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.

Bioactivated Implant Surfaces Placed in Healed Sites or Extraction Sockets: A Preliminary Experimental Study in Dogs.

PURPOSE: To monitor the early bone reaction in a canine model to a conventional sandblasted and dual acid-etched implant surface (ABT), a nanostructured hydrophilic surface (Nano), a dry salt-bioactivated ultra-hydrophilic surface (Hydro), and a bioactivated nanosurface obtained from the addition of dry salts to the Nano surface (Nano-Active). MATERIALS AND METHODS: ABT, Nano, Hydro, and Nano-Active implants were placed in 12 dogs. A randomized split-mouth design was adopted. One implant of each type was placed in the mandible 3 months after tooth extraction in healed sites at the first molar region bilaterally. In the same session, the third and fourth premolars were extracted bilaterally and one implant of each type was immediately placed into the extraction socket. The dogs were euthanized at 14 and 28 days following surgery, and the peri-implant bone reaction was assessed histologically using Stevenel's blue and alizarin red in nondecalcified sections. RESULTS: The postoperative healing was uneventful. The 14-day histologic analysis reported nonsignificant results in terms of difference between the groups, while significant results were found 28 days after surgery. In fact, a significantly higher rate of new bone around the implant was reported in the Nano-Active compared to the Nano groups (51.0% ± 10.2% vs 36.0% ± 10.2%) and Hydro compared to the Nano groups (47.3% ± 10.7% vs 36.0% ± 10.2%). CONCLUSION: The results obtained indicate that new bone formed after 4 weeks demonstrated a tendency for dry salt-treated bioactivated surfaces to improve bone deposition in the interface in the early stages of healing; however, due to the limited number of dogs, the results failed to show a statistical significance. A study with a significantly larger group of animals should be performed in order to challenge the assumption that ultra-hydrophilic-surface implants might show higher bone-implant contact in immediate postextraction replacement.

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.

Maxillary Sinus Augmentation Using Ceramic Alloplastic Granules or Paste: An Experimental Study in Rabbits.

BACKGROUND: Due to the lack of data comparing the biological behavior of two formulations, granules and paste, of alloplastic graft from microtomographic and histomorphometric points of view, the aim of the present experiment was to compare the histomorphometric and microtomographic healing of two formulations, i.e., granules (MR sites) or paste (MR-inject sites) of an alloplastic graft composed of a combination of beta-tricalcium phosphate and hydroxyapatite used for maxillary sinus lifting. METHODS: A sinus lifting procedure was carried out bilaterally in 20 rabbits, and the elevated space was filled with either paste or granules of an alloplastic material. A collagen membrane was placed on the antrostomy and the animals were euthanized after 2 or 10 weeks, 10 animals each group. Microtomographic and histological analyses were performed. RESULTS: Higher proportions of new bone formation were found at the MR, compared to the MR-inject sites both after 2 weeks (2.65 ± 2.89% vs. 0.08 ± 0.12%; p < 0.01) and 10 weeks of healing (34.20 ± 13.86 vs. 23.28 ± 10.35%; p = 0.022). CONCLUSIONS: It was concluded that new bone formation was faster in the MR sites, compared to the MR-inject. However, a longer time of healing should be allowed to make final conclusions about the efficiency in bone formation of the paste formulation of the biomaterial used in the present study.

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 Effect of Coronal Implant Design and Drilling Protocol on Bone-to-Implant Contact: A 3-Month Study in the Minipig Calvarium.

