Collagen Matrix vs. Autogenous Connective Tissue Graft for Soft Tissue Augmentation: A Systematic Review and Meta-Analysis

The Effect of Connective Tissue Graft Compared to Concentrated Growth Factor Graft on Buccal Peri-Implant Gingival Thickness: A 12-month Randomized Controlled Clinical Trial

BACKGROUND

Attached gingival phenotype has a crucial impact on the implant's durability and its future success.

PURPOSE

This study aims to measure and compare buccal peri-implant gingival thickness following grafting with connective tissue graft (CTG) and the concentrated growth factor (CGF) graft.

STUDY DESIGN, SETTING, SAMPLE

This is a split-mouth designed randomized controlled clinical study in which a total of 20 aged 18 to 55 have bilateral missing teeth in the maxillary premolar region with less than 2 mm of healthy peri-implant gingival thickness. Patients were excluded if they were smokers, had poor oral hygiene, had uncontrolled widespread periodontal disease, or had a history of radiation treatment. The same surgical protocol was followed for each study participant, where an independent blinded medical practitioner assigned the first stage side to be treated with CTG, while the second stage side with CGF 2 weeks later.

EXPOSURE VARIABLE

The primary exposure variable of this study was the gingival grafting technique; CTG or CGF.

OUTCOME VARIABLE

The primary outcome variable was the buccal peri-implant gingival thickness. Gingival thickness was measured at six different times; immediately before the procedure (T0), after 30 days (T1), after 45 days (T2), after 3 months (T3), after 6 months (T4), and after 12 months (T5).

COVARIATES

The covariates were age, sex general health, and periodontal status.

ANALYSIS

The statistical analysis; repeated measures analysis of variance test was used to compare the gingival thickness between the studied follow-up times within each group. The level of significance was set at ≤ 0.05.

RESULTS

The sample was composed of 40 treatment sites of 20 patients. The mean age of the sample was 32 years and 45% were male. The mean gingival thickness value of the CTG group was 1.62 mm with a (standard deviation = 0.18) compared to 1.28 mm for the CGF group with (standard deviation = 0.20) and an overall P value (0.001) at T5.

CONCLUSIONS AND RELEVANCE

CTG showed to have better gingival thickness than CGF in managing peri-implant buccal gingival thickness deficiency.

Periodontal phenotype modification in orthodontic patients

OBJECTIVE

The purpose of this study was to assess the feasibility of phenotype modification in orthodontic patients using combined bone and soft tissue grafting substitutes.

CLINICAL CONSIDERATION

The surgical procedure was conducted on 18 patients (3 males, 15 females). Periodontal phenotype modification was conducted using demineralized freeze-dried bone allograft and a xenogeneic collagen matrix. The following parameters were recorded for each tooth at baseline and 12-month follow-up: O'Leary plaque index (PI), probing depth (PD), bleeding on probing (BOP), gingival thickness (GT), keratinized tissue width (KTW), gingival recession (GR), and vestibular depth (VD). The results showed a statistically significant increase in GT (2.02 ± 0.39 mm), KTW (1.11 ± 0.82 mm), and VD (0.18 ± 1.16 mm) (p < 0.05). GR was also significantly decreased (1.02 ± 0.99 mm) (p < 0.05).

CONCLUSION

Within the limitation of this study, the proposed approach enhanced the periodontal condition in orthodontic patients. However, further studies with a larger sample size are needed to ensure long-term stability.

CLINICAL SIGNIFICANCE

Hard and soft tissue conditions have paramount importance for long-term periodontal stability. Phenotype modification in orthodontic patients can diminish the probability of adverse consequences and result in optimal esthetic outcomes. The proposed technique using combined bone and soft tissue substitutes indicated promising results and could be recommended in orthodontic patients with thin periodontal phenotypes.

