A study of 589 consecutive implants supporting complete fixed prostheses. Part I: Periodontal aspects.

Ninety-one consecutive edentulous patients who had been treated by means of fixed prostheses (n = 103) supported by Br?nemark implants (n = 589) were examined. Eighteen fixtures (3%) failed to integrate. After a mean loading time of 32 (range 6 to 80) and 38 months (range 5 to 83) for fixtures in the maxilla and mandible, respectively, an additional 12 fixtures lost integration. The cumulative failure rate for individual fixtures after 6 years was 8.4% and 5% for maxillae and mandibles, respectively. Only one patient had to revert to complete dentures. For fixtures in the maxillae, the mean marginal bone loss was 0.7, 0.1, and 0.2 mm for each of the first 3 years of loading, respectively; for fixtures in mandibles, the corresponding values were 0.7, 0.2, and 0.1 mm. The loss in marginal bone height was equal in both jaws and was not related to bleeding on probing or to the preoperative resorption anatomy.     

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.     

Soft Tissue Conditions and Marginal Bone Changes around Immediately Loaded Implants Inserted in Edentate Jaws Following Computer Guided Treatment Planning and Flapless Surgery: A ≥1‐Year Clinical Follow‐Up Study

Background: Evaluation of the clinical conditions following computer guided treatment planning and flapless surgery is still limited. Objectives: The objective was to evaluate the soft tissue conditions and marginal bone changes after 1 year of function around immediately loaded implants inserted in edentate jaws following computer guided treatment planning and flapless surgery. Material and Methods: Twenty‐nine edentate jaws (19 maxillae, 10 mandibles) treated with 165 implants using the Teeth‐in‐an‐Hour? protocol were included. In these patients, peri‐implant soft tissue conditions and radiographic marginal bone changes were evaluated after ≥1 year of functional loading (mean: 19 months). Results: The mean probing depth at case level was 2.6 mm (SD: 0.6). Bleeding on probing was recorded as a mean of 81.9% (SD: 23.0). Plaque index showed a wide range of 0–100%. The mean marginal bone change of measured sites evaluated on intraoral radiographs was ?1.2 mm (SD: 1.4). A marginal bone loss more than 1.5 mm or 2.0 mm was observed in 42% and 27% of the measured sites, respectively. A pressure‐like‐ulcer was found in 9 cases. Implants with marginal bone loss of >1.5 mm were more frequently observed in cases with an ulcer than cases where no ulcer was found. Conclusion: Although the mean marginal bone loss after function in the present study was within the range of other reports presenting mean bone loss data after immediate implant loading, our patients showed a wide range of bone loss with several sites, where the bone loss was greater than the commonly used successful level (>1.5 mm).     

Long-term evaluation of 282 implants in maxillary and mandibular molar positions: a prospective study.

BACKGROUND: Placement of implants into molar positions presents diagnostic, surgical and prosthetic challenges. There are few reported studies for implants placed into molar positions. The purpose of this prospective longitudinal study is to report long-term clinical outcomes for 282 implants placed into molar positions. METHODS: Two-hundred-twelve patients received 282 implants. Implant size, location, jaw shape, and bone quality were recorded for all implants placed into molar positions. Seventy implants were inserted in maxillae and 212 in mandibles. Marginal bone level changes in maxillae and mandibles were measured from non-standardized periapical radiographs taken at abutment connection and an average follow-up of 3.9 years. Mesial-distal implant measurements were made from the top of the implant cylinder to the first point of bone to implant contact. In mandibles, 39 implants were used for single molar replacements, 67 implants were placed into excellent bone quality (type I) and 113 were in good bone quality (type 11); 145 implants were placed into bone with moderate bone resorption (type B); 166 implants were placed in first molar positions and 46 in second molar sites. RESULTS: At 6 years the cumulative success rate (CSR) for mandibular implants is 91.5%, and the success rate from the 2 to 3 year follow-up is 100%. Of the 70 implants placed in maxillae, 16 replaced single molars. Thirty-two implants were placed in jaw shape B with type 2-bone quality. For maxillary implants, the 6-year CSR was 82.9% and the success rate remained steady at 100% after the 2 to 3 year follow-up. For maxillary implants, at abutment connection the average marginal bone level was 1.67 mm, while at follow-up it was 1.98 mm. These differences were statistically significant (P = 0.04), but are not considered to be clinically significant. For mandibular implants, at abutment connection the mean marginal bone level as measured from radiographs was 2.11 mm, and at follow-up was 2.02 mm. This slight gain in bone level was not statistically significant and is not considered to be clinically significant. CONCLUSIONS: Results of this prospective longitudinal study of implants placed into molar positions indicates favorable clinical outcomes. These CSR rates (91.5% mandibles, 82.9% maxillae) are less than what has been reported for implants placed into mandibular and maxillary anterior segments. Differences in outcomes between anterior and posterior locations may be related to bone quality and quantity.     

