Effect of a ceramic and a non-ceramic hydroxyapatite on cell growth and procollagen synthesis of cultured human gingival fibroblasts

Mechanical Properties and In Vitro Biocompatibility of Hybrid Polymer-HA/BAG Ceramic Dental Materials

The aim of this study is to prepare hybrid polymer-ceramic dental materials for chairside computer-aided design/computer-aided manufacturing (CAD/CAM) applications. The hybrid polymer-ceramic materials were fabricated via infiltrating polymerizable monomer mixtures into sintered hydroxyapatite/bioactive glass (HA/BAG) ceramic blocks and thermo-curing. The microstructure was observed by scanning electron microscopy and an energy-dispersive spectrometer. The phase structure was analyzed by X-ray diffraction. The composition ratio was analyzed by a thermogravimetric analyzer. The hardness was measured by a Vickers hardness tester. The flexural strength, flexural modulus, and compressive strength were measured and calculated by a universal testing machine. The growth of human gingival fibroblasts was evaluated by a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) colorimetric assay and immunofluorescence staining. The results showed that the sintering temperature and BAG content affected the mechanical properties of the hybrid polymer-ceramic materials. The X-ray diffraction analysis showed that high-temperature sintering promoted the partial conversion of HA to β-tricalcium phosphate. The values of the hardness, flexural strength, flexural modulus, and compressive strength of all the hybrid polymer-ceramic materials were 0.89-3.51 GPa, 57.61-118.05 MPa, 20.26-39.77 GPa, and 60.36-390.46 MPa, respectively. The mechanical properties of the hybrid polymer-ceramic materials were similar to natural teeth. As a trade-off between flexural strength and hardness, hybrid polymer-ceramic material with 20 wt.% BAG sintered at 1000 °C was the best material. In vitro experiments confirmed the biocompatibility of the hybrid polymer-ceramic material. Therefore, the hybrid polymer-ceramic material is expected to become a new type of dental restoration material.

Histologic Evaluation of Soft Tissues around Dental Implant Abutments: A Narrative Review

The basis for dental implant success comes not only with the titanium implant osseointegration but also depends on other factors such as the development of a soft tissue barrier, which protects the peri-implant bone from the oral environment. The characteristics of surfaces in contact with peri-implant soft tissues may affect the capacity of peri-implant mucosal cells to create a tight seal around the implant, thus influencing long-term implant success. Many histological studies on animals have been conducted on different materials to better understand their influence on peri-implant soft tissues, with the limitation that results from animal studies cannot be fully translated in humans. The aim of this review paper was to analyze the literature focusing on histological clinical studies in humans which have examined different materials or different surface treatments and their effects on peri-implant soft tissues. The research was conducted according to the following PICO question: “Do different implant/abutment materials affect peri-implant soft tissues adhesion and health?”. Nine articles were analyzed in this review. The results of this review show the influence of different abutment materials on the peri-implant soft tissues, and the need of further research regarding the effect that abutment materials, surface treatments, and surface properties have on soft tissues.

Graphene oxide and mineralized collagen-functionalized dental implant abutment with effective soft tissue seal and romotely repeatable photodisinfection

Grasping the boundary of antibacterial function may be better for the sealing of soft tissue around dental implant abutment. Inspired by ‘overdone is worse than undone’, we prepared a sandwich-structured dental implant coating on the percutaneous part using graphene oxide (GO) wrapped under mineralized collagen. Our unique coating structure ensured the high photothermal conversion capability and good photothermal stability of GO. The prepared coating not only achieved suitable inhibition on colonizing bacteria growth of Streptococcus sanguinis, Fusobacterium nucleatum and Porphyromonas gingivalis but also disrupted the wall/membrane permeability of free bacteria. Further enhancements on the antibacterial property were generally observed through the additional incorporation of dimethylaminododecyl methacrylate. Additionally, the coating with sandwich structure significantly enhanced the adhesion, cytoskeleton organization and proliferation of human gingival fibroblasts, which was effective to improve soft tissue sealing. Furthermore, cell viability was preserved when cells and bacteria were cultivated in the same environment by a coculture assay. This was attributed to the sandwich structure and mineralized collagen as the outmost layer, which would protect tissue cells from photothermal therapy and GO, as well as accelerate the recovery of cell activity. Overall, the coating design would provide a useful alternative method for dental implant abutment surface modification and functionalization.