Collagen-Based Medical Devices for Regenerative Medicine and Tissue Engineering

Assisted reproductive technologies are key to solving the problems of aging and organ defects. Collagen is compatible with living tissues and has many different chemical properties; it has great potential for use in reproductive medicine and the engineering of reproductive tissues. It is a natural substance that has been used a lot in science and medicine. Collagen is a substance that can be obtained from many different animals. It can be made naturally or created using scientific methods. Using pure collagen has some drawbacks regarding its physical and chemical characteristics. Because of this, when collagen is processed in various ways, it can better meet the specific needs as a material for repairing tissues. In simpler terms, collagen can be used to help regenerate bones, cartilage, and skin. It can also be used in cardiovascular repair and other areas. There are different ways to process collagen, such as cross-linking it, making it more structured, adding minerals to it, or using it as a carrier for other substances. All of these methods help advance the field of tissue engineering. This review summarizes and discusses the current progress of collagen-based materials for reproductive medicine.

Comparative analysis of xenogeneic collagen matrix and autogenous subepithelial connective tissue graft to increase soft tissue volume around dental implants: a systematic review and meta-analysis

OBJECTIVE

The gold standard for a soft tissue augmentation around implants is a subepithelial connective tissue graft (CTG), but the xenogeneic collagen matrices (XCM) started to be used as an alternative. This systematic review aimed to assess the effectiveness XCM in comparison to CTG for the increasing the thickness of the soft tissue around implants.

DATA

All studies included at least two parallel groups comparing the use of CTG and XCM with a minimum follow-up of 3 months. As the primary outcome, the amount of soft tissue thickness gain after soft tissue augmentation with XCM or CTG was assessed. Secondary outcomes were clinical and patient-related outcomes; evaluation of aesthetic outcomes, patient-reported outcomes measures (PROMs) and complications. Eligible studies were selected based on the inclusion criteria. Meta-analysis was applied whenever possible. The quality of the evidence of studies including in meta-analysis was assessed using the GRADE approach.

SOURCE

A systematic literature search up to January 2022 was conducted using the following electronic databases: PubMed (MEDLINE), Scopus, Cochrane Library, LILACS, eLIBRARY.RU. Unpublished researches, the gray literature, nonprofit reports, government studies and other materials were reviewed electronically using an EASY search. An additional manual search was carried out in November 2022.

STUDY SELECTION

Of the 1376 articles from the initial search, 8 randomized controlled trials (RCTs) (306 patients and 325 implants) were included in this systematic review, and 7 studies were part of the meta-analysis. Meta-analysis revealed that XCM is less effective than the CTG in increasing soft tissue thickness around dental implants. However, XCM also provides soft tissue thickness gain and can be recommended for use in various clinical situations.

CLINICAL SIGNIFICANCE

Previous systematic reviews and meta-analyses have shown that autologous grafts are more effective than collagen matrices in increasing soft tissue thickness, however, the latter can be used as an alternative. Studies included in previous systematic reviews varied in design, which could lead to limitations. The present systematic review and meta-analysis includes for the first time only randomized controlled clinical trials with collagen matrix of xenogeneic origin in the test group. Tight eligibility criteria were established, and the main parameter studied was soft tissue thickness. It was found that xenogeneic collagen matrix is effective for increasing soft tissue thickness around dental implants, however, the results obtained using an autogenous connective tissue graft are superior.

EMD-liquid contributes to tissue thickness gain in soft tissue augmentation using a collagen matrix

OBJECTIVES

To investigate the function of enamel matrix derivative (EMD)-liquid compared to EMD-gel (original Emdogain® with polyglycolic acid-carrier) in inducing soft tissue regeneration using a rat dorsal model.

MATERIAL AND METHODS

Four subcutaneous pouches were created through dorsal skin incisions in 18 female Wistar rats and randomly allocated to the following groups: (1) sterile saline + non-crosslinked collagen matrix (CM), (2) EMD-gel + CM, and (3) EMD-liquid + CM. After 2 and 4 weeks of healing, the specimens were harvested and stained with Goldner's trichrome, hematoxylin and eosin, and were immunohistochemically stained with an anti-CD31 antibody.

RESULTS

The EMD-liquid group showed the thickest connective tissue compared to the other groups, with statistical significance both at 2 (p < 0.001) and 4 weeks (p = 0.011 and 0.023, respectively). The number of multinucleated giant cells was not significantly different among the groups for both periods. Moreover, there was a tendency to have more blood vessels over a longer period, and the highest number of blood vessels was observed in the EMD-liquid group at 4 weeks (p = 0.009 and 0036, respectively).

