The evaluation of the transport medium for extracted premolars prior to cryopreservation: a systematic literature review

Prior to cryopreservation, a tooth is transported from a contaminated oral environment to the tooth bank. Our objective was to identify all studies reporting or investigating a transport protocol prior to the cryopreservation of teeth, in terms of decontamination of the subjects. The systematic literature search (1970-2017) was based on MEDLINE via PubMed, Web of Science and the Cochrane Library. The reference lists of the included studies and the Science Citation Index were used for hand searching (snowballing). Only studies reporting the transport conditions of the transplant were included. Language restrictions for English, Dutch or French were applied. The search led to 14 eligible studies. Almost all studies were laboratory studies, so the methodological quality of evidence was low. The majority of the included studies was performed by only five different research groups and the number of subjects varied between 1 and 120 teeth. In general, the teeth were stored in a tissue culture medium supplemented with fetal calf serum and/or different combinations of antibiotics and/or antimycotics. The teeth were transported cooled (4 °C) or at room temperature, for a period of time not exceeding 24 h. Only three studies reported the irrigation of the teeth with phosphate buffered saline prior to the transport. The optimisation of the decontamination during transport was investigated in three studies (from 1971, 1980 and 1982). It was concluded that the literature on this topic is scarce, and the decontamination protocol for teeth, prior to cryopreservation has not been validated recently.

Bioactivity Studies of β-Lactam Derived Polycyclic Fused Pyrroli-Dine/Pyrrolizidine Derivatives in Dentistry: In Vitro, In Vivo and In Silico Studies

The antibacterial activity of β-lactam derived polycyclic fused pyrrolidine/pyrrolizidine derivatives synthesized by 1, 3-dipolar cycloaddition reaction was evaluated against microbes involved in dental infection. Fifteen compounds were screened; among them compound 3 showed efficient antibacterial activity in an ex vivo dentinal tubule model and in vivo mice infectious model. In silico docking studies showed greater affinity to penicillin binding protein. Cell damage was observed under Scanning Electron Microscopy (SEM) which was further proved by Confocal Laser Scanning Microscope (CLSM) and quantified using Flow Cytometry by PI up-take. Compound 3 treated E. faecalis showed ROS generation and loss of membrane integrity was quantified by flow cytometry. Compound 3 was also found to be active against resistant E. faecalis strains isolated from failed root canal treatment cases. Further, compound 3 was found to be hemocompatible, not cytotoxic to normal mammalian NIH 3T3 cells and non mutagenic. It was concluded that β-lactam compound 3 exhibited promising antibacterial activity against E. faecalis involved in root canal infections and the mechanism of action was deciphered. The results of this research can be further implicated in the development of potent antibacterial medicaments with applications in dentistry.

Randomized controlled trial: lip piercing: the impact of material on microbiological findings

PURPOSE

The purpose of this study was to investigate whether there are microbiological differences in bacterial samples collected from labial piercings made of different materials.

METHODS

Sterile piercings of 4 materials were randomly allocated to 80 pierced subjects. After 2 weeks, microbiologic samples were collected and processed by checkerboard DNA-DNA hybridization methods. Wilcoxon signed ranks and Mann-Whitney tests were used for statistical analysis (adjustment for multiple comparisons).

RESULTS

There were no statistically significant differences between material groups in relation to baseline data. In samples from stainless steel piercings, the total microbial load was significantly higher than the other materials (P<.05). Ten (mainly periopathogenic) species were found at significantly higher levels (P<.001) on steel than on polypropylene and/or polytetrafluoroethylene piercings.

CONCLUSIONS

Labial piercings made of stainless steel could promote the development of a pathogenic biofilm.

Microbiologic findings 1 year after partial- and full-mouth scaling in the treatment of moderate chronic periodontitis

OBJECTIVE

To investigate the impact on microbiologic variables of full-mouth scaling (FMS) and conventional scaling and root planing (cSRP) after 12 months.

METHOD AND MATERIALS

In a prospective randomized controlled clinical study, 37 volunteers with moderate chronic periodontitis were treated by FMS or by cSRP in two sessions at 4-week intervals. Clinical attachment level, probing depth, and bleeding on probing were recorded at baseline as well as at 6 and 12 months. Four subgingival plaque samples were taken from the deepest sites in premolars and molars at baseline and after 12 months. Pooled sample analysis was performed using real-time polymerase chain reaction for the identification of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola.

RESULTS

At baseline, the bacterial load of A actinomycetemcomitans was significantly higher in the cSRP group compared to the FMS group (P = .042). In the cSRP group, this load decreased significantly (P = .011), leading to similar quantities of A actinomycetemcomitans in both groups. Further, significant reductions in frequency were found in the FMS group for T forsythia and P gingivalis and in the cSRP group for A actinomycetemcomitans and T denticola.

CONCLUSION

The data suggest that both therapy modalities lead to similar effects on target periodontal pathogen species. FMS compared to cSRP was not favorable in reduction of periodontopathogens.

Comparative analysis of long-term biofilm formation on metal and ceramic brackets

OBJECTIVE

To test the null hypothesis that stainless steel and ceramic brackets show no differences in biofilm adhesion.

MATERIALS AND METHODS

Twenty adolescents (6 boys, 14 girls) who had received fixed orthodontic therapy for 18.9 ± 3.2 months were divided into a metal and a ceramic bracket group. Thirty brackets per group were taken from central incisors, canines, and second premolars and quantitatively analyzed for biofilm coverage with the Rutherford backscattering detection method. Five micrographs were obtained per bracket with views from the buccal, mesial, distal, gingival, and occlusal aspects, resulting in a total of 300 images. Biofilm formation between groups was compared using the Mann-Whitney U-test (α = .05).

