Acellular dermal matrix allografts to achieve increased attached gingiva. Part 2. A histological comparative study

Micro-needling versus acellular dermal matrix in RT1 gingival recession coverage: A randomized clinical trial

AIMS

This randomized trial assessed for the first time the efficacy of coronally advanced flap (CAF) followed by micro-needling (MN) in contrast to CAF with acellular dermal matrix (ADM) on gingival thickness (GT, primary outcome), keratinized tissue width (KTW), clinical attachment level (CAL), probing depth (PD), recession depth (RD), recession width (RW), recession reduction (Rec-Red), complete root coverage (CRC) and percentage of root coverage (all secondary outcomes) in management of RT1 gingival recession in patients with thin gingival phenotype.

METHODS

A total of 24 patients (n = 24) with a thin gingival phenotype and single RT1 gingival recession in the aesthetic zone were randomly allocated to test- (CAF + MN; n = 12) or control group (CAF + ADM; n = 12). All clinical parameters were evaluated at baseline, 3 and 6 months.

RESULTS

Both groups independently demonstrated significant gain in GT, RW, RD, CAL, PD, Rec-Red, CRC and percentage of root coverage, with reduced PI and BOP (p < .05) at 3 and 6 months, without intergroup differences (p > .05). At 6 months, KTW gain was significantly higher in CAF + MN (5.08 ± 0.9 mm) than in CAF + ADM-group (4.25 ± 1.06 mm; p < .05). Stepwise linear regression model with GT as dependent variable showed that base-line GT was the only statistically significant predictor for GT with a direct correlation between base-line GT and GT after 6 months.

CONCLUSION

CAF followed by MN could represent a promising graft-less approach for increasing gingival thickness, comparable to CAF with ADM, with superior keratinized tissue width improvement, in the treatment of RT1 recession defects in patients with thin gingival phenotype.

Soft tissue management around dental implant in esthetic zone - the current concepts and novel techniques

It has been said, 'Bone sets the tone, but tissue is the issue.' In the field of implantology, while significant breakthroughs have been achieved in hard tissue regeneration, clinicians find it more challenging to handle soft tissue complications around dental implants. Successfully managing soft tissue around dental implants requires clinicians to have comprehensive knowledge of proper implant placement, prosthetic design and tissue management, and a high level of surgical skills for soft tissue augmentation and grafting. Autogenous gingival grafts can be utilized in various clinical situations, providing surgeons with great potential and freedom to enhance the quality and quantity of peri-implant soft tissue. Emerging trends, such as digital tools for treatment planning, minimally invasive surgical approaches, and innovative biomaterials, can also contribute to a more pleasing outcome. By elucidating these multifaceted considerations, this review will serve as a valuable resource for clinicians aiming to achieve functional and aesthetic excellence in implant-based oral rehabilitation.

Application of pulsed electric field technology to skin engineering

Tissue engineering encompasses a range of techniques that direct the growth of cells into a living tissue construct for regenerative medicine applications, disease models, drug discovery, and safety testing. These techniques have been implemented to alleviate the clinical burdens of impaired healing of skin, bone, and other tissues. Construct development requires the integration of tissue-specific cells and/or an extracellular matrix-mimicking biomaterial for structural support. Production of such constructs is generally expensive and environmentally costly, thus eco-sustainable approaches should be explored. Pulsed electric field (PEF) technology is a nonthermal physical processing method commonly used in food production and biomedical applications. In this review, the key principles of PEF and the application of PEF technology for skin engineering will be discussed, with an emphasis on how PEF can be applied to skin cells to modify their behaviour, and to biomaterials to assist in their isolation or sterilisation, or to modify their physical properties. The findings indicate that the success of PEF in tissue engineering will be reliant on systematic evaluation of key parameters, such as electric field strength, and their impact on different skin cell and biomaterial types. Linking tangible input parameters to biological responses critical to healing will assist with the development of PEF as a sustainable tool for skin repair and other tissue engineering applications.

Living cellular constructs for keratinized tissue augmentation: A 13-year follow-up from a split-mouth randomized, controlled, clinical trial

BACKGROUND

A 13-year follow-up was conducted of a short-term investigation of the use of living cellular construct (LCC) versus free gingival graft (FGG) for keratinized tissue width (KTW) augmentation in natural dentition, to evaluate the long-term outcomes and assess the changes occurring since the end of the original 6-month study.

METHODS

Twenty-four subjects out of the original 29 enrolled participants were available at the 13-year follow-up. The primary endpoint was the number of sites demonstrating stable clinical outcomes from 6 months to 13 years (defined as KTW gain, stability, or ≤0.5 mm of KTW loss, together with reduction, stability, or increase of probing depth, and recession depth [REC] ≤0.5 mm). Secondary outcomes included the assessment of KTW, attached gingiva width (AGW), REC, clinical attachment level, esthetics, and patient-reported outcomes at the 13-year visit, assessing the changes from baseline to 6 months.

RESULTS

Nine sites per group (42.9%) were found to have maintained stable (≤0.5 mm or improved) clinical outcomes from 6 months to 13 years. No significant differences were observed for the clinical parameters between LCC and FGG from 6 months to 13 years. However, the longitudinal mixed model analysis showed that FGG delivered significantly better clinical outcomes over 13 years (p < 0.01). LCC-treated sites exhibited superior esthetic outcomes compared to FGG-treated sites at 6 months and 13 years (p < 0.01). Patient-evaluated esthetics were significantly higher for LCC over FGG (p < 0.01). Patient overall treatment preference was also in favor of LCC (p < 0.01).

CONCLUSIONS

A similar stability of the treatment outcomes from 6 months to 13 years was found for LCC- and FGG-treated sites, with both approaches shown to be effective in augmenting KTW and AGW. However, superior clinical outcomes were found for FGG over 13 years, while LCC was associated with better esthetics and patient-reported outcomes than FGG.

Long-term evaluation of peri-implant keratinized mucosa stability after free epithelialized graft and keratinized mucosa shifting procedures: A retrospective study up to 13 years

OBJECTIVES

This study aimed to assess the risk of less than 2 mm keratinized mucosa (KM) width occurrence after free epithelialized graft (FEG) and keratinized mucosa shifting (KMS) procedures using survival analysis. In addition, KM dimensional changes were evaluated.

