Influence of diameter and length on primary stability in various implant site densities-An in vitro study in polyurethane blocks.

BACKGROUND: The influence of dental implant length and diameter on primary stability in various bone densities is not well understood. AIM: To in vitro study the effect of length and diameter on resonance frequency analysis (RFA), insertion torque (IT) and displacement (DP) measurements of dental implants in different implant site densities. MATERIALS AND METHODS: Dental implants of four different diameters (Ø 3.5, 4.0, 4.5 and 5.0 mm) and three different lengths (7, 11 and 15 mm) (Neoss Ltd, Harrogate, UK) were placed in polyurethane blocks of three different densities (Sawbones Europe AB, Malmö, Sweden). The primary stability was assessed by RFA (ISQ) (Osstell, Osstell AB, Gothenburg, Sweden) and insertion torque measurements (ITmax in N cm) (iChiropo™, Bien-Air Dental SA, Bienne, Switzerland). In addition, the blocks were mounted in a rig and a lateral force of 25 N cm was applied to the implants and the DP was measured in µm with a micrometer gauge placed on the opposite side of the load transducer. Statistical analyses using linear and quadratic models were applied. RESULTS: Implant length, diameter and block density were found to be significant independent predictors of RFA, ITmax, and DP measurements. Implant length had a strong effect, while the effect of diameter in general was subtle, particularly in the softest block. CONCLUSIONS: Implant length affects primary stability more than implant diameter in polyurethane blocks of uniform density along the whole length of the tested implants.

Osteotome-Induced Blood Clot and Subsequent Bone Formation with the Use of Collagen Sponge for Integration of Single Dental Implants into the Atrophied Posterior Maxilla: A Retrospective Follow-Up of 36 Implants after 5 to 13 years.

BACKGROUND: Atrophy of the posterior maxilla as a consequence of tooth loss and sinus pneumatization is a frequent condition encountered in the clinical practice. Prosthetic rehabilitation with implants in these patients often requires some kind of bone regeneration procedure to increase the bone volume. AIM: The aim of the present retrospective study is to analyze the survival and success rates of a series of implants placed in the atrophic posterior maxilla with a transcrestal osteotome procedure, without placing a bone grafting material. MATERIALS AND METHODS: From 2006 to 2014, 36 dental implants (Neoss Ltd., Harrogate, UK) were inserted in 36 patients with at least 4 mm of bone below the maxillary sinus using transcrestal osteotome sinus floor elevation and placement of collagen sponge below the sinus membrane. ISQ measurements were made after implant placement and at abutment surgery after 4 to 6 months. The vertical bone height (VBH) was evaluated in intraoral radiographs taken prior to surgery and in radiographs from annual check-up appointments 5 to 13 years after implant placement. In addition, marginal bone loss (MBL) was evaluated. RESULTS: One implant was lost after four years of prosthetic loading. The remaining 35 implants showed no complications and were loaded with single crowns after 4-6 months of healing. All 35 implants showed clinical success after 8.5 ± 2.8 years of prosthetic loading (from 5 to 13 years). The vertical bone height was 5.9 ± 1.4 mm at surgery, 9.7 ± 1.1 mm at second surgery after 4-6 months, and 8.3 ± 1.8 at the follow-up at 8.5 ± 2.8 years (from 5 to 13 years). The implant stability registered was 73.2 ± 6.2 ISQ at the surgery and 75.8 ± 3.9 at the second surgery after 4-6 months. CONCLUSIONS: The present long-term follow-up study showed that the crestal approach for sinus floor bone augmentation without additional bone grafting results in predicable bone formation and high implant survival. The osteotome technique is a valid alternative to the more invasive lateral window technique in single cases with a minimum of 4 mm of VBH below the maxillary sinus.

Piezoelectric bone surgery compared with conventional rotary instruments in oral surgery and implantology: Summary and consensus statements of the International Piezoelectric Surgery Academy Consensus Conference 2019.