Early failures in 4,641 consecutively placed Br?nemark dental implants: a study from stage 1 surgery to the connection of completed prostheses.

This study comprised 4,641 Br?nemark dental implants, which were retrospectively followed from stage 1 surgery to completion of the prosthetic restorations. The implants were placed during a 3-year period (1986 to 1988) in 943 jaws, representing 889 patients with complete and partial edentulism. The jaw and sex distribution revealed a predominance of mandibles (564/943) and females (534/943). The mean age of the patients was 57.5 years (range 13 to 88 years) at implant placement. Only 69 (1.5%) fixtures failed to integrate, and most losses were seen in completely edentulous maxillae (46/69), in which the jaw bone exhibited soft quality and severe resorption. A preponderance of failures could also be seen among the shortest fixtures (7 mm). A majority of the mobile implants were recorded at the abutment connection (stage 2) operation (48/69).     

Brånemark System Wide Platform implants for single molar replacement: clinical evaluation of prospective and retrospective materials

Background: The use of oral implants for single tooth replacement has become a predictable treatment modality. As single tooth loss is most common in posterior areas of the jaws, the use of the protocol is of specific interest in those regions. New implant designs aimed at this purpose have also been introduced. Purpose: The aim of the study was to present the outcomes for wide diameter implant treatment when being used in posterior areas of the jaws. Materials and Methods: This paper presents the 3‐year results of a prospective multicenter study (three clinics; n = 38 implants) and the 1‐year results from a retrospective multicenter study (two clinics; n = 20 implants) on wide diameter implants for single molar replacement. Based on the hypothesis that dense bone in posterior mandibles would benefit from careful surgery and longer remodeling time, the influences of surgical technique and healing time on implant success and bone resorption were particularly addressed. Results: The outcome demonstrated a good predictability for Brånemark System® Wide Platform implants, at least short term, when used as single molar support (prospective group cumulative success rate [CSR] = 92% after 3 years; retrospective group CSR = 95% after 1 year). The increased mechanical strength of the wide platform implant/abutment complex also turned out to be important for mechanical stability. Conclusions: The study indicated that it was important to carefully perform surgery in posterior mandibles in order to preserve and optimally use the existing dense bone. It was suggested that from bone healing and remodeling aspects, posterior mandibles may be more demanding to handle than corresponding areas of maxillae.     

Radiographic measurements of alveolar bone loss in the rat

A new method to evaluate alveolar bone loss in rodents is described. The palatal and lingual halves of maxillae and mandibles were radiographed. On enlarged positive prints, 5 vertical distances were drawn at defined sites from the cemento-enamel junction to points revealing fully intact bone structure. These were either located on the alveolar crest or at the depth of intrabony defects. These distances were recorded with a trace-reading pen coupled to a computer. Results were expressed in mm for each site separately and totals (left plus right values) for either maxillae or mandibles were calculated. This technique was compared to other methods for evaluating alveolar bone loss, using the jaws of rats subjected to a gnotobiotic regime in which the degree of bone loss was low. It was demonstrated that the measurement of vertical distances based on radiography by which also intrabony defects were defined was accurate, reproducible and more sensitive than other means of evaluating bone loss.     

Clinical outcomes of keratinized mucosa augmentation in jaws reconstructed with fibula or iliac bone flaps

This prospective study was undertaken to evaluate the treatment outcomes of keratinized mucosa augmentation (KMA) on the buccal and palatal/lingual sides of implants in jaws reconstructed after oncological surgery. Forty-two implants in 12 patients whose jaws had been reconstructed with a fibula or iliac bone flap were included. KMA was performed at 3 months after implant placement; this included an apically displaced partial-thickness flap and a free gingival graft (FGG) around the implants to increase the keratinized mucosa width (KMW). Patients were followed up for at least 6 months post-surgery. KMW, shrinkage, and patient pain and discomfort measured on a visual analogue scale were analysed. A histological analysis was performed of tissue epithelium from two patients. The results showed that KMW was >2 mm on both the buccal and palatal/lingual sides during follow-up. Before surgery, histological analysis showed epithelium with no epithelial spikes; normal keratinized epithelial spikes were observed at 8 weeks after KMA. Greater KMW was observed around implants in reconstructed maxillae than around those in reconstructed mandibles (P < 0.001). Patients felt more pain at the donor site than at the recipient site during the first 3 days post-surgery. KMA with FGG was predictable in reconstructed jaws and may help maintain the long-term stability of implants.     

