Extracellular environment as one mediator of blue light-induced mitochondrial suppression.

OBJECTIVES: The current study tested the hypothesis that the extracellular environment mediates mitochondrial suppression of oral epithelial cells and fibroblasts by blue light. METHODS: We exposed Balb fibroblasts (Balb), normal human epidermal keratinocytes (NHEK), and oral squamous carcinoma cells (OSC2) to blue light (30-120J/cm2) in different cell-culture media and in phosphate buffered saline (PBS). Mitochondrial activity (MTT method) was used to assess cellular response 72 h post-light exposure. Cell-culture media were replaced or supplemented before or after light exposure to assess the variables of exposure time and medium degradation as mediators of blue light-induced effects. RESULTS: Mitochondrial activity of NHEK was not suppressed by exposure to blue light regardless of extracellular conditions. The mitochondrial activity of OSC2 and Balb cells was suppressed most when cells were exposed to light in cell-culture medium (versus PBS). Blue light suppressed mitochondrial activity more when irradiated medium remained in contact with the cells at least 1h, indicating a time-dependence of the medium effects. Neither a replacement nor a supplementation of medium components reduced blue light-induced mitochondrial suppression. SIGNIFICANCE: Our results suggest that tissue environments influence cellular responses to blue light and that these environments should be considered when assessing any biological effects of blue light during the photopolymerization of restorative resins.

Collagen-Coated Bovine Bone in Peri-implantitis Defects: A Pilot Study on a Novel Approach.

PURPOSE: As dental implants have become routine therapy, clinicians are more frequently being faced with treating peri-implantitis. To date, no single treatment protocol has been shown to be the preferred means to treat peri-implantitis. The aim of this retrospective case series is to present a novel approach utilizing porcine collagen-coated bovine bone (CBB) to treat peri-implantitis. MATERIALS AND METHODS: Eleven patients, with no history of periodontitis, presenting with peri-implantitis around a single restored dental implant, were included in the study. At initial and follow-up examinations, bleeding on probing (BOP), probing depth (PD), and gingival margin location (GM) were recorded. Following surgical debridement of the peri-implant defect and treatment of the implant surface with a 0.12% chlorhexidine gluconate solution, bony defects were grafted with CBB. All patients had 12 months of follow-up. RESULTS: Upon presentation, average PD at the deepest site (DS) was 7.6 ± 1.9 mm. At the time of surgery, excess cement was found around nine implants (81%). All patients healed uneventfully without postoperative complications. At 6 and 12 months, all implants showed favorable results with average DS PD reduction of 3.9 ± 1.5 mm and 4.1 ± 1.6 mm, respectively. All implants showed radiographic signs of bone fill, while GM showed no changes from preoperative measurements at either 6 (0.1 ± 0.5 mm) or 12 (0.0 ± 0.6 mm) months. CONCLUSION: The use of a porcine collagen-coated bovine bone graft to treat peri-implantitis represents a potentially predictable therapeutic modality. Randomized controlled trials are necessary to substantiate the treatment outcomes.

Dimensional changes during early healing after a subepithelial connective tissue graft procedure.

BACKGROUND: The subepithelial connective tissue graft (CTG) is a popular means to treat gingival recession and augment keratinized tissue. Studies exist that examine long-term outcomes of this procedure; however, changes in tissue dimensions during early healing (0 to 21 days postoperatively) are unknown. The aim of this study is to examine bucco-lingual tissue dimension (gingival tissue thickness [GT]) changes during early CTG healing using a non-invasive technique. METHODS: Thirteen patients who had treatment planned for CTG on a single tooth were recruited for the study. Using a customized acrylic stent, GT was measured preoperatively, at surgery completion, and at 3, 7, 14, and 21 days postoperatively. CTG was performed using an envelope technique. GT changes were analyzed by repeated-measures analysis of variance. RESULTS: All CTG procedures were considered successful with no postoperative complications. GT increased 1.5 mm immediately after surgery (baseline) compared to the preoperative measurement. GT increased on average 96%, 47%, and 2% compared to baseline at days 3, 7, and 14, respectively. Day 3 and day 7 measurements were significantly different from baseline (P <0.001). At day 21, GT decreased 15% compared to baseline, with an average increase of 1.29 mm from preoperative measurements. CONCLUSIONS: The early postoperative healing of CTGs used for root coverage exhibits a significant but transient increase in bucco-lingual tissue dimension. The observed increase in bucco-lingual tissue dimension subsides by the end of the second postoperative week.

Blue light activates phase 2 response proteins and slows growth of a431 epidermoid carcinoma xenografts.

BACKGROUND: Recent studies suggest that light in the UVA range (320-400 nm) activates signaling pathways that are anti-inflammatory, antioxidative and play a critical role in protection against cancer. These effects have been attributed to NF-E2-related factor (NRF2)-mediated up-regulation of 'phase 2' genes that neutralize oxidative stress and metabolize electrophiles. We had previously shown that small doses of blue light (400-500 nm) had selective toxicity for cultured oral tumor cells and increased levels of peroxiredoxin phase 2 proteins, which led to our hypothesis that blue light activates NRF2 signaling. MATERIALS AND METHODS: A431 epidermoid carcinoma cells were treated in culture and as nude mouse xenografts with doses of blue light. Cell lysates and tumor samples were tested for NRF2 activation, and for markers of proliferation and oxidative stress. RESULTS: Blue light activated the phase 2 response in cultured A431 cells and reduced their viability dose dependently. Light treatment of tumors reduced tumor growth, and levels of proliferating cell nuclear antigen (PCNA), and oxidized proteins. DISCUSSION: Cellular responses to these light energies are worth further study and may provide therapeutic interventions for inflammation and cancer.

Recombinant human bone morphogenetic protein-2 for peri-implant bone regeneration: a case report.

BACKGROUND: Currently, clinicians have a limited treatment arsenal in the repair of peri-implant defects. The aim of the present report is to present the clinical results of treating a dental implant using recombinant human bone morphogenetic protein (rhBMP)-2 in an elderly patient. METHODS: A 75-year-old man presented for routine dental prophylaxis. Clinical and radiographic examination revealed significant loss of attachment and bone loss around an implant replacing the maxillary left first molar. The patient did not report any symptoms, and the implant showed no signs of mobility. Because of the severity of the defect, regenerative treatment using a combination of rhBMP-2 and freeze-dried bone allograft was used. RESULTS: The patient was followed for 80 weeks postoperatively. By 28 weeks, significant probing depth reduction and radiographic bone fill was observed, and the original implant crown was replaced. From 28 weeks postoperatively to 80 weeks, no significant clinical or radiographic changes were observed. CONCLUSIONS: rhBMP-2 represents a potential therapeutic modality for severe peri-implant hard tissue loss. Future studies should examine parameters, such as surgical technique, to maximize the rhBMP-2-driven regenerative outcomes.