Background: Stress concentrated at an implant's neck may affect bone-to-implant contact (BIC). The objective of this study was to evaluate four different implant neck designs using two different drilling protocols on the BIC. Methods: Ninety-six implants were inserted in 12 minipigs calvarium. Implants neck designs evaluated were: type 1-6 coronal flutes (CFs), 8 shallow microthreads (SMs); type 2-6 CFs,4 deep microthreads (DMs); type 3-4 DMs; type 4-2 CFs, 8 SMs. Two groups of forty-eight implants were inserted with a final drill diameter of 2.8 mm (DP1) or 3.2 mm (DP2). Animals were sacrificed after 1 and 3 months, total-BIC (t-BIC) and coronal-BIC (c-BIC) were evaluated by nondecalcified histomorphometry analysis. Results: At 1 month, t-BIC ranged from 85-91% without significant differences between implant types or drilling protocol. Flutes on the coronal aspect impaired the BIC at 3 m. c-BIC of implant types with 6 CFs was similar and significantly lower than that of implant types 3 and 4. c-BIC of implant type 4 with SMs was highest of all implant types after both healing periods. Conclusions: BIC was not affected by the drilling protocol. CFs significantly impaired the -BIC. Multiple SMs were associated with greater c-BIC.

Ridge Augmentation Using Customized Allogeneic Bone Block: A 3-Year Follow-up of Two Case Reports.

A variety of surgical techniques and grafting materials for the purpose of ridge augmentation have been developed during the last three decades. Recently, the use of customized allogeneic bone blocks, prepared by CAD/CAM techniques, has been introduced. This new augmentation technology may significantly reduce surgical time and improve donor-recipient fit and adaptation. However, promising clinical and histologic results have been published in only a few short-term case reports. The 3-year follow-ups of these two case reports may provide more clinical data on the use of the customized bone blocks for horizontal and vertical ridge augmentation in the posterior mandible.

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.

Clinical and radiological outcomes of implants with two different connection configurations: A randomised controlled trial.

Background: Peri-implant marginal bone loss is influenced by the interaction between tissues and the implant­abutment complex. The implant­abutment connection geometry is considered to be one of the factors that most affects peri-implant bone remodelling. Purpose: The primary purpose was to compare the clinical and radiographical differences between implants sharing the same macrogeometry but with two different connections. The secondary aims were to measure implant success and survival rate, primary and secondary stability, and the correlation between changes in marginal bone level and clinical variables. Additionally, a neural network was developed and tested to anticipate the impact of the insertion torque curve on marginal bone loss. Materials and methods: Patients requiring at least two implants in the posterior region were randomly divided into two groups. The implants presented the same micro- and macrotopography with different internal connections, conical standard (CS) and internal hex (IH). Upon implant surgery (T0), insertion torque, implant stability (implant stability quotient values were recorded by resonance frequency analysis), soft tissue height and the amount of keratinised gingiva were assessed. Stability was remeasured at the time of prosthetic connection (stage-two surgery) using a one-abutment one-time protocol and a fully digital workflow. At 6 months and 1 year after implant loading, periodontal parameters were assessed and periapical radiographs were taken. To study the differences between the two groups and the different variables, paired t test and generalised estimating equations models were adopted. Cluster analysis was used to assess the correlation between torque insertion/clinical profiles and changes in marginal bone level. Results: A total of 33 patients (17 men, 16 women, mean age 67.4 ± 14.5 years) were included in the study. No dropouts were reported. Fifty-three implants (26 CS and 27 IH) were inserted in the maxilla, and 15 (8 CS and 7 IH) in the mandible. No implants failed. Marginal bone loss at 6 months after prosthetic loading was 0.33 ± 0.34 mm for CS and 0.43 ± 0.37 mm for IH (P = 0.125), and after 1 year was 0.48 ± 0.18 mm for CS and 0.57 ± 0.24 mm for IH. A statistically significant difference between the implant stabilty quotient values for the test and control groups was demonstrated at T0 (P = 0.03) and at stage-two surgery (P = 0.000122). The generalised estimating equations model showed that soft tissue height (P = 0.012), keratinised gingiva (P = 0.05) and insertion torque (P = 0.042) had a significant effect on marginal bone loss, while the other variables did not play a statistically significant role. The neural network showed good sensitivity, accuracy, precision and specificity. Conclusions: The present research showed that different implant­abutment connections with the same implant macrogeometry have a significant effect on marginal bone loss. Better outcomes were observed in the CS group compared to the IH group. Marginal bone loss was found to be influenced by different individual and clinical factors.

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.

Socket-shield technique: the influence of the length of the remaining buccal segment of healthy tooth structure on peri-implant bone and socket preservation. A study in dogs.

