Saliva biofilm-derived outer membrane vesicles regulate biofilm formation and immune response of oral epithelial cells on titanium surfaces.

OBJECTIVES: While the significant roles of outer membrane vesicles (OMVs) from individual oral bacterial species in bacterial-host interactions are known, the involvement of saliva biofilm-derived OMVs in peri-implant disease pathogenesis remains unclear. This study aimed to investigate the effect of saliva biofilm-derived OMVs on regulating saliva biofilm formation and modulating the immune response of the epithelial cells on titanium surfaces. MATERIALS AND METHODS: Saliva derived biofilms were cultured on tissue culture plates (TCP) for 4 days using pooled saliva from four healthy donors. OMVs secreted from the TCP bound biofilm (referred to as OMVs or healthy saliva biofilm OMVs) were enriched using the size-exclusion chromatography method. We then evaluated the effects of these OMVs on the viability, metabolic activity, and the presence of oral pathogens in saliva biofilm grown on titanium discs for 24 h and 72 h. Furthermore, the impact of OMVs on the mRNA expression and inflammatory cytokines [interleukin (IL)-6, IL-1α, and monocyte chemoattractant protein-1 (MCP-1)] in human oral epithelial cells (OKF6/TERT-2) was investigated using RT-qPCR and enzyme-linked immunosorbent assay (ELISA), respectively. RESULTS: Healthy saliva biofilm OMVs improved the biomass and activity of saliva biofilm cultured on the titanium surfaces, with inhibited Porphyromonas gingivalis and Fusobacterium nucleatum, and enhanced Streptococcus mutans expression. Additionally, OMVs increased pro-inflammatory cytokine IL-6 mRNA and IL-6 cytokine expression in human oral epithelial cells. However, IL-1α and MCP-1 cytokines were inhibited 24-hour post-incubation with OMVs. CONCLUSION: Healthy saliva biofilm derived OMVs regulate the activity and pathogen composition of biofilms formed on titanium, while modulating the secretion of pro-inflammation factors of oral epithelial cells grown on titanium surfaces. CLINICAL RELEVANCE: Healthy saliva biofilm OMVs may regulate the early biofilm formation on abutment surfaces and modulate epithelial cell immune response, which may alter the peri-implant niche and participate in the pathogenesis of peri-implant disease.

Transcriptome analysis of human peri-implant soft tissue and periodontal gingiva: a paired design study.

OBJECTIVES: Limited information is available about the biological characterization of peri-implant soft tissue at the transcriptional level. The aim of this study was to investigate the effect of dental implant on the soft tissue in vivo by using paired samples and compare the differences between peri-implant soft tissue and periodontal gingiva at the transcriptional level. METHODS: Paired peri-implant soft tissue and periodontal gingiva tissue from 6 patients were obtained, and the pooled RNAs were analyzed by deep sequencing. Venn diagram was used to further screen out differentially expressed genes in every pair of samples. Annotation and enrichment analysis was performed. Further verification was done by quantitative real-time PCR. RESULTS: Totally 3549 differentially expressed genes (DEGs) were found between peri-implant and periodontal groups. The Venn diagram further identified 185 DEGs in every pair of samples, of which the enrichment analysis identified significant enrichment for cellular component was associated with external side of plasma membrane, for molecular function was protein binding, for biological process was immune system process, and for KEGG pathway was cytokine-cytokine receptor interaction. Among the DEGs, CST1, SPP1, AQP9, and SFRP2 were verified to be upregulated in peri-implant soft tissue. CONCLUSIONS: Peri-implant soft tissue showed altered expressions of several genes related to the cell-ECM interaction compared to periodontal gingiva. CLINICAL RELEVANCE: Compared to periodontal gingiva, altered cell-ECM interactions in peri-implant may contribute to the susceptibility of peri-implant diseases. At the transcriptional level, periodontal gingiva is generally considered the appropriate control for peri-implantitis, except regarding the cell-ECM interactions.

2-DG Regulates Immune Imbalance on the Titanium Surface after Debridement.