RESULTS

Total biofilm formation was 12.5% ± 5.7% (3.3 ± 1.6 mm(2)) of the surface on metal and 5.6% ± 2.4% (1.5 ± 0.6 mm(2)) on ceramic brackets. Differences between groups were statistically significant (P < .05). A pairwise comparison of biofilm formation revealed significantly lower biofilm formation on ceramic brackets with respect to intraoral location (central incisor, canine, second premolar) and bracket surface (buccal, mesial, distal).

CONCLUSIONS

The hypothesis was rejected. The results indicate that ceramic brackets exhibit less long-term biofilm accumulation than metal brackets.

DIAGNOdent measurements of cultures of selected oral bacteria and demineralized enamel

OBJECTIVE

Carious tissue fluoresces with a wavelength different from sound tissue when stimulated by light with a wavelength of 655 nm. This difference is thought to have a bacterial origin rather than indicating demineralization. This study aimed to measure fluorescence emitted by normal cultivable caries-associated bacterial flora and typical porphyrin-producing bacteria with DIAGNOdent, and to verify earlier findings that demineralization of the dental hard tissue does not affect DIAGNOdent readings.

MATERIAL AND METHODS

Bacterial samples were collected from five occlusal caries lesions in three subjects. From these, mixed anaerobic flora, Lactobacilli and mutans Streptococci were cultured in up to three different kinds of culture medium. Colonies of Lactobacilli and mutans Streptococci were also measured after transferring them to glass slides. Laboratory teaching strains of Prevotella spp., Porphyromonas gingivalis and Actinomyces odontolyticus were cultured anaerobically and fluorescence measured directly after an appropriate incubation period. Sound enamel surfaces of 15 extracted premolars were demineralized and changes in fluorescence measured.

RESULTS

DIAGNOdent readings > 20 were only obtained from young colonies of Prevotella and from colonies of mutans Streptococci cultured on mitis-salivarius-bacitracin agar. Higher measurements were obtained as the bacterial colonies aged. Lower measurements were obtained after transferring colonies to glass slides. Demineralization of enamel did not affect the DIAGNOdent measurements.

CONCLUSIONS

The change in fluorescence measured with DIAGNOdent has a bacterial origin rather than occurring as a result of demineralization. The measurements are presumably dependent on bacterial metabolites rather than bacteria themselves, and probably record synergistic effects during the carious process rather than the quantity or species of bacteria involved.

Bacterial microleakage and post space timing for two endodontic sealers: an in vitro study

AIM

The effects of immediate versus delayed post space preparation on the apical seal using resin and zinc oxide eugenol (ZOE) sealers were compared by a bacterial leakage model.

METHODOLOGY

Eighty-six premolars were randomly assigned to four experimental groups of 20 teeth. Three teeth were assigned to each control group, either positive (filled only with guttapercha) or negative (not obturated but root surfaces completely covered). Obturation was achieved by gutta-percha with resin or gutta-percha with a ZOE sealer and lateral condensation technique. Post space was prepared either immediately or a week later, while the obturated teeth had been stored in 100 percent relative humidity at 37 degrees C. The teeth were inserted into plastic vials and suspended in glass bottles. All teeth were covered with cyanoacrylate and layers of nail varnish but the apical 3 mm and were sterilized using gamma rays. Phenol red lactose broth was inoculated into the vials. Staphylococcus epidermidis was introduced into the root canal access of the teeth. Turbidity of the broth in the vials (discoloration) was evaluated daily for a period of 70 days. The data was analyzed statistically with Pearson Chi Square and two ways with ANOVA at 45 days and 70 days.

RESULTS

When the depth of time was considered, the mean time of leakage showed no differences between immediate and delayed preparation for resin AH26 versus ZOE Dorifil at 45 and 70 days (p = 0.37 and p = 0.217, respectively). In 45 days, considering the number of teeth with leakage, there was a significant difference between immediate preparation and delayed preparation in AH26 sealer groups (p = 0.028). No difference was present between immediate and delayed preparation groups for the ZOE sealer groups (p = 0.14).

CONCLUSION

According to the results of this study and despite type of sealer, immediate post space preparation did not achieve better sealing than delayed post space preparation. Resin AH26 showed the least leaking teeth in 45 days, but it made no difference in 70 days.

Regional differences within the dentition for plaque, gingivitis, and anaerobic bacteria

OBJECTIVE

This investigation assessed regional differences in dental plaque and gingivitis within the human dentition in conjunction with microbiological analyses of dental plaque.

METHODS

Forty-one adults (23 males and 18 females; age range 19-44 years) were enrolled, and a calibrated dental examiner completed whole mouth examinations for dental plaque (PI) and gingivitis (GI) using the Turesky modification of the Quigley-Hein Index (TMQH) and the L6e-Silness (LS) Index, respectively. Dental plaque samples were collected from the anterior surfaces and posterior teeth to determine viable anaerobic bacteria. During this visit, subjects underwent a whole mouth dental prophylaxis and were provided a marketed fluoride dentifrice for twice-daily oral hygiene. Subjects were recalled on day 15 and day 30 for whole mouth assessments of PI and GI, followed by the collection of dental plaque from the anterior and posterior teeth for microbiological analyses during these visits.

