The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.

99

Evaluation of a Porcine Collagen Matrix Used to Augment Keratinized Tissue and Increase Soft Tissue Thickness Around Existing Dental Implants Rachel A. Schallhorn, DDS, MS1 Pamela K. McClain, DDS1 Allan Charles, DDS2 Donald Clem, DDS, PhD3 Michael G. Newman, DDS4 Implant-supported prostheses often present with mucogingival deficiencies that may cause esthetic or hygienic issues. These issues may present as limited or no keratinized tissue, irregular soft tissue contour or concavity, and gray “showthrough” of the implant abutment and root forms. An interpositional soft tissue graft substitute that generates keratinized tissue and increases soft tissue thickness would be beneficial, as it would reduce donor site morbidity and be available in unlimited, off-the-shelf supply. Thirty patients were assessed as part of a multicenter, practice-based evaluation of the material. A xenogeneic collagen matrix was placed as an interpositional graft on the buccal aspect of implant sites; sites were reassessed at 6 months posttreatment. Results indicated that the collagen matrix increased tissue thickness and keratinized tissue around existing dental implants. (Int J Periodontics Restorative Dent 2015;35:99–103. doi: 10.11607/prd.1888)

Private Practice, Aurora, Colorado, USA. Private Practice, Pasadena, California, USA. 3Private Practice, Fullerton, California, USA; Adjunct Professor, University of Texas Health Science Center at San Antonio, San Antonio, Texas, USA. 4Professor Emeritus, UCLA University of California, Los Angeles School of Dentistry, Los Angeles, California, USA; Health Industry Consultant, Boston, Massachusetts, USA. 1 2

Correspondence to: Dr Rachel A. Schallhorn, 11200 E. Mississippi Ave, Aurora, CO 80012, USA; fax: 303-301-4852; email: [email protected]. ©2015 by Quintessence Publishing Co Inc.

The early diagnosis of “ailing” implants requires a multifactorial evaluation of both hard and soft tissues. The role of peri-implant soft tissue in maintaining and facilitating implant health has been evaluated; however, the research is equivocal. The need for keratinized tissue (KT) around implants has been questioned1,2; however, more recent cross-sectional studies have demonstrated that KT and peri-implant soft tissue thickness positively correlates with the health of the peri-implant tissues and clinical parameters.3,4 In addition, little or no KT along with thin soft tissues have been associated with reduced tissue health, which in turn has been associated with higher levels of bone loss.3,5,6 The conflicting evidence suggests the need for KT and increased tissue thickness around implants may be variable and patient-specific. In addition to implant health and stability, the soft tissue profile can significantly influence the esthetics of implant-supported restorations. Soft tissue deficiencies can include minimal or no KT, soft tissue concavities, and/or gray “show-through” of the implant abutment and implant.

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100 Method and materials

Fig 1    Soft tissue thickness was measured with an endodontic probe/silicone stop, inserted approximately 1.5 mm apical to the gingival margin at the midbuccal aspect of the site and sounding to bone.

Aside from creating an esthetic issue, an irregular soft tissue profile or soft tissue concavities on the facial aspect of implants may be indicative of underlying buccal bone loss. A new xenogeneic, porcine collagen matrix has been studied as a connective tissue graft (CTG) alternative for root coverage and generation of KT around teeth and implants.7–11 In these studies, increased soft tissue thickness was subjectively observed but not objectively measured. Accordingly, a multicenter pilot study was organized in three private practices to evaluate clinical outcomes at implant sites treated using the collagen matrix as an interpositional graft. Parameters evaluated include soft tissue thickness, KT width, and gray showthrough or discoloration of the facial soft tissue.

