Healing of buccal gingival recessions following treatment with coronally advanced flap alone or combined with a cross-linked hyaluronic acid gel. An experimental study in dogs

Local application of 0.8% hyaluronic acid gel as an adjunct to minimally invasive nonsurgical treatment of periodontal intrabony defects-A randomized clinical trial

AIM

The aim of this study was to evaluate the clinical and radiographic effects of hyaluronic acid (HA) gel application as an adjunct to minimally invasive nonsurgical treatment (MINST) in intrabony defects ≥3 mm.

METHODS

A total of 36 patients were included and randomly assigned to two groups: (a) MINST + HA (test; n = 17) and (b) MINST (control, n = 19). Subgingival 0.8% HA gel was applied in intrabony defects of test group and repeated 4 weeks following MINST protocol. Clinical measurements including probing depth (PD), clinical attachment level (CAL), and gingival recession (GR) were recorded at baseline and repeated at 3 and 6 months. Radiographic evaluation was performed at baseline and 6 months.

RESULTS

Test group showed significantly greater reduction in PD and gain in CAL at 3 months compared to baseline than that of controls (p < .05), but the changes (Δ) at 6 months compared to baseline did not differ between the groups (p > .05). Although, both groups showed statistically significant GR in all evaluated time periods (p < .05), control group showed higher ΔGR than that of test group (p < .05). There was no significant difference between the groups in terms of radiographic defect fill/bone gain (p > .05).

CONCLUSIONS

The additional use of 0.8% HA gel in the treatment of periodontal intrabony defects did not provide additional benefits in clinical and radiographic parameters. On the other hand, GR measurements showed favorable results in the test group.

Advancements in Hyaluronic Acid Effect in Alveolar Ridge Preservation: A Narrative Review

Background/Objectives: Tooth extraction induces significant alveolar ridge dimensional changes and soft tissue modifications, often leading to challenges in implant placement or conventional prosthetic rehabilitation. Alveolar Ridge Preservation (ARP) strategies aim to mitigate post-extraction resorption of the alveolar ridge, enhancing both the quality and quantity of bone and soft tissue during healing. Hyaluronic acid (HYA) has emerged as a promising biological agent for ARP due to its osteoinductive, antimicrobial, and anti-inflammatory properties. However, the effects of HYA in ARP remain inconsistently reported. This study aims to assess current clinical and preclinical evidence regarding the biological effects of HYA and its application in ARP. Additionally, it evaluates HYA's impact-alone or in combination with other products-on hard and soft tissue dimensional changes, early wound healing, and implant success rates. Methods: A comprehensive electronic literature search was conducted, and studies meeting the inclusion criteria were critically evaluated. Relevant data were extracted from the final selection of articles. Results: Thirteen publications were evaluated. Some studies reported a significantly improved newly formed bone following ARP with intra-socket HYA application as a single approach (p = 0.004). Combining HYA with a bone graft and a free palatal graft resulted in significantly greater amounts of newly formed and mature bone, reduced clinical bone width changes, lower radiographic crestal bone loss (p < 0.01), and diminished radiological volumetric and linear bone resorption (p = 0.018). Short-term follow-up data indicated improved soft tissue healing associated with HYA-based ARP. While HYA appears to have a protective effect on ridge dimensional changes in ARP, other studies reported no significant differences in radiographic bone dimensional changes or soft tissue improvement. Conclusions: The addition of HYA to bone grafts may enhance some ARP outcomes. However, the variability in outcomes and methodologies across the evaluated studies precludes drawing definitive clinical conclusions. Further robust research is needed to clarify HYA's role in ARP. With respect to clinical significance enhancing the understanding of ARP management strategies and their effects on post-extraction sockets empowers clinicians to make more informed decisions. The knowledge of HYA effects facilitates the selection of personalized ARP approaches tailored to optimize outcomes for subsequent interventions.

RNA Sequencing Revealed a Weak Response of Gingival Fibroblasts Exposed to Hyaluronic Acid

Hyaluronic acid was proposed to support soft tissue recession surgery and guided tissue regeneration. The molecular mechanisms through which hyaluronic acid modulates the response of connective tissue cells remain elusive. To elucidate the impact of hyaluronic acid on the connective tissue cells, we used bulk RNA sequencing to determine the changes in the genetic signature of gingival fibroblasts exposed to 1.6% cross-linked hyaluronic acid and 0.2% natural hyaluronic acid. Transcriptome-wide changes were modest. Even when implementing a minimum of 1.5 log2 fold-change and a significance threshold of 1.0 -log10, only a dozenth of genes were differentially expressed. Upregulated genes were PLK3, SLC16A6, IL6, HBEGF, DGKE, DUSP4, PTGS2, FOXC2, ATAD2B, NFATC2, and downregulated genes were MMP24 and PLXNA2. RT-PCR analysis supported the impact of hyaluronic acid on increasing the expression of a selected gene panel. The findings from bulk RNA sequencing suggest that gingival fibroblasts experience weak changes in their transcriptome when exposed to hyaluronic acid.

Sequential Bone Repair in Rabbit Sinus Lifts Using Bio-Oss and Hyaluronic Acid-Polynucleotide Gel (Regenfast)

BACKGROUND

A comprehensive investigation to associate the use of polynucleotides and hyaluronic acid with bovine bone in maxillary sinus lift procedures in rabbits has not been performed yet. The aim was to evaluate the influence of this novel association on the processes of bone regeneration in maxillary sinus augmentation.

METHODS

In this prospective, randomized, within-animal model, maxillary sinus augmentation was performed bilaterally in 12 rabbits. Deproteinized bovine bone material (DBBM) was used as filler material. A hyaluronic acid-polynucleotide gel was aggregated at the test site. Histological evaluations were performed after 2 and 10 weeks of healing.

