First Year Of Loading Research Articles

Evaluation of the Success Criteria for Zirconia Dental Implants: A Four-Year Clinical and Radiological Study

Objectives. The aim was to evaluate survival and success rates, soft tissue health, and radiographic marginal bone loss (MBL) of zirconia implants placed in the esthetic and posterior areas of the jaws and in association with multiple or single implant restorations after at least 6 months of definitive restoration. Material and Methods. 35 one-piece zirconium implants were utilized for single or partially edentulous ridges rehabilitation. All implants received immediate temporary restorations and six months after surgery were definitively restored. Every 6 months after implant placement, a clinical-radiographic evaluation was performed. For each radiograph, the measurements of MBL were calculated. Results. The results showed that the mean MBL at 48-month followup was 1.631 mm. The mean MBL during the first year of loading was not more significant for implants placed in the first molar regions than for those positioned in other areas. Moreover, no differences in marginal bone level changes were revealed for multiple and single implants, whereas MBL in the first year was observed to be slightly greater for implants placed in the maxilla than for those placed in the mandible. Conclusion. Zirconia showed a good marginal bone preservation that could be correlated with one-piece morphology and characteristics of zirconia implants.

Piezoelectric Alveolar Ridge-Splitting Technique with Simultaneous Implant Placement: A Cohort Study with 2-Year Radiographic Results

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

Multiple teeth replacement with endosseous one-piece yttrium-stabilized zirconia dental implants

Objectives: The purpose of this study is to clinically and radiographically evaluate survival and success rate of multiple zirconia dental implants positioned in each patient during a follow-up period of at least 12 months up to 48 months. Study Design: Eight patients were treated for multiple edentulism with 29 zirconia dental implants. All implants received immediate temporary restorations and 6 months after surgery were definitively restored. 6 months to 4 years after implant insertion, a clinical-radiographic evaluation was performed in order to estimate peri-implant tissues health and peri-implant marginal bone loss. Results: Survival rate within follow-up period was therefore 100%. The average marginal bone loss (MBL) from baseline to 6 months was +1.375±0.388 mm; from 6 months to 1 year was +0.22±0.598 mm; from 1 year to 2 years was -0.368±0.387 mm; from 2 years to 3 years was -0.0669±0.425 mm; from 3 years to 4 years +0.048±0.262 mm. The mean marginal bone loss at 4 years from the implants insertion was +1.208 mm. Conclusions: According to several studies, when using a radiographic criterion for implant success, marginal bone loss below 0.9-1.6 mm during the first year in function can be considered acceptable. In our work, radiographic measurements of MBL showed values not exceeding 1.6 mm during the first year of loading and also 1 year up to 4 years after surgery further marginal bone loss was minimal and not significant. This peri-implant bone preservation may be associated to the absence of micro-gap between fixture and abutment since zirconia dental implants are one-piece implant. Moreover, zirconia is characterized by high biocompatibility and it accumulates significantly fewer bacteria than titanium. Key words:Zirconia dental implants, multiple implants, radiographic evaluation, marginal bone loss (MBL).

Sleeping vs. loaded implants, long‐term observations via a retrospective analysis

Several theories have been presented to explain initial and secondary marginal bone loss around dental implants (e.g. microbial load, adverse loading, microbial leakage, compromised healing/adaptation of host-implant interface). This study compared the long-term outcome (up to 12 years) of sleeping with loaded implants in the mandible via a split-mouth concept. Fourteen patients with overdentures were enrolled (10 women, mean age at implant insertion: 56 years [range: 33-71]). They presented with 28 loaded (position 33/43) and 14 sleeping implants (mostly position 31/41). At several follow-up visits, intra-oral radiographs (long-cone principle) were taken to observe marginal bone level changes. At each observation, compared with abutment connection, the submerged non-loaded implants showed less bone loss (P-values: 1st year 0.007, 3 years 0.000, 5 years 0.002, 8 years 0.007, 12 years 0.000) than their neighbouring functional implants. This difference was primarily due to a more significant bone loss during the first year of loading (0.8 vs. 0.1 mm respectively), since afterwards, the bone level changes remained quite similar for both implant types. Our data suggest that the first months of loading have a significant impact on the bone level (initial difference sleeping vs. loaded implants), followed by a more physiological bone level change afterwards. This initial difference might be explained by the adaptation of the surrounding bone to the loaded implant.

