Clinical and microbiological status of osseointegrated implants

Peri-implantitis, an inflammatory response around implants, has a poorly defined etiology and pathogenesis. To better understand the role of specific microorganisms in this disease process, clinical and microbiological parameters were examined in 24 patients with 98 osseointegrated implants. Sites were evaluated for probing depth (PD), plaque/calculus index (PI), gingival bleeding index (GBI), mobility, and crevicular fluid flow rate (CFFR). Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia in subgingival plaque were identified by latex agglutination assays. Clinically, a statistically significant correlation (P < 0.001) was observed between probing depth and the length of time an implant was present. Mobility was also significantly greater (P < 0.001) in the maxillary than in the mandibular implants. Subgingival sites harboring one of the three microorganisms had significantly greater PD, GBI, and CFFR than non-colonized sites. Implants in partially edentulous patients more frequently were colonized with P. gingivalis/P. intermedia than edentulous patients. The incidence of these microorganisms also correlated with fixture longevity. Implants present for 3 to 4 years had a significantly greater frequency of test microorganisms than implants present for 1 to 2 years. These findings suggest that microbial pathogens associated with periodontitis occur more commonly around implants exhibiting gingival inflammation (GBI) and may contribute to peri-implantitis.     

Subgingival temperature: relation to gingival crevicular fluid enzymes, cytokines, and subgingival plaque micro-organisms

There have been no reports on the relationship of subgingival temperature to specific gingival crevicular fluid (GCF) components. Therefore, the purpose of this cross-sectional study was to determine whether there was any relationship between subgingival temperature and GCF levels of neutrophil elastase (NE), myeloperoxidase (MPO), beta-glucuronidase (BG), interleukin-1 alpha (IL-1), and interferon alpha (IFN). Furthermore, another objective was to confirm an association of subgingival temperature with clinical parameters and specific subgingival plaque micro-organisms as has been reported earlier. 27 human subjects each having healthy (n = 50), gingivitis (n = 59) and periodontitis (n = 53) sites were evaluated. The plaque index (PI), subgingival temperature, probing depth, attachment loss, bleeding index and gingival index were measured. GCF was sampled following the measurement of the PI and removal of the supragingival plaque. GCF samples were assayed for the enzymes NE, BG, MPO and the cytokines IFN-alpha and IL-1 alpha. A sterile Gracey curette was utilized at each sampled site to collect subgingival plaque. The plaque samples were evaluated using an immunoassay. Subgingival temperature was found to directly correlate with all clinical parameters (p < 0.001). Significant, albeit not large, correlations were found between subgingival temperature and NE (r = 0.35, p < 0.001), MPO (r = 0.26, p < 0.001) and BG (r = 0.23, p < 0.01). Temperature was found to correlate positively with E. corrodens (r = 0.33, p < 0.02) and F. nucleatum (r = 0.25, p < 0.05) but not with P. intermedia (r = 0.02, p = 0.9), P. gingivalis (r = 0.20, p = 0.1) and A. actinomycetemcomitans (r = 0.01, p > 0.9). In conclusion, subgingival temperature is correlated with the GCF enzymes, NE, MPO and BG as well as the clinical parameters and specific plaque micro-organisms associated with periodontal disease.     

Modification of cystatin C activity by bacterial proteinases and neutrophil elastase in periodontitis

