Enzyme-Responsive Nanoparticles for Dexamethasone Targeted Delivery to Treat Inflammation in Diabetes.

Diabetes is a global epidemic accompanied by impaired wound healing and increased risk of persistent infections and resistance to standard treatments. Therefore, there is an immense need to develop novel methods to specifically target therapeutics to affected tissues and improve treatment efficacy. This study aims to use enzyme-responsive nanoparticles for the targeted delivery of an anti-inflammatory drug, dexamethasone, to treat inflammation in diabetes. These nanoparticles are assembled from fluorescently-labeled, dexamethasone-loaded peptide-polymer amphiphiles. The nanoparticles are injected in vivo, adjacent to labeled collagen membranes sub-periosteally implanted on the calvaria of diabetic rats. Following their implantation, collagen membrane resorption is linked to inflammation, especially in hyperglycemic individuals. The nanoparticles show strong and prolonged accumulation in inflamed tissue after undergoing a morphological switch into microscale aggregates. Significantly higher remaining collagen membrane area and less inflammatory cell infiltration are observed in responsive nanoparticles-treated rats, compared to control groups injected with free dexamethasone and non-responsive nanoparticles. These factors indicate improved therapeutic efficacy in inflammation reduction. These results demonstrate the potential use of enzyme-responsive nanoparticles as targeted delivery vehicles for the treatment of diabetic and other inflammatory wounds.

Radiographic signs of excessive occlusal forces are associated with marginal bone loss: a retrospective clinical study.

OBJECTIVES: Work in animal models has implicated excessive occlusal forces and occlusal trauma as co-destructive factors for periodontitis. The main aim of the present study was to make a radiographic assessment of the effects of excessive occlusal forces, ie occlusal/incisal tooth wear, widening of the periodontal space, and the presence of a mandibular torus, on interproximal marginal bone loss in a large series of patients. A secondary aim was to evaluate the statistical correlation between the parameters in two specific teeth and those of 12 teeth for marginal bone loss and six teeth for occlusal/incisal tooth wear within the same individual. METHOD AND MATERIALS: A total of 1,950 full-mouth radiographic surveys were analyzed retrospectively. Interproximal marginal bone loss was quantified relative to the root length (Schei ruler technique). In addition, occlusal/incisal tooth wear and periodontal ligament space widening of the periodontal space were assessed, as well as the presence of a mandibular torus. Odds ratio and logistic regression analysis were used to determine the association between occlusal trauma and marginal bone loss. RESULTS: The correlation of the measured parameters between the values for specific teeth and the whole dentition was evaluated from data from the first 400 radiographs. Teeth 41 and 33 showed the best correlation to the whole dentition: 0.85 for interproximal marginal bone loss, 0.83 for widening of the periodontal space, and 0.97 for occlusal/incisal tooth wear. The results of a logistic regression analysis with age as an independent variable, revealed a significant association between bone loss and both tooth wear (odds ratio = 2.767) and bone loss and widening of the periodontal space (odds ratio = 2.585). CONCLUSION: Tooth wear was positively correlated to both widening of the periodontal space and marginal bone loss. No correlation was found between the presence of a mandibular torus and marginal bone loss.

Addition of Resolvins D1 or E1 to Collagen Membranes Mitigates Their Resorption in Diabetic Rats.

