Soft tissue volume augmentation at dental implant sites using a volume stable three-dimensional collagen matrix - histological outcomes of a preclinical study

Alveolar Ridge Preservation With Fibro-Gide or Connective Tissue Graft: A Randomized Controlled Trial of Soft and Hard Tissue Changes

OBJECTIVE

The aim of this study was to evaluate the effectiveness of a novel biomaterial (FG) for alveolar ridge preservation compared to CTG in terms of soft tissue thickness and bone dimensional changes.

MATERIALS AND METHODS

A randomized clinical trial was conducted on 30 patients who required extraction of 30 hopeless mandibular posterior teeth. All patients went through atraumatic tooth extraction, and then, they were randomly allocated to either a CTG, an FG, or a spontaneous healing (SH) group (1:1:1). All patients received a dental implant placed 6 months postoperatively. The soft tissue thickness and bone dimensional changes were measured before and 6 months after the procedure.

RESULTS

The study's analysis revealed statistically significant differences in buccal gingival thickness and dimensional bone changes across the three examined groups after 6 months (p < 0.05). The SH group had lower gingival thickness (1.31 ± 0.65 mm) and higher vertical resorption (-1.46 ± 1.67 mm at the buccal aspect) compared with the CTG and FG groups. The CTG and FG groups had similar gingival thickness (2.42 ± 0.70 and 3.00 ± 0.71 mm, respectively) and bone width reduction (+0.86 ± 2.31 and +0.93 ± 2.38 mm, respectively), whereas the CTG group had lower vertical bone loss (-0.30 ± 1.09 mm at the buccal aspect) than the FG group (-0.47 ± 2.30 mm at the buccal aspect).

CONCLUSION

FG and CTG demonstrate equivalent soft tissue thickness and comparable horizontal bone dimension outcomes in ARP.

Evaluation of Porcine-Derived Collagen Membranes for Soft Tissue Augmentation in the Oral Cavity: An In Vivo Study

The use of porcine-derived collagen membranes (PDCM) to improve intraoral soft tissue rehabilitation remains under investigation. Different degrees of crosslinking have yielded differences in resorption time and inflammation surrounding collagen membranes. The aim of this study was to evaluate the in vivo performance of bilayered PDCMs with varying degrees of crosslinking for the regeneration of oral soft tissue defects. Bilateral split-thickness oral mucosa defects were created in mandibles of beagles (n=17) and assigned to one of the following: bilayer PDCM (high crosslinking porcine dermis in sheet form-H-xlink) and (low crosslinking porcine dermis in sheet form-L-xlink), bilayer PDCM (non-crosslinked predicate collagen membrane in spongy form-Ctrl), or negative control (Sham) and compared with positive control (unoperated). Animals were euthanized after 4-, 8-, or 12-weeks of healing to evaluate soft tissue regeneration and remodeling through histomorphometric analyses. H-xlink membranes presented delayed healing with a poorly developed epithelial layer (analogous to the sham group) across time points. Relative to Ctrl at 8 and 12 weeks, defects treated with H-xlink presented no difference in semiquantitative scores ( P > 0.05), while L-xlink exhibited greater healing ( P = 0.042, P = 0.043, at 8 and 12 weeks, respectively). Relative to positive control, L-xlink exhibited similar healing at 8 weeks and greater healing at 12 weeks ( P = 0.037) with a well-developed epithelial layer. Overall, groups treated with L-xlink presented with greater healing relative to the positive control after 12 weeks of healing and may serve as an alternative to autologous grafts for intraoral soft tissue regeneration.

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.

Effects of implant placement timing and type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical canine model

AIM

To determine the effects of implant timing and type of soft-tissue grafting on histological and histomorphometric outcomes in a preclinical model.

MATERIALS AND METHODS

Four implant placement protocols were randomly applied at the mesial root sites of the third and fourth mandibular premolars in 10 mongrel dogs: immediate placement (group IP), early placement (group EP), delayed placement with/without alveolar ridge preservation (groups ARP and DP, respectively). A connective-tissue graft (CTG) or porcine-derived volume-stable collagen matrix (VCMX) was applied to enhance the ridge profile (simultaneously with implant placement in group IP and staged for others), resulting in five sites for each combination. All dogs were sacrificed 3 months after soft-tissue grafting. Histological and histomorphometric analyses were performed, and the data were analysed descriptively.

RESULTS

CTG and VCMX were difficult to differentiate from the augmented area. The median total tissue thickness on the buccal aspect of the implant was largest in group IP/CTG (between 2.78 and 3.87 mm). The soft-tissue thickness was generally favourable with CTG at all implant placement timings. Within the DP groups, CTG yielded statistically significantly larger total and soft-tissue thickness than VCMX (p < .05). Among the groups with VCMX, group EP/VCMX showed the largest soft-tissue thickness at apical levels to the implant shoulder.

CONCLUSIONS

CTG generally led to greater tissue thickness than VCMX.

Ridge preservation using a self-retaining block type bone substitute for extraction sockets with buccal dehiscence defects - A preclinical study

OBJECTIVE

To evaluate the effect of a self-retaining block-type bone substitute (srBB) on the dimensional stability of the horizontal ridge width at the coronal level in a buccal dehiscence model.

MATERIALS AND METHODS

Four box-shaped bone defects with a buccal dehiscence were surgically prepared in the partially edentulous mandible (n = 6). Experimental biomaterials were randomly assigned to each site: (1) Control group: no treatment, (2) particle-type bone substitute (PBS) group, (3) collagenated soft block bone substitute (csBB) group, and (4) self-retaining synthetic block bone (srBB) group. In all grafted groups, a collagen membrane covered the biomaterials. At 16 weeks, clinical, histological, and radiographic analyses were performed.

RESULTS

Three of the six blocks in the srBB group became exposed and fell out during the first week after surgery. Therefore, the remaining three specimens were renamed RsrBB group. The RsrBB group showed an increase horizontal ridge compared to the pristine bone width at 2-4 mm below the CEJ, while the other groups showed resorption (augmented width at 2 mm below: 4.2, 42.4, 36.2, and 110.1% in the control, PBS, csBB, and RsrBB groups, respectively). The mineralized bone area was largest in the RsrBB group (4.74, 3.44, 5.67, and 7.77 mm2 in the control, PBS, csBB, and RsrBB groups, respectively.).

CONCLUSIONS

The srBB group demonstrated the highest volume stability at the coronal level. These findings would potentially suggest that self-retaining block bone substitute might be a good candidate for alveolar ridge preservation.

Surface topography of resorbable porcine collagen membranes, and their effect on early osteogenesis: An in vitro study

OBJECTIVE

Guided tissue regeneration (GTR) is based on the use of different membranes that function as sealants and barriers in specific clinical situations. Among the several tissue production methods and origins, resorbable porcine-derived membranes are the most commonly used. Because these membranes are so diverse, and have several different clinical applications, doubts linger as to their effect in stimulating osteogenesis. The objective of this study was to make an in vitro evaluation of the viability and differentiation of osteoblastic cells cultured on the surface of the following collagen membranes: Jason® (Botiss Biomaterials), Collprotect® (Botiss Biomaterials), and Bio-Gide® (Geistlich).

