The significance of prior mechanical therapy for changes of periodontal status achieved by local delivery of a doxycyclinehyclate containing gel.

AIM: The purpose of this retrospective analysis was to examine what effect, if any, the time elapsed between an individual's last episode of scaling and root planing and subsequent treatment with a sustained-release doxycycline hyclate gel (DH) alone or scaling and root planing alone (SRP) would have upon adult periodontitis. METHODS: A total of 207 subjects were included in the DH group and 210 patients in the SRP group. Periodontitis was defined as those sites which presented with pocket depths > or =5 mm and exhibited bleeding upon probing. In both DH and SRP groups, 3 sub-groups of subjects were identified according to their last episode of scaling and root planing prior to the study baseline: within 2 to 6 months, >6 but < or =12 months, and one or more times in their life but not within the last 12 months. Each study site was treated twice over a 9-month study period, once at baseline and again at 4 months. Data from the study sites at 4, 6, and 9 months were then evaluated for changes in probing depth, clinical attachment level, and bleeding upon probing. RESULTS: At the 9-month evaluation, all sub-groups in the DH and SRP treatment arms presented with improvement in the measured clinical parameters, as compared to baseline. No significant differences were observed in the measured periodontal indices among the study sites between the three sub-groups for either treatment. CONCLUSIONS: It is concluded that the time interval since the last episode of scaling and root planing had no observable effect on the results achieved when treating periodontitis sites with locally delivered doxycycline hyclate alone or scaling and root planing alone. The treatment of periodontitis sites with locally delivered doxycycline hyclate resulted in clinical improvement comparable to scaling and root planing irrespective of the patient's prophylaxis frequency.

Controlling biofilm and microbial contamination in dental unit waterlines.

Despite the fact that the ADA had set the goal of less than 200 colony-forming units per milliliter of unfiltered output water from dental unit waterlines to be achieved voluntarily by the year 2000, there is much confusion and resistance within the profession with regard to waterlines. Many in the profession are still wondering what the most effective means are to predictably achieve the goal. It is a well-established fact that bacterial biofilm can readily form within dental unit waterlines and degrade the microbial quality of the water in dental units regardless of the water source. These biofilms are primarily formed by various microcolonies of bacteria that attach to surfaces over time within the waterlines. An increasing number of medically compromised and immunocompromised patients being treated in dental offices and increased public awareness have brought about renewed interest in this issue. There are generally four categories of products that are available to address this issue: independent water systems, sterile water delivery systems, filtration, and chemical treatment protocols. A recent study at the University of California at Los Angeles demonstrates that the Ultra chemical treatment protocol can be an effective means of controlling biofilm in dental unit waterlines.

Soft tissue root coverage as treatment for cervical abrasion and caries.

Root exposure caused by gingival recession may result in cervical abrasion, root caries, root sensitivity, and compromised esthetics. Although cervical root lesions can be treated with Class V restorations, there may be advantages in treating them with soft tissue grafts for root coverage since they restore the dento-gingival unit to its prerecession condition. The rationale for root coverage with soft tissue grafts is reviewed and two cases are presented of successful root coverage procedures in which gingival recession associated with cervical abrasion and caries was present.

The effect of locally delivered controlled-release doxycycline or scaling and root planing on periodontal maintenance patients over 9 months.

BACKGROUND: This research report evaluates clinical changes resulting from local delivery of doxycycline hyclate (DH) or traditional scaling and root planing (SRP) in a group of patients undergoing supportive periodontal therapy (SPT). METHODS: In all, 141 patients received either DH (67) or SRP (74) treatment in sites > or =5 mm on one-half of their dentition at baseline and month 4. RESULTS: Clinical results were determined at month 9. Baseline mean probing depth recordings were similar between the two groups (DH = 5.9 mm; SRP = 5.9 mm). Mean month 9 results showed similar clinical results for attachment level gain (DH 0.7 mm; SRP 0.8 mm) and probing depth reduction (DH 1.3 mm; SRP 1.1 mm). Percentage of sites showing > or =2 mm attachment level gain at month 9 was 24.7% in the DH group and 21.2% in the SRP group. Thirty-nine percent (39%) of DH sites and 38% of SRP sites showed > or =2 mm probing depth reduction. When treated sides of the dentition were compared to untreated sides, DH showed a difference in disease activity (> or =2 mm attachment loss) from 19.3% (untreated) to 7.2% (treated); and SRP from 14.3% (untreated) to 8.1% (treated). CONCLUSIONS: Results show that both DH without concomitant mechanical instrumentation and SRP were equally effective as SPT in this patient group over the 9-month study period.