PURPOSE: Piezoelectric bone surgery was introduced into clinical practice almost 20 years ago as an alternative method for cutting bone in dental surgical procedures, in an attempt to reduce the disadvantages of using conventional rotary instruments. The aim of this Consensus Conference was to evaluate the current evidence concerning the use of piezoelectric surgery in oral surgery and implantology. MATERIALS AND METHODS: Three working groups conducted three meta-analyses with trial sequential analysis, focusing on the use of piezoelectric surgery in impacted mandibular third molar extraction, lateral sinus floor elevation and implant site preparation. The method of preparation of the systematic reviews, based on comprehensive search strategies and following preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines, was discussed and standardised. RESULTS: Moderate/low evidence suggests that piezoelectric surgery is significantly associated with a more favourable postoperative course (less pain, less trismus) after impacted mandibular third molar extraction than conventional rotary instruments. Moderate evidence suggests that implants inserted with piezoelectric surgery showed improved secondary stability during the early phases of healing compared with those inserted using a drilling technique. Strong/moderate evidence suggests that piezoelectric surgery prolongs the duration of surgery in impacted mandibular third molar extraction, sinus floor elevation and implant site preparation, but it is unclear whether the slight differences in duration of surgery, even if statistically significant, represent a real clinical advantage for either operator or patient. Weak evidence or insufficient data are present to draw definitive conclusions on the other investigated outcomes. CONCLUSIONS: Further well-designed trials are needed to fully evaluate the effects of piezoelectric surgery, especially in implant site preparation and sinus floor elevation.

Piezoelectric bone surgery for implant site preparation compared with conventional drilling techniques: A systematic review, meta-analysis and trial sequential analysis.

PURPOSE: To evaluate whether the use of piezoelectric bone surgery (PBS) for implant site preparation reduces surgical time, improves implant stability, preserves marginal bone level and improves the survival rate of oral implants compared with conventional drilling techniques. MATERIALS AND METHODS: This meta-analysis followed the PRISMA (preferred reporting items for systematic review and meta-analysis) guidelines and was registered in the PROSPERO (international prospective register of systematic reviews) database (CRD42019142749). The PubMed, Embase, Scopus and Open Grey databases were screened for articles published from 1 January 1990 to 31 December 2018. The selection criteria included randomised controlled trials (RCTs) and case-control studies (CCTs) comparing the PBS with conventional rotary instruments for implant site preparation, and reporting any of the selected clinical outcomes (surgical time, implant stability, marginal bone variations and implant failure rate) for both groups. The risk of bias assessment was performed using the Cochrane Collaboration tool for RCTs and the Newcastle-Ottawa scale (NOS) for CCTs. A meta-analysis was performed, and the power of the meta-analytic findings was assessed by trial sequential analysis (TSA). RESULTS: Eight RCTs and one CCT met the inclusion criteria and were included in the review. The meta-analysis and the TSA showed moderate evidence suggesting that the PBS prolongs surgery duration and improves secondary stability 12 weeks after implant placement compared with conventional drilling techniques. Insufficient data are available in literature to assess if the PBS reduces marginal bone loss and/or improves the implant survival rate compared with conventional drilling techniques. CONCLUSIONS: Adequately powered randomised clinical trials are needed to confirm the PBS positive effect on the secondary stability and to draw conclusions about the influence of PBS on marginal bone stability and implant survival.

Factors influencing marginal bone loss at a hydrophilic implant design placed with or without GBR procedures: A 5-year retrospective study.

BACKGROUND: Ongoing marginal bone loss is a threat to the longevity of implant-supported prostheses. AIM: The aim of the present study was to retrospectively evaluate the survival rate and factors affecting marginal bone levels at a hydrophilic implant design after 5 years in function. MATERIALS AND METHODS: The study group consisted of 51 consecutive patients previously treated with 159 hydrophilic implants (Neoss Straight Proactive implants) and scheduled for annual check-ups with clinical and radiographic examinations during 5 years. Data were compiled for the entire study population as well as for two subgroups: one where guided bone regeneration (GBR) was performed (91 implants) and the other where no GBR procedures (68 implants) were performed. Marginal bone levels were measured from peri-apical radiographs taken at placement and annual follow-ups. Statistical analyses were applied to evaluate the effect of different factors on marginal bone remodeling. RESULTS: Two implant failures, one from each subgroup, occurred during the first year of function resulting in an overall cumulative survival rate (CSR) of 98.7% after 5 years of loading. The mean marginal bone loss amounted to 0.7 ± 0.7 mm after 1 year and 0.8 ± 0.6 mm after 5 years. No implants showed more than 3 mm bone loss after 5 years. Age, gender, implant position, biotype, implant diameter, implant length, indication, surgical/loading protocol, and ISQ at prosthesis delivery were found to affect bone remodeling. No significant differences or correlations were seen for smoking, jaw, bone quantity, bone quality, GBR, sinus lift, and ISQ at implant placement. CONCLUSIONS: The present implant design performed well with few failures and minimal marginal bone loss after 5 years of loading. Marginal bone remodeling at implants is a complex phenomenon, which is affected by many patient-, procedure-, and implant-related factors that need to be further investigated.

