The effect of various concentrations of collagen barrier on periodontal wound healing

Effects of Paraspinal Intramuscular Injection of Atelocollagen in Patients with Chronic Low Back Pain: A Retrospective Observational Study

Background/Objectives: Atelocollagen is used for soft tissue repair and reconstruction by replacing defective or damaged muscles, membranes, ligaments, and tendons. This study aimed to evaluate the clinical efficacy and safety of additional paraspinal intramuscular injection of atelocollagen on lumbar epidural steroid injection for reducing pain and improving functional capacity of patients with chronic low back pain (CLBP). Methods: We retrospectively enrolled 608 consecutive patients with CLBP who received lumbar epidural steroid injection with or without additional paraspinal intramuscular injection of atelocollagen. The Numerical Rating Scale and the Oswestry Disability Index were used to assess pain and functional capacity, respectively, before the procedure, and three months after the injection. Also, we analyzed the relationship between the additional paraspinal intramuscular injection of atelocollagen and the success rate. Results: Both Numerical Rating Scale and the Oswestry Disability Index scores were significantly reduced in both groups at three months after injection. However, there was a significant difference between the two groups. Furthermore, the success rate was significantly higher in the additional paraspinal intramuscular injection of atelocollagen group. Conclusions: This study's results showed that additional paraspinal intramuscular injection of atelocollagen on lumbar epidural steroid injection reduced pain and improved functional capacity for patients with CLBP. Therefore, the paraspinal intramuscular injection of atelocollagen may be a promising option for the treatment of patients with CLBP.

Buccal plate preservation with immediate post-extraction implant placement and provisionalization in anterior maxillary tooth: Preliminary results of a new technique using Teruplug collagen

BACKGROUND

Bone resorption and remodelling are inevitable results of dental extraction and begin immediately after the extraction procedure. The buccal plate is especially predisposed to these phenomena, and if affected, may result in an increased risk of facial soft-tissue recession and other adverse clinical effects that may decrease the predictability of implant placement or impair the final aesthetic result.

PERPOSE

The application of Teruplug collagen to prevent buccal plate resorption technique is a new technique aimed at maintaining or improving the appearance of the soft and hard tissues after dental extraction procedures.

METHODS

All patients underwent teeth extraction and buccal plate preservation followed by immediate implant placement and provisionalisation using Teruplug collagen. The distance from the external surface of the labial bone to the buccal surface of the implant was measured immediately after placement 6 months and 12 months using computed tomography(CT) images. The aesthetic outcome of 35 implant supported dentures was evaluated by the pink aesthetic score (PAS). Patient aesthetic satisfaction was investigated by a visual analogue scale (VAS).

RESULTS

In a four-wall intact socket, this approach is aimed at optimising the ability of the Teruplug collagen to improve regeneration and maintain or improve labial/buccal contours without interfering with the natural healing capability of the alveolus after extraction and implant placement. During the different observation period, there were no major biologic or prosthodontic complications as determined by a clinical examination at each follow-up visit.

CONCLUSIONS

Buccal plate preservation as described may help to maintain or improve the appearance and contours of the ridge after tooth extraction, laying the groundwork for optimal functional and aesthetic replacement of the missing tooth with an implant-supported prosthesis.

Role of periosteum in alveolar bone regeneration comparing with collagen membrane in a buccal dehiscence model of dogs

To investigate the role of periosteum on the treatment of buccal dehiscence defects comparing with collagen membrane in canine model. Bilateral dehiscence-type defects at the buccal side on the distal root of the lower 3rd/4th premolars were created in six beagle dogs with a total of 24 defects and assigned into three groups: Group A: blood clot in an untreated defect; Group B: deproteinized bovine bone material (DBBM) covered with an absorbable membrane; Group C: DBBM covered with the periosteum. The structural parameters for trabecular architecture and vertical bone regeneration were evaluated. Histological and histomorphometric evaluation were carried out to observe new bone formation and mineralization in the graft site. Immunohistochemical analysis was performed to identify the expression of osteopontin (OPN) and osteocalcin (OCN) at postoperative 3 months. Group C achieved greater vertical alveolar bone gain than that of group A and group B. The periosteum-covered group showed significantly greater new bone formation and accelerated mineralization. The greater immunolabeling for OPN and OCN was observed in group C than in group A. Periosteal coverage has explicit advantages over collagen membranes for the quality and quantity of new bone regeneration in dehiscence defects repairing.

Complications in bone-grafting procedures: Classification and management

Bone-regenerative interventions aiming to restore deficient alveolar ridges, such as the use of block grafts or through the application of guided bone-regeneration principles, have reported positive outcomes in the published scientific literature. These interventions, however, are invasive, and hence, intraoperative and/or postoperative complications may occur. The types of complications and their severity may vary from the exposure of the biomaterial (membrane or graft) to postsurgical infections, neurosensorial disturbances, occurrence of hemorrhage, and pain, etc. The aim of the present narrative review was to search the available scientific evidence concerning the incidence of these complications, their effect on treatment outcomes, their clinical management and, finally, strategies aimed at prevention. Exposure of the barrier membrane or the block graft is the most common complication associated with oral regenerative interventions. To manage these complications, depending on the extent of the exposure and the presence or absence of concomitant infections, therapeutic measures may vary, from the topical application of antiseptics to the removal of the barrier membrane or the block graft. Regardless of their treatment, the occurrence of these complications has been associated with patient selection, with compliant patients (eg, nonsmokers) having a lower reported incidence of complications. Similarly, surgical factors such as correct flap elevation and a tensionless closure are of obvious importance. Finally, to prevent the incidence of complications, it appears prudent to utilize whenever possible less invasive surgical interventions.

