***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: THE STUDY ASSESSES IN VIVO the surface roughness necessary to reduce plaque colonization on titanium after 24 hours . Three groups of 16 titanium disks were assigned to 3 different polishing groups ( A , B , and C ) . The roughness was evaluated with a laser profilometer and the morphology with a scanning electron microscope ( SEM ) . Eight volunteers were enrolled and two stents were applied in the m and ibular posterior region of each . Each stent supported 3 disks , one per group . The volunteers suspended oral hygiene for 24 hours , after which the stents were removed ; one was processed for evaluation of the adherent biomass and the other for SEM study . On each specimen a global area of 100 x 125 microns was examined with SEM . The area was composed of five 20 x 25 microns r and omly selected fields . For each field the density of bacteria and the morphotypes were recorded . The data quoted for the global area are cumulative of those observed in the 20 x 25 microns fields . Group A had a significantly smoother surface than groups B and C. The adherent microbial biomass determination and SEM evaluation revealed that group A contained less bacteria than the roughest group . The bacterial population was composed of cocci in group A , and of cocci and short and long rods in groups B and C. We conclude that a titanium surface with Ra < or = 0.088 microns and Rz < or = 1.027 microns strongly inhibits accumulation and maturation of plaque at the 24-hour time period and that such smoothness can be achieved in transgingival and healing implant components BACKGROUND Periodontitis and peri-implantitis are linked to the presence of several key pathogens . The treatment of these infectious processes therefore involves the reduction/eradication of bacteria associated with periodontitis . METHODS This prospect i ve , split-mouth , single-blind study followed the colonization of ' pristine ' sulci created in 42 partially edentulous patients during implant surgery ( e.g. abutment connection ) . The hypothesis was that the composition of the maturing subgingival plaque in these ' fresh ' peri-implant pockets would soon ( within 2 weeks ) be comparable to the subgingival microbiota of teeth with similar clinical parameters ( reference sites ) , including the presence of bacteria associated with periodontitis . Per patient , four subgingival plaque sample s were taken from shallow and medium pockets around implants ( test sites ) , and teeth within the same quadrant ( undisturbed microbiota as control sites ) , 1 , 2 , 4 , 13 , 26 and 78 weeks after abutment connection , respectively . The sample s were analysed by either checkerboard DNA-DNA hybridization , or cultural techniques , or real-time polymerase chain reaction ( PCR ) for intra-subject comparisons ( teeth vs. implant , for comparable probing depths ) . RESULTS Checkerboard DNA-DNA hybridization and real-time PCR revealed a complex microbiota ( including several pathogenic species ) in the peri-implant pockets within 2 weeks after abutment connection . After 7 days , the detection frequency for most species ( including the bacteria associated with periodontitis ) was already nearly identical in sample s from the fresh peri-implant pockets ( 5 % and 20 % of the microbiota belonging to red and orange complex , respectively ) when compared with sample s from the reference teeth . Afterwards ( e.g. between weeks 2 and 13 ) , the number of bacteria in peri-implant pockets only slightly increased ( + /-0.1 log value ) , with minor changes in the relative proportions of bacteria associated with periodontitis ( 8 % and 33 % of the microbiota belonging to red and orange complex , respectively ) . Although small differences were seen between teeth and implants at week 2 with cultural techniques , a striking similarity in subgingival microbiota was found with this technique from month 3 on , with nearly identical detection frequencies for bacteria associated with periodontitis for both abutment types . CONCLUSIONS This study indicates that the initial colonization of peri-implant pockets with bacteria associated with periodontitis occurs within 2 weeks BACKGROUND : If an implant with a rough surface is exposed to the oral cavity , it may accumulate greater amounts of plaque than a smooth surface , which may lead to severe problems with mucositis and peri-implantitis . The purpose of the present paper was to investigate the early inflammatory response to mucosa-penetrating abutments prepared with varying surface roughness . METHODS : Nine patients had all five of their original abutments exchanged to test abutments for a 4-week period . The test abutments were prepared with five different roughnesses . The surface roughness was measured with an optical profilometer . At the end of the test period , clinical evaluation was performed ; the health of the surrounding mucosa , the amount of accumulated plaque and marginal bleeding were registered . One biopsy was taken from each test abutment . Qualitative and quantitative histological evaluations were performed . RESULTS : There was a statistically significant difference between patients regarding the amount of accumulated plaque on the abutment surfaces and inflammatory cells , but no difference between the surface modifications in relation to plaque accumulation or number of inflammatory cells . CONCLUSION : No relation was found between inflammatory response and abutment surface roughness after an evaluation time of 4 weeks in a human test model The roughness of intraoral hard surfaces plays an important role in bacterial adhesion and colonization . Earlier studies have shown that rough surfaces accumulate up to 25 times more subgingival plaque than do smooth sites . In the present study , the influence of surface smoothing was studied . In six partially edentulous patients waiting for a fixed prosthesis supported by endosseous titanium implants , four titanium abutments with different surface roughness were r and omly placed . After 1 month of intraoral exposure , subgingival plaque sample s from each abutment were compared within each patient by means of differential phase-contrast microscopy . After 3 months , supragingival and subgingival plaque sample s were taken from all abutments for differential phase-contrast microscopy and culturing . Probing depth , recession , and bleeding upon probing were scored at the same visit . Differential phase-contrast microscopy showed that subgingivally , only the two roughest abutments harbored spirochetes after 1 month . After 3 months , subgingivally , the composition of the flora showed little variation on the different abutment types , although spirochetes were only noticed around the roughest abutments . Anaerobic culturing result ed in comparable amounts of colony-forming units for all abutment types , both supragingivally and subgingivally . Subgingivally , the microbiologic composition did not show major interabutment differences . Clinical ly , small differences in probing depth were observed . The roughest abutment showed some attachment gain ( 0.2 mm ) during 3 months , whereas all other abutments had an attachment loss ranging from 0.8 to greater than 1 mm . The results indicate that a reduction in surface roughness ( less than a roughness of 0.2 micron ) had no major effect on the microbiologic composition , supragingivally or subgingivally . These observations indicate the existence of a threshold roughness below which no further impact on the bacterial adhesion and /or colonization should be expected . However , clinical evaluation seems to indicate that a certain surface roughness is necessary for increased resistance to clinical probing Bacterial adhesion to intra-oral , hard surfaces is firmly influenced by the surface roughness to these structures . Previous studies showed a remarkable higher subgingival bacterial load on rough surfaces when compared to smooth sites . More recently , the additional effect of a further smoothening of intra-oral hard surfaces on clinical and microbiological parameters was examined in a short-term experiment . The results indicated that a reduction in surface roughness below R(a ) = 0.2 microns , the so-called " thresholds R(a ) " , had no further effect on the quantitative/qualitative microbiological adhesion or colonisation , neither supra- nor subgingivally . This study aims to examine the long-term effects of smoothening intra-oral hard transgingival surfaces . In 6 patients expecting an overdenture in the lower jaw , supported by endosseus titanium implants , 2 different abutments ( transmucosal part of the implant ) : a st and ard machined titanium ( R(a ) = 0.2 microns ) and one highly polished and made of a ceramic material ( R(a ) = 0.06 microns ) were r and omly installed . After 3 months of intra-oral exposure , supra- and subgingival plaque sample s from both abutments were compared with each other by means of differential phase-contrast microscopy ( DPCM ) . Clinical periodontal parameters ( probing depth , gingival recession , bleeding upon probing and Periotest-value ) were recorded around each abutment . After 12 months , the supra- and subgingival sample s were additionally cultured in aerobic , CO2-enriched and anaerobic conditions . The same clinical parameters as at the 3-month interval were recorded after 12 months . At 3 months , spirochetes and motile organisms were only detected subgingivally around the titanium abutments . After 12 months , however , both abutment-types harboured equal proportions of spirochetes and motile organisms , 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 within one division of a logarithmic scale . The aerobic culture data showed a higher proportion of Gram-negative organisms in the subgingival flora of the rougher abutments . From the group of potentially " pathogenic " bacteria , only Prevotella intermedia and Fusobacterium nucleatum were detected for anaerobic culturing and again the inter-abutment differences were negligible . Clinical ly , 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 microns ) , has no major impact on the supra- and subgingival microbial composition The purpose of this study was to characterize and compare by scanning electron microscopy ( SEM ) the maturation of supragingival microbial plaque on enamel and smooth titanium and that of subgingival plaque on cementum , plasma-sprayed titanium and hydroxyapatite surfaces . Specimens ( 6.5 x 2 x 1 mm ) were obtained from titanium implants with smooth transmucosal collars and plasma-sprayed endosseous posts of titanium or hydroxyapatite .  Unerupted third molars were sectioned to similar dimensions that included equal lengths of enamel and root surface . Ten patients with post-treatment pocket depths of > 6 mm on 3 non-adjacent teeth were selected and each had 1 set of the 3 specimen types bonded by r and om assignment to the selected teeth . Specimens were positioned so that enamel and /or smooth titanium surfaces were supragingival and cementum and titanium or hydroxyapatite plasma-sprayed surfaces were subgingival . Patients were instructed to stop oral hygiene , after which 2 specimen sets were removed at 1 , 3 , 5 , 7 and 10 days . Two specimens of each type were examined by SEM at each time interval for supra- and subgingival plaque . The sequence of appearance of various microbial morphotypes in supra- and subgingival plaque was similar regardless of surface . In both supra- and subgingival plaque , depending on time interval , cocci , rods of various lengths , filamentous organisms , fusiforms , spirochetes and corn-cob formations were observed . Mineralized plaque was noted on most subgingival specimens by day 10 . These observations indicate that surface of natural teeth , smooth titanium and plasma-sprayed titanium and hydroxyapatite support the maturation of microbial plaque with the successive inclusion of a variety of morphotypes OBJECTIVE To study the influence of perfluoroalkylsiloxane ( PA ) surface modification of  silicone rubber voice prostheses on biofouling . DESIGN Placebo-controlled clinical trial . SETTING Tertiary referral center , with specialization in head and neck cancer treatment . PATIENTS Eighteen consecutive patients with laryngectomies and experienced in the use of a voice prosthesis who visited the outpatient clinic for prosthesis replacement . MATERIAL Eighteen partially surface-modified voice prostheses  ( 3 with short-chain PAs [ 1 fluorocarbon unit ] and 15 with long-chain PAs [ 8 fluorocarbon units ] ) were inserted via the patients ' tracheoesophageal shunts and remained in place for 2 to 8 weeks . INTERVENTION Replacement of the prostheses . MAIN OUTCOME MEASURES Evaluation of biofilm formation on short- and long-chain PA-modified and original silicone rubber surfaces on the esophageal side of the voice prosthesis . RESULTS The planimetrical biofilm scores of the surfaces of all 3 short-chain PA-treated voice prostheses indicated more biofouling on the treated surfaces than on the untreated surfaces of the same prostheses . For the long-chain PA-treated prostheses , the planimetrical biofilm scores , as well as the numbers of colony-forming units per cm(-2 ) for bacteria and yeasts , indicated less biofouling on the treated side than on the control side for 9 of the 13 prostheses that could be analyzed ( 2 were lost to analysis ) . Identical fungal strains , mainly C and ida sp , were isolated from biofilms on each side of the esophageal flange . CONCLUSIONS Chemisorption of long- 
    Output:
    
RESULTS From a series of split-mouth studies , it could be concluded that both an increase in surface roughness above the R(a ) threshold of 0.2 microm and /or of the surface-free energy facilitates biofilm formation on restorative material s. When both surface characteristics interact with each other , surface roughness was found to be predominant .
The biofilm formation is also influenced by the type ( chemical composition ) of bio material or the type of coating .
Extrapolation of data from studies on different restorative material s seems to indicate that transmucosal implant surfaces with a higher surface roughness/surface free energy facilitate biofilm formation