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PubMed1983

A comparison of prosthetic materials used to repair abdominal wall defects.

A large abdominal wall hernia, not amenable to primary closure, may require insertion of a prosthesis. The ideal prosthesis maintains strength, is incorporated by surrounding tissues, and does not stimulate adhesions. These qualities vary among available synthetic prostheses. We tested tensile strength, bursting strength, and adhesion formation in response to six materials used in repair of abdominal wall hernias. Adult Sprague-Dawley rats (196) were randomly divided into a control group and six experimental groups. A 4 by 4 cm full-thickness resection of abdominal wall was closed with patches of polypropylene mesh (Marlex), polyglactin 910 mesh (Vicryl), expanded polytetrafluoroethylene (Gore-tex), Dacron-reinforced silicone rubber (Silastic), preserved human dura (PHD), or polypropylene mesh overlying gelatin film (Marlex and Gelfilm, respectively). In controls the 4 cm longitudinal full-thickness incisions were closed primarily. Seven rats randomly selected from each group were sacrificed after 1, 2, 4, and 8 weeks; bursting and tensile strength (tensiometer) and adhesion formation were assessed. There were no differences in bursting strength among the experimental groups at each testing period. Although bursting strength increased linearly with time it was significantly weaker than in controls at 1 and 8 weeks (P less than 0.05). Tensiometric data were inconclusive due to wide variability within the experimental groups. Adhesion formation was moderate to maximal at all evaluation periods for Marlex and Gore-tex. Early adhesion formation was minimal to moderate for both PHD and Vicryl, but later increased with PHD and decreased with Vicryl as this prosthesis was absorbed. No adhesions formed with Marlex and Gelfilm until the gelatin dissolved (1 week), after which the adhesion response was similar to that with Marlex alone. No adhesions formed after Silastic implantation, but graft extrusion and evisceration were common (75%). Controls had no adhesions at all evaluation periods. Wound strength was similar for all prosthetic materials. Absorbable prosthetic Vicryl provided the best long-term protection against adhesions.

Abdominal Muscles↗
PubMed2001

Long-term results of guided tissue regeneration therapy with non-resorbable and bioabsorbable barriers. I. Class II furcations.

BACKGROUND: The aim of this 5-year follow-up study was to clinically and radiographically evaluate the long-term results after guided tissue regeneration (GTR) therapy of Class II furcation defects using non-resorbable and bioabsorbable barriers. METHODS: Nine pairs of contralateral Class II furcation defects were treated in 9 patients with advanced periodontitis. Within each patient, one defect received a non-resorbable (expanded polytetrafluoroethylene [ePTFE]; control, C) barrier and the other a bioabsorbable (polyglactin 910; test, T) barrier by random assignment. At baseline, 6, and 60 +/- 3 months after surgery, clinical parameters and standardized radiographs were obtained. Gain of bone density within furcation areas was assessed using subtraction radiography. RESULTS: Six and 60 months after GTR therapy, statistically significant (P <0.05) horizontal attachment (CAL-H) gain was observed in both groups (C6: 1.7 +/- 0.8 mm; C60: 1.6 +/- 1.2 mm; T6: 2.0 +/- 0.7 mm; T60: 2.2 +/- 0.9 mm). However, 1 furcation assessed as Class I six months after GTR therapy with a bioabsorbable barrier had progressed to Class III after 5 years, and in another patient, 5 years after placement of an ePTFE barrier, 1 furcation had lost all the CAL-H gain that had been observed at 6 months. Subtraction analysis revealed similar area gain in both groups 6 and 60 months postsurgically (C6: 0.3 +/- 0.5; C60 1.0 +/- 1.7; T6: 0.4 +/- 0.4; T60: 1.1 +/- 1.7). CONCLUSIONS: CAL-H gain achieved after GTR therapy in Class II furcations was stable after 5 years in 16 of 18 defects. The study failed to show a statistically significant difference in stability of CAL-H gain between control and test groups 5 years after GTR therapy.

Absorbable Implants↗
PubMed1992

Spatial and temporal changes in compliance following implantation of bioresorbable vascular grafts.

