Tobacco‐product usage as a risk factor for dental implants

The oral cavities of tobacco smokers and users of smokeless tobacco products are exposed to high concentrations of nicotine. A limited number of animal studies have assessed the effect of nicotine on osseointegration. Results from experimental studies have reported a statistically significant decrease, at 4 weeks of follow‐up, in bone‐to‐implant contact among rats exposed to nicotine compared with unexposed rats. Nicotine increases the production of inflammatory cytokines (such as interleukin‐6 and tumor necrosis factor‐alpha) by osteoblasts. Waterpipe, pipe, and cigarette smokers are at increased risk of developing oral cancer, periodontal disease, and alveolar bone loss. One explanation for this is that smokers (regardless of the type of tobacco product) are exposed to similar chemicals, such as nicotine, tar, oxidants, polyaromatic hydrocarbons, and carbon monoxide. Moreover, raised levels of proinflammatory cytokines have been identified in the gingival crevicular fluid of cigarette smokers with peri‐implant diseases. Therefore, it is hypothesized that nicotine and chemicals in tobacco smoke induce a state of oxidative stress in peri‐implant tissues (gingiva and alveolar bone), thereby increasing the likelihood of peri‐implant disease development via an inflammatory response, which if left uncontrolled, will result in implant failure/loss. In this regard, tobacco smoking (including cigarettes, waterpipe, and pipe) is a significant risk factor for peri‐implant diseases. The impact of vaping electronic cigarettes using nicotine‐containing e‐juices remains unknown. Habitual use of smokeless tobacco products is associated with oral inflammatory conditions, such as oral precancer, cancer, and periodontal disease. However, the effect of habitual use of smokeless tobacco products on the success and survival of dental implants remains undocumented.     

Analysis of cathepsin-K activity at tooth and dental implant sites and the potential of this enzyme in reflecting alveolar bone loss

Background: Cathepsin‐K is an enzyme involved in bone metabolism which may make this feature important for both natural teeth and dental implants. The aims of the present study are to comparatively analyze the gingival crevicular fluid (GCF)/peri‐implant sulcus fluid (PISF) cathepsin‐K levels of natural teeth and dental implants, and to assess the potential relationship between this biochemical parameter and alveolar bone loss around natural teeth and dental implants. Methods: Probing depth, bleeding on probing, gingival index, and plaque index clinical parameters were assessed, and GCF/PISF samples were obtained from natural teeth/dental implants presenting with either clinical health, gingivitis/peri‐implant mucositis, or chronic periodontitis/peri‐implantitis. Cathepsin‐K activity levels of 42 GCF samples and 54 PISF samples were determined, and marginal bone loss (MBL) measures were calculated from digitalized standardized intraoral periapical radiographs obtained from natural teeth and dental implants by using cemento‐enamel junction and the actual distance between two consecutive threads of the dental implant as reference points for natural teeth and dental implants, respectively. Results: Comparing the natural teeth group with dental implant group with regard to MBL measure, cathepsin‐K activity, and GCF/PISF volume revealed no significant differences. In both natural teeth and dental implant groups, despite higher MBL measures, cathepsin‐K activity, and GCF/PISF volumes with the presence of inflammation, it was the presence of alveolar bone loss that lead to significantly higher values for these parameters. Conclusion: We suggest cathepsin‐K as a biochemical parameter for monitoring periodontal/peri‐implant alveolar bone loss.     