Impact of different regenerative techniques and materials on the healing outcome of endodontic surgery: a systematic review and meta-analysis

BACKGROUND

Regenerative techniques are increasingly applied in endodontic surgery, but different materials used in regenerative techniques may have varying impacts on wound healing.

OBJECTIVES

This study evaluated the effects of different regenerative techniques and materials on the outcome of endodontic surgery.

PARTICIPANTS

patients with persistent periapical lesions, treated with root-end surgery.

CONTROL

endodontic surgery without the use of regenerative techniques/materials.

INTERVENTION

endodontic surgery with the use of regenerative techniques/materials.

OUTCOME

combined clinical and radiographic results.

METHODS

PubMed, Web of Science, Embase, SinoMed and the CENTRAL Cochrane were searched up to 10th July 2020, followed by a manual search. Detailed eligibility criteria were applied. Cochrane's risk-of-bias tool 2.0 was used to assess the risk of bias of the eligible studies. Meta-analysis was conducted using RevMan software. Subgroup analyses were performed based on the regenerative materials used in endodontic surgery.

RESULTS

Eleven eligible randomized controlled trials (RCTs) were included in the meta-analysis: two had a low risk of overall bias, and nine had some concerns of overall bias. Generally, the use of regenerative techniques significantly improved the outcome of endodontic surgery (risk ratio [RR]: 0.42; 95% confidence interval [CI], 0.26-0.68; P < 0.001). On subgroup analysis, the use of expanded polytetrafluoroethylene (e-PTFE) membranes alone had no added benefits (RR: 2.00; 95% CI, 0.22-18.33; P = 0.54). The application of collagen membranes or autologous platelet concentrates (APCs) alone was associated with a trend for better outcomes (RR: 0.51; 95% CI, 0.20-1.25; P = 0.14) (RR: 0.55; 95% CI, 0.18-1.71; P = 0.30). The combined use of collagen membranes and bovine-derived hydroxyapatite significantly improved the outcome (RR: 0.35; 95% CI, 0.17-0.75; P = 0.007).

DISCUSSION

This systematic review evaluated the effects of collagen membranes, e-PTFE membranes, APCs and bone grafting materials, providing detailed information about the risks and benefits of using each regenerative technique/material or its combination in endodontic surgery.

CONCLUSIONS

Regenerative techniques improve periapical lesion healing after endodontic surgery. The combined use of collagen membranes and bovine-derived hydroxyapatite may be beneficial as an adjunct to endodontic surgery. In contrast, the positive efficacy of e-PTFE membranes or APCs alone remains doubtful.

Influence of biodegradable polymer membrane on new bone formation and biodegradation of biphasic bone substitutes: an animal mandibular defect model study

Purpose

The purpose of this study was to evaluate the influence of biodegradable polycaprolactone membrane on new bone formation and the biodegradation of biphasic alloplastic bone substitutes using animal models.

Materials and methods

In this study, bony defect was formed at the canine mandible of 8 mm in diameter, and the defects were filled with Osteon II. The experimental groups were covered with Osteoguide as barrier membrane, and the control groups were closed without membrane coverage. The proportion of new bone and residual bone graft material was measured histologically and histomorphometrically at postoperative 4 and 8 weeks.

Results

At 4 weeks, the new bone proportion was similar between the groups. The proportion of remaining graft volume was 27.58 ± 6.26 and 20.01 ± 4.68% on control and experimental groups, respectively (P < 0.05). There was no significant difference between the two groups in new bone formation and the amount of residual bone graft material at 8 weeks.

Conclusion

The biopolymer membrane contributes to early biodegradation of biphasic bone substitutes in the jaw defect but it does not affect the bone formation capacity of the bone graft.

Evaluation of Biocompatibility of Different Membrane Surfaces Using Unrestricted Somatic Stem Cells

BACKGROUND/AIM

Results of Guided Bone Regeneration (GBR) primarily depend on the membrane used. The aim of this study was to compare biocompatibility of different absorbable and non-absorbable membranes by using unrestricted somatic stem cells (USSCs) as an indicator for biocompatibility.

MATERIALS AND METHODS

Five absorbable membranes (Bio-Gide®, RESODONT®, GENTA-FOIL resorb®, BioMend® and BioMend® Extend™) and one non-absorbable alternative (GORE-TEX®) were colonized with USSCs. After 24 h, 3 days and 7 days, cell proliferation, cell viability, and cytotoxicity were assessed. Moreover, cell morphology was evaluated by electron microscopy.

RESULTS

Significantly higher cell proliferation and cell viability rates were observed in Bio-Gide® and RESODONT® membranes. Cell toxicity was highest on GENTA-FOIL resorb® membranes. The electron microscopical assessment showed a better cell attachment on porous surfaced membranes.

CONCLUSION

This study shows that USSCs can be used for assessments of biocompatibility, and that absorbable membranes with collagenous composition and porous structure tend to positively impact biocompatibility and enhance cell proliferation.