A controlled re-entry study on the effectiveness of bovine porous bone mineral used in combination with a collagen membrane of porcine origin in the treatment of intrabony defects in humans.

AIM: The purpose of this study was to evaluate the clinical effectiveness of a bovine porous bone mineral used in combination with a porcine derived collagen membrane as a barrier in promoting periodontal regeneration in intrabony defects in humans. MATERIAL AND METHODS: The study employed a split-mouth design. 22 paired intrabony defects were treated and surgically re-entered 6 months after treatment. Experimental sites were grafted with bovine porous bone mineral and received a collagen membrane for guided tissue regeneration. Control sites were treated with an open flap debridement. RESULTS: Preoperative pocket depths, attachment levels and trans-operative bone measurements were similar for control and experimental sites. Post surgical measurements revealed a significantly greater reduction in pocket depth (differences of 1.89 +/- 0.31 mm on buccal 0.88 +/- 0.27 mm on lingual measurements) and more gain in clinical attachment (differences of 1.51 +/- 0.33 mm on buccal and 1.50 +/- 0.35 mm on lingual measurements) in experimental sites. Surgical reentry of the treated defects revealed a significantly greater amount of defect fill in favor of experimental sites (differences of 2.67 +/- 0.91 mm on buccal and 2.54 +/- 0.87 mm on lingual measurements). CONCLUSIONS: The results of this study indicate that clinical resolution of intrabony defects can be achieved using a combination of bovine porous bone mineral and an absorbable, porcine derived collagen membrane when employing a technique based on the principles of guided tissue regeneration. The nature of the attachment between the newly regenerated tissue and the root surfaces needs to be evaluated histologically to confirm the presence of new attachment.

A comparative pilot study of the effects of a dentifrice containing green tea bioflavonoids, sanguinarine or triclosan on oral bacterial biofilm formation.

The aim of the present study was to evaluate the effect of a green tea bioflavonoid/zinc ascorbate-containing dentifrice (Natural Antioxidant Toothpaste) on bacterial plaque biofilm accumulation. Plaque biofilms were formed and observed on saliva-conditioned synthetic hydroxyapatite disks (HA) over 4 days. Two test treatments were performed daily over a 4-day experimental period for a total of 8 treatments. Four test dentifrices were evaluated: a 0.1% bioflavonoid/0.2% zinc ascorbate; a non-active control test dentifrice; a 0.075% sanguinarine/2.0% zinc chloride dentifrice; and a 0.3% triclosan dentifrice. The repeated treatment of the HA with the green tea bioflavonoid/zinc ascorbate, the sanguinarine/zinc chloride, or the triclosan dentifrice resulted in significant reductions in total viable plaque biomass when compared to a non-active placebo control dentifrice.

Two multi-center studies evaluating locally delivered doxycycline hyclate, placebo control, oral hygiene, and scaling and root planing in the treatment of periodontitis.

BACKGROUND: The clinical efficacy and safety of doxycycline hyclate (8.5% w/w) delivered subgingivally in a biodegradable polymer (DH) was compared to placebo control (VC), oral hygiene (OH), and scaling and root planing (SRP) in 2 multi-center studies. METHODS: Each study entered 411 patients who demonstrated moderate to severe periodontitis. Patients had 2 or more quadrants each with a minimum of 4 qualifying pockets > or =5 mm that bled on probing. At least 2 of the pockets were > or =7 mm. Treatment with DH, VC, OH, or SRP was provided at baseline and again at month 4. Clinical parameters were recorded monthly. RESULTS: DH and SRP resulted in nearly identical clinical changes over time in both studies. Mean 9 month clinical attachment level gain (ALG) was 0.8 mm for the DH group and 0.7 mm for the SRP group in Study 1, and 0.8 mm (DH) and 0.9 mm (SRP) in Study 2. Mean probing depth (PD) reduction was 1.1 mm for the DH group and 0.9 mm for the SRP group in Study 1 and 1.3 mm for both groups in Study 2. Frequency distributions showed an ALG > or =2 mm in 29% of DH sites versus 27% of SRP sites in Study 1 and 31% of DH sites versus 34% of SRP sites in Study 2. PD reductions > or =2 mm were seen in 32% of DH sites versus 31% of SRP sites in Study 1 and 41% of DH sites versus 43% of SRP sites in Study 2. Comparisons between DH, VC, and OH treatment groups showed DH treatment to be statistically superior to VC and OH. Safety data demonstrated a benign safety profile with use of the DH product. CONCLUSIONS: Results of this trial demonstrate that treatment of periodontitis with subgingivally delivered doxycycline in a biodegradable polymer is equally effective as scaling and root planing and superior in effect to placebo control and oral hygiene in reducing the clinical signs of adult periodontitis over a 9-month period. This represents positive changes resulting from the use of subgingivally applied doxycycline as scaling and root planing was not limited regarding time of the procedure or use of local anesthesia.