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.

Factors Influencing Resonance Frequency Analysis (RFA) Measurements and 5-Year Survival of Neoss Dental Implants.

BACKGROUND: Diagnostic instruments based on resonance frequency analysis (RFA) can be utilised to assess dental implant stability during treatment and follow-up. AIM: The aim of the present study was to investigate the influence of patient- and implant-related factors on implant stability and the 5-year implant survival. In addition, the influence of stability (ISQ value) at placement and abutment connection on implant survival was evaluated. MATERIALS AND METHODS: RFA measurements from a total of 334 consecutive patients with 745 dental implants (Neoss Ltd., Harrogate, UK) were retrospectively analysed after at least 5 years in function. Statistics were used to evaluate the influence of the different variables on implant stability and implant survival. Odds ratio calculations were performed to compare the risk for implant failure using 60, 65, 70, and 75 ISQ as threshold levels at placement and loading. RESULTS: A total of 20 implant failures in 14 patients were noted during the 5 years of follow-up, giving an overall cumulative survival rate (CSR) of 97.3% at the implant level and 95.8% at the patient level. Gender, jaw, position, bone quality, and implant diameter had an influence on implant stability at placement. Jaw, bone quality, and implant diameter had an influence on stability after 3-4 months of healing. More failures were observed in full than in partial rehabilitations. Age, gender, jaw, position, bone quantity, bone quality, implant diameter, and implant length had no influence on implant survival. Implants with ISQ values below the threshold levels showed lower survival rates compared to implants with values above these levels. CONCLUSIONS: The present study showed a significantly higher risk for implant failure, showing an ISQ value below 70 and 75 at placement or after 3-4 months of healing. The results indicate that RFA measurements can be used to identify implants with increased risk for failure.

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.

Sinus floor elevation procedures to enable implant placement and integration: techniques, biological aspects and clinical outcomes.

Implant treatment in an atrophied edentulous posterior maxilla constitutes a challenge for the therapeutic team. The authors of the present study acknowledge that modern micro-rough surface implants in lengths of about 8-10 mm or longer and of different brands are similarly successful. Consequently, the authors propose that the use of different sinus floor elevation techniques should be considered when < 8 mm of bone is available below the maxillary sinus. The type of sinus floor elevation technique selected is mainly based on residual vertical bone height, marginal bone width, local intrasinus anatomy and the number of teeth to be replaced, although other factors (such as surgical training and surgical experience) may have an impact. It is proposed that a transcrestal sinus floor elevation approach can be considered as a first-choice method for single tooth gaps in situations with sufficient width for implant placement and a residual bone height of 5-8 mm, while lateral sinus floor elevation, with or without grafting materials, is indicated when < 5 mm of bone is available and when several teeth are to be replaced. With regard to time of implant placement, a one-stage procedure is preferred provided that high primary stability can be ensured.

Initial and long-term crestal bone responses to modern dental implants.

