Single-cell sequencing identifies inflammation-promoting fibroblast-neutrophil interaction in peri-implantitis.

AIM: To reveal the cellular composition and molecular environment of the periodontal and peri-implant inflammatory infiltrates through a single-cell sequencing technique, which may explain the pathological difference between these two diseases. A special focus was placed on the phenotypes and potential roles of neutrophils and fibroblasts in peri-implant/periodontal tissue immunity. MATERIALS AND METHODS: High-throughput single-cell transcriptomic profiling of peri-implant tissues from patients with peri-implantitis as well as periodontal tissues from patients with periodontitis and healthy donors was performed. Immunofluorescence analysis was carried out to further validate the identified cell subtypes and their involvement in peri-implantitis and periodontitis. RESULTS: Based on our single-cell resolution analysis, a quantified proportional increase of neutrophil (Neu) subtypes was shown in peri-implantitis. Among these, a predominance of Neutro_CXCR2 was revealed. We also found the involvement of inflammation-promoting fibroblasts as well as a predominance of CXCL8+ fibroblast-CXCR2+ neutrophil interaction in peri-implantitis. CONCLUSIONS: Our study indicated that the predominance of CXCL8+ fibroblast-CXCR2+ neutrophil interaction might underline the enhanced host response in peri-implantitis compared with periodontitis. This information offers a molecular basis by which fibroblast and neutrophil subtypes might be diagnostically and therapeutically targeted in peri-implantitis.

Long-term clinical outcomes of short implant (6mm) in relation to Implant Disease Risk Assessment (IDRA).

AIM: To evaluate the long-term survival of short implants and to investigate the association of the Implant Disease Risk Assessment (IDRA) with the occurrence of biological complications. MATERIAL AND METHODS: This study was designed as a cohort study with a median follow-up of 10.0 years. Patients who had received 6-mm implants were reviewed and assigned into low-, moderate-, and high-risk groups (Group L, M, and H) based on the IDRA tool. The implant survival, biological complications, soft tissue condition, hardware complications, and marginal bone loss (MBL) were evaluated. Kaplan-Meier curves and Cox regression were performed for survival analysis. RESULTS: A hundred and ten patients were included. The overall cumulative survival rate was 90.9% (L:100.0%, M: 93.3%, and H: 80.6%). A higher risk profile was significantly associated with a decreased implant survival (hazard ratio: 4.11, 95% CI: 1.17-14.36, p < .05). Higher risk profile (hazard ratio: 2.63, 95% CI: 1.32-5.25, p < .05) was a potential risk factor for biological complications. At follow-up, significant differences in bleeding index, modified plaque index, and peri-implant probing depth were found among groups (p < .01). No significant difference was found in MBL. CONCLUSION: Acceptable long-term clinical outcomes could be achieved after 10 years for short implants. Despite a statistically nonsignificant difference in MBL, patients with a high-risk profile of IDRA seem to be at greater risk of implant loss and biological complications.

Single-Cell RNA Sequencing Identifies New Inflammation-Promoting Cell Subsets in Asian Patients With Chronic Periodontitis.

Periodontitis is a highly prevalent chronic inflammatory disease leading to periodontal tissue breakdown and subsequent tooth loss, in which excessive host immune response accounts for most of the tissue damage and disease progression. Despite of the imperative need to develop host modulation therapy, the inflammatory responses and cell population dynamics which are finely tuned by the pathological microenvironment in periodontitis remained unclear. To investigate the local microenvironment of the inflammatory response in periodontitis, 10 periodontitis patients and 10 healthy volunteers were involved in this study. Single-cell transcriptomic profilings of gingival tissues from two patients and two healthy donors were performed. Histology, immunohistochemistry, and flow cytometry analysis were performed to further validate the identified cell subtypes and their involvement in periodontitis. Based on our single-cell resolution analysis, we identified HLA-DR-expressing endothelial cells and CXCL13+ fibroblasts which are highly associated with immune regulation. We also revealed the involvement of the proinflammatory NLRP3+ macrophages in periodontitis. We further showed the increased cell-cell communication between macrophage and T/B cells in the inflammatory periodontal tissues. Our data generated an intriguing catalog of cell types and interaction networks in the human gingiva and identified new inflammation-promoting cell subtypes involved in chronic periodontitis, which will be helpful in advancing host modulation therapy.

