Nobuo Yoshinari

Osteoprotegerin-Deficient Male Mice as a Model for Severe Alveolar Bone Loss: Comparison With RANKL-Overexpressing Transgenic Male Mice

Periodontitis, an inflammatory disease of periodontal tissues, is characterized by excessive alveolar bone resorption. An increase in the receptor activator of nuclear factor-κB ligand (RANKL) to osteoprotegerin (OPG) ratio is thought to reflect the severity of periodontitis. Here, we examined alveolar bone loss in OPG-deficient (OPG(-/-)) mice and RANKL-overexpressing transgenic (RANKL-Tg) mice. Alveolar bone loss in OPG(-/-) mice at 12 weeks was significantly higher than that in RANKL-Tg mice. OPG(-/-) but not RANKL-Tg mice exhibited severe bone resorption especially in cortical areas of the alveolar bone. An increased number of osteoclasts was observed in the cortical areas in OPG(-/-) but not in RANKL-Tg mice. Immunohistochemical analyses showed many OPG-positive signals in osteocytes but not osteoblasts. OPG-positive osteocytes in the cortical area of alveolar bones and long bones were abundant in both wild-type and RANKL-Tg mice. This suggests the resorption in cortical bone areas to be prevented by OPG produced locally. To test the usefulness of OPG(-/-) mice as an animal model for screening drugs to prevent alveolar bone loss, we administered an antimouse RANKL antibody or risedronate, a bisphosphonate, to OPG(-/-) mice. They suppressed alveolar bone resorption effectively. OPG(-/-) mice are useful for screening therapeutic agents against alveolar bone loss.

Salivary pathogen and serum antibody to assess the progression of chronic periodontitis: a 24-mo prospective multicenter cohort study

BACKGROUND AND OBJECTIVE A diagnosis of periodontitis progression is presently limited to clinical parameters such as attachment loss and radiographic imaging. The aim of this multicenter study was to monitor disease progression in patients with chronic periodontitis during a 24-mo follow-up program and to evaluate the amount of bacteria in saliva and corresponding IgG titers in serum for determining the diagnostic usefulness of each in indicating disease progression and stability. MATERIAL AND METHODS A total of 163 patients with chronic periodontitis who received trimonthly follow-up care were observed for 24 mo. The clinical parameters and salivary content of Porphyromonas gingivalis, Prevotella intermedia and Aggregatibacter actinomycetemcomitans were assessed using the modified Invader PLUS assay, and the corresponding serum IgG titers were measured using ELISA. The changes through 24 mo were analyzed using cut-off values calculated for each factor. One-way ANOVA or Fishers exact test was used to perform between-group comparison for the data collected. Diagnostic values were calculated using Fishers exact test. RESULTS Of the 124 individuals who completed the 24-mo monitoring phase, 62 exhibited periodontitis progression, whereas 62 demonstrated stable disease. Seven patients withdrew because of acute periodontal abscess. The ratio of P. gingivalis to total bacteria and the combination of P. gingivalis counts and IgG titers against P. gingivalis were significantly related to the progression of periodontitis. The combination of P. gingivalis ratio and P. gingivalis IgG titers was significantly associated with the progression of periodontitis (p = 0.001, sensitivity = 0.339, specificity = 0.790). CONCLUSIONS It is suggested that the combination of P. gingivalis ratio in saliva and serum IgG titers against P. gingivalis may be associated with the progression of periodontitis.

Prevalence and risk factors for peri-implant diseases in Japanese adult dental patients

We investigated the prevalences and risk factors for peri-implant diseases in Japanese adult dental patients attending a follow-up visit at dental hospitals or clinics as part of their maintenance program. This cross-sectional multicenter study enrolled patients with dental implants who attended regular check-ups as part of a periodontal maintenance program during the period from October 2012 through September 2013. Patients with implants with at least 3 years of loading time were included in the study. The condition of peri-implant tissue was examined and classified into the following categories: healthy, peri-implant mucositis, and peri-implantitis. Patients were also evaluated for implant risk factors. A total of 267 patients (110 men, 157 women; mean age: 62.5 ± 10.7 years) were analyzed. The prevalence of patient-based peri-implant mucositis was 33.3% (n = 89), and the prevalence of peri-implantitis was 9.7% (n = 26). Poor oral hygiene and a history of periodontitis were strong risk factors for peri-implant disease. The present prevalences were lower than those previously reported. The quality of periodontal therapy before and after implant installation and patient compliance and motivation, as indicated by plaque control level, appear to be important in maintaining peri-implant tissue health.