Successful osseointegration is the result of a controlled foreign body reaction to dental implants. Osseointegrated implants have demonstrated excellent long-term survivability, although they may be subject to limited marginal bone loss. Marginal bone loss during the first few years after implant placement seldom represents disease, but is instead the result of an adaptive bone response to surgical trauma and implant loading. It is not uncommon for implants with early marginal bone loss to enter a long-lasting state of bone stability. Extensive bone resorption after the first year is generally due to an exacerbation of adverse body reactions caused by non-optimal implant components, adverse surgery or prosthodontics and/or compromised patient factors. Disease in the form of peri-implantitis is a late complication that affects some implants with suppuration and rapid loss of crestal bone, and is probably caused by bacterial pathogens and immunological reactions. Unfortunately, the literature is not consistent with respect to the type or magnitude of clinical implant problems, including how they are defined and diagnosed. If the peri-implantitis diagnosis is confined to cases with infection, suppuration and significant bone loss, the frequency of the disease is relatively low, which is in sharp contrast to the frequencies reported with unrealistic definitions of peri-implantitis. We suggest that when modern implants are placed by properly trained individuals, only 1-2% of implants show true peri-implantitis during follow-up periods of 10 years or more. Peri-implantitis must be separated from the initial and self-limiting marginal bone loss.

Modern implant dentistry based on osseointegration: 50 years of progress, current trends and open questions.

In the 1960s and 1970s, implant-supported prostheses based on subperiosteal or blade implants had a poor reputation because of questionable clinical outcomes and lack of scientific documentation. The change to a scientifically sound discipline was initiated by the two scientific pioneers of modern implant dentistry, Professor P. I. Brånemark from the University of Gothenburg in Sweden and Professor André Schroeder from the University of Bern in Switzerland. Together with their teams, and independently of each other, they laid the foundation for the most significant development and paradigm shift in dental medicine. The present volume of Periodontology 2000 celebrates 50 years of osseointegration. It reviews the progress of implant therapy over the past 50 years, including the basics of implant surgery required to achieve osseointegration on a predictable basis and evolving innovations. The development of bone-augmentation techniques, such as guided bone regeneration and sinus floor elevation, to correct local bone defects at potential implant sites has increased the indications for implant therapy. The paradigm shift to moderately rough implant surfaces resulted in faster and enhanced bone integration and led to improvements in various treatment protocols, such as immediate and early implant placement in postextraction sites, and made various loading protocols possible, including immediate and early implant loading. In the past 15 years, preoperative analysis and presurgical planning improved as a result of the introduction of three-dimensional imaging techniques. Hereby, cone-beam computed tomography offers better image quality with reduced radiation exposure, when compared with dental computed tomography. This opened the door for digital planning and surgical modifications. Over the last 50 years this evolution has facilitated tremendous progress in esthetic outcomes with implant-supported prostheses and improved patient-centered outcomes. This volume of Periodontology 2000 also discusses the current trends and open questions of implant dentistry, such as the potential of digital implant dentistry in the surgical and prosthetic field, the trend for an increasing average age of implant patients and the related adaptations of treatment protocols, and the second attempt to establish ceramic implants using, this time, zirconia as the implant material. Finally, some of the hottest controversies are discussed, such as recent suggestions on bone integration being a potential foreign-body reaction and the evidence-based appraisal of the peri-implantitis debate.

A Randomized Case-Series Study Comparing the Stability of Implant with Two Different Surfaces Placed in Fresh Extraction Sockets and Immediately Loaded.

Background. Hydrophilic and moderately rough implant surfaces have been proposed to enhance the osseointegration response. Aim. The aim of this study was to compare early changes of stability for two implants with identical macrodesign but with different surface topographies. Materials and Methods. In 11 patients, a total of 22 implants (11 bimodal (minimally rough, control) and 11 proactive (moderately rough and hydrophilic, test), Neoss Ltd., Harrogate, UK) were immediately placed into fresh extraction sockets and immediately loaded. The peak insertion torque (IT) was measured in Ncm at placement. Resonance Frequency Analysis (RFA) measurements were made at baseline and 2, 4, 6, and 12 weeks after surgery. Results. The two implant types showed similar IT and RFA values at placement (NS). A dip of RFA values after 2 weeks followed by an increase was observed, where the test implant showed a less pronounced decrease and a more rapid recovery than the control implant. The test implants were significantly more stable than the control ones after 12 weeks. Conclusions. The results from the present study indicated that the hydrophilic and rougher test implant was more resistant to immediate loading and showed a significantly higher stability than the smoother control implant after 12 weeks.

A One-year Follow-up Study of a Tapered Hydrophilic Implant Design Using Various Placement Protocols in the Maxilla.