RESULTS

After 2 weeks of healing, similar amounts of new bone were observed at both the control (7.7 ± 4.3%) and test sites (8.1 ± 3.8%; p = 0.697). Bone formation was observed predominantly along the osteotomy margins and adjacent sinus walls. After 10 weeks of healing, the total new bone fraction reached 28.0 ± 10.1% at the control sites and 27.3 ± 10.5% at the test sites (p = 0.563). Multiple perforations of the sinus mucosa were observed in both groups when in contact with the biomaterial granules.

CONCLUSION

The present study failed to demonstrate a positive effect on bone formation when incorporating hyaluronic acid-polynucleotide gel (Regenfast) into a xenograft for maxillary sinus augmentation. Additionally, the use of this gel did not mitigate the occurrence of thinned mucosa or reduce the risk of subsequent sinus mucosa perforation.

Tunnel technique and subepithelial connective tissue graft, with or without cross-linked hyaluronic acid, in the treatment of multiple gingival recessions: 12-month outcomes of a randomized clinical trial

BACKGROUND

This study evaluated the influence of the adjunctive application of a cross-linked hyaluronic acid (HA) in the treatment of multiple gingival recessions, using a modified coronally advanced tunnel (MCAT) technique and subepithelial connective tissue graft (SCTG) (MCAT+SCTG±HA).

METHODS

A randomized, split-mouth, double-masked comparison of the effects of MCAT+HA+SCTG (test) versus MCAT+SCTG (control) in the treatment of multiple, contralateral gingival recessions with clinical, esthetic, and histological evaluations was carried out. All samples were stained with hematoxylin and eosin, Masson's trichrome, Verhoeff-Van Gieson, and Alcian blue stain for semiquantitative evaluation. The primary outcome variable was 12-month mean root coverage (MRC).

RESULTS

Twenty-four patients with 266 gingival recessions received both control and test treatments (133 recessions per group). 12-month MRC of the MCAT+HA+SCTG group was not significantly different from the MCAT+SCTG group with 84.32%±  34.46% and 85.71%±  36.43%, respectively (p = 0.991). Both treatment modes produced favorable esthetic outcomes (root coverage esthetic score [RES] 9.51±  1.01 tests vs. 9.26±  1.10 controls, p = 0.7292). However, the application of HA improved soft tissue texture (p = 0.0091). The remaining end point measures did not differ significantly between groups. Histological evaluation showed a significantly greater number of elastic fibers and a moderate increase in collagen fiber density in biopsy samples taken from the test sides when compared to the control sides (p = 0.0419 and p = 0.300, respectively).

CONCLUSIONS

MCAT+SCTG is an effective procedure in the treatment of multiple recession Type 1 (RT1) and RT2 recessions. There were no statistically significant differences in evaluated clinical treatment outcomes in the MCAT+HA+SCTG group compared to the MCAT+SCTG group within a period of 12 months. The application of HA increased collagen and elastic fiber density.

Non-surgical treatment of residual periodontal pockets using sodium hypochlorite/amino acid gel and cross-linked hyaluronic acid-a 9-month pilot randomized controlled clinical trial

OBJECTIVES

This pilot randomized controlled clinical trial compares the clinical outcome obtained in persistent periodontal pockets during 9-month follow-up of supportive periodontal step 4 treatment performed by either combining subgingival instrumentation with adjunctively used sodium hypochlorite/amino acid gel and crosslinked hyaluronic acid (xHyA) or subgingival instrumentation alone.

MATERIALS AND METHODS

Study protocol is registered under NCT06438354 at Clinicaltrials.gov. Patients seeking further therapy after completed step 2 non-surgical periodontal treatment underwent either repeated subgingival instrumentation with adjunctive application of sodium hypochlorite/amino acid gel and crosslinked hyaluronic acid (group A) or repeated subgingival instrumentation alone (group B). One calibrated investigator performed the treatment sequence in both groups accordingly. Subgingival instrumentation of the residual pockets was carried out under local anaesthesia using hand- and ultrasonic instruments, as well as air polishing in both groups. Patients were instructed to continue oral hygiene without any restriction. At 3-month re-evaluation treatment was repeated accordingly at sites with persistent 5 mm probing depth and BoP + . Clinical attachment level (CAL), pocket probing depth (PPD), gingival recession (GR), and bleeding on probing (BoP) were recorded at baseline (T1), 3- (T2) and 9-month (T3) post-op, with CAL as a primary outcome measure.

RESULTS

In total 52 patients (20 females and 32 males, mean age 58.4 ± 2.4 years) presenting with 1448 sites which required further periodontal treatment were enrolled. Both groups exhibited homogeneity in terms of age, gender, smoking habit, initial number of sites, and BOP. At 9-month evaluation, PD reduction and CAL gain showed significant differences between the test and control group, favouring the adjunctive treatment. GR tended to exhibit more recovery in the test group compared to the control group. Although BOP frequency effectively reduced in both groups, there was no statistically significant difference between the two groups.

CONCLUSION

Within the limits of the study, the present data indicates that, during subgingival instrumentation of persistent pockets, the adjunctive usage of sodium hypochlorite/amino acid gel and xHyA sufficiently improves the clinical outcomes. The continuous improvement of CAL in association with the GR scores observed in group A, indicates that sites subjected to adjunctive treatment may indicate a tendency for a regenerative response to treatment within the 9-month follow-up period.

Microbiological Effects of Sodium Hypochlorite/-Amino Acids and Cross-linked Hyaluronic Acid Adjunctive to Non-surgical Periodontal Treatment

PURPOSE

To investigate the microbiological outcomes obtained with either subgingival debridement (SD) in conjunction with a gel containing sodium hypochlorite and amino acids followed by subsequent application of a cross-linked hyaluronic acid gel (xHyA) gel, or with SD alone.

