Preservation of crestal bone by implant design. A comparative study in minipigs.

OBJECTIVES: To compare crestal bone modeling at three bone level design implants; Astra Tech Osseospeed(™) Implant (AOI), Straumann(®) Bone Level Implant (SBLI) and NobelReplace(™) Tapered Groovy Implant (NBTI). MATERIALS AND METHODS: In 12 minipigs one implant of each design was placed on each side of the mandible with submerged healing. The implant platform was placed at the level of the crest (Group 0), and 1 mm above the crest (Group + 1 mm). In addition, one Straumann(®) Tissue Level Implant STLI was placed as a control on each side of the mandible. At 4 weeks, six animals were sacrificed. In the remaining six animals healing abutments were connected until 12 weeks. Clinical, radiographic, and histologic analyses were made. ANOVA and Mann-Whitney U-tests were used to evaluate differences in bone levels between implant designs. RESULTS: At 4 weeks there was no statistically significant difference in bone changes between implant designs. At 12 weeks implants in Group + 1 mm had minimal bone changes with no differences between implant designs. In Group 0, the AOI and SBLI preserved more crestal bone than NBTI (P < 0.01). Mean distance from the implant platform to the buccal bone was -0.1 ± 0.2 mm for AOI, -0.3 ± 0.3 mm for SBLI, and -1.0 ± 0.3 mm for NBTI. Mean radiographic bone levels from the implant platform were -0.1 ± 0.4 mm for AOI, 0.0 ± 0.3 mm for SBLI and -0.9 ± 0.8 mm for NBTI. CONCLUSION: Greater bone preservation was observed for the AOI and SBLI compared with the NBTI.

Anti-infective surgical therapy of peri-implantitis. A 12-month prospective clinical study.

AIM: The aim of this prospective cohort study was to evaluate an anti-infective surgical protocol for the treatment of peri-implantitis. MATERIALS AND METHODS: Thirty-six implants in 24 partially dentate patients with moderate to advanced peri-implantitis were treated using an anti-infective surgical protocol incorporating open flap debridement and implant surface decontamination, with adjunctive systemic amoxicillin and metronidazole. Treatment outcomes were assessed at 3, 6 and 12 months. Patient-based statistical analyses using multiple regression analyses were performed. RESULTS: There was 100% survival of treated implants at 12 months. At 3 months, there were statistically significant (P < 0.01) reductions in mean probing depths (PD), Bleeding on Probing (BoP) and suppuration. The greater the mean PD at baseline, the greater the PD reduction at 3 months. At 3 months, there was also a significant mean facial mucosal recession of 1 mm (P < 0.001). All these changes were maintained at 6 and 12 months. At 12 months, all treated implants had a mean PD < 5 mm, while 47% of the implants had complete resolution of inflammation (BoP negative). At 12 months, 92% of implants had stable crestal bone levels or bone gain. There were no significant effects of smoking on any of the treatment outcomes. CONCLUSIONS: For the treatment of peri-implantitis, an anti-infective protocol incorporating surgical access, implant surface decontamination and systemic antimicrobials followed by a strict postoperative protocol was effective at 3 months with the results maintained for up to 12 months after treatment.

University postgraduate training in implant dentistry for the general dental practitioner.

AIMS OF THIS PAPER: This paper aims to: (1) Describe the educational requirements of general practitioners who want to safely and effectively introduce implant dentistry procedures to their practice. (2) Define the necessary competencies and level of complexity that would need to be attained in a postgraduate implant dentistry programme for general dental practitioners. (3) Discuss the programme structures which universities can utilize in order to provide quality education in implant dentistry for general practitioners. (4) Provide guidelines for the resources, content, course format and instructional methods which could be well suited to the educational requirements of such programmes. The authors intend to produce a headline reference guide to outline the necessary educational structures for postgraduate pathways aimed at facilitating the continuous professional development of general practitioners within implant dentistry. This paper does not address issues concerning specialist training or higher research degrees.

Systemic antibiotics in periodontal therapy.

