Histologic and clinical study of mucosal (gingival) transplants in dogs

Influence of freeze-dried bone allograft on free gingival graft survival and alveolar ridge maintenance in socket seal procedures: a randomized controlled clinical trial

PURPOSE

This study aimed to investigate the viability of free gingival grafts (FGG) and assess clinical and radiographic changes in the alveolar ridge following socket seal surgery with or without freeze-dried bone allograft (FDBA).

MATERIALS AND METHODS

Twenty-eight anterior and premolar tooth extractions were randomly allocated to 2 groups: socket graft of FDBA sealed with FGG (n = 15) and control with empty sockets sealed solely with FGG (n = 13). Photographs taken at 3, 7, 14, and 30 days post-surgery assessed FGG viability. Alveolar ridge volume was clinically evaluated via intraoral scanners before surgery and at 1 and 3 months post-surgery. CBCT scans taken immediately post-surgery and 3 months later assessed alveolar ridge dimensions.

RESULTS

FGG viability in both groups increased from day 3 and reached the maximum score on day 14. Alveolar ridge volume reduction at 3 months in the FDBA group was comparable to the control group. Buccal alveolar bone height reduction was significantly higher in the FDBA group than the control group, while palatal alveolar bone height was comparable. Alveolar bone width reduction was evident but not statistically significant between the groups. The FDBA group exhibited a significant alteration in bone volume compared to the control group.

CONCLUSION

Viability of FGG was not affected by graft filling materials. Sealing the socket with FGG effectively preserved socket integrity and ridge volume in minor socket defects using either graft filling material or not. This study was registered on 4 January 2021 on Thai Clinical Trials Registry (TCTR20210104001).

Soft Tissue Regeneration at Natural Teeth

This article provides an overview of the best-documented surgical techniques for recession coverage and draws conclusions for the clinician. Use of a connective tissue graft with either coronally advanced flap (CAF) or tunnel is the most predictable technique for the treatment of single and multiple gingival recessions. Long-term results exist only for CAF with/without connective tissue graft providing evidence for long-term stability with only minor relapses. Soft tissue replacement materials and biologics may represent a valuable modality to additionally improve the clinical outcomes obtained with CAF alone or, in certain clinical situations, to serve as an alternative to autogenous tissue.

Fibrin adhesive derived from snake venom in periodontal surgery: histological analysis

BACKGROUND

A new fibrin adhesive made of buffalo plasma-derived fibrinogen and a thrombin-like snake venom enzyme, has been successfully used to immobilize free gingival grafts. This case series histologically compared sutured grafts (control group) with others immobilized by using the fibrin adhesive (experimental group).

CASE DESCRIPTION

The grafts were placed in the contralateral mandibular bicuspids of 15 patients, so that each subject received one treatment of each type. Five biopsies of each group were collected at 7, 14 and 45 days of healing, which were histologically and morphometrically analyzed as regards the relative volume density of the different connective tissue components.

RESULTS

The sites in the control group presented a higher inflammatory cell density at 7 days and a tendency towards a lower collagen density. In the experimental group, the grafts had an appearance of more advanced healing. Tissue maturity characteristics progressed until 14 and 45 days, but no difference between groups could be noted at these times.

CONCLUSIONS

Within the limits of the present study, it may be suggested that the alternative fibrin adhesive tested could represent an alternative to sutures in gingival grafts procedures.

A critical evaluation of methods for root coverage

Gingival recession is the exposure of root surfaces due to apical migration of the gingival tissue margins. Although it seldom results in tooth loss, marginal tissue recession is associated with thermal and tactile sensitivity, esthetic complaints, and a tendency toward root caries. This article reviews the current surgical procedures for the coverage of exposed root surfaces, including their advantages and disadvantages. Today, the outcome of root coverage procedures is predictable, aesthetically acceptable, and, together with the use of guided tissue regeneration, at the forefront of regenerative procedures.

Ultrastructural changes of subepithelial capillaries following graft epithelialization

This study investigated architectural changes in the nourishment-providing capillaries beneath the epithelium that accompany graft epithelialization. A total of 77 mongrel dogs underwent free gingival autografts involving the maxillary canine and its attached gingiva. Comparative investigations relating the architectural transformations and endothelial permeability of the capillaries were made histopathologically, with graft epithelialization as an indicator. Microscopic findings revealed that the subepithelial capillaries transformed from loop structure into glomus-like structures. The endothelium changed ultrastructurally from the continuous type to the fenestrated. This occurred during the most active graft epithelialization phase. By the time the epithelium of the graft had matured, the fenestrated microvascular structure reverted to the continuous type and changed from a glomus-like structure to a network capillary system. However, by the 84th postoperative day, the subepithelial capillaries, still exhibiting network structure, had not yet returned to the loop structure indigenous to the gingiva. Observations indicated that transformation of the structure of the nourishment-providing capillaries was attendant to and simultaneous with the changes brought about by graft epithelialization.