MATERIALS AND METHODS

This study included 76 implants in 36 patients with insufficient KM (<2 mm). The implants underwent either FEG or KMS procedures. The mid-buccal KM width was measured from surgery to the end of a one 13-year follow-up period.

RESULTS

Mean follow-up durations were 9.2 ± 3.9 years for FEG and 6.3 ± 4.2 years for KMS. Two implants in FEG and nine implants in KMS exhibited a KM width of less than 2 mm during follow-up. The hazard ratios for KMS compared to FEG were 6.48 (crude) and 6.54 (adjusted), both statistically significant (p < .05). The incidence rate of KMS (4.06%) was higher than that of FEG (0.63%), with an average incidence time of 3.38 years for KMS and 8.82 years for FEG post-surgery. FEG showed a significant shrinkage within 6 months (33% ± 22%), whereas KMS demonstrated a gradual decrease over 13 years (34% ± 25%). FEG exhibited significantly greater width change than KMS during a 5-year follow-up (p < .05).

CONCLUSIONS

FEG and KMS enhanced PIKM but exhibited different long-term reduction patterns. FEG demonstrated rapid shrinkage, while KMS displayed gradual and continuous reduction. Moreover, KMS presented a higher risk and incidence of KM width less than 2 mm compared to FEG.

Multiple coronally advanced flap with a selective use of connective tissue graft: A 3-year prospective clinical and histological study

BACKGROUND

The purpose of the present study was to prospectively evaluate the 3-year changes in the gingival dimensions following multiple coronally advanced flap (MCAF) with selective use of connective tissue graft (CTG). In addition, the secondary aim was to histologically identify the factors related to phenotype changes.

METHODS

Twenty patients treated with MCAF and site-specific application of a CTG were available for the 3-year follow-up. Outcome measures included complete root coverage (CRC), recession reduction, keratinized tissue width (KTW), marginal tissue thickness changes, and primary flap position. Biopsies were harvested at one of the sites treated with the adjunct of CTG. All sections were stained with hematoxylin and eosin, Masson trichrome, Verhoeff-van Gieson, tenascin, and alcian blue stain for semiquantitative evaluation.

RESULTS

At 3 years, CRC was detected in 86% of sites treated with MCAF alone and 81% of sites treated with MCAF + CTG. The 47% of sites treated with MCAF + CTG presented an apical shift of primary flap from its original position. Linear regression showed a significant association between KTW change and the initial KTW in MCAF-treated sites, while both initial KTW and position of primary flap were statistically significantly associated factors with KTW changes in the MCAF + CTG group. In all the biopsies examined, there is always a marked and clear separation between the connective tissue of the gingival flap and the palatal connective tissue of the graft.

CONCLUSIONS

The selective use of CTG is an effective treatment for multiple gingival recessions. Only a limited increase in KTW can be expected in a bilaminar technique if, during the healing phases, the connective tissue is maintained completely covered.

Three-dimensional cultures of gingival fibroblasts on fibrin-based scaffolds for gingival augmentation: A proof-of-concept study

OBJECTIVE

Gingival tissue regeneration is associated with several challenges. Tissue engineering regenerates the different components of the tissues, providing three major elements: living cells, appropriate scaffolds, and tissue-inducing substances. This study aimed to regenerate the gingival connective tissue in vitro, using human gingival fibroblasts cultured in three-dimensional fibrin gel scaffolds.

DESIGN

Human gingival fibroblasts were seeded in a novel three-dimensional fibrin gel scaffold and maintained in two media types: platelet lysate media (control) and collagen-stimulating media (test). Cellular viability and proliferation were assessed, and the production of collagen and other extracellular matrix components in these constructs was investigated and compared.

RESULTS

Human gingival fibroblasts cultured in three-dimensional cultures were metabolically active and proliferated in both media. Furthermore, histologic sections, scanning electron microscopy, and quantitative polymerase chain reaction confirmed the production of higher levels of collagen and other extracellular matrix fibers in three-dimensional constructs cultured in collagen-stimulating media.

CONCLUSIONS

Culturing human gingival fibroblasts in a novel three-dimensional fibrin gel scaffold containing collagen-stimulating media resulted in a tissue-equivalent construct that mimics human gingival connective tissue. The impact of these results should be considered for further investigations, which may help to develop a compatible scaffold for gingival soft tissue regeneration and treatment of mucogingival deformities.

Periodontal phenotype modification of complexes periodontal-orthodontic case scenarios: A clinical review on the applications of allogenous dermal matrix as an alternative to subepithelial connective tissue graft

OBJECTIVES

The aim of this review is to address the potential applications of allogenous dermal matrix (ADM), as an alternative to subepithelial connective tissue graft (SCTG), in promoting periodontal phenotype modification (PPM) of challenging periodontal-orthodontic clinical scenarios.

OVERVIEW

The rationale behind the need of changing thin to thick gingival tissues is associated to the superior and more stable treatment outcomes promoted by PPM therapy. PPM, via soft tissue grafting, leads to clinical and histological changes of the pre-established original genetic conditions of the gingiva. Although SCTG-based procedures are recognized as the "gold standard" for the treatment of sites requiring root coverage and gingival augmentation, ADM has been recognized as the most suitable alternative to SCTG, particularly in clinical scenarios where the use of autogenous grafts is not possible. Thus, ADM is considered an optimal option for the treatment of patients with a history (or in need) of orthodontic tooth movement, due its two-fold potential indication: (1) the promotion of periodontal soft tissue phenotype modification; and (2) its use, as a barrier membrane, in hard tissues augmentation procedures.

CONCLUSIONS

ADM is a viable option for soft tissue augmentation, as well as for treatment approaches involving buccal bone gain.

CLINICAL SIGNIFICANCE

Periodontal phenotype modification therapy, when applied in challenging periodontal-orthodontic clinical scenarios, promotes root coverage and prevents the onset and development clinical attachment loss.

A New Matrix for Soft Tissue Management

Gingival recession is a mucogingival defect defined as the apical shifting of the gingival margin in relation to the CEJ. The use of connective tissue autografts allows for the obtention of very satisfactory results but is associated with undoubted disadvantages. The aim of the present work is to carry out a systematic review of the literature using a meta-analysis to investigate the clinical efficacy of xenogeneic collagen matrix (XCM) in the treatment of gingival recessions. This revision was carried out strictly following the guidelines published in the Cochrane Handbook. Thus, a meta-analysis was performed to calculate relative risks and standardized mean differences for each of the variables considered. The results of the meta-analysis show that CAF + CTG was statistically better than CAF + XCM in almost all the variables analyzed: complete root coverage (RR 0.46), mean root coverage (SMD −0.89), recession reduction (SMD −0.98), clinical attachment level (SMD −0.63) and gingival thickness (SMD −1.68). Meanwhile, CAF + XCM was slightly better than CAF alone in regard to: mean root coverage (SMD 0.51), recession reduction (SMD 0.47) and gingival thickness (SMD 0.56). It is possible to conclude that CAF + CTG still remains the gold standard in radicular coverage.

