Experimental assessment of histological and biological properties of the induced membrane and the membrane formed around the d-PTFE membrane: A pilot study.

BACKGROUND: The aim of this prospective pilot study is to find answers to the following question: In the treatment protocol of open membrane technique defined by Funakoshi, do the histological and biological properties of the tissue that has already covered the graft surface following the removal of the d-PTFE membrane resemble those properties of induced membrane? MATERIAL AND METHODS: 4 male, white Vienna rabbits were used for experiments. Bicortical and 10mm in diameter four bone defects were created on each calvarial bone. 2 rabbits (8 defects) were accepted as group I and other 2 rabbits (8 defects) were accepted as group II. Bone cement was placed into the all-defect in group I. 8 defects were filled with Bi-Oss graft material and covered with d-PTFE membranes in group II. After 8 weeks, sacrifice of the rabbits was performed. In group I, without damaging the formed membrane around it, the bone cement was removed from the defects and the achieved membrane was sent to the pathology department. In group II, the thin film layer that formed under the d-PTFE membrane was sent for histological evaluations. Inflammation, edema, foreign body reaction, synovial-like epithelium existence, thickness, vascularisation (CD31, VEGF), fibrosis were assessed. RESULTS: Inflammation, fibrosis and thickness measurements are significantly different between the groups (P<0,05) and for these parameters, the mean of d-PTFE group (Group II) is significantly higher than the mean of the induced-membrane group (Group I). There isn't any significant difference for other parameters. CONCLUSION: The morphological characteristics of membranes of the two groups were similar. There was a cell-rich, vascularised tissue with fibrous structures; fibroblasts, myofibroblast, and collagen, orientated parallel to the cement.

The effects of ozone application on genotoxic damage and wound healing in bisphosphonate-applied human gingival fibroblast cells.

OBJECTIVES: Medication-related osteonecrosis of the jaws (MRONJ) is an extremely therapy-resistant disease involving the jaws especially following bisphosphonate treatment. Bisphosphonates accumulate in bone in concentrations sufficient to be directly toxic to the oral epithelium. Current therapeutic options are inadequate for the prevention and treatment of MRONJ. The aim of this study was to investigate effects of ozone gas plasma therapy on wound healing in bisphosphonate-applied human fibroblasts. MATERIAL AND METHODS: Human primary gingival fibroblasts were cultured. Cytotoxic concentrations (IC50) of bisphosphonates (pamidronate (PAM), alendronate (ALN), and zoledronate (ZOL)) were determined by MTT test. A 60 µg/µl for 30 s of ozone gas plasma application was performed to all experimental culture flasks after drug treatment at 24-h intervals as 3 s/cm2. Genotoxic damages were evaluated by comet assay and wound healing was determined by in vitro scratch assay. RESULTS: PAM, ALN, and ZOL applications caused genotoxic damage on primary human gingival fibroblast DNA. Ozone gas plasma therapy significantly decreased the genotoxic damage (p < 0.05), and this application provided 25, 29, and 27% less genotoxic damage in order of ALN, PAM, and ZOL groups. Ozone gas plasma therapy significantly increased wound healing rates both in postsurgical 24th and 48th hours for all doses of experimental drug groups (p < 0.05). CONCLUSION: The ozone gas plasma application decreased genotoxic damage effect of bisphosphonate usage while improved the wound closure rate on human gingival fibroblasts. CLINICAL RELEVANCE: Ozone gas plasma therapy may be helpful in prevention of gingival healing delay in MRONJ pathogenesis especially when applied simultaneously with surgical intervention.

Effects of alendronate and pamidronate on apoptosis and cell proliferation in cultured primary human gingival fibroblasts.

