Oral rehabilitation with implant-supported fixed partial dentures in periodontitis-susceptible subjects. A 5-year prospective study

BACKGROUND: Comparatively few studies with at least 5 years of follow-up are available that describe the use of implants in prosthetic rehabilitation of partially edentulous patients. Randomized, controlled clinical studies that evaluated the effect of different surface designs of screw-shaped implants on the outcome of treatment are also sparse. OBJECTIVE: To determine, in a prospective randomized, controlled clinical trial, the outcome of restorative therapy in periodontitis-susceptible patients who, following basic periodontal therapy, had been restored with implants with either a machined- or a rough-surface topography. MATERIAL AND METHODS: Fifty-one subjects (mean age, 59.5 years), 20 males and 31 females who, following treatment of moderate-to-advanced chronic periodontitis, required implant therapy for prosthetic rehabilitation were recruited. Seventeen of the patients were current smokers. Following the active treatment, all subjects were included in an individually designed maintenance program. A total of 56 fixed partial dentures (FPDs) and a total of 149 screw-shaped, and self-tapping implants (Astra Tech implants) -- 83 in the maxilla and 66 in the mandible -- were installed in a two-stage procedure. Each patient received a minimum of two implants and by randomization every second implant that was installed had been designed with a machined surface and the remaining with a roughened Tioblast surface. Abutment connection was performed 3-6 months after implant installation. Clinical and radiographical examinations were performed following FPD connection and once a year during a 5-year follow-up period. The analysis of peri-implant bone-level alterations was performed on subject, FPD and implant levels. RESULTS: Four patients and four FPDs were lost to the 5 years of monitoring. One implant (machined surface) did not properly integrate (early failure), and was removed at the time of abutment connection. Three implants were lost during function and a further eight implants could not be accounted for at the 5-year follow-up examination. The overall failure rate at 5 years was 5.9% (subject level), 5.3% (FPD level) and 2.7% (implant level). Radiographic signs of loss of osseointegration were not found at any of the implants during the 5-year observation period. During the first year in function there was on average 0.33 (SD, 0.61) mm loss of peri-implant marginal bone on the subject and FPD levels and 0.31 (0.81) mm on the implant level. During the subsequent 4 years, the peri-implant bone-level alterations were small. The calculated annual change in peri-implant bone level was -0.02 (0.15) on subject and FPD levels and -0.03 (0.20) on the implant level. Thus, the mean total bone-level change over the 5-year interval amounted to 0.41 mm on all three levels of analysis. In the interval between baseline and 5 years, the machined and the Tioblast implants lost on average 0.33 and 0.48 mm, respectively (p>0.05). CONCLUSION: The present randomized, controlled clinical trial that included partially edentulous periodontitis-susceptible subjects demonstrated that bone loss (i) during the first year of function as well as annually thereafter was small and (ii) did not vary between implants with machined- or rough-surface designs.     

Implant-supported fixed prostheses in the edentulous maxilla: 8-year prospective results

Objective: The purpose of this prospective study was to evaluate the long‐term survival and success rates of implants and screw‐retained, full‐arch prostheses placed in edentulous maxillae over 8 years of function. Materials and methods: A total of 106 Astra Tech implants were placed in the maxillae of 17 edentulous patients in a one‐stage surgical approach. After a healing period of 6 months, the patients received fixed screw‐retained bridges. Follow‐up visits, including clinical and radiographic examinations, were performed after 6 months and at yearly intervals. Implant survival, implant success, and marginal bone‐level changes were defined as the primary outcome variables. The secondary aims were to report periodontal pathogens at 5 years' follow‐up and patients' satisfaction at the 8‐year follow‐up. Results: The overall observation time was 8 years. One patient died during the study and one implant failed during the healing period, yielding an 8‐year cumulative implant survival rate of 99%. The prosthetic survival rate was 100%. The mean crestal bone loss amounted to 0.3 ± 0.72 mm. Patients' subjective evaluations demonstrated an overall high level of satisfaction. In all cases, except for one, microbiologic probing of the peri‐implant sulcus after 5 years showed no higher incidence of periodontal pathogens. Conclusions: Screw‐retained, full‐arch restorations on six implants in an edentulous maxilla are a predictable and highly successful treatment concept as observed throughout this study with an observation period of 8 years of function, in particular with respect to low crestal bone loss and high patient satisfaction. To cite this article:
Mertens C, Steveling HG. Implant‐supported fixed prostheses in the edentulous maxilla: 8‐year prospective results.
Clin. Oral Impl. Res. 22 , 2011; 464–472
doi: 10.1111/j.1600‐0501.2010.02028.x     