The short-term effects of various oral care methods in dependent elderly: Comparison between toothbrushing, tongue cleaning with sponge brush and wiping on oral mucous membrane by chlorhexidine

OBJECTIVES To explore the short-term effects from toothbrushing, tongue cleaning with sponge brush and wiping on oral mucous membrane by chlorhexidine. BACKGROUND Numerous reports have been seen in recent years proving the effectiveness of mouth cleaning with a toothbrush for the prevention of respiratory infections among the dependent elderly. However, the short-term effects from each oral care method have not yet been clarified. Hence, an investigation was conducted by having each subject independently perform various oral care methods for five consecutive days. MATERIALS AND METHODS The subjects consisted of 12 assistance-dependent elderly who have difficulties with tooth brushing by themselves, have 10 or more residual teeth and are not yet using plate dentures. After the pre-intervention examination, each of the following oral care methods were performed on the same subject on an approximately three week basis: 1) Tooth brushing 2) Tongue cleaning with sponge brush 3) Wiping on oral mucous with sponge brush by chlorhexidine. Each method was performed independently, once a day for 5 consecutive days and the subjects were reexamined on the sixth day for comparative verification. RESULTS Consequently, toothbrushing decreased the plaque index and gingival index significantly and an improvement of oral malodour was also acknowledged (p < 0.01). Tongue cleaning with a sponge brush decreased the tongue coat score significantly (p < 0.05) and oral malodour was also improved (p < 0.01). Wiping on oral mucous with a sponge brush soaked in chlorhexidine significantly decreased opportunistic infections in the pharynx region (p < 0.05). CONCLUSIONS It was suggested that the use of not only a toothbrush but also chlorhexidine gluconate may be indicated for dependent elderly people in whom pathogens of opportunistic infection are detected.

Assessing the progression of chronic periodontitis using subgingival pathogen levels: a 24-month prospective multicenter cohort study

BackgroundThe diagnosis of the progression of periodontitis presently depends on the use of clinical symptoms (such as attachment loss) and radiographic imaging. The aim of the multicenter study described here was to evaluate the diagnostic use of the bacterial content of subgingival plaque recovered from the deepest pockets in assessing disease progression in chronic periodontitis patients.MethodsThis study consisted of a 24-month investigation of a total of 163 patients with chronic periodontitis who received trimonthly follow-up care. Subgingival plaque from the deepest pockets was recovered and assessed for bacterial content of Porphyromonas gingivalis, Prevotella intermedia, and Aggregatibacter actinomycetemcomitans using the modified Invader PLUS assay. The corresponding serum IgG titers were measured using ELISA. Changes in clinical parameters were evaluated over the course of 24 months. The sensitivity, specificity, and prediction values were calculated and used to determine cutoff points for prediction of the progression of chronic periodontitis.ResultsOf the 124 individuals who completed the 24-month monitoring phase, 62 exhibited progression of periodontitis, whereas 62 demonstrated stable disease. The P. gingivalis counts of subgingival plaque from the deepest pockets was significantly associated with the progression of periodontitis (p < 0.001, positive predictive value = 0.708).ConclusionsThe P. gingivalis counts of subgingival plaque from the deepest pockets may be associated with the progression of periodontitis.

Effects of the vertical projection angle in intraoral radiography on the detection of furcation involvement of the mandibular first molar

ObjectivesTo investigate the effects of vertical projection angle alterations in intraoral radiography on the detection of furcation defects in the mandibular first molar, and to clarify the possible cause of variations in detectability.MethodsFive bilateral first molars of dried mandibles were used as a furcation disease model. Simulated defects of different depths were created in a stepwise manner, and intraoral radiographs were taken using different vertical angles of the X-ray beam. A total of 858 radiographs were incorporated into the statistical analysis. The simulated defects were divided into four groups according to the depths acquired from cone-beam computed tomography examinations. The detectability of the extent of each loss of bone was calculated as the area under the curve using a receiver-operating characteristic analysis.ResultsSmall defects were less detectable than larger defects, and the upper angle (20°) resulted in the best detectability. The detectability of larger defects was high throughout all the angles, with the exception of extremely low angles.ConclusionsDiagnostic accuracy was affected by the vertical angle of the X-ray beam. An angle that avoids the cortical bone wall would improve the ability to detect and diagnose small defects.

Treatment of OPG-deficient mice with WP9QY, a RANKL-binding peptide, recovers alveolar bone loss by suppressing osteoclastogenesis and enhancing osteoblastogenesis

Osteoblasts express two key molecules for osteoclast differentiation, receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG), a soluble decoy receptor for RANKL. RANKL induces osteoclastogenesis, while OPG inhibits it by blocking the binding of RANKL to RANK, a cellular receptor of RANKL. OPG-deficient (OPG–/–) mice exhibit severe alveolar bone loss with enhanced bone resorption. WP9QY (W9) peptide binds to RANKL and blocks RANKL-induced osteoclastogenesis. W9 is also reported to stimulate bone formation in vivo. Here, we show that treatment with W9 restores alveolar bone loss in OPG–/–mice by suppressing osteoclastogenesis and enhancing osteoblastogenesis. Administration of W9 or risedronate, a bisphosphonate, to OPG–/–mice significantly decreased the osteoclast number in the alveolar bone. Interestingly, treatment with W9, but not risedronate, enhanced Wnt/β-catenin signaling and induced alveolar bone formation in OPG–/–mice. Expression of sclerostin, an inhibitor of Wnt/β-catenin signaling, was significantly lower in tibiae of OPG–/–mice than in wild-type mice. Treatment with risedronate recovered sclerostin expression in OPG–/–mice, while W9 treatment further suppressed sclerostin expression. Histomorphometric analysis confirmed that bone formation-related parameters in OPG–/–mice, such as osteoblast number, osteoblast surface and osteoid surface, were increased by W9 administration but not by risedronate administration. These results suggest that treatment of OPG–/–mice with W9 suppressed osteoclastogenesis by inhibiting RANKL signaling and enhanced osteoblastogenesis by attenuating sclerostin expression in the alveolar bone. Taken together, W9 may be a useful drug to prevent alveolar bone loss in periodontitis.

