Microbiological and clinical outcomes of fixed complete-arch mandibular prostheses supported by immediate implants in individuals with history of chronic periodontitis.

OBJECTIVES: The aim of this study was to assess the microbiological and clinical outcomes of immediate implants placed in chronically infected sockets for rehabilitation with fixed full-arch mandibular prostheses. MATERIAL AND METHODS: Fourteen individuals (mean age 60.14 ± 7.69 years) were enrolled in this investigation and followed up until 8 months of function. Microbiological (microbial count and profile) and clinical (probing depth, clinical attachment level, bleeding on probing, and bone resorption) parameters were conducted before teeth extraction (T0 - baseline) and after 4 (T1 ) and 8 (T2 ) months of loading. Thirty-nine microbial species including periodontopathogenic species and Candida spp. were detected and quantified by DNA checkerboard analysis. RESULTS: Moderate to high levels of pathogenic and non-pathogenic species were found colonizing teeth and implant-related sites. No significant differences in total or individual microbial counts and microbial profile were found over time (P = 0.4929). Probing depth values from teeth (T0 : 3.05 ± 1.45) were significantly higher when compared with implants (T1 : 1.81 ± 0.56; T2 : 1.66 ± 0.53; P < 0.0001). High percentages of bleeding sites were found for both teeth and implants, with the highest values recorded for teeth (P < 0.05). No significant differences were detected comparing marginal bone resorption over time. CONCLUSIONS: Total and individual counts of target species did not differ between teeth and implants for 8 months of investigation. The mean proportions of pathogenic and non-pathogenic species remained unaltered, and no clinical complications were reported over time. Data obtained suggest that immediate loading of complete mandibular prostheses retained by implants placed immediately after extraction may be a viable treatment option for edentulous individuals with previous history of periodontal disease.

Periodontal and Microbiological Profile of Intensive Care Unit Inpatients.

INTRODUCTION: The bidirectional relationship between the periodontal diseases and systemic diseases was attributed to the focal infection concept. The aims of this study were to assess the periodontal and microbiological profile of intensive care unit (ICU) inpatients submitted to orotracheal intubation, and classify them regarding gender, age group, ethnic, hospitalization reason and period, nosocomial infection occurrence, and death. MATERIALS AND METHODS: Inpatients were assessed, distributed into toothed and toothless groups. The periodontal clinical condition was assessed 24 hours after the ICU admission through plaque index, gum index, probing depth, and clinical level of insertion. All microbiological samples were collected on the 6th day of admission. These samples were collected from different intraoral sites, depending on the group: In the toothed group, samples were collected from gingival sulcus and in the toothless group, from buccal mucosa and tongue. Identification for Aggregatibacter actinomycetemcomitans (Aa), Porphyromonas gingivalis (Pg), and Tannerella forsythia (Tf) was accomplished and analyzed, using absolute quantification and specific primer pairs through an amplification system with probes. RESULTS: Forty subjects composed the sample: Gender characterized by 60% of male, 27.5% of all patients were older than 60, and 22.5% were hospitalized due to cerebrovascular accident. Regarding hospitalization period, 55% of patients were hospitalized for 6 days and 70% of them died during the period of hospitalization. Of inpatients, 40% presented periodontal disease and 100% presented dental biofilm on assessed sites. When assessing the microbiota, statistical significance was observed between Aa, Pg, and Tf, for both toothed and toothless group (p < 0.0001). CONCLUSION: Large quantities of Aa were found in samples of toothless inpatients, a fact that suggests that the oral environment, even without teeth, presents favorable conditions for bacterial biofilm formation with a related pathogenic potential. CLINICAL SIGNIFICANCE: The dental biofilm may comprise pulmonary pathogen colonies, promoting a perfect environment for their growth and development, facilitating the colonization of the lower airways, as well as colonization by bacteria originally from the oral cavity.

Biofilm formation of Candida albicans on the surface of a soft denture-lining material.

