Biomedical subjects
J B Kieser
Publications and source records attributed to J B Kieser.
The bactericidal effects of dental ultrasound on Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis. An in vitro investigation.
This study investigated the possible bactericidal acoustic effects of the dental ultrasonic scaler. Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis suspensions, were subjected to the vibrations of a Cavitron P1 insert for 2.5 and 5.0 min in an acoustically-simulated pocket model and the survivors enumerated. The extent of any cavitation occurring within the pocket model to which the statistically significant bactericidal activity observed might be attributed, was determined by 'sonoluminescence', which was then investigated by photomultiplication techniques. However, these failed to detect any sonoluminescence within the pocket space and, moreover, the necessary deflection of the water coolant away from the insert tip, to avoid flooding of the experimental pocket, proved to result in temperatures of 47.6 degrees C and 52.3 degrees C at the respective time intervals, and thereby constituted an alternative possible bactericidal mechanism. Examination of the effects of such temperature changes on the target bacteria then revealed statistically significant differences in the viable counts of both microorganisms after 5.0-min periods, and as such were comparable to those previously detected in relation to the pocket model. Whilst it must be presumed that the bacteriolytic effect observed in the main investigation was due to the incidental temperature changes, in the absence of acoustic cavitation the influence of any associated acoustic microstreaming cannot be discounted. Further investigations to assess the bactericidal potential of acoustic phenomena using a modified experimental to exclude any hyperthermic effects are therefore necessary.
Prevalence of Treponema denticola and Porphyromonas gingivalis in plaque from periodontally-healthy and periodontally-diseased sites.
Intracrevicular plaque from periodontally-healthy individuals who had refrained from oral hygiene measures for 24 h prior to sampling, and subgingival plaque from diseased sites of patients with chronic periodontitis were screened by ELISA for the presence of Porphyromonas gingivalis and Treponema denticola. The samples were also subjected to the PerioScan test to detect the presence of enzymes capable of degrading N-benzoyl-DL-arginine-2-naphthylamide (BANA). Of the 141 samples from periodontally-healthy sites, 73% contained T. denticola antigens and 78% P. gingivalis antigens, compared to 43% and 59%, respectively, in plaque samples from the 159 diseased sites. A positive reaction in the PerioScan test was obtained in 89% of plaque samples from diseased sites and in 60% of those from healthy sites. The correlation between the results of the two assays was poor in the case of intracrevicular plaque from healthy sites. However, with plaque samples from diseased sites, the results of the PerioScan test showed very strong correlation with those obtained with the ELISA, suggesting that the former may be a useful, rapid means of indicating the presence of T. denticola and P. gingivalis in such plaque samples.
The periodontally-involved root surface.
Recent years have seen much research on the periodontally-involved root surface. Many of these studies have produced results which suggest that plaque contaminants of the root surface are only superficially placed, and capable of being removed by gentle means. Further research has attested to the difficulties in rendering periodontally-involved root surfaces free of calculus deposits by instrumentation, yet clinical studies show that periodontal disease can be managed by root planing. It is concluded that root surface debridement is best assessed on the basis of the healing response and that it should aim to disrupt plaque on and remove plaque from the periodontally-involved root surface rather than to remove part of the root surface itself.
Periodontics: a practical approach.
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Assessment of ultrasonic debridement of calculus-associated periodontally-involved root surfaces by the limulus amoebocyte lysate assay. An in vitro study.
This investigation assessed the effectiveness of an in vitro ultrasonic debridement regime on periodontally involved teeth with visually-detectable calculus deposits, using the LAL assay for lipopolysaccharides (LPS) as a marker of bacterial products. 34 single rooted teeth with extensive amounts of calcified accretions were selected, of which 10 served as uninstrumented controls for the estimation of existing LPS levels. The periodontally involved roots of the 24 experimental teeth were debrided with a Cavitron TF-10 tip for a limited time using light pressure and overlapping strokes which ensured complete surface instrumentation without reference to the presence of calculus. Marked reductions in root surface area coverage by calculus were nevertheless achieved as assessed planimetrically from photographic records of the teeth before and after debridement. The root surfaces of each tooth were then stripped away and the harvested material subjected to 'Westphal' extraction and LAL assay for LPS. The resulting LPS yields from the experimental teeth ranged from less than 0.08 to 22.387 ng compared to 1,900 to 29,200 ng from the uninstrumented controls. The extremely small residual LPS yields from the experimental teeth not only confirm the efficacy of ultrasonic debridement but, when coupled with the lack of a relationship with the widely varying amounts of the remaining calculus, support the contention that bacterial plaque rather than calculus has the greater pathogenic potential. These results reinforce the growing impression of the superficial location of bacterial toxic products associated with periodontally involved root surfaces.
