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For decades, oral implants have been used successfully for the replacement of missing teeth. Nevertheless, peri-implant diseases have become an increasingly important issue in daily practice. In this working group, the prevalence of peri-implant mucositis and peri-implantitis, as well as different general risk factors and their impact on the onset and progression of peri-implant diseases, were discussed based on reviews reflecting the current state of evidence. The influence of smoking on the peri-implant bone-healing process and its association with peri-implantitis has been explored in the current literature, demonstrating that smoking is an important risk indicator for the development of peri-implantitis and implant loss. Compared with non-smokers, smokers have a higher potential for pathological peri-implant bone loss, which is also influenced by poor oral hygiene. Despite the fact that a growing number of genetic polymorphisms have been identified and related to periodontal diseases, there are still no genetic patterns that could act as adjuncts to clinical diagnostics in order to identify patients at higher risk of peri-implant diseases. Long-term medications, such as bisphosphonate therapy (> 3 years), may have an impact on implant loss. A higher incidence of implant failure was reported in patients using selective serotonin reuptake inhibitors in anti-depression therapy. Alcoholism (defined as more than 5 units a day) has been associated with implant loss in retrospective and case–control studies, as well as in animal studies.

STATEMENT OF PROBLEM: Implant-based prosthetic solutions can be time consuming. If implants can be loaded immediately, treatment time can be reduced. PURPOSE: The purpose of this prospective randomized controlled trial was to monitor the survival rate of Ankylos implants, comparing conventional with immediate loading by using abutments with the SynCone concept for screw-retained removable prostheses in the edentulous maxilla. MATERIAL AND METHODS: A total of 90 implants were placed in 15 study participants. The participants were randomly assigned to the immediate or conventional loading treatment group. Radiographic and clinical parameters were recorded at the time of permanent prosthesis installment and at 1- and 2-year follow-up examinations, and participants' satisfaction was measured by using questionnaires before and after prosthesis installation. A linear mixed model was used to measure differences. RESULTS: One implant in the conventional group was lost during abutment placement; hence, 89 implants could be followed for 2 years. Approximately 90% of these implants showed no bone loss or even bone gain at 1 and 2 years follow-up. Mean values for the immediate group were, respectively, 0.09 ±0.35 mm and 0.13 ±0.38 mm and 0.01 ±0.41 mm and -0.06 ±0.32 mm for the conventional method. No significant differences (P=.053) were found in bone level alterations between the groups. For all participants, the mean number of surfaces (4 per implant) with bleeding on probing (BoP) and plaque were 0.76 ±0.81 and 0.16 ±0.42 at 1 year follow-up and 0.44 ±0.66 and 0.02 ±0.15, respectively, at the second-year follow-up. The mean pocket probing depths were 2.05 ±0.54 mm at 1 year and 2.18 ±0.64 mm at 2 years. For both groups, a significant rise in satisfaction and quality of life was observed (P≤.001) at 1 and 2 years compared with pretreatment. CONCLUSIONS: Ankylos implants placed in the edentulous maxilla, immediately or conventionally loaded by a detachable prosthesis, showed favorable bone-level preservation after 2 years of follow-up. No significant differences could be found between the immediate and conventional groups. A significant increase in quality of life was observed for both loading modes. ispartof: JOURNAL OF PROSTHETIC DENTISTRY vol:121 issue:2 pages:258-264 ispartof: location:United States status: published