Data arising from the recent literature directed the researchers to study on the degree and extent of bisphosphonate toxicity on oral mucosa in further detail. The aim of this study is to determine the half maximal inhibitory concentration of pamidronate (PAM) and alendronate (ALN) on human gingival fibroblasts in vitro using 3-[4.5-thiazol-2-yl]-2.5-diphenyltetrazolium bromide (MTT) assay and to evaluate the effects of both agents on the proliferation and apoptotic indices. Cells used in the study were generated from human gingival specimens and divided into alendronate (n = 240), PAM (n = 240), and control groups (n = 60). Based on the MTT assay results, 10(-4), 10(-5), 10(-6), and 10(-7) M concentrations of both drugs were administered and the effects were evaluated for 6, 12, 24, 48, or 72 h periods. An indirect immunofluorescence technique was used to evaluate apoptotic (anti-caspase 3) and proliferation (anti-Ki67) indices. Toxicity of both PAM and ALN was found to be the most potent at 10(-4)-10(-5) M range. The apoptotic index of PAM group was found to be significantly higher than ALN group for all concentrations especially at 24 h incubation time (p < 0.05). The decrease in the proliferation index was found similar in first 48 h for both drugs; however, after 72 h of incubation decrease in proliferation index in PAM group was found to be significantly higher (p < 0.05). Micromolar concentrations of not only PAM but also ALN rapidly affect cells generated from human oral gingival tissue by inducing apoptosis together with inhibition of proliferation. Cytotoxic effects of both ALN and PAM on primary human gingival fibroblasts, which cause significant changes in apoptotic and proliferative indices as shown in this in vitro study, suggests that the defective epithelialization of oral mucosa is possibly a major factor on the onset of bisphosphonate-related osteonecrosis of the jaw cases.

The effect of cola consumption on oral mucosa in rats.

Drinks that contain phosphoric acid have been shown to have erosive effects and cola drinks are strongly acidic (pH 2.5). Gingivitis may be caused by dietary acids. Therefore, this study analyses the interaction of Coca Cola consumption and oral mucosal damage. Thirty rats were divided into three groups of 10. The animals received saline (pH 7.0) or HCl acid buffered to pH 2.6 or Coca Cola (pH 2.6) per os with 24-h free access to these solutions. A biopsy was taken from the front of the gingiva and the tongue. Histopathological analysis showed no specific lesion and there were no differences among saline, Coca Cola and HCl groups. Flow cytometric analysis was used to assess proliferative activity. In the HCl acid and Coca Cola groups, cell cycle analysis showed that the effects of Coca Cola and HCl acid in inducing oral mucosal damage are similar. In both Coca Cola [G0/G1, 70.38+/-7.9; S, 28.06+/-10.13; G2/M, 1.62+/-2.80; proliferative index (PI), 28.68+/-7.981 and HCI (G0/G1, 67.7+/-18.9; S, 27.8+/-17.5; G2/M, 4.4+/-3.8; PI, 30.9+/-20.98), the rat cell population G0/G1 and G2/M phases were found to be low (p < 0.05) and the cell population S and PI phases were found to be significantly elevated compared with the control group (p < 0.05) (G0/G1, 86.92+/-8.69; S, 9.8+/-1.21; G2/M, 3.25+/-2.87; P1, 13.2+/-8.7). This result was reflected in the proliferative index, which is used as a measure of the regeneration index. The data show that Coca Cola and HCl acid have similar proliferative and regenerative effects on oral mucosa, and it is possible that their regenerative effects are caused as a result of an irritant effect.

Scintigraphic evaluation of healing response after heterograft usage for alveolar extraction cavity.

OBJECTIVE: Reconstruction of bone defects remains an important problem in oral and maxillofacial surgery. Restoration of defect sites with various grafting materials is a valuable approach to the solution of this problem. The aim of this study was to evaluate the effects of the use of heterografts on osteoblastic activity by means of a radionuclide technique. STUDY DESIGN: The postextraction alveolar cavities of impacted mandibular third molars on 22 patients were used as a healing model for this study. Granulated freeze-dried heterograft material of bovine origin was used on 11 patients; the other 11 patients constituted a control group. On each patient, three-phase bone scans were performed on postoperative days 7 and 28. RESULTS: Although dynamic and blood pool studies showed similar patterns with respect to the mean values of asymmetry ratios of operation sites to the contralateral sides for the 7th- and 28th-day scans, static-phase bone scans revealed that healing response through osteoinduction was more prominent in the study group than in the control group. A significant increase in the mean value of the ratio from the first scan to the second was observed on static images in the study group (first scan, 1.6 +/- 0.2; second scan, 2.0 +/- 0.5; p < 0.05). However, the same ratio failed to show any significant change in the control group (first scan, 1.5 +/- 0.2; second scan, 1.5 +/- 0.3; p > 0.05). CONCLUSION: Static-phase bone scintigraphy showed that when freeze-dried heterograft material is used to fill alveolar extraction cavities, it stimulates osteoblastic activity, which in turn leads to acceleration of the healing process and helps to maintain the linearity of bony structure. Moreover, radionuclide study can be used to evaluate the viability of freeze-dried heterografts in the 4th postoperative week, at which time no additional increase in perfusion resulting from surgical trauma was found in our series.

