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.

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.

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.

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.

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.

Radiographic evaluation of modern oral implants with emphasis on crestal bone level and relevance to peri-implant health.

Implant stability and maintenance of stable crestal bone level are prerequisites for the successful long-term function of oral implants, and continuous crestal bone loss constitutes a threat to the longevity of implant-supported prosthetic constructions. The prevalence/incidence and reasons for crestal bone loss are under debate. Some authors regard infection (i.e. peri-implantitis) as the cause for virtually all bone loss, while others see crestal bone loss as an unavoidable phenomenon following surgery and implant loading. Irrespective of the cause of continuous crestal bone loss, correct usage and scientifically sound interpretation of radiographs are of utmost importance for evaluation of oral implants. The periapical radiographic technique is currently the preferred method for evaluating implant health based on bone loss, and digital radiographs allow easy standardization of the image contrast. It is suggested that baseline radiographs should be taken at the time the transmucosal part pierces the mucosal tissues and annually thereafter. The number of unreadable radiographs should be presented in scientific publications to give insights into the quality of the radiographic examination. It is suggested that not only mean values, but also the range of bone levels, should be presented to describe the proportion of implants that show continuous crestal bone loss. In the absence of other clinical symptoms, bleeding on probing around implants seems to be a weak indicator of ongoing or future loss of crestal bone. According to recent longitudinal studies on modern implant surfaces peri-implantitis defined as 'infection with suppuration associated with clinically significant progressing crestal bone loss' occurs with a prevalence of less than 5 % in implants with 10 years in function.

Flapless, CBCT-guided osteotome sinus floor elevation with simultaneous implant installation. I: radiographic examination and surgical technique. A prospective 1-year follow-up.

BACKGROUND: Survival rates of implants placed in transalveolar sinus floor augmentation sites are comparable with those placed in non-augmented sites. Flapless implant surgery can minimize postoperative morbidity, alveolar bone resorption and crestal bone loss. The use of cone beam computerized tomography (CBCT) provides 3D presentations with reduced dose exposure. OBJECTIVES: To evaluate a flapless, CBCT-guided transalveolar sinus floor elevation technique with simultaneous implant installation. MATERIAL AND METHODS: Fourteen consecutive patients in need of maxillary sinus floor augmentation were enrolled in this study. Preoperative CBCT with a titanium screwpost as an indicator at the intended implant position was used to visually guide the flapless surgical procedure. Twenty one implants all with a length of 10 mm and a diameter of 4.1 and 4.8 mm were inserted and followed clinically and with CBCT for 3, 6 and 12 months postoperatively. Intraoral radiographs were taken for comparison. All patients were provided with permanent prosthetic constructions 8-12 weeks after implant surgery. RESULTS: Ten (47.6%) implants were inserted in residual bone of 2.6-4.9 mm and 11 (52.3%) implants were inserted in residual bone of 5-8.9 mm. No implants were lost after surgery and follow-up. There was no marginal bone loss during the follow-up verified by CBCT. The implants penetrated on average 4.4 mm (SD 2.1 mm) into the sinus cavity and the mean bone gain was 3 mm (SD 2.1 mm). CONCLUSION: Flapless transalveolar sinus lift procedures visually guided by preoperative CBCT can successfully be used to enable placement, successful healing and loading of one to three implants in residual bone height of 2.6-8.9 mm. There was no marginal bone loss during the 3-12 months follow-up.

Periapical tissue response after use of intermediate restorative material, gutta-percha, reinforced zinc oxide cement, and mineral trioxide aggregate as retrograde root-end filling materials: a histologic study in dogs.

PURPOSE: To investigate the periapical tissue response of 4 different retrograde root-filling materials, ie, intermediate restorative material, thermoplasticized gutta-percha, reinforced zinc oxide cement (Super-EBA), and mineral trioxide aggregate (MTA), in conjunction with an ultrasonic root-end preparation technique in an animal model. MATERIALS AND METHODS: Vital roots of the third and fourth right mandibular premolars in 6 healthy mongrel dogs were apicectomized and sealed with 1 of the materials using a standardized surgical procedure. After 120 days, the animals were sacrificed and the specimens were analyzed radiologically, histologically, and scanning electron microscopically. The Fisher exact test was performed on the 2 outcome values. RESULTS: Twenty-three sections were analyzed histologically. Evaluation showed better re-establishment of the periapical tissues and generally lower inflammatory infiltration in the sections from teeth treated with the intermediate restorative material and the MTA. New root cement on the resected dentin surfaces was seen on all sections regardless of the used material. New hard tissue formation, directly on the surface of the material, was seen only in the MTA sections. There was no statistical difference in outcome among the tested materials. CONCLUSIONS: The results from this dog model favor the intermediate restorative material and MTA as retrograde fillings when evaluating the bone defect regeneration. MTA has the most favorable periapical tissue response when comparing the biocompatibility of the materials tested.

