Cytokine and microbial profiles in relation to the clinical outcome following treatment of peri-implantitis

Characterization of oral biomarkers during early healing at augmented dental implant sites

AIM

The aim of this study is to assess early wound healing expression of local angiogenic biomarkers following connective tissue graft (CTG) at dental implant sites.

METHODS

Twenty-eight subjects with single dental implants exhibiting a soft tissue dehiscence were included and randomly treated with CTG, either with coronally advanced flap (CAF) or with tunnel technique (TUN). Peri-implant crevicular fluid (PICF) was collected at the midfacial and midlingual aspect of the implant sites at baseline and at 3, 7, 14, 30, and 90 days after the surgical intervention. The expression of angiogenin (ANG), fibroblast growth factor-2 (FGF-2), platelet-derived growth factor (PDGF), tissue inhibitor of metalloproteinases-2 (TIMP-2), and vascular endothelial growth factor (VEGF) was investigated over a period of 3 months. Patient-reported outcomes, clinical measurements, and ultrasonography scans at multiple time points were also evaluated.

RESULTS

The longitudinal regression revealed a significant difference in the expression of VEGF and TIMP-2 between CAF- and TUN-treated sites over 3 months (p = .033 and p = .004, respectively), whereas no significant differences were observed for ANG, FGF-2 and PDGF between the two groups. At 7 days, a direct correlation was observed between ANG levels and ultrasonographic color velocity in the CAF group (p < .001) and between ANG levels and ultrasonographic color power in the TUN group (p = .028). VEGF levels and ultrasonographic mean perfused area of the CTG were significantly correlated at the 7-day time point (p < .001 for both CAF and TUN). The expression of VEGF at 7 days was directly associated with mucosal thickness gain at 1 year (p < .001 for both groups). Early TIMP-2 expression showed an inverse correlation with time to recovery (p = .002). TIMP-2 levels at 3 months exhibited inverse correlations with mean dehiscence coverage (p = .004) and the rate of complete dehiscence coverage (p = .012).

CONCLUSION

PICF biomarkers can be used to monitor early wound healing events following soft tissue grafting at implant sites. VEGF and TIMP-2 showed correlations with the 1-year clinical and volumetric outcomes, as well as with post-operative patient-reported outcomes and Doppler Ultrasonographic tissue perfusion-related parameters.

A randomised clinical trial comparing a surgical approach for treatment of peri-implantitis to non-surgical debridement with adjunctive diode laser therapy

OBJECTIVES

To evaluate the efficacy of non-surgical debridement with repeated diode laser application in comparison to surgical treatment for management of peri-implantitis.

MATERIALS AND METHODS

Forty patients diagnosed with peri-implantitis were randomised into two groups. The test group received mechanical debridement and repeated diode laser therapy at Days 0, 7 and 14. The control group received mechanical debridement at Day 0 followed by surgical treatment at Day 14. Clinical evaluations were performed at baseline, 3 and 12 months.

RESULTS

Thirty-six participants (test n = 17, control n = 19) completed the 12-month observation period. Laser treatment failed in 4 cases (23.5%); of which 3 implants lost osseointegration and one necessitated surgical treatment due to progressively increasing probing depths (PD) and bone loss. In comparison, the control group showed a 100% survival rate with a statistically significant difference between the two groups (p = 0.04). Therefore, thirty-two participants were examined at the final evaluation (test n = 13, control n = 19). Twenty-two implants (57.9%) showed complete disease resolution without significant differences between the groups. The test group reported significantly lower post-operative discomfort on the visual analogue scale (VAS). At 3 months, both groups showed clinical signs of healing with reduction in probing depths (PD) and bleeding upon probing. Surgical treatment resulted in significantly lower PDs (control 3.7 mm [3.2, 4.0], test 4.5 mm [3.8, 4.8]), but recession was significantly higher (control 0.5 mm [0.3, 1.2], test 0 mm [0.0, 0.3]). At the final reevaluation, PD values remained significantly lower in the control group; 3.3 mm [3.1, 3.9] compared to 4.3 mm [3.7, 4.8] for the test group, but the difference in mucosal recession fell below the level of significance. Marginal bone levels improved after one year without significant differences between the two groups (Test = 3.5 mm [2.8, 4.6] at baseline and 1.5 mm [1.0, 4.4] at one year, Control = 2.8 mm [2.5, 3.1] at baseline and 1.4 mm [1.0, 2.6] at one year).

CONCLUSION

Surgical approaches for management of peri-implantitis demonstrated significant benefits over laser therapy in terms of treatment success and PD reduction. Nevertheless, diode laser therapy, as described in this study, could represent a minimally invasive alternative for treatment of non-advanced peri-implantitis defects.

CCR2 is a potential therapeutic target in peri-implantitis

AIM

CCR2 (C-C chemokine receptor type 2) plays a crucial role in inflammatory and bone metabolic diseases; however, its role in peri-implantitis remains unclear. This study aimed to explore whether CCR2 contributes to peri-implantitis and the treatment effects of cenicriviroc (CVC) on peri-implant inflammation and bone resorption.

