Clinical outcomes and supragingival microbiota analysis around dental implants and teeth in patients with a history of periodontitis: a preliminary study of 6 months follow-up.

OBJECTIVES: To investigate the supragingival microbiome surrounding dental implants and neighbouring tooth in periodontitis history and periodontally healthy patients. METHODS: Subjects with a history of periodontitis (test) and periodontally healthy subjects (control) received one of two types of dental implants with different surface characteristics: sandblasted acid-etched (SLA) or precision dimension laser-treated (PDL). Periodontal clinical measurements were collected at baseline (V1), 3 months after implant placement (V4), at zirconia crown placement (V6) and 3 months after zirconia crown placement (V8). Supragingival bacterial microbiota was studied using Illumina MiSeq sequencing. RESULTS: Supragingival microbial community on SLA implants in test group significantly differed to control group at V8 (p < 0.05). A longitudinal shift displaying microbial dysbiosis occurred on SLA implants (p < 0.05) and adjacent teeth (p < 0.05) among test patients from V6 to V8. On PDL implants and the adjacent tooth, no significant difference between test and control groups from V6 to V8 (p > 0.05). Co-occurrence network in test group of SLA implants and the adjacent tooth at V8 showed increased disease-associated bacteria and reduced health-associated bacteria. Health-associated bacteria were dominant in control group of SLA implants at V8. CONCLUSION: The surface characteristics and prosthetic components of dental implants may be important risk factors in patients with a history of periodontitis. CLINICAL RELEVANCE: Dysbiosis of supragingival microbiome may predispose dental implants to peri-implant diseases. Thus, a strict supportive periodontal care plan is imperative to prevent early onset of biological complications.

Marginal Adaptation and Microbial Leakage at Conometric Prosthetic Connections for Implant-Supported Single Crowns: An In Vitro Investigation.

Encouraging clinical results were reported on a novel cone-in-cone coupling for the fixation of dental implant-supported crowns (Acuris, Dentsply Sirona Implants, Mölndal, Sweden). However, the presence or absence of a microgap and a potential bacterial leakage at the conometric joint has not yet been investigated. A misfit and a resulting gap between the conometric components could potentially serve as a bacterial reservoir that promotes plaque formation, which in turn may lead to inflammation of the peri-implant tissues. Thus, a two-fold study set-up was designed in order to evaluate the bidirectional translocation of bacteria along conometrically seated single crowns. On conometric abutments filled with a culture suspension of anaerobic bacteria, the corresponding titanium nitride-coated (TiN) caps were fixed by friction. Each system was sterilized and immersed in culture medium to provide an optimal environment for microbial growth. Positive and negative controls were prepared. Specimens were stored in an anaerobic workstation, and total and viable bacterial counts were determined. Every 48 h, samples were taken from the reaction tubes to inoculate blood agar plates and to isolate bacterial DNA for quantification using qrt-PCR. In addition, one Acuris test system was subjected to scanning electron microscopy (SEM) to evaluate the precision of fit of the conometric coupling and marginal crown opening. Throughout the observational period of one week, blood agar plates of the specimens showed no viable bacterial growth. qrt-PCR, likewise, yielded a result approaching zero with an amount of about 0.53 × 10-4 µg/mL DNA. While the luting gap/marginal opening between the TiN-cap and the ceramic crown was within the clinically acceptable range, the SEM analysis failed to identify a measurable microgap at the cone-in-cone junction. Within the limits of the in-vitro study it can be concluded that the Acuris conometric interface does not allow for bacterial translocation under non-dynamic loading conditions.

Genome analysis and clinical implications of the bacterial communities in early biofilm formation on dental implants restored with titanium or zirconia abutments.

This cross-sectional study aimed to identify and quantify up to 42 target species colonizing the early biofilm of dental implants restored with titanium or zirconia abutments. A total of 720 samples from 20 healthy individuals were investigated. Biofilm samples were collected from the peri-implant sulci, inner parts of implants, abutment surfaces and prosthetic crowns over a functioning period of 30 days. Checkerboard DNA-DNA hybridization was used for microbial detection and quantitation. Clinical characteristics (probing depth, bleeding on probing, clinical attachment level and marginal bone loss) were also investigated during the monitoring period. Genome counts were low at the implant loading time point for both the abutment materials, and increased over time. Both the titanium and the zirconia groups presented similar microbial counts and diversity over time, and the microbiota was very similar to that colonizing the remaining teeth. Clinical findings were consistent with a healthy condition with no significant difference regarding marginal bone loss between the two materials.