PURPOSE: To study the clinical/radiographic outcomes and stability of a tapered implant design with a hydrophilic surface when placed in the maxilla using various protocols and followed for one year. METHODS: Ninety-seven consecutive patients treated as part of daily routine in two clinics with 163 tapered implants in healed sites, in extraction sockets and together with bone augmentation procedures in the maxilla were evaluated after one year in function. Individual healing periods varying from 0 to 6 months had been used. Insertion torque (IT) and resonance frequency analysis (RFA) measurements were made at baseline. Follow-up RFA registrations were made after 6 and 12 months of loading. The marginal bone levels were measured in intraoral radiographs from baseline and after 12 months. A reference group consisting of 163 consecutive straight maxillary implants was used for the comparison of baseline IT and RFA measurements. RESULTS: Five implants failed before loading, giving an implant survival rate of 96.9% and a prosthesis survival rate of 99.4% after one year. The mean marginal bone loss after one year was 0.5 mm (SD 0.4). The mean IT was statistically significantly higher for tapered than for straight reference implants (41.3 ± 12.0 Ncm vs 33.6 ± 12.5 Ncm, p < 0.001). The tapered implants showed a statistically insignificantly higher mean ISQ value than the straight references implants (73.7 ± 6.4 ISQ vs 72.2 ± 8.0 ISQ, p=0.119). There was no correlation between IT and marginal bone loss. There was a correlation between IT and RFA measurements (p < 0.001). CONCLUSION: The tapered implant showed a high survival rate and minimal marginal bone loss after one year in function when using various protocols for placement. The tapered implant showed significantly higher insertion torque values than straight reference implants.

A 1-Year Clinical and Radiographic Study on Hydrophilic Dental Implants Placed with and without Bone Augmentation Procedures.

PURPOSE: The aim of the present 1-year clinical and radiographic study was to evaluate a hydrophilic dental implant when used in everyday cases in one clinic. The purpose was also to compare augmented with nonaugmented sites. MATERIALS AND METHODS: The study group consisted of 50 consecutive patients treated with 159 dental implants (Proactive, Neoss Ltd, Harrogate, UK) in both mandibles and maxillae. Ninety-two implants were placed with adjunct bone augmentation procedures, whereas 40 implants were placed in augmented maxillary sinus sites. A two-stage procedure was used for 84 implants and a one-stage procedure for 47 implants. Twenty-eight implants were immediately loaded. Implant stability was measured with resonance frequency analysis (RFA) at placement and at prosthesis delivery. The patients were scheduled for checkups after 6 and 12 months in function with clinical and radiographic examinations. Marginal bone level measurements were performed in baseline and follow-up intraoral radiographs. RESULTS: Two implant failures in two patients were experienced after 1 year of loading, giving a survival rate of 98.7%. One implant in nonaugmented sites and one implant in conjunction with an augmentation procedure (sinus lift), giving a survival rate of 98.5% and 98.9% for healed and augmented sites, respectively (NS). RFA measurements showed 70.2 ± 9.5 ISQ at placement and 76.5 ± 5.9 ISQ (p ≤ 0.001) after a mean healing time of 5.6 ± 1.6 months. The marginal bone loss amounted to 0.7 ± 0.7 mm after 1 year of loading. Frequency distribution showed bone gain or less than 1 mm bone loss for the majority of implants (69.3%), whereas 25.7% showed 1.1 to 2 mm, 5.0% more than 2 mm and no implants more than 3 mm of bone loss. CONCLUSIONS: The use of Neoss Proactive implants for prosthetic rehabilitation of consecutive patients resulted in predictable clinical and radiographic outcomes after 1 year of loading with no differences between augmented and nonaugmented sites.

Two different implant designs and impact of related drilling protocols on primary stability in different bone densities: an in vitro comparison study.

