Osteoblast cell behavior on polyetheretherketone dental implant surfaces treated with different grit size aluminum oxide particles: An in vitro analysis.

STATEMENT OF PROBLEM: The hydrophobic and bioinert nature of polyetheretherketone (PEEK) implants needs to be addressed for successful osseointegration. PURPOSE: The purpose of this in vitro study was to evaluate the osteoblast cell behavior on PEEK implant surfaces treated with airborne-particle abrasion using different grit size aluminum oxide (Al2O3) particles. MATERIAL AND METHODS: Disk-shaped specimens (n=96) were prepared from medical grade PEEK rods and were distributed into 4 groups (n=24) of untreated PEEK (PEEK 0), airborne-particle abrasion using 50-µm Al2O3 particles (PEEK 50), airborne-particle abrasion using 110-µm Al2O3 particles (PEEK 110), and airborne-particle abrasion using 150-µm Al2O3 particles (PEEK 150). The surface characteristics were assessed using water contact angle (WCA) measurements and scanning electron microscopy (SEM). MG-63 osteoblast cells were cultured, and the biocompatibility of PEEK was assessed using a CellTiter-blue cell viability assay and florescence staining at day 1, 3, and 7. The specimens were stained with Alizarin red to assess the osteoblast cell differentiation on day 10 and 14. The Levene test was used to test the homogeneity of variances. One-way and Welch ANOVA with post hoc corrections were used to assess the overall statistical significance of differences among the groups (α=.05). RESULTS: The lowest mean WCA was demonstrated in PEEK 150 (49.25 ±5.51) and the highest in PEEK 0 (89.14 ±4.24) (P<.001). SEM images of PEEK 150 illustrated a more complex structure with a large area of globular outcroppings throughout the surface. PEEK 150 showed the highest cell metabolic activity at each time point with florescence staining showing a substantial cell confluence at day 3 and 7. Although PEEK 150 did not show a significant increase in cell proliferation, the number of cells attached was significantly higher than other groups (P<.05). PEEK 110 and 150 also showed a substantial increase in the extent of mineralization. CONCLUSIONS: Airborne-particle abrasion using moderate Al2O3 grit size (110- or 150-µm) improved the hydrophilicity and osteoblast cell behavior on PEEK implants.

Supportive care for the prevention of disease recurrence/progression following peri-implantitis treatment: A systematic review.

OBJECTIVES: This systematic review aimed to evaluate the efficacy of supportive care provision, frequency and protocol in patients treated for peri-implantitis, as reported in prospective and retrospective studies of at least 3-years duration. MATERIALS AND METHODS: A systematic search of three electronic databases was undertaken up to 21 July 2022 and supplemented by hand-search to identify studies that included participants treated for peri-implantitis and followed for at least 3 years. Owing to high heterogeneity, a meta-analysis was not appropriate, and therefore, data and risk of bias were explored qualitatively. PRISMA guidelines for reporting were followed. RESULTS: The search identified 2596 studies. Of 270 records selected during screening, 255 were excluded through independent review and 15 studies (10 prospective and 5 retrospective, with at least 20 patients) were retained for qualitative assessments. Study designs, population characteristics, supportive care protocols and reported outcomes varied markedly. Thirteen of the 15 studies had low risk of bias. Supportive peri-implant care (SPIC) following different surgical peri-implantitis treatment protocols and with recall intervals varying between 2 months and annually resulted in peri-implant tissue stability (no disease recurrence or progression) ranging from 24.4% to 100% at patient level and from 28.3% to 100% at implant level. Sevenhundred and eighty-five patients with 790 implants were included in this review. CONCLUSIONS: Provision of SPIC following peri-implantitis therapy may prevent disease recurrence or progression. Insufficient evidence is available to identify (i) a specific supportive care protocol for secondary prevention of peri-implantitis, (ii) the effect of adjunctive local antiseptic agents in the secondary prevention of peri-implantitis and (iii) the impact of frequency of supportive care measures. Prospective, randomised, controlled studies designed to evaluate supportive care protocols are needed in future.

Interproximal tooth cleaning operated by a tactile robot. An in vitro analysis.