AIM: To study the interaction between the human cysteine proteinase inhibitor, cystatin C, and proteinases of periodontitis associated bacteria. METHODS: Gingival crevicular fluid samples were collected from discrete periodontitis sites and their cystatin C content was estimated by enzyme linked immunosorbent assay (ELISA). The interaction between cystatin C and proteolytic enzymes from cultured strains of the gingival bacteria Porphyromonas gingivalis, Prevotella intermedia, and Actinobacillus actinomycetemcomitans was studied by measuring inhibition of enzyme activity against peptidyl substrates, by detection of break down patterns of solid phase coupled and soluble cystatin C, and by N-terminal sequence analysis of cystatin C products resulting from the interactions. RESULTS: Gingival crevicular fluid contained cystatin C at a concentration of approximately 15 nM. Cystatin C did not inhibit the principal thiol stimulated proteinase activity of P gingivalis. Instead, strains of P gingivalis and P intermedia, but not A actinomycetemcomitans, released cystatin C modifying proteinases. Extracts of five P gingivalis and five P intermedia strains all hydrolysed bonds in the N-terminal region of cystatin C at physiological pH values. The modified cystatin C resulting from incubation with one P gingivalis strain was isolated and found to lack the eight most N-terminal residues. The affinity of the modified inhibitor for cathepsin B was 20-fold lower (Ki 5 nM) than that of full length cystatin C. A 50 kDa thiol stimulated proteinase, gingipain R, was isolated from P gingivalis and shown to be responsible for the Arg8-bond hydrolysis in cystatin C. The cathepsin B inhibitory activity of cystatin C incubated with gingival crevicular fluid was rapidly abolished after Val10-bond cleavage by elastase from exudate neutrophils, but cleavage at the gingipain specific Arg8-bond was also demonstrated. CONCLUSIONS: The physiological control of cathepsin B activity is impeded in periodontitis, owing to the release of proteinases from infecting P gingivalis and neutrophils, with a contribution to the tissue destruction seen in periodontitis as a probable consequence.     

Metronidazole may inhibit intestinal colonization with Clostridium difficile

OBJECTIVE: To evaluate the clinical and microbiological efficacy of minocycline in a subgingival local delivery system as an adjunct to tooth scaling and root planing in dogs with periodontal disease. ANIMALS: Nine 4- to 7-year-old Beagles with periodontitis. PROCEDURE: After scaling of teeth and root planing, 2 treatment and 1 or 2 control sites were selected for each dog: treated sites (n = 18) received minocycline hydrochloride periodontal formulation and control sites (n = 12) received ointment base (no minocycline). Gingival crevicular fluid was collected at a baseline (prior to treatment) and at week 4. Clinical and microbiological effects were evaluated and compared among sites. RESULTS: In minocycline-treated sites, clinical indices were significantly decreased at week 4, compared with those at baseline. Minocycline-treated sites were associated with a significant decrease in gingival crevicular fluid, probing depth, and bleeding on probing values, compared with those for control sites at week 4. Compared with that for control sites, total bacteria count in periodontal pockets of minocycline-treated sites had an obvious tendency to decrease by week 4. Proportions of Porphyromonas and Fusobacterium spp were significantly decreased at week 4, compared with proportions at control sites and with pretreatment (baseline) values. CONCLUSIONS: When used as an adjunct to tooth scaling and root planing, minocycline periodontal formulation stimulated favorable clinical and antimicrobial responses.     

A relationship between proteinase activity and clinical parameters in the treatment of periodontal disease

The objective of this research was to determine the effectiveness of a biochemical assay which measures proteolytic enzyme activity in gingival crevicular fluid (GCF) and to relate this enzyme activity to clinical parameters traditionally utilized for periodontitis detection. A clinical trial was conducted on 8 periodontitis subjects with > or =4 sites exhibiting a loss of attachment of > or =5 mm and probing depths of > or =5 mm with bleeding on probing. On each subject, a plaque index was performed, followed by GCF sampling at those sites which exhibited a loss of attachment and probing depths. GCF was analyzed for activity against benzoyl-L-arginine-p-nitroanilide in the presence (BAPNA w/gly-gly) and the absence (BAPNA w/o gly-gly) of glycyl-glycine and against MeOSuc-Ala-Ala-Pro-Val-pNA and Suc-Ala-Ala-Pro-Phe-pNA for neutrophil serine proteinases activity (elastase and cathepsin G, respectively). Subsequently, a gingival index was performed, attachment levels and probing depths were recorded using a constant force probe with bleeding on probing being noted. A split-mouth design was employed and half mouths were randomly assigned to the following treatment groups: group A, half of the mouth received scaling/root planing and polishing: group B, half of the mouth received no treatment (control). Subjects were treated, then instructed on toothbrushing and interdental cleaning. After 4 weeks, subjects returned to receive a plaque index; GCF sampling, gingival index, attachment levels, probing depths and bleeding on probing as described above. Using a paired Student t-test, the findings suggest that BAPNA w/gly-gly was significantly less in treatment sites than in non-treated control sites (p=0.05). No such correlation was found for other activities, including neutrophil serine proteinases which were shown to occur in GCF in free, proteolytically active forms. In addition, significant treatment effects were detected for probing depths (p= 0.03) which reduced by 1.3 mm and attachment levels (p=0.02) which gained 0.7 mm. The reduction of P. gingivalis from treated periodontitis sites as detected by a significant decrease in BAPNA w/ gly-gly may prove to be a valuable marker for periodontal disease activity.     