A study of 589 consecutive implants supporting complete fixed prostheses. Part II: Prosthetic aspects

In 91 consecutive edentulous patients, 103 jaws were treated with complete fixed prostheses supported by Br?nemark Implants (n = 589). As a result of fixture loss in each of two patients (two jaws), an overdenture instead of a fixed prosthesis was installed. For one patient (two jaws), data were not available after abutment connection. At the end of the seventh year, the cumulative failure rates for the remaining 99 prostheses reached 4.9% for mandibles and 10.1% for maxillae. After loading, 12 fixtures showed signs of nonintegration, but only one patient had to revert to complete dentures. Neither the fixture location nor the cantilever length revealed a significant difference in marginal bone loss around the supporting fixtures. Patients with fixture-supported fixed prostheses in both jaws showed significantly more marginal bone loss than did those with only one fixed prosthesis opposed by either natural dentition (50%) or a complete denture (50%). Component complications were limited to fixture fracture (3/564), abutment screw fracture (5/564), and gold screw fracture (7/564). The predictability of Br?nemark implants in the treatment of completely edentulous jaws is confirmed.     

Use of 5-mm-diameter implants: Periotest values related to a clinical and radiographic evaluation.

A modified design of the original Brånemark implant consisting of a cp. Titanium 5.0-mm-diameter self-tapping implant threaded up to the marginal platform has been proposed for specific indications. From February 1992 to November 1995, a total of 185 machined screw implants (Nobel Biocare, Gothenburg, Sweden) were installed in 45 patients to withstand 58 prostheses. Of these, 91 were 3.75mm diameter and 94 were 5.0mm wide. Most of the implants were placed in type B and C bone quantity and type 2 and 3 bone quality. A retrospective evaluation with regard to indications, marginal bone remodelling, Periotest® values (ID) and survival rate is presented. PTv and radiographic measurements were made at abutment connection and repeated 3, 6 and 12 months later and thereafter every year. The follow-up ranged from 16 to 55 months (mean 32.9 months) post-loading. Three patients with 8 5.0mm implants dropped-out of the study at different stages. Out of the wide implants, 1 was expelled during the healing period; 3 were found mobile at the abutment connection; 1 lost its osseointegration suddenly after 2 years of function; 4 belonging to 1 patient did not meet the success criteria due to continuous marginal bone loss. The cumulative success rate of 5.0mm implants (CSR) after 1 year of function was 97.2% for upper jaws and 88.4% in mandibles, whereas the CSR in maxilla after 48 months was 97.2% and 83.4% in mandibles. The obtained PTv from 5.0mm-wide fixtures in maxilla and mandibles were respectively 1.1 and 0.6 units lower than those obtained PTv for 3.75mm-diameter implants in the same patients. The hypothesis that there are differences in the damping capacity of the bone surrounding a 5.0mm-wide implant compared to the 3.75mm-diameter implant is supported by the PTv results.     

A Retrospective Study on 287 Implants Installed in Resorbed Maxillae Grafted with Fresh Frozen Allogenous Bone

Background: Several studies have been performed to evaluate the clinical outcome of implants inserted into maxillae grafted with autogenous bone but few reports have focused on maxillae grafted with fresh‐frozen allogenous bone (FFAB). Purpose: The purpose of this study is to retrospectively evaluate the clinical outcome of implants installed in resorbed maxillae augmented with FFAB. Materials and Methods: A total of 69 patients whom had been treated with FFAB grafts to their maxillae and implant placement 4 to 6 months later were retrospectively evaluated. Edentulism was total and partial in 22 and 47 cases, respectively. A total of 287 implants of various systems had been used. A life table analysis was performed. Marginal bone loss was calculated in radiographs. Results: Five of the 287 implants were lost, giving a survival rate (SVR) of 98.3% over a mean follow‐up time of 26 months. The marginal bone resorption at the implants was 1.68 mm (SD = 0.44) after 1 year and 1.85 mm (SD = 0.98) after 4 years. The cumulative success rate based on defined criteria was 96% in the first year but decreased to 40% at 4 years because of marginal bone loss. The Kaplan–Meier algorithm demonstrated a better outcome for female patients, removable dentures, and total edentulism. No differences were detected among diameters, lengths, and implant site. Conclusion: Implants placed in FFAB showed a high SVR similar to that reported in previous studies on maxillae grafted with autogenous iliac crest bone. Although our data point to more marginal bone loss in partially edentulous patients and for fixed prosthetic restorations, the use of FFAB for reconstruction of the atrophic jaw prior to implant placement can be considered as a reliable alternative to autogenous bone.     

