Hyaluronic acid as adjunctive to non-surgical and surgical periodontal therapy: a systematic review and meta-analysis

Early periodontal wound healing after chlorhexidine rinsing: a randomized clinical trial

OBJECTIVES

This single-center randomized, parallel design, clinical trial with a 2-week follow-up involved patients affected by periodontitis undergoing periodontal surgery. The aim was to evaluate periodontal surgical wound healing with the use of chlorhexidine-based mouth rinses versus an untreated control group.

MATERIALS AND METHODS

Periodontal surgery was performed following a standardized protocol. Patients were randomly prescribed i) chlorhexidine (CHX) + anti-discoloration system (ADS) + hyaluronic acid (HA), ii) CHX + ADS or iii) no treatment (control group). Plaque score, gingival inflammation, and Early Healing Index (EHI), assessing the degree of wound closure and the presence of fibrin and necrosis, were evaluated at 3, 7 and 14 days after surgery.

RESULTS

In total, 33 patients were enrolled. Patients were comparable at baseline for all measured clinical parameters. At 3-days wound healing was significantly improved in all patients treated with CHX + ADS-based mouth rinses with a lower EHI score at the interdental papillae compared with control group (p < 0.01). CHX + ADS + HA group presented improved healing across all time points in terms of EHI, plaque containment, and gingival inflammation when compared to control group (p < 0.01).

CONCLUSIONS

The usage of CHX-ADS following periodontal surgery improved early wound healing, reduced plaque accumulation and gingival inflammation. During the early post-operative period the adjunct of HA further improved soft tissue closure.

CLINICAL RELEVANCE

This study aims at evaluating the response of gingival tissues to mouth rinsing with chlorhexidine and anti-discoloration system (CHX + ADS) or CHX + ADS + hyaluronic acid (CHX + ADS + HA) versus no rinse in terms of healing of the periodontal surgical wound. CHX + ADS mouth rinses enhanced early soft tissue closure after periodontal surgery and contributed to the reduction in plaque accumulation and gingival inflammation. The adjunct of HA may be beneficial especially in the early post-operative period. CHX + ADS administration following periodontal surgery may improve soft tissue healing in the first two post-operative weeks.

Adjunctive use of hyaluronic acid in the treatment of gingival recessions: a systematic review and meta-analysis

OBJECTIVES

To explore the efficacy of Hyaluronic acid as an adjunctive in treatment of gingival recessions (GR).

MATERIALS AND METHODS

A systematic literature search was performed in several electronic databases, including Medline/ PubMed, Embase, CENTRAL and LILACS. Recession improvement was evaluated through multiple outcome variables. The Cochrane Risk of Bias tool and the ROBINS-I tool were used to assess the quality of the included trials. Weighted Mean Differences (WMDs) and 95% confidence intervals (CIs) between test and control sites were estimated through meta-analysis using a random-effect model for the amount of Relative Root Coverage (RRC).

RESULTS

A total of 3 randomised studies were deemed as eligible for inclusion. Their data were also used for pooling the effect estimates. Overall analysis of RRC (3 studies) presented a WMD of 7.49% (p = 0.42; 95% CIs -10.88, 25.86) in favour of adjunctive use of hyaluronic acid during Coronally Advanced Flap (CAF) technique, although statistical significance was not reached. Statistical heterogeneity was found to be high (I2 = 80%).

CONCLUSIONS

Within their limitations, the present data indicate that the local application of Hyaluronic acid does not lead to additional clinical benefits when used as an adjunctive to the treatment of GR with CAF. However, due to the high heterogeneity among the studies, additional well-designed RCTs are needed to provide further evidence on this clinical indication for the use of Hyaluronic acid.

CLINICAL RELEVANCE

In the frame of the current review, the adjunctive use of Hyaluronic acid does not additionally improve the clinical outcomes obtained during treatment of GR with CAF.

Healing of Periodontal Suprabony Defects following Treatment with Open Flap Debridement with or without Hyaluronic Acid (HA) Application

Background and Objectives: This randomized, double-arm, multicentric clinical trial aims to compare the clinical outcomes following the treatment of suprabony periodontal defects using open flap debridement (OFD) with or without the application of hyaluronic acid (HA). Materials and Methods: Sixty systemically healthy patients with at least two teeth presenting suprabony periodontal defects were randomly assigned with a 1:1 allocation ratio using computer-generated tables into a test (OFD + HA) or control group (OFD). The main outcome variable was clinical attachment level (CAL). The secondary outcome variables were changes in mean probing pocket depth (PPD), gingival recession (GR), full-mouth plaque score (FMPS), and full-mouth bleeding score (FMBS). All clinical measurements were carried out at baseline and 12 months. Results: Sixty patients, thirty in each group, were available for statistical analysis. The mean CAL gain was statistically significantly different (p < 0.001) in the test group compared with the control group (3.06 ± 1.13 mm vs. 1.44 ± 1.07 mm). PPD reduction of test group measurements (3.28 ± 1.14 mm) versus the control group measurements (2.61 ± 1.22 mm) were statistically significant (p = 0.032). GR changes were statistically significant only in the test group 0.74 ± 1.03 mm (p < 0.001). FMBS and FMPS revealed a statistically significant improvement mostly in the test group. Conclusions: Suprabony periodontal defects could benefit from the additional application of HA in conjunction with OFD in terms of improvement of the clinical parameters compared with OFD alone.

From Basic Science to Clinical Practice: A Review of Current Periodontal/Mucogingival Regenerative Biomaterials

Periodontitis is a dysbiosis-driven inflammatory disease affecting the tooth-supporting tissues, characterized by their progressive resorption, which can ultimately lead to tooth loss. A step-wise therapeutic approach is employed for periodontitis. After an initial behavioral and non-surgical phase, intra-bony or furcation defects may be amenable to regenerative procedures. This review discusses the regenerative technologies employed for periodontal regeneration, highlighting the current limitations and future research areas. The search, performed on the MEDLINE database, has identified the available biomaterials, including biologicals (autologous platelet concentrates, hydrogels), bone grafts (pure or putty), and membranes. Biologicals and bone grafts have been critically analyzed in terms of composition, mechanism of action, and clinical applications. Although a certain degree of periodontal regeneration is predictable in intra-bony and class II furcation defects, complete defect closure is hardly achieved. Moreover, treating class III furcation defects remains challenging. The key properties required for functional regeneration are discussed, and none of the commercially available biomaterials possess all the ideal characteristics. Therefore, research is needed to promote the advancement of more effective and targeted regenerative therapies for periodontitis. Lastly, improving the design and reporting of clinical studies is suggested by strictly adhering to the Consolidated Standards of Reporting Trials (CONSORT) 2010 statement.

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.