MATERIALS AND METHODS

The expression of CCR2 was studied using clinical tissue analysis and an in vivo peri-implantitis model. The role of CCR2 in promoting inflammation and bone resorption in peri-implantitis was evaluated in Ccr2-/- mice and wild-type mice. The effect of CVC on peri-implantitis was evaluated using systemic and local dosage forms.

RESULTS

Human peri-implantitis tissues showed increased CCR2 and CCL2 levels, which were positively correlated with bone loss around the implants. Knocking out Ccr2 in an experimental model of peri-implantitis resulted in decreased monocyte and macrophage infiltration, reduced pro-inflammatory cytokine generation and impaired osteoclast activity, leading to reduced inflammation and bone loss around the implants. Treatment with CVC ameliorated bone loss in experimental peri-implantitis.

CONCLUSIONS

CCR2 may be a potential target for peri-implantitis treatment by harnessing the immune-inflammatory response to modulate the local inflammation and osteoclast activity.

Effect of laser-assisted reconstructive surgical therapy of peri-implantitis on protein biomarkers and bacterial load

OBJECTIVES

This randomized clinical trial assessed changes in protein biomarker levels and bacterial profiles after surgical reconstructive therapy of peri-implantitis and investigated whether the adjunctive use of Er:YAG laser impacts protein biomarker and microbial outcomes.

MATERIALS AND METHODS

Twenty-four patients received surgical reconstructive therapy for peri-implantitis with guided bone regeneration following mechanical debridement with (test) or without (control) the adjunctive irradiation of Er:YAG laser. Bacterial and peri-implant crevicular fluid (PICF) samples were collected over 6 months and analyzed with bacterial qPCR and luminex multiplex assays.

RESULTS

Surgical reconstructive treatment significantly affected the concentration of PICF protein biomarkers, including a 50% reduction in IL-1β between 2 and 4 weeks (p < .0001). Both MMP-9 (p < .001) and VEGF (p < .05) levels steadily decreased after treatment. In the laser group, the peak increase in IL-1β was attenuated at 2 weeks, followed by significant reduction in MMP-9 (p < .01) and VEGF (p < .05) across all follow-up appointments compared with the control nonlaser group. The total bacterial load was reduced 2 weeks after treatment, especially in the laser group, but recolonized to presurgical levels after 4 weeks in both groups (p < .01). The composition of selective pathogens varied significantly over the follow-up, but recolonization patterns did not differ between groups.

CONCLUSIONS

Reconstructive therapy of peri-implantitis significantly altered PICF protein biomarker and microbial levels during the healing process. The adjunctive use of Er:YAG laser significantly modulated the inflammatory response through reduced levels of MMP-9 and VEGF during the postsurgical period. The bacterial load was reduced immediately after therapy, but recolonization was observed by 4 weeks in both groups.

Biomarker Expression of Peri-Implantitis Lesions before and after Treatment: A Systematic Review

The need to predict, diagnose and treat peri-implant diseases has never been greater. We present a systematic review of the literature on the changes in the expression of biomarkers in peri-implant crevicular fluid (PICF) before and after treatment of peri-implantitis. Bacterial composition, clinical and radiographic parameters, and systemic biomarkers before and after treatment are reported as secondary outcomes. A total of 17 studies were included. Treatment groups were non-surgical treatment or surgical treatment, either alone or with adjunctive therapy. Our findings show that non-surgical treatment alone does not influence biomarker levels or clinical outcomes. Both adjunctive photodynamic therapy and local minocycline application resulted in a reduction of interleukin (IL)-1β and IL-10 twelve months after treatment. Non-surgical treatments with adjunctive use of lasers or antimicrobials were more effective at improving the clinical outcomes in the short-term only. Access flap debridement led to matrix metalloproteinase (MMP)-8 and tumour necrosis factor-α reduction twelve months post-surgery. Surgical debridement with adjunctive antimicrobials achieved a decrease in MMP-8 at three months. Adjunctive use of Emdogain^™ (EMD) was associated with a reduction in 40 PICF proteins compared to access flap surgery alone. Surgical interventions were more effective at reducing probing pocket depth and bleeding on probing both in the short- and long-term. Surgical treatment in combination with EMD was found to be more effective in resolving inflammation up to twelve months.

