Unique inverse association between allergic rhinitis and periodontitis: a nationwide population-based study.

The increase in fine dust levels in the atmosphere has been associated with a growth in the incidence of environmental diseases, including allergic rhinitis (AR). Nasal obstruction caused by AR can impact the conditions in the oral cavity. The aim of this study was to determine the association between AR and periodontitis in the Republic of Korea. This study was based on data from the Seventh Korea National Health and Nutrition Examination Survey (KNHANES VII-1, 2016), which was conducted by the Korea Centers for Disease Control and Prevention. The study included 6129 adults older than 19 years. Sociodemographic information and medical variables including history of treatment of periodontitis (HTP) reflecting diagnosis of periodontitis and diagnosis of diseases such as AR were extracted from the data. HTP and AR were reported for 22.81 ± 0.84% (weighted percentage ± standard error) and 15.32 ± 0.63% of the studied population, respectively. A diagnosis of AR was reported for 11.07 ± 1.28% of those with HTP and for 17.55 ± 1.84% of those without HTP. From these, it was inferred that the prevalence of HTP was 1.536-fold higher in the non-AR group than in their counterparts with AR. Significant association was found between AR and HTP among those aged ≤ 64 years and the odds ratio (OR) of AR group for HTP was 0.62 (95% confidence interval:0.44-0.87; P = 0.0057). From this result, it can be inferred that patients diagnosed AR have lower risk of periodontitis.

Association of periodontitis with menopause and hormone replacement therapy: a hospital cohort study using a common data model.

PURPOSE: The present study was designed to compare the incidence of periodontitis according to menopausal status and to investigate the possible effect of hormone replacement therapy (HRT) on periodontitis in postmenopausal women using a common data model (CDM) at a single institution. METHODS: This study involved retrospective cohort data of 950,751 patients from a 20-year database (2001 to 2020) of Ewha Womans University Mokdong Hospital converted to the Observational Medical Outcomes Partnership CDM. One-way analysis of variance models and the χ² test were used to analyze the statistical differences in patient characteristics among groups. A time-dependent Cox regression analysis was used to calculate hazard ratios and 95% confidence intervals, and P values less than 0.05 were considered to indicate statistical significance. RESULTS: Of the 29,729 patients, 1,307 patients were diagnosed with periodontitis and 28,422 patients were not. Periodontitis was significantly more common among postmenopausal patients regardless of HRT status than among the non-menopausal group (P<0.05). Time-dependent Cox regression analysis showed that the postmenopausal patients had a significantly higher chance of having periodontitis than non-menopausal patients (P<0.05), but after adjustment for age, body mass index, and smoking status, the difference between the non-menopausal and post-menopausal HRT-treated groups was insignificant (P=0.140). CONCLUSIONS: Postmenopausal women had a significantly greater risk of periodontitis than non-menopausal women. Additionally, the use of HRT in postmenopausal women could reduce the incidence of periodontitis.

Effects of Ultrasonic Activation on Root Canal Filling Quality of Single-Cone Obturation with Calcium Silicate-Based Sealer.

BACKGROUND: We evaluated the effects of ultrasonic activation on root canal filling quality of the single-cone (SC) obturation technique with calcium silicate sealers and gutta percha cones. METHODS: Thirty-six human single-rooted premolars were obturated with gutta percha and sealer. For the continuous wave (CW) group (n = 12), AH Plus with a continuous wave technique was used. The SC group (n = 12) received EndoSequence BC sealer with a single-cone technique. The SCU (SC with the addition of ultrasonic activation) group (n = 12) received the same treatment. Micro-computed tomography was used to scan the teeth, and the void volume within the root canal was evaluated at the apical, middle, and coronal levels. Then cross-sections were observed under a light microscope and scanning electron microscope (SEM). RESULTS: Void volume was significantly lower in the SCU group than in the CW and SC groups. There were no statistically significant differences between the CW and SC groups. The SCU group had fewer voids than the CW and SC groups in the coronal and middle third areas. Specimens showed no apparent gaps or voids in any group. SEM images revealed both gap-free and gap-containing regions at different levels in all groups. CONCLUSIONS: Single-cone obturation with calcium silicate-based sealers might obtain enhanced filling quality when used with ultrasonic activation.