Topical Agents in Biofilm Disaggregation: A Systematic Review and Meta-Analysis

Background: to evaluate the effectiveness of different topical agents in biofilm disaggregation during non-surgical periodontal therapy. Methods: the search strategy was conducted according to the PRISMA 2020 on Pubmed, Cochrane Library, Scopus, and Web of Science, and it was registered in PROSPERO, ID: CRD42023474232. It included studies comparing non-surgical periodontal therapy (NSPT) with and without the application of topical agents for biofilm disruption. A risk of bias analysis, a qualitative analysis, and a quantitative analysis were performed. Results: out of 1583 records, 11 articles were included: 10 randomized clinical trials and one retrospective analysis. The total number of participants considered in the 11 articles included in the study was 386. The primary outcomes were probing pocket depth (PPD), clinical attachment level (CAL), and bleeding indices. The secondary outcomes were plaque indices, gingival recessions, and microbiological parameters. The meta-analysis revealed the following: [Weighted mean difference (WMD): -0.37; 95% confidence interval (CI) (-0.62, -0.12), heterogeneity I2: 79%, statistical significance p = 0.004]. Conclusions: the meta-analysis of probing pocket depth reduction (PPD) between baseline and follow-up at 3-6 months showed a statistically significant result in favor of sulfonated phenolics gel. The scientific evidence is still limited and heterogeneous; further randomized clinical trials are required.

Green tea and hyaluronic acid gel enhance fibroblast activation and improves the gingival healing post-third molar extraction

This study evaluates the effects of a green tea (Camellia sinensis) and hyaluronic acid gel on fibroblast activity and alveolar bone repair following third molar extractions. By examining the gene expression related to cell survival, proliferation, and angiogenesis, the study bridges in vitro findings with clinical outcomes in a split-mouth randomized trial. Human fibroblasts were exposed to the treatment gel, analysing gene expression through RT-qPCR. Twenty participants undergoing bilateral third molar extractions received the test gel on one side and a placebo on the other. Assessments included patient-reported outcomes, professional evaluations, and radiographic analyses at multiple postoperative intervals. The test gel significantly enhanced AKT, CDKs, and VEGF gene expressions, indicating a positive effect on angiogenesis and cell proliferation. Clinically, it resulted in reduced exudate, swelling, and secondary interventions, with radiographs showing improved alveolar bone density after 90 days. The green tea and hyaluronic acid gel significantly improves soft tissue and bone healing post-extraction, offering a promising adjunctive therapy for enhancing postoperative recovery. This gel represents a novel adjuvant treatment option for facilitating improved healing outcomes after third molar extractions, highlighting its potential utility in clinical dental practice.

Effect of sodium hypochlorite gel on bacteria associated with periodontal disease

OBJECTIVES

An adjunct in non-surgical periodontal therapy might be sodium hypochlorite (NaOCl)-based agents. The purpose of the present in vitro study was to get deeper knowledge on the influence of different parameters as time after mixing, pH, and chemical composition of an amino acid 0.475% NaOCl (AA-NaOCl) gel consisting of two components on its anti-biofilm activity.

MATERIALS AND METHODS

Six-species biofilms were cultured for 5 days, before AA-NaOCl gel was applied. In the different series, the influence of the time after mixing of the two components before application, of the concentration of NaOCl in the gel mixture, of the pH of the gel mixture, and of an exchange of the amino acid component by hyaluronic acid (HA), was analyzed.

RESULTS

Mixing time point experiments showed that the AA-NaOCl gel is capable of statistically significantly reducing colony-forming unit (cfu) counts up to 30 min after mixing, but only up to 20 min after mixing the reduction was more than 2 log10 cfu. The pH experiments indicate that a reduced pH results in a reduced activity of the NaOCl formulation. NaOCl concentrations in the formulation in the range from 0.475 to 0.2% provide adequate activity on biofilms. A HA/NaOCl gel was equally active against the biofilm as the AA-NaOCl gel.

CONCLUSION

Mixing of the components should be made in a timeframe of 20 min before applications. An optimization of the composition of the NaOCl formulation might be possible and should be a topic in further in vitro studies.

CLINICAL RELEVANCE

The AA-NaOCl gel formulation can be mixed up to 20 min before application. Further, the study indicates that the composition of the NaOCl gel formulation can be optimized.

Repeated local delivery of hyaluronic acid gel as adjunctive treatment of residual pockets in periodontitis patients undergoing supportive periodontal care. A randomized controlled clinical trial

OBJECTIVES

To assess the effect of hyaluronic acid (HyA) application as adjunct to re-instrumentation of residual pockets in patients undergoing regular supportive periodontal care (SPC).

METHODS

Chronic periodontitis patients (stage III and IV, grade B and C) with 4 interproximal residual pockets were randomly assigned to the test (HyA gel) or control (saline) group. After subgingival instrumentation, test or control substance was applied subgingivally, then daily supragingivally for 3 months, and if required a second time after subgingival re-instrumentation after 3 months. Clinical and patient reported outcome parameters were recorded every 3 months for 12 months. Pocket closure [probing pocket depth (PPD) ≤ 4mm with absence of bleeding on probing (BoP) at PPD = 4mm] was the main outcome parameter.

RESULTS

Fifty-six patients (221 experimental sites) were analysed. Pocket closure was achieved in 56.8 and 46.6% of the experimental sites in the test and control group, respectively (p > 0.05), while median PPD and PPD distribution (< 5mm/5mm/ > 5mm) differed significantly between groups in favour of the test group, at 12 months. Further, significantly fewer sites in the HyA group required re-instrumentation at 3 months, and sites in the HyA group showed a tendency for lower odds to remain diseased compared to the control group (OR 0.48, 95%CI 0.22-1.06). The odds for a site to remain diseased after 12 months increased significantly in the presence of plaque (OR 7.94, 95%CI 4.12-15.28), but in general, decreased significantly over time (OR 0.48, 95%CI 0.28-0.81).

CONCLUSION

Re-instrumentation of residual pockets in SPC patients, per se, leads to a significant increase in pocket closure over time; this was impeded by poor plaque control. Repeated local application of HyA results in fewer sites requiring re-instrumentation and might slightly improve the rate of pocket closure. (clinicaltrials.gov registration nr. NCT04792541).

CLINICAL RELEVANCE

HyA gel is easy to apply, well accepted by patients, and may have some positive effect in terms of fewer sites requiring re-instrumentation at 3 months and higher pocket closure rate at 12 months.

Control of tissue homeostasis by the extracellular matrix: Synthetic heparan sulfate as a promising therapeutic for periodontal health and bone regeneration

Proteoglycans are core proteins associated with carbohydrate/sugar moieties that are highly variable in disaccharide composition, which dictates their function. These carbohydrates are named glycosaminoglycans, and they can be attached to proteoglycans or found free in tissues or on cell surfaces. Glycosaminoglycans such as hyaluronan, chondroitin sulfate, dermatan sulfate, keratan sulfate, and heparin/heparan sulfate have multiple functions including involvement in inflammation, immunity and connective tissue structure, and integrity. Heparan sulfate is a highly sulfated polysaccharide that is abundant in the periodontium including alveolar bone. Recent evidence supports the contention that heparan sulfate is an important player in modulating interactions between damage associated molecular patterns and inflammatory receptors expressed by various cell types. The structure of heparan sulfate is reported to dictate its function, thus, the utilization of a homogenous and structurally defined heparan sulfate polysaccharide for modulation of cell function offers therapeutic potential. Recently, a chemoenzymatic approach was developed to allow production of many structurally defined heparan sulfate carbohydrates. These oligosaccharides have been studied in various pathological inflammatory conditions to better understand their function and their potential application in promoting tissue homeostasis. We have observed that specific size and sulfation patterns can modulate inflammation and promote tissue maintenance including an anabolic effect in alveolar bone. Thus, new evidence provides a strong impetus to explore heparan sulfate as a potential novel therapeutic agent to treat periodontitis, support alveolar bone maintenance, and promote bone 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.