BACKGROUND: Soft denture lining-materials are more susceptible to microbial adhesion than hard denture base acrylic resin. Poor oral hygiene and Candida albicans infection are common among elderly denture wearers as these patients usually have difficulty in keeping them clean. PURPOSE: To evaluate the influence of the oral hygiene methods on the formation of a biofilm over a soft denture-lining material. MATERIAL AND METHODS: Twenty volunteers were randomly separated into two groups: G1 and G2. Ten volunteers performed daily hygiene of the prostheses with a soft toothbrush and toothpaste. The G2 performed a treatment identical to G1 but also immersed the prostheses in sodium hypochlorite 0.5% for 20 min, once a week. Quantification of the mean score values of biofilm formation at different times were statistically analysed using analysis of variance and Tukey's test (alpha = 0.05). RESULTS: G1 (0.65 +/- 0.52) showed the lowest mean score values of biofilm formation. There was statistical difference between G1 and G2. The highest mean score values were found at 6 weeks (1.3 +/- 1.08) and were statistically different from other times. CONCLUSION: The oral hygiene methods had a significant effect in the formation of the biofilm over a soft denture-lining material.

Correct complete denture rehabilitation, a chance for recovering abused tissues.

The prosthodontic treatment must provide for the edentulous patients bio-functional prosthetic restorations, bio-prophylactic for the surrounding tissues. In this aim, an edentulous patient must be submitted to a methodical clinical examination in order to establish the quality of hard and soft tissues, which will indicate the degree of difficulty of the prosthetic treatment. Additional investigation as a microbiologic examination and cephalometric radiographs can be useful in a modern investigation. In our daily practice, we are rarely confronted with a normal morphology of the denture bearing oral structures. The problem of managing abused tissues in a patient with morphologic abnormalities due to faulty prostheses is sometimes difficult to solve. Preventing the deterioration of oral status must be a condition in providing a chance for the success of the following rehabilitations, mainly in the situation when the complete edentulousness succeeds in a young or middle age patient.

Evaluation of peri-implant microbiota using the polymerase chain reaction in completely edentulous patients before and after placement of implant-supported prostheses submitted to immediate load.

PURPOSE: To evaluate, by means of the polymerase chain reaction (PCR), the presence of Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia in the mandibular arch of completely edentulous subjects before implant placement and 4 and 6 months after the placement of mandibular implant-supported fixed prostheses. MATERIALS AND METHODS: Fifteen patients had bacterial plaque collected with sterile paper points before implant placement (ie, when they were completely edentulous) and at 3 sites on the peri-implant sulci displaying the largest probing depths after placement of 5 implants. RESULTS: For the edentulous arch, A actinomycetemcomitans was detected in 13.3% of subjects, P intermedia was detected in 46.7% of subjects, and there was no detection of P gingivalis. After 4 and 6 months of implant placement, A actinomycetemcomitans was detected in 60% and 73.3% respectively; P intermedia in 46.7% and 53.3% respectively; and P gingivalis in 46.7% and 53.3%, respectively. DISCUSSION: Future diagnosis should not be restricted to distinguishing individuals at risk of peri-implant disease. Such individuals should be identified by the employment of microbiologic methods and knowledge of the multifactorial nature of the host response to the action of microorganisms. CONCLUSIONS: The longer the implants were in the oral cavity, the higher the occurrence of A. actinomycetemcomitans, P. gingivalis, and P. intermedia in the peri-implant sulci of completely edentulous patients rehabilitated with mandibular implant-supported fixed prostheses was, without any clinical or radiographic evidence indicating peri-implant disease in the studied period.

Salivary levels of mutans streptococci and lactobacilli in dentate 80- and 85-year-old Swedish men and women.

The number of Streptococcus mutans, Streptococcus sobrinus, and lactobacilli in whole stimulated saliva was examined in 130 dentate 80- and 85-yr-old persons. 88.5% were positive for mutans streptococci and 29% carried greater than 10(6) cfu per ml saliva. S. mutans was most frequently isolated and was found in 114 persons (88%) alone or in combination with S. sobrinus. S. sobrinus was detected in 33 persons (25%), who also showed significantly higher salivary numbers of both mutans streptococci and lactobacilli than persons from whom S. sobrinus was not isolated. The S. sobrinus carriers also had significantly lower stimulated saliva secretion rates than the non-carriers. 95% of the subjects had detectable levels of lactobacilli in saliva with 35% having greater than 10(5) cfu per ml saliva. When the subjects were divided into classes according to the number of intermaxillary contacts, i.e. the Eichner classification, the distribution of subjects with high and low salivary counts of cariogenic bacteria varied. Thus fewer subjects belonging to Eichner class A showed higher salivary numbers of mutans streptococci (14% had greater than 10(6) cfu/ml) as well as lactobacilli (21% had greater than 10(5) cfu/ml) than, for example, subjects belonging to Eichner class B (26% had greater than 10(6) cfu/ml of mutans streptococci, 35% had greater than 10(5) cfu/ml of lactobacilli). Subjects who carried a removable denture(s) had significantly higher salivary numbers of both mutans streptococci and lactobacilli than subjects without removable dentures.

