Porcine-derived Collagen Matrix Research Articles

A prospective case series on the efficacy of a cross-linked collagen matrix to increase buccal soft tissue thickness at large edentulous gaps: One-year results.

The objective of this study is to assess profilometric changes following soft tissue augmentation with a cross-linked porcine-derived collagen matrix (CMX) at large edentulous gaps of at least two units. Systemically healthy, nonsmoking patients with a large edentulous gap of at least two units demonstrating a horizontal soft tissue defect, were enrolled in a prospective case series. Soft tissue augmentation was performed in a one-stage approach with a 6 mm thick CMX at the time of implant placement. The primary outcome was the change in buccal soft tissue profile (BSP) at a mesial, central, and distal area of interest (AOI) up to 1 year when compared to the preoperative situation based on superimposed digital surface models. Secondary outcomes included the horizontal dimension of the soft tissue defect, complications, and marginal bone loss (MBL). Fifteen patients (eight females; mean age 58.73 years) were enrolled and 13 could be re-assessed at 1-year follow-up. The mean linear increase in BSP at 1 year was 0.66 mm (98.3% CI: 0.37-0.94), 0.80 mm (98.3% CI: 0.39-1.22), and 0.69 mm (98.3% CI: 0.32-1.06) at the mesial, central, and distal AOI, respectively. Substantial shrinkage of about 75% was observed in all areas between augmentation and 1-year follow-up. Even though 11 of 13 sites were fully augmented immediately postoperative, a soft tissue defect recurred in all sites at 1-year follow-up with a mean deficit of 2.30 mm. Altogether, 25% of the original soft tissue defect was eliminated by soft tissue augmentation. CMX was safe since no postoperative complications occurred and MBL was limited (0.70 mm). CMX is efficacious for horizontal soft tissue augmentation at large edentulous gaps. However, considerable graft resorption may be expected, and the clinical relevance of the augmentation may be questionable since all patients demonstrated a recurring and considerable soft tissue defect 1 year after surgery.

A Multi-Centre Randomized Controlled Trial Comparing Connective Tissue Graft with Collagen Matrix to Increase Buccal Soft Tissue Thickness: A Cone-Beam CT Analysis.

(1) Aim: a cross-linked porcine-derived collagen matrix (CMX) has been developed for soft tissue augmentation. Although this grafting material does not require a second surgical site, recent findings have indicated deeper pockets, more marginal bone loss and more midfacial recession in the short term when compared to connective tissue graft (CTG). Hence, the aim of the present study was to evaluate the safety of CMX based on buccal bone loss over a one-year period. (2) Methods: Patients who were missing a single tooth in the anterior maxilla were included, in whom the failing tooth had been removed at least 3 months prior and who presented a horizontal mucosa defect. All sites had a bucco-palatal bone dimension of at least 6 mm as assessed on Cone-Beam Computed Tomography (CBCT) to ensure complete embedding of an implant by bone. All patients received a single implant and an immediate implant restoration using a full digital workflow. Sites were randomly allocated to the control (CTG) or test group (CMX) to increase buccal soft tissue thickness. All surgeries were performed by means of full thickness mucoperiosteal flap elevation, placing CTG and CMX in contact with the buccal bone wall. Safety was assessed by evaluating the impact of CTG and CMX on buccal bone loss over a one-year period using superimposed CBCT scans. (3) Results: thirty patients were included per group (control: 50% females, mean age 50; test: 53% females, mean age 48) and 51 (control: 25; test: 26) could be analyzed for buccal bone loss. At 1 mm apical to the implant-abutment interface (IAI), most horizontal resorption was found pointing to 0.44 mm in the control group and 0.59 mm in the test group. The difference of 0.14 mm (95% CI: -0.17-0.46) was not statistically significant (p = 0.366). At 3 mm and 5 mm apical to the IAI, the difference between the groups was 0.18 mm (95% CI: -0.05-0.40; p = 0.128) and 0.02 mm (95% CI: -0.24-0.28; p = 0.899), respectively. Vertical buccal bone loss amounted to 1.12 mm in the control group and 1.14 mm in the test group. The difference of 0.02 mm (95% CI: -0.53-0.49) was not statistically significant (p = 0.926). (4) Conclusions: In the short term, soft tissue augmentation with CTG or CMX results in limited buccal bone loss. CMX is a safe alternative to CTG. Longer follow-up is needed to assess the impact of soft tissue augmentation on buccal bone.

