Healing of a xenogeneic collagen matrix for keratinized tissue augmentation

Posterior open wound healing in immediate implant placement using reactive soft tissue versus absorbable collagen sponge: a retrospective cohort study

The soft and hard tissue healing of open wounds in immediate implant placement are yet to be explored. The aim of this study was to compare the clinical outcomes of open wound healing using reactive soft tissue (RST) and absorbable collagen sponge (ACS). Forty implants placed immediately in posterior sockets were included; autologous RST was used in 20 and ACS substitute was used in 20. Soft tissue healing was primarily assessed through a novel scoring system and the evaluation of gingival recession. The horizontal bone width (HBW) and interproximal marginal bone level (MBL) were measured on radiographs to observe the hard tissue healing. No significant difference in total soft tissue healing score was observed at 2 weeks postoperatively. Notably, the ACS group showed better tissue colour (P = 0.016) but worse fibrous repair (P = 0.043) scores than the RST group. Gingival recession levels were comparable in the two groups, both before tooth extraction and after placement of the restoration. Regarding hard tissue, HBW and MBL changes showed no intergroup differences. Within the limitations of this study, both RST and ACS seemed effective for open wound closure, achieving ideal soft and hard tissue healing in immediate implant placement.

Effect of polydeoxyribonucleotide with xenogeneic collagen matrix on gingival phenotype modification: a pilot preclinical study

PURPOSE

To investigate the effect of xenogeneic collagen matrix (XCM) with polydeoxyribonucleotide (PDRN) for gingival phenotype modification compared to autogenous connective tissue graft.

METHODS

Five mongrel dogs were used in this study. Box-type gingival defects were surgically created bilaterally on the maxillary canines 8 weeks before gingival augmentation. A coronally positioned flap was performed with either a subepithelial connective tissue graft (SCTG) or XCM with PDRN (2.0 mg/mL). The animals were sacrificed after 12 weeks. Intraoral scanning was performed for soft tissue analysis, and histologic and histomorphometric analyses were performed.

RESULTS

One animal exhibited wound dehiscence, leaving 4 for analysis. Superimposition of STL files revealed no significant difference in the amount of gingival thickness increase (ranging from 0.69±0.25 mm to 0.80±0.31 mm in group SCTG and from 0.48±0.25 mm to 0.85±0.44 mm in group PDRN; P>0.05). Histomorphometric analysis showed no significant differences between the groups in supracrestal gingival tissue height, keratinized tissue height, tissue thickness, and rete peg density (P>0.05).

CONCLUSIONS

XCM soaked with PDRN yielded comparable gingival augmentation to SCTG.

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.

[Kinetics of mucosal blood flow in 3D modeling of the gingival contour around dental implants after bone reconstruction of the alveolar ridge in the lateral part of the jaws]

OBJECTIVE

To study the kinetics of mucosal blood flow in 3D modeling of the gingival contour around dental implants after bone reconstruction of the alveolar ridge in the posterior jaw.

MATERIAL AND METHODS

The work was performed at the clinical base of the Department of Surgical Dentistry and Maxillofacial Surgery of the Institute of Dentistry of the Privolzhsky Research Medical University, Nizhny Novgorod, Russia with the participation of 87 patients who were divided into two groups depending on the chosen method of treatment and a control group. The method of laser Doppler flowmetry was carried out using a multifunctional laser diagnostic complex LAKK-02. The terms of observation were 7, 14, 28, 42 days.

RESULTS

On the 7th postoperative day, the decrease in microcirculation index (MI) in the groups reflected moderately pronounced hemodynamic disorders with a predominance of a decrease in MI in the center (by 35.8%). The predominance of the stagnant-ischemic type of microcirculation disorders and low intensity of neoangiogenesis was established, especially in the central zone in group 1, and in group 2 signs of neoangiogenesis were noted by the 7th day. By the 14th day, there was a decrease in venous congestion and signs of arterial inflow. In the 2nd group there was a subsidence of inflammatory phenomena and an increase in the energy of the oscillatory process in the vessels. Gradually, by the 42nd day, the indicators in groups 1 and 2 approached in value to the control group and did not differ significantly.

CONCLUSION

A previously unknown mechanism of interaction between two heterogeneous grafts (xenograft and thin free gingival graft) was revealed, which determined neoangiogenesis by the traditional method (from the center to the periphery), and by the proposed method (from the periphery to the center). Understanding the wound process is necessary for the purpose of further correction of the surgical technique for the best restoration of the vascular network and an increase in the success rate of operations.