Objectives The objectives of this study are to identify oral commensal species which can inhibit the growth of the main periodontopathogens, to determine the antimicrobial substances involved in these inhibitory activities and to evaluate the influence of environmental factors on the magnitude of these inhibitions. Methods The spotting technique was used to quantify the capacity of 13 commensal species to inhibit the growth of Aggregatibacter actinomycetemcomitans, Porphyromonas gingivalis and Prevotella intermedia. By altering experimental conditions (distance between spots and size of spots and concentration of commensal and pathogen) as well as environmental factors (inoculation sequence, oxygen and nutrition availability) the influence of these factors was evaluated. Additionally, the mechanism of inhibition was elucidated by performing inhibition experiments in the presence of peroxidase, trypsin and pepsin and by evaluating acid production. Results Streptococcus sanguinis, Streptococcus cristatus, Streptococcus gordonii, Streptococcus parasanguinis, Streptococcus mitis and Streptococcus oralis significantly inhibit the growth of all pathogens. The volume of the spots and concentration of the commensal have a significant positive correlation with the amount of inhibition whereas distance between the spots and concentration of the pathogen reduced the amount of inhibition. Inhibition is only observed when the commensal species are inoculated 24 h before the pathogen and is more pronounced under aerobic conditions. Hydrogen peroxide production by the commensal is the main mechanism of inhibition. Conclusion Bacterial antagonism is species specific and depending on experimental as well as environmental conditions. Blocking hydrogen peroxide production neutralizes the inhibitory effect. Clinical significance Identifying beneficial oral bacteria and understanding how they inhibit pathogens might help to unravel the mechanisms behind dysbiotic oral diseases. In this context, this study points towards an important role for hydrogen peroxide. The latter might lead in the future to novel preventive strategies for oral health based on improving the antimicrobial properties of commensal oral bacteria.

Objectives Fractures of distal bar extensions, supporting a mandibular overdenture, do occur with significant functional and economic consequences for the patient. This study therefore aims to evaluate the effect of different bar cross-sectional shapes and surfaces, bar extension lengths and the placement of a support rib under the distal bar extension on fracture resistance. Materials and methods The 2nd moment area and static strength were calculated for 11 frequently used bar designs using finite element analysis (FEA). For two specific designs (Ackermann round O 1.8 mm and Dolder-Y macro, the former with and without a support rib) additional physical static and fatigue strength tests were included. Results The FEA static strength data corresponded well to the 2nd moment area (a similar ranking when maximum allowed force was considered). The application of a rib support (Ackermann O 1.8 mm) and limitations of the bar extension length (6 mm for the Ackermann O 1.8 mm, 8 mm for the Dolder-Y macro) allowed the bars to exceed 5 × 10 6 cycles of 120 and 250 N, respectively, before fracture. The region of highest stresses in FEA corresponded well with the locations of the fractures observed in static- and fatigue-testing. Conclusions With some simple guidelines/modifications, the number of bar extension fractures can be reduced significantly. Clinical significance This study focusses on distal bar extensions which improve the positioning of an implant supported overdenture. By combining laboratory testing and finite element simulations we aim to: (1) explain why fractures occur (dependent on physical characteristics of the bar), and (2) give clinical guidelines on how to prevent such fractures.

Some investigators suggest a similarity between the oral microbiota of dogs and humans. The in vivo assessment of ecologic relationships among bacterial species and between bacterial species and their habitat is difficult to carry out. Consequently, this aspect is often neglected in animal oral microbiological studies. This study aimed to examine the proportions of 40 bacterial species in samples from five intra-oral habitats in beagle dogs using checkerboard DNA-DNA hybridization. Microbial samples were taken from subgingival and supra-gingival plaque, the tongue, tonsils and cheek mucosa in seven beagle dogs. Samples were individually evaluated for their content of 40 bacterial species and the percentage of total DNA probe count was determined for each species, at each habitat. All tested species could be detected in all sampled habitats but each habitat had a distinct community structure. The microbiotas colonizing the hard surfaces in the oral cavity were quite different from the microbiotas colonizing the soft tissues. Bacterial species that are in humans considered to be periodontopathogens are present in high proportions. This study underlines the importance of the habitat and the host on the local microbial profile. (c) 2007 Elsevier B.V. All rights reserved. ispartof: Veterinary microbiology vol:127 issue:1 pages:79-88 ispartof: location:Netherlands status: published

Summary Although the available literature with its large variation in quality and criteria does not easily allow one to draw many firm conclusions, some common findings can be traced. The use of autogenous onlay blocks placed together with self-tapping implants can achieve an excellent long-term success rate of individual implants. Autogenous bone chips can be used to deal with fenestration and dehiscence defects when used in combination with e-PTFE membranes. (D)FDBA has been used as particulate material and in conjunction with barrier membranes. Although these allografts do not compare favorably with autogenous bone chips, their role as space maintainers under barrier membranes cannot be ignored. Demineralized bovine bone offers excellent osseoconductive properties. It can secure a predictable fill of intrabony defects on its own, whereas for bone augmentation in dehiscence and fenestration defects it should be used in combination with a membrane. Its slow resorption makes it more favorable for use with rather than before implant placement. Thus far the e-PTFE membranes, GTAM and TR-GTAM, are best documented. They offer reliable results, except for vertical augmentation procedures, in which exposure is regularly encountered (approximately 15%). The use of a collagen membrane when supported by a bone substitute to maintain the space gives good results, although the clinical data are still limited. The clinician should evaluate the eventual benefit of GBA, namely to be able to harbor longer implants with a better prognosis, versus the drawbacks and risks involved with the use of either bone substitutes or membranes.

