The Development of Thermoresponsive Polymeric Simvastatin Prodrug for the Treatment of Experimental Periodontitis in Rats.

Periodontitis (PD) is a severe inflammatory gum pathology that damages the periodontal soft tissue and bone. It is highly prevalent in the US, affecting more than 47% of adults. Besides routine scaling and root planing, there are few effective treatments for PD. Developed as an effective treatment for hyperlipidemia, simvastatin (SIM) is also known for its well-established anti-inflammatory and osteogenic properties, suggesting its potential utility in treating PD. Its clinical translation, however, has been impeded by its poor water-solubility, lack of osteotropicity, and side effects (e.g., hepatoxicity) associated with systemic exposure. To address these challenges, an N-(2-hydroxypropyl) methacrylamide (HPMA) copolymer-based thermoresponsive polymeric prodrug of SIM (ProGel-SIM) was developed as a local therapy for PD. Its aqueous solution is free-flowing at 4 °C and transitions into a hydrogel at ∼30 °C, allowing for easy local application and retention. After a thorough characterization of its physicochemical properties, ProGel-SIM was administered weekly into the periodontal pocket of an experimental rat model of PD. At 3 weeks post initiation of the treatment, the animals were euthanized with palate isolated for µ-CT and histological analyses. When compared to dose equivalent simvastatin acid (SMA, active form of SIM) treatment, the rats in the ProGel-SIM treated group showed significantly higher periodontal bone volume (0.34 mm3 vs 0.20 mm3, P = 0.0161) and less neutrophil (PMN) infiltration (P < 0.0001) and IL-1ß secretion (P = 0.0036). No measurable side effect was observed. Collectively, these results suggest that ProGel-SIM may be developed as a promising drug candidate for the effective clinical treatment of PD.

Local simvastatin and inflammation during periodontal mini-flap wound healing: Exploratory results.

BACKGROUND: The objective of this exploratory study was to evaluate inflammatory markers in periodontal maintenance patients from a randomized, double-masked, parallel intervention clinical trial comparing local simvastatin (SIM) to carrier alone following mini-flap access. METHODS: Fifty patients with a 6-9-mm inflamed pocket during periodontal maintenance therapy (PMT) were treated with papilla reflection (PR)/root planing and placement of 2.2-mg simvastatin in methylcellulose (SIM/MCL) or methylcellulose alone (MCL). A small piece of interproximal soft tissue was harvested at baseline and 2 weeks postoperatively, gingival crevicular fluid (GCF) obtained at baseline, 2 weeks and 12 months, and bleeding on probing (BOP) and clinical attachment level (CAL) were measured at baseline and 12 months. Pro-inflammatory interleukin (IL)-6 and anti-inflammatory IL-10 gene activation were determined by reverse transcriptase polymerase chain reaction (rt-PCR). GCF IL-1ß, IL-6, IL-10, and vascular endothelial growth factor (VEGF-A) were measured with multiplex technology. Comparisons between groups and over time used logistic regression and general estimating equations. Associations between inflammatory markers and 12-month outcomes used Wilcoxon rank sum tests or Pearson correlations. RESULTS: Patients in the SIM group had 4.17 greater odds (p = 0.047) of improved BOP at 12 months. Median IL-6 and VEGF were significantly increased for all patients after 2 weeks of healing (p < 0.0001 and p = 0.03, respectively), while median IL-10 gene activation was increased after 2 weeks in SIM/MCL (NS). Overall, elevated GCF IL-10 at 2 weeks was significantly correlated with improved CAL at 12 months (r = -0.32, p = 0.03). CONCLUSIONS: Local SIM/MCL may have anti-inflammatory effects that potentially are associated with improved long-term CAL outcomes.

Effect of interproximal home oral hygiene on clinical parameters and inflammatory biomarkers in patients receiving periodontal maintenance.