Effects of topically administered 0.6% hyaluronic acid on the healing of labial frenectomy in conventional and 940-nm indium gallium arsenide phosphide (InGaAsP) diode laser techniques in pediatric patients: a randomized, placebo-controlled clinical study

This study aimed to investigate the effects of 0.6% hyaluronic acid (HA) gel on the healing process and postoperative pain levels after diode laser-assisted labial frenectomy in pediatric patients. Ninety-six pediatric patients (females, 50 and males, 46) aged 8-14 years were randomly divided into four groups as follows: (1) conventional frenectomy with 0.6% topically administered HA (CFH, n = 24); (2) conventional frenectomy with placebo gel (CFP, n = 24); (3) frenectomy performed by diode laser with 0.6% topically administered HA (DLH, n = 24); and (4) frenectomy performed by diode laser with placebo gel (DLP, n = 24). HA application was continued for 1 week thrice daily after the frenectomy. Visual analog scale forms were collected from patients 1 week after the operation. In addition, the plaque index, gingival index, periodontal probing depth, and keratinized tissue width and thickness were recorded. This process was repeated 1 and 3 months after the first visit. The DLH group revealed significant differences in the probing depth, bleeding on probing, keratinized gingiva width, and attached gingiva width according to dual comparisons of the initial, first, and third-month values (p = 0.010, p = 0.007, p<0.001, and p = 0.001, respectively). Significant differences were observed between the CFP and CFH groups according to the initial and initial third-month values with regard to the bleeding on probing (p=0.019 and p = 0.019, respectively). The attached gingival thickness revealed significant differences between the CFP and CFH groups for the initial and initial-third-month comparisons (p = 0.005 and p = 0.007, respectively). The mean values of the initial and initial-third-month differences were significantly higher in the CFH group than those in the CFP group. HA- and laser-assisted labial frenectomies revealed better outcomes in terms of the probing depth, attached gingiva width, keratinized gingiva width, healing process, and postoperative comfort.

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.

Osteogenic stimulation of osteoprogenitors by putamen ovi peptides and hyaluronic acid

Eggshell peptides (EP) majorly contribute to rapid bone building in chicks, wherefore this paper investigated their potential for stimulating osteogenesis in vitro. In this study, the effects of EP, also called putamen ovi peptides and a combination of hyaluronic acid with EP in cell culture medium were tested towards proliferation, differentiation, gene expression and mineralization of bovine osteoprogenitors and primary human osteoblasts. The influence of EP at concentrations of 0.005 g/L, 0.5 g/L and 0.5 g/L with 0.25% hyaluronic acid was analyzed using immunocytochemical staining of bone-specific matrix proteins, namely collagen type I, osteonectin, osteopontin and osteocalcin, to prove osteoblastic differentiation. Additionally, Richardson-staining was performed. All tests revealed a superior osteoblastic differentiation with EP at 0.5 g/L after 5 days of cultivation. Hyaluronic acid alone showed controversial results and partially constrained osteoblastic differentiation in combination with EP to a level as low as for pure EP at 0.005 g/L. Of particular interest is the osteoblast-typical mineralization, as an important indicator of bone formation, which was measured indirectly via the calcium concentration after cultivation over 4 weeks. The mineralization showed an increase by a factor of 286 during the cultivation of primary human osteoblasts with hyaluronic acid and EP. Meanwhile, cell cultures treated with EP (0.5 g/L) only showed an 80-fold increase in calcium concentration.The influence of EP (0.5 g/L) on primary human osteoblasts was investigated by gene expression after 2 weeks of cultivation. Microarray and qRT-PCR analysis showed a strongly increased expression of main important genes in bone formation, bone regeneration and the physiological bone remodelling processes. Namely, BMP 2, osteopontin and the matrix metalloproteinases 1 and 9, were present during in vitro osteoprogenitor culture with EP. By explicitly underlining the potential of eggshell peptides for stimulating osteogenesis, as well as emphasizing complex and controversial interaction with hyaluronan, this manuscript is relevant for developing new functionalized biomaterials for bone regeneration.

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.

Reconstructive Peri-Implantitis Therapy by Using Bovine Bone Substitute with or without Hyaluronic Acid: A Randomized Clinical Controlled Pilot Study

BACKGROUND

The present pilot study aimed to assess clinical and radiographic efficiencies of bovine bone substitute (BBS) merged with hyaluronic acid (HA) in peri-implantits reconstructive surgery.

METHODS

Peri-implantitis (diagnosed 6.03 ± 1.61 years of implant loading) bone defects were randomly treated either with BBS plus HA (test group) or BBS alone (control group). Clinical parameters including peri-implant probing depth (PPD), bleeding on probing (BOP), implant stability (ISQ), and radiographic changes in vertical and horizontal marginal bone (MB) levels were assessed at six months postoperatively. New temporary and permanent screw-retained crowns were made at two weeks and three months postoperatively. Data were analyzed using parametric and non-parametric tests.

RESULTS

In both groups, 75% of patients and 83% of implants achieved treatment success after six months (no BOP, PPD <5 mm, and no further MB loss). Clinical outcomes improved over time within groups; however, without significant difference between them. ISQ value obtained significant increases in the test compared to the control group at six months postoperatively (p < 0.05). The vertical MB gain was significantly greater in the test group compared to the control (p < 0.05).

CONCLUSIONS

Short-term outcomes suggested that BBS merged with HA could improve clinical and radiographic outcomes in peri-implantitis reconstructive therapy.

3D-Printed Soft Membrane for Periodontal Guided Tissue Regeneration

OBJECTIVES

The current study aimed to perform an in vivo examination using a critical-size periodontal canine model to investigate the capability of a 3D-printed soft membrane for guided tissue regeneration (GTR). This membrane is made of a specific composition of gelatin, elastin, and sodium hyaluronate that was fine-tuned and fully characterized in vitro in our previous study. The value of this composition is its potential to be employed as a suitable replacement for collagen, which is the main component of conventional GTR membranes, to overcome the cost issue with collagen.

METHODS

Critical-size dehiscence defects were surgically created on the buccal surface of the roots of canine bilateral mandibular teeth. GTR treatment was performed with the 3D-printed membrane and two commercially available collagen membranes (Botiss Jason® and Smartbrane-Regedent membranes) and a group without any membrane placement was considered as the control group. The defects were submerged with tension-free closure of the gingival flaps. Histologic and histometric analyses were employed to assess the periodontal healing over an 8-week experimental period.

RESULTS

Histometric evaluations confirmed higher levels of new bone formation in the 3D-printed membrane group. Moreover, in all defects treated with the membranes, the formation of periodontal tissues, bone, periodontal ligaments, and cementum was observed after 8 weeks, while in the control group, only connective tissue was found in the defect sites. There was no clinical sign of inflammation or recession of gingiva in any of the groups.

SIGNIFICANCE

The 3D-printed gelatin/elastin/sodium hyaluronate membrane can be safe and effective for use in GTR for periodontal tissue regeneration therapies, with better or comparable results to the commercial collagen membranes.

Immunomodulatory fibrous hyaluronic acid-Fmoc-diphenylalanine-based hydrogel induces bone regeneration

AIM

To investigate the potential of an ultrashort aromatic peptide hydrogelator integrated with hyaluronic acid (HA) to serve as a scaffold for bone regeneration.