Compliance matching between the host vessel and vascular grafts used for small-diameter arterial replacements is thought to be important for long-term patency. However, currently available grafts elicit fibroplastic reactions, resulting in decreasing compliance with time after implantation. Bioresorbable prostheses elicit ingrowth of myofibroblasts containing abundant contractile elements. This led us to investigate whether compliance of implanted bioresorbable prostheses decreased as a function of time and if the kinetics of change correlated with the progression of tissue ingrowth. Woven polyglactin 910 prostheses (10 mm x 4 mm i.d.) were implanted into adult NZW rabbit infrarenal aortas and replicates were harvested serially through 8 months. Control grafts were implanted, and immediately resected. Dynamic compliance was measured at 1-mm axial increments along each explant using a pulse duplicator apparatus which exposed the harvested samples to realistic pulsatile hemodynamics. Compliance was calculated for proximal, mid, and distal segments of each graft and averaged at each time point by grouping into control (zero time, n = 3), early (1-4 weeks, n = 13), and late (6-36 weeks, n = 9) explant periods. At late explant periods both proximal and distal compliance were significantly greater than mid graft compliance (p < .02 and p < .03, respectively). There was a significant increase in proximal compliance between early and late explant times (p < .01). Measured increases in mid and distal segment compliance over time did not reach statistical significance. Myofibroblast laden tissue ingrowth into the inner capsule followed macrophage phagocytosis and was nearly complete prior to the time that an increase in compliance was demonstrated. Thus since the major histologic episodes precede the change in compliance, these are not likely initiated by this biomechanical change. We hypothesize the graft resorption coupled with the ingrowth of more compliant tissue likely leads to the increased compliance of the graft material.

Animals↗
PubMed1999

Experimental study of the effect of different meshes on bacterial translocation.

Implantation of intraabdominal biomaterials promotes bacterial translocation (BT). In this study we planned to determine the effect of different types of mesh on the induction of BT. Swiss albino mice were divided into four groups: control, polypropylene (PP), polyglactin 910 (PG), and dura mater (DM). At hour 0, an abdominal wall defect was created in all animals. In the control group the defect was closed primarily. PP, PG, and DM meshes were used to repair the defects such that the intestines were in contact with the mesh in the remaining three groups. BT was evaluated 4, 24, and 48 hours later. At 4 hours total BT increased in the PP group compared with that in the control (p = 0.0321) and DM (p = 0.0098) groups. At 24 hours the PG group had increased BT compared with the controls (p = 0.0392) and the DM group (p = 0.0274), whereas the PP group had increased BT compared with the DM group only (p = 0.0477). At 48 hours both PG and PP groups had increased BT compared with controls (p = 0.0431 and p = 0.0001, respectively); the PP group had also increased BT compared to the DM group (p = 0.001) and the PG group (p = 0.017). In the control, DM, and PP groups there was no intragroup statistical difference. In the PG group there was a significant increase in BT at 24 hours compared to that at 4 hours (p = 0.0274). Prosthetic meshes led to increased BT compared to that with the DM mesh. This effect might be attributed to the different organic and physical properties of the meshes.

Abdominal Muscles↗
PubMed2001

Suture materials and other factors associated with tissue reactivity, infection, and wound dehiscence among plastic surgery outpatients.

The most common complications in plastic surgery are tissue reactivity, infections, and wound dehiscence. In the literature, there are only a few studies with sample sizes large enough and methods of statistical analysis appropriate for evaluating the role of suture materials in inducing such complications. In the 1000 plastic surgery outpatients in this study, the association of different suture materials, individual patient characteristics, surgeon skill, and wound site and length with postoperative wound complications (i.e., tissue reactivity, infection rate, and wound dehiscence) were investigated. No substantial differences were found between the different suture materials and suturing techniques. A moderate increase in the risk of tissue reactivity for silk and polyglactin 910 and a protective effect of thinner internal sutures were observed. In multivariate analysis, such differences were not statistically significant. Male sex [odds ratio (OR), 1.7; 95 percent confidence interval (CI), 1.06 to 2.72] and older age (OR, 2.34; 95 percent CI, 1.36 to 4.05) were found to be the most important risk factors for tissue reactivity and infection rate (male sex: OR, 5.1; 95 percent CI, 1.7 to 15.9; older age: OR, 5.6; 95 percent CI, 1.9 to 16), whereas younger age was associated with an increased risk of dehiscence (OR, 3.06; 95 percent CI, 1.41 to 6.65). Wounds on the lower limbs showed a lower risk of tissue reactivity and wounds on the back a higher risk of dehiscence. Wound length was associated with the risk of tissue reactivity in one-layer sutures (OR, 2.92; 95 percent CI, 1.51 to 5.65). An increased risk of both tissue reactivity (OR, 1.53; 95 percent CI, 1.03 to 2.27) and dehiscence (OR, 2.44; 95 percent CI, 1.1 to 5.43) was observed for operations performed by less-experienced surgeons. Rather than factors related to suture materials and different surgical techniques, and with the exception of surgeon experience, general characteristics of the patients (i.e., sex and age) and of the wounds (i.e., length and site) seemed to be primarily responsible for local wound complications.

