Osteogenic and adipogenic induction potential of human periodontal cells.

BACKGROUND: Human periodontium contains different cell types that have various potential roles in hard and soft tissue regeneration. However, there is limited knowledge about how these diverse cell populations contribute to the regenerative process. In this study, we investigated the surface marker difference between different periodontal cells (alveolar osteoblasts [AOs], periodontal ligament fibroblasts [PDLFs], and gingival fibroblasts [GFs]) and their differentiation potential toward osteogenic and adipogenic phenotypes. METHODS: Periodontal cells (AOs, PDLFs, and GFs) from 14 subjects were isolated. The surface antigen expression pattern of cells was analyzed by cell flow cytometry, and the molecular and histologic characterizations under osteogenic and adipogenic inductions were monitored by reverse transcription-polymerase chain reaction, Western blot, and immunocytohistology. RESULTS: The cell phenotypes of AOs were verified by the high expressions of CD29 and CD49a, whereas PDLFs showed distinctively low levels of CD63 and CD73. Under adipogenic induction, limited AOs formed cube-shaped adipose-like cells, whereas PDLFs formed spindle-shaped adipose-like cells. All three cell types expressed baseline osteo-related genes. AOs demonstrated the highest osteogenic ability followed by PDLFs and GFs. CONCLUSIONS: Cells in alveolar bone and periodontal ligament contain osteogenic and adipogenic progenitors. These observations indicate a possible application for periodontium cells in hard or soft tissue regeneration.

Tissue engineering of a periodontal ligament-alveolar bone graft construct.

PURPOSE: This paper reports on a 2-phase study of a novel membrane-scaffold graft construct, its ability to support periodontal ligament fibroblast (PDLF) and alveolar osteoblast (AO) growth in vitro, and its use for tissue engineering a PDL-AO interface in vivo. MATERIALS AND METHODS: Human PDLFs were seeded onto perforated poly(epsilon-caprolactone) membranes (n=30) at 78,000 cells/cm2; human AOs were seeded on poly(epsilon-caprolactone) scaffolds (n=30) with fibrin glue at 625,000 cells/cm3. Cell attachment, morphology, viability, and metabolic activity were monitored for 3 weeks in vitro. Subsequently, cell-seeded membrane-scaffold constructs (experimental group, n=9) and nonseeded constructs (control group, n=4) assembled with fibrin glue were implanted subcutaneously into 7 athymic mice for 4 weeks. RESULTS: PDLFs formed confluent layers on membranes, whereas AOs produced mineralized matrices within scaffolds upon osteoinduction in vitro. Well-vascularized tissue formation was observed after implantation. Integration at the membrane-scaffold interface was enhanced in the experimental group. Type I collagen, type III collagen, fibronectin, and vitronectin were found adjacent to membranes and within constructs. Bone sialoprotein expression and bone formation were undetectable. DISCUSSION: Membrane perforation and scaffold porosity facilitated tissue integration and vascularization at the construct-recipient site. However, the interaction between PDLF and AO could have interfered with osteogenesis at the interface of soft and mineralizing tissues. CONCLUSIONS: Both matrices supported PDLF and AO attachment and proliferation in vitro. The membrane-scaffold construct facilitated tissue growth and vascularization while providing strength and form in vivo.

The effect of basic fibroblast growth factor on delayed-replanted monkey teeth.

BACKGROUND: Basic fibroblast growth factor (bFGF; FGF-2) has been reported to facilitate wound healing and periodontal regeneration in experimental alveolar bone defects. The purpose of this study was to evaluate histologically the effect of topically applied bFGF with or without fibrin glue on delayed-replanted monkey teeth prone to replacement resorption. METHODS: Forty-five roots from five monkeys were endodontically treated aseptically and then extracted as atraumatically as possible. Ten negative control roots were replanted immediately, while 12 positive control roots were allowed to bench dry for 1 hour prior to replantation, both without further treatment. Roots in the two experimental groups were bench dried for 1 hour, rinsed with saline, and then replanted into sockets filled with bFGF with (11 roots) or without (12 roots) fibrin glue. After 12 weeks, histological sections were prepared and evaluated according to morphometric analysis as complete healing or unfavorable healing composed of inflammatory resorption and replacement resorption. RESULTS: Kruskal-Wallis and Mann-Whitney U tests showed teeth in the negative control group to have significantly higher complete healing (98.88% +/- 2.30%) and significantly lower unfavorable healing (1.12% +/- 2.30%) than the positive control group and the experimental groups. bFGF/fibrin glue group showed higher occurrence of complete healing (39.06% +/- 41.62%) compared to the bFGF group (25.28% +/- 28.85%) and the positive control group (16.58% +/- 19.60%), although the differences were not significant. Comparing the complete and unfavorable healing, there was no significant difference in the bFGF/fibrin glue group (P = 0.47), but the differences were significant in the other groups (P < 0.05). CONCLUSION: Topical application of bFGF with fibrin glue showed an insignificantly higher occurrence of complete healing in delayed-replanted monkey teeth.

pH changes in root dentin after intracanal placement of improved calcium hydroxide containing gutta-percha points.

