Teaching and assessment of implant dentistry in undergraduate and postgraduate education: a European consensus

This paper constitutes a summary of the consensus documents agreed at the First European Workshop on Implant Dentistry University Education held in Prague on 19-22 June 2008. Implant dentistry is becoming increasingly important treatment alternative for the restoration of missing teeth, as patients expectations and demands increase. Furthermore, implant related complications such as peri-implantitis are presenting more frequently in the dental surgery. This consensus paper recommends that implant dentistry should be an integral part of the undergraduate curriculum. Whilst few schools will achieve student competence in the surgical placement of implants this should not preclude the inclusion of the fundamental principles of implant dentistry in the undergraduate curriculum such as the evidence base for their use, indications and contraindications and treatment of the complications that may arise. The consensus paper sets out the rationale for the introduction of implant dentistry in the dental curriculum and the knowledge base for an undergraduate programme in the subject. It lists the competencies that might be sought without expectations of surgical placement of implants at this stage and the assessment methods that might be employed. The paper also addresses the competencies and educational pathways for postgraduate education in implant dentistry.

Bone response to loaded implants with non-matching implant-abutment diameters in the canine mandible

BACKGROUND: One way to evaluate various implant restorations is to measure the amount of bone change that occurs at the crestal bone. The objective of this study was to histologically evaluate the alveolar bone change around a bone-level, non-matching implant-abutment diameter configuration that incorporated a horizontal offset and a Morse taper internal connection. METHODS: The study design included extraction of all mandibular premolars and first molars in five canines. After 3 months, 12 dental implants were placed at three levels in each dog: even with the alveolar crest, 1 mm above the alveolar crest, and 1 mm below the alveolar crest. The implants were submerged on one side of the mandible. On the other side, healing abutments were exposed to the oral cavity (non-submerged). Gold crowns were attached 2 months after implant placement. The dogs were sacrificed 6 months postloading, and specimens were processed for histologic and histometric analyses. RESULTS: Evaluation of the specimens indicated that the marginal bone remained near the top of the implants under submerged and non-submerged conditions. The amount of bone change for submerged implants placed even with, 1 mm below, and 1 mm above the alveolar crest was -0.34, -1.29, and 0.04 mm, respectively (negative values indicate bone loss). For non-submerged implants, the respective values were -0.38, -1.13, and 0.19 mm. For submerged and non-submerged implants, there were significant differences in the amount of bone change among the three groups (P <0.05). The percentage of bone-to-implant contact for submerged implants was 73.3%, 71.8%, and 71.5%. For non-submerged implants, the respective numbers were 73.2%, 74.5%, and 76%. No significant differences occurred with regard to the percentage of bone contact. CONCLUSIONS: Minimal histologic bone loss occurred when dental implants with non-matching implant-abutment diameters were placed at the bone crest and were loaded for 6 months in the canine. The bone loss was significantly less (five- to six-fold) than that reported for bone-level implants with matching implant-abutment diameters (butt-joint connections).

Effects of decontamination and implant surface characteristics on re-osseointegration following treatment of peri-implantitis

BACKGROUND: Although considerable bone fill may occur following treatment of peri-implantitis, re-osseointegration appears to be limited and unpredictable. Objectives: To evaluate the effects of various decontamination techniques and implant surface configurations on re-osseointegration of contaminated dental implants. MATERIAL AND METHODS: Three months after tooth extraction, implants consisting of a basal part and an exchangeable intraosseous implant cylinder (EIIC) were placed in the mandibles of dogs. The EIIC was machined (M), sandblasted and acid-etched (SLA), or titanium plasma sprayed (TPS). Ligature-induced peri-implantitis was initiated 8 weeks post-implantation and lasted until bone loss reached the junction of the two implant parts. Three treatment modalities were applied: (T1) the EIIC was exchanged for a pristine EIIC; (T2) the EIIC was sprayed in situ with saline; and (T3) the EIIC was removed, cleansed outside the mouth by spraying with saline, steam-sterilized, and remounted. A collagen barrier was placed over each fixture, and 3 months later, samples were processed for histology and histomorphometry. RESULTS: T2 revealed the highest bone-to-implant contact (BIC) level (significantly better than T1 and T3). T2 also yielded the highest bone crest level (significantly better than T1), followed by T3 (significantly better than T1). SLA showed the highest BIC level (significantly better than M), followed by TPS. There were no statistically significant differences in bone crest height between implant types. CONCLUSIONS: Both SLA implants and in situ cleansing resulted in the best re-osseointegration and bone fill of previously contaminated implants.