Periodontitis is a biofilm infection with a mixed microbial aetiology. Periodontitis is generally treated by non-surgical mechanical debridement and regular periodontal maintenance care. Periodontal surgery may be indicated for some patients to improve access to the root surface for mechanical debridement. A range of systemic antibiotics for treatment of periodontitis has been documented, with some studies showing superior clinical outcomes following adjunctive antibiotics while others do not. This has resulted in controversy as to the role of systemic antibiotics in the treatment of periodontal diseases. Recent systematic reviews have provided an evidence-based assessment of the possible benefits of adjunctive antibiotics in periodontal therapy. This review aims to provide an update on clinical issues of when and how to prescribe systemic antibiotics in periodontal therapy.

Diagnosis and management of peri-implant diseases.

Peri-implant diseases are inflammatory lesions which may affect the peri-implant mucosa only (peri-implant mucositis) or also result in loss of supporting bone (peri-implantitis). Peri-implantitis may lead to loss of the implant. Diagnosis of peri-implant disease requires the use of conventional probing to identify the presence of bleeding on probing, and suppuration, both signs of clinical inflammation. Radiographs are required to detect loss of supporting bone. Baseline probing measurements and radiographs should be obtained once the restoration of the implant is completed to allow longitudinal monitoring of peri-implant conditions. Two cross-sectional reports from Sweden indicate that the prevalence of peri-implant disease is high. Smokers and patients who have a history of periodontitis are more at risk for peri-implant disease. The main goal of treatment of peri-implant disease is to control the infection and to prevent disease progression. A number of studies have documented the successful treatment of peri-implant mucositis combining mechanical debridement and chemical plaque control. There is evidence supporting antimicrobial treatment regimens in combination with non-surgical or surgical debridement for peri-implantitis treatment. Long-term data to support these treatment protocols is limited. Whilst it is possible to treat peri-implantitis, prevention is the goal of supportive therapy.

Disease progression: identification of high-risk groups and individuals for periodontitis.

AIMS: While the role of bacteria in the initiation of periodontitis is primary, a range of host-related factors influence the onset, clinical presentation and rate of progression of disease. The objectives of this review are (1) to present evidence for individual predictive factors associated with a patient's susceptibility to progression of periodontitis and (2) to describe the use of prognostic models aimed at identifying high-risk groups and individuals in a clinical setting. METHODS: Relevant publications in the English language were identified after Medline and PubMed database searches. Because of a paucity of longitudinal studies investigating factors including clinical, demographic, environmental, behavioural, psychosocial, genetic, systemic and microbiologic parameters to identify individuals at risk for disease progression, some association studies were also included in this review. FINDINGS AND CONCLUSIONS: Cigarette smoking is a strong predictor of progressive periodontitis, the effect of which is dose related. High levels of specific bacteria have been predictive of progressive periodontitis in some studies but not all. Diabetics with poor glycaemic control have an increased risk for progression of periodontitis. The evidence for the effect of a number of putative factors including interleukin-1 genotype, osteoporosis and psychosocial factors is inconclusive and requires further investigation in prospective longitudinal studies. Specific and sensitive diagnostic tests for the identification of individuals susceptible to disease progression are not yet a reality. While factors assessed independently may not be valuable in predicting risk of future attachment loss, the combination of factors in a multifactorial model may be useful in identifying individuals at risk for disease progression. A number of multifactorial models for risk assessment, at a subject level have been developed but require validation in prospective longitudinal studies.

Impact of sample storage on detection of periodontal bacteria.