Flapless Decoronation: A Minimally Invasive Approach

Traumatic injuries to the permanent dentition are most common in children. In severe dentoalveolar injuries, especially avulsion and intrusion, dentoalveolar ankylosis is a common complication, leading to adverse effects on the developing alveolar bone and interfering with the eruption of the adjacent teeth. The decoronation procedure was suggested in 1984 to reduce these side effects related to ankylosis. The objective of the current publication is to describe a minimally invasive, flapless decoronation procedure aimed to minimize and simplify the surgical procedure of decoronation, and ease its clinical acceptance, particularly in young children. The technique is described in a detailed protocol and demonstrated in two cases. Under local anesthesia, the dental crown is removed, and the root is reduced by 1.5-2.0 mm apically to the marginal bone crest. The root canal content is then removed, allowing it to fill with blood. The socket is coronally sealed with a porcine-derived collagen matrix (PDCM) sutured using the "parachute" technique over the resected root, allowing close adaptation to the surrounding soft tissue. In conclusion, the presented technique of flapless decoronation is a modification of the classic decoronation procedure, which can be used as a minimally invasive technique to simplify the surgical procedure and the post-operative process.

Connective tissue graft vs porcine collagen matrix after immediate implant placement in esthetic area: A randomized clinical trial.

The use of connective tissue graft (CTG) with immediate implant placement and provisionalisation have shown promising results. It is not clear if the same outcome could be achieved using porcine-derived collagen matrix (PDCM) as grafting material. This study aimed to assess the esthetic and functional outcomes of immediate temporization of immediately placed fully tapered implants combined with bone and soft tissue augmentation, using either a CTG or a PDCM, in fresh extraction sockets of the anterior sites. Patients with a failing anterior tooth were included in this study. After extraction, they received an immediate implant with simultaneous hard and soft tissue augmentation and immediate provisional restoration. Patients were randomly assigned to one of the group. Soft tissue augmentation in the control group (CTG) consisted of a CTG, whereas PDCM was used in the test group. After 4 months, definitive restorations were delivered, and pink esthetic score (PES) was evaluated at T1, prosthetic delivery, and at 12-month follow-up (T2). In addition, crestal bone change, probing depth, bleeding on probing, plaque index, bleeding on provisional removal, and implant stability quotient were also recorded. A total of 45 patients received the intended treatment (22 controls and 23 tests) 45 implants totally, with no implant failures at T2. PES mean ± SD after 1 year was noted to be 12.9 ± 1.2 for the CTG group and 12.1 ± 1.3 for the PDCM group (p=0.507). Within the limits of this trial, both treatment protocols resulted in comparable esthetic outcomes, with results showing PES >12 and stable clinical parameters after 1 year of follow-up.

A 3-Year Prospective Study on a Porcine-Derived Acellular Collagen Matrix to Re-Establish Convexity at the Buccal Aspect of Single Implants in the Molar Area: A Volumetric Analysis.

Background: Xenogeneic soft tissue substitutes are currently being investigated as an alternative to subepithelial connective tissue grafts (CTG) with the intention to avoid postoperative morbidity associated with autologous grafting. The aim of the present study was to volumetrically evaluate the effectiveness and mid-long-term stability of a porcine-derived collagen matrix (PDCM) (Mucoderm®, Botiss gmbh, Berlin, Germany) in increasing soft tissue volume at the buccal aspect of molar implant sites. Methods: Periodontally healthy non-smoking patients with a single tooth gap in the molar area were selected for a prospective case series. All sites had a bucco-oral bone dimension of at least 8 mm and demonstrated a horizontal alveolar defect. A wide diameter implant was placed under the elevated buccal flap and a PDCM was applied. The primary outcome was the linear increase in buccal soft tissue profile (BSP) within a well-defined area of interest. This was performed with designated software (SMOP; Swissmeda AG, Zurich, Switzerland) on the basis of superimposed digitalized study casts taken before surgery (T0), immediately after surgery (T1), at three months (T2), one year (T3) and three years (T4). Secondary outcomes were alveolar process deficiency and clinical parameters. Results: Fourteen out of 15 treated patients attended the three-year re-assessment (four females; mean age 51.4 years). Mean linear increase in BSP at T1 was 1.53 mm (p = 0.001). The PDCM showed substantial resorption at T2 (1.02 mm or 66.7%) (p = 0.001). Thereafter, a 0.66 mm volume gain was observed (p = 0.030), possibly due to the installation of a permanent crown displacing the soft tissues to the buccal aspect. This resulted in a linear increase in BSP of 1.17 mm (76.5%) at T4. Alveolar process deficiency significantly reduced over time (p = 0.004). However, 50% of patients still demonstrated a slight (6/14) or obvious (1/14) alveolar process deficiency at study termination. Implants demonstrated healthy clinical conditions. Conclusions: The PDCM demonstrated marked resorption during the early stages of healing. Due to the matrix thickening the tissues, and the permanent crown displacing the tissues, 76.5% of the initial increase in BSP could be maintained over a three-year period. Half of the patients failed to show perfect soft tissue convexity at the buccal aspect.

