Effect of antibacterial photodynamic therapy with chitosan nanoparticles on Aggregatibacter actinomycetemcomitans

BACKGROUND

This study aimed to assess the effect of antibacterial photodynamic therapy (aPDT) with chitosan nanoparticles on Aggregatibacter actinomycetemcomitans (A. actinomycetemcomitans) in the culture medium.

MATERIALS AND METHODS

In this in vitro, experimental study, chitosan nanoparticles (CHNPs) containing indocyanine green (ICG) were first synthesized and characterized. A. actinomycetemcomitans was cultured on trypticase soy agar. The culture media containing A. actinomycetemcomitans were randomly subjected to the following six decontamination protocols: negative control subjected to sterile phosphate buffered saline (PBS) for 5 min, positive control exposed to 0.2 % chlorhexidine (CHX) for 5 min, exposure to 0.25 mg/mL ICG in the dark at 37 °C for 5 min, aPDT with 0.25 mg/mL ICG and diode laser (808 nm, 250 mW, 14.94 J/cm2, 30 s, 1 mm distance, 8 mm tip diameter), exposure to CHNPs containing 0.25 mg/mL ICG in the dark at 37 °C for 5 min, and aPDT with CHNPs containing 0.25 mg/mL ICG and diode laser. The number of colonies was counted, and analyzed by one-way ANOVA and Tamhane test (alpha=0.050).

RESULTS

Antimicrobial PDT with CHNPs, and CHX groups comparably showed the highest decontamination efficacy (P = 0.000).

CONCLUSION

The results showed optimal efficacy of aPDT with CHNPs containing 0.25 mg/mL ICG and 808 nm diode laser for reduction of A. actinomycetemcomitans colony count. Thus, aPDT appears to be as effective as CHX, but with fewer adverse effects.

An in vitro study on the effects of photobiomodulation by diode lasers (red, infrared, and red-infrared combination) on periodontal ligament mesenchymal stem cells treated with bisphosphonates

This study evaluated the effect of photobiomodulation therapy (PBMT) using 660 and 808 nm diode lasers (individual and in combination) on periodontal ligament mesenchymal stem cells (PDLSCs) in the presence of zoledronic acid (ZA). PDLSCs were cultured for 48 h in DMEM complete medium containing 5 μM ZA. PBMT was done three times with a 24-h interval in groups 1 (660 nm, 5 J/cm2 ), 2 (880 nm, 3 J/cm2 ), and 3 (660 + 808 nm) either in normal or ZA-treated culture medium. Control groups did not receive PBMT. Twenty-four hours post-irradiation, cell proliferation and expression of RANKL and OPG were assessed using MTT and real-time PCR tests, respectively. The results showed a significant decrease in cell viability in ZA-treated cells (p < 0.001). Additionally, ZA induced the expression of OPG (p = 0.03) while reducing RANKL (p < 0.001). Cell proliferation was significantly increased in 808 and 660 + 808 nm groups. Moreover, all PBMT groups could significantly increase and decrease the RANKL and OPG, respectively, in the presence of ZA (all p < 0.001). A combination of 660 + 808 nm showed the highest effects on both genes. In conclusion, it seems that PBMT can modulate the effects of ZA by inducing PDLSC proliferation and increasing RANKL-to-OPG gene expression ratio.

Photobiomodulation effects of pulsed and continuous wave near-infrared laser on the proliferation and migration of human gingival fibroblasts: An in vitro study

There are limited data on comparison of pulsed and continuous wave in photobiomodulation therapy (PBM). This study aimed to investigate the effect of PBM with 980 nm laser in pulsed and continuous wave on the proliferation and migration of human gingival fibroblasts (HGF) cells. Cultured HGF were divided into three main groups: (1) irradiated in pulsed mode (frequencies of 50 and 25 KHz; energy densities of 3 and 5 J/cm2 ), (2) irradiated in continuous mode (energy densities of 3.2 and 5.2 J/cm2 ), and (3) no irradiation as control group. HGF proliferation rate was measured by MTT assay at 24, 48, and 72 h post irradiation. In addition, HGF migration rate was measured by scratch test at 24 h post PBM. At 24 h, the group received continuous irradiation at 5.2 J/cm2 showed significantly higher proliferation compared with the control group (p = 0.012). At 48 and 72 h, the groups received continuous, and 50 Hz pulsed irradiation at energy densities of 5.2 and 5 J/cm2 respectively, had significantly higher HGF proliferation rates compared to the control (p < 0.05). Only the continuous irradiations were effective in significant increase of the cell migration. In conclusion, continuous PBM at energy density of 5.2 J/cm2 showed promising effect on HGF proliferation and migration.