MATERIAL AND METHODS

Fragments of the 3 resorbable collagen membranes (5 × 5 mm) were used, and pre-osteoblastic SAOS-2 cells (ATCC, USA) were plated on their porous surfaces. Evaluation of the membranes was performed at 3, 5 and 7 days, considering the following parameters: (1) topographic analysis of the different surfaces by scanning electron microscope; (2) cellular viability by MTT, (3) quantification of type I collagen and osteopontin by Elisa. The quantitative analyses were carried out using a significance level of 5%.

RESULTS

Collprotect® and Jason® membranes presented a rough surface with an irregular aspect on both sides, while double-layered Bio-Gide® had one layer with a smooth surface and the other with a rough surface along each respective length. The viability assays revealed that the cells cultured the cells grown on Collprotect® showed higher viability than those grown in Bio-Gide® or Jason®, especially after 5 and 7 days. After 3 and 5 days, evaluation of type I collagen showed that the cells plated on the Jason® and Collprotect® surfaces had greater collagen secretion than those plated on BioGide®. After 7 days, an increase in osteopontin levels was observed when the cells were plated on all the experimental membranes, compared with the control group.

CONCLUSION

All the tested membranes were suitable for use in GTR clinical procedures. Their indication in specific regenerative cases depends on the mechanical and biological properties of their originating tissues, thus enabling better results and assertive choices by dental professionals.

Properties of three collagen scaffolds in comparison with native connective tissue: an in-vitro study

PURPOSE

To evaluate collagen scaffolds (CS) in terms of their in vitro resorption behavior, surface structure, swelling behavior, and mechanical properties in physiologically simulated environments, compared with porcine native connective tissue.

MATERIALS AND METHODS

Three test materials-one porcine collagen matrix (p-CM), two acellular dermal matrices (porcine = p-ADM, allogenic = a-ADM)-and porcine native connective tissue (p-CTG) as a control material were examined for resorption in four solutions using a high-precision scale. The solutions were artificial saliva (AS) and simulated body fluid (SBF), both with and without collagenase (0.5 U/ml at 37 °C). In addition, the surface structures of CS were analyzed using a scanning electron microscope (SEM) before and after exposure to AS or SBF. The swelling behavior of CS was evaluated by measuring volume change and liquid absorption capacity in phosphate-buffered saline (PBS). Finally, the mechanical properties of CS and p-CTG were investigated using cyclic compression testing in PBS.

RESULTS

Solutions containing collagenase demonstrated high resorption rates with significant differences (p < 0.04) between the tested materials after 4 h, 8 h and 24 h, ranging from 54.1 to 100% after 24 h. SEM images revealed cross-linked collagen structures in all untreated specimens. Unlike a-ADM, the scaffolds of p-CM and p-ADM displayed a flake-like structure. The swelling ratio and fluid absorption capacity per area ranged from 13.4 to 25.5% among the test materials and showed following pattern: p-CM > a-ADM > p-ADM. P-CM exhibited higher elastic properties than p-ADM, whereas a-ADM, like p-CTG, were barely compressible and lost structural integrity under increasing pressure.

CONCLUSIONS AND CLINICAL IMPLICATIONS

Collagen scaffolds vary significantly in their physical properties, such as resorption and swelling behavior and elastic properties, depending on their microstructure and composition. When clinically applied, these differences should be taken into consideration to achieve the desired outcomes.

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.

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

OBJECTIVE

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.

MATERIALS AND METHODS

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).

RESULTS

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).

CONCLUSION

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.

The efficacy of a porcine collagen matrix in keratinized mucosa width augmentation: a 10-year follow-up clinical prospective study

PURPOSE

The aim of the present study was to evaluate the long-term effectiveness of a xenogeneic collagen matrix (CM) in pre-prosthetic augmentation of the keratinized mucosa width (KMW) at implant sites.

METHODS

All of the patients with localized implant-supported rehabilitation previously treated with vestibuloplasty and KMW augmentation with a non-cross-linked porcine CM were recalled. KMW was measured clinically in an apico-coronal direction from the mucogingival junction to the mucosal margin at the prosthetic zenith of each crown. Measurements were performed clinically by means of a PCP-UNC15 periodontal probe and rounded to the nearest mm. KMW values recorded at 1 year, 5 and 10 years from the soft tissue augmentation procedure were compared using a one-way repeated-measures ANOVA with Bonferroni multiple comparison post-hoc analysis. The level of significance was set at 0.05.

RESULTS

Measurements were conducted on 13 patients. All implants were in function with no signs of biological complications. All except one implant site showed KMW ≥ 2 mm. KMW decreased significantly from 1 year (3.33 ± 1.11 mm) to 5 years (2.77 ± 0.92 mm) (p = 0.001), and finally remained stable from 5 to 10 years (3.2 ± 0.99 mm) (p = 0.607). From a visual aspect, peri-implant soft tissues were characterized by a good texture and color blending compared to the adjacent teeth, highlighting good integration of the remodeled tissues and stability of the esthetic result.

CONCLUSIONS

The use of a CM in pre-prosthetic soft tissue augmentation at implant sites has proven to be effective in obtaining and maintaining at least 2 mm of KMW around dental implants over a follow-up of 10 years.

Gingival biotype modification with collagen matrix or autogenous subepithelial connective tissue graft: Histologic and volumetric analyses in a beagle model

Objectives

To evaluate the volumetric effect and biocompatibility of porcine tendon-derived type I collagen matrix graft (CG) in gingival biotype modification (GBM) compared with subepithelial connective tissue graft (SCTG) in a beagle model.

Methods

Surface analysis using scanning electron microscopy and a collagen degradation assay of CG was performed in vitro. Six adult dogs were used in in vivo experiment, and each received autologous SCTG or CG at the anterior side. Histometric and three-dimensional digital volume analyses were conducted to compare quantitative changes in CG and SCTG in GBM. Immunohistochemical analysis was performed for the qualitative evaluation of CG compared to SCTG.

Results

CG had a double-layered structure, and its degradation was slower than that of other well-reported materials. No critical problems were associated with the healing procedure. Changes in gingival thickness and volume in the CG and SCTG groups were equivalent, with no significant differences between the groups. Type I collagen and vascular endothelial growth factor expression levels were similar in both groups.

Significance

CG and SCTG had equivalent potential for GBM in terms of quantity and quality. Additionally, CG could be used as a reasonable substitute for SCTG, making surgery convenient and predicting successful clinical outcomes.