Asperuloside Prevents Peri-Implantitis via Suppression of NF-κB and ERK1/2 on Rats

Peri-implantitis is characterized by inflammatory cell infiltration and hyperactivation of the osteoclasts surrounding dental implants which can result in bone resorption and ultimately implant failure. Therefore, coordinating the activity of inflammatory response and bone-resorbing osteoclasts is crucial for the prevention of peri-implantitis. Asperuloside (ASP), an iridoid glycoside, has significant anti-inflammatory activities, suggesting the great potential in attenuating peri-implantitis bone resorption. A ligature-induced peri-implantitis model in the maxilla of rats was established, and the effects of ASP on preventing peri-implantitis were evaluated after four weeks of ligation using micro-CT and histological staining. RT-PCR, western blotting, tartrate-resistant acid phosphatase (TRAP), and immunofluorescent staining were conducted on osteoclasts to confirm the mechanisms of ASP on osteoclastogenesis. The results show that ASP could lead to attenuation of alveolar bone resorption in peri-implantitis by inhibiting osteoclast formation and decreasing pro-inflammatory cytokine levels in vivo. Furthermore, ASP could inhibit osteoclastogenesis by downregulating expression levels of transcription factors nuclear factor of activated T-cell (NFATc1) via restraining the activations of nuclear factor kappa beta (NF-κB) and the phosphorylation of extracellular signal-related kinase 1/2 (ERK1/2). In conclusion, ASP could significantly attenuate bone resorption in peri-implantitis via inhibition of osteoclastogenesis by suppressing NF-κB and ERK1/2 signaling pathways activations.

Clinical, Microbiological, and Biochemical Impact of the Surgical Treatment of Peri-Implantitis-A Prospective Case Series

Background: The aim of this study, a prospective case series, was to evaluate the clinical, microbiological, and biochemical impact of the surgical treatment of peri-implantitis. Methods: Thirty subjects with diagnosis of peri-implantitis were treated following a surgical protocol including access flaps, surface decontamination with ultrasonics and glycine powder air-polishing, and systemic antibiotics. Disease resolution was defined by the composite outcome including presence of probing depths (PD) ≤5 mm, absence of bleeding on probing (BoP)/suppuration, and no additional radiographic bone loss (>1 mm). Regression analysis was used to evaluate the patient-, implant-, and prosthetic-related factors possibly influencing treatment outcomes. Results: Patients were evaluated at 6 months post treatment, demonstrating statistically significant reductions in PD (2.14 ± 1.07 mm) and increase in mucosal recession (1.0 ± 0.77 mm). Plaque, BoP, and suppuration were also reduced by 40.56%, 62.22%, and 7.78%, respectively. Disease resolution was achieved in 56.67% of patients. No significant changes were detected in microbiological parameters except for a significant reduction in proportions of Parvimonas micra. Similarly, the levels of the biomarker interleukin-8 in crevicular fluid were significantly lower at 6 months. Conclusions: The proposed surgical treatment of peri-implantitis demonstrated statistically significant clinical improvements although the impact on microbiological and biochemical parameters was scarce.

Peri-Implant Surgical Treatment Downregulates the Expression of sTREM-1 and MMP-8 in Patients with Peri-Implantitis: A Prospective Study

sTREM-1 and its ligand PGLYRP1 play an essential role in the inflammatory process around teeth and implants. In this study, we aimed to evaluate the impact of peri-implant treatment on the salivary levels of the sTREM-1/PGLYRP-1/MMP-8 axis after 3 months. A total of 42 participants (with a mean age of 61 years old ± 7.3) were enrolled in this longitudinal study, 24 having peri-implant mucositis (MU) and 18 having peri-implantitis (PI). Clinical peri-implant parameters, such as probing pocket depth (PPD), % of plaque, and bleeding on probing (BOP), and the whole unstimulated saliva samples were evaluated at baseline and 3 months after treatment. The MU group received nonsurgical peri-implant treatment, while the PI group received open-flap procedures. The levels of sTREM-1, PGLYRP-1, MMP-8, and TIMP-1 were analyzed using enzyme-linked immunosorbent assays. BOP, plaque levels, and PPD significantly reduced after treatment in both groups. A significant decrease in the salivary levels of sTREM-1, MMP-8, and TIMP-1 in the PI group and PGLYRP1 and TIMP-1 in the MU group were observed. Salivary levels of sTREM-1 were significantly reduced in patients with PI but not with MU. Additionally, peri-implant treatment had a significantly higher impact on MMP-8 reduction in patients with PI than in those with MU.

Identification of Potential Genetic Biomarkers and Target Genes of Peri-Implantitis Using Bioinformatics Tools

Objectives

To investigate potential genetic biomarkers of peri-implantitis and target genes for the therapy of peri-implantitis by bioinformatics analysis of publicly available data.

Methods

The GSE33774 microarray dataset was downloaded from the Gene Expression Omnibus (GEO). The differentially expressed genes (DEGs) between peri-implantitis and healthy gingival tissues were identified using the GEO2R tool. GO enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis were performed using the DAVID database and the Metascape tool, and the results were expressed as a bubble diagram. The protein-protein interaction network of DEGs was constructed using the Search Tool for the Retrieval of Interacting Genes (STRING) and visualized using Cytoscape. The hub genes were screened by the cytoHubba plugin of Cytoscape. The potential target genes associated with peri-implantitis were obtained from the DisGeNET database and the Open Targets Platform. The intersecting genes were identified using the Venn diagram web tool.