New method for evaluation of tongue-coating status.

The purpose of this study was to determine the viability of Tongue Coating Index, which is a new method for evaluating tongue-coating status. To determine the reliability and reproducibility of our new evaluation criteria (Score 0: Tongue coating not visible; Score 1: Tongue coating thin, papillae of tongue visible; Score 2: Tongue coating very thick, papillae of tongue not visible), 10 observers evaluated 20 photographs of tongues. Each tongue surface was divided into nine sections. Observers evaluated each section according to our new criteria and each score for tongue-coating status was recorded in the pertinent section of the Tongue Coating Record form. They repeated the same evaluation 2 weeks after the first evaluation. The relationship between the scores obtained and number of oral microorganisms was investigated in 50 edentulous patients. Tongue coating was collected from the tongue surface after evaluation of tongue-coating status. The total number of anaerobic bacteria and the number of Candida species were counted from the specimens collected. Interobserver agreement and intraobserver agreement were 0.66 and 0.80 by Cohen's kappa, respectively. No significant difference was observed in the number of Candida species among the three scores. The number of total anaerobic bacteria, however, was significantly different among the scores (P < 0.05). Therefore, we conclude that our method for evaluating tongue-coating status offers new criteria that are superior in reliability and reproducibility, and that also reflect the total number of anaerobic bacteria present on the dorsum of the tongue.

Reliability of findings around healthy implants in association with oral hygiene measures: a clinical, microbiological, and immunological follow-up in edentulous patients.

OBJECTIVES: To assess the performance of clinical, microbiological, and immunological diagnosis of peri-implant health and the influence of professional hygiene measures on them. MATERIAL AND METHODS: Twenty-one edentulous patients with oral implants supporting a lower overdenture were followed up over 3 months beginning 1 week before their annual recall visit. Hygiene scores, probing depth, bleeding on probing (BOP), implant stability, gingival crevicular fluid (GCF) volume, sulcular interleukin-1beta (IL-1beta) and prostaglandin E2 (PGE2) concentrations, and relative concentrations of five bacterial species (polymerase chain reaction) were investigated. Measurement variation was assessed as a function of (a) intra- and (b) inter-examiner reliability, (c) inter-implant variation in each patient, (d) time, and (e) effect of hygiene measures by accuracy, repeatability, reproducibility, and visualization with the Bland and Altman Plot. RESULTS: Measurement means and accuracy (in parentheses) were as follows: GCF volume 1.5 microl (1.5), Interleukin-1beta 8 ng/ml (26), PGE2 63 ng/ml (185), bacteria sum score 0.2 (0.7), plaque score 1 (1), BOP score 0 (1), Periotest value -4 (3), resonance frequency analysis ISQ 66 (11), and pocket probing depth 2.3 mm (0.7). No finding exhibited any statistically significant measurement variation as explained by accuracy, repeatability, or reproducibility. Bland and Altman Plots revealed insufficient agreement for replicated BOP assessments. A short post-treatment reduction in plaque and BOP scores was visually apparent. Still, professional oral hygiene measures exerted no sustained influence on the clinical and biochemical appearance of the peri-implant tissues. CONCLUSION: All findings except BOP showed statistically acceptable repeatability and moderate vulnerability to influences present 'chairside' in clinical practice.

Microbiological and clinical outcomes and patient satisfaction for two treatment options in the edentulous lower jaw after 10 years of function.

