Progressive Marginal Bone Loss Research Articles

Progressive bone loss and bleeding on probing: A cohort study.

To investigate whether a progressive marginal bone loss (PMBL) occurring beyond the initial bone remodeling (IBR) is linked with bleeding on probing. A total of 70 partially edentulous patients exhibiting 112 two-piece bone-level implants were included in this retrospective study. Panoramic radiographs were obtained after implant insertion (T0), after delivery of a final prosthetic restoration (T1) and subsequently during the 1-(T2), 5-(T3), 10-(T4), and 15-years (T5) follow-up visits. At each time point, radiographic marginal bone levels were assessed from the implant shoulder to the first bone-to-implant contact at mesial and distal aspects. The IBR was defined as a bone loss occurring up to prosthesis delivery, that is, from T0 to T1. The PMBL was defined as bone loss occurring after T1. At T2, T3, T4, and T5, the presence or absence of bleeding on probing (BOP) was recorded at four sites. A median regression with mixed models was performed to assess the difference of PMBL in PMBL + BOP+ and PBML + BOP- groups. Over the mean implant functioning time of 4.44 ± 4.91 years, 38 (34%) implants showed no PBML, whereas 74 (66%) implants featured PMBL. Of these, 35 (47%) and 39 (53%) implants were assigned to the PMBL + BOP- and PMBL + BOP+ groups, respectively. The mean PMBL after 1, 5, 10, and 15 years were comparable between implants featuring PMBL with or without BOP. At 1 year, BOP intensity significantly correlated PMBL, with each increase in one BOP-positive site being associated with increase in PMBL by 0.55 mm (p = 0.038), whereas this association was not found at 5, 10, and 15 years. The IBR values in the no PBML, PMBL + BOP+, and PBML + BOP- groups were -0.24 ± 0.31, -0.41 ± 0.59, and -0.24 ± 0.33 mm, respectively, with no significant differences found among the groups. Progressive bone loss at implant sites is not always linked with bleeding on probing.

Absence of Progressive Bone Loss Following Peri-Implantitis Surgical Therapy with Implantoplasty: A Case Series

Background: Peri-implantitis, a bacteria-associated inflammatory disease, is characterized by inflammation of the peri-implant mucosa and progressive loss of the supporting bone, thereby reducing the chances of dental implant survival. The absence of progressive marginal bone loss is crucial for implant success. The aim of this study is to assess the peri-implantitis resolution by measuring the absence of progressive bone loss rate around the implant over a period of one year to more than three years after surgical reconstructive (REC) treatment, apically repositioned flap (ARP) surgery, or combined (COM) treatment of peri-implantitis with implantoplasty. Methods: Peri-implantitis patients, that underwent surgical therapy with implantoplasty and that enrolled in a regular peri-implant supportive care program with a follow up of ≥12 months, were recruited in this study. ARP, REC, or COM surgical therapy was performed depending on the anatomy of the bone defect. For REC and COM groups, intraosseous defects were filled with a bone substitute. The ARP group consisted of an apically positioned flap without osseous surgery. Absence of progressive marginal bone loss was evaluated on radiographs of the treated implants. Results: A total of 57 patients (91 implants) were included. The study occurred over a follow-up period of 12 to 42 months (mean = 24 months). The surgical treatment with implantoplasty yielded an absence of progressive bone loss rate of 96.7% at implant level (100% REC, 98% COM, 92.9% ARP) and 96.5% at patient level. Three implants had to be removed in two patients due to relapse or progression of peri-implantitis. Conclusions: This case series demonstrated that implantoplasty during surgical treatment of peri-implantitis lesions resulted in favorable biological conditions to maintain functional implants with 96.7% of implants that did not show bone loss over time from one year to more than three years.

Patient-centered outcomes after surgical treatment of peri-implantitis: a prospective clinical study.