Results

Between the peri-implantitis group and the healthy group, 205 DEGs were investigated including 140 upregulated genes and 65 downregulated genes. These DEGs were mainly enriched in functions such as the immune response, inflammatory response, cell adhesion, receptor activity, and protease binding. The results of KEGG pathway enrichment analysis revealed that DEGs were mainly involved in the cytokine-cytokine receptor interaction, pathways in cancer, and the PI3K-Akt signaling pathway. The intersecting genes, including IL6, TLR4, FN1, IL1β, CXCL8, MMP9, and SPP1, were revealed as potential genetic biomarkers and target genes of peri-implantitis.

Conclusions

This study provides supportive evidence that IL6, TLR4, FN1, IL1β, CXCL8, MMP9, and SPP1 might be used as potential target biomarkers for peri-implantitis which may provide further therapeutic potentials for peri-implantitis.

Melatonin prevents peri‑implantitis via suppression of TLR4/NF-κB

Peri‑implantitis, which is characterized by peri‑implant mucositis and alveolar bone resorption, significantly shortens the service life of dental implants. Melatonin is well-known for its anti-inflammatory and osteoprotective activities. Nevertheless, the effects and mechanisms of melatonin to prevent peri‑implantitis remain unknown. In this study, the lipopolysaccharide-induced peri‑implantitis model was established after the titanium implants were osseointegrated, and the rats received daily administrations of melatonin. The gingival fibroblasts and osteoclasts/osteoblasts were also co-cultured to simulate the inflammatory environment in vitro. We found that prophylactic administration of melatonin decreased proinflammatory cytokine levels and osteoclast numbers, attenuated alveolar bone resorption, and reduced the incidence of peri‑implantitis in vivo. Furthermore, melatonin suppressed osteoclastic formation and function in the inflammatory co-culture environment, while melatonin promoted osteoblastic differentiation and function in the in vitro model. Mechanistically, melatonin reduced TLR4 protein levels, and inhibited activation of NF-κB to downregulate the levels of TNF, IL-1β, and IL-6. These data showed that melatonin was a potent agent to prevent peri‑implantitis through inhibiting TLR4/NF-κB signaling. Our findings provide a novel strategy to prevent peri‑implantitis, and expand the applications of melatonin. STATEMENT OF SIGNIFICANCE: Dental implants have become the first choice for restoring partial and full edentulism, but its service life is seriously affected by peri‑implantitis. Exploration of novel and effective approaches to prevent peri‑implantitis is an important and urgent need. In the present study, we have reported for the first time that prophylactic administration of melatonin delayed the occurrence and reduced the incidence of peri‑implantitis by decreasing proinflammatory cytokine levels, inhibiting osteoclastogenesis, and promoting osteogenesis. The study is expected to have an important significance on the prevention of peri‑implantitis.

Surgical treatment of peri-implantitis with or without a deproteinized bovine bone mineral and a native bilayer collagen membrane: A randomized clinical trial

AIM

To assess whether the use of deproteinized bovine bone mineral (DBBM) and native bilayer collagen membrane (NBCM) improved healing of peri-implantitis-related bone defects at 12 months.

MATERIALS AND METHODS

In a multi-centre, randomized clinical trial, 32 individuals received surgical debridement (control group [CG]), and 34 received adjunct use of DBBM and NBCM (test group [TG]). Radiographic defect fill (RDF), probing pocket depth (PPD), bleeding on probing (BOP), suppuration (SUP), recession (REC), cytokines (IL-1β, IL-1RA, IL-6, IL-8, IL-12, IP10, PDGF-BB, TNF-α, VEGF), and patient-reported outcomes (PROs) were evaluated at 3, 6, 9, and 12 months.

RESULTS

RDF at the deepest site amounted 2.7 ± 1.3 mm in TG and 1.4 ± 1.2 mm in CG (p <.0001). PPD was reduced by 1.9 mm in TG and 2.3 mm in CG (p = .5783). There were no significant differences between groups regarding reductions of BOP, SUP, REC, cytokines levels, or oral health impact profile (OHIP)-14 scores at 12 months. Successful treatment (RDF ≥ 1.0 mm, PPD ≤5 mm, ≤1/4 site with BOP grade 1, no SUP) was identified in 32% in TG and 21% in CG.

CONCLUSIONS

DBBM and NBCM resulted in significantly more RDF than debridement alone. No difference was found in any clinical parameters or PROs between the groups. ClinicalTrials.gov Identifier: NCT02375750.

Evaluation of clinical performance and survival rate of Straumann dental implants in Saudi Population based on cross-sectional study

Risk indicators of peri-implantitis is still contradictory and somehow unclear in present literature therefore efforts should be done for better understanding of the exact etiology of peri-implant disease progression. The present study aimed to assess risk indicators associated with peri-implantitis by observing the changes in several periodontal parameters after implant placement. This cross-sectional study included 213 female and 271 male patients aged 26–87 years, who received 484 titanium implants (Straumann, Switzerland) at King Saud University’s Dental College, Saudi Arabia. Patients were called for dental visits. During these visits; full clinical and radiographic assessment of implants were done. The periodontal pocket depth (PPD) was greater around implants placed at grafted sites than non-grafted sites and around bone-level implants than tissue-level implants. The plaque index (PI) was associated with poor oral hygiene. There was a strong association between graft (yes/no) and bleeding on probing (BOP). Patients with good oral hygiene showed high radiographic bone stability. Keratinized tissue width < 2 mm was associated with a higher PPD, higher PI, higher BOP, more edematous gingiva, and more exposed implant threads on radiography. In patients receiving implants, poor oral hygiene status and inadequate keratinized tissue level can be proposed as risk indicators for developing periimplantitis due to strong association found between them and developments of peri-implantitis.

