Dental implants in medically complex patients—a retrospective study

Clinical Oral Investigations - Dental implant insertion for oral rehabilitation is a worldwide procedure for healthy and medically compromised patients. The impact of systemic disease risks on the...     

Early implant failures in patients treated with Brånemark System titanium dental implants: a retrospective study

Implant failure has been associated with factors such as poor bone quality, insufficient bone volume, implant instability, unfavorable implant loading, and smoking habits. Infections and host responses may also be important factors in dental implant failure. The objectives of the present study were to identify various explanatory factors associated with titanium implant failure. Forty subjects with stage 1 non-osseointegrated titanium dental implants (NOTI) ad modum Br?nemark and 40 age- and gender-matched control subjects with successfully osseointegrated titanium implants (SOTI) were studied. Clinical data and gamma G immunoglobulin (IgG) antibody titers were studied. An independent t test revealed that significantly longer implants were placed in subjects with SOTI (P < .05). Statistically significant differences in bone shape and resorption (BSR) scores were found between SOTI and NOTI (P < .05). Logistic regression analysis identified 3 significant explanatory outcome variables: serum antibody avidity scores for Bacteroides forsythus (P < .0001), serum antibody titers to Staphylococcus aureus (P < .001), and the BSR scores (P < .05). Antibody avidity to B forsythus and antibody titer to S aureus were therefore the 2 most important factors associated with early implant failures and with a significant predictive ability. This indicates that immunologic factors are involved in osseointegration.     

Relation between insertion torque and bone–implant contact percentage: an artificial bone study

Objectives

The purpose of this study was to determine the correlation between the peak insertion torque value (ITV) of a dental implant and the bone–implant contact percentage (BIC%).

Material and methods

Dental implants were inserted into specimens comprising a 2-mm-thick artificial cortical shell representing cortical bone and artificial foam bone representing cancellous bone with four densities (groups 1 to 4—0.32, 0.20, 0.16, and 0.12?g/cm³). Each specimen with an inserted implant was subjected to micro-computed tomography (micro-CT) scanning, from which the 3D BIC% values were calculated. Pearson’s correlation coefficients (r) between the ITV and BIC% were calculated.

Results

The ITVs in groups 1 to 4 were 56.2?±?4.6 (mean±standard deviation), 45.6?±?0.9, 43.3?±?4.3, and 38.5?±?3.4?N?cm, respectively, and the corresponding BIC% values were 41.5?±?0.5%, 39.0?±?1.0%, 30.8?±?1.1%, and 26.2?±?1.6%. Pearson’s correlation coefficient between the ITV and BIC% was r?=?0.797 (P?<?0.0001).

Conclusion

The initial implant stability, quantified as the ITV, was strongly positively correlated with the 3D BIC% obtained from micro-CT images.

Clinical relevance

The ITV of a dental implant can be used to predict the initial BIC%; this information may provide the clinician with important information on the optimal loading time.     

Influence of crown–implant ratio on implant success rate of ultra-short dental implants: results of a 8- to 10-year retrospective study

Clinical Oral Investigations - The use of short implants has been suggested in recent years as an option for facilitating prosthetic restoration in resorbed jawbones. The aim of the present study...     

Marginal bone loss at implants: a retrospective, long-term follow-up of turned Brånemark System implants

