In vivo study of the initial bacterial adhesion on different implant materials.

OBJECTIVE: Biofilm formation on implant materials plays a major role in the aetiology of periimplantitis. The aim of this study was to examine in vivo the initial bacterial adhesion on six different implant materials. METHODS: The implant materials Ti-m, TiUnite®, ZiUnite®, ATZ-m, ATZ-s, TZP-A-m were tested using bovine enamel slabs as controls. All materials, fixed on splint systems, were examined after 30 min and 120 min of oral exposure. DAPI staining was used for quantitative analysis of the initially adherent microorganisms. Initial adherent microorganisms were visualised by fluorescence In situ-hybridisation (FISH) and quantified by confocal laser scanning microscopy (CLSM). The targets of the oligonucleotide probes were Eubacteria, Veillonella spp., Fusobacterium nucleatum, Actinomyces naeslundii and Streptococcus spp. RESULTS: DAPI analysis showed that increasing the time of oral exposure resulted in an increasing amount of initial adherent bacteria. The highest level of colonisation was on ZiUnite®, with the lowest occurring on the bovine enamel, followed by Ti-m. This early colonisation correlated significantly with the surface roughnesses of the materials. FISH and CLSM showed no significant differences relating to total bacterial composition. However, Streptococcus spp. was shown to be the main colonisers on each of the investigated materials. CONCLUSION: it could be shown that within an oral exposure time of 30 min and 120 min, despite the salivary acquired pellicle initial biofilm formation is mainly influenced directly or indirect by the material surface topography. Highly polished surfaces should minimise the risk of biofilm formation, plaque accumulation and possibly periimplantitis.

Biofilm formation and composition on different implant materials in vivo.

Biofilm formation was evaluated on the following titanium and zirconia implants in vivo: machined titanium (Ti-m), modified titanium (TiUnite), modified zirconia (ZiUnite), machined alumina-toughened zirconia (ATZ-m), sandblasted alumina-toughened zirconia (ATZ-s), and machined zirconia (TZP-A-m). Bovine enamel slabs were used as controls. Surface morphologies were examined by atomic force (AFM) and scanning electron microscopy (SEM). The surface wettability was also determined. Twelve healthy volunteers wore a splint system with the tested materials. After 3 and 5 days the materials were examined by fluorescence in situ hybridization (FISH) and confocal laser scanning microscopy (CLSM). The levels of Streptococcus spp., Veillonella spp., Fusobacteriaum nucleatum, and Actinomyces naeslundii were quantitatively determined. The biofilm thickness was found to be between 19.78 and 36.73 µm after 3 days and between 26.11 and 32.43 µm after 5 days. With the exception of Ti-m the biofilm thickness after 3 days was correlated with surface roughness. In addition to Streptococcus spp. as the main component of the biofilm (11.23-25.30%), F. nucleatum, A. naeslundii, and Veillonella spp. were also detected. No significant differences in biofilm composition on the implant surfaces could be observed. In total, the influence of roughness and material on biofilm formation was compensated by biofilm maturation.

Structure and in vitro cytocompatibility of the gastropod shell of Helix pomatia.

Distinguishing features of biological constructions are high stability and adaptation to their environment. Beside biocompatibility, nontoxicity and degradability these characteristics are demanded for new biomaterials in the field of tissue engineering. This study investigated the chemical composition, the organization and the in vitro osteoconductive potential of the terrestrial gastropod shell (Helix pomatia) on CAL72 and human osteoblast-like cells. Chemical composition of the biomaterial was examined by X-ray diffraction (XRD) and scanning electron microscopy (SEM) was performed to analyze the architecture of the snail shell and the morphology of the seeded cells. A double staining procedure (FDA/PI) and a proliferation test (EZ4U) assessed the viability of the cells. Microscopical images showed the multilayered architecture of the aragonite shell with hexagonal crystals on the inner side. The cells spread well on the biomaterial and the highest proliferation rate could be measured with CAL72 cells on the inner shell surface. The osteoconductive effects of this natural biomaterial could encourage further experiments in the field of tissue engineering.

[Prosthetic treatment of a six-year-old child with hypodontia. A case report]. / Prothetische Versorgung eines 6-jährigen Kindes mit Hypodontie. Ein Fallbericht.

The prosthetic treatment of young patients with congenital missing of several teeth is a challenge for the dentist. An early prosthetic management with regard to function, phonetics, esthetics is important to ensure a normal psychological development of these children and to promote a normal tooth and jaw development. On the basis of this case report about the prosthetic rehabilitation of a 6-year-old patient with congenital hypodontia of the primary and the permanent dentition, we give an overview of the literature available about this topic. A restorative dental management with removable prosthodontic appliances is described, and the prosthetic therapeutic alternatives are discussed.

[Guided bone regeneration around dental implants using a bioabsorbable membrane. A pilot investigation in experimental animals]. / Geführte Knochenregeneration um dentale Implantate mit einer bioresorbierbaren Membran. Eine tierexperimentelle Pilot-Untersuchung.

The aim of this experimental investigation was to evaluate the effect of guided bone regeneration around immediately placed implants using different barrier membranes. Five adult fox hounds were used in this investigation. After extraction of all premolars in the lower jaw, implant osteotomies in the regions of the former premolars and additional buccal bone defects (5 mm x 5 mm) were created. Subsequently, the implants were placed. The defects were treated with one of the following three modalities: (a) guided bone regeneration, using a bioinert expanded polytetrafluoroethylene membrane, (b) no membrane application and (c) guided bone regeneration, using a bioabsorbable membrane made from a synthetic copolymer of lactide and glycolide. After a healing period of six months, the animals were sacrificed and the implants with the surrounding tissues processed for histologic evaluation. The clinical pretreatment defects between the different treatment groups were not statistically different (bioinert membrane group: 4.8 mm; control group: 4.3 mm; bioabsorbable membrane group: 4.9 mm). The remaining histological defects after a healing period of 6 months amounted to 3.2 mm for the nonresorbable group, to 5.6 mm for the control and to 6.3 mm for the bioabsorbable group. A significant difference was observed between the bioinert membrane group and the other two groups. The mineralized bone-to-implant contact in the bioinert membrane group was 52%, in the control group 47% and in the bioabsorbable membrane group 43.3%. The values were not statistically significant different. The results of this study indicate that a partial bone regeneration with bioinert e-PTFE membranes around immediately placed implants is possible. The utilized bioabsorbable polylactide/polyglycolide membrane did not show any bone regenerative effect, and the results did not differ from the control group without membrane application.