Peri-implantitis requires clinical treatments comprised of mechanical and chemical debridement to remove bacterial biofilms. Bone regeneration on the titanium surface after debridement has been a topical issue of peri-implantitis treatments. Increasing evidence has revealed that the immune microenvironment plays a key role in regulating the bone regeneration process. However, it remains unclear what kind of immune microenvironment the titanium surface induces after debridement. In the study, model titanium surface after debridement was prepared via biofilm induction and mechanical and chemical debridement in vitro. Then, the macrophages and naïve CD4+ T lymphocytes were cultured on the titanium surface after debridement for immune microenvironment evaluation, with the original titanium surface as the control. Next, to regulate the immune microenvironment, 2-DG, a glycolysis inhibitor, was further incorporated to regulate macrophages and CD4+ T lymphocytes at the same time. Surface characterization results showed that the bacterial biofilms were completely removed, while the micro-morphology of titanium surface altered after debridement, and the element composition did not change. Compared with the original titanium disc, titanium surface after debridement can lead to the inflammatory differentiation of macrophages and CD4+ T lymphocytes. The percentage of M1 and Th17 inflammatory cells and the expression of their inflammatory factor genes are upregulated. However, 0.3 mmol of 2-DG can significantly reduce the inflammatory differentiation of both macrophages and CD4+ T lymphocytes and inhibit their expression of inflammatory genes. In conclusion, although bacterial biofilms were removed from titanium surface after debridement, the surface topography changes could still induce immune imbalance and form an inflammatory immune microenvironment. However, this inflammatory immune microenvironment can be effectively reversed by 2-DG in vitro, thus creating an immune microenvironment conducive to osteogenesis, which might provide a new perspective for future therapy of peri-implantitis.

The occurrence of peri-implant mucositis associated with the shift of submucosal microbiome in patients with a history of periodontitis during the first two years.

AIM: To investigate the dynamic changes of peri-implant microbiome in patients with a history of periodontitis and to construct a microbial prediction model. MATERIALS AND METHODS: The prospective study was performed at one month (T1), one year (T2) and two years (T3) after restoration. Clinical examinations [probing depth (PD), bleeding on probing (BOP), suppuration (SUP)], radiographic examinations and sample collection were conducted at three timepoints. Peri-implant sulcular fluid (PISF) was collected and analysed by 16S rRNA gene sequencing. Generalized linear mixed model (GLMM) was used to identify differences. RESULTS: Totally, 168 subjects were assessed for eligibility. Twenty-two patients were recruited in the longitudinal study. Eventually, 67 PISF samples from 24 implants of 12 patients were collected and analysed. Peri-implant microbiome showed increasing diversity and complexity over time. Disease-associated genera Porphyromonas, Tannerella, Treponema and Prevotella dramatically increased from T1 to T3. The prediction model for clinical suppuration at T1 showed a high accuracy of 90%. CONCLUSION: The dysbiosis of peri-implant microbiome increased with time during the two-year observation in patients with a history of periodontitis. Genera of Porphyromonas, Tannerella, Treponema and Prevotella were biomarkers of peri-implant mucositis. Microbiota at the early stage could predict subsequent microbial dysbiosis and clinical suppuration.

Improved accuracy of digital implant impressions with newly designed scan bodies: an in vivo evaluation in beagle dogs.