Biofilms in restorative dentistry: A clinical report.

This clinical report describes the structure and characteristics of the biofilm formed under a cemented restoration, confirming the need to develop new cementation protocols to disrupt and minimize the formation of biofilm before cementing definitive restorations.

[Adhesion of Streptococcus mutans to removable denture crowns].

OBJECTIVE: To determine adhesion of Streptococcus mutans (S. mutans) to different kinds of removable denture crowns for the purpose of minimizing influence of removable denture on oral environment. METHODS: Three kinds of removable denture crowns (single color synthetic resin teeth, alloy pin porcelain tooth and minute color synthetic resin teeth) were adsorbed S. mutans for 24 h in sterile saliva, The adhered bacteria were counted by means of sonic oscillation and bacteria coating. RESULTS: Highest level of adhesion was found on ,the single color synthetic resin teeth was adsorbed mostly, followed by alloy pin porcelain teeth. Minute color synthetic resin teeth had far less adhesion than the others (P<0.01). CONCLUSION: Minute color synthetic resin teeth have less adhesion of S. mutans, which may be associated with their lower level of surface free energy.

[Oral microbiocenosis features of diabetic patients after orthopedic treatment with various types of crowns].

The article gives a detailed analysis of oral cavity microbiocenosis features of 36 patients with type II diabetes for 5 years. These data reflects microbiocenosis features before and after orthopedic treatment with metal-ceramic and pressed crowns. These results indicate that frequency of occurrence and the number of microorganisms of the genus Streptococcus, Staphylococcus (including S. aureus), Peptostreptococcus and Candida is significantly higher in patients after orthopedic treatment with pressed crowns than with metal-ceramic crowns. A high percentage of normal microflora, particularly lactobacilli (60%), was revealed on gingival mucosa in patients after orthopedic treatment with metal-ceramic crowns.

Microbial diversity of peri-implant biofilms on implant fixed bar and telescopic double crown attachments.

One of the principal problems in oral implantation is inflammation of peri-implant hard and soft tissues caused by bacterial biofilms. The purpose of the present study was to evaluate the microbial diversity of peri-implant biofilms on 2 different implant-anchored attachment types in vivo. Samples of peri-implant sulcus fluid were collected from 8 patients with implant-supported bar attachments and 8 patients with implant-anchored telescopic double crown attachments. Samples of sulcus fluid of the adjacent teeth were also collected from the partially edentulous patients with implant fixed telescopic double crowns. The mixed amplicons of 16S rRNA fragments of different bacterial origins were separated by use of single-strand conformation polymorphism analysis to identify the predominant bacterial genera. With 3.5 ± 2.1 different predominant bacterial genera in the sulcus fluid surrounding implant-supported bar attachments and 6.3 ± 3.1 different predominant genera in the sulcular fluid of implant-anchored double crown attachments, the differences were not statistically significant (P = .11). The microbial diversity in the sulcus fluid surrounding the remaining dentition was similar to that of the implant fixed telescopic attachments (6.3 ± 2.1). Aside from host response and other individual factors, the microbial diversity of peri-implant biofilms seems to be impaired by cofactors such as the possibility of cleaning the implant-supported supraconstructions and the different plaque-retaining sites. Nevertheless, these differences do not lead to statistically significant differences in the microbial diversity of peri-implant plaques.

Clinically acceptable restorations may be a hotbed for cariogenic microbes.