Absorbable Implants↗
PubMed1986

A comparison of absorbable and nonabsorbable sutures to vascular response in immature arteries.

Absorbable suture material for microvascular procedures may be superior to nonabsorbable sutures because no foreign body remains at the operative site after suture absorption. We compared Vicryl (polyglactin 910) to a nonabsorbable suture, Prolene, which has been noted to have minimal thrombogenic potency. Patency rates, aneurysm formation, histologies and growth of the distal limb were measured and compared in microvascular anatomoses of immature arteries. Using 8-week-old rats, both femoral arteries (mean external diameter .85 mm) were transected and reanastomosed, using 10-0 suture material (Vicryl and Prolene) on a BV75-3 needle. Thirty rats were included in the study and separated into three harvest groups which were harvested at 4, 8, and 12 weeks. Magnification arteriography of the femoral arteries was performed, as well as standard refill tests. Selected vessels were sent for histologic study using H & E stain. Foot lengths of the rats were measured and compared to preoperative lengths. Prior to harvest, the arteries in the growing animals increased in diameter by 35 percent. Overall patency rates were 68.2 percent for Vicryl and 59.1 percent for Prolene, a non-significant difference. Aneurysm formation was 9.1 percent for Vicryl, and 50.0 percent for Prolene, a significant difference (P less than 0.01). The arteries repaired with Vicryl showed less scar formation, less medial necrosis, and less subintimal hyperplasia. Distal limb lengths showed no difference in the Vicryl and Prolene groups, but both groups were statistically inferior with respect to the unoperated control group. Our study demonstrated Vicryl to be equivalent to Prolene with respect to patency rates, but superior with respect to aneurysm formation and histologic response.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Kinetics of cell proliferation as a function of vascular graft material.

Bioresorbable vascular grafts constructed for polyglactin 910 (PG910) and polydioxanone (PDS) and nonresorbable Dacron were interposed into the infrarenal abdominal aortas of New Zealand White rabbits. The prosthesis/tissue complexes were harvested after 2, 3, 4, 12, and 52 weeks. Seventeen, 9, and 1 h prior to sacrifice, animals received tritiated thymidine (0.5 mCi/kg/dose). All specimens were studied grossly and by light and transmission electron microscopy. Mitotic indices (MI's) were determined by autoradiography for inner capsule myofibroblasts at the proximal, mid, and distal segments of each prosthesis. There were no aortic-related deaths. All grafts were patent with no aneurysmal dilatation. At 4 weeks, PG910 resorption was evidenced by macrophage phagocytosis, less so in PDS while Dacron remained intact. At 12 weeks, the PG910 was completely resorbed while PDS resorption continued. The latter was completely resorbed by 52 weeks. There was no significant difference in MI's between proximal, mid, and distal regions for each graft type. The mitotic index paralleled the rate of prosthetic resorption in both PG910 and PDS groups, as high as 28.34 +/- 23.21 in the former 3 weeks after implantation and significantly higher at 4 weeks (7.58 +/- 2.02 and 7.50 +/- 2.66, respectively) than at 52 weeks (0.72 +/- 0.98 and 1.00 +/- 0.22, respectively) in both groups. The mitotic index in the Dacron group never surpassed 1.22 +/- 0.90. We conclude that higher levels of early cell proliferation in bioresorbable grafts closely parallel the kinetics of prosthetic resorption.

Animals↗
PubMed1998

Nature and attachment of cementum formed under guided conditions in human teeth. An electron microscopic study.