Uncontrolled diabetes is characterized by aberrant inflammatory reactions and increased collagenolysis. We have reported that it accelerates the degradation of implanted collagen membranes (CM), thus compromising their function in regenerative procedures. In recent years, a group of physiological anti-inflammatory agents called specialized pro-resolving lipid mediators (SPMs) have been tested as a treatment for various inflammatory conditions, either systemically or locally, via medical devices. Yet, no study has tested their effect on the fate of the biodegradable material itself. Here, we measured the in vitro release over time of 100 or 800 ng resolvin D1 (RvD1) incorporated into CM discs. In vivo, diabetes was induced in rats with streptozotocin, while buffer-injected (normoglycemic) rats served as controls. Resolvins (100 or 800 ng of RvD1 or RvE1) were added to biotin-labeled CM discs, which were implanted sub-periosteally over the calvaria of rats. Membrane thickness, density, and uniformity were determined by quantitative histology after 3 weeks. In vitro, significant amounts of RvD1 were released over 1-8 days, depending on the amount loaded. In vivo, CMs from diabetic animals were thinner, more porous, and more variable in thickness and density. The addition of RvD1 or RvE1 improved their regularity, increased their density, and reduced their invasion by the host tissue significantly. We conclude that addition of resolvins to biodegradable medical devices can protect them from excessive degradation in systemic conditions characterized by high degree of collagenolysis.

Single-cell transcriptomic analysis of oral masticatory and lining mucosa-derived mesenchymal stromal cells.

AIM: To reveal the heterogeneity of ex vivo-cultured human mesenchymal stromal cells derived from either masticatory or lining oral mucosa. MATERIALS AND METHODS: Cells were retrieved from the lamina propria of the hard palate and alveolar mucosa of three individuals. The analysis of transcriptomic-level differences was accomplished using single-cell RNA sequencing. RESULTS: Cluster analysis clearly distinguished between cells from the masticatory and lining oral mucosa, and revealed 11 distinct cell sub-populations, annotated as fibroblasts, smooth muscle cells or mesenchymal stem cells. Interestingly, cells presenting a mesenchymal stem cell-like gene expression pattern were predominantly found in masticatory mucosa. Although cells of masticatory mucosa origin were highly enriched for biological processes associated with wound healing, those from the lining oral mucosa were highly enriched for biological processes associated with the regulation of epithelial cells. CONCLUSIONS: Our previous work had shown that cells from the lining and masticatory oral mucosae are phenotypically heterogeneous. Here, we extend these findings to show that these changes are not the result of differences in averages but rather represent two distinct cell populations, with mesenchymal stem cells more common in masticatory mucosa. These features may contribute to specific physiological functions and have relevance for potential therapeutic interventions.

Radiographic protrusion of dental implants in the maxillary sinus and nasal fossae: A multidisciplinary consensus utilising the modified Delphi method.

The aim of the present study was to generate an international and multidisciplinary consensus on the clinical management of implant protrusion into the maxillary sinuses and nasal fossae. A total of 31 experts participated, 23 of whom were experts in implantology (periodontologists, maxillofacial surgeons and implantologists), 6 were otolaryngologists and 2 were radiologists. All the participants were informed of the current scientific knowledge on the topic based on a systematic search of the literature. A list of statements was created and divided into three surveys: one for all participants, one for implant providers and radiologists and one for otolaryngologists and radiologists. A consensus was reached on 15 out of 17 statements. According to the participants, osseointegrated implants protruding radiographically into the maxillary sinus or nasal fossae require as much monitoring and maintenance as implants fully covered by bone. In the event of symptoms of sinusitis, collaboration between implant providers and otolaryngologists is required. Implant removal should be considered only after pharmacological and surgical management of sinusitis have failed.

On the Association between Implant-Supported Prosthesis and Glycemic Control (HbA1c Values).

