Syndecan-1 immunohistochemical expression in gingival tissues of chronic periodontitis patients correlated with various putative factors

BACKGROUND AND OBJECTIVE

Limited information is available on the expression and distribution of syndecan-1 within human gingival tissues/cells and on putative factors that might affect its expression. Therefore, the objective of the present study was to determine immunohistochemically the expression and distribution of syndecan-1 in the gingival tissues of patients with chronic periodontitis and to examine the correlation of syndecan-1 expression with various putative factors (environmental, patient/systemic and local factors).

MATERIAL AND METHODS

Gingival specimens were surgically excised from the area of the junctional/pocket epithelium (study group 1, including 30 chronic periodontitis patients) or the gingival oral epithelium (study group 2, comprising another 30 chronic periodontitis patients), adjacent to teeth with poor prognosis. Standard two-step immunohistochemistry and semi-quantitative evaluation of immunohistochemical staining were used to determine syndecan-1 expression. Statistical analyses on the impact of various putative factors were performed.

RESULTS

In the junctional/pocket epithelium or the oral epithelium, syndecan-1 expression was weak to moderate in the suprabasal and basal epithelial cells and absent to weak in the internal basal lamina, external basal lamina and gingival connective tissue matrix. Syndecan-1 expression in the junctional/pocket epithelium was statistically significantly stronger than in the oral epithelium in inflammatory cells within the underlying gingival connective tissue (primarily plasma cells and lymphocytes) and in scattered fibroblast-like cells.

CONCLUSIONS

Syndecan-1 expression in the junctional/pocket epithelium or the oral epithelium can exhibit a significant positive correlation with the severity/degree of histologically evaluated local gingival inflammation, but in general is not significantly correlated with age, smoking, full-mouth and local clinical (probing pocket depth and clinical attachment level) and radiographical parameters (radiographical bone loss) of periodontal status.

Fractured prosthetic abutments in osseointegrated implants: a technical complication to cope with

In the present report a repair set to retrieve fractured abutments remaining in the implants of the ITI Dental Implant System is presented. In 1 case in which such fractures occurred, the repair set was successfully applied. After removal of all particles of the fractured prosthetic abutments and recutting the threads, new abutments were used, and the original suprastructure could be reinserted. The causes for such technical failures are discussed considering the relatively sparse information in the literature on that topic.

Generalizability of the added benefits of guided tissue regeneration in the treatment of deep intrabony defects. Evaluation in a multi-center randomized controlled clinical trial

BACKGROUND

Several studies have shown that GTR therapy of intrabony defects results in significantly better outcomes than access flap alone. Most of the available data, however, have been produced in highly controlled research environments by a small group of investigators. Generalizability of results to different clinicians and different subject populations has not been evaluated so far.

METHODS

This parallel group study involved 143 patients recruited in a practice-based research network of 11 offices in 7 countries. It was designed to evaluate: 1) the applicability of the documented added benefits of GTR in the treatment of intrabony defects to different populations, and 2) the generalizability of the expected results to different clinicians. GTR was compared to access flap alone. Defects, one in each patient, were accessed with a previously described papilla preservation flap in both the test and control group. In addition, GTR sites received application of a bioabsorbable poly-D,L-lactide-co-glycolide membrane. A stringent plaque control regimen was enforced in all patients during the 1-year observation period. Outcomes included gains in clinical attachment (CAL) and reductions in probing depth.

RESULTS

Observed gains in CAL were 2.18 +/- 1.46 mm for access flap and 3.04 +/- 1.64 mm for the GTR-treated group. The treatment-associated difference was statistically significant (P = 0.03) after correcting for both center effect and defect anatomy. Among the various centers, a 1.73 mm difference in CAL gain was observed. This is a clinically relevant amount, which underlines the significance of center variability in the outcome of periodontal surgical procedures. A frequency distribution analysis of the obtained CAL gains indicated that GTR treatment of deep intrabony defects decreased, with respect to the access flap control, the probability of obtaining only a modest attachment gain at 1 year. Conversely, CAL gains of 4 mm or more were observed in more than 40% of GTR-treated defects and in less than 20% of the controls (P < 0.0001).