In an attempt at characterizing the nature and attachment of cementum formed under conditions of guided tissue regeneration (GTR) in humans, front teeth from 4 patients aged 42 to 72 years were examined at the electron microscopic level. All teeth were affected by complex periodontitis associated with advanced loss of periodontal support. Roots were surgically planed and notched, but not chemically conditioned. Either the mesial or distal surface of each tooth represented the experimental site and was covered with a biodegradable polyglactin 910 barrier, while the opposite approximal surface served as control. Following 3 months of healing, teeth were removed together with surrounding periodontal tissues including some alveolar bone. These blocks were fixed histologically, decalcified, embedded in epoxy, and sectioned for examination in the scanning (backscatter mode) and transmission electron microscope. Both experimental and control sites disclosed 2 types of regenerative cementum that seemed to be formed by cells resembling cementoblasts. The first type was characterized by a thin fringe of collagen fibrils which were arranged perpendicular to the root surface and appeared mineralized in a zone extending about 1 to 3 microm from the dentin. The second type occurred as thick patches which revealed scattered cementocytes and sheets of collagen fibrils oriented mainly parallel to the root surface, running both circularly and axially. In both situations, a continuous, thin, electrondense layer was interposed between newly formed cementum and preexisting radicular hard tissues. Interdigitation of collagen fibrils from cementum and dentin, such as observed along the natural cemento-dentinal junction, did not occur. Thus, regenerative cementum laid down in humans under guided conditions on previously diseased and planed, but not otherwise treated root surfaces shares some morphologic features with cementum formed during spontaneous repair of root resorptions. However, unlike in the course of such repair, a fibrous attachment of new cementum resembling the natural cemento-dentinal junction does not seem to be regenerated under guided conditions.

Absorbable Implants↗
PubMed2002

Long-term results of guided tissue regeneration therapy with non-resorbable and bioabsorbable barriers. II. A case series of infrabony defects.

BACKGROUND: The aim of this 5-year follow-up case series was to clinically and radiographically evaluate the long-term results after guided tissue regeneration (GTR) therapy of infrabony defects using non-resorbable and bioabsorbable barriers. METHODS: In 12 patients with advanced chronic periodontitis 12 pairs of contralateral infrabony defects were treated. Within each patient one defect received a non-resorbable (expanded polytetrafluoroethylene [ePTFE]; control: C) and the other a bioabsorbable (polyglactin 910; test: T) barrier by random assignment. At baseline and at 6 and 60 +/- 3 months after surgery clinical parameters and standardized radiographs were obtained. Gain of bone density within infrabony defects was assessed using subtraction radiography. RESULTS: Eight of 12 patients were available for the 60-month reexaminations. Six and 60 +/- 3 months after GTR therapy statistically significant (P < 0.05) vertical attachment (CAL-V) gain was observed in both groups (C6:2.6 +/- 1.4 mm; C60: 1.6 +/- 1.5 mm; T6:3.0+/- 1.7 mm; T60: 3.0 +/- 0.7mm). However at 60 months, 2 infrabony defects in the control group had lost all the attachment that had been gained 6 months after therapy and a clinically relevant but statistically in significant mean CAL-V loss of 1.0 +/- 2.1 mm was observed from 6 to 60 months. The case series failed to show statistically significant differences between test and control regarding CAL-V gain 60 months after surgery. Also subtraction analysis failed to reveal statistically significant differences regarding density gain between both groups 6 and 60 months postsurgically (C6: 26.4 +/- 54.2; C60 62.8 +/- 112.7; T6: 68.7 +/- 72.8; T60. 84.1 +/- 83.6). CONCLUSIONS: CAL-V gain achieved after GTR therapy in infrabony defects using both non-resorbable and bioabsorbable barriers was quite stable after 5 years in 14 of 16 defects.

Absorbable Implants↗
PubMed1994

Grafting of cultured uroepithelium and bladder mucosa into de-epithelialized segments of colon in rabbits.