Correlation analysis of gingival recession after orthodontic treatment in the anterior region: an evaluation of soft and hard tissues.

PURPOSE: The aim of this study was to investigate and identify the main causes of periodontal tissue change associated with labial gingival recession by examining the anterior region of patients who underwent orthodontic treatment. METHODS: In total, 45 patients who had undergone orthodontic treatment from January 2010 to December 2015 were included. Before and after the orthodontic treatment, sectioned images from 3-dimensional digital model scanning and cone-beam computed tomography images in the same region were superimposed to measure periodontal parameters. The initial labial gingival thickness (IGT) and the initial labial alveolar bone thickness (IBT) were measured at 4 mm below the cementoenamel junction (CEJ), and the change of the labial gingival margin was defined as the change of the distance from the CEJ to the gingival margin. Additionally, the jaw, tooth position, tooth inclination, tooth rotation, and history of orthognathic surgery were investigated to determine the various factors that could have affected anterior periodontal tissue changes. RESULTS: The mean IGT and IBT were 0.77±0.29 mm and 0.77±0.32 mm, respectively. The mean gingival recession was 0.14±0.57 mm. Tooth inclination had a significant association with gingival recession, and as tooth inclination increased labially, gingival recession increased by approximately 0.2 mm per 1°. CONCLUSIONS: In conclusion, the IGT, IBT, tooth position, tooth rotation, and history of orthognathic surgery did not affect labial gingival recession. However, tooth inclination showed a significant association with labial gingival recession of the anterior teeth after orthodontic treatment.

Evaluation of prognosis related to compliance with supportive periodontal treatment in patients with chronic periodontitis: a clinical retrospective study.

PURPOSE: The purpose of this study was to evaluate the prognostic effect of patient compliance with supportive periodontal treatment (PC-SPT). Chronic periodontitis patients were classified based on their compliance level, and factors affecting PC-SPT and the prognosis of PC-SPT were investigated. METHODS: This study selected 206 patients who started SPT after receiving periodontal treatment between 2010 and 2012. Patients who continued SPT through February 2016 were included. The patients were classified according to whether they exhibited complete compliance (100% of visits), excellent compliance (≥70% of visits), incomplete compliance (<70% of visits), or non-compliance (only 2 visits). Patient characteristics that could affect PC-SPT, such as age, sex, distance of the clinic from their residence, implantation, and periodontal treatment, were investigated. The number of newly decayed and extracted teeth, alveolar bone level changes around the teeth and implants, and implant removal were examined to evaluate the prognosis of PC-SPT. RESULTS: Sex and the presence of an implant significantly affected PC-SPT. Additionally, the number of newly decayed and extracted teeth and changes in alveolar bone levels around the teeth and implants were significant prognostic factors related to PC-SPT. CONCLUSIONS: PC-SPT in chronic periodontitis patients will help maintain periodontal health and prevent further periodontal disease.

Combining virtual model and cone beam computed tomography to assess periodontal changes after anterior tooth movement.

BACKGROUND: Orthodontic force may affect not only periodontal ligaments, but also the alveoloar bone and the gingiva according to the type of tooth movements. The authors assessed changes in gingival thickness (GT) and alveolar bone thickness (ABT) after orthodontic treatment using a new method. METHODS: This study included 408 teeth (208 central incisors, 200 lateral incisors) from the upper and lower 4 anterior teeth of 52 patients who had completed orthodontic treatment. GT and ABT were measured using virtual casts fabricated from impressions and cone beam computed tomography (CBCT). Two sectioned images of every tooth axis were acquired by partitioning each tooth with a line connecting the midpoint of the incisal edge to the midpoint of the cementoenamel junction in the virtual models and the root apex in CBCT images. After superimposing the two sectioned images, GT and ABT were measured before and after orthodontic tooth movement. Correlations between GT and ABT before and after treatment, and changes in GT and ABT associated with sex, tooth arch, tooth position, orthognathic surgery, and tooth inclination and rotation were assessed. RESULTS: Before orthodontic treatment, GT and ABT were significantly correlated. Patients who underwent orthognathic surgery exhibited an increase in GT thickness compared with those who did not. ABT was significantly decreased in proclined teeth and in rotated teeth. CONCLUSIONS: GT and ABT can be affected by the nature of tooth movement and can be accurately assessed by comparing sectioned CBCT images and virtual models.