In vitro observation of macrophage polarization and gingival fibroblast behavior on three-dimensional xenogeneic collagen matrixes.

Collagen biomaterials are widely used for soft tissue augmentation. Cross-linking techniques for collagen matrix (CM) achieve mechanical and volumetric stability; nevertheless, cross-linking may compromise biocompatibility. The aim of the present study was to investigate two different three-dimensional (3D) porcine-derived CMs, noncross-linked (ncl)_CM and cross-linked (cl)_CM, for their effects on macrophages (Mφ) and gingival fibroblasts. The effects of the CMs on the cell viability, proliferation, and polarization of Mφ derived from human monocyte THP-1 cells were assessed. The effects of paracrine factors from Mφ cultured on the CMs were further studied in human gingival fibroblasts (HGF-1 cells). The spongy layer of ncl_CM was partially resorbed after 1 day of culture. cl_CM maintained increased numbers of viable cells when compared with ncl_CM on day 3 for both THP-1 and HGF-1 cells. Higher mRNA levels of M1 markers, including IL-1 and IL-6, were found in Mφ cultured on cl_CM, while no significant differences were observed in M2 marker expression levels, including Arg1 and CD206, for cells cultured on both CMs when compared with those of the control. Furthermore, the conditioned medium collected from Mφ cultured on both CMs decreased cell viability. Nevertheless, neither of the CM-conditioned media influenced the mRNA levels of TGF-β, COL1a2, and PDGF-A in HGF-1 cells when compared with the control media. A comparison showed that cl_CM tended to result in more viable cells than ncl_CM, while cl_CM polarized Mφ toward an M1 phenotype, which was confirmed by the observation of increased mRNA levels of pro-inflammatory cytokines.

Allografts and Xenografts for Periodontal Plastic Surgical Procedures

The selection of surgical techniques and grafting materials is undoubtedly a critical component in the treatment of gingival recession defects. In order to provide top quality care, dental professionals are always in pursuit of treatment modality that provides maximal efficacy and predictability with minimal patient morbidity. The subepithelial connective tissue graft procedure, the gold standard, has been consistently proven to show excellent root coverage, but limited palatal tissue availability and potential morbidity associated with the harvesting process push dental practitioners to seek an alternative. The same holds true for peri-implant tissues—while autogenous grafts have served our purpose well, alternatives that can achieve similar results while avoiding a second intraoral wound (the donor sites) are preferred. The purpose of this review of recent studies is to evaluate the effectiveness and predictability of allografts and xenografts for root coverage procedures and around dental implants. The electronic database search was limited to the past 5 years and to the studies addressing root coverage procedures in the Miller class I and II gingival recession (even though the 2017 International Workshop suggested a new classification, the majority of research projects use the classic Miller classification). Search was also made for studies addressing soft tissue treatment around implants that were published during the same period. A total of 30 human clinical trials involving allografts (mainly acellular dermal matrix and placental membranes) and xenografts (porcine-derived collagen matrix) for treatment of gingival recession and a total of 19 clinical studies using allografts and xenografts to improve soft tissue quality around implants were selected. Based on the selected studies, acellular dermal matrix in combination with various flap designs appears to produce results similar to autogenous grafts in terms of mean root coverage and width of keratinized tissue. Other grafting materials, while less effective compared to autogenous grafts, still show some promise especially in patient-centered outcomes. For soft tissue quality improvement around implant sites, allografts and xenografts in general provide satisfactory clinical results. Multicenter, randomized clinical studies with large numbers of individuals and long-term outcomes may provide the most realistic answer for this topic.

