Assessment of dentin mineral density of human teeth using micro-computed tomography in two kilovoltage levels.

A significant advancement in micro-computed tomography (µCT) translational application in endodontics has occurred. The purpose of the study was to assess the applications of a new method to measure dentin mineral density (DMD) and to compare between 2 levels of energy sources. Two sets of standardized porous solid hydroxyapatite (HA) phantoms, with mineral densities of 0.25 g/cm3 and 0.75 g/cm3, respectively were embedded in aluminum foil. The µCT homogeneity and noise in the HA phantoms were analyzed using 50 kV and 100 kV energy sources. DMD of 66 extracted human teeth was measured at the cemento-enamel junction (CEJ), mid-root, and apical levels. Assessment included linearity between the energy source and the DMD measurement. The quality of the images obtained from the 2 energy sources was compared and analyzed statistically. HA phantom rods and validation methods showed that 100 kV provided a more accurate measurement of the DMD in all groups tested. The 100 kV 3D reconstructed µCT images displayed a more defined details of the dentin structure. A statistically significant difference was found between 100 and 50 kV (p < 0.05) in all measured areas except for the mid-root. Using micro-computed tomography is a practical and non-destructive method to measure dentin density. 100 kV energy source provides clearer and more consistent images.

NF-κB inhibits osteogenic differentiation of mesenchymal stem cells by promoting ß-catenin degradation.

Mesenchymal stem cell (MSC)-based transplantation is a promising therapeutic approach for bone regeneration and repair. In the realm of therapeutic bone regeneration, the defect or injured tissues are frequently inflamed with an abnormal expression of inflammatory mediators. Growing evidence suggests that proinflammatory cytokines inhibit osteogenic differentiation and bone formation. Thus, for successful MSC-mediated repair, it is important to overcome the inflammation-mediated inhibition of tissue regeneration. In this study, using genetic and chemical approaches, we found that proinflammatory cytokines TNF and IL-17 stimulated IκB kinase (IKK)-NF-κB and impaired osteogenic differentiation of MSCs. In contrast, the inhibition of IKK-NF-κB significantly enhanced MSC-mediated bone formation. Mechanistically, we found that IKK-NF-κB activation promoted ß-catenin ubiquitination and degradation through induction of Smurf1 and Smurf2. To translate our basic findings to potential clinic applications, we showed that the IKK small molecule inhibitor, IKKVI, enhanced osteogenic differentiation of MSCs. More importantly, the delivery of IKKVI promoted MSC-mediated craniofacial bone regeneration and repair in vivo. Considering the well established role of NF-κB in inflammation and infection, our results suggest that targeting IKK-NF-κB may have dual benefits in enhancing bone regeneration and repair and inhibiting inflammation, and this concept may also have applicability in many other tissue regeneration situations.

Guided bone regeneration in standardized calvarial defects using beta-tricalcium phosphate and collagen membrane: a real-time in vivo micro-computed tomographic experiment in rats.