MATERIALS AND METHODS

Fluorenylmethyloxycarbonyl-diphenylalanine (FmocFF)/HA hydrogel was prepared and characterized using microscopy and rheology. Osteogenic differentiation of MC3T3-E1 preosteoblasts was investigated using Alizarin red, alkaline phosphatase and calcium deposition assays. In vivo, 5-mm-diameter calvarial critical-sized defects were prepared in 20 Sprague-Dawley rats and filled with either FmocFF/HA hydrogel, deproteinized bovine bone mineral, FmocFF/Alginate hydrogel or left unfilled. Eight weeks after implantation, histology and micro-computed tomography analyses were performed. Immunohistochemistry was performed in six rats to assess the hydrogel's immunomodulatory effect.

RESULTS

A nanofibrous FmocFF/HA hydrogel with a high storage modulus of 46 KPa was prepared. It supported osteogenic differentiation of MC3T3-E1 preosteoblasts and facilitated calcium deposition. In vivo, the hydrogel implantation resulted in approximately 93% bone restoration. It induced bone deposition not only around the margins, but also generated bony islets along the defect. Elongated M2 macrophages lining at the periosteum-hydrogel interface were observed 1 week after implantation. After 3 weeks, these macrophages were dispersed through the regenerating tissue surrounding the newly formed bone.

CONCLUSIONS

FmocFF/HA hydrogel can serve as a cell-free, biomimetic, immunomodulatory scaffold for bone regeneration.

Clinical efficacy of hyaluronic acid in the treatment of periodontal intrabony defect: a systematic review and meta-analysis

OBJECTIVE

This systematic review aimed to evaluate the effects of hyaluronic acid (HA) alone or in combination with any bone substitute for the treatment of intrabony defects (IBDs).

MATERIAL AND METHODS

Six databases were searched up to April 2022 to find randomized clinical trials comparing the clinical effects of open flap debridement (OFD) + HA versus OFD alone (first group) or OFD + HA + bone substitutes versus OFD + bone substitutes (second group) in the treatment of IBDs with a follow-up of at least 3 months. Random effects models of mean differences were used to determine the clinical attachment level (CAL) gain, probing depth (PD) reduction, and radiographic bone fill (RBF).

RESULTS

Of the 276 studies identified, 6 were included in the qualitative synthesis, and 5 in the meta-analyses. The meta-analyses in the first group showed a statistically significant differences for CAL gain (mean difference [MD]:1.00; 95% confidence interval [CI]:0.65 - 1.35; n = 2) and PD reduction (MD: 0.76; 95%CI: 0.34 - 1.17; n = 2) favoring HA + OFD at 6 months. However, in the second group, the meta-analyses did no show additional effect of HA in association with bone substitute was demonstrated for either CAL gain (MD: 0.57; 95%CI: - 0.30 - 1.43; n = 2) or PD reduction (MD: 1.05; 95%CI: - 0.38 - 2.47; n = 2) but did show significant differences for RBF (MD: 0.57; 95%CI: 0.15 - 0.99; n = 2) at 12 months.

CONCLUSION

Compared with OFD alone, local application of HA in the treatment of IBDs provided a significant CAL gain and PD reduction at 6 months. However, its combination with bone substitutes showed no statistically significant differences at 12 months.

CLINICAL RELEVANCE

The use of OFD + HA improves the CAL and PD in the treatment of IBDs compared to OFD only after 6 months of follow-up. These results are not maintained after 12 months.

Drug Release and Cytotoxicity of Hyaluronic Acid and Zinc Oxide Gels, An In-Vitro Study

Hyaluronic acid (HA) is a naturally occurring biopolymer, with a remarkable wound healing property. Zinc-oxide non-eugenol is a material widely used for periodontal dressing in dentistry. However, it has been reported that zinc oxide non-eugenol is toxic to osteoblasts and fibroblasts. Hence, the present study aimed to evaluate the drug release and cytotoxicity of HA and zinc-oxide gels. Hydrogels of HA and zinc oxide were formulated with carbopol as a carrier. In vitro drug release was performed by UV spectrophotometry, dialysis, and vial bag methods. Cytotoxicity assessment of HA and zinc-oxide gels was performed in human periodontal ligament fibroblasts (HPdLF) and human gingival fibroblasts (hGFs). An inverted phase-contrast microscope was used to assess the morphological changes. At 24 and 48 hr, HPdLF cells showed the highest viability in 0.1% low molecular weight-HA (LMW-HA) with a median value of 131.9, and hGFs showed the highest viability in 5% LMW-HA with a median of 129.56. The highest viability of HPdLF cells was observed in 5% high molecular weight-HA (HMW-HA), with a median value of 127.11. hGFs showed the highest viability in 1% HMW-HA with a median value of 97.99. Within the limitations of the present study, we concluded that LMW-HA is more efficient than HMW-HA. Both HPdLF and hGF cells showed complete cell morbidity with zinc-oxide hydrogels. Therefore, zinc oxide-based gels in concentrations as low as 9% could be toxic intraorally to soft tissues that harbor gingival and periodontal ligament fibroblasts.

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.

Efficiency of Hyaluronic Acid in Infrabony Defects: A Systematic Review of Human Clinical Trials

Background and objectives: The aim of this systematic review was to assess the electronic literature about the benefits of using hyaluronic acid (HA) in the surgical periodontal treatment of infrabony defects. Materials and methods: This review was conducted under the PRISMA guidelines. The electronic search was conducted on PubMed, Scopus, Web of Science, and Cochrane databases until February 2022. The inclusion criteria consisted of human clinical trials that reported the use of HA in open-flap debridement (OFD) for infrabony defects. The assessment of risk of bias was performed using the Cochrane risk of bias tool. Statistical analysis was performed using Review Manager. Results: Overall, three RCTs were found eligible for the statistical analysis. Probing depth (PD) reduction and clinical attachment level (CAL) gain in the HA test group presented WMs of −1.11 mm (95% CI −2.38 to 0.16 mm; p = 0.09) and −1.38 mm (95% CI −2.26 to −0.49 mm; p = 0.002), respectively. However, the heterogeneity of the RCTs was high, and the risk of bias, in general, was low. Conclusions: The use of hyaluronic acid seems to have beneficial effects in periodontal surgery using OFD, in terms of PD and CAL. To draw a clear conclusion, more adapted and well-designed clinical trials are needed to assess the advantage of this product in comparison with other products.

Enamel matrix derivative as adjunctive to non-surgical periodontal therapy: a systematic review and meta-analysis of randomized controlled trials

Objectives

To assess the potential additional benefit of the local application of enamel matrix derivative (EMD) on the clinical outcomes following non-surgical periodontal therapy (NSPT) (steps 1 and 2 periodontal therapy).

Materials and Methods

A systematic literature search was performed in several electronic databases, including Medline/PubMed, Embase, The Cochrane Register of Central Trials (CENTRAL), LILACS, and grey literature. Only randomized controlled clinical trials (RCTs) were eligible for inclusion. Clinical attachment level (CAL) change (primary outcome), probing pocket depth (PPD), and bleeding on probing (BoP) reductions (secondary outcomes) were evaluated. The Cochrane Risk of Bias tool (RoB 2.0) was used to assess the quality of the included trials. Weighted mean differences (WMDs) and 95% confidence intervals (CIs) between test and control sites were estimated using a random-effect model for amount of mean CAL and PPD change.