CONCLUSIONS

These data indicate that GTR therapy of deep intrabony defects performed by different clinicians on various patient populations resulted in both greater amounts and improved predictability of CAL gains than access flap alone.

Evaluation of tetracycline fiber therapy with digital image analysis

The aims of the present study were to assess radiographically the effects of scaling/root planing combined with antibiotic therapy using tetracycline fibers (TCF): (I) on alveolar bone density and linear descriptors and (II) on supracrestal soft tissue density. 19 subjects with generalized adult periodontitis (with at least 20 teeth present, at least 4 teeth with pockets >4 mm and bleeding upon controlled force probing) and high cultural counts of Porphyromonas gingivalis were recruited from a pool of 57 patients. The full mouth treatment group (FT) consisted of 10 patients, who underwent a full mouth supra-gingival scaling and prophylaxis treatment and were instructed to rinse 2x daily with a 0.1% chlorhexidine solution. 1 week later, tetracycline-hydrochloride-containing fibers (Actisite periodontal fiber) were applied around all teeth. After 7-12 days, the fibers were removed and all teeth were scaled and root planed under local anaesthesia. The chlorhexidine rinsing continued for another 2 months. In 9 subjects (local treatment group LT), 2 teeth with periodontal lesions with pocket probing pepth (PPD) > or =5 mm were treated by placement of tetracycline fibers, which remained in place for 7 to 12 days. Upon removal of the fibers, scaling and root planing was performed on these 2 teeth, while the rest of the dentition remained untreated, and no chlorhexidine rinse was applied. 2 of the untreated teeth revealing similar periodontal lesions were chosen to represent sites affected by untreated periodontitis (NT). In this group, a limited local treatment was performed (2 teeth) with the inherent potential for recolonization from the untreated pocket sites. Standardized periapical radiographs were obtained from the 4 monitored sites within each patient at baseline (before treatment) and 2 and 6 months thereafter. One radiograph was exposed in a standard way for bone assessment. The second radiograph was underexposed, at about a 1/5 of the original exposure time to allow the evaluation of soft tissue. Mean changes in the linear parameters and changes in density (CADIA) observed at multiple sites within each patient and treatment group were used as the best estimate of treatment outcome. Over the observation period of 6 months, a significant difference in bone height changes was found between the untreated sites (median loss -0.29 mm) and the sites from full-mouth treated patients (median gain 0.24 mm, p=0.008). When comparing the baseline to the 6 months radiographs, a loss in bone density was observed for the untreated group (median=-2.13 CADIA). Both treatment groups revealed a gain in density (median=1.58 and 2.43 CADIA for the locally and the full-mouth treated groups, respectively). Differences in density were significant, both between the nontreated and locally treated sites (p=0.026) and between the nontreated sites and the sites from the full mouth treated patients (p=0.002). The analysis of the soft tissues showed a similar pattern of changes in density to those seen in the bone defect. At 2 months, there was a tendency for loss in density for the nontreated group (median=-0.17 CADIA) that continued over the 6 month period (median=-0.31 CADIA). A significant increase in density was observed for the full-mouth treated sites (median=1.57 and 0.64 CADIA for the 2 and 6 months radiographs, respectively). A significant increase was also observed for the locally treated group when compared to the untreated sites (median=0.13 and 0.10 CADIA for the 2 and 6 months radiographs, respectively). Comparing untreated sites with full-mouth treated sites, a significant difference was observed for CADIA measurements (p<0.001). No significant difference was observed comparing locally treated and untreated sites (p=0.24). It was concluded that scaling and root planing combined with TCF therapy can result in increased bone density and alveolar bone height. Full-mouth treatment seemed to result in more pronounced gains compared to local tre

Computer-assisted densitometric image analysis of digital subtraction images: in vivo error of the method and effect of thresholding