Full-Thickness Oral Mucoperiosteal Defects: Challenges and Opportunities

Regenerative engineering strategies for the oral mucoperiosteum, as may be needed following surgeries, such as cleft palate repair and tumor resection, are underdeveloped compared with those for maxillofacial bone. However, critical-size tissue defects left to heal by secondary intention can lead to complications, such as infection, fistula formation, scarring, and midface hypoplasia. This review describes current clinical practice for replacing mucoperiosteal tissue, including autografts and allografts. Potentially paradigm-shifting experimental regenerative engineering strategies for mucoperiosteal wound healing, such as hybrid grafts and engineered matrices, are also discussed. Throughout the review, the advantages and disadvantages of each replacement or regeneration strategy are outlined in the context of clinical outcomes, quality of life for the patient, availability of materials, and cost of care. Finally, future directions for research and development in the area of mucoperiosteum repair are proposed, with an emphasis on identifying globally available and affordable solutions for promoting mucoperiosteal regeneration. Impact statement Unassisted oral mucoperiosteal wound healing can lead to severe complications such as infection, fistulae, scarring, and developmental abnormalities. Thus, strategies for promoting wound healing must be considered when mucoperiosteal defects are incident to oral surgery, as in palatoplasty or tumor resection. Emerging mucoperiosteal tissue engineering strategies, described in this study, have the potential to overcome the limitations of current standard-of-care donor tissue grafts. For example, the use of engineered mucoperiosteal biomaterials could circumvent concerns about tissue availability and immunogenicity. Moreover, employment of tissue engineering strategies may improve the equity of oral wound care by increasing global affordability and accessibility of materials.

Utilizing 3D bioprinted platelet-rich fibrin-based materials to promote the regeneration of oral soft tissue

Oral soft tissue defects remain difficult to treat owing to the limited efficacy of available treatment materials. Although the injectable platelet-rich fibrin (i-PRF) is a safe, autologous source of high levels of growth factors that is often employed to promote the regeneration of oral soft tissue, its effectiveness is restrained by difficulties in intraoperative shaping together with the burst-like release of growth factors. We herein sought to develop a bioactive bioink composed of i-PRF, alginate and gelatin capable of promoting the regeneration of the oral soft tissue. This bioink was successfully applied in 3D bioprinting and exhibited its ability to be shaped to individual patient needs. Importantly, we were also able to significantly prolong the duration of multiple growth factors release as compared to that observed for i-PRF. The growth factor bioavailability was further confirmed by the enhanced proliferation and viability of printed gingival fibroblasts. When deployed in vivo in nude mice, this bioink was further confirmed to be biocompatible and to drive enhanced angiogenic activity. Together, these data thus confirm the successful production of an i-PRF-containing bioink, which is suitable for the individualized promotion of the regeneration of oral soft tissue.

Is there any biomaterial substitute for peri-implant soft tissue phenotype modification? A network meta-analysis of the appraisal literature

Evidence shows that an increased width and thickness of the keratinized mucosa favours peri-implant health. The aim of this network meta-analysis was to compare the clinical effects of alternative biomaterials for peri-implant soft tissue phenotype modification (PSPM) in patients with dental implants when compared to autologous tissue grafts. An electronic search without language or date limitations was performed in four databases and the grey literature for articles published until November 2020. The eligibility criteria included randomized clinical trials (RCTs) evaluating the clinical outcomes of biomaterials for PSPM. A pairwise and network meta-analysis was conducted for each parameter to assess and compare the outcomes between the different treatment arms for the primary and secondary outcomes. A total of 11 RCTs were included in this review. The free gingival graft (FGG) showed the best clinical effect for increasing keratinized mucosa width (KMW). When compared in a network, the FGG demonstrated the best treatment ranking of probability results, followed by connective tissue graft (CTG), acellular dermal matrix (ADM), and xenogeneic collagen matrix (XCM). For the parameters 'mucosa thickness' and 'participant satisfaction with aesthetics', the results were CTG > ADM > XCM and XCM > ADM > CTG, respectively. Autogenous tissue grafts (FGG/CTG) demonstrate the best results in increasing KMW and mucosa thickness when compared to the other biomaterials.

Effectiveness of acellular dermal matrix graft with a coronally advanced flap for the treatment of Miller Class I/II single gingival recession with thin gingival phenotype: study protocol for a split-mouth randomised controlled trial

INTRODUCTION

Gingival recession is one of the most common mucogingival deformities requiring surgical correction. The American Academy of Periodontology Regeneration Workshop recommended connective tissue graft (CTG) combined with coronally advanced flap (CAF) for the treatment of Miller Class I and II single-tooth gingival recession. The disadvantages of harvesting autogenous tissue include postoperative bleeding, pain and discomfort at the donor site, restricted tissue supply, increased morbidity and prolonged operative times. Acellular dermal matrix (ADM) contains undamaged collagen and elastin matrices that can be used as a substitute for CTG during root coverage procedures. However, the use of ADM is still controversial. The objective of this split-mouth; randomised, controlled, clinical study is to evaluate the long-term effects of ADM graft (ADMG) combined with CAF on root coverage, aesthetics and patient satisfaction for the treatment of single gingival recession with thin gingival phenotype.

METHODS AND ANALYSIS

Forty participants with bilateral Miller Class I/II gingival recession will be randomised to receive an ADMG on one side and CTG on the contralateral side, combined with CAF. Gingival recession depth, gingival recession width and keratinised tissue width will be measured at baseline, 2 weeks and 1, 3, 6, 12 and 24 months. Mean root coverage, complete root coverage, root coverage aesthetic score, colour change (∆E) and patient satisfaction will be assessed during follow-up visits.

ETHICS AND DISSEMINATION

The present study has received approval from the Ethics Committee of Peking University School and Hospital of Stomatology (PKUSSIRB-202054029). Data of this study will be registered with the International Clinical Trials Registry Platform. Additionally, we will disseminate the results through scientific journal.