Long-term outcomes of osteotome sinus floor elevation with or without bone grafting: The 10-year results of a randomized controlled trial.

AIMS: To assess the long-term clinical and radiographic results of implants placed using osteotome sinus floor elevation (OSFE) with or without bone grafting. MATERIALS AND METHODS: Forty-five patients were randomly assigned into two groups: Group 1 (OSFE with deproteinized bovine bone mineral) and Group 2 (OSFE without grafting). The patients were recalled at 1, 3, 5 and 10 years after surgery. The implant survival, endo-sinus bone gain (ESBG), marginal bone loss (MBL), peri-implant bone height (PBH, distance from the most coronal level to the most apical level of bone-to-implant contact), prosthesis survival and hardware complications, and peri-implant soft tissue conditions were assessed. RESULTS: Forty patients attended the 10-year examination. Mean residual bone height was 4.58 ± 1.28 mm. The 10-year cumulative survival rate was 90.7% for Group 1 and 95.0% for Group 2. The PBH was 5.89 ± 1.24 mm for Group 1 and 5.74 ± 1.43 mm for Group 2 at 10 years. The ESBG of both groups remained stable after 3 years. Two-thirds of the implants were free of hardware complications. No significant differences in MBL and peri-implant tissue parameters were found. CONCLUSION: OSFE with or without grafting both yielded predictable clinical outcomes with similar PBH (ClinicalTrials.gov. NCT01619956).

The responses of human gingival fibroblasts to magnesium-doped titanium.

The titanium (Ti) implant is widely used in implant dentistry; yet peri-implantitis has always been one of the most common and serious complications. Here, we demonstrated that magnesium-doping would be an effective way of enhancing the integration between implant surfaces and gingival tissues, which is critical to peri-implant health. The magnesium (2.76-6.35 at %) was immobilized onto the titanium substrate by a magnesium plasma immersion ion implantation (Mg-PIII) technique. Mg-PIII treatments did not alter surface topographies of the original titanium substrate but improved its hydrophilicity. The in vitro study including cell viability, adhesion, proliferation, migration, and real-time polymerase chain reaction assays disclosed improved adhesion, proliferation, migration, and extracellular matrix remodeling abilities of human gingival fibroblasts (HGFs) on the magnesium-doped titanium. The results of western blot suggested that the Mg-modified titanium induced the phosphorylation of AKT through the activation of PI3K. Our results revealed that magnesium-doping would potentially enhance soft tissue sealings by promoting cellular functions of HGFs in a dose-dependent manner, boding well for its applications on surfaces of implant necks in early peri-implant soft tissue integrations.

Endo-sinus bone formation after transalveolar sinus floor elevation without grafting with simultaneous implant placement: Histological and histomorphometric assessment in a dog model.

AIM: To evaluate endo-sinus new bone formation and implant osseointegration after transalveolar sinus floor elevation (TSFE) and simultaneous implant placement without any grafting materials and to investigate the influence of implant surface modification on bone healing process under this circumstance. MATERIALS AND METHODS: Transalveolar sinus floor elevation and simultaneous implant placement were conducted bilaterally on 12 Labrador dogs. No grafting materials were used during surgery. Implants with two different surfaces (SLA and SLActive) were placed in a split-mouth design. The animals were sacrificed 4, 8 and 24 weeks after surgery for histological and histomorphometric assessments. Bone-to-implant contact (BIC%), alveolar bone height (ABH) and the percentages of mineralized bone (MB%) in the area of interest were analysed. The probing depth (PD) and bleeding on probing (BOP) were also assessed to describe peri-implant health conditions. RESULTS: Sprouts of new bone in direct contact with implant surface were seen in the elevated area at every time point. Newly formed woven bone under sinus membrane was visible. SLActive implants exhibited favourable results compared with SLA implants regarding ABH at 4 weeks and BIC% at 4 and 8 weeks. Sites with BOP positive could be observed in both groups at any time point. No newly formed bone can be found on the implant apex with either SLA or SLActive surfaces at any time point. CONCLUSIONS: Spontaneous new bone formation from the parent bone walls could be observed after TFE without any grafting materials. No clear evidence of bone formation from the Schneiderian membrane could be found. Even though there were trends for quicker bone response of SLActive implants, this study failed to show the absolute advantage of SLActive in achieving endo-sinus bone formation.