The healing of hamster oral mucosal wounds covered by porcine grafts. A histologic study

The purpose of this study was to ascertain whether porcine skin grafts are incorporated by the host or act as temporary dressings which are sloughed and to determine the host reaction in terms of inflammatory response. A split-thickness 5-mm square recipient bed was prepared in the cheek pouches of 20 hamsters. Previously frozen, irradiated porcine skin was sutured onto each bed. Animals were killed at 3, 7, 10, 14 and 28 days. Results indicated that at 3 days the graft showed signs of necrosis and host epithelium was migrating under it. Some acute inflammation was evident. By 7 days all 7 grafts had sloughed and epithelialization was complete. The graft bed was maturing collagenous tissue with a mild infiltrate of chronic inflammatory cells. At 10 days healing was almost complete. In all instances the graft appeared to have been sloughed between the 3rd and 7th day and there was no evidence of a massive inflammatory response, foreign body reaction, host incorporation or graft vascularization. These results suggest that porcine skin could be used as a "biologic dressing" in periodontal mucogingival surgery involving grafting.

Role of attached gingiva for maintenance of periodontal health. Healing following excisional and grafting procedures in dogs

The present study was undertaken to analyze the role of attached gingiva for the maintenance of periodontal health in sites with normal and reduced height of the supporting apparatus. Furthermore, the effect of excision and grafting of gingiva on some parameters describing dimensions and location of the periodontal tissues was evaluated. 7 beagle dogs were used. A baseline examination comprised assessments of dental plaque, gingival conditions, attachment level, position of the gingival margin and width of the keratinized and the attached gingiva. In the right side of the jaws (experimental side) a 6-month period of periodontal tissue breakdown was followed by surgical excision of the entire zone of the gingiva. After another 4-month period of healing with daily plaque control, a gingival graft was inserted in one quadrant of the experimental side to regain a zone of attached gingiva while the other quadrant of the experimental side was left ungrafted. In the left side of the jaws (control side), the teeth were subjected to daily meticulous plaque control during the entire study. In one of the control quadrants the entire zone of the keratinized and attached gingiva was excised at a time point corresponding to the grafting procedure in the experimental side, while the gingiva in the remaining control jaw quadrant was left unoperated. Clinical examinations of all control and experimental tooth units were repeated at certain time intervals during the course of the study. The final examination was carried out 4 months after grafting. The results of the experiment showed that in sites exposed to careful plaque control measures gingival health could be established and maintained without sign of recession of the gingival margin or loss of attachment, independent of (1) presence or absence of attached gingiva, (2) width of keratinized gingiva or (3) height of the supporting attachment apparatus. Following surgical excision of the entire gingiva, all buccal sites regained a zone of keratinized gingiva, but most sites were lacking attached gingiva. Furthermore, grafting of gingival tissue significantly increased the width of the keratinized and the attached gingiva but had no obvious effect on the position of the gingival margin or the level of the attachment.

Preprosthetic mandibular vestibuloplasty with buccal mucosal graft. A 2-year follow-up study

21 patients with denture retention problems due to lack of mandibular vestibular denture space and alveolar ridge atrophy had a vestibuloplasty with free grafting of check mucosa performed under local anaesthesia on an out-patient basis. Follow-up examinations based on metric records showed that 18% of the sulcus extension is lost during the first post-operative month, but regained by the time of the 6-month control, leaving 99% of the surgically created sulcus extension as a permanent gain. The grafted check mucosa served well as a denture-bearing tissue, and almost all patient had a significant improvement of denture retention and stability. Complications were few. The biology of healing is discussed in the light of recent concepts of wound healing.

Experimental study on the free transplantation of mucosa and lyophilised dura to the oral cavity

The covering of epithelial defects in the oral cavity presents special problems in preprosthetic surgery, since special requisites for function and quality of mucosal grafts must be satisfied. In animal experiments mucosal defects in the oral cavity of 30 rabbits were repaired with free transplants of autologous mucosa and heterologous lyophilised dura. A comparative clinical and histological assessment of the healing processes showed that there was no essential difference between both methods. Considering the necessary second intervention, the infliction of a second wound, as well as the limited source of mucosa, our results show that the use of lyophilised dura in preprosthetic surgery is preferable.