OBJECTIVE: The aim of this study was to evaluate the influence of the location and length of root pieces on buccal peri-implant bone width and socket preservation in socket shield technique. MATERIAL AND METHODS: Forty-eight dental implants (24 narrow and 24 regular platform internal hex implants) were placed in six dogs. The clinical crowns of teeth P2, P3, P4 and M1 were detached horizontally and removed from the underlying roots. Then the mesial root of each tooth was extracted and the distal root was degraded using a high-speed hand-piece with round bur, creating a concave shell of dentin cementum and periodontal ligament (PDL) connected to the buccal aspect of the socket. Remaining root fragments of different lengths were created: coronal (1/3); middle and coronal (2/3); full length (3/3). These were positioned all around the bone crest. Implants were placed at the center of the root sockets, 1-3mm deeper than the original root apex. RFA and histological evaluations were made at 4 and 12 weeks. Data underwent statistical analysis (p<0.05). RESULTS: All 48 implants osseointegrated satisfactorily. On both buccal and lingual sides, the coronal (1/3) radicular fragment was attached to the buccal bone plate by physiologic periodontal ligament with less crestal bone resorption compared with middle (2/3) and whole root (3/3) groups for narrow and standard implants. CONCLUSIONS: Within the limitations of this study, the results demonstrate that a small piece of root in the coronal part of the alveolus can protect the buccal, mesial and distal bone crest following the immediate placement of NeO narrow or NeO Standard Internal Hex implants. The thickness of peri-implant bone and the remaining root fragment together will provide a total thickness of >2mm. The technique would appear to be highly predictable, maintaining bone volume and reducing the risk of crestal bone resorption.

Direct Contact Test for Evaluating Bacterial Growth on Machined and Rough Surface Implants: An In Vitro Study.

OBJECTIVE: To use a modified direct contact test (DCT) to evaluate the bacterial growth on 3 commercially available implants. MATERIALS AND METHODS: Streptococcus salivarius growth was tested on 1 machined surface and 2 commercial rough surface implants. Seven implants from each group were fixed to the cover of a 96-well microtiter plate. Bacterial suspension was placed on each implant, and the plate was incubated at 37°C for 1 hour to allow the suspension fluid to evaporate. Fresh medium was added to 7 corresponding wells in the microtiter plate, and the cover holding the implants was placed on the plate to enable immersion of the implant. Noncontaminated implant samples served as control. Bacterial growth was monitored spectrophotometrically at 650 nm for 24 hours. RESULTS: There was a significant S. salivarius growth in all groups of test implants compared with the control. There was no significant difference between bacterial growth kinetics on treated and nontreated implant surfaces (P = 0.241). CONCLUSION: Using the DCT, we found no difference in bacterial growth between machined and rough surface implants.

Histological and radiological evaluation of sintered and non-sintered deproteinized bovine bone substitute materials in sinus augmentation procedures. A prospective, randomized-controlled, clinical multicenter study.

OBJECTIVES: The objective of this study is to histologically and radiologically compare a sintered and a non-sintered bovine bone substitute material in sinus augmentation procedures. MATERIALS AND METHODS: Thirty-three patients were included in the clinically controlled randomized multicentre study resulting in a total of 44 treated sinuses. After lateral approach, sinuses were filled with either a sintered (SBM, Alpha Bio's Graft®) or a non-sintered (NSBM, Bio Oss®) deproteinized bovine bone substitute material. The augmentation sites were radiologically assessed before and immediately after the augmentation procedure as well as prior to implant placement. Bone trephine biopsies for histological analysis were harvested 6 months after augmentation whilst preparing the osteotomies for implant placement. RESULTS: Healing was uneventful in all patients. After 6 months, radiological evaluation of 43 sinuses revealed a residual augmentation height of 94.65 % (±2.74) for SBM and 95.76 % (±2.15) for NSBM. One patient left the study for personal reasons. Histological analysis revealed a percentage of new bone of 29.71 % (±13.67) for SBM and 30.57 % (±16.07) for NSBM. Residual bone substitute material averaged at 40.68 % (±16.32) for SBM compared to 43.43 % (±19.07) for NSBM. All differences between the groups were not statistically significant (p > 0.05, Student's t test). CONCLUSION: Both xenogeneic bone substitute materials showed comparable results regarding new bone formation and radiological height changes in external sinus grafting procedures. CLINICAL RELEVANCE: Both bone substitute materials allow for a predictable new bone formation following sinus augmentation procedures.