Bone level changes around axial and tilted implants in full-arch fixed immediate restorations. Interim results of a prospective study

Purpose: The aim of this prospective study was to assess clinical outcomes and peri‐implant bone level changes around tilted and axial implants supporting full‐arch fixed immediate rehabilitations up to 60 months of loading. Material and Methods: Forty‐seven patients (22 women and 25 men) were included in the study. Each patient received a full‐arch fixed bridge supported by two axial and two distal tilted implants. Loading was applied within 48 hours of surgery. Patients were scheduled for follow‐up at 6, 12, 18, 24 months, and annually up to 5 years. At each follow‐up, plaque level and bleeding scores were assessed and radiographic evaluation of marginal bone level change was performed. Periapical radiographs were taken using a paralleling technique, and subsequently scanned at 600 dpi. An image analysis software was used to assess bone level. Results: A total of 33 mandibles and 16 maxillae were rehabilitated (two patients received a fixed prosthesis in both arches). One hundred ninety‐six Nobel Biocare implants of 4 mm diameter were placed. The mean follow‐up duration was 52.8 months (range 30–66 months) in the mandible, and 33.8 months (range 22–40 months) in the maxilla. All subjects attended the scheduled follow‐up visits. No implant was lost. No significant difference in marginal bone loss was found between axial and tilted implants in both jaws, at each follow‐up. No significant difference in bone loss was found between mandible and maxilla, for both axial and tilted implants at each comparable time frame, although slightly higher mean values were always found for the mandible. Conclusion: The use of tilted implants in the immediate rehabilitation of fully edentulous jaws is safe and is not associated to a higher marginal bone loss as compared to axially placed implants.     

A 5-year prospective clinical and radiographic study of non-submerged dental implants

Osseointegrated implants as anchors for various prosthetic reconstructions have become a predictable treatment alternative. It was expected that implants required submucosal placement during the healing period for successful tissue integration. However, it has been demonstrated that healing and long-term health of implants could be achieved with equal predictability in a 1-stage, non-submerged approach. This prospective 5-year study not only calculates implant success by life table analysis, but also evaluates the correlation between observed bone level changes with clinical parameters as measured by suppuration, plaque indices, bleeding indices, probing depth, attachment level and mobility. A total of 112 ITI dental implants were inserted in different areas of the jaws. Clinical and radiographic parameters were evaluated annually for 5 years, whereas a portion of the study group for which 6-year evaluations were available were included in the life-table analysis. The overall success rate after 5 years in service was 99.1%, while after 6 years it was reduced to 95.5% due to the fracture of 3 implants in 1 patient. The mean crestal bone loss experienced during the first year was 0.6 mm followed by an annual yearly loss of approximately 0.05 mm. No significant differences could be found between the amount of bone loss measured at each of the yearly follow-up visits. This suggests that statistically the followed implants did not show any radiographically measurable bone loss following the initial period of bone loss associated with implant placement and osseointegration. Low levels of correlation between the individual and cumulative clinical parameters with radiographically measured bone loss suggests that these parameters are of limited clinical value in assessing and predicting future peri-implant bone loss.     

Long-term results and survival rate of implants treated with guided bone regeneration: a 5-year case series prospective study

One of the key factors for attaining osseointegration is the presence of an adequate osseous volume. In patients with inadequate osseous width or height, a bone augmentation using the guided bone regeneration (GBR) concept may be applied either with a simultaneous or a staged approach. The aim of this multicenter prospective case series study was to evaluate the efficacy and predictability of the GBR technique (simultaneous approach) in patients with peri-implant osseous defects, both dehiscences and fenestrations. Results 5 years post-treatment (survival rates and marginal bone level) were assessed. A total of 19 consecutive patients with 26 peri-implant osseous defects (20 dehiscences and six fenestrations) were treated during the period from September 1992 to June 1993 with a simultaneous GBR approach using non-resorbable membranes combined with autogenous bone grafts or decalcified freeze-dried bone allograft. The mean osseous augmentation was 94.8%. Marginal bone levels at re-entry and 5 years after surgery were calculated from standardized periapical radiographs. One implant was lost 3 months after loading. Thus, the cumulative survival rate was 96.1% after 5 years. The mean marginal bone level after 5 years was 2.03 mm (SD=+/-0.5), without a difference between mesial and distal sites. This study demonstrates that implants with peri-implant defects that are treated with GBR had similar survival rates and crestal bone levels compared with implants in native bone.     