OBJECTIVE: The aim of this study was to investigate the cross-sectional association of dental restorations with salivary cariogenic pathogens among the elderly to establish effective parameters of caries risk for this population. MATERIALS AND METHODS: Stimulated whole saliva was collected from 289 community-dwelling older adults (66.2 ± 3.9 years old) who had 20 or more teeth. Salivary levels of three cariogenic bacteria (Streptococcus mutans, Streptococcus sobrinus and lactobacilli) were estimated using quantitative polymerase chain reaction (real-time PCR) method. RESULTS: The mean number of residual teeth was 26.4, and restored teeth with crowns, inlays and composite resin were 7.35, 3.88 and 0.68, respectively. The number of crowns correlated positively with salivary S. mutans, S. sobrinus and lactobacilli. Multiple linear regression analyses showed that the number of restored teeth with crowns was independently associated with salivary S. mutans, S. sobrinus and lactobacilli after controlling for age, gender, number of residual teeth and salivary flow rate. Salivary flow rate was independently associated with salivary S. mutans and lactobacilli. CONCLUSION: The number of crowns had an association with salivary levels of cariogenic bacteria, suggesting that this parameter may be a caries risk indicator for the elderly population.

Microbiological and biochemical effectiveness of an antiseptic gel on the bacterial contamination of the inner space of dental implants: a 3-month human longitudinal study.

Microbial penetration inside the implants internal cavity produces a bacterial reservoir that is associated with an area of inflamed connective tissue facing the fixture-abutment junction. The aim of this clinical trial is to evaluate the effectiveness of a 1 percent chlorhexidine gel on the internal bacterial contamination of implants with screw-retained abutments and on the level of AST secreted in peri-implant crevicular fluid. Twenty-five patients (aged 29 to 58 years) each received one implant. Three months after the end of the restorative treatment, and immediately after a clinical and radiographic examination and the abutment removal, microbiological samples were obtained from the internal part of each fixture and biochemical samples were collected by peri-implant sulci. The patients were then divided into two groups: the control (CG; n=10) and test (TG; n=15) groups. The CG had the abutment screwed into place and the crown cemented without any further intervention. In contrast, before the abutment placement and screw tightening, the TG had the internal part of the fixture filled with a 1 percent chlorhexidine gel. Three months later, the same clinical, microbiological and biochemical procedures were repeated in both groups. Total bacterial count, specific pathogens and AST activity were detected. The clinical parameters remained stable throughout the study. From baseline to the 3-month examination, the total bacterial counts underwent a significant reduction only in the TG. In contrast, the AST activity showed a significant increase in the CG. The administration of a 1% chlorhexidine gel appears to be an effective method for the reduction of bacterial colonization of the implant cavity and for safeguarding the health status of peri-implant tissue over a 3-month administration period.

Bacterial leakage and bending moments of screw-retained, composite-veneered PEEK implant crowns.

Due to its elastic modulus close to bone, the high-performance material PEEK (polyetheretherketone) represents an interesting material for implant-supported dental prostheses. Besides a damping effect of masticatory forces, it might have a sealing effect against bacterial leakage of the implant-abutment interface (IAI). So far, PEEK has only been used for provisional implant crowns. Therefore, the aim of the study was the evaluation of the bacterial tightness of screw-retained PEEK crowns on titanium implants with conical IAI during masticatory simulation and subsequent bending moment testing. Ten screw-retained implant crowns in the shape of an upper central incisor consisting of a PEEK crown framework veneered with composite were connected to NobelActive RP titanium implants (4.3 × 11.5 mm, Nobel Biocare AB, Göteborg, Sweden) with a tightening torque of 15 Ncm. Prior to tightening, the interior of the implant was inoculated with a bacterial suspension of Enterococcus faecium. The specimens were overmolded with indicating agar (Kanamycin-Aesculin-Azid-Agar (KAAA), Oxoid Limited, Basingstoke United Kingdom), that turns black in contact with E. faecium. The specimens were subjected to a cyclic masticatory simulation whereby a force of 50 N cm was applied at an angle of 30° to the implant axis for 1.2 million cycles. Afterwards, the specimens were subjected to a static loading test according to ISO 14801:2007 to determine the bending moment. During masticatory simulation neither a loosening of the implant screws nor any damage to the veneer or the PEEK framework occurred. Furthermore, no bacterial leakage could be observed in any of the specimens. The average maximum bending moment was measured at 352.13 ±â€¯48.96 N cm. Regarding masticatory forces, PEEK implant crowns seem to be applicable as definitive implant-supported restorations. Furthermore, the bacterial tightness of the IAI of screw-retained one-piece PEEK implant crowns is advantageous compared to superstructures of conventional materials. Further studies are necessary to substantiate the clinical significance of these findings.