Biomarker levels in peri-implant crevicular fluid of healthy implants, untreated and non-surgically treated implants with peri-implantitis

AIM

To compare biomarker levels in peri-implant crevicular fluid (PICF) of healthy implants with levels in PICF of implants with peri-implantitis (before and after non-surgical treatment).

MATERIALS AND METHODS

Samples were taken from 20 healthy implants (n = 17 patients) and from 20 implants with peri-implantitis (n = 19 patients) before and 3 months after non-surgical treatment using the Airflow Master Piezon^® (EMS). A Luminex™ assay was used to evaluate pro-inflammatory and anti-inflammatory cytokines IL-1β, TNF-α, IL-6 and G-CSF, collagen degradation enzyme MMP-8, chemokines MCP-1 & MIP-1α/CCL3, bone markers OPG and sRANKL and interferon-γ. Clinical and radiographical characteristics were assessed. A Mann-Whitney U and Wilcoxon signed-rank test analysed between- and within-group differences.

RESULTS

IL-1β and MMP-8 levels were found significantly elevated in implants with peri-implantitis (p = .007; p = <.001, respectively). No difference in levels of TNF-α, IL-6, MCP-1 and MIP-1α/CCL3, OPG and G-CSF between healthy and diseased implants was found. Levels of sRANKL and INF-γ were under the level of detection. None of the biomarker levels improved after non-surgical therapy, and levels of IL-1β and MMP-8 remained high.

CONCLUSION

Implants diagnosed with peri-implantitis have higher levels of IL-1β and MMP-8 in PICF compared to healthy implants. Non-surgical therapy did not influence the inflammatory immune response.

Immunological Aspects of Dental Implant Rejection

Nowadays, dental implants are a prominent therapeutic approach among dentists for replacing missing teeth. Failure in dental implants is a severe challenge recently. The factors which lead to dental implant failure are known. These factors can be categorized into different groups. In this article, we discussed the immunological aspects of implant failure as one of these groups. Cytokines and immune cells have extensive and various functions in peri-implantitis. The equilibrium between pro and anti-inflammatory cytokines and cells, which involve in this orchestra, has a crucial role in implant prognosis. In conclusion, immune cells, especially macrophages and dendritic cells, almost increased in the patients with implant failure. Also, proinflammatory cytokines were proposed as diagnostic factors according to their higher levels in dental implant rejection.

Biosensor and Lab-on-a-chip Biomarker-identifying Technologies for Oral and Periodontal Diseases

Periodontitis is a complex multifactorial disease that can lead to destruction of tooth supporting tissues and subsequent tooth loss. The most recent global burden of disease studies highlight that severe periodontitis is one of the most prevalent chronic inflammatory conditions affecting humans. Periodontitis risk is attributed to genetics, host-microbiome and environmental factors. Empirical diagnostic and prognostic systems have yet to be validated in the field of periodontics. Early diagnosis and intervention prevents periodontitis progression in most patients. Increased susceptibility and suboptimal control of modifiable risk factors can result in poor response to therapy, and relapse. The chronic immune-inflammatory response to microbial biofilms at the tooth or dental implant surface is associated with systemic conditions such as cardiovascular disease, diabetes or gastrointestinal diseases. Oral fluid-based biomarkers have demonstrated easy accessibility and potential as diagnostics for oral and systemic diseases, including the identification of SARS-CoV-2 in saliva. Advances in biotechnology have led to innovations in lab-on-a-chip and biosensors to interface with oral-based biomarker assessment. This review highlights new developments in oral biomarker discovery and their validation for clinical application to advance precision oral medicine through improved diagnosis, prognosis and patient stratification. Their potential to improve clinical outcomes of periodontitis and associated chronic conditions will benefit the dental and overall public health.

Laser-assisted regenerative surgical therapy for peri-implantitis: A randomized controlled clinical trial

BACKGROUND

Different surgical approaches have been proposed to treat peri-implantitis defects with limited effectiveness and predictability. Laser has been proposed as an effective tool to assist in bacterial decontamination and modulating peri-implant tissue inflammation. The aim of this pilot clinical trial was to evaluate the adjunctive benefits of Er:YAG laser irradiation for regenerative surgical therapy of peri-implantitis-associated osseous defects.