BACKGROUND: The accuracy of digital impressions for fully edentulous cases is currently insufficient for routinely clinical application. To overcome the challenge, a modified scan body was introduced, which demonstrated satisfactory accuracy in vitro. The aim of this study was to evaluate the accuracy of digital impressions using the modified scan bodies with extensional structure versus scan bodies without extensional structure in mandible with two implants in beagle dogs. METHODS: The unilateral mandibular second premolar to second molar were extracted in four beagle dogs. Twelve weeks later, two implants were placed. Five repeated digital impressions were performed with an intraoral scanner on each dog using each of the two different scan bodies: Group I-scan body without extensional structure (SB); Group II-scan body with extensional structure (SBE). The scans were exported to Standard Tessellation Language (STL) files to serve as test data. The dogs were sacrificed and the dissected mandibles were digitalized with a lab scanner to provide reference data. Linear and angular deviations were calculated in an inspection software for accuracy assessment. Statistical analysis was performed with two-way ANOVA. The level of significance was set at α = 0.05. RESULTS: For trueness assessment, the mean of absolute linear/angular deviations were 119.53 µm/0.75 degrees in Group I and 68.89 µm/0.36 degrees in Group II. SBE was more accurate than SB regarding both linear (p = 0.008) and angular (p = 0.049) deviations. For precision assessment, the mean of absolute linear/angular deviations were 63.01 µm/0.47 degrees in Group I and 38.38 µm/0.24 degrees in Group II. No significant difference was found. CONCLUSIONS: The application of SBE significantly improved the trueness of digital impressions in mandible with two implants compared to SB. No significant difference was found in terms of precision.

Immediate Implant Placement with Buccal Bone Augmentation in the Anterior Maxilla with Thin Buccal Plate: A One-Year Follow-Up Case Series.

PURPOSE: To evaluate the buccal bone thickness of immediate implant placement with buccal bone augmentation in patients with a thin buccal plate in the esthetic zone. MATERIALS AND METHODS: Eighteen consecutive patients requiring a single tooth replacement in the anterior maxillary zone with a thin plate (<1 mm) were included and received immediate implant placement with narrow-diameter implants. Patients received buccal bone augmentation (both internal and external socket bone grafting) with deproteinized bovine bone mineral (DBBM) and an absorbable membrane. The final restoration was delivered after 8 months. Cone-beam CT scans were performed before surgery (CBCT0), immediately after surgery (CBCT1), at final restoration delivery (CBCT2), and at 1-year follow-up after the final restoration (CBCT3) to evaluate the buccal bone thickness and ridge width. A repeated measures ANOVA and Bonferroni correction for multiple comparisons were applied for statistical analysis of changes within different time points (α = 0.05). RESULTS: Fifteen of the 18 enrolled patients were available for analysis at the 1-year follow-up after final restoration. The mean buccal bone thickness at 2 mm apical to the implant-abutment junction (IAJ-2) were 3.59 mm (range: 3.04-4.58 mm), 2.79 mm (range: 2.25-3.78 mm), and 2.52 mm (range: 1.72-3.36 mm), respectively, at CBCT1, CBCT2, and CBCT3. A statistical significance was observed for buccal bone thickness change between CBCT1 and CBCT2 at IAJ-2 (F = 17.948, p = 0.001). The net gains of the ridge width from CBCT0 to CBCT1, CBCT1 to CBCT2, and CBCT2 to CBCT3 were 1.08 mm, -0.94 mm and -0.04 mm at 4 mm apical to the cementum-enamel junction, respectively. No statistical significance was observed for the change in ridge width from CBCT0 to CBCT3 (F = 10.518, p = 1.000). CONCLUSIONS: Simultaneous buccal bone augmentation may maintain a predictable buccal bone thickness for immediate implant placement in the maxillary anterior sites with a thin buccal plate (<1 mm) at 1-year follow-up after final restoration.

Long non-coding RNA and mRNA expression profiles in peri-implantitis vs periodontitis.