Intraoral versus extraoral cementation of implant-supported single crowns: Clinical, biomarker, and microbiological comparisons.

OBJECTIVES: Implant supported single metal-ceramic crowns cemented either extraorally or intraorally were comparatively evaluated by clinical, radiologic, biomarker, and microbiological parameters. MATERIALS AND METHODS: Twelve patients with bilateral single tooth gap in the maxillary posterior region received two locking-taper implants; 4.5 mm width, 8 mm length. Selection of intraoral (IOC) or extraoral cementation (EOC) using screwless titanium abutments was done randomly. Peri-implant crevicular fluid (PICF), gingival crevicular fluid (GCF) samples were collected from the implants, adjacent teeth, and bleeding on probing, soft tissue thickness, keratinized tissue width were recorded before starting the prosthetic procedures (baseline) and 3, 6 months after implant loading. Crestal bone loss was measured on radiographs taken immediately and 6 months after cementation. Cytokine levels, amounts of bacteria were determined in PICF/GCF samples. Data were tested by appropriate statistical analyses. RESULTS: Clinical findings were similar in the crowns cemented extraorally or intraorally at all times (P < .05). PICF and GCF data were similar. At 3 month, interleukin-17E and osteoprotegerin levels were lower in the intraorally cemented crowns. CONCLUSION: Extraorally and intraorally cemented crowns exhibited similar crestal bone loss after loading. Higher amount of osteoprotegerin at 3 month at the EOC than the IOC sites might bode well for good osseointegration.

Prevention of bacterial leakage into and from prefabricated screw-retained crowns on implants in vitro.

Previous in vitro studies have shown that a mean gap of less than 4 microns between prefabricated crowns and implants of the Ha-Ti implant system is not a barrier to infiltration by Staphylococcus aureus. These studies confirmed earlier in vivo work showing that a multitude of oral microorganisms could colonize and infiltrate these gaps. In the present investigation, 30 Ha-Ti implant-crown assemblies were tested for bacterial leakage after the gaps were sealed with the chlorhexidine-containing varnish Cervitec. S. aureus leakage into the totally submerged test specimens was detected in 1 of 5 samples incubated for 4 weeks, while no leakage was detected in specimens incubated for 3, 5, 6, 7, and 8 weeks. When the sealed test specimens were partially submerged (that is, excluding the screw hole of the crown) and incubated for 3 to 11 weeks, none of the internal surfaces of the 30 test specimens manifested contamination. The clinical relevance of gap sealing in maintaining inflammation-free marginal mucosa and in achieving clinically successful treatment of peri-implantitis has yet to be determined.

In vivo effectiveness of silicone gel sheets as barriers at the inner microgap between a prosthetic abutment and an external-hexagon implant platform.

PURPOSE: Bacterial penetration and colonization of the microgap at the implant-abutment interface have been reported in several studies. The aim of this study was to evaluate the effectiveness of placing a silicone membrane between the abutment and the implant platform in an attempt to seal the interface. MATERIALS AND METHODS: A total of 15 external-hex implants were placed in 10 patients with clinically healthy peri-implant tissues, and all of the patients had ceramic prosthetic crowns. Samples were collected from the microgaps before, 30 days after, and 90 days after insertion of a silicone membrane. Bacterial DNA was extracted and submitted in triplicate to polymerase chain reaction using primers specific for four peri-implant pathogens: Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, and Tannerella forsythia. RESULTS: In the initial samples, a positivity of 52% was found, which was different from that found in samples collected after 30 days (32%) and 90 days (27%) after insertion of the membrane. CONCLUSION: It was evident that the silicone membrane reduced, but did not prevent, penetration of these species into external-hex implants.

Sealing properties of three luting agents used for complete cast crowns: a bacterial leakage study.