An evaluation of photobiomodulation effects on human gingival fibroblast cells under hyperglycemic condition: an in vitro study

An in vitro study was designed to evaluate the effects of photobiomodulation (PBM) with 915-nm diode laser on human gingival fibroblast (HGF) cells under hyperglycemic condition. The HGF cells were cultured in Dulbecco's modified eagle medium (DMEM) medium containing 30 mM glucose concentration for 48 h to mimic the hyperglycemic condition. Subsequently, the cells received three sessions of PBM (915 nm, continuous emission mode, 200 mW, energy density values of 3.2, 6, and 9.2 J/cm2). Twenty-four hours post-irradiation, cell proliferation, expression of interleukin 6 (IL-6), and vascular endothelial growth factor (VEGF) were assessed with MTT and real-time polymerase chain reaction (PCR) tests, respectively. Also, reactive oxygen species (ROS) production was measured using CM-H2DCFDA fluorimetry. No changes were detected in the cell proliferation rate between the high glucose control group and laser-treated cells, while VEGF and IL-6 gene expression levels increased significantly after PBM in the high glucose-treated cells group. ROS level was significantly decreased in the irradiated cells in high-glucose medium compared with the high glucose control group. Our study revealed the inductive role of 915-nm-mediated PBM on VEGF and the inflammatory response while concurrently reducing reactive oxygen species production in HGF cells in hyperglycemic conditions.

Clinical and Histomorphometric Assessment of Lateral Alveolar Ridge Augmentation Using a Corticocancellous Freeze-Dried Allograft Bone Block

Horizontal ridge augmentation with allografts has attracted notable attention because of its proper success rate and the lack of disadvantages of autografts. Corticocancellous block allografts have not been adequately studied in humans. Therefore, this study clinically and histomorphometrically evaluated the increase in ridge width after horizontal ridge augmentation using corticocancellous block allografts as well as implant success after 12 to 18 months after implantation. In 10 patients receiving implants (3 women, 7 men; mean age = 45 years), defective maxillary alveolar ridges were horizontally augmented using freeze-dried bone allograft blocks. Ridge widths were measured before augmentation, immediately after augmentation, and ∼6 months later in the reentry surgery for implantation. This was done at points 2 mm (A) and 5 mm (B) apically to the crest. Biopsy cores were acquired from the implantation site. Implant success was assessed 15.1 ± 2.7 months after implantation (range = 12-18 months). Data were analyzed using Friedman and Dunn tests (α = 0.05). At point A, ridge widths were 2.77 ± 0.37, 8.02 ± 0.87, and 6.40 ± 0.66 mm, respectively, before surgery, immediately after surgery, and before implantation. At point B, ridge widths were 3.40 ± 0.39, 9.35 ± 1.16, and 7.40 ± 1.10 mm, respectively, before surgery, immediately after surgery, and before implantation. The Friedman test showed significant increases in ridge widths, both at point A and point B (both P = .0000). Postaugmentation resorption was about 1.5-2 mm and was statistically significant at points A and B (P < .05, Dunn). The percentage of newly formed bone, residual graft material, and soft tissue were 33.0% ± 11.35% (95% confidence interval [CI] = 24.88%-41.12%), 37.50% ± 19.04% (95% CI = 23.88%-51.12%), and 29.5%, respectively. The inflammation was limited to grades 1 or zero. Twelve to 18 months after implantation, no implants caused pain or showed exudates or pockets. Radiographic bone loss was 2.0 ± 0.7 mm (range = 1-3). It can be concluded that lateral ridge augmentation with corticocancellous allograft blocks might be successful both clinically and histologically. Implants might have a proper clinical success after a minimum of 12 months.

Immediate implantation of pure titanium implants into extraction sockets of Macaca fascicularis. Part II: Histologic observations

The purpose of this study was to evaluate immediate implants with implants placed in ossified extraction (control) sites. Histologic observation of immediate and control implants showed similar levels of bone integration at the light microscopic level using ground-section and decalcified thin-section histologic methods. Both histologic methods provided similar information in relation to determination of hard and soft tissue components measured at the interface. The percentage of bone integration was similar in different anatomic regions of the oral cavity. Bone patterns peripheral to the interface region differed, suggesting that special consideration be given to implants placed in the posterior regions of the maxilla and mandible.

Immediate implantation of pure titanium implants into extraction sockets of Macaca fascicularis. Part I: Clinical and radiographic assessment

Immediate implants have the advantages of few surgical exposures, short treatment time, and maintenance of alveolar bone height and width. The purpose of this study was to compare immediate implants with conventional implants (implants placed into ossified extraction sites) in adult monkeys. Forty-eight implants were placed and allowed to heal for a 6-month period. Following a 7-month loading period, the monkeys were sacrificed, and implant sections were evaluated histologically. Clinical and radiographic measurements showed few significant differences between immediate and control implants.