MATERIALS AND METHODS

Forty-eight patients diagnosed with stages II-III (grades A/B) generalised periodontitis were randomly treated with either SD (control) or SD plus adjunctive sodium hypochlorite/amino acids and xHyA gel (test). Subgingival plaque samples were collected from the deepest site per quadrant in each patient at baseline and after 3 and 6 months. Pooled sample analysis was performed using a multiplex polymerase chain reaction (PCR)-based method for the identification of detection frequencies and changes in numbers of the following bacteria: Aggregatibacter actinomycetemcomitans (A.a), Porphyromonas gingivalis (P.g), Tannerella forsythia (T.f), Treponema denticola (T.d), and Prevotella intermedia (P.i).

RESULTS

In terms of detection frequency, in the test group, statistically significant reductions were found for P.g, T.f, T.d and P.i (p < 0.05) after 6 months. In the control group, the detection frequencies of all investigated bacterial species at 6 months were comparable to the baseline values (p > 0.05). The comparison of the test and control groups revealed statistically significant differences in detection frequency for P.g (p = 0.034), T.d (p < 0.01) and P.i (p = 0.02) after 6 months, favouring the test group. Regarding reduction in detection frequency scores, at 6 months, statistically significant differences in favour of the test group were observed for all investigated bacterial species: A.a (p = 0.028), P.g (p = 0.028), T.f (p = 0.004), T.d (p <0.001), and P.i (p = 0.003).

CONCLUSIONS

The present microbiological results, which are related to short-term outcomes up to 6 months post-treatment, support the adjunctive subgingival application of sodium hypochlorite/amino acids and xHyA to subgingival debridement in the treatment of periodontitis.

Histological evaluation of nonsurgical periodontal treatment with and without the use of sodium hypochlorite / amino acids and cross-linked hyaluronic acid gels in dogs

OBJECTIVES

To evaluate periodontal wound healing following scaling and root planing (SRP) in conjunction with the application of sodium hypochlorite/amino acids and cross-linked hyaluronic acid (xHyA) gels in dogs.

MATERIALS AND METHODS

In four beagle dogs, 2-wall intrabony defects were created and metal strips were placed around the teeth. Clinical parameters were measured 4 weeks after plaque accumulation. The experimental root surfaces were subjected to SRP with either the subgingival application of a sodium hypochlorite/amino acid gel and a xHyA gel (test group) or SRP alone (control group) using a split-mouth design. Clinical parameters were re-evaluated at 6 weeks. The animals were sacrificed at 8 weeks for histological analysis.

RESULTS

The test group showed significant improvements in all clinical parameters compared to the control group. Histologically, the test group exhibited statistically significantly greater new bone formation [i.e., length of newly formed bone, new bone area] compared with the control group (p < 0.05). Furthermore, statistically significantly greater formation of new attachment [i.e., linear length of new cementum adjacently to newly formed bone with inserting collagen fibers] and new cementum was detected in the test group compared with the control group at 8 weeks (p < 0.05 and p < 0.01, respectively).

CONCLUSION

The adjunctive subgingival application of sodium hypochlorite/amino acid and xHyA gels to SRP offers an innovative novel approach to enhance periodontal wound healing/regeneration.

CLINICAL RELEVANCE

The present findings have for the first-time shown histologic evidence for periodontal regeneration in support of this novel treatment modality.

Hyaluronic acid in Dentoalveolar regeneration: Biological rationale and clinical applications

Background

Hyaluronic acid (HA) is found in different locations in the periodontium, including mineralized tissues (i.e., cementum and alveolar bone) and non-mineralized tissues (i.e., gingiva and periodontal ligament). In addition, it seems to play an essential part in regulating the underlying mechanisms involved in tissue inflammatory reactions and wound healing. HA has the potential to regulate periodontal tissue regeneration and treat periodontal disease.

Aim

The current review of the literature was conducted to assess how HA plays its part in periodontal therapy and examine the contemporary literature's viewpoint on its use in periodontal regeneration.

Conclusion

HA has a multifunctional character in periodontal regeneration, and healing and appears to provide promising outcomes in different periodontal regenerative applications.

Reconstructive Approach in Residual Periodontal Pockets with Biofunctionalized Heterografts-A Retrospective Comparison of 12-Month Data from Three Centers

The regenerative capacity of well-preserved blood clots may be enhanced by biologics like enamel matrix derivative (EMD). This retrospective analysis compares outcomes reported by three centers using different heterografts. Center 1 (C1) treated intrabony defects combining cross-linked high-molecular-weight hyaluronic acid (xHyA) with a xenograft; center 2 (C2) used EMD with an allograft combination to graft a residual pocket. Center 3 (C3) combined xHyA with the placement of a resorbable polymer membrane for defect cover. Clinical parameters, BoP reduction, and radiographically observed defect fill at 12-month examination are reported. The 12-month evaluation yielded significant improvements in PPD and CAL at each center (p < 0.001, respectively). Analyses of Covariance revealed significant improvements in all parameters, and a significantly greater CAL gain was revealed for C2 vs. C1 (p = 0.006). Radiographic defect fill presented significantly higher scores for C2 and C3 vs. C1 (p = 0.003 and = 0.014; C2 vs. C3 p = 1.00). Gingival recession increased in C1 and C3 (p = 1.00), while C2 reported no GR after 12 months (C2:C1 p = 0.002; C2:C3 p = 0.005). BoP tendency and pocket closure rate shared similar rates. Within the limitations of the study, a data comparison indicated that xHyA showed a similar capacity to enhance the regenerative response, as known for EMD. Radiographic follow-up underlined xHyA's unique role in new attachment formation.