Use of 5‐mm‐diameter implants: Periotest® values related to a clinical and radiographic evaluation

A modified design of the original Brånemark implant consisting of a cp. Titanium 5.0‐mm‐diameter self‐tapping implant threaded up to the marginal platform has been proposed for specific indications. From February 1992 to November 1995, a total of 185 machined screw implants (Nobel Biocare, Gothenburg, Sweden) were installed in 45 patients to withstand 58 prostheses. Of these, 91 were 3.75mm diameter and 94 were 5.0mm wide. Most of the implants were placed in type B and C bone quantity and type 2 and 3 bone quality. A retrospective evaluation with regard to indications, marginal bone remodelling, Periotest® values (ID) and survival rate is presented. PTv and radiographic measurements were made at abutment connection and repeated 3, 6 and 12 months later and thereafter every year. The follow‐up ranged from 16 to 55 months (mean 32.9 months) post‐loading. Three patients with 8 5.0mm implants dropped‐out of the study at different stages. Out of the wide implants, 1 was expelled during the healing period; 3 were found mobile at the abutment connection; 1 lost its osseointegration suddenly after 2 years of function; 4 belonging to 1 patient did not meet the success criteria due to continuous marginal bone loss. The cumulative success rate of 5.0mm implants (CSR) after 1 year of function was 97.2% for upper jaws and 88.4% in mandibles, whereas the CSR in maxilla after 48 months was 97.2% and 83.4% in mandibles. The obtained PTv from 5.0mm‐wide fixtures in maxilla and mandibles were respectively 1.1 and 0.6 units lower than those obtained PTv for 3.75mm‐diameter implants in the same patients. The hypothesis that there are differences in the damping capacity of the bone surrounding a 5.0mm‐wide implant compared to the 3.75mm‐diameter implant is supported by the PTv results.     

Clinical report on the success of 47 consecutively placed Core-Vent implants followed from 3 months to 4 years

This report presents the clinical outcome of 47 consecutively placed Core-Vent implants inserted in 35 patients followed for 2 to 4 years by clinical and 3 to 48 months by radiographic examination. The implants were used in mandibles and maxillae to support single crowns, overdentures, and fixed prostheses splinted to natural teeth as recommended by the manufacturer. Of the 47 implants, 43 could be examined. A total of 11 implants was removed, nine because of progressive vertical bone loss and two because of fractures. The vertical bone loss was calculated for the 32 remaining implants. Twenty-eight implants demonstrated a bone loss of more than 2 mm and 16 showed a loss of more than one-third of the implant height. According to the criteria proposed by Schnitman and Shulman in 1979, the total success rate was 37.2%. When using the criteria suggested by Albrektsson et al in 1986, the total success rate was calculated to be 9.3%.     

A new self-tapping Br?nemark implant: clinical and radiographic evaluation.

A new self-tapping Br?nemark implant designed for denser bone qualities was evaluated with regard to insertion technique, complications, marginal bone remodeling, and survival rate. Thirty patients, representing 21 mandibles and 9 maxillae, participated in the study. In each patient both standard and self-tapping implants were placed, and a total of 179 implants, 88 self-tapping and 91 standard, were inserted. Thirteen of 62 mandibular self-tapping implants reached their correct positions only after using the screw tap or the cylinder wrench for manual insertion. No such problems were noted when using standard fixtures after bone pre-tapping. In the maxillae, neither of the two implant designs presented any problems. One standard and one self-tapping fixture failed to osseointegrate. Radiolucencies were seen in the bone around the apical portion of two fixtures, one of each design. The mean marginal bone resorption after 1 year of follow-up was 0.5 to 0.6 mm for the two fixture types.     

