Clinical and microbiological analysis of subjects treated with Brånemark or AstraTech implants: a 7-year follow-up study

AIMS: To assess the impact of different implant systems on the clinical conditions and the microbiota at implants, and whether the presence of bacteria at tooth sites was predictive of the presence at implant sites. MATERIALS AND METHODS: Subjects with either AstraTech or Brånemark in function for 7 years were enrolled. Sub-gingival bacterial samples at tooth and implant sites were collected with sterile endodontic paper points, and analyzed by the checkerboard DNA-DNA hybridization method (40 species). RESULTS: Fifty-four subjects, 27 supplied with AstraTech (n=132 implants) and 27 with Brånemark (n=102) implants, were studied. Test tooth sites had significantly less evidence of bleeding on probing (P<0.001) and presence of plaque (P<0.001) than implant test sites. Implant sites presented with deeper probing pocket depth than tooth sites (mean difference: 1.1 mm, standard error of differences: 0.08, 95% confidence intervals (CI): 0.9-1.3, P<0.001). Tannerella forsythia (P<0.05), Capnocytophaga sputigena (P<0.05), Actinomyces israelii (P<0.05) and Lactobacillus acidophilus (P<0.05) were found at higher levels at tooth surfaces. No differences in bacterial load for any species were found between the two implant systems. The odds of being present/absent at tooth and implants sites were only significant for Staphylococcus aureus [odds ratio (OR): 5.2 : 1, 95% CI: 1.4-18.9, P<0.01]. CONCLUSIONS: After 7 years in function, implants presented with deeper probing depths than teeth. S. aureus was commonly present at both teeth and implants sites. S. aureus at tooth sites was predictive of also being present at implant sites.

Enhancement of titanium implants via bioengineered periodontal tissues

Osseointegration of titanium dental implants into the jaw bone, which is required for maintenance of the implant in the jaw, results in ankylosis. Dental implants are therefore very unlike natural teeth, which exhibit significant movement in response to mechanical forces. The ability to generate periodontal ligament (PDL) tissues onto dental implants would better mimic the functional characteristics of natural teeth, and would likely improve implant duration and function. OBJECTIVES: The objective of this study was to investigate the feasibility of bioengineering PDL tissues onto titanium implant surfaces. METHODS: Bilateral maxillary first and second molars of 8-week old rats were extracted and used to generate single cell suspensions of PDL tissues, which were expanded in culture. Immunohistochemistry and RT-PCR were used to identify putative PDL progenitor/stem cell populations and characterize stem cell properties, including self-renewal, multipotency and stem cell maker expression. Cultured rPDL cells were harvested at third passage, seeded onto Matrigel-coated titanium implants (1.75 mm x 1 mm), and placed into healed M1/M2 extraction sites. Non-cell seeded Matrigel-coated titanium implants served as negative controls. Implants were harvested after 8, 12, or 18 weeks. RESULTS: Cultured rPDL cells expressed the mesenchymal stem-cell marker STRO-1. Under defined culture conditions, PDL cells differentiated into adipogenic, neurogenic and osteogenic lineages. While control implants were largely surrounded by alveolar bone, experimental samples exhibited fibrous PDL-like tissues, and perhaps cementum, on the surface of experimental implants. CONCLUSIONS: PDL contains stem cells that can generate cementum/PDL-like tissue in vivo. Transplantation of these cells might hold promise as a therapeutic approach for the bioengineering of PDL tissues onto titanium implant. Further refinement of this method will likely result in improved dental implant strategies for use of autologous PDL tissue regeneration in humans. This research was supported by CIMIT, and NIH/NIDCR grant DE016132 (PCY), and TEACRS (YL).

