Comparison of peri-implant crevicular fluid levels of adrenomedullin and human beta defensins 1 and 2 from mandibular implants with different implant stability quotient levels in nonsmoker patients

Human β-defensins and their synthetic analogs: Natural defenders and prospective new drugs of oral health

As a family of cationic host defense peptides, human β-defensins (HBDs) are ubiquitous in the oral cavity and are mainly synthesized primarily by epithelial cells, serving as the primary barrier and aiming to prevent microbial invasion, inflammation, and disease while maintaining physiological homeostasis. In recent decades, there has been great interest in their biological functions, structure-activity relationships, mechanisms of action, and therapeutic potential in oral diseases. Meanwhile, researchers are dedicated to improving the properties of HBDs for clinical application. In this review, we first describe the classification, structural characteristics, functions, and mechanisms of HBDs. Next, we cover the role of HBDs and their synthetic analogs in oral diseases, including dental caries and pulp infections, periodontitis, peri-implantitis, fungal/viral infections and oral mucosal diseases, and oral squamous cell carcinoma. Finally, we discuss the limitations and challenges of clinical translation of HBDs and their synthetic analogs, including, but not limited to, stability, bioavailability, antimicrobial activity, resistance, and toxicity. Above all, this review summarizes the biological functions, mechanisms of action, and therapeutic potential of both natural HBDs and their synthetic analogs in oral diseases, as well as the challenges associated with clinical translation, thus providing substantial insights into the laboratory development and clinical application of HBDs in oral diseases.

Marginal Bone Level Measurements of Unsplinted Implants Used for Mandibular Overdentures: A Six-Month Randomized Prospective Clinical Study Comparing Early and Delayed Loading Protocols

Background and purpose Implant-supported mandibular overdentures are a good alternative for patients having poor retention of mandibular conventional dentures. The aim of this prospective study was to evaluate and compare the results between early loading and delayed loading of mandibular overdentures on two unsplinted implants. Materials and methods  A total of 14 completely edentulous male patients in the age group of 50-60 years were selected for the study. Two 3.5×13 mm implants were placed in the mandibular interforaminal region. The patients were divided into two groups: (i) the test group in which the overdenture was connected after one week of surgery, and (ii) the control group, in which the overdenture was connected three months after surgery. Marginal bone levels were evaluated at baseline (during loading), three months, and six months post loading. Unpaired 't' test was used for the comparison of intergroup measurements.  Results No implants were lost. Marginal bone resorptions showed no statistically significant differences between the two groups over six months period after loading. Conclusion The results of this prospective clinical study suggested that there was no significant difference in the clinical and radiographic state of patients treated with implant-supported mandibular overdentures loaded either one week or three months after implant surgery.

Immediate and early loading of hydrothermally treated, hydroxyapatite-coated dental implants: a 7-year prospective randomized clinical study

Background

Existing research on marginal bone stability around hydroxyapatite (HA)-coated implants often lacks adequate long-term follow-up. The purpose of this randomized prospective study was to evaluate the 7-year outcome of patients with immediate and early loaded single-tooth restorations supported by implants with plasma-sprayed, partially HA-coated surfaces. Forty-two patients in need of 50 single implants were treated in in the Postgraduate Periodontics Clinic of Louisiana State University School of Dentistry. Implants were randomly divided into 2 groups: Group A was immediately loaded, and Group B was early loaded. Continuous follow-up with periodic maintenance care and radiographic evaluations was performed. The primary outcome of interest was implant survival, characterized using the Kaplan–Meier method. Secondary study outcome consisted of peri-implant crestal bone level changes. Data on age, sex, bone quality, implant location, length and diameter, and prior augmentation of the site were collected. Multiple regression analyses were conducted to determine whether the independent variables were associated with bone loss.

Results

One implant failed to maintain stability and was removed at 3 weeks. Thirty-four patients (14 males, 20 females with a total of 42 implants) completed the 7-year follow-up visit. Average age of evaluable patients was 52 in Group A and 55 in Group B. No significant difference was observed regarding sex and age distribution between the 2 groups. No significant difference was detected in the distribution of implant locations, types of bone, implant length, implant diameter, and augmentation status of the bone between the 2 groups. After 7 years of functioning for the 42 implants examined, implant survival rate was 100% for Group A and 95.5% for Group B. The results from this study of 50 implants showed that HA-coated Zimmer Tapered Screw-Vent Implants were clinically effective, with an overall cumulative 7-year survival rate of 98.0%. When comparing radiographic bone levels between 2-year and 7-year follow-ups, no significant differences in bone loss were found between Group A and Group B.

Conclusions

After 7 years in function, implants partially coated with plasma-sprayed and hydrothermally treated HA were clinically predictable when restored in occlusion immediately after or 3 weeks after implant placement.

Immediate loading implants: review of the critical aspects

Purpose

Modern dentistry have witnessed, a rapid and continuing evolution. Concerning the implant-rehabilitation protocols, they have been redefined in order to satisfy patient's increasing expectations in terms of comfort, aesthetic and shorter treatment period. The purpose of this review is to explore the concept of implant immediate loading and the indications for clinical practice. All the critical aspects that could influence the outcomes of this treatment will also be considered.

Materials and methods

Three protocols for implant load timing have been classified: immediate loading implants (ILI); early loading implants (ELI); and conventional loading implants (CLI). Two subclassifications point out the different loading modality: 1) Occlusal loading or Non-Occlusal loading, 2) Direct loading or Progressive loading. Micromovements have been considered, since the start of implant dentistry, one of the main risk for the success of osseointegration. The determinant and most accessible parameter to assess the primary stability is the implant insertion torque value. To achieve the necessary torque value to perform immediate loading, it is therefore important to evaluate the bone density at the implant site. Computerized tomography (CT) has been regarded as the best radiographic method to evaluate the residual bone.