Dental implants in medically complex patients-a retrospective study.

INTRODUCTION: Dental implant insertion for oral rehabilitation is a worldwide procedure for healthy and medically compromised patients. The impact of systemic disease risks on the outcome of implant therapy is unclear, since there are few if any published randomized controlled trials (RCTs). OBJECTIVE: The objective of this study is to investigate the rate of complications and failures following dental implantation in medically compromised patients in order to elucidate risk factors and prevent them. MATERIAL AND METHODS: A retrospective cohort study was conducted from patient files treated with dental implantation between the years 2008-2014. The study group consisted of medically complex patients while the control group consisted of healthy patients. Preoperative, intraoperative, and post operative clinical details were retrieved from patients' files. The survival rate and the success rate of the dental implants were evaluated clinically and radiographically. RESULTS: A total of 204 patients (1003 dental implants) were included in the research, in the study group, 93 patients with 528 dental implants and in the control group, 111 patients with 475 dental implants. No significant differences were found between the groups regarding implant failures or complications. The failure rate of dental implants among the patients was 11.8 % in the study group and 16.2 % in the control group (P = 0.04). It was found that patients with a higher number of implants (mean 6.8) had failures compared with patients with a lower number of implants (mean 4.2) regardless of their health status (P < 0.01). CONCLUSIONS: We found a similar rate of failure and complications of dental implantation in medically complex patients and in healthy patients. CLINICAL RELEVANCE: Medically complex patients can undergo dental implantation. There are similar rates of complications and failures of dental implants in medically complex patients and in healthy patients.

Differences in crestal bone-to-implant contact following an under-drilling compared to an over-drilling protocol. A study in the rabbit tibia.

OBJECTIVES: The objective of this study is to compare bone-to-implant contact (BIC) between implants inserted at high torque due to under-drilling of the crestal bone to those inserted at low torque due to over-drilling of the crestal bone. MATERIALS AND METHODS: Forty implants with diameters of 3.75 mm (group A) or 3.55 mm (group B) were inserted in the proximal tibiae of NZW rabbits in two separate surgeries on day 0 or 21. Osteotomy of the crestal bone was finalized with a 3.65-mm drill. In group A, implants were inserted at torque ≥35 Ncm (under-drilling) and in group B with torque <10 Ncm (over-drilling). Implants and their surrounding bone were retrieved on day 42, thus creating 3- and 6-week observation periods, processed for non-decalcified histology and stained with toluidine blue. Crestal BIC (c-BIC) and total BIC (t-BIC) were measured. Wilcoxon test was used to evaluate differences between groups. RESULTS: Three weeks post-surgery, the mean c-BIC in group A was 16.3 ± 3.3 vs 31.5 ± 3.4 % in group B (P < 0.05). At 6 weeks, a similar trend was observed (group A: 28.7 ± 3.6 %; group B: 38.4 ± 4.9 %) (P > 0.05). No differences in t-BIC were noted at 3 weeks and at 6 weeks between the groups. CONCLUSIONS: Insertion of implants with an over-drilling protocol of the crestal aspect of the osteotomy resulted in increased short-term crestal bone-to-implant contact. CLINICAL RELEVANCE: Insertion of implants with a high torque following an under-drilling protocol, commonly used for immediate loading, may reduce crestal bone-to-implant contact at early healing stages.

Accelerated degradation of collagen membranes in diabetic rats is associated with increased infiltration of macrophages and blood vessels.