Urinary tract reconstruction using bowel can result in acid-base and electrolyte abnormalities. We tested the feasibility of grafting bladder mucosa and urothelial cells grown on a biodegradable polyglactin 910 scaffold onto de-epithelialized segments of bowel in the rabbit. A segment of de-epithelialized colon was either grafted with cultured urothelium on a collagen mesh scaffold (12 rabbits) or with free bladder mucosa (11 rabbits). In 10 rabbits that served as a control group another segment of bowel was isolated and de-epithelialized. No urothelial or bowel epithelial growth was present 4 weeks later in 10 of the isolated de-epithelialized colonic segments grafted with the cultured urothelium. In 2 segments a minute focus of epithelium staining positively for anticytokeratin antibodies AE1 and AE3 was seen but this could not be histologically differentiated as either urothelium or native colonic epithelium. All 7 surviving animals that underwent a bladder mucosal graft had viable urothelium at sacrifice 30 days postoperatively. In 2 of the 7 rabbits microscopic nests of colonic epithelium were also found underneath the urothelial layer. Of the 7 internal controls 6 had no evidence of bowel epithelial regrowth 4 weeks after de-epithelialization. This study demonstrated that a confluent layer of urothelial cells could be grown in culture using a scaffold of biodegradable mesh and rat tail collagen. We also showed that bladder mucosal grafts can be grown on de-epithelialized bowel segments. We were unable to graft successfully cultured urothelial cells onto a de-epithelialized bowel segment. Further improvement in understanding the role of the submucosal matrix in cell growth may lead to future success in covering large segments of de-epithelialized bowel with autologous urothelium.

Animals↗
PubMed2006

Healing response of apicomarginal defects to two guided tissue regeneration techniques in periradicular surgery: a double-blind, randomized-clinical trial.

AIM: To compare healing responses to periosteal sliding grafts and polyglactin 910 periodontal mesh used as guided tissue regeneration (GTR) materials/techniques when both periapical and periradicular bone loss are present. METHODOLOGY: Thirty patients with suppurative chronic apical periodontitis with apicomarginal communication were selected and allocated randomly into two groups according to the barrier technique to be used during periradicular surgery: periosteal graft group (n = 15) and bioabsorbable membrane group (n = 15). Clinical and radiological evaluations were completed prior to surgery, a week later and every 3 months after surgery up to 12 months to measure the periodontal pocket depth (PD), clinical attachment level (CAL), gingival margin position (GMP), size of periapical lesion, percentage reduction of the periapical rarefaction, and periapical healing. RESULTS: Both groups showed highly significant (P < 0.001) reductions in periodontal PD, CAL and size of periapical lesion at 12 months whilst GMP was unaltered. No significant difference between the experimental groups was evident for these parameters, or for the percentage reduction of size of the periapical lesion and clinical-radiographic healing. CONCLUSION: Guided tissue regeneration applied to apicomarginal defects using sliding periosteal grafts and use of bioabsorbable membranes led to similar enhancements of the clinical outcome of periradicular surgery in terms of periapical healing, gain of periodontal support, PD reduction and minimal recession of the gingival margin.

Absorbable Implants↗
PubMed1995

Vicryl-mesh wrap for the implantation of hydroxyapatite orbital implants: an animal model.

OBJECTIVE: To evaluate host fibrovascularization of hydroxyapatite orbital implants wrapped in sclera or in Vicryl (polyglactin 910) mesh in a rabbit model. NUMBERS: Eight adult New Zealand white rabbits that received hydroxyapatite orbital implants wrapped in homologous donor sclera (four animals) or Vicryl mesh (four animals). INTERVENTIONS: The rabbits had one eye enucleated and then received a 12-mm hydroxyapatite implant wrapped in sclera or Vicryl mesh. Magnetic resonance imaging (MRI) and bone scintigraphy were done to assess host fibrovascularization of the implant 4, 8, 12 and 20 weeks after implantation. Two animals (one in each group) were killed at each of these times, and the implant was removed for histopathological examination. MAIN OUTCOME MEASURES: Enhancement on MRI, uptake on bone scintigraphy, fibrovascularization seen on histopathological examination. RESULTS: The degree of fibrovascularization was substantial in all the specimens but appeared greater in the Vicryl-mesh-wrapped implants in the first 12 weeks after implantation on both histopathological and MRI studies. At 20 weeks these findings were similar in the two groups. A granulomatous foreign-body giant-cell reaction to both the Vicryl mesh and the implant itself was present up to 8 weeks after implantation. Bone scans showed only grade 1+ activity in all the implants. CONCLUSIONS: Host fibrovascularization in the rabbit appears to occur to a greater degree in Vicryl-mesh-wrapped hydroxyapatite implants than in those wrapped in donor sclera during the first 12 weeks after implantation. Vicryl mesh appears to be an acceptable alternative wrap for the hydroxyapatite implant, eliminating the need for donor sclera and its potential risks of transmissible diseases.

Animals↗
PubMed1998

Evidence for healing of interproximal intrabony defects after conventional and regenerative therapy: digital radiography and clinical measurements.