The aim of the present study was to assess the in vivo error of the method as well as the effect of thresholding when obtaining and evaluating standardized periapical radiographs for computer-assisted densitometric image analysis (CADIA). Twenty healthy volunteers participated in an experimental gingivitis study in which neither mechanical nor chemical plaque control was performed for 21 days. Two pairs of standardized periapical radiographs were taken at days 0 (baseline) and 21 (follow-up), one from a maxillary area (15 volunteers) and one from a mandibular molar/premolar area (17 volunteers). Each baseline radiograph was digitized and its image displayed on a monitor. The follow-up radiograph was then superimposed and digitized as well. After gray level correction, subtraction radiographic images were produced. The difference in gray level between the baseline and the follow-up image was calculated within each region of interest (ROI) at each picture point (pixel). In bone ROI, changes in density reflected the amount of change due to methodological errors plus the basic bone remodeling over 3 weeks. For gingival ROI, changes in density reflected the methodological error plus a possible change in soft tissue density during the experimental gingivitis. Within all of the ROI, some pixels indicated a change in gray level. A change in gray level was then thresholded; i.e., only changes >5 and then >10 gray levels were registered and used for calculation of the CADIA values. With a threshold of 5, 44/45 maxillary bone ROI and 60/66 mandibular bone ROI showed a change in density, while 41/45 maxillary gingiva ROI and 26/66 mandibular gingiva ROI indicated a change in density. With a threshold of 10, 16/45 maxillary bone ROI and 12/66 mandibular bone ROI indicated a change in density, while 13/45 maxillary gingiva ROI and 1/66 mandibular gingiva ROI indicated a change. The amounts of changes in density calculated in the various ROI were low even when applying no threshold, ranging from -0.279 to 0.621. Applying a threshold of 5, the CADIA values ranged from -0.234 to 0.727. With a threshold of 10, the changes in density ranged from -0.318 to 0.133. In vivo, CADIA of standardized radiographs indicated change in density due to methodological errors. Application of thresholds may avoid false-positive diagnoses. When applying CADIA in clinical research, the range of change to be expected due to methodological limitations as well as the threshold for true change should be evaluated. These thresholds may differ in various areas of the mouth, i.e., bone or gingival, maxillary/mandibular, anterior/posterior ROI.

Effect of the NSAID flurbiprofen on remodelling after periodontal surgery

The aim of the present experiment was to assess the effect of the administration of the NSAID flurbiprofen (Froben) on tissue healing after periodontal surgery. Sites from patients with the same treatment modality (modified Widman flap) but receiving a placebo drug and sites within each patient not exposed to surgery served as controls. Nineteen patients suffering from moderate to severe periodontal disease were recruited and they signed informed consent forms. These patients required periodontal surgery as assessed at the periodontal re-evaluation. The sites chosen for the study were all diagnosed with PPD > or = 5 mm and were bleeding on probing. During the healing phase 10 patients received 50 mg Froben 3 times per day for 30 d whereas 9 patients received a placebo drug. Two sites with PPD > or = 5 mm after initial therapy and bleeding on probing served as surgical sites, whereas 2 similar sites were not exposed to surgery. The study design was set up double-blind. The radiographic examination consisted of 2-4 standardized vertical bitewings obtained at the periodontal re-evaluation (BL) at 1, 3 and 6 months post-surgically for digital subtraction and computer assisted densitometric image analysis (CADIA). The regions of interest analysed were mesial or distal crestal sites. Minimal remodelling activity was observed radiographically after periodontal surgery in both patient groups. There were no statistically significant differences between the four groups of sites regarding the mean changes in density when analysing the pairs of radiographs 0-1, 0-3, 0-6 months. A frequency analysis was performed to list the number of sites with different ranges of density change. No differences in the distributions of the numbers of sites were observed when comparing the 4 site groups (Kolmogorov-Smirnov, p > 0.05). A significant reduction of the probing pocket depth and a significant amount of clinical attachment gain was noted at the surgically treated sites irrespective of whether the patients had used flurbiprofen or placebo. Whereas the pathways leading to bone resorption in periodontally diseased sites have been shown, in other studies, to be influenced by NSAID, the results of the present study could not justify general administration of Froben for the purpose of reduction of bone resorption after periodontal surgical procedures in patients with adult periodontitis.

Use of an internal standard in subtraction radiography to assess initial periodontal bone changes

OBJECTIVE

To assess the use of an internal reference when performing histogram analyses in digital subtraction images and to determine the ability of the method to detect initial bone lesions.