METHODS

Twenty-four patients diagnosed with peri-implantitis with a radiographic infrabony defect were randomized into two groups. Both test and control groups received the following treatment: open flap mechanical debridement, supracrestal implantoplasty, bone grafting using a mixture of human allograft with demineralized bone matrix human allograft putty, and then covered with acellular dermal matrix membrane. The only difference in the test group was the adjunctive use of Er:YAG laser to modulate and remove inflammatory tissue as well as to decontaminate the implant surface. Clinical assessments, including pocket depth (PD), clinical attachment level (CAL), and gingival index (GI) were performed by calibrated masked examiners for up to 6 months following surgery. Standardized radiographs were also taken to evaluate linear bone gain and defect bone fill. Student t-tests were used to analyze those clinical parameters.

RESULTS

Both groups showed significant reductions in PD, GI, and CAL gain overtime. The test group demonstrated significantly higher PD reductions at the site level compared to the control group (2.65 ± 2.14 versus 1.85 ± 1.71 mm; test versus control, P = 0.014). There were no statistical differences found in CAL gain (1.90 ± 2.28 versus 1.47 ± 1.76 mm; test versus control), GI reduction (-1.14 ± 1.15 versus -1.04 ± 0.89; test versus control), radiographic linear bone gain (1.27 ± 1.14 versus 1.08 ± 1.04 mm; test versus control) or proportional defect size reduction (- 24.46 ± 19.00% versus -15.19 ± 23.56%; test versus control). There was a positive trend for test patients on PD reduction and CAL gain found in narrow infrabony defects. Major membrane exposure negatively impaired the overall treatment outcome of CAL gain (2.47 ± 1.84 versus 1.03 ± 1.48 mm; no/minor versus major exposure, P = 0.051) and PD reduction in the test group (-3.63 ± 2.11 versus -1.66 ± 1.26 mm, P = 0.049).

CONCLUSION

This pilot study indicated using laser irradiation during peri-implantitis regenerative therapy may aid in better probing PD reduction. Nonetheless, a larger sample size and longer follow-up is needed to confirm if Er:YAG laser irradiation provides additional clinical benefits for peri-implantitis regenerative therapy (Clinicaltrials.gov: NCT03127228).

Suppuration as diagnostic criterium of peri-implantitis

BACKGROUND

Suppuration (SUP) as a diagnostic parameter for monitoring dental implants is not yet well understood. The retrospective clinical and radiographic study was therefore performed to investigate the patient, implant, and site characteristics among individuals exhibiting SUP.

METHODS

Demographic characteristics and clinical parameters were recorded. Radiographic features were analyzed using cone-beam computed tomography. Peri-implantitis was defined based on the consensus report of Workgroup 4 of the 2017 World Workshop on the Classification of Periodontal and Peri-Implant Diseases and Conditions: probing depth (PD) ≥6 mm, presence of bleeding and/or SUP on gentle probing, and radiographic marginal bone loss (MBL) ≥3 mm. SUP was graded according to profuseness (dot versus line/drop) and time after probing (≥15 seconds versus <15 seconds after probing versus spontaneous). Simple binary logistic regression models were estimated using generalized estimation equations to explain the probability of SUP based on demographic, clinical, and radiographic variables.

RESULTS

A total of 111 eligible patients (n_implants  = 501) were assessed. Of them, 57 (n_implants  = 334) were diagnosed with peri-implantitis according to the established case definition, and of these individuals, 31 (n_implants  = 96) presented SUP. Therefore, the prevalence of SUP was 27.92% in the total sample size and 54.38% in peri-implantitis patients. Overall, 28.74% implants displayed SUP within patients with peri-implantitis. SUP was more frequently found at buccal sites (51%) and proved less prevalent at mesio-lingual sites (16.7%). Defect morphology (OR = 6.59; P = 0.004), PD (OR = 1.63; P = 0.024), and MBL (OR = 1.35; P = 0.010) were significantly associated with the presence of SUP. Likewise, defect morphology (P = 0.02), PD (P = 0.003), and MBL (P = 0.01) were significantly correlated with the grade of SUP.

CONCLUSION

The presence and grade of SUP are associated with peri-implant bone loss, probing depth, and defect morphology in patients with peri-implantitis.

Soft tissue healing around platform-switching and platform-matching single implants: A randomized clinical trial

BACKGROUND

Implants with platform-switching (PS) design have been demonstrated to reduce marginal bone loss. However, the influence on peri-implant soft tissue healing is unclear. This study was designed to investigate its effect on peri-implant soft tissue healing after implant uncovery.

METHODS

Non-smokers needing two implants in different quadrants were recruited in this study. For each individual, one PS and one platform-matching (PM) implants were placed using two-stage protocol. Following 2 to 8 months of healing, all implants were uncovered and connected to the corresponding healing abutments. Clinical measurements and peri-implant crevicular fluid (PICF) were taken at 1-, 2-, 4-, and 6-week after 2nd stage surgery. The cytokine concentrations in PICF were analyzed. Peri-implant mucosa (1 × 2 × 2 mm) was harvested around the healing abutment for the analysis of gene expression at uncovery and 6-week post-uncovery.