Hyaluronic acid enhances cell migration, viability, and mineralized tissue-specific genes in cementoblasts

BACKGROUND/OBJECTIVES

It has been repeatedly demonstrated that cementum formation is a crucial step in periodontal regeneration. Hyaluronic acid (HA) is an important component of the extracellular matrix which regulates cells functions and cell-cell communication. Hyaluronic acid/derivatives have been used in regenerative periodontal therapy, but the cellular effects of HA are still unknown. To investigate the effects of HA on cementoblast functions, cell viability, migration, mineralization, differentiation, and mineralized tissue-associated genes and cementoblast-specific markers of the cementoblasts were tested.

MATERIALS AND METHODS

Cementoblasts (OCCM-30) were treated with various dilutions (0, 1:2, 1:4, 1:8, 1:16, 1:32, 1:64, 1:128) of HA and examined for cell viability, migration, mineralization, and gene expressions. The mRNA expressions of osteocalcin (OCN), runt-related transcription factor 2 (Runx2), bone sialoprotein (BSP), collagen type I (COL-I), alkaline phosphatase (ALP), cementum protein-1 (CEMP-1), cementum attachment protein (CAP), and small mothers against decapentaplegic (Smad) -1, 2, 3, 6, 7, β-catenin (Ctnnb1) were performed with real-time polymerase chain reaction (RT-PCR). Total RNA was isolated on days 3 and 8, and cell viability was determined using MTT assay on days 1 and 3. The cell mineralization was evaluated by von Kossa staining on day 8. Cell migration was assessed 2, 4, 6, and 24 hours following exposure to HA dilutions using an in vitro wound healing assay (0, 1:2, 1:4, 1:8).

RESULTS

At dilution of 1:2 to 1:128, HA importantly increased cell viability (p < .01). HA at a dilution of 1/2 increased wound healing rates after 4 h compared to the other dilutions and the untreated control group. Increased numbers of mineralized nodules were determined at dilutions of 1:2, 1:4, and 1:8 compared with control group. mRNA expressions of mineralized tissue marker including COL-I, BSP, RunX2, ALP, and OCN significantly improved by HA treatments compared with control group both on 3 days and on 8 days (p < .01). Smad 2, Smad 3, Smad 7, and β-catenin (Ctnnb1) mRNAs were up-regulated, while Smad1 and Smad 6 were not affected by HA administration. Additionally, HA at dilutions of 1:2, 1:4, and 1:8 remarkably enhanced CEMP-1 and CAP expressions in a dilution- and time-dependent manner (p < .01).

CONCLUSIONS

The present results have demonstrated that HA affected the expression of both mineralized tissue markers and cementoblast-specific genes. Positive effects of HA on the cementoblast functions demonstrated that HA application may play a key role in cementum regeneration.

Hyaluronic acid in tooth extraction: a systematic review and meta-analysis of preclinical and clinical trials

OBJECTIVES

To assess whether in animals or patients with ≥ 1 tooth extracted, hyaluronic acid (HyA) application results in superior healing and/or improved complication management compared to any other treatment or no treatment.

MATERIALS AND METHODS

Three databases were searched until April 2022. The most relevant eligibility criteria were (1) local application of HyA as adjunct to tooth extraction or as treatment of alveolar osteitis, and (2) reporting of clinical, radiographic, histological, or patient-reported data. New bone formation and/or quality were considered main outcome parameters in preclinical studies, while pain, swelling, and trismus were defined as main outcome parameters in clinical studies.

RESULTS

Five preclinical and 22 clinical studies (1062 patients at final evaluation) were included. In preclinical trials, HyA was applied into the extraction socket. Although a positive effect of HyA was seen in all individual studies on bone formation, this effect was not confirmed by meta-analysis. In clinical studies, HyA was applied into the extraction socket or used as spray or mouthwash. HyA application after non-surgical extraction of normally erupted teeth may have a positive effect on soft tissue healing. Based on meta-analyses, HyA application after surgical removal of lower third molars (LM3) resulted in significant reduction in pain perception 7 days postoperatively compared to either no additional wound manipulation or the application of a placebo/carrier. Early post-operative pain, trismus, and extent of swelling were unaffected.

CONCLUSIONS

HyA application may have a positive effect in pain reduction after LM3 removal, but not after extraction of normally erupted teeth.

CLINICAL RELEVANCE

HyA application may have a positive effect in pain reduction after surgical LM3 removal, but it does not seem to have any impact on other complications or after extraction of normally erupted teeth. Furthermore, it seems not to reduce post-extraction alveolar ridge modeling, even though preclinical studies show enhanced bone formation.

Clinical evaluation of sodium hypochlorite/amino acids and cross-linked hyaluronic acid adjunctive to non-surgical periodontal treatment: a randomized controlled clinical trial

OBJECTIVES

To compare the clinical outcomes obtained with either mechanical subgingival debridement in conjunction with a sodium hypochlorite and amino acids containing gel followed by subsequent application of a cross-linked hyaluronic acid gel (xHyA) gel, or with mechanical debridement alone.

MATERIALS AND METHODS

Fourty-eight patients diagnosed with stages II-III (Grades A/B) generalised periodontitis were randomly treated with either scaling and root planing (SRP) (control) or SRP plus adjunctive sodium hypochlorite/amino acid and xHyA gels (test). The primary outcome variable was reduction of probing depth (PD), while changes in clinical attachment level (CAL), bleeding on probing (BOP) and plaque index (PI) were secondary outcomes. The outcomes were assessed at baseline, at 3 and 6 months following therapy.