Failures and complications in patients with birth defects restored with fixed dental prostheses and single crowns on teeth and/or implants

OBJECTIVES: To assess retrospectively, over at least 5 years, the incidences of technical and biological complications and failures in young adult patients with birth defects affecting the formation of teeth. MATERIAL AND METHODS: All insurance cases with a birth defect that had crowns and fixed dental prostheses (FDPs) inserted more than 5 years ago were contacted and asked to participate in a reexamination. RESULTS: The median age of the patients was 19.3 years (range 16.6-24.7 years) when prosthetic treatment was initiated. Over the median observation period of 15.7 years (range 7.4-24.9 years) and considering the treatment needs at the reexamination, 19 out of 33 patients (58%) with reconstructions on teeth remained free from all failures or complications. From the patients with FDPs and single unit crowns (SCs) on implants followed over a median observation period of 8 years (range 4.6-15.3 years), eight out of 17% or 47% needed a retreatment or repair at some point due to a failure or a complication. From the three groups of patients, the cases with amelogenesis/dentinogenesis imperfecta demonstrated the highest failure and complication rates. In the cases with cleft lip, alveolus and palate (CLAP) or hypodontia/oligodontia, 71% of the SCs and 73% of the FDPs on teeth (FDP T) remained complication free over a median observation period of about 16 years. Sixty-two percent of the SCs and 64% of the FDPs on implants remained complication free over 8 years. Complications occurred earlier with implant-supported reconstructions. CONCLUSIONS: Because healthy, pristine teeth can be left unprepared, implant-supported SCs and FDPs are the treatment choice in young adults with birth defects resulting in tooth agenesis and in whom the edentulous spaces cannot be closed by means of orthodontic therapy. However, the trend for earlier and more frequent complications with implant-supported reconstructions in young adults, expecting many years of function with the reconstructions, has to be weighed against the benefits of keeping teeth unprepared. In cases with CLAP in which anatomical conditions render implant placement difficult and in which teeth adjacent to the cleft require esthetic corrections, the conventional FDP T still remains the treatment of choice.

Removable dentures with implant support in strategic positions followed for up to 8 years

PURPOSE: The aim of this study was to analyze prosthetic maintenance in partially edentulous patients with removable prostheses supported by teeth and strategic implants. MATERIALS AND METHODS: Sixty patients with removable partial prostheses and combined tooth-implant support were identified within the time period from 1998 to 2006. One group consisted of 42 patients (planned group) with a reduced residual dentition and in need of removable partial dentures (RPDs) or overdentures in the maxilla and/or mandible. They were admitted consecutively for treatment. Due to missing teeth in strategic important positions, one or two implants were placed to improve symmetrical denture support and retention. The majority of residual teeth exhibited an impaired structural integrity and therefore were provided with root copings for denture retention. A few vital teeth were used for telescopic crowns. The anchorage system for the strategic implants was selected accordingly. A second group of 18 patients (repair group) wearing RPDs with the loss of one abutment tooth due to biologic or mechanical failure was identified. These abutment teeth were replaced by 21 implants, and patients continued to wear their original prostheses. The observation time for planned and repair groups was 12 months to 8 years. All patients followed a regular maintenance schedule. Technical or biologic complications with supporting teeth or implants and prosthetic service were registered regularly. RESULTS: Three maxillary implants were lost after loading and three roots with copings had to be removed. Biologic problems included caries and periodontal/peri-implant infection with a significantly higher incidence in the repair group (P < .05). Technical complications with the dentures were rather frequent in both groups, mostly related to the anchorage system (matrices) of root copings and implants. Maintenance and complications were observed more frequently in the first year after delivery of the denture than in the following 3 years (P < .05). No denture had to be remade. CONCLUSIONS: The placement of a few implants allows for maintaining a compromised residual dentition for support of RPDs. The combination of root and implant support facilitates treatment planning and enhances designing the removable denture. It also proves to be a practical rescue method. Technical problems with the anchorage system were frequent, particularly in the first year after delivery of the dentures.