A Novel Bilayer Polycaprolactone Membrane for Guided Bone Regeneration: Combining Electrospinning and Emulsion Templating

Guided bone regeneration is a common dental implant treatment where a barrier membrane (BM) is used between epithelial tissue and bone or bone graft to prevent the invasion of the fast-proliferating epithelial cells into the defect site to be able to preserve a space for infiltration of slower-growing bone cells into the periodontal defect site. In this study, a bilayer polycaprolactone (PCL) BM was developed by combining electrospinning and emulsion templating techniques. First, a 250 µm thick polymerised high internal phase emulsion (polyHIPE) made of photocurable PCL was manufactured and treated with air plasma, which was shown to enhance the cellular infiltration. Then, four solvent compositions were investigated to find the best composition for electrospinning a nanofibrous PCL barrier layer on PCL polyHIPE. The biocompatibility and the barrier properties of the electrospun layer were demonstrated over four weeks in vitro by histological staining. Following in vitro assessment of cell viability and cell migration, cell infiltration and the potential of PCL polyHIPE for supporting blood vessel ingrowth were further investigated using an ex-ovo chick chorioallantoic membrane assay. Our results demonstrated that the nanofibrous PCL electrospun layer was capable of limiting cell infiltration for at least four weeks, while PCL polyHIPE supported cell infiltration, calcium and mineral deposition of bone cells, and blood vessel ingrowth through pores.

Analysis of bone formation and membrane resorption in guided bone regeneration using deproteinized bovine bone mineral versus calcium sulfate

Guided Bone Regeneration (GBR) is a technique based on the use of a physical barrier that isolates the region of bone regeneration from adjacent tissues. The objective of this study was to compare GBR, adopting a critical-size defect model in rat calvaria and using collagen membrane separately combined with two filling materials, each having different resorption rates. A circular defect 8 mm in diameter was made in the calvaria of Wistar rats. The defects were then filled with calcium sulfate (CaS group) or deproteinized bovine bone mineral (DBBM group) and covered by resorbable collagen membrane. The animals were killed 15, 30, 45 and 60 days after the surgical procedure. Samples were collected, fixed in 4% paraformaldehyde and processed for paraffin embedding. The resultant sections were stained with H&E for histological and histomorphometric study. For the histomorphometric study, the area of membrane was quantified along with the amount of bone formed in the region of the membrane. Calcium sulfate was reabsorbed more rapidly compared to DBBM. The CaS group had the highest percentages of remaining membrane at 15, 30, 45 and 60 days, compared to the DBBM group. The DBBM group had the highest amount of new bone at 45 and 60 days compared to the CaS group. Based on these results, it was concluded that the type of filling material may influence both the resorption of collagen membrane and amount of bone formed.

Evaluation of the Safety and Efficacy of Soft Tissue Augmentation With a Compressive-Resistant Collagen Matrix in a Nonhuman Primate Model

PURPOSE

The purpose of the present study was to evaluate the safety and efficacy of the compression-resistant collagen-based cross-linked matrix for augmentation of maxillary and mandibular soft tissue defects in an animal model.

MATERIALS AND METHODS

Six rhesus macaque monkeys were subjected to soft tissue grafting in 4 sites intraorally; the anterior maxilla was subjected to hard and soft tissue grafting with implant placement. Each site was randomly assigned 1 of 3 treatments: a compressive-resistant collagen matrix membrane (CM), a subepithelial connective tissue autograft (SCTG), or sham treatment, in which a partial-thickness flap was elevated and then sutured closed with no further treatment (control). The following methods were used for data collection: in vivo evaluation by periodontal probing, ultrasound, shear modulus elasticity, polyether impressions for volumetric analysis, and in vitro analysis by histologic biopsy examinations. In vitro analysis provided by histologic measurements and evaluations was performed on nondecalcified sections. The follow-up period was 6 months.

RESULTS

The SCTG and CM showed favorable tissue integration. No adverse reaction to or deviation from the normal healing processes was detected. The CM integrated well in all sites, with a variable range of soft tissue volume increases. Volumetric discrepancies were appreciated in the histologic analyses and differences were found when the CM and SCTG were applied in the anterior maxilla in combination with hard tissue grafting and implant placement. Histologic evaluation showed favorable integration, no immunogenic response to the CM, and stable volumetric retention in autograft and CM sites during the experimental period.

CONCLUSION

The compressive-resistant CM could be a safe and efficacious alternative for soft tissue augmentation by obviating a donor site and the consequent morbidity. Although a similar performance between the CM and SCTG was observed, further studies will be necessary to estimate the clinical potentiality and describe the limits of the technique.

Recent developments of functional scaffolds for craniomaxillofacial bone tissue engineering applications

Autogenous bone grafting remains a gold standard for the reconstruction critical-sized bone defects in the craniomaxillofacial region. Nevertheless, this graft procedure has several disadvantages such as restricted availability, donor-site morbidity, and limitations in regard to fully restoring the complicated three-dimensional structures in the craniomaxillofacial bone. The ultimate goal of craniomaxillofacial bone reconstruction is the regeneration of the physiological bone that simultaneously fulfills both morphological and functional restorations. Developments of tissue engineering in the last two decades have brought such a goal closer to reality. In bone tissue engineering, the scaffolds are fundamental, elemental and mesenchymal stem cells/osteoprogenitor cells and bioactive factors. A variety of scaffolds have been developed and used as spacemakers, biodegradable bone substitutes for transplanting to the new bone, matrices of drug delivery system, or supporting structures enhancing adhesion, proliferation, and matrix production of seeded cells according to the circumstances of the bone defects. However, scaffolds to be clinically completely satisfied have not been developed yet. Development of more functional scaffolds is required to be applied widely to cranio-maxillofacial bone defects. This paper reviews recent trends of scaffolds for crania-maxillofacial bone tissue engineering, including our studies.