In 24 patients with advanced periodontitis 38 interproximal intrabony defects were treated by conventional surgery (C; n = 8) or guided tissue regeneration (GTR) using expanded polytetrafluoroethylene (G; n = 17) or Polyglactin 910 barriers (V; n = 13). Presurgically (BL), 6 and 12 months postsurgically clinical parameters (GI, PII, PPD, PAL-V) and 36 standardized radiographs were obtained generating 72 pairs (36 BL/6 months; 36 BL/12 months). Using linear measurements on the radiographs and subtraction analysis, bony fill within the defects was assessed. Intrasurgically the extension of the intrabony defects was measured. Statistically significant (p < 0.05) attachment gain was found after 6 (C: 2.4 +/- 1.6 mm; G: 3.2 +/- 1.6 mm; V: 3.4 +/- 1.5 mm) and 12 months in all groups (C: 2.4 +/- 1.7 mm; G: 3.1 +/- 1.7 mm; V: 4.0 +/- 1.7 mm). Thirty-nine of 72 pairs of radiographs were unsuitable for subtraction analysis. Significant (p < 0.05) bony fill was observed at 6 (C: 0.3 +/- 1.0 mm; G: 0.7 +/- 1.2 mm; V: 0.9 +/- 1.2 mm) and 12 months (C: 0.0 +/- 1.1 mm; G: 1.4 +/- 1.5 mm; V: 1.5 +/- 1.7 mm) only after GTR surgery. GTR therapy yielded significantly more bony fill than conventional surgery 12 months postsurgically (p < 0.1). Bony fill (linear measurement) was influenced by age, smoking, baseline bone loss and PAL-V gain (p < 0.0001). Significantly more radiographs taken with potentially unstable support of the filmholder were not suitable for subtraction analysis than those with stable support (p < 0.05). Bony gain (subtraction analysis) was positively modulated by bony fill (linear measurement) and use of biodegradable barriers (p = 0.002). There is a correlation between PAL-V gain and bony fill (linear measurement). Smoking impairs attachment gain and bony fill. Potentially stable support of the filmholder provided radiographs suitable for subtraction analysis.

Adult↗
PubMed1997

Guided tissue regeneration with non-resorbable and biodegradable barriers: 6 months results.

The aim of the present study was to compare the effects of guided tissue regeneration (GTR) with non-resorbable (ePTFE [G]) and biodegradable barriers (Polyglactin 910 (V)). In 20 patients, providing 25 pairs of symmetrical periodontal defects (7 pairs of interproximal intrabony lesions, 12 pairs of degree II and 6 pairs of degree III furcation involvement), each defect was randomly assigned to treatment with either non-resorbable (control) or biodegradable (test) devices. At baseline and 6 months after surgery, clinical measurements (GI, PPD, PAL-V, PAL-H, P1I) and standardized radiographs were obtained. On the radiographs, the linear distances from the cemento-enamel junction (CEJ) to the alveolar crest (AC), and from the CEJ to bottom of the bony defect (BD) were measured using a computer-assisted analysing method (LMSRT). Both treatments revealed a significant (p < 0.05) PPD reduction (-2.90 +/- 1.33 mm (V), -2.71 +/- 1.41 mm (G)), PAL-V gain (1.78 +/- 1.27 mm (V), 1.46 +/- 1.35 mm (G)), PAL-H gain (2.00 +/- 0.82 mm (V), 1.60 +/- 0.59 mm (G)), and radiographic changes (CEJ-AC: 0.48 +/- 0.75 mm (V), 0.73 +/- 0.92 mm (G); CEJ-BD: -0.76 +/- 0.79 mm (V), -0.41 +/- 0.72 mm (G)) after 6 months. The mean differences between the changes for test and control were not significant for most clinical and radiographic parameters. Similar clinical and radiographic results were found 6 months after surgical treatment using either non-resorbable or biodegradable barriers. More favorable results concerning PAL-H gain could be observed with biodegradable barriers after 6 months. Therefore, based on these results, the use of biodegradable barriers in GTR may be recommended and, thereby, a surgical re-entry to remove non-resorbable barriers can be avoided.

Adult↗
PubMed1987

Compound polyglactin 910/polypropylene small vessel prostheses.

