Catherine Giannopoulou

Functional Characteristics of Gingival and Periodontal Ligament Fibroblasts

In periodontal surgery, healing after Guided Tissue Regeneration (GTR) may be explained by differences in functional activities of gingival and periodontal ligament fibroblasts (GF and PDLF). Several studies in vitro have supported this hypothesis, but much remains to be defined. In the present work, gingival and periodontal ligament fibroblasts derived from five healthy subjects were isolated and compared in vitro. The morphology of the cells was observed under scanning electron microscopy (SEM). Several extracellular matrix components (ECM) were studied to compare the effects on fibroblast attachment, proliferation, and protein synthesis. Several biochemical markers were examined in both cellular extract (CE) and conditioned medium (CM). We also examined the muscle differentiation markers alpha-smooth muscle actin, desmin, and smooth-muscle myosin. Finally, we studied the effects of epithelial cells on the proliferation and protein synthesis of the two types of fibroblasts. GF and PDLF appeared identical under the SEM. All ECM components enhanced attachment; however, while collagen types I and IV promoted the attachment of GF, gelatin, laminin, and vitronectin promoted that of PDLF. Most ECM components increased the proliferation rate of GF and the biosynthetic activity of PDLF. The biochemical markers were similarly distributed between the two cell types, except for alkaline phosphatase, which was detected only in the CE of PDLF. Both GF and PDLF strongly expressed alpha-smooth-muscle actin and were negative for desmin; only PDLF were positive for smooth-muscle myosin. Epithelial cells increased the proliferation of both GF and PDLF but had no effect on their biosynthetic activity. These in vitro results may better explain the in vivo functional differences between GF and PDLF.

Detection of apical root resorption after orthodontic treatment by using panoramic radiography and cone-beam computed tomography of super-high resolution

INTRODUCTION Apical root resorption is an adverse side effect of orthodontic treatment. We compared panoramic radiography (OPT) with cone-beam computed tomography (CBCT) in evaluating orthodontically induced apical root resorption. METHODS The study sample comprised 275 teeth in 22 patients near the end of orthodontic treatment with fixed appliances. Two calibrated examiners assessed blindly the presence or absence and the severity of apical root resorption on the OPT images after treatment and the corresponding reconstructed CBCT images. Resorption was evaluated as no, mild, moderate, severe, and extreme. RESULTS On the OPT images, 17 teeth (6.2%) could not be evaluated. Statistically significant differences were found between the 2 methods: 56.5% and 31% of the teeth showed no resorption by OPT and CBCT, respectively; 33.5% and 49% of the teeth showed mild resorption, whereas 8% and 19% showed moderate resorption by OPT and CBCT, respectively. Severe resorption was found in only 2 teeth by CBCT. CONCLUSIONS Apical root resorption after orthodontic tooth movement is underestimated when evaluated on OPT. CBCT might be a useful complementary diagnostic method to conventional radiography, to be applied when a decision on continuation or modification of the orthodontic treatment is necessary because of orthodontically induced root resorption.

Neutrophil Elastase and its Inhibitors in Human Gingival Crevicular Fluid during Experimental Gingivitis

The relative concentrations and absolute amounts of neutrophil elastase and its two inhibitors, α2-macroglobulin (α2-M) and alantitrypsin (α1-AT), were determined in gingival crevicular fluid (GCF) collected from six dental students who refrained from brushing the upper left or right quadrant during three weeks. Plaque and gingival indices and flow of GCF were measured before, during, and after the three weeks of no brushing. Functional elastase, representing the enzyme complexed with a2-M, was measured by use of a low-molecular-weight fluorogenic substrate. Elastolytic activity in GCF was also assayed by use of elastin as substrate. Antigenic elastase, representing the enzyme complexed with a 1-AT, as well as the inhibitors a2-M and al-AT were measured by ELISA. After three weeks of plaque accumulation, the concentrations of both functional and antigenic elastase increased by a factor of about 3, whereas the concentrations of the inhibitors increased in a much higher proportion. No free elastase could be detected in GCF, as evidenced by the Sephadex G-75 elution profile of GCF, by the negative results obtained when elastin was used as substrate, and by the demonstration that pure enzyme kept its activity against the low-molecular-weight substrate after being saturated by a2-M.