OBJECTIVE: To assess the sealing properties of three different luting materials used for cementation of full cast crowns on extracted human premolars. METHODS: Thirty noncarious human premolars were prepared in a standardized fashion for full cast crown restorations. All margins were placed in dentin. After impressions of the preparations, stone dies were fabricated on which copings were waxed, which were cast in type III alloy using standardized laboratory methods. Teeth were randomly assigned to three groups of 10 samples each (n=10), for which the following cements were used: 1) a resin-modified glass ionomer cement, Rely X Luting Plus (3M ESPE, St Paul, MN, USA); 2) a self-adhesive resin cement, Maxcem Elite (Kerr Corporation, Orange, CA, USA); and 3) a glass ionomer cement, Ketac Cem (3M ESPE), the latter used as control. After cementation the samples were allowed to bench-set for 10 minutes, stored in water at 37°C, subjected to thermal cycling (2000×, between 5°C and 55°C, dwell time 35 seconds), and then stored in sterile phosphate buffer for seven days at 37°C. Subsequently, the occlusal surface was carefully reduced until the dentin was exposed. Finishing on wet sand paper removed the gold flash caused by grinding. After sterilization, the specimens were subjected to bacterial microleakage in a dual chamber apparatus for 60 days. Bacterial leakage was checked daily. Data were analyzed using the Kaplan-Meier survival test. Significant pairwise differences were analyzed using the log-rank test followed by Fisher exact test at a p<0.05 level of significance. RESULTS: Rely X Luting Plus showed the lowest microleakage scores, which statistically differed significantly from Maxcem Elite and Ketac Cem (p<0.05). CONCLUSIONS: Rely X Luting Plus cement displayed significantly lower microleakage scores than a self-adhesive resin-based and conventional glass ionomer cement.

Comparative study on the microbial adhesion to preveneered and stainless steel crowns.

CONTEXT: The extensive plaque formation on dental restorations may contribute to secondary caries or periodontal inflammation. Therefore, it is important to know how different types of dental restorations may prevent or promote the accumulation of microorganisms. AIMS: The aim of this in vivo study was to evaluate the adhesion of Streptococcus mutans to preveneered and stainless steel crowns (SSCs) and to evaluate the effects of these restorations on the gingival health and oral hygiene. MATERIALS AND METHODS: Twenty patients (age 3-5 years) were selected from the outpatient clinic of the pedodontics department, Faculty of Oral and Dental Medicine, Cairo University. The selected patients had (dmf) index for primary dentition ≤4, including lower right and left first primary molars. Each tooth was pulpotomy-treated and restored with either type of crowns (split-mouth technique). Then, ten swabs from the buccal mucosa, preveneered crown, and SSC surfaces were taken from each patient. Also, the gingival index (GI) and oral hygiene index (OHI-S) were measured at different times during the study. Mitis Salivarius Bacitracin agar (MSBA) was used as a selective medium for S. mutans growth. MSBA plates were taken in candle jar and incubated aerobically in 37°C for 48 h. Finally, bacteria were counted and expressed in colony forming unit (CFU). RESULTS: After 1, 2, and 4 weeks, mucosa and crown swabs of preveneered crown showed statistically significant higher mean CFU counts than SSC. Through the whole study period, the two restorations revealed a statistically significant decrease in mean CFU counts. Also, there was a statistically significant positive (direct) correlation between OHI-S, GI, and S. mutans counts on both restorations. CONCLUSIONS: The adhesion of S. mutans to preveneered crowns was higher than to SSC. Full mouth rehabilitation led to significant decrease in S. mutans count in the short term. An increase in S. mutans counts is associated with an increase in OHI-S and GI.

Antimicrobial efficacy of chemical disinfectants on contaminated full metal crowns.

Prosthetic restorations that have been tried in the patient's mouth are potential sources of infection. In order to avoid cross-infection, protocols for infection control should be established in dental office and laboratory. This study evaluated the antimicrobial efficacy of disinfectants on full metal crowns contaminated with microorganisms. Full crowns cast in a Ni-Cr alloy were assigned to one control group (n=6) and 5 experimental groups (n=18). The crowns were placed in flat-bottom glass balloons and were autoclaved. A microbial suspension of each type of strain - S. aureus, P. aeruginosa, S. mutans, E. faecalis and C. albicans- was aseptically added to each experimental group, the crowns being allowed for contamination during 30 min. The contaminated specimens were placed into recipients with the chemical disinfectants (1% and 2% sodium hypochlorite and 2% glutaraldehyde) for 5, 10 and 15 min. Thereafter, the crowns were placed into tubes containing different broths and incubated at 35ºC. The control specimens were contaminated, immersed in distilled water for 20 min and cultured in Thioglycollate broth at 35ºC. Microbial growth assay was performed by qualitative visual examination after 48 h, 7 and 12 days. Microbial growth was noticed only in the control group. In the experimental groups, turbidity of the broths was not observed, regardless of the strains and immersion intervals, thus indicating absence of microbial growth. In conclusion, all chemical disinfectants were effective in preventing microbial growth onto full metal crowns.