Soft tissue esthetics around immediately provisionalized delayed implants with and without connective tissue graft: A randomized clinical trial pilot study

OBJECTIVE

Evaluate the peri-implant soft tissue esthetics following a single, immediately provisionalized, delayed implant with/-out subepithelial connective tissue graft (SCTG).

MATERIAL AND METHODS

The eligible patients were randomized into two groups. Immediate provisionalization was performed with (test group: SCTGG) or without SCTG (control group: NGG). The soft tissue esthetics was assessed by Pink Esthetic Score (PES) and Mucosal Scarring Index (MSI), at 6 and 12 months, following final implant restoration.

RESULTS

The SCTGG, compared to NGG, yielded a 0.2 increased PES at 12 months (95% confidence interval (CI): -1, 1.4) and a 0.2 decreased MSI score (95% CI -0.9, 0.5) with no statistically significant differences in PES and MSI between both groups (p > 0.05).

CONCLUSION

Soft tissue grafting around immediately provisionalized delayed implants could exhibit comparable results to immediate provisionalization alone in terms of peri-implant soft tissue esthetics using PES and MSI (ClinicalTrials.gov Identifier: NCT03770975).

Clinical and patient-reported outcomes of tissue engineering strategies for periodontal and peri-implant reconstruction

Scientific advancements in biomaterials, cellular therapies, and growth factors have brought new therapeutic options for periodontal and peri-implant reconstructive procedures. These tissue engineering strategies involve the enrichment of scaffolds with living cells or signaling molecules and aim at mimicking the cascades of wound healing events and the clinical outcomes of conventional autogenous grafts, without the need for donor tissue. Several tissue engineering strategies have been explored over the years for a variety of clinical scenarios, including periodontal regeneration, treatment of gingival recessions/mucogingival conditions, alveolar ridge preservation, bone augmentation procedures, sinus floor elevation, and peri-implant bone regeneration therapies. The goal of this article was to review the tissue engineering strategies that have been performed for periodontal and peri-implant reconstruction and implant site development, and to evaluate their safety, invasiveness, efficacy, and patient-reported outcomes. A detailed systematic search was conducted to identify eligible randomized controlled trials reporting the outcomes of tissue engineering strategies utilized for the aforementioned indications. A total of 128 trials were ultimately included in this review for a detailed qualitative analysis. Commonly performed tissue engineering strategies involved scaffolds enriched with mesenchymal or somatic cells (cell-based tissue engineering strategies), or more often scaffolds loaded with signaling molecules/growth factors (signaling molecule-based tissue engineering strategies). These approaches were found to be safe when utilized for periodontal and peri-implant reconstruction therapies and implant site development. Tissue engineering strategies demonstrated either similar or superior clinical outcomes than conventional approaches for the treatment of infrabony and furcation defects, alveolar ridge preservation, and sinus floor augmentation. Tissue engineering strategies can promote higher root coverage, keratinized tissue width, and gingival thickness gain than scaffolds alone can, and they can often obtain similar mean root coverage compared with autogenous grafts. There is some evidence suggesting that tissue engineering strategies can have a positive effect on patient morbidity, their preference, esthetics, and quality of life when utilized for the treatment of mucogingival deformities. Similarly, tissue engineering strategies can reduce the invasiveness and complications of autogenous graft-based staged bone augmentation. More studies incorporating patient-reported outcomes are needed to understand the cost-benefits of tissue engineering strategies compared with traditional treatments.

Recombinant human platelet-derived growth factor improves root coverage of a collagen matrix for multiple adjacent gingival recessions: A triple-blinded, randomized, placebo-controlled trial

AIM

To evaluate the efficacy of recombinant human platelet-derived growth factor (rhPDGF)-BB combined with a cross-linked collagen matrix (CCM) for the treatment of multiple adjacent gingival recession type 1 defects (MAGRs) in combination with the coronally advanced flap (CAF).

MATERIALS AND METHODS

Thirty patients were enrolled in this triple-blind, randomized, placebo-controlled trial and treated with either CAF + CCM + rhPDGF, or CAF + CCM + saline. The primary outcome was mean root coverage (mRC) at 6 months. Complete root coverage, gain in gingival thickness (GT), keratinized tissue width, volumetric and ultrasonographic changes, and patient-reported outcome measures were also assessed. Mixed-modelling regression analyses were used for statistical comparisons.

RESULTS

At 6 months, the mRC of the CCM + rhPDGF and CCM alone groups were 88.25% and 77.72%, respectively (p = .02). A significant gain in GT was consistently observed for both treatment arms, and more so for the patients receiving the matrix containing rhPDGF through time (0.51 vs. 0.80 mm, on average, p = .01). The rhPDGF + CCM treated patients presented greater volume gain, higher soft tissue thickness, and a superior aesthetic score.

CONCLUSION

rhPDGF enhances the clinical, volumetric, and aesthetic outcomes of MAGRs above the results achieved with CAF + CCM alone (ClinicalTrials.gov NCT04462237).

A multi-centre randomized controlled trial comparing connective tissue graft with collagen matrix to increase soft tissue thickness at the buccal aspect of single implants: 1-year results

AIM

To compare connective tissue graft (CTG) with collagen matrix (CMX) in terms of increase in buccal soft tissue profile (BSP) at 1 year when applied at single implant sites.

MATERIALS AND METHODS

Patients with a single tooth gap in the anterior maxilla and horizontal mucosa defect were enrolled in a multi-centre RCT. All sites had a bucco-palatal bone dimension of at least 6 mm, 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. The primary outcome was the increase in BSP at 1 year when compared to the pre-operative situation based on superimposed digital surface models. The changes in BSP over time were registered at a buccal area of interest reaching from 0.5 mm below the soft tissue margin to 4 mm more apical. Secondary outcomes included patient-reported, clinical and aesthetic outcomes.

RESULTS

Thirty patients were included per group (control: 50% females, mean age 50.1; test: 53% females, mean age 48.2). The increase in BSP at 1 year was 0.98 mm (98.3% CI: 0.75 - 1.20) for CTG and 0.57 mm (98.3% CI: 0.34 - 0.79) for CMX. The mean difference of 0.41 mm (98.3% CI: 0.12 - 0.69) in favour of CTG was significant (p < 0.001). Based on an arbitrarily chosen threshold for success of 0.75 mm increase in BSP, 89.7% of the patients in the control group and 10% of the patients in the test group were successfully treated (OR = 77.90; 95% CI 13.52 - 448.80; p < 0.001). Sites treated with CMX demonstrated 0.89 mm (98.3% CI: 0.49 - 1.30) more shrinkage between postop and 1 year than sites treated with CTG. In addition, CMX resulted in significantly more marginal bone loss (0.39 mm; 95% CI 0.05- 0.74; p = 0.026) than CTG. There were no significant differences between the groups in terms of patients' aesthetic satisfaction (p = 0.938), probing depth (p = 0.917), plaque (p = 0.354), bleeding on probing (p = 0.783), midfacial recession (p = 0.915), Pink Esthetic Score (p = 0.121) and Mucosal Scarring Index (p = 0.965).