Porphyromonas gingivalis hydrogen sulfide enhances methyl mercaptan-induced pathogenicity in mouse abscess formation

Porphyromonas gingivalis produces hydrogen sulfide (H2S) from l-cysteine. However, the role of H2S produced by P. gingivalis in periodontal inflammation is unclear. In this study, we identified the enzyme that catalyses H2S production from l-cysteine and analysed the role of H2S using a mouse abscess model. The enzyme identified was identical to methionine γ-lyase (PG0343), which produces methyl mercaptan (CH3SH) from l-methionine. Therefore, we analysed H2S and CH3SH production by P. gingivalis W83 and a PG0343-deletion mutant (ΔPG0343) with/without l-cysteine and/or l-methionine. The results indicated that CH3SH is produced constitutively irrespective of the presence of l-methionine, while H2S was greatly increased by both P. gingivalis W83 and ΔPG0343 in the presence of l-cysteine. In contrast, CH3SH production by ΔPG0343 was absent irrespective of the presence of l-methionine, and H2S production was eliminated in the absence of l-cysteine. Thus, CH3SH and H2S production involves different substrates, l-methionine or l-cysteine, respectively. Based on these characteristics, we analysed the roles of CH3SH and H2S in abscess formation in mice by P. gingivalis W83 and ΔPG0343. Abscess formation by P. gingivalis W83, but not ΔPG0343, differed significantly in the presence and absence of l-cysteine. In addition, the presence of l-methionine did not affect the size of abscesses generated by P. gingivalis W83 and ΔPG0343. Therefore, we conclude that H2S produced by P. gingivalis does not induce inflammation; however, H2S enhances inflammation caused by CH3SH. Thus, these results suggest the H2S produced by P. gingivalis plays a supportive role in inflammation caused by methionine γ-lyase.

Contents, Vol. 59, 2013

Clinical Section M. Burtscher, Innsbruck G. Del Giudice, Siena V.C. Emery, Guildford J.D. Erusalimsky, Cardiff L. Fontana, St. Louis, Mo. J.J. Goronzy, Stanford, Calif. U. Granacher, Potsdam S. Gravenstein, Cleveland, Ohio F. Kronenberg, Innsbruck T.F. Lue, San Francisco, Calif. A.B. Maier, Amsterdam J. Olshansky, Chicago, Ill. T.M. Stulnig, Vienna J. Tao, Guangzhou D.C. Willcox, Ginowan D. Ziegler, Düsseldorf Behavioural Science Section K.J. Anstey, Acton, A.C.T. L. Clare, Bangor X.-Q. Dong, Chicago, Ill. J.D. Henry, St. Lucia, Qld. T. Hess, Raleigh, N.C. S.M. Hofer, Victoria, B.C. C.A. Hoppmann, Vancouver, B.C. D.C. Park, Dallas, Tex. R. Schwendimann, Basel

Effect of Periapical Lesion on Periodontal Lesion in Rats

今回の実験では, ラットの根尖病変が歯周病変に及ぼす影響を組織学的および組織形態計測学的に検索した。ラットを処置方法の違いによって, A, B, C群およびa, b, c群に分けた。全ての動物では, 上顎臼歯の歯間部にナイロン糸を挿入した。A, B, C群では, ナイロン糸挿入後から, それぞれ4, 8, 12週でその歯周組織を観察した。さらに, a群では, ナイロン糸挿入と同時に臼歯を露髄し, 処置後4週で観察した。また, b, c群では, ナイロン糸挿入して4, 8週後に臼歯を露髄し, 露髄後4週で観察した。組織学的には, A, B, C群では, 歯間部の歯周組織には炎症病変が成立した。しかし, その歯周病変は根尖部および根分岐部の歯周組織に波及することはなかった。a群では, 歯間部の歯周組織には, A群のものとほぼ同様の炎症病変がみられた。また, 根尖部にも炎症病変が認められた。b, c群では, 歯間部の歯周組織には, B, C群のものよりも強い炎症がみられた。また, 根尖部には炎症病変が成立し, 根分岐部にも炎症が認められた。しかし, 歯間部と根尖部の炎症は組織学的につながらなかった。組織形態計測学的には, A群とa群のセメントエナメル境から歯槽骨の頂点までの距離の間では, 有意な差はみられなかった。しかし, b, c群の距離はそれぞれB, C群のものに比べて有意に大きかった。本実験の結果, 歯周病変が存在するとき, 根尖病変が生じると, その歯周病変は悪化することが推測された。