Early loading of sandblasted and acid-etched implants: a randomized-controlled double-blind split-mouth study. Five-year results

OBJECTIVES: The aim of the present split-mouth study is to assess the peri-implant conditions around early-loaded sandblasted and acid-etched (SLA) implants, 5 years after abutment connection and to compare, in the same patients, the results obtained with a standard protocol using identical implants with a TPS surface. MATERIAL AND METHODS: Surgical procedure was performed by the same operator and was identical at test (SLA) and control (TPS) sites, in 32 healthy patients. Abutment connection was carried out at 35 N cm 6 weeks postsurgery for test sites and 12 weeks for the controls. Patients were seen regularly, for control and professional cleaning. At 60 months, clinical measures and radiographic bone changes were recorded by the same operator, blind to the type of surface of the implant, on 27 patients, as five patients were lost to follow-up. RESULTS: A total number of 106 implants were examined. No implant was lost. No significant differences were found with respect to the presence of plaque [modified plaque index (mPI) 0.27+/-0.56 vs. 0.32+/-0.54], bleeding on probing (29% vs. 32%), mean pocket depth (3.2+/-1 vs. 3.2+/-1 mm) or mean marginal bone loss (0.32+/-1.04 vs. 0.44+/-1.12 mm) between test and control. Four implants that presented 'spinning' at the time of abutment connection presented no significant differences from the rest of the test sites. CONCLUSION: The results of this prospective study confirm that SLA implants, under defined conditions, are suitable for early loading at 6 weeks in both the mandible and the maxilla. Limited implant spinning, occasionally found at abutment connection, produces no detrimental effect on the clinical outcome when properly handled.

Efficacy of panoramic radiographs in the preoperative planning of posterior mandibular implants: a prospective clinical study of 1527 consecutively treated patients

OBJECTIVES: Various imaging techniques, including conventional radiography and computed tomography, are proposed to localize the mandibular canal prior to implant surgery. The aim of this study is to determine the incidence of altered mental nerve sensation after implant placement in the posterior segment of the mandible when a panoramic radiograph is the only preoperative imaging technique used. MATERIAL AND METHODS: The study included 1527 partially and totally edentulous patients who had consecutively received 2584 implants in the posterior segment of the mandible. Preoperative bone height was evaluated from the top of the alveolar crest to the superior border of the mandibular canal on a standard panoramic radiograph. A graduated implant scale from the implant manufacturer was used and 2 mm were subtracted as a safety margin to determine the length of the implant to be inserted. RESULTS: No permanent sensory disturbances of the inferior alveolar nerve were observed. There were two cases of postoperative paresthesia, representing 2/2584 (0.08%) of implants inserted in the posterior segment of the mandible or 2/1527 (0.13%) of patients. These sensory disturbances were minor, lasted for 3 and 6 weeks and resolved spontaneously. CONCLUSIONS: Panoramic examination can be considered a safe preoperative evaluation procedure for routine posterior mandibular implant placement. Panoramic radiography is a quick, simple, low-cost and low-dose presurgical diagnostic tool. When a safety margin of at least 2 mm above the mandibular canal is respected, panoramic radiography appears to be sufficient to evaluate available bone height prior to insertion of posterior mandibular implants; cross-sectional imaging techniques may not be necessary.

Biomechanical comparison of different surface modifications for dental implants

Purpose: A satisfactory clinical outcome in dental implant treatment relies on primary stability for immediate load bearing. While the geometric design of an implant contributes to mechanical stability, the nature of the implant surface itself is also critically important. Biomechanical and microcomputerized tomographic evaluation of implant osseointegration was performed to compare alternative structural, chemical and biochemical, and/or pharmaceutical surface treatments applied to an identical established implant design. Materials and Methods: Dental implants with the same geometry but with 6 different surface treatments were tested in vivo in a sheep model (pelvis). Peri-implant bone density and removal torque were compared at 2, 4, and 8 weeks after implantation. Implant surfaces tested were: sandblasted and acid-etched titanium (Ti), sandblasted and etched zirconia, Ti coated with calcium phosphate (CaP), Ti modified via anodic plasma-chemical treatment (APC), bisphosphonate-coated Ti (Ti + Bisphos), and Ti coated with collagen containing chondroitin sulfate (CS). Results: All dental implants were well integrated at the time of sacrifice. There were no significant differences observed in peri-implant bone density between implant groups. After 8 weeks of healing, removal torque values for Ti, Ti + CaP, Ti + Bisphos, and Ti + collagen + CS were significantly higher than those for zirconia and Ti + APC. Conclusions: Whereas the sandblasted/acid-etched Ti implant can still be considered the reference standard surface for dental implants, functional surface modifications such as bisphosphonate or collagen coating seem to enhance early peri-implant bone formation and should be studied further.