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.

Sinus bone formation and implant survival after sinus membrane elevation and implant placement: a 1- to 6-year follow-up study.

OBJECTIVES: To investigate the long-term clinical and radiographic results of the maxillary sinus membrane elevation technique where implants were inserted in a void space created by the elevation of the sinus membrane without adding any graft material. MATERIALS AND METHODS: A total of 84 patients were subjected to 96 membrane elevation procedures and simultaneous placement of 239 implants. Changes of intra-sinus and marginal bone height in relation to the implants were measured in intraoral radiographs taken at insertion, after 6 months of healing, after 6 months of loading and then annually. Computerized tomography was performed pre-surgically and 6 months post-surgically. Resonance Frequency Analyses measurements were performed at the time of implants placement, at abutment connection and after 6 months of loading. The implant follow-up period ranged from a minimum of one to a maximum of 6 years after implants loading. RESULTS: All implants were stable after 6 months of healing. A total of three implants were lost during the follow-up period giving a survival rate of 98.7%. Radiography demonstrated on average 5.3±2.1 mm of intra-sinus new bone formation after 6 months of healing. RFA measurements showed adequate primary stability (implant stability quotient 67.4±6.1) and small changes over time. CONCLUSION: Maxillary sinus membrane elevation and simultaneous placement of implants without the use of bone grafts or bone substitutes result in predictable bone formation with a high implant survival rate of 98.7% during a follow-up period of up to 6 years. The intra-sinus bone formation remained stable in the long-term follow-up. It is suggested that the secluded compartment allowed for bone formation according to the principle of guided tissue regeneration. The high implant survival rate of 98.7% indicated that the implants sufficiently supported the fixed bridges throughout the study period. This technique reduces the risks for morbidity related to harvesting of bone grafts and eliminates the costs of grafting materials.

New approach for immediate prosthetic rehabilitation of the edentulous mandible with three implants: a retrospective study.

BACKGROUND: Immediate/early prosthetic rehabilitation of the edentulous mandible with four or more implants for support of a fixed bridge is a well-documented procedure. Only a few studies have reported on the outcome of using three implants for this purpose. AIM: To retrospectively analyze the clinical outcome when using three implants for support of an immediately loaded fixed bridge in the totally edentulous mandible. MATERIALS AND METHODS: In total, 132 patients (67 females and 65 males, mean age 62.6 years, range 35-85 years) treated with 396 implants (Brånemark System) over an 11-year period in one clinic were retrospectively analyzed with regard to implant survival. Implants with both machined and oxidized surface had been used. Eighty percent of the implants were 13 mm in length or longer. The permanent bridge with acrylic teeth was delivered to the patient the same day. The patients were re-called annually for clinical examinations. RESULTS: All patients had been followed for at least 1 year, with the longest follow-up of 10 years and a mean follow-up of 5 years. Thirteen implant failures in 10 patients were experienced, all occurring during the first 12 months of loading. The overall survival rate was 96.7% for implants and 92.4% for original bridges. More machined than oxidized implants failed, 7% vs. 1.2%. Fourteen additional implants were placed at the time of removal of the failed implants when also the fixed bridge was adjusted on the same day. Thus, all patients received and maintained a fixed bridge, except for a few hours in the 10 failure cases when the bridges were adjusted. CONCLUSIONS: This retrospective survival analysis shows that three implants can be used to support a fixed bridge for immediate loading in the edentulous mandible. The study indicated that oxidized implants were more successful than machined ones.

Back-scattered electron imaging and elemental analysis of retrieved bone tissue following sinus augmentation with deproteinized bovine bone or biphasic calcium phosphate.