Background: Lately, presence of progressive bone loss around oral implants has been discussed.
Purpose: The aim of this study was to report in a large patient group with different prosthetic restorations marginal bone level and its change as measured in radiographs obtained from prosthesis insertion up to a maximum 20 years in service. Further, it also aimed to study the impact of gender, age, jaw, prosthetic restoration, and calendar year of surgery.
Materials and Methods: Out of 1,716 patients recorded for clinical examination during 1999, 1,346 patients (78.4%) could be identified. A total of 640 patients (3,462 originally installed Brånemark System® implants, Nobel Biocare, Göteborg, Sweden) with a follow-up of ≥5 years were included in the study, while patients with continuous overdentures and augmentation procedures were not. Distance between the fixture/abutment junction (FAJ) and the marginal bone level was recorded.
Results: The number of implants with a mean bone level of ≥3 mm below FAJ increased from 2.8% at prosthesis insertion to 5.6% at year 1, and 10.8% after 5 years. Corresponding values after 10, 15, and 20 years were 15.2, 17.2, and 23.5%, respectively. Implant-based bone loss was as a mean 0.8 mm (SD 0.8) after 5 years, followed by only minor average changes. Mean bone loss on patient level followed a similar pattern. Disregarding follow-up time, altogether 183 implants (107 patients) showed a bone loss ≥3 mm from prosthesis insertion to last examination. Significantly larger bone loss was found the older the patient was at surgery and for lower jaw implants.
Conclusions: Marginal bone support at Brånemark implants was with few exceptions stable over years.     

Influence of bicortical or monocortical anchorage on maxillary implant stability: a 15-year retrospective study of Brånemark System implants

The present study evaluated implant survival and marginal bone loss in maxillae over a 15-year follow-up period as a function of either monocortical or bicortical implant anchorage. Of 207 standard Br?nemark implants (10 mm in length) followed, 110 implants were judged to be monocortically anchored and 97 as bicortically anchored. The bicortically anchored implants failed nearly 4 times more often than the monocortical ones. Implant fractures accounted for over 80% of the observed failures and were found to affect the bicortical group almost 3 times more often. As tentative explanations, induction of increased stress and bending forces resulting from possible prosthetic misfit, presence of unfavorable arch relationships, or high occlusal tables in combination with bicortically anchored implants have been suggested, all indicating an overambitious fixation of the bicortical anchorage. Total marginal bone loss was low over the 15-year period and close to identical for the 2 groups, suggesting that the mode of cortical anchorage did not have any clinically significant influence on marginal bone remodeling.     

Radiologic bone loss in patients with bisphosphonate-associated osteonecrosis of the jaws: a case–control study

Objectives

Most patients with bisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) report a previous tooth extraction at the necrosis site before the diagnosis was made. At older ages, most teeth are extracted due to periodontal disease, which is per se another BP-ONJ trigger factor. The aim of this study was to evaluate the periodontal status of BP-ONJ patients using panoramic radiographs compared to a control.

Materials and methods

All patients treated for BP-ONJ up to January 1, 2010 comprised the study. The very first panoramic radiograph was analyzed. The number of remaining teeth and the radiographic bone loss from the cemento-enamel junction to the crestal bone were measured. For each patient, one control was analyzed (matching for gender and age).

Results

One hundred twenty-nine BP-ONJ panoramic radiographs and 129 controls were analyzed (68 women, 61 men; 67.3?±?9.7 years; osteoporosis [n?=?11], breast cancer [n?=?33], multiple myeloma [n?=?61], prostate cancer [n?=?24]). The average number of remaining teeth was 12.9?±?8.4 for BP-ONJ and 16.4?±?9.4 for the control (p?=?0.02). The average radiographic bone loss was 5.5?±?2.3 mm for BP-ONJ and 3.1?±?1.1 mm for the control (p?<?0.001); 96.6 % of BP-ONJ and 77.5 % had radiographic bone loss of more than 5 mm. Radiographic bone loss in the molar region was the highest for both groups (BP-ONJ 6.0?±?2.3 mm; control 3.6?±?1.4 mm).

Conclusion

Prevalence and severity of periodontal disease in patients with BP-ONJ is higher compared to healthy controls.

Clinical relevance

Patients with periodontal disease might be at a higher risk of developing BP-ONJ; therefore, periodontal disease therapy in patients who are about to receive bisphosphonates should be undertaken.     