Background: Dietary habits, food intake and oral health are important factors for general health. The aim of these present study was to assess the association between implant-supported fixed oral rehabilitation and glycemia, by monitoring HbA1c values before and after implant-supported prostheses (ISP) delivery to diabetic individuals. Methods: Retrospective, cohort study based on dental records. All treatments were performed by experienced oral and maxillofacial surgeons and experienced prosthodontists. Inclusion criteria: ISP delivery, diagnosis of diabetes in the medical files, consecutive individuals. Variables included­primary outcome­differences (delta) in HbA1c values prior to implant placement and one year after ISP delivery, early implant failure (EIF). Confounding factors included age, gender, physical status, smoking, implant jaw location, implant length, implant width, total implant count per individual. Results: Statistically significant (p < 0.01) decrease in HbA1c from 7.10 ± 1.09% to 6.66 ± 1.02% following ISP delivery was recorded. The mean HbA1c delta was 0.44 ± 0.73%, where 39.0% of the patients had a significant improvement (delta decrease > 0.5%). Univariate and multivariate model using logistic regression at individual level showed that initial high HbA1c levels was the only factor positively predicting improvement (OR = 1.96, CI [1.22, 3.14], p < 0.01). Univariate model at implant level demonstrated that implants placed in the anterior maxilla also contributed to significant improvement in HbA1c values. Multivariate analysis at implant level was similar to individual level. Number of missing teeth did not affect the results significantly. Conclusion: ISP delivery to partially or completely edentulous diabetic individuals may improve HbA1c balance. The mechanism awaits future elucidation.

Oral and Dental Considerations of Combat-Induced Post Traumatic Stress Disorder (PTSD)-A Cross-Sectional Study.

Objective: This study compared dental, periodontal, oral, and joint/muscle tenderness among Israeli combat-induced post-traumatic stress disorder (Ci-PTSD) war veterans to non-PTSD patients. Study design: This retrospective three-arm study compared oral and facial manifestations between 100 Israeli veterans with Ci- PTSD (study group) and 103 non-PTSD periodontal patients (Control group). The study group was further divided into two subgroups of individuals who received psychiatric medications (40 patients) or did not (60 patients). All patients underwent complete dental, oral, and periodontal examinations, including assessing signs of parafunction. Results: All PTSD patients had poor oral hygiene. The plaque index (PI) was higher in the PTSD group compared to the control group (0.72 ± 0.28 vs. 0.45 ± 0.29, respectively, p < 0.001). The decayed, missing, and filled teeth score (DMFt) was higher in the PTSD population than in the controls (19.97 ± 8.07 vs. 13.05 ± 6.23 p < 0.05). Severe periodontal disease was more common among the PTSD subgroup taking medications (med -group) (62.5%) compared to the nonmedicated group (non-med group) (30.0%) and the controls (27.2%) (p = 0.001). Heavy smoking was more prevalent in the medicated PTSD patients than in other groups. Conclusions: The present study shows higher morbidities in combat-induced PTSD patients, including oral, dental, and periodontal manifestations, especially in medicated patients.

Histologic and Histomorphometric Evaluation of a Connective Tissue Graft Retrieved with a Novel Deepithelialization Procedure: A Case Series.

Various free connective tissue graft (CTG) harvesting techniques have been reported. The lining epithelium of the palatal graft may be retrieved either intra- or extraorally. This report presents a series of root coverage cases where deepithelialization was intraorally performed before harvesting the graft with a round diamond bur mounted on a low-speed handpiece. Ten single-tooth gingival recession defects in five patients were treated, applying a surgical procedure based on a coronally advanced flap combined with a free CTG that was deepithelialized in situ by the same method. Recession and probing depths and keratinized tissue and recession widths were recorded at baseline and the follow-up evaluations. Follow-up was between 7 and 21 months (mean: 12.1 ± 5.04 months). Clinical, esthetic, and histologic evaluations were performed. Mean root coverage was 89% ± 24.86% (range: 25% to 100%), and complete root coverage was observed in 80% of cases; the esthetic score range was 6 to 9 (mean: 7.44 ± 1.01). Epithelial remnants, although different in proportions, were evident in all samples (range of prevalence: 4.57% to 29.12%). Within the limitations of the small number of clinical cases, the presented in situ deepithelialization technique for CTG seems to be valuable and may accordingly be routinely applied.

Cross-linked hyaluronic acid slows down collagen membrane resorption in diabetic rats through reducing the number of macrophages.

