Dimensional changes in soft tissues around dental implants following free gingival grafting: an experimental study in dogs

High-Density Dermal Matrix for Soft Tissue Augmentation Using a Matrix Tissue Graft Technique-A Comprehensive Multicenter Analysis of 20 Implants: A 1-Year Follow-Up Retrospective Study

Background: In this multicenter case series analysis, the authors present successful instances of 20 single-screw-retained and implant-supported prosthetic rehabilitation samples. Methods: A high-density heterologous dermal matrix (Derma® Osteobiol by Tecnoss, Torino, Italy) was employed with a specific technique named the matrix tissue graft (MTG) in all these cases characterized by an inadequate initial supra-crestal tissue height (thin if 1 mm or medium if 2 mm) to enhance the peri-implant soft tissues both vertically and horizontally. Results: The implants were deemed successful in all cases, yielding a success proportion of 100% (one-sided 97.5% confidence interval = 83.2-100%). The buccal and lingual gains were, respectively, 2.2 ± 0.38 mm (range 1.7-3.22 mm) and 0.83 ± 0.33 mm (range 0.1-1.5 mm). These measurements were calculated as the maximum distance between two superimposed .stl file models (derived from two different IOS devices) scanned before implant placement and 1 year after dermal matrix healing. Conclusions: An outstanding vertical and horizontal gain was obtained using this heterologous derma matrix placed above the bone crest and surrounding the dental implants.

Regeneration of keratinized tissue around teeth and implants following coronal repositioning of alveolar mucosa with and without a connective tissue graft: An experimental study in dogs: Fifty years after Karring's landmark study: Fifty years after Karring's 71 landmark study

AIM

To compare clinical and histological keratinized tissue formation around teeth and implants following coronal repositioning of alveolar mucosa with or without a connective tissue graft (CTG).

MATERIALS AND METHODS

In nine beagle dogs, the third and fourth premolars (P3 and P4) were extracted from one side of the maxilla. Three months after the tooth extraction, a full-thickness buccal flap was raised and two implants were placed in those healed areas. On the contra-lateral side, a buccal flap was also raised at the P3 and P4 areas. Before suturing, the dogs were randomly assigned to three study groups (control, non-keratinized tissue [NKT], and non-keratinized tissue CTG [NKT-CTG]). In the control group, the buccal flaps were re-positioned around the teeth (P3 and P4) on one side, and implants on the other side, presenting an adequate band of keratinized tissue (KT). For the NKT and NKT-CTG groups, this buccal KT was then excised. In the NKT group, the buccal flap without KT (alveolar mucosa) was re-positioned around the teeth and implants. In the NKT-CTG group, a CTG taken from the excised KT was sutured to the buccal alveolar mucosa and then both were re-positioned around the teeth and implants. The clinical height of the KT was measured at baseline and at 1, 2, and 3 months of healing. The animals were sacrificed at 3 months, at which point the KT height was measured histologically.

RESULTS

The control group presented normal healing with a band of KT surrounding the teeth and implants. In the NKT and NKT-CTG groups, a new KT band approximately 2 mm in height (measured clinically and histologically) spontaneously formed around all teeth, regardless of whether a CTG had been placed. In the NKT implant group, no new KT was observed (clinically or histologically). Around the implants in the NKT-CTG group, a small amount of KT was formed in just two of the six implants.

CONCLUSIONS

After surgical excision of KT, spontaneous KT is formed around teeth but not around implants, regardless of the placement of a CTG.

Effect of free gingival graft before implant placement on peri-implant health and soft tissue changes: a randomized controlled trial

BACKGROUND

To evaluate the clinical outcome and changes in posterior buccal soft tissue following implant restoration in groups with and without a free gingival graft (FGG) before implant placement.

METHODS

Twenty-six individuals who required implant restoration and displayed lack of keratinized mucosa (KM) were recruited and assigned to the FGG group (with FGG before implant placement) or Control group (without FGG before implant placement) randomly. A screw-retained conventional implant restoration was performed for each patient. Peri-implant soft tissue was captured by an intraoral scanner and analyzed by an image processing software. Clinical parameters (plaque index, gingival index, probing depth, and bleeding on probing) were assessed at baseline and 1, 3, 6, and 12 months. Buccal soft tissue changes (mucosal margin, soft tissue thickness, and width of keratinized mucosa) on the buccal side of implant site were assessed at 1, 3, 6, and 12 months. Two-way ANOVA and Bonferroni test were used to analyze significant difference between groups at each time point (α = 0.05).