Porcine Acellular Dermal Matrix: An Alternative to Connective Tissue Graft-A Narrative Review

Porcine acellular dermal matrix has recently been introduced in dentistry as an alternative to the gold standard connective tissue graft especially for the use in gingival recession treatments and soft tissue augmentation in implant surgery. Connective tissue grafts are inconvenient and require a second surgical site leading to greater morbidity, longer surgical procedures, and a more painful postoperative phase for the patient. Other options such as allografts have ethical concerns and are less available in Europe. Thus, dental professionals have sought other techniques and materials. Porcine acellular dermal matrix results in periodontal recession treatment with a gain in recession coverage as well as increased keratinized tissue and soft tissue augmentation. This leads to more keratinized mucosa and greater tissue thickness. Many studies have been published using collagen matrices, but a few strictly use porcine acellular dermal matrix, which have been studied in prospective randomized clinical trials with a large number of patients and longer follow-up periods (more than 5 years). Nevertheless, more data are needed to confirm that the porcine acellular dermal matrix is a suitable alternative although its favourable results to date suggest a positive future.

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.

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 substitutes to increase gingival thickness: Histologic and volumetric analyses in dogs

OBJECTIVES

To evaluate the histologic and volumetric changes of gingival tissues following grafting with collagen-based matrices at labial aspect of teeth in canines.

MATERIALS AND METHODS

Gingival augmentation was performed in the mandibular incisor area using two types of xenogeneic cross-linked collagen matrices (CCMs), bovine CCM for BCCM group and porcine CCM for PCCM group, whereas the contralateral sides remained untreated (B-control group and P-control group). Descriptive histology, histometric and volumetric analyses were performed after 12 weeks. For statistical comparison between each test group and respective control group, paired t test was used for histometric analysis, and repeated-measured analysis of variance was used for volumetric analysis (p < 0.05).

RESULTS

An increased number of rete pegs and an enhanced formation of new blood vessels were observed at both grafted sites compared to the corresponding control sites. There was statistically significant gain of horizontal thickness only in BCCM group (1.36 ± 0.27 mm vs. 1.26 ± 0.34 mm; p < 0.05) compared to the B-control groups.

CONCLUSION

BCCM was effective for gingival augmentation in terms of horizontal thickness at the labial aspect of teeth at 12 weeks post-surgery.

The Use of a Novel Porcine Derived Acellular Dermal Matrix (Mucoderm) in Peri-Implant Soft Tissue Augmentation: Preliminary Results of a Prospective Pilot Cohort Study

Objective

Over the years, several techniques have been proposed for soft tissue augmentation around dental implants in order to improve keratinized mucosa width (KMW). Recently, a porcine derived acellular dermal matrix (Mucoderm®) has been proposed as autogenous graft substitute in order to avoid palatal harvesting and obtain comparable results to connective tissue grafts, in terms of aesthetics and function. The aim of this study is to present the one-year follow-up results of this matrix in peri-implant soft tissue augmentation procedures.

Material and Methods

Twelve patients were enrolled in this pilot prospective study: a dental implant was placed in the upper premolar area and, at implant uncovering after eight weeks, the matrix was inserted. KMW gain was considered as primary outcome variable.

Results

After one month from matrix insertion, mean KMW was 7.86±3.22 mm (100%), with no statistically significant intragroup variations (p>0.05). No membrane exposures or wound healing complications occurred during postoperative phase and, after one year, mean KMW was 5.67±2.12 mm (72.13%).

Conclusions

The results of the present pilot study indicate that by placing a Mucoderm membrane during implant surgery the keratinized tissue width can be augmented, and the width remains stable for the assessment period of 12 months. Further studies with greater power and longer investigation period are needed to confirm the suggestion for clinical use. Clinical trial registration number is EudraCT number 2018-000147-16.

The efficacy of a porcine collagen matrix in keratinized tissue augmentation: a 5-year follow-up study

Background

When keratinized tissue width around dental implants is poorly represented, the clinician could resort to autogenous soft tissue grafting. Autogenous soft tissue grafting procedures are usually associated with a certain degree of morbidity. Collagen matrices could be used as an alternative to reduce morbidity and intra-operatory times. The aim of this study was to assess the efficacy of a xenogeneic collagen matrix as a substitute for soft tissue grafting around dental implants.

Methods

Fifteen consecutive patients underwent a vestibuloplasty and keratinized tissue reconstruction around dental implants, both in the mandible and the maxilla, with a porcine collagen matrix. The so obtained keratinized tissues were measured and evaluated after 6 months and 1, 4, and 5 years.

Results

The average gain of keratinized tissue was 5.7 mm. After 6 months, it was observed a resorption of 37%, after 1 year 48%, and after 5 years 59%. The mean gain of keratinized tissue after 5 years was 2.4 mm. Hemostatic effect and post-operative pain were evaluated too. All subjects referred minimal pain with no bleeding. No adverse reaction nor infection was noted.

Conclusions

The present study showed the efficacy of a porcine collagen matrix in keratinized tissue augmentation. The possibility to use a soft tissue substitute is a great achievement as morbidity decreases and bigger areas can be treated in a single surgery.

Ridge preservation using an in situ hardening biphasic calcium phosphate (β-TCP/HA) bone graft substitute-a clinical, radiological, and histological study

BACKGROUND

Post-Extraction ridge preservation using bone graft substitutes is a conservative technique to maintain the width of the alveolar ridge. The objective of the present study was to evaluate an in situ hardening biphasic (HA/β-TCP) bone graft substitutes for ridge preservation without primary wound closure or a dental membrane.