Tricuspid valve endocarditis in a non-drug addict associated with peliosis hepatis

The aims of the present study were to investigate whether the tachykinins substance P and neurokinin A were present in gingival crevicular fluid in both periodontal health and disease and to study the relationship with periodontal inflammation. Gingival crevicular fluid (GCF) was collected from a healthy, a gingivitis and a periodontitis site in 20 subjects with periodontitis and from a healthy site in 20 subjects without periodontitis. The volume of GCF was measured and each sample subsequently analysed for substance P and neurokinin A by radioimmunoassay. There were significantly increased levels of substance P-like immunoreactivity (SP-LI) and neurokinin A-like immunoreactivity (NKA-LI) in gingivitis and periodontitis sites compared with healthy sites. Both tachykinins were significantly elevated in periodontitis affected subjects, with significantly more tachykinin-like immunoreactivity at healthy sites in periodontitis affected compared with periodontally-healthy subjects. Despite the considerable individual variation in the levels of SP-LI and NKA-LI, both tachykinins were present at levels at which they could have biological activity. It is concluded that substance P and neurokinin A may have a r?le in the pathogenesis of periodontal disease and that further investigations could prove useful in clarifying the mechanisms through which neuropeptides could modulate periodontal health and disease.     

Nucleotide excision repair proteins may be involved in the fixation of glyoxal-induced mutagenesis in Escherichia coli

Earlier studies in our laboratories demonstrated that particles of a number of snack foods that are retained on the dentition accumulate fermentable sugars and short-chain carboxylic acids (SCCA; acetic, formic, lactic, and propionic) to different degrees. The present study was undertaken to test the hypothesis that the accumulated SCCA can induce a gingival inflammatory response. Five periodontally and medically healthy subjects were given portions of plain doughnuts (high SCCA levels) or oatmeal cookie (low SCCA), or had the SCCA applied directly to the gingival margins of designated teeth. Subjects were given wax to chew, or nothing, as controls. Inflammation was assessed by measurements of subgingival temperature, flow rates of gingival crevicular fluid (GCF), and neutrophil emigration into GCF. Subgingival temperatures of the maxillary gingiva rose by 1.32 +/- 0.30 degrees C (mean +/- SE) 5 min after the subjects consumed the doughnuts and remained elevated for at least 1 hr. These values were significantly higher than those obtained from subjects after ingestion of oatmeal cookies (0.63 +/- 0.17 degree C; p < 0.01), consistent with the low levels of SCCA in the retained cookie particles. Wax chewing elicited a similar response, indicating a masticatory effect on the gingiva. Gingival temperatures in the unchallenged controls remained unchanged. Neutrophil emigration into the GCF was significantly elevated in subjects after doughnut consumption. Rinses with a solution of SCCA, or application of the SCCA to the gingiva, also brought about significant elevations in subgingival temperature and neutrophil emigration. The findings describe the inflammatory effects of food ingestion on the gingiva of healthy human subjects, and support the hypothesis that SCCA in the particles of retained food are at least partly responsible for the observed responses.     