Polyanionic collagen membranes for guided tissue regeneration: Effect of progressive glutaraldehyde cross-linking on biocompatibility and degradation

The ultimate goal of periodontal therapy is to control periodontal tissue inflammation and to produce predictable regeneration of that part of the periodontium which has been lost as a result of periodontal disease. In guided tissue regeneration membranes function as mechanical barriers, excluding the epithelium and gingival corium from the root surface and allowing regeneration by periodontal ligament cells. This report aims to study the effect of glutaraldehyde (GA) cross-linking on mineralized polyanionic collagen (PAC) membranes by conducting a histological evaluation of the tissue response (biocompatibility) and by assessing the biodegradation of subcutaneous membrane implants in rats. We studied six different samples: a PAC, a PAC mineralized by alternate soaking processes for either 25 or 75 cycles (PAC 25 and PAC 75, respectively) and these films cross-linked by GA. Inflammatory infiltrate, cytokine dosage, fibrosis capsule thickness, metalloproteinase immunohistochemistry and membrane biodegradation after 1, 7, 15 and 30 days were measured. The inflammatory response was found to be more intense in membranes without cross-linking, while the fibrosis capsules became thicker in cross-linked membranes after 30 days. The membranes without cross-linking suffered intense biodegradation, while the membranes with cross-linking remained intact after 30 days. The cross-linking with GA reduced the inflammatory response and prevented degradation of the membranes over the entire course of the observation period. These membranes are thus an attractive option when the production of new bone depends on the prolonged presence of a mechanical barrier.

Regeneration of periodontal tissues: guided tissue regeneration

The concept that only fibroblasts from the periodontal ligament or undifferentiated mesenchymal cells have the potential to re-create the original periodontal attachment has been long recognized. Based on this concept, guided tissue regeneration has been applied with variable success to regenerate periodontal defects. Quantitative analysis of clinical outcomes after guided tissue regeneration suggests that this therapy is a successful and predictable procedure to treat narrow intrabony defects and class II mandibular furcations, but offers limited benefits in the treatment of other types of periodontal defects.

Comparison of two resorbable membrane systems in bone regeneration after removal of wisdom teeth: a randomized-controlled clinical pilot study

OBJECTIVES

To compare the performance and safety of Inion GTR(TM) Biodegradable Membrane System and Geistlich resorbable bilayer Bio-Gide((R)) membrane in human bone regeneration.

MATERIAL AND METHODS

In a multicenter, split blind, comparative, randomized, prospective, pilot study 15 patients have been randomized at surgery whether to be treated either with Inion GTR(TM) Biodegradable Membrane System on one and Geistlich resorbable bilayer Bio-Gide((R)) membrane on the other side or vice versa after surgical removal of both fully impacted wisdom teeth. During the follow-up visits at week 1, 2 and 6 and at months 3 and 6 the general state, the wound, eventual adverse events and the medication of the patients were assessed. Computed Tomography (CT) scans were performed immediately and 3 months after the surgery, before biopsy collection. Semi-quantitative histological evaluation and histomorphometric analyses were performed according to the ISO 10993-6 standard. New bone formation and membrane integration were evaluated by CT scan measurements. Tissue healing was evaluated clinically and by photographs between the time on teeth extraction and during follow ups.

RESULTS

Five patients were smokers, none drank alcohol. Mild adverse events like wound infection, haematoma or late swelling of the gums occurred in three patients. The trephine bur harvest of bone biopsies under local anaesthesia was uneventful. Whereas specimens from the sites treated with the Inion membrane yielded 17.0% (SD 24%), the Bio-Gide membrane sites yielded 13.5% (SD 15%) of bone tissue density. In sites treated with the Inion membrane, 9.5% of old bone density and 7.5% of newly formed bone could be found, whereas the Bio-Gide((R)) membrane sites showed 3.8% of old bone density and 9.8% of newly formed bone. There were no statistically significant differences between the two groups with respect to the two variables. The osteoid rim was more extended with the Bio-Gide((R)) (6.6 mm) than with the Inion membrane (5.1 mm) but the difference between the two treatments did not reach statistical significance. Highly significant reductions in the area of the defect with both membranes were detected with significant increases in CT density at the immediate inferio-buccal adjacent bone and in the surgical defect area with both membranes. However, there was neither significant change in CT density in the immediate inferior-lingual adjacent bone of the two membranes, nor significant difference between the membranes on any of the four measurements (area of defect: P=0.1354; CT density immediate inferio-buccal adjacent bone: P=0.7615; CT density surgical defect area: P=0.1876; CT density immediate inferio-lingual adjacent bone: P=0.4212).

CONCLUSION

The overall clinical outcome was satisfying and the majority of the patients showed an uneventful healing phase. Both membranes presented similar capacities regarding their barrier function and were associated with analogous bone regeneration. No statistically valid evidence about the superiority of one particular membrane was obtained. For the patient the only difference is that one product is animal derived and the other synthetic.

Effect of two different bioabsorbable collagen membranes on guided bone regeneration: a comparative histomorphometric study in the dog mandible

BACKGROUND

This study compared bone regeneration following guided bone regeneration with two bioabsorbable collagen membranes in saddle-type bone defects in dog mandibles.

METHODS

Three standardized defects were created, filled with bone chips and deproteinized bovine bone mineral (DBBM), and covered by three different methods: control = no membrane; test 1 = collagen membrane; and test 2 = cross-linked collagen membrane (CCM). Each side of the mandible was allocated to one of two healing periods (8 or 16 weeks). The histomorphometric analysis assessed the percentage of bone, soft tissue, and DBBM in the regenerate; the absolute area in square millimeters of the bone regenerate; and the distance in millimeters from the bottom of the defect to the highest point of the regenerate.

