The role of gingival connective tissue in determining epithelial differentiation

Free grafts of connective tissue, without epithelium, were transplanted from either the keratinized gingiva or the nonkeratinized alveolar mucosa (controls) into areas of the alveolar mucosa in 7 monkeys. The grafts were placed in pouches created in the connective tissue as close as possible to the overlying epithelium. After 3-4 wk, the transplants were exposed by removal of the overlying tissue in order to allow epithelialization from the surrounding nonkeratinized alveolar mucosa. The transplants were examined clinically and histologically at time periods between 1 and 12 mth. The gingival connective tissue grafts became covered with keratinized epithelium displaying the same characteristics as those of normal gingival epithelium. The alveolar mucosa transplants were covered with nonkeratinized epithelium. This indicates that gingival connective tissue is capable of inducing the formation of a keratinized gingival epithelium.link_to_subscribed_fulltex

The effect of a deproteinized bovine bone mineral on bone regeneration around titanium dental implants

The aim of the present experiment was to test the effect of a deproteinized bovine bone mineral (Bio-Oss®) on guided bone regeneration (GBR) in dehiscence defects around implants. The first 2 molars and all premolars were extracted on both sides of the mandibles of 3 monkeys (Macaca fascicularis). Three months later, 2 titanium plasma-coated cylindrical implants were placed in all quadrants of each monkey. During the surgical procedure, standardized dehiscence defects were produced buccally and lingually, mea suring 2.5 mm in width and 3 mm in height. Four different experimental situations were created: 2 sites in each monkey were covered with an ePTFE membrane (M), 2 were filled with the graft material (DBBM), 2 were filled with the graft material and also covered with a membrane (M+DBBM), and 2 control sites were neither grafted nor covered (C). The flaps were sutured to allow for primary healing. Linear measurements of bone height and width were calculated on histological specimens obtained 6 months following surgery. In addition, values for bone density and for surface fraction of graft to new bone contact were measured. Vertical bone growth along the implant surface of 100% (SD 0%) for M+DBBM, 91% (SD 9%) for M, 52% (SD 24%) for DBBM, and 42% (SD 35%) for C was measured. The width of the regenerated bone 1.5 mm above the bottom of the original defect, i.e. at the 50% mark of the vertical extension of the defect, in relation to the width at the bottom of the defect amounted to 97% (SD 2%) for M+DBBM, 85% (SD 9%) for M, 42% (SD 41%) for DBBM, and 23% (SD 31%) for C. Assessment of bone density within the confinement of the regenerated bone resulted in an increase of 30% (SD 11%) for M+DBBM, 45% (SD 20%) for M, 33% (SD 20%) for DBBM, and 22% (SD 23%) for C. The values for graft to new bone contact within this compartment amounted to 80% (SD 15%) for M+DBBM and 89% (SD 14%) for DBBM. In conclusion, BioOss® exhibited osteoconductive properties and hence can be recommended for GBR procedures in dehiscence defects with respect to vertical and horizontal growth of bone. © Munksgaard 1998.link_to_subscribed_fulltex

Plaque-induced peri-implantitis in the presence or absence of keratinized mucosa. An experimental study in monkeys.

In 5 monkeys a total of 30 transmucosal endosseous dental implants were inserted in edentulous areas of the mandible with presence or absence of keratinized mucosa. After a healing period of 3 months with optimal plaque control, all implants were exposed to plaque accumulation for periods up to 9 months. To secure abundant plaque accumulation on half the number of the implants, cotton wool ligatures were placed around the implants at the entrance to the peri-implant sulcus. Attachment loss was measured clinically and histometrically, and tissue recession was measured clinically. Ligated implants without keratinized mucosa demonstrated significantly more recession and slightly more attachment loss than the other implants. The results of this study suggest that the absence of keratinized mucosa around dental endosseous implants increases the susceptibility of the peri-implant region to plaque-induced tissue destruction.link_to_subscribed_fulltex

Sture Rickard Nymann 1922-2002.

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Fifth European Workshop on Periodontology (EWP) of the European Academy of Periodontology (EAP), Charterhouse at Ittingen, Thurgau, Switzerland

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