Implant surface roughness and patient factors on long‐term peri‐implant bone loss

Dental implant placement is a common treatment procedure in current dental practice. High implant survival rates as well as limited peri‐implant bone loss has been achieved over the past decades due to continuous modifications of implant design and surface topography. Since the turn of the millennium, implant surface modifications have focused on stronger and faster bone healing. This has not only yielded higher implant survival rates but also allowed modifications in surgical as well as prosthetic treatment protocols such as immediate implant placement and immediate loading. Stable crestal bone levels have been considered a key factor in implant success because it is paramount for long‐term survival, aesthetics as well as peri‐implant health. Especially during the past decade, clinicians and researchers have paid much attention to peri‐implant health and more specifically to the incidence of bone loss. This could furthermore increase the risk for peri‐implantitis, the latter often diagnosed as ongoing bone loss and pocket formation beyond the normal biological range in the presence of purulence or bleeding on probing. Information on the effect of surface topography on bone loss or peri‐implantitis, a disease process that is to be evaluated in the long‐term, is also scarce. Therefore, the current narrative review discusses whether long‐term peri‐implant bone loss beyond physiological bone adaptation is affected by the surface roughness of dental implants. Based on comparative studies, evaluating implants with comparable design but different surface roughness, it can be concluded that average peri‐implant bone loss around the moderately rough and minimally rough surfaces is less than around rough surfaces. However, due to the multifactorial cause for bone loss the clinical impact of surface roughness alone on bone loss and peri‐implantitis risk seems rather limited and of minimal clinical importance. Furthermore, there is growing evidence that certain patient factors, such as a history of periodontal disease and smoking, lead to more peri‐implant bone loss.     

Periodontal and peri‐implant wound healing following laser therapy

Laser irradiation has numerous favorable characteristics, such as ablation or vaporization, hemostasis, biostimulation (photobiomodulation) and microbial inhibition and destruction, which induce various beneficial therapeutic effects and biological responses. Therefore, the use of lasers is considered effective and suitable for treating a variety of inflammatory and infectious oral conditions. The CO₂, neodymium‐doped yttrium‐aluminium‐garnet (Nd:YAG) and diode lasers have mainly been used for periodontal soft‐tissue management. With development of the erbium‐doped yttrium‐aluminium‐garnet (Er:YAG) and erbium, chromium‐doped yttrium‐scandium‐gallium‐garnet (Er,Cr:YSGG) lasers, which can be applied not only on soft tissues but also on dental hard tissues, the application of lasers dramatically expanded from periodontal soft‐tissue management to hard‐tissue treatment. Currently, various periodontal tissues (such as gingiva, tooth roots and bone tissue), as well as titanium implant surfaces, can be treated with lasers, and a variety of dental laser systems are being employed for the management of periodontal and peri‐implant diseases. In periodontics, mechanical therapy has conventionally been the mainstream of treatment; however, complete bacterial eradication and/or optimal wound healing may not be necessarily achieved with conventional mechanical therapy alone. Consequently, in addition to chemotherapy consisting of antibiotics and anti‐inflammatory agents, phototherapy using lasers and light‐emitting diodes has been gradually integrated with mechanical therapy to enhance subsequent wound healing by achieving thorough debridement, decontamination and tissue stimulation. With increasing evidence of benefits, therapies with low‐ and high‐level lasers play an important role in wound healing/tissue regeneration in the treatment of periodontal and peri‐implant diseases. This article discusses the outcomes of laser therapy in soft‐tissue management, periodontal nonsurgical and surgical treatment, osseous surgery and peri‐implant treatment, focusing on postoperative wound healing of periodontal and peri‐implant tissues, based on scientific evidence from currently available basic and clinical studies, as well as on case reports.     

Prognostic factors for alveolar regeneration: bone formation at teeth and titanium implants