Evaluation of aesthetics of implant-supported single-tooth replacements using different bone augmentation procedures: a prospective randomized clinical study

OBJECTIVES: The aim of this study was to evaluate the aesthetics of implant-supported single-tooth replacements using different augmentation procedures in a prospective study with the use of an objective rating index and with a subjective patient questionnaire, and to compare the results with each other. MATERIAL AND METHODS: Ninety-three patients with a single-tooth gap in the anterior zone of the maxilla were selected for the study. All patients had a local bone defect that needed augmentation before placement of an endosseous implant with sufficient initial stability. Aesthetics of the implant-supported crown and adjacent mucosa was rated by a prosthodontist 1 year after placement of the porcelain crown. Aesthetics was rated using the Implant Crown Aesthetic Index. A subjective appreciation of the final result was assessed with a patient questionnaire. RESULTS: The Implant Crown Aesthetic Index reveals a mean overall score of 4.8, with an acceptable result in 66% of the cases. Results of the satisfaction questionnaire reveal a mean overall score of 8.5 with an acceptable result in 100% of the cases. There is no correlation between results of the Index and the questionnaire for the overall and the crown score. The patients' opinion and the professionals' opinion about the peri-implant mucosa do show a significant correlation. CONCLUSIONS: The peri-implant mucosa is rated as less satisfactory than the implant-supported crown by both the dental professional and patients. The dental professional was less satisfied with respect to the total result and results of the crown than the patients.     

Immediate loading of single-tooth ITI implants in the anterior maxilla: a prospective 5-year pilot study

The aim of the present study was to evaluate the success rate of immediately loaded single-tooth ITI solid plasma-sprayed (TPS) implants in the maxilla. Eight implants were loaded immediately after placement in eight different patients, and were followed for five years. Temporary acrylic resin restorations, which were fabricated from impressions that were taken immediately after implant placement, were connected one week later. These temporary restorations were adjusted in order to avoid any direct occlusive contacts. After six months, the provisional crowns were replaced by definitive ceramic crowns. Regular follow-ups were performed during the investigation period. No implants were lost, and the mean marginal bone level for the eight implants increased by 0.53 mm (range - 0.83 to + 1.54 mm) from placement to the final examination. Only minor complications were noted, and overall patient satisfaction was high.     

Evaluation of single-tooth restorations on ITI dental implants. A prospective study of 29 patients

From January 1992 to March 1997, a total of 30 ITI hollow cylinder implants were installed to replace lost single maxillary incisor teeth. Conical abutments with cemented all-ceramic crowns were used in 10 cases and the Octa-abutment with screw-retained metallo-ceramic crowns in 19 cases. One implant failed due to postoperative infection, and was extracted a month after installation. After a mean observation time of 3.4 years, the cumulative success rate is 96.7%. Only minor bone loss has occurred around the implants, and there have been no other complications to date. The implant system fulfills the requirements for good function and esthetics.     

Osteotome sinus floor elevation technique without grafting material: 3-year results of a prospective pilot study

Objective: In a prospective pilot study, short≤10 mm ITI-SLA implants were placed in the resorbed posterior maxilla by means of an osteotome sinus floor elevation (OSFE) procedure without grafting material. This paper presents 3-year data assessing bone-level changes around implants.
Material and methods: Twenty-five implants were placed in 17 patients to rehabilitate 16 molar and nine premolar sites. The mean residual bone height (RBH) was 5.4 ± 2.3 mm. A healing period of 3–4 months was allowed before abutment tightening. Most implants (21/25) were 10 mm long, and the others were 8 and 6 mm long. At the 3-year control, endo-sinus bone gain, implant length protruding into the sinus and crestal bone loss (CBL) were measured on periapical radiographs.
Results: All implants fulfilled the survival criteria. Despite the absence of grafting material, implants were embedded into newly formed bone tissue. All implants gained endo-sinus bone; the mean gained bone was 3.1 ± 1.5 mm. The residual protrusion length decreased from 4.9 ± 2.1 to 1.8 ± 2.1 mm. CBL was 0.9 ± 0.8 mm.
Conclusions: This study confirms that the OSFE procedure without grafting material is sufficient to create bone beyond the natural limit of the sinus. On the mid-term of 3 years, the technique was found to be predictable in the posterior maxilla when the RBH is limited. Implants gained endo-sinus bone despite the lack of grafting material. Bone gain was still improving over the first-year control. No shrinkage of the augmented area was observed.     