Results

Six RCTs were included for the qualitative analysis, while data from 4 studies were used for meta-analysis. Overall analysis of CAL gain (3 studies) and PPD reduction (4 studies) presented WMD of 0.14 mm (p = 0.74; CI 95% − 0.66; 0.94) and 0.46 mm (p = 0.25; CI 95% − 0.33; 1.26) in favor of NSPT + EMD compared to NSPT alone respectively. Statistical heterogeneity was found to be high in both cases (I² = 79% and 87%, respectively).

Conclusions

Within their limitations, the present data indicate that the local application of EMD does not lead to additional clinical benefits after 3 to 12 months when used as an adjunctive to NSPT. However, due to the high heterogeneity among the studies, additional well-designed RCTs are needed to provide further evidence on this clinical indication for the use of EMD.

Clinical relevance

The adjunctive use of EMD to NSPT does not seem to additionally improve the clinical outcomes obtained with NSPT alone.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04474-1.

Evaluation of the effectiveness of a novel mouth rinse containing hyaluronic acid and hydrogen peroxide on gingivitis: A randomized pilot controlled trial

Objective

To evaluate and compare the effectiveness of a mouth rinse with hydrogen peroxide (H₂O₂) and hyaluronic acid (HA) versus a placebo mouth rinse on gingivitis.

Material and methods

This was a 21‐day, double blind, randomized, two‐arm parallel allocation placebo‐controlled trial of 50 study participants with a diagnosis of plaque‐induced gingivitis. Patients were randomly allocated to the test group or the placebo group and were assessed at three time points over the course of the study by the same operator, at baseline (T0), 7 days (T1), and 21 days follow‐up (T2). Primary outcomes of the trial were improvement in gingivitis and plaque accumulation.

Results

In both groups there was a decrease in gingival and plaque indices but the combination of the two actives (H₂O₂/HA) proved to be more effective against gingivitis (p = 0.001). Regarding plaque index, the differences between the test product and placebo were not statistically significant (p = 0.084). Besides, the new mouthwash was considered palatable, no adverse events were registered over the 21‐day period.

Conclusions

The H₂O₂ + HA product was more effective in reducing gingivitis when compared to a placebo while no differences were observed for plaque accumulation.

Flapless application of enamel matrix derivative in non-surgical periodontal treatment: A systematic review

BACKGROUND AND OBJECTIVE

To assess the effects of the flapless application of enamel matrix derivative (EMD) in combination with non-surgical periodontal treatment (NSPT) when compared to non-surgical periodontal treatment alone in adult patients.

MATERIAL AND METHODS

An electronic literature search was conducted in MEDLINE, Scopus and Cochrane Library up to March 2021 complemented by a manual search. Human longitudinal studies of >5 participants and at least 3 months follow-up were eligible for inclusion in the review. Clinical outcomes were extracted and pooled. Meta-analysis of the included studies was not possible due to methodological differences.

RESULTS

A total of 1199 publications were identified and reviewed for eligibility. Nine of them fulfilled the inclusion criteria. Eight studies were randomized clinical trials. The clinical findings of the majority of the included studies demonstrated that the adjunctive use of EMD with NSPT could lead to significantly improved treatment outcomes including higher PPD reduction, more CAL gain, more robust BOP reduction, higher number of sites with PPD < 5 mm and more frequent pocket closure which reduces the need for further periodontal surgical treatment. Limited biological, microbiological and histological findings were reported. Minimal adverse events were observed.

CONCLUSION

The flapless application of EMD during NSPT leads to an improved clinical outcome in regards to CAL gain and PPD reduction when compared to conventional treatment alone. The potential effect on the biological and microbiological outcome is unclear.

A thermosensitive gel with an active hyaluronic acid ingredient that contains an octenidine preservation system as an adjunct to scaling and root planning: a randomized prospective clinical study

OBJECTIVES

To evaluate the adjunctive effect of a thermosensitive gel formulation that contains 0.8% oligo hyaluronic acid (HA) combined with a preservation system of octenidine HCl 0.625% and phenoxyethanol to scaling and root planing (SRP) as compared with SRP alone in the treatment of residual pockets of patients with stage 3 periodontitis.

MATERIALS AND METHODS

Thirty-four patients (21 males and 13 females) aged 29-78 years (51.3 ± 13.1) with stage 3 periodontitis were recruited to participate in the present split-mouth study. None of the patients has been previously treated for periodontitis. Plaque index (PI), probing depth (PD), clinical attachment level (CAL), and bleeding on probing (BOP) were evaluated at baseline and at 3 and 6 months post treatment. Full-mouth SRP was performed in all residual pockets ≥ 5 mm. Treatment was performed by means of ultrasonic and hand instruments and lasted 45-60 min. The gel was applied subgingivally in the test sites immediately after SRP (baseline) and 1 month later. The paired t-test for two means was applied to test the statistical significance of the change from baseline within each arm and determine the difference between groups. The level of significance was set at 0.05 for all tests.

RESULTS

Mean PD reductions between baseline and 3 and 6 months were 1.98 mm and 2.79 mm for the test and 1.22 mm and 1.50 mm for the control group, respectively. Comparisons between the test and control groups revealed that SRP + gel yielded statistically significantly higher PD reductions compared to SRP alone (p < 0.0001). Compared to baseline, CAL and BOP values improved statistically significantly in both groups, although the test group presented statistically significantly higher CAL gains and BOP reductions than the control group (P < 0.0001).

CONCLUSION

In residual pockets of stage 3 periodontitis patients, the local application of a thermosensitive gel with an active HA ingredient and a preservation system of octenidine HCl 0.625% in conjunction with SRP may additionally improve the clinical outcomes obtained with SRP alone.

CLINICAL RELEVANCE

A novel HA and octenidine containing thermosensitive gel effectively improved the clinical parameters in stage 3 periodontitis patients over a 6-month period.

The Influence of Hyaluronic Acid Adjunctive Therapy of Periodontitis on Salivary Markers of Oxidative Stress: Randomized, Controlled Clinical Trial

Periodontitis is a common oral disease affecting the tooth-supporting tissues. Bacteria have been long viewed as the main causative factor in its development; however, many investigations have proved that aberrant immune and inflammatory response and the resulting misbalance between the damage caused by reactive oxygen species and the antioxidant capacity of tissues may be an underlying factor in disease progression that reduces healing potential. The objective of the current trial is to assess the outcomes of the addition of hyaluronic acid (HA) to standard non-surgical periodontal therapy (NST) on some major oxidative stress markers in saliva. HA-based gel designed for dental application was used and the measurements were taken after 3 months. HA adjunctive therapy had a significantly greater increase in markers with antioxidant properties as well as total antioxidant capacity compared to standard NST alone. Furthermore, clinically measured levels of gingival inflammation (bleeding on probing-BOP) and periodontal destruction (clinical attachment loss-CAL) were significantly correlated with these markers, and the correlation was negative. This investigation demonstrates that HA may indeed express antioxidant properties and improve the antioxidant capacity of periodontal tissues, thus improving the prognosis for the teeth and the results of periodontal therapy. Further investigations will be necessary to determine the duration of these effects over time.

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.

The effect of hard-type crosslinked hyaluronic acid with particulate bone substitute on bone regeneration: positive or negative?

Purpose

Methods

Results

Conclusions

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.