Guided bone regeneration (GBR) procedures using graft materials have been used for reconstruction of osseous defects. The aim of the present in vivo micro-computed tomographic (µCT) and histologic study was to assess in real time the bone regeneration at GBR sites in standardized experimental calvarial defects (diameter 3.3 mm) using ß-tricalcium phosphate (ß-TCP) with and without collagen membrane (CM). A single full-thickness calvarial defect was created on the left parietal bone in young female Wistar albino rats (n = 30) weighing approximately 300 g and aged about 6 weeks. The animals were randomly divided into three groups for treatment, based on calvarial defect filling material: (1) control group (n = 10); (2) ß-TCP + CM group (n = 10); (3) ß-TCP group (n = 10). Real-time in vivo µCT analyses were performed immediately after surgery and at 2, 4, 6 and 10 weeks to determine the volume and mineral density of the newly formed bone (BVNFB, MDNFB) and remaining ß-TCP particles (VRBP, MDRBP). The animals were killed at 10 weeks and calvarial specimens were evaluated histologically. In the control group, MDNFB increased significantly at 6 weeks (0.32 ± 0.002 g/mm(3), P < 0.01) compared to that at baseline. In ß-TCP + CM group, BVNFB (1.10 ± 0.12 mm(3), P < 0.01) and MDNFB (0.13 ± 0.02 g/mm(3), P < 0.01) significantly increased at the 4th week than baseline. In the ß-TCP group, BVNFB (1.13 ± 0.12 mm(3), P < 0.01) and MDNFB (0.14 ± 0.01 g/mm(3), P < 0.01) significantly increased at 6 weeks compared to that at baseline. Significant reduction in VRBP was neither seen in the ß-TCP + CM group nor in the ß-TCP group. While in the ß-TCP + CM group MDRBP was reduced significantly at 6 weeks (0.44 ± 0.9 g/mm(3), P < 0.01) from baseline (0.98 ± 0.03 g/mm(3)), similar significant reduction in MDRBP from baseline (0.92 ± 0.07 g/mm(3)) was seen only at 10 weeks (0.45 ± 0.06 g/mm(3), P < 0.05) in the ß-TCP group. Histologic findings at 10 weeks revealed greater amount of NFB with osteocytes in the matrix, in the ß-TCP + CM group than in the ß-TCP group. Biomechanical assessment of NFB for hardness (H) and elastic modulus (E) revealed significantly higher values for the ß-TCP + CM group (H = 612.6 ± 4.28 Mpa; E = 13.57 ± 0.07 Gpa) when compared to those of the control (H = 192.1 ± 4.93 Mpa; E = 6.76 ± 0.04 Gpa) and the ß-TCP groups (H = 241.9 ± 6.29 Mpa; E = 4.34 ± 0.06 Gpa). In conclusion, based on real-time assessment, NFB is formed in calvarial defects as early as 4 weeks following GBR with ß-TCP + CM as compared to 6 weeks when ß-TCP alone was used.

A randomized clinical trial evaluating the efficacy of the sandwich bone augmentation technique in increasing buccal bone thickness during implant placement. II. Tomographic, histologic, immunohistochemical, and RNA analyses.

OBJECTIVES: This study aimed to evaluate the biologic and structural phenotypes of the bone regenerated via the sandwich bone augmentation (SBA) technique, on buccal implant dehiscence defects. MATERIAL AND METHODS: Twenty-six patients with one buccal implant dehiscence defect each were randomly assigned to two groups. Both groups received a standardized amount of mineralized cancellous and cortical allogenic bone graft. In the test group, a bovine pericardium membrane was placed over the graft, while no membrane was placed in the control group. After 6 months of healing, a bone core biopsy of the regenerated bone was harvested and processed for histologic, immunohistochemical, mRNA, and micro-computed tomography (µCT) analyses. Of the 26 bone core biopsies, only six cores from the test group and six cores from the control group were suitable for the analysis. RESULTS: Bone volume (BV) in the test group was maintained, but tissue maturation appeared to be delayed. In contrast, tissue maturation appeared to be completed in the control group, but BV was compromised. Micro-CT analysis showed that specimens from the control group were more structured and mineralized compared with those from the test group. Histologic analysis showed more residual graft particles scattered in a loose fibrous connective tissue matrix with sparse bone formation in the test group, while the control group showed obvious vital bone formation surrounding the residual graft particles. Positive periostin (POSTN), sclerostin, and runt-related transcription factor-2 (RUNX2) immunoreactivities were detected in both the control and test groups. However, tartrate-resistant acid phosphatase (TRAP) positive was mostly noted in the control group. There were significant differences in POSTN, RUNX2 and VEGF expressions between the test and control groups. CONCLUSION: These findings indicated that the SBA technique was an effective method in preserving adequate structural volume while promoting new vital bone formation. Use of the collagen barrier membrane has successfully maintained the volumetric dimensions of the ridge but might have slowed down the complete maturation of the outermost layer of the grafted site.

Comparison between sandwich bone augmentation and allogenic block graft for vertical ridge augmentation in the posterior mandible.