Marginal Bone‐Level Alterations at Implants Installed in Block versus Particulate Onlay Bone Grafts Mixed with Platelet‐Rich Plasma in Atrophic Maxilla. A Prospective 5‐Year Follow‐Up Study of 15 Patients

Extensive atrophy of the alveolar process may require a bone-grafting procedure prior to implant treatment. Autogenous bone grafts from the iliac crest, used as onlay block and particulate bone, have been used together with sinus-lift procedure in order to rehabilitate patients with extremely resorbed maxillae. However, there are to our knowledge no 5-year follow-up studies evaluating the extent of bone-level change in patients treated with respectively block and particulate autogenous bone grafts. The purpose of this prospective clinical study was to conduct a 5-year follow-up analysis with focus on bone-level alteration in block versus particulate onlay bone grafts. Fifteen out of originally 19 patients who were treated with iliac bone grafts and oral implants in the maxilla have been followed through the first 5 postoperative years. In a first study conducted on 19 patients, the role of platelet-rich plasma in conjunction with autogenous bone was evaluated. In this 5-year follow-up study, the marginal bone alterations have been documented at base line, 1 year and 5 years of loading to the nearest 0,1 mm at mesial and distal surfaces of the implants. Two implants were installed on each side of the midline in either block or particulate bone grafts giving test and control sides in each patient. Additionally, two implants on each side were installed in residual bone/grafted sinus floor. Marginal bone alteration in the anterior maxilla appeared larger at the side augmented by block bone at baseline, and after 1 and 5 years of loading, but the change was not statistically significant. Moreover, there was a significantly higher degree of marginal alteration during the first year of loading, compared with the examinations after 5 years. The present follow-up study showed that there is no significant difference in the extension of resorption between block- and particulate autogenous bone grafts over a 5-year period. Most of the resorption occurred during the first year in function.

Implant Placement in Combination with Sinus Membrane Elevation without Biomaterials: A 1‐Year Study on 15 Patients

Membrane elevation in combination with implant placement without biomaterials is a rather new technique proposed for sinus lifting. This study assessed the clinical outcome of such technique during the first year of loading. Fifteen patients with a mean residual bone height of 6.2 mm were consecutively recruited for sinus lifting. After opening a replaceable bone window, the membrane was dissected from the sinus walls. A total of 28 implants were placed in the residual crest and they kept the membrane lifted upwards. After window repositioning, the flap was sutured. A 6-month healing period was allowed. Patients were re-examined after 12 months of loading. All the implants survived at the end of the follow-up. The 5.5 mm mean bone reformation was significantly lower than the 8.2 mm mean membrane lift achieved after implant placement. Regeneration at the distal surface of the most posterior implants was significantly less than at other aspects. The height of membrane lift was not correlated with the amount of regenerated bone. All of the 28 implants placed in combination with sinus membrane elevation were stable during the first year of loading. No extra costs for biomaterial or morbidity for bone harvesting were necessary.

Long‐term, retrospective evaluation (implant and patient‐centred outcome) of the two‐implant‐supported overdenture in the mandible. Part 2: marginal bone loss