The growth of postdoctoral general dentistry programs

From 1972 to 1990, the number of Postdoctoral General Dentistry (PGD) programs increased by 57% and enrollment increased by 57% and enrollment increased by 131% for a total of 118 PGD programs and 1,367 positions. Although there has been some increase in military and Veterans Affairs (VA) programs, the major increase was in civilian programs. From 1972-78, the major impetus for growth was hospital sponsorship of General Practice Residency (GPR) programs. With federal funding of PGD programs, civilian GPR programs continued to be the main source of growth until the accreditation of Advanced Education in General Dentistry (AEGD) programs in 1981. Subsequently, almost all increases were in AEGD programs. Over the 12-year period of federal funding (1978-90), there was an increase of 406 civilian PGD positions to make a total of 925 positions. The increase in enrollment directly attributable to federal funding was 242. The "unmet demand" for PGD programs was estimated to be approximately 300 positions for 1990, from data derived from the Survey of Dental Seniors and the Matching Program. Assuming that the number of PGD positions continues to increase by 35 positions a year, as it has in the past 12 years, the unmet demand would be met in slightly less than 10 years. If, however, a postdoctoral year was mandated for licensure, the increase in the number of positions would be far short of projected need.

Prepubertal trauma and mandibular asymmetry in orthognathic surgery and orthodontic patients

The association between radiographic evidence of mandibular asymmetry and history of prepubertal trauma was analyzed in orthognathic surgery patients and orthodontic patients. There were statistically significant associations between radiographic evidence of mandibular asymmetry and a history of prepubertal trauma in both patient groups. The results suggest that prepubertal trauma could be one etiologic factor for the development of mandibular asymmetry.

Practice characteristics of graduates of postdoctoral general dentistry programs

A mail questionnaire was sent to 900 dentists who completed a Postdoctoral General Dentistry (PGD) program in 1985 and 900 dentists who graduated from dental school in 1985 but did not participate in a PGD program. The response rate was 57 percent. Three-quarters of the PGD graduates trained in civilian programs with the remainder being equally divided between military and Veterans Administration (VA) programs. Graduates of military programs continued to be employed by the military five years after graduation in contrast to the VA where less than 2 percent of graduates were employed after five years. The percent of dentists who are specialists or are enrolled in specialty programs five years after graduation was approximately 13 percent and the rates were similar for PGD and non-PGD dentists. The patterns of care in private practice tended to be similar for both groups; however, in institutions GPR graduates provided more treatment for special care patients and patients who were economically disadvantaged. GPR graduates also were more involved in teaching and in hospital activities.

An American Board of Orthodontics case report. Correction of a Class III mandibular prognathism and asymmetry through orthodontics and orthognathic surgery

The Class III malocclusion with mandibular prognathism can involve many factors, among which are excessive mandibular growth, underdevelopment of the maxilla, environmental factors, and trauma to the jaws. The correction of this malocclusion can involve an orthodontic or a combined orthodontic-orthognathic approach. Skeletal asymmetries can complicate this situation, making treatment either more difficult, more complicated, or both. This case presentation involves treatment with a combined orthodontic-orthognathic approach. [This case was presented to the American Board of Orthodontics in partial fulfillment of the requirements for the certification process conducted by the Board.]

Resolving esthetic and phonetic problems associated with maxillary implant-supported prostheses. A clinical report

A technique has been presented for placement of an implant prosthesis without a visually detectable space between the prosthesis and soft tissue or visibility of the metal abutments. The prosthesis permits better phonetics and greatly improved esthetics including better lip support. Proper presurgical planning and careful assessment of the potential level of home care are especially important when this technique is used.

An American Board of Orthodontics case report. A combined face mask-orthognathic surgical approach in the treatment of skeletal open bite and maxillary deficiency

This case report is presented following the specifications of the American Board of Orthodontics. The patient had a true skeletal open bite with maxillary and mandibular asymmetry. She was treated with an orthognathic surgical approach and face mask therapy to stabilize the postsurgical result.

Evaluation of common predictors for selection of postdoctoral dental students

Certain predictors are traditionally presumed to be reliable measures for selection of candidates for general dentistry training programs. The purpose of this study was to assess the relative value of academic standing, letters of recommendation, and personal interview impressions by comparing them with performance during training. Predictor data were collected from the application files of all postdoctoral trainees in the advanced general dentistry training program at the Eastern Dental Center of the past ten years (N = 154). However, only 102 postdoctoral students had information available for all three predictor criteria. Performance was rated subjectively on completion of training by two faculty members on a six-point rating scale. The highest correlations between predictors and performance were to academic achievement (r = 0.347). Weaker, though statistically significant, correlations were found for the personal interview (r = 0.206) and letters of recommendation (r = 0.192). Although these predictor criteria will continue to be used in the selection of candidates, administrators and selection committees must be aware of the limitations of such criteria in predicting performance.

Ambulatory hospital dentistry

The scope of outpatient hospital dentistry is broad and embraces a full range of patient care as well as education and investigative activities. The ambulatory dental service provides an ideal setting for the care of medically compromised patients and treatment requiring a multidisciplinary approach. The hospital dental staff and administration are especially well qualified to bring dignified, high quality, total health care to patients and educational programs to the profession. These factors are paramount in formulating a strategy for meeting the future health care needs of our population.