PURPOSE: To conduct an in vitro comparison study on the primary stability of two different clinically used dental implant designs. MATERIALS AND METHODS: Eighteen pairs of osteotomies were prepared in fresh bovine bone specimens. The control implant had a subtle tapering and was placed using straight drills. The test implant had a marked tapering and was placed using tapered drills. The bone density at the experimental sites was determined in Hounsfield units (HUs) by using cone beam computed tomography and imaging software. The implants were inserted during continuous registration of insertion torque. The bone blocks were embedded in plaster for firm fixation in a rig for displacement measurements. Resonance frequency analysis (RFA) measurements were taken. A lateral force of 15 N was applied to the RFA transducer and the displacement measured in micrometers. A flex constant (µm/N) was calculated for each measurement. RESULTS: The test implants displayed statistically significantly higher primary stability than the control implants for all parameters. There was a marked difference in displacement and flex constant in low-density bone in favor of the test implant, but there was no obvious difference in higher-density bone. CONCLUSION: In this study, placement of a tapered implant design using tapered drills resulted in higher primary stability than a control implant with subtle tapering using straight drills. The results indicate that the novel implant may work particularly well in soft bone densities such as the posterior maxilla. However, clinical studies are needed to confirm this.

On the Early Mechanisms of Bone Formation after Maxillary Sinus Membrane Elevation: An Experimental Histological and Immunohistochemical Study.

BACKGROUND: Previous studies have shown predictable bone formation in the maxillary sinus after membrane elevation. However, how and where the bone is formed is not well understood. PURPOSE: The aim of the study was to histologically and immunohistochemically study the early bone formation events in primates after membrane elevation in the maxillary sinus. MATERIALS AND METHODS: Nine adult male tufted capuchin primates (Cebus apella) were included in the study. Eight animals were subjected to bilateral maxillary sinus membrane elevation using a lateral replaceable bone window technique. One oxidized dental implant was placed into the maxillary sinus cavity on both sides. In four animals, one sinus was left without any additional treatment, whereas the contralateral sinus was filled with autologous bone grafts from the tibia. In two animals, the implants were inserted under the elevated sinus membrane on both sides. In two animals, the sinus membrane was totally removed. The animals were euthanized after 10 or 45 days. One nonoperated animal representing pristine tissue conditions served as control. The maxillary sinuses with implants were retrieved and further processed for light microscopic ground sections or decalcified sections for immune-histochemical analyses. RESULTS: Bone formation started from the bottom of the sinus floor, sprouting into the granulation tissue along the implant surface under the elevated membrane irrespective of time and surgical technique. Bone formation was not seen in direct conjunction with the sinus membrane. A distinct expression of osteopontin was observed in the serous glands of the lamina propria close to the implant within all groups. CONCLUSION: Bone formation after sinus membrane elevation with or without additional bone grafts starts at the sinus floor and sprouts into the elevated space along the implant surface. The sinus membrane does not seem to present osteoinductive potential in sinus membrane elevation procedures in this study.

Evaluation of a Novel Cone Beam Computed Tomography Scanner for Bone Density Examinations in Preoperative 3D Reconstructions and Correlation with Primary Implant Stability.

BACKGROUND: Bone density examination (BDE) using preoperative cone beam computed tomography (CBCT) might be used to predict primary implant stability in implant patients. PURPOSE: The aim of the study was to validate a novel CBCT scanner in vitro with regard to BDE in preoperative scans and to analyze the in vivo correlation of CBCT scan results with primary implant stability measurements. MATERIALS AND METHODS: A CBCT scanner was validated in vitro with regard to spatial uniformity and linearity of CT numbers (Hounsfield units, HU) by using a series of phantoms and plastic and hydroxyapatite specimens of various densities. Forty-nine patients (27 female and 22 male, mean age 55.6 ± 9.8) were scanned prior to and 1 to 6 months after the placement of 155 dental implants of different lengths and diameters. Mean and peak insertion torque (IT) in Ncm were registered during implant placement. Resonance frequency analysis (RFA) measurements in ISQ units were performed after placement. The second scan was used to export and superimpose the exact positions of bone and implants into the first scan. Virtual probes with the same length as the actual implant were automatically placed at the implant sites, and mean HU values were measured in a 1 mm-wide circular corridor from the tip of the threads and out. RESULTS: The in vitro validation showed high uniformity and linearity of CT numbers (HU). The clinical study showed significant correlations between bone density and ISQ, mean IT, and peak IT, respectively. CONCLUSIONS: The WhiteFox CBCT scanner measures bone density with high accuracy. There is a correlation between bone density and primary implant stability as assessed with IT and RFA measurements. The findings suggest that BDE may be used as an additional feature in treatment-planning software to estimate primary stability at predetermined implant sites.

