Could Future Implant Failures be Predicted Based on Observed Bone Levels and Bone Loss After 5 Years? A Retrospective Investigation on Patients Presented in Previous Studies.

Purpose: To evaluate the diagnostic accuracy of bone loss/bone levels, as detected after 5 years of implant function, in identifying patients who suffered implant failures in the following 5 years. Materials and Methods: Data on radiographic measurements of marginal bone levels at prosthesis placement and after 5 years of function were retrospectively retrieved from 11 previous publications. Included patients were allocated into different subgroups with regard to bone loss/bone level during/after 5 years in function, respectively. A diagnostic test was used to estimate the accuracy of finding patients/jaws/implants at risk for a future implant failure by calculating sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) in different subgroups, respectively. Results: Altogether, 749 treated jaws (723 patients/3,363 implants) were included in the study group. Treated jaws in the high-level subgroups presented an overall higher risk of implant failures from 5 to 10 years in function (P < .05). Many treated jaws/implants were allocated into the high-level groups, but the proportions of implant failures were low in these groups. The diagnostic test comparing high- and low-level groups with and without implant failures showed low accuracy to predict implant failures; the PPV ranged from 4% to 33%. Lower PPVs were observed for diagnostic tests for individual implants (range: 4% to 6%). Conclusion: More severe bone loss was associated with higher risk of future implant failure. However, many patients/ implants with obvious bone loss in the study group and low prevalence of implant failures at the 10-year examination resulted in poor accuracy in identifying individual patients or implants at risk for failure. This suggests that it is difficult to predict future implant failures based only on radiographic measurements.

Implications of considering peri-implant bone loss a disease, a narrative review.

BACKGROUND: Peri-implantitis has been suggested to cause significant increasing proportions of implant failure with increasing time. PURPOSE: To assess whether implant failure rates in long term studies are matching the supposed high prevalence of peri-implantitis. MATERIAL AND METHODS: This paper is written as a narrative review of the long-term clinical investigations available in the literature. RESULTS: Some implant systems have seen unacceptable marginal bone loss figures with time coupled to increased implant failure rates, resulting in the withdrawal of these systems. The reasons for such mishap are generally unknown, with the exception of one system failure that was found to be due to improper clinical handling. Modern, moderately rough implant systems have functioned excellently over 10-15 years of follow up with minor problems with marginal bone loss and implant failure rates within a few per cent. Machined implants have functioned adequately over 20-30 years of follow up. Implant failures occur predominantly during the first few years after implant placement. No significant increase of implant failures has been observed thereafter over 20-30 years of follow up. Over the years of our new millennium, scientific and technical advances have allowed the discovery of numerous molecular pathways and cellular interactions between the skeletal and immune system promoting the development of the interdisciplinary field called osteoimmunology. Nowadays, this knowledge has not only allowed the emergence of new etiologic paradigms for bone disease but also a new dynamic approach on the concept of osseointegration and MBL around oral implants, re-evaluating our older disease oriented outlook. This facilitates at the same time the emergence of translational applications with immunological perspectives, scientific approaches based on omics sciences, and the beginning of an era of personalized dental implant therapy to improve the prognosis of oral implant treatment. CONCLUSIONS: Oral implant systems have been found to function with very good clinical outcome over follow-up times of 20-30 years. Registered implant failures have occurred predominantly during the first few years after implantation, and there has been no significant increase in late failures due to peri-implantitis.

On marginal bone level changes around dental implants.

BACKGROUND: Peri-implant bone level values have been used as the clinical standard of reference to describe the status of a dental implant, despite the fact that their significance for the long-term survival of the implant has never been properly assessed. PURPOSE: To challenge the assumption that the natural course of peri-implant bone loss is the loss of the implant. MATERIALS AND METHODS: This article is a narrative review on reasons and interpretations of marginal bone level changes around dental implants. RESULTS AND CONCLUSIONS: Different views regarding the pattern and progression of marginal bone loss depending on dental specialties have been identified. However, the present finding of a negative correlation between an increasing cumulative marginal bone loss and a decreasing risk of implant failures over time indicates that peri-implant marginal bone loss does not necessarily represent a condition of disease. Reduction of marginal bone levels may be observed in a majority of patients during follow-up time, with only a minority of those patients losing implants and implant-supported prostheses in the long term. Bone level changes seem often to occur as a consequence of physiological processes and/or as an adaptation to altered external as well as host response factors. Periodical radiological assessments of implant-restorations remain a valid diagnostic tool for the detection of potential implant fractures, loss of osseointegration, screws working loose and for the detection of the few cases with advanced, continuously progressing marginal bone loss during time. The detection of peri-implant marginal bone loss at one time point should not be immediately considered as a sign of ongoing pathology and of an increased risk of future loss of the implant in question.