Survival and failure rates of orthodontic temporary anchorage devices: a systematic review

AIM: The purpose of this study was to systematically review the literature on the survival rates of palatal implants, Onplants((R)), miniplates and mini screws. MATERIAL AND METHODS: An electronic MEDLINE search supplemented by manual searching was conducted to identify randomized clinical trials, prospective and retrospective cohort studies on palatal implants, Onplants((R)), miniplates and miniscrews with a mean follow-up time of at least 12 weeks and of at least 10 units per modality having been examined clinically at a follow-up visit. Assessment of studies and data abstraction was performed independently by two reviewers. Reported failures of used devices were analyzed using random-effects Poisson regression models to obtain summary estimates and 95% confidence intervals (CI) of failure and survival proportions. RESULTS: The search up to January 2009 provided 390 titles and 71 abstracts with full-text analysis of 34 articles, yielding 27 studies that met the inclusion criteria. In meta-analysis, the failure rate for Onplants((R)) was 17.2% (95% CI: 5.9-35.8%), 10.5% for palatal implants (95% CI: 6.1-18.1%), 16.4% for miniscrews (95% CI: 13.4-20.1%) and 7.3% for miniplates (95% CI: 5.4-9.9%). Miniplates and palatal implants, representing torque-resisting temporary anchorage devices (TADs), when grouped together, showed a 1.92-fold (95% CI: 1.06-2.78) lower clinical failure rate than miniscrews. CONCLUSION: Based on the available evidence in the literature, palatal implants and miniplates showed comparable survival rates of >or=90% over a period of at least 12 weeks, and yielded superior survival than miniscrews. Palatal implants and miniplates for temporary anchorage provide reliable absolute orthodontic anchorage. If the intended orthodontic treatment would require multiple miniscrew placement to provide adequate anchorage, the reliability of such systems is questionable. For patients who are undergoing extensive orthodontic treatment, force vectors may need to be varied or the roots of the teeth to be moved may need to slide past the anchors. In this context, palatal implants or miniplates should be the TADs of choice.

Early loading of nonsubmerged titanium implants with a chemically modified sand-blasted and acid-etched surface: 6-month results of a prospective case series study in the posterior mandible focusing on peri-implant crestal bone changes and implant stability quotient (ISQ) values

PURPOSE: The aim of this prospective case series study was to evaluate the short-term success rates of titanium screw-type implants with a chemically modified sand-blasted and acid-etched (mod SLA) surface after 3 weeks of healing. MATERIAL AND METHODS: A total of 56 implants were inserted in the posterior mandible of 40 partially edentulous patients exhibiting bone densities of class I to III. After a healing period of 3 weeks, all implants were functionally loaded with a screw-retained crown or fixed dental prosthesis. The patients were recalled at weeks 4, 7, 12, and 26 for monitoring and assessment of clinical and radiological parameters, including implant stability quotient (ISQ) measurements. RESULTS: None of the implants failed to integrate. However, two implants were considered "spinners" at day 21 and left unloaded for an extended period. Therefore, 96.4% of the inserted implants were loaded according to the protocol tested. All 56 implants including the "spinners" showed favorable clinical and radiographic findings at the 6-month follow-up examination. The ISQ values increased steadily throughout the follow-up period. At the time of implant placement, the range of ISQ values exhibited a mean of 74.33, and by week 26, a mean value of 83.82 was recorded. Based on strict criteria, all 56 implants were considered successfully integrated, resulting in a 6-month survival and success rate of 100.0%. CONCLUSION: This prospective study using an early-loading protocol after 3 weeks of healing demonstrated that titanium implants with the modified SLA surface can achieve and maintain successful tissue integration over a period of at least 6 months. The ISQ method seems feasible to monitor implant stability during the initial wound-healing period.

