Clinical comparison of a xenogeneic collagen matrix versus subepithelial autogenous connective tissue graft for augmentation of soft tissue around implants

Consensus Report by the Italian Academy of Osseointegration on the Importance of Peri-Implant Soft Tissues

Background and Objectives: The influence of the quantity and quality of peri-implant soft tissue on implant health and long-term maintenance is controversial. This consensus aimed to assess the importance of peri-implant soft tissue by analyzing four aspects: the role of keratinized mucosa (KM), the efficacy of specific collagen matrix, the influence of abutment material, and soft-tissue thickness. Materials and Methods: Active members of the Italian Academy of Osseointegration (IAO) participated in the consensus. Four systematic reviews were conducted, and their results were discussed to provide guidelines on the importance of soft tissue around implants. The first review evaluated the effect of KM on soft-tissue health, peri-implant bone loss, and patient-related variables. The second one analyzed if there was a specific type of matrix that provided better results in terms of peri-implant buccal soft-tissue thickness and keratinized mucosa width compared to autogenous soft-tissue graft. The third review evaluated the influence of different abutment materials on the soft tissues, and the fourth assessed the effect of soft-tissue thickness on peri-implant marginal bone loss (MBL). Results and Conclusions: The agreements reached by the assembly were as follows: the presence of supra-periosteal keratinized tissue is considered to favorably influence peri-implant health and aesthetics but had no relation to preventing bone crest resorption unrelated to infection. It facilitates patient cleaning around implants and reduces patient-reported pain. The free gingival graft (FGG) is considered the best in terms of supra-periosteal KM increase. Connective tissue grafts (CTG) perform better than volume-stable collagen matrices to increase soft-tissue thickness. Collagen matrices reduce surgical time and patient morbidity and can give better camouflaging. The influence of abutment material (titanium or zirconia) on MBL remains controversial, and no conclusion could be reached on this issue. Peri-implant soft-tissue health and recession seem not to be influenced by abutment material, but data are limited to zirconia and titanium. Although this systematic review highlighted the absence of a correlation between soft-tissue thickness and MBL, the assembly failed to find a consensus on this issue.

Soft Tissue Augmentation After Tooth Extraction Improves Implant Health: Findings From a Clinical Trial

Background Soft tissue augmentation is a critical procedure in dental implantology aimed at improving peri-implant health and aesthetics. Various materials are used for this purpose, but their comparative effectiveness remains under-researched. This study aimed to evaluate the effects of soft tissue augmentation utilizing two different materials after tooth extraction on peri-implant clinical and radiographic outcomes. Methodology A randomized controlled trial was conducted with 30 participants requiring extraction of non-restorable mandibular posterior teeth. Participants were randomly assigned to receive connective tissue graft (CTG), Fibro-gide (FG), or spontaneous healing (SH) in a 1:1:1 allocation ratio. Two months post-treatment, dental implants were placed. Six months after the functional loading of the dental implant, peri-implant health was assessed using the Plaque Accumulation Index, bleeding on probing (BOP), pocket depth, mucosal recession, and marginal bone level. Results At the six-month follow-up, the SH group exhibited significantly higher Plaque Index and BOP percentages (6.43 ± 1.23 and 70%, respectively) compared to the CTG group (0.40 ± 0.32 and 8.3%, respectively) and FG group (0.45 ± 0.44 and 9.7%, respectively). The mean probing pocket depth was also significantly higher in the control group (5.13 ± 0.64 mm), while the CTG and FG groups showed minimal changes (3.83 ± 0.39 mm for both groups). Additionally, gingival recession was higher in the control group (0.65 ± 0.18 mm) compared to the CTG and FG groups (0.03 ± 0.08 mm for both groups). Radiographic analysis revealed greater marginal bone loss in the control group (0.40 ± 0.05 mm) compared to the CTG and FG groups, which demonstrated minimal bone loss (0.17 ± 0.08 mm and 0.20 ± 0.00 mm, respectively). Conclusions The study findings indicate that FG is as effective as CTG in maintaining peri-implant health, outperforming SH. These findings suggest that FG can be a viable alternative to CTG in soft tissue augmentation after tooth extraction, offering a new option for clinicians in the management of extraction sites before dental implant placement.

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.

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.