Randomized controlled trial comparing a variable-thread novel tapered and a standard tapered implant: interim one-year results

STATEMENT OF PROBLEM: A tapered implant with continuously changing threads purported to provide stable tissue support and allow immediate function has been developed. Treatment success and stabilization of supporting tissues over time require documentation. PURPOSE: The purpose of this prospective, randomized, controlled, multicenter study was to evaluate changes in bone level and soft tissue behavior between the novel implant (NobelActive/NA) and a standard tapered implant (NobelReplace Tapered Groovy/NR) with regard to immediate function. MATERIAL AND METHODS: A total of 177 patients randomly allocated to 3 treatment groups (2 different test implant groups: NA Internal (n=117; internal connection) and External (n=82), and 1 standard treatment group, NR (n=126)) received 325 implants. Implants were placed into healed sites, and all but 6 implants were immediately nonocclusally loaded. Clinical and radiographic evaluations of treatment success, crestal bone levels, and soft tissue changes were performed at the time of placement and after 3, 6, and 12 months. Log-Rank test was used to analyze the differences in survival rate. Marginal bone level was compared using the Kruskal-Wallis test and Mann-Whitney U-test (alpha=.05). RESULTS: One-year cumulative survival rates were comparable (96.6% for NA Internal; 96.3% for NA External; 97.6% for NR; P=.852; Log-Rank). Mean (SD) change in bone level was -0.95 mm (1.37) for NA Internal, -0.64 mm (0.97) for NA External, and -0.63 mm (1.18) for NR (P=.589; Kruskal-Wallis). Stable soft tissues and significantly increased papilla scores (P<.001; Wilcoxon signed-rank) were observed for all implant types. CONCLUSIONS: The novel implants showed high survival rates as well as stable bone and soft tissue levels after 1 year, and may be recommended for clinical use, even under immediate function.

[Rehabilitation of a periodontally compromised dentition with implant-supported zirconia bridges. Case report]

Clinical aspects of reconstruction with fix prosthesis and dental implants in a patient with a history of periodontitis is shown. A successful stabilization and rehabilitation of the periodontally involved dentition can be achieved with tooth-worn crown and bridge reconstructions. From a functional and aesthetic point of view the result may not be satisfying due to mobility and overlength of the teeth and open approximal spaces. Today, dentist and patient have often to weigh if teeth shall be maintained or replaced by dental implants. Thereby, both must be aware of the fact that in complex cases long-term success and aesthetic outcome may be difficult to predict. An intense discussion with the patient on his expectations, invasive treatment, risks with regard to biologic and prosthetic aspects is mandatory and must be based on the best scientific evidence available. The present case report shows different considerations and describes a radical solution which meets the patient's needs and is based on modern CAD-CAM technology.

BMP-2 liberated from biomimetic implant coatings induces and sustains direct ossification in an ectopic rat model

INTRODUCTION: Using a rat model, we evaluated the kinetics and histomorphometry of ectopic bone formation in association with biomimetic implant coatings containing BMP-2. MATERIALS AND METHODS: One experimental and three control groups were set up: titanium-alloy discs coated with a biomimetically co-precipitated layer of calcium phosphate and BMP-2 [1.7 microg per disc (incorporated-BMP group)]; uncoated discs (control); discs biomimetically coated with a layer of calcium phosphate alone (control); and discs biomimetically coated with a layer of calcium phosphate bearing superficially adsorbed BMP-2 [0.98 microg per disc (control)]. Discs (n = 6 per group) were implanted subcutaneously in rats and retrieved at 7-day intervals over a period of 5 weeks for kinetic, histomorphometrical, morphological and histochemical analyses. RESULTS: In the incorporated-BMP-2 group, osteogenic activity was first observed 2 weeks after implantation and thereafter continued unabated until the end of the monitoring period. The net weekly rates of bone formation per disc were 5.8 mm3 at 2 weeks and 3.64 mm3 at 5 weeks. The total volumes of bone formed per disc at these junctures were 5.8 mm3 and 10.3 mm3, respectively. Bone tissue, which was formed by a direct ossification mechanism, was deposited at distances of up to 340 microm from the implant surfaces. The biomimetic coatings were degraded gradually, initially by foreign body giant cells alone and then also by osteoclasts. Forty percent of the coating material (and thus presumably of the incorporated BMP-2) remained at the end of the monitoring period. Hence, 60% of the incorporated BMP-2 had been released. At this 5-week juncture, no bone tissue was associated with any of the control implants. CONCLUSION: BMP-2 incorporated into biomimetic calcium phosphate coatings is capable not only of inducing bone formation at an ectopic site in vivo but also of doing so with a very high potency at a low pharmacological level, and of sustaining this activity for a considerable period of time. The sustainment of osteogenic activity is of great clinical importance for the osseointegration of dental and orthopedic implants.

