Attachment formation following replantation of cultured cells into periodontal defects--a study in minipigs.

Regeneration processes in the periodontium occur by the interaction of different cell populations. It is known that these cells are also capable of forming new periodontal tissue after culture in vitro. The present study investigated whether replanted cultured cells from the periodontium could contribute to attachment formation. Primary cell cultures from alveolar bone and periodontal ligament were obtained from 11 minipigs. Experimentally induced furaction and interdental defects (n = 168) were treated in groups: (a) flap surgery, replantation of alveolar bone cells, and covering of the defects with Teflon membranes (ABC group); (b) flap surgery, replantation of periodontal ligament cells and membranes (PLC group); (c) flap surgery, bone gelatin (carrier material) and membranes (BG group); (d) flap surgery and membranes (NBG group); (e) flap surgery (FS group); and (f) no treatment (NT group). The defects were clinically and histologically (polyfluorochrome labeling) assessed after 10, 30, and 90 days. In the ABC group, initial calcified tissue formation at the roots was apparent after only 8 days. Marked new formation of cementum and alveolar bone and the development of a new attachment were observed after 90 days. In the BG and the NBG groups, wound healing varied depending on membrane healing and the morphology of the defects, which led to significantly poorer and variable results. Similar results were found in the PLC group, although some defects showed extensive cementum and bone formation. Defects in the FS and the NT groups healed largely by epithelialization. The study shows that replantation of cultured alveolar bone cells leads to formation of new cementum and bone, which, in turn, leads to formation of a new attachment. It is likely that the cells stabilize the tissue formation in the defect or on the root surface in the early phase of wound healing and prevent epithelial downgrowth. Results also show that regeneration in the periodontium is determined by the availability of (precursor) cells capable of forming calcified tissues.

Formation of differentiated tissues in vivo by periodontal cell populations cultured in vitro.

The periodontium contains heterogeneous mesenchymal cell populations with various differentiation potentials. The capacity of these cells for tissue formation as well as the origin of their precursors are still not entirely defined. In this study, cells originating from different periodontal tissues were cultured in vitro, and tissue formation in vivo following orthotopic re-implantation was investigated. Cells were recovered from the alveolar bone and periodontal ligament tissue of six minipigs, and cultured cells were then grown on extracted dental roots from the homologous animals by means of co-culture in vitro. Each minipig received 2 roots covered with alveolar bone cells, 2 roots covered with periodontal ligament cells, and 2 control roots (without cells) implanted into palatal bone defects. Intravital fluorochrome labeling was performed, and two minipigs were histologically examined after 2, 4, and 12 weeks in each case. Controls showed widespread resorption and ankylosis, whereas roots covered with cultured periodontal cells exhibited tissue formation in vivo. Alveolar bone cells synthesized a calcified cellular tissue resembling cellular cementum, suggesting that cells within this population might differentiate into cementoblasts when reimplanted with a dental substrate in vivo. Periodontal ligament cells exhibited no calcified tissue formation in vivo, but cells synthesized a connective tissue with orientated fiber bundles attached to both host bone and root, resembling periodontal ligament.

[The synthesis of collagenous and noncollagenous proteins by cells from the periodontium]. / Synthese kollagener und nicht-kollagener Proteine durch Zellen aus dem Parodont.

Synthesis of collagenous and noncollagenous proteins by cells originating from the alveolar bone (AB-cells) and from the periodontal ligament (PDL-cells) of 8 minipigs was analyzed in primary cell cultures. Incorporation of 3H-proline into proteins recovered from cell extracts showed, that 13.7% of protein synthesized by AB-cells and 8.0% of protein synthesized by PDL-cells were collagens. In both cell lines relative amounts of collagens synthesized decreased significantly on subculturing (AB-cells: 9.3%, PDL-cells: 6.0%). Preincubation of 2nd subculture AB-cells with beta-glycerophosphate had no significant effect on collagen synthesis. Considering the fact that relative amounts of collagen recovered from cell extracts represent only 10-20% of collagen recovered from whole culture (i.e. cells and culture medium), we suggest that collagen synthesis is an important component of in vitro-protein synthesis of cells originating from the alveolar bone and the periodontal ligament.

[Root canal preparation using Excimer lasers]. / Aufbereitung von Wurzelkanälen mit Excimer-Lasern.

As an alternative in endodontics to mechanical methods for root canal treatment, the use of a XeCl-excimer laser to prepare the canal wall was studied. In a light microscopic investigation undecalcified sections of laser-treated extracted human teeth showed that it was not possible to remove dentine in the root canal. Pulpal tissues remained in all wall areas. The available energy densities of this laser type seem to be not sufficient to ablate pulpal tissues or wall dentine.

Correlation between caries prevalence (DMFS) and periodontal condition (CPITN) in more than 2000 patients.

The CPITN (Community Periodontal Index of Treatment Needs) and DMFS (Decayed-Missing-Filled Surfaces) index were evaluated simultaneously to provide information on the mutual influences of periodontal disease and caries. With the aid of an electronic database system the data of the caries index and periodontal index of more than 2000 patients aged between 18 and 80 years were stored and calculated. As expected, the CPITN and DMFS values increased with age. When the CPITN was selected as a reference the DMFS was found to change with increasing CPITN. With the examination method used in this study no correlation could be established between the prevalence of caries and periodontal condition, although both conditions have a common aetiological factor: microbial plaque.