Salvage treatment with paclitaxel and gemcitabine for patients with non-small-cell lung cancer after cisplatin- or docetaxel-based chemotherapy: a multicenter phase II study

The objective of this study was to investigate the association of the oxygen tension in the periodontal pockets with clinical parameters of gingival inflammation of the maxillary anterior teeth of 32 patients. The pocket oxygen tension (pO2) was measured by a polarographic method with electronic compensation for temperature change. The oxygen saturation of hemoglobin (SO2) in the gingiva was determined with tissue reflectance spectrophotometry. Gingival crevicular fluid flow (GCF) was measured with electronic impedance. No significant association was found between pocket pO2 and the modified gingival index, the plaque index, and GCE Pocket pO2 showed significant correlation with probing depth (r = -0.57, P = 0.0005). Significant correlation was observed between pocket pO2 and gingival SO2 (r = 0.69, P < 0.0001). When all variables were entered into a multiple regression model, only gingival SO2 had a significant independent effect on the pocket pO2 (P = 0.0005). These results indicate that the oxygen sufficiency in the gingiva has a significant independent influence on the pocket oxygen tension. These studies provide the basis for understanding the oxygen tension in the periodontal pocket, which likely is a major determinant of the subgingival microflora. The studies may also lead to the development of methods for diagnosing and monitoring periodontal diseases.     

Maintenance and treatment of the ailing and failing implant

Due to the pathologic nature of oral bacteria, the partially edentulous implant patient is at a greater risk than the fully edentulous. Peri-implantitis and/or retrograde peri-implantitis can result in ultimate loss of the implant fixture. It is important that the implant dentist understand the difference between the ailing implant, the failing implant, and the failed implant. This article discusses the pathologic diseases that affect dental implants and how to treat the "infected" implant (degranulation and detoxification) for titanium and hydroxylapatite-coated implants. Implant maintenance, including hand or motorized brushes, flosses, and oral rinses (chlorhexidine, 0.2%) will also be presented.     

Crevicular fluid level of beta-glucuronidase in relation to clinical periodontal parameters and putative periodontal pathogens in early-onset periodontitis

Analysis of beta-glucuronidase (betaG) in the gingival crevicular fluid (GCF) provides an indication of neutrophil influx into the crevicular environment. The aim of this study was to test the hypotheses that: (1) betaG is significantly elevated in individuals with early-onset periodontitis (EOP) and that betaG activity correlates with disease severity; and (2) betaG level may reflect the local bacterial challenge in the gingival crevice. The study subjects consisted of a sub-sample of individuals examined in the National Survey of Oral Health of United States Children, which was undertaken during the 1986/87 school year. A total of 249 individuals were selected based on presence or absence of clinical attachment loss at baseline. The individuals were examined a second time 6 years later and the clinical attachment loss was assessed, and subgingival plaque and GCF were collected. The subjects were classified into 3 types of EOP and a control group. BetaG activity in the GCF and the levels of 7 putative micro-organisms in the pocket were assessed. The generalized EOP group had the highest betaG activity, followed by the localized and incidental EOP groups, and the controls, respectively. There was a significant increase in betaG activity with the increase in probing depth. Also, sites with bleeding on probing had a significantly higher betaG activity than sites without bleeding. However, the effect of gingival inflammation on betaG activity was more evident in the generalized and localized EOP groups. Sites harboring high levels of one or more of the micro-organisms tended to have high betaG activity. There were moderate differences between the organisms with respect to their effect on betaG activity, but sites with high numbers of Porphyromonas gingivalis, Prevotella intermedia, or Treponema denticola also had the highest betaG activity. The present findings suggest that betaG activity in GCF from patients with EOP can be of value in the early identification of individuals at higher risk of developing EOP The findings also suggest that host mechanisms leading to higher betaG activity in EOP represent systemic responses and are only partly related to the presence of local factors at the site-level.     