Long-term outcomes of dental implants with a titanium plasma-sprayed surface: a 20-year prospective case series study in partially edentulous patients

BACKGROUND Long-term studies of ≥10 years are important milestones to get a better understanding of potential factors causing implant failures or complications. PURPOSE The present study investigated the long-term outcomes of titanium dental implants with a rough, microporous surface (titanium plasma sprayed [TPS]) and the associated biologic and technical complications in partially edentulous patients with fixed dental prostheses over a 20-year follow-up period. MATERIALS AND METHODS Sixty-seven patients, who received 95 implants in the 1980s, were examined with well-established clinical and radiographic parameters. Based on these findings, each implant was classified as either successful, surviving, or failed. RESULTS Ten implants in nine patients were lost during the observation period, resulting in an implant survival rate of 89.5%. Radiographically, 92% of the implants exhibited crestal bone loss below 1 mm between the 1- and 20-year follow-up examinations. Only 8% yielded peri-implant bone loss of >1 mm and none exhibited severe bone loss of more than 1.8 mm. During the observation period, 19 implants (20%) experienced a biologic complication with suppuration. Of these 19 implants, 13 implants (13.7%) had been treated and were successfully maintained over the 20-year follow-up period. Therefore, the 20-year implant success rate was 75.8 or 89.5% depending on the different success criteria. Technical complications were observed in 32%. CONCLUSION The present study is the first to report satisfactory success rates after 20 years of function of dental implants with a TPS surface in partially edentulous patients.

Long-term stability of early implant placement with contour augmentation

In this prospective case series study, 20 patients with an implant-borne single crown following early implant placement with simultaneous contour augmentation were followed for 6 years. Clinical, radiologic, and esthetic parameters were assessed. In addition, cone beam computed tomography (CBCT) was used at 6 years to examine the facial bone wall. During the study period, all 20 implants were successfully integrated, and the clinical parameters remained stable over time. Pleasing esthetic outcomes were noted, as assessed by the pink esthetic scores. None of the implants developed mucosal recession of 1 mm or more. The periapical radiographs yielded stable peri-implant bone levels, with a mean DIB of 0.44 mm at 6 years. The CBCT scans showed that all 20 implants had a detectable facial bone wall at 6 years, with a mean thickness of around 1.9 mm. In summary, this prospective case series study demonstrated stable peri-implant hard and soft tissues for all 20 implants, and pleasing esthetic outcomes overall. The follow-up of 6 years confirmed that the risk for mucosal recession is low with early implant placement. In addition, contour augmentation with guided bone regeneration (GBR) was able to establish and maintain a facial bone wall in all 20 patients.

Anatomical characteristics and dimensions of edentulous sites in the posterior maxillae of patients referred for implant therapy