An in vitro assessment and a pilot clinical study of electrical resistance of demineralized enamel.

Electrical resistance measurement was evaluated in vitro and in vivo as a method for comparing the remineralizing performance of toothpastes. In the in vitro study, areas of sound enamel on 12 unrestored, mature, extracted human molars and bicuspids, with electrical resistance readings greater than 99.99 M omega, were demineralized to an electrical resistance of 1 to 4 M omega. The teeth were divided into three groups. The change in electrical resistance was measured following a 15 cycle regimen of treatment, demineralization and salivary soaking. Treatments were five-minute exposures to either a 1:2 slurry in saliva of Enamelon (E), a remineralizing fluoride-toothpaste also containing soluble calcium and phosphate ions, a 1:2 slurry in saliva of Crest (C), a conventional fluoride toothpaste (P), or to saliva alone. Demineralization was performed with a 30-minute exposure to 0.1 M lactic acid 50% saturated with calcium hydroxyapatite. The salivary soaking was 1 hour in duration. The mean electrical resistance of the E, C and the saliva treated sites was 63.9 +/- 4.3, 37.6 +/- 9.5 and 2.1 +/- 0.7 M omega, respectively. The final resistance was statistically different for each group (p < 0.05). A pilot clinical study was then conducted to assess the electrical resistance technology in vivo. Eighteen adult subjects with at least one site of early enamel caries with an electrical resistance between 1.0 M omega and 20.00 M omega were randomly assigned to either Enamelon, Crest, or a non-fluoride placebo toothpaste and asked to brush twice daily. After three months, the mean resistance of the test sites was 23.57 M omega for E, 9.61 M omega for C and 13.24 M omega for P. However, the mean resistance changes did not proceed consistently over time. At the end of the study, the electrical resistance measurements on four sites out of twelve in Group E were suggestive of remineralization, whereas measurements on one site out of ten were suggestive of remineralization in Group C and two or three sites out of twelve were suggestive of remineralization in Group P. Progression of demineralization was possibly indicated in only one site, which was in Group C. There were insufficient subjects for statistical significance in the pilot clinical study. There were apparent problems with the variability of some measurements between visits in the in vivo study. Overall, however, the results of both studies indicate that with modifications to the equipment, electrical resistance measurements may be a means of comparing the remineralization performance of toothpastes.

Disinfection and monitoring of dental unit waterlines.

Recent increased awareness of dental unit waterline contamination has prompted investigations into potential protocols for improvement in the quality of water delivered to patients. When the protocol was followed (n = 12), contamination levels were reduced to below measurable colony forming units (CFU) defined as < 1 CFU/mL within three weeks and maintained thereafter. When adherence to the protocol was not strictly followed after initial disinfection, contamination quickly returned and remained until additional disinfection was performed.

Chemotaxis in Borrelia burgdorferi.

Borrelia burgdorferi is a motile spirochete which has been identified as the causative microorganism in Lyme disease. The physiological functions which govern the motility of this organism have not been elucidated. In this study, we found that motility of B. burgdorferi required an environment similar to interstitial fluid (e.g., pH 7.6 and 0.15 M NaCl). Several methods were used to detect and measure chemotaxis of B. burgdorferi. A number of chemical compounds and mixtures were surveyed for the ability to induce positive and negative chemotaxis of B. burgdorferi. Rabbit serum was found to be an attractant for B. burgdorferi, while ethanol and butanol were found to be repellents. Unlike some free-living spirochetes (e.g., Spirochaeta aurantia), B. burgdorferi did not exhibit any observable chemotaxis to common sugars or amino acids. A method was developed to produce spirochete cells with a self-entangled end. These cells enabled us to study the rotation of a single flagellar bundle in response to chemoattractants or repellents. The study shows that the frequency and duration for pausing of flagella are important for chemotaxis of B. burgdorferi.

The inhibiting effect of aqueous Azadirachta indica (Neem) extract upon bacterial properties influencing in vitro plaque formation.

