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Aim To compare marginal bone level changes around immediately placed and immediately provisionalized implants with immediately placed and delayed provisionalized implants in the aesthetic region after five years of function. Materials and Methods Forty patients with a failing tooth in the maxillary anterior region were randomly assigned immediate implant placement with immediate (Group A: n = 20) or delayed (Group B: n = 20) provisionalization. Definitive crown placement occurred three months after provisionalization. The primary outcomes were changes in marginal bone level. In addition, survival rates, buccal bone thickness, soft peri‐implant tissues, aesthetics and patient‐reported outcomes were assessed. Results After 5 years, the mean mesial and distal marginal bone level changes were 0.71 ± 0.68 mm and 0.71 ± 0.71 mm, respectively, in group A and 0.49 ± 0.52 mm and 0.54 ± 0.64 mm, respectively, in group B; the difference between the groups was not significant (p = .305 and p = .477, respectively). Implant and restoration survivals were 100%. No clinically relevant differences in buccal bone thickness or in mid‐facial peri‐implant mucosal level, aesthetic and patient outcomes were observed. Conclusions The mean marginal bone level changes following immediate implant placement and provisionalization were comparable with immediate implant placement and delayed provisionalization. (www.isrctn.com: ISRCTN57251089 and www.trialregister.nl: NL8255).

Diabetes represents a challenge in implant therapy because hyperglycemia may negatively affect bone regeneration, directly compromising clinical outcomes and increasing clinical failures. The aim of this retrospective study is to analyse the prognostic significance of HbA1c levels in patients undergoing implant placement associated with horizontal guided bone regeneration. Thirty-four patients were divided into 3 groups according to their HbA1c levels: nondiabetic normoglycemic patients ( HbA 1 c < 5.7 % ), nondiabetic hyperglycemic patients ( HbA 1 c < 6.5 % ), and controlled diabetic patients ( HbA 1 c < 7 % ). Primary outcomes were dimensional changes in height (VDH) and width (DW) of the peri-implant defect. Secondary outcomes were evaluations of periodontal parameters of adjacent tooth sites, wound healing, marginal bone loss (MBL), and survival and success rates. At T 1 (6 months), mean VDH values in groups 1, 2, and 3 were, respectively, 0.07, 0.5, and 0.25 mm. Mean DW values in those same groups were, respectively, 0.07, 0.38, and 0.33 mm. HbA1c levels were not statistically related to VDH and DW values at T 1 . No statistically significant differences were observed in MBL between groups ( p = 0.230 ). Implant survival and success rates were, respectively, 98% and 96%. Simultaneous guided bone regeneration is a feasible procedure for the treatment of horizontal bone deficiencies in controlled diabetic patients.

Background Resolution and prevention of peri‐implant mucositis are a key in preventing peri‐implantitis. This case–control study aims to assess the modifying effect of a deep mucosal tunnel (DMT) on the induction and resolution phases of experimental peri‐implant mucositis. Methods Nineteen subjects with a tissue level implant were assigned to cases (DMT, depth ≥3 mm) or controls (shallow mucosal tunnel ≤1 mm, SMT). Subjects underwent a standard experimental peri‐implant mucositis protocol characterized by an oral hygiene optimization phase, a 3‐week induction phase using an acrylic stent to prevent self‐performed oral hygiene at the experimental implant, and a 3 + 2 weeks resolution phase. Modified plaque (mPI), gingival index (mGI) and peri‐implant sulcus fluid IL‐1β concentrations were measured over time. Differences between DMT and SMT were assessed with the Mann–Whitney test. Results Modified plaque index and mGI increased in parallel during the induction phase. After resumption of oral hygiene practice, mPI and mGI resolved towards baseline values in the SMT group. In DMT, mPI and mGI values diverged: plaque resolved but resolution of inflammation was delayed and of smaller magnitude during the first 3 weeks after resumption of oral hygiene. IL‐1β concentrations were significantly higher in DMT at 21 days (end of induction) and during the resolution phase corroborating the clinical findings. Removal of the crown and submucosal professional cleaning were needed to revert mGI to baseline values in DMT implants. Conclusions The depth of the mucosal tunnel modifies the resolution of experimental peri‐implant mucositis at transmucosal implants. This observation raises important questions on the effectiveness of self‐performed oral hygiene in cases where implants are placed deeper and the ability to resolve mucositis and effectively prevent peri‐implantitis in such situations.