RESULTS

In the 8-week healing group, two dehiscences occurred with CCM. After 8 weeks, all treatment modalities showed no significant differences in the percentage of bone regenerate. After 16 weeks, the percentage of bone had increased for all treatment modalities without significant differences. For all groups, the defect fill height increased between weeks 8 and 16. The CCM group showed a statistically significant (P = 0.0202) increase over time and the highest value of all treatment modalities after 16 weeks of healing,

CONCLUSIONS

The CCM showed a limited beneficial effect on bone regeneration in membrane-protected defects in dog mandibles when healing was uneventful. The observed premature membrane exposures resulted in severely compromised amounts of bone regenerate. This increased complication rate with CCM requires a more detailed preclinical and clinical examination before any clinical recommendations can be made.

Angiogenesis pattern of native and cross-linked collagen membranes: an immunohistochemical study in the rat

The aim of the present study was to immunohistochemically evaluate angiogenesis pattern of native and cross-linked collagen membranes after subcutaneous implantation in rats. Five commercially available and three experimental membranes (VN) were included: (1) BioGide (BG), (2) BioMend (BM), (3) BioMend Extend (BME), (4) Ossix (OS), (5) TutoDent (TD), and (6-8) VN(1-3). Specimens were randomly allocated in unconnected subcutaneous pouches (n=4) separated surgically on the back of 40 wistar rats, which were divided into five groups (2, 4, 8, 16, and 24 weeks), including eight animals each. Pattern of angiogenesis was labelled using primary mouse monoclonal antibody to transglutaminase II. For each membrane, the period of time, needed for a complete and homogeneous transmembraneous vascularization, was assessed immunohistomorhometrically. Differences between the membranes were found regarding the initial pattern of transmembraneous angiogenesis, as evaluated 2 weeks following implantation. Mean cross- and longitudinal-sectional area of blood vessels (%) was highest for VN(3) (5.27+/-2.73), followed by BG (2.45+/-0.88), VN(1) (2.07+/-0.29), VN(2) (1.91+/-0.55), TD (1.44+/-0.53), BME (0.35+/-0.29) and BM (0.25+/-0.4). In contrast to BG and VN(1-3), BM, BME and TD exhibited a homogeneous transmembraneous formation of blood vessels merely 4-8 weeks following implantation. OS, however, exhibited no signs of angiogenesis throughout the whole study period. Within the limits of the present study, it may be concluded that pattern of transmembraneous angiogenesis markedly differs among the membranes investigated.

Management of a root fracture in an immature permanent tooth

A 9-year-old girl with trauma to the maxillary right permanent central incisor is reported. Clinically the tooth appeared extruded with one third of the root visible. The radiographic examination revealed a root fracture. The extruded tooth was repositioned and splinted with a heavy wire and adhesive resin, after which a resorbable collagen tissue was placed to cover the buccal region. Subsequent to the injury, swelling was observed and the patient complained of pressure pain in the periapical region of the tooth with no response to electric pulp testing. It was treated successfully with periodontal therapy and endodontic therapy with Vitapex.

Biodegradation of differently cross-linked collagen membranes: an experimental study in the rat

The aim of the present study was to compare the biodegradation of differently cross-linked collagen membranes in rats. Five commercially available and three experimental membranes (VN) were included: (1) BioGide (BG) (non-cross-linked porcine type I and III collagens), (2) BioMend (BM), (3) BioMendExtend (BME) (glutaraldehyde cross-linked bovine type I collagen), (4) Ossix (OS) (enzymatic-cross-linked bovine type I collagen), (5) TutoDent (TD) (non-cross-linked bovine type I collagen, and (6-8) VN(1-3) (chemical cross-linked porcine type I and III collagens). Specimens were randomly allocated in unconnected subcutaneous pouches separated surgically on the back of 40 wistar rats, which were divided into five groups (2, 4, 8, 16, and 24 weeks), including eight animals each. After 2, 4, 8, 16, and 24 weeks of healing, the rats were sacrificed and explanted specimens were prepared for histologic and histometric analysis. The following parameters were evaluated: biodegradation over time, vascularization, tissue integration, and foreign body reaction. Highest vascularization and tissue integration was noted for BG followed by BM, BME, and VN(1); TD, VN(2), and VN(3) showed prolongated, while OS exhibited no vascularization. Subsequently, biodegradation of BG, BM, BME and VN(1) was faster than TD, VN(2), and VN(3). OS showed only a minute amount of superficial biodegradation 24 weeks following implantation. Biodegradation of TD, BM, BME, VN(2), and VN(3) was associated with the presence of inflammatory cells. Within the limits of the present study, it was concluded that cross-linking of bovine and porcine-derived collagen types I and III was associated with (i) prolonged biodegradation, (ii) decreased tissue integration and vascularization, and (iii) in case of TD, BM, BME, VN(2), and VN(3) foreign body reactions.