BACKGROUND/AIMS: Information on the impact of sample storage prior to analysis by DNA methods is limited. The aim of this study was to investigate the effect of subgingival sample storage on bacterial detection and enumeration. MATERIAL AND METHODS: Subgingival plaque samples were studied by a) checkerboard DNA-DNA hybridization by immediate processing, b) storage at + 4 degrees C for 6 weeks, c) storage at - 20 degrees C for 6 months or d) storage at - 20 degrees C for 12 months. RESULTS: No differences in total DNA were found between protocol 1 and 2, or between protocol 3 and 4. Protocol 1 yielded 2.4 times more total bacterial DNA than did protocol 3 (P < 0.001). Actinobacillus actinomycetemcomitans and Campylobacter gracilis were detected in 21.1% of the immediately processed samples but only in 6.6% of the samples after 12 months of storage. Similar changes were noticed for Treponema denticola, which was detected in 22.3% and 9.2%, respectively. Streptococci spp., Fusobacterium nucleatum and Tannerella forsythia did not seem to be affected by storage. In contrast, the level of Campylobacter rectus detection frequency changed from 2.6% if processed immediately to 15.8% if samples were stored for 12 months. CONCLUSIONS: In longitudinal clinical studies including microbiological samples and processed with DNA-DNA hybridization methods, samples should be stored for the same period of time before processing to avoid loss of microbiological information.

Effects of post-surgical cleansing protocols on early plaque control in periodontal and/or periimplant wound healing.

OBJECTIVE: The aim of this RCT was to evaluate early wound healing following specific post-surgical care protocols. MATERIAL AND METHODS: Following periodontal flap surgery, 60 patients were randomly assigned to follow one of two post-surgical protocols. Subjects smoking >20 cigarettes per day were excluded. Patients following the control protocol rinsed twice daily for 1 min with 0.1% of chlorhexidine (CHX) for 4 weeks. In addition to CHX rinsing, patients assigned to the test protocol applied CHX locally using a special very soft surgical toothbrush (Chirugia) from days 3 to 14, and a soft toothbrush (Ultrasuave) from days 14 to 28, twice daily. Baseline measurements included gingival crevicular fluid (GCF) flow rate, probing depth, probing attachment level, presence of bleeding on probing and full-mouth plaque score. Measurements were repeated at 1, 2 and 4 weeks after surgery. RESULTS: Both post-surgical protocols resulted in successful wound healing and optimal wound closure at 4 weeks. There were no statistical differences in the GCF flow rate between test and control protocols. There was a lower incidence of recession of > or =2 mm following the test protocol. CONCLUSION: The use of specific post-surgical cleansing protocols including the introduction of mechanical cleansing at day 3, using local application of CHX in addition to daily rinsing with CHX may be recommended.

Does excessive occlusal load affect osseointegration? An experimental study in the dog.

AIM: The purpose of this study was to evaluate the effect of excessive occlusal load following placement of titanium implants in the presence of healthy peri-implant mucosal tissues. MATERIALS AND METHODS: Mandibular bilateral recipient sites in six Labrador dogs were established by extracting premolars and molars. After 3 months, two TPS (titanium plasma sprayed) implants and two SLA (sandblasted, large grit, acid etched) implants were placed on each side of the mandible in each dog. Three implants were lost in the initial healing phase, leaving 45 implants for evaluation. Following 6 months of healing, gold crowns were placed on implants on the test side of the mandible. The crowns were in supra-occlusal contact with the opposing teeth in order to create excessive occlusal load. Implants on the control side were not loaded. Plaque control was performed throughout the experimental period. Clinical measurements and standardised radiographs were obtained at baseline and 1, 3 and 8 months after loading. At 8 months, the dogs were killed and histologic analyses were performed. RESULTS: At 8 months, all implants were osseointegrated. The mean probing depth was 2.5+/-0.3 and 2.6+/-0.3 mm at unloaded and loaded implants, respectively. Radiographically, the mean distance from the implant shoulder to the marginal bone level was 3.6+/-0.4 mm in the control group and 3.7+/-0.2 mm in the test group. Control and test groups were compared using paired non-parametric analyses. There were no statistically significant changes for any of the parameters from baseline to 8 months in the loaded and unloaded implants. Histologic evaluation showed a mean mineralised bone-to-implant contact of 73% in the control implants and 74% in the test implants, with no statistically significant difference between test and control implants. CONCLUSION: In the presence of peri-implant mucosal health, a period of 8 months of excessive occlusal load on titanium implants did not result in loss of osseointegration or marginal bone loss when compared with non-loaded implants.