AIM: New technologies such as tactile robots and artificial intelligence are about to find their way into clinical practice in dentistry and may contribute to the improvement of oral health care in the future. In this study we hypothesized that a collaborative, tactile robot programmed by a dental student removes interproximal artificial plaque as effectively as a human operator in an in vitro pilot trial. MATERIAL AND METHODS: Model teeth were fully covered with artificial plaque and set into phantom jaws. First, a robot was programmed by a dental student to perform interproximal cleaning with an interproximal brush. Second, teeth were covered with artificial plaque again and the dental student performed the interproximal cleaning manually. Both experiments were repeated five times. Residual plaque was measured with binary pictures. Surface coverage was reported and comparison of methods was performed with significance defined at a= 0.05. RESULTS: No statistically significant difference was found in the cleaning result between the robot and the human operator. CONCLUSION: The results of this in vitro pilot study indicate that a tactile robot with integrated artificial intelligence programmed by a dental student can perform interproximal cleaning as effectively as the dental student. Practical lmplications: In the future, the use of robot assistants to support oral hygiene, e.g., in patients with reduced motor skills or impaired vision may be further investigated.

Dentronics: tooth cleaning with a tactile collaborative robot - an in vitro proof of concept.

AIM: The aim of the present study was to compare the performance of a tactile collaborative robot programmed by a dental professional (DP) with that of a DP in the removal of surrogate plaque in vitro. MATERIALS AND METHODS: Six typodont teeth in articulated jaws were covered with surrogate plaque and cleaned by a DP with the help of a manual toothbrush (DP/manual) and an electric toothbrush (DP/electric). The experiment was repeated with the help of a collaborative seven-axis tactile robot programmed by a DP handling a manual toothbrush (robot/manual) and an electric toothbrush (robot/electric). All experiments were repeated five times, resulting in a total of N = 30 teeth in each group. Cleaning results were reported as the percentage of surface area with residual plaque. RESULTS: The cleaning results of the DP and the robot showed no significant differences. However, electric toothbrushing was significantly less effective compared with manual toothbrushing (P < 0.05). CONCLUSION: The present in vitro study indicates that current robot technology may perform the removal of surrogate plaque as efficiently as a DP. In future, this may be helpful to release nursing staff from this time-demanding task that could possibly cause contagion or to support people with reduced motor skills or impaired vision in performing daily oral hygiene.

Antibacterial and Cytocompatible: Combining Silver Nitrate with Strontium Acetate Increases the Therapeutic Window.

Microbial infection and insufficient tissue formation are considered to be the two main causes of dental implant failure. Novel studies have focused on designing dual-functional strategies to promote antibacterial properties and improve tissue cell response simultaneously. In this study, we investigated the antibacterial properties and cytocompatibility of silver nitrate (AgNO3) and strontium acetate (SrAc) in a mono-culture setup for dental application. Additionally, we defined the therapeutic window between the minimum inhibitory concentration against pathogenic bacteria and maximum cytocompatible dose in the case of combined applications in a co-culture setup. Antibacterial properties were screened using Aggregatibacter actinomycetemcomitans and cell response experiments were performed with osteoblastic cells (MC3T3) and fibroblastic cells (NIH3T3). The osteoinductive behavior was investigated separately on MC3T3 cells using alizarin red staining. A therapeutic window for AgNO3 as well as SrAc applications could be defined in the case of MC3T3 cells while the cytocompatibility of NIH3T3 cells was compromised for all concentrations with an antibacterial effect. However, the combined application of AgNO3/SrAc caused an enhanced antibacterial effect and opened a therapeutic window for both cell lines. Enhanced mineralization rates could be observed in cultures containing SrAc. In conclusion, we were able to demonstrate that adding SrAc to AgNO3 not only intensifies antibacterial properties but also exhibits bone inductive characteristics, thereby offering a promising strategy to combat peri-implantitis and at the same time improve osseointegration in implant therapy.

Early host-microbe interaction in a peri-implant oral mucosa-biofilm model.

The host-microbe relationship is pivotal for oral health as well as for peri-implant diseases. Peri-implant mucosa and commensal biofilm play important roles in the maintenance of host-microbe homeostasis, but little is known about how they interact. We have therefore investigated the early host-microbe interaction between commensal multispecies biofilm (Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar, Porphyromonas gingivalis) and organotypic peri-implant mucosa using our three-dimensional model. After 24 hr, biofilms induced weak inflammatory reaction in the peri-implant mucosa by upregulation of five genes related to immune response and increased secretion of IL-6 and CCL20. Biofilm volume was reduced which might be explained by secretion of ß-Defensins-1, -2, and CCL20. The specific tissue reaction without intrinsic overreaction might contribute to intact mucosa. Thus, a relationship similar to homeostasis and oral health was established within the first 24 hr. In contrast, the mucosa was damaged and the bacterial distribution was altered after 48 hr. These were accompanied by an enhanced immune response with upregulation of additional inflammatory-related genes and increased cytokine secretion. Thus, the homeostasis-like relationship was disrupted. Such profound knowledge of the host-microbe interaction at the peri-implant site may provide the basis to improve strategies for prevention and therapy of peri-implant diseases.