In part 2 of this long-term, retrospective study on the two-implant-supported overdenture in the mandible, the annual marginal bone loss was evaluated in detail and parameters, with a significant effect on the annual bone loss, were verified. For all 495 patients with an overdenture in the mandible at least 5 years in function, data up to their last follow-up visit had been collected, including long-cone radiographs (taken at the abutment connection and after years 1, 3, 5, 8, 12 and 16 of loading) and probing data at their last evaluation. General information (medical history, implant data, report on surgery) was retrieved from the patient's file. Two hundred and forty-eight patients had been clinically examined recently. For the others, information on bone level and probing depths were retrieved from the patient's files, as all patients had been enrolled in our annual follow-up schedule. The mean annual bone loss on a site level (without considering the first year of bone remodelling) after 3 years of loading was 0.08 mm/year (SD=0.22, n=1105), after 5 years of loading 0.07 mm/year (SD=0.14, n=892), after 8 years of loading 0.06 mm/year (SD=0.12, n=598), after 12 years 0.04 mm/year (SD=0.07, n=370) and 0.05 mm/year (SD=0.05, n=154) after 16 years of loading. Ongoing bone loss was seen in a number of implants (n=26) with the annual bone loss exceeding 0.2 mm. Some factors clearly showed a significant impact on bone loss: smoking (> or =10 cigarettes/day), GBR, the presence of dehiscence and bone quantity(the latter only during the first year). The probing data showed a favourable condition, with <1.2% of the approximal pockets being > or =6 mm, and 4.1%=5 mm. The mean annual bone loss over the study period was <0.1 mm/year after the first year of loading. However, a small number (2.5%) of the implants showed continuing bone loss.

Stability values of titanium dioxide‐blasted dental implants in edentulous maxillas: a 3‐year pilot study

The purpose of this follow-up study was to measure the resonance frequency of Astra Tech TiO(2) blasted implants at second surgery, at one and 3 years of loading. Secondly, it was investigated whether resonance frequency at second surgery could discriminate between successful implants and those that will fail over a 3-year period. Fifty titanium dioxide-blasted implants in eight consecutive patients with edentulous maxillas seeking fixed rehabilitations, were included in the study at abutment connection after 6 months of healing. Resonance frequency, clinical and radiographic records were obtained at abutment connection and after one and 3 years of loading. The cumulative survival rate after 3 years was 100%. The mean resonance frequencies were 65 +/- 4.8 implant stability quotient (ISQ) at second surgery (range 50-78 ISQ), 66 +/- 3.4 ISQ after 1 year of loading (range 53-76 ISQ) and 64 +/- 3.8 ISQ after 3 years of loading (range 53-77 ISQ). No significant differences resulted between these three time points. The marginal bone level decrease of 0.6 mm between the second surgery and the 3-year follow-up was observed. One limitation of the study is that no late failures were encountered in this relatively small sample. Consequently, it was not possible to establish a cut-off ISQ for implants that, after abutment connection, would maintain their stability over a 3-year period. Nevertheless, it might be concluded that following the first year of loading the range of 53-76 ISQ describes the stability of osseointegrated Astra Tech TiO(2) blasted implants.

One‐year outcome of narrow diameter blasted implants for rehabilitation of maxillas with knife‐edge resorption

This study aimed at assessing the clinical outcome of narrow diameter implants in the treatment of knife-edge edentulous maxillas of adequate bone height but inadequate width (class IV of Cawood and Howell). Twelve consecutive patients (eight women and four men, mean age 58 years) with class IV atrophic edentulous maxillas were included in the study. Seventy-three microthreaded TiO(2)-blasted implants were placed and the resonance frequency measured. All the implants had a diameter of 3.5 mm. After 6 months of submerged healing, fixed implant-supported prostheses were delivered to the patients and resonance frequency and radiographic examinations performed. After the first year of loading, the implant outcome was again evaluated clinically, radiographically and with resonance frequency analysis. All the implants were followed up to 1 year of loading and their survival rate was 100%. Bone loss after 1 year of loading was (mean+/-SD) 0.30+/-0.13 mm. Stability values were (mean+/-SD) 63+/-5.8 ISQ at placement, 60+/-4.7 ISQ at the abutment connection and 61+/-5 ISQ after 1 year of loading. A significant difference resulted between placement and abutment connection values (P=0.03). According to the present study, narrow implants may be used to restore edentulous maxillas with atrophies of class IV of Cawood and Howell. When planning the treatment of edentulous maxillas with such a resorption pattern, this possibility has to be considered as an alternative to more demanding grafting techniques.