CONCLUSION

CTG remains the gold standard to increase soft tissue thickness at implant sites. Clinicians need to outweigh the benefits of CMX against considerable resorption of the graft.

Use of Xenogenic Collagen Matrices in Peri-Implant Soft Tissue Volume Augmentation: A Critical Review on the Current Evidence and New Technique Presentation

Plastic peri-implant surgical procedures aiming to increase soft tissue volume around dental implants have long been well-described. These are represented by: pedicle soft tissue grafts (rotational flap procedures and advanced flap procedures) and free soft tissue grafts (epithelialized, also called free gingival graft (FGG), and non-epithelialized, also called, connective tissue graft (CTG) or a combination of both. To bypass the drawback connected with autologous grafts harvesting, xenogenic collagen matrices (XCM)s and collagen-based matrices derived from porcine dermis (PDXCM)s have been introduced, as an alternative, in plastic peri-implant procedures. Aim: This review is aimed to evaluate and to critically analyze the available evidence on the effectiveness of XCMs and PDXCMs in soft tissue volume augmentation around dental implants. Moreover, a clinical case with a new soft tissue grafting procedure technique (Guided Soft Tissue Regeneration, GSTR) is presented. Material and Methods: An electronic search was performed on the MEDLINE database, SCOPUS, Cochrane Library and Web of Science. The electronic search provided a total of 133 articles. One hundred and twenty-eight not meeting the inclusion criteria were excluded. Seven articles of human randomized clinical trials were selected. A total number of 108 patients were treated with CTG, and 110 patients with XCM. Results: in peri-implant soft tissue augmentation procedures, XCMs seem an effective alternative to CTGs, associated with lower patient morbidity and lower operative times.

Dimensional ridge changes in conjunction with four implant timing protocols and two types of soft tissue grafts: A pilot pre-clinical study

AIM

To determine the effect of (1) implant placement timing and (2) the type of soft tissue graft in terms of ridge profile changes.

MATERIALS AND METHODS

Four implant treatment modalities were applied in the mesial root areas of the third and fourth mandibular premolars of 10 mongrel dogs alongside connective-tissue graft (CTG) and volume-stable cross-linked collagen matrix (VCMX): immediate, early, and delayed placement (DP), and DP following alveolar ridge preservation (ARP). All dogs were sacrificed 3 months after soft tissue augmentation. Standard Tessellation Language files from designated time points were analysed.

RESULTS

Compared with the pre-extraction situation, the median width of the ridge demontstrated a linear increase only in group ARP/CTG (0.07 mm at the 2-mm level), whereas all other groups showed a reduction (between -1.87 and -0.09 mm, p > .05). Groups ARP/CTG (0.17 mm) and DP/CTG (0.05 mm) exhibited a profilometric tissue gain in a set region of interest (p > .05). The net effect of CTG and VCMX ranged from 0.14 to 0.79 mm.

CONCLUSIONS

Dimensional ridge changes varied between treatment protocols. ARP with CTG led to the smallest difference in ridge profile between the pre-extraction and the study end time point. Both CTG and VCMX enhanced the ridge contour.

Esthetic complications in implant dentistry

Esthetic complications in implant dentistry have become a significant consideration for patients and practitioners. This review presents an appraisal on the current knowledge of the physiological peri-implant soft-tissue dimensions and factors that may compromise peri-implant tissue esthetics. Factors such as papilla fill adjacent to the implant and midfacial mucosal height are critical parameters that determine the esthetic success of implant-supported restorations. Papilla fill adjacent to a single dental implant appears to depend upon the clinical attachment level of the neighboring tooth. A horizontal inter-implant distance of at least 3 mm is necessary to ensure optimal interproximal mucosal embrasure between two adjacent implants in the anterior maxilla. In cases where implants cannot be placed at least 3 mm apart, a single implant with a cantilever bridge should be considered. Buccolingual implant positioning plays a major role in midfacial mucosal height. Soft-tissue volume grafting following immediate implant placement in the presence of a thin soft-tissue phenotype or simultaneous to surgical peri-implantitis therapy might help to overcome facial mucosa recession.

Polymeric Scaffolds for Dental, Oral, and Craniofacial Regenerative Medicine

Dental, oral, and craniofacial (DOC) regenerative medicine aims to repair or regenerate DOC tissues including teeth, dental pulp, periodontal tissues, salivary gland, temporomandibular joint (TMJ), hard (bone, cartilage), and soft (muscle, nerve, skin) tissues of the craniofacial complex. Polymeric materials have a broad range of applications in biomedical engineering and regenerative medicine functioning as tissue engineering scaffolds, carriers for cell-based therapies, and biomedical devices for delivery of drugs and biologics. The focus of this review is to discuss the properties and clinical indications of polymeric scaffold materials and extracellular matrix technologies for DOC regenerative medicine. More specifically, this review outlines the key properties, advantages and drawbacks of natural polymers including alginate, cellulose, chitosan, silk, collagen, gelatin, fibrin, laminin, decellularized extracellular matrix, and hyaluronic acid, as well as synthetic polymers including polylactic acid (PLA), polyglycolic acid (PGA), polycaprolactone (PCL), poly (ethylene glycol) (PEG), and Zwitterionic polymers. This review highlights key clinical applications of polymeric scaffolding materials to repair and/or regenerate various DOC tissues. Particularly, polymeric materials used in clinical procedures are discussed including alveolar ridge preservation, vertical and horizontal ridge augmentation, maxillary sinus augmentation, TMJ reconstruction, periodontal regeneration, periodontal/peri-implant plastic surgery, regenerative endodontics. In addition, polymeric scaffolds application in whole tooth and salivary gland regeneration are discussed.

A multi-centre randomized controlled trial comparing connective tissue graft with collagen matrix to increase soft tissue thickness at the buccal aspect of single implants: 3-month results

AIM

To compare connective tissue graft (CTG) with collagen matrix (CMX) in terms of changes over time in buccal soft tissue profile (BSP) when applied at single implant sites.

MATERIALS AND METHODS

Patients with a single tooth gap in the anterior maxilla and horizontal mucosa defect were enrolled in a multi-centre randomized controlled trial. All sites had a bucco-palatal bone dimension of at least 6 mm and received a single implant and immediate implant restoration using a full digital workflow. Sites were randomly allocated to the control (CTG) or test group (CMX: Geistlich Fibro-Gide®, Geistlich Pharma AG, Wolhusen, Switzerland) to increase buccal soft tissue thickness. Primary outcome was increase in BSP at T1 (immediately after operation) and T2 (3 months) based on superimposed digital surface models. Secondary parameters included patient-reported clinical and aesthetic outcomes.