Development of an Experimental Dentifrice with Hydroxyapatite Nanoparticles and High Fluoride Concentration to Manage Root Dentin Demineralization

Background

High-fluoride dentifrice is used to manage root caries, but there is no evidence whether its association with nanohydroxyapatite could provide an additional protection for root caries. Therefore, this study aimed to develop and evaluate the effect of an experimental dentifrice with high fluoride (F⁻) concentration and nanohydroxyapatite (nano-HA) on root dentin demineralization.

Materials and Methods

After formulation of dentifrices, root dentin specimens were randomly assigned to six groups (n = 10) using different dentifrice treatments: placebo; nano-HA without F⁻; 1,100 µg F⁻/g; 1,100 µg F⁻/g + nano-HA; 5,000 µg F⁻/g; and 5,000 µg F⁻/g + nano-HA. A pH cycling model was performed for 10 days, in which treatments were performed twice a day. After that period, the longitudinal hardness was evaluated and the area of demineralization (ΔS) was calculated. The formulated dentifrices were evaluated for primary stability, cytotoxicity, and other technical parameters. Two-way ANOVA and Tukey’s test with p set at 5% were used for data analysis.

Results

The experimental dentifrices were stable and had no cytotoxicity. Regarding dentin demineralization, the placebo group significantly increased ΔS compared to all other treatment groups (p<0.001). The dentifrices containing 5,000 µg F⁻/g, regardless of the presence of nano-HA, led to a smaller lesion area in relation to the other treatments (p<0.001).

Conclusion

The findings of this study suggest that nano-HA reduced dentin demineralization, and dentifrice with 5,000 µg F⁻/g dentifrices, regardless of the presence of nano-HA, showed a greater reduction in root dentin demineralization.

Chiral Tartaric Acid Improves Fracture Toughness of Bioactive Brushite-Collagen Bone Cements

Brushite cements are promising bone regeneration materials with limited biological and mechanical properties. Here, we engineer a mechanically improved brushite-collagen type I cement with enhanced biological properties by use of chiral chemistry; d- and l-tartaric acid were used to limit crystal growth and increase the mechanical properties of brushite-collagen cements. The impact of the chiral molecules on the cements was examined with Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). A 3-point bend test was utilized to study the fracture toughness, and cell attachment and morphology studies were carried out to demonstrate biocompatibility. XRD and SEM analyses showed that l-, but not d-tartaric acid, significantly restrained brushite crystal growth by binding to the {010} plane of the mineral and increased brushite crystal packing and the collagen interaction area. l-Tartaric acid significantly improved fracture toughness compared to traditional brushite by 30%. Collagen significantly enhanced cell morphology and focal adhesion expression on l-tartaric acid-treated brushite cements.

BIOMATERIAL IMPLANTS IN BONE FRACTURES PRODUCED IN RATS FIBULAS

To evaluate the importance of collagen and hydroxyapatite in the regeneration of fractures experimentally induced in the fibulas of rats. Method: 15 rats were used. These were subjected to surgery to remove a fragment from the fibula. This site then received a graft consisting of a silicone tubes filled with hydroxyapatite and collagen. Results: Little bone neoformation occurred inside the tubes filled with the biomaterials. There was more neoformation in the tubes with collagen. Conclusion: The biomaterials used demonstrated biocompatibility and osteoconductive capacity that was capable of stimulating osteogenesis, even in bones with secondary mechanical and morphological functions such as the fibula of rats.

Cytotoxicity, genotoxicity and antibacterial effectiveness of a bioceramic endodontic sealer

AIM

To compare the characteristics of bioceramic endodontic sealer Endosequence BC sealer with those of AH Plus sealer.

METHODOLOGY

Cytotoxicity and genotoxicity were analysed on human gingival fibroblasts submitted to cell culture medium conditioned by sealers using the MTT reduction assay and micronucleus formation test (MNT), respectively. Cells grown on fresh medium served as controls. Cell viabilities were measured at 1, 3, 5 and 7 days. The antibacterial activity was analysed on an Enterococcus faecalis strain (ATCC 29212) using both on agar diffusion test (ADT) and a direct contact test (DCT). The inhibition zones in ADT were measured after 48 h and the colony-forming units counting in the DCT after 1, 24, 72 and 168 h. Data were compared by anova and Tukey's test and MNT by Fisher's exact test (P < 0.05).