A comparative study of the clinical efficacy of Screw Vent irnnlants versus Brånemark fixtures, installed in a periodontal clinic

The clinical success of 85 Screw Vent® and 107 Bråemark® implants, consecutively installed in a private periodontal clinic under the same conditions and by the same operator, is compared. Mobile implants were removed and considered as failures. Intraoral radiographs were assessed for the presence of peri-implant radiolucencies and for analysis of bone loss after functional loading. 85 Screw Vent implants were installed in 31 patients. Of 23 implants installed in 9 mandibles, none failed after 16.8 (range 12–25) months of function. Of 62 Screw Vent implants installed in 23 maxillae, 6 failed at abutment connection, 1 failed after 2 months and 2 after 13 months of function. The absolute failure rate after 13.2 (range 6–24) months was 9162. Mean loss of bone was 1.47 mm (-l.O–+4) after 12 months of functional loading. 107 Brånemark fixtures were installed in 25 patients. Of 51 fixtures inserted in 12 mandibles, none failed; of 56 fixtures installed in 13 maxillae 1 failed before and 2 failed during abutment connection. The absolute failure is 3156. All remaining fixtures were immobile after loading. 13 fixtures were more than 6 months in function. Only short-term comparison between both systems is possible because the observation time is longer for the Screw Vent implants. In the 1st year, only 1 implant system was available to the periodontist. Short-term comparison reveals 11.3% versus 5.3% of cumulative failure after 6 months for the Screw Vent and Brånemark implants, respectively. The results indicate that clinical efficacy is as effectively obtained with Screw Vent as with Brånemark implants in the mandible. The outcome of treatment with Screw Vent implants in the maxilla seems less predictable.     

Asymmetry in periodontal bone loss of gnotobiotic Sprague-Dawley rats.

In five consecutive experiments involving 78 gnotobiotic rats, significant bone loss was seen in the maxillae of those mono-infected with strains of Porphyromonas gingivalis. No significant bone loss was seen in the mandibles, and when data from both jaws were combined, the significant loss in the maxillae was occasionally concealed. It is recommended, therefore, that the levels of maxillary and mandibular bone in rats be analysed separately. A possible lateral bias of periodontal bone level was investigated in the same rats. In a highly significant number of cases the right-hand side was more severely affected than the left. This asymmetry was found in both germ-free and infected rats, and consequently could not be ascribed to P. gingivalis infection. Asymmetry of bone loss may contribute to the total random variation in bone level in rats and should be accounted for in future studies of experimental periodontitis in this model.     

Provisional implants for anchoring removable interim prostheses in edentulous jaws: a clinical study

PURPOSE: The behavior of provisional implants in edentulous maxillae/mandibles used for anchoring removable interim overdentures was followed for the time of the intended healing of the definitive implants. MATERIALS AND METHODS: Twenty-eight edentulous arches (19 maxillae, 9 mandibles) were provided with 77 provisional implants (2 to 4 in maxillae; 2 or 3 in mandibles) for anchoring removable interim prostheses (overdentures). The provisional implants were to be maintained until final restoration (6 to 9 months in the maxilla and 3 months in the mandible). The loss rate of provisional implants and handling and behavior of the anchored overdenture were monitored until the definitive prosthetic restoration was placed. RESULTS: Twenty-three (29.8%) of the 77 provisional implants were lost prematurely. The loss rate of maxillary provisional implants (21/58; 36.2%) was significantly higher than that of mandibular implants (2/19; 10.5%) (P < .01). Determination of terminal stability (by means of the Periotest) of the provisional implants showed higher stability in the mandible (+3.8 +/- 2.3) than in the maxilla (+8.6 +/- 3.9) (P < .05). In obvious contrast to mandibular interim overdentures, handling of maxillary interim overdentures was found to improve significantly during the follow-up period (P < .01). DISCUSSION AND CONCLUSION: With both the low loss rate in the mandible and the higher loss rate seen in the maxilla, placement of provisional implants fulfills the requirements for initiating immediate prosthetic rehabilitation. The removable interim overdenture can be adequately stabilized and provides for added patient comfort and satisfaction as compared to a conventional complete denture. An important aspect of the continued use of provisional implants concerns the expectations placed in these implants by both clinician and patient, which are quite different than those for definitive implants.     