Outcome evaluation of early placed maxillary anterior single-tooth implants using objective esthetic criteria: a cross-sectional, retrospective study in 45 patients with a 2- to 4-year follow-up using pink and white esthetic scores

BACKGROUND: To validate the concept of early implant placement for use in the esthetically sensitive anterior maxilla, clinical trials should ideally include objective esthetic criteria when assessing outcome parameters. METHODS: In this cross-sectional, retrospective 2- to 4-year study involving 45 patients treated with maxillary anterior single-tooth implants according to the concept of early implant placement, a novel comprehensive index, comprising pink esthetic score and white esthetic score (PES/WES; the highest possible combined score is 20), was applied for the objective esthetic outcome assessment of anterior single-tooth implants. RESULTS: All 45 anterior maxillary single-tooth implants fulfilled strict success criteria for dental implants with regard to osseointegration, including the absence of peri-implant radiolucency, implant mobility, suppuration, and pain. The mean total PES/WES was 14.7 +/- 1.18 (range: 11 to 18). The mean total PES of 7.8 +/- 0.88 (range: 6 to 9) documents favorable overall peri-implant soft tissue conditions. The two PES variables facial mucosa curvature (1.9 +/- 0.29) and facial mucosa level (1.8 +/- 0.42) had the highest mean values, whereas the combination variable root convexity/soft tissue color and texture (1.2 +/- 0.53) proved to be the most difficult to fully satisfy. Mean scores were 1.6 +/- 0.5 for the mesial papilla and 1.3 +/- 0.5 for the distal papilla. A mean value of 6.9 +/- 1.47 (range: 4 to 10) was calculated for WES. CONCLUSIONS: This study demonstrated that anterior maxillary single-tooth replacement, according to the concept of early implant placement, is a successful and predictable treatment modality, in general, and from an esthetic point of view, in particular. The suitability of the PES/WES index for the objective outcome assessment of the esthetic dimension of anterior single-tooth implants was confirmed. However, prospective clinical trials are needed to further validate and refine this index.

Clinical and esthetic outcomes of implants placed in postextraction sites

PURPOSE: The aim of this review was to evaluate the clinical outcomes for the different time points of implant placement following tooth extraction. MATERIALS AND METHODS: A PubMed search and a hand search of selected journals were performed to identify clinical studies published in English that reported on outcomes of implants in postextraction sites. Only studies that included 10 or more patients were accepted. For implant success/survival outcomes, only studies with a mean follow-up period of at least 12 months from the time of implant placement were included. The following outcomes were identified: (1) change in peri-implant defect dimension, (2) implant survival and success, and (3) esthetic outcomes. RESULTS AND CONCLUSIONS: Of 1,107 abstracts and 170 full-text articles considered, 91 studies met the inclusion criteria for this review. Bone augmentation procedures are effective in promoting bone fill and defect resolution at implants in postextraction sites, and are more successful with immediate (type 1) and early placement (type 2 and type 3) than with late placement (type 4). The majority of studies reported survival rates of over 95%. Similar survival rates were observed for immediate (type 1) and early (type 2) placement. Recession of the facial mucosal margin is common with immediate (type 1) placement. Risk indicators included a thin tissue biotype, a facial malposition of the implant, and a thin or damaged facial bone wall. Early implant placement (type 2 and type 3) is associated with a lower frequency of mucosal recession compared to immediate placement (type 1).

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).

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.