Analysis of In Situ Protease Activity in Chronic Adult Periodontitis Patients: Expression of Activated MMP‐2 and a 40 kDa Serine Protease

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/141775/1/jper0353.pd

Variation in Periodontal Diagnosis and Treatment Planning Among Clinical Instructors

Consistency in clinical decision making may be necessary for reliable assessment of student performance and teaching effectiveness, yet little has been done to examine variation in periodontal diagnosis and treatment planning among dental school faculty. The purpose of this investigation was to examine variation among faculty in diagnosis and management of common periodontal diseases. Twenty-seven clinical instructors (periodontists, general dentists, dental hygienists, and first- and second-year periodontal graduate students) reviewed three web-based cases and answered a brief questionnaire focusing on radiographic interpretation, periodontal diagnosis, and treatment planning. Response rates for the three cases ranged from 62 percent to 70 percent. Clinical instructors’ rating of percent bone loss in the majority of cases varied between three descriptive categories for the same tooth. Greater consistency in periodontal diagnosis was noted within the graduate student group as compared to periodontal and dental hygiene faculty groups. Diagnoses offered for one of the three patients varied between gingivitis and chronic and aggressive periodontitis. Six to nineteen different treatment plans (many with subtle differences) were submitted for each of the three cases. Inter-rater variation was qualitatively more prevalent than intra-rater variation. To our knowledge, this is the first study to document substantial variation among instructors in radiographic interpretation, diagnosis, and treatment planning for common periodontal diseases. Qualitative judgments speculating on the impact of variability among dental school faculty on student performance and patient care can be made but as yet remain unknown. Consistent use of accepted practice guidelines and greater consensus-building opportunities may decrease variation among faculty and enhance dental education

Effect of rhPDGF-BB Delivery on Mediators of Periodontal Wound Repair

Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of tooth-supporting structures. This investigation examined the effect of the local delivery of PDGF-BB when combined with reconstructive periodontal surgery on local wound fluid (WF) levels of PDGF-AB, vascular endothelial growth factor (VEGF), and bone collagen telopeptide (ICTP) in humans with advanced periodontitis. Sixteen patients exhibiting localized periodontal osseous defects were randomized to one of three groups (β-TCP carrier alone, β-TCP + 0.3 mg/mL of recombinant human PDGF-BB [rhPDGF-BB], or β-TCP + 1.0 mg/mL of rhPDGF-BB) and monitored for 6 months. WF was harvested and analyzed for PDGF-AB, VEGF, and ICTP WF levels. Teeth contralateral to the target lesions served as controls. Increased levels of VEGF in the WF was observed for all surgical treatment groups with the 1.0 mg/mL rhPDGF-BB group showing the most pronounced difference at 3 weeks in the AUC analysis versus control (p < 0.0001). PDGF-AB WF levels were increased for the carrier alone group compared to both rhPDGFBB groups. Low-dose rhPDGF-BB application elicited increases in ICTP at days 3–5 in the wound healing process, suggesting a promotion of bone turnover at early stages of the repair process (p < 0.02). These results demonstrate contrasting inducible expression patterns of PDGF-AB, VEGF, and ICTP during periodontal wound healing in humans.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/63257/1/ten.2006.12.1441.pd

Variation in Periodontal Diagnosis and Treatment Planning Among Clinical Instructors

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153684/1/jddj002203372005693tb03919x.pd