Validity assessment of quantitative light-induced fluorescence-digital (QLF-D) for the dental plaque scoring system: a cross-sectional study.

BACKGROUND: The aim of this study was to analyze the correlation between the dental plaque indices measured using quantitative light-induced fluorescence-digital (QLF-D) and conventional clinical indices that assess gingival status. METHODS: From among the patients who visited Ewha Womans University Mokdong Hospital, 33 adults in their 20s who had relatively even teeth were selected for full-mouth QLF-D imaging. The images were used to analyze the QLF-D score and the QLF-D ΔR score. As clinical indices, the gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), and patient hygiene performance (PHP) index were measured. The correlations between the QLF-D score and QLF-D ΔR score and each clinical index were analyzed. Analyses were performed comparing the indices of maxillary and mandibular teeth, the teeth on right and left sides of the mouth, anterior and posterior teeth, and buccal and lingual surfaces of each tooth. Pearson's correlation analysis was conducted (p < 0.05). RESULTS: The mean full-mouth QLF-D score was highly correlated with the GI, BOP, PPD, PHP index (p < 0.01). The mean full-mouth QLF-D score showed the highest correlation with GI (r = 0.749) and the lowest correlation with PPD (r = 0.683). The correlations between the QLF-D score were higher in the mandible than in the maxilla and in the anterior teeth than in the posterior teeth, while no significant differences were seen between the buccal and lingual surfaces of tooth. CONCLUSIONS: This study concluded that the correlations between the plaque indices measured for each tooth surface area using QLF-D and the clinical indices assessed were significantly high, and it allowed objective determination of the gingival status. Therefore, the plaque index measured using QLF-D may be used as an alternative to supplement the shortcomings of conventional clinical indices for educating patients about plaque control and continued patient oral care.

Bone formation of demineralized human dentin block graft with different demineralization time: In vitro and in vivo study.

OBJECTIVE: To evaluate structural and physicochemical characteristics of demineralized human dentin block with increasing demineralization time and to assess new bone formation when onlay grafted at different demineralization times in rat calvaria. STUDY DESIGN: Extracted human permanent teeth were pretreated and demineralized for 10-90 min. Scanning electron microscopy, X-ray diffraction analysis, inductively coupled plasma spectrometry, and energy dispersive X-ray analysis were performed. Demineralized dentin blocks (DDBs) with the representatives of the different demineralization times (10 and 60 min) were implanted in vivo onto rat calvaria (male Sprague-Dawley, n = 20 for each carrier). For controls, collagen sponge and human freeze-dried corticocancellous bone blocks (FDBB) were implanted onto calvaria (n = 20). The rats were sacrificed 2 or 8 weeks postoperatively and evaluated radiographically, histologically, and histomorphometrically. RESULTS: With increasing demineralization time, the surface structure of dentin blocks showed increased number and size of dentinal tubules. Moreover, the organic components increased, whereas inorganic components decreased. Crystallinity decreased sharply between 10 and 30 min demineralization time. In our in vivo study, at both time points, animals with DDBs showed significantly better bone formation than controls (p < 0.05). The DDB/60 group showed significantly increased new bone area and bone density than the DDB/10 group at 8 weeks (p < 0.05), but showed higher resorption that significantly decreased total augmented area compared with the DDB/10 group (p < 0.05). CONCLUSION: DDB increased new bone formation and bone density. Further studies are needed to determine the optimal demineralization time to maximize space maintenance and bone formation of the graft material.

Radiographic study of the distribution of maxillary intraosseous vascular canal in Koreans.