RESULTS

Cultures submitted to Endosequence BC sealer had a significantly higher number of viable cells (P < 0.01) and less micronucleus formation (P < 0.05) than AH Plus sealer. Endosequence BC sealer exhibited significantly smaller inhibition zones (6.00 ± 0.03 mm) than AH Plus sealer (10.31 ± 0.21 mm) (P < 0.05). Moreover, Endosequence BC sealer had significantly smaller antibacterial activity than AH Plus sealer up to 1 h of direct contact (P < 0.05). On other exposure times, both materials had similar antibacterial effectiveness (P > 0.05).

CONCLUSIONS

Bioceramic-based sealer had less cytotoxicity and genotoxicity and similar antibacterial effect against E. faecalis in comparison with AH Plus sealer.

Relationship between toothpastes properties and patient-reported discomfort: crossover study

OBJECTIVES

This study aims to correlate patient-reported reactions with in vitro analyses of the pH, abrasive quality, and cytotoxicity of four toothpastes.

MATERIALS AND METHODS

One hundred twenty-one patients received non-identified samples of toothpaste to be used for 6 days and answered a questionnaire about their sensations. In vitro analysis: the pH of toothpastes was measured with a pH meter. The abrasivity of toothpastes was evaluated against composite resin specimens (n = 10). A toothbrushing machine was used to simulate wear, which was indirectly measured by mass loss using a scale. Cell culture media conditioned with toothpaste were used to assess the cytotoxicity. Confluent cells were kept in contact with the conditioned media or control for 24 h. The cell viability was measured using the 3-(bromide, 4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium (MTT)-reduction assay. The obtained data on the pH, weight loss, and cell viability were compared by ANOVA/Tukey's tests (p < 0.05).

RESULTS

With the exception of the bleaching effect paste, the Oral B® paste produced the highest frequencies of irritation reports, tooth sensitivity, taste discomfort, and texture discomfort in the clinical study; patients also reported rougher teeth, soft tissue peeling, dry mouth, thrush, tingling, and taste changes in response to this paste. The in vitro analysis demonstrated that Oral B® had the lowest pH, the highest abrasivity, and produced the lowest cell viability (p < 0.01).

CONCLUSION

Results suggest that low pH toothpastes that are highly abrasive and cytotoxic may cause undesirable reactions in patients.

CLINICAL RELEVANCE

Toothpaste's properties should be well known for indication to patient therefore minimizing discomfort reports.

Choice of toothpaste for the elderly: an in vitro study

Hyposalivation and dental root exposure in the elderly are problems that require special oral care. In this context, the characteristics of certain toothpastes are of particular importance. Thus, the aim of this study was to evaluate the cytotoxicity and dentin wear caused by seven different toothpastes. For dentin wear analysis, 40 root dentin specimens were submitted to 20,000 brushing cycles with the different toothpastes and distilled water (control group-CG), using a brushing machine. Dentin surface loss (SL) was measured by contact profilometer. The cytotoxicity of each toothpaste was tested using cultured fibroblasts submitted to a cell-culture-conditioned medium. Fresh medium served as the control. Cell viability was assessed by MTT assay after 24 h of contact with the conditioned media. The data were analyzed statistically by ANOVA, followed by Tukey's test (p < 0.05). The SL of the CG was minimal and significantly lower than that of the Oral B Pro Health (OBPH) group (p < 0.05). All other groups presented SL in between that of the CG and the Oral B Pro Health OBPH group, except for the Sensodyne (SEN) group, which presented SL similar to that of CG (p = 0.05). The SEN group presented a percentage of viable cells similar to that of CG: between 60-89%. All the other toothpastes showed high cytotoxicity, with cell viability less than 50% of the CG. Considering study limitations, we concluded that only one of the seven tested toothpastes exhibited the most desirable toothpaste characteristics for the worldwide growing elderly population (e.g. low cytotoxicity and low-abrasive potential).