OBJECTIVES: There is a limited understanding of the effect of defect characteristics on alveolar bone healing. The objectives of this study were to assess the effect of alveolar bone width and space provision on bone regeneration at teeth and titanium implants, and to test the hypothesis that the regenerative potentials at teeth and implants are not significantly different. METHODS: Critical size, 5-6-mm, supra-alveolar, periodontal defects were surgically created in 10 young adult dogs. Similarly, critical size, 5-mm, supra-alveolar, peri-implant defects were created in four dogs. A space-providing expanded polytetrafluoroethylene device was implanted for guided tissue regeneration/guided bone regeneration. The animals were euthanized at 8 weeks postsurgery. Histometric analysis assessed alveolar bone regeneration (height) relative to space provision by the device and the width of the alveolar crest at the base of the defect. Statistical analysis used the linear mixed models. RESULTS: A significant correlation was found between bone width and wound area (r=0.55892, p<0.0001). Generally, bone width and wound area had statistically significant effects on the extent of bone regeneration (p<0.0005 and p<0.0001, respectively). Bone regeneration was linearly correlated with the bone width at periodontal (p<0.001) and implant (p=0.04) sites, and with the wound area at periodontal (p<0.0001) and implant (p=0.03) sites. The relationships of bone regeneration with these two variables were not significantly different between teeth and implants (bone width: p=0.83; wound area: p=0.09). When adjusted for wound area, bone regeneration was significantly greater at periodontal than at implant sites (p=0.047). CONCLUSIONS: The horizontal dimension of the alveolar bone influences space provision. Space provision and horizontal dimension of the alveolar bone appear to be important determinants of bone regeneration at teeth and implants. The extent of alveolar bone formation at implant sites is limited compared with that at periodontal sites.     

Treatment of pathologic peri‐implant pockets

Peri‐implant and periodontal pockets share a number of anatomical features but also have distinct differences. These differences make peri‐implant pockets more susceptible to trauma and infection than periodontal pockets. Inadequate maintenance can lead to infections (defined as peri‐implant mucositis and peri‐implantitis) within peri‐implant pockets. These infections are recognized as inflammatory diseases, which ultimately lead to the loss of supporting bone. Diagnostic and treatment methods conventionally used in periodontics have been adopted to assess and treat these diseases. Controlling infection includes elimination of the biofilm from the implant surface and efficient mechanical debridement. However, the prosthetic supra‐structure and implant surface characteristics can complicate treatment. Evidence shows that when appropriately managed, peri‐implant mucositis is reversible. Nonsurgical therapy, with or without the use of antimicrobials, will occasionally resolve peri‐implantitis, but for the majority of advanced lesions this approach is insufficient and surgery is indicated. The major objective of the surgical approach is to provide access and visualize the clinical situation. Hence, a more informed decision can be made regarding whether to use a resective or a regenerative surgical technique. Evidence shows that following successful decontamination, surgical treatment to regenerate the bone can be performed, and a number of regenerative techniques have been proposed. After treatment, regular maintenance and good oral hygiene are essential for a predictable outcome and long‐term stability.     

Reliability of periodontal diagnostic tools for monitoring peri‐implant health and disease

The prevalence, causes and consequences of crestal bone loss at dental implants are a matter of debate. In recent years, a high prevalence of peri‐implant soft‐tissue inflammation, associated with peri‐implant bone loss, has been reported and the need for treatments similar to those offered for natural teeth affected by periodontitis has been proposed. This suggestion is based on the assumption that periodontal indices, such as probing pocket depth and bleeding on probing, are reliable indicators of the peri‐implant tissue conditions and good predictors of future bone loss. However, based on a critical review of the literature in the present paper, it is concluded that periodontal indices are not reliable either for identifying peri‐implant disease or for predicting future risk for peri‐implant crestal bone loss and implant failure. The long‐term experiences with dental implants, presented in the literature, indicate that the presence of bleeding on probing, probing pocket depths much larger than 4 mm and some bone loss seem to reflect, in most instances, normal conditions of well‐functioning dental implants, bearing in mind that healing of dental implants is the result of a foreign body reaction with the formation of scar tissue. Therefore, the use of probing pocket depth and bleeding on probing assessments may lead to over‐diagnosis and possibly to over‐treatment of assumed biofilm‐mediated peri‐implantitis lesions. It is the opinion of the authors of this review that a treatment should only be initiated when a clinical problem is present based on patient's symptoms (discomfort, pain), the presence of swelling, redness and pus, and significant crestal bone loss over time (as verified with radiographs). The treatment should aim at resolving the infection, which could include removal of the implant.     