RESULTS

Thirty patients were included per group (control: 50% females, mean age 50; test: 53% females, mean age 48). Even though surgeons applied thicker grafts when using CMX, sites treated with CMX demonstrated 0.78 mm (95% CI 0.41-1.14) more shrinkage between T1 and T2 than sites treated with CTG. The final increase in BSP was 1.15 mm (95% CI 0.88-1.43) for CTG and 0.85 mm (95% CI 0.58-1.13) for CMX. The mean difference of 0.30 mm (95% CI -0.01 to 0.61) at T2 in favour of CTG was of borderline significance (p = .054). There were no significant differences between the groups in terms of post-operative bleeding (p = .344), pain (p = .331), number of analgesics taken (p = .504), oedema (p = .227), and pink aesthetic score (p = .655). VAS for post-operative haematoma was 6.56 (95% CI 0.54-12.59) lower for CMX, and surgery time could be reduced by 9.03 min (95% CI 7.04-11.03) when applying CMX. However, CMX resulted in significantly more marginal bone loss (0.38 mm; 95% CI 0.15-0.60), deeper pockets (0.30 mm; 95% CI 0.06-0.54), and more mid-facial recession (0.75 mm; 95% CI 0.39-1.12) than CTG.

CONCLUSIONS

CTG remains the gold standard for increasing soft tissue thickness at the buccal aspect of implants.

Design of customized soft-tissue substitutes for posterior single-tooth defects: A proof-of-concept in-vitro study

OBJECTIVES

Soft-tissue volume augmentation treatments do not provide the satisfactory long-term functional and esthetic outcomes. The aim of the study was to develop a standardized digital procedure to design individual soft-tissue substitutes (STS) and apply mathematical modeling to obtain average shape STS for single posterior tooth defects.

MATERIAL AND METHODS

Thirty-three casts from 30 patients were scanned. STS were designed with a computer-aided design software and a systematic procedure standardized the measurements across all STS using 3D-analysis software. The occlusal, mesial-distal, and buccal-lingual planes were defined to partition, each STS and produce a mesh. The thickness values of each 3D slice were documented in a coordinate system chart to generate a scatter graph. Graphs were embedded into images (Orange software) and images were analyzed via hierarchical clustering.

RESULTS

Three STS groups were identified according to shape. Two shapes corresponded to the maxilla defects: a square (n = 13) with dimensions of 10 mm in a lingual-buccal (length) and 7-10 mm in a mesial-distal (width) direction; a rectangle (n = 11) of 11 mm in length and 4-7 mm in width. The average shape for mandible defects (n = 9) was smaller (6-8 mm in length, 5-10 mm in width). The highest thickness in all STS was in the buccal portion, above the alveolar ridge, with median values of 2 mm. The lowest thickness of 0.2 mm was at the edges.

CONCLUSIONS

The study developed novel methodology to design customized, as well as average shape STS for volume augmentation. Future STS harboring adapted geometry might increase volume augmentation efficiency and accuracy, while reducing surgical time.

Peri-implant tissue augmentation by volume-stable collagen matrix transplantation: a study of dog mandibles

The aim of this study was to investigate histologically the amount of peri-implant tissue augmentation after volume-stable porcine collagen matrix transplantation. Six male beagle dogs were used in the experiment. P2, P4, and M1 distal roots were extracted under general anesthesia. After 6 months, implants were placed in the same sites, and volume-stable porcine collagen matrix transplantation was performed. Impressions were taken at 1 and 2 weeks and at 1, 2, and 3 months after transplantation. The dogs were euthanized at 3 months, and their mandibles were removed and scanned using micro-computed tomography. Standard Triangulated Language data were also obtained. Using preoperative models as a reference, the data for all time points were compared, and changes in the thickness of the cross-section of the implant sites were measured. The model created at 3 months was then compared with the mandible data, and the thickness of collected peri-implant soft tissue was measured under optical microscopy. Increased thickness was found at some of the sites on the buccal side. Regarding the peri-implant soft tissue, the thickness of the measured sites on the buccal side was significantly increased at 3 months in the experimental group. Histological observations of the internal structures of the tissue in the experimental group revealed irregular collagen fibers and a remnant collagen matrix. Endogenous tissue was observed within the collagen matrix, indicating good fusion with the surrounding autologous tissue. These results suggest that volume-stable porcine collagen matrix transplantation promotes peri-implant tissue augmentation on the buccal side.

Impact of Cross-Linking of Collagen Matrices on Tissue Regeneration in a Rabbit Calvarial Bone Defect

The cross-linking of collagen matrices (Cl_CM) may provide volume-stable enhanced defect regeneration when compared to non-cross-linked matrices (Ncl_CM). The aim of the present study was to investigate the bone forming potential of collagen matrices (CMs) and the effects of cross-linking CMs in a rabbit calvaria defect model. (1) Empty controls (n = 6), (2) Ncl_CM (n = 8), and (3) Cl_CM (n = 8) were selected to be observed for the healing in 10 mm critical-sized calvarial bone defects. The potential for the bone as well as the connective tissue formation were evaluated by micro-CT and histomorphometry at three months post-surgery. There were no statistically significant differences in terms of new bone volume in the defects between the groups. However, the Cl_CM induced significantly greater fibrous tissue regeneration (5.29 ± 1.57 mm²) when compared to the controls (3.51 ± 0.93 mm²) by histomorphometry. The remnants of collagen fibers with immune cells, including macrophages and giant cells, were occasionally observed in the Cl_CM group but not in the Ncl_CM group. In conclusion, the cross-linking of collagen did not influence the potential for bone formation. Nevertheless, Cl_CM might be advantageous for the maintenance of fibrous tissue volume without disturbing bone formation in the defects.

Collagen-Based Matrices for Osteoconduction: A Preclinical In Vivo Study

The aim of this study was to evaluate the influence of additional hydroxyapatite (HA) in collagen-based matrices (CM) and membrane placement on bone formation in calvarial defects. Critical size defects in the calvaria of 16 New Zealand White Rabbits were randomly treated with CM or mineralized collagen-based matrices (mCM). Half of the sites were covered with a collagen membrane. Animals were euthanized after 12 weeks of healing. The samples were studied by micro-CT and histology. Newly formed lamellar bone was observed in all samples at the periphery of the defect. In the central areas, however, new bone composed of both woven and lamellar bone was embedded in the soft tissue. Samples treated with mCM showed more residual biomaterial and induced more small bony islands in the central areas of the defects than samples with CM. Nevertheless, a complete defect closure was not observed in any of the samples at 12 weeks. Membrane placement resulted in a decrease in bone density and height. Significant differences between the groups were revealed only between CM groups with and without membrane coverage for bone height in the central area of the defect. Neither mineralization of CM nor membrane placement improved the osteogenic capacity in this particular defect. Nevertheless, mineralisation influenced bone density without a membrane placement and bone volume underneath a membrane. CM may be used as a scaffold in bone regeneration procedures, without the need of a membrane coverage. Further preclinical studies are warrant to optimise the potential of mCM.