The human oral phageome.

Oral bacteriophages (or phages), especially periodontal ones, constitute a growing area of interest, but research on oral phages is still in its infancy. Phages are bacterial viruses that may persist as intracellular parasitic deoxyribonucleic acid (DNA) or use bacterial metabolism to replicate and cause bacterial lysis. The microbiomes of saliva, oral mucosa, and dental plaque contain active phage virions, bacterial lysogens (ie, carrying dormant prophages), and bacterial strains containing short fragments of phage DNA. In excess of 2000 oral phages have been confirmed or predicted to infect species of the phyla Actinobacteria (>300 phages), Bacteroidetes (>300 phages), Firmicutes (>1000 phages), Fusobacteria (>200 phages), and Proteobacteria (>700 phages) and three additional phyla (few phages only). This article assesses the current knowledge of the diversity of the oral phage population and the mechanisms by which phages may impact the ecology of oral biofilms. The potential use of phage-based therapy to control major periodontal pathogens is also discussed.

The effect of keratinized mucosa on the severity of peri-implant mucositis differs between periodontally healthy subjects and the general population: a cross-sectional study.

OBJECTIVE: The study aims to investigate the effect of reduced keratinized mucosa (KM) and other risk indicators on the severity of peri-implant mucositis in (i) the general population, (ii) in periodontally healthy patients, and (iii) in periodontally healthy patients without a history of periodontitis. MATERIALS AND METHODS: Anamnesis and the following clinical parameters were taken: mucosal-index, bleeding on probing, local plaque index, oral hygiene-index, and width of KM. Mucositis severity score was determined for each implant. Multi-level and subgroup analysis was performed on the patient and implant level. RESULTS: Six hundred twelve implants in 130 patients were analyzed. Subgroup analysis showed significant associations between KM < 2 mm and the severity score in (ii) periodontally healthy patients (p = 0.014) and in (iii) patients without history of periodontitis (p = 0.017). Secondary outcome showed higher severity scores for patients with insufficient oral hygiene or without residual teeth (p ≤ 0.001), in maxillary implants (p = 0.04), and for the number of implants per patient (p ≤ 0.001). CONCLUSION: Within the limits of the study, one may conclude that a reduced width of KM is a risk indicator for the severity of peri-implant mucositis in periodontally healthy patients and patients without a history of periodontitis. CLINICAL RELEVANCE: The results indicate a band of ≥ 2 mm KM to reduce the severity of peri-implant mucositis in periodontally healthy patients.

Plant-based oral care product exhibits antibacterial effects on different stages of oral multispecies biofilm development in vitro.

BACKGROUND: Excessive biofilm formation on surfaces in the oral cavity is amongst the main reasons for severe infection development like periodontitis and peri-implantitis. Mechanical biofilm removal as well as the use of adjuvant antiseptics supports the prevention of pathogenic biofilm formation. Recently, the antibacterial effect of the oral care product REPHA-OS®, based on medicinal plant extracts and essential oils, has been demonstrated on oral pathogens grown on agar plates. In the present study, the effectiveness of the product on medical relevant oral biofilm development should be demonstrated for the first time. METHODS: An established in vitro oral multispecies biofilm, composed of Streptococcus oralis, Actinomyces naeslundii, Veillonella dispar and Porphyromonas gingivalis, was used to analyze the antibacterial effect of different REPHA-OS® concentrations on planktonic bacteria, biofilm formation and mature biofilms. It was quantified using metabolic activity assays and live/dead fluorescence staining combined with three-dimensional confocal laser-scanning microscopy. Additionally, effects on species distribution inside the biofilm were assessed by means of quantitative real-time PCR. RESULTS: REPHA-OS® showed statistically significant antimicrobial effects on all stages of biofilm development: a minimal inhibitory concentration of 5% could be detected for both, for planktonic bacteria and for biofilm formation. Interestingly, only a slightly higher concentration of 10% was necessary to completely kill all bacteria in mature biofilms also. In contrast, an influence on the biofilm matrix or the species distribution could not be observed. The effect could be attributed to the herbal ingredients, not to the contained ethanol. CONCLUSION: The strong antibacterial effect of REPHA-OS® on different stages of oral biofilm development strengthens its application as an alternative adjuvant in oral care therapies.