Food Impaction and Periodontal/Peri‐Implant Tissue Conditions in Relation to the Embrasure Dimensions Between Implant‐Supported Fixed Dental Prostheses and Adjacent Teeth: A Cross‐Sectional Study

Background: Food impaction and periodontal/peri‐implant tissue conditions were evaluated in relation to the embrasure dimensions between implant‐supported fixed dental prostheses (FDPs) and adjacent teeth. Methods: A total of 215 embrasures of 150 FDPs in 100 patients (55 males and 45 females, aged 27 to 83 years; mean age: 56 years) were included in the study. Clinical assessments of the periodontal/peri‐implant mucosal conditions, radiographic assessments of embrasure dimensions, and overall patient satisfaction were used as explanatory variables for the food impaction and periodontal/peri‐implant tissue conditions adjacent to implant‐supported FDPs in the generalized estimating equation (GEE) analysis. Results: Food impaction was reported in 96 (44.7%) of 215 embrasures between implant‐supported FDPs and adjacent teeth. Food impaction was reported more frequently in the embrasures with proximal contact loss than in those with tight contact (P = 0.009). Overall patient satisfaction was influenced negatively by food impaction in the proximal embrasures (P = 0.01). Among embrasure dimensions, only the embrasure surface area (ESA) significantly influenced food impaction (P = 0.03). Significant influences of various embrasure dimensions on the periodontal/peri‐implant mucosal conditions and bone level at the implant were found in the univariate and multivariate GEE analyses. Conclusions: Food impaction between implant‐supported FDPs and adjacent teeth occurred more frequently when proximal contact was lost and ESA increased. Food impaction negatively affected overall patient satisfaction. Embrasure dimensions influenced the periodontal/peri‐implant mucosal conditions and bone level at the implant.     

General genetic and acquired risk factors,and prevalence of peri‐implant diseases – Consensus report of working group 1

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.     

Periodontal diseases and osteoporosis: association and mechanisms

There is increasing evidence that osteoporosis, and the underlying loss of bone mass characteristic of this disease, is associated with periodontal disease and tooth loss. Periodontitis has long been defined as an infection-mediated destruction of the alveolar bone and soft tissue attachment to the tooth, responsible for most tooth loss in adult populations. Current evidence including several prospective studies supports an association of osteoporosis with the onset and progression of periodontal disease in humans. The majority of studies have shown low bone mass to be independently associated with loss of alveolar crestal height and tooth loss. However studies that focus on the relation of clinical attachment loss and osteoporosis are less consistent. To date, the majority of studies on the relationship between periodontal disease and osteoporosis have been hindered by small sample sizes, limited control of other potential confounding factors, varying definitions of both periodontal disease and osteoporosis, and few prospective studies where the temporality of the association can be established. Potential mechanisms by which host factors may influence onset and progression of periodontal disease directly or indirectly include underlying low bone density in the oral cavity, bone loss as an inflammatory response to infection, genetic susceptibility, and shared exposure to risk factors. Systemic loss of bone density in osteoporosis, including that of the oral cavity, may provide a host system that is increasingly susceptible to infectious destruction of periodontal tissue. Studies have provided evidence that hormones, heredity, and other host factors influence periodontal disease incidence and severity. Both periodontal disease and osteoporosis are serious public-health concerns in the United States. Prevalence of both osteoporosis and tooth loss increase with advancing age in both women and men. Understanding the association between these common diseases and the mechanisms underlying those associations will aid health professionals to provide improved means to prevent, diagnose, and treat these very common diseases. This paper reviews the current evidence on the association between periodontal disease and osteoporosis.     

Periodontal and peri‐implant diseases: identical or fraternal infections?