TRIAL REGISTRATION NUMBER

ChiCTR2000033230.

Biocompatibility Evaluation of Human and Porcine Acellular Dermal Matrix on Human Primary Gingival Fibroblasts: In Vitro Comparative Study

Objective  Allogeneic and xenogeneic acellular dermal matrix (ADM) grafts have been used to treat periodontal soft tissue defects. The purpose of the current study was to compare the effect of human ADM (AlloDerm) and porcine ADM (Derma) on human primary gingival fibroblasts in vitro regarding the biocompatibility test.

Materials and Methods  Gingival fibroblasts were obtained from healthy adult gingiva and seeded on AlloDerm or Derma ADM in 96-well plate. The control cells were grown on a surface-treated polystyrene cell-culture plate without matrix. The cells were cultured for 3, 7, and 14 days. The fibroblasts morphology was examined using inverted microscopy, and the cell viability of fibroblasts adherent to the dermal matrix was evaluated using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) cell viability assay after 3, 7, and 14 days in culture. The data were statistically evaluated by one-way analysis of variance. p -Value of 0.05 was considered significant.

Results  Gingival fibroblasts adjacent to the AlloDerm and Derma matrices were healthy, attached to the well, and did not exhibit any cytopathic changes similar to control. There were no statistically significant differences in the cell viability between the gingival fibroblasts attached to Derma and AlloDerm on day 3 ( p = 0.841), day 7 ( p = 0.198), and day 14 ( p = 0.788).

Conclusion  Considering this in vitro study’s limitations, both human and porcine ADM were compatible with the surrounding human primary gingival fibroblasts. No significant differences were observed in the cell viability between the gingival fibroblasts that were attached to Derma and AlloDerm.

Double-layer technique using an ADM and CAF to treat a mandibular incisor with a Cairo RT2 defect: 8.5 year results

INTRODUCTION

The purpose of this case report is to document the 8.5 years result of treatment of a mandibular incisor having a buccal Cairo Recession Type 2 (RT2) gingival recession defect (GRD) using a double-layer technique using an acellular dermal matrix (ADM) with a coronally advanced flap (CAF). To the author's knowledge, no long-term results of this treatment modality in the mandibular incisor area have been reported.

CASE PRESENTATION

A 65-year-old non-smoking female presented with an RT2 GRD on the buccal aspect of tooth #25 (International Standards Organization, ISO #41). Her overall periodontal status was healthy. This GRD was treated using a double-layer of an ADM with a CAF. Tension-free flap advancement was permitted by eliminating a frenum pull. Improved root coverage and stable gingival margins were found after 8.5 years.

CONCLUSION

This report provides evidence to support the use of a double-layer technique using an ADM with a CAF to treat a mandibular incisor with an RT2 GRD.

A Novel Volume-Stable Collagen Matrix Induces Changes in the Behavior of Primary Human Oral Fibroblasts, Periodontal Ligament, and Endothelial Cells

The aim of the present study was to investigate the influence of a novel volume-stable collagen matrix (vCM) on early wound healing events including cellular migration and adhesion, protein adsorption and release, and the dynamics of the hemostatic system. For this purpose, we utilized transwell migration and crystal violet adhesion assays, ELISAs for quantification of adsorbed and released from the matrix growth factors, and qRT-PCR for quantification of gene expression in cells grown on the matrix. Our results demonstrated that primary human oral fibroblasts, periodontal ligament, and endothelial cells exhibited increased migration toward vCM compared to control cells that migrated in the absence of the matrix. Cellular adhesive properties on vCM were significantly increased compared to controls. Growth factors TGF-β1, PDGF-BB, FGF-2, and GDF-5 were adsorbed on vCM with great efficiency and continuously delivered in the medium after an initial burst release within hours. We observed statistically significant upregulation of genes encoding the antifibrinolytic thrombomodulin, plasminogen activator inhibitor type 1, thrombospondin 1, and thromboplastin, as well as strong downregulation of genes encoding the profibrinolytic tissue plasminogen activator, urokinase-type plasminogen activator, its receptor, and the matrix metalloproteinase 14 in cells grown on vCM. As a general trend, the stimulatory effect of the vCM on the expression of antifibrinolytic genes was synergistically enhanced by TGF-β1, PDGF-BB, or FGF-2, whereas the strong inhibitory effect of the vCM on the expression of profibrinolytic genes was reversed by PDGF-BB, FGF-2, or GDF-5. Taken together, our data strongly support the effect of the novel vCM on fibrin clot stabilization and coagulation/fibrinolysis equilibrium, thus facilitating progression to the next stages of the soft tissue healing process.

Histomorphometric Comparison between Two Types of Acellular Dermal Matrix Grafts: A Mini Pig Animal Model Study

Acellular dermal matrix grafts (ADMG) have been used as soft tissue graft substitutes for autografts in periodontal plastic surgical procedures. They have benefits like avoiding a second surgical site and patient morbidity that have been associated with autografts, but there is limited evidence available on their tissue response and wound healing process. This histomorphometric animal model study was carried out in mini pigs and it aimed to compare the two types of ADMG materials of porcine derivative with a control group through observation of parameters like epithelial and Keratinized layer thickness, angiogenesis, cellularity, matrix resorption, and inflammatory infiltrate. The surgical technique involved punctures on the edentulous areas stripping the epithelial tissue and exposing the underlying connective tissue, placement of the ADMGs in the appropriate control and test sites. Following this, gingival biopsies were procured at three different time intervals of 15, 45, and 90 days. There were significant differences in epithelial and Keratinized layer thickness among the three groups. This study concluded that there was no clear consensus on which graft material was superior but it gave an insight into the tissue response and wound healing process associated with the graft materials.

Guided bone regeneration

Guided bone regeneration (GBR) is a surgical procedure that utilizes bone grafts with barrier membranes to reconstruct small defects around dental implants. This procedure is commonly deployed on dehiscence or fenestration defects ≥2 mm, and mixing with autogenous bone is recommended on larger defects. Tension-free primary closure is a critical factor to prevent wound dehiscence, which is critical cause of GBR failure. A barrier membrane should be rigidly fixed without mobility. If the barrier is exposed, closed monitoring should be utilized to prevent secondary infection.