BACKGROUND: The purpose of this 6-week, single-blinded, randomized clinical trial was to determine if the use of an interproximal brush, with or without a tracking device, is more effective than an oral irrigator in improving interproximal probing depth (PD), clinical attachment level (CAL), plaque index (PI), gingival index (GI), bleeding on probing (BOP), and inflammatory markers. METHODS: Seventy-six patients with Stages III-IV, Grade B periodontitis and a 5-7 mm posterior interproximal PD with BOP were randomized: (1) interproximal brush alone (IB; n = 26), (2) interproximal brush with tracking device (TD; n = 23), (3) oral irrigator (OI; n = 27). Participants used devices once daily for 6 weeks. Clinical measurements (PD, CAL, PI, BOP, GI) and gingival crevicular fluid (GCF) samples were collected at baseline and 6 weeks. RESULTS: All groups showed a significant reduction in PD and CAL (≥1.1 mm, p < 0.0001) and improvement in BOP (≥56%, p < 0.0001) and GI (≥82%, p < 0.001) at the experimental site with no differences among groups. The IB and IB+TD groups showed a significant reduction in PI (≥0.9, p ≤ 0.01). Interleukin (IL)-1ß was reduced in all groups (p = 0.006), but IB+TB more than OI (p ≤ 0.05). IL-10 was reduced among all groups (p = 0.01), while interferon-gamma significantly increased (p = 0.01) in all groups. CONCLUSIONS: IB and OI improved clinical parameters of PD and CAL and reduced inflammatory markers (BOP, GI, GCF IL-1ß). IB had better interproximal plaque reduction. Tracking did not significantly improve clinical parameters compared with the IB and OI groups, suggesting future modifications are needed.

Effect of locally applied simvastatin on clinical attachment level and alveolar bone in periodontal maintenance patients: A randomized clinical trial.

BACKGROUND: The purpose of this double-masked, randomized, controlled trial was to determine if the local application of simvastatin (SIM), combined with minimally invasive papilla reflection and root planing (PR/RP), is effective in improving clinical attachment level (CAL), probing depth (PD) reduction, and increasing interproximal bone height (IBH) in persistent 6-9 mm periodontal pockets in patients receiving periodontal maintenance therapy (PMT). METHODS: Fifty patients with Stage III, Grade B periodontitis presenting with a 6-9 mm interproximal PD with a history of bleeding on probing (BOP) were included in the study. Experimental [PR/RP+SIM/methylcellulose (MCL); n = 27] and control (PR/RP+MCL; n = 23) therapies were randomly assigned. Root surfaces were accessed via reflection of interproximal papillae, followed by RP assisted with endoscope evaluation, acid etching, and SIM/MCL or MCL application. CAL, PD, BOP, plaque presence, and IBH (using standardized vertical bitewing radiographs) were evaluated at baseline and 12 months. Measurements were compared by group and time using Chi-square, Wilcoxon rank-sum, and t-tests. RESULTS: Both PR/RP+SIM/MCL and PR/RP+MCL, respectively, resulted in improvements in clinical outcomes (CAL: -1.9 ± 0.3 mm, p < 0.0001; -1.0 ± 0.3 mm, p < 0.003; PD: -2.3 mm ± 0.3, p < 0.0001; -1.3 mm ± 0.3, p < 0.0001; BOP: -58.7%; -41.7%, p < 0.05) and stable IBH (-0.2 ± 0.12, -0.4 ± 0.2, p = 0.22) from baseline to 12 months post-therapy. PR/RP+SIM/MCL had more improvement in CAL (p = 0.03), PD (p = 0.007), and BOP (p = 0.047). CONCLUSIONS: The addition of SIM/MCL to PR/RP improved CAL, PD, and BOP compared with PR/RP alone in periodontal maintenance patients.

Effects of enamel matrix derivative on clinical and inflammatory outcomes in periodontal maintenance patients: Randomized controlled clinical trial.

BACKGROUND: Efficient methods to treat persistent pockets during periodontal maintenance therapy (PMT) require further investigation. The hypothesis of this randomized controlled clinical trial was that local application of enamel matrix derivative (EMD) added to papilla reflection/root preparation (PR/RP) could enhance clinical and inflammatory outcomes, primarily clinical attachment level (CAL). METHODS: Fifty PMT patients with generalized stage III-IV, grade B periodontitis presenting with a 6- to 9-mm interproximal PD were randomly allocated to (PR/RP+EMD; n = 24) and control (PR/RP+saline; n = 26) therapies by sex and smoking status. Roots were treated with reflection of interproximal papillae, root planing assisted with endoscope evaluation, and acid etching, followed by EMD or saline application. Probing depth (PD), CAL, plaque index (PI), and interproximal bone height were evaluated at baseline and 12-months post-therapy. Gingival crevicular fluid, bleeding on probing (BOP), and interleukin-1ß were tested (ELISA) at baseline, 2 weeks, and 6 and 12 months. Groups were compared over time and between groups with Wilcoxon Rank Sum and t-tests. RESULTS: Both PR/RP+ EMD and PR/RP+S resulted in significant improvements in clinical outcomes (PD and CAL, BOP) from baseline to 12 months. No significant differences were found in clinical or inflammatory outcomes between the experimental and control groups. CONCLUSIONS: The addition of EMD to PR/RP does not significantly improve clinical or inflammatory outcomes compared with PR/RP alone during periodontal maintenance therapy.