A model for teaching periodontal surgery.
A simple laboratory-made model is described for periodontal surgical technique exercises. It has proved useful for tutor demonstration and student practice of all aspects of flap management.
The assessment of ultrasonic root surface debridement by determination of residual endotoxin levels.
Recent demonstrations of the superficial nature and ease of removal of root-surface-associated cytotoxic materials suggest that extensive root-surface instrumentation is not warranted clinically. This in vitro investigation determined the detoxifying effects of a conservative regime of ultrasonic root debridement, using the Limulus amoebocyte lysate assay for lipopolysaccharide (LPS) as an indication of the presence or absence of cytotoxic materials. 20 extracted periodontally-involved single-rooted teeth, with no clinically detectable calculus deposits, were debrided with a Cavitron TF-10 tip. Light pressure, resulting from a force application of approximately 50 g, lasting for 0.8 s/mm2 of root surface was used and complete overlapping instrumentation ensured. The finding of LPS levels of less than 2.5 ng per root in 19 out of 20 teeth after such debridement was comparable to LPS levels found on healthy, uninvolved control teeth, and thus endorses the growing belief that root surface cleanliness can be readily achieved.
Root surface debridement--an in vitro assessment.
Root planing has been advocated to render periodontally involved root surfaces 'biologically compatible' with the surrounding soft tissues and thus promote healing. However, recent work has shown that only small amounts of cytotoxic material are likely to be incorporated within the root surfaces, thereby questioning the rationale for the traditional emphasis that is placed upon the removal of 'diseased cementum'. This investigation assessed by limulus amoebocyte lysate (LAL) assay and Polymyxin B affinity chromatography the extent of residual lipopolysaccharide (LPS) following root surface instrumentation in vitro. A conservative regime was carried out, consisting of 15 instrument strokes per surface designed to ensure complete overlapping of the strokes. This harvested varying amounts of LPS from 18 single-rooted teeth while leaving behind less than 0.24 ng of LPS per tooth in the majority (72%) of cases. This finding endorses the growing belief that extensive root planing may not be warranted.
Lipopolysaccharide (endotoxin) from individual periodontally involved teeth.
The amount of lipopolysaccharide (LPS) in the root surface-associated material from individual periodontally-involved teeth has been determined. LPS was found in the surface material from all of the teeth and the amount present ranged from 19-394 ng/tooth. No significant correlation was found between the amount of LPS extracted from a particular tooth and the mean pocket depth associated with the tooth. However, a weak correlation (rs = +0.461, 0.05 greater than p greater than 0.01) was found between the amount of LPS and the % loss of attachment.
Identity of limulus amoebocyte lysate-active root surface materials from periodontally involved teeth.
A new approach has been developed to circumvent the problems of false positive reactions in the Limulus Amoebocyte Lysate (LAL) assay for lipopolysaccharide (LPS) in root surface materials. These LAL-reactive materials include thrombin, thromboplastin, ribonuclease, ribonucleic acid, lipoteichoic acid and peptidoglycan fragments. In the present study, hot phenol/water extraction of these substances followed by ultracentrifugation of the resulting aqueous phases reduced their concentrations to very low levels. Furthermore, the application of Polymyxin B/Sepharose 4B affinity chromatography to these extracts enabled their intrinsic LAL-activity to be determined. Use of these techniques to assay root surface materials has identified LPS as being the major LAL-reactive material present. The mean LPS yield for the periodontally involved teeth was 4.13 micrograms/tooth, representing 2.82 micrograms/root. In contrast, the mean yield of LPS for the periodontally uninvolved teeth was 3.12 ng/tooth.
The distribution of bacterial lipopolysaccharide (endotoxin) in relation to periodontally involved root surfaces.