RESULTS

Eighteen participants (nine males; 51.7 ± 14.9 years) were recruited. Compared to PM, PS showed significantly lower probing depth (PD) at 1- and 2-week as well as modified sulcus bleeding index (mSBI) at 1-, 4-, and 6-week (P < 0.05). Over time, a decrease in osteoprotegerin and interleukin-1β concentrations in PICF along with an increase in receptor activator of unclear factor kappa-B ligand, periostin, and peroxidasin gene expressions in peri-implant mucosa were noted within both groups (P < 0.05) without significant intergroup differences.

CONCLUSION

Within the limits, implants with PS design rendered significant benefits over PM design in PD and mSBI reduction during a 6-week healing. However, molecular changes within PICF and peri-implant mucosa as a response to PM and PS appear negligible.

The Microbiome of Peri-Implantitis: A Systematic Review and Meta-Analysis

This review aimed to systematically compare microbial profiles of peri-implantitis to those of periodontitis and healthy implants. Therefore, an electronic search in five databases was conducted. For inclusion, studies assessing the microbiome of peri-implantitis in otherwise healthy patients were considered. Literature was assessed for consistent evidence of exclusive or predominant peri-implantitis microbiota. Of 158 potentially eligible articles, data of 64 studies on 3730 samples from peri-implant sites were included in this study. Different assessment methods were described in the studies, namely bacterial culture, PCR-based assessment, hybridization techniques, pyrosequencing, and transcriptomic analyses. After analysis of 13 selected culture-dependent studies, no microbial species were found to be specific for peri-implantitis. After assessment of 28 studies using PCR-based methods and a meta-analysis on 19 studies, a higher prevalence of Aggregatibacter actinomycetemcomitans and Prevotella intermedia (log-odds ratio 4.04 and 2.28, respectively) was detected in peri-implantitis biofilms compared with healthy implants. Actinomyces spp., Porphyromonas spp. and Rothia spp. were found in all five pyrosequencing studies in healthy-, periodontitis-, and peri-implantitis samples. In conclusion, the body of evidence does not show a consistent specific profile. Future studies should focus on the assessment of sites with different diagnosis for the same patient, and investigate the complex host-biofilm interaction.

The effects of decontamination methods of dental implant surface on cytokine expression analysis in the reconstructive surgical treatment of peri-implantitis

The aim of this trial was to analyze the effect of implant surface decontamination procedures combined with reconstructive surgical treatment (RST) of peri-implantitis on gene expression levels of selected biomarkers in peri-implant crevicular fluid (PICF). Forty patients diagnosed with peri-implantitis were treated with RST + decontamination of the implant surface using sterile saline and ozone therapy (ozone group) or sterile saline alone (control group). The gene expression levels of interleukin (IL)-6, IL-8, IL-17, vascular endothelial growth factor (VEGF), sclerostin (SOST) and osteoprotegerin (OPG) were evaluated by qPCR analysis at baseline and 6-month follow-up. Changes in cytokine mRNA expression levels were analyzed and compared with clinical/radiographic parameters. Both decontamination methods lead to the downregulations of the selected gene expressions. Ozone group showed significantly higher clinical attachment level (CAL) and radiographic defect fill (DF) values at 6 months compared to the control group (p = 0.026 and p = 0.011). The downregulation of SOST levels was significantly associated with probing depth reduction and radiographic DF (p < 0.05). Implant surface decontamination procedures applied with the RST contribute to a notable reduction in immuno-inflammatory response. The additional use of ozone therapy could have favorable effects in anti-infective regimens of peri-implantitis therapy. SOST, which was found to have significant relationship with both clinical and radiographic outcomes, could be a valuable indicator for the progression of peri-implantitis and may aid the development of new therapeutic strategies for bone gain in the RST of peri-implantitis.

Peri-Implantitis Diagnosis and Prognosis Using Biomarkers in Peri-Implant Crevicular Fluid: A Narrative Review

Dental implant diseases, peri-implantitis (PI) and peri-implant mucositis (PIM), have shown wide prevalence in recent studies. Despite the prevalence, diagnosing peri-implant disease (PID) remains challenging as common diagnostic methods of periodontal probing and radiographs may be inaccurate. These methods only document pre-existing destruction rather than current disease activity. Furthermore, there is no current model to predict the progression of PID. Though a predictive model is lacking, biomarkers may offer some potential. Biomarkers are commonly used in medicine to objectively determine disease state, or responses to a therapeutic intervention. Gingival crevicular fluid (GCF) biomarkers have moderate diagnostic validity in periodontitis. Biomarkers in peri-implant crevicular fluid (PICF) also show promising results in regard to their diagnostic and prognostic value. The aim of this review is to summarize the current knowledge of PICF biomarkers in the diagnosis of PID and evaluate their validity to predict disease progression. This review found that PICF studies utilize different methods of sampling and interpretation with varying validity (sensitivity and specificity). A number of promising diagnostic techniques were identified. Commercially available chair-side tests for MMP-8 to diagnose periodontal disease and PID activity are now available. Future directions include proteomics and metabolomics for accurate, site-specific diagnosis and prediction of PID progression. Although more research is needed, this review concludes that the assessment of proinflammatory cytokines (IL-1β, TNFα, MMP-8) in the PICF may be of value to diagnose PI and PIM but current research remains insufficient to indicate whether biomarkers predict peri-implant disease progression.