BACKGROUND: This study aimed to investigate the distribution and prevalence of intraosseous loop (anastomosis between posterior superior alveolar artery and infraorbital artery) in Koreans detected on computed tomography (CT) images taken prior to sinus augmentation surgery. METHODS: From the 177 patients who underwent sinus augmentation with lateral approach at Ewha Womans University Department of Implant Dentistry, 284 CT scans were evaluated. The canal height (CH), ridge height (RH), and canal height from the sinus floor (CHS) were measured on para-axial views at the first premolar, first molar, and second molar. The horizontal positions of the bony canals in the lateral wall were also classified. One-way analysis of variance (ANOVA) and t test were used to estimate the statistical differences (p < 0.05). RESULTS: The intraosseous loops were detected in 92 CT scans (32 %). The mean vertical height of the bony canals from the alveolar crest (CH) was 23.45 ± 2.81, 15.92 ± 2.65, and 16.61 ± 2.92 mm at the second premolar, first molar, and second molar, respectively. In the horizontal positions of the bony canals, intraosseous type was the most predominant. The canal heights more than 15 mm and less than 17 mm were most prevalent (33.7 %) and those under 13 mm were 12.0 %. CONCLUSIONS: The radiographic findings in this study could be used to decide the lateral osteotomy line avoiding potential vascular complication. However, only one third of the canals could be detected in CT scans; a precaution should be taken for the possibility of severe bleeding during lateral osteotomy.

Histomorphometric evaluation of onlay freeze-dried block bone and deproteinized bovine bone with collagen in rat.

The aim of this study was to evaluate the effect of human freeze-dried bone block (FDBB) and deproteinized bovine bone with collagen (DBBC) on bone formation when applied as an onlay graft in rat calvariums. Thirty male Sprague-Dawley rats received collagen sponge (control), FDBB, or DBBC onlay grafts trimmed into 8-mm disks measuring 4-mm height. Each graft was secured onto the calvarium surface using horizontal mattress sutures. Rats in each group were killed at 2 (n=5) or 8 (n=5) weeks postoperatively for histologic and histomorphometric analysis. The total augmented area (mm2), new bone area (mm2), and bone density (%) were measured. The FDBB and DBBC groups showed significantly more new bone formation and bone density than the control group at 2 and 8 weeks. The increased new bone area was significantly greater in the FDBB group than in the DBBC group (p<0.05). The total augmented area was significantly higher in the FDBB and DBBC groups at 2 and 8 weeks than in the control group (p<0.05), and at 8 weeks, the area was significantly decreased in the DBBC group compared to that in the FDBB group and the area at 2 weeks (p<0.05). Within the limitations of the present study, we concluded that onlay FDBB and DBBC grafts caused new bone formation through an osteoconductive mechanism. In addition, compared to FDBB, DBBC had less capacity to form new bone and maintain the space.

Effects of block bone substitutes loaded with Escherichia Coli-produced recombinant human bone morphogenetic protein-2 on space maintenance and bone formation in rat calvarial onlay model.

We aimed to evaluate the effects of onlay-type grafted human freeze-dried corticocancellous bone block (FDBB) and deproteinized bovine bone with collagen (DBBC) loaded with Escherichia coli-produced recombinant human bone morphogenetic protein-2 (ErhBMP-2) on space maintenance and new bone formation in rat calvaria. Collagen sponge (CS), FDBB, or DBBC disks (8×4 mm) with ErhBMP-2 (2.5 µg) were implanted onto the calvaria of male Sprague-Dawley rats, whereas CS with buffer was implanted onto the calvaria as controls (n=20/carrier). Rats were killed at 2 or 8 weeks post-surgery for histologic and histomorphometric analyses; total augmented area, new bone area, and bone density were evaluated. At both time-points, all ErhBMP-2 groups showed significantly higher new bone area and bone density than the control group (p<0.05). ErhBMP-2/FDBB and ErhBMP-2/DBBC groups showed significantly higher total augmented area than ErhBMP-2/CS group (8 weeks), and ErhBMP-2/FDBB group showed significantly higher new bone area and bone density than ErhBMP-2/DBBC group (p<0.05). ErhBMP-2/CS group showed the highest bone density (p<0.05). Combining ErhBMP-2 with FDBB or DBBC could significantly improve onlay graft outcomes, by new bone formation and bone density increase. Moreover, onlay-grafted FDBB and DBBC with ErhBMP-2 could be an alternative to autogenous block onlay bone graft.