Peri-implantitis is an inflammatory process affecting soft and hard tissues surrounding dental implants, causing progressive marginal bone loss. Peri-implant surgery is the treatment of choice. However, evidence about its impact on patients' quality of life (QoL) is limited. This study aimed to assess pain and QoL in the first seven post-operative days and measure patient satisfaction at the end of this period. A prospective cohort study was conducted in patients with peri-implantitis. Patients reported pain on a visual analogue scale (VAS) ranging from 0 to 100mm every day during the first week after surgery. They then completed the OHIP-14sp questionnaire. A descriptive and inferential data analysis was used to assess the effect of surgical approach (resective, regenerative or combined), gender and working status on pain, satisfaction and QoL. Forty-one patients (93,2%) completed the daily pain VAS; scores ranged from 0 to 95 mm. Gender, occupation, or type of surgery had no significant effect upon its evolution. The mean total OHIP-14sp score was 16.7 (range = 5 to 33), indicating low to moderate deterioration in perceived oral health. Postoperative OHRQoL was significantly higher in working patients (mean difference (MD): 3.94; P = 0.042), and with the regenerative (MD: 6.34; P = 0.044) or the combined approach (MD: 5.41; P = 0.027). Considering the limitations of this study, postoperative pain was mild to moderate and decreased after the third day. Surgical treatment of peri-implantitis has an impact on QoL, especially when augmentation procedures are involved. This impact is higher in working patients.

Surgical interventions for the treatment of peri-implantitis.

Peri-implantitis constitutes one of the most frequent late dental implant complications. The disease is initiated by bacterial infection; therefore, anti-infective peri-implantitis treatment strategies are required to arrest the progressive marginal bone loss and maintain the affected implant in function. Although nonsurgical treatment strategies appear to be of limited predictability, treatment outcomes have been frequently improved following surgical interventions. The present narrative review describes various surgical peri-implantitis treatment modalities, with respect to their indications, performance, and effectiveness. The present narrative review considered the most relevant studies in the field published in the English language. Surgical peri-implantitis treatment approaches can be categorized as nonreconstrucive therapy, reconstructive therapy, and combined therapy (ie, reconstructive and resective therapy). In addition to disease resolution, reconstructive approaches also seek to regenerate the bone defect and achieve reosseointegration. The severity of the disease, the regenerative potential of the defetc and esthetic demands of the patient are the factors determining the surgical peri-implantitis treatment modality.

Impact of smoking on peri-implant bleeding on probing.

Studies around natural dentition demonstrated that smoking can reduce the tendency of inflamed tissue to bleed upon probing after controlling for possible confounders. In addition, previous research suggested that smokers may present alterations of the peri-implant microbiome. This study aimed at investigating the impact of smoking on: (1) peri-implant bleeding on probing (BOP; primary objective); (2) the association between BOP/bone loss and BOP/visible gingival inflammation; (3) peri-implant microbiome. Partially edentulous patients with implants restored with a single crowns were included in this study. Subjects were either smokers (≥1 cigarettes per day) or nonsmokers (never smokers). The primary outcome of this cross-sectional study was BOP and secondary outcomes included: Probing pocket depth (PPD), Modified gingival Index (mGI) and Progressive Marginal Bone Loss. In addition, microbial profiles of the subjects were assessed through sequencing of the 16S rRNA gene. Univariate and multilevel multivariate analyses by means of Generalized Estimating Equations were conducted to analyze the association between smoking and peri-implant BOP. Overall, 27 nonsmokers and 27 smokers were included and 96.3% and 77.78% of patients presented peri-implant BOP in the nonsmoker and smoker group, respectively (p =0.046). Smoking was inversely associated with BOP in the multivariate multilevel analysis (OR=0.356; 95% CI: 0.193-0.660; p =0.001) whereas a positive correlation was demonstrated for mGI > 0 (OR=3.289; 95% CI: 2.014-5.371; p < 0.001); PPD (OR=1.692; 95% CI: 0.263-0.883; p =0.039) and gender (OR=2.323; 95% CI: 1.310-4.120 p =0.004). A decrease of BOP sensitivity in detecting visible gingival inflammation (mGI > 0) was observed in smokers. Besides, taxonomic and changes in diversity regarding the peri-implant microbiota were detected comparing the two groups. Significantly higher richness of the microbiota was demonstrated in the smoker group when implants affected by peri-implantitis were compared to either healthy implants or implants presenting mucositis. Smoking is a potential modifier of BOP and peri-implant microbiota.

Long-term effectiveness of 6mm micro-rough implants in various indications: A 4.6- to 18.2-year retrospective study.