INTRODUCTION: The purpose of this randomized controlled clinical trial was to evaluate 2 different techniques for vertical ridge augmentation (VRA) of the posterior mandible. MATERIALS AND METHODS: Sixteen subjects with 19 posterior mandibular edentulous sites requiring VRA were recruited for the study. Sites were randomly treated with either block allograft (BA; N = 9) or sandwich bone augmentation (SBA; N = 10). Clinical measurements were recorded at the time of surgery (baseline) and 6-month reentry with a custom-made acrylic surgical template. RESULTS: The mean vertical bone gain (VBG) after mean 6.8 months was 44.5% (mean = 1.78 mm [0-5 mm]) in the BA group and 33.3% (mean = 1.0 mm [-1 to 3 mm]) in the SBA group. Significantly higher rates of incision line openings and wound dehiscences were found in the BA group (n = 7/9, 77.8%) as compared with the SBA group (n = 3/10, 30%) (P = 0.037). After adjusting for graft exposure, BA group demonstrated significantly higher VBG than SBA (difference = 2.26 mm, P < 0.001). In addition, graft exposure resulted in significantly less VBG in both groups (P < 0.001). CONCLUSIONS: A higher tendency of wound exposure during VRA was demonstrated when a BA was used compared with the SBA technique. However, if wound exposure could be prevented, higher vertical ridge gain could be achieved with a BA. SUMMARY: The use of a BA in VRA resulted in a maximum of 2 mm more bone height gain compared with the SBA technique if the primary coverage can be achieved during the healing.

Bond strength and micro-computed tomographic evaluation of pre-coated brackets.

OBJECTIVES: The aim of the present study was to assess and compare the shear bond strength (SBS) of metal pre-coated orthodontic brackets bonded to fluorotic and non-fluorotic teeth treated with three different etching techniques. A second aim was to determine the volume of adhesive remaining on the tooth at debond using micro-computed tomography (µCT). METHODS: Ninety extracted premolars were selected to include 45 fluorotic (test group) and 45 non-fluorotic (control group) teeth. Each group was divided into three subgroups of 15 each, which were treated as follows: 1) micro-etched; 2) acid-etched; and 3) both micro-etched and acid-etched. A bonding agent was applied to the prepared surfaces; pre-coated and light-cured brackets were attached to all teeth. An Instron universal testing machine was used to record the debonding force. Specimens were then scanned using a microCT to evaluate the amount of adhesive remaining on the teeth. The significance of the statistical tests was pre-determined at p < 0.05. RESULTS: Two-way ANOVA showed that fluorosis of teeth had no influence on the SBS (p = 0.165) whereas the volume of adhesive remnants was significantly higher in the control group compared with the test group (p < 0.001). CONCLUSIONS: Fluorosis had no influence on the SBS of brackets, whereas it had a negative influence on retaining adhesives onto the tooth surfaces.

Evaluation of mandibular lingual foramina related to dental implant treatment with computerized tomography: a multicenter clinical study.

BACKGROUND: Bleeding can be one of the severe complications during implant placement or other surgeries. Presurgical assessment of the area should be performed precisely. Thus, we examined lingual vascular canals of the mandible using dental computerized tomography (CT); define the anatomical characteristics of canals and the relationship with mandibular bone. METHODS: One thousand sixty-one foramina in 639 patients, in 5 dental clinics, were included in this multicenter study. Distance between crest and lingual foramen, tooth apex and lingual foramen, distance from mandibular border, diameter of lingual foramen, canal type, anastomosis, and location of foramen were examined. RESULTS: Foramen was 18.33 ± 5.45 mm below the bony crest and 17.40 ± 7.52 mm from the mandibular border, with men showing larger measurements. The mean diameter of lingual foramina was 0.89 ± 0.40 mm; 76.8% canal type was mono; 51.8% patients presented with median lingual canal-foramen (MLC) and 21.1% with lateral lingual foramen. Diameter of MLC was statistically larger. CONCLUSIONS: With a large sample group, results represented that lingual foramina could be visualized with dental CT, providing useful data for mandibular implant surgeries. Findings suggest that vascular canals and several anastomoses exist in the anterior mandible extending through premolar and molar regions as well. It is imperative to consider these vessels with the dental CT before and during the mandibular surgery to prevent threatening hemorrhage.

Efficacy of growth factor in promoting early osseointegration.