Effect of rhPDGF-BB on bone turnover during periodontal repair

Purpose : Growth factors such as platelet-derived growth factor (PDGF) exert potent effects on wound healing including the regeneration of periodontia. Pyridinoline cross-linked carboxyterminal telopeptide of type I collagen (ICTP) is a well-known biomarker of bone turnover, and as such is a potential indicator of osseous metabolic activity. The objective of this study was to evaluate the release of the ICTP into the periodontal wound fluid (WF) following periodontal reconstructive surgery using local delivery of highly purified recombinant human PDGF (rhPDGF)-BB. Methods : Forty-seven human subjects at five treatment centres possessing chronic severe periodontal disease were monitored longitudinally for 24 weeks following PDGF regenerative surgical treatment. Severe periodontal osseous defects were divided into one of three groups and treated at the time of surgery with either: Β -tricalcium phosphate (TCP) osteoconductive scaffold alone (active control), Β -TCP+0.3 mg/ml of rhPDGF-BB, or Β -TCP+1.0 mg/ml of rhPDGF-BB. WF was harvested and analysed for local ICTP levels by radioimmunoassay. Statistical analysis was performed using analysis of variance and an area under the curve analysis (AUC). Results : The 0.3 and 1.0 mg/ml PDGF-BB treatment groups demonstrated increases in the amount of ICTP released locally for up to 6 weeks. There were statistically significant differences at the week 6 time point between Β -TCP carrier alone group versus 0.3 mg/ml PDGF-BB group ( p <0.05) and between Β -TCP alone versus the 1.0 mg/ml PDGF-BB-treated lesions ( p <0.03). The AUC analysis revealed no statistical differences amongst groups. Conclusion : This study corroborates the release of ICTP as a measure of active bone turnover following local delivery of PDGF-BB to periodontal osseous defects. The amount of ICTP released from the WF revealed an early increase for all treatment groups. Data from this study suggests that when PDGF-BB is delivered to promote periodontal tissue engineering of tooth-supporting osseous defects, there is a direct effect on ICTP released from the wound.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72239/1/j.1600-051X.2005.00870.x.pd

Activation of transforming growth factor ß in chondrocytes undergoing endochondral ossification

Transforming growth factor ß (TGF-ß) has well-documented roles in chondrocyte maturation and endochondral ossification, but the mechanisms of TGF-ß activation during these processes remain unclear. In this study, we analyzed TGF-ß activation in chick embryo resting, proliferating, and hypertrophic chondrocytes in culture. We found that both levels and activation of TGF-ß increased substantially with maturation. The majority of TGF-ß produced by resting cells over culture time remained latent, but a larger portion produced by proliferating and hypertrophic cells was activated with increasing maturation. Zymography of gelatin gels revealed that matrix metalloprotease 2 (MMP-2) and MMP-9 were expressed by each population and that MMP-13 characterized hypertrophic chondrocytes and to a lesser extent proliferating chondrocytes in late cultures. Treatment with pharmacologic agents revealed that both MMPs and serine proteases are involved in activation. However, because inhibition of MMPs almost completely prevented TGF-ß activation, MMPs appear crucial for activation. During culture, inclusion of the tetracycline-derived, collagenase/gelatinase inhibitor chemically modified nonantimicrobial tetracycline (CMT-8) at concentrations specific for MMP-13 inhibition resulted in complete inhibition of TGF-ß activation by proliferating and hypertrophic chondrocytes. These results show that TGF-ß production, release, and activation are regulated developmentally in chondrocytes. Our findings point to a strict mode of regulation of this potent factor to elicit diverse and highly specific effects during chondrocyte maturation and ossification

In situ localization and characterization of active proteases in chronically inflamed and healthy human gingival tissues

Background: Studies have indicated an important role for host-derived proteases in the pathogenesis of periodontal disease. The objectives of this study were: 1) to develop an assay measuring protease activity in situ and 2) to localize and characterize the enzymatic activity in intact inflamed and healthy gingiva. Methods: Gingival specimens were prepared and overlaid with a quenched fluorescent substrate. Protease activity was visualized by fluorescence microscopy and correlated with histologic features. Results: In inflamed tissues, enzymatic activity was detected mainly in the connective tissue (predominantly matrix metalloproteases) and, to some extent, in the epithelium (predominantly serine proteases). In contrast, clinically healthy tissues failed to exhibit significant amounts of protease activity. Quantitative and qualitative characteristics of protease activity in intact tissues were found to be pH dependent. Conclusions: The method described here enabled assessment of active proteases in intact tissues where cell-cell and cell-matrix interactions had been maintained. Our results indicate that there are substantial differences in the distribution of specific proteases between clinically healthy and inflamed periodontal tissues