Clinical outcome of Brånemark System implants of various diameters: a retrospective study

PURPOSE: The purpose of this study was to evaluate the outcome of the 3 different diameters of Br?nemark System implants, with special focus on the 5.0-mm-diameter implant. MATERIALS AND METHODS: Ninety-eight patients (99 jaws) with a mean age of 62 years were included in this retrospective report. The mean follow-up period was 2 years and 8 months. A total of 379 Br?nemark System implants (3.75 mm diameter, n = 146; 4.0 mm diameter, n = 76; 5.0 mm diameter, n = 157) were placed in 29 edentulous and 70 partially edentulous jaws. RESULTS: Eight of the 146 implants in the 3.75-mm-diameter group failed (5.5%). The corresponding figures for the 4.0- and 5.0-mm-diameter implants were 3 of 76 (3.9%) and 7 of 157 (4.5%), respectively. DISCUSSION: All failures were recorded in maxillae, ie, 18 of the 298 placed, and the majority of these were found in bone quantity group B and quality group 2. Only 3 implants of 131 failed in bone judged as quality 4. The marginal bone loss was low for the 3 implant diameter groups. CONCLUSION: The favorable outcome in bone of poor quality is ascribed partly to the use of an adapted preparation technique and extended healing periods for achievement of the best primary and secondary implant stability possible.     

Oral implants in combination with bone grafts. A 3-year retrospective multicenter study using the Br?nemark implant system.

A retrospective, multicenter, Scandinavian study of bone grafting of alveolar processes of severely atrophic jaws in combination with implant insertion was conducted with 150 patients. Five different grafting techniques were assessed: local or full onlay; inlay; combination of onlay/inlay grafts; and LeFort I osteotomies. The majority of the patients were treated using a one-stage approach (n = 125) and all had autogenous bone grafts. A total of 781 Br?nemark implants were inserted, of which 624 were placed in bone grafts and alveolar bone. Twenty-five patients (17%) dropped out during the follow-up period of three years. Within the remaining patients, 77% of the inserted implants (n = 516) were still in function at the end of the follow-up period. A further ten implants were kept mucosa-covered, resulting in an overall implant survival rate of around 80%. Onlays, inlays and LeFort I osteotomies showed almost the same success rates (76-84%), whereas the onlay/inlay technique gave rise to less favourable results (60%). Most of the observed losses (n = 131) took place during healing and the first year of loading. More implants were lost when they were inserted simultaneously with the grafting (23%) than when they were placed in a second stage (10%). The latter technique was used mainly in combination with local onlay grafting (16/25). The failure percentage for implants inserted in non-grafted bone (11%) was lower than for those inserted in bone grafts and alveolar bone (25%). The surviving implants of treated and followed patients served, in 88% of the cases (n = 110), to support fixed bridges or overdentures, albeit, in some instances (n = 23), after additional implant placement. In only 15 patients was it necessary to fall back on conventional removable prostheses or fixed partial bridges.     

Tapered implants in jaws with soft bone quality: a clinical and radiographic 1-year study of the Brånemark System Mark IV fixture

Background: The survival rate of oral implants in soft‐quality bone has been demonstrated to be inferior to that of implants inserted in good‐quality bone. A possible way to increase the survival rate in soft‐quality bone may be to use a tapered implant. Such an implant has been developed and manufactured by Nobel Biocare AB, Gothenburg, Sweden. So far, there have been only a few publications regarding this implant. Purpose: The aim of the study was to compare the outcome of using the tapered Branemark System Mark IV fixture with the outcome of using earlier Brånemark fixtures in a controlled prospective study. Materials and Methods: The study was performed as a multicenter study including seven specialist centers. The material consisted of 40 patients in need of implant‐supported bridges in the maxilla. Twenty‐five patients belonged to the test group, in which the tapered Mark IV implants were inserted, and 15 patients belonged to the control group, in which Branemark Standard or Mark II implants were used. The patients were allocated to the test group or the control group according to randomization schedules. The implants were inserted according to the guidelines for Branemark implants. A two‐stage surgical protocol was used, and abutment connection was made 6 months after fixture insertion. The test group comprised 97 Mark IV implants, and the control group made up 92 implants. The prosthetic procedure followed the guidelines for Brånemark implants, and all patients were provided with full fixed maxillary bridges. The patients were followed up with clinical and radiographie records for 1 year after loading. Results: The survival rate was 96.9% for the Mark IV implants and 98.9% for the control implants. There was no significant difference between the two groups. There was a mean marginal bone loss of 0.2 mm during the observation period, and there was no difference between test implants and control implants. Conclusions: With regard to survival rate and marginal bone level changes, no differences could be demonstrated between the Mark IV tapered implant and the Brånemark implants used earlier. However, compared with earlier results of Brånemark implants in soft‐quality bone, the Mark IV implant demonstrated an improved survival rate.     