Treatment of multiple gingival recessions with xenogeneic acellular dermal matrix compared to connective tissue graft: a randomized split-mouth clinical trial

PURPOSE

The aim of this study was to compare the efficacy of the tunnel technique for root coverage using a new xenogeneic acellular dermal matrix vs. connective tissue grafting (CTG) for the treatment of multiple maxillary adjacent recessions (recession type 1) at 12 months postoperatively.

METHODS

This study enrolled 12 patients with at least 3 contiguous, bilateral, symmetrical maxillary gingival recessions (i.e., at least 6 recessions per patient). In total, 74 recessions were treated using the modified coronally advanced tunnel (MCAT) technique combined with a novel porcine-derived acellular dermal matrix (PADM) at 37 test sites or CTG at 37 control sites. The following clinical parameters were measured: recession height, clinical attachment level, width of keratinized tissue, probing depth, recession width, gingival thickness, mean root coverage (MRC), and complete root coverage (CRC). Comparisons between test and control groups were made for pain visual analog scale scores at 14 days.

RESULTS

At 12 months, the MCAT with PADM (test) yielded a statistically significant improvement in all clinical parameters studied. MRC was significantly higher on the control sides (80.6%±23.7%) than on the test sides (68.8%±23.4%). Similarly, CRC was 48.7%±6.8% on the control sides (CTG), in contrast to 24.3%±8.2% on the test sides (PADM). Statistically significant differences were observed in favor of the control sides for all clinical parameters studied. Nevertheless, the MCAT in adjunction with PADM was clearly superior at reducing mean and maximum patient-reported postoperative pain intensity and pain duration in the first week after surgery.

CONCLUSIONS

The use of PADM to treat multiple recessions improved clinical parameters at 12 months, but these outcomes were nevertheless poorer than those observed for CTG. However, PADM reduced morbidity, particularly the pain experienced by patients.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03162016.

Buccal Peri-Implant Soft Tissue Augmentation by Means of a Porcine Collagen Matrix: A Proof of Concept Technical Note

The quality and quantity of peri-implant soft tissues at the crestal portion of dental implants are important aspects to consider for a long-term successful implant-supported rehabilitation. Some relevant factors attributed to the implant health include mucosal thickness and keratinization. In this respect, many techniques and materials have been described to augment and improve buccal peri-implant soft tissues. Over the last few years, newly developed xenogeneic collagen matrices have been introduced in peri-implant plastic surgery to replace autogenous soft tissue grafts; however, data remain controversial so far. Thus, the purpose of the present report was to present a novel surgical technique conceived to augment buccal peri-implant soft tissues in combination with a volume-stable porcine collagen matrix. The rationale and the fundamental concepts that led to the use of a xenogeneic matrix to increase soft tissue volumes were also discussed.

Volumetric soft tissue alterations in the early healing phase after peri- implant soft tissue contour augmentation with a porcine collagen matrix versus the autologous connective tissue graft: A controlled clinical trial

AIM

This study evaluates the early volumetric changes after buccal soft tissue contour augmentation around implants with a porcine collagen matrix (CM) vs. the subepithelial connective tissue graft (SCTG) from the palate.

MATERIALS AND METHODS

14 patients were enrolled after early implant placement with simultaneous contour augmentation and persistent buccal tissue deficits. At implant exposure, buccal soft tissues were thickened with the CM (n = 7) or the SCTG (n = 7). Impressions were taken before and after surgery, after ten days, one, three and six months. Impressions were digitized and augmented regions 3D evaluated (soft tissue volume (mm³ , %)/thickness (mm)).

RESULTS

Volume increase (mm³ ) after 6 months was 19.56 ± 8.95 mm³ (CM) and 61.75 ± 52.69 mm³ (SCTG) (insignificant, p = .058). In percentage, this was a volume loss of the initially augmented soft tissue volume (100%) of 81.76% in the CM group and 56.39% in the SCTG group (6 months). The mean soft tissue thickness increase (mm) in the buccal contour after 6 months was 0.30 ± 0.16 mm (CM) and 0.80 ± 0.61 mm (SCTG) (insignificant, p = .071).

CONCLUSION

The early healing phase is associated with a significant volume loss of the soft tissues. The SCTG shows insignificant superiority compared to the CM.

Breaking the wave of peri-implantitis

Peri-implant diseases are prevalent with a weighted mean prevalence rate of 43% across Europe and 22% across South and North America. Although the main etiologic agent is bacterial biofilm, a myriad of factors influence the initiation and progression of the disease. Unfortunately, the treatment of peri-implant diseases is at best favorable in the short term with a high rate of persistent inflammation and recurrence. Therefore, it is sensible to consider and control all potential factors that may predispose an implant to peri-implant tissue inflammation in an attempt to avoid the disease. This paper reviews recent evidence on factors that may predispose implants to peri-implantitis and measures that can be taken to prevent it.

Changes in mucogingival junction after an apically positioned flap with collagen matrix at sites with or without previous guided bone regeneration: A prospective comparative cohort study

AIM

To assess changes in the position of the mucogingival junction (MGJ) after an apically positioned flap (APF) with collagen matrix performed at sites with or without previous guided bone regeneration (GBR).

MATERIALS AND METHODS

Dental implants were placed with or without GBR (group GBR or non-GBR) depending on the available ridge width in 30 patients with a limited width of keratinized mucosa (MGJ placed more coronally than the expected prosthetic margin). An apically positioned flap with collagen matrix was performed in both groups. Changes in the position of the MGJ from the day of an apically positioned flap up to 1, 3, and 12 months thereafter were assessed on digital scans (primary endpoint). Secondary endpoints were the width and thickness of the keratinized mucosa, and the position of the mucosal margin.

RESULTS

The position of the MGJ changed significantly from baseline to the first month, by 5.25 ± 2.10 and 4.40 ± 1.41 mm in groups GBR and non-GBR, respectively. Thereafter, the position remained stable in both groups up to 1 year (changes from baseline of 5.46 ± 2.28 and 4.58 ± 1.92 mm, respectively; p = .34). The position of the mucosal margin did not differ between groups GBR and non-GBR (-1.57 ± 2.04 and -1.75 ± 2.08 mm, respectively; p = .84), nor did the width of the keratinized mucosa (1.20 ± 1.03 and 0.99 ± 0.66 mm, p = .91) or its thickness (1.28 ± 0.44 and 1.40 ± 0.78 mm, p = .87).

CONCLUSION

Apically positioned flap combined with a collagen matrix results in a more apical position of the MGJ at sites with or without GBR. Following a coronal shift during the first month after the apical positioning of the flap, the level of the MGJ remained stable.

Augmentation of soft tissue volume at pontic sites: a comparison between a cross-linked and a non-cross-linked collagen matrix

AIM

To assess histopathological and histomorphometric outcomes of soft tissue volume augmentation procedures at pontic sites using a volume-stable cross-linked collagen matrix (VCMX) and a non-cross-linked collagen matrix (XCM).