Hardware complications and failure of three-unit zirconia-based and porcelain-fused-metal implant-supported fixed dental prostheses: a retrospective cohort study with up to 8 years.

OBJECTIVE: The aim of the present study was to assess the hardware complications and survival of three-unit implant-supported zirconia-based fixed dental prostheses (IZ) and implant-supported porcelain-fused-metal fixed dental prostheses (IP). MATERIAL AND METHODS: The study is a retrospective cohort study with up to 8 years (mean 4.8 years) follow-up. Patients with conventional three-unit implant-supported fixed dental prostheses (without cantilever) in posterior area were reviewed. Hardware complications and survival rate were evaluated. Chi-Square test was used to test the difference between IZ and IP groups. RESULTS: Two hundred and thirty-seven patents (IZ : 112, IP : 125) with 279 three-unit restorations (IZ : 127, IP : 152) participated in the study. The overall survival rate was 95.3% in IZ group and 94.7% in IP group at implant-level and 94.6% in IZ group and 94.4% in IP group at subject-level. Veneer chipping was the most frequently seen complication (20.1%). Significant higher minor veneer chipping rate (Grade 1) was found in IZ group (P = 0.04). No significant difference of veneer chipping rate (Grade 2 and Grade 3) was found between the two groups. The overall hardware complication rates of IZ were significantly higher than IP (33.07% and 18.42%, P = 0.01). CONCLUSION: High survival rate of zirconia-base and Porcelain-fused-to-metal (PFM) restorations can be achieved with up to 8 years follow-up. The zirconia-based restorations need more polishing procedures, maintenance, and professional care than PFM restorations. The number of implants supporting a fixed dental prosthesis did not influence the implant survival and hardware complications. Well-designed studies with high evidence level are still needed to further explore the hardware complications and clinical survival of IZ and IP.

Clinical Investigation and Patient Satisfaction of Short Implants Versus Longer Implants with Osteotome Sinus Floor Elevation in Atrophic Posterior Maxillae: A Pilot Randomized Trial.

PURPOSE: The aim of the study was to evaluate the clinical parameters and patient satisfaction of the treatments with short implants compared to longer implants with osteotome sinus floor elevation (OSFE) in atrophic posterior maxillae. MATERIALS AND METHOD: The patient data were retrieved from an ongoing randomized controlled trial (NCT02350075). Patients were randomly allocated into three groups: (group1: short-6 mm implant, group 2: short-8-mm implant with OSFE, group 3: standard-10 mm implant with OSFE). Early implant failure, complications, implant stability quotient (ISQ) and patient satisfaction by means of visual analogue scale (VAS) were evaluated. ANOVA analysis was performed for the data comparison. RESULTS: Fifty-six patients were enrolled in the present study. No implant loss was found by the end of the restoration placement. No significant difference of ISQ values was found among three groups at the time of implant surgery and impression taking (p = .67 and.54, respectively). VAS values regarding intraoperative vibratory sense in group 1 were significantly higher than those in group 3 (p = .01). CONCLUSION: All three treatments were safe in atrophic posterior maxilla (6 mm ≤ residual bone height < 8 mm). Patients were satisfied with all three treatments, while the malleting during the osteotome procedure could make patients feel uncomfortable.

Resonance frequency analysis of implants placed with osteotome sinus floor elevation in posterior maxillae.