The in vitro pH changes in root dentin over a period of 2 weeks was investigated in 48 extracted bicuspids after intracanal placement of either Roeko Calcium Hydroxide Plus Points, aqueous calcium hydroxide paste, or gutta-percha points (control group) after root canal preparation. Microelectrodes were placed in outer and inner root dentin at cervical, middle, and apical thirds of the root to measure the pH at 1 h, 2 h, 3 h, 1 day, 3 days, 7 days, and 14 days. Roeko Calcium Hydroxide Plus Points reached a peak inner dentine pH of 11.67 and a peak outer dentine pH of 10.82 at 3 h. In addition, Roeko Calcium Hydroxide Plus Points maintained an outer dentine pH above 9.5 for approximately 2 days, whereas the aqueous calcium hydroxide paste did not reach this pH. However, the alkalinity in dentin with Roeko Calcium Hydroxide Plus Points was maintained for 7 days only, whereas aqueous calcium hydroxide paste maintained an alkaline environment throughout the 2-week period.

The effect of Emdogain gel on periodontal healing in replanted monkeys' teeth.

OBJECTIVE: We sought to histologically evaluate the effect of Emdogain gel on periodontal healing in monkeys' teeth undergoing delayed replantation. Study design Mature monkey teeth simulating avulsion were endodontically treated before extraction. Negative control teeth (group N = 10 roots) underwent immediate replantation, whereas the rest were bench-dried for 1 hour and treated in one of the following ways before replantation: the positive control teeth (group P = 12 roots) had no further treatment; group C teeth (4 roots) had the periodontal ligament removed; group D teeth (10 roots) were treated with Emdogain gel; group E teeth (6 roots) had the periodontal ligament removed before the application of Emdogain gel; and group F teeth (7 roots) had the periodontal ligament removed, the root surface conditioned, and Emdogain gel applied. Periodontal healing was evaluated after 16 weeks by undertaking histomorphometric analysis. RESULTS: The Kruskal-Wallis and Mann-Whitney U tests revealed that group N teeth had a statistically higher occurrence of complete healing than did all other groups, whereas group P was not significantly different in any of the healing categories from D, E, and F, the groups in which Emdogain gel was used. Group C teeth had a significantly higher occurrence of replacement root resorption than did the teeth in groups P and F-but were not significantly different from teeth in groups D and E. CONCLUSION: Emdogain gel did not appear to significantly reduce replacement resorption in monkeys' teeth that had undergone delayed replantation.

Comparison of acidic fibroblast growth factor on collagen carrier with calcium hydroxide as pulp capping agents in monkeys.

Acidic fibroblast growth factor (aFGF) has been shown to facilitate wound healing by stimulating fibroblast proliferation and angiogenesis. It has also been reported to possess a powerful anti-apoptotic function This study compared the histological pulp responses to aFGF on collagen carrier and Ca(OH)(2) placed on the mechanically exposed dental pulp in monkeys at two observation periods. Thirty-six teeth with pulp exposures were distributed into three groups according to the capping agents used prior to application of the coronal seal: collagen-based matrix carrier (group 1), aFGF on the collagen-based matrix carrier (group 2) and aqueous calcium hydroxide [Ca(OH)(2)] paste (group 3). Specimens were harvested at 6 and 13 weeks postoperatively and prepared for hematoxylin and eosin, and Gram staining. Histological qualitative evaluation of pulp responses were performed under the light microscope following criteria modified from Cox et al. (17) and Hu et al. (18). Semi-quantitative analysis was also carried out using Kruskal-Wallis and Mann-Whitney U-tests. There was neither negligible inflammatory infiltrates with no bacteria present in the three groups at both timings, nor was there any significant difference in the soft tissue organization among the three groups at or between the 6- and 13-week observation periods. At 6 weeks, the hard tissue barrier produced by Ca(OH)(2) group (1.040 +/- 0.089) was significantly more superior than aFGF/collagen carrier group (1.930 +/- 0.825) (P = 0.030) as well as collagen carrier group (3.142 +/- 1.069, P = 0.018). At 13 weeks, both aFGF/collagen carrier group (1.214 +/- 0.485) and the collagen carrier group (1.457 +/- 0.814) produced significantly better hard tissue barrier (P = 0.040 and P = 0.017, respectively) than earlier timing. However, these two groups did not induce significantly improved hard tissue barrier compared to that produced by aqueous Ca(OH)(2) paste which stimulated matrix secretion in a polar tubular dentin-like pattern.