BACKGROUND AND OBJECTIVE: Peri-implantitis is a biofilm-mediated infectious disease that results in progressive loss of implant-supporting bone. As compared to its analogue periodontitis, peri-implantitis is generally known to be more aggressive, with comparatively rapid progression and less predictable treatment outcomes, especially when advanced. An understanding of molecular mechanisms underpinning the similarities and differences between peri-implantitis and periodontitis is essential to develop novel management strategies. This study aimed to compare long non-coding RNAs (lncRNAs) and messenger RNA (mRNA) expression profiles between peri-implantitis and periodontitis. METHODS: Inflamed soft tissue from peri-implantitis and periodontitis lesions, and healthy gingival tissue controls were analyzed by microarray. Cluster graphs, gene ontology (GO) analysis, and pathway analysis were performed. Quantitative real-time PCR was employed to verify microarray results. The expression levels of RANKL and OPG in the three tissue types were also evaluated, using qRT-PCR. Coding non-coding (CNC) network analyses were performed. RESULTS: Microarray analyses revealed 1079 lncRNAs and 1003 mRNAs as differentially expressed in peri-implantitis when compared to periodontitis. The cyclooxygenase-2 pathway was the most up-regulated biological process in peri-implantitis as compared to periodontitis, whereas hemidesmosome assembly was the most down-regulated pathway. Osteoclast differentiation was relatively up-regulated, and RANKL/OPG ratio was higher in peri-implantitis than in periodontitis. CONCLUSIONS: The study demonstrated that peri-implantitis and periodontitis exhibit significantly different lncRNA and mRNA expression profiles, suggesting that osteoclast differentiation-related pathways are comparatively more active in peri-implantitis. These data highlight potential molecular targets for periodontitis and peri-implantitis therapy development.

Improved scanning accuracy with newly designed scan bodies: An in vitro study comparing digital versus conventional impression techniques for complete-arch implant rehabilitation.

OBJECTIVES: To compare the accuracy of an original and two newly designed CAD/CAM scan bodies used in digital impressions with one another as well as conventional implant impressions. MATERIAL AND METHODS: A reference model containing four implants was fabricated. Digital impressions were taken using an intraoral scanner with different scan bodies: original scan bodies for Group I (DO), CAD/CAM scan bodies without extensional structure for Group II (DC), and CAD/CAM scan bodies with extensional structure for Group III (DCE). For Group IV, conventional splinted open-tray impressions (CI) were taken. The reference model and conventional stone casts were digitalized with a laboratory reference scanner. The Standard Tessellation Language datasets were imported into an inspection software for trueness and precision assessment. Statistical analysis was performed with a Kruskal-Wallis test and Dunn-Bonferroni test. The level of significance was set at α = .05. RESULTS: The median of trueness was 35.85, 38.50, 28.45, and 25.55 µm for Group I, II, III, and IV, respectively. CI was more accurate than DO (p = .015) and DC (p = .002). The median of precision was 48.40, 48.90, 27.30, and 19.00 for Group I, II, III, and IV, respectively. CI was more accurate than DO (p < .001), DC (p < .001), and DCE (p = .007). DCE was more accurate than DC (p < .001) and DO (p < .001). CONCLUSIONS: The design of the extensional structure could significantly improve scanning accuracy. Conventional splinted open-tray impressions were more accurate than digital impressions for full-arch implant rehabilitation.

Correlation of anterior overbite with root position and buccal bone thickness of maxillary anterior teeth: a CBCT study.

PURPOSE: To investigate the correlation of anterior overbite with the sagittal root position (SRP) and buccal bone thickness (BBT) of the maxillary anterior teeth. METHODS: Cone-beam computed tomography (CBCT) data of southern Chinese patients who underwent CBCT examinations between November 2016 and December 2016 were collected. The anterior overbite was the predictor variable while the SRP and the BBT at 4 mm apical to the cementoenamel junction (CEJ-4) and midpoint of the root of the maxillary anterior teeth were set as the primary and secondary outcome variables, respectively. All measurements were done by two calibrated examiners. Correlations between variables were analyzed by the Spearman's correlation coefficient. The significance level was set at P < 0.05. RESULTS: CBCT data of 146 patients (65 men and 81 women) with a mean age of 44.2 ± 13.4 years were analyzed, and of the 876 maxillary anterior teeth evaluated, 9.8% were presented with deep overbites. Most of roots of the anterior teeth (94.9%) were positioned against the buccal cortical plate, of which, in 63.8% of them the apex was not covered by bone along the long axis of the tooth. The mean BBT at CEJ-4 was 0.89 mm at the central incisor, 0.85 mm at the lateral incisor and 0.84 mm at the canine. The overbite was positively correlated with SRP Class I subtypes and the BBT at CEJ-4 (P < 0.05). CONCLUSION: Deep overbite was more frequently accompanied by bone fenestration in the anterior maxillary areas.