METHODS

A total of 15 patients reported for tooth extraction were enrolled in this study. Implants were placed in average 5.2 ± 2 months after socket grafting. At this visit, Cone Beam CT (CBCT) images and core biopsies were taken. Implant stability (ISQ) was assessed at the insertion as well as at the day of final restoration.

RESULTS

CBCT data revealed 0.79 ± 0.73 mm ridge width reduction from grafting to implant placement. Histomorphometric analysis of core biopsy samples revealed in average 21.34 ± 9.14% of new bone in the grafted sites. Primary implant stability was high (ISQ levels 70.3 ± 9.6) and further increased until final restoration.

CONCLUSIONS

The results of this study show that grafting of intact post-extraction sockets using a biphasic in situ hardening bone graft substitute results in an effective preservation of the ridge contour and sufficient new bone formation in the grafted sites, which is imperative for successful implant placement.

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

OBJECTIVES

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

MATERIALS AND METHODS

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

RESULTS

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

CONCLUSIONS

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

CLINICAL RELEVANCE

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

Palatal wound healing using a xenogeneic collagen matrix - histological outcomes of a randomized controlled clinical trial

AIM

The aim of this study was to test whether or not a collagen matrix can improve early wound healing compared to spontaneous healing based on histological and immunohistologic analyses.

METHODS

In 20 volunteers, 6 mm punch biopsies were harvested at the palate. A xenogeneic collagen matrix (XCM) was sutured in one site; the other one was left untreated (control). Biopsies with a diameter of 8 mm were subsequently obtained at 4, 8, 15 and 29 days and histological and immunohistologic analyses were performed.

RESULTS

At day 4, wound bed keratinization amounted to 12.4 ± 7.5% (control) and 18.0 ± 10.2% (XCM). This increased up to day 8 (19.7 ± 25.5% control; 29.1 ± 8.0% XCM) and reached complete keratinization at day 15 in both groups. The quantitative analyses of the superficial compartment measured an increase in the amount of granulation tissue (32-88% control; 14-41% XCM) from day 4 to day 8. Angiogenesis was first detected at 8 days. At day 29, the amount of connective tissue in all compartments reached values similar to the native tissue at baseline.

CONCLUSIONS

The application of a XCM as a wound dressing on palatal wounds might be beneficial in the early stages of wound healing. Further research with a larger sample size is needed to confirm these results.

Advances in collagen, chitosan and silica biomaterials for oral tissue regeneration: from basics to clinical trials

Different materials have distinct surface and bulk characteristics; each of them potentially useful for the treatment of a particular wound or disease.

Long-term outcomes after vestibuloplasty with a porcine collagen matrix (Mucograft® ) versus the free gingival graft: a comparative prospective clinical trial

OBJECTIVES

Porcine collagen matrices are proclaimed being a sufficient alternative to autologous free gingival grafts (FGG) in terms of augmenting the keratinized mucosa. The collagen matrix Mucograft^® (CM) already showed a comparable clinical performance in the early healing phase, similar histological appearance, and even a more natural appearance of augmented regions. Predictability for long-term stability does not yet exist due to missing studies reporting of a follow-up >6 months.

MATERIAL AND METHODS

The study included 48 patients with atrophic edentulous or partially edentulous lower jaw situations that had undergone an implant treatment. In the context of implant exposure, a vestibuloplasty was either performed with two FGGs from the palate (n = 21 patients) or with the CM (n = 27 patients). Surgery time was recorded from the first incision to the last suture. Follow-up examinations were performed at the following time points: 10, 30, 90, and 180 days and 1, 2, 3, 4, and 5 years after surgery. The width of keratinized mucosa was measured at the buccal aspect of each implant, and augmented sites were evaluated in terms of their clinical appearances (texture and color).

RESULTS

The groups showed similar healing with increased peri-implant keratinized mucosa after surgery (FGG: 13.06 mm ± 2.26 mm and CM: 12.96 mm ± 2.86 mm). The maximum follow-up was 5 years (5 patients per group). After 180 days, the width of keratinized mucosa had decreased to 67.08 ± 13.85% in the FGG group and 58.88 ± 14.62% in the CM group with no statistically significant difference. The total loss of the width of keratinized mucosa after 5 years was significant between the FGG (40.65%) and the CM group (52.89%). The CM group had significantly shorter operation times than the FGG group. Augmented soft tissues had a comparable clinical appearance to adjacent native gingiva in the CM group. FGGs could still be defined after 5 years.

CONCLUSIONS

The FGG and the CM are both suitable for the regeneration of the peri-implant keratinized mucosa with a sufficient long-term stability. With the CM, tissue harvesting procedures are invalid, surgery time can be reduced, and regenerated tissues have a more esthetic appearance.