A Novel Prehydrated Porcine-Derived Acellular Dermal Matrix: A Histological and Clinical Evaluation

It is well known that soft tissue quality and quantity around dental implants is of paramount importance for later peri-implant health. For this purpose, the clinical and histological outcomes of the peri-implant mucosa, following soft tissue augmentation for soft tissue improvement with a novel prehydrated porcine acellular dermal matrix graft (PPADMG) in conjunction with simultaneous implant placement, were evaluated in this case series. Twenty-two patients were included in the study. They underwent a late implant placement protocol combined with PPADMG for soft tissue augmentation. A punch biopsy was taken at the time of uncovery of the submerged healed implant after a mean of 157 days healing time. Supracrestal soft tissue height (STH) was measured at the time of implant placement and uncovery. All sites showed a clinical increase in STH. The histological structure of the biopsies resembled a similar structure as found in the healthy oral mucosa. No unexpected tissue reactions could be found. Within the limits of this clinical and histological study, it may be concluded that STH improvement with this novel porcine-derived acellular dermal matrix, in combination with simultaneous implant placement, is a viable option to create a peri-implant tissue thickness and stability.

The influence of connective tissue grafting on the reconstruction of a missing facial bone wall using immediate implant placement and simultaneous bone reconstruction: a retrospective long-term cohort study

PURPOSE

This retrospective cohort study evaluates the influence of connective tissue grafts (CTG) on bone regeneration at implant sites with total loss of the buccal bone wall treated with flapless immediate implant placement (IIP) and reconstruction with autogenous bone chips (AB) within a follow-up of up to 13 years.

METHODS

Sixty implants were inserted in 55 patients in sites with total loss of the buccal bone wall between 2008 and 2021. The implants were inserted and the buccal gaps were grafted by AB. A subgroup of 34 sites was grafted additionally with CTG using tunnel technique. Primary outcome was the vertical bone regeneration in height and thickness. Secondary outcome parameters were interproximal marginal bone level, recession, soft tissue esthetics (PES), width of keratinized mucosa (KMW) and probing depths (PPD).

RESULTS

Mean follow-up period was 60.8 months. In 55 sites a complete vertical bone regeneration was documented. The mean buccal bone level increased by 10.6 mm significantly. The thickness of the buccal bone wall ranged between 1.7 and 1.9 mm, and was significantly thicker in sites without CTG. Interproximal marginal bone level was at implant shoulder level. The mean recession improved significantly by 1.2 mm. In sites with CTG, recessions and PES improved significantly more.

CONCLUSIONS

Additional CTG in extraction sites with total buccal bone loss followed by IIP with simultaneous AB grafting led to improved PES and recession, but also to a thinner buccal bone wall compared to sites grafted just with AB.

Autogenous graft versus collagen matrices for peri-implant soft tissue augmentation. A systematic review and network meta-analysis

OBJECTIVE

The primary objective of this review is to compare autogenous soft tissue grafts (connective tissue graft - CTG and free gingival graft-FGG) with different type of matrices (acellular dermal matrix-ADM, xenograft collagen matrix-XCM, volume-stable collagen matrix-VCMX) used to increase peri-implant soft tissues.

MATERIALS AND METHODS

A search on electronic databases was performed to identify randomized and non-randomized controlled trials (RCTs and CCTs, respectively) with either parallel or split-mouth design, and treating ≥ 10 patients. A network meta-analysis (NMA) was used to compare different matrices. Soft tissue thickness dimensional changes and keratinized width (KMW) changes were the primary outcome measures. The secondary outcomes were to evaluate: a) PROMs; b) volumetric changes; c) surgical operating time; and d) different periodontal measurements.

RESULTS

A total of 23 studies were included in the qualitative analysis, and 16 studies (11 RCTs and 5 CCTs) in the quantitative analysis. A total of N = 573 sites were evaluated for NMA. CTG resulted the best material for increasing peri-implant soft tissue thickness, at 180 and 360 days after surgery. The use of an ADM showed good results for buccal thickness increase, primarily in the first three months after surgery. Vestibuloplasty + FGG resulted in the most effective technique for peri-implant KMW augmentation, after 180 days.

CONCLUSIONS

While CTG demonstrated better performance in all the comparison and FGG showed to be the best graft to increase keratinized mucosa up to 90 days, ADM and VCMX may be used to increase soft tissue horizontal thickness with lower patients' morbidity.

LIMITATIONS

The limits of this NMA are the following: a) limited number of included studies; b) high heterogeneity among them (number of patients, treatment sites, surgical techniques, outcome measures, and follow-ups).