The purpose of this investigation was to examine the inhibitory effects of aqueous extracts derived from the bark-containing sticks (Neem stick) of Azadirachta indica upon bacterial aggregation, growth, adhesion to hydroxyapatite, and production of insoluble glucan, which may affect in vitro plaque formation. Neem stick extracts were screened for minimal bacterial growth inhibition (MIC) against a panel of streptococci by means of a broth dilution assay. Initial bacterial attachment was quantified by the measurement of the adhesion of 3H-labeled Streptococcus sanguis to saliva-conditioned synthetic hydroxyapatite. The effect of the Neem stick extract upon insoluble glucan synthesis was measured by the uptake of radiolabeled glucose from 14C-sucrose. Aggregating activity of the Neem stick extracts upon a panel of streptococci was also examined. No inhibition of bacterial growth was observed among the streptococcal strains tested in the presence of < or = 320 micrograms/mL of the Neem stick extract. The pre-treatment of S. sanguis with the Neem stick extract or the gallotannin-enriched extract from Melaphis chinensis at 250 micrograms/mL resulted in a significant inhibition of the bacterial adhesion to saliva-conditioned hydroxyapatite. Pre-treatment of saliva-conditioned hydroxyapatite with the Neem stick or gallotannin-rich extract prior to exposure to bacteria yielded significant reductions in bacterial adhesion. The Neem stick extract and the gallotannin-enriched extract from Melaphis chinensis inhibited insoluble glucan synthesis. Incubation of oral streptococci with the Neem stick extract resulted in a microscopically observable bacteria aggregation. These data suggest that Neem stick extract can reduce the ability of some streptococci to colonize tooth surfaces.

The determination of ionic bonding interactions of N-phenyl glycine and N-(2-hydroxy-3-methacryloxypropyl)-N-phenyl glycine as measured by carbon-13 NMR analysis.

The purpose of the present investigation was to determine whether high-resolution carbon-13 nuclear magnetic resonance could be utilized for detection of ionic bonding interactions of NPG and NPG-GMA with selected inorganic cations. The C1-carbonyl carbon of NPG and NPG-GMA were labeled with 13C to help magnify the spectral response signal. The labeled monomers were allowed to react with Ca(OH)2 and LiOH. The C-13 carbonyl resonance was observed by solution- and solid-state NMR. The interaction of the cations in solution and on a powered glass support resulted in a downfield chemical shift of about 2-5 ppm, indicating the presence of a chemical interaction between the monomer and the cations. The reaction of the monomers with the solid substrates of hydroxyapatite, and bovine dentin did not result in a significant downfield shift in the carbonyl resonance. The results provide evidence that high-resolution nuclear magnetic resonance can be used for evaluation of chemical bonding interactions of dental adhesives with inorganic ions.

Detachment of oral bacteria from saliva-coated hydroxyapatite by human polymorphonuclear leukocytes.

Human polymorphonuclear leukocytes (PMN) demonstrated the ability to detach Actinomyces viscosus, A. naeslundii and Streptococcus sanguis from saliva-coated hydroxyapatite beads (SHA). Between 60 to 80% of bacteria were detached within 1 hour at PMN-to-bacteria ratios between 1:10 to 1:22. Detachment was enhanced by treating bacteria with fresh but not heat-inactivated normal human serum. Detachment of serum-treated A. viscosus was inhibited by cytochalasin B, L-1-tosylamide-2-phenylethylchloromethyl ketone (TPCK), and deoxyglucose but not colchicine, phenylmethylsulfonyl fluoride (PMSF), N-carbobenzoxy-L-phenylalanine chloromethyl ketone (ZPCK), and sodium azide. In the absence of serum treatment, the detachment of A. viscosus was insensitive to lactose, galactose, and mannose. We conclude that PMN can efficiently detach bacteria from SHA, this detachment is enhanced by serum, and this enhancement is probably dependent upon complement. Additionally, detachment of A. viscosus bound to SHA by PMN (1) does not appear to involve bacterial lectin activity, (2) seems to be dependent upon glycolytic metabolism, microfilament formation, and the activity of a TPCK-sensitive serine protease, and (3) is not sensitive to inhibitors of tubulin polymerization or heme-protein activity.

A study of in vitro attachment of Streptococcus sanguis and Actinomyces viscosus to saliva-treated titanium.