Two-Year Randomized Clinical Trial of Adjunctive Minocycline Microspheres in Periodontal Maintenance.

Purpose: The purpose of this study was to evaluate the effects of repeated scaling and root planing (SRP), with or without locally-delivered minocycline microspheres (MM) on residual pockets in patients undergoing periodontal maintenance (PMT).Methods: Patients on PMT were randomized into two groups for treatment of one posterior interproximal inflamed pocket (≥5 mm) with a history of bleeding on probing every 6 months: SRP plus MM (n=30) or exclusively SRP (n=30). Baseline and 24-month measurements included radiographic interproximal alveolar bone height, probing depths (PD), clinical attachment level (CAL), bleeding on probing (BOP), gingival crevicular fluid (GCF), and salivary interleukin (IL) - 1ß, (24 month only). Results were analyzed for baseline data or change in measurements after 24 months of treatment between different treatment groups, as well as whether significant changes occurred after 24 months of treatment for each treatment group individually.Results: Alveolar bone height and GCF IL-1ß remained stable over the 24 months. The SRP + MM and SRP groups each demonstrated reduced PD (0.8 ± 0.9 mm and 1.1 ±0.6 mm, respectively, p < 0.001 each), CAL (0.8 ± 0.9 mm and 1.0 ± 0.6 mm, respectively, p < 0.001 each) and BOP (55% and 48%, respectively, p = 0.001 each). However, there were no differences between groups over the 24-month study period.Conclusion: Scaling and root planning alone, of moderately inflamed periodontal pockets at 6-month intervals, produced stable interproximal alveolar bone height as well as sustained improvements in probing depths, clinical attachment level, bleeding on probing over 24 months; minocycline microspheres were not shown to enhance these results.

Local Minocycline Effect on Inflammation and Clinical Attachment During Periodontal Maintenance: Randomized Clinical Trial.

BACKGROUND: Minocycline microspheres (MMs) are being used to treat residual inflamed periodontal pockets during periodontal maintenance therapy (PMT), but evidence for efficacy from randomized clinical trials is lacking. The purpose of this study is to evaluate the effect of MMs plus scaling and root planing (SRP) on these sites. METHODS: Sixty patients with chronic periodontitis on 6-month PMT intervals to be followed for 1 year were randomized (51 completed the study) into two statistically similar groups, SRP + MM (aged 66.8 years) and SRP alone (aged 67 years), to treat a ≥5 mm posterior interproximal pocket during PMT with a history of bleeding on probing (BOP). Group treatments were applied to the site at baseline and 6 months. Clinical attachment levels (CALs; primary outcome), probing depths (PDs), plaque, and BOP also were recorded at baseline and 6 and 12 months. In addition, gingival crevicular fluid was analyzed for an inflammation index ratio of interleukin (IL)-1ß/IL-1 receptor antagonist (ra) using enzyme-linked immunosorbent assays. RESULTS: All clinical parameters improved significantly (P <0.005) from baseline in both groups with no differences between groups at any time point. CAL decreased 17% (0.9 ± 0.8 mm) and 13% (0.7 ± 0.9 mm) in SRP + MM and 11% (0.7 ± 1.1 mm) and 21% (1.2 ± 0.9 mm) in SRP at 6 and 12 months, respectively. The odds of having BOP decreased 90% (down to 38% of patients) and 95% (26%) in SRP + MM and 82% (42%) and 82% (41%) in SRP at 6 and 12 months, respectively. IL-1ß/IL-1ra decreased a significant 61% (P = 0.009) only in SRP + MM at 6 months. CONCLUSIONS: SRP of inflamed moderate pockets during 6-month PMT, with or without MMs, improves CALs, along with PDs and BOP over a 1-year period. The use of MMs did not result in an additional benefit over SRP alone.

Do Mobility and Occlusal Trauma Impact Periodontal Longevity?