RESULTS

Low plaque and gingival scores were common on anterior surfaces, in contrast to greater frequencies of higher PI and GI scores on the posterior regions or the entire dentition. Correspondingly, mean scores for PI and GI were significantly lower among the anterior surfaces in comparison to all other regions of the mouth (posterior, Ramfjord surfaces, or the entire dentition) over each phase of the study (p < 0.0001). While prophylaxis resulted in lower clinical scores from baseline to the day-15 recall visit (p < 0.05), anterior surfaces demonstrated lower scores than posterior regions during this recall visit (p < 0.05). Although dental plaque scores increased from the day-15 to the day-30 evaluations, gingival scores maintained broad reductions, with anterior scores consistently lower than the corresponding posterior regions (p <0.05). Microbiological analyses indicated significantly lower numbers of viable bacteria from the anterior surfaces in comparison to posterior regions at both recall visits (p < 0.05).

CONCLUSION

Anterior surfaces routinely demonstrated lower levels of dental plaque scores than the other regions of the dentition. Higher gingival inflammation levels were also correlated with increased plaque deposits associated with posterior teeth. Microbiological analyses confirm clinical observations with significantly higher numbers of viable bacteria in the dental plaque collected from the posterior regions. The human dentition demonstrates significant regional differences in the prevalence of dental plaque, gingivitis, and corresponding anaerobic bacteria, with posterior surfaces consistently reporting higher scores than the anterior regions. These consistent differences should be taken into account in performing plaque and gingivitis studies when assessing the efficacy of oral health products for controlling dental health.

Reaction of the Lateral Periodontium of Dogs’ Teeth to Contaminated and Noncontaminated Perforations Filled with Mineral Trioxide Aggregate

It has been shown that the mineral trioxide aggregate (MTA) used to seal lateral/furcal perforations stimulates the deposition of newly formed cementum. Nevertheless, when the site of the perforation is contaminated, the healing process might occur under less favorable conditions. This study evaluated the repair healing process of noncontaminated and contaminated lateral perforations filled with MTA and the effect of previously filling the contaminated perforations with a bactericidal agent. Thirty lateral root perforations were prepared in endodontically treated dog's teeth, thus forming 3 groups with 10 specimens each. In group 1 the perforations were immediately sealed with MTA. In group 2 the perforations were left open for 7 days and thereafter sealed with MTA. In group 3 the perforations were left open for 7 days, filled temporarily with a calcium hydroxide-based paste for 14 days, and then sealed with MTA. The animals were killed after 90 days, and the pieces were prepared for histomorphologic and histomicrobiologic evaluations. The statistical analysis showed that group 1 had significantly better repair than groups 2 (P < .05) and 3 (P < .05), which validates the superior results obtained when MTA was immediately used to seal root perforations. Groups 2 and 3 had statistically similar repair to each other (P > .05). There were a larger number of cases of complete or partial biologic seal in group 1 compared with the contaminated groups. It might be concluded that the lateral root perforations sealed with MTA after contamination presented worse repair than the noncontaminated, immediately sealed perforations. The temporary filling with a bactericidal agent (calcium hydroxide-based paste) did not improve the repair of perforations exposed to contamination, and the contaminated groups presented similar results to each other.

Bacterial microleakage of barrier materials in obturated root canals

The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarboxylate cement, resin modified glass ionomer cement, and flowable composite resin) used as a base over obturated root canals were evaluated during a 5-month period. Sixty single-rooted mandibular premolars were obturated with cold lateral compaction of gutta-percha. The teeth were randomly divided into five groups of 10 teeth each and positive and negative control groups of five. The access openings were filled with one of the tested barrier materials in four groups. In group 5, no barrier material was placed. Samples were incorporated in a model system using Staphylococcus epidermidis as a microbial marker. Results were analyzed with Kaplan-Meier survival analysis (p = 0.05). The sealing ability of all tested materials was better when compared with group 5 (no barrier material) (p < 0.05). Within the limitations of this study, the glass ionomer cement leaked significantly less when compared with the flowable composite resin (p < 0.05).

A comparative study on the disinfection potentials of bioactive glass S53P4 and calcium hydroxide in contra-lateral human premolars ex vivo

AIM

To evaluate the effects of bioactive glass S53P4 versus calcium hydroxide when used as dressings in contra-lateral human premolars infected with Enterococcus faecalis ATCC 29212.

METHODOLOGY

Pairs of contra-lateral premolar teeth plus single control premolars were obtained from 23 individuals aged 10-26 years undergoing orthodontic treatment. Root canals of teeth with fully formed apices (nine contra-lateral pairs, seven controls) were instrumented using a size 60 FlexoFiles 2 mm short of canal length. Canals with open apices (six contra-lateral pairs, four controls) were circumferentially instrumented using a FlexoFile. Root canals were rinsed with 1% sodium hypochlorite and 10% citric acid. Teeth were then suspended in tryptic soy broth (TSB) and autoclaved. Positive controls and study teeth were infected with E. faecalis ATCC 29212 for 2 weeks in TSB, while negative controls were kept in sterile TSB. Subsequently, contra-lateral premolars were dressed with bioactive glass S53P4 (BAG) or calcium hydroxide suspensions for 10 days. Dentine samples were obtained from teeth with fully formed apices using ISO-size 70, 80 and 90 FlexoFiles to working length and cultured. Teeth with open apices were fixed, fractured and examined using scanning electron microscopy (SEM).

RESULTS

Calcium hydroxide had a strong antibacterial effect and was significantly more effective than BAG in preventing residual bacterial growth (P < 0.01). SEM analysis revealed apparent substance-specific modes of action.

CONCLUSIONS

Calcium hydroxide was an effective disinfectant in human teeth.