This study evaluated morphologic and functional characteristics of tissue reactions to compound prostheses of 69% absorbable polyglactin 910 (PG910) and 31% nonabsorbable polypropylene in the rabbit. Forty-two woven PG910/polypropylene prostheses (24 X 4 mm internal diameter) implanted into rabbit infrarenal aortas were harvested after 2 weeks to 12 months. Each explant was photographed and sectioned for light microscopy and transmission and scanning electron microscopy. Randomly selected explants underwent either compliance and bursting strength measurements or assays of production of prostacyclin and thromboxane metabolites by luminal surfaces of both regenerated conduits and normal control aortas in response to administered sodium arachidonate. Results showed 100% patency with no aneurysms and 2% stenoses (1 of 42 prostheses). Confluent endothelial-like cellular luminal surfaces covering oriented smooth muscle-like myofibroblasts comprised the inner capsules whose thicknesses stabilized at 1 to 2 months. Only residual polypropylene remained in the prostheses after 2 months. Compliance studies reflected a 0.65 mm (14%) change over a pressure range of 0 to 160 mm Hg. All regenerated prosthesis-tissue complexes had bursting strengths greater than the proximal perianastomotic native aortas, which burst between 600 and 2000 mm Hg. At 1 month the rate of production of 6-keto-PGF1 alpha per square millimeter of surface area of experimental segments was normal. Production of 6-keto-PGF1 alpha by experimental segments at 3 months had increased fourfold whereas thromboxane B2 (TxB2) production remained unchanged. The 6-keto-PGF1 alpha/TxB2 ratio increased from 1 to 4 months. This study demonstrates clinically efficacious morphologic, mechanical, and biochemical characteristics of PG910/polypropylene-elicited vascular prosthesis-tissue complexes.

6-Ketoprostaglandin F1 alpha↗
PubMed1997

Postoperative exposure of bioresorbable GTR membranes: effect on healing results.

The goal of this investigation was to evaluate the effect of postoperative exposure of two different bioresorbable membranes on the guided tissue regeneration (GTR) healing results compared to nonexposed sites. In each of 25 patients one pair of contralateral intrabony lesions was treated either with polylactic acid (PLA) or polyglactin 910 (PG-910) membranes. Postoperative exposure occurred in 9 PLA and 13 PG-910 sites. Standardized clinical [papillary bleeding index (PBI), gingival recession (REC), probing pocket depth (PPD), probing attachment level (PAL)] and radiographic examinations (digital subtraction radiography) were performed immediately before (baseline) and 6 and 12 months postoperatively (p.o.). Subgingival bacterial samples from surgical sites were evaluated by culture at baseline, 6 weeks, and 6 and 12 months p.o. Six months after surgery the changes (delta) of REC were significantly (P < or = 0.05) greater in exposed than in nonexposed sites, independently of the membrane material (median): exposed sites, delta REC = -1 mm; nonexposed sites, delta REC = 0.0 mm. However, 12 months p.o. no significant differences were found due to a decrease in the initial recessions in exposed sites. Although a higher percentage of exposed than nonexposed sites harbored periodontal pathogens 6 weeks p.o. at the gingiva-faced membrane surface, membrane exposure did not have a significant negative effect on delta PPD, delta PAL, or radiographic bone density changes 6 and 12 months p.o. Both membranes showed significant gains in PAL and bone density in both exposed and nonexposed sites. In conclusion, this study demonstrates that with consistent infection control the postoperative exposure of PLA and PG-910 membranes has no significant negative effect on the regeneration outcome, although higher initial gingival recessions must be expected than in the nonexposed sites. However, in exposed sites plaque and infection control were clearly impeded by the rough, exposed membrane surfaces and by the initially negative gingival morphology.

Adult↗
PubMed2005

Laparoscopic suturing: effect of instrument handling on suture strength.