Clinical and Histologic Evaluations of Porcine-Derived Collagen Matrix Membrane Used for Vertical Soft Tissue Augmentation: A Case Series.

This case series aimed to clinically and histologically evaluate porcine-derived membrane used for vertical thickening of thin soft tissues. Twenty porcine-derived collagen membranes and bone-level implants were placed in 20 patients. After 2 months, thickened soft tissues were measured and biopsy samples were harvested. All xenografts healed successfully. The average thickness of thin soft tissue before vertical thickening was 1.65 ± 0.36 mm, while tissue thickness increased to 3.45 ± 0.52 mm after the procedure (P < .001); the mean thickness increase was 1.8 ± 0.13 mm. Histologic analysis showed complete integration of the graft and no differences (P = .4578) in vascularization between the host (39.74 ± 17.15 vessels/mm2) and graft (30.43 ± 11.26 vessels/mm2). It can be concluded that porcine-derived membrane can be used for vertical soft tissue thickening with substantial gain in tissue height.

Biofunctionalization of porcine-derived collagen matrix using enamel matrix derivative and platelet-rich fibrin: influence on mature endothelial cell characteristics in vitro.

The present study evaluated the effect of an enamel matrix derivative (EMD) and platelet-rich fibrin (PRF)-modified porcine-derived collagen matrix (PDCM) on human umbilical vein endothelial cells (HUVEC) in vitro. PDCM (mucoderm®) was prepared to 6mm (±0.1mm) diameter discs. PDCM samples were incubated with either EMD, PRF, or control solutions for 100min at 4°C before the experiments. Cell-inducing properties of test materials on HUVEC cells were tested with cell proliferation assays (MTT, PrestoBlue®), a cytotoxicity assay (ToxiLight®), a Boyden chamber migration assay, and a cell attachment assay. Scanning electron microscopy (SEM) imaging was performed to determine the surface and the architecture of the modified matrices. Cell proliferation was elevated in the EMD and PRF groups compared with control (p each ≤0.046). PRF modification increased HUVEC migration ability by 8-fold compared with both control and EMD groups (p each <0.001). Both treatments significantly promoted the cell attachment of HUVEC to PDCM, as assessed by direct cell counts on the matrices (p each <0.001). HUVEC cell characteristics were overall improved by EMD- and PRF- modified PDCM. Adsorbed bioactive molecules to the PDCM surface may have contributed to a more preferable environment to surrounding cells. The results may give evidence that PDCM modification with EMD or PRF, respectively, might be a useful approach to improve clinical outcomes, to prevent inflammatory reactions and wound-healing disturbances, and to expand the clinical application area of PDCM.

Efficacy of Mucograft vs Conventional Resorbable Collagen Membranes in Guided Bone Regeneration Around Standardized Calvarial Defects in Rats: A Histologic and Biomechanical Assessment.

Guided bone regeneration (GBR) using a porcine-derived collagen matrix (Mucograft [MG], Geistlich) has not yet been reported. The aim of this histologic and biomechanical study was to compare the efficacy of MG versus resorbable collagen membranes (RCMs) in facilitating GBR around standardized rat calvarial defects. Forty female Wistar albino rats with a mean age and weight of 6 to 9 weeks and 250 to 300 g, respectively, were used. With the rats under general anesthesia, the skin over the calvaria was exposed using a full-thickness flap. A 4.6-mm-diameter standardized calvarial defect was created in the left parietal bone. For treatment, the rats were randomly divided into four groups (n = 10 per group): (1) MG group: the defect was covered with MG; (2) RCM group: the defect was covered with an RCM; (3) MG + bone group: the defect was filled with bone graft particles and covered by MG; and (4) RCM + bone group: the defect was filled with bone graft particles and covered by an RCM. Primary closure was achieved using interrupted resorbable sutures. The animals were sacrificed at 8 weeks after the surgical procedures. Qualitative histologic analysis and biomechanical assessment to identify hardness and elastic modulus of newly formed bone (NFB) were performed. Collected data were statistically analyzed using one-way analysis of variance. Histologic findings revealed NFB with fibrous connective tissue in all groups. The quantity of NFB was highest in the RCM + bone group. Statistically significant differences in the hardness (F = 567.69, dfN = 3, dfD = 36, P < .001) and elastic modulus (F = 294.19, dfN = 3, dfD = 36, P < .001) of NFB were found between the groups. Although the RCM + bone group had the highest mean ± standard deviation (SD) hardness of NFB (531.4 ± 24.9 MPa), the RCM group had the highest mean ± SD elastic modulus of NFB (18.63 ± 1.89 GPa). The present study demonstrated that RCMs are better than MG at enhancing new bone formation in standardized rat calvarial defects when used along with mineralized particulate graft material.