RESULTS

The clinical parameters were lower in the FGG group than that in the Control group, although there were no significant differences between the two groups (P > 0.05). Peri-implant soft tissue collapsed and the changes (mucosal margin and soft tissue thickness) were significantly greater in the Control group than the FGG group (P < 0.05). Width of KM was larger in the FGG group than the Control group, although there was no significant difference between the two groups (P > 0.05).

CONCLUSIONS

Minimal peri-implant soft tissue changes occurred in two groups. Performing FGG before implant placement is a viable procedure to maintain peri-implant soft tissue but might not affect peri-implant health during 12 months follow-up. However, small sample size must be considered. Trial registration This study was retrospectively registered in the Chinese Clinical Trial Registry (Registration number: ChiCTR2000037954; Date of registration: 6 September 2020).

Efficacy of free gingival graft in the augmentation of keratinized tissue around implants: A prospective clinical study

Background

Effectuating adequate width of keratinized tissue (WKT) can lead to a healthy and stable implant/soft tissue interface which is important for the long term success of the implant. The use of free gingival grafts (FGG) for widening the WKT around dental implants increases the amount of attached gingival tissue and prevents clinical attachment loss.

Aim

The aim of the study was to assess the ability of FGG to create a healthy implant/soft tissue interface.

Methods and Material

A total of 10 edentulous sites in 10 patients with inadequate keratinized tissue indicated for replacement of missing teeth were treated. An implant was placed in edentulous sites and the keratinized tissue was augmented using FGG at the second stage of implant surgery. WKT was recorded at baseline, 3rd month and 6th month post-operatively. Plaque index (PI), gingival index (GI), probing depth (PD) and papillary index (PPI) and were recorded at 3 and 6 months post-operatively to evaluate the health of peri-implant tissues. Paired t-test was used for standard deviation and the level of significance was taken as 5% (P < 0.05).

Results

The WKT at 3 (3.2±1.61mm) and 6 months (3±1.56 mm) compared to the baseline was statistically significant (P = 0.034). The other parameters PI, GI, PD, PPI showed no clinical significance from 3 and 6 months (P > 0.05).

Conclusions

Augmentation of FGG created a significant gain in the WKT which resulted in a healthy implant/soft tissue interface.

Keratinized tissue gain after free gingival graft augmentation procedures around teeth and dental implants: A prospective observational study

AIM

The primary goal was to compare the amount of keratinized tissue width (KTW) gain after free gingival graft (FGG) procedures around implants and teeth after 6 and 12 months of healing.

MATERIALS AND METHODS

Patients with mucogingival defects (<2 mm of KT) around teeth and implants underwent a gingival augmentation procedure by means of a FGG. Clinical measurements were performed with an individual stent to determine keratinized tissue width (KTW), length (KTL), graft shrinkage (GS) and gingival margin position (GMP) at 2 weeks, 6 weeks, 3 months, 6 months and 12 months after surgery.

RESULTS

Twenty-nine patients (35 sites) participated in this prospective study. After surgery, KTW decreased and GS increased significantly in both treatment groups during the whole follow-up period, but the biggest changes were observed at 6 weeks. When comparing both treatment groups, implant sites showed significantly more reduction in KTW and more GS. Thus, at 12 months, KTW and GS reduced 2.03 ± 2.1 mm and 36.74 ± 38.2% in the teeth group and 2.91 ± 12.03 mm and 61.8 ± 36.25% around implants, respectively.

CONCLUSIONS

A significantly greater reduction in KTW and more GS might be expected at implant sites.

Prospective study assessing three-dimensional changes of mucosal healing following soft tissue augmentation using free gingival grafts

BACKGROUND

The present study aimed to assess the three-dimensional changes following soft tissue augmentation using free gingival grafts (FGG) at implant sites over a 3-month follow-up period.

METHODS

This study included 12 patients exhibiting deficient keratinized tissue (KT) width (i.e., <2 mm) at the vestibular aspect of 19 implants who underwent soft tissue augmentation using FGG at second stage surgery following implant placement. Twelve implants were considered for the statistical analysis (n = 12). The region of interest (ROI) was intraorally scanned before surgery (S0), immediately post-surgery (S1), 30 (S2) and 90 (S3) days after augmentation. Digital scanned files were used for quantification of FGG surface area (SA) and converted to standard tessellation language (STL) format for superimposition and evaluation of thickness changes between the corresponding time points. FGG shrinkage (%) in terms of SA and thickness was calculated between the assessed time points.