Microbiologic testing and outcomes of full-mouth scaling and root planing with or without amoxicillin/metronidazole in chronic periodontitis.

BACKGROUND It has been suggested that use of systemic antibiotics should be limited to patients with specific microbiologic profiles. The main purpose of the present analysis was to study whether microbiologic testing before therapy was of value in predicting which patients would specifically benefit from adjunctive amoxicillin and metronidazole, given in the context of full-mouth scaling and root planing (SRP) within 48 hours. METHODS This was a 6-month, single-center, double-masked, placebo-controlled, randomized longitudinal study. Fifty-one patients received full-mouth periodontal debridement, performed within 48 hours; then, 25 subjects received metronidazole, 500 mg, and amoxicillin, 375 mg, three times a day for 7 days, and 26 received a placebo (control group). Pooled microbiologic samples were taken from the deepest pocket at baseline in each quadrant before and 6 months after treatment. Six periodontal pathogens were quantified by real-time polymerase chain reaction. RESULTS Forty-seven patients were followed for 6 months. After treatment, test subjects had a substantially lower mean number of persisting sites with probing depth >4 mm and bleeding on probing than did control subjects (0.4 versus 3.0; P = 0.005; month 6). Aggregatibacter actinomycetemcomitans (previously Actinobacillus actinomycetemcomitans) could not be detected in the antibiotic group after treatment. However, in the placebo group, three of six subjects positive for A. actinomycetemcomitans continued to be positive. Lower frequencies were also noted in the test group for Porphyromonas gingivalis (P = 0.013) and Tannerella forsythia (previously T. forsythensis) (P = 0.007). However, even subjects testing negative for A. actinomycetemcomitans at baseline had a significantly better primary clinical outcome if they received the active drugs. The presence of six putative periodontal pathogens (A. actinomycetemcomitans, Fusobacterium nucleatum spp., P. gingivalis, Prevotella intermedia, Treponema denticola, and T. forsythia) quantified prior to therapy was not correlated with the outcome of full-mouth SRP with or without amoxicillin and metronidazole. CONCLUSION Excellent clinical results in the antibiotics group were obtained regardless of the presence or absence of six classic periodontal periopathogens prior to treatment.

Effect of Photodynamic Therapy, Diode Laser, and Deep Scaling on Cytokine and Acute-Phase Protein Levels in Gingival Crevicular Fluid of Residual Periodontal Pockets

BACKGROUND There is an ongoing controversy on the benefits of treatment protocols, including dental lasers and photodynamic therapy (PDT). The purpose of this study is to compare the local biologic effects of PDT, diode soft laser (DSL) therapy, and conventional deep scaling and root planing (SRP) in residual pockets. METHODS Thirty-two individuals were included based on a history of previous treatment for periodontitis and the persistence of sites with probing depths >4 mm and bleeding on probing. Residual pockets were debrided with an ultrasonic device and then randomly assigned either to PDT, DSL, or SRP. Gingival crevicular fluid was collected before treatment, after 14 days, and at 2 and 6 months. Levels of 13 cytokines and nine acute-phase proteins were measured using a bead-based multiplexing analysis system. RESULTS Treatment with PDT, DSL, or SRP led to significant changes in several cytokines and acute-phase proteins: Compared with baseline, levels of interleukin-17, basic fibroblast growth factor, granulocyte colony-stimulating factor, granulocyte macrophage colony-stimulating factor, and macrophage inflammatory protein 1-α were lower 14 days and 2 months after treatment. Except for granulocyte colony-stimulating factor, these differences remained significant throughout the observation period. The levels of five acute-phase proteins (α-2 macroglobulin, haptoglobin, serum amyloid P, procalcitonin, and tissue plasminogen activator) were significantly higher at 6 months than at baseline. No significant differences were observed among the three treatment modalities at any time point for any biochemical parameter. CONCLUSIONS Levels of several cytokines and acute-phase proteins significantly changed after treatment regardless of treatment modality. There was no evidence for a specific DSL- or PDT-enhanced expression of inflammatory mediators.