Primary reconstruction of combined orbital and zygomatic complex fractures with patient-specific milled titanium implants – A retrospective study

The aim of this retrospective study was to compare mid-facial symmetry and clinical outcomes between patients treated with patient-specific and standard implants in primary fracture reconstructions of combined orbital and zygomaticomaxillary complex fractures.Patients who underwent primary reconstruction of orbital and zygomaticomaxillary complex fractures during the study period were identified and background and clinical variables and computed tomography images were collected from patient records. Zygomaticomaxillary complex dislocation and orbital volume were measured from pre- and postoperative images and compared between groups.Out of 165 primary orbital reconstructions, eight patients treated with patient-specific and 12 patients treated with standard implants were identified with mean follow-up time of was 110 days and 121 days, respectively. Postoperative orbital volume difference was similar between groups (0.2 ml for patient-specific vs 0.3 ml for standard implants, p = 0.942) despite larger preoperative difference in patient-specific implant group (2.1 ml vs 1,5 ml, p = 0.428), although no statistical differences were obtained in symmetricity or accuracy between the reconstruction groups.Within the limitations of the study it seems that patient-specific implants are a viable option for primary reconstructions of combined zygomaticomaxillary complex and orbital fractures, because with patient-specific implants at least as symmetrical results as with standard implants can be obtained in a single surgery.     

Accuracy of laser-melted patient-specific implants in genioplasty — A three-dimensional retrospective study

PurposeTo assess the accuracy of laser-melted patient-specific implants (PSI) with regard to a preoperative virtual treatment plan for genioplasty based on a new analysis method without the use of landmarks.Materials and methodsA retrospective evaluation of a cohort of Class II and Class III patients who had undergone virtually planned orthognathic surgery (including genioplasty) was carried out. The preoperative virtual treatment plan and the postoperative outcome were fused to calculate the translational and rotational discrepancies between the 3D planning and the actual surgical outcome.ResultsThe accuracy of left/right positioning was 0.25 ± 0.28 mm (p < 0.001), that of anterior/posterior positioning was 0.70 ± 0.64 mm (p < 0.001), and that of up/down-positioning was 0.45 ± 0.38 mm (p < 0.001). The rotational discrepancies were less than 2 deg. The virtually planned and postoperative positions of the chin differed significantly from each other (p < 0.001 for all rotational and translational discrepanices).ConclusionThe findings demonstrate that PSIs can transfer the planned virtual genioplasty into the operation theatre with small but significant deviations. However, since no conclusions can be drawn from the results regarding surgical success in terms of shaping the soft tissue profile as well as the esthetic result, no superiority of PSI over traditional plate osteosynthesis can be demonstrated.     

Outcome of Brånemark Novum implant treatment in edentulous mandibles: a retrospective 5-year follow-up study

