Prof Anton Friedmann : Pioneer in Periodontal Regeneration with Hyaluronic Acid

Prof anton friedmannRegedent, caught up with Prof. Anton Friedmann to find out more about his clinical experience with cross-linked hyaluronic acid and the CLEAN&SEAL therapy. The CLEAN&SEAL concept provides guidance and support for the treatment and control of peri-implant mucositis.

Prof. Anton Friedmann is the head of the department of Periodontology at the School of Dentistry of the Witten/Herdecke University (Germany). He has several years of experience clinically and scientifically in using cross-linked hyaluronic acid gel (hyaDENT BG) and sodium hypochlorite (Perisolv) as part of the CLEAN&SEAL therapeutical protocol.

Read the full interview below.

Prof Anton Friedmann : Interview about cross-linked hyaluronic acid in periodontology

Thank you for taking the time to speak to us, Prof. Friedmann. You have been using cross-linked hyaluronic acid in periodontology for several years now as part of the CLEAN&SEAL Therapy.

Question 1: What clinical advantages do you see when using sodium hypochlorite gel and cross-linked hyaluronic acid gel in periodontal treatment?

Prof Anton Friedmann : “When considering persistent situations of deep pocket sites, maybe even recurrent sites, that do not respond properly to our subgingival instrumentation, I clearly recognize the benefits in applying both, the Perisolv (sodium hypochlorite+ amino acid gel) and the xHyA (cross-linked hyaluronic acid gel) to enhance the effect of subgingival instrumentation.

The first one helps us to decontaminate the wound area and the root surface. It also, has an effect on the granulation tissue. We already know it affects granulation tissue effectively. So far, what we see is that the efficacy of the debridement is improved. We than fill the pocket with the cross-linked hyaluronic acid because it stabilizes the blood clot and facilitates regeneration. The benefits are multiple. It is not just one or two effects we are talking about any more.”

Question 2: Can you tell us a bit more about your clinical experience in applying the CLEAN&SEAL therapy?

Prof Anton Friedmann : “The clinical experience we have, this is not just limited to my experience, but represents the experience of our entire group because my co-workers are also using CLEAN&SEAL and cross-linked Hyaluronic Acid as well. Some of the outcomes that we are seeing are: easily reducing pocket depth (PPD) in persistent pockets and these effects are accompanied with gain in CAL. We also clearly see confirmation of these changes on the radiographs that we take around 12 months after the procedure.”

Question 3: What do you foresee for the future. Do you think that the CLEAN&SEAL could possibly become a routine periodontal treatment solution?

Prof Anton Friedmann : “We have started an RCT study for the treatment. Once we have the results for this RCT study, we will be able to foresee if it can be applied as a routine treatment for various indications.”

Question 4: Do you see any advantages in to use of the CLEAN&SEAL therapy on surgical and non-surgical applications?

Prof Anton Friedmann : “We know that cross-linked hyaluronic acid helps significantly with periodontal regeneration. This is for example seen in intrabony defects. I think Perisolv may also support the effect. Maybe not as strong as if applied non-surgically, but we don’t have data to support that yet. We are currently collecting more evidence on Clean & Seal. In fact, I do treat periimplantitis defects with the CLEAN&SEAL, there I can tell, it does have a tremendous impact in using both, Perisolv and cross-linked hyaluronic acid for regenerative response in treating infrabony defect at implants.”


Prof Anton Friedmann : Webinar & Lectures

Lecture n°1

The congress Europerio 10 in Copenhagen highlighted effective pocket closure in persistent active periodontal pockets: the CLEAN&SEAL concept at subgingival instrumentation

Abstract – The lecture considers the strategy for treating residual deep periodontal sites with and without the signs of inflammation, during supportive periodontal treatment with the repeated use of subgingival instrumentation in sites exceeding 4 mm in probing depth (PPD) associated with bleeding and those over 6 mm PPD. This approach, effectively contributes to tooth maintenance. It is known that the persistence of high PPD values is associated with a statistically upraised risk of loosing teeth in the long-term.

Locally administered adjunctive products (e.g., local antibiotics, photodynamic therapy, antiseptics) mostly focuses on improving the biofilm control targeting thereby the pocket closure rate. Addressing down regulation of the inflammatory status of periodontal tissues the products supposed to effectively control the biofilm formation. Studies reveal that the anti-inflammatory effect of these adjunctive solutions does not necessarily change the residual PPD in the long-term. Recently introduced, non-surgical use of amelogenins intends to exaggerate the regenerative capacity of cells involved in the tissue formation.

The CLEAN&SEAL treatment concept relies on the adjunctive use of two independent components. First, the Hypochlorite gel as the supportive cleaning agent for the efficient biofilm removal. Subsequently, the subgingival administration of a crosslinked Hyaluronic Acid (xHyA) gel for the enhancement of biological pocket closure. Both biologics are effective antimicrobials. The Hypochlorite gel complements the subgingival instrumentation by additional decontamination and the xHyA gel promotes wound healing and additional clinical attachment level formation over time. The purpose of this presentation, is to share the improvements in clinical parameters and radiographic controls our group experienced at sites, which previously persisted with a long history of non-responding to subgingival instrumentation despite patient’s regular SPT program participation.