Clinical and Radiologic Outcomes of Submerged and Nonsubmerged Bone-Level Implants with Internal Hexagonal Connections in Immediate Implantation: A 5-Year Retrospective Study.

PURPOSE: To evaluate the 5-year clinical and radiologic outcome of immediate implantation using submerged and nonsubmerged techniques with bone-level implants and internal hexagonal connections and the effects of potential influencing factors. MATERIALS AND METHODS: A total of 114 bone-level implants (XiVE S plus) with internal hexagonal connections inserted into 72 patients were included. Patients were followed up for 5 years. A t-test was used to statistically evaluate the marginal bone loss between the submerged and nonsubmerged groups. The cumulative survival rate (CSR) was calculated according to the life table method and illustrated with Kaplan-Meier survival curves. Comparisons of the CSR between healing protocols, guided bone regeneration, implants with different sites, lengths, and diameters were performed using log-rank tests. RESULTS: The 5-year cumulative implant survival rates with submerged and nonsubmerged healing were 94% and 96%, respectively. No statistically significant differences in terms of marginal bone loss, healing protocol, application of guided bone regeneration, implant site, or length were observed. CONCLUSIONS: High CSRs and good marginal bone levels were achieved 5 years after immediate implantation of bone-level implants with internal hexagonal connections using both the submerged and nonsubmerged techniques. Factors such as implant length, site, and application of guided bone regeneration did not have an impact on the long-term success of the implants.

Analysis of Bone Height Changes after Maxillary Sinus Augmentation with Simultaneous and Delayed Placement of Dental Implants: A Clinical and Radiographic Study.

PURPOSE: To retrospectively assess the changes of the vertical height of the maxillary sinus floor after augmentation with simultaneous and delayed placement of implants. MATERIALS AND METHODS: In total, 38 patients with 76 implants were involved; vertical bone height of the sinus floor was radiographically measured at different stages including preoperation, immediately postsurgery, 6 and 12 months postsurgery, and 6 and 24 months postfunctional loading. RESULTS: Sinus augmentation significantly increased vertical bone height of the sinus floor for both the simultaneous and delayed groups. The survival rate was 100% in the simultaneous group and 95.46% in the delayed group. For simultaneous placement, the vertical bone height of the sinus floor at 6 and 12 months postsurgery was significantly less than that immediately postsurgery. For both groups, augmented bone height of the sinus floor showed significant decrease from 6 months to 24 months postfunctional loading. The mean value of final bone augmentation was 5.85 mm for simultaneous placement and 5.80 mm for delayed placements. CONCLUSION: Sinus augmentation with simultaneous and delayed placement of implants led to similar survival rates and bone augmentation. Resorption of augmentative bone was evident at 24 months postfunctional loading in both cases.

Influence of placement depth on bone remodeling around tapered internal connection implants: a histologic study in dogs.

OBJECTIVES: To evaluate the influence of implant-abutment interface (IAI) placement depth on bone remodeling around implants with two different types of tapered internal IAI: screwed-in (SI) and tapped-in (TI) connections in dogs. MATERIALS AND METHODS: Eight weeks post mandibular tooth extraction in six beagle dogs, two SI implants (OsseoSpeed(™), Astra Tech, DENTSPLY) and two TI implants (Integra-CP(™), Bicon LLC) were placed in one side of the mandible. The four experimental groups were as follows: (i) SI-placed equicrestally (SIC); (ii) TI-placed equicrestally (TIC); (iii) SI-placed 1.5 mm subcrestally (SIS); and (iv) TI-placed 1.5 mm subcrestally (TIS). Healing abutments were connected 12 weeks after implant placement. Sixteen weeks later, the dogs were sacrificed and histomorphometric analysis was performed. Histometrical outcomes were evaluated using a nonparametric Brunner-Langer model. RESULTS: Mean distance from the IAI to first bone-implant contact (IAI-fBIC) was 0.88 mm (median: 0.77; SD: 0.54) for SIC group, 1.23 mm (median: 1.22; SD: 0.66) for TIC group, 0.41 mm (median: 0.31; SD: 0.36) for SIS group, and 0.41 mm (median: 0.26; SD: 0.45) for TIS group. Subcrestal groups showed lower IAI-fBIC compared with equicrestal groups (P < 0.001). Connective tissue presented similar measurements regardless of the IAI placement depth and IAI type (P > 0.05), but the epithelium length and peri-implant soft tissue length in subcrestal groups were significant larger than that in the equicrestal groups (P < 0.001 and P = 0.004, respectively). CONCLUSION: Subcrestal implant placement with tapered internal IAI is beneficial for bone contact with the implant neck, and concurrently, it may not increase the soft tissue inflammation around IAI.