ObjectivesTo evaluate the long‐term effectiveness of 6 mm implants in various indications with a micro‐rough surface after 4.6–18.2 years in function and to assess key factors associated with implant survival, success, and biologic/technical complications.Materials and methodsFifty‐five patients with seventy‐four 6 mm implants placed from 2000 to 2013 attended the re‐examination assessing well‐established clinical and radiographic parameters, biologic and prosthetic complications, and patient‐reported outcome measures.ResultsFive implants were lost after a mean follow‐up period of 9.1 years resulting in a survival rate of 93.2%. All losses occurred in free‐end situations in the mandible. Smoking habit significantly reduced implant survival (hazard ratio 36.25). Two implants exhibited a history of peri‐implantitis, and one implant showed progressive marginal bone loss (MBL) resulting in a success rate of 89.2%. The mean MBL amounted to 0.029 mm. Increased MBL was found for implants placed in the maxilla (0.057 mm) and for implants with a diameter of 4.1 mm (0.043 mm). Soft tissue thickness (1.39 mm) and width of keratinized mucosa (1.91 mm) had no effect on MBL. Patient‐reported outcome measures showed high satisfaction (mean VAS scores 88%) and high quality of life (mean OHIP‐G14 score 2.2).ConclusionThe present study demonstrated survival and success rates of 93.2% and 89.2% for 6 mm implants used in various indications. A factor leading to higher implant failure was smoking, whereas modulating factors increasing annual MBL included implants placed in the maxilla and implants with a diameter of 4.1 mm compared to 4.8 mm.

Which is the best antibiotic prophylaxis protocol to prevent early implant failures?

Selection criteria The inclusion criteria of this systematic review were patients undergoing dental implant placement. Only randomised clinical trials (RCTs) that compared placebo, no antibiotic and/or any type of antibiotics, administered pre-operatively, intra-operatively, post-operatively or combinations of these, at any dose and for any duration were considered eligible. Included RCTs were required to have a follow up period of at least three months with at least 20 patients per treatment arm. No restrictions on date of publication or language were applied.Key study factor Four electronic databases (MEDLINE, SCOPUS, CENTRAL and Web of Knowledge) in addition to six related journals (Journal of Clinical Periodontology, Clinical Oral Implants Research, Clinical Implant Dentistry and Related Research, Journal of Periodontology, European Journal of Oral Implantology, International Journal of Oral & Maxillofacial Implants) were searched in duplicate for RCTs up to July 2017. Additional relevant literature was identified through hand-searching of reference lists, and through grey literature databases. Two independent reviewers screened the titles and abstracts . Data extraction and risk of bias assessment was performed simultaneously by two reviewers independently and in duplicate using the Cochrane tool for risk of bias assessment. A Network Meta-analysis (NMA) was conducted by integrating direct and indirect comparisons and the probability that each protocol was optimal was estimated. Subgroup and sensitivity analyses were planned to test the effect of risk of bias and of different variables on the results, but were not conducted due to the limited number of included studies.Main outcome measure Outcomes analysed were adverse events and early implant failures, defined as removal of mobile or stable implants with progressive marginal bone loss or infection in the first year after placement.Main results A total of 2248 RCTs were identified after removing duplicates, nine of which were finally included. Different protocols of antibiotic prophylaxis were compared with a total number of 1,693 participants. Seven of the included trials compared the use of one or more protocols of antibiotic prophylaxis with no prophylaxis or prophylaxis with a placebo, and two trials compared the use of different protocols, without the use of a no prophylaxis/placebo group. Amoxicillin was the only type used in all studies. Doses and timing varied among studies, although most of them used a single dose taken just before the implant placement. For the investigated outcomes, two trials were considered at low risk of bias and seven at high risk of bias.All protocols were more effective in reducing implant failures compared to placebo/no antibiotic (mean OR 0.08 to 0.45). Meta-analysis of direct comparison was only possible for the four trials comparing 2 g amoxicillin one hour preoperatively (B) to no antibiotic or placebo (A), indicating B as more effective (pulled OR = 0.40; 95% CI: 0.19-0.88; heterogeneity chi-squared 1.40, P = 0.706). These results were consistent with NMA effect estimates (mean OR = 0.45; 95% CI: 0.0210.93). A single dose of 3 g of amoxicillin administered one hour pre-operatively (C) was statistically more effective in reducing implant failures if compared to no prophylaxis/placebo (OR = 0.41, 95% CI = 0.180.91) and was considered as the most effective protocol. The single dose of 2 g of amoxicillin administered one hour pre-operatively was less effective than protocol C. Adverse events could not be studied in a meta-analysis due to an insufficient number of trials reporting it.Conlusions Implant patients are likely to benefit from antibiotis being administered one hour preoperatively in a dose of 3 g orally. The use of post-operative antibiotics does not seem, however, to be justified.