Biological factors contributing to failures of osseointegrated oral implants. (I). Success criteria and epidemiology

The aim of this review was to offer a critical evaluation of the literature and to provide the clinician with scientifically-based diagnostic criteria for monitoring the implant condition. The review presents the current opinions on definitions of osseointegration and implant failure. Further, distinctions between failed and failing implants are discussed together with the presently used parameters to assess the implant status. Radiographic examinations together with implant mobility tests seem to be the most reliable parameters in the assessment of the prognosis for osseointegrated implants. On the basis of 73 published articles, the rates of early and late failures of Br?nemark implants, used in various anatomical locations and clinical situations, were analyzed using a metanalytic approach. Biologically related implant failures calculated on a sample of 2,812 implants were relatively rare: 7.7% over a 5-year period (bone graft excluded). The predictability of implant treatment was remarkable, particularly for partially edentulous patients, who showed failure rates about half those of totally edentulous subjects. Our analysis also confirmed (for both early and late failures) the general trend of maxillas, having almost 3 times more implant losses than mandibles, with the exception of the partially edentulous situation which displayed similar failure rates both in upper and lower jaws. Surgical trauma together with anatomical conditions are believed to be the most important etiological factors for early implant losses (3.60% of 16,935 implants). The low prevalence of failures attributable to peri-implantitis found in the literature together with the fact that, in general, partially edentulous patients have less resorbed jaws, speak in favour of jaw volume, bone quality, and overload as the three major determinants for late implant failures in the Br?nemark system. Conversely, the ITI system seemed to be characterized by a higher prevalence of losses due to peri-implantitis. These differences may be attributed to the different implant designs and surface characteristics. On the basis of the published literature, there appears to be a number of scientific issues which are yet not fully understood. Therefore, it is concluded that further clinical follow-up and retrieval studies are required in order to achieve a better understanding of the mechanisms for failure of osseointegrated implants.     

Post-insertion peri-implant tissue assessment: a longitudinal study

The peri-implant gingivae act as a biological barrier that prevents the ingress of plaque bacteria, oral debris, and saliva components into the internal environment of the jaw. The integrity of this barrier around a total of 163 Steri-Oss HA-coated threaded root-form implants placed in 48 patients was examined at six-month intervals over a 42-month time period, beginning at the time of final prosthetic placement. Five clinical parameters for tissue assessment were used: Mean Implant Sulcus Readings (MISR), Mühlemann Sulcus Bleeding Index (SBI), Miller's Mobility Index (MI), bone loss readings (BL), and gingival condition (GI). Bone loss and mobility were negligible throughout the 42-month study period. At six months post-insertion, 58.6% of the Mean Implant Sulcus Readings exceeded 4 mm. Gingival conditions and bleeding response also were non-ideal in a significant number of cases (52.9 and 62.1%, respectively). However, all three of these assessments later showed dramatic improvement. Patients' inability to "deplaque" their newly acquired implant prostheses effectively may be a factor contributing to the high incidence of undesirable pocket depths and non-optimal gingival appearance at the first six-month assessment point. Attainment of the necessary skills may account for the improved readings at the later evaluations.     

Implicit and self-attributed dependency strivings: differential relationships to laboratory and field measures of help seeking

Inflammatory processes occurring in the vicinity of bone tissue often result in stimulation of osteoclast activity and loss of skeletal mass. The aim of the current study was to determine if inflammatory exudates collected from gingival pockets in patients with periodontitis contain factors capable of stimulating resorptive activity. The degree of bone mineral mobilization and bone matrix degradation was assessed by analysis of the release of 45Ca and 3H from bones prelabelled with 45CaCl2 and [3H]proline, respectively. Gingival crevicular washings from six patients with signs of periodontitis stimulated 45Ca or 3H release from the calvarial bones. The stimulatory effect of the gingival crevicular washings on 45Ca release was concentration- and time-dependent, and reduced by calcitonin, a specific osteoclast inhibitor. These data demonstrate that crevicular fluid contains factor(s) which can stimulate osteoclastic degradation of bone in vitro. The bone resorbing activity was partially retained after extensive dialysis. Analysis of the concentrations of prostaglandin E2, interleukin-1alpha and interleukin-1beta in the crevicular fluids, and comparisons of these agents as stimulators of 45Ca release in the mouse calvarial assay, suggest that prostaglandin E2 is not the sole factor responsible for the bone resorbing activity of the exudates. The data indicate that other factors, such as IL-1, may play key roles in the stimulation of osteoclastic activity by gingival crevicular washings.     