Clinical and electron microscope comparison of silk sutures and n-butyl-2-cyanoacrylate in human mucosa.

The use of tissue adhesives as an alternative to or replacement for sutures in wound closure has long been an area of interest. One of these tissue adhesives is a cyanoacrylate. In 15 patients, who underwent root resections of the upper incisors on both sides, the incision lines were closed with silk sutures on one side and by n-butyl-2-cyanoacrylate on the other side of the frenum. Clinical comparison was made on the 1st, 2nd, 3rd, 7th, 14th and 21st postoperative days. On the seventh postoperative day following the removal of sutures and the coating, small punch biopsies were obtained from n-butyl-2-cyanoacrylate treated and sutured sides. The tissue specimens were examined under transmission electron microscope. Clinical observations revealed that on the third and seventh postoperative days epithelialization was better on the sides treated with n-butyl-2-cyanoacrylate. On the twenty-first postoperative day it was observed that the scar formation was significantly more marked and there was more local inflammation during the healing period on the sutured side. Electron microscopic observations of both tissue specimens revealed normal ultrastructural morphology.

Comparison of silk sutures and n-butyl-2-cyanoacrylate on the healing of skin wounds. A pilot study.

The synthetic tissue adhesive n-butyl-2-cyanoacrylate (Histoacryl Blue) and silk sutures were compared on the backs of guinea-pigs as the means for closing skin incisions. On the post-operative 3rd, 7th, 14th and 21st days, specimens from each group were obtained and evaluated under light microscopy. Sections were analysed for the degree of inflammation, giant cell reaction, fibroblastic and capillary cell activity and were ranked statistically. The results showed that the silk sutures caused severe inflammatory and giant cell reaction when compared with Histoacryl and the healing process was slower than with n-butyl-2-cyanoacrylate.

[Antibacterial and cytotoxic effects of N-butyl-2-cyanoacrylate used as a tissue adhesive]. / Bir doku yapistiricisi olan N-bütil-2-siyanoakrilat'in antibakteriyel ve sitotoksik özelliklerinin arastirilmasi.

In this study, the antibacterial and cytotoxic effects of a synthetic tissue adhesive called n-butyl-2-cyanoacrylate (Histoacryl) which provide rapid healing in incision in oral surgical procedures were investigated. The antibacterial effects of Histoacryl were tested by using standard reference strains of Streptococcus pyogenes, Streptococcus mitis, Escherichia coli, Pseudomonas aeruginosa and Staphylococcus aureus grown in Mueller-Hinton media (sheep blood supplemented Mueller-Hinton for streptococcus strains) by diffusion technique. The cytotoxic effects were also researched on continuous Vero and primary gingival fibroblast cell cultures by using agar overlay method. In these methods, the inhibition zones produced by Histoacryl were evaluated. As a result, Histoacryl was found to have antibacterial effect on the tested bacteria and produce cytotoxic and cytopathic effects on the tested cell cultures.

Blood flow to palatal mucosal grafts in mandibular labial vestibuloplasty measured by 133Xe clearance technique.

In 11 subjects, the blood flow to alveolar and palatal mucosa was measured by intra-mucosal injection of 133Xe. Later, mandibular labial vestibuloplasty was performed with mucosal grafts in all of them. The use of a stent was omitted. The subjects were followed by clinical observation and by blood flow measurements up to 6 weeks postoperatively. At certain intervals (3 and 10 days, 4 and 6 weeks), 133Xe clearance in the graft was determined. Under normal conditions, the mean blood flows to the alveolar and to palatal mucosa were 53.2 +/- 12.9 and 58.3 +/- 3.5 ml/100 g/min, respectively. The difference between them was statistically insignificant (P greater than 0.05). The graft blood flow was 13.4 +/- 3.2 and 21.7 +/- 15.0 ml/100 g/min on the 3rd and 10th days after operation. The decrease in both compared to normal values was statistically significant (P less than 0.001). The blood flow reached almost normal levels (46.2 +/- 16.9 ml/100 g/min) and above (63.9 +/- 9.7 ml/100 g/min; P less than 0.05) at 4 and 6 weeks after operation, respectively. These results were in agreement with the clinical observations. The palatal donor area healed in 3-5 weeks. The graft showed complete adaptation with the surrounding tissue and healing in 4-6 weeks. Our results also indicated that injections in the graft do not retard graft healing.