METHODS

Fifty-one Royal Air Force recruits had standardized vertical bitewing radiographs and clinical assessment of attachment level recorded annually over three years. Subtraction analyses of crestal bone changes at the mesial surface of the upper right first molar were compared with changes at the mesial surface of the same tooth. Changes over the periods from age 17 to 18 years and age 18 to 20 years were monitored using two subtraction procedures.

RESULTS

Reproducibility studies revealed that Pearson correlations between duplicate measurements of the test site alone (16 crest; r = 0.74) were lower than those between duplicate measurements of changes where misalignment was controlled for, either as a difference (16 crest-16 tooth; r = 0.93) or ratio (16 crest/16 tooth; r = 0.93). We used the differences between the mean subtraction density for 16 crest and 16 tooth as our measure of change in bone density. For the duplicate measurements, the standard deviation of these differences was 3.9: a difference of +/- 7.8 was therefore taken as a threshold value for evidence of real change. Bone gain was noted between the ages of 17 and 18 years (16/21 subjects), but some early bone loss was seen between 18 and 20 years (12/21 subjects), with four subjects showing changes significantly greater than the method error. There were no associations between the clinical and radiographic observations.

CONCLUSION

Use of a control site in subtraction radiography improves the reproducibility; such systems can detect small changes in alveolar bone which may assist in early diagnosis of the initial periodontal lesion which may precede observable clinical changes.

Successful bone fill in late peri-implant defects using guided tissue regeneration. A short communication

Severe loss of peri-implant supporting bone traditionally leads to the removal of the affected implant, but this may not be necessary in all cases. This paper presents a novel treatment approach aimed at the successful regeneration of bone lost to peri-implantitis using guided tissue regeneration (GTR). Four years after implant placement two patients presented with severe peri-implant tissue breakdown. Clinical signs of disease included bleeding on probing, suppuration, increased probeable pocket depth (4 to 9 mm) and a decreased level of clinical attachment (2 to 10 mm). Radiographic analysis revealed 2.6 to 7.1 mm loss of supporting bone. Treatment of these lesions included raising flaps, wound debridement, and rinsing with sterile saline and 0.2% chlorhexidine digluconate. Subsequently, ePTFE membranes were adapted around the necks of the implants and the flaps sutured around the necks of the implants, allowing for transmucosal healing. Both patients were placed on a 10-day antibiotic regimen and instructed to rinse twice daily with a 0.12% chlorhexidine solution. They were reevaluated every 3 weeks at which time professional plaque control was performed. After 4 1/2 and 6 1/2 months, respectively, the membranes required removal due to infection. The radiographic analysis 1 year after membrane removal revealed 1.5 to 3.6 mm of bone gain. As a result of regenerative therapy the implants in both these patients were successfully maintained. It can be concluded that implants with severe loss of bone resulting from peri-implantitis need not always be extracted. A potential approach for the treatment of peri-implant bone destruction is GTR therapy using strict attention to good antimicrobial therapy.

Guided bone regeneration around an immediate transmucosal implant for single tooth replacement: a case report

This case report describes the procedure of guided bone regeneration around an endosseous dental implant, placed into an extraction alveolus in the absence of total soft tissue coverage, ie, in a transmucosal condition. The technique presented permits an immediate placement of the implant after the extraction of the maxillary right lateral incisor. A nonresorbable barrier membrane was used, and strict chemical plaque control was maintained during osseointegration. After an uneventful healing period of 6 months, the membrane was removed in a second-stage surgery. Two months later, the fixed single tooth prosthesis was placed. The learning objective of this article is to explain the immediate transmucosal implant surgery technique, using a case report to illustrate the procedure.

Digital image processing. II. In vitro quantitative evaluation of soft and hard peri-implant tissue changes