Pigment cell research: what directions?

The purpose of this study was to compare the phenotypic distribution of resident gingival mononuclear inflammatory cells from tissues associated with peri-implantitis and periodontitis. Inflamed gingiva was obtained from six patients during surgical removal of failed dental implants. Similarly, inflamed gingiva around teeth was obtained from eight patients with moderate to advanced periodontitis. Monoclonal antibodies were used to identify membrane antigens from CD4+ T-lymphocytes, CD4+/CD8(+)-activated T-lymphocytes, tissue macrophages, CD20+ B-lymphocytes, and MHC class II (Ia) antigens. Gingival inflammation associated with both dental implants and natural teeth was characterized by substantial numbers of CD4+ T-lymphocytes, resident macrophages, and B-lymphocytes. In addition, there was an abundance of HLA class II-positive mononuclear cells throughout most specimens. These results suggest that the gingival mononuclear inflammatory response in peri-implantitis and periodontitis is similar and support the hypothesis that similar inflammatory mechanisms are associated with both conditions.     

Load factor control for implants in the posterior partially edentulous segment

There are inherent biomechanical differences in the implant treatment of completely edentulous arches and posterior partially edentulous segments. The partial prosthesis does not benefit from cross-arch stabilization and is, therefore, more susceptible to bending loads. Because of the difference in mobility between teeth and implants, implants may carry a major share of load when mixed with teeth in the same quadrant. However, the frequency of implant overload in posterior partial restorations is low, and, with appropriate treatment planning, overload in these situations is almost always preventable. A checklist procedure is proposed to help the clinician enumerate and evaluate deleterious load factors. By screening patients for such factors in advance, the clinician may identify and avoid potential overload situations when conceiving and fabricating implant-supported posterior partial prostheses. A second checklist, for use at follow-up appointments, lists alarm factors that serve as an early warning of overload once the prosthesis is in place.     

A comparison of topical ketorolac, systemic flurbiprofen, and placebo for the inhibition of bone loss in adult periodontitis

Systemic non-steroidal anti-inflammatory drugs (NSAIDs) have been shown to reduce alveolar bone loss in periodontitis. This study assesses the efficacy of a topical NSAID rinse, containing ketorolac tromethamine as the active agent. Adult periodontitis patients (n = 55) were studied in this 6-month randomized, double blind, parallel, placebo and positive-controlled study. Each patient had a least 3 sites at high risk for bone loss as assessed by low dose bone scan. Groups, balanced for gender, were assigned to one of three regimens: bid ketorolac rinse (0.1%) with placebo capsule; 50 mg bid flurbiprofen capsule (positive control) with placebo rinse; or bid placebo rinse and capsule. Prophylaxes were provided every 3 months. Monthly examinations assessed safety, gingival condition, and gingival crevicular fluid PGE2. Standardized radiographs were taken at baseline and at 3 and 6 months for digital subtraction radiography. A significant loss in bone height was observed during the study period in the placebo group (-0.63 +/- 0.11; P < 0.001), but not in the flurbiprofen (-0.10 +/- 0.12; P = 0.40) or ketorolac rinse (+0.20 +/- 0.11 mm; P = 0.07) groups. Nested ANOVA revealed that ketorolac and flurbiprofen groups had less bone loss (P < 0.01) and reduced gingival crevicular fluid PGE2 levels (P < 0.03) compared to placebo. ANOVA suggests (P = 0.06) that ketorolac rinse preserved more alveolar bone than systemic flurbiprofen at the dose regimens utilized. These data indicate that ketorolac rinse may be beneficial in the treatment of adult periodontitis.     