Peri‐implant diseases (peri‐implantitis and peri‐implant mucositis) are bacterially driven infections. Peri‐implantitis leads to aggressive bone resorption and eventual loss of the implant. Traditionally, peri‐implantitis was regarded as microbially similar to periodontitis, and translocation of periodontal pathogens into the peri‐implant crevice was considered as a critical factor in disease causation. However, evidence is emerging to suggest that the peri‐implant and periodontal ecosystems differ in many important ways. The purpose of this review is to examine the evidence supporting microbial congruence and discordance in these two communities. Current evidence suggests that osseointegrated implants truly create unique microenvironments that force microbial adaptation and selection. Further studies that revisit the “microbial reservoir” hypothesis and identify species that play an etiologic role in peri‐implant disease and examine their transmission from teeth are needed.     

Implant Abutment Cleaning by Plasma of Argon: 5‐Year Follow‐Up of a Randomized Controlled Trial

Background: Contamination of implant abutments could potentially influence the peri‐implant tissue inflammatory response. The aim of the present study is to assess the radiographic bone changes around customized, platform‐switched abutments placed according to the “one‐abutment‐one‐time” protocol, with and without plasma of argon cleaning treatment. Methods: Thirty healthy patients with thin gingival biotype (<1 mm) and history of periodontal disease received one maxillary implant each. Immediately before abutment connection, patients were randomly assigned to control group (cleaning protocol by steaming) or test group (plasma of argon treatment). Outcome measures were: 1) success rate of implants and prostheses; 2) biologic and prosthetic complications; 3) peri‐implant marginal bone loss (MBL); 4) esthetic and periodontal parameters; and 5) patient satisfaction. Results: Neither implants nor prostheses were lost in either group at the 5‐year follow‐up examination. Overall, both groups showed a slight amount of peri‐implant bone loss from baseline to 5 years. A statistically higher mean MBL was found in the control group compared with the test group at 6, 24, and 60 months after crown connection. Nevertheless, during the entire follow‐up period, intragroup comparison demonstrated statistically significant mean MBL in the control group, but not in the test group. The test group showed a higher mean gain at the soft tissue margin, but not for the papilla. All implants showed good periodontal parameters, with no significant differences between groups. Conclusion: Plasma of argon could be used to disinfect implant abutments before insertion to minimize future peri‐implant bone resorption.     

Cementogenesis and the induction of periodontal tissue regeneration by the osteogenic proteins of the transforming growth factor-beta superfamily

Theantiquity and severity of periodontal diseases are demonstrated by the hard evidence of alveolar bone loss in gnathic remains of the Pliocene/Pleistocene deposits of the Bloubank Valley at Sterkfontein, Swartkrans and Kromdrai in South Africa. Extant Homo has characterized and cloned a superfamily of proteins which include the bone morphogenetic proteins that regulate tooth morphogenesis at different stages of development as temporally and spatially connected events. The induction of cementogenesis, periodontal ligament and alveolar bone regeneration are regulated by the co-ordinated expression of bone morphogenetic proteins. Naturally derived and recombinant human bone morphogenetic proteins induce periodontal tissue regeneration in mammals. Morphological analyses on undecalcified sections cut at 3–6 μm on a series of mandibular molar Class II and III furcation defects induced in the non-human primate Papio ursinus show the induction of cementogenesis. Sharpey's fibers nucleate as a series of composite collagen bundles within the cementoid matrix in close relation to embedded cementocytes. Osteogenic protein-1 and bone morphogenetic protein-2 possess a structure–activity profile, as shown by the morphology of tissue regeneration, preferentially cementogenic and osteogenic, respectively. In Papio ursinus , transforming growth factor-β₃ also induces cementogenesis, with Sharpey's fibers inserting into newly formed alveolar bone. Capillary sprouting and invasion determine the sequential insertion and alignment of individual collagenic bundles. The addition of responding stem cells prepared by finely mincing fragments of autogenous rectus abdominis muscle significantly enhances the induction of periodontal tissue regeneration when combined with transforming growth factor-β₃ implanted in Class II and III furcation defects of Papio ursinus .     