RESULTS

All patients completed the 6 months evaluation. At 6 months, the test group showed statistically significantly better results in terms of mean PD reduction (2.9 ± 0.4 vs 1.8 ± 0.6 mm, p < 0.001). Similarly, mean CAL gain was statistically higher in the test group compared to the control one (test: 2.6 ± 0.5 vs control: 1.6 ± 0.6 mm, p < 0.001). Mean BOP decreased from 81.8 ± 16.2% to 48.9 ± 14.5% in control (p < 0.001) and from 83.2 ± 15.5% to 17.6 ± 11.5% in test (p < 0.001) groups with a statistically significant difference favouring the test group (p < 0.001). Mean PI scores were reduced statistically significantly in both groups (from 38.8 ± 26% to 26.5 ± 20.5% in control (p = 0.039) and from 60.6 ± 10.9% to 12.7 ± 8.9% in test group (p < 0.001)), with a statistically significant difference between the groups (p < 0.001). The number of moderate pockets (4-6 mm) were reduced from 1518 (41.2%) to 803 (22.6%) in the control and from 1803 (48.6%) to 234 (7.7%) in the test group with a statistically significant difference between the groups (p < 0.001), while the number of deep pockets (≥ 7 mm) changed from 277 (7.6%) to 35 (1.0%) in the control and from 298 (8.7%) to 4 (0.1%) in test group (p = 0.003).

CONCLUSION

Within their limits the present data indicate that: a) both treatments resulted in statistically significant improvements in all evaluated clinical parameters, and b) the adjunctive subgingival application of sodium hypochlorite/amino acid and xHyA to SRP yielded statistically significantly higher improvements compared to SRP alone.

CLINICAL RELEVANCE

The combination of sodium hypochlorite/amino acid and xHyA gels to subgingival mechanical debridement appears to represent a valuable approach to additionally improve the outcomes of non-surgical periodontal treatment. Clinical Trial Registration Number NCT04662216 (ClinicalTrials.gov).

In vitro activity of hyaluronic acid and human serum on periodontal biofilm and periodontal ligament fibroblasts

OBJECTIVES

A beneficial effect of cross-linked hyaluronic acid (cHA) on periodontal wound healing and regeneration has recently been demonstrated. The present in vitro study was designed to obtain deeper knowledge on the effect of cHA when applied in the gingival sulcus (serum-rich environment) during non-surgical periodontal therapy.

MATERIALS AND METHODS

The influence of cHA, human serum (HS), and cHA/HS on (i) a 12-species biofilm formation, (ii) the adhesion of periodontal ligament fibroblasts (PDLF) to dentine surface, (iii) the expression and secretion of interleukin-8, and (iv) the expression of receptors of HA in PDLF and gingival fibroblasts (GF) were evaluated.

RESULTS

At 4 h of biofilm formation, cHA and HS in combination (cHA/HS) slightly decreased the colony-forming unit counts in biofilm whereas the metabolic activity of biofilm was reduced in all test groups (cHA, HS, cHA/HS) vs. control. At 24 h, the quantity of biofilm was reduced in all test groups vs. untreated control. The test substances did not affect adhesion of PDLF to dentin. HS increased the expression of IL-8 by PDLF and GF which was partially downregulated by cHA. HS and/or cHA promoted the expression of the HA receptor RHAMM in GF but not in PDLF.

CONCLUSIONS

In summary, the present data indicate that serum neither negatively affect the activity of cHA against periodontal biofilm nor had any unwanted influence on the activity of PDLF.

CLINICAL RELEVANCE

These findings lend additional support for the positive effects of cHA on cells involved in periodontal wound healing, thus pointing to its potential use in non-surgical periodontal therapy.

The Effect of Adjunctive Use of Hyaluronic Acid on Prevalence of Porphyromonas gingivalis in Subgingival Biofilm in Patients with Chronic Periodontitis: A Systematic Review

Porphyromonas gingivalis (P. gingivalis) is a Gram-negative anaerobic bacterium that plays an important role in the development and progression of periodontitis. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan that has previously demonstrated antibacterial potential in vitro against multiple bacterial species, including P. gingivalis. The purpose of this systematic review is to evaluate the effectiveness of HA as an adjunctive topical antibacterial agent to non-surgical mechanical therapy of periodontitis in reducing the prevalence of P. gingivalis in subgingival biofilms. Five clinical studies were identified that satisfied the eligibility criteria. Only three trials were suitable for the meta-analysis as they provided data at three and six months. Data on the prevalence of P. gingivalis in each study were collected. The odds ratio (OR) for measuring the effect size with a 95% confidence interval (CI) was applied to the available data. The results did not favor the use of HA during non-surgical mechanical therapy to reduce the prevalence of P. gingivalis in subgingival biofilm (odd ratio = 0.95 and 1.11 at three and six months, consecutively). Within their limitations, the current data do not indicate an advantage for using HA during mechanical periodontal therapy to reduce the prevalence of P. gingivalis.

Cross-linked hyaluronic acid gel with or without a collagen matrix in the treatment of class III furcation defects: A histologic and histomorphometric study in dogs

AIM

To histologically evaluate the effects of cross-linked hyaluronic acid (xHyA) with or without a collagen matrix (CM) on periodontal wound healing/regeneration in class III furcation defects in dogs.

MATERIALS AND METHODS

Class III furcation defects were surgically created in the mandibular premolars in six beagle dogs. The defects were randomly treated as follows: open flap debridement (OFD) + CM (CM), OFD + xHyA (xHyA), OFD + xHyA + CM (xHyA/CM) and OFD alone (OFD). At 10 weeks, the animals were euthanized for histological evaluation.