Comparison of position repeatability of a human operator and an industrial manipulating robot

STATEMENT OF PROBLEM: Implant-supported restorations in the partially edentulous jaw have been performed at the Mayo Clinic for more than 10 years. Clinical performance of the implants and the prostheses should be reported to ensure effectiveness of this procedure. PURPOSE: This retrospective study described results for implant survival, implant fracture rate, prosthetic complications, and design changes that may impact these results. MATERIAL AND METHODS: A retrospective chart review was conducted of all registered implant patients in a large multispecialty medical center. Patients with a partially edentulous jaw who had received endosseous implants to support and retain dental prostheses were included in this review. Implant survival and fracture, prosthetic complications, and demographic data were recorded and analyzed through Kaplan-Meier methods. RESULTS: A total of 1170 implants were placed in four anatomic locations: anterior maxilla, posterior maxilla, anterior mandible, or posterior mandible. Location of implants was shown to have no effect on implant survival (p = 0.7398), implant fracture rates (p = 0.2385), screw loosening (p = 0.8253), or screw fracture (p = 0.2737). Development of new restorative components has resulted in significantly better rates of implant survival without fracture (p = 0.0054), screw function without loosening (p < 0.0001) and screw function without fracture (p = 0.0013). Implant survival seems to have been improved with the new components (p = 0.0513). CONCLUSIONS: Implant survival in this study was independent of anatomic location of implants. Virtually all clinical performance factors were improved by design changes in implant restorative components that were brought to market in early 1991.     

Gingival fluid tetracycline release from bioerodible gels

Intracrevicular antimicrobial therapy is consistent with the site-specific nature of periodontitis. Considerable research has focused on the use of nonresorbable fibers. However, a bioerodible system is desirable. The purpose of this study was to assess tetracycline release and safety following a single application of a syringable 35% tetracycline hydrochloride in a lactic-glycolic acid gel. 31 generally healthy adult volunteers (mean age = 59 years) were enrolled in and completed this randomized, double-blind eight day study. 2, 6-10 mm non-adjacent interproximal pockets that bled on pocket probing were chosen as experimental sites in each subject. I experimental site and the surrounding gingival crevice received small particle size tetracycline in gel while the other site received larger particle size tetracycline in gel. Gingival crevicular fluid (GCF) was collected prior to treatment and 15 min, 1, 2, 3, 4 and 8 days post-treatment. GCF tetracyline concentrations were determined by agar diffusion bioassay and GCF volume measurements. 61% and 71% of sites had > or = 100 micrograms/ml tetracycline 3 days following application of large (mean concentration = 430 +/- 92 micrograms/ml) and small particle gels (mean concentration = 418 +/- 70 micrograms/ml), respectively. 37% and 55% of sites had measurable tetracycline 8 days after placement of large (mean concentration = 86 +/- 31 micrograms/ml) and small particle gels (mean concentration = 293 +/- 79 micrograms/ml), respectively. The most common adverse event was "bitter taste" (10% of subjects). Based upon the reduction in probing depths and % of sites bleeding on probing at 8 days relative to pretreatment, and the absence of any serious adverse events, it is concluded that these bioerodible gels are safe, and since the bacteriostatic range for most putative periodontopathogens is in the 2-10 micrograms/ml range, the tetracycline levels observed at days 3 and 8 likely represent significant antimicrobial efficacy.     

Advanced surgical procedures: bone augmentation

Over the last ten years there has been a significant increase in the range and type of edentulous defects that can be treated using osseointegrated implants. Encouraged by the long-term success of implant reconstructions in the edentulous mandible and maxilla, and the availability of novel implant attachments, clinicians will now undertake more elaborate treatment involving the partially edentate and those with localized or generalized tissue deficiencies. This clinical trend places increasing demands on the predictability, complexity and accuracy of the surgical procedure necessary to allow a successful prosthetic reconstruction. This is especially so when potential implant sites lie in areas of high aesthetic or functional requirements.