Long‐Term Effect of Surface Roughness and Patients' Factors on Crestal Bone Loss at Dental Implants. A Systematic Review and Meta‐Analysis

Publications from 2011 to 2015 were selected to evaluate effect of implant surface roughness on long‐term bone loss as surrogate for peri‐implantitis risk. 87 out of 2,566 papers reported the mean bone loss after at least 5 years of function. Estimation of the proportion of implants with bone loss above 1, 2, and 3 mm as well as analysis the effect of implant surface roughness, smoking, and history of periodontitis was performed. By means of the provided statistical information of bone loss (mean and standard deviation) the prevalence of implants with bone loss ranging from 1 to 3 mm was estimated. The bone loss was used as a surrogate parameter for “peri‐implantitis” given the fact that “peri‐implantitis” prevalence was not reported in most studies or when reported, the diagnostic criteria were unclear or of dubious quality. The outcome of this review suggests that peri‐implant bone loss around minimally rough implant systems was statistically significant less in comparison to the moderately rough and rough implant systems. No statistically significant difference was observed between moderately rough and rough implant systems. The studies that compared implants with comparable design and different surface roughness, showed less average peri‐implant bone loss around the less rough surfaces in the meta‐analysis. However, due to the heterogeneity of the papers and the multifactorial cause for bone loss, the impact of surface roughness alone seems rather limited and of minimal clinical importance. Irrespective of surface topography or implant brand, the average weighted implant survival rate was 97.3% after 5 years or more of loading. If considering 3 mm bone loss after at least 5 years to represent the presence of “peri‐implantitis,” less than 5% of the implants were affected. The meta‐analysis indicated that periodontal history and smoking habits yielded more bone loss.     

表观遗传学及其调控与牙周病

表观遗传学是指不涉及DNA序列改变,而是通过有丝分裂和减数分裂进行遗传的基因表达变化的遗传学分支学科,其调控机制主要包括DNA甲基化、组蛋白修饰、染色质重塑和非编码RNA调控等.牙周炎病因复杂,且被吸收、破坏的牙槽骨很难实现功能性再生.表观遗传学在导致炎症的发生及促进骨再生的过程中扮演着重要角色,从表观遗传学及其调控的角度来预防牙周病的发生,促进牙槽骨的功能性再生,将是未来重要的研究内容,具有重要的临床意义.     

Impact of excessive occlusal load on successfully‐osseointegrated dental implants: a literature review

The aim of the present study was to review the available evidence on the response of the peri‐implant bone when subjected to excessive occlusal forces. The search strategy included papers published in English in the Medline database and the Wiley Online Library from January 1991 to December 2011. Experimental or review papers reporting the conditions of the peri‐implant bone of dental implants submitted to excessive occlusal loading in the presence of a controlled oral hygiene regime were eligible for inclusion. The knowledge regarding the response of the peri‐implant bone when the dental implant is excessively loaded is limited, and the level of evidence is poor. With animal experimental studies showing conflicting results, it is unclear whether occlusal overload might cause marginal bone loss or total loss of osseointegration to already osseointegrated dental implants when the applied load exceeds the biologically‐acceptable limit. This biological limit is also unknown. Furthermore, higher remodeling activity of the peri‐implant bone is found around implants subjected to high loading forces.     