Dental therapists' experience in the immediate management of traumatized teeth.

The optimal immediate management of traumatized teeth is known to be important for long-term success. One hundred and sixty-seven school dental therapists with General Certificate of Education 'Ordinary' (GCE 'O') level qualification were surveyed on their knowledge and experience on immediate management of dental trauma. The results showed only 41.2% felt comfortable with their present knowledge on the subject. A high proportion of the respondents (94.6%) indicated a need for more knowledge. All therapists concurred on the need to replant a permanent tooth and most (85.1%) agreed that this should be done within 30 min. More than half (54.8%) were not sure of the optimal storage medium for avulsed teeth. Their attitude towards acquiring knowledge in this aspect was good (80.5%) and all would take immediate action to settle appointments for trauma cases.

The effect of topical minocycline on replacement resorption of replanted monkeys' teeth.

Tetracycline has been reported to possess antiresorptive properties in addition to antimicrobial actions. Systemic administration of tetracycline showed variable results in the control of replacement resorption after replantation with good results in half of the cases, and almost no healing in the rest. The purpose of this study was to evaluate histologically the effect of topically applied minocycline on replacement resorption of replanted monkeys' teeth. Thirty-two roots from seven monkeys were endodontically treated aseptically to prevent inflammatory resorption of pulpal origin, a common sequela after avulsion injury. Teeth were then extracted as atraumatically as possible. Teeth in the negative control group (10 roots) were replanted almost immediately, while teeth in the positive control group (12 roots) were allowed to bench-dry for 1 h prior to replantation, both without further treatment. Teeth in the experimental group (10 roots) were bench-dried for 1 h, rinsed with saline, and then immersed in 1 ml of 50 mg ml(-1) minocycline hydrochloride for 5 min before replantation. No splinting was used. After 12 weeks, the animals were sacrificed and histological sections were prepared and evaluated according to a morphometric analysis modified from that described by Andreasen (1987) as complete healing, inflammatory resorption, and replacement resorption. Kruskal-Wallis test showed significant differences among the three groups in all the three healing categories. Further analysis with Mann-Whitney U-test showed teeth in the negative control group to have significantly higher complete healing and significant lower unfavorable healing, comprising of replacement resorption and inflammatory root resorption than the positive control group and the minocycline group. Topical application of minocycline to the root surface appeared to result in slightly higher occurrence of complete healing (32.46%) compared to the delayed replantation group with no minocycline treatment (positive control) (16.58%), but the difference was not statistically significant (P = 0.09).

The effect of intracanal Ledermix on root resorption of delayed-replanted monkey teeth.

Progressive root resorption is one of the common sequelae in replanted teeth, which is detrimental to their long-term prognosis. Ledermix paste, with its composition of triamcinolone acetonide and demethylclortetracycline, has been shown to inhibit inflammation and the associated hard tissue resorption. This study evaluated the effect of immediate intracanal Ledermix on root resorption of delayed-replanted monkey teeth. A total of 36 roots were root canal treated. For the experimental group, intracanal Ledermix was placed prior to extraction and replantation after 1-h bench dry. The positive control group was root filled and replanted after 1 h while the negative control group was root filled and replanted immediately. The monkeys were sacrificed after 12 weeks. The H&E histological tissue specimens were prepared and evaluated using a method modified from that of Andreasen's morphometric analysis, as favorable or complete healing and unfavorable healing, comprising inflammatory root resorption and replacement resorption. The results were analyzed using Kruskal-Wallis and Mann-Whitney U-tests as well as Wilcoxon signed ranks test. The negative control group produced highly significant favorable healing and unfavorable healing as compared to the Ledermix group (P = 0.000). The Ledermix group only showed significantly higher occurrence of complete healing (35.46%) compared to the positive control group (16.58%) (P = 0.037) but there were no significant differences in the inflammatory root resorption and replacement resorption. Nevertheless, when the latter two unfavorable healing patterns were combined, there was a significantly lower overall unfavorable healing in the Ledermix group (64.54%) when compared to the positive control group (83.43%) (P = 0.037). This unfavorable healing outcome in the Ledermix group, however, was not significantly different from the favorable healing outcome with the same treatment modality (P = 0.110).