OBJECTIVES: To test the reliability and validity of implant stability quotient (ISQ) values used for assessment of the condition of bone-to-implant interface in the osteotome sinus floor elevation (OSFE) model and to evaluate the influence of residual bone height (RBH) on ISQ values. MATERIAL AND METHODS: Forty-six Straumann(®) tissue-level SLA implants (Φ4.8 mm*8 mm, wide neck, standard plus) placed in 39 patients applying OSFE without grafting were included in the study. Patients were assigned to three groups based on the RBH with one implant per patient randomly chosen: (1) 2 ≤ RBH < 4 mm (n = 14); (2) 4 ≤ RBH < 6 mm (n = 15); (3) 6 ≤ RBH < 8 mm (n = 10). ISQ values were determined with Osstell ISQ(®) at 0, 2, 4, 8, 12, 16, and 20 weeks postoperation. The reliability of RFA measurements was tested by the degree of dispersion of ISQ values at each time point, and the validity was tested by linear correlation between ISQ and RBH. ISQ values were then compared among groups at all observed time points. RESULTS: The implants achieved a mean ISQ value of 63.6 immediately after surgery and reached a higher ISQ level of 70 after 20 weeks with a dip at 4 weeks. A higher degree of dispersion of ISQ values was observed immediately after surgery compared to the other time points. No significant correlations were found between RBH and ISQ values and no significant difference in ISQ values among groups at all the time points. CONCLUSION: Within the limits of the study, it may be implied that ISQ values are not able to assess the condition of bone-to-implant interface and the role of single RFA measurement in determining loading protocol is questionable.

Transalveolar sinus floor elevation using osteotomes without grafting in severely atrophic maxilla: a 5-year prospective study.

OBJECTIVE: The aim of this study was to assess the clinical success of dental implants placed in severely atrophic maxilla (residual bone height ≤4 mm) using transalveolar sinus floor elevation (TSFE) without grafting. Furthermore, the implant stability during the healing period was also evaluated. MATERIALS AND METHODS: Twenty five generally healthy patients with 37 Straumann(®) Standard Plus SLA implants were included in the study. After a modified Summers TSFE without grafting was performed, the smooth collar was embedded 0.5-1 mm beneath the cortical bone level. Follow-ups were conducted at 12, 36, and 60 months after crown placement. Implant survival rate, resonance frequency analysis (RFA), and clinical and radiographic parameters were evaluated. RESULTS: At 5-year follow-up, 35 implants fulfilled the survival criteria, representing a 5-year cumulative survival rate of 94.6% at implant level and 92% at subject level. The mean value of implant stability quotient (ISQ) ranged from 67.8 to 72.8, and the lowest values were reached at 4 weeks. No significant difference was found with the passage of time in modified plaque index (P = 0.92), pocket probing depth (P = 0.34), and modified bleeding index (P = 0.4). The average residual bone height was 2.81 mm (SD: 0.74 mm) in this study. The average crestal bone loss (CBL) significantly increased from 0.83 mm at 1-year examination to 1.47 mm at 3-year examination (P < 0.001). The average CBL remained stable at years 3 and 5 (1.47 vs. 1.54 mm, P = 0.083). CONCLUSION: According to the current evidence, it is feasible to place cylindrical implants in severely atrophic maxilla. High survival rate could be achieved following TSFE without grafting at least within 5-year follow-up.

N-acetyl cysteine protects human oral keratinocytes from Bis-GMA-induced apoptosis and cell cycle arrest by inhibiting reactive oxygen species-mediated mitochondrial dysfunction and the PI3K/Akt pathway.

Bisphenol-A-glycidyl methacrylate (Bis-GMA) released from dental resin materials causes various toxic effects on gingival epithelium. Thus the underlying mechanisms of its cytotoxicity should be elucidated for safety use. One potential cause of cell damage is the generation of reactive oxygen species (ROS) beyond the capacity of a balanced redox regulation. In this study, we found that exposure of human oral keratinocytes (HOKs) to Bis-GMA caused apoptosis and G1/S cell cycle arrest in parallel with an increased ROS level. Moreover, Bis-GMA induced a depletion of mitochondrial membrane potential, an increase in the Bax/Bcl-2 ratio, an activation of caspase-3 and altered expressions of cell cycle-related proteins (p21, PCNA, cyclinD1). Furthermore, the co-treatment of the ROS scavenger N-acetyl cysteine (NAC) obviously attenuated Bis-GMA-induced toxicity. Here we also evaluated the effects of Bis-GMA on the ROS-related PI3k/Akt pathway. We found that Bis-GMA inhibited the phosphorylation of Akt, whereas the amount of phosphorylated Akt was reverted to the control level in the presence of NAC. Our findings suggested that the toxic effects of Bis-GMA were related to ROS production and the antioxidant NAC effectively reduced Bis-GMA-mediated cytotoxicity.

Osteotome sinus floor elevation with and without grafting: an animal study in Labrador dogs.