Five-year Outcome of 111 Immediate Nonfunctional Single Restorations

Immediate loading is a surgical-prosthetic procedure extensively used in implant dentistry. Despite its frequent use, minimal data are available on the long-term clinical success rate of immediate functional loading (IFL) and immediate nonfunctional loading (INFL) of implants. The aim of this study was to evaluate the long-term survival and bone loss of immediate nonfunctional single implant restorations in a group of patients that were monitored for 5 years. One hundred and eleven patients (41.4% men) with a median age of 40 years were included in this study. A total of 111 implants were placed. All implants were placed with a minimum insertion torque of 25 Ncm. A temporary restoration was relined with acrylic resin, trimmed, polished, and cemented or screw-retained 1 to 2 hours later. Occlusal contact was avoided in centric and lateral excursions. After provisional crown delivery, a periapical radiograph was performed by means of a customized Rinn holder device. Data were analyzed by means of Kaplan-Meier and life-table algorithms. Stratification of implant survival was performed for the available variables of interest, and comparisons were analyzed using a log-rank test. Investigated parameters were time of implant placement, bone quality, implant site, implant diameter and length, and type of implant surface enhancement. The parameters for overall success rate were defined by bone resorption <1.5 mm after the first year of loading and <0.2 mm thereafter. During the 5-year follow-up period, a survival rate of 95.5% was observed. All failures occurred within 4 months of implant loading. There were statistically significant differences regarding healed vs post-extraction implant sites (100% and 92.5%, respectively, P = .05) and type of bone (D1 vs D4 yielded 100% and 95.5%, respectively, P <.05). No differences were detected for: (1) site (100% for mandible and 94.63% for maxilla, P =-.319); (2) implant diameter (survival rates of 97.26% for <4.5-mm diameter and 92.11% for >4.5mm diameter, P = .206); (3) implant lengths (survival rates of 96.97% for implants >13 mm and 94.87% for implants <13 mm, P =.624); and (4) type of implant surface enhancement (survival rates of 94.03% for 67 cases of grit-blasted and acid-etched surfaces and a failure rate of 4 out of 5, and 94.12% for 17 cases of hydroxyapatite (HA)-coated surfaces with only 1 failure). The success rate (defined as bone resorption >1.5 mm after the first year of loading and >0.2 mm thereafter) was 97.2%. Immediate nonocclusal loading of single implants is a reliable surgical-prosthetic procedure with a low rate of implant loss and a low quantity of peri-implant bone loss over time.

Long-term treatment outcomes in edentulous patients with implant overdentures: The Toronto Study

Few long-term studies on overdentures report both implant and prosthodontic outcomes. The aim of this prospective study was to report long-term prosthodontic- and implant-related treatment outcomes of patients treated with design-specific implant-supported overdentures. Between 1982 and 1992, 45 consecutively treated patients received a total of 47 overdentures (42 mandibular and 5 maxillary) supported by Brånemark implants. Prospective clinical and radiographic data were collected over the observation period; this study presents the most recent treatment outcomes. Thirty patients (mean age 70 years) with 32 prostheses attended the final recall visit, with 67% of patients followed for 15.53 years (range 10 to 19 years). Six implants failed, and the prosthetic plan and implant cumulative survival rates were both in excess of 90%. Mean marginal bone loss around implants after the first year of loading was small (0.05 mm/year), although the individual variation was high. Linear regression analysis of bone loss indicated that gender, bicortical stabilization, bone quality, and healing time were predictors of bone loss for the first year of loading but not for the ensuing years. Prosthetic maintenance included fractured components, denture relining, and replacement of prostheses. On average, the longevity of overdenture prostheses was 12 years, and laboratory relining was necessary every 4 years. This study confirmed the long-term outcome success of patients treated with design-specific overdenture prostheses supported by Brånemark implants. However, prosthetic maintenance was required, a fact that should be discussed with patients prior to treatment.