Objective: To compare a four-and six-implant maxillary overdenture after an observation period of 5 years.Material and methods: Fifty subjects with functional problems concerning their maxillary denture, who had ample bone volume in the anterior region to place four or six implants, were included and randomly assigned to either group. Implant and overdenture survival, clinical performance, marginal bone loss and patient satisfaction were assessed.Results: Forty-six patients completed the 5-year follow-up. One implant failed in the six implants group (99.2% survival) and none in the four implants group (100% survival). No overdentures had to be replaced during the observation period and the number of complications was limited. Clinical function was good, with no difference in clinical parameters between the groups. Mean marginal bone resorption was 0.50 +/- 0.37 and 0.52 +/- 0.43 mmin the four and six implant group respectively.Conclusion: In patients with functional complaints of their maxillary denture, bar-supported overdentures on four implants in the anterior maxillary region were not inferior to overdentures supported by six implants after 5 years of function. Implant survival and patient satisfaction were high, clinical parameters favourable, bone loss and complications to the denture were minor in both groups (Clinical trial registration number: NTR2969).

Bone fragility and skeletal irregularities are the characteristic features of osteogenesis imperfecta (OI). Many patients with OI have weakened maxillary and mandibular bone, leading to poor oral hygiene and subsequent loss of teeth. Improvements in implant therapy have allowed for OI patients to achieve dental restoration. However, there is limited available literature on implant therapy for patients with OI. The greatest challenge in the restoration process for OI patients in an outpatient setting is ensuring primary stability and osseointegration. Improvements in synthetic grafts improve successful implant placement and prevent predisposing patients to unnecessary procedures. This report details the successful restoration process of an OI type I patient’s maxillary arch in addition to a review of the currently available literature.

This article analyses published prior article regarding the questions: is the study setup correct (true) and if comparable cases are evaluated for the compared methods. Futhermore the content, the pictures, the tables, the graphs and the pictures legends of the article and statistics are analysed for truth, relevance and applicability. We investigate furthermore if this article addresses all relevant questions regarding bias, the study groups, the evaluation of the outcomes and the evaluation of patient parameters such as burden of the treatment. As a result of the analysis, we state that the analysed article is misleading and it does not provide valuable information regarding decision making for other healthcare professionals in the dental implant field.

Treatment of complex perioprosthetic cases is one of the clinical challenges of everyday practice. Only a complete and thorough diagnostic setup may allow the clinician to formulate a realistic prognosis to select the abutments to support prosthetic rehabilitation. Clinical, radiographic, or laboratory parameters used separately are useless to correctly assign a reliable prognosis to single teeth except in the case of a clearly hopeless tooth. Therefore, it is crucial to gather the greatest quantity of data to determine the role that every single element can play in the prosthetic rehabilitation of the case. The following report deals with the management of a multidisciplinary periodontally compromised case in which a treatment strategy and chronology were designed to reach clinical predictability while reducing the duration of the therapy.