Front tooth replacement with Tübingen (Frialit®) implants: a radiographical evaluation

summary A total of 214 radiographs of 76 Tubingen implants placed in the anterior region of the maxillae of 56 patients were evaluated by two observers. The first radiographs were taken after implant placement (n = 76). The second set of radiographs were taken during months 13–23 (n =53), the third during the months 24–35 (n = 28), the fourth during months 36–47 (n = 15), the fifth during months 48–59 (n = 18) and the sixth during months 60–72 (n = 20). Only four radiographs were available after longer periods, namely the eight and the ten year of function. The two observers together classified the marginal bone height (mesial and distal) as 0 (no resorption) or 1–5 in steps of 2–5 mm resorption. A score of 1 represents marginal bone resorption less than 2–5 mm, 2 from 2–5 mm to 5 nun, 3 from 5 to 7–5 mm, 4 from 7–5 to 10 mm and 5 more than 10 mm loss of marginal bone height. Thirty-six implants scored marginal bone height of 0 or 1. Twenty-two implants scored not higher than 2. Eight implants scored bone loss up to 3, four up to 4 and one up to 5. Five implants were lost.     

Tilting of posterior mandibular and maxillary implants for improved prosthesis support

Rehabilitation of atrophied edentulous arches with endosseous implants in the posterior regions is often associated with anatomic problems such as jaw shape and location of the mental loop, mandibular canal, and maxillary sinuses. The purpose of this investigation was to modify the method for implant placement in the posterior part of the jaws to extend fixed implant-connected prostheses further distally, and to reduce the length of cantilevers in complete-arch prostheses without transpositioning the mandibular nerve or performing bone grafting in the maxilla. Forty-seven consecutive patients were treated with implants (25 patients/36 mandibular implants, 22 patients/30 maxillary implants) placed in tilted positions. They were followed a mean of 40 months (mandibles) and 53 months (maxillae). In the mandible, implants close to the mental foramina were tilted posteriorly approximately 25 to 35 degrees. In the maxilla, the posterior implants were placed close to and parallel with the sinus walls and were titled anteriorly/posteriorly approximately 30 to 35 degrees. Patients gained a mean distance of 6.5 mm of prosthesis support in the mandible and 9.3 mm in the maxilla, as a result of implant tilting. There were no implant failures in mandibles. The cumulative success rates in the maxilla at 5 years were 98% for tilted implants and 93% for non-tilted implants. Paresthesias of the mental nerve were observed on 4 sides during the first 2 to 3 weeks after implant placement. Analysis of the load distribution in one mandibular case showed no significant difference between tilted and the non-tilted implants, and the improved prosthesis support was confirmed. Satisfactory medium-term results concerning osseointegration and significant extension of prosthesis support show that the method can be recommended. This technique may allow for longer implants to be placed with improved bone anchorage.     

Short-term clinical results of Nobel Direct implants: a retrospective multicentre analysis

PURPOSE: The present retrospective clinical study was undertaken to evaluate the survival rate and marginal bone conditions around Nobel Direct one-piece implants. The purpose was also to compare the results with when these implants are used for immediate/early loading with implants allowed to heal before loading. MATERIAL AND METHODS: Forty-three consecutive patients previously treated with 117 Nobel Direct implants at four different centres were evaluated. The implants had been used in both jaws for treatment after loss of single and multiple teeth. Immediate/early loading (within 2 weeks) with a provisional crown/bridge was applied to 95 implants, while 22 implants healed unloaded for 6 weeks to 6 months before loading. Calculations of marginal bone loss were performed in radiographs taken at placement and after an average of 10.2 months (range 1-18 months) of loading. RESULTS: Six (5.1%) of the 117 implants were removed during the follow up. All failed implants belonged to the immediate/early loading group giving a failure rate of 6.3% for this group and 0% for two-stage implants. The failure rate was higher for flapless (7.9%) than for flap surgery (0%). The marginal bone loss was -2.4 mm (SD 1.5) for all implants, while 37.6% showed more than 3 mm of loss during the follow up. Bone loss increased with time of follow up. Implants subjected to immediate/early loading showed more bone loss than two-stage implants: -2.6 mm (SD 1.5) vs. -1.6 mm (SD 1.1). Moreover, 41.3% of immediately loaded and 22.7% of two-stage implants presented with more than 3 mm of bone loss. CONCLUSIONS: This short-term retrospective analysis showed a poor clinical outcome of Nobel Direct implants. Extensive marginal bone loss (>3 mm) was found around more than 1/3 of the implants evaluated. Less resorption and no failures were experienced when implants were allowed to heal from 6 weeks to 6 months before occlusal loading. Within the limitations of the present study design, data indicate that immediate loading, the use of this implant for multi-unit constructions and flapless surgery are risk factors for failure of Nobel Direct implants.