OBJECTIVES: We previously showed that accelerated degradation of collagen membranes (CMs) in diabetic rats is associated with increased infiltration of macrophages and blood vessels. Since pre-implantation immersion of CMs in cross-linked high molecular weight hyaluronic acid (CLHA) delays membrane degradation, we evaluated here its effect on the number of macrophages and endothelial cells (ECs) within the CM as a possible mechanism for inhibition of CM resorption. MATERIALS AND METHODS: Diabetes was induced with streptozotocin in 16 rats, while 16 healthy rats served as control. CM discs were labeled with biotin, soaked in CLHA or PBS, and implanted under the scalp. Fourteen days later, CMs were embedded in paraffin and the number of macrophages and ECs within the CMs was determined using antibodies against CD68 and transglutaminase II, respectively. RESULTS: Diabetes increased the number of macrophages and ECs within the CMs (∼2.5-fold and fourfold, respectively). Immersion of CMs in CLHA statistically significantly reduced the number of macrophages (p < 0.0001) in diabetic rats, but not that of ECs. In the healthy group, CLHA had no significant effect on the number of either cells. Higher residual collagen area and membrane thickness in CLHA-treated CMs in diabetic animals were significantly correlated with reduced number of macrophages but not ECs. CONCLUSIONS: Immersion of CM in CLHA inhibits macrophage infiltration and reduces CM degradation in diabetic animals. CLINICAL RELEVANCE: The combination of CLHA and CM may represent a valuable approach when guided tissue regeneration or guided bone regeneration procedures are performed in diabetic patients.

Fibroblasts from the oral masticatory and lining mucosa have different gene expression profiles and proliferation rates.

AIMS: To compare the gene expression profiles and proliferation rates of fibroblasts from the oral lining and masticatory mucosae. MATERIALS AND METHODS: Primary human fibroblasts were retrieved from the posterior masticatory hard palate and the lining alveolar mucosa of five individuals. The gene expression profile was evaluated using total RNA sequencing. The proliferation rate was determined colorimetrically. RESULTS: Substantial differences in specific gene groups and pathways were observed between fibroblasts from the two tissues. Significantly enriched gene ontology processes were focused on the extracellular components. Lining mucosa fibroblasts exhibited significantly higher expression of the principal structural collagens, cranial neural crest markers, and homeobox genes associated with positional memory. Masticatory mucosa fibroblasts showed greater expression of genes related to transforming growth factor-ß signalling, which may be associated with fibrosis. In addition, they expressed higher levels of the EP2 prostaglandin E2 receptor and Toll-like receptor 1. Finally, masticatory mucosa fibroblasts exhibited a 10%-30% higher proliferation rate. CONCLUSIONS: Fibroblasts from the lining and masticatory oral mucosae are phenotypically heterogeneous, presenting distinct gene expression profiles and proliferation rates. These features may contribute to their specific physiological functions and have relevance for potential therapeutic applications.

Comparative Study of Deproteinized Bovine Bone Mineral and Bovine Bone Mineral Enriched with a Polymer and Gelatin in Maxillary Sinus Floor Elevation Procedures.

The aim of this histomorphometric study was to compare the outcome of sinus floor augmentation procedures using bovine bone mineral and a xenograft enriched with gelatin and a polymer. In 20 patients a single sinus floor elevation procedure with a lateral window approach was performed. In half of the patients, sinuses were grafted with a deproteinized bovine bone mineral-DBBM (control group)-while in the remaining 10, a xenograft enriched by polymer and gelatin-NBS (test group)-was applied. In the DBBM group, histomorphometric analysis revealed 23.14 ± 10.62% of lamellar bone, 19.43% ± 9.18% of woven bone, 23.35% ± 6.04% of osteoid, 17.16% ± 6.13% of biomaterial particles, and 16.93% ± 9.78% of medullary spaces. In the NBS group, histomorphometric analysis found 39.64% ± 12.02% of lamellar bone, 16.28% ± 7.75% of woven bone, 17.51% ± 4.87% of osteoid, 12.72% ± 5.36% of biomaterial particles, and 13.84% ± 6.53% of medullary spaces. Differences between groups for proportion of lamellar bone (P = .004) and osteoid (P = .0287) were statistically significant. Inflammatory infiltration was appreciated only in the NBS group. The enriched xenograft showed a statistically significant higher proportion of lamellar bone and osteoid; however, this was accompanied by an accentuated inflammatory infiltrate.