RESULTS

The newly formed bone areas in the xHyA (4.04 ± 1.51 mm² ) and xHyA/CM (4.32 ± 1.14 mm² ) groups were larger than those in the OFD (3.25 ± 0.81 mm² ) and CM (3.31 ± 2.26 mm² ) groups. The xHyA (6.25 ± 1.45 mm) and xHyA/CM (6.40 ± 1.35 mm) groups yielded statistically significantly (p < .05) greater formation of new connective tissue attachment (i.e., new cementum, with inserting connective tissue fibres) compared with the OFD (1.47 ± 0.85 mm) group. No significant differences were observed in any of the histomorphometric parameters between the xHyA and xHyA/CM groups. Complete furcation closure was not observed in any of the four treatment modalities.

CONCLUSIONS

Within their limits, the present results suggest that the use of xHyA with or without CM positively influences periodontal wound healing in surgically created, acute-type class III furcation defects.

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

The comprehensive treatment of periodontitis stage 2 to 4 aims at the resolution of periodontal inflammation and “pocket closure”, which implies a residual probing depth of ≤4 mm and a negative BoP. However, supportive periodontal therapy (SPT) regularly leaves behind persistent periodontal pockets with 5 or more mm in residual PPD and sites that often re-colonize and re-infect. Various adjunctive options for subgingival instrumentation have been proposed to enhance the antimicrobial effects to better control the re-infection of these residual sites. The locally applied adjuncts, based on their anti-inflammatory effect, are sodium hypochlorite antiseptic cleaning gel and cross-linked hyaluronic acid (xHyA). Both recently moved into the focus of clinical research on non-surgical and surgical therapy for periodontitis. The surgical use of xHyA indicates regenerative potential, supporting periodontal regeneration. This case series retrospectively analyzes the clinical benefits of the consecutive flapless application of sodium-hypochlorite-based cleaning gel and xHyA at the SPT to achieve pocket closure, thereby reducing the need for periodontal surgery. In 29 patients, 111 sites received the treatment sequence. At 6-month re-evaluation, an overall PPD reduction exceeding 2 mm was achieved, associated with a similar CAL gain (2.02 mm); the bleeding tendency (BoP) was reduced by >60%. Pocket closure occurred in almost 25% of all the sites. Within their limits, the present data suggest that the proposed combined adjunctive treatment of residual active periodontal sites yielded significant improvement in the clinical parameters. Further studies in RCT format are required to confirm these observations.

High Molecular Weight Hyaluronic Acid Reduces the Expression of Virulence Genes fimA, mfa1, hagA, rgpA, and kgp in the Oral Pathogen Porphyromonas gingivalis

Porphyromonas gingivalis (P. gingivalis) is a cornerstone pathogen in the development and progression of periodontal and peri-implant tissue destruction. It is capable of causing dysbiosis of the microbial biofilm and modulation of the host immune system. Hyaluronic acid (HA) is a naturally occurring glycosaminoglycan found in all living organisms. It is well known and has been used for improving tissue healing. In addition, some studies have suggested that there may be an antimicrobial potential to HA. The aim of this study was to evaluate the effect of hyaluronic acid, azithromycin (AZM), and chlorhexidine (CHX) on the expression of genes (i.e., fimA, mfa1, hagA, rgpA, rgpB, and kgp) related to the virulence and adhesion of P. gingivalis. The study groups were divided into four: (1) HA treated group; (2) AZM treated group; (3) CHX treated group; and (4) untreated group to serve as a negative control. P. gingivalis ATCC 33277 was cultured and then exposed to four different concentrations (100% MIC, 50% MIC, 25% MIC, and 12.5% MIC) of HA, AZM, and CHX for 24 h. The expression levels of the aforementioned genes were measured using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Relative fold-change values were calculated and compared between groups. The fold-change values of all genes combined were 0.46 ± 0.33, 0.31 ± 0.24, and 0.84 ± 0.77 for HA, AZM, and CHX, respectively. HA has downregulated all the genes by mostly a half-fold: 0.35 ± 0.20, 0.47 ± 0.35, 0.44 ± 0.25, 0.67 ± 0.46, 0.48 ± 0.33 and 0.35 ± 0.22 with fimA, mfa1, hagA, rgpA, rgpB and kgp, respectively. The effect of HA was significant on all genes except rgpB compared to the untreated control. Lower concentrations of HA tended to exhibit greater downregulation with 1 mg/mL being the most effective. High molecular weight (1.5 MDa) hyaluronic acid has a potent effect on P. gingivalis by downregulating fimA, mfa1, hagA, rgpA, and kgp. The effect of HA was generally less than that of AZM but greater than that of CHX.

Evaluation of the Hyaluronic Acid Versus the Injectable Platelet-Rich Fibrin in the Management of the Thin Gingival Phenotype: A Split-Mouth Randomized Controlled Clinical Trial

Background Several procedures have been used to enhance thin gingival phenotype and the majority of these procedures have been surgical. A new minimally invasive approach that involved multiple injections of platelet-rich fibrin (i-PRF) to enhance the thin gingival phenotype has been proposed. As the hyaluronic acid (HA) and the i-PRF share similar properties in terms of promoting periodontal regeneration, the present trial aimed to evaluate the effectiveness of multiple injections of the i-PRF in patients with thin gingival phenotypes in comparison with those of the HA in increasing the gingival thickness (GT) and the keratinized tissue width (KTW). Materials and methods Eighty-four sites from 14 systematically healthy patients who had thin gingival phenotypes (GT ≤1 mm) were included in this split-mouth randomized controlled trial. For each patient, each side of the anterior mandible was randomly allocated to one of the two materials (HA or i-PRF). In the HA group, the selected sites of the gingiva were injected with cross-linked HA using a 30-gauge microneedle. In the i-PRF group, the i-PRF was injected in the same manner. This procedure was repeated in both groups three times with intervals of 7 days. The GT, KTW, and periodontal indices: gingival index (GI), bleeding on probing (BOP), and probing depth (PD) were measured at baseline, 1 month, and 3 months following the initial injection. Results The GT increased significantly in both groups at the three assessment times (p<0.001). The KTW also showed a statistically significant increase in the intragroup comparisons in both groups (p<0.05). No statistically significant difference was observed between the two groups at the three assessment times for the GT and the KTW (p>0.05). The GI significantly decreased after 1 month and 3 months compared to the baseline values in both groups (p<0.05). The intergroup comparisons for the GI revealed no statistically significant differences at the three assessment times (p>0.05). As for the BOP and the PD, no statistically significant differences were found between the three assessment times (p>0.05) and between the two groups at each assessment time (p>0.05). Conclusion Multiple injections of the i-PRF and the HA in the thin gingival phenotype resulted in an increased GT and increased KTW, with no statistically significant differences between the two methods. Both minimally invasive techniques were more effective in improving the GT rather than the KTW.