Antibacterial Activity of 2% Chlorhexidine Gluconate and 5.25% Sodium Hypochlorite in Infected Root Canal: In Vivo Study

In this study, the antibacterial activity of the different antibacterial solutions using as root canal irrigant was compared in the teeth with pulpal necrosis and with periapical pathosis. Thirty root canals of incisors and premolars of 20 patients were used. Before and after the root canal preparation, two canal samples were obtained by a harvesting method using a sterile paper point in the first appointment. During the biomechanical preparation, both irrigant solutions were used for each tooth which were randomly divided into two groups. Last samples were also obtained before the root filling procedure. Samples obtained from the root canals were subjected to microbiologic processing, including anaerobic incubation on trypticase soy agar for 5 to 7 days. After counting of CFU on the plates, we concluded that both chlorhexidine gluconate and sodium hypochlorite were significantly effective to reduce the microorganisms in the teeth with necrotic pulp, periapical pathologies, or both, and could be used successfully as an irrigant solution.

A new in vivo interdental sampling method comparing a daily flossing regime versus a manual brush control

OBJECTIVE

The impact of flossing the interdental space is typically assessed by visual methods of questionable reliability, such as clinician observations and evaluations for scoring of plaque on visual tooth surfaces. The objective of this study was to develop and validate a method to measure interproximal quantities of dental plaque, thereby permitting quantitative evaluations of between-teeth cleaning and biofilm removal.

METHODOLOGY

Laboratory studies were performed correlating the quantity of bacteria to the amount of measured protein in a sample using a standardized protein assay (Bio-Rad Protein Assay) and samples containing single bacterial species and saliva/bacterial pellets. Analysis of the plaque was standardized against a bovine serum albumin (BSA) control. Pilot studies helped develop a technique for hygienist-applied interproximal flossing, reducing contamination from saliva and other possible sources of indeterminate error. Repeated sampling experiments were carried out to optimize the technique needed to remove the majority of quantifiable plaque, the best choice of flossing material, and establish the technique for collection. A pilot clinical trial assessed the benefits of daily flossing in reducing measurable quantities of interproximal plaque using the developed method. Thirty-nine subjects had six interdental sites (distributed across all four quadrants, pre-molar and molar boundaries) sampled on either side, over a three-week treatment period, in two balanced and equally sized treatment groups, with twice-daily manual brushing with or without daily flossing.

RESULTS

Laboratory studies confirmed the accuracy of the protein detection kit in assaying bacterial plaque loads from single species or complex biofilms. In pilot developmental screens, single flossing sweeps with appropriate dental floss were sufficient to remove the majority of quantifiable biomass from interproximal sites. The clinical study demonstrated that after three weeks, interdental plaque in floss users was significantly reduced versus baseline scores. Non-floss users showed no significant reduction. In direct comparison, less interdental plaque was recovered from subjects who had followed a daily flossing regime compared to subjects who had used a manual toothbrush alone (p = 0.0866).

CONCLUSION

The sampling method quantified the cleaning effects of daily flossing on interproximal plaque levels. Daily flossing significantly reduced the amount of plaque found between the teeth compared to a manual brushing regimen alone. This new method should be useful in future studies on the evaluation of mechanical or chemical means of interproximal plaque control.

Resolution of persistent periapical infection by endodontic surgery

AIM

To examine the surfaces of a root tip removed during surgical endodontic treatment for the presence of microorganisms.

SUMMARY

The present clinical case illustrates an endodontic retreatment of a maxillary premolar tooth with a fistula and periapical reaction. The case was under treatment for 1 year, during which an intracanal medicament was replaced several times. As the lesion did not decrease and exudate was persistent through the fistula and root canal, root end resection with root end filling was performed. Microbiological samples were collected from the fistula, where Propionibacterium acnes, a species associated with endodontic failures, was detected by appropriate anaerobic technique. The resected root apex was observed by scanning electron microscopy (SEM), which revealed cocci and fungal forms surrounding one of the foramina. After 12 months, the periapical lesion had reduced.

Bacterial colonization during de novo plaque formation

OBJECTIVE

To determine microbial changes that occur during plaque formation in a dentition free of gingival inflammation.

MATERIAL AND METHODS

Ten subjects were recruited. The study included one preparatory period (2 weeks) and a plaque accumulation period (4 days). The volunteers exercised proper tooth cleaning methods, were scaled and received repeated professional mechanical tooth cleaning during the preparatory period. During the plaque accumulation period, the participants abstained from plaque control measures. Plaque was scored on the approximal surfaces of maxillary and mandibular premolars on Days 0, 1, 2 and 4 using a scale from 0 to 5 and according to the criteria of the Quigley and Hein Plaque Index (QHI). Supragingival plaque samples were obtained from the same intervals and surfaces and evaluated using a checkerboard DNA-DNA hybridization technique.

RESULTS

The mean QHI increased from 0 to 1.6 (Day 4). The total number of organisms on Day 0 averaged 140 x 10(5) and increased to about 210 x 10(5) after 4 days without oral hygiene. The most dominant species on Day 0 were members of the genus Actinomyces. These organisms comprised almost 50% of the microbiota evaluated. None of the Actinomyces species increased significantly during the 4 days. Some Streptococcus species increased significantly over time as well as species of the genera Capnocytophaga, Campylobacter, Fusobacteria and Actinomyces actinomycetemcomitans.

CONCLUSION

In the present investigation, the preparatory phase established a situation with minimal gingival inflammation and close to zero amounts of dental plaque. The Day 0 plaque samples exhibited high proportions of Actinomyces species. During the 4 days of no oral hygiene, there was a small increase in total numbers of organisms as well as a modest increase in the proportion of "disease-associated" taxa such as species of the "orange complex" species.