Influence of porcine-derived collagen matrix on endothelial progenitor cells: an in vitro study.

Porcine-derived collagen matrix (PDCM) has been reported as a promising alternative to autogenous soft tissue grafts in periodontal plastic surgery. The aim of this study was to analyze the influence of a novel PDCM on endothelial progenitor cells (EPC) in vitro. EPC were isolated from human peripheral blood, cultured and transferred on the PDCM (mucoderm®). Tissue culture polystyrene surface (TCPS) served as control. Cell viability of EPC on PDCM was measured by a MTT and PrestoBlue® assay. Migration ability was tested using a Boyden migration assay. A ToxiLight® assay was performed to analyze the influence of PDCM on adenylate kinase (ADK) release and apoptosis rate of EPC. Using the MTT assay, EPC cultured on PDCM demonstrated a significantly increased cell viability compared to the control group at days 3, 6 and 12 (p each <0.001). According to the PrestoBlue® assay, EPC showed a significant increase of cell viability compared to the control group at 48, 72, and 96 h (p each <0.001). In the Boyden migration assay, a significantly increased EPC migration ability could be observed after 3-12 days (p each ≤0.001). No significantly increased apoptosis rate of EPC on PDCM could be observed with exception after 96 h (p each >0.05). Overall, our results suggest a good biocompatibility of PDCM without any cytotoxic effects on EPC, which might support a rapid revascularization and therefore a sufficient ingrowth of the PDCM.

Impact of proangiogenic factors on organization and biodegradation of a collagen matrix. An immunohistochemical study in rats

The aim of the present study was to investigate the impact of proangiogenic factors [erythropoetin (EPO), human growth hormone (HGH), fibroblast growth factor (FGF), and platelet derived growth factor (PDGF-BB)] on the organization and biodegradation of a porcine-derived collagen matrix (CM) in rats. Collagen matrix specimens were soak-loaded either with EPO, HGH, FGF or PDGF-BB, each delivered in three concentrations (high, medium, low), and randomly allocated in unconnected subcutaneous pouches separated surgically on the back of 112 Wistar rats, which were divided into four groups (4, 7, 14 and 60days of healing). Tissue biopsies were prepared for histological (e.g. CM thickness - TH, tissue contact - TC) and immunohistochemical (collagen type III - C3) analysis. Collagen matrix specimens of the control group were associated with an ingrowth of C3 fibres and subsequently an increase in TH at 7 (11%), 14 (20%) and 60 (21%). Factor application in different concentrations was commonly associated with a faster organization, but also significant biodegradation of CM at 7 (PDGF-M, FGF-M, HGH-H) and 14days (EPO-H, HGH-L). All groups investigated revealed a comparable increase in mean TC values over time. Within the limits of the present study, it was concluded that all proangiogenic factors investigated were associated with a pronounced organization of CM by C3 fibres and a biodegradation of the matrix body. EPO may serve as an alternative to PDGF-BB.

Treatment of soft tissue recessions at titanium implants using a resorbable collagen matrix: a pilot study

To histologically assess the effectiveness of a porcine-derived collagen matrix (CM) and a subepithelial connective tissue graft (CTG) for the coverage of single mucosal recessions at osseointegrated dental implants. Chronic-type mucosal Miller Class I-like recessions (mean clinical defect height: 0.67±0.33-1.16±0.19mm) were established at the buccal aspect of titanium implants with platform switch in six beagle dogs. The defects were randomly allocated to either (1) coronally advanced flap surgery (CAF)+CM, (2) CAF+CTG or (3) CAF alone. At 12weeks, histomorphometrical measurements were made (e.g.) between the implant shoulder (IS) and the mucosal margin (PM) and IS and the outer contour of the adjacent soft tissue (mucosal thickness [MT]). All treatment procedures investigated were associated with an almost complete soft tissue coverage of the defect area (i.e. coronal positioning of PM relative to IS). Mean IS-PM and MT values tended to be increased in both CAF+CM (1.04±0.74mm/0.71±0.55mm) and CAF+CTG (0.88±1.23mm/0.62±0.66mm) groups when compared with CAF (0.16±0.28mm/0.34±0.23mm) alone. These differences, however, did not reach statistical significance. Within the limits of this pilot study, it was concluded that all treatment procedures investigated were effective in covering soft tissue recessions at titanium implants.