OBJECTIVES: To compare resorption of a synthetic biphasic calcium phosphate (BCP) bone-graft substitute with deproteinized bovine bone (DBB) used for human maxillary sinus augmentation. MATERIALS AND METHODS: Eleven patients underwent bilateral maxillary sinus floor augmentation with DBB in one side and a BCP (40%beta-tricalcium phosphate (beta-TCP) and 60% hydroxyapatite) in the contralateral side. Simultaneously, with the augmentation on each side a microimplant was placed vertically from the top of the alveolar crest penetrating the residual bone and the grafting material. Eight months after initial surgery the microimplants were retrieved with a surrounding bone core. The composition of residual graft material and surrounding bone was analysed by scanning electron microscopy and energy dispersive X-ray spectroscopy. RESULTS: Residual graft material of both types was present as 10-500 mum particles in direct contact with, or completely surrounded by, newly formed bone; smaller particles were also present in non-mineralized tissue. In the case of BCP the bone-graft substitute interface showed evidence of superficial disintegration of particles into individual grains. Median Ca/P ratios (at.%), determined from >200 discreet sites within residual graft particles and adjacent bone, were: DBB: 1.61 (confidence interval [CI] 1.59-1.64); BCP: 1.5 (CI 1.45-1.52); DBB-augmented bone: 1.62 (CI 1.59-1.66); BCP-augmented bone: 1.52 (CI 1.47-1.55); P=0.028 for DBB vs. BCP and DBB- vs. BCP-augmented bone. The reduction in Ca/P ratio for BCP over the healing period is consistent with the dissolution of beta-TCP and reprecipitation on the surface of calcium-deficient hydroxyapatite. CONCLUSION: The beta-TCP component of BCP may be gradually substituted by calcium-deficient hydroxyapatite over the healing period. This process and superficial degranulation of BCP particles may influence the progress of resorption and healing.

Maxillary sinus floor augmentation and simultaneous implant placement using locally harvested autogenous bone chips and bone debris: a prospective clinical study.

PURPOSE: The aim of this study was to prospectively evaluate the status of implants, marginal bone loss, and outcome of maxillary sinus floor augmentation in patients undergoing maxillary sinus lift and simultaneous implant placement with the use of bone grafts harvested adjacent to the actual surgical site. MATERIALS AND METHODS: Patients in need of maxillary sinus floor augmentation to enable implant placement were enrolled in 2 different groups. In group A, a "bone trap" was used to harvest bone debris during implant preparation with additional bone collected by further drilling adjacent to the implant sites. In group B, a "bone scraper" was used to harvest cortical bone chips from the zygomatic buttress and from the lateral sinus wall before opening of a bony window. All patients were provided a fixed partial denture after a healing period of 3 to 6 months. A total of 61 patients with 81 Straumann implants (Institut Straumann AG, Basel, Switzerland) were assessed, with 17 patients (20 implants) in group A and 44 patients (61 implants) in group B. RESULTS: One implant was lost (in group B) before loading. The survival rate after a follow-up of 12 to 60 months was 98.8%. There was no significant difference in marginal bone loss on the mesial and distal sides of the implant when baseline to 1-year registration was compared with baseline to final registration. During the same time, graft height decreased significantly on the distal apical side of the implants. CONCLUSIONS: Bone grafts can be locally harvested at the site of the maxillary sinus augmentation procedure to enable placement, successful healing, and loading of 1 to 3 implants.

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.

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.

Placement of Brånemark implants in the maxillary tuber region: anatomical considerations, surgical technique and long-term results.