CONCLUSION

EMD-liquid-treated CM is advantageous compared to using CM alone or EMD-gel-treated CM, owing to the histomorphometric results that show significantly increased soft tissue thickness and number of blood vessels when EMD-liquid was pre-primed to CM.

CLINICAL RELEVANCE

EMD with a liquid carrier may be an appropriate biologic supplement to provide cell-inducing properties to the CM scaffold and is clinically more beneficial for phenotype modification therapy than CM only and EMD-gel-treated CM.

Biomaterials in Medical Applications

Natural biomaterials are materials extracted from living organisms or their by-products [...].

Influence of using collagen on the soft and hard tissue outcomes of immediate dental implant placement: A systematic review and meta-analysis

OBJECTIVE

To compare the effects of bone grafting materials, collagen-infused grafting materials, and no grafting materials on the soft and hard tissue outcomes when an immediate implant is placed.

MATERIALS AND METHODS

In addition to hand searching, electronic searches were performed in Pubmed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL). Only RCTs were included in our review. The Cochrane ROB 2.0 tool was used to assess the risk of bias (ROB). Two subgroups were used to evaluate implant failure rate, buccal bone resorption, soft tissue thickness, and esthetic scores. In the meta-analysis, both the fixed-effects model and the random-effects model were employed.

RESULT

7 RCTs were selected after screening 580 studies, and 205 patients were included in the review, with 279 implants. Two RCTs were at low bias of risk, three were at moderate bias, and two were deemed at high risk of bias. The failure rate (95% CI: 0.17 to 11.84) and soft tissue thickness were not significantly different between collagen with bone grafting materials and without bone grafting materials. On the basis of the failure rate and buccal bone thickness, there was no significant difference between collagen with bone grafting materials and bone grafting materials. While we found collagen with bone grafting materials could have a significant advantage on the buccal bone thickness (MD: -0.43,95% CI -0.72 to -0.41) and esthetic outcome (MD: -1.23,95% CI -1.90 to -0.55).

CONCLUSION

In the statement of immediate implant implantation, the thickness of the buccal bone and esthetic outcomes did significantly benefit from bone grafting materials with collagen inserted in the "jumping gap".

Comparison of Sub-epithelial Connective Tissue Graft and Platelet Rich Fibrin in Peri-implant Soft Tissue Augmentation: A Randomized Clinical Split-mouth Study

Aims and Background:

Gingival phenotype has a crucial impact on the peri-implant marginal bone stability. The aim of this clinical trial is to assess and compare the efficacy of the sub-epithelial connective tissue graft (SCTG) and platelet-rich fibrin (PRF) in improving the peri-implant soft tissue phenotype and enhancing esthetic outcomes.

Materials and Methods:

The present study was a split-mouth randomized controlled clinical trial. A total of ten patients who had bilateral missing teeth in the maxillary esthetic zone with a thin gingival phenotype were included in this study. For each study participant, one randomly selected site was treated with SCTG, while the other was treated with PRF membrane during dental implant placement. Treatment outcomes included the assessment of the facial gingival thickness using cone-beam computed tomography (CBCT) at the baseline (T0) and 6 months postoperatively (T1), and the Pink esthetic score (PES) at T1 and 3 months later after prosthesis placement (T2).

Results and Discussion:

Both treatment options resulted in a significant increase in gingival tissue thickness at T1 compared with T0, and in PES at T2 compared with T1 (p ˂ 0.05).

Conclusion:

PRF is an effective alternative to SCTG in augmenting peri-implant soft tissue phenotype and improving esthetic outcomes. This would help overcome the complications associated with harvesting the SCTG and increasing patients’ satisfaction.

Clinical Trial Registration ID: ISRCTN11961919.

