In vitro stimulation of human gingival epithelial cell attachment to dentin by surface conditioning

Effects of Minocycline Hydrochloride as an Adjuvant Therapy for a Guided Bone Augmentation Procedure in The Rat Calvarium

This in vivo study reports the influence of minocycline-HCl administration on extra-skeletal bone generation in a Guided Bone Augmentation model, utilizing titanium caps placed on the intact as well as perforated calvaria of rats. The test group was administered 0.5 mg/mL minocycline-HCl with the drinking water, and the amount of bone tissue in the caps was quantified at three time points (4, 8 and 16 weeks). A continuously increased tissue fill was observed in all groups over time. The administration of minocycline-HCl as well as perforation of the calvaria increased this effect, especially with regard to mineralization. The strongest tissue augmentation, with 1.8 times that of the untreated control group, and, at the same time, the most mineralized tissue (2.3× over untreated control), was produced in the combination of both treatments, indicating that systemic administration of minocycline-HCl has an accelerating and enhancing effect on vertical bone augmentation.

Junctional epithelium and hemidesmosomes: Tape and rivets for solving the "percutaneous device dilemma" in dental and other permanent implants

The percutaneous device dilemma describes etiological factors, centered around the disrupted epithelial tissue surrounding non-remodelable devices, that contribute to rampant percutaneous device infection. Natural percutaneous organs, in particular their extracellular matrix mediating the "device"/epithelium interface, serve as exquisite examples to inspire longer lasting long-term percutaneous device design. For example, the tooth's imperviousness to infection is mediated by the epithelium directly surrounding it, the junctional epithelium (JE). The hallmark feature of JE is formation of hemidesmosomes, cell/matrix adhesive structures that attach surrounding oral gingiva to the tooth's enamel through a basement membrane. Here, the authors survey the multifaceted functions of the JE, emphasizing the role of the matrix, with a particular focus on hemidesmosomes and their five main components. The authors highlight the known (and unknown) effects dental implant - as a model percutaneous device - placement has on JE regeneration and synthesize this information for application to other percutaneous devices. The authors conclude with a summary of bioengineering strategies aimed at solving the percutaneous device dilemma and invigorating greater collaboration between clinicians, bioengineers, and matrix biologists.

Oral Soft Tissue Grafting

The presence of healthy soft tissue at the tooth and implant interface correlates to long-term success and stability in function and esthetics. Grafting procedures utilizing various techniques can be performed during any stage of the implant or restorative therapy. Materials of autogenous, allogeneic, and xenogeneic sources are available for oral soft tissue grafting. This article describes the classifications of soft tissue defects, treatment modalities, and materials used to enhance soft tissue quality and quantity and to achieve optimal esthetics and function around teeth and implants.

Tunnel/Pouch versus Coronally Advanced Flap Combined with a Connective Tissue Graft for the Treatment of Maxillary Gingival Recessions: Four-Year Follow-Up of a Randomized Controlled Trial

BACKGROUND

The long-term stability after soft tissue graft for covering gingival recession remains a pivotal goal for both patient and periodontist. Therefore, the aim of this study was to compare the four-year outcomes of the coronally advanced flap (CAF) versus the pouch/tunnel (POT) technique, both combined with connective tissue graft (CTG), for gingival recession treatment.

METHODS

Forty patients were initially randomly assigned to the control group (CAF + CTG; N = 20) and the test group (POT + CTG; N = 20). Clinical outcomes included mean root coverage (MRC) and complete root coverage (CRC), gingival thickness (GT), and keratinized tissue (KT) gain. Esthetic outcomes were also analyzed using the pink esthetic score (PES) and patient-reported outcome measures (PROMs). All outcomes initially assessed at six months were extended to four years post-surgery.

RESULTS

No significant differences were observed between the two patient groups in terms of MRC and CRC. At four years, significantly greater GT and KT gain were noted in the POT + CTG group, and tissue texture enhancement was also more prominent in the test group.

CONCLUSIONS

The POT + CTG technique allows for long-term clinical coverage of gingival recessions comparable to that of the CAF + CTG technique, but it potentially improves gingival thickness, keratinized tissue and esthetic results.

Effect of citric acid, tetracycline, and doxycycline on instrumented periodontally involved root surfaces: A SEM study

BACKGROUND

A surface smear layer consisting of organic and inorganic material is formed on the root surface following mechanical instrumentation and may inhibit the formation of new connective tissue attachment to the root surface. Modification of the tooth surface by root conditioning has resulted in improved connective tissue attachment and has advanced the goal of reconstructive periodontal treatment.