OBJECTIVES: Increased collagenolytic activity in diabetes may compromise collagen membrane (CM) survival. Tetracycline (TTC) possesses anti-collagenolytic properties and delays CM degradation. This study evaluated macrophage and capillary infiltration within CMs in diabetic rats. MATERIALS AND METHODS: Diabetes was induced in 20 Wistar rats by streptozotocin and 20 served as controls. Biotin-labeled CM discs were immersed in either TTC (50 mg/ml) or PBS. In each animal, 2 discs (TTC and control) were implanted under the parietal periosteum and rats were sacrificed at 2 or 4 weeks post-implantation. The area and thickness of the residual disc collagen were measured following staining with streptavidin, and the number of macrophages and blood vessels within the membranes was determined using specific antibodies (to CD68 and transglutaminase II, respectively). RESULTS: Diabetes significantly reduced the area and thickness of the CMs, while TTC increased CM thickness significantly in both groups of rats at 2 and 4 weeks. Diabetes increased the number of macrophages (∼eightfold at 2 weeks and ∼fourfold at 4 weeks), but TTC had no significant effect. Finally, diabetes increased the number of blood vessels within the discs (∼threefold at 2 weeks and ∼twofold at 4 weeks), while TTC had no effect. CONCLUSIONS: Diabetes increases degradation of native CMs and the number of blood vessels and macrophages within them. TTC immersion delays CM degradation without an apparent effect on macrophage and blood vessel penetration. CLINICAL RELEVANCE: Enhanced CM degradation in diabetic conditions which impair guided regenerative procedure outcome is apparently related to increased blood vessel formation and macrophage infiltration.

Tetracycline impregnation affects degradation of porcine collagen matrix in healthy and diabetic rats.

OBJECTIVES: The present study evaluated the degradation of collagen matrix (CM) immersed in tetracycline (TTC) or phosphate-buffered saline (PBS) in diabetic and normoglycemic rats. MATERIALS AND METHODS: Diabetes was induced in 15 rats by systemic streptozotocin (STZ) (experimental); 15 healthy rats served as controls. One day before implantation 60 CM disks, 5 mm in diameter, were labeled with biotin: 30 were immersed in tetracycline (TTC) and 30 in PBS. One disk of each type was implanted subdermally in each rat. Animals were euthanized after 3 weeks, and tissue specimens containing the disks were prepared for histologic analysis. Horseradish peroxidase (HRP)-conjugated streptavidin was used to detect the remaining biotinylated collagen. Residual collagen area within the CM disks was analyzed and compared to baseline. RESULTS: Diabetes significantly increased the CM degradation. Immersion of the CM disks in a 50-mg/mL TTC solution before implantation decreased its degradation both in diabetic and normoglycemic rats. CONCLUSIONS: Diabetes significantly increases collagen matrix degradation; immersion of collagen matrix in TTC before implantation decreases its degradation in both diabetic and normoglycemic conditions. CLINICAL RELEVANCE: Immersion of medical collagen devices in TTC may be an effective means to decrease their resorption rate and increase their effectiveness, especially in situations with increased degradation such as diabetes.

Evaluation of a topical herbal patch for soft tissue wound healing: an animal study.

AIM: This study evaluated the effects of a topical herbal patch (PerioPatch®) for gingival wound healing in a rat model. MATERIALS AND METHODS: A mid-crestal incision was performed on each side of the edentulous anterior maxilla in 48, 6-month-old, Wistar rats. Full-thickness flaps were raised, repositioned and sutured. Four experimental groups were established: herbal patch, placebo patch, no patch and no patch and no surgery. Patches were placed immediately after surgery and replaced every 12 h for the following 3 days. Half of the animals were killed after 5 and the remaining ones after 12 days. Tissue blocks were retrieved and processed for histological and immunohistochemical evaluation. Epithelial gap, collagen contents, amount of macrophages, cellular proliferation and vascular contents were evaluated in the central incision area. Statistical analysis consisted of two-way anova. RESULTS: The herbal patch group presented the smallest epithelial gap at 12 days, the highest collagen content both at 5 and 12 days, a larger number of proliferating cells at day 5 and more numerous blood vessels at day 12. Macrophage number was similar in all groups. CONCLUSION: Herbal patch improved wound healing in this animal model.