Animal models for periodontal regeneration and peri‐implant responses

Translation of experimental data to the clinical setting requires the safety and efficacy of such data to be confirmed in animal systems before application in humans. In dental research, the animal species used is dependent largely on the research question or on the disease model. Periodontal disease and, by analogy, peri‐implant disease, are complex infections that result in a tissue‐degrading inflammatory response. It is impossible to explore the complex pathogenesis of periodontitis or peri‐implantitis using only reductionist in‐vitro methods. Both the disease process and healing of the periodontal and peri‐implant tissues can be studied in animals. Regeneration (after periodontal surgery), in response to various biologic materials with potential for tissue engineering, is a continuous process involving various types of tissue, including epithelia, connective tissues and alveolar bone. The same principles apply to peri‐implant healing. Given the complexity of the biology, animal models are necessary and serve as the standard for successful translation of regenerative materials and dental implants to the clinical setting. Smaller species of animal are more convenient for disease‐associated research, whereas larger animals are more appropriate for studies that target tissue healing as the anatomy of larger animals more closely resembles human dento‐alveolar architecture. This review focuses on the animal models available for the study of regeneration in periodontal research and implantology; the advantages and disadvantages of each animal model; the interpretation of data acquired; and future perspectives of animal research, with a discussion of possible nonanimal alternatives. Power calculations in such studies are crucial in order to use a sample size that is large enough to generate statistically useful data, whilst, at the same time, small enough to prevent the unnecessary use of animals.     

Clinical and Radiological Outcomes of Two Implants with Different Prosthetic Interfaces and Neck Configurations: Randomized,Controlled, Split‐Mouth Clinical Trial

Background: Peri‐implant bone loss seems to occur following implant placement/loading regardless of all the efforts to eliminate it. Several factors, including surgical trauma, biologic width establishment, lack of passive fit of the superstructures, implant‐abutment microgap, and occlusal overloading, may increase peri‐implant bone loss. Over the years, new interface designs were introduced and clinical studies suggest that internal conical connection and platform shifting may be advantageous for marginal bone preservation. Purpose: To compare clinical and radiological outcomes of two implant designs with different prosthetic interfaces and neck configurations in a randomized, controlled, split‐mouth clinical trial. Materials and Methods: Thirty‐four partially edentate patients randomly received at least one internal conical connection with back‐tapered collar and platform shifting design or external‐hexagon implants with flat‐to‐flat implant‐abutment interface. Primary end point was peri‐implant bone level changes at different time points, failures of implants and/or prosthesis, any complications, implant stability quotient (ISQ) values, and periodontal parameters. Results: No dropout occurred. Marginal bone changes were statistically significantly different with better results for the internal conical connection. No implants and prosthesis failures have been observed, yielding a cumulative survival rate of 100%. A high ISQ value was found for both implants, and no statistically significant difference was found for ISQ mean values between interventions at each time point (p > .05). All implants showed no bleeding on probing and a very slight amount of plaque at the 1‐year‐in‐function visit. Conclusions: Both implant designs investigated performed similarly in terms of failure rates, providing successful results up to 1 year after loading. The back‐tapered neck configuration with conical connection and built‐in platform shifting showed statistically lower marginal bone loss than straight neck configuration with flat‐to‐flat implant‐abutment interface and external‐hexagonal connection.     

Influence of bony defects on implant stability

Introduction: The purpose of this study was to analyze the evolution of implant mechanical stability in different types/sizes of bony defects using both Periotest and Osstell devices as “objective tools.” Materials and methods: Thirty‐two implants were randomly allocated to one of the four types of bone defects: marginal bone loss, peri‐apical bone defect, constant width dehiscence and constant length dehiscences. Periotest/Osstell measurements were completed before and during staged bone removal (to enlarge defect size). Results: Significant differences (P<0.05) with initial values were found after a 2 mm marginal bone removal (Osstell/Periotest); for a peri‐apical bone lesion, after removal of 5 mm (Osstell) or 8 mm (Periotest); for a 6‐mm‐long dehiscence, after removal up to 180° of the implant perimeter (Osstell/Periotest); for a 3‐mm‐wide dehiscence, after removal of 10 mm (Osstell) or 6 mm (Periotest). Conclusion: Periotest and Osstell are in general not very sensitive in the identification of peri‐implant bone destruction, except for marginal bone loss. To cite this article:
Merheb J, Coucke W, Jacobs R, Naert I, Quirynen M. Influence of bony defects on implant stability.
Clin. Oral Impl. Res. 21 , 2010; 919–923.
doi: 10.1111/j.1600‐0501.2010.01932.x