MATERIALS AND METHODS

In twelve adult beagle dogs, the mandibular premolars and first molar were hemisected and the mesial root extracted. Soft tissue augmentation was randomly performed using VCMX, XCM, or a sham-operated control. Sacrifice was performed after 4, 8, and 26 weeks. Non-decalcified sections were analyzed for histopathologic and histomorphometric measurements at four different levels below the crest (1.5, 2.5, 3.5, and 5.5 mm).

RESULTS

Group VCMX presented a greater overall amount of soft tissue at all healing time points, more pronounced fibroblast ingrowth, vascularization, and a substantial new collagen deposition. Over time, group XCM demonstrated faster signs of degradation compared with group VCMX. Four weeks after augmentation, group VCMX yielded a higher mean ridge width compared with groups XCM (2.22 mm VCMX, 0.89 mm XCM (at 2.5 mm); 2.05 mm VCMX, 0.80 mm XCM (at 3.5 mm) p < 0.05) and sham (0.59 mm sham (at 1.5 mm); 0.48 mm (at 2.5 mm); 0.44 mm (at 3.5 mm) p < 0.05). After healing periods of 8 and 26 weeks, measurements in group VCMX remained significantly higher compared with group sham both at 8 weeks (levels of 1.5 mm, 2.5 mm and 5.5 mm) and at 26 weeks (levels of 1.5 mm, 3.5 mm and 5.5 mm) (p < 0.05).

CONCLUSION

The use of a cross-linked collagen matrix resulted in a greater and more stable ridge width over time compared with control groups.

CLINICAL RELEVANCE

Soft tissue volume augmentation at pontic sites is more effective when using a cross-linked compared with a non-cross-linked collagen matrix.

Effects of soft tissue grafting prior to orthodontic treatment on preventing gingival recession in dogs

PURPOSE

This study was conducted to assess the efficacy of prophylactic gingival grafting in the mandibular anterior labial area for preventing orthodontically induced gingival recession.

METHODS

Eight mongrel dogs received gingival graft surgery at the first (I1) and third (I3) mandibular incisors on both sides based on the following group allocation: AT group (autogenous connective tissue graft on I1), AT-control group (contralateral side in the AT group), CM group (xenogeneic cross-linked collagen matrix graft on I3) and CM-control group (contralateral side in the CM group). At 4 weeks after surgery, 6 incisors were splinted and proclined for 4 weeks, followed by 16 weeks of retention. At 24 weeks after surgery, casts were made and compared with those made before surgery, and radiographic and histomorphometric analyses were performed.

RESULTS

Despite the proclination of the incisal tip (by approximately 3 mm), labial gingival recession did not occur. The labial gingiva was thicker in the AT group (1.85±0.50 mm vs. 1.76±0.45 mm, P>0.05) and CM group (1.90±0.33 mm vs. 1.79±0.20 mm, P>0.05) than in their respective control groups.

CONCLUSIONS

The level of the labial gingival margin did not change following labial proclination of incisors in dogs. Both the AT and CM groups showed enhanced gingival thickness.

Tissue Response to a Porous Collagen Matrix Used for Soft Tissue Augmentation

A short inflammatory phase and fast ingrowth of blood vessels and mesenchymal cells are essential for tissue integration of a biomaterial. Macrophages play a key role in this process. We investigated invasion of macrophages, blood vessels, and proliferating cells into a highly porous and volume-stable collagen matrix (VCMX) used for soft tissue augmentation around teeth and dental implants. The biomaterial was implanted in submucosal pouches in the canine maxilla, and the tissue response was analyzed at six different time points. Immunohistochemistry was done for proliferating cells (PCNA), macrophages (MAC387), multinucleated giant cells (CD86), and blood vessels (TGM2). Blood rapidly filled the VCMX pores. During the first week, MAC387+ cells populated the VCMX pores, blood vessels and PCNA+ cells invaded the VCMX, and CD86+ scattered cells were observed. At 15 days, MAC387+ cells were scanty, blood vessels had completely invaded the VCMX, the number of proliferating cells peaked, and fibroblasts appeared. At 30 days, MAC387+ were absent, the numbers of proliferating and CD86+ cells had declined, while blood vessel and fibroblast numbers were high. At 90 days, residual VCMX was well-integrated in soft connective tissue. In conclusion, the VCMX elicited a short inflammatory phase followed by rapid tissue integration.

Gingiva thickening with a porcine collagen matrix in a preclinical dog model: Histological outcomes

AIM

To compare 10-month histological and immunohistological outcomes after soft tissue thickening around teeth with a porcine collagen matrix (CM) versus a subepithelial connective tissue graft (SCTG).

MATERIAL AND METHODS

In eight beagle dogs, soft tissue thickening of the buccal gingiva of upper canines was performed with the SCTG or the CM. Connective tissue thickness (CTT) was histomorphometrically measured in the augmented regions. The augmented connective tissues were also histologically characterized and the collagen I and vascular endothelial growth factor (VEGF) expressions immunohistologically quantified.

RESULTS

CTT significantly differed between groups (SCTG: 1.32 mm ± 0.44 mm; CM: 1.06 mm ± 0.27 mm; p = .008). Descriptive histological analyses revealed mature connective tissue that did not differ between groups. Immunohistological quantification of collagen I and VEGF expressions in the connective tissue also revealed no significant inter-group differences (collagen I: SCTG, 32.64% ± 7.09% vs. CM, 30.57% ± 7.83%; VEGF: SCTG, 39.06% ± 7.27% vs. CM, 37.15% ± 9.80%).

CONCLUSION

SCTG is superior to CM with regard to CTT in this experimental model. The CM and the SCTG lead to comparable connective tissue quality ten months after connective tissue thickening.

Treatment of peri-implant soft tissue defects: a narrative review

Soft tissue defects around dental implants, such as papilla or volume loss, peri-implant recession and alterations of the ridge color and/or texture, lead to esthetic and functional complaints. Treatments of these defects in implants are more demanding than in teeth because peri-implant tissue exhibits different anatomical and histological characteristics. This narrative review discusses the proposed treatments for soft tissue defects around implants in the current literature. Several clinical and pre-clinical studies addressed methods to augment the quantity of the peri-implant keratinized mucosa. Autogenous grafts performed better than soft tissue substitutes in the treatment of soft tissue defects, but there is no clinical consensus on the more appropriate donor area for connective tissue grafts. Treatment for facial volume loss, alterations on the mucosa color or texture and shallow peri-implant recessions are more predictable than deep recessions and sites that present loss of papilla. Correction of peri-implant soft tissue defects may be challenging, especially in areas that exhibit larger defects and interproximal loss. Therefore, the regeneration of soft and hard tissues during implant treatment is important to prevent the occurrence of these alterations.

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.