Background: A gradual progression from a two‐stage surgical technique to a one‐stage and even immediate surgical protocol has occurred during the last decade with most oral implant systems. However, every new approach must obviously be reported individually, with long‐term results, in order to assess whether the changes have any real patient value. Purpose: The aim of the present report was to retrospectively review the 5‐year outcome of patients treated with the Brånemark Novum® (Nobel Biocare AB, Göteborg, Sweden) protocol. Methods: The first 15 patients treated according to the Novum procedure in a private specialist clinic in Lovere, Italy, were followed‐up with clinical, radiographic, and resonance frequency analyses. All the patients’ fixed constructions had been in function for an average of 5 years. Parameters recorded were implant survival, prosthesis success, oral hygiene and mucosal health, marginal bone remodeling, type and frequency of complications, and patient's opinion of the treatment outcome. Results: After 5 years, the cumulative survival rate for implants was 91%, and for inserted bridge constructions it was 87%. Very small changes in implant stability occurred during implant loading from 1 to 5 years. Oral health conditions were good; 87% of mucosal quadrants around the implants were free from signs of inflammation. Very small marginal bone height changes were observed at the implants during the examination period, and except for four implant losses reported, severe complications were few. All patients were satisfied with the functional outcome of their constructions, but two patients were not completely happy with the aesthetics of their bridgework as supplied. Conclusion: This report shows 5‐year evidence of acceptably good results with the Brånemark Novum implant technique in edentulous mandibles, when using only three implants to support the fixed bridge construction, and as long as inserted implants become and remain osseointegrated.     

Biomechanical effects of the implant material and implant–abutment interface in immediately loaded small-diameter implants

Objective

Small-diameter implants have been available since the 1990s, but few studies have analyzed their mechanical properties. This study evaluated the effects of the implant material and the implant–abutment connection designs on the primary stability and the marginal bone strain of small-diameter implant subject to immediate loading.

Materials and methods

Insertion torque value (ITV), implant stability quotient (ISQ), and Periotest value (PTV) of three implant systems with four parameters (titanium, titanium alloy, internal and external hexagon connections) were measured after placing implants into artificial type 2 jaw-bone models. Specimens were tested under both vertical and oblique static loads at 190 N. Peak values of the principal bone strain were recorded and analyzed statistically by the Kruskal–Wallis test and multiple-comparisons Bonferroni test.

Results

PTV and ISQ were higher for the NIOSM311 (internal-hex and Ti alloy) and FOSM311 (external-hex and pure Ti) implants, respectively, than for the NOSM311 (external-hex and Ti alloy) implant. Under vertical loading the peak value of peri-implant bone strains did not differ significantly among these three implant systems. However, the peak bone strains were at least 32 % lower for the NIOSM311 and FOSM311 implants than for the NOSM311 implant under lateral loading.

Conclusions

The implant material and the implant–abutment connection design significantly influence the peri-implant bone strain of immediately loaded small-diameter implants, but barely affect their primary stability.

Clinical Relevance

A commercially pure titanium implant with an internal connection has the potential to reduce the risk of implant failure of small-diameter implant related to biomechanical complications.     

Marginal bone reaction to oral implants: a prospective comparative study of Astra Tech and Brånemark System implants

Abstract: In earlier studies of Astra Tech and Brånemark System implants, high survival rates and small marginal bone changes have been demonstrated. The aim of this study was to compare the two systems, primarily with regard to marginal bone changes, but also with regard to other clinical variables of interest. The present paper describes the results after three years. Sixty‐six patients were included in the study and randomly assigned to treatment with Astra Tech implants (n=184) or Brånemark System implants (n=187). The marginal bone level was radiographically examined at fixture insertion, at abutment connection, at baseline (delivery of the prosthetic construction) and at 1‐ and 3‐year follow‐up examinations. Between fixture insertion and the baseline examination, the pattern of marginal bone resorption differed between the two systems. However, there was no significant marginal bone change between baseline and the 1‐year examination or between the 1‐ and 3‐year examinations. Nor were there any differences between the systems. The mean bone loss in the upper jaw between BL (baseline) and 3 years was 0.2±0.3 mm for Astra Tech implants and 0.2±0.1 mm for Brånemark System implants. The corresponding figures for the lower jaw were 0.3±0.2 mm and 0.2±0.1 mm. The survival rate of Astra Tech implants was significantly higher (98.9%) than for Brånemark System implants (95.2%). However, five of the nine implant losses in the Brånemark group occurred in one patient. For that reason, this result must be interpreted with caution. The number of patients with implant losses did not differ significantly between the systems. Few complications were recorded up to 3 years.