The scope of the study was to evidence the methods recommended for avoiding, managing and implementing an efficient treatment capable of reducing the biological complications accompanying implant therapies. Materials and method. The study evaluates the patients with prosthesis charged implants - or during their osseointegration period - inserted in the Clinic of The Emergency Military Hospital of Sibiu, over a 5 year period (2009-2014). Retrospective investigation was based on the evaluation of the treatment files and on the imagistic and clinical analyses of the 125 patients to whom 385 implants had been inserted. Results and discussion. The study demonstrates that, when implants are the support of an overdenture, surrounded by either limited keratinized gingiva or mobile tissues, the presence of the bacterial plaque is considerable, the peri-implant pocket exceeds 5 mm, and sensitivity and bleeding are produced on contact with the probe. In susceptible patients, or in those with pathological periodontal antecedents, the re-infection potential has been always higher. The clinical study confirms that, invariably, peri-implantitis is associated with the existence of the bacterial plaque and also with the presence of a peri-implant pocket exceeding 4 mm (8.9%), with partial exposure of the covering screw (4.5%) and fixed restaurations without self-cleaning spaces (2%). Conclusions. Out of the post-surgery biological complications, peri-implantitis is the most frequent one, causing a – sometimes total – loss of the alveolar bone around the osseointegrated implant.

Objective To assess the impact of platelet‐rich fibrin (PRF) on implant dentistry. The primary focused question was as follows: What are the clinical, histological, and radiographic outcomes of PRF administration for bone regeneration and implant therapy? Method A systematic literature search comprised three databases: MEDLINE, EMBASE, and Cochrane followed by a hand search of relevant scientific journals. Human studies using PRF for bone regeneration and implant therapy were considered and articles published up to December 31, 2017 were included. Eligible studies were selected based on the inclusion criteria. Randomized controlled trials (RCT) and controlled clinical trials (CCT) were included. Results In total, 5,963 titles were identified with the search terms and by hand search. A total of 12 randomized controlled trials (RCT) met the inclusion criteria and were chosen for data extraction. Included studies focused on alveolar ridge preservation after tooth extraction, osseointegration process, soft tissue management, bone augmentation, bone regeneration after sinus floor elevation and surgical peri‐implantitis treatment. Overall, the risk of bias was moderate or unclear. Nine studies showed superior outcomes for PRF for any of the evaluated variables, such as ridge dimension, bone regeneration, osseointegration process, soft tissue healing. Three studies failed to show any beneficial effects of PRF. No meta‐analysis could be performed due to the heterogeneity of study designs. Conclusions There is moderate evidence supporting the clinical benefit of PRF on ridge preservation and in the early phase of osseointegration. It remains unclear whether PRF can reduce pain and improve soft tissue healing. More research support is necessary to comment on the role of PRF to improve other implant therapy outcomes.

Implantology revolution the treatment of the edentulous patients. In 2002 according to the McGill consensus statement, an implant therapy with two implants in the interforaminal area should be the first choice of treatment for the edentulous mandible. Unfortunately this treatment is outside the financial scope of many edentulous patients or for anatomic reasons. Few authors used a single implant to retained mandibular overdenture. This concept was for the first time describe by Coridoli in1997. Then, few studies have been lead to evaluate what kind of attachments could be used and the biomechanical effect of single implant overdenture. This study assess surgicaly and prostheticaly this new treatment and compared it to two implant’s retained overdenture., L'implantologie a révolutionné le traitement des patients édentés complet. En 2002, le consensus de Mc Gill établit que la prothèse complète stabilisée par deux implants para symphysaires est la thérapeutique de première intention a proposé aux patients édentés à la mandibule. Cependant cette thérapeutique reste parfois difficile d’accès pour des raisons financières ou anatomiques. Plusieurs auteurs proposent l'utilisation d'un seul implant comme moyen de stabilisation d'une prothèse amovible complète. Ce concept a vu le jour en 1997 avec Cordioli, qui présentait des résultats satisfaisants sur 5 ans. Depuis d'autres études ont été menées à ce sujet et visent à approfondir nos connaissances sur le comportement des attachements et des implants dans cette configuration. Cette étude visera a évalué ce concept, tant sur le plan chirurgical que prothétique et de le comparer avec la prothèse complète stabilisée par deux implants.