Biocompatibility of various collagen membranes in cultures of human PDL fibroblasts and human osteoblast-like cells

The aim of the present study was to evaluate the biocompatibility of differently cross-linked collagen membranes in cultures of human PDL fibroblasts and human osteoblast-like cells. Four collagen membranes [BioGide (BG), BioMend (BM), Ossix (OS) and TutoDent (TD)] were tested. Cells plated on culture dishes (CD) served as positive controls. Six specimens of each membrane were incubated with (1) human PDL fibroblasts [2 x 10(4) cells] (n=24), and (2) human osteoblast-like cells (SaOs-2) [2 x 10(4) cells] (n=24) under standardized conditions. After 7 days, adherent cells were stained with hematoxylin and counted using a reflected light microscope and the cell density per square millimeter was calculated. Additionally, cell morphology was investigated using scanning electron microscopy (SEM). Cell counts were presented as means and standard deviations (cells/mm(2)) and analyzed for statistical difference using the Wilcoxon test: (1) CD (434+/-76)>BG (64+/-19)=OS (61+/-8)>TD (44+/-4)>BM (12+/-5); (2) CD (453+/-92)>BG (94+/-46)=TD (84+/-49)>OS (41+/-23)>BM (0). SEM examination revealed that PDL fibroblasts adherent on BG, TD and OS appeared spindle-shaped and flat, like cells on CD. SaOs-2 osteoblasts adherent on CD were star shaped and flat, but mostly round in shape on BG, OS and TD. BM appeared to be incompatible with the attachment and proliferation of SaOs-2 cells; however, a few PDL fibroblasts were found in a round shape. Within the limits of the present study, it was concluded that (i) BG, TD and OS promoted, and (ii) BM inhibited the attachment and proliferation of human PDL fibroblasts and human SaOs-2 osteoblasts.

Collagen membrane resorption in dogs: a comparative study

Guided tissue barriers using materials such as collagen are used in the hope of excluding epithelium and the gingival corium from the root surface or alveolar bone to facilitate regeneration. Convention suggests that the longer a membrane remains intact, the better the regeneration results. The purpose of this study was to determine the resorption rates of various collagen membranes in the oral cavity of dogs. Twelve adult mongrel dogs had three different collagen membranes (BioGide, AlloDerm porcine-derived, and AlloDerm human-derived) randomly inserted and secured into surgical pouches made in their palates. Full-thickness tissue punch biopsy specimens taken at 1, 2, 3, or 4 months after surgery were evaluated histologically for membrane intactness and other associated changes. At 1 month, all membranes had slight to moderate degradation. At 2 months, all membranes had moderate to severe degradation with the exception of one AlloDerm human-derived membrane that was intact. At 3 months, all membranes had severe degradation to not identifiable. At 4 months, all membranes had severe degradation to completely absent. Blood vessel penetration varied from none to moderate. Inflammation was found in only two samples. In the dog, all three tested collagen membranes showed slight to moderate degradation at 1 month and were severely degraded to completely absent at 4 months. Within the limits of transferring animal data to humans, clinicians need to be aware of these resorption rates when selecting membranes for guided tissue and bone regeneration.

Collagen membranes: a review

Collagen materials have been utilized in medicine and dentistry because of their proven biocompatability and capability of promoting wound healing. For guided tissue regeneration (GTR) procedures, collagen membranes have been shown to be comparable to non-absorbable membranes with regard to probing depth reduction, clinical attachment gain, and percent of bone fill. Although these membranes are absorbable, collagen membranes have been demonstrated to prevent epithelial down-growth along the root surfaces during the early phase of wound healing. The use of grafting material in combination with collagen membranes seems to improve clinical outcomes for furcation, but not intrabony, defects when compared to the use of membranes alone. Recently, collagen materials have also been applied in guided bone regeneration (GBR) and root coverage procedures with comparable success rates to non-absorbable expanded polytetrafluoroethylene (ePTFE) membranes and conventional subepithelial connective tissue grafts, respectively. Long-term clinical trials are still needed to further evaluate the benefits of collagen membranes in periodontal and peri-implant defects. This article will review the rationale for each indication and its related literature, both in vitro and in vivo studies. The properties that make collagen membranes attractive for use in regenerative therapy will be addressed. In addition, varieties of cross-linking techniques utilized to retard the degradation rate of collagen membranes will be discussed.

Effect of two delivery systems for recombinant human bone morphogenetic protein-2 on periodontal regeneration in vivo

Resorbable collagen membranes for guided tissue regeneration in periodontal therapy have shown promise but are not osteoinductive. As recombinant human bone morphogenetic protein-2 (rhBMP-2) is known to have an affinity for collagen, the use of this osteoinductive agent incorporated into a collagen vehicle may act as a suitable carrier to promote periodontal regeneration. The aim of this study was to investigate the effects of two different collagen delivery systems for rhBMP-2 in rat periodontal fenestration defects. Using the collagen membrane delivery system, 3 groups of adult Wistar rats which had surgical defects created on the right side of the mandible involving the removal of bone and exposure of the molar roots were treated with either rhBMP-2 in colagen membrane (BMPm) (n = 12 animals), or collagen membrane only (COLm) (n = 12), or were left untreated (UN) (n = 14). Using the collagen gel delivery system, surgical defects were treated with either rhBMP-2 incorporated in a collagen gel carrier (BMPg) (n = 5) or had collagen gel only (COLg) (n = 6). Animals were killed 10 d postoperatively and tissues processed for histology. New bone formation was significantly greater in BMPg compared with both BMPm and controls (p < 0.05). However, new cementum formation was significantly greater in BMPm (721 +/- 166 micron2, mean +/- SE) compared with COLm, COLg and UN (p < 0.02) (190 +/- 44 micron2, 327 +/- 114 micron2 and 172 +/- 33 micron2, respectively) and more than 1.5 times BMPg (451 +/- 158 micron2). In conclusion, both carrier systems for rhBMP-2 significantly increased new bone formation compared with controls during the early stages of periodontal wound healing. However, the more slowly dissolving collagen membrane carrier system for rhBMP-2 produced significantly greater new cementum compared with the collagen gel carrier, suggesting that a more prolonged exposure of rhBMP-2 is required to increased cementogenesis.