Removable denture is a risk indicator for peri-implantitis and facilitates expansion of specific periodontopathogens: a cross-sectional study.

BACKGROUND: The prevalence of peri-implantitis ranges between 7 and 38.4% depending on risk indicators such as smoking, diabetes mellitus, lack of periodontal maintenance program, and history or presence of periodontitis. Currently, the possible effect of the type of superstructure on peri-implant health is unclear. This cross-sectional study aims to investigate the influence of the superstructure on the prevalence of peri-implant mucositis, peri-implantitis and peri-implant dysbiosis. METHODS: During a 32-month recruitment period dental implants were assessed to diagnose healthy peri-implant tissues, mucositis or peri-implantitis. The study included 1097 implants in 196 patients. Out of all peri-implantitis cases 20 randomly chosen submucosal biofilms from implants with fixed denture (FD) originating from 13 patients and 11 biofilms from implants with removable dentures (RD) originating from 3 patients were studied for microbiome analysis. Composition of transcriptionally active biofilms was revealed by RNAseq. Metatranscriptomic profiles were created for thirty-one peri-implant biofilms suffering from peri-implantitis and microbiome changes associated with superstructure types were identified. RESULTS: 16.41% of the implants were diagnosed with peri-implantitis, 25.00% of implants with RD and 12.68% of implants with FD, respectively. Multivariate analysis showed a significant positive association on patient (p = < 0.001) and implant level (p = 0.03) between the prevalence of peri-implantitis and RD. Eight bacterial species were associated either with FD or RD by linear discriminant analysis effect size method. However, significant intergroup confounders (e.g. smoking) were present. CONCLUSIONS: Within the limitations of the present work, RDs appear to be a risk indicator for peri-implantitis and seem to facilitate expansion of specific periodontopathogens. Potential ecological and pathological consequences of shift in microbiome from RDs towards higher activity of Fusobacterium nucleatum subspecies animalis and Prevotella intermedia require further investigation.

In vitro evaluation of the influence of titanium nitride coating on the retention force between components of two-part abutments.

BACKGROUND: Two-part abutments are typically made up of a base composed of titanium and a ceramic build-up. The long-term outcomes are affected by the mechanical durability. The purpose of the present investigation was to evaluate and compare the retention force of two-part abutment systems with titanium or titanium nitride bases-as fixed with zirconia components and with various surface treatments. METHODS: A total of 60 two-part abutments were investigated-with a titanium base (n = 30) or titanium nitride coated bases (n = 30) and bonded with zirconia ceramic build-ups. The bonding surfaces were treated with aluminium oxide blasting, with an average particle size of 110 µm. The titanium bases were then pretreated with Alloy Primer or Clearfil Ceramic Primer. The ceramic build-ups were only treated with Clearfil Ceramic Primer. For twenty test specimens, no chemical pretreatment was performed. Test specimens were classified into six groups in accordance with the pretreatment (A-F; n = 10). A resin-based luting agent was employed to attach the two parts. Specimens were then subjected to artificial thermal aging (104 cycles with 5 °C/55 °C). The retention force between the two parts was then investigated with a pull-off test. The findings were analyzed by ANOVA statistics. Fracture patterns were examined by electron microscopy. RESULTS: In the absence of primer, titanium nitride coated bases gave significantly greater retention forces than other samples (p < 0.05). Chemical preconditioning with silane coupling agents did not effect on the retention force of coated bases. CONCLUSIONS: The results of the current study suggested that modifying metal surfaces by coating the base with titanium nitride not only has esthetic and biological advantages, but also enhances the mechanical properties of the adhesive bond of two-part abutments.

Evaluation of biofilm colonization on multi-part dental implants in a rat model.