Aim: To comparatively evaluate the morbidity following maxillary sinus floor elevation according to either transcrestal (tSFE) or lateral (lSFE) approach with concomitant implant placement. Materials & Methods: Patients with ≥1 edentulous maxillary posterior site with residual bone height (RBH) of 3–6mm were enrolled. tSFE was performed in association with a xenograft and a collagen matrix. For lSFE, the sinus was grafted with the xenograft, and the antrostomy was covered with a membrane. Implants were inserted concomitantly. The postoperative course was assessed through questionnaires. Pain level (VASpain) was recorded using a 100-mm visual analogue scale. Results: Twenty-nine and 28 patients were included in tSFE and lSFE group, respectively. On the day of surgery, VASpain was significantly higher for tSFE compared to lSFE, and similar from day 1 to 14. tSFE was characterized by significantly lower incidence of swelling, bruising and nasal discharge/bleeding. Significantly less severe limitation in swallowing, continuing daily activities, eating, speaking, opening the mouth and going to school/work was found for tSFE only at specific postsurgery intervals. Conclusions: lSFE was associated with lower pain on the day of surgery, and tSFE revealed lower postoperative morbidity as well as more tolerable postoperative course.

Objetivos: Avaliar a influência da história de periodontite nos resultados do tratamento com implantes. Materiais e Métodos: Realizou-se uma pesquisa eletrónica na PubMed. Incluíram-se apenas revisões sistemáticas e a meta-análises, publicadas nos últimos 5 anos, em língua inglesa, portuguesa ou francesa. A pesquisa resultou num total de 10 artigos. Resultados: Apesar das elevadas taxas de sobrevivência reportadas, a colocação de implantes em pacientes periodontalmente comprometidos está associada a uma maior ocorrência de complicações biológicas, com uma prevalência mais elevada de periimplantite, com um maior e mais elevado risco de perda óssea peri-implantar, e com taxas de sucesso inferiores, comparativamente a pacientes periodontalmente saudáveis. Este efeito negativo torna-se ainda mais evidente em pacientes com periodontite agressiva, com periodontite severa ou após longos períodos de follow-up. Conclusões: Mais estudos são necessários para confirmar e clarificar os resultados encontrados. Objectives: To evaluate the influence of the history of periodontitis on the results of treatment with implants. Material and Methods : An electronic survey was conducted at PubMed. Only systematic reviews and meta-analysis, published in the last 5 years, in English, Portuguese or French have been included. The search resulted in a total of 10 articles. Results : Despite the high survival rates reported, the placement of implants in periodontally compromised patients is associated with a higher occurrence of biological complications, with a higher prevalence of peri-implantitis, a higher and larger risk of peri-implant bone loss, and lower success rates compared to periodontally healthy patients. This negative effect becomes even more evident in patients with aggressive periodontitis, with severe periodontitis or after long periods of follow-up. Conclusions : More studies are needed to confirm and clarify the results found.

Aim To compare the effectiveness of two-ridge preservation treatments. Materials and Methods 40 subjects with extraction sockets exhibiting substantial buccal dehiscences were enrolled and randomized across 10 standardized centers. Treatments were demineralized allograft plus reconstituted and cross-linked collagen membrane (DFDBA+RECXC) or deproteinized bovine bone mineral with collagen plus native, bilayer collagen membrane (DBBMC+NBCM). Socket dimensions were recorded at baseline and 6-months. Wound closure and soft tissue inflammation were followed post-operatively, and biopsies were retrieved for histomorphometric analysis at 6-months. Results Primary endpoint: at 6-months extraction socket horizontal measures were significantly greater for DBBMC+NBCM (average 1.76 mm greater, p= 0.0256). Secondary and Exploratory endpoints: (1) lingual and buccal vertical bone changes were not significantly different between the two treatment modalities, (2) histomorphometric % new bone and % new bone+graft were not significantly different, but significantly more graft remnants remained for DBBMC; (3) at 1-month incision line gaps were significantly greater and more incision lines remained open for DFDBA+RECXC; (4) higher inflammation at 1-week tended to correlate with lower ridge preservation results; and (5) deeper socket morphologies with thinner bony walls correlated with better ridge preservation. 37 of 40 sites had sufficient ridge dimension for implant placement at 6-months; the remainder were DFDBA+RECXC sites. Conclusion DBBMC+NBCM provided better soft tissue healing and ridge preservation for implant placement. Deeper extraction sockets with higher and more intact bony walls responded more favorably to ridge preservation therapy. Further investigation of implant integration and long-term survival is warranted. clinicaltrials. gov identifier NCT02330523. This article is protected by copyright. All rights reserved.