Biomolecules in Dental Applications: Randomized, Controlled Clinical Trial Evaluating the Influence of Hyaluronic Acid Adjunctive Therapy on Clinical Parameters of Moderate Periodontitis

The biological activity of hyaluronic acid (HA) has been well-researched during the past decades; however, there are few randomized, controlled trials of its clinical effects in periodontal therapy. The purpose of this study was to evaluate the effect of hyaluronic acid on the principal parameters of periodontal healing. A specific, commercially available formulation designed and registered for professional dental application, composed of 16 mg/mL of cross-linked and 2 mg/mL of non-cross-linked HA, was used as an adjunctive to non-surgical periodontal therapy, and clinical parameters were evaluated after 3 months. The addition of HA to periodontal therapy demonstrated more favorable clinical results regarding reduction in inflammation, measured by bleeding on probing (-6% compared to the control group) and gain in periodontal attachment (1 mm more than control group), while it had no effect on probing depth reduction. No side effects were reported. Our study demonstrated that HA is a safe and easy-to-use biological agent; due to its wide array of properties, it may significantly improve the results of periodontal therapy. However, more long-term studies are needed to investigate whether these favorable effects remain over time.

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.

Changes in clinical parameters following adjunctive local sodium hypochlorite gel in minimally invasive nonsurgical therapy (MINST) of periodontal pockets: a 6-month randomized controlled clinical trial

BACKGROUND

The mechanical disruption and removal of the subgingival biofilm represent the most important step in the treatment of periodontitis. However, in deep periodontal pockets, mechanical removal of the subgingival biofilm is difficult and frequently incomplete. Preliminary findings indicate that the use of amino acid buffered sodium hypochlorite (NaOCl) gel may chemically destroy the bacterial biofilm and facilitate its mechanical removal.

OBJECTIVES

To clinically evaluate the efficacy of minimally invasive nonsurgical therapy (MINST) of periodontal pockets with or without local application of an amino acid buffered sodium hypochlorite (NaOCl) gel.

MATERIALS AND METHODS

Forty untreated patients diagnosed with severe/advanced periodontitis (i.e. stage III/IV) with a slow/moderate rate of progression (i.e. grade A/B) were randomly allocated in two treatment groups. In the test group, the periodontal pockets were treated by means of MINST and NaOCl gel application, while in the control group, treatment consisted of MINST alone. Full-mouth plaque scores (FMPS), full-mouth bleeding scores (FMBS), probing depths (PD), clinical attachment levels (CAL) and gingival recessions (GR) were assessed at baseline and at 6 months following therapy. The primary outcome variable was PD reduction at sites with PD ≥ 5 mm at baseline.

RESULTS

At 6 months, statistically significant differences between the two groups were found (p = 0.001) in terms of PD and CAL change. No statistically significant differences were found in terms of GR (p = 0.81). The number of sites with PD ≥ 5 mm and BOP (+) decreased statistically significantly (p = 0.001), i.e. from 85.3 to 2.2% in the test group and from 81.6 to 7.3% in the control group, respectively. Statistically significant differences between test and control groups were recorded at 6 months (p = 0.001). MINST + NaOCl compared to MINST alone decreased statistically significantly (p = 0.001) the probability of residual PDs ≥ 5 mm with BOP- (14.5% vs 18.3%) and BOP+ (2.2% vs. 7.2%).

CONCLUSIONS

Within their limits, the present results indicate that (a) the use of MINST may represent a clinically valuable approach for nonsurgical therapy and (b) the application of NaOCl gel in conjunction with MINST may additionally improve the clinical outcomes compared to the use of MINST alone.

CLINICAL RELEVANCE

In patients with untreated periodontitis, treatment of deep pockets by means of MINST in conjunction with a NaOCl gel may represent a valuable approach to additionally improve the clinical outcomes obtained with MINST alone.

Effect of root conditioning agents hyaluronic acid, EDTA and chlorhexidine on the attachment of human gingival fibroblasts to healthy root surface

Background

The gold standard treatment of periodontal diseases is scaling and root planing (SRP). Different adjunctive root conditioning agents such as hyaluronic acid (HA), ethylenediaminetetraacetic acid (EDTA), and chlorhexidine (CHX) have been used with SRP to improve the smear layer removal and the healing of periodontal tissues. The aim of this study was to compare the effect of manual scaling with or without HA, EDTA, or CHX root conditioning on the attachment and viability of human gingival fibroblasts (GF).

Methods

Fifteen healthy single rooted teeth were co llected and divided randomly into a scaled (n = 12) and non-scaled control group (n = 3). The scaled roots were subdivided equally into four groups; the first group did not receive any chemical treatment, while the remaining groups were treated with the conditioning agents HA or 17% EDTA or 0.2% CHX gel. Gingival fibroblasts were seeded on the top of each root and incubated for 48 h to allow attachment to the roots. The viability of fibroblasts attached to the root surface was assessed using MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) cell viability assay.

Results

The cell viability was the highest in the scaled only group (p = 0.0001) while the lowest was in the scaled with EDTA group (p > 0.05). The scaled group was the highest followed by the HA and CHX groups, while the EDTA group showed the lowest mean value.

Conclusion

SRP remains the superior method for regaining cell attachment to the root surface, leading to better periodontal health, and adjunctive therapies did not enhance the GF attachment to the root surface beyond the effect of SRP. Further studies are needed to investigate the effect of root conditioning agents on periodontally diseased teeth in vitro and compare them in vivo.

Treatment of Residual Periodontal Pockets Using a Hyaluronic Acid-Based Gel: A 12 Month Multicenter Randomized Triple-Blinded Clinical Trial

The aim of the present study was to evaluate the adjunctive effect of hyaluronic acid (HA) gel in the treatment of residual periodontal pockets over a 12-month period. Periodontal patients presenting at least one residual periodontal pocket 5-9 mm of depth in the anterior area were recruited from six university-based centers. Each patient was randomly assigned to subgingival instrumentation (SI) with the local adjunctive use of HA for test treatment or adjunctive use of local placebo for control treatment at baseline and after 3 months. Clinical parameters ( )probing depth (PD), bleeding on probing (BoP), plaque index (PI), recession (REC), clinical attachment level (CAL)) and microbiological samples for the investigation of the total bacterial count (TBC) and presence of specific bacterial species (Porphyromonas gingivalis, Treponema denticola, Tannerella forsythia, Fusobacterium nucleatum) were taken at baseline and every 3 months, until study termination. PD was determined as the primary outcome variable. From a total of 144 enrolled, 126 participants (53 males, 73 females) completed the entire protocol. Both treatments resulted in statistically significant clinical and microbiological improvements compared to baseline. Although the local application of HA showed a tendency for better results, there was a lack of statistically significant differences between the groups.

Biomaterials for Periodontal and Peri-Implant Regeneration

Periodontal and peri-implant regeneration is the technique that aims to restore the damaged tissue around teeth and implants. They are surrounded by a different apparatus, and according to it, the regenerative procedure can differ for both sites. During the last century, several biomaterials and biological mediators were proposed to achieve a complete restoration of the damaged tissues with less invasiveness and a tailored approach. Based on relevant systematic reviews and articles searched on PubMed, Scopus, and Cochrane databases, data regarding different biomaterials were extracted and summarized. Bone grafts of different origin, membranes for guided tissue regeneration, growth factors, and stem cells are currently the foundation of the routinary clinical practice. Moreover, a tailored approach, according to the patient and specific to the involved tooth or implant, is mandatory to achieve a better result and a reduction in patient morbidity and discomfort. The aim of this review is to summarize clinical findings and future developments regarding grafts, membranes, molecules, and emerging therapies. In conclusion, tissue engineering is constantly evolving; moreover, a tailor-made approach for each patient is essential to obtain a reliable result and the combination of several biomaterials is the elective choice in several conditions.

