Improvement of apical papilla cell attachment after erbium, chromium-doped yttrium, scandium, gallium, and garnet laser application: a study in an ex vivo immature tooth model.

The purposes of this study were (1) to investigate the direct effect of an Er,Cr:YSGG laser on human apical papilla cell (APC) proliferation and mineralization and (2) to examine the effect of Er,Cr:YSGG laser, when applied to an ex vivo immature tooth model, on APC attachment. An Er,Cr:YSGG laser at various power outputs (0.1, 0.5, and 1 W) was used at different positions (2, 5, or 8 mm from the cells) to irradiate cultured APCs. APC proliferation and mineralization were assessed at various intervals. For the cell attachment evaluation, ex vivo tooth models containing dentin samples were irrigated with either EDTA or normal saline solution (NSS) and supplemented with laser activation. Fibronectin-positive-staining cells were counted and analyzed. The number of APCs was significantly greater when power outputs of 0.1 W and 0.5 W were used than when 1 W was used (P < 0.05). The close contact of laser application, at 2 and 5 mm, exerted a negative effect on cell proliferation at 24 and 48 h. The application at 8 mm did not show the deterioration effect. APC mineralization was reduced after laser irradiation, regardless of the power and the tip positioning, at 21 days. APC attachment in all laser-activated groups was significantly greater than in the groups without laser. The use of Er,Cr:YSGG laser significantly promoted APC attachment on the root canal dentin.

Dynamic Irrigation Promotes Apical Papilla Cell Attachment in an Ex Vivo Immature Root Canal Model.

INTRODUCTION: The use of dentin preconditioning techniques in regenerative endodontic procedures is currently promising. Several growth factors have been detected on dentin after ultrasonic irrigation with EDTA. This study aimed to evaluate the effects of dynamic irrigation with different solution regimens on apical papilla cell (APC) attachment in an ex vivo immature tooth model. METHODS: Various dynamic irrigation techniques, needle irrigation (NI), NI with EndoActivator, and NI with passive ultrasonic irrigation, were used with different solution regimens, normal saline solution (NSS), EDTA, and chlorhexidine digluconate followed by EDTA, in enlarged root canal models where calcium hydroxide-medicated dentin slices were inserted. The initial number of attached fibronectin-positive APCs was counted. Dentin surface morphology was also inspected by using scanning electron microscopy. RESULTS: The number of APCs was significantly greater in the dynamic irrigation groups than in the control group (P < .001). Greater APC numbers were observed in the groups in which NSS was used than in those in which EDTA or chlorhexidine digluconate/EDTA was used, when using the same techniques (P < .001). Cell numbers were similar at all levels of the root canals; however, in the ultrasonically supplemented group irrigated with NSS, the number of attached cells was significantly increased at the middle and apical levels (P < .05). CONCLUSIONS: The use of dynamic irrigation techniques in an immature tooth model definitely promoted APC attachment to calcium hydroxide-medicated dentin. Furthermore, when NSS was used as a final irrigant, the number of attached cells was significantly increased.

Regenerative capacity of human dental pulp and apical papilla cells after treatment with a 3-antibiotic mixture.

INTRODUCTION: A 3-antibiotic combination (3Mix) has been widely used in regenerative endodontics. Recent studies recommend that a safe concentration of 3Mix is in the range of 0.39 µg/mL and 1 mg/mL because higher concentrations may limit tissue regeneration. The aim of this study was to determine the regenerative capacity of isolated human dental pulp cells (DPCs) and apical papilla cells (APCs) after a 7-day treatment with selected doses of 3Mix. METHODS: Primary human DPCs/APCs from the third passage were divided into control and experimental groups. In the control group, cells were cultured in regular complete media. In the experimental group, cells were cultured in complete media containing 0.39 µg/mL or 1 mg/mL of 3Mix for 7 days. After the treatment period, the media were changed, and the cells were further tested for proliferation and differentiation potential. For cell proliferation, a colorimetric qualification of 3-[4, 5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide was used on days 1, 3, 5, and 7. For differentiation potential, a dentinogenic differentiation medium was added into treated cells and cultured for 7, 14, and 21 days. Results were analyzed using quantitative alizarin red S staining and real-time reverse-transcription polymerase chain reaction. RESULTS: After 7 days of treatment, 100% cell death was discovered in the 1-mg/mL 3Mix group. The proliferative capacity of 0.39 µg/mL 3Mix-treated DPCs and APCs was significantly lower than that of untreated cells at all time points (P < .05). Mineralized nodule formation was found both in the 3Mix-treated and control groups, but it was significantly less in the 3Mix-treated groups at 7, 14, and 21 days (P < .01). Quantitative reverse-transcription polymerase chain reaction showed no statistically significant difference (95% confidence interval) in bone sialoprotein, alkaline phosphatase, and dentin matrix protein 1 gene expression in either 3Mix-treated DPCs or APCs compared with control groups. CONCLUSIONS: One milligram per milliliter of 3Mix had strong toxicity to DPCs/APCs when applied for 7 days, whereas 0.39 µg/mL 3Mix showed no toxicity but still affected cell proliferation and mineralization potential. However, no differences in dentinogenic gene expressions were observed between the 3Mix-treated and untreated groups.