Objectives The roughness of intraoral hard surfaces can influence bacterial plague retention. The present review evaluates the initial surface roughness of several intraoral hard materials, as well as changes in this surface roughness as a consequence of different treatment modalities. Methods Articles found through Medline searches were included in this review if they met the following criteria: 1) stated threshold surface roughness values and reputed change in surface roughness due to different manipulation techniques; or 2) included standardized surface conditions that could be compared to the treated surface. Results Recently, some in vivo studies suggested a threshold surface roughness for bacterial retention (R a = 0.2 μm) below which no further reduction in bacterial accumulation could be expected. An increase in surface roughness above this threshold roughness, however, resulted in a simultaneous increase in plaque accumulation, thereby increasing the risk for both caries and periodontal inflammation. The initial surface roughness of different dental materials ( e.g. , teeth, abutments, gold, amalgam, acrylic resin, resin composite, glass ionomer or compomer and ceramics) and the effect of different treatment modalities ( e.g. , polishing, scaling, brushing, condensing, glazing or finishing) on this initial surface roughness were analyzed and compared to the threshold surface roughness of 0.2 μm. The microbiological effects of these treatment modalities, if reported, are also discussed and compared to recent in vivo data. Significance Based on this review, the range in surface roughness of different intraoral hard surfaces was found to be wide, and the impact of dental treatments on the surface roughness is material-dependent. Some clinical techniques result in a very smooth surface (compressing of composites against matrices), whereas others made the surface rather rough (application of hand instruments on gold). These findings indicated that every dental material needs its own treatment modality in order to obtain and maintain a surface as smooth as possible.

Thirty-six edentulous patients, each provided with two Brȧnemark implants in the mandible to anchor an overdenture, were selected for this study and randomly divided into three groups of 12 patients each. In each group a different attachment system was used: (1) magnets, (2) ball attachments, and (3) straight bars with clips (control). The mean loading time was 12.4 months (range 3 to 24 months). This study investigated (1) the clinical behavior of loaded implants by means of overdentures related to their connection system (splinted versus unsplinted) and (2) the clinical performance of prosthetic treatment. Preliminary results indicate no differences; no failures occurred and the level of marginal bone height, as well as the probing attachment level, changed similarly in the three groups. Although splinted bar-retained overdentures scored better objectively, subjective satisfaction ratings did not differ. It was concluded that for the short follow-up period, the state of connection did not influence the clinical success of implants. However, no definite conclusions may be drawn until long-term data become available.

Previous clinical studies illustrated a positive correlation between the rate of “supragingival” plaque maturation and both the free energy and roughness of the intraoral hard surfaces (teeth, prostheses, implants). The present review of the literature aims to examine the clinical importance of these parameters especially in the “subgingival” environment, where plaque causes periodontitis. Despite the clear cut differences between supragingival and subgingival environments (with more possibilities for adhesion and fewer removal forces for the latter), both the surface roughness and the surface free energy remain important. This could be proven in an in vivo study in patients with implant-supported prostheses, where abutments (trans-mucosal connections between implant in the bone and prosthetic reconstruction) with different surface characteristics were examined. After an undisturbed subgingival plaque formation of 3 months, the roughened surfaces harboured significantly more bacteria (51 × 10 4 colony-forming units (CFU)) than both smooth abutments (3 × 10 4 CFU), and fluorinated ethylene-propylene (FEP) coated abutments with comparable roughness (11 × 10 4 CFU). The plaque composition was also slightly surface dependent, with a more pathogenic situation around the roughened titanium abutments. However, if the “in the pocket swimming flora” was considered, most differences disappeared.