Management of inadequate width of attached gingiva using mucograft

Attached gingiva around the teeth is crucial in preserving periodontal health. Plaque development and soft-tissue recession are both prevented by adequate attached gingiva. The processes for harvesting soft-tissue grafts are frequently accompanied by some level of morbidity which results in commercially available xenogeneic collagen matrices. The blood clot is more effectively stabilized by this collagen matrix, which also promotes vascularization. Furthermore, this biomaterial enhances root coverage and keratinized gingiva regeneration in both width and thickness. The purpose of the case report is to increase the width of attached gingiva using Mucograft^®. This case report highlights a case scenario where a patient presented with probing depth of 6-8 mm in relation to 24, 25, 26, 27, and 28, Grade I mobility in relation to 25.26, and 1 mm of the width of attached gingiva in relation to 25, 26, and 27. Flap surgery was done and simultaneously vestibular deepening was done in relation to 25, 26, and 27, and mucograft was placed and stabilized. On a 3-month follow-up, probing pocket depth was 3 mm and 4 mm of width of the attached gingiva was seen in 25, 26, and 27. The Mucograft^® was beneficial in this clinical case for the purpose of extending the width of the associated gingiva, making it a feasible treatment option for soft-tissue augmentation.

Preliminary study of silk fibroin porous scaffold for oral soft-tissue thickening

OBJECTIVES

This study aimed to investigate the feasibility of three different concentrations of silk-fibroin porous scaffolds applied to oral soft-tissue thickening in vivo.

METHODS

Silk-fibroin scaffolds with three different concentrations (1 wt%, 3 wt%, and 5 wt%; denoted as SF1, SF3, and SF5, respectively) were prepared by freeze drying and methanol enhancement. The scaffolds were characterized by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and thermogravimetric analysis. Pore size, porosity, and in vitro degradation rate were also evaluated. The three groups of scaffold materials (the experimental sides) and the collagen matrix (the control side) were implanted into the oral mucosa of New Zealand white rabbits. Changed in mucosa thickness before and 3 months after operation were compared. The in vivo metabolism and regeneration effect of each group were observed by histological hematoxylin-eosin (HE) and Masson staining.

RESULTS

SEM showed that the three groups of scaffolds were all cross-linked porous structures. XRD and FTIR showed that the three scaffolds were dominated by a relatively stable Silk Ⅱ structure, which degraded more slowly in vitro. Among them, SF3 had the largest pore size (133.40 μm±22.85 μm) and moderate porosity (90.05%±6.68%). In vivo results showed that the thickening effect of SF1 was similar to that of the control group because of insufficient space-maintenance property. Meanwhile, the properties of SF3 and SF5 were more stable, and the thickening effect was significantly better than those of the control group. However, unlike SF5 that induced obvious inflammation, SF3 showed better degradation, more fibrosis and angiogenesis, and less inflammatory response in vivo.

CONCLUSIONS

Silk-fibroin scaffolds can be applied to effectively thicken soft tissues, among which SF3 (3 wt%) silk fibroin scaffold exhibited the best physicochemical properties, histocompatibility, and mucosal-thickening effect.

Connective tissue graft versus xenogeneic collagen matrix for soft tissue augmentation at implant sites: a randomized-controlled clinical trial

OBJECTIVES

The purpose of this randomized clinical trial (RCT) is to compare xenogeneic collagen matrix (XCM) versus subepithelial connective tissue graft (SCTG) to increase soft tissue thickness at implant site.

MATERIALS AND METHODS

The study was a randomized, parallel-group controlled investigation. Thirty patients underwent buccal soft tissue thickness augmentation at the stage of implant placement by two different methods: SCTG (control group) and XCM (test group). Primary outcome was the amount of buccal soft tissue thickness gain, 3 months after the intervention. Secondary outcomes were the operation time, the amount of keratinized mucosa (KM), pain syndrome (PS), and patients' quality of life (QL). Histologic evaluation was also performed.

RESULTS

The amount of soft tissue thickness gain was 1.55±0.11 mm in SCTG group, and 1.18±0.11mm in XCM group. The difference between the SCTG and XCM was -0.366 (-0.66 to -0.07; p=0.016). Operation time with XCM was 8.4 (3.737 to 13.06) min shorter than that with the SCTG (p=0.001). KT, PS, and QL for both groups were not statistically significantly different at any time point (p>0.05). At histological examination, the general picture in both groups was similar. No significant differences between the studied groups in most indices, except for the average and maximum formation thickness, cellularity of the basal, mitotic activity and also maximum length of rete ridges.