Background Acceptable short-term survival rates (>90 %) of mini-implants (diameter

Riassunto Obiettivi Il presente articolo studia, attraverso l’analisi della letteratura, gli effetti del diabete sull’osteointegrazione implantare e sulla guarigione dei tessuti molli. Materiali e metodi Negli studi sperimentali si evince che nella patologia diabetica e presente un ridotto contatto fra osso e impianto. Rispetto alla popolazione non affetta da diabete si assiste a una percentuale maggiore di fallimento implantare. La maggior parte di questi fallimenti accade durante il primo anno di carico, attribuendo la causa a problematiche microvascolari. Risultati Sebbene ci sia un alto rischio di fallimento nei pazienti diabetici, studi sperimentali hanno dimostrato che un livello di glicemia controllato incrementa il grado di osteointegrazione implantare. Conclusioni L’incremento della patologia diabetica pone numerosi problemi alla chirurgia implantare, anche se non rappresenta una controindicazione. Le complicanze del diabete possono inficiare la guarigione dei tessuti molli: e necessario effettuare considerazioni preliminari in caso di soggetti diabetici. Un controllo della glicemia e di altri fattori (per esempio emoglobina glicata) puo incrementare la percentuale di sopravvivenza implantare.

Objective Evaluation of differences in the clinical performance and crestal bone levels between implants restored with single crowns with platform-matched or platform-switched abutments after 3 years. Material and Methods The study enrolled adult patients missing two or more adjacent teeth in the posterior mandible with natural teeth mesial to the implant site. Randomization followed open-flap implant insertion and the corresponding matching or switching healing abutments placed at surgery. Conventional loading was made with cemented crowns. Clinical follow-up took place annually after loading up to 3 years. Bone level changes were measured in standardized radiographs as the variation in crestal bone from one evaluation to the next. Results Sixty-three patients with a total of 135 implants (66 platform matching, 69 platform switching) were analysed. From surgery to 36 months, mean bone loss was 0.28 ± 0.56 mm for the platform-switching group and 0.68 ± 0.64 mm for the platform-matching group. A statistically significant difference was found between groups (p = 0.002) with an estimate of 0.39 mm (0.15–0.64, 95% CI) in favour of platform switching. Conclusions After 3 years, platform-switching restorations showed a significant effect in the preservation of marginal bone levels compared to platform-matching restorations.