BACKGROUND: Long-term data on microbiological and clinical outcome as well as on patient satisfaction after implant therapy in the edentulous mandible are limited. Especially comparisons between fixed full prostheses (FFPs) and overdentures (ODs), or between anchoring systems for the latter are scarce. AIM: This study aimed to evaluate both of these parameters at the 10-year follow-up in a group of fully edentulous patients rehabilitated via an OD or a FFP (the latter to allow inter-group comparison). MATERIAL AND METHODS: A total of 37 fully edentulous patients (25 ODs, 12 FFPs, age at implant installation ranged from 36 to 85 years) participated in this study. All subjects received their implants (Branemark System, Nobel Biocare AB, Gothenburg, Sweden) 10 years previously. For the ODs different attachment systems (bar, magnets, ball) had been applied that allowed a further intra-group comparison. At the follow-up visit, 10 years after the abutment insertion, a series of periodontal parameters were recorded, long-cone radiographs were taken and subgingival plaque samples were collected for analysis using checkerboard DNA-DNA hybridization. The clinical and radiographic data were recorded at abutment connection and after 1 and 10 years. RESULTS: After 10 years of loading, mean plaque and bleeding indices and changes in attachment or marginal bone level were not significantly different, neither between the OD and FFP group, nor within the OD group. The marginal bone loss between abutment connection and year 10 was 0.86 and 0.73 mm for OD and FFP groups, respectively. The subgingival microbiota at implant sites from all (sub)-groups was comparable, with low numbers of DNA counts (+/-10 x 10(5)) but high detection frequencies of Actinobacillus actinomycetemcomitans (>90%), Porphyromonas gingivalis (>85%) and Tannerella forsythensis (30%). The composition of the subgingival microbiota was influenced by probing depth and bleeding tendency. Patient satisfaction was very high for both types of prosthetic rehabilitation. The FFP group scored only slightly better for chewing comfort and general satisfaction. CONCLUSION: These data indicate that from the clinical and microbiological standpoint, as well as patient satisfaction, both an OD and a FFP offer a favourable long-term outcome.

Burning mouth sensation associated with fusospirochetal infection in edentulous patients.

Six middle-aged and elderly edentulous, systemically ill patients complaining of burning mouth sensation had a fusospirochetal infection of the oral mucosa. Metronidazole was successful in the treatment of three of these patients.

Periodontal status and serum antibody titers for Porphyromonas gingivalis fimbriae in a rural population in Japan.

BACKGROUND, AIMS: The present study was undertaken to assess the periodontal status of a rural Japanese population and to study the correlation between the periodontal status and the serum antibody titers for Porphyromonas gingivalis (Pg) fimbriae. METHOD: A total of 236 individuals were examined for their periodontal conditions by the use of the community periodontal index for treatment needs (CPITN), and serum antibody titers for Pg fimbriae in their peripheral blood samples were evaluated using the enzyme-linked immunosorbent assay. RESULTS: There was a substantially larger proportion of edentulous subjects in the age group older than 60 years. The remaining teeth were 24.1, 23.2, 11.1 and 10.1 per person in the 40-49, 50-59, 60-69 and > or = 70 age groups, respectively. The % of sextants with a CPITN code of missing sextant (MS) increased towards elderly and reached >60% in the age group of > or = 70 years, as the % of the CPITN 2, 1 or 0 sextant decreased. The % of CPITN 4 and 3 sextants did not differ between different age groups and were about 6-8% and 15-20%, respectively. The % of CPITN 1 or 0 sextants was higher in female subjects than in male subjects in the 60-69 and > or = 70 age groups, while the % of CPITN 4 or 3 sextants was higher in male subjects than in female subjects in all age groups. There was no significant difference between various age groups in the mean serum antibody titers for Pg fimbriae. The mean anti-Pg fimbriae antibody titers was significantly higher for the subjects with a maximum CPITN code 4 (max.-CPITN 4 subject) than for the subjects with lower maximum CPITN codes. The antibody titers varied extensively among the max.-CPITN 4 or 3 subjects, but not among the max.-CPITN 2/1/0 or MS subjects. CONCLUSIONS: The present study demonstrated that tooth loss is a remarkable event in elderly subjects and that oral prophylaxis and mechanical debridement should be mandatory in the population examined. It was also demonstrated that the serum antibody titers against Pg fimbriae could be useful for screening individuals with moderate to severe periodontitis.

Reproducibility of microscopic and cultural data in repeated subgingival plaque samples.