The impact of tooth mobility and occlusal trauma (OT) on periodontal bone loss and need for therapy has been debated for many years. This paper summarizes the relevant literature reported in three Dental Clinics of North America articles in the late 1990s, and adds newer information from the 2000s. Principle findings indicate that strong evidence of mobility and OT impacting tooth longevity is lacking, but reducing inflammation in the surrounding periodontium remains a critical treatment. Occlusal therapy when mobility is increasing, comfort or function are compromised, or periodontal regeneration procedures are planned should be considered.

Impact of local and systemic alendronate on simvastatin-induced new bone around periodontal defects.

BACKGROUND: Simvastatin has been shown to stimulate new bone growth on rat mandibles, but much of the bone is lost over time. The purpose of this study is to evaluate the impact of a locally or systemically applied antiresorptive agent (alendronate) on simvastatin-induced bone formation in and adjacent to a rat periodontal defect. METHODS: Fenestration defects were created over mandibular molar roots in 65 mature female Sprague-Dawley rats. Two weeks later, animals were divided into eight groups of eight to nine rats, and three weekly injections around the defect were applied: 1) 0.5 mg simvastatin in ethanol (SIM-EtOH); 2) 0.5 mg simvastatin in alendronate-cyclodextrin conjugate (SIM-ALN-CD); 3) EtOH alone; 4) ALN-CD alone; or 5) no injections. Twenty-four animals were evaluated for new bone width around the defect 21 days after the last injections (short-term) and 41 rats were followed for 48 days (long-term). Three SIM-EtOH groups of long-term rats also were subjected to 2 weeks of daily systemic ALN or saline either during or 3 to 4 weeks after SIM-EtOH injections. Decalcified, hematoxylin-and-eosin-stained cross-sections of the defect area were analyzed for new bone width and groups were compared using mixed-model analyses of variance. RESULTS: All groups showed nearly 100% bone fill, with no differences among the short-term groups. However, in the long-term animals, two-fold to three-fold more new bone width (≤ 0.004) was seen around the periphery of the defect with the use of systemic ALN after SIM-EtOH injections (0.93 ± 0.12 and 0.78 ± 0.11 mm with early and late systemic ALN, respectively) compared to local SIM/ALN-CD preparations (0.32 ± 0.10 mm) or short-term SIM-EtOH injections (0.35 ± 0.10 mm). No significant new cementum formation or ankylosis was noted. CONCLUSION: The use of a short course of systemic ALN during the healing period after bone anabolic SIM injections has the potential to enhance local bone augmentation.

Simvastatin application to augment facial jaw bone in a dog model: pilot study.

BACKGROUND: Locally injected simvastatin (SIM) has been shown to induce bone growth in rat models. The purpose of this study is to evaluate the effects of locally injected simvastatin in several human-like clinical situations in a beagle dog model. METHODS: Four beagle dogs completed the study and were used in a split-mouth design. Dehiscence defects of 5 × 3 mm were created bilaterally on the lateral aspect of the mandibular second premolar (PM2) mesial roots including removal of root cementum. At the same surgery, porous hydroxyapatite-collagen grafts with resorbable membranes with or without 10-mg SIM were placed buccal to the mandibular first molars (M1). One week later, three weekly local injections of 10-mg SIM in ethanol and contralateral ethanol alone were initiated at three sites through the buccal mucosa: 1) 6 mm apical to the cemento-enamel junction (CEJ) of the maxillary fourth premolar (PM4; thin bone over root); 2) 6 mm apical to the CEJ of PM2 (dehiscence defect); and 3) 10 mm distoapical to the CEJ of the maxillary canine (edentulous ridge). Dogs were euthanized 2 months after the final injections. Block sections were harvested and specimens were decalcified and stained with hematoxylin and eosin. Histomorphometry was performed using digitized photographs and analyzed with distribution-free rank tests. RESULTS: Regarding M1, the distance between CEJ and the alveolar crest was significantly more coronal in the SIM group (P = 0.038). Regarding the edentulous ridge, the width of new bone was significantly greater in SIM injection specimens (P = 0.0164). Regarding PM2, buccal bone in the dehiscence defects lacking periosteum was not augmented in the SIM group. Regarding PM4, the total width of bone 5 mm apical to the coronal height of contour (thin buccal bone covering the root) was significantly wider on the SIM side (SIM, 0.63 ± 0.53 mm; contralateral ethanol alone, 0.25 ± 0.19 mm; P = 0.0098). CONCLUSION: Locally injected SIM has the ability to induce modest amounts of new bone formation in closed injection sites over a periosteal surface.