Long-term treatment outcomes in edentulous patients with implant-fixed prostheses: The Toronto Study

The aim of this prospective study was to report long-term treatment outcomes (prosthetic and implant related) of edentulous patients treated with implant-supported fixed prostheses who participated in the first clinical implant study in North America. Forty-five patients were treated with Brånemark implants supporting a total of 47 fixed prostheses (42 mandibular and 5 maxillary) between 1979 and 1984. All patients were recalled regularly for comprehensive prospective clinical and radiographic assessments. Thirty-one patients (33 prostheses) attended a final recall visit in 2002; 71% of patients had been followed for 20 years (range 18 to 23 years), with overall prosthetic plan and implant outcome success rates of 84% and 87%, respectively. Mean marginal bone loss around the implants after the first year of loading was small (0.05 mm/year), with high individual variations. Poor oral hygiene, smoking history, and implant position appeared to be predictors of marginal bone loss. Prosthetic maintenance was ongoing and included fractured components and replacement of prostheses; the longevity of a fixed prosthesis for this group of patients was 8.39+/-5.30 years. This study confirmed the overall long-term treatment outcome success of patients treated with fixed prostheses supported by Brånemark implants. Successful osseointegration with a small mean bone loss was maintained as study patients aged, although prosthetic maintenance was required. The latter consideration should be discussed with all patients seeking such treatment.

Crestal bone loss proximal to oral implants in older and younger adults

Statement of problem Older adults often have bone loss and may be at risk of bone resorption around oral implants. Purpose This study tested the hypothesis that there is no difference in crestal bone loss proximal to oral implants in the complete implant prosthesis sites of older and younger adults. Material and methods Two groups of 35 complete dental implant prosthesis sites (23 screw-retained fixed prostheses and 12 bar-retained overdentures) were selected by matching sites in 32 older adults (60 to 74 years old with 166 Bränemark implants) to sites in 34 younger adults (29 to 49 years old with 162 Bränemark implants) on the basis of possible confounding factors including gender, prosthetic design, implant number, arch, year of surgery, and opposing dentition. Statistical comparisons (Mann-Whitney test at P<.05) were made of mean crestal bone level at loading and mean annual crestal bone loss during the first year, first to fourth year, after first year, and after fourth year of loading with periapical radiographic measurements of the vertical distance in millimeters from the apical edge of the implant collar to the most apical initial point of contact between the implant and bone. Results No significant differences were found between the groups. Mean bone levels at loading were 1.4 mm below the collar in both groups and mean annual crestal bone loss after the first year of loading was 0.04 mm/y in both groups. However, significant differences were found between some old and young subgroups stratified by arch and prosthetic design. Conclusion Within the limitations of this study, elders should expect no more rapid bone resorption around oral implants in edentulous jaws than that seen in young adults.

Implant-retained mandibular overdentures with immediate loading: a 3- to 8-year prospective study on 328 implants.