Clinical comparison of resorbable and non-resorbable barriers for guided periodontal tissue regeneration

The purpose of this study was to compare the clinical results of guided periodontal tissue regeneration (GPTR) using a resorbable barrier manufactured from a copolymer of polylactic and polyglycolic acids (Resolut Regenerative Material) with those of non-resorbable e-PTFE barrier (Gore-Tex Periodontal Material). 12 subjects participated, 6 with similarly paired class II furcations and 6 with 2 similar 2, 3-wall periodontal lesions. The resorbable and non-resorbable barriers were randomly assigned to 1 defect in each subject. Non-resorbable barriers were removed in six weeks. Plaque index (PlI), gingival index (GI), probing depth (PD), clinical attachment level (CAL) and gingival recession (R) were recorded at baseline, (i.e., immediately prior to surgery) and at 12 months postsurgically. The clinical healing was similar and uneventful in both groups. Intrabony pockets depicted significant changes from baseline (p < 0.05) for probing depth reduction and gain in clinical attachment levels. No differences were found between treatments. Class II furcations showed significant improvements from baseline (p < or = 0.05) for probing depth reduction and clinical attachment gain. No differences were detected between treatments. It is concluded that the resorbable barrier tested is as effective as the nonresorbable e-PTFE barrier for the treatment of class II furcations and intrabony defects.

Resorption rates of 2 commercially available bioresorbable membranes. A histomorphometric study in a rabbit model

The respective resorption rates of recently commercialized collagen versus polylactic acid-citric acid ester membranes were compared. 16 rabbits were implanted with 2 mm x 4 mm pieces of membrane of both types in the alveolar mucosa just apically to the incisors on either side of the mouth. 1 animal was sacrificed on day 0, just after the operation. The others were sacrificed at 1, 2, 3, 5, 7, 9 and 12 weeks. The specimens were prepared for histologic examination. Observations showed that the cross-linked collagen membranes induced severe inflammation and were resorbed within 2 weeks. The polylactic acid-citric acid ester polymer barriers produced a much more moderate infiltrate and were still not totally resorbed at 12 weeks. Although resorption rates in the rabbit may not be similar to those observed in humans, it seems that the durability of the polymer barrier is more adequate for guided tissue regeneration than the cross-linked collagen.

A prospective multi-center study evaluating periodontal regeneration for Class II furcation invasions and intrabony defects after treatment with a bioabsorbable barrier membrane: 1-year results

The purpose of this prospective multi-center study was to evaluate a resorbable barrier membrane designed for periodontal regeneration. Thirty-one Class II furcations and 30 two- and three-wall intrabony defects were treated by flap debridement and bioabsorbable barrier membrane augmentation. The efficacy of treatment was evaluated in terms of changes in vertical probing depth (PD), horizontal probing depth (HPD), clinical attachment levels (CAL), and recession. Five centers participated in the study. Changes in clinical parameters are reported by individual center and by the average of the centers. All patients had either one molar with a Class II furcation or an intrabony defect. Baseline data were taken on the day of surgery. Post-treatment data were collected at 6 months and 1 year. This report is based on the 1-year findings. The average initial PD for Class II furcations was 6.1 mm. At 1 year the average PD was reduced to 3.6 mm, a 2.5 mm change. These differences were clinically and statistically significant (P < 0.0001). There was an average gain of 2.1 mm of clinical attachment (P < 0.0001) and 0.4 mm of recession (P < 0.04). There was a mean of 1.8 mm change in HPD (P < 0.0001). For intrabony defects, at 1 year there was an average PD reduction of 4.1 mm (P < 0.0001) and a mean gain of CAL of 2.9 mm (P < 0.0001). At 1 year the average recession was 0.9 mm which was statistically significant. When treatment outcomes were compared between centers there were no differences for either group of treated defects. There were differences between centers when baseline PD for furcations and intrabony sites were compared. The results of this study indicate that clinically and statistically significant improvements in PD, CAL, and HPD occurred after treatment of Class II furcations and 2- to 3-wall intrabony defects with the bioabsorbable periodontal membrane.

Treatment of intrabony defects with collagen membrane barriers. Case reports

Two separate investigations were undertaken to assess the clinical characteristics and the safety, and to determine whether an absorbable type 1 bovine collagen barrier membrane would result in the improvement of clinical parameters during guided tissue regeneration in humans. The collagen membrane barrier was placed over a total of 21 interdental intrabony periodontal defects in 18 patients. The surgical procedures and postsurgical regimen were similar in both components of the investigation. Sulcular incisions were used and the sites were surgically exposed by reflection of full thickness mucoperiosteal flaps. The intrabony defects were debrided and the root surfaces prepared with automatic scalers and curets. Four 1-minute applications of tetracycline HCl 50 mg/ml were applied to the root surface. The collagen membrane barrier was hydrated in sterile saline until pliable, then trimmed so it covered the osseous defect and extended 2 to 3 mm beyond the defect. In both investigations, the collagen barrier membrane was not sutured, but retained by "pouching" or undermining the flap. Healing occurred without complications. There were no untoward or adverse reactions to the material in either phase of the study. In the initial investigation, 13 intrabony defects with probing depths of > or = 5 mm were treated in 9 patients having a mean age of 50.6 years. No controls defects were treated. Soft and hard tissue measurements were taken at the time of initial surgery and at 2, 4, and 6 months. In the second phase, 9 patients were enrolled with a mean age of 49.7 years. They had similar bilateral interdental intrabony defects with probing depths > or = 6 mm. One defect received the collagen membrane barrier, while the other was treated by flap debridement alone. The collagen membrane had undergone modification since the initial investigation, and was more highly cross-linked to retard absorption. After initial therapy, and prior to the surgical procedure, a series of 3 dermal patch tests were used to determine whether the patient would elicit a reaction to the collagen. Venous blood was drawn at baseline, 7 to 10 days, 18 to 21 days and at 8 weeks for analysis by ELISA for comparison of test and control sites relative to baseline. There were no allergic response to the dermal tests, and the ELISA tests indicated no significant differences between test and control sites. An automated probe was used to record soft and hard tissue measurements. These included the probing depths and clinical attachment levels.(ABSTRACT TRUNCATED AT 400 WORDS)