Two to six-year disease resolution and marginal bone stability rates of a modified resective-implantoplasty therapy in 32 peri-implantitis cases.

Different nonsurgical, antibacterial, surgical, and regenerative approaches to treat peri-implantitis have been proposed, but there is no an actual "gold" standard treatment showing the most favorable results to counteract peri-implantitis effects. To evaluate radiographically and clinically the disease resolution and peri-implant marginal bone stability rates of peri-implantitis cases treated through a combined resective-implantoplasty therapy in a moderate to long-term period. Records of patients diagnosed with peri-implantitis and treated through the same protocol applying a combined resective-implantoplasty therapy with minimum 2-year follow-up were screened. Eligible patients were contacted and asked to undergo clinical and radiologic examination. Progressive marginal bone loss, bleeding on probing, suppuration, implant mobility, and implant fracture were considered to establish the disease resolution rate and peri-implant bone stability of the treated implants. Twenty-three patients with 32 treated implants fulfilled the inclusion criteria. Over the 2 to 6-year follow-up, (mean time: 3.4 ± 1.5 years), the disease resolution rate was 83% (patient level) and 87% (implant level). Four implants (13%) were lost or removed due to continuous MBL and osseointegration failure. At follow-up, peri-implant marginal bone remained stable with no further bone loss in 87% of the treated implants. BOP was absent in 89.3% (implant level), suppuration was resolved in all cases, and no pain or implant fracture was reported. Implantoplasty treated cases showed high disease resolution rate and peri-implant marginal bone stability. This surgical antibiofilm strategy can counteract peri-implantitis progression providing an adequate environment for implant function and longevity over a moderate to long-term period.

Retrospective radiographic observational study of 1692 Straumann tissue-level dental implants over 10 years. II. Marginal bone stability.

Despite accumulating evidence for the longitudinal stability of the marginal bone level around an implant, there is limited evidence of predisposing risk factors for marginal bone loss based on some implants in a relatively large patient population. The aim of this study was to retrospectively determine the marginal bone loss around Straumann tissue-level dental implants during follow-up periods among which the maximum lasts up to 10 years, as well as the predisposing risk factors for peri-implant marginal bone loss. This study analyzed 1692 Straumann tissue-level dental implants in 881 patients, and relevant data were collected. The peri-implant marginal bone level was measured on periodic radiographs, and the changes in bone level were analyzed cumulatively from surgery until up to 10 years later. The log-rank test was used to select candidate critical risk factors for marginal bone loss, and multivariate analysis using Cox regression with the shared frailty model was performed. The overall peri-implant bone loss was 0.07 ± 0.21mm, 0.09 ± 0.26mm, 0.14 ± 0.41mm, and 0.17 ± 0.45mm at 3, 5, 7, and 9 years, respectively. Only 14 implants showed pathologic marginal bone loss exceeding 2mm during the follow-up period. While 2 implants were removed with continuous progressive marginal bone loss, 5 of the 14 implants showed early bone loss exceeding 1mm within the first year but then subsequently tended to show a stable marginal bone level. In the other seven implants, bone loss started after the first year and progressed continuously. Multivariate analysis revealed that diameter of the implant affected the peri-implant marginal bone loss. Straumann tissue-level dental implants showed only slight peri-implant marginal bone loss, with a very low incidence of pathologic marginal bone loss exceeding 2mm.

Bone loss at implants and teeth in thesame segment of the dentition in partially dentate subjects.

Some studies have indicated that marginal bone loss at implants and at teeth are similar, while results from other studies showed that implants lost more bone than teeth in the same dentition. To determine the amount of progressive marginal bone loss that had occurred at implants and teeth in the same segment of the dentition following implant placement in partially dentate subjects. A total of 217 patients with a total of 573 implants and 318 teeth present in the same segments of the dentition were included. Radiographs were available from 1year (baseline) and ≥3years after loading. The mean bone loss that occurred between the two examinations was at implants 0.42±0.68mm and at teeth 0.44±0.52mm. Thirty-eight subjects (18%) had ≥1 implant exhibiting >1mm bone loss. Bone loss at the 148 implants in this category of patients was 1.30±1.04mm with a corresponding loss at the 69 teeth of 0.53±0.62mm. Eighteen subjects (8%) had ≥1 tooth that exhibited >1mm bone loss. The mean amount of bone loss in this sample was 1.37±0.87mm (38 teeth) and 0.29±0.31mm (56 implants). This study showed that marginal bone loss at implants and teeth in many partially dentate subjects might be independent phenomena.