BACKGROUND AND PURPOSE: In open surgery, handling of suture at any position other than the end is discouraged because of evidence that handling deforms and weakens the material. The limited operative field of laparoscopic surgery necessitates repeated instrument handling of suture, and the effect of such handling has not been investigated. We assessed the effect of trauma imposed on various suture materials by laparoscopic needle holders and forceps. Also, the ideal suturing technique (interrupted v continuous) according to the physical characteristics of the suture material and the optimal length for laparoscopic sutures were determined. MATERIALS AND METHODS: Sutures of 2-0 and 3-0 polyglactin 910 and 2-0 poliglecaprone 25 were tested. Controlled damage was inflicted by grasping the suture for 1 second between the jaws of either toothed laparoscopic grasping forceps or a laparoscopic needle holder at a pressure of 45 MPa. Blind physical testing was then performed using a computer-controlled tensile testing system. The length and proportion of suture extension prior to breaking and the tensile strength were measured. Samples of undamaged and controlled damaged specimens, before and after breakage, were examined by scanning electron microscopy (SEM). RESULTS: The mean percentage extension in the control group was 46.3 mm for 3-0 Monocryl, 26.3 mm for 3-0 Vicryl, and 28.1 mm for 2-0 Vicryl. The mean tensile strengths were 47.9 N, 42.4 N, and 70.4 N for 3-0 Monocryl and 3-0 and 2-0 Vicryl, respectively. The 3-0 Monocryl and 3-0 Vicryl had significantly reduced tensile strength after damage compared with control sutures, whereas 3-0 Vicryl and 2-0 Vicryl had significantly impaired extension. After infliction of controlled damage with laparoscopic needle holders, the percent extension of damaged sutures was significantly less than that of undamaged sutures. Tensile strength was significantly lower for 3-0 Vicryl and 3-0 Monocryl after damage than before. The handling of Monocryl by laparoscopic needle holders and graspers produced punched-out defects and scratch marks, respectively. A number of damaged 2-0 and 3-0 Vicryl samples from the laparoscopic needle holder group showed disruption or unravelling of the braided filaments. CONCLUSION: We expect that our results underestimate the potential effect on suture strength and extension inflicted by laparoscopic suturing. The exact length of suture material cannot be recommended from the findings. However, interrupted sutures should be preferred, particularly for long suture lines. In addition, the findings support the use of laparoscopic graspers in preference to needle holders. The combination of a grasper in one hand and needle holder in the other is ideal. Finally, urologists initially embarking on laparoscopic reconstruction must take meticulous care in their suturing technique and, in particular, the number of times and force with which the suture is grasped.

Dioxanes↗
PubMed2000

The effect of chlorhexidine mouthrinses on early bacterial colonization of guided tissue regeneration membranes. An in vivo study.

BACKGROUND: Different membrane materials accumulate varying amounts of bacteria when exposed in the oral cavity, due to their textural and structural surface characteristics. The aim of the study was to evaluate the effect of chlorhexidine mouthrinses on the in vivo early bacterial colonization of 3 different guided tissue regeneration membrane materials. METHODS: Rectangular-shaped strips cut from 3 periodontal membranes (expanded polytetrafluoroethylene, polyglactin 910, and polylactic acid) were glued to removable devices adapted to the 2 upper quadrants in 8 dental students. In each student 1 quadrant was randomly selected as test side while the other served as control side. The experiment was divided in 2 phases: in the first phase plaque accumulation was followed for 4 hours while the second accumulation was followed for 24 hours. During the 4-hour experiment, students rinsed the test device twice (immediately following device application and after 2 hours) with 0. 12% chlorhexidine solution. The control device was rinsed with saline. In the second phase, students rinsed the test device with chlorhexidine and the control devices with saline 3 times (after device application and at 8 and 16 hours). Both the 4-hour and the 24-hour specimens were processed for scanning electron microscopy analysis. Fifty-four fields (at 200x magnification) were randomly selected and analyzed on each strip. Magnification was increased to determine the presence and morphotype of bacteria. The presence or absence of bacteria was assessed in a binomial fashion: the field was bacteria-positive when bacteria constituted the deposits covering the membrane surface. The microscopic field was negative (bacteria-negative) when no bacteria were observed. Bacteria-positive fields showing rods and filaments as prevalent morphotypes were recorded as rod-positive fields. RESULTS: The results of data analysis suggest that bacterial contamination of membrane materials is significantly reduced by treatment with chlorhexidine. They also suggest that other variables affect plaque accumulation as well; i.e., the time allowed (4 versus 24 hours) and the different membrane materials. The interaction between these 2 variables is also highly significant, thereby indicating a different rate of plaque accumulation on different materials, irrespective of the treatment with chlorhexidine. CONCLUSIONS: It was concluded that chlorhexidine mouthrinses may be effective in reducing and delaying the early bacterial accumulation on membrane materials although they are not able to fully prevent it. Membrane surface characteristics seem to be a more critical factor than the use of chlorhexidine, in influencing bacterial adhesion and colonization of barrier materials.

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