3D Printing Approach in Dentistry: The Future for Personalized Oral Soft Tissue Regeneration

Three-dimensional (3D) printing technology allows the production of an individualized 3D object based on a material of choice, a specific computer-aided design and precise manufacturing. Developments in digital technology, smart biomaterials and advanced cell culturing, combined with 3D printing, provide promising grounds for patient-tailored treatments. In dentistry, the "digital workflow" comprising intraoral scanning for data acquisition, object design and 3D printing, is already in use for manufacturing of surgical guides, dental models and reconstructions. 3D printing, however, remains un-investigated for oral mucosa/gingiva. This scoping literature review provides an overview of the 3D printing technology and its applications in regenerative medicine to then describe 3D printing in dentistry for the production of surgical guides, educational models and the biological reconstructions of periodontal tissues from laboratory to a clinical case. The biomaterials suitable for oral soft tissues printing are outlined. The current treatments and their limitations for oral soft tissue regeneration are presented, including "off the shelf" products and the blood concentrate (PRF). Finally, tissue engineered gingival equivalents are described as the basis for future 3D-printed oral soft tissue constructs. The existing knowledge exploring different approaches could be applied to produce patient-tailored 3D-printed oral soft tissue graft with an appropriate inner architecture and outer shape, leading to a functional as well as aesthetically satisfying outcome.

Root coverage using coronally advanced flap with porcine-derived acellular dermal matrix or subepithelial connective tissue graft: a randomized controlled clinical trial

OBJECTIVE

The aim of this study is to investigate the use of a porcine-derived acellular dermal matrix (MD) in root coverage procedures combined with extended coronally positioned flap (eCAF), in comparison to the subepithelial connective tissue graft (SCTG) associated with the eCAF.

MATERIAL AND METHODS

Eighteen adult patients presenting bilateral type 1 gingival recession were randomly assigned to SCTG or MD groups. Clinical and patient-based outcomes were recorded at 3 and 6 months after the surgical procedure.

RESULTS

Both groups showed a significant reduction in the mean recession height of 3.33 ± 0.89 mm to 1.24 ± 1.10 mm (MD) and 3.21 ± 0.8 mm to 0.83 ± 0.86 mm (SCTG) without difference between groups. Six patients in the test group and eight in the control group obtained complete root coverage. The keratinized tissue height and thickness (KTT) showed a significant increase after 3 and 6 months in both groups. The average KTT gains were 0.39 ± 0.4 mm (MD) and 0.51 ± 0.5 mm (SCTG) (p < 0.05). Performing multivariate analysis suggests that MD addition to coronally advanced flaps may be similar to SCTG.

CONCLUSION

The MD had similar results in comparison to SCTG and in the context of reducing patient morbidity it can be used as an alternative for the treatment of gingival recessions.

CLINICAL RELEVANCE

The SCTG is the gold standard therapy for root coverage. The MD has been widely used in mucogingival surgery as a substitute for SCTG and proposed similar results. A substitute is very important for clinicians and patients. It will give a better postoperative and possibilities to treat multiples recession. (Clinicaltrials.gov Identifier: NCT03675334).

Use of Mucograft Collagen Matrix® versus Free Gingival Graft to Augment Keratinized Tissue around Teeth: A Randomized Controlled Clinical Trial

Objectives

This study aimed to evaluate the mucograft collagen matrix (CM) to increase keratinized tissue around teeth compared to free gingival graft (FGG).

Materials and Methods

The present double-blind, randomized, controlled clinical trial studied 12 patients who had 2 mm or less keratinized gingiva bilaterally around mandibular premolars. The 6-month width of keratinized tissue, periodontal parameters (preoperatively and 1, 3, and 6 months postoperatively), color match, pain, and total surgical time were measured.

Results

The mean dimensional change of keratinized gingiva 6 months postoperatively was 4.1±0.7 mm for FGG and 8±1.7 mm for CM. Periodontal parameters were not affected in the two groups. The CM group had a significantly lower pain, experienced less surgery time, and gained better aesthetics compared to the FGG group.

Conclusion

CM appears to be a suitable substitute for FGG in procedures designed to increase keratinized tissue around teeth. It has remarkable benefits, such as acceptable keratinized tissue gain, less pain, less surgical chair time, and better aesthetics.

Horizontal continuous and apical stretching sutures does not reduce FGG shrinkage: a split-mouth randomized controlled clinical trial

Purpose:

This study aimed to evaluate whether horizontal continuous and apical stretching sutures could reduce FGG shrinkage.

Materials and methods:

In this randomized controlled clinical trial ten patients (20 sites, seven females and three males) ranging from 18 to 53 years (average 39 years) with insufficient keratinized and attached gingiva received FGG in two quadrants of mandible (splitmouth design). Horizontal continuous and apical stretching sutures were used in test sites in addition to common suturing techniques. Clinical parameters including probing depth (PD), the width of keratinized and attached gingiva (KG, AG), the horizontal and vertical dimension of the graft (HD, VD), and graft area (GA) were recorded at baseline and 1, 3, and six months after the operation.

Results:

PD did not differ significantly for six months. The average change of other parameters in test and control sites respectively was as follows: KG increased 5.5 mm and 5.1 mm, AG increased 5.3 mm and 5.1 mm, HD shrinkage was 21.6% and 15.8%, VD shrinkage was 33.7% and 33.2%, GA shrinkage was 47.3% and 43.3%. There were no significant differences between test and control sites in clinical parameters six months after surgery.

Conclusion:

Application of horizontal continuous and apical stretching sutures does not reduce FGG shrinkage.

Extracellular matrix-based scaffolding technologies for periodontal and peri-implant soft tissue regeneration

The present article focuses on the properties and indications of scaffold-based extracellular matrix (ECM) technologies as alternatives to autogenous soft tissue grafts for periodontal and peri-implant plastic surgical reconstruction. The different processing methods for the creation of cell-free constructs resulting in preservation of the extracellular matrices influence the characteristics and behavior of scaffolding biomaterials. The aim of this review is to discuss the properties, clinical application, and limitations of ECM-based scaffold technologies in periodontal and peri-implant soft tissue augmentation when used as alternatives to autogenous soft tissue grafts.