1999年4月より3年間にわたって大学院卒業者とのプロジェクトを設立し,「プラーク関連疾患の解析」のテーマの下に,(1)プラークの解析,(2)齲蝕の解析,(3)歯周炎の解析,(4)根尖性歯周炎の解析,(5)歯科インプラント治療の解析という五種類の解析に取り組んだ.それぞれには多様な研究課題あるいは研究分野があるが,今回はとくに基礎的解析を中心的目標とした.「プラーク関連疾患の解析」の基礎の中の基礎であるプラークそのものについては,歯肉縁上プラークおよび歯肉縁下プラークの形成過程の形態的追跡をテーマとした.このプラーク形成過程はとくにヒトでは殆んど知られていない.これはヒト天然歯面上のプラークをintactな状態でしかも大量に採取することが不可能なことによる.そこで本研究では,天然歯硬組織成分に近縁なcarbonate apatiteを応用し,この薄片をヒト天然歯面に貼り付ける方法(歯肉縁上プラーク)と,3mm以上の歯周ポケットに挿入する方法(歯肉縁下プラーク)の二法でこの問題点を解決した.その結果,歯肉縁上プラークはペリクル形成期,細菌付着期,初期コロニー形成期,前オーガナイズ期,細菌叢変換期,後オーガナイズ期の六期で成熟プラークが完成し,これに対して歯肉縁下プラークはペリクル形成期,細菌付着期,初期コロニー形成期,前オーガナイズ期,後オーガナイズ期の五期にわたることが明らかになった.両プラークは,ペリクル形成,細菌付着,初期コロニー形成,オーガナイズという形成期は一致していたが,それぞれの形成時期が歯肉縁下プラークでは著しく緩慢に経過し,互いにオーバーラップを見せ,明確な菌叢変換期がないという三つの点で歯肉縁上プラークとは大きく違っていた.またペリクルは,歯肉縁上の場合,唾液成分が関連したのに対し,歯肉縁下のそれは主として歯肉滲出液であり,ペリクル付着細菌については,歯肉縁上では主としてグラム陽性球菌,一部にグラム陽性桿菌であったのに対し,歯肉縁下ではグラム陽性桿菌のみである点でも著しい違いがみられた.さらに,歯肉縁上では菌叢変換前まではこのグラム陽性球菌を中心としてプラークが形成され,それ以降はグラム陽性桿菌が中心であったのに対し,歯肉縁下では終始initial colonizerのグラム陽性桿菌が主要な細菌の位置を占める点でも異なっていた.なお,両プラーク形成期のinitial colonizerである桿菌が,オーガナイズ期でsecondary colonizerのグラム陰性線状菌と二層性の定常的細菌構築を形成したことは共通していた.歯肉縁下プラークでは,この二層性の定常的構築が,いわゆるtooth-associated plaqueの主要細菌であり,その表面にグラム陰性球菌群や桿菌群が増殖し,いわゆるenithelium-associated plaqueを形成すると見なし得た.そして,tooth-associated plaque中の細菌叢はとくに二層性構築形成細菌の菌叢が変化しないのに対して,epithelium-associated plaque中の細菌は常に量的・質的変動を反復し,この量的・質的変動が歯肉炎の発症や経過に関連していることが示唆された.このような歯肉縁下プラークと歯周炎の発症や経過に関しては,ヒトにおいても実験的歯肉炎発症実験である程度明らかにされている.しかし,プラーク細菌の形成過程との関係,およびその際の細菌構築との関係といった分野の基礎的データは全く得られていない.そこでこの点を明らかにするために,我々はやはりCAPをヒト歯周ポケットに挿入し,細菌の動向を歯肉炎発症と関連づけて検索した.その結果,歯肉炎は歯肉縁下プラーク形成過程の確立期に,被験者の約50%に発症し,その際のプラークは, tooth-associated plaqueにおいて細菌増殖期に一致するか,あるいはtooth-associated plaque表層に著しい貪食細胞が浸潤し,細菌が殆んど見られないかの二つの状態を示した.この所見は,ある種のepithelium-associated plaque細菌が直接的に歯肉に炎症反応を惹起させる作用のあること,そしてその一過程として浸潤した貪食細胞が同部の細菌を捕食することによって防御的に作用していること,さらにこれらの貪食細胞の自己融解が二次的に組織破壊性に作用することの三点が示唆された.齲蝕の継発症である根尖性歯周炎については二つの検索を行った.その一つは,Actinomycesを中心とした口腔内細菌の病巣への侵襲の有無と程度,およびこれら細菌の生体組織に与える影響についてであり,もう一つは根管内細菌と根尖性歯周炎との関係についてである.病巣内の細菌の検出には培養法等種々あるが,組織レベルでは免疫組織化学的手法が最も妥当である.しかし,病巣の細菌成分が可溶状態である場合にはこれらの方法では検出は不可能に近い.この観点に立てば,これまでの根尖性歯周炎病巣内への細菌侵襲に関するデータはかなり正確性に欠くものと考えられる.そこで今回,この点を解決するために,免疫組織化学的手法だけでなく,病巣からの溶出液のimmunoblot解析法をも検索に加えた.その結果,免疫組織化学的手法では, This review describes the results both basic and clinical studies on dental plaque and its associated diseases, such as supra-and sub-gingival plaque formation, initiation of dental caries, periodontal diseases and apical periodontitis, and a series of basic examinations of implant therapy which were carried out in a joint study with several post-graduated doctors. Morphological analysis of dental plaque formation, the starting point of a chain of major infections in the oral cavity, was performed with deposits on a synthesized carbonate apatite thin layer applied both on human tooth surfaces (supragingival plaque), and in human periodontal pockets (subgingival plaque). The morphological studies clarified that the sequential phase of supragingival plaque formation over a 3-week period can be subdivided into 6 phases ; pellicle formation phase, microbial adherence phase, initial colonization phase, pre-organization phase, microflora alteration phase and post-organization phase. Subgingival plaque formation could be subdivided into 5 phases ; pellicle formation phase, microbial adherence phase, initial colonization phase, pre-microbial organization phase and past-microbial organization phase. From the results, it was clear that the sequential phase of dental plaque formation is different between supragingival and subgingival plaque. Immuno-electron