Original research radiological evaluation of marginal bone around dental implants: A pilot study

The use of dental implants has enabled the fabrication of highly functional and aesthetic restorations and improved the predictability of treatment. Standardized periapical radiographs at regular follow-up intervals are used to detect peri-fixtural radiolucency and/or progressive marginal bone loss or 'saucerization' around dental implants and thus to evaluate the success of implant. The aim of this study is to evaluate the early changes in the marginal bone level around dental implants through standard intraoral radiographs in the initial months of implant placement and to evaluate the relationship of various parameters i.e. gender, length and location of implants on amount of bone loss.

Single Lower Molar: Immediate vs. Delayed Loading. One Year Results of a Randomized Controlled, Prospective Split-Mouth Clinical Study

Statement of the Problem: There are not many studies available that are prospectively assessing, in a split mouth design, immediate loading of implants vs. the conventional approach. The aim of this study is to compare the outcome of immediate versus delayed implant loading, when replacing single lower molars bilaterally. Materials and Methods: This study was designed as a randomized, controlled, prospective, split-mouth clinical trial. Twenty patients, bilaterally missing first mandibular molars, were randomly assigned to be treated with an implant-supported prosthesis. A total of 40 implants (NobelReplace Tapered Groovy NobelBiocare) were bilaterally installed, replacing the inferior first molars. All the implants were inserted in native healthy bone with an insertion torque of 35/45 N.cm. One molar was restored with a non-occluding temporary crown within 24 h after implant placement, while the other side was restored after 3 months, according to a two-stage procedure. Final restorations with zirconia or metal-ceramic crowns were provided 6 months after implant placement. All implants were installed in healed sites. Follow-up checks were conducted at 3, 6 and 12 months after prosthetic loading. Methods of Data Analysis: The following outcome criteria were used: Implant success: The removal of implants was dictated by instability, progressive marginal bone loss, infection, or implant fracture. The stability of individual implants was measured at the time of definitive crown delivery (4–5 months after implant placement) by applying 35 Ncm of removal torque..Marginal bone loss: Periimplant marginal bone levels were evaluated on intraoral radiographs taken with the parallel technique at the time of implant placement and at 6 months and 1 year after definitive loading. Periimplant mucosal response: Probing pocket depth (PPD) and bleeding on probing (BOP) were measured with a periodontal probe at 6 months and 1 year after definitive crown delivery. Complications: Prosthetic complications, such as provisional or definitive crown fracture and abutment mobility or fracture, were evaluated. Statistical analyses were conducted using the JMP statistical software program (ver. 7.0; SAS Institute, Cary, NC, USA). Statistical significance was tested at the 0.05 probability level, and all values are presented as mean standard deviation. Results: Twenty patients were considered eligible and treated. No patient dropped out of the study within 1 year after definitive loading. No deviation from the protocol occurred. Assessments of procedure success are shown below. Implant success: All implants appeared stable at the time of definitive crown delivery. After 1 year of follow-up, the cumulative survival rate was 100% for delayed and immediately loaded implants. Marginal bone loss: Mean marginal bone loss was 0.83 0.1 mm in immediately loaded implants and 0.86 0.2 mm in two-stage delayed loading implants; no significant difference was found between groups at 6 and 12 months (p 0.05), Periimplant mucosal response: No significant difference (p 0.05) in PPD or BOP value was found between the two implant insertion methods Prosthetic complications: Two provisional acrylic crowns fractured 2 months after immediate loading. Two zirconiaceramic crowns had partial ceramic fractures. Conclusions: Within the limitations of this study the present findings seem to confirm that immediate loading of single lower molar implants restored with a nonoccluding temporary crown is a viable option comparable to the conventional two-stage delayed loading approach.

Implant failure: Etiology and complications

The possible occurrence of implant failure is a major concern for implantologists and knowledge in such unavoidable fact is clinically essential. Periimplantitis is an inflammatory response in which there is a loss of the bony support of the implant. Diagnosis is based on the clinical signs of infection such as hyperplastic soft tissues, suppuration, colour changes of the marginal peri-implant tissues and gradual bone loss. This site-specific infection may have many features in common with chronic adult periodontitis. Surgical trauma, micromotion and overload are also considered to be associated with implant failures. The lack of osseointegration is generally distinguished by implant mobility and radiological radiolucency. Here, the implant is considered to be failed . Progressive marginal bone loss without marked mobility is referring to a failing implant. The purpose of this concise review was to discuss the implant complications and failure by highlighting the major etiologic factors as well as the parameters used for evaluating such failure.