Hyaluronic acid vs. physiological saline for enlarging deficient gingival papillae: a randomized controlled clinical trial and an in vitro study

Background

loss of the interdental papillae leads to the formation of a black triangle, which compromises smile esthetics and contributes to food impaction and plaque accumulation. The aim of this study was to evaluate the efficacy of the injection of hyaluronic acid (HA) and compare it to that of physiological saline solution in the restoration of deficient gingival papillae in vivo and in vitro.

Methods

Twenty-four patients with 68 deficient gingival papillae were recruited for this clinical trial with a split-mouth design. The deficient gingival papillae on one side of the anterior maxilla were injected with HA, and those on the other side were injected with physiological saline solution. The heights of the gingival papillae and the areas of the black triangles were measured from clinical photographs obtained before and 6 and 12 months after treatment. Additionally, the proliferation and migration of gingival fibroblasts were evaluated after HA and physiological saline treatment by an in vitro study.

Results

the results revealed that the injection of HA yielded 0.198 and 0.28 mm gingival papilla increasement at 6 and 12 months, respectively, relative to the baseline (P<0.05). However, deficient gingival papillae also grew by 0.278 mm at 12 months in the group that received physiological saline solution (P<0.05). The injection of HA significantly improved deficient gingival papillae 6 months earlier than the injection of physiological saline solution. HA also significantly accelerated the proliferation and migration of gingival fibroblasts in vitro.

Conclusions

The present study confirms that the injection of HA could increase the height of gingival papillae for improving gingival papilla defects. However, the effect is not superior to that of physiological saline solution. This trial was registered in the Chinese Clinical Trial Registry (ChiCTR-ONC-17011781) (28/06/2017). http://www.chictr.org.cn/showproj.aspx?proj=19931

Influence of Materials Properties on Bio-Physical Features and Effectiveness of 3D-Scaffolds for Periodontal Regeneration

Periodontal diseases are multifactorial disorders, mainly due to severe infections and inflammation which affect the tissues (i.e., gum and dental bone) that support and surround the teeth. These pathologies are characterized by bleeding gums, pain, bad breath and, in more severe forms, can lead to the detachment of gum from teeth, causing their loss. To date it is estimated that severe periodontal diseases affect around 10% of the population worldwide thus making necessary the development of effective treatments able to both reduce the infections and inflammation in injured sites and improve the regeneration of damaged tissues. In this scenario, the use of 3D scaffolds can play a pivotal role by providing an effective platform for drugs, nanosystems, growth factors, stem cells, etc., improving the effectiveness of therapies and reducing their systemic side effects. The aim of this review is to describe the recent progress in periodontal regeneration, highlighting the influence of materials' properties used to realize three-dimensional (3D)-scaffolds, their bio-physical characteristics and their ability to provide a biocompatible platform able to embed nanosystems.

Clinical and radiographic evaluation of 0.8% hyaluronic acid as an adjunct to open flap debridement in the treatment of periodontal intrabony defects: randomized controlled clinical trial

OBJECTIVES

Present study aimed to evaluate and compare the clinical and radiographic efficacy of 0.8% hyaluronic acid (HA) gel as an adjunct to open flap debridement (OFD) versus open flap debridement (OFD) alone in the treatment of periodontal intrabony defects.

MATERIALS AND METHODS

This randomized, controlled, split-mouth, clinical trial included 20 chronic periodontitis (stage II or III (grades A to B)) patients, having at least two contralateral intrabony defects. Forty bilateral intrabony defects (20 in each group) were randomly divided into test (0.8% HA gel + OFD) and control (OFD + placebo) groups. Clinical parameters evaluated at baseline, 6-months, and 12-months were plaque index (PI), gingival index (GI), probing depth (PD), clinical attachment level (CAL), and gingival recession (GR). Using cone beam computed tomography (CBCT), radiographic parameters were evaluated at baseline and 12 months. This included bone defect fill (DF), alveolar crest changes (ACC), and defect resolution (DR). CAL served as the primary outcome variable.

RESULTS

After 12 months, the test group showed significantly greater CAL gain (5.1 ± 1.2 versus 4.05 ± 1.19 mm) and bone defect fill (DF) (5.67 ± 2.01 versus 4.49 ± 1.78 mm) compared to the control group. Mean PD reduction in the test group (5.3 ± 1.2 versus 4.35 ± 0.81 mm) was statistically significant compared to the control group at 12-month period. The control group showed statistically significant increase in GR (1.2 ± 0.76 versus 0.7 ± 0.73 mm) compared to the test group after 12 months.

CONCLUSION

Application of hyaluronic acid gel in conjunction with open flap debridement resulted in enhanced clinical and radiographic outcomes compared to open flap debridement alone.

CLINICAL RELEVANCE

Adjunctive application of HA gel in open flap debridement may improve clinical and radiographic outcomes.

CLINICAL TRIAL REGISTERED NUMBER

CTRI/2018/03/012334.

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

Aim

To clinically and histologically evaluate in dogs the healing of gingival recessions treated with coronally advanced flap (CAF) with or without cross‐linked hyaluronic acid (HA).

Materials and methods

Gingival recession defects were surgically created on the vestibular side of both maxillary canines in 8 dogs. After 8 weeks of plaque accumulation, the 16 chronic defects were randomly treated with either CAF alone or CAF and HA‐gel (CAF/HA). Clinical and histological outcomes were evaluated at 10 weeks post‐surgically.

Results

Compared to baseline, the clinical measurements at 10 weeks revealed a statistically significant decrease in gingival recession for both CAF (p < 0.01) and CAF/HA (p < 0.001) groups. Statistically significant differences were found in clinical attachment level (p < 0.05) and width of gingival recession (p < 0.01) favouring the CAF/HA group. Bone formation was statistically significantly greater in the CAF/HA group than in the CAF group (1.84 ± 1.16 mm vs., 0.72 ± 0.62 mm, respectively, p < 0.05). Formation of cementum and connective tissue attachment were statistically significantly higher in the CAF/HA group compared with the CAF group (i.e. 4.31 ± 1.78 mm versus 2.40 ± 1.35 mm and 1.69 ± 0.98 mm versus 0.74 ± 0.68 mm, respectively (p < 0.05)).

Conclusions

The present data have for the first time provided histologic evidence for periodontal regeneration of gingival recession defects following treatment with CAF and HA.

Clinical relevance

The use of HA in conjunction with CAF may represent a novel modality for treating gingival recession defects.

Healing of intrabony defects following regenerative surgery by means of single-flap approach in conjunction with either hyaluronic acid or an enamel matrix derivative: a 24-month randomized controlled clinical trial

Objectives

The aim of this randomized controlled clinical trial was to compare the clinical outcomes obtained in intrabony defects following regenerative periodontal surgery using the single-flap approach (SFA) in conjunction with either hyaluronic acid (HA) or enamel matrix derivative (EMD).