Rapid bone regeneration by Escherichia coli-derived recombinant human bone morphogenetic protein-2 loaded on a hydroxyapatite carrier in the rabbit calvarial defect model.

BACKGROUND: The aim of this study was to determine the osteoconductivity of hydroxyapatite particles (HAP) as a carrier for Escherichia coli-derived recombinant human bone morphogenetic protein-2 (ErhBMP-2). Two 8-mm diameter bicortical calvarial defects were created in each of 20 rabbits. One of each pair of defects was randomly assigned to be filled with HAP only (HAP group) or ErhBMP-2 loaded HAP (ErhBMP-2/HAP group), while the other defect was left untreated (control group). The animals were killed after either 2 weeks (n = 10) or 8 weeks (n = 10) of healing, and histological, histomorphometric, and tomographic analyses were performed. RESULTS: All experimental sites showed uneventful healing during the postoperative healing period. In both histomorphometric and tomographic analyses, the new bone area or volume of the ErhBMP-2/HAP group was significantly greater than that of the HAP and control groups at 2 weeks (p < 0.05). However, at 8 weeks, no significant difference in new bone area or volume was observed between the ErhBMP-2/HAP and HAP groups. The total augmented area or volume was not significantly different between the ErhBMP-2/HAP and HAP groups at 2 and 8 weeks. CONCLUSIONS: Combining ErhBMP-2 with HAP could significantly promote rapid initial new bone formation. Moreover, HAP graft could increase new bone formation and space maintenance, therefore it might be one of the effective carriers of ErhBMP-2.

Immobilization of murine anti-BMP-2 monoclonal antibody on various biomaterials for bone tissue engineering.

Biomaterials are widely used as scaffolds for tissue engineering. We have developed a strategy for bone tissue engineering that entails application of immobilized anti-BMP-2 monoclonal antibodies (mAbs) to capture endogenous BMPs in vivo and promote antibody-mediated osseous regeneration (AMOR). The purpose of the current study was to compare the efficacy of immobilization of a specific murine anti-BMP-2 mAb on three different types of biomaterials and to evaluate their suitability as scaffolds for AMOR. Anti-BMP-2 mAb or isotype control mAb was immobilized on titanium (Ti) microbeads, alginate hydrogel, and ACS. The treated biomaterials were surgically implanted in rat critical-sized calvarial defects. After 8 weeks, de novo bone formation was assessed using micro-CT and histomorphometric analyses. Results showed de novo bone regeneration with all three scaffolds with immobilized anti-BMP-2 mAb, but not isotype control mAb. Ti microbeads showed the highest volume of bone regeneration, followed by ACS. Alginate showed the lowest volume of bone. Localization of BMP-2, -4, and -7 antigens was detected on all 3 scaffolds with immobilized anti-BMP-2 mAb implanted in calvarial defects. Altogether, these data suggested a potential mechanism for bone regeneration through entrapment of endogenous BMP-2, -4, and -7 proteins leading to bone formation using different types of scaffolds via AMOR.

Anterior maxillary defect reconstruction with a staged bilateral rotated palatal graft.