BACKGROUND: Fixture placement in the tuber area is one way to overcome the problem of insufficient bone volume for routine implant surgery in the posterior maxilla due to severe resorption of jawbone and an extensive enlargement of the maxillary sinus. However, little is known about the long-term results. PURPOSE: The aim of this study was to retrospectively evaluate the survival rate and marginal bone conditions at fixtures placed in the tuber region of the maxilla. MATERIAL AND METHODS: Twenty-one patients previously treated with at least one implant in the tuber region of the maxilla were included in this retrospective analysis. A total of 23 standard Brånemark System fixtures with a turned surface had been surgically placed in the tuber regions and 71 additional implants in adjacent areas to support fixed dental bridges. All implants were allowed to heal for 6-8 months before abutment connection and following prosthetic treatment. The patients were radiographed after 1-12 years for evaluation of marginal bone levels. In addition, the relation between the apex of the fixture in the tuberosity area and the posterior border of the maxilla was measured. RESULTS: Twenty of the 21 patients representing 22 tuber and 64 additional implants were radiographically evaluated. No implants in the tuber areas were lost during the follow-up whereas two fixtures in the anterior region had to be removed, one before loading and the other after 4 years of loading not interfering with the prosthesis stability. The mean marginal bone level at tuber implants was situated on average 1.6 mm (SD 1.1, n=22) from the abutment-fixture junction, whilst the other implants showed an average bone level of 1.9 mm (SD 0.8, n=64). The results were similar when comparing partially and totally edentulous patients. CONCLUSION: The present retrospective study shows good clinical outcome with standard Brånemark fixtures placed in the tuber region of the posterior maxilla using a two-stage procedure. In appropriate cases where bone of adequate volume and density is available, our data indicate that the technique can be used as an alternative to more extensive surgery and especially to the sinus lift procedure. However, prospective comparative studies are needed in order to evaluate the efficacy of the described technique for this purpose.

Minimally invasive flapless implant placement: follow-up results from a multicenter study.

BACKGROUND: The placement of implants using a minimally invasive flapless approach has the potential to reduce operative bleeding and postoperative discomfort and minimize crestal bone loss. This article presents follow-up data on a prospective clinical study of implants placed using a flapless procedure. METHODS: The original study reported on 57 patients (33 female patients with an age range of 24 to 86 years; 24 male patients with an age range of 27 to 81 years) recruited from three clinical centers (Tucson, Arizona; Gothenburg, Sweden; and Tel Aviv, Israel) who received 79 implants. After an average of 3 years and 8 months, the patients were contacted and invited to return to their respective clinics for reexamination. Thirty-seven patients with 52 implants returned for a follow-up examination; the remaining 20 patients (27 implants) were not available for reexamination and were considered study drop-outs. RESULTS: The cumulative survival rate at the 3- to 4-year follow-up examination remains at 98.7%, reflecting the loss of one implant. The mean probing depth at abutment connection was 2.2 mm, as reported in the initial study (examination 2 at approximately 2 years postplacement); it was 2.4 mm at the 3- to 4-year second follow-up examination. This change was not clinically or statistically significant. Bleeding score changes also were not significant between the two intervals. The average crestal bone level was -0.7 mm at examination 2 and -0.8 mm at examination 3, a change that approached significance (P <0.06). CONCLUSIONS: Minimally invasive flapless surgery offers patients the possibility of high implant predictability with clinically insignificant crestal bone loss for up to 4 years. Proper diagnosis and treatment planning are key factors in achieving predictable outcomes.

Clinical histology of microimplants placed in two different biomaterials.

PURPOSE: This randomized, controlled study was designed to compare bone formation around microimplants with a sandblasted, acid-etched surface placed at the time of maxillary sinus floor augmentation with a synthetic biphasic calcium phosphate (BCP) or deproteinized bovine bone (DBB). MATERIALS AND METHODS: Nine completely edentulous patients and two partially edentulous patients (six women, five men) with a mean age of 67 years (range, 50 to 79 years) requiring bilateral sinus augmentation were included in the study. The patients were randomized for augmentation with BCP (test) in one side and DBB (control) in the contralateral side. At the time of augmentation, one microimplant on each side was placed vertically from the top of the alveolar crest, penetrating the residual bone and the grafting material. After 8 months of graft healing, at the time of ordinary implant placement, all 22 microimplants were retrieved with a surrounding bone core for histologic analyses. RESULTS: The bone-to-implant contact in the BCP group was 64.6% +/- 9.0%, versus 55.0% +/- 16.0% for the DBB group. The difference was not significant. The corresponding values for the area of newly formed bone in the biopsies were 41.1% +/- 9.8% and 41.6% +/- 14.0% for BCP and DBB, respectively. There were significantly more DBB particles in contact with newly formed bone than BCP particles (87.9 +/- 18.2% versus 53.9 +/- 26.1%; Wilcoxon rank sum test; P = .007). CONCLUSION: In this randomized, controlled clinical trial, new bone formation and bone-to-implant contact around microimplants with a sandblasted, acid-etched surface was found to be equivalent between sinuses augmented with BCP or DBB. Significantly more DBB particles than BCP particles were in contact with newly formed bone, but the clinical relevance of this has yet to be established.

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.

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.