The Incidence and Nature of Claims against Dentists Related to Periodontal Treatment in Israel during the Years 2005-2019.

BACKGROUND: In recent years, worldwide dental malpractice claims have dramatically increased. The purpose of the present study is to analyze periodontal therapy related claims in Israel that led to legal decisions. METHODS: This retrospective cohort study includes malpractice claims against dental practitioners related to periodontology between 2005 and 2019. Only closed cases where a final decision was made were included. The chi-square test or Fisher exact test for categorical variables were performed and a p value of <0.05 was considered statistically significant. RESULTS: During the study period there were 508 legal claims related to periodontal disease. Most plaintiffs were women (63.4%), and 71.3% of the patients were >35 years old. Most claims (82.8%) were settled out of court and ended in compromise. Claims concerning the treatment of periodontal disease by periodontists accounted only for 4.5% (23/508) of the cases while 95.5% (485/508) of the claims were for complications secondary to another treatment. Prosthodontic treatment was involved with the highest number 54.5%, followed by dental implants 17.7%, and endodontics 11.6%. The allegations were related to pain and distress (84.8%), aggravation of existent periodontal disease (83.3%), tooth loss (78.1%), and violation of autonomy (47%). CONCLUSIONS: The main cause for lawsuits was related to aggravation of periodontal disease during prosthetic or implant therapy and related to suspected faulty or inexistent preoperative diagnosis and planning. PRACTICAL IMPLICATIONS: Periodontal consultation before dental treatment may reduce malpractice risks, adverse events, and un-necessary changes of treatment plans.

Effect of root surface conditioning on gingival recession coverage with a connective tissue graft. A retrospective comparative study of three different agents.

OBJECTIVE: Different root modifiers have been proposed in the literature with an attempt to improve the healing process and the success rate of root coverage procedures. The aim of the present retrospective study was to evaluate the effect of three different types of root surface conditioning, namely, tetracycline (TTC), ethylene-di-amino-tetra-acetic acid (EDTA) and saline, on the outcome of root coverage procedures applying the same surgical technique. MATERIALS AND METHODS: Twenty-nine patients with 60 Classes I, II, or III recession defects were treated using connective tissue with a partial-thickness double-pedicle graft. In 21 recession defects root surface was treated with TTC and, in other 21, with EDTA, while in the remaining, saline solution was applied. Statistical analysis consisted of descriptive statistics and Kruskal-Wallis, Mann-Whitney, and chi-square tests. RESULTS: Differences between pre- and postoperative values were statistically significant only within but not between groups. Mean root coverage was 73.25%, 69.19%, and 82.17% in the TTC, the EDTA, and the saline groups, respectively. The study revealed no statistically significant differences for all evaluated parameters between groups. CONCLUSION: Within the limits of this study, root conditioning, prior to root coverage procedures, does not significantly affect their outcome. CLINICAL SIGNIFICANCE: Clinical outcome of root coverage procedures is not related to the type of root surface conditioning.

The Influence of Residual Alveolar Bone Height on Graft Composition after Maxillary Sinus Augmentation Using Two Different Xenografts: A Histomorphometric Comparative Study.