AIM: To evaluate implant stability and histological outcomes after osteotome sinus floor elevation (OSFE) procedure, and to compare new bone formation and implant osseointegration with and without grafting. MATERIAL AND METHODS: OSFE with simultaneous implant placement was conducted bilaterally on 6 Labrador dogs. Twenty-four implants were placed. The right side sinus (Group 1) was grafted with biphasic calcium phosphate (BCP), whereas the left side (Group 2) was left without any grafting materials. The animals were euthanized 8 and 24 weeks after surgery for histological and histomorphometric assessment. Bone-to-implant contact (BIC%), alveolar bone height (ABH), bone density (BD) and grafting material density (GMD) were measured. The implant stability (ISQ) was assessed using resonance frequency analysis (RFA) at implant placement and 1, 2, 4, 8, 12, 24 weeks after surgery. RESULTS: Endo-sinus new bone with direct contact to implant surface were observed in two groups at both time points. ABH showed no difference between groups at both time points. BIC% and BD in Group 2 (40.05%, 35.90%) was higher than those in Group 1 (23.30%,25.59%) at 24 weeks. Significant shrinkage of grafting material was seen in Group 1. The GMD in Group 1 at 8 weeks was 24.35%, while it dropped to 19.90% at 24 weeks. The changing pattern of ISQ for both groups were similar. CONCLUSIONS: Spontaneous new bone formation and better bone-to-implant contact were found for OSFE without grafting. The grafting material application during OSFE procedure showed no advantages in histological results.

Osteotome sinus floor elevation with or without grafting: a 3-year randomized controlled clinical trial.

AIMS: To evaluate the clinical and radiographic results of dental implant placed using osteotome sinus floor elevation (OSFE) with and without simultaneous grafting. MATERIALS & METHODS: Forty-five patients were randomly assigned into two groups: Group1: OSFE with deproteinized bovine bone mineral (DBBM) mixed with autogenous bone chips, and Group2: OSFE without grafting. The endo-sinus bone gain (ESBG) was assessed on radiographs at 6, 12, 24, 36 months following surgery as primary outcome measurement. Implant survivals and marginal bone loss (MBL) were assessed as secondary outcome measurements. RESULTS: Twenty-one implants in Group1 and 20 implants in Group2 were analysed. The residual bone height (RBH) was 4.63 ± 1.31 mm in average (4.67 ± 1.18 mm for Group1 and 4.58 ± 1.47 mm for Group2). The 3-year cumulative survival rates of implants were 95.2% for Group1 and 95.0% for Group2. The ESBG in Group1 reduced from 5.66 ± 0.99 mm at 6 months to 3.17 ± 1.95 mm at 36 months, whereas the ESBG in Group2 increased from 2.06 ± 1.01 mm at 6 months to 3.07 ± 1.68 mm at 36 months. The MBL after 3 years was 1.33 ± 0.46 mm in Group1 and 1.38 ± 0.23 mm in Group2. CONCLUSIONS: OSFE and simultaneous implant installation with and without grafting both resulted in predictable results. The application of grafting materials has no significant advantage in terms of clinical success.

The roles of PI3K/Akt signaling pathway in regulating MC3T3-E1 preosteoblast proliferation and differentiation on SLA and SLActive titanium surfaces.

Chemical modification to produce a hydrophilic microrough titanium (Ti) implant surface has been shown to increase osseointegration compared with microrough topography alone. This study aimed to investigate the roles of PI3K/Akt signaling pathway in regulating proliferation and differentiation of osteoblasts in response to surface microroughness and hydrophilicity. Ti disks were manufactured to present different surface morphologies: a smooth pretreatment surface (PT), a rough hydrophobic surface that was sand-blasted, large-grit, acid-etched (SLA), and an SLA surface with the same roughness that was chemically modified to possess high wettability/hydrophilicity (SLActive/modSLA). MC3T3-E1 cells were cultured on these substrates with or without LY294002, a PI3K inhibitor, and their behaviors, including cell viability (MTT colorimetric assay), alkaline phosphatase (ALP) activity, and osteogenic genes expression of osteopontin (OPN) and osteocalcin (OCN) were measured. Western blot was applied to detect the expression of PI3K/Akt signal pathway proteins. The results showed that a decrease in osteoblast proliferation associated with the Ti surfaces (SLActive > SLA > PT) correlated with an increase in activity of the osteogenic differentiation markers ALP. The peak of ALP activity appeared earlier at 7 days for the SLActive surfaces compared with the SLA and PT surfaces. Osteoblast proliferation, as well as the level of p-Akt, was significantly inhibited by LY294002 in all three Ti surfaces. The top value of ALP activity was increased with the inhibition of PI3K/Akt signaling pathway while the time of the peak appeared was not advanced. The expression levels of OPN and OCN were upregulated by the effect of surface roughness and hydrophilicity, which were further enhanced by LY294002. In conclusion, osteogenic responses to SLActive surface were moderately better than the SLA surface and protein expression studies indicated that PI3K/Akt signaling activation may be responsible for this increased osteogenic differentiation. Surface microroughness and hydrophilicity may affect osteoblast functions by targeting osteoblast proliferation and the early stage of osteoblast differentiation through PI3K/Akt signaling pathway.