Formation of Streptococcus mutans biofilm following toothbrushing with regular and whitening toothpastes

PURPOSE

To examine the effect of toothbrushing with different brands of regular (Meridol, Colgate) and whitening toothpaste (Pearl Weiss, Rembrant, Email Diamant) on bacterial adhesion onto enamel surfaces in vitro.

MATERIALS AND METHODS

Extracted intact human teeth were brushed twice a day, for 3 minutes with the tested toothpaste for a period of 7 days. Sucrose dependent adhesion of Streptococcus mutans to the tested teeth was measured using pre-radioactive labeled bacteria.

RESULTS

S. mutans adhered more to enamel surfaces, pre-brushed with the tested toothpastes, than to teeth which were not brushed. Different profiles of bacterial adhesion were recorded. Both Diamant and Rembrant toothpastes increased bacterial affinity toward the enamel surface as compared to the other toothpastes. Meridol and Pearl Weiss demonstrated a similar adhesion effect as the etching control while brushing with Colgate demonstrated the least bacterial adhesion.

Antimicrobial efficacy of various root canal preparation techniques: an in vitro comparative study

In this study, we compared the antimicrobial efficacy of various root canal preparation techniques and instruments in the root canals of 40 human first maxillary premolars extracted for orthodontic reasons. After extirpation of the pulp, teeth were sterilized in an autoclave. Then, the root canals were infected with Enterococcus faecalis suspension and the teeth incubated at 37 degrees C for 24 h. Thereafter, the teeth were divided into five groups: preparation with K-file or K-Nitiflex file (step-back technique; groups 1 and 2), K-reamer (standardization technique; group 3), irrigation only (group 4), and no treatment (group 5). Before and after treatments, samples were taken for culture. Results were evaluated after 24-h incubation in E67 selective culture medium. We observed a considerable reduction in bacterial population after mechanical preparation. No significant differences were seen among the efficacy of the various preparation techniques and files used.

Microbial profile on metallic and ceramic bracket materials

The placement of orthodontic appliances creates a favorable environment for the accumulation of a microbiota and food residues, which, in time, may cause caries or exacerbate any pre-existing periodontal disease. The purpose of the present study was to compare the total bacterial counts present on metallic and ceramic orthodontic brackets in order to clarify which bracket type has a higher plaque retaining capacity and to determine the levels of Streptococcus mutans and Lactobacillus spp on both types of brackets. Thirty-two metallic brackets and 24 ceramic brackets were collected from orthodontic patients at the day of debonding. Two brackets were collected from each patient; one from a maxillary central incisor and another from a maxillary second premolar. Sixteen patients who used metallic brackets and 12 patients who used ceramic brackets were sampled. Bacterial populations were studied using "checkerboard" DNA-DNA hybridization, which uses DNA probes to identify species in complex microbial samples. The significance of differences between groups was determined using the Mann-Whitney U-test. Results showed no significant differences between metallic and ceramic brackets with respect to the caries-inducing S mutans and L acidophilus spp counts. Mean counts of 8 of 35 additional species differed significantly between metallic and ceramic brackets with no obvious pattern favoring one bracket type over the other. This study showed higher mean counts of Treponema denticola, Actinobacillus actinomycetemcomitans, Fusobacterium nucleatum ss vincentii, Streptococcus anginosus, and Eubacterium nodatum on metallic brackets while higher counts of Eikenella corrodens, Campylobacter showae, and Selenomonas noxia were found on ceramic brackets.

Shoulder pain relieved by root canal

The authors report a 73-year-old man with moderately severe shoulder pain of 6 months' duration. The pain resolved suddenly and completely with root canal in a premolar tooth ipsilateral to the shoulder, and the patient has remained pain-free over the ensuing 6 months.

Bacterial colonization associated with fixed orthodontic appliances. A scanning electron microscopy study

This investigation was undertaken to assess bacterial plaque accumulation adjacent to orthodontic brackets. Experiments were carried out on 11 subjects who were scheduled for orthodontic treatment including extraction of two or four premolars. Metal brackets were bonded to the premolars to be extracted using macro-filled bonding composite. A conventional elastomeric ring was placed around one bracket and a steel ligature wire around the bracket on the contralateral tooth. The subjects were told to continue their normal oral hygiene regimen. Teeth were extracted at 1, 2, or 3 weeks after bracket bonding. Scanning electron microscopic (SEM) examination of brackets, excess composite, and buccal enamel revealed that mature plaque was present on excess composite at 2 and 3 weeks after bonding, whereas plaque on the gingival enamel surface was still at an early stage of development. The results demonstrate that excess composite around the bracket base is the critical site for plaque accumulation due to its rough surface and the presence of a distinct gap at the composite-enamel interface. The method of ligation does not appear to influence the bacterial morphotypes on both composite and enamel surfaces.

Determination of the in situ bactericidal activity of an essential oil mouthrinse using a vital stain method

BACKGROUND

Recent research has indicated that bacteria within a biofilm may undergo changes in susceptibility to antimicrobial agents when compared to planktonic forms. This study was conducted to determine the bactericidal effect of an essential oil-containing mouthrinse (Listerine Antiseptic) on dental plaque bacteria in situ.

METHODS

1-day-old plaque in 17 subjects was sampled at baseline from the buccal surfaces of diagonally contralateral maxillary and mandibular bicuspids and 1st molars. Subjects were then randomly assigned either an essential oil mouthrinse or a sterile saline negative control and rinsed under supervision with 20 ml for 30 s. 30 min later, plaque was sampled from the remaining contralateral posterior teeth. Subjects repeated these procedures with their respective alternate rinse after 1 week. Pooled plaque samples from each subject at each sampling period were stained with a commercially-available fluorescent stain which fluoresces live and dead bacteria green and red, respectively. The stained plaque specimens were analyzed using computerized image analysis. A separate in vitro study was conducted to determine the relationship between the % red stain per sample and bacterial viability.