RESULTS

Mean FGG SA amounted to 91 (95% CI: 63 to 119), 76.2 (95% CI: 45 to 106), and 61.3 (95% CI: 41 to 81) mm² at S1, S2, and S3, respectively. Mean FGG SA shrinkage rate was 16.3% (95% CI: 3 to 29) from S1 to S2 and 33% (95% CI: 19 to 46) from S1 to S3. Mean thickness gain from baseline (S0) to S1, S2, and S3 was 1.31 (95% CI: 1.2 to 1.4), 0.82 (95% CI: 0.5 to 1.12), and 0.37 (0.21 to 0.5) mm, respectively. FGG thickness shrinkage was of 38% (95% CI: 17.6 to 58) from S1 to S2 and 71.8% (95% CI: 60 to 84) from S1 to S3. Dimensional changes from S1 to S3 were statistically significant, P <0.017. Soft tissue healing was uneventful in all patients.

CONCLUSIONS

The present three-dimensional assessment suggests that FGG undergo significant dimensional changes in SA and thickness over a 3-month healing period.

Influence of implant mucosal thickness on early bone loss: a systematic review with meta-analysis

Purpose

Marginal bone loss (MBL) is an important clinical issue in implant therapy. One feature that has been cited as a contributing factor to this bone loss is peri-implant mucosal thickness. Therefore, in this report, we conducted a systematic review of the literature comparing bone remodeling around implants placed in areas with thick (≥2-mm) vs. thin (<2-mm) mucosa.

Methods

A PICO question was defined. Manual and electronic searches were performed of the MEDLINE/PubMed and Cochrane Oral Health Group databases. The inclusion criteria were prospective studies that documented soft tissue thickness with direct intraoperative measurements and that included at least 1 year of follow-up. When possible, a meta-analysis was performed for both the overall and subgroup analyses.

Results

Thirteen papers fulfilled the inclusion criteria. A meta-analysis of 7 randomized clinical trials was conducted. Significantly less bone loss was found around implants with thick mucosa than around those with thin mucosa (difference, −0.53 mm; P<0.0001). Subgroups were analyzed regarding the apico-coronal positioning, the use of platform-matched vs. platform-switched (PS) connections, and the use of cement-retained vs. screw-retained prostheses. In these analyses, thick mucosa was found to be associated with significantly less MBL than thin mucosa (P<0.0001). Among non-matching (PS) connections and screw-retained prostheses, bone levels were not affected by mucosal thickness.

Conclusions

Soft tissue thickness was found to be correlated with MBL except in cases of PS connections used on implants with thin tissues and screw-retained prostheses. Mucosal thickness did not affect implant survival or the occurrence of biological or aesthetic complications.

Trial Registration

International Prospective Register of Systematic Reviews (PROSPERO): CRD42018084598

Effect of Rough Surface Platforms on the Mucosal Attachment and the Marginal Bone Loss of Implants: A Dog Study

The preservation of peri-implant tissues is an important factor for implant success. This study aimed to assess the influence of the surface features of a butt-joint platform on soft-tissue attachment and bone resorption after immediate or delayed implant placement. All premolars and first molars of eight Beagle dogs were extracted on one mandible side. Twelve-weeks later, the same surgery was developed on the other side. Five implants with different platform surface configurations were randomly inserted into the post-extracted-sockets. On the healed side, the same five different implants were randomly placed. Implants were inserted 1 mm subcrestal to the buccal bony plate and were connected to abutments. The primary outcome variables were the supracrestal soft tissue (SST) adaptation and the bone resorption related to the implant shoulder. The SST height was significantly larger in immediate implants (IC95% 3.9–4.9 mm) compared to delayed implants (IC95% 3.1–3.5 mm). Marginal bone loss tended to be higher in immediate implants (IC95% 0.4–0.9 mm) than in delayed implants (IC95% 0.3–0.8 mm). Linear-regression analysis suggested that the SST height was significantly affected by the configuration of the platform (0.3–1.9 mm). Roughened surface platforms resulted in higher SST height when compared to machined surface platforms. Marginal bone loss was less pronounced in roughened designs.