A preclinical study was conducted to evaluate the feasibility of 2 different topical formulations of recombinant human platelet-derived growth factor-BB (rhPDGF-BB) to promote early osseointegration and enhanced bone-to-implant contact (BIC) for dental implants placed in an edentulous ridge. Six female beagle dogs were divided into 3 groups. The control group included 4 implants with no coating; test group A included 10 implants with commercially available rhPDGF-BB formulation coating; and second test group B included 10 implants with prototype viscous rhPDGF-BB coating. Three dogs were sacrificed at 3 weeks (12 implants) and the remaining 3 dogs at 6 weeks after implant placement (12 implants). The specimens were retrieved for histological evaluation, and revealed an uneventful healing of all implants without any sign of an inflammatory response at the different time intervals. Furthermore, the bone was in very close contact with the implants' surfaces with no evidence of intervening fibrous tissue layers. At 3 weeks, new bone formation between most implant threads on rhPDGF-BB coated implants was evident, whereas in the control group only a thin and sparse amount of new bone was noted. At 6 weeks, the commercially available rhPDGF-BB formulation coated implant group (Group A) showed more trabecular bone and higher BIC compared to the other 2 groups. Histologically, the results in this study showed that use of conventionally available rhPDGF-BB formulation as the implant surface treatment may accelerate the process of osseointegration and enhance BIC.

Oral Candida carriage and species prevalence amongst habitual gutka-chewers and non-chewers.

Oral Candida colonisation is higher in tobacco smokers as compared to non-smokers; however, it remains unknown whether smokeless tobacco chewers are susceptible to increased oral Candida colonisation. The aim was to determine the oral Candida carriage and species prevalence amongst habitual gutka-chewers and non-chewers in a cohort from Karachi, Pakistan. Forty-five gutka-chewers and 45 non-chewers were included. Information regarding age, sex, duration of gutka-chewing habit, daily frequency of gutka consumption, duration of holding gutka in the mouth, daily frequency of tooth-brushing and tongue brushing was collected using a questionnaire. Oral yeast samples were collected by scraping the dorsum of the tongue and bilateral buccal mucosa with a sterile cotton swab. Identification of yeast species was performed using standard techniques. Tongue lesions were identified and recorded. Unstimulated whole salivary flow rate (UWSFR) was also measured. There was no significant difference in the mean age, UWSFR and oral Candida carriage among gutka-chewers and non-chewers. Individuals were chewing gutka since 4·4 years and were consuming five gutka sachets daily. Candida albicans (C. albicans) was the most common yeast species isolated from 57·8% gutka-chewers and 64.4% non-chewers. In 24.4% gutka-chewers and 22·2% non-chewers, two candidal strains (C. albicans and Candida tropicalis) were isolated. In conclusion, the present results indicated no significant difference in oral Candida carriage in habitual gutka-chewers and non-chewers.

Effect of Recombinant Human Platelet-Derived Growth Factor on Healing of Chronic Periapical Tissue Pathosis Following Apical Surgery in a Canine Model: A Histomorphometric and Microcomputed Tomography Analysis.

This canine in vivo study assessed the effect of recombinant human platelet-derived growth factor (rhPDGF) on the healing of periapical tissues following apical surgery. From a total of 96 premolar teeth, 64 teeth from six beagle dogs (2 years old) were classified as experimental and were randomly assigned to four experimental groups (16 teeth per group). After having the pulp extirpated, leaving teeth open to the oral cavity for 1 week, and sealing with an immediate restorative material for 8 weeks, nonsurgical endodontic treatment was performed. A split-mouth design was used, and intra-animal randomization of treatment sides was applied to the groups as follows: apical curettage + 1.5-mm root-end resection (Group 1); apicoectomy + mineral trioxide aggregate (MTA) root-end filling (Group 2); apicoectomy + MTA root-end filling + rhPDGF (Group 3); and apical curettage + rhPDGF (Group 4). The animals were sacrificed 24 months after apical surgery, and histologic and µCT analyses were performed for bone volume loss (BVL). Group 1 showed partial resolution of the periapical lesions without signs of tissue regeneration (BVL: 49.09 ± 10.97 mm3). Group 2 had minimal bone regeneration and showed cementum reformation in 9 teeth, with no direct attachment to the MTA (BVL: 35.34 ± 10.97 mm3). Group 3 showed regeneration of all damaged apical tissues without direct contact between the cementum and MTA (BLV: 4.51 ± 1.55 mm3). Group 4 showed regeneration of PDL, bone, and cementum and attachment of functional cementum fibers (BVL: 2.82 ± 2.3 mm3). The difference in BVL was statistically significant only for Groups 1 and 2 (P < .05). rhPDGF may help regenerate apical tissue structures following apical surgery.