Low-dose CBCT imaging of alveolar buccal bone adjacent to mandibular anterior teeth- a pilot study

Objectives

Accurate description of buccal bone adjacent to mandibular anterior teeth is helpful for planning and monitoring periodontal and orthodontic treatment. Low-dose cone beam computed tomography (LD-CBCT) imaging has shown promising results for very small dental structures in animals. This study asserts that LD-CBCT is sufficiently accurate to measure buccal alveolar bone adjacent to human mandibular anterior teeth.

Materials and methods

Buccal bone level adjacent to 16 mandibular anterior teeth from four human cadavers was measured radiographically using one high-dose (HD) CBCT protocol and two LD-CBCT protocols. The resulting radiographic measurements of buccal bone height (bl) and thickness (bt) were compared with reference probe and reflected-light microscopy measurements. Measurement medians and Bland–Altman plots were calculated, and a linear mixed model was used to compare raters and imaging modalities.

Results

All regression coefficients were approximately 0, indicating high interrater, intrarater, and intermodality agreement. No significant differences were found between reference measurements and CBCT protocols. The mean differences for bl measurements were 0.07 mm (rater 1 [r1]) and 0.12 mm (rater 2 [r2]) for HD-CBCT; 0.07 mm (r1) and 0.13 mm (r2) for LD-CBCT-1; and 0.02 mm (r1) and 0.01 mm (r2) for LD-CBCT-2. For bt measurements, mean differences were 0.02 mm (r1) and 0.02 mm (r2) for HD-CBCT; 0.01 mm (r1) and 0.01 mm (r2) for LD-CBCT-1; and 0.00 mm (r1) and 0.01 mm (r2) for LD-CBCT-2.

Conclusions

Within the limitations of the present study, LD-CBCT seems to be a precise method for describing buccal bone and its thickness adjacent to mandibular anterior teeth in this experimental setting.

Clinical relevance

For the first time, this study showed LD-CBCT produces excellent results and is a reliable modality for imaging buccal bone in vitro. If clinical studies confirm these results, LD-CBCT could enable better treatment planning and monitoring at a radiation dose that is far lower than that of conventional HD-CBCT but similar to that of panoramic views.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04389-x.

Coronally advanced flap with and without hyaluronic acid (HYALOSS) for the treatment of gingival recession – a randomized clinical trial

Objectives: To compare and evaluate the surgical outcome of gingival recession treatment using CAF alone or in conjunction with hyaluronic acid (HA) on Miller's Class I and class II gingival recession defects. Materials and methods: After randomisation, the control group (15 patients) received CAF alone and the test group (15 patients) received HA as an adjunct to CAF technique for an isolated gingival recession accompanied by an adequate width of keratinized gingiva on maxillary canines and premolars. All patients were evaluated at 7, 15, 30, 60 and 90 days interval post-operatively. Data obtained was subjected to statistical analysis and p value <0.05 was considered as statistically significant. Results: At 90 days interval statistically highly significant root coverage was obtained with mean gain of 66.1% in control group and 86.6% in test group. Statistically significant reduction in depth of gingival recession and gain in clinical attachment level was found for control and the test groups, and intergroup comparison showed statistically significant differences for root coverage and clinical attachment level between the groups (p = 0.000), however no significant differences were found for width of attached gingiva, keratinized gingiva and gingival thickness between the groups at 90 days (p > 005). Conclusion: HA has proven to be beneficial in the field of regenerative therapy. Our analysis suggested that HA can be used as a promising adjunct with CAF for root coverage, however further studies are required to imply the results on larger population.

A randomized controlled trial evaluating hyaluronic acid gel as wound healing agent in alveolar ridge preservation

AIM

To compare the results of administration of hyaluronic acid (HA) gel to no gel administration following alveolar ridge preservation (ARP) in terms of changes in wound dimensions over time.

MATERIALS AND METHODS

Systemically healthy patients scheduled for ARP at one or two sites in the incisor, cuspid, or premolar area with at least one neighbouring tooth and >50% buccal bone present following extraction were included. ARP consisted of socket grafting with collagen-enriched, deproteinized bovine bone mineral and socket sealing by means of a collagen matrix. Following surgical therapy, sites were randomly allocated to the control group (no gel application) or the test group (0.8% HA gel applied onto the collagen matrix three times per day for 7 days). Bucco-lingual and mesio-distal wound dimensions were registered at T0 (immediately post operation), T1 (1 week), and T2 (3 weeks). Patient-reported outcomes, clinical outcomes, and hard and soft tissue changes were recorded up to 4 months (T3).