Analysis in vitro of the cytotoxicity of potential implant materials. I: Zirconia-titania sintered ceramics

Zirconia (ZrO2) is a bioinert, strong, and tough ceramic, while titania (TiO2) is bioactive but has poor mechanical properties. It is expected that ZrO2-TiO2 mixed ceramics incorporate the individual properties of both ceramics, so that this material would exhibit better biological properties. Thus, the objective of this study was to compare the biocompatibility properties of ZrO2-TiO2 mixed ceramics. Sintered ceramics pellets, obtained from powders of TiO2, ZrO2, and three different ZrO2-TiO2 mixed oxides were used. Roughnesses, X-ray diffraction, microstructure through SEM, hardness, and DRIFT characterizations were performed. For biocompatibility analysis cultured FMM1 fibroblasts were plated on the top of disks and counted in SEM micrographs 1 and 2 days later. Data were compared by ANOVA complemented by Tukey's test. All samples presented high densities and similar microstructure. The H2O content in the mixed ceramics was more evident than in pure ceramics. The number of fibroblasts attached to the disks increased significantly independently of the experimental group. The cell growth on the top of the ZrO2-TiO2 samples was similar and significantly higher than those of TiO2 and ZrO2 samples. Our in vitro experiments showed that the ZrO2-TiO2 sintered ceramics are biocompatible allowing faster cell growth than pure oxides ceramics. The improvement of hardness is proportional to the ZrO2 content. Thus, the ZrO2-TiO2 sintered ceramics could be considered as potential implant material.

Preparation and characterization of calcium phosphate biomaterials

Calcium phosphate cement (CPC) samples have been prepared with a mixture of monocalciumphosphate monohydrate (MCPM) and calcium carbonate (CC) powders, in stechiometric moles ratio 1:2.5 to obtain a Ca/P ratio of about 1.67 typical of hydroxyapatite (HAp), with or without addition of HAp. All specimens are incubated at 30 degrees C in a steam saturated air environment for 3, 6 and 15 days respectively, afterwards dried and stored under nitrogen. The calcium phosphate samples have been characterized by X-ray diffraction (XRD), Vickers hardness test (HV), diametral compression (d.c.), strength compression, and porosity evaluation. MCPM/CC mixture has a 30% HAp final concentration and is characterized by higher porosity (amount 78%) and mechanical properties useful as filler in bone segments without high mechanical stress.

Effect of Er:YAG Laser Combined With rhPDGF-BB on Attachment of Cultured Fibroblasts to Periodontally Involved Root Surfaces

BACKGROUND

The use of the erbium-doped:yttrium, aluminum, and garnet (Er:YAG) laser in periodontal therapy has been the focus of much research. Recombinant human platelet-derived growth factor-BB (rhPDGF-BB) is suggested as a potent stimulator and strong mitogen for human periodontal ligament cells. The present study tested the direct effects of Er:YAG laser irradiation, alone or with rhPDGF-BB application, on the biocompatibility of periodontally diseased roots through fibroblast attachment and proliferation.

METHODS

The study examined five healthy and 15 periodontally involved teeth, prepared from proximal surfaces, which were divided randomly into four groups (10 specimens each): group 1: healthy; group 2: untreated diseased; group 3: Er:YAG laser irradiation (60 mJ/pulse, 10 Hz); and group 4: Er:YAG laser irradiation (60 mJ/pulse, 10 Hz) plus rhPDGF-BB application (50 ng/ml). Three subgroups per group (three specimens each) were incubated for three periods (1, 3, or 7 days). The remaining specimen was used to determine surface topography. Fibroblasts were pooled on root specimens and incubated. Results were evaluated using scanning electron microscopy. Repeated cell counts were performed within a representative standard area.

RESULTS

Using paired t tests, all experimental groups (except group 2 diseased) showed statistically significant differences between 1- and 3-day and between 1- and 7-day incubation periods, but not between 3- and 7-day incubation periods. Using analysis of variance, the intergroup comparison showed significant differences favoring group 1 over groups 2 and 3 and group 4 over group 2 at the 1-day incubation period; group 1 was favored over groups 2, 3, and 4 and groups 3 and 4 were favored over group 2 at the 3- and 7-day incubation periods. Comparable effects were shown between groups 3 and 4 for all incubation periods and between groups 2 and 3 and groups 1 and 4 for the 1-day incubation.