A systematic review of the effect of surgical debridement vs non-surgical debridement for the treatment of chronic periodontitis.

OBJECTIVE: To systematically review the evidence of effectiveness of surgical vs. non-surgical therapy for the treatment of chronic periodontal disease. METHODS: A search was conducted for randomized controlled trials of at least 12 months duration comparing surgical with non-surgical treatment of chronic periodontal disease. Data sources included the National Library of Medicine computerised bibliographic database MEDLINE, and the Cochrane Oral Health Group (COHG) Specialist Trials Register. Screening, data abstraction and quality assessment were conducted independently by multiple reviewers (L.H., F.H., L.T.). The primary outcome measures evaluated were gain in clinical attachment level (CAL) and reduction in probing pocket depth (PPD). RESULTS: The search provided 589 abstracts of which six randomized controlled trials were included. Meta-analysis evaluation of these studies indicated that 12 months following treatment, surgical therapy resulted in 0.6 mm more PPD reduction (WMD 0.58 mm; 95% CI 0.38, 0.79) and 0.2 mm more CAL gain (WMD 0.19 mm; 95% CI 0.04, 0.35) than non-surgical therapy in deep pockets (>6 mm). In 4-6 mm pockets scaling and root planing resulted in 0.4 mm more attachment gain (WMD -0.37 mm; 95% CI -0.49, -0.26) and 0.4 mm less probing depth reduction (WMD 0.35 mm; 95% CI 0.23, 0.47) than surgical therapy. In shallow pockets (1-3 mm) non-surgical therapy resulted in 0.5 mm less attachment loss (WMD -0.51 mm; 95% CI -0.74, -0.29) than surgical therapy. CONCLUSIONS: Both scaling and root planing alone and scaling and root planing combined with flap procedure are effective methods for the treatment of chronic periodontitis in terms of attachment level gain and reduction in gingival inflammation. In the treatment of deep pockets open flap debridement results in greater PPD reduction and clinical attachment gain.

Evaluation following functional loading of titanium fixtures placed in ridges augmented by deproteinized bone mineral. A human case study.

The aim of this investigation was to clinically evaluate the periimplant tissues of titanium fixtures, placed in regions augmented using deproteinized bone mineral, after initial functional loading. The original material included 18 individuals (mean age 71+/-9 years) treated using a graft material, Bio-Oss (6 Patients), or Bio-Oss+autogenous bone mixture (12 patients) for alveolar ridge augmentation. 6 titanium fixtures were placed at the time of ridge augmentation. 46 fixtures were placed at a second surgical stage, median 9.5 months after augmentation. Augmentation included crest width (26 fixtures), crest height and width (12 fixtures) and sinus floor lift (14 fixtures) procedures. In addition, 16 fixtures were placed in regions of adequate bone volume. Reconstructions were placed and patients were recalled on a yearly basis. After 4-6.5 years of functional loading, the reconstructions were removed and assessments of fixture stability and periimplant mucosal conditions were made. At this time, 3 patients (13 fixtures) were lost to follow-up (1 deceased, 1 declined to participate, and 1 too ill to attend). In the remaining 15 patients, 7 fixtures were lost due to osseo-disintegration, 2 in one patient in the mandible, and 5 in a second patient in the maxilla. Both individuals were smokers. The remaining 32 fixtures were clinically stable. Periimplant mucosa was healthy with a mean modified sulcular bleeding index of 0.1+/-0.2 and a mean probing depth of 1.5+/-1.1 mm. Radiographic evaluation showed alveolar bone levels at or above the level of the first fixture thread. There were no perifixtural radiolucencies. The survival rate, which coincided with success rate, for fixtures placed in conjunction with ridge augmentation using deproteinized bone mineral was 100% for non-smokers and 43% for smokers after 4-6.5 years of functional loading. No fixture loss occurred in non-augmented areas.

A bridge between the RNA and protein worlds? Accelerating delivery of chemical reactivity to RNA and DNA by a specific short peptide (AAKK)(4).