RESULTS

In the control group, 20 patients (7 males, 13 females; mean age 53.30) with 23 sites, and in the test group 18 patients (9 males, 9 females; mean age 52.56) with 23 sites, were included. There were no significant differences between the groups in the changes in wound dimensions from T0 to T2 (bucco-lingual aspect: p = .340; mesio-distal aspect: p = .883). Three sites (13%) in the control group and six (26%) in the test group demonstrated complete wound resolution at T2 (p = .259). HA failed to show any effect on the number of analgesics taken (p = .175), patient-reported outcomes (p ≥ .263), alveolitis (p = .136), socket healing (p ≥ .424), soft tissue changes (p ≥ .064), or mucosal scarring (p = .548). However, significantly more horizontal bone loss at the coronal aspect was found in the test group (p ≤ .025).

CONCLUSION

HA failed to promote wound resolution on a collagen matrix. This study was registered in ClinicalTrials.gov (NCT04467736).

Soft Tissue Regeneration at Natural Teeth

This article provides an overview of the best-documented surgical techniques for recession coverage and draws conclusions for the clinician. Use of a connective tissue graft with either coronally advanced flap (CAF) or tunnel is the most predictable technique for the treatment of single and multiple gingival recessions. Long-term results exist only for CAF with/without connective tissue graft providing evidence for long-term stability with only minor relapses. Soft tissue replacement materials and biologics may represent a valuable modality to additionally improve the clinical outcomes obtained with CAF alone or, in certain clinical situations, to serve as an alternative to autogenous tissue.

Treatment of Intrabony Defects with a Combination of Hyaluronic Acid and Deproteinized Porcine Bone Mineral

Background: this study evaluates the clinical outcomes of a novel approach in treating deep intrabony defects utilizing papilla preservation techniques with a combination of hyaluronic acid (HA) and deproteinized porcine bone mineral. Methods: 23 patients with 27 intrabony defects were treated with a combination of HA and deproteinized porcine bone mineral. Clinical attachment level (CAL), pocket probing depth (PPD), gingival recession (REC) were recorded at baseline and 6 months after the surgery. Results: At 6 months, there was a significant CAL gain of 3.65 ± 1.67 mm (p < 0.001) with a PPD reduction of 4.54 ± 1.65 mm (p < 0.001), which was associated with an increase in gingival recession (0.89 ± 0.59 mm, p < 0.001). The percentage of pocket resolution based on a PPD ≤4 mm was 92.6% and the failure rate based on a PPD of 5 mm was 7.4%. Conclusions: the present findings indicate that applying a combined HA and xenograft approach in deep intrabony defects provides clinically relevant CAL gains and PPD reductions compared to baseline values and is a valid new approach in treating intrabony defects.

Histological Evaluation of Gingival and Intrabony Periodontal Defects Treated with Platelet-rich Fibrin Using Different Protocols: A Canine Study

PURPOSE

To histologically compare the effects of platelet-rich fibrin (PRF) produced using different protocols on periodontal wound healing/regeneration in periodontal defects in dogs.

MATERIALS AND METHODS

Dehiscence-type gingival recession and two-wall intrabony defects were created bilaterally in the maxillary canines and mandibular premolars, respectively, in four beagle dogs. The recession defects were randomly treated with coronally advanced flap (CAF) alone, CAF and PRF produced via fixed-angle centrifugation (F-PRF; Leukocyte and PRF (L-PRF) protocol) or CAF and PRF produced via horizontal centrifugation (H-PRF). After 2 weeks, the two-wall intrabony defects were randomly treated as follows: open flap debridement (OFD), OFD + F-PRF, OFD + H-PRF and OFD + heated albumin with PRF using bio-heat technologies (Alb-PRF). Eight weeks after the 2nd reconstructive surgery, the animals were euthanised for histological evaluation.

RESULTS

In the PRF-applied defects, new bone and new cementum formation occurred to varying degrees regardless of the protocols used to produce PRF. Particularly in the two-wall intrabony defects, new bone formation extended from the host bone toward the coronal region of the defects in the H-PRF applied sites compared with those in the OFD, F-PRF and Alb-PRF groups, and the H-PRF group showed the greatest amount of newly formed cementum.

CONCLUSION

PRF induced periodontal regeneration in gingival recession and two-wall intrabony defects in dogs. Further studies are needed to determine the optimal protocol for obtaining predictable periodontal regeneration in periodontal defects in humans.

Cross-linked hyaluronic acid slows down collagen membrane resorption in diabetic rats through reducing the number of macrophages

OBJECTIVES

We previously showed that accelerated degradation of collagen membranes (CMs) in diabetic rats is associated with increased infiltration of macrophages and blood vessels. Since pre-implantation immersion of CMs in cross-linked high molecular weight hyaluronic acid (CLHA) delays membrane degradation, we evaluated here its effect on the number of macrophages and endothelial cells (ECs) within the CM as a possible mechanism for inhibition of CM resorption.

MATERIALS AND METHODS

Diabetes was induced with streptozotocin in 16 rats, while 16 healthy rats served as control. CM discs were labeled with biotin, soaked in CLHA or PBS, and implanted under the scalp. Fourteen days later, CMs were embedded in paraffin and the number of macrophages and ECs within the CMs was determined using antibodies against CD68 and transglutaminase II, respectively.

RESULTS

Diabetes increased the number of macrophages and ECs within the CMs (∼2.5-fold and fourfold, respectively). Immersion of CMs in CLHA statistically significantly reduced the number of macrophages (p < 0.0001) in diabetic rats, but not that of ECs. In the healthy group, CLHA had no significant effect on the number of either cells. Higher residual collagen area and membrane thickness in CLHA-treated CMs in diabetic animals were significantly correlated with reduced number of macrophages but not ECs.

CONCLUSIONS

Immersion of CM in CLHA inhibits macrophage infiltration and reduces CM degradation in diabetic animals.

CLINICAL RELEVANCE

The combination of CLHA and CM may represent a valuable approach when guided tissue regeneration or guided bone regeneration procedures are performed in diabetic patients.