The purpose of this study is to evaluate prospectively survival and success rates of implants placed in the interforaminal area of edentulous mandibles and immediately loaded with an implant-supported overdenture. Eighty-two patients, 33 males and 49 females, aged between 42 and 87 years (mean age 58.6 yr), presenting edentulous mandibles were rehabilitated with an implant-supported overdenture in the mandible. Three hundred twenty-eight screw-type osseointegrated implants (164 Ha-Ti, Mathys Dental, Bettlach, Switzerland; 84 ITI Dental Implant System, Straumann Institute, Waldenburg, Switzerland; 40 Brånemark Conical, Nobel Biocare AB, Gothenburg, Sweden; 40 Frialoc, Friatec, AG Mannheiti, Germany), were placed in the intraforaminal area of the mental symphysis (4 implants per patient). Immediately after implant placement, a U-shaped gold or titanium bar was fabricated and implants were rigidly connected with the bar and immediately loaded with an implant-retained overdenture. Success rate of implants was evaluated clinically and radiographically every year after the loading of the prostheses according to the following parameters: (1) absence of clinical mobility of implants tested individually after bar removal, (2) absence of periimplant radiolucency evaluated on panoramic radiographs, (3) absence of pain and radiologic or clinical signs of neural lesion, and (4) periimplant bone resorption mesial and distal to each implant less than 0.2 mm after the first year of prosthetic load. Of 328 implants placed, 296 were followed up from a minimum of 36 months to a maximum of 96 months, with a mean follow-up of 62 months. Seven implants in 6 different patients were removed owing to loss of osseointegration, whereas 18 implants, although still osseointegrated, did not fulfill success criteria due to bone resorption > 0.2 mm/year after the first year of loading. Despite implant losses, all patients maintained their bars supporting overdentures, although in 6 patients they were supported by 3 instead of 4 implants. The only patient who lost 2 implants received 2 new implants, which survived normally. Therefore, the absolute success and survival rates were 91.6% and 97.6%, respectively, whereas the cumulative survival and success rates of implants obtained with a life table analysis were 96.1% and 88.2%, respectively. Results of this study seem to demonstrate that survival and success rates of immediately loaded implants placed in the intraforaminal area of the mandible and rigidly connected with a bar through an implant-supported overdenture are consistent with those reported in the international literature as far as delayed loading is concerned after 3 years of loading. After longer observation times, this study demonstrated that, while survival rates of implants and bar-supported overdentures are still consistent with results published in the international literature pertaining to delayed loading, a moderate decrease in success rates of implants was found. Nevertheless, it must be stressed that this decrease (88.8 and 90.4% after a 7- to 8-year observation period for Ha-Ti and ITI implants) is related only to two implant systems; no data are available for the other two implant systems because of the shorter follow-up period.

Microbiological findings and host response in patients with peri-implantitis.

The aim of the present study was to characterise microbiota and inflammatory host response around implants and teeth in patients with peri-implantitis. We included 17 partly edentulous patients with a total of 98 implants, of which 45 showed marginal bone loss of more than three fixture threads after the first year of loading. Nineteen subjects with stable marginal tissue conditions served as controls. Oral hygiene, gingival inflammation, and probing pocket depth were evaluated clinically at teeth and implants. Microbiological and crevicular fluid samples were collected from five categories of sites: 1) implants with peri-implantitis (PI), 2) stable implants (SI) in patients with both stable and peri-implantitis implants, 3) control implants (CI) in patients with stable implants alone, 4) teeth in patients (TP) and 5) controls (TC). Crevicular fluid from teeth and implants was analysed for elastase activity, lactoferrin and IL-1 beta concentrations. Elastase activity was higher at PI than at CI in controls. Lactoferrin concentration was higher at PI than at SI in patients with peri-implantitis. Higher levels of both lactoferrin and elastase activity were found at PI than at teeth in patients. The concentrations of IL-1 beta were about the same in the various sites. Microbiological DNA-probe analysis revealed a putative periodontal microflora at teeth and implants in patients and controls. Patients with peri-implantitis harboured high levels of periodontal pathogens, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Prevotella intermedia, Bacteroides forsythus and Treponema denticola. These findings indicate a site-specific inflammation rather than a patient-associated specific host response.

A prospective 1-year clinical and radiographic study of implants placed after maxillary sinus floor augmentation with bovine hydroxyapatite and autogenous bone

Purpose: The purposes of this study were 1) to evaluate the survival rate of implants placed in maxillary sinuses augmented with bovine hydroxyapatite and autogenous bone 6 months before implant surgery and 2) to estimate dimensional changes of the bone graft with time using a new radiographic method. Patients and Methods: Thirty maxillary sinuses in 20 consecutive patients with severe resorption (mean, 3.8 mm of remaining alveolar bone) were augmented with a mixture of 80% bovine hydroxyapatite and 20% autogenous bone mixed with fibrin glue to enable the placement of screw-shaped dental implants. After 6 months of primary healing, 108 implants were placed and followed with clinical and radiographic examinations during the first year of loading. Measurements of changes in height, width, and length of the grafted material were made on tomographic Scanora (Soredex Orion Corporation Ltd, Helsinki, Finland) and panoramic radiographs taken 3 and 12 months after grafting and after 1 year of bridge loading. Results: Ten implants in 6 patients were lost during the study (9 before loading and 1 after 1 year of functional loading), for a survival rate of 90.7%. All patients received fixed restorations, and the bridge survival rate was 100% after 1 year of loading. Small (<10%) but statistically significant dimensional changes in the grafted material were seen during the study period. Conclusions: Acceptable short-term results can be obtained with implants placed after the use of bovine hydroxyapatite and autogenous bone for maxillary sinus floor augmentation. These grafts show good resistance to resorption. © 2002 American Association of Oral and Maxillofacial Surgeons J Oral Maxillofac Surg 60:277-284, 2002