Are marginal bone level changes around dental implants due to infection?

BACKGROUND: Peri-implant bone level values have been used as the clinical standard of reference to describe the status of a dental implant. Reduction of marginal bone levels in association with bleeding on probing have been claimed to be a sign of pathology and an indication of treatment needs. PURPOSE: To assess the available evidence that peri-implant bone loss is caused by infection. MATERIALS AND METHODS: This article is a narrative review on the interpretation of marginal bone level changes around dental implants as a consequence of infection. RESULTS AND CONCLUSIONS: There is evidence that plaque accumulation induces an inflammatory reaction in the peri-implant soft tissues and that resumption of plaque control measures results in the reduction of the inflammation. Since plaque is always present in the oral cavity, a cause-effect relationship between plaque accumulation and peri-implantitis, defined as inflammation of the peri-implant soft tissues associated with marginal bone loss has been difficult to validate and has not been proven so far. There is no evidence of the mechanisms involved in the tissue reactions resulting in the conversion from a state of an inevitable inflammation contained in the soft tissues to a state of inflammation involving the loss of peri-implant marginal bone. There is today no consensus whether implants should be expected to be surrounded by tissues which are completely free from inflammation, or that an "immune-driven", chronic, subclinical inflammation should be expected at the foreign body implant. The infectious origin theory appears to be mainly supported by ligature-induced experimental peri-implantitis investigations in animal models that suffer of several methodological problems, and therefore, provide misleading information with regards to human clinical applications in large, routine populations.

Is Peri-Implant Probing Causing Over-Diagnosis and Over-Treatment of Dental Implants?

Pocket probing depth (PPD) and bleeding on probing (BOP) measurements are useful indices for the assessment of periodontal conditions. The same periodontal indices are commonly recommended to evaluate the dental implant/tissue interface to identify sites with mucositis and peri-implantitis, which, if not treated, are anticipated to lead to implant failure. The aim of the present narrative review is to discuss the available literature on the effectiveness of probing at dental implants for identification of peri-implant pathology. There is substantial clinical evidence that PPD and BOP measurements are very poor indices of peri-implant tissue conditions and are questionable surrogate endpoints for implant failure. On the contrary, the literature suggests that frequent disturbance of the soft tissue barrier at implants may instead induce inflammation and bone resorption. Moreover, over-diagnosis and subsequent unnecessary treatment may lead to iatrogenic damage to the implant-tissue interface. Despite this, the recommendations from recent consensus meetings are still promoting the use of probing at dental implants. For evaluation of implants, for instance at annual check-ups, the present authors recommend a clinical examination that includes (i) a visual inspection of the peri-implant tissues for the assessment of oral hygiene and the detection of potential redness, swelling, (ii) palpation of the peri-implant tissues for assessment of the potential presence of swelling, bleeding, suppuration. In addition, (iii) radiography is recommended for the assessment of crestal bone level for comparison with previous radiographs to evaluate potential progressive bone loss even if there is a need for more scientific evidence of the true value of the first two clinical testing modes.

Bone loss around oral and orthopedic implants: An immunologically based condition.

BACKGROUND: Marginal bone resorption has by some been identified as a "disease" whereas in reality it generally represents a condition. PURPOSE: The present article is a comparison between oral and orthopedic implants, as previously preferred comparisons between oral implants and teeth seem meaningless. MATERIALS AND METHODS: The article is a narrative review on reasons for marginal bone loss. RESULTS AND CONCLUSIONS: The pathology of an oral implant is as little related to a tooth as is pathology of a hip arthroplasty to a normally functioning, pristine hip joint. Oral as well as orthopedic implants are recognized as foreign bodies by the immune system and bone is formed, either in contact or distance osteogenesis, to shield off the foreign materials from remaining tissues. A mild immune reaction coupled to a chronic state of inflammation around the implant serve to protect implants from bacterial attacks. Having said this, an overreaction of the immune system may lead to clinical problems. Marginal bone loss around oral and orthopedic implants is generally not dependent on disease, but represents an immunologically driven rejection mechanism that, if continuous, will threaten implant survival. The immune system may be activated by various combined patient and clinical factors or, if rarely, by microbes. However, the great majority of cases with marginal bone loss represents a temporary immune overreaction only and will not lead to implant failure due to various defense mechanisms.