CLINICAL RELEVANCE

Many studies compared the efficacy of autogenous and non-autogenous grafts in terms of gingival thickness, volume, and keratinized width increase. However, there is still not clear overall evidence on this topic. This NMA helps clinicians to choose the right material in different peri-implant soft tissue procedures. Recommendations for future studies are mandatory.

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.

Xenogeneic collagen matrix versus connective tissue graft for soft tissue augmentation at immediately placed implants: a prospective clinical trial

The advantages of immediate implant placement for patients include a reduced number of surgical procedures and a shorter overall treatment time. Disadvantages include a higher risk of aesthetic complications. The aim of this study was to compare xenogeneic collagen matrix (XCM) versus a subepithelial connective tissue graft (SCTG) used for soft tissue augmentation in combination with immediate implant placement without provisionalization. Forty-eight patients requiring a single implant-supported rehabilitation were selected and assigned to one of two surgical procedures: immediate implant with SCTG (SCTG group) or immediate implant with XCM (XCM group). Marginal changes in the peri-implant soft tissue and the facial soft tissue thickness (FSTT) were assessed after 12 months. Secondary outcomes included peri-implant health status, aesthetics, patient satisfaction, and perceived pain. All of the implants placed were successfully osseointegrated, resulting in 1-year survival and success rates of 100%. The patients in the SCTG group had a significantly lower mid-buccal marginal level (MBML) recession (P = 0.021) and a greater increase in FSTT (P < 0.001) than the patients in the XCM group. Using xenogeneic collagen matrix during immediate implant placement significantly increased FSTT from the baseline, leading to good aesthetic and patient satisfaction results. However, the connective tissue graft yielded better MBML and FSTT results.

Injectable Platelet-Rich Fibrin and Microneedling—A Non-Surgical Approach for Gingival Augmentation: A Randomized Controlled Clinical Trial

Aim:

The present study aimed to assess the efficacy of combining microneedling (MN) and injectable platelet-rich fibrin (i-PRF) administration with i-PRF alone in augmenting the thickness of gingiva to manage thin periodontal phenotype.

Methodology:

The clinical trial involved 36 patients who were diagnosed with thin periodontal phenotype. They were randomized under two groups: MN + i-PRF versus i-PRF alone, carried out as a split-mouth trial. One quadrant was treated only with i-PRF delivery through the gingival sulcus, while the contralateral side was treated with MN and i-PRF in 3 sessions at 10-day intervals. The primary parameter measured was the thickness of the gingiva, at baseline and 3 months following therapy. Statistical analysis was performed using the Mann-Whitney U test. Wilcoxon’s signed ranking test for inter-group and intra-group analysis, respectively.

Results:

The study results showed a significantly greater increase in gingival thickness (GT) in sites where both MN and i-PRF injection was done, compared to i-PRF alone, with a p value of .04.

Conclusion:

Both treatment modalities showed improvement in GT, being a minimally invasive alternative for mucogingival surgery. Adjunctive MN was found to be more beneficial than i-PRF alone. However, further research should be carried out to address the drawbacks of the study and for a better understanding of this novel approach.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSION

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

CLINICAL RELEVANCE

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

Minimal invasiveness in soft tissue augmentation at dental implants: A systematic review and meta-analysis of patient-reported outcome measures