This multicenter pilot study reported on patients presenting to three clinical practices with peri-implant soft tissue deficiencies (Fullerton, California; Pasadena, California; and Aurora, Colorado—all U.S. cities). Patients were included in the study if they had implant sites with at least one of the following conditions associated with one or more existing implants: gray show-through, facial soft tissue contour deficiency or concavity, and/or KT width < 2 mm. Study patients were between the ages of 18 and 75 and were required to demonstrate effective plaque control, defined as a lack of visible plaque accumulation at the proposed surgical site, and to read and sign informed consent forms. Patients were not included if they presented with systemic healing disorders such as uncontrolled diabetes mellitus; cancer; HIV; chronic, highdose steroid therapy; bone metabolic diseases; radiation or other immunosuppressive disorders; or other conditions that may compromise wound healing. Patients also were excluded if they were pregnant or lactating, were smokers (weekly or more frequent use of any tobacco products within the last 6 months), or exhibited parafunctional habits or signs of acute, infectious lesions in the area intended for treatment. The primary outcome tested was tissue thickness at 3 and 6 months compared with baseline, as measured (1) with an endodontic probe/ silicone stop (Flex Files 25 × 25, 1 mm Silicone Stops, Dentsply), inserted approximately 1.5 mm apical

to the gingival margin (Fig 1), at the midbuccal aspect, sounding to bone and measured using a ×7 comparator with reticle (SC-7, Electro-Optix); and (2) by standardized photographic evidence of gray show-through, as designated by a blinded, thirdparty evaluator using “yes/no” designations (photo time sequences, ie, baseline, 3, or 6 months, were not provided). Secondary endpoints measured at baseline and 3 and 6 months posttreatment included the following: •









KT width using a UNC probe (UNC-12 color-coded probe, Hu-Friedy), measured at the midbuccal aspectof the implant site from the gingival margin to the mucogingival junction Recession and probing depth, using a UNC probe at the midbuccal aspect of the implant from the prosthetic margin or other designated landmark to the gingival margin and the base of the pocket, respectively Color compared with baseline, using a 3-point scale of “redder than,” “same as,” or “not as red as,” designated by a blinded, third-party examiner Contour deficiency or concavity, designated “improved,” “worsened,” or “no change” by a blinded, third-party examiner Patient satisfaction, as selfscored by patients on a visual analog scale (VAS) ranging from 0 (entirely dissatisfied) to 100 (entirely satisfied).

Photodocumentation magnification was standardized at 1:1.5, and

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101 the same camera and flash settings were used at all time points within each center. Examiners separate from the surgeons performing the procedures performed all probing measures. As this investigation was designed to be a pilot study, there was no calibration of the examiners prior to study initiation. Implant sites were used as the statistical unit of evaluation. For numerical outcomes, data were summarized by means and SDs of the entire sample of implant sites evaluated, and changes from baseline were evaluated using a Wilcoxon signed rank test. The surgical approach to prepare the wound bed was similar to an interpositional CTG technique. A gingival “pouch” was created on the buccal surface of treated implant(s) utilizing sulcular incisions extending one-half to one full tooth beyond the implant(s) and split-thickness flap reflection beyond the mucogingival junction; papillae at the mesial and distal aspects of the treated implant(s) were reflected, but no lingual reflection was done. If necessary, interdental vertical incisions were employed to gain adequate release but were not placed directly adjacent to the implant site(s). If feasible, any muscle or frenum attachments were severed and periosteum was scored apically. The collagen matrix (CM; Mucograft, Geistlich) was trimmed to cover the prepared wound bed and allowed complete coverage of the material with the mucosal flap without necessitating coronal positioning. If possible, the CM was secured using absorbable sutures either by a sling around

a

b

c

d

Fig 2    (a) Presurgical appearance of implant site no. 30 demonstrating a contour declivity. (b) Sulcular incisions were made to create a gingival pouch. (c) The CM was trimmed to fit and secured into place using absorbable sutures. (d) The existing soft tissue was positioned and sutured with absorbable sutures.

treated implants or tacking it to the lingual tissue. Care was taken to not compress or crush the CM (Fig 2). Patients were prescribed amoxicillin—2 g on the day of surgery and 1 g each day for the first 7 days following surgery. Patients were told to avoid compression of the surgical site and were instructed to rinse with chlorhexidine gluconate 0.12% oral rinse for the first week, then swab chlorhexidine at the gingival margin for the following 3 weeks. At 4 weeks, patients were instructed to resume gentle tooth brushing and interproximal cleaning and chewing at the treatment areas. All patients were maintained with full-mouth prophylaxis and calculus removal prior to treatment

and every 3 months thereafter, excluding treatment sites, which were maintained supragingivally.

