Cml. Bollen et al., THE INFLUENCE OF ABUTMENT SURFACE-ROUGHNESS ON PLAQUE ACCUMULATION AND PERI-IMPLANT MUCOSITIS, Clinical oral implants research, 7(3), 1996, pp. 201-211
Citations number
37
Categorie Soggetti
Engineering, Biomedical","Dentistry,Oral Surgery & Medicine
Bacterial adhesion to intra-oral, hard surfaces is firmly influenced b
y the surface roughness of these structures. Previous studies showed a
remarkable higher subgingival bacterial load on rough surfaces when c
ompared to smooth sites. More recently, the additional effect of a fur
ther smoothening of intra-oral hard surfaces on clinical and microbiol
ogical parameters was examined in a short-term experiment. The results
indicated that a reduction in surface roughness below R(a)=0.2 mu m,
the so-called ''threshold R(u)'', had no further effect on the quantit
ative/qualitative microbiological adhesion or colonisation, neither su
pra- nor subgingivally. This study aims to examine the long-term effec
ts of smoothening intra-oral hard transgingival surfaces. In 6 patient
s expecting an overdenture in the lower jaw, supported by endosseus ti
tanium implants, 2 different abutments (transmucosal part of the impla
nt): a standard machined titanium (R(a)=0.2 mu m) and one highly polis
hed and made of a ceramic material (R(a)=0.06 mu m) were randomly inst
alled. After 3 months of intra-oral exposure, supra- and subgingival p
laque samples from both abutments were compared with each other by mea
ns of differential phase-contrast microscopy (DPCM). Clinical periodon
tal parameters (probing depth, gingival recession, bleeding upon probi
ng and Periotest-value) were recorded around each abutment. After 12 m
onths, the supra- and subgingival samples were additionally cultured i
n aerobic, CO2-enriched and anaerobic conditions. The same clinical pa
rameters as at the 3-month interval were recorded after 12 months. At
3 months, spirochetes and motile organisms were only detected subgingi
vally around the titanium abutments. After 12 months, however, both ab
utment-types harboured equal proportions of spirochetes and motile org
anisms, both supra- and subgingivally. The microbial culturing (month
12) failed to detect large inter-abutment differences. The differences
in number of colony- forming units (aerobic and anaerobic) were withi
n one division of a logarithmic scale. The aerobic culture data showed
a higher proportion of Gram-negative organisms in the subgingival flo
ra of the rougher abutments. From the group of potentially ''pathogeni
c'' bacteria, only Prevotella intermedia and Fusobacterium nucleatum w
ere detected after anaerobic culturing and again the inter-abutment di
fferences were negligible. Clinically the smoothest abutment showed a
slightly higher increase in probing depth between months 3 and 12, and
more bleeding on probing. The present results confirm the findings of
our previous short-term study, indicating that a further reduction of
the surface roughness, below a certain ''threshold R(a)'' (0.2 mu m),
has no major impact on the supra- and subgingival microbial compositi
on.