Lein-Tuan Hou

Preparation of porous scaffolds by using freeze-extraction and freeze-gelation methods.

Freeze-fixation and freeze-gelation methods are presented in this paper which can be used to prepare highly porous scaffolds without using the time and energy consuming freeze-drying process. The porous structure was generated during the freeze of a polymer solution, following which either the solvent was extracted by a non-solvent or the polymer was gelled under the freezing condition; thus, the porous structure would not be destructed during the subsequent drying stage. Compared with the freeze-drying method, the presented methods are time and energy-saving, with less residual solvent, and easier to be scaled up. Besides, the problem of formation of surface skin can be resolved and the limitation of using solvent with low boiling point can be lifted by the presented methods. With the freeze-extraction and freeze-gelation methods, porous PLLA, PLGA, chitosan and alginate scaffolds were successfully fabricated. In addition to the presentation of the morphologies of the fabricated scaffolds, preliminary data of cell culture on them are as well included in the present work.

Autologous transplantation of gingival fibroblast-like cells and a hydroxylapatite complex graft in the treatment of periodontal osseous defects: cell cultivation and long-term report of cases.

Autogenous cell transplantation via hydroxylapatite (HA) vehicle has been reported to have beneficial effects on the treatment of human periodontal osseous defects. The aim of this study was to explore the possibility of using gingival fibroblast-like cells in the therapy of osseous defects caused by inflammatory periodontitis by reporting long-term results of gingival fibroblast-coated hydroxylapatite (GF–HA) grafting for healing these defects. Gingival fibroblasts were cultured from healthy gingivae of treated subjects. Growth of cells on HA particles was established in vitro, and then the GF–HA complex was transplanted into the periodontal osseous defects. Clinical parameters of gingival and plaque indices, probing depth, and periapical x-ray were monitored at baseline and at various periods from 50 months to 6 years after surgery. Grafting with only HA in the osseous defects of the same patient was used for comparison. The present study shows that GF–HA-treated sites could achieve marked pocket reduction and probing attachment gain at reentry and later recalls. Good clinical bone filling of osseous defects in GF–HA-treated sites was also demonstrated in periapical radiographs (increased bone height and reappearance of the crestal cortex) and in some reentry sites. One HA-treated site was filled with connective tissue only, and the absence of new bone formation was noted during a reentry operation. Another HA-treated site exhibited a comparable increase in radiographic density, while part of HA particles were gradually lost in longer recalls. These limited observations conclude that GF–HA grafting may provide a treatment modality leading to regeneration of periodontal tissues in periodontitis-affected osseous defects. Further studies including more cases and demonstration of the deposition of differentiated periodontal tissues are necessary before further application of this therapy.

Bacterial morphotypes and early cellular responses in clinically infected and non-infected sites after combination therapy of guided tissue regeneration and allograft

OBJECTIVES To compare the bacterial morphotypes and early cellular responses in periodontally treated sites with and without pus formation after a combination of guided tissue regeneration (GTR) and allograft therapy. METHODS 45 subjects with 80 sites having periodontal lesions with moderate to deep pockets and angular bone defects participated. 28 treated sites in 25 patients were included in the studies. 14 sites suffered from symptoms and signs of infection with pus formation during the healing period were assigned to the pus (P) group. Another 14 sites had asymptomatic healing and were assigned to the non-pus (NP) group. The GTR membranes were retrieved 4-6 weeks after surgery and processed for SEM examination. The bacterial morphotypes on the membranes were observed and photographed. Bacterial adhesion score (BAS, 0-5) and the presence of leukocytes and fibroblasts were estimated from photographs. RESULTS The results showed that large numbers of bacteria (high BAS) were present on both sides of the coronal 2/3 of the membrane in both groups, irrespective of clinical conditions. At the apical 1/3 of the membrane, moderate numbers of bacteria were still found on the outer side in the P group. The BAS of rod-shaped bacteria were significantly higher in the P group than that of the NP group on the outer coronal 2/3 of the membrane. The frequency of the presence of fibroblasts (18.5%) at the apical 1/3 of the inner (tooth facing) side of the P group was much lower than that of the same location (28.6-29.6%) in the NP group. The presence of leukocytes and fewer numbers of fibroblasts on the GTR membrane were associated with greater BAS for rod- and filament-shaped bacteria. CONCLUSIONS GTR membranes are commonly colonized by oral bacteria during retention, even on uncomplicated and tissue covered portions. The overt infection clinically (pus group) of the membrane-allograft treated sites is associated with a significantly elevated BAS of rod-shaped bacteria, and may be closely related to the occurrence of its adverse early healing responses (inflammation, pus formation, fewer fibroblasts and greater accumulation of leukocytes).

Double Laterally-Rotated Bilayer Flap Operation for Treatment of Gingival Recession

BACKGROUND AND PURPOSE Many root coverage techniques, such as lateral pedicle flap, double papilla flap, free gingival graft, connective tissue graft, and guided tissue regeneration (GTR) procedure have been widely applied in clinical dental practice. Although they all provide various degrees of successful root coverage, some procedures are technique-sensitive and others require a 2-stage operation. METHODS In this study, we describe a new technique with a double laterally-rotated bilayer flap for root coverage. Briefly, 2 partial-thickness flaps were prepared, one on each side of the gingival recession, and then laterally repositioned (with mutual overlapping) to cover the root exposure. After thorough planing of the exposed root surfaces, root conditioning with saturated citric acid solution (pH = 1.0) was performed. One partial-thickness flap was de-epithelialized and then rotated to cover the citric acid-conditioned root surface. Another partial-thickness flap was further rotated to cover the de-epithelialized flap. Both flaps were sutured to the recipient periosteal bed. This new root coverage technique was used to treat 2 teeth with gingival recession. RESULTS The results demonstrated that this new technique provides satisfactory root coverage of gingival recession and improves root dentin hypersensitivity of treated teeth. The main advantages of this technique are simple 1-stage surgery, esthetic color matching of the soft tissue, and a good blood supply of the reflected flap. CONCLUSIONS We conclude that the double laterally-rotated bilayer flap operation may provide a new alternative for the treatment of gingival recession.