Efficacy of using a dual layer of membrane (dPTFE placed over collagen) for ridge preservation in fresh extraction sites: a micro-computed tomographic study in dogs.

OBJECTIVE: To assess if overbuilding the buccal plate or using a dual-layer socket grafting technique prevents alveolar bone resorption and enhances final ridge width, height, and volume after tooth loss in an animal model. MATERIAL AND METHODS: In eight beagle dogs bilateral second (P2)-, third (P3)-, and fourth (P4) premolars were endodontically treated. All bilateral mandibular first premolars and distal roots of P2, P3, and P4 were hemisectioned and atraumatically extracted. Animals were randomly divided into four groups: (i) Control-Socket alone, (ii) Particulate allograft in the alveolum, socket covered with high-density polytetrafluoroethylene (dPTFE) membrane and sutured over the alveolum, (iii) Particulate allograft in the alveolum and overbuilding the buccal plate, socket covered with dPTFE membrane and sutured over the alveolum, (iv) Particulate allograft in the alveolum and covered with dual layer (dPTFE placed over collagen membrane), and sutured over the alveolum. After 16 weeks, the animals were sacrificed. Mandibular blocks of the jaws were assessed for bone volume (BV), vertical bone height (VBH), alveolar ridge thickness, and bone mineral density (BMD) using micro-computed tomography. RESULTS: The BV in groups 1, 2, 3, and 4 was 169.5, 207.57, 242.4, and 306.1 mm(3) , respectively. The VBH in groups 1, 2, 3, and 4 was 4.2, 6.4, 6.2, and 7.3 mm, respectively. Ridge widths in groups 1, 2, 3, and 4 were 5.45 ± 0.75, 5.91 ± 0.86, 6.05 ± 0.63, and 6.28 ± 1.01 mm, respectively. There was no significant difference in BMD between the groups. CONCLUSIONS: The RP using a dual layer of membrane following tooth extraction results in more BV, VBH, and alveolar ridge width as compared to when a single layer of membrane is used.

Is there a gender difference in anatomic features of incisive canal and maxillary environmental bone?

OBJECTIVES: The effect of gender on anatomic structures and various body systems were illustrated in the literature. The purpose of this study was to identify the influence of gender and tooth loss on incisive canal characteristics and buccal bone dimensions in the anterior maxilla. MATERIALS AND METHODS: Computed tomographies (CTs) of 417 male and 516 female patients in four dental clinics were included in this study. The diameter and the length of the incisive canal; width and the length of the bone anterior to the canal; palatal bone length, root length, and root width of the central incisor teeth were measured and recorded from CT sections. RESULTS: Mean incisive canal length was 11.96 ± 2.73 mm and 10.39 ± 2.47 mm in men and women, respectively, (P < 0.05). In men, mean canal diameter was 2.79 ± 0.94 mm whereas in women it was 2.43 ± 0.85 mm and this difference was statistically significant (P < 0.05). Men had significant higher buccal bone dimensions (length and width of the bone anterior to the canal) than women. Absence of teeth in the anterior maxilla decreased incisive canal length and buccal bone dimensions; however, canal diameter remain unchanged. CONCLUSIONS: Present results suggested a gender related differences in anatomic features of incisive canal and surrounding buccal bone. In addition, crestal canal diameter, buccal bone length, and thickness parameters might be different in distinct countries.

The influence of radiation therapy on dental implantology.

Patients with a history of head and neck cancer resection require extensive prosthodontic rehabilitation following cancer treatment. The oral anatomy drastically changes from ablative therapy, and the oral tissue response becomes altered as a consequence of radiation and chemotherapy. Successful restoration of oral function in this specific patient population was increasingly difficult before the widespread use of dental implants. Implant-borne prosthetics are now often used. However, surgical guidelines remain unclear with regard to oncology-related parameters. In this article, guidelines are introduced for implant therapy in the cancer patients according to radiation dosage and timing. Indications for hyperbaric oxygen treatment are highlighted along with risk assessment associated with implant placement. These guidelines are intended to augment knowledge obtained through oncology consultation; moreover, provide a rationale for implant therapy within the course of cancer treatment.