Results Thirty-five implant sites (in 30 patients) were treated as part of the pilot study: 18 sites presented with gray show-through, 25 with contour deficiencies/concavities, and 21 with < 2 mm KT width. All sites were evaluated at 3 months, with 4 treatment sites and 3 patients lost to follow-up at 6 months. Healing was uneventful with no unfavorable or adverse events reported. At both 3 and 6 months, mean tissue thickness and KT width

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102

Table 1

Increase in tissue thickness and width of keratinized tissue (mean ± SD): Baseline to 6 months

Timepoint (n treatment sites)

Tissue thickness (mm)

Keratinized tissue width (mm)

∆ (0–180 d; n = 31)

1.5 ± 0.5 2.2 ± 0.8 2.2 ± 0.9 0.7 ± 0.8

1.7 ± 1.8 2.6 ± 2.0 2.1 ± 1.0 0.7 ± 1.2

P ∆ (0–180 d)

< .0001

.0016

Baseline (n = 35) 3 mo (n = 35) 6 mo (n = 31)

a

b

Recession depth (mm) 1.5 ± 1.5 1.5 ± 1.5 1.5 ± 1.4 –0.1 ± 0.7

c

Fig 3    Healing of surgically treated site no. 30 at (a) 1, (b) 3, and (c) 6 months, respectively. Fig 4    Surgically treated site no. 30 demonstrating a contour declivity at (a) pretreatment baseline and (b) 6 months posttreatment.

a

a

a

b

had statistically significant increases, and probing depths were reduced significantly (Table 1). There was no

3.5 ± 1.7 3.1 ± 1.4 3.0 ± 1.6 –0.5 ± 1.0 .0042

As scored by the blinded examiner, color comparison to baseline stayed the same for 29 sites and was improved (less red) for the remaining two patients. Although not statistically significant, improvements in gray show-through and facial soft tissue contour were observed for 14 and 11 patients, respectively (P = .5413 and .8388).

Discussion

b

b

.3809

Pocket depth (mm)

Fig 5    Surgically treated site no. 2 demonstrating a lack of KT and slight marginal soft tissue recession at (a) pretreatment baseline and (b) 6 months posttreatment demonstrating soft tissue coverage of the crown-abutment junction.

Fig 6    Surgically treated site no. 12 demonstrating buccal soft tissue contour declivity and grey showthrough at (a) pretreatment baseline and (b) 6 months posttreatment, demonstrating improved soft tissue contour and reduced grey show-through.

significant change in mean recession over the course of the study (Figs 3a, 3b, and 3c).

The multicenter pilot study was designed to evaluate the efficacy of using a porcine CM as an interpositional graft to increase soft tissue thickness and KT around preexisting dental implants. At baseline, the treated implant sites exhibited soft tissue deficiencies the investigators considered esthetically unappealing and potentially predictive of an increased risk for development of peri-implant mucositis or peri-implantitis. Results among centers were similar. Overall, the CM procedure produced a statistically significant gain in gingival thickness and KT, but results between implant sites were variable. Some sites were only marginally improved, whereas others

The International Journal of Periodontics & Restorative Dentistry © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.

103 achieved soft tissue thickness and KT width gains of up to 2 mm (Figs 3 to 6). No common or underlying factors were correlated with the outcome variability. While statistically significant gains in gingival thickness and KT were observed, no significant changes in gray show-through or soft tissue contour were found; however, trends toward improvement in both endpoints were identified and warrant additional research with well-defined parameters for standardized evaluation and scoring. The patients’ mean VAS score for satisfaction was 90 ± 20 on a 0 to 100 “satisfaction” scale, and two patients reported reduced site sensitivity after treatment, with one patient no longer requiring local anesthesia during periodontal maintenance. However, patients were not required to pay for their treatments, so the balance of economic value versus patient benefit was not tested. Due to the thickness of the CM and the pouch technique employed, CM placement without compression was difficult. More extensive flap reflection and coronal positioning may improve both surgical access and treatment outcomes. Layering CM, modifying the CM design as has recently been evaluated in an animal model,12 and using biologic modifiers such as growth factors may also be beneficial.13 Alternatively, using CM proactively at the time of implant placement, rather than later when soft tissue problems develop, also may be considered for future evaluation. Regardless, a well-designed, multicenter, randomized clinical trial should be imple-

mented to evaluate the value of any graft substitute or surgical technique employed in this indication.