Soft tissue augmentation applying a collagenated porcine dermal matrix during second stage surgery: A prospective multicenter case series

BACKGROUND

The achievement and preservation of an adequate amount of soft tissue around implants is a critical factor for the prognosis of the treatment.

PURPOSE

To evaluate the effectiveness of a porcine dermal matrix applied during second stage implant surgery for horizontal soft tissue augmentation and preservation of dimensional stability.

MATERIALS AND METHODS

Twenty patients (mean age 50.2 ± 11.9 [SD] years) candidate to implant therapy and requiring soft tissue augmentation were recruited in four centers. Augmentation was performed in 24 cases. A porcine dermal matrix was placed into a buccal split-thickness pouch during uncovering surgery. Silicone impressions were taken before surgery (T0), 2 weeks later at suture removal (T2), 6 months (T3), and 24 months (T4) post augmentation. Dimensional changes of soft tissue were evaluated using superimposition of digitalized study casts.

RESULTS

Nineteen patients (23 implants) could be evaluated at 6 months and 13 patients (17 implants) at 24 months. After 6-month follow-up, there was a significant dimensional gain respect to baseline, averaging 0.83 ± 0.64 mm (P < .01). This did not change significantly at 24 months (0.77 ± 0.65 mm, P = .19). The gain was >0.5 mm in 65.2% and 64.7% of the cases, respectively. Soft tissue shrinkage averaged 34.2% ± 77.0% from T2 to T3 (P < .01) and did not change thereafter (P = .39). Shrinkage was more consistent in the posterior mandible than in the maxilla, but not significantly (P = .23 at 6-month and .36 at 24-month). No adverse events occurred.

CONCLUSION

Within the limitations of this prospective case series, the use of a porcine dermal matrix may provide consistent soft tissue augmentation that maintains up to 24-month follow-up, although graft shrinkage may occur in the first 6 months, depending on the location of surgery.

Increasing the tissue thickness at implant sites using guided bone regeneration and an additional collagen matrix: Histologic observations in beagle dogs

OBJECTIVES

To histologically determine the alteration in horizontal mucosal thickness at sites that received guided bone regeneration (GBR) with additional use of collagen matrix and to assess whether bone formation is affected by adding collagen matrix at GBR sites at 8 weeks of healing.

MATERIALS AND METHODS

Eight weeks after bilateral extraction of maxillary premolars, standardized defects were created on buccal side of edentulous ridges in four beagle dogs. One side was randomly allocated as control (biphasic calcium phosphate plus collagen membrane; GBR only), while contralateral side was allocated as test (biphasic calcium phosphate plus collagen membrane plus an additional layer of collagen matrix). Histologic observations, histomorphometric and micro-computed tomography analyses were performed after 8 weeks.

RESULTS

Membrane complex comprising residual collagen membrane and adjacent dense connective tissue was observed at both control and test sites. The thickness in the histologic analysis were 1.69 ± 0.23 mm (control) and 1.76 ± 0.07 mm (test) in histologic analysis and were 2.03 ± 0.26 mm (control) and 2.14 ± 0.24 mm (test) in radiographic analysis. The thickness of the membrane complex in soft-tissue layer were 723.0 ± 241.6 μm (control) and 984.6 ± 334.4 μm (test). The percentage of new bone formation were 22.30 ± 5.92% (control) and 25.50 ± 8.08% (test). All measured outcome did not show significant differences between control and test groups.

CONCLUSION

The addition of collagen matrix on top of standard GBR procedure did not increase the soft tissue thickness and dense connective tissue formation at 8 weeks of healing. Bone regeneration was not affected by the addition of collagen matrix. © 2018 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 107B: 741-749, 2019.

Xenogenic collagen matrix or autologous connective tissue graft as adjunct to coronally advanced flaps for coverage of multiple adjacent gingival recession: Randomized trial assessing non-inferiority in root coverage and superiority in oral health-related quality of life

Aim

To evaluate the non‐inferiority of the adjunct of a xenogeneic collagen matrix (CMX) or connective tissue graft (CTG) to coronally advanced flaps (CAF) for coverage of multiple adjacent recessions and compare superiority in patient‐reported outcomes (PROM).

Material and methods

One hundred and eighty‐seven subjects (92 CMX) with 485 recessions in 14 centres were randomized and followed up for 6 months. Patients filled daily diaries for 15 days to monitor patient‐reported experience. The primary outcome was changed in position of the gingival margin. Multilevel analysis used centre, subject and tooth as levels and baseline parameters as covariates.

Results

Average baseline recession was 2.5 ± 1.0 mm. The surgery was 15.7 min shorter (95%CI from 11.9 to 19.6, p < .0001) and perceived lighter (11.9 VAS units, 95%CI from 4.6 to 19.1, p = .0014) in CMX subjects. Time to recovery was 1.8 days shorter in CMX. Six‐month root coverage was 1.7 ± 1.1 mm for CMX and 2.1 ± 1.0 mm for CTG (difference of 0.44 mm, 95%CI from 0.25 to 0.63 mm). The upper limit of the confidence interval was over the non‐inferiority margin of 0.25 mm. Odds of complete root coverage were significantly higher for CTG (OR = 4.0, 95% CI 1.8–8.8).

Conclusion

Replacing CTG with CMX shortens time to recovery and decreases morbidity, but the tested generation of devices is probably inferior to autologous CTG in terms of root coverage. Significant variability in PROMs was observed among centres.

Randomized controlled clinical study comparing a volume-stable collagen matrix to autogenous connective tissue grafts for soft tissue augmentation at implant sites: linear volumetric soft tissue changes up to 3 months

AIM

To test whether or not the use of a volume-stable collagen matrix (VCMX) results in soft tissue volume increase at implant sites non-inferior to an autogenous subepithelial connective tissue graft (SCTG).

METHODS

In 20 patients, soft tissue augmentation at implant sites was performed using VCMX or SCTG. Casts obtained prior to augmentation (BL), at 30 (FU-30) and 90 days (FU-90) were digitized and transferred to stereolithography (STL) files. BL, FU-30 and FU-90 STL files were superimposed and linear volumetric changes evaluated in crestal and buccal regions of interest (ROI). Descriptive analysis was computed for both groups and a test for non-inferiority was performed.

RESULTS

The median linear changes from BL to FU-90 in the crestal ROI amounted to 0.175 mm (0.06; 0.51) for VCMX (p = 0.002 over time) and to 0.51 mm (0.23; 0.94) for SCTG (p = 0.129). The differences between the two groups were not significant (p = 0.287). The respective values in the buccal ROI were 0.59 mm (0.26; 1.06) for VCMX (p = 0.002) and 0.94 mm (0.66; 1.13) for SCTG (p = 0.004). The differences between the two groups were not significant (crestal: p = 0.287; buccal: p = 0.534). Non-inferiority could be concluded for VCMX compared to SCTG for both ROI.

CONCLUSION

VCMX and SCTG can be used for soft tissue augmentation at implant sites resulting in an at least short-term increase in volume.