microscopy using colloidal gold conjugated antibodies to the human parotid salivary proteins or to human plasma proteins revealed that the main components of supragingival pellicle and subgingival pellicle are salivary proteins and plasma proteins which derived from gingival exudates. SEM and TEM showed that the predominant microbiota which adhere to such pellicle in the supragingival plaque formation were Gram-positive coccoid types and Gram-positive bacillary types, while examination of the microbiota in subgingival pellicle revealed only one genus showing Gram-positive bacillary type. After the adherence to the pellicle, they proliferated on the pellicle as the initial colonizers. These initial colonizers, however, exhibited a difference in a velocity of proliferation. It was observed that the coccoid types proliferated faster than the bacillary types. Thus, the predominant microbiota among the initial colonizers until the microflora alteration phase of supragingival plaque formation were the coccoid types. However, genera of initial colonizers after both the microflora alteration phase of supragingival plaque formation and in all sequential phases of subgingival plaque formation were Gram-positive bacillary types and furthermore, minute investigation of these bacillary cells demonstrated them to be the same genus of microbiota both in supragingival and in subgingival plaque. The formation of stable structure by combination of certain genera of microbiota was a common phenomenon between supragingival and subgingival plaque. The genera of the stable structure composing cells were the coccoid initial and filamentous secondary colonizers in the pre-organization phase of supragingival plaque formation. In the formation of subgingival plaque, such initial and secondary colonizers proliferated on the CAP surface, and other genera of microbiota multiprecated on the superficial layer of the stable structures. In subgingival plaque, therefore, the plaque on the CAP formed by initial and secondary colonizers was considered to correspond to the so-called tooth-associated plaque, and the plaque on the superficial layer was thought to be epithelium-associated plaque. The microbiota in epithelium-associated plaque consisted of Gram-negative cocci, coccobacilli and spirochetes, and showed a tendency to repeatedly increase and decrease in number. Quantitative and qualitative changes of microbiota in epithelium-associated plaque were considered to be closely related with initiation and progression of periodontal diseases. In spite of a number of studies concerning periodontal disease, the relations

Objective The purpose of this ongoing randomized study was to assess differences in bone level changes and success rates using implants supporting single crowns in the posterior mandible either with platform matched or platform switched abutments. Material and Methods Patients aged 18 and above, missing at least two teeth in the posterior mandible and with a natural tooth mesial to the most proximal implant site were enrolled. Randomization followed implant placement. Definitive restorations were placed after a minimum transgingival healing period of 8 weeks. Changes in crestal bone level from surgery and loading (baseline) to 12-month post-loading were radiographically measured. Implant survival and success were determined. Results Sixty-eight patients received 74 implants in the platform switching group and 72 in the other one. The difference of mean marginal bone level change from surgery to 12 months was significant between groups (p