Effects of fluoridation of porcine hydroxyapatite on osteoblastic activity of human MG63 cells.

Biological hydroxyapatite, derived from animal bones, is the most widely used bone substitute in orthopedic and dental treatments. Fluorine is the trace element involved in bone remodeling and has been confirmed to promote osteogenesis when administered at the appropriate dose. To take advantage of this knowledge, fluorinated porcine hydroxyapatite (FPHA) incorporating increasing levels of fluoride was derived from cancellous porcine bone through straightforward chemical and thermal treatments. Physiochemical characteristics, including crystalline phases, functional groups and dissolution behavior, were investigated on this novel FPHA. Human osteoblast-like MG63 cells were cultured on the FPHA to examine cell attachment, cytoskeleton, proliferation and osteoblastic differentiation for in vitro cellular evaluation. Results suggest that fluoride ions released from the FPHA play a significant role in stimulating osteoblastic activity in vitro, and appropriate level of fluoridation (1.5 to 3.1 atomic percents of fluorine) for the FPHA could be selected with high potential for use as a bone substitute.

Leptin and its receptor expression in dental and periodontal tissues of primates.

Leptin and its receptor (OBR) have attracted much attention since their discovery. They have been reported to play central roles in energy balance, the immune-inflammatory response and bone metabolism. Evidence indicates that leptin and OBR are associated with inflammatory diseases of dental and periodontal tissues. The first step for establishing this is to determine the expression of leptin and OBR in these tissues. Our study is the first to examine systematically the expression of leptin and OBR in dental and periodontal tissues of monkeys (Macaca fascicularis) by immunohistochemistry and in primary cultured cells, isolated from human dental and periodontal tissues, by reverse transcription plus the polymerase chain reaction and immunocytochemistry. Our results show that leptin and OBR are constitutively expressed and widely distributed in dental and periodontal tissues of primates. Their immunoreaction is especially strong in junctional epithelium, a unique front-line defense around teeth and in mineralizing areas of the dental pulp and periodontal ligament. The expression of the long and also functional form of OBR (OBRb) indicates that leptin has a direct effect on these cells. Thus, we can reasonably infer that leptin and OBR exert effects on defense, mineralization and angiogenesis in dental and periodontal tissues of primates.

The effects of hospice care education on first-year undergraduate nursing students in mainland China: A mixed-methods study.

BACKGROUND: With the rising number of people with end-stage chronic diseases, the demand for hospice care has increased dramatically. As the future health professionals for the implementation of hospice care, undergraduate nursing students in mainland China still lack knowledge and skills of hospice care, thus hospice care education plays a vital role in its development. OBJECTIVES: To understand the effects of hospice care education on nursing students' death attitudes, end-of-life attitudes, humanistic care qualities, and their learning experiences. DESIGN: This study used a mixed-methods design. SETTING: A University of Chinese Medicine in mainland China. PARTICIPANTS: The first-year undergraduate nursing students (n = 65). METHODS: A mixed-methods study was conducted to evaluate the impact of a hospice care course from March to June 2021. The quantitative part included a quasi-experimental study designed with pre- and post-intervention measurements and the qualitative part included a descriptive qualitative study with semi-structured individual interviews. RESULTS: The quantitative data revealed that after the course, nursing students experienced improvements in their death attitudes, end-of-life attitudes, and humanistic care qualities. Two categories were identified from the qualitative data. The category of "Gain from learning" included 4 themes (Confronting death and thinking about life; Understanding and agreeing with the idea of hospice care; Perceiving the humanistic spirit of medicine; Enhancing of the nursing discipline cognition and professional identity) and the category of "Course feedback" included 2 themes (Expressing recognition for the course arrangement; Making suggestions on the course optimization). CONCLUSIONS: Hospice care education had a positive influence on nursing students. Students expressed satisfaction with the course arrangement. However, future hospice care courses should further optimize the curriculum designs by increasing the discussion of death-related topics, sharing more real clinical cases, recruiting students from different majors, and providing clinical practice, to provide high-quality nursing education for the development of hospice care.