RESULTS

Analysis of vital stained plaque specimens indicated that following rinsing with the essential oil mouthrinse, 78.7% of bacteria were dead compared to 27.9% following rinsing with the negative control (p<0.001). The in vitro findings demonstrated that the % red stain per sample is reflective of actual bacterial kill.

CONCLUSIONS

This study confirms the findings of previous in vitro and in vivo studies which demonstrated the essential oil mouthrinse to have significant biocidal activity against oral micro-organisms. These studies all support the primacy of a bactericidal mechanism in producing the plaque and gingivitis reductions observed in numerous clinical trials conducted on the essential oil mouthrinse.

Associations amongst three feline Porphyromonas species from the gingival margin of cats during periodontal health and disease

Digoxigenin labelled whole chromosomal DNA probes directed against three feline members of the genus Porphyromonas (P. gingivalis VPB 3492, P. circumdentaria NCTC 12469T and P. salivosa VPB 3313) were used to identify and quantify organisms in samples taken from the gingival margins of 40 domestic cats with different grades of periodontal disease. At the right upper canine tooth, the grade of periodontal disease ranged from 0 to 5 and the cfu of facultative/obligate anaerobes ranged from 5.5 x 10(4) to 2.0 x 10(6)). In 38 of the 40 cats, at least one of the three Porphyromonas species was isolated and regression analysis showed that the cfu of total Porphyromonas sp. was a highly significant indicator of the grade of periodontal disease (p < 0.001, R2 0.510). Feline P. gingivalis was isolated from 37 of the 40 cats and regression analysis showed that it was a highly significant predictor of the grade of periodontal disease (p < 0.001, R2 0.561). The cfu of P. salivosa was a significant predictor of the grade of periodontal disease (p < 0.001, R2 0.286) and regression analysis showed that there was a significant positive relationship between cfu of P. circumdentaria and grade of periodontal disease (p = 0.018, R2 0.116). The periodontal grades at the right upper third premolar tooth ranged from 0 to 6. The cfu of facultative/obligate anaerobes isolated ranged from 1.2 x 10(5) to 7.9 x 10(6), and regression analysis showed that cfu was a significant predictor of periodontal grade (p < 0.001, R2 0.378). The cfu of total Porphyromonas species ranged from 1.2 x 10(4) to 1.7 x 10(6) and regression analysis of the cfu against the grade of periodontal disease showed a highly significant association (p < 0.001, R2 0.633). The cfu of P. gingivalis ranged from 0 to 1.1 x 10(6) and regression analysis of the cfu of P. gingivalis against the grade of periodontal disease showed a highly significant association (p < 0.001, R2 0.439). The cfu of P. salivosa was a significant predictor of the grade of periodontal disease (p < 0.001, R2 0.479) and the same association was found between cfu of P. circumdentaria and grade of periodontal disease (p = 0.002, R2 0.204). This study has established Porphyromonas as anumerically significant and highly prevalent genus in feline periodontal disease.

Dental histology: study of aging processes in root dentine

The amount of sclerotic root dentine increases with age, proceeding from the apex towards the crown. There are obvious optical changes in the tissue, which becomes translucent (dentine is normally opaque). Therefore, the sclerosis of root dentine could be a reliable indicator of age in anthropological studies of human remains. We studied the histological aspects of sclerotic dentine in longitudinal thin sections (70-140 microns) of undecalcified premolars, cut in the bucco-lingual plane. To quantify the sclerosis and to construct a reference standard, we sectioned 85 premolars from subjects of known age (70 from odontological extractions and 15 from a university collection). Another 10 teeth from medieval subjects were studied to assess the applicability of the method to ancient skeletal collections. The technique consists of embedding the tooth in a polyester resin (cold method), sectioning it with a diamond blade microtome. Qualitative analysis was performed with polarized light microscopy and measurements were made with a quote 2D x,y viewer and on digital images. The sclerotic root dentine was quantified with both linear and surface area parameters in order to assess the correlation with age. The quality of the sections was sufficient for the clear discernment and quantification of the sclerotic dentine. Indeed, the technique allowed us to obtain good results with a considerable saving of time and money compared with other dental histological techniques. The best correlation with age was obtained from the surface area parameter, particularly after exclusion of the cementum and pulp chamber. To produce comparable data from similar studies, we advise the use of cold resins, as used here, and digital computerized analyzers because of their accuracy, precision and quickness. The qualitative analysis of the ancient teeth indications that this dental aging techniques can be applied to both recent and ancient dental tissues.

Nd:YAG laser irradiation of infected root canals in combination with microbiological examinations

In this in vivo study, 30 subjects with infected root canals were treated with the neodymium: yttrium-aluminum-garnet, or Nd:YAG, laser using standard laser settings and procedures. In microbiological examinations conducted before irradiation, the authors found streptococci in 30 cases and staphylococci in 15 cases. After the first irradiation, the authors found that 19 root canals showed minimal streptococcal growth and 10 root canals showed minimal staphylococcal growth.