[Papilla alteration in different gingival biotypes at single implant-supported restoration in anterior maxilla].

PURPOSE: To observe the alteration of the interproximal papilla height after single implant restoration in the anterior maxilla and to assess the influence of gingival biotypes on papilla regeneration. METHODS: Thirty patients with single-tooth implant-supported restorations in the anterior maxilla were assigned to two groups according to labial mucosa thickness. Group A: labial mucosal thickness≥1.5 mm and group B: labial mucosal thickness<1.5 mm. The presence of interproximal papilla as well as the distance between papilla apex and contact point were assessed at crown attachment (baseline) and after 6 months (follow-up).Statistical analysis was performed using SPSS19.0 software package. RESULTS: The 6-month survival rate of implants was 100%. The mean height of interproximal papilla at baseline and follow-up was (1.64±0.97) mm and (3.10±1.39) mm, respectively. A significant improvement in papilla height was found between baseline and follow-up(P<0.05). In group A, the mean distance from papilla apex to the contact point at mesial and distal aspects was (0.15±0.24) mm and (0.23±0.33) mm, respectively, and the presence of interproximal papilla were (97±5)% and (94±8)%, respectively. In group B, the mean distance from papilla apex to the contact point at mesial and distal aspects was (1.94±0.40) mm and (2.10±0.34) mm, respectively, and the presence of interproximal papilla was (53±9)% and (43±14)% respectively. Statistically significant difference was found between the two groups(P<0.05). CONCLUSIONS: The interproximal papilla height around single implant restorations could improve significantly after 6-month follow-up. The interproximal papilla height around single-tooth implants in the anterior maxilla was influenced by gingival biotype. The regenerative potential of thick-gingival biotype was better than that of thin-gingival biotype.

Characterization and preosteoblastic behavior of hydroxyapatite-deposited nanotube surface of titanium prepared by anodization coupled with alternative immersion method.

The modification on the titanium (Ti) implant surface is an effective method to improve the bioactivity of Ti. In this study, a hydroxyapatite (HA)-deposited nanotubular Ti surface was prepared by anodization coupled with an alternative immersion method (AIM). Surface physicochemical characteristics including morphology, microstructure, composition, roughness were evaluated by field-emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), Fourier-transformed infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Preosteoblast cell (MC3T3-E1) behavior on the HA-deposited nanotube surface, including cell morphology, proliferation, alkaline phosphatase (ALP) activity, osteocalcin secretion, and mineralization, were also investigated. The untreated nanotube surface and bare Ti were used as controls. The results showed that synthetic HA crystals could be efficiently grown on/inside the nanotubes after AIM treatment in saturated Ca(OH)(2) and 0.02M (NH(4))(2) HPO(4). The amount of synthetic HA on nanotube layer was dependent on the number of dipping cycles. Significant increases in ALP activity and osteocalcin production on day 7 and 14 and calcium deposition on day 21 (P < 0.05) were observed for HA-deposited nanotubular Ti surface when compared with untreated nanotube layer and bare Ti. However, the cell proliferation rate on HA-deposited nanotube surfaces was slowed down significantly (P < 0.05). All these results indicated that this HA-deposited nanotube surface might have the potential benefit to enhance implant osseointegration. The synthetic HA TiO(2) nanotube loading might be a highly promising path to improve the bioactivity of Ti-based implants.