BACKGROUND: Peri-implant mucositis and peri-implantitis are highly prevalent biofilm-associated diseases affecting the tissues surrounding dental implants. As antibiotic treatment is ineffective to fully cure biofilm mediated infections, antimicrobial modifications of implants to reduce or prevent bacterial colonization are called for. Preclinical in vivo evaluation of the functionality of new or modified implant materials concerning bacterial colonization and peri-implant health is needed to allow progress in this research field. For this purpose reliable animal models are needed. METHODS: Custom made endosseous dental implants were installed in female Sprague Dawley rats following a newly established three-step implantation procedure. After healing of the bone and soft tissue, the animals were assigned to two groups. Group A received a continuous antibiotic treatment for 7 weeks, while group B was repeatedly orally inoculated with human-derived strains of Streptococcus oralis, Fusobacterium nucleatum and Porphyromonas gingivalis for six weeks, followed by 1 week without inoculation. At the end of the experiment, implantation sites were clinically assessed and biofilm colonization was quantified via confocal laser scanning microscopy. Biofilm samples were tested for presence of the administered bacteria via PCR analysis. RESULTS: The inner part of the custom made implant screw could be identified as a site of reliable biofilm formation in vivo. S. oralis and F. nucleatum were detectable only in the biofilm samples from group B animals. P. gingivalis was not detectable in samples from either group. Quantification of the biofilm volume on the implant material revealed no statistically significant differences between the treatment groups. Clinical inspection of implants in group B animals showed signs of mild to moderate peri-implant mucositis (4 out of 6) whereas the mucosa of group A animals appeared healthy (8/8). The difference in the mucosa health status between the treatment groups was statistically significant (p = 0.015). CONCLUSIONS: We developed a new rodent model for the preclinical evaluation of dental implant materials with a special focus on the early biofilm colonization including human-derived oral bacteria. Reliable biofilm quantification on the implant surface and the symptoms of peri-implant mucositis of the bacterially inoculated animals will serve as a readout for experimental evaluation of biofilm-reducing modifications of implant materials.

Cell culture media notably influence properties of human mesenchymal stroma/stem-like cells from different tissues.

BACKGROUND AIMS: Mesenchymal stroma/stem-like cells (MSCs) are a popular cell source and hold huge therapeutic promise for a broad range of possible clinical applications. However, to harness their full potential, current limitations in harvesting, expansion and characterization have to be overcome. These limitations are related to the heterogeneity of MSCs in general as well as to inconsistent experimental protocols. Here we aim to compare in vitro methods to facilitate comparison of MSCs generated from various tissues. METHODS: MSCs from 3 different tissues (bone marrow, dental pulp, adipose tissue), exemplified by cells from 3 randomly chosen donors per tissue, were systematically compared with respect to their in vitro properties after propagation in specific in-house standard media, as established in the individual laboratories, or in the same commercially available medium. RESULTS: Large differences were documented with respect to the expression of cell surface antigens, population doubling times, basal expression levels of 5 selected genes and osteogenic differentiation. The commercial medium reduced differences in these parameters with respect to individual human donors within tissue and between tissues. The extent, size and tetraspanin composition of extracellular vesicles were also affected. CONCLUSIONS: The results clearly demonstrate the extreme heterogeneity of MSCs, which confirms the problem of reproducibility of results, even when harmonizing experimental conditions, and questions the significance of common parameters for MSCs from different tissues in vitro.

Commensal and pathogenic biofilms differently modulate peri-implant oral mucosa in an organotypic model.

The impact of oral commensal and pathogenic bacteria on peri-implant mucosa is not well understood, despite the high prevalence of peri-implant infections. Hence, we investigated responses of the peri-implant mucosa to Streptococcus oralis or Aggregatibacter actinomycetemcomitans biofilms using a novel in vitro peri-implant mucosa-biofilm model. Our 3D model combined three components, organotypic oral mucosa, implant material, and oral biofilm, with structural assembly close to native situation. S. oralis induced a protective stress response in the peri-implant mucosa through upregulation of heat shock protein (HSP70) genes. Attenuated inflammatory response was indicated by reduced cytokine levels of interleukin-6 (IL-6), interleukin-8 (CXCL8), and monocyte chemoattractant protein-1 (CCL2). The inflammatory balance was preserved through increased levels of tumor necrosis factor-alpha (TNF-α). A. actinomycetemcomitans induced downregulation of genes important for cell survival and host inflammatory response. The reduced cytokine levels of chemokine ligand 1 (CXCL1), CXCL8, and CCL2 also indicated a diminished inflammatory response. The induced immune balance by S. oralis may support oral health, whereas the reduced inflammatory response to A. actinomycetemcomitans may provide colonisation advantage and facilitate later tissue invasion. The comprehensive characterisation of peri-implant mucosa-biofilm interactions using our 3D model can provide new knowledge to improve strategies for prevention and therapy of peri-implant disease.