A comparative clinical study: the use of human type I collagen with and without the addition of metronidazole in the GTR method of treatment of periodontal disease

This investigation was undertaken to evaluate cross-linked human type I collagen, with and without added metronidazole, when used as a barrier membrane in the guided tissue regeneration (GTR) principle of treatment for periodontal disease. 16 patients suffering from moderate to severe periodontitis with 78 bilaterally matched periodontal defects underwent similar contralateral surgical flap procedures after preliminary scaling, polishing and oral hygiene instruction. At the experimental sites, which were selected at random, the flap was closed over metronidazole impregnated collagen as a GTR membrane, the contralateral sites receiving a plain collagen barrier as control. The plaque index (PLI), gingival index (GI), bleeding index (BI), probing pocket depth (PPD) and probing attachment level (PAL) were recorded at baseline, 6, 12 and 26 weeks post-operatively. The bony defects were classified and furcation involvement noted. The clinical parameters were recorded by an examiner, other than the surgeon, who had been previously assessed for accurate reproducibility of measurements and was unaware of the experimental sites. PPD and PAL were measured with a constant pressure probe, localised by a soft stent. Post-operative discomfort was evaluated by means of a questionnaire. PLI, GI and BI were significantly improved compared to baseline for both test and control sites at 6, 12 and 26 weeks post surgery (p < 0.001) but there was no significant difference between these sites (p > 0.05). There was a reduction in PPD at 6 weeks which was significant at 12 and 26 weeks post-operatively (p < 0.001) for both test and control sites, but no difference between these sites was evident (p > 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Guided tissue regeneration: comparison of bioabsorbable and non-bioabsorbable membranes. Histologic and histometric study in dogs

This study examined histologic and histometric responses to 2 bioabsorbable membranes made from a synthetic copolymer of glycolide and lactide. They were tested for their biocompatibility, resorption characteristics, and ability to support periodontal regeneration. Expanded polytetrafluoroethylene (ePTFE) was used as control. Nine fox hound dogs with no periodontal disease were used. They were sedated and their teeth thoroughly scaled and root planed. Plaque control was maintained. Two weeks later, each dog was anesthetized using gas anesthesia. Buccal and lingual mucoperiosteal flaps were reflected in the mandibular premolar areas. Randomly selected, buccal alveolar bone was reduced on the 2nd and 4th premolars to a level 5 to 8 mm apical to the cemento-enamel junction creating a Class II buccal furcation defect on one quadrant, while the other quadrant received a Class II buccal defect only on the 4th premolar. Root surfaces were denuded of periodontal ligament and cementum, and notches were placed at the bone level of each root. In one quadrant, one site received Type I membrane and the other site received Type II. The contralateral quadrant received ePTFE. Flaps were positioned slightly coronally and sutured. Sutures were removed 1 week later. One month after surgery, 3 dogs were sacrificed and ePTFE barriers were removed from the remaining 6 dogs. Of these, 3 were sacrificed 3 months after surgery and the other 3 at 6 months. Undemineralized experimental tissues were embedded in methylmethacrylate and 8 to 10 microns thick sections were cut in a bucco-lingual direction throughout the mesiodistal extension of the tooth.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of a collagen matrix on healing in periodontal fenestration defects in dogs

Contralateral periodontal fenestration defects in seven beagle dogs were used to evaluate influence of a collagen matrix on periodontal wound healing. The defects (6 x 4 mm) were created through the buccal cortical plates of the maxillary canine teeth following elevation of mucoperiosteal flaps. The collagen was fitted to the defects on one side. Contralateral defects served as controls. Flaps were repositioned and sutured. Dogs were sacrificed 4 weeks after surgery and block sections including teeth and surrounding structures were prepared for histometric analysis. No meaningful differences in cementum and bone regeneration were observed between treatments. There was seemingly more bone regeneration in the apical than in the coronal aspect of the defects and significantly more cementum regeneration. Root resorption was observed in one collagen and one control defect. Ankylosis was not observed. The results suggest that the maxillary canine periodontal fenestration defect can be used as a model to evaluate factors that may enhance cementum and bone regeneration. The collagen matrix neither enhanced nor inhibited periodontal wound healing in this model.

Report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The growth in the dental literature continues to escalate, as evidenced by the publication of at least 326 new books in 1988 and 1989 and more than 20 new journals in 1989. There still appears to be undue emphasis on quantity instead of quality of research. This proliferation in the literature poses ever increasing difficulties to this Committee in filtering out the articles that are of particular interest to the members of the Academy and identifying those that are most likely to have a major impact on dental practice and service. The subjects covered include periodontics, caries and preventive dentistry, craniomandibular disorders, occlusion, pulp biology, ceramics, and restorative dental materials.