osteomyelitis have met with limited success. In this study, osteomyelitis was produced in the mandibles of eight adult Yucatan miniswine by the intramedullary application of sodium morrhuate, Staphylococcus aureus, and either polymethylmethacrylate bone cement or bone wax. At 8 weeks' postinfection, the mandibles were surgically debrided and specimens were obtained for culture. Although all of the animals developed clinical evidence of osteomyelitis that was supported by positive cultures, the original organism (S aureus) was recovered only from those animals where bone wax had been used to seal the cortical defects. This animal model may be useful for evaluating newer treatment modalities for chronic osteomyelitis.

Surgical treatment of induced peri-implantitis in the micro pig: clinical and histological analysis

The purpose of this pilot study was to determine if lost osseous support adjacent to root form implants could be regenerated using a guided tissue regeneration technique. Three fixtures were placed in each edentulous mandibular bicuspid region of two micro pigs. A total of 6 fixtures were placed in each pig. Due to the presence of a pathologic condition, which was in no way related to the research, the results of one pig were not evaluated. Following osseointegration, peri-implantitis were induced by the use of ligatures and a soft diet. Three modalities of treatment were performed. Utilizing a surgical flap approach, one third of the fixtures (one per quadrant) were covered with expanded polytetrafluoroethylene (ePTFE) membrane and submerged under the soft tissue complex. The second group of fixtures were submerged under the soft tissue complex with no ePTFE membrane. The control fixtures along with their abutments were debrided and remained non-submerged. All fixtures were debrided using an air-abrasive polishing system. The osseous defects around the fixtures were measured from a fixed reference point at the time of surgery and after obtaining block sections.(ABSTRACT TRUNCATED AT 250 WORDS)

Microbiologic characterization of ligature-induced peri-implantitis in the microswine model

The purpose of this study was to evaluate the microbiologic changes associated with induction of peri-implantitis in the microswine. A split-mouth design was utilized. Three implants were placed in the edentulous mandibular bicuspid region of 2 microswine yielding 12 implants for evaluation. The experimental implant abutments were ligated with 4-0 silk suture material to induce peri-implantitis for a period of 45 days. The control implant abutments were not ligated. The control implants were scaled and cleaned at each time interval using plastic scalers. The attachment level (AL), probing depth (PD), gingival index (GI), and plaque index (PI) were measured at day 0 (baseline) and days 14 and 45. Microbiologic samples were taken from the "sulcus" with paper points at each interval and were dispersed in prereduced media; plated on selective and non-selective media; and grown under aerobic, anaerobic, and capnophilic atmospheres. A greater AL, increased PD, and higher GI and PI scores were noted among the experimental implants. The controls remained essentially unchanged. Radiographs revealed that experimental implants showed an increased amount of bone loss when compared to control. Bone loss caused the implant threads to be exposed in the experimental implants. Microbiologic studies revealed that there was a shift from Gram-positive facultative organisms to Gram-negative obligate anaerobes, including black pigmented Bacteroides, in experimental implants. The microbiota of the control implants remained primarily Gram-positive facultative organisms. The microswine appears to be a suitable animal model for evaluation of osseointegrated implants. Importantly, under the experimental conditions reported, osseointegrated implants were susceptible to "periodontal" breakdown or peri-implantitis.

A comparative biochemical and immunological analysis of cytokeratin patterns in the oral epithelium of the miniature pig and man