The distribution of lipopolysaccharide (LPS) in periodontally involved root surface associated materials has been investigated using improved methods of identification and quantification. 39% of the LPS could be removed by gently washing in water for 1 min and 60% by brushing for 1 min with a slowly rotating bristle brush. The finding that 99% of the LPS can be removed by comparatively gentle procedures suggests that effective root surface debridement may be achieved by methods other than traditional hand instrumentation.
A conservative approach to the management of gingival recession and other gingival 'inadequacy'.
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Assessment of plaque by image analysis.
The uneven distribution and pattern of staining, revealed on root-planed, periodontally-involved root surfaces by the application of a plaque-disclosing solution, precludes the use of conventional plaque scoring indices or other methods of assessment based on planimetric and gravimetric techniques. A method has been developed and evaluated to quantify stained areas using image analysis. The method is reproducible, with an error factor of 1.32%, and represents a comparatively simple, yet effective technique for quantifying plaque on irregular root surface areas.
The removal of root surface deposits.
The importance of adequate root surface instrumentation has received increasing emphasis. The purpose of this study was to determine the extent to which root planning could produce surfaces free of stainable deposits. Initial laboratory investigations on extracted, periodontally involved roots demonstrated that after meticulous root preparation, totally non-stainable surfaces could be obtained. These surfaces were shown to consist of either thin cementum or dentine. The efficacy of instrumenting periodontally involved buccal root surfaces on the anterior teeth of 33 patients, undergoing routine periodontal flap surgery was then evaluated. Root surfaces were instrumented either before or after the reflection of surgical flaps. Remaining bacterial deposits were disclosed with a gentian violet solution and the root surfaces then photographed. Further root planing, disclosure and photography were then carried out. These photographic slides were analysed for stainable deposits on the root surfaces using an image analysis system, based on densitometric principles, to measure the areas of stainable root surface deposits. The findings revealed that root planning under direct vision at the time of surgery was more effective than blind instrumentation. However, in no instance was any root surface found to be completely free of stainable deposits.
Histological assessment of periodontally involved cementum.
Contamination of periodontally involved cementum by bacterial substances such as lipopolysaccharide (LPS) is considered a major reason for root planing. The purpose of the present study was to investigate the presence and location of lipid and polysaccharide within involved cementum as compared with uninvolved cementum. Frozen sections were prepared from the decalcified roots of 36 periodontally diseased and two control teeth. Serial sections were stained for either lipid (Oil-Red-O) or polysaccharide (Alcian Blue - PAS) and also with haematoxylin & eosin (H & E) or Huberstone's gram stain. Specimens of involved and uninvolved cementum were then examined under the light microscope for assessment of differences. Involved cementum from 12 of the periodontally diseased teeth exhibited strongly PAS-positive stained processes penetrating 3-7 mum into the surface of cementum from overlying plaque. Such processes were not observed in uninvolved cementum, suggesting a possible bacterial origin. Lipid granules were noted in only one involved specimen where they were situated up to 10 mum beneath the cemental surface. Similar granules were observed within plaque deposits but never in uninvolved cementum, again suggesting a possible bacterial origin. H & E and gram-stained specimens revealed the presence of microbial deposits in surface defects and within defects at the cemento-dentinal junction (CDJ), as well as penetration of micro-organisms into cementum in the absence of any surface defects. The results indicate that although lipid and polysaccharide of possible bacterial origin may be present within the 10 mum surface zone of involved cementum, the finding of microbial deposits down to the level of the CDJ suggests that all periodontally involved cementum should be removed during root planing, in order to achieve a root surface free of bacterial contamination.
Bacterial endotoxin: a role in chronic inflammatory periodontal disease?
A review of current information was undertaken examining suggested roles for bacterial endotoxin in periodontal disease. Evidence for the presence of endotoxin in plaque, gingival crevicular fluid and periodontally involved cementum is discussed. The biological effects of endotoxin are numerous, and its abilities to induce tissue inflammation, resorb rat foetal bone, activate the complement pathway, stimulate macrophages and activate immune responses are examined in relation to the suggestion that endotoxin is an important factor in the pathogenesis of periodontal disease.
Cementum involved in periodontal disease: a review of its features and clinical management.
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