Conclusions CM demonstrated the potential to increase KT and tissue thickness around existing dental implants. The technique and material tested provided variable results with empirically lower predictability than autogenous CTG, and it was unclear why some cases were more successful than others. Improved surgical access and placement of CM at the time of implant placement might be beneficial. Additional research is needed to confirm and expand the results in this multicenter case series.

Acknowledgments The authors would like to thank Geistlich Pharma for providing product samples and support for patients entered in the study. All other costs were incurred by the authors, who declare no conflicts of interest.

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 4. Zigdon H, Machtei EE. The dimensions of keratinized mucosa around implants affect clinical and immunological parameters. Clin Oral Implants Res 2008;19:387–392.   5. Chung DM, Oh TJ, Shotwell JL, Misch CE, Wang HL. Significance of keratinized mucosa in maintenance of dental implants with different surfaces. J Periodontol 2006;77: 1410–1420.   6. Fürhauser R, Florescu D, Benesch T, Haas R, Mailath G, Watzek G. Evaluation of soft tissue around single-tooth implant crowns: The pink esthetic score. Clin Oral Implants Res 2005;16:639–644.  7. Sanz M, Lorenzo R, Aranda JJ, Martin C, Orsini M. Clinical evaluation of a new collagen matrix (Mucograft prototype) to enhance the width of keratinized tissue in patients with fixed prosthetic restorations: A randomized prospective clinical trial. J Clin Periodontol 2009;36:868–876.  8. Herford AS, Akin L, Cicciu M, Maiorana C, Boyne, PJ. Use of a porcine collagen matrix as an alternative to autogenous tissue for grafting oral soft tissue defects. J Oral Maxillofac Surg 2010;68:1463– 1470.  9. McGuire MK, Scheyer ET. Xenogeneic collagen matrix with coronally advanced flap compared to connective tissue with coronally advanced flap for the treatment of dehiscence-type recession defects. J Periodontol 2010;81:1108–1117. 10. Cardaropoli D, Tamagnone L, Roffredo A, Gaveglio L. Treatment of gingival recession defects using coronally advanced flap with a porcine collagen matrix compared to coronally advanced flap with connective tissue graft: A randomized controlled clinical trial. J Periodontol 2012;83:321–328. 11. Mandelaris GA, Lu M, Rosenfeld AL. The use of a xenogeneic collagen matrix as an interpositional soft-tissue graft to enhance peri-implant soft-tissue outcomes: A clinical case report and histologic analysis. Clin Adv Periodontics 2011;1:193– 198. 12. Thoma DS, Jung RE, Schneider D, et al. Soft tissue volume augmentation by the use of collagen-based matrices: A volumetric analysis. J Clin Periodontol 2010; 37:659–666. 13. Herford AS, Lu M, Akin L, Cicciu M. Evaluation of a porcine matrix with and without platelet-derived growth factor for bone graft coverage in pigs. Int J Oral Maxillofac Implants 2012;27:1351–1358.

Volume 35, Number 1, 2015 © 2015 BY QUINTESSENCE PUBLISHING CO, INC. PRINTING OF THIS DOCUMENT IS RESTRICTED TO PERSONAL USE ONLY. NO PART MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM WITHOUT WRITTEN PERMISSION FROM THE PUBLISHER.

Evaluation of a porcine collagen matrix used to augment keratinized tissue and increase soft tissue thickness around existing dental implants.

Implant-supported prostheses often present with mucogingival deficiencies that may cause esthetic or hygienic issues. These issues may present as limi...
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