In association studies, micro-organisms can only be recognized as suspects for playing a major rôle in the development of a pathological environment, if their destructive action goes along with a marked proportional increase of their numbers or if their first detection can be related to the clinical onset of the disease. Limitations in the reproducibility of repeated samples have to be taken into account, when changes of the microbial composition of subgingival environments are to be studied, and when local clinical changes are to be related to shifts in the composition of the pertaining microbiological compartment. To study reproducibility, a total of 109 sites was sampled repeatedly with sterile paperpoints at an interval of 7 to 10 days in 24 patients suffering from periodontal disease and 12 edentulous patients wearing successful and failing osseointegrated titanium implants. Using continuous anaerobic techniques, the samples were cultured on nonselective and selective media and were studied by darkfield microscopy. Both the intertest-agreements of frequencies of detection (kappa-statistics) as well as the discrepancies of proportions of bacterial groups and selected bacterial species were determined. The standard deviation of proportional differences between first and second samples ranged between 6.4% (fusiform organisms) and 17.2% (coccoid cells) for darkfield parameters, between 4.3% (B. melaninogenicus on ETSA/Kana.) and 14.0% (B. gingivalis on ETSA/Kana.) for selected bacterial species and between 6.9% (gram-negative anaerobic cocci) and 24.0% (gram-positive facultative cocci) for bacterial groups classified according to gram stain characteristics and atmospheric growth conditions.(ABSTRACT TRUNCATED AT 250 WORDS)

Mutans streptococci and lactobacilli in the elderly.

The prevalence of salivary mutans streptococci and lactobacilli, salivary flow rate, and the type of dentition were studied in connection with a medical survey of 76-, 81-, and 86-yr-old inhabitants of Helsinki living at home. High bacterial counts were associated with low salivary flow rates. High counts of mutans streptococci (> 10(6) CFU/ml) were found in 68% of wearers of full dentures, as compared with 53% of subjects having natural teeth. High counts of lactobacilli (< 10(6) CFU/ml) were found in 44% of subjects having removable partial dentures and in 39% of subjects having natural teeth. The bacterial counts correlated neither with medicines taken daily nor with diseases among this population.

Pre- and post-implantation microbiota of the tongue, teeth, and newly placed implants.

OBJECTIVES: This investigation sought intra-oral sources of species colonizing dental implants. MATERIALS AND METHODS: Plaque samples were taken pre- and post-successful osseointegration from implants, teeth, and from tongues of 10 edentulous and 11 partially dentate subjects. Samples were assayed using whole genomic DNA probes in a checkerboard assay to 42 subgingival species. RESULTS: Similar prevalences and mean levels (10(3) to 10(4)) of microorganisms colonized implants and teeth. Species levels from tongue samples were higher than those of teeth and implants, although species prevalence was similar, suggesting that larger samples were obtained from the tongue. No significant differences were observed between the microbiota from the tongue of edentulous and partially dentate subjects. Most implant species were detected on tongue pre-implantation. In individual edentulous subjects, there were positive associations between Capnocytophaga ochracea and Campylobacter rectus from tongue and implant samples. In individual partially dentate subjects, there were positive associations between Fusobacterium nucleatum subsp. vincentii from tongue and implant samples, and Treponema denticola from implant and tooth samples taken at the same visit. CONCLUSION: This study indicated that the tongue, in addition to teeth, can be a source for species colonizing new implants.

Microbiota and crevicular fluid collagenase activity in the osseointegrated dental implant sulcus: a comparison of sites in edentulous and partially edentulous patients.

The soft tissues adjacent to osseointegrated dental implants (OII) were investigated using clinical, biochemical and microbiological methods. Tooth and implant crevices were compared in 15 partially edentulous patients, examining 28 peri-implant and 19 periodontal sites, and in 6 edentulous patients, examining 13 implant sites. Sites were classified by standard periodontal indices; the crevicular fluid flow determined; crevicular fluid was collected for collagenase assays; and the subgingival bacterial flora was examined and cultured. Differences in clinical parameters were noted in that implants had significantly less keratinized gingiva and deeper probing depths. Crevicular fluid was present in the OII sulcus but the crevicular fluid flow did not differ from that observed from tooth sites either in the partially edentulous or edentulous patients. Tissue collagenase activity and collagenase inhibitor were detected in the implant crevicular fluid and, as in periodontal sites, a strong inverse relationship was found between the levels of active collagenase and collagenase inhibitor. Microbiology included darkfield microscopy, anaerobic culturing for total colony forming unit counts and identification of black pigmented Bacteroides (BPB). Few differences were observed between implants and teeth in partially edentulous patients, indicating that crevices around teeth may act as reservoirs of bacteria which can colonize implant sites. A higher percentage of BPBs and wet spreaders (Capnocytophaga) was noted at partially edentulous implant sites when compared with edentulous implant sites, perhaps reflecting the lower numbers of periodontal pathogens present in edentulous mouths. Overall, the characteristics of implant sulci appear to be similar to periodontal sulci with respect to crevicular fluid flow and microflora.