This study examined the initial attachment of Streptococcus sanguis G9-B and Actinomyces viscosus T14V to saliva-treated powdered enamel and titanium surfaces. Using an in vitro adherence model, significantly lower numbers of Actinomyces viscosus T14V bound to the saliva-treated titanium surface when compared to that of the similarly treated enamel. The binding of Streptococcus sanguis G9-B to titanium or enamel did not vary significantly. A comparison of the percentage of cells bound to the titanium surface revealed that S sanguis cells attached in significantly higher numbers when compared to the A viscosus cells.

Dental professional's role in monitoring and maintenance of tissue-integrated prostheses.

The long-term success of an implant-supported prosthesis is dependent not only on osseointegration of the implant to the surrounding osseous structures, but also the integrity and health of the surrounding peri-implant tissues. This paper defines and discusses the dental professional's role in (1) examining and assessing the peri-implant tissues (2) providing clinical maintenance protocols, and (3) recommending effective home-care instructions for a patient with implant-supported prostheses.

Differential modulation of adherence of oral streptococci by human neutrophil myeloperoxidase.

In this study, the modulation of adherence of hydrogen peroxide (H2O2)-producing and non-H2O2-producing strains of oral streptococci by the host leukocyte enzyme myeloperoxidase (MPO) was examined. It was found that exposure to MPO decreased adherence of many strains of oral streptococci to saliva-coated hydroxyapatite beads in the presence of exogenous H2O2 and chloride. The MPO-H2O2-Cl-system increased the adherence of one strain. In the absence of exogenous H2O2, the MPO-H2O2-Cl-system decreased the adherence of H2O2-producing strains only. Glucose increased streptococcal H2O2 production and also increased the anti-adhesive activity of MPO in the absence of exogenous H2O2. We conclude that: (1) host leukocytes can modulate the adherence of oral streptococci via MPO; (2) endogenous production of H2O2 by the oral streptococci can provide sufficient substrate H2O2 to drive this system; and (3) MPO will exert differential modulatory effects on the adherence of oral streptococci, based in part upon the level of endogenous H2O2 production and in part upon the particular characteristics of the adhesins of the bacteria.

Induction of activated lymphocyte killing by bacteria associated with periodontal disease.

Complex interactions occur among host defense cells during bacterial infection. Bacteria and bacterial products may enhance or inhibit the effector and regulatory activity of human lymphocytes. Accordingly, we tested the ability of human periodontal pathogens to activate peripheral blood lymphocytes using standard chromium-release assays to measure lymphocyte-mediated cytolysis. Human adherent-cell depleted peripheral blood lymphocytes (PBL) with the addition of glutaraldehyde-fixed bacteria at a 5:1 bacteria:lymphocyte ratio were incubated at 37 degrees C for 24 hr in RPMI 1640 medium. Six of eight bacteria tested significantly augmented lymphocyte killing of the natural killer (NK) cell-sensitive human erythroleukemia cell line K562. E. corrodens, representing activating bacteria, was also able to induce the killing of NK-resistant targets (M14, Raji), comparable with induction by interleukin-2. Lipopolysaccharides extracted from A. actinomycetemcomitans strains, when incubated with PBL, were able to enhance cytotoxicity without the presence of whole bacteria. A majority of cytotoxicity was mediated by NK cells bearing Leu-11 and NKH-1 markers.

Osteoporosis and mandibular bone resorption: a prosthodontic perspective.

Previous studies have examined the effects of osteoporosis on the vertebra, femur, and tibia. However, few studies have examined the effects on the mandible by using an animal model to quantify bone resorption. Osteoporosis was induced through pair feedings of a high protein, low calcium diet. Before this induction, experimental and control animals were injected subcutaneously with radioactive tritiated tetracycline. Bone resorption was quantified by measuring the amount of radioactivity present after the test diets were given for 90 days. Standard scintillation techniques were used for extracting the radioactivity from each half mandible. The following conclusions can be made from the results of this investigation: A significant difference in mandibular bone resorption was associated with an osteoporotic inducing diet high in protein and low in calcium. Bone resorption in the experimental group of animals was 17% greater than in the control group. Alkaline phosphatase may be an important indicator of osteoporosis in the Sprague-Dawley rat. Elevated levels were found in those with the osteoporotic diet. The animals in the control and experimental groups consumed similar amounts of their respective diets. No significant difference was found in the weight gains of either group. The histologic picture, although not pathognomonic for osteoporosis, was consistent with many findings in the literature describing osteoporosis. This study has shown that osteoporotic diets may increase the amount of bone resorption in the mandibles of Sprague-Dawley rats.