Webinar n°1

The adjunctive potential of hyaluronic acid in regenerating periodontal tissues 

Abstract – As indicated in the first part of the webinar, the Clean and Seal concept applied within the surgical treatment stage is credited effective in the therapy of peri-implant infrabony defects. 

This part of the webinar focuses on the results of the non-surgical and surgical application of hyaDENT BG in periodontal infrabony defects. 

A very recent randomized clinical study compared the effects of cross-linked hyaluronic acid (cHA) to that of EMD applied in infrabony periodontal defects during minimally invasive surgery. At 12 and 24 months the clinical results were statistically superior to the baseline values for both materials, respectively. Our group combined the use of xHyA  with various bone substitutes, xenografts or alloplasts either with or without a synthetic or collagen membrane in the surgical treatment of infrabony periodontal defects. Today, we overlook a case series with more than 20 patients and over 25 initially severely compromised teeth. The clinical and radiographical documentation of the outcomes regarding the clinical attachment level gain and change in bone fill are really impressive. 

The most impressive clinically relevant improvement was radiographically revealed in those sites, which we treated with cHA alone or cHA combined just with a membrane applied for secluding the soft tissues in infrabony defects before suture. The combination of a synthetic resorbable bone substitute and cHA applied without membranes proved also successful. Our clinical outcomes will be discussed in light of the before-mentioned results from an RCT trial and recently introduced pre-clinical histo-morphometric study in dogs.

Webinar n°2

Tackling peri implant defects – Cleaning and empowering healing with Prof Anton Friedmann

The CLEAN&SEAL therapeutical concept is set to enhance the outcomes in non-surgical therapy of mucositis and shallow peri-implantitis. The approach combines subsequently the mechanical instrumentation of the implant surfaces with chemical debridement supported by application of the gel combining sodium hypochlorite with amino acids(chloramines) into the peri-implant pockets. After the cleaning with instruments and the gel, the pocket is sealed by applying the cross-linked hyaluronic acid.

The efficacy of the concept in treating mucositis was clinically documented and clinical trials comparing this therapy with simple mechanical treatment are available. The latest published study focused on the biological impact of cross-linked hyaluronic acid (xHyA) gel on periodontal regeneration. Both, a pre-clinical study and an RCT trial clearly confirmed the significant contribution of xHyA to the formation of new periodontal attachment histomorphometrically and clinically. The therapy of deep peri-implant infrabony defects requires a surgical approach to be successful in reducing the inflammation and supporting the concomitant new peri-implant bone formation.

Therefore, we support the combination of the hypochlorite with cross-linked hyaluronic acid both applied in an open flap access extended by GBR (Guided Bone Regeneration) for regeneration of the missing bone attachment. The grafting material introduced for this purpose is a xenograft of porcine origin. The reliable evidence from the pre-clinical trials and human histological observations proved the probability of xenograft to ossify.

In a series of clinical cases applying surgical CLEAN&SEAL and the GBR concept, we regularly observe the reconstitution of missing peri-implant bone attachment at radiographic level after a healing period of 6 to 12 months. The reconstructed sites appear clinically healthy without signs of bleeding and the patients report valuable desensitization of marginal mucosa by masticatory loading and at performing oral hygiene procedure.


Prof Anton Friedmann: Publications in relation to cross-linked hyaluronic acid gel

  • Diehl, D.; Friedmann, A.; Liedloff, P.; Jung, R.M.; Sculean, A.; Bilhan, H. Adjunctive Application of Hyaluronic Acid in Combination with a Sodium Hypochlorite Gel for Non-Surgical Treatment of Residual Pockets Reduces the Need for Periodontal Surgery Retrospective Analysis of a Clinical Case Series. Materials 2022, 15, 6508.
  • Nobis, B.; Ostermann, T.; Weiler, J.; Dittmar, T.; Friedmann, A. Impact of Cross-Linked Hyaluronic Acid on Osteogenic Differentiation of SAOS-2 Cells in an Air-Lift Model. Materials 2022, 15, 6528. https://
  • Bilhan H, Friedmann A. The “Tunneled Sandwich” Technique for Preserving the Buccal Tissue Volume After Immediate Implantation: A Retrospective Report of 10 Cases. Int J Periodontics Restorative Dent. 2023 Oct 24;(7):s53-s64. doi: 10.11607/prd.6205. PMID: 37294593.
  • Husseini B, Friedmann A, Wak R, Ghosn N, Khoury G, El Ghoul T, Abboud CK, Younes R. Clinical and radiographic assessment of cross-linked hyaluronic acid addition in demineralized bovine bone based alveolar ridge preservation: A human randomized split-mouth pilot study. J Stomatol Oral Maxillofac Surg. 2023 Sep;124(4):101426. doi: 10.1016/j.jormas.2023.101426. Epub 2023 Feb 16. PMID: 36801259.
  • Friedmann, Anton & Goetz, Werner. (2022). Combined Sinus Grafting and Lateral Augmentation by a Hyaluronic Acid-Facilitated Guided Bone Regeneration Protocol – Case Series Supported by Human Histologic Analysis. Journal of Biomedical Research & Environmental Sciences. 3. 065-073. 10.37871/jbres1401.
  • Friedmann, Anton & Goetz, Werner. (2020). Hyaluronsäure in der Regeneration parodontaler und ossärer Gewebe. Quintessenz.71.6.20