Variations in the predominant cultivable microflora of dental plaque at defined subsites on approximal tooth surfaces in children

The distribution and composition of the resident microflora were determined in approximal gingival margin plaque from 21 premolars extracted from schoolchildren (mean age 12.0 +/- 1.8 yr). Indigo carmine (5% w v) was used to visualize plaque to facilitate sampling. About 1 mm2 of plaque was removed from sites away from (A), to the side of (S), and below (B) the contact area. Plaque samples were dispersed, serially diluted, and cultured on selective and non-selective agar media. An average of seven to nine species was found at each subsite. Streptococcus and Actinomyces were subdivided on the basis of a range of biochemical tests. The predominant Actinomyces and streptococcal species at most subsites were A. naeslundii and Strep. mitis biovar I. A. naeslundii and A. odontolyticus were isolated more often at subsite B (90.5 and 57.1%, respectively), and A. israelii at subsite S (66.7%) Strep. mitis 1 and Strep. sanguis were found more frequently at subsite S (76.2 and 66.7% respectively), whereas Strep mutans, Strep. sobrinus, Strep. gordonii and Veillonella spp. were recovered most commonly from subsite B (85.7, 33.3, 38.1 and 76.2%, respectively). The isolation frequencies of Strep. mutans and Strep. sobrinus were significantly higher at subsite B (A B p < 0.01 and p < 0.05, respectively). Veillonella spp. were significantly higher at subsites B and S (A < B, p > 0.01; B > S, p < 0.05), while Neisseria spp. were most common at subsite A (A > B. p > 0.03). IgAl protease-producing species were found at each subsite, but they formed only a small proportion of the total Streptococcus population. This study has shown that local variations were evident at different subsites, both with respect to species prevalence and to proportions of each species within each subsite. The population shifts in gingival margin plaque appear to relate to the location of plaque in relation to the most caries-prone site below the contact area B.

Sucrose retention and colonization by mutans streptococci at different sites of the dentition

The correlations between the retention and elimination of sucrose at different oral sites and the colonization by mutans streptococci at the same sites were tested in 10 subjects with > 10(5) mutans streptococci per millilitre of saliva. Paraffin-stimulated saliva was collected and plaque samples were taken with a toothpick from all the buccal surfaces except the third molars. One week after the plaque sampling, the sucrose clearance was determined. After a mouth rinse with 10 ml of a 10% sucrose solution, pre-weighed filter paper discs were placed at representative buccal sites of the interdental papilla between molars, premolars and incisors in the upper and lower jaw. The samples were collected 0.5, 2.5, 5.5, 8.5 and 12.5 min after rinsing. Analysis of the sucrose concentration was made using an enzymatic method. The oral sugar clearance was slower in the anterior region of the upper jaw than in the posterior regions and in the central region of the lower jaw. The frequency of mutans streptococci decreased towards the anterior teeth, with Streptococcus sobrinus predominating over Streptococcus mutans. A negative correlation was observed in the upper jaw between sugar clearance and retention and the prevalence of mutans streptococci, whereas the opposite tendency was observed in the lower jaw.

Effect of chlorhexidine treatment followed by stannous fluoride gel application on mutans streptococci in margins of restorations

The effect of antimicrobial treatment on the numbers of mutans streptococci (MS) in plaque from margins of restorations and in saliva was studied. Nineteen persons with well-restored dentitions and > 0.5 x 10(6) MS per ml saliva were treated with 1% chlorhexidine (CHX) gel in individually designed applicators 5 min/day for 9 days. Ten of the subjects continued the treatment with 0.4% stannous fluoride (SnF2) gel and the remaining 9 with a placebo gel for another 14 days. Plaque samples from margins of selected restorations and stimulated saliva were collected at baseline, after the completion of each gel treatment and then again at regular intervals up to 24 weeks. The CHX gel treatment suppressed MS in the margins of restorations as well as in saliva. Additional treatment with the SnF2 gel prolonged this suppression compared with CHX treatment alone. In the CHX-SnF2 group, the number of MS in margins of amalgam and composite restorations was still significantly lower at the end of the study compared with the baseline. In the CHX placebo group, the margins of amalgam restorations, mainly placed in premolars and molars, were recolonized somewhat faster than the margins of composite restorations in the front teeth.

Distribution of Streptococcus mutans and Streptococcus sobrinus at sub-sites in human approximal dental plaque

The distribution and prevalence of Streptococcus mutans and Streptococcus sobrinus were determined at three sub-sites in human approximal plaque: away from (A), to the side of (S) and below (B) the contact area. Small plaque samples were taken from all three sub-sites on clinically sound approximal surfaces of a single premolar from each of 21 schoolchildren. S. mutans was detected significantly more often and in higher proportions than S. sobrinus from sub-sites A (p = 0.019), S (p = 0.034) and B (p = 0.004). S. mutans was detected in highest proportions from the B site compared to the A site (p = 0.025); there were no significant differences in the isolation frequency or prevalence of S. sobrinus from any of the sub-sites. S. mutans and S. sobrinus were never isolated together from the A sub-sites and were recovered together most commonly from the B sub-sites (p < 0.01). It is concluded that S. mutans and S. sobrinus preferentially colonise the most caries-prone site apical to the contact area.

A laboratory microcosm (artificial mouth) for the culture and continuous pH measurement of oral bacteria on surfaces

A laboratory microcosm has been designed for the cultivation of bacteria on surfaces subjected to an adjustable supply of fluids. Bacteria are grown as a microbial film on halved premolar teeth, mounted back to back. Synthetic saliva is dropped slowly over the teeth throughout experiments. A nutrient supplement is provided at regular intervals. The drops of fluid retained by the teeth can be sampled for metabolic end-products. Alternatively, a miniature glass electrode may be set into one half of a tooth assembly to monitor the pH continuously at the stagnation site between tooth segments. Up to six replicate culture flasks and six electrodes can be accommodated in a single experiment. Satisfactory electrode performance was maintained during 66 h experiments. In initial 48 h experiments, teeth were inoculated with Streptococcus rattus BHT or 'Streptococcus mitior' LPA-1 in pure culture and provided with 1% (w/v) glucose for 1 h every 6 h. Bacteria produced typical responses to glucose feeds leading to the formation of 'Stephan'-like curves of pH-fall. Under these conditions, 'Strep. mitior' was more acidogenic than Strep. rattus and the pattern of acid production was distinct for each organism.