BACKGROUND: RNA can catalyze diverse chemical reactions, leading to the hypothesis that an RNA world existed early in evolution. Today, however, catalysis by naturally occurring RNAs is rare and most chemical transformations within cells require proteins. This has led to interest in the design of small peptides capable of catalyzing chemical transformations. RESULTS: We demonstrate that a short lysine-rich peptide (AAKK)(4) can deliver a nucleophile to DNA or RNA and amplify the rate of chemical modification by up to 3400-fold. We also tested similar peptides that contain ornithine or arginine in place of lysine, peptides with altered stereochemistry or orientation, and peptides containing eight lysines but with different spacing. Surprisingly, these similar peptides function much less well, suggesting that specific combinations of amino acids, charge distribution, and stereochemistry are necessary for the rate enhancement by (AAKK)(4). CONCLUSIONS: By appending other reactive groups to (AAKK)(4) it should be possible to greatly expand the potential for small peptides to directly catalyze modification of DNA or RNA or to act as cofactors to promote ribozyme catalysis.

Town and gown in America: some historical and institutional issues of the engaged university.

The engaged university is a descriptive term for linking the different perspectives of university/community partnerships in higher education in the United States. While interest in this idea comes from recent events and processes, there is an historical background for university/community relations that offers important suggestions on the issue related to institutionalizing this concept. The history includes the original religious founding of US institutions, the establishment of the land-grant system of colleges, and the expansion of the mass education system in US universities. The development of community-based research disciplines, dating from the time of the settlement house movement in America, provides support for university/community collaboration. While some faculty and administrators support this idea, others are more critical and do not see it supporting the strategic interests of their institutions or disciplines. Comprehensively supporting the engaged university at an institutional level means changing the way the academy operates and including community concerns in research, teaching and administrative decisions. This article explores some of these issues and some possible solutions.

Diagnostic characteristics of clinical and microbiological tests for monitoring periodontal and peri-implant mucosal tissue conditions during supportive periodontal therapy (SPT).

The aim of this study was to evaluate a clinical and a microbiological test for monitoring tissue condition during supportive periodontal therapy (SPT) and to compare their diagnostic characteristics at implant and tooth sites. Twelve female (age: 37-72 years) and 7 male patients (age: 26-83 years) were evaluated in this study on the basis of availability to follow a rigid SPT program. Patients had received a complete periodontal examination at 1 and 5 years after implant placement. This included standardized radiographs obtained at implants and matching control teeth. One implant site and one tooth site per patient were followed during the last 2 years of the SPT program. At each recall visit microbiological samples were analyzed according to DNA/RNA analysis identifying periodontal pathogens (IAI Pado Test 4.5, Institute for Applied Immunology, Zuchwil, Switzerland). Presence or absence of bleeding on probing at these sites was also noted using a standardized probing force of 0.25 N (Audio Probe, ESRO, Thalwil ZH, Switzerland). The percentage number of recall visits with positive bacteriological test results and positive BOP scores were calculated. Disease progression at the sites was defined if the annual increase in probing depth was > or = 0.5 mm/year (2.5 mm in 5 years) or if the annual decrease in CADIA values (Computer Assisted Densitometric Image Analysis) was more than -0.7 per year (-3.5 in 5 years). Changes below these values were considered as negative test results indicating stability of the sites. The diagnostic characteristics (sensitivity, specificity, positive and negative predictive values) of BOP and microbiological tests alone or in combination were then calculated using two-by-two tables. By application of increasing thresholds of BOP frequencies set for definition of positive test outcome (BOP > or = 10% > or = 20% > or = 25% > or = 50% > or = 75% > or = 90% or the combined BOP > or = 75%, but DNA positive > or = 10%, > or = 25% > or = 34% > or = 50% > or = 67% > or = 90%) receiver operator characteristics curves (ROC) were constructed for teeth and implants. The areas under the ROC curves were calculated and compared by means of chi-square tests. The results indicated statistically significant better diagnostic characteristics of both tests at implants compared to teeth. The inclusion of an additional microbiological test significantly enhanced the diagnostic characteristics of BOP alone at teeth as well as at implants.