The purpose of this study was to analyze the width and height of edentulous sites in the posterior maxilla using cone beam computed tomography (CBCT) images from patients referred for implant therapy. A total of 122 CBCT scans were included in the analysis, resulting in a sample size of 252 edentulous sites. The orofacial crest width was measured in coronal slices, perpendicular to the alveolar ridge. The bone height was analyzed in the respective sagittal slices. Additionally, the following secondary outcome parameters were evaluated: the morphology of the sinus floor, the presence of septa in the maxillary sinus, and the thickness of the sinus membrane. The mean crest width for all analyzed sites was 8.28 mm, and the mean bone height was 7.22 mm. The percentage of patients with a crest width of less than 6 mm was 27% in premolar sites and 7.8% in molar sites. The bone height decreased from premolar to molar areas, with a high percentage of first and second molar sites exhibiting a bone height of less than 5 mm (54.12% and 44.64%, respectively). Regarding the morphology of the sinus floor, 53% of the edentulous sites exhibited a flat configuration. A septum was present in 67 edentulous sites (26.59%). Analysis of the sinus membrane revealed 88 sites (34.9%) with increased mucosal thickness (> 2 mm). For the crest width, the location of the edentulous site and the morphology of the sinus floor were both statistically significant variables. For the crest width and mean bone height, the location of the edentulous site and the morphology of the sinus floor were both statistically significant variables. The study confirmed that a high percentage of edentulous sites in the posterior maxilla do require sinus floor elevation to allow the placement of dental implants. Therefore, a detailed three-dimensional radiograph using CBCT is indicated in most patients for proper treatment planning.

Piezoelectric alveolar ridge-splitting technique with simultaneous implant placement: a cohort study with 2-year radiographic results

PURPOSE Extended grafting procedures in atrophic ridges are invasive and time-consuming and increase cost and patient morbidity. Therefore, ridge-splitting techniques have been suggested to enlarge alveolar crests. The aim of this cohort study was to report techniques and radiographic outcomes of implants placed simultaneously with a piezoelectric alveolar ridge-splitting technique (RST). Peri-implant bone-level changes (ΔIBL) of implants placed with (study group, SG) or without RST (control group, CG) were compared. MATERIALS AND METHODS Two cohorts (seven patients in each) were matched regarding implant type, position, and number; superstructure type; age; and gender and received 17 implants each. Crestal implant bone level (IBL) was measured at surgery (T0), loading (T1), and 1 year (T2) and 2 years after loading (T3). For all implants, ΔIBL values were determined from radiographs. Differences in ΔIBL between SG and CG were analyzed statistically (Mann-Whitney U test). Bone width was assessed intraoperatively, and vertical bone mapping was performed at T0, T1, and T3. RESULTS After a mean observation period of 27.4 months after surgery, the implant survival rate was 100%. Mean ΔIBL was -1.68 ± 0.90 mm for SG and -1.04 ± 0.78 mm for CG (P = .022). Increased ΔIBL in SG versus CG occurred mainly until T2. Between T2 and T3, ΔIBL was limited (-0.11 ± 1.20 mm for SG and -0.05 ± 0.16 mm for CG; P = .546). Median bone width increased intraoperatively by 4.7 mm. CONCLUSIONS Within the limitations of this study, it can be suggested that RST is a well-functioning one-stage alternative to extended grafting procedures if the ridge shows adequate height. ΔIBL values indicated that implants with RST may fulfill accepted implant success criteria. However, during healing and the first year of loading, increased IBL alterations must be anticipated.

In vitro precision of fit of computer-aided designed and computer-aided manufactured titanium screw-retained fixed dental prostheses before and after ceramic veneering

OBJECTIVE To compare the precision of fit of full-arch implant-supported screw-retained computer-aided designed and computer-aided manufactured (CAD/CAM) titanium-fixed dental prostheses (FDP) before and after veneering. The null-hypothesis was that there is no difference in vertical microgap values between pure titanium frameworks and FDPs after porcelain firing. MATERIALS AND METHODS Five CAD/CAM titanium grade IV frameworks for a screw-retained 10-unit implant-supported reconstruction on six implants (FDI tooth positions 15, 13, 11, 21, 23, 25) were fabricated after digitizing the implant platforms and the cuspid-supporting framework resin pattern with a laser scanner (CARES(®) Scan CS2; Institut Straumann AG, Basel, Switzerland). A bonder, an opaquer, three layers of porcelain, and one layer of glaze were applied (Vita Titankeramik) and fired according to the manufacturer's preheating and fire cycle instructions at 400-800°C. The one-screw test (implant 25 screw-retained) was applied before and after veneering of the FDPs to assess the vertical microgap between implant and framework platform with a scanning electron microscope. The mean microgap was calculated from interproximal and buccal values. Statistical comparison was performed with non-parametric tests. RESULTS All vertical microgaps were clinically acceptable with values <90 μm. No statistically significant pairwise difference (P = 0.98) was observed between the relative effects of vertical microgap of unveneered (median 19 μm; 95% CI 13-35 μm) and veneered FDPs (20 μm; 13-31 μm), providing support for the null-hypothesis. Analysis within the groups showed significantly different values between the five implants of the FDPs before (P = 0.044) and after veneering (P = 0.020), while a monotonous trend of increasing values from implant 23 (closest position to screw-retained implant 25) to 15 (most distant implant) could not be observed (P = 0.169, P = 0.270). CONCLUSIONS Full-arch CAD/CAM titanium screw-retained frameworks have a high accuracy. Porcelain firing procedure had no impact on the precision of fit of the final FDPs. All implant microgap measurements of each FDP showed clinically acceptable vertical misfit values before and after veneering. Thus, the results do not only show accurate performance of the milling and firing but show also a reproducible scanning and designing process.