In the oral cavity, which may be considered as an open growth system, most bacteria can only survive if they adhere to the hard surfaces (teeth, filling materials, dental implants, or prostheses). Such bacterial adhesion occurs in four phases: transport to the surface, initial adhesion with a reversible and irreversible stage, attachment by specific interactions and finally colonization. During this process the roughness and the free energy of the surfaces play a key role. The reduction in roughness of a surface will result in a dramatic retardation of plaque formation and maturation. A reduction in surface free energy of the substratum will result in a decrease in plaque growth rate, a decrease in plaque retention capacity of the surface and in the selection of specific organisms. Although both parameters interact with each other, the influence of surface roughness is dominant. The importance of both parameters justifies the demand for smooth surfaces with a low surface free energy in order to prevent plaque formation, thereby reducing the occurrence of gingival inflammation.

Ninety-one consecutive edentulous patients who had been treated by means of fixed prostheses (n = 103) supported by Branemark implants ( n = 589) were examined. Eighteen fixtures (3%) failed to integrate. After a mean loading time of 32 (range 6 to 80) and 38 months (range 5 to 83) for fixtures in the maxilla and mandible, respectively, an additional 12 fixtures lost integration. The cumulative failure rate for individual fixtures after 6 years was 8.4% and 5% for maxillae and mandibles, respectively. Only one patient had to revert to complete dentures. For fixtures in the maxillae, the mean marginal bone loss was 0.7, 0.1, and 0.2 mm for each of the first 3 years of loading, respectively; for fixtures in mandibles, the corresponding values were 0.7, 0.2, and 0.1 mm. The loss in marginal bone height was equal in both jaws and was not related to bleeding on probing or to the preoperative resorption anatomy.

Purpose This randomized controlled clinical trial aimed to evaluate the efficacy of splinted implants versus unsplinted implants in overdenture therapy over a 10-year period. Materials and Methods The study sample comprised 36 completely edentulous patients, 17 men and 19 women (mean age 63.7 years). In each patient, 2 implants (Branemark System, Nobel Biocare, Goteborg, Sweden) were placed in the interforaminal area. Three to 5 months after placement, they were connected to standard abutments. The patients were then rehabilitated with ball-retained overdentures, magnet-retained overdentures, or bar-retained overdentures (the control group). Patients were followed for 4, 12, 60, and 120 months post–abutment connection. Group means as well as linear regression models were fitted with attachment type and time as classification variables and corrected for simultaneous testing (Tukey). Results After 10 years, 9 patients had died and 1 was severely ill. Over 10 years, no implants failed. Mean Plaque Index, Bleeding Index, change in attachment level, Periotest values, and marginal bone level at the end of the follow-up period were not significantly different among the groups. Discussion The annual marginal bone loss, excluding the first months of remodeling, was comparable with that found around healthy natural teeth. Conclusion The fact that no implants failed and that overall marginal bone loss after the first year of bone remodeling was limited suggested that implants in a 2-implant mandibular overdenture concept have an excellent prognosis in this patient population, irrespective of the attachment system used.— Reprinted with permission of Quintessence Publishing.

Purpose This study aimed to compare the prosthetic aspects and patient satisfaction with prosthetic care in two-implant-retained mandibular overdentures, whether implants were splinted with a bar or left with magnets or ball attachments. Materials and methods Thirty-six completely edentulous patients had two Branemark implants placed in the mandibular canine area. A randomized procedure allocated patients into three groups of equal size, each with a different attachment system: bars, magnets, or balls. Prosthesis retention and mechanical as well as soft tissue complications were recorded in addition to patient satisfaction. A linear mixed model was fitted with attachment type and time as classification variables and adjusted by Turkey's multiple range test. Results Ball-retained overdentures showed at year 10 the greatest vertical retention force (1,327 g), followed by bars (1,067 g) and magnets (219 g). In the ball group, need for tightening of abutment screws was the most common mechanical complication; in the magnet and bar groups, respectively, the most common complications were wear and corrosion, and the need for clip activation. Prosthesis stability and chewing comfort for the overdenture were rated significantly lower for the magnet group compared to the ball and bar groups. Prosthesis stability of the maxillary denture was rated significantly lower in the bar group compared to ball and magnet groups. Conclusion The ball group scored best in relation to retention of the overdenture, soft tissue complications, and patient satisfaction at year 10. The bar group scored lower for comfort and stability of the maxillary denture. Magnets offered patients the least comfort. —Reprinted with permission of Quintessence Publishing.