Effect of Selective Serotonin Reuptake Inhibitor (Paroxetine) on Newly Formed Bone Volume: Real-Time In Vivo Micro-computed Tomographic Analysis.

INTRODUCTION: Selective serotonin reuptake inhibitors (SSRIs) are commonly used to treat depression and anxiety. The purpose of this study was to assess in real time the effect of paroxetine, an SSRI, on newly formed bone volume (NFBV) in standardized calvarial defects (SCDs) in rats. METHODS: Fourteen Wistar albino female rats with a mean age of 7.5 months and a mean weight of 275 g were used. The animals were randomly divided into 2 groups. The experimental group was given paroxetine 8 weeks before the surgical procedure and throughout the experiment, and the control group was given a placebo 8 weeks before the surgical procedure and throughout the experiment. In each group, 14 SCDs measuring 4.6 mm in diameter were created on the parietal bone. In both groups, a Bio-Oss + collagen membrane was placed. All defects showed primary closure. The volume of the newly formed bone (NFBV) was measured using in vivo micro-computed tomographic imaging. Measurements were taken at days 0, 14, 28, 42, and 56 after surgery using real-time assessment with micro-computed tomographic imaging. RESULTS: The mean NFBV was 17.12 ± 4.52 mm3 and 12.52 ± 4.78 mm3 for the control and experimental groups, respectively, at day 56. The differences between the 2 groups were statistically significant (P < .05) at all time intervals. CONCLUSIONS: Paroxetine intake significantly reduced the amount of regenerated NFBV and the rate of new bone formation.

The effect of enamel matrix protein on gingival tissue thickness in vivo.

The enamel matrix derivative (EMD) has been used extensively as an adjunct to root coverage procedures to achieve periodontal regeneration. However, its effect on gingival tissues has not been elucidated. The aim of this investigation was to evaluate histometrically the change in gingival soft tissue thickness around dehiscence-type defects treated with EMD. Five adult female beagle dogs were used. Buccal osseous dehiscences were surgically created on the maxillary canines and the second and fourth premolars. Thirty defect sites were randomly assigned to test and control groups (15 defect sites for each group). The test group received EMD application, whereas the control group did not. After 4 months of healing, the dogs were killed and tissue blocks were prepared. Histometric analysis showed that the mean thickness of gingival tissue was 1.76 ± 0.23 mm in EMD-treated sites compared to 0.72 ± 0.11 mm for control sites. The difference between the test and control groups was statistically significant (P < 0.0001). It appears that EMD has a positive influence on the increase in gingival tissue thickness when used in dehiscence-type defects in the beagle dog.

Oral squamous cell carcinoma arising around osseointegrated dental implants.

PURPOSE: This literature review investigates the occurrence of oral squamous cell carcinoma (OSCC) around osseointegrated dental implants (DI). METHODS: Databases were searched from 1989 up to and including November 2011. The eligibility criteria were as follows: (1) original studies, (2) clinical studies and case reports, (3) reference lists of the relevant original and review articles, (4) intervention: occurrence of OSSC around osseointegrated DI, and (5) articles published only in English language. RESULTS: Fourteen studies were included. In nine studies, the dental implant patients with diagnosed OSCC had previously been exposed to cancer. In five studies, the patients presented with a history of habitual tobacco smoking and alcohol consumption. CONCLUSION: OSCC is more likely to arise around osseointegrated DI in patients with a previous history of cancer. However, the role of other factors including tobacco and alcohol usage cannot be disregarded.

Statins, glucocorticoids, and nonsteroidal anti-inflammatory drugs: their influence on implant healing.

This article aimed at exploring the effects of common systemic medications used in the United States and their effects on periimplant bone healing. An electronic search for articles evaluating the influence of systemic medications on periimplant bone healing was conducted using the PubMed (MEDLINE) database. Statins, when administered locally or systemically, were found to increase bone formation and density. A reduction in bone turnover and bone-to-implant contact was observed in animal models examining the effect of glucocorticoids on periimplant bone healing. Continued use of nonsteroidal anti-inflammatory drugs (NSAIDs) during or after implant placement was associated with reduced bone-to-implant contact, bone area, and bone density. Evidence seems to suggest that statins improve implant osseointegration. However, glucocorticoids and NSAIDs showed conflicting results. Therefore, more randomized clinical trials are needed to validate the effect of glucocorticoids and NSAIDs on periimplant bone healing.