Subgingival Débridement Appears as Effective as More Complex and Expensive Therapies for Peri-Implantitis

Systematic review conclusion. Local antibiotics, bone augmentation and subgingival débridement all may be effective in treating peri-implantitis.Critical summary assessment. There is a need for properly designed studies to identify which treatments are most effective for peri-implantitis.Evidence quality rating. Limited. Systematic review conclusion. Local antibiotics, bone augmentation and subgingival débridement all may be effective in treating peri-implantitis. Critical summary assessment. There is a need for properly designed studies to identify which treatments are most effective for peri-implantitis. Evidence quality rating. Limited. What are the most effective treatments for peri-implantitis, the progressive marginal bone loss around dental implants induced by bacterial plaque infection? For this systematic review, the authors selected for inclusion randomized controlled trials (RCTs) involving patients with at least one stable implant demonstrating marginal bone loss who were treated for peri-implantitis. The authors included studies in which surgical and nonsurgical procedures aimed at treating peri-implantitis were evaluated. Outcome measures included change in probing pocket depth (PPD) and probing attachment level (PAL), as well as implant failure. The authors conducted an all-language search of several electronic databases (from as early as 1966 through January 2008) and relevant dental journals. They contacted selected authors and dental implant manufacturers to locate unpublished or ongoing RCTs. Two of the authors served as reviewers and independently duplicated the selection of studies for inclusion, evaluation of study quality, and data extraction. The authors identified seven studies (146 patients total) that met their inclusion criteria. In these studies, investigators evaluated the following treatments:use of topical antibiotic (metro-nidazole gel) versus ultrasonic débridement;manual débridement with and without use of topical antibiotic (10 percent doxycycline hyclate gel);different techniques of subgingival débridement;laser versus manual débridement with chlorhexidine (applied either via irrigation or in gel form);apical flap–repositioning surgery with and without implant polishing;augmentation with either nanocrystalline hydroxyapatite or bovine-derived xenograft and resorbable membrane. The only statistically significant differences between treatment outcomes were in two trials judged by the authors to be at high risk of bias. The addition of doxycycline to manual débridement provided an additional 0.6 millimeters&apos; improvement in PAL and PPD in patients demonstrating at least 50 percent bone loss. And although both augmentation procedures improved PAL and PPD, the bovine-derived xenograft/membrane group gained an additional 0.5 mm in PAL and PPD. The majority of studies in which more complex and expensive therapies for treating peri-implantitis were evaluated did not show statistically or clinically significant advantages for these treatments versus simple subgingival débridement. For treatments having similar degrees of effectiveness, there is no information on which have fewer adverse effects or are simpler or less expensive to use. The lack of reliable evidence demonstrating which treatments are most effective for treating peri-implantitis does not mean that treatments used are ineffective. Local antibiotics and bone augmentation may provide additional benefit in treatment of peri-implantitis, but large, well-designed RCTs are needed to address this question adequately.

Biomechanical consequences of progressive marginal bone loss around oral implants: a finite element stress analysis

The purpose of this study was to explore the biomechanical effects of progressive marginal bone loss in the peri-implant bone. Finite element model of a Ø 4.1 x 10 mm Straumann dental implant and a solid abutment was constructed as predefined eight-layers around the implant neck. The implant-abutment complex was embedded in a cylindrical bone model to analyze bone biomechanics regardless of anatomical influences. Angular and circular progressive marginal bone loss was simulated by sequential removal of each layer, resulting crater-like defects and a total of ten finite element models for analysis. Each model was subjected to a vertical and oblique static load of 100 N in separate load cases. Principal stress minimum and maximum, displacement, and equivalent of elastic strain outcomes were compared. Under vertical loading, principal stresses minimum and maximum decreased remarkably as with the increase in bone resorption. Under oblique load simulations, decrease in principal stress maximum and minimum was evident. With progressive bone loss and under oblique load simulations, displacement and equivalent of elastic strain increased considerably in trabecular bone contacting the implant neck. The presence of cortical bone contacting a load-carrying implant, even in a bone defect, improves the biomechanical performance of implants in comparison with only trabecular bone support as a sequel of progressive marginal bone loss.