[Research progress on substitutes for autogenous soft tissue grafts in mucogingival surgery]

Mucogingival surgery is a general term for periodontal surgeries that correct aberrant periodontal soft tissues. Conventional mucogingival surgeries with pedicle flap or autologous soft tissue graft for treatment of gingival recession and insufficient keratinized tissues are always related to disadvantages such as need for a second surgery site, limited supplies, and complaints for postoperative discomfort. In this regard, research and application of soft tissue substitutes have gained increasing attention. Various kinds of soft tissue substitutes, including acellular dermal matrix and xenogeneic collagen matrix, have been developed and applied to clinical treatment. This review aims to summarize advances in research of the characteristics and clinical effectiveness of several soft tissue substitutes and provide references for clinical application.

Revascularization of AlloDerm Used during Endoscopic Skull Base Surgery

Objectives  AlloDerm is an acellular dermal matrix often used for reconstruction throughout the body. AlloDerm has been shown to undergo revascularization when used to reconstruct soft tissue such as in abdominal wall reconstruction. In this study, the authors review the literature on revascularization of AlloDerm and demonstrate the histologic findings of AlloDerm after implantation during skull base reconstruction. Study Design  Literature review and case reports. Setting  Tertiary Care Institution Participants  Patients from a tertiary care institution Main Outcome Measures  Histologic slides are evaluated and compared with nonimplanted AlloDerm. Methods  The authors review a case of explanted AlloDerm that had been used for skull base reconstruction after endoscopic skull base surgery. Results  Upon reviewing the histologic slides of explanted AlloDerm to nonimplanted AlloDerm, we demonstrate revascularization of AlloDerm when used in skull base reconstruction. Representative slides will be included. Conclusions  AlloDerm undergoes revascularization when used for skull base reconstruction.

Acellular dermal matrix allograft versus free gingival graft: a histological evaluation and split-mouth randomized clinical trial

OBJECTIVES

This split-mouth controlled randomized clinical trial evaluated clinical and histological results of acellular dermal matrix allograft (ADM) compared to autogenous free gingival graft (FGG) for keratinized tissue augmentation.

MATERIAL AND METHODS

Twenty-five patients with the absence or deficiency of keratinized tissue (50 sites) were treated with FGG (control group) and ADM (test group). Clinical parameters included keratinized tissue width (KTW) (primary outcome), soft tissue thickness (TT), recession depth (RD), probing depth (PD), and clinical attachment level (CAL). Esthetic perception was evaluated by patients and by a calibrated periodontist using visual analog scale (VAS). Histological analysis included biopsies of five different patients from both test and control sites for each evaluation period (n = 25). The analysis included percentage of connective tissue components, epithelial luminal to basal surface ratio, tissue maturation, and presence of elastic fibers. Data were evaluated by ANOVA complemented by Tukey's tests (p < 0.05).

RESULTS

After 6 months, PD and CAL demonstrated no differences between groups. ADM presented higher RD compared to FGG in all periods. Mean tissue shrinkage for control and test groups was 12.41 versus 55.7%. TT was inferior for ADM group compared to FGG. Esthetics perception by professional evaluation showed superior results for ADM. Histomorphometric analysis demonstrated higher percentage of cellularity, blood vessels, and epithelial luminal to basal surface ratio for FGG group. ADM group presented higher percentage of collagen fibers and inflammatory infiltrate.

CONCLUSIONS

Both treatments resulted in improvement of clinical parameters, except for RD. ADM group presented more tissue shrinkage and delayed healing, confirmed histologically, but superior professional esthetic perception.

CLINICAL RELEVANCE

This study added important clinical and histological data to contribute in the decision-making process between indication of FGG or ADM.

[The applications of periodontal gingival surgery. Ⅱ: alternative materials]

The main purposes of periodontal graft surgery include achieving root coverage, improving the clinical attachment level and keratinized tissue, and advancing the procedure of periodontal plastic surgery. Autogenous graft, such as subepithelial connective tissue graft-based procedure, provide the best outcomes for mean and complete root coverage, as well as increase in keratinized tissue. However, a disadvantage of the procedure is in the location of the operation itself: the additional surgical site (palate). Therefore, clinicians are always looking for graft substitutes. This article will discuss the evidence supporting the use of 1) acellular dermal matrix (ADM); 2) xenogeneic collagen matrix (XCM); 3) recombinant human platelet-derived growth factor (rhPDGF); 4) enamel matrix derivative (EMD); 5) guided tissue regeneration (GTR); 6) living cellular construct (LCC), all of which are used in conjunction with coronally advanced flaps as alternatives to autogenous donor tissue. The decision tree for treatments of Miller recession-type defects are also discussed.

Application of an acellular dermal matrix to a rabbit model of oral mucosal defects

Acellular dermal matrices (ADMs) are increasingly used for the restoration of soft-tissue defects of the oral cavity due to their ability to facilitate faster healing and reduce scar formation without rejection. However, few studies have focused on the histopathology and biological mechanisms involved in their use. The aim of the present study was to observe tissue growth, histopathologic changes and altered biomolecular signatures that occur during the repair of oral defects in rabbit models over time, either with or without the employment of ADM. Animals were sacrificed 1, 2 and 4 weeks following surgery and histological changes were evaluated using hematoxylin and eosin staining. Reverse transcription-polymerase chain reaction and western blot analysis were used to determine changes in the expression of vascular endothelial growth factor (VEGF) and glucose transporter 1 (GLUT1). It was demonstrated that wounds treated with ADM exhibited a weak inflammatory reaction and faster epithelialization and revascularization compared with untreated wounds. This may have been caused by the elevated levels of VEGF and GLUT1 protein detected in the ADM-treated defects. Thus, treating wounds of the oral mucosa with an ADM improves pathological responses compared with those with an untreated wound. The current study demonstrates the underlying mechanisms by which ADM promotes wound healing in defects of the oral mucosa and the results provide further evidence for the use of ADM in clinical settings for the repair of mucosal defects.

Acellular dermal matrix and subepithelial connective tissue grafts for root coverage: A systematic review

BACKGROUND

The aim of this systematic review was to evaluate whether patients with gingival recession would benefit from an acellular dermal matrix graft (ADMG) in ways that are comparable to the gold standard of the subepithelial connective tissue graft (SCTG).

MATERIALS AND METHODS

A systematic review and meta-analysis comparing ADMG to SCTG for the treatment of Miller Class I and II recession defects was conducted according to PRISMA guidelines. PubMed, Excerpta Medica Database, and Cochrane Central Register of Controlled Trials databases were searched up to March 2016 for controlled trials with minimum 6 months duration. The primary outcome was root coverage; secondary outcomes included attachment level change, keratinized tissue (KT) change, and patient-based outcomes. Both authors independently assessed the quality of each included trial and extracted the relevant data.