Mangiferin alleviates experimental peri-implantitis via suppressing interleukin-6 production and Toll-like receptor 2 signaling pathway

BACKGROUND

TLR2 (Toll-like receptor 2) signaling and its downstream proinflammatory cytokines are considered to be important in the progression of peri-implantitis. A natural medicine, mangiferin has exhibited modulatory effect on TLR2 signaling and anti-inflammatory effects on different diseases. The objective of the present study is to investigate the effect of mangiferin on peri-implantitis and the potential mechanisms by administering this drug to an experimental peri-implantitis mouse model.

METHODS

Maxillary left first, second, and third molars of mice were extracted, and dental implants were placed in the region of the maxillary left second molars. Then, peri-implantitis was induced by tying ligatures around implants, and mangiferin was given orally to the mice. After 6-week mangiferin treatment, bone loss around the implants was detected using micro-computerized tomography (micro-CT). Alveolar bone and inflammatory infiltrate in peri-implant tissues were examined using hematoxylin and eosin (H&E) staining. Production of interleukin-6 (IL6), a TLR2 downstream proinflammatory cytokine, in the tissue surrounding implants was measured using quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR) analysis. IL6 protein expression and TLR2 signaling pathway activation in peri-implant tissues were detected using western blot analysis.

RESULTS

Micro-CT demonstrated reduced bone loss in peri-implantitis upon mangiferin administration. Additionally, H&E staining showed more alveolar bone and less inflammatory infiltrate in peri-implant tissues after mangiferin application. Moreover, qRT-PCR analysis demonstrated lower levels of IL6 gene expression, and western blot analysis showed decreased protein expression of IL6 and TLR2, and suppressed phosphorylation of TLR2 downstream nuclear factor-κB, p38 mitogen-activated protein kinase, and c-Jun N-terminal kinase after mangiferin treatment.

CONCLUSIONS

These results suggest the suppressive effect of mangiferin on bone damage and inflammatory infiltrate in peri-implantitis. These therapeutic effects may be associated with inhibited IL6 production and reduced TLR2 signaling activation in peri-implant tissues.

Comparison of peri-implant soft tissues in submerged versus transmucosal healing: A split mouth prospective immunohistochemical study

OBJECTIVE

The present split-mouth prospective study involves an immunohistochemical evaluation of peri-implant soft tissue healing after the osseointegration period, comparing submerged and transmucosal approaches using two-piece implant systems. The null hypothesis was that both surgical procedures elicit a similar immune response of the peri-implant soft tissues.

DESIGN

Thirty-one healthy patients were included in this study, in which two implants were placed in the right and left maxillary pre-molar regions. A total of 62 dental implants were analyzed, establishing a control side with 31 submerged implants, and a study side with 31 exposed implants bearing healing abutments. After a three-month healing period, a soft tissue biopsy was collected and prepared for immunohistochemical analysis of the proportions of different lymphocyte subpopulations.

RESULTS

The comparative analysis between the submerged and transmucosal approaches failed to identify statistically significant differences in CD19+ B cells, CD4+ T cells, CD8+ T cells, CD25+ T cells or γd T cells. However, significant differences in NK lymphocytes (p = 0.012) were recorded with the submerged surgical procedure.

CONCLUSIONS

Peri-implant soft tissue immune response with submerged or transmucosal healing protocols demonstrated comparable outcomes after the osseointegration period. There is sufficient evidence that the null hypothesis of no difference cannot be rejected. To the best of our knowledge, this is the first study of its kind. Further research is therefore needed to further clarify the role of these lymphocyte subpopulations in peri-implant soft tissues.

Leptotrichia species in human infections II

Leptotrichia species are non-motile facultative anaerobic/anaerobic bacteria that are found mostly in the oral cavity and some other parts of the human body, in animals, and even in ocean sediments. Valid species include L. buccalis, L. goodfellowii, L. hofstadii, L. honkongensis, L. shahii, L. trevisanii, and L. wadei. Some species require serum or blood for growth. All species ferment carbohydrates and produce lactic acid that may be involved with tooth decay. Acting as opportunistic pathogens, they are involved in a variety of diseases, and have been isolated from immunocompromised but also immunocompetent individuals. Mucositis, oral lesions, wounds, and abscesses may predispose to Leptotrichia septicemia. Because identification of Leptotrichia species by phenotypic features occasionally lead to misidentification, genetic techniques such as 16S rRNA gene sequencing is recommended. Early diagnosis and treatment of leptotrichia infections is important for positive outcomes. Over the last years, Leptotrichia species have been associated with several changes in taxonomy and new associations with clinical diseases. Such changes are reported in this updated review.