A scanning electron microscopic study of the healing of free gingival grafts

1. Gingiva from the buccal surfaces of the mandibular first molars was grafted to the alveolar mucosa of each of the three premolars in six adult Beagle dogs. Biopsies were made at 0,2,3,4,5,6,7,8,10,14,21 days and at 1 and 6 months. 2. The specimens were fixed in 2% glutaraldehyde, buffered with cacodylate, pH 7.4, rinsed in buffer, dehydrated in graded alcohols, critical point dried, coated with gold palladium alloy and viewed in an AMR-1000 SEM at a tilt of 20 to 25 degrees and an accelerating voltage of 20 kv. 3. The results of this study parallel those reported on the basis of light microscopic studies. The three-dimensional visualization of the graft shows that the external layer of epithelium degenerates and desquamates, except for the basal layer and the structural architecture of the connective tissue is not as well organized. 4. By 21 days the graft is essentially healed, both clinically and histologically.

Clinical evaluation of free autogenous gengival grafts placed on alveolar bone. Part I. Clinical predictability

1. Thirty free autogenous gingival grafts were placed on bone and 30 were placed on a periosteal bed. The distribution into the groups was random. All 60 grafts survived, showing that both procedures were predictable. 2. Over one-half (17 of 30) of those on periosteum demonstrated mobility by 6 months postoperatively. No mobility was observed in the group placed directly on bone. 3. Osseous placed grafts demonstrated less swelling and better hemostasis than did the periosteally placed grafts. 4. A healing lag was observed in the grafts placed on bone which lasted only for the first two postoperative visits, approximately 2 weeks. 5. No infections or sequestrations were noted in any case.

Retardation of epithelial migration in new attachment attempts in intrabony defects in monkeys

New attachment procedures were performed in 80 three-wall intrabony defects produced adjacent to incisors and canines in monkeys. Following a reverse bevel incision, mucoperiosteal flaps were raised on the buccal and lingual aspect of 40 intrabony defects. All soft tissue was removed from the defects and following transplantation of autogenous bone grafts, the tissue flaps were replaced and sutured. On the buccal and lingual aspect of another 40 intrabony defects a split flap procedure was performed. Granulation tissue was removed from the defects and following transplantation of autogenous bone grafts, the defects were covered with free palatal grafts. The animals were sacrificed to yield observation periods from 0 to 42 days. After decalcification of the specimens and embedding in paraffin, 8-mum serial sections were cut and stained. The epithelium on the full thickness flap seemed almost unaffected by the surgical procedure and had migrated between 0.2 mm and 2.0 mm along the root surface during the first week of healing. The epithelium on the transplants degenerated almost completely within the first week after surgery and epithelial migration along the root surface was not observed until after 10-12 days. These results indicate that the migration of epithelium during the postoperative phase of new attachment attempts can be retarded by covering the defects with free palatal grafts instead of full thickness flaps.

Fluorescein angiography of free gingival autografts

The capillary blood circulation of free gingival autografts during healing was studied by means of 45 fluorescein angiographs taken over a postoperative period of 14 days in 10 female patients, 21 to 36 years old. The surgical technique commonly used for transplanting gingiva was slightly modified in that no surgical dressings and, in 3 cases, not even sutures were employed to immobilize the grafts. During the first 3 postoperative days, fluorescent plasmatic diffusion of increasing intensity was observed. In one case, fluorescing capillary circulation was detected as early as 24 hours after surgery, fluorescent capillaries became evident in all graft sites and increased steadily in number. Between 9 and 14 days after surgery, an even capillary loop pattern was established.

Clinical comparison of the free soft tissue autograft and partial thickness apically positioned flap--preoperative gingival or mucosal margins

Apically positioned split thickness flaps were performed at two selected sites in each of 10 patients. Equivalent amounts of periosteum were left exposed to standardize the method. In five patients the preoperative dentogingival margins consisted of gingiva, whereas in the five others a margin of alveolar mucosa was present. In all patients the pre-existing margin was sutured apically to periosteum, after reflection of the split thickness flap. At one surgical site in each patient a free soft tissue autograft, donated from the palate, was sutured to the periosteum left exposed coronal to the apically positioned flap margin. The second surgical site was left not covered by any biological dressing. Measurements from three fixed reference points on a stable acrylic device were recorded preoperatively and at 2, 4, 6, 8 and 12 weeks postoperatively. The graft and split thickness flap procedures were then biometrically compared by application of the Null Hypothesis and t test for the difference of the means to determine any significant differences. It was concluded that the presence of a preoperative dentogingival margin of gingiva suggested that either the free graft or split flap procedure would eliminate pockets extending beyond the mucogingival junction, and would establish adequate zones of attached gingiva without deformity at the dentogingival junction. However, the presence of a preoperative margin of alveolar mucosa suggested the use of the free soft tissue autograft to attain the above. The thickness of connective tissue afforded by a preoperative margin of gingiva was assumed to be the responsible factor for the above conclusions.