Enhancing solid phase synthesis by a noncovalent protection strategy-efficient coupling of rhodamine to resin-bound peptide nucleic acids.

Resins for solid-phase synthesis can affect coupling efficiencies by interacting with reactants. We have observed that polyethylene glycol-polystyrene (PEG-PS) solid support absorbs added activated fluorophores, preventing efficient labeling of peptide nucleic acids (PNAs). We now report that addition of an inexpensive unactivated fluorophore blocks the resin and allows efficient labeling. This protection strategy may have general benefits for peptide and combinatorial synthesis.

Clinical and radiographic evaluation, following delivery of fixed reconstructions, at GBR treated titanium fixtures.

Conditions following incorporation of fixed reconstructions, at endosseous titanium implants augmented at local bony dehiscence and fenestration defects using a bioabsorbable Resolut membrane were studied in 7 patients. Fixture stability, radiographic marginal bone levels and peri-implant soft tissue status were evaluated at 21 membrane treated and 17 control fixtures (installed in regions of adequate bone volume), following a 2-year period of functional loading. Prosthetic reconstructions were removed and clinical examination and Periotest values revealed that all fixtures were stable. All peri-implant soft tissues were clinically healthy. The mean probing depths at buccal sites for fixtures with original dehiscence (n = 10) and fenestration (n = 11) defects were 1.6 +/- 0.7 mm and 1.2 +/- 0.4 mm respectively. The control fixture group had a mean buccal probing depth of 1.4 +/- 0.6 mm. At abutment connection radiograph membrane treated fixtures had significantly lower marginal bone levels than control fixtures, indicating that optimal bone regeneration was not achieved at all defects. Mean radiographic bone loss 23-27 months following delivery of fixed reconstructions for original dehiscence and fenestration defect fixtures was 0.7 +/- 0.8 mm and 0.8 +/- 0.6 mm respectively at mesial surfaces, and 0.8 +/- 0.7 mm and 0.6 +/- 0.5 mm at distal surfaces. In the control fixture group a mean loss of 0.7 +/- 0.5 mm at mesial surfaces and 0.5 +/- 0.4 mm at distal surfaces was found. Results showed no significant difference in the rate of bone loss following functional loading between membrane treated and control fixtures.

Root conditioning using EDTA gel as an adjunct to surgical therapy for the treatment of intraosseous periodontal defects.

The aim of this clinical study was to compare the treatment outcome following root surface conditioning using an EDTA gel preparation in conjunction with surgical therapy with that following conventional flap surgery in periodontal intraosseous defects. 36 patients, each of them contributing one intraosseous defect > or =4 mm in depth participated. Defect sites had a probing pocket depth > or =5 mm and bled on probing following hygienic treatment phase. No furcation involvement or endodontic complications were present. In the EDTA group, 18 consecutive patients, defects were treated by root conditioning with EDTA gel for 3 minutes in combination with surgical therapy. In the control group, 18 patients, conventional flap surgery was performed without root conditioning. Chlorhexidine rinsings 0.2% were prescribed following surgery for 2-3 weeks with modified oral hygiene instruction. A strict recall program was implemented including professional prophylaxis and oral hygiene reinforcement every 4-6 weeks until 6-month re-evaluation. Baseline probing pocket depths and defect depths of 7.1+/-1.3 mm and 6.9+/-1.6 mm in the EDTA group and 7.6+/-1.9 mm and 6.6+/-1.7 mm, respectively, in the control group were measured. 6-month clinical results showed a significant probing attachment level gain of 1.8+/-1.5 mm and 1.0+/-1.7 mm in the EDTA and control groups respectively. A probing bone gain of 1.0+/-1.3 mm in the EDTA group was measured with a non-significant gain of 0.4+/-1.2 mm in the control group. Radiographic analysis confirmed these results. There were no statistically significant differences in treatment outcome between the group treated by root conditioning in combination with flap surgery and conventional flap surgery alone.