AIM: To evaluate the hypothesis of a correlation between the preoperative residual alveolar bone height (RBH) and graft maturation after maxillary sinus floor augmentation procedures using two different bone substitutes. METHODS: A total of 20 patients who underwent unilateral maxillary sinus floor augmentation with either mineralized deproteinized bovine bone (DBBM) or a xenograft enriched with polymer and gelatin (NBS) were included in this prospective study. Six months after sinus surgery, bone biopsies were harvested with a 3.2 mm diameter trephine bur, prior to dental implant placement. Histomorphometric analysis was performed, and the results were correlated with the individual RBH. Implants were loaded after 5 months of insertion, and 1-year implant success and marginal bone level change were assessed. RESULTS: RBH was 2.17 ± 1.11 mm (range 0.5-3.5 mm) and 2.14 ± 0.72 mm (range 0.5-3.0 mm) in the NBS and DBBM group, respectively. The biopsy analyses for the DBBM group showed woven bone increases by 5.08% per 1-mm increment of RBH; medullary spaces decreased by 9.02%, osteoid decreased by 4.4%, residual biomaterial decreased by 0.34%, and lamellar bone increased by 5.68% per 1-mm increase of RBH. In the NBS group, samples showed woven bone increases by 8.08% per 1-mm increase of RBH; medullary spaces decreased by 0.38%; osteoid increased by 1.34%, residual biomaterial decreased by 0.58%, and lamellar bone decreased by 5.50% per 1-mm increase of RBH. There was no statistically significant difference in the correlation between RBH and lamellar bone, woven bone, and osteoid, independently of the material used. Implant success was 100% in both groups, and marginal bone loss was 1.02 ± 0.42 mm in DBBM and 0.95 ± 0.31 mm in the NBS group after the 1-year follow-up. CONCLUSION: In spite of the absence of significance, the observed trend for woven bone to increase and medullary spaces to decrease when RBH increases deserves attention. Residual bone dimension might be a determinant in the bone graft maturation after maxillary sinus augmentation.

Oral and dental considerations of combat-induced PTSD: a descriptive study.

OBJECTIVE: Stress experienced as an intense and traumatic event can increase the odds of orofacial morbidities that may affect oral, periodontal, or masticatory system health. The aim of this study was to evaluate the dental, periodontal, oral, and bruxism situation among Israeli posttraumatic stress disorder (PTSD) war veterans. METHOD AND MATERIALS: This retrospective cohort pilot study aimed to examine the oral and facial manifestations in 71 Israeli veterans with combat PTSD. All patients underwent full dental, oral, and periodontal examination. Signs of parafunctional activity were also evaluated, accompanied by a full set of periapical and/or panoramic radiographs. RESULTS: The patients were 37 to 77 (mean 60.7 ± 10.15) years of age and presented a poor overall oral hygiene status (Plaque Index 0.75 ± 0.26). All patients (100.0%) suffered from periodontal disease, and most of them (66.0%) were severely affected. A significant correlation was found between signs of parafunctional activity and severe periodontal disease (P = .035). The patients had a high decayed, missing, and filled teeth (DMFT) score (20.06 ± 8.86), which was mainly attributed to the large number of "filled" (F) teeth (11.95 out of 20.06). The DMFT score was significantly lower among light smokers than among heavy, former, or nonsmokers (P = .012). Most patients (90%) had signs and symptoms of parafunctional activities. A significant positive and dose-dependent correlation was found between smoking and periodontal disease (P = .012). CONCLUSIONS: An association was found between combat PTSD and oral, dental, and periodontal morbidity.

Dental implant placement is a possible risk factor for the development of multiple cracks in non-endodontically treated teeth.