Improvements in Implant Dentistry over the Last Decade: Comparison of Survival and Complication Rates in Older and Newer Publications

Purpose: The objective of this systematic review was to assess and compare the survival and complication rates of implant-supported prostheses reported in studies published in the year 2000 and before, to those reported in studies published after the year 2000. Materials and Methods: Three electronic searches complemented by manual searching were conducted to identify 139 prospective and retrospective studies on implant-supported prostheses. The included studies were divided in two groups: a group of 31 older studies published in the year 2000 or before, and a group of 108 newer studies published after the year 2000. Survival and complication rates were calculated using Poisson regression models, and multivariable robust Poisson regression was used to formally compare the outcomes of older and newer studies. Results: The 5-year survival rate of implant-supported prostheses was significantly increased in newer studies compared with older studies. The overall survival rate increased from 93.5% to 97.1%. The survival rate for cemented prostheses increased from 95.2% to 97.9%; for screw-retained reconstruction, from 77.6% to 96.8%; for implant-supported single crowns, from 92.6% to 97.2%; and for implant-supported fixed dental prostheses (FDPs), from 93.5% to 96.4%. The incidence of esthetic complications decreased in more recent studies compared with older ones, but the incidence of biologic complications was similar. The results for technical complications were inconsistent. There was a significant reduction in abutment or screw loosening by implant-supported FDPs. On the other hand, the total number of technical complications and the incidence of fracture of the veneering material was significantly increased in the newer studies. To explain the increased rate of complications, minor complications are probably reported in more detail in the newer publications. Conclusions: The results of the present systematic review demonstrated a positive learning curve in implant dentistry, represented in higher survival rates and lower complication rates reported in more recent clinical studies. The incidence of esthetic, biologic, and technical complications, however, is still high. Hence, it is important to identify these complications and their etiology to make implant treatment even more predictable in the future.

Soft tissue wound healing around teeth and dental implants.

AIM To provide an overview on the biology and soft tissue wound healing around teeth and dental implants. MATERIAL AND METHODS This narrative review focuses on cell biology and histology of soft tissue wounds around natural teeth and dental implants. RESULTS AND CONCLUSIONS The available data indicate that: (a) Oral wounds follow a similar pattern. (b) The tissue specificities of the gingival, alveolar and palatal mucosa appear to be innately and not necessarily functionally determined. (c) The granulation tissue originating from the periodontal ligament or from connective tissue originally covered by keratinized epithelium has the potential to induce keratinization. However, it also appears that deep palatal connective tissue may not have the same potential to induce keratinization as the palatal connective tissue originating from an immediately subepithelial area. (d) Epithelial healing following non-surgical and surgical periodontal therapy appears to be completed after a period of 7–14 days. Structural integrity of a maturing wound between a denuded root surface and a soft tissue flap is achieved at approximately 14-days post-surgery. (e) The formation of the biological width and maturation of the barrier function around transmucosal implants requires 6–8 weeks of healing. (f) The established peri-implant soft connective tissue resembles a scar tissue in composition, fibre orientation, and vasculature. (g) The peri-implant junctional epithelium may reach a greater final length under certain conditions such as implants placed into fresh extraction sockets versus conventional implant procedures in healed sites.