PURPOSE: In the anterior maxilla, hard and soft tissue augmentations are sometimes required to meet esthetic and functional demands. In such cases, primary soft tissue closure after bone grafting procedures is indispensable for a successful outcome. This report describes a simple method for soft tissue coverage of a guided bone regeneration (GBR) site using the double-rotated palatal subepithelial connective tissue graft (RPSCTG) technique for a maxillary anterior defect. METHODS: We present a 60-year-old man with a defect in the anterior maxilla requiring hard and soft tissue augmentations. The bone graft materials were filled above the alveolar defect and a titanium-reinforced nonresorbable membrane was placed to cover the graft materials. We used the RPSCTG technique to achieve primary soft tissue closure over the graft materials and the barrier membrane. Additional soft tissue augmentation using a contralateral RPSCTG and membrane removal were simultaneously performed 7 weeks after the stage 1 surgery to establish more abundant soft tissue architecture. RESULTS: Flap necrosis occurred after the stage 1 surgery. Signs of infection or suppuration were not observed in the donor or recipient sites after the stage 2 surgery. These procedures enhanced the alveolar ridge volume, increased the amount of keratinized tissue, and improved the esthetic profile for restorative treatment. CONCLUSIONS: The use of RPSCTG could assist the soft tissue closure of the GBR sites because it provides sufficient soft tissue thickness, an ample vascular supply, protection of anatomical structures, and patient comfort. The treatment outcome was acceptable, despite membrane exposure, and the RPSCTG allowed for vitalization and harmonization with the recipient tissue.

Impact of different synthetic bone fillers on healing of extraction sockets: an experimental study in dogs.

OBJECTIVES: The objective of this study was to elucidate the socket healing process and biodegradation of incorporating synthetic bone fillers followed by grafting of the fresh extraction socket. MATERIALS AND METHODS: Third premolars in four quadrants of eight beagle dogs were extracted and randomly treated with either one of hydroxyapatite (HA), biphasic calcium phosphate (BCP), ß-tricalcium phosphate (ß-TCP), or no graft (C). Histologic observations and histomorphometric analysis at three zones (apical, middle, and coronal) of the socket were performed. Socket area (S) and the proportions of newly formed bone (%NB), residual biomaterials (%RB), and fibrovascular connective tissue (%FCT) at 2, 4, and 8 weeks were measured. The numbers of osteoclast-like multinucleated cells (No.OC) were also determined at the three zones. RESULTS: %NB was significantly higher in control group compared with the grafted groups at all healing periods. %NB of HA and BCP increased with time, whereas %RB showed different patterns that decreased in BCP, unlike the minimal change observed in HA. %NB of ß-TCP showed smallest portion compared with other grafted groups at 2 and 4 weeks, however, significantly increased at 8 weeks. %RB of ß-TCP was less than HA and BCP at all healing periods. Numbers of multinucleated cells were greater in BCP and ß-TCP, followed by HA and smallest in control group. CONCLUSIONS: Within the limit of this study, bone formation of the extraction socket was delayed in the sockets grafted with synthetic bone fillers and showed different healing process according to the biodegradation patterns.

Effects of adjunctive daily phototherapy on chronic periodontitis: a randomized single-blind controlled trial.

PURPOSE: The purpose of this randomized single-blind controlled trial was to elucidate the clinical and antimicrobial effects of daily phototherapy (PT) as an adjunct to scaling and root planing (SRP) in patients with chronic periodontitis. METHODS: The study was conducted from December 2013 to May 2014 at Ewha Womans University Mokdong Hospital, Seoul, Korea. Forty-one patients with mild to moderate chronic periodontitis were randomly divided into two therapeutic groups in a 1:1 ratio: SRP+PT and SRP (control) groups. All participants underwent full-mouth SRP. PT was performed thrice a day for a month by using electric toothbrushes with embedded light-emitting diodes. Plaque index, gingival index, probing pocket depth (PPD), clinical attachment level (CAL), and bleeding on probing were assessed before (baseline) and four weeks after (follow-up) the treatment. Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis, Tannerella forsythia, Treponema denticola, Prevotella intermedia, Fusobacterium nucleatum, Parvimonas micra, Campylobacter rectus, Eikenella corrodens, Streptococcus mutans, and Streptococcus sobrinus levels were detected by a real-time polymerase chain reaction at the same points in time. RESULTS: The clinical parameters improved in both the groups. At the follow-up assessment, PPD was significantly decreased in the SRP+PT group (P=0.00). Further, PPD and CAL showed significantly greater changes in the SRP+PT group than in the SRP group (PPD, P=0.03; CAL, P=0.04). P. gingivalis and T. forsythia levels decreased in this group, but no significant intergroup differences were noted. CONCLUSIONS: Adjunctive PT seems to have clinical benefits, but evidence of its antimicrobial effects is not sufficient. Long-term studies are necessary to develop the most effective PT protocol and compare the effectiveness of PT with and without exogenous photosensitizers.