The effect of adjuvant oral irrigation on self-administered oral care in the management of peri-implant mucositis: A randomized controlled clinical trial.

OBJECTIVES: This single-blinded randomized clinical trial evaluated the effect of adjuvant oral irrigation in addition to self-administered oral care on prevalence and severity of peri-implant mucositis. MATERIAL & METHODS: After randomization, patients suffering from peri-implant mucositis were assigned to the following: Group 1 (control) received oral hygiene instruction following a standardized protocol, including a sub- and supramucosal mechanical debridement. Group 2 and 3 additionally were instructed to use an oral irrigator with either water or 0.06% CHX solution. One implant per patient was considered for examination. Clinical examinations included Probing Depth, Bleeding on Probing (BOP-positive sites), and Modified Plaque and Gingival Index. A surrogate variable (mucositis severity score) was applied measuring severity of disease. Statistical analysis included linear regression models and sensitivity analysis. RESULTS: Sixty periodontally healthy patients were examined for presence and severity of peri-implant mucositis. 70% of all patients reached complete resolution of disease after 12 weeks. The prevalence of peri-implant mucositis after 12 weeks was 50% in group 1, 35% in group 2, and 5% in group 3. Average BOP-positive sites were reduced in all groups after 12 weeks (mean change from baseline: group 1: -1.5; group 2: -1.8; group 3: -2.3). CONCLUSION: Within the limits of the study, adjuvant use of an oral irrigator with 0.06% CHX in addition to mechanical biofilm removal and oral hygiene instruction can reduce the presence and severity of peri-implant mucositis after 12 weeks.

Development of a peri-implantitis model in the rat.

OBJECTIVES: The aim of the present study was to establish a rodent peri-implantitis model induced by a mixed bacterial infection characterized by bone loss and semi-quantitative graduation of peri-implant inflammation in histological sections. MATERIALS AND METHODS: Two titanium implants were implanted in Sprague-Dawley rats, bilaterally in each maxilla. After 3 weeks healing, the rats were randomized into three groups according to different treatments over the next 3 months: Antibiotic-Group with oral lavage of antibiotics; Bacteria-Group with oral lavage of Streptococcus oralis and Aggregatibacter actinomycetemcomitans; and Untreated Group with standard housing and no additional treatment. Maxillae were dissected to perform microscopic and histological analysis of bone height and peri-implant tissues. RESULTS: The bone level, measured at one implant site per animal, in the Bacteria-Group (2.60 ± 0.39 mm) was significantly reduced compared to the Antibiotic-Group (2.29 ± 0.32 mm) after 3 months. The differences of bone height in the Bacteria-Group and the Untreated Group (2.46 ± 0.27 mm) did not reach statistical significance. The inflammatory response with respect to the number of inflammatory cells and fibrous tissue compartments of the peri-implant tissues in the Bacteria-Group was significantly increased compared with the Antibiotic-Group (p < .05). S. oralis and A. actinomycetemcomitans DNAs were detected in the Bacteria-Group. CONCLUSIONS: This rat model of peri-implantitis used oral bacterial lavage for the induction of an inflammatory host response and bone loss. Additional bacterial treatment enhances the peri-implant phenotype, so that significant differences to a reduced bacterial load similar to the human peri-implantitis disease can be identified.

Cell Type-Specific Adhesion and Migration on Laser-Structured Opaque Surfaces.

Cytocompatibility is essential for implant approval. However, initial in vitro screenings mainly include the quantity of adherent immortalized cells and cytotoxicity. Other vital parameters, such as cell migration and an in-depth understanding of the interaction between native tissue cells and implant surfaces, are rarely considered. We investigated different laser-fabricated spike structures using primary and immortalized cell lines of fibroblasts and osteoblasts and included quantification of the cell area, aspect ratio, and focal adhesions. Furthermore, we examined the three-dimensional cell interactions with spike topographies and developed a tailored migration assay for long-term monitoring on opaque materials. While fibroblasts and osteoblasts on small spikes retained their normal morphology, cells on medium and large spikes sank into the structures, affecting the composition of the cytoskeleton and thereby changing cell shape. Up to 14 days, migration appeared stronger on small spikes, probably as a consequence of adequate focal adhesion formation and an intact cytoskeleton, whereas human primary cells revealed differences in comparison to immortalized cell lines. The use of primary cells, analysis of the cell-implant structure interaction as well as cell migration might strengthen the evaluation of cytocompatibility and thereby improve the validity regarding the putative in vivo performance of implant material.