AIM

The aim of this study was to compare the effects of citric acid, tetracycline, and doxycycline on the instrumented periodontally involved root surfaces in vitro using a scanning electron microscope.

SETTINGS AND DESIGN

A total of 45 dentin samples obtained from 15 extracted, scaled, and root planed teeth were divided into three groups.

MATERIALS AND METHODS

The root conditioning agents were applied with cotton pellets using the Passive burnishing technique for 5 minutes. The samples were then examined by the scanning electron microscope.

STATISTICAL ANALYSIS USED

The statistical analysis was carried out using Statistical Package for Social Sciences (SPSS Inc., Chicago, IL, version 15.0 for Windows). For all quantitative variables means and standard deviations were calculated and compared. For more than two groups ANOVA was applied. For multiple comparisons post hoc tests with Bonferroni correction was used.

RESULTS

Upon statistical analysis the root conditioning agents used in this study were found to be effective in removing the smear layer, uncovering and widening the dentin tubules and unmasking the dentin collagen matrix.

CONCLUSION

Tetracycline HCl was found to be the best root conditioner among the three agents used.

Debris and smear layer removal efficacy and changes in morphology of dentinal tubules after using citric acid, tetracycline-hydrochloride and mixture of tetracycline and acid and detergent

Background:

In periodontal diseases, contamination of roots with bacteria and their active biologic agents and smear layer formation following periodontal treatments, prevents reattachment of periodontal cells. As a matter of fact biomodification of root surface and removal of smear layer and debris is critical for regeneration of periodontal structures. The aim of this study was to compare the efficacy of smear layer removal by citric acid, tetracycline-hydrochloride (TTC-HCL) and mixture of tetracycline and acid and detergent (MTAD).

Materials and Methods:

In this in vitro and experimental study, 12 impacted third molars were sectioned from cervical enamel junction (CEJ) to mid-root area into four dentinal specimens (n = 48). Three groups were conditioned by citric acid 3%, TTC-HCL 50 mg/mL and MTAD by means of cotton pellets, which were changed every 30 s for 3 min. The control group was conditioned by distilled water. Images from scanning electron microscope (SEM) were examined by two different analyzers. Data was analyzed by Kroskal Wallis and Mann–Whitney statistical analysis.

Results:

The mean of dentinal tubules diameter was the most in MTAD group and the least in TTC-HCL and this difference was statistically significant (P = 0.05).

Conclusion:

According to the present study, TTC-HCL could remove debris and smear layer but citric acid and MTAD had better debris and smear layer removal efficacy and demineralization effect in comparison with TTC-HCL.

Bone regeneration using porous titanium particles versus bovine hydroxyapatite: a sinus lift study in rabbits

AIM

The first objective of this study was to qualitatively and quantitatively assess the bone formation process, particularly the long-term behavior and three-dimensional volume stability of subsinusal bone regeneration, using titanium (Ti) or bovine hydroxyapatite (BHA) granules, in a rabbit model. The second objective was to evaluate the effect of the hydration of the BHA particles with a therapeutic concentration of doxycycline solution on the osteogenesis and biomaterial resorption.

MATERIALS AND METHODS

Rabbits underwent a double sinus lift procedure using one of three materials: grade 1 porous Ti particles, BHA, or BHA hydrated with doxycycline solution (0.1mg/ml) (BHATTC). Animals were sacrificed after 1 week, 5 weeks, or 6 months. Samples were analyzed using µCT and nondecalcified histology.

RESULTS

The materials used in each of the three groups allowed an optimal bone formation; bone quantities and densities were not statistically different between the three groups. At 6 months, more stable three-dimensional volume stability was found with Ti and BHATTC (p=.0033). At 5 weeks and 6 months, bone to material contact corroborating osteoconduction was significantly higher with BHA and BHATTC than with Ti (p<.0001).

CONCLUSIONS AND CLINICAL IMPLICATIONS

Even though the studied biomaterials displayed different architectures, they are relevant candidates for sinus lift bone augmentation prior to dental implants because they allow adequate three-dimensional stability and osteogenesis. However, to recommend the clinical use of Ti, both an observation on the drilling effects of Ti particles and clinical trials are needed.

[Scanning electron microscopy analysis on root surfaces before and after scalling and citric acid and EDTA conditioning: an "in vitro" study]

The most benefic root surface for periodontal regeneration has not been known. Looking for this surface this study used 14 human teeth prepared as testing corpus and treated with scaling and conditioning with citric acid and EDTA, and analysed in scanning electron microscopy. The health teeth surfaces showed regular grains representing broken periodontal ligament fibers by exodontics. The contaminated surfaces showed calculus masses, very porous, and resorption areas. When scalled with hand curettes the surfaces was covered by smear layer. The citric acid conditioning was efficient on smear layer removal, as well as the EDTA gel, and the EDTA liquid solution was not efficient on smear removal.