Interventions for replacing missing teeth: management of soft tissues for dental implants

Dental implants are usually placed by elevating a soft tissue flap, but in some instances, they can also be placed flapless reducing patient discomfort. Several flap designs and suturing techniques have been proposed. Soft tissues are often manipulated and augmented for aesthetic reasons. It is often recommended that implants are surrounded by a sufficient width of attached/keratinised mucosa to improve their long-term prognosis. To evaluate whether (1a) flapless procedures are beneficial for patients, and (1b) which is the ideal flap design; whether (2a) soft tissue correction/augmentation techniques are beneficial for patients, and (2b) which are the best techniques; whether (3a) techniques to increase the peri-implant keratinised mucosa are beneficial for patients, and (3b) which are the best techniques; and (4) which are the best suturing techniques/materials. The following electronic databases were searched: the Cochrane Oral Health Group Trials Register (to 9 June 2011), the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2011, Issue 2), MEDLINE via OVID (1950 to 9 June 2011), EMBASE via OVID (1980 to 9 June 2011). Several dental journals were handsearched. There were no language restrictions. All randomised controlled trials (RCTs) of root-form osseointegrated dental implants, with a follow-up of at least 6 months after function, comparing various techniques to handle soft tissues in relation to dental implants. Outcome measures, according to the different hypotheses, were: prosthetic and implant failures, biological complications, aesthetics evaluated by patients and dentists, postoperative pain, marginal peri-implant bone level changes on periapical radiographs, patient preference, ease of maintenance by patient, soft tissue thickness changes and attached/keratinised mucosa height changes. Screening of eligible studies, assessment of the methodological quality of the trials and data extraction were conducted at least in duplicate and independently by two or more review authors. Trial authors were contacted for missing information. Results were expressed using risk ratios for dichotomous outcomes and mean differences for continuous outcomes with 95% confidence intervals. Seventeen potentially eligible RCTs were identified but only six trials with 138 patients in total could be included. One study was at low risk of bias, two studies were judged to be at unclear risk of bias and three at high risk of bias. Two trials (56 patients) compared flapless placement of dental implants with conventional flap elevation, one trial (10 patients) compared crestal versus vestibular incisions, one trial (20 patients) Erbium:YAG laser versus flap elevation at the second-stage surgery for implant exposure, one split-mouth trial (10 patients) evaluated whether connective tissue graft at implant placement could be effective in augmenting peri-implant tissues, and one trial (40 patients) compared autograft with an animal-derived collagen matrix to increase the height of the keratinised mucosa. On a patient, rather than per implant basis, implants placed with a flapless technique and implant exposures performed with laser induced statistically significantly less postoperative pain than flap elevation. Sites augmented with soft tissues connective grafts showed a better aesthetic and thicker tissues. Both palatal autografts or the use of a porcine-derived collagen matrix are effective in increasing the height of keratinised mucosa at the price of a 0.5 mm recession of peri-implant soft tissues. There were no other statistically significant differences for any of the remaining analyses. There is limited weak evidence suggesting that flapless implant placement is feasible and has been shown to reduce patient postoperative discomfort in adequately selected patients, that augmentation at implant sites with soft tissue grafts is effective in increasing soft tissue thickness improving aesthetics and that one technique to increase the height of keratinised mucosa using autografts or an animal-derived collagen matrix was able to achieve its goal but at the price of a worsened aesthetic outcome (0.5 mm of recession). There is insufficient reliable evidence to provide recommendations on which is the ideal flap design, the best soft tissue augmentation technique, whether techniques to increase the width of keratinised/attached mucosa are beneficial to patients or not, and which are the best incision/suture techniques/materials. Properly designed and conducted RCTs, with at least 6 months of follow-up, are needed to provide reliable answers to these questions.