The effect of varying the particle size of beta tricalcium phosphate carrier of recombinant human bone morphogenetic protein-4 on bone formation in rat calvarial defects.

BACKGROUND: Beta tricalcium phosphate (beta-TCP) has been developed as one of the carriers of recombinant human bone morphogenetic protein (rhBMP). However, it is not known whether the particle size of beta-TCP is related to its resorption rate and the degree of bone formation. The purpose of this study was to evaluate the effect of using beta-TCP with different particle sizes on the ability of rhBMP-4 to enhance bone formation in the rat calvarial defect model. METHODS: Calvarial, 8-mm-diameter, critical-size defects were created in 100 male Sprague-Dawley rats. Five groups of 20 animals each received either rhBMP-4 (2.5 microg) using beta-TCP with a particle size of 50 to 150 microm, rhBMP-4 (2.5 microg) using beta-TCP with a particle size of 150 to 500 microm, a beta-TCP control with a particle size of 50 to 150 microm, a beta-TCP control with a particle size of 150 to 500 microm, or a sham-surgery control, respectively, and were evaluated by measuring their histologic and histometric parameters following a 2- and 8-week healing interval. RESULTS: There were no significant differences in the defect closure, new bone area, or augmented area between either the two rhBMP-4/beta-TCP groups or between the two beta-TCP control groups at 2 and 8 weeks. CONCLUSIONS: rhBMP-4 combined with either small- or large-particle beta-TCP had a significant effect on the induction of bone formation compared to either a small- or large-particle beta-TCP control or a sham-surgery control. Within the parameters of this study, varying the particle size of beta-TCP did not seem to have a significant effect on bone formation.

Effects of chitosan on human periodontal ligament fibroblasts in vitro and on bone formation in rat calvarial defects.

BACKGROUND: The purpose of this study was to evaluate the effect of chitosan on human periodontal ligament fibroblasts (hPDLF) in vitro and on bone formation in rat calvarial defects in vivo. METHODS: Fibroblast populations were obtained from individuals with a healthy periodontium and cultured in alpha minimum essential medium (MEM) for the control group. For the experimental groups, cells were cultured in alpha-MEM containing chitosan at concentrations of 0.01, 0.1, 1, or 2 mg/ml. The 3-(4,5-dimethyl-thiazole-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay, reverse transcription-polymerase chain reaction (RT-PCR) and the assay of alkaline phosphatase (ALPase) activity were performed. Eight mm calvarial critical-sized defects were created in 30 male Sprague-Dawley rats. The animals were divided into three groups of 10 animals each. The defects were treated with either chitosan/absorbable collagen sponge (ACS) or ACS alone in the experimental groups or were left untreated (surgical controls). The animals were sacrificed at 2 or 8 weeks post-surgery and the treatment outcomes were evaluated using histological and histomorphometric parameters. RESULTS: The chitosan-induced proliferative responses of the hPDLF reached a plateau at a concentration of 0.1 mg/ml (P <0.05). When the hPDLF were stimulated with 0.1 mg/ml chitosan, both the mRNA expression of type I collagen and the ALP activity were significantly up-regulated (P <0.05). The surgical implantation of chitosan/ACS enhanced the new bone formation at 8 weeks post-surgery and the amount of new bone formation of the chitosan/ACS group was significantly greater than that of both the ACS alone group and the surgical control group (P <0.01). The new bone area and defect closure in the chitosan/ACS group were significantly greater than those in the ACS control and sham surgery control groups at 8 weeks (P <0.01). However, the chitosan/ ACS group exhibited significantly less bone density than both the ACS control and the sham surgery control group at 8 weeks (P <0.01). CONCLUSIONS: Chitosan (0.1 mg/ml) enhanced the type I collagen synthesis and facilitated the differentiation into osteogenic cells. Chitosan reconstituted with ACS has a significant potential to accelerate the regeneration of bone in rat calvarial critical size defects.