The aim of this study was to evaluate the ability of computer-assisted densitometric image analysis (CADIA) to detect small changes in mineralized and nonmineralized tissues adjacent to dental implants and to correlate these changes with CADIA values. A section of a pig mandible including all soft tissues and in which a hollow cylinder ITI Bonefit implant with an artificial mesial and a buccal infrabony defect was placed was used to obtain pairs of standardized radiographs. Series of radiographs were obtained with exposure times of 0.13, 0.20, 0.44, and 0.53 s. Specimens of mineralized or nonmineralized tissues were placed arbitrarily in the defects before each radiographic exposure. The radiographs were captured through a video camera, digitized and stored in a personal computer. Every radiographic image was then subtracted from a baseline one without any change. The result of the subtraction was evaluated with CADIA. A linear correlation (r2 = 0.99) was found between the bone chips (1-5 mg of dry weight) placed in the mesial defect and the CADIA values. Bone chips in the buccal defect (behind the implant), however, were not detected unless their weight reached 14 mg or more. For conventionally exposed radiographs, it was not possible to recognize soft tissue specimens (1-6 mg), either in the buccal or the mesial defect. However, when "underexposed" radiographs (exposure time: 0.13 s) were obtained, a linear correlation (r2 = 0.80) was calculated for soft tissue specimens in the mesial defect and CADIA values. In normally exposed radiographs, the CADIA system could detect even the smallest change in bone density (bone chip of 1 mg of dry bone weight) and correlated almost linearly with these changes. Provided that the radiographic images are obtained with standardized geometry and normal exposure time, the tissue density changes detected by this system within bone defects represent only mineralized tissue changes. By underexposing radiographs, CADIA may even reveal soft tissue changes around dental implants.

Digital image processing. I. Evaluation of gray level correction methods in vitro

The aims of this study were a) to assess in an in vitro model the amount of density changes measured in digitally subtracted images due to electronic noise and image alignment error, and b) to test the accuracy of different gray level correction procedures in the reduction of densitometric image mismatches. A section of a pig mandible in which a hollow cylinder ITI Bonefit implant had been placed was used to obtain pairs of standardized radiographs. Series of radiographs were obtained with different exposure times (0.34, 0.39, 0.44, 0.51, 0.58 s). The radiographs were captured through a video camera, digitized and stored in a personal computer. The same radiographic image was recorded and subtracted from itself 10 times to study the error of the method due to electronic transformations of the images and image alignment. The noise due to the analog-to-digital transformation of the radiographic images was calculated to be +/- 2 gray levels i.e., 2% of the scale of gray levels. This kind of error was reduced up to 40% by capturing the images more than once and averaging the values per pixel. The manual superimposition of the images to be subtracted caused an increase of the error to +/- 3 gray levels (2.7%). Seven methods of gray level correction based either on a linear least squares approximation or on the cumulative density function (CDF) were tested. The group based on the CDF algorithm gave significantly better results than any other method. Pixels yielding differences smaller or equal to +/- 7 gray levels (5.5% of the scale of gray levels) should be excluded from further calculations in order to eliminate (false-positive) errors due to the normalizing algorithms. Furthermore, the CDF method on an arbitrarily chosen area of the image or on the wedge seems to give to subtraction images the ability of revealing real subtle changes in tissue density (fewer false-negative errors). The use of reference structures did not futher improve the ability of the normalization methods to correct gray level mismatches between radiographic pairs.

Treatment of an early implant failure according to the principles of guided tissue regeneration (GTR)

The present case report demonstrates the application of guided tissue regeneration (GTR) in combination with antimicrobial therapy for the treatment of an early implant failure. This treatment approach both prevented further loss of bone as well as led to the regeneration of lost bone. By means of color-converted digital subtraction images, remodelling of the tissues adjacent to the defect was documented as early as one month postsurgically. The images demonstrated "bone-fill" in the apical portion of the defect and resorptive changes at the bone crest. This case report demonstrates that combined regenerative and antimicrobial therapy may be a successful treatment approach restoring osseointegration of dental implants following loss of bone due to infection. Continuously increasing bone-fill inside the defect was documented when comparing the radiograph obtained immediately before the GTR procedure and at months 1, 2, 4, 5 and 6 of the healing period, respectively. Clinical measurement obtained at the time of the surgery and at the time of the membrane removal confirmed the radiographic evidence of bone-fill by demonstrating new tissue resistant to probing in close contact to the implant surface at the site of the previous defect. Antimicrobial therapy included an antibiotic regimen during the 1st month of healing as well as topical rinses with an antiseptic (chlorhexidine) over the entire healing period of 6 months. As a result of this treatment approach, the implant was saved and could be used as an abutment for a bridge reconstruction.