Materials and methods

Thirty-two intrabony defects in 32 healthy subjects were randomly assigned: HA (test group) or EMD (control group). Clinical attachment level (CAL), probing depth (PD), gingival recession (REC), and bleeding on probing (BOP) were recorded at baseline,12, 18, and 24 months after surgery.

Results

At 24 months, both treatments resulted in statistically significant clinical improvements evidenced by PD-reduction and CAL-gain (p<0.001). The mean CAL-gain was 2.19±1.11 mm in the test and 2.94±1.12 mm in the control sites (p=0.067). PD-reduction was statistically significantly higher for the control group (4.5±0.97 mm) than the test group (3.31±0.70 mm), (p=0.001). CAL-gain ≤ 3 mm was observed in 87.5% and in 62.5% of the test and control sites, respectively. Test sites showed slightly lower REC values than the control sites. No statistically significant differences were found for BOP between treatments.

Conclusions

The present findings indicate that both treatments led to statistically significant clinical improvements compared to baseline, although the application of EMD resulted in statistically significantly higher PD-reduction compared to the use of HA.

Clinical relevance

The use of HA in conjunction with a SFA resulted in significant PD-reduction and CAL-gain, pointing to the potential clinical relevance of this material in regenerative periodontal surgery.

Hyaluronic acid reduces inflammation and crevicular fluid IL-1β concentrations in peri-implantitis: a randomized controlled clinical trial

Purpose

This study investigated the effects of hyaluronic acid (HA) on peri-implant clinical variables and crevicular concentrations of the proinflammatory biomarkers interleukin (IL)-1β and tumor necrosis factor (TNF)-α in patients with peri-implantitis.

Methods

A randomized controlled trial was conducted in peri-implantitis patients. Patients were randomized to receive a 0.8% HA gel (test group), an excipient-based gel (control group 1), or no gel (control group 2). Clinical periodontal variables and marginal bone loss after 0, 45, and 90 days of treatment were assessed. IL-1β and TNF-α levels in crevicular fluid were measured by enzyme-linked immunosorbent assays at baseline and after 45 days of treatment. Clustering analysis was performed, considering the possibility of multiple implants in a single patient.

Results

Sixty-one patients with 100 dental implants were assigned to the test group, control group 1, or control group 2. Probing pocket depth (PPD) was significantly lower in the test group than in both control groups at 45 days (control 1: 95% CI, −1.66, −0.40 mm; control 2: 95% CI, −1.07, −0.01 mm) and 90 days (control 1: 95% CI, −1.72, −0.54 mm; control 2: 95% CI, −1.13, −0.15 mm). There was a trend towards less bleeding on probing in the test group than in control group 2 at 90 days (P=0.07). Implants with a PPD ≥5 mm showed higher levels of IL-1β in the control group 2 at 45 days than in the test group (P=0.04).

Conclusions

This study demonstrates for the first time that the topical application of a HA gel in the peri-implant pocket and around implants with peri-implantitis may reduce inflammation and crevicular fluid IL-1β levels.

Trial Registration

ClinicalTrials.gov Identifier: NCT03157193

The Effectiveness of Hyaluronic Acid in Controlling Pain, Edema, and Trismus After Extraction of Third Molars: Systematic Review and Meta-Analysis

This study aimed to evaluate the clinical evidence of hyaluronic acid (HA) in minimizing inflammatory parameters such as pain, edema, and trismus after extraction of third molar (3M). An electronic search was conducted in 4 databases. The eligibility criteria included clinical trials that used HA compared with placebo or no treatment after 3M surgeries. The search strategy resulted in 752 references, of which 5 studies were included comprising 271 patients. Regarding the risk of bias analysis, most criteria were rated as low or unclear risk of bias. All the evaluated studies were classified as low risk of bias in the selective reporting criteria. The final quantitative analysis of the variables showed that the use of HA resulted in a greater reduction of pain levels on the third (mean difference = -0.68; 95% confidence interval, -1.20 to -0.17) and seventh (mean difference = -0.36; 95% confidence interval, -0.64 to -0.09) postoperative days. There are no differences between the analyzed groups in relation to trismus. It was not possible to conduct meta-analysis for the edema variable because of the heterogeneity of the methods of measurement. The results suggest that HA seems to provide a lower average pain on the third and seventh postoperative days and has no influence on postoperative trismus after extraction of 3Ms; however, more research with stronger methodology is needed to determine its efficacy.

Use of Platelet-Rich Fibrin in the Treatment of Grade 2 Furcation Defects: Systematic Review and Meta-Analysis

In periodontitis patients, furcation defects are crucial sites to regenerate due to their complex anatomy. Various modern surgical techniques and use of biomaterials have been suggested in the literature. Among all, platelet-rich fibrin (PRF) has potential in tissue regeneration thanks to its role in the release of growth factors. Therefore, the purpose of this study was to evaluate the beneficial effect of the addition of PRF to open flap debridement (OFD) or as an adjuvant to other biomaterials such as bone grafts in the treatment of grade 2 mandibular furcation defects. Systematic research was carried out on the databases Medline, Scopus, Embase, and Cochrane Library and registered on PROSPERO (CRD42020167662). According to the PICO guidelines by Cochrane, randomized trials and prospective non-randomized trials were evaluated, with a minimum follow-up period of 6 months. The inclusion criteria were the absence of systemic diseases, non-smoking patients, and a population aged from 18 to 65 years. Vertical pocket probing depth (PPD), vertical clinical attachment level (VCAL), and gingival recession (REC) were the primary outcomes. Vertical furcation depth (VFD), and the percentage of bone defect fill (%v-BDF) were considered as secondary outcomes. A meta-analysis of the primary and secondary outcomes was performed. Publication bias was assessed through a funnel plot. Eighty-four articles were initially extracted. Eight randomized clinical trials were analyzed according to the exclusion and inclusion criteria. The Quality assessment instrument (QAI) revealed four articles at low risk of bias, one at moderate, and three at high risk of bias. The metanalysis showed significant data regarding PPD, VCAL, VFD and %v-BDF in the comparison between PRF + OFD vs. OFD alone. The adjunct of PRF to a bone graft showed a significant difference for VCAL and a not statistically significant result for the other involved parameters. In conclusion, the adjunctive use of PRF to OFD seems to enhance the periodontal regeneration in the treatment of grade 2 furcation defects. The combination of PRF and bone graft did not show better clinical results, except for VCAL, although the amount of literature with low risk of bias is scarce. Further well-designed studies to evaluate the combination of these two materials are therefore needed.

Biological molecules in dental applications: hyaluronic acid as a companion biomaterial for diverse dental applications

Objectives

The application of hyaluronic acid (HA) in dental treatments is relatively new, and modified-HA products can be vastly different from each other. This study aims to provide a basis for bridging specific characteristics of HA with its potential applications in dental treatments, evaluating and comparing different types of HA products and for future research on HA applications in dentistry.

Data sources

Information from the existing literature on HA applications has been cited.

Study selection

Furthermore, this study is specifically oriented to provide oral health care providers with a scientific basis for HA use along with the clinical aspects of HA.

Conclusions

Outcomes from existing and future studies cannot be generalised for HA use in dental applications. Therefore, we have proposed a scheme to bridge HA specific characteristics to its applications in dental treatments and compare different HA products used for the same clinical application to identify the most suitable one.

Clinical significance

Highlighting the use of HA in dental treatments and providing a basis for developing new methods, protocols, and products specifically oriented for dentistry.