In vitro response of human gingival epithelioid S-G cells to minocycline

Minocycline, a broad-spectrum antibiotic used in the treatment of acne and periodontal disease and to control inflammatory diseases such as rheumatoid arthritis, has recently been shown to induce a spectrum of adverse health effects. In the light of these contradictory data, this research was directed to provide basic information on the toxicology of minocycline, using in vitro cell culture models, and to evaluate its efficacy in periodontal therapies, particularly for wound healing. The human gingival epithelioid S-G cell line was used as the bioindicator. The greater toxicity of minocycline over doxycycline and tetracycline, related antimicrobial agents, probably correlated with its higher lipophilicity. The cytotoxicity of minocycline was unaffected by an S9 hepatic microsomal fraction, indicating that it is a direct-acting, rather than a metabolism-mediated, cytotoxicant. In comparative toxicity studies, much variation in the degree of sensitivity to minocycline was noted for different cell types. No correlation in the extent of sensitivity to minocycline and the physiologic state of the bioindicator cell (normal, transformed or malignant) was noted. The toxicity of minocycline to the S-G cells was dependent on its concentration and length of exposure. For a continuous 3-day exposure of the S-G cells to minocycline, the midpoint cytotoxicity (or, NR(50)) value, as quantified in the neutral red (NR) assay, was 204 microg/ml on day 1, 84 microg/ml on day 2, and 59 microg/ml on day 3. For a 1-h exposure of the S-G cells in phosphate buffered saline (PBS), the NR(50) value was 780 microg/ml minocycline. Although a 1-h exposure in PBS to 200 microg/ml minocycline exerted some toxicity, the S-G cells recovered on exposure to growth medium; irreversible, progressive damage occurred at 400 microg/ml minocycline and greater. Minocycline, at 50 microg/ml, enhanced attachment of the S-G cells to a gelatin-coated surface and cell migration towards an immobilized fibronectin gradient, both biologic parameters important in periodontal wound healing. Minocycline generally had little or no effect on production of the pro-inflammatory cytokines, interleukin-6 (IL-6) and interleukin-8 (IL-8), by non-activated S-G cells, the exception being stimulation of IL-6 at 48 h. IL-1beta, however, greatly stimulated IL-6 and IL-8 production, which was further increased by concurrent exposure to minocycline. This suggested that minocycline may enhance the ability of gingival epithelial cells to participate in the early, inflammatory phase of periodontal wound healing. The limitation of minocycline efficacy to a rather narrow window of concentration, centering about 50 microg/ml, and primarily for short-term exposures may possibly explain, in part, the contradictory clinical data on the health effects of this drug.

Pluronic polyol effects on human gingival fibroblast attachment and growth

BACKGROUND

Enhanced speed of human gingival fibroblast (HGF) spreading and attachment, as affected by ionic bonding interactions, may facilitate cell orientation and subsequent collagen synthesis to promote early wound healing. The purpose of this study was to determine the in vitro effects of pluronic polyols, a family of widely used surfactants currently used as drug carriers for antibiotic, anti-inflammatory, and anti-neoplastic agents, on the attachment and growth of human gingival fibroblasts (HGF) to dentin and plastic surfaces using established tissue culture techniques.

METHODS

Plastic culture wells containing Eagle's minimal essential media (EMEM) with 10% fetal calf serum and Pluronic F-68 or F-127 in concentrations from 1.2 x 10(-2) to 1.2 x 10(-10) M were incubated with HGF and run in replicates of ten. Attached cells were quantified by measuring the optical density of methylene blue-stained cells. Additional experiments were conducted using human dentin sections as a substrate and Pluronic F-68 or F-127 at a concentration of 1.2 x 10(-8) M. In these experiments, HGF were stained with acridine orange and quantified per unit area of dentin by fluorescence microscopy.

RESULTS

Attachment and growth of HGF to both plastic and dentin were significantly increased over serum controls by very low concentrations of Pluronic F-68 and F-127 by 30 minutes, with attachment reaching a plateau at 2 hours.

CONCLUSIONS

Pluronic polyols, a family of widely used surfactants, in very low dosages may be beneficial in early postsurgical wound healing by facilitating early attachment and enhancing the growth rate of human gingival fibroblasts.