High incidence of Staphylococcus aureus from dentures and tongues of maxillary resection patients.

The incidence and virulence of Staphylococcus aureus from upper dentures and tongues of maxillary resection and edentulous patients were examined. The incidence rates of S. aureus on dentures and tongues from the 8 maxillary resection patients were significantly higher than those from the 20 maxillary edentulous patients. Some S. aureus strains in both patient groups were resistant to antibiotics, and 1 methicillin-resistant S. aureus strain was isolated in each group. Exfoliative toxin was not produced, whereas diverse types of enterotoxin were detected in 4 of the 8 maxillary resection patients and in 3 of 13 maxillary edentulous patients. These findings show that S. aureus inhabits dentures and tongues of maxillary resection patients more often than those of maxillary edentulous patients and that some strains have potential virulence, suggesting that maxillary resection patients are potentially more exposed to a threat from S. aureus and would be the carriers.

Oral findings in irradiated edentulous patients.

11 edentulous patients (mean age 71.2 years) with oral or oropharyngeal malignancies were examined clinical and microbiologically before, during, and after receiving tumoricidal radiation doses (26.4-74 Gy) towards the head and neck regions. The effect of a supervised oral hygiene program and a saliva substitute (Va-OraLube) was studied. The 9 patients who survived the observation period, showed increased xerostomia and mucositis related to increased radiation. Radionecrosis or oral infections were not observed. The patients wore their dentures throughout the observation period and preferred to use the saliva substitute. The initial number of acidophilic bacteria was high, Candida albicans were present in low numbers and enteric bacteria occurred more frequently than normally. There was a reduction of micro-organisms after introduction of the hygiene program. It is concluded that careful planning of the radiotherapy, pre-radiation oral examination, denture control and instruction and an effective oral hygiene program are essential for the reduction of oral complications in edentulous patients receiving tumoricidal radiotherapy to the head and neck regions.

Effect of the application of a mucin-based saliva substitute on the oral microflora of xerostomic patients.

A cross-sectional study among 46 xerostomic patients was carried out to determine the influence of a mucin-based artificial saliva on the microflora of standardized oral washings. Patient and non-xerostomic control groups were formed according to the use of saliva substitute (ad libitum or from an intraoral reservoir) and dentition (dentate, edentulous, full dentures). Only few differences were observed among the subgroups based on dentition within a specified salivary group. However, the total number of microorganisms and the proportions of veillonellae, actinomycetes, streptococci and S. salivarius were significantly reduced in xerostomic patients not using artificial saliva, whereas lactobacilli, Candida and S. mitior were significantly increased compared to the control groups. Ad libitum use of artificial saliva had little effect, but semi-continuous wetting of the oral cavity through an intra-oral reservoir reversed the xerostomia-induced shifts in the indigenous microflora. However, no significant effect was observed on the proportions of lactobacilli and yeasts, leaving a potentially acidogenic flora.

Carriage of oral flora on irreversible hydrocolloid and elastomeric impression materials.

This study assessed the carriage and persistence of oral flora on irreversible hydrocolloid and elastomeric impression materials. In the first part of the study, a single isolate each of Streptococcus mutans, Escherichia coli, Staphylococcus aureus, and Candida albicans were inoculated onto each of two elastomeric and two irreversible hydrocolloid impression surfaces artificially created in vitro. Then the inoculum was discarded, samples of impression material (13 mm in diameter) were removed over a 5-hour period, and the remainder of viable organisms were estimated. In the second part of the study, impressions were made from 21 dentate and eight edentulous patients, and bacterial counts were estimated as described. The results showed twofold to fivefold retention of bacteria on the irreversible hydrocolloids compared with the elastomeric impression surfaces. With all impression materials, the number of viable bacteria retained within 5 hours decreased 65% to 98% except for the "disinfectant" irreversible hydrocolloid Blueprint Asept, which totally destroyed the organisms in less than 3 minutes. It is concluded that the total bacterial "load" on impression surfaces is relatively low and decreases rapidly after impression making. However, disinfection of impression surfaces should be mandatory to prevent cross-infection.