Keratinized mucosa width is associated with severity of peri-implant mucositis. A cross-sectional study.

OBJECTIVES: This is a cross-sectional study designed with the aim to assess associations between the width of keratinized tissue and peri-implant mucositis. MATERIALS AND METHODS: Two hundred and thirty one dental implants in 52 patients were evaluated. The width of keratinized mucosa (KM), plaque index (mPI), gingival index (mGI), bleeding on probing index (BoP), and the probing depth (PD) were measured clinically. Reduced KM was defined as a width of KM below 2 mm and 1 mm, respectively. In the primary analysis, data were analyzed on the implant level with the help of a generalized estimating equations (GEE) model. In sensitivity analyses, an adjusted linear mixed model was performed. RESULTS: Forty four implants in 12 patients had less than 2 mm KM, and 187 implants in 40 patients had ≥ 2 mm KM. In the non-adjusted analysis on the implant level, reduced keratinized tissue width was significantly associated with peri-implant mucositis (OR 3.3, 95%-CI (1.3-8.0), p = 0.009) and severity of disease (mean difference 2.5, 95%-CI (0.8-4.2) p = 0.004). In sensitivity analyses, reduced keratinized tissue showed a significant association with severity of disease (OR 1.7, 95%-confidence interval = 0.1-34, p = 0.040). CONCLUSION: A reduced width of keratinized tissue around dental implants is a risk indicator for severity of peri-implant mucositis. The overall tendency of the results indicates that a sufficient amount of KM may contribute to reduce risk for and severity of peri-implant mucositis.

Probing depth is an independent risk factor for HbA1c levels in diabetic patients under physical training: a cross-sectional pilot-study.

BACKGROUND: This cross-sectional study investigates the potential association between active periodontal disease and high HbA1c levels in type-2-diabetes mellitus subjects under physical training. METHODS: Women and men with a diagnosis of non-insulin-dependent diabetes mellitus and ongoing physical and an ongoing exercise program were included. Periodontal conditions were assessed according to the CDC-AAP case definitions. Venous blood samples were collected for the quantitative analysis of HbA1c. Associations between the variables were examined with univariate and multivariate regression models. RESULTS: Forty-four subjects with a mean age of 63.4 ± 7.0 years were examined. Twenty-nine subjects had no periodontitis, 11 had a moderate and 4 had a severe form of periodontal disease. High fasting serum glucose (p < 0.0001), high BMI scores (p = 0.001), low diastolic blood pressure (p = 0.030) and high probing depth (p = 0.036) were significantly associated with high HbA1c levels. CONCLUSIONS: Within the limitations of this study HbA1c levels are positively associated with high probing pocket depth in patients with non-insulin-dependent diabetes mellitus under physical exercise training. Control and management of active periodontal diseases in non-insulin-dependent patients with diabetes mellitus is reasonable in order to maximize therapeutic outcome of lifestyle interventions.

Stress Distribution in All-Ceramic Posterior 4-Unit Fixed Dental Prostheses Supported in Different Ways: Finite Element Analysis.

INTRODUCTION: The purpose of this finite element analysis (FEA) was to complement results of previously published studies that investigated the influence of abutment resilience on the load-bearing capacity of zirconia posterior 4-unit fixed dental prostheses (FDPs) with static load tests. MATERIALS AND METHODS: Duplicates of 3 different physical specimens were modeled for FEA. The first virtual specimen was supported by teeth with periodontal resilience, the second by the combination of tooth and implant, and the third by implants only. The center of the FDP was loaded, vertically to the occlusal plane. The highest maximum principal stresses (MPSs) were computed. DISCUSSION: The highest MPS in each model occurred in the basal region of the middle framework connector. Comparison between the 3 models showed that the tensile stresses were lower when the support of the FDP was more rigid. Numerically determined highest MPSs in the FDPs correlated well with experimentally observed load-bearing capacities. CONCLUSION: The FEA is well suited to confirm the in vitro study mentioned and complement the results with stress distributions in all-ceramic posterior 4-unit FDP.