Results

The clinical success of this technique is highly dependent on many factors: patient selection, bone quality and quantity, implant number and design, implant primary stability, occlusal loading and clinician's surgical ability. Among these, implant primary stability is undoubtedly the most important.

Conclusion

Studies on ILI show that successful outcome can be expected, if the previous criteria are fulfilled. It seems that ILI demonstrate a greater risk for implant failure when compared to CLI, although the survival rates were high for both the procedures. The use of different surgical procedures, type of prostheses, loading times and have very different study designs. This lack of homogeneity limits the relevance of the conclusions that can be drawn.

The antimicrobial peptide, human β-defensin-1, potentiates in vitro osteoclastogenesis via activation of the p44/42 mitogen-activated protein kinases

Previous studies have demonstrated increased expression and raised levels of human β-defensin (hBD)-1 in gingival tissue and crevicular fluid of patients with chronic periodontitis and peri-implantitis, oral bone-resorbing diseases caused by enhanced osteoclastogenesis. Therefore, we aimed to investigate the effect of hBD-1 on osteoclast formation and function and to elucidate the involved signaling pathway in vitro. Human peripheral blood mononuclear cells (PBMCs) were first incubated with various doses of hBD-1 and cell viability was assayed by MTT. PBMCs were treated with macrophage-colony stimulating factor and receptor activator of nuclear factor kappa-B ligand (RANKL) in the presence or absence of non-toxic doses of hBD-1. In vitro osteoclastogenesis was analyzed by tartrate-resistant acid phosphatase (TRAP) staining, osteoclast-specific gene expression, and a resorption pit assay. Involvement of mitogen-activated protein kinases (MAPKs) was studied by immunoblotting and specific MAPK inhibitors. HBD-1 potentiated induction of in vitro osteoclastogenesis by RANKL, as shown by significantly increased number of TRAP-positive multinuclear cells and resorption areas on the dentin slices, and further up-regulated expressions of osteoclast-specific genes compared to those by RANKL treatment (p <0.05). However, hBD-1 treatment without RANKL failed to induce formation of osteoclast-like cells. A significant and further increase in transient phosphorylation of the p44/42 MAPKs was demonstrated by hBD-1 co-treatment (p<0.05), consistent with the inhibitory effect by pretreatment with U0126 or PD98059 on hBD-1-enhanced osteoclastogenesis. Collectively, hBD-1 potentiates the induction of in vitro osteoclastogenesis by RANKL via enhanced phosphorylation of the p44/42 MAPKs.

Enamel matrix derivative improves gingival fibroblast cell behavior cultured on titanium surfaces

OBJECTIVE

Although an extensive amount of research has demonstrated the positive effects of an enamel matrix derivative (EMD) on soft tissue wound healing around intrabony defects, little information is available describing its effect on peri-implant soft tissues, an area that has recently gained tremendous awareness due to the increasing prevalence of peri-implantitis. The aim of the present study was to assess the role of EMD when gingival fibroblasts were cultured on titanium surface with different surface topographies.

METHODS

Human primary gingival fibroblasts were cultured on pickled (PT) and sand-blasted with large grit followed by acid etching (SLA) surfaces and assessed for cell adhesion at 2, 4, and 8 h, cell morphology at 2, 4, 8, and 24 h as well as cell proliferation at 1, 3, and 5 days post-seeding. Furthermore, genes encoding collagen 1a1, vascular endothelial growth factor-A (VEGF-A), and fibronectin were assessed by real-time PCR. Human gingival fibroblasts were also quantified for their ability to synthesize a collagen matrix on the various titanium surfaces with and without EMD by immunofluorescence staining.

RESULTS

The results from the present study demonstrate that EMD significantly increased cell spreading at 2, 4, 8, and 24 h on PT surfaces and 4, 8, and 24 h on SLA surfaces. Furthermore, proliferation at 5 days on PT surfaces and 3 and 5 days on SLA surfaces was also increased for groups containing EMD. Real-time PCR results demonstrated that the culture of gingival fibroblasts with EMD significantly increased extracellular matrix synthesis of collagen 1 as well as improved mRNA levels of VEGF-A and fibronectin. Collagen1 immuno-fluorescent staining revealed a significantly higher area of staining for cells seeded on PT + EMD at 7 and 14 days and 14 days for SLA + EMD when compared to control samples.

CONCLUSION

The results from the present study favor the use of EMD for colonization of gingival fibroblasts on titanium surfaces by increasing cell growth, spreading, and synthesis of an extracellular matrix. The improvements were primarily irrespective of surface topography. Future animal and human studies are necessary to fully characterize the beneficial effects of incorporating EMD during soft tissue regeneration of implant protocols.

CLINICAL RELEVANCE

The use of EMD may speed up the quality of soft tissue integration around dental implants by facilitating gingival cell attachment, proliferation, and matrix synthesis of collagen 1.

Role of primary stability for successful osseointegration of dental implants: Factors of influence and evaluation

A secure implant primary (mechanical) stability is positively associated with a successful implant integration and long-term successful clinical outcome. Therefore, it is essential to assess the initial stability at different time-points to ensure a successful osseointegration. The present study critically reviews the factors that may play a role in achieving a successful initial stability in dental implants. Databases were searched from 1983 up to and including October 2013 using different combinations of various keywords. Bone quality and quantity, implant geometry, and surgical technique adopted may significantly influence primary stability and overall success rate of dental implants.