Effect of enamel matrix derivative protein on the healing of standardized epithelial wounds: a histomorphometric analysis in vivo.

The enamel matrix derivative (EMD) is a preparation of the enamel matrix proteins secreted by the Hertwig's epithelial root sheath. It has been shown that EMD promotes periodontal wound healing; however, the significance of the protein in repairing skin wounds is insufficiently addressed. The aim of this in vivo histomorphometric investigation was to analyse the effect of EMD protein on the healing of standardised epithelial wounds. Dorsal skin of 22-week-old female guinea pigs (n = 33) was scarified and divided into test- (topical application of EMD) and control-sites (sutured and allowed to heal). Animals were euthanised at specific time intervals and the specimens were then evaluated histomorphometrically. The mean widths of the external wound gaps (WGs) in the test- and control-sites at the 5th, 20th and 35th day of healing were 5·89, 3·6 and 1·01 mm and 6·41, 5·02 and 3·43 mm, respectively. Histomorphometric analysis showed a statistically significant difference in the WGs between the test- and control-sites. A significant increase in the formation of organised connective tissue matrix, collagen fibres and early muscle formation was observed in the test-sites as compared with the control-sites. Within the limits of this study, it is concluded that topical application of the EMD on standardised epithelial allows early wound closure and promotes healing as compared to when the defects are merely sutured.

Proinflammatory cytokines in the crevicular fluid of patients with peri-implantitis.

The aim of this study was to review the proinflammatory cytokine profiles in the peri-implant crevicular fluid (PICF) of patients with peri-implantitis (PI). Databases were explored from 1994 up to and including July 2010 using various combinations of the following keywords: "cytokine", "crevicular fluid", "implant", "inflammation", "peri-implantitis" and "periodontitis". The eligibility criteria included: (1) original research articles; (2) clinical and experimental studies; (3) use of control group; (4) reference list of pertinent original and review studies; (5) use of statistical methods; (6) intervention: patients with and without PI; and (7) articles published only in English-language. Fifteen studies (14 case-controls and one case-report) were included. Four studies showed high levels of interleukin (IL)-1 beta (ß) in the PICF of implants affected by PI (test) compared to healthy (control) sites. Two studies showed an over-expression of IL-6 and IL-8 in the PICF of implants affected by PI compared to healthy implants. One study showed an increased secretion of IL-6, IL-8 and matrix metalloproteinase-1 by fibroblastic cells cultured from test- compared to control sites. Six studies reported high levels of tumor necrosis factor-alpha (TNF-α) levels in the PICF from test-sites (sites with PI) compared to the control sites. Two studies reported a positive association between polymorphism of IL-1 gene and PI. One study showed a negative association between polymorphism of TNF-α and an increased risk of PI. Raised levels of proinflammatory cytokines are exhibited in the PICF of patients with PI.

The feasibility of demineralized bone matrix and cancellous bone chips in conjunction with an extracellular matrix membrane for alveolar ridge preservation: a case series.

An investigation was conducted to test the feasibility of demineralized bone matrix and cancellous bone chips in a reverse-phase medium carrier (DynaBlast) in concert with an extracellular matrix membrane (DynaMatrix) to provide hard and soft tissue regeneration for the purpose of a ridge preservation procedure. Nine patients requiring extraction of 30 maxillary teeth were grafted with DynaBlast and DynaMatrix. Twenty sites attained primary flap closure over the grafted area (primary healing intention group), while 10 sites were assigned randomly to the secondary healing intention group, in which primary flap closure over the membrane was not achieved. Clinical and radiographic evaluations at 6 months revealed comparable bone formation for both groups. Histologic analyses of 21 harvested soft and hard tissue core biopsies revealed absence of the remnant membrane and consistent patterns of new bone formation. The efficacy and safety of DynaBlast and DynaMatrix have been validated clinically and histologically to preserve the dimensions of the alveolar process.