The objective of this study was to evaluate potential risk factors, including the placement of dental implants, for the development of tooth cracks. A series of 212-patients, who were referred for endodontic treatment, were retrospectively screened, of which 72 (34%) patients had been diagnosed with 80-cracked teeth confirmed with an operating microscope. These patients had an average age of 53-years and were equally distributed between genders. Forty-one percent of the cracked teeth were diagnosed after the placement of dental implants, with an average of 3-implants per patient. Seventy percent of the cracks were diagnosed more than 1-year after implant loading. Implant placement was associated with higher odds of having multiple cracks (OR = 9.78, CI:2.320, 41.216)(p < 0.05). The proportion of cracked premolars was relatively high (30%), and most cracked teeth (79%) were vital and with a normal periapical diagnosis (86%). Most cracked teeth (71%) had an amalgam restoration, and teeth restored with amalgam were at a higher risk of having multiple cracks (p < 0.05). Clinicians should be aware of a common profile of endodontic patients with multiple cracks in a non-endodontically treated premolar, restored with an amalgam restoration, which was diagnosed with the cracks more than 1-year after reconstruction utilizing multiple implants.

Porphyromonas gingivalis lipopolysaccharide and glycated serum albumin increase the production of several pro-inflammatory molecules in human gingival fibroblasts via NFκB.

OBJECTIVE: Diabetes increases the incidence/severity of periodontal diseases by inducing a chronic inflammation, driven by accumulation of AGEs (advanced glycation end products). We tested whether glycated human serum albumin (G-HSA, a form of AGE), representing a diabetic state, augments the pro-inflammatory response of human gingival fibroblasts (hGFs) to a bacterial challenge (Porphyromonas gingivalis Lipopolysaccharide (LPS)). METHODS: Primary hGFs were incubated with LPS (0.5-5 µg/mL) and G-HSA (50-200 µg/mL) and the production and gene expression of IL-1ß, IL-6, IL-8, MMP-1, MCP-1, and TNFα were analyzed by Magnetic Luminex Assay and real-time PCR, respectively. Non-glycated serum albumin (HSA) served as negative control. Cytotoxicity of the 2 agents was tested with an XTT assay. NFκB activation (p65 phosphorylation) was measured with an ELISA. RESULTS: P. gingivalis LPS and G-HSA were not toxic to hGFs and increased the amount of MMP-1, MCP-1, IL-6, and IL-8, (but not TNFα and IL-1ß) secreted into the medium at 24 h. Control HSA had no effect. Many LPS/G-HSA combinations displayed a synergistic stimulation of these molecules. Both agents increased mRNA levels of these 4 molecules at 6 h, 12 h or both (IL-6). NFκB activation at 6 h was caused by both agents with a possible synergism at the higher concentrations. CONCLUSIONS: glycated albumin augments the pro-inflammatory response of human gingival fibroblasts to P. gingivalis LPS. Thus, AGE accumulation in diabetes could aggravate periodontal inflammation by augmenting the pro-inflammatory response of host GFs to P. gingivalis, a well-recognized periopathogenic bacteria.

Accelerated degradation of collagen membranes in type 1 diabetic rats is associated with increased expression and production of several inflammatory molecules.

BACKGROUND: Membrane durability is critical for regenerative procedures. We reported previously that type 1-like diabetes in rats accelerates the degradation of collagen membranes and we tested here whether this is associated with increased local production of inflammatory molecules as part of a diabetes-induced chronic inflammation around and within the membranes. METHODS: Collagen membrane discs were implanted under the scalp in diabetic (streptozotocin-induced) and control rats, which were sacrificed after 2 or 3 weeks. Total RNA and proteins were isolated from the membrane and its surrounding tissues and the expression and production of six inflammatory molecules (interleukin-6 [IL-6], tumor necrosis factor alpha [TNFα], matrix metalloproteinase [MMP]-9, macrophage migration inhibitory factor [MIF], MIP-1α, and MIP-2α) was measured using real-time PCR and western blotting, respectively. Minimal histological analysis of the membranes was conducted to conform to previous studies. RESULTS: Hyperglycemia resulted in reduced membrane thickness (by 10% to 25%) and increased mononuclear infiltrate inside the membrane. mRNA and protein levels of IL-6, TNFα, and MMP-9 were elevated in diabetic rats both 2 and 3 weeks post-surgery. The levels (both mRNA and protein) of MIF were increased at 2 weeks post-surgery and those of MIP-1α and MIP-2α at 3 weeks. There was a very good match in the temporal changes of all examined genes between the mRNA and protein levels. CONCLUSIONS: Elevated local production of inflammatory cytokines and MMPs, together with apparent mononuclear infiltrate and increased collagenolysis confirm that hyperglycemia leads to a chronic inflammation in and around the implanted collagen membranes, which reduces membrane longevity.