Osseointegrated implant for single-tooth replacement: a retrospective multicenter study on routine use in private practice.

Implant restorations first started with total edentulism. Later, the scientific community gave its approval for restorations in partial edentulism, and only recently some studies confirmed the validity of the treatment for single-tooth replacement. The purpose of the study was to evaluate implant survival and prosthesis stability of Brånemark implants (titanium screws) when used routinely for single-tooth replacement in all regions. Two hundred and fourteen patients received 252 implants for single-tooth replacement over a period of 8 years at five private clinics in Italy. The patients were treated in accordance with the protocol for Brånemark implants, and the data gathered have been analyzed according to established evaluation methods. During the observation period, 10 failures were recorded and 229 restorations were carried out. After the first year of loading, the total cumulative survival rate (CSR) was 96%, which then remained stable over the study time. The most frequent complication was loosening of the abutment screws (n = 22), amounting to 35% of all of the complications. This problem was related mainly to earlier types of abutments, whereas the more recent design, CeraOne abutment, showed a low frequency of screw loosening. The high survival rate, which is similar to that presented for prospective multicenter studies for single-tooth restorations with Brånemark implants, led to the conclusion that the use of this treatment modality is a reliable treatment for routine use in all oral regions.

Reverse torque testing and early loading failures: help or hindrance?

Reverse torque testing has been suggested to reduce the incidence of early loading failures during the first year of loading. However, the variables of bone density at stage II uncovery, the assessment of a small degree of implant rotation, and the effect of implant size and design have not been adequately evaluated. In addition, bone is weakest to shear forces, yet this is the primary force applied with reverse torque testing. This article reviews the benefits and disadvantages of reverse torque testing and suggests early crestal bone loss and failure of implants may be the result of this test, especially in less dense bone types. In addition, a nomenclature of implant failures is introduced to improve the correlation of information in the literature to the failure of implants in clinical practice.

A bone quality-based implant system: first year of prosthetic loading.

This interim report presents the data from a prospective study of BioHorizons, a bone quality-based implant system, with four implant designs. The surgical survival of 975 implants was 99.4%, with the survival 100% for D4 bone. Three critical phases of crestal bone loss have been identified: bone remodeling from stage I to stage II surgery; stage II uncovery to prosthesis delivery (transition period); and prosthesis delivery up to the first year of loading (early loading bone loss). The stage I to stage II uncovery crestal bone remodeling resulted in a mean vertical bone loss of 0.21 mm to 0.36 mm (SD = 0.90 mm), dependent on whether the implant became exposed in the oral cavity during osseous healing. No statistically significant difference was found among the four implant designs, diameter, bone density, or location. The stage II to prosthesis delivery mean vertical bone loss ranged from 0.12 mm to 0.20 mm. One hundred three consecutive patients (partially and totally edentulous) were restored, with 360 implants and 105 prostheses in function for a period of 12 to 26 months. No early loading implant failure occurred, and all patients with implants are in satisfactory to optimum health according to the Misch Implant Quality Scale. The mean early loading bone loss was 0.29 mm (SD = 0.99 mm). Past clinical reports in the literature indicate most failures or crestal bone loss occur by the first year of loading. This study suggests the bone quality based dental implant design minimizes overall implant failure and crestal bone loss, regardless of bone density.

Oral implants in combination with bone grafts: A 3-year retrospective multicenter study using the Brånemark 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 Brånemark implants were inserted, of which 624 were placed in bone grafts and alveolar bone. Twentyfive 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 mucosacovered, 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.