Focus on Epithelialized Palatal Grafts. Part 2: Implant Site Development

INTRODUCTION

The epithelialized palatal graft (EPG), introduced in 1963, has persisted as the gold standard for gingival augmentation, and in the present era, mucosal augmentation around dental implants has become an important concern. A limited body of evidence suggests peri-implant mucosal augmentation may favorably impact bone and mucosal stability and peri-implant health under some circumstances. Although more contemporary procedures for peri-implant mucosal augmentation are often preferred based on convenience and esthetic considerations, EPG augmentation at dental implant sites is distinguishable from methods which do not deepen the vestibule and eliminate unfavorable superficial soft tissue. Implant sites augmented with EPG are qualitatively distinct from sites augmented using other methods.

CASE SERIES

Seven generally healthy patients received EPG augmentation before dental implant placement, at implant placement, before implant uncovering, or after implant uncovering. In each case, the patient exhibited a favorable zone of attached peri-implant mucosa following treatment.

CONCLUSIONS

Reliable mucosal augmentation with EPG is achievable at multiple phases in the course of dental implant therapy. EPG augmentation offers distinct clinical advantages and may be preferable to other mucosal augmentation strategies at some dental implant sites.

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.

Evaluation of Implant Collar Surfaces for Marginal Bone Loss: A Systematic Review and Meta-Analysis

Background. It is important to understand the influence of different collar designs on peri-implant marginal bone loss, especially in the critical area. Objectives. The purpose of the present systematic review and meta-analysis was to compare dental implants with different collar surfaces, evaluating marginal bone loss and survival rates of implants. Methods. Eligibility criteria included clinical human studies, randomized controlled trials, and prospective and retrospective studies, which evaluated dental implants with different collar surface in the same study. Results. Twelve articles were included, with a total of 492 machined, 319 rough-surfaced, and 352 rough-surfaced microthreaded neck implants. There was less marginal bone loss at implants with rough-surfaced and rough-surfaced microthreaded neck than at machined-neck implants (difference in means: 0.321, 95% CI: 0.149 to 0.493; p < 0.01). Conclusion. Rough and rough-surfaced microthreaded implants are considered a predictable treatment for preserving early marginal bone loss.

Palatal fibroblasts reduce osteoclastogenesis in murine bone marrow cultures

BACKGROUND

Preclinical studies support the assumption that connective tissue grafts preserve the alveolar bone from resorption; the underlying cellular mechanisms, however, remain unknown. The cellular mechanisms may be attributed to the paracrine activity of the palatal fibroblasts. It was thus reasonable to suggest that palatal connective tissue grafts reduce the formation of osteoclasts.

METHODS

To test this hypothesis, human palatal fibroblasts were examined for their capacity to modulate the formation of osteoclasts in murine bone marrow cultures exposed to RANKL, M-CSF and TGF-β1. Osteoclastogenesis was determined by tartrate-resistant acid phosphatase (TRAP) staining and gene expression analysis. The formation of antigen presenting cells was based on the expression of CD14 and costimmulatory molecules of antigen presenting cells. The paracrine interaction of fibroblasts and the bone marrow was modeled in vitro with inserts of cell-occlusive membranes.

RESULTS

In cocultures without cell-to-cell contact, palatal fibroblasts caused a decrease in the expression of the osteoclast marker genes in bone marrow cells; calcitonin receptors, cathepsin K, TRAP, and osteoclast-associated receptor. Also the number of TRAP positive multinucleated cells was decreased in the presence of fibroblasts. Notably, palatal fibroblasts increased the expression of CD14 and the co-stimulatory proteins CD40, CD80, and CD86 in bone marrow cells. Bone marrow cells had no considerable impact on fibroblast viability and proliferation marker genes. With regard to cell distribution, osteoclasts were most prominent in the center of the membranes, while fibroblasts accumulated immediately adjacent to the border of the insert forming a ring-like structure on the surface of the culture plate.

CONCLUSION

The data suggest that palatal fibroblasts provide a paracrine environment that reduces osteoclastogenesis and increases markers of antigen presenting cells. Morover, the paracrine model revealed a joint activity between palatal fibroblasts and bone marrow cells visualized by the characteristic cell distribution in the two separated compartments.