Effect of recombinant human bone morphogenetic protein-4 dose on bone formation in a rat calvarial defect model.

BACKGROUND: Bone morphogenetic proteins (BMPs) are being evaluated for periodontal and bone regenerative therapy. The objective of this study was to evaluate the effect of recombinant human bone morphogenetic protein-4 (rhBMP-4) dose on local bone formation in a rat calvaria defect model. METHODS: Calvarial, 8 mm diameter, critical-size osteotomy defects were created in 140 male Sprague-Dawley rats. Seven groups of 20 animals each received either 1) rhBMP-4 (2.5 microg) in an absorbable collagen sponge (ACS) carrier, 2) rhBMP-4 (5 microg)/ACS, 3) rhBMP-4 (2.5 microg) in a beta-tricalcium phosphate (beta-TCP) carrier, 4) rhBMP-4 (5 microg)/beta-TCP, 5) ACS or 6) beta-TCP carrier controls, or 7) a sham-surgery control, and were evaluated by histologic and histometric parameters following a 2- or 8-week healing interval (10 animals/group/healing interval). RESULTS: Surgical implantation of rhBMP-4/ACS and rhBMP-4/beta-TCP resulted in enhanced local bone formation at both 2 and 8 weeks. Within the dose range examined, rhBMP-4 did not exhibit an appreciable dose-dependent response. Defect closure was not significantly different between the rhBMP-4/ACS and rhBMP-4/beta-TCP groups. New bone area of the rhBMP-4/ beta-TCP group was significantly greater than that of the rhBMP-4/ ACS group; however, bone density in the rhBMP-4/ACS group was significantly greater than that in the rhBMP-4/beta-TCP group at 8 weeks (P < 0.05). CONCLUSIONS: rhBMP-4 combined with ACS or beta-TCP has a significant potential to induce bone formation in the rat calvaria defect model. Within the selected rhBMP-4 dose range and observation interval, there appeared to be no meaningful differences in bone formation.

Inhibitory effects of green tea polyphenol (-)-epigallocatechin gallate on the expression of matrix metalloproteinase-9 and on the formation of osteoclasts.

BACKGROUND: Alveolar bone resorption is a characteristic feature of periodontal diseases and involves the removal of both the mineral and organic constituents of the bone matrix, which is caused by either multinucleated osteoclast cells or matrix metalloproteinases (MMPs). The gram-negative bacterium, Porphyromonas gingivalis has been reported to stimulate the activity and expression of several groups of MMPs, whereas (-)-epigallocatechin gallate (EGCG), the main constituent of green tea polyphenols, has been reported to have inhibitory effects on the activity and expression of MMPs. OBJECTIVES: In the present study, we investigated the effects of the green tea polyphenol, EGCG, on the gene expression of osteoblast-derived MMP-2, -9 and -13, stimulated by P. gingivalis, and on the formation of osteoclasts. METHODS: The effect of EGCG on the gene expression of MMPs was examined by treating mouse calvarial primary osteoblastic cells with EGCG (20 microM) in the presence of sonicated P. gingivalis extracts. The transcription levels of MMP-2, -9 and -13 were assessed by reverse transcription-polymerase chain reaction (RT-PCR). The effect of EGCG on osteoclast formation was confirmed by tartrate-resistant acid phosphatase (TRAP) staining in a co-culture system of mouse bone marrow cells and calvarial primary osteoblastic cells. RESULTS: Treatment with the sonicated P. gingivalis extracts stimulated the expression of MMP-9 mRNA and this effect was significantly reduced by EGCG, whereas the transcription levels of MMP-2 and MMP-13 were not affected by either the sonicated P. gingivalis extracts or EGCG. In addition, EGCG significantly inhibited osteoclast formation in the co-culture system at a concentration of 20 microM. CONCLUSIONS: These findings suggest that EGCG may prevent the alveolar bone resorption that occurs in periodontal diseases by inhibiting the expression of MMP-9 in osteoblasts and the formation of osteoclasts.