Surface analysis of failed oral titanium implants.

The aim of the present study was to investigate the surface topography, composition, and oxide thickness of consecutively failed, oral Brånemark implants in order to determine possible causes for failure. The failure criterion was lack of osseointegration manifested as implant mobility. Ten implants were retrieved before loading (early failures) and 12 during a period of function up to 8 years (late failures). At retrieval, early losses did not display any clinical sign of infection. All late failures were radiographically characterized by peri-implant radiolucency and did not show infectious signs with one exception. No implant seemed to be lost due to peri-implantitis (plaque-induced progressive marginal bone loss). Twelve implants were analyzed by scanning electron microscopy (SEM), Auger electron spectroscopy (AES), and depth profiling using a blind protocol. Two pristine fixtures, which underwent the same preparation as the failed implants, were used as controls. In the SEM, control samples were essentially free from macroscopic contamination, whereas failed implants contained varying amounts of tissue residues. AES showed that all surfaces consisted of Ti oxide and varying amounts of additional elements, with C dominating in most cases. Nitrogen and sometimes Na, Ca, P, Cl, S, and Si were detected. The Si contamination was most likely due to ion leaching from the glass vials used for storage. Depth profiles showed a typical oxide thickness of 5-8 nm for all samples. In conclusion, no significant changes in the oxide layer composition or thickness as a result of implantation were observed. The results do not indicate any material-related cause for the failures of these implants. Possible reasons for these failures were impaired healing, asymptomatic infection, and overload.

Outcomes and their measurement in clinical trials of endosseous oral implants.

The clinical suitability of an oral implant system should be substantiated by well-planned clinical trials that meet the expectations of both the patient and the clinician; i.e., to offer anchorage to a dental prosthesis for one or more decades. The literature often reports on the survival rather than on the success rate, and for the latter a large variety of more or less stringent criteria have been proposed. Although the use of cumulative percentages to assess survival or success on consecutive patients, the so-called Kaplan-Meier statistics, is essential, many publications only report on absolute percentages, thus giving much too optimistic results. Indeed, the large number of recently inserted implants tend to dilute the small fraction that has gone through the maximum observation period. Multi-center studies on consecutive patients who are not selected on the basis of bone quality and volume should be recommended. Otherwise the labeling of the implant should clearly mention which groups; e.g., smokers or patients with limited bone volume are not part of the validated target group. The final outcome measurement would be that an endosseous implant is no longer able to carry out its purpose: to anchor or support successfully a functional dental prosthesis. Like many other clinical evaluations, surrogate parameters have been sought to assess interim success rates. The stability of the marginal bone level is one parameter proposed by many, although bone loss as such is not synonymous with failure. Several implant systems with a roughened surface (plasma sprayed or coated) suffer from progressive marginal bone loss and consequently ongoing loss of implants even after 5 or more years. Those implant systems should be evaluated with cumulative success rates over a period of 10 years. Only those that demonstrated a clustering of both bone and implant loss during the first 1 or 2 years after insertion and subsequently a levelling off for those two parameters-a so-called plateau pattern, should be allowed to draw conclusions after 5 years. Since radiographs reveal only the approximal areas, measurement of the attachment level by means of probing towards a reference point on the abutment should also be performed annually. Intra-oral radiographs can only reveal absence of radiolucency at the bone-implant interface, but do not prove osseointegration. The use of an electronic device offers objective results and reveals even subclinical mobilities of endosseous implants. One can conclude that there is an urgent need for a consensus between health authorities, third parties, and the scientific community to define a set of universally-acceptable success criteria, to impose the use of cumulative success rates, and to ask for observation periods of 10 years for implants that do not demonstrate stable results after one or two years.

Reproducibility and Detection Threshold of Peri-Implant Diagnostics

There is an increasing awareness that, for clinical monitoring of oral implants, there is a need for reliable diagnostics and possibly prognostic parameters. Indeed, reports have too often limited results to an inventory of failures, while no mention was made of progressive marginal bone loss or other symptoms of a future failure. Several parameters, such as marginal bone level assessment and/or probing attachment level, give a precision of up to 0.5 mm. Both measurements also seem related. The damping characteristics of the individual implant/bone unit also offer a highly reproducible diagnostic tool. The Periotest allows for detection of subclinical mobilities, and 95% of repeated measurements fall within a range of one unit on the arbitrary scale. So far, these three parameters offer no prognostic value.