CONCLUSION

Within limitations, this study demonstrates that the use of SCTG provides a statistically significant superior soft tissue thickness gain than XCM for soft tissue augmentation procedures around implants.

CLINICAL RELEVANCE

XCM can be used as the method of choice for increasing the thickness of soft tissues.

Histomorphometric Analysis of Differential Regional Bone Regeneration Induced by Distinct Doped Membranes

Our objective is to evaluate the regional regenerative potential of calvarial bone in critical-sized defects in a rabbit model using novel nanostructured silica-loaded membranes doped with zinc or doxycycline. Nanostructured membranes of (MMA)₁-co-(HEMA)₁/(MA)₃-co-(HEA)₂ loaded with 5 wt% of SiO₂ nanoparticles (HOOC-Si-Membranes) were doped with zinc (Zn-HOOC-Si-Membrane) or doxycycline (Dox-HOOC-Si-Membrane). Critical bone defects were created on six New-Zealand-breed rabbit skulls and covered with the membranes. A sham defect without a membrane was used as the control. After six weeks, a histological analysis (toluidine blue technique) was employed to determine the area percentages of newly formed bone, osteoid bone, and soft tissue. The measurements were performed by dividing the total defect area into top (close to the membrane) and bottom (close to the dura mater) regions, or peripheral (adjacent to the old bone) and central (the sum of the remaining zones) regions. The peripheral regions of the defects showed higher osteogenic capacity than the central areas when the membranes were present. The proportion of new bone adjacent to the dura was similar to that adjacent to the membrane only when the HOOC-Si-Membranes and Zn-HOOC-Si-Membranes were used, indicating a direct osteoinductive effect of the membranes.

Treating Gingival Recessions Using Coronally Advanced Flap or Tunnel Techniques with Autografts or Polymeric Substitutes: A Systematic Review and Meta-Analysis

Gingival recessions are a prevalent oral mucosa alteration. To solve this pathology, palatal mucosa or polymeric soft tissue substitutes are used when performing coronal advanced flap (CAF) or tunnel (TUN) surgical techniques. To evaluate which is the most successful approach, a literature review and meta-analysis were conducted. For the electronic search the National Library of Medicine, the Cochrane Oral Health Group Trials Register, EMBASE and WOS were used. Pooled data for the percentage of root coverage was collected and weighted means were calculated. Heterogeneity was determined using the Higgins (I²) statistic and a random-effects model was applied. Thirteen studies were included in the systematic review (12 randomized and 1 controlled clinical trials) in which both techniques (394 patients) were compared with a follow-up of 4 to 12 months. Galbraith and Baujat plots were used to control for the presence of potential outliers. After performing the meta-analysis (11 studies), the mean root coverage was similar when using the TUN or CAF techniques (p = 0.49). The only differences between the two were found for single recessions, where CAF offered a higher percentage of root coverage (mean difference = 4.98%; p = 0.006). There were no differences when applying an autograft or a polymeric substitute with either of the two tested surgical techniques (p = 0.445).

In Vitro Biodegradation Pattern of Collagen Matrices for Soft Tissue Augmentation

Collagen matrices have become a great alternative to the use of connective tissue grafts for soft tissue augmentation procedures. One of the main problems with these matrices is their volume instability and rapid degradation. This study has been designed with the objective of examining the degradation of three matrices over time. For this purpose, pieces of 10 × 10 mm² of Fibro-Gide, Mucograft and Mucoderm were submitted to three different degradation tests-(1) hydrolytic degradation in phosphate buffer solution (PBS); (2) enzyme resistance, using a 0.25% porcine trypsin solution; and (3) bacterial collagenase resistance (Clostridium histolyticum)-over different immersion periods of up to 50 days. Weight measurements were performed with an analytic microbalance. Thickness was measured with a digital caliper. A stereomicroscope was used to obtain the matrices' images. ANOVA and Student-Newman-Keuls tests were used for mean comparisons (p < 0.05), except when analyzing differences between time-points within the same matrix and solution, where pair-wise comparisons were applied (p < 0.001). Fibro-Gide attained the highest resistance to all degradation challenges. The bacterial collagenase solution was shown to constitute the most aggressive test as all matrices presented 100% degradation before 14 days of storage.