CONCLUSIONS

Er:YAG laser used alone or in combination with rhPDGF-BB application may offer a promising periodontal therapy for conditioning root surfaces, although the combined application seemed to be slightly more effective. However, testing laser use in intervals and with parameters <60 mJ/pulse and 10 Hz is required to verify the minimum threshold values necessary to obtain complete root debridement and clarify optimal conditions for fibroblast cell attachment and growth. Further studies are needed to determine ideal parameters for creating the best environment for successful periodontal treatment.

Use of hydroxyapatite in tooth replantation radiographically followed up for 14 years: a case report

A lateral incisor was replanted 4 h after trauma. The tooth subsequently developed external root resorption treated with calcium hydroxide initially and with a hydroxyapatite root filling subsequently. Radiographs of the replanted tooth were obtained to follow up the patient for 14 years.

Effect of low-power laser irradiation on protein synthesis and ultrastructure of human gingival fibroblasts

BACKGROUND AND OBJECTIVES

Low-power lasers improve wound healing. Cell proliferation and protein secretion are important steps of this process. The aim of this study was to analyze both protein synthesis and ultrastructural morphology of human gingival fibroblasts irradiated by a low-power laser.

STUDY DESIGN/MATERIALS AND METHODS

The cell line FMM1 was grown in nutritional deficit. Laser irradiation was carried out with a gallium-aluminum-arsenate (Ga-Al-As) diode laser (904 nm, 120 mW, energy density of 3 J/cm(2)). The protein synthesis analysis and ultrastructural morphology of control (non-irradiated) and irradiated cultures were obtained.

RESULTS

There were changes in the structure of cytoplasm organelles of treated cells. The procollagen was not altered by the laser irradiation; however, there were a significant reduction of the amount of protein in the DMEM conditioned by irradiated cells.

CONCLUSIONS

Low-power laser irradiation causes ultrastructural changes in cultured fibroblasts. We suggest that these alterations may lead to disturbances in the collagen metabolism.

Adhesion and growth of cultured human gingival fibroblasts on periodontally involved root surfaces treated by Er:YAG laser

BACKGROUND

The application of Er:YAG laser irradiation, approved in 1997 to be used on dental hard tissues, has been investigated for periodontal therapy. The aim of this study was to analyze the biocompatibility of root surfaces treated by Er:YAG laser.

METHODS

Adhesion and growth of cultured human gingival fibroblasts on root surfaces treated by either irradiation with Er:YAG laser or curet were compared. Thirty single-rooted teeth extracted because of periodontal disease were used. Calculus deposits on all experimental surfaces were removed, and the teeth were divided into three groups according to the applied treatment: group A, root planing with Gracey curet no. 3/4; group B, two irradiations with laser (60 mJ/pulse, 10 Hz; 10" each with 10-second interval, 3 J/cm2); group C, two irradiations with laser (100 mJ/pulse, 10 Hz; 10" each with 10-second interval, 5 J/cm2). Fragments (5 mm x 6 mm) were obtained from the experimental surfaces. Then, 1 x 10(3) cells were seeded on the top of each fragment. One, 2, and 3 days after seeding the specimens were prepared for scanning electron microscopy analysis, and the cells on the electronmicrographs were counted. The data obtained in triplicate were statistically compared by the Kruskall-Wallis test complemented by the Dunn test (P < or = 0.05).

RESULTS

Human gingival fibroblasts adhered to and grew on all treated surfaces. Group B presented a significantly higher cell count than did the other two groups at days 1 and 2. Three days after seeding the cultured fibroblasts of groups A and B reached total confluence. The cell count of group B was significantly higher than that of group C.

CONCLUSION

The surfaces treated with 60 mJ/pulse Er:YAG laser irradiation promoted faster adhesion and growth than surfaces treated with either root planing or 100 mJ/pulse Er:YAG laser irradiation.

Evaluation of the titanium Ti-6Al-7Nb alloy with and without plasma-sprayed hydroxyapatite coating on growth and viability of cultured osteoblast-like cells

BACKGROUND

Osseointegrated dental implants are currently recognized as a standard treatment method in dentistry. Titanium (Ti) and its alloys are the metals of choice for endosseous parts of currently available dental implants. Ti-6Al-4V is the most used Ti alloy, however; an improved version, Ti-6Al-7Nb, has been recently developed.