Clinical outcome of Screw Vent implants. A 7-year prospective follow-up study

The clinical results of 85 Screw Vent implants are described with respect to 7-year success, including radiographically detectable bone loss, survival and prosthetic quality. The 1-year results of the same material have been reported previously (De Bruyn et al. 1992). Implants were considered as successful when they were meeting with the success criteria proposed by the European Academy for Periodontology. From the 85 implants originally installed, 16 failed during the 7-year interval (18.8%), 6 were unaccounted for (7%), 21 (24.7%) did not meet the success criteria yet survived and 42 implants (49.4%) were successful. The success rate was 65.2% for the mandibular and 43.5% for the maxillary implants. Implant failures were irrespective of implant length, smoking habits, prosthetic quality or oral hygiene level. From 24 patients with a corresponding number of 60 implants, radiographs were available for bone loss analysis. The mean bone loss after 7 years was 2.92 mm (range -0.5 to 6.3) 18 out of 60 examined implants (30%) showed unacceptable radiological bone loss beyond the critical value of 2.7 mm. Implant material analysis and histomorphometric analysis of a retrieved implant are discussed. In the present clinical study, the Screw Vent implant system does not meet the success criteria proposed by the European Academy for Periodontology. The ongoing bone loss increases the risk for future implant failures and peri-implant disease.     

On cutting torque measurements during implant placement: a 3-year clinical prospective study

Background: Evaluation of jaw bone quality at implant placement is mainly based on preoperative radiographic assessments and subjective hand registrations during implant site preparation. An objective technique with cutting torque measurements has been introduced, presenting an objective bone quality or bone hardness value of individual implant sites. Purpose: The purpose of this study was to evaluate cutting torque measurements during implant placement and to compare these values in different regions in mandibles and maxillae. The objective was to identify implants at risk for failing at implant placement. Material and Methods: Cutting torque measurements were performed during placement of Mk II self-tapping implants (Brånemark System ^TM) in 105 patients, comprising 72 edentulous (40 maxillae) and 34 partially edentulous (22 maxillae) jaws. A total of 523 implants were inserted, of which 420 were of the Mk II design and of which 412 were subjected to cutting torque measurements. Statistical analyses were performed by comparing cutting torque values of maxillae and mandibles and of different jaw regions. Cutting torque values were also correlated with radiographically and clinically assessed bone quality scores. Patients were followed clinically for a minimum of 3 years. Results: A statistically significant difference in cutting torque values of maxillae and mandibles was seen, although not when comparing anterior and posterior regions within the same jaws or of different jaws. Significant correlations were found between values of cutting torque and bone quality. The majority of failures were seen in bone of medium to high density, whereas implants inserted in bone of poor density presented a better outcome, perhaps due to an adapted surgical protocol and an extended healing period. The overall implant survival rate at 3 years was 95%, and when analyzing different jaw categories, survival rates of 92.0% and 99.4% were seen for edentulous maxillae and mandibles, respectively. The corresponding figures for partially edentulous jaws were 95.4% and 97.6%. Conclusion: It was not possible to identify sites at risk for future implant losses or to determine a lower limit value of cutting torque in order to achieve successful implant integration.     

Implant-supported mandibular overdentures: a cross-sectional study

Objective: The aim of this cross‐sectional study was to determine the clinical outcome and patient satisfaction in subjects treated with mandibular overdentures supported by two implants. Material and methods: One hundred and fifty‐nine patients, who received restorative therapy in the edentulous mandible consisting of a bar‐retained overdenture supported by two osseointegrated implants in a private clinic in Italy, were recalled for a clinical and radiographic examination. One hundred and forty‐one subjects with 280 implants attended the examination. The average follow‐up time was 3.9 years. The radiographic examination included assessments of the distance between the implant margin and the most coronal position of bone‐to‐implant contact at the mesial and distal aspects of each implant. A questionnaire regarding comfort, satisfaction with the treatment, aesthetics, speaking capacity and efficiency in chewing was obtained from each subject. Biological and technical complications were recorded and the number of visits due to complications between the delivery of the prostheses and the re‐examination was determined. Results: The results from the examination revealed that the number of lost implants was small and the average marginal bone level around the implants was 0.67 mm apical of the implant margin. The most frequently observed complication was hyperplasia of the mucosal tissue under the bar construction. Few patients experienced loosening of retention. The vast majority of patients reported to be satisfied in relation to the restorative therapy from both functional and aesthetic points of view. Conclusion: Patients with edentulous mandibles may be successfully rehabilitated by means of two implants supporting a bar‐retained overdenture. To cite this article:
Bressan E, Tomasi C, Stellini E, Sivolella S, Favero G, Berglundh T. Implant‐supported mandibular overdentures: a cross‐sectional study.
Clin. Oral Impl. Res. 23 , 2012; 814–819.
doi: 10.1111/j.1600‐0501.2011.02225.x