Hyaluronic acid slows down collagen membrane degradation in uncontrolled diabetic rats.

AIM: To examine the in vitro biokinetics of hyaluronic acid (HA) from a collagen membrane (CM) and to evaluate the in vivo effect of immersion of the CM in HA solution on its degradation in streptozotocin (STZ)-induced diabetes conditions in a rat calvaria subcutaneous model. BACKGROUND: CM degradation is accelerated in uncontrolled diabetic rats. Immersion of CM in HA has been suggested to decrease their resorption rate without interfering with their tissue integration and structural degradation. However, it is unknown to what extent CM degradation may be influenced by its immersion in HA solution under a condition mimicking a medically compromised situation with an increased inflammatory level such as diabetes. MATERIALS AND METHODS: CMs were soaked in cross-linked HA. Protein adsorption and the HA release were quantified by ELISA. Diabetes was induced in sixteen rats, while 16 healthy rats served as control. CM was prepared and labeled prior to implantation with Biotin. Seventeen CM were immersed in HA and 17 CM in PBS. In each animal, one test or one control disk was implanted. In order to compare the collagen content, two similar non-implanted CM were used as baseline. Fourteen days after surgery, thirty-two animals were sacrificed. The entire calvaria including the skin above, was chemically fixed, decalcified, and embedded in paraffin. Five-µm-thick sections were analyzed histologically and histomorphometrically using H&E and avidin-peroxidase staining. RESULTS: The in vitro results demonstrated that the CM adsorbed roughly 80% of the total HA content. After 10 days, 36.3% of the initial HA remained on the CM. The in vivo results demonstrated that diabetes significantly reduced the thickness of the CM, while HA had a significant effect on keeping the membrane thickness. HA increased the residual collagen content in the diabetic group (P < 0.0001) but no such effect was observed in the healthy group. CONCLUSION: Immersion of CM in HA prior to the implantation delays membrane degradation in uncontrolled diabetic compared with normoglycemic rats.

Modified Tunnel Double Papilla Procedure for Root Coverage in the Anterior Mandible.

Free connective tissue grafts, barrier membranes, pedicle flaps, soft tissue allografts, and xenografts have been described for root coverage and augmenting the zone of attached gingiva. The present report evaluated a modified tunnel surgical procedure for root coverage of mandibular anterior teeth where a connective tissue graft was combined with a tunnel and double papilla flap. Fourteen patients with 18 consecutive Miller Class I or II gingival recession defects in the anterior mandible were treated with a connective tissue graft combined with a tunnel and double papilla flap procedure. The following parameters were recorded at baseline and every 6 months postsurgery for up to 19 months: probing depth (PD), vertical recession dimension (RD), keratinized tissue width (KT), and recession width (RW). Statistical analysis consisted of descriptive statistics, analysis of variance with repeated measures, and t test. Statistical analysis proved significant differences between pre- and postoperative values. Mean percentage of root coverage was 83.28% (standard deviation: 22.897), while complete root coverage was obtained in 55% of sites. Baseline values differed between Class I and II recession defects. Clinical attachment level gain, KT gain, and amount of root coverage were statistically significantly larger in Class II defects, while the degree of residual recession and percentage of root coverage were similar in both recession classes. A statistically significant interaction between recession class, independent variable, and pre- and postoperative vertical recession defects (dependent variables) was recorded (P = .004). Within the limitations of the sample size, the reported procedure showed predictable root coverage with color match combined with an increased zone of keratinized tissue.