Diagnostic accuracy of digitized periapical radiographs validated against micro-computed tomography scanning in evaluating orthodontically induced apical root resorption

The aim of this study was to validate the use of digitized periapical radiographs in evaluating orthodontically induced apical root resorption against micro-computed tomography (micro-CT) scanning as a criterion standard test. In a standardized experimental protocol, 29 premolars in 16 subjects were tipped buccally for 8 wk. Nineteen contralateral premolars not subjected to orthodontic movement served as controls. Standardized periapical radiographs were taken before and after the experimental period (Rx method). These teeth were extracted and scanned using a micro-CT technique with a 9 mum resolution. Two calibrated examiners assessed blindly the presence or absence of apical root resorption on digitized radiographs and three-dimensional reconstructions of the scans. Significant differences were detected between the orthodontically moved teeth and controls: 86% of the orthodontically moved teeth and 21% of the control teeth showed apical root resorption when using micro-CT as a validation method. A total of 55% of the experimental teeth and 5% of the control teeth showed resorption when assessed using Rx method. The Rx method showed a specificity of 78% and a sensitivity of 44%, which means that less than half of the cases with root resorption identified using a CT scanner were identified by radiography. Nearly all the orthodontically moved teeth showed apical root resorption. Apical root resorption may be underestimated when evaluated using digitized periapical radiographs.

Are There Specific Benefits of Amoxicillin Plus Metronidazole in Aggregatibacter actinomycetemcomitans-Associated Periodontitis? Double-Masked, Randomized Clinical Trial of Efficacy and Safety

BACKGROUND It has been suggested that prescription of amoxicillin plus metronidazole in the context of periodontal therapy should be limited to patients with specific microbiologic profiles, especially those testing positive for Aggregatibacter actinomycetemcomitans. The main purpose of this analysis is to determine if patients positive for A. actinomycetemcomitans with moderate to advanced periodontitis benefit specifically from amoxicillin plus metronidazole given as an adjunct to full-mouth scaling and root planing. METHODS This is a double-masked, placebo-controlled, randomized longitudinal study including 41 participants who were positive for A. actinomycetemcomitans and 41 participants who were negative for A. actinomycetemcomitans. All 82 patients received full-mouth periodontal debridement performed within 48 hours. Patients then received either systemic antibiotics (375 mg amoxicillin and 500 mg metronidazole, three times daily) or placebo for 7 days. The primary outcome variable was persistence of sites with a probing depth (PD) >4 mm and bleeding on probing (BOP) at the 3-month reevaluation. Using multilevel logistic regression, the effect of the antibiotics was analyzed according to the following factors (interaction effect): A. actinomycetemcomitans-positive or -negative at baseline, sex, age, smoking, tooth being a molar, and interdental location. RESULTS At reevaluation, participants in the test group had significantly fewer sites with a persisting PD >4 mm and BOP than control patients (P <0.01). Being A. actinomycetemcomitans-positive or -negative did not change the effect of the antibiotics. Patients benefited from the antibiotics irrespective of sex, age, or smoking status. Molars benefited significantly more from the antibiotics than non-molars (P for interaction effect = 0.03). CONCLUSIONS Patients who were positive for A. actinomycetemcomitans had no specific benefit from amoxicillin plus metronidazole. Sites on molars benefited significantly more from the antibiotics than non-molar sites.