Effect of liquid-polish coating on in vivo biofilm accumulation on provisional restorations: part 1.

OBJECTIVE: Biofilm accumulation on provisional restorations may affect the surrounding tissues' integrity. The purpose of this study was to test in vivo biofilm formation on polymethyl methacrylate (PMMA) self-cured acrylic resin provisional crowns. METHOD AND MATERIALS: Three types of PMMA surfaces were tested: (1) polished, (2) polished and coated with bonding agent, and (3) polished and coated with light-cured liquid polish. After 12 hours in the oral cavity, the crown was removed and examined by confocal laser scanning microscope (CLSM) and scanning electron microscope (SEM). RESULTS: Biofilm, 250 Mum thick, was observed with CLSM on the polished acrylic surface. Significantly less bacterial accumulation was observed on the crowns coated with bonding agent, whereas no biofilm was observed on the crowns coated with liquid polish (P <.001). SEM examination confirmed these findings. CONCLUSIONS: Bonding resin or liquid polish coatings significantly reduce early biofilm formation, which in turn might affect the overall plaque accumulation on provisional restorations.

A retrospective clinical, radiographic and microbiological study of periodontal conditions of teeth with and without crowns.

The aim of this study was to evaluate retrospectively the periodontal conditions of teeth with fixed crowns that had been in place from 3 to 5 years before the study was conducted. Forty individuals were recalled for a follow-up visit. Full-mouth clinical examinations were carried out and Visible Plaque Index (VPI), Gingival Bleeding Index (GBI), Probing Pocket Depth (PPD), and clinical attachment level (CAL) were assessed in 6 sites per tooth. Parallel radiographs were also taken and blindly analyzed by a digital caliper (distance between the apex and the bone crest). BANA tests were performed. A contra-lateral sound tooth was considered the control. Mean values were obtained and Wilcoxon and paired sample t tests were used to compare the test and control sites. Crowns had a mean VPI value of 30.42% as compared to 49.17% for sound teeth. The GBI was 33.33% and 26.25% for test and control teeth respectively. Assessment of PPD revealed values of 2.30 and 2.14 mm, and assessment of CAL revealed averages of 2.02 and 1.89 mm for test and control teeth respectively. The mean values for radiographic distances were 12.73 and 13.67 mm, and for the BANA test, 67.50 and 50.00 for sound and crowned teeth, respectively. Statistically significant differences were observed for all parameters except for CAL and for the BANA test. It may be concluded that, with the methods used in the present study, crowns may be associated with more signs of inflammation, however not with periodontal breakdown.

Mutans streptococci and lactobacilli in plaque on a leucite-reinforced dental ceramic and on a calcium aluminate cement.

In this in vivo study, the proportions of mutans streptococci and lactobacilli in plaque were examined (1) on proximal surfaces of bonded, leucite-reinforced ceramic crowns and (2) on class V restorations of calcium aluminate cement (CAC). The examined proportions were intraindividually compared with those of resin composite and enamel. Mutans streptococci and lactobacilli in samples from plaque that was accumulated for 10 days on the following surfaces were determined by cultivation on blood agar plates and species-selective plates: (1) proximal leucite-reinforced ceramic crown, class II composite and enamel (n=11); and (2) class V restoration of CAC and composite, and enamel (n=17). Mutans streptococci and lactobacilli in the samples were distributed in three groups: 0, >0-1, and >1% of total bacteria. The surfaces with detected mutans streptococci were similarly distributed between the materials and enamel. The highest proportion of mutans streptococci and lactobacilli were observed on ceramic followed by composite and enamel. A higher proportion of lactobacilli, but not of mutans streptococci, was detected on enamel compared to CAC and composite. However, no significant differences were found between the surfaces. Conclusively, the materials investigated did not show different relative proportions of mutans streptococci and lactobacilli in plaque, compared to enamel.