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.

Precision of a CAD/CAM technique for the production of zirconium dioxide copings.

PURPOSE: The precision of a computer-aided design/manufacturing (CAD/CAM) system to manufacture zirconium dioxide copings with a predetermined internal space was investigated. MATERIALS AND METHODS: Two master models were produced in acrylic resin. One was directly scanned by the Decim Reader. The Decim Producer then manufactured 10 copings from prefabricated zirconium dioxide blocks. Five copings were prepared, aiming for an internal space to the master of 45 microm. The other five copings were prepared for an internal space of 90 microm. The second test model was used to try in the copings produced. The obtained internal space of the ceramic copings was evaluated by separate measurements of the master models and inner surfaces of the copings. The master models were measured at predetermined points with an optical instrument. The zirconium dioxide copings were measured with a contact instrument at the corresponding sites measured in the masters. RESULTS: The first group of copings had a mean internal space to the scanned master of 41 microm and of 53 microm to the try-in master. In general, the internal space along the axial walls of the masters was smaller than that along the occlusal walls. The second group had a mean internal space of 82 microm to the scanned master and of 90 microm to the try-in master. CONCLUSION: The aimed-for internal space of the copings was achieved by the manufacturer. The CAD/CAM technique tested provided high precision in the manufacture of zirconium dioxide copings.

Fit of a new pressure-sintered zirconium dioxide coping.

PURPOSE: The aim of this study was to determine in vitro the internal and marginal fit of zirconium dioxide ceramic copings manufactured using a recently introduced CAD/CAM-based technique (Denzir). MATERIALS AND METHODS: Two master models were produced in metal, representing the maxillary right central incisor and first premolar. Two A-silicone impressions were used for each of the master models, and from each of the impressions five stone dies with the corresponding ceramic copings were produced, for a total of 20 copings. The A-silicone replica of the misfit of the ceramic coping to the corresponding stone die and master model was sectioned buccolingually and mesiodistally. The obtained sections were measured at occlusal, axial, and marginal locations under light microscopy. Twenty-four measurements for each replica were made. The Student's t test was used to detect significant differences between coping-stone die and coping-master model misfits. RESULTS: For any combination, the marginal fit was superior to the axial and occlusal fit. In general, the misfit between the coping and the stone die did not differ significantly from the misfit detected between the coping and the master model. However, a better fit was recorded for the first premolar at the occlusal portion in the coping-stone die combination compared to the coping-master model combination. The mean marginal discrepancy between the copings and master models was clearly below 50 microm, with a range of 0 to 115 microm. CONCLUSION: The accuracy achieved by the Denzir manufacturing process for the production of zirconium dioxide copings is well within the range of clinical acceptability.

The effect of a dentifrice in the prevention of recurrent aphthous stomatitis.

PURPOSE: A multicenter, double-blind, randomized, placebo-controlled clinical trial was conducted to determine the efficacy of an experimental dentifrice on the prevention of recurrent aphthous stomatitis (RAS). MATERIAL AND METHODS: A 3-month pretrial period was used to self-record data pertaining to the frequency, ulcer size, duration, and pain associated with ulcers. Thirty-six participants, who reported at least 3 RAS episodes or 30 days with RAS during the pretrial period, completed the study. Following a stratified randomization for age, sex and disease severity, the participants received the experimental dentifrice (T) or the placebo (C). The test period comprised 3 months of self-evaluation of number of ulcers, size and location. Pain related to RAS was estimated by the use of a Visual Analogue Scale (VAS). RESULTS: Symptoms were found to decrease in both groups when the pretrial and test periods were compared, although no statistical difference was reached in the C group. A statistically significant difference between the two time periods was obtained for the T group concerning the number of days with ulcers (p < 0.025) and VAS (p < 0.010). Of more clinical importance was the observation that 50% of the patients in the T group reported a more than 50% reduction in days with ulcers compared to 17% in the C group. CONCLUSIONS: The dentifrice may be used as a treatment strategy for a subgroup of patients with RAS in view of the low adverse effects and the benefit of using a treatment modality that is a part of daily routines.