METHODS

Rat osteoblast-like cells (osteo- 1 culture) were used to analyze the biocompatibility of Ti-6Al-7Nb alloy with and without hydroxyapatite (HA) coating. The cells were grown on culture Petri dishes on the top of either plain Ti-6Al-7Nb or HA-coated Ti-6Al-7Nb disks. Osteo-1 cells grown on plain culture dishes were used as controls. Growth and cell viability curves were obtained by scanning electron microscopy. For the growth and viability curves, 10(4) cells were seeded on 35 mm dishes. Cells from each group were counted, in triplicate at 3, 7, 11, and 15 days after seeding using the Trypan blue dye exclusion assay.

RESULTS

The cells grew as multiple layers on both Ti-6Al-7Nb substrates, showing extracellular matrix only when grown on HA-coated Ti-6Al-7Nb disks. The cells grown on HA-coated Ti-6Al-7Nb grew more slowly than the other 2 groups, with significantly smaller cell numbers than control cultures at the end of the experimental time. Additionally, the HA coated Ti-6Al-7Nb group presented smaller percentage of cell viability when compared to the control group. However, no significant differences were observed between the Ti groups.

CONCLUSIONS

The presence of HA on the Ti-6Al-7Nb surface impaired the cell growth and viability of osteo-1 cells. However, this coating improved the extracellular matrix formation. Thus, our cell viability and structural studies showed that Ti-6Al-7Nb with or without HA coating has relevant physical and biological properties as an implant material.

Multi-layered microcapsules for cell encapsulation

Mechanical stability, complete encapsulation, selective permeability, and suitable extra-cellular microenvironment, are the major considerations in designing microcapsules for cell encapsulation. We have developed four types of multi-layered microcapsules that allow selective optimization of these parameters. Primary hepatocytes were used as model cells to test these different microcapsule configurations. Type-1 microcapsules with an average diameter of 400 microm were formed by complexing modified collagen with a ter-polymer shell of 2-hydroxyethyl methylacrylate (HEMA), methacrylic acid (MAA) and methyl methacrylate (MMA), resulting in a capsule thickness of 2-5 microm. Cells in these microcapsules exhibited improved cellular functions over those cultured on collagen monolayers. Type-II microcapsules were formed by encapsulating the Type-I microcapsules in another 2-5 microm ter-polymer shell and a approximately 5 microm collagen layer between the two ter-polymer shells to ensure complete cell encapsulation. Type-II microcapsules comprised of a macro-porous exoskeleton with materials such as alumina sol-gel coated on the Type-I microcapsules. Nano-indendation assay indicated an improved mechanical stability over the Type-I microcapsules. Type-IV microcapsules were created by encapsulating Type-III microcapsules in another 2-5 microm ter-polymer shell, with the aim of imparting a negatively charged smooth surface to minimize plasma protein absorption and ensure complete cell encapsulation. The permeability for nutrient exchange, cellular functions in terms of urea production and mechanical stability of the microcapsules were characterized. The advantages and limitations of these microcapsules for tissue engineering are discussed.

Cytotoxic effects of 10% citric acid and EDTA-T used as root canal irrigants: an in vitro analysis

EDTA-T and 10% citric acid used as root canal irrigants lead to more visible dentinal tubules than 5% sodium hypochlorite associated with 3% hydrogen peroxide. However, these cleansing agents must be compatible with apical periodontal tissue. We analyzed the cytotoxicity of 10% citric acid and EDTA-T in cultured fibroblasts using Trypan blue. The solutions were diluted to 1%, 0.1%, and 0.01% and applied to NIH 3T3 cell cultures. Cells grown on fresh DMEM served as a control. After 0, 6, 12, and 24 h (short-term assay, viability) and 1, 3, 5, and 7 days (long-term assay, survival), the cells were counted using a hemocytometer. In short-term tests, cell viability ranged from 85% to 99% for all experimental groups with no statistical differences when compared with control cultures, except for the group treated with 1% EDTA-T, which caused a progressive decrease in cell viability. In long-term tests, all cultures increased in number from day 1 to the end of the experimental period, showing no inhibition of cell proliferation, except for the cultures treated with 1% EDTA-T, which totally prevented cell growth. All dilutions of 10% citric acid were more biocompatible than EDTA-T. Cultures treated with citric acid had a higher percentage of viable cells in the short-term assays, and the cells retained their self-renewal capacity.