RESULTS

From 158 potential titles, 17 controlled trials were included in the meta-analysis. There were no differences between ADMG and SCTG for mean root coverage, percent root coverage, and clinical attachment level gain. ADMG was statistically better than SCTG for gain in width of KT (-0.43 mm; 95% confidence interval: -0.72, -0.15). Only one study compared patient-based outcomes.

CONCLUSION

This review found that an ADMG would be a suitable root coverage substitute for an SCTG when avoidance of the second surgical site is preferred.

Histologic Evaluation of Acellular Dermal Matrix Allografts in Humans

INTRODUCTION

Acellular dermal matrix (ADM) is a cell-free dermal matrix comprised of a structurally integrated basement membrane complex and extracellular matrix in which collagen bundles and elastic fibers are the main components. There are several commercially available ADM allografts that have different processing methods. This case series reports the histologic presentation of two of the most widely used ADM allografts, referred to as ADM-A and ADM-B, in patients that had specific situations involving reentry.

CASE SERIES

Two patients referred to the Louisiana State University Department of Periodontics, New Orleans, Louisiana, with 1- to 3-mm recession of at least two non-contiguous sites needing soft tissue augmentation, were treated with appropriate mucogingival procedures using ADM-A or ADM-B. After ≈6 to 8 months of healing, and due to clinical findings that necessitated further periodontal procedures, small tissue biopsies were obtained and examined microscopically.

CONCLUSIONS

All samples of ADM (A and B) analyzed after staining with hematoxylin and eosin had a generally similar appearance under light microscopic examination, which suggests they are both well incorporated into native tissues after 6 to 8 months of healing. When stained with Verhoeff-Van Gieson, all samples showed elastin fibers, a finding consistent with previously published light microscopic observations of ADM. There appeared to be a more densely packed elastin pattern in the deep base of ADM-A compared with ADM-B. This might be an indication these two materials have a different healing pathway when used to augment the oral mucosa.

Soft tissue substitutes in non-root coverage procedures: a systematic review and meta-analysis

OBJECTIVES

The present systematic review compared the effectiveness of soft tissue substitutes (STSs) and autogenous free gingival grafts (FGGs) in non-root-coverage procedures to increase keratinized tissue (KT) width around teeth.

MATERIALS AND METHODS

Included studies fulfilled the following main eligibility criteria: (a) preclinical in vivo or human controlled trials using FGG as control, (b) non-root-coverage procedures, and (c) assessment of KT width. Meta-analysis was performed on the gain in KT width (primary outcome variable) and several secondary variables.

RESULTS

Eight human trials with short observation time evaluating five different STSs were identified. FGG yielded consistently significantly (p < 0.001) larger increase in KT width irrespective whether the comparison regarded an acellular matrix or a tissue-engineered STS. Further, FGG yielded consistently ≥2 mm KT width postoperatively, while use of STS did not, in the few studies reporting on this outcome. On the other hand, STSs resulted in significantly better aesthetic outcomes and received greater patient preference (p < 0.001).

CONCLUSIONS

Based on relatively limited evidence, in non-root-coverage procedures, FGG (1) resulted consistently in significantly larger increase in KT width compared to STS and (2) yielded consistently ≥2 mm KT width postoperatively, while STSs did not. STSs yielded significantly better aesthetic outcomes, received greater patient preference, and appeared safe.

CLINICAL RELEVANCE

Larger and more predictable increase in KT width is achieved with FGG, but STSs may be considered when aesthetics is important. Clinical studies reporting relevant posttreatment outcomes, e.g., postop KT width ≥2 mm, on the long-term (>6 months) are warranted.

Use of a Collagen Matrix as a Substitute for Free Mucosal Grafts in Pre-Prosthetic Surgery: 1 Year Results From a Clinical Prospective Study on 15 Patients

Background:

The presence of keratinized tissue around dental implants is more than desirable either from a functional and aesthetic point of view, making soft tissue grafting a common practice in implant rehabilitation. Autogenous soft tissue grafting procedures are usually associated with high morbidity. Aim of this study was to assess the efficacy of a xenogeneic collagen matrix as a substitute for soft tissue grafting around dental implants.

Methods:

15 consecutive patients underwent a vestibuloplasty and grafting, both in the mandible and the maxilla, with a collagen matrix.

Results:

The primary endpoint was to evaluate the resorption of the graft along with the re-epithelization grafted area. The percentage of the resorption was 44,4%, with a mean gain in vestibular height of 3 mm. Secondary endpoints evaluated the clinical appearance, the hemostatic effect and the post-operative pain. All subjects referred minimal pain with no bleeding. No adverse reaction nor infection were noted.

Conclusion:

This study showed that the used collagen matrix can find major interest in those patients who need a greater aesthetic outcome as the matrix has a perfect integration with the surrounding tissues. Furthermore it is strongly recommended for those patients who can bear little pain.

Clinical Significance:

Post-operative morbidity of autologous grafts is the biggest concern of this type of surgery. The possibility to use a soft tissue substitute is a great achievement as morbidity decreases and bigger areas can be treated in a single surgery.

The present study showed the efficacy of a collagen matrix as this kind of substitute.

Preclinical evaluation of collagen type I scaffolds, including gelatin-collagen microparticles and loaded with a hydroglycolic Calendula officinalis extract in a lagomorph model of full-thickness skin wound

Previously, we have developed collagen type I scaffolds including microparticles of gelatin-collagen type I (SGC) that are able to control the release of a hydroglycolic extract of the Calendula officinalis flower. The main goal of the present work was to carry out the preclinical evaluation of SGC alone or loaded with the C. officinalis extract (SGC-E) in a lagomorph model of full-thickness skin wound. A total of 39 rabbits were distributed in three groups, of 13 animals each. The first group was used to compare wound healing by secondary intention (control) with wound healing observed when wounds were grafted with SGC alone. Comparison of control wounds with wounds grafted with SGC-E was performed in the second group, and comparison of wounds grafted with SGC with wounds grafted with SGC-E was performed in the third group. Clinical follow-ups were carried in all animals after surgery, and histological and histomorphometric analyses were performed on tissues taken from the healed area and healthy surrounding tissue. Histological and histomorphometric results indicate that grafting of SGC alone favors wound healing and brings a better clinical outcome than grafting SGC-E. In vitro collagenase digestion data suggested that the association of the C. officinalis extract to SGC increased the SGC-E cross-linking, making it difficult to degrade and affecting its biocompatibility.