A Retrospective Study on Immediate Placement of Neoss Implants with Early Loading of Full-Arch Bridges.

BACKGROUND: Full-arch clearances of compromised teeth and placement of implant-supported prostheses is one solution for the prosthetic rehabilitation of partially dentate patients. PURPOSE: To retrospectively evaluate treatment outcomes after full clearance, immediate placement, and early loading of full-arch fixed bridges. MATERIALS AND METHODS: Fifty-five patients subjected to full clearance and placement of 284 Neoss implants (Bimodal™ and Proactive™, Neoss Ltd, Harrogate, UK) in 29 edentulous maxillae and 26 mandibles for early loading (1 to 3 days) of a provisional full-arch bridge were retrospectively evaluated after 1 to 6 years of loading. Osstell™ measurements (Osstell AB, Göteborg, Sweden) were taken at placement and after 3 to 9 months when the provisional bridge was replaced with a permanent one. Marginal bone levels were measured in intraoral radiographs. RESULTS: All patients (100%) wore a fixed bridge at the time of finalizing the study. A total of 18 failures (6.3%) were encountered during the follow-up, giving an overall cumulative survival rate of 93.7%. All failures occurred in the maxilla (10.6%), and no implants were lost in the mandible. More Bimodal™ (9.0%) than Proactive™ (4.1%) implants failed. Failing implants showed a significantly lower mean primary stability than successful ones (p = .015). Failed cases showed a significantly lower average ISQ for all implants (p = .015) and a marked decrease to the second registration, while successful cases showed and maintained high ISQs. The average bone loss after 1 year was 0.8 ± 0.5 mm. CONCLUSIONS: Full-arch clearance of severely diseased teeth followed by immediate placement of Neoss implants, early loading with provisional full-arch bridges, and subsequent permanent bridges is a possible treatment modality for partially dentate patients. Caution with this approach is recommended for the maxilla, as opposed to the mandible.

A 5-year retrospective study on Replace Select Tapered dental implants.

BACKGROUND: Long-term data regarding survival and crestal bone loss for Replace Select Tapered implants (Nobel Biocare AB, Gothenburg, Sweden) are lacking. PURPOSE: The study aims to present the 5-year outcomes from a retrospective analysis of Replace Select Tapered implants placed and restored in consecutive patients. MATERIALS AND METHODS: A total of 88 consecutive patients (32 male, 56 female, mean age 65 ± 12 years) treated by one clinician (PP) were clinically and radiographically evaluated during at least 5 years of function. A total of 271 dental implants (Replace Select Tapered, Nobel Biocare AB) with an oxidized surface (TiUnite, Nobel Biocare AB) had been placed in both jaws (228 in the maxilla, 43 in the mandible). The majority of implants were placed in healed sites (n = 244), while 27 implants were immediately placed in extraction sockets. The majority of implants (n = 262) healed for 3 to 4 months prior to loading, and nine implants were immediately loaded. A total of 121 implant-supported restorations were delivered; 42 single tooth replacements, 61 fixed partial bridges, 14 fixed full bridges, and 4 fixed partial implant-tooth connected bridges. The marginal bone level was measured in intraoral radiographs taken after surgery (baseline), and after 1, 2, 3, 4, and 5 years. RESULTS: Fifty-one patients with 160 implants were followed throughout the study. One implant failed at healing abutment connection 4 months after insertion, resulting in a cumulative survival rate of 99.6%. The average crestal bone loss was 0.9 ± 1.6 mm after 1 year and 0.1 mm ± 2.4 after 5 years. There were 14.8% of measured implants that showed more than 2 mm and 5.2% more than 3 mm bone loss after 5 years, with no progression since the 1-year examination. One patient (2.0%) treated with six implants presented with significant crestal bone loss and recurrent peri-implant purulent infections at all implants. CONCLUSION: The present retrospective 5-year study showed high survival rate and steady crestal bone levels for Replace Select Tapered dental implants.