Light- and electron-microscopic study of the microbial deposits present on the tongue and dentition of macropods

The dental deposits in the kangaroos and wallabies were similar to human calculus with lysed bacterial cell remnants embedded in previously mineralized areas. The surface of the microbial deposits in contact with the enamel showed: (a) triangular structures 3-5 micron deep and 4-5 micron wide at their base repeating every 4 or 5 micron which probably occupied the remnants of Tomes processes which in macropods do not flatten out; (b) irregular, short (1 micron) projections that probably occupied the inter-prismatic areas. Few organisms were observed on the anterior or dorsal surfaces of the tongues but on the posterior region there was abundant microbial colonization. Large amounts of extracellular matrix were preserved using a fixation technique designed to minimize the loss of water-soluble material. Bacteria were arranged perpendicular to the epithelial cell surfaces and were present on either surface of desquamating epithelial cells. Aqueous fixation erroneously suggested that inter-bacterial and bacterial-epithelial cell adhesion was primarily by fine fibrillar strands.

The predominant cultivable dental plaque flora of beagle dogs with periodontitis

The predominant cultivable dental plaque flora was studied in 10 adult female beagle dogs with advanced periodontitis. Supragingival and subgingival plaque from a maxillary third premolar (P3) was removed and cultured anaerobically on various growth media and all colonies were subcultured and partially characterized. Histopathological specimens of the plaque sampling sites showed significant loss of connective tissue attachment. Spirochetes were found in all samples. Anaerobic gram-negative organisms were predominant in both types of plaque accounting for about 55% of the cultivable organisms in the supragingival plaque and almost 75% in the subgingival plaque. Bacteroides asaccharolyticus was the most predominant organism in the supragingival plaque, whereas Fusobacterium nucleatum predominated in the subgingival flora. Streptococcal and actinomycotic species were common in the supragingival plaque, but their proportions, especially those of the actinomycetes, were decreased in the subgingival flora. In many respects the bacterial profile associated with disease resembled that reported in human periodontal disease.

Isolation of anaerobic bacteria from the root canal systems of necrotic teeth by the use of a transport solution

The purpose of this study was to develop a clinically practical technique for isolating predominant anaerobic microorganisms from the root canal systems of intact necrotic teeth. Fifty-five consecutive teeth, all of which were necrotic, were sampled for this study. The technique developed involved a transport solution into which each sample was placed. At least one anaerobic bacterium was isolated from each case, with as many as four anaerobic bacteria being isolated from one case. Over half of the total number of organisms isolated were anaerobes, and almost half of these organisms were gram-negative. Whereas this technique has enabled the author to isolate and identify the same spectrum of predominant anaerobic bacteria as has been reported recently by others using the rigid VPI technique, the author suggests that the technique described here be utilized when the VPI technique cannot be performed.

Early formation of dental plaque on platic films. 1. Light microscopic observations

In human subjects with healthy gingiva thin transparent plastic films were applied to the buccal surfaces of premolars in the upper and lower jaws. The films were left in place for peiods of 15, 30, 60, 120 and 240 minutes. The presence of coccoid bacteria, leukocytes and epithelial cells was investigated in an area adjacent to the gingival margin. The results showed that by 15 minutes coccoid bacteria had become attached to the artificial tooth surface. The number of microorganisms gradually increased during the time of the study. Large numbers of cocci and the formation of micro-colonies were observed after 120 and 240 minutes. Increasing numbers of leukocytes and epithelial cells were also found during the period of observation.

Composition of dental plaque obtained from eight sites in the mouth of a ten-year-old girl

A study was made of the dental plaque obtained from the proximal surfaces of two premolars from a 10-year-old girl. Four sites were examined on each tooth. There were differences in the proportions of various microorganisms in both the plaque flora inhabiting different sites around the individual teeth, and the flora of the two teeth.

Interdental localization of Streptococcus mutans as related to dental caries experience

The consistency of colonization of tooth surfaces by Streptococcus mutans was studied by sampling four approximal molar surfaces of 9- to 13-year-old children at weekly intervals. It was found that surfaces which harbored detectable levels of the organism tended to be consistently positive, whereas surfaces which were free of detectable levels of the organism also tended to remain that way. Of the total surfaces studied, 81.7% were either consistently positive or consistently negative throughout five consecutive weekly samplings. These data indicate that S. mutans does not uniformly colonize the surfaces of teeth. The consistent localized patterns of colonization observed suggest that S. mutans is not readily transmitted from one tooth surface to another within the mouth. Scanning electron microscope observations revealed that S. mutans colonized the teeth of monoinfected gnotobiotic rats as discrete localized colonies, whereas strains of Actinomyces naeslundii colonized in a more generalized manner. Efforts to sterilize tooth surfaces by application of iodine solution indicated that the populations of S. mutans on some surfaces could be affected for at least 11 to 13 weeks after treatment. The number of tooth surfaces colonized by detectable proportions of S. mutans was found to be far lower in a group of 18 children from Charlotte, N.C., with a low past caries experience than in 20 children from Danvers, Mass., with a high caries experience. The number of tooth surfaces infected with S. mutans therefore strongly paralleled the caries experience of these populations.

Clinical significance of microorganisms and organic films on human enamel

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