The aim of this study was to compare patient-reported outcome measures (PROMs) of soft tissue substitutes versus autogenous grafts for soft tissue augmentation procedures at implant sites. Comprehensive and systematic literature searches were performed until December 2021. A focused question was formulated based on the Population, Intervention, Comparison and Outcome criteria (PICO): In patients with dental implants undergoing soft tissue augmentation (P), do soft tissue substitutes (I) compared to autogenous soft tissue graft (SCTG [subepithelial connective tissue graft]) (C) limit the post-operative morbidity and other patient reported-outcomes measures (O). Randomized controlled clinical trials, prospective-, retrospective- and case-series studies were included. Meta-analyses were performed whenever possible and the results were expressed as weighted mean differences (WMD). A total of 29 clinical studies were included. For mucosal thickness gain, soft tissue substitutes significantly reduced the pain perception compared to SCTG (n = 4; WMD = 14.91 Visual Analog Scale [VAS] units; 95% confidence interval [CI] 6.42-23.40; P < .0006) based on a 0-100 VAS scale. Based on a 0-10 VAS scale, a borderline significance of pain reduction was found when soft tissue substitutes were applied (n = 4; WMD = 1.62 VAS units; 95% CI 0.01-3.23; P = .05). For keratinized tissue gain, soft tissue substitutes significantly reduced the pain perception after keratinized tissue augmentation compared to SCTG based on a 0-100 VAS scale (n = 2; WMD = 21.43 VAS units; 95% CI 12.58-30.28; P < .0001). Based on the 0-10 VAS scale, soft tissue substitutes significantly reduced the pain as compared to SCTG (n = 4; WMD = 1.65 VAS units; 95% CI 0.66-2.64; P = .001). Regarding pain medication, soft tissue substitutes required less painkillers (n = 6; WMD = 1.56 tablets; 95% CI 1.22-1.91; P < .00001) after soft tissue augmentation. The surgery time was significantly reduced when soft tissue substitutes were used (n = 5; WMD = 10.9 minutes; 95% CI 4.60-17.19; P < .00001). There were no significant differences in satisfaction, aesthetics, and quality of life (OHIP-14) between soft tissue substitutes and autogenous grafts following soft tissue augmentation at implants sites. Soft tissue substitutes, compared to autogenous grafts, significantly improve PROMs following soft tissue augmentation at implant sites. Soft tissue substitutes can reduce pain perception, amounts of painkillers and surgery time while achieving similar levels of patient´s satisfaction as autogenous grafts without impairing the clinical outcomes. The current evidence indicates that they constitute a valid and reliable alternative to minimize the invasiveness in soft tissue augmentation procedures at implant sites.

Novel biohybrid spongy scaffolds for fabrication of suturable intraoral graft substitutes

Despite the fact that classic autograft is the gold standard material for periodontal plastic surgery, it has some drawbacks, including the need for a second surgical site and the scarcity of palatal donor tissue. However, only a few research works on the manufacturing of bioengineered intraoral connective tissue grafts have been conducted. In this work, porous bovine serum albumin methacryloyl/gelatin methacryloyl (BG) biohybrid scaffolds were developed for super-elasticity, shape recovery, suturability for persistent stability, sufficient scaffolding function, and convenient manipulating characteristics to fabricate an intraoral graft substitute with superb stability to resist frequent dynamic forces caused by functional movement (speaking, masticating, and swallowing). Furthermore, in a 3D cell culture assay, BG scaffolds demonstrated excellent cell adhesion and proliferation of L929 cells. In addition, the BG scaffolds were able to release Ibuprofen in a controlled manner for postoperative recovery. The use of a low-cost, optimized cryogelation technique for functional biomacromolecules offers up new possibilities to develop promising scaffolds for dental clinical settings.

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.

Histologic composition of marginal mucosal tissue augmented by a resorbable volume-stable collagen matrix in soft tissue thickening procedures in humans: a morphometric observational study

AIM

This study aims to examine the composition of lining and masticatory mucosa at the pre- and post-soft tissue augmentation procedures with a volume-stable cross-linking collagen matrix (VCMX) in humans.

MATERIALS AND METHODS

In 12 patients, single implant sites were augmented with a VCMX. Biopsies were obtained including masticatory (MM) and lining (LM) mucosa before augmentation and at 12 weeks post-augmentation procedures. Rete pegs density (RPD), length (RPL), and blood vessel density (BVD) were histomorphometrically analyzed at both time points. Picrosirius red staining under polarized light microscopy was used to evaluate collagen fiber organization. The effects of time and tissue type were evaluated by ANOVA with repeated measures.

RESULTS

Both MM and LM areas demonstrated an increase in mean RPL following augmentation, 382.6 µm ± 95.1 vs. 290.5 µm ± 79.3 and 335.6 µm ± 94.2 vs. 292.9 µm ± 77.0, respectively (p < .05). There was a significant difference in the numbers of RP per 1 mm length (RPD) between the MM (9.2 ± 1.7) and LM (6.1 ± 2.8) mucosa but not between the pre- and post-VCMX augmentation time points. The mean BVD in the LM was greater than in the MM (5.5 ± 2.4 and 6.3 ± 2.4 vs. 3.4 ± 3.3 and 3.7 ± 1.8, respectively, p < .05) but not between time points. The collagen fiber arrangements pre- and post-augmentation were not significantly different.

CONCLUSION

Augmentation with VCMX did not alter the composition of lining and masticatory mucosa at implant sites.

CLINICAL RELEVANCE

A thick soft tissue phenotype around the implant neck is an important factor to maintain peri-implant health. A non-autogenous cross-linking collagen matrix is proposed as an alternate graft substitute in soft tissue augmentation procedures in order to improve implant soft tissue phenotype.