Comparison of the low level laser therapy effects on cultured human gingival fibroblasts proliferation using different irradiance and same fluence

BACKGROUND AND OBJECTIVE

The low level laser therapy (LLLT) has been used in Dentistry to improve wound healing. In order to analyse the effect of LLLT on the in vitro proliferation of gingival fibroblasts we developed a primary culture of human gingival fibroblasts.

STUDY DESIGN/MATERIALS AND METHODS

The cell line named LMF was grown in Dulbecco's Modified Eagle's medium (DME) with either 5% (nutritional deficit) or 10% fetal bovine serum (fbs). Laser irradiation was carried out with diode lasers with the following wavelengths: 670 nm (L1), 780 nm (L2), 692 nm (L3), and 786 nm (L4). The fluence was fixed in 2 J/cm(2). For growth analysis, control (not irradiated) and treated cultures (irradiated) were plated in 60 mm diameter culture dishes for 12 h before the irradiation.

RESULTS

We found that cells cultured in nutritional deficit condition grown in medium supplemented by only 5% fbs presented a cell proliferation rate significantly smaller that cell grown in ideal culture conditions (10% fbs). However, when irradiated, cells in nutritional deficit presented cell growth similar or higher than that of control cells grown in ideal culture conditions. Using the same fluence, the infrared laser induced a higher cell proliferation than visible laser when the power outputs were different. However, lasers of equal power output presented similar effect on cell growth independently of their wavelengths.

CONCLUSIONS

The LLLT acts by improving the in vitro fibroblast proliferation and a smaller laser exposure time results in higher proliferation.

Histopathological morphometric evaluation of 2 different hydroxyapatite-bone derivatives in sinus augmentation procedures: a comparative study in humans

BACKGROUND

Xenografts to augment the maxillary sinus have been used extensively. The aim of the present study was to evaluate, qualitatively and quantitatively, two different HA derivatives of natural and synthetic sources on newly formed bone in the augmented sinus.

METHODS

A bilateral sinus augmentation procedure with simultaneous (16 out of 20 sites) or subsequent implant placement was performed in 10 patients. The antrum was randomly filled with a deproteinized, bovine hydroxyapatite mineral (B-HA) on one side and a non-ceramic resorbable hydroxyapatite (NC-HA) on the other. Cylindrical specimens were harvested from the augmented core at 12 months. Decalcified specimens were sectioned at a cross-horizontal plane and stained with hematoxylin and eosin for histopathologic and histomorphometric examinations. Tissue area fractions of bone, marrow, and the grafted particles were calculated for each specimen from the lateral to the deep region, and changes in values were compared within each material and between them.

RESULTS

New bone formation was evident. B-HA and NC-HA particles were observed in all specimens surrounded by newly formed bone in direct connection or by soft tissue marrow. Morphometrically in the B-HA sites, from the lateral to deeper area, bone area fraction increased from 29.8% to 54.2% (average 42.1%) and marrow area fraction decreased from 37.9% to 26.7% (average 33.3%). The mineral area fraction decreased from 32.3% to 19.1% (average 24.7%). All increasing/decreasing patterns were statistically significant (P < 0.001). In the NC-HA sites, from the lateral to deeper area, bone area fraction increased from 25% to 36.5% (average 32.3%) and marrow area fraction decreased from 51.6% to 41.9% (average 43.2%) (P <0.001). The mineral area fraction decreased from 29% to 21.7% (average 24.6%) (P = 0.038). Comparison between the two HA derivative groups showed a significant difference between the bone area fraction averages (P = 0.0053) and between the increasing patterns along the core depth (P = 0.0006). There was also a significant difference between the decreasing marrow patterns (P = 0.003), but not between their averages. Comparison between the mineral area fractions showed no differences.

CONCLUSIONS

B-HA and NC-HA were proven to be biocompatible materials. Although the B-HA-augmented sites showed a higher percentage of bone formation at 12 months, both are suitable bone derivatives in sinus augmentation procedures and can accommodate osseointegrated implants.