The NADPH oxidase NOX2 plays a role in periodontal pathologies

Oxidative stress plays an important role in periodontal health and disease. The phagocyte nicotinamide adenine dinucleotide phosphate oxidase NOX2 is most likely one of the key sources of reactive oxygen species (ROS) in periodontal tissues. This review will discuss three clinical aspects of NOX2 function. We will first focus on oral pathology in NOX2 deficiency such as chronic granulomatous disease (CGD). CGD patients are thought to suffer from infections and sterile hyperinflammation in the oral cavity. Indeed, the periodontium appears to be the most common site of infection in CGD patients; however, as periodontitis is also common in the general population, it is not clear to which extent these infections can be attributed to the disease. Secondly, the role of oxidative stress in periodontal disease of diabetic patients will be reviewed. Diabetes is indeed a major risk factor to develop periodontal disease, and increased activity of leukocytes is commonly observed. Enhanced NOX2 activity is likely to be involved in the pathomechanism, but data remains somewhat preliminary. The strongest case for involvement of NOX2 in periodontal diseases is aggressive periodontitis. Increased ROS generation by leukocytes from patients with aggressive periodontitis has clearly been documented. This increased ROS generation is to be caused by two factors: (1) genetically enhanced ROS generation and (2) oral pathogens that enhance NOX function. NOX enzymes in the oral cavity have so far received little attention but are likely to be important players in this setting. New therapies could be derived from these new concepts.

Factors related to the rate of orthodontically induced tooth movement

INTRODUCTION The purpose of this study was to investigate the variations of orthodontically induced tooth movement in the maxillary and mandibular arches between patients and the factors such as age, sex, and presence of an interference that might influence the amount of tooth displacement. METHODS By using a standardized experimental orthodontic tooth movement in 30 subjects, 57 premolars were moved buccally during 8 weeks with the application of a 1-N force. Forty-four contralateral premolars not subjected to orthodontic tooth movement served as the controls. Plaster models from before and after the experimental tooth movement were digitized and superimposed to evaluate the amounts of tooth movement. Differences in tooth movement between the experimental and control groups were tested by an unpaired t test. For the experimental teeth, subject-related factors (age and sex) and tooth-related factors (location in the maxillary or mandibular dental arch, and the presence or absence of an intra-arch or interarch obstacle such as neighboring touching teeth or teeth interfering with the occlusion) were examined with analysis of variance. Multiple linear regression analysis was performed to determine correlations between tooth displacement, age, sex, tooth location, and presence of an interference. RESULTS Each subject contributed at least 2 experimental premolars and 1 control premolar. The displacement of the orthodontically moved teeth was 2.42 mm (range, 0.3-5.8 mm). Younger subjects (<16 years; n = 19; number of teeth, 36) had significantly greater amounts of tooth displacement compared with older subjects (≥16 years; n = 11; number of teeth, 21): 2.6 ± 1.3 mm vs 1.8 ± 0.8 mm; P <0.01. When an interarch or intra-arch obstacle was present, the amount of tooth movement was significantly less (2.6 ± 1.3 mm vs 1.8 ± 0.8 mm) (P <0.05). Neither sex nor the location of the experimental teeth in the mandible or the maxilla had any effect. CONCLUSIONS Younger patients showed greater tooth movement velocity than did older ones. An interarch or intra-arch obstacle decreased the amount of tooth displacement.

Root-contact evaluation by panoramic radiography and cone-beam computed tomography of super-high resolution.

INTRODUCTION Correct tooth position in the 3 planes of space is a major objective of orthodontic treatment. The aim of this study was to determine whether a panoramic radiograph (OPT) provides a true assessment of the mesiodistal root relationship of adjacent teeth. METHODS OPTs of 22 patients near the end of treatment with fixed appliances in both arches were taken before debonding. When the roots of adjacent teeth were touching on the OPT, cone-beam computed tomography (CBCT) was used to show the true root relationships. RESULTS We evaluated 235 interdental sites by OPT and CBCT; 47 areas showed contact between adjacent roots in the OPT images. However, the CBCT images showed true contact in only 5 of these areas; ie, 11% of the diagnoses based on OPT images were true positive, whereas the rest (89%) was false positive. One hundred eighty-eight sites showed no contact in the OPT images; this was confirmed by CBCT. CONCLUSIONS OPT has high sensitivity and relatively high specificity to detect adjacent roots touching each other. Root contacts are overestimated when evaluated by OPT.