Vascularization after treatment of gingival recession defects with platelet-rich fibrin or connective tissue graft

OBJECTIVE

The aim of this study was to evaluate histologically the following treatment of bilateral localized gingival recessions with coronally advanced flap (CAF) combined with platelet-rich fibrin (PRF) or subepithelial connective tissue graft (SCTG).

MATERIALS AND METHODS

Tissue samples were harvested from 14 subjects either 1 or 6 months after the surgeries. The 2-mm punch biopsies were obtained from the mid-portion of the grafted sites. Neutral buffered formalin fixed, paraffin-embedded 5-μm thick tissue sections were stained with hematoxylin eosin and Masson's trichrome in order to analyze the collagen framework, epithelium thickness and rete-peg length. Multiple sequential sections were cut from paraffin-embedded blocks of tissue and immunohistochemically prepared for detection of vascular endothelial growth factor, CD31 and CD34, for the assessment of vascularization.

RESULTS

Rete peg formation was significantly increased in the sites treated with PRF compared to the SCTG group after 6 months (p < 0.05). On the contrary, the number of vessels was increased in the SCTG group compared to the PRF group after 6 months (p < 0.05). No statistically significant differences were observed in the collagen density. Staining intensity of CD31 increased in submucosal area of PRF group than SCTG group after 1 month. Higher staining intensity of CD34 was observed in the submucosal area of PRF group compared with SCTG group after 6 months.

CONCLUSIONS

The results of the present study suggest that in histological evaluation because of its biological compounds, PRF results earlier vessel formation and tissue maturation compared to connective tissue graft.

CLINICAL RELEVANCE

PRF regulated the vascular response associated with an earlier wound healing.

An acellular dermal matrix allograft (Alloderm(®)) for increasing keratinized attached gingiva: A case series

CONTEXT

Adequate amount of keratinized gingiva is necessary to keep gingiva healthy and free of inflammation. Autografts have been used for years with great success to increase the width of attached gingiva. Autografts, however, have the disadvantage of increasing postoperative morbidity and improper color match with the adjacent tissues. Alloderm(®) allograft has been introduced as an alternative to autografts to overcome these disadvantages.

AIM

In this study, the efficacy of alloderm(®) in increasing the width of attached gingiva and the stability of gained attached gingiva was evaluated clinically.

MATERIALS AND METHODS

Five patients with sites showing inadequate width of attached gingiva (≤1 mm) were enrolled for the study. The width of keratinized gingiva and other clinical parameters were recorded at baseline and 9th month postoperatively.

RESULT

In all cases, there is the average increase of about 2.5 mm of attached gingiva and was maintained for 9-month. Percentage shrinkage of the graft is about 75% at the end of 3(rd) month in all cases. Excellent colors match with adjacent tissue has been obtained.

CONCLUSION

The study signifies that Alloderm(®) results in an adequate increase in the amount of attached gingiva and therefore can be used successfully in place of autografts.

Periodontal Soft Tissue Non-Root Coverage Procedures: Practical Applications From the AAP Regeneration Workshop

Focused Clinical Question: What are the indications and clinical applications for gingival augmentation procedures, and what factors guide the choice among treatment options in specific situations? Summary: Although there is still controversy regarding whether there needs to be a minimum amount of attached gingiva to maintain the stability of the gingival margin, prospective and retrospective studies have shown that, in the presence of suboptimal plaque control and clinical inflammation, attachment loss and gingival recession (GR) may result unless a minimum amount of keratinized tissue (KT) and attached gingiva are present. Treatment of mucogingival deformities requires gingival augmentation procedures that address both a functional and esthetic component for the patient. Although free gingival grafts (FGGs) are considered the gold standard for treatment of GR defects to obtain root coverage, augmentation of KT and attached gingiva may be accomplished by FGG or other autogenous grafting options, including the free connective tissue graft, the lateral pedicle graft, and the double papilla technique. In addition, the modified apically repositioned flap can be considered in some instances. Alternatives to autogenous graft tissue include acellular dermal matrix, extracellular matrix membrane, bilayer collagen matrix, and living cellular construct. Conclusions: Understanding the clinical importance of the presence of a minimum amount of attached gingiva in patients with suboptimal hygiene is an important first step in addressing the condition. Patient education to address plaque control and counseling to quit smoking in patients who are smokers help enhance the success of these mucogingival surgical procedures. An analysis of patient-specific factors will help with the appropriate choice of surgical procedures aimed at augmenting the dimension of KT/attached gingival tissue. Evidence supporting the treatment decisions described in this practical application is summarized in the companion papers from the American Academy of Periodontology Regeneration Workshop (Kim and Neiva, J Periodontol 2015;86(Suppl.):S56-S72; Scheyer et al., J Periodontol 2015;86(Suppl.):S73-S76).

Implant associated soft tissue defects in the anterior maxilla: a randomized control trial comparing subepithelial connective tissue graft and acellular dermal matrix allograft

INTRODUCTION

This randomized controlled clinical pilot trial compared the efficacy of 2 soft tissue grafting methods for correcting esthetic discrepancies associated with definitively restored implant crowns.

METHODS

Thirteen patients presenting with implants displaying recession, thin biotype, concavity defects, or a combination thereof associated with single crowned dental implants randomly received subepithelial connective tissue grafts (SCTG) in the control group (N = 7) or acellular dermal matrix (ADM) allografts in the test group (N = 6), both under coronally positioned flaps. Data regarding soft tissue, hard tissue, esthetics, and quality of life (QoL) parameters were collected over 6 months.

RESULTS

Both groups gained tissue thickness (SCTG: 63% and ADM: 105%), reduced concavity measures (SCTG: 82% and ADM: 96%), and improved recessions (SCTG: 40% and ADM: 28%) from baseline to 6 months. Clinicians determined improvement in esthetics for both groups (P = 0.001), unlike patients who did not change their esthetic ratings. No statistical differences were noted for QoL assessment; however, ADM subjects had more eventful wound healing (P = 0.021).

CONCLUSIONS

Within the limitations of this study, both SCTG and ADM result in increased mucosal thickness, reduction in concavity dimensions, and have a potential for recession reduction on definitively restored dental implants.