Successful treatment of nasopalatine duct cyst after maxillary anterior implant surgery: a case report.

BACKGROUND: Sporadic studies have reported the occurrence of nasopalatine duct cysts after maxillary anterior implant surgery, and the treatment methods still have clinical uncertainty. PURPOSE: We report a potential therapy method that successfully treated a nasopalatine duct cyst that developed and expanded one year after maxillary anterior implant placement following periodontally hopeless teeth extraction. MATERIALS AND METHODS: The nasopalatine cyst was treated surgically without removing implants. During flap surgery, the cyst was removed intact, and the exposed implant's surface was debrided thoroughly by hydrogen peroxide (H2O2) rinsing, glycine air polishing, and saline rinsing. To deal with the significant bone defect caused by the cyst, a bovine porous bone mineral injected platelet-rich fibrin (BPBM-i-PRF) complex was applied to fill the defect, following a resorbable collagen membrane to cover. RESULTS: 7 years after surgery, no cyst recurrence was observed, and bone regeneration in the bone graft area was stable. The implants functioned well without mobility. CONCLUSIONS: For nasopalatine duct cysts associated with dental implant placement, complete surgical debridement and longitudinal stable bone regeneration are possibly accessible by regenerative surgery without implant removal.

A Standardized Rat Model to Study Peri-implantitis of Transmucosal Osseointegrated Implants.

With the high incidence rate, distinctive implant characteristic and unique infection pattern, peri-implantitis (PI) requires a specially designed implant animal model for the researches on the pathogenesis and treatments. Previous small-animal PI models exhibit variability in implant site selection, design, and surgical procedures resulting in unnecessary tissue damage and less effectivity. Herein, a quantitative-analysis-based standardized rat model for transmucosal PI-related research was proposed. After dissecting the anatomic structures of the rat maxilla, we determined that placing the implant anterior to the molars in the rat maxilla streamlined the experimental period and enhanced animal welfare. We standardized the model by controlling the rat strain, gender, and size. The customized implant and a series of matched surgical instruments were appropriately designed. A clear, step-by-step surgical process was established. These designs ensured the success rate, stability, and replicability of the model. Each validation method confirmed the successful construction of the model. This study proposed a quantitative-analysis-based standardized transmucosal PI rat model with improved animal welfare and reliable procedures. This model could provide efficient in vivo insights to study the pathogenesis and treatments of PI and preliminary screening data for further large-animal and clinical trials.

Clinical and radiographic results of crestal vs. subcrestal placement of implants in posterior areas: A split-mouth randomized controlled clinical trial.

OBJECTIVE: The objective of this study was to evaluate the peri-implant soft tissue and marginal bone loss (MBL) around implants with platform-switching and internal conical connection placed at crestal and subcrestal levels in posterior areas. MATERIALS AND METHODS: Nineteen partially edentulous patients with at least two adjacent missing teeth in posterior areas unilaterally or bilaterally were included. Forty-two implants were placed randomly at the crestal or subcrestal (1 mm) level in a split-mouth design. Implant-supported fixed dental prostheses with screw retention were delivered after 4 months of healing. Clinical and radiological measurements were performed at implant placement (T0), restoration delivery (T1), and 1-year follow-up after loading (T2). MBL was calculated as the change in distance from the implant-abutment interface to the first radiographically visible bone-implant contact. A repeated-measures mixed ANOVA followed by a paired Student's t-test with the Bonferroni correction was used for statistical analysis. p < 0.05 was considered statistically significant. RESULTS: Eighteen patients with thirty-eight implants completed the study at T2. The MBL was lower in the subcrestal group than in the crestal group (0.04 ± 0.08 vs. 0.17 ± 0.17 mm, p = 0.004). The peri-implant probing depth (PD) was 2.31 ± 0.48 mm in the subcrestal group and 1.92 ± 0.43 mm in the crestal group; this difference was statistically significant (p = 0.002). Intragroup comparison showed no significant differences in MBL, or PD around the crestal group and subcrestal group from T1 to T2. CONCLUSION: After 1 year of functional loading, subcrestal placement of implants with platform-switching and internal conical connection showed lower MBL and was associated with greater PD and peri-implant soft tissue height than implants placed at the crestal level.