In man, cytokeratin constitutes a family of 19 polypeptides that show different but distinct distribution patterns in the various epithelia. Changes in these patterns may occur during epithelial development and differentiation. The cytokeratin patterns in the oral mucosa of the miniature pig, an animal used in studies of wound healing, were investigated. Surgical biopsies were obtained from the gingiva, hard palate and alveolar mucosa of both man and pig. The cytokeratins were analysed by immunofluorescence, two-dimensional gel electrophoresis and by immunoblotting. Nine monoclonal antibodies were used to identify the different cytokeratin polypeptides in cryostat sections. Two-dimensional gel electrophoresis showed that pig oral mucosa contains at least 10 different polypeptides, five of the acidic type I and five of the basic type II cytokeratins. These were different from the human cytokeratin polypeptides and accordingly were designated P1-P10, according to their molecular weight and isoelectric mobility. Their molecular weight varied between 48 and 69 kdalton and the pHi varied between 5 and 7.3. Immunoblotting showed the monoclonal antibody Ks 13.1 (anticytokeratins Nos 13 and 14) to cross-react with the pig polypeptides P10 and P8. Immunolocalization showed that all the antibodies cross-reacted with the pig tissue except Ks 19.1 (anticytokeratin No. 19). It was possible to differentiate between pig alveolar mucosa, which expressed only P3, P4, P5, P8 and P10, and the gingival and hard palatal mucosae, which expressed all 10 polypeptides except P5. This distinction was made by antibody 6B10 (anticytokeratin No. 4), which reacted only with alveolar mucosa; antibody Ks 13.1, which strongly reacted with uncornified mucosa but weakly with cornified mucosa (gingiva and palate); and any of RKSE60, Kk 8.60 or EE21.6 (anticytokeratin No. 10, anticytokeratins Nos 10 and 11 and anticytokeratins Nos 1, 2, 10 and 11, respectively), which reacted strongly with cornified mucosa but weakly, if at all, with uncornified mucosa. These findings provide a baseline for studies on epithelial differentiation in the miniature pig such as in wound healing.

Chronic mucogingival defects in miniature swine

Controversy surrounds the importance of keratinized gingiva in maintaining periodontal health. A well-defined animal model system is necessary to evaluate longitudinally the role of keratinized gingiva when plaque control is inadequate or where dental procedures (restorative, prosthetic or orthodontic) alter the periodontal environment. Facial gingiva was excised from eight primary incisors in miniature swine. Contralateral teeth were used as controls. The experimental teeth exhibited mucogingival defects at 3 and 6 month observation periods. The secondary teeth erupting into the experimental regions also exhibited recession and chronic mucogingival defects. The marginal tissue in regions devoid of keratinized gingiva demonstrated clinical signs of inflammation. No progressive gingival recession was present. Excision of keratinized gingiva to produce mucogingival defects in swine provides a convenient model system for evaluating the effect of dental procedures on periodontal health where little or no keratinized gingiva is present.

The sutureless free gingival graft

A technique designed to utilize the autogenous free gingival graft without the use of sutures was demonstrated. Necessary objectives were maintained but achieved without unnecessarily piercing the graft, and in less time. The only variance in results would be due to the underlying physical properties of the recipient site. This new approach to grafting avoids the cyanoacrylate from getting between the graft and recipient site, therefore acting as a foreign body. Also shown was the complete coverage of a denuded root surface by this technique using a free autogenous gingival graft. This technique enables the surgeon to achieve the results of a predictable technique (autogenous free gingival graft) even more predictably simple.

Placement of free gingival grafts on denuded alveolar bone. Part I: clinical evaluations

Fourteen patients were examined and determined to lack an adequate zone of attached gingiva in the mandibular incisor region. Each patient was treated on the left side of the mandible by placement of a free gingival graft on denuded bone and 12 of the 14 patients received a free gingival graft on retained periosteum in the right mandibular anterior region. Two patients were treated on the right side by either bone denudation or periosteal bed preparation without graft placement to permit histological evaluation of wound healing under these circumstances. Grafts were retained for time intervals from 1 week to 24 weeks. All patients were evaluated clinically for graft "take", graft healing, graft shrinkage, and graft mobility.

Complications of free grafts of masticatory mucosa

A discussion has been presented and examples provided to illustrate some of the complications that may be encountered in conjunction with free grafts of masticatory mucosa. The clinical problems presented are seen infrequently, but the clinician must be aware of the possibility of their occurrence when counseling patients on the possible sequelae of such surgical procedures. A knowledge of complications that may occur in free soft tissue grafting procedures, and of the underlying mechanisms causing these problems, may aid the clinician in anticipating and avoiding similar experiences.