Concomitant Correction of a Soft-Tissue Fenestration with Keratinised Tissue Augmentation By Using A Rotated Double-Pedicle Flap During Second-Stage Implant Surgery- A Case Report

Soft tissue deficiencies and defects around dental implants have been observed frequently. Soft-tissue defects after implant procedures originate from the process of modelling of periimplant mucosa and often cause aesthetic disharmony, food debris accumulation and soft tissue shrinkage. Periimplant mucogingival surgery focuses on creating an optimum band of keratinized tissue resulting in soft tissue architecture similar to the gingiva around natural teeth. A 23-year-old male reported to the Department of Periodontology with a complaint of gum soreness, foul smell and food accumulation at a site where a 3.75 x 11.5mm implant was placed previously. On clinical examination, fenestration of tissue above the cover screw was observed and there appeared to be a keratinized tissue of 1mm surrounding the implant. The case was managed by use of a rotated double-pedicle flap during second-stage implant surgery to correct the soft-tissue fenestration defect and to obtain a keratinized periimplant soft tissue. A periosteal bed was prepared by giving a horizontal incision at the mucogingival junction to a depth of 4 mm. Two split-thickness keratinized pedicles were dissected from the mesial and distal interproximal tissues near the implant. After rotation, both the pedicles were sutured to each other mid-buccally and the pedicles were rigidly immobilized with sutures. At 1 month, there was a 3mm band of stable and firm keratinized tissue over the underlying tissues. The procedure resulted in an aesthetic improvement due to enhanced soft tissue architecture and optimum integration between the peri-implant soft tissue and the final prosthesis.

Marginal bone and soft tissue behavior following platform switching abutment connection/disconnection--a dog model study

OBJECTIVE

The effect on the marginal peri-implant tissues following repeated platform switching abutment removal and subsequent reconnection was studied.

MATERIAL AND METHODS

Six adult female Beagle dogs were selected, and Pm3 and Pm4 teeth, both left and right sides, were extracted and the sites healed for 3 months. At this time, 24 bone level (BL) (Straumann, Basel, Switzerland) Ø 3.3/8 mm implants were placed, 2 in each side on Pm3 and Pm4 regions. In one side (control group), 12 bone level conical Ø 3.6 mm healing abutments and, on the other side (test group), 12 Narrow CrossFit (NC) multibase abutments (Straumann) , Basel, Switzerland) were connected at time of implant surgery. On test group, all prosthetic procedures were carried out direct to multibase abutment without disconnecting it, where in the control group, the multibase abutment was connected/disconnected five times (at 6/8/10/12/14 weeks) during prosthetic procedures. Twelve fixed metal bridges were delivered 14 weeks after implant placement. A cleaning/control appointment was scheduled 6 months after implant placement. The animals were sacrificed at 9 months of the study. Clinical parameters and peri-apical x-rays were registered in every visit. Histomorphometric analysis was carried out for the 24 implants. The distance from multibase abutment shoulder to the first bone implant contact (S-BIC) was defined as the primary histomorphometric parameter.

RESULTS

Wilcoxon comparison paired test (n = 6) found no statistically significant differences (buccal P = 0.917; Lingual P = 0.463) between test and control groups both lingually and buccally for S-BIC distance. Only Pm3 buccal aBE-BC (distance from the apical end of the barrier epithelium to the first bone implant contact) (P = 0.046) parameter presented statistically significant differences between test and control groups. Control group presented 0.57 mm more recession than test group, being this difference statistically significant between the two groups (P < 0.001).

CONCLUSION

It can be conclude, within the limits of this animal study, that the connection/disconnection of platform switching abutments during prosthetic phase of implant treatment does not induce bone marginal absorption. Furthermore, it may present a negative influence in the buccal connective tissue attachment that becomes shorter anyway preventing marginal hard tissue resorption, especially in thin biotypes.

Healing at implant sites prepared conventionally or by means of Sonosurgery ®. An experimental study in dogs

OBJECTIVE

To compare peri-implant tissue healing at implants installed in sites prepared with conventional drills or a sonic device.

MATERIAL AND METHODS

In six Beagle dogs, the mandibular premolars and first molars were extracted bilaterally. After 3 months, full-thickness muco-periosteal flaps were elevated and recipient sites were prepared in both sides of the mandible. In the right side (control), the osteotomies were prepared using conventional drills, while, at the left side (test), a sonic device (Sonosurgery(®)) was used. Two implants were installed in each side of the mandible. After 8 weeks of non-submerged healing, biopsies were harvested and ground sections prepared for histological evaluation.

RESULTS

The time consumed for the osteotomies at the test was more than double compared to the conventional control sites. No statistically significant differences were found for any of the histological variables evaluated for hard and soft tissue dimensions. Although not statistically significant, slightly higher mineralized bone-to-implant contact was found at the test (65.4%) compared to the control (58.1) sites.

CONCLUSIONS

Similar healing characteristics in osseointegration and marginal hard tissue remodeling resulted at implants installed into osteotomies prepared with conventional drills or with the sonic instrument (Sonosurgery(®)).