Inhibitory effect of roflumilast on experimental periodontitis.

BACKGROUND: Phosphodiesterase-4 (PDE4) has been identified as a valid therapeutic target in several inflammatory diseases. In this study, we assessed PDE4 in gingival tissue from patients with chronic periodontitis and evaluated the therapeutic effects of the PDE4 inhibitor, roflumilast, in an experimental rat model of periodontitis. METHODS: Gingival tissue specimens from 20 healthy subjects and 20 patients with periodontitis were collected, and the mRNA expression levels of PDE4, interleukin (IL)-1ß, and IL-6 were assessed. Ninety rats were divided randomly into three groups (30 per group): non-ligature group, ligature-induced periodontitis group (L), and ligature-induced periodontitis with roflumilast administered group (5 mg/kg/d) (L+R). Rats were euthanized on days 3, 8, and 14. Alveolar bone resorption was analyzed using microcomputed tomography. Inflammation and osteoclast number were analyzed histologically. Finally, the mRNA expression levels of PDE-4, IL-1ß, IL-6, tumor necrosis factor (TNF)-α, and nuclear factor kappa B (NF-κB) were assessed in the rat gingival tissue. RESULTS: The mRNA expression levels of PDE4, IL-1ß, and IL-6 in the gingiva were significantly higher in patients with periodontitis compared with healthy individuals (P <0.05). Alveolar bone loss, degree of inflammation, number of TRAP-positive multinucleated osteoclasts, and mRNA expression levels of IL-1ß, IL-6, TNF-α, NF-κB, and PDE4 in the L+R group were significantly lower than those in the L group (P <0.05). CONCLUSIONS: PDE4 expression was increased in the gingiva of patients with periodontitis. Roflumilast may decrease alveolar bone loss and the expression of inflammatory cytokines in rats with ligature-induced periodontitis.

Effect of Scan Pattern on the Accuracy of Complete-Arch Digital Implant Impressions with Two Intraoral Scanners.

PURPOSE: To evaluate the effect of six scan patterns on the accuracy and speed of digital impressions with two different intraoral scanners for complete-arch implant rehabilitation. MATERIALS AND METHODS: A master model containing six parallelly placed implant analogs was fabricated, and six scan bodies were connected to the analogs. Reference scan was obtained with a laboratory scanner. Test scans were obtained by intraoral scanning with six scan patterns using 3Shape TRIOS 3 and Carestream CS 3600 intraoral scanners. Scanning time was recorded. Trueness and precision were assessed with an inspection software. Two-way analysis of variance (ANOVA) was performed to examine the effect of scan pattern, scanner, and their interaction on accuracy and scanning time. Differences between the six scan patterns with each scanner were tested by one-way ANOVA. Differences between the two scanners were evaluated by t test. The level of significance was set at α = .05. RESULTS: For trueness, the effects of scanner, scan pattern, and their interaction were significantly different in both linear and angular discrepancy. For precision, the scanner and scan pattern each had a significant effect on linear discrepancy independently, while their interaction did not. Only the effects of scanners were significantly different in angular discrepancy. For each of the two scanners, significant differences were detected in accuracy